These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

The Sleep-inducing Lipid Oleamide Deconvolutes Gap Junction Communication and Calcium Wave Transmission in Glial Cells  

Microsoft Academic Search

Oleamide is a sleep-inducing lipid originally isolated from the cerebrospinal fluid of sleep-deprived cats. Oleamide was found to potently and selectively in- activate gap junction-mediated communication be- tween rat glial cells. In contrast, oleamide had no effect on mechanically stimulated calcium wave transmission in this same cell type. Other chemical compounds tradi- tionally used as inhibitors of gap junctional communi-

Xiaojun Guan; Benjamin F. Cravatt; George R. Ehring; James E. Hall; Dale L. Boger; Richard A. Lerner; Norton B. Gilula

1997-01-01

2

The Sleep-inducing Lipid Oleamide Deconvolutes Gap Junction Communication and Calcium Wave Transmission in Glial Cells  

PubMed Central

Oleamide is a sleep-inducing lipid originally isolated from the cerebrospinal fluid of sleep-deprived cats. Oleamide was found to potently and selectively inactivate gap junction–mediated communication between rat glial cells. In contrast, oleamide had no effect on mechanically stimulated calcium wave transmission in this same cell type. Other chemical compounds traditionally used as inhibitors of gap junctional communication, like heptanol and 18?-glycyrrhetinic acid, blocked not only gap junctional communication but also intercellular calcium signaling. Given the central role for intercellular small molecule and electrical signaling in central nervous system function, oleamide- induced inactivation of glial cell gap junction channels may serve to regulate communication between brain cells, and in doing so, may influence higher order neuronal events like sleep induction. PMID:9412472

Guan, Xiaojun; Cravatt, Benjamin F.; Ehring, George R.; Hall, James E.; Boger, Dale L.; Lerner, Richard A.; Gilula, Norton B.

1997-01-01

3

In Vivo Evidence that N-Oleoylglycine Acts Independently of Its Conversion to Oleamide  

PubMed Central

Oleamide (cis-9-octadecenamide) is a member of an emerging class of lipid-signaling molecules, the primary fatty acid amides. A growing body of evidence indicates that oleamide mediates fundamental neurochemical processes including sleep, thermoregulation, and nociception. Nevertheless, the mechanism for oleamide biosynthesis remains unknown. The leading hypothesis holds that oleamide is synthesized from oleoylglycine via the actions of the peptide amidating enzyme, peptidylglycine alpha amidating monooxygenase (PAM). The present study investigated this hypothesis using pharmacologic treatments, physiologic assessments, and measurements of serum oleamide levels using a newly development enzyme-linked immunosorbant assay (ELISA). Oleamide and oleoylglycine both induced profound hypothermia and decreased locomotion, over equivalent dose ranges and time courses, whereas, closely related compounds, stearamide and oleic acid, were essentially without effect. While the biologic actions of oleamide and oleoylglycine were equivalent, the two compounds differed dramatically with respect to their effects on serum levels of oleamide. Oleamide administration (80 mg/kg) elevated blood-borne oleamide by eight-fold, whereas, the same dose of oleoylglycine had no effect on circulating oleamide levels. In addition, pretreatment with the established PAM inhibitor, disulfiram, produced modest reductions in the hypothermic responses to both oleoylglycine and oleamide, suggesting that the effects of disulfiram were not mediated through inhibition of PAM and a resulting decrease in the formation of oleamide from oleoylglycine. Collectively, these findings raise the possibilities that: (1) oleoylglycine possesses biologic activity that is independent of its conversion to oleamide, and (2) the increased availability of oleoylglycine as a potential substrate does not drive the biosynthesis of oleamide. PMID:17085322

Chaturvedi, Shalini; Driscoll, William J.; Elliot, Brenda M.; Faraday, Martha M.; Grunberg, Neil E.; Mueller, Gregory P.

2006-01-01

4

Oleamide restores sleep in adult rats that were subjected to maternal separation.  

PubMed

Maternal separation (MS) induces a series of changes in rats' behavior; among them a reduction in spontaneous sleep. One potentially impaired system is the endocannabinoid system (eCBs), since it contributes to generate sleep. To investigate if there are situations early in life that affect the eCBs, which would contribute to make rats vulnerable to suffering insomnia, we studied the rodent model of MS. Rats were separated from their mothers for 3h-periods daily, from postnatal day (PND) 2 to PND 16. Once they gained 250g of body weight (adult rats), they were implanted with electrodes to record the sleep-waking cycle (SWC). MS rats and non-MS (NMS) siblings were assigned to one of the following groups: vehicle, oleamide (OLE, an agonist of the cannabinoid receptor 1, CB1R), OLE+AM251 (an antagonist of the CB1R) and AM251 alone. Expression of the CBR1 receptor was also analyzed in the frontal cortex (FCx) and in the hippocampus (HIP) of both NMS and MS rats. Results indicated that MS induced a reduction in both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep with the consequent increase in waking (W) as compared to NMS siblings. OLE normalized the SWC, and AM251 blocked such an effect. CB1R expression was reduced in the FCx and in the HIP of MS rats. Our results indicate that MS reduces sleep and CB1R expression and OLE improves sleep in adult rats. PMID:22975223

Reyes Prieto, Nidia M; Romano López, Antonio; Pérez Morales, Marcel; Pech, Olivia; Méndez-Díaz, Mónica; Ruiz Contreras, Alejandra E; Prospéro-García, Oscar

2012-12-01

5

Circadian rhythms in effects of hypnotics and sleep inducers.  

PubMed

Chronopharmacology involves the investigation of drug effects as a function of biological time and the investigation of drug effects on rhythm characteristics. Three new concepts must be considered: (a) the chronokinetics of a drug, embracing rhythmic (circadian) changes in drug bioavailability (or pharmacokinetics) and its excretion (urinary among others); (b) the chronaesthesia of a biosystem to a drug, i.e. circadian changes in the susceptibility of any biosystem to a drug (including organ systems, parasites, etc.); skin and bronchial chronaesthesia to various agents have been documented in man; and (c) the chronergy of a drug, taking into consideration its chronokinetics and the chronaesthesia of the involved organismic biosystems. The term chronergy includes rhythmic changes in the overall effects and in the effectiveness of some drugs. Clinical chronopharmacology is useful for solving problems of drug optimization, i.e. enhancing the desired efficiency of a drug and reducing its undesired effects. Circadian rhythms can be demonstrated in various effects of drugs on sleep, anaesthesia and related processes. For example, in the rat the duration of sleep induced by substances such as pentobarbital, hexobarbital, Althesin (alphaxadone and alphadoline in castor oil) is circadian system stage-dependent. Time-dependent changes of liver enzymes (e.g. hexobarbital oxidase) play a role in these circadian rhythms. The clinical chronopharmacokinetics of benzodiazepines have been documented in man. Chronopharmacologic methods can be used to study desired and undesired hypnotic effects of substances. Such is the case of new antihistamines (anti-H1), which do not induce sleepiness, in either acute or chronic administration. Pertinent also is the problem of intolerance to shift-work. Intolerant shift-workers are subject to internal desynchronization between at least two rhythms (e.g. activity-rest cycle and body temperature). Clinically these workers suffer from sleep disturbances, persistent fatigue and are regular users of sleeping pills, which is also a symptom of intolerance. However, over the long-term, these drugs are of no help to intolerant shift-workers. PMID:3514493

Reinberg, A

1986-01-01

6

Delta sleep-inducing peptide and its tetrapeptide analogue alleviate severity of metaphit seizures  

Microsoft Academic Search

The effects of delta sleep-inducing peptide (DSIP) and its tetrapeptide analogue, DSIP(1-4), on metaphit-induced audiogenic seizures were studied. Five groups of adult male Wistar rats were intraperitoneally treated with (1) saline, (2) metaphit, (3) DSIP, (4) metaphit+DSIP and (5) metaphit+DSIP(1-4). To examine blocking effects of DSIP and its analogue on fully developed metaphit seizures, the last two groups were injected

Olivera Stanojlovi?; Dragana Živanovi?; Slobodan Mirkovi?; Inessa Mikhaleva

2004-01-01

7

Lipids  

NSDL National Science Digital Library

Paul Anderson describes the lipids (of the fats). He explains how they are an important source of energy but are also required to cell membranes. He explains how the hydrocarbon tails in triglycerides contain energy available for life. He also explains how phospholipids construct, and cholesterol molecules main the cell membrane.

Anderson, Paul

2013-03-12

8

Lipids  

NSDL National Science Digital Library

Quiz questions from the organic chemistry question bank provide students with an excellent opportunity to review key concepts. This group of questions focuses on fat soluble molecules called lipids. Questions on fatty acids, triacylglycerols, terpenes, and steroids are all provided here for review.

Reich, Ieva

9

Interaction of Delta Sleep-inducing Peptide and Valproate on Metaphit Audiogenic Seizure Model in Rats  

Microsoft Academic Search

Effects of valproate (VPA), a conventional antiepileptic drug and natural delta sleep-inducing peptide (DSIP) on metaphit\\u000a (1-[1-(3-isothiocyanatophenyl)-cyclohexyl]-piperidine)-induced audiogenic reflex epilepsy were studied. For the purpose of the study, valproate in the doses of 50 or 75 mg\\/kg and\\u000a DSIP (1.0 mg\\/kg) was i.p. injected either alone or in combination to adult Wistar male rats with fully developed metaphit\\u000a seizures after eight audiogenic

Olivera Stanojlovi?; Dragan Hrn?i?; Aleksandra Raši?; Helena Lon?ar-Stevanovi?; Dragan Djuric; Veselinka Šuši?

2007-01-01

10

Delta-sleep inducing peptide entrapment in the charged macroporous matrices.  

PubMed

Various biomolecules, for example proteins, peptides etc., entrapped in polymer matrices, impact interactions between matrix and cells, including stimulation of cell adhesion and proliferation. Delta-sleep inducing peptide (DSIP) possesses numerous beneficial properties, including its abilities in burn treatment and neuronal protection. DSIP entrapment in two macroporous polymer matrices based on copolymer of dimethylaminoethyl methacrylate and methylen-bis-acrylamide (Co-DMAEMA-MBAA) and copolymer of acrylic acid and methylen-bis-acrylamide (Co-AA-MBAA) has been studied. Quite 100% of DSIP has been entrapped into positively charged Co-DMAEMA-MBAA matrix, while the quantity of DSIP adsorbed on negatively charged Co-AA-MBAA was only 2-6%. DSIP release from Co-DMAEMA-MBAA was observed in saline solutions (0.9% NaCl and PBS) while there was no DSIP release in water or 25% ethanol, thus ionic strength was a reason of this process. PMID:25063142

Sukhanova, Tatiana V; Artyukhov, Alexander A; Gurevich, Yakov M; Semenikhina, Marina A; Prudchenko, Igor A; Shtilman, Mikhail I; Markvicheva, Elena A

2014-09-01

11

Membrane protein crystallization in meso: lipid type-tailoring of the cubic phase.  

PubMed Central

Hydrated monoolein forms the cubic-Pn3m mesophase that has been used for in meso crystallization of membrane proteins. The crystals have subsequently provided high-resolution structures by crystallographic means. It is possible that the hosting cubic phase created by monoolein alone, which itself is not a common membrane component, will limit the range of membrane proteins crystallizable by the in meso method. With a view to expanding the range of applicability of the method, we investigated by x-ray diffraction the degree to which the reference cubic-Pn3m phase formed by hydrated monoolein could be modified by other lipid types. These included phosphatidylcholine (PC), phosphatidylethanolamine, phosphatidylserine, cardiolipin, lyso-PC, a polyethylene glycol-lipid, 2-monoolein, oleamide, and cholesterol. The results show that all nine lipids were accommodated in the cubic phase to some extent without altering phase identity. The positional isomer, 2-monoolein, was tolerated to the highest level. The least well tolerated were the anionic lipids, followed by lyso-PC. The others were accommodated to the extent of 20-25 mol %. Beyond a certain concentration limit, the lipid additives either triggered one or a series of phase transitions or saturated the phase and separated out as crystals, as seen with oleamide and cholesterol. The series of phases observed and their order of appearance were consistent with expectations in terms of interfacial curvature changes. The changes in phase type and microstructure have been rationalized on the basis of lipid molecular shape, interfacial curvature, and chain packing energy. The data should prove useful in the rational design of cubic phase crystallization matrices with different lipid profiles that match the needs of a greater range of membrane proteins. PMID:12496106

Cherezov, Vadim; Clogston, Jeffrey; Misquitta, Yohann; Abdel-Gawad, Wissam; Caffrey, Martin

2002-01-01

12

Metabolomic study of lipids in serum for biomarker discovery in Alzheimer's disease using direct infusion mass spectrometry.  

PubMed

In this study, we demonstrated the potential of direct infusion mass spectrometry for the lipidomic characterization of Alzheimer's disease. Serum samples were extracted for lipids recovery, and directly analyzed using an electrospray source. Metabolomic fingerprints were subjected to multivariate analysis in order to discriminate between groups of patients and healthy controls, and then some key-compounds were identified as possible markers of Alzheimer's disease. Major differences were found in lipids, although some low molecular weight metabolites also showed significant changes. Thus, important metabolic pathways involved in neurodegeneration could be studied on the basis of these perturbations, such as membrane breakdown (phospholipids and diacylglycerols), oxidative stress (prostaglandins, imidazole and histidine), alterations in neurotransmission systems (oleamide and putrescine) and hyperammonaemia (guanidine and arginine). Moreover, it is noteworthy that some of these potential biomarkers have not been previously described for Alzheimer's disease. PMID:24992214

González-Domínguez, R; García-Barrera, T; Gómez-Ariza, J L

2014-09-01

13

[Delta-sleep inducing peptide entrapment and release from polymer hydrogels based on modified polyvinyl alcohol in vitro].  

PubMed

The aim of the study was to entrap delta-sleep inducing peptide (DSIP) in cross-linked poly(vinyl alcohol)-based hydrogels of different structures and to evaluate peptide release kinetics from these hydrogels using an in vitro model. Isotropic and macroporous hydrogels on the basis of poly(vinyl alcohol) acrylic derivative (Acr-PVA) as well as macroporous hydogels containing epoxy groups which were synthesized by copolymerization of this monomer with glycidyl methacrylate. The isotropic hydrogels were fabricated at positive temperatures while the macroporous hydrogels (cryogels) were prepared at the temperatures below zero. The peptide was entrapped into macroporous modified PVA hydrogels by addition of a peptide solution on previously fabricated matrices, while into PVA-GMA hydrogels containing epoxy groups peptide immobilization was carried out by incubation of hydrogel matrices in the peptide solution. In the case of isotropic hydrogels the peptide was added into the polymer mixture at a hydrogel formation reaction. The peptide release kinetics was studied by incubation of hydrogels in PBS (pH 7.4), in physiological solution (0.9% NaCl) and in water. DSIP concentration in supernatants was determined by phase-reverse HPLC. DSIP release from the macroporous PVA hydrogel after 30 min incubation was 74, 70 and 64% in water, PBS and 0.9% NaCl, relatively, and it was completed in 3 hs. From the isotropic hydrogel the release neither peptide nor products of its degradation was not observed even after 48 hs of incubation. For freshly prepared hydrogel the release kinetics was as follows: 27 and 78% in 30 and 33 hs, relatively. In the case of the lyophilized hydrogel samples the peptide release was 63% in 30 min incubation while drying patterns at room temperature for 3 days resulted in significant peptide loss because its structure damage. PMID:23650723

Sukhanova, T V; Artiukhov, A A; Prudchenko, I A; Golunova, A S; Seminikhina, M A; Shtil'man, M I; Markvicheva, E A

2013-01-01

14

Implication of tryptophan in the stimulatory effect of delta-sleep-inducing peptide on indole secretion from perifused rat pineal glands.  

PubMed

We have recently demonstrated that delta-sleep-inducing peptide (DSIP) stimulates indolamine secretion from rat pineal glands. In the present study, we show that tryptophan (TRP), as well as DSIP, stimulate melatonin (MEL) and 5-methoxy-tryptophol (5-ML) secretion in a dose-dependent manner between 5 x 10(-6) and 10(-4) M. The kinetic characteristics of the MEL and 5-ML secretion and the response induced by the two substances were similar. The increase in MEL secretion in response to 10(-4) M DSIP was completely inhibited by pretreatment of the pineals with 10(-5) M phenanthroline (amino-peptidase inhibitor), suggesting that stimulatory effect of DSIP was due to TRP liberated by peptide degradation. This mechanism occurring in the pineal was confirmed using 10(-4) M para-chlorophenylalamine (TRP hydroxylase inhibitor), which reduced the pineal response to 10(-4) and 10(-5) M DSIP by 50 and 100%, respectively. PMID:1307916

Ouichou, A; Pévet, P

1992-01-01

15

Oat lipids  

Microsoft Academic Search

Oats are a significant world crop. While nutritional interest in food oats has concentrated on oats as a source of dietary\\u000a fiber, the lipid component has both nutritional and technological potential. Thus, the lipid fraction of the oat grain determines\\u000a in large measure its energy content and has a significant impact on nutritional quality. The oat lipids mediate the pasting

Meixue Zhou; Kevin Robards; Malcolm Glennie-Holmes; Stuart Helliwell

1999-01-01

16

Lipid Profile  

MedlinePLUS

... Necessity of Fasting Before Cholesterol and Other Lipid Tests (2013), More Youths Need Cholesterol Screening, says AAP (2011) Elsewhere On The Web Familydoctor.org: Heart Disease, Assessing Your Risk American ...

17

Lipid Wordsearch  

NASA Astrophysics Data System (ADS)

This puzzle embeds 37 names, terms, prefixes and acronyms about lipid chemistry in a 17 x 13-letter matrix. A descriptive narrative with underlined spaces to be filled gives clues to the terms a student needs to find. When all are found, the 16 unused letters complete a sentence that describes a major function of these biochemicals. It is suitable for any undergraduate or graduate course where lipid chemistry and basic metabolism are studied.

Helser, Terry L.

2000-04-01

18

Lipid Nanotechnology  

PubMed Central

Nanotechnology is a multidisciplinary field that covers a vast and diverse array of devices and machines derived from engineering, physics, materials science, chemistry and biology. These devices have found applications in biomedical sciences, such as targeted drug delivery, bio-imaging, sensing and diagnosis of pathologies at early stages. In these applications, nano-devices typically interface with the plasma membrane of cells. On the other hand, naturally occurring nanostructures in biology have been a source of inspiration for new nanotechnological designs and hybrid nanostructures made of biological and non-biological, organic and inorganic building blocks. Lipids, with their amphiphilicity, diversity of head and tail chemistry, and antifouling properties that block nonspecific binding to lipid-coated surfaces, provide a powerful toolbox for nanotechnology. This review discusses the progress in the emerging field of lipid nanotechnology. PMID:23429269

Mashaghi, Samaneh; Jadidi, Tayebeh; Koenderink, Gijsje; Mashaghi, Alireza

2013-01-01

19

Lipid Storage Diseases  

MedlinePLUS

NINDS Lipid Storage Diseases Information Page Condensed from Lipid Storage Diseases Fact Sheet Table of Contents (click to jump ... Trials Organizations Additional resources from MedlinePlus What are Lipid Storage Diseases? Lipid storage diseases are a group ...

20

Lipids/Phospholipids Lipid oxidation  

E-print Network

.schiller@medizin.uni-leipzig.de http://www.uni-leipzig.de/~schij/ Teuber, K.; riemer, T.; Schiller, J. Thin-Layer Chromatography coupling between ma- trix-assisted laser desorption/ioni- zation MS and high-performance thin-layer chromatography (HPTLC) that helps to identify even minor species in complex lipid mixtures. HPTLC/MALDI is very

Schüler, Axel

21

Lipid14: The Amber Lipid Force Field  

PubMed Central

The AMBER lipid force field has been updated to create Lipid14, allowing tensionless simulation of a number of lipid types with the AMBER MD package. The modular nature of this force field allows numerous combinations of head and tail groups to create different lipid types, enabling the easy insertion of new lipid species. The Lennard-Jones and torsion parameters of both the head and tail groups have been revised and updated partial charges calculated. The force field has been validated by simulating bilayers of six different lipid types for a total of 0.5 ?s each without applying a surface tension; with favorable comparison to experiment for properties such as area per lipid, volume per lipid, bilayer thickness, NMR order parameters, scattering data, and lipid lateral diffusion. As the derivation of this force field is consistent with the AMBER development philosophy, Lipid14 is compatible with the AMBER protein, nucleic acid, carbohydrate, and small molecule force fields. PMID:24803855

2015-01-01

22

-Metabolism Part Ill: Lipids  

E-print Network

- Metabolism Part Ill: Lipids George M. Bodner Purdue University, West Lafayette,IN 47907 Three. Lipids therefore exhibit a wide variety of structures charac- terized by the presence of hydrophobic groups. Lipids are often divided into two classes. Complex lipids such as "fats" and "oils" contain fatty

Bodner, George M.

23

Lipid antigens in immunity  

PubMed Central

Lipids are not only a central part of human metabolism but also play diverse and critical roles in the immune system. As such, they can act as ligands of lipid-activated nuclear receptors, control inflammatory signaling through bioactive lipids such as prostaglandins, leukotrienes, lipoxins, resolvins, and protectins, and modulate immunity as intracellular phospholipid- or sphingolipid-derived signaling mediators. In addition, lipids can serve as antigens and regulate immunity through the activation of lipid-reactive T cells, which is the topic of this review. We will provide an overview of the mechanisms of lipid antigen presentation, the biology of lipid-reactive T cells, and their contribution to immunity. PMID:23999493

Dowds, C. Marie; Kornell, Sabin-Christin

2014-01-01

24

Lipid antigens in immunity.  

PubMed

Lipids are not only a central part of human metabolism but also play diverse and critical roles in the immune system. As such, they can act as ligands of lipid-activated nuclear receptors, control inflammatory signaling through bioactive lipids such as prostaglandins, leukotrienes, lipoxins, resolvins, and protectins, and modulate immunity as intracellular phospholipid- or sphingolipid-derived signaling mediators. In addition, lipids can serve as antigens and regulate immunity through the activation of lipid-reactive T cells, which is the topic of this review. We will provide an overview of the mechanisms of lipid antigen presentation, the biology of lipid-reactive T cells, and their contribution to immunity. PMID:23999493

Dowds, C Marie; Kornell, Sabin-Christin; Blumberg, Richard S; Zeissig, Sebastian

2014-01-01

25

Daunorubicin Lipid Complex Injection  

MedlinePLUS

Daunorubicin lipid complex is used to treat advanced Kaposi's sarcoma (a type of cancer that causes abnormal tissue to ... body) related to acquired immunodeficiency syndrome (AIDS). Daunorubicin lipid complex is in a class of medications called ...

26

Vincristine Lipid Complex Injection  

MedlinePLUS

Vincristine lipid complex is used to treat a certain type of acute lymphoblastic leukemia (ALL; a type of cancer ... least two different treatments with other medications. Vincristine lipid complex is in a class of medications called ...

27

Doxorubicin Lipid Complex Injection  

MedlinePLUS

Doxorubicin lipid complex is used to treat ovarian cancer that has not improved or that has worsened after treatment with other medications. Doxorubicin lipid complex is also used to treat Kaposi's sarcoma ( ...

28

Biomolecular archaeology and lipids  

Microsoft Academic Search

Medium?sized biomolecules, particularly lipids, can frequently be detected in ancient materials. The structures and compositions of mixtures of lipids can provide direct evidence for their origin, and hence, evidence for human activity in the past. An important concept in the field of biomolecular archaeology of lipids is that of ‘biomarkers’. Archaeological biomarkers are characteristic compounds (or mixtures of compounds) found

R. P. Evershed

1993-01-01

29

Lipids in the Limelight  

NSDL National Science Digital Library

The term lipid can bring to mind many associations. Unfortunately, these are often negative, such as the contribution that excessive dietary fat makes to heart disease. But lipids are also essential components of cell membranes, and during the past several years, cell biologists have found that lipid molecules play many more dynamic roles as well, helping to control a majority of cellular activities. Consequently, lipids are major determinants of many pathologies in addition to heart disease. This article introduces a special issue of Science highlighting a few of the recent emerging themes in lipid biology.

Lisa Chong (AAAS;); Jean Marx (AAAS;)

2001-11-30

30

Phospholipids and lipid droplets.  

PubMed

Lipid droplets are ubiquitous cellular organelles that allow cells to store large amounts of neutral lipids for membrane synthesis and energy supply in times of starvation. Compared to other cellular organelles, lipid droplets are structurally unique as they are made of a hydrophobic core of neutral lipids and are separated to the cytosol only by a surrounding phospholipid monolayer. This phospholipid monolayer consists of over a hundred different phospholipid molecular species of which phosphatidylcholine is the most abundant lipid class. However, lipid droplets lack some indispensable activities of the phosphatidylcholine biogenic pathways suggesting that they partially depend on other organelles for phosphatidylcholine synthesis. Here, we discuss very recent data on the composition, origin, transport and function of the phospholipid monolayer with a particular emphasis on the phosphatidylcholine metabolism on and for lipid droplets. In addition, we highlight two very important quantitative aspects: (i) The amount of phospholipid required for lipid droplet monolayer expansion is remarkably small and (ii) to maintain the invariably round shape of lipid droplets, a cell must have a highly sensitive but so far unknown mechanism that regulates the ratio of phospholipid to neutral lipid in lipid droplets. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:23246574

Penno, Anke; Hackenbroich, Gregor; Thiele, Christoph

2013-03-01

31

Microalgae lipid characterization.  

PubMed

To meet the growing interest of utilizing microalgae biomass in the production of biofuels and nutraceutical and pharmaceutical lipids, we need suitable analytical methods and a comprehensive database for their lipid components. The objective of the present work was to demonstrate methodology and provide data on fatty acid composition, lipid class content and composition, characteristics of the unsaponifiables, and type of chlorophylls of five microalgae. Microalgae lipids were fractionated into TAG, FFA, and polar lipids using TLC, and the composition of fatty acids in total lipids and in each lipid class, hydrocarbons, and sterols were determined by GC-MS. Glyco- and phospholipids were profiled by LC/ESI-MS. Chlorophylls and their related metabolites were qualified by LC/APCI-MS. The melting and crystallization profiles of microalgae total lipids and their esters were analyzed by DSC to evaluate their potential biofuel applications. Significant differences and complexities of lipid composition among the algae tested were observed. The compositional information is valuable for strain selection, downstream biomass fractionation, and utilization. PMID:25608629

Yao, Linxing; Gerde, Jose A; Lee, Show-Ling; Wang, Tong; Harrata, Kamel A

2015-02-18

32

Sleep-Induced Changes in Associative Memory  

Microsoft Academic Search

The notion that dreaming might alter the strength of associative links in memory was first proposed almost 200 years ago. But no strong evidence of such altered associative links has been obtained. Semantic priming can be used to quantify the strength of associative links between pairs of words; it is thought to measure the automatic spread of activation from a

Robert Stickgold; Laurie Scott; Cynthia Rittenhouse; J. Allan Hobson

1999-01-01

33

Sleep-induced changes in associative memory.  

PubMed

The notion that dreaming might alter the strength of associative links in memory was first proposed almost 200 years ago. But no strong evidence of such altered associative links has been obtained. Semantic priming can be used to quantify the strength of associative links between pairs of words; it is thought to measure the automatic spread of activation from a "node" representing one word to nodes representing semantically related words. Semantic priming could thus be used to test for global alterations in the strengths of associative links across the wake-sleep cycle. Awakenings from REM and nonREM (NREM) sleep produce a period of state carry-over during which performance is altered as a result of the brain's slow transition to full wakefulness, and cognitive testing in this period can provide information about the functioning of the brain during the prior sleep period. When subjects were tested across the night--before and after a night's sleep as well as immediately following forced awakenings from REM and NREM sleep--weak priming (e. g., thief-wrong) was found to be state dependent (p = 0.016), whereas strong priming (e.g., hot-cold) was not (p = 0.89). Weak primes were most effective in the presleep and REM sleep conditions and least effective in NREM and postsleep conditions. Most striking are analyses comparing weak and strong priming within each wake-sleep state. Contrary to the normal pattern of priming, subjects awakened from REM sleep showed greater priming by weak primes than by strong primes (p = 0.01). This result was seen in each of three protocols. In contrast, strong priming exceeded weak priming in NREM sleep. The shift in weak priming seen after REM sleep awakenings suggests that cognition during REM sleep is qualitatively different from that of waking and NREM sleep and may reflect a shift in associative memory systems, a shift that we hypothesize underlies the bizarre and hyperassociative character of REM-sleep dreaming. Known changes in brainstem activity that control the transition into and maintenance of REM sleep provide a possible explanation of this shift. PMID:10198133

Stickgold, R; Scott, L; Rittenhouse, C; Hobson, J A

1999-03-01

34

Lipids and lipid metabolism in eukaryotic algae.  

PubMed

Eukaryotic algae are a very diverse group of organisms which inhabit a huge range of ecosystems from the Antarctic to deserts. They account for over half the primary productivity at the base of the food chain. In recent years studies on the lipid biochemistry of algae has shifted from experiments with a few model organisms to encompass a much larger number of, often unusual, algae. This has led to the discovery of new compounds, including major membrane components, as well as the elucidation of lipid signalling pathways. A major drive in recent research have been attempts to discover genes that code for expression of the various proteins involved in the production of very long-chain polyunsaturated fatty acids such as arachidonic, eicosapentaenoic and docosahexaenoic acids. Such work is described here together with information about how environmental factors, such as light, temperature or minerals, can change algal lipid metabolism and how adaptation may take place. PMID:16492482

Guschina, Irina A; Harwood, John L

2006-03-01

35

Lipid Droplets And Cellular Lipid Metabolism  

PubMed Central

Among organelles, lipid droplets (LDs) uniquely constitute a hydrophobic phase in the aqueous environment of the cytosol. Their hydrophobic core of neutral lipids stores metabolic energy and membrane components, making LDs hubs for lipid metabolism. In addition, LDs are implicated in a number of other cellular functions, ranging from protein storage and degradation to viral replication. These processes are functionally linked to many physiological and pathological conditions, including obesity and related metabolic diseases. Despite their important functions and nearly ubiquitous presence in cells, many aspects of LD biology are unknown. In the past few years, the pace of LD investigation has increased, providing new insights. Here, we review the current knowledge of LD cell biology and its translation to physiology. PMID:22524315

Walther, Tobias C.; Farese, Robert V.

2013-01-01

36

Seaweed Lipids as Nutraceuticals  

Microsoft Academic Search

Seaweeds are known as low-energy food. Despite low lipid content, ?-3 and ?-6 polyunsaturated fatty acids (PUFAs) introduce a significant part of seaweed lipids. PUFAs are the important components of all cell membranes and precursors of eicosanoids that are essential bioregulators of many cellular processes. PUFAs effectively reduce the risk of cardiovascular diseases, cancer, ostheoporosis, and diabetes. Because of the

Ladislava Mišurcová; Jarmila Ambrožová; Dušan Samek

2011-01-01

37

Lipids: Absorption and transport  

Technology Transfer Automated Retrieval System (TEKTRAN)

Lipid has long been recognized as an important dietary component. Dietary lipid (fat) is a critical source of metabolic energy and a substrate for the synthesis of metabolically active compounds (essential fatty acids), and serves as a carrier for other nutrients such as the fat-soluble vitamins A, ...

38

Lipids of Mentha spicata  

Microsoft Academic Search

The levels of lipids, pigments, and essential oil and the lipid and fatty acid compositions of individual organs of freshly gatheredMentha spicata plants have been established. It has been found that the organs studied have a complex qualitative composition of the extractive substances but differ in their levels of individual groups of substances and components.

T. V. Khomova; S. D. Gusakova; A. Nigmatullaev

1997-01-01

39

Lipid oxidation in foods  

Microsoft Academic Search

This review discusses the basic chemical reactions that affect food flavor quality. Although there are many reactions that can lead to the deterioration of quality in foods, this review focuses on lipid oxidation and how it adversely affects flavor principles. It also presents technological advances for studying the basic mechanism of lipid oxidation, for measuring its intensity, and for retaining

Allen J. St. Angelo; John Vercellotti; Tom Jacks; Michael Legendre

1996-01-01

40

Composite Slayer lipid structures  

Microsoft Academic Search

Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at meso- and macroscopic scale. In this review, we provide a state of the

Bernhard Schuster; Uwe B. Sleytr

2009-01-01

41

The evolution of lipids.  

PubMed

Living organisms on the Earth which are divided into three major domains--Archaea, Bacteria, and Eucarya, probably came from a common ancestral cell. Because there are many thermophilic microorganisms near the root of the universal phylogenetic tree, the common ancestral cell should be considered to be a thermophilic microorganism. The existence of a cell is necessary for the living organisms; the cell membrane is the essential structural component of a cell, so its amphiphilic property is vital for the molecule of lipids for cell membranes. Tetraether type glycerophospholipids with C40 isoprenoid chains are major membrane lipids widely distributed in archaeal cells. Cyclization number of C40 isoprenoid chains in thermophilic archaea influences the fluidity of lipids whereas the number of carbons and degree of unsaturation in fatty acids do so in bacteria and eucarya. In addition to the cyclization of the tetraether lipids, covalent bonding of two C40 isoprenoid chains was found in hyperthermophiles. These characteristic structures of the lipids seem to contribute to their fundamental physiological roles in hyperthermophiles. Stereochemical differences between G-1-P archaeal lipids and G-3-P bacterial and eucaryal lipids might have occurred by the function of some proteins long after the first cell was developed by the reactions of small organic molecules. We propose that the structure of lipids of the common ancestral cell may have been similar to those of hyperthermophilic archaea. PMID:11803978

Itoh, Y H; Sugai, A; Uda, I; Itoh, T

2001-01-01

42

Lipid-absorbing Polymers  

NASA Technical Reports Server (NTRS)

The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

Marsh, H. E., Jr.; Wallace, C. J.

1973-01-01

43

PHYSIOLOGY: Unfolding Lipid Metabolism  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required: A transcription factor exhibits dual roles, regulating genes that respond to improperly folded proteins and genes that control lipid synthesis.

Jay D. Horton (University of Texas Southwestern Medical Center at Dallas; Departments of Molecular Genetics and Internal Medicine)

2008-06-13

44

Metabolism. Part III: Lipids.  

ERIC Educational Resources Information Center

Describes the metabolic processes of complex lipids, including saponification, activation and transport, and the beta-oxidation spiral. Discusses fatty acid degradation in regard to biochemical energy and ketone bodies. (TW)

Bodner, George M.

1986-01-01

45

Lipids in human milk  

Microsoft Academic Search

I have reviewed recent (March 1995–December 1997) papers on human milk lipids including many on fatty acid (FA) composition.\\u000a The effects of maternal diets on the profiles are apparent. However, more data on the composition of milk lipids are needed.\\u000a It is noteworthy that so few papers on milk FA composition have reported analyses using high-resolution gas-liquid chromatography\\u000a columns. Two

Robert G. Jensen

1999-01-01

46

Focus Issue: Signaling Lipids  

NSDL National Science Digital Library

Membranes are dynamic and specific contributors to cell signaling. Cellular membranes play a key structural role in creating sites for the formation of signaling complexes. Changes in membrane phospholipids can regulate the activity of transmembrane and peripheral membrane proteins. Modification of membrane lipids can result in formation of dynamic signaling molecules. Science's STKE highlights new insights into the roles that lipids and membranes play in cell signaling.

Nancy R. Gough (American Association for the Advancement of Science;Science's STKE REV)

2006-02-07

47

Journal of Lipid Research  

NSDL National Science Digital Library

The Journal of Lipid Research (JLR)publishes "original articles and invited reviews on subjects involving lipids in any scientific discipline, including clinical and morphological studies." Online full-text content begins with the January 1998 issue, and will expand with each month's new issues. Online abstracts begin with the July 1965 issue. The site is produced in conjunction with Stanford University's HighWire Press.

48

Acyl-Lipid Metabolism  

PubMed Central

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

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

49

Acyl-Lipid Metabolism  

PubMed Central

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

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

50

Lipid membranes for membrane proteins.  

PubMed

The molecular dynamics (MD) simulation of membrane proteins requires the setup of an accurate representation of lipid bilayers. This chapter describes the setup of a lipid bilayer system from scratch using generally available tools, starting with a definition of the lipid molecule POPE, generation of a lipid bilayer, energy minimization, MD simulation, and data analysis. The data analysis includes the calculation of area and volume per lipid, deuterium order parameters, self-diffusion constant, and the electron density profile. PMID:25330959

Kukol, Andreas

2015-01-01

51

Lipid-lowering drugs.  

PubMed

Although a change in life-style is often the method of first choice for lipid lowering, lipid-lowering drugs, in general, help to control elevated levels of different forms of lipids in patients with hyperlipidemia. While one group of drugs, statins, lowers cholesterol, the other group, fibrates, is known to take care of fatty acids and triglycerides. In addition, other drugs, such as ezetimibe, colesevelam, torcetrapib, avasimibe, implitapide, and niacin are also being considered to manage hyperlipidemia. As lipids are very critical for cardiovascular diseases, these drugs reduce fatal and nonfatal cardiovascular abnormalities in the general population. However, a number of recent studies indicate that apart from their lipid-lowering activities, statins and fibrates exhibit multiple functions to modulate intracellular signaling pathways, inhibit inflammation, suppress the production of reactive oxygen species, and modulate T cell activity. Therefore, nowadays, these drugs are being considered as possible therapeutics for several forms of human disorders including cancer, autoimmunity, inflammation, and neurodegeneration. Here I discuss these applications in the light of newly discovered modes of action of these drugs. PMID:16568248

Pahan, K

2006-05-01

52

Immobilized lipid-bilayer materials  

DOEpatents

A method for preparing encapsulated lipid-bilayer materials in a silica matrix comprising preparing a silica sol, mixing a lipid-bilayer material in the silica sol and allowing the mixture to gel to form the encapsulated lipid-bilayer material. The mild processing conditions allow quantitative entrapment of pre-formed lipid-bilayer materials without modification to the material's spectral characteristics. The method allows for the immobilization of lipid membranes to surfaces. The encapsulated lipid-bilayer materials perform as sensitive optical sensors for the detection of analytes such as heavy metal ions and can be used as drug delivery systems and as separation devices.

Sasaki, Darryl Y. (Albuquerque, NM); Loy, Douglas A. (Albuquerque, NM); Yamanaka, Stacey A. (Dallas, TX)

2000-01-01

53

Direct Visualization of Lipid Phase Segregation in Single Lipid Bilayers  

E-print Network

Direct Visualization of Lipid Phase Segregation in Single Lipid Bilayers with Coherent Anti. Visualization of the different phases requires the addition of fluorescent compounds that have either. To rule out any artifacts, a clear visualization of lipid domains in free-standing bilayers without

Potma, Eric Olaf

54

Lipid nanotube or nanowire sensor  

DOEpatents

A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

Noy, Aleksandr (Belmont, CA); Bakajin, Olgica (San Leandro, CA); Letant, Sonia (Livermore, CA); Stadermann, Michael (Dublin, CA); Artyukhin, Alexander B. (Menlo Park, CA)

2009-06-09

55

Lipids: Absorption and transport  

Technology Transfer Automated Retrieval System (TEKTRAN)

Due to the hydrophobic nature of lipids, dietary fat is handled differently than protein or carbohydrate with respect with digestion and absorption. Dietary fats are broken down throughout the gastrointestinal system. A unique group of enzymes and cofactors allows this process to proceed in an eff...

56

Lipid rafts and signal transduction  

Microsoft Academic Search

Signal transduction is initiated by complex protein–protein interactions between ligands, receptors and kinases, to name only a few. It is now becoming clear that lipid micro-environments on the cell surface — known as lipid rafts — also take part in this process. Lipid rafts containing a given set of proteins can change their size and composition in response to intra-

Kai Simons; Derek Toomre

2000-01-01

57

Topological regulation of lipid balance in cells.  

PubMed

Lipids are unevenly distributed within and between cell membranes, thus defining organelle identity. Such distribution relies on local metabolic branches and mechanisms that move lipids. These processes are regulated by feedback mechanisms that decipher topographical information in organelle membranes and then regulate lipid levels or flows. In the endoplasmic reticulum, the major lipid source, transcriptional regulators and enzymes sense changes in membrane features to modulate lipid production. At the Golgi apparatus, lipid-synthesizing, lipid-flippase, and lipid-transport proteins (LTPs) collaborate to control lipid balance and distribution within the membrane to guarantee remodeling processes crucial for vesicular trafficking. Open questions exist regarding LTPs, which are thought to be lipid sensors that regulate lipid synthesis or carriers that transfer lipids between organelles across long distances or in contact sites. A novel model is that LTPs, by exchanging two different lipids, exploit one lipid gradient between two distinct membranes to build a second lipid gradient. PMID:24606148

Drin, Guillaume

2014-01-01

58

Lipids and lipid modifications in the regulation of membrane traffic  

PubMed Central

SUMMARY Lipids play a multitude of roles in intracellular protein transport and membrane traffic. While a large body of data implicates phosphoinositides in these processes, much less is known about other glycerophospholipids, such as phosphatidic acid, diacylglycerol, and phosphatidylserine. Growing evidence suggests that these lipids may also play an important role, either by mediating protein recruitment to membranes or by directly affecting membrane dynamics. Although membrane lipids are believed to be organized in microdomains, recent advances in cellular imaging methods paired with sophisticated reporters and proteomic analysis have led to the formulation of alternative ideas regarding the characteristics and putative functions of lipid microdomains and their associated proteins. In fact the traditional view that membrane proteins may freely diffuse in a large ‘sea of lipids’ may need to be revised. Lastly, modifications of proteins by lipids or related derivatives have surprisingly complex roles on regulated intracellular transport of a wide range of molecules. PMID:17651957

Haucke, Volker; Di Paolo, Gilbert

2007-01-01

59

Biogenesis of the multifunctional lipid droplet: Lipids, proteins, and sites  

PubMed Central

Lipid droplets (LDs) are ubiquitous dynamic organelles that store and supply lipids in all eukaryotic and some prokaryotic cells for energy metabolism, membrane synthesis, and production of essential lipid-derived molecules. Interest in the organelle’s cell biology has exponentially increased over the last decade due to the link between LDs and prevalent human diseases and the discovery of new and unexpected functions of LDs. As a result, there has been significant recent progress toward understanding where and how LDs are formed, and the specific lipid pathways that coordinate LD biogenesis. PMID:24590170

Gross, Steven P.

2014-01-01

60

Lipid classification, structures and tools?  

PubMed Central

The study of lipids has developed into a research field of increasing importance as their multiple biological roles in cell biology, physiology and pathology are becoming better understood. The Lipid Metabolites and Pathways Strategy (LIPID MAPS) consortium is actively involved in an integrated approach for the detection, quantitation and pathway reconstruction of lipids and related genes and proteins at a systems-biology level. A key component of this approach is a bioinformatics infrastructure involving a clearly defined classification of lipids, a state-of-the-art database system for molecular species and experimental data and a suite of user-friendly tools to assist lipidomics researchers. Herein, we discuss a number of recent developments by the LIPID MAPS bioinformatics core in pursuit of these objectives. This article is part of a Special Issue entitled Lipodomics and Imaging Mass Spectrometry. PMID:21704189

Fahy, Eoin; Cotter, Dawn; Sud, Manish; Subramaniam, Shankar

2012-01-01

61

Lipid metabolism in mitochondrial membranes.  

PubMed

Mitochondrial membranes have a unique lipid composition necessary for proper shape and function of the organelle. Mitochondrial lipid metabolism involves biosynthesis of the phospholipids phosphatidylethanolamine, cardiolipin and phosphatidylglycerol, the latter is a precursor of the late endosomal lipid bis(monoacylglycero)phosphate. It also includes mitochondrial fatty acid synthesis necessary for the formation of the lipid cofactor lipoic acid. Furthermore the synthesis of coenzyme Q takes place in mitochondria as well as essential parts of the steroid and vitamin D metabolism. Lipid transport and remodelling, which are necessary for tailoring and maintaining specific membrane properties, are just partially unravelled. Mitochondrial lipids are involved in organelle maintenance, fission and fusion, mitophagy and cytochrome c-mediated apoptosis. Mutations in TAZ, SERAC1 and AGK affect mitochondrial phospholipid metabolism and cause Barth syndrome, MEGDEL and Sengers syndrome, respectively. In these disorders an abnormal mitochondrial energy metabolism was found, which seems to be due to disturbed protein-lipid interactions, affecting especially enzymes of the oxidative phosphorylation. Since a growing number of enzymes and transport processes are recognised as parts of the mitochondrial lipid metabolism, a further increase of lipid-related disorders can be expected. PMID:25082432

Mayr, Johannes A

2015-01-01

62

ANALYSIS OF POLAR LIPIDS FROM OAT GROATS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Oats are a rich source of polar lipids and oat polar lipids are being applied to some unique applications. However, many characteristics of polar oat lipid composition have not yet been characterized with modern methodology. Our objective was to identify constitutive lipids of the polar lipid fracti...

63

Mannosylerythritol lipids: a review.  

PubMed

Mannosylerythritol lipids (MELs) are surface active compounds that belong to the glycolipid class of biosurfactants (BSs). MELs are produced by Pseudozyma sp. as a major component while Ustilago sp. produces them as a minor component. Although MELs have been known for over five decades, they recently regained attention due to their environmental compatibility, mild production conditions, structural diversity, self-assembling properties and versatile biochemical functions. In this review, the MEL producing microorganisms, the production conditions, their applications, their diverse structures and self-assembling properties are discussed. The biosynthetic pathways and the regulatory mechanisms involved in the production of MEL are also explained here. PMID:18716809

Arutchelvi, Joseph Irudayaraj; Bhaduri, Sumit; Uppara, Parasu Veera; Doble, Mukesh

2008-12-01

64

TRPC channel lipid specificity and mechanisms of lipid regulation  

PubMed Central

TRPC channels are a subset of the transient receptor potential (TRP) proteins widely expressed in mammalian cells. They are thought to be primarily involved in determining calcium or sodium entry and have broad-ranging functions that include regulation of cell proliferation, motility and contraction. The channels do not respond to a single stimulator but rather are activated or modulated by a multiplicity of factors, potentially existing as integrators at the plasma membrane. This review considers the sensitivity of TRPCs to lipid factors, with focus on sensitivities to diacylglycerols, lysophospholipids, arachidonic acid and its metabolites, sphingosine-1-phosphate (S1P), cholesterol and derivatives, and other lipid factors such as gangliosides. Promiscuous and selective lipid-sensing are apparent. In many cases the lipids stimulate channel function or increase insertion of channels in the membrane. Both direct and indirect (receptor-dependent) lipid effects are evident. Although information is limited, the lipid profiles are consistent with TRPCs having close working relationships with phospholipase C and A2 enzymes. We need much more information about lipid-sensing by TRPCs if we are to fully appreciate its significance, but the available data suggest that lipid-sensing is a key, but not exclusive, aspect of TRPC biology. PMID:19324410

Beech, David J.; Bahnasi, Yahya M.; Dedman, Alexandra M.; AL-Shawaf, Eman

2009-01-01

65

Polar lipids from oat kernels  

Technology Transfer Automated Retrieval System (TEKTRAN)

Oat (Avena sativa L.) kernels appear to contain much higher polar lipid concentrations than other plant tissues. We have extracted, identified, and quantified polar lipids from 18 oat genotypes grown in replicated plots in three environments in order to determine genotypic or environmental variation...

66

Membrane lipid domains in the nervous system.  

PubMed

The structural properties of the lipids forming biological membranes determine a very high level of lateral organization within membranes. Lipid-driven membrane organization allows the segregation of membrane-associated components into membrane lipid domains, now worldwide known as lipid rafts, acting as dynamic platforms for signal transduction, protein processing and membrane turnover. Many processes necessary to the correct functions of nervous system occur in lipid rafts and are dependent on lipid raft organization. Thus, an altered lipid composition frequently occurring in neurodegenerative diseases leads to anomalous lipid raft organization and then to deregulated cell signaling. PMID:25553451

Sonnino, Sandro; Aureli, Massimo; Mauri, Laura; Ciampa, Maria Grazia; Prinetti, Alessandro

2015-01-01

67

Crystallizing Membrane Proteins in Lipidic Mesophases. A Host Lipid Screen  

PubMed Central

The default lipid for the bulk of the crystallogenesis studies performed to date using the cubic mesophase method is monoolein. There is no good reason however, why this 18-carbon, cis-monounsaturated monoacylglycerol should be the preferred lipid for all target membrane proteins. The latter come from an array of biomembrane types with varying properties that include hydrophobic thickness, intrinsic curvature, lateral pressure profile, lipid and protein makeup, and compositional asymmetry. Thus, it seems reasonable that screening for crystallizability based on the identity of the lipid creating the hosting mesophase would be worthwhile. For this, monoacylglycerols with differing acyl chain characteristics, such as length and olefinic bond position, must be available. A lipid synthesis and purification program is in place in the author's laboratory to serve this need. In the current study with the outer membrane sugar transporter, OprB, we demonstrate the utility of host lipid screening as a means for generating diffraction-quality crystals. Host lipid screening is likely to prove a generally useful strategy for mesophase-based crystallization of membrane proteins. PMID:21743796

Li, Dianfan; Lee, Jean; Caffrey, Martin

2011-01-01

68

Phosphonate lipid tubules II.  

PubMed

We describe a new chiral tubule-forming lipid in which the C-O-P phosphoryl linkage of the archetypal tubule-forming molecule, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine, "DC(8,9)PC", is replaced by a C-P linkage. Tubule formation with this phosphonate analogue proceeds under the same mild conditions as with DC(8,9)PC and produces similar yields, but synchrotron small-angle X-ray scattering, atomic force microscopy, and optical microscopy show the new tubules to have diameters 1.94 times as great, to be significantly shorter, and to be thinner-walled. A significant portion of the enantiomerically pure chiral phosphonate precipitate is in the form of stable open helices, and these helices are divided almost evenly between left- and right-handed members. PMID:11841291

Thomas, Britt N; Lindemann, Christopher M; Corcoran, Robert C; Cotant, Casey L; Kirsch, Janet E; Persichini, Phillip J

2002-02-20

69

Renal lipid metabolism and lipotoxicity  

PubMed Central

Purpose of review Lipid accumulation in nonadipose tissues is increasingly recognized to contribute to organ injury through a process termed lipotoxicity, but whether this process occurs in the kidney is still uncertain. This article briefly summarizes the normal role of lipids in renal physiology and the current evidence linking excess lipids and lipotoxicity to renal dysfunction. Recent findings Evidence suggesting that renal lipid accumulation and lipotoxicity may lead to kidney dysfunction has mounted significantly over recent years. Abnormal renal lipid content has been described in a number of animal models and has been successfully manipulated using pharmacologic or genetic strategies. There is some heterogeneity among studies with regard to the mechanisms, consequences, and localization of lipid accumulation in the kidney, explainable at least in part by inherent differences between animal models. The relevance of these findings for human pathophysiology remains to be established. Summary Current knowledge on renal lipid physiology and pathophysiology is insufficient, but provides a strong foundation and incentive for further exploration. The future holds significant challenges in this area, especially with regard to applicability of research findings to the human kidney in vivo, but also the opportunity to transform our understanding of an array of kidney disorders. PMID:20489613

Bobulescu, Ion Alexandru

2011-01-01

70

Hybrid lipid-based nanostructures  

NASA Astrophysics Data System (ADS)

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.

Dayani, Yasaman

71

Lipid dynamics at dendritic spines  

PubMed Central

Dynamic changes in the structure and composition of the membrane protrusions forming dendritic spines underlie memory and learning processes. In recent years a great effort has been made to characterize in detail the protein machinery that controls spine plasticity. However, we know much less about the involvement of lipids, despite being major membrane components and structure determinants. Moreover, protein complexes that regulate spine plasticity depend on specific interactions with membrane lipids for proper function and accurate intracellular signaling. In this review we gather information available on the lipid composition at dendritic spine membranes and on its dynamics. We pay particular attention to the influence that spine lipid dynamism has on glutamate receptors, which are key regulators of synaptic plasticity. PMID:25152717

Dotti, Carlos Gerardo; Esteban, Jose Antonio; Ledesma, María Dolores

2014-01-01

72

Dietary lipids and cancer.  

PubMed

Cancer is one of the main causes of death in Western countries. Among the factors that contribute to the appearance of this disease, diet has a fundamental role, and specifically fats are the main component related to the increase in the incidence of cancerous diseases, particularly breast, colon-rectal, and prostate cancer. From dietary lipids, much attention has been given to the beneficial effects of fish oil, rich in polyunsaturated fatty acids n-3 serie, as well as of olive oil, rich in monounsaturated fatty acids--primarily oleic acid. On the contrary, a negative effect has been reported for polyunsaturated fatty acids n-6 serie and for saturated fatty acids. Nutrition constitutes an important aspect of the life of cancer patients. Currently, nutritional formulas are being designed with supplements of polyunsaturated n-3 fatty acids and other components such as arginine, RNA, lysine, etc., with the aim of ameliorating the effects of this pathology. The results demonstrate the lower morbility and therefore improved quality of life, a decline in mortality, and a reduction in related costs. PMID:16771072

Granados, S; Quiles, J L; Gil, A; Ramírez-Tortosa, M C

2006-05-01

73

Pathogens, toxins, and lipid rafts  

Microsoft Academic Search

Summary The plasma membrane is not a uniform two-dimensional space but includes various types of specialized regions containing specific lipids and proteins. These include clathrin-coated pits and caveolae. The existence of other cholesterol- and glycosphingolipid-rich microdomains has also been proposed. The aim of this review is to illustrate that these latter domains, also called lipid rafts, may be the preferential

M. Fivaz; L. Abrami; F. G. van der Goot

2000-01-01

74

Lipid Mediator Mechanisms in Fish  

Microsoft Academic Search

Salmonids synthesize platelet-activating factor (PAF: 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine), and much of the interest in the potential use of lipids to mediate physiological events in fish metabolism is focused on this compound. In sharp contrast to mammalian cells, salmonid cells acylate lysoPAF with a high degree of specificity for omega-3 fatty acids. Polyunsaturated fatty acids in the lipids in tissues of rainbow trout

B. L. Samples; G. L. Pool; G. I. Pritchard; R. H. Lumb

1997-01-01

75

LIPIDS OF SARCINA LUTEA I.  

PubMed Central

Huston, Charles K. (U.S. Army Biological Laboratories, Fort Detrick, Frederick, Md.), and Phillip W. Albro. Lipids of Sarcina lutea. I. Fatty acid composition of the extractable lipids. J. Bacteriol. 88:425–432. 1964.—The extractable lipids of Sarcina lutea were separated into several fractions by a combination of column and thin-layer chromatography. Qualitative and quantitative characterization of the fatty acid content of these lipid fractions was accomplished by means of gas-liquid chromatography and infrared analyses. Of the total extract, the lipids consisted of 2.1% free fatty acids, 51.0% glycerides, and 22.7% complex lipids; they had a fatty acid content with a complete spectrum of carbon numbers from C8 to C22. The fatty acids included a large component of branched-acids in addition to the normal straight-chain acids. The branched-acids, comprising 40% of the fatty acids analyzed, constituted a homologous series of iso-acids from C12 to C19. Two 18-carbon unsaturates were found cis-9-octadecenoate and cis-11-octadecenoate. A relatively high percentage (20.5%) of the extractable material from S. lutea was found to be hydrocarbon. This material was not further characterized. PMID:14203360

Huston, Charles K.; Albro, Phillip W.

1964-01-01

76

Lipid interactions during virus entry and infection  

PubMed Central

Summary For entry and infection viruses have developed numerous strategies to subjugate indispensable cellular factors and functions. Host cell lipids and cellular lipid synthesis machinery are no exception. Not only do viruses exploit existing lipid signalling and modifications for virus entry and trafficking, they also reprogram lipid synthesis, metabolism, and compartmentalization for assembly and egress. Here we review these various concepts and highlight recent progress in understanding viral interactions with host cell lipids during entry and assembly. PMID:25131438

Mazzon, Michela; Mercer, Jason

2014-01-01

77

Periodic Structures in Lipid Monolayer Phase Transitions  

NASA Astrophysics Data System (ADS)

Periodic patterns are observed when supported lipid monolayers doped with low concentrations of fluorescent lipid probes are observed with epi-fluorescence microscopy. Monolayers of dipalmitoyl phosphatidylcholine were examined on air--water interfaces and also on alkylated glass coverslips. The patterns are formed by periodic arrays of solid-phase lipid domains in equilibrium with fluid-phase lipid under specified conditions of temperature and two-dimensional lipid pressure. Electrostatic forces may stabilize the periodic ordering of the solid domains.

McConnell, Harden M.; Tamm, Lukas K.; Weis, Robert M.

1984-05-01

78

Lipid bilayers on nano-templates  

DOEpatents

A lipid bilayer on a nano-template comprising a nanotube or nanowire and a lipid bilayer around the nanotube or nanowire. One embodiment provides a method of fabricating a lipid bilayer on a nano-template comprising the steps of providing a nanotube or nanowire and forming a lipid bilayer around the polymer cushion. One embodiment provides a protein pore in the lipid bilayer. In one embodiment the protein pore is sensitive to specific agents

Noy, Aleksandr (Belmont, CA); Artyukhin, Alexander B. (Menlo Park, CA); Bakajin, Olgica (San Leandro, CA); Stoeve, Pieter (Davis, CA)

2009-08-04

79

Fsp27 promotes lipid droplet growth by lipid exchange and transfer at lipid droplet contact sites  

PubMed Central

Lipid droplets (LDs) are dynamic cellular organelles that control many biological processes. However, molecular components determining LD growth are poorly understood. Genetic analysis has indicated that Fsp27, an LD-associated protein, is important in controlling LD size and lipid storage in adipocytes. In this paper, we demonstrate that Fsp27 is focally enriched at the LD–LD contacting site (LDCS). Photobleaching revealed the occurrence of lipid exchange between contacted LDs in wild-type adipocytes and Fsp27-overexpressing cells but not Fsp27-deficient adipocytes. Furthermore, live-cell imaging revealed a unique Fsp27-mediated LD growth process involving a directional net lipid transfer from the smaller to larger LDs at LDCSs, which is in accordance with the biophysical analysis of the internal pressure difference between the contacting LD pair. Thus, we have uncovered a novel molecular mechanism of LD growth mediated by Fsp27. PMID:22144693

Gong, Jingyi; Sun, Zhiqi; Wu, Lizhen; Xu, Wenyi; Schieber, Nicole; Xu, Dijin; Shui, Guanghou; Yang, Hongyuan; Parton, Robert G.

2011-01-01

80

The Lipids of Pneumocystis carinii  

PubMed Central

Information about a number of Pneumocystis carinii lipids obtained by the analyses of organisms isolated and purified from infected lungs of corticosteroid-immunosuppressed rats has been reported in recent years. Of the common opportunistic protists associated with AIDS (Cryptosporidium, Toxoplasma, and the microsporidia), more is currently known about the lipids of P. carinii than the others. Lipids that are synthesized by the organism but not by humans are attractive targets for drug development. Thus, the elucidation of ?7C-24-alykylated sterol and cis-9,10-epoxystearic acid biosyntheses in P. carinii is currently being examined in detail, since these have been identified as P. carinii-specific lipids. The development of low-toxicity drugs that prevent sterol C-24 alkylation and the specific inhibition of the lipoxygenase that forms cis-9,10-epoxystearic acid might prove fruitful. Although humans can synthesize coenzyme Q10, the anti-P. carinii activity and low toxicity of ubiquinone analogs such as atovaquone suggest that the electron transport chain in the pathogen may differ importantly from that in the host. Although resistance to atovaquone has been observed, development of other naphthoquinone drugs would provide a broader armamentarium of drugs to treat patients with P. carinii pneumonia. Studies of bronchoalveolar lavage fluid and of infected lungs have demonstrated that the infection causes a number of chemical abnormalities. Bronchoalveolar lavage fluid obtained after the removal of lung cellular material and the organisms has been shown to contain larger amounts of surfactant proteins and smaller amounts of phospholipids than do comparable samples from P. carinii-free lungs. Increased phospholipase activity, inhibition of surfactant secretion by type II cells, and uptake and catabolism of lipids by the pathogen may explain this phenomenon related to P. carinii pneumonia. Although not yet thoroughly examined, initial studies on the uptake and metabolism of lipids by P. carinii suggest that the organism relies heavily on exogenous lipid nutrients. PMID:9457427

Kaneshiro, Edna S.

1998-01-01

81

Mass Spectrometry Methodology in Lipid Analysis  

PubMed Central

Lipidomics is an emerging field, where the structures, functions and dynamic changes of lipids in cells, tissues or body fluids are investigated. Due to the vital roles of lipids in human physiological and pathological processes, lipidomics is attracting more and more attentions. However, because of the diversity and complexity of lipids, lipid analysis is still full of challenges. The recent development of methods for lipid extraction and analysis and the combination with bioinformatics technology greatly push forward the study of lipidomics. Among them, mass spectrometry (MS) is the most important technology for lipid analysis. In this review, the methodology based on MS for lipid analysis was introduced. It is believed that along with the rapid development of MS and its further applications to lipid analysis, more functional lipids will be identified as biomarkers and therapeutic targets and for the study of the mechanisms of disease. PMID:24921707

Li, Lin; Han, Juanjuan; Wang, Zhenpeng; Liu, Jian’an; Wei, Jinchao; Xiong, Shaoxiang; Zhao, Zhenwen

2014-01-01

82

Lipid Metabolism, Apoptosis and Cancer Therapy  

PubMed Central

Lipid metabolism is regulated by multiple signaling pathways, and generates a variety of bioactive lipid molecules. These bioactive lipid molecules known as signaling molecules, such as fatty acid, eicosanoids, diacylglycerol, phosphatidic acid, lysophophatidic acid, ceramide, sphingosine, sphingosine-1-phosphate, phosphatidylinositol-3 phosphate, and cholesterol, are involved in the activation or regulation of different signaling pathways. Lipid metabolism participates in the regulation of many cellular processes such as cell growth, proliferation, differentiation, survival, apoptosis, inflammation, motility, membrane homeostasis, chemotherapy response, and drug resistance. Bioactive lipid molecules promote apoptosis via the intrinsic pathway by modulating mitochondrial membrane permeability and activating different enzymes including caspases. In this review, we discuss recent data in the fields of lipid metabolism, lipid-mediated apoptosis, and cancer therapy. In conclusion, understanding the underlying molecular mechanism of lipid metabolism and the function of different lipid molecules could provide the basis for cancer cell death rationale, discover novel and potential targets, and develop new anticancer drugs for cancer therapy. PMID:25561239

Huang, Chunfa; Freter, Carl

2015-01-01

83

Lipid metabolism in prostate cancer  

PubMed Central

The malignant transformation of cells requires adaptations across multiple metabolic processes to satisfy the energy required for their increased rate of proliferation. Dysregulation of lipid metabolism has been a hallmark of the malignant phenotype; increased lipid accumulation secondary to changes in the levels of a variety of lipid metabolic enzymes has been documented in a variety of tumors, including prostate. Alterations in prostate lipid metabolism include upregulation of several lipogenic enzymes as well as of enzymes that function to oxidize fatty acids as an energy source. Cholesterol metabolism and phospholipid metabolism are also affected. With respect to lipogenesis, most studies have concentrated on increased expression and activity ofthe de novo fatty acid synthesis enzyme, fatty acid synthase (FASN), with suggestions that FASN might function as an oncogene. A central role for fatty acid oxidation in supplying energy to the prostate cancer cell is supported by the observation that the peroxisomal enzyme, ?-methylacyl-CoA racemase (AMACR), which facilitates the transformation of branched chain fatty acids to a form suitable for ?-oxidation, is highly overexpressed in prostate cancer compared with normal prostate. Exploitation of the alterations in lipid metabolic pathways in prostate cancer could result in the development of new therapeutic modalities as well as provide candidates for new prognostic and predictive biomarkers. AMACR has already proven to be a valuable biomarker in distinguishing normal from malignant prostate tissue, and is used routinely in clinical practice. PMID:25374912

Wu, Xinyu; Daniels, Garrett; Lee, Peng; Monaco, Marie E

2014-01-01

84

It’s a lipid’s world: Bioactive lipid metabolism and signaling in neural stem cell differentiation  

PubMed Central

Lipids are often considered membrane components whose function is to embed proteins into cell membranes. In the last two decades, studies on brain lipids have unequivocally demonstrated that many lipids have critical cell signaling functions; they are called “bioactive lipids”. Pioneering work in Dr. Robert Ledeen’s laboratory has shown that two bioactive brain sphingolipids, sphingomyelin and the ganglioside GM1 are major signaling lipids in the nuclear envelope. In addition to derivatives of the sphingolipid ceramide, the bioactive lipids discussed here belong to the classes of terpenoids and steroids, eicosanoids, and lysophospholipids. These lipids act mainly through two mechanisms: 1) direct interaction between the bioactive lipid and a specific protein binding partner such as a lipid receptor, protein kinase or phosphatase, ion exchanger, or other cell signaling protein; and 2) formation of lipid microdomains or rafts that regulate the activity of a group of raft-associated cell signaling proteins. In recent years, a third mechanism has emerged, which invokes lipid second messengers as a regulator for the energy and redox balance of differentiating neural stem cells (NSCs). Interestingly, developmental niches such as the stem cell niche for adult NSC differentiation may also be metabolic compartments that respond to a distinct combination of bioactive lipids. The biological function of these lipids as regulators of NSC differentiation will be reviewed and their application in stem cell therapy discussed. PMID:22246226

Bieberich, Erhard

2012-01-01

85

HDL lipids and insulin resistance.  

PubMed

There is renewed interest in high-density lipoproteins (HDLs) due to recent findings linking atherosclerosis to the formation of dysfunctional HDL. This article focuses on the universe of HDL lipids and their potential protective or proinflammatory roles in vascular disease and insulin resistance. HDL carries a wide array of lipids including sterols, triglycerides, fat-soluble vitamins, and a large number of phospholipids, including phosphatidylcholine, sphingomyelin, and ceramide with many biological functions. Ceramide has been implicated in the pathogenesis of insulin resistance and has many proinflammatory properties. In contrast, sphingosine-1-phosphate, which is transported mainly in HDL, has anti-inflammatory properties that may be atheroprotective and may account for some of the beneficial effects of HDL. However, the complexity of the HDL lipidome is only beginning to reveal itself. The emergence of new analytical technologies should rapidly increase our understanding of the function of HDL lipids and their role in disease states. PMID:20425071

Hoofnagle, Andrew N; Vaisar, Tomas; Mitra, Poulami; Chait, Alan

2010-02-01

86

The Membrane and Lipids as Integral Participants in Signal Transduction: Lipid Signal Transduction for the Non-lipid Biochemist  

NSDL National Science Digital Library

This review seeks to explore the magnitude and diversity of the roles of the cell membrane and lipids in signal transduction and to highlight the interrelatedness of families of lipid mediators in signal transduction

Kathleen M. Eyster (Sanford School of Medicine, University of South Dakota Division of Basic Biomedical Sciences)

2007-03-01

87

Charge-reversal Lipids, Peptide-based Lipids, and Nucleoside-based Lipids for Gene Delivery  

PubMed Central

Conspectus Twenty years after gene therapy was introduced in the clinic, advances in the technique continue to garner headlines as successes pique the interest of clinicians, researchers, and the public. Gene therapy’s appeal stems from its potential to revolutionize modern medical therapeutics by offering solutions to a myriad of diseases by tailoring the treatment to a specific individual’s genetic code. Both viral and non-viral vectors have been used in the clinic, but the low transfection efficiencies when utilizing non-viral vectors have lead to an increased focus on engineering new gene delivery vectors. To address the challenges facing non-viral or synthetic vectors, specifically lipid-based carriers, we have focused on three main themes throughout our research: 1) that releasing the nucleic acid from the carrier will increase gene transfection; 2) that utilizing biologically inspired designs, such as DNA binding proteins, to create lipids with peptide-based headgroups will improve delivery; and 3) that mimicking the natural binding patterns observed within DNA, by using lipids having a nucleoside headgroup, will give unique supramolecular assembles with high transfection efficiency. The results presented in this Account demonstrate that cellular uptake and transfection efficacy can be improved by engineering the chemical components of the lipid vectors to enhance nucleic acid binding and release kinetics. Specifically, our research has shown that the incorporation of a charge-reversal moiety to initiate change of the lipid from positive to negative net charge during the transfection process improves transfection. In addition, by varying the composition of the spacer (rigid, flexible, short, long, and aromatic) between the cationic headgroup and the hydrophobic chains, lipids can be tailored to interact with different nucleic acids (DNA, RNA, siRNA) and accordingly affect delivery, uptake outcomes, and transfection efficiency. Introduction of a peptide headgroup into the lipid provides a mechanism to affect the binding of the lipid to the nucleic acid, to influence the supramolecular lipoplex structure, and to enhance gene transfection activity. Lastly, we discuss the in-vitro successes we have had when using lipids possessing a nucleoside headgroup to create unique self-assembled structures and to deliver DNA to cells. In this Account, we state our hypotheses and design elements as well as describe the techniques that we have utilized in our research, in order to provide readers with the tools to characterize and engineer new vectors. PMID:22439686

LaManna, Caroline M.; Lusic, Hrvoje; Camplo, Michel; McIntosh, Thomas J.; Barthélémy, Philippe; Grinstaff, Mark W.

2013-01-01

88

The Membrane and Lipids as Integral Participants in Signal Transduction: Lipid Signal Transduction for the Non-Lipid Biochemist  

ERIC Educational Resources Information Center

Reviews of signal transduction have often focused on the cascades of protein kinases and protein phosphatases and their cytoplasmic substrates that become activated in response to extracellular signals. Lipids, lipid kinases, and lipid phosphatases have not received the same amount of attention as proteins in studies of signal transduction.…

Eyster, Kathleen M.

2007-01-01

89

Lipid Trafficking in Plant Photosynthetic Cells  

Microsoft Academic Search

\\u000a Each of the various membranes in plant cells has a specific glycerolipid composition, which is kept relatively stable in different\\u000a cells and different plants. Lipid homeostasis effectors, particularly lipid transporters, remain largely uncharacterized.\\u000a Recent progresses in the field rely on the analysis of chloroplast lipid homeostasis as a model of choice. Galactolipids are\\u000a the main lipids of chloroplast membranes. Galactolipid

Juliette Jouhet; Emmanuelle Dubots; Eric Maréchal; Maryse A. Block

90

LIPID MAPS-Nature Lipidomics Gateway: An Online Resource for Students and Educators Interested in Lipids.  

PubMed

The LIPID MAPS-Nature Lipidomics Gateway is a free, comprehensive online resource providing tutorials and instructional material, experimental data for lipids and genes along with protocols and standards, databases of lipid structures and lipid-associated genes or proteins, and a variety of lipidomics tools. PMID:24764601

Sud, Manish; Fahy, Eoin; Cotter, Dawn; Dennis, Edward A; Subramaniam, Shankar

2012-01-10

91

Resveratrol in Solid Lipid Nanoparticles  

Microsoft Academic Search

This report investigates the possibility of producing solid lipid nanoparticles as protective vehicle of resveratrol, an antioxidant characterised by a fast trans-cis isomerisation. SLN aqueous dispersions were produced by hot melt homogenisation technique and characterised. It was found that the presence of tetradecyl-?-cyclodextrin in SLN formulation induced an improvement of nanoparticle characteristics. Moreover a significant reduction in resveratrol photodegradation was

Maria Eugenia Carlotti; Simona Sapino; Elena Ugazio; Marina Gallarate; Silvia Morel

2011-01-01

92

You Sank My Lipid Rafts!  

ERIC Educational Resources Information Center

The plasma membrane is the membrane that serves as a boundary between the interior of a cell and its extracellular environment. Lipid rafts are microdomains within a cellular membrane that possess decreased fluidity due to the presence of cholesterol, glycolipids, and phospholipids containing longer fatty acids. These domains are involved in many…

Campbell, Tessa N.

2009-01-01

93

Lipid membranes on nanostructured silicon.  

SciTech Connect

A unique composite nanoscale architecture that combines the self-organization and molecular dynamics of lipid membranes with a corrugated nanotextured silicon wafer was prepared and characterized with fluorescence microscopy and scanning probe microscopy. The goal of this project was to understand how such structures can be assembled for supported membrane research and how the interfacial interactions between the solid substrate and the soft, self-assembled material create unique physical and mechanical behavior through the confinement of phases in the membrane. The nanometer scale structure of the silicon wafer was produced through interference lithography followed by anisotropic wet etching. For the present study, a line pattern with 100 nm line widths, 200 nm depth and a pitch of 360 nm pitch was fabricated. Lipid membranes were successfully adsorbed on the structured silicon surface via membrane fusion techniques. The surface topology of the bilayer-Si structure was imaged using in situ tapping mode atomic force microscopy (AFM). The membrane was observed to drape over the silicon structure producing an undulated topology with amplitude of 40 nm that matched the 360 nm pitch of the silicon structure. Fluorescence recovery after photobleaching (FRAP) experiments found that on the microscale those same structures exhibit anisotropic lipid mobility that was coincident with the silicon substructure. The results showed that while the lipid membrane maintains much of its self-assembled structure in the composite architecture, the silicon substructure indeed influences the dynamics of the molecular motion within the membrane.

Slade, Andrea Lynn; Lopez, Gabriel P. (University of New Mexico, Albuquerque, NM); Ista, Linnea K. (University of New Mexico, Albuquerque, NM); O'Brien, Michael J. (University of New Mexico, Albuquerque, NM); Sasaki, Darryl Yoshio; Bisong, Paul (University of New Mexico, Albuquerque, NM); Zeineldin, Reema R. (University of New Mexico, Albuquerque, NM); Last, Julie A.; Brueck, Stephen R. J. (University of New Mexico, Albuquerque, NM)

2004-12-01

94

Lipid Nanosystems in Topical PUVA Therapy  

Microsoft Academic Search

8-methoxsalen was vehicled in nanoemulsion and in solid lipid nanoparticles (SLN) prepared by hot homogenisation technique, in order to be used in the topical psoralen UVA (PUVA) therapy. Drug entrapment efficiency in nanoparticles was improved by choosing the appropriate lipid matrix. The use of ?-tocopherol in the lipid phase reduces 8-methoxsalen induced photo-oxidation of porcine skin, which was evaluated in

Luigi Battaglia; Elena Peira; Simona Sapino; Marina Gallarate

2011-01-01

95

Original article Lipid utilization and carbohydrate partitioning  

E-print Network

Original article Lipid utilization and carbohydrate partitioning during germination of English — Conversion of reserve lipids in the seed, and carbohydrate and dry matter partitioning dur- ing in lipid content with a concomitant rise in carbohydrates (fig 2); starch appeared to be a transient sink

Paris-Sud XI, Université de

96

Lipid stability in meat and meat products  

Microsoft Academic Search

Lipid oxidation is one of the main factors limiting the quality and acceptability of meats and meat products. Oxidative damage to lipids occurs in the living animal because of an imbalance between the production of reactive oxygen species and the animal's defence mechanisms. This may be brought about by a high intake of oxidized lipids or poly-unsaturated fatty acids, or

P. A. Morrissey; P. J. A. Sheehy; K. Galvin; J. P. Kerry; D. J. Buckley

1998-01-01

97

Structure and biology of self lipid antigens.  

PubMed

Self lipid antigens induce selection and expansion of autoreactive T cells which have a role in immunoregulation and disease pathogenesis. Here we review the important biological rules which determine lipid immunogenicity. The impact of lipid structure, synthesis, traffic, membrane distribution and CD1 loading are discussed. PMID:17593657

De Libero, G; Mori, L

2007-01-01

98

Lipid domains in HIV-1 assembly  

PubMed Central

In CD+4 T cells, HIV-1 buds from the host cell plasma membrane. The viral Gag polyprotein is mainly responsible for this process. However, the intimate interaction of Gag and lipids at the plasma membrane as well as its consequences, in terms of lipids lateral organization and virus assembly, is still under debate. In this review we propose to revisit the role of plasma membrane lipids in HIV-1 Gag targeting and assembly, at the light of lipid membranes biophysics and literature dealing with Gag-lipid interactions. PMID:24904536

Yandrapalli, Naresh; Muriaux, Delphine; Favard, Cyril

2014-01-01

99

REGULATION OF LIPID DROPLETS BY AUTOPHAGY  

PubMed Central

Autophagy is a lysosomal pathway by which intracellular organelles and proteins are degraded to supply the cell with energy and maintain cellular homeostasis. Recently lipid droplets have been identified as a substrate for macroautophagy. In addition to the classic pathway of lipid metabolism by cytosolic lipases, lipid droplets are sequestered in autophagosomes that fuse with lysosomes for the breakdown of lipid droplet components by lysosomal enzymes. The ability of autophagy to respond to changes in nutrient supply allows the cell to alter lipid droplet metabolism to meet cellular energy demands. Pathophysiological changes in autophagic function can alter cellular lipid metabolism and promote disease states. Autophagy therefore represents a new cellular target for abnormalities in lipid metabolism and accumulation. PMID:21419642

Dong, Hanqing; Czaja, Mark J.

2011-01-01

100

Milk lipid secretion: recent biomolecular aspects  

PubMed Central

Neonates of most species depend on milk lipids for calories, fat-soluble vitamins, and bioactive lipid components for growth and development during the postnatal period. To meet neonatal nutrition and development needs, the mammary gland has evolved efficient mechanisms for synthesizing and secreting large quantities of lipid during lactation. Although the biochemical steps involved in milk lipid synthesis are understood, the identities of the genes mediating these steps and the molecular physiology of milk lipid production and secretion have only recently begun to be understood in detail through advances in mouse genetics, gene expression analysis, protein structural properties, and the cell biology of lipid metabolism. This review discusses emerging data about the molecular, cellular, and structural determinants of milk lipid synthesis and secretion within the context of physiological functions. PMID:24605173

McManaman, James L.

2014-01-01

101

Targeting protein lipidation in disease.  

PubMed

Fatty acids and/or isoprenoids are covalently attached to a variety of disease-related proteins. The distinct chemical properties of each of these hydrophobic moieties allow lipid modification to serve as a mechanism to regulate protein structure, localization and function. This review highlights recent progress in identifying inhibitors of protein lipidation and their effects on human disease. Myristoylation inhibitors have shown promise in blocking the action of human pathogens. Although inhibitors that block prenylation of Ras proteins have not yet been successful for cancer treatment, they may be efficacious in the rare premature aging syndrome progeria. Agents that alter the palmitoylation status of Ras, Wnt and Hh proteins have recently been discovered, and represent the next generation of potential chemotherapeutics. PMID:22342806

Resh, Marilyn D

2012-04-01

102

Targeting Protein Lipidation in Disease  

PubMed Central

Fatty acids and/or isoprenoids are covalently attached to a variety of disease-related proteins. The distinct chemical properties of each of these hydrophobic moieties allow lipid modification to serve as a mechanism to regulate protein structure, localization and function. This review highlights recent progress in identifying inhibitors of protein lipidation and their effects on human disease. Myristoylation inhibitors have shown promise in blocking the action of human pathogens. Although inhibitors that block prenylation of Ras proteins have not yet been successful for cancer treatment, they may be efficacious in the rare premature aging syndrome progeria. Agents that alter the palmitoylation status of Ras, Wnt and Hh proteins have recently been discovered, and represent the next generation of potential chemotherapeutics. PMID:22342806

Resh, Marilyn D.

2012-01-01

103

Lipid Bodies in Inflammatory Cells  

PubMed Central

Lipid bodies (LBs), also known as lipid droplets, have increasingly been recognized as functionally active organelles linked to diverse biological functions and human diseases. These organelles are actively formed in vivo within cells from the immune system, such as macrophages, neutrophils, and eosinophils, in response to different inflammatory conditions and are sites for synthesis and storage of inflammatory mediators. In this review, the authors discuss structural and functional aspects of LBs and current imaging techniques to visualize these organelles in cells engaged in inflammatory processes, including infectious diseases. The dynamic morphological aspects of LBs in leukocytes as inducible, newly formable organelles, elicitable in response to stimuli that lead to cellular activation, contribute to the evolving understanding of LBs as organelles that are critical regulators of different inflammatory diseases, key markers of leukocyte activation, and attractive targets for novel anti-inflammatory therapies. PMID:21430261

Melo, Rossana C. N.; D’Avila, Heloisa; Wan, Hsiao-Ching; Bozza, Patrícia T.; Dvorak, Ann M.; Weller, Peter F.

2011-01-01

104

[News in lipid lowering treatment].  

PubMed

Options for modification of lipoprotein metabolism and, thus, for reduction of atherothrombotic complication have widened over recent years. Apart from the development of novel approaches new pharmacological formulations of common lipid lowering drugs have been prepared- e.g. statin-containing nanoparticles, fibrate nanoparticles with a much higher bioavailability etc. Even the oldest lipid lowering agents - resins - have not been forgotten due to its once again discovered positive impact of these agents on glucose homeostasis while optimally complementing the action of statins. Clinical trials of therapies targeting HDL particle metabolism are being in progress despite we have not gathered any unambiguous evidence of positive effect of the CETP inhibitors or apoA1 mime-tics on the progression of atherosclerosis. Brand new approaches in the treatment of dyslipidemia including MTTP and PCSK9 inhibition or therapies utilizing anti-sense technologies rapidly accumulate evidence from clinical studies. We have already learned about their lipid-modifying efficacy particularly in patients with familial hypercholesterolemia, however, data from other patients´ populations can be expected quite soon. PMID:25600041

Vrablík, Michal; ?eška, Richard

2014-11-01

105

Lipid converter, a framework for lipid manipulations in molecular dynamics simulations.  

PubMed

Construction of lipid membrane and membrane protein systems for molecular dynamics simulations can be a challenging process. In addition, there are few available tools to extend existing studies by repeating simulations using other force fields and lipid compositions. To facilitate this, we introduce Lipid Converter, a modular Python framework for exchanging force fields and lipid composition in coordinate files obtained from simulations. Force fields and lipids are specified by simple text files, making it easy to introduce support for additional force fields and lipids. The converter produces simulation input files that can be used for structural relaxation of the new membranes. PMID:25081234

Larsson, Per; Kasson, Peter M

2014-11-01

106

Specificity of Intramembrane Protein–Lipid Interactions  

PubMed Central

Our concept of biological membranes has markedly changed, from the fluid mosaic model to the current model that lipids and proteins have the ability to separate into microdomains, differing in their protein and lipid compositions. Since the breakthrough in crystallizing membrane proteins, the most powerful method to define lipid-binding sites on proteins has been X-ray and electron crystallography. More recently, chemical biology approaches have been developed to analyze protein–lipid interactions. Such methods have the advantage of providing highly specific cellular probes. With the advent of novel tools to study functions of individual lipid species in membranes together with structural analysis and simulations at the atomistic resolution, a growing number of specific protein–lipid complexes are defined and their functions explored. In the present article, we discuss the various modes of intramembrane protein–lipid interactions in cellular membranes, including examples for both annular and nonannular bound lipids. Furthermore, we will discuss possible functional roles of such specific protein–lipid interactions as well as roles of lipids as chaperones in protein folding and transport. PMID:21536707

Contreras, Francesc-Xabier; Ernst, Andreas Max; Wieland, Felix; Brügger, Britta

2011-01-01

107

Lipid rafts in neurodegeneration and neuroprotection.  

PubMed

The collective properties of the lipids that form biological membranes give rise to a very high level of lateral organization within the membranes. Lipid-driven membrane organization allows the segregation of membrane-associated components into specific lipid rafts, which function as dynamic platforms for signal transduction, protein processing, and membrane turnover. A number of events essential for the functional integrity of the nervous system occur in lipid rafts and depend on lipid raft organization. Alterations of lipid composition that lead to abnormal lipid raft organization and consequent deregulation of lipid raft-dependent signaling are often associated with neurodegenerative diseases. The amyloidogenic processing of proteins involved in the pathogenesis of major nervous system diseases, including Alzheimer's disease and Parkinson's disease, requires lipid raft-dependent compartmentalization at the membrane level. Improved understanding of the forces that control lipid raft organization will facilitate the development of novel strategies for the effective prevention and treatment of neurodegenerative and age-related brain diseases. PMID:24362851

Sonnino, Sandro; Aureli, Massimo; Grassi, Sara; Mauri, Laura; Prioni, Simona; Prinetti, Alessandro

2014-08-01

108

Effect of brown seaweed lipids on fatty acid composition and lipid hydroperoxide levels of mouse liver.  

PubMed

Brown seaweed lipids from Undaria pinnatifida (Wakame), Sargassum horneri (Akamoku), and Cystoseira hakodatensis (Uganomoku) contained several bioactive compounds, namely, fucoxanthin, polyphenols, and omega-3 polyunsaturated fatty acids (PUFA). Fucoxanthin and polyphenol contents of Akamoku and Uganomoku lipids were higher than those of Wakame lipids, while Wakame lipids showed higher total omega-3 PUFA content than Akamoku and Uganomoku lipids. The levels of docosahexaenoic acid (DHA) and arachidonic acid (AA) in liver lipids of KK-A(y) mouse significantly increased by Akamoku and Uganomoku lipid feeding as compared with the control, but not by Wakame lipid feeding. Fucoxanthin has been reported to accelerate the bioconversion of omega-3 PUFA and omega-6 PUFA to DHA and AA, respectively. The higher hepatic DHA and AA level of mice fed Akamoku and Uganomoku lipids would be attributed to the higher content of fucoxanthin of Akamoku and Uganomoku lipids. The lipid hydroperoxide levels of the liver of mice fed brown seaweed lipids were significantly lower than those of control mice, even though total PUFA content was higher in the liver of mice fed brown seaweed lipids. This would be, at least in part, due to the antioxidant activity of fucoxanthin metabolites in the liver. PMID:21405010

Airanthi, M K Widjaja-Adhi; Sasaki, Naoya; Iwasaki, Sayaka; Baba, Nobuko; Abe, Masayuki; Hosokawa, Masashi; Miyashita, Kazuo

2011-04-27

109

Immunostimulatory lipid nanoparticles from herbal medicine.  

PubMed

Reproducibility is an important issue in biological characterization of drug candidates and natural products. It is not uncommon to encounter cases in which supposedly the same sample exhibits very different biological activities. During our characterization of macrophage-stimulatory lipids from herbal medicine, it was found that the potency of these lipids could vary substantially from experiment to experiment. Further analysis of this reproducibility issue led to the discovery of solvent-dependent nanoparticle formation by these lipids. While larger nanoparticles (approximately 100 nm) of these lipids showed modest macrophage-stimulatory activity, smaller nanoparticles (<10 nm) of the same lipids exhibited substantially higher potency. Thus, the study revealed an unexpected link between nanoparticle formation and macrophage-stimulatory activity of plant lipids. Although nanoparticles have been extensively studied in the context of vehicles for drug delivery, our finding indicates that drugs themselves can form nanoassemblies, and their biological properties may be altered by the way they assemble. PMID:24495243

Hasson, Tal H; Takaoka, Anna; de la Rica, Roberto; Matsui, Hiroshi; Smeureanu, Gabriela; Drain, Charles M; Kawamura, Akira

2014-04-01

110

Lipid Disturbances in Psoriasis: An Update  

PubMed Central

Psoriasis is a common disease with the population prevalence ranging from 2% to 3%. Its prevalence in the population is affected by genetic, environmental, viral, infectious, immunological, biochemical, endocrinological, and psychological factors, as well as alcohol and drug abuse. In the recent years, psoriasis has been recognised as a systemic disease associated with numerous multiorgan abnormalities and complications. Dyslipidemia is one of comorbidities in psoriatic patients. Lipid metabolism studies in psoriasis have been started at the beginning of the 20th century and are concentrated on skin surface lipids, stratum corneum lipids and epidermal phospholipids, serum lipids, dermal low-density lipoproteins in the psoriatic skin, lipid metabolism, oxidative stress and correlations between inflammatory parameters, lipid parameters and clinical symptoms of the disease. On the basis of the literature data, psoriasis can be described as an immunometabolic disease. PMID:20706605

Pietrzak, Aldona; Michalak-Stoma, Anna; Chodorowska, Gra?yna; Szepietowski, Jacek C.

2010-01-01

111

Common sense treatment for common lipid disorders.  

PubMed

Dyslipidemia is a common, major modifiable risk factor for cardiovascular disease. Screening for lipid disorders is simple, and available treatments decrease disease risk. However, secondary causes of dyslipidemia are probably underappreciated, and severe lipid elevations should be referred to a lipid specialist. Patients usually respond to lifestyle modifications and drug therapy guided by a stepwise approach supported by the results of clinical trials, but several misconceptions may interfere with treatment strategies. PMID:21568232

Johnson, Mariko; Semenkovich, Clay F

2011-01-01

112

Lipid composition of oats ( Avena sativa L.)  

Microsoft Academic Search

Compositions of lipids extracted from a sample of Hinoat oat by seven solvent systems and that extracted with chloroform\\/methanol\\u000a (2:1 v\\/v) from six selected cultivars representing high and low lipid contents are reported. Lipid components (steryl esters,\\u000a triglycerides, partial glycerides, free fatty acids, glycolipids and phospholipids) were separated by silicic acid column\\u000a chromatography and thin layer chromatography and quantitated by

M. R. Sahasrabudhe

1979-01-01

113

Identification and composition of turnip root lipids  

Microsoft Academic Search

Two varieties of turnip, Laurentian and Wye, were examined for their lipid and fatty acid composition. Lipids extracted with\\u000a 80% ethanol contained variable quantities of phosphatidic acid, which was considered to be an artifact. Crude lipids were\\u000a fractionated by TLC, and fatty acids and sterols were analyzed by GLC. Among the common phospholipids, cardiolipid and phosphatidyl\\u000a glycerol were abundant components.

Marius Lepage

1967-01-01

114

Polar lipid composition of a new halobacterium  

NASA Technical Reports Server (NTRS)

Investigations of the polar lipid composition of a new aerobic, extremely halophilic aracheabacterium capable of nitrate reduction have shown that this organism contains two previously unknown phospholycolipids derived from diphytanyl glycerol diethers. Comparison of the lipid pattern from this new isolate with other known strains indicate that this organism is novel. On the basis of the unique polar lipid pattern it can be concluded that this organism represents a new taxon, at least at the species level.

Tindall, B. J.; Tomlinson, G. A.; Hochstein, L. I.

1987-01-01

115

Lipid sac area as a proxy for individual lipid content of arctic calanoid copepods  

PubMed Central

We present an accurate, fast, simple and non-destructive photographic method to estimate wax ester and lipid content in single individuals of the calanoid copepod genus Calanus and test this method against gas-chromatographic lipid measurements. PMID:20824043

Vogedes, Daniel; Varpe, Øystein; Søreide, Janne E.; Graeve, Martin; Berge, Jørgen; Falk-Petersen, Stig

2010-01-01

116

Structural Dynamics Of The S4 Voltage-Sensor Helix In Lipid Bilayers Lacking Lipid Phosphates  

PubMed Central

Voltage-dependent K+ (Kv) channels require lipid phosphates for functioning. The S4 helix, which carries the gating charges in the voltage-sensing domain (VSD), inserts into membranes while being stabilized by a protein-lipid interface in which lipid phosphates play an essential role. To examine the physical basis of the protein-lipid interface in the absence of lipid phosphates, we performed molecular dynamics (MD) simulations of a KvAP S4 variant (S4mut) in bilayers with and without lipid phosphates. We find that in dioleoyltrimethylammoniumpropane (DOTAP) bilayers lacking lipid phosphates, the gating charges are solvated by anionic counterions and, hence, lack the bilayer support provided by phosphate-containing palmitoyloleoylglycerophosphocholine (POPC) bilayers. The result is a water-permeable bilayer with a significantly smaller deformations around the peptide. Together, these results provide an explanation for the non-functionality of VSDs in terms of a destabilizing protein-lipid interface. PMID:21692541

Andersson, Magnus; Freites, J. Alfredo; Tobias, Douglas J.; White, Stephen H.

2011-01-01

117

SEASONAL VARIABILTIY LIPIDS, LIPID CLASSES AND PCBS IN INDIGENOUS POPULATIONS OF RIBBED MUSSELS, MODIOLUS DEMISSUS  

EPA Science Inventory

Two indigenous ribbed mussel (Modiolus demissus) populations were sampled approximately every four weeks during 1997 to investigate the seasonal variability of total lipids, lipid classes, and polychlorinated biphenyl (PCB) concentrations. One population was located in a highly c...

118

Monolayer studies of insulin-lipid interactions.  

PubMed

The interactions between insulin and various lipids were studied by monolayer penetration experiments at constant surface area. The increase in surface pressure, delta II, of a lipid film depended upon the particular lipid used and the concentration of insulin in the subphase. For all lipids studied, delta II was dependent on the initial surface pressure of the lipid film. Evidence of the interaction between insulin and the lipids was found in the ability of insulin to penetrate lipid films with initial pressures greater than 16 dynes/cm, the maximum surface pressure obtained by insulin alone. For phospholipids, both the nonpolar and polar regions influenced the degree of interaction with insulin. Saturated chain lecithins exhibited less penetration than phospholipids with unsaturated hydrocarbon chains. The net charge of the lipid was not found to be an important determinant of penetration; however, the structure of the polar group can have a dramatic effect. Insulin penetration of mixed lipid films cannot be predicted by the penetration characteristics of the pure components. The possible role of these interactions in determining the geography of the insulin molecule within the liposome and its resultant effects on the stability is discussed. PMID:6341537

Schwinke, D L; Ganesan, M G; Weiner, N D

1983-03-01

119

Lipid bilayer composition influences small multidrug transporters  

PubMed Central

Background Membrane proteins are influenced by their surrounding lipids. We investigate the effect of bilayer composition on the membrane transport activity of two members of the small multidrug resistance family; the Escherichia coli transporter, EmrE and the Mycobacterium tuberculosis, TBsmr. In particular we address the influence of phosphatidylethanolamine and anionic lipids on the activity of these multidrug transporters. Phosphatidylethanolamine lipids are native to the membranes of both transporters and also alter the lateral pressure profile of a lipid bilayer. Lipid bilayer lateral pressures affect membrane protein insertion, folding and activity and have been shown to influence reconstitution, topology and activity of membrane transport proteins. Results Both EmrE and TBsmr are found to exhibit a similar dependence on lipid composition, with phosphatidylethanolamine increasing methyl viologen transport. Anionic lipids also increase transport for both EmrE and TBsmr, with the proteins showing a preference for their most prevalent native anionic lipid headgroup; phosphatidylglycerol for EmrE and phosphatidylinositol for TBsmr. Conclusion These findings show that the physical state of the membrane modifies drug transport and that substrate translocation is dependent on in vitro lipid composition. Multidrug transport activity seems to respond to alterations in the lateral forces exerted upon the transport proteins by the bilayer. PMID:19032749

Charalambous, Kalypso; Miller, David; Curnow, Paul; Booth, Paula J

2008-01-01

120

Embedding resorcinarene cavitands in lipid vesicles†  

PubMed Central

A fluorescently labeled resorcinarene cavitand has been successfully embedded in DLPC lipid vesicles and imaged using confocal microscopy. The cavitand resides exclusively in the bilayer. PMID:23144560

Feher, Katie M.; Hoang, Hai

2012-01-01

121

Polar lipid composition of mammalian hair.  

PubMed

The types and amounts of polar lipids from the hair of monkey (Macacca fascicularis), dog (Canis familiaris), pig (Sus scrofa) and porcupine (Erethizon dorsatum) have been determined by quantitative thin-layer chromatography. The polar lipid content of the hair samples ranged from 0.6 to 1.6 wt%. Lipid compositions included ceramides (57-63% of the polar lipid by weight), glycosphingolipids (7-9%) and cholesteryl sulfate (22-29%). Several minor components (4-7%) remain unidentified. The results suggest that cholesteryl sulfate may be an important determinant of the cohesiveness of hair. PMID:3581794

Wix, M A; Wertz, P W; Downing, D T

1987-01-01

122

Integral lipid in human hair follicle.  

PubMed

On the hair surface, cells are covered with a thin lipid layer (LL) covalently bonded to hair proteins. This integral hair lipid is different from sebaceus lipid. We conducted this study to examine the lipid distribution in human hair follicle. Transmission electron microscopy was performed to observe the ultrastructure of the LL. Hair follicles were cut and observed longitudinally along the hair axis. For transmission electron microscopy, new fixative (Lee's fixative: composed of OsO4 and RuO4) was designed as the conventional fixatives such as OsO4 or RuO4 alone were not appropriate for staining for hair follicle lipid. In addition, we measured the chemical composition of integral hair lipid by high-performance thin-layer chromatography. From the above experimental procedure, it was discovered that the lipid in the hair follicle was mainly distributed in hair cuticle and keratinized inner root sheath. A multitude of lamellar granule is observed in the vicinity of the above LL. The chemical composition of integral hair lipid was different from those of epidermal or sebaceous lipids. It is assumed that the LL in the hair follicle is similar to the epidermal LL playing an important role as a skin barrier in the stratum corneum. We proposed here the new terminology "hair barrier" from this point of view. PMID:16382672

Lee, Won-Soo; Oh, Tak Heon; Chun, Seung Hyun; Jeon, Soo Young; Lee, Eun Young; Lee, Sanghoon; Park, Won-Seok; Hwang, Sungjoo

2005-12-01

123

Studies of epidermal lipids using electron microscopy.  

PubMed

Ruthenium tetroxide fixation has permitted the electron microscopic visualization of intercellular lipid lamellae in thin sections of stratum corneum. This development complements prior freeze-fracture studies of lipid lamellae and has advanced our knowledge about the ultrastructure of epidermal lipids in several ways. We have demonstrated a continuous lipid envelope that surrounds each differentiated stratum corneum cell and the presence of lipid lamellae throughout the entire stratum corneum of three mammalian species, including humans. Wherever lamellae are seen, they are present in multiples of one, two, or more pairs of bilayers, consistent with their formation from fused, flattened lipid vesicles. A unique pattern of lipid monolayers intervening between each pair of bilayers, based on sharing lipid chains between bilayers, has been proposed. In regions where there are no intercellular lamellae between corneocytes, intervening monolayers are in contact with adjacent lipid envelopes that might be involved in stratum corneum cohesion. However, limitations to the ruthenium technique must be overcome before changes in lamellar patterns can be accurately attributed to, or correlated with, changes in permeability brought about by experimental procedures or in diseased states. PMID:1498019

Swartzendruber, D C

1992-06-01

124

Electrodiffusion of lipids on membrane surfaces  

NASA Astrophysics Data System (ADS)

Lateral translocation of lipids and proteins is a universal process on membrane surfaces. Local aggregation or organization of lipids and proteins can be induced when the random lateral motion is mediated by the electrostatic interactions and membrane curvature. Although the lateral diffusion rates of lipids on membranes of various compositions are measured and the electrostatic free energies of predetermined protein-membrane-lipid systems can be computed, the process of the aggregation and the evolution to the electrostatically favorable states remain largely undetermined. Here we propose an electrodiffusion model, based on the variational principle of the free energy functional, for the self-consistent lateral drift-diffusion of multiple species of charged lipids on membrane surfaces. Finite sizes of lipids are modeled to enforce the geometrical constraint of the lipid concentration on membrane surfaces. A surface finite element method is developed to appropriate the Laplace-Beltrami operators in the partial differential equations of the model. Our model properly describes the saturation of lipids on membrane surfaces, and correctly predicts that the MARCKS peptide can consistently sequester three multivalent phosphatidylinositol 4,5-bisphosphate lipids through its basic amino acid residues, regardless of a wide range of the percentage of monovalent phosphatidylserine in the membrane.

Zhou, Y. C.

2012-05-01

125

Steroidal Compounds in Commercial Parenteral Lipid Emulsions  

PubMed Central

Parenteral nutrition lipid emulsions made from various plant oils contain steroidal compounds, called phytosterols. During parenteral administration of lipid emulsions, phytosterols can reach levels in the blood that are many fold higher than during enteral administration. The elevated phytosterol levels have been associated with the development of liver dysfunction and the rare development of liver failure. There is limited information available in the literature related to phytosterol concentrations in lipid emulsions. The objective of the current study was to validate an assay for steroidal compounds found in lipid emulsions and to compare their concentrations in the most commonly used parenteral nutrition lipid emulsions: Liposyn® II, Liposyn® III, Lipofundin® MCT, Lipofundin® N, Structolipid®, Intralipid®, Ivelip® and ClinOleic®. Our data demonstrates that concentrations of the various steroidal compounds varied greatly between the eight lipid emulsions, with the olive oil-based lipid emulsion containing the lowest levels of phytosterols and cholesterol, and the highest concentration of squalene. The clinical impression of greater incidences of liver dysfunction with soybean versus MCT/LCT and olive/soy lipid emulsions may be reflective of the levels of phytosterols in these emulsions. This information may help guide future studies and clinical care of patients with lipid emulsion-associated liver dysfunction. PMID:23016123

Xu, Zhidong; Harvey, Kevin A.; Pavlina, Thomas; Dutot, Guy; Hise, Mary; Zaloga, Gary P.; Siddiqui, Rafat A.

2012-01-01

126

Lipid regulation of BK channel function  

PubMed Central

This mini-review focuses on lipid modulation of BK (MaxiK, BKCa) current by a direct interaction between lipid and the BK subunits and/or their immediate lipid environment. Direct lipid-BK protein interactions have been proposed for fatty and epoxyeicosatrienoic acids, phosphoinositides and cholesterol, evidence for such action being less clear for other lipids. BK ? (slo1) subunits are sufficient to support current perturbation by fatty and epoxyeicosatrienoic acids, glycerophospholipids and cholesterol, while distinct BK ? subunits seem necessary for current modulation by most steroids. Subunit domains or amino acids that participate in lipid action have been identified in a few cases: hslo1 Y318, cerebral artery smooth muscle (cbv1) R334,K335,K336, cbv1 seven cytosolic CRAC domains, slo1 STREX and ?1 T169,L172,L173 for docosahexaenoic acid, PIP2, cholesterol, sulfatides, and cholane steroids, respectively. Whether these protein motifs directly bind lipids or rather transmit the energy of lipid binding to other areas and trigger protein conformation change remains unresolved. The impact of direct lipid-BK interaction on physiology is briefly discussed. PMID:25202277

Dopico, Alex M.; Bukiya, Anna N.

2014-01-01

127

Roles of lipid metabolism in keloid development  

PubMed Central

Keloids are common cutaneous pathological scars that are characterised by the histological accumulation of fibroblasts, collagen fibres, and clinically significant invasive growth. Although increasing lines of research on keloids have revealed genetic and environmental factors that contribute to their formation, the etiology of these scars remains unclear. Several studies have suggested the involvement of lipid metabolism, from a nutritional point of view. However, the role that lipid metabolism plays in the pathogenesis and progression of keloids has not previously been reviewed. The progress that has been made in understanding the roles of the pro- and anti-inflammatory lipid mediators in inflammation, and how they relate to the formation and progression of keloids, is also outlined. In particular, the possible relationships between mechanotransduction and lipid metabolites in keloids are explored. Mechanotransduction is the process by which physical forces are converted into biochemical signals that are then integrated into cellular responses. It is possible that lipid rafts and caveolae provide the location of lipid signaling and interactions between these signaling pathways and mechanotransduction. Moreover, interactions between lipid signaling pathway molecules and mechanotransduction molecules have been observed. A better understanding of the lipid profile changes and the functional roles lipid metabolism plays in keloids will help to identify target molecules for the development of novel interventions that can prevent, reduce, or even reverse pathological scar formation and/or progression. PMID:23634948

2013-01-01

128

Advantages of total lipid hydrogenation prior to lipid class determination on chromarods-SIII  

Microsoft Academic Search

The changes in detector responses of lipid classes for standards and natural lipid samples after hydrogenation were investigated\\u000a with the TLC\\/FID Iatroscan system using Chromarods-SIII (Newman-Howells Associates, Ltd., Midwales, U.K.). Samples included\\u000a lipids of human plasma and erythrocytes, egg lipids, a fish oil concentrate and triacylglycerols of sea scallop, as well as\\u000a standards (mono-, di- and triacylglycerols, phosphatidylcholines, phosphatidylethanolamines, lysophosphatidylcholines,

N. C. Shantha; R. G. Ackman

1990-01-01

129

Macrophage heterogeneity and tissue lipids  

PubMed Central

Macrophages are present as resident cells in adipose tissue, and blood monocytes are recruited in increased numbers to sites of lipid accumulation in atherosclerosis, a modified form of inflammation in the arterial wall. Recent findings reported by 3 separate groups in this issue of the JCI provide evidence for distinct monocyte subsets, differential chemokine receptor usage, and phenotypic modulation of macrophages in murine models of genetic and high-fat diet–induced disease (see the related articles beginning on pages 175, 185, and 195). These studies raise prospects for selective therapeutic targets to ameliorate macrophage hyperinflammatory responses, while sparing host defense and repair mechanisms. PMID:17200712

Gordon, Siamon

2007-01-01

130

Phosphoinositides alter lipid bilayer properties.  

PubMed

Phosphatidylinositol-4,5-bisphosphate (PIP2), which constitutes ?1% of the plasma membrane phospholipid, plays a key role in membrane-delimited signaling. PIP2 regulates structurally and functionally diverse membrane proteins, including voltage- and ligand-gated ion channels, inwardly rectifying ion channels, transporters, and receptors. In some cases, the regulation is known to involve specific lipid-protein interactions, but the mechanisms by which PIP2 regulates many of its various targets remain to be fully elucidated. Because many PIP2 targets are membrane-spanning proteins, we explored whether the phosphoinositides might alter bilayer physical properties such as curvature and elasticity, which would alter the equilibrium between membrane protein conformational states-and thereby protein function. Taking advantage of the gramicidin A (gA) channels' sensitivity to changes in lipid bilayer properties, we used gA-based fluorescence quenching and single-channel assays to examine the effects of long-chain PIP2s (brain PIP2, which is predominantly 1-stearyl-2-arachidonyl-PIP2, and dioleoyl-PIP2) on bilayer properties. When premixed with dioleoyl-phosphocholine at 2 mol %, both long-chain PIP2s produced similar changes in gA channel function (bilayer properties); when applied through the aqueous solution, however, brain PIP2 was a more potent modifier than dioleoyl-PIP2. Given the widespread use of short-chain dioctanoyl-phosphoinositides, we also examined the effects of diC8-phosphoinositol (PI), PI(4,5)P2, PI(3,5)P2, PI(3,4)P2, and PI(3,4,5)P3. The diC8 phosphoinositides, except for PI(3,5)P2, altered bilayer properties with potencies that decreased with increasing head group charge. Nonphosphoinositide diC8 phospholipids generally were more potent bilayer modifiers than the polyphosphoinositides. These results show that physiological increases or decreases in plasma membrane PIP2 levels, as a result of activation of PI kinases or phosphatases, are likely to alter lipid bilayer properties, in addition to any other effects they may have. The results further show that exogenous PIP2, as well as structural analogues that differ in acyl chain length or phosphorylation state, alters lipid bilayer properties at the concentrations used in many cell physiological experiments. PMID:23712549

Rusinova, Radda; Hobart, E Ashley; Koeppe, Roger E; Andersen, Olaf S

2013-06-01

131

Phosphoinositides alter lipid bilayer properties  

PubMed Central

Phosphatidylinositol-4,5-bisphosphate (PIP2), which constitutes ?1% of the plasma membrane phospholipid, plays a key role in membrane-delimited signaling. PIP2 regulates structurally and functionally diverse membrane proteins, including voltage- and ligand-gated ion channels, inwardly rectifying ion channels, transporters, and receptors. In some cases, the regulation is known to involve specific lipid–protein interactions, but the mechanisms by which PIP2 regulates many of its various targets remain to be fully elucidated. Because many PIP2 targets are membrane-spanning proteins, we explored whether the phosphoinositides might alter bilayer physical properties such as curvature and elasticity, which would alter the equilibrium between membrane protein conformational states—and thereby protein function. Taking advantage of the gramicidin A (gA) channels’ sensitivity to changes in lipid bilayer properties, we used gA-based fluorescence quenching and single-channel assays to examine the effects of long-chain PIP2s (brain PIP2, which is predominantly 1-stearyl-2-arachidonyl-PIP2, and dioleoyl-PIP2) on bilayer properties. When premixed with dioleoyl-phosphocholine at 2 mol %, both long-chain PIP2s produced similar changes in gA channel function (bilayer properties); when applied through the aqueous solution, however, brain PIP2 was a more potent modifier than dioleoyl-PIP2. Given the widespread use of short-chain dioctanoyl-phosphoinositides, we also examined the effects of diC8-phosphoinositol (PI), PI(4,5)P2, PI(3,5)P2, PI(3,4)P2, and PI(3,4,5)P3. The diC8 phosphoinositides, except for PI(3,5)P2, altered bilayer properties with potencies that decreased with increasing head group charge. Nonphosphoinositide diC8 phospholipids generally were more potent bilayer modifiers than the polyphosphoinositides. These results show that physiological increases or decreases in plasma membrane PIP2 levels, as a result of activation of PI kinases or phosphatases, are likely to alter lipid bilayer properties, in addition to any other effects they may have. The results further show that exogenous PIP2, as well as structural analogues that differ in acyl chain length or phosphorylation state, alters lipid bilayer properties at the concentrations used in many cell physiological experiments. PMID:23712549

Hobart, E. Ashley; Koeppe, Roger E.; Andersen, Olaf S.

2013-01-01

132

Cholesterol Perturbs Lipid Bilayers Nonuniversally  

SciTech Connect

Cholesterol is well known to modulate the physical properties of biomembranes. Using modern x-ray scattering methods, we have studied the effects of cholesterol on the bending modulus K{sub C}, the thickness D{sub HH}, and the orientational order parameter S{sub xray} of lipid bilayers. We find that the effects are different for at least three classes of phospholipids characterized by different numbers of saturated hydrocarbon chains. Most strikingly, cholesterol strongly increases K{sub C} when both chains of the phospholipid are fully saturated but not at all when there are two monounsaturated chains.

Pan Jianjun; Mills, Thalia T.; Tristram-Nagle, Stephanie; Nagle, John F. [Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

2008-05-16

133

Interactions in lipid stabilised foam films.  

PubMed

The interaction between lipid bilayers in water has been intensively studied over the last decades. Osmotic stress was applied to evaluate the forces between two approaching lipid bilayers in aqueous solution. The force-distance relation between lipid mono- or bilayers deposited on mica sheets using a surface force apparatus (SFA) was also measured. Lipid stabilised foam films offer another possibility to study the interactions between lipid monolayers. These films can be prepared comparatively easy with very good reproducibility. Foam films consist usually of two adsorbed surfactant monolayers separated by a layer of the aqueous solution from which the film is created. Their thickness can be conveniently measured using microinterferometric techniques. Studies with foam films deliver valuable information on the interactions between lipid membranes and especially their stability and permeability. Presenting inverse black lipid membrane (BLM) foam films supply information about the properties of the lipid self-organisation in bilayers. The present paper summarises results on microscopic lipid stabilised foam films by measuring their thickness and contact angle. Most of the presented results concern foam films prepared from dispersions of the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) and some of its mixtures with the anionic lipid - 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG). The strength of the long range and short range forces between the lipid layers is discussed. The van der Waals attractive force is calculated. The electrostatic repulsive force is estimated from experiments at different electrolyte concentrations (NaCl, CaCl2) or by modification of the electrostatic double layer surface potential by incorporating charged lipids in the lipid monolayers. The short range interactions are studied and modified by using small carbohydrates (fructose and sucrose), ethanol (EtOH) or dimethylsulfoxide (DMSO). Some results are compared with the structure of lipid monolayers deposited at the liquid/air interface (monolayers spread in Langmuir trough), which are one of most studied biomembrane model system. The comparison between the film thickness and the free energy of film formation is used to estimate the contribution of the different components of the disjoining pressure to the total interaction in the film and their dependence on the composition of the film forming solution. PMID:24641908

Toca-Herrera, José Luis; Krasteva, Nadejda; Müller, Hans-Joachim; Krastev, Rumen

2014-05-01

134

Efficient conversion of biomass into lipids by using the simultaneous saccharification and enhanced lipid production process  

PubMed Central

Background Microbial lipid production by using lignocellulosic biomass as the feedstock holds a great promise for biodiesel production and biorefinery. This usually involves hydrolysis of biomass into sugar-rich hydrolysates, which are then used by oleaginous microorganisms as the carbon and energy sources to produce lipids. However, the costs of microbial lipids remain prohibitively high for commercialization. More efficient and integrated processes are pivotal for better techno-economics of microbial lipid technology. Results Here we describe the simultaneous saccharification and enhanced lipid production (SSELP) process that is highly advantageous in terms of converting cellulosic materials into lipids, as it integrates cellulose biomass hydrolysis and lipid biosynthesis. Specifically, Cryptococcus curvatus cells prepared in a nutrient-rich medium were inoculated at high dosage for lipid production in biomass suspension in the presence of hydrolytic enzymes without auxiliary nutrients. When cellulose was loaded at 32.3 g/L, cellulose conversion, cell mass, lipid content and lipid coefficient reached 98.5%, 12.4 g/L, 59.9% and 204 mg/g, respectively. Lipid yields of the SSELP process were higher than those obtained by using the conventional process where cellulose was hydrolyzed separately. When ionic liquid pretreated corn stover was used, both cellulose and hemicellulose were consumed simultaneously. No xylose was accumulated over time, indicating that glucose effect was circumvented. The lipid yield reached 112 mg/g regenerated corn stover. This process could be performed without sterilization because of the absence of auxiliary nutrients for bacterial contamination. Conclusions The SSELP process facilitates direct conversion of both cellulose and hemicellulose of lignocellulosic materials into microbial lipids. It greatly reduces time and capital costs while improves lipid coefficient. Optimization of the SSELP process at different levels should further improve the efficiency of microbial lipid technology, which in turn, promote the biotechnological production of fatty acid-derived products from lignocellulosic biomass. PMID:23497564

2013-01-01

135

Original article Light-induced protein and lipid oxidation  

E-print Network

of protein (dityrosine and dimethyl disulphide (DMDS)) and lipid (lipid hydroperoxides, pentanal, hexanal)) et des lipides (hydroperoxydes, pentanal, hexanal, heptanal) étaient significativement réduites dans

Paris-Sud XI, Université de

136

21 CFR 862.1470 - Lipid (total) test system.  

Code of Federal Regulations, 2013 CFR

...is a device intended to measure total lipids (fats or fat-like substances) in serum and plasma. Lipid (total) measurements are used in...treatment of various diseases involving lipid metabolism and atherosclerosis. (b)...

2013-04-01

137

21 CFR 862.1470 - Lipid (total) test system.  

Code of Federal Regulations, 2012 CFR

...is a device intended to measure total lipids (fats or fat-like substances) in serum and plasma. Lipid (total) measurements are used in...treatment of various diseases involving lipid metabolism and atherosclerosis. (b)...

2012-04-01

138

Method of fabricating lipid bilayer membranes on solid supports  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

139

Genetics Home Reference: Neutral lipid storage disease with myopathy  

MedlinePLUS

... Recent literature OMIM Genetic disorder catalog Conditions > Neutral lipid storage disease with myopathy On this page: Description ... Glossary definitions Reviewed February 2014 What is neutral lipid storage disease with myopathy? Neutral lipid storage disease ...

140

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

SciTech Connect

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. The 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.

Christopher Benning

2011-02-04

141

Multichannel taste sensors with lipid, lipid like polymer membranes  

NASA Astrophysics Data System (ADS)

The elaboration of a sensitive taste sensor for discrimination of different soft drinks is very important in food industry. The short review of taste sensors described in the literature is presented. Two types of potentiometric taste sensors, one with lipophilic compound-polymer membranes (ISE) and the other with lipid polymer membrane and a conducting polymer film (All solid state electrode, ASSE) were tested in appropriate taste solutions. Five channel ISE sensor was examined in acid, sour and sweet solutions. This sensor was sensitive to bitter and sour substances and not too sensitive to sucrose concentration. It was successfully used for discrimination of different kind of soft drinks. Four channel ASSE sensor was examined in sour solutions. It was found that stability and sensitivity of ASSE are lower than ISE. Therefore, it seems that the previous one cannot be applied in taste sensor.

Szpakowska, M.; Szwacki, J.; Marja?ska, E.

2008-08-01

142

Imaging lipid droplets in Arabidopsis mutants  

Technology Transfer Automated Retrieval System (TEKTRAN)

Confocal fluorescence microscopy was adapted for the imaging of neutral lipids in plant leaves with defects in normal lipid metabolism using two different fluorescent dyes. Disruptions in a gene locus, At4g24160, yielded Arabidopsis thaliana plants with a preponderance of oil bodies in their leaves ...

143

Cell Metabolism Postprandial Hepatic Lipid Metabolism  

E-print Network

Cell Metabolism Article Postprandial Hepatic Lipid Metabolism Requires Signaling through Akt2 in the absence of Akt2. These data show that insulin signaling through Akt2 promotes anabolic lipid metabolism. Sabatini,2,3,4,5 and Morris J. Birnbaum1,* 1The Institute of Diabetes, Obesity, and Metabolism, University

Sabatini, David M.

144

Plant Lipids: Metabolism, Mutants, and Membranes  

Microsoft Academic Search

The mechanisms that regulate plant lipid metabolism determine the dietary and industrial value of storage oils found in economically important species and may control the ability of many plants to survive exposure to temperature extremes. Many of the problems researchers have in defining the pathways, enzymes, and genes involved in plant lipid metabolism appear to be amenable to analysis by

Chris Somerville; John Browse

1991-01-01

145

Do lipids influence the allergic sensitization process?  

PubMed

Allergic sensitization is a multifactorial process that is not only influenced by the allergen and its biological function per se but also by other small molecular compounds, such as lipids, that are directly bound as ligands by the allergen or are present in the allergen source. Several members of major allergen families bind lipid ligands through hydrophobic cavities or electrostatic or hydrophobic interactions. These allergens include certain seed storage proteins, Bet v 1-like and nonspecific lipid transfer proteins from pollens and fruits, certain inhalant allergens from house dust mites and cockroaches, and lipocalins. Lipids from the pollen coat and furry animals and the so-called pollen-associated lipid mediators are codelivered with the allergens and can modulate the immune responses of predisposed subjects by interacting with the innate immune system and invariant natural killer T cells. In addition, lipids originating from bacterial members of the pollen microbiome contribute to the outcome of the sensitization process. Dietary lipids act as adjuvants and might skew the immune response toward a TH2-dominated phenotype. In addition, the association with lipids protects food allergens from gastrointestinal degradation and facilitates their uptake by intestinal cells. These findings will have a major influence on how allergic sensitization will be viewed and studied in the future. PMID:24880633

Bublin, Merima; Eiwegger, Thomas; Breiteneder, Heimo

2014-09-01

146

Do lipids influence the allergic sensitization process?  

PubMed Central

Allergic sensitization is a multifactorial process that is not only influenced by the allergen and its biological function per se but also by other small molecular compounds, such as lipids, that are directly bound as ligands by the allergen or are present in the allergen source. Several members of major allergen families bind lipid ligands through hydrophobic cavities or electrostatic or hydrophobic interactions. These allergens include certain seed storage proteins, Bet v 1–like and nonspecific lipid transfer proteins from pollens and fruits, certain inhalant allergens from house dust mites and cockroaches, and lipocalins. Lipids from the pollen coat and furry animals and the so-called pollen-associated lipid mediators are codelivered with the allergens and can modulate the immune responses of predisposed subjects by interacting with the innate immune system and invariant natural killer T cells. In addition, lipids originating from bacterial members of the pollen microbiome contribute to the outcome of the sensitization process. Dietary lipids act as adjuvants and might skew the immune response toward a TH2-dominated phenotype. In addition, the association with lipids protects food allergens from gastrointestinal degradation and facilitates their uptake by intestinal cells. These findings will have a major influence on how allergic sensitization will be viewed and studied in the future. PMID:24880633

Bublin, Merima; Eiwegger, Thomas; Breiteneder, Heimo

2014-01-01

147

Lipid extraction from isolated single nerve cells  

NASA Technical Reports Server (NTRS)

A method of extracting lipids from single neurons isolated from lyophilized tissue is described. The method permits the simultaneous extraction of lipids from 30-40 nerve cells and for each cell provides equal conditions of solvent removal at the conclusion of extraction.

Krasnov, I. V.

1977-01-01

148

Treatment of lipid disorders after stroke.  

PubMed

The efficacy of lipid disorder therapy for the primary and secondary prevention of coronary heart disease is established. There are, however, no completed studies specifically directed at reducing the risk of stroke with lipid therapy. Although observational cohort studies have failed to demonstrate an association between lipid disorders and stroke incidence, recently completed trials of subjects at risk for coronary heart disease have shown that statins and fibric acid derivatives reduce not only the risk of myocardial infarction and death, but also that of brain infarction and transient ischemic attacks. Lipid drugs are well tolerated and treatment complications are relatively low. It seems prudent to conclude that the stroke patient with an undesirable lipid profile who has a history of coronary heart disease should receive specific treatment for the lipid disorder. Recommendations are more problematic for stroke patients with lipid disorders but no history of coronary heart disease; most should receive therapy for primary prevention of heart disease. Lipid treatment trials focused on stroke risk reduction are urgently needed. PMID:12052282

Gomes, Joao A; Robins, Sander J; Babikian, Viken L

2002-07-01

149

Lipid rafts: contentious only from simplistic standpoints  

Microsoft Academic Search

The hypothesis that lipid rafts exist in plasma membranes and have crucial biological functions remains controversial. The lateral heterogeneity of proteins in the plasma membrane is undisputed, but the contribution of cholesterol-dependent lipid assemblies to this complex, non-random organization promotes vigorous debate. In the light of recent studies with model membranes, computational modelling and innovative cell biology, I propose an

John F. Hancock

2006-01-01

150

Biosynthesis of archaeal membrane ether lipids  

PubMed Central

A vital function of the cell membrane in all living organism is to maintain the membrane permeability barrier and fluidity. The composition of the phospholipid bilayer is distinct in archaea when compared to bacteria and eukarya. In archaea, isoprenoid hydrocarbon side chains are linked via an ether bond to the sn-glycerol-1-phosphate backbone. In bacteria and eukarya on the other hand, fatty acid side chains are linked via an ester bond to the sn-glycerol-3-phosphate backbone. The polar head groups are globally shared in the three domains of life. The unique membrane lipids of archaea have been implicated not only in the survival and adaptation of the organisms to extreme environments but also to form the basis of the membrane composition of the last universal common ancestor (LUCA). In nature, a diverse range of archaeal lipids is found, the most common are the diether (or archaeol) and the tetraether (or caldarchaeol) lipids that form a monolayer. Variations in chain length, cyclization and other modifications lead to diversification of these lipids. The biosynthesis of these lipids is not yet well understood however progress in the last decade has led to a comprehensive understanding of the biosynthesis of archaeol. This review describes the current knowledge of the biosynthetic pathway of archaeal ether lipids; insights on the stability and robustness of archaeal lipid membranes; and evolutionary aspects of the lipid divide and the LUCA. It examines recent advances made in the field of pathway reconstruction in bacteria. PMID:25505460

Jain, Samta; Caforio, Antonella; Driessen, Arnold J. M.

2014-01-01

151

Altered renal lipid metabolism and renal lipid accumulation in human diabetic nephropathy.  

PubMed

Animal models link ectopic lipid accumulation to renal dysfunction, but whether this process occurs in the human kidney is uncertain. To this end, we investigated whether altered renal TG and cholesterol metabolism results in lipid accumulation in human diabetic nephropathy (DN). Lipid staining and the expression of lipid metabolism genes were studied in kidney biopsies of patients with diagnosed DN (n = 34), and compared with normal kidneys (n = 12). We observed heavy lipid deposition and increased intracellular lipid droplets. Lipid deposition was associated with dysregulation of lipid metabolism genes. Fatty acid ?-oxidation pathways including PPAR-?, carnitine palmitoyltransferase 1, acyl-CoA oxidase, and L-FABP were downregulated. Downregulation of renal lipoprotein lipase, which hydrolyzes circulating TGs, was associated with increased expression of angiopoietin-like protein 4. Cholesterol uptake receptor expression, including LDL receptors, oxidized LDL receptors, and acetylated LDL receptors, was significantly increased, while there was downregulation of genes effecting cholesterol efflux, including ABCA1, ABCG1, and apoE. There was a highly significant correlation between glomerular filtration rate, inflammation, and lipid metabolism genes, supporting a possible role of abnormal lipid metabolism in the pathogenesis of DN. These data suggest that renal lipid metabolism may serve as a target for specific therapies aimed at slowing the progression of glomerulosclerosis. PMID:24371263

Herman-Edelstein, Michal; Scherzer, Pnina; Tobar, Ana; Levi, Moshe; Gafter, Uzi

2014-03-01

152

Lxr-driven enterocyte lipid droplet formation delays transport of ingested lipids.  

PubMed

Liver X receptors (Lxrs) are master regulators of cholesterol catabolism, driving the elimination of cholesterol from the periphery to the lumen of the intestine. Development of pharmacological agents to activate Lxrs has been hindered by synthetic Lxr agonists' induction of hepatic lipogenesis and hypertriglyceridemia. Elucidating the function of Lxrs in regulating enterocyte lipid handling might identify novel aspects of lipid metabolism that are pharmacologically amenable. We took a genetic approach centered on the single Lxr gene nr1h3 in zebrafish to study the role of Lxr in enterocyte lipid metabolism. Loss of nr1h3 function causes anticipated gene regulatory changes and cholesterol intolerance, collectively reflecting high evolutionary conservation of zebrafish Lxra function. Intestinal nr1h3 activation delays transport of absorbed neutral lipids, with accumulation of neutral lipids in enterocyte cytoplasmic droplets. This delay in transport of ingested neutral lipids protects animals from hypercholesterolemia and hepatic steatosis induced by a high-fat diet. On a gene regulatory level, Lxra induces expression of acsl3a, which encodes acyl-CoA synthetase long-chain family member 3a, a lipid droplet-anchored protein that directs fatty acyl chains into lipids. Forced overexpression of acls3a in enterocytes delays, in part, the appearance of neutral lipids in the vasculature of zebrafish larvae. Activation of Lxr in the intestine cell-autonomously regulates the rate of delivery of absorbed lipids by inducting a temporary lipid intestinal droplet storage depot. PMID:25030662

Cruz-Garcia, Lourdes; Schlegel, Amnon

2014-09-01

153

Small GTPase Rab40c Associates with Lipid Droplets and Modulates the Biogenesis of Lipid Droplets  

PubMed Central

The subcellular location and cell biological function of small GTPase Rab40c in mammalian cells have not been investigated in detail. In this study, we demonstrated that the exogenously expressed GFP-Rab40c associates with lipid droplets marked by neutral lipid specific dye Oil red or Nile red, but not with the Golgi or endosomal markers. Further examination demonstrated that Rab40c is also associated with ERGIC-53 containing structures, especially under the serum starvation condition. Rab40c is increasingly recruited to the surface of lipid droplets during lipid droplets formation and maturation in HepG2 cells. Rab40c knockdown moderately decreases the size of lipid droplets, suggesting that Rab40c is involved in the biogenesis of lipid droplets. Stimulation for adipocyte differentiation increases the expression of Rab40c in 3T3-L1 cells. Rab40c interacts with TIP47, and is appositionally associated with TIP47-labeled lipid droplets. In addition, over-expression of Rab40c causes the clustering of lipid droplets independent of its GTPase activity, but completely dependent of the intact SOCS box domain of Rab40c. In addition, Rab40c displayed self-interaction as well as interaction with TIP47 and the SOCS box is essential for its ability to induce clustering of lipid droplets. Our results suggest that Rab40c is a novel Rab protein associated with lipid droplets, and is likely involved in modulating the biogenesis of lipid droplets. PMID:23638186

Tan, Ran; Wang, Weijie; Wang, Shicong; Wang, Zhen; Sun, Lixiang; He, Wei; Fan, Rong; Zhou, Yunhe; Xu, Xiaohui; Hong, Wanjin; Wang, Tuanlao

2013-01-01

154

Residual lipids of hexane-extracted repaseed meal  

Microsoft Academic Search

The residual lipids of rapeseed meals produced by pilot-scale and commercial solvent-extraction processes were extracted with\\u000a hexane (free lipids), then extracted with chloroform-methanol (bound lipids). Thin layer chromatography showed that the free\\u000a lipids were similar to those previously reported for intact mature seed. The amount of residual free lipid varied with the\\u000a method of meal production. Bound lipids were similar

M. E. Mckillican; J. A. G. Larose

1970-01-01

155

The Sec14 superfamily and mechanisms for crosstalk between lipid metabolism and lipid signaling.  

PubMed

Lipid signaling pathways define central mechanisms for cellular regulation. Productive lipid signaling requires an orchestrated coupling between lipid metabolism, lipid organization and the action of protein machines that execute appropriate downstream reactions. Using membrane trafficking control as primary context, we explore the idea that the Sec14-protein superfamily defines a set of modules engineered for the sensing of specific aspects of lipid metabolism and subsequent transduction of 'sensing' information to a phosphoinositide-driven 'execution phase'. In this manner, the Sec14 superfamily connects diverse territories of the lipid metabolome with phosphoinositide signaling in a productive 'crosstalk' between these two systems. Mechanisms of crosstalk, by which non-enzymatic proteins integrate metabolic cues with the action of interfacial enzymes, represent unappreciated regulatory themes in lipid signaling. PMID:19926291

Bankaitis, Vytas A; Mousley, Carl J; Schaaf, Gabriel

2010-03-01

156

Lipid-transfer proteins in biosynthetic pathways.  

PubMed

Compartmentalization is a defining feature of eukaryotic cells that allows the spatial segregation of different functions, such as protein and lipid synthesis, and ensures their fidelity and efficiency. This imposes the need for an intense flux of metabolic intermediates between segregated enzymatic activities, as seen for the sequential transport of neosynthesized proteins through the segments of the secretory pathway during their post-translational modification. For lipid synthesis, the identification of proteins that transfer lipids between membranes has revealed an additional mechanism for this intercompartment exchange. The intense interest elicited by the lipid-transfer proteins over the last few years has led to the definition of their central role in key processes, such as lipid metabolism, membrane trafficking, and signaling. PMID:18490149

D'Angelo, Giovanni; Vicinanza, Mariella; De Matteis, Maria Antonietta

2008-08-01

157

Diffusion in low-dimensional lipid membranes.  

PubMed

The diffusion behavior of biological components in cellular membranes is vital to the function of cells. By collapsing the complexity of planar 2D membranes down to one dimension, fundamental investigations of bimolecular behavior become possible in one dimension. Here we develop lipid nanolithography methods to produce membranes, under fluid, with widths as low as 6 nm but extending to microns in length. We find reduced lipid mobility, as the width is reduced below 50 nm, suggesting different lipid packing in the vicinity of boundaries. The insertion of a membrane protein, M2, into these systems, allowed characterization of protein diffusion using high-speed AFM to demonstrate the first membrane protein 1D random walk. These quasi-1D lipid bilayers are ideal for testing and understanding fundamental concepts about the roles of dimensionality and size on physical properties of membranes from energy transfer to lipid packing. PMID:25166509

Heath, George R; Roth, Johannes; Connell, Simon D; Evans, Stephen D

2014-10-01

158

Lipid rafts, cholesterol, and the brain  

PubMed Central

Summary Lipid rafts are specialized membrane microdomains that serve as organizing centers for assembly of signaling molecules, influence membrane fluidity and trafficking of membrane proteins, and regulate different cellular processes such as neurotransmission and receptor trafficking. In this article, we provide an overview of current methods for studying lipid rafts and models for how lipid rafts might form and function. Next, we propose a potential mechanism for regulating lipid rafts in the brain via local control of cholesterol biosynthesis by neurotrophins and their receptors. Finally, we discuss evidence that altered cholesterol metabolism and/or lipid rafts play a critical role in the pathophysiology of multiple CNS disorders, including Smith-Lemli-Opitz syndrome, Huntington, Alzheimer's, and Niemman-Pick Type C diseases. PMID:18402986

Korade, Zeljka; Kenworthy, Anne K.

2008-01-01

159

Skin lipids from Saudi Arabian birds  

PubMed Central

Skin lipids play an important role in the regulation of cutaneous water loss (CWL). Earlier studies have shown that Saudi desert birds exhibit a tendency of reduced CWL than birds from temperate environment due to adaptive changes in composition of their skin lipids. In this study, we used thin-layer chromatography (TLC) for separation and detection of non-polar and polar lipids from the skin of six bird species including sooty gull, brown booby, house sparrow, Arabian waxbill, sand partridge, and laughing dove. The lipids were separated and detected on Silica gel G coated TLC plates and quantified by using densitometric image analysis. Rf values of the non-polar lipids were as follows: cholesterol (0.29), free fatty acids (0.58), triacylglycerol (0.69), fatty acids methyl esters (0.84) and cholesterol ester (0.97). Rf values for the polar lipids were: cerebroside (0.42), ceramide (0.55) and cholesterol (0.73). The results showed the abundance of fatty acids methyl esters (47.75–60.46%) followed by triacylglycerol (12.69–24.14%). The remaining lipid compositions were as follows: cholesterol (4.09–13.18%), ceramide (2.18–13.27%), and cerebroside (2.53–12.81%). In conclusion, our findings showed that TLC is a simple and sensitive method for the separation and quantification of skin lipids. We also reported a new protocol for lipid extraction using the zirconia beads for efficient disruption of skin tissues. This study will help us better understand the role of skin lipids in adaptive physiology towards adverse climatic conditions. PMID:24600311

Khan, Haseeb A.; Arif, Ibrahim A.; Williams, Joseph B.; Champagne, Alex M.; Shobrak, Mohammad

2013-01-01

160

Skin lipids from Saudi Arabian birds.  

PubMed

Skin lipids play an important role in the regulation of cutaneous water loss (CWL). Earlier studies have shown that Saudi desert birds exhibit a tendency of reduced CWL than birds from temperate environment due to adaptive changes in composition of their skin lipids. In this study, we used thin-layer chromatography (TLC) for separation and detection of non-polar and polar lipids from the skin of six bird species including sooty gull, brown booby, house sparrow, Arabian waxbill, sand partridge, and laughing dove. The lipids were separated and detected on Silica gel G coated TLC plates and quantified by using densitometric image analysis. Rf values of the non-polar lipids were as follows: cholesterol (0.29), free fatty acids (0.58), triacylglycerol (0.69), fatty acids methyl esters (0.84) and cholesterol ester (0.97). Rf values for the polar lipids were: cerebroside (0.42), ceramide (0.55) and cholesterol (0.73). The results showed the abundance of fatty acids methyl esters (47.75-60.46%) followed by triacylglycerol (12.69-24.14%). The remaining lipid compositions were as follows: cholesterol (4.09-13.18%), ceramide (2.18-13.27%), and cerebroside (2.53-12.81%). In conclusion, our findings showed that TLC is a simple and sensitive method for the separation and quantification of skin lipids. We also reported a new protocol for lipid extraction using the zirconia beads for efficient disruption of skin tissues. This study will help us better understand the role of skin lipids in adaptive physiology towards adverse climatic conditions. PMID:24600311

Khan, Haseeb A; Arif, Ibrahim A; Williams, Joseph B; Champagne, Alex M; Shobrak, Mohammad

2014-04-01

161

Structure determination of lipid bilayers.  

PubMed Central

A method of determining the phases of X-ray reflections from oriented model membrane systems at low resolution is described. The method involves deconvolution and requires that d less than or equal to 2v where v is the width of the head group region within the bilayer and d is the thickness of the bilayer. The method can be used with a single set of X-ray data and applies to lipid bilayers which have a relatively constant density in the hydrocarbon region. Phases for the first five or six orders of phosphatidylethanolamine and lecithin are derived. A refined analysis based upon deconvolution but using information inherent in the Fourier profile is also described. PMID:698345

Worthington, C R; Kharf, R S

1978-01-01

162

Lipid body biogenesis and the role of microtubules in lipid synthesis in Ornithogalum umbellatum lipotubuloids.  

PubMed

Lipid bodies present in lipotubuloids of Ornithogalum umbellatum ovary epidermis take the form of a lens between leaflets of ER (endoplasmic reticulum) membrane filled with a highly osmiophilic substance. The two enzymes, DGAT1 [DAG (diacylglycerol) acyltransferase 1] and DGAT2 (DAG acyltransferase 2), involved in this process are synthesized on rough ER and localized in the ER near a monolayer surrounding entities like lipid bodies. After reaching the appropriate size, newly formed lipid bodies transform into mature spherical lipid bodies filled with less osmiophilic content. They appear to be surrounded by a half-unit membrane, with numerous microtubules running adjacently in different directions. The ER, no longer continuous with lipid bodies, makes contact with them through microtubules. At this stage, lipid synthesis takes place at the periphery of lipid bodies. This presumption, and a hypothesis that microtubules are involved in lipid synthesis delivering necessary components to lipid bodies, is based on strong arguments: (i) silver grains first appear over microtubules after a short [3H]palmitic acid incubation and before they are observed over lipid bodies; (ii) blockade of [3H]palmitic acid incorporation into lipotubuloids by propyzamide, an inhibitor of microtubule function; and (iii) the presence of gold grains above the microtubules after DGAT1 and DGAT2 reactions, as also near microtubules after an immunogold method that identifies phospholipase D1. PMID:22295975

Kwiatkowska, Maria; Pop?o?ska, Katarzyna; Wojtczak, Agnieszka; St?pi?ski, Dariusz; Polit, Justyna Teresa

2012-05-01

163

Molecular sorting of lipids by bacteriorhodopsin in dilauroylphosphatidylcholine/distearoylphosphatidylcholine lipid bilayers.  

PubMed Central

A combined experimental and theoretical study is performed on binary dilauroylphosphatidylcholine/distearoylphosphatidylcholine (DLPC/DSPC) lipid bilayer membranes incorporating bacteriorhodopsin (BR). The system is designed to investigate the possibility that BR, via a hydrophobic matching principle related to the difference in lipid bilayer hydrophobic thickness and protein hydrophobic length, can perform molecular sorting of the lipids at the lipid-protein interface, leading to lipid specificity/selectivity that is controlled solely by physical factors. The study takes advantage of the strongly nonideal mixing behavior of the DLPC/DSPC mixture and the fact that the average lipid acyl-chain length is strongly dependent on temperature, particularly in the main phase transition region. The experiments are based on fluorescence energy transfer techniques using specifically designed lipid analogs that can probe the lipid-protein interface. The theoretical calculations exploit a microscopic molecular interaction model that embodies the hydrophobic matching as a key parameter. At low temperatures, in the gel-gel coexistence region, experimental and theoretical data consistently indicate that BR is associated with the short-chain lipid DLPC. At moderate temperatures, in the fluid-gel coexistence region, BR remains in the fluid phase, which is mainly composed of short-chain lipid DLPC, but is enriched at the interface between the fluid and gel domains. At high temperatures, in the fluid phase, BR stays in the mixed lipid phase, and the theoretical data suggest a preference of the protein for the long-chain DSPC molecules at the expense of the short-chain DLPC molecules. The combined results of the experiments and the calculations provide evidence that a molecular sorting principle is active because of hydrophobic matching and that BR exhibits physical lipid selectivity. The results are discussed in the general context of membrane organization and compartmentalization and in terms of nanometer-scale lipid-domain formation. Images FIGURE 1 PMID:9336190

Dumas, F; Sperotto, M M; Lebrun, M C; Tocanne, J F; Mouritsen, O G

1997-01-01

164

Lipid nanoscaffolds in carbon nanotube arrays  

NASA Astrophysics Data System (ADS)

We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields.We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields. Electronic supplementary information (ESI) available: Additional wide angle X-ray scattering (WAXS) data on the alignment of lipid nanostructures, control and time resolved 2-d images of egg ovalbumin encapsulation and a summary picture of the present work. See DOI: 10.1039/c3nr02068a

Paukner, Catharina; Koziol, Krzysztof K. K.; Kulkarni, Chandrashekhar V.

2013-09-01

165

Lipid metabolism and toxicity in the heart.  

PubMed

The heart has both the greatest caloric needs and the most robust oxidation of fatty acids (FAs). Under pathological conditions such as obesity and type 2 diabetes, cardiac uptake and oxidation are not balanced and hearts accumulate lipid potentially leading to cardiac lipotoxicity. We will first review the pathways utilized by the heart to acquire FAs from the circulation and to store triglyceride intracellularly. Then we will describe mouse models in which excess lipid accumulation causes heart dysfunction and experiments performed to alleviate this toxicity. Finally, the known relationships between heart lipid metabolism and dysfunction in humans will be summarized. PMID:22682221

Goldberg, Ira J; Trent, Chad M; Schulze, P Christian

2012-06-01

166

Achieving lipid targets in primary care settings.  

PubMed

Achieving low-density lipoprotein cholesterol (LDL-C) goals in clinical practice is still unsatisfactory. Furthermore, a significant residual risk remains, even after reaching LDL-C targets, in terms of both fasting and postprandial triglycerides, high-density lipoprotein cholesterol (quantity and quality) and small dense LDL particles. Statins are the first choice for treating lipid abnormalities. Other lipid-lowering agents can be administered when statins are not tolerated and if LDL-C targets are not reached. Furthermore, multifactorial treatment, including a statin, exerts several beneficial effects on cardiovascular and residual risk reduction. The role of novel developing lipid therapies in clinical practice remains to be established. PMID:25007308

Katsiki, Niki; Athyros, Vasilios G; Karagiannis, Asterios

2014-10-01

167

High-throughput formation of lipid bilayer membrane arrays with an asymmetric lipid composition  

PubMed Central

We present a micro-device in which more than 10,000 asymmetric lipid bilayer membranes are formed at a time on micro-chamber arrays. The arrayed asymmetric lipid bilayers, where lipid compositions are different between the inner and outer leaflets, are formed with high efficiency of over 97% by injecting several types of liquids into a micro-device that has hydrophilic-in-hydrophobic surfaces. The lipid compositional asymmetry is an intrinsic property of bio-membranes, and therefore, this micro-device extends the versatility of artificial lipid-bilayer systems, which were previously limited to symmetric bilayer formation, and could contribute to the understanding of the role of lipid compositional asymmetry in cell physiology and also to further analytical and pharmacological applications. PMID:25399694

Watanabe, Rikiya; Soga, Naoki; Yamanaka, Tomoko; Noji, Hiroyuki

2014-01-01

168

Update of the LIPID MAPS comprehensive classification system for lipids1  

PubMed Central

In 2005, the International Lipid Classification and Nomenclature Committee under the sponsorship of the LIPID MAPS Consortium developed and established a “Comprehensive Classification System for Lipids” based on well-defined chemical and biochemical principles and using an ontology that is extensible, flexible, and scalable. This classification system, which is compatible with contemporary databasing and informatics needs, has now been accepted internationally and widely adopted. In response to considerable attention and requests from lipid researchers from around the globe and in a variety of fields, the comprehensive classification system has undergone significant revisions over the last few years to more fully represent lipid structures from a wider variety of sources and to provide additional levels of detail as necessary. The details of this classification system are reviewed and updated and are presented here, along with revisions to its suggested nomenclature and structure-drawing recommendations for lipids. PMID:19098281

Fahy, Eoin; Subramaniam, Shankar; Murphy, Robert C.; Nishijima, Masahiro; Raetz, Christian R. H.; Shimizu, Takao; Spener, Friedrich; van Meer, Gerrit; Wakelam, Michael J. O.; Dennis, Edward A.

2009-01-01

169

Lipid metabolism of Agaricus bisporus (Lange) sing.: I. Analysis of sporophore and mycelial lipids  

Microsoft Academic Search

The lipid components of four strains ofAgricus bisporus (Lange) Sing., the cultivated mushroom, were analyzed. Both sporophore and mycelial samples were obtained from beds in normal\\u000a production. A method for obtaining mycelium free of compost was developed. Neutral lipids were separated from polar lipids\\u000a by silicic acid column chromatography. Each fraction was separated by thin layer chromatography. Fatty acid methyl

R. Barry Holtz; Lee C. Schisler

1971-01-01

170

STKE Focus Issue on Lipid Biology: Lipids, Partners in Cellular Signaling  

NSDL National Science Digital Library

This week's issue of Science features a special section called Lipid Biology (http://stke.sciencemag.org/cgi/content/summary/vj_sci;294/5548/1861) that highlights some of the complex and intriguing roles of lipids in numerous processes, including cellular lipid homeostasis, inflammation, vesicle trafficking, angiogenesis, and developmental biology. The diverse nature of these molecules underscores the variety of signaling scenarios in which these molecules participate.

Lisa D. Chong (the American Association for the Advancement of Science;Associate Editor of Science's STKE and Science REV)

2001-12-04

171

Magainin 2 channel formation in planar lipid membranes: the role of lipid polar groups and ergosterol  

Microsoft Academic Search

Magainin 2, a polycationic peptide, displays bactericidal and tumoricidal activity, presumably interacting with negatively charged phospholipids in the membrane hosts. In this work, we investigate the role played by the lipid head-group in the interactions and self-association of magainin 2 during pore formation in lipid bilayers. Two methods are used: single-channel and macroscopic incorporation into planar lipid membranes. Single-channel incorporation

Enrico Gallucci; Daniela Meleleo; Silvia Micelli; Vittorio Picciarelli

2003-01-01

172

Role of cholesterol and lipid organization in disease  

Microsoft Academic Search

Membrane lipids are essential for biological functions ranging from membrane trafficking to signal transduction. The composition of lipid membranes influences their organization and properties, so it is not surprising that disorders in lipid metabolism and transport have a role in human disease. Significant recent progress has enhanced our understanding of the molecular and cellular basis of lipid-associated disorders such as

Frederick R. Maxfield; Ira Tabas

2005-01-01

173

Cubic Phase Formation in Phospholipid and PEG-Lipid Mixtures  

Microsoft Academic Search

Lipid systems modeling cell membranes are capable of self-assembling into various liquid crystal mesophases with varying geometry and dimensions. We have suggested that it is possible to engineer the lipid systems through the incorporation of covalently attached polymer lipids to produce unique effects. The results of this engineering process include both the stabilization of lipid phases that normally exist over

Kimberly Murley; Beth Cunningham; David Wolfe; Patrick Williams

2005-01-01

174

What determines drug solubility in lipid vehicles: Is it predictable?  

Microsoft Academic Search

Lipid-based drug delivery systems are of increasing interest to the pharmaceutical scientist because of their potential to solubilize drug molecules that may be otherwise difficult to develop. The ability to predict lipid solubility is an important step in being able to identify the right excipients to solubilize and formulate drugs in lipid formulations. However, predicting lipid solubility is complicated by

Sagar S. Rane; Bradley D. Anderson

2008-01-01

175

Voltage-Gated Lipid Ion Channels  

PubMed Central

Synthetic lipid membranes can display channel-like ion conduction events even in the absence of proteins. We show here that these events are voltage-gated with a quadratic voltage dependence as expected from electrostatic theory of capacitors. To this end, we recorded channel traces and current histograms in patch-experiments on lipid membranes. We derived a theoretical current-voltage relationship for pores in lipid membranes that describes the experimental data very well when assuming an asymmetric membrane. We determined the equilibrium constant between closed and open state and the open probability as a function of voltage. The voltage-dependence of the lipid pores is found comparable to that of protein channels. Lifetime distributions of open and closed events indicate that the channel open distribution does not follow exponential statistics but rather power law behavior for long open times. PMID:23823188

Blicher, Andreas; Heimburg, Thomas

2013-01-01

176

ER stress and hepatic lipid metabolism  

PubMed Central

The endoplasmic reticulum (ER) is an important player in regulating protein synthesis and lipid metabolism. Perturbation of ER homeostasis, referred as “ER stress,” has been linked to numerous pathological conditions, such as inflammation, cardiovascular diseases, and metabolic disorders. The liver plays a central role in regulating nutrient and lipid metabolism. Accumulating evidence implicates that ER stress disrupts lipid metabolism and induces hepatic lipotoxicity. Here, we review the major ER stress signaling pathways, how ER stress contributes to the dysregulation of hepatic lipid metabolism, and the potential causative mechanisms of ER stress in hepatic lipotoxicity. Understanding the role of ER stress in hepatic metabolism may lead to the identification of new therapeutic targets for metabolic diseases. PMID:24847353

Zhou, Huiping; Liu, Runping

2014-01-01

177

Intercellular Lipid Mediators and GPCR Drug Discovery  

PubMed Central

G-protein-coupled receptors (GPCR) are the largest superfamily of receptors responsible for signaling between cells and tissues, and because they play important physiological roles in homeostasis, they are major drug targets. New technologies have been developed for the identification of new ligands, new GPCR functions, and for drug discovery purposes. In particular, intercellular lipid mediators, such as, lysophosphatidic acid and sphingosine 1-phosphate have attracted much attention for drug discovery and this has resulted in the development of fingolimod (FTY-720) and AM095. The discovery of new intercellular lipid mediators and their GPCRs are discussed from the perspective of drug development. Lipid GPCRs for lysophospholipids, including lysophosphatidylserine, lysophosphatidylinositol, lysophosphatidylcholine, free fatty acids, fatty acid derivatives, and other lipid mediators are reviewed. PMID:24404331

Im, Dong-Soon

2013-01-01

178

Modeling Mechanotunable Transmembrane Transport in Lipid Vesicles  

NASA Astrophysics Data System (ADS)

Using Dissipative Particle Dynamics approach, we study the effects of applied stress on transmembrane transport in lipid vesicles. The lipids comprising the vesicle are composed of a hydrophilic head group and two hydrophobic tails. The vesicle is immersed into the hydrophilic solution and initially contains a number of amphiphilic species inside its cavity. We show that such enclosed species can be released ``on demand'' by vesicle's stretching. We find that the magnitude of the external force required to release the vesicle's content depends on the chemical nature and volume fraction of the enclosed species. Furthermore, we isolate the scenarios where the stretching of the lipid vesicle depleted of the enclosed species results in its ``refilling'' with the fresh species from the outer solution. Our results illustrate that applied mechanical stress provides an effective means to fine tune the transmembrane transport in lipid vesicles.

Salib, Isaac G.; Kuksenok, Olga; Balazs, Anna C.

2012-02-01

179

Lipids and the Endothelium: Bidirectional Interactions  

PubMed Central

The endothelium is often viewed solely as the barrier that prevents the penetration of circulating lipoproteins into the arterial wall. However, recent research has demonstrated that the endothelium both takes an important part in regulating circulating fatty acids and lipoproteins, and is in turn affected by these lipids/lipoproteins in ways that appear to have important repercussions for atherosclerosis. Thus, a number of potentially toxic lipids are produced during lipolysis of lipoproteins at the endothelial cell surface. Catabolism of triglyceride-rich lipoproteins creates free fatty acids that are readily taken up by endothelial cells, and, likely through the action of acyl-CoA synthetases, exacerbate inflammatory processes. In this article, we will review how endothelium participates in lipoprotein metabolism, how lipids alter endothelial functions, and how lipids are internalized, processed and transported into the subendothelial space. Finally, we will address the many endothelial changes that might promote atherogenesis, especially in the setting of diabetes. PMID:24037142

Goldberg, Ira J.

2013-01-01

180

Role of epoxide hydrolases in lipid metabolism  

PubMed Central

Epoxide hydrolases (EH), enzymes present in all living organisms, transform epoxide-containing lipids to 1,2-diols by the addition of a molecule of water. Many of these oxygenated lipid substrates have potent biological activities: host defense, control of development, regulation of blood pressure, inflammation, and pain. In general, the bioactivity of these natural epoxides is significantly reduced upon metabolism to diols. Thus, through the regulation of the titer of lipid epoxides, EHs have important and diverse biological roles with profound effects on the physiological state of the host organism. This review will discuss the biological activity of key lipid epoxides in mammals. In addition, the use of EH specific inhibitors will be highlighted as possible therapeutic disease interventions. PMID:22722082

Morisseau, Christophe

2012-01-01

181

Composite S-layer lipid structures  

PubMed Central

Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at meso- and macroscopic scale. In this review, we provide a state of the art survey how S-layer proteins, lipids, and polysaccharides may be used as basic building blocks for the assembly of S-layer supported lipid membranes. These biomimetic membrane systems are distinguished by a nanopatterned fluidity, enhanced stability and longevity and thus, provide a dedicated reconstitution matrix for membrane-active peptides and transmembrane proteins. Exciting areas for application of composite S-layer membrane systems concern sensor systems involving specific membrane functions. PMID:19303933

Schuster, Bernhard; Sleytr, Uwe B.

2010-01-01

182

Formation of polycyclic aromatic hydrocarbons in the smoke from heated model lipids and food lipids.  

PubMed

The contents of polycyclic aromatic hydrocarbons (PAHs) in the smoke from model lipids and food lipids during heating were determined and the mechanism of PAH formation was studied. A Rancimat oil stability analyzer was used as a model system for heating model lipids and food lipids at 220 degrees C for 2 h and for adsorption of smoke. The various lipid degradation products and PAHs in the smoke were identified and quantified by a GC/MS technique. Results showed that model lipids were more susceptible to smoke formation than food lipids during heating, but the PAH levels were lower for the former than latter. Methyl linolenate produced the highest amount of PAHs, followed by methyl linoleate, methyl oleate, and methyl stearate. Also, soybean oil generated a larger amount of PAHs than canola oil or sunflower oil. Benzene-like compounds were found to be possible precursors for PAHs formation. Several PAH derivatives were also present in heated model lipids and food lipids. PMID:11714310

Chen, B H; Chen, Y C

2001-11-01

183

A Role for Lipid Shells in Targeting Proteins to Caveolae, Rafts, and Other Lipid Domains  

NSDL National Science Digital Library

The surface membrane of cells is studded with morphologically distinct regions, or domains, like microvilli, cell-cell junctions, and coated pits. Each of these domains is specialized for a particular function, such as nutrient absorption, cell-cell communication, and endocytosis. Lipid domains, which include caveolae and rafts, are one of the least understood membrane domains. These domains are high in cholesterol and sphingolipids, have a light buoyant density, and function in both endocytosis and cell signaling. A major mystery, however, is how resident molecules are targeted to lipid domains. Here, we propose that the molecular address for proteins targeted to lipid domains is a lipid shell.

Richard G. W. Anderson (University of Texas Southwestern Medical Center, University of North Carolina School of Medicine;Department of Cell Biology, Department of Cell and Developmental Biology and Lineberger Comprehensive Cancer Center); Ken Jacobson (University of Texas Southwestern Medical Center, University of North Carolina School of Medicine;Department of Cell Biology, Department of Cell and Developmental Biology and Lineberger Comprehensive Cancer Center)

2008-06-07

184

Metabolic engineering of lipid catabolism increases microalgal lipid accumulation without compromising growth.  

PubMed

Biologically derived fuels are viable alternatives to traditional fossil fuels, and microalgae are a particularly promising source, but improvements are required throughout the production process to increase productivity and reduce cost. Metabolic engineering to increase yields of biofuel-relevant lipids in these organisms without compromising growth is an important aspect of advancing economic feasibility. We report that the targeted knockdown of a multifunctional lipase/phospholipase/acyltransferase increased lipid yields without affecting growth in the diatom Thalassiosira pseudonana. Antisense-expressing knockdown strains 1A6 and 1B1 exhibited wild-type-like growth and increased lipid content under both continuous light and alternating light/dark conditions. Strains 1A6 and 1B1, respectively, contained 2.4- and 3.3-fold higher lipid content than wild-type during exponential growth, and 4.1- and 3.2-fold higher lipid content than wild-type after 40 h of silicon starvation. Analyses of fatty acids, lipid classes, and membrane stability in the transgenic strains suggest a role for this enzyme in membrane lipid turnover and lipid homeostasis. These results demonstrate that targeted metabolic manipulations can be used to increase lipid accumulation in eukaryotic microalgae without compromising growth. PMID:24248374

Trentacoste, Emily M; Shrestha, Roshan P; Smith, Sarah R; Glé, Corine; Hartmann, Aaron C; Hildebrand, Mark; Gerwick, William H

2013-12-01

185

PAT proteins, an ancient family of lipid droplet proteins that regulate cellular lipid stores  

PubMed Central

Summary The PAT family of lipid droplet proteins includes 5 members in mammals: perilipin, adipose differentiation-related protein (ADRP), tail-interacting protein of 47 kiloDaltons (TIP47), S3-12, and OXPAT. Members of this family are also present in evolutionarily distant organisms, including insects, slime molds and fungi. All PAT proteins share sequence similarity and the ability to bind intracellular lipid droplets, either constitutively or in response to metabolic stimuli, such as increased lipid flux into or out of lipid droplets. Positioned at the lipid droplet surface, PAT proteins manage access of other proteins (lipases) to the lipid esters within the lipid droplet core and can interact with cellular machinery important for lipid droplet biogenesis. Genetic variations in the gene for the best characterized of the mammalian PAT proteins, perilipin, have been associated with metabolic phenotypes, including type 2 diabetes mellitus and obesity. In this review, we discuss how the PAT proteins regulate cellular lipid metabolism both in mammals and in model organisms. PMID:19375517

Bickel, Perry E.; Tansey, John T.; Welte, Michael A.

2009-01-01

186

Chemical Synthesis and Biological Function of Lipidated Proteins.  

PubMed

Lipidated proteins play a key role in many essential biological processes in eukaryotic cells, including signal transduction, membrane trafficking, immune response and pathology. The investigation of the function of lipidated proteins requires access to a reasonable amount of homogenous lipid-modified proteins with defined structures and functional groups. Chemical approaches have provided useful tools to perform such studies. In this review we summarize synthetic methods of lipidated peptides and developments in the chemoselective ligation for the production of lipidated proteins. We introduce the biology of lipidated proteins and highlight the application of synthetic lipidated proteins to tackle important biological questions. PMID:25467536

Yang, Aimin; Zhao, Lei; Wu, Yao-Wen

2014-12-01

187

Hypersaline Microbial Mat Lipid Biomarkers  

NASA Technical Reports Server (NTRS)

Lipid biomarkers and compound specific isotopic abundances are powerful tools for studies of contemporary microbial ecosystems. Knowledge of the relationship of biomarkers to microbial physiology and community structure creates important links for understanding the nature of early organisms and paleoenvironments. Our recent work has focused on the hypersaline microbial mats in evaporation ponds at Guerrero Negro, Baja California Sur, Mexico. Specific biomarkers for diatoms, cyanobacteria, archaea, green nonsulfur (GNS), sulfate reducing, sulfur oxidizing and methanotrophic bacteria have been identified. Analyses of the ester-bound fatty acids indicate a highly diverse microbial community, dominated by photosynthetic organisms at the surface. The delta C-13 of cyanobacterial biomarkers such as the monomethylalkanes and hopanoids are consistent with the delta C-13 measured for bulk mat (-10%o), while a GNS biomarker, wax esters (WXE), suggests a more depleted delta C-13 for GNS biomass (-16%o). This isotopic relationship is different than that observed in mats at Octopus Spring, Yellowstone National Park (YSNP) where GNS appear to grow photoheterotrophic ally. WXE abundance, while relatively low, is most pronounced in an anaerobic zone just below the cyanobacterial layer. The WXE isotope composition at GN suggests that these bacteria utilize photoautotrophy incorporating dissolved inorganic carbon (DIC) via the 3-hydroxypropionate pathway using H2S or H2.

Jahnke, Linda L.; Embaye, Tsegereda; Turk, Kendra A.; Summons, Roger E.

2002-01-01

188

Pediatric aspects of lipid-induced atherogenesis.  

PubMed

There is a need to protect our young from an atherogenic way of life. Atherosclerosis and its precursors have their onset in childhood. Correctable risk factors have been identified that have been shown to exert greater impact early in life than later. Optimal levels of these risk factors for children are being established. The rise in serum lipids, blood pressure, body fat, and blood sugar observed in transition from childhood to adult life is neither inevitable nor desirable. Cardiovascular disease in adults may well begin in childhood with medical trivia such as a tendency to obesity, moderate lipid aberrations, blood pressure elevation, lack of exercise, and the cigarette habit. Recent evidence continues to emphasize blood lipids in atherogenesis. A large amount of cholesterol in the high density lipid (HDL) fraction is protective while the cholesterol in the low density lipid (LDL) is atherogenic. Optimal total cholesterol/HDL cholesterol ratios are in the vicinity of 3.5, corresponding to half the adult average risk in the United States. Worldwide evidence suggests that adult cholesterol values of 180-200 mg/dl are associated with both a low coronary heart disease (CHD) mortality and favorable overall health. In order to achieve this, 140 mg/dl values are needed in children whose blood lipids tend to track into adult life. The rise in serum lipids and deterioration in the LDL/HDL ratio in transition from childhood to adult life seems preventable through hygienic means in childhood when faulty life-styles that promote lipid-induced atherogenesis are conditioned. PMID:6470354

Kannel, W B

1984-01-01

189

Hedgehog Signaling: A Tale of Two Lipids  

NSDL National Science Digital Library

Hedgehog proteins constitute one of the major classes of intercellular signals that control inductive interactions during animal development. These proteins undergo unusual lipid modifications and signal through an unconventional transmembrane protein receptor that is characterized by a sequence motif implicated in sterol sensing. Recent studies suggest that the lipid adducts regulate the range and potency of the signals, whereas the sterol-sensing domain is essential for receptor activity.

Philip Ingham (University of Sheffield;Medical Research Council (MRC) Intercellular Signalling Group, Centre for Developmental Genetics, School of Medicine and Biomedical Science)

2001-11-30

190

Perfluorooctanoic acid rigidifies a model lipid membrane  

E-print Network

We report a combined dynamic light scattering and neutron spin-echo (NSE) study on vesicles composed of the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine under the influence of varying amounts of perfluorooctanoic acid. We study local lipid bilayer undulations using NSE on time scales up to 200 ns. Similar to the effect evoked by cholesterol, we attribute the observed lipid bilayer stiffening to a condensing effect of the perfluorinated compound on the membrane.

Beate-Annette Bruening; Bela Farago

2014-05-05

191

Lipids of the seeds of Cynoglossum officinale  

Microsoft Academic Search

The compositions of the lipids and fatty acids of the seeds ofCynoglossum officinale, familyBoraginaceae have been established. The bulk of the lipids consisted of netural compounds (95.2%), while the amounts of glycolipids and\\u000a phospholipids were 3.1 and 1.7%, respectively. Among the fatty acids, in addition to the usual components, acids characteristic\\u000a for theBoraginaceae family have been found: 18:3 (6, 9,

N. T. Ul'chenko; I. P. Nazarova; A. I. Glushenkova; F. F. Fatkhiev; G. A. Tolstikov

1991-01-01

192

Membrane Cholesterol, Protein Phosphorylation, and Lipid Rafts  

NSDL National Science Digital Library

The functions of cholesterol and membrane microdomains in transmembrane signaling remain controversial. Edidin discusses the questions surrounding lipid rafts, membrane microdomains that have been biochemically defined but are difficult to visualize in vivo. He also discusses whether experiments showing correlation of changes in plasma membrane cholesterol with differentiation and the formation of adherens junctions in endothelial cells are consistent with a model in which lipid rafts influence the regulation of these processes.

Michael Edidin (Johns Hopkins University; Department of Biology REV)

2001-01-30

193

Serum lipid levels in seasonal affective disorder  

Microsoft Academic Search

Previous research has assessed the relationship between blood lipid levels and depression with contradictory results. Several\\u000a studies have linked low cholesterol levels with impulsive, aggressive and suicidal behaviours. The aim of this pilot study\\u000a was to examine serum lipids in a sample of patients suffering from seasonal affective disorder (SAD). We conducted a retrospective\\u000a analysis of data on total serum

Edda Pjrek; Dietmar Winkler; David W. Abramson; Anastasios Konstantinidis; Jürgen Stastny; Matthäus Willeit; Nicole Praschak-Rieder; Siegfried Kasper

2007-01-01

194

RHODOPSIN-LIPID INTERACTIONS STUDIED BY NMR  

PubMed Central

The biophysical properties of the lipid matrix are known to influence function of integral membrane proteins. We report on a sample preparation method for reconstitution of membrane proteins which uses porous anodic aluminum oxide (AAO) filters with 200 nm-wide pores of high density. The substrate permits formation of tubular, single membranes that line the inner surface of pores. One square centimeter of filter with a thickness of 60 ?m yields on the order of 500 cm2 of solid-supported single bilayer surface, sufficient for NMR studies. The tubular bilayers are free of detergent, fully hydrated and accessible for ligands from one side of the membrane. The use of AAO filters greatly improves reproducibility of the reconstitution process such that the influence of protein on lipid order parameters can be studied with high resolution. As an example, results for the G protein-coupled receptor of class A, bovine rhodopsin, are shown. By 2H NMR order parameter measurements it is detected that rhodopsin insertion elastically deforms membranes near the protein. Furthermore, by 1H saturation-transfer NMR under conditions of magic-angle spinning (MAS), we demonstrate detection of preferences in interactions of rhodopsin with particular lipid species. It is assumed that function of integral membrane proteins depends on both protein-induced elastic deformations of the lipid matrix and preferences for interaction of the protein with particular lipid species in the first layer of lipids surrounding the protein. PMID:23374188

Soubias, Olivier; Gawrisch, Klaus

2012-01-01

195

Bending and Puncturing the Influenza Lipid Envelope  

PubMed Central

Lysosomes, enveloped viruses, as well as synaptic and secretory vesicles are all examples of natural nanocontainers (diameter ? 100 nm) which specifically rely on their lipid bilayer to protect and exchange their contents with the cell. We have applied methods primarily based on atomic force microscopy and finite element modeling that allow precise investigation of the mechanical properties of the influenza virus lipid envelope. The mechanical properties of small, spherical vesicles made from PR8 influenza lipids were probed by an atomic force microscopy tip applying forces up to 0.2 nN, which led to an elastic deformation up to 20%, on average. The liposome deformation was modeled using finite element methods to extract the lipid bilayer elastic properties. We found that influenza liposomes were softer than what would be expected for a gel phase bilayer and highly deformable: Consistent with previous suggestion that influenza lipids do not undergo a major phase transition, we observe that the stiffness of influenza liposomes increases gradually and weakly (within one order of magnitude) with temperature. Surprisingly, influenza liposomes were, in most cases, able to withstand wall-to-wall deformation, and forces >1 nN were generally required to puncture the influenza envelope, which is similar to viral protein shells. Hence, the choice of a highly flexible lipid envelope may provide as efficient a protection for a viral genome as a stiff protein shell. PMID:21281578

Li, Sai; Eghiaian, Frederic; Sieben, Christian; Herrmann, Andreas; Schaap, Iwan A.T.

2011-01-01

196

Interaction of C(60) fullerene with lipids.  

PubMed

Unsaturated lipids when exposed to air at room temperature undergo a slow autoxidation. When fullerene C(60) was dissolved in selected lipids (ethyl oleate, ethyl linoleate, linseed oil and castor oil) the spectrophotometric analysis shows that the oxidation is concentrated to C(60) which is converted to an epoxide C(60)O. Thus, fullerene C(60) displays antioxidant activity not only when dissolved in unsaturated lipids but also, more generally, when dissolved in unsaturated solvents subjected to autoxidation like, for example, in cyclohexene. The behaviour of C(60) in ethyl oleate has been compared with that of the known antioxidant TMPPD (N,N',N,N,'-tetramethyl-p-phenylenediamine) in ethyl oleate. The mechanism of the antioxidant action of C(60) in lipids has been proposed. The kinetics of C(60) oxidation in lipids was determined spectrophotometrically both at room temperature in the dark and under UV irradiation. The oxidized products derived from C(60) photo-oxidation in lipids have been identified. PMID:20338159

Cataldo, Franco

2010-06-01

197

Composition, accumulation and utilization of yolk lipids in teleost fish  

Microsoft Academic Search

Lipid reserves in teleost eggs are stored in lipoprotein yolk and, in some species, a discrete oil globule. Lipoprotein yolk lipids are primarily polar lipids, especially phosphatidylcholine and phosphatidylethanolamine (PE), and are rich in (n-3) polyunsaturated fatty acids, especially 22:6(n-3) (docosahexaenoic acid, DHA). Oil consists of neutral lipids and is rich in monounsaturated fatty acids (MUFA). Egg lipids are derived

Murray D. Wiegand

1996-01-01

198

Microalgal lipids biochemistry and biotechnological perspectives.  

PubMed

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 ?-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. PMID:25449285

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

2014-12-01

199

Red clover polyphenol oxidase and lipid metabolism.  

PubMed

Increasing the polyunsaturated fatty acid (PUFA) composition of milk is acknowledged to be of benefit to consumer health. Despite the high PUFA content of forages, milk fat contains only about 3% of PUFA and only about 0.5% of n-3 fatty acids. This is mainly due to intensive lipid metabolism in the rumen (lipolysis and biohydrogenation) and during conservation (lipolysis and oxidation) such as drying (hay) and ensiling (silage). In red clover, polyphenol oxidase (PPO) has been suggested to protect lipids against degradation, both in the silage as well as in the rumen, leading to a higher output of PUFA in ruminant products (meat and milk). PPO mediates the oxidation of phenols and diphenols to quinones, which will readily react with nucleophilic binding sites. Such binding sites can be found on proteins, resulting in the formation of protein-bound phenols. This review summarizes the different methods that have been used to assess PPO activity in red clover, and an overview on the current understanding of PPO activity and activation in red clover. Knowledge on these aspects is of major importance to fully harness PPO's lipid-protecting role. Furthermore, we review the studies that evidence PPO-mediated lipid protection and discuss its possible importance in lab-scale silages and further in an in vitro rumen system. It is demonstrated that high (induction of) PPO activity can lead to lower lipolysis in the silage and lower biohydrogenation in the rumen. There are three hypotheses on its working mechanism: (i) protein-bound phenols could directly bind to enzymes (e.g. lipases) as such inhibiting them; (ii) binding of quinones in and between proteins embedded in a lipid membrane (e.g. in the chloroplast) could lead to encapsulation of the lipids; (iii) direct binding of quinones to nucleophilic sites in polar lipids also could lead to protection. There is no exclusive evidence on which mechanism is most important, although there are strong indications that only lipid encapsulation in protein-phenol complexes would lead to an effective protection of lipids against ruminal biohydrogenation. From several studies it has also become apparent that the degree of PPO activation could influence the mode and degree of protection. In conclusion, this review demonstrates that protein-bound phenols and encapsulation in protein-phenol complexes, induced by PPO-mediated diphenol oxidation, could be of interest when aiming to protect lipids against pre-ruminal and ruminal degradation. PMID:22439947

Van Ranst, G; Lee, M R F; Fievez, V

2011-02-01

200

Cholecystokinin Elevates Mouse Plasma Lipids  

PubMed Central

Cholecystokinin (CCK) is a peptide hormone that induces bile release into the intestinal lumen which in turn aids in fat digestion and absorption in the intestine. While excretion of bile acids and cholesterol into the feces eliminates cholesterol from the body, this report examined the effect of CCK on increasing plasma cholesterol and triglycerides in mice. Our data demonstrated that intravenous injection of [Thr28, Nle31]-CCK at a dose of 50 ng/kg significantly increased plasma triglyceride and cholesterol levels by 22 and 31%, respectively, in fasting low-density lipoprotein receptor knockout (LDLR?/?) mice. The same dose of [Thr28, Nle31]-CCK induced 6 and 13% increases in plasma triglyceride and cholesterol, respectively, in wild-type mice. However, these particular before and after CCK treatment values did not achieve statistical significance. Oral feeding of olive oil further elevated plasma triglycerides, but did not alter plasma cholesterol levels in CCK-treated mice. The increased plasma cholesterol in CCK-treated mice was distributed in very-low, low and high density lipoproteins (VLDL, LDL and HDL) with less of an increase in HDL. Correspondingly, the plasma apolipoprotein (apo) B48, B100, apoE and apoAI levels were significantly higher in the CCK-treated mice than in untreated control mice. Ligation of the bile duct, blocking CCK receptors with proglumide or inhibition of Niemann-Pick C1 Like 1 transporter with ezetimibe reduced the hypercholesterolemic effect of [Thr28, Nle31]-CCK in LDLR?/? mice. These findings suggest that CCK-increased plasma cholesterol and triglycerides as a result of the reabsorption of biliary lipids from the intestine. PMID:23300532

Zhou, Lichun; Yang, Hong; Lin, Xinghua; Okoro, Emmanuel U.; Guo, Zhongmao

2012-01-01

201

Lipids and oxidised lipids in human atherosclerotic lesions at different stages of development  

Microsoft Academic Search

Lipids and oxidised lipids were analysed by GC and GC-MS in human necropsy samples of normal artery and individual atherosclerotic lesions, from aorta and common carotid artery, including fatty streaks, intermediate lesions and advanced lesions. Age-related increases were seen for linoleate, oleate and cholesterol in normal artery, but not in lesions. Each category of lesion was much richer than normal

Keri L. H. Carpenter; Susan E. Taylor; Carina van der Veen; Bridget K. Williamson; James A. Ballantine; Malcolm J. Mitchinson

1995-01-01

202

Cytotoxicity of Solid Lipid Nanoparticles as a Function of the Lipid Matrix and the Surfactant  

Microsoft Academic Search

Purpose. Assessment of the in vitro cytotoxicity of solid lipid nanoparticles (SLNs) as a function of lipid matrix (Dynasan 114, Compritol ATO 888), and stabilizing surfactant (poloxamers, Tween 80, soya lecithin, and sodium dodecyl sulphate). Comparison with other colloidal carriers should determine their potential use in the clinic.

Rainer H. Müller; Dörte Rühl; Stephan Runge; Kai Schulze-Forster; Wolfgang Mehnert

1997-01-01

203

Lipid Membrane Adhesion and Fusion Driven by Designed, Minimally Multivalent Hydrogen-Bonding Lipids  

E-print Network

Lipid Membrane Adhesion and Fusion Driven by Designed, Minimally Multivalent Hydrogen-Bonding) and melamine (M) functionalized lipids can form membranes that exhibit robust hydrogen-bond driven surface bonding when incorporated at 0.1-5 mol percent in fluid phospholipid membranes, inducing both vesicle

Bong, Dennis

204

Lipids . Author manuscript Increased lipid peroxidation in LDL from type-2 diabetic patients  

E-print Network

Lipids . Author manuscript Page /1 10 Increased lipid peroxidation in LDL from type-2 diabetic with type-2 diabetes and related cardiovascular diseases but oxidative modification of LDL has been status of LDL from diabetic patients and healthy subjects. First, to ensure that isolation of LDL

Paris-Sud XI, Université de

205

Lipid Clustering Correlates with Membrane Curvature as Revealed by Molecular Simulations of Complex Lipid Bilayers  

PubMed Central

Cell membranes are complex multicomponent systems, which are highly heterogeneous in the lipid distribution and composition. To date, most molecular simulations have focussed on relatively simple lipid compositions, helping to inform our understanding of in vitro experimental studies. Here we describe on simulations of complex asymmetric plasma membrane model, which contains seven different lipids species including the glycolipid GM3 in the outer leaflet and the anionic lipid, phosphatidylinositol 4,5-bisphophate (PIP2), in the inner leaflet. Plasma membrane models consisting of 1500 lipids and resembling the in vivo composition were constructed and simulations were run for 5 µs. In these simulations the most striking feature was the formation of nano-clusters of GM3 within the outer leaflet. In simulations of protein interactions within a plasma membrane model, GM3, PIP2, and cholesterol all formed favorable interactions with the model ?-helical protein. A larger scale simulation of a model plasma membrane containing 6000 lipid molecules revealed correlations between curvature of the bilayer surface and clustering of lipid molecules. In particular, the concave (when viewed from the extracellular side) regions of the bilayer surface were locally enriched in GM3. In summary, these simulations explore the nanoscale dynamics of model bilayers which mimic the in vivo lipid composition of mammalian plasma membranes, revealing emergent nanoscale membrane organization which may be coupled both to fluctuations in local membrane geometry and to interactions with proteins. PMID:25340788

Koldsø, Heidi; Shorthouse, David; Hélie, Jean; Sansom, Mark S. P.

2014-01-01

206

Designing biorelevant dissolution tests for lipid formulations: Case example – Lipid suspension of RZ-50  

Microsoft Academic Search

Biorelevant dissolution test methods for lipid formulations of RZ-50, an experimental Roche compound, were developed and compared with standard compendial methods in terms of their in vivo predictability. Release of RZ-50, a poorly soluble weakly acidic drug, from lipid suspensions filled in soft gelatin capsules was studied in compendial and biorelevant media using the USP Apparatus 2 (paddle method) and

Ekarat Jantratid; Niels Janssen; Hitesh Chokshi; Kin Tang; Jennifer B. Dressman

2008-01-01

207

Dietary practices and lipid intake in relation to plasma lipid profile in Hong Kong Chinese  

Microsoft Academic Search

Objective: To study dietary lipid intake and plasma lipid profile of the Hong Kong Chinese population as part of a territory wide survey on cardiovascular risk factors. Design: Randomised age and sex stratified survey. Subjects: 1010 subjects aged 25–74 y (500 men, 510 women). Measurements: A food frequency method with food tables compiled for Hong Kong was used for nutrient

J Woo; SSF Leung; SC Ho; A Sham; TH Lam; ED Janus

1997-01-01

208

Phase Behavior of Mixed Lipid Bilayered System  

NSDL National Science Digital Library

Lipid mixtures of short and long amphiphile chains self-assemble in water to form a great variety of structures. The morphology of these structures include phases composed of extended flexible bilayer membrane that may display order by stacking with a periodicity as in the anisotropic lamellar phase, or they may also form bilayered miscelles (or bicelles), bilayered disks formed of a long lipid chain with their edges stabilized by short chain lipid, with diameter of a few hundred angstroms. The lipid mixtures have a great potential in the study of membrane proteins and peptides. These mixtures imitate the physical properties of biological membranes and they are stable over a wide range of temperatures, pH and ionic strength. By having a detailed description of the morphology of the lipid mixtures and understanding their phases will help increase their use in various structural biology techniques. Our goal was to study the effect on transition between the bicelle to lamellar phase by changing the concentration of lipid in the solution. Each sample consisted of molar ratios of DHPC:DMPC:DMPG of 0.2:1:0.067. The concentration of lipid was of 20%, 10% and 5%. The 20% sample has a liquid to gel phase transition temperature of near 25°C. The lamellar phase forms above 25°C. By lowering the sampleâs concentration and by an isotropic substitution of H2O by D2O, we found some intriguing results: the liquid to gel phase transition and lamellar phase temperature shifted. SANS, reflectometry and crossed polarizers were use to study the transition between the bicelle to lamellar phase. With these results, the structure of the phase boundary between the bicelles and lamellar morphology was better understood and characterized.

Rodriguez-Rivera, Veronica

2005-01-01

209

Acquisition of membrane lipids by differentiating glyoxysomes: role of lipid bodies  

PubMed Central

Glyoxysomes in cotyledons of cotton (Gossypium hirsutum, L.) seedlings enlarge dramatically within 48 h after seed imbibition (Kunce, C.M., R.N. Trelease, and D.C. Doman. 1984. Planta (Berl.). 161:156-164) to effect mobilization of stored cotton-seed oil. We discovered that the membranes of enlarging glyoxysomes at all stages examined contained a large percentage (36-62% by weight) of nonpolar lipid, nearly all of which were triacylglycerols (TAGs) and TAG metabolites. Free fatty acids comprised the largest percentage of these nonpolar lipids. Six uncommon (and as yet unidentified) fatty acids constituted the majority (51%) of both the free fatty acids and the fatty acids in TAGs of glyoxysome membranes; the same six uncommon fatty acids were less than 7% of the acyl constituents in TAGs extracted from cotton-seed storage lipid bodies. TAGs of lipid bodies primarily were composed of palmitic, oleic, and linoleic acids (together 70%). Together, these three major storage fatty acids were less than 10% of both the free fatty acids and fatty acids in TAGs of glyoxysome membranes. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) constituted a major portion of glyoxysome membrane phospholipids (together 61% by weight). Pulse-chase radiolabeling experiments in vivo clearly demonstrated that 14C-PC and 14C-PE were synthesized from 14C-choline and 14C-ethanolamine, respectively, in ER of cotyledons, and then transported to mitochondria; however, these lipids were not transported to enlarging glyoxysomes. The lack of ER involvement in glyoxysome membrane phospholipid synthesis, and the similarities in lipid compositions between lipid bodies and membranes of glyoxysomes, led us to formulate and test a new hypothesis whereby lipid bodies serve as the dynamic source of nonpolar lipids and phospholipids for membrane expansion of enlarging glyoxysomes. In a cell-free system, 3H-triolein (TO) and 3H- PC were indeed transferred from lipid bodies to glyoxysomes. 3H-PC, but not 3H-TO, also was transferred to mitochondria in vitro. The amount of lipid transferred increased linearly with respect to time and amount of acceptor organelle protein, and transfer occurred only when lipid body membrane proteins were associated with the donor lipid bodies. 3H-TO was transferred to and incorporated into glyoxysome membranes, and then hydrolyzed to free fatty acids. 3H-PC was transferred to and incorporated into glyoxysome and mitochondria membranes without subsequent hydrolysis. Our data are inconsistent with the hypothesis that ER contributes membrane lipids to glyoxysomes during postgerminative seedling growth.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1955468

1991-01-01

210

Synthesis of Lipids for Development of Multifunctional Lipid-Based Drug-Carriers  

PubMed Central

A simple approach to synthesize phospholipids to modulate drug release and track lipid-based particulate drug-carriers is described. We synthesized two ether lipids, 1 1-O-hexadecyl-2-pentadenoyl-sn-glycerol-3-phosphocholine (C31PC) and 2 1-O-hexadecyl-2-pentadenoyl-sn-glycerol-3-phosphomethanol (C31PM), and examined their ability to alter enzymatically triggered release of 6-carboxyfluorescein from liposomes incubated in TRIS buffer or fetal bovine serum solutions. Further, we demonstrated that odd-chain lipids, e.g., C31PC, could be identified in rat plasma without interference of endogenous lipids. This approach can be adapted to synthesize a variety of lipids for use in developing and optimizing multifunctional drug-carriers. PMID:21955941

Zhu, Guodong; Hamhoom, Yahya Al; Cummings, Brian S.; Arnold, Robert D.

2011-01-01

211

Dividing Cells Regulate Their Lipid Composition and Localization  

PubMed Central

Summary Although massive membrane rearrangements occur during cell division, little is known about specific roles that lipids might play in this process. We report that the lipidome changes with the cell cycle. LC-MS-based lipid profiling shows that 11 lipids with specific chemical structures accumulate in dividing cells. Using AFM, we demonstrate differences in the mechanical properties of live dividing cells and their isolated lipids relative to nondividing cells. In parallel, systematic RNAi knockdown of lipid biosynthetic enzymes identified enzymes required for division, which highly correlated with lipids accumulated in dividing cells. We show that cells specifically regulate the localization of lipids to midbodies, membrane-based structures where cleavage occurs. We conclude that cells actively regulate and modulate their lipid composition and localization during division, with both signaling and structural roles likely. This work has broader implications for the active and sustained participation of lipids in basic biology. PMID:24462247

Atilla-Gokcumen, G. Ekin; Muro, Eleonora; Relat-Goberna, Josep; Sasse, Sofia; Bedigian, Anne; Coughlin, Margaret L.; Garcia-Manyes, Sergi; Eggert, Ulrike S.

2014-01-01

212

The effect of neutral helper lipids on the structure of cationic lipid monolayers  

PubMed Central

Successful drug delivery via lipid-based systems has often been aided by the incorporation of ‘helper lipids’. While these neutral lipids enhance the effectiveness of cationic lipid-based delivery formulations, many questions remain about the nature of their beneficial effects. The structure of monolayers of the cationic lipid dimethyldioctadecylammonium bromide (DODAB) alone, and mixed with a neutral helper lipid, either diolelyphosphatidylethanolamine or cholesterol at a 1 : 1 molar ratio was investigated at the air–water interface using a combination of surface pressure–area isotherms, Brewster angle microscopy (BAM) and specular neutron reflectivity in combination with contrast variation. BAM studies showed that while pure DODAB and DODAB with cholesterol monolayers showed fairly homogeneous surfaces, except in the regions of phase transition, monolayers of DODAB with diolelyphosphatidylethanolamine were, in contrast, inhomogeneous exhibiting irregular bean-shaped domains throughout. Neutron reflectivity data showed that while the thickness of the DODAB monolayer increased from 17 to 24 Å as it was compressed from a surface pressure of 5–40 mN m?1, the thickness of the helper lipid-containing monolayers, over the same range of surface pressures, was relatively invariant at between 25 and 27 Å. In addition, the monolayers containing diolelyphosphatidylethanolamine were found to be more heavily hydrated than the monolayers of cationic lipid, alone or in combination with cholesterol, with hydration levels of 18 molecules of water per molecule of lipid being recorded for the diolelyphosphatidylethanolamine-containing monolayers at a surface pressure of 30 mN m?1 compared with only six and eight molecules of water per molecule of lipid for the pure DODAB monolayer and the cholesterol-containing DODAB monolayer, respectively. PMID:21831895

Dabkowska, A. P.; Barlow, D. J.; Hughes, A. V.; Campbell, R. A.; Quinn, P. J.; Lawrence, M. J.

2012-01-01

213

The molecular mechanism of lipid monolayer collapse  

PubMed Central

Lipid monolayers at an air–water interface can be compressed laterally and reach high surface density. Beyond a certain threshold, they become unstable and collapse. Lipid monolayer collapse plays an important role in the regulation of surface tension at the air–liquid interface in the lungs. Although the structures of lipid aggregates formed upon collapse can be characterized experimentally, the mechanism leading to these structures is not fully understood. We investigate the molecular mechanism of monolayer collapse using molecular dynamics simulations. Upon lateral compression, the collapse begins with buckling of the monolayer, followed by folding of the buckle into a bilayer in the water phase. Folding leads to an increase in the monolayer surface tension, which reaches the equilibrium spreading value. Immediately after their formation, the bilayer folds have a flat semielliptical shape, in agreement with theoretical predictions. The folds undergo further transformation and form either flat circular bilayers or vesicles. The transformation pathway depends on macroscopic parameters of the system: the bending modulus, the line tension at the monolayer–bilayer connection, and the line tension at the bilayer perimeter. These parameters are determined by the system composition and temperature. Coexistence of the monolayer with lipid aggregates is favorable at lower tensions of the monolayer–bilayer connection. Transformation into a vesicle reduces the energy of the fold perimeter and is facilitated for softer bilayers, e.g., those with a higher content of unsaturated lipids, or at higher temperatures. PMID:18669655

Baoukina, Svetlana; Monticelli, Luca; Risselada, H. Jelger; Marrink, Siewert J.; Tieleman, D. Peter

2008-01-01

214

Chemical composition of Desulfovibrio desulfuricans lipid A  

PubMed Central

Lipopolysaccharides also called endotoxins are an integral component of the outer membrane of Gram-negative bacteria. When released from the bacterial surface, they interact with a host immune system, triggering excessive inflammatory response. Lipid A is the biologically most active part of endotoxin, and its activity is modulated by the quantity, quality and arrangement of its fatty acids. Desulfovibrio desulfuricans is sulfate-reducing, Gram-negative bacterium that is supposed to be opportunistic pathogens of humans and animals. In the present study, chemical composition of lipid A from various strains of D. desulfuricans was analyzed by gas chromatography/mass spectrometry. It was found that the fatty acid component of the lipid A contains dodecanoic, tetradecanoic, 3-hydroxytetradecanoic and hexadecanoic acids, and its carbohydrate core is composed of glucosamine. The analysis of 3-acyloxyacyl residue of the lipid A revealed the presence of amide-bound 3-(dodecanoyloxy)tetradecanoic and 3-(hexadecanoyloxy)tetradecanoic acids and ester-bound 3-(tetradecanoyloxy)tetradecanoic acid. It was concluded that both fatty acid and 3-acyloxyacyl residue profiles of the lipid A from the studied bacteria were similar to those of E. coli and S.enterica. PMID:20978743

Lodowska, Jolanta; Jaworska-Kik, Marzena; Kurkiewicz, S?awomir; W?glarz, Ludmi?a; Dzier?ewicz, Zofia

2010-01-01

215

Intravenous Lipids for Preterm Infants: A Review  

PubMed Central

Extremely low birth weight infants (ELBW) are born at a time when the fetus is undergoing rapid intrauterine brain and body growth. Continuation of this growth in the first several weeks postnatally during the time these infants are on ventilator support and receiving critical care is often a challenge. These infants are usually highly stressed and at risk for catabolism. Parenteral nutrition is needed in these infants because most cannot meet the majority of their nutritional needs using the enteral route. Despite adoption of a more aggressive approach with amino acid infusions, there still appears to be a reluctance to use early intravenous lipids. This is based on several dogmas that suggest that lipid infusions may be associated with the development or exacerbation of lung disease, displace bilirubin from albumin, exacerbate sepsis, and cause CNS injury and thrombocytopena. Several recent reviews have focused on intravenous nutrition for premature neonate, but very little exists that provides a comprehensive review of intravenous lipid for very low birth and other critically ill neonates. Here, we would like to provide a brief basic overview, of lipid biochemistry and metabolism of lipids, especially as they pertain to the preterm infant, discuss the origin of some of the current clinical practices, and provide a review of the literature, that can be used as a basis for revising clinical care, and provide some clarity in this controversial area, where clinical care is often based more on tradition and dogma than science.

Salama, Ghassan SA; Kaabneh, Mahmmoud AF; Almasaeed, Mai N; Alquran, Mohammad IA

2015-01-01

216

Modified lipid and protein dynamics in nanodiscs.  

PubMed

For membrane protein studies, nanodiscs have been shown to hold great potential in terms of preparing soluble samples while maintaining a lipid environment. Here, we describe the differences in lipid order and protein dynamics in MSP1 nanodiscs compared to lamellar preparations by solid-state NMR. For DMPC, an increase of the dipolar C-H lipid acyl chain order parameters in nanodiscs is observed in both gel- and liquid crystalline phases. Incorporating proteorhodopsin in these nanodiscs resulted in a significantly longer rotating frame spin-lattice relaxation time for (13)C leerzeichen and better cross polarisation efficiency due to restricted protein dynamics. A comparison of (13)C-(13)C correlation spectra revealed no structural differences. The incorporation of proteorhodopsin into nanodiscs has been optimised with respect to detergent and to protein/scaffold protein/lipid stoichiometries. Its functional state was probed by time-resolved optical spectroscopy revealing only minor differences between lamellar and nanodisc preparations. Our observations show remarkable dynamic effects between membrane proteins, lipids and scaffold protein. The potential use of nanodiscs for solid-state NMR applications is discussed. PMID:23276833

Mörs, Karsten; Roos, Christian; Scholz, Frank; Wachtveitl, Josef; Dötsch, Volker; Bernhard, Frank; Glaubitz, Clemens

2013-04-01

217

Intercellular lamellar lipids in plantar stratum corneum.  

PubMed

Plantar stratum corneum was examined by means of transmission electron microscopy after conventional osmium fixation and after fixation with ruthenium tetroxide. The latter fixative was used in order to reveal the possible existence of lamelarly ordered lipids in the intercellular space, as has previously been demonstrated for non-palmo-plantar stratum corneum. A major part of the plantar stratum corneum intercellular space was occupied by extracellular parts of desmosomes. In specimens fixed with ruthenium tetroxide the intercellular space not occupied by desmosomes was found to contain multiple alternating electron dense and electron lucid bands, suggestive of membraneous structures. This pattern appeared to be similar to that previously described for non-palmo-plantar stratum corneum. It is suggested that the intercellular lipids of palmo-plantar stratum corneum may be qualitatively similar to the intercellular lipids of non-palmo-plantar stratum corneum. The lower lipid content, expressed as weight per unit weight of tissue, in palmo-plantar stratum corneum as compared to non-palmo-plantar stratum corneum may be related to the fact that a larger portion of the intercellular space of the former tissue is occupied by desmosomes. The relatively high water permeability of palmo-plantar stratum corneum implies that desmosomes, i.e. non-lipid regions of the intercellular space, may have a high water permeability and hence could establish a hydrophilic route through the stratum corneum. PMID:1684462

Egelrud, T; Lundström, A

1991-01-01

218

Lipid binding proteins from parasitic platyhelminthes  

PubMed Central

Two main families of lipid binding proteins have been identified in parasitic Platyhelminthes: hydrophobic ligand binding proteins (HLBPs) and fatty acid binding proteins (FABPs). Members of the former family of proteins are specific to the Cestoda class, while FABPs are conserved across a wide range of animal species. Because Platyhelminthes are unable to synthesize their own lipids, these lipid-binding proteins are important molecules in these organisms. HLBPs are a high molecular mass complex of proteins and lipids. They are composed of subunits of low molecular mass proteins and a wide array of lipid molecules ranging from CoA esters to cholesterol. These proteins are excretory-secretory molecules and are key serological tools for diagnosis of diseases caused by cestodes. FABPs are mainly intracellular proteins of low molecular weight. They are also vaccine candidates. Despite that the knowledge of their function is scarce, the differences in their molecular organization, ligand preferences, intra/extracellular localization, evolution, and phylogenetic distribution, suggest that platyhelminths HLBPs and FABPs should play different functions. FABPs might be involved in the removal of fatty acids from the inner surface of the cell membrane and in their subsequent targeting to specific cellular destinations. In contrast, HLBPs might be involved in fatty acid uptake from the host environment. PMID:22988444

Alvite, Gabriela; Esteves, Adriana

2012-01-01

219

Inositol lipids and DNA replication.  

PubMed

Control of DNA synthesis by growth factors seems to depend upon the generation of intracellular mitogenic signals, which are responsible for initiating the sequence of events leading to the onset of DNA synthesis. Many growth factors have tyrosine kinase activity suggesting the proteins phosphorylated on tyrosine might be likely candidates as intracellular signals. Other candidates are the calcium and hydrogen ions whose concentrations change dramatically during the action of most growth factors, many of which also stimulate the hydrolysis of inositol lipids. In particular, certain growth factors stimulate the hydrolysis of phosphatidylinositol 4,5-bisphosphate to give the two second messengers diacylglycerol and inositol 1,4,5-trisphosphate (Ins1,4,5P3). The former stimulates protein kinase C, which is responsible for increasing intracellular pH by switching on an Na+-H+ exchanger. The water-soluble Ins1,4,5P3 released to the cytosol can be metabolized along two separate pathways: it can either be dephosphorylated to free inositol or it can be converted into additional inositol polyphosphates such as Ins1,3,4,5P4 and Ins1,3,4P3. These inositol phosphates seem to play a key role in regulating intracellular calcium, with Ins1,4,5P3 functioning to release internal calcium, whereas Ins1,3,4,5P4 may function to regulate the entry of external calcium. There is evidence to suggest that these internal messengers may converge on certain key processes responsible for initiating the programme of cell growth. It is argued that an increase in intracellular calcium might be an important intracellular signal for activating both the transcription of a family of early genes, typified by fos, as well as the enzyme S6 kinase, which phosphorylates the ribosomal protein S6 which may regulate protein synthesis. The increase in pH seems to play a permissive role and may create the necessary ionic milieu for S6 phosphorylation and protein synthesis to occur. The onset of RNA and protein synthesis, which occur within the first few minutes after the arrival of a growth factor, represent the initial events of the programme of cell growth which culminates in DNA synthesis and cell division. PMID:2894687

Berridge, M J

1987-12-15

220

A peroxisome biogenesis deficiency prevents the binding of alpha-synuclein to lipid droplets in lipid-loaded yeast  

PubMed Central

Using a yeast model of Parkinson’s disease, we found that alpha-synuclein (?S) binds to lipid droplets in lipid-loaded, wild-type yeast cells but not to lipid droplet in lipid-loaded, peroxisome-deficient cells (pex3?).Our analysis revealed that pex3? cells have both fewer lipid droplets and smaller lipid droplets than wild-type cells, and that the acyl chains of the phospholipids on the surface of the lipid droplets from pex3? cells are on average shorter (C16) than those (C18) on the surface of lipid droplets from wild-type cells. We propose that the shift to shorter (C18? C16) acyl chains contributes to the reduced binding of ?S to lipid droplets in pex3? cells. PMID:23916615

Wang, Shaoxiao; Horn, Patrick J.; Liou, Liang-Chun; Muggeridge, Martin I.; Zhang, Zhaojie; Chapman, Kent D.; Witt, Stephan N.

2013-01-01

221

New insights on glucosylated lipids: metabolism and functions.  

PubMed

Ceramide, cholesterol, and phosphatidic acid are major basic structures for cell membrane lipids. These lipids are modified with glucose to generate glucosylceramide (GlcCer), cholesterylglucoside (ChlGlc), and phosphatidylglucoside (PtdGlc), respectively. Glucosylation dramatically changes the functional properties of lipids. For instance, ceramide acts as a strong tumor suppressor that causes apoptosis and cell cycle arrest, while GlcCer has an opposite effect, downregulating ceramide activities. All glucosylated lipids are enriched in lipid rafts or microdomains and play fundamental roles in a variety of cellular processes. In this review, we discuss the biological functions and metabolism of these three glucosylated lipids. PMID:23770033

Ishibashi, Yohei; Kohyama-Koganeya, Ayako; Hirabayashi, Yoshio

2013-09-01

222

Peptide-Lipid Interactions: Experiments and Applications  

PubMed Central

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

Galdiero, Stefania; Falanga, Annarita; Cantisani, Marco; Vitiello, Mariateresa; Morelli, Giancarlo; Galdiero, Massimiliano

2013-01-01

223

mitochondrial pathway for biosynthesis of lipid mediators  

PubMed Central

The central role of mitochondria in metabolic pathways and in cell death mechanisms requires sophisticated signaling systems. Essential in this signaling process is an array of lipid mediators derived from polyunsaturated fatty acids. However, the molecular machinery for the production of oxygenated polyunsaturated fatty acids is localized in the cytosol and their biosynthesis has not been identified in mitochondria. Here we report that a range of diversified polyunsaturated molecular species derived from a mitochondria-specific phospholipid, cardiolipin, are oxidized by the intermembrane space hemoprotein, cytochrome c. We show that an assortment of oxygenated cardiolipin species undergoes phospholipase A2-catalyzed hydrolysis thus generating multiple oxygenated fatty acids, including well known lipid mediators. This represents a new biosynthetic pathway for lipid mediators. We demonstrate that this pathway including oxidation of polyunsaturated cardiolipins and accumulation of their hydrolysis products – oxygenated linoleic, arachidonic acids and monolyso-cardiolipins – is activated in vivo after acute tissue injury. PMID:24848241

Tyurina, Yulia Y.; Poloyac, Samuel M.; Tyurin, Vladimir A.; Kapralov, Alexander A.; Jiang, Jianfei; Anthonymuthu, Tamil Selvan; Kapralova, Valentina I.; Vikulina, Anna S.; Jung, Mi-Yeon; Epperly, Michael W.; Mohammadyani, Dariush; Klein-Seetharaman, Judith; Jackson, Travis C.; Kochanek, Patrick M.; Pitt, Bruce R.; Greenberger, Joel S.; Vladimirov, Yury A.; Bay?r, Hülya; Kagan, Valerian E.

2014-01-01

224

Apolipoprotein gene involved in lipid metabolism  

DOEpatents

Methods and materials for studying the effects of a newly identified human gene, APOAV, and the corresponding mouse gene apoAV. The sequences of the genes are given, and transgenic animals which either contain the gene or have the endogenous gene knocked out are described. In addition, single nucleotide polymorphisms (SNPs) in the gene are described and characterized. It is demonstrated that certain SNPs are associated with diseases involving lipids and triglycerides and other metabolic diseases. These SNPs may be used alone or with SNPs from other genes to study individual risk factors. Methods for intervention in lipid diseases, including the screening of drugs to treat lipid-related or diabetic diseases are also disclosed.

Rubin, Edward (Berkeley, CA); Pennacchio, Len A. (Sebastopol, CA)

2007-07-03

225

Golgi membrane dynamics and lipid metabolism.  

PubMed

The striking morphology of the Golgi complex has fascinated cell biologists since its discovery over 100 years ago. Yet, despite intense efforts to understand how membrane flow relates to Golgi form and function, this organelle continues to baffle cell biologists and biochemists alike. Fundamental questions regarding Golgi function, while hotly debated, remain unresolved. Historically, Golgi function has been described from a protein-centric point of view, but we now appreciate that conceptual frameworks for how lipid metabolism is integrated with Golgi biogenesis and function are essential for a mechanistic understanding of this fascinating organelle. It is from a lipid-centric perspective that we discuss the larger question of Golgi dynamics and membrane trafficking. We review the growing body of evidence for how lipid metabolism is integrally written into the engineering of the Golgi system and highlight questions for future study. PMID:22625862

Bankaitis, Vytas A; Garcia-Mata, Rafael; Mousley, Carl J

2012-05-22

226

Controlling lipid micelle stability using oligonucleotide headgroups.  

PubMed

Lipid-based micelles provide an attractive option for therapeutic and diagnostic applications because of their small size (<20 nm) and ability to self-assemble and improve the solubility of both hydrophobic drugs and dyes. Their use, however, has been challenged by the fact that these particles are inherently unstable in serum becaue of interactions with protein components, which drives the micelle equilibrium to the monomeric state. We have engineered serum stabilized micelles using short quadruplex forming oligonucleotide extensions as the lipid headgroup. Quadruplex formation on the surface of the particles, confirmed by (1)H NMR, results in slight distortion of the otherwise spherical micelles and renders them resistant to disassembly by serum proteins for >24 h. Using antisense oligonucleotides we demonstrated that disruption of the quadruplex leads to micelle destabilization and cargo release. The ability to use oligonucleotide interactions to control lipid particle stability represents a new approach in the design of programmed nanoscale devices. PMID:25634639

Wilner, Samantha E; Sparks, Samuel E; Cowburn, David; Girvin, Mark E; Levy, Matthew

2015-02-18

227

Lipid Anti-Lipid Antibody Responses Correlate with Disease Activity in Systemic Lupus Erythematosus  

PubMed Central

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disorder characterized by broad clinical manifestations including cardiovascular and renal complications with periodic disease flares and significant morbidity and mortality. One of the main contributing factors to the pathology of SLE is the accumulation and impaired clearance of immune complexes of which the principle components are host auto-antigens and antibodies. The contribution of host lipids to the formation of these autoimmune complexes remains poorly defined. The aim of the present study was to identify and analyze candidate lipid autoantigens and their corresponding anti–lipid antibody responses in a well-defined SLE patient cohort using a combination of immunological and biophysical techniques. Disease monitoring in the SLE cohort was undertaken with serial British Isles Lupus Assessment Group (BILAG) scoring. Correlations between specific lipid/anti-lipid responses were investigated as disease activity developed from active flares to quiescent during a follow up period. We report a significant negative correlation between anti-lipid antibodies for 24S-hydroxycholesterol, cardiolipin and phosphatidylserine with SLE disease activity. Taken together, these data suggest that lipid autoantigens represent a new family of biomarkers that can be employed to monitor disease activity plus the efficacy of therapeutic intervention in SLE. PMID:23409013

Jovanovi?, Vojislav; Abdul Aziz, Nurhuda; Lim, Yan Ting; Ng Ai Poh, Amanda; Jin Hui Chan, Sherlynn; Ho Xin Pei, Eliza; Lew, Fei Chuin; Shui, Guanghou; Jenner, Andrew M.; Bowen, Li; McKinney, Eoin F.; Lyons, Paul A.; Kemeny, Michael D.; Smith, Kenneth G. C.; Wenk, Markus R.; MacAry, Paul A.

2013-01-01

228

Lipid Feeding and Milk Fat Depression.  

PubMed

Diets fed to cattle contain mostly unsaturated fatty acids supplied in grains and forages, by-products, and fat supplements. Lipid intake by dairy cattle must be restricted to prevent alterations of microbial populations in the rumen that can negatively affect milk yield. Unsaturated fatty acids consumed by cattle are extensively metabolized through biohydrogenation, intermediates of which include conjugated linoleic acid (CLA) and trans-monoenoic acid isomers. Three specific CLA intermediates of biohydrogenation have been shown to cause milk fat depression in dairy cattle through coordinated suppression of mammary lipogenic genes by a transcription factor that is a central regulator of lipid synthesis. PMID:25239061

Jenkins, Thomas C; Harvatine, Kevin J

2014-11-01

229

Rupture of lipid vesicles near solid surfaces  

NASA Astrophysics Data System (ADS)

The behavior of lipid vesicles near solid surfaces, despite its scientific and technological significance, is poorly understood. By simultaneously taking into account (i) the dynamics of spontaneous pore opening and closing in surface bound vesicles; (ii) their volume loss via leakage through the pores; (iii) and the propagation of their contact line, we have developed a simple model that can fully describe the detailed mechanism of and provide the necessary conditions for the rupture of vesicles and the subsequent formation of supported lipid bilayers. The predictions of the model are in qualitative agreement with many of the experimental observations.

Takáts-Nyeste, Annamária; Derényi, Imre

2014-11-01

230

[Lipids in the diet and atherosclerosis].  

PubMed

Description of the main metabolic methods of different lipoproteins in relation to transportation of both exogenous lipids and endogenous lipids, with special reference to the regulation of synthesis and the destination of colesterol. An analysis was then made of the influence of dietetic colesterol on the different lipoproteins, and that of fatty acids. An evaluation was made of its possible influence on the pathogeny of the atheroma plate. Finally, an alternative unified diet was proposed as a main dietetic guide, both in prevention and therapy. PMID:2132763

Fauré Nogueras, E

1990-01-01

231

SERUM LIPID PROFILE IN SUICIDE ATTEMPTERS  

PubMed Central

Practical difficulties associated with assessment of central parameters necessitates the development of peripheral markers of suicidal risk. Recent research suggest that serum lipid profile may be a useful indicator of suicidal behaviour. Serum lipid profiles of forty suicide attempters were compared with forty age, sex and BMI matched controls. Total serum cholesterol, serum Triglyceride, LDL levels and HDL levels were found to be lower in suicide attempters but were not statistically significant. Statistically significant negative con-elation was seen between risk-rescue score and above mentioned parameters. No statitically significant difference was observed when various diagnostic break-up groups of patients were compared. PMID:21430801

Verma, Sandeep; Trivedi, J.K.; Singh, H.; Dalal, P.K.; Asthana, O.P.; Srivastava, J.S.; Mishra, Rakesh; Ramakant; Sinha, P.K.

1999-01-01

232

Lipid analysis of a ground sloth coprolite  

NASA Astrophysics Data System (ADS)

Coprolites can provide detailed information about the nutritional habits and digestive processes of the animals that produced them and may also yield information about the palaeoenvironment in which the animal existed. To test the utility of the lipid biomarker approach to coprolite analysis, lipids were extracted from a coprolite of the Pleistocene ground sloth Nothrotheriops shastensis. Gas chromatography/mass spectrometry results revealed a dominant spiroketal sapogenin component identified, using nuclear magnetic resonance spectroscopy, as epismilagenin. The dominance of epismilagenin is probably due to ingestion of Yucca spp. and Agave spp., which is consistent with previous studies on the diet of this species.

Gill, Fiona L.; Crump, Matthew P.; Schouten, Remmert; Bull, Ian D.

2009-09-01

233

Salt modulates the stability and lipid binding affinity of the adipocyte lipid-binding proteins  

NASA Technical Reports Server (NTRS)

Adipocyte lipid-binding protein (ALBP or aP2) is an intracellular fatty acid-binding protein that is found in adipocytes and macrophages and binds a large variety of intracellular lipids with high affinity. Although intracellular lipids are frequently charged, biochemical studies of lipid-binding proteins and their interactions often focus most heavily on the hydrophobic aspects of these proteins and their interactions. In this study, we have characterized the effects of KCl on the stability and lipid binding properties of ALBP. We find that added salt dramatically stabilizes ALBP, increasing its Delta G of unfolding by 3-5 kcal/mol. At 37 degrees C salt can more than double the stability of the protein. At the same time, salt inhibits the binding of the fluorescent lipid 1-anilinonaphthalene-8-sulfonate (ANS) to the protein and induces direct displacement of the lipid from the protein. Thermodynamic linkage analysis of the salt inhibition of ANS binding shows a nearly 1:1 reciprocal linkage: i.e. one ion is released from ALBP when ANS binds, and vice versa. Kinetic experiments show that salt reduces the rate of association between ANS and ALBP while simultaneously increasing the dissociation rate of ANS from the protein. We depict and discuss the thermodynamic linkages among stability, lipid binding, and salt effects for ALBP, including the use of these linkages to calculate the affinity of ANS for the denatured state of ALBP and its dependence on salt concentration. We also discuss the potential molecular origins and potential intracellular consequences of the demonstrated salt linkages to stability and lipid binding in ALBP.

Schoeffler, Allyn J.; Ruiz, Carmen R.; Joubert, Allison M.; Yang, Xuemei; LiCata, Vince J.

2003-01-01

234

Investigating lipid-lipid and lipid-protein interactions in model membranes by ToF-SIMS  

NASA Astrophysics Data System (ADS)

With the chemical imaging capability of ToF-SIMS, biological molecules are identified and localized in membranes without any chemical labels. We have developed a model membrane system made with supported Langmuir-Blodgett (LB) monolayers. This simplified model can be used with different combinations of molecules to form a membrane, and thus represents a bottom-up approach to study individual lipid-lipid or lipid-protein interactions. We have used ternary mixtures of sphingomyelin (SM), phosphatidylcholine (PC), and cholesterol (CH) in the model membrane to study the mechanism of domain formation and interactions between phospholipids and cholesterol. Domain structures are observed only when the acyl chain saturation is different for SM and PC in the mixture. The saturated lipid, whether it is SM or PC, is found to be localized with cholesterol, while the unsaturated one is excluded from the domain area. More complicated model membranes which involve a functional membrane protein glycophorin are also investigated and different membrane properties are observed compared to the systems without glycophorin.

Zheng, L.; McQuaw, C. M.; Baker, M. J.; Lockyer, N. P.; Vickerman, J. C.; Ewing, A. G.; Winograd, N.

2008-12-01

235

An ER protein functionally couples neutral lipid metabolism on lipid droplets to membrane lipid synthesis in the ER  

PubMed Central

Eukaryotic cells store neutral lipids, such as triacylglycerol (TAG), in lipid droplets (LDs). Here, we have addressed how LDs are functionally linked to the endoplasmic reticulum (ER). We show in S. cerevisiae that LD growth is sustained by LD-localized enzymes. When LDs grow in early stationary phase, the diacylglycerol acyl-transferase Dga1p moves from the ER to LDs and is responsible for all TAG synthesis from diacylglycerol (DAG). During LD breakdown in early exponential phase, an ER membrane protein, Ice2p, facilitates TAG utilization for membrane-lipid synthesis. Ice2p has a cytosolic domain with affinity for LDs and is required for the efficient utilization of LD-derived DAG in the ER. Ice2p breaks a futile cycle on LDs between TAG-degradation and -synthesis, promoting the rapid re-localization of Dga1p to the ER. Our results show that Ice2p functionally links LDs with the ER, and explain how cells switch neutral lipid metabolism from storage to consumption. PMID:24373967

Markgraf, Daniel F.; Klemm, Robin W.; Junker, Mirco; Hannibal-Bach, Hans K.; Ejsing, Christer S.; Rapoport, Tom A.

2014-01-01

236

A Lipid E-MAP Identifies Ubx2 as a Critical Regulator of Lipid Saturation and Lipid Bilayer Stress  

PubMed Central

SUMMARY Biological membranes are complex, and the mechanisms underlying their homeostasis are incompletely understood. Here, we present a quantitative genetic interaction map (E-MAP) focused on various aspects of lipid biology, including lipid metabolism, sorting, and trafficking. This E-MAP contains ~250,000 negative and positive genetic interaction scores and identifies a molecular crosstalk of protein quality control pathways with lipid bilayer homeostasis. Ubx2p, a component of the endoplasmic-reticulum-associated degradation pathway, surfaces as a key upstream regulator of the essential fatty acid (FA) desaturase Ole1p. Loss of Ubx2p affects the transcriptional control of OLE1, resulting in impaired FA desaturation and a severe shift toward more saturated membrane lipids. Both the induction of the unfolded protein response and aberrant nuclear membrane morphologies observed in cells lacking UBX2 are suppressed by the supplementation of unsaturated FAs. Our results point toward the existence of dedicated bilayer stress responses for membrane homeostasis. PMID:23891562

Surma, Michal A.; Klose, Christian; Peng, Debby; Shales, Michael; Mrejen, Caroline; Stefanko, Adam; Braberg, Hannes; Gordon, David E.; Vorkel, Daniela; Ejsing, Christer S.; Farese, Robert; Simons, Kai; Krogan, Nevan J.; Ernst, Robert

2013-01-01

237

An ER protein functionally couples neutral lipid metabolism on lipid droplets to membrane lipid synthesis in the ER.  

PubMed

Eukaryotic cells store neutral lipids such as triacylglycerol (TAG) in lipid droplets (LDs). Here, we have addressed how LDs are functionally linked to the endoplasmic reticulum (ER). We show that, in S. cerevisiae, LD growth is sustained by LD-localized enzymes. When LDs grow in early stationary phase, the diacylglycerol acyl-transferase Dga1p moves from the ER to LDs and is responsible for all TAG synthesis from diacylglycerol (DAG). During LD breakdown in early exponential phase, an ER membrane protein (Ice2p) facilitates TAG utilization for membrane-lipid synthesis. Ice2p has a cytosolic domain with affinity for LDs and is required for the efficient utilization of LD-derived DAG in the ER. Ice2p breaks a futile cycle on LDs between TAG degradation and synthesis, promoting the rapid relocalization of Dga1p to the ER. Our results show that Ice2p functionally links LDs with the ER and explain how cells switch neutral lipid metabolism from storage to consumption. PMID:24373967

Markgraf, Daniel F; Klemm, Robin W; Junker, Mirco; Hannibal-Bach, Hans K; Ejsing, Christer S; Rapoport, Tom A

2014-01-16

238

Skeletal muscle lipid flux: running water carries no poison.  

PubMed

Lipids are the most abundant organic constituents in many humans. The rise in obesity prevalence has prompted a need for a more refined understanding of the effects of lipid molecules on cell physiology. In skeletal muscle, deposition of lipids can be associated with insulin resistance that contributes to the development of diabetes. Here, we review the evidence that muscle cells are equipped with the molecular machinery to convert and sequester lipid molecules, thus rendering them harmless. Induction of mitochondrial and lipogenic flux in the setting of elevated lipid deposition can protect muscle from lipid-induced "poisoning" of the cellular machinery. Lipid flux may also be directed toward the synthesis of ligands for nuclear receptors, further enhancing the capacity of muscle for lipid metabolism to promote favorable physiology. Exploiting these mechanisms may have implications for the treatment of obesity-related diseases. PMID:21558546

Funai, Katsuhiko; Semenkovich, Clay F

2011-08-01

239

Skeletal muscle lipid flux: running water carries no poison  

PubMed Central

Lipids are the most abundant organic constituents in many humans. The rise in obesity prevalence has prompted a need for a more refined understanding of the effects of lipid molecules on cell physiology. In skeletal muscle, deposition of lipids can be associated with insulin resistance that contributes to the development of diabetes. Here, we review the evidence that muscle cells are equipped with the molecular machinery to convert and sequester lipid molecules, thus rendering them harmless. Induction of mitochondrial and lipogenic flux in the setting of elevated lipid deposition can protect muscle from lipid-induced “poisoning” of the cellular machinery. Lipid flux may also be directed toward the synthesis of ligands for nuclear receptors, further enhancing the capacity of muscle for lipid metabolism to promote favorable physiology. Exploiting these mechanisms may have implications for the treatment of obesity-related diseases. PMID:21558546

Funai, Katsuhiko

2011-01-01

240

Comparative lipid composition of heterotrophically and autotrophically grown Sulfolobus acidocaldarius.  

PubMed Central

Complex lipids from the thermoacidophilic facultative autotroph Sulfolobus acidocaldarius, as well as a strictly autotrophic isolate, were compared between cells grown on yeast extract and elemental sulfur. Lipids from both organisms grown autotrophically were nearly identical. Each contained about 15% neutral lipids, 35% glycolipids, and 50% acidic lipids. Glycolipids and acidic lipids contained C40H82-76-derived glycerol ether residues. Major glycolipids included the glycerol ether analogues of glucosyl galactosyl diglyceride (5%) and glucosyl polyol diglyceride (75%). Acidic lipids were comprised mainly of the glycerol ether analogues of phosphatidyl inositol (7%), inositolphosphoryl glucosyl polyol diglyceride (72%), and a partially characterized sulfate- and phosphate-containing derivative of glucosyl polyol diglyceride (13%). The lipids from cells grown heterotrophically were similar to those from autotrophically grown cells, except that the partially characterized acidic lipid was absent. In addition, the two glycolipids as well as the respective inositolphosphoryl derivatives were each present in nearly equal proportions. Images PMID:863856

Langworthy, T A

1977-01-01

241

21 CFR 862.1470 - Lipid (total) test system.  

Code of Federal Regulations, 2011 CFR

...in serum and plasma. Lipid (total) measurements are used in the diagnosis and treatment of various diseases involving lipid metabolism and atherosclerosis. (b) Classification. Class I (general controls). The device is exempt from the premarket...

2011-04-01

242

An Introduction to Lipid Analysis in the Cell Biology Laboratory.  

ERIC Educational Resources Information Center

Explains a thin-layer chromatography (TLC) experiment that allows students to study complex mixtures of lipids using small volumes. Uses a water-soluble dye to stain lipids that is fast and safe. (YDS)

Schuh, Timothy J.

2002-01-01

243

Irregular bilayer structure in vesicles prepared from Halobacterium cutirubrum lipids  

NASA Technical Reports Server (NTRS)

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.

Lanyi, J. K.

1974-01-01

244

An emerging role of mTOR in lipid biosynthesis  

E-print Network

Lipid biosynthesis is essential for the maintenance of cellular homeostasis. The lipids produced by cells (glycerolipids, fatty acids, phospholipids, cholesterol, and sphingolipids) are used as an energy source/reserve, ...

Laplante, Mathieu

245

Lipid bilayer and cytoskeletal interactions in a red blood cell  

E-print Network

We study the biomechanical interactions between the lipid bilayer and the cytoskeleton in a red blood cell (RBC) by developing a general framework for mesoscopic simulations. We treated the lipid bilayer and the cytoskeleton ...

Peng, Zhangli

246

Lipidomics: quest for molecular lipid biomarkers in cardiovascular disease.  

PubMed

Lipidomics is the comprehensive analysis of molecular lipid species, including their quantitation and metabolic pathways. The huge diversity of native lipids and their modifications make lipidomic analyses challenging. The method of choice for sensitive detection and quantitation of molecular lipid species is mass spectrometry, either by direct infusion (shotgun lipidomics) or coupled with liquid chromatography. Although shotgun lipidomics allows for high-throughput analysis, low-abundant lipid species are not detected. Previous separation of lipid species by liquid chromatography increases ionization efficiency and is better suited for quantifying low abundant and isomeric lipid species. In this review, we will discuss the potential of lipidomics for cardiovascular research. To date, cardiovascular research predominantly focuses on the role of lipid classes rather than molecular entities. An in-depth knowledge about the molecular lipid species that contribute to the pathophysiology of cardiovascular diseases may provide better biomarkers and novel therapeutic targets for cardiovascular disease. PMID:25516624

Hinterwirth, Helmut; Stegemann, Christin; Mayr, Manuel

2014-12-01

247

Turning the spotlight on protein-lipid interactions in cells  

PubMed Central

Protein function is largely dependent on coordinated and dynamic interactions of the protein with biomolecules including other proteins, nucleic acids and lipids. While powerful methods for global profiling of protein-protein and protein-nucleic acid interactions are available, proteome-wide mapping of protein-lipid interactions is still challenging and rarely performed. The emergence of bifunctional lipid probes with photoactivatable and clickable groups offers new chemical tools for globally profiling protein-lipid interactions under cellular contexts. In this review, we summarize recent advances in the development of bifunctional lipid probes for studying protein-lipid interactions. We also highlight how in vivo photocrosslinking reactions contribute to the characterization of lipid-binding proteins and lipidation-mediated protein-protein interactions. PMID:25129056

Peng, Tao; Yuan, Xiaoqiu; Hang, Howard C.

2014-01-01

248

Hydrogen isotope fractionation during lipid biosynthesis by Haloarcula marismortui  

E-print Network

Hydrogen isotope fractionation during lipid biosynthesis by Haloarcula marismortui Sitindra S studied the controls on the fractionation of hydrogen isotopes during lipid biosynthesis by Haloarcula marismortui, a halophilic archaea, in pure culture experiments by varying organic substrate, the hydrogen

249

Tear lipid layer and contact lens comfort: a review.  

PubMed

This review describes the impact of contact lens wear on the tear film lipid layer and how changes in the lipid layer might modulate contact lens-related discomfort. Relevant clinical, functional, and biochemical aspects of the tear film lipid layer are reviewed. Contact lens wear modulates these aspects of the lipid layer, specifically the prelens lipid layer thickness is reduced; tear evaporation rate is increased; tear breakup time is reduced; and the concentration of lipid components such as cholesterol esters, wax esters, and phospholipids varies. The full implications of these changes are unclear; however, there is some evidence that contact lens-related discomfort is associated with a thinner prelens lipid layer, increased lipid degradation, and greater secretory phospholipase A2 activity. Certain fatty acids appear to be associated with maintaining the structural stability of the tear film but their role in retarding tear evaporation and modulating contact lens-related discomfort remains to be elucidated. PMID:23584045

Rohit, Athira; Willcox, Mark; Stapleton, Fiona

2013-05-01

250

CELL BIOLOGY: The Different Hues of Lipid Rafts  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Segregation of lipids and proteins of the plasma membrane into microdomains called lipid rafts is known to be important for many biological processes including signal transduction and pathogen invasion. In his Perspective, van Meer explains new findings (Zacharias et al.) that reveal how lipid moieties attached to proteins instruct the proteins to move into different types of lipid rafts.

Gerrit van Meer (Utrecht University;Department of Membrane Enzymology, CBLE, Institute of Biomembranes)

2002-05-03

251

Lipid-based Nanoparticles for Nucleic Acid Delivery  

Microsoft Academic Search

Abstract  Lipid-based colloidal particles have been extensively studied as systemic gene delivery carriers. The topic that we would\\u000a like to emphasize is the formulation\\/assembly of lipid-based nanoparticles (NP) with diameter under 100 nm for delivering\\u000a nucleic acid in vivo. NP are different from cationic lipid–nucleic acid complexes (lipoplexes) and are vesicles composed of lipids and encapsulated\\u000a nucleic acids with a diameter less

Weijun Li; Francis C. Szoka Jr

2007-01-01

252

Lipid composition of positively buoyant eggs of reef building corals  

Microsoft Academic Search

Lipid composition of the eggs of three reef building corals, Acropora millepora, A. tenuis and Montipora digitata, were determined. Sixty to 70% of the egg dry weight was lipid, which consisted of wax esters (69.5–81.8%), triacylglycerols (1.1–8.4%) and polar lipids c\\/mainly phospholipids (11.9–13.2%). Montipora digitata also contained some polar lipids typical of the thylakoid membrane in chloroplasts, probably due to

Iakayuki Arai; Misako Kato; Andrew Heyward; Yutaka Ikeda; Tokio Iizuka; Tadashi Maruyama

1993-01-01

253

Density and viscosity of lipids under pressure  

Technology Transfer Automated Retrieval System (TEKTRAN)

There is a lack of data for the viscosity of lipids under pressure. The current report is a part of the effort to fill this gap. The viscosity, density, and elastohydrodynamic film thicknesses of vegetable oil (HOSuO) were investigated. Pressure–viscosity coefficients (PVC) of HOSuO at different tem...

254

The organization of melatonin in lipid membranes.  

PubMed

Melatonin is a hormone that has been shown to have protective effects in several diseases that are associated with cholesterol dysregulation, including cardiovascular disease, Alzheimer's disease, and certain types of cancers. We studied the interaction of melatonin with model membranes made of dimyristoylphosphatidylcholine (DMPC) at melatonin concentrations ranging from 0.5mol% to 30mol%. From 2-dimensional X-ray diffraction measurements, we find that melatonin induces a re-ordering of the lipid membrane that is strongly dependent on the melatonin concentration. At low melatonin concentrations, we observe the presence of melatonin-enriched patches in the membrane, which are significantly thinner than the lipid bilayer. The melatonin molecules were found to align parallel to the lipid tails in these patches. At high melatonin concentrations of 30mol%, we observe a highly ordered melatonin structure that is uniform throughout the membrane, where the melatonin molecules align parallel to the bilayers and one melatonin molecule associates with 2 lipid molecules. Understanding the organization and interactions of melatonin in membranes, and how these are dependent on the concentration, may shed light into its anti-amyloidogenic, antioxidative and photoprotective properties and help develop a structural basis for these properties. PMID:25602914

Dies, Hannah; Cheung, Bonnie; Tang, Jennifer; Rheinstädter, Maikel C

2015-04-01

255

LIPID BIOMARKER ANALYSIS OF MARINE DINOFLAGELLATES  

EPA Science Inventory

Many marine eukaryotic algae have been shown to possess characteristic chemotaxonomic lipid biomarkers. Dinoflagellates in particular are often characterized by the presence of sterols and pigments that are rarely found in other classes of algae. To evaluate the utility of chemic...

256

Lipid Injectable Emulsions: Pharmacopeial and Safety Issues  

Microsoft Academic Search

Abstract  Lipid injectable emulsions have been routinely used in patients worldwide for over 40 years as a nutritional supplement in patients requiring parenteral nutrition. They can be given as a separate infusion or added into total parenteral nutrition admixtures. Despite such broad use, no pharmacopeial standards exist with respect to the optimal pharmaceutical characteristics of the formulation. Several attempts to establish

David F. Driscoll

2006-01-01

257

Lipids in innate anti-viral defense  

PubMed Central

Summary It is becoming apparent that infections by a major class of viruses, those with envelopes, can be inhibited during their entry at the step of fusion with cellular membranes. In this review, we discuss multiple innate immune mechanisms that have evolved to modify the lipid composition of cellular and viral membranes to inhibit virion fusion of enveloped viruses. PMID:24139397

Schoggins, John W.; Randall, Glenn

2013-01-01

258

Structural Study of Lipid-binding Proteins  

E-print Network

crystallography is the main method used to solve protein structure. Based on the protein structure, we used different methods to characterize the protein function of three lipid-binding proteins (LprG, LprA, and gp232), and to identify potent inhibitors against...

Tsai, Han-Chun

2013-08-09

259

Pyrolysis of lipids using various catalysts  

Technology Transfer Automated Retrieval System (TEKTRAN)

A specific pursuit of the thermochemical (combustion, gasification, pyrolysis, and liquefaction) conversion of biomass to energy research effort is the potential of converting lipids to alkanes, petroleum-like fuels and chemicals. Arguments can be made for, and against, the use of agricultural lipi...

260

Engineering lipid bilayer membranes for protein studies.  

PubMed

Lipid membranes regulate the flow of nutrients and communication signaling between cells and protect the sub-cellular structures. Recent attempts to fabricate artificial systems using nanostructures that mimic the physiological properties of natural lipid bilayer membranes (LBM) fused with transmembrane proteins have helped demonstrate the importance of temperature, pH, ionic strength, adsorption behavior, conformational reorientation and surface density in cellular membranes which all affect the incorporation of proteins on solid surfaces. Much of this work is performed on artificial templates made of polymer sponges or porous materials based on alumina, mica, and porous silicon (PSi) surfaces. For example, porous silicon materials have high biocompatibility, biodegradability, and photoluminescence, which allow them to be used both as a support structure for lipid bilayers or a template to measure the electrochemical functionality of living cells grown over the surface as in vivo. The variety of these media, coupled with the complex physiological conditions present in living systems, warrant a summary and prospectus detailing which artificial systems provide the most promise for different biological conditions. This study summarizes the use of electrochemical impedance spectroscopy (EIS) data on artificial biological membranes that are closely matched with previously published biological systems using both black lipid membrane and patch clamp techniques. PMID:24185908

Khan, Muhammad Shuja; Dosoky, Noura Sayed; Williams, John Dalton

2013-01-01

261

Waxes: A Forgotten Topic in Lipid Teaching.  

ERIC Educational Resources Information Center

Reviews the biological importance of the lipids categorized as waxes and describes some of the organic chemistry of these compounds. Presents a short laboratory exercise on the extraction of plant waxes and their analysis by thin layer chromatography. (Author/CCM)

Dominguez, Eva; Heredia, Antonio

1998-01-01

262

Electrostatic interactions across a charged lipid bilayer  

E-print Network

We present theoretical work in which the degree of electrostatic coupling across a charged lipid bilayer in aqueous solution is analyzed on the basis of nonlinear Poisson-Boltzmann theory. In particular, we consider the electrostatic interaction of a single, large macroion with the two apposed leaflets of an oppositely charged lipid bilayer where the macroion is allowed to optimize its distance to the membrane. Three regimes are identified: a weak and a high macroion charge regime, separated by a regime of close macroion-membrane contact for intermediate charge densities. The corresponding free energies are used to estimate the degree of electrostatic coupling in a lamellar cationic lipid-DNA complex. That is, we calculate to what extent the one-dimensional DNA arrays in a sandwich-like lipoplex interact across the cationic membranes. We find that, in spite of the low dielectric constant inside a lipid membranes, there can be a significant electrostatic contribution to the experimentally observed cross-bilayer orientational ordering of the DNA arrays. Our approximate analytical model is complemented and supported by numerical calculations of the electrostatic potentials and free energies of the lamellar lipoplex geometry. To this end, we solve the nonlinear Poisson-Boltzmann equation within a unit cell of the lamellar lipoplex using a new lattice Boltzmann method.

Alexander J. Wagner; Sylvio May

2006-07-27

263

Lipid Transfer Proteins and Allergy to Oranges  

Microsoft Academic Search

Background: Lipid transfer proteins (LTPs) are relevant fruit allergens, recently proposed as model plant food allergens. No citrus fruit allergen has been characterized to date. We sought to identify and isolate citrus fruit LTPs and to explore their relevance in orange allergy. Methods: Twenty-seven patients, showing mainly oral allergy syndrome after orange ingestion, as well as positive prick responses and

Oussama Ahrazem; M. Dolores Ibáñez; Gema López-Torrejón; Rosa Sánchez-Monge; Joaquin Sastre; Manuel Lombardero; Domingo Barber; Gabriel Salcedo

2005-01-01

264

Review article Lipids in monogastric animal meat  

E-print Network

Review article Lipids in monogastric animal meat Jacques MOUROTa*, Dominique HERMIERb a Unité Mixte; accepted 9 February 2001) Abstract -- Meat from monogastric animals, essentially pigs and poultry, is from afar the most consumed of all meats. Meat products from every species have their own characteristics

Paris-Sud XI, Université de

265

NUTRIGENETICS, PLASMA LIPIDS AND CARDIOVASCULAR RISK  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cardiovascular diseases (CVD) result from complex interactions between genetic and environmental factors. The evidence supports that gene-environment interactions modulate plasma lipid concentrations and potentially CVD risk. Several genes [i.e., APOA1, APOA4, APOE, and LIPC] are providing proof-of-...

266

Lipid accumulation in dysferlin-deficient muscles.  

PubMed

Dysferlin is a membrane associated protein involved in vesicle trafficking and fusion. Defects in dysferlin result in limb-girdle muscular dystrophy type 2B and Miyoshi myopathy in humans and myopathy in A/J(dys-/-) and BLAJ mice, but the pathomechanism of the myopathy is not understood. Oil Red O staining showed many lipid droplets within the psoas and quadriceps muscles of dysferlin-deficient A/J(dys-/-) mice aged 8 and 12 months, and lipid droplets were also conspicuous within human myofibers from patients with dysferlinopathy (but not other myopathies). Electron microscopy of 8-month-old A/J(dys-/-) psoas muscles confirmed lipid droplets within myofibers and showed disturbed architecture of myofibers. In addition, the presence of many adipocytes was confirmed, and a possible role for dysferlin in adipocytes is suggested. Increased expression of mRNA for a gene involved in early lipogenesis, CCAAT/enhancer binding protein-?, in 3-month-old A/J(dys-/-) quadriceps (before marked histopathology is evident), indicates early induction of lipogenesis/adipogenesis within dysferlin-deficient muscles. Similar results were seen for dysferlin-deficient BLAJ mice. These novel observations of conspicuous intermyofibrillar lipid and progressive adipocyte replacement in dysferlin-deficient muscles present a new focus for investigating the mechanisms that result in the progressive decline of muscle function in dysferlinopathies. PMID:24685690

Grounds, Miranda D; Terrill, Jessica R; Radley-Crabb, Hannah G; Robertson, Terry; Papadimitriou, John; Spuler, Simone; Shavlakadze, Tea

2014-06-01

267

Lysosomal exocytosis and lipid storage disorders.  

PubMed

Lysosomes are acidic compartments in mammalian cells that are primarily responsible for the breakdown of endocytic and autophagic substrates such as membranes, proteins, and lipids into their basic building blocks. Lysosomal storage diseases (LSDs) are a group of metabolic disorders caused by genetic mutations in lysosomal hydrolases required for catabolic degradation, mutations in lysosomal membrane proteins important for catabolite export or membrane trafficking, or mutations in nonlysosomal proteins indirectly affecting these lysosomal functions. A hallmark feature of LSDs is the primary and secondary excessive accumulation of undigested lipids in the lysosome, which causes lysosomal dysfunction and cell death, and subsequently pathological symptoms in various tissues and organs. There are more than 60 types of LSDs, but an effective therapeutic strategy is still lacking for most of them. Several recent in vitro and in vivo studies suggest that induction of lysosomal exocytosis could effectively reduce the accumulation of the storage materials. Meanwhile, the molecular machinery and regulatory mechanisms for lysosomal exocytosis are beginning to be revealed. In this paper, we first discuss these recent developments with the focus on the functional interactions between lipid storage and lysosomal exocytosis. We then discuss whether lysosomal exocytosis can be manipulated to correct lysosomal and cellular dysfunction caused by excessive lipid storage, providing a potentially general therapeutic approach for LSDs. PMID:24668941

Samie, Mohammad Ali; Xu, Haoxing

2014-03-25

268

Lipid droplet targeting domains of adipophilin  

Microsoft Academic Search

Adipophilin (ADPH), a prominent protein com- ponent of lipid storage droplets (LSDs), is postulated to be necessary for the formation and cellular function of these structures. The presence of significant sequence similarities within an ? 100 amino acid region of the N-terminal por- tions of ADPH and related LSD binding proteins, perilipin and TIP47, has implicated this region, known as

James L. McManaman; William Zabaronick; Jerome Schaack; David J. Orlicky

2003-01-01

269

Nutrigenetics, plasma lipids, and cardiovascular risk  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cardiovascular disease (CVD) results from complex interactions between genetic and environmental factors. The evidence supports that gene-environment interactions modulate plasma lipid concentrations and potentially CVD risk. Several genes (eg, apolipoprotein A-I and A-IV, apolipoprotein E, and he...

270

Lipid mono- and bilayer supported on polymer films: composite polymer-lipid films on solid substrates.  

PubMed Central

We report the deposition of lipid monolayers and bilayers on polyacrylamide films deposited by radical chain reaction onto solid substrates in aqueous solutions. Polymer films of various degrees of monomer density and cross-linking are prepared. Lateral diffusion and fluorescent probe permeation measurements yield insight into the continuity of the lipid layers and show that monolayers exposed to air are much less sensitive towards polymer heterogeneities than bilayers below water, which is explained in terms of the wetting laws. The diffusion studies of lipid and lipopeptide probes yield absolute values of the frictional coefficients between the lipid layer and the polymer films and allow one to estimate the surface viscosity of the polymer film. The potential applications of supported membranes on soft thin polymer films for the preparation of biofunctionalized surfaces or biocompatible receptive surfaces for biosensors are discussed. Images FIGURE 2 FIGURE 3 FIGURE 4 PMID:7918990

Kühner, M; Tampé, R; Sackmann, E

1994-01-01

271

High melting lipid based approach for drug delivery: solid lipid nanoparticles.  

PubMed

Poor solubility of newly developed drug molecules is the main problem in recent drug discovery research, so novel drug delivery approaches are being used to deliver these molecular entities for pharmacological action. Colloidal carriers (emulsion, suspensions, liposomes, polymer nanoparticles and solid lipid nanoparticles) have been used to administer poorly soluble drugs, but solid lipid nanoparticles are found to be the most reliable carriers for this type of drugs due to its advantages over other carriers. Solid lipid nanoparticles have the potential to solve the drug delivery problems with safe excipients used in its formulation. In this review all the aspects of solid lipid nanoparticles production, stability, characterization, differentiation based on route, preservation and storage have been discussed. PMID:23498204

Kumar, Sacheen; Randhawa, Jaspreet Kaur

2013-05-01

272

Atomistic Study of Lipid Membranes Containing Chloroform: Looking for a Lipid-Mediated Mechanism of Anesthesia  

PubMed Central

The molecular mechanism of general anesthesia is still a controversial issue. Direct effect by linking of anesthetics to proteins and indirect action on the lipid membrane properties are the two hypotheses in conflict. Atomistic simulations of different lipid membranes subjected to the effect of small volatile organohalogen compounds are used to explore plausible lipid-mediated mechanisms. Simulations of homogeneous membranes reveal that electrostatic potential and lateral pressure transversal profiles are affected differently by chloroform (anesthetic) and carbon tetrachloride (non-anesthetic). Simulations of structured membranes that combine ordered and disordered regions show that chloroform molecules accumulate preferentially in highly disordered lipid domains, suggesting that the combination of both lateral and transversal partitioning of chloroform in the cell membrane could be responsible of its anesthetic action. PMID:23300982

Reigada, Ramon

2013-01-01

273

Selenium induced lipid peroxidation in heart tissues of chick embryos  

Microsoft Academic Search

During the past three decades research has been carried out to elucidate the role of free radicals and reactive oxygen species play in various pathophysiological processes (Fridovich 1986; Slater et al 1987). Membranes of subcellular organelles contain relatively high concentrations of polyunsaturated lipids as well as hemoproteins which are strong catalysts of lipid peroxidation. Lipid peroxides (LPO) destroy membrane integrity

K. Padmaja; B. V. Somasekharaiah; A. R. K. Prasad

1993-01-01

274

Control of Lipid Metabolism by Tachykinin in Drosophila Graphical Abstract  

E-print Network

Report Control of Lipid Metabolism by Tachykinin in Drosophila Graphical Abstract Highlights TK EE- ological roles for enteroendocrine cells (EEs) and gut hormones in intestinal lipid metabolism regulation.08.060 #12;Cell Reports Report Control of Lipid Metabolism by Tachykinin in Drosophila Wei Song,1,2,* Jan A

Perrimon, Norbert

275

Epoxide hydrolases: their roles and interactions with lipid metabolism  

E-print Network

Review Epoxide hydrolases: their roles and interactions with lipid metabolism John W. Newman present in all living organisms, which transform epoxide con- taining lipids by the addition of water. In plants and animals, many of these lipid substrates have potent biologically activities, such as host

Hammock, Bruce D.

276

Cytochrome P450-Dependent Lipid Metabolism in Preovulatory Follicles  

E-print Network

Cytochrome P450-Dependent Lipid Metabolism in Preovulatory Follicles J. W. NEWMAN, J. E. STOK, J. D. However, CYP-dependent lipid metabolism has not been characterized with respect to follicular matura- tion, and concentra- tions of epoxy, hydroxy, and dihydroxy lipids were measured by liquid chromatography tandem mass

Hammock, Bruce D.

277

Original article Relationship between lipid parameters and the  

E-print Network

in the heart : a study on rats fed low erucic acid rapeseed oil G. Rocquelin P. Juaneda P.O. Astorg A. Grynberg Wistar SPF rats were fed a diet containing low erucic acid rapeseed (LEAR) oil (15% by weight) as the only source of lipids for 18 wk. Lipid parameters (fatty acid composition and contents of lipid classes

Paris-Sud XI, Université de

278

Epidermal lipid in several cetacean species: ultrastructural observations  

Microsoft Academic Search

The ultrastructure of the skin of four cetacean species, bottlenose dolphin (Tursiops truncatus) long-finned pilot whale (Globicephala melaena), humpback whale (Megaptera novaeangliae), and fin whale (Balaenoptera physalus) was investigated with particular reference to epidermal lipid. It has already been established that massive lipid reservoirs exist in whales, that the biochemical structures of cetacean lipids are unique, and that unusual intracellular

Carl J. Pfeiffer; Flynn M. Jones

1993-01-01

279

Chemical Changes in Lipids Produced by Thermal Processing.  

ERIC Educational Resources Information Center

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)

Nawar, Wassef W.

1984-01-01

280

Solid lipid nanoparticles for targeted brain drug delivery  

Microsoft Academic Search

The present review discusses the potential use of solid lipid nanoparticles for brain drug targeting purposes. The state of the art on surfactant-coated poly(alkylcyanoacrylate) nanoparticles specifically designed for brain targeting is given by emphasizing the transfer of this technology to solid lipid matrices. The available literature on solid lipid nanoparticles and related carriers for brain drug targeting is revised as

Paolo Blasi; Stefano Giovagnoli; Aurélie Schoubben; Maurizio Ricci; Carlo Rossi

2007-01-01

281

Lipid composition of an iridescent virus type 6 (CIV)  

Microsoft Academic Search

Summary The Chilo Iridescent Virus (CIV) is a lipid-containing virus propagatedin vitro inChoristoneura fumiferana cell cultures. We have analysed the individual lipids of the viral membrane which appeared interesting in their relative amounts and mainly in the high proportion of phosphatidylinositol. This fraction represented about 27 per cent of the phospholipid extract. The lipid composition of the viral membrane was

Nicole Balange-Orange; G. Devauchelle

1982-01-01

282

Alteration of lipid metabolism in cells infected with human cytomegalovirus  

Microsoft Academic Search

The human cytomegalovirus (HCMV) envelope contains 12 virus-encoded glycoproteins and glycoprotein complexes but the lipid composition of the envelope has not been clearly defined. Given the specificity of the interactions between integral membrane proteins and lipids, it is likely that the lipid content of the virion envelope is regulated during infection. In an effort to determine the effects of HCMV

Veronica Sanchez; Jennifer J. Dong

2010-01-01

283

Final Report: 17th international Symposium on Plant Lipids  

SciTech Connect

This meeting covered several emerging areas in the plant lipid field such as the biosynthesis of cuticle components, interorganelle lipid trafficking, the regulation of lipid homeostasis, and the utilization of algal models. Stimulating new insights were provided not only based on research reports based on plant models, but also due to several excellent talks by experts from the yeast field.

Christoph Benning

2007-03-07

284

Heterotrophic growth and lipid production of Chlorella protothecoides on glycerol.  

PubMed

During the production of biodiesel, a significant amount of glycerol is generated which currently has little commercial value. A study on the growth and lipid production of Chlorella protothecoides using glycerol as the carbon source was performed to demonstrate the utility of recycling crude glycerol created during biodiesel production. Glycerol was examined as both the sole carbon source and in combination with glucose. Algae cultures grown on only glycerol in shake flasks showed a specific growth rate and final lipid yield of 0.1/h and 0.31 g lipid/g substrate, respectively. The values were similar to those observed on pure glucose, 0.096/h and 0.24 g lipid/g substrate. When the media contained a mixture of glycerol and glucose, simultaneous uptake of the two substrates was observed. Due to the difference in rates of lipid storage, lipid production was 0.077 g lipid/(l h) during growth on glycerol, while growth on glucose had a productivity of 0.096 g lipid/(l h). During growth on the 9:1 mixture of both glucose and glycerol, lipid productivity was 0.098 g lipid/(l h). In order to simulate the use of waste glycerol from biodiesel production the experiments were repeated and similar growth rates, yields, and lipid productivities were achieved. Therefore, we have demonstrated the promise for simultaneous high growth rates and lipid yields of C. protothecoides heterotrophically grown on mixtures of glycerol. PMID:20976474

O'Grady, John; Morgan, John A

2011-01-01

285

Lipid–Drug Interaction and Colligative Properties in Phospholipid Vesicles  

Microsoft Academic Search

Imipramine penetration into the lipid core of a membrane was demonstrated through measurements on lipid monolayers (surface pressure and surface potential). The surface pressure measurements allow us to calculate the intrinsic binding constant (partition coefficient) for the lipid–Imipramine interaction. This latter value is in correct agreement with the results obtained by electrophoretic mobility measurements on liposomes. In addition, it was

S. Banerjee; M. Bennouna; J. Ferreira-Marques; J. M. Ruysschaert; J. Caspers

1999-01-01

286

Lead-revealed lipid organization in human hair  

Microsoft Academic Search

Human hair lipids form a complex mixture of composition close to that of sebum. Part of these lipids appears in an organized state that has been studied by diffraction techniques in the literature. Nevertheless, information on the structure of these lipids remains very scarce due to their low contribution to global hair diffraction pattern. Here we show that appropriate lead

L Bertrand; J Doucet; A Simionovici; G Tsoucaris; P Walter

2003-01-01

287

A Teaching Laboratory for Comprehensive Lipid Characterization from Food Samples  

ERIC Educational Resources Information Center

Traditional and state-of-the-art techniques were combined to probe for various lipid classes from egg yolk and avocado qualitatively and quantitatively. A total lipid extract was isolated using liquid-liquid extraction. An aliquot of the total lipid extract was subjected to transesterification to form volatile fatty acid methyl esters suitable for…

Bendinskas, Kestutis; Weber, Benjamin; Nsouli, Tamara; Nguyen, Hoangvy V.; Joyce, Carolyn; Niri, Vadoud; Jaskolla, Thorsten W.

2014-01-01

288

Intrafamilial Associations of Lipid Profiles and the Role of Nutrition: The Tehran Lipid and Glucose Study  

Microsoft Academic Search

Background: The role of gene and environment in the genesis of abnormal lipid profile is still a controversial issue. Objective: To clarify the importance of certain parental risk factors associated with lipid profiles of children and adolescents. Methods: We conducted this cross-sectional population-based study in district 13 in the east of metropolitan Tehran.One hundred and thirteen eligible families comprising 455

Parvin Mirmiran; Mohammadreza Mirbolooki; Peimaneh Heydarian; Payam Salehi; Fereidoun Azizi

2008-01-01

289

The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids  

Microsoft Academic Search

Lipids were obtained from high potassium (HK) and low potas- sium (LK) sheep red cells by sequential extraction of the erythrocytes with iso- propanol-chloroform, chloroform-methanol-0.1 ~ KC1, and chloroform. The extract contained cholesterol and phospholipid in a molar ratio of 0.8 : 1.0, and less than 1% protein contaminant. Stable thin lipid membranes separating two aqueous compartments were formed from

THOMAS E. ANDREOLI; ANDREW BANGHAM; DANIEL C. TOSTESON

1967-01-01

290

Quercetin Induces Hepatic Lipid Omega-Oxidation and Lowers Serum Lipid Levels in Mice  

PubMed Central

Elevated circulating lipid levels are known risk factors for cardiovascular diseases (CVD). In order to examine the effects of quercetin on lipid metabolism, mice received a mild-high-fat diet without (control) or with supplementation of 0.33% (w/w) quercetin for 12 weeks. Gas chromatography and 1H nuclear magnetic resonance were used to quantitatively measure serum lipid profiles. Whole genome microarray analysis of liver tissue was used to identify possible mechanisms underlying altered circulating lipid levels. Body weight, energy intake and hepatic lipid accumulation did not differ significantly between the quercetin and the control group. In serum of quercetin-fed mice, triglycerides (TG) were decreased with 14% (p<0.001) and total poly unsaturated fatty acids (PUFA) were increased with 13% (p<0.01). Palmitic acid, oleic acid, and linoleic acid were all decreased by 9–15% (p<0.05) in quercetin-fed mice. Both palmitic acid and oleic acid can be oxidized by omega (?)-oxidation. Gene expression profiling showed that quercetin increased hepatic lipid metabolism, especially ?-oxidation. At the gene level, this was reflected by the up-regulation of cytochrome P450 (Cyp) 4a10, Cyp4a14, Cyp4a31 and Acyl-CoA thioesterase 3 (Acot3). Two relevant regulators, cytochrome P450 oxidoreductase (Por, rate limiting for cytochrome P450s) and the transcription factor constitutive androstane receptor (Car; official symbol Nr1i3) were also up-regulated in the quercetin-fed mice. We conclude that quercetin intake increased hepatic lipid ?-oxidation and lowered corresponding circulating lipid levels, which may contribute to potential beneficial effects on CVD. PMID:23359794

Hoek-van den Hil, Elise F.; Keijer, Jaap; Bunschoten, Annelies; Vervoort, Jacques J. M.; Stankova, Barbora; Bekkenkamp, Melissa; Herreman, Laure; Venema, Dini; Hollman, Peter C. H.; Tvrzicka, Eva; Rietjens, Ivonne M. C. M.; van Schothorst, Evert M.

2013-01-01

291

A lipid zipper triggers bacterial invasion.  

PubMed

Glycosphingolipids are important structural constituents of cellular membranes. They are involved in the formation of nanodomains ("lipid rafts"), which serve as important signaling platforms. Invasive bacterial pathogens exploit these signaling domains to trigger actin polymerization for the bending of the plasma membrane and the engulfment of the bacterium--a key process in bacterial uptake. However, it is unknown whether glycosphingolipids directly take part in the membrane invagination process. Here, we demonstrate that a "lipid zipper," which is formed by the interaction between the bacterial surface lectin LecA and its cellular receptor, the glycosphingolipid Gb3, triggers plasma membrane bending during host cell invasion of the bacterium Pseudomonas aeruginosa. In vitro experiments with Gb3-containing giant unilamellar vesicles revealed that LecA/Gb3-mediated lipid zippering was sufficient to achieve complete membrane engulfment of the bacterium. In addition, theoretical modeling elucidated that the adhesion energy of the LecA-Gb3 interaction is adequate to drive the engulfment process. In cellulo experiments demonstrated that inhibition of the LecA/Gb3 lipid zipper by either lecA knockout, Gb3 depletion, or application of soluble sugars that interfere with LecA binding to Gb3 significantly lowered P. aeruginosa uptake by host cells. Of note, membrane engulfment of P. aeruginosa occurred independently of actin polymerization, thus corroborating that lipid zippering alone is sufficient for this crucial first step of bacterial host-cell entry. Our study sheds new light on the impact of glycosphingolipids in the cellular invasion of bacterial pathogens and provides a mechanistic explication of the initial uptake processes. PMID:25136128

Eierhoff, Thorsten; Bastian, Björn; Thuenauer, Roland; Madl, Josef; Audfray, Aymeric; Aigal, Sahaja; Juillot, Samuel; Rydell, Gustaf E; Müller, Stefan; de Bentzmann, Sophie; Imberty, Anne; Fleck, Christian; Römer, Winfried

2014-09-01

292

Hybrid lipid-silica microcapsules engineered by phase coacervation of Pickering emulsions to enhance lipid hydrolysis.  

PubMed

We report on the fabrication of dry hybrid lipid-silica microcapsules for enhanced lipid hydrolysis using Pickering emulsion templates formed by interfacial nanoparticle-emulsifier electrostatic interaction. The microcapsules are produced by controlled precipitation of emulsion droplets by oppositely charged silica nanoparticles at room temperature. Microcapsule formation is driven by the interfacial structure of the initial Pickering emulsion, which is in turn controlled by the nanoparticle to lipid ratio. In the region of charge reversed, precipitated and aggregated droplets, droplet-nanoparticle networks have been identified by freeze-fracture SEM imaging. The microcapsules have diameters in the range 20-50 mum and contain approximately 65% oil distributed within an internal matrix structure composed of a labyrinth of interconnected pores approximately 20-100 nm. Pore distribution and diameters depend on the silica to nanoparticle ratio that in turn determines droplet coating and stability. The microcapsules facilitate enhanced lipid hydrolysis kinetics, i.e. their pseudo first-order rate constant for lipid hydrolysis is approximately 3 times greater than for equivalent submicron lipid droplets. This behaviour is attributed to the increased oil surface area within the microcapsule due to the specific porous structure that causes rapid release of submicron and micron size oil droplets. The simple route for fabrication of porous microcapsule morphologies may present new opportunities for applications in encapsulation, delivery, coatings, and catalysis. PMID:20490395

Simovic, Spomenka; Heard, Peter; Prestidge, Clive A

2010-07-14

293

Polymerized planar suspended lipid bilayers for single ion channel recordings: comparison of several dienoyl lipids.  

PubMed

The stabilization of suspended planar lipid membranes, or black lipid membranes (BLMs), through polymerization of mono- and bis-functionalized dienoyl lipids was investigated. Electrical properties, including capacitance, conductance, and dielectric breakdown voltage, were determined for BLMs composed of mono-DenPC, bis-DenPC, mono-SorbPC, and bis-SorbPC both prior to and following photopolymerization, with diphytanoyl phosphocholine (DPhPC) serving as a control. Poly(lipid) BLMs exhibited significantly longer lifetimes and increased the stability of air-water transfers. BLM stability followed the order bis-DenPC > mono-DenPC ? mono-SorbPC > bis-SorbPC. The conductance of bis-SorbPC BLMs was significantly higher than that of the other lipids, which is attributed to a high density of hydrophilic pores, resulting in relatively unstable membranes. The use of poly(lipid) BLMs as matrices for supporting the activity of an ion channel protein (IC) was explored using ?-hemolysin (?-HL), a model IC. Characteristic i-V plots of ?-HL were maintained following photopolymerization of bis-DenPC, mono-DenPC, and mono-SorbPC, demonstrating the utility of these materials for preparing more durable BLMs for single-channel recordings of reconstituted ICs. PMID:21226498

Heitz, Benjamin A; Xu, Juhua; Jones, Ian W; Keogh, John P; Comi, Troy J; Hall, Henry K; Aspinwall, Craig A; Saavedra, S Scott

2011-03-01

294

Solid lipid nanoparticles of guggul lipid as drug carrier for transdermal drug delivery.  

PubMed

Diclofenac sodium loaded solid lipid nanoparticles (SLNs) were formulated using guggul lipid as major lipid component and analyzed for physical parameters, permeation profile, and anti-inflammatory activity. The SLNs were prepared using melt-emulsion sonication/low temperature-solidification method and characterized for physical parameters, in vitro drug release, and accelerated stability studies, and formulated into gel. Respective gels were compared with a commercial emulgel (CEG) and plain carbopol gel containing drug (CG) for ex vivo and in vivo drug permeation and anti-inflammatory activity. The SLNs were stable with optimum physical parameters. GMS nanoparticle 1 (GMN-1) and stearic acid nanoparticle 1 (SAN-1) gave the highest in vitro drug release. Guggul lipid nanoparticle gel 3 (GLNG-3) showed 104.68 times higher drug content than CEG in receptor fluid. The enhancement ratio of GLNG-3 was 39.43 with respect to CG. GLNG-3 showed almost 8.12 times higher C(max) than CEG at 4 hours. The AUC value of GLNG-3 was 15.28 times higher than the AUC of CEG. GLNG-3 showed edema inhibition up to 69.47% in the first hour. Physicochemical properties of major lipid component govern the properties of SLN. SLN made up of guggul lipid showed good physical properties with acceptable stability. Furthermore, it showed a controlled drug release profile along with a promising permeation profile. PMID:24058913

Gaur, Praveen Kumar; Mishra, Shikha; Purohit, Suresh

2013-01-01

295

Polymerized Planar Suspended Lipid Bilayers for Single Ion Channel Recordings: Comparison of Several Dienoyl Lipids  

PubMed Central

The stabilization of suspended planar lipid membranes, or black lipid membranes (BLMs), through polymerization of mono- and bis-functionalized dienoyl lipids was investigated. Electrical properties, including capacitance, conductance, and dielectric breakdown voltage, were determined for BLMs composed of mono-DenPC, bis-DenPC, mono-SorbPC, and bis-SorbPC both prior to and following photopolymerization, with diphytanoyl phosphocholine (DPhPC) serving as a control. Poly(lipid) BLMs exhibited significantly longer lifetimes and increased the stability to air-water transfers. BLM stability followed the order: bis-DenPC > mono-DenPC ? mono-SorbPC > bis-SorbPC. The conductance of bis-SorbPC BLMs was significantly higher than that of the other lipids, which is attributed to a high density of hydrophilic pores, resulting in relatively unstable membranes. The use of poly(lipid) BLMs as matrices for supporting the activity of an ion channel protein (IC) was explored using ? – hemolysin (?-HL), a model IC. Characteristic i-V plots of ?-HL were maintained following photopolymerization of bis-DenPC, mono-DenPC, and mono-SorbPC, demonstrating the utility of these materials for preparing more durable BLMs for single channel recordings of reconstituted ICs. PMID:21226498

Heitz, Benjamin A.; Xu, Juhua; Jones, Ian W.; Keogh, John P.; Comi, Troy J.; Hall, Henry K.; Aspinwall, Craig A.; Saavedra, S. Scott

2011-01-01

296

Lipid domains control myelin basic protein adsorption and membrane interactions between model myelin lipid bilayers  

PubMed Central

The surface forces apparatus and atomic force microscope were used to study the effects of lipid composition and concentrations of myelin basic protein (MBP) on the structure of model lipid bilayers, as well as the interaction forces and adhesion between them. The lipid bilayers had a lipid composition characteristic of the cytoplasmic leaflets of myelin from “normal” (healthy) and “disease-like” [experimental allergic encephalomyelitis (EAE)] animals. They showed significant differences in the adsorption mechanism of MBP. MBP adsorbs on normal bilayers to form a compact film (3–4 nm) with strong intermembrane adhesion (?0.36 mJ/m2), in contrast to its formation of thicker (7–8 nm) swelled films with weaker intermembrane adhesion (?0.13 mJ/m2) on EAE bilayers. MBP preferentially adsorbs to liquid-disordered submicron domains within the lipid membranes, attributed to hydrophobic attractions. These results show a direct connection between the lipid composition of membranes and membrane–protein adsorption mechanisms that affects intermembrane spacing and adhesion and has direct implications for demyelinating diseases. PMID:24516125

Lee, Dong Woog; Banquy, Xavier; Kristiansen, Kai; Kaufman, Yair; Boggs, Joan M.; Israelachvili, Jacob N.

2014-01-01

297

Multiscale structures of lipids in foods & Fatty acid metabolism Revised version submitted to Progress in Lipid Research March 2013  

E-print Network

« Multiscale structures of lipids in foods & Fatty acid metabolism » Revised version submitted fatty acid bioavailability and lipid metabolism M.C. Michalski,a,b C. Genot,c C. Gayet,d C. Lopez,e F & Fatty acid metabolism » Revised version submitted to Progress in Lipid Research ­ March 2013 2 Abstract

Paris-Sud XI, Université de

298

Computer simulations of phase separation in lipid bilayers and monolayers.  

PubMed

Studying phase coexistence in lipid bilayers and monolayers is important for understanding lipid-lipid interactions underlying lateral organization in biological membranes. Computer simulations follow experimental approaches and use model lipid mixtures of simplified composition. Atomistic simulations give detailed information on the specificity of intermolecular interactions, while coarse-grained simulations achieve large time and length scales and provide a bridge towards state-of-the-art experimental techniques. Computer simulations allow characterizing the structure and composition of domains during phase transformations at Angstrom and picosecond resolution, and bring new insights into phase behavior of lipid membranes. PMID:25331143

Baoukina, Svetlana; Tieleman, D Peter

2015-01-01

299

Lipid Rafts: Keys to Sperm Maturation, Fertilization, and Early Embryogenesis  

PubMed Central

Cell membranes are composed of many different lipids and protein receptors, which are important for regulating intracellular functions and cell signaling. To orchestrate these activities, the cell membrane is compartmentalized into microdomains that are stably or transiently formed. These compartments are called “lipid rafts”. In gamete cells that lack gene transcription, distribution of lipids and proteins on these lipid rafts is focused during changes in their structure and functions such as starting flagella movement and membrane fusion. In this paper, we describe the role of lipid rafts in gamete maturation, fertilization, and early embryogenesis. PMID:21490798

Kawano, Natsuko; Yoshida, Kaoru; Miyado, Kenji; Yoshida, Manabu

2011-01-01

300

Functional lipids and lipoplexes for improved gene delivery  

PubMed Central

Cationic lipids are the most common non-viral vectors used in gene delivery with a few currently being investigated in clinical trials. However, like most other synthetic vectors, these vectors suffer from low transfection efficiencies. Among the various approaches to address this challenge, functional lipids (i.e., lipids responding to a stimuli) offer a myriad of opportunities for basic studies of nucleic acid–lipid interactions and for in vitro and in vivo delivery of nucleic acid for a specific biological/medical application. This manuscript reviews recent advances in pH, redox, and charge-reversal sensitive lipids. PMID:21621581

Zhang, Xiao-Xiang; McIntosh, Thomas J.; Grinstaff, Mark W.

2013-01-01

301

Lipid-Drug Interaction and Colligative Properties in Phospholipid Vesicles.  

PubMed

Imipramine penetration into the lipid core of a membrane was demonstrated through measurements on lipid monolayers (surface pressure and surface potential). The surface pressure measurements allow us to calculate the intrinsic binding constant (partition coefficient) for the lipid-Imipramine interaction. This latter value is in correct agreement with the results obtained by electrophoretic mobility measurements on liposomes. In addition, it was observed that the same mole fraction of "lipid-soluble drug" (Chlorpromazine or Imipramine) incorporated in a given lipidic phase (DPPC) induced the same shift in the transition temperature. Copyright 1999 Academic Press. PMID:10527584

Banerjee; Bennouna; Ferreira-Marques; Ruysschaert; Caspers

1999-11-01

302

Lipid raft: A floating island of death or survival  

SciTech Connect

Lipid rafts are microdomains of the plasma membrane enriched in cholesterol and sphingolipids, and play an important role in the initiation of many pharmacological agent-induced signaling pathways and toxicological effects. The structure of lipid rafts is dynamic, resulting in an ever-changing content of both lipids and proteins. Cholesterol, as a major component of lipid rafts, is critical for the formation and configuration of lipid raft microdomains, which provide signaling platforms capable of activating both pro-apoptotic and anti-apoptotic signaling pathways. A change of cholesterol level can result in lipid raft disruption and activate or deactivate raft-associated proteins, such as death receptor proteins, protein kinases, and calcium channels. Several anti-cancer drugs are able to suppress growth and induce apoptosis of tumor cells through alteration of lipid raft contents via disrupting lipid raft integrity. -- Highlights: ? The role of lipid rafts in apoptosis ? The pro- and anti-apoptotic effects of lipid raft disruption ? Cancer treatments targeting lipid rafts.

George, Kimberly S. [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States) [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States); Department of Chemistry, Marietta College, Marietta, OH 45750 (United States); Wu, Shiyong, E-mail: wus1@ohio.edu [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States)] [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States)

2012-03-15

303

A systematic survey of lipids across mouse tissues.  

PubMed

Lipids are a diverse collection of macromolecules essential for normal physiology, but the tissue distribution and function for many individual lipid species remain unclear. Here, we report a mass spectrometry survey of lipid abundance across 18 mouse tissues, detecting ~1,000 mass spectrometry features, of which we identify 179 lipids from the glycerolipids, glycerophospholipids, lysophospholipids, acylcarnitines, sphingolipids, and cholesteryl ester classes. Our data reveal tissue-specific organization of lipids and can be used to generate testable hypotheses. For example, our data indicate that circulating triglycerides positively and negatively associated with future diabetes in humans are enriched in mouse adipose tissue and liver, respectively, raising hypotheses regarding the tissue origins of these diabetes-associated lipids. We also integrate our tissue lipid data with gene expression profiles to predict a number of substrates of lipid-metabolizing enzymes, highlighting choline phosphotransferases and sterol O-acyltransferases. Finally, we identify several tissue-specific lipids not present in plasma under normal conditions that may be of interest as biomarkers of tissue injury, and we show that two of these lipids are released into blood following ischemic brain injury in mice. This resource complements existing compendia of tissue gene expression and may be useful for integrative physiology and lipid biology. PMID:24518676

Jain, Mohit; Ngoy, Soeun; Sheth, Sunil A; Swanson, Raymond A; Rhee, Eugene P; Liao, Ronglih; Clish, Clary B; Mootha, Vamsi K; Nilsson, Roland

2014-04-15

304

Amino acid-containing membrane lipids in bacteria.  

PubMed

In the bacterial model organism Escherichia coli only the three major membrane lipids phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin occur, all of which belong to the glycerophospholipids. The amino acid-containing phosphatidylserine is a major lipid in eukaryotic membranes but in most bacteria it occurs only as a minor biosynthetic intermediate. In some bacteria, the anionic glycerophospholipids phosphatidylglycerol and cardiolipin can be decorated with aminoacyl residues. For example, phosphatidylglycerol can be decorated with lysine, alanine, or arginine whereas in the case of cardiolipin, lysine or d-alanine modifications are known. In few bacteria, diacylglycerol-derived lipids can be substituted with lysine or homoserine. Acyl-oxyacyl lipids in which the lipidic part is amide-linked to the alpha-amino group of an amino acid are widely distributed among bacteria and ornithine-containing lipids are the most common version of this lipid type. Only few bacterial groups form glycine-containing lipids, serineglycine-containing lipids, sphingolipids, or sulfonolipids. Although many of these amino acid-containing bacterial membrane lipids are produced in response to certain stress conditions, little is known about the specific molecular functions of these lipids. PMID:19703488

Geiger, Otto; González-Silva, Napoleón; López-Lara, Isabel M; Sohlenkamp, Christian

2010-01-01

305

Preparation of Artificial Plasma Membrane Mimicking Vesicles with Lipid Asymmetry  

PubMed Central

Lipid asymmetry, the difference in lipid distribution across the lipid bilayer, is one of the most important features of eukaryotic cellular membranes. However, commonly used model membrane vesicles cannot provide control of lipid distribution between inner and outer leaflets. We recently developed methods to prepare asymmetric model membrane vesicles, but facile incorporation of a highly controlled level of cholesterol was not possible. In this study, using hydroxypropyl-?-cyclodextrin based lipid exchange, a simple method was devised to prepare large unilamellar model membrane vesicles that closely resemble mammalian plasma membranes in terms of their lipid composition and asymmetry (sphingomyelin (SM) and/or phosphatidylcholine (PC) outside/phosphatidylethanolamine (PE) and phosphatidylserine (PS) inside), and in which cholesterol content can be readily varied between 0 and 50 mol%. We call these model membranes “artificial plasma membrane mimicking” (“PMm”) vesicles. Asymmetry was confirmed by both chemical labeling and measurement of the amount of externally-exposed anionic lipid. These vesicles should be superior and more realistic model membranes for studies of lipid-lipid and lipid-protein interaction in a lipid environment that resembles that of mammalian plasma membranes. PMID:24489974

Lin, Qingqing; London, Erwin

2014-01-01

306

The CD1 size problem: lipid antigens, ligands, and scaffolds.  

PubMed

Whereas research on CD1d has emphasized a few glycosyl ceramides, the broader family of four human CD1 antigen-presenting molecules binds hundreds of distinct self-lipids. Individual lipid types bind within CD1 grooves in different ways, such that they partially fill the groove, match the groove volume, or protrude substantially from the groove. These differing modes of binding can now be connected to differing immunological functions, as individual lipids can act as stimulatory antigens, inhibitory ligands, or space-filling scaffolds. Because each type of CD1 protein folds to produce antigen-binding grooves with differing sizes and shapes, CD1a, CD1b, CD1c, CD1d, and CD1e have distinct mechanisms of capturing self-lipids and exchanging them for foreign lipids. The size discrepancy between endogeneous lipids and groove volume is most pronounced for CD1b. Recent studies show that the large CD1b cavity can simultaneously bind two self-lipids, the antigen, and its scaffold lipid, which can be exchanged for one large bacterial lipid. In this review, we will highlight recent studies showing how cells regulate lipid antigen loading and the roles CD1 groove structures have in control of the presentation of chemically diverse lipids to T cells. PMID:24658584

Ly, Dalam; Moody, D Branch

2014-08-01

307

Control of lipid metabolism by Tachykinin in Drosophila  

PubMed Central

Summary The intestine is a key organ for lipid uptake and distribution, and abnormal intestinal lipid metabolism is associated with obesity and hyperlipidemia. Although multiple regulatory gut hormones secreted from enteroendocrine cells (EEs) regulate systemic lipid homeostasis, such as appetite control and energy balance in adipose tissue, their respective roles regarding lipid metabolism in the intestine are not well understood. We demonstrate that Tachykinins (TKs), one of the most abundant secreted peptides expressed in midgut EEs, regulate intestinal lipid production and subsequently control systemic lipid homeostasis in Drosophila, and that TKs repress lipogenesis in enterocytes (ECs) associated with the TKR99D receptor and PKA signaling. Interestingly, nutrient deprivation enhances the production of TKs in the midgut. Finally, unlike the physiological roles of TKs produced from the brain, gut-derived TKs do not affect behavior, thus demonstrating that gut TK hormones specifically regulate intestinal lipid metabolism without affecting neuronal functions. PMID:25263556

Song, Wei; Veenstra, Jan A.; Perrimon, Norbert

2015-01-01

308

Lipid lowering in liver and chronic kidney disease.  

PubMed

Lipid lowering, particularly with HMG CoA reductase inhibitors ("statins"), reduces the risk of cardiovascular disease. Patients with chronic liver and kidney disease present challenges to the use of lipid medications. In the case of most liver disorders, the concern has been one of safety. There is evidence that most lipid-lowering medications can be used safely in many situations, although large outcomes trials are not available. In contrast, in chronic kidney disease, dosing of lipid medications may require substantial modification depending on creatinine clearance. There are significant alterations in lipid metabolism in chronic kidney disease with concomitant increases in cardiovascular risk. Some data are available on cardiovascular outcomes with dyslipidemia treatment in renal patients. This review will examine lipid physiology and cardiovascular risk in specific liver and kidney diseases and review the evidence for lipid lowering and the use of statin and non-statin therapies in chronic liver and kidney disease. PMID:24840263

Herrick, Cynthia; Litvin, Marina; Goldberg, Anne Carol

2014-06-01

309

Structure of a lipid-bound Extended-Synaptotagmin indicates a role in lipid transfer  

PubMed Central

Growing evidence suggests that close appositions between the endoplasmic reticulum (ER) and other membranes, including appositions with the plasma membrane (PM), mediate exchange of lipids between the two bilayers. The mechanisms of such exchange, which allows lipid transfer independently of vesicular transport, remain poorly understood. The presence of an SMP (synaptotagmin-like-mitochondrial-lipid binding protein) domain, a proposed lipid binding module, in several proteins localized at membrane contact sites raised the possibility that such domains may be implicated in lipid transport1,2. SMP-containing proteins include components of the ERMES complex, an ER-mitochondrial tether3, and the Extended-Synaptotagmins/tricalbins, which are ER-PM tethers4-6. Here we present at 2.44 Å resolution the crystal structure of a fragment of Extended-Synaptotagmin 2 (E-Syt2), including an SMP domain and two adjacent C2 domains. The SMP domain has a beta-barrel structure like protein modules in the TULIP superfamily. It dimerizes to form a ~90 Å long cylinder traversed by a channel lined entirely with hydrophobic residues, with the two C2A-C2B fragments forming arched structures flexibly linked to the SMP domain. Importantly, structural analysis complemented by mass spectrometry revealed the presence of glycerophospholipids in the E-Syt2 SMP channel, indicating a direct role for E-Syts in lipid transport. These findings provide strong evidence for a role of SMP domain containing proteins in the control of lipid transfer at membrane contact sites and have broad implication beyond the field of ER to PM appositions. PMID:24847877

Schauder, Curtis M.; Wu, Xudong; Saheki, Yasunori; Narayanaswamy, Pradeep; Torta, Federico; Wenk, Markus R.; De Camilli, Pietro; Reinisch, Karin M.

2014-01-01

310

Water Permeability of Thin Lipid Membranes  

PubMed Central

The osmotic permeability coefficient, Pf, and the tagged water permeability coefficient, Pd, were determined for thin (<100 A) lipid membranes formed from ox brain lipids plus DL-?-tocopherol; their value of approximately 1 x 10-3 cm/sec is within the range reported for plasma membranes. It was established that Pf = Pd. Other reports that Pf > Pd can be attributed to the presence of unstirred layers in the experimental determination of Pd. Thus, there is no evidence for the existence of aqueous pores in these thin phospholipid membranes. The adsorption onto the membrane of a protein that lowers its electrical resistance by a factor of 103 was found not to affect its water permeability; however, glucose and sucrose were found to interact with the membrane to modify Pf. Possible mechanisms of water transport across these films are discussed, together with the implications of data obtained on these structures for plasma membranes. PMID:6034767

Cass, Albert; Finkelstein, Alan

1967-01-01

311

Retroviral matrix and lipids, the intimate interaction  

PubMed Central

Retroviruses are enveloped viruses that assemble on the inner leaflet of cellular membranes. Improving biophysical techniques has recently unveiled many molecular aspects of the interaction between the retroviral structural protein Gag and the cellular membrane lipids. This interaction is driven by the N-terminal matrix domain of the protein, which probably undergoes important structural modifications during this process, and could induce membrane lipid distribution changes as well. This review aims at describing the molecular events occurring during MA-membrane interaction, and pointing out their consequences in terms of viral assembly. The striking conservation of the matrix membrane binding mode among retroviruses indicates that this particular step is most probably a relevant target for antiviral research. PMID:21385335

2011-01-01

312

Anisotropic spontaneous curvatures in lipid membranes  

NASA Astrophysics Data System (ADS)

Symmetry restrictions due to fluidity require the strain energy in the Helfrich theory of lipid membranes to be locally isotropic in nature. Although this framework is suitable for modeling the interaction of membranes with proteins that generate spherical curvature such as clathrin, there are other important membrane-bending proteins such as BIN-amphiphysin-Rvs proteins that form a cylindrical coat with different curvatures in the longitudinal and the circumferential directions. In this work, we present a detailed mathematical treatment of the theory of lipid membranes incorporating anisotropic spontaneous curvatures. We derive the associated Euler-Lagrange equations and the edge conditions in a generalized setting that allows spatial heterogeneities in the properties of the membrane-protein system. We employ this theory to model the constriction of a membrane tubule by a cylindrical scaffold. In particular, we highlight the role of the equilibrium equation in the tangential plane in regulating the spatial variation of the surface tension field.

Walani, Nikhil; Torres, Jennifer; Agrawal, Ashutosh

2014-06-01

313

Membrane lipids and the origin of life  

NASA Technical Reports Server (NTRS)

The current state of knowledge regarding the development of biological systems is briefly reviewed. At a crucial stage concerning the evolution of such systems, the mechanisms leading to more complex structures must have evolved within the confines of a protected microenvironment, similar to those provided by the contemporary cell membranes. The major components found normally in biomembranes are phospholipids. The structure of the biomembrane is examined, and attention is given to questions concerning the availability of the structural components which are necessary in the formation of primitive lipid membranes. Two approaches regarding the study of protomembranes are discussed. The probability of obtaining ether lipids under prebiotic conditions is considered, taking into account the formation of cyclic and acyclic isoprenoids by the irradiation of isoprene with UV.

Oro, J.; Holzer, G.; Rao, M.; Tornabene, T. G.

1981-01-01

314

Lipid-Based Passivation in Nanofluidics  

PubMed Central

Stretching DNA in nanochannels is a useful tool for direct, visual studies of genomic DNA at the single molecule level. To facilitate the study of the interaction of linear DNA with proteins in nanochannels, we have implemented a highly effective passivation scheme based on lipid bilayers. We demonstrate virtually complete long-term passivation of nanochannel surfaces to a range of relevant reagents, including streptavidin-coated quantum dots, RecA proteins, and RecA–DNA complexes. We show that the performance of the lipid bilayer is significantly better than that of standard bovine serum albumin-based passivation. Finally, we show how the passivated devices allow us to monitor single DNA cleavage events during enzymatic degradation by DNase I. We expect that our approach will open up for detailed, systematic studies of a wide range of protein–DNA interactions with high spatial and temporal resolution. PMID:22432814

2012-01-01

315

Capsinoids suppress fat accumulation via lipid metabolism  

PubMed Central

Capsaicin, found in red peppers, has been reported to have anti-obesity, anti-hypertension, anti-diabetes and anti-inflammatory functions. In the present study, we determined the effect of non-pungent capsinoids on the metabolism of adipocytes. We demonstrated that capsinoids suppressed fat accumulation in vivo and in vitro in mice. Liver, the main tissue of lipid metabolism, was treated by capsinoids, and HMG-CoA reductase, CPT-1, FAT/CD36 and GLUT4 were found to be increased significantly, which demonstrated promotion of the lipid metabolism in liver and adipose tissues. In addition, by adding capsinoids, the induced adipocytes also demonstrated significantly increased levels of HMG-CoA reductase, CPT-1, FAT/CD36 and GLUT4. Oil red O staining also demonstrated that capsinoids decreased fat accumulation in the adipocytes. In conclusion, these results indicate that capsinoids may be worth investigating as a potential cure for obesity. PMID:25421144

HONG, QIN; XIA, CHEN; XIANGYING, HU; QUAN, YUAN

2015-01-01

316

Low abundances of synthetics lipids in phantoms  

NASA Astrophysics Data System (ADS)

Phantoms simulate optical characteristics of tissues. Phantoms use to mimic light distributions in living tissue. Several Phantoms compositions made of silicone, polyester, polyurethane, and epoxy resin have been described in the literature. These kinds of phantoms have the problem of long time preservation. In this work, we describe the fabrication and characterization of phantoms with low concentrations of synthetic lipid using Raman spectroscopy. We fabricate four phantoms made of Polydimethylsiloxane (PDMS). These phantoms have synthetic lipid content of cholesterol and triglycerides. The size of our phantoms is 1 x 1 cm and 5 mm of thickness.We used the point-to-point mapping technique. Finally, we compared advantages and performance of made PDMS and gelatin phantoms.

Villanueva-Luna, A. E.; Santiago-Alvarado, A.; Castro-Ramos, J.; Vazquez-Montiel, S.; Flores-Gil, A.; Aguilar-Soto, J.; Delgado-Atencio, J. A.

2012-03-01

317

Evolving lipid vesicles in prebiotic hydrothermal environments  

NASA Astrophysics Data System (ADS)

We compared three different kinds of lipid vesicles made of saturated fatty acids, unsaturated fatty acids, and phospholipids for their evolutionary capabilities in a simulated hydrothermal environment.Encapsulation of the glycine monomers enhanced the oligomerization of peptides in all cases. Fatty acid vesicles remained stable at higher temperatures and efficiently utilized heat energy for this synthetic reaction. Phospholipid vesicles were destabilized by higher temperatures, and thus were found to be better suited to enhance synthetic reactions at lower temperatures

Furuuchi, Ryo; Imai, Ei-Ichi; Honda, Hajime; Hatori, Kuniyuki; Matsuno, Koichiro

2005-08-01

318

Lipid composition of human seminal plasma.  

PubMed

This study aims at determining the amounts of cholesterol, triglycerides, phospholipids, and nonesterified fatty acids in man's seminal liquid and determining their possible variations linked with the ways of taking and congealing samples. It concludes the determinations of lipids in human seminal liquid are reproducible; the way of taking samples has no real influence; however, it seems best to centrifuge sperm immediately after liquefaction to avoid use of triglycerides and NEFA by the spermatozoa. PMID:2712641

Vignon, F; Koll-Back, M H; Clavert, A; Cranz, C

1989-01-01

319

Control Analysis of Biliary Lipid Secretion  

Microsoft Academic Search

Biliary lipid secretion is a complex process involving a multitude of metabolic pathways. It has always been assumed that bile salt secretion (BSec) fully controls this process. Recently we have demonstrated, that mdr2 P-glycoprotein (P-gp) is an important controlling step as well. In this study we have analysed the control structure of this pathway with Metabolic Control Analysis.Methods: FVB mice

Albert K. Groen; Ronald P. J. Oude Elferink; Joseph M. Tager

1996-01-01

320

Structurally bound lipids in peat humic acids  

Microsoft Academic Search

Humic acids from highly decomposed peat were subjected to oxidation with alkaline cupric oxide (CuO) at 170°C (single oxidation). Oxidation products were isolated as three fractions, oxidized humic acids, fulvic acids and lipophilic compounds. Isolated oxidized humic acids were subsequently re-oxidized (sequential oxidation) under the same conditions, and released lipophilic compounds were isolated. Lipids released during single and sequential oxidations

Keijo Lehtonen; Kari Hänninen; Martti Ketola

2001-01-01

321

Bioorganic chemistry of plant lipid desaturation  

Microsoft Academic Search

The desaturation of long-chain fatty acids is a ubiquitous biotransformation which plays a critical role in the biosynthesis of plant lipids. Species-specific variations lead to unusual fatty acid signatures. Of particular interest is the unique ability of desaturases to oxidize unactivated hydrocarbon chains in such a chemo-, regio- and stereoselective manner. As part of ongoing research into the structure\\/activity relationships

B. Behrouzian; P. H. Buist

2003-01-01

322

Medium chain triglycerides and structured lipids  

Microsoft Academic Search

Lipids are an essential component of our body composition and necessary in our daily food intake. Conventional fats and oils\\u000a are composed of glycerides of long chain fatty acids and are designated as long chain triglycerides (LCT). Body fat as well\\u000a as the fats and oils in our daily intake fall into this category. In enteral and parenteral hyperalimentation, we

Vigen K. Babayan

1987-01-01

323

Light scattering characterization of extruded lipid vesicles  

Microsoft Academic Search

By modeling extruded unilamellar lipid vesicles as thin-walled ellipsoidal shells, mathematical analysis provides simple\\u000a equations which relate the mean elongation and other morphological characteristics of a vesicle population to quantities readily\\u000a obtained from combined static and dynamic light scattering measurements. For SOPC vesicles extruded through a 100 nm pore-size\\u000a filter into a 72.9 mm NaCl solution, the inferred elongation ratio

Albert J. Jin; Daniel Huster; Klaus Gawrisch; Ralph Nossal

1999-01-01

324

Genetics, the environment, and lipid abnormalities  

Microsoft Academic Search

Plasma lipid levels have been identified as major risk factors for cardiovascular disease. Multiple behavioral and environmental\\u000a factors are known to modulate their concentrations in the general population; however, there is dramatic individual variability\\u000a in the association between risk factors and disease, as well as in the individual response to therapeutic intervention. These\\u000a differences may be due to the interaction

Jose M. Ordovas; Haiqing Shen

2002-01-01

325

Lipidic phase membrane protein serial femtosecond crystallography  

PubMed Central

X-ray free electron laser (X-feL)-based serial femtosecond crystallography is an emerging method with potential to rapidly advance the challenging field of membrane protein structural biology. here we recorded interpretable diffraction data from micrometer-sized lipidic sponge phase crystals of the Blastochloris viridis photosynthetic reaction center delivered into an X-feL beam using a sponge phase micro-jet. PMID:22286383

Johansson, Linda C; Arnlund, David; White, Thomas A; Katona, Gergely; DePonte, Daniel P; Weierstall, Uwe; Doak, R Bruce; Shoeman, Robert L; Lomb, Lukas; Malmerberg, Erik; Davidsson, Jan; Nass, Karol; Liang, Mengning; Andreasson, Jakob; Aquila, Andrew; Bajt, Sasa; Barthelmess, Miriam; Barty, Anton; Bogan, Michael J; Bostedt, Christoph; Bozek, John D; Caleman, Carl; Coffee, Ryan; Coppola, Nicola; Ekeberg, Tomas; Epp, Sascha W; Erk, Benjamin; Fleckenstein, Holger; Foucar, Lutz; Graafsma, Heinz; Gumprecht, Lars; Hajdu, Janos; Hampton, Christina Y; Hartmann, Robert; Hartmann, Andreas; Hauser, Günter; Hirsemann, Helmut; Holl, Peter; Hunter, Mark S; Kassemeyer, Stephan; Kimmel, Nils; Kirian, Richard A; Maia, Filipe R N C; Marchesini, Stefano; Martin, Andrew V; Reich, Christian; Rolles, Daniel; Rudek, Benedikt; Rudenko, Artem; Schlichting, Ilme; Schulz, Joachim; Seibert, M Marvin; Sierra, Raymond G; Soltau, Heike; Starodub, Dmitri; Stellato, Francesco; Stern, Stephan; Strüder, Lothar; Timneanu, Nicusor; Ullrich, Joachim; Wahlgren, Weixiao Y; Wang, Xiaoyu; Weidenspointner, Georg; Wunderer, Cornelia; Fromme, Petra; Chapman, Henry N; Spence, John C H; Neutze, Richard

2012-01-01

326

Phytic Acid Inhibits Lipid Peroxidation In Vitro  

PubMed Central

Phytic acid (PA) has been recognized as a potent antioxidant and inhibitor of iron-catalyzed hydroxyl radical formation under in vitro and in vivo conditions. Therefore, the aim of the present study was to investigate, with the use of HPLC/MS/MS, whether PA is capable of inhibiting linoleic acid autoxidation and Fe(II)/ascorbate-induced peroxidation, as well as Fe(II)/ascorbate-induced lipid peroxidation in human colonic epithelial cells. PA at 100??M and 500??M effectively inhibited the decay of linoleic acid, both in the absence and presence of Fe(II)/ascorbate. The observed inhibitory effect of PA on Fe(II)/ascorbate-induced lipid peroxidation was lower (10–20%) compared to that of autoxidation. PA did not change linoleic acid hydroperoxides concentration levels after 24 hours of Fe(II)/ascorbate-induced peroxidation. In the absence of Fe(II)/ascorbate, PA at 100??M and 500??M significantly suppressed decomposition of linoleic acid hydroperoxides. Moreover, PA at the tested nontoxic concentrations (100??M and 500??M) significantly decreased 4-hydroxyalkenal levels in Caco-2 cells which structurally and functionally resemble the small intestinal epithelium. It is concluded that PA inhibits linoleic acid oxidation and reduces the formation of 4-hydroxyalkenals. Acting as an antioxidant it may help to prevent intestinal diseases induced by oxygen radicals and lipid peroxidation products. PMID:24260736

W?glarz, Ludmi?a; Dzier?ewicz, Zofia

2013-01-01

327

Conducting polymer polypyrrole supported bilayer lipid membranes.  

PubMed

Electrochemically synthesized conducting polymer polypyrrole (PPy) film on gold electrode surface was used as a novel support for bilayer lipid membranes (BLMs). Investigations by surface plasmon resonance (SPR) suggest that dimyristoyl-L-alpha-phosphatidylcholine (DMPC) and dimyristoyl-L-alpha-phosphatidyl-L-serine (DMPS) can form BLMs on PPy film surface but dimyristoyl-L-alpha-phosphatidylglycerol (DMPG) and didodecyldimethylammonium bromide (DDAB) can not do so, indicating the formation of PPy supported bilayer lipid membranes (s-BLMs) is dependent on the chemical structure of the lipids used. The self-assembly of DMPC induces a smoother topography than the PPy layer with rms roughness decreasing from 4.484 to 2.914 nm convinced by atomic force microscopy (AFM). Impedance spectroscopy measurements confirm that the deposition of BLM substantially increases the resistance of the system indicating a very densely packed BLM structures. The little change of PPy film in capacitance shows that solvent and electrolyte ions still retain within the porous PPy film after BLM deposition. Therefore, the PPy supported BLM is to some extent comparable to conventional BLM with aqueous medium retaining at its two sides. As an example and preliminary application, horseradish peroxidase (HRP) reconstituted into the s-BLM shows the expected protein activity and can transfer electron from or to the underlying PPy support for its response to electrocatalytic reduction of hydrogen peroxide in solution. Thus the system maybe possesses potential applications to biomimetic membrane studies. PMID:15590292

Shao, Yong; Jin, Yongdong; Wang, Jianlong; Wang, Li; Zhao, Feng; Dong, Shaojun

2005-01-15

328

Stiffened lipid platforms at molecular force foci  

PubMed Central

How mechanical forces are sensed remains largely mysterious. The forces that gate prokaryotic and several eukaryotic channels were found to come from the lipid membrane. Our survey of animal cells found that membrane force foci all have cholesterol-gathering proteins and are reinforced with cholesterol. This result is evident in overt force sensors at the tips of stereocilia for vertebrate hearing and the touch receptor of Caenorhabditis elegans and mammalian neurons. For less specialized cells, cadherins sustain the force between neighboring cells and integrins between cells and matrix. These tension bearers also pass through and bind to a cholesterol-enriched platform before anchoring to cytoskeleton through other proteins. Cholesterol, in alliance with sphingomyelin and specialized proteins, enforces a more ordered structure in the bilayer. Such a stiffened platform can suppress mechanical noise, redirect, rescale, and confine force. We speculate that such platforms may be dynamic. The applied force may allow disordered-phase lipids to enter the platform-staging channel opening in the thinner mobile neighborhood. The platform may also contain specialized protein/lipid subdomains enclosing mechanosensitive channels to open with localized tension. Such a dynamic stage can mechanically operate structurally disparate channels or enzymes without having to tie them directly to cadherin, integrin, or other protein tethers. PMID:23476066

Anishkin, Andriy; Kung, Ching

2013-01-01

329

Crystallizing Membrane Proteins Using Lipidic Mesophases  

PubMed Central

A detailed protocol for crystallizing membrane proteins that makes use of lipidic mesophases is described. This has variously been referred to as the lipid cubic phase or in meso method. The method has been shown to be quite general in that it has been used to solve X-ray crystallographic structures of prokaryotic and eukaryotic proteins, proteins that are monomeric, homo- and hetero-multimeric, chromophore-containing and chromophore-free, and ?-helical and ?-barrel proteins. Its most recent successes are the human engineered ?2-adrenergic and adenosine A2A G protein-coupled receptors. Protocols are provided for preparing and characterizing the lipidic mesophase, for reconstituting the protein into the monoolein-based mesophase, for functional assay of the protein in the mesophase, and for setting up crystallizations in manual mode. Methods for harvesting micro-crystals are also described. The time required to prepare the protein-loaded mesophase and to set up a crystallization plate manually is about one hour. PMID:19390528

Caffrey, Martin; Cherezov, Vadim

2009-01-01

330

Transport and uptake of immunogenic lipids.  

PubMed

An increasing number of lipid mediators have been identified as key modulators of immunity. Among these is a family of glycolipids capable of cellular uptake, loading onto the MHC-like molecule CD1d and stimulation of NKT cells. NKT cells are particularly interesting because they bridge innate and adaptive immunity by coordinating the early events of dendritic cell maturation, recruitment of NK cells, CD4 and CD8 T cells, and B cells at the site of microbial injury. As such, their therapeutic manipulation could be of the greatest interest in vaccine design or active immunotherapy. However, the use of NKT cells as cellular adjuvant of immunity in the clinic will require a better knowledge of the pharmacology of lipid agonists in order to optimize their action and avoid potential unseen off-target effects. We have been studying extracellular transport and cellular uptake of NKT agonists for the past few years. This field is confronted to a very limited prior knowledge and a small set of usable tools. New technology must be put in place and adapted to answering basic immunology questions related to NKT cells. The intimate link between the pharmacology of glycolipids and lipid metabolism makes us believe that great variations of bioactivity could be seen in the general population when NKT agonists are used therapeutically. PMID:23174352

Freigang, Stefan; Kain, Lisa; Teyton, Luc

2013-09-01

331

Microorganism lipid droplets and biofuel development.  

PubMed

Lipid droplet (LD) is a cellular organelle that stores neutral lipids as a source of energy and carbon. However, recent research has emerged that the organelle is involved in lipid synthesis, transportation, and metabolism, as well as mediating cellular protein storage and degradation. With the exception of multi-cellular organisms, some unicellular microorganisms have been observed to contain LDs. The organelle has been isolated and characterized from numerous organisms. Triacylglycerol (TAG) accumulation in LDs can be in excess of 50% of the dry weight in some microorganisms, and a maximum of 87% in some instances. These microorganisms include eukaryotes such as yeast and green algae as well as prokaryotes such as bacteria. Some organisms obtain carbon from CO2 via photosynthesis, while the majority utilizes carbon from various types of biomass. Therefore, high TAG content generated by utilizing waste or cheap biomass, coupled with an efficient conversion rate, present these organisms as bio-tech 'factories' to produce biodiesel. This review summarizes LD research in these organisms and provides useful information for further LD biological research and microorganism biodiesel development. PMID:24355300

Liu, Yingmei; Zhang, Congyan; Shen, Xipeng; Zhang, Xuelin; Cichello, Simon; Guan, Hongbin; Liu, Pingsheng

2013-12-01

332

Comparative effects of lipid-lowering therapies.  

PubMed

The pharmacologic regulation of lipid metabolism in patients with dyslipidemia is unequivocally associated with significant reductions in risk for cardiovascular morbidity and mortality. A number of therapeutic drug classes have been developed in an effort to ever more precisely and intensively modulate lipid metabolism. Statins, fibrates, ezetimibe, and niacin exert their effects via different mechanisms and afford physicians the opportunity to beneficially impact multiple pathways in patients. When used alone or in combination, these drugs decrease risk for the development and progression of atherosclerotic disease. There are strong clinical trial data to support of the use of lipid-lowering therapies in the settings of both primary and secondary prevention. This article (1) discusses the mechanisms of action of antilipidemic medications, (2) reviews dosing regimens and the pharmacokinetic differences among drugs of the same class, (3) assesses risk for drug interactions, and (4) reviews the clinical trial evidence used to support the use of particular antilipidemic medications in specific physiologic settings. The incidence of dyslipidemia is rising worldwide. This trend portends an ever-growing need for the aggressive and judicious use of different antilipidemic medication(s) in patients at risk for all forms of atherosclerotic vascular disease. PMID:15586350

Davidson, Michael H; Toth, Peter P

2004-01-01

333

Heterogeneous and anomalous diffusion inside lipid tubules.  

PubMed

Self-assembled lipid tubules with crystalline bilayer walls are promising candidates for controlled drug delivery vehicles on the basis of their ability to release preloaded biological molecules in a sustained manner. While a previous study has shown that the release rate of protein molecules from lipid tubules depends on the associated molecular mass, suggesting that the pertinent diffusion follows the well-known Stokes-Einstein relationship, only a few attempts have been made toward investigating the details of molecular diffusion in the tubule interior. Herein, we have characterized the diffusion rates of several molecules encapsulated in lipid tubules formed by 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9PC) using the techniques of fluorescence recovery after photobleaching (FRAP) and fluorescence correlation spectroscopy (FCS). Our results show that the mobility of these molecules depends not only on their positions in the DC8,9PC tubules but also on their respective concentrations. While the former indicates that the interior of the DC8,9PC tubules is heterogeneous in terms of diffusion, the latter further highlights the possibility of engineering specific conditions for achieving sustained release of a "drug molecule" over a targeted period of time. In addition, our FCS results indicate that the molecular diffusions inside the crystalline bilayer walls of the DC8,9PC tubules strongly deviate from the normal, stochastic processes, with features characterizing not only anomalous subdiffusions but also motions that are superdiffusive in nature. PMID:18052149

Guo, Lin; Chowdhury, Pramit; Fang, Jiyu; Gai, Feng

2007-12-27

334

Nicotinic Acid regulates glucose and lipid metabolism through lipid independent pathways.  

PubMed

Nicotinic acid (NA) decreases low density lipoprotein (LDL) cholesterol and increases highdensity lipoprotein (HDL) cholesterol at pharmacological doses 500-2000 mg/day, which further inhibits the progression of atherosclerosis and cardiovascular morbidity. However, some effects of NA may be mediated through lipid-independent pathways. NA participates in the regulation of glucose metabolism and the NAD-sirtuin pathway, which may relate to the altered mitochondrial biogenesis. NA exerts its anti-atherosclerotic or side effects via binding to GPR109A and receptor TRPV1. NA may regulate lipid metabolism via adipokines, especially TNF? and adiponectin. NA participates in several cellular pathways, including forkhead transcription factors, sirtuins, and protein kinase B. Though much progress on the regulatory effect of NA has been obtained, much remains to be determined about the exact cellular signal pathways on the regulatory mechanism. To reveal the mechanisms of excessive fatty deposition diseases, it is necessary to investigate the signaling pathways in the muscle, liver, and adipose tissue by which NA controls lipid metabolism. In this paper, we will review recent data on the pharmacological effects of NA and discuss how NA might be harnessed to regulate glucose and lipid metabolism through lipid-independent pathways. PMID:25429652

Liu, Dongwu; Wang, Xiaoqian; Kong, Ling; Chen, Zhiwei

2015-01-01

335

Chemical drug stability in lipids, modified lipids, and polyethylene oxide-containing formulations.  

PubMed

To critique the stability complications seen in formulating poorly water-soluble, problematic drugs in lipids, modified lipids, and polyethylene oxide solvents and surfactants in hard and soft gelatin capsules as well as some parenterals, a literature search was performed and personal experiences, and those of colleagues, collated. The literature is replete with examples of molecules undergoing rapid oxidative degradation in the presence of polyethylene oxide based solvents and surfactants as well as in the presence of unsaturated lipids. More recently appreciated is instability caused by the reaction of amine and amide drugs, with formaldehyde, formic acid found in many of these solvents as impurities and other degradation byproducts of the solvents themselves. One would expect acylation and transacylation reactions to be more common than reported but the literature has some good examples. An added complexity is occasionally seen with the use of hard and soft gelatin capsules with these solvents. The chemical stability of drugs in liquid and semi-solid formulations in the presence of lipids, modified lipids, and polyoxyethylene oxide-based solvents and surfactants can be complex, further exacerbated by the use of gelatin capsules, and can lead to a plethora of degradation pathways often not seen when the same drugs are formulated in solid dosage forms. PMID:23636838

Stella, Valentino J

2013-12-01

336

Smokeless tobacco induced increases in hepatic lipid peroxidation, DNA damage and excretion of urinary lipid metabolites.  

PubMed

The possible role of reactive oxygen species in the toxicity of smokeless tobacco (ST) was explored. The effects of an aqueous smokeless tobacco extract (STE) at doses of 125, 250 and 500 mg STE/kg in rats on the induction of hepatic mitochondrial and microsomal lipid peroxidation and the incidence of hepatic nuclear DNA damage 24 hours post treatment were examined. Dose-dependent increases of 1.8, 2.3 and 4.4-fold in mitochondrial and 1.5, 2.1 and 3.6-fold in microsomal lipid peroxidation occurred at 125, 250 and 500 mg STE/kg, respectively, relative to control values. At these same three doses of STE, 1.3, 1.4 and 2.7-fold increases in hepatic DNA single-strand breaks occurred relative to control values. STE administration also resulted in significant increases in excretion of urinary metabolites. Urinary excretion of the four lipid metabolites malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) was monitored by HPLC for 72 hours after treatment of rats with 125 and 250 mg STE/kg. Increases occurred in the excretion of the four lipid metabolites at every dose and time point with maximum increases in the excretion of all lipid metabolites being observed between 12 and 24 hours post treatment. The results suggest the involvement of an oxidative stress in the toxicity of STE. PMID:8086316

Bagchi, M; Bagchi, D; Hassoun, E A; Stohs, S J

1994-06-01

337

RNA interference silencing of a major lipid droplet protein affects lipid droplet size in Chlamydomonas reinhardtii.  

PubMed

Eukaryotic cells store oils in the chemical form of triacylglycerols in distinct organelles, often called lipid droplets. These dynamic storage compartments have been intensely studied in the context of human health and also in plants as a source of vegetable oils for human consumption and for chemical or biofuel feedstocks. Many microalgae accumulate oils, particularly under conditions limiting to growth, and thus have gained renewed attention as a potentially sustainable feedstock for biofuel production. However, little is currently known at the cellular or molecular levels with regard to oil accumulation in microalgae, and the structural proteins and enzymes involved in the biogenesis, maintenance, and degradation of algal oil storage compartments are not well studied. Focusing on the model green alga Chlamydomonas reinhardtii, the accumulation of triacylglycerols and the formation of lipid droplets during nitrogen deprivation were investigated. Mass spectrometry identified 259 proteins in a lipid droplet-enriched fraction, among them a major protein, tentatively designated major lipid droplet protein (MLDP). This protein is specific to the green algal lineage of photosynthetic organisms. Repression of MLDP gene expression using an RNA interference approach led to increased lipid droplet size, but no change in triacylglycerol content or metabolism was observed. PMID:19915074

Moellering, Eric R; Benning, Christoph

2010-01-01

338

2013 PLANT LIPIDS GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR (JANUARY 27-FEBRUARY 1, 2013 - HOTEL GALVEZ, GALVESTON TX)  

SciTech Connect

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.

Welti, Ruth

2012-11-01

339

Exploration of polar lipid accumulation profiles in Euglena gracilis using LipidBlast, an MS/MS spectral library constructed in silico.  

PubMed

A rapid protocol for polar lipid profiling was applied to Euglena gracilis lipid metabolism by LipidBlast, an MS/MS spectral similarity search tool. The similarity search results suggested anoxia-induced polar lipid metabolism in Euglena characterized by the accumulation of differential lipid classes, carbon chain lengths, and unsaturated bond numbers. The informatics-supported MS spectral search provides an alternative option for global lipid profiling studies. PMID:25036478

Ogawa, Takumi; Furuhashi, Takeshi; Okazawa, Atsushi; Nakai, Rai; Nakazawa, Masami; Kind, Tobias; Fiehn, Oliver; Kanaya, Shigehiko; Arita, Masanori; Ohta, Daisaku

2014-01-01

340

Analysis of Lipoplex Structure and Lipid Phase Changes  

SciTech Connect

Efficient delivery of genetic material to cells is needed for tasks of utmost importance in the laboratory and clinic, such as gene transfection and gene silencing. Synthetic cationic lipids can be used as delivery vehicles for nucleic acids and are now considered the most promising nonviral gene carriers. They form complexes (lipoplexes) with the polyanionic nucleic acids. A critical obstacle for clinical application of the lipid-mediated DNA delivery (lipofection) is its unsatisfactory efficiency for many cell types. Understanding the mechanism of lipid-mediated DNA delivery is essential for their successful application, as well as for a rational design and synthesis of novel cationic lipoid compounds for enhanced gene delivery. A viewpoint now emerging is that the critical factor in lipid-mediated transfection is the structural evolution of lipoplexes within the cell, upon interacting and mixing with cellular lipids. In particular, recent studies showed that the phase evolution of lipoplex lipids upon interaction and mixing with membrane lipids appears to be decisive for transfection success: specifically, lamellar lipoplex formulations, which were readily susceptible to undergoing lamellar-nonlamellar phase transition upon mixing with cellular lipids and were found rather consistently associated with superior transfection potency, presumably as a result of facilitated DNA release. Thus, understanding the lipoplex structure and the phase changes upon interacting with membrane lipids is important for the successful application of the cationic lipids as gene carriers.

Koynova, Rumiana

2012-07-18

341

Syringomycin E channel: a lipidic pore stabilized by lipopeptide?  

PubMed Central

Highly reproducible ion channels of the lipopeptide antibiotic syringomycin E demonstrate unprecedented involvement of the host bilayer lipids. We find that in addition to a pronounced influence of lipid species on the open-channel ionic conductance, the membrane lipids play a crucial role in channel gating. The effective gating charge, which characterizes sensitivity of the conformational equilibrium of the syringomycin E channels to the transmembrane voltage, is modified by the lipid charge and lipid dipolar moment. We show that the type of host lipid determines not only the absolute value but also the sign of the gating charge. With negatively charged bilayers, the gating charge sign inverts with increased salt concentration or decreased pH. We also demonstrate that the replacement of lamellar lipid by nonlamellar with the negative spontaneous curvature inhibits channel formation. These observations suggest that the asymmetric channel directly incorporates lipids. The charges and dipoles resulting from the structural inclusion of lipids are important determinants of the overall energetics that underlies channel gating. We conclude that the syringomycin E channel may serve as a biophysical model to link studies of ion channels with those of lipidic pores in membrane fusion. PMID:11916856

Malev, Valery V; Schagina, Ludmila V; Gurnev, Philip A; Takemoto, Jon Y; Nestorovich, Ekaterina M; Bezrukov, Sergey M

2002-01-01

342

Lipid droplet formation on opposing sides of the endoplasmic reticulum  

PubMed Central

In animal cells, the primary repositories of esterified fatty acids and alcohols (neutral lipids) are lipid droplets that form on the lumenal and/or cytoplasmic side of the endoplasmic reticulum (ER) membrane. A monolayer of amphipathic lipids, intermeshed with key proteins, serves to solubilize neutral lipids as they are synthesized and desorbed. In specialized cells, mobilization of the lipid cargo for delivery to other tissues occurs by secretion of lipoproteins into the plasma compartment. Serum lipoprotein assembly requires an obligate structural protein anchor (apolipoprotein B) and a dedicated chaperone, microsomal triglyceride transfer protein. By contrast, lipid droplets that form on the cytoplasmic face of the ER lack an obligate protein scaffold or any required chaperone/lipid transfer protein. Mobilization of neutral lipids from the cytosol requires regulated hydrolysis followed by transfer of the products to different organelles or export from cells. Several proteins play a key role in controlling droplet number, stability, and catabolism; however, it is our premise that their formation initiates spontaneously, solely as a consequence of neutral lipid synthesis. This default pathway directs droplets into the cytoplasm where they accumulate in many lipid disorders. PMID:22701043

Sturley, Stephen L.; Hussain, M. Mahmood

2012-01-01

343

Thermal Adaptation of the Archaeal and Bacterial Lipid Membranes  

PubMed Central

The physiological characteristics that distinguish archaeal and bacterial lipids, as well as those that define thermophilic lipids, are discussed from three points of view that (1) the role of the chemical stability of lipids in the heat tolerance of thermophilic organisms: (2) the relevance of the increase in the proportion of certain lipids as the growth temperature increases: (3) the lipid bilayer membrane properties that enable membranes to function at high temperatures. It is concluded that no single, chemically stable lipid by itself was responsible for the adaptation of surviving at high temperatures. Lipid membranes that function effectively require the two properties of a high permeability barrier and a liquid crystalline state. Archaeal membranes realize these two properties throughout the whole biological temperature range by means of their isoprenoid chains. Bacterial membranes meet these requirements only at or just above the phase-transition temperature, and therefore their fatty acid composition must be elaborately regulated. A recent hypothesis sketched a scenario of the evolution of lipids in which the “lipid divide” emerged concomitantly with the differentiation of archaea and bacteria. The two modes of thermal adaptation were established concurrently with the “lipid divide.” PMID:22927779

Koga, Yosuke

2012-01-01

344

Conservation of lipid functions in cytochrome bc complexes.  

PubMed

Lipid binding sites and properties are compared in two sub-families of hetero-oligomeric membrane protein complexes known to have similar functions in order to gain further understanding of the role of lipid in the function, dynamics, and assembly of these complexes. Using the crystal structure information for both complexes, we compared the lipid binding properties of the cytochrome b(6)f and bc(1) complexes that function in photosynthetic and respiratory membrane energy transduction. Comparison of lipid and detergent binding sites in the b(6)f complex with those in bc(1) shows significant conservation of lipid positions. Seven lipid binding sites in the cyanobacterial b(6)f complex overlap three natural sites in the Chlamydomonas reinhardtii algal complex and four sites in the yeast mitochondrial bc(1) complex. The specific identity of lipids is different in b(6)f and bc(1) complexes: b(6)f contains sulfoquinovosyldiacylglycerol, phosphatidylglycerol, phosphatidylcholine, monogalactosyldiacylglycerol, and digalactosyldiacylglycerol, whereas cardiolipin, phosphatidylethanolamine, and phosphatidic acid are present in the yeast bc(1) complex. The lipidic chlorophyll a and ?-carotene (?-car) in cyanobacterial b(6)f, as well as eicosane in C. reinhardtii, are unique to the b(6)f complex. Inferences of lipid binding sites and functions were supported by sequence, interatomic distance, and B-factor information on interacting lipid groups and coordinating amino acid residues. The lipid functions inferred in the b(6)f complex are as follows: (i) substitution of a transmembrane helix by a lipid and chlorin ring, (ii) lipid and ?-car connection of peripheral and core domains, (iii) stabilization of the iron-sulfur protein transmembrane helix, (iv) n-side charge and polarity compensation, and (v) ?-car-mediated super-complex with the photosystem I complex. PMID:21978667

Hasan, S Saif; Yamashita, Eiki; Ryan, Christopher M; Whitelegge, Julian P; Cramer, William A

2011-11-18

345

Surface-mitigated lipid organization and dynamics  

NASA Astrophysics Data System (ADS)

Supported bilayers, fluid phospholipid films of molecular thicknesses, have been of considerable interest as model biological membranes both for fundamental studies of cell surface mechanisms and for designing biosensors and assays for membrane-targets. Beyond biology, interfacial organization of amphiphiles and lipids into a discrete number of molecular layers provides arguably one of the most pristine experimental realizations of a self-organized, two-dimensional system. Consequently the construct of a supported membrane is an experimental test-bed for the study of a rich variety of interface-dominated processes including surface melting, low-dimensional phase transitions, surface dynamics, and phase coexistence/separation. A central hypothesis of this dissertation is that by controlling the spatial and temporal variations of solid surface properties we manipulate the adherent membrane's organization. Such control over structural organization provides a means to tune a variety of membrane physical properties including lateral tension, spatial contiguity, local curvature, and membrane spreadability. Chapter 1 introduces the reader to static patterning of fluids and elastomers, and summarizes my specific contributions. The following two chapters are each divided into a pair of themed inquiries, each of which is associated with a publication. Chapter 2 introduces two ways to dynamically pattern lipid films using substrates. One is a top-down, switchable imposition of membrane structure based on elastomer substrate deformation. The other approach uses patterns of surface-energy to manipulate the kinetics and morphology of membrane self-assembly. Chapter 3 consists of two inquiries into surface-mitigated dynamic phenomena that occur between the leaflets of a lipid bilayer. Namely, a novel means of producing and detecting lateral interleaflet slip, and a means to localize a transverse lipid interdigitation that accompanies a phase-change. The final chapter is a review of a fluorescence-based diffusion analysis technique (FRAP) I have adapted and packaged. This dissertation represents a concerted effort to develop new techniques for the manipulation and characterization of molecularly thin lipid films. Such manipulations open new avenues of investigations into material properties of thin films, such as the role of curvature, fluidity, and interleaflet interactions. The following pages examine a narrow range of the dynamic membrane reconfigurations enabled by these manipulations.

Sanii, Babak

346

Mining the genome for lipid genes.  

PubMed

Mining of the genome for lipid genes has since the early 1970s helped to shape our understanding of how triglycerides are packaged (in chylomicrons), repackaged (in very low density lipoproteins; VLDL), and hydrolyzed, and also how remnant and low-density lipoproteins (LDL) are cleared from the circulation. Gene discoveries have also provided insights into high-density lipoprotein (HDL) biogenesis and remodeling. Interestingly, at least half of these key molecular genetic studies were initiated with the benefit of prior knowledge of relevant proteins. In addition, multiple important findings originated from studies in mouse, and from other types of non-genetic approaches. Although it appears by now that the main lipid pathways have been uncovered, and that only modulators or adaptor proteins such as those encoded by LDLRAP1, APOA5, ANGPLT3/4, and PCSK9 are currently being discovered, genome wide association studies (GWAS) in particular have implicated many new loci based on statistical analyses; these may prove to have equally large impacts on lipoprotein traits as gene products that are already known. On the other hand, since 2004 - and particularly since 2010 when massively parallel sequencing has become de rigeur - no major new insights into genes governing lipid metabolism have been reported. This is probably because the etiologies of true Mendelian lipid disorders with overt clinical complications have been largely resolved. In the meantime, it has become clear that proving the importance of new candidate genes is challenging. This could be due to very low frequencies of large impact variants in the population. It must further be emphasized that functional genetic studies, while necessary, are often difficult to accomplish, making it hazardous to upgrade a variant that is simply associated to being definitively causative. Also, it is clear that applying a monogenic approach to dissect complex lipid traits that are mostly of polygenic origin is the wrong way to proceed. The hope is that large-scale data acquisition combined with sophisticated computerized analyses will help to prioritize and select the most promising candidate genes for future research. We suggest that at this point in time, investment in sequence technology driven candidate gene discovery could be recalibrated by refocusing efforts on direct functional analysis of the genes that have already been discovered. This article is part of a Special Issue entitled: From Genome to Function. PMID:24798233

Kuivenhoven, Jan Albert; Hegele, Robert A

2014-10-01

347

Lipids around the Clock: Focus on Circadian Rhythms and Lipid Metabolism.  

PubMed

Disorders of lipid and lipoprotein metabolism and transport are responsible for the development of a large spectrum of pathologies, ranging from cardiovascular diseases, to metabolic syndrome, even to tumour development. Recently, a deeper knowledge of the molecular mechanisms that control our biological clock and circadian rhythms has been achieved. From these studies it has clearly emerged how the molecular clock tightly regulates every aspect of our lives, including our metabolism. This review analyses the organisation and functioning of the circadian clock and its relevance in the regulation of physiological processes. We also describe metabolism and transport of lipids and lipoproteins as an essential aspect for our health, and we will focus on how the circadian clock and lipid metabolism are greatly interconnected. Finally, we discuss how a deeper knowledge of this relationship might be useful to improve the recent spread of metabolic diseases. PMID:25665169

Gnocchi, Davide; Pedrelli, Matteo; Hurt-Camejo, Eva; Parini, Paolo

2015-01-01

348

Response of pigeon guillemots to variable abundance of high-lipid and low-lipid prey  

USGS Publications Warehouse

Populations of the pigeon guillemot (Cepphus columba) and other piscivores have been in decline for several decades in the Gulf of Alaska and Bering Sea, and a decline in abundance of lipid-rich schooling fishes is hypothesized as the major cause. We tested this hypothesis by studying the breeding biology of pigeon guillemots during 1995-1999 while simultaneously measuring prey abundance with beach seines and bottom trawls. Our study area (Kachemak Bay, Alaska) comprises two oceanographically distinct areas. Populations of a lipid-rich schooling fish, Pacific sand lance (Ammodytes hexapterus), were higher in the warmer Inner Bay than in the colder Outer Bay, and sand lance abundance was higher during warm years. Populations of low-lipid content demersal fishes were similar between areas. Chick survival to age 15 days was 47% higher in the Inner Bay (high-lipid diet) than in the Outer Bay (low-lipid diet), and estimated reproductive success (chicks fledged nest-1) was 62% higher in the Inner Bay than in the Outer Bay. Chick provisioning rate (kJ chick-1 h-1) increased with the proportion of sand lance in the diet (r2=0.21), as did growth rate (g day-1) of younger (beta) chicks in two-chick broods (r2=0.14). Pigeon guillemots in the Inner Bay switched to demersal prey during years of below-average sand lance abundance, and these birds reacted to 38-fold interannual changes in sand lance abundance with reductions in beta chick growth rates, with no decline in beta chick survival. In contrast, the proportion of nests experiencing brood reduction in the Outer Bay (demersal diet) increased >300% during years of below-average demersal abundance, although demersal fish abundance varied only 4-fold among years. Our results support the hypothesis that recovery of pigeon guillemot populations from the effects of the Exxon Valdez oil spill is limited by availability of lipid-rich prey.

Litzow, M.A.; Piatt, J.F.; Prichard, A.K.; Roby, D.D.

2002-01-01

349

Characterization of Horizontal Lipid Bilayers as a Model System to Study Lipid Phase Separation  

PubMed Central

Abstract Artificial lipid membranes are widely used as a model system to study single ion channel activity using electrophysiological techniques. In this study, we characterize the properties of the artificial bilayer system with respect to its dynamics of lipid phase separation using single-molecule fluorescence fluctuation and electrophysiological techniques. We determined the rotational motions of fluorescently labeled lipids on the nanosecond timescale using confocal time-resolved anisotropy to probe the microscopic viscosity of the membrane. Simultaneously, long-range mobility was investigated by the lateral diffusion of the lipids using fluorescence correlation spectroscopy. Depending on the solvent used for membrane preparation, lateral diffusion coefficients in the range Dlat = 10–25 ?m2/s and rotational diffusion coefficients ranging from Drot = 2.8 ? 1.4 × 107 s?1 were measured in pure liquid-disordered (Ld) membranes. In ternary mixtures containing saturated and unsaturated phospholipids and cholesterol, liquid-ordered (Lo) domains segregated from the Ld phase at 23°C. The lateral mobility of lipids in Lo domains was around eightfold lower compared to those in the Ld phase, whereas the rotational mobility decreased by a factor of 1.5. Burst-integrated steady-state anisotropy histograms, as well as anisotropy imaging, were used to visualize the rotational mobility of lipid probes in phase-separated bilayers. These experiments and fluorescence correlation spectroscopy measurements at different focal diameters indicated a heterogeneous microenvironment in the Lo phase. Finally, we demonstrate the potential of the optoelectro setup to study the influence of lipid domains on the electrophysiological properties of ion channels. We found that the electrophysiological activity of gramicidin A (gA), a well-characterized ion-channel-forming peptide, was related to lipid-domain partitioning. During liquid-liquid phase separation, gA was largely excluded from Lo domains. Simultaneously, the number of electrically active gA dimers increased due to the increased surface density of gA in the Ld phase. PMID:20550901

Honigmann, Alf; Walter, Claudius; Erdmann, Frank; Eggeling, Christian; Wagner, Richard

2010-01-01

350

Structure of polymerizable lipid bilayers: water profile of a diacetylenic lipid bilayer using elastic neutron scattering.  

PubMed

Elastic neutron scattering experiments have been used to study the hydration of multibilayers of 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9PC). Previously published FTIR spectroscopic data had suggested, based on shifts in the carbonyl (C = O) stretch frequencies, that the phosphocholine headgroup in these polymerizable lipid bilayers was much less hydrated than that of saturated phosphatidylcholines. Our results demonstrate that the DC8,9PC headgroup is at least as well hydrated as that of dipalmitoylphosphatidylcholine (DPPC), a saturated lipid, under the same conditions. PMID:2317485

Blechner, S L; Skita, V; Rhodes, D G

1990-03-01

351

Contributions of Gaussian Curvature and Nonconstant Lipid Volume to Protein Deformation of Lipid Bilayers  

PubMed Central

An elastic model for membrane deformations induced by integral membrane proteins is presented. An earlier theory is extended to account for nonvanishing saddle splay modulus within lipid monolayers and perturbations to lipid volume proximal to the protein. Analytical results are derived for the deformation profile surrounding a single cylindrical protein inclusion, which compare favorably to coarse-grained simulations over a range of protein sizes. Numerical results for multi-protein systems indicate that membrane-mediated interactions between inclusions are strongly affected by Gaussian curvature and display nonpairwise additivity. Implications for the aggregation of proteins are discussed. PMID:17098794

Brannigan, Grace; Brown, Frank L. H.

2007-01-01

352

Systems-Level Lipid Analysis Methodologies for Qualitative and Quantitative Investigation of Lipid Signaling Events During Wound Healing  

PubMed Central

Objective Accumulating evidence implicates a prominent role for lipid signaling molecules in the regulation of wound healing. These lipids regulate hemostasis, onset and resolution of inflammation, migration and proliferation cells, angiogenesis, epithelialization, and remodeling of collagen. The objective of this overview is to demonstrate the applicability of systems level lipid analyses to identify and quantify lipid involved in events leading to wound healing. Approach Current advances in liquid chromatography coupled to tandem mass spectrometry have provided the means for carrying out quantitative and qualitative analysis of lipids at a systems level. This emerging field is collectively referred to as lipidomics and its potential in wound healing research is largely ignored. Results While comprehensive applications of lipidomics in wound healing are limited, studies carried out by the authors as well as others demonstrate distinct changes in the lipidome during the wound healing process. Innovation Until recently, investigations into lipids were limited to the study of a few lipids at a time. Lipidomics approaches provide the capability to quantitatively and qualitatively assay almost the full complement of lipid signaling circuits at the same time. This allows obtaining a system level understanding of changes to the entire lipidome during the wound healing process. Conclusion The technology provides promising approach to understanding new signaling pathways based on lipids involved in wound healing. The understanding gained from such studies has the potential for the development of novel lipid based treatment strategies to promote wound healing. PMID:24527363

Wijesinghe, Dayanjan S.; Chalfant, Charles E.

2013-01-01

353

Internal lipids of felted, yellowed and pathologically thin wool.  

PubMed

The keratin fibers contain small amount of the internal lipids which are in free state or bound with fiber proteins via tioester of 18-methyleicosanoic acid. Today the origin of these lipids, their composition and functional properties are still not found. Therefore, our objective was to examine the content and composition of internal lipids in sheep's wool with different defects. We observed that regardless of the type of fibers defect there are significant changes especially in the quality composition of the internal lipids, although the total content of free and covalently bound lipids in all cases is practically identical. Notably, both free and covalently bound lipids composition of felted and simultaneously felted and yellowed wool is characterized by changes in contents mainly of free fatty acids and ceramides whereas abnormal thinning of fibers is accompanied only by a decrease of sulfolipids. PMID:24834727

Tkachuk, V M; Havrylyak, V V; Stapay, P V; Sediloc, H M

2014-01-01

354

Lipid nanoparticles for the topical delivery of retinoids and derivatives.  

PubMed

Retinoids are lipophilic compounds that are highly used in cosmetics/therapeutics for skin disorders. Conventional formulations are limited by poor water solubility, high chemical/photochemical instability and the irritation of retinoids. Interestingly, lipid nanoparticles enable the administration of retinoids in aqueous media, providing drug stabilization and controlled release. Recently, it has been demonstrated that retinoids in solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and nanocapsules can decrease degradation, improve targeting and enhance efficacy for the treatment of skin disorders. This article focuses on the formulation, fabrication, characterization and in vitro/in vivo evaluation of solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and nanocapsules loaded with retinoids for skin administration. Furthermore, the incorporation of these lipid nanoparticles into secondary vehicles is discussed. PMID:25600970

Morales, Javier O; Valdés, Karina; Morales, Javier; Oyarzun-Ampuero, Felipe

2015-01-01

355

Maternal lipids in pre-eclampsia: innocent bystander or culprit?  

PubMed

Pre-eclampsia continues to be a challenge--to understand the underlying pathogenesis and to prevent or treat in the clinical setting. One area of potential therapies opening up is treatment of maternal lipids and clinical trials are underway using statins in early pre-eclampsia. At present, most potential therapies to treat lipids cannot be recommended for general use in pregnancy and if we were to target maternal lipids to reduce rates of pre-eclampsia, very large numbers of women may need to be treated. Prior to reaching that point, we first need to understand whether maternal lipids are pathogenic in the processes underlying pre-eclampsia. The aim of this review is to examine the role of lipids in the pathogenesis and outcomes of pre-eclampsia, how abnormal lipid genes may be implicated and consider whether treatment of hyperlipidemia has a more general place in the prevention or treatment of pre-eclampsia. PMID:25121342

Barrett, Helen L; Dekker Nitert, Marloes; McIntyre, H David; Callaway, Leonie K

2014-11-01

356

Lipid fluorination enables phase separation from fluid phospholipid bilayers.  

PubMed

To probe the effect of lipid fluorination on the formation of lipid domains in phospholipid bilayers, several new fluorinated and non-fluorinated synthetic lipids were synthesised, and the extent of phase separation of these lipids from phospholipid bilayers of different compositions was determined. At membrane concentrations as low as 1% mol/mol, both fluorinated and non-fluorinated lipids were observed to phase separate from a gel-phase (solid ordered) phospholipid matrix, but bilayers in a liquid disordered state caused no phase separation; if the gel-phase samples were heated above the transition temperature, then phase separation was lost. We found incorporation of perfluoroalkyl groups into the lipid enhanced phase separation, to such an extent that phase separation was observed from cholesterol containing bilayers in the liquid ordered phase. PMID:16763685

Webb, Simon J; Greenaway, Kevin; Bayati, Marzieh; Trembleau, Laurent

2006-06-21

357

Polyunsaturated Fatty Acids in Lipid Bilayers and Tubules  

NASA Astrophysics Data System (ADS)

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.

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

2007-03-01

358

Enhanced lipid production in Chlorella pyrenoidosa by continuous culture.  

PubMed

Usually microalgae growth and lipid accumulation do not run in parallel throughout cultivation, which necessarily lowers overall lipid productivity. However, we show through batch and feed-batch studies of Chlorella pyrenoidosa XQ-20044 that by varying the nitrate concentration, conditions which produce fairly high lipid content could be achieved without sacrificing algal growth. Simultaneous microalgae growth and lipid production was achieved in continuous chemostat culture when the specific nitrate input rate was in the range of 0.78-4.56mmolg(-1)d(-1). Moreover, the maximum lipid productivity (144.93mgL(-1)d(-1)) in the continuous culture was significantly higher than in batch culture (96.28mgL(-1)d(-1)), thus indicating the feasibility and great advantage of one-step production of microalgal lipids. PMID:24717322

Wen, Xiaobin; Geng, Yahong; Li, Yeguang

2014-06-01

359

Applications of Mass Spectrometry to Lipids and Membranes  

PubMed Central

Lipidomics, a major part of metabolomics, constitutes the detailed analysis and global characterization, both spatial and temporal, of the structure and function of lipids (the lipidome) within a living system. As with proteomics, mass spectrometry has earned a central analytical role in lipidomics, and this role will continue to grow with technological developments. Currently, there exist two mass spectrometry-based lipidomics approaches, one based on a division of lipids into categories and classes prior to analysis, the “comprehensive lipidomics analysis by separation simplification” (CLASS), and the other in which all lipid species are analyzed together without prior separation, shotgun. In exploring the lipidome of various living systems, novel lipids are being discovered, and mass spectrometry is helping characterize their chemical structure. Deuterium exchange mass spectrometry (DXMS) is being used to investigate the association of lipids and membranes with proteins and enzymes, and imaging mass spectrometry (IMS) is being applied to the in situ analysis of lipids in tissues. PMID:21469951

Harkewicz, Richard; Dennis, Edward A.

2012-01-01

360

Fish oil-containing lipid emulsions in patients with sepsis.  

PubMed

Lipid emulsions based on soybean oil have been an integral part of parenteral nutrition supplying n-6 fatty acids, with possible negative effects in critically ill patients. Newer lipid emulsions supply less n-6 fatty acids. In addition, fish oil-based lipids may be included in the lipid component of parenteral nutrition. While clinical benefits of lipid emulsions with a reduced fraction in n-6 lipids and the addition of fish oil have been described in postoperative patients, data are less clear in critically ill or septic patients. Recent data suggest that beneficial effects may be achieved when used early but clearly more data are needed to come to a definitive conclusion. The present commentary will highlight current data in critically ill and septic patients and the use of fish oil as a part of parenteral nutrition. PMID:20236465

Mayer, Konstantin; Seeger, Werner

2010-01-01

361

Insect endosymbiont proliferation is limited by lipid availability  

PubMed Central

Spiroplasma poulsonii is a maternally transmitted bacterial endosymbiont that is naturally associated with Drosophila melanogaster. S. poulsonii resides extracellularly in the hemolymph, where it must acquire metabolites to sustain proliferation. In this study, we find that Spiroplasma proliferation specifically depletes host hemolymph diacylglyceride, the major lipid class transported by the lipoprotein, Lpp. RNAi-mediated knockdown of Lpp expression, which reduces the amount of circulating lipids, inhibits Spiroplasma proliferation demonstrating that bacterial proliferation requires hemolymph-lipids. Altogether, our study shows that an insect endosymbiont acquires specific lipidic metabolites from the transport lipoproteins in the hemolymph of its host. In addition, we show that the proliferation of this endosymbiont is limited by the availability of hemolymph lipids. This feature could limit endosymbiont over-proliferation under conditions of host nutrient limitation as lipid availability is strongly influenced by the nutritional state. DOI: http://dx.doi.org/10.7554/eLife.02964.001 PMID:25027439

Herren, Jeremy K; Paredes, Juan C; Schüpfer, Fanny; Arafah, Karim; Bulet, Philippe; Lemaitre, Bruno

2014-01-01

362

Imaging of lipid species by MALDI mass spectrometry  

PubMed Central

Recent developments in MALDI have enabled direct detection of lipids as intact molecular species present within cellular membranes. Abundant lipid-related ions are produced from the direct analysis of thin tissue slices when sequential spectra are acquired across a tissue surface that has been coated with a MALDI matrix. The lipid-derived ions can often be distinguished from other biomolecules because of the significant mass defect that these ions present due to the large number of covalently bound hydrogen atoms in hydrophobic molecules such as lipids. Collisional activation of the molecular ions can be used to determine the lipid family and often structurally define the molecular species. Specific examples in the detection of phospholipids, sphingolipids, and glycerolipids are presented with images of mouse brain and kidney tissue slices. Regional distribution of many different lipid molecular species and Na+ and K+ attachment ions often define anatomical regions within the tissues. PMID:19050313

Murphy, Robert C.; Hankin, Joseph A.; Barkley, Robert M.

2009-01-01

363

Proton magnetic resonance imaging of lipid in pecan embryos  

Microsoft Academic Search

Magnetic resonance images of plant tissues typically are manifestations of water protons in tissues. Within oilseeds, however,\\u000a lipids contain a major portion of the mobile protons, which should enable specific imaging of lipids. In this study, experiments\\u000a were done to demonstrate spin-echo imaging (SEI) and chemical-shift imaging (CSI) of lipid within nonimbibed and imbibed embryos\\u000a of pecan (Carya illinoensis), a

John M. Halloina; Thomas G. Cooper; E. James Potchen; Tommy E. Thompson

1993-01-01

364

Nile red: a selective fluorescent stain for intracellular lipid droplets  

Microsoft Academic Search

We report that the dye nile red, 9-diethylamino-5H-benzo(a)phenoxazine-5-one, is an excellent vital stain for the detection of intracellular lipid droplets by fluorescence microscopy and flow cytofluorometry. The specificity of the dye for lipid droplets was assessed on cultured aortic smooth muscle cells and on cultured peritoneal macrophages that were incubated with acetylated low density lipoprotein to induce cytoplasmic lipid overloading.

PHILLIP GREENSPAN; EUGENE P. MAYER; STANLEY D. FOWLER

1985-01-01

365

Nonequilibrium Behavior in Supported Lipid Membranes Containing Cholesterol  

Microsoft Academic Search

We investigate lateral organization of lipid domains in vesicles versus supported membranes and monolayers. The lipid mixtures used are predominantly DOPC\\/DPPC\\/Chol and DOPC\\/BSM\\/Chol, which have been previously shown to produce coexisting liquid phases in vesicles and monolayers. In a monolayer at an air-water interface, these lipids have miscibility transition pressures of ?12–15mN\\/m, which can rise to 32mN\\/m if the monolayer

Benjamin L. Stottrup; Sarah L. Veatch; Sarah L. Keller

2004-01-01

366

Kinetic and thermodynamic aspects of lipid translocation in biological membranes.  

PubMed Central

A theoretical analysis of the lipid translocation in cellular bilayer membranes is presented. We focus on an integrative model of active and passive transport processes determining the asymmetrical distribution of the major lipid components between the monolayers. The active translocation of the aminophospholipids phosphatidylserine and phosphatidylethanolamine is mathematically described by kinetic equations resulting from a realistic ATP-dependent transport mechanism. Concerning the passive transport of the aminophospholipids as well as of phosphatidylcholine, sphingomyelin, and cholesterol, two different approaches are used. The first treatment makes use of thermodynamic flux-force relationships. Relevant forces are transversal concentration differences of the lipids as well as differences in the mechanical states of the monolayers due to lateral compressions. Both forces, originating primarily from the operation of an aminophospholipid translocase, are expressed as functions of the lipid compositions of the two monolayers. In the case of mechanical forces, lipid-specific parameters such as different molecular surface areas and compression force constants are taken into account. Using invariance principles, it is shown how the phenomenological coefficients depend on the total lipid amounts. In a second approach, passive transport is analyzed in terms of kinetic mechanisms of carrier-mediated translocation, where mechanical effects are incorporated into the translocation rate constants. The thermodynamic as well as the kinetic approach are applied to simulate the time-dependent redistribution of the lipid components in human red blood cells. In the thermodynamic model the steady-state asymmetrical lipid distribution of erythrocyte membranes is simulated well under certain parameter restrictions: 1) the time scales of uncoupled passive transbilayer movement must be different among the lipid species; 2) positive cross-couplings of the passive lipid fluxes are needed, which, however, may be chosen lipid-unspecifically. A comparison of the thermodynamic and the kinetic approaches reveals that antiport mechanisms for passive lipid movements may be excluded. Simulations with kinetic symport mechanisms are in qualitative agreement with experimental data but show discrepancies in the asymmetrical distribution for sphingomyelin. PMID:10049313

Frickenhaus, S; Heinrich, R

1999-01-01

367

Neutral lipids in macroalgal spores and their role in swimming  

Microsoft Academic Search

We followed changes in the neutral lipid content of actively swimming zoospores of the palm kelp Pterygophora californica in a laboratory experiment to investigate the degree to which spore swimming is fueled by endogenous lipid reserves. The\\u000a neutral lipid content of individual zoospores during the experiment was measured by flow cytometry using Nile Red, a fluorescent\\u000a stain that is specific

D. C. Reed; M. A. Brzezinski; D. A. Coury; W. M. Graham; R. L. Petty

1999-01-01

368

Super-resolution Microscopy of Lipid Bilayer Phases  

PubMed Central

Sub-diffraction optical imaging with nanometer resolution of lipid phase separated regions is reported. Merocyanine 540, a probe whose fluorescence is sensitive to the lipid phase, is combined with super-resolution imaging to distinguish the liquid and gel phase nanoscale domains of lipid bilayers supported on glass. The monomer-dimer equilibrium of MC 540 in membranes is deemed responsible for the population difference of single molecule fluorescence bursts in the different phase regions. The extension of this method to other binary or ternary lipid models or natural systems provides a promising new super-resolution strategy. PMID:21405121

Kuo, Chinkuei; Hochstrasser, Robin M.

2011-01-01

369

Using Monomolecular Films to Characterize Lipid Lateral Interactions  

PubMed Central

Summary Membrane lipids are structurally diverse in ways that far exceed the role envisioned by Singer and Nicholson of simply providing a fluid bilayer matrix in which proteins reside. Current models of lipid organization in membranes postulate that lipid structural diversity enables nonrandom lipid mixing in each leaflet of the bilayer, resulting in regions with special physical and functional properties, i.e., microdomains. Central to understanding the tendencies of membrane lipids to mix nonrandomly in biomembranes is the identification and evaluation of structural features that control membrane lipid lateral mixing interactions in simple model membranes. The surface balance provides a means to evaluate the lateral interactions among different lipids at a most fundamental level—mixed in binary/ternary combinations that self-assemble at the air–water interface as monomolecular films, i.e., monolayers. Analysis of surface pressure and interfacial potential as a function of average cross-sectional molecular area provide insights into hydrocarbon chain ordering, lateral compressibility/elasticity, and dipole effects under various conditions including those that approximate one leaflet of a bilayer. Although elegantly simple in principle, effective use of the surface balance requires proper attention to various experimental parameters, which are described herein. Adequate attention to these experimental parameters ensures that meaningful insights are obtained into the lipid lateral interactions and enables lipid monolayers to serve as a basic platform for use with other investigative approaches. PMID:18214373

Brown, Rhoderick E.; Brockman, Howard L.

2008-01-01

370

Adhesion promotes phase separation in mixed-lipid membranes  

NASA Astrophysics Data System (ADS)

We investigate the interplay of domain formation and adhesion in mixed-lipid membranes. Giant unilamellar vesicles consisting of two- and three-component lipid mixtures are studied using confocal fluorescence microscopy. Upon driving the system towards the demixing transition, phase separation is invariably found to occur first in regions where membranes adhere to one another, despite identical lipid headgroups and negligible curvature effects. We propose a simple generic mechanism based on the suppression of thermal shape fluctuations to explain these observations. Our findings suggest novel possibilities by which biomembranes can create and utilize lateral lipid heterogeneities.

Gordon, V. D.; Deserno, M.; Andrew, C. M. J.; Egelhaaf, S. U.; Poon, W. C. K.

2008-11-01

371

Effects of sulfur dioxide on lichen lipids and fatty acids.  

PubMed

Lipids and fatty acids were studied in some lichen species after exposure to 1 ppm of aqueous sulfur dioxide. The changes in lipid composition are specific to the lichen species tested. The exposure of lichens to SO2 resulted in a slight reduction of the total phospholipid content. The amount of betaine lipid diacylglyceryltrimethylhomoserine was increased in Stereocaulon paschale, but the level of this lipid was not changed in Peltigera aphthosa. An increase in fatty acid unsaturation in lichens in response to the effect of SO2 probably has adaptive significance. PMID:9986914

Bychek-Guschina, I A; Kotlova, E R; Heipieper, H

1999-01-01

372

Thermal stability of ladderane lipids as determined by hydrous pyrolysis  

USGS Publications Warehouse

Anaerobic ammonium oxidation (anammox) has been recognized as a major process resulting in loss of fixed inorganic nitrogen in the marine environment. Ladderane lipids, membrane lipids unique to anammox bacteria, have been used as markers for the detection of anammox in marine settings. However, the fate of ladderane lipids after sediment burial and maturation is unknown. In this study, anammox bacterial cell material was artificially matured by hydrous pyrolysis at constant temperatures ranging from 120 to 365 ??C for 72 h to study the stability of ladderane lipids during progressive dia- and catagenesis. HPLC-MS/MS analysis revealed that structural alterations of ladderane lipids already occurred at 120 ??C. At temperatures >140 ??C, ladderane lipids were absent and only more thermally stable products could be detected, i.e., ladderane derivatives in which some of the cyclobutane rings were opened. These diagenetic products of ladderane lipids were still detectable up to temperatures of 260 ??C using GC-MS. Thus, ladderane lipids are unlikely to occur in ancient sediments and sedimentary rocks, but specific diagenetic products of ladderane lipids will likely be present in sediments and sedimentary rocks of relatively low maturity (i.e., C31 hopane 22S/(22S + 22R) ratio 0.5). ?? 2008 Elsevier Ltd.

Jaeschke, A.; Lewan, M.D.; Hopmans, E.C.; Schouten, S.; Sinninghe, Damste J.S.

2008-01-01

373

Polar Lipids of Burkholderia pseudomallei Induce Different Host Immune Responses  

PubMed Central

Melioidosis is a disease in tropical and subtropical regions of the world that is caused by Burkholderia pseudomallei. In endemic regions the disease occurs primarily in humans and goats. In the present study, we used the goat as a model to dissect the polar lipids of B. pseudomallei to identify lipid molecules that could be used for adjuvants/vaccines or as diagnostic tools. We showed that the lipidome of B. pseudomallei and its fractions contain several polar lipids with the capacity to elicit different immune responses in goats, namely rhamnolipids and ornithine lipids which induced IFN-?, whereas phospholipids and an undefined polar lipid induced strong IL-10 secretion in CD4+ T cells. Autologous T cells co-cultured with caprine dendritic cells (cDCs) and polar lipids of B. pseudomallei proliferated and up-regulated the expression of CD25 (IL-2 receptor) molecules. Furthermore, we demonstrated that polar lipids were able to up-regulate CD1w2 antigen expression in cDCs derived from peripheral blood monocytes. Interestingly, the same polar lipids had only little effect on the expression of MHC class II DR antigens in the same caprine dendritic cells. Finally, antibody blocking of the CD1w2 molecules on cDCs resulted in decreased expression for IFN-? by CD4+ T cells. Altogether, these results showed that polar lipids of B. pseudomallei are recognized by the caprine immune system and that their recognition is primarily mediated by the CD1 antigen cluster. PMID:24260378

Gonzalez-Juarrero, Mercedes; Mima, Naoko; Trunck, Lily A.; Schweizer, Herbert P.; Bowen, Richard A.; Dascher, Kyle; Mwangi, Waithaka; Eckstein, Torsten M.

2013-01-01

374

Role of ABC transporters in lipid transport and human disease  

PubMed Central

Almost half of the 48 human ATP binding cassette (ABC) transporter proteins are thought to facilitate the ATP-dependent translocation of lipids or lipid-related compounds. Such substrates include cholesterol, plant sterols, bile acids, phospholipids and sphingolipids. Mutations in a substantial number of the 48 human ABC transporters have been linked to human disease. Indeed the finding that 12 diseases have been associated with abnormal lipid transport and/or homeostasis, demonstrates the importance of this family of transporters in cell physiology. This review highlights the role of ABC transporters in lipid transport and movement, in addition to discussing their roles in cellular homeostasis and inherited disorders. PMID:23415156

Tarling, Elizabeth J.; de Aguiar Vallim, Thomas Q.; Edwards, Peter A.

2013-01-01

375

Protein-induced bilayer perturbations: Lipid ordering and hydrophobic coupling  

SciTech Connect

The host lipid bilayer is increasingly being recognized as an important non-specific regulator of membrane protein function. Despite considerable progress the interplay between hydrophobic coupling and lipid ordering is still elusive. We use electron spin resonance (ESR) to study the interaction between the model protein gramicidin and lipid bilayers of varying thickness. The free energy of the interaction is up to -6 kJ/mol; thus not strongly favored over lipid-lipid interactions. Incorporation of gramicidin results in increased order parameters with increased protein concentration and hydrophobic mismatch. Our findings also show that at high protein:lipid ratios the lipids are motionally restricted but not completely immobilized. Both exchange on and off rate values for the lipid {r_reversible} gramicidin interaction are lowest at optimal hydrophobic matching. Hydrophobic mismatch of few A results in up to 10-fold increased exchange rates as compared to the 'optimal' match situation pointing to the regulatory role of hydrophobic coupling in lipid-protein interactions.

Petersen, Frederic N.R.; Laursen, Ib; Bohr, Henrik [Quantum Protein Center, Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)] [Quantum Protein Center, Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Nielsen, Claus Helix, E-mail: claus.nielsen@fysik.dtu.dk [Quantum Protein Center, Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Aquaporin A/S, Diplomvej 377, DK-2800 Kgs. Lyngby (Denmark)

2009-10-02

376

Designer lipids for drug delivery: from heads to tails.  

PubMed

For four decades, liposomes composed of both naturally occurring and synthetic lipids have been investigated as delivery vehicles for low molecular weight and macromolecular drugs. These studies paved the way for the clinical and commercial success of a number of liposomal drugs, each of which required a tailored formulation; one liposome size does not fit all drugs! Instead, the physicochemical properties of the liposome must be matched to the pharmacology of the drug. An extensive biophysical literature demonstrates that varying lipid composition can influence the size, membrane stability, in vivo interactions, and drug release properties of a liposome. In this review we focus on recently described synthetic lipid headgroups, linkers and hydrophobic domains that can provide control over the intermolecular forces, phase preference, and macroscopic behavior of liposomes. These synthetic lipids further our understanding of lipid biophysics, promote targeted drug delivery and improve liposome stability. We further highlight the immune reactivity of novel synthetic headgroups as a key design consideration. For instance it was originally thought that synthetic PEGylated lipids were immunologically inert; however, it's been observed that under certain conditions PEGylated lipids induce humoral immunity. Such immune activation may be a limitation to the use of other engineered lipid headgroups for drug delivery. In addition to the potential immunogenicity of engineered lipids, future investigations on liposome drugs in vivo should pay particular attention to the location and dynamics of payload release. PMID:24816069

Kohli, Aditya G; Kierstead, Paul H; Venditto, Vincent J; Walsh, Colin L; Szoka, Francis C

2014-09-28

377

Histochemical evidence for lipid A (endotoxin) in eukaryote chloroplasts.  

PubMed

Lipopolysaccharide (LPS) (a.k.a., endotoxin) is an essential component of the outer leaflet of the outer membrane of gram-negative bacteria and is a potent activator of the innate immune system of animals. Lipid A, the glycolipid core of LPS, is the agent responsible for disease and death from gram-negative sepsis, an important cause of human mortality and morbidity. Although it is generally accepted that lipid A is restricted to the prokaryotes, recent efforts to purify molecules from green algae with structural features unique to lipid A have met with success. Furthermore, the vascular plant Arabidopsis thaliana has been found to contain genes that encode all of the enzymes of the biosynthetic pathway for lipid A. It is not known whether vascular plants synthesize lipid A or where lipid A might be located in the tissues. For the present study, we used affinity reagents for lipid A to probe green alga and tissues of the garden pea for a light microscopic localization of lipid A in these eukaryote cells. We find staining for lipid A in free-living and endosymbiotic green algae and in the chloroplasts of vascular plants, indicating that this molecule is not restricted to prokaryotes, but is found also in select eukaryotes. PMID:16935939

Armstrong, Margaret T; Theg, Steven M; Braun, Nikolai; Wainwright, Norman; Pardy, R L; Armstrong, Peter B

2006-10-01

378

Emerging methodologies to investigate lipid–protein interactions  

PubMed Central

Cellular membranes are composed of hundreds of different lipids, ion channels, receptors and scaffolding complexes that act as signalling and trafficking platforms for processes fundamental to life. Cellular signalling and membrane trafficking are often regulated by peripheral proteins, which reversibly interact with lipid molecules in highly regulated spatial and temporal fashions. In most cases, one or more modular lipid-binding domain(s) mediate recruitment of peripheral proteins to specific cellular membranes. These domains, of which more than 10 have been identified since 1989, harbour structurally selective lipid-binding sites. Traditional in vitro and in vivo studies have elucidated how these domains coordinate their cognate lipids and thus how the parent proteins associate with membranes. Cellular activities of peripheral proteins and subsequent physiological processes depend upon lipid binding affinities and selectivity. Thus, the development of novel sensitive and quantitative tools is essential in furthering our understanding of the function and regulation of these proteins. As this field expands into new areas such as computational biology, cellular lipid mapping, single molecule imaging, and lipidomics, there is an urgent need to integrate technologies to detail the molecular architecture and mechanisms of lipid signalling. This review surveys emerging cellular and in vitro approaches for studying protein–lipid interactions and provides perspective on how integration of methodologies directs the future development of the field. PMID:22327461

Scott, Jordan L.; Musselman, Catherine A.; Adu-Gyamfi, Emmanuel; Kutateladze, Tatiana G.

2013-01-01

379

Microalgal lipid droplets: composition, diversity, biogenesis and functions.  

PubMed

Lipid droplet is the major site of neutral lipid storage in eukaryotic cells, and increasing evidence show its involvement in numerous cellular processes such as lipid homeostasis, signaling, trafficking and inter-organelle communications. Although the biogenesis, structure, and functions of lipid droplets have been well documented for seeds of vascular plants, mammalian adipose tissues, insects and yeasts, relative little is known about lipid droplets in microalgae. Over the past 5 years, the growing interest of microalgae as a platform for biofuel, green chemicals or value-added polyunsaturated fatty acid production has brought algal lipid droplets into spotlight. Studies conducted on the green microalga Chlamydomonas reinhardtii and other model microalgae such as Haematococcus and Nannochloropsis species have led to the identification of proteins associated with lipid droplets, which include putative structural proteins different from plant oleosins and animal perilipins, as well as candidate proteins for lipid biosynthesis, mobilization, trafficking and homeostasis. Biochemical and microscopy studies have also started to shed light on the role of chloroplasts in the biogenesis of lipid droplets in Chlamydomonas. PMID:25433857

Goold, Hugh; Beisson, Fred; Peltier, Gilles; Li-Beisson, Yonghua

2014-11-30

380

Epidermal lipid in several cetacean species: ultrastructural observations.  

PubMed

The ultrastructure of the skin of four cetacean species, bottlenose dolphin (Tursiops truncatus) long-finned pilot whale (Globicephala melaena), humpback whale (Megaptera novaeangliae), and fin whale (Balaenoptera physalus) was investigated with particular reference to epidermal lipid. It has already been established that massive lipid reservoirs exist in whales, that the biochemical structures of cetacean lipids are unique, and that unusual intracellular lipid droplets appear in the epidermis. We report here some novel findings on scanning electron microscopic morphology of epidermal lipid, and on its ultrastructural morphology in general and specialized integumentary sites, including species not previously investigated. The intracellular epidermal lipid droplets were more extensive than lamellar body-derived intercellular lipid which is within the interstices of stratum externum cells. The intracellular droplets were spherical, highly variable in size ranging from 0.24 micron to 3.0 microns in diameter, appeared singly or were aggregated in cytoplasmic cavitations, and often were closely associated with epidermal cell nuclei. Evidence for exocytosis of the intracellular droplets was not observed. Significant numbers of intracellular lipid droplets are not observed in the epidermis of terrestrial mammals, so their presence is one of several aquatic specializations of the cetacean integument. Its full significance remains obscure, but it is more probably associated with epidermal cell metabolism than with secretion of lipid. PMID:8250278

Pfeiffer, C J; Jones, F M

1993-09-01

381

Coupled Diffusion in Lipid Bilayers upon Close Approach.  

PubMed

Biomembrane interfaces create regions of slowed water dynamics in their vicinity. When two lipid bilayers come together, this effect is further accentuated, and the associated slowdown can affect the dynamics of larger-scale processes such as membrane fusion. We have used molecular dynamics simulations to examine how lipid and water dynamics are affected as two lipid bilayers approach each other. These two interacting fluid systems, lipid and water, both slow and become coupled when the lipid membranes are separated by a thin water layer. We show in particular that the water dynamics become glassy, and diffusion of lipids in the apposed leaflets becomes coupled across the water layer, while the "outer" leaflets remain unaffected. This dynamic coupling between bilayers appears mediated by lipid-water-lipid hydrogen bonding, as it occurs at bilayer separations where water-lipid hydrogen bonds become more common than water-water hydrogen bonds. We further show that such coupling occurs in simulations of vesicle-vesicle fusion prior to the fusion event itself. Such altered dynamics at membrane-membrane interfaces may both stabilize the interfacial contact and slow fusion stalk formation within the interface region. PMID:25535654

Pronk, Sander; Lindahl, Erik; Kasson, Peter M

2015-01-21

382

The Role of Lipids on Sorption Characteristics of Freshwater and Wastewater-Irrigated Soils  

Microsoft Academic Search

The soil lipid fraction can play an important role in the sorption of organic compounds. In this study, the impact of the lipid fraction of freshwater- and wastewater-irrigated soils on the sorption of non- and relatively polar compounds was assessed. Lipid analyses revealed a clear difference between the two lipid fractions. The lipid extract from the wastewater-irrigated soil was consistent

Yaron Drori; Buuan Lam; Andre Simpson; Zeev Aizenshtat; Benny Chefetz

2006-01-01

383

Mechanism of alamethicin insertion into lipid bilayers.  

PubMed Central

Alamethicin adsorbs on the membrane surface at low peptide concentrations. However, above a critical peptide-to-lipid ratio (P/L), a fraction of the peptide molecules insert in the membrane. This critical ratio is lipid dependent. For diphytanoyl phosphatidylcholine it is about 1/40. At even higher concentrations P/L > or = 1/15, all of the alamethicin inserts into the membrane and forms well-defined pores as detected by neutron in-plane scattering. A previous x-ray diffraction measurement showed that alamethicin adsorbed on the surface has the effect of thinning the bilayer in proportion to the peptide concentration. A theoretical study showed that the energy cost of membrane thinning can indeed lead to peptide insertion. This paper extends the previous studies to the high-concentration region P/L > 1/40. X-ray diffraction shows that the bilayer thickness increases with the peptide concentration for P/L > 1/23 as the insertion approaches 100%. The thickness change with the percentage of insertion is consistent with the assumption that the hydrocarbon region of the bilayer matches the hydrophobic region of the inserted peptide. The elastic energy of a lipid bilayer including both adsorption and insertion of peptide is discussed. The Gibbs free energy is calculated as a function of P/L and the percentage of insertion phi in a simplified one-dimensional model. The model exhibits an insertion phase transition in qualitative agreement with the data. We conclude that the membrane deformation energy is the major driving force for the alamethicin insertion transition. Images FIGURE 1 PMID:8913604

He, K; Ludtke, S J; Heller, W T; Huang, H W

1996-01-01

384

Improved high-performance liquid chromatographic method for the separation and quantification of lipid classes: application to fish lipids.  

PubMed

An improved straight-phase HPLC method for the separation and quantification of lipid classes is described. Two binary gradient solvent systems were used, one for polar and one for neutral lipids, and detection was performed with a light-scattering detector. The developed HPLC methods were highly reproducible and allowed base-line separation of all investigated polar lipid classes (phosphatidic acid, diphosphatidylglycerol. phosphatidylethanolamine, phosphatidylcholine, sphingomyelin, phosphatidylserine, phosphatidylinositol and lysophosphatidylcholine) and neutral lipid classes (triacylglycerol, free fatty acid, diacylglycerol, cholesterol and monoacylglycerol) except of cholesterol ester and wax ester. Application of the chromatographic systems demonstrated that the methods are suitable for quantitative analysis of the major lipid classes present in lipid extracts from livers and eggs of Atlantic salmon (Salmo salar). PMID:9448057

Silversand, C; Haux, C

1997-12-01

385

Approaches toward functional fluid supported lipid bilayers  

NASA Astrophysics Data System (ADS)

Planar supported lipid bilayers (PSLBs) have attracted immense interest for their properties as model cell membranes and for potential applications in biosensors and lab-on-a-chip devices. Our study covers three aspects of the construction, characterization, and application of functional PSLBs. First, a combination of micro-fabrication, the Langmuir-Blodgett (LB) technique, and fusion of extruded small unilamellar vesicle (E-SUVs) in sequence was used to create polymer-cushioned PSLBs in a microarray format. Random lipo-glycocopolymer mixed with L-alpha-phosphatidylcholine (egg PC) was compressed at the air-water interface and transferred onto the photoresist-patterned substrate by the LB technique to achieve spatially directed deposition. Construction of planar bilayers in an aqueous environment was subsequently completed by vesicle fusion. Epifluorescence microscopy, fluorescence recovery after photobleaching (FRAP), and electrophoresis-relaxation were employed to examine the resulting patterns as well as to verify the two-dimensional mobility of the supported membrane systems. This approach could possibly provide a useful route to create functional arrays of polymer-supported lipid bilayers. Second, we report the formation of fluid planar biomembranes on hydrophilic silica aerogels and xerogels. When the aerogel/xerogel was pre-hydrated and then allowed to incubate in egg PC E-SUV solution, lipid bilayers were formed due to the favorable interaction of vesicles with the hydroxyl-abundant silica surface. FRAP was used to determine the lateral diffusivity of membranes on aerogels. Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to monitor the kinetics of the irreversible adsorption and fusion of vesicles into bilayers on xerogel thin films. Finally, we compared the formation of PSLBs with and without incorporation of monosialoganglioside GM1 (GM1) as the antigen for in situ antibody binding. Quantifiable differences were observed in the transformation of egg PC E-SUVs containing 0 mol%, 2 mol%, and 5 mol% GM1 to PSLBs by vesicle fusion on thermally evaporated silicon dioxide surfaces, as monitored by the QCM-D technique. FRAP was utilized to verify the retained, albeit reduced, fluidity of the GM1-containing PSLBs. Our analysis of rabbit serum antibodies binding to GM1 demonstrates this platform can be used to test for the presence of anti-lipid antibodies in serum.

Weng, Kevin Chun-I.

386

[Advance in glycolipid biosurfactants--mannosylerythritol lipids].  

PubMed

Mannosylerythritol lipids (MELs), mainly produced by Ustilago and Pseudozyma, are surface active compounds that belong to the glycolipid class of biosurfactants. MELs have potential application in food, pharmaceutical and cosmetics industries due to their excellent surface activities and other peculiar bioactivities. In recent years, the research field of MELs has regained much attention abroad. However, MELs are rarely studied in China. In this review, the producing microorganisms and production conditions, diverse structures, biochemical properties, structure-function relationship and biosynthetic pathways of MELs are described. Some research problems and prospects are summarized and discussed as well. PMID:24409686

Fan, Linlin; Zhang, Jun; Cai, Jin; Dong, Yachen; Xu, Tengyang; He, Guoqing; Chen, Qihe

2013-09-01

387

Effect of Rowachol on biliary lipid secretion and serum lipids in normal volunteers.  

PubMed

The effect of Rowachol (200 mg tid), an essential oil preparation, on biliary lipid secretion and serum lipids was measured in six healthy male volunteers before and after four weeks of treatment. Biliary cholesterol and phospholipid secretion increased significantly from 113 +/- 36 (SD) mumol/h to 155 +/- 52 mumol/h (p less than 0.05) and from 409 +/- 145 mumol/h to 587 +/- 185 mumol/h (p less than 0.05), respectively. Bile acid secretion increased from 1519 +/- 662 mumol/h to 2287 +/- 1175 mumol/h (p greater than 0.05 and greater than 0.10). This marked increase in biliary lipid secretion was not followed by a change in molar composition of biliary lipids and lithogenicity of bile. Serum cholesterol and triglycerides declined from 4.9 mmol/l to 4.1 mmol/l (p less than 0.05) and from 1.2 mmol/l to 0.9 mmol/l (p less than 0.05) respectively. The ratio of high-density-lipoprotein cholesterol to total cholesterol increased from 0.22 to 0.31 (p less than 0.05). Although it has been shown previously that Rowachol could dissolve cholesterol gall stones the present results indicate that Rowachol alone has only weak litholytic properties, at least in normal volunteers, but might have several advantages when combined with chenodeoxycholic or ursodeoxycholic acid. PMID:3965364

Leiss, O; von Bergmann, K

1985-01-01

388

Phase separation of lipid microdomains controlled by polymerized lipid bilayer matrices.  

PubMed

We developed a micropatterned model biological membrane on a solid substrate that can induce phase separation of lipid microdomains in a designed geometry. Micropatterned lipid bilayers were generated by the photolithographic polymerization of a diacetylene phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DiynePC). By changing the UV dose for the photopolymerization, we could modulate the coverage of the surface by the polymeric bilayer domains. After removing nonpolymerized DiynePC, natural phospholipid membranes were incorporated into the micropatterned polymeric bilayer matrix by a self-assembly process (vesicle fusion). As we incorporated a ternary lipid mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), sphingomyelin (SM), and cholesterol (Chol) (1:1:1), liquid ordered domains (Lo: rich in SM and Chol) were accumulated in the polymer free regions, whereas liquid disordered domains (Ld: rich in DOPC) preferentially participated into the partially polymeric bilayer regions. It was postulated that Ld domains preferentially came in contact with the polymeric bilayer boundaries because of their lower elastic moduli and a smaller thickness mismatch at the boundary. The effect of polymeric bilayer matrix to hinder the size growth of Lo domains should also be playing an important role. The controlled phase separation should open new possibilities to locally concentrate membrane proteins and other nanometer-sized materials on the substrate by associating them with the lipid microdomains. PMID:20020734

Okazaki, Takashi; Tatsu, Yoshiro; Morigaki, Kenichi

2010-03-16

389

The Protein and Lipid Composition of Arterial Elastin and Its Relationship to Lipid Accumulation in the Atherosclerotic Plaque  

PubMed Central

Elastin preparations from intimal layers and the media of normal and atherosclerotic human aortae were analyzed for protein and lipid content. In atherosclerotic aortae, elastin from plaques was compared with elastin from adjacent normal appearing areas of the same aorta. Arterial elastin purified by alkaline extraction appeared to be a protein-lipid complex containing free and ester cholesterol, phospholipids, and triglycerides. The lipid component of normal arterial elastin was small (1-2%). With increasing severity of atherosclerosis, there was a progressive accumulation of lipid in intimal elastin from plaques, reaching a mean lipid content of 37% in severe plaques. The increase in the lipid content of plaque elastic preparations was mainly due to large increases in cholesterol, over 80% of which was cholesteryl ester. This deposition of cholesterol in plaque elastin accounted for 20-34% of the total cholesterol content of the plaque. The increased lipid deposition in plaque elastin was associated with alterations in the amino acid composition of plaque elastin. In elastin from plaque intima, the following polar amino acids were increased significantly: aspartic acid, threonine, serine, glutamic acid, lysine, histidine, and arginine; whereas, cross-linking amino acids: desmosine, isodesmosine, and lysinonorleucine were decreased significantly. The amino acid and lipid composition of elastin from normal appearing aortic areas was comparable to that of normal arterial elastin except for intimal elastin directly adjacent to and medial elastin directly below the most severe plaques. The data indicate that the focal lipid deposition in early atherosclerotic plaques is due to a large extent to lipid accumulations in altered elastin protein of localized intimal areas. Continued lipid deposition in altered elastin appears to contribute substantially to the progressive lipid accumulation in the plaque. The study suggests that elastin of intimal elastic membranes may play an important role in the pathogenesis and progression of atherosclerosis. PMID:5097573

Kramsch, Dieter M.; Franzblau, Carl; Hollander, William

1971-01-01

390

Lipid composition of beef brain, beef liver, and the sea anemone: Two approaches to quantitative fractionation of complex lipid mixtures  

Microsoft Academic Search

Two new schemes for fractionation of complex lipid mixtures are presented. Their use for the study of lipids of beef brain,\\u000a beef liver, and the sea anemone are described. Apparatus and techniques for working in an inert atmosphere, evaporation of\\u000a solutions in the cold under nitrogen, use of infrared spectroscopy for examination of lipids and their hydrolysis products,\\u000a preparation and

George Rouser; Gene Kritchevsky; Dorothy Heller; Ellen Lieber

1963-01-01

391

Lipid changes in maturing oil-bearing plants. III. Changes in lipid classes in flax and safflower oils  

Microsoft Academic Search

Seeds from Raja flax and Indian safflower were collected at increasing stages of maturity and the free lipid extracted from\\u000a them with hexane. The true lipid material obtained in this manner was separated into lipid classes by silicic acid column\\u000a chromatography using a diethyl ether-hexane gradient and methanol for the phospholipids. Thin-layer chromatography was used\\u000a to establish the homogeneity of

Mary E. McKillican; R. P. A. Sims

1963-01-01

392

Effectiveness of Omega-3 Supplement on Lipid Profile and Lipid Peroxidation in Kidney Allograft Recipients  

PubMed Central

Background Omega-3 fatty acids carry major roles in mediating inflammation, immune response, lipid peroxidation and lipoprotein metabolism. Diversity of health benefits have been attributed to dietary supplementation with omega-3 fatty acids in transplant and nontransplant settings. Several studies in renal transplantation have suggested that supplementation with omega-3 fatty acids may lead to significant clinical benefits. However, the extents of these benefits are variable and published data had not coincided with positive findings. Objectives The aim of this study was to evaluate the effectiveness of omega-3 supplementation on the lipid profile and lipid peroxidation in patients underwent kidney transplant. Patients and Methods Thirty cases had been selected with stable allograft function following at least six months of transplantation. The serum levels of lipids including triglyceride, low density lipoprotein (LDL), high density lipoprotein (HDL), very low density lipoprotein (VLDL), total cholesterol and indices of lipid peroxidation (malondialdehyde and APO a1) were measured by biochemical techniques at the baseline. Two months following prescription of oral omega-3 (3 g/day), the biochemical measurements were repeated and the differences were analyzed. Results Of thirty patients, 12 were male and 18 were female with the mean age of 45.3 ± 13.0 (18-65) years. At the baseline, the serum levels of MDA and APO B were 3.5 ± 1.3 and 148.3 ± 20.4 ng/dL respectively. At the end of two months following intervention, they were 3.2 ± 1.2 and 145.7 ± 19.0 ng/dL, respectively (P > 0.05). Correspondingly, at the baseline the serum levels of triglyceride, LDL, VLDL and total cholesterol were 171.1 ± 58.7, 106.9 ± 31.8, 42.2 ± 4.0, 145.7 ± 33.2 and 181.2 ± 35.1 mg/dL and after intervention they were 162.4 ± 82.5, 99.4 ± 35.1, 44.6 ± 6.3, 140.3 ± 33.1 and 170.9 ± 38.3 mg/dL, respectively (P > 0.05). There was no significant difference between the males and females in this instance. Conclusions Our results seem to indicate that oral omega-3 may promote the lipid profile and indices of lipid peroxidation in patients following kidney transplantation however extents of these effects are not significant. PMID:24282793

Tayebi Khosroshahi, Hamid; Mousavi Toomatari, Seyed Ehsan; Akhavan Salamat, Sara; Davar Moin, Giti; Najafi Khosroshahi, Sattar

2013-01-01

393

Biological activity of synthetic phosphonooxyethyl analogs of lipid A and lipid A partial structures.  

PubMed Central

We investigated the biological activity of four new synthetic analogs of lipid A, termed PE-1, PE-2, PE-3, and PE-4. All compounds contain an alpha-oxyethyl-linked (-O-CH2-CH2-) phosphoryl group in position 1 of the reducing glucosaminyl residue (GlcN I) of lipid A. PE-1 is a hexaacylated analog of Escherichia coli lipid A (compound 506). PE-2 differs from PE-1 in carrying two myristic acid residues at GlcN I. PE-3 has the same acylation pattern as PE-2, but GlcN I is present in the beta anomeric form. Finally, PE-4 represents an analog of tetraacyl precursor Ia (compound 406). Structure-activity relationships of these compounds were determined by measuring their capacity to induce tumor necrosis factor alpha, interleukin 1, and interleukin 6 release by human mononuclear cells and to cause mitogenicity of murine spleen cells. The results show that replacement of the glycosidic phosphoryl residue by a phosphonooxyethyl group had no substantial effect on the biological activity of compounds. However, the anomeric configuration of GlcN I was found to be of great biological relevance, as, in general, the alpha anomer (PE-2) expressed high activity, and the beta anomer (PE-3) expressed low mediator-inducing and mitogenic activity. The absence of the 3-hydroxyl groups within the acyl residues at GlcN I in PE-2 was found to only slightly affect the induction of monokines in human mononuclear cells compared with that of PE-1 or lipid A (506). These stable 1-phosphonooxyethyl analogs of lipid A may be candidates in the development of immunomodulators for the treatment of systemic endotoxicosis. PMID:1639498

Ulmer, A J; Heine, H; Feist, W; Kusumoto, S; Kusama, T; Brade, H; Schade, U; Rietschel, E T; Flad, H D

1992-01-01

394

PPAR-? activation by Tityus serrulatus venom regulates lipid body formation and lipid mediator production.  

PubMed

Tityus serrulatus venom (TsV) consists of numerous peptides with different physiological and pharmacological activities. Studies have shown that scorpion venom increases pro-inflammatory cytokine production, contributing to immunological imbalance, multiple organ dysfunction, and patient death. We have previously demonstrated that TsV is a venom-associated molecular pattern (VAMP) recognized by TLRs inducing intense inflammatory reaction through the production of pro-inflammatory cytokines and arachidonic acid-derived lipid mediators prostaglandin (PG)E2 and leukotriene (LT)B4. Lipid bodies (LBs) are potential sites for eicosanoid production by inflammatory cells. Moreover, recent studies have shown that the peroxisome proliferator-activated receptor gamma (PPAR-?) is implicated in LB formation and acts as an important modulator of lipid metabolism during inflammation. In this study, we used murine macrophages to evaluate whether the LB formation induced by TsV after TLR recognition correlates with lipid mediator generation by macrophages and if it occurs through PPAR-? activation. We demonstrate that TsV acts through TLR2 and TLR4 stimulation and PPAR-? activation to induce LB formation and generation of PGE2 and LTB4. Our data also show that PPAR-? negatively regulates the pro-inflammatory NF-?B transcription factor. Based on these results, we suggest that during envenomation, LBs constitute functional organelles for lipid mediator production through signaling pathways that depend on cell surface and nuclear receptors. These findings point to the inflammatory mechanisms that might also be triggered during human envenomation by TsV. PMID:25450800

Zoccal, Karina Furlani; Paula-Silva, Francisco Wanderley Garcia; Bitencourt, Claudia da Silva; Sorgi, Carlos Artério; Bordon, Karla de Castro Figueiredo; Arantes, Eliane Candiani; Faccioli, Lúcia Helena

2015-01-01

395

Genetic Analysis of Arabidopsis Mutants Impaired in Plastid Lipid Import Reveals a Role of Membrane Lipids in Chloroplast Division  

SciTech Connect

The biogenesis of photosynthetic membranes in plants relies largely on lipid import from the endoplasmic reticulum (ER) and this lipid transport process is mediated by TGD proteins in Arabidopsis. Such a dependency of chloroplast biogenesis on ER-to-plastid lipid transport was recently exemplified by analyzing double mutants between tgd1-1 or tgd4-3 and fad6 mutants. The fad6 mutants are defective in the desaturation of membrane lipids in chloroplasts and therefore dependent on import of polyunsaturated lipid precursors from the ER for constructing a competent thylakoid membrane system. In support of a critical role of TGD proteins in ER-to-plastid lipid trafficking, we showed that the introduction of the tgd mutations into fad6 mutant backgrounds led to drastic reductions in relative amounts of thylakoid lipids. Moreover, the tgd1-1 fad6 and tgd4-3 fad6 double mutants were deficient in polyunsaturated fatty acids in chloroplast membrane lipids, and severely compromised in the biogenesis of photosynthetic membrane systems. Here we report that these double mutants are severely impaired in chloroplast division. The possible role of membrane lipids in chloroplast division is discussed.

Fan, J.; Xu, C.

2011-03-01

396

Lipid profiling by electrospray ionization tandem mass spectrometry and the identification of lipid phosphorylation by kinases in potato stolons  

PubMed Central

There is limited information about the involvement of lipids and esterified fatty acids in signaling pathways during plant development. The purpose of this study was to evaluate the lipid composition and molecular species of potato (Solanum tuberosum L., cv. Spunta) stolons and to identify phosphorylated lipids in the first two developmental stages of tuber formation. Lipid profiling was determined using ESI-MS/MS, a useful method for the determination of the biosynthesis and catabolism of lipids based on their fatty acid composition. The most prevalent compound identified in this study was phosphatidic acid (PA); digalactosyldiacylglycerol (DGDG) was the second most abundant compound. A 34:2 species was identified in PA, phosphatidylcholine (PC), phosphatidylinositol (PI), and phosphatidylethanolamine (PE). The identification of lipid phosphorylation by kinases was revealed by the presence of the phosphorylated lipids. PA was metabolized to diacylglycerol pyrophosphate (DGPP) by phosphatidic acid kinase (PAK). This work establishes a correlation between lipid fatty acid composition and lipid metabolism enzymes at the beginning of tuber formation and is the first report of PAK activity in the early events of potato tuber formation. PMID:22142228

Cenzano, Ana M.; Cantoro, Renata; Teresa Hernandez-Sotomayor, S. M.; Abdala, Guillermina I.; Racagni, Graciela E.

2013-01-01

397

Oral mucosal lipids are antibacterial against Porphyromonas gingivalis, induce ultrastructural damage, and alter bacterial lipid and protein compositions  

PubMed Central

Oral mucosal and salivary lipids exhibit potent antimicrobial activity for a variety of Gram-positive and Gram-negative bacteria; however, little is known about their spectrum of antimicrobial activity or mechanisms of action against oral bacteria. In this study, we examine the activity of two fatty acids and three sphingoid bases against Porphyromonas gingivalis, an important colonizer of the oral cavity implicated in periodontitis. Minimal inhibitory concentrations, minimal bactericidal concentrations, and kill kinetics revealed variable, but potent, activity of oral mucosal and salivary lipids against P. gingivalis, indicating that lipid structure may be an important determinant in lipid mechanisms of activity against bacteria, although specific components of bacterial membranes are also likely important. Electron micrographs showed ultrastructural damage induced by sapienic acid and phytosphingosine and confirmed disruption of the bacterial plasma membrane. This information, coupled with the association of treatment lipids with P. gingivalis lipids revealed via thin layer chromatography, suggests that the plasma membrane is a likely target of lipid antibacterial activity. Utilizing a combination of two-dimensional in-gel electrophoresis and Western blot followed by mass spectroscopy and N-terminus degradation sequencing we also show that treatment with sapienic acid induces upregulation of a set of proteins comprising a unique P. gingivalis stress response, including proteins important in fatty acid biosynthesis, metabolism and energy production, protein processing, cell adhesion and virulence. Prophylactic or therapeutic lipid treatments may be beneficial for intervention of infection by supplementing the natural immune function of endogenous lipids on mucosal surfaces. PMID:23867843

Fischer, Carol L; Walters, Katherine S; Drake, David R; Dawson, Deborah V; Blanchette, Derek R; Brogden, Kim A; Wertz, Philip W

2013-01-01

398

Factors influencing particulate lipid production in the East Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Extensive analyses of particulate lipids and lipid classes were conducted to gain insight into lipid production and related factors along the biogeochemical provinces of the Eastern Atlantic Ocean. Data are supported by particulate organic carbon (POC), chlorophyll a (Chl a), phaeopigments, Chl a concentrations and carbon content of eukaryotic micro-, nano- and picophytoplankton, including cell abundances for the latter two and for cyanobacteria and prokaryotic heterotrophs. We focused on the productive ocean surface (2 m depth and deep Chl a maximum (DCM). Samples from the deep ocean provided information about the relative reactivity and preservation potential of particular lipid classes. Surface and DCM particulate lipid concentrations (3.5-29.4 ?g L-1) were higher than in samples from deep waters (3.2-9.3 ?g L-1) where an increased contribution to the POC pool was observed. The highest lipid concentrations were measured in high latitude temperate waters and in the North Atlantic Tropical Gyral Province (13-25°N). Factors responsible for the enhanced lipid synthesis in the eastern Atlantic appeared to be phytoplankton size (micro, nano, pico) and the low nutrient status with microphytoplankton having the most expressed influence in the surface and eukaryotic nano- and picophytoplankton in the DCM layer. Higher lipid to Chl a ratios suggest enhanced lipid biosynthesis in the nutrient poorer regions. The various lipid classes pointed to possible mechanisms of phytoplankton adaptation to the nutritional conditions. Thus, it is likely that adaptation comprises the replacement of membrane phospholipids by non-phosphorus containing glycolipids under low phosphorus conditions. The qualitative and quantitative lipid compositions revealed that phospholipids were the most degradable lipids, and their occurrence decreased with increasing depth. In contrast, wax esters, possibly originating from zooplankton, survived downward transport probably due to the fast sinking rate of particles (fecal pellets). The important contribution of glycolipids in deep waters reflected their relatively stable nature and degradation resistance. A lipid-based proxy for the lipid degradative state (Lipolysis Index) suggests that many lipid classes were quite resistant to degradation even in the deep ocean.

Gašparovi?, B.; Frka, S.; Koch, B. P.; Zhu, Z. Y.; Bracher, A.; Lechtenfeld, O. J.; Neogi, S. B.; Lara, R. J.; Kattner, G.

2014-07-01

399

Lipid ion channels and the role of proteins.  

PubMed

In the absence of proteins, synthetic lipid membranes can display quantized conduction events for ions that are virtually indistinguishable from those of protein channels. The phenomenological similarities between typical conductances are striking: they are of equal order and show similar lifetime distributions and current histograms. They can include conduction bursts, flickering, and multistep conductance. Lipid channels can be gated by voltage and blocked by drugs. They respond to changes in lateral membrane tension and temperature. Thus, they behave like voltage-gated, temperature-gated, and mechano-sensitive protein channels, or like receptors. The similarity between lipid and protein channels poses an important problem for the interpretation of protein channel data. For example, the Hodgkin-Huxley theory for nerve pulse conduction requires a selective mechanism for the conduction of sodium and potassium ions. To this end, the lipid membrane must act both as a capacitor and as an insulator. Nonselective ion conductance by mechanisms other than the gated protein channels challenges the proposed mechanism for pulse propagation. Nevertheless, textbooks rarely describe the properties of the lipid membrane surrounding the proteins in their discussions of membrane models. These similarities lead to important questions: Do these similarities in lipid and protein channels result from a common mechanism, or are these similarities fortuitous? What distinguishes protein channels from lipid channels, if anything? In this Account, we document experimental and theoretical findings that show the similarity between lipid and protein channels. We discuss important cases where protein channel function strongly correlates with the properties of the lipid. Based on statistical thermodynamics simulations, we discuss how such correlations could come about. We suggest that proteins can act as catalysts for lipid channel formation and that this hypothesis can explain some of the unexplained correlations between protein and lipid membrane function. PMID:23902303

Mosgaard, Lars D; Heimburg, Thomas

2013-12-17

400

Lipid emulsions – Guidelines on Parenteral Nutrition, Chapter 6  

PubMed Central

The infusion of lipid emulsions allows a high energy supply, facilitates the prevention of high glucose infusion rates and is indispensable for the supply with essential fatty acids. The administration of lipid emulsions is recommended within ?7 days after starting PN (parenteral nutrition) to avoid deficiency of essential fatty acids. Low-fat PN with a high glucose intake increases the risk of hyperglycaemia. In parenterally fed patients with a tendency to hyperglycaemia, an increase in the lipid-glucose ratio should be considered. In critically ill patients the glucose infusion should not exceed 50% of energy intake. The use of lipid emulsions with a low phospholipid/triglyceride ratio is recommended and should be provided with the usual PN to prevent depletion of essential fatty acids, lower the risk of hyperglycaemia, and prevent hepatic steatosis. Biologically active vitamin E (?-tocopherol) should continuously be administered along with lipid emulsions to reduce lipid peroxidation. Parenteral lipids should provide about 25–40% of the parenteral non-protein energy supply. In certain situations (i.e. critically ill, respiratory insufficiency) a lipid intake of up to 50 or 60% of non-protein energy may be reasonable. The recommended daily dose for parenteral lipids in adults is 0.7–1.3 g triglycerides/kg body weight. Serum triglyceride concentrations should be monitored regularly with dosage reduction at levels >400 mg/dl (>4.6 mmol/l) and interruption of lipid infusion at levels >1000 mg/dl (>11.4 mmol/l). There is little evidence at this time that the choice of different available lipid emulsions affects clinical endpoints. PMID:20049078

Adolph, M.; Heller, A. R.; Koch, T.; Koletzko, B.; Kreymann, K. G.; Krohn, K.; Pscheidl, E.; Senkal, M.

2009-01-01

401

Crystallizing membrane proteins using lipidic bicelles  

PubMed Central

Crystallization of membrane proteins remains a significant challenge. For proteins resistant to the traditional approach of directly crystallizing from detergents, lipidic phase crystallization can be a powerful tool. Bicelles are an excellent medium for crystallizing membrane proteins in a lipidic environment. They can be described as bilayer discs formed by the mixture of a long-chain phospholipid and an amphiphile in an aqueous medium. Membrane proteins can be readily reconstituted into bicelles, where they are maintained in a native-like bilayer environment. Importantly, membrane proteins have been shown to be fully functional in bicelles under physiological conditions. Protein-bicelle mixtures can be manipulated with almost the same ease as detergent-solubilized membrane proteins, making bicelles compatible with standard equipment including high-throughput crystallization robots. A number of membrane proteins have now been successfully crystallized using the bicelle method, including bacteriorhodopsin, ?2 adrenergic receptor, voltage-dependent anion channel, xanthorhodopsin and rhomboid protease. Because of the success with a variety of membrane proteins and the ease of implementation, bicelles should be part of every membrane protein crystallographer's arsenal. PMID:21982781

Ujwal, Rachna; Bowie, James U.

2011-01-01

402

Crystallizing membrane proteins using lipidic bicelles.  

PubMed

Crystallization of membrane proteins remains a significant challenge. For proteins resistant to the traditional approach of directly crystallizing from detergents, lipidic phase crystallization can be a powerful tool. Bicelles are an excellent medium for crystallizing membrane proteins in a lipidic environment. They can be described as bilayer discs formed by the mixture of a long-chain phospholipid and an amphiphile in an aqueous medium. Membrane proteins can be readily reconstituted into bicelles, where they are maintained in a native-like bilayer environment. Importantly, membrane proteins have been shown to be fully functional in bicelles under physiological conditions. Protein-bicelle mixtures can be manipulated with almost the same ease as detergent-solubilized membrane proteins, making bicelles compatible with standard equipment including high-throughput crystallization robots. A number of membrane proteins have now been successfully crystallized using the bicelle method, including bacteriorhodopsin, ?2 adrenergic receptor, voltage-dependent anion channel, xanthorhodopsin and rhomboid protease. Because of the success with a variety of membrane proteins and the ease of implementation, bicelles should be a part of every membrane protein crystallographer's arsenal. PMID:21982781

Ujwal, Rachna; Bowie, James U

2011-12-01

403

Face the Fats The Biochemistry of Lipids  

NSDL National Science Digital Library

This clicker case introduces students to the biochemistry of lipids through the story of Pete, a college student who begins to consider his nutritional fat intake after watching a commercial for the cholesterol-lowering drug Vytorin. In this case, students learn to differentiate the chemical composition of steroids, phospholipids, and fats as well as how lipids affect our health, both in positive and negative ways. Additionally, students learn how trans fats are manufactured and why they can have negative health side-effects. The case is designed for use in an introductory biology course either for science majors or non-majors. It could potentially be further modified for use in an upper-level biochemistry or cell biology class. The case is called a clicker case because it combines the use of PowerPoint slides (~3.74MB) and student response systems ("clickers") with a case storyline and questions. The case could be modifed however for use without these technologies.

Rice, Nancy A.

2011-01-01

404

Structure of Cholesterol in Lipid Rafts  

NASA Astrophysics Data System (ADS)

Rafts, or functional domains, are transient nano-or mesoscopic structures in the plasma membrane and are thought to be essential for many cellular processes such as signal transduction, adhesion, trafficking, and lipid or protein sorting. Observations of these membrane heterogeneities have proven challenging, as they are thought to be both small and short lived. With a combination of coarse-grained molecular dynamics simulations and neutron diffraction using deuterium labeled cholesterol molecules, we observe raftlike structures and determine the ordering of the cholesterol molecules in binary cholesterol-containing lipid membranes. From coarse-grained computer simulations, heterogenous membranes structures were observed and characterized as small, ordered domains. Neutron diffraction was used to study the lateral structure of the cholesterol molecules. We find pairs of strongly bound cholesterol molecules in the liquid-disordered phase, in accordance with the umbrella model. Bragg peaks corresponding to ordering of the cholesterol molecules in the raftlike structures were observed and indexed by two different structures: a monoclinic structure of ordered cholesterol pairs of alternating direction in equilibrium with cholesterol plaques, i.e., triclinic cholesterol bilayers.

Toppozini, Laura; Meinhardt, Sebastian; Armstrong, Clare L.; Yamani, Zahra; Ku?erka, Norbert; Schmid, Friederike; Rheinstädter, Maikel C.

2014-11-01

405

Cognition, dopamine and bioactive lipids in schizophrenia  

PubMed Central

Schizophrenia is a remarkably complex disorder with a multitude of behavioral and biological perturbations. Cognitive deficits are a core feature of this disorder, and involve abnormalities across multiple domains, including memory, attention, and perception. The complexity of this debilitating illness has led to a view that the key to unraveling its pathophysiology lies in deconstructing the clinically-defined syndrome into pathophysiologically distinct intermediate phenotypes. Accumulating evidence suggests that one of these intermediate phenotypes may involve phospholipid signaling abnormalities, particularly in relation to arachidonic acid (AA). Our data show relationships between levels of AA and performance on tests of cognition for schizophrenia patients, with defects in AA signaling associated with deficits in cognition. Moreover, dopamine may moderate these relationships between AA and cognition. Taken together, cognitive deficits, dopaminergic neurotransmission, and bioactive lipids have emerged as related features of schizophrenia. Existing treatment options for cognitive deficits in schizophrenia do not specifically target lipid-derived signaling pathways; understanding these processes could inform efforts to identify novel targets for treatment innovation. PMID:21196378

Condray, Ruth; Yao, Jeffrey K.

2011-01-01

406

Structure of Cholesterol in Lipid Rafts.  

PubMed

Rafts, or functional domains, are transient nano-or mesoscopic structures in the plasma membrane and are thought to be essential for many cellular processes such as signal transduction, adhesion, trafficking, and lipid or protein sorting. Observations of these membrane heterogeneities have proven challenging, as they are thought to be both small and short lived. With a combination of coarse-grained molecular dynamics simulations and neutron diffraction using deuterium labeled cholesterol molecules, we observe raftlike structures and determine the ordering of the cholesterol molecules in binary cholesterol-containing lipid membranes. From coarse-grained computer simulations, heterogenous membranes structures were observed and characterized as small, ordered domains. Neutron diffraction was used to study the lateral structure of the cholesterol molecules. We find pairs of strongly bound cholesterol molecules in the liquid-disordered phase, in accordance with the umbrella model. Bragg peaks corresponding to ordering of the cholesterol molecules in the raftlike structures were observed and indexed by two different structures: a monoclinic structure of ordered cholesterol pairs of alternating direction in equilibrium with cholesterol plaques, i.e., triclinic cholesterol bilayers. PMID:25494092

Toppozini, Laura; Meinhardt, Sebastian; Armstrong, Clare L; Yamani, Zahra; Ku?erka, Norbert; Schmid, Friederike; Rheinstädter, Maikel C

2014-11-28

407

Alcohol's Effects on Lipid Bilayer Properties  

PubMed Central

Alcohols are known modulators of lipid bilayer properties. Their biological effects have long been attributed to their bilayer-modifying effects, but alcohols can also alter protein function through direct protein interactions. This raises the question: Do alcohol's biological actions result predominantly from direct protein-alcohol interactions or from general changes in the membrane properties? The efficacy of alcohols of various chain lengths tends to exhibit a so-called cutoff effect (i.e., increasing potency with increased chain length, which that eventually levels off). The cutoff varies depending on the assay, and numerous mechanisms have been proposed such as: limited size of the alcohol-protein interaction site, limited alcohol solubility, and a chain-length-dependent lipid bilayer-alcohol interaction. To address these issues, we determined the bilayer-modifying potency of 27 aliphatic alcohols using a gramicidin-based fluorescence assay. All of the alcohols tested (with chain lengths of 1–16 carbons) alter the bilayer properties, as sensed by a bilayer-spanning channel. The bilayer-modifying potency of the short-chain alcohols scales linearly with their bilayer partitioning; the potency tapers off at higher chain lengths, and eventually changes sign for the longest-chain alcohols, demonstrating an alcohol cutoff effect in a system that has no alcohol-binding pocket. PMID:21843475

Ingólfsson, Helgi I.; Andersen, Olaf S.

2011-01-01

408

Clinical Trial: Marine Lipid Suppositories as Laxatives  

PubMed Central

Cod-liver oil and other marine products containing polyunsaturated fatty acids have anti-inflammatory, anti-bacterial and anti-viral effects and may be useful in the treatment of various inflammatory and infectious diseases. We developed suppositories and ointment with 30% free fatty acid (FFA) extract from omega-3 fish oil. Our purpose was to evaluate the safety of marine lipid suppositories and ointment in healthy volunteers and to explore the laxative effect of the suppositories. Thirty healthy volunteers were randomized either to a study group administrating 30% FFA suppositories and applying 30% FFA ointment to the perianal region twice per day for two weeks, or to a control group using placebo suppositories and ointment in a double blinded manner. Results: No serious toxic effects or irritation were observed. In the study group 93% felt the urge to defecate after administration of the suppositories as compared to 37% in the control group (P = 0.001). Subsequently 90% in the study group defecated, compared to 33% in the control group (P = 0.001). Conclusion: The marine lipid suppositories and ointment were well tolerated with no significant toxic side effects observed during the study period. The suppositories have a distinct laxative effect and we aim to explore this effect in further clinical trials. PMID:23118720

Ormarsson, Orri Thor; Geirsson, Thormodur; Bjornsson, Einar Stefan; Jonsson, Tomas; Moller, Pall; Loftsson, Thorsteinn; Stefansson, Einar

2012-01-01

409

Lipid Biosynthesis in Developing Mustard Seed  

PubMed Central

Cotyledons of developing mustard (Sinapis alba L.) seed have been found to synthesize lipids containing the common plant fatty acids and very long-chain monounsaturated (icosenoic, erucic, and tetracosenic) and saturated (icosanoic, docosanoic, and tetracosanoic) fatty acids from various radioactive precursors. The in vivo pattern of labeling of acyl lipids, either from fatty acids synthesized `endogenously' from radioactive acetate or malonate, or from radioactive fatty acids added `exogenously', indicates the involvement of the following pathways in the biosynthesis of triacylglycerols. Palmitic, stearic, and oleic acid, synthesized in the acyl carrier protein-track, are channeled to the Coenzyme A (CoA)-track and converted to triacylglycerols via the glycerol-3-phosphate pathway. Pools of stearoyl-CoA and oleoyl-CoA are elongated to very long-chain saturated and monounsaturated acyl-CoA, respectively. Most of the very long-chain saturated acyl-CoAs acylate preformed diacylglycerols. Very long-chain monounsaturated acyl-CoAs are converted to triacylglycerols, partly via phosphatidic acids and diacylglycerols, and partly by acylation of preformed diacylglycerols. PMID:16663345

Mukherjee, Kumar D.

1983-01-01

410

Metabolic syndrome: soybean foods and serum lipids.  

PubMed Central

Metabolic syndrome is a cluster of coronary heart disease (CHD) risk factors of which central obesity, insulin resistance, increased triglycerides/decreased HDL cholesterol, and hypertension are major cardiovascular risk factors. The educational objectives of this review are to describe hypocholesteromic effects from soybean foods. Early Italian observations indicated that isolated soy protein lowered total cholesterol, especially the LDL component, in humans with elevated serum lipids. Whole soybeans, with their major phytoestrogen inflavones (genistein, daidzein, and glycetin) intact, are known to decrease both total and LDL cholesterol. Major early reviews, meta-analyses, and clinical trials in hyperlipidemic humans indicate a predictable range of decreases in serum lipids: total cholesterol (10-19%), LDL cholesterol (14-20%), and triglycerides (8-14%). Recent, large, randomized trials in postmenopausal women indicated that a soy protein component induces significant increases in HDL cholesterol. Therapy for metabolic syndrome must first be patient education, especially for predominant U.S. minority groups (Afro-, Latino-, and Native Americans). The four major preventive health educational facts necessary to reduce CHD/metabolic syndrome must now recognize that whole soybeans are abundant sources of: 1) vegetable protein, 2) high soluble fiber content, 3) virtual absence of saturated fat, though high in polyunsaturated fats, and 4) major phytoestrogens. PMID:15303407

Merritt, John C.

2004-01-01

411

The Structure of Cholesterol in Lipid Rafts  

E-print Network

Rafts, or functional domains, are transient nano- or mesoscopic structures in the plasma membrane and are thought to be essential for many cellular processes such as signal transduction, adhesion, trafficking and lipid/protein sorting. Observations of these membrane heterogeneities have proven challenging, as they are thought to be both small and short-lived. With a combination of coarse-grained molecular dynamics simulations and neutron diffraction using deuterium labeled cholesterol molecules we observe raft-like structures and determine the ordering of the cholesterol molecules in binary cholesterol-containing lipid membranes. From coarse-grained computer simulations, heterogenous membranes structures were observed and characterized as small, ordered domains. Neutron diffraction was used to study the lateral structure of the cholesterol molecules. We find pairs of strongly bound cholesterol molecules in the liquid-disordered phase, in accordance with the umbrella model. Bragg peaks corresponding to ordering of the cholesterol molecules in the raft-like structures were observed and indexed by two different structures: a monoclinic structure of ordered cholesterol pairs of alternating direction in equilibrium with cholesterol plaques, i.e., triclinic cholesterol bilayers.

Laura Toppozini; Sebastian Meinhardt; Clare L. Armstrong; Zahra Yamani; Norbert Kucerka; Friederike Schmid; Maikel C. Rheinstaedter

2014-12-16

412

Oleuropein on lipid and fatty acid composition of rat heart  

Microsoft Academic Search

Male rats of the Wistar strain were given oleuropein for 3 weeks at a dose of 25 or 50 mg\\/kg of body weight. Heart samples were analyzed for the lipid composition by the Iatroscan TLCFID technique and for the fatty acid profile of neutral and polar lipids by the capillary gas chromatography. In addition, the oleuropein, ?- and ?-tocopherol content

Valentina Ruíz-Gutiérrez; Francisco J. G. Muriana; Roberto Maestro; Enrique Graciani

1995-01-01

413

Hydrogen isotope fractionation during lipid biosynthesis by Tetrahymena thermophila  

E-print Network

Hydrogen isotope fractionation during lipid biosynthesis by Tetrahymena thermophila Sitindra S Accepted 7 September 2013 Available online 16 September 2013 a b s t r a c t Hydrogen isotope ratio values from recording the hydrogen isotope composition of ambient water, dD values of lipids also depend

414

Antioxidant Activity of Solid Lipid Nanoparticles Loaded with Umbelliferone  

Microsoft Academic Search

The objective of this investigation was to develop solid lipid nanoparticles (SLNs) of umbelliferone by means of high shear homogenization technique and to evaluate the efficiency of SLN systems in preserving and enhancing antioxidant activity of flavonoid active component. The aqueous SLN dispersions combine two structural types of lipid compounds and different types of emulsifiers including a mixture of monoalkyl

I. Lacatusu; N. Badea; A. Murariu; O. Oprea; D. Bojin; A. Meghea

2011-01-01

415

Original article Effect of dietary levels of lipid and carbohydrate  

E-print Network

Original article Effect of dietary levels of lipid and carbohydrate on growth performance, body of digestible carbohydrate and the highest plasma glucose level was attained later at 8°C in comparison to 18°C. trout / carbohydrate/lipid ratio / growth performance / glycaemia / temperature Résumé ― Effets

Paris-Sud XI, Université de

416

PARTICLE SIZE CHARACTERIZATION OF STARCH-LIPID COMPOSITES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Starch-lipid composites (SLCs) have been used as fat replacers and stabilizers in beef patties, dairy products, and baked goods and the technology has been patented under the trademark FanteskTM. The SLCs are produced by mixing aqueous starch slurry with a lipid source, and steam jet-cooking. The ...

417

Lipid requirements in the nutrition of dairy ewes  

Microsoft Academic Search

The aim of this review was to contribute to the knowledge of lipid requirements in dairy ewes, by reviewing experi- mental papers about lipid supplementation in dairy ewe feeding. The number of trials in ewe feeding is lower than that in dairy cow feeding and, leaving calcium soap of palm oil out of consideration, there is a lack of knowledge

Marcello Mele; Arianna Buccioni; Andrea Serra

2005-01-01

418

Giant Unilamelar Vesicles preparation protocol -Nanion Chips Lipid stock solution  

E-print Network

Giant Unilamelar Vesicles ­ preparation protocol - Nanion Chips Lipid stock solution: · 2.5mg)(Ammonium Salt) (Avanti)) ­ only if fluorescence microscope is used. Sucrose stock solution: · 300mM Sucrose: On the electrodes system 1.5µl drops form lipid stock solution were added at 5 different places on each electrode

Movileanu, Liviu

419

Polar Lipids of Archaebacteria in Sediments and Petroleums  

Microsoft Academic Search

Glycerol tetraethers with head-to-head isoprenoid 40-carbon chains that are typical of archaebacteria, in particular of methanogens, were identified in the polar lipids of sediments and petroleums. These structures are at least partially preserved in the subsurface beyond the stage of petroleum formation. Their identification provides further evidence that a significant part of geological organic matter derives from the lipids of

B. Chappe; P. Albrecht; W. Michaelis

1982-01-01

420

Fatty acid methyl ester profiles of bat wing surface lipids.  

PubMed

Sebocytes are specialized epithelial cells that rupture to secrete sebaceous lipids (sebum) across the mammalian integument. Sebum protects the integument from UV radiation, and maintains host microbial communities among other functions. Native glandular sebum is composed primarily of triacylglycerides (TAG) and wax esters (WE). Upon secretion (mature sebum), these lipids combine with minor cellular membrane components comprising total surface lipids. TAG and WE are further cleaved to smaller molecules through oxidation or host enzymatic digestion, resulting in a complex mixture of glycerolipids (e.g., TAG), sterols, unesterified fatty acids (FFA), WE, cholesteryl esters, and squalene comprising surface lipid. We are interested if fatty acid methyl ester (FAME) profiling of bat surface lipid could predict species specificity to the cutaneous fungal disease, white nose syndrome (WNS). We collected sebaceous secretions from 13 bat spp. using Sebutape(®) and converted them to FAME with an acid catalyzed transesterification. We found that Sebutape(®) adhesive patches removed ~6× more total lipid than Sebutape(®) indicator strips. Juvenile eastern red bats (Lasiurus borealis) had significantly higher 18:1 than adults, but 14:0, 16:1, and 20:0 were higher in adults. FAME profiles among several bat species were similar. We concluded that bat surface lipid FAME profiling does not provide a robust model predicting species susceptibility to WNS. However, these results provide baseline data that can be used for lipid roles in future ecological studies, such as life history, diet, or migration. PMID:25227993

Pannkuk, Evan L; Fuller, Nathan W; Moore, Patrick R; Gilmore, David F; Savary, Brett J; Risch, Thomas S

2014-11-01

421

Phytotoxic Activity of Quinone and Resorcinolic Lipid Derivatives  

Technology Transfer Automated Retrieval System (TEKTRAN)

Based on the phytotoxic activity of sorgoleone and resorcinolic lipids identified from the roots extracts of sorghum, 8 resorcinolic lipids derivatives and 10 quinones with varying side chains size were synthesized. The compounds were submitted to phtotoxicity assay against monocot and dicot species...

422

Charge-induced phase separation in lipid membranes  

E-print Network

The phase separation in lipid bilayers that include negatively charged lipids is examined experimentally. We observed phase-separated structures and determined the membrane miscibility temperatures in several binary and ternary lipid mixtures of unsaturated neutral lipid, dioleoylphosphatidylcholine (DOPC), saturated neutral lipid, dipalmitoylphosphatidylcholine (DPPC), unsaturated charged lipid, dioleoylphosphatidylglycerol (DOPG$^{\\scriptsize{(-)}}$), saturated charged lipid, dipalmitoylphosphatidylglycerol (DPPG$^{\\scriptsize{(-)}}$), and cholesterol. In binary mixtures of saturated and unsaturated charged lipids, the combination of the charged head with the saturation of hydrocarbon tail is a dominant factor for the stability of membrane phase separation. DPPG$^{\\scriptsize{(-)}}$ enhances phase separation, while DOPG$^{\\scriptsize{(-)}}$ suppresses it. Furthermore, the addition of DPPG$^{\\scriptsize{(-)}}$ to a binary mixture of DPPC/cholesterol induces phase separation between DPPG$^{\\scriptsize{(-)}}$-rich and cholesterol-rich phases. This indicates that cholesterol localization depends strongly on the electric charge on the hydrophilic head group rather than on the ordering of the hydrocarbon tails. Finally, when DPPG$^{\\scriptsize{(-)}}$ was added to a neutral ternary system of DOPC/DPPC/Cholesterol (a conventional model of membrane rafts), a three-phase coexistence was produced. We conclude by discussing some qualitative features of the phase behaviour in charged membranes using a free energy approach.

Hiroki Himeno; Naofumi Shimokawa; Shigeyuki Komura; David Andelman; Tsutomu Hamada; Masahiro Takagi

2014-05-19

423

Recent advances in lipid nutrition in fish larvae  

Microsoft Academic Search

Due to the importance of dietary lipid utilization for larval rearing success, increasing attention has been paid during the last years to different aspects of larval lipid nutrition such as digestion, absorption, transport and metabolism, which are frequently studied by different research groups. The present study reviews the published information on these aspects, including some recent results obtained in our

M. S. Izquierdo; J. Socorro; L. Arantzamendi; C. M. Hernández-Cruz

2000-01-01

424

Compartmentalized Intrapulmonary Pharmacokinetics of Amphotericin B and Its Lipid Formulations  

Microsoft Academic Search

We investigated the compartmentalized intrapulmonary pharmacokinetics of amphotericin B and its lipid formulations in healthy rabbits. Cohorts of three to seven noninfected, catheterized rabbits received 1 mg of amphotericin B deoxycholate (DAMB) per kg of body weight or 5 mg of either amphotericin B colloidal dispersion (ABCD), amphotericin B lipid complex (ABLC), or liposomal amphotericin B (LAMB) per kg once

Andreas H. Groll; Caron A. Lyman; Vidmantas Petraitis; Ruta Petraitiene; Derek Armstrong; Diana Mickiene; Raul M. Alfaro; Robert L. Schaufele; Tin Sein; John Bacher; Thomas J. Walsh

2006-01-01

425

Membrane Recognition and Targeting by Lipid-Binding Domains  

NSDL National Science Digital Library

With eight figures, one table, and 155 references, this STKE Review describes the structural features that explain how modular domains interact with lipids. Various specific and nonspecific interactions contribute to the ability of proteins to recognize cellular membranes, allowing proteins with lipid-binding domains to play roles in cellular signaling and membrane trafficking.

Jonathan P. DiNitto (University of Massachusetts Medical School;Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology; REV); Thomas C. Cronin (University of Massachusetts Medical School;Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology REV); David G. Lambright (University of Massachusetts Medical School;Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology REV)

2003-12-16

426

Biogenesis and functions of lipid droplets in plants  

Technology Transfer Automated Retrieval System (TEKTRAN)

The compartmentation of neutral lipids in plant tissues is mostly associated with seed tissues, where triacylglycerols (TAGs) stored within lipid droplets (LDs) serve as an essential physiological energy and carbon reserve during post-germinative growth. However, some non-seed tissues, such as leave...

427

LIPID COMPOSITION OF OVERWINTERING ALFALFA LEAFCUTTING BEE PREPUPAE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Alfalfa leafcutting bees, Megachile rotundata (F.) overwinter as prepupae. The cuticular and internal lipids were extracted from prepupae that had been held at 4 C for eight months. Cuticular lipid components were separated, identified and quantitated by capillary gas chromatography (CGC) and CGC-m...

428

Peptide lipidation stabilizes structure to enhance biological function?  

PubMed Central

Medicines that decrease body weight and restore nutrient tolerance could improve human diabetes and obesity treatment outcomes. We developed lipid–acylated glucagon analogs that are co-agonists for the glucagon and glucagon-like peptide 1 receptors, and stimulate weight loss and plasma glucose lowering in pre-diabetic obese mice. Our studies identified lipid acylation (lipidation) can increase and balance in vitro potencies of select glucagon analogs for the two aforementioned receptors in a lipidation site-dependent manner. A general capacity for lipidation to enhance the secondary structure of glucagon analogs was recognized, and the energetics of this effect quantified. The molecular structure of a lipid–acylated glucagon analog in water was also characterized. These results support that lipidation can modify biological activity through thermodynamically-favorable intramolecular interactions which stabilize structure. This establishes use of lipidation to achieve specific pharmacology and implicates similar endogenous post-translational modifications as physiological tools capable of refining biological action in means previously underappreciated. PMID:24327962

Ward, Brian P.; Ottaway, Nickki L.; Perez-Tilve, Diego; Ma, Dejian; Gelfanov, Vasily M.; Tschöp, Matthias H.; DiMarchi, Richard D.

2013-01-01

429

Enzymes inside lipid vesicles: preparation, reactivity and applications  

Microsoft Academic Search

There are a number of methods that can be used for the preparation of enzyme-containing lipid vesicles (liposomes) which are lipid dispersions that contain water-soluble enzymes in the trapped aqueous space. This has been shown by many investigations carried out with a variety of enzymes. A review of these studies is given and some of the main results are summarized.

Peter Walde; Sosaku Ichikawa

2001-01-01

430

Cobalt carbonyl complexes as probes for alkyne-tagged lipids.  

PubMed

Monitoring lipid distribution and metabolism in cells and biological fluids poses many challenges because of the many molecular species and metabolic pathways that exist. This study describes the synthesis and study of molecules that contain an alkyne functional group as surrogates for natural lipids in cultured cells. Thus, hexadec-15-ynoic and hexadec-7-ynoic acids were readily incorporated into RAW 264.7 cells, principally as phosphocholine esters; the alkyne was used as a "tag" that could be transformed to a stable dicobalt-hexacarbonyl complex; and the complex could then be detected by HPLC/MS or HPLC/UV(349nm). The 349 nm absorbance of the cobalt complexes was used to provide qualitative and quantitative information about the distribution and cellular concentrations of the alkyne lipids. The alkyne group could also be used as an affinity tag for the lipids by a catch-and-release strategy on phosphine-coated silica beads. Lipid extracts were enriched in the tagged lipids in this way, making the approach of potential utility to study lipid transformations in cell culture. Both terminal alkynes and internal alkynes were used in this affinity "pull-down" strategy. This method facilitates measuring lipid species that might otherwise fall below limits of detection. PMID:23307946

Tallman, Keri A; Armstrong, Michelle D; Milne, Stephen B; Marnett, Lawrence J; Brown, H Alex; Porter, Ned A

2013-03-01

431

Tethered Lipid Bilayers on Electrolessly Deposited Gold for Bioelectronic Applications  

E-print Network

Tethered Lipid Bilayers on Electrolessly Deposited Gold for Bioelectronic Applications Neeraj Kohli interface consisting of an electrolessly deposited gold film overlaid with a tethered bilayer lipid membrane (tBLM). Self-assembly of colloidal gold particles was used to create an electrolessly deposited gold

Lee, Ilsoon

432

The role of epidermal lipids in cutaneous permeability barrier homeostasis  

Microsoft Academic Search

The permeability barrier is required for terres- trial life and is localized to the stratum corneum, where extracellular lipid membranes inhibit water movement. The lipids that constitute the extracellular matrix have a unique composition and are 50% ceramides, 25% choles- terol, and 15% free fatty acids. Essential fatty acid de- ficiency results in abnormalities in stratum corneum structure function. The

Kenneth R. Feingold

433

Continuum Modeling of Evolving Compositional Microdomains in Lipid Membranes  

NASA Astrophysics Data System (ADS)

In this thesis, we develop and employ coarse-grained continuum models to investigate the structure and dynamics of compositional lipid microdomains in lipid bilayer membranes, both synthetic and natural. In the case of synthetic membranes, a novel diffuse-interface model is employed to study phase transition kinetics in immiscible lipid systems. The model couples the Cahn-Hilliard equation to the Stokes equation in order to assess the roles of membrane and solvent hydrodynamics on coarsening kinetics. In contrast to the conventional wisdom, simulation results demonstrate that compositional domain morphologies evolve in time in a non-self similar manner at large Peclet numbers, implying the breakdown of dynamical scaling. In the case of natural membranes, a non-equilibrium model is developed to account for the presence of vesicular and non-vesicular lipid transport to and from the membrane in living cells. Simulations and analytical arguments imply that the emerging lipid microdomain structure is controlled by these lipid "recycling" processes. Furthermore, the spatial distribution and life times of lipid microdomains are also affected by membrane proteins. In particular, such proteins can both stabilize small domains and induce the growth of larger, spatially extended ones. Finally, a comprehensive classification scheme for theoretical lipid microdomain formation scenarios is proposed, enabling the experimental verification/falsification of the scenarios based on structural and temporal correlation data. The feasibility of the method is demonstrated by developing a hybrid particle-continuum model to extract these correlations from simulated multiple particle tracking experiments.

Fan, Jun

434

Charge-induced phase separation in lipid membranes.  

PubMed

Phase separation in lipid bilayers that include negatively charged lipids is examined experimentally. We observed phase-separated structures and determined the membrane miscibility temperatures in several binary and ternary lipid mixtures of unsaturated neutral lipid, dioleoylphosphatidylcholine (DOPC), saturated neutral lipid, dipalmitoylphosphatidylcholine (DPPC), unsaturated charged lipid, dioleoylphosphatidylglycerol (DOPG((-))), saturated charged lipid, dipalmitoylphosphatidylglycerol (DPPG((-))), and cholesterol. In binary mixtures of saturated and unsaturated charged lipids, the combination of the charged head with the saturation of the hydrocarbon tail is a dominant factor in the stability of membrane phase separation. DPPG((-)) enhances phase separation, while DOPG((-)) suppresses it. Furthermore, the addition of DPPG((-)) to a binary mixture of DPPC/cholesterol induces phase separation between DPPG((-))-rich and cholesterol-rich phases. This indicates that cholesterol localization depends strongly on the electric charge on the hydrophilic head group rather than on the ordering of the hydrocarbon tails. Finally, when DPPG((-)) was added to a neutral ternary system of DOPC/DPPC/cholesterol (a conventional model of membrane rafts), a three-phase coexistence was produced. We conclude by discussing some qualitative features of the phase behaviour in charged membranes using a free energy approach. PMID:25154325

Himeno, Hiroki; Shimokawa, Naofumi; Komura, Shigeyuki; Andelman, David; Hamada, Tsutomu; Takagi, Masahiro

2014-10-28

435

Phase Behavior of Lipid Monolayers Containing DPPC and Cholesterol Analogs  

E-print Network

in animal cell membranes. Furthermore, we find unusual phase behavior for dipalmitoyl phosphatidylcholinePhase Behavior of Lipid Monolayers Containing DPPC and Cholesterol Analogs Benjamin L. Stottrup 98195 ABSTRACT We investigate the miscibility phase behavior of lipid monolayers containing a wide

Stottrup, Benjamin L.

436

NOE EFFECTS IN NATURAL UNDILUTED HIGHLY POLYUNSATURATED LIPIDS  

Technology Transfer Automated Retrieval System (TEKTRAN)

13C NMR spectra of natural, unenriched low melting point-polyunsaturated lipids (sardine oil and cod muscle glycerophosphocholine, seal oil and dolphin oil) and poultry fat were obtained. Undiluted lipid and 50 vol% CDCl3 diluted samples were run and processed under identical conditions. The high ...

437

Sorting of Lipids and Proteins in Membrane Curvature Gradients  

PubMed Central

The sorting of lipids and proteins in cellular trafficking pathways is a process of central importance in maintaining compartmentalization in eukaryotic cells. However, the mechanisms behind these sorting phenomena are currently far from being understood. Among several mechanistic suggestions, membrane curvature has been invoked as a means to segregate lipids and proteins in cellular sorting centers. To assess this hypothesis, we investigate the sorting of lipid analog dye trace components between highly curved tubular membranes and essentially flat membranes of giant unilamellar vesicles. Our experimental findings indicate that intracellular lipid sorting, contrary to frequent assumptions, is unlikely to occur by lipids fitting into membrane regions of appropriate curvature. This observation is explained in the framework of statistical mechanical lattice models that show that entropy, rather than curvature energy, dominates lipid distribution in the absence of strongly preferential lateral intermolecular interactions. Combined with previous findings of curvature induced phase segregation, we conclude that lipid cooperativity is required to enable efficient sorting. In contrast to lipid analog dyes, the peripheral membrane binding protein Cholera toxin subunit B is effectively curvature-sorted. The sorting of Cholera toxin subunit B is rationalized by statistical models. We discuss the implications of our findings for intracellular sorting mechanisms. PMID:19348750

Tian, A.; Baumgart, T.

2009-01-01

438

Jamming the endosomal system: lipid rafts and lysosomal storage diseases  

Microsoft Academic Search

Some lysosomal storage diseases result from the accumulation of lipids in degradative compartments of the endocytic pathway. Particularly striking is the example of the Niemann–Pick (NP) syndrome. NP syndromes types A and B are characterized by the accumulation of sphingomyelin, whereas cholesterol typically accumulates in NP type C. These two different lipids, sphingomyelin and cholesterol, are normal constituents of specific

Kai Simons; Jean Gruenberg

2000-01-01

439

Observations on the lipids of Oochoristica agamae (Cestoda).  

PubMed

An investigation of the lipids of Oochoristica agamae, an anoplocephalid cestode of the Agama lizard, was undertaken. Total lipids of the parasite accounted for 8.4% of the fresh weight; neutral lipids comprised 82.98% of the total, glycolipids, 5.01%, and phospholipids, 12.03%. The major lipid classes in O. agamae include triglycerides, cholesterol, phosphatidyl choline, and phosphatidyl ethanolamine. The 16- and 18-carbon fatty acids were predominant in the parasite. Hexadecenoic acid, usually found at low concentrations in the lipids of helminth parasites, was the most abundant of the 16-carbon fatty acids of O. agamae (notably in the neutral lipid fraction). Although octadecatrienoic acid occurred only in trace amounts in the intestinal contents of the host, significant amounts of this fatty acid were detected in the parasite. A lack of 20-carbon fatty acids was determined in the lipids of the host's intestinal contents and the neutral lipid fraction of the parasite. O. agamae is suspected to be capable of modifying fatty acids obtained from dietary sources by chain elongation. PMID:2704724

Aisien, S O; Ogiji, E E

1989-01-01

440

Production of lipid compounds in the yeast Saccharomyces cerevisiae  

Microsoft Academic Search

This review describes progress using the yeast Saccharomyces cerevisiae as a model organism for the fast and efficient analysis of genes and enzyme activities involved in the lipid biosynthetic pathways of several donor organisms. Furthermore, we assess the impact of baker's yeast on the production of novel, high-value lipid compounds. Yeast can be genetically modified to produce selected substances in

M. Veen; C. Lang

2004-01-01

441

Lipid regulation of cell membrane structure and function  

Microsoft Academic Search

Recent studies of structure-function relationships in biological membranes have revealed fundamental con- cepts concerning the regulation of cellular membrane function by membrane lipids. Considerable progress has been made in understanding the roles played by two membrane lipids: cholesterol and phosphatidyl- ethanolamine. Cholesterol has been shown to regulate ion pumps, which in some cases show an absolute de- pendence on cholesterol

PHILIP L. YEAGLE

442

The Central Clock Neurons Regulate Lipid Storage in Drosophila  

Microsoft Academic Search

A proper balance of lipid breakdown and synthesis is essential for achieving energy homeostasis as alterations in either of these processes can lead to pathological states such as obesity. The regulation of lipid metabolism is quite complex with multiple signals integrated to control overall triglyceride levels in metabolic tissues. Based upon studies demonstrating effects of the circadian clock on metabolism,

Justin R. DiAngelo; Renske Erion; Amanda Crocker; Amita Sehgal

2011-01-01

443

Lysosome/lipid droplet interplay in metabolic diseases.  

PubMed

Lysosomes and lipid droplets are generally considered as intracellular compartments with divergent roles in cell metabolism, lipid droplets serving as lipid reservoirs in anabolic pathways, whereas lysosomes are specialized in the catabolism of intracellular components. During the last few years, new insights in the biology of lysosomes has challenged this view by providing evidence for the importance of lysosome recycling as a sparing mechanism to maintain cellular fitness. On the other hand the understanding of lipid droplets has evolved from an inert intracellular deposit toward the status of an intracellular organelle with dynamic roles in cellular homeostasis beyond storage. These unrelated aspects have also recently converged in the finding of unexpected