Recognition of LPS by TLR4: Potential for Anti-Inflammatory Therapies

PubMed Central

Nijland, Reindert; Hofland, Tom; van Strijp, Jos A. G.

2014-01-01

LPS molecules of marine bacteria show structures distinct from terrestrial bacteria, due to the different environment that marine bacteria live in. Because of these different structures, lipid A molecules from marine bacteria are most often poor stimulators of the Toll-like receptor 4 (TLR4) pathway. Due to their low stimulatory potential, these lipid A molecules are suggested to be applicable as antagonists of TLR4 signaling in sepsis patients, where this immune response is amplified and unregulated. Antagonizing lipid A molecules might be used for future therapies against sepsis, therapies that currently do not exist. In this review, we will discuss these differences in lipid A structures and their recognition by the immune system. The modifications present in marine lipid A structures are described, and their potential as LPS antagonists will be discussed. Finally, since clinical trials built on antagonizing lipid A molecules have proven unsuccessful, we propose to also focus on different aspects of the TLR4 signaling pathway when searching for new potential drugs. Furthermore, we put forward the notion that bacteria probably already produce inhibitors of TLR4 signaling, making these bacterial products interesting molecules to investigate for future sepsis therapies. PMID:25056632

Nanoscale infrared (IR) spectroscopy and imaging of structural lipids in human stratum corneum using an atomic force microscope to directly detect absorbed light from a tunable IR laser source.

PubMed

Marcott, Curtis; Lo, Michael; Kjoller, Kevin; Domanov, Yegor; Balooch, Guive; Luengo, Gustavo S

2013-06-01

An atomic force microscope (AFM) and a tunable infrared (IR) laser source have been combined in a single instrument (AFM-IR) capable of producing ~200-nm spatial resolution IR spectra and absorption images. This new capability enables IR spectroscopic characterization of human stratum corneum at unprecendented levels. Samples of normal and delipidized stratum corneum were embedded, cross-sectioned and mounted on ZnSe prisms. A pulsed tunable IR laser source produces thermomechanical expansion upon absorption, which is detected through excitation of contact resonance modes in the AFM cantilever. In addition to reducing the total lipid content, the delipidization process damages the stratum corneum morphological structure. The delipidized stratum corneum shows substantially less long-chain CH2 -stretching IR absorption band intensity than normal skin. AFM-IR images that compare absorbances at 2930/cm (lipid) and 3290/cm (keratin) suggest that regions of higher lipid concentration are located at the perimeter of corneocytes in the normal stratum corneum. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Do lipids shape the eukaryotic cell cycle?

PubMed

Furse, Samuel; Shearman, Gemma C

2018-01-01

Successful passage through the cell cycle presents a number of structural challenges to the cell. Inceptive studies carried out in the last five years have produced clear evidence of modulations in the lipid profile (sometimes referred to as the lipidome) of eukaryotes as a function of the cell cycle. This mounting body of evidence indicates that lipids play key roles in the structural transformations seen across the cycle. The accumulation of this evidence coincides with a revolution in our understanding of how lipid composition regulates a plethora of biological processes ranging from protein activity through to cellular signalling and membrane compartmentalisation. In this review, we discuss evidence from biological, chemical and physical studies of the lipid fraction across the cell cycle that demonstrate that lipids are well-developed cellular components at the heart of the biological machinery responsible for managing progress through the cell cycle. Furthermore, we discuss the mechanisms by which this careful control is exercised. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Determining Double Bond Position in Lipids Using Online Ozonolysis Coupled to Liquid Chromatography and Ion Mobility-Mass Spectrometry.

PubMed

Harris, Rachel A; May, Jody C; Stinson, Craig A; Xia, Yu; McLean, John A

2018-02-06

The increasing focus on lipid metabolism has revealed a need for analytical techniques capable of structurally characterizing lipids with a high degree of specificity. Lipids can exist as any one of a large number of double bond positional isomers, which are indistinguishable by single-stage mass spectrometry alone. Ozonolysis reactions coupled to mass spectrometry have previously been demonstrated as a means for localizing double bonds in unsaturated lipids. Here we describe an online, solution-phase reactor using ozone produced via a low-pressure mercury lamp, which generates aldehyde products diagnostic of cleavage at a particular double bond position. This flow-cell device is utilized in conjunction with structurally selective ion mobility-mass spectrometry. The lamp-mediated reaction was found to be effective for multiple lipid species in both positive and negative ionization modes, and the conversion efficiency from precursor to product ions was tunable across a wide range (20-95%) by varying the flow rate through the ozonolysis device. Ion mobility separation of the ozonolysis products generated additional structural information and revealed the presence of saturated species in a complex mixture. The method presented here is simple, robust, and readily coupled to existing instrument platforms with minimal modifications necessary. For these reasons, application to standard lipidomic workflows is possible and aids in more comprehensive structural characterization of a myriad of lipid species.

Characteristics of lipid micro- and nanoparticles based on supercritical formation for potential pharmaceutical application

PubMed Central

2013-01-01

The interest of the pharmaceutical industry in lipid drug delivery systems due to their prolonged release profile, biocompatibility, reduction of side effects, and so on is already known. However, conventional methods of preparation of these structures for their use and production in the pharmaceutical industry are difficult since these methods are usually multi-step and involve high amount of organic solvent. Furthermore, some processes need extreme conditions, which can lead to an increase of heterogeneity of particle size and degradation of the drug. An alternative for drug delivery system production is the utilization of supercritical fluid technique. Lipid particles produced by supercritical fluid have shown different physicochemical properties in comparison to lipid particles produced by classical methods. Such particles have shown more physical stability and narrower size distribution. So, in this paper, a critical overview of supercritical fluid-based processes for the production of lipid micro- and nanoparticles is given and the most important characteristics of each process are highlighted. PMID:24034341

Integrated femtosecond stimulated Raman scattering and two-photon fluorescence imaging of subcellular lipid and vesicular structures

NASA Astrophysics Data System (ADS)

Li, Xuesong; Lam, Wen Jiun; Cao, Zhe; Hao, Yan; Sun, Qiqi; He, Sicong; Mak, Ho Yi; Qu, Jianan Y.

2015-11-01

The primary goal of this study is to demonstrate that stimulated Raman scattering (SRS) as a new imaging modality can be integrated into a femtosecond (fs) nonlinear optical (NLO) microscope system. The fs sources of high pulse peak power are routinely used in multimodal nonlinear microscopy to enable efficient excitation of multiple NLO signals. However, with fs excitations, the SRS imaging of subcellular lipid and vesicular structures encounters significant interference from proteins due to poor spectral resolution and a lack of chemical specificity, respectively. We developed a unique NLO microscope of fs excitation that enables rapid acquisition of SRS and multiple two-photon excited fluorescence (TPEF) signals. In the in vivo imaging of transgenic C. elegans animals, we discovered that by cross-filtering false positive lipid signals based on the TPEF signals from tryptophan-bearing endogenous proteins and lysosome-related organelles, the imaging system produced highly accurate assignment of SRS signals to lipid. Furthermore, we demonstrated that the multimodal NLO microscope system could sequentially image lipid structure/content and organelles, such as mitochondria, lysosomes, and the endoplasmic reticulum, which are intricately linked to lipid metabolism.

Polyols, not sugars, determine the structural diversity of anti-streptococcal liamocins produced by Aureobasidium pullulans strain NRRL 50380

USDA-ARS?s Scientific Manuscript database

Liamocins are polyol-lipids produced by the fungus Aureobasidium pullulans, and have selective antibacterial activity against Streptococcus species. Liamocins produced by A. pullulans strain NRRL 50380 on sucrose medium have a D-mannitol head-group ester linked to 3,5-dihydroxydecanoate acyl chains,...

Detect changes in lipid-related structure of brown- and yellow-seeded Brassica Carinata seed during rumen fermentation in relation to basic chemical profile using ATR-FT/IR molecular spectroscopy with chemometrics.

PubMed

Xin, Hangshu; Yu, Peiqiang

2014-12-10

In this experiment, brown- and yellow-seeded Brassica carinata were selected to use as a model to investigate whether there were any changes in lipid-related structure make-up (including CH3 and CH2 asymmetric and symmetric stretching bands ca. 3010-2765cm(-1), unsaturated lipid band ca. 3043-2987cm(-1) and carbonyl CO ester band ca. 1789-1701cm(-1)) of oilseed tissue during rumen in situ incubation using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FT/IR). Correlations of lipid spectral characteristics with basic chemical profile and multivariate analyses for clarifying structural differences within lipid regions between two carinata seeds were also measured. The results showed that most spectral parameters in both carinata seeds were reduced as incubation time increased. However, the extent of changes in peak intensity of carbonyl CO ester group of brown-seeded carinata was not in fully accordance with that of yellow-seeded carinata. Additionally, these lipid structure features were highly correlated with the concentrations of OM (positively), CP (positively), NDF (negatively) and EE (positively) in carinata seeds after 0, 12, 24 and 48h of incubation. Based on the results from multivariate analyses, neither AHCA nor PCA could produce any distinctions in rumen residues between brown- and yellow-seeded carinata in spectra at lipid regions. It was concluded that besides for original feed samples, spectroscopic technique of ATR-FT/IR could also be used for rumen degradation residues in detecting changes in lipid-related molecular structure make-up. Further studies are needed to explore more details in lipid metabolism during ruminal fermentation with the combined consideration on both metabolic basis and molecular structural basis. Copyright © 2014 Elsevier B.V. All rights reserved.

Neutral Lipid Biosynthesis in Engineered Escherichia coli: Jojoba Oil-Like Wax Esters and Fatty Acid Butyl Esters

PubMed Central

Kalscheuer, Rainer; Stöveken, Tim; Luftmann, Heinrich; Malkus, Ursula; Reichelt, Rudolf; Steinbüchel, Alexander

2006-01-01

Wax esters are esters of long-chain fatty acids and long-chain fatty alcohols which are of considerable commercial importance and are produced on a scale of 3 million tons per year. The oil from the jojoba plant (Simmondsia chinensis) is the main biological source of wax esters. Although it has a multitude of potential applications, the use of jojoba oil is restricted, due to its high price. In this study, we describe the establishment of heterologous wax ester biosynthesis in a recombinant Escherichia coli strain by coexpression of a fatty alcohol-producing bifunctional acyl-coenzyme A reductase from the jojoba plant and a bacterial wax ester synthase from Acinetobacter baylyi strain ADP1, catalyzing the esterification of fatty alcohols and coenzyme A thioesters of fatty acids. In the presence of oleate, jojoba oil-like wax esters such as palmityl oleate, palmityl palmitoleate, and oleyl oleate were produced, amounting to up to ca. 1% of the cellular dry weight. In addition to wax esters, fatty acid butyl esters were unexpectedly observed in the presence of oleate. The latter could be attributed to solvent residues of 1-butanol present in the medium component, Bacto tryptone. Neutral lipids produced in recombinant E. coli were accumulated as intracytoplasmic inclusions, demonstrating that the formation and structural integrity of bacterial lipid bodies do not require specific structural proteins. This is the first report on substantial biosynthesis and accumulation of neutral lipids in E. coli, which might open new perspectives for the biotechnological production of cheap jojoba oil equivalents from inexpensive resources employing recombinant microorganisms. PMID:16461689

Neutral lipid biosynthesis in engineered Escherichia coli: jojoba oil-like wax esters and fatty acid butyl esters.

PubMed

Kalscheuer, Rainer; Stöveken, Tim; Luftmann, Heinrich; Malkus, Ursula; Reichelt, Rudolf; Steinbüchel, Alexander

2006-02-01

Wax esters are esters of long-chain fatty acids and long-chain fatty alcohols which are of considerable commercial importance and are produced on a scale of 3 million tons per year. The oil from the jojoba plant (Simmondsia chinensis) is the main biological source of wax esters. Although it has a multitude of potential applications, the use of jojoba oil is restricted, due to its high price. In this study, we describe the establishment of heterologous wax ester biosynthesis in a recombinant Escherichia coli strain by coexpression of a fatty alcohol-producing bifunctional acyl-coenzyme A reductase from the jojoba plant and a bacterial wax ester synthase from Acinetobacter baylyi strain ADP1, catalyzing the esterification of fatty alcohols and coenzyme A thioesters of fatty acids. In the presence of oleate, jojoba oil-like wax esters such as palmityl oleate, palmityl palmitoleate, and oleyl oleate were produced, amounting to up to ca. 1% of the cellular dry weight. In addition to wax esters, fatty acid butyl esters were unexpectedly observed in the presence of oleate. The latter could be attributed to solvent residues of 1-butanol present in the medium component, Bacto tryptone. Neutral lipids produced in recombinant E. coli were accumulated as intracytoplasmic inclusions, demonstrating that the formation and structural integrity of bacterial lipid bodies do not require specific structural proteins. This is the first report on substantial biosynthesis and accumulation of neutral lipids in E. coli, which might open new perspectives for the biotechnological production of cheap jojoba oil equivalents from inexpensive resources employing recombinant microorganisms.

Subnanometer structure of an asymmetric model membrane: Interleaflet coupling influences domain properties

DOE PAGES

Heberle, Frederick A.; Marquardt, Drew; Doktorova, Milka; ...

2016-04-29

Cell membranes possess a complex three-dimensional architecture, including nonrandom lipid lateral organization within the plane of a bilayer leaflet, and compositional asymmetry between the two leaflets. As a result, delineating the membrane structure–function relationship has been a highly challenging task. Even in simplified model systems, the interactions between bilayer leaflets are poorly understood, due in part to the difficulty of preparing asymmetric model membranes that are free from the effects of residual organic solvent or osmotic stress. To address these problems, we have modified a technique for preparing asymmetric large unilamellar vesicles (aLUVs) via cyclodextrin-mediated lipid exchange in order tomore » produce tensionless, solvent-free aLUVs suitable for a range of biophysical studies. Leaflet composition and structure were characterized using isotopic labeling strategies, which allowed us to avoid the use of bulky labels. NMR and gas chromatography provided precise quantification of the extent of lipid exchange and bilayer asymmetry, while small-angle neutron scattering (SANS) was used to resolve bilayer structural features with subnanometer resolution. Isotopically asymmetric POPC vesicles were found to have the same bilayer thickness and area per lipid as symmetric POPC vesicles, demonstrating that the modified exchange protocol preserves native bilayer structure. Partial exchange of DPPC into the outer leaflet of POPC vesicles produced chemically asymmetric vesicles with a gel/fluid phase-separated outer leaflet and a uniform, POPC-rich inner leaflet. SANS was able to separately resolve the thicknesses and areas per lipid of coexisting domains, revealing reduced lipid packing density of the outer leaflet DPPC-rich phase compared to typical gel phases. Lastly, our finding that a disordered inner leaflet can partially fluidize ordered outer leaflet domains indicates some degree of interleaflet coupling, and invites speculation on a role for bilayer asymmetry in modulating membrane lateral organization.« less

An Efficient Glycoblotting-Based Analysis of Oxidized Lipids in Liposomes and a Lipoprotein.

PubMed

Furukawa, Takayuki; Hinou, Hiroshi; Takeda, Seiji; Chiba, Hitoshi; Nishimura, Shin-Ichiro; Hui, Shu-Ping

2017-10-05

Although widely occurring lipid oxidation, which is triggered by reactive oxygen species (ROS), produces a variety of oxidized lipids, practical methods to efficiently analyze oxidized lipids remain elusive. Herein, it is shown that the glycoblotting platform can be used to analyze oxidized lipids. Analysis is based on the principle that lipid aldehydes, one of the oxidized lipid species, can be captured selectively, enriched, and detected. Moreover, 3-methyl-1-p-tolyltriazene (MTT) methylates phosphoric and carboxylic acids, and this MTT-mediated methylation is, in combination with conventional tandem mass spectrometry (MS/MS) analysis, an effective method for the structural analysis of oxidized lipids. By using three classes of standards, liposomes, and a lipoprotein, it is demonstrated that glycoblotting represents a powerful approach for focused lipidomics, even in complex macromolecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced lipid accumulation and biodiesel production by oleaginous Chlorella protothecoides under a structured heterotrophic-iron (II) induction strategy.

PubMed

Li, Yuqin; Mu, Jinxiu; Chen, Di; Xu, Hua; Han, Fangxin

2015-05-01

A structured heterotrophic-iron (II) induction (HII) strategy was proposed to enhance lipid accumulation in oleaginous Chlorella protothecoides. C. protothecoides subjected to heterotrophic-iron (II) induction achieved a favorable lipid accumulation up to 62 % and a maximum lipid productivity of 820.17 mg/day, representing 2.78-fold and 3.64-fold increase respectively over heterotrophic cultivation alone. HII-induced cells produced significantly elevated levels of 16:0, 18:1(Δ9), and 18:2(Δ9,12) fatty acids (over 90 %). The lipid contents and plant lipid-like fatty acid compositions exhibit the potential of HII-induced C. protothecoides as biodiesel feedstock. Furthermore, 31 altered proteins in HII-induced algal cells were successfully identified. These differentially expressed proteins were assigned into nine molecular function categories, including carbohydrate metabolism, lipid biosynthesis, Calvin cycle, cellular respiration, photosynthesis, energy and transport, protein biosynthesis, regulate and defense, and unclassified. Analysis using the Kyoto encyclopedia of genes and genomes and gene ontology annotation showed that malic enzyme, acyltransferase, and ACP were key metabolic checkpoints found to modulate lipid accumulation in C. protothecoides. The results provided possible applications of HII cultivation strategy in other microalgal species and new possibilities in developing genetic and metabolic engineering microalgae for desirable lipid productivity.

Automated structural classification of lipids by machine learning.

PubMed

Taylor, Ryan; Miller, Ryan H; Miller, Ryan D; Porter, Michael; Dalgleish, James; Prince, John T

2015-03-01

Modern lipidomics is largely dependent upon structural ontologies because of the great diversity exhibited in the lipidome, but no automated lipid classification exists to facilitate this partitioning. The size of the putative lipidome far exceeds the number currently classified, despite a decade of work. Automated classification would benefit ongoing classification efforts by decreasing the time needed and increasing the accuracy of classification while providing classifications for mass spectral identification algorithms. We introduce a tool that automates classification into the LIPID MAPS ontology of known lipids with >95% accuracy and novel lipids with 63% accuracy. The classification is based upon simple chemical characteristics and modern machine learning algorithms. The decision trees produced are intelligible and can be used to clarify implicit assumptions about the current LIPID MAPS classification scheme. These characteristics and decision trees are made available to facilitate alternative implementations. We also discovered many hundreds of lipids that are currently misclassified in the LIPID MAPS database, strongly underscoring the need for automated classification. Source code and chemical characteristic lists as SMARTS search strings are available under an open-source license at https://www.github.com/princelab/lipid_classifier. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Enzymatic synthesis of cocoa butter equivalent from olive oil and palmitic-stearic fatty acid mixture.

PubMed

Mohamed, Ibrahim O

2015-01-01

The main goal of the present research is to restructure olive oil triacylglycerol (TAG) using enzymatic acidolysis reaction to produce structured lipids that is close to cocoa butter in terms of TAG structure and melting characteristics. Lipase-catalyzed acidolysis of refined olive oil with a mixture of palmitic-stearic acids at different substrate ratios was performed in an agitated batch reactor maintained at constant temperature and agitation speed. The reaction attained steady-state conversion in about 5 h with an overall conversion of 92.6 % for the olive oil major triacylglycerol 1-palmitoy-2,3-dioleoyl glycerol (POO). The five major TAGs of the structured lipids produced with substrate mass ratio of 1:3 (olive oil/palmitic-stearic fatty acid mixture) were close to that of the cocoa butter with melting temperature between 32.6 and 37.7 °C. The proposed kinetics model used fits the experimental data very well.

Functionalization Pattern of Graphene Oxide Sheets Controls Entry or Produces Lipid Turmoil in Phospholipid Membranes.

PubMed

Dallavalle, Marco; Bottoni, Andrea; Calvaresi, Matteo; Zerbetto, Francesco

2018-05-09

Molecular dynamics, coarse-grained to the level of hydrophobic and hydrophilic interactions, shows that graphene oxide sheets, GOSs, can pierce through the phospholipid membrane and navigate the double layer only if the hydrophilic groups are randomly dispersed in the structure. Their behavior resembles that found in similar calculations for pristine graphene sheets. If the oxidation is located at the edge of the sheets, GOSs hover over the membrane and trigger a major reorganization of the lipids. The reorganization is the largest when the radius of the edge-functionalized sheet is similar to the length of the lipophilic chain of the lipids. In the reorganization, the heads of the lipid chains form dynamical structures that pictorially resemble the swirl of water flowing down a drain. All effects maximize the interaction between hydrophobic moieties on the one hand and lipophilic fragments on the other and are accompanied by a large number of lipid flip-flops. Possible biological consequences are discussed.

Techno-economic analysis of biodiesel and ethanol co-production from lipid-producing sugarcane: Biodiesel and Ethanol Co-Production from Lipid-Producing Sugarcane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Haibo; Long, Stephen; Singh, Vijay

Biodiesel production from vegetable oils has progressively increased over the past two decades. However, due to the low amounts of oil produced per hectare from temperate oilseed crops (e.g. soybean), the opportunities for further increasing biodiesel production are limited. Genetically modified lipid-producing sugarcane (lipid-cane) possesses great potential for producing biodiesel as an alternative feedstock because of sugarcane’s much higher productivity compared with soybean. In this study, techno-economic models were developed for biodiesel and ethanol coproduction from lipid-cane, assuming 2, 5, 10, or 20% lipid concentration in the harvested stem (dry mass basis). The models were compared with a conventional soybeanmore » biodiesel process model to assess lipid-cane’s competiveness. In the lipid-cane process model, the extracted lipids were used to produce biodiesel by transesterifi cation, and the remaining sugar was used to produce ethanol by fermentation. The results showed that the biodiesel production cost from lipid-cane decreased from $0.89/L to $0.59 /L as the lipid content increased from 2 to 20%; this cost was lower than that obtained for soybeans ($1.08/L). The ethanol production costs from lipid-cane were between $0.40/L and $0.46/L. The internal rate of return (IRR) for the soybean biodiesel process was 15.0%, and the IRR for the lipid-cane process went from 13.7 to 24.0% as the lipid content increased from 2 to 20%. Because of its high productivity, lipid-cane with 20% lipid content can produce 6700 L of biodiesel from each hectare of land, whereas soybean can only produce approximately 500 L of biodiesel from each hectare of land. This would indicate that continued efforts to achieve lipid-producing sugarcane could make large-scale replacement of fossil-fuel-derived diesel without unrealistic demands on land area.« less

Techno-economic analysis of biodiesel and ethanol co-production from lipid-producing sugarcane: Biodiesel and Ethanol Co-Production from Lipid-Producing Sugarcane

DOE PAGES

Huang, Haibo; Long, Stephen; Singh, Vijay

2016-03-07

Biodiesel production from vegetable oils has progressively increased over the past two decades. However, due to the low amounts of oil produced per hectare from temperate oilseed crops (e.g. soybean), the opportunities for further increasing biodiesel production are limited. Genetically modified lipid-producing sugarcane (lipid-cane) possesses great potential for producing biodiesel as an alternative feedstock because of sugarcane’s much higher productivity compared with soybean. In this study, techno-economic models were developed for biodiesel and ethanol coproduction from lipid-cane, assuming 2, 5, 10, or 20% lipid concentration in the harvested stem (dry mass basis). The models were compared with a conventional soybeanmore » biodiesel process model to assess lipid-cane’s competiveness. In the lipid-cane process model, the extracted lipids were used to produce biodiesel by transesterifi cation, and the remaining sugar was used to produce ethanol by fermentation. The results showed that the biodiesel production cost from lipid-cane decreased from $0.89/L to $0.59 /L as the lipid content increased from 2 to 20%; this cost was lower than that obtained for soybeans ($1.08/L). The ethanol production costs from lipid-cane were between $0.40/L and $0.46/L. The internal rate of return (IRR) for the soybean biodiesel process was 15.0%, and the IRR for the lipid-cane process went from 13.7 to 24.0% as the lipid content increased from 2 to 20%. Because of its high productivity, lipid-cane with 20% lipid content can produce 6700 L of biodiesel from each hectare of land, whereas soybean can only produce approximately 500 L of biodiesel from each hectare of land. This would indicate that continued efforts to achieve lipid-producing sugarcane could make large-scale replacement of fossil-fuel-derived diesel without unrealistic demands on land area.« less

A New Route to Liposil Formation by an Interfacial Sol-Gel Process Confined by Lipid Bilayer.

PubMed

Shen, Shukun; Yang, Lu; Lu, Yaxing; Chen, Jian-Gang; Song, Shaofei; Hu, Daodao; Parikh, Atul

2015-11-18

We report a new and simple approach to prepare a class of silica-reinforced liposomes with hybrid core-shell nanostructures. The amphiphilic natural structure of lipids was exploited to sequester hydrophobic molecules, namely precursor TEOS and pyrene, in the hydrophobic midplane of liposomal bilayer assemblies in the aqueous phase. Subsequent interfacial hydrolysis of TEOS at the bilayer/water interface and ensuing condensation within the hydrophobic interstices of the lipid bilayer drives silica formation in situ, producing a novel class of silica-lipid hybrid liposils. Structural characterization by scanning- and transmission electron microscopy confirm that the liposils so generated preserve closed topologies and size-monodipersity of the parent lecithin liposomes, and DSC-TGA and XRD measurements provide evidence for the silica coating. Monitoring fluorescence measurements using embedded pyrene yield detailed information on microenvironment changes, which occur during sol-gel process and shed light on the structural evolution during silica formation. We envisage that liposils formed by this simple, new approach, exploiting the hydrophobic core of the lipid bilayer to spatially localize silica-forming precursors enables preparation of stable liposils exhibiting capacity for cargo encapsulation, bicompatibility, and fluorescence monitoring, more generally opening a window for construction of stable, functional hybrid materials.

Biomaterials and the U.S. Navy.

DTIC Science & Technology

1984-07-10

one lipid film adsorbed on a solid substrate ( Langmuir - Blodgett films). By this method diffusion of the lipid molecules could be studied. It was also...produces a potent emulsifier, allowing utilization of liquid hydrocarbons, such as decane, dodecane, tetradecane, or hexadecane. The strain also...efficiency 0 L -2%). Even though the tertiary structure of rhodopsin is known to a 7A -16- understand collagen. They prepared poly L proline, a single

Construction of protocellular structures under simulated primitive earth conditions

NASA Astrophysics Data System (ADS)

Yanagawa, Hiroshi; Ogawa, Yoko; Kojima, Kiyotsugu; Ito, Masahiko

1988-09-01

We have developed experimental approaches for the construction of protocellular structures under simulated primitive earth conditions and studied their formation and characteristics. Three types of envelopes; protein envelopes, lipid envelopes, and lipid-protein envelopes are considered as candidates for protocellular structures. Simple protein envelopes and lipid envelopes are presumed to have originated at an early stage of chemical evolution, interaction mutually and then evolved into more complex envelopes composed of both lipids and proteins. Three kinds of protein envelopes were constructedin situ from amino acids under simulated primitive earth conditions such as a fresh water tide pool, a warm sea, and a submarine hydrothermal vent. One protein envelope was formed from a mixture of amino acid amides at 80 °C using multiple hydration-dehydration cycles. Marigranules, protein envelope structures, were produced from mixtures of glycine and acidic, basic and aromatic amino acids at 105 °C in a modified sea medium enriched with essential transition elements. Thermostable microspheres were also formed from a mixture of glycine, alanine, valine, and aspartic acid at 250 °C and above. The microspheres did not form at lower temperatures and consist of silicates and peptide-like polymers containing imide bonds and amino acid residues enriched in valine. Amphiphilic proteins with molecular weights of 2000 were necessary for the formation of the protein envelopes. Stable lipid envelopes were formed from different dialkyl phospholipids and fatty acids. Large, stable, lipid-protein envelopes were formed from egg lecithin and the solubilized marigranules. Polycations such as polylysine and polyhistidine, or basic proteins such as lysozyme and cytochromec also stabilized lipid-protein envelopes.

Single cell assessment of yeast metabolic engineering for enhanced lipid production using Raman and AFM-IR imaging.

PubMed

Kochan, Kamila; Peng, Huadong; Wood, Bayden R; Haritos, Victoria S

2018-01-01

Biodiesel is a valuable renewable fuel made from derivatized fatty acids produced in plants, animals, and oleaginous microbes. Of the latter, yeasts are of special interest due to their wide use in biotechnology, ability to synthesize fatty acids and store large amounts of triacylglycerols while utilizing non-food carbon sources. While yeast efficiently produce lipids, genetic modification and indeed, lipid pathway metabolic engineering, is usually required for cost-effective production. Traditionally, gas chromatography (GC) is used to measure fatty acid production and to track the success of a metabolic engineering strategy in a microbial culture; here we have employed vibrational spectroscopy approaches at population and single cell level of engineered yeast while simultaneously investigating metabolite levels in subcellular structures. Firstly, a strong correlation ( r 2  > 0.99) was established between Fourier transform infrared (FTIR) lipid in intact cells and GC analysis of fatty acid methyl esters in the differently engineered strains. Confocal Raman spectroscopy of individual cells carrying genetic modifications to enhance fatty acid synthesis and lipid accumulation revealed changes to the lipid body (LB), the storage organelle for lipids in yeast, with their number increasing markedly (up to tenfold higher); LB size was almost double in the strain that also expressed a LB stabilizing gene but considerable variation was also noted between cells. Raman spectroscopy revealed a clear trend toward reduced unsaturated fatty acid content in lipids of cells carrying more complex metabolic engineering. Atomic force microscopy-infrared spectroscopy (AFM-IR) analysis of individual cells indicated large differences in subcellular constituents between strains: cells of the most highly engineered strain had elevated lipid and much reduced carbohydrate in their cytoplasm compared with unmodified cells. Vibrational spectroscopy analysis allowed the simultaneous measurement of strain variability in metabolite production and impact on cellular structures as a result of different gene introductions or knockouts, within a lipid metabolic engineering strategy and these inform the next steps in comprehensive lipid engineering. Additionally, single cell spectroscopic analysis measures heterogeneity in metabolite production across microbial cultures under genetic modification, an emerging issue for efficient biotechnological production.

Membrane Remodeling by the Double-Barrel Scaffolding Protein of Poxvirus

PubMed Central

Hijnen, Marcel; Schult, Philipp; Pettikiriarachchi, Anne; Mitra, Alok K.; Coulibaly, Fasséli

2011-01-01

In contrast to most enveloped viruses, poxviruses produce infectious particles that do not acquire their internal lipid membrane by budding through cellular compartments. Instead, poxvirus immature particles are generated from atypical crescent-shaped precursors whose architecture and composition remain contentious. Here we describe the 2.6 Å crystal structure of vaccinia virus D13, a key structural component of the outer scaffold of viral crescents. D13 folds into two jellyrolls decorated by a head domain of novel fold. It assembles into trimers that are homologous to the double-barrel capsid proteins of adenovirus and lipid-containing icosahedral viruses. We show that, when tethered onto artificial membranes, D13 forms a honeycomb lattice and assembly products structurally similar to the viral crescents and immature particles. The architecture of the D13 honeycomb lattice and the lipid-remodeling abilities of D13 support a model of assembly that exhibits similarities with the giant mimivirus. Overall, these findings establish that the first committed step of poxvirus morphogenesis utilizes an ancestral lipid-remodeling strategy common to icosahedral DNA viruses infecting all kingdoms of life. Furthermore, D13 is the target of rifampicin and its structure will aid the development of poxvirus assembly inhibitors. PMID:21931553

Physical and chemical stability of marine lipid-based liposomes under acid conditions.

PubMed

Nacka, F; Cansell, M; Gouygou, J P.; Gerbeaud, C; Méléard, P; Entressangles, B

2001-03-01

Liposomes made from a marine lipid extract containing a high polyunsaturated fatty lipid ratio were submitted to large pH variations, ranging from 1 to 8. Shape transformations were followed by video microscopy using giant liposomes and micromanipulation experiments. Acidification induced a decrease of the vesicle size simultaneous to the appearance of invaginations. These pH-dependent structural rearrangements were interpreted in terms of osmotic shocks and chemical modifications of the membranes. Liposomes produced by direct filtration were studied using turbidity measurements and optical microscopy observations. A low pH led to an instantaneous vesicle aggregation and to complex supramolecular and/or morphological changes as a function of time. The subsequent buffer neutralization of the liposome suspensions induced a partial reversion of the aggregation phenomenon while the structural membrane rearrangements were persisting. Furthermore, weak chemical degradations (oxidation and hydrolysis) were evidenced when the vesicles were incubated at low pH up to a 24-h incubation time. Thus, although acidification revealed liposome size and shape changes, the bilayer structure was maintained indicating that marine lipid-based liposomes could be used as oral administration vectors.

Specific Adhesion of Lipid Membranes Can Simultaneously Produce Two Types of Lipid and Protein Heterogeneities

NASA Astrophysics Data System (ADS)

Shindell, Orrin; Micah, Natalie; Ritzer, Max; Gordon, Vernita

2015-03-01

Living cells adhere to one another and their environment. Adhesion is associated with re-organization of the lipid and protein components of the cell membrane. The resulting heterogeneities are functional structures involved in biological processes. We use artificial lipid membranes that contain a single type of binding protein. Before adhesion, the lipid, protein, and dye components in the membrane are well-mixed and constitute a single disordered-liquid phase (Ld) . After adhesion, two distinct types of heterogeneities coexist in the adhesion zone: a central domain of ordered lipid phase that excludes both binding proteins and membrane dye, and a peripheral domain of disordered lipid phase that is densely packed with adhesion proteins and enriched in membrane dye relative to the non-adhered portion of the vesicle. Thus, we show that adhesion that is mediated by only one type of protein can organize the lipid and protein components of the membranes into heterogeneities that resemble those found in biology, for example the immune synapse.

Investigating the Biosynthesis of Membrane-spanning Lipids Using Model Strains of Acidobacteria

NASA Astrophysics Data System (ADS)

Bradley, A. S.; Chubiz, L. M.

2016-12-01

Glycerol dialkyl glycerol tetraethers (GDGTs), deriving from the membrane-spanning lipids of microbes, are detected in a wide range of environments including marine and lacustrine waters, sediments, and in terrestrial soils. In sediments and soils, ratios of various GDGT structures form the basis of the TEX86 proxy based on isoprenoidal GDGTs derived from archaea, and the MBT/CBT proxy based on bacterial-derived branched GDGTs (brGDGTs), which is influenced by both temperature and pH. While the relationships of the proxy values to environmental variables have been empirically calibrated, much uncertainty remains in understanding genetic and physiological factors that affect the production of these lipid structures by microbes. In this study we compare two model bacterial strains - Edaphobacter aggregans WGB-1 , which has been previously demonstrated to produce brGDGTs (Damsté et al 2011) and Edaphobacter modestus JBG-1 (a non-brGDGT producer) to gain traction into understanding brGDGT production. We have sequenced each genome, facilitating comparisons that can be used to computationally generate hypotheses for genes involved in brGDGT biosynthesis. We will also report the results of initial experiments conducted to understand how the lipid profiles of each strain vary as a function of growth phase. Through a combination of genetic approaches and physiolotical experiments, we aim to bring new understanding to brGDGTs and how proxies derived from these lipids relate to environmental variables. Damsté et al. 2011 AEM 77: 4147

Comparative Proteome Analysis between High Lipid-Producing Strain Mucor circinelloides WJ11 and Low Lipid-Producing Strain CBS 277.49.

PubMed

Tang, Xin; Chen, Haiqin; Gu, Zhennan; Zhang, Hao; Chen, Yong Q; Song, Yuanda; Chen, Wei

2017-06-21

Mucor circinelloides is one of few oleaginous fungi that produces a useful oil rich in γ-linolenic acid, but it usually only produces <25% total lipid. Nevertheless, we isolated a new strain WJ11 that can produce up to 36% lipid of cell dry weight. In this study, we have systematically analyzed the global changes in protein levels between the high lipid-producing strain WJ11 and the low lipid-producing strain CBS 277.49 (15%, lipid/cell dry weight) at lipid accumulation phase through comparative proteome analysis. Proteome analysis demonstrated that the branched-chain amino acid and lysine metabolism, glycolytic pathway, and pentose phosphate pathway in WJ11 were up-regulated, while the activities of tricarboxylic acid cycle and branch point enzyme for synthesis of isoprenoids were retarded compared with CBS 277.49. The coordinated regulation at proteome level indicate that more acetyl-CoA and NADPH are provided for fatty acid biosynthesis in WJ11 compared with CBS 277.49.

7A projection map of the S-layer protein sbpA obtained with trehalose-embedded monolayer crystals.

PubMed

Norville, Julie E; Kelly, Deborah F; Knight, Thomas F; Belcher, Angela M; Walz, Thomas

2007-12-01

Two-dimensional crystallization on lipid monolayers is a versatile tool to obtain structural information of proteins by electron microscopy. An inherent problem with this approach is to prepare samples in a way that preserves the crystalline order of the protein array and produces specimens that are sufficiently flat for high-resolution data collection at high tilt angles. As a test specimen to optimize the preparation of lipid monolayer crystals for electron microscopy imaging, we used the S-layer protein sbpA, a protein with potential for designing arrays of both biological and inorganic materials with engineered properties for a variety of nanotechnology applications. Sugar embedding is currently considered the best method to prepare two-dimensional crystals of membrane proteins reconstituted into lipid bilayers. We found that using a loop to transfer lipid monolayer crystals to an electron microscopy grid followed by embedding in trehalose and quick-freezing in liquid ethane also yielded the highest resolution images for sbpA lipid monolayer crystals. Using images of specimens prepared in this way we could calculate a projection map of sbpA at 7A resolution, one of the highest resolution projection structures obtained with lipid monolayer crystals to date.

Computational Lipidomics and Lipid Bioinformatics: Filling In the Blanks.

PubMed

Pauling, Josch; Klipp, Edda

2016-12-22

Lipids are highly diverse metabolites of pronounced importance in health and disease. While metabolomics is a broad field under the omics umbrella that may also relate to lipids, lipidomics is an emerging field which specializes in the identification, quantification and functional interpretation of complex lipidomes. Today, it is possible to identify and distinguish lipids in a high-resolution, high-throughput manner and simultaneously with a lot of structural detail. However, doing so may produce thousands of mass spectra in a single experiment which has created a high demand for specialized computational support to analyze these spectral libraries. The computational biology and bioinformatics community has so far established methodology in genomics, transcriptomics and proteomics but there are many (combinatorial) challenges when it comes to structural diversity of lipids and their identification, quantification and interpretation. This review gives an overview and outlook on lipidomics research and illustrates ongoing computational and bioinformatics efforts. These efforts are important and necessary steps to advance the lipidomics field alongside analytic, biochemistry, biomedical and biology communities and to close the gap in available computational methodology between lipidomics and other omics sub-branches.

Mono-, di- and trimethylated homologues of isoprenoid tetraether lipid cores in archaea and environmental samples: mass spectrometric identification and significance.

PubMed

Knappy, Chris; Barillà, Daniela; Chong, James; Hodgson, Dominic; Morgan, Hugh; Suleman, Muhammad; Tan, Christine; Yao, Peng; Keely, Brendan

2015-12-01

Higher homologues of widely reported C(86) isoprenoid diglycerol tetraether lipid cores, containing 0-6 cyclopentyl rings, have been identified in (hyper)thermophilic archaea, representing up to 21% of total tetraether lipids in the cells. Liquid chromatography-tandem mass spectrometry confirms that the additional carbon atoms in the C(87-88) homologues are located in the etherified chains. Structures identified include dialkyl and monoalkyl ('H-shaped') tetraethers containing C(40-42) or C(81-82) hydrocarbons, respectively, many representing novel compounds. Gas chromatography-mass spectrometric analysis of hydrocarbons released from the lipid cores by ether cleavage suggests that the C(40) chains are biphytanes and the C(41) chains 13-methylbiphytanes. Multiple isomers, having different chain combinations, were recognised among the dialkyl lipids. Methylated tetraethers are produced by Methanothermobacter thermautotrophicus in varying proportions depending on growth conditions, suggesting that methylation may be an adaptive mechanism to regulate cellular function. The detection of methylated lipids in Pyrobaculum sp. AQ1.S2 and Sulfolobus acidocaldarius represents the first reported occurrences in Crenarchaeota. Soils and aquatic sediments from geographically distinct mesotemperate environments that were screened for homologues contained monomethylated tetraethers, with di- and trimethylated structures being detected occasionally. The structural diversity and range of occurrences of the C(87-89) tetraethers highlight their potential as complementary biomarkers for archaea in natural environments. Copyright © 2015 John Wiley & Sons, Ltd.

The dynamic life of arbuscular mycorrhizal fungal symbionts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bach, Elizabeth M.; Narvaez-Rivera, Giselle; Murray, Kira

One of the most fascinating biological interactions lies just beneath our feet. Arbuscular mycorrhizal fungi (AMF), fungi from the phylum Glomeromycota, form a text-book example of symbiosis with more than 80% of plant species. Yet, few people have the opportunity to observe AMF directly. Most AMF living within a root have three distinct body structures that can be observed under a microscope: hyphae, arbuscules, and vesicles. Hyphae are thin, wispy projections that reach out from the root and absorb nutrients like phosphorous from the soil (Fig. 1a, c). Hyphae transport nutrients back to the roots through arbuscules that extend intomore » the root cells. Arbuscules are highly branched networks that exchange the nutrients from the soil for carbohydrates produced by the host plant during photosynthesis. AMF are also able to store lipids in vesicles, which are small, round structures within the root cells (Fig. 1b, d). AMF produce the lipids stored in vesicles from plant-derived carbon and use them for energy when the plant is not actively photosynthesizing. The host plant cannot access lipids within vesicles, so their production represents a complete transfer of carbon from plant host to fungus. Most roots do not contain all AMF structures. Even on plants colonized by AMF, not all roots show signs of colonization. On some roots, a multitude of fungal structures are evident within the roots. On others, those structures are nowhere to be found.« less

Solid lipid dispersions: potential delivery system for functional ingredients in foods.

PubMed

Asumadu-Mensah, Aboagyewa; Smith, Kevin W; Ribeiro, Henelyta S

2013-07-01

Structured solid lipid (SL) systems have the advantages of long-term physical stability, low surfactant concentrations, and may exhibit controlled release of active ingredients. In this research work, the potential use of high-melting SLs for the production of the above structured SL carrier systems was investigated. Dispersions containing either SL or blend of solid lipid and oil (SL+O) were produced by a hot melt high-pressure homogenization method. Experiments involved the use of 3 different SLs for the disperse phase: stearic acid, candelilla wax and carnauba wax. Sunflower oil was incorporated in the disperse phase for the production of the dispersions containing lipid and oil. In order to evaluate the practical aspects of structured particles, analytical techniques were used including: static light scattering to measure particle sizes, transmission electron microscopy (TEM) for investigating particle morphology and differential scanning calorimetry (DSC) to investigate the crystallization behavior of lipids in bulk and in dispersions. Results showed different mean particle sizes depending on the type of lipid used in the disperse phase. Particle sizes for the 3 lipids were: stearic acid (SL: 195 ± 2.5 nm; SL+O: 138 ± 6.0 nm); candelilla wax (SL: 178 ± 1.7 nm; SL+O: 144 ± 0.6 nm); carnauba wax (SL: 303 ± 1.5 nm; SL+O: 295 ± 5.0 nm). TEM results gave an insight into the practical morphology, showing plate-like and needle-like structures. DSC investigations also revealed that SL dispersions melted and crystallized at lower temperatures than the bulk. This decrease can be explained by the small particle sizes of the dispersion, the high-specific surface area, and the presence of a surfactant. © 2013 Institute of Food Technologists®

ω-3 polyunsaturated fatty acids direct differentiation of the membrane phenotype in mesenchymal stem cells to potentiate osteogenesis

PubMed Central

Levental, Kandice R.; Surma, Michal A.; Skinkle, Allison D.; Lorent, Joseph H.; Zhou, Yong; Klose, Christian; Chang, Jeffrey T.; Hancock, John F.; Levental, Ilya

2017-01-01

Mammalian cells produce hundreds of dynamically regulated lipid species that are actively turned over and trafficked to produce functional membranes. These lipid repertoires are susceptible to perturbations from dietary sources, with potentially profound physiological consequences. However, neither the lipid repertoires of various cellular membranes, their modulation by dietary fats, nor their effects on cellular phenotypes have been widely explored. We report that differentiation of human mesenchymal stem cells (MSCs) into osteoblasts or adipocytes results in extensive remodeling of the plasma membrane (PM), producing cell-specific membrane compositions and biophysical properties. The distinct features of osteoblast PMs enabled rational engineering of membrane phenotypes to modulate differentiation in MSCs. Specifically, supplementation with docosahexaenoic acid (DHA), a lipid component characteristic of osteoblast membranes, induced broad lipidomic remodeling in MSCs that reproduced compositional and structural aspects of the osteoblastic PM phenotype. The PM changes induced by DHA supplementation potentiated osteogenic differentiation of MSCs concurrent with enhanced Akt activation at the PM. These observations prompt a model wherein the DHA-induced lipidome leads to more stable membrane microdomains, which serve to increase Akt activity and thereby enhance osteogenic differentiation. More broadly, our investigations suggest a general mechanism by which dietary fats affect cellular physiology through remodeling of membrane lipidomes, biophysical properties, and signaling. PMID:29134198

The structure of the CD3 ζζ transmembrane dimer in POPC and raft-like lipid bilayer: a molecular dynamics study.

PubMed

Petruk, Ariel Alcides; Varriale, Sonia; Coscia, Maria Rosaria; Mazzarella, Lelio; Merlino, Antonello; Oreste, Umberto

2013-11-01

Plasma membrane lipids significantly affect assembly and activity of many signaling networks. The present work is aimed at analyzing, by molecular dynamics simulations, the structure and dynamics of the CD3 ζζ dimer in palmitoyl-oleoyl-phosphatidylcholine bilayer (POPC) and in POPC/cholesterol/sphingomyelin bilayer, which resembles the raft membrane microdomain supposed to be the site of the signal transducing machinery. Both POPC and raft-like environment produce significant alterations in structure and flexibility of the CD3 ζζ with respect to nuclear magnetic resonance (NMR) model: the dimer is more compact, its secondary structure is slightly less ordered, the arrangement of the Asp6 pair, which is important for binding to the Arg residue in the alpha chain of the T cell receptor (TCR), is stabilized by water molecules. Different interactions of charged residues with lipids at the lipid-cytoplasm boundary occur when the two environments are compared. Furthermore, in contrast to what is observed in POPC, in the raft-like environment correlated motions between transmembrane and cytoplasmic regions are observed. Altogether the data suggest that when the TCR complex resides in the raft domains, the CD3 ζζ dimer assumes a specific conformation probably necessary to the correct signal transduction. © 2013.

CryoEM structures of membrane pore and prepore complex reveal cytolytic mechanism of Pneumolysin

PubMed Central

van Pee, Katharina; Neuhaus, Alexander; D'Imprima, Edoardo; Mills, Deryck J; Kühlbrandt, Werner; Yildiz, Özkan

2017-01-01

Many pathogenic bacteria produce pore-forming toxins to attack and kill human cells. We have determined the 4.5 Å structure of the ~2.2 MDa pore complex of pneumolysin, the main virulence factor of Streptococcus pneumoniae, by cryoEM. The pneumolysin pore is a 400 Å ring of 42 membrane-inserted monomers. Domain 3 of the soluble toxin refolds into two ~85 Å β-hairpins that traverse the lipid bilayer and assemble into a 168-strand β-barrel. The pore complex is stabilized by salt bridges between β-hairpins of adjacent subunits and an internal α-barrel. The apolar outer barrel surface with large sidechains is immersed in the lipid bilayer, while the inner barrel surface is highly charged. Comparison of the cryoEM pore complex to the prepore structure obtained by electron cryo-tomography and the x-ray structure of the soluble form reveals the detailed mechanisms by which the toxin monomers insert into the lipid bilayer to perforate the target membrane. DOI: http://dx.doi.org/10.7554/eLife.23644.001 PMID:28323617

The Adipophilin C Terminus Is a Self-folding Membrane-binding Domain That Is Important for Milk Lipid Secretion*

PubMed Central

Chong, Brandi M.; Russell, Tanya D.; Schaack, Jerome; Orlicky, David J.; Reigan, Philip; Ladinsky, Mark; McManaman, James L.

2011-01-01

Cytoplasmic lipid droplets (CLD) in mammary epithelial cells undergo secretion by a unique membrane envelopment process to produce milk lipids. Adipophilin (ADPH/Plin2), a member of the perilipin/PAT family of lipid droplet-associated proteins, is hypothesized to mediate CLD secretion through interactions with apical plasma membrane elements. We found that the secretion of CLD coated by truncated ADPH lacking the C-terminal region encoding a putative four-helix bundle structure was impaired relative to that of CLD coated by full-length ADPH. We used homology modeling and analyses of the solution and membrane binding properties of purified recombinant ADPH C terminus to understand how this region possibly mediates CLD secretion. Homology modeling supports the concept that the ADPH C terminus forms a four-helix bundle motif and suggests that this structure can form stable membrane bilayer interactions. Circular dichroism and protease mapping studies confirmed that the ADPH C terminus is an independently folding α-helical structure that is relatively resistant to urea denaturation. Liposome binding studies showed that the purified C terminus binds to phospholipid membranes through electrostatic dependent interactions, and cell culture studies documented that it localizes to the plasma membrane. Collectively, these data provide direct evidence that the ADPH C terminus forms a stable membrane binding helical structure that is important for CLD secretion. We speculate that interactions between the four-helix bundle of ADPH and membrane phospholipids may be an initial step in milk lipid secretion. PMID:21383012

Stable isotope-assisted NMR characterization of interaction between lipid A and sarcotoxin IA, a cecropin-type antibacterial peptide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yagi-Utsumi, Maho; Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603; Yamaguchi, Yoshiki

Highlights: ► Recombinant sarcotoxin IA was successfully produced with {sup 13}C- and {sup 15}N-labeling. ► Sarcotoxin IA adopts an N-terminal α-helix upon binding to lipid A-embedding micelles. ► Two lysine residues are involved in lipid A-mediated antibacterial activities. -- Abstract: Sarcotoxin IA is a 39-residue cecropin-type peptide from Sarcophaga peregrina. This peptide exhibits antibacterial activity against Gram-negative bacteria through its interaction with lipid A, a core component of lipopolysaccharides. To acquire detailed structural information on this specific interaction, we performed NMR analysis using bacterially expressed sarcotoxin IA analogs with {sup 13}C- and {sup 15}N-labeling along with lipid A-embedding micelles composedmore » of dodecylphosphocholine. By inspecting the stable isotope-assisted NMR data, we revealed that the N-terminal segment (Leu3–Arg18) of sarcotoxin IA formed an amphiphilic α-helix upon its interaction with the aqueous micelles. Furthermore, chemical shift perturbation data indicated that the amino acid residues displayed on this α-helix were involved in the specific interaction with lipid A. On the basis of these data, we successfully identified Lys4 and Lys5 as key residues in the interaction with lipid A and the consequent antibacterial activity. Therefore, these results provide unique information for designing chemotherapeutics based on antibacterial peptide structures.« less

Novel changes in discoidal high density lipoprotein morphology: a molecular dynamics study.

PubMed

Catte, Andrea; Patterson, James C; Jones, Martin K; Jerome, W Gray; Bashtovyy, Denys; Su, Zhengchang; Gu, Feifei; Chen, Jianguo; Aliste, Marcela P; Harvey, Stephen C; Li, Ling; Weinstein, Gilbert; Segrest, Jere P

2006-06-15

ApoA-I is a uniquely flexible lipid-scavenging protein capable of incorporating phospholipids into stable particles. Here we report molecular dynamics simulations on a series of progressively smaller discoidal high density lipoprotein particles produced by incremental removal of palmitoyloleoylphosphatidylcholine via four different pathways. The starting model contained 160 palmitoyloleoylphosphatidylcholines and a belt of two antiparallel amphipathic helical lipid-associating domains of apolipoprotein (apo) A-I. The results are particularly compelling. After a few nanoseconds of molecular dynamics simulation, independent of the starting particle and method of size reduction, all simulated double belts of the four lipidated apoA-I particles have helical domains that impressively approximate the x-ray crystal structure of lipid-free apoA-I, particularly between residues 88 and 186. These results provide atomic resolution models for two of the particles produced by in vitro reconstitution of nascent high density lipoprotein particles. These particles, measuring 95 angstroms and 78 angstroms by nondenaturing gradient gel electrophoresis, correspond in composition and in size/shape (by negative stain electron microscopy) to the simulated particles with molar ratios of 100:2 and 50:2, respectively. The lipids of the 100:2 particle family form minimal surfaces at their monolayer-monolayer interface, whereas the 50:2 particle family displays a lipid pocket capable of binding a dynamic range of phospholipid molecules.

Novel Changes in Discoidal High Density Lipoprotein Morphology: A Molecular Dynamics Study

PubMed Central

Catte, Andrea; Patterson, James C.; Jones, Martin K.; Jerome, W. Gray; Bashtovyy, Denys; Su, Zhengchang; Gu, Feifei; Chen, Jianguo; Aliste, Marcela P.; Harvey, Stephen C.; Li, Ling; Weinstein, Gilbert; Segrest, Jere P.

2006-01-01

ApoA-I is a uniquely flexible lipid-scavenging protein capable of incorporating phospholipids into stable particles. Here we report molecular dynamics simulations on a series of progressively smaller discoidal high density lipoprotein particles produced by incremental removal of palmitoyloleoylphosphatidylcholine via four different pathways. The starting model contained 160 palmitoyloleoylphosphatidylcholines and a belt of two antiparallel amphipathic helical lipid-associating domains of apolipoprotein (apo) A-I. The results are particularly compelling. After a few nanoseconds of molecular dynamics simulation, independent of the starting particle and method of size reduction, all simulated double belts of the four lipidated apoA-I particles have helical domains that impressively approximate the x-ray crystal structure of lipid-free apoA-I, particularly between residues 88 and 186. These results provide atomic resolution models for two of the particles produced by in vitro reconstitution of nascent high density lipoprotein particles. These particles, measuring 95 Å and 78 Å by nondenaturing gradient gel electrophoresis, correspond in composition and in size/shape (by negative stain electron microscopy) to the simulated particles with molar ratios of 100:2 and 50:2, respectively. The lipids of the 100:2 particle family form minimal surfaces at their monolayer-monolayer interface, whereas the 50:2 particle family displays a lipid pocket capable of binding a dynamic range of phospholipid molecules. PMID:16581834

Effects of flavonoid glycosides obtained from a Ginkgo biloba extract fraction on the physical and oxidative stabilities of oil-in-water emulsions prepared from a stripped structured lipid with a low omega-6 to omega-3 ratio.

PubMed

Yang, Dan; Wang, Xiang-Yu; Gan, Lu-Jing; Zhang, Hua; Shin, Jung-Ah; Lee, Ki-Teak; Hong, Soon-Taek

2015-05-01

In this study, we have produced a structured lipid with a low ω6/ω3 ratio by lipase-catalysed interesterification with perilla and grape seed oils (1:3, wt/wt). A Ginkgo biloba leaf extract was fractionated in a column packed with HP-20 resin, producing a flavonoid glycoside fraction (FA) and a biflavone fraction (FB). FA exhibited higher antioxidant capacity than FB, showing 58.4 mmol gallic acid equivalent (GAE)/g-of-total-phenol-content, 58.8 mg quercetin equivalent (QUE)/g-of-total-flavonoid-content, 4.5 mmol trolox/g-of-trolox-equivalent antioxidant capacity, 0.14 mg extract/mL-of-free-radical-scavenging-activity (DPPH assay, IC50), and 2.3 mmol Fe2SO4 · 7H2O/g-of-ferric-reducing-antioxidant-power. The oil-in-water emulsion containing the stripped structured lipid as an oil phase with FA exhibited the highest stability and the lowest oil globule diameters (d43 and d32), where the aggregation was unnoticeable by Turbiscan and particle size analyses during 30 days of storage. Furthermore, FA was effective in retarding the oxidation of the emulsions. Copyright © 2014 Elsevier Ltd. All rights reserved.

The expanding field of cannabimimetic and related lipid mediators

PubMed Central

Bradshaw, Heather B; Walker, J Michael

2005-01-01

The discovery of the endogenous cannabimimetic lipid mediators, anandamide and 2-arachidonoyl glycerol, opened the door to the discovery of other endogenous lipid mediators similar in structure and function. The majority of these compounds do not bind appreciably to known cannabinoid receptors; yet some of them produce cannabimimetic effects while others exert actions through novel mechanisms that remain to be elucidated. This review explores the growing diversity of recently discovered putative lipid mediators and their relationship to the endogenous cannabinoid system. The possibility that there remain many unidentified signalling lipids coupled with the evidence that many of these yield bioactive metabolites due to actions of known enzymes (e.g. cyclooxygenases, lipoxygenases, cytochrome P450s) suggests the existence of a large and complex family of lipid mediators about which only little is known at this time. The elucidation of the biochemistry and pharmacology of these compounds may provide therapeutic targets for a variety of conditions including sleep dysfunction, eating disorders, cardiovascular disease, as well as inflammation and pain. PMID:15655504

Effects of amphipathic profile regularization on structural order and interaction with membrane models of two highly cationic branched peptides with β-sheet propensity.

PubMed

Serra, Ilaria; Casu, Mariano; Ceccarelli, Matteo; Gameiro, Paula; Rinaldi, Andrea C; Scorciapino, Mariano Andrea

2018-07-01

Antimicrobial peptides attracted increasing interest in last decades due to the rising concern of multi-drug resistant pathogens. Dendrimeric peptides are branched molecules with multiple copies of one peptide functional unit bound to the central core. Compared to linear analogues, they usually show improved activity and lower susceptibility to proteases. Knowledge of structure-function relationship is fundamental to tailor their properties. This work is focused on SB056, the smallest example of dendrimeric peptide, whose amino acid sequence is WKKIRVRLSA. Two copies are bound to the α- and ε- nitrogen of one lysine core. An 8-aminooctanamide was added at the C-terminus to improve membrane affinity. Its propensity for β-type structures is also interesting, since helical peptides were already thoroughly studied. Moreover, SB056 maintains activity at physiological osmolarity, a typical limitation of natural peptides. An optimized analogue with improved performance was designed, β-SB056, which differs only in the relative position of the first two residues (KWKIRVRLSA). This produced remarkable differences. Structure order and aggregation behavior were characterized by using complementary techniques and membrane models with different negative charge. Infrared spectroscopy showed different propensity for ordered β-sheets. Lipid monolayers' surface pressure was measured to estimate the area/peptide and the ability to perturb lipid packing. Fluorescence spectroscopy was applied to compare peptide insertion into the lipid bilayer. Such small change in primary structure produced fundamental differences in their aggregation behavior. A regular amphipathic peptide's primary structure was responsible for ordered β-sheets in a charge independent fashion, in contrast to unordered aggregates formed by the former analogue. Copyright © 2018 Elsevier Inc. All rights reserved.

A painful link between the TRPV1 channel and lysophosphatidic acid.

PubMed

Morales-Lázaro, Sara L; Rosenbaum, Tamara

2015-03-15

The Transient Receptor Potential Vanilloid 1 (TRPV1) ion channel is expressed mainly by sensory neurons that detect noxious stimuli from the environment such as high temperatures and pungent compounds (such as allicin and capsaicin) and has been extensively linked to painful and inflammatory processes. This extraordinary protein also responds to endogenous stimuli among which we find molecules of a lipidic nature. We recently described that lysophosphatidic acid (LPA), a bioactive lysophospholipid linked to the generation and maintenance of pain, can directly activate TRPV1 and produce pain by binding to the channels' C-terminal region, specifically to residue K710. In an effort to further understand how activation of TRPV1 is achieved by this negatively-charged lipid, we used several synthetic and naturally-occurring lipids to determine the structural requirements that need to be met by these charged lipids in order to produce the activation of TRPV1. In this review, we detail the findings obtained by other research groups and our own on the field of TRPV1-regulation by negatively-charged lipids and discuss the possible therapeutic relevance of these findings on the basis of the role of TRPV1 in pathophysiological processes. Copyright © 2014 Elsevier Inc. All rights reserved.

Lipid droplets of arbuscular mycorrhizal fungi emerge in concert with arbuscule collapse.

PubMed

Kobae, Yoshihiro; Gutjahr, Caroline; Paszkowski, Uta; Kojima, Tomoko; Fujiwara, Toru; Hata, Shingo

2014-11-01

Plants share photosynthetically fixed carbon with arbuscular mycorrhizal (AM) fungi to maintain their growth and nutrition. AM fungi are oleogenic fungi that contain numerous lipid droplets in their syncytial mycelia during most of their life cycle. These lipid droplets are probably used for supporting growth of extraradical mycelia and propagation; however, when and where the lipid droplets are produced remains unclear. To address these issues, we investigated the correlation between intracellular colonization stages and the appearance of fungal lipid droplets in roots by a combination of vital staining of fungal structures, selective staining of lipids and live imaging. We discovered that a surge of lipid droplets coincided with the collapse of arbuscular branches, indicating that arbuscule collapse and the emergence of lipid droplets may be associated processes. This phenomenon was observed in the model AM fungus Rhizophagus irregularis and the ancestral member of AM fungi Paraglomus occultum. Because the collapsing arbuscules were metabolically inactive, the emerged lipid droplets are probably derived from preformed lipids but not de novo synthesized. Our observations highlight a novel mode of lipid release by AM fungi. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Permeability and electrical properties of planar lipid membranes from thylakoid lipids.

PubMed Central

Fuks, B; Homblé, F

1994-01-01

Electrical measurements were carried out on planar lipid membranes from thylakoid lipids. The specific capacitance of membranes formed from decane-containing monogalactosyldiacylglycerol (MGDG), which accounts for 57% of the total lipid content of thylakoids, showed that it adopted a bilayer structure. Solvent-free bilayers of MGDG were not formed, with very rare exceptions, indicating that decane is required to stabilize the planar conformation. However, this cone-shaped lipid produces bilayer structures in combination with other cylindrical thylakoid lipids even in the absence of organic solvent. We compared the properties of solvent-free and decane-containing bilayers from MGDG, soybean lecithin, and the quaternary mixture of lipids similar to that found in vivo. The conductance of decane-MGDG was 26 times higher than that of decane-lecithin. The flux through the decane-lecithin bilayer was found to be slightly dependent on pH, whereas the decane-MGDG membrane was not. The specific conductance of bilayers formed from the quaternary mixture of lipids was 5 to 10 times larger than lecithin (with alkane or not). Further experiments with bilayers made in the presence of a KCl gradient showed that decane-MGDG, decane-MGDG/DGDG/SQDG/PG, and solvent-free MGDG/DGDG/SQDG/PG were cation-selective. The permeability coefficient for potassium ranged from 4.9 to 8.3 x 10(-11) cm s-1. The permeability coefficient for protons in galactolipids, however, was determined to be about six orders of magnitude higher than the value for potassium ions. The HCl permeation mechanism through the lipid membranes was determined from diffusion potentials measured in HCl gradients. Our results suggest that HCl was not transported as neutral molecules. The data is discussed with regard to the function of galactolipids in the ion transport through thylakoid membranes. PMID:8061192

The unusual lipid binding proteins of parasitic helminths and their potential roles in parasitism and as therapeutic targets.

PubMed

Franchini, Gisela R; Pórfido, Jorge L; Ibáñez Shimabukuro, Marina; Rey Burusco, María F; Bélgamo, Julián A; Smith, Brian O; Kennedy, Malcolm W; Córsico, Betina

2015-02-01

In this review paper we aim at presenting the current knowledge on structural aspects of soluble lipid binding proteins (LBPs) found in parasitic helminths and to discuss their potential role as novel drug targets. Helminth parasites produce and secrete a great variety of LBPs that may participate in the acquisition of nutrients from their host, such as fatty acids and cholesterol. It is also postulated that LBPs might interfere in the regulation of the host׳s immune response by sequestering lipidic intermediates or delivering bioactive lipids. A detailed comprehension of the structure of these proteins, as well as their interactions with ligands and membranes, is important to understand host-parasite relationships that they may mediate. This information could also contribute to determining the role that these proteins may play in the biology of parasitic helminths and how they modulate the immune systems of their hosts, and also towards the development of new therapeutics and prevention of the diseases caused by these highly pathogenic parasites. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lipid biomarkers for bacterial ecosystems: studies of cultured organisms, hydrothermal environments and ancient sediments

NASA Technical Reports Server (NTRS)

Summons, R. E.; Jahnke, L. L.; Simoneit, B. R.

1996-01-01

This paper forms part of our long-term goal of using molecular structure and carbon isotopic signals preserved as hydrocarbons in ancient sediments to improve understanding of the early evolution of Earth's surface environment. We are particularly concerned with biomarkers which are informative about aerobiosis. Here, we combine bacterial biochemistry with the organic geochemistry of contemporary and ancient hydrothermal ecosystems to construct models for the nature, behaviour and preservation potential of primitive microbial communities. We use a combined molecular and isotopic approach to characterize lipids produced by cultured bacteria and test a variety of culture conditions which affect their biosynthesis. This information is then compared with lipid mixtures isolated from contemporary hot springs and evaluated for the kinds of chemical change that would accompany burial and incorporation into the sedimentary record. In this study we have shown that growth temperature does not appear to alter isotopic fractionation within the lipid classes produced by a methanotropic bacterium. We also found that cultured cyanobacteria biosynthesize diagnostic methylalkanes and dimethylalkanes with the latter only made when growing under low pCO2. In an examination of a microbial mat sample from Octopus Spring, Yellowstone National Park (USA), we could readily identify chemical structures with 13C contents which were diagnostic for the phototrophic organisms such as cyanobacteria and Chloroflexus. We could not, however, find molecular evidence for operation of a methane cycle in the particular mat samples we studied.

Effects of gramicidin-A on the adsorption of phospholipids to the air–water interface

PubMed Central

Biswas, Samares C.; Rananavare, Shankar B.; Hall, Stephen B.

2012-01-01

Prior studies suggest that the hydrophobic surfactant proteins, SP-B and SP-C, promote adsorption of the lipids in pulmonary surfactant to an air–water interface by stabilizing a negatively curved rate-limiting structure that is intermediate between bilayer vesicles and the surface film. This model predicts that other peptides capable of stabilizing negative curvature should also promote lipid adsorption. Previous reports have shown that under appropriate conditions, gramicidin-A (GrA) induces dioleoyl phosphatidylcholine (DOPC), but not dimyristoyl phosphatidylcholine (DMPC), to form the negatively curved hexagonal-II (HII) phase. The studies reported here determined if GrA would produce the same effects on adsorption of DMPC and DOPC that the hydrophobic surfactant proteins have on the surfactant lipids. Small angle X-ray scattering and 31P-nuclear magnetic resonance confirmed that at the particular conditions used to study adsorption, GrA induced DOPC to form the HII phase, but DMPC remained lamellar. Measurements of surface tension showed that GrA in vesicles produced a general increase in the rate of adsorption for both phospholipids. When restricted to the interface, however, in preexisting films, GrA with DOPC, but not with DMPC, replicated the ability of the surfactant proteins to promote adsorption of vesicles containing only the lipids. The correlation between the structural and functional effects of GrA with the two phospholipids, and the similar effects on adsorption of GrA with DOPC and the hydrophobic surfactant proteins with the surfactant lipids fit with the model in which SP-B and SP-C facilitate adsorption by stabilizing a rate-limiting intermediate with negative curvature. PMID:16242116

LMSD: LIPID MAPS structure database

PubMed Central

Sud, Manish; Fahy, Eoin; Cotter, Dawn; Brown, Alex; Dennis, Edward A.; Glass, Christopher K.; Merrill, Alfred H.; Murphy, Robert C.; Raetz, Christian R. H.; Russell, David W.; Subramaniam, Shankar

2007-01-01

The LIPID MAPS Structure Database (LMSD) is a relational database encompassing structures and annotations of biologically relevant lipids. Structures of lipids in the database come from four sources: (i) LIPID MAPS Consortium's core laboratories and partners; (ii) lipids identified by LIPID MAPS experiments; (iii) computationally generated structures for appropriate lipid classes; (iv) biologically relevant lipids manually curated from LIPID BANK, LIPIDAT and other public sources. All the lipid structures in LMSD are drawn in a consistent fashion. In addition to a classification-based retrieval of lipids, users can search LMSD using either text-based or structure-based search options. The text-based search implementation supports data retrieval by any combination of these data fields: LIPID MAPS ID, systematic or common name, mass, formula, category, main class, and subclass data fields. The structure-based search, in conjunction with optional data fields, provides the capability to perform a substructure search or exact match for the structure drawn by the user. Search results, in addition to structure and annotations, also include relevant links to external databases. The LMSD is publicly available at PMID:17098933

Analysis of population structures of the microalga Acutodesmus obliquus during lipid production using multi-dimensional single-cell analysis.

PubMed

Sandmann, Michael; Schafberg, Michaela; Lippold, Martin; Rohn, Sascha

2018-04-19

Microalgae bear a great potential to produce lipids for biodiesel, feed, or even food applications. To understand the still not well-known single-cell dynamics during lipid production in microalgae, a novel single-cell analytical technology was applied to study a well-established model experiment. Multidimensional single-cell dynamics were investigated with a non-supervised image analysis technique that utilizes data from epi-fluorescence microscopy. Reliability of this technique was successfully proven via reference analysis. The technique developed was used to determine cell size, chlorophyll amount, neutral lipid amount, and deriving properties on a single-cellular level in cultures of the biotechnologically promising alga Acutodesmus obliquus. The results illustrated a high correlation between cell size and chlorophyll amount, but a very low and dynamic correlation between cell size, lipid amount, and lipid density. During growth conditions under nitrogen starvation, cells with low chlorophyll content tend to start the lipid production first and the cell suspension differentiated in two subpopulations with significantly different lipid contents. Such quantitative characterization of single-cell dynamics of lipid synthesizing algae was done for the first time and the potential of such simple technology is highly relevant to other biotechnological applications and to deeper investigate the process of microalgal lipid accumulation.

Comparison of Biochemical Activities between High and Low Lipid-Producing Strains of Mucor circinelloides: An Explanation for the High Oleaginicity of Strain WJ11.

PubMed

Tang, Xin; Chen, Haiqin; Chen, Yong Q; Chen, Wei; Garre, Victoriano; Song, Yuanda; Ratledge, Colin

2015-01-01

The oleaginous fungus, Mucor circinelloides, is one of few fungi that produce high amounts of γ-linolenic acid (GLA); however, it usually only produces <25% lipid. Nevertheless, a new strain (WJ11) isolated in this laboratory can produce lipid up to 36% (w/w) cell dry weight (CDW). We have investigated the potential mechanism of high lipid accumulation in M. circinelloides WJ11 by comparative biochemical analysis with a low lipid-producing strain, M. circinelloides CBS 277.49, which accumulates less than 15% (w/w) lipid. M. circinelloides WJ11 produced more cell mass than that of strain CBS 277.49, although with slower glucose consumption. In the lipid accumulation phase, activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in strain WJ11 were greater than in CBS 277.49 by 46% and 17%, respectively, and therefore may provide more NADPH for fatty acid biosynthesis. The activities of NAD+:isocitrate dehydrogenase and NADP+:isocitrate dehydrogenase, however, were 43% and 54%, respectively, lower in WJ11 than in CBS 277.49 and may retard the tricarboxylic acid cycle and thereby provide more substrate for ATP:citrate lyase (ACL) to produce acetyl-CoA. Also, the activities of ACL and fatty acid synthase in the high lipid-producing strain, WJ11, were 25% and 56%, respectively, greater than in strain CBS 277.49. These enzymes may therefore cooperatively regulate the fatty acid biosynthesis in these two strains.

A Brief Literature Overview of Various Routes to Biorenewable Fuels from Lipids for the National Alliance for Advanced Biofuels and Bio-products (NAABB) Consortium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albrecht, Karl O.; Hallen, Richard T.

2011-03-29

Renewable methods of producing transportation fuels are currently the focus of numerous large research efforts across the globe. Renewable fuel produced from algal lipids is one aspect of this research that could have profound implications on future transportation fuel requirements. However, technical challenges remain in several areas of algal-lipid-based fuels. These challenges include the identification and development of robust and productive algal species as well as extraction methods to recover the produced lipids. Not the least of these technical challenges is the conversion of the algae lipids to fungible fuels. This brief literature review focuses primarily on state-of-the-art “downstream” applicationsmore » of producing fuel from fats and lipids, which can be applied to ongoing research with algae-derived lipids.« less

Structuration of lipid bases with fully hydrogenated crambe oil and sorbitan monostearate for obtaining zero-trans/low sat fats.

PubMed

Stahl, Marcella Aparecida; Buscato, Monise Helen Masuchi; Grimaldi, Renato; Cardoso, Lisandro Pavie; Ribeiro, Ana Paula Badan

2018-05-01

Several studies have shown that excessive intake of trans and saturated fatty acids is associated with an increased risk of cardiovascular disease. In this context, the food industry has sought alternatives for the development of healthy lipid bases, with higher levels of unsaturated fatty acids, adapting to current legislation. The incorporation of structuring agents into liquid oils has proven to be a potential alternative for obtaining semi-plastic lipid bases with reduced levels of saturated fatty acids. Thus, the objective of this study was to produce zero trans fat bases with lower saturated fatty acids levels. Palm oil (PO) was used as a zero trans-lipid base reference because of its technological functionality. Blends containing different proportions of high oleic sunflower oil (HOSO) and PO were prepared as follows: control 100: 0; 80:20; 60:40; 40:60; 20:80; and 100: 0 PO: HOSO (w/w%), respectively. Then, 3% of fully hydrogenated crambe oil (FHCO) and 3% sorbitan monostearate (SMS) were added to the blends as structuring agents, forming the structured (S) blends. The addition of HOSO to the PO decreased the saturated fatty acids by up to 30.6%, with consequent increase of unsaturated fatty acids, especially oleic acid. The joint action of the SMS and the FCHO allowed for obtaining structured blends with plastic and spreadability characteristics, as well as modifications throughout the crystallization process of the original blends. Copyright © 2018 Elsevier Ltd. All rights reserved.

Light-induced dynamic structural color by intracellular 3D photonic crystals in brown algae.

PubMed

Lopez-Garcia, Martin; Masters, Nathan; O'Brien, Heath E; Lennon, Joseph; Atkinson, George; Cryan, Martin J; Oulton, Ruth; Whitney, Heather M

2018-04-01

Natural photonic crystals are responsible for strong reflectance at selective wavelengths in different natural systems. We demonstrate that intracellular opal-like photonic crystals formed from lipids within photosynthetic cells produce vivid structural color in the alga Cystoseira tamariscifolia . The reflectance of the opaline vesicles is dynamically responsive to environmental illumination. The structural color is present in low light-adapted samples, whereas higher light levels produce a slow disappearance of the structural color such that it eventually vanishes completely. Once returned to low-light conditions, the color re-emerges. Our results suggest that these complex intracellular natural photonic crystals are responsive to environmental conditions, changing their packing structure reversibly, and have the potential to manipulate light for roles beyond visual signaling.

Lipid droplet analysis using in vitro bovine oocytes and embryos.

PubMed

Ordoñez-Leon, E A; Merchant, H; Medrano, A; Kjelland, M; Romo, S

2014-04-01

The aim of this study was to quantify the content of lipid droplets in bovine oocytes and embryos from Bos indicus (Bi), Bos taurus (Bt) and Bos indicus × Bos taurus (Bi × Bt). Oocytes were aspirated post-mortem and subjected to in vitro maturation, in vitro fertilization and in vitro development; the medium employed at each stage (TCM-199, TALP, SOF) was supplemented with (i) serum replacement (SR), (ii) foetal calf serum (FCS) or (iii) oestrous cow serum (ECS). The structure and distribution of the lipid droplets were established using electron microscopy, but were quantified using an optical microscope on semi-fine toluidine blue-stained sections. The highest percentage of embryos corresponded to those produced with FCS and ECS, which differed from embryos generated with SR (p < 0.05). The highest percentage of morulae and the lowest percentage of blastocysts were obtained with the SR supplement (p < 0.05). The oocytes cultured in FCS demonstrated a higher number of lipid droplets compared to those cultured in SR and ECS (p < 0.05). Less accumulation of lipids was observed in embryos supplemented with SR. The lowest and highest numbers of lipid droplets in oocytes corresponded to the Bi and Bt strain, respectively. The lowest amount of lipid droplets in embryos was observed in Bi (p < 0.05). In conclusion, supplementation of the in vitro development culture medium (synthetic oviduct fluid) with a synthetic substitute serum produced similar results in terms of embryo development compared to those obtained with FCS, but a decreased degree of lipid droplet accumulation was observed in the in vitro-cultured embryos. © 2014 Blackwell Verlag GmbH.

Development of an up-grading process to produce MLM structured lipids from sardine discards.

PubMed

Morales-Medina, R; Munio, M; Guadix, A; Guadix, E M

2017-08-01

The aim of the work was to produce MLM structured lipids with caprylic acid (M) as medium chain fatty acid located at the external bonds of the glycerol backbone and concentrated polyunsaturated fatty acids (L) from sardine discards (Sardine pilchardus) in the central bond of the glycerol. To that end, the following steps were conducted: (i) fish oil extraction, (ii) Omega-3 free fatty acids (FFA) concentration (low temperature winterization), (iii) two-steps enzymatic esterification and (iv) triacylglycerols (TAG) purification (liquid column chromatography). The resultant purified triacylglycerols accomplished with the oxidative state (peroxide and anisidine value, PV and AV) required for refined oils. As enzymatic treatment, Omega-3 concentrate FFA (Omega-3>600mg Omega-3 per g oil) were esterified with dicaprylic glycerol employing Novozyme 435. This process presented high regioselectivity, with ∼80mol% of concentrated fatty acids esterified at the sn-2 position. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enzymatic Synthesis of Refined Olive Oil-Based Structured Lipid Containing Omega -3 and -6 Fatty Acids for Potential Application in Infant Formula.

PubMed

Li, Ruoyu; Sabir, Jamal S M; Baeshen, Nabih A; Akoh, Casimir C

2015-11-01

Structured lipids (SLs) containing palmitic, docosahexaenoic (DHA), and gamma-linolenic (GLA) acids were produced using refined olive oil, tripalmitin, and ethyl esters of DHA single cell oil and GLA ethyl esters. Immobilized Lipozyme TL IM lipase was used as the biocatalyst. The SLs were characterized for fatty acid profile, triacylglycerol (TAG) molecular species, solid fat content, oxidative stability index, and melting and crystallization profiles and compared to physical blend of substrates, extracted fat from commercial infant formula (IFF), and milk fat. 49.28 mol% of palmitic acid was found at the sn-2 position of SL TAG and total DHA and GLA composition were 0.73 and 5.00 mol%, respectively. The total oleic acid content was 36.13 mol% which was very close to the 30.49% present in commercial IFF. Comparable solid fat content profiles were also found between SLs and IFF. The SLs produced have potential for use in infant formulas. © 2015 Institute of Food Technologists®

Detergent Optimized Membrane Protein Reconstitution in Liposomes for Solid State NMR

PubMed Central

2015-01-01

For small helical membrane proteins, their structures are highly sensitive to their environment, and solid state NMR is a structural technique that can characterize these membrane proteins in native-like lipid bilayers and proteoliposomes. To date, a systematic method by which to evaluate the effect of the solubilizing detergent on proteoliposome preparations for solid state NMR of membrane proteins has not been presented in the literature. A set of experiments are presented aimed at determining the conditions most amenable to dialysis mediated reconstitution sample preparation. A membrane protein from M. tuberculosis is used to illustrate the method. The results show that a detergent that stabilizes the most protein is not always ideal and sometimes cannot be removed by dialysis. By focusing on the lipid and protein binding properties of the detergent, proteoliposome preparations can be readily produced, which provide double the signal-to-noise ratios for both the oriented sample and magic angle spinning solid state NMR. The method will allow more membrane protein drug targets to be structurally characterized in lipid bilayer environments. PMID:24665863

Hybrid lipid-based nanostructures

NASA Astrophysics Data System (ADS)

Dayani, Yasaman

Biological membranes serve several important roles, such as structural support of cells and organelles, regulation of ionic and molecular transport, barriers to non-mediated transport, contact between cells within tissues, and accommodation of membrane proteins. Membrane proteins and other vital biomolecules incorporated into the membrane need a lipid membrane to function. Due to importance of lipid bilayers and their vital function in governing many processes in the cell, the development of various models as artificial lipid membranes that can mimic cell membranes has become a subject of great interest. Using different models of artificial lipid membranes, such as liposomes, planar lipid bilayers and supported or tethered lipid bilayers, we are able to study many biophysical processes in biological membranes. The ability of different molecules to interact with and change the structure of lipid membranes can be also investigated in artificial lipid membranes. An important application of lipid bilayer-containing interfaces is characterization of novel membrane proteins for high throughput drug screening studies to investigate receptor-drug interactions and develop biosensor systems. Membrane proteins need a lipid bilayer environment to preserve their stability and functionality. Fabrication of materials that can interact with biomolecules like proteins necessitates the use of lipid bilayers as a mimic of cell membranes. The objective of this research is to develop novel hybrid lipid-based nanostructures mimicking biological membranes. Toward this aim, two hybrid biocompatible structures are introduced: lipid bilayer-coated multi-walled carbon nanotubes (MWCNTs) and hydrogel-anchored liposomes with double-stranded DNA anchors. These structures have potential applications in biosensing, drug targeting, drug delivery, and biophysical studies of cell membranes. In the first developed nanostructure, lipid molecules are covalently attached to the surfaces of MWCNTs, and then, using a sonication process, a uniform lipid bilayer that supports the incorporation of membrane proteins is formed. These bilayer-coated carbon nanotubes are highly dispersible and stable in aqueous solution, and they can be used in development of various biosensors and energy producing devices. In the other hybrid nanostructure, the lipid bilayer of a liposome is covalently anchored to a biocompatible poly(ethylene) glycol (PEG) hydrogel core using double-stranded DNA (dsDNA) linkers. Release studies shows that nano-size hydrogel-anchored liposomes are exceptionally stable, and they can be used as biomimetic model membranes that mimic the connectivity between the cytoskeleton and the plasma membrane. After lipid bilayer removal, dsDNA linkers can provide programmable nanogels decorated with oligonucleotides with potential sites for further molecular assembly. These stable nanostructures can be useful for oligonucleotide and drug delivery applications. The developed hydrogel-anchored liposomes are exploited for encapsulation and intracellular delivery of therapeutic peptide. Peptides with anti-cancer properties are successfully encapsulated in hydrogel core of pH-sensitive liposomes during rehydration process. Liposomes release their cargo at acidic pH. Confocal microscopy confirms the intracellular delivery of liposomes through an endocytotic pathway.

Synthesis of structured lipids by lipase-catalyzed interesterification of triacetin with camellia oil methyl esters and preliminary evaluation of their plasma lipid-lowering effect in mice.

PubMed

Cao, Yu; Qi, Suijian; Zhang, Yang; Wang, Xiaoning; Yang, Bo; Wang, Yonghua

2013-03-25

Structured lipids (SLCTs triacylglycerols with short- and long-chain acyl residues) were synthesized by interesterification of triacetin and fatty acid methyl esters (FAMEs) from camellia oil, followed by molecular distillation for purification. Different commercial immobilized lipases (Lipozyme RM IM and Novozyme 435), the substrate molar ratios of FAMEs to triacetin, the reaction temperatures and the lipase amounts were studied for their efficiency in producing SLCTs. Results showed that Novozyme 435 was more suitable for this reaction system. Moreover, the optimal reaction conditions for the highest conversion of FAMEs and the highest LLS-TAGs (triacylglycerols with one short- and two long-chain acyl residues) yields were achieved at a molar ratio of FAMEs to triacetin of 3:1, 50 °C of reaction temperature and a lipase amount of 4% (w/v). Scale-up was conducted based on the optimized reaction conditions. Results showed that after 24 h of reaction , the conversion rate of FAMEs was 82.4% and the rate of disubstituted triacetin was 52.4 mol%. The final product yield rate was 94.6%. The effects of the synthesized SLCTs on the plasma lipid level of fasting mice were also studied. The SLCTs could effectively lessen the total triacylglycerol levels in plasma compared to the triacylglycerol group in fasting NIH mice. It suggested that this type of structured lipid might be beneficial for human health, especially for the prevention of obesity.

Bioactive Structure of Membrane Lipids and Natural Products Elucidated by a Chemistry-Based Approach.

PubMed

Murata, Michio; Sugiyama, Shigeru; Matsuoka, Shigeru; Matsumori, Nobuaki

2015-08-01

Determining the bioactive structure of membrane lipids is a new concept, which aims to examine the functions of lipids with respect to their three-dimensional structures. As lipids are dynamic by nature, their "structure" does not refer solely to a static picture but also to the local and global motions of the lipid molecules. We consider that interactions with lipids, which are completely defined by their structures, are controlled by the chemical, functional, and conformational matching between lipids and between lipid and protein. In this review, we describe recent advances in understanding the bioactive structures of membrane lipids bound to proteins and related molecules, including some of our recent results. By examining recent works on lipid-raft-related molecules, lipid-protein interactions, and membrane-active natural products, we discuss current perspectives on membrane structural biology. © 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Serine Lipids of Porphyromonas gingivalis Are Human and Mouse Toll-Like Receptor 2 Ligands

PubMed Central

Clark, Robert B.; Cervantes, Jorge L.; Maciejewski, Mark W.; Farrokhi, Vahid; Nemati, Reza; Yao, Xudong; Anstadt, Emily; Fujiwara, Mai; Wright, Kyle T.; Riddle, Caroline; La Vake, Carson J.; Salazar, Juan C.; Finegold, Sydney

2013-01-01

The total cellular lipids of Porphyromas gingivalis, a known periodontal pathogen, were previously shown to promote dendritic cell activation and inhibition of osteoblasts through engagement of Toll-like receptor 2 (TLR2). The purpose of the present investigation was to fractionate all lipids of P. gingivalis and define which lipid classes account for the TLR2 engagement, based on both in vitro human cell assays and in vivo studies in mice. Specific serine-containing lipids of P. gingivalis, called lipid 654 and lipid 430, were identified in specific high-performance liquid chromatography fractions as the TLR2-activating lipids. The structures of these lipids were defined using tandem mass spectrometry and nuclear magnetic resonance methods. In vitro, both lipid 654 and lipid 430 activated TLR2-expressing HEK cells, and this activation was inhibited by anti-TLR2 antibody. In contrast, TLR4-expressing HEK cells failed to be activated by either lipid 654 or lipid 430. Wild-type (WT) or TLR2-deficient (TLR2−/−) mice were injected with either lipid 654 or lipid 430, and the effects on serum levels of the chemokine CCL2 were measured 4 h later. Administration of either lipid 654 or lipid 430 to WT mice resulted in a significant increase in serum CCL2 levels; in contrast, the administration of lipid 654 or lipid 430 to TLR2−/− mice resulted in no increase in serum CCL2. These results thus identify a new class of TLR2 ligands that are produced by P. gingivalis that likely play a significant role in mediating inflammatory responses both at periodontal sites and, potentially, in other tissues where these lipids might accumulate. PMID:23836823

Anomalous partitioning of water in coexisting liquid phases of lipid multilayers near 100% relative humidity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Yicong; Ghosh, Sajal K.; Bera, Sambhunath

2015-11-30

X-ray diffraction is used to determine the hydration dependence of a ternary mixture lipid multilayer structure which has phase separated into liquid-ordered (Lo) and liquid-disordered (Ld) phases. An anomaly is observed in the swelling behavior of the Ld phase at a relative humidity (RH) close to 100%, which is different from the anomalous swelling happens close to the main lipid gel-fluid transition. The lamellar repeat distance of the Ld phase swells by an extra 4 Å, well beyond the equilibrium spacing predicted by the inter-bilayer forces. This anomalous swelling is caused by the hydrophobic mismatch energy at the domain boundaries,more » which produces surprisingly long range effect.« less

Phenotypic variability and selection of lipid-producing microalgae in a microfluidic centrifuge

NASA Astrophysics Data System (ADS)

Estévez-Torres, André.; Mestler, Troy; Austin, Robert H.

2010-03-01

Isogenic cells are known to display various expression levels that may result in different phenotypes within a population. Here we focus on the phenotypic variability of a species of unicellular algae that produce neutral lipids. Lipid-producing algae are one of the most promising sources of biofuel. We have implemented a simple microfluidic method to assess lipid-production variability in a population of algae that relays on density differences. We will discuss the reasons of this variability and address the promising avenues of this technique for directing the evolution of algae towards high lipid productivity.

Functionalized Vesicles by Microfluidic Device.

PubMed

Vallejo, Derek; Lee, Shih-Hui; Lee, Abraham

2017-01-01

In recent years, lipid vesicles have become popular vehicles for the creation of biosensors. Vesicles can hold reaction components within a selective permeable membrane that provides an ideal environment for membrane protein biosensing elements. The lipid bilayer allows a protein to retain its native structure and function, and the membrane fluidity can allow for conformational changes and physiological interactions with target analytes. Here, we present two methods for the production of giant unilamellar vesicles (GUVs) within a microfluidic device that can be used as the basis for a biosensor. The vesicles are produced from water-in-oil-in-water (W/O/W) double emulsion templates using a nonvolatile oil phase. To create the GUVs, the oil can be removed via extraction with ethanol, or by altering the interfacial tension between the oil and carrier solution causing the oil to retract into a cap on one side of the structure, leaving behind an exposed lipid bilayer. Methods to integrate sensing elements and membrane protein pores onto the vesicles are also introduced in this work.

The association of serum choline with linear growth failure in young children from rural Malawi

USDA-ARS?s Scientific Manuscript database

Choline is an essential nutrient for cell structure, cell signaling, neurotransmission, lipid transport, and bone formation. Choline can be irreversibly converted to betaine, a major source of methyl groups. Trimethylene N-oxide (TMAO), a proatherogenic molecule, is produced from the metabolism of d...

Lipid-protein nanodiscs for cell-free production of integral membrane proteins in a soluble and folded state: comparison with detergent micelles, bicelles and liposomes.

PubMed

Lyukmanova, E N; Shenkarev, Z O; Khabibullina, N F; Kopeina, G S; Shulepko, M A; Paramonov, A S; Mineev, K S; Tikhonov, R V; Shingarova, L N; Petrovskaya, L E; Dolgikh, D A; Arseniev, A S; Kirpichnikov, M P

2012-03-01

Production of integral membrane proteins (IMPs) in a folded state is a key prerequisite for their functional and structural studies. In cell-free (CF) expression systems membrane mimicking components could be added to the reaction mixture that promotes IMP production in a soluble form. Here lipid-protein nanodiscs (LPNs) of different lipid compositions (DMPC, DMPG, POPC, POPC/DOPG) have been compared with classical membrane mimicking media such as detergent micelles, lipid/detergent bicelles and liposomes by their ability to support CF synthesis of IMPs in a folded and soluble state. Three model membrane proteins of different topology were used: homodimeric transmembrane (TM) domain of human receptor tyrosine kinase ErbB3 (TM-ErbB3, 1TM); voltage-sensing domain of K(+) channel KvAP (VSD, 4TM); and bacteriorhodopsin from Exiguobacterium sibiricum (ESR, 7TM). Structural and/or functional properties of the synthesized proteins were analyzed. LPNs significantly enhanced synthesis of the IMPs in a soluble form regardless of the lipid composition. A partial disintegration of LPNs composed of unsaturated lipids was observed upon co-translational IMP incorporation. Contrary to detergents the nanodiscs resulted in the synthesis of ~80% active ESR and promoted correct folding of the TM-ErbB3. None of the tested membrane mimetics supported CF synthesis of correctly folded VSD, and the protocol of the domain refolding was developed. The use of LPNs appears to be the most promising approach to CF production of IMPs in a folded state. NMR analysis of (15)N-Ile-TM-ErbB3 co-translationally incorporated into LPNs shows the great prospects of this membrane mimetics for structural studies of IMPs produced by CF systems. Copyright © 2011 Elsevier B.V. All rights reserved.

Structural Determinants of the Transient Receptor Potential 1 (TRPV1) Channel Activation by Phospholipid Analogs*

PubMed Central

Morales-Lázaro, Sara L.; Serrano-Flores, Barbara; Llorente, Itzel; Hernández-García, Enrique; González-Ramírez, Ricardo; Banerjee, Souvik; Miller, Duane; Gududuru, Veeresh; Fells, James; Norman, Derek; Tigyi, Gabor; Escalante-Alcalde, Diana; Rosenbaum, Tamara

2014-01-01

The transient receptor potential vanilloid 1 (TRPV1) ion channel is a polymodal protein that responds to various stimuli, including capsaicin (the pungent compound found in chili peppers), extracellular acid, and basic intracellular pH, temperatures close to 42 °C, and several lipids. Lysophosphatidic acid (LPA), an endogenous lipid widely associated with neuropathic pain, is an agonist of the TRPV1 channel found in primary afferent nociceptors and is activated by other noxious stimuli. Agonists or antagonists of lipid and other chemical natures are known to possess specific structural requirements for producing functional effects on their targets. To better understand how LPA and other lipid analogs might interact and affect the function of TRPV1, we set out to determine the structural features of these lipids that result in the activation of TRPV1. By changing the acyl chain length, saturation, and headgroup of these LPA analogs, we established strict requirements for activation of TRPV1. Among the natural LPA analogs, we found that only LPA 18:1, alkylglycerophosphate 18:1, and cyclic phosphatidic acid 18:1, all with a monounsaturated C18 hydrocarbon chain activate TRPV1, whereas polyunsaturated and saturated analogs do not. Thus, TRPV1 shows a more restricted ligand specificity compared with LPA G-protein-coupled receptors. We synthesized fatty alcohol phosphates and thiophosphates and found that many of them with a single double bond in position Δ9, 10, or 11 and Δ9 cyclopropyl group can activate TRPV1 with efficacy similar to capsaicin. Finally, we developed a pharmacophore and proposed a mechanistic model for how these lipids could induce a conformational change that activates TRPV1. PMID:25035428

Structural determinants of the transient receptor potential 1 (TRPV1) channel activation by phospholipid analogs.

PubMed

Morales-Lázaro, Sara L; Serrano-Flores, Barbara; Llorente, Itzel; Hernández-García, Enrique; González-Ramírez, Ricardo; Banerjee, Souvik; Miller, Duane; Gududuru, Veeresh; Fells, James; Norman, Derek; Tigyi, Gabor; Escalante-Alcalde, Diana; Rosenbaum, Tamara

2014-08-29

The transient receptor potential vanilloid 1 (TRPV1) ion channel is a polymodal protein that responds to various stimuli, including capsaicin (the pungent compound found in chili peppers), extracellular acid, and basic intracellular pH, temperatures close to 42 °C, and several lipids. Lysophosphatidic acid (LPA), an endogenous lipid widely associated with neuropathic pain, is an agonist of the TRPV1 channel found in primary afferent nociceptors and is activated by other noxious stimuli. Agonists or antagonists of lipid and other chemical natures are known to possess specific structural requirements for producing functional effects on their targets. To better understand how LPA and other lipid analogs might interact and affect the function of TRPV1, we set out to determine the structural features of these lipids that result in the activation of TRPV1. By changing the acyl chain length, saturation, and headgroup of these LPA analogs, we established strict requirements for activation of TRPV1. Among the natural LPA analogs, we found that only LPA 18:1, alkylglycerophosphate 18:1, and cyclic phosphatidic acid 18:1, all with a monounsaturated C18 hydrocarbon chain activate TRPV1, whereas polyunsaturated and saturated analogs do not. Thus, TRPV1 shows a more restricted ligand specificity compared with LPA G-protein-coupled receptors. We synthesized fatty alcohol phosphates and thiophosphates and found that many of them with a single double bond in position Δ9, 10, or 11 and Δ9 cyclopropyl group can activate TRPV1 with efficacy similar to capsaicin. Finally, we developed a pharmacophore and proposed a mechanistic model for how these lipids could induce a conformational change that activates TRPV1. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Emulsion design to improve the delivery of functional lipophilic components.

PubMed

McClements, David Julian

2010-01-01

The food industry has used emulsion science and technology for many years to create a diverse range of food products, such as milk, cream, soft drinks, nutritional beverages, dressings, mayonnaise, sauces, dips, deserts, ice cream, margarine, and butter. The majority of these food products are conventional oil-in-water (O/W) or water-in-oil (W/O) type emulsions. Recently, there has been increasing interest within the food industry in either improving or extending the functional performance of foods using novel structured emulsions. This article reviews recent developments in the creation of structured emulsions that could be used by the food and other industries, including nanoemulsions, multiple emulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. These structured emulsions can be produced from food-grade [generally recognized as safe (GRAS)] ingredients (e.g., lipids, proteins, polysaccharides, surfactants, and minerals), using simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, production, performance, and potential applications of each type of structured emulsion system are discussed.

Light-induced dynamic structural color by intracellular 3D photonic crystals in brown algae

PubMed Central

2018-01-01

Natural photonic crystals are responsible for strong reflectance at selective wavelengths in different natural systems. We demonstrate that intracellular opal-like photonic crystals formed from lipids within photosynthetic cells produce vivid structural color in the alga Cystoseira tamariscifolia. The reflectance of the opaline vesicles is dynamically responsive to environmental illumination. The structural color is present in low light–adapted samples, whereas higher light levels produce a slow disappearance of the structural color such that it eventually vanishes completely. Once returned to low-light conditions, the color re-emerges. Our results suggest that these complex intracellular natural photonic crystals are responsive to environmental conditions, changing their packing structure reversibly, and have the potential to manipulate light for roles beyond visual signaling. PMID:29651457

Synthesis of arborane triterpenols by a bacterial oxidosqualene cyclase

NASA Astrophysics Data System (ADS)

Banta, Amy B.; Wei, Jeremy H.; Gill, Clare C. C.; Giner, José-Luis; Welander, Paula V.

2017-01-01

Cyclic triterpenoids are a broad class of polycyclic lipids produced by bacteria and eukaryotes. They are biologically relevant for their roles in cellular physiology, including membrane structure and function, and biochemically relevant for their exquisite enzymatic cyclization mechanism. Cyclic triterpenoids are also geobiologically significant as they are readily preserved in sediments and are used as biomarkers for ancient life throughout Earth's history. Isoarborinol is one such triterpenoid whose only known biological sources are certain angiosperms and whose diagenetic derivatives (arboranes) are often used as indicators of terrestrial input into aquatic environments. However, the occurrence of arborane biomarkers in Permian and Triassic sediments, which predates the accepted origin of angiosperms, suggests that microbial sources of these lipids may also exist. In this study, we identify two isoarborinol-like lipids, eudoraenol and adriaticol, produced by the aerobic marine heterotrophic bacterium Eudoraea adriatica. Phylogenetic analysis demonstrates that the E. adriatica eudoraenol synthase is an oxidosqualene cyclase homologous to bacterial lanosterol synthases and distinct from plant triterpenoid synthases. Using an Escherichia coli heterologous sterol expression system, we demonstrate that substitution of four amino acid residues in a bacterial lanosterol synthase enabled synthesis of pentacyclic arborinols in addition to tetracyclic sterols. This variant provides valuable mechanistic insight into triterpenoid synthesis and reveals diagnostic amino acid residues to differentiate between sterol and arborinol synthases in genomic and metagenomic datasets. Our data suggest that there may be additional bacterial arborinol producers in marine and freshwater environments that could expand our understanding of these geologically informative lipids.

Synthesis of arborane triterpenols by a bacterial oxidosqualene cyclase

PubMed Central

Banta, Amy B.; Wei, Jeremy H.; Gill, Clare C. C.; Giner, José-Luis; Welander, Paula V.

2017-01-01

Cyclic triterpenoids are a broad class of polycyclic lipids produced by bacteria and eukaryotes. They are biologically relevant for their roles in cellular physiology, including membrane structure and function, and biochemically relevant for their exquisite enzymatic cyclization mechanism. Cyclic triterpenoids are also geobiologically significant as they are readily preserved in sediments and are used as biomarkers for ancient life throughout Earth's history. Isoarborinol is one such triterpenoid whose only known biological sources are certain angiosperms and whose diagenetic derivatives (arboranes) are often used as indicators of terrestrial input into aquatic environments. However, the occurrence of arborane biomarkers in Permian and Triassic sediments, which predates the accepted origin of angiosperms, suggests that microbial sources of these lipids may also exist. In this study, we identify two isoarborinol-like lipids, eudoraenol and adriaticol, produced by the aerobic marine heterotrophic bacterium Eudoraea adriatica. Phylogenetic analysis demonstrates that the E. adriatica eudoraenol synthase is an oxidosqualene cyclase homologous to bacterial lanosterol synthases and distinct from plant triterpenoid synthases. Using an Escherichia coli heterologous sterol expression system, we demonstrate that substitution of four amino acid residues in a bacterial lanosterol synthase enabled synthesis of pentacyclic arborinols in addition to tetracyclic sterols. This variant provides valuable mechanistic insight into triterpenoid synthesis and reveals diagnostic amino acid residues to differentiate between sterol and arborinol synthases in genomic and metagenomic datasets. Our data suggest that there may be additional bacterial arborinol producers in marine and freshwater environments that could expand our understanding of these geologically informative lipids. PMID:28028245

Cuphea: a new plant source of medium-chain fatty acids.

PubMed

Graham, S A

1989-01-01

The plant genus Cuphea (family Lythraceae) promises to provide a new source of industrially and nutritionally important medium-chain fatty acids, especially of lauric acid now supplied exclusively by coconut and palm kernel oils from foreign sources. The seed lipids of Cuphea were first discovered in the 1960s to contain high percentages of several medium-chain fatty acids, including caprylic, capric, lauric, and myristic acid. Research is still in the early stages, but it is intensifying toward the goal of developing the genus into a new temperate climate crop for production of specialty oils. Given the diversity of Cuphea seed lipid composition and the wide ecological and distributional range of the genus, it may be possible to tailor crops to produce selected fatty acids on demand under a variety of growing conditions. Cuphea comprises about 260 species, most native to the New World tropics. Its morphology, classification, chromosome numbers, distribution, ecology, and folk uses are presented. Seed structure is described and seed lipid composition for 73 species is summarized. Problems in domestication and agronomic progress are reviewed. Knowledge of the biosynthetic mechanism controlling the lipids produced by Cuphea remains very limited. Future research in this area, and particularly successful employment of gene transfer techniques, may allow genes controlling the mechanism to be transferred to an already established seed oil producer such as rapeseed. Presently, both traditional plant breeding techniques and newer biotechnological methods are directed toward Cuphea oilseed development.

Characterization of the lipid and protein organization in HBsAg viral particles by steady-state and time-resolved fluorescence spectroscopy.

PubMed

Greiner, Vanille J; Egelé, Caroline; Oncul, Sule; Ronzon, Frédéric; Manin, Catherine; Klymchenko, Andrey; Mély, Yves

2010-08-01

Hepatitis B surface antigen (HBsAg) particles, produced in the yeast Hansenula polymorpha, are 20 nm particles, composed of S surface viral proteins and host-derived lipids. Since the detailed structure of these particles is still missing, we further characterized them by fluorescence techniques. Fluorescence correlation spectroscopy indicated that the particles are mainly monomeric, with about 70 S proteins per particle. The S proteins were characterized through the intrinsic fluorescence of their thirteen Trp residues. Fluorescence quenching and time-resolved fluorescence experiments suggest the presence of both low emissive embedded Trp residues and more emissive Trp residues at the surface of the HBsAg particles. The low emission of the embedded Trp residues is consistent with their close proximity in alpha-helices. Furthermore, S proteins exhibit restricted movement, as expected from their tight association with lipids. The lipid organization of the particles was studied using viscosity-sensitive DPH-based probes and environment sensitive 3-hydroxyflavone probes, and compared to lipid vesicles and low density lipoproteins (LDLs), taken as models. Like LDLs, the HBsAg particles were found to be composed of an ordered rigid lipid interface, probably organized as a phospholipid monolayer, and a more hydrophobic and fluid inner core, likely composed of triglycerides and free fatty acids. However, the lipid core of HBsAg particles was substantially more polar than the LDL one, probably due to its larger content in proteins and its lower content in sterols. Based on our data, we propose a structural model for HBsAg particles where the S proteins deeply penetrate into the lipid core. Copyright 2010 Elsevier Masson SAS. All rights reserved.

Biosurfactants and surfactants interacting with membranes and proteins: Same but different?

PubMed

Otzen, Daniel E

2017-04-01

Biosurfactants (BS) are surface-active molecules produced by microorganisms. For several decades they have attracted interest as promising alternatives to current petroleum-based surfactants. Aside from their green profile, they have remarkably low critical micelle concentrations, reduce the air/water surface tension to very low levels and are excellent emulsifiers, all of which make them comparable or superior to their synthetic counterparts. These remarkable physical properties derive from their more complex chemical structures in which hydrophilic and hydrophobic regions are not as clearly separated as chemical surfactants but have a more mosaic distribution of polarity as well as branched or circular structures. This allows the lipopeptide surfactin to adopt spherical structures to facilitate dense packing at interfaces. They are also more complex. Glycolipid BS, e.g. rhamnolipids (RL) and sophorolipids, are produced biologically as mixtures which vary in the size and saturation of the hydrophobic region as well as modifications in the hydrophilic headgroup, such as the number of sugar groups and different levels of acetylation, leading to variable surface-active properties. Their amphiphilicity allows RL to insert easily into membranes at sub-cmc concentrations to modulate membrane structure and extract lipopolysaccharides, leading to extensive biofilm remodeling in vivo, sometimes in collaboration with hydrophobic RL precursors. Thanks to their mosaicity, even anionic BS like RL only bind weakly to proteins and show much lower denaturing potency, even supporting membrane protein refolding. Nevertheless, they can promote protein degradation by proteases e.g. by neutralizing positive charges, which together with their biofilm-combating properties makes them very promising detergent surfactants. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider. Copyright © 2016 Elsevier B.V. All rights reserved.

Lipases as biocatalysts for the synthesis of structured lipids.

PubMed

Jala, Ram Chandra Reddy; Hu, Peng; Yang, Tiankui; Jiang, Yuanrong; Zheng, Yan; Xu, Xuebing

2012-01-01

Structured lipids (SL) are broadly referred to as modified or synthetic oils and fats or lipids with functional or pharmaceutical applications. Some structured lipids, such as triglycerides that contain both long-chain (mainly essential) fatty acids and medium- or short-chain fatty acids and also artificial products that mimic the structure of natural materials, namely human milk fat substitutes and cocoa butter equivalents, have been discussed. Further, other modified or synthetic lipids, such as structured phospholipids and synthetic phenolic lipids are also included in this chapter. For all the products described in this chapter, enzymatic production in industry has been already conducted in one way or another. Cocoa butter equivalents, healthy oil containing medium-chain fatty acids, phosphatidyl serine, and phenol lipids from enzyme technology have been reported for commercial operation. As the demand for better quality functional lipids is increasing, the production of structured lipids becomes an interesting area. Thus, in this chapter we have discussed latest developments as well as present industrial situation of all commercially important structured lipids.

The effects of anesthetic agents on oxidative stress

NASA Astrophysics Data System (ADS)

Yakan, Selvinaz; Düzgüner, Vesile

2016-04-01

Oxidative stress can be defined as the instability between antioxidant defense of the body and the production of free radical that causes peroxydation on the lipid layer. Free radicals are reactive oxygen species that are produced in the course of normal metabolisms of aerobe organisms and they may cause disorders in cell structure and organelles by interacting macromolecules, like lipid, protein, nucleic acids. Therefore, they may cause cardiovascular, immune system, liver, kidney illnesses and many other illnesses like cancer, aging, cataract, diabetes. It is known that many drugs used for the purpose of anesthetizing may cause lipid peroxidation in organism. For these reasons, determining the Oxidative stress index of anaesthetic stress chosen in the ones that are exposed to long term anaesthetic agents and anaesthesia appliccations, is so substantial.

Micrometer-sized TPM emulsion droplets with surface-mobile binding groups

NASA Astrophysics Data System (ADS)

van der Wel, Casper; van de Stolpe, Guido L.; Verweij, Ruben W.; Kraft, Daniela J.

2018-03-01

Colloids coated with lipid membranes have been widely employed for fundamental studies of lipid membrane processes, biotechnological applications such as drug delivery and biosensing, and more recently, for self-assembly. The latter has been made possible by inserting DNA oligomers with covalently linked hydrophobic anchors into the membrane. The lateral mobility of the DNA linkers on micrometer-sized droplets and solid particles has opened the door to creating structures with unprecedented structural flexibility. Here, we investigate micro-emulsions of TPM (3-(trimethoxysilyl)propyl methacrylate) as a platform for lipid monolayers and further functionalization with proteins and DNA oligonucleotides. TPM droplets can be produced with a narrow size distribution and are polymerizable, thus providing supports for model lipid membranes with controlled size and curvature. With fluorescence recovery after photobleaching, we observed that droplet-attached lipids, NeutrAvidin proteins, as well as DNA oligonucleotides all show mobility on the surface. We explored the assembly of micron-sized particles on TPM-droplets by exploiting either avidin-biotin interactions or double-stranded DNA with complementary single-stranded end groups. While the single molecules are mobile, the particles that are attached to them are not. We propose that this is caused by the heterogeneous nature of emulsified TPM, which forms an oligomer network that limits the collective motion of linkers, but allows the surface mobility of individual molecules.

Synthetic surfactant- and cross-linker-free preparation of highly stable lipid-polymer hybrid nanoparticles as potential oral delivery vehicles.

PubMed

Wang, Taoran; Xue, Jingyi; Hu, Qiaobin; Zhou, Mingyong; Chang, Chao; Luo, Yangchao

2017-06-05

The toxicity associated with concentrated synthetic surfactants and the poor stability at gastrointestinal condition are two major constraints for practical applications of solid lipid nanoparticles (SLN) as oral delivery vehicles. In this study, a synthetic surfactant-free and cross-linker-free method was developed to fabricate effective, safe, and ultra-stable lipid-polymer hybrid nanoparticles (LPN). Bovine serum albumin (BSA) and dextran varying in molecular weights were first conjugated through Maillard reaction and the conjugates were exploited to emulsify solid lipid by a solvent diffusion and sonication method. The multilayer structure was formed by self-assembly of BSA-dextran micelles to envelope solid lipid via a pH- and heating-induced facile process with simultaneous surface deposition of pectin. The efficiency of different BSA-dextran conjugates was systematically studied to prepare LPN with the smallest size, the most homogeneous distribution and the greatest stability. The molecular interactions were characterized by Fourier transform infrared and fluorescence spectroscopies. Both nano spray drying and freeze-drying methods were tested to produce spherical and uniform pectin-coated LPN powders that were able to re-assemble nanoscale structure when redispersed in water. The results demonstrated the promise of a synthetic surfactant- and cross-linker-free technique to prepare highly stable pectin-coated LPN from all natural biomaterials as potential oral delivery vehicles.

Effect of mannosamine on the formation of lipid-linked oligosaccharides and glycoproteins in canine kidney cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Y.T.; Elbein, A.D.

1985-11-01

Madin-Darby canine kidney (MDCK) cells normally form lipid-linked oligosaccharides having mostly the Glc3Man9GlcNAc2 oligosaccharide. However, when MDCK cells are incubated in 1 to 10 mM mannosamine and labeled with (2-/sup 3/H)mannose, the major oligosaccharides associated with the dolichol were Man5GlcNAc2 and Man6GlcNAc2 structures. Since both of these oligosaccharides were susceptible to digestion by endo-beta-N-acetylglucosaminidase H, the Man5GlcNAc2 must be different in structure than the Man5GlcNAc2 usually found as a biosynthetic intermediate in the lipid-linked oligosaccharides. Since pulse chase studies indicated that the lesion was in biosynthesis, it appears that mannosamine inhibits the in vivo formation of lipid-linked oligosaccharides perhaps bymore » inhibiting the alpha-1,2-mannosyl transferases. Although the lipid-linked oligosaccharides produced in the presence of mannosamine were smaller in size than those of control cells and did not contain glucose, the oligosaccharides were still transferred in vivo to protein. Furthermore, the oligosaccharide portions of the glycoproteins were still processed as shown by the fact that the glycopeptides were of the complex and hybrid types and were labeled with (/sup 3/H)mannose or (/sup 3/H)galactose.« less

Bis-quaternary gemini surfactants as components of nonviral gene delivery systems: a comprehensive study from physicochemical properties to membrane interactions.

PubMed

Cardoso, Ana M; Morais, Catarina M; Silva, Sandra G; Marques, Eduardo F; de Lima, Maria C Pedroso; Jurado, Maria Amália S

2014-10-20

Gemini surfactants have been successfully used as components of gene delivery systems. In the present work, a family of gemini surfactants, represented by the general structure [CmH2m+1(CH3)2N(+)(CH2)sN(+)(CH3)2CmH2m+1]2Br(-), or simply m-s-m, was used to prepare cationic gene carriers, aiming at their application in transfection studies. An extensive characterization of the gemini surfactant-based complexes, produced with and without the helper lipids cholesterol and DOPE, was carried out in order to correlate their physico-chemical properties with transfection efficiency. The most efficient complexes were those containing helper lipids, which, combining amphiphiles with propensity to form structures with different intrinsic curvatures, displayed a morphologically labile architecture, putatively implicated in the efficient DNA release upon complex interaction with membranes. While complexes lacking helper lipids were translocated directly across the lipid bilayer, complexes containing helper lipids were taken up by cells also by macropinocytosis. This study contributes to shed light on the relationship between important physico-chemical properties of surfactant-based DNA vectors and their efficiency to promote gene transfer, which may represent a step forward to the rational design of gene delivery systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Production of membrane proteins without cells or detergents.

PubMed

Rajesh, Sundaresan; Knowles, Timothy; Overduin, Michael

2011-04-30

The production of membrane proteins in cellular systems is besieged by several problems due to their hydrophobic nature which often causes misfolding, protein aggregation and cytotoxicity, resulting in poor yields of stable proteins. Cell-free expression has emerged as one of the most versatile alternatives for circumventing these obstacles by producing membrane proteins directly into designed hydrophobic environments. Efficient optimisation of expression and solubilisation conditions using a variety of detergents, membrane mimetics and lipids has yielded structurally and functionally intact membrane proteins, with yields several fold above the levels possible from cell-based systems. Here we review recently developed techniques available to produce functional membrane proteins, and discuss amphipols, nanodisc and styrene maleic acid lipid particle (SMALP) technologies that can be exploited alongside cell-free expression of membrane proteins. Copyright © 2010 Elsevier B.V. All rights reserved.

One-Pot Parallel Synthesis of Lipid Library via Thiolactone Ring Opening and Screening for Gene Delivery.

PubMed

Molla, Mijanur R; Böser, Alexander; Rana, Akshita; Schwarz, Karina; Levkin, Pavel A

2018-04-18

Efficient delivery of nucleic acids into cells is of great interest in the field of cell biology and gene therapy. Despite a lot of research, transfection efficiency and structural diversity of gene-delivery vectors are still limited. A better understanding of the structure-function relationship of gene delivery vectors is also essential for the design of novel and intelligent delivery vectors, efficient in "difficult-to-transfect" cells and in vivo clinical applications. Most of the existing strategies for the synthesis of gene-delivery vectors require multiple steps and lengthy procedures. Here, we demonstrate a facile, three-component one-pot synthesis of a combinatorial library of 288 structurally diverse lipid-like molecules termed "lipidoids" via a thiolactone ring opening reaction. This strategy introduces the possibility to synthesize lipidoids with hydrophobic tails containing both unsaturated bonds and reducible disulfide groups. The whole synthesis and purification are convenient, extremely fast, and can be accomplished within a few hours. Screening of the produced lipidoids using HEK293T cells without addition of helper lipids resulted in identification of highly stable liposomes demonstrating ∼95% transfection efficiency with low toxicity.

An Unlikely Silk: The Composite Material of Green Lacewing Cocoons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weisman, Sarah; Trueman, Holly E.; Mudie, Stephen T.

2009-01-15

Spiders routinely produce multiple types of silk; however, common wisdom has held that insect species produce one type of silk each. This work reports that the green lacewing (Mallada signata, Neuroptera) produces two distinct classes of silk. We identified and sequenced the gene that encodes the major protein component of the larval lacewing cocoon silk and demonstrated that it is unrelated to the adult lacewing egg-stalk silk. The cocoon silk protein is 49 kDa in size and is alanine rich (>40%), and it contains an {alpha}-helical secondary structure. The final instar lacewing larvae spin protein fibers of {approx}2 {mu}m diametermore » to construct a loosely woven cocoon. In a second stage of cocoon construction, the insects lay down an inner wall of lipids that uses the fibers as a scaffold. We propose that the silk protein fibers provide the mechanical strength of the composite lacewing cocoon whereas the lipid layer provides a barrier to water loss during pupation.« less

Integrity of erythrocytes of hypercholesterolemic rats during spices treatment.

PubMed

Kempaiah, R K; Srinivasan, K

2002-07-01

In rats rendered hypercholesterolemic by maintaining them on a cholesterol-enriched diet (0.5%) for 8 weeks, inclusion of spice principles--curcumin (0.2%) or capsaicin (0.015%) or the spice--garlic powder (2.0%) in the diet, produced the expected hypolipidemic effect. Plasma cholesterol which was more than 200% that of basal control in hypercholesterolemic rats, was decreased by these dietary spice principles and garlic by 25-39%. Erythrocyte membranes of hypercholesterolemic rats were relatively enriched in cholesterol, which was about 120% of basal control, while membrane phospholipid was unaffected. This resulted in a significant alteration in cholesterol to phospholipid ratio of RBC membranes. Dietary curcumin, capsaicin and garlic were observed to counter this altered lipid profile of erythrocyte membranes in hypercholesterolemic situation by producing a significant 10-14% decrease in membrane cholesterol content. As a result of alteration in membrane structural lipids, the structural integrity of RBCs was also affected. An examination of the osmotic fragility of erythrocytes in various groups, indicated that RBCs of hypercholesterolemic rats were relatively fragile compared to normal controls. Dietary curcumin, capsaicin and garlic appeared to correct this increased fragility of erythrocytes.

N,N-diethyldithiocarbamate promotes oxidative stress prior to myelin structural changes and increases myelin copper content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viquez, Olga M.; Lai, Barry; Ahn, Jae Hee

2009-08-15

Dithiocarbamates are a commercially important class of compounds that can produce peripheral neuropathy in humans and experimental animals. Previous studies have supported a requirement for copper accumulation and enhanced lipid peroxidation in dithiocarbamate-mediated myelinopathy. The study presented here extends previous investigations in two areas. Firstly, although total copper levels have been shown to increase within the nerve it has not been determined whether copper is increased within the myelin compartment, the primary site of lesion development. Therefore, the distribution of copper in sciatic nerve was characterized using synchrotron X-ray fluorescence microscopy to determine whether the neurotoxic dithiocarbamate, N,N-diethyldithiocarbamate, increases coppermore » levels in myelin. Secondly, because lipid peroxidation is an ongoing process in normal nerve and the levels of lipid peroxidation products produced by dithiocarbamate exposure demonstrated an unusual cumulative dose response in previous studies the biological impact of dithiocarbamate-mediated lipid peroxidation was evaluated. Experiments were performed to determine whether dithiocarbamate-mediated lipid peroxidation products elicit an antioxidant response through measuring the protein expression levels of three enzymes, superoxide dismutase 1, heme oxygenase 1, and glutathione transferase {alpha}, that are linked to the antioxidant response element promoter. To establish the potential of oxidative injury to contribute to myelin injury the temporal relationship of the antioxidant response to myelin injury was determined. Myelin structure in peripheral nerve was assessed using multi-exponential transverse relaxation measurements (MET{sub 2}) as a function of exposure duration, and the temporal relationship of protein expression changes relative to the onset of changes in myelin integrity were determined. Initial assessments were also performed to explore the potential contribution of dithiocarbamate-mediated inhibition of proteasome function and inhibition of cuproenzyme activity to neurotoxicity, and also to assess the potential of dithiocarbamates to promote oxidative stress and injury within the central nervous system. These evaluations were performed using an established model for dithiocarbamate-mediated demyelination in the rat utilizing sciatic nerve, spinal cord and brain samples obtained from rats exposed to N,N-diethyldithiocarbamate (DEDC) by intra-abdominal pumps for periods of 2, 4, and 8 weeks and from non exposed controls. The data supported the ability of DEDC to increase copper within myelin and to enhance oxidative stress prior to structural changes detectable by MET{sub 2}. Evidence was also obtained that the excess copper produced by DEDC in the central nervous system is redox active and promotes oxidative injury.« less

Liposomes in tissue engineering and regenerative medicine

PubMed Central

Monteiro, Nelson; Martins, Albino; Reis, Rui L.; Neves, Nuno M.

2014-01-01

Liposomes are vesicular structures made of lipids that are formed in aqueous solutions. Structurally, they resemble the lipid membrane of living cells. Therefore, they have been widely investigated, since the 1960s, as models to study the cell membrane, and as carriers for protection and/or delivery of bioactive agents. They have been used in different areas of research including vaccines, imaging, applications in cosmetics and tissue engineering. Tissue engineering is defined as a strategy for promoting the regeneration of tissues for the human body. This strategy may involve the coordinated application of defined cell types with structured biomaterial scaffolds to produce living structures. To create a new tissue, based on this strategy, a controlled stimulation of cultured cells is needed, through a systematic combination of bioactive agents and mechanical signals. In this review, we highlight the potential role of liposomes as a platform for the sustained and local delivery of bioactive agents for tissue engineering and regenerative medicine approaches. PMID:25401172

Role of Gag and lipids during HIV-1 assembly in CD4+ T cells and macrophages

PubMed Central

Mariani, Charlotte; Desdouits, Marion; Favard, Cyril; Benaroch, Philippe; Muriaux, Delphine M.

2014-01-01

HIV-1 is an RNA enveloped virus that preferentially infects CD4+ T lymphocytes and also macrophages. In CD4+ T cells, HIV-1 mainly buds from the host cell plasma membrane. The viral Gag polyprotein targets the plasma membrane and is the orchestrator of the HIV assembly as its expression is sufficient to promote the formation of virus-like particles carrying a lipidic envelope derived from the host cell membrane. Certain lipids are enriched in the viral membrane and are thought to play a key role in the assembly process and the envelop composition. A large body of work performed on infected CD4+ T cells has provided important knowledge about the assembly process and the membrane virus lipid composition. While HIV assembly and budding in macrophages is thought to follow the same general Gag-driven mechanism as in T-lymphocytes, the HIV cycle in macrophage exhibits specific features. In these cells, new virions bud from the limiting membrane of seemingly intracellular compartments, where they accumulate while remaining infectious. These structures are now often referred to as Virus Containing Compartments (VCCs). Recent studies suggest that VCCs represent intracellularly sequestered regions of the plasma membrane, but their precise nature remains elusive. The proteomic and lipidomic characterization of virions produced by T cells or macrophages has highlighted the similarity between their composition and that of the plasma membrane of producer cells, as well as their enrichment in acidic lipids, some components of raft lipids and in tetraspanin-enriched microdomains. It is likely that Gag promotes the coalescence of these components into an assembly platform from which viral budding takes place. How Gag exactly interacts with membrane lipids and what are the mechanisms involved in the interaction between the different membrane nanodomains within the assembly platform remains unclear. Here we review recent literature regarding the role of Gag and lipids on HIV-1 assembly in CD4+ T cells and macrophages. PMID:25009540

Role of Components in the Formation of Self-microemulsifying Drug Delivery Systems.

PubMed

Gurram, A K; Deshpande, P B; Kar, S S; Nayak, Usha Y; Udupa, N; Reddy, M S

2015-01-01

Pharmaceutical research is focused in designing novel drug delivery systems to improve the bioavailability of poorly water soluble drugs. Self-microemulsifying drug delivery systems, one among the lipid-based dosage forms were proven to be promising in improving the oral bioavailability of such drugs by enhancing solubility, permeability and avoiding first-pass metabolism via enhanced lymphatic transport. Further, they have been successful in avoiding both inter and intra individual variations as well as the dose disproportionality. Aqueous insoluble drugs, in general, show greater solubility in lipid based excipients, and hence they are formulated as lipid based drug delivery systems. The extent of solubility of a hydrophobic drug in lipid excipients i.e. oil, surfactant and co-surfactant (components of self-microemulsifying drug delivery systems) greatly affects the drug loading and in producing stable self-microemulsifying drug delivery systems. The present review highlighted the influence of physicochemical factors and structural features of the hydrophobic drug on its solubility in lipid excipients and an attempt was made to explore the role of each component of self-microemulsifying drug delivery systems in the formation of stable microemulsion upon dilution.

Amino Acid Degradations Produced by Lipid Oxidation Products.

PubMed

Hidalgo, Francisco J; Zamora, Rosario

2016-06-10

Differently to amino acid degradations produced by carbohydrate-derived reactive carbonyls, amino acid degradations produced by lipid oxidation products are lesser known in spite of being lipid oxidation a major source of reactive carbonyls in food. This article analyzes the conversion of amino acids into Strecker aldehydes, α-keto acids, and amines produced by lipid-derived free radicals and carbonyl compounds, as well as the role of lipid oxidation products on the reactions suffered by these compounds: the formation of Strecker aldehydes and other aldehydes from α-keto acids; the formation of Strecker aldehydes and olefins from amines; the formation of shorter aldehydes from Strecker aldehydes; and the addition reactions suffered by the olefins produced from the amines. The relationships among all these reactions and the effect of reaction conditions on them are discussed. This knowledge should contribute to better control food processing in order to favor the formation of desirable beneficial compounds and to inhibit the production of compounds with deleterious properties.

Abundant Type III Lipid Transfer Proteins in Arabidopsis Tapetum Are Secreted to the Locule and Become a Constituent of the Pollen Exine1[W][OPEN

PubMed Central

Huang, Ming-Der; Chen, Tung-Ling L.; Huang, Anthony H.C.

2013-01-01

Lipid transfer proteins (LTPs) are small secretory proteins in plants with defined lipid-binding structures for possible lipid exocytosis. Special groups of LTPs unique to the anther tapetum are abundant, but their functions are unclear. We studied a special group of LTPs, type III LTPs, in Arabidopsis (Arabidopsis thaliana). Their transcripts were restricted to the anther tapetum, with levels peaking at the developmental stage of maximal pollen-wall exine synthesis. We constructed an LTP-Green Fluorescent Protein (LTP-GFP) plasmid, transformed it into wild-type plants, and monitored LTP-GFP in developing anthers with confocal laser scanning microscopy. LTP-GFP appeared in the tapetum and was secreted via the endoplasmic reticulum-trans-Golgi network machinery into the locule. It then moved to the microspore surface and remained as a component of exine. Immuno-transmission electron microscopy of native LTP in anthers confirmed the LTP-GFP observations. The in vivo association of LTP-GFP and exine in anthers was not observed with non-type III or structurally modified type III LTPs or in transformed exine-defective mutant plants. RNA interference knockdown of individual type III LTPs produced no observable mutant phenotypes. RNA interference knockdown of two type III LTPs produced microscopy-observable morphologic changes in the intine underneath the exine (presumably as a consequence of changes in the exine not observed by transmission electron microscopy) and pollen susceptible to dehydration damage. Overall, we reveal a novel transfer pathway of LTPs in which LTPs bound or nonbound to exine precursors are secreted from the tapetum to become microspore exine constituents; this pathway explains the need for plentiful LTPs to incorporate into the abundant exine. PMID:24096413

Distribution of health-related social surplus in pharmaceuticals: an estimation of consumer and producer surplus in the management of high blood lipids and COPD.

PubMed

Refoios Camejo, Rodrigo; Camejo, Rodrigo Refoios; McGrath, Clare; Miraldo, Marisa; Rutten, Frans

2014-05-01

Following suggestions that developers should be allowed to capture a defined share of the total value generated by their technologies, the amount of surplus accruing to the pharmaceutical industry has become an important concept when discussing policies to encourage innovation in healthcare. Observational clinical and market data spanning over a period of 20 years were applied in order to estimate the social surplus generated by pharmaceuticals used in the management of high cholesterol and chronic obstructive pulmonary disease (COPD). The distribution of social surplus between consumers and producers was also computed and the dynamics of rent extraction examined. Health-related social surplus increased consistently over time for both disease areas, mostly due to the launch of more effective technologies and a greater number of patients being treated for the conditions. However, the growth rate of social surplus differed for each disease and dissimilar patterns of distribution between consumer and producer surplus emerged across the years. For lipid-lowering therapies, yearly consumer surplus reaches 85 % of total health-related social surplus after the loss of exclusivity of major molecules, whilst for COPD it ranges from 54 to 69 %. Average producer surplus is approximately 25 % of total health-related social surplus in the lipid-lowering market between 1990 and 2010, and 37 % for COPD between 2001 and 2010. The share of surplus captured by non-innovative generic producers also varies differently across periods for both markets, reaching 11.12 % in the case of lipid-lowering therapies but just 1.55 % in the case of COPD. A considerable amount of the value may be recouped by consumers only towards the end of the lifecycle. Elements affecting the distribution of social surplus vary across disease areas and include the market pricing structure and the pattern of clinical effectiveness observed over time. The application of a longer-term disease specific perspective may be required when assessing the cost-effectiveness of health technologies at launch.

Acyl-Lipid Metabolism

PubMed Central

Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X.; Arondel, Vincent; Bates, Philip D.; Baud, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

2013-01-01

Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:23505340

Acyl-Lipid Metabolism

PubMed Central

Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X.; Arondel, Vincent; Bates, Philip D.; Baud, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

2010-01-01

Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:22303259

Monitoring Interfacial Lipid Oxidation in Oil-in-Water Emulsions Using Spatially Resolved Optical Techniques.

PubMed

Banerjee, Chiranjib; Westberg, Michael; Breitenbach, Thomas; Bregnhøj, Mikkel; Ogilby, Peter R

2017-06-06

The oxidation of lipids is an important phenomenon with ramifications for disciplines that range from food science to cell biology. The development and characterization of tools and techniques to monitor lipid oxidation are thus relevant. Of particular significance in this regard are tools that facilitate the study of oxidations at interfaces in heterogeneous samples (e.g., oil-in-water emulsions, cell membranes). In this article, we establish a proof-of-principle for methods to initiate and then monitor such oxidations with high spatial resolution. The experiments were performed using oil-in-water emulsions of polyunsaturated fatty acids (PUFAs) prepared from cod liver oil. We produced singlet oxygen at a point near the oil-water interface of a given PUFA droplet in a spatially localized two-photon photosensitized process. We then followed the oxidation reactions initiated by this process with the fluorescence-based imaging technique of structured illumination microscopy (SIM). We conclude that the approach reported herein has attributes well-suited to the study of lipid oxidation in heterogeneous samples.

Cell-wall disruption and lipid/astaxanthin extraction from microalgae: Chlorella and Haematococcus.

PubMed

Kim, Dong-Yeon; Vijayan, Durairaj; Praveenkumar, Ramasamy; Han, Jong-In; Lee, Kyubock; Park, Ji-Yeon; Chang, Won-Seok; Lee, Jin-Suk; Oh, You-Kwan

2016-01-01

Recently, biofuels and nutraceuticals produced from microalgae have emerged as major interests, resulting in intensive research of the microalgal biorefinery process. In this paper, recent developments in cell-wall disruption and extraction methods are reviewed, focusing on lipid and astaxanthin production from the biotechnologically important microalgae Chlorella and Haematococcus, respectively. As a common, critical bottleneck for recovery of intracellular components such as lipid and astaxanthin from these microalgae, the composition and structure of rigid, thick cell-walls were analyzed. Various chemical, physical, physico-chemical, and biological methods applied for cell-wall breakage and lipid/astaxanthin extraction from Chlorella and Haematococcus are discussed in detail and compared based on efficiency, energy consumption, type and dosage of solvent, biomass concentration and status (wet/dried), toxicity, scalability, and synergistic combinations. This report could serve as a useful guide to the implementation of practical downstream processes for recovery of valuable products from microalgae including Chlorella and Haematococcus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Combinatorial pretreatment and fermentation optimization enabled a record yield on lignin bioconversion.

PubMed

Liu, Zhi-Hua; Xie, Shangxian; Lin, Furong; Jin, Mingjie; Yuan, Joshua S

2018-01-01

Lignin valorization has recently been considered to be an essential process for sustainable and cost-effective biorefineries. Lignin represents a potential new feedstock for value-added products. Oleaginous bacteria such as Rhodococcus opacus can produce intracellular lipids from biodegradation of aromatic substrates. These lipids can be used for biofuel production, which can potentially replace petroleum-derived chemicals. However, the low reactivity of lignin produced from pretreatment and the underdeveloped fermentation technology hindered lignin bioconversion to lipids. In this study, combinatorial pretreatment with an optimized fermentation strategy was evaluated to improve lignin valorization into lipids using R. opacus PD630. As opposed to single pretreatment, combinatorial pretreatment produced a 12.8-75.6% higher lipid concentration in fermentation using lignin as the carbon source. Gas chromatography-mass spectrometry analysis showed that combinatorial pretreatment released more aromatic monomers, which could be more readily utilized by lignin-degrading strains. Three detoxification strategies were used to remove potential inhibitors produced from pretreatment. After heating detoxification of the lignin stream, the lipid concentration further increased by 2.9-9.7%. Different fermentation strategies were evaluated in scale-up lipid fermentation using a 2.0-l fermenter. With laccase treatment of the lignin stream produced from combinatorial pretreatment, the highest cell dry weight and lipid concentration were 10.1 and 1.83 g/l, respectively, in fed-batch fermentation, with a total soluble substrate concentration of 40 g/l. The improvement of the lipid fermentation performance may have resulted from lignin depolymerization by the combinatorial pretreatment and laccase treatment, reduced inhibition effects by fed-batch fermentation, adequate oxygen supply, and an accurate pH control in the fermenter. Overall, these results demonstrate that combinatorial pretreatment, together with fermentation optimization, favorably improves lipid production using lignin as the carbon source. Combinatorial pretreatment integrated with fed-batch fermentation was an effective strategy to improve the bioconversion of lignin into lipids, thus facilitating lignin valorization in biorefineries.

Alteration processes of alkenones and related lipids in water columns and sediments

NASA Astrophysics Data System (ADS)

Harvey, H. Rodger

2000-08-01

Alkenones produced by the haptophyte algae are currently being used as indices of sea surface temperature in recent and past ocean environments, but limited information is available concerning the impact of biotic and abiotic processes on the integrity of these long chain lipids. This synthesis provides selected background information on major alteration processes that must be considered before such indices can be used with confidence. A number of processes in the water column and surface sediments have the potential to impact the structural integrity of alkenones and compromise their ability as temperature markers. Processes discussed include the alteration of alkenone structure during early diagenesis, direct biotic and abiotic impacts, and the effect of digestive processes by grazers. Current literature suggests that despite substantial changes in concentration from biological processing, the temperature signal is preserved. For each of these processes, information on the integrity of the alkenone isotopic signature is also needed and limited information available is reviewed. In addition to the alkenones, related lipids including the long chain alkadienes and akyl alkenoates that might serve as ancillary markers are discussed.

Time to face the fats: what can mass spectrometry reveal about the structure of lipids and their interactions with proteins?

PubMed

Brown, Simon H J; Mitchell, Todd W; Oakley, Aaron J; Pham, Huong T; Blanksby, Stephen J

2012-09-01

Since the 1950s, X-ray crystallography has been the mainstay of structural biology, providing detailed atomic-level structures that continue to revolutionize our understanding of protein function. From recent advances in this discipline, a picture has emerged of intimate and specific interactions between lipids and proteins that has driven renewed interest in the structure of lipids themselves and raised intriguing questions as to the specificity and stoichiometry in lipid-protein complexes. Herein we demonstrate some of the limitations of crystallography in resolving critical structural features of ligated lipids and thus determining how these motifs impact protein binding. As a consequence, mass spectrometry must play an important and complementary role in unraveling the complexities of lipid-protein interactions. We evaluate recent advances and highlight ongoing challenges towards the twin goals of (1) complete structure elucidation of low, abundant, and structurally diverse lipids by mass spectrometry alone, and (2) assignment of stoichiometry and specificity of lipid interactions within protein complexes.

Time to Face the Fats: What Can Mass Spectrometry Reveal about the Structure of Lipids and Their Interactions with Proteins?

NASA Astrophysics Data System (ADS)

Brown, Simon H. J.; Mitchell, Todd W.; Oakley, Aaron J.; Pham, Huong T.; Blanksby, Stephen J.

2012-09-01

Since the 1950s, X-ray crystallography has been the mainstay of structural biology, providing detailed atomic-level structures that continue to revolutionize our understanding of protein function. From recent advances in this discipline, a picture has emerged of intimate and specific interactions between lipids and proteins that has driven renewed interest in the structure of lipids themselves and raised intriguing questions as to the specificity and stoichiometry in lipid-protein complexes. Herein we demonstrate some of the limitations of crystallography in resolving critical structural features of ligated lipids and thus determining how these motifs impact protein binding. As a consequence, mass spectrometry must play an important and complementary role in unraveling the complexities of lipid-protein interactions. We evaluate recent advances and highlight ongoing challenges towards the twin goals of (1) complete structure elucidation of low, abundant, and structurally diverse lipids by mass spectrometry alone, and (2) assignment of stoichiometry and specificity of lipid interactions within protein complexes.

Sphingolipids from the human fungal pathogen Aspergillus fumigatus.

PubMed

Fontaine, Thierry

2017-10-01

Sphingolipids (SPLs) are key components of the plasma membrane in yeast and filamentous fungi. These molecules are involved in a number of cellular processes, and particularly, SGLs are essential components of the highly polarized fungal growth where they are required for the formation of the polarisome organization at the hyphal apex. Aspergillus fumigatus, a human fungal pathogen, produce SGLs that are discriminated into neutral cerebrosides, glycosylinositolphosphoceramides (GIPCs) and glycosylphosphatidylinositol (GPI) anchors. In addition to complex hydrophilic head groups of GIPCs, A. fumigatus is, to date, the sole fungus that produces a GPI-anchored polysaccharide. These SPLs follow three different biosynthetic pathways. Genetics blockage leading to the inhibition of any SPL biosynthesis or to the alteration of the structure of SPL induces growth and virulence defects. The complete lipid moiety of SPLs is essential for the lipid microdomain organization and their biosynthetic pathways are potential antifungal targets but remains understudied. Copyright © 2017. Published by Elsevier B.V.

Effect of Variable Solvents on Particle Size of Geranium Oil-Loaded Solid Lipid Nanoparticle (Ge-SLN) For Mosquito Repellent Applications

NASA Astrophysics Data System (ADS)

Asnawi, Syalwati; Aziz, Azila A.; Aziz, Ramlan A.

2009-06-01

A new delivery system for insect repellent is proposed by the incorporation of geranium oil into solid lipid nanoparticle (SLN). A variety of solvents which act as co-surfactants, were introduced to increase the particle size of GE-SLN. Ethanol, which has a high boiling point and a long chain alcohol produced larger particle than dichloromethane. The structure of SLN was not stable when methanol and acetone were used as co-solvents. Concentration of solvents can also influence the size of SLN. In vitro release experiments showed that SLN was able to reduce the rapid evaporation of geranium oil.

Early Stages of Oxidative Stress-Induced Membrane Permeabilization: A Neutron Reflectometry Study

PubMed Central

Smith, Hillary L.; Howland, Michael C.; Szmodis, Alan W.; Li, Qijuan; Daemen, Luke L.; Parikh, Atul N.; Majewski, Jaroslaw

2009-01-01

Neutron reflectometry was used to probe in situ the structure of supported lipid bilayers at the solid–liquid interface during the early stages of UV-induced oxidative degradation. Single-component supported lipid bilayers composed of gel phase, dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and fluid phase, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), phospholipids were exposed to low-dose oxidative stress generated by UV light and their structures were examined by neutron reflectometry. An interrupted illumination mode, involving exposures in 15 min increments with 2 h intervals between subsequent exposures, and a continuous mode involving a single 60 (or 90) min exposure period were employed. In both cases, pronounced differences in the structure of the lipid bilayer after exposure were observed. Interrupted exposure led to a substantial decrease in membrane coverage but preserved its total thickness at reduced scattering length densities. These results indicate that the initial phase during UV-induced membrane degradation involves the formation of hydrophilic channels within the membrane. This is consistent with the loss of some lipid molecules we observe and attendant reorganization of residual lipids forming hemimicellar edges of the hydrophilic channels. In contrast, continuous illumination produced a graded interface of continuously varied scattering length density (and hence hydrocarbon density) extending 100–150 Å into the liquid phase. Exposure of a DPPC bilayer to UV light in the presence of a reservoir of unfused vesicles showed low net membrane disintegration during oxidative stress, presumably because of surface back-filling from the bulk reservoir. Chemical evidence for membrane degradation was obtained by mass spectrometry and Fourier transform infrared spectroscopy. Further evidence for the formation of hydrophilic channels was furnished by fluorescence microscopy and imaging ellipsometry data. PMID:19275260

Yeast lipids from cardoon stalks, stranded driftwood and olive tree pruning residues as possible extra sources of oils for producing biofuels and biochemicals.

PubMed

Tasselli, Giorgia; Filippucci, Sara; Borsella, Elisabetta; D'Antonio, Silvia; Gelosia, Mattia; Cavalaglio, Gianluca; Turchetti, Benedetta; Sannino, Ciro; Onofri, Andrea; Mastrolitti, Silvio; De Bari, Isabella; Cotana, Franco; Buzzini, Pietro

2018-01-01

Some lignocellulosic biomass feedstocks occur in Mediterranean Countries. They are still largely unexploited and cause considerable problems due to the lack of cost-effective harvesting, storage and disposal technologies. Recent studies found that some basidiomycetous yeasts are able to accumulate high amount of intracellular lipids for biorefinery processes (i.e., biofuels and biochemicals). Accordingly, the above biomass feedstocks could be used as carbon sources (after their pre-treatment and hydrolysis) for lipid accumulation by oleaginous yeasts. Cardoon stalks, stranded driftwood and olive tree pruning residues were pre-treated with steam-explosion and enzymatic hydrolysis for releasing free mono- and oligosaccharides. Lipid accumulation tests were performed at two temperatures (20 and 25 °C) using Leucosporidium creatinivorum DBVPG 4794, Naganishia adeliensis DBVPG 5195 and Solicoccozyma terricola DBVPG 5870. S. terricola grown on cardoon stalks at 20 °C exhibited the highest lipid production (13.20 g/l), a lipid yield (28.95%) close to the maximum theoretical value and a lipid composition similar to that found in palm oil. On the contrary, N. adeliensis grown on stranded driftwood and olive tree pruning residues exhibited a lipid composition similar to those of olive and almonds oils. A predictive evaluation of the physical properties of the potential biodiesel obtainable by lipids produced by tested yeast strains has been reported and discussed. Lipids produced by some basidiomycetous yeasts grown on Mediterranean lignocellulosic biomass feedstocks could be used as supplementary sources of oils for producing biofuels and biochemicals.

Gravimetric enrichment of high lipid and starch accumulating microalgae.

PubMed

Hassanpour, Morteza; Abbasabadi, Mahsa; Ebrahimi, Sirous; Hosseini, Maryam; Sheikhbaglou, Ahmad

2015-11-01

This study presents gravimetric enrichment of mixed culture to screen starch and lipid producing species separately in a sequencing batch reactor. In the enriched starch-producing mixed culture photobioreactor, the starch content at the end of steady state batch became 3.42 times the beginning of depletion. Whereas in the enriched lipid-producing photobioreactor, the lipid content at the end of steady state batch became 3 times the beginning of famine phase. The obtained results revealed that the gravimetric enrichment is a suitable screening method for specific production of storage compounds in none-sterile large-scaled condition. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bromelain-Functionalized Multiple-Wall Lipid-Core Nanocapsules: Formulation, Chemical Structure and Antiproliferative Effect Against Human Breast Cancer Cells (MCF-7).

PubMed

Oliveira, Catiúscia P; Prado, Willian A; Lavayen, Vladimir; Büttenbender, Sabrina L; Beckenkamp, Aline; Martins, Bruna S; Lüdtke, Diogo S; Campo, Leandra F; Rodembusch, Fabiano S; Buffon, Andréia; Pessoa, Adalberto; Guterres, Silvia S; Pohlmann, Adriana R

2017-02-01

This study was conducted a promising approach to surface functionalization developed for lipid-core nanocapsules and the merit to pursue new strategies to treat solid tumors. Bromelain-functionalized multiple-wall lipid-core nanocapsules (Bro-MLNC-Zn) were produced by self-assembling following three steps of interfacial reactions. Physicochemical and structural characteristics, in vitro proteolytic activity (casein substrate) and antiproliferative activity (breast cancer cells, MCF-7) were determined. Bro-MLNC-Zn had z-average diameter of 135 nm and zeta potential of +23 mV. The complex is formed by a Zn-N chemical bond and a chelate with hydroxyl and carboxyl groups. Bromelain complexed at the nanocapsule surface maintained its proteolytic activity and showed anti-proliferative effect against human breast cancer cells (MCF-7) (72.6 ± 1.2% at 1.250 μg mL -1 and 65.5 ± 5.5% at 0.625 μg mL -1 ). Comparing Bro-MLNC-Zn and bromelain solution, the former needed a dose 160-folds lower than the latter for a similar effect. Tripan blue dye assay corroborated the results. The surface functionalization approach produced an innovative formulation having a much higher anti-proliferative effect than the bromelain solution, even though both in vitro proteolytic activity were similar, opening up a great opportunity for further studies in nanomedicine.

Enhanced dissolved lipid production as a response to the sea surface warming

NASA Astrophysics Data System (ADS)

Novak, Tihana; Godrijan, Jelena; Pfannkuchen, Daniela Marić; Djakovac, Tamara; Mlakar, Marina; Baricevic, Ana; Tanković, Mirta Smodlaka; Gašparović, Blaženka

2018-04-01

The temperature increase in oceans reflects on marine ecosystem functioning and surely has consequences on the marine carbon cycle and carbon sequestration. In this study, we examined dissolved lipid, lipid classes and dissolved organic carbon (DOC) production in the northern Adriatic Sea, isolated diatom Chaetoceros pseudocurvisetus batch cultures grown in a wide temperature range (10-30 °C) and in contrasting nutrient regimes, phosphorus (P)-depleted and P-replete conditions. Additionally, lipids and DOC were analyzed in the northern Adriatic (NA) in two stations characterized with different P availability, occupied from February to August 2010 that covered a temperature range from 9.3 to 31.1 °C. To gain insight into factors governing lipid and lipid classes' production in the NA, apart from temperature (T), Chlorophyll a, phytoplankton community abundance and structure, nutrient concentrations were measured together with hydrographic parameters. We found enhanced accumulation of dissolved lipids, particulary glycolipids, with increasing T, especially during the highest in situ temperature. The effect of T on enhanced dissolved lipid release is much more pronounced under P-deplete conditions indicating that oligotrophic regions might be more vulnerable to T rise. Temperature between 25 and 30 °C is a threshold T range for C. pseudocurvisetus, at which a significant part of lipid production is directed toward the dissolved phase. Unlike monocultures, there are multiple factors influencing produced lipid composition, distribution and cycling in the NA that may counteract the T influence. The possible role of enhanced dissolved lipid concentration for carbon sequestration at elevated T is discussed. On the one hand, lipids are buoyant and do not sink, which enhances their retention at the surface layer. In addition, they are surface active, and therefore prone to adsorb on sinking particles, contributing to the C sequestration.

Progesterone lipid nanoparticles: Scaling up and in vivo human study.

PubMed

Esposito, Elisabetta; Sguizzato, Maddalena; Drechsler, Markus; Mariani, Paolo; Carducci, Federica; Nastruzzi, Claudio; Cortesi, Rita

2017-10-01

This investigation describes a scaling up study aimed at producing progesterone containing nanoparticles in a pilot scale. Particularly hot homogenization techniques based on ultrasound homogenization or high pressure homogenization have been employed to produce lipid nanoparticles constituted of tristearin or tristearin in association with caprylic-capric triglyceride. It was found that the high pressure homogenization method enabled to obtain nanoparticles without agglomerates and smaller mean diameters with respect to ultrasound homogenization method. X-ray characterization suggested a lamellar structural organization of both type of nanoparticles. Progesterone encapsulation efficiency was almost 100% in the case of high pressure homogenization method. Shelf life study indicated a double fold stability of progesterone when encapsulated in nanoparticles produced by the high pressure homogenization method. Dialysis and Franz cell methods were performed to mimic subcutaneous and skin administration. Nanoparticles constituted of tristearin in mixture with caprylic/capric triglyceride display a slower release of progesterone with respect to nanoparticles constituted of pure tristearin. Franz cell evidenced a higher progesterone skin uptake in the case of pure tristearin nanoparticles. A human in vivo study, based on tape stripping, was conducted to investigate the performance of nanoparticles as progesterone skin delivery systems. Tape stripping results indicated a decrease of progesterone concentration in stratum corneum within six hours, suggesting an interaction between nanoparticle material and skin lipids. Copyright © 2017 Elsevier B.V. All rights reserved.

The SwissLipids knowledgebase for lipid biology

PubMed Central

Liechti, Robin; Hyka-Nouspikel, Nevila; Niknejad, Anne; Gleizes, Anne; Götz, Lou; Kuznetsov, Dmitry; David, Fabrice P.A.; van der Goot, F. Gisou; Riezman, Howard; Bougueleret, Lydie; Xenarios, Ioannis; Bridge, Alan

2015-01-01

Motivation: Lipids are a large and diverse group of biological molecules with roles in membrane formation, energy storage and signaling. Cellular lipidomes may contain tens of thousands of structures, a staggering degree of complexity whose significance is not yet fully understood. High-throughput mass spectrometry-based platforms provide a means to study this complexity, but the interpretation of lipidomic data and its integration with prior knowledge of lipid biology suffers from a lack of appropriate tools to manage the data and extract knowledge from it. Results: To facilitate the description and exploration of lipidomic data and its integration with prior biological knowledge, we have developed a knowledge resource for lipids and their biology—SwissLipids. SwissLipids provides curated knowledge of lipid structures and metabolism which is used to generate an in silico library of feasible lipid structures. These are arranged in a hierarchical classification that links mass spectrometry analytical outputs to all possible lipid structures, metabolic reactions and enzymes. SwissLipids provides a reference namespace for lipidomic data publication, data exploration and hypothesis generation. The current version of SwissLipids includes over 244 000 known and theoretically possible lipid structures, over 800 proteins, and curated links to published knowledge from over 620 peer-reviewed publications. We are continually updating the SwissLipids hierarchy with new lipid categories and new expert curated knowledge. Availability: SwissLipids is freely available at http://www.swisslipids.org/. Contact: alan.bridge@isb-sib.ch Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25943471

Influence of encapsulated functional lipids on crystal structure and chemical stability in solid lipid nanoparticles: Towards bioactive-based design of delivery systems.

PubMed

Salminen, Hanna; Gömmel, Christina; Leuenberger, Bruno H; Weiss, Jochen

2016-01-01

We investigated the influence of physicochemical properties of encapsulated functional lipids--vitamin A, β-carotene and ω-3 fish oil--on the structural arrangement of solid lipid nanoparticles (SLN). The relationship between the crystal structure and chemical stability of the incorporated bioactive lipids was evaluated with different emulsifier compositions of a saponin-rich, food-grade Quillaja extract alone or combined with high-melting or low-melting lecithins. The major factors influencing the structural arrangement and chemical stability of functional lipids in solid lipid dispersions were their solubility in the aqueous phase and their crystallization temperature in relation to that of the carrier lipid. The results showed that the stabilization of the α-subcell crystals in the lattice of the carrier lipid is a key parameter for forming stable solid lipid dispersions. This study contributes to a better understanding of SLN as a function of the bioactive lipid. Copyright © 2015 Elsevier Ltd. All rights reserved.

Introduction to fatty acids and lipids.

PubMed

Burdge, Graham C; Calder, Philip C

2015-01-01

The purpose of this article is to describe the structure, function and metabolism of fatty acids and lipids that are of particular importance in the context of parenteral nutrition. Lipids are a heterogeneous group of molecules that share the common property of hydrophobicity. Lipids range in structure from simple short hydrocarbon chains to more complex molecules, including triacylglycerols, phospholipids and sterols and their esters. Lipids within each class may differ structurally. Fatty acids are common components of complex lipids, and these differ according to chain length and the presence, number and position of double bonds in the hydrocarbon chain. Structural variation among complex lipids and among fatty acids gives rise to functional differences that result in different impacts upon metabolism and upon cell and tissue responses. Fatty acids and complex lipids exhibit a variety of structural variations that influence their metabolism and their functional effects. © 2015 S. Karger AG, Basel.

Separation, hydrolysis and fermentation of pyrolytic sugars to produce ethanol and lipids.

PubMed

Lian, Jieni; Chen, Shulin; Zhou, Shuai; Wang, Zhouhong; O'Fallon, James; Li, Chun-Zhu; Garcia-Perez, Manuel

2010-12-01

This paper describes a new scheme to convert anhydrosugars found in pyrolysis oils into ethanol and lipids. Pyrolytic sugars were separated from phenols by solvent extraction and were hydrolyzed into glucose using sulfuric acid as a catalyst. Toxicological studies showed that phenols and acids were the main species inhibiting growth of the yeast Saccharomyces cerevisiae. The sulfuric acids, and carboxylic acids from the bio-oils, were neutralized with Ba(OH)(2). The phase rich in sugar was further detoxified with activated carbon. The resulting aqueous phase rich in glucose was fermented with three different yeasts: S. cerevisiae to produce ethanol, and Cryptococcus curvatus and Rhodotorula glutinis to produce lipids. Yields as high as 0.473 g ethanol/g glucose and 0.167 g lipids/g sugar (0.266 g ethanol equivalent/g sugar), were obtained. These results confirm that pyrolytic sugar fermentation to produce ethanol is more efficient than for lipid production. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Human LDL Structural Diversity Studied by IR Spectroscopy

PubMed Central

Fernández-Higuero, José A.; Salvador, Ana M.; Martín, Cesar; Milicua, José Carlos G.; Arrondo, José L. R.

2014-01-01

Lipoproteins are responsible for cholesterol traffic in humans. Low density lipoprotein (LDL) delivers cholesterol from liver to peripheral tissues. A misleading delivery can lead to the formation of atherosclerotic plaques. LDL has a single protein, apoB-100, that binds to a specific receptor. It is known that the failure associated with a deficient protein-receptor binding leads to plaque formation. ApoB-100 is a large single lipid-associated polypeptide difficulting the study of its structure. IR spectroscopy is a technique suitable to follow the different conformational changes produced in apoB-100 because it is not affected by the size of the protein or the turbidity of the sample. We have analyzed LDL spectra of different individuals and shown that, even if there are not big structural changes, a different pattern in the intensity of the band located around 1617 cm−1 related with strands embedded in the lipid monolayer, can be associated with a different conformational rearrangement that could affect to a protein interacting region with the receptor. PMID:24642788

Role of Transbilayer Distribution of Lipid Molecules on the Structure and Protein-Lipid Interaction of an Amyloidogenic Protein on the Membrane Surface

NASA Astrophysics Data System (ADS)

Cheng, Kwan; Cheng, Sara

We used molecular dynamics simulations to examine the effects of transbilayer distribution of lipid molecules, particularly anionic lipids with negatively charged headgroups, on the structure and binding kinetics of an amyloidogenic protein on the membrane surface and subsequent protein-induced structural disruption of the membrane. Our systems consisted of a model beta-sheet rich dimeric protein absorbed on asymmetric bilayers with neutral and anionic lipids and symmetric bilayers with neutral lipids. We observed larger folding, domain aggregation, and tilt angle of the absorbed protein on the asymmetric bilayer surfaces. We also detected more focused bilayer thinning in the asymmetric bilayer due to weak lipid-protein interactions. Our results support the mechanism that the higher lipid packing in the protein-contacting lipid leaflet promotes stronger protein-protein but weaker protein-lipid interactions of an amyloidogenic protein on the membrane surface. We speculate that the observed surface-induced structural and protein-lipid interaction of our model amyloidogenic protein may play a role in the early membrane-associated amyloid cascade pathway that leads to membrane structural damage of neurons in Alzheimer's disease. NSF ACI-1531594.

Phase Transitions of Isotropic to Anisotropic Biocompatible Lipid-Based Drug Delivery Systems Overcoming Insoluble Benznidazole Loading.

PubMed

Streck, Letícia; Sarmento, Víctor H V; Machado, Paula R L; Farias, Kleber J S; Fernandes-Pedrosa, Matheus F; da Silva-Júnior, Arnóbio Antônio

2016-06-30

Previous studies reported low benznidazole (BNZ) loading in conventional emulsions due to the weak interaction of the drug with the most common oils used to produce foods or pharmaceuticals. In this study, we focused on how the type of surfactant, surfactant-to-oil ratio w/w (SOR) and oil-to-water ratio w/w (OWR) change the phase behavior of different lipid-based drug delivery systems (LBDDS) produced by emulsion phase inversion. The surfactant mixture composed of soy phosphatidylcholine and sodium oleate (1:7, w/w, hydrophilic lipophilic balance = 16) stabilized medium chain triglyceride in water. Ten formulations with the clear aspect or less turbid dispersions (five with the SOR ranging from 0.5 to 2.5 and five with the OWR from 0.06 to 0.4) were selected from the phase behavior diagram to assess structural features and drug-loading capacity. The rise in the SOR induced the formation of distinct lipid-based drug delivery systems (nanoemulsions and liquid crystal lamellar type) that were identified using rheological measurements and cross-polarized light microscopy images. Clear dispersions of small and narrow droplet-sized liquid-like nanoemulsions, Newtonian flow-type, were produced at SOR from 0.5 to 1.5 and OWR from 0.12 to 0.4, while clear liquid or gel-like liquid crystals were produced at SOR from 1.5 to 2.5. The BNZ loading was improved according to the composition and type of LBDDS produced, suggesting possible drug location among surfactant layers. The cell viability assays proved the biocompatibility for all of the prepared nanoemulsions at SOR less than 1.5 and liquid crystals at SOR less than 2.5, demonstrating their promising features for the oral or parenteral colloidal delivery systems containing benznidazole for Chagas disease treatment.

Phase Transitions of Isotropic to Anisotropic Biocompatible Lipid-Based Drug Delivery Systems Overcoming Insoluble Benznidazole Loading

PubMed Central

Streck, Letícia; Sarmento, Víctor H. V.; Machado, Paula R. L.; Farias, Kleber J. S.; Fernandes-Pedrosa, Matheus F.; da Silva-Júnior, Arnóbio Antônio

2016-01-01

Previous studies reported low benznidazole (BNZ) loading in conventional emulsions due to the weak interaction of the drug with the most common oils used to produce foods or pharmaceuticals. In this study, we focused on how the type of surfactant, surfactant-to-oil ratio w/w (SOR) and oil-to-water ratio w/w (OWR) change the phase behavior of different lipid-based drug delivery systems (LBDDS) produced by emulsion phase inversion. The surfactant mixture composed of soy phosphatidylcholine and sodium oleate (1:7, w/w, hydrophilic lipophilic balance = 16) stabilized medium chain triglyceride in water. Ten formulations with the clear aspect or less turbid dispersions (five with the SOR ranging from 0.5 to 2.5 and five with the OWR from 0.06 to 0.4) were selected from the phase behavior diagram to assess structural features and drug-loading capacity. The rise in the SOR induced the formation of distinct lipid-based drug delivery systems (nanoemulsions and liquid crystal lamellar type) that were identified using rheological measurements and cross-polarized light microscopy images. Clear dispersions of small and narrow droplet-sized liquid-like nanoemulsions, Newtonian flow-type, were produced at SOR from 0.5 to 1.5 and OWR from 0.12 to 0.4, while clear liquid or gel-like liquid crystals were produced at SOR from 1.5 to 2.5. The BNZ loading was improved according to the composition and type of LBDDS produced, suggesting possible drug location among surfactant layers. The cell viability assays proved the biocompatibility for all of the prepared nanoemulsions at SOR less than 1.5 and liquid crystals at SOR less than 2.5, demonstrating their promising features for the oral or parenteral colloidal delivery systems containing benznidazole for Chagas disease treatment. PMID:27376278

Physiological Effects of Free Fatty Acid Production in Genetically Engineered Synechococcus elongatus PCC 7942

PubMed Central

Ruffing, Anne M.; Jones, Howland D.T.

2012-01-01

The direct conversion of carbon dioxide into biofuels by photosynthetic microorganisms is a promising alternative energy solution. In this study, a model cyanobacterium, Synechococcus elongatus PCC 7942, is engineered to produce free fatty acids (FFA), potential biodiesel precursors, via gene knockout of the FFA-recycling acyl-ACP synthetase and expression of a thioesterase for release of the FFA. Similar to previous efforts, the engineered strains produce and excrete FFA, but the yields are too low for large-scale production. While other efforts have applied additional metabolic engineering strategies in an attempt to boost FFA production, we focus on characterizing the engineered strains to identify the physiological effects that limit cell growth and FFA synthesis. The strains engineered for FFA-production show reduced photosynthetic yields, chlorophyll-a degradation, and changes in the cellular localization of the light-harvesting pigments, phycocyanin and allophycocyanin. Possible causes of these physiological effects are also identified. The addition of exogenous linolenic acid, a polyunsaturated FFA, to cultures of S. elongatus 7942 yielded a physiological response similar to that observed in the FFA-producing strains with only one notable difference. In addition, the lipid constituents of the cell and thylakoid membranes in the FFA-producing strains show changes in both the relative amounts of lipid components and the degree of saturation of the fatty acid side chains. These changes in lipid composition may affect membrane integrity and structure, the binding and diffusion of phycobilisomes, and the activity of membrane-bound enzymes including those involved in photosynthesis. Thus, the toxicity of unsaturated FFA and changes in membrane composition may be responsible for the physiological effects observed in FFA-producing S. elongatus 7942. These issues must be addressed to enable the high yields of FFA synthesis necessary for large-scale biofuel production. PMID:22473793

Improved Tumor Targeting of Polymer-based Nanovesicles Using Polymer-Lipid Blends

PubMed Central

Cheng, Zhiliang; Elias, Drew R.; Kamat, Neha P.; Johnston, Eric D.; Poloukhtine, Andrei; Popik, Vladimir; Hammer, Daniel A.; Tsourkas, Andrew

2011-01-01

Block copolymer-based vesicles have recently garnered a great deal of interest as nanoplatforms for drug delivery and molecular imaging applications due to their unique structural properties. These nanovesicles have been shown to direct their cargo to disease sites either through enhanced permeability and retention or even more efficiently via active targeting. Here we show that the efficacy of nanovesicle targeting can be significantly improved when prepared from polymer-lipid blends compared with block copolymer alone. Polymer-lipid hybrid nanovesicles were produced from the aqueous co-assembly of the diblock copolymer, poly(ethylene oxide)-block-polybutadiene (PEO-PBD), and the phospholipid, hydrogenated soy phosphatidylcholine (HSPC). The PEG-based vesicles, 117 nm in diameter, were functionalized with either folic acid or anti-HER2/neu affibodies as targeting ligands to confer specificity for cancer cells. Our results revealed that nanovesicles prepared from polymer-lipid blends led to significant improvement in cell binding compared to nanovesicles prepared from block copolymer alone in both in vitro cell studies and murine tumor models. Therefore, it is envisioned that nanovesicles composed of polymer-lipid blends may constitute a preferred embodiment for targeted drug delivery and molecular imaging applications. PMID:21899335

Tunneling in green tea: understanding the antioxidant activity of catechol-containing compounds. A variational transition-state theory study.

PubMed

Tejero, Ismael; Gonzalez-García, Núria; Gonzalez-Lafont, Angels; Lluch, José M

2007-05-09

The catechol functionality present in the catechins is responsible for the protective effects exerted by green tea against a wide range of human diseases. High-level electronic structure calculations and canonical variational transition-state theory including multidimensional tunneling corrections have allowed us to understand the key factors of the antioxidant effectiveness of the catechol group. This catechol group forms two hydrogen bonds with the two oxygen atoms of the lipid peroxyl radical, leading to a very compact reactant complex. This fact produces an extremely narrow adiabatic potential-energy profile corresponding to the hydrogen abstraction by the peroxyl radical, which makes it possible for a huge tunneling contribution to take place. So, quantum-mechanical tunneling highly increases the corresponding rate constant value, in such a way that catechins become able to trap the lipid peroxyl radicals in a dominant competition with the very damaging free-radical chain-lipid peroxidation reaction.

Effect of saliva on physical food properties in fat texture perception.

PubMed

Kupirovič, Urška Pivk; Elmadfa, Ibrahim; Juillerat, Marcel-Alexandre; Raspor, Peter

2017-04-13

Sensory properties of food drive our food choices and it is generally accepted that lipids greatly contribute to the sensory properties of many foods and consequently to eating pleasure. Many studies have investigated the mechanisms of the fat perception. Unfortunately they used a variety of methods and products, thereby making generalization very difficult. The mechanism of fat perception in oral cavity is combined of several processes. Lipid composition and its properties strongly influence food structure. During consumption food is exposed to a range of in-mouth processing steps. Oral sensation of fat texture changes with time, from a first bite to chewing, while mixing with saliva, up to swallowing and even after swallowing. The present work reviews many aspects of fat texture perception from physical chemistry to physiology. Understanding the underlying mechanisms of in-mouth lipid processing would provide new concepts to produce low-fat food products with full-fat perception.

ON THE FREEZING AND IDENTIFICATION OF LIPID MONOLAYER 2-D ARRAYS FOR CRYOELECTRON MICROSCOPY

PubMed Central

Taylor, Dianne W.; Kelly, Deborah F.; Cheng, Anchi; Taylor, Kenneth A.

2008-01-01

Lipid monolayers provide a convenient vehicle for the crystallization of biological macromolecules for 3-D electron microscopy. Although numerous examples of 3-D images from 2-D protein arrays have been described from negatively stained specimens, only six structures have been done from frozen hydrated specimens. We describe here a method that makes high quality frozen-hydrated specimens of lipid monolayer arrays for cryoelectron microscopy. The method uses holey carbon films with patterned holes for monolayer recovery, blotting and plunge freezing to produce thin aqueous films which cover >90% of the available grid area. With this method, even specimens with relatively infrequent crystals can be screened using automated data collection techniques. Though developed for microscopic examination of 2-D arrays, the method may have wider application to the preparation of single particle specimens for 3-D image reconstruction. PMID:17561414

Fourier transform coupled tryptophan scanning mutagenesis identifies a bending point on the lipid-exposed δM3 transmembrane domain of the Torpedo californica nicotinic acetylcholine receptor

PubMed Central

Caballero-Rivera, Daniel; Cruz-Nieves, Omar A; Oyola-Cintrón, Jessica; Torres-Núñez, David A; Otero-Cruz, José D

2011-01-01

The nicotinic acetylcholine receptor (nAChR) is a member of a family of ligand-gated ion channels that mediate diverse physiological functions, including fast synaptic transmission along the peripheral and central nervous systems. Several studies have made significant advances toward determining the structure and dynamics of the lipid-exposed domains of the nAChR. However, a high-resolution atomic structure of the nAChR still remains elusive. In this study, we extended the Fourier transform coupled tryptophan scanning mutagenesis (FT-TrpScanM) approach to gain insight into the secondary structure of the δM3 transmembrane domain of the Torpedo californica nAChR, to monitor conformational changes experienced by this domain during channel gating, and to identify which lipid-exposed positions are linked to the regulation of ion channel kinetics. The perturbations produced by periodic tryptophan substitutions along the δM3 transmembrane domain were characterized by two-electrode voltage clamp and 125I-labeled α-bungarotoxin binding assays. The periodicity profiles and Fourier transform spectra of this domain revealed similar helical structures for the closed- and open-channel states. However, changes in the oscillation patterns observed between positions Val-299 and Val-304 during transition between the closed- and open-channel states can be explained by the structural effects caused by the presence of a bending point introduced by a Thr-Gly motif at positions 300–301. The changes in periodicity and localization of residues between the closed-and open-channel states could indicate a structural transition between helix types in this segment of the domain. Overall, the data further demonstrate a functional link between the lipid-exposed transmembrane domain and the nAChR gating machinery. PMID:21785268

Bioconversion of volatile fatty acids derived from waste activated sludge into lipids by Cryptococcus curvatus.

PubMed

Liu, Jia; Liu, Jia-Nan; Yuan, Ming; Shen, Zi-Heng; Peng, Kai-Ming; Lu, Li-Jun; Huang, Xiang-Feng

2016-07-01

Pure volatile fatty acid (VFA) solution derived from waste activated sludge (WAS) was used to produce microbial lipids as culture medium in this study, which aimed to realize the resource recovery of WAS and provide low-cost feedstock for biodiesel production simultaneously. Cryptococcus curvatus was selected among three oleaginous yeast to produce lipids with VFAs derived from WAS. In batch cultivation, lipid contents increased from 10.2% to 16.8% when carbon to nitrogen ratio increased from about 3.5 to 165 after removal of ammonia nitrogen by struvite precipitation. The lipid content further increased to 39.6% and the biomass increased from 1.56g/L to 4.53g/L after cultivation for five cycles using sequencing batch culture (SBC) strategy. The lipids produced from WAS-derived VFA solution contained nearly 50% of monounsaturated fatty acids, including palmitic acid, heptadecanoic acid, ginkgolic acid, stearic acid, oleic acid, and linoleic acid, which showed the adequacy of biodiesel production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Temperature and pressure tuneable swollen bicontinuous cubic phases approaching nature's length scales.

PubMed

Barriga, H M G; Tyler, A I I; McCarthy, N L C; Parsons, E S; Ces, O; Law, R V; Seddon, J M; Brooks, N J

2015-01-21

Bicontinuous cubic structures offer enormous potential in applications ranging from protein crystallisation to drug delivery systems and have been observed in cellular membrane structures. One of the current bottlenecks in understanding and exploiting these structures is that cubic scaffolds produced in vitro are considerably smaller in size than those observed in biological systems, differing by almost an order of magnitude in some cases. We have addressed this technological bottleneck and developed a methodology capable of manufacturing highly swollen bicontinuous cubic membranes with length scales approaching those seen in vivo. Crucially, these cubic systems do not require the presence of proteins. We have generated highly swollen Im3m symmetry bicontinuous cubic phases with lattice parameters of up to 480 Å, composed of ternary mixtures of monoolein, cholesterol and negatively charged lipid (DOPS or DOPG) and we have been able to tune their lattice parameters. The swollen cubic phases are highly sensitive to both temperature and pressure; these structural changes are likely to be controlled by a fine balance between lipid headgroup repulsions and lateral pressure in the hydrocarbon chain region.

Irregular bilayer structure in vesicles prepared from Halobacterium cutirubrum lipids

NASA Technical Reports Server (NTRS)

Lanyi, J. K.

1974-01-01

Fluorescent probes were used to study the structure of the cell envelope of Halobacterium cutirubrum, and, in particular, to explore the effect of the heterogeneity of the lipids in this organism on the structure of the bilayers. The fluorescence polarization of perylene was followed in vesicles of unfractionated lipids and polar lipids as a function of temperature in 3.4 M solutions of NaCl, NaNO3, and KSCN, and it was found that vesicles of unfractionated lipids were more perturbed by chaotropic agents than polar lipids. The dependence of the relaxation times of perylene on temperature was studied in cell envelopes and in vesicles prepared from polar lipids, unfractionated lipids, and mixtures of polar and neutral lipids.

Shallow boomerang-shaped influenza hemagglutinin G13A mutant structure promotes leaky membrane fusion.

PubMed

Lai, Alex L; Tamm, Lukas K

2010-11-26

Our previous studies showed that an angled boomerang-shaped structure of the influenza hemagglutinin (HA) fusion domain is critical for virus entry into host cells by membrane fusion. Because the acute angle of ∼105° of the wild-type fusion domain promotes efficient non-leaky membrane fusion, we asked whether different angles would still support fusion and thus facilitate virus entry. Here, we show that the G13A fusion domain mutant produces a new leaky fusion phenotype. The mutant fusion domain structure was solved by NMR spectroscopy in a lipid environment at fusion pH. The mutant adopted a boomerang structure similar to that of wild type but with a shallower kink angle of ∼150°. G13A perturbed the structure of model membranes to a lesser degree than wild type but to a greater degree than non-fusogenic fusion domain mutants. The strength of G13A binding to lipid bilayers was also intermediate between that of wild type and non-fusogenic mutants. These membrane interactions provide a clear link between structure and function of influenza fusion domains: an acute angle is required to promote clean non-leaky fusion suitable for virus entry presumably by interaction of the fusion domain with the transmembrane domain deep in the lipid bilayer. A shallower angle perturbs the bilayer of the target membrane so that it becomes leaky and unable to form a clean fusion pore. Mutants with no fixed boomerang angle interacted with bilayers weakly and did not promote any fusion or membrane perturbation.

Shallow Boomerang-shaped Influenza Hemagglutinin G13A Mutant Structure Promotes Leaky Membrane Fusion*

PubMed Central

Lai, Alex L.; Tamm, Lukas K.

2010-01-01

Our previous studies showed that an angled boomerang-shaped structure of the influenza hemagglutinin (HA) fusion domain is critical for virus entry into host cells by membrane fusion. Because the acute angle of ∼105° of the wild-type fusion domain promotes efficient non-leaky membrane fusion, we asked whether different angles would still support fusion and thus facilitate virus entry. Here, we show that the G13A fusion domain mutant produces a new leaky fusion phenotype. The mutant fusion domain structure was solved by NMR spectroscopy in a lipid environment at fusion pH. The mutant adopted a boomerang structure similar to that of wild type but with a shallower kink angle of ∼150°. G13A perturbed the structure of model membranes to a lesser degree than wild type but to a greater degree than non-fusogenic fusion domain mutants. The strength of G13A binding to lipid bilayers was also intermediate between that of wild type and non-fusogenic mutants. These membrane interactions provide a clear link between structure and function of influenza fusion domains: an acute angle is required to promote clean non-leaky fusion suitable for virus entry presumably by interaction of the fusion domain with the transmembrane domain deep in the lipid bilayer. A shallower angle perturbs the bilayer of the target membrane so that it becomes leaky and unable to form a clean fusion pore. Mutants with no fixed boomerang angle interacted with bilayers weakly and did not promote any fusion or membrane perturbation. PMID:20826788

Membrane proteins bind lipids selectively to modulate their structure and function.

PubMed

Laganowsky, Arthur; Reading, Eamonn; Allison, Timothy M; Ulmschneider, Martin B; Degiacomi, Matteo T; Baldwin, Andrew J; Robinson, Carol V

2014-06-05

Previous studies have established that the folding, structure and function of membrane proteins are influenced by their lipid environments and that lipids can bind to specific sites, for example, in potassium channels. Fundamental questions remain however regarding the extent of membrane protein selectivity towards lipids. Here we report a mass spectrometry approach designed to determine the selectivity of lipid binding to membrane protein complexes. We investigate the mechanosensitive channel of large conductance (MscL) from Mycobacterium tuberculosis and aquaporin Z (AqpZ) and the ammonia channel (AmtB) from Escherichia coli, using ion mobility mass spectrometry (IM-MS), which reports gas-phase collision cross-sections. We demonstrate that folded conformations of membrane protein complexes can exist in the gas phase. By resolving lipid-bound states, we then rank bound lipids on the basis of their ability to resist gas phase unfolding and thereby stabilize membrane protein structure. Lipids bind non-selectively and with high avidity to MscL, all imparting comparable stability; however, the highest-ranking lipid is phosphatidylinositol phosphate, in line with its proposed functional role in mechanosensation. AqpZ is also stabilized by many lipids, with cardiolipin imparting the most significant resistance to unfolding. Subsequently, through functional assays we show that cardiolipin modulates AqpZ function. Similar experiments identify AmtB as being highly selective for phosphatidylglycerol, prompting us to obtain an X-ray structure in this lipid membrane-like environment. The 2.3 Å resolution structure, when compared with others obtained without lipid bound, reveals distinct conformational changes that re-position AmtB residues to interact with the lipid bilayer. Our results demonstrate that resistance to unfolding correlates with specific lipid-binding events, enabling a distinction to be made between lipids that merely bind from those that modulate membrane protein structure and/or function. We anticipate that these findings will be important not only for defining the selectivity of membrane proteins towards lipids, but also for understanding the role of lipids in modulating protein function or drug binding.

Hypocholesterolemic effects of low calorie structured lipids on rats and rabbits fed on normal and atherogenic diet.

PubMed

Kanjilal, Sanjit; Kaki, Shiva Shanker; Rao, Bhamidipati V S K; Sugasini, Dhavamani; Rao, Yalagala Poornachandra; Prasad, Rachapudi B N; Lokesh, Belur R

2013-01-01

The hypocholesterolemic effects of two low calorie structured lipids (SL1 and SL2) containing essential fatty acids, prepared by lipase catalysed interesterification of ethyl behenate respectively with sunflower and soybean oils were studied in rats and rabbits. The feeding experiment conducted on rats as well as rabbits, fed on normal and atherogenic diet containing 10% of SL1 and SL2 (experimental) and sunflower oil (control) indicated no adverse effects on growth and food intake. However, the structured lipids beneficially lowered serum and liver lipids, particularly cholesterol, LDL cholesterol, triglycerides and also maintains the essential fatty acid status in serum and liver. The lipid deposition observed in the arteries of rabbits fed on atherogenic diets was significantly reduced when structured lipids were included in the diet. These observations coincided with reduced levels of serum cholesterol particularly LDL cholesterol observed in experimental groups. Therefore the structured lipids, designed to have low calorific value also beneficially lower serum lipids and lipid deposition in animals fed on atherogenic diets. Copyright © 2012 Elsevier Ltd. All rights reserved.

2011 Plant Lipids: Structure, Metabolism, & Function Gordon Research Conference

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christopher Benning

2011-02-04

This is the second Gordon Research Conference on 'Plant Lipids: Structure, Metabolism & Function'. It covers current topics in lipid structure, metabolism and function in eukaryotic photosynthetic organisms including seed plants, algae, mosses and ferns. Work in photosynthetic bacteria is considered as well as it serves the understanding of specific aspects of lipid metabolism in plants. Breakthroughs are discussed in research on plant lipids as diverse as glycerolipids, sphingolipids, lipids of the cell surface, isoprenoids, fatty acids and their derivatives. The program covers nine concepts at the forefront of research under which afore mentioned plant lipid classes are discussed. Themore » goal is to integrate areas such as lipid signaling, basic lipid metabolism, membrane function, lipid analysis, and lipid engineering to achieve a high level of stimulating interaction among diverse researchers with interests in plant lipids. One Emphasis is on the dynamics and regulation of lipid metabolism during plant cell development and in response to environmental factors.« less

Cyclen-based double-tailed lipids for DNA delivery: Synthesis and the effect of linking group structures.

PubMed

Zhang, Yi-Mei; Chang, De-Chun; Zhang, Ji; Liu, Yan-Hong; Yu, Xiao-Qi

2015-09-01

The gene transfection efficiency (TE) of cationic lipids is largely influenced by the lipid structure. Six novel 1, 4, 7, 10-tetraazacyclododecane (cyclen)-based cationic lipids L1-L6, which contain double oleyl as hydrophobic tails, were designed and synthesized. The difference between these lipids is their diverse backbone. Liposomes prepared by the lipids and DOPE showed good DNA affinity, and full DNA condensation could be achieved at N/P of 4 to form lipoplexes with proper size and zeta-potentials for gene transfection. Structure-activity relationship of these lipids as non-viral gene delivery vectors was investigated. It was found that minor backbone structural variations, including linking group and the structural symmetry would affect the TE. The diethylenetriamine derived lipid L4 containing amide linking bonds gave the best TE, which was several times higher than commercially available transfection reagent lipofectamine 2000. Besides, these lipids exhibited low cytotoxicity, suggesting their good biocompatibility. Results reveal that such type of cationic lipids might be promising non-viral gene vectors, and also afford us clues for the design of novel vectors with higher TE and biocompatibility. Copyright © 2015 Elsevier Ltd. All rights reserved.

Lipid A structural modifications in extreme conditions and identification of unique modifying enzymes to define the Toll-like receptor 4 structure-activity relationship.

PubMed

Scott, Alison J; Oyler, Benjamin L; Goodlett, David R; Ernst, Robert K

2017-11-01

Strategies utilizing Toll-like receptor 4 (TLR4) agonists for treatment of cancer, infectious diseases, and other targets report promising results. Potent TLR4 antagonists are also gaining attention as therapeutic leads. Though some principles for TLR4 modulation by lipid A have been described, a thorough understanding of the structure-activity relationship (SAR) is lacking. Only through a complete definition of lipid A-TLR4 SAR is it possible to predict TLR4 signaling effects of discrete lipid A structures, rendering them more pharmacologically relevant. A limited 'toolbox' of lipid A-modifying enzymes has been defined and is largely composed of enzymes from mesophile human and zoonotic pathogens. Expansion of this 'toolbox' will result from extending the search into lipid A biosynthesis and modification by bacteria living at the extremes. Here, we review the fundamentals of lipid A structure, advances in lipid A uses in TLR4 modulation, and the search for novel lipid A-modifying systems in extremophile bacteria. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2017 Elsevier B.V. All rights reserved.

The ovary structure, previtellogenic and vitellogenic stages in parthenogenetic species Dactylobiotus dispar (Murray, 1907) (Tardigrada: Eutardigrada).

PubMed

Poprawa, Izabela

2005-10-01

The reproductive system of Dactylobiotus dispar consists of the ovary and the oviduct that opens into the rectum. The sack-like ovary is filled with the developing oocytes, which are assisted by the trophocytes. In D. dispar, the mixed vitellogenesis takes place. One part of the yolk material is produced inside the oocyte (autosynthesis), the second part is absorbed by micropinocytosis while the third part is synthesized in the trophocytes and is transported to the oocytes through the cytoplasmatic bridges. Moreover, rRNA, lipids and mitochondria are transfered from the trophocytes to the oocytes. The histochemical researches show that the reserve material accumulated in the oocytes contains proteins, polysaccharides and lipids.

Lipid mediators and their metabolism in the nucleous: implications for Alzheimer's disease.

PubMed

Farooqui, Akhlaq A

2012-01-01

Lipid mediators are important endogenous regulators derived from enzymatic degradation of glycerophospholipids, sphingolipids, and cholesterol by phospholipases, sphingomyelinases, and cytochrome P450 hydroxylases, respectively. In neural cells, lipid mediators are associated with proliferation, differentiation, oxidative stress, inflammation, and apoptosis. A major group of lipid mediators, which originates from the enzymatic oxidation of arachidonic acid, is called eicosanoids (i.e., prostaglandins, leukotrienes, thromboxanes, and lipoxins). The corresponding lipid mediators of docosahexaenoic acid metabolism are named as docosanoids. They include resolvins, protectins (neuroprotectins), and maresins. Docosanoids produce antioxidant, anti-inflammatory, and antiapoptotic effects in brain tissue. Other glycerophospholipid-derived lipid mediators are platelet activating factor, lysophosphatidic acid, and endocannabinoids. Degradation of sphingolipids also results in the generation of sphingolipid-derived lipid mediators, such as ceramide, ceramide 1-phosphate, sphingosine, and sphingosine 1-phosphate. These mediators are involved in differentiation, growth, cell migration, and apoptosis. Similarly, cholesterol-derived lipid mediators, hydroxycholesterol, produce apoptosis. Abnormal metabolism of lipid mediators may be closely associated with pathogenesis of Alzheimer's disease.

Diacylglycerol-enriched structured lipids containing CLA and capric acid alter body fat mass and lipid metabolism in rats.

PubMed

Kim, Hye-Jin; Lee, Ki-Teak; Lee, Mi-Kyung; Jeon, Seon-Min; Choi, Myung-Sook

2006-01-01

The present study compared the effect of corn oil, diacylglycerol (DG) oil, and DG-enriched structured lipids (SL-DG) produced from corn oil, capric and conjugated linoleic acid on adiposity in rats fed an AIN-76 diet (5% fat) for 6 weeks. The plasma and hepatic lipids, adipose tissue weight, and enzyme activities related to fatty acid metabolism were determined. The weights of the epididymal white adipose tissue (WAT), perirenal WAT, and interscapular WAT were significantly lower in the SL-DG group than in the DG group. Reduction of fat mass in the SL-DG group was related to suppressing fatty acid synthase activities and enhancing beta-oxidation activity in perirenal WAT. The plasma leptin was lower in the SL-DG group than in the DG group, plus a lower plasma TG level was accompanied by an increase in adipocyte LPL activity. Meanwhile the SL-DG supplement lowered the plasma and hepatic cholesterol level. In addition, the hepatic HMG-CoA reductase and ACAT activities were significantly lower in the SL-DG group than in the other groups. The DG-enriched SL used in this study was effective in enhancing triglyceride metabolism in adipose tissue, especially as regards reducing the abdominal fat mass and cholesterol metabolism in the liver. Copyright 2006 S. Karger AG, Basel.

Fatty acids from membrane lipids become incorporated into lipid bodies during Myxococcus xanthus differentiation.

PubMed

Bhat, Swapna; Boynton, Tye O; Pham, Dan; Shimkets, Lawrence J

2014-01-01

Myxococcus xanthus responds to amino acid limitation by producing fruiting bodies containing dormant spores. During development, cells produce triacylglycerides in lipid bodies that become consumed during spore maturation. As the cells are starved to induce development, the production of triglycerides represents a counterintuitive metabolic switch. In this paper, lipid bodies were quantified in wild-type strain DK1622 and 33 developmental mutants at the cellular level by measuring the cross sectional area of the cell stained with the lipophilic dye Nile red. We provide five lines of evidence that triacylglycerides are derived from membrane phospholipids as cells shorten in length and then differentiate into myxospores. First, in wild type cells, lipid bodies appear early in development and their size increases concurrent with an 87% decline in membrane surface area. Second, developmental mutants blocked at different stages of shortening and differentiation accumulated lipid bodies proportionate with their cell length with a Pearson's correlation coefficient of 0.76. Third, peripheral rods, developing cells that do not produce lipid bodies, fail to shorten. Fourth, genes for fatty acid synthesis are down-regulated while genes for fatty acid degradation are up regulated. Finally, direct movement of fatty acids from membrane lipids in growing cells to lipid bodies in developing cells was observed by pulse labeling cells with palmitate. Recycling of lipids released by Programmed Cell Death appears not to be necessary for lipid body production as a fadL mutant was defective in fatty acid uptake but proficient in lipid body production. The lipid body regulon involves many developmental genes that are not specifically involved in fatty acid synthesis or degradation. MazF RNA interferase and its target, enhancer-binding protein Nla6, appear to negatively regulate cell shortening and TAG accumulation whereas most cell-cell signals activate these processes.

Determination of lipid bilayer affinities and solvation characteristics by electrokinetic chromatography using polymer-bound lipid bilayer nanodiscs.

PubMed

Penny, William M; Palmer, Christopher P

2018-03-01

Styrene-maleic acid polymer-bound lipid bilayer nanodiscs have been investigated and characterized by electrokinetic chromatography. Linear solvation energy relationship analysis was employed to characterize the changes in solvation environment of nanodiscs of varied belt to lipid ratio, belt polymer chemistry and molecular weight, and lipid composition. Increases in the lipid to belt polymer ratio resulted in smaller, more cohesive nanodiscs with greater electrophoretic mobility. Nanodisc structures with belt polymers of different chemistry and molecular weight were compared and showed only minor changes in solvent characteristics and selectivity consistent with changes in structure of the lipid bilayer. Seven phospholipid and sphingomyelin nanodiscs of different lipid composition were characterized. Changes in lipid head group structure had a significant effect on bilayer-solute interactions. In most cases, changes in alkyl tail structure had no discernible effect on solvation environment aside from those explained by changes in the gel-liquid transition temperature. Comparison to vesicles of similar lipid composition show only minor differences in solvation environment, likely due to differences in lipid composition and bilayer curvature. Together these results provide evidence that the dominant solute-nanodisc interactions are with the lipid bilayer and that head group chemistry has a greater impact on bilayer-solute interactions than alkyl tail or belt polymer structure. Nanodisc electrokinetic chromatography is demonstrated to allow characterization of solute interactions with lipid bilayers of varied composition. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kdo2-lipid A: structural diversity and impact on immunopharmacology

PubMed Central

Wang, Xiaoyuan; Quinn, Peter J; Yan, Aixin

2015-01-01

3-deoxy-d-manno-octulosonic acid-lipid A (Kdo2-lipid A) is the essential component of lipopolysaccharide in most Gram-negative bacteria and the minimal structural component to sustain bacterial viability. It serves as the active component of lipopolysaccharide to stimulate potent host immune responses through the complex of Toll-like-receptor 4 (TLR4) and myeloid differentiation protein 2. The entire biosynthetic pathway of Escherichia coli Kdo2-lipid A has been elucidated and the nine enzymes of the pathway are shared by most Gram-negative bacteria, indicating conserved Kdo2-lipid A structure across different species. Yet many bacteria can modify the structure of their Kdo2-lipid A which serves as a strategy to modulate bacterial virulence and adapt to different growth environments as well as to avoid recognition by the mammalian innate immune systems. Key enzymes and receptors involved in Kdo2-lipid A biosynthesis, structural modification and its interaction with the TLR4 pathway represent a clear opportunity for immunopharmacological exploitation. These include the development of novel antibiotics targeting key biosynthetic enzymes and utilization of structurally modified Kdo2-lipid A or correspondingly engineered live bacteria as vaccines and adjuvants. Kdo2-lipid A/TLR4 antagonists can also be applied in anti-inflammatory interventions. This review summarizes recent knowledge on both the fundamental processes of Kdo2-lipid A biosynthesis, structural modification and immune stimulation, and applied research on pharmacological exploitations of these processes for therapeutic development. PMID:24838025

2013 plant lipids Gordon Research conference and Gordon Research Seminar (January 27 - February 1, 2013 - Hotel Galvez, Galveston, TX)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welti, Ruth

2012-11-01

Presenters will discuss the latest advances in plant and algal lipid metabolism, oil synthesis, lipid signaling, lipid visualization, lipid biotechnology and its applications, the physiological and developmental roles of lipids, and plant lipids in health. Sessions include: Producing Nutritional Lipids; Metabolic biochemistry in the next decade; Triacylglycerols: Metabolism, function, and as a target for engineering; Lipids in Protection, Reproduction, and Development; Genetic and Lipidomic Approaches to Understanding Lipid Metabolism and Signaling; Lipid Signaling in Stress Responses; New Insights on the Path to Triacylglycerols; Membrane Lipid Signaling; Lipid Visualization; Development of Biofuels and Industrial Lipids.

Characterization of Inulin Hydrolyzing Enzyme(s) in Oleaginous Yeast Trichosporon cutaneum in Consolidated Bioprocessing of Microbial Lipid Fermentation.

PubMed

Wang, Juan; Zhang, Huizhan; Bao, Jie

2015-11-01

Oleaginous yeast Trichosporon cutaneum CGMCC 2.1374 was found to utilize inulin directly for microbial lipid fermentation without a hydrolysis step. The potential inulinase-like enzyme(s) in T. cutaneum CGMCC 2.1374 were characterized and compared with other inulinase enzymes produced by varied yeast strains. The consolidated bioprocessing (CBP) for lipid accumulated using inulin was optimized with 4.79 g/L of lipid produced from 50 g/L inulin with the lipid content of 33.6% in dry cells. The molecular weight of the enzyme was measured which was close to invertase in Saccharomyces cerevisiae. The study provided information for inulin hydrolyzing enzyme(s) in oleaginous yeasts, as well as a preliminary CBP process for lipid production from inulin feedstock.

Fat emulsions based on structured lipids (1,3-specific triglycerides): an investigation of the in vivo fate.

PubMed

Hedeman, H; Brøndsted, H; Müllertz, A; Frokjaer, S

1996-05-01

Structured lipids (1,3-specific triglycerides) are new chemical entities made by enzymatic transesterification of the fatty acids in the 1,3 positions of the triglyceride. The purpose of this study is to characterize structured lipids with either short chain fatty acids or medium chain fatty acids in the 1,3 positions with regard to their hydrophobicity, and investigate the in vivo fate in order to evaluate the potential of structured lipids as core material in fat emulsions used as parenteral drug delivery system. The lipids were characterized by employing reversed phase high performance liquid chromatography. The biodistribution of radioactively labeled emulsions was studied in rats. By employing high performance liquid chromatography a rank order of the hydrophobicities of the lipids could be given, with the triglycerides containing long chain fatty acids being the most hydrophobic and the structured lipid with short chain fatty acids in the 1,3 positions the least. When formulated as fat emulsions, the emulsion based on structured lipids with short fatty acids in the 1,3 positions was removed slower from the general blood circulation compared to emulsions based on lipids with long chain fatty acids in the 1,3 positions. The type of core material influences the in vivo circulation time of fat emulsions.

Microalgal lipids biochemistry and biotechnological perspectives.

PubMed

Bellou, Stamatia; Baeshen, Mohammed N; Elazzazy, Ahmed M; Aggeli, Dimitra; Sayegh, Fotoon; Aggelis, George

2014-12-01

In the last few years, there has been an intense interest in using microalgal lipids in food, chemical and pharmaceutical industries and cosmetology, while a noteworthy research has been performed focusing on all aspects of microalgal lipid production. This includes basic research on the pathways of solar energy conversion and on lipid biosynthesis and catabolism, and applied research dealing with the various biological and technical bottlenecks of the lipid production process. In here, we review the current knowledge in microalgal lipids with respect to their metabolism and various biotechnological applications, and we discuss potential future perspectives. The committing step in fatty acid biosynthesis is the carboxylation of acetyl-CoA to form malonyl-CoA that is then introduced in the fatty acid synthesis cycle leading to the formation of palmitic and stearic acids. Oleic acid may also be synthesized after stearic acid desaturation while further conversions of the fatty acids (i.e. desaturations, elongations) occur after their esterification with structural lipids of both plastids and the endoplasmic reticulum. The aliphatic chains are also used as building blocks for structuring storage acylglycerols via the Kennedy pathway. Current research, aiming to enhance lipogenesis in the microalgal cell, is focusing on over-expressing key-enzymes involved in the earlier steps of the pathway of fatty acid synthesis. A complementary plan would be the repression of lipid catabolism by down-regulating acylglycerol hydrolysis and/or β-oxidation. The tendency of oleaginous microalgae to synthesize, apart from lipids, significant amounts of other energy-rich compounds such as sugars, in processes competitive to lipogenesis, deserves attention since the lipid yield may be considerably increased by blocking competitive metabolic pathways. The majority of microalgal production occurs in outdoor cultivation and for this reason biotechnological applications face some difficulties. Therefore, algal production systems need to be improved and harvesting systems need to be more effective in order for their industrial applications to become more competitive and economically viable. Besides, a reduction of the production cost of microalgal lipids can be achieved by combining lipid production with other commercial applications. The combined production of bioactive products and lipids, when possible, can support the commercial viability of both processes. Hydrophobic compounds can be extracted simultaneously with lipids and then purified, while hydrophilic compounds such as proteins and sugars may be extracted from the defatted biomass. The microalgae also have applications in environmental biotechnology since they can be used for bioremediation of wastewater and to monitor environmental toxicants. Algal biomass produced during wastewater treatment may be further valorized in the biofuel manufacture. It is anticipated that the high microalgal lipid potential will force research towards finding effective ways to manipulate biochemical pathways involved in lipid biosynthesis and towards cost effective algal cultivation and harvesting systems, as well. Copyright © 2014 Elsevier Inc. All rights reserved.

A Review on The Bioconversion of Lignin to Microbial Lipid with Oleaginous Rhodococcus opacus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahan, Kristina M.; Le, Rosemary K.; Yuan, Joshua

Rhodococcus opacus produces intracellular lipids from the biodegradation of lignocellulosic biomass. These lipids can be used to produce biofuels that could potentially replace petroleum-derived chemicals. Some current studies are focusing on deconstructing lignin through efficient and cost-effective pretreatment methods and improving microbial lipid titers. Furthermore, R. opacus can reach high levels of oleaginicity (>80%) when grown on glucose and other aromatic model compounds but intracellular lipid production is much lower on complex recalcitrant lignin substrates. Our review will discuss recent advances in studying R. opacus lignin degradation by exploring different pretreatment methods, increasing lignin solubility, enriching for low molecular weightmore » lignin compounds and laccase supplementation.« less

A Review on The Bioconversion of Lignin to Microbial Lipid with Oleaginous Rhodococcus opacus

DOE PAGES

Mahan, Kristina M.; Le, Rosemary K.; Yuan, Joshua; ...

2017-06-29

Rhodococcus opacus produces intracellular lipids from the biodegradation of lignocellulosic biomass. These lipids can be used to produce biofuels that could potentially replace petroleum-derived chemicals. Some current studies are focusing on deconstructing lignin through efficient and cost-effective pretreatment methods and improving microbial lipid titers. Furthermore, R. opacus can reach high levels of oleaginicity (>80%) when grown on glucose and other aromatic model compounds but intracellular lipid production is much lower on complex recalcitrant lignin substrates. Our review will discuss recent advances in studying R. opacus lignin degradation by exploring different pretreatment methods, increasing lignin solubility, enriching for low molecular weightmore » lignin compounds and laccase supplementation.« less

Chemical Changes in Lipids Produced by Thermal Processing.

ERIC Educational Resources Information Center

Nawar, Wassef W.

1984-01-01

Describes heat effects on lipids, indicating that the chemical and physical changes that occur depend on the lipid's composition and conditions of treatment. Thermolytic and oxidation reactions, thermal/oxidative interaction of lipids with other food components and the chemistry of frying are considered. (JN)

Examination of oral absorption and lymphatic transport of halofantrine in a triple-cannulated canine model after administration in self-microemulsifying drug delivery systems (SMEDDS) containing structured triglycerides.

PubMed

Holm, René; Porter, Christopher J H; Edwards, Glenn A; Müllertz, Anette; Kristensen, Henning G; Charman, William N

2003-09-01

The potential for lipidic self-microemulsifying drug delivery systems (SMEDDS) containing triglycerides with a defined structure, where the different fatty acids on the glycerol backbone exhibit different metabolic fate, to improve the lymphatic transport and the portal absorption of a poorly water-soluble drug, halofantrine, were investigated in fasted lymph cannulated canines. Two different structured triglycerides were incorporated into the SMEDDS; 1,3-dioctanoyl-2-linoleyl-sn-glycerol (C8:0-C18:2-C8:0) (MLM) and 1,3-dilinoyl-2-octanoyl-sn-glycerol (C18:2-C8:0-C18:2) (LML). A previously optimised SMEDDS formulation for halofantrine, comprising of triglyceride, Cremophor EL, Maisine 35-1 and ethanol was selected for bioavailability assessment. The extent of lymphatic transport via the thoracic duct was 17.9% of the dose for the animals dosed with the MLM SMEDDS and 27.4% for LML. Also the plasma availability was affected by the triglyceride incorporated into the multi-component delivery system and availabilities of 56.9% (MLM) and 37.2% (LML) were found. These data indicate that the pharmaceutical scientist can use the structure of the lipid to affect the relative contribution of the two absorption pathways. The MLM formulation produced a total bioavailability of 74.9%, which is higher than the total absorption previously observed after post-prandial administration. This could indicate the utility of disperse lipid-base formulations based on structured triglycerides for the oral delivery of halofantrine, and potentially other lipophilic drugs.

How Do the Size, Charge and Shape of Nanoparticles Affect Amyloid β Aggregation on Brain Lipid Bilayer?

NASA Astrophysics Data System (ADS)

Kim, Yuna; Park, Ji-Hyun; Lee, Hyojin; Nam, Jwa-Min

2016-01-01

Here, we studied the effect of the size, shape, and surface charge of Au nanoparticles (AuNPs) on amyloid beta (Aβ) aggregation on a total brain lipid-based supported lipid bilayer (brain SLB), a fluid platform that facilitates Aβ-AuNP aggregation process. We found that larger AuNPs induce large and amorphous aggregates on the brain SLB, whereas smaller AuNPs induce protofibrillar Aβ structures. Positively charged AuNPs were more strongly attracted to Aβ than negatively charged AuNPs, and the stronger interactions between AuNPs and Aβ resulted in fewer β-sheets and more random coil structures. We also compared spherical AuNPs, gold nanorods (AuNRs), and gold nanocubes (AuNCs) to study the effect of nanoparticle shape on Aβ aggregation on the brain SLB. Aβ was preferentially bound to the long axis of AuNRs and fewer fibrils were formed whereas all the facets of AuNCs interacted with Aβ to produce the fibril networks. Finally, it was revealed that different nanostructures induce different cytotoxicity on neuroblastoma cells, and, overall, smaller Aβ aggregates induce higher cytotoxicity. The results offer insight into the roles of NPs and brain SLB in Aβ aggregation on the cell membrane and can facilitate the understanding of Aβ-nanostructure co-aggregation mechanism and tuning Aβ aggregate structures.

Tubular growth and bead formation in the lyotropic lamellar phase of a lipid.

PubMed

Bhatia, Tripta; Hatwalne, Yashodhan; Madhusudana, N V

2015-07-28

We use fluorescence confocal polarised microscopy (FCPM) to study tubular growth upon hydration of dry DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) in water and water-glycerol mixtures. We have developed a model to relate the FCPM intensity profiles to the multilamellar structures of the tubules. Insertion of an additional patch inside a tubule produces a beaded structure, while a straight configuration is retained if the growth is on the outside. We use a simple model to suggest that reduction in overall curvature energy drives bead formation.

Molecular Characteristics and Biological Functions of Surface-Active and Surfactant Proteins.

PubMed

Sunde, Margaret; Pham, Chi L L; Kwan, Ann H

2017-06-20

Many critical biological processes take place at hydrophobic:hydrophilic interfaces, and a wide range of organisms produce surface-active proteins and peptides that reduce surface and interfacial tension and mediate growth and development at these boundaries. Microorganisms produce both small lipid-associated peptides and amphipathic proteins that allow growth across water:air boundaries, attachment to surfaces, predation, and improved bioavailability of hydrophobic substrates. Higher-order organisms produce surface-active proteins with a wide variety of functions, including the provision of protective foam environments for vulnerable reproductive stages, evaporative cooling, and gas exchange across airway membranes. In general, the biological functions supported by these diverse polypeptides require them to have an amphipathic nature, and this is achieved by a diverse range of molecular structures, with some proteins undergoing significant conformational change or intermolecular association to generate the structures that are surface active.

Structural interactions between lipids, water and S1-S4 voltage-sensing domains.

PubMed

Krepkiy, Dmitriy; Gawrisch, Klaus; Swartz, Kenton J

2012-11-02

Membrane proteins serve crucial signaling and transport functions, yet relatively little is known about their structures in membrane environments or how lipids interact with these proteins. For voltage-activated ion channels, X-ray structures suggest that the mobile voltage-sensing S4 helix would be exposed to the membrane, and functional studies reveal that lipid modification can profoundly alter channel activity. Here, we use solid-state NMR to investigate structural interactions of lipids and water with S1-S4 voltage-sensing domains and to explore whether lipids influence the structure of the protein. Our results demonstrate that S1-S4 domains exhibit extensive interactions with lipids and that these domains are heavily hydrated when embedded in a membrane. We also find evidence for preferential interactions of anionic lipids with S1-S4 domains and that these interactions have lifetimes on the timescale of ≤ 10(-3)s. Arg residues within S1-S4 domains are well hydrated and are positioned in close proximity to lipids, exhibiting local interactions with both lipid headgroups and acyl chains. Comparative studies with a positively charged lipid lacking a phosphodiester group reveal that this lipid modification has only modest effects on the structure and hydration of S1-S4 domains. Taken together, our results demonstrate that Arg residues in S1-S4 voltage-sensing domains reside in close proximity to the hydrophobic interior of the membrane yet are well hydrated, a requirement for carrying charge and driving protein motions in response to changes in membrane voltage. Published by Elsevier Ltd.

Structural interactions between lipids, water and S1-S4 voltage-sensing domains

PubMed Central

Krepkiy, Dmitriy; Gawrisch, Klaus; Swartz, Kenton J.

2012-01-01

Membrane proteins serve crucial signaling and transport functions, yet relatively little is known about their structures in membrane environments or how lipids interact with these proteins. For voltage-activated ion channels, X-ray structures suggest that the mobile voltage-sensing S4 helix would be exposed to the membrane, and functional studies reveal that lipid modification can profoundly alter channel activity. Here we use solid-state NMR to investigate structural interactions of lipids and water with S1-S4 voltage-sensing domains, and to explore whether lipids influence the structure of the protein. Our results demonstrate that S1-S4 domains exhibit extensive interactions with lipids, and that these domains are heavily hydrated when embedded in a membrane. We also find evidence for preferential interactions of anionic lipids with S1-S4 domains, and that these interactions have lifetimes on the timescale of 10−3s. Arg residues within S1-S4 domains are well-hydrated and are positioned in close proximity to lipids, exhibiting local interactions with both lipid head groups and acyl chains. Comparative studies with a positively charged lipid lacking a phosphodiester group reveal that this lipid modification has only modest effects on the structure and hydration of S1-S4 domains. Taken together, our results demonstrate that Arg residues in S1-S4 voltage-sensing domains reside in close proximity to the hydrophobic interior of the membrane, yet are well-hydrated, a requirement for carrying charge and driving protein motions in response to changes in membrane voltage. PMID:22858867

Lipid bilayers: thermodynamics, structure, fluctuations, and interactions.

PubMed

Tristram-Nagle, Stephanie; Nagle, John F

2004-01-01

This article, adapted from our acceptance speech of the Avanti Award in Lipids at the 47th Biophysical Society meeting in San Antonio, 2003, summarizes over 30 years of research in the area of lipid bilayers. Beginning with a theoretical model of the phase transition (J.F.N.), we have proceeded experimentally using dilatometry and density centrifugation to study volume, differential scanning calorimetry to study heat capacity, and X-ray scattering techniques to study structure of lipid bilayers as a function of temperature. Electron density profiles of the gel and ripple phases have been obtained as well as profiles from several fluid phase lipids, which lead to many structural results that compliment molecular dynamics simulations from other groups. Using the theory of liquid crystallography plus oriented lipid samples, we are the first group to obtain both material parameters (KC and B) associated with the fluctuations in fluid phase lipids. This allows us to use fully hydrated lipid samples, as in vivo, to obtain the structure.

Lipid bilayers: thermodynamics, structure, fluctuations, and interactions

PubMed Central

Tristram-Nagle, Stephanie; Nagle, John F.

2009-01-01

This article, adapted from our acceptance speech of the Avanti Award in Lipids at the 47th Biophysical Society meeting in San Antonio, 2003, summarizes over 30 years of research in the area of lipid bilayers. Beginning with a theoretical model of the phase transition (J.F.N.), we have proceeded experimentally using dilatometry and density centrifugation to study volume, differential scanning calorimetry to study heat capacity, and X-ray scattering techniques to study structure of lipid bilayers as a function of temperature. Electron density profiles of the gel and ripple phases have been obtained as well as profiles from several fluid phase lipids, which lead to many structural results that compliment molecular dynamics simulations from other groups. Using the theory of liquid crystallography plus oriented lipid samples, we are the first group to obtain both material parameters (KC and B) associated with the fluctuations in fluid phase lipids. This allows us to use fully hydrated lipid samples, as in vivo, to obtain the structure. PMID:14706737

Glycerolipid Characterization and Nutrient Deprivation-Associated Changes in the Green Picoalga Ostreococcus tauri1

PubMed Central

Degraeve-Guilbault, Charlotte; Bréhélin, Claire; Haslam, Richard; Jouhet, Juliette

2017-01-01

The picoalga Ostreococcus tauri is a minimal photosynthetic eukaryote that has been used as a model system. O. tauri is known to efficiently produce docosahexaenoic acid (DHA). We provide a comprehensive study of the glycerolipidome of O. tauri and validate this species as model for related picoeukaryotes. O. tauri lipids displayed unique features that combined traits from the green and the chromalveolate lineages. The betaine lipid diacylglyceryl-hydroxymethyl-trimethyl-β-alanine and phosphatidyldimethylpropanethiol, both hallmarks of chromalveolates, were identified as presumed extraplastidial lipids. DHA was confined to these lipids, while plastidial lipids of prokaryotic type were characterized by the overwhelming presence of ω-3 C18 polyunsaturated fatty acids (FAs), 18:5 being restricted to galactolipids. C16:4, an FA typical of green microalgae galactolipids, also was a major component of O. tauri extraplastidial lipids, while the 16:4-coenzyme A (CoA) species was not detected. Triacylglycerols (TAGs) displayed the complete panel of FAs, and many species exhibited combinations of FAs diagnostic for plastidial and extraplastidial lipids. Importantly, under nutrient deprivation, 16:4 and ω-3 C18 polyunsaturated FAs accumulated into de novo synthesized TAGs while DHA-TAG species remained rather stable, indicating an increased contribution of FAs of plastidial origin to TAG synthesis. Nutrient deprivation further severely down-regulated the conversion of 18:3 to 18:4, resulting in obvious inversion of the 18:3/18:4 ratio in plastidial lipids, TAGs, as well as acyl-CoAs. The fine-tuned and dynamic regulation of the 18:3/18:4 ratio suggested an important physiological role of these FAs in photosynthetic membranes. Acyl position in structural and storage lipids together with acyl-CoA analysis further help to determine mechanisms possibly involved in glycerolipid synthesis. PMID:28235892

Chemical composition and surfactant characteristics of marine foams investigated by means of UV-vis, FTIR and FTNIR spectroscopy.

PubMed

Mecozzi, Mauro; Pietroletti, Marco

2016-11-01

In this study, we collected the ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) and Fourier transform near-infrared (FTNIR) spectra of marine foams from different sites and foams produced by marine living organisms (i.e. algae and molluscs) to retrieve information about their molecular and structural composition. UV-vis spectra gave information concerning the lipid and pigment contents of foams. FTIR spectroscopy gave a more detailed qualitative information regarding carbohydrates, lipids and proteins in addition with information about the mineral contents of foams. FTNIR spectra confirmed the presence of carbohydrates, lipids and proteins in foams. Then, due to the higher content of structural information of FTIR spectroscopy with respect to FTNIR and UV-vis, we join the FTIR spectra of marine foams to those of humic substance from marine sediments and to the spectra of foams obtained by living organisms. We submitted this resulting FTIR spectral dataset to statistical multivariate methods to investigate specific aspects of foams such as structural similarity among foams and in addition, contributions from the organic matter of living organisms. Cluster analysis (CA) evidenced several cases (i.e. clusters) of marine foams having high structural similarity with foams from vegetal and animal samples and with humic substance extracted from sediments. These results suggested that all the living organisms of the marine environment can give contributions to the chemical composition of foams. Moreover, as CA also evidenced cases of structural differences within foam samples, we applied two-dimensional correlation analysis (2DCORR) to the FTIR spectra of marine foams to investigate the molecular characteristics which caused these structural differences. Asynchronous spectra of two-dimensional correlation analysis showed that the structural heterogeneity among foam samples depended reasonably on the presence and on the qualitative difference of electrostatic (hydrogen bonds) and nonpolar (van der Waals and π-π) interactions involving carbohydrate proteins and lipids present. The presence and relevance of these interactions agree with the supramolecular and surfactant characteristics of marine organic matter described in the scientific literature.

Modeling and optimization of lipid accumulation by Yarrowia lipolytica from glucose under nitrogen depletion conditions.

PubMed

Robles-Rodríguez, Carlos E; Muñoz-Tamayo, Rafael; Bideaux, Carine; Gorret, Nathalie; Guillouet, Stéphane E; Molina-Jouve, Carole; Roux, Gilles; Aceves-Lara, César A

2018-05-01

Oleaginous yeasts have been seen as a feasible alternative to produce the precursors of biodiesel due to their capacity to accumulate lipids as triacylglycerol having profiles with high content of unsaturated fatty acids. The yeast Yarrowia lipolytica is a promising microorganism that can produce lipids under nitrogen depletion conditions and excess of the carbon source. However, under these conditions, this yeast also produces citric acid (overflow metabolism) decreasing lipid productivity. This work presents two mathematical models for lipid production by Y. lipolytica from glucose. The first model is based on Monod and inhibition kinetics, and the second one is based on the Droop quota model approach, which is extended to yeast. The two models showed good agreements with the experimental data used for calibration and validation. The quota based model presented a better description of the dynamics of nitrogen and glucose dynamics leading to a good management of N/C ratio which makes this model interesting for control purposes. Then, quota model was used to evaluate, by means of simulation, a scenario for optimizing lipid productivity and lipid content. For that, a control strategy was designed by approximating the flow rates of glucose and nitrogen with piecewise linear functions. Simulation results achieved productivity of 0.95 g L -1  hr -1 and lipid content fraction of 0.23 g g -1 , which indicates that this strategy is a promising alternative for the optimization of lipid production. © 2017 Wiley Periodicals, Inc.

Dissecting metabolic behavior of lipid over-producing strain of Mucor circinelloides through genome-scale metabolic network and multi-level data integration.

PubMed

Vongsangnak, Wanwipa; Kingkaw, Amornthep; Yang, Junhuan; Song, Yuanda; Laoteng, Kobkul

2018-09-05

Lipid accumulation is an important cellular process of oleaginous microorganisms. To dissect metabolic behavior of oleaginous Zygomycetes, the lipid over-producing strain, Mucor circinelloides WJ11, was subjected for omics-scale analysis. The genome annotation was improved and used for construction of genome-scale metabolic network of WJ11 strain. Then, the quality of the metabolic network was enhanced by incorporating gene and protein expression data. In addition to the known oleaginous genes, our results showed a number of newly identified unique genes of WJ11 strain, which involved in central carbon metabolism, lipid, amino acid and nitrogen metabolisms. The systematic compilations indicated the additional metabolic routes with the involvement in supplying precursors (acetyl-CoA, NADPH and fatty acyl substrate) for fatty acid and lipid biosynthesis. Interestingly, amino acid metabolism played a substantial role in responsive mechanism of the fungal cells to nutrient imbalance circumstance through lipogenesis as the finding of reporter metabolites (l-methionine, l-glutamate, l-aspartate, l-asparagine and l-glutamine) at lipid-accumulating stage. The cooperative function of certain lipid-degrading enzymes at the particular growth stage was elucidated by integrating the metabolic networks with gene expression data. The unique feature of carotenoid biosynthetic route in WJ11 strain was also identified by protein domain analysis. Taken together, there were cross-functional metabolisms in regulating lipid biosynthesis and retaining high level of cellular lipids in the representative of lipid over-producing strains. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterisation of the Native Lipid Moiety of Echinococcus granulosus Antigen B

PubMed Central

Obal, Gonzalo; Ramos, Ana Lía; Silva, Valeria; Lima, Analía; Batthyany, Carlos; Bessio, María Inés; Ferreira, Fernando; Salinas, Gustavo; Ferreira, Ana María

2012-01-01

Antigen B (EgAgB) is the most abundant and immunogenic antigen produced by the larval stage (metacestode) of Echinococcus granulosus. It is a lipoprotein, the structure and function of which have not been completely elucidated. EgAgB apolipoprotein components have been well characterised; they share homology with a group of hydrophobic ligand binding proteins (HLBPs) present exclusively in cestode organisms, and consist of different isoforms of 8-kDa proteins encoded by a polymorphic multigene family comprising five subfamilies (EgAgB1 to EgAgB5). In vitro studies have shown that EgAgB apolipoproteins are capable of binding fatty acids. However, the identity of the native lipid components of EgAgB remains unknown. The present work was aimed at characterising the lipid ligands bound to EgAgB in vivo. EgAgB was purified to homogeneity from hydatid cyst fluid and its lipid fraction was extracted using chloroform∶methanol mixtures. This fraction constituted approximately 40–50% of EgAgB total mass. High-performance thin layer chromatography revealed that the native lipid moiety of EgAgB consists of a variety of neutral (mainly triacylglycerides, sterols and sterol esters) and polar (mainly phosphatidylcholine) lipids. Gas-liquid chromatography analysis showed that 16∶0, 18∶0 and 18∶1(n-9) are the most abundant fatty acids in EgAgB. Furthermore, size exclusion chromatography coupled to light scattering demonstrated that EgAgB comprises a population of particles heterogeneous in size, with an average molecular mass of 229 kDa. Our results provide the first direct evidence of the nature of the hydrophobic ligands bound to EgAgB in vivo and indicate that the structure and composition of EgAgB lipoprotein particles are more complex than previously thought, resembling high density plasma lipoproteins. Results are discussed considering what is known on lipid metabolism in cestodes, and taken into account the Echinococcus spp. genomic information regarding both lipid metabolism and the EgAgB gene family. PMID:22616019

Lipids and Fatty Acids of Nudibranch Mollusks: Potential Sources of Bioactive Compounds

PubMed Central

Zhukova, Natalia V.

2014-01-01

The molecular diversity of chemical compounds found in marine animals offers a good chance for the discovery of novel bioactive compounds of unique structures and diverse biological activities. Nudibranch mollusks, which are not protected by a shell and produce chemicals for various ecological uses, including defense against predators, have attracted great interest for their lipid composition. Lipid analysis of eight nudibranch species revealed dominant phospholipids, sterols and monoalkyldiacylglycerols. Among polar lipids, 1-alkenyl-2-acyl glycerophospholipids (plasmalogens) and ceramide-aminoethyl phosphonates were found in the mollusks. The fatty acid compositions of the nudibranchs differed greatly from those of other marine gastropods and exhibited a wide diversity: very long chain fatty acids known as demospongic acids, a series of non-methylene-interrupted fatty acids, including unusual 21:2∆7,13, and an abundance of various odd and branched fatty acids typical of bacteria. Symbiotic bacteria revealed in some species of nudibranchs participate presumably in the production of some compounds serving as a chemical defense for the mollusks. The unique fatty acid composition of the nudibranchs is determined by food supply, inherent biosynthetic activities and intracellular symbiotic microorganisms. The potential of nudibranchs as a source of biologically active lipids and fatty acids is also discussed. PMID:25196731

Evidence of Cholesterol Accumulated in High Curvature Regions: Implication ot the Curvature Elastic Energy for Lipid Mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang,W.; Yang, L.; Huang, H.

2007-01-01

Recent experiments suggested that cholesterol and other lipid components of high negative spontaneous curvature facilitate membrane fusion. This is taken as evidence supporting the stalk-pore model of membrane fusion in which the lipid bilayers go through intermediate structures of high curvature. How do the high-curvature lipid components lower the free energy of the curved structure? Do the high-curvature lipid components modify the average spontaneous curvature of the relevant monolayer, thereby facilitate its bending, or do the lipid components redistribute in the curved structure so as to lower the free energy? This question is fundamental to the curvature elastic energy formore » lipid mixtures. Here we investigate the lipid distribution in a monolayer of a binary lipid mixture before and after bending, or more precisely in the lamellar, hexagonal, and distorted hexagonal phases. The lipid mixture is composed of 2:1 ratio of brominated di18:0PC and cholesterol. Using a newly developed procedure for the multiwavelength anomalous diffraction method, we are able to isolate the bromine distribution and reconstruct the electron density distribution of the lipid mixture in the three phases. We found that the lipid distribution is homogenous and uniform in the lamellar and hexagonal phases. But in the distorted hexagonal phase, the lipid monolayer has nonuniform curvature, and cholesterol almost entirely concentrates in the high curvature region. This finding demonstrates that the association energies between lipid molecules vary with the curvature of membrane. Thus, lipid components in a mixture may redistribute under conditions of nonuniform curvature, such as in the stalk structure. In such cases, the spontaneous curvature depends on the local lipid composition and the free energy minimum is determined by lipid distribution as well as curvature.« less

Performance of structured lipids incorporating selected phenolic and ascorbic acids.

PubMed

Gruczynska, Eliza; Przybylski, Roman; Aladedunye, Felix

2015-04-15

Conditions applied during frying require antioxidant which is stable at these conditions and provides protection for frying oil and fried food. Novel structured lipids containing nutraceuticals and antioxidants were formed by enzymatic transesterification, exploring canola oil and naturally occurring antioxidants such as ascorbic and selected phenolic acids as substrates. Lipozyme RM IM lipase from Rhizomucor miehei was used as biocatalyst. Frying performance and oxidative stability of the final transesterification products were evaluated. The novel lipids showed significantly improved frying performance compared to canola oil. Oxidative stability assessment of the structured lipids showed significant improvement in resistance to oxidative deterioration compared to original canola oil. Interestingly, the presence of ascorbic acid in an acylglycerol structure protected α-tocopherol against thermal degradation, which was not observed for the phenolic acids. Developed structured lipids containing nutraceuticals and antioxidants may directly affect nutritional properties of lipids also offering nutraceutical ingredients for food formulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

An Experimental Model to Study the Impact of Lipid Oxidation on Contact Lens Deposition In Vitro.

PubMed

Schuett, Burkhardt S; Millar, Thomas J

2017-09-01

This study was to establish a controlled in vitro test system to study the effect of lipid oxidation on lipid deposition on contact lenses. Fatty acids with varying degree of unsaturation were oxidized using the Fenton reaction. The degree of lipid oxidation and the lipid moieties formed during the oxidation were identified and estimated by various lipid staining techniques following separation with thin-layer chromatography, and by measuring thiobarbituric acid reactive substances or peroxides in solution. Two different silicone hydrogel-based contact lenses (Balafilcon A and Senofilcon A) were incubated with fatty acids laced with radioactive tracer oxidized to varying degrees, and the amount of lipid deposition was measured using unoxidized lipid samples as controls. The Fenton reaction together with the analytical methods to analyze the lipid oxidation can be used to control oxidation of lipids to a desired amount. In general, saturated fatty acids are not oxidized, the monounsaturated oleic acid produced peroxides while poly-unsaturated lipids initially produced peroxides and then fragmented into reactive aldehydes. Incubation with mildly oxidized lipids (most likely lipid peroxides) resulted in increased lipid deposition on Balafilcon A lenses compared to unoxidized lipids, but this was not observed for Senofilcon A lenses. Further oxidation of the lipids (carbon chain breakup) on the other hand resulted in diminished lipid deposition for both contact lens types. This study provides a method for inducing and controlling lipid oxidation so that the effect of lipid oxidation on contact lens binding can be compared. It could be shown that the degree of lipid oxidation has different effects on the lipid deposition on different contact lens types.

Lipid nanoparticle interactions and assemblies

NASA Astrophysics Data System (ADS)

Preiss, Matthew Ryan

Novel liposome-nanoparticle assemblies (LNAs) provide a biologically inspired route for designing multifunctional bionanotheranostics. LNAs combine the benefits of lipids and liposomes to encapsulate, transport, and protect hydrophilic and hydrophobic therapeutics with functional nanoparticles. Functional nanoparticles endow LNAs with additional capabilities, including the ability to target diseases, triggered drug release, controlled therapeutic output, and diagnostic capabilities to produce a drug delivery system that can effectively and efficiently deliver therapeutics while reducing side effects. Not only could LNAs make existing drugs better, they could also provide an avenue to allow once promising non-approved drugs (rejected due to harmful side effects, inadequate pharmacokinetics, and poor efficacy) to be safely used through targeted and controlled delivery directly to the diseased site. LNAs have the potential to be stimuli responsive, delivering drugs on command by external (ultrasound, RF heating, etc.) or internal (pH, blood sugar, heart rate, etc.) stimuli. Individually, lipids and nanoparticles have been clinically approved for therapy, such as Doxil (a liposomal doxorubicin for cancer treatment), and diagnosis, such as Feridex (an iron oxide nanoparticle an MRI contrast enhancement agent for liver tumors). In order to engineer these multifunctional LNAs for theranostic applications, the interactions between nanoparticles and lipids must be better understood. This research sought to explore the formation, design, structures, characteristics, and functions of LNAs. To achieve this goal, different types of LNAs were formed, specifically magnetoliposomes, bilayer decorated LNAs (DLNAs), and lipid-coated magnetic nanoparticles (LMNPs). A fluorescent probe was embedded in the lipid bilayer of magnetoliposomes allowing the local temperature and membrane fluidity to be observed. When subjected to an electromagnetic field that heated the encapsulated iron oxide nanoparticles encapsulated in the lipid bilayer, the local temperature and membrane fluidity could be observed. DLNAs were encapsulated with different sized nanoparticles and concentrations in order to observe the effect of the bilayer nanoparticles on the lipid bilayer's phase behavior and leakage. Two different sized nanoparticles were used, a 2 nm gold nanoparticle (GNP) much smaller than the thickness of the bilayer and a 4 nm GNP near the thickness of the lipid bilayer. The 2 nm GNPs were shown to affect the lipid bilayer differently than the 4 nm GNP. Specifically, the two nanoparticles altered the phase behavior and leakage differently in a temperature dependent fashion, demonstrating that embedded nanoparticle size can be used induce or inhibit bilayer leakage. A dual solvent exchange method was used to control the lipid surface composition of an iron oxide nanoparticle with a cationic lipid and a polyethylene glycol (PEG) lipid to produce lipid coated magnetic nanoparticles (LMNPs). PEG is well known for its ability to enhance the pharmacokinetics of nanostructures by preventing uptake by the immune system. By controlling the lipid surface composition, the surface charge and PEG conformation can be controlled which allowed the LMNPs to be used as an MRI contrast agent and a delivery system for siRNA that could be triggered with temperature.

Structural characterization of the lipid A region of Aeromonas salmonicida subsp. salmonicida lipopolysaccharide.

PubMed

Wang, Zhan; Li, Jianjun; Altman, Eleonora

2006-12-11

The lipid A components of Aeromonas salmonicida subsp. salmonicida from strains A449, 80204-1 and an in vivo rough isolate were isolated by mild acid hydrolysis of the lipopolysaccharide. Structural studies carried out by a combination of fatty acid, electrospray ionization-mass spectrometry and nuclear magnetic resonance analyses confirmed that the structure of lipid A was conserved among different isolates of A. salmonicida subsp. salmonicida. All analyzed strains contained three major lipid A molecules differing in acylation patterns corresponding to tetra-, penta- and hexaacylated lipid A species and comprising 4'-monophosphorylated beta-2-amino-2-deoxy-d-glucopyranose-(1-->6)-2-amino-2-deoxy-d-glucopyranose disaccharide, where the reducing end 2-amino-2-deoxy-d-glucose was present primarily in the alpha-pyranose form. Electrospray ionization-tandem mass spectrometry fragment pattern analysis, including investigation of the inner-ring fragmentation, allowed the localization of fatty acyl residues on the disaccharide backbone of lipid A. The tetraacylated lipid A structure containing 3-(dodecanoyloxy)tetradecanoic acid at N-2',3-hydroxytetradecanoic acid at N-2 and 3-hydroxytetradecanoic acid at O-3, respectively, was found. The pentaacyl lipid A molecule had a similar fatty acid distribution pattern and, additionally, carried 3-hydroxytetradecanoic acid at O-3'. In the hexaacylated lipid A structure, 3-hydroxytetradecanoic acid at O-3' was esterified with a secondary 9-hexadecenoic acid. Interestingly, lipid A of the in vivo rough isolate contained predominantly tetra- and pentaacylated lipid A species suggesting that the presence of the hexaacyl lipid A was associated with the smooth-form lipopolysaccharide.

Isolation and structure elucidation of avocado seed (Persea americana) lipid derivatives that inhibit Clostridium sporogenes endospore germination.

PubMed

Rodríguez-Sánchez, Dariana Graciela; Pacheco, Adriana; García-Cruz, María Isabel; Gutiérrez-Uribe, Janet Alejandra; Benavides-Lozano, Jorge Alejandro; Hernández-Brenes, Carmen

2013-07-31

Avocado fruit extracts are known to exhibit antimicrobial properties. However, the effects on bacterial endospores and the identity of antimicrobial compounds have not been fully elucidated. In this study, avocado seed extracts were tested against Clostridium sporogenes vegetative cells and active endospores. Bioassay-guided purification of a crude extract based on inhibitory properties linked antimicrobial action to six lipid derivatives from the family of acetogenin compounds. Two new structures and four compounds known to exist in nature were identified as responsible for the activity. Structurally, most potent molecules shared features of an acetyl moiety and a trans-enone group. All extracts produced inhibition zones on vegetative cells and active endospores. Minimum inhibitory concentrations (MIC) of isolated molecules ranged from 7.8 to 15.6 μg/mL, and bactericidal effects were observed for an enriched fraction at 19.5 μg/mL. Identified molecules showed potential as natural alternatives to additives and antibiotics used by the food and pharmaceutical industries to inhibit Gram-positive spore-forming bacteria.

Lipids of Dietzia sp. A14101. Part I: A study of the production dynamics of surface-active compounds.

PubMed

Hvidsten, Ina; Mjøs, Svein Are; Holmelid, Bjarte; Bødtker, Gunhild; Barth, Tanja

2017-11-01

Dietzia sp. A14101 belonging to the genus Dietzia (Gram-positive bacteria, Actinomycetes, high G+C content of DNA) was isolated from an oil reservoir model column inoculated with oil-field bacteria (Bødtker et al., 2009). Low interfacial tension (IFT) values were obtained by studying intact strain cells grown on water-immiscible hydrocarbons (HC) (Kowalewski et al. (2004), Kowalewski et al. (2005). Further investigations showed that the adaptation mechanism of Dietzia sp. A14101 to toxic water-immiscible HC involved changes both on the level of fatty acids content and in the physical properties of the cellular surface (development of the negative cellular surface charge and an increased in hydrophobicity) (Hvidsten et al., 2015b). However, these changes could not explain the low IFT values observed in earlier studies of this strain. Generally, low IFT imply a production of surface active compounds of low MW that are lipids by structure (Rosenberg and Ron, 1999). In this paper, it is shown that Dietzia sp. A14101 produces a range of glycolipids on all substrates. The amount of trehalose-containing lipids increases when the strain is grown on hydrocarbons. The production peak seems to coincide with the exponential growth phase, and such increased glycolipid synthesis continues throughout the stationary phase. The results indicate that only low amounts of the hydrocarbon substrate is incorporated directly into the glycolipids produced. Most of the hydrocarbon substrate seems to be employed for the biosynthesis of the neutral lipids and higher amounts of biomass were generated on HC substrates compared to incubations on non-HC substrates. The lipid content of the cell was determined as the total lipid extract (TLE), and was further fractionated (SPE). The hydrophobic and hydrophilic moieties of the isolated surface active compounds were determined (GC-MS, TLC, DART, LC-MS). The changes in the lipid content during the culture development were monitored by 1D and 2D TLC, emulsification and oil-spreading tests. Copyright © 2017 Elsevier B.V. All rights reserved.

Uptake and metabolism of structured triglyceride by Caco-2 cells: reversal of essential fatty acid deficiency.

PubMed

Spalinger, J H; Seidman, E G; Lepage, G; Ménard, D; Gavino, V; Levy, E

1998-10-01

Structured lipids have been proposed as efficient vehicles for the supplementation of essential fatty acids (EFA) to patients with malabsorption. We investigated how a novel structured triglyceride (STG), containing purely octanoic acid in the sn-1/sn-3 and [14C]linoleic acid in the sn-2 positions, was incorporated into different lipid classes in Caco-2 cells. We also evaluated the contribution of gastric lipase in the uptake and metabolism of [14C]linoleic acid from the STG. We furthermore determined the potential of the STG to correct EFA deficiency induced in Caco-2 cells. The absorption of STG by Caco-2 cells was significantly greater compared with that of triolein. The addition of human gastric lipase significantly enhanced cellular uptake of the labeled substrate, reflecting the stereoselectivity of gastric lipase to hydrolyze medium chain FA. Analysis of the intracellular lipids synthesized revealed a predominance of phospholipids-monoglycerides. Most of the radioactivity in the lipoproteins isolated from Caco-2 cells was recovered in TG-rich lipoproteins (45%) and to a lesser extent in the high-density lipoprotein (36%) and low-density lipoprotein (17%) fractions. The administration of STG to Caco-2 cells rendered EFA deficient produced a marked increase of the cellular level of linoleic and arachidonic acids. This resulted in a lower ratio of 20:3(n-9) to 20:4(n-6), reflecting the correction of EFA deficiency in Caco-2 cells. Our data demonstrate that STG, in the presence of gastric lipase, have beneficial effects on lipid incorporation, lipoprotein production, and EFA status, utilizing Caco-2 cells as a model of EFA deficiency.

Nutritional evaluation of structured lipid containing omega 6 fatty acid synthesized from coconut oil in rats.

PubMed

Rao, Reena; Lokesh, Belur R

2003-06-01

Coconut oil is rich in medium chain fatty acids, but deficient in polyunsaturated fatty acids (PUFA). Structured lipids (SL) enriched with omega 6 PUFA were synthesized from coconut oil triglycerides by employing enzymatic acidolysis with free fatty acids obtained from safflower oil. Rats were fed a diet containing coconut oil, coconut oil-safflower oil blend (1:0.7 w/ w) or structured lipid at 10% levels for a period of 60 days. The SL lowered serum cholesterol levels by 10.3 and 10.5% respectively in comparison with those fed coconut oil and blended oil. Similarly the liver cholesterol levels were also decreased by 35.9 and 26.6% respectively in animals fed structured lipids when compared to those fed on coconut oil or the blended oil. Most of the decrease observed in serum cholesterol levels of animals fed structured lipids was found in LDL fraction. The triglyceride levels in serum showed a decrease by 17.5 and 17.4% while in the liver it was reduced by 45.8 and 23.5% in the structured lipids fed animals as compared to those fed coconut oil or blended oil respectively. Differential scanning calorimetric studies indicated that structured lipids had lower melting points and solid fat content when compared to coconut oil or blended oils. These studies indicated that enrichment of coconut oil triglycerides with omega 6 fatty acids lowers its solid fat content. The omega 6 PUFA enriched structured lipids also exhibited hypolipidemic activity.

Multiscale structures of lipids in foods as parameters affecting fatty acid bioavailability and lipid metabolism.

PubMed

Michalski, M C; Genot, C; Gayet, C; Lopez, C; Fine, F; Joffre, F; Vendeuvre, J L; Bouvier, J; Chardigny, J M; Raynal-Ljutovac, K

2013-10-01

On a nutritional standpoint, lipids are now being studied beyond their energy content and fatty acid (FA) profiles. Dietary FA are building blocks of a huge diversity of more complex molecules such as triacylglycerols (TAG) and phospholipids (PL), themselves organised in supramolecular structures presenting different thermal behaviours. They are generally embedded in complex food matrixes. Recent reports have revealed that molecular and supramolecular structures of lipids and their liquid or solid state at the body temperature influence both the digestibility and metabolism of dietary FA. The aim of the present review is to highlight recent knowledge on the impact on FA digestion, absorption and metabolism of: (i) the intramolecular structure of TAG; (ii) the nature of the lipid molecules carrying FA; (iii) the supramolecular organization and physical state of lipids in native and formulated food products and (iv) the food matrix. Further work should be accomplished now to obtain a more reliable body of evidence and integrate these data in future dietary recommendations. Additionally, innovative lipid formulations in which the health beneficial effects of either native or recomposed structures of lipids will be taken into account can be foreseen. Copyright © 2013 Elsevier Ltd. All rights reserved.

Structure—activity relationships for insecticidal carbamates*

PubMed Central

Metcalf, Robert L.

1971-01-01

Carbamate insecticides are biologically active because of their structural complementarity to the active site of acetylcholinesterase (AChE) and their consequent action as substrates with very low turnover numbers. Carbamates behave as synthetic neurohormones that produce their toxic action by interrupting the normal action of AChE so that acetylcholine accumulates at synaptic junctions. The necessary properties for a suitable insecticidal carbamate are lipid solubility, suitable structural complementarity to AChE, and sufficient stability to multifunction-oxidase detoxification. The relationships between the structure and the activity of a large number of synthetic carbamates are analysed in detail, with particular attention to the second of these properties. PMID:5315358

An acpXL Mutant of Rhizobium leguminosarum bv. phaseoli Lacks 27-Hydroxyoctacosanoic Acid in Its Lipid A and Is Developmentally Delayed during Symbiotic Infection of the Determinate Nodulating Host Plant Phaseolus vulgaris ▿

PubMed Central

Brown, Dusty B.; Huang, Yu-Chu; Kannenberg, Elmar L.; Sherrier, D. Janine; Carlson, Russell W.

2011-01-01

Rhizobium leguminosarum is a Gram-negative bacterium that forms nitrogen-fixing symbioses with compatible leguminous plants via intracellular invasion and establishes a persistent infection within host membrane-derived subcellular compartments. Notably, an unusual very-long-chain fatty acid (VLCFA) is found in the lipid A of R. leguminosarum as well as in the lipid A of the medically relevant pathogens Brucella abortus, Brucella melitensis, Bartonella henselae, and Legionella pneumophila, which are also able to persist within intracellular host-derived membranes. These bacterial symbionts and pathogens each contain a homologous gene region necessary for the synthesis and transfer of the VLCFA to the lipid A. Within this region lies a gene that encodes the specialized acyl carrier protein AcpXL, on which the VLCFA is built. This study describes the biochemical and infection phenotypes of an acpXL mutant which lacks the VLCFA. The mutation was created in R. leguminosarum bv. phaseoli strain 8002, which forms symbiosis with Phaseolus vulgaris, a determinate nodulating legume. Structural analysis using gas chromatography and mass spectrometry revealed that the mutant lipid A lacked the VLCFA. Compared to the parent strain, the mutant was more sensitive to the detergents deoxycholate and dodecyl sulfate and the antimicrobial peptide polymyxin B, suggesting a compromise to membrane stability. In addition, the mutant was more sensitive to higher salt concentrations. Passage through the plant restored salt tolerance. Electron microscopic examination showed that the mutant was developmentally delayed during symbiotic infection of the host plant Phaseolus vulgaris and produced abnormal symbiosome structures. PMID:21764936

An acpXL mutant of Rhizobium leguminosarum bv. phaseoli lacks 27-hydroxyoctacosanoic acid in its lipid A and is developmentally delayed during symbiotic infection of the determinate nodulating host plant Phaseolus vulgaris.

PubMed

Brown, Dusty B; Huang, Yu-Chu; Kannenberg, Elmar L; Sherrier, D Janine; Carlson, Russell W

2011-09-01

Rhizobium leguminosarum is a Gram-negative bacterium that forms nitrogen-fixing symbioses with compatible leguminous plants via intracellular invasion and establishes a persistent infection within host membrane-derived subcellular compartments. Notably, an unusual very-long-chain fatty acid (VLCFA) is found in the lipid A of R. leguminosarum as well as in the lipid A of the medically relevant pathogens Brucella abortus, Brucella melitensis, Bartonella henselae, and Legionella pneumophila, which are also able to persist within intracellular host-derived membranes. These bacterial symbionts and pathogens each contain a homologous gene region necessary for the synthesis and transfer of the VLCFA to the lipid A. Within this region lies a gene that encodes the specialized acyl carrier protein AcpXL, on which the VLCFA is built. This study describes the biochemical and infection phenotypes of an acpXL mutant which lacks the VLCFA. The mutation was created in R. leguminosarum bv. phaseoli strain 8002, which forms symbiosis with Phaseolus vulgaris, a determinate nodulating legume. Structural analysis using gas chromatography and mass spectrometry revealed that the mutant lipid A lacked the VLCFA. Compared to the parent strain, the mutant was more sensitive to the detergents deoxycholate and dodecyl sulfate and the antimicrobial peptide polymyxin B, suggesting a compromise to membrane stability. In addition, the mutant was more sensitive to higher salt concentrations. Passage through the plant restored salt tolerance. Electron microscopic examination showed that the mutant was developmentally delayed during symbiotic infection of the host plant Phaseolus vulgaris and produced abnormal symbiosome structures. Copyright © 2011, American Society for Microbiology. All Rights Reserved.

Prevalence of the equol-producer phenotype and its relationship with dietary isoflavone and serum lipids in healthy Chinese adults.

PubMed

Liu, Baohua; Qin, Liqiang; Liu, Aiping; Uchiyama, Shigeto; Ueno, Tomomi; Li, Xuetuo; Wang, Peiyu

2010-01-01

Studies have suggested that daidzein-metabolizing phenotypes have beneficial effects on a range of health outcomes. We investigated the prevalence of equol producers and the relationship of equol phenotype with habitual isoflavone consumption and serum lipid concentrations in 200 Chinese adults in Beijing. After the baseline survey and dietary records, 200 healthy adults in Beijing were challenged with a soy-isoflavone supplement for 3 days; 24-hour urine samples were collected before and after the challenge. Isoflavones and their metabolites in urine were measured to determine equol phenotype. Serum lipids, uric acid, and other biochemical markers were also measured. Only 26.8% of the participants excreted equol when on a regular diet, as compared with 60.4% after the challenge. After the challenge, urinary isoflavonoid excretion increased in all participants, while equol excretion increased only in equol producers. Isoflavone intake was correlated with urinary isoflavone (range r = 0.49-0.58, P < 0.01). As compared with nonproducers, equol producers were less likely to consume cereals (P < 0.001). There was no significant correlation between serum lipids and isoflavone intake. Serum lipids were not significantly affected by equol phenotype. Urinary equol excretion was detected in about 25% of participants under their usual dietary conditions. Their potential to produce equol was increased after the challenge. Urinary isoflavone levels may serve as a useful biomarker for isoflavone intake in populations. We observed an association between equol phenotype and cereal intake. Our findings also suggest that dietary isoflavone intake has no significant effect on serum lipids in healthy participants, regardless of equol phenotype.

Microorganism Utilization for Synthetic Milk Production

NASA Technical Reports Server (NTRS)

Morford, Megan A.; Khodadad, Christina Louise; Spencer, LaShelle E.; Richards, Jeffrey T.; Strayer, Richard F.; Caro, Janicce; Hummerick, Mary; Birmele, Michele N.; Wheeler, Raymond M.

2014-01-01

A desired architecture for long duration spaceflight, such as aboard the International Space Station (ISS) or for future missions to Mars, is to provide a supply of fresh food crops for the astronauts. However, some crops can create a high proportion of inedible plant waste. The main goal of this project was to produce the components of milk (sugar, lipid, protein) from inedible plant waste by utilizing microorganisms (fungi, yeast, bacteria). Of particular interest was utilizing the valuable polysaccharide, cellulose, found in plant waste, to naturally fuel- through microorganism cellular metabolism- the creation of sugar (glucose), lipid (milk fat), and protein (casein) to produce a synthetic edible food product. Environmental conditions such as pH, temperature, carbon source, aeration, and choice microorganisms were optimized in the laboratory and the desired end-products, sugars and lipids, were analyzed. Trichoderma reesei, a known cellulolytic fungus, was utilized to drive the production of glucose, with the intent that the produced glucose would serve as the carbon source for milk fat production and be a substitute for the milk sugar lactose. Lipid production would be carried out by Rhodosporidium toruloides, yeast known to accumulate those lipids that are typically found in milk fat. Results showed that glucose and total lipid content were below what was expected during this phase of experimentation. In addition, individual analysis of six fatty acids revealed that the percentage of each fatty acid was lower than naturally produced bovine milk. Overall, this research indicates that microorganisms could be utilized to breakdown inedible solid waste to produce useable products.

Biodiesel production by various oleaginous microorganisms from organic wastes.

PubMed

Cho, Hyun Uk; Park, Jong Moon

2018-05-01

Biodiesel is a biodegradable and renewable fuel. A large amount of research has considered microbial oil production using oleaginous microorganisms, but the commercialization of microbial lipids produced in this way remains uncertain due to the high cost of feedstock or low lipid yield. Microbial lipids can be typically produced by microalgae, yeasts, and bacteria; the lipid yields of these microorganisms can be improved by using sufficient concentrations of organic carbon sources. Therefore, combining low-cost organic compounds contained in organic wastes with cultivation of oleaginous microorganisms can be a promising approach to obtain commercial viability. However, to achieve effective bioconversion of low-cost substrates to microbial lipids, the characteristics of each microorganism and each substrate should be considered simultaneously. This article discusses recent approaches to developing cost-effective microbial lipid production processes that use various oleaginous microorganisms and organic wastes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mixing, diffusion, and percolation in binary supported membranes containing mixtures of lipids and amphiphilic block copolymers.

PubMed

Gettel, Douglas L; Sanborn, Jeremy; Patel, Mira A; de Hoog, Hans-Peter; Liedberg, Bo; Nallani, Madhavan; Parikh, Atul N

2014-07-23

Substrate-mediated fusion of small polymersomes, derived from mixtures of lipids and amphiphilic block copolymers, produces hybrid, supported planar bilayers at hydrophilic surfaces, monolayers at hydrophobic surfaces, and binary monolayer/bilayer patterns at amphiphilic surfaces, directly responding to local measures of (and variations in) surface free energy. Despite the large thickness mismatch in their hydrophobic cores, the hybrid membranes do not exhibit microscopic phase separation, reflecting irreversible adsorption and limited lateral reorganization of the polymer component. With increasing fluid-phase lipid fraction, these hybrid, supported membranes undergo a fluidity transition, producing a fully percolating fluid lipid phase beyond a critical area fraction, which matches the percolation threshold for the immobile point obstacles. This then suggests that polymer-lipid hybrid membranes might be useful models for studying obstructed diffusion, such as occurs in lipid membranes containing proteins.

Genomic Prospecting for Microbial Biodiesel Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lykidis, Athanasios; Lykidis, Athanasios; Ivanova, Natalia

2008-03-20

Biodiesel is defined as fatty acid mono-alkylesters and is produced from triacylglycerols. In the current article we provide an overview of the structure, diversity and regulation of the metabolic pathways leading to intracellular fatty acid and triacylglycerol accumulation in three types of organisms (bacteria, algae and fungi) of potential biotechnological interest and discuss possible intervention points to increase the cellular lipid content. The key steps that regulate carbon allocation and distribution in lipids include the formation of malonyl-CoA, the synthesis of fatty acids and their attachment onto the glycerol backbone, and the formation of triacylglycerols. The lipid biosynthetic genes andmore » pathways are largely known for select model organisms. Comparative genomics allows the examination of these pathways in organisms of biotechnological interest and reveals the evolution of divergent and yet uncharacterized regulatory mechanisms. Utilization of microbial systems for triacylglycerol and fatty acid production is in its infancy; however, genomic information and technologies combined with synthetic biology concepts provide the opportunity to further exploit microbes for the competitive production of biodiesel.« less

Molecular and enzymatic characterization of alkaline lipase from Bacillus amyloliquefaciens E1PA isolated from lipid-rich food waste.

PubMed

Saengsanga, Thanakorn; Siripornadulsil, Wilailak; Siripornadulsil, Surasak

2016-01-01

Bacillus amyloliquefaciens E1PA is a lipase-producing strain that was originally isolated from lipid-rich food waste, and the production of its lipase was found to be induced by vegetable oils. The E1PA lipase was successfully expressed and secreted in a heterologous Escherichia coli host and was ultimately purified. The conserved pentapeptide motif Ala-His-Ser-Met-Gly was observed at positions 108-112. The purified recombinant lipase was stable over a pH range of 4.0-11.0 at 40 °C and exhibited maximal activity at pH 10. The recombinant E1PA lipase hydrolyzed a wide range of acyl esters (C4-C18). However, the highest activity (3.5 units mg(-1)) was observed when the p-nitrophenyl ester of myristate (C14) was used as a substrate. Compared to the lipases produced by Bacillus spp., the E1PA lipase displayed a structural molecular mass excluding the leader sequence (19.22 kDa) and a pI (9.82) that were similar to those reported for B. amyloliquefaciens lipases and lipase subfamily I.4 but that were quite distinct from those of lipase subfamily I.5 (approximately 43 kDa, pI 6). These results suggested that Bacillus lipases are closely related. Although the recombinant E1PA lipase digested only certain oils, the wild-type E1PA lipase degraded a variety of oils, including blended and re-used cooking oils. The recombinant and wild-type forms of the E1PA lipase were able to digest heterogeneous lipid-rich food waste at similar levels; this result suggests that this lipase can function even when it solely consists of its structural enzyme component. The enzyme exhibited lipid hydrolysis ability as either an intracellular domain of the recombinant protein or an extracellular domain secreted by the E1PA strain. However, the recombinant lipase showed higher activity than the wild-type E1PA lipase, indicating that the recombinant protein from E. coli possessed effective lipase activity. Thus, the inducible alkaline E1PA lipase exhibited the ability to act on a broad spectrum of substrates, and the effective form produced in the heterogeneous host can be further developed for several applications, such as biodiesel production and lipase production. Copyright © 2015 Elsevier Inc. All rights reserved.

The simulation approach to lipid-protein interactions.

PubMed

Paramo, Teresa; Garzón, Diana; Holdbrook, Daniel A; Khalid, Syma; Bond, Peter J

2013-01-01

The interactions between lipids and proteins are crucial for a range of biological processes, from the folding and stability of membrane proteins to signaling and metabolism facilitated by lipid-binding proteins. However, high-resolution structural details concerning functional lipid/protein interactions are scarce due to barriers in both experimental isolation of native lipid-bound complexes and subsequent biophysical characterization. The molecular dynamics (MD) simulation approach provides a means to complement available structural data, yielding dynamic, structural, and thermodynamic data for a protein embedded within a physiologically realistic, modelled lipid environment. In this chapter, we provide a guide to current methods for setting up and running simulations of membrane proteins and soluble, lipid-binding proteins, using standard atomistically detailed representations, as well as simplified, coarse-grained models. In addition, we outline recent studies that illustrate the power of the simulation approach in the context of biologically relevant lipid/protein interactions.

Cancer cells incorporate and remodel exogenous palmitate into structural and oncogenic signaling lipids.

PubMed

Louie, Sharon M; Roberts, Lindsay S; Mulvihill, Melinda M; Luo, Kunxin; Nomura, Daniel K

2013-10-01

De novo lipogenesis is considered the primary source of fatty acids for lipid synthesis in cancer cells, even in the presence of exogenous fatty acids. Here, we have used an isotopic fatty acid labeling strategy coupled with metabolomic profiling platforms to comprehensively map palmitic acid incorporation into complex lipids in cancer cells. We show that cancer cells and tumors robustly incorporate and remodel exogenous palmitate into structural and oncogenic glycerophospholipids, sphingolipids, and ether lipids. We also find that fatty acid incorporation into oxidative pathways is reduced in aggressive human cancer cells, and instead shunted into pathways for generating structural and signaling lipids. Our results demonstrate that cancer cells do not solely rely on de novo lipogenesis, but also utilize exogenous fatty acids for generating lipids required for proliferation and protumorigenic lipid signaling. This article is part of a special issue entitled Lipid Metabolism in Cancer. © 2013.

Synthesis and in vitro transfection efficiency of spermine-based cationic lipids with different central core structures and lipophilic tails.

PubMed

Niyomtham, Nattisa; Apiratikul, Nuttapon; Suksen, Kanoknetr; Opanasopit, Praneet; Yingyongnarongkul, Boon-Ek

2015-02-01

Twelve spermine-based cationic lipids with four different central core structures (di(oxyethyl)amino, di(oxyethyl)amino carboxy, 3-amino-1,2-dioxypropyl and 2-amino-1,3-dioxypropyl) and three hydrophobic tails (lauric acid, myristic acid and palmitic acid) were synthesized. The liposomes containing lipids and DOPE showed moderate to good in vitro DNA delivery into HeLa cells. GFP expression experiments revealed that liposomes composed of lipids with 3-amino-1,2-dioxypropyl as a central core structure exhibited highest transfection efficiency under serum-free condition. Whereas, lipid with 2-amino-1,3-dioxypropyl core structure showed highest transfection under 10% serum condition. Moreover, the liposomes and lipoplexes composted of these cationic lipids exhibited low cytotoxicity. Copyright © 2015. Published by Elsevier Ltd.

Design, Synthesis, and Characterization of Novel Zwitterionic Lipids for Drug and siRNA Delivery Applications

NASA Astrophysics Data System (ADS)

Walsh, Colin L.

Lipid-based nanoparticles have long been used to deliver biologically active molecules such as drugs, proteins, peptides, DNA, and siRNA in vivo. Liposomes and lipoplexes alter the biodistribution, pharmacokinetics, and cellular uptake of their encapsulated or associated cargo. This can increase drug efficacy while reducing toxicity, resulting in an increased therapeutic index and better clinical outcomes. Unlike small molecule drugs, which passively diffuse through lipid membranes, nucleic acids and proteins require an active, carrier mediated escape mechanism to reach their site of action. As such, the therapeutic application and drug properties dictate the required biophysical characteristics of the lipid nanoparticle. These carrier properties depend on the structure and biophysical characteristics of the lipids and other components used to formulate them. This dissertation presents a series of studies related to the development of novel synthetic lipids for use in drug delivery systems. First, we developed a novel class of zwitterionic lipids with head groups containing a cationic amine and anionic carboxylate and ester-linked oleic acid tails. These lipids exhibit structure-dependent, pH-responsive biophysical properties, and may be useful components for next-generation drug delivery systems. Second, we extended the idea of amine/carboxylate containing zwitterionic head groups and synthesized a series of acetate terminated diacyl lipids containing a quaternary amine. These lipids have an inverted headgroup orientation compared to naturally occurring zwitterionic lipids, and show interesting salt-dependent biophysical properties. Third, we synthesized and characterized a focused library of ionizable lysine-based lipids, which contain a lysine head group linked to a long-chain dialkylamine. A focused library was synthesized to determine the impact of hydrophobic fluidity, lipid net charge, and lipid pKa on the biophysical and siRNA transfection characteristics of these lipids. Our results indicate that structural variations significantly impact the biophysical and transfection behavior of this class of lipids. In summary, we have synthesized several new classes of lipids with biophysical characteristics that may be useful for drug delivery applications. Our results show that slight modifications to lipid structure impacts their biophysical behavior, which in turn dictates their potential utility in drug delivery systems. Further understanding lipid structure-activity relationships will allow for the rational design and engineering of lipids with appropriate properties for specific delivery applications.

Phase transition of a DPPC bilayer induced by an external surface pressure: from bilayer to monolayer behavior. a molecular dynamics simulation study.

PubMed

López Cascales, J J; Otero, T F; Fernandez Romero, A J; Camacho, L

2006-06-20

Understanding the lipid phase transition of lipid bilayers is of great interest from biophysical, physicochemical, and technological points of view. With the aim of elucidating the structural changes that take place in a DPPC phospholipid bilayer induced by an external isotropic surface pressure, five computer simulations were carried out in a range from 0.1 to 40 mN/m. Molecular dynamics simulations provided insight into the structural changes that took place in the lipid structure. It was seen that low pressures ranging from 0.1 to 1 mN/m had hardly any effect on the structure, electrical properties, or hydration of the lipid bilayer. However, for pressures above 40 mN/m, there was a sharp change in the lipid-lipid interactions, hydrocarbon lipid fluidity, and electrostatic potential, corresponding to the mesomorphic transition from a liquid crystalline state (L(alpha)) to its gel state (P'(beta)). The head lipid orientation remained almost unaltered, parallel to the lipid layer, as the surface pressure was increased, although a noticeable change in its angular distribution function was evident with the phase transition.

Functional reconstitution of the Mycobacterium tuberculosis long-chain acyl-CoA carboxylase from multiple acyl-CoA subunits.

PubMed

Bazet Lyonnet, Bernardo; Diacovich, Lautaro; Gago, Gabriela; Spina, Lucie; Bardou, Fabienne; Lemassu, Anne; Quémard, Annaïk; Gramajo, Hugo

2017-04-01

Mycobacterium tuberculosis produces a large number of structurally diverse lipids that have been implicated in the pathogenicity, persistence and antibiotic resistance of this organism. Most building blocks involved in the biosynthesis of all these lipids are generated by acyl-CoA carboxylases whose subunit composition and physiological roles have not yet been clearly established. Inconclusive data in the literature refer to the exact protein composition and substrate specificity of the enzyme complex that produces the long-chain α-carboxy-acyl-CoAs, which are substrates involved in the last step of condensation mediated by the polyketide synthase 13 to synthesize mature mycolic acids. Here we have successfully reconstituted the long-chain acyl-CoA carboxylase (LCC) complex from its purified components, the α subunit (AccA3), the ε subunit (AccE5) and the two β subunits (AccD4 and AccD5), and demonstrated that the four subunits are essential for its activity. Furthermore, we also showed by substrate competition experiments and the use of a specific inhibitor that the AccD5 subunit's role in the carboxylation of the long acyl-CoAs, as part of the LCC complex, was structural rather than catalytic. Moreover, AccD5 was also able to carboxylate its natural substrates, acetyl-CoA and propionyl-CoA, in the context of the LCC enzyme complex. Thus, the supercomplex formed by these four subunits has the potential to generate the main substrates, malonyl-CoA, methylmalonyl-CoA and α-carboxy-C 24-26 -CoA, used as condensing units for the biosynthesis of all the lipids present in this pathogen. © 2017 Federation of European Biochemical Societies.

Perilipin-related protein regulates lipid metabolism in C. elegans.

PubMed

Chughtai, Ahmed Ali; Kaššák, Filip; Kostrouchová, Markéta; Novotný, Jan Philipp; Krause, Michael W; Saudek, Vladimír; Kostrouch, Zdenek; Kostrouchová, Marta

2015-01-01

Perilipins are lipid droplet surface proteins that contribute to fat metabolism by controlling the access of lipids to lipolytic enzymes. Perilipins have been identified in organisms as diverse as metazoa, fungi, and amoebas but strikingly not in nematodes. Here we identify the protein encoded by the W01A8.1 gene in Caenorhabditis elegans as the closest homologue and likely orthologue of metazoan perilipin. We demonstrate that nematode W01A8.1 is a cytoplasmic protein residing on lipid droplets similarly as human perilipins 1 and 2. Downregulation or elimination of W01A8.1 affects the appearance of lipid droplets resulting in the formation of large lipid droplets localized around the dividing nucleus during the early zygotic divisions. Visualization of lipid containing structures by CARS microscopy in vivo showed that lipid-containing structures become gradually enlarged during oogenesis and relocate during the first zygotic division around the dividing nucleus. In mutant embryos, the lipid containing structures show defective intracellular distribution in subsequent embryonic divisions and become gradually smaller during further development. In contrast to embryos, lipid-containing structures in enterocytes and in epidermal cells of adult animals are smaller in mutants than in wild type animals. Our results demonstrate the existence of a perilipin-related regulation of fat metabolism in nematodes and provide new possibilities for functional studies of lipid metabolism.

Structural Diversity of Arthropod Biophotonic Nanostructures Spans Amphiphilic Phase-Space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saranathan, Vinod Kumar; Seago, Ainsley E.; Sandy, Alec

2015-05-04

Many organisms, especially arthropods, produce vivid interference colors using diverse mesoscopic (100-350 nm) integumentary biophotonic nanostructures that are increasingly being investigated for technological applications. Despite a century of interest, precise structural knowledge of many biophotonic nanostructures and the mechanisms controlling their development remain tentative, when such knowledge can open novel biomimetic routes to facilely self-assemble tunable, multifunctional materials. Here, we use synchrotron small-angle X-ray scattering and electron microscopy to characterize the photonic nanostructure of 140 integumentary scales and setae from ~127 species of terrestrial arthropods in 85 genera from 5 orders. We report a rich nanostructural diversity, including triply periodicmore » bicontinuous networks, close-packed spheres, inverse columnar, perforated lamellar, and disordered spongelike morphologies, commonly observed as stable phases of amphiphilic surfactants, block copolymer, and lyotropic lipid-water systems. Diverse arthropod lineages appear to have independently evolved to utilize the self-assembly of infolding lipid-bilayer membranes to develop biophotonic nanostructures that span the phase-space of amphiphilic morphologies, but at optical length scales.« less

Giant MACPF/CDC pore forming toxins: A class of their own.

PubMed

Reboul, Cyril F; Whisstock, James C; Dunstone, Michelle A

2016-03-01

Pore Forming Toxins (PFTs) represent a key mechanism for permitting the passage of proteins and small molecules across the lipid membrane. These proteins are typically produced as soluble monomers that self-assemble into ring-like oligomeric structures on the membrane surface. Following such assembly PFTs undergo a remarkable conformational change to insert into the lipid membrane. While many different protein families have independently evolved such ability, members of the Membrane Attack Complex PerForin/Cholesterol Dependent Cytolysin (MACPF/CDC) superfamily form distinctive giant β-barrel pores comprised of up to 50 monomers and up to 300Å in diameter. In this review we focus on recent advances in understanding the structure of these giant MACPF/CDC pores as well as the underlying molecular mechanisms leading to their formation. Commonalities and evolved variations of the pore forming mechanism across the superfamily are discussed. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale. Copyright © 2015 Elsevier B.V. All rights reserved.

Encapsulation with structured triglycerides

USDA-ARS?s Scientific Manuscript database

Lipids provide excellent materials to encapsulate bioactive compounds for food and pharmaceutical applications. Lipids are renewable, biodegradable, and easily modified to provide additional chemical functionality. The use of structured lipids that have been modified with photoactive properties are ...

Characterization of oilseed lipids from "DHA-producing Camelina sativa": a new transformed land plant containing long-chain omega-3 oils.

PubMed

Mansour, Maged P; Shrestha, Pushkar; Belide, Srinivas; Petrie, James R; Nichols, Peter D; Singh, Surinder P

2014-02-21

New and sustainable sources of long-chain (LC, ≥C₂₀) omega-3 oils containing DHA (docosahexaenoic acid, 22:6ω3) are required to meet increasing demands. The lipid content of the oilseed of a novel transgenic, DHA-producing land plant, Camelina sativa, containing microalgal genes able to produce LC omega-3 oils, contained 36% lipid by weight with triacylglycerols (TAG) as the major lipid class in hexane extracts (96% of total lipid). Subsequent chloroform-methanol (CM) extraction recovered further lipid (~50% polar lipid, comprising glycolipids and phospholipids) and residual TAG. The main phospholipid species were phosphatidyl choline and phosphatidyl ethanolamine. The % DHA was: 6.8% (of total fatty acids) in the TAG-rich hexane extract and 4.2% in the polar lipid-rich CM extract. The relative level of ALA (α-linolenic acid, 18:3ω3) in DHA-camelina seed was higher than the control. Major sterols in both DHA- and control camelina seeds were: sitosterol, campesterol, cholesterol, brassicasterol and isofucosterol. C₁₆-C₂₂ fatty alcohols, including iso-branched and odd-chain alcohols were present, including high levels of iso-17:0, 17:0 and 19:0. Other alcohols present were: 16:0, iso-18:0, 18:0 and 18:1 and the proportions varied between the hexane and CM extracts. These iso-branched odd-chain fatty alcohols, to our knowledge, have not been previously reported. These components may be derived from wax esters, or free fatty alcohols.

Rapid fabrication of three-dimensional structures for dielectrophoretic sorting of lipid-containing organisms

NASA Astrophysics Data System (ADS)

Schor, Alisha R.; Buie, Cullen R.

2016-10-01

In this work, we demonstrate a microfluidic particle sorter consisting of three-dimensional, conducting microposts. Our sorter uses dielectrophoresis (DEP) to sort high- and low-lipid phenotypes of the yeast Yarrowia lipolytica. Y. lipolytica is one of the many microorganisms being explored as a hydrocarbon source for biodiesel, Omega-3 additives, and other products derived from fatty acids. A rapid, non-destructive, lipid-based sorting tool would accelerate the commercialization of these products. Our device consists of an array of 105, 25 μm wide gold microposts that span the height of a 15 μm channel. This array generates an electric field in a microfluidic device that is uniform through the channel height, but has a custom-shaped non-uniformity in the horizontal directions. This is crucial in order to achieve continuous sorting using DEP, as it ensures all cells are exposed to the same conditions throughout the channel height. By using very low currents (100 μA), we are able to electroplate these post arrays in fewer than 15 min. This is an order of magnitude improvement over previous reports of electroplated microstructures. With an applied signal of 250 MHz, 2.6 V pp in our device, we separate a heterogeneous population with a purity of 97.8% in the low-lipid stream and 71.4% in the high-lipid stream. The high-lipid stream purity can be improved by adjusting the spacing of the array. This unique protocol for the rapid fabrication of 3D microstructures has enabled the creation of a non-invasive sorting tool for genetically engineered, lipid-producing organisms. The ability to screen organisms based on lipid content will alleviate one of the major bottlenecks in commercialization of microbial biofuels.

Docosapentaenoic acid (DPA) is a critical determinant of cubic membrane formation in amoeba Chaos mitochondria.

PubMed

Deng, Yuru; Almsherqi, Zakaria A; Shui, Guanghou; Wenk, Markus R; Kohlwein, Sepp D

2009-09-01

Very long-chain polyunsaturated fatty acids (VLC-PUFAs), such as docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA), have recently made it to the realm of "magical molecules" based on their multiple presumably beneficial effects in biological systems, making these PUFAs particularly interesting in biomedicine. Their specific biological functions, however, remain enigmatic. Here we provide evidence derived from studies in the amoeba Chaos that indicates a structural role for omega-6 DPA in cell membrane organization, which may help to explain the multiple diverse effects of VLC-PUFA in healthy and diseased states. Amoeba Chaos mitochondria undergo a remarkable and reversible morphological transition into cubic morphology on starvation. This morphological transition is reflected in major changes in fatty acid and lipid composition, as determined by gas liquid chromatography and mass spectrometry, in particular by a drastic increase in C22:5 modified phosphatidylcholine plasmalogen, phosphatidylethanolamine plasmalogen, and phosphatidylinositol species. Liposomes produced in vitro from lipids of starved amoeba cells show a high propensity to form hexagonal tubular and cubic morphologies. Addition of omega-6 DPA, but not of omega-3 DPA, to the cell culture also induced mitochondrial membrane transformation into cubic morphology in fed cells, demonstrating for the first time an important structural role of omega-6 DPA-containing lipids in cell membrane organization.

On the optimal design of molecular sensing interfaces with lipid bilayer assemblies - A knowledge based approach

NASA Astrophysics Data System (ADS)

Siontorou, Christina G.

2012-12-01

Biosensors are analytic devices that incorporate a biochemical recognition system (biological, biologicalderived or biomimic: enzyme, antibody, DNA, receptor, etc.) in close contact with a physicochemical transducer (electrochemical, optical, piezoelectric, conductimetric, etc.) that converts the biochemical information, produced by the specific biological recognition reaction (analyte-biomolecule binding), into a chemical or physical output signal, related to the concentration of the analyte in the measuring sample. The biosensing concept is based on natural chemoreception mechanisms, which are feasible over/within/by means of a biological membrane, i.e., a structured lipid bilayer, incorporating or attached to proteinaceous moieties that regulate molecular recognition events which trigger ion flux changes (facilitated or passive) through the bilayer. The creation of functional structures that are similar to natural signal transduction systems, correlating and interrelating compatibly and successfully the physicochemical transducer with the lipid film that is self-assembled on its surface while embedding the reconstituted biological recognition system, and at the same time manage to satisfy the basic conditions for measuring device development (simplicity, easy handling, ease of fabrication) is far from trivial. The aim of the present work is to present a methodological framework for designing such molecular sensing interfaces, functioning within a knowledge-based system built on an ontological platform for supplying sub-systems options, compatibilities, and optimization parameters.

Synthesis of 1,3-dioleoyl-2-arachidonoylglycerol-rich structured lipids by lipase-catalyzed acidolysis of microbial oil from Mortierella alpina.

PubMed

Abed, Sherif M; Zou, Xiaoqiang; Ali, Abdelmoneim H; Jin, Qingzhe; Wang, Xingguo

2017-11-01

Microbial oils (MOs) have gained widespread attention due to their functional lipids and health promoting properties. In this study, 1,3-dioleoyl-2-arachidonoylglycerol-rich structured lipids (SLs) were produced from MO and oleic acid (OA) via solvent-free acidolysis catalyzed by Lipozyme RM IM. Under the optimal conditions, the content of unsaturated fatty acids (UFAs) increased from 60.63 to 84.00%, while the saturated fatty acids (SFAs) content decreased from 39.37 to 16.00% at sn-1,3 positions in SLs. Compared with MO, arachidonic acid (ARA) content at the sn-2 position of SLs accounted for 49.71%, whereas OA was predominantly located at sn-1,3 positions (47.05%). Meanwhile, the most abundant triacylglycerol (TAG) species in SLs were (18:1-20:4-18:1), (20:4-20:4-18:1), (18:1-18:2-18:1), (18:1-18:2-18:0) and (24:0-20:4-18:1) with a relative content of 18.79%, 11.94%, 6.07%, 5.75% and 4.84%, respectively. Such novel SLs with improved functional properties enriched with UFAs are highly desirable and have the potential to be used in infant formula. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lipid and DNA biomarker analyses of Narragansett Bay Sediments: Evaluating the UK'37 proxy in an Estuarine Environment

NASA Astrophysics Data System (ADS)

George, S. E.; Herbert, T.; Amaral-Zettler, L. A.; Richter, N.

2017-12-01

Long chain polyunsaturated alkenone (LCA) lipid biomarkers produced by haptophyte phytoplankton species within the Order Isochrysidales (Phylum Haptophyta) have proven exceptionally useful in paleotemperature studies by means of the Uk'37 and Uk37 indices. Two closely-related Group III haptophytes, Emiliania huxleyi and Gephyrocapsa oceanica are the primary alkenone synthesizers in the modern ocean, while freshwater systems host the distinct Group I phylotype, sometimes called the Greenland phylotype, in reference to the location of its original discovery. Group I haptophytes produce large quantities of the distinct C37:4 ketone, which acts as a chemical `fingerprint' in sediments. The utility of alkenones as a paleotemperature proxy in estuarine environments has remained largely untested, representing an under-utilized opportunity to construct high-resolution paleotemperature records from environments at the intersection of fluvial and marine systems. This uncertainty is due, in part, to the presence of multiple haptophyte groups in estuaries, resulting in a mixed alkenone signature. To determine the community composition of alkenone-producing haptophytes within Narragansett Bay, four geographically separated cores from within the Bay were analyzed for alkenones as well as haptophyte rRNA biomarker gene presence. Haptophyte rRNA genes (small and large subunit) were recovered from surface and near-subsurface samples, and in conjunction with alkenone profiles, reveal recent haptophyte community structure and alkenone production regimes throughout the Bay. A surprising result is the recovery of rRNA biomarker genes with a 100% match to the open-ocean alkenone producer E. huxleyi in locations away from large fresh water inputs to the Bay. Results of these analyses elucidate the effect of salinity and nutrient dynamics on alkenone-producing haptophyte communities and enhance applicability of long chain polyunsaturated alkenones as lipid biomarkers in estuarine environments. Future work will enhance Uk'37 analyses of Narragansett Bay sediments to better resolve historically and climatically significant events in the region, such as European settlement, the Industrial Revolution, and 20th century warming and eutrophication.

Solid Lipid Nanoparticles and Nanostructured Lipid Carriers: Structure, Preparation and Application

PubMed Central

Naseri, Neda; Valizadeh, Hadi; Zakeri-Milani, Parvin

2015-01-01

Lipid nanoparticles (LNPs) have attracted special interest during last few decades. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) are two major types of Lipid-based nanoparticles. SLNs were developed to overcome the limitations of other colloidal carriers, such as emulsions, liposomes and polymeric nanoparticles because they have advantages like good release profile and targeted drug delivery with excellent physical stability. In the next generation of the lipid nanoparticle, NLCs are modified SLNs which improve the stability and capacity loading. Three structural models of NLCs have been proposed. These LNPs have potential applications in drug delivery field, research, cosmetics, clinical medicine, etc. This article focuses on features, structure and innovation of LNPs and presents a wide discussion about preparation methods, advantages, disadvantages and applications of LNPs by focusing on SLNs and NLCs. PMID:26504751

[Lipid synthesis by an acidic acid tolerant Rhodotorula glutinis].

PubMed

Lin, Zhangnan; Liu, Hongjuan; Zhang, Jian'an; Wang, Gehua

2016-03-01

Acetic acid, as a main by-product generated in the pretreatment process of lignocellulose hydrolysis, significantly affects cell growth and lipid synthesis of oleaginous microorganisms. Therefore, we studied the tolerance of Rhodotorula glutinis to acetic acid and its lipid synthesis from substrate containing acetic acid. In the mixed sugar medium containing 6 g/L glucose and 44 g/L xylose, and supplemented with acetic acid, the cell growth was not:inhibited when the acetic acid concentration was below 10 g/L. Compared with the control, the biomass, lipid concentration and lipid content of R. glutinis increased 21.5%, 171% and 122% respectively when acetic acid concentration was 10 g/L. Furthermore, R. glutinis could accumulate lipid with acetate as the sole carbon source. Lipid concentration and lipid yield reached 3.20 g/L and 13% respectively with the initial acetic acid concentration of 25 g/L. The lipid composition was analyzed by gas chromatograph. The main composition of lipid produced with acetic acid was palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid, including 40.9% saturated fatty acids and 59.1% unsaturated fatty acids. The lipid composition was similar to that of plant oil, indicating that lipid from oleaginous yeast R. glutinis had potential as the feedstock of biodiesel production. These results demonstrated that a certain concentration of acetic acid need not to be removed in the detoxification process when using lignocelluloses hydrolysate to produce microbial lipid by R. glutinis.

Immunopharmacology of lipid A mimetics.

PubMed

Bowen, William S; Gandhapudi, Siva K; Kolb, Joseph P; Mitchell, Thomas C

2013-01-01

The structural core of bacterial lipopolysaccharide, lipid A, has played a role in medicine since the 1890s when William Coley sought to harness its immunostimulatory properties in the form of a crude bacterial extract. Recent decades have brought remarkable clarity to the structure of lipid A and the multicomponent endotoxin receptor system that evolved to detect it. A range of therapeutically useful versions of lipid A now exists, including preparations of detoxified lipid A, synthetic copies of naturally occurring biological intermediates such as lipid IVa, and synthetic mimetics. These agents are finding use as vaccine adjuvants, antagonists and immunostimulants whose structural features have been refined to potentiate efficacy while decreasing the risk of inflammatory side effects. Copyright © 2013 Elsevier Inc. All rights reserved.

Cationic lipids: molecular structure/ transfection activity relationships and interactions with biomembranes.

PubMed

Koynova, Rumiana; Tenchov, Boris

2010-01-01

Abstract Synthetic cationic lipids, which form complexes (lipoplexes) with polyanionic DNA, are presently the most widely used constituents of nonviral gene carriers. A large number of cationic amphiphiles have been synthesized and tested in transfection studies. However, due to the complexity of the transfection pathway, no general schemes have emerged for correlating the cationic lipid chemistry with their transfection efficacy and the approaches for optimizing their molecular structures are still largely empirical. Here we summarize data on the relationships between transfection activity and cationic lipid molecular structure and demonstrate that the transfection activity depends in a systematic way on the lipid hydrocarbon chain structure. A number of examples, including a large series of cationic phosphatidylcholine derivatives, show that optimum transfection is displayed by lipids with chain length of approximately 14 carbon atoms and that the transfection efficiency strongly increases with increase of chain unsaturation, specifically upon replacement of saturated with monounsaturated chains.

Genome Characterization of Oleaginous Aspergillus oryzae BCC7051: A Potential Fungal-Based Platform for Lipid Production

DOE PAGES

Thammarongtham, Chinae; Nookaew, Intawat; Vorapreeda, Tayvich; ...

2017-09-01

The selected robust fungus, Aspergillus oryzae strain BCC7051 is of interest for biotechnological production of lipid-derived products due to its capability to accumulate high amount of intracellular lipids using various sugars and agro-industrial substrates. Here in this paper, we report the genome sequence of the oleaginous A. oryzae BCC7051. The obtained reads were de novo assembled into 25 scaffolds spanning of 38,550,958 bps with predicted 11,456 protein-coding genes. By synteny mapping, a large rearrangement was found in two scaffolds of A. oryzae BCC7051 as compared to the reference RIB40 strain. The genetic relationship between BCC7051 and other strains of A.more » oryzae in terms of aflatoxin production was investigated, indicating that the A. oryzae BCC7051 was categorized into group 2 nonaflatoxin-producing strain. Moreover, a comparative analysis of the structural genes focusing on the involvement in lipid metabolism among oleaginous yeast and fungi revealed the presence of multiple isoforms of metabolic enzymes responsible for fatty acid synthesis in BCC7051. The alternative routes of acetyl-CoA generation as oleaginous features and malate/citrate/pyruvate shuttle were also identified in this A. oryzae strain. The genome sequence generated in this work is a dedicated resource for expanding genome-wide study of microbial lipids at systems level, and developing the fungal-based platform for production of diversified lipids with commercial relevance.« less

Genome Characterization of Oleaginous Aspergillus oryzae BCC7051: A Potential Fungal-Based Platform for Lipid Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thammarongtham, Chinae; Nookaew, Intawat; Vorapreeda, Tayvich

The selected robust fungus, Aspergillus oryzae strain BCC7051 is of interest for biotechnological production of lipid-derived products due to its capability to accumulate high amount of intracellular lipids using various sugars and agro-industrial substrates. Here in this paper, we report the genome sequence of the oleaginous A. oryzae BCC7051. The obtained reads were de novo assembled into 25 scaffolds spanning of 38,550,958 bps with predicted 11,456 protein-coding genes. By synteny mapping, a large rearrangement was found in two scaffolds of A. oryzae BCC7051 as compared to the reference RIB40 strain. The genetic relationship between BCC7051 and other strains of A.more » oryzae in terms of aflatoxin production was investigated, indicating that the A. oryzae BCC7051 was categorized into group 2 nonaflatoxin-producing strain. Moreover, a comparative analysis of the structural genes focusing on the involvement in lipid metabolism among oleaginous yeast and fungi revealed the presence of multiple isoforms of metabolic enzymes responsible for fatty acid synthesis in BCC7051. The alternative routes of acetyl-CoA generation as oleaginous features and malate/citrate/pyruvate shuttle were also identified in this A. oryzae strain. The genome sequence generated in this work is a dedicated resource for expanding genome-wide study of microbial lipids at systems level, and developing the fungal-based platform for production of diversified lipids with commercial relevance.« less

A Complete NMR Spectral Assignment of the Lipid-free Mouse Apolipoprotein A-I (ApoAI) C-terminal Truncation Mutant, ApoAI(1-216)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yunhuang; Hoyt, David W.; Wang, Jianjun

2007-07-28

Apolipoprotein A-I (apoAI) is the major protein component of the high-density lipoprotein (HDL) that has been a hot subject of interests because of its anti-atherogenic properties. Upon lipid-binding, apoAI undergoes conformational changes from lipid-free to several different HDL-associated states (1). These different conformational states regulate HDL formation, maturation and transportation. Recent crystal structure of lipid-free human apoAI represents a major progress of structural study of lipid-free apoAI (2). However, no structural is available for lipid-free mouse apoAI (240-residues). Since mouse HDL is homogenous with only HDL2-like size, whereas human HDL is heterogeneous, containing HDL2/HDL3 as its main species, a structuralmore » comparison between human and mouse apoAI may allow us to identify structure basis of HDL size distribution difference between human and mouse. We carried out an NMR structure determination of lipid-free mouse apoAI (1-216) and completely assigned backbone atoms (except backbone amide proton and nitrogen atoms for residues D1, N48, W107, K108, K132, E135, F147, R148, M169 and K203). Secondary structure prediction using backbone NMR parameters indicates that lipid-free mouse apoAI consists of a four helical segments in the N-terminal domain, residues 1-180. In addition, two short helices are also observed between residues 190-195 and 210-215. The helix locations are significantly different from those in the crystal structure of human apoAI, suggesting that mouse apoAI may have a different conformational adaptation upon lipid-binding. BMRB deposit with accession number: 15091.« less

Growth of locally isolated microalga in POME to produce lipid as alternative energy sources

NASA Astrophysics Data System (ADS)

Elvitriana; Munir, E.; Delvian; Wahyuningsih, H.

2018-04-01

Purpose of this study was to find the best growth of locally isolated microalgae that produce lipids from Palm Oil Mill Effluent (POME) as an alternative energy source. Microalgae was cultivated in POME in glass vessel at room temperature using a lighting intensity of 13,000 lux and continuously aeration for 24 and 12 hours, respectively. Biomass of microalgae were analyzed daily to get their growth by spectrophotometry at 624 nm wavelength, whereas Modified Bligh and Dyer method determined lipid content. Results show that the best growth occurred at 10% inoculum with lighting cycle and aeration of 24 hours (on/off) and resulting highest biomass content of 0.99 g dry weight/L followed by the decrease of organic substances in POME. The percentage reduction of COD, BOD, TSS, and oil at POME reached above 92%, while phosphate concentration reached 89.2%. Cultivation of microalgae in POME for 12 days showed its ability to reduce organic substances and nutrients in POME and produced biomass with lipid content of 35%. These results reached to the conclusion that locally isolated microalgae has an ability to treat POME safely for environment and POME can be used as a growing medium of microalgae that produces lipids.

Method of fabricating lipid bilayer membranes on solid supports

NASA Technical Reports Server (NTRS)

Cho, Nam-Joon (Inventor); Frank, Curtis W. (Inventor); Glenn, Jeffrey S. (Inventor); Cheong, Kwang Ho (Inventor)

2012-01-01

The present invention provides a method of producing a planar lipid bilayer on a solid support. With this method, a solution of lipid vesicles is first deposited on the solid support. Next, the lipid vesicles are destabilized by adding an amphipathic peptide solution to the lipid vesicle solution. This destabilization leads to production of a planar lipid bilayer on the solid support. The present invention also provides a supported planar lipid bilayer, where the planar lipid bilayer is made of naturally occurring lipids and the solid support is made of unmodified gold or titanium oxide. Preferably, the supported planar lipid bilayer is continuous. The planar lipid bilayer may be made of any naturally occurring lipid or mixture of lipids, including, but not limited to phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinsitol, cardiolipin, cholesterol, and sphingomyelin.

Chemical and structural investigation of lipid nanoparticles: drug-lipid interaction and molecular distribution

NASA Astrophysics Data System (ADS)

Anantachaisilp, Suranan; Meejoo Smith, Siwaporn; Treetong, Alongkot; Pratontep, Sirapat; Puttipipatkhachorn, Satit; Rungsardthong Ruktanonchai, Uracha

2010-03-01

Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of γ-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812® as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the γ-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance (1H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the 1H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of γ-oryzanol inside the lipid nanoparticles, the 1H-NMR revealed that the chemical shifts of the liquid lipid in γ-oryzanol loaded systems were found at rather higher field than those in γ-oryzanol free systems, suggesting incorporation of γ-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of γ-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of γ-oryzanol and lipids (solid and liquid) inside the lipid nanoparticle systems are proposed.

Effects of an equol-producing bacterium isolated from human faeces on isoflavone and lignan metabolism in mice.

PubMed

Tamura, Motoi; Hori, Sachiko; Nakagawa, Hiroyuki; Yamauchi, Satoshi; Sugahara, Takuya

2016-07-01

Equol is a metabolite of daidzein that is produced by intestinal microbiota. The oestrogenic activity of equol is stronger than daidzein. Equol-producing bacteria are believed to play an important role in the gut. The rod-shaped and Gram-positive anaerobic equol-producing intestinal bacterium Slackia TM-30 was isolated from healthy human faeces and its effects on urinary phyto-oestrogen, plasma and faecal lipids were assessed in adult mice. The urinary amounts of equol in urine were significantly higher in mice receiving the equol-producing bacterium TM-30 (BAC) group than in the control (CO) group (P < 0.05). However, no significant differences were observed between the urinary amounts of daidzein, dihydrodaidzein, enterodiol, and enterolactone between the BAC and CO groups. No significant differences in the plasma lipids were observed between the two groups. The lipid content (% dry weight) in the faeces sampled on the final day of the experiment tended to be higher in the BAC group than in the CO group (P = 0.07). Administration of equol-producing bacterium TM-30 affected the urinary amounts of phyto-oestrogens and the faecal lipid contents of mice. The equol-producing bacterium TM-30 likely influences the metabolism of phyto-oestrogen via changes in the gastrointestinal environment. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Biotechnological conversion of waste cooking olive oil into lipid-rich biomass using Aspergillus and Penicillium strains.

PubMed

Papanikolaou, S; Dimou, A; Fakas, S; Diamantopoulou, P; Philippoussis, A; Galiotou-Panayotou, M; Aggelis, G

2011-05-01

In this study, we have investigated the biochemical behaviour of Aspergillus sp. (five strains) and Penicillium expansum (one strain) fungi cultivated on waste cooking olive oil. The production of lipid-rich biomass was the main target of the work. In parallel, the biosynthesis of other extracellular metabolites (organic acids) and enzyme (lipase) and the substrate fatty acid specificity of the strains were studied. Carbon-limited cultures were performed on waste oil, added in the growth medium at 15g l(-1) , and high biomass quantities were produced (up to c.18g l(-1) , conversion yield of c. 1·0 g of dry biomass formed per g of fat consumed or higher). Cellular lipids were accumulated in notable quantities in almost all cultures. Aspergillus sp. ATHUM 3482 accumulated lipid up to 64·0% (w/w) in dry fungal mass. In parallel, extracellular lipase activity was quantified, and it was revealed to be strain and fermentation time dependent, with a maximum quantity of 645 U ml(-1) being obtained by Aspergillus niger NRRL 363. Storage lipid content significantly decreased at the stationary growth phase. Some differences in the fatty acid composition of both cellular and residual lipids when compared with the initial substrate fat used were observed; in various cases, cellular lipids more saturated and enriched with arachidic acid were produced. Aspergillus strains produced oxalic acid up to 5·0 g l(-1) . Aspergillus and Penicillium strains are able to convert waste cooking olive oil into high-added-value products.   Increasing fatty wastes amounts are annually produced. The current study provided an alternative way of biovalourization of these materials, by using them as substrates, to produce added-value compounds. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

Microorganism Utilization for Synthetic Milk

NASA Technical Reports Server (NTRS)

Morford, Megan A.; Khodadad, Christina L.; Caro, Janicce I.; Spencer, LaShelle E.; Richards, Jeffery T.; Strayer, Richard F.; Birmele, Michele N.; Wheeler, Raymond M.

2014-01-01

A desired architecture for long duration spaceflight, like aboard the International Space Station or for future missions to Mars, is to provide a supply of fresh food crops for the astronauts. However, some crops can create a high proportion of inedible plant waste. The main goal of the Synthetic Biology project, Cow in a Column, was to produce the components of milk (sugar, lipid, protein) from inedible plant waste by utilizing microorganisms (fungi, yeast, bacteria). Of particular interest was utilizing the valuable polysaccharide, cellulose, found in plant waste, to naturally fuel-through microorganism cellular metabolism- the creation of sugar (glucose), lipid (milk fat), and protein (casein) in order to produce a synthetic edible food product. Environmental conditions such as pH, temperature, carbon source, aeration, and choice microorganisms were optimized in the laboratory and the desired end-products, sugars and lipids, were analyzed. Trichoderma reesei, a known cellulolytic fungus, was utilized to drive the production of glucose, with the intent that the produced glucose would serve as the carbon source for milk fat production and be a substitute for the milk sugar lactose. Lipid production would be carried out by Rhodosporidium toruloides, yeast known to accumulate those lipids that are typically found in milk fat. Results showed that glucose and total lipid content were below what was expected during this phase of experimentation. In addition, individual analysis of six fatty acids revealed that the percentage of each fatty acid was lower than naturally produced bovine milk. Overall, this research indicates that microorganisms could be utilized to breakdown inedible solid waste to produce useable products. For future work, the production of the casein protein for milk would require the development of a genetically modified organism, which was beyond the scope of the original project. Additional trials would be needed to further refine the required environment/organisms for the production of desired sugar and lipid end-products.

Carbonyl-Phenol Adducts: An Alternative Sink for Reactive and Potentially Toxic Lipid Oxidation Products.

PubMed

Zamora, Rosario; Hidalgo, Francisco J

2018-02-14

Different from the well-characterized function of phenolics as antioxidants, their function as lipid-derived carbonyl scavengers is mostly unknown. However, phenolics react with lipid-derived carbonyls as a function of the nucleophilicity of their reactive groups and the electronic effects and steric hindrances present in the reactive carbonyls. Furthermore, the reaction produces a wide variety of carbonyl-phenol adducts, some of which are stable and have been isolated and characterized but others polymerize spontaneously. This perspective updates present knowledge about the lipid-derived carbonyl trapping ability of phenolics, its competition with carbonyl-amine reactions produced in foods, and the presence of carbonyl-phenol adducts in food products.

Archaeosomes: an excellent carrier for drug and cell delivery.

PubMed

Kaur, Gurmeet; Garg, Tarun; Rath, Goutam; Goyal, Amit K

2016-09-01

Archaeosomes as liposomes made with one or more ether lipids that are unique to the domain of Archaeobacteria, found in Archaea constitute a novel family of liposome. Achaean-type lipids consist of archaeol (diether) and/or caldarchaeol (tetraether) core structures. Archaeosomes can be produced using standard procedures (hydrated film submitted to sonication, extrusion and detergent dialysis) at any temperature in the physiological range or lower, therefore making it possible to encapsulate thermally stable compounds. Various physiological as well as environmental factors affect its stability. Archaeosomes are widely used as drug delivery systems for cancer vaccines, Chagas disease, proteins and peptides, gene delivery, antigen delivery and delivery of natural antioxidant compounds. In this review article, our major aim was to explore the applications of this new carrier system in pharmaceutical field.

Structural changes in plastids of developing Splachnum ampullaceum sporophytes and relationship to odour production

PubMed Central

McCuaig, B.; Dufour, S. C.; Raguso, R. A.; Bhatt, A. P.; Marino, P.

2014-01-01

Many mosses of the family Splachnaceae are entomophilous and rely on flies for spore dispersal. Splachnum ampullaceum produces a yellow- or pink-coloured hypophysis that releases volatile compounds, attracting flies to the mature moss. The biosynthetic sources of the visual and aromatic cues within the hypophysis have not been identified, and may be either symbiotic cyanobacteria or chromoplasts that break down lipids into volatile compounds. Here, we used transmission electron microscopy and gas chromatography-mass spectrometry (GC-MS) to investigate the sources of these attractants, focusing on different tissues and stages of maturation. Microscopy revealed an abundance of plastids within the hypophysis, while no symbiotic bacteria were observed. During plant maturation, plastids differentiated from amyloplasts with large starch granules to photosynthetic chloroplasts and finally to chromoplasts with lipid accumulations. We used GC-MS to identify over 50 volatile organic compounds from mature sporophytes including short-chain oxygenated compounds, unsaturated irregular terpenoids, fatty acid-derived 6- and 8-carbon alcohols and ketones, and the aromatic compounds acetophenone and p-cresol. The hypophysis showed localised production of pungent volatiles, mainly short-chain fermentation compounds and p-cresol. Some of these volatiles have been shown to be produced from lipid oxidase degradation of linolenic acid within chromoplasts. However, other compounds (such as cyclohexanecarboxylic acid esters) may have a microbial origin. Further investigation is necessary to identify the origin of fly attractants in these mosses. PMID:25213550

Keratins and lipids in ethnic hair.

PubMed

Cruz, C F; Fernandes, M M; Gomes, A C; Coderch, L; Martí, M; Méndez, S; Gales, L; Azoia, N G; Shimanovich, U; Cavaco-Paulo, A

2013-06-01

Human hair has an important and undeniable relevance in society due to its important role in visual appearance and social communication. Hair is mainly composed of structural proteins, mainly keratin and keratin associated proteins and lipids. Herein, we report a comprehensive study of the content and distribution of the lipids among ethnic hair, African, Asian and Caucasian hair. More interestingly, we also report the study of the interaction between those two main components of hair, specifically, the influence of the hair internal lipids in the structure of the hair keratin. This was achieved by the use of a complete set of analytical tools, such as thin layer chromatography-flame ionization detector, X-ray analysis, molecular dynamics simulation and confocal microscopy. The experimental results indicated different amounts of lipids on ethnic hair compositions and higher percentage of hair internal lipids in African hair. In this type of hair, the axial diffraction of keratin was not observed in X-ray analysis, but after hair lipids removal, the keratin returned to its typical packing arrangement. In molecular dynamic simulation, lipids were shown to intercalate dimers of keratin, changing its structure. From those results, we assume that keratin structure may be influenced by higher concentration of lipids in African hair. © 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Analysis of membrane fusion as a two-state sequential process: evaluation of the stalk model.

PubMed

Weinreb, Gabriel; Lentz, Barry R

2007-06-01

We propose a model that accounts for the time courses of PEG-induced fusion of membrane vesicles of varying lipid compositions and sizes. The model assumes that fusion proceeds from an initial, aggregated vesicle state ((A) membrane contact) through two sequential intermediate states (I(1) and I(2)) and then on to a fusion pore state (FP). Using this model, we interpreted data on the fusion of seven different vesicle systems. We found that the initial aggregated state involved no lipid or content mixing but did produce leakage. The final state (FP) was not leaky. Lipid mixing normally dominated the first intermediate state (I(1)), but content mixing signal was also observed in this state for most systems. The second intermediate state (I(2)) exhibited both lipid and content mixing signals and leakage, and was sometimes the only leaky state. In some systems, the first and second intermediates were indistinguishable and converted directly to the FP state. Having also tested a parallel, two-intermediate model subject to different assumptions about the nature of the intermediates, we conclude that a sequential, two-intermediate model is the simplest model sufficient to describe PEG-mediated fusion in all vesicle systems studied. We conclude as well that a fusion intermediate "state" should not be thought of as a fixed structure (e.g., "stalk" or "transmembrane contact") of uniform properties. Rather, a fusion "state" describes an ensemble of similar structures that can have different mechanical properties. Thus, a "state" can have varying probabilities of having a given functional property such as content mixing, lipid mixing, or leakage. Our data show that the content mixing signal may occur through two processes, one correlated and one not correlated with leakage. Finally, we consider the implications of our results in terms of the "modified stalk" hypothesis for the mechanism of lipid pore formation. We conclude that our results not only support this hypothesis but also provide a means of analyzing fusion time courses so as to test it and gauge the mechanism of action of fusion proteins in the context of the lipidic hypothesis of fusion.

Interaction of cholesterol-conjugated ionizable amino lipids with biomembranes: lipid polymorphism, structure-activity relationship, and implications for siRNA delivery.

PubMed

Zhang, Jingtao; Fan, Haihong; Levorse, Dorothy A; Crocker, Louis S

2011-08-02

Delivery of siRNA is a major obstacle to the advancement of RNAi as a novel therapeutic modality. Lipid nanoparticles (LNP) consisting of ionizable amino lipids are being developed as an important delivery platform for siRNAs, and significant efforts are being made to understand the structure-activity relationship (SAR) of the lipids. This article uses a combination of small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) to evaluate the interaction between cholesterol-conjugated ionizable amino lipids and biomembranes, focusing on an important area of lipid SAR--the ability of lipids to destabilize membrane bilayer structures and facilitate endosomal escape. In this study, cholesterol-conjugated amino lipids were found to be effective in increasing the order of biomembranes and also highly effective in inducing phase changes in biological membranes in vitro (i.e., the lamellar to inverted hexagonal phase transition). The phase transition temperatures, determined using SAXS and DSC, serve as an indicator for ranking the potency of lipids to destabilize endosomal membranes. It was found that the bilayer disruption ability of amino lipids depends strongly on the amino lipid concentration in membranes. Amino lipids with systematic variations in headgroups, the extent of ionization, tail length, the degree of unsaturation, and tail asymmetry were evaluated for their bilayer disruption ability to establish SAR. Overall, it was found that the impact of these lipid structure changes on their bilayer disruption ability agrees well with the results from a conceptual molecular "shape" analysis. Implications of the findings from this study for siRNA delivery are discussed. The methods reported here can be used to support the SAR screening of cationic lipids for siRNA delivery, and the information revealed through the study of the interaction between cationic lipids and biomembranes will contribute significantly to the design of more efficient siRNA delivery vehicles.

Isomer distribution of hydroxyoctadecadienoates (HODE) and hydroxyeicosatetraenoates (HETE) produced in the plasma oxidation mediated by peroxyl radical, peroxynitrite, hypochlorite, 15-lipoxygenase, and singlet oxygen.

PubMed

Umeno, Aya; Morita, Mayuko; Yoshida, Yasukazu; Naito, Yuji; Niki, Etsuo

2017-12-01

Free and ester forms of unsaturated fatty acids and cholesterol are oxidized in vivo by multiple oxidants to give diverse products. Some lipid oxidation is mediated by enzymes to selectively give specific products, while others proceed randomly to produce mixtures of many kinds of regioisomers and stereoisomers. The efficacy of antioxidants against lipid oxidation depends on the nature of the oxidants and therefore the identification of oxidant is important for understanding the roles and effects of lipid oxidation and antioxidants in vivo. In the present study, the isomer distribution of hydro(pero)xyoctadecadienoates (H(p)ODEs) and hydro(pero)xyeicosatetraenoates (H(p)ETEs), the most abundant lipid oxidation products found in human plasma, produced in the oxidation of plasma by peroxyl radicals, peroxynitrite, hypochlorite, 15-lipoxygenase, and singlet oxygen were examined. It was shown that 9- and 13-(E,E)-HODEs, 13(S)-(Z,E)-HODE, and 10- and 12-(Z,E)-HODEs were specific lipid oxidation products by free radical, 15-lipoxygenase, and singlet oxygen, respectively. The isomer distribution of HODEs produced by peroxynitrite was similar to that by peroxyl radical, suggesting that the peroxynitrite mediated lipid oxidation proceeds by free radical mechanisms. The production of HODEs and HETEs by hypochlorite was very small. HODEs may be a better biomarker than HETEs since linoleates are oxidized by simpler mechanisms than arachidonates and all the HODEs isomers can be quantified more easily. These products may be used as specific biomarkers for the identification of responsible oxidants and for the assessment of oxidant-specific lipid oxidation levels and effects of antioxidants in vivo. Copyright © 2017 Elsevier Inc. All rights reserved.

Low-cost production of green microalga Botryococcus braunii biomass with high lipid content through mixotrophic and photoautotrophic cultivation.

PubMed

Yeesang, Chittra; Cheirsilp, Benjamas

2014-09-01

Botryococcus braunii is a microalga that is regarded as a potential source of renewable fuel because of its ability to produce large amounts of lipid that can be converted into biodiesel. Agro-industrial by-products and wastes are of great interest as cultivation medium for microorganisms because of their low cost, renewable nature, and abundance. In this study, two strategies for low-cost production of B. braunii biomass with high lipid content were performed: (i) the mixotrophic cultivation using molasses, a cheap by-product from the sugar cane plant as a carbon source, and (ii) the photoautotrophic cultivation using nitrate-rich wastewater supplemented with CO2 as a carbon source. The mixotrophic cultivation added with 15 g L(-1) molasses produced a high amount of biomass of 3.05 g L(-1) with a high lipid content of 36.9 %. The photoautotrophic cultivation in nitrate-rich wastewater supplemented with 2.0 % CO2 produced a biomass of 2.26 g L(-1) and a lipid content of 30.3 %. The benefits of this photoautotrophic cultivation are that this cultivation would help to reduce accumulation of atmospheric carbon dioxide and more than 90 % of the nitrate could be removed from the wastewater. When this cultivation was scaled up in a stirred tank photobioreactor and run with semi-continuous cultivation regime, the highest microalgal biomass of 5.16 g L(-1) with a comparable lipid content of 32.2 % was achieved. These two strategies could be promising ways for producing cheap lipid-rich microalgal biomass that can be used as biofuel feedstocks and animal feeds.

Effects of temperature on growth and lipid synthesis of diatom Chaetoceros Curvisetus and the Northern Adriatic (Mediteranean) plankton community

NASA Astrophysics Data System (ADS)

Novak, Tihana; Gašparović, Blaženka; Godrijan, Jelena; Maric, Daniela; Djakovac, Tamara; Mlakar, Marina

2017-04-01

Phytoplankton is the major primary producer in the world. Marine phytoplankton lives in a rather changing environment, with variations in temperature, light, salinity, nutrient availability, etc. In such changing environment phytoplankton should live, grow and reproduce, and, in order to achieve that, they fix carbon and nutrients to produce biomolecules (lipids, proteins and carbohydrates). Lipids are a good indicator of organic matter (OM) processes in the seas and oceans, also good bioindicators for OM origin, and phytoplankton adaptations to environmental stress. Marine lipids are produced by organisms, mostly in phototrophic part of the seas and oceans, and their crucial producer is phytoplankton. We were interested to see how the increasing temperature and different nutrient availability affect quantitative and qualitative lipid and lipid classes production by plankton community. To test how marine phytoplankton would respond to predicted increasing temperature we conducted monoculture batch experiments in laboratory on model diatom Chaetoceros curvisetus at five different temperatures from 10 to 30C. Also we conducted experiments in phosphorous replete and deplete conditions mimicking eutrophic and oligotrophic marine conditions. We have chosen Chaetoceros curvisetus as a model culture since it is a major component of Northern Adriatic (NA) phytoplankton, but also Chaetoceros genus of diatoms is most abundant in wide range of marine ecosystems. We also conducted annual sampling of the NA particulate matter that covers the same temperature range as for the batch experiments. NA samples were taken on two stations with different nutrient supply that were characterized as oligotrophic and mesotrophic stations. Samples were taken from 2013 to 2014 on a monthly basis. Lipid classes were characterized with thin-layer chromatography-flame ionization detection. Data are supported by particulate organic carbon (POC), chlorophyll a (Chl a) concentrations and phytoplankton taxonomy and cell abundances.

NMR spectroscopy for assessing lipid oxidation

USDA-ARS?s Scientific Manuscript database

Although lipid oxidation involves a variety of chemical reactions to produce numerous substances, most of traditional methods assessing lipid oxidation measure only one kind of oxidation product. For this reason, in general, one indicator of oxidation is not enough to accurately describe the oxidati...

Molecular dynamics simulations of glyphosate in a DPPC lipid bilayer.

PubMed

Frigini, Ezequiel N; López Cascales, J J; Porasso, Rodolfo D

2018-07-01

Extensive molecular dynamics simulations have been performed to study the effect of glyphosate (in their neutral and charged forms, GLYP and GLYP 2- , respectively) on fully hydrated DiPalmitoylPhosphatidylCholine (DPPC) lipid bilayer. First, we calculated the free energy profile (using the Umbrella Sampling technique) for both states of charge of glyphosate. The minimum value for the free energy for GLYP is ∼-60 kJ mol -1 located at z = ±1.7 nm (from the lipid bilayer center), and there is almost no maximum at the center of the lipid bilayer. By contrast, the minimum for GLYP 2- is ∼-35 kJ mol -1 located at z = ± 1.4 nm (from the lipid bilayer center), and the maximum reaches ∼35 kJ mol -1 at the center of the lipid bilayer. Then, different lipid bilayer properties were analyzed for different glyphosate:lipid (G:L) ratios. The mean area per lipid was slightly affected, increasing only 5% (in the presence of glyphosate at high concentrations), which is in agreement with the slight decrease in deuterium order parameters. As for the thickness of the bilayer, it is observed that the state of charge produces opposite effects. On one hand, the neutral state produces an increase in the thickness of the lipid bilayer; on the other, the charged form produces a decrease in the thickness, which not depend linearly on the G:L ratios, either. The orientation of the DPPC head groups is practically unaffected throughout the range of the G:L ratios studied. Finally, the mobility of the lipids of the bilayer is strongly affected by the presence of glyphosate, considerably increasing its lateral diffusion coefficient noteworthy (one order of magnitude), with increasing G:L ratio. Copyright © 2018 Elsevier B.V. All rights reserved.

Contributions of the N- and C-terminal helical segments to the lipid-free structure and lipid interaction of apolipoprotein A-I.

PubMed

Tanaka, Masafumi; Dhanasekaran, Padmaja; Nguyen, David; Ohta, Shinya; Lund-Katz, Sissel; Phillips, Michael C; Saito, Hiroyuki

2006-08-29

The tertiary structure of lipid-free apolipoprotein (apo) A-I in the monomeric state comprises two domains: a N-terminal alpha-helix bundle and a less organized C-terminal domain. This study examined how the N- and C-terminal segments of apoA-I (residues 1-43 and 223-243), which contain the most hydrophobic regions in the molecule and are located in opposite structural domains, contribute to the lipid-free conformation and lipid interaction. Measurements of circular dichroism in conjunction with tryptophan and 8-anilino-1-naphthalenesulfonic acid fluorescence data demonstrated that single (L230P) or triple (L230P/L233P/Y236P) proline insertions into the C-terminal alpha helix disrupted the organization of the C-terminal domain without affecting the stability of the N-terminal helix bundle. In contrast, proline insertion into the N terminus (Y18P) disrupted the bundle structure in the N-terminal domain, indicating that the alpha-helical segment in this region is part of the helix bundle. Calorimetric and gel-filtration measurements showed that disruption of the C-terminal alpha helix significantly reduced the enthalpy and free energy of binding of apoA-I to lipids, whereas disruption of the N-terminal alpha helix had only a small effect on lipid binding. Significantly, the presence of the Y18P mutation offset the negative effects of disruption/removal of the C-terminal helical domain on lipid binding, suggesting that the alpha helix around Y18 concealed a potential lipid-binding region in the N-terminal domain, which was exposed by the disruption of the helix-bundle structure. When these results are taken together, they indicate that the alpha-helical segment in the N terminus of apoA-I modulates the lipid-free structure and lipid interaction in concert with the C-terminal domain.

Template-based combinatorial enumeration of virtual compound libraries for lipids

PubMed Central

2012-01-01

A variety of software packages are available for the combinatorial enumeration of virtual libraries for small molecules, starting from specifications of core scaffolds with attachments points and lists of R-groups as SMILES or SD files. Although SD files include atomic coordinates for core scaffolds and R-groups, it is not possible to control 2-dimensional (2D) layout of the enumerated structures generated for virtual compound libraries because different packages generate different 2D representations for the same structure. We have developed a software package called LipidMapsTools for the template-based combinatorial enumeration of virtual compound libraries for lipids. Virtual libraries are enumerated for the specified lipid abbreviations using matching lists of pre-defined templates and chain abbreviations, instead of core scaffolds and lists of R-groups provided by the user. 2D structures of the enumerated lipids are drawn in a specific and consistent fashion adhering to the framework for representing lipid structures proposed by the LIPID MAPS consortium. LipidMapsTools is lightweight, relatively fast and contains no external dependencies. It is an open source package and freely available under the terms of the modified BSD license. PMID:23006594

Template-based combinatorial enumeration of virtual compound libraries for lipids.

PubMed

Sud, Manish; Fahy, Eoin; Subramaniam, Shankar

2012-09-25

A variety of software packages are available for the combinatorial enumeration of virtual libraries for small molecules, starting from specifications of core scaffolds with attachments points and lists of R-groups as SMILES or SD files. Although SD files include atomic coordinates for core scaffolds and R-groups, it is not possible to control 2-dimensional (2D) layout of the enumerated structures generated for virtual compound libraries because different packages generate different 2D representations for the same structure. We have developed a software package called LipidMapsTools for the template-based combinatorial enumeration of virtual compound libraries for lipids. Virtual libraries are enumerated for the specified lipid abbreviations using matching lists of pre-defined templates and chain abbreviations, instead of core scaffolds and lists of R-groups provided by the user. 2D structures of the enumerated lipids are drawn in a specific and consistent fashion adhering to the framework for representing lipid structures proposed by the LIPID MAPS consortium. LipidMapsTools is lightweight, relatively fast and contains no external dependencies. It is an open source package and freely available under the terms of the modified BSD license.

Lipid structure does not modify incorporation of EPA and DHA into blood lipids in healthy adults: a randomised-controlled trial.

PubMed

West, Annette L; Burdge, Graham C; Calder, Philip C

2016-09-01

Dietary supplementation is an effective means to improve EPA and DHA status. However, it is unclear whether lipid structure affects EPA+DHA bioavailability. We determined the effect of consuming different EPA and DHA lipid structures on their concentrations in blood during the postprandial period and during dietary supplementation compared with unmodified fish oil TAG (uTAG). In a postprandial cross-over study, healthy men (n 9) consumed in random order test meals containing 1·1 g EPA+0·37 g DHA as either uTAG, re-esterified TAG, free fatty acids (FFA) or ethyl esters (EE). In a parallel design supplementation study, healthy men and women (n 10/sex per supplement) consumed one supplement type for 12 weeks. Fatty acid composition was determined by GC. EPA incorporation over 6 h into TAG or phosphatidylcholine (PC) did not differ between lipid structures. EPA enrichment in NEFA was lower from EE than from uTAG (P=0·01). Plasma TAG, PC or NEFA DHA incorporation did not differ between lipid structures. Lipid structure did not affect TAG or NEFA EPA incorporation and PC or NEFA DHA incorporation following dietary supplementation. Plasma TAG peak DHA incorporation was greater (P=0·02) and time to peak shorter (P=0·02) from FFA than from uTAG in men. In both studies, the order of EPA and DHA incorporation was PC>TAG>NEFA. In conclusion, EPA and DHA lipid structure may not be an important consideration in dietary interventions.

Molecular dynamics study of structure and vibrational spectra at zwitterionoic lipid/aqueous KCl, NaCl, and CaCl2 solution interfaces

NASA Astrophysics Data System (ADS)

Ishiyama, Tatsuya; Shirai, Shinnosuke; Okumura, Tomoaki; Morita, Akihiro

2018-06-01

Molecular dynamics (MD) simulations of KCl, NaCl, and CaCl2 solution/dipalmytoylphosphatidylcholine lipid interfaces were performed to analyze heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectra in relation to the interfacial water structure. The present MD simulation well reproduces the experimental spectra and elucidates a specific cation effect on the interfacial structure. The K+, Na+, and Ca2+ cation species penetrate in the lipid layer more than the anions in this order, due to the electrostatic interaction with negative polar groups of lipid, and the electric double layer between the cations and anions cancels the intrinsic orientation of water at the water/lipid interface. These mechanisms explain the HD-VSFG spectrum of the water/lipid interface and its spectral perturbation by adding the ions. The lipid monolayer reverses the order of surface preference of the cations at the solution/lipid interface from that at the solution/air interface.

Polyunsaturated Fatty Acids in Lipid Bilayers and Tubules

NASA Astrophysics Data System (ADS)

Hirst, Linda S.; Yuan, Jing; Pramudya, Yohannes; Nguyen, Lam T.

2007-03-01

Omega-3 polyunsaturated fatty acids (PUFAs) are found in a variety of biological membranes and have been implicated with lipid raft formation and possible function, typical molecules include DHA (Docosahexanoic Acid) and AA (Alphalinoleic Acid) which have been the focus of considerable attention in recent years. We are interested in the phase behavior of these molecules in the lipid bilayer. The addition of lipid molecules with polyunsaturated chains has a clear effect on the fluidity and curvature of the membrane and we investigate the effects the addition of polyunsaturated lipids on bilayer structure and tubule formation. Self-assembled cylindrical lipid tubules have attracted considerable attention because of their interesting structures and potential technological applications. Using x-ray diffraction techniques, Atomic Force Microscopy and confocal fluorescence imaging, both symmetric and mixed chain lipids were incorporated into model membranes and the effects on bilayer structure and tubule formation investigated.

Cationic niosomes an effective gene carrier composed of novel spermine-derivative cationic lipids: effect of central core structures.

PubMed

Opanasopit, Praneet; Leksantikul, Lalita; Niyomtham, Nattisa; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Yingyongnarongkul, Boon-Ek

2017-05-01

Cationic niosomes formulated from Span 20, cholesterol (Chol) and novel spermine-based cationic lipids of multiple central core structures (di(oxyethyl)amino, di(oxyethyl)amino carboxy, 3-amino-1,2-dioxypropyl and 2-amino-1,3-dioxypropyl) were successfully prepared for improving transfection efficiency in vitro. The niosomes composed of spermine cationic lipid with central core structure of di(oxyethyl)amino revealed the highest gene transfection efficiency. To investigate the factors affecting gene transfection and cell viability including differences in the central core structures of cationic lipids, the composition of vesicles, molar ratio of cationic lipids in formulations and the weight ratio of niosomes to DNA. Cationic niosomes composed of nonionic surfactants (Span20), cholesterol and spermine-based cationic lipids of multiple central core structures were formulated. Gene transfection and cell viability were evaluated on a human cervical carcinoma cell line (HeLa cells) using pDNA encoding green fluorescent protein (pEGFP-C2). The morphology, size and charge were also characterized. High transfection efficiency was obtained from cationic niosomes composed of Span20:Chol:cationic lipid at the molar ratio of 2.5:2.5:0.5 mM. Cationic lipids with di(oxyethyl)amino as a central core structure exhibited highest transfection efficiency. In addition, there was also no serum effect on transfection efficiency. These novel cationic niosomes may constitute a good alternative carrier for gene transfection.

Dynamics of lipid and fatty acid composition of shallow-water corals under thermal stress: an experimental approach

NASA Astrophysics Data System (ADS)

Imbs, A. B.; Yakovleva, I. M.

2012-03-01

Coral bleaching induces changes in lipid and fatty acid composition that result in low lipid content, reducing the likelihood of coral survival. Species-specific differences in the metabolism of lipid reserves may contribute to the differential resistance of corals under acute heat exposures. Here, we examined the dynamics of lipids and fatty acid abundance in corals subjected to short-term heat stress. The stony corals Acropora intermedia, Montipora digitata, and the soft coral Sinularia capitalis all showed a 60-75% decline in both storage and structural lipids. However, S. capitalis and M. digitata exhibited no significant change in the percentages of structural lipids (i.e., polar lipids and sterols) until they had lost 90-95% of their endosymbionts, whereas A. intermedia showed a rapid decline in structural lipids after a 50% loss of symbionts. After a 90-95% loss of symbionts under heat stress, all three corals showed a relative depletion of polyunsaturated fatty acids that had symbiont biomarkers, suggesting that polyunsaturated fatty acids were translocated from the symbiont to the coral host tissue.

Analysis of lipid experiments (ALEX): a software framework for analysis of high-resolution shotgun lipidomics data.

PubMed

Husen, Peter; Tarasov, Kirill; Katafiasz, Maciej; Sokol, Elena; Vogt, Johannes; Baumgart, Jan; Nitsch, Robert; Ekroos, Kim; Ejsing, Christer S

2013-01-01

Global lipidomics analysis across large sample sizes produces high-content datasets that require dedicated software tools supporting lipid identification and quantification, efficient data management and lipidome visualization. Here we present a novel software-based platform for streamlined data processing, management and visualization of shotgun lipidomics data acquired using high-resolution Orbitrap mass spectrometry. The platform features the ALEX framework designed for automated identification and export of lipid species intensity directly from proprietary mass spectral data files, and an auxiliary workflow using database exploration tools for integration of sample information, computation of lipid abundance and lipidome visualization. A key feature of the platform is the organization of lipidomics data in "database table format" which provides the user with an unsurpassed flexibility for rapid lipidome navigation using selected features within the dataset. To demonstrate the efficacy of the platform, we present a comparative neurolipidomics study of cerebellum, hippocampus and somatosensory barrel cortex (S1BF) from wild-type and knockout mice devoid of the putative lipid phosphate phosphatase PRG-1 (plasticity related gene-1). The presented framework is generic, extendable to processing and integration of other lipidomic data structures, can be interfaced with post-processing protocols supporting statistical testing and multivariate analysis, and can serve as an avenue for disseminating lipidomics data within the scientific community. The ALEX software is available at www.msLipidomics.info.

Engineering Rhodosporidium toruloides for increased lipid production.

PubMed

Zhang, Shuyan; Skerker, Jeffrey M; Rutter, Charles D; Maurer, Matthew J; Arkin, Adam P; Rao, Christopher V

2016-05-01

Oleaginous yeast are promising organisms for the production of lipid-based chemicals and fuels from simple sugars. In this work, we explored Rhodosporidium toruloides for the production of lipid-based products. This oleaginous yeast natively produces lipids at high titers and can grow on glucose and xylose. As a first step, we sequenced the genomes of two strains, IFO0880, and IFO0559, and generated draft assemblies and annotations. We then used this information to engineer two R. toruloides strains for increased lipid production by over-expressing the native acetyl-CoA carboxylase and diacylglycerol acyltransferase genes using Agrobacterium tumefaciens mediated transformation. Our best strain, derived from IFO0880, was able to produce 16.4 ± 1.1 g/L lipid from 70 g/L glucose and 9.5 ± 1.3 g/L lipid from 70 g/L xylose in shake-flask experiments. This work represents one of the first examples of metabolic engineering in R. toruloides and establishes this yeast as a new platform for production of fatty-acid derived products. © 2015 Wiley Periodicals, Inc.

Highly stable lipid-encapsulation of fluorescent nanodiamonds for bioimaging applications.

PubMed

Sotoma, Shingo; Hsieh, Feng-Jen; Chen, Yen-Wei; Tsai, Pei-Chang; Chang, Huan-Cheng

2018-01-23

Highly stable lipid-encapsulated fluorescent nanodiamonds (FNDs) are produced by photo-crosslinking of diacetylene-containing lipids physically attached to the FND surface. Not only is this coating method simple and fast, but also it gives the FND-lipid hybrids favorable properties for bioapplications. The hybrids are useful as fluorescent biolabels as well as fiducial markers for correlative light and electron microscopy.

Effect of head group orientation on phospholipid assembly

NASA Astrophysics Data System (ADS)

Paul, Tanay; Saha, Jayashree

2017-06-01

The relationship between bilayer stability and lipid head group orientation is reported. In this work, molecular-dynamics simulations are performed to analyze the structure-property relationship of lipid biomembranes, taking into account coarse-grained model lipid interactions. The work explains the molecular scale mechanism of the phase behavior of lipid systems due to ion-lipid or anesthetic-lipid interactions, where reorientations of dipoles play a key role in modifying lipid phases and thereby alter biomembrane function. Our study demonstrates that simple dipolar reorientation is indeed sufficient in tuning a bilayer to a randomly flipped nonbilayer lamellar phase. This study may be used to assess the impact of changes in lipid phase characteristics on biomembrane structure due to the presence of anesthetics and ions.

Structure of Carbon Nanotube Porins in Lipid Bilayers: An in Situ Small-Angle X-ray Scattering (SAXS) Study [Atomic-level structure of carbon nanotube porins in lipid bilayers: an in-situ small-angle x-ray scattering (SAXS) study

DOE PAGES

Tran, Ich C.; Tunuguntla, Ramya H.; Kim, Kyunghoon; ...

2016-06-20

Carbon nanotube porins (CNTPs), small segments of carbon nanotubes capable of forming defined pores in lipid membranes, are important future components for bionanoelectronic devices as they could provide a robust analog of biological membrane channels. Furthermore, in order to control the incorporation of these CNT channels into lipid bilayers, it is important to understand the structure of the CNTPs before and after insertion into the lipid bilayer as well as the impact of such insertion on the bilayer structure. Here we employed a noninvasive in situ probe, small-angle X-ray scattering, to study the integration of CNT porins into dioleoylphosphatidylcholine bilayers.more » These results show that CNTPs in solution are stabilized by a monolayer of lipid molecules wrapped around their outer surface. We also demonstrate that insertion of CNTPs into the lipid bilayer results in decreased bilayer thickness with the magnitude of this effect increasing with the concentration of CNTPs.« less

Membrane Lipid Oscillation: An Emerging System of Molecular Dynamics in the Plant Membrane.

PubMed

Nakamura, Yuki

2018-03-01

Biological rhythm represents a major biological process of living organisms. However, rhythmic oscillation of membrane lipid content is poorly described in plants. The development of lipidomic technology has led to the illustration of precise molecular profiles of membrane lipids under various growth conditions. Compared with conventional lipid signaling, which produces unpredictable lipid changes in response to ever-changing environmental conditions, lipid oscillation generates a fairly predictable lipid profile, adding a new layer of biological function to the membrane system and possible cross-talk with the other chronobiological processes. This mini review covers recent studies elucidating membrane lipid oscillation in plants.

Research advancements in palm oil nutrition.

PubMed

May, Choo Yuen; Nesaretnam, Kalanithi

2014-10-01

Palm oil is the major oil produced, with annual world production in excess of 50 million tonnes. About 85% of global palm oil produced is used in food applications. Over the past three decades, research on nutritional benefits of palm oil have demonstrated the nutritional adequacy of palm oil and its products, and have resulted in transitions in the understanding these attributes. Numerous studies have demonstrated that palm oil was similar to unsaturated oils with regards to effects on blood lipids. Palm oil provides a healthy alternative to trans-fatty acid containing hydrogenated fats that have been demonstrated to have serious deleterious effects on health. The similar effects of palm oil on blood lipids, comparable to other vegetable oils could very well be due to the structure of the major triglycerides in palm oil, which has an unsaturated fatty acid in the stereospecific numbers ( sn) -2 position of the glycerol backbone. In addition, palm oil is well endowed with a bouquet of phytonutrients beneficial to health, such as tocotrienols, carotenoids, and phytosterols. This review will provide an overview of studies that have established palm oil as a balanced and nutritious oil.

Research advancements in palm oil nutrition*

PubMed Central

May, Choo Yuen; Nesaretnam, Kalanithi

2014-01-01

Palm oil is the major oil produced, with annual world production in excess of 50 million tonnes. About 85% of global palm oil produced is used in food applications. Over the past three decades, research on nutritional benefits of palm oil have demonstrated the nutritional adequacy of palm oil and its products, and have resulted in transitions in the understanding these attributes. Numerous studies have demonstrated that palm oil was similar to unsaturated oils with regards to effects on blood lipids. Palm oil provides a healthy alternative to trans-fatty acid containing hydrogenated fats that have been demonstrated to have serious deleterious effects on health. The similar effects of palm oil on blood lipids, comparable to other vegetable oils could very well be due to the structure of the major triglycerides in palm oil, which has an unsaturated fatty acid in the stereospecific numbers (sn)-2 position of the glycerol backbone. In addition, palm oil is well endowed with a bouquet of phytonutrients beneficial to health, such as tocotrienols, carotenoids, and phytosterols. This review will provide an overview of studies that have established palm oil as a balanced and nutritious oil. PMID:25821404

Characterization of Oilseed Lipids from “DHA-Producing Camelina sativa”: A New Transformed Land Plant Containing Long-Chain Omega-3 Oils

PubMed Central

Mansour, Maged P.; Shrestha, Pushkar; Belide, Srinivas; Petrie, James R.; Nichols, Peter D.; Singh, Surinder P.

2014-01-01

New and sustainable sources of long-chain (LC, ≥C20) omega-3 oils containing DHA (docosahexaenoic acid, 22:6ω3) are required to meet increasing demands. The lipid content of the oilseed of a novel transgenic, DHA-producing land plant, Camelina sativa, containing microalgal genes able to produce LC omega-3 oils, contained 36% lipid by weight with triacylglycerols (TAG) as the major lipid class in hexane extracts (96% of total lipid). Subsequent chloroform-methanol (CM) extraction recovered further lipid (~50% polar lipid, comprising glycolipids and phospholipids) and residual TAG. The main phospholipid species were phosphatidyl choline and phosphatidyl ethanolamine. The % DHA was: 6.8% (of total fatty acids) in the TAG-rich hexane extract and 4.2% in the polar lipid-rich CM extract. The relative level of ALA (α-linolenic acid, 18:3ω3) in DHA-camelina seed was higher than the control. Major sterols in both DHA- and control camelina seeds were: sitosterol, campesterol, cholesterol, brassicasterol and isofucosterol. C16–C22 fatty alcohols, including iso-branched and odd-chain alcohols were present, including high levels of iso-17:0, 17:0 and 19:0. Other alcohols present were: 16:0, iso-18:0, 18:0 and 18:1 and the proportions varied between the hexane and CM extracts. These iso-branched odd-chain fatty alcohols, to our knowledge, have not been previously reported. These components may be derived from wax esters, or free fatty alcohols. PMID:24566436

Biomass and oil production by Chlorella vulgaris and four other microalgae - Effects of salinity and other factors.

PubMed

Luangpipat, Tiyaporn; Chisti, Yusuf

2017-09-10

Five nominally freshwater microalgae (Chlorella vulgaris, Choricystis minor, Neochloris sp., Pseudococcomyxa simplex, Scenedesmus sp.) with a known ability to produce high-levels of lipids for possible use as fuel oils were evaluated for their ability to thrive and produce lipids in seawater and brackish water. Only C. vulgaris was found to thrive and produce lipids in full strength seawater. Seawater tolerant strains of C. vulgaris are unusual. Lipid productivity in nutrient sufficient seawater exceeded 37mgL -1 d -1 and was nearly 2-fold greater than in freshwater. Although other microalgae such as C. minor had higher lipid productivities (e.g. 45mgL -1 d -1 ), they did not thrive in seawater. The lipid content of the C. vulgaris biomass was nearly 16% by dry weight. The calorific value of the seawater-grown C. vulgaris biomass exceeded 25kJg -1 . Compared to continuously illuminated cultures, a 12/12h light-dark cycle reduced lipid productivity of C. vulgaris by ∼30%, but did not affect the lipid content of the biomass. Biomass yield on phosphate was nearly 27% higher in seawater compared to in freshwater. While C. vulgaris has been extensively studied in freshwater, it has not been examined to any detail in full strength seawater. Studies in seawater are essential for any future large scale production of algal oils for biofuels: seawater is available cheaply and in large amounts whereas there is a global shortage of freshwater. Copyright © 2016 Elsevier B.V. All rights reserved.

Quorum sensing molecules in activated sludge could trigger microalgae lipid synthesis.

PubMed

Zhang, Chaofan; Li, Qingcheng; Fu, Liang; Zhou, Dandan; Crittenden, John C

2018-05-18

Cultivating microalgae using wastewater is an economical strategy to produce biofuel; however, microbial contamination has to be controlled strictly. Microalgae lipid accumulation can be triggered by environmental pressures, and here, we studied whether microbial contamination is the pressure for microalgae. We hypothesized this pressure was forced via cell-to-cell communication with quorum sensing molecules (QSMs). In this work, we verified the impacts of QSMs produced by activated sludge (wastewater-born microbial consortiums) on both lipid content and biomass production of the microalgae Chlorophyta sp., since in combination, they determined lipid productivity. With QSMs stress, the lipid content of Chlorophyta sp. increased by ∼84%, while biomass production decreased only slightly. Consistently, enzymes on the fatty acid synthesis pathways were generally up-regulated, while they were slightly down-regulated for DNA replication. In summary, the total lipid production improved by 86%. These results revealed the positive effects of microbial contamination on microalgae biofuel production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comprehensive metabolomic, lipidomic and microscopic profiling of Yarrowia lipolytica during lipid accumulation identifies targets for increased lipogenesis

DOE PAGES

Pomraning, Kyle R.; Wei, Siwei; Karagiosis, Sue A.; ...

2015-04-23

Yarrowia lipolytica is an oleaginous ascomycete yeast that accumulates large amounts of lipids and has potential as a biofuel producing organism. Despite a growing scientific literature focused on lipid production by Y. lipolytica, there remain significant knowledge gaps regarding the key biological processes involved. We applied a combination of metabolomic and lipidomic profiling approaches as well as microscopic techniques to identify and characterize the key pathways involved in de novo lipid accumulation from glucose in batch cultured, wild-type Y. lipolytica. We found that lipids accumulated rapidly and peaked at 48 hours during the five day experiment, concurrent with a shiftmore » in amino acid metabolism. We also report that Y. lipolytica secretes disaccharides early in batch culture and reabsorbs them when extracellular glucose is depleted. Exhaustion of extracellular sugars coincided with thickening of the cell wall, suggesting that genes involved in cell wall biogenesis may be a useful target for improving the efficiency of lipid producing yeast strains.« less

Lipid and fatty acid analysis of the Plodia interpunctella granulosis virus (PiGV) envelope

NASA Technical Reports Server (NTRS)

Shastri-Bhalla, K.; Funk, C. J.; Consigli, R. A.; Spooner, B. S. (Principal Investigator)

1993-01-01

Virus envelope was isolated from Plodia interpunctella granulosis virus, produced in early fourth-instar larvae. Both polar and neutral lipids were analyzed by two-dimensional thin-layer chromatography. Fatty acid composition of various individual neutral and polar lipids was determined by gas-liquid chromatography. The major components of envelope neutral lipid were diacylglycerols. Palmitic acid and stearic acid were the major saturated fatty acids in both polar and neutral lipids. Whereas palmitoleic acid was the major unsaturated fatty acids in neutral lipids, oleic acid was the major unsaturated fatty acid in the polar lipids.

The Structure of the Mouse Serotonin 5-HT3 Receptor in Lipid Vesicles.

PubMed

Kudryashev, Mikhail; Castaño-Díez, Daniel; Deluz, Cédric; Hassaine, Gherici; Grasso, Luigino; Graf-Meyer, Alexandra; Vogel, Horst; Stahlberg, Henning

2016-01-05

The function of membrane proteins is best understood if their structure in the lipid membrane is known. Here, we determined the structure of the mouse serotonin 5-HT3 receptor inserted in lipid bilayers to a resolution of 12 Å without stabilizing antibodies by cryo electron tomography and subtomogram averaging. The reconstruction reveals protein secondary structure elements in the transmembrane region, the extracellular pore, and the transmembrane channel pathway, showing an overall similarity to the available X-ray model of the truncated 5-HT3 receptor determined in the presence of a stabilizing nanobody. Structural analysis of the 5-HT3 receptor embedded in a lipid bilayer allowed the position of the membrane to be determined. Interactions between the densely packed receptors in lipids were visualized, revealing that the interactions were maintained by the short horizontal helices. In combination with methodological improvements, our approach enables the structural analysis of membrane proteins in response to voltage and ligand gating. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structural proteomics: Topology and relative accessibility of plant lipid droplet associated proteins.

PubMed

Jolivet, Pascale; Aymé, Laure; Giuliani, Alexandre; Wien, Frank; Chardot, Thierry; Gohon, Yann

2017-10-03

Lipid droplets are the major stock of lipids in oleaginous plant seeds. Despite their economic importance for oil production and biotechnological issues (biofuels, lubricants and plasticizers), numerous questions about their formation, structure and regulation are still unresolved. To determine water accessible domains of protein coating at lipid droplets surface, a structural proteomic approach has been performed. This technique relies on the millisecond timescale production of hydroxyl radicals by the radiolysis of water using Synchrotron X-ray white beam. Thanks to the evolution of mass spectrometry analysis techniques this approach allows the creation of a map of the solvent accessibility for proteins difficult to study by other means. Using these results, a S3 oleosin water accessibility map is proposed. This is the first time that such a map on an oleosin co-purified with plant lipid droplets and other associated protein is presented. Lipid droplet associated proteins function is linked to stability, structure and probably formation and lipid mobilization of droplets. Structure of these proteins in their native environment, at the interface between bulk water and the lipidic core of these organelles is only based on hydrophobicity plot. Using hydroxyl radical footprinting and proteomics approaches we studied water accessibility of one major protein in these droplets: S3 oleosin of Arabidopsis thaliana seeds. Copyright © 2017 Elsevier B.V. All rights reserved.

Cardiolipins Act as a Selective Barrier to Toll-Like Receptor 4 Activation in the Intestine

PubMed Central

Coats, Stephen R.; Hashim, Ahmed; Paramonov, Nikolay A.; Curtis, Michael A.

2016-01-01

ABSTRACT Intestinal homeostasis mechanisms must protect the host intestinal tissue from endogenous lipopolysaccharides (LPSs) produced by the intestinal microbiota. In this report, we demonstrate that murine intestinal fecal lipids effectively block Toll-like receptor 4 (TLR4) responses to naturally occurring Bacteroidetes sp. LPS. Cardiolipin (CL) represents a significant proportion of the total intestinal and fecal lipids and, furthermore, potently antagonizes TLR4 activation by reducing LPS binding at the lipopolysaccharide binding protein (LBP), CD14, and MD-2 steps of the TLR4 signaling pathway. It is further demonstrated that intestinal lipids and CL are less effective at neutralizing more potent Enterobacteriaceae-type LPS, which is enriched in feces obtained from mice with dextran sodium sulfate (DSS)-treated inflammatory bowel disease. The selective inhibition of naturally occurring LPS structures by intestinal lipids may represent a novel homeostasis mechanism that blocks LPS activation in response to symbiotic but not dysbiotic microbial communities. IMPORTANCE The guts of animals harbor a variety of Gram-negative bacteria associated with both states of intestinal health and states of disease. Environmental factors, such as dietary habits, can drive the microbial composition of the host animal's intestinal bacterial community toward a more pathogenic state. Both beneficial and harmful Gram-negative bacteria are capable of eliciting potentially damaging inflammatory responses from the host intestinal tissues via a lipopolysaccharide (LPS)-dependent pathway. Physical mucosal barriers and antibodies produced by the intestinal immune system protect against the undesired inflammatory effects of LPS, although it is unknown why some bacteria are more effective at overcoming the protective barriers than others. This report describes the discovery of a lipid-type protective barrier in the intestine that reduces the deleterious effects of LPSs from beneficial bacteria but is less effective in dampening the inflammatory effects of LPSs from harmful bacteria, providing a novel mechanistic insight into inflammatory intestinal disorders. PMID:27208127

Membrane insertion for the detection of lipopolysaccharides: Exploring the dynamics of amphiphile-in-lipid assays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stromberg, Loreen R.; Hengartner, Nicolas W.; Swingle, Kirstie L.

Shiga toxin-producing Escherichia coli is an important cause of foodborne illness, with cases attributable to beef, fresh produce and other sources. Many serotypes of the pathogen cause disease, and differentiating one serotype from another requires specific identification of the O antigen located on the lipopolysaccharide (LPS) molecule. The amphiphilic structure of LPS poses a challenge when using classical detection methods, which do not take into account its lipoglycan biochemistry. Typically, detection of LPS requires heat or chemical treatment of samples and relies on bioactivity assays for the conserved lipid A portion of the molecule. Our goal was to develop assaysmore » to facilitate the direct and discriminative detection of the entire LPS molecule and its O antigen in complex matrices using minimal sample processing. To perform serogroup identification of LPS, we used a method called membrane insertion on a waveguide biosensor, and tested three serogroups of LPS. The membrane insertion technique allows for the hydrophobic association of LPS with a lipid bilayer, where the exposed O antigen can be targeted for specific detection. Samples of beef lysate were spiked with LPS to perform O antigen specific detection of LPS from E. coli O157. To validate assay performance, we evaluated the biophysical interactions of LPS with lipid bilayers both in- and outside of a flow cell using fluorescence microscopy and fluorescently doped lipids. Our results indicate that membrane insertion allows for the qualitative and reliable identification of amphiphilic LPS in complex samples like beef homogenates. In addition, we also demonstrated that LPS-induced hole formation does not occur under the conditions of the membrane insertion assays. Together, these findings describe for the first time the serogroup-specific detection of amphiphilic LPS in complex samples using a membrane insertion assay, and highlight the importance of LPS molecular conformations in detection architectures.« less

Membrane insertion for the detection of lipopolysaccharides: Exploring the dynamics of amphiphile-in-lipid assays

DOE PAGES

Stromberg, Loreen R.; Hengartner, Nicolas W.; Swingle, Kirstie L.; ...

2016-05-26

Shiga toxin-producing Escherichia coli is an important cause of foodborne illness, with cases attributable to beef, fresh produce and other sources. Many serotypes of the pathogen cause disease, and differentiating one serotype from another requires specific identification of the O antigen located on the lipopolysaccharide (LPS) molecule. The amphiphilic structure of LPS poses a challenge when using classical detection methods, which do not take into account its lipoglycan biochemistry. Typically, detection of LPS requires heat or chemical treatment of samples and relies on bioactivity assays for the conserved lipid A portion of the molecule. Our goal was to develop assaysmore » to facilitate the direct and discriminative detection of the entire LPS molecule and its O antigen in complex matrices using minimal sample processing. To perform serogroup identification of LPS, we used a method called membrane insertion on a waveguide biosensor, and tested three serogroups of LPS. The membrane insertion technique allows for the hydrophobic association of LPS with a lipid bilayer, where the exposed O antigen can be targeted for specific detection. Samples of beef lysate were spiked with LPS to perform O antigen specific detection of LPS from E. coli O157. To validate assay performance, we evaluated the biophysical interactions of LPS with lipid bilayers both in- and outside of a flow cell using fluorescence microscopy and fluorescently doped lipids. Our results indicate that membrane insertion allows for the qualitative and reliable identification of amphiphilic LPS in complex samples like beef homogenates. In addition, we also demonstrated that LPS-induced hole formation does not occur under the conditions of the membrane insertion assays. Together, these findings describe for the first time the serogroup-specific detection of amphiphilic LPS in complex samples using a membrane insertion assay, and highlight the importance of LPS molecular conformations in detection architectures.« less

Investigation of antioxidant systems in human meibomian gland and conjunctival tissues.

PubMed

Nezzar, Hachemi; Mbekeani, Joyce N; Noblanc, Anais; Chiambaretta, Frédéric; Drevet, Joël R; Kocer, Ayhan

2017-12-01

Oxidative stress (OS) associated with direct contact with the environment and light exposure is a very potent and continuous stressor of the ocular surface and internal structures of the eye that are required to manage its effects. Constant replenishment of tears together with the superficial lipid layer produced by the meibomian glands (MG) is one protective mechanism. The lipid-rich fraction of the tears coats the deeper aqueous fraction, preventing its evaporation. However, lipids are particularly sensitive to oxidative damage that could alter tear film quality. To counteract oxidative damage, MG along with other structures of the ocular surface use primary antioxidant (AO) systems to limit OS damage such as lipid peroxidation. Limited information concerning the primary enzymatic AO system of the human MG prompted this investigation. Using different approaches (RT-PCR, enzymatic activity assays and immuno-fluorescent microscopy), we determined the presence, distribution and subcellular locations of the major AO enzymes belonging to the classical catalytic triad (superoxide dismutase, catalase and glutathione peroxidases) in adult human MG and conjunctiva (Conj). We showed that both tissues exhibit glutathione peroxidase expression. In addition to the ubiquitous cytosolic GPx1 protein, there was significant expression of GPx2, GPx4 and GPx7. These isoforms are known to preferentially scavenge phospholipid-hydroperoxide compounds. This characterization of the primary AO system of human MG and Conj may help pave the way for the development of diagnostic procedures and have implications for treatment of common MG dysfunction (MGD) and dry eye syndrome (DES). Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis, characterization, and evaluation of ionizable lysine-based lipids for siRNA delivery.

PubMed

Walsh, Colin L; Nguyen, Juliane; Tiffany, Matthew R; Szoka, Francis C

2013-01-16

We report the synthesis and characterization of a series of ionizable lysine-based lipids (ILL), novel lipids containing a lysine headgroup linked to a long-chain dialkylamine through an amide linkage at the lysine α-amine. These ILLs contain two ionizable amines and a carboxylate, and exhibit pH-dependent lipid ionization that varies with lipid structure. The synthetic scheme employed allows for the simple, orthogonal manipulation of lipids. This provides a method for the development of a compositionally diverse library with varying ionizable headgroups, tail structures, and linker regions. A focused library of four ILLs was synthesized to determine the impact of hydrophobic fluidity, lipid net charge, and lipid pK(a) on the biophysical and siRNA transfection characteristics of this new class of lipids. We found that manipulation of lipid structure impacts the protonation behavior, electrostatically driven membrane disruption, and ability to promote siRNA mediated knockdown in vitro. ILL-siRNA liposomal formulations were tested in a murine Factor VII model; however, no significant siRNA-mediated knockdown was observed. These results indicate that ILL may be useful in vitro transfection reagents, but further optimization of this new class of lipids is required to develop an effective in vivo siRNA delivery system.

New lipid family that forms inverted cubic phases in equilibrium with excess water: molecular structure-aqueous phase structure relationship for lipids with 5,9,13,17-tetramethyloctadecyl and 5,9,13,17-tetramethyloctadecanoyl chains.

PubMed

Yamashita, Jun; Shiono, Manzo; Hato, Masakatsu

2008-10-02

With a view to discovering a new family of lipids that form inverted cubic phases, the aqueous phase behavior of a series of lipids with isoprenoid-type hydrophobic chains has been examined over a temperature range from -40 to 65 degrees C by using optical microscopy, DSC (differential scanning calorimetry), and SAXS (small-angle X-ray scattering) techniques. The lipids examined are those with 5,9,13,17-tetramethyloctadecyl and 5,9,13,17-tetramethyloctadecanoyl chains linked to a series of headgroups, that is, erythritol, pentaerythritol, xylose, and glucose. All of the lipid/water systems displayed a "water + liquid crystalline phase" two-phase coexistence state when sufficiently diluted. The aqueous phase structures of the most diluted liquid crystalline phases in equilibrium with excess water depend both on the lipid molecular structure and on the temperature. Given an isoprenoid chain, the preferred phase consistently follows a phase sequence of an H II (an inverted hexagonal phase) to a Q II (an inverted bicontinuous cubic phase) to an L alpha (a lamellar phase) as A* (cross-section area of the headgroup) increases. For a given lipid/water system, the phase sequence observed as the temperature increases is L alpha to Q II to H II. The present study allowed us to find four cubic phase-forming lipid species, PEOC 18+4 [mono- O-(5,9,13,17-tetramethyloctadecyl)pentaerythritol], beta-XylOC 18+4 [1- O-(5,9,13,17-tetramethyloctadecyl)-beta- d-xylopyranoside], EROCOC 17+4 [1- O-(5,9,13,17-tetramethyloctadecanoyl)erythritol], and PEOCOC 17+4 [mono- O-(5,9,13,17-tetramethyloctadecanoyl)pentaerythritol]. The values of T K (hydrated solid-liquid crystalline phase transition temperature) of the cubic phase-forming lipids are all below 0 degrees C. Quantitative analyses of the lipid molecular structure-aqueous phase structure relationship in terms of the experimentally evaluated "surfactant parameter" allow us to rationally select an optimum combination of hydrophilic/hydrophobic part of a lipid molecule that will form a desired phase in a desired temperature range.

Synthesis and Characterization of a Novel Phenolic Lipid for Use as Potential Lipophilic Antioxidant and as a Prodrug of Butyric Acid.

PubMed

Kaki, Shiva Shanker; Kunduru, Konda Reddy; Kanjilal, Sanjit; Narayana Prasad, Rachapudi Badari

2015-01-01

Ferulic acid was modified to produce a novel phenolipid containing butyl chains. Ferulic acid was esterified with butanol to produce butyl ferulate which was further dihydroxylated followed by esterification with butyric anhydride to produce the phenolipid containing butyric acid. IR, NMR and MS techniques confirmed the structure of the synthesized structured lipophilic phenolic compound. The synthesized compound was tested for in vitro antioxidant and antimicrobial activities. The produced phenolipid showed moderate antioxidant activity in DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging assay but in linoleic acid oxidation method, it exhibited good activity compared with the parent compound and the reference compounds. The prepared derivative could find applications as antioxidant in lipophilic systems and also as a potential prodrug of butyric acid. It also showed antibacterial effect against the four bacterial strains studied. The drug-likeness properties of the prepared molecule calculated were in the acceptable ranges according to Lipinski's rule of 5 and suggest that it has potential to cross the blood-brain barrier.

Automated Lipid A Structure Assignment from Hierarchical Tandem Mass Spectrometry Data

NASA Astrophysics Data System (ADS)

Ting, Ying S.; Shaffer, Scott A.; Jones, Jace W.; Ng, Wailap V.; Ernst, Robert K.; Goodlett, David R.

2011-05-01

Infusion-based electrospray ionization (ESI) coupled to multiple-stage tandem mass spectrometry (MS n ) is a standard methodology for investigating lipid A structural diversity (Shaffer et al. J. Am. Soc. Mass. Spectrom. 18(6), 1080-1092, 2007). Annotation of these MS n spectra, however, has remained a manual, expert-driven process. In order to keep up with the data acquisition rates of modern instruments, we devised a computational method to annotate lipid A MS n spectra rapidly and automatically, which we refer to as hierarchical tandem mass spectrometry (HiTMS) algorithm. As a first-pass tool, HiTMS aids expert interpretation of lipid A MS n data by providing the analyst with a set of candidate structures that may then be confirmed or rejected. HiTMS deciphers the signature ions (e.g., A-, Y-, and Z-type ions) and neutral losses of MS n spectra using a species-specific library based on general prior structural knowledge of the given lipid A species under investigation. Candidates are selected by calculating the correlation between theoretical and acquired MS n spectra. At a false discovery rate of less than 0.01, HiTMS correctly assigned 85% of the structures in a library of 133 manually annotated Francisella tularensis subspecies novicida lipid A structures. Additionally, HiTMS correctly assigned 85% of the structures in a smaller library of lipid A species from Yersinia pestis demonstrating that it may be used across species.

Machine-Learned Data Structures of Lipid Marker Serum Concentrations in Multiple Sclerosis Patients Differ from Those in Healthy Subjects.

PubMed

Lötsch, Jörn; Thrun, Michael; Lerch, Florian; Brunkhorst, Robert; Schiffmann, Susanne; Thomas, Dominique; Tegder, Irmgard; Geisslinger, Gerd; Ultsch, Alfred

2017-06-07

Lipid metabolism has been suggested to be a major pathophysiological mechanism of multiple sclerosis (MS). With the increasing knowledge about lipid signaling, acquired data become increasingly complex making bioinformatics necessary in lipid research. We used unsupervised machine-learning to analyze lipid marker serum concentrations, pursuing the hypothesis that for the most relevant markers the emerging data structures will coincide with the diagnosis of MS. Machine learning was implemented as emergent self-organizing feature maps (ESOM) combined with the U*-matrix visualization technique. The data space consisted of serum concentrations of three main classes of lipid markers comprising eicosanoids ( d = 11 markers), ceramides ( d = 10), and lyosophosphatidic acids ( d = 6). They were analyzed in cohorts of MS patients ( n = 102) and healthy subjects ( n = 301). Clear data structures in the high-dimensional data space were observed in eicosanoid and ceramides serum concentrations whereas no clear structure could be found in lysophosphatidic acid concentrations. With ceramide concentrations, the structures that had emerged from unsupervised machine-learning almost completely overlapped with the known grouping of MS patients versus healthy subjects. This was only partly provided by eicosanoid serum concentrations. Thus, unsupervised machine-learning identified distinct data structures of bioactive lipid serum concentrations. These structures could be superimposed with the known grouping of MS patients versus healthy subjects, which was almost completely possible with ceramides. Therefore, based on the present analysis, ceramides are first-line candidates for further exploration as drug-gable targets or biomarkers in MS.

Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy as an Analytical Method to Investigate the Secondary Structure of a Model Protein Embedded in Solid Lipid Matrices.

PubMed

Zeeshan, Farrukh; Tabbassum, Misbah; Jorgensen, Lene; Medlicott, Natalie J

2018-02-01

Protein drugs may encounter conformational perturbations during the formulation processing of lipid-based solid dosage forms. In aqueous protein solutions, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy can investigate these conformational changes following the subtraction of spectral interference of solvent with protein amide I bands. However, in solid dosage forms, the possible spectral contribution of lipid carriers to protein amide I band may be an obstacle to determine conformational alterations. The objective of this study was to develop an ATR FT-IR spectroscopic method for the analysis of protein secondary structure embedded in solid lipid matrices. Bovine serum albumin (BSA) was chosen as a model protein, while Precirol AT05 (glycerol palmitostearate, melting point 58 ℃) was employed as the model lipid matrix. Bovine serum albumin was incorporated into lipid using physical mixing, melting and mixing, or wet granulation mixing methods. Attenuated total reflection FT-IR spectroscopy and size exclusion chromatography (SEC) were performed for the analysis of BSA secondary structure and its dissolution in aqueous media, respectively. The results showed significant interference of Precirol ATO5 with BSA amide I band which was subtracted up to 90% w/w lipid content to analyze BSA secondary structure. In addition, ATR FT-IR spectroscopy also detected thermally denatured BSA solid alone and in the presence of lipid matrix indicating its suitability for the detection of denatured protein solids in lipid matrices. Despite being in the solid state, conformational changes occurred to BSA upon incorporation into solid lipid matrices. However, the extent of these conformational alterations was found to be dependent on the mixing method employed as indicated by area overlap calculations. For instance, the melting and mixing method imparted negligible effect on BSA secondary structure, whereas the wet granulation mixing method promoted more changes. Size exclusion chromatography analysis depicted the complete dissolution of BSA in the aqueous media employed in the wet granulation method. In conclusion, an ATR FT-IR spectroscopic method was successfully developed to investigate BSA secondary structure in solid lipid matrices following the subtraction of lipid spectral interference. The ATR FT-IR spectroscopy could further be applied to investigate the secondary structure perturbations of therapeutic proteins during their formulation development.

Improvement in fermentation characteristics of degermed ground corn by lipid supplementation.

PubMed

Murthy, Ganti S; Singh, Vijay; Johnston, David B; Rausch, Kent D; Tumbleson, M E

2006-08-01

With rapid growth of fuel ethanol industry, and concomitant increase in distillers dried grains with solubles (DDGS), new corn fractionation technologies that reduce DDGS volume and produce higher value coproducts in dry grind ethanol process have been developed. One of the technologies, a dry degerm, defiber (3D) process (similar to conventional corn dry milling) was used to separate germ and pericarp fiber prior to the endosperm fraction fermentation. Recovery of germ and pericarp fiber in the 3D process results in removal of lipids from the fermentation medium. Biosynthesis of lipids, which is important for cell growth and viability, cannot proceed in strictly anaerobic fermentations. The effects of ten different lipid supplements on improving fermentation rates and ethanol yields were studied and compared to the conventional dry grind process. Endosperm fraction (from the 3D process) was mixed with water and liquefied by enzymatic hydrolysis and was fermented using simultaneous saccharification and fermentation. The highest ethanol concentration (13.7% v/v) was achieved with conventional dry grind process. Control treatment (endosperm fraction from 3D process without lipid supplementation) produced the lowest ethanol concentration (11.2% v/v). Three lipid treatments (fatty acid ester, alkylphenol, and ethoxylated sorbitan ester 1836) were most effective in improving final ethanol concentrations. Fatty acid ester treatment produced the highest final ethanol concentration (12.3% v/v) among all lipid supplementation treatments. Mean final ethanol concentrations of alkylphenol and ethoxylated sorbitan ester 1836 supplemented samples were 12.3 and 12.0% v/v, respectively.

Toxicity and teratogenicity studies with the hypolipidemic drug RMI 14,514 in rats.

PubMed

Gibson, J P; Larson, E J; Yarrington, J T; Hook, R H; Kariya, T; Blohm, T R

1981-01-01

The hypolipidemic drug RMI 14,514 (5-tetradecyloxy-2-furoic acid) has an oral LD50 of over 5000 mg/kg in rats. In a chronic toxicity study (6 months drug diet) doses of 30, 100, or 300 mg/kg/day produced no obvious signs of toxicity or abnormal clinical pathology parameters, other than prominent growth retardation at 300 mg/kg, which was somewhat alleviated when the dose was reduced to 200 mg/kg after 6 weeks. Hepatic change in the form of mild lipid accumulation was noted histopathologically after 6 months of treatment at 100 or 300 mg/kg/day, but was not present at 3 months or after 4 weeks off drug. The administration of RMI 14,514 in the diet to pregnant rats at 30, 100, or 150 mg/kg/day on Days 7 thru 21 of pregnancy (day 1 = day sperm detected) did not induce any teratogenic effects. When rats were exposed to the drug from implantation thru sexual maturity (126 days of age) at the same dosage, it produced no adverse developmental or behavioral effects, except for slight reduction in weight gain from birth to sexual maturity at 150 mg/kg/day. The drug caused reductions in plasma cholesterol and total fatty acids, but no distinct changes in various tissue lipids, except in the erythrocyte where fatty acids and phospholipids were reduced. These differences did not affect membrane integrity of the erythrocyte as far as osmotic or mechanical fragility tests could determine. The drug, which bears a structural resemblance to long-chain fatty acids, was incorporated into tissue lipids in detectable amounts, but tended to disappear from tissues at a rate similar to that of expected lipid turnover after treatment was stopped.

Structural characterization of the lipids A of three Bordetella bronchiseptica strains: variability of fatty acid substitution.

PubMed Central

Zarrouk, H; Karibian, D; Bodie, S; Perry, M B; Richards, J C; Caroff, M

1997-01-01

The structures of lipids A isolated from the lipopolysaccharides (LPSs; endotoxins) of three different pathogenic Bordetella bronchiseptica strains were investigated by chemical composition and methylation analysis, gas chromatography-mass spectrometry, nuclear magnetic resonance, and plasma desorption mass spectrometry (PDMS). The analyses revealed that the LPSs contain the classical lipid A bisphosphorylated beta-(1-->6)-linked D-glucosamine disaccharide with hydroxytetradecanoic acid in amide linkages. Their structures differ from that of the lipid A of Bordetella pertussis endotoxin by the replacement of hydroxydecanoic acid on the C-3 position with hydroxydodecanoic acid or dodecanoic acid and the presence of variable amounts of hexadecanoic acid. The dodecanoic acid is the first nonhydroxylated fatty acid to be found directly linked to a lipid A glucosamine. The lipids A were heterogeneous and composed of one to three major and several minor molecular species. The fatty acids in ester linkage were localized by PDMS of chemically modified lipids A. B. pertussis lipids A are usually hypoacylated with respect to those of enterobacterial lipids A. However, one of the three B. bronchiseptica strains had a major hexaacylated molecular species. C-4 and C-6' hydroxyl groups of the backbone disaccharide were unsubstituted, the latter being the proposed attachment site of the polysaccharide. The structural variability seen in these three lipids A was unusual for a single species and may have consequences for the pathogenicity of this Bordetella species. PMID:9171426

Structural characterization of the lipids A of three Bordetella bronchiseptica strains: variability of fatty acid substitution.

PubMed

Zarrouk, H; Karibian, D; Bodie, S; Perry, M B; Richards, J C; Caroff, M

1997-06-01

The structures of lipids A isolated from the lipopolysaccharides (LPSs; endotoxins) of three different pathogenic Bordetella bronchiseptica strains were investigated by chemical composition and methylation analysis, gas chromatography-mass spectrometry, nuclear magnetic resonance, and plasma desorption mass spectrometry (PDMS). The analyses revealed that the LPSs contain the classical lipid A bisphosphorylated beta-(1-->6)-linked D-glucosamine disaccharide with hydroxytetradecanoic acid in amide linkages. Their structures differ from that of the lipid A of Bordetella pertussis endotoxin by the replacement of hydroxydecanoic acid on the C-3 position with hydroxydodecanoic acid or dodecanoic acid and the presence of variable amounts of hexadecanoic acid. The dodecanoic acid is the first nonhydroxylated fatty acid to be found directly linked to a lipid A glucosamine. The lipids A were heterogeneous and composed of one to three major and several minor molecular species. The fatty acids in ester linkage were localized by PDMS of chemically modified lipids A. B. pertussis lipids A are usually hypoacylated with respect to those of enterobacterial lipids A. However, one of the three B. bronchiseptica strains had a major hexaacylated molecular species. C-4 and C-6' hydroxyl groups of the backbone disaccharide were unsubstituted, the latter being the proposed attachment site of the polysaccharide. The structural variability seen in these three lipids A was unusual for a single species and may have consequences for the pathogenicity of this Bordetella species.

How relevant are assembled equilibrium samples in understanding structure formation during lipid digestion?

PubMed

Phan, Stephanie; Salentinig, Stefan; Hawley, Adrian; Boyd, Ben J

2015-10-01

Lipid-based formulations are gaining interest for use as drug delivery systems for poorly water-soluble drug compounds. During digestion, the lipolysis products self-assemble with endogenous surfactants in the gastrointestinal tract to form colloidal structures, enabling enhanced drug solubilisation. Although earlier studies in the literature focus on assembled equilibrium systems, little is known about structure formation under dynamic lipolysis conditions. The purpose of this study was to investigate the likely colloidal structure formation in the small intestine after the ingestion of lipids, under equilibrium and dynamic conditions. The structural aspects were studied using small angle X-ray scattering and dynamic light scattering, and were found to depend on lipid composition, lipid chain length, prandial state and emulsification. Incorporation of phospholipids and lipolysis products into bile salt micelles resulted in swelling of the structure. At insufficient bile salt concentrations, a co-existing lamellar phase was observed, due to a reduction in the solubilisation capacity for lipolysis products. Emulsification accelerated the rate of lipolysis and structure formation. Copyright © 2015 Elsevier B.V. All rights reserved.

Lipid nanotechnologies for structural studies of membrane-associated proteins.

PubMed

Stoilova-McPhie, Svetla; Grushin, Kirill; Dalm, Daniela; Miller, Jaimy

2014-11-01

We present a methodology of lipid nanotubes (LNT) and nanodisks technologies optimized in our laboratory for structural studies of membrane-associated proteins at close to physiological conditions. The application of these lipid nanotechnologies for structure determination by cryo-electron microscopy (cryo-EM) is fundamental for understanding and modulating their function. The LNTs in our studies are single bilayer galactosylceramide based nanotubes of ∼20 nm inner diameter and a few microns in length, that self-assemble in aqueous solutions. The lipid nanodisks (NDs) are self-assembled discoid lipid bilayers of ∼10 nm diameter, which are stabilized in aqueous solutions by a belt of amphipathic helical scaffold proteins. By combining LNT and ND technologies, we can examine structurally how the membrane curvature and lipid composition modulates the function of the membrane-associated proteins. As proof of principle, we have engineered these lipid nanotechnologies to mimic the activated platelet's phosphtaidylserine rich membrane and have successfully assembled functional membrane-bound coagulation factor VIII in vitro for structure determination by cryo-EM. The macromolecular organization of the proteins bound to ND and LNT are further defined by fitting the known atomic structures within the calculated three-dimensional maps. The combination of LNT and ND technologies offers a means to control the design and assembly of a wide range of functional membrane-associated proteins and complexes for structural studies by cryo-EM. The presented results confirm the suitability of the developed methodology for studying the functional structure of membrane-associated proteins, such as the coagulation factors, at a close to physiological environment. © 2014 Wiley Periodicals, Inc.

Bicarbonate trigger for inducing lipid accumulation in algal systems

DOEpatents

Gardner, Robert; Peyton, Brent; Cooksey, Keith E.

2015-08-04

The present invention provides bicarbonate containing and/or bicarbonate-producing compositions and methods to induce lipid accumulation in an algae growth system, wherein the algae growth system is under light-dark cycling condition. By adding said compositions at a specific growth stage, said methods lead to much higher lipid accumulation and/or significantly reduced total time required for accumulating lipid in the algae growth system.

Membrane architectures for ion-channel switch-based electrochemical biosensors

DOEpatents

Sansinena, Jose-Maria; Redondo, Antonio; Swanson, Basil I.; Yee, Chanel Kitmon; Sapuri/Butti, Annapoorna R.; Parikh, Atul N.; Yang, Calvin

2008-10-28

The present invention is directed to a process of forming a bilayer lipid membrane structure by depositing an organic layer having a defined surface area onto an electrically conductive substrate, removing portions of said organic layer upon said electrically conductive substrate whereby selected portions of said organic layer are removed to form defined voids within said defined surface area of said organic layer and defined islands of organic layer upon said electrically conductive substrate, and, depositing a bilayer lipid membrane over the defined voids and defined islands of organic layer upon said substrate whereby aqueous reservoirs are formed between said electrically conductive substrate and said bilayer lipid membrane, said bilayer lipid membrane characterized as spanning across the defined voids between said defined islands. A lipid membrane structure is also described together with an array of such lipid membrane structure.

Simple, effective protein extraction method and proteomics analysis from polyunsaturated fatty acids-producing micro-organisms.

PubMed

Ling, Xueping; Guo, Jing; Zheng, Chuqiang; Ye, Chiming; Lu, Yinghua; Pan, Xueshan; Chen, Zhengqi; Ng, I-Son

2015-12-01

Polyunsaturated fatty acids (PUFAs) are valuable ingredients in the food and pharmaceutical products due to their beneficial influence on human health. Most studies paid attention on the production of PUFAs from oleaginous micro-organisms but seldom on the comparative proteomics of cells. In the study, three methods (i.e., cold shock, acetone precipitation and ethanol precipitation) for lipid removal from crude protein extracts were applied in different PUFAs-producing micro-organisms. Among the selective strains, Schizochytrium was used as an oleaginous strain with high lipid of 60.3 (w/w%) in biomass. The Mortierella alpina and Cunninghamella echinulata were chosen as the low-lipid-content strains with 25.8 (w/w%) and 21.8 (w/w%) of lipid in biomass, respectively. The cold shock resulted as the most effective method for lipid removed, thus obtained higher protein amount for Schizochytrium. Moreover, from the comparative proteomics for the three PUFAs-producing strains, it showed more significant proteins of up or down-regulation were explored under cold shock treatment. Therefore, the essential proteins (i.e., polyunsaturated fatty acid synthase) and regulating proteins were observed. In conclusion, this study provides a valuable and practical approach for analysis of high PUFAs-producing strains at the proteomics level, and would further accelerate the understanding of the metabolic flux in oleaginous micro-organisms.

Biological Diversity Comprising Microbial Structures of Antarctic Ice Covered Lakes

NASA Astrophysics Data System (ADS)

Matys, E. D.

2015-12-01

Analysis of microbial membrane lipids is a rapid and non-selective method for evaluating the composition of microbial communities. To fully realise the diagnostic potential of these lipids, we must first understand their structural diversity, biological sources, physiological functions, and pathways of preservation. Particular environmental conditions likely prompt the production of different membrane lipid structures. Antarctica's McMurdo Dry Valleys host numerous ice-covered lakes with sharp chemical gradients that vary in illumination, geochemical structure, and benthic mat morphologies that are structured by nutrient availability and water chemistry. The lipid contents of these benthic mats have not received extensive study nor have the communities yet been thoroughly characterized. Accordingly, a combination of lipid biomarker and nucleic acid sequence data provides the means of assessing species diversity and environmental controls on the composition and diversity of membrane lipid assemblages. We investigated the richness and diversity of benthic microbial communities and accumulated organic matter in Lake Vanda of the McMurdo Dry Valleys. We have identified diverse glycolipids, aminolipids, and phospholipids in addition to many unknown compounds that may be specific to these particular environments. Light levels fluctuate seasonally, favoring low-light-tolerant cyanobacteria and specific lipid assemblages. Adaptations to nutrient limitations are reflected in contrasting intact polar lipid assemblages. For example, under P-limiting conditions, phospholipids are subsidiary to membrane-forming lipids that do not contain P (i.e. ornithine, betaine, and sulfolipids). The bacteriohopanepolyol (BHP) composition is dominated by bacteriohopanetetrol (BHT), a ubiquitous BHP, and 2-methylhopanoids. The relative abundance of 2-methylhopanoids is unprecedented and may reflect the unusual seasonal light regime of this polar environment. By establishing correlations between environmental conditions, microbial community composition and the lipid assemblages of microbial structures in ice-covered lakes of Antarctica's McMurdo Dry Valleys, our data provides important ecological and evolutionary insights into these unusual environments.

Lipid Cell Biology: A Focus on Lipids in Cell Division.

PubMed

Storck, Elisabeth M; Özbalci, Cagakan; Eggert, Ulrike S

2018-06-20

Cells depend on hugely diverse lipidomes for many functions. The actions and structural integrity of the plasma membrane and most organelles also critically depend on membranes and their lipid components. Despite the biological importance of lipids, our understanding of lipid engagement, especially the roles of lipid hydrophobic alkyl side chains, in key cellular processes is still developing. Emerging research has begun to dissect the importance of lipids in intricate events such as cell division. This review discusses how these structurally diverse biomolecules are spatially and temporally regulated during cell division, with a focus on cytokinesis. We analyze how lipids facilitate changes in cellular morphology during division and how they participate in key signaling events. We identify which cytokinesis proteins are associated with membranes, suggesting lipid interactions. More broadly, we highlight key unaddressed questions in lipid cell biology and techniques, including mass spectrometry, advanced imaging, and chemical biology, which will help us gain insights into the functional roles of lipids.

All-atom simulations and free-energy calculations of coiled-coil peptides with lipid bilayers: binding strength, structural transition, and effect on lipid dynamics

NASA Astrophysics Data System (ADS)

Woo, Sun Young; Lee, Hwankyu

2016-03-01

Peptides E and K, which are synthetic coiled-coil peptides for membrane fusion, were simulated with lipid bilayers composed of lipids and cholesterols at different ratios using all-atom models. We first calculated free energies of binding from umbrella sampling simulations, showing that both E and K peptides tend to adsorb onto the bilayer surface, which occurs more strongly in the bilayer composed of smaller lipid headgroups. Then, unrestrained simulations show that K peptides more deeply insert into the bilayer with partially retaining the helical structure, while E peptides less insert and predominantly become random coils, indicating the structural transition from helices to random coils, in quantitative agreement with experiments. This is because K peptides electrostatically interact with lipid phosphates, as well as because hydrocarbons of lysines of K peptide are longer than those of glutamic acids of E peptide and thus form stronger hydrophobic interactions with lipid tails. This deeper insertion of K peptide increases the bilayer dynamics and a vacancy below the peptide, leading to the rearrangement of smaller lipids. These findings help explain the experimentally observed or proposed differences in the insertion depth, binding strength, and structural transition of E and K peptides, and support the snorkeling effect.

All-atom simulations and free-energy calculations of coiled-coil peptides with lipid bilayers: binding strength, structural transition, and effect on lipid dynamics.

PubMed

Woo, Sun Young; Lee, Hwankyu

2016-03-01

Peptides E and K, which are synthetic coiled-coil peptides for membrane fusion, were simulated with lipid bilayers composed of lipids and cholesterols at different ratios using all-atom models. We first calculated free energies of binding from umbrella sampling simulations, showing that both E and K peptides tend to adsorb onto the bilayer surface, which occurs more strongly in the bilayer composed of smaller lipid headgroups. Then, unrestrained simulations show that K peptides more deeply insert into the bilayer with partially retaining the helical structure, while E peptides less insert and predominantly become random coils, indicating the structural transition from helices to random coils, in quantitative agreement with experiments. This is because K peptides electrostatically interact with lipid phosphates, as well as because hydrocarbons of lysines of K peptide are longer than those of glutamic acids of E peptide and thus form stronger hydrophobic interactions with lipid tails. This deeper insertion of K peptide increases the bilayer dynamics and a vacancy below the peptide, leading to the rearrangement of smaller lipids. These findings help explain the experimentally observed or proposed differences in the insertion depth, binding strength, and structural transition of E and K peptides, and support the snorkeling effect.

76 FR 55689 - Endocrinologic and Metabolic Drugs Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-08

..., Center for Drug Evaluation and Research, Food and Drug Administration, 10903 New Hampshire Ave., Bldg. 31.../Schering-Plough) Singapore Company, LLC. Simvastatin lowers lipids (fats that circulate in the bloodstream... in producing lipids in the body, and ezetimibe lowers lipids by inhibiting the absorption of...

Pasting characteristics of starch-lipid composites

USDA-ARS?s Scientific Manuscript database

Starch-lipid composites (SLC) have been used as fat replacers and stabilizers in beef patties, dairy products, and baked goods. The SLC are produced by mixing aqueous starch slurry with a lipid source, and steam jet-cooking. The SLC may be dried using a drum drier and then milled in a Retch mill. ...

Single Cell Oil Production from Hydrolysates of Inulin by a Newly Isolated Yeast Papiliotrema laurentii AM113 for Biodiesel Making.

PubMed

Wang, Guangyuan; Liu, Lin; Liang, Wenxing

2018-01-01

Microbial oils are among the most attractive alternative feedstocks for biodiesel production. In this study, a newly isolated yeast strain, AM113 of Papiliotrema laurentii, was identified as a potential lipid producer, which could accumulate a large amount of intracellular lipids from hydrolysates of inulin. P. laurentii AM113 was able to produce 54.6% (w/w) of intracellular oil in its cells and 18.2 g/l of dry cell mass in a fed-batch fermentation. The yields of lipid and biomass were 0.14 and 0.25 g per gram of consumed sugar, respectively. The lipid productivity was 0.092 g of oil per hour. Compositions of the fatty acids produced were C 14:0 (0.9%), C 16:0 (10.8%), C 16:1 (9.7%), C 18:0 (6.5%), C 18:1 (60.3%), and C 18:2 (11.8%). Biodiesel obtained from the extracted lipids could be burnt well. This study not only provides a promising candidate for single cell oil production, but will also probably facilitate more efficient biodiesel production.

A discrete transition zone between cuticle and cortex layers of a human hair fibre: changes observed in the presence of breast cancer.

PubMed

Lyman, Donald; Gerstmann, Paula

2017-01-01

Attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy of hair fibres shows a discrete transition zone (DTZ) between the hard protective cuticle layer and the softer elongated cortical cells of the cortex. The DTZ is composed of flattened orthocortical cells located on the outer perimeter of the cortex and appears to range in thickness between 2 and 3.6 μm. The inner surface of the DTZ, adjacent to the elongated cortical cells that make up the core of the hair fibre, is irregular. ATR-FT-IR analyses of these flattened orthocortical cells indicate major changes in the molecular structure of keratins found in this transition zone. Other studies have identified cells that produce keratins that are distinct from alpha keratins found in the elongated heterocortical cells in the hair fibre core. These distinct keratins appear to be produced in the lower region of the hair follicle at the interface between the cuticle and cortex. The DTZ is also the region where ATR-FT-IR spectroscopy studies identified changes in C-H bending of lipid esters indicative of breast cancer. Lipid ester absorption bands at 1738 and 1732 cm -1 , present in non-cancer hair, are absent in the cancer hair and a new ester band absorbing at 1736 cm -1 is observed. When the breast cancer is clinically removed, the 1736 cm -1 ester band absorption and the increase in the 1446-1456 C-H-bending absorption ratio are no longer observed. This suggests that biomarkers produced by the breast cancer interact with stem or other cells near the lower region of the follicle, controlling the amount and type of lipid esters in the DTZ.

Major roles for minor bacterial lipids identified by mass spectrometry.

PubMed

Garrett, Teresa A

2017-11-01

Mass spectrometry of lipids, especially those isolated from bacteria, has ballooned over the past two decades, affirming in the process the complexity of the lipidome. With this has come the identification of new and interesting lipid structures. Here is an overview of several novel lipids, from both Gram-negative and Gram-positive bacteria with roles in health and disease, whose structural identification was facilitated using mass spectrometry. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016 Elsevier B.V. All rights reserved.

FAX1, a Novel Membrane Protein Mediating Plastid Fatty Acid Export

PubMed Central

Li, Nannan; Gügel, Irene Luise; Giavalisco, Patrick; Zeisler, Viktoria; Schreiber, Lukas; Soll, Jürgen; Philippar, Katrin

2015-01-01

Fatty acid synthesis in plants occurs in plastids, and thus, export for subsequent acyl editing and lipid assembly in the cytosol and endoplasmatic reticulum is required. Yet, the transport mechanism for plastid fatty acids still remains enigmatic. We isolated FAX1 (fatty acid export 1), a novel protein, which inserts into the chloroplast inner envelope by α-helical membrane-spanning domains. Detailed phenotypic and ultrastructural analyses of FAX1 mutants in Arabidopsis thaliana showed that FAX1 function is crucial for biomass production, male fertility and synthesis of fatty acid-derived compounds such as lipids, ketone waxes, or pollen cell wall material. Determination of lipid, fatty acid, and wax contents by mass spectrometry revealed that endoplasmatic reticulum (ER)-derived lipids decreased when FAX1 was missing, but levels of several plastid-produced species increased. FAX1 over-expressing lines showed the opposite behavior, including a pronounced increase of triacyglycerol oils in flowers and leaves. Furthermore, the cuticular layer of stems from fax1 knockout lines was specifically reduced in C29 ketone wax compounds. Differential gene expression in FAX1 mutants as determined by DNA microarray analysis confirmed phenotypes and metabolic imbalances. Since in yeast FAX1 could complement for fatty acid transport, we concluded that FAX1 mediates fatty acid export from plastids. In vertebrates, FAX1 relatives are structurally related, mitochondrial membrane proteins of so-far unknown function. Therefore, this protein family might represent a powerful tool not only to increase lipid/biofuel production in plants but also to explore novel transport systems involved in vertebrate fatty acid and lipid metabolism. PMID:25646734

A Lipid Extraction and Analysis Method for Characterizing Soil Microbes in Experiments with Many Samples

PubMed Central

Oates, Lawrence G.; Read, Harry W.; Gutknecht, Jessica L. M.; Duncan, David S.; Balser, Teri B.; Jackson, Randall D.

2017-01-01

Microbial communities are important drivers and regulators of ecosystem processes. To understand how management of ecosystems may affect microbial communities, a relatively precise but effort-intensive technique to assay microbial community composition is phospholipid fatty acid (PLFA) analysis. PLFA was developed to analyze phospholipid biomarkers, which can be used as indicators of microbial biomass and the composition of broad functional groups of fungi and bacteria. It has commonly been used to compare soils under alternative plant communities, ecology, and management regimes. The PLFA method has been shown to be sensitive to detecting shifts in microbial community composition. An alternative method, fatty acid methyl ester extraction and analysis (MIDI-FA) was developed for rapid extraction of total lipids, without separation of the phospholipid fraction, from pure cultures as a microbial identification technique. This method is rapid but is less suited for soil samples because it lacks an initial step separating soil particles and begins instead with a saponification reaction that likely produces artifacts from the background organic matter in the soil. This article describes a method that increases throughput while balancing effort and accuracy for extraction of lipids from the cell membranes of microorganisms for use in characterizing both total lipids and the relative abundance of indicator lipids to determine soil microbial community structure in studies with many samples. The method combines the accuracy achieved through PLFA profiling by extracting and concentrating soil lipids as a first step, and a reduction in effort by saponifying the organic material extracted and processing with the MIDI-FA method as a second step. PMID:28745639

Lipid drug conjugate nanoparticle as a novel lipid nanocarrier for the oral delivery of decitabine: ex vivo gut permeation studies

NASA Astrophysics Data System (ADS)

Neupane, Yub Raj; Sabir, M. D.; Ahmad, Nafees; Ali, Mushir; Kohli, Kanchan

2013-10-01

The purpose of this study was to develop lipid drug conjugate (LDC) nanoparticles of decitabine (DCB) using stearic acid as a lipid to increase the permeability of the drug along with its protection from chemical degradation. The LDC was prepared by salt formation of DCB with stearic acid and followed by cold homogenization technique to produce the LDC nanoparticles. The role of key independent variables influencing on dependent variables were determined by using a Box-Behnken design. The optimized batch revealed spherical morphology under TEM analysis with particle size of 202.6 ± 1.65 nm and 0.334 ± 0.987 PDI. The zeta potential and %EE were found to be -33.6 ± 0.845 mV and 68.89% ± 0.59 respectively. Lyophilized powder showed the crystalline structure under DSC analysis. In vitro release studies showed the initial burst release followed by a sustained release up to 24 h in PBS pH 7.4 and the data were further studied using release kinetic models which revealed the first-order model as a best-fitting model. Ex vivo gut permeation studies proved that the formulation containing lipid and surfactants has a higher permeability than the plain drug solution with nearly fourfold increase in the apparent permeability coefficients. Finally, LDC nanoparticles prepared by using stearic acid as a lipid and surfactants as Tween 80, Poloxamer 188, and Labrasol in equal ratio possess high potential for the oral delivery of hydrophilic drugs.

CD1a on Langerhans cells controls inflammatory skin diseases

PubMed Central

Yongqing, Tang; Kim, Jessica; Hughes, Victoria A.; Nours, Jérôme Le; Marquez, Elsa A.; Purcell, Anthony W.; Wan, Qi; Sugita, Masahiko

2016-01-01

CD1a is a lipid-presenting molecule abundantly expressed on Langerhans cells. However, the in vivo role of CD1a remains unclear, principally because CD1a is lacking in mice. Using CD1a-transgenic mice, we show that the plant-derived lipid urushiol triggers CD1a-dependent skin inflammation, driven by CD4+ T cells producing IL-17 and IL-22. Human subjects with poison ivy dermatitis showed a similar cytokine signature following CD1a-mediated urushiol recognition. Among different urushiol congeners, we identified diunsaturated pentadecylcatechol (C15:2) as the dominant antigen for CD1a-restricted T cells. We determined the crystal structure of the CD1a-urushiol (C15:2) complex, demonstrating the molecular basis of urushiol interaction with the antigen-binding cleft of CD1a. In a mouse model and psoriasis patients, CD1a amplified inflammatory responses mediated by TH17 cells reactive with self lipid antigens. Treatment with blocking antibodies against CD1a alleviated skin inflammation. Thus, we propose CD1a as a potential therapeutic target in inflammatory skin diseases. PMID:27548435

A network model of successive partitioning-limited solute diffusion through the stratum corneum.

PubMed

Schumm, Phillip; Scoglio, Caterina M; van der Merwe, Deon

2010-02-07

As the most exposed point of contact with the external environment, the skin is an important barrier to many chemical exposures, including medications, potentially toxic chemicals and cosmetics. Traditional dermal absorption models treat the stratum corneum lipids as a homogenous medium through which solutes diffuse according to Fick's first law of diffusion. This approach does not explain non-linear absorption and irregular distribution patterns within the stratum corneum lipids as observed in experimental data. A network model, based on successive partitioning-limited solute diffusion through the stratum corneum, where the lipid structure is represented by a large, sparse, and regular network where nodes have variable characteristics, offers an alternative, efficient, and flexible approach to dermal absorption modeling that simulates non-linear absorption data patterns. Four model versions are presented: two linear models, which have unlimited node capacities, and two non-linear models, which have limited node capacities. The non-linear model outputs produce absorption to dose relationships that can be best characterized quantitatively by using power equations, similar to the equations used to describe non-linear experimental data.

Reactive Oxygen Species Inactivation of Surfactant Involves Structural and Functional Alterations to Surfactant Proteins SP-B and SP-C

PubMed Central

Rodríguez-Capote, Karina; Manzanares, Dahis; Haines, Thomas; Possmayer, Fred

2006-01-01

Exposing bovine lipid extract surfactant (BLES), a clinical surfactant, to reactive oxygen species arising from hypochlorous acid or the Fenton reaction resulted in an increase in lipid (conjugated dienes, lipid aldehydes) and protein (carbonyls) oxidation products and a reduction in surface activity. Experiments where oxidized phospholipids (PL) were mixed with BLES demonstrated that this addition hampered BLES biophysical activity. However the effects were only moderately greater than with control PL. These results imply a critical role for protein oxidation. BLES oxidation by either method resulted in alterations in surfactant proteins SP-B and SP-C, as evidenced by altered Coomassie blue and silver staining. Western blot analyses showed depressed reactivity with specific antibodies. Oxidized SP-C showed decreased palmitoylation. Reconstitution experiments employing PL, SP-B, and SP-C isolated from control or oxidized BLES demonstrated that protein oxidation was more deleterious than lipid oxidation. Furthermore, addition of control SP-B can improve samples containing oxidized SP-C, but not vice versa. We conclude that surfactant oxidation arising from reactive oxygen species generated by air pollution or leukocytes interferes with surfactant function through oxidation of surfactant PL and proteins, but that protein oxidation, in particular SP-B modification, produces the major deleterious effects. PMID:16443649

SOLEIL shining on the solution-state structure of biomacromolecules by synchrotron X-ray footprinting at the Metrology beamline.

PubMed

Baud, A; Aymé, L; Gonnet, F; Salard, I; Gohon, Y; Jolivet, P; Brodolin, K; Da Silva, P; Giuliani, A; Sclavi, B; Chardot, T; Mercère, P; Roblin, P; Daniel, R

2017-05-01

Synchrotron X-ray footprinting complements the techniques commonly used to define the structure of molecules such as crystallography, small-angle X-ray scattering and nuclear magnetic resonance. It is remarkably useful in probing the structure and interactions of proteins with lipids, nucleic acids or with other proteins in solution, often better reflecting the in vivo state dynamics. To date, most X-ray footprinting studies have been carried out at the National Synchrotron Light Source, USA, and at the European Synchrotron Radiation Facility in Grenoble, France. This work presents X-ray footprinting of biomolecules performed for the first time at the X-ray Metrology beamline at the SOLEIL synchrotron radiation source. The installation at this beamline of a stopped-flow apparatus for sample delivery, an irradiation capillary and an automatic sample collector enabled the X-ray footprinting study of the structure of the soluble protein factor H (FH) from the human complement system as well as of the lipid-associated hydrophobic protein S3 oleosin from plant seed. Mass spectrometry analysis showed that the structural integrity of both proteins was not affected by the short exposition to the oxygen radicals produced during the irradiation. Irradiated molecules were subsequently analysed using high-resolution mass spectrometry to identify and locate oxidized amino acids. Moreover, the analyses of FH in its free state and in complex with complement C3b protein have allowed us to create a map of reactive solvent-exposed residues on the surface of FH and to observe the changes in oxidation of FH residues upon C3b binding. Studies of the solvent accessibility of the S3 oleosin show that X-ray footprinting offers also a unique approach to studying the structure of proteins embedded within membranes or lipid bodies. All the biomolecular applications reported herein demonstrate that the Metrology beamline at SOLEIL can be successfully used for synchrotron X-ray footprinting of biomolecules.

UV Lamp as a Facile Ozone Source for Structural Analysis of Unsaturated Lipids Via Electrospray Ionization-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Stinson, Craig A.; Zhang, Wenpeng; Xia, Yu

2017-12-01

Ozonolysis of alkene functional groups is a type of highly specific and effective chemical reaction, which has found increasing applications in structural analysis of unsaturated lipids via coupling with mass spectrometry (MS). In this work, we utilized a low-pressure mercury lamp (6 W) to initiate ozonolysis inside electrospray ionization (ESI) sources. By placing the lamp near a nanoESI emitter that partially transmits 185 nm ultraviolet (UV) emission from the lamp, dissolved dioxygen in the spray solution was converted into ozone, which subsequently cleaved the double bonds within fatty acyls of lipids. Solvent conditions, such as presence of water and acid solution pH, were found to be critical in optimizing ozonolysis yields. Fast (on seconds time scale) and efficient (50%-100% yield) ozonolysis was achieved for model unsaturated phospholipids and fatty acids with UV lamp-induced ozonolysis incorporated on a static and an infusion nanoESI source. The method was able to differentiate double bond location isomers and identify the geometry of the double bond based on yield. The analytical utility of UV lamp-induced ozonolysis was further demonstrated by implementation on a liquid chromatography (LC)-MS platform. Ozonolysis was effected in a flow microreactor that was made from ozone permeable tubing, so that ambient ozone produced by the lamp irradiation could diffuse into the reactor and induce online ozonolysis post-LC separation and before ESI-MS.

Detailed dimethylacetal and fatty acid composition of rumen content from lambs fed lucerne or concentrate supplemented with soybean oil.

PubMed

Alves, Susana P; Santos-Silva, José; Cabrita, Ana R J; Fonseca, António J M; Bessa, Rui J B

2013-01-01

Lipid metabolism in the rumen is responsible for the complex fatty acid profile of rumen outflow compared with the dietary fatty acid composition, contributing to the lipid profile of ruminant products. A method for the detailed dimethylacetal and fatty acid analysis of rumen contents was developed and applied to rumen content collected from lambs fed lucerne or concentrate based diets supplemented with soybean oil. The methodological approach developed consisted on a basic/acid direct transesterification followed by thin-layer chromatography to isolate fatty acid methyl esters from dimethylacetal, oxo- fatty acid and fatty acid dimethylesters. The dimethylacetal composition was quite similar to the fatty acid composition, presenting even-, odd- and branched-chain structures. Total and individual odd- and branched-chain dimethylacetals were mostly affected by basal diet. The presence of 18:1 dimethylacetals indicates that biohydrogenation intermediates might be incorporated in structural microbial lipids. Moreover, medium-chain fatty acid dimethylesters were identified for the first time in the rumen content despite their concentration being relatively low. The fatty acids containing 18 carbon-chain lengths comprise the majority of the fatty acids present in the rumen content, most of them being biohydrogenation intermediates of 18:2n-6 and 18:3n-3. Additionally, three oxo- fatty acids were identified in rumen samples, and 16-O-18:0 might be produced during biohydrogenation of the 18:3n-3.

Understanding microbial ecology can help improve biogas production in AD.

PubMed

Ferguson, Robert M W; Coulon, Frédéric; Villa, Raffaella

2018-06-16

454-Pyrosequencing and lipid fingerprinting were used to link anaerobic digestion (AD) process parameters (pH, alkalinity, volatile fatty acids (VFAs), biogas production and methane content) with the reactor microbial community structure and composition. AD microbial communities underwent stress conditions after changes in organic loading rate and digestion substrates. 454-Pyrosequencing analysis showed that, irrespectively of the substrate digested, methane content and pH were always significantly, and positively, correlated with community evenness. In AD, microbial communities with more even distributions of diversity are able to use parallel metabolic pathways and have greater functional stability; hence, they are capable of adapting and responding to disturbances. In all reactors, a decrease in methane content to <30% was always correlated with a 50% increase of Firmicutes sequences (particularly in operational taxonomic units (OTUs) related to Ruminococcaceae and Veillonellaceae). Whereas digesters producing higher methane content (above 60%), contained a high number of sequences related to Synergistetes and unidentified bacterial OTUs. Finally, lipid fingerprinting demonstrated that, under stress, the decrease in archaeal biomass was higher than the bacterial one, and that archaeal Phospholipid etherlipids (PLEL) levels were correlated to reactor performances. These results demonstrate that, across a number of parameters such as lipids, alpha and beta diversity, and OTUs, knowledge of the microbial community structure can be used to predict, monitor, or optimise AD performance. Copyright © 2018 Elsevier B.V. All rights reserved.

Proposal for a common nomenclature for fragment ions in mass spectra of lipids

PubMed Central

Hartler, Jürgen; Christiansen, Klaus; Gallego, Sandra F.; Peng, Bing; Ahrends, Robert

2017-01-01

Advances in mass spectrometry-based lipidomics have in recent years prompted efforts to standardize the annotation of the vast number of lipid molecules that can be detected in biological systems. These efforts have focused on cataloguing, naming and drawing chemical structures of intact lipid molecules, but have provided no guidelines for annotation of lipid fragment ions detected using tandem and multi-stage mass spectrometry, albeit these fragment ions are mandatory for structural elucidation and high confidence lipid identification, especially in high throughput lipidomics workflows. Here we propose a nomenclature for the annotation of lipid fragment ions, describe its implementation and present a freely available web application, termed ALEX123 lipid calculator, that can be used to query a comprehensive database featuring curated lipid fragmentation information for more than 430,000 potential lipid molecules from 47 lipid classes covering five lipid categories. We note that the nomenclature is generic, extendable to stable isotope-labeled lipid molecules and applicable to automated annotation of fragment ions detected by most contemporary lipidomics platforms, including LC-MS/MS-based routines. PMID:29161304

Proposal for a common nomenclature for fragment ions in mass spectra of lipids.

PubMed

Pauling, Josch K; Hermansson, Martin; Hartler, Jürgen; Christiansen, Klaus; Gallego, Sandra F; Peng, Bing; Ahrends, Robert; Ejsing, Christer S

2017-01-01

Advances in mass spectrometry-based lipidomics have in recent years prompted efforts to standardize the annotation of the vast number of lipid molecules that can be detected in biological systems. These efforts have focused on cataloguing, naming and drawing chemical structures of intact lipid molecules, but have provided no guidelines for annotation of lipid fragment ions detected using tandem and multi-stage mass spectrometry, albeit these fragment ions are mandatory for structural elucidation and high confidence lipid identification, especially in high throughput lipidomics workflows. Here we propose a nomenclature for the annotation of lipid fragment ions, describe its implementation and present a freely available web application, termed ALEX123 lipid calculator, that can be used to query a comprehensive database featuring curated lipid fragmentation information for more than 430,000 potential lipid molecules from 47 lipid classes covering five lipid categories. We note that the nomenclature is generic, extendable to stable isotope-labeled lipid molecules and applicable to automated annotation of fragment ions detected by most contemporary lipidomics platforms, including LC-MS/MS-based routines.

Sterol Synthesis in Diverse Bacteria.

PubMed

Wei, Jeremy H; Yin, Xinchi; Welander, Paula V

2016-01-01

Sterols are essential components of eukaryotic cells whose biosynthesis and function has been studied extensively. Sterols are also recognized as the diagenetic precursors of steranes preserved in sedimentary rocks where they can function as geological proxies for eukaryotic organisms and/or aerobic metabolisms and environments. However, production of these lipids is not restricted to the eukaryotic domain as a few bacterial species also synthesize sterols. Phylogenomic studies have identified genes encoding homologs of sterol biosynthesis proteins in the genomes of several additional species, indicating that sterol production may be more widespread in the bacterial domain than previously thought. Although the occurrence of sterol synthesis genes in a genome indicates the potential for sterol production, it provides neither conclusive evidence of sterol synthesis nor information about the composition and abundance of basic and modified sterols that are actually being produced. Here, we coupled bioinformatics with lipid analyses to investigate the scope of bacterial sterol production. We identified oxidosqualene cyclase (Osc), which catalyzes the initial cyclization of oxidosqualene to the basic sterol structure, in 34 bacterial genomes from five phyla (Bacteroidetes, Cyanobacteria, Planctomycetes, Proteobacteria, and Verrucomicrobia) and in 176 metagenomes. Our data indicate that bacterial sterol synthesis likely occurs in diverse organisms and environments and also provides evidence that there are as yet uncultured groups of bacterial sterol producers. Phylogenetic analysis of bacterial and eukaryotic Osc sequences confirmed a complex evolutionary history of sterol synthesis in this domain. Finally, we characterized the lipids produced by Osc-containing bacteria and found that we could generally predict the ability to synthesize sterols. However, predicting the final modified sterol based on our current knowledge of sterol synthesis was difficult. Some bacteria produced demethylated and saturated sterol products even though they lacked homologs of the eukaryotic proteins required for these modifications emphasizing that several aspects of bacterial sterol synthesis are still completely unknown.

Bioprospecting microbes for single-cell oil production from starchy wastes.

PubMed

Chaturvedi, Shivani; Kumari, Arti; Nain, Lata; Khare, Sunil K

2018-03-16

Production of lipid from oleaginous yeast using starch as a carbon source is not a common practice; therefore, the purpose of this investigation was to explore the capability of starch assimilating microbes to produce oil, which was determined in terms of biomass weight, productivity, and lipid yield. Saccharomyces pastorianus, Rhodotorula mucilaginosa, Rhodotorula glutinis, and fungal isolate Ganoderma wiiroense were screened for the key parameters. The optimization was also performed by one-factor-at-a-time approach. Considering the specific yield of lipid and cell dry weight yield, R. glutinis and R. mucilaginosa showed superiority over other strains. G. wiiroense, a new isolate, would also be a promising strain for starch waste utilization in terms of extracellular and intracellular specific yield of lipids. Extracellular specific yield of lipid was highest in R. glutinis culture (0.025 g g -1 of biomass) followed by R. mucilaginosa (0.022 g g -1 of biomass) and G. wiiroense (0.020 g g -1 of biomass). Intracellular lipid was again highest in R. glutinis (0.048 g g -1 of biomass). The most prominent fatty acid methyl esters among the lipid as detected by GC-MS were saturated lipids mainly octadecanoic acid, tetradecanoate, and hexadecanoate. Extracellular lipid produced on starch substrate waste would be a cost-effective alternative for energy-intensive extraction process in biodiesel industry.

Composite bacterial hopanoids and their microbial producers across oxygen gradients in the water column of the California Current.

PubMed

Kharbush, Jenan J; Ugalde, Juan A; Hogle, Shane L; Allen, Eric E; Aluwihare, Lihini I

2013-12-01

Hopanoids are pentacyclic triterpenoid lipids produced by many prokaryotes as cell membrane components. The structural variations of composite hopanoids, or bacteriohopanepolyols (BHPs), produced by various bacterial genera make them potentially useful molecular biomarkers of bacterial communities and metabolic processes in both modern and ancient environments. Building on previous work suggesting that organisms in low-oxygen environments are important contributors to BHP production in the marine water column and that there may be physiological roles for BHPs specific to these environments, this study investigated the relationship between trends in BHP structural diversity and abundance and the genetic diversity of BHP producers for the first time in a low-oxygen environment of the Eastern Tropical North Pacific. Amplification of the hopanoid biosynthesis gene for squalene hopene cyclase (sqhC) indicated far greater genetic diversity than would be predicted by examining BHP structural diversity alone and that greater sqhC genetic diversity exists in the marine environment than is represented by cultured representatives and most marine metagenomes. In addition, the genetic relationships in this data set suggest microaerophilic environments as potential "hot spots" of BHP production. Finally, structural analysis of BHPs showed that an isomer of the commonly observed BHP bacteriohopanetetrol may be linked to a producer that is more abundant in low-oxygen environments. Results of this study increase the known diversity of BHP producers and provide a detailed phylogeny with implications for the role of hopanoids in modern bacteria, as well as the evolutionary history of hopanoid biosynthesis, both of which are important considerations for future interpretations of the marine sedimentary record.

Transport rates of a glutamate transporter homologue are influenced by the lipid bilayer.

PubMed

McIlwain, Benjamin C; Vandenberg, Robert J; Ryan, Renae M

2015-04-10

The aspartate transporter from Pyrococcus horikoshii (GltPh) is a model for the structure of the SLC1 family of amino acid transporters. Crystal structures of GltPh provide insight into mechanisms of ion coupling and substrate transport; however, structures have been solved in the absence of a lipid bilayer so they provide limited information regarding interactions that occur between the protein and lipids of the membrane. Here, we investigated the effect of the lipid environment on aspartate transport by reconstituting GltPh into liposomes of defined lipid composition where the primary lipid is phosphatidylethanolamine (PE) or its methyl derivatives. We showed that the rate of aspartate transport and the transmembrane orientation of GltPh were influenced by the primary lipid in the liposomes. In PE liposomes, we observed the highest transport rate and showed that 85% of the transporters were orientated right-side out, whereas in trimethyl PE liposomes, 50% of transporters were right-side out, and we observed a 4-fold reduction in transport rate. Differences in orientation can only partially explain the lipid composition effect on transport rate. Crystal structures of GltPh revealed a tyrosine residue (Tyr-33) that we propose interacts with lipid headgroups during the transport cycle. Based on site-directed mutagenesis, we propose that a cation-π interaction between Tyr-33 and the lipid headgroups can influence conformational flexibility of the trimerization domain and thus the rate of transport. These results provide a specific example of how interactions between membrane lipids and membrane-bound proteins can influence function and highlight the importance of the role of the membrane in transporter function. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Transport Rates of a Glutamate Transporter Homologue Are Influenced by the Lipid Bilayer*

PubMed Central

McIlwain, Benjamin C.; Vandenberg, Robert J.; Ryan, Renae M.

2015-01-01

The aspartate transporter from Pyrococcus horikoshii (GltPh) is a model for the structure of the SLC1 family of amino acid transporters. Crystal structures of GltPh provide insight into mechanisms of ion coupling and substrate transport; however, structures have been solved in the absence of a lipid bilayer so they provide limited information regarding interactions that occur between the protein and lipids of the membrane. Here, we investigated the effect of the lipid environment on aspartate transport by reconstituting GltPh into liposomes of defined lipid composition where the primary lipid is phosphatidylethanolamine (PE) or its methyl derivatives. We showed that the rate of aspartate transport and the transmembrane orientation of GltPh were influenced by the primary lipid in the liposomes. In PE liposomes, we observed the highest transport rate and showed that 85% of the transporters were orientated right-side out, whereas in trimethyl PE liposomes, 50% of transporters were right-side out, and we observed a 4-fold reduction in transport rate. Differences in orientation can only partially explain the lipid composition effect on transport rate. Crystal structures of GltPh revealed a tyrosine residue (Tyr-33) that we propose interacts with lipid headgroups during the transport cycle. Based on site-directed mutagenesis, we propose that a cation-π interaction between Tyr-33 and the lipid headgroups can influence conformational flexibility of the trimerization domain and thus the rate of transport. These results provide a specific example of how interactions between membrane lipids and membrane-bound proteins can influence function and highlight the importance of the role of the membrane in transporter function. PMID:25713135

Diphytanoyl lipids as model systems for studying membrane-active peptides.

PubMed

Kara, Sezgin; Afonin, Sergii; Babii, Oleg; Tkachenko, Anton N; Komarov, Igor V; Ulrich, Anne S

2017-10-01

The branched chains in diphytanoyl lipids provide membranes with unique properties, such as high chemical/physical stability, low water permeability, and no gel-to-fluid phase transition at ambient temperature. Synthetic diphytanoyl phospholipids are often used as model membranes for electrophysiological experiments. To evaluate whether these sturdy lipids are also suitable for solid-state NMR, we have examined their interactions with a typical amphiphilic peptide in comparison with straight-chain lipids. First, their phase properties were monitored using 31 P NMR, and the structural behaviour of the antimicrobial peptide PGLa was studied by 19 F NMR and circular dichroism in oriented membrane samples. Only lipids with choline headgroups (DPhPC) were found to form stable lipid bilayers in oriented samples, while DPhPG, DPhPE and DPhPS display non-lamellar structures. Hence, the experimental temperature and hydration are crucial factors when using supported diphytanoyl lipids, as both parameters must be maintained in an appropriate range to avoid the formation of non-bilayer structures. For the same reason, a high content of other diphytanoyl lipids besides DPhPC in mixed lipid systems is not favourable. Unlike the situation in straight-chain membranes, we found that the α-helical PGLa was not able to insert into the tightly packed fluid bilayer of DPhPC but remained in a surface-bound state even at very high peptide concentration. This behaviour can be explained by the high cohesivity and the negative spontaneous curvature of the diphytanoyl lipids. These characteristic features must therefore be taken into consideration, both, in electrophysiological studies, and when interpreting the structural behaviour of membrane-active peptides in such lipid environment. Copyright © 2017 Elsevier B.V. All rights reserved.

Skin lipid structure controls water permeability in snake molts.

PubMed

Torri, Cristian; Mangoni, Alfonso; Teta, Roberta; Fattorusso, Ernesto; Alibardi, Lorenzo; Fermani, Simona; Bonacini, Irene; Gazzano, Massimo; Burghammer, Manfred; Fabbri, Daniele; Falini, Giuseppe

2014-01-01

The role of lipids in controlling water exchange is fundamentally a matter of molecular organization. In the present study we have observed that in snake molt the water permeability drastically varies among species living in different climates and habitats. The analysis of molts from four snake species: tiger snake, Notechis scutatus, gabon viper, Bitis gabonica, rattle snake, Crotalus atrox, and grass snake, Natrix natrix, revealed correlations between the molecular composition and the structural organization of the lipid-rich mesos layer with control in water exchange as a function of temperature. It was discovered, merging data from micro-diffraction and micro-spectroscopy with those from thermal, NMR and chromatographic analyses, that this control is generated from a sophisticated structural organization that changes size and phase distribution of crystalline domains of specific lipid molecules as a function of temperature. Thus, the results of this research on four snake species suggest that in snake skins different structured lipid layers have evolved and adapted to different climates. Moreover, these lipid structures can protect, "safety", the snakes from water lost even at temperatures higher than those of their usual habitat. Copyright © 2013 Elsevier Inc. All rights reserved.

Machine-Learned Data Structures of Lipid Marker Serum Concentrations in Multiple Sclerosis Patients Differ from Those in Healthy Subjects

PubMed Central

Lötsch, Jörn; Thrun, Michael; Lerch, Florian; Brunkhorst, Robert; Schiffmann, Susanne; Thomas, Dominique; Tegder, Irmgard; Geisslinger, Gerd; Ultsch, Alfred

2017-01-01

Lipid signaling has been suggested to be a major pathophysiological mechanism of multiple sclerosis (MS). With the increasing knowledge about lipid signaling, acquired data become increasingly complex making bioinformatics necessary in lipid research. We used unsupervised machine-learning to analyze lipid marker serum concentrations, pursuing the hypothesis that for the most relevant markers the emerging data structures will coincide with the diagnosis of MS. Machine learning was implemented as emergent self-organizing feature maps (ESOM) combined with the U*-matrix visualization technique. The data space consisted of serum concentrations of three main classes of lipid markers comprising eicosanoids (d = 11 markers), ceramides (d = 10), and lyosophosphatidic acids (d = 6). They were analyzed in cohorts of MS patients (n = 102) and healthy subjects (n = 301). Clear data structures in the high-dimensional data space were observed in eicosanoid and ceramides serum concentrations whereas no clear structure could be found in lysophosphatidic acid concentrations. With ceramide concentrations, the structures that had emerged from unsupervised machine-learning almost completely overlapped with the known grouping of MS patients versus healthy subjects. This was only partly provided by eicosanoid serum concentrations. Thus, unsupervised machine-learning identified distinct data structures of bioactive lipid serum concentrations. These structures could be superimposed with the known grouping of MS patients versus healthy subjects, which was almost completely possible with ceramides. Therefore, based on the present analysis, ceramides are first-line candidates for further exploration as drug-gable targets or biomarkers in MS. PMID:28590455

Designing lipids for selective partitioning into liquid ordered membrane domains.

PubMed

Momin, Noor; Lee, Stacey; Gadok, Avinash K; Busch, David J; Bachand, George D; Hayden, Carl C; Stachowiak, Jeanne C; Sasaki, Darryl Y

2015-04-28

Self-organization of lipid molecules into specific membrane phases is key to the development of hierarchical molecular assemblies that mimic cellular structures. While the packing interaction of the lipid tails should provide the major driving force to direct lipid partitioning to ordered or disordered membrane domains, numerous examples show that the headgroup and spacer play important but undefined roles. We report here the development of several new biotinylated lipids that examine the role of spacer chemistry and structure on membrane phase partitioning. The new lipids were prepared with varying lengths of low molecular weight polyethylene glycol (EGn) spacers to examine how spacer hydrophilicity and length influence their partitioning behavior following binding with FITC-labeled streptavidin in liquid ordered (Lo) and liquid disordered (Ld) phase coexisting membranes. Partitioning coefficients (Kp Lo/Ld) of the biotinylated lipids were determined using fluorescence measurements in studies with giant unilamellar vesicles (GUVs). Compared against DPPE-biotin, DPPE-cap-biotin, and DSPE-PEG2000-biotin lipids, the new dipalmityl-EGn-biotin lipids exhibited markedly enhanced partitioning into liquid ordered domains, achieving Kp of up to 7.3 with a decaethylene glycol spacer (DP-EG10-biotin). We further demonstrated biological relevance of the lipids with selective partitioning to lipid raft-like domains observed in giant plasma membrane vesicles (GPMVs) derived from mammalian cells. Our results found that the spacer group not only plays a pivotal role for designing lipids with phase selectivity but may also influence the structural order of the domain assemblies.

DMSO Induces Dehydration near Lipid Membrane Surfaces

PubMed Central

Cheng, Chi-Yuan; Song, Jinsuk; Pas, Jolien; Meijer, Lenny H.H.; Han, Songi

2015-01-01

Dimethyl sulfoxide (DMSO) has been broadly used in biology as a cosolvent, a cryoprotectant, and an enhancer of membrane permeability, leading to the general assumption that DMSO-induced structural changes in cell membranes and their hydration water play important functional roles. Although the effects of DMSO on the membrane structure and the headgroup dehydration have been extensively studied, the mechanism by which DMSO invokes its effect on lipid membranes and the direct role of water in this process are unresolved. By directly probing the translational water diffusivity near unconfined lipid vesicle surfaces, the lipid headgroup mobility, and the repeat distances in multilamellar vesicles, we found that DMSO exclusively weakens the surface water network near the lipid membrane at a bulk DMSO mole fraction (XDMSO) of <0.1, regardless of the lipid composition and the lipid phase. Specifically, DMSO was found to effectively destabilize the hydration water structure at the lipid membrane surface at XDMSO <0.1, lower the energetic barrier to dehydrate this surface water, whose displacement otherwise requires a higher activation energy, consequently yielding compressed interbilayer distances in multilamellar vesicles at equilibrium with unaltered bilayer thicknesses. At XDMSO >0.1, DMSO enters the lipid interface and restricts the lipid headgroup motion. We postulate that DMSO acts as an efficient cryoprotectant even at low concentrations by exclusively disrupting the water network near the lipid membrane surface, weakening the cohesion between water and adhesion of water to the lipid headgroups, and so mitigating the stress induced by the volume change of water during freeze-thaw. PMID:26200868

The “Beta-Clasp” model of apolipoprotein A-I - a lipid-free solution structure determined by electron paramagnetic resonance spectroscopy

PubMed Central

Lagerstedt, Jens O.; Budamagunta, Madhu S.; Liu, Grace S.; DeValle, Nicole C.; Voss, John C.; Oda, Michael N.

2012-01-01

Apolipoprotein A-I (apoA-I) is the major protein component of high density lipoproteins (HDL) and plays a central role in cholesterol metabolism. The lipid-free / lipid-poor form of apoA-I is the preferred substrate for the ATP-binding cassette transporter A1 (ABCA1). The interaction of apoA-I with ABCA1 leads to the formation of cholesterol laden high density lipoprotein (HDL) particles, a key step in reverse cholesterol transport and the maintenance of cholesterol homeostasis. Knowledge of the structure of lipid-free apoA-I is essential to understanding its critical interaction with ABCA1 and the molecular mechanisms underlying HDL biogenesis. We therefore examined the structure of lipid-free apoA-I by electron paramagnetic resonance spectroscopy (EPR). Through site directed spin label EPR, we mapped the secondary structure of apoA-I and identified sites of spin coupling as residues 26, 44, 64, 167, 217 and 226. We capitalize on the fact that lipid-free apoA-I self-associates in an anti-parallel manner in solution. We employed these sites of spin coupling to define the central plane in the dimeric apoA-I complex. Applying both the constraints of dipolar coupling with the EPR-derived pattern of solvent accessibility, we assembled the secondary structure into a tertiary context, providing a solution structure for lipid-free apoA-I. PMID:22245143

Impact of membrane lipid composition on the structure and stability of the transmembrane domain of amyloid precursor protein

PubMed Central

Dominguez, Laura; Foster, Leigh; Straub, John E.; Thirumalai, D.

2016-01-01

Cleavage of the amyloid precursor protein (APP) by γ-secretase is a crucial first step in the evolution of Alzheimer’s disease. To discover the cleavage mechanism, it is urgent to predict the structures of APP monomers and dimers in varying membrane environments. We determined the structures of the C9923−55 monomer and homodimer as a function of membrane lipid composition using a multiscale simulation approach that blends atomistic and coarse-grained models. We demonstrate that the C9923−55 homodimer structures form a heterogeneous ensemble with multiple conformational states, each stabilized by characteristic interpeptide interactions. The relative probabilities of each conformational state are sensitive to the membrane environment, leading to substantial variation in homodimer peptide structure as a function of membrane lipid composition or the presence of an anionic lipid environment. In contrast, the helicity of the transmembrane domain of monomeric C991−55 is relatively insensitive to the membrane lipid composition, in agreement with experimental observations. The dimer structures of human EphA2 receptor depend on the lipid environment, which we show is linked to the location of the structural motifs in the dimer interface, thereby establishing that both sequence and membrane composition modulate the complete energy landscape of membrane-bound proteins. As a by-product of our work, we explain the discrepancy in structures predicted for C99 congener homodimers in membrane and micelle environments. Our study provides insight into the observed dependence of C99 protein cleavage by γ-secretase, critical to the formation of amyloid-β protein, on membrane thickness and lipid composition. PMID:27559086

Highly stable and self-repairing membrane-mimetic 2D nanomaterials assembled from lipid-like peptoids

DOE PAGES

Jin, Haibao; Jiao, Fang; Daily, Michael D.; ...

2016-07-12

Two-dimensional (2D) materials with molecular-scale thickness have attracted increasing interest for separation, electronic, catalytic, optical, energy and biomedical applications. Although extensive research on 2D materials, such as graphene and graphene oxide, has been performed in recent years, progress is limited on self-assembly of 2D materials from sequence-specific macromolecules, especially from synthetic sequences that could exhibit lipid-like self-assembly of bilayer sheets and mimic membrane proteins for functions. The creation of such new class of materials could enable development of highly stable biomimetic membranes that exhibit cell-membrane-like molecular transport with exceptional selectively and high transport rates. Here we demonstrate self-assembly of lipid-likemore » 12-mer peptoids into extremely stable, crystalline, flexible and free-standing 2D membrane materials. As with cell membranes, upon exposure to external stimuli, these materials exhibit changes in thickness, varying from 3.5 nm to 5.6 nm. We find that self-assembly occurs through a facile crystallization process, in which inter-peptoid hydrogen bonds and enhanced hydrophobic interactions drive the formation of a highly-ordered structure. Molecular simulation confirms this is the energetically favored structure. Displaying functional groups at arbitrary locations of membrane-forming peptoids produces membranes with similar structures. This research further shows that single-layer membranes can be coated onto substrate surfaces. Moreover, membranes with mechanically-induced defects can self-repair. Given that peptoids are sequence-specific and exhibit protein-like molecular recognition with enhanced stability, we anticipate our membranes to be a robust platform tailored to specific applications.« less

Highly stable and self-repairing membrane-mimetic 2D nanomaterials assembled from lipid-like peptoids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Haibao; Jiao, Fang; Daily, Michael D.

Two-dimensional (2D) materials with molecular-scale thickness have attracted increasing interest for separation, electronic, catalytic, optical, energy and biomedical applications. Although extensive research on 2D materials, such as graphene and graphene oxide, has been performed in recent years, progress is limited on self-assembly of 2D materials from sequence-specific macromolecules, especially from synthetic sequences that could exhibit lipid-like self-assembly of bilayer sheets and mimic membrane proteins for functions. The creation of such new class of materials could enable development of highly stable biomimetic membranes that exhibit cell-membrane-like molecular transport with exceptional selectively and high transport rates. Here we demonstrate self-assembly of lipid-likemore » 12-mer peptoids into extremely stable, crystalline, flexible and free-standing 2D membrane materials. As with cell membranes, upon exposure to external stimuli, these materials exhibit changes in thickness, varying from 3.5 nm to 5.6 nm. We find that self-assembly occurs through a facile crystallization process, in which inter-peptoid hydrogen bonds and enhanced hydrophobic interactions drive the formation of a highly-ordered structure. Molecular simulation confirms this is the energetically favored structure. Displaying functional groups at arbitrary locations of membrane-forming peptoids produces membranes with similar structures. This research further shows that single-layer membranes can be coated onto substrate surfaces. Moreover, membranes with mechanically-induced defects can self-repair. Given that peptoids are sequence-specific and exhibit protein-like molecular recognition with enhanced stability, we anticipate our membranes to be a robust platform tailored to specific applications.« less

Hacking an Algal Transcription Factor for Lipid Biosynthesis.

PubMed

Chen, Xiulai; Hu, Guipeng; Liu, Liming

2018-03-01

Transcriptional engineering is a viable means for engineering microalgae to produce lipid, but it often results in a trade-off between production and growth. A recent study shows that engineering a single transcriptional regulator enables efficient carbon partitioning to lipid biosynthesis with high biomass productivity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evidence for Lipid Packaging in the Crystal Structure of the GM2-Activator Complex with Platelet Activating Factor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, Christine S.; Mi, Li-Zhi; Rastinejad, Fraydoon

2010-11-16

GM2-activator protein (GM2-AP) is a lipid transfer protein that has the ability to stimulate the enzymatic processing of gangliosides as well as T-cell activation through lipid presentation. Our previous X-ray crystallographic studies of GM2-AP have revealed a large lipid binding pocket as the central overall feature of the structure with non-protein electron density within this pocket suggesting bound lipid. To extend these studies, we present here the 2 {angstrom} crystal structure of GM2-AP complexed with platelet activating factor (PAF). PAF is a potent phosphoacylglycerol whose toxic patho-physiological effects can be inhibited by GM2-AP. The structure shows an ordered arrangement ofmore » two bound lipids and a fatty acid molecule. One PAF molecule binds in an extended conformation within the hydrophobic channel that has an open and closed conformation, and was seen to contain bound phospholipid in the low pH apo structure. The second molecule is submerged inside the pocket in a U-shaped conformation with its head group near the single polar residue S141. It was refined as lyso-PAF as it lacks electron density for the sn-2 acetate group. The alkyl chains of PAF interact through van der Waals contacts, while the head groups bind in different environments with their phosphocholine moieties in contact with aromatic rings (Y137, F80). The structure has revealed further insights into the lipid binding properties of GM2-AP, suggesting an unexpected unique mode of lipid packaging that may explain the efficiency of GM2-AP in inhibiting the detrimental biological effects of PAF.« less

Detection of outer membrane vesicles in Synechocystis PCC 6803

PubMed Central

Pardo, Yehudah A.; Florez, Catalina; Baker, Kristopher M.; Schertzer, Jeffrey W.; Mahler, Gretchen J.

2015-01-01

It has been well established that many species of Gram-negative bacteria release nanoscale outer membrane vesicles (OMVs) during normal growth. Furthermore, the roles of these structures in heterotrophic bacteria have been extensively characterized. However, little is known about the existence or function of OMVs in photoautotrophs. In the present study, we report for the first time the production of OMVs by the model photosynthetic organism Synechocystis sp. PCC 6803, a species of biotechnological importance. We detected extracellular proteins and lipids in cell-free supernatants derived from Synechocystis culture, yet the cytoplasmic and thylakoid membrane markers NADH oxidase and chlorophyll were absent. This indicated that the extracellular proteins and lipids derived from the outer membrane, and not from cell lysis. Furthermore, we identified spherical structures within the expected size range of OMVs in Synechocystis culture using scanning electron microscopy. Taken together, these results suggest that the repertoire of Gram-negative bacteria that are known to produce OMVs may be expanded to include Synechocystis PCC6803. Because of the considerable genetic characterization of Synechocystis in particular, our discovery has the potential to support novel biotechnological applications as well. PMID:26363014

Synthesis of structured lipid enriched with omega fatty acids and sn-2 palmitic acid by enzymatic esterification and its incorporation in powdered infant formula.

PubMed

Nagachinta, Supakana; Akoh, Casimir C

2013-05-08

Structured lipid (SL) enriched with arachidonic (ARA) and docosahexaenoic (DHA) acids was produced from tripalmitin using Lipozyme TL IM. The effects of acyl donors, that is, free fatty acids vs fatty acid ethyl esters, on the reactions were compared. The highest total incorporation of ARA and DHA was obtained when the reaction continued for 24 h, at a substrate mole ratio of 9, using free fatty acids as acyl donors (acidolysis). The SL prepared by a large-scale acidolysis reaction contained 17.69 ± 0.09% total ARA, 10.75 ± 0.15% total DHA, and 48.53 ± 1.40% sn-2 palmitic acid. SL thermograms exhibited multiple peaks indicating complexity of the triacylglycerol (TAG) distribution. RP-HPLC analysis of SL revealed nine of 26 TAG molecular species that were similar to those of human milk fat. Powdered infant formulas containing the SL were prepared by wet-mixing/spray-drying and dry-blending methods. Formula prepared with microencapsulated SL and the dry-blending method had better oxidative stability and color quality.

Nitrogen Starvation Induced Oxidative Stress in an Oil-Producing Green Alga Chlorella sorokiniana C3

PubMed Central

He, Chen-Liu; Wang, Qiang

2013-01-01

Microalgal lipid is one of the most promising feedstocks for biodiesel production. Chlorella appears to be a particularly good option, and nitrogen (N) starvation is an efficient environmental pressure used to increase lipid accumulation in Chlorella cells. The effects of N starvation of an oil-producing wild microalga, Chlorella sorokiniana C3, on lipid accumulation were investigated using thin layer chromatography (TLC), confocal laser scanning microscopy (CLSM) and flow cytometry (FCM). The results showed that N starvation resulted in lipid accumulation in C. sorokiniana C3 cells, oil droplet (OD) formation and significant lipid accumulation in cells were detected after 2 d and 8 d of N starvation, respectively. During OD formation, reduced photosynthetic rate, respiration rate and photochemistry efficiency accompanied by increased damage to PSII were observed, demonstrated by chlorophyll (Chl) fluorescence, 77K fluorescence and oxygen evolution tests. In the mean time the rate of cyclic electron transportation increased correspondingly to produce more ATP for triacylglycerols (TAGs) synthesis. And 0.5 d was found to be the turning point for the early stress response and acclimation of cells to N starvation. Increased level of membrane peroxidation was also observed during OD formation, and superoxide dismutase (SOD), peroxide dismutase (POD) and catalase (CAT) enzyme activity assays suggested impaired reactive oxygen species (ROS) scavenging ability. Significant neutral lipid accumulation was also observed by artificial oxidative stress induced by H2O2 treatment. These results suggested coupled neutral lipid accumulation and oxidative stress during N starvation in C. sorokiniana C3. PMID:23874918

Neutron scattering to study membrane systems: from lipid vesicles to living cells.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nickels, Jonathan D.; Chatterjee, Sneha; Stanley, Christopher B.

The existence and role of lateral lipid organization in biological membranes has been studied and contested for more than 30 years. Lipid domains, or rafts, are hypothesized as scalable compartments in biological membranes, providing appropriate physical environments to their resident membrane proteins. This implies that lateral lipid organization is associated with a range of biological functions, such as protein co-localization, membrane trafficking, and cell signaling, to name just a few. Neutron scattering techniques have proven to be an excellent tool to investigate these structural features in model lipids, and more recently, in living cells. I will discuss our recent workmore » using neutrons to probe the structure and mechanical properties in model lipid systems and our current efforts in using neutrons to probe the structure and organization of the bilayer in a living cell. These efforts in living cells have used genetic and biochemical strategies to generate a large neutron scattering contrast, making the membrane visible. I will present our results showing in vivo bilayer structure and discuss the outlook for this approach.« less

Electrostatic swelling of bicontinuous cubic lipid phases.

PubMed

Tyler, Arwen I I; Barriga, Hanna M G; Parsons, Edward S; McCarthy, Nicola L C; Ces, Oscar; Law, Robert V; Seddon, John M; Brooks, Nicholas J

2015-04-28

Lipid bicontinuous cubic phases have attracted enormous interest as bio-compatible scaffolds for use in a wide range of applications including membrane protein crystallisation, drug delivery and biosensing. One of the major bottlenecks that has hindered exploitation of these structures is an inability to create targeted highly swollen bicontinuous cubic structures with large and tunable pore sizes. In contrast, cubic structures found in vivo have periodicities approaching the micron scale. We have been able to engineer and control highly swollen bicontinuous cubic phases of spacegroup Im3m containing only lipids by (a) increasing the bilayer stiffness by adding cholesterol and (b) inducing electrostatic repulsion across the water channels by addition of anionic lipids to monoolein. By controlling the composition of the ternary mixtures we have been able to achieve lattice parameters up to 470 Å, which is 5 times that observed in pure monoolein and nearly twice the size of any lipidic cubic phase reported previously. These lattice parameters significantly exceed the predicted maximum swelling for bicontinuous cubic lipid structures, which suggest that thermal fluctuations should destroy such phases for lattice parameters larger than 300 Å.

Soy proteins and isoflavones reduce interleukin-6 but not serum lipids in older women: a randomized controlled trial☆,☆☆

PubMed Central

Mangano, Kelsey M.; Hutchins-Wiese, Heather L.; Kenny, Anne M.; Walsh, Stephen J.; Abourizk, Robin H.; Bruno, Richard S.; Lipcius, Rosanne; Fall, Pamela; Kleppinger, Alison; Kenyon-Pesce, Lisa; Prestwood, Karen M.; Kerstetter, Jane E.

2015-01-01

Soy foods contain several components, notably, isoflavones and amino acids, that may improve cardiovascular health. We evaluated the long-term effect of soy protein and/or soy isoflavones supplementation on serum lipids and inflammatory markers using a 1-year randomized, double-blind, placebo-control, clinical trial in 131 healthy ambulatory women older than 60 years. We hypothesized that soy protein, in combination with isoflavones, would have the largest positive effect on coronary heart disease risk factors (serum lipids and inflammatory markers) compared with either intervention alone and that, within groups receiving isoflavones, equol producers would have more positive effects on coronary heart disease risk factors than nonequol producers. After a 1-month baseline period, participants were randomized into 1 of 4 intervention groups: soy protein (18 g/d) and isoflavone tablets (105 mg/d isoflavone aglycone equivalents), soy protein and placebo tablets, control protein and isoflavone tablets, or control protein and placebo tablets. T Tests were used to assess differences between equol and nonequol producers. Ninety-seven women completed the trial. Consumption of protein powder and isoflavone tablets did not differ among groups, and compliance with study powder and tablets was 79% and 90%, respectively. After 1 year, in the entire population, there were either no or little effects on serum lipids and inflammatory markers, regardless of treatment group. Equol producers, when analyzed separately, had significant improvements in total cholesterol/high-density lipoprotein and low-density lipoprotein/high-density lipoprotein ratios (−5.9%, P = .02; −7.2%, P = .04 respectively). Soy protein and isoflavone (either alone or together) did not impact serum lipids or inflammatory markers. Therefore, they should not be considered an effective intervention to prevent cardiovascular disease because of lipid modification in healthy late postmenopausal women lacking the ability to produce equol. PMID:24267042

Organic Matter Polymerization by Disulfide Bonding Near the Chemocline in Cariaco Basin

NASA Astrophysics Data System (ADS)

Raven, M. R.; Adkins, J. F.; Sessions, A. L.

2013-12-01

The preservation of organic carbon in sediments as kerogen is an essential pathway in the global carbon cycle, but the chemical reactions involved in kerogen formation remain poorly understood. Previous researchers have found that many sediments deposited under euxinic conditions contain sulfur-bearing non-polar lipids as well as disulfide bonds among lipid and carbohydrate monomers. It remains unclear, however, when during organic matter decomposition and diagenesis these different sulfur-bearing structures form, and how different environmental conditions affect the extent of organic matter sulfurization. We investigate organic sulfurization processes armed with a technique for measuring the sulfur-isotopic compositions of individual organosulfur compounds by coupled gas chromatography - inductively coupled plasma mass spectrometry. Organic compounds were extracted from sediments and water column sediment traps from Cariaco Basin, a euxinic basin in the Caribbean Sea. We measured the sulfur-isotopic compositions of both non-polar lipids and of derivatized disulfide-bound compounds from eight sediment trap profiles and a six-meter-long sediment core. In Cariaco Basin, lipid sulfurization processes appear to begin near the chemocline and continue in sediments on timescales of thousands of years. Slow diagenetic sulfurization in sediments produces lipid monomers with sulfur atoms in ring structures that are 34S-depleted relative to coexisting dissolved sulfide. Lipid monomers become progressively enriched in 34S over time, indicating ongoing formation coinciding with an increase in the amount of total sulfur in bulk kerogen. One of the most abundant monomers observed in Cariaco sediments, a phytol-related thiophene, is also produced intermittently near the chemocline. Phytol thiophene δ34S values in sediment traps are similar to those observed in shallow Cariaco sediments except during occasional ';enrichment events,' when phytol thiophene δ34S values increase to as high as -2‰. In contrast, disulfide bonding appears to affect both lipids and carbohydrates and occur exclusively at the chemocline on very short timescales of days to weeks. In both the water column and the sediments, the sulfur isotope ratios of disulfide-bound monosaccharides are dramatically 34S-enriched relative to dissolved sulfide at the chemocline (~-30‰), ranging from -11‰ to +9‰. Disulfide-bound phytenes, which likely derive from the same precursor compounds as phytol thiophenes, were observed in only a few of the sediment trap extracts and have sulfur-isotopic compositions near +4.5‰. These 34S-enriched compositions indicate that the source of sulfur for rapid disulfide bonding may be an intermediate sulfur species that is not in isotopic equilibrium with dissolved sulfide. Significantly, δ34S values for disulfide-bound compounds in Cariaco Basin appear to be set at the chemocline and stable during subsequent diagenesis, opening the possibility that organic sulfur isotopes may archive information about environmental conditions at the chemocline in low-maturity sediments. Disulfide bonding does not, however, appear to be the major process driving slower diagenetic sulfur incorporation into kerogen. Compound-specific organic sulfur isotope analysis makes it possible to distinguish the products of different lipid and carbohydrate sulfurization processes for the first time.

Structural changes in plastids of developing Splachnum ampullaceum sporophytes and relationship to odour production.

PubMed

McCuaig, B; Dufour, S C; Raguso, R A; Bhatt, A P; Marino, P

2015-03-01

Many mosses of the family Splachnaceae are entomophilous and rely on flies for spore dispersal. Splachnum ampullaceum produces a yellow- or pink-coloured hypophysis that releases volatile compounds, attracting flies to the mature moss. The biosynthetic sources of the visual and aromatic cues within the hypophysis have not been identified, and may be either symbiotic cyanobacteria or chromoplasts that break down lipids into volatile compounds. Here, we used transmission electron microscopy and gas chromatography-mass spectrometry (GC-MS) to investigate the sources of these attractants, focusing on different tissues and stages of maturation. Microscopy revealed an abundance of plastids within the hypophysis, while no symbiotic bacteria were observed. During plant maturation, plastids differentiated from amyloplasts with large starch granules to photosynthetic chloroplasts and finally to chromoplasts with lipid accumulations. We used GC-MS to identify over 50 volatile organic compounds from mature sporophytes including short-chain oxygenated compounds, unsaturated irregular terpenoids, fatty acid-derived 6- and 8-carbon alcohols and ketones, and the aromatic compounds acetophenone and p-cresol. The hypophysis showed localised production of pungent volatiles, mainly short-chain fermentation compounds and p-cresol. Some of these volatiles have been shown to be produced from lipid oxidase degradation of linolenic acid within chromoplasts. However, other compounds (such as cyclohexanecarboxylic acid esters) may have a microbial origin. Further investigation is necessary to identify the origin of fly attractants in these mosses. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

The effect of low calorie structured lipid palm mid fraction, virgin coconut oil and canola oil blend on rats body weight and plasma profile

NASA Astrophysics Data System (ADS)

Bakar, Aftar Mizan Abu; Ayob, Mohd Khan; Maskat, Mohamad Yusof

2016-11-01

This study was carried out to evaluate the effect of low calorie cocoa butter substitutes, the structured lipids (SLs) on rats' body weight and plasma lipid levels. The SLs were developed from a ternary blending of palm mid fraction (PMF), virgin coconut oil (VCO) and canola oil (CO). The optimized blends were then underwent enzymatic acidolysisusing sn-1,3-specific lipase. This process produced A12, a SL which hasa solid fat content almost comparable to cocoa butter but has low calories. Therefore, it has a high potential to be used for cocoa butter substitute with great nutritional values. Fourty two Sprague Dawley rats were divided into 6 groups and were force feed for a period of 2 months (56 days) and the group were Control 1(rodent chow), Control 2(cocoa butter), Control 3(PMF:VCO:CO 90:5:5 - S3 blend), High doseSL (A12:C8+S3), Medium dose SL (A12:C8+S3) and Low dose SL (A12:C8+S3). The body weight of each rat was recorded once daily. The plasma profile of treated and control rats, which comprised of total cholesterol, HDL cholesterol, LDL cholesterol and triglyceride was measured on day 0 (baseline) and day 56 (post-treatment). Low calorie structured lipid (SL) was synthesized through acidolysis reaction using sn 1-3-specific lipase of ThermomycesLanuginos (TLIM) among 25 samples with optimum parameter obtained from the RSM. Blood samples for plasma separation were collected using cardiac puncture and requiring anesthesia via tail vein(Anesthetics for rats: Ketamine/Xylazine) for day 0 and day 56. Results of the study showed that rats in group 1 and group 2 has gained weight by 1.66 g and 4.75 g respectively and showed significant difference (p<0.05). In contrast, G3, G4, G5 and G6 showed significant difference (p<0.05) with weight loss by 2.16 g, 10.71g, 7.27 g and 3.23 g respectively 7.27 g and 3.23 g respectively after the treatment. Biochemical analyses on the ratsplasma lipid revealed that the total blood cholesterol content of rats fed with either low dosage (1.39 ± 0.08 mmol/L), medium dosage (1.40 ± 0.08 mmol/L) or high dosage (1.42 ± 0.07 mmol/L) of SLs contains C8:0 for 56 days was significantly lower (p<0.05) than day 0. However, total cholesterol for G1 and G2 was also significantly different (p<0.05) when compared after the treatment. There were no significant differences (p>0.05) between G3 on day 0 and 56 days for total cholesterol. Meanwhile, total plasma HDLcholesterol content of rats fed with C8:0 was significantly higher (p<0.05) than the baseline (day 0) and the total plasma LDL cholesterol levels of rats in G4, G5 and G6 were significantly lower (p<0.05) than the baseline (day 0). In conclusion, combination of medium-chain fatty acid (C8:0) which produced low calorie structured lipids effectively altered the plasma cholesterol levels of experimental rats.

An Anionic Phospholipid Enables the Hydrophobic Surfactant Proteins to Alter Spontaneous Curvature

PubMed Central

Chavarha, Mariya; Loney, Ryan W.; Rananavare, Shankar B.; Hall, Stephen B.

2013-01-01

The hydrophobic surfactant proteins, SP-B and SP-C, greatly accelerate the adsorption of the surfactant lipids to an air/water interface. Previous studies of factors that affect curvature suggest that vesicles may adsorb via a rate-limiting structure with prominent negative curvature, in which the hydrophilic face of the lipid leaflets is concave. To determine if SP-B and SP-C might promote adsorption by inducing negative curvature, we used small-angle x-ray scattering to test whether the physiological mixture of the two proteins affects the radius of cylindrical monolayers in the inverse hexagonal phase. With dioleoyl phosphatidylethanolamine alone, the proteins had no effect on the hexagonal lattice constant, suggesting that the proteins fail to insert into the cylindrical monolayers. The surfactant lipids also contain ∼10% anionic phospholipids, which might allow incorporation of the cationic proteins. With 10% of the anionic dioleoyl phosphatidylglycerol added to dioleoyl phosphatidylethanolamine, the proteins induced a dose-related decrease in the hexagonal lattice constant. At 30°C, the reduction reached a maximum of 8% relative to the lipids alone at ∼1% (w/w) protein. Variation of NaCl concentration tested whether the effect of the protein represented a strictly electrostatic effect that screening by electrolyte would eliminate. With concentrations up to 3 M NaCl, the dose-related change in the hexagonal lattice constant decreased but persisted. Measurements at different hydrations determined the location of the pivotal plane and proved that the change in the lattice constant produced by the proteins resulted from a shift in spontaneous curvature. These results provide the most direct evidence yet that the surfactant proteins can induce negative curvature in lipid leaflets. This finding supports the model in which the proteins promote adsorption by facilitating the formation of a negatively curved, rate-limiting structure. PMID:23442910

Structures and properties of naturally occurring polyether antibiotics.

PubMed

Rutkowski, Jacek; Brzezinski, Bogumil

2013-01-01

Polyether ionophores represent a large group of natural, biologically active substances produced by Streptomyces spp. They are lipid soluble and able to transport metal cations across cell membranes. Several of polyether ionophores are widely used as growth promoters in veterinary. Polyether antibiotics show a broad spectrum of bioactivity ranging from antibacterial, antifungal, antiparasitic, antiviral, and tumour cell cytotoxicity. Recently, it has been shown that some of these compounds are able to selectively kill cancer stem cells and multidrug-resistant cancer cells. Thus, they are recognized as new potential anticancer drugs. The biological activity of polyether ionophores is strictly connected with their molecular structure; therefore, the purpose of this paper is to present an overview of their formula, molecular structure, and properties.

Structures and Properties of Naturally Occurring Polyether Antibiotics

PubMed Central

Rutkowski, Jacek; Brzezinski, Bogumil

2013-01-01

Polyether ionophores represent a large group of natural, biologically active substances produced by Streptomyces spp. They are lipid soluble and able to transport metal cations across cell membranes. Several of polyether ionophores are widely used as growth promoters in veterinary. Polyether antibiotics show a broad spectrum of bioactivity ranging from antibacterial, antifungal, antiparasitic, antiviral, and tumour cell cytotoxicity. Recently, it has been shown that some of these compounds are able to selectively kill cancer stem cells and multidrug-resistant cancer cells. Thus, they are recognized as new potential anticancer drugs. The biological activity of polyether ionophores is strictly connected with their molecular structure; therefore, the purpose of this paper is to present an overview of their formula, molecular structure, and properties. PMID:23586016

Xenon and Other Volatile Anesthetics Change Domain Structure in Model Lipid Raft Membranes

PubMed Central

Weinrich, Michael; Worcester, David L.

2014-01-01

Inhalation anesthetics have been in clinical use for over 160 years, but the molecular mechanisms of action continue to be investigated. Direct interactions with ion channels received much attention after it was found that anesthetics do not change the structure of homogeneous model membranes. However, it was recently found that halothane, a prototypical anesthetic, changes domain structure of a binary lipid membrane. The noble gas xenon is an excellent anesthetic and provides a pivotal test of the generality of this finding, extended to ternary lipid raft mixtures. We report that xenon and conventional anesthetics change the domain equilibrium in two canonical ternary lipid raft mixtures. These findings demonstrate a membrane-mediated mechanism whereby inhalation anesthetics can affect the lipid environment of trans-membrane proteins. PMID:24299622

Characterization of 3D Voronoi Tessellation Nearest Neighbor Lipid Shells Provides Atomistic Lipid Disruption Profile of Protein Containing Lipid Membranes

PubMed Central

Cheng, Sara Y.; Duong, Hai V.; Compton, Campbell; Vaughn, Mark W.; Nguyen, Hoa; Cheng, Kwan H.

2015-01-01

Quantifying protein-induced lipid disruptions at the atomistic level is a challenging problem in membrane biophysics. Here we propose a novel 3D Voronoi tessellation nearest-atom-neighbor shell method to classify and characterize lipid domains into discrete concentric lipid shells surrounding membrane proteins in structurally heterogeneous lipid membranes. This method needs only the coordinates of the system and is independent of force fields and simulation conditions. As a proof-of-principle, we use this multiple lipid shell method to analyze the lipid disruption profiles of three simulated membrane systems: phosphatidylcholine, phosphatidylcholine/cholesterol, and beta-amyloid/phosphatidylcholine/cholesterol. We observed different atomic volume disruption mechanisms due to cholesterol and beta-amyloid Additionally, several lipid fractional groups and lipid-interfacial water did not converge to their control values with increasing distance or shell order from the protein. This volume divergent behavior was confirmed by bilayer thickness and chain orientational order calculations. Our method can also be used to analyze high-resolution structural experimental data. PMID:25637891

Novel resveratrol nanodelivery systems based on lipid nanoparticles to enhance its oral bioavailability

PubMed Central

Neves, Ana Rute; Lúcio, Marlene; Martins, Susana; Lima, José Luís Costa; Reis, Salette

2013-01-01

Introduction Resveratrol is a polyphenol found in grapes and red wines. Interest in this polyphenol has increased due to its pharmacological cardio- and neuroprotective, chemopreventive, and antiaging effects, among others. Nevertheless, its pharmacokinetic properties are less favorable, since the compound has poor bioavailability, low water solubility, and is chemically unstable. To overcome these problems, we developed two novel resveratrol nanodelivery systems based on lipid nanoparticles to enhance resveratrol’s oral bioavailability for further use in medicines, supplements, and nutraceuticals. Methods and materials Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) loaded with resveratrol were successfully produced by a modified hot homogenization technique. These were completely characterized to evaluate the quality of the developed resveratrol-loaded nanoparticles. Results Cryo-scanning electron microscopy morphology studies showed spherical and uniform nanoparticles with a smooth surface. An average resveratrol entrapment efficiency of ~70% was obtained for both SLNs and NLCs. Dynamic light scattering measurements gave a Z-average of 150–250 nm, polydispersity index of ~0.2, and a highly negative zeta potential of around −30 mV with no statistically significant differences in the presence of resveratrol. These characteristics remained unchanged for at least 2 months, suggesting good stability. Differential scanning calorimetry studies confirmed the solid state of the SLNs and NLCs at both room and body temperatures. The NLCs had a less ordered crystalline structure conferred by the inclusion of the liquid lipid, since they had lower values for phase transition temperature, melting enthalpy, and the recrystallization index. The presence of resveratrol induced a disorder in the crystal structure of the nanoparticles, suggesting a favoring of its entrapment. The in vitro release studies on conditions of storage showed a negligible resveratrol release over several hours for both nanosystems and the in vitro simulation of gastrointestinal transit showed that the resveratrol remained mostly associated with the lipid nanoparticles after their incubation in digestive fluids. Conclusion Both nanodelivery systems can be considered suitable carriers for oral administration, conferring protection to the incorporated resveratrol and allowing a controlled release after uptake. PMID:23326193

Sonic hedgehog multimerization: a self-organizing event driven by post-translational modifications?

PubMed

Koleva, Mirella V; Rothery, Stephen; Spitaler, Martin; Neil, Mark A A; Magee, Anthony I

2015-01-01

Sonic hedgehog (Shh) is a morphogen active during vertebrate development and tissue homeostasis in adulthood. Dysregulation of the Shh signalling pathway is known to incite carcinogenesis. Due to the highly lipophilic nature of this protein imparted by two post-translational modifications, Shh's method of transit through the aqueous extracellular milieu has been a long-standing conundrum, prompting the proposition of numerous hypotheses to explain the manner of its displacement from the surface of the producing cell. Detection of high molecular-weight complexes of Shh in the intercellular environment has indicated that the protein achieves this by accumulating into multimeric structures prior to release from producing cells. The mechanism of assembly of the multimers, however, has hitherto remained mysterious and contentious. Here, with the aid of high-resolution optical imaging and post-translational modification mutants of Shh, we show that the C-terminal cholesterol and the N-terminal palmitate adducts contribute to the assembly of large multimers and regulate their shape. Moreover, we show that small Shh multimers are produced in the absence of any lipid modifications. Based on an assessment of the distribution of various dimensional characteristics of individual Shh clusters, in parallel with deductions about the kinetics of release of the protein from the producing cells, we conclude that multimerization is driven by self-assembly underpinned by the law of mass action. We speculate that the lipid modifications augment the size of the multimolecular complexes through prolonging their association with the exoplasmic membrane.

Effect of Amphotericin B antibiotic on the properties of model lipid membrane

NASA Astrophysics Data System (ADS)

Kiryakova, S.; Dencheva-Zarkova, M.; Genova, J.

2014-12-01

Model membranes formed from natural and synthetic lipids are an interesting object for scientific investigations due to their similarity to biological cell membrane and their simple structure with controlled composition and properties. Amphotericin B is an important polyene antifungal antibiotic, used for treatment of systemic fungal infections. It is known from the literature that the studied antibiotic has a substantial effect on the transmembrane ionic channel structures. When applied to the lipid membranes it has the tendency to create pores and in this way to affect the structure and the properties of the membrane lipid bilayer. In this work the thermally induced shape fluctuations of giant quasi-spherical liposomes have been used to study the influence of polyene antibiotic amphotericin B on the elastic properties of model lipid membranes. It have been shown experimentally that the presence of 3 mol % of AmB in the lipid membrane reduces the bending elasticity of the lipid membrane for both studied cases: pure SOPC membrane and mixed SOPC-Cholesterol membrane. Interaction of the amphotericin B with bilayer lipid membranes containing channels have been studied in this work. Model membranes were self-assembled using the patch-clamp and tip-dip patch clamp technique. We have found that amphotericin B is an ionophore and reduces the resistance of the lipid bilayer.

Influence of lipids in the generation of phenylacetaldehyde in wort-related model systems.

PubMed

Gallardo, Emerenciana; De Schutter, David P; Zamora, Rosario; Derdelinckx, Guy; Delvaux, Freddy R; Hidalgo, Francisco J

2008-05-14

The effect of lipids on the formation of the Strecker aldehyde phenylacetaldehyde during wort boiling was studied to determine the role that small changes in the lipid content of the wort have in the production of significant flavor compounds in beer. Wort was treated with 0-2.77 mmol per liter of glucose, linoleic acid, or 2,4-decadienal and heated at 60-98 degrees C for 1 h. After this time, the amount of the Strecker aldehyde phenylacetaldehyde increased in the samples treated with linoleic acid or decadienal but not in the samples treated with glucose. Thus, the amount of phenylacetaldehyde produced in the presence of linoleic acid was 1.1-2.5 times the amount of the Strecker aldehyde produced in the control wort, and this amount increased to 3.6-4.6 times when decadienal was employed. The higher reactivity of decadienal than linoleic acid for this reaction decreased with temperature and was related to the oxidation of linoleic acid that occurred to a higher extent at higher temperatures. The above results suggest that lipids can contribute to the formation of Strecker aldehydes during wort boiling and that changes in the lipid content of the wort will produce significant changes in the formation of Strecker aldehydes in addition to other well-known consequences in beer quality and yeast metabolism. On the other hand, because of the high glucose content in wort, small changes in its content are not expected to affect the amount of Strecker aldehydes produced.

Bovine binder-of-sperm protein BSP1 promotes protrusion and nanotube formation from liposomes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lafleur, Michel, E-mail: michel.lafleur@umontreal.ca; Courtemanche, Lesley; Karlsson, Goeran

Research highlights: {yields} Binder-of-sperm protein 1 (BSP1) modifies the morphology of lipidic vesicles inducing bead necklace-like and thread-like structures. {yields} In the presence of multilamellar liposomes, BSP1 leads to the formation of long nanotubes. {yields} The insertion of BSP1 in the external lipid leaflet of membranes induces local changes in bilayer curvature. -- Abstract: Binder-of-sperm (BSP) proteins interact with sperm membranes and are proposed to extract selectively phosphatidylcholine and cholesterol from these. This change in lipid composition is a key step in sperm capacitation. The present work demonstrates that the interactions between the protein BSP1 and model membranes composed withmore » phosphatidylcholine lead to drastic changes in the morphology of the lipidic self-assemblies. Using cryo-electron microscopy and fluorescence microscopy, we show that, in the presence of the protein, the lipid vesicles elongate, and form bead necklace-like structures that evolve toward small vesicles or thread-like structures. In the presence of multilamellar vesicles, where a large reservoir of lipid is available, the presence of BSP proteins lead to the formation of long nanotubes. Long spiral-like threads, associated with lipid/protein complexes, are also observed. The local curvature of lipid membranes induced by the BSP proteins may be involved in lipid domain formation and the extraction of some lipids during the sperm maturation process.« less

Advances and unresolved challenges in the structural characterization of isomeric lipids.

PubMed

Hancock, Sarah E; Poad, Berwyck L J; Batarseh, Amani; Abbott, Sarah K; Mitchell, Todd W

2017-05-01

As the field of lipidomics grows and its application becomes wide and varied it is important that we don't forget its foundation, i.e. the identification and measurement of molecular lipids. Advances in liquid chromatography and the emergence of ion mobility as a useful tool in lipid analysis are allowing greater separation of lipid isomers than ever before. At the same time, novel ion activation techniques, such as ozone-induced dissociation, are pushing lipid structural characterization by mass spectrometry to new levels. Nevertheless, the quantitative capacity of these techniques is yet to be proven and further refinements are required to unravel the high level of lipid complexity found in biological samples. At present there is no one technique capable of providing full structural characterization of lipids from a biological sample. There are however, numerous techniques now available (as discussed in this review) that could be deployed in a targeted approach. Moving forward, the combination of advanced separation and ion activation techniques is likely to provide mass spectrometry-based lipidomics with its best opportunity to achieve complete molecular-level lipid characterization and measurement from complex mixtures. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

Nutritional Lipidomics: Molecular Metabolism, Analytics, and Diagnostics

PubMed Central

Smilowitz, Jennifer T.; Zivkovic, Angela M.; Wan, Yu-Jui Yvonne; Watkins, Steve M.; Nording, Malin L.; Hammock, Bruce D.; German, J. Bruce

2013-01-01

The field of lipidomics is providing nutritional science a more comprehensive view of lipid intermediates. Lipidomics research takes advantage of the increase in accuracy and sensitivity of mass detection of mass spectrometry with new bioinformatics toolsets to characterize the structures and abundances of complex lipids. Yet, translating lipidomics to practice via nutritional interventions is still in its infancy. No single instrumentation platform is able to solve the varying analytical challenges of the different molecular lipid species. Biochemical pathways of lipid metabolism remain incomplete and the tools to map lipid compositional data to pathways are still being assembled. Biology itself is dauntingly complex and simply separating biological structures remains a key challenge to lipidomics. Nonetheless, the strategy of combining tandem analytical methods to perform the sensitive, high-throughput, quantitative and comprehensive analysis of lipid metabolites of very large numbers of molecules is poised to drive the field forward rapidly. Among the next steps for nutrition to understand the changes in structures, compositions and function of lipid biomolecules in response to diet is to describe their distribution within discrete functional compartments-lipoproteins. Additionally, lipidomics must tackle the task of assigning the functions of lipids as signaling molecules, nutrient sensors, and intermediates of metabolic pathways. PMID:23818328

Maximally asymmetric transbilayer distribution of anionic lipids alters the structure and interaction with lipids of an amyloidogenic protein dimer bound to the membrane surface

PubMed Central

Cheng, Sara Y.; Chou, George; Buie, Creighton; Vaughn, Mark W.; Compton, Campbell; Cheng, Kwan H.

2016-01-01

We used molecular dynamics simulations to explore the effects of asymmetric transbilayer distribution of anionic phosphatidylserine (PS) lipids on the structure of a protein on the membrane surface and subsequent protein–lipid interactions. Our simulation systems consisted of an amyloidogenic, beta-sheet rich dimeric protein (D42) absorbed to the phosphatidylcholine (PC) leaflet, or protein-contact PC leaflet, of two membrane systems: a single-component PC bilayer and double PC/PS bilayers. The latter comprised of a stable but asymmetric transbilayer distribution of PS in the presence of counterions, with a 1-component PC leaflet coupled to a 1-component PS leaflet in each bilayer. The maximally asymmetric PC/PS bilayer had a non-zero transmembrane potential (TMP) difference and higher lipid order packing, whereas the symmetric PC bilayer had a zero TMP difference and lower lipid order packing under physiologically relevant conditions. Analysis of the adsorbed protein structures revealed weaker protein binding, more folding in the N-terminal domain, more aggregation of the N- and C-terminal domains and larger tilt angle of D42 on the PC leaflet surface of the PC/PS bilayer versus the PC bilayer. Also, analysis of protein-induced membrane structural disruption revealed more localized bilayer thinning in the PC/PS versus PC bilayer. Although the electric field profile in the non-protein-contact PS leaflet of the PC/PS bilayer differed significantly from that in the non-protein-contact PC leaflet of the PC bilayer, no significant difference in the electric field profile in the protein-contact PC leaflet of either bilayer was evident. We speculate that lipid packing has a larger effect on the surface adsorbed protein structure than the electric field for a maximally asymmetric PC/PS bilayer. Our results support the mechanism that the higher lipid packing in a lipid leaflet promotes stronger protein–protein but weaker protein–lipid interactions for a dimeric protein on membrane surfaces. PMID:26827904

Langmuir monolayers composed of single and double tail sulfobetaine lipids.

PubMed

Hazell, Gavin; Gee, Anthony P; Arnold, Thomas; Edler, Karen J; Lewis, Simon E

2016-07-15

Owing to structural similarities between sulfobetaine lipids and phospholipids it should be possible to form stable Langmuir monolayers from long tail sulfobetaines. By modification of the density of lipid tail group (number of carbon chains) it should also be possible to modulate the two-dimensional phase behaviour of these lipids and thereby compare with that of equivalent phospholipids. Potentially this could enable the use of such lipids for the wide array of applications that currently use phospholipids. The benefit of using sulfobetaine lipids is that they can be synthesised by a one-step reaction from cheap and readily available starting materials and will degrade via different pathways than natural lipids. The molecular architecture of the lipid can be easily modified allowing the design of lipids for specific purposes. In addition the reversal of the charge within the sulfobetaine head group relative to the charge orientation in phospholipids may modify behaviour and thereby allow for novel uses of these surfactants. Stable Langmuir monolayers were formed composed of single and double tailed sulfobetaine lipids. Surface pressure-area isotherm, Brewster Angle Microscopy and X-ray and neutron reflectometry measurements were conducted to measure the two-dimensional phase behaviour and out-of-plane structure of the monolayers as a function of molecular area. Sulfobetaine lipids are able to form stable Langmuir monolayers with two dimensional phase behaviour analogous to that seen for the well-studied phospholipids. Changing the number of carbon tail groups on the lipid from one to two promotes the existence of a liquid condensed phase due to increased Van der Waals interactions between the tail groups. Thus the structure of the monolayers appears to be defined by the relative sizes of the head and tail groups in a predictable way. However, the presence of sub-phase ions has little effect on the monolayer structure, behaviour that is surprisingly different to that seen for phospholipids. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Cultivation of Chlorella vulgaris using different sources of carbon and its impact on lipid production

NASA Astrophysics Data System (ADS)

Fransiscus, Yunus; Purwanto, Edy

2017-05-01

A cultivation process of Chlorella vulgaris has been done in different treatment to investigate the optimum condition for lipid production. Firstly, autotroph and heterotroph condition have been applied to test the significance impact of carbon availability to the growth and lipid production of Chlorella vulgaris. And for the same purpose, heterotroph condition using glucose, fructose and sucrose as carbon sources was independently implemented. The growth rate of Chlorella vulgaris in autotroph condition was much slower than those in heterotroph. The different sources of carbon gave no significant different in the growth pattern, but in term of lipid production it was presented a considerable result. At lower concentration (3 and 6 gr/L) of carbon sources there was only slight different in lipid production level. At higher concentration (12 gr/L) glucose as a carbon source produced the highest result, 60.18% (w/w) compared to fructose and sucrose that produced 27.34% (w/w) and 18.19% (w/w) respectively.

The CD1 family: serving lipid antigens to T cells since the Mesozoic era.

PubMed

Zajonc, Dirk M

2016-08-01

Class I-like CD1 molecules are in a family of antigen-presenting molecules that bind lipids and lipopeptides, rather than peptides for immune surveillance by T cells. Since CD1 lacks the high degree of polymorphism found in their major histocompatibility complex (MHC) class I molecules, different species express different numbers of CD1 isotypes, likely to be able to present structurally diverse classes of lipid antigens. In this review, we will present a historical overview of the structures of the different human CD1 isotypes and also discuss species-specific adaptations of the lipid-binding groove. We will discuss how single amino acid changes alter the shape and volume of the CD1 binding groove, how these minor changes can give rise to different numbers of binding pockets, and how these pockets affect the lipid repertoire that can be presented by any given CD1 protein. We will compare the structures of various lipid antigens and finally, we will discuss recognition of CD1-presented lipid antigens by antigen receptors on T cells (TCRs).

Structure-function insights into direct lipid transfer between membranes by Mmm1-Mdm12 of ERMES.

PubMed

Kawano, Shin; Tamura, Yasushi; Kojima, Rieko; Bala, Siqin; Asai, Eri; Michel, Agnès H; Kornmann, Benoît; Riezman, Isabelle; Riezman, Howard; Sakae, Yoshitake; Okamoto, Yuko; Endo, Toshiya

2018-03-05

The endoplasmic reticulum (ER)-mitochondrial encounter structure (ERMES) physically links the membranes of the ER and mitochondria in yeast. Although the ER and mitochondria cooperate to synthesize glycerophospholipids, whether ERMES directly facilitates the lipid exchange between the two organelles remains controversial. Here, we compared the x-ray structures of an ERMES subunit Mdm12 from Kluyveromyces lactis with that of Mdm12 from Saccharomyces cerevisiae and found that both Mdm12 proteins possess a hydrophobic pocket for phospholipid binding. However in vitro lipid transfer assays showed that Mdm12 alone or an Mmm1 (another ERMES subunit) fusion protein exhibited only a weak lipid transfer activity between liposomes. In contrast, Mdm12 in a complex with Mmm1 mediated efficient lipid transfer between liposomes. Mutations in Mmm1 or Mdm12 impaired the lipid transfer activities of the Mdm12-Mmm1 complex and furthermore caused defective phosphatidylserine transport from the ER to mitochondrial membranes via ERMES in vitro. Therefore, the Mmm1-Mdm12 complex functions as a minimal unit that mediates lipid transfer between membranes. © 2018 Kawano et al.

The CD1 family: serving lipid antigens to T cells since the Mesozoic era

PubMed Central

Zajonc, Dirk M.

2016-01-01

Class I-like CD1 molecules are in a family of antigen-presenting molecules that bind lipids and lipopeptides, rather than peptides for immune surveillance by T cells. Since CD1 lacks the high degree of polymorphism found in their major histocompatibility complex (MHC) class I molecules, different species express different numbers of CD1 isotypes, likely to be able to present structurally diverse classes of lipid antigens. In this review, we will present a historical overview of the structures of the different human CD1 isotypes and also discuss species-specific adaptations of the lipid-binding groove. We will discuss how single amino acid changes alter the shape and volume of the CD1 binding groove, how these minor changes can give rise to different numbers of binding pockets, and how these pockets affect the lipid repertoire that can be presented by any given CD1 protein. We will compare the structures of various lipid antigens and finally, we will discuss recognition of CD1-presented lipid antigens by antigen receptors on T cells (TCRs). PMID:27368414

STRUCTURAL FEATURES OF LIPID A PREPARATIONS ISOLATED FROM ESCHERICHIA COLI AND SHIGELLA FLEXNERI,

DTIC Science & Technology

to 4 in contrast to those of S . marcescens ; the configurations are probably beta. Possible structures for both lipid A’s are proposed. (Author)...An earlier report stated that the D-glucosamine units in the lipid A of Serratia marcescens were linked I to 6 and were probably in the beta

Engineering lipid structure for recognition of the liquid ordered membrane phase

DOE PAGES

Bordovsky, Stefan S.; Wong, Christopher S.; Bachand, George D.; ...

2016-08-26

The selective partitioning of lipid components in phase-separated membranes is essential for domain formation involved in cellular processes. Identifying and tracking the movement of lipids in cellular systems would be improved if we understood how to achieve selective affinity between fluorophore-labeled lipids and membrane assemblies. Furthermore, we investigated the structure and chemistry of membrane lipids to evaluate lipid designs that partition to the liquid ordered (L o) phase. A range of fluorophores at the headgroup position and lengths of PEG spacer between the lipid backbone and fluorophore were examined. On a lipid body with saturated palmityl or palmitoyl tails, wemore » found that although the lipid tails can direct selective partitioning to the L o phase through favorable packing interactions, headgroup hydrophobicity can override the partitioning behavior and direct the lipid to the disordered membrane phase (L d). The PEG spacer can serve as a buffer to mute headgroup–membrane interactions and thus improve L o phase partitioning, but its effect is limited with strongly hydrophobic fluorophore headgroups. We present a series of lipid designs leading to the development of novel fluorescently labeled lipids with selective affinity for the L o phase.« less

Engineering Lipid Structure for Recognition of the Liquid Ordered Membrane Phase.

PubMed

Bordovsky, Stefan S; Wong, Christopher S; Bachand, George D; Stachowiak, Jeanne C; Sasaki, Darryl Y

2016-11-29

The selective partitioning of lipid components in phase-separated membranes is essential for domain formation involved in cellular processes. Identifying and tracking the movement of lipids in cellular systems would be improved if we understood how to achieve selective affinity between fluorophore-labeled lipids and membrane assemblies. Here, we investigated the structure and chemistry of membrane lipids to evaluate lipid designs that partition to the liquid ordered (L o ) phase. A range of fluorophores at the headgroup position and lengths of PEG spacer between the lipid backbone and fluorophore were examined. On a lipid body with saturated palmityl or palmitoyl tails, we found that although the lipid tails can direct selective partitioning to the L o phase through favorable packing interactions, headgroup hydrophobicity can override the partitioning behavior and direct the lipid to the disordered membrane phase (L d ). The PEG spacer can serve as a buffer to mute headgroup-membrane interactions and thus improve L o phase partitioning, but its effect is limited with strongly hydrophobic fluorophore headgroups. We present a series of lipid designs leading to the development of novel fluorescently labeled lipids with selective affinity for the L o phase.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holt, Allison M; Standaert, Robert F; Jubb, Aaron M

Biological membranes, formed primarily by the self-assembly of complex mixtures of phospholipids, provide a structured scaffold for compartmentalization and structural processes in living cells. The specific physical properties of phospholipid species present in a given membrane play a key role in mediating these processes. Phosphatidylethanolamine (PE), a zwitterionic lipid present in bacterial, yeast, and mammalian cell membranes, is exceptional. In addition to undergoing the standard lipid polymorphic transition between the gel and liquid-crystalline phase, it can also assume an unusual polymorphic state, the inverse hexagonal phase (HII). Divalent cations are among the factors that drive the formation of the HIImore » phase, wherein the lipid molecules form stacked tubular structures by burying the hydrophilic head groups and exposing the hydrophobic tails to the bulk solvent. Most biological membranes contain a lipid species capable of forming the HII state suggesting that such lipid polymorphic structural states play an important role in structural biological processes such as membrane fusion. In this study, the interactions between Mg2+ and biomimetic bacterial cell membranes composed of PE and phosphatidylglycerol (PG) were probed using differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), and fluorescence spectroscopy. The lipid phase transitions were examined at varying ratios of PE to PG and upon exposure to physiologically relevant concentrations of Mg2+. An understanding of these basic interactions enhances our understanding of membrane dynamics and how membrane-mediated structural changes may occur in vivo.« less

The influence of a formula supplemented with dairy lipids and plant oils on the erythrocyte membrane omega-3 fatty acid profile in healthy full-term infants: a double-blind randomized controlled trial

PubMed Central

2012-01-01

Background Human milk is the optimal nutrition for infants. When breastfeeding is not possible, supplementation of infant formula with long chain polyunsaturated fatty acids appears to promote neurodevelopmental outcome and visual function. Plant oils, that are the only source of fat in most of infant formulas, do not contain specific fatty acids that are present in human and cow milk and do not encounter milk fat triglyceride structure. Experimental data suggest that a mix of dairy lipids and plant oils can potentiate endogenous synthesis of n-3 long chain polyunsaturated fatty acids. This trial aims to determine the effect of an infant formula supplemented with a mixture of dairy lipids and plant oils on the erythrocyte membrane omega-3 fatty acid profile in full-term infants (primary outcome). Erythrocyte membrane long chain polyunsaturated fatty acids and fatty acids content, the plasma lipid profile and the insulin-growth factor 1 level, the gastrointestinal tolerance, the changes throughout the study in blood fatty acids content, in growth and body composition are evaluated as secondary outcomes. Methods/Design In a double-blind controlled randomized trial, 75 healthy full-term infants are randomly allocated to receive for four months a formula supplemented with a mixture of dairy lipids and plant oils or a formula containing only plant oils or a formula containing plant oils supplemented with arachidonic acid and docosahexaenoic acid. Twenty-five breast-fed infants constitute the reference group. Erythrocyte membrane omega-3 fatty acid profile, long chain polyunsaturated fatty acids and the other fatty acids content, the plasma lipid profile and the insulin-growth factor 1 level are measured after four months of intervention. Gastrointestinal tolerance, the changes in blood fatty acids content, in growth and body composition, assessed by means of an air displacement plethysmography system, are also evaluated throughout the study. Discussion The achievement of an appropriate long chain polyunsaturated fatty acids status represents an important goal in neonatal nutrition. Gaining further insight in the effects of the supplementation of a formula with dairy lipids and plant oils in healthy full-term infants could help to produce a formula whose fat content, composition and structure is more similar to human milk. Trial registration ClinicalTrials.gov Identifier NCT01611649 PMID:23072617

The influence of a formula supplemented with dairy lipids and plant oils on the erythrocyte membrane omega-3 fatty acid profile in healthy full-term infants: a double-blind randomized controlled trial.

PubMed

Giannì, Maria Lorella; Roggero, Paola; Baudry, Charlotte; Ligneul, Amandine; Morniroli, Daniela; Garbarino, Francesca; le Ruyet, Pascale; Mosca, Fabio

2012-10-17

Human milk is the optimal nutrition for infants. When breastfeeding is not possible, supplementation of infant formula with long chain polyunsaturated fatty acids appears to promote neurodevelopmental outcome and visual function. Plant oils, that are the only source of fat in most of infant formulas, do not contain specific fatty acids that are present in human and cow milk and do not encounter milk fat triglyceride structure. Experimental data suggest that a mix of dairy lipids and plant oils can potentiate endogenous synthesis of n-3 long chain polyunsaturated fatty acids. This trial aims to determine the effect of an infant formula supplemented with a mixture of dairy lipids and plant oils on the erythrocyte membrane omega-3 fatty acid profile in full-term infants (primary outcome). Erythrocyte membrane long chain polyunsaturated fatty acids and fatty acids content, the plasma lipid profile and the insulin-growth factor 1 level, the gastrointestinal tolerance, the changes throughout the study in blood fatty acids content, in growth and body composition are evaluated as secondary outcomes. In a double-blind controlled randomized trial, 75 healthy full-term infants are randomly allocated to receive for four months a formula supplemented with a mixture of dairy lipids and plant oils or a formula containing only plant oils or a formula containing plant oils supplemented with arachidonic acid and docosahexaenoic acid. Twenty-five breast-fed infants constitute the reference group. Erythrocyte membrane omega-3 fatty acid profile, long chain polyunsaturated fatty acids and the other fatty acids content, the plasma lipid profile and the insulin-growth factor 1 level are measured after four months of intervention. Gastrointestinal tolerance, the changes in blood fatty acids content, in growth and body composition, assessed by means of an air displacement plethysmography system, are also evaluated throughout the study. The achievement of an appropriate long chain polyunsaturated fatty acids status represents an important goal in neonatal nutrition. Gaining further insight in the effects of the supplementation of a formula with dairy lipids and plant oils in healthy full-term infants could help to produce a formula whose fat content, composition and structure is more similar to human milk. ClinicalTrials.gov Identifier NCT01611649.

Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

DOE PAGES

Kučerka, Norbert; Heberle, Frederick A.; Pan, Jianjun; ...

2015-09-21

In this paper, we review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach producesmore » robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). Finally, from model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc.).« less

Tri-membrane nanoparticles produced by combining liposome fusion and a novel patchwork of bicelles to overcome endosomal and nuclear membrane barriers to cargo delivery.

PubMed

Yamada, Asako; Mitsueda, Asako; Hasan, Mahadi; Ueda, Miho; Hama, Susumu; Warashina, Shota; Nakamura, Takashi; Harashima, Hideyoshi; Kogure, Kentaro

2016-03-01

Membrane fusion is a rational strategy for crossing intracellular membranes that present barriers to liposomal nanocarrier-mediated delivery of plasmid DNA into the nucleus of non-dividing cells, such as dendritic cells. Based on this strategy, we previously developed nanocarriers consisting of a nucleic acid core particle coated with four lipid membranes [Akita, et al., Biomaterials, 2009, 30, 2940-2949]. However, including the endosomal membrane and two nuclear membranes, cells possess three intracellular membranous barriers. Thus, after entering the nucleus, nanoparticles coated with four membranes would still have one lipid membrane remaining, and could impede cargo delivery. Until now, coating a core particle with an odd number of lipid membranes was challenging. To produce nanocarriers with an odd number of lipid membranes, we developed a novel coating method involving lipid nano-discs, also known as bicelles, as a material for packaging DNA in a carrier with an odd number of lipid membranes. In this procedure, bicelles fuse to form an outer coating that resembles a patchwork quilt, which allows the preparation of nanoparticles coated with only three lipid membranes. Moreover, the transfection activity of dendritic cells with these three-membrane nanoparticles was higher than that for nanoparticles coated with four lipid membranes. In summary, we developed novel nanoparticles coated with an odd number of lipid membranes using the novel "patchwork-packaging method" to deliver plasmid DNA into the nucleus via membrane fusion.

With medium-chain triglycerides, higher and faster oxygen radical production by stimulated polymorphonuclear leukocytes occurs.

PubMed

Kruimel, J W; Naber, A H; Curfs, J H; Wenker, M A; Jansen, J B

2000-01-01

Parenteral lipid emulsions are suspected of suppressing the immune function. However, study results are contradictory and mainly concern the conventional long-chain triglyceride emulsions. Polymorphonuclear leukocytes were preincubated with parenteral lipid emulsions. The influence of the lipid emulsions on the production of oxygen radicals by these stimulated leukocytes was studied by measuring chemiluminescence. Three different parenteral lipid emulsions were tested: long-chain triglycerides, a physical mixture of medium- and long-chain triglycerides, and structured triglycerides. Structured triglycerides consist of triglycerides where the medium- and long-chain fatty acids are attached to the same glycerol molecule. Stimulated polymorphonuclear leukocytes preincubated with the physical mixture of medium- and long-chain triglycerides showed higher levels of oxygen radicals (p < .005) and faster production of oxygen radicals (p < .005) compared with polymorphonuclear leukocytes preincubated with long-chain triglycerides or structured triglycerides. Additional studies indicated that differences in results of various lipid emulsions were not caused by differences in emulsifier. The overall production of oxygen radicals was significantly lower after preincubation with the three lipid emulsions compared with controls without lipid emulsion. A physical mixture of medium- and long-chain triglycerides induced faster production of oxygen radicals, resulting in higher levels of oxygen radicals, compared with long-chain triglycerides or structured triglycerides. This can be detrimental in cases where oxygen radicals play either a pathogenic role or a beneficial one, such as when rapid phagocytosis and killing of bacteria is needed. The observed lower production of oxygen radicals by polymorphonuclear leukocytes in the presence of parenteral lipid emulsions may result in immunosuppression by these lipids.

Thermal alteration experiments on organic matter from recent marine sediments in relation to petroleum genesis

NASA Technical Reports Server (NTRS)

Ishiwatari, R.; Ishiwatari, M.; Rohrback, B. G.; Kaplan, I. R.

1977-01-01

Three fractions of organic matter: lipid (benzene:methanol-extractable), humic acid (alkali-extractable) and kerogen (residue) were extracted from a young marine sediment (Tanner Basin, offshore southern California) and heated for different times (5-116 hr) and temperatures (150-410 C). The volatile (gases) and liquid products, as well as residual material, were then analyzed. On a weight basis, the lipid fraction produced 58% of the total identified n-alkanes, the kerogen fraction 41%, and the humic acid less than 1%. The volatiles produced by heating the lipid and humic acid fractions were largely CO2 and water, whereas those produced from heated kerogen also included methane, hydrogen gas and small amounts of C2-C4 hydrocarbons. A mechanism for hydrocarbon production due to the thermal alteration of organic constituents of marine sediment is discussed.

Life-Cycle Assessment of Biodiesel Produced from Grease Trap Waste.

PubMed

Hums, Megan E; Cairncross, Richard A; Spatari, Sabrina

2016-03-01

Grease trap waste (GTW) is a low-quality waste material with variable lipid content that is an untapped resource for producing biodiesel. Compared to conventional biodiesel feedstocks, GTW requires different and additional processing steps for biodiesel production due to its heterogeneous composition, high acidity, and high sulfur content. Life-cycle assessment (LCA) is used to quantify greenhouse gas emissions, fossil energy demand, and criteria air pollutant emissions for the GTW-biodiesel process, in which the sensitivity to lipid concentration in GTW is analyzed using Monte Carlo simulation. The life-cycle environmental performance of GTW-biodiesel is compared to that of current GTW disposal, the soybean-biodiesel process, and low-sulfur diesel (LSD). The disposal of the water and solid wastes produced from separating lipids from GTW has a high contribution to the environmental impacts; however, the impacts of these processed wastes are part of the current disposal practice for GTW and could be excluded with consequential LCA system boundaries. At lipid concentrations greater than 10%, most of the environmental metrics studied are lower than those of LSD and comparable to soybean biodiesel.

Extraction of extracellular lipids from chemoautotrophic bacteria Serratia sp. ISTD04 for production of biodiesel.

PubMed

Bharti, Randhir K; Srivastava, Shaili; Thakur, Indu Shekhar

2014-08-01

A CO2 sequestering bacterial strain, Serratia sp. ISTD04, that produces a significant amount of extracellular lipids was isolated from marble mine rocks. (14)C labeling analysis revealed that the rate of assimilation of CO2 by the strain is 0.756×10(-9)μmolCO2fixedcell(-1)h(-1). It was found to produce 466mg/l of extracellular lipid which was characterized using (1)H NMR. After transesterification of lipids, the total saturated and unsaturated FAME was found to be 51% and 49% respectively. The major FAME contained in the biodiesel were palmitic acid methyl ester (C16:0), oleic acid methyl ester (C18:1) and 10-nonadecenoic acid methyl ester (C19:1). Biodiesel produced by Serratia sp. ISTD04 is balanced in terms of FAME composition of good quality. It also contained higher proportion of oleic acid (35%) which makes it suitable for utilization in existing engines. Thus, the strain can be harnessed commercially to sequester CO2 into biodiesel. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bioprospecting for hyper-lipid producing microalgal strains for sustainable biofuel production.

PubMed

Mutanda, T; Ramesh, D; Karthikeyan, S; Kumari, S; Anandraj, A; Bux, F

2011-01-01

Global petroleum reserves are shrinking at a fast pace, increasing the demand for alternate fuels. Microalgae have the ability to grow rapidly, and synthesize and accumulate large amounts (approximately 20-50% of dry weight) of neutral lipid stored in cytosolic lipid bodies. A successful and economically viable algae based biofuel industry mainly depends on the selection of appropriate algal strains. The main focus of bioprospecting for microalgae is to identify unique high lipid producing microalgae from different habitats. Indigenous species of microalgae with high lipid yields are especially valuable in the biofuel industry. Isolation, purification and identification of natural microalgal assemblages using conventional techniques is generally time consuming. However, the recent use of micromanipulation as a rapid isolating tool allows for a higher screening throughput. The appropriate media and growth conditions are also important for successful microalgal proliferation. Environmental parameters recorded at the sampling site are necessary to optimize in vitro growth. Identification of species generally requires a combination of morphological and genetic characterization. The selected microalgal strains are grown in upscale systems such as raceway ponds or photobireactors for biomass and lipid production. This paper reviews the recent methodologies adopted for site selection, sampling, strain selection and identification, optimization of cultural conditions for superior lipid yield for biofuel production. Energy generation routes of microalgal lipids and biomass are discussed in detail. Copyright © 2010 Elsevier Ltd. All rights reserved.

The Effects of Polyunsaturated Lipid Components on bilayer Structure

NASA Astrophysics Data System (ADS)

Pramudya, Y.; Kiss, A.; Nguyen, Lam T.; Yuan, J.; Hirst, Linda S.

2007-03-01

Polyunsaturated fatty acids (PUFAs), such as DHA (Docosahexanoic Acid) and AA (Alphalinoleic Acid) have been the focus of much research attention in recent years, due to their apparent health benefits and effects on cell physiology. They are found in a variety of biological membranes and have been implicated with lipid raft formation and possible function, particularly in the retinal rod cells and the central nervous system. In this work lipid bilayer structure has been investigated in lipid mixtures, incorporating polyunsaturated fatty acid moieties. The structural effects of increasing concentrations of both symmetric and asymmetric PUFA materials on the bilayer structure are investigated via synchrotron x-ray diffraction on solution samples. We observe bilayer spacings to increase with the percentage of unsaturated fatty acid lipid in the membrane, whilst the degree of ordering significantly decreases. In fact above 20% of fatty acid, well defined bilayers are no longer observed to form. Evidence of phase separation can be clearly seen from these x-ray results and in combination with AFM measurements.

Aspirin locally disrupts the liquid-ordered phase

NASA Astrophysics Data System (ADS)

Alsop, Richard J.; Himbert, Sebastian; Dhaliwal, Alexander; Schmalzl, Karin; Rheinstädter, Maikel C.

2018-02-01

Local structure and dynamics of lipid membranes play an important role in membrane function. The diffusion of small molecules, the curvature of lipids around a protein and the existence of cholesterol-rich lipid domains (rafts) are examples for the membrane to serve as a functional interface. The collective fluctuations of lipid tails, in particular, are relevant for diffusion of membrane constituents and small molecules in and across membranes, and for structure and formation of membrane domains. We studied the effect of aspirin (acetylsalicylic acid, ASA) on local structure and dynamics of membranes composed of dimyristoylphosphocholine (DMPC) and cholesterol. Aspirin is a common analgesic, but is also used in the treatment of cholesterol. Using coherent inelastic neutron scattering experiments and molecular dynamics (MD) simulations, we present evidence that ASA binds to liquid-ordered, raft-like domains and disturbs domain organization and dampens collective fluctuations. By hydrogen-bonding to lipid molecules, ASA forms `superfluid' complexes with lipid molecules that can organize laterally in superlattices and suppress cholesterol's ordering effect.

The hydrocarbon-degrading marine bacterium Cobetia sp. strain MM1IDA2H-1 produces a biosurfactant that interferes with quorum sensing of fish pathogens by signal hijacking.

PubMed

Ibacache-Quiroga, C; Ojeda, J; Espinoza-Vergara, G; Olivero, P; Cuellar, M; Dinamarca, M A

2013-07-01

Biosurfactants are produced by hydrocarbon-degrading marine bacteria in response to the presence of water-insoluble hydrocarbons. This is believed to facilitate the uptake of hydrocarbons by bacteria. However, these diffusible amphiphilic surface-active molecules are involved in several other biological functions such as microbial competition and intra- or inter-species communication. We report the isolation and characterization of a marine bacterial strain identified as Cobetia sp. MM1IDA2H-1, which can grow using the sulfur-containing heterocyclic aromatic hydrocarbon dibenzothiophene (DBT). As with DBT, when the isolated strain is grown in the presence of a microbial competitor, it produces a biosurfactant. Because the obtained biosurfactant was formed by hydroxy fatty acids and extracellular lipidic structures were observed during bacterial growth, we investigated whether the biosurfactant at its critical micelle concentration can interfere with bacterial communication systems such as quorum sensing. We focused on Aeromonas salmonicida subsp. salmonicida, a fish pathogen whose virulence relies on quorum sensing signals. Using biosensors for quorum sensing based on Chromobacterium violaceum and Vibrio anguillarum, we showed that when the purified biosurfactant was mixed with N-acyl homoserine lactones produced by A. salmonicida, quorum sensing was inhibited, although bacterial growth was not affected. In addition, the transcriptional activities of A. salmonicida virulence genes that are controlled by quorum sensing were repressed by both the purified biosurfactant and the growth in the presence of Cobetia sp. MM1IDA2H-1. We propose that the biosurfactant, or the lipid structures interact with the N-acyl homoserine lactones, inhibiting their function. This could be used as a strategy to interfere with the quorum sensing systems of bacterial fish pathogens, which represents an attractive alternative to classical antimicrobial therapies in fish aquaculture. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Characterization and Inducing Melanoma Cell Apoptosis Activity of Mannosylerythritol Lipids-A Produced from Pseudozyma aphidis

PubMed Central

Fan, Linlin; Li, Hongji; Niu, Yongwu; Chen, Qihe

2016-01-01

Mannosylerythritol lipids (MELs) are natural glycolipid biosurfactants which have potential applications in the fields of food, cosmetic and medicine. In this study, MELs were produced from vegetable oil by Pseudozyma aphidis. Their structural data through LC/MS, GC/MS and NMR analysis revealed that MEL-A with two acetyls was the major compound and the identified homologs of MEL-A contained a length of C8 to C14 fatty acid chains. This glycolipid exhibited a surface tension of 27.69 mN/m at a critical micelle concentration (CMC), self-assembling into particles in the water solution. It was observed to induce cell growth-inhibition and apoptosis of B16 melanoma cells in a dose-dependent manner, as well as cause cell cycle arrest at the S phase. Further quantitative RT-PCR analysis and western blotting revealed an increasing tendency of both mRNA and protein expressions of Caspase-12, CHOP, GRP78 and Caspase-3, and a down-regulation of protein Bcl-2. Combined with the up regulation of signaling IRE1 and ATF6, it can be speculated that MEL-A-induced B16 melanoma cell apoptosis was associated with the endoplasmic reticulum stress (ERS). PMID:26828792

Effects of green tea extract and α-tocopherol on the lipid oxidation rate of omega-3 oils, incorporated into table spreads, prepared using multiple emulsion technology.

PubMed

Dwyer, Sandra P O'; O'Beirne, David; Ní Eidhin, Deirdre; O'Kennedy, Brendan T

2012-12-01

This study examined the effectiveness of fat and water soluble antioxidants on the oxidative stability of omega (ω)-3 rich table spreads, produced using novel multiple emulsion technology. Table spreads were produced by dispersing an oil-in-water (O/W) emulsion (500 g/kg 85 camelina/15 fish oil blend) in a hardstock/rapeseed oil blend, using sodium caseinate and polyglycerol polyricinoleate as emulsifiers. The O/W and oil-in-water-in-oil (O/W/O) emulsions contained either a water soluble antioxidant (green tea extract [GTE]), an oil soluble antioxidant (α-Tocopherol), or both. Spreads containing α-Tocopherol had the highest lipid hydroperoxide values, whereas spreads containing GTE had the lowest (P < 0.05), during storage at 5°C, while p-Anisidine values did not differ significantly. Particle size was generally unaffected by antioxidant type (P < 0.05). Double emulsion (O/W/O) structures were clearly seen in confocal images of the spreads. By the end of storage, none of the spreads had significantly different G' values. Firmness (Newtons) of all spreads generally increased during storage (P < 0.05). © 2012 Institute of Food Technologists®

Effects of growth hormone on the ultrastructure of bovine preimplantation embryos.

PubMed

Kölle, Sabine; Stojkovic, Miodrag; Reese, Sven; Reichenbach, Horst-Dieter; Wolf, Eckhard; Sinowatz, Fred

2004-07-01

Growth hormone (GH) has recently been shown to promote the development of preimplantation embryos. The aim of our study was therefore to analyze the effects of GH on the morphology and ultrastructure of the cells of bovine preimplantation embryos produced by in vitro fertilization (IVF). In order to determine the physiologically optimal morphology of blastocysts, ex vivo embryos obtained by uterine flushing were also included in the study. As shown by transmission electron microscopy, treatment with GH induced the elimination of glycogen storage in cells of the inner cell mass of 7-day-old embryos. GH also stimulated the exocytosis of lipid vesicles in the inner cell mass and trophectoderm cells of these embryos. Quantitative analysis of micrographs demonstrated a higher volume density of embryonic mitochondria in 7-day-old embryos cultured with GH than in control embryos. Treatment with GH regularly resulted in an improvement of the ultrastructural features of embryos produced in vitro, thus resembling the morphology of ex vivo embryos. Scanning electron-microscopy studies demonstrated that GH altered the structure and the pore size of the zona pellucida of blastocysts. Our studies imply that GH can modulate carbohydrate, lipid, and energy metabolism and influence transportation processes in the early IVF embryo.

Genome Sequence of the Mucoromycotina Fungus Umbelopsis isabellina, an Effective Producer of Lipids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeda, Itaru; Tamano, Koichi; Yamane, Noriko

2014-02-27

Umbelopsis isabellina is a fungus in the subdivision Mucoromycotina, many members of which have been shown to be oleaginous and have become important organisms for producing oil because of their high level of intracellular lipid accumulation from various feedstocks. The genome sequence of U. isabellina NBRC 7884 was determined and annotated, and this information might provide insights into the oleaginous properties of this fungus.

Tianeptine, olanzapine and fluoxetine show similar restoring effects on stress induced molecular changes in mice brain: An FT-IR study

NASA Astrophysics Data System (ADS)

Türker-Kaya, Sevgi; Mutlu, Oğuz; Çelikyurt, İpek K.; Akar, Furuzan; Ulak, Güner

2016-05-01

Chronic stress which can cause a variety of disorders and illness ranging from metabolic and cardiovascular to mental leads to alterations in content, structure and dynamics of biomolecules in brain. The determination of stress-induced changes along with the effects of antidepressant treatment on these parameters might bring about more effective therapeutic strategies. In the present study, we investigated unpredictable chronic mild stress (UCMS)-induced changes in biomolecules in mouse brain and the restoring effects of tianeptine (TIA), olanzapine (OLZ) and fluoxetine (FLX) on these variations, by Fourier transform infrared (FT-IR) spectroscopy. The results revealed that chronic stress causes different membrane packing and an increase in lipid peroxidation, membrane fluidity. A significant increment for lipid/protein, Cdbnd O/lipid, CH3/lipid, CH2/lipid, PO-2/lipid, COO-/lipid and RNA/protein ratios but a significant decrease for lipid/protein ratios were also obtained. Additionally, altered protein secondary structure components were estimated, such as increment in random coils and beta structures. The administration of TIA, OLZ and FLX drugs restored these stress-induced variations except for alterations in protein structure and RNA/protein ratio. This may suggest that these drugs have similar restoring effects on the consequences of stress activity in brain, in spite of the differences in their action mechanisms. All findings might have importance in understanding molecular mechanisms underlying chronic stress and contribute to studies aimed for drug development.

Enhanced separation and analysis procedure reveals production of tri-acylated mannosylerythritol lipids by Pseudozyma aphidis.

PubMed

Goossens, Eliane; Wijnants, Marc; Packet, Dirk; Lemière, Filip

2016-11-01

Mannosylerythritol lipids (MELs) are one of the most promising biosurfactants because of their high fermentation yields (>100 g l -1 ) and during the last two decades they have gained a lot of attention due to their interesting self-assembling properties and biological activities. In this study, MELs were produced by fed-batch bioreactor fermentation of rapeseed oil with Pseudozyma aphidis MUCL 27852. This high-level MEL-producing yeast secretes four conventional MEL structures, -A, -B, -C and -D, which differ in their degree of acetylation. During our research, unknown compounds synthesized by P. aphidis were detected by thin-layer chromatography. The unknown compounds were separated by flash chromatography and identified as tri-acylated MELs by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The third fatty acid chain on the tri-acylated MELs was positioned on the primary alcohol of the erythritol moiety and comprised long-chain acids, mainly oleic and linoleic acid, which are not found in conventional di-acylated MELs. Furthermore, the LC-MS analysis time of conventional MELs was reduced to almost one-third by switching from HPLC-MS/MS to ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Provided optimization of the fermentation yield, P. aphidis could be an interesting novel producer of tri-acylated MELs and, thereby expand the supply and applicability of biosurfactants.

The Composition and Attributes of Colletotrichum truncatum Spores Are Altered by the Nutritional Environment

PubMed Central

Jackson, Mark A.; Schisler, David A.

1992-01-01

Previous sporulation studies with Colletotrichum truncatum NRRL 13737, a fungal pathogen of the noxious weed Sesbania exaltata, showed that the carbon-to-nitrogen (CN) ratio of the conidiation medium influenced spore yield, morphology, and efficacy in inciting disease in S. exaltata. Spores produced in a medium with a CN ratio of 10:1 were more effective than were spores produced in a 30:1 or 80:1 ratio in causing disease in S. exaltata. With a basal salts medium supplemented with glucose and Casamino Acids, substrate utilization, spore production, biomass accumulation, and biomass and spore composition were compared in submerged cultures of C. truncatum grown in media with CN ratios of 80:1, 30:1, and 10:1. All cultures were sporulating by day 2, and spore concentrations in 5-day-old cultures were significantly different: 30:1 > 10:1 > 80:1. Amino acid and glucose utilization was balanced in cultures grown in media with a CN ratio of 10:1, whereas cultures grown in media with a CN ratio of 30:1 or 80:1 depleted amino acids prior to glucose. Conidia produced in media with a CN ratio of 10:1 contained significantly more protein (32% of dry weight) and less lipid (17% of dry weight) than conidia produced in media with a CN ratio of either 30:1 (15% protein, 33% lipid) or 80:1 (12% protein, 37% lipid). The higher lipid content of spores produced in media with a CN ratio of 30:1 or 80:1 was associated with the presence of increased numbers of lipid droplets. Optimization studies on conidia produced in media with CN ratios between 30:1 and 10:1 which compared yield, attributes, and efficacy in inciting disease in S. exaltata suggest that media with a CN ratio of 15:1 to 20:1 may be optimal for conidium production. Images PMID:16348737

Structure-function relationships of new lipids designed for DNA transfection.

PubMed

Dittrich, Matthias; Heinze, Martin; Wölk, Christian; Funari, Sergio S; Dobner, Bodo; Möhwald, Helmuth; Brezesinski, Gerald

2011-08-22

Cationic liposome/DNA complexes can be used as nonviral vectors for direct delivery of DNA-based biopharmaceuticals to damaged cells and tissues. To obtain more effective and safer liposome-based gene transfection systems, two cationic lipids with identical head groups but different chain structures are investigated with respect to their in vitro gene-transfer activity, their cell-damaging characteristics, and their physicochemical properties. The gene-transfer activities of the two lipids are very different. Differential scanning calorimetry and synchrotron small- and wide-angle X-ray scattering give valuable structural insight. A subgel-like structure with high packing density and high phase-transition temperature from gel to liquid-crystalline state are found for lipid 7 (N'-2-[(2,6-diamino-1-oxohexyl)amino]ethyl-2,N-bis(hexadecyl)propanediamide) containing two saturated chains. Additionally, an ordered head-group lattice based on formation of a hydrogen-bond network is present. In contrast, lipid 8 (N'-2-[(2,6-diamino-1-oxohexyl)amino]ethyl-2-hexadecyl-N-[(9Z)-octadec-9-enyl]propanediamide) with one unsaturated and one saturated chain shows a lower phase-transition temperature and a reduced packing density. These properties enhance incorporation of the helper lipid cholesterol needed for gene transfection. Both lipids, either pure or in mixtures with cholesterol, form lamellar phases, which are preserved after addition of DNA. However, the system separates into phases containing DNA and phases without DNA. On increasing the temperature, DNA is released and only a lipid phase without intercalated DNA strands is observed. The conversion temperatures are very different in the two systems studied. The important parameter seems to be the charge density of the lipid membranes, which is a result of different solubility of cholesterol in the two lipid membranes. Therefore, different binding affinities of the DNA to the lipid mixtures are achieved. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Artificial biomembrane morphology: a dissipative particle dynamics study.

PubMed

Becton, Matthew; Averett, Rodney; Wang, Xianqiao

2017-09-18

Artificial membranes mimicking biological structures are rapidly breaking new ground in the areas of medicine and soft-matter physics. In this endeavor, we use dissipative particle dynamics simulation to investigate the morphology and behavior of lipid-based biomembranes under conditions of varied lipid density and self-interaction. Our results show that a less-than-normal initial lipid density does not create the traditional membrane; but instead results in the formation of a 'net', or at very low densities, a series of disparate 'clumps' similar to the micelles formed by lipids in nature. When the initial lipid density is high, a membrane forms, but due to the large number of lipids, the naturally formed membrane would be larger than the simulation box, leading to 'rippling' behavior as the excess repulsive force of the membrane interior overcomes the bending energy of the membrane. Once the density reaches a certain point however, 'bubbles' appear inside the membrane, reducing the rippling behavior and eventually generating a relatively flat, but thick, structure with micelles of water inside the membrane itself. Our simulations also demonstrate that the interaction parameter between individual lipids plays a significant role in the formation and behavior of lipid membrane assemblies, creating similar structures as the initial lipid density distribution. This work provides a comprehensive approach to the intricacies of lipid membranes, and offers a guideline to design biological or polymeric membranes through self-assembly processes as well as develop novel cellular manipulation and destruction techniques.

Enzymatic synthesis of capric acid-rich structured lipids (MUM type) using Candida antarctica lipase.

PubMed

SilRoy, Sumita; Ghosh, Mahua

2011-01-01

The objective of the work was to produce capric acid rich structured lipids starting from various Indian indigenous vegetable oils, such as rice bran, ground nut and mustard oils. Acidolysis reaction between individual vegetable oils and capric acid in one is to three molar ratios at 45 degree centigrade temperature was carried out using position specific Candida antarctica lipase so as to protect the Sn-2 position of the oils which are rich in unsaturated fatty acids. The incorporation of capric acid depended on the reaction time showing 6 % within 6 h and 30.8 % in 72 h with rice bran oil. Similarly, in ground nut oil incorporation of capric acid was 34.2 % in 72 h compared to 5.3 % in 6 h. Thus mustard oil showed much lower incorporation than the other two oils, with 3.3 % and 19.5 % in 6 and 72 h respectively. The incorporation of capric acid was influenced by the nature of the fatty acids present in the original oil. The fatty acid composition of Sn-2 position of the structured triacylglycerols of the three oils revealed that capric acid was mainly replacing the fatty acids occupying the Sn-1 and 3 positions of the triglyceride molecule.

Selective synthesis of human milk fat-style structured triglycerides from microalgal oil in a microfluidic reactor packed with immobilized lipase

DOE PAGES

Wang, Jun; Liu, Xi; Wang, Xu -Dong; ...

2016-08-18

Human milk fat-style structured triacylglycerols were produced from microalgal oil in a continuous microfluidic reactor packed with immobilized lipase for the first time. A remarkably high conversion efficiency was demonstrated in the microreactor with reaction time being reduced by 8 times, Michaelis constant decreased 10 times, the lipase reuse times increased 2.25-fold compared to those in a batch reactor. In addition, the content of palmitic acid at sn-2 position (89.0%) and polyunsaturated fatty acids at sn-1, 3 positions (81.3%) are slightly improved compared to the product in a batch reactor. The increase of melting points (1.7 °C) and decrease ofmore » crystallizing point (3 °C) implied higher quality product was produced using the microfluidic technology. The main cost can be reduced from 212.3 to 14.6 per batch with the microreactor. Altogether, the microfluidic bioconversion technology is promising for modified functional lipids production allowing for cost-effective approach to produce high-value microalgal coproducts.« less

Selective synthesis of human milk fat-style structured triglycerides from microalgal oil in a microfluidic reactor packed with immobilized lipase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jun; Liu, Xi; Wang, Xu -Dong

Human milk fat-style structured triacylglycerols were produced from microalgal oil in a continuous microfluidic reactor packed with immobilized lipase for the first time. A remarkably high conversion efficiency was demonstrated in the microreactor with reaction time being reduced by 8 times, Michaelis constant decreased 10 times, the lipase reuse times increased 2.25-fold compared to those in a batch reactor. In addition, the content of palmitic acid at sn-2 position (89.0%) and polyunsaturated fatty acids at sn-1, 3 positions (81.3%) are slightly improved compared to the product in a batch reactor. The increase of melting points (1.7 °C) and decrease ofmore » crystallizing point (3 °C) implied higher quality product was produced using the microfluidic technology. The main cost can be reduced from 212.3 to 14.6 per batch with the microreactor. Altogether, the microfluidic bioconversion technology is promising for modified functional lipids production allowing for cost-effective approach to produce high-value microalgal coproducts.« less

Production of novel types of antibacterial liamocins by diverse strains of Aureobasidium pullulans grown on different culture media.

PubMed

Leathers, Timothy D; Price, Neil P J; Bischoff, Kenneth M; Manitchotpisit, Pennapa; Skory, Christopher D

2015-10-01

To compare production of antibacterial liamocins (polyol lipids) by diverse strains of Aureobasidium pullulans grown on different culture media. Liamocins produced by strains of A. pullulans have potential agricultural and pharmaceutical applications as antibacterials with specificity against Streptococcus spp. Six strains of A. pullulans were characterized for liamocin production on four different culture media. The choice of strain and culture medium affected growth, liamocin yields, and production of contaminating pigments. Best growth and highest liamocin yields were obtained using A. pullulans strain NRRL 50384 grown on a sucrose basal medium. Unexpectedly, the choice of strain and culture medium also affected the structure of liamocins produced, providing novel types of liamocins. Liamocins varied not only in the ratios of trimer and tetramer polyester tail groups, but also in the nature of the polyol headgroup, which could include mannitol, arabitol, or glycerol. The ability to conveniently produce novel types of liamocins in good yields will provide novel antibacterials for applied uses, and facilitate structure-function studies on the mechanism of antibacterial activity.

Selective synthesis of human milk fat-style structured triglycerides from microalgal oil in a microfluidic reactor packed with immobilized lipase.

PubMed

Wang, Jun; Liu, Xi; Wang, Xu-Dong; Dong, Tao; Zhao, Xing-Yu; Zhu, Dan; Mei, Yi-Yuan; Wu, Guo-Hua

2016-11-01

Human milk fat-style structured triacylglycerols were produced from microalgal oil in a continuous microfluidic reactor packed with immobilized lipase for the first time. A remarkably high conversion efficiency was demonstrated in the microreactor with reaction time being reduced by 8 times, Michaelis constant decreased 10 times, the lipase reuse times increased 2.25-fold compared to those in a batch reactor. In addition, the content of palmitic acid at sn-2 position (89.0%) and polyunsaturated fatty acids at sn-1, 3 positions (81.3%) are slightly improved compared to the product in a batch reactor. The increase of melting points (1.7°C) and decrease of crystallizing point (3°C) implied higher quality product was produced using the microfluidic technology. The main cost can be reduced from $212.3 to $14.6 per batch with the microreactor. Overall, the microfluidic bioconversion technology is promising for modified functional lipids production allowing for cost-effective approach to produce high-value microalgal coproducts. Copyright © 2016 Elsevier Ltd. All rights reserved.

Carbon nanotubes for stabilization of nanostructured lipid particles

NASA Astrophysics Data System (ADS)

Gaunt, Nicholas P.; Patil-Sen, Yogita; Baker, Matthew J.; Kulkarni, Chandrashekhar V.

2014-12-01

Carbon nanotubes (CNTs) are increasingly studied for innovative biotechnological applications particularly where they are combined with essential biological materials like lipids. Lipids have been used earlier for enhancing the dispersibility of CNTs in aqueous solutions. Here we report a novel application of CNTs for stabilization of internally self-assembled nanostructured lipid particles of 2-5 μm size. Single-walled (pristine) as well as -OH and -COOH functionalized multi-walled CNTs were employed to produce nanostructured emulsions which stayed stable for months and could be re-dispersed after complete dehydration. Concentrations of CNTs employed for stabilization were very low; moreover CNTs were well-decorated with lipid molecules. These features contribute towards reducing their toxicity and improving biocompatibility for biomedical and pharmaceutical applications. Our approach paves the way for future development of combination therapies employing both CNTs and nanostructured lipid self-assembly together as carriers of different drugs.Carbon nanotubes (CNTs) are increasingly studied for innovative biotechnological applications particularly where they are combined with essential biological materials like lipids. Lipids have been used earlier for enhancing the dispersibility of CNTs in aqueous solutions. Here we report a novel application of CNTs for stabilization of internally self-assembled nanostructured lipid particles of 2-5 μm size. Single-walled (pristine) as well as -OH and -COOH functionalized multi-walled CNTs were employed to produce nanostructured emulsions which stayed stable for months and could be re-dispersed after complete dehydration. Concentrations of CNTs employed for stabilization were very low; moreover CNTs were well-decorated with lipid molecules. These features contribute towards reducing their toxicity and improving biocompatibility for biomedical and pharmaceutical applications. Our approach paves the way for future development of combination therapies employing both CNTs and nanostructured lipid self-assembly together as carriers of different drugs. Electronic supplementary information (ESI) available: Concentration series studies with Raman spectroscopy and small angle X-ray diffraction pattern for dry lipid and dehydrated CNT-lipid particles support the article. See DOI: 10.1039/c4nr05593d

The Search for a Lipid Trigger: The Effect of Salt Stress on the Lipid Profile of the Model Microalgal Species Chlamydomonas reinhardtii for Biofuels Production.

PubMed

Hounslow, Emily; Kapoore, Rahul Vijay; Vaidyanathan, Seetharaman; Gilmour, D James; Wright, Phillip C

2016-11-01

Algal cells produce neutral lipid when stressed and this can be used to generate biodiesel. Salt stressed cells of the model microalgal species Chlamydomonas reinhardtii were tested for their suitability to produce lipid for biodiesel. The starchless mutant of C. reinhardtii (CC-4325) was subjected to salt stress (0.1, 0.2 and 0.3 M NaCl) and transesterification and GC analysis were used to determine fatty acid methyl ester (FAME) content and profile. Fatty acid profile was found to vary under salt stress conditions, with a clear distinction between 0.1 M NaCl, which the algae could tolerate, and the higher levels of NaCl (0.2 and 0.3 M), which caused cell death. Lipid content was increased under salt conditions, either through long-term exposure to 0.1 M NaCl, or short-term exposure to 0.2 and 0.3 M NaCl. Palmitic acid (C16:0) and linolenic acid (C18:3n3) were found to increase significantly at the higher salinities. Salt increase can act as a lipid trigger for C. reinhardtii.

Bioactive lipids in the butter production chain from Parmigiano Reggiano cheese area.

PubMed

Verardo, Vito; Gómez-Caravaca, Ana M; Gori, Alessandro; Losi, Giuseppe; Caboni, Maria F

2013-11-01

Bovine milk contains hundreds of diverse components, including proteins, peptides, amino acids, lipids, lactose, vitamins and minerals. Specifically, the lipid composition is influenced by different variables such as breed, feed and technological process. In this study the fatty acid and phospholipid compositions of different samples of butter and its by-products from the Parmigiano Reggiano cheese area, produced by industrial and traditional churning processes, were determined. The fatty acid composition of samples manufactured by the traditional method showed higher levels of monounsaturated and polyunsaturated fatty acids compared with industrial samples. In particular, the contents of n-3 fatty acids and conjugated linoleic acids were higher in samples produced by the traditional method than in samples produced industrially. Sample phospholipid composition also varied between the two technological processes. Phosphatidylethanolamine was the major phospholipid in cream, butter and buttermilk samples obtained by the industrial process as well as in cream and buttermilk samples from the traditional process, while phosphatidylcholine was the major phospholipid in traditionally produced butter. This result may be explained by the different churning processes causing different types of membrane disruption. Generally, samples produced traditionally had higher contents of total phospholipids; in particular, butter produced by the traditional method had a total phospholipid content 33% higher than that of industrially produced butter. The samples studied represent the two types of products present in the Parmigiano Reggiano cheese area, where the industrial churning process is widespread compared with the traditional processing of Reggiana cow's milk. This is because Reggiana cow's milk production is lower than that of other breeds and the traditional churning process is time-consuming and economically disadvantageous. However, its products have been demonstrated to contain more bioactive lipids compared with products obtained from other breeds and by the industrial process. © 2013 Society of Chemical Industry.

Contactless Stimulation and Control of Biomimetic Nanotubes by Calcium Ion Gradients.

PubMed

Kirejev, Vladimir; Ali Doosti, Baharan; Shaali, Mehrnaz; Jeffries, Gavin D M; Lobovkina, Tatsiana

2018-04-17

Membrane tubular structures are important communication pathways between cells and cellular compartments. Studying these structures in their native environment is challenging, due to the complexity of membranes and varying chemical conditions within and outside of the cells. This work demonstrates that a calcium ion gradient, applied to a synthetic lipid nanotube, triggers lipid flow directed toward the application site, resulting in the formation of a bulge aggregate. This bulge can be translated in a contactless manner by moving a calcium ion source along the lipid nanotube. Furthermore, entrapment of polystyrene nanobeads within the bulge does not tamper the bulge movement and allows transporting of the nanoparticle cargo along the lipid nanotube. In addition to the synthetic lipid nanotubes, the response of cell plasma membrane tethers to local calcium ion stimulation is investigated. The directed membrane transport in these tethers is observed, but with slower kinetics in comparison to the synthetic lipid nanotubes. The findings of this work demonstrate a novel and contactless mode of transport in lipid nanotubes, guided by local exposure to calcium ions. The observed lipid nanotube behavior can advance the current understanding of the cell membrane tubular structures, which are constantly reshaped during dynamic cellular processes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cell-sized asymmetric lipid vesicles facilitate the investigation of asymmetric membranes

NASA Astrophysics Data System (ADS)

Kamiya, Koki; Kawano, Ryuji; Osaki, Toshihisa; Akiyoshi, Kazunari; Takeuchi, Shoji

2016-09-01

Asymmetric lipid giant vesicles have been used to model the biochemical reactions in cell membranes. However, methods for producing asymmetric giant vesicles lead to the inclusion of an organic solvent layer that affects the mechanical and physical characteristics of the membrane. Here we describe the formation of asymmetric giant vesicles that include little organic solvent, and use them to investigate the dynamic responses of lipid molecules in the vesicle membrane. We formed the giant vesicles via the inhomogeneous break-up of a lipid microtube generated by applying a jet flow to an asymmetric planar lipid bilayer. The asymmetric giant vesicles showed a lipid flip-flop behaviour in the membrane, superficially similar to the lipid flip-flop activity observed in apoptotic cells. In vitro synthesis of membrane proteins into the asymmetric giant vesicles revealed that the lipid asymmetry in bilayer membranes improves the reconstitution ratio of membrane proteins. Our asymmetric giant vesicles will be useful in elucidating lipid-lipid and lipid-membrane protein interactions involved in the regulation of cellular functions.

Neuronal Lipid Metabolism: Multiple Pathways Driving Functional Outcomes in Health and Disease

PubMed Central

Tracey, Timothy J.; Steyn, Frederik J.; Wolvetang, Ernst J.; Ngo, Shyuan T.

2018-01-01

Lipids are a fundamental class of organic molecules implicated in a wide range of biological processes related to their structural diversity, and based on this can be broadly classified into five categories; fatty acids, triacylglycerols (TAGs), phospholipids, sterol lipids and sphingolipids. Different lipid classes play major roles in neuronal cell populations; they can be used as energy substrates, act as building blocks for cellular structural machinery, serve as bioactive molecules, or a combination of each. In amyotrophic lateral sclerosis (ALS), dysfunctions in lipid metabolism and function have been identified as potential drivers of pathogenesis. In particular, aberrant lipid metabolism is proposed to underlie denervation of neuromuscular junctions, mitochondrial dysfunction, excitotoxicity, impaired neuronal transport, cytoskeletal defects, inflammation and reduced neurotransmitter release. Here we review current knowledge of the roles of lipid metabolism and function in the CNS and discuss how modulating these pathways may offer novel therapeutic options for treating ALS. PMID:29410613

Binding Site and Potency Prediction of Teixobactin and other Lipid II Ligands by Statistical Base Scoring of Conformational Space Maps.

PubMed

Lungu, Claudiu N; Diudea, Mircea V

2018-01-01

Lipid II, a peptidoglycan, is a precursor in bacterial cell synthesis. It has both hydrophilic and lipophilic properties. The molecule translocates a bacterial membrane to deliver and incorporate "building blocks" from disaccharide-pentapeptide into the peptidoglican wall. Lipid II is a valid antibiotic target. A receptor binding pocket may be occupied by a ligand in various plausible conformations, among which only few ones are energetically related to a biological activity in the physiological efficiency domain. This paper reports the mapping of the conformational space of Lipid II in its interaction with Teixobactin and other Lipid II ligands. In order to study computationally the complex between Lipid II and ligands, a docking study was first carried on. Docking site was retrieved form literature. After docking, 5 ligand conformations and further 5 complexes (denoted 00 to 04) for each molecule were taken into account. For each structure, conformational studies were performed. Statistical analysis, conformational analysis and molecular dynamics based clustering were used to predict the potency of these compounds. A score for potency prediction was developed. Appling lipid II classification according to Lipid II conformational energy, a conformation of Teixobactin proved to be energetically favorable, followed by Oritravicin, Dalbavycin, Telvanicin, Teicoplamin and Vancomycin, respectively. Scoring of molecules according to cluster band and PCA produced the same result. Molecules classified according to standard deviations showed Dalbavycin as the most favorable conformation, followed by Teicoplamin, Telvanicin, Teixobactin, Oritravicin and Vancomycin, respectively. Total score showing best energetic efficiency of complex formation shows Teixobactin to have the best conformation (a score of 15 points) followed by Dalbavycin (14 points), Oritravicin (12v points), Telvanicin (10 points), Teicoplamin (9 points), Vancomycin (3 points). Statistical analysis of conformations can be used to predict the efficiency of ligand - target interaction and consecutively to find insight regarding ligand potency and postulate about favorable conformation of ligand and binding site. In this study it was shown that Teixobactin is more efficient in binding with Lipid II compared to Vancomycin, results confirmed by experimental data reported in literature. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Lipids, lysosomes, and autophagy

PubMed Central

2016-01-01

Lipids are essential components of a cell providing energy substrates for cellular processes, signaling intermediates, and building blocks for biological membranes. Lipids are constantly recycled and redistributed within a cell. Lysosomes play an important role in this recycling process that involves the recruitment of lipids to lysosomes via autophagy or endocytosis for their degradation by lysosomal hydrolases. The catabolites produced are redistributed to various cellular compartments to support basic cellular function. Several studies demonstrated a bidirectional relationship between lipids and lysosomes that regulate autophagy. While lysosomal degradation pathways regulate cellular lipid metabolism, lipids also regulate lysosome function and autophagy. In this review, we focus on this bidirectional relationship in the context of dietary lipids and provide an overview of recent evidence of how lipid-overload lipotoxicity, as observed in obesity and metabolic syndrome, impairs lysosomal function and autophagy that may eventually lead to cellular dysfunction or cell death. PMID:27330054

Recombinant production and solution structure of lipid transfer protein from lentil Lens culinaris

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gizatullina, Albina K.; Moscow Institute of Physics and Technology; Finkina, Ekaterina I.

2013-10-04

Highlights: •Lipid transfer protein from lentil seeds (Lc-LTP2) was overexpressed in E. coli. •Antimicrobial activity and spatial structure of the recombinant Lc-LTP2 were examined. •Internal tunnel-like lipid-binding cavity occupies ∼7% of the total Lc-LTP2 volume. •Binding of DMPG lipid induces moderate rearrangements in the Lc-LTP2 structure. •Lc-LTP2/DMPG complex has limited lifetime and dissociates within tens of hours. -- Abstract: Lipid transfer protein, designated as Lc-LTP2, was isolated from seeds of the lentil Lens culinaris. The protein has molecular mass 9282.7 Da, consists of 93 amino acid residues including 8 cysteines forming 4 disulfide bonds. Lc-LTP2 and its stable isotope labeledmore » analogues were overexpressed in Escherichia coli and purified. Antimicrobial activity of the recombinant protein was examined, and its spatial structure was studied by NMR spectroscopy. The polypeptide chain of Lc-LTP2 forms four α-helices (Cys4-Leu18, Pro26-Ala37, Thr42-Ala56, Thr64-Lys73) and a long C-terminal tail without regular secondary structure. Side chains of the hydrophobic residues form a relatively large internal tunnel-like lipid-binding cavity (van der Waals volume comes up to ∼600 Å{sup 3}). The side-chains of Arg45, Pro79, and Tyr80 are located near an assumed mouth of the cavity. Titration with dimyristoyl phosphatidylglycerol (DMPG) revealed formation of the Lc-LTP2/lipid non-covalent complex accompanied by rearrangements in the protein spatial structure and expansion of the internal cavity. The resultant Lc-LTP2/DMPG complex demonstrates limited lifetime and dissociates within tens of hours.« less

Metabolism of nC11 fatty acid fed to Trichoderma koningii and Penicillium janthinellum II: Production of intracellular and extracellular lipids.

PubMed

Monreal, Carlos M; Chahal, Amarpreet; Rowland, Owen; Smith, Myron; Schnitzer, Morris

2014-01-01

Little is known about the fungal metabolism of nC10 and nC11 fatty acids and their conversion into lipids. A mixed batch culture of soil fungi, T. koningii and P. janthinellum, was grown on undecanoic acid (UDA), a mixture of UDA and potato dextrose broth (UDA+PDB), and PDB alone to examine their metabolic conversion during growth. We quantified seven intracellular and extracellular lipid classes using Iatroscan thin-layer chromatography with flame ionization detection (TLC-FID). Gas chromatography with flame ionization detection (GC-FID) was used to quantify 42 individual fatty acids. Per 150 mL culture, the mixed fungal culture grown on UDA+PDB produced the highest amount of intracellular (531 mg) and extracellular (14.7 mg) lipids during the exponential phase. The content of total intracellular lipids represented 25% of the total biomass-carbon, or 10% of the total biomass dry weight produced. Fatty acids made up the largest class of intracellular lipids (457 mg/150 mL culture) and they were synthesized at a rate of 2.4 mg/h during the exponential phase, and decomposed at a rate of 1.8 mg/h during the stationary phase, when UDA+PDB was the carbon source. Palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and vaccenic acid (C18:1) accounted for >80% of the total intracellular fatty acids. During exponential growth on UDA+PDB, hydrocarbons were the largest pool of all extracellular lipids (6.5 mg), and intracellularly they were synthesized at a rate of 64 μg/h. The mixed fungal species culture of T. koningii and P. janthinellum produced many lipids for potential use as industrial feedstocks or bioproducts in biorefineries.

A comparison of the lung clearance kinetics of solid lipid nanoparticles and liposomes by following the 3H-labelled structural lipids after pulmonary delivery in rats.

PubMed

Haque, Shadabul; Whittaker, Michael; McIntosh, Michelle P; Pouton, Colin W; Phipps, Simon; Kaminskas, Lisa M

2018-04-01

The utility of biodegradable nanosized drug carriers for the local and controlled delivery of therapeutics to the lungs has prompted significant interest in the development of inhalable nanomedicines. Still, little is known about how these systems are cleared from the lungs, including the kinetics of the structural lipids. Most preclinical and clinical studies to date have evaluated the lung clearance of loaded drugs, which in many cases poorly reflects the kinetics of the nanocarrier, or the bulk-labelled particles. This study therefore aimed to describe and compare the pulmonary pharmacokinetic behaviour and patterns of lung clearance of two commonly explored inhalable nanocarriers (anionic ∼150 nm liposomes and solid lipid nanoparticles [SLNs]) in rats by following the 3 H-labelled structural lipids (phosphatidylcholine and tristearin respectively). The data showed that SLNs and liposomes were cleared from the lungs at similar rates, despite SLNs being deposited after intratracheal instillation in the upper respiratory track, and primarily via the mucociliary escalator, but this process was more pronounced for SLNs. Structural lipids were mainly associated with plasma proteins rather than nanocarrier in plasma. The lipids also exhibit prolonged lung exposure and are associated with the lung tissue (rather than BALF) over 2 weeks. Copyright © 2018 Elsevier B.V. All rights reserved.

Labellar anatomy and secretion in Bulbophyllum Thouars (Orchidaceae: Bulbophyllinae) sect. Racemosae Benth. & Hook. f.

PubMed Central

Davies, Kevin L.; Stpiczyńska, Malgorzata

2014-01-01

Background and Aims Floral secretions are common in Bulbophyllum Thouars, and the labella of a number of Asian species are said to produce secretions rich in lipids that act as food rewards for insect pollinators. Although some of these reports are based on simple histochemical tests, a much greater number are anecdotal and, hitherto, neither the ultrastructure of the labellum nor the secretory process has been investigated in detail. Furthermore, sophisticated histochemical approaches have generally not been applied. Here, both the labellar structure and the secretory process are investigated for four species of Asian Bulbophyllum sect. Racemosae Benth. & Hook. f., namely Bulbophyllum careyanum (Hook.) Spreng., B. morphologorum Kraenzl., B. orientale Seidenf. and B. wangkaense Seidenf., and compared with those of unequivocal lipid-secreting orchids. Methods Labellar, secretory tissue was investigated using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. Key Results The adaxial median longitudinal groove of the labellum contained secretory tissue comprising palisade-like epidermal cells, similar to those of certain lipid-secreting Oncidiinae Benth. However, these cells and their secretions gave positive results mainly for protein and mucilage, and their organelle complement was consistent with that of cells involved in protein and mucilage synthesis. Sub-cuticular accumulation of secretion resulted in cuticular distension and blistering. The sub-epidermal layer of isodiametric parenchyma contained starch and, like the epidermal cells, ultrastructure consistent with mucilage synthesis. Lipids were mainly confined to the cuticle, and hardly any intracellular lipid droplets were observed. Conclusions It is proposed that mucilage is produced by dictyosomes present in the palisade-like epidermal cells. Mucilage precursors may also be produced by these same organelles in sub-epidermal cells and are thought to pass along the symplast via plasmodesmata into the adjoining palisade-like secretory cells, which contain abundant arrays of rough endoplasmic reticulum. Here, they become chemically modified and form a protein-rich, mucilaginous secretion that, following vesicle-mediated transport across the cytoplasm, traverses the cell wall and accumulates in blisters formed from the distended cuticle. Rupture of these blisters releases the secretion onto the labellar surface. However, in certain species, there is some evidence that the secretion may traverse the cuticle via cuticular pores, and micro-channels may permit the passage of fragrance. Hydrolysis of sub-epidermal starch probably generates the carbohydrate and, together with mitochondria, much of the energy required for the secretory process. This anatomical organization resembles that found in certain lipid-secreting, Neotropical species of Bulbophyllum and Oncidiinae, but since the chemical composition of their secretions is different, and these taxa occur on a separate continent and have different insect pollinators, parallelism of floral anatomy is likely. PMID:25122654

Surfactant protein B: lipid interactions of synthetic peptides representing the amino-terminal amphipathic domain.

PubMed Central

Bruni, R; Taeusch, H W; Waring, A J

1991-01-01

The mechanisms by which pulmonary surfactant protein B (SP-B) affects the surface activity of surfactant lipids are unclear. We have studied the peptide/lipid interactions of the amino-terminal amphipathic domain of SP-B by comparing the secondary conformations and surface activities of a family of synthetic peptides based on the native human SP-B sequence, modified by site-specific amino acid substitutions. Circular dichroism measurements show an alpha-helical structure correlating with the ability of the peptides to interact with lipids and with the surface activity of peptide/lipid dispersions. Amino acid substitutions altering either the charge or the hydrophobicity of the residues lowered the helical content and reduced the association of the aminoterminal segment with lipid dispersions. Surface activity of peptide/lipid mixtures was maximally altered by reversal of charge in synthetic peptides. These observations indicate that electrostatic interactions and hydrophobicity are important factors in determining optimal structure and function of surfactant peptides in lipid dispersions. Images PMID:1871144

Computer simulation studies on passive recruitment dynamics of lipids induced by the adsorption of charged nanoparticles.

PubMed

Li, Yang

2014-07-07

The recruitment dynamics of lipids in the biomembrane is believed to play an important role in a variety of cellular processes. In this work, we investigate the nanoparticle-induced recruitment dynamics of lipids in the heterogeneous phospholipid bilayers of distearoyl-phosphatidylcholine (DSPC) and dioleoyl-phosphatidylglycerol (DOPG) via coarse-grained molecular dynamics simulations. Three dynamic modes of individual charged DOPG lipid molecules have been taken into account in the recruitment process: lateral diffusion, protrusions, and flip-flops. Based on analysis of the mobility pattern of lipids, structural variations in the membrane as well as activation energy of the structure of lipid eyelids characterized by the potential of mean force, we have concluded that the electrostatic attraction of nanoparticles plays a crucial role in the recruitment process of lipids in phospholipid bilayers. These studies are consistent with experimental observations and to some extent give insight into the origin of some cellular processes such as signaling, formation of lipid rafts, and endocytosis.

Differential Interaction of Antimicrobial Peptides with Lipid Structures Studied by Coarse-Grained Molecular Dynamics Simulations.

PubMed

Balatti, Galo E; Ambroggio, Ernesto E; Fidelio, Gerardo D; Martini, M Florencia; Pickholz, Mónica

2017-10-20

In this work; we investigated the differential interaction of amphiphilic antimicrobial peptides with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid structures by means of extensive molecular dynamics simulations. By using a coarse-grained (CG) model within the MARTINI force field; we simulated the peptide-lipid system from three different initial configurations: (a) peptides in water in the presence of a pre-equilibrated lipid bilayer; (b) peptides inside the hydrophobic core of the membrane; and (c) random configurations that allow self-assembled molecular structures. This last approach allowed us to sample the structural space of the systems and consider cooperative effects. The peptides used in our simulations are aurein 1.2 and maculatin 1.1; two well-known antimicrobial peptides from the Australian tree frogs; and molecules that present different membrane-perturbing behaviors. Our results showed differential behaviors for each type of peptide seen in a different organization that could guide a molecular interpretation of the experimental data. While both peptides are capable of forming membrane aggregates; the aurein 1.2 ones have a pore-like structure and exhibit a higher level of organization than those conformed by maculatin 1.1. Furthermore; maculatin 1.1 has a strong tendency to form clusters and induce curvature at low peptide-lipid ratios. The exploration of the possible lipid-peptide structures; as the one carried out here; could be a good tool for recognizing specific configurations that should be further studied with more sophisticated methodologies.

UV Lamp as a Facile Ozone Source for Structural Analysis of Unsaturated Lipids Via Electrospray Ionization-Mass Spectrometry.

PubMed

Stinson, Craig A; Zhang, Wenpeng; Xia, Yu

2018-03-01

Ozonolysis of alkene functional groups is a type of highly specific and effective chemical reaction, which has found increasing applications in structural analysis of unsaturated lipids via coupling with mass spectrometry (MS). In this work, we utilized a low-pressure mercury lamp (6 W) to initiate ozonolysis inside electrospray ionization (ESI) sources. By placing the lamp near a nanoESI emitter that partially transmits 185 nm ultraviolet (UV) emission from the lamp, dissolved dioxygen in the spray solution was converted into ozone, which subsequently cleaved the double bonds within fatty acyls of lipids. Solvent conditions, such as presence of water and acid solution pH, were found to be critical in optimizing ozonolysis yields. Fast (on seconds time scale) and efficient (50%-100% yield) ozonolysis was achieved for model unsaturated phospholipids and fatty acids with UV lamp-induced ozonolysis incorporated on a static and an infusion nanoESI source. The method was able to differentiate double bond location isomers and identify the geometry of the double bond based on yield. The analytical utility of UV lamp-induced ozonolysis was further demonstrated by implementation on a liquid chromatography (LC)-MS platform. Ozonolysis was effected in a flow microreactor that was made from ozone permeable tubing, so that ambient ozone produced by the lamp irradiation could diffuse into the reactor and induce online ozonolysis post-LC separation and before ESI-MS. Graphical Abstract ᅟ.

UV Lamp as a Facile Ozone Source for Structural Analysis of Unsaturated Lipids Via Electrospray Ionization-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Stinson, Craig A.; Zhang, Wenpeng; Xia, Yu

2018-03-01

Ozonolysis of alkene functional groups is a type of highly specific and effective chemical reaction, which has found increasing applications in structural analysis of unsaturated lipids via coupling with mass spectrometry (MS). In this work, we utilized a low-pressure mercury lamp (6 W) to initiate ozonolysis inside electrospray ionization (ESI) sources. By placing the lamp near a nanoESI emitter that partially transmits 185 nm ultraviolet (UV) emission from the lamp, dissolved dioxygen in the spray solution was converted into ozone, which subsequently cleaved the double bonds within fatty acyls of lipids. Solvent conditions, such as presence of water and acid solution pH, were found to be critical in optimizing ozonolysis yields. Fast (on seconds time scale) and efficient (50%-100% yield) ozonolysis was achieved for model unsaturated phospholipids and fatty acids with UV lamp-induced ozonolysis incorporated on a static and an infusion nanoESI source. The method was able to differentiate double bond location isomers and identify the geometry of the double bond based on yield. The analytical utility of UV lamp-induced ozonolysis was further demonstrated by implementation on a liquid chromatography (LC)-MS platform. Ozonolysis was effected in a flow microreactor that was made from ozone permeable tubing, so that ambient ozone produced by the lamp irradiation could diffuse into the reactor and induce online ozonolysis post-LC separation and before ESI-MS. [Figure not available: see fulltext.

Detailed Dimethylacetal and Fatty Acid Composition of Rumen Content from Lambs Fed Lucerne or Concentrate Supplemented with Soybean Oil

PubMed Central

Alves, Susana P.; Santos-Silva, José; Cabrita, Ana R. J.; Fonseca, António J. M.; Bessa, Rui J. B.

2013-01-01

Lipid metabolism in the rumen is responsible for the complex fatty acid profile of rumen outflow compared with the dietary fatty acid composition, contributing to the lipid profile of ruminant products. A method for the detailed dimethylacetal and fatty acid analysis of rumen contents was developed and applied to rumen content collected from lambs fed lucerne or concentrate based diets supplemented with soybean oil. The methodological approach developed consisted on a basic/acid direct transesterification followed by thin-layer chromatography to isolate fatty acid methyl esters from dimethylacetal, oxo- fatty acid and fatty acid dimethylesters. The dimethylacetal composition was quite similar to the fatty acid composition, presenting even-, odd- and branched-chain structures. Total and individual odd- and branched-chain dimethylacetals were mostly affected by basal diet. The presence of 18∶1 dimethylacetals indicates that biohydrogenation intermediates might be incorporated in structural microbial lipids. Moreover, medium-chain fatty acid dimethylesters were identified for the first time in the rumen content despite their concentration being relatively low. The fatty acids containing 18 carbon-chain lengths comprise the majority of the fatty acids present in the rumen content, most of them being biohydrogenation intermediates of 18∶2n−6 and 18∶3n−3. Additionally, three oxo- fatty acids were identified in rumen samples, and 16-O-18∶0 might be produced during biohydrogenation of the 18∶3n−3. PMID:23484024

Molecular dynamics simulation of the evolution of hydrophobic defects in one monolayer of a phosphatidylcholine bilayer: relevance for membrane fusion mechanisms.

PubMed Central

Tieleman, D Peter; Bentz, Joe

2002-01-01

The spontaneous formation of the phospholipid bilayer underlies the permeability barrier function of the biological membrane. Tears or defects that expose water to the acyl chains are spontaneously healed by lipid lateral diffusion. However, mechanical barriers, e.g., protein aggregates held in place, could sustain hydrophobic defects. Such defects have been postulated to occur in processes such as membrane fusion. This gives rise to a new question in bilayer structure: What do the lipids do in the absence of lipid lateral diffusion to minimize the free energy of a hydrophobic defect? As a first step to understand this rather fundamental question about bilayer structure, we performed molecular dynamic simulations of up to 10 ns of a planar bilayer from which lipids have been deleted randomly from one monolayer. In one set of simulations, approximately one-half of the lipids in the defect monolayer were restrained to form a mechanical barrier. In the second set, lipids were free to diffuse around. The question was simply whether the defects caused by removing a lipid would aggregate together, forming a large hydrophobic cavity, or whether the membrane would adjust in another way. When there are no mechanical barriers, the lipids in the defect monolayer simply spread out and thin with little effect on the other intact monolayer. In the presence of a mechanical barrier, the behavior of the lipids depends on the size of the defect. When 3 of 64 lipids are removed, the remaining lipids adjust the lower one-half of their chains, but the headgroup structure changes little and the intact monolayer is unaffected. When 6 to 12 lipids are removed, the defect monolayer thins, lipid disorder increases, and lipids from the intact monolayer move toward the defect monolayer. Whereas this is a highly simplified model of a fusion site, this engagement of the intact monolayer into the fusion defect is strikingly consistent with recent results for influenza hemagglutinin mediated fusion. PMID:12202375

Silicon supported lipid-DNA thin film structures at varying temperature studied by energy dispersive X-ray diffraction and neutron reflectivity.

PubMed

Domenici, F; Castellano, C; Dell'Unto, F; Albinati, A; Congiu, A

2011-11-01

Non-viral gene transfection by means of lipid-based nanosystems, such as solid supported lipid assemblies, is often limited due to their lack of stability and the consequent loss of efficiency. Therefore not only a detailed thermo-lyotropic study of these DNA-lipid complexes is necessary to understand their interaction mechanisms, but it can also be considered as a first step in conceiving and developing new transfection biosystems. The aim of our study is a structural characterization of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC)-dimethyl-dioctadecyl-ammonium bromide (DDAB)-DNA complex at varying temperature using the energy dispersive X-ray diffraction (EDXD) and neutron reflectivity (NR) techniques. We have shown the formation of a novel thermo-lyotropic structure of DOPC/DDAB thin film self-organized in multi-lamellar planes on (100)-oriented silicon support by spin coating, thus enlightening its ability to include DNA strands. Our NR measurements indicate that the DOPC/DDAB/DNA complex forms temperature-dependent structures. At 65°C and relative humidity of 100% DNA fragments are buried between single lamellar leaflets constituting the hydrocarbon core of the lipid bilayers. This finding supports the consistency of the hydrophobic interaction model, which implies that the coupling between lipid tails and hypo-hydrated DNA single strands could be the driving force of DNA-lipid complexation. Upon cooling to 25°C, EDXD analysis points out that full-hydrated DOPC-DDAB-DNA can switch in a different metastable complex supposed to be driven by lipid heads-DNA electrostatic interaction. Thermotropic response analysis also clarifies that DOPC has a pivotal role in promoting the formation of our observed thermophylic silicon supported lipids-DNA assembly. Copyright © 2011 Elsevier B.V. All rights reserved.

Lipid nanoparticles for administration of poorly water soluble neuroactive drugs.

PubMed

Esposito, Elisabetta; Drechsler, Markus; Mariani, Paolo; Carducci, Federica; Servadio, Michela; Melancia, Francesca; Ratano, Patrizia; Campolongo, Patrizia; Trezza, Viviana; Cortesi, Rita; Nastruzzi, Claudio

2017-09-01

This study describes the potential of solid lipid nanoparticles and nanostructured lipid carriers as nano-formulations to administer to the central nervous system poorly water soluble drugs. Different neuroactive drugs, i.e. dimethylfumarate, retinyl palmitate, progesterone and the endocannabinoid hydrolysis inhibitor URB597 have been studied. Lipid nanoparticles constituted of tristearin or tristearin in association with gliceryl monoolein were produced. The nanoencapsulation strategy allowed to obtain biocompatible and non-toxic vehicles, able to increase the solubility of the considered neuroactive drugs. To improve URB597 targeting to the brain, stealth nanoparticles were produced modifying the SLN surface with polysorbate 80. A behavioural study was conducted in rats to test the ability of SLN containing URB597 given by intranasal administration to alter behaviours relevant to psychiatric disorders. URB597 maintained its activity after nanoencapsulation, suggesting the possibility to propose this kind of vehicle as alternative to unphysiological mixtures usually employed for animal and clinical studies.

Microalgae-mediated simultaneous treatment of toxic thiocyanate and production of biodiesel.

PubMed

Ryu, Byung-Gon; Kim, Jungmin; Yoo, Gursong; Lim, Jun-Taek; Kim, Woong; Han, Jong-In; Yang, Ji-Won

2014-04-01

In this work, a method for simultaneously degrading the toxic pollutant, thiocyanate, and producing microalgal lipids using mixed microbial communities was developed. Aerobic activated sludge was used as the seed culture and thiocyanate was used as the sole nitrogen source. Two cultivation methods were sequentially employed: a lithoautotrophic mode and a photoautotrophic mode. Thiocyanate hydrolysis and a nitrification was found to occur under the first (lithoautotrophic) condition, while the oxidized forms of nitrogen were assimilated by the photoautotrophic consortium and lipids were produced under the second condition. The final culture exhibited good settling efficiency (∼ 70% settling over 10 min), which can benefit downstream processing. The highest CO2 fixation rate and lipid productivity were observed with 2.5% and 5% CO2, respectively. The proposed integrated algal-bacterial system appears to be a feasible and even beneficial option for thiocyanate treatment and production of microbial lipids. Copyright © 2014 Elsevier Ltd. All rights reserved.

High-throughput methods for electron crystallography.

PubMed

Stokes, David L; Ubarretxena-Belandia, Iban; Gonen, Tamir; Engel, Andreas

2013-01-01

Membrane proteins play a tremendously important role in cell physiology and serve as a target for an increasing number of drugs. Structural information is key to understanding their function and for developing new strategies for combating disease. However, the complex physical chemistry associated with membrane proteins has made them more difficult to study than their soluble cousins. Electron crystallography has historically been a successful method for solving membrane protein structures and has the advantage of providing a native lipid environment for these proteins. Specifically, when membrane proteins form two-dimensional arrays within a lipid bilayer, electron microscopy can be used to collect images and diffraction and the corresponding data can be combined to produce a three-dimensional reconstruction, which under favorable conditions can extend to atomic resolution. Like X-ray crystallography, the quality of the structures are very much dependent on the order and size of the crystals. However, unlike X-ray crystallography, high-throughput methods for screening crystallization trials for electron crystallography are not in general use. In this chapter, we describe two alternative methods for high-throughput screening of membrane protein crystallization within the lipid bilayer. The first method relies on the conventional use of dialysis for removing detergent and thus reconstituting the bilayer; an array of dialysis wells in the standard 96-well format allows the use of a liquid-handling robot and greatly increases throughput. The second method relies on titration of cyclodextrin as a chelating agent for detergent; a specialized pipetting robot has been designed not only to add cyclodextrin in a systematic way, but to use light scattering to monitor the reconstitution process. In addition, the use of liquid-handling robots for making negatively stained grids and methods for automatically imaging samples in the electron microscope are described.

Lipid monolayer structure and interactions in the presence of peptides and proteins

NASA Astrophysics Data System (ADS)

Freites, Juan Alfredo

Structural aspects of two simple model systems, protein-lipid monolayer and peptide-lipid monolayer, were studied by experimental and computer simulation techniques. In both cases, both the choice of system and the approach employed to studying it, were motivated by specific biological problems. The interaction of annexin A1 with monolayers of dipalmitoylphosphatidylcholine (DPPC) was studied by fluorescence microscopy as a function of lipid monolayer phase and pH. It was shown that the annexin A1-DPPC interaction depends strongly on both the domain structure and phase behavior of the DPPC monolayer, and only weakly on the subphase pH. Annexin A1 was found to be line-active, adsorbing preferentially at phase boundaries. Also, annexin A1 was found to form networks in the presence of a domain structure in the lipid monolayer. Molecular dynamics simulations were carried out on a model system composed of a surfactant protein B peptide, SP-B1--25, and a monolayer of hexadecanoic acid. A detailed structural characterization was performed as a function of the lipid monolayer specic area. It was found that the peptide remains inserted in the monolayer up to values of specific area corresponding to an untilted condensed phase of the pure hexadecanoic acid monolayer. The system remains stable by altering the conformational order of both the anionic lipid monolayer and the peptide secondary structure, and effectively constitutes a unique disordered lipid-peptide monolayer phase. Two elements appear to be key for the constitution of this phase: an electrostatic interaction between the cationic residues of the peptide with the anionic headgroups of the lipids, and an exclusion of the aromatic residues on the hydrophobic end of the peptide from the hydrophilic and aqueous regions of the system. A direct comparison between molecular dynamics simulations and laboratory experiments was performed for hexadecanoic acid monolayer systems. In order to simulate specific points on the surface pressure vs. area isotherm, an algorithm for the control of surface pressure was developed based on previous work by Martyna, Tobias and Klein. The algorithm was implemented and tested with the hexadecanoic acid monolayer system.

Structural elucidation of the interaction between neurodegenerative disease-related tau protein with model lipid membranes

NASA Astrophysics Data System (ADS)

Jones, Emmalee M.

A protein's sequence of amino acids determines how it folds. That folded structure is linked to protein function, and misfolding to dysfunction. Protein misfolding and aggregation into beta-sheet rich fibrillar aggregates is connected with over 20 neurodegenerative diseases, including Alzheimer's disease (AD). AD is characterized in part by misfolding, aggregation and deposition of the microtubule associated tau protein into neurofibrillary tangles (NFTs). However, two questions remain: What is tau's fibrillization mechanism, and what is tau's cytotoxicity mechanism? Tau is prone to heterogeneous interactions, including with lipid membranes. Lipids have been found in NFTs, anionic lipid vesicles induced aggregation of the microtubule binding domain of tau, and other protein aggregates induced ion permeability in cells. This evidence prompted our investigation of tau's interaction with model lipid membranes to elucidate the structural perturbations those interactions induced in tau protein and in the membrane. We show that although tau is highly charged and soluble, it is highly surface active and preferentially interacts with anionic membranes. To resolve molecular-scale structural details of tau and model membranes, we utilized X-ray and neutron scattering techniques. X-ray reflectivity indicated tau aggregated at air/water and anionic lipid membrane interfaces and penetrated into membranes. More significantly, membrane interfaces induced tau protein to partially adopt a more compact conformation with density similar to folded protein and ordered structure characteristic of beta-sheet formation. This suggests possible membrane-based mechanisms of tau aggregation. Membrane morphological changes were seen using fluorescence microscopy, and X-ray scattering techniques showed tau completely disrupts anionic membranes, suggesting an aggregate-based cytotoxicity mechanism. Further investigation of protein constructs and a "hyperphosphorylation" disease mimic helped clarify the role of the microtubule binding domain in anionic lipid affinity and demonstrated even "hyperphosphorylation" did not prevent interaction with anionic membranes. Additional studies investigated more complex membrane models to increase physiological relevance. These insights revealed structural changes in tau protein and lipid membranes after interaction. We observed tau's affinity for interfaces, and aggregation and compaction once tau partitions to interfaces. We observed the beginnings of beta-sheet formation in tau at anionic lipid membranes. We also examined disruption to the membrane on a molecular scale.

Detection of superlattice domain formation in ternary lipid mixtures using fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Mutlu, Burcin; Lopez, Stephanie; Vaughn, Mark; Huang, Juyang; Cheng, K.

2011-10-01

Multicomponent lipid bilayers represent an important model system for studying the structures and functions of cell membranes. At present, the lateral organization of lipid components, particularly the formation of regular distribution, in lipid membranes containing charged lipid, e.g., phosphatidylserine, is not clear. Using a ternary phosphatidylcholine/phosphatidylserine/cholesterol lipid bilayer system, the presence of ordered domain formation was examined by measuring the fluorescence anisotropy of the embedded fluorescent probe, 22-(N-(7-nitrobenz-2-oxa-1,3-diazol- 4-yl)amino)-23,24-bisnor-5-cholen-3β- ol (NBD-CHOL), with structure similar to that of a cholesterol, as a function of phospatidylserine composition. The plot of the anisotropy vs. phosphatidylserine revealed abrupt changes at certain critical compositions of phosphatidylserine. Some of these critical compositions agree favorably with those predicted by the headgroup superlattice model suggesting that the charged phosphatidylserine lipid molecules adopt a superlattice-like distribution in the lipid bilayer at some predicted compositions. The ordered distribution of charged lipids may play an important role in the regulation of the composition of the biological membranes.

Optimization of Chlorella vulgaris and bioflocculant-producing bacteria co-culture: enhancing microalgae harvesting and lipid content.

PubMed

Wang, Y; Yang, Y; Ma, F; Xuan, L; Xu, Y; Huo, H; Zhou, D; Dong, S

2015-05-01

Microalgae are a sustainable bioresource, and the biofuel they produce is widely considered to be an alternative to limited natural fuel resources. However, microalgae harvesting is a bottleneck in the development of technology. Axenic Chlorella vulgaris microalgae exhibit poor harvesting, as expressed by a flocculation efficiency of 0·2%. This work optimized the co-culture conditions of C. vulgaris and bioflocculant-producing bacteria in synthetic wastewater using response surface methodology (RSM), thus aiming to enhance C. vulgaris harvesting and lipid content. Three significant process variables- inoculation ratio of bacteria and microalgae, initial glucose concentration, and co-culture time- were proposed in the RSM model. F-values (3·98/8·46) and R(2) values (0·7817/0·8711) both indicated a reasonable prediction by the RSM model. The results showed that C. vulgaris harvesting efficiency reached 45·0-50·0%, and the lipid content was over 21·0% when co-cultured with bioflocculant-producing bacteria under the optimized culture conditions of inoculation ratio of bacteria and microalgae of 0·20-0·25, initial glucose concentration of <1·5 kg m(-3) and co-culture time of 9-14 days. This work provided new insights into microalgae harvesting and cost-effective microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production. This work optimized the co-culture conditions of microalgae (C. vulgaris) and bioflocculant-producing bacteria (F2, Rhizobium radiobacter) in synthetic wastewater using response surface methodology, aiming to enhance C. vulgaris harvesting and lipid produced content. Bioflocculant-producing microbes are environmentally friendly functional materials. They avoid the negative effects of traditional chemical flocculants. This work provided new insights into microalgae harvesting and cost-effective production of microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production. © 2015 The Society for Applied Microbiology.

Effects of mesquite gum-candelilla wax based edible coatings on the quality of guava fruit (Psidium guajava L.)

NASA Astrophysics Data System (ADS)

Tomás, S. A.; Bosquez-Molina, E.; Stolik, S.; Sánchez, F.

2005-06-01

The ability of composite edible coatings to preserve the quality of guava fruit (Psidium guajava L.) at 20ºC was studied for a period of 15 days. The edible coatings were formulated with candelilla wax blended with white mineral oil as the lipid phase and mesquite gum as the structural material. The use of edible coatings prolonged the shelf life of treated fruits by retarding ethylene emission and enhancing texture as compared to control samples. At the sixth day, the ethylene produced by the control samples was fivefold higher than the ethylene produced by the coated samples. In addition, the physiological weight loss of coated fruits was nearly 30% lower than the control samples.

Synthetic lipids and their role in defining macromolecular assemblies.

PubMed

Parrill, Abby L

2015-10-01

Lipids have a variety of physiological roles, ranging from structural and biophysical contributions to membrane functions to signaling contributions in normal and abnormal physiology. This review highlights some of the contributions made by Robert Bittman to our understanding of lipid assemblies through the production of synthetic lipid analogs in the sterol, sphingolipid, and glycolipid classes. His contributions have included the development of a fluorescent cholesterol analog that shows strong functional analogies to cholesterol that has allowed live imaging of cholesterol distribution in living systems, to stereospecific synthetic approaches to both sphingolipid and glycolipid analogs crucial in defining the structure-activity relationships of lipid biological targets. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Structure, inhibition, and regulation of essential lipid A enzymes.

PubMed

Zhou, Pei; Zhao, Jinshi

2017-11-01

The Raetz pathway of lipid A biosynthesis plays a vital role in the survival and fitness of Gram-negative bacteria. Research efforts in the past three decades have identified individual enzymes of the pathway and have provided a mechanistic understanding of the action and regulation of these enzymes at the molecular level. This article reviews the discovery, biochemical and structural characterization, and regulation of the essential lipid A enzymes, as well as continued efforts to develop novel antibiotics against Gram-negative pathogens by targeting lipid A biosynthesis. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016 Elsevier B.V. All rights reserved.

Synergistic interactions of lipids and myelin basic protein

NASA Astrophysics Data System (ADS)

Hu, Yufang; Doudevski, Ivo; Wood, Denise; Moscarello, Mario; Husted, Cynthia; Genain, Claude; Zasadzinski, Joseph A.; Israelachvili, Jacob

2004-09-01

This report describes force measurements and atomic force microscope imaging of lipid-protein interactions that determine the structure of a model membrane system that closely mimics the myelin sheath. Our results suggest that noncovalent, mainly electrostatic and hydrophobic, interactions are responsible for the multilamellar structure and stability of myelin. We find that myelin basic protein acts as a lipid coupler between two apposed bilayers and as a lipid "hole-filler," effectively preventing defect holes from developing. From our protein-mediated-adhesion and force-distance measurements, we develop a simple quantitative model that gives a reasonably accurate picture of the molecular mechanism and adhesion of bilayer-bridging proteins by means of noncovalent interactions. The results and model indicate that optimum myelin adhesion and stability depend on the difference between, rather than the product of, the opposite charges on the lipid bilayers and myelin basic protein, as well as on the repulsive forces associated with membrane fluidity, and that small changes in any of these parameters away from the synergistically optimum values can lead to large changes in the adhesion or even its total elimination. Our results also show that the often-asked question of which membrane species, the lipids or the proteins, are the "important ones" may be misplaced. Both components work synergistically to provide the adhesion and overall structure. A better appreciation of the mechanism of this synergy may allow for a better understanding of stacked and especially myelin membrane structures and may lead to better treatments for demyelinating diseases such as multiple sclerosis. lipid-protein interactions | myelin membrane structure | membrane adhesion | membrane regeneration/healing | demyelinating diseases

Self-assembled stable sponge-type nanocarries for Brucea javanica oil delivery.

PubMed

Zou, Aihua; Li, Yawen; Chen, Yiyin; Angelova, Angelina; Garamus, Vasil M; Li, Na; Drechsler, Markus; Angelov, Borislav; Gong, Yabin

2017-05-01

Sponge-type nanocarriers (spongosomes) are produced upon dispersion of a liquid crystalline sponge phase formed by self-assembly of an amphiphilic lipid in excess aqueous phase. The inner organization of the spongosomes is built-up by randomly ordered bicontinuous lipid membranes and their surfaces are stabilized by alginate chains providing stealth properties and colloidal stability. The present study elaborates spongosomes for improved encapsulation of Brucea javanica oil (BJO), a traditional Chinese medicine that may strongly inhibit proliferation and metastasis of various cancers. The inner structural organization and the morphology characteristics of BJO-loaded nanocarriers at varying quantities of BJO were determined by cryogenic transmission electron microscopy (Cryo-TEM), small angle X-ray scattering (SAXS) and dynamic light scattering (DLS). Additionally, the drug loading and drug release profiles for BJO-loaded spongosome systems also were determined. We found that the sponge-type liquid crystalline lipid membrane organization provides encapsulation efficiency rate of BJO as high as 90%. In vitro cytotoxicity and apoptosis study of BJO spongosome nanoparticles with A549 cells demonstrated enhanced anti-tumor efficiency. These results suggest potential clinical applications of the obtained safe spongosome formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Toward an Animal Model of the Human Tear Film: Biochemical Comparison of the Mouse, Canine, Rabbit, and Human Meibomian Lipidomes

PubMed Central

Butovich, Igor A.; Lu, Hua; McMahon, Anne; Eule, J. Corinna

2012-01-01

Purpose. Secretions that are produced by meibomian glands (also known as meibum) are a major source of lipids for the ocular surface of humans and animals alike. Many animal species have been evaluated for their meibomian lipidomes. However, there have been a very small number of studies in which the animals were compared with humans side by side. Therefore, the purpose of this study was to compare meibum collected from humans and three typical laboratory animals, canines, mice, and rabbits, for their meibomian lipid composition in order to determine which animal species most resembles humans. Methods. High pressure liquid chromatography (HPLC) and gas-liquid chromatography (GLC) in combination with mass spectrometry were used to evaluate lipidomes of all tested species. Results. Among three tested animal species, mice were found to be the closest match to humans in terms of their meibomian lipidomes, while canines were the second closest species. The lipids of these three species were close to each other structurally and, for most lipid classes, quantitatively. The rabbit meibomian lipidome, on the other hand, was vastly different from lipidomes of all other tested species. Interestingly, a previously described class of lipids, acylated omega-hydroxy fatty acids (OAHFA), was found to be present in every tested species as the major amphiphilic component of meibum. Conclusions. Our side by side comparison of the rabbit and the human meibum demonstrated their vast differences. Thus, the rabbit seems to be a poor animal model of the human tear film, at least when studying its biochemistry and biophysics. PMID:22918629

Advances in structural and functional analysis of membrane proteins by electron crystallography

PubMed Central

Wisedchaisri, Goragot; Reichow, Steve L.; Gonen, Tamir

2011-01-01

Summary Electron crystallography is a powerful technique for the study of membrane protein structure and function in the lipid environment. When well-ordered two-dimensional crystals are obtained the structure of both protein and lipid can be determined and lipid-protein interactions analyzed. Protons and ionic charges can be visualized by electron crystallography and the protein of interest can be captured for structural analysis in a variety of physiologically distinct states. This review highlights the strengths of electron crystallography and the momentum that is building up in automation and the development of high throughput tools and methods for structural and functional analysis of membrane proteins by electron crystallography. PMID:22000511

Advances in structural and functional analysis of membrane proteins by electron crystallography.

PubMed

Wisedchaisri, Goragot; Reichow, Steve L; Gonen, Tamir

2011-10-12

Electron crystallography is a powerful technique for the study of membrane protein structure and function in the lipid environment. When well-ordered two-dimensional crystals are obtained the structure of both protein and lipid can be determined and lipid-protein interactions analyzed. Protons and ionic charges can be visualized by electron crystallography and the protein of interest can be captured for structural analysis in a variety of physiologically distinct states. This review highlights the strengths of electron crystallography and the momentum that is building up in automation and the development of high throughput tools and methods for structural and functional analysis of membrane proteins by electron crystallography. Copyright © 2011 Elsevier Ltd. All rights reserved.

Maximally asymmetric transbilayer distribution of anionic lipids alters the structure and interaction with lipids of an amyloidogenic protein dimer bound to the membrane surface.

PubMed

Cheng, Sara Y; Chou, George; Buie, Creighton; Vaughn, Mark W; Compton, Campbell; Cheng, Kwan H

2016-03-01

We used molecular dynamics simulations to explore the effects of asymmetric transbilayer distribution of anionic phosphatidylserine (PS) lipids on the structure of a protein on the membrane surface and subsequent protein-lipid interactions. Our simulation systems consisted of an amyloidogenic, beta-sheet rich dimeric protein (D42) absorbed to the phosphatidylcholine (PC) leaflet, or protein-contact PC leaflet, of two membrane systems: a single-component PC bilayer and double PC/PS bilayers. The latter comprised of a stable but asymmetric transbilayer distribution of PS in the presence of counterions, with a 1-component PC leaflet coupled to a 1-component PS leaflet in each bilayer. The maximally asymmetric PC/PS bilayer had a non-zero transmembrane potential (TMP) difference and higher lipid order packing, whereas the symmetric PC bilayer had a zero TMP difference and lower lipid order packing under physiologically relevant conditions. Analysis of the adsorbed protein structures revealed weaker protein binding, more folding in the N-terminal domain, more aggregation of the N- and C-terminal domains and larger tilt angle of D42 on the PC leaflet surface of the PC/PS bilayer versus the PC bilayer. Also, analysis of protein-induced membrane structural disruption revealed more localized bilayer thinning in the PC/PS versus PC bilayer. Although the electric field profile in the non-protein-contact PS leaflet of the PC/PS bilayer differed significantly from that in the non-protein-contact PC leaflet of the PC bilayer, no significant difference in the electric field profile in the protein-contact PC leaflet of either bilayer was evident. We speculate that lipid packing has a larger effect on the surface adsorbed protein structure than the electric field for a maximally asymmetric PC/PS bilayer. Our results support the mechanism that the higher lipid packing in a lipid leaflet promotes stronger protein-protein but weaker protein-lipid interactions for a dimeric protein on membrane surfaces. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Proteomic analysis of lipid body from the alkenone‐producing marine haptophyte alga Tisochrysis lutea

PubMed Central

Shi, Qing; Araie, Hiroya; Bakku, Ranjith Kumar; Fukao, Yoichiro; Rakwal, Randeep; Suzuki, Iwane

2015-01-01

Lipid body (LB) is recognized as the cellular carbon and energy storage organelle in many organisms. LBs have been observed in the marine haptophyte alga Tisochrysis lutea that produces special lipids such as long‐chain (C37‐C40) ketones (alkenones) with 2–4 trans‐type double bonds. In this study, we succeeded in developing a modified method to isolate LB from T. lutea. Purity of isolated LBs was confirmed by the absence of chlorophyll auto‐fluorescence and no contamination of the most abundant cellular protein ribulose‐1,5‐bisphosphate carboxylase/oxygenase. As alkenones predominated in the LB by GC‐MS analysis, the LB can be more appropriately named as “alkenone body (AB).” Extracted AB‐containing proteins were analyzed by the combination of 1DE (SDS‐PAGE) and MS/MS for confident protein identification and annotated using BLAST tools at National Center for Biotechnology Information. Totally 514 proteins were identified at the maximum. The homology search identified three major proteins, V‐ATPase, a hypothetical protein EMIHUDRAFT_465517 found in other alkenone‐producing haptophytes, and a lipid raft‐associated SPFH domain‐containing protein. Our data suggest that AB of T. lutera is surrounded by a lipid membrane originating from either the ER or the ER‐derived four layer‐envelopes chloroplast and function as the storage site of alkenones and alkenes. PMID:25914246

Functional analysis of lipid metabolism genes in wine yeasts during alcoholic fermentation at low temperature

PubMed Central

López-Malo, María; García-Ríos, Estéfani; Chiva, Rosana; Guillamon, José M.

2014-01-01

Wine produced by low-temperature fermentation is mostly considered to have improved sensory qualities. However few commercial wine strains available on the market are well-adapted to ferment at low temperature (10 - 15°C). The lipid metabolism of Saccharomyces cerevisiae plays a central role in low temperature adaptation. One strategy to modify lipid composition is to alter transcriptional activity by deleting or overexpressing the key genes of lipid metabolism. In a previous study, we identified the genes of the phospholipid, sterol and sphingolipid pathways, which impacted on growth capacity at low temperature. In the present study, we aimed to determine the influence of these genes on fermentation performance and growth during low-temperature wine fermentations. We analyzed the phenotype during fermentation at the low and optimal temperature of the lipid mutant and overexpressing strains in the background of a derivative commercial wine strain. The increase in the gene dosage of some of these lipid genes, e.g., PSD1, LCB3, DPL1 and OLE1, improved fermentation activity during low-temperature fermentations, thus confirming their positive role during wine yeast adaptation to cold. Genes whose overexpression improved fermentation activity at 12°C were overexpressed by chromosomal integration into commercial wine yeast QA23. Fermentations in synthetic and natural grape must were carried out by this new set of overexpressing strains. The strains overexpressing OLE1 and DPL1 were able to finish fermentation before commercial wine yeast QA23. Only the OLE1 gene overexpression produced a specific aroma profile in the wines produced with natural grape must. PMID:28357215

Functional analysis of lipid metabolism genes in wine yeasts during alcoholic fermentation at low temperature.

PubMed

López-Malo, María; García-Ríos, Estéfani; Chiva, Rosana; Guillamon, José M

2014-10-29

Wine produced by low-temperature fermentation is mostly considered to have improved sensory qualities. However few commercial wine strains available on the market are well-adapted to ferment at low temperature (10 - 15°C). The lipid metabolism of Saccharomyces cerevisiae plays a central role in low temperature adaptation. One strategy to modify lipid composition is to alter transcriptional activity by deleting or overexpressing the key genes of lipid metabolism. In a previous study, we identified the genes of the phospholipid, sterol and sphingolipid pathways, which impacted on growth capacity at low temperature. In the present study, we aimed to determine the influence of these genes on fermentation performance and growth during low-temperature wine fermentations. We analyzed the phenotype during fermentation at the low and optimal temperature of the lipid mutant and overexpressing strains in the background of a derivative commercial wine strain. The increase in the gene dosage of some of these lipid genes, e.g., PSD1 , LCB3, DPL1 and OLE1, improved fermentation activity during low-temperature fermentations, thus confirming their positive role during wine yeast adaptation to cold. Genes whose overexpression improved fermentation activity at 12°C were overexpressed by chromosomal integration into commercial wine yeast QA23. Fermentations in synthetic and natural grape must were carried out by this new set of overexpressing strains. The strains overexpressing OLE1 and DPL1 were able to finish fermentation before commercial wine yeast QA23. Only the OLE1 gene overexpression produced a specific aroma profile in the wines produced with natural grape must.

Structural aspects of digestion of medium chain triglycerides studied in real time using sSAXS and Cryo-TEM.

PubMed

Phan, Stephanie; Hawley, Adrian; Mulet, Xavier; Waddington, Lynne; Prestidge, Clive A; Boyd, Ben J

2013-12-01

The purpose of this study was to investigate the colloidal structures formed on digestion of medium chain triglyceride (MCT) with a specific objective of identifying and characterizing a previously reported vesicular phase, which has been linked to supersaturation and anomalous digestion kinetics, and to evaluate the influence of lipid mass and enzyme inhibition on self assembled structure. MCT was digested in vitro and nanostructure was monitored in real time using synchrotron small angle X-ray scattering (sSAXS), and morphology was studied using cryogenic transmission electron microscopy (cryo-TEM). Formation of the putative vesicular phase formed on digestion of MCT was confirmed and its structural attributes were determined. Vesicle formation was dependent on lipid mass and bile salt concentration. The use of enzyme inhibitor for offline analysis of lipolysis samples did influence structural aspects of the digestion medium when compared to real time evaluation. The formation of a vesicular phase was directly linked to the kinetics of lipid digestion. Vesicle formation is linked to lipid mass, or more specifically the ratio of lipid to bile salts present in the digestion mixture. Inhibition of lipase to halt digestion during sampling for offline analysis must be done with caution as structural aspects were shown to differ for the MCT digests with and without inhibitor present.

Formation of mannitol core microparticles for sustained release with lipid coating in a mini fluid bed system.

PubMed

Wang, Bifeng; Friess, Wolfgang

2017-11-01

The goal of this study was to prepare sustained release microparticles for methyl blue and aspartame as sparingly and freely water-soluble model drugs by lipid film coating in a Mini-Glatt fluid bed, and to assess the effect of coating load of two of lipids, hard fat and glyceryl stearate, on the release rates. 30g drug-loaded mannitol carrier microparticles with average diameter of 500 or 300μm were coated with 5g, 10g, 20g and 30g lipids, respectively. The model drugs were completely released in vitro through pores which mainly resulted from dissolution of the polyol core beads. The release of methyl blue from microparticles based on 500μm carrier beads extended up to 25days, while aspartame release from microparticles formed from 300μm carrier beads was extended to 7days. Although glyceryl stearate exhibits higher wettability, burst and release rates were similar for the two lipid materials. Polymorphic transformation of the hart fat was observed upon release. The lipid-coated microparticles produced with 500μm carrier beads showed slightly lower burst release compared to the microparticles produced with 300μm carrier beads as they carried relatively thicker lipid layer based on an equivalent lipid to mannitol ratio. Aspartame microparticles showed a much faster release than methyl blue due to the higher water-solubility of aspartame. Copyright © 2017 Elsevier B.V. All rights reserved.

Origin of β-Carotene-Rich Plastoglobuli in Dunaliella bardawil1[C][W][OPEN

PubMed Central

Davidi, Lital; Shimoni, Eyal; Khozin-Goldberg, Inna; Zamir, Ada; Pick, Uri

2014-01-01

The halotolerant microalgae Dunaliella bardawil accumulates under nitrogen deprivation two types of lipid droplets: plastoglobuli rich in β-carotene (βC-plastoglobuli) and cytoplasmatic lipid droplets (CLDs). We describe the isolation, composition, and origin of these lipid droplets. Plastoglobuli contain β-carotene, phytoene, and galactolipids missing in CLDs. The two preparations contain different lipid-associated proteins: major lipid droplet protein in CLD and the Prorich carotene globule protein in βC-plastoglobuli. The compositions of triglyceride (TAG) molecular species, total fatty acids, and sn-1+3 and sn-2 positions in the two lipid pools are similar, except for a small increase in palmitic acid in plastoglobuli, suggesting a common origin. The formation of CLD TAG precedes that of βC-plastoglobuli, reaching a maximum after 48 h of nitrogen deprivation and then decreasing. Palmitic acid incorporation kinetics indicated that, at early stages of nitrogen deprivation, CLD TAG is synthesized mostly from newly formed fatty acids, whereas in βC-plastoglobuli, a large part of TAG is produced from fatty acids of preformed membrane lipids. Electron microscopic analyses revealed that CLDs adhere to chloroplast envelope membranes concomitant with appearance of small βC-plastoglobuli within the chloroplast. Based on these results, we propose that CLDs in D. bardawil are produced in the endoplasmatic reticulum, whereas βC-plastoglobuli are made, in part, from hydrolysis of chloroplast membrane lipids and in part, by a continual transfer of TAG or fatty acids derived from CLD. PMID:24567188

Formation of Stable Cationic Lipid/DNA Complexes for Gene Transfer

NASA Astrophysics Data System (ADS)

Hofland, Hans E. J.; Shephard, Lee; Sullivan, Sean M.

1996-07-01

Stable cationic lipid/DNA complexes were formed by solubilizing cationic liposomes with 1% octylglucoside and complexing a DNA plasmid with the lipid in the presence of detergent. Removal of the detergent by dialysis yielded a lipid/DNA suspension that was able to transfect tissue culture cells up to 90 days after formation with no loss in activity. Similar levels of gene transfer were obtained by mixing the cationic lipid in a liposome form with DNA just prior to cell addition. However, expression was completely lost 24 hr after mixing. The transfection efficiency of the stable complex in 15% fetal calf serum was 30% of that obtained in the absence of serum, whereas the transient complex was completely inactivated with 2% fetal calf serum. A 90-day stability study comparing various storage conditions showed that the stable complex could be stored frozen or as a suspension at 4 degrees C with no loss in transfection efficiency. Centrifugation of the stable complex produced a pellet that contained approximately 90% of the DNA and 10% of the lipid. Transfection of cells with the resuspended pellet and the supernatant showed that the majority of the transfection activity was in the pellet and all the toxicity was in the supernatant. Formation of a stable cationic lipid/DNA complex has produced a transfection vehicle that can be stored indefinitely, can be concentrated with no loss in transfection efficiency, and the toxicity levels can be greatly reduced when the active complex is isolated from the uncomplexed lipid.

Effects of Lipid Composition on Bilayer Membranes Quantified by All-Atom Molecular Dynamics.

PubMed

Ding, Wei; Palaiokostas, Michail; Wang, Wen; Orsi, Mario

2015-12-10

Biological bilayer membranes typically contain varying amounts of lamellar and nonlamellar lipids. Lamellar lipids, such as dioleoylphosphatidylcholine (DOPC), are defined by their tendency to form the lamellar phase, ubiquitous in biology. Nonlamellar lipids, such as dioleoylphosphatidylethanolamine (DOPE), prefer instead to form nonlamellar phases, which are mostly nonbiological. However, nonlamellar lipids mix with lamellar lipids in biomembrane structures that remain overall lamellar. Importantly, changes in the lamellar vs nonlamellar lipid composition are believed to affect membrane function and modulate membrane proteins. In this work, we employ atomistic molecular dynamics simulations to quantify how a range of bilayer properties are altered by variations in the lamellar vs nonlamellar lipid composition. Specifically, we simulate five DOPC/DOPE bilayers at mixing ratios of 1/0, 3/1, 1/1, 1/3, and 0/1. We examine properties including lipid area and bilayer thickness, as well as the transmembrane profiles of electron density, lateral pressure, electric field, and dipole potential. While the bilayer structure is only marginally altered by lipid composition changes, dramatic effects are observed for the lateral pressure, electric field, and dipole potential profiles. Possible implications for membrane function are discussed.

Alkyl ether lipids, ion channels and lipid raft reorganization in cancer therapy.

PubMed

Jaffrès, Paul-Alain; Gajate, Consuelo; Bouchet, Ana Maria; Couthon-Gourvès, Hélène; Chantôme, Aurélie; Potier-Cartereau, Marie; Besson, Pierre; Bougnoux, Philippe; Mollinedo, Faustino; Vandier, Christophe

2016-09-01

Synthetic alkyl lipids, such as the ether lipids edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) and ohmline (1-O-hexadecyl-2-O-methyl-rac-glycero-3-β-lactose), are forming a class of antitumor agents that target cell membranes to induce apoptosis and to decrease cell migration/invasion, leading to the inhibition of tumor and metastasis development. In this review, we present the structure-activity relationship of edelfosine and ohmline, and we point out differences and similarities between these two amphiphilic compounds. We also discuss the mechanisms of action of these synthetic alkyl ether lipids (involving, among other structures and molecules, membrane domains, Fas/CD95 death receptor signaling, and ion channels), and highlight a key role for lipid rafts in the underlying process. The reorganization of lipid raft membrane domains induced by these alkyl lipids affects the function of death receptors and ion channels, thus leading to apoptosis and/or inhibition of cancer cell migration. The possible therapeutic use of these alkyl lipids and the clinical perspectives for these lipids in prevention or/and treatment of tumor development and metastasis are also discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

Single Cell Synchrotron FT-IR Microspectroscopy Reveals a Link between Neutral Lipid and Storage Carbohydrate Fluxes in S. cerevisiae

PubMed Central

Jamme, Frédéric; Vindigni, Jean-David; Méchin, Valérie; Cherifi, Tamazight; Chardot, Thierry; Froissard, Marine

2013-01-01

In most organisms, storage lipids are packaged into specialized structures called lipid droplets. These contain a core of neutral lipids surrounded by a monolayer of phospholipids, and various proteins which vary depending on the species. Hydrophobic structural proteins stabilize the interface between the lipid core and aqueous cellular environment (perilipin family of proteins, apolipoproteins, oleosins). We developed a genetic approach using heterologous expression in Saccharomyces cerevisiae of the Arabidopsis thaliana lipid droplet oleosin and caleosin proteins AtOle1 and AtClo1. These transformed yeasts overaccumulate lipid droplets, leading to a specific increase in storage lipids. The phenotype of these cells was explored using synchrotron FT-IR microspectroscopy to investigate the dynamics of lipid storage and cellular carbon fluxes reflected as changes in spectral fingerprints. Multivariate statistical analysis of the data showed a clear effect on storage carbohydrates and more specifically, a decrease in glycogen in our modified strains. These observations were confirmed by biochemical quantification of the storage carbohydrates glycogen and trehalose. Our results demonstrate that neutral lipid and storage carbohydrate fluxes are tightly connected and co-regulated. PMID:24040242

Lipids from the nacreous and prismatic layers of two Pteriomorpha Mollusc shells

NASA Astrophysics Data System (ADS)

Farre, B.; Dauphin, Y.

2009-04-01

Mollusc shells are the best-known Ca-carbonate biominerals. They are commonly described as a mineralized two layered structure: an outer layer composed of calcite prismatic units, and an internal layer composed of tablets of aragonite: the nacreous layer. An external organic layer (periostracum) is present in most taxa. However, the most common structure in the Mollusc shell is the aragonite crossed lamellar layer, but aragonite prisms, calcite foliated layers and homogeneous layers have been also described by Boggild (1930) in all the Mollusc orders. Since, more detailed descriptions of Bivalve shells have been done (Taylor et al., 1969, 1973). Despite the nacroprismatic arrangement is rare, calcite prismatic and aragonite nacreous layers are the best studied because of their simple 3D structure and large units. Among these Molluscs, some Bivalve species composed of these two layers are of commercial interest, such as the pearl oyster, Pinctada margaritifera, cultivated in French Polynesia to produce black pearls. It is well established that Mollusc shells are composite structures of organic and inorganic components (Hatchett, 1799; Grégoire et al., 1955; Beedham, 1958; Simkiss, 1965; Mutvei, 1969; Cuif et al., 1980; Berman et al., 1993; Kobayashi and Samata, 2006). Numerous studies are concerned with the organic matrix of the shell. Organic components are commonly obtained after a strong or mild decalcification process. They are said to consist of both a soluble and insoluble fraction. The main part of studies is dedicated to the soluble components, and among them, proteins (Grégoire et al., 1955; Grégoire, 1961; Krampitz et al., 1976; Samata et al., 1980, 2004; Weiner, 1983; Miyamoto et al., 2006). Despite the pioneering work of Wada (1980) sugars are usually neglected despite their role in biomineralization. The third component of the organic matrix of calcareous biominerals is lipids. To date, there is a paucity of information concerning the presence, abundance and composition of these components in Mollusc shells. Goulletquer and Wolowicz (1989) have estimated that proteins represent 90% of the organic matrix of the shell, carbohydrates vary from 0.15 to 0.29%, while lipids vary from 0.8 to 2.9%. Fatty acids, cholesterol, phytadienes and ketones have been described in modern and fossil shells (Cobabe and Pratt, 1995). Using a procedure to extract intra- and intercrystalline organic matrices, Collins et al. (1995) have detected n-alkanes, n-alcohols, fatty acids and sterols in modern shells. It is suggested that the contents and ratios of these components are dependant on the environment and phylogeny. Lipids of the nacreous layer of Pinctada are diverse, with cholesterol, fatty acids, triglycerides and other unknown components (Rousseau et al., 2006). It has been established that the main part of the soluble organic matrices of the nacreous layer is composed of acidic proteins (Samata, 1988, 1990), whereas the prismatic layer of Pinna is mainly composed of acidic and sulphated polysaccharides (Dauphin, 2002; Dauphin et al., 2003). The amino acid compositions of the two layers are also different (Samata, 1990). Because the organic matrices extracted from the aragonite nacre and calcite prisms are the best known materials, the lipids extracted from the calcite prisms of Pinna nobilis and Pinctada margaritifera and the aragonite nacre of P. margaritifera have been chosen as test material for characterisation of the lipid fraction of molusk shells. The nacreous layer of Pinctada is thick,whereas its prismatic layer is thin, and the prisms display complex structures. On the opposite, the calcitic prismatic layer of Pinna is thick, with no intraprismatic membranes, and its nacreous layer is thin and present only in the oldest part of the shell. Moreover, these layers have a simple geometry so that some organic components (membranes, wall…) said to be insoluble, are clearly visible. Lipids were extracted from the calcite prismatic and aragonite nacreous layer of two mollusc shells thanks organic solvents. Two methods were used for the characterisation of the lipid obtaiened Fourier Tranform Infrared Spectrometry and thin layed chromatography. Fourier Transform Infrared Spectrometry shows that lipids are present in both samples, but they are not similar. Thin layer chromatography confirms that lipids are different in the two studied layers, so that it may be suggested they are species-dependant, but also structure-dependant. Although not yet deciphered, their role in biomineralization and fossilisation processes is probably important.

Lipids and RNA virus replication.

PubMed

Konan, Kouacou V; Sanchez-Felipe, Lorena

2014-12-01

Most viruses rely heavily on their host machinery to successfully replicate their genome and produce new virus particles. Recently, the interaction of positive-strand RNA viruses with the lipid biosynthetic and transport machinery has been the subject of intense investigation. In this review, we will discuss the contribution of various host lipids and related proteins in RNA virus replication and maturation. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparative lipid production by oleaginous yeasts in hydrolyzates of lignocellulosic biomass and process strategy for high titers.

PubMed

Slininger, Patricia J; Dien, Bruce S; Kurtzman, Cletus P; Moser, Bryan R; Bakota, Erica L; Thompson, Stephanie R; O'Bryan, Patricia J; Cotta, Michael A; Balan, Venkatesh; Jin, Mingjie; Sousa, Leonardo da Costa; Dale, Bruce E

2016-08-01

Oleaginous yeasts can convert sugars to lipids with fatty acid profiles similar to those of vegetable oils, making them attractive for production of biodiesel. Lignocellulosic biomass is an attractive source of sugars for yeast lipid production because it is abundant, potentially low cost, and renewable. However, lignocellulosic hydrolyzates are laden with byproducts which inhibit microbial growth and metabolism. With the goal of identifying oleaginous yeast strains able to convert plant biomass to lipids, we screened 32 strains from the ARS Culture Collection, Peoria, IL to identify four robust strains able to produce high lipid concentrations from both acid and base-pretreated biomass. The screening was arranged in two tiers using undetoxified enzyme hydrolyzates of ammonia fiber expansion (AFEX)-pretreated cornstover as the primary screening medium and acid-pretreated switch grass as the secondary screening medium applied to strains passing the primary screen. Hydrolyzates were prepared at ∼18-20% solids loading to provide ∼110 g/L sugars at ∼56:39:5 mass ratio glucose:xylose:arabinose. A two stage process boosting the molar C:N ratio from 60 to well above 400 in undetoxified switchgrass hydrolyzate was optimized with respect to nitrogen source, C:N, and carbon loading. Using this process three strains were able to consume acetic acid and nearly all available sugars to accumulate 50-65% of cell biomass as lipid (w/w), to produce 25-30 g/L lipid at 0.12-0.22 g/L/h and 0.13-0.15 g/g or 39-45% of the theoretical yield at pH 6 and 7, a performance unprecedented in lignocellulosic hydrolyzates. Three of the top strains have not previously been reported for the bioconversion of lignocellulose to lipids. The successful identification and development of top-performing lipid-producing yeast in lignocellulose hydrolyzates is expected to advance the economic feasibility of high quality biodiesel and jet fuels from renewable biomass, expanding the market potential for lignocellulose-derived fuels beyond ethanol for automobiles to the entire U.S. transportation market. Biotechnol. Bioeng. 2016;113: 1676-1690. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Dynamic association with donor cell filopodia and lipid-modification are essential features of Wnt8a during patterning of the zebrafish neuroectoderm.

PubMed

Luz, Marta; Spannl-Müller, Stephanie; Özhan, Günes; Kagermeier-Schenk, Birgit; Rhinn, Muriel; Weidinger, Gilbert; Brand, Michael

2014-01-01

Wnt proteins are conserved signaling molecules that regulate pattern formation during animal development. Many Wnt proteins are post-translationally modified by addition of lipid adducts. Wnt8a provides a crucial signal for patterning the anteroposterior axis of the developing neural plate in vertebrates. However, it is not clear how this protein propagates from its source, the blastoderm margin, to the target cells in the prospective neural plate, and how lipid-modifications might influence Wnt8a propagation and activity. We have dynamically imaged biologically active, fluorescently tagged Wnt8a in living zebrafish embryos. We find that Wnt8a localizes to membrane-associated, punctate structures in live tissue. In Wnt8a expressing cells, these puncta are found on filopodial cellular processes, from where the protein can be released. In addition, Wnt8a is found colocalized with Frizzled receptor-containing clusters on signal receiving cells. Combining in vitro and in vivo assays, we compare the roles of conserved Wnt8a residues in cell and non-cell-autonomous signaling activity and secretion. Non-signaling Wnt8 variants show these residues can regulate Wnt8a distribution in producing cell membranes and filopodia as well as in the receiving tissue. Together, our results show that Wnt8a forms dynamic clusters found on filopodial donor cell and on signal receiving cell membranes. Moreover, they demonstrate a differential requirement of conserved residues in Wnt8a protein for distribution in producing cells and receiving tissue and signaling activity during neuroectoderm patterning.

Dynamic Association with Donor Cell Filopodia and Lipid-Modification Are Essential Features of Wnt8a during Patterning of the Zebrafish Neuroectoderm

PubMed Central

Luz, Marta; Spannl-Müller, Stephanie; Özhan, Günes; Kagermeier-Schenk, Birgit; Rhinn, Muriel; Weidinger, Gilbert; Brand, Michael

2014-01-01

Background Wnt proteins are conserved signaling molecules that regulate pattern formation during animal development. Many Wnt proteins are post-translationally modified by addition of lipid adducts. Wnt8a provides a crucial signal for patterning the anteroposterior axis of the developing neural plate in vertebrates. However, it is not clear how this protein propagates from its source, the blastoderm margin, to the target cells in the prospective neural plate, and how lipid-modifications might influence Wnt8a propagation and activity. Results We have dynamically imaged biologically active, fluorescently tagged Wnt8a in living zebrafish embryos. We find that Wnt8a localizes to membrane-associated, punctate structures in live tissue. In Wnt8a expressing cells, these puncta are found on filopodial cellular processes, from where the protein can be released. In addition, Wnt8a is found colocalized with Frizzled receptor-containing clusters on signal receiving cells. Combining in vitro and in vivo assays, we compare the roles of conserved Wnt8a residues in cell and non-cell-autonomous signaling activity and secretion. Non-signaling Wnt8 variants show these residues can regulate Wnt8a distribution in producing cell membranes and filopodia as well as in the receiving tissue. Conclusions Together, our results show that Wnt8a forms dynamic clusters found on filopodial donor cell and on signal receiving cell membranes. Moreover, they demonstrate a differential requirement of conserved residues in Wnt8a protein for distribution in producing cells and receiving tissue and signaling activity during neuroectoderm patterning. PMID:24427298

Docosahexaenoic acid loaded lipid nanoparticles with bactericidal activity against Helicobacter pylori.

PubMed

Seabra, Catarina Leal; Nunes, Cláudia; Gomez-Lazaro, Maria; Correia, Marta; Machado, José Carlos; Gonçalves, Inês C; Reis, Celso A; Reis, Salette; Martins, M Cristina L

2017-03-15

Docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid present in fish oil, has been described as a promising molecule to the treatment of Helicobacter pylori gastric infection. However, due to its highly unsaturated structure, DHA can be easily oxidized loosing part of its bioactivity. This work aims the nanoencapsulation of DHA to improve its bactericidal efficacy against H. pylori. DHA was loaded into nanostructured lipid carriers (NLC) produced by hot homogenization and ultrasonication using a blend of lipids (Precirol ATO5 ® , Miglyol-812 ® ) and a surfactant (Tween 60 ® ). Homogeneous NLC with 302±14nm diameter, -28±3mV surface charge (dynamic and electrophoretic light scattering) and containing 66±7% DHA (UV/VIS spectroscopy) were successfully produced. Bacterial growth curves, performed over 24h in the presence of different DHA concentrations (free or loaded into NLC), demonstrated that nanoencapsulation enhanced DHA bactericidal effect, since DHA-loaded NLC were able to inhibit H. pylori growth in a much lower concentrations (25μM) than free DHA (>100μM). Bioimaging studies, using scanning and transmission electron microscopy and also imaging flow cytometry, demonstrated that DHA-loaded NLC interact with H. pylori membrane, increasing their periplasmic space and disrupting membrane and allowing the leakage of cytoplasmic content. Furthermore, the developed nanoparticles are not cytotoxic to human gastric adenocarcinoma cells at bactericidal concentrations. DHA-loaded NLC should, therefore, be envisaged as an alternative to the current treatments for H. pylori infection. Copyright © 2017 Elsevier B.V. All rights reserved.

[Characterization of an extracellular glycolipid from Lentinus edodes (Berk.) Sing [Lentinula edodes (Berk.) Pegler

PubMed

Tsivileva, O M; Nikitina, V E; Makarov, O E

2008-01-01

Submerged mycelium of a xylotrophic basidiomycete Lentinus edodes produces an extracellular glycolipid, S3, associated with a lectin. Galactose glycan residue, as well as the lipid pool composition, which includes nonhydroxylated short-chain fatty acids, is uncommon for basidiomycetes. The glycolipid consists of D-galactopyranose (15% of S3 contains galactose sulfate) acylated by octadecanoic and nonadecanoic fatty acid residues (28 and 72%, respectively). The glycolipid structure and composition are confirmed by physicochemical analysis. The glycolipid is assumed to be a regulator of lectin activity.

Isolation, identification and characterization of Cystobasidium oligophagum JRC1: A cellulase and lipase producing oleaginous yeast.

PubMed

Vyas, Sachin; Chhabra, Meenu

2017-01-01

Oleaginous yeast closely related to Cystobasidium oligophagum was isolated from soil rich in cellulosic waste. The yeast was isolated based on its ability to accumulate intracellular lipid, grow on carboxymethylcellulose (CMC) and produce lipase. It could accumulate up to 39.44% lipid in a glucose medium (12.45±0.97g/l biomass production). It was able to grow and accumulate lipids (36.46%) in the medium containing CMC as the sole carbon source. The specific enzyme activities obtained for endoglucanase, exoglucanase, and β-glucosidase were 2.27, 1.26, and 0.98IU/mg respectively. The specific enzyme activities obtained for intracellular and extracellular lipase were 2.16 and 2.88IU/mg respectively. It could grow and accumulate lipids in substrates including glycerol (42.04%), starch (41.54%), xylose (36.24%), maltose (26.31%), fructose (24.29%), lactose (21.91%) and sucrose (21.72%). The lipid profile of the organism was suitable for obtaining biodiesel with desirable fuel properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanical collapse of confined fluid membrane vesicles.

PubMed

Rim, Jee E; Purohit, Prashant K; Klug, William S

2014-11-01

Compact cylindrical and spherical invaginations are common structural motifs found in cellular and developmental biology. To understand the basic physical mechanisms that produce and maintain such structures, we present here a simple model of vesicles in confinement, in which mechanical equilibrium configurations are computed by energy minimization, balancing the effects of curvature elasticity, contact of the membrane with itself and the confining geometry, and adhesion. For cylindrical confinement, the shape equations are solved both analytically and numerically by finite element analysis. For spherical confinement, axisymmetric configurations are obtained numerically. We find that the geometry of invaginations is controlled by a dimensionless ratio of the adhesion strength to the bending energy of an equal area spherical vesicle. Larger adhesion produces more concentrated curvatures, which are mainly localized to the "neck" region where the invagination breaks away from its confining container. Under spherical confinement, axisymmetric invaginations are approximately spherical. For extreme confinement, multiple invaginations may form, bifurcating along multiple equilibrium branches. The results of the model are useful for understanding the physical mechanisms controlling the structure of lipid membranes of cells and their organelles, and developing tissue membranes.

Structural and functional changes in acute liver injury.

PubMed

Smuckler, E A

1976-06-01

Carbon tetrachloride produces liver cell injury in a variety of animal species. The first structurally recognizable changes occur in the endoplasmic reticulum, with alteration in ribosome-membrane interactions. Later there is an increase in intracellular fat, and the formation of tangled nets of the ergastoplasm. At no time are there changes in mitochondria or single membrane limited bodies in cells with intact plasmalemma, although a relative increase in cell sap may appear. In dead cells (those with plasmalemma discontinuties) crystalline deposits of calcium phosphatase may be noted. Functional changes are related to the endoplasmic reticulum and the plasma membrane. An early decrease in protein synthesis takes place; an accumulation of neutral lipid is related to this change. Later alterations in the ergastoplasmic functions (e.g., mixed function oxidation) occurs. Carbon tetrachloride is not the active agent; rather, a product of its metabolism, probably the CC1, free radical, is. The mechanisms of injury include macromolecular adduction and peroxide propagation. A third possibility includes a cascade effect with the production of secondary and tertiary products, also toxic in nature, with the ability to produce more widespread damage to intracellular structures.

'Click' synthesized sterol-based cationic lipids as gene carriers, and the effect of skeletons and headgroups on gene delivery.

PubMed

Sheng, Ruilong; Luo, Ting; Li, Hui; Sun, Jingjing; Wang, Zhao; Cao, Amin

2013-11-01

In this work, we have successfully prepared a series of new sterol-based cationic lipids (1-4) via an efficient 'Click' chemistry approach. The pDNA binding affinity of these lipids was examined by EB displacement and agarose-gel retardant assay. The average particle sizes and surface charges of the sterol-based cationic lipids/pDNA lipoplexes were analyzed by dynamic laser light scattering instrument (DLS), and the morphologies of the lipoplexes were observed by atomic force microscopy (AFM). The cytotoxicity of the lipids were examined by MTT and LDH assay, and the gene transfection efficiencies of these lipid carriers were investigated by luciferase gene transfection assay in various cell lines. In addition, the intracellular uptake and trafficking/localization behavior of the Cy3-DNA loaded lipoplexes were preliminarily studied by fluorescence microscopy. The results demonstrated that the pDNA loading capacity, lipoplex particle size, zeta potential and morphology of the sterol lipids/pDNA lipoplexes depended largely on the molecular structure factors including sterol-skeletons and headgroups. Furthermore, the sterol-based lipids showed quite different cytotoxicity and gene transfection efficacy in A549 and HeLa cells. Interestingly, it was found that the cholesterol-bearing lipids 1 and 2 showed 7-10(4) times higher transfection capability than their lithocholate-bearing counterparts 3 and 4 in A549 and HeLa cell lines, suggested that the gene transfection capacity strongly relied on the structure of sterol skeletons. Moreover, the study on the structure-activity relationships of these sterol-based cationic lipid gene carriers provided a possible approach for developing low cytotoxic and high efficient lipid gene carriers by selecting suitable sterol hydrophobes and cationic headgroups. Copyright © 2013 Elsevier Ltd. All rights reserved.

Concurrent production of carotenoids and lipid by a filamentous microalga Trentepohlia arborum.

PubMed

Chen, Lin; Zhang, Lanlan; Liu, Tianzhong

2016-08-01

During the study of Trentepohlia arborum it became clear that its cells are rich in lipids and carotenoids. Thus, lipid content, composition and fatty acids profiles in individual lipid classes, as well as pigment profiles, responding to different culture conditions, were further investigated. The results showed that the predominant carotenoids and lipid fraction in total lipid in this study was β-carotene and TAG, respectively. The lipid content increased significantly under high light while nitrogen-replete conditions induced the highest carotenoids content. However, only with a double stress of high light and nitrogen-deficiency it was possible to maximize the productivities of both carotenoids and lipids. Carotenoids (mainly β-carotene) accounted for ca. 5% of the microalgal lipid under the double stress. Data herein show the potential of T. arborum for the production of both lipids and carotenoids, and hence provide an appropriate way to produce different products from T. arborum. Copyright © 2016 Elsevier Ltd. All rights reserved.

Molecular architecture of plant thylakoids under physiological and light stress conditions: a study of lipid-light-harvesting complex II model membranes.

PubMed

Janik, Ewa; Bednarska, Joanna; Zubik, Monika; Puzio, Michal; Luchowski, Rafal; Grudzinski, Wojciech; Mazur, Radoslaw; Garstka, Maciej; Maksymiec, Waldemar; Kulik, Andrzej; Dietler, Giovanni; Gruszecki, Wieslaw I

2013-06-01

In this study, we analyzed multibilayer lipid-protein membranes composed of the photosynthetic light-harvesting complex II (LHCII; isolated from spinach [Spinacia oleracea]) and the plant lipids monogalcatosyldiacylglycerol and digalactosyldiacylglycerol. Two types of pigment-protein complexes were analyzed: those isolated from dark-adapted leaves (LHCII) and those from leaves preilluminated with high-intensity light (LHCII-HL). The LHCII-HL complexes were found to be partially phosphorylated and contained zeaxanthin. The results of the x-ray diffraction, infrared imaging microscopy, confocal laser scanning microscopy, and transmission electron microscopy revealed that lipid-LHCII membranes assemble into planar multibilayers, in contrast with the lipid-LHCII-HL membranes, which form less ordered structures. In both systems, the protein formed supramolecular structures. In the case of LHCII-HL, these structures spanned the multibilayer membranes and were perpendicular to the membrane plane, whereas in LHCII, the structures were lamellar and within the plane of the membranes. Lamellar aggregates of LHCII-HL have been shown, by fluorescence lifetime imaging microscopy, to be particularly active in excitation energy quenching. Both types of structures were stabilized by intermolecular hydrogen bonds. We conclude that the formation of trans-layer, rivet-like structures of LHCII is an important determinant underlying the spontaneous formation and stabilization of the thylakoid grana structures, since the lamellar aggregates are well suited to dissipate excess energy upon overexcitation.

In situ AFM imaging of apolipoprotein A-I directly derived from plasma HDL.

PubMed

Gan, Chaoye; Wang, Zhexuan; Chen, Yong

2017-04-01

The major apolipoproteins of plasma lipoproteins play vital roles in the structural integrity and physiological functions of lipoproteins. More than ten structural models of apolipoprotein A-I (apoA-I), the major apolipoprotein of high-density lipoprotein (HDL), have been developed successively. In these models, apoA-I was supposed to organize in a ring-shaped form. To date, however, there is no direct evidence under physiological condition. Here, atomic force microscopy (AFM) was used to in situ visualize the organization of apoA-I, which was exposed via depletion of the lipid component of plasma HDL pre-immobilized on functionalized mica sheets. For the first time, the ring-shaped coarse structure and three detailed structures (crescent-shaped, gapped "O"-shaped, and parentheses-shaped structures, respectively) of apoA-I in plasma HDL, which have the ability of binding scavenger receptors, were directly observed and quantitatively measured by AFM. The three detailed structures probably represent the different extents to which the lipid component of HDL was depleted. Data on lipid depletion of HDL may provide clues to understand lipid insertion of HDL. These data provide important information for the understanding of the structure/maturation of plasma HDL. Moreover, they suggest a powerful method for directly visualizing the major apolipoproteins of plasma lipoproteins or the protein component of lipoprotein-like lipid-protein complexes. Copyright © 2017 Elsevier B.V. All rights reserved.

Joint small-angle X-ray and neutron scattering data analysis of asymmetric lipid vesicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eicher, Barbara; Heberle, Frederick A.; Marquardt, Drew T.

2017-02-28

Low- and high-resolution models describing the internal transbilayer structure of asymmetric lipid vesicles have been developed. These models can be used for the joint analysis of small-angle neutron and X-ray scattering data. The models describe the underlying scattering length density/electron density profiles either in terms of slabs or through the so-called scattering density profile, previously applied to symmetric lipid vesicles. Both models yield structural details of asymmetric membranes, such as the individual area per lipid, and the hydrocarbon thickness of the inner and outer bilayer leaflets. The scattering density profile model, however, comes at a cost of increased computational effortmore » but results in greater structural resolution, showing a slightly lower packing of lipids in the outer bilayer leaflet of ~120 nm diameter palmitoyloleoyl phosphatidylcholine (POPC) vesicles, compared to the inner leaflet. Here, analysis of asymmetric dipalmitoyl phosphatidylcholine/POPC vesicles did not reveal evidence of transbilayer coupling between the inner and outer leaflets at 323 K, i.e.above the melting transition temperature of the two lipids.« less

Small Angle X-Ray Scattering from Lipid-Bound Myelin Basic Protein in Solution

PubMed Central

Haas, H.; Oliveira, C. L. P.; Torriani, I. L.; Polverini, E.; Fasano, A.; Carlone, G.; Cavatorta, P.; Riccio, P.

2004-01-01

The structure of myelin basic protein (MBP), purified from the myelin sheath in both lipid-free (LF-MBP) and lipid-bound (LB-MBP) forms, was investigated in solution by small angle x-ray scattering. The water-soluble LF-MBP, extracted at pH < 3.0 from defatted brain, is the classical preparation of MBP, commonly regarded as an intrinsically unfolded protein. LB-MBP is a lipoprotein-detergent complex extracted from myelin with its native lipidic environment at pH > 7.0. Under all conditions, the scattering from the two protein forms was different, indicating different molecular shapes. For the LB-MBP, well-defined scattering curves were obtained, suggesting that the protein had a unique, compact (but not globular) structure. Furthermore, these data were compatible with earlier results from molecular modeling calculations on the MBP structure which have been refined by us. In contrast, the LF-MBP data were in accordance with the expected open-coil conformation. The results represent the first direct structural information from x-ray scattering measurements on MBP in its native lipidic environment in solution. PMID:14695288

Conformation and molecular topography of the N-terminal segment of surfactant protein B in structure-promoting environments.

PubMed Central

Gordon, L. M.; Horvath, S.; Longo, M. L.; Zasadzinski, J. A.; Taeusch, H. W.; Faull, K.; Leung, C.; Waring, A. J.

1996-01-01

Although the effects of surfactant protein B (SP-B) on lipid surface activity in vitro and in vivo are well known, the relationship between molecular structure and function is still not fully understood. To further characterize protein structure-activity correlations, we have used physical techniques to study conformation, orientation, and molecular topography of N-terminal SP-B peptides in lipids and structure-promoting environments. Fourier transform infrared (FTIR) and CD measurements of SP-B1-25 (residues 1-25) in methanol, SDS micelles, egg yolk lecithin (EYL) liposomes, and surfactant lipids indicate the peptide has a dominant helical content, with minor turn and disordered components. Polarized FTIR studies of SP-B1-25 indicate the long molecular axis lies at an oblique angle to the surface of lipid films. Truncated peptides were similarly examined to assign more accurately the discrete conformations within the SP-B1-25 sequence. Residues Cys-8-Gly-25 are largely alpha-helix in methanol, whereas the N-terminal segment Phe-1-Cys-8 had turn and helical propensities. Addition of SP-B1-25 spin-labeled at the N-terminal Phe (i.e., SP-B1-25) to SDS, EYL, or surfactant lipids yielded electron spin resonance spectra that reflect peptide bound to lipids, but retaining considerable mobility. The absence of characteristic radical broadening indicates that SP-B1-25 is minimally aggregated when it interacts with these lipids. Further, the high polarity of SP-B1-25 argues that the reporter on Phe-1 resides in the headgroup of the lipid dispersions. The blue-shift in the endogenous fluorescence of Trp-9 near the N-terminus of SP-B1-25 suggests that this residue also lies near the lipid headgroup. A summary model based on the above physical experiments is presented for SP-B1-25 interacting with lipids. PMID:8844855

Investigation of Lipid Metabolism by a New Structured Lipid with Medium- and Long-Chain Triacylglycerols from Cinnamomum camphora Seed Oil in Healthy C57BL/6J Mice.

PubMed

Hu, Jiang-Ning; Shen, Jin-Rong; Xiong, Chao-Yue; Zhu, Xue-Mei; Deng, Ze-Yuan

2018-02-28

In the present study, a new structured lipid with medium- and long-chain triacylglycerols (MLCTs) was synthesized from camellia oil (CO) and Cinnamomum camphora seed oil (CCSO) by enzymatic interesterification. Meanwhile, the antiobesity effects of structured lipid were investigated through observing the changes of enzymes related to lipid mobilization in healthy C57BL/6J mice. Results showed that after synthesis, the major triacylgeride (TAG) species of intesterificated product changed to LaCC/CLaC (12.6 ± 0.46%), LaCO/LCL (21.7 ± 0.76%), CCO/LaCL (14.2 ± 0.55%), COO/OCO (10.8 ± 0.43%), and OOO (18.6 ± 0.64%). Through second-stage molecular distillation, the purity of interesterified product (MLCT) achieved 95.6%. Later, male C57BL/6J mice were applied to study whether the new structured lipid with MLCT has the efficacy of preventing the formation of obesity or not. After feeding with different diets for 6 weeks, MLCTs could reduce body weight and fat deposition in adipose tissue, lower plasma triacylglycerols (TG) (0.89 ± 0.16 mmol/L), plasma total cholesterol (TC) (4.03 ± 0.08 mmol/L), and hepatic lipids (382 ± 34.2 mg/mice) by 28.8%, 16.0%, and 30.5%, respectively, when compared to the control 2 group. This was also accompanied by increasing fecal lipids (113%) and the level of enzymes including cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), hormone-sensitive lipase (HSL), and adipose triglyceride lipase (ATGL) related to lipid mobilization in MLCT group. From the results, it can be concluded that MLCT reduced body fat deposition probably by modulating enzymes related to lipid mobilization in C57BL/6J mice.

Molecular driving forces defining lipid positions around aquaporin-0

PubMed Central

Aponte-Santamaría, Camilo; Briones, Rodolfo; Schenk, Andreas D.; Walz, Thomas; de Groot, Bert L.

2012-01-01

Lipid–protein interactions play pivotal roles in biological membranes. Electron crystallographic studies of the lens-specific water channel aquaporin-0 (AQP0) revealed atomistic views of such interactions, by providing high-resolution structures of annular lipids surrounding AQP0. It remained unclear, however, whether these lipid structures are representative of the positions of unconstrained lipids surrounding an individual protein, and what molecular determinants define the lipid positions around AQP0. We addressed these questions by using molecular dynamics simulations and crystallographic refinement, and calculated time-averaged densities of dimyristoyl-phosphatidylcholine lipids around AQP0. Our simulations demonstrate that, although the experimentally determined crystallographic lipid positions are constrained by the crystal packing, they appropriately describe the behavior of unconstrained lipids around an individual AQP0 tetramer, and thus likely represent physiologically relevant lipid positions.While the acyl chains were well localized, the lipid head groups were not. Furthermore, in silico mutations showed that electrostatic interactions do not play a major role attracting these phospholipids towards AQP0. Instead, the mobility of the protein crucially modulates the lipid localization and explains the difference in lipid density between extracellular and cytoplasmic leaflets. Moreover, our simulations support a general mechanism in which membrane proteins laterally diffuse accompanied by several layers of localized lipids, with the positions of the annular lipids being influenced the most by the protein surface. We conclude that the acyl chains rather than the head groups define the positions of dimyristoyl-phosphatidylcholine lipids around AQP0. Lipid localization is largely determined by the mobility of the protein surface, whereas hydrogen bonds play an important but secondary role. PMID:22679286

High value added lipids produced by microorganisms: a potential use of sugarcane vinasse.

PubMed

Fernandes, Bruna Soares; Vieira, João Paulo Fernandes; Contesini, Fabiano Jares; Mantelatto, Paulo Eduardo; Zaiat, Marcelo; Pradella, José Geraldo da Cruz

2017-12-01

This review aims to present an innovative concept of high value added lipids produced by heterotrophic microorganisms, bacteria and fungi, using carbon sources, such as sugars, acids and alcohols that could come from sugarcane vinasse, which is the main byproduct from ethanol production that is released in the distillation step. Vinasse is a rich carbon source and low-cost feedstock produced in large amounts from ethanol production. In 2019, the Brazilian Ministry of Agriculture, Livestock and Food Supply estimates that growth of ethanol domestic consumption will be 58.8 billion liters, more than double the amount in 2008. This represents the annual production of more than 588 billion liters of vinasse, which is currently used as a fertilizer in the sugarcane crop, due to its high concentration of minerals, mainly potassium. However, studies indicate some disadvantages such as the generation of Greenhouse Gas emission during vinasse distribution in the crop, as well as the possibility of contaminating the groundwater and soil. Therefore, the development of programs for sustainable use of vinasse is a priority. One profitable alternative is the fermentation of vinasse, followed by an anaerobic digester, in order to obtain biomaterials such as lipids, other byproducts, and methane. Promising high value added lipids, for instance carotenoids and polyunsaturated fatty acids (PUFAS), with a predicted market of millions of US$, could be produced using vinasse as carbon source, to guide an innovative concept for sustainable production. Example of lipids obtained from the fermentation of compounds present in vinasse are vitamin D, which comes from yeast sucrose fermentation and Omega 3, which can be obtained by bacteria and fungi fermentation. Additionally, several other compounds present in vinasse can be used for this purpose, including sucrose, ethanol, lactate, pyruvate, acetate and other carbon sources. Finally, this paper illustrates the potential market and microbial processes, using microorganisms, for lipid production.

Melittin-induced cholesterol reorganization in lipid bilayer membranes

DOE PAGES

Qian, Shuo; Heller, William T.

2015-06-12

The peptide melittin, a 26 amino acid, cationic peptide from honey bee ( Apis mellifera) venom, disrupts lipid bilayer membranes in a concentration-dependent manner. Rather than interacting with a specific receptor, the peptide interacts directly with the lipid matrix of the membrane in a manner dependent on the lipid composition. Here, a small-angle neutron scattering study of the interaction of melittin with lipid bilayers made of mixtures of dimyristoylphosphatidylcholine (DMPC) and cholesterol (Chol) is presented. Through the use of deuterium-labeled DMPC, changes in the distribution of the lipid and cholesterol in unilamellar vesicles were observed for peptide concentrations below thosemore » that cause pores to form. In addition to disrupting the in-plane organization of Chol, melittin produces vesicles having inner and outer leaflet compositions that depend on the lipid–Chol molar ratio and on the peptide concentration. The changes seen at high cholesterol and low peptide concentration are similar to those produced by alamethicin (Qian, S. et al., J. Phys. Chem. B 2014, 118, 11200–11208), which points to an underlying physical mechanism driving the redistribution of Chol, but melittin displays an additional effect not seen with alamethicin. Furthermore, a model for how the peptide drives the redistribution of Chol is proposed. The results suggest that redistribution of the lipids in a target cell membrane by membrane active peptides takes places as a prelude to the lysis of the cell.« less

Melittin-induced cholesterol reorganization in lipid bilayer membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Shuo; Heller, William T.

The peptide melittin, a 26 amino acid, cationic peptide from honey bee ( Apis mellifera) venom, disrupts lipid bilayer membranes in a concentration-dependent manner. Rather than interacting with a specific receptor, the peptide interacts directly with the lipid matrix of the membrane in a manner dependent on the lipid composition. Here, a small-angle neutron scattering study of the interaction of melittin with lipid bilayers made of mixtures of dimyristoylphosphatidylcholine (DMPC) and cholesterol (Chol) is presented. Through the use of deuterium-labeled DMPC, changes in the distribution of the lipid and cholesterol in unilamellar vesicles were observed for peptide concentrations below thosemore » that cause pores to form. In addition to disrupting the in-plane organization of Chol, melittin produces vesicles having inner and outer leaflet compositions that depend on the lipid–Chol molar ratio and on the peptide concentration. The changes seen at high cholesterol and low peptide concentration are similar to those produced by alamethicin (Qian, S. et al., J. Phys. Chem. B 2014, 118, 11200–11208), which points to an underlying physical mechanism driving the redistribution of Chol, but melittin displays an additional effect not seen with alamethicin. Furthermore, a model for how the peptide drives the redistribution of Chol is proposed. The results suggest that redistribution of the lipids in a target cell membrane by membrane active peptides takes places as a prelude to the lysis of the cell.« less

Lipids of Pseudomonas aeruginosa Cells Grown on Hydrocarbons and on Trypticase Soy Broth1

PubMed Central

Edmonds, Paul; Cooney, J. J.

1969-01-01

Lipids were extracted from cells of Pseudomonas aeruginosa grown on a pure hydrocarbon (tridecane), mixed hydrocarbons (JP-4 jet fuel), and on Trypticase Soy Broth. Total lipids produced from each substrate represented from 7.1 to 8.2% of cellular dry weight, of which 5.0 to 6.4% were obtained before cellular hydrolysis (free lipids) and 1.7 to 2.0% were extracted after cellular hydrolysis (bound lipids). Free lipids from cells grown on each medium were separated into four fractions by thin-layer chromatography. All fractions were present in cells from each type of medium, and the “neutral fraction” constituted the largest fraction. The fatty acid composition of free lipids was determined by gas-liquid chromatography. Cells grown on each medium contained saturated and unsaturated C14 to C20 fatty acids. Trace amounts of C13 fatty acids were found in tridecane-grown cells. Saturated C16 and C18 were the major acids present in all cells. Quantitative differences were found in fatty acids produced on the three media, but specific correlations between substrate carbon sources and fatty acid content of cells were not evident. Tridecane-grown cells contained only traces of C13 acid and small amounts of C15 and C17 acids, suggesting that the organism's fatty acids were derived from de novo synthesis rather than by direct incorporation of the hydrocarbon. PMID:4976464

Amyloid fibril formation of peptides derived from the C-terminus of CETP modulated by lipids

DOE Office of Scientific and Technical Information (OSTI.GOV)

García-González, Victor; Mas-Oliva, Jaime, E-mail: jmas@ifc.unam.mx; División de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510 México, DF

2013-04-26

Highlights: •The secondary structure of a C-terminal peptide derived from CETP was studied. •Lipids modulate secondary structure changes of a C-terminal peptide derived from CETP. •Lysophosphatidic acid maintains a functional α-helix and prevents fibril formation. •Transfer of lipids by CETP is related to the presence of an α-helix at its C-end. -- Abstract: Cholesteryl-ester transfer protein (CETP) is a plasmatic protein involved in neutral lipid transfer between lipoproteins. Focusing on the last 12 C-terminus residues we have previously shown that mutation D{sub 470}N promotes a conformational change towards a β-secondary structure. In turn, this modification leads to the formation ofmore » oligomers and fibrillar structures, which cause cytotoxic effects similar to the ones provoked by amyloid peptides. In this study, we evaluated the role of specific lipid arrangements on the structure of peptide helix-Z (D{sub 470}N) through the use of thioflavin T fluorescence, peptide bond absorbance, circular dichroism and electron microscopy. The results indicate that the use of micelles formed with lysophosphatidylcholine and lysophosphatidic acid (LPA) under neutral pH induce a conformational transition of peptide helix-Z containing a β-sheet conformation to a native α-helix structure, therefore avoiding the formation of amyloid fibrils. In contrast, incubation with phosphatidic acid does not change the profile for the β-sheet conformation. When the electrostatic charge at the surface of micelles or vesicles is regulated through the use of lipids such as phospholipid and LPA, minimal changes and the presence of β-structures were recorded. Mixtures with a positive net charge diminished the percentage of β-structure and the amount of amyloid fibrils. Our results suggest that the degree of solvation determined by the presence of a free hydroxyl group on lipids such as LPA is a key condition that can modulate the secondary structure and the consequent formation of amyloid fibrils in the highly flexible C-terminus domain of CETP.« less

Reconstitution of the Hepatic Asialoglycoprotein Receptor with Phospholipid Vesicles

NASA Astrophysics Data System (ADS)

Klausner, Richard D.; Bridges, Kenneth; Tsunoo, Hajime; Blumenthal, Robert; Weinstein, John N.; Ashwell, Gilbert

1980-09-01

A solubilized detergent-free preparation of the hepatic binding protein specific for asialoglycoproteins associates spontaneously with small unilamellar lipid vesicles. This process is independent of the phase transition of the lipid and effectively restores the specific binding activity of the receptor protein. The insensitivity of the resulting lipid-protein complex to ionic strength provides evidence for a hydrophobic interaction. There is a perturbation of the lipid phase transition concomitant with addition of the protein. Circular dichroism studies indicate that the protein undergoes a conformational change on association with lipid. Binding of specific ligand produces further physical changes in the receptor as indicated by alterations in the tryptophan fluorescence quenching pattern.

Peptide-Lipid Interactions: Experiments and Applications

PubMed Central

Galdiero, Stefania; Falanga, Annarita; Cantisani, Marco; Vitiello, Mariateresa; Morelli, Giancarlo; Galdiero, Massimiliano

2013-01-01

The interactions between peptides and lipids are of fundamental importance in the functioning of numerous membrane-mediated cellular processes including antimicrobial peptide action, hormone-receptor interactions, drug bioavailability across the blood-brain barrier and viral fusion processes. Moreover, a major goal of modern biotechnology is obtaining new potent pharmaceutical agents whose biological action is dependent on the binding of peptides to lipid-bilayers. Several issues need to be addressed such as secondary structure, orientation, oligomerization and localization inside the membrane. At the same time, the structural effects which the peptides cause on the lipid bilayer are important for the interactions and need to be elucidated. The structural characterization of membrane active peptides in membranes is a harsh experimental challenge. It is in fact accepted that no single experimental technique can give a complete structural picture of the interaction, but rather a combination of different techniques is necessary. PMID:24036440

A Neutron View of Proteins in Lipid Bilayers

NASA Astrophysics Data System (ADS)

White, Stephen

2012-02-01

Despite the growing number of atomic-resolution membrane protein structures, direct structural information about proteins in their native membrane environment is scarce. This problem is particularly relevant in the case of the highly-charged S1-S4 voltage- sensing domains responsible for nerve impulses, where interactions with the lipid bilayer are critical for the function of voltage-activated potassium channels. We have used neutron diffraction, solid-state nuclear magnetic resonance spectroscopy, and molecular dynamics simulations to investigate the structure and hydration of bilayer membranes containing S1-S4 voltage-sensing domains. Our results show that voltage sensors adopt transmembrane orientations, cause a modest reshaping of the surrounding lipid bilayer, and that water molecules intimately interact with the protein within the membrane. These structural findings reveal that voltage sensors have evolved to interact with the lipid membrane while keeping the energetic and structural perturbations to a minimum, and that water penetrates into the membrane to hydrate charged residues and shape the transmembrane electric field.

How Membrane-Active Peptides Get into Lipid Membranes.

PubMed

Sani, Marc-Antoine; Separovic, Frances

2016-06-21

The structure-function relationship for a family of antimicrobial peptides (AMPs) from the skin of Australian tree frogs is discussed and compared with that of peptide toxins from bee and Australian scorpion venoms. Although these membrane-active peptides induce a similar cellular fate by disrupting the lipid bilayer integrity, their lytic activity is achieved via different modes of action, which are investigated in relation to amino acid sequence, secondary structure, and membrane lipid composition. In order to better understand what structural features govern the interaction between peptides and lipid membranes, cell-penetrating peptides (CPPs), which translocate through the membrane without compromising its integrity, are also discussed. AMPs possess membrane lytic activities that are naturally designed to target the cellular membrane of pathogens or competitors. They are extremely diverse in amino acid composition and often show specificity against a particular strain of microbe. Since our antibiotic arsenal is declining precariously in the face of the rise in multiantibiotic resistance, AMPs increasingly are seen as a promising alternative. In an effort to understand their molecular mechanism, biophysical studies of a myriad of AMPs have been reported, yet no unifying mechanism has emerged, rendering difficult the rational design of drug leads. Similarly, a wide variety of cytotoxic peptides are found in venoms, the best known being melittin, yet again, predicting their activity based on a particular amino acid composition or secondary structure remains elusive. A common feature of these membrane-active peptides is their preference for the lipid environment. Indeed, they are mainly unstructured in solution and, in the presence of lipid membranes, quickly adsorb onto the surface, change their secondary structure, eventually insert into the hydrophobic core of the membrane bilayer, and finally disrupt the bilayer integrity. These steps define the molecular mechanism by which these membrane-active peptides lyse membranes. The last class of membrane-active peptides discussed are the CPPs, which translocate across the lipid bilayer without inducing severe disruption and have potential as drug vehicles. CPPs are typically highly charged and can show antimicrobial activity by targeting an intracellular target rather than via a direct membrane lytic mechanism. A critical aspect in the structure-function relationship of membrane-active peptides is their specific activity relative to the lipid membrane composition of the cell target. Cell membranes have a wide diversity of lipids, and those of eukaryotic and prokaryotic species differ greatly in composition and structure. The activity of AMPs from Australian tree frogs, toxins, and CPPs has been investigated within various lipid systems to assess whether a relationship between peptide and membrane composition could be identified. NMR spectroscopy techniques are being used to gain atomistic details of how these membrane-active peptides interact with model membranes and cells, and in particular, competitive assays demonstrate the difference between affinity and activity for a specific lipid environment. Overall, the interactions between these relatively small sized peptides and various lipid bilayers give insight into how these peptides function at the membrane interface.

Comparative study of copper(II)-curcumin complexes as superoxide dismutase mimics and free radical scavengers.

PubMed

Barik, Atanu; Mishra, Beena; Kunwar, Amit; Kadam, Ramakant M; Shen, Liang; Dutta, Sabari; Padhye, Subhash; Satpati, Ashis K; Zhang, Hong-Yu; Indira Priyadarsini, K

2007-04-01

Two stoichiometrically different copper(II) complexes of curcumin (stoichiometry, 1:1 and 1:2 for copper:curcumin), were examined for their superoxide dismutase (SOD) activity, free radical-scavenging ability and antioxidant potential. Both the complexes are soluble in lipids and DMSO. The formation constants of the complexes were determined by voltammetry. EPR spectra of the complexes in DMSO at 77K showed that the 1:2 Cu(II)-curcumin complex is square planar and the 1:1 Cu(II)-curcumin complex is distorted orthorhombic. Cu(II)-curcumin complex (1:1) with larger distortion from square planar structure shows higher SOD activity. These complexes inhibit gamma-radiation induced lipid peroxidation in liposomes and react with DPPH acting as free radical scavengers. One-electron oxidation of the two complexes by radiolytically generated azide radicals in Tx-100 micellar solutions produced phenoxyl radicals, indicating that the phenolic moiety of curcumin in the complexes participates in free radical reactions. Depending on the structure, these two complexes possess different SOD activities, free radical neutralizing abilities and antioxidant potentials. In addition, quantum chemical calculations with density functional theory have been performed to support the experimental observations.

Synthesis and characterization of canola oil-stearic acid-based trans-free structured lipids for possible margarine application.

PubMed

Lumor, Stephen E; Jones, Kerby C; Ashby, Rick; Strahan, Gary D; Kim, Byung Hee; Lee, Guan-Chiun; Shaw, Jei-Fu; Kays, Sandra E; Chang, Shu-Wei; Foglia, Thomas A; Akoh, Casimir C

2007-12-26

Incorporation of stearic acid into canola oil to produce trans-free structured lipid (SL) as a healthy alternative to partially hydrogenated fats for margarine formulation was investigated. Response surface methodology was used to study the effects of lipozyme RM IM from Rhizomucor miehei and Candida rugosa lipase isoform 1 (LIP1) and two acyl donors, stearic acid and ethyl stearate, on the incorporation. Lipozyme RM IM and ethyl stearate gave the best result. Gram quantities of SLs were synthesized using lipozyme RM IM, and the products were compared to SL made by chemical catalysis and fat from commercial margarines. After short-path distillation, the products were characterized by GC and RPHPLC-MS to obtain fatty acid and triacylglycerol profiles, 13C NMR spectrometry for regiospecific analysis, X-ray diffraction for crystal forms, and DSC for melting profile. Stearic acid was incorporated into canola oil, mainly at the sn-1,3 positions, for the lipase reaction, and no new trans fatty acids formed. Most SL products did not have adequate solid fat content or beta' crystal forms for tub margarine, although these may be suitable for light margarine formulation.

Synthesis of structured lipids by transesterification of trilinolein catalyzed by Lipozyme IM60.

PubMed

Sellappan, S; Akoh, C C

2001-04-01

Structured lipids (SL) containing caprylic, stearic, and linoleic acids were synthesized by enzymatic transesterification using Lipozyme IM60. Pure trilinolein and free fatty acids were used as substrates. Incorporation of stearic acid was higher than that of caprylic acid in all parameters. Highest incorporations of both acids were achieved at 32 h, mole ratio of 1:4:4 (trilinolein/caprylic/stearic acids), water content of 1% (wt %), temperature of 55 degrees C, and 10% (wt %) enzyme load. The maximal incorporations of caprylic and stearic acids were 23.73 and 62.46 mol %, respectively. Reaction time, water content, and enzyme load had major influences on the reaction, whereas substrate mole ratio and temperature showed less influence. Lipozyme showed good stability over six reuses. Differential scanning calorimetric analysis of SL gave a melting profile with a very low melting peak of 0-3.3 degrees C and a solid fat content of 25.21% at 0 degrees C. The melting profile and solid fat content of SL were compared with those of fats extracted from commercially available solid and liquid margarine products. The data suggest that enzymatically produced SL could be used in liquid margarine products.

Molecular modeling of biomembranes and their complexes with protein transmembrane α-helices

NASA Astrophysics Data System (ADS)

Kuznetsov, Andrey S.; Smirnov, Kirill V.; Antonov, Mikhail Yu.; Nikolaev, Ivan N.; Efremov, Roman G.

2017-11-01

Helical segments are common structural elements of membrane proteins. Dimerization and oligomerization of transmembrane (TM) α-helices provides the framework for spatial structure formation and protein-protein interactions. The membrane itself also takes part in the protein functioning. There are some examples of the mutual influence of the lipid bilayer properties and embedded membrane proteins. This work aims at the detail investigation of protein-lipid interactions using model systems: TM peptides corresponding to native protein segments. Three peptides were considered corresponding to TM domains of human glycophorin A (GpA), epidermal growth factor receptor (EGFR) and proposed TM-segment of human neuraminidase-1 (Neu1). A computational analysis of structural and dynamical properties was performed using molecular dynamics method. Monomers of peptides were considered incorporated into hydrated lipid bilayers. It was confirmed, that all these TM peptides have stable helical conformation in lipid environment, and the mutual adaptation of peptides and membrane was observed. It was shown that incorporation of the peptide into membrane results in the modulation of local and mean structural properties of the bilayer. Each peptide interacts with lipid acyl chains having special binding sites on the surface of central part of α-helix that exist for at least 200 ns. However, lipid acyl chains substitute each other faster occupying the same site. The formation of a special pattern of protein-lipid interactions may modulate the association of TM domains of membrane proteins, so membrane environment should be considered when proposing new substances targeting cell receptors.

Lipids, curvature, and nano-medicine*

PubMed Central

Mouritsen, Ole G

2011-01-01

The physical properties of the lamellar lipid-bilayer component of biological membranes are controlled by a host of thermodynamic forces leading to overall tensionless bilayers with a conspicuous lateral pressure profile and build-in curvature-stress instabilities that may be released locally or globally in terms of morphological changes. In particular, the average molecular shape and the propensity of the different lipid and protein species for forming non-lamellar and curved structures are a source of structural transitions and control of biological function. The effects of different lipids, sterols, and proteins on membrane structure are discussed and it is shown how one can take advantage of the curvature-stress modulations brought about by specific molecular agents, such as fatty acids, lysolipids, and other amphiphilic solutes, to construct intelligent drug-delivery systems that function by enzymatic triggering via curvature. Practical applications: The simple concept of lipid molecular shape and how it impacts on the structure of lipid aggregates, in particular the curvature and curvature stress in lipid bilayers and liposomes, can be exploited to construct liposome-based drug-delivery systems, e.g., for use as nano-medicine in cancer therapy. Non-lamellar-forming lysolipids and fatty acids, some of which may be designed to be prodrugs, can be created by phospholipase action in diseased tissues thereby providing for targeted drug release and proliferation of molecular entities with conical shape that break down the permeability barrier of the target cells and may hence enhance efficacy. PMID:22164124

Structure and Stability of the Spinach Aquaporin SoPIP2;1 in Detergent Micelles and Lipid Membranes

PubMed Central

Plasencia, Inés; Survery, Sabeen; Ibragimova, Sania; Hansen, Jesper S.; Kjellbom, Per; Helix-Nielsen, Claus; Johanson, Urban; Mouritsen, Ole G.

2011-01-01

Background SoPIP2;1 constitutes one of the major integral proteins in spinach leaf plasma membranes and belongs to the aquaporin family. SoPIP2;1 is a highly permeable and selective water channel that has been successfully overexpressed and purified with high yields. In order to optimize reconstitution of the purified protein into biomimetic systems, we have here for the first time characterized the structural stability of SoPIP2;1. Methodology/Principal Finding We have characterized the protein structural stability after purification and after reconstitution into detergent micelles and proteoliposomes using circular dichroism and fluorescence spectroscopy techniques. The structure of SoPIP2;1 was analyzed either with the protein solubilized with octyl-β-D-glucopyranoside (OG) or reconstituted into lipid membranes formed by E. coli lipids, diphytanoylphosphatidylcholine (DPhPC), or reconstituted into lipid membranes formed from mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE), 1-palmitoyl-2oleoyl-phosphatidylethanolamine (POPE), 1-palmitoyl-2-oleoyl-phosphatidylserine (POPS), and ergosterol. Generally, SoPIP2;1 secondary structure was found to be predominantly α-helical in accordance with crystallographic data. The protein has a high thermal structural stability in detergent solutions, with an irreversible thermal unfolding occurring at a melting temperature of 58°C. Incorporation of the protein into lipid membranes increases the structural stability as evidenced by an increased melting temperature of up to 70°C. Conclusion/Significance The results of this study provide insights into SoPIP2;1 stability in various host membranes and suggest suitable choices of detergent and lipid composition for reconstitution of SoPIP2;1 into biomimetic membranes for biotechnological applications. PMID:21339815

Structure and stability of the spinach aquaporin SoPIP2;1 in detergent micelles and lipid membranes.

PubMed

Plasencia, Inés; Survery, Sabeen; Ibragimova, Sania; Hansen, Jesper S; Kjellbom, Per; Helix-Nielsen, Claus; Johanson, Urban; Mouritsen, Ole G

2011-02-14

SoPIP2;1 constitutes one of the major integral proteins in spinach leaf plasma membranes and belongs to the aquaporin family. SoPIP2;1 is a highly permeable and selective water channel that has been successfully overexpressed and purified with high yields. In order to optimize reconstitution of the purified protein into biomimetic systems, we have here for the first time characterized the structural stability of SoPIP2;1. We have characterized the protein structural stability after purification and after reconstitution into detergent micelles and proteoliposomes using circular dichroism and fluorescence spectroscopy techniques. The structure of SoPIP2;1 was analyzed either with the protein solubilized with octyl-β-D-glucopyranoside (OG) or reconstituted into lipid membranes formed by E. coli lipids, diphytanoylphosphatidylcholine (DPhPC), or reconstituted into lipid membranes formed from mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE), 1-palmitoyl-2oleoyl-phosphatidylethanolamine (POPE), 1-palmitoyl-2-oleoyl-phosphatidylserine (POPS), and ergosterol. Generally, SoPIP2;1 secondary structure was found to be predominantly α-helical in accordance with crystallographic data. The protein has a high thermal structural stability in detergent solutions, with an irreversible thermal unfolding occurring at a melting temperature of 58°C. Incorporation of the protein into lipid membranes increases the structural stability as evidenced by an increased melting temperature of up to 70°C. The results of this study provide insights into SoPIP2;1 stability in various host membranes and suggest suitable choices of detergent and lipid composition for reconstitution of SoPIP2;1 into biomimetic membranes for biotechnological applications.

A Crystal Structure of a Dimer of the Antibiotic Ramoplanin Illustrates Membrane Positioning and a Potential Lipid II Docking Interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamburger, J.; Hoertz, A; Lee, A

2009-01-01

The glycodepsipeptide antibiotic ramoplanin A2 is in late stage clinical development for the treatment of infections from Gram-positive pathogens, especially those that are resistant to first line antibiotics such as vancomycin. Ramoplanin A2 achieves its antibacterial effects by interfering with production of the bacterial cell wall; it indirectly inhibits the transglycosylases responsible for peptidoglycan biosynthesis by sequestering their Lipid II substrate. Lipid II recognition and sequestration occur at the interface between the extracellular environment and the bacterial membrane. Therefore, we determined the structure of ramoplanin A2 in an amphipathic environment, using detergents as membrane mimetics, to provide the most physiologicallymore » relevant structural context for mechanistic and pharmacological studies. We report here the X-ray crystal structure of ramoplanin A2 at a resolution of 1.4 {angstrom}. This structure reveals that ramoplanin A2 forms an intimate and highly amphipathic dimer and illustrates the potential means by which it interacts with bacterial target membranes. The structure also suggests a mechanism by which ramoplanin A2 recognizes its Lipid II ligand.« less

Optimization of Culture Conditions for Enhanced Growth, Lipid and Docosahexaenoic Acid (DHA) Production of Aurantiochytrium SW1 by Response Surface Methodology.

PubMed

Nazir, Yusuf; Shuib, Shuwahida; Kalil, Mohd Sahaid; Song, Yuanda; Hamid, Aidil Abdul

2018-06-11

In this study, optimization of growth, lipid and DHA production of Aurantiochytrium SW1 was carried out using response surface methodology (RSM) in optimizing initial fructose concentration, agitation speed and monosodium glutamate (MSG) concentration. Central composite design was applied as the experimental design and analysis of variance (ANOVA) was used to analyze the data. ANOVA analysis revealed that the process which adequately represented by quadratic model was significant (p < 0.0001) for all the response. All the three factors were significant (p < 0.005) in influencing the biomass and lipid data while only two factors (agitation speed and MSG) gave significant effect on DHA production (p < 0.005). The estimated optimal conditions for enhanced growth, lipid and DHA production were 70 g/L fructose, 250 rpm agitation speed and 10 g/L MSG. Consequently, the quadratic model was validated by applying the estimated optimum conditions, which confirmed the model validity where 19.0 g/L biomass, 9.13 g/L lipid and 4.75 g/L of DHA were produced. The growth, lipid and DHA were 28, 36 and 35% respectively higher than that produced in the original medium prior to optimization.

Dictyostelium discoideum Dgat2 Can Substitute for the Essential Function of Dgat1 in Triglyceride Production but Not in Ether Lipid Synthesis

PubMed Central

Du, Xiaoli; Herrfurth, Cornelia; Gottlieb, Thomas; Kawelke, Steffen; Feussner, Kristin; Rühling, Harald; Feussner, Ivo

2014-01-01

Triacylglycerol (TAG), the common energy storage molecule, is formed from diacylglycerol and a coenzyme A-activated fatty acid by the action of an acyl coenzyme A:diacylglycerol acyltransferase (DGAT). In order to conduct this step, most organisms rely on more than one enzyme. The two main candidates in Dictyostelium discoideum are Dgat1 and Dgat2. We show, by creating single and double knockout mutants, that the endoplasmic reticulum (ER)-localized Dgat1 enzyme provides the predominant activity, whereas the lipid droplet constituent Dgat2 contributes less activity. This situation may be opposite from what is seen in mammalian cells. Dictyostelium Dgat2 is specialized for the synthesis of TAG, as is the mammalian enzyme. In contrast, mammalian DGAT1 is more promiscuous regarding its substrates, producing diacylglycerol, retinyl esters, and waxes in addition to TAG. The Dictyostelium Dgat1, however, produces TAG, wax esters, and, most interestingly, also neutral ether lipids, which represent a significant constituent of lipid droplets. Ether lipids had also been found in mammalian lipid droplets, but the role of DGAT1 in their synthesis was unknown. The ability to form TAG through either Dgat1 or Dgat2 activity is essential for Dictyostelium to grow on bacteria, its natural food substrate. PMID:24562909

Influence of membrane phospholipid composition and structural organization on spontaneous lipid transfer between membranes.

PubMed

Pankov, R; Markovska, T; Antonov, P; Ivanova, L; Momchilova, A

2006-09-01

Investigations were carried out on the influence of phospholipid composition of model membranes on the processes of spontaneous lipid transfer between membranes. Acceptor vesicles were prepared from phospholipids extracted from plasma membranes of control and ras-transformed fibroblasts. Acceptor model membranes with manipulated levels of phosphatidylethanolamine (PE), sphingomyelin and phosphatidic acid were also used in the studies. Donor vesicles were prepared of phosphatidylcholine (PC) and contained two fluorescent lipid analogues, NBD-PC and N-Rh-PE, at a self-quenching concentration. Lipid transfer rate was assessed by measuring the increase of fluorescence in acceptor membranes due to transfer of fluorescent lipid analogues from quenched donor to unquenched acceptor vesicles. The results showed that spontaneous NBD-PC transfer increased upon fluidization of acceptor vesicles. In addition, elevation of PE concentration in model membranes was also accompanied by an increase of lipid transfer to all series of acceptor vesicles. The results are discussed with respect to the role of lipid composition and structural order of cellular plasma membranes in the processes of spontaneous lipid exchange between membrane bilayers.

Turning Defense into Offense: Defensin Mimetics as Novel Antibiotics Targeting Lipid II

PubMed Central

Ateh, Eugene; Oashi, Taiji; Lu, Wuyuan; Huang, Jing; Diepeveen-de Buin, Marlies; Bryant, Joseph; Breukink, Eefjan; MacKerell, Alexander D.; de Leeuw, Erik P. H.

2013-01-01

We have previously reported on the functional interaction of Lipid II with human alpha-defensins, a class of antimicrobial peptides. Lipid II is an essential precursor for bacterial cell wall biosynthesis and an ideal and validated target for natural antibiotic compounds. Using a combination of structural, functional and in silico analyses, we present here the molecular basis for defensin-Lipid II binding. Based on the complex of Lipid II with Human Neutrophil peptide-1, we could identify and characterize chemically diverse low-molecular weight compounds that mimic the interactions between HNP-1 and Lipid II. Lead compound BAS00127538 was further characterized structurally and functionally; it specifically interacts with the N-acetyl muramic acid moiety and isoprenyl tail of Lipid II, targets cell wall synthesis and was protective in an in vivo model for sepsis. For the first time, we have identified and characterized low molecular weight synthetic compounds that target Lipid II with high specificity and affinity. Optimization of these compounds may allow for their development as novel, next generation therapeutic agents for the treatment of Gram-positive pathogenic infections. PMID:24244161

Water insoluble and soluble lipids for gene delivery.

PubMed

Mahato, Ram I

2005-04-05

Among various synthetic gene carriers currently in use, liposomes composed of cationic lipids and co-lipids remain the most efficient transfection reagents. Physicochemical properties of lipid/plasmid complexes, such as cationic lipid structure, cationic lipid to co-lipid ratio, charge ratio, particle size and zeta potential have significant influence on gene expression and biodistribution. However, most cationic lipids are toxic and cationic liposomes/plasmid complexes do not disperse well inside the target tissues because of their large particle size. To overcome the problems associated with cationic lipids, we designed water soluble lipopolymers for gene delivery to various cells and tissues. This review provides a critical discussion on how the components of water insoluble and soluble lipids affect their transfection efficiency and biodistribution of lipid/plasmid complexes.

A DMPA Langmuir monolayer study: from gas to solid phase. An atomistic description by molecular dynamics Simulation.

PubMed

Giner-Casares, J J; Camacho, L; Martín-Romero, M T; Cascales, J J López

2008-03-04

In this work, a DMPA Langmuir monolayer at the air/water interface was studied by molecular dynamics simulations. Thus, an atomistic picture of a Langmuir monolayer was drawn from its expanded gas phase to its final solid condensed one. In this sense, some properties of monolayers that were traditionally poorly or even not reproduced in computer simulations, such as lipid domain formation or pressure-area per lipid isotherm, were properly reproduced in this work. Thus, the physical laws that control the lipid domain formation in the gas phase and the structure of lipid monolayers from the gas to solid condensed phase were studied. Thanks to the atomistic information provided by the molecular dynamics simulations, we were able to add valuable information to the experimental description of these processes and to access experimental data related to the lipid monolayers in their expanded phase, which is difficult or inaccessible to study by experimental techniques. In this sense, properties such as lipids head hydration and lipid structure were studied.

Zn(II)-dipicolylamine-based metallo-lipids as novel non-viral gene vectors.

PubMed

Su, Rong-Chuan; Liu, Qiang; Yi, Wen-Jing; Zhao, Zhi-Gang

2017-08-01

In this study, a series of Zn(II)-dipicolylamine (Zn-DPA) based cationic lipids bearing different hydrophobic tails (long chains, α-tocopherol, cholesterol or diosgenin) were synthesized. Structure-activity relationship (SAR) of these lipids was studied in detail by investigating the effects of several structural aspects including the type of hydrophobic tails, the chain length and saturation degree. In addition, several assays were used to study their interactions with plasmid DNA, and results reveal that these lipids could condense DNA into nanosized particles with appropriate size and zeta-potentials. MTT-based cell viability assays showed that lipoplexes 5 had low cytotoxicity. The in vitro gene transfection studies showed the hydrophobic tails clearly affected the TE, and hexadecanol-containing lipid 5b gives the best TE, which was 2.2 times higher than bPEI 25k in the presence of 10% serum. The results not only demonstrate that these lipids might be promising non-viral gene vectors, but also afford us clues for further optimization of lipidic gene delivery materials.

Functionalized lipids and surfactants for specific applications.

PubMed

Kepczynski, Mariusz; Róg, Tomasz

2016-10-01

Synthetic lipids and surfactants that do not exist in biological systems have been used for the last few decades in both basic and applied science. The most notable applications for synthetic lipids and surfactants are drug delivery, gene transfection, as reporting molecules, and as support for structural lipid biology. In this review, we describe the potential of the synergistic combination of computational and experimental methodologies to study the behavior of synthetic lipids and surfactants embedded in lipid membranes and liposomes. We focused on select cases in which molecular dynamics simulations were used to complement experimental studies aiming to understand the structure and properties of new compounds at the atomistic level. We also describe cases in which molecular dynamics simulations were used to design new synthetic lipids and surfactants, as well as emerging fields for the application of these compounds. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. Copyright © 2016 Elsevier B.V. All rights reserved.

Interaction of lysozyme with a tear film lipid layer model: A molecular dynamics simulation study.

PubMed

Wizert, Alicja; Iskander, D Robert; Cwiklik, Lukasz

2017-12-01

The tear film is a thin multilayered structure covering the cornea. Its outermost layer is a lipid film underneath of which resides on an aqueous layer. This tear film lipid layer (TFLL) is itself a complex structure, formed by both polar and nonpolar lipids. It was recently suggested that due to tear film dynamics, TFLL contains inhomogeneities in the form of polar lipid aggregates. The aqueous phase of tear film contains lachrymal-origin proteins, whereby lysozyme is the most abundant. These proteins can alter TFLL properties, mainly by reducing its surface tension. However, a detailed nature of protein-lipid interactions in tear film is not known. We investigate the interactions of lysozyme with TFLL in molecular details by employing coarse-grained molecular dynamics simulations. We demonstrate that lysozyme, due to lateral restructuring of TFLL, is able to penetrate the tear lipid film embedded in inverse micellar aggregates. Copyright © 2017 Elsevier B.V. All rights reserved.

Understanding the mechanisms of lipid extraction from microalga Chlamydomonas reinhardtii after electrical field solicitations and mechanical stress within a microfluidic device.

PubMed

Bensalem, Sakina; Lopes, Filipa; Bodénès, Pierre; Pareau, Dominique; Français, Olivier; Le Pioufle, Bruno

2018-06-01

One way envisioned to overcome part of the issues biodiesel production encounters today is to develop a simple, economically viable and eco-friendly process for the extraction of lipids from microalgae. This study investigates the lipid extraction efficiency from the microalga Chlamydomonas reinhardtii as well as the underlying mechanisms. We propose a new methodology combining a pulsed electric field (PEF) application and mechanical stresses as a pretreatment to improve lipid extraction with solvents. Cells enriched in lipids are therefore submitted to electric field pulses creating pores on the cell membrane and then subjected to a mechanical stress by applying cyclic pressures on the cell wall (using a microfluidic device). Results showed an increase in lipid extraction when cells were pretreated by the combination of both methods. Microscopic observations showed that both pretreatments affect the cell structure. Finally, the dependency of solvent lipid extraction efficiency with the cell wall structure is discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

A plural role for lipids in motor neuron diseases: energy, signaling and structure

PubMed Central

Schmitt, Florent; Hussain, Ghulam; Dupuis, Luc; Loeffler, Jean-Philippe; Henriques, Alexandre

2013-01-01

Motor neuron diseases (MNDs) are characterized by selective death of motor neurons and include mainly adult-onset amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). Neurodegeneration is not the single pathogenic event occurring during disease progression. There are multiple lines of evidence for the existence of defects in lipid metabolism at peripheral level. For instance, hypermetabolism is well characterized in ALS, and dyslipidemia correlates with better prognosis in patients. Lipid metabolism plays also a role in other MNDs. In SMA, misuse of lipids as energetic nutrients is described in patients and in related animal models. The composition of structural lipids in the central nervous system is modified, with repercussion on membrane fluidity and on cell signaling mediated by bioactive lipids. Here, we review the main epidemiologic and mechanistic findings that link alterations of lipid metabolism and motor neuron degeneration, and we discuss the rationale of targeting these modifications for therapeutic management of MNDs. PMID:24600344

A Remarkably Simple Class of Imidazolium-Based Lipids and Their Biological Properties.

PubMed

Wang, Da; Richter, Christian; Rühling, Andreas; Drücker, Patrick; Siegmund, Daniel; Metzler-Nolte, Nils; Glorius, Frank; Galla, Hans-Joachim

2015-10-19

A series of imidazolium salts bearing two alkyl chains in the backbone of the imidazolium core were synthesized, resembling the structure of lipids. Their antibacterial activity and cytotoxicity were evaluated using Gram-positive and Gram-negative bacteria and eukaryotic cell lines including tumor cells. It is shown that the length of alkyl chains in the backbone is vital for the antibiofilm activities of these lipid-mimicking components. In addition to their biological activity, their surface activity and their membrane interactions are shown by film balance and quartz crystal microbalance (QCM) measurements. The structure-activity relationship indicates that the distinctive chemical structure contributes considerably to the biological activities of this novel class of lipids. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Plasma membrane association facilitates conformational changes in the Marburg virus protein VP40 dimer.

PubMed

Bhattarai, Nisha; Gc, Jeevan B; Gerstman, Bernard S; Stahelin, Robert V; Chapagain, Prem P

2017-04-26

Filovirus infections cause hemorrhagic fever in humans and non-human primates that often results in high fatality rates. The Marburg virus is a lipid-enveloped virus from the Filoviridae family and is closely related to the Ebola virus. The viral matrix layer underneath the lipid envelope is formed by the matrix protein VP40 (VP40), which is also involved in other functions during the viral life-cycle. As in the Ebola virus VP40 (eVP40), the recently determined X-ray crystal structure of the Marburg virus VP40 (mVP40) features loops containing cationic residues that form a lipid binding basic patch. However, the mVP40 basic patch is significantly flatter with a more extended surface than in eVP40, suggesting the possibility of differences in the plasma membrane interactions and phospholipid specificity between the VP40 dimers. In this paper, we report on molecular dynamics simulations that investigate the roles of various residues and lipid types in PM association as well as the conformational changes of the mVP40 dimer facilitated by membrane association. We compared the structural changes of the mVP40 dimer with the mVP40 dimer in both lipid free and membrane associated conditions. Despite the significant structural differences in the crystal structure, the Marburg VP40 dimer is found to adopt a configuration very similar to the Ebola VP40 dimer after associating with the membrane. This conformational rearrangement upon lipid binding allows Marburg VP40 to localize and stabilize at the membrane surface in a manner similar to the Ebola VP40 dimer. Consideration of the structural information in its lipid-interacting condition may be important in targeting mVP40 for novel drugs to inhibit viral budding from the plasma membrane.

Structural organisation and lipid composition of the epicuticular accessory layer of infective larvae of Trichinella spiralis.

PubMed

Gounaris, K; Smith, V P; Selkirk, M E

1996-05-22

The epicuticle of infective larvae of Trichinella spiralis represents the interface between this intracellular nematode parasite and the cytosol of mammalian skeletal muscle. The macromolecular structures that make up the epicuticle were studied by freeze-fracture electron microscopy and compositional analysis. Three fracture planes were observed: one with a typical plasma membrane-type bilayer organisation which was overlaid by two extended layers of lipid in an inverted cylindrical configuration. This overall structure remained unchanged in response to variations in temperature between 20 degrees C and 45 degrees C. The lipid cylinders were on average 6.8 nm in diameter, with randomly-associated particles that were not dissociated by high-salt treatment, indicative of hydrophobically associated proteins. The majority of the lipids were non-polar, consisting of cholesterol, cholesterol esters, mono- and tri-glycerides, and free fatty acids. Three major classes of phospholipids were identified: phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. Total lipid extracts did not adopt an inverted cylindrical or micellar configuration on isolation, but formed flat sheets of lamellae as did the purified polar and non-polar fractions of the lipids. Isolated lipids did not undergo thermally-induced polymorphism between 20 degrees C and 60 degrees C and there was no pH dependency of the structures adopted. The fatty acid saturation levels of the phospholipids were compatible with the observation that they did not form polymorphic structures on isolation. We suggest that this unusual configuration is probably stabilised by the associated (glyco)proteins and may be required for selective permeation of nutrients from the host cell cytosol and/or for maintaining the high curvature of the parasite within the cell.

Structure-reactivity relationship in the oxidation of carotenoid pigments of the pepper (Capsicum annuum L.).

PubMed

Pérez-Gálvez, A; Mínguez-Mosquera, M I

2001-10-01

The relationship between the degradation rate and structure of each pigment of the pepper carotenoid profile was studied in mixtures of dehydrated fruit with lipid substrates of differing degrees of unsaturation and in different proportions (20 and 40%). The differences in structural nature of the carotenoids present in the pepper fruit produce a variable rate of oxidation, resulting in nonuniform degradation. The yellow xanthophylls and beta-carotene have the highest rates of oxidation, with the ketocarotenoids and violaxanthin degrading at lower rates. Autoxidation is greater or lesser depending on the functional groups, which stabilize the radical intermediaries of the reaction. The behavior of capsanthin and capsorubin is that expected of carotenoids having structures that include keto groups: a markedly greater stability to autoxidation processes. This increases their antioxidant capacity, adding to their beneficial impact by reducing the proliferation of radical processes, which are detrimental to health.

Role of Conserved Proline Residues in Human Apolipoprotein A-IV Structure and Function*

PubMed Central

Deng, Xiaodi; Walker, Ryan G.; Morris, Jamie; Davidson, W. Sean; Thompson, Thomas B.

2015-01-01

Apolipoprotein (apo)A-IV is a lipid emulsifying protein linked to a range of protective roles in obesity, diabetes, and cardiovascular disease. It exists in several states in plasma including lipid-bound in HDL and chylomicrons and as monomeric and dimeric lipid-free/poor forms. Our recent x-ray crystal structure of the central domain of apoA-IV shows that it adopts an elongated helical structure that dimerizes via two long reciprocating helices. A striking feature is the alignment of conserved proline residues across the dimer interface. We speculated that this plays important roles in the structure of the lipid-free protein and its ability to bind lipid. Here we show that the systematic conversion of these prolines to alanine increased the thermodynamic stability of apoA-IV and its propensity to oligomerize. Despite the structural stabilization, we noted an increase in the ability to bind and reorganize lipids and to promote cholesterol efflux from cells. The novel properties of these mutants allowed us to isolate the first trimeric form of an exchangeable apolipoprotein and characterize it by small-angle x-ray scattering and chemical cross-linking. The results suggest that the reciprocating helix interaction is a common feature of all apoA-IV oligomers. We propose a model of how self-association of apoA-IV can result in spherical lipoprotein particles, a model that may have broader applications to other exchangeable apolipoprotein family members. PMID:25733664

Engineering Aspergillus oryzae A-4 through the Chromosomal Insertion of Foreign Cellulase Expression Cassette to Improve Conversion of Cellulosic Biomass into Lipids

PubMed Central

Shen, Qi; Ma, Junwei; Fu, Jianrong; Zhao, Yuhua

2014-01-01

A genetic modification scheme was designed for Aspergillus oryzae A-4, a natural cellulosic lipids producer, to enhance its lipid production from biomass by putting the spotlight on improving cellulase secretion. Four cellulase genes were separately expressed in A-4 under the control of hlyA promoter, with the help of the successful development of a chromosomal genetic manipulation system. Comparison of cellulase activities of PCR-positive transformants showed that these transformants integrated with celA gene and with celC gene had significantly (p<0.05) higher average FPAase activities than those strains integrated with celB gene and with celD gene. Through the assessment of cellulosic lipids accumulating abilities, celA transformant A2-2 and celC transformant D1-B1 were isolated as promising candidates, which could yield 101%–133% and 35.22%–59.57% higher amount of lipids than the reference strain A-4 (WT) under submerged (SmF) conditions and solid-state (SSF) conditions, respectively. Variability in metabolism associated to the introduction of cellulase gene in A2-2 and D1-B1 was subsequently investigated. It was noted that cellulase expression repressed biomass formation but enhanced lipid accumulation; whereas the inhibitory effect on cell growth would be shielded during cellulosic lipids production owing to the essential role of cellulase in substrate utilization. Different metabolic profiles also existed between A2-2 and D1-B1, which could be attributed to not only different transgene but also biological impacts of different integration. Overall, both simultaneous saccharification and lipid accumulation were enhanced in A2-2 and D1-B1, resulting in efficient conversion of cellulose into lipids. A regulation of cellulase secretion in natural cellulosic lipids producers could be a possible strategy to enhance its lipid production from lignocellulosic biomass. PMID:25251435

Engineering Aspergillus oryzae A-4 through the chromosomal insertion of foreign cellulase expression cassette to improve conversion of cellulosic biomass into lipids.

PubMed

Lin, Hui; Wang, Qun; Shen, Qi; Ma, Junwei; Fu, Jianrong; Zhao, Yuhua

2014-01-01

A genetic modification scheme was designed for Aspergillus oryzae A-4, a natural cellulosic lipids producer, to enhance its lipid production from biomass by putting the spotlight on improving cellulase secretion. Four cellulase genes were separately expressed in A-4 under the control of hlyA promoter, with the help of the successful development of a chromosomal genetic manipulation system. Comparison of cellulase activities of PCR-positive transformants showed that these transformants integrated with celA gene and with celC gene had significantly (p<0.05) higher average FPAase activities than those strains integrated with celB gene and with celD gene. Through the assessment of cellulosic lipids accumulating abilities, celA transformant A2-2 and celC transformant D1-B1 were isolated as promising candidates, which could yield 101%-133% and 35.22%-59.57% higher amount of lipids than the reference strain A-4 (WT) under submerged (SmF) conditions and solid-state (SSF) conditions, respectively. Variability in metabolism associated to the introduction of cellulase gene in A2-2 and D1-B1 was subsequently investigated. It was noted that cellulase expression repressed biomass formation but enhanced lipid accumulation; whereas the inhibitory effect on cell growth would be shielded during cellulosic lipids production owing to the essential role of cellulase in substrate utilization. Different metabolic profiles also existed between A2-2 and D1-B1, which could be attributed to not only different transgene but also biological impacts of different integration. Overall, both simultaneous saccharification and lipid accumulation were enhanced in A2-2 and D1-B1, resulting in efficient conversion of cellulose into lipids. A regulation of cellulase secretion in natural cellulosic lipids producers could be a possible strategy to enhance its lipid production from lignocellulosic biomass.

Carbohydrate and lipid spectroscopic molecular structures of different alfalfa hay and their relationship with nutrient availability in ruminants

PubMed Central

Yari, Mojtaba; Valizadeh, Reza; Nnaserian, Abbas Ali; Jonker, Arjan; Yu, Peiqiang

2017-01-01

Objective This study was conducted to determine molecular structures related to carbohydrates and lipid in alfalfa hay cut at early bud, late bud and early flower and in the afternoon and next morning using Fourier transform infrared spectroscopy (FT/IR) and to determine their relationship with alfalfa hay nutrient profile and availability in ruminants. Methods Chemical composition analysis, carbohydrate fractionation, in situ ruminal degradability, and DVE/OEB model were used to measure nutrient profile and availability of alfalfa hay. Univariate analysis, hierarchical cluster analysis (CLA) and principal components analysis (PCA) were conducted to identify FT/IR spectra differences. Results The FT/IR non-structural carbohydrate (NSCHO) to total carbohydrates and NSCHO to structural carbohydrate ratios decreased (p<0.05), while lignin to NSCHO and lipid CH3 symmetric to CH2 symmetric ratios increased with advancing maturity (p<0.05). The FT/IR spectra related to structural carbohydrates, lignin and lipids were distinguished for alfalfa hay at three maturities by PCA and CLA, while FT/IR molecular structures related to carbohydrates and lipids were similar between alfalfa hay cut in the morning and afternoon when analyzed by PCA and CLA analysis. Positive correlations were found for FT/IR NSCHO to total carbohydrate and NSCHO to structural carbohydrate ratios with non-fiber carbohydrate (by wet chemistry), ruminal fast and intermediately degradable carbohydrate fractions and total ruminal degradability of carbohydrates and predicted intestinal nutrient availability in dairy cows (r≥0.60; p<0.05) whereas FT/IR lignin to NSCHO and CH3 to CH2 symmetric stretching ratio had negative correlation with predicted ruminal and intestinal nutrient availability of alfalfa hay in dairy cows (r≥−0.60; p<0.05). Conclusion FT/IR carbohydrate and lipid molecular structures in alfalfa hay changed with advancing maturity from early bud to early flower, but not during the day, and these molecular structures correlated with predicted nutrient supply of alfalfa hay in ruminants. PMID:28335093

The effects of abscisic acid, salicylic acid and jasmonic acid on lipid accumulation in two freshwater Chlorella strains.

PubMed

Wu, Guanxun; Gao, Zhengquan; Du, Huanmin; Lin, Bin; Yan, Yuchen; Li, Guoqiang; Guo, Yanyun; Fu, Shenggui; Wei, Gongxiang; Wang, Miaomiao; Cui, Meng; Meng, Chunxiao

2018-03-27

Sustainable renewable energy is being hotly debated globally because the continued use of finite fossil fuels is now widely recognized as being unsustainable. Microalgae potentially offer great opportunities for resolving this challenge. Abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) are involved in regulating many physiological properties and have been widely used in higher plants. To test if phytohormones have an impact on accumulating lipid for microalgae, ABA, JA and SA were used to induce two Chlorella strains in the present study. The results showed 1.0 mg/L ABA, 10 mg/L SA, and 0.5 mg/L JA, led strain C. vulgaris ZF strain to produce a 45%, 42% and 49% lipid content that was 1.8-, 1.7- and 2.0-fold that of controls, respectively. For FACHB 31 (number 31 of the Freshwater Algae Culture Collection at the Institute of Hydrobiology, Chinese Academy of Sciences), the addition of 1.0 mg/L ABA, 10 mg/L SA, and 0.5 mg/L, JA produced 33%, 30% and 38% lipid content, which was 1.8-, 1.6- and 2.1-fold that of controls, respectively. As for lipid productivity, 1.0 mg/L ABA increased the lipid productivity of C. vulgaris ZF strain and FACHB-31 by 123% and 44%; 10 mg/L SA enhanced lipid productivity by 100% and 33%; the best elicitor, 0.5 mg/L JA, augmented lipid productivity by 127% and 75% compared to that of controls, respectively. The results above suggest that the three phytohormones at physiological concentrations play crucial roles in inducing lipid accumulation in Chlorella.

Interaction of tau protein with model lipid membranes induces tau structural compaction and membrane disruption

PubMed Central

Jones, Emmalee M.; Dubey, Manish; Camp, Phillip J.; Vernon, Briana C.; Biernat, Jacek; Mandelkow, Eckhard; Majewski, Jaroslaw; Chi, Eva Y.

2012-01-01

The misfolding and aggregation of the intrinsically disordered, microtubule-associated tau protein into neurofibrillary tangles is implicated in the pathogenesis of Alzheimer's disease. However, the mechanisms of tau aggregation and toxicity remain unknown. Recent work has shown that lipid membrane can induce tau aggregation and that membrane permeabilization may serve as a pathway by which protein aggregates exert toxicity, suggesting that the plasma membrane may play dual roles in tau pathology. This prompted our investigation to assess tau's propensity to interact with membranes and to elucidate the mutually disruptive structural perturbations the interactions induce in both tau and the membrane. We show that although highly charged and soluble, the full-length tau (hTau40) is also highly surface active, selectively inserts into anionic DMPG lipid monolayers and induces membrane morphological changes. To resolve molecular-scale structural details of hTau40 associated with lipid membranes, X-ray and neutron scattering techniques are utilized. X-ray reflectivity indicates hTau40's presence underneath a DMPG monolayer and penetration into the lipid headgroups and tailgroups, whereas grazing incidence X-ray diffraction shows that hTau40 insertion disrupts lipid packing. Moreover, both air/water and DMPG lipid membrane interfaces induce the disordered hTau40 to partially adopt a more compact conformation with density similar to that of a folded protein. Neutron reflectivity shows that tau completely disrupts supported DMPG bilayers while leaving the neutral DPPC bilayer intact. Our results show that hTau40's strong interaction with anionic lipids induces tau structural compaction and membrane disruption, suggesting possible membrane-based mechanisms of tau aggregation and toxicity in neurodegenerative diseases. PMID:22401494

Membranes linked by trans-SNARE complexes require lipids prone to non-bilayer structure for progression to fusion.

PubMed

Zick, Michael; Stroupe, Christopher; Orr, Amy; Douville, Deborah; Wickner, William T

2014-01-01

Like other intracellular fusion events, the homotypic fusion of yeast vacuoles requires a Rab GTPase, a large Rab effector complex, SNARE proteins which can form a 4-helical bundle, and the SNARE disassembly chaperones Sec17p and Sec18p. In addition to these proteins, specific vacuole lipids are required for efficient fusion in vivo and with the purified organelle. Reconstitution of vacuole fusion with all purified components reveals that high SNARE levels can mask the requirement for a complex mixture of vacuole lipids. At lower, more physiological SNARE levels, neutral lipids with small headgroups that tend to form non-bilayer structures (phosphatidylethanolamine, diacylglycerol, and ergosterol) are essential. Membranes without these three lipids can dock and complete trans-SNARE pairing but cannot rearrange their lipids for fusion. DOI: http://dx.doi.org/10.7554/eLife.01879.001.

Lipids: From Chemical Structures, Biosynthesis, and Analyses to Industrial Applications.

PubMed

Li-Beisson, Yonghua; Nakamura, Yuki; Harwood, John

2016-01-01

Lipids are one of the major subcellular components, and play numerous essential functions. As well as their physiological roles, oils stored in biomass are useful commodities for a variety of biotechnological applications including food, chemical feedstocks, and fuel. Due to their agronomic as well as economic and societal importance, lipids have historically been subjected to intensive studies. Major current efforts are to increase the energy density of cell biomass, and/or create designer oils suitable for specific applications. This chapter covers some basic aspects of what one needs to know about lipids: definition, structure, function, metabolism and focus is also given on the development of modern lipid analytical tools and major current engineering approaches for biotechnological applications. This introductory chapter is intended to serve as a primer for all subsequent chapters in this book outlining current development in specific areas of lipids and their metabolism.

Complex biomembrane mimetics on the sub-nanometer scale

DOE PAGES

Heberle, Frederick A.; Pabst, Georg

2017-07-17

Biomimetic lipid vesicles are indispensable tools for gaining insight into the biophysics of cell physiology on the molecular level. The level of complexity of these model systems has steadily increased, and now spans from domain forming lipid mixtures to asymmetric lipid bilayers. We review recent progress in the development and application of elastic neutron and X-ray scattering techniques for studying these systems in situ and under physiologically relevant conditions on the nanometer to sub-nanometer length scales. Particularly we focus on: (i) structural details of coexisting liquid-ordered and liquid-disordered domains, including their thickness and lipid packing mismatch as a function ofmore » a size transition from nanoscopic to macroscopic domains; (ii) membrane-mediated protein partitioning into lipid domains; (iii) the role of the aqueous medium in tuning interactions between membranes and domains; and (iv) leaflet specific structure in asymmetric bilayers and passive lipid flip-flop.« less

Complex biomembrane mimetics on the sub-nanometer scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heberle, Frederick A.; Pabst, Georg

Biomimetic lipid vesicles are indispensable tools for gaining insight into the biophysics of cell physiology on the molecular level. The level of complexity of these model systems has steadily increased, and now spans from domain forming lipid mixtures to asymmetric lipid bilayers. We review recent progress in the development and application of elastic neutron and X-ray scattering techniques for studying these systems in situ and under physiologically relevant conditions on the nanometer to sub-nanometer length scales. Particularly we focus on: (i) structural details of coexisting liquid-ordered and liquid-disordered domains, including their thickness and lipid packing mismatch as a function ofmore » a size transition from nanoscopic to macroscopic domains; (ii) membrane-mediated protein partitioning into lipid domains; (iii) the role of the aqueous medium in tuning interactions between membranes and domains; and (iv) leaflet specific structure in asymmetric bilayers and passive lipid flip-flop.« less

Synthesis and Characterization of Novel Anchorlipids for Tethered Bilayer Lipid Membranes.

PubMed

Andersson, Jakob; Knobloch, Jacqueline J; Perkins, Michael V; Holt, Stephen A; Köper, Ingo

2017-05-09

Tethered bilayer lipid membranes are versatile solid-supported model membrane systems. Core to these systems is an anchorlipid that covalently links a lipid bilayer to a support. The molecular structure of these lipids can have a significant impact on the properties of the resulting bilayer. Here, the synthesis of anchorlipids containing ester groups in the tethering part is described. The lipids are used to form bilayer membranes, and the resulting structures are compared with membranes formed using conventional anchorlipids or sparsely tethered membranes. All membranes showed good electrical sealing properties; the disulphide-terminated anchorlipids could be used in a sparsely tethered system without significantly reducing the sealing properties of the lipid bilayers. The sparsely tethered systems also allowed for higher ion transport across the membrane, which is in good correlation with higher hydration of the spacer region as seen by neutron scattering.

Linking lipid architecture to bilayer structure and mechanics using self-consistent field modelling.

PubMed

Pera, H; Kleijn, J M; Leermakers, F A M

2014-02-14

To understand how lipid architecture determines the lipid bilayer structure and its mechanics, we implement a molecularly detailed model that uses the self-consistent field theory. This numerical model accurately predicts parameters such as Helfrichs mean and Gaussian bending modulus kc and k̄ and the preferred monolayer curvature J(0)(m), and also delivers structural membrane properties like the core thickness, and head group position and orientation. We studied how these mechanical parameters vary with system variations, such as lipid tail length, membrane composition, and those parameters that control the lipid tail and head group solvent quality. For the membrane composition, negatively charged phosphatidylglycerol (PG) or zwitterionic, phosphatidylcholine (PC), and -ethanolamine (PE) lipids were used. In line with experimental findings, we find that the values of kc and the area compression modulus kA are always positive. They respond similarly to parameters that affect the core thickness, but differently to parameters that affect the head group properties. We found that the trends for k̄ and J(0)(m) can be rationalised by the concept of Israelachivili's surfactant packing parameter, and that both k̄ and J(0)(m) change sign with relevant parameter changes. Although typically k̄ < 0, membranes can form stable cubic phases when the Gaussian bending modulus becomes positive, which occurs with membranes composed of PC lipids with long tails. Similarly, negative monolayer curvatures appear when a small head group such as PE is combined with long lipid tails, which hints towards the stability of inverse hexagonal phases at the cost of the bilayer topology. To prevent the destabilisation of bilayers, PG lipids can be mixed into these PC or PE lipid membranes. Progressive loading of bilayers with PG lipids lead to highly charged membranes, resulting in J(0)(m) > 0, especially at low ionic strengths. We anticipate that these changes lead to unstable membranes as these become vulnerable to pore formation or disintegration into lipid disks.

Low trans structured fat from flaxseed oil improves plasma and hepatic lipid metabolism in apo E(-/-) mice.

PubMed

Cho, Yun-Young; Kwon, Eun-Young; Kim, Hye-Jin; Park, Yong-Bok; Lee, Ki-Teak; Park, Taesun; Choi, Myung-Sook

2009-07-01

The objective of this study was to explicate the effects of feeding low trans structured fat from flaxseed oil (LF) on plasma and hepatic lipid metabolism involved in apo E(-/-) mice. The animals were fed a commercial shortening (CS), commercial low trans fat (CL) and LF diet based on AIN-76 diet (10% fat) for 12 weeks. LF supplementation exerted a significant suppression in hepatic lipid accumulation with the concomitant decrease in liver weight. The LF significantly lowered plasma total cholesterol and free fatty acid whereas it significantly increased HDL-C concentration and the HDL-C/total-C ratio compared to the CS group. Reduction of hepatic lipid levels in the LF group was related with the suppression of hepatic enzyme activities for fatty acid and triglyceride synthesis, and cholesterol regulating enzyme activity compared to the CS and CL groups. Accordingly, low trans structured fat from flaxseed oil is highly effective for improving hyperlipidemia and hepatic lipid accumulation in apo E(-/-) mice.

Entropic Anomaly Observed in Lipid Polymorphisms Induced by Surfactant Peptide SP-B(1-25).

PubMed

Tran, Nhi; Kurian, Justin; Bhatt, Avni; McKenna, Robert; Long, Joanna R

2017-10-05

The N-terminal 25 amino-acid residues of pulmonary surfactant protein B (SP-B 1-25 ) induces unusual lipid polymorphisms in a model lipid system, 4:1 DPPC/POPG, mirroring the lipid composition of native pulmonary surfactant. It is widely suggested that SP-B 1-25 -induced lipid polymorphisms within the alveolar aqueous subphase provide a structural platform for rapid lipid adsorption to the air-water interface. Here, we characterize in detail the phase behavior of DPPC and POPG in hydrated lipid assemblies containing therapeutic levels of SP-B 1-25 using 2 H and 31 P solid state NMR spectroscopy. The appearance of a previously observed isotropic lipid phase is found to be highly dependent on the thermal cycling of the samples. Slow heating of frozen samples leads to phase separation of DPPC into a lamellar phase whereas POPG lipids interact with the peptide to form an isotropic phase at physiologic temperature. Rapid heating of frozen samples to room temperature leads to strongly isotropic phase behavior for both DPPC and POPG lipids, with DPPC in exchange between isotropic and interdigitated phases. 31 P T 2 relaxation times confirm the isotropic phase to be consistent with a lipid cubic phase. The observed phases exhibit thermal stability up to physiologic temperature (37 °C) and are consistent with the formation of a ripple phase containing a large number of peptide-induced membrane structural defects enabling rapid transit of lipids between lipid lamellae. The coexistance of a lipid cubic phase with interdigitated lipids suggests a specific role for the highly conserved N-terminus of SP-B in stabilizing this unusual lipid polymorphism.

LipidMatch: an automated workflow for rule-based lipid identification using untargeted high-resolution tandem mass spectrometry data.

PubMed

Koelmel, Jeremy P; Kroeger, Nicholas M; Ulmer, Candice Z; Bowden, John A; Patterson, Rainey E; Cochran, Jason A; Beecher, Christopher W W; Garrett, Timothy J; Yost, Richard A

2017-07-10

Lipids are ubiquitous and serve numerous biological functions; thus lipids have been shown to have great potential as candidates for elucidating biomarkers and pathway perturbations associated with disease. Methods expanding coverage of the lipidome increase the likelihood of biomarker discovery and could lead to more comprehensive understanding of disease etiology. We introduce LipidMatch, an R-based tool for lipid identification for liquid chromatography tandem mass spectrometry workflows. LipidMatch currently has over 250,000 lipid species spanning 56 lipid types contained in in silico fragmentation libraries. Unique fragmentation libraries, compared to other open source software, include oxidized lipids, bile acids, sphingosines, and previously uncharacterized adducts, including ammoniated cardiolipins. LipidMatch uses rule-based identification. For each lipid type, the user can select which fragments must be observed for identification. Rule-based identification allows for correct annotation of lipids based on the fragments observed, unlike typical identification based solely on spectral similarity scores, where over-reporting structural details that are not conferred by fragmentation data is common. Another unique feature of LipidMatch is ranking lipid identifications for a given feature by the sum of fragment intensities. For each lipid candidate, the intensities of experimental fragments with exact mass matches to expected in silico fragments are summed. The lipid identifications with the greatest summed intensity using this ranking algorithm were comparable to other lipid identification software annotations, MS-DIAL and Greazy. For example, for features with identifications from all 3 software, 92% of LipidMatch identifications by fatty acyl constituents were corroborated by at least one other software in positive mode and 98% in negative ion mode. LipidMatch allows users to annotate lipids across a wide range of high resolution tandem mass spectrometry experiments, including imaging experiments, direct infusion experiments, and experiments employing liquid chromatography. LipidMatch leverages the most extensive in silico fragmentation libraries of freely available software. When integrated into a larger lipidomics workflow, LipidMatch may increase the probability of finding lipid-based biomarkers and determining etiology of disease by covering a greater portion of the lipidome and using annotation which does not over-report biologically relevant structural details of identified lipid molecules.

Identification of conserved lipid/detergent-binding sites in a high-resolution structure of the membrane protein cytochrome c oxidase

PubMed Central

Qin, Ling; Hiser, Carrie; Mulichak, Anne; Garavito, R. Michael; Ferguson-Miller, Shelagh

2006-01-01

Well ordered reproducible crystals of cytochrome c oxidase (CcO) from Rhodobacter sphaeroides yield a previously unreported structure at 2.0 Å resolution that contains the two catalytic subunits and a number of alkyl chains of lipids and detergents. Comparison with crystal structures of other bacterial and mammalian CcOs reveals that the positions occupied by native membrane lipids and detergent substitutes are highly conserved, along with amino acid residues in their vicinity, suggesting a more prevalent and specific role of lipid in membrane protein structure than often envisioned. Well defined detergent head groups (maltose) are found associated with aromatic residues in a manner similar to phospholipid head groups, likely contributing to the success of alkyl glycoside detergents in supporting membrane protein activity and crystallizability. Other significant features of this structure include the following: finding of a previously unreported crystal contact mediated by cadmium and an engineered histidine tag; documentation of the unique His–Tyr covalent linkage close to the active site; remarkable conservation of a chain of waters in one proton pathway (D-path); and discovery of an inhibitory cadmium-binding site at the entrance to another proton path (K-path). These observations provide important insight into CcO structure and mechanism, as well as the significance of bound lipid in membrane proteins. PMID:17050688

Lipid-based nanotubes as functional architectures with embedded fluorescence and recognition capabilities.

PubMed

John, George; Mason, Megan; Ajayan, Pulickel M; Dordick, Jonathan S

2004-11-24

A limited combinatorial strategy was used to synthesize a small library of soft lipid-based materials ranging from structurally unordered fibers to highly uniform nanotubes. The latter nanotubes are comprised of a bilayer structure with interdigitated alkyl chains associated through hydrophobic interactions. These tubes contain accessible 2,6-diaminopyridine linkers that can interact with thymidine and related nucleosides through multipoint hydrogen bonding, thereby quenching the intrinsic fluorescence of the aromatic linker. These results are the first example of a systematic strategy to design functional lipid nanotubes with precise structural and functional features.

Identifying the Interaction of Vancomycin With Novel pH-Responsive Lipids as Antibacterial Biomaterials Via Accelerated Molecular Dynamics and Binding Free Energy Calculations.

PubMed

Ahmed, Shaimaa; Vepuri, Suresh B; Jadhav, Mahantesh; Kalhapure, Rahul S; Govender, Thirumala

2018-06-01

Nano-drug delivery systems have proven to be an efficient formulation tool to overcome the challenges with current antibiotics therapy and resistance. A series of pH-responsive lipid molecules were designed and synthesized for future liposomal formulation as a nano-drug delivery system for vancomycin at the infection site. The structures of these lipids differ from each other in respect of hydrocarbon tails: Lipid1, 2, 3 and 4 have stearic, oleic, linoleic, and linolenic acid hydrocarbon chains, respectively. The impact of variation in the hydrocarbon chain in the lipid structure on drug encapsulation and release profile, as well as mode of drug interaction, was investigated using molecular modeling analyses. A wide range of computational tools, including accelerated molecular dynamics, normal molecular dynamics, binding free energy calculations and principle component analysis, were applied to provide comprehensive insight into the interaction landscape between vancomycin and the designed lipid molecules. Interestingly, both MM-GBSA and MM-PBSA binding affinity calculations using normal molecular dynamics and accelerated molecular dynamics trajectories showed a very consistent trend, where the order of binding affinity towards vancomycin was lipid4 > lipid1 > lipid2 > lipid3. From both normal molecular dynamics and accelerated molecular dynamics, the interaction of lipid3 with vancomycin is demonstrated to be the weakest (∆G binding  = -2.17 and -11.57, for normal molecular dynamics and accelerated molecular dynamics, respectively) when compared to other complexes. We believe that the degree of unsaturation of the hydrocarbon chain in the lipid molecules may impact on the overall conformational behavior, interaction mode and encapsulation (wrapping) of the lipid molecules around the vancomycin molecule. This thorough computational analysis prior to the experimental investigation is a valuable approach to guide for predicting the encapsulation ability, drug release and further development of novel liposome-based pH-responsive nano-drug delivery system with refined structural and chemical features of potential lipid molecule for formulation development.

Synthetic biology for microbial production of lipid-based biofuels.

PubMed

d'Espaux, Leo; Mendez-Perez, Daniel; Li, Rachel; Keasling, Jay D

2015-12-01

The risks of maintaining current CO2 emission trends have led to interest in producing biofuels using engineered microbes. Microbial biofuels reduce emissions because CO2 produced by fuel combustion is offset by CO2 captured by growing biomass, which is later used as feedstock for biofuel fermentation. Hydrocarbons found in petroleum fuels share striking similarity with biological lipids. Here we review synthetic metabolic pathways based on fatty acid and isoprenoid metabolism to produce alkanes and other molecules suitable as biofuels. We further discuss engineering strategies to optimize engineered biosynthetic routes, as well as the potential of synthetic biology for sustainable manufacturing. Published by Elsevier Ltd.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Shih-Ching; Lo, Shih-Yen; Graduate Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan

Research highlights: {yields} Lipid rafts are known to play an important role in virus entry and virus assembly of many viruses. {yields} However, HCV is the first example of the association of lipid raft with viral RNA replication. {yields} Our results in this manuscript demonstrate that purified HCV RCs with associated lipid raft membrane appeared as distinct particles of around 0.7 um under EM and AFM. {yields} Knockdown of proteins associated with lipid raft suppressed the HCV replication and reduced the number of these particles. {yields} To our knowledge, structures of HCV RCs were demonstrated at its first time inmore » this manuscript. -- Abstract: Hepatitis C viral RNA synthesis has been demonstrated to occur on a lipid raft membrane structure. Lipid raft membrane fraction purified by membrane flotation analysis was observed using transmission electron microscopy and atomic force microscopy. Particles around 0.7 um in size were found in lipid raft membrane fraction purified from hepatitis C virus (HCV) replicon but not their parental HuH7 cells. HCV NS5A protein was associated with these specialized particles. After several cycles of freezing-thawing, these particles would fuse into larger sizes up to 10 um. Knockdown of seven proteins associated with lipid raft (VAPA, COPG, RAB18, COMT, CDC42, DPP4, and KDELR2) of HCV replicon cells reduced the observed number of these particles and suppressed the HCV replication. Results in this study indicated that HCV replication complexes with associated lipid raft membrane form distinct particle structures of around 0.7 um as observed from transmission electron microscopy and atomic force microscopy.« less

The Fluid-Mosaic Model of Membrane Structure: still relevant to understanding the structure, function and dynamics of biological membranes after more than 40 years.

PubMed

Nicolson, Garth L

2014-06-01

In 1972 the Fluid-Mosaic Membrane Model of membrane structure was proposed based on thermodynamic principals of organization of membrane lipids and proteins and available evidence of asymmetry and lateral mobility within the membrane matrix [S. J. Singer and G. L. Nicolson, Science 175 (1972) 720-731]. After over 40years, this basic model of the cell membrane remains relevant for describing the basic nano-structures of a variety of intracellular and cellular membranes of plant and animal cells and lower forms of life. In the intervening years, however, new information has documented the importance and roles of specialized membrane domains, such as lipid rafts and protein/glycoprotein complexes, in describing the macrostructure, dynamics and functions of cellular membranes as well as the roles of membrane-associated cytoskeletal fences and extracellular matrix structures in limiting the lateral diffusion and range of motion of membrane components. These newer data build on the foundation of the original model and add new layers of complexity and hierarchy, but the concepts described in the original model are still applicable today. In updated versions of the model more emphasis has been placed on the mosaic nature of the macrostructure of cellular membranes where many protein and lipid components are limited in their rotational and lateral motilities in the membrane plane, especially in their natural states where lipid-lipid, protein-protein and lipid-protein interactions as well as cell-matrix, cell-cell and intracellular membrane-associated protein and cytoskeletal interactions are important in restraining the lateral motility and range of motion of particular membrane components. The formation of specialized membrane domains and the presence of tightly packed integral membrane protein complexes due to membrane-associated fences, fenceposts and other structures are considered very important in describing membrane dynamics and architecture. These structures along with membrane-associated cytoskeletal and extracellular structures maintain the long-range, non-random mosaic macro-organization of membranes, while smaller membrane nano- and submicro-sized domains, such as lipid rafts and protein complexes, are important in maintaining specialized membrane structures that are in cooperative dynamic flux in a crowded membrane plane. This Article is Part of a Special Issue Entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy. © 2013.

Natural Products from the Lithistida: A Review of the Literature since 2000

PubMed Central

Winder, Priscilla L.; Pomponi, Shirley A.; Wright, Amy E.

2011-01-01

Lithistid sponges are known to produce a diverse array of compounds ranging from polyketides, cyclic and linear peptides, alkaloids, pigments, lipids, and sterols. A majority of these structurally complex compounds have very potent and interesting biological activities. It has been a decade since a thorough review has been published that summarizes the literature on the natural products reported from this amazing sponge order. This review provides an update on the current taxonomic classification of the Lithistida, describes structures and biological activities of 131 new natural products, and discusses highlights from the total syntheses of 16 compounds from marine sponges of the Order Lithistida providing a compilation of the literature since the last review published in 2002. PMID:22363244

Structural Changes and Proapoptotic Peroxidase Activity of Cardiolipin-Bound Mitochondrial Cytochrome c

PubMed Central

Mandal, Abhishek; Hoop, Cody L.; DeLucia, Maria; Kodali, Ravindra; Kagan, Valerian E.; Ahn, Jinwoo; van der Wel, Patrick C.A.

2015-01-01

The cellular process of intrinsic apoptosis relies on the peroxidation of mitochondrial lipids as a critical molecular signal. Lipid peroxidation is connected to increases in mitochondrial reactive oxygen species, but there is also a required role for mitochondrial cytochrome c (cyt-c). In apoptotic mitochondria, cyt-c gains a new function as a lipid peroxidase that catalyzes the reactive oxygen species-mediated chemical modification of the mitochondrial lipid cardiolipin (CL). This peroxidase activity is caused by a conformational change in the protein, resulting from interactions between cyt-c and CL. The nature of the conformational change and how it causes this gain-of-function remain uncertain. Via a combination of functional, structural, and biophysical experiments we investigate the structure and peroxidase activity of cyt-c in its membrane-bound state. We reconstituted cyt-c with CL-containing lipid vesicles, and determined the increase in peroxidase activity resulting from membrane binding. We combined these assays of CL-induced proapoptotic activity with structural and dynamic studies of the membrane-bound protein via solid-state NMR and optical spectroscopy. Multidimensional magic angle spinning (MAS) solid-state NMR of uniformly 13C,15N-labeled protein was used to detect site-specific conformational changes in oxidized and reduced horse heart cyt-c bound to CL-containing lipid bilayers. MAS NMR and Fourier transform infrared measurements show that the peripherally membrane-bound cyt-c experiences significant dynamics, but also retains most or all of its secondary structure. Moreover, in two-dimensional and three-dimensional MAS NMR spectra the CL-bound cyt-c displays a spectral resolution, and thus structural homogeneity, that is inconsistent with extensive membrane-induced unfolding. Cyt-c is found to interact primarily with the membrane interface, without significantly disrupting the lipid bilayer. Thus, membrane binding results in cyt-c gaining the increased peroxidase activity that represents its pivotal proapoptotic function, but we do not observe evidence for large-scale unfolding or penetration into the membrane core. PMID:26536264

Keratin film ablation for the fabrication of brick and mortar skin structure using femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Haq, Bibi Safia; Khan, Hidayat Ullah; Dou, Yuehua; Alam, Khan; Attaullah, Shehnaz; Zari, Islam

2015-09-01

The patterning of thin keratin films has been explored to manufacture model skin surfaces based on the "bricks and mortar" view of the relationship between keratin and lipids. It has been demonstrated that laser light is capable of preparing keratin-based "bricks and mortar" wall structure as in epidermis, the outermost layer of the human skin. "Bricks and mortar" pattern in keratin films has been fabricated using an ArF excimer laser (193 nm wavelength) and femtosecond laser (800 and 400 nm wavelength). Due to the very low ablation threshold of keratin, femtosecond laser systems are practical for laser processing of proteins. These model skin structures are fabricated for the first time that will help to produce potentially effective moisturizing products for the protection of skin from dryness, diseases and wrinkles.

Versatile platform for nanotechnology based on circular permutations of chaperonin protein

NASA Technical Reports Server (NTRS)

McMillan, R. Andrew (Inventor); Kagawa, Hiromi (Inventor); Paavola, Chad D. (Inventor); Chan, Suzanne L. (Inventor); Li, Yi-Fen (Inventor); Trent, Jonathan D. (Inventor)

2010-01-01

The present invention provides chaperonin polypeptides which are modified to include N-terminal and C-terminal ends that are relocated from the central pore region to various different positions in the polypeptide which are located on the exterior of the folded modified chaperonin polypeptide. In the modified chaperonin polypeptide, the naturally-occurring N-terminal and C-terminal ends are joined together directly or with an intervening linker peptide sequence. The relocated N-terminal or C-terminal ends can be covalently joined to, or bound with another molecule such as a nucleic acid molecule, a lipid, a carbohydrate, a second polypeptide, or a nanoparticle. The modified chaperonin polypeptides can assemble into double-ringed chaperonin structures. Further, the chaperonin structures can organize into higher order structures such as nanofilaments or nanoarrays which can be used to produce nanodevices and nanocoatings.

Design and Synthesis of Archaea-Inspired Tetraether Lipids

NASA Astrophysics Data System (ADS)

Koyanagi, Takaoki

Maintaining the correct ion homeostasis across membranes is a major challenge in both nature and artificial systems. Archaea, have evolved to solve membrane permeability problems to survive in extreme environments by incorporating unique structural features found in their lipid. Specifically, inclusion of phytanyl side chains, ether glycerol linkages, tethering of lipids, cycloalkanes, and different polar lipid headgroups into their lipid membrane are believed to contribute to membrane stability. We sought to gain a better understanding of the functional benefits attributed to these structural features to membrane stability to design a new class of synthetic Archaea inspired lipid membranes that can be used to overcome limitations (i.e. unstable in serum environment, high background leakage, and prone to hydrolysis) found in current lipid based technologies. Leakage experiments revealed liposomes made from GMGTPC (glycerol monoalkyl glycerol tetraether lipid with phosphatidylcholine headgroup) demonstrated a two order magnitude reduction in membrane leakage to small ions when compared with liposomes made from EggPC. Additionally, liposomes composed of GMGTPC-CH (cyclohexane integrated) lipid displayed an additional 40% decrease in membrane leakage to small ions when compared with liposomes made from GMGTPC lipids. Furthermore, leakage experiments revealed a higher degree of tolerance to headgroup modifications to membrane leakage for liposomes made from GMGT lipid analogs when compared with liposomes made from POPC. After designing an optimal tetraether lipid scaffold that incorporates key Archaeal structural features for membrane leakage, we explored to integrate strategies employed by eukaryotes to improve membrane properties (i.e. addition of cholesterol). Liposomes made from the hybrid lipid, GcGTPC-CH, displayed a five-fold decrease in membrane leakage when compared with liposomes made from GMGTPC-CH, while maintaining functional membrane properties similar to membranes made from diacyl lipids. Lastly, we engineered a thiol responsive hybrid lipid, GcGT(S-S)PC-CH, that demonstrated similar membrane stability in serum as GcGTPC-CH. Gratifyingly, doxorubicin loaded liposomes composed of GcGT(S-S)PC-CH liposomes displayed a 4 or 20-fold increase in toxicity to HeLa cells when compared with liposomes made from GcGTPC-CH or Doxil, respectively. This work represents a first step towards development of stimuli-responsive tetraether lipids that may offer advantages in membrane properties to be used in cancer therapy.

The structure of ions and zwitterionic lipids regulates the charge of dipolar membranes.

PubMed

Szekely, Or; Steiner, Ariel; Szekely, Pablo; Amit, Einav; Asor, Roi; Tamburu, Carmen; Raviv, Uri

2011-06-21

In pure water, zwitterionic lipids form lamellar phases with an equilibrium water gap on the order of 2 to 3 nm as a result of the dominating van der Waals attraction between dipolar bilayers. Monovalent ions can swell those neutral lamellae by a small amount. Divalent ions can adsorb onto dipolar membranes and charge them. Using solution X-ray scattering, we studied how the structure of ions and zwitterionic lipids regulates the charge of dipolar membranes. We found that unlike monovalent ions that weakly interact with all of the examined dipolar membranes, divalent and trivalent ions adsorb onto membranes containing lipids with saturated tails, with an association constant on the order of ∼10 M(-1). One double bond in the lipid tail is sufficient to prevent divalent ion adsorption. We suggest that this behavior is due to the relatively loose packing of lipids with unsaturated tails that increases the area per lipid headgroup, enabling their free rotation. Divalent ion adsorption links two lipids and limits their free rotation. The ion-dipole interaction gained by the adsorption of the ions onto unsaturated membranes is insufficient to compensate for the loss of headgroup free-rotational entropy. The ion-dipole interaction is stronger for cations with a higher valence. Nevertheless, polyamines behave as monovalent ions near dipolar interfaces in the sense that they interact weakly with the membrane surface, whereas in the bulk their behavior is similar to that of multivalent cations. Advanced data analysis and comparison with theory provide insight into the structure and interactions between ion-induced regulated charged interfaces. This study models biologically relevant interactions between cell membranes and various ions and the manner in which the lipid structure governs those interactions. The ability to monitor these interactions creates a tool for probing systems that are more complex and forms the basis for controlling the interactions between dipolar membranes and charged proteins or biopolymers for encapsulation and delivery applications. © 2011 American Chemical Society

Subretinal Pigment Epithelial Deposition of Drusen Components Including Hydroxyapatite in a Primary Cell Culture Model

DOE PAGES

Pilgrim, Matthew G.; Lengyel, Imre; Lanzirotti, Antonio; ...

2017-02-01

Extracellular deposits containing hydroxyapatite, lipids, proteins, and trace metals that form between the basal lamina of the RPE and the inner collagenous layer of Bruch’s membrane are hallmarks of early AMD. We examined whether cultured RPE cells could produce extracellular deposits containing all of these molecular components. Retinal pigment epithelium cells isolated from freshly enucleated porcine eyes were cultured on Transwell membranes for up to 6 months. Deposit composition and structure were characterized using light, fluorescence, and electron microscopy; synchrotron x-ray diffraction and x-ray fluorescence; secondary ion mass spectroscopy; and immunohistochemistry. Apparently functional primary RPE cells, when cultured on 10-lm-thickmore » inserts with 0.4-lm-diameter pores, can produce sub-RPE deposits that contain hydroxyapatite, lipids, proteins, and trace elements, without outer segment supplementation, by 12 weeks. In conclusion, the data suggest that sub-RPE deposit formation is initiated, and probably regulated, by the RPE, as well as the loss of permeability of the Bruch’s membrane and choriocapillaris complex associated with age and early AMD. This cell culture model of early AMD lesions provides a novel system for testing new therapeutic interventions against sub-RPE deposit formation, an event occurring well in advance of the onset of vision loss.« less