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Sample records for algal cell density

  1. Regulation of the pigment optical density of an algal cell: filling the gap between photosynthetic productivity in the laboratory and in mass culture.

    PubMed

    Formighieri, Cinzia; Franck, Fabrice; Bassi, Roberto

    2012-11-30

    An increasing number of investors is looking at algae as a viable source of biofuels, beside cultivation for human/animal feeding or to extract high-value chemicals and pharmaceuticals. However, present biomass productivities are far below theoretical estimations implying that a large part of the available photosynthetically active radiation is not used in photosynthesis. Light utilisation inefficiency and rapid light attenuation within a mass culture due to high pigment optical density of wild type strains have been proposed as major limiting factors reducing solar-to-biomass conversion efficiency. Analysis of growth yields of mutants with reduced light-harvesting antennae and/or reduced overall pigment concentration per cell, generated by either mutagenesis or genetic engineering, could help understanding limiting factors for biomass accumulation in photobioreactor. Meanwhile, studies on photo-acclimation can provide additional information on the average status of algal cells in a photobioreactor to be used in modelling-based predictions. Identifying limiting factors in solar-to-biomass conversion efficiency is the first step for planning strategies of genetic improvement and domestication of algae to finally fill the gap between theoretical and industrial photosynthetic productivity.

  2. Energy evaluation of algal cell disruption by high pressure homogenisation.

    PubMed

    Yap, Benjamin H J; Dumsday, Geoff J; Scales, Peter J; Martin, Gregory J O

    2015-05-01

    The energy consumption of high pressure homogenisation (HPH) was analysed to determine the feasibility of rupturing algal cells for biodiesel production. Experimentally, the processing capacity (i.e. flow rate), power draw and cell disruption efficiency of HPH were independent of feed concentration (for Nannochloropsis sp. up to 25%w/w solids). Depending on the homogenisation pressure (60-150 MPa), the solids concentration (0.25-25%w/w), and triacylglyceride (TAG) content of the harvested algal biomass (10-30%), the energy consumed by HPH represented between 6% and 110-times the energy density of the resulting biodiesel. Provided the right species (weak cell wall and high TAG content) is selected and the biomass is processed at a sufficiently high solids concentration, HPH can consume a small fraction of the energy content of the biodiesel produced. This study demonstrates the feasibility of process-scale algal cell disruption by HPH based on its energy requirement.

  3. The influence of algal densities on the toxicity of chromium for Ceriodaphnia dubia Richard (Cladocera, Crustacea).

    PubMed

    Rodgher, S; Espíndola, E L G

    2008-05-01

    Food availability may affect metal toxicity for aquatic organisms. In the present study, the influence of high, medium and low densities of the algae Pseudokirchneriella subcapitata (10(6), 10(5) and 10(4) cells.mL(-1), respectively) on the chronic toxicity of chromium to the cladoceran Ceriodaphnia dubia was investigated. C. dubia was exposed to a range of chromium concentration from 2.71 to 34.04 microg.L(-1) and fed with algae at various densities. In another experiment, the green alga was exposed to chromium concentrations (94 to 774 microg.L(-1)) and supplied as food in different densities to zooplankton. The survival and reproduction of the cladoceran were measured in these toxicity tests. The IC50 for Cr to P. subcapitata and metal accumulated by algal cells were determined. The results of a bifactorial analysis (metal versus algal densities) showed that metal toxicity to zooplankton was dependent on algal densities. Significant toxic effects on the reproduction and survival of C. dubia were observed at 8.73, 18.22 and 34.04 microg.L(-1) Cr when the test organisms were fed with 10(6) cells.mL(-1) of P. subcapitata. Although the chlorophyta retain low chromium content, a decrease in the reproduction and survival of C. dubia occurred when they were fed with high algal density contaminated with 774 microg.L(-1) Cr. It was concluded that high algal density have an appreciable influence on chromium toxicity to daphnids.

  4. Centriole asymmetry determines algal cell geometry

    PubMed Central

    Marshall, Wallace F.

    2012-01-01

    The mechanisms that determine the shape and organization of cells remain largely unknown. Green algae such as Chlamydomonas provide excellent model systems for studying cell geometry due to their highly reproducible cell organization. Structural and genetic studies suggest that asymmetry of the centriole (basal body) plays a critical determining role in organizing the internal organization of algal cells, through the attachment of microtubule rootlets and other large fiber systems to specific sets of microtubule triplets on the centriole. Thus to understand cell organization, it will be critical to understand how the different triplets of the centriole come to have distinct molecular identities. PMID:23026116

  5. The effect of light direction and suspended cell concentrations on algal biofilm growth rates.

    PubMed

    Schnurr, Peter J; Espie, George S; Allen, D Grant

    2014-10-01

    Algae biofilms were grown in a semicontinuous flat plate biofilm photobioreactor to study the effects of light direction and suspended algal cell populations on algal biofilm growth. It was determined that, under the growth conditions and biofilm thicknesses studied, light direction had no effect on long-term algal biofilm growth (26 days); however, light direction did affect the concentration of suspended algal cells by influencing the photon flux density in the growth medium in the photobioreactors. This suspended algal cell population affected short-term (7 days) algae cell recruitment and algal biofilm growth, but additional studies showed that enhanced suspended algal cell populations did not affect biofilm growth rates over the long term (26 days). Studying profiles of light transmittance through biofilms as they grew showed that most of the light became attenuated by the biomass after just a few days of growth (88 % after 3 days). The estimated biofilm thicknesses after these few days of growth were approximately 150 μm. The light attenuation data suggests that, although the biofilms grew to 700-900 μm, under these light intensities, only the first few hundred micrometers of the biofilm is receiving enough light to be photosynthetically active. We postulate that this photosynthetically active layer of the biofilm grows adjacent to the light source, while the rest of the biofilm is in a stationary growth phase. The results of this study have implications for algal biofilm photobioreactor design and operation.

  6. Air pollutant production by algal cell cultures

    NASA Technical Reports Server (NTRS)

    Fong, F.; Funkhouser, E. A.

    1982-01-01

    The production of phytotoxic air pollutants by cultures of Chlorella vulgaris and Euglena gracilis is considered. Algal and plant culture systems, a fumigation system, and ethylene, ethane, cyanide, and nitrogen oxides assays are discussed. Bean, tobacco, mustard green, cantaloupe and wheat plants all showed injury when fumigated with algal gases for 4 hours. Only coleus plants showed any resistance to the gases. It is found that a closed or recycled air effluent system does not produce plant injury from algal air pollutants.

  7. Algal Cell Factories: Approaches, Applications, and Potentials

    PubMed Central

    Fu, Weiqi; Chaiboonchoe, Amphun; Khraiwesh, Basel; Nelson, David R.; Al-Khairy, Dina; Mystikou, Alexandra; Alzahmi, Amnah; Salehi-Ashtiani, Kourosh

    2016-01-01

    With the advent of modern biotechnology, microorganisms from diverse lineages have been used to produce bio-based feedstocks and bioactive compounds. Many of these compounds are currently commodities of interest, in a variety of markets and their utility warrants investigation into improving their production through strain development. In this review, we address the issue of strain improvement in a group of organisms with strong potential to be productive “cell factories”: the photosynthetic microalgae. Microalgae are a diverse group of phytoplankton, involving polyphyletic lineage such as green algae and diatoms that are commonly used in the industry. The photosynthetic microalgae have been under intense investigation recently for their ability to produce commercial compounds using only light, CO2, and basic nutrients. However, their strain improvement is still a relatively recent area of work that is under development. Importantly, it is only through appropriate engineering methods that we may see the full biotechnological potential of microalgae come to fruition. Thus, in this review, we address past and present endeavors towards the aim of creating productive algal cell factories and describe possible advantageous future directions for the field. PMID:27983586

  8. Algal Cell Factories: Approaches, Applications, and Potentials.

    PubMed

    Fu, Weiqi; Chaiboonchoe, Amphun; Khraiwesh, Basel; Nelson, David R; Al-Khairy, Dina; Mystikou, Alexandra; Alzahmi, Amnah; Salehi-Ashtiani, Kourosh

    2016-12-13

    With the advent of modern biotechnology, microorganisms from diverse lineages have been used to produce bio-based feedstocks and bioactive compounds. Many of these compounds are currently commodities of interest, in a variety of markets and their utility warrants investigation into improving their production through strain development. In this review, we address the issue of strain improvement in a group of organisms with strong potential to be productive "cell factories": the photosynthetic microalgae. Microalgae are a diverse group of phytoplankton, involving polyphyletic lineage such as green algae and diatoms that are commonly used in the industry. The photosynthetic microalgae have been under intense investigation recently for their ability to produce commercial compounds using only light, CO₂, and basic nutrients. However, their strain improvement is still a relatively recent area of work that is under development. Importantly, it is only through appropriate engineering methods that we may see the full biotechnological potential of microalgae come to fruition. Thus, in this review, we address past and present endeavors towards the aim of creating productive algal cell factories and describe possible advantageous future directions for the field.

  9. Algal Cell Response to Pulsed Waved Stimulation and Its Application to Increase Algal Lipid Production

    PubMed Central

    Savchenko, Oleksandra; Xing, Jida; Yang, Xiaoyan; Gu, Quanrong; Shaheen, Mohamed; Huang, Min; Yu, Xiaojian; Burrell, Robert; Patra, Prabir; Chen, Jie

    2017-01-01

    Generating renewable energy while sequestering CO2 using algae has recently attracted significant research attention, mostly directing towards biological methods such as systems biology, genetic engineering and bio-refining for optimizing algae strains. Other approaches focus on chemical screening to adjust culture conditions or culture media. We report for the first time the physiological changes of algal cells in response to a novel form of mechanical stimulation, or a pulsed wave at the frequency of 1.5 MHz and the duty cycle of 20%. We studied how the pulsed wave can further increase algal lipid production on top of existing biological and chemical methods. Two commonly used algal strains, fresh-water Chlorella vulgaris and seawater Tetraselmis chuii, were selected. We have performed the tests in shake flasks and 1 L spinner-flask bioreactors. Conventional Gravimetric measurements show that up to 20% increase for algal lipid could be achieved after 8 days of stimulation. The total electricity cost needed for the stimulations in a one-liter bioreactor is only one-tenth of a US penny. Gas liquid chromatography shows that the fatty acid composition remains unchanged after pulsed-wave stimulation. Scanning electron microscope results also suggest that pulsed wave stimulation induces shear stress and thus increases algal lipid production. PMID:28186124

  10. Algal Cell Response to Pulsed Waved Stimulation and Its Application to Increase Algal Lipid Production

    NASA Astrophysics Data System (ADS)

    Savchenko, Oleksandra; Xing, Jida; Yang, Xiaoyan; Gu, Quanrong; Shaheen, Mohamed; Huang, Min; Yu, Xiaojian; Burrell, Robert; Patra, Prabir; Chen, Jie

    2017-02-01

    Generating renewable energy while sequestering CO2 using algae has recently attracted significant research attention, mostly directing towards biological methods such as systems biology, genetic engineering and bio-refining for optimizing algae strains. Other approaches focus on chemical screening to adjust culture conditions or culture media. We report for the first time the physiological changes of algal cells in response to a novel form of mechanical stimulation, or a pulsed wave at the frequency of 1.5 MHz and the duty cycle of 20%. We studied how the pulsed wave can further increase algal lipid production on top of existing biological and chemical methods. Two commonly used algal strains, fresh-water Chlorella vulgaris and seawater Tetraselmis chuii, were selected. We have performed the tests in shake flasks and 1 L spinner-flask bioreactors. Conventional Gravimetric measurements show that up to 20% increase for algal lipid could be achieved after 8 days of stimulation. The total electricity cost needed for the stimulations in a one-liter bioreactor is only one-tenth of a US penny. Gas liquid chromatography shows that the fatty acid composition remains unchanged after pulsed-wave stimulation. Scanning electron microscope results also suggest that pulsed wave stimulation induces shear stress and thus increases algal lipid production.

  11. Algal Cell Response to Pulsed Waved Stimulation and Its Application to Increase Algal Lipid Production.

    PubMed

    Savchenko, Oleksandra; Xing, Jida; Yang, Xiaoyan; Gu, Quanrong; Shaheen, Mohamed; Huang, Min; Yu, Xiaojian; Burrell, Robert; Patra, Prabir; Chen, Jie

    2017-02-10

    Generating renewable energy while sequestering CO2 using algae has recently attracted significant research attention, mostly directing towards biological methods such as systems biology, genetic engineering and bio-refining for optimizing algae strains. Other approaches focus on chemical screening to adjust culture conditions or culture media. We report for the first time the physiological changes of algal cells in response to a novel form of mechanical stimulation, or a pulsed wave at the frequency of 1.5 MHz and the duty cycle of 20%. We studied how the pulsed wave can further increase algal lipid production on top of existing biological and chemical methods. Two commonly used algal strains, fresh-water Chlorella vulgaris and seawater Tetraselmis chuii, were selected. We have performed the tests in shake flasks and 1 L spinner-flask bioreactors. Conventional Gravimetric measurements show that up to 20% increase for algal lipid could be achieved after 8 days of stimulation. The total electricity cost needed for the stimulations in a one-liter bioreactor is only one-tenth of a US penny. Gas liquid chromatography shows that the fatty acid composition remains unchanged after pulsed-wave stimulation. Scanning electron microscope results also suggest that pulsed wave stimulation induces shear stress and thus increases algal lipid production.

  12. Algal cell disruption using microbubbles to localize ultrasonic energy.

    PubMed

    Krehbiel, Joel D; Schideman, Lance C; King, Daniel A; Freund, Jonathan B

    2014-12-01

    Microbubbles were added to an algal solution with the goal of improving cell disruption efficiency and the net energy balance for algal biofuel production. Experimental results showed that disruption increases with increasing peak rarefaction ultrasound pressure over the range studied: 1.90 to 3.07 MPa. Additionally, ultrasound cell disruption increased by up to 58% by adding microbubbles, with peak disruption occurring in the range of 10(8)microbubbles/ml. The localization of energy in space and time provided by the bubbles improve efficiency: energy requirements for such a process were estimated to be one-fourth of the available heat of combustion of algal biomass and one-fifth of currently used cell disruption methods. This increase in energy efficiency could make microbubble enhanced ultrasound viable for bioenergy applications and is expected to integrate well with current cell harvesting methods based upon dissolved air flotation.

  13. Low densities of sea urchins influence the structure of algal assemblages in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Palacín, Cruz; Giribet, Gonzalo; Carner, Susanna; Dantart, Luis; Turon, Xavier

    1998-06-01

    Numerous studies of interactions between urchins and algae in temperate areas have shown an important structuring effect of sea urchin populations. These studies focused almost wholly on the effect of high urchin densities on laminarian forests. In contrast, algal communities below 5-6 m depth in the northwestern Mediterranean are characterised by low sea urchin densities (<5 ind m -2) and the absence of laminarian forests. No previous research has addressed sea urchin/algal interactions in this type of community. To determine the effect of the most abundant echinoid species, Paracentrotus lividus, on well-established algal communities in this area, we performed a removal-reintroduction experiment in rocky patches located between 13 and 16 m depth in the northwestern Mediterranean, where sea urchin densities ranged between 0.9 and 3.4 ind m -2. After 6 months, the cover of non-crustose algae was significantly higher in the plots from which sea urchins had been removed than in control plots (84 vs 67% cover). These removal plots reverted to their original state upon reintroduction of sea urchins. The non-crustose algae consisted of turfing and frondose forms, with the former representing some 70% of the non-crustose algal cover. Change in the cover of turfing algae was responsible for the significant increase in algal development in the sea urchin removal plots. The response of frondose algae to the treatment varied between algal species. It is concluded that grazing by P. lividus exerts a significant effect on habitat structure, even in communities with low sea urchin densities, such as those found in vast areas of the Mediterranean sublittoral.

  14. High-density photoautotrophic algal cultures: design, construction, and operation of a novel photobioreactor system.

    PubMed

    Javanmardian, M; Palsson, B O

    1991-12-05

    A photobioreactor system has been designed, constructed and implemented to achieve high photosynthetic rates in high-density photoautotrophic algal cell suspensions. This unit is designed for efficient oxygen and biomass production rates, and it also can be used for the production of secreted products. A fiber-optic based optical transmission system that is coupled to an internal light distribution system illuminates the culture volume uniformly, at light intensities of 1.7 mW/cm(2) over a specific surface area of 3.2 cm(2)/cm(3). Uniform light distribution is achieved throughout the reactor without interfering with the flow pattern required to keep the cells in suspension. An on-line ultrafiltration unit exchanges spent with fresh medium, and its use results in very high cell densities, up to 10(9) cells/mL [3% (w/v)] for eukaryotic green alga chlorella vulgaris. DNA histograms obtained form flow cytometric analysis reveal that on-line ultrafiltration influences the growth pattern. Prior to ultrafiltration the cells seem to have at a particular point in the cell cycle where they contain multiple chromosomal equivalents. Following ultrafiltration, these cells divide, and the new cells are committed to division so that cell growth resumes. The Prototype photobioreactor system was operated both in batch and in continuous mode for over 2 months. The measured oxygen production rate of 4-6 mmol/L culture h under continuous operation is consistent with the predicted performance of the unit for the provided light intensity.

  15. [Effects of water temperature and edible algal density on the population dynamics and sexual reproduction of Moina irrasa].

    PubMed

    Li, Yu-Ying; Deng, Dao-Gui; Lei, Juan; Xi, Yi-Long

    2011-12-01

    This paper studied the population dynamics and sexual reproduction of Moina irrasa at different water temperature and edible algal density. The population density of M. irrasa was obviously higher at high than at medium and low densities of edible algae, with the maximum at high edible algal density and 20 degrees C. At the same temperatures, the average number of the offsprings first produced by per female M. irrasa declined with decreasing edible algal density, and the maximum value appeared at 25 degrees C and at high edible algal density. The male offsprings produced were obviously higher at high than at medium and low edible algal densities. There was a significant correlation between the male density and the population density of M. irrasa. The number of ephippia produced by M. irrasa declined with decreasing edible algal density, and was higher at 25 degrees C than at other temperatures. Edible algal density had larger effects on the population dynamics and sexual reproduction of M. irrasa, as compared with temperature.

  16. Yield of trihalomethanes and haloacetic acids upon chlorinating algal cells, and its prediction via algal cellular biochemical composition.

    PubMed

    Hong, Hua Chang; Mazumder, Asit; Wong, Ming Hung; Liang, Yan

    2008-12-01

    The major objective of the present study was to investigate the contribution of major biomolecules, including protein, carbohydrates and lipids, in predicting DBPs formation upon chlorination of algal cells. Three model compounds, including bovine serum albumin (BSA), starch and fish oil, as surrogates of algal-derived proteins, carbohydrates and lipids, and cells of three algae species, representing blue-green algae, green algae, and diatoms, were chlorinated in the laboratory. The results showed that BSA (27 microg mg(-1) C) and fish oil (50 microg mg(-1) C) produced more than nine times higher levels of chloroform than starch (3 microg mg(-1) C). For the formation of HAAs, BSA was shown to have higher reactivity (49 microg mg(-1) C) than fish oil and starch (5 microg mg(-1) C). For the algal cells, Nitzschia sp. (diatom) showed higher chloroform yields (48 microg mg(-1) C) but lower HAA yields (43 microg mg(-1) C) than Chlamydomonas sp. (green algae) (chloroform: 34 microg mg(-1) C; HAA: 62 microg mg(-1) C) and Oscillatoria sp. (blue-green algae) (chloroform: 26 microg mg(-1) C; HAA: 72 microg mg(-1) C). The calculated chloroform formation of cells from the three algal groups, based on their biochemical compositions, was generally consistent with the experimental data, while the predicted values for HAAs were significantly lower than the observed ones. As compared to humic substances, such as humic and fulvic acids, the algal cells appeared to be important precursors of dichloroacetic acid.

  17. Effects of DDT and dicofol on population growth of Brachionus calyciflorus under different algal (Scenedesmus obliquus) densities.

    PubMed

    Xu, Xiao-Ping; Xi, Yi-Long; Chu, Zhao-Xia; Xiang, Xian-Ling

    2014-09-01

    A number of organochlorine pesticides, including DDT and dicofol, used to be important in crop protection and management. Their residues may reach water bodies and eventually affect the non-target organisms such as rotifers. In the present study, we evaluated the effects of DDT (0.05, 0.1, 0.2 and 0.4 mg l(-1)) and dicofol (0.1, 0.2, 0.4 and 0.8 mg l(-1)) on the population growth of rotifer Brachionus calyciflorus under two levels of Scenedesmus obliquus (1.0 x 10(6) and 3.0 x 10(6) cell ml(-1)). Regardless of the food level, DDT was more toxic than dicofol to B. calyciflorus. Under low food level, DDT at 0.1 and 0.2 mg l(-1) decreased the population growth rate (r), and DDT at 0.05-0.4 mg l(-1) decreased the maximum population density (K). Dicofol at 0.4 and 0.8 mg l(-1) decreased r and K, but dicofol at 0.2 mg l(-1) increased K. Under high food level, DDT at 0.05-0.2 mg l(-1) increased K, whereas DDT at 0.4 mg l(-1) as well as dicofol at 0.4 and 0.8 mg l(-1) decreased r and K. Increase in food level increased r exposed to DDT at 0.05-0.2 mg l(-1) as well as dicofol at 0.8 mg l(-1), and Kexposed to DDTat 0.05-0.2 mg l(-1) as well as dicofol at 0.1 and 0.2 mg l(-1). DDT concentration, algal density and their interaction affected r and K of B. calyciflorus. Both dicofol concentration and algal density affected r. Dicofol concentration, algal density and their interaction affected K. Both r and K were suitable endpoints for assessing the effects of DDT and dicofol on the rotifers population dynamics under two algal densities, and the latter was more sensitive.

  18. Separation of algal cells from water by column flotation

    SciTech Connect

    Liu, J.C.; Chen, Y.M.; Ju, Y.H.

    1999-08-01

    The dispersed air flotation (DiAF) process was utilized to separate algal cells (Chlorella sp.) from water. Two types of collector, cationic N-cetyl-N,N,N-trimethylammonium bromide (CTAB) and anionic sodium dodecylsulfate (SDS), were used. It was observed that 20% of cell removal was achieved in the presence of 40 mg/L of SDS, and ca. 86% of the cells were removed at 40 mg/L of CTAB. Upon the addition of 10 mg/L of chitosan, over 90% of the cells were removed when SDS (20 mg/L) was used as the collector. Air flow rate affected cell flotation slightly. Optimum pH values for cell flotation were from 4.0 to 5.0. Flotation efficiency decreased at high ionic strength. The electrostatic interaction between collector and cell surface plays a critical role in the separation processes.

  19. Immobilized algal cells used for hydrogen production

    SciTech Connect

    Hahn, John J.; Ghirardi, Maria L.; Jacoby, William A.

    2007-10-01

    This paper explores the use of the photosynthetic green alga Chlamydomonas reinhardtii bound to solid support particles to produce hydrogen in a two-step cycle. Bound cells are more easily cycled between growth mode and hydrogen production mode. The data indicate that the presence of silica particles does not inhibit the growth of the algae in the sulfur rich growth media. Filtration experiments reveal that the algae effectively bind to the silica particles, as high removal efficiencies are observed. The silica particles appear to approach saturation algae at a mass-loading ratio of about 0.035. In hydrogen production mode, the bound algae perform about as well as free-floating algae in terms of cumulative hydrogen production. A full-factorial experiment is described in which algae concentration was deemed to have a significant effect on cumulative hydrogen production.

  20. Raman spectroscopy for the characterization of algal cells

    NASA Astrophysics Data System (ADS)

    Samek, Ota; Jonáš, Alexandr; Pilát, Zdeněk; Zemánek, Pavel; Nedbal, Ladislav; Tříska, Jan; Kotas, Petr; Trtílek, Martin

    2010-12-01

    Raman spectroscopy can elucidate fundamental questions about intercellular variability and what governs it. Moreover, knowing the metabolic response on single cell level this can significantly contribute to the study and use of microalgae in systems biology and biofuel technology. Raman spectroscopy is capable to measure nutrient dynamics and metabolism in vivo, in real-time, label free making it possible to monitor/evaluate population variability. Also, degree of unsaturation of the algae oil (iodine value) can be measured using Raman spectra obtained from single microalgae. The iodine value is the determination of the amount of unsaturation contained in fatty acids (in the form of double bonds). Here we demonstrate the capacity of the spatially resolved Raman microspectroscopy to determine the effective iodine value in lipid storage bodies of individual living algal cells. We employed the characteristic peaks in the Raman scattering spectra at 1,656 cm-1 (cis C=C stretching mode) and 1,445 cm-1 (CH2 scissoring mode) as the markers defining the ratio of unsaturated-to-saturated carbon-carbon bonds of the fatty acids in the algal lipids.

  1. Coral host cells acidify symbiotic algal microenvironment to promote photosynthesis.

    PubMed

    Barott, Katie L; Venn, Alexander A; Perez, Sidney O; Tambutté, Sylvie; Tresguerres, Martin

    2015-01-13

    Symbiotic dinoflagellate algae residing inside coral tissues supply the host with the majority of their energy requirements through the translocation of photosynthetically fixed carbon. The algae, in turn, rely on the host for the supply of inorganic carbon. Carbon must be concentrated as CO2 in order for photosynthesis to proceed, and here we show that the coral host plays an active role in this process. The host-derived symbiosome membrane surrounding the algae abundantly expresses vacuolar H(+)-ATPase (VHA), which acidifies the symbiosome space down to pH ∼ 4. Inhibition of VHA results in a significant decrease in average H(+) activity in the symbiosome of up to 75% and a significant reduction in O2 production rate, a measure of photosynthetic activity. These results suggest that host VHA is part of a previously unidentified carbon concentrating mechanism for algal photosynthesis and provide mechanistic evidence that coral host cells can actively modulate the physiology of their symbionts.

  2. Coral host cells acidify symbiotic algal microenvironment to promote photosynthesis

    PubMed Central

    Barott, Katie L.; Venn, Alexander A.; Perez, Sidney O.; Tambutté, Sylvie; Tresguerres, Martin

    2015-01-01

    Symbiotic dinoflagellate algae residing inside coral tissues supply the host with the majority of their energy requirements through the translocation of photosynthetically fixed carbon. The algae, in turn, rely on the host for the supply of inorganic carbon. Carbon must be concentrated as CO2 in order for photosynthesis to proceed, and here we show that the coral host plays an active role in this process. The host-derived symbiosome membrane surrounding the algae abundantly expresses vacuolar H+-ATPase (VHA), which acidifies the symbiosome space down to pH ∼4. Inhibition of VHA results in a significant decrease in average H+ activity in the symbiosome of up to 75% and a significant reduction in O2 production rate, a measure of photosynthetic activity. These results suggest that host VHA is part of a previously unidentified carbon concentrating mechanism for algal photosynthesis and provide mechanistic evidence that coral host cells can actively modulate the physiology of their symbionts. PMID:25548188

  3. Production of biofuel using molluscan pseudofeces derived from algal cells

    DOEpatents

    Das, Keshav C.; Chinnasamy, Senthil; Shelton, James; Wilde, Susan B.; Haynie, Rebecca S.; Herrin, James A.

    2012-08-28

    Embodiments of the present disclosure provide for novel strategies to harvest algal lipids using mollusks which after feeding algae from the growth medium can convert algal lipids into their biomass or excrete lipids in their pseudofeces which makes algae harvesting energy efficient and cost effective. The bioconverter, filter-feeding mollusks and their pseudofeces can be harvested and converted to biocrude using an advanced thermochemical liquefaction technology. Methods, systems, and materials are disclosed for the harvest and isolation of algal lipids from the mollusks, molluscan feces and molluscan pseudofeces.

  4. Changes in algal community structure via density- and trait-mediated indirect interactions in a marine ecosystem.

    PubMed

    Wada, Yoko; Iwasaki, Keiji; Yusa, Yoichi

    2013-11-01

    In various terrestrial and aquatic ecosystems, predators affect resources indirectly via intermediate prey. Such indirect interactions involve reducing the density of the prey (density-mediated indirect interactions, DMIIs) or changing the behavioral, morphological, or life history traits of the prey (trait-mediated indirect interactions, TMIIs). Although the importance of TMIIs has been highlighted recently, the strengths of both DMIIs and TMIIs under natural conditions have rarely been evaluated, especially in the context of resource community structure. We studied a three-level marine food chain involving the carnivorous snail Thais clavigera, its limpet prey Siphonaria sirius, and the limpet's food sources, the algae Lithoderma sp. and Ulva sp. We measured the strengths of DMIIs and TMIIs and observed how the algal community changes under the pressure of natural predation by T. clavigera on S. sirius. Neither DMIIs nor TMIIs affected the total algal cover or chlorophyll content per unit area. However, both types of indirect interactions caused similar changes in algal composition by increasing the cover of Ulva and decreasing the cover of Lithoderma. This change in the algal community was caused by a reduction in the limpet's preferential consumption of the competitively dominant Ulva over Lithoderma. These results suggest that both DMIIs and TMIIs have similar effects on the changes in resource community structure under natural conditions.

  5. Raman microspectroscopy of individual algal cells: sensing unsaturation of storage lipids in vivo.

    PubMed

    Samek, Ota; Jonáš, Alexandr; Pilát, Zdeněk; Zemánek, Pavel; Nedbal, Ladislav; Tříska, Jan; Kotas, Petr; Trtílek, Martin

    2010-01-01

    Algae are becoming a strategic source of fuels, food, feedstocks, and biologically active compounds. This potential has stimulated the development of innovative analytical methods focused on these microorganisms. Algal lipids are among the most promising potential products for fuels as well as for nutrition. The crucial parameter characterizing the algal lipids is the degree of unsaturation of the constituent fatty acids quantified by the iodine value. Here we demonstrate the capacity of the spatially resolved Raman microspectroscopy to determine the effective iodine value in lipid storage bodies of individual living algal cells. The Raman spectra were collected from three selected algal species immobilized in an agarose gel. Prior to immobilization, the algae were cultivated in the stationary phase inducing an overproduction of lipids. We employed the characteristic peaks in the Raman scattering spectra at 1,656 cm(-1) (cis C═C stretching mode) and 1,445 cm(-1) (CH(2) scissoring mode) as the markers defining the ratio of unsaturated-to-saturated carbon-carbon bonds of the fatty acids in the algal lipids. These spectral features were first quantified for pure fatty acids of known iodine value. The resultant calibration curve was then used to calculate the effective iodine value of storage lipids in the living algal cells from their Raman spectra. We demonstrated that the iodine value differs significantly for the three studied algal species. Our spectroscopic estimations of the iodine value were validated using GC-MS measurements and an excellent agreement was found for the Trachydiscus minutus species. A good agreement was also found with the earlier published data on Botryococcus braunii. Thus, we propose that Raman microspectroscopy can become technique of choice in the rapidly expanding field of algal biotechnology.

  6. Bacterial tracking of motile algae assisted by algal cell's vorticity field.

    PubMed

    Locsei, J T; Pedley, T J

    2009-07-01

    Previously published experimental work by other authors has shown that certain motile marine bacteria are able to track free-swimming algae by executing a zigzag path and steering toward the algae at each turn. Here, we propose that the apparent steering behaviour could be a hydrodynamic effect, whereby an algal cell's vorticity and strain-rate fields rotate a pursuing bacterial cell in the appropriate direction. Using simplified models for the bacterial and algal cells, we numerically compute the trajectory of a bacterial cell and demonstrate the plausibility of this hypothesis.

  7. Simultaneous wastewater treatment, electricity generation and biomass production by an immobilized photosynthetic algal microbial fuel cell.

    PubMed

    He, Huanhuan; Zhou, Minghua; Yang, Jie; Hu, Youshuang; Zhao, Yingying

    2014-05-01

    A photosynthetic algal microbial fuel cell (PAMFC) was constructed by the introduction of immobilized microalgae (Chlorella vulgaris) into the cathode chamber of microbial fuel cells to fulfill electricity generation, biomass production and wastewater treatment. The immobilization conditions, including the concentration of immobilized matrix, initial inoculation concentration and cross-linking time, were investigated both for the growth of C. vulgaris and power generation. It performed the best at 5 % sodium alginate and 2 % calcium chloride as immobilization matrix, initial inoculation concentration of 10(6) cell/mL and cross-linking time of 4 h. Our findings indicated that C. vulgaris immobilization was an effective and promising approach to improve the performance of PAMFC, and after optimization the power density and Coulombic efficiency improved by 258 and 88.4 %, respectively. Important parameters such as temperature and light intensity were optimized on the performance. PAMFC could achieve a COD removal efficiency of 92.1 %, and simultaneously the maximum power density reached 2,572.8 mW/m(3) and the Coulombic efficiency was 14.1 %, under the light intensity of 5,000 lux and temperature at 25 °C.

  8. Digestion of algal biomass for electricity generation in microbial fuel cells.

    PubMed

    Nishio, Koichi; Hashimoto, Kazuhito; Watanabe, Kazuya

    2013-01-01

    Algal biomass serves as a fuel for electricity generation in microbial fuel cells. This study constructed a model consortium comprised of an alga-digesting Lactobacillus and an iron-reducing Geobacter for electricity generation from photo-grown Clamydomonas cells. Total power-conversion efficiency (from Light to electricity) was estimated to be 0.47%.

  9. Sequestration of CO2 discharged from anode by algal cathode in microbial carbon capture cells (MCCs).

    PubMed

    Wang, Xin; Feng, Yujie; Liu, Jia; Lee, He; Li, Chao; Li, Nan; Ren, Nanqi

    2010-08-15

    Due to increased discharge of CO(2) is incurring problems, CO(2) sequestration technologies require substantial development. By introducing anodic off gas into an algae grown cathode (Chlorella vulgaris), new microbial carbon capture cells (MCCs) were constructed and demonstrated here to be an effective technology for CO(2) emission reduction with simultaneous voltage output without aeration (610+/-50 mV, 1000 Omega). Maximum power densities increased from 4.1 to 5.6 W/m(3) when the optical density (OD) of cathodic algae suspension increased from 0.21 to 0.85 (658 nm). Compared to a stable voltage of 706+/-21 mV (1000 Omega) obtained with cathodic dissolved oxygen (DO) of 6.6+/-1.0 mg/L in MCC, voltage outputs decreased from 654 to 189 mV over 70 h in the control reactor (no algae) accompanied with a decrease in DO from 7.6 to 0.9 mg/L, indicating that cathode electron acceptor was oxygen. Gas analysis showed that all the CO(2) generated from anode was completely eliminated by catholyte, and the soluble inorganic carbon was further converted into algal biomass. These results showed the possibility of a new method for simultaneous carbon fixing, power generation and biodiesel production during wastewater treatment without aeration.

  10. Renewable sustainable biocatalyzed electricity production in a photosynthetic algal microbial fuel cell (PAMFC).

    PubMed

    Strik, David P B T B; Terlouw, Hilde; Hamelers, Hubertus V M; Buisman, Cees J N

    2008-12-01

    Electricity production via solar energy capturing by living higher plants and microalgae in combination with microbial fuel cells are attractive because these systems promise to generate useful energy in a renewable, sustainable, and efficient manner. This study describes the proof of principle of a photosynthetic algal microbial fuel cell (PAMFC) based on naturally selected algae and electrochemically active microorganisms in an open system and without addition of instable or toxic mediators. The developed solar-powered PAMFC produced continuously over 100 days renewable biocatalyzed electricity. The sustainable performance of the PAMFC resulted in a maximum current density of 539 mA/m2 projected anode surface area and a maximum power production of 110 mW/m2 surface area photobioreactor. The energy recovery of the PAMFC can be increased by optimization of the photobioreactor, by reducing the competition from non-electrochemically active microorganisms, by increasing the electrode surface and establishment of a further-enriched biofilm. Since the objective is to produce net renewable energy with algae, future research should also focus on the development of low energy input PAMFCs. This is because current algae production systems have energy inputs similar to the energy present in the outcoming valuable products.

  11. Effects of fish density and river fertilization on algal standing stocks, invertebrates communities, and fish production in an Arctic River

    USGS Publications Warehouse

    Deegan, Linda A.; Peterson, B.J.; Golden, H.; McIvor, C.C.; Miller, M.C.

    1997-01-01

    This study examined the relative importance of bottom-up and top-down controls of an arctic stream food web by simultaneous manipulation of the top predator and nutrient availability. We created a two-step trophic system (algae to insects) by removal of the top predator (Arctic grayling, Thymallus arcticus) in fertilized and control stream reaches. Fish abundance was also increased 10 times to examine the effect of high fish density on stream ecosystem dynamics and fish. We measured the response of epilithic algae, benthic and drifting insects, and fish to nutrient enrichment and to changes in fish density. Insect grazers had little effect on algae and fish had little effect on insects. In both the control and fertilized reaches, fish growth, energy storage, and reproductive response of females declined with increased fish density. Fish growth and energy storage were more closely correlated with per capita insect availability than with per capita algal standing stock

  12. Effects of anodic oxidation of a substoichiometric titanium dioxide reactive electrochemical membrane on algal cell destabilization and lipid extraction.

    PubMed

    Hua, Likun; Guo, Lun; Thakkar, Megha; Wei, Dequan; Agbakpe, Michael; Kuang, Liyuan; Magpile, Maraha; Chaplin, Brian P; Tao, Yi; Shuai, Danmeng; Zhang, Xihui; Mitra, Somenath; Zhang, Wen

    2016-03-01

    Efficient algal harvesting, cell pretreatment and lipid extraction are the major steps challenging the algal biofuel industrialization. To develop sustainable solutions for economically viable algal biofuels, our research aims at devising innovative reactive electrochemical membrane (REM) filtration systems for simultaneous algal harvesting and pretreatment for lipid extraction. The results in this work particularly demonstrated the use of the Ti4O7-based REM in algal pretreatment and the positive impacts on lipid extraction. After REM treatment, algal cells exhibited significant disruption in morphology and photosynthetic activity due to the anodic oxidation. Cell lysis was evidenced by the changes of fluorescent patterns of dissolved organic matter (DOM) in the treated algal suspension. The lipid extraction efficiency increased from 15.2 ± 0.6 g-lipidg-algae(-1) for untreated algae to 23.4 ± 0.7 g-lipidg-algae(-1) for treated algae (p<0.05), which highlights the potential to couple algal harvesting with cell pretreatment in an integrated REM filtration process.

  13. Fueling Future with Algal Genomics

    SciTech Connect

    Grigoriev, Igor

    2012-07-05

    Algae constitute a major component of fundamental eukaryotic diversity, play profound roles in the carbon cycle, and are prominent candidates for biofuel production. The US Department of Energy Joint Genome Institute (JGI) is leading the world in algal genome sequencing (http://jgi.doe.gov/Algae) and contributes of the algal genome projects worldwide (GOLD database, 2012). The sequenced algal genomes offer catalogs of genes, networks, and pathways. The sequenced first of its kind genomes of a haptophyte E.huxleyii, chlorarachniophyte B.natans, and cryptophyte G.theta fill the gaps in the eukaryotic tree of life and carry unique genes and pathways as well as molecular fossils of secondary endosymbiosis. Natural adaptation to conditions critical for industrial production is encoded in algal genomes, for example, growth of A.anophagefferens at very high cell densities during the harmful algae blooms or a global distribution across diverse environments of E.huxleyii, able to live on sparse nutrients due to its expanded pan-genome. Communications and signaling pathways can be derived from simple symbiotic systems like lichens or complex marine algae metagenomes. Collectively these datasets derived from algal genomics contribute to building a comprehensive parts list essential for algal biofuel development.

  14. Black silicon SERS substrate: effect of surface morphology on SERS detection and application of single algal cell analysis.

    PubMed

    Deng, Yu-Luen; Juang, Yi-Je

    2014-03-15

    In this study, we have investigated the effect of the surface morphology of the black silicon substrate on surface enhanced Raman spectroscopy (SERS) and explored its application of single algal cell detection. By adjusting the O2 and SF6 flow rates in the cryogenic plasma etching process, different surface morphologies of the black silicon substrate was produced without performing the lithographic process. It was found the Raman signals were better enhanced as the tip density of the black silicon substrate increased. In addition, as the thickness of the deposited gold layer increased, the SERS effect increased as well, which could be owing to the generation of more hot spots by bridging individual silicon tips through deposition of gold layer. For the black silicon substrate with tip density of 30 tips/μm(2) and covered by 400 nm deposited gold layer, the detection limit of 10 fM R6G solution concentration with uniform SERS effect across the substrate was achieved. Furthermore, detection of individual algal cell (Chlorella vulgaris) was performed at the SERS substrate as fabricated and the Raman signals of carotenoid and lipid were substantially enhanced.

  15. Arsenic (V) induces a fluidization of algal cell and liposome membranes.

    PubMed

    Tuan, Le Quoc; Huong, Tran Thi Thanh; Hong, Pham Thi Anh; Kawakami, Tomonori; Shimanouchi, Toshinori; Umakoshi, Hiroshi; Kuboi, Ryoichi

    2008-09-01

    Arsenate is one of the most poisonous elements for living cells. When cells are exposed to arsenate, their life activities are immediately affected by various biochemical reactions, such as the binding of arsenic to membranes and the substitution of arsenic for phosphate or the choline head of phospholipids in the biological membranes. The effects of arsenate on the life activities of algae Chlorella vulgaris were investigated at various concentrations and exposure times. The results demonstrated that the living activities of algal cells (10(10)cells/L) were seriously affected by arsenate at a concentration of more than 7.5mg As/L within 24h. Algal cells and the artificial membranes (liposomes) were exposed to arsenate to evaluate its effects on the membrane fluidization. In the presence of arsenate, the membranes were fluidized due to the binding and substitution of arsenate groups for phosphates or the choline head on the their membrane surface. This fluidization of the biological membranes was considered to enhance the transport of toxicants across the membrane of algal cells.

  16. [Effects of allelochemical EMA isolated from Phragmites communis on algal cell membrane lipid and ultrastructure].

    PubMed

    Li, Feng-min; Hu, Hong-ying; Chong, Yun-xiao; Men, Yu-jie; Guo, Mei-ting

    2007-07-01

    In order to reveal the antialgal mechanisms of allelochemicals, effects of the allelochemical eathyl-2-methyl acetoacetate (EMA) on cell membrane lipid and ultrastructure of Chlorella pyrenoidosa, Microcystis aeruginosa and Chlorella vulagaris were studied in this paper. The lipid fatty acids of the algal membrane were isolated following the Bligh and Dye method and quantified by gas chromatograph/mass spectrometry. The ultrastructure of algal cells was observed with TEM. The results showed that EMA increased the contents of linolenic acid and linolic acid with increment of 14%, while decreased the content of myristic acid and cetylic acid in C. pyrenoidosa, membrane. The content of unsaturated fatty acids C18:1 and C18:2 increased 12% and 10% in M. aeruginosa with the addition of EMA, while the content of saturated fatty acids C18:0 and C16:0 decreased. EMA showed no significant change in the fatty acid composition in C. vulagaris under the experiment condition. EMA broke off cell wall of C. pyrenoidosa and M. aeruginosa. EMA damaged the cell membrane and the inclusion of algal cell leaked out. Nuclear and mitochondrial structure was damaged with the addition of EMA. EMA showed no significant change in the ultrastructure of C. vulgaris.

  17. Biogenic gradients in algal density affect the emergent properties of spatially self-organized mussel beds.

    PubMed

    Liu, Quan-Xing; Weerman, Ellen J; Gupta, Rohit; Herman, Peter M J; Olff, Han; van de Koppel, Johan

    2014-07-06

    Theoretical models highlight that spatially self-organized patterns can have important emergent effects on the functioning of ecosystems, for instance by increasing productivity and affecting the vulnerability to catastrophic shifts. However, most theoretical studies presume idealized homogeneous conditions, which are rarely met in real ecosystems. Using self-organized mussel beds as a case study, we reveal that spatial heterogeneity, resulting from the large-scale effects of mussel beds on their environment, significantly alters the emergent properties predicted by idealized self-organization models that assume homogeneous conditions. The proposed model explicitly considers that the suspended algae, the prime food for the mussels, are supplied by water flow from the seaward boundary of the bed, which causes in combination with consumption a gradual depletion of algae over the simulated domain. Predictions of the model are consistent with properties of natural mussel patterns observed in the field, featuring a decline in mussel biomass and a change in patterning. Model analyses reveal a fundamental change in ecosystem functioning when this self-induced algal depletion gradient is included in the model. First, no enhancement of secondary productivity of the mussels comparing with non-patterns states is predicted, irrespective of parameter setting; the equilibrium amount of mussels is entirely set by the input of algae. Second, alternate stable states, potentially present in the original (no algal gradient) model, are absent when gradual depletion of algae in the overflowing water layer is allowed. Our findings stress the importance of including sufficiently realistic environmental conditions when assessing the emergent properties of self-organized ecosystems.

  18. Production of algal biomass (Chlorella vulgaris) using sediment microbial fuel cells.

    PubMed

    Jeon, Hyeon Jin; Seo, Kyu-won; Lee, Sang Hyun; Yang, Yung-Hun; Kumaran, Rangarajulu Senthil; Kim, Sunghyun; Hong, Seok Won; Choi, Yong Su; Kim, Hyung Joo

    2012-04-01

    In this study, a novel algal biomass production method using a sediment microbial fuel cell (SMFC) system was assessed. Under the experimental conditions, CO(2) generation from the SMFC and its rate of increase were found to be dependent on the current generated from the SMFC. However, the CH(4) production rate from the SMFC was inhibited by the generation of current. When Chlorella vulgaris was inoculated into the cathode compartment of the SMFC and current was generated under 10 Ω resistance, biomass production from the anode compartment was observed to be closely associated with the rate of current generation from the SMFC. The experimental results demonstrate that 420 mg/L of algae (dry cell weight) was produced when the current from the SMFC reached 48.5 mA/m(2). Therefore, SMFC could provide a means for producing algal biomass via CO(2) generated by the oxidation of organics upon current generation.

  19. Marine algal fucoxanthin inhibits the metastatic potential of cancer cells.

    PubMed

    Chung, Tae-Wook; Choi, Hee-Jung; Lee, Ji-Yeon; Jeong, Han-Sol; Kim, Cheorl-Ho; Joo, Myungsoo; Choi, Jun-Yong; Han, Chang-Woo; Kim, So-Yeon; Choi, Jae-Sue; Ha, Ki-Tae

    2013-10-04

    Metastasis is major cause of malignant cancer-associated mortality. Fucoxanthin has effect on various pharmacological activities including anti-cancer activity. However, the inhibitory effect of fucoxanthin on cancer metastasis remains unclear. Here, we show that fucoxanthin isolated from brown alga Saccharina japonica has anti-metastatic activity. To check anti-metastatic properties of fucoxanthin, in vitro models including assays for invasion, migration, actin fiber organization and cancer cell-endothelial cell interaction were used. Fucoxanthin inhibited the expression and secretion of MMP-9 which plays a critical role in tumor invasion and migration, and also suppressed invasion of highly metastatic B16-F10 melanoma cells as evidenced by transwell invasion assay. In addition, fucoxanthin diminished the expressions of the cell surface glycoprotein CD44 and CXC chemokine receptor-4 (CXCR4) which play roles in migration, invasion and cancer-endothelial cell adhesion. Fucoxanthin markedly suppressed cell migration in wound healing assay and inhibited actin fiber formation. The adhesion of B16-F10 melanoma cells to the endothelial cells was significantly inhibited by fucoxanthin. Moreover, in experimental lung metastasis in vivo assay, fucoxanthin resulted in significant reduction of tumor nodules. Taken together, we demonstrate, for the first time, that fucoxanthin suppresses metastasis of highly metastatic B16-F10 melanoma cells in vitro and in vivo.

  20. A new approach for the estimation of phytoplankton cell counts associated with algal blooms.

    PubMed

    Nazeer, Majid; Wong, Man Sing; Nichol, Janet Elizabeth

    2017-07-15

    This study proposes a method for estimating phytoplankton cell counts associated with an algal bloom, using satellite images coincident with in situ and meteorological parameters. Satellite images from Landsat Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), Operational Land Imager (OLI) and HJ-1 A/B Charge Couple Device (CCD) sensors were integrated with the meteorological observations to provide an estimate of phytoplankton cell counts. All images were atmospherically corrected using the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) atmospheric correction method with a possible error of 1.2%, 2.6%, 1.4% and 2.3% for blue (450-520nm), green (520-600nm), red (630-690nm) and near infrared (NIR 760-900nm) wavelengths, respectively. Results showed that the developed Artificial Neural Network (ANN) model yields a correlation coefficient (R) of 0.95 with the in situ validation data with Sum of Squared Error (SSE) of 0.34cell/ml, Mean Relative Error (MRE) of 0.154cells/ml and a bias of -504.87. The integration of the meteorological parameters with remote sensing observations provided a promising estimation of the algal scum as compared to previous studies. The applicability of the ANN model was tested over Hong Kong as well as over Lake Kasumigaura, Japan and Lake Okeechobee, Florida USA, where algal blooms were also reported. Further, a 40-year (1975-2014) red tide occurrence map was developed and revealed that the eastern and southern waters of Hong Kong are more vulnerable to red tides. Over the 40 years, 66% of red tide incidents were associated with the Dinoflagellates group, while the remainder were associated with the Diatom group (14%) and several other minor groups (20%). The developed technology can be applied to other similar environments in an efficient and cost-saving manner.

  1. Image-based monitoring system for green algal Haematococcus pluvialis (Chlorophyceae) cells during culture.

    PubMed

    Ohnuki, Shinsuke; Nogami, Satoru; Ota, Shuhei; Watanabe, Koichi; Kawano, Shigeyuki; Ohya, Yoshikazu

    2013-11-01

    The green microalga Haematococcus pluvialis accumulates the red pigment astaxanthin accompanied by morphological changes under stress conditions, including nutrient depletion, continuous light and high temperature. To investigate the physiological state of the algal cells, we developed the digital image-processing software called HaematoCalMorph. The software automatically outputs 25 single-cell measurements of cell morphology and pigments based on color, bright-field microscopic images. Compared with manual inspection, the output values of cell shape were reliable and reproducible. The estimated pigment content fits the values calculated by conventional methods. Using a random forests classifier, we were able to distinguish flagellated cells from immotile cells and detect their transient appearance in culture. By performing principal components analysis, we also successfully monitored time-dependent morphological and colorimetric changes in culture. Thus, combined with multivariate statistical techniques, the software proves useful for studying cellular responses to various conditions as well as for monitoring population dynamics in culture.

  2. Context-dependent landscape of fear: algal density elicits risky herbivory in a coral reef.

    PubMed

    Gil, Michael A; Zill, Julie; Ponciano, José M

    2017-02-01

    Foraging theory posits that isolation from refuge habitat within a landscape increases perceived predation risk and, thus, suppresses the foraging behavior of prey species. However, these effects may depend fundamentally on resource availability, which could affect prey boldness and can change considerably through bottom-up processes. We conducted a field survey and experiment in a coral reef to test the effects of isolation from refuge habitat (i.e., reef structure) on herbivory by reef fishes and whether these effects depend on resource density. By fitting continuous-time, pure death Markov processes to our data, we found that at both the local and landscape scale distance from refuge habitat reduced herbivory in attractive resource patches of palatable benthic algae. However, our field experiment revealed that higher initial resource densities weakened negative effects of distance from refuge habitat on herbivory. Furthermore, we observed higher bite rates and greater total lengths of herbivorous fishes with greater distance from refuge habitat-responses consistent with higher perceived predation risk. Our results suggest that while the loss or fragmentation of refuge habitat reduces consumer control of resources, greater resource densities can partially counteract this effect by altering landscapes of fear of consumer species. Our findings emphasize the importance of considering the spatial context of species interactions that structure communities.

  3. Algal cell disruption using microbubbles to localize ultrasonic energy for biofuel extraction

    NASA Astrophysics Data System (ADS)

    Krehbiel, Joel; Sch, Lance; King, Daniel; Freund, Jonathan

    2014-11-01

    Cell disruption is a critical step in the production of algal-based biofuels, but current mechanical disruption methods require significant energy, typically more than actually available in the cell's oil. We propose and investigate an ultrasound disruption process using ultrasound contrast agents to localize the delivered energy. Experiments in a flow cell with focused ultrasound show a significant benefit. The degree of disruption increases with increasing peak rarefactional ultrasound pressure for pressures between 1.90 and 3.07 MPa and increasing microbubble concentration up to 12 . 5 ×107 bubbles/ml. Estimates suggest the energy of this method is less than one fourth of the energy of other industrial mechanical disruption techniques and comparable with theoretical disruption estimates. The increase in efficiency would make this technique viable for bioenergy applications.

  4. Degradation of algal organic matter using microbial fuel cells and its association with trihalomethane precursor removal.

    PubMed

    Wang, Huan; Liu, Dongmei; Lu, Lu; Zhao, Zhiwei; Xu, Yongpeng; Cui, Fuyi

    2012-07-01

    In order to provide an alternative for removal of algal organic matter (AOM) produced during algal blooms in aquatic environment, microbial fuel cell (MFC) was used to study AOM degradation and its association with THM precursor removal. The chemical oxygen demand (COD) removals in MFCs were 81 ± 6% and 73 ± 3% for AOM from Microcystis aeruginosa (AOM(M)) and Chlorella vulgaris (AOM(C)), respectively. THM precursor was also effectively degraded (AOM(M) 85 ± 2%, AOM(C) 72 ± 4%). The major AOM components (proteins, lipids, and carbohydrates) were obviously removed in MFCs. The contribution of each component to the THM formation potential (THMFP) was obtained based on calculation. The THMFP produced from soluble microbial products was very low. If the energy input during operation process was not considered, MFCs treatment could recover electrical energy of 0.29 ± 0.02 kWh/kg COD (AOM(M)) and 0.35 ± 0.06 kWh/kg COD (AOM(C)).

  5. Characteristic changes in algal organic matter derived from Microcystis aeruginosa in microbial fuel cells.

    PubMed

    Wang, Huan; Lu, Lu; Liu, Dongmei; Cui, Fuyi; Wang, Peng

    2015-11-01

    The objective of this study was to investigate behavior of algal organic matter (AOM) during bioelectrochemical oxidation in microbial fuel cell in terms of compositions and structures. Study revealed that the AOM derived from blue-green algae Microcystis aeruginosa could be degraded more completely (82% COD removal) in microbial fuel cells (MFCs) than by anaerobic fermentation (24% COD removal) in a control reactor without closed-circuit electrode and electricity was produced simultaneously. A variety of techniques were used to characterize the changes in AOM compositions and structures during bioelectrochemical oxidation. The presence of syntrophic interactions between electrochemical active bacteria and fermentative bacteria to degrade large molecular organics into small molecular substances, which could be oxidized by electrode but not by fermentation. The dominant tryptophan protein-like substances, humic acid-like substances and Chlorophyll a in AOM were highly degraded during MFC treatment.

  6. Algal culture studies related to a Closed Ecological Life Support System (CELSS)

    NASA Technical Reports Server (NTRS)

    Radmer, R. O.; Ollinger, O.; Venables, A.; Fernandez, E.

    1982-01-01

    Studies with algal cultures which relate to closed ecological life support systems (CELSS) are discussed. A description of a constant cell density apparatus for continuous culture of algae is included. Excretion of algal by-products, and nitrogen utilization and excretion are discussed.

  7. The cell recognition model in chlorolichens involving a fungal lectin binding to an algal ligand can be extended to cyanolichens.

    PubMed

    Vivas, M; Sacristán, M; Legaz, M E; Vicente, C

    2010-07-01

    Leptogium corniculatum, a cyanolichen containing Nostoc as photobiont, produces and secretes arginase to culture medium containing arginine. This secreted arginase was pre-purified by affinity chromatography on beads of activated agarose to which a polygalactosylated urease, purified from Evernia prunastri, was attached. Arginase was eluted from the beads with 50 mm alpha-d-galactose. The eluted arginase binds preferentially to the cell surface of Nostoc isolated from this lichen thallus, although it is also able to bind, to some extent, to the cell surface of the chlorobiont isolated from E. prunastri. Previous studies in chlorolichens have shown that a fungal lectin that develops subsidiary arginase activity can be a factor in recognition of compatible algal cells through binding to a polygalactosylated urease, which acts as a lectin ligand in the algal cell wall. Our experiments demonstrate that this model can now be extended to cyanolichens.

  8. Application of nano TiO2 modified hollow fiber membranes in algal membrane bioreactors for high-density algae cultivation and wastewater polishing.

    PubMed

    Hu, Weiming; Yin, Jun; Deng, Baolin; Hu, Zhiqiang

    2015-10-01

    Polyvinylidene fluoride (PVDF) hollow fiber membranes with nano-TiO2 (5% of PVDF by mass, average size = 25 nm) additives were fabricated and applied for high-density algae (Chlorella vulgaris) cultivation. At the average light intensity of 121 μmol/m(2)/s, the algal membrane bioreactors (A-MBR) operated at a hydraulic retention time of 0.5d and an average solids retention time of 25d had an average algae biomass concentration of 2350 ± 74 mg/L (in COD units) and algal biomass production rate of 6.5 ± 0.1g/m(2)/d. The A-MBRs removed an average of 78% of phosphorus from the wastewater at the initial total phosphorus concentrations ranging from 3.5 to 8.6 mg/L. The nano TiO2-embedded membranes had improved surface hydrophilicity with its total resistance about 50% lower than that of the control. This study demonstrated that PVDF/TiO2 nanocomposite membranes had a better antifouling property for high-density algae cultivation and wastewater polishing.

  9. Pitfalls, artefacts and open questions in chlorophyll thermoluminescence of leaves or algal cells.

    PubMed

    Ducruet, Jean-Marc

    2013-07-01

    Thermoluminescence of intact photosynthetic organisms, leaves or algal cells, raises specific problems. The constitutive S2/3Q B (-) B bands constitute major probes of the state of photosystem II in vivo. The presence of a dark-stable acidic lumen causes a temperature downshift of B bands, specially the S3 B band, providing a lumen pH indicator. This is accompanied by a broadening of the S3 B band that becomes an envelope of elementary B bands. The occasional AT, Q and C bands are briefly examined in an in vivo context. It is emphasized that freezing below the nucleation temperature is not necessary for physiological studies, but a source of artefacts, hence should be avoided. In intact photosynthetic structures, a dark-electron transfer from stroma reductants to the quinonic acceptors of photosystem II via the cyclic/chlororespiratory pathways, strongly stimulated by moderate warming, gives rise to the afterglow (AG) luminescence emission that reflects chloroplast energy status. The decomposition of complex TL signals into elementary bands is necessary to determine the maximum temperature T m and the area of each of them. A comparison of TL signals after 1 flash and 2 flashes prevents from confusing the three main bands observed in vivo, i.e. the S2 and S3 B bands and the AG band. Finally, the thermoluminescence bands arising sometimes above 50 °C are mentioned. The basic principles of (thermo)luminescence established on isolated thylakoids should not be applied directly without a careful examination of in vivo conditions.

  10. Secreted arginases from phylogenetically farrelated lichen species act as cross-recognition factors for two different algal cells.

    PubMed

    Legaz, María-Estrella; Fontaniella, Blanca; Millanes, Ana-María; Carlos, Vicente

    2004-08-01

    Purified arginases secreted from Evernia prunastri and Xanthoria parietina thalli hydrolyze arginine in a Mn2+ -dependent reaction. Ca2+ cannot replace Mn2+, but its addition to reaction mixtures in the presence of Mn2+ significantly inhibited arginase activity. Arginases from both lichen species also show lectin function, binding to the cell wall of both homologous and heterologous algae. Such binding is enhanced by both Ca2+ and Mn2+ and results in cytoagglutination, which is counteracted by alpha-D-galactose. A putative ligand for these lectins consists of a glycosylated urease, the polysaccharide moiety of which is uniquely composed of alpha-D-galactose. Binding of lectins inhibits its enzymatic activity, which is recovered after desorption of the lectin with alpha-D-galactose. Urease is also eluted from arginase-agarose columns by using alpha-D-galactose as eluent. Data demonstrate ligand-dependent retention of the fungal lectin on the algal cell surface and this is consistent with a model of recognition of compatible algae, through which algal cells would form a lichen with a lectin-secreting fungus only when these cells contain the specific ligand for the lectin in their cell walls. This is, lectin binding is used as a mechanism for ensuring specificity in the association.

  11. Cell density determines epithelial migration in culture.

    PubMed Central

    Rosen, P; Misfeldt, D S

    1980-01-01

    The dog kidney epithelial cell line (MDCK) has been shown to exhibit a density-correlated inhibition of growth at approxmately 6.6 X 10(5) cells per cm2. When a confluent monolayer at its maximal density was wounded by removal of a wide swath of cells, migration of the cell sheet into the denuded area occurred. Precise measurements of the rate of migration for 5 day showed that the cells accelerated at a uniform rate of 0.24 micrometer . hr-2 and, by extrapolation, possessed an apparent initial velocity of 2.8 micrometer . hr-1 at the time of wounding. The apparent initial velocity was considered to be the result of a brief (< 10 hr) and rapid acceleration dependent on cell density. To verify this, wounds were made at different densities below the maximum. In these experiments, the cells did not migrate until a "threshold" density of 2.0 X 10(5) cells per cm2 was reached regardless of the density at the time of wounding. At the threshold density, the cell sheet began to accelerate at the previously measured rate (0.24 micrometer . hr-2). Any increase in density by cell division was balanced by cell migration, so that the same threshold density was maintained by the migrating cells. Each migrating cell sustained the movement of the cell sheet at a constant rate of acceleration. It is proposed that an acceleration is, in general, characteristic of the vectorial movement of an epithelial cell sheet. Images PMID:6933523

  12. Algal-CAMs: isoforms of a cell adhesion molecule in embryos of the alga Volvox with homology to Drosophila fasciclin I.

    PubMed

    Huber, O; Sumper, M

    1994-09-15

    Proof that plants possess homologs of animal adhesion proteins is lacking. In this paper we describe the generation of monoclonal antibodies that interfere with cell-cell contacts in the 4-cell embryo of the multicellular alga Volvox carteri, resulting in a hole between the cells. The number of following cell divisions is reduced and the cell division pattern is altered drastically. Antibodies given at a later stage of embryogenesis specifically inhibit inversion of the embryo, a morphogenetic movement that turns the embryo inside out. Immunofluorescence microscopy localizes the antigen (Algal-CAM) at cell contact sites of the developing embryo. Algal-CAM is a protein with a three-domain structure: an N-terminal extensin-like domain characteristic for plant cell walls and two repeats with homology to fasciclin I, a cell adhesion molecule involved in the neuronal development of Drosophila. Alternatively spliced variants of Algal-CAM mRNA were detected that are produced under developmental control. Thus, Algal-CAM is the first plant homolog of animal adhesion proteins.

  13. Ecological risk assessment of herbicides in Japan: Integrating spatiotemporal variation in exposure and effects using a multimedia model and algal density dynamics models.

    PubMed

    Hayashi, Takehiko I; Imaizumi, Yoshitaka; Yokomizo, Hiroyuki; Tatarazako, Norihisa; Suzuki, Noriyuki

    2016-01-01

    Application of herbicides to paddy fields in Japan has strong seasonality, and their environmental concentrations exhibit clear spatiotemporal variation. The authors developed an approach that combines a multimedia environmental exposure model (Grid-Catchment Integrated Modeling System) and density dynamics models for algae. This approach enabled assessment of ecological risk when the exposure concentration shows spatiotemporal variation. First, risk maps of 5 herbicides (pretilachlor, butachlor, simetryn, mefenacet, and esprocarb) were created from the spatial predictions of environmental concentrations and 50% inhibitory concentrations of the herbicides. Simulations of algal density dynamics at high-risk sites were then conducted by incorporating the predicted temporal dynamics of the environmental concentration of each herbicide at the sites. The results suggested that the risk of pretilachlor was clearly the highest of the 5 herbicides, in terms of both the spatial distributions and the temporal durations. The present study highlights the importance of integrating exposure models and effect models to clarify spatial and temporal risk and to develop management plans for chemical exposure that shows high spatiotemporal variation.

  14. The density of apical cells of dark-grown protonemata of the moss Ceratodon purpureus

    NASA Technical Reports Server (NTRS)

    Schwuchow, J. M.; Kern, V. D.; Wagner, T.; Sack, F. D.

    2000-01-01

    Determinations of plant or algal cell density (cell mass divided by volume) have rarely accounted for the extracellular matrix or shrinkage during isolation. Three techniques were used to indirectly estimate the density of intact apical cells from protonemata of the moss Ceratodon purpureus. First, the volume fraction of each cell component was determined by stereology, and published values for component density were used to extrapolate to the entire cell. Second, protonemal tips were immersed in bovine serum albumin solutions of different densities, and then the equilibrium density was corrected for the mass of the cell wall. Third, apical cell protoplasts were centrifuged in low-osmolarity gradients, and values were corrected for shrinkage during protoplast isolation. Values from centrifugation (1.004 to 1.015 g/cm3) were considerably lower than from other methods (1.046 to 1.085 g/cm3). This work appears to provide the first corrected estimates of the density of any plant cell. It also documents a method for the isolation of protoplasts specifically from apical cells of protonemal filaments.

  15. High density cell culture system

    NASA Technical Reports Server (NTRS)

    Spaulding, Glenn F. (Inventor)

    1994-01-01

    An annular culture vessel for growing mammalian cells is constructed in a one piece integral and annular configuration with an open end which is closed by an endcap. The culture vessel is rotatable about a horizontal axis by use of conventional roller systems commonly used in culture laboratories. The end wall of the endcap has tapered access ports to frictionally and sealingly receive the ends of hypodermic syringes. The syringes permit the introduction of fresh nutrient and withdrawal of spent nutrients. The walls are made of conventional polymeric cell culture material and are subjected to neutron bombardment to form minute gas permeable perforations in the walls.

  16. Cell specific, variable density, polymer microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1977-01-01

    Biocompatible polymeric microspheres having an average diameter below about 3 microns and having density at least 15% greater or lesser than organic cells and having covalent binding sites are provided in accordance with this invention. The microspheres are obtained by copolymerizing a hydroxy or amine substituted acrylic monomer such as hydroxyethylmethacrylate with a light or dense comonomer such as a fluoromonomer. A lectin or antibody is bound to the hydroxy or amine site of the bead to provide cell specificity. When added to a cell suspension the marked bead will specifically label the cell membrane by binding to specific receptor sites thereon. The labelled membrane can then be separated by density gradient centrifugation.

  17. Algal biofuels.

    PubMed

    Razeghifard, Reza

    2013-11-01

    The world is facing energy crisis and environmental issues due to the depletion of fossil fuels and increasing CO2 concentration in the atmosphere. Growing microalgae can contribute to practical solutions for these global problems because they can harvest solar energy and capture CO2 by converting it into biofuel using photosynthesis. Microalgae are robust organisms capable of rapid growth under a variety of conditions including in open ponds or closed photobioreactors. Their reduced biomass compounds can be used as the feedstock for mass production of a variety of biofuels. As another advantage, their ability to accumulate or secrete biofuels can be controlled by changing their growth conditions or metabolic engineering. This review is aimed to highlight different forms of biofuels produced by microalgae and the approaches taken to improve their biofuel productivity. The costs for industrial-scale production of algal biofuels in open ponds or closed photobioreactors are analyzed. Different strategies for photoproduction of hydrogen by the hydrogenase enzyme of green algae are discussed. Algae are also good sources of biodiesel since some species can make large quantities of lipids as their biomass. The lipid contents for some of the best oil-producing strains of algae in optimized growth conditions are reviewed. The potential of microalgae for producing petroleum related chemicals or ready-make fuels such as bioethanol, triterpenic hydrocarbons, isobutyraldehyde, isobutanol, and isoprene from their biomass are also presented.

  18. Cell division in Apicomplexan parasites is organized by a homolog of the striated rootlet fiber of algal flagella.

    PubMed

    Francia, Maria E; Jordan, Carly N; Patel, Jay D; Sheiner, Lilach; Demerly, Jessica L; Fellows, Justin D; de Leon, Jessica Cruz; Morrissette, Naomi S; Dubremetz, Jean-François; Striepen, Boris

    2012-01-01

    Apicomplexa are intracellular parasites that cause important human diseases including malaria and toxoplasmosis. During host cell infection new parasites are formed through a budding process that parcels out nuclei and organelles into multiple daughters. Budding is remarkably flexible in output and can produce two to thousands of progeny cells. How genomes and daughters are counted and coordinated is unknown. Apicomplexa evolved from single celled flagellated algae, but with the exception of the gametes, lack flagella. Here we demonstrate that a structure that in the algal ancestor served as the rootlet of the flagellar basal bodies is required for parasite cell division. Parasite striated fiber assemblins (SFA) polymerize into a dynamic fiber that emerges from the centrosomes immediately after their duplication. The fiber grows in a polarized fashion and daughter cells form at its distal tip. As the daughter cell is further elaborated it remains physically tethered at its apical end, the conoid and polar ring. Genetic experiments in Toxoplasma gondii demonstrate two essential components of the fiber, TgSFA2 and 3. In the absence of either of these proteins cytokinesis is blocked at its earliest point, the initiation of the daughter microtubule organizing center (MTOC). Mitosis remains unimpeded and mutant cells accumulate numerous nuclei but fail to form daughter cells. The SFA fiber provides a robust spatial and temporal organizer of parasite cell division, a process that appears hard-wired to the centrosome by multiple tethers. Our findings have broader evolutionary implications. We propose that Apicomplexa abandoned flagella for most stages yet retained the organizing principle of the flagellar MTOC. Instead of ensuring appropriate numbers of flagella, the system now positions the apical invasion complexes. This suggests that elements of the invasion apparatus may be derived from flagella or flagellum associated structures.

  19. Phylogenomic Analyses Indicate that Early Fungi Evolved Digesting Cell Walls of Algal Ancestors of Land Plants.

    PubMed

    Chang, Ying; Wang, Sishuo; Sekimoto, Satoshi; Aerts, Andrea L; Choi, Cindy; Clum, Alicia; LaButti, Kurt M; Lindquist, Erika A; Yee Ngan, Chew; Ohm, Robin A; Salamov, Asaf A; Grigoriev, Igor V; Spatafora, Joseph W; Berbee, Mary L

    2015-05-14

    As decomposers, fungi are key players in recycling plant material in global carbon cycles. We hypothesized that genomes of early diverging fungi may have inherited pectinases from an ancestral species that had been able to extract nutrients from pectin-containing land plants and their algal allies (Streptophytes). We aimed to infer, based on pectinase gene expansions and on the organismal phylogeny, the geological timing of the plant-fungus association. We analyzed 40 fungal genomes, three of which, including Gonapodya prolifera, were sequenced for this study. In the organismal phylogeny from 136 housekeeping loci, Rozella diverged first from all other fungi. Gonapodya prolifera was included among the flagellated, predominantly aquatic fungal species in Chytridiomycota. Sister to Chytridiomycota were the predominantly terrestrial fungi including zygomycota I and zygomycota II, along with the ascomycetes and basidiomycetes that comprise Dikarya. The Gonapodya genome has 27 genes representing five of the seven classes of pectin-specific enzymes known from fungi. Most of these share a common ancestry with pectinases from Dikarya. Indicating functional and sequence similarity, Gonapodya, like many Dikarya, can use pectin as a carbon source for growth in pure culture. Shared pectinases of Dikarya and Gonapodya provide evidence that even ancient aquatic fungi had adapted to extract nutrients from the plants in the green lineage. This implies that 750 million years, the estimated maximum age of origin of the pectin-containing streptophytes represents a maximum age for the divergence of Chytridiomycota from the lineage including Dikarya.

  20. Algal culture studies for CELSS

    NASA Technical Reports Server (NTRS)

    Radmer, R.; Behrens, P.; Arnett, K.; Gladue, R.; Cox, J.; Lieberman, D.

    1987-01-01

    Microalgae are well-suited as a component of a Closed Environmental Life Support System (CELSS), since they can couple the closely related functions of food production and atmospheric regeneration. The objective was to provide a basis for predicting the response of CELSS algal cultures, and thus the food supply and air regeneration system, to changes in the culture parameters. Scenedesmus growth was measured as a function of light intensity, and the spectral dependence of light absorption by the algae as well as algal respiration in the light were determined as a function of cell concentration. These results were used to test and confirm a mathematical model that describes the productivity of an algal culture in terms of the competing processes of photosynthesis and respiration. The relationship of algal productivity to cell concentration was determined at different carbon dioxide concentrations, temperatures, and light intensities. The maximum productivity achieved by an air-grown culture was found to be within 10% of the computed maximum productivity, indicating that CO2 was very efficiently removed from the gas stream by the algal culture. Measurements of biomass productivity as a function of cell concentration at different light intensities indicated that both the productivity and efficiency of light utilization were greater at higher light intensities.

  1. Identification of cell density signal molecule

    DOEpatents

    Schwarz, R.I.

    1998-04-21

    Disclosed herein is a novel proteinaceous cell density signal molecule (CDS) between 25 and 35 kD, which is secreted by fibroblastic primary avian tendon cells in culture, and causes the cells to self-regulate their proliferation and the expression of differentiated function. It effects an increase of procollagen production in avian tendon cell cultures of ten fold while proliferation rates are decreased. CDS, and the antibodies which recognize them, are important for the development of diagnostics and treatments for injuries and diseases involving connective tissues, particularly tendon. Also disclosed are methods of production and use. 2 figs.

  2. Identification of cell density signal molecule

    DOEpatents

    Schwarz, Richard I.

    1998-01-01

    Disclosed herein is a novel proteinaceous cell density signal molecule (CDS) between 25 and 35 kD, which is secreted by fibroblastic primary avian tendon cells in culture, and causes the cells to self-regulate their proliferation and the expression of differentiated function. It effects an increase of procollagen production in avian tendon cell cultures of ten fold while proliferation rates are decreased. CDS, and the antibodies which recognize them, are important for the development of diagnostics and treatments for injuries and diseases involving connective tissues, particularly tendon. Also disclosed are methods of production and use.

  3. Cell specific, variable density, polymer microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1978-01-01

    Biocompatible polymeric microspheres having an average diameter below about 3 microns and having a density at least 15% greater or lesser than organic cells and having covalent binding sites are provided in accordance with this invention. The microspheres are obtained by copolymerizing a hydroxy or amine substituted acrylic monomer such as hydroxyethylmethacrylate with a light or dense comonomer such as a fluoromonomer. A lectin or antibody is bound to the hydroxy or amine site of the bead to provide cell specificity. When added to a cell suspension the marked bead will specifically label the cell membrane by binding to specific receptor sites thereon. The labelled membrane can then be separated by density gradient centrifugation.

  4. High power density solid oxide fuel cells

    DOEpatents

    Pham, Ai Quoc; Glass, Robert S.

    2004-10-12

    A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O (LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.

  5. Harmful Algal Bloom Webinar

    EPA Pesticide Factsheets

    The problem is complex. Excessive nitrogen and phosphorous levels can cause harmful algal blooms. Different algal/cyanobacteria strains bloom under different conditions. Different strains produce different toxins at varying amounts.

  6. Mechanism of Algal Aggregation by Bacillus sp. Strain RP1137

    PubMed Central

    Powell, Ryan J.

    2014-01-01

    Alga-derived biofuels are one of the best alternatives for economically replacing liquid fossil fuels with a fungible renewable energy source. Production of fuel from algae is technically feasible but not yet economically viable. Harvest of dilute algal biomass from the surrounding water remains one of the largest barriers to economic production of algal biofuel. We identified Bacillus sp. strain RP1137 in a previous study and showed that this strain can rapidly aggregate several biofuel-producing algae in a pH- and divalent-cation-dependent manner. In this study, we further characterized the mechanism of algal aggregation by RP1137. We show that aggregation of both algae and bacteria is optimal in the exponential phase of growth and that the density of ionizable residues on the RP1137 cell surface changes with growth stage. Aggregation likely occurs via charge neutralization with calcium ions at the cell surface of both algae and bacteria. We show that charge neutralization occurs at least in part through binding of calcium to negatively charged teichoic acid residues. The addition of calcium also renders both algae and bacteria more able to bind to hydrophobic beads, suggesting that aggregation may occur through hydrophobic interactions. Knowledge of the aggregation mechanism may enable engineering of RP1137 to obtain more efficient algal harvesting. PMID:24771029

  7. Development and optimization of biofilm based algal cultivation

    NASA Astrophysics Data System (ADS)

    Gross, Martin Anthony

    This dissertation describes research done on biofilm based algal cultivation systems. The system that was developed in this work is the revolving algal biofilm cultivation system (RAB). A raceway-retrofit, and a trough-based pilot-scale RAB system were developed and investigated. Each of the systems significantly outperformed a control raceway pond in side-by-side tests. Furthermore the RAB system was found to require significantly less water than the raceway pond based cultivation system. Lastly a TEA/LCA analysis was conducted to evaluate the economic and life cycle of the RAB cultivation system in comparison to raceway pond. It was found that the RAB system was able to grow algae at a lower cost and was shown to be profitable at a smaller scale than the raceway pond style of algal cultivation. Additionally the RAB system was projected to have lower GHG emissions, and better energy and water use efficiencies in comparison to a raceway pond system. Furthermore, fundamental research was conducted to identify the optimal material for algae to attach on. A total of 28 materials with a smooth surface were tested for initial cell colonization and it was found that the tetradecane contact angle of the materials had a good correlation with cell attachment. The effects of surface texture were evaluated using mesh materials (nylon, polypropylene, high density polyethylene, polyester, aluminum, and stainless steel) with openings ranging from 0.05--6.40 mm. It was found that both surface texture and material composition influence algal attachment.

  8. Mechanism of algal aggregation by Bacillus sp. strain RP1137.

    PubMed

    Powell, Ryan J; Hill, Russell T

    2014-07-01

    Alga-derived biofuels are one of the best alternatives for economically replacing liquid fossil fuels with a fungible renewable energy source. Production of fuel from algae is technically feasible but not yet economically viable. Harvest of dilute algal biomass from the surrounding water remains one of the largest barriers to economic production of algal biofuel. We identified Bacillus sp. strain RP1137 in a previous study and showed that this strain can rapidly aggregate several biofuel-producing algae in a pH- and divalent-cation-dependent manner. In this study, we further characterized the mechanism of algal aggregation by RP1137. We show that aggregation of both algae and bacteria is optimal in the exponential phase of growth and that the density of ionizable residues on the RP1137 cell surface changes with growth stage. Aggregation likely occurs via charge neutralization with calcium ions at the cell surface of both algae and bacteria. We show that charge neutralization occurs at least in part through binding of calcium to negatively charged teichoic acid residues. The addition of calcium also renders both algae and bacteria more able to bind to hydrophobic beads, suggesting that aggregation may occur through hydrophobic interactions. Knowledge of the aggregation mechanism may enable engineering of RP1137 to obtain more efficient algal harvesting.

  9. High power density carbonate fuel cell

    SciTech Connect

    Yuh, C.; Johnsen, R.; Doyon, J.; Allen, J.

    1996-12-31

    Carbonate fuel cell is a highly efficient and environmentally clean source of power generation. Many organizations worldwide are actively pursuing the development of the technology. Field demonstration of multi-MW size power plant has been initiated in 1996, a step toward commercialization before the turn of the century, Energy Research Corporation (ERC) is planning to introduce a 2.85MW commercial fuel cell power plant with an efficiency of 58%, which is quite attractive for distributed power generation. However, to further expand competitive edge over alternative systems and to achieve wider market penetration, ERC is exploring advanced carbonate fuel cells having significantly higher power densities. A more compact power plant would also stimulate interest in new markets such as ships and submarines where space limitations exist. The activities focused on reducing cell polarization and internal resistance as well as on advanced thin cell components.

  10. Integrated Bacillus sp. immobilized cell reactor and Synechocystis sp. algal reactor for the treatment of tannery wastewater.

    PubMed

    Sekaran, G; Karthikeyan, S; Nagalakshmi, C; Mandal, A B

    2013-01-01

    The wastewater discharged from leather industries lack biodegradability due to the presence of xenobiotic compounds. The primary clarification and aerobic treatment in Bacillus sp. immobilized Chemo Autotrophic Activated Carbon Oxidation (CAACO) reactor removed considerable amount of pollution parameters. The residual untreated organics in the wastewater was further treated in algal batch reactor inoculated with Synechocystis sp. Sodium nitrate, K(2)HPO(4), MgSO(4).7H(2)O, NH(4)Cl, CaCl(2)·2H(2)O, FeCl(3) (anhydrous), and thiamine hydrochloride, rice husk based activated carbon (RHAC), immobilization of Bacillus sp. in mesoporous activated carbon, sand filter of dimensions diameter, 6 cm and height, 30 cm; and the CAACO reactor of dimensions diameter, 5.5 cm and height, 30 cm with total volume 720 ml, and working volume of 356 ml. In the present investigation, the CAACO treated tannery wastewater was applied to Synechocystis sp. inoculated algal batch reactor of hydraulic residence time 24 h. The BOD(5), COD, and TOC of treated wastewater from algal batch reactor were 20 ± 7, 167 ± 29, and 78 ± 16 mg/l respectively. The integrated CAACO system and Algal batch reactor was operated for 30 days and they accomplished a cumulative removal of BOD(5),COD, TOC, VFA and sulphide as 98 %, 95 %, 93 %, 86 %, and 100 %, respectively. The biokinetic constants for the growth of algae in the batch reactor were specific growth rate, 0.095(day(-1)) and yield coefficient, 3.15 mg of algal biomass/mg of COD destructed. The degradation of xenobiotic compounds in the algal batch reactor was confirmed through HPLC and FT-IR techniques. The integrated CAACO-Algal reactor system established a credible reduction in pollution parameters in the tannery wastewater. The removal mechanism is mainly due to co-metabolism between algae and bacterial species and the organics were completely metabolized rather than by adsorption.

  11. High energy density aluminum-oxygen cell

    NASA Technical Reports Server (NTRS)

    Rudd, E. J.; Gibbons, D. W.

    1993-01-01

    An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell. An example of this is the metal-air fuel cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, having high energy and power densities, being environmentally acceptable, and having a large, established industrial base for production and distribution. An aluminum-oxygen system is currently under development for a UUV test vehicle, and recent work has focussed upon low corrosion aluminum alloys and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from S to 150 mA/sq cm have been identified. These materials are essential to realizing an acceptable mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 hours in a large scale, half-cell system.

  12. High Energy Density aluminum/oxygen cell

    NASA Astrophysics Data System (ADS)

    Rudd, E. J.; Gibbons, D. W.

    An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell, an example of which is the metal/air cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, with high energy and power densities, environmentally acceptable and having a large, established industrial base for production and distribution. An aluminum/oxygen system is currently under development for a prototype unmanned, undersea vehicle (UUV) for the US navy and recent work has focussed upon low corrosion aluminum alloys, and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from 5 to 150 mA/cm 2 have been identified, such materials being essential to realize mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 h in a large scale, half-cell system.

  13. High energy density aluminum-oxygen cell

    NASA Astrophysics Data System (ADS)

    Rudd, E. J.; Gibbons, D. W.

    1993-11-01

    An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell. An example of this is the metal-air fuel cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, having high energy and power densities, being environmentally acceptable, and having a large, established industrial base for production and distribution. An aluminum-oxygen system is currently under development for a UUV test vehicle, and recent work has focussed upon low corrosion aluminum alloys and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from S to 150 mA/sq cm have been identified. These materials are essential to realizing an acceptable mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 hours in a large scale, half-cell system.

  14. Prechlorination of algae-laden water: The effects of transportation time on cell integrity, algal organic matter release, and chlorinated disinfection byproduct formation.

    PubMed

    Qi, Jing; Lan, Huachun; Liu, Ruiping; Miao, Shiyu; Liu, Huijuan; Qu, Jiuhui

    2016-10-01

    The prechlorination-induced algal organic matter (AOM) released from Microcystis aeruginosa (M. aeruginosa) cells has been reported to serve as a source of precursors for chlorinated disinfection byproducts (DBPs). However, previous studies have mainly focused on the precursors either extracted directly from the cell suspension or derived immediately after algal suspension prechlorination. This study aims to investigate the impacts of water transportation time after algal suspension prechlorination on cell integrity, AOM release, and DBP formation during the dissolved phase chlorination. The damage to cell integrity after prechlorination was indicated to depend not only on chlorine dose but also on transportation time. The highest dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) values were observed at 2 mg/L chlorine preoxidation before transportation, but were obtained at 0.4 mg/L chlorine after 480-min simulated transportation. The variation of DON with transportation time was indicated to be mainly influenced by the small molecular weight nitrogenous organic compounds, such as amino acids. Additionally, formation of the corresponding chlorinated carbonaceous disinfection byproducts (C-DBPs) and nitrogenous disinfection byproducts (N-DBPs) during the dissolved phase chlorination showed the same variation tendency as DOC and DON respectively. The highest C-DBP (98.4 μg/L) and N-DBP (5.5 μg/L) values were obtained at 0.4 mg/L chlorine preoxidation after 480-min simulated transportation. Therefore, when prechlorination is applied for algae-laden water pretreatment, not only chlorine dose but also transportation time needs to be considered with regard to their effects on cell integrity, AOM release, and chlorinated DBP formation.

  15. Cell size and the blockage of electron transfer in photosynthesis: proposed endpoints for algal assays and its application to soil alga Chlorococcum infusionum.

    PubMed

    Nam, Sun-Hwa; An, Youn-Joo

    2015-06-01

    This study evaluated multiple endpoints of algal assays to identify sensitive and easy to use endpoints that could be applied to evaluate algal toxicity in metal-polluted soil extracts. Soil algae play an important role in trophic levels; thus, Chlorococcum infusionum was selected as the test species. Soil extracts were used because they might help identify potential soil retention and ecological hazards caused by pollutants that are present in the soil aqueous phase. The multi-endpoints measured were growth yield, photosynthetic activities, and cell viabilities. Nine parameters were measured to evaluate photosynthetic activity; namely, specific energy fluxes per quinone A-reducing photosystem II reaction center (absorption flux, trapped energy flux, electron transport flux, and dissipated energy flux per reaction center), quantum yields (maximum quantum yield of primary photochemistry, quantum yield of electron transport, quantum yield of energy dissipation, and average quantum yield of primary photochemistry), and the blockage of electron transfer from the reaction center to the quinone pool. Cell viability was evaluated by measuring cell size, cell granularity, and the autofluorescence of chlorophyll using flow cytometry. The results showed that heavy metals reduced growth yield, cell viability, and the photosynthetic activity of C. infusionum in soil extracts. Out of the 13 tested endpoints, the blockage of electron transfer from the reaction center to the quinone pool and cell size represented the most sensitive endpoints. We propose that both endpoints should be measured, along with conventional growth yield, to determine the effect of soil pollutants and to lower pollutant concentrations in soils.

  16. Cyanobacteria Toxin and Cell Propagation through Seven Lake Erie Treatment Plants during the 2013 Algal Bloom Season - abstract

    EPA Science Inventory

    Over the past five years, Lake Erie has been experiencing harmful algal blooms (HABs) of progressively increasing severity. Cognizant of the potential health and economic impacts, the United States Environmental Protection Agency’s (USEPA’s) Water Supply and Water Resources Divis...

  17. Tracking the spectroscopic and chromatographic changes of algal derived organic matter in a microbial fuel cell.

    PubMed

    Hur, Jin; Lee, Bo-Mi; Choi, Kwang-Soon; Min, Booki

    2014-02-01

    Changes in the characteristics of algae-derived organic matter (AOM) were examined upon the operation of a microbial fuel cell (MFC) using multiple analytical methods. Temporal variations in the UV absorption and fluorescence excitation-emission matrix of the AOM revealed that less condensed humic-like components and large-sized protein-like fluorescent compounds were preferentially decomposed over the period of electricity generation. They also showed that low UV-absorbing extracellular organic matters (EOM) were produced at the end of the operation. SEC chromatograms demonstrated that smaller-sized UV-absorbing components were initially decomposed, followed by the net production of EOM with an intermediate molecular weight. Fourier transform infrared (FT-IR) spectra showed that proteins and polysaccharides were the two most dominant structures of the AOM in the MFC. Two-dimensional correlation spectroscopy combined with FT-IR provided additional valuable information on the sequential changes of the AOM, which occurred in the order of proteins → acidic functional groups → polysaccharides → amino acids/proteins.

  18. Heterologous activation of the Porphyra tenera HSP70 promoter in Bangiophycean algal cells.

    PubMed

    Hirata, Ryo; Jeong, Won-Joong; Saga, Naotsune; Mikami, Koji

    2011-01-01

    Porphyra has attracted great attention for its biological and industrial importance. However, establishment of a stable nuclear transformation has not yet been achieved in these organisms, which impedes the molecular biological study and the development of a molecular breeding method for them. Toward establishing the stable transformation, we have recently developed an efficient transient gene expression system in Bangiophycean algae, in which the HSP70 promoter from P. tenera (PtHSP70 promoter) was activated heterologously in P. yezoensis cells. Since heterologous promoters are required for homologous recombination-based stable transformation, the identification of heterologously activated promoters is important in establishing a stable transformation system in individual Bangiophycean alga. We here examined the activation of the PtHSP70 promoter using the GC-rich PyGUS reporter system in additional Porphyra and Bangia species. The results indicated that this promoter drove expression of the PyGUS gene efficiently in all examined algae, whereas there was quite low expression of PyGUS by the cauliflower mosaic virus 35S promoter that is widely used as a heterologous promoter in the transformation of green land plants. Therefore, heterologous activation of the PtHSP70 promoter could promote the establishment of the stable transformation system in various kinds of Bangiophycean algae.

  19. Algal Systems for Hydrogen Photoproduction

    SciTech Connect

    Ghirardi, Maria L

    2015-10-08

    The National Renewable Energy Laboratory (NREL), under the guidance of Drs. Michael Seibert (retired, Fellow Emeritus) and Maria Ghirardi (Fellow), led 15 years of research addressing the issue of algal H2 photoproduction. This project resulted in greatly increased rates and yields of algal hydrogen production; increased understanding of the H2 metabolism in the green alga, Chlamydomonas reinhardtii; expanded our knowledge of other physiological aspects relevant to sustained algal photosynthetic H2 production; led to the genetic identification, cloning and manipulation of algal hydrogenase genes; and contributed to a broader, fundamental understanding of the technical and scientific challenges to improving the conversion efficiencies in order to reach the U.S. Department of Energy’s Fuel Cell Technologies Office’s targets. Some of the tangible results are: (i) 64 publications and 6 patents, (ii) international visibility to NREL, (iii) reinvigoration of national and international biohydrogen research, and (iv) research progress that helped stimulate new funding from other DOE and non-DOE programs, including the AFOSR and the DOE Office of Science.

  20. Structural Impacts on Thallus and Algal Cell Components of Two Lichen Species in Response to Low-Level Air Pollution in Pacific Northwest Forests

    NASA Astrophysics Data System (ADS)

    Ra, Hyung-Shim Y.; Rubin, Laura; Crang, Richard F. E.

    2004-04-01

    Lichens have long been regarded as bioindicators of air pollution, and structural studies typically have indicated negative impacts in highly polluted areas. In this research, Parmelia sulcata and Platismatia glauca were collected from one clean and two polluted sites in the Pacific Northwest forests of the United States to investigate the anatomical and ultrastructural responses of relatively resistant lichens to moderate air pollution. Light microscopy of polluted materials revealed only slight increases in the algal cell proportions of the thallus, and a decrease in the fungal cells of the medulla. Using transmission electron microscopy, increased lipid droplets in the cytoplasm and an increase in the cell wall thickness of the photobionts were found in the polluted lichens. These results were compared with physiological data in which the net carbon uptake did not show any significant differences; however, the total chlorophyll content was heightened in the polluted samples. The increased total chlorophyll content and the absence of any changes in the algal cell proportions of the polluted samples suggest that the photobionts possessed a higher chlorophyll content per unit volume of the photobiont at polluted sites. The results also indicate that lichens have altered their storage allocation in different cellular compartments. This may be a result of symbiotic readjustment(s) between the photobiont and the mycobiont. In comparison with the physiological results from these two species, these changes do not represent damaging effects by low-level air pollution.

  1. X-ray microanalysis of calcium in fixed and in shock-frozen hydrated green algal cells: Mougeotia, Spirogyra and Zygnema

    NASA Astrophysics Data System (ADS)

    Rossbacher, Roland; Wagner, Gottfried; Pallaghy, Charles K.

    1984-04-01

    X-ray microanalysis, widely used for ionic detection in cell tissues, was performed on 0.5 μm thick glutaraldehyde-osmiumtetroxide fixed cell sections. Calcium in a water-insoluble state was found in membrane bound vesicles of about 0.5 μm in diameter. No other cell compartment showed a comparable calcium accumulation. In vivo staining by the fluorescent calcium indicator dye chlorotetracycline revealed a vesicular calcium pattern in Mougeotia matching the results by X-ray microanalysis: a dense population of calcium vesicles is located close to the chloroplast edge where the actin filaments are attached. The data find further support from X-ray microanalysis of shock-frozen hydrated Mougeotia cells and of the closely related green algal cells Spirogyra and Zygnema (Zygnemaceae). X-ray microanalysis as performed in this study seems a reliable tool for the detection of water-insoluble calcium stored by membrane-covered cytoplasmic compartments.

  2. Microvessel and astroglial cell densities in the mouse hippocampus.

    PubMed Central

    Shimada, M; Akagi, N; Goto, H; Watanabe, H; Nakanishi, M; Hirose, Y; Watanabe, M

    1992-01-01

    In order to study the factors responsible for glucose uptake in the mouse hippocampus, microvessel and astroglial cell densities were measured and compared in each laminal region. Microvessel density was examined on histologically prepared sections after injection of Indian ink and measured by means of an image analyser. Astroglial cell density was determined after the cells were stained immunohistochemically. Microvessel and astroglial cell densities were determined in 10 different hippocampal structures. Microvessel and astroglial cell densities were strongly correlated in all layers except the pyramidal cell layers. The highest density of perfused microvessels was found in the stratum lacunosum-moleculare, compared with other regions, and the lowest values were found in the stratum lucidum and dentate granular cell layer. Among pyramidal cell layers, microvessel density in sector CA3a was significantly higher than that in CA1. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:1452486

  3. Mechanism and challenges in commercialisation of algal biofuels.

    PubMed

    Singh, Anoop; Nigam, Poonam Singh; Murphy, Jerry D

    2011-01-01

    Biofuels made from algal biomass are being considered as the most suitable alternative energy in current global and economical scenario. Microalgae are known to produce and accumulate lipids within their cell mass which is similar to those found in many vegetable oils. The efficient lipid producer algae cell mass has been reported to contain more than 30% of their cell weight as lipids. According to US DOE microalgae have the potential to produce 100 times more oil per acre land than any terrestrial plants. This article reviews up to date literature on the composition of algae, mechanism of oil droplets, triacylglycerol (TAG) production in algal biomass, research and development made in the cultivation of algal biomass, harvesting strategies, and recovery of lipids from algal mass. The economical challenges in the production of biofuels from algal biomass have been discussed in view of the future prospects in the commercialisation of algal fuels.

  4. Undifferentiated murine embryonic stem cells used to model the effects of the blue-green algal toxin cylindrospermopsin on preimplantation embryonic cell proliferation.

    PubMed

    Reid, Katherine J; Lang, Kenneth; Froscio, Suzanne; Humpage, Andrew J; Young, Fiona M

    2015-11-01

    Undifferentiated mouse embryonic stem cell (mES) proliferation in vitro resembles aspects of in vivo pre-implantation embryonic development. mES were used to assess the embryo-toxicity of cylindrospermopsin (CYN), a water contaminant with an Australian Drinking Water Guideline (ADWG) of 1 μg/L. mES exposed to 0-1 μg/mL CYN for 24-168 h were subjected to an optimised crystal violet viability assay. mES exposed to retinoic acid ± 1 μg/L CYN differentiated into neural-like cells confirmed by morphological examination and RT-PCR for Oct4, Brachyury and Nestin. The CYN No Observed Effect Concentration (OEC) was 0.5 μg/mL, the Lowest OEC was 1 μg/mL (p < 0.001, n = 3), and the IC50 was 0.86 μg/mL after 24 h. The ADWG 1 μg/L CYN did not affect differentiation or proliferation after 72 h, but decreased proliferation after 168 h (p < 0.05). We conclude that higher algal bloom-associated CYN concentrations have the potential to impair in vivo pre-implantation development, and the mES crystal violet assay has broad application to screening environmental toxins.

  5. Recent Advances in Algal Genetic Tool Development

    SciTech Connect

    R. Dahlin, Lukas; T. Guarnieri, Michael

    2016-06-24

    The goal of achieving cost-effective biofuels and bioproducts derived from algal biomass will require improvements along the entire value chain, including identification of robust, high-productivity strains and development of advanced genetic tools. Though there have been modest advances in development of genetic systems for the model alga Chlamydomonas reinhardtii, progress in development of algal genetic tools, especially as applied to non-model algae, has generally lagged behind that of more commonly utilized laboratory and industrial microbes. This is in part due to the complex organellar structure of algae, including robust cell walls and intricate compartmentalization of target loci, as well as prevalent gene silencing mechanisms, which hinder facile utilization of conventional genetic engineering tools and methodologies. However, recent progress in global tool development has opened the door for implementation of strain-engineering strategies in industrially-relevant algal strains. Here, we review recent advances in algal genetic tool development and applications in eukaryotic microalgae.

  6. Possible importance of algal toxins in the Salton Sea, California

    USGS Publications Warehouse

    Reifel, K.M.; McCoy, M.P.; Rocke, T.E.; Tiffany, M.A.; Hurlbert, S.H.; Faulkner, D.J.

    2002-01-01

    In response to wildlife mortality including unexplained eared grebe (Podiceps nigricollis) die-off events in 1992 and 1994 and other mortality events including large fish kills, a survey was conducted for the presence of algal toxins in the Salton Sea. Goals of this survey were to determine if and when algal toxins are present in the Salton Sea and to describe the phytoplankton composition during those times. A total of 29 samples was collected for toxicity analysis from both nearshore and midlake sites visited biweekly from January to December 1999. Dinoflagellates and diatoms dominated most samples, but some were dominated by a prymnesiophyte (Pleurochrysis pseudoroscoffensis) or a raphidophyte (Chattonella marina). Several types of blooms were observed and sampled. The dinoflagellate Gyrodinium uncatenum formed an extensive, dense (up to 310 000 cells ml-1) and long-lasting bloom during the winter in 1999. A coccolithophorid, Pleurochrysis pseudoroscoffensis, occurred at high densities in surface films and nearshore areas during the spring and summer of 1999. These surface films also contained high densities of one or two other species (an unidentified scrippsielloid, Heterocapsa niei, Chattonella marina). Localized blooms were also observed in the Salton Sea. An unknown small dinoflagellate reached high densities (110 000 cells ml-1) inside Varner Harbor, and an unidentified species of Gymnodinium formed a dense (270 000 cells ml-1) band along part of the southern shoreline during the summer. Three species known to produce toxins in other systems were found. Protoceratium reticulatum (=Gonyaulax grindleyi) and Chattonella marina were found in several samples taken during summer months, and Prorocentrum minimum was found in low densities in several samples. Extracts of most samples, including those containing known toxic species, showed a low level (<10% mortality across all concentrations) of activity in the brine shrimp lethality assay and were not considered

  7. Detection of algal lipid accumulation due to nitrogen limitation via dielectric spectroscopy of Chlamydomonas reinhardtii suspensions in a coaxial transmission line sample cell.

    PubMed

    Bono, Michael S; Ahner, Beth A; Kirby, Brian J

    2013-09-01

    In this study, dielectric characterization of algae cell suspensions was used to detect lipid accumulation due to nitrogen starvation. Wild-type Chlamydomonas reinhardtii (CC-125) was cultivated in replete and nitrogen-limited conditions in order to achieve a range of lipid contents, as confirmed by Nile Red fluorescence measurements. A vector network analyzer was used to measure the dielectric scattering parameters of a coaxial region of concentrated cell suspension. The critical frequency fc of the normalized transmission coefficient |S21(*)| decreased with increasing lipid content but did not change with cell concentration. These observations were consistent with a decrease in cytoplasmic conductivity due to lipid accumulation in the preliminary transmission line model. This dielectric sensitivity to lipid content will facilitate the development of a rapid, noninvasive method for algal lipid measurement that could be implemented in industrial settings without the need for specialized staff and analytical facilities.

  8. High Efficiency, High Density Terrestrial Panel. [for solar cell modules

    NASA Technical Reports Server (NTRS)

    Wohlgemuth, J.; Wihl, M.; Rosenfield, T.

    1979-01-01

    Terrestrial panels were fabricated using rectangular cells. Packing densities in excess of 90% with panel conversion efficiencies greater than 13% were obtained. Higher density panels can be produced on a cost competitive basis with the standard salami panels.

  9. Atmosphere stabilization and element recycle in an experimental mouse-algal system

    NASA Technical Reports Server (NTRS)

    Smernoff, David T.

    1986-01-01

    Life support systems based on bioregeneration rely on the control and manipulation of organisms. Experiments conducted with a gas-closed mouse-algal system designed to investigate principles of photosynthetic gas exchange focus primarily on observing gas exchange phenomena under varying algal environmental conditions and secondarily on studying element cycling through compartments of the experimental system. Inherent instabilities exit between the uptake and release of carbon dioxide CO2 and oxygen O2 by the mouse and algae. Variations in light intensity and cell density alter the photosynthetic rate of the algae and enable maintenance of physiologic concentrations of CO2 and O2. Different nitrogen sources (urea and nitrate) result in different algal assimilatory quotients (AQ). Combinations of photosynthetic rate and AQ ratio manipulations have been examined for their potential in stabilizing atmospheric gas concentrations in the gas-closed algal-mouse system. Elemental mass balances through the experimental systems compartments are being studied with the concurrent development of a mathematical simulation model. Element cycling experiments include quantification of elemental flows through system compartments and wet oxidation of system waste materials for use as an algal nutrient source. Oxidized waste products demonstrate inhibitory properties although dilution has been shown to allow normal growth.

  10. Harmful Algal Blooms

    USGS Publications Warehouse

    Graham, Jennifer L.

    2007-01-01

    What are Harmful Algal Blooms (HABs)? Freshwater and marine harmful algal blooms (HABs) can occur anytime water use is impaired due to excessive accumulations of algae. HAB occurrence is affected by a complex set of physical, chemical, biological, hydrological, and meteorological conditions making it difficult to isolate specific causative environmental factors. Potential impairments include reduction in water quality, accumulation of malodorous scums in beach areas, algal production of toxins potent enough to poison both aquatic and terrestrial organisms, and algal production of taste-and-odor compounds that cause unpalatable drinking water and fish. HABs are a global problem, and toxic freshwater and (or) marine algae have been implicated in human and animal illness and death in over 45 countries worldwide and in at least 27 U.S. States (Yoo and others, 1995; Chorus and Bartram, 1999; Huisman and others, 2005).

  11. Indicators: Algal Toxins (microcystin)

    EPA Pesticide Factsheets

    Algal toxins are toxic substances released by some types of algae (phytoplankton) when they are present in large quantities (blooms) and decay or degrade. High nutrient levels and warm temperatures often result in favorable conditions for algae blooms.

  12. No-observed-effect concentrations in batch and continuous algal toxicity tests

    SciTech Connect

    Chao, M.R.; Chen, C.Y.

    2000-06-01

    In this study, the authors compare the no-observed-effect concentrations (NOECs) of Cd, Ni, Zn, Cu, and Pb based on different response parameters, using batch and continuous algal toxicity tests. For both batch and continuous tests, parameters based on total cell volume (TCV) were found to be less sensitive than those related to cell densities. The above observation mainly occurred because, under the stresses from metal toxicants evaluated in this and a previous study, the mean cell volume (MCV) of algae increased considerably. The increase of MCV compensates for the effects brought about by the reduction in cell density and eventually results in less variation in TCVs. This study shows that parameters based on cell density are quite sensitive and ideal for the estimation of NOECs. In addition, comparison of the NOEC values derived from different culture techniques shows that the continuous methods generally yields lower NOEC values than that obtained by the batch tests. The results of this study also indicate that the NOEC provides more protection to the test organism than the effective concentration at 10% growth reduction (EC10). For toxicity test methods that produce small variations among replicates, the NOEC is still a good indicator of low toxic effect. Furthermore, for the continuous algal toxicity test, a relatively simple approach is proposed to determine the NOEC values based on the algal culture's control charts. The proposed method produced identical results as those based on conventional hypothesis-testing methods.

  13. High resolution imaging of the ultrastructure of living algal cells using soft x-ray contact microscopy

    SciTech Connect

    Ford, T.W.; Cotton, R.A.; Page, A.M.; Tomie, T.; Majima, T.; Stead, A.D.

    1995-12-31

    Soft x-ray contact microscopy provides the biologist with a technique for examining the ultrastructure of living cells at a much higher resolution than that possible by various forms of light microscopy. Readout of the developed photoresist using atomic force microscopy (AFM) produces a detailed map of the carbon densities generated in the resist following exposure of the specimen to water-window soft x-rays (2--4nm) produced by impact of a high energy laser onto a suitable target. The established high resolution imaging method of transmission electron microscopy (TEM) has inherent problems in the chemical pre-treatment required for producing the ultrathin sections necessary for this technique. Using the unicellular green alga Chlamydomonas the ultrastructural appearance of the cells following SXCM and TEM has been compared. While SXCM confirms the basic structural organization of the cell as seen by TEM (e.g., the organization of the thylakoid membranes within the chloroplast; flagellar insertion into the cytoplasm), there are important differences. These are in the appearance of the cell covering and the presence of carbon-dense spherical cellular inclusions.

  14. Pretreatment of algae-laden and manganese-containing waters by oxidation-assisted coagulation: Effects of oxidation on algal cell viability and manganese precipitation.

    PubMed

    Lin, Jr-Lin; Hua, Lap-Cuong; Wu, Yuting; Huang, Chihpin

    2016-02-01

    Preoxidation is manipulated to improve performance of algae and soluble manganese (Mn) removal by coagulation-sedimentation for water treatment plants (WTPs) when large amount of soluble Mn presents in algae-laden waters. This study aimed to investigate the effects of preoxidation on the performance of coagulation-sedimentation for the simultaneous removal of algae and soluble Mn, including ionic and complexed Mn. NaOCl, ClO2, and KMnO4 were used to pretreat such algae-laden and Mn containing waters. The variation of algal cell viability, residual cell counts, and concentrations of Mn species prior to and after coagulation-sedimentation step were investigated. Results show that NaOCl dosing was effective in reducing the viability of algae, but precipitated little Mn. ClO2 dosing had a strongest ability to lower algae viability and oxidize ionic and complexed soluble Mn, where KMnO4 dosing oxidized ionic and complexed Mn instead of reducing the viability of cells. Preoxidation by NaOCl only improved the algae removal by sedimentation, whereas most of soluble Mn still remained. On the other hand, ClO2 preoxidation substantially improved the performance of coagulation-sedimentation for simultaneous removal of algae and soluble Mn. Furthermore, KMnO4 preoxidation did improve the removal of algae by sedimentation, but left significant residual Mn in the supernatant. Images from FlowCAM showed changes in aspect ratio (AR) and transparency of algae-Mn flocs during oxidation-assisted coagulation, and indicates that an effective oxidation can improve the removal of most compact algae-Mn flocs by sedimentation. It suggests that an effective preoxidation for reducing algal cell viability and the concentration of soluble Mn is a crucial step for upgrading the performance of coagulation-sedimentation.

  15. Algal recycling enhances algal productivity and settleability in Pediastrum boryanum pure cultures.

    PubMed

    Park, Jason B K; Craggs, Rupert J; Shilton, Andy N

    2015-12-15

    Recycling a portion of gravity harvested algae (i.e. algae and associated bacteria biomass) has been shown to improve both algal biomass productivity and harvest efficiency by maintaining the dominance of a rapidly-settleable colonial alga, Pediastrum boryanum in both pilot-scale wastewater treatment High Rate Algal Ponds (HRAP) and outdoor mesocosms. While algal recycling did not change the relative proportions of algae and bacteria in the HRAP culture, the contribution of the wastewater bacteria to the improved algal biomass productivity and settleability with the recycling was not certain and still required investigation. P. boryanum was therefore isolated from the HRAP and grown in pure culture on synthetic wastewater growth media under laboratory conditions. The influence of recycling on the productivity and settleability of the pure P. boryanum culture was then determined without wastewater bacteria present. Six 1 L P. boryanum cultures were grown over 30 days in a laboratory growth chamber simulating New Zealand summer conditions either with (Pr) or without (Pc) recycling of 10% of gravity harvested algae. The cultures with recycling (Pr) had higher algal productivity than the controls (Pc) when the cultures were operated at both 4 and 3 d hydraulic retention times by 11% and 38% respectively. Furthermore, algal recycling also improved 1 h settleability from ∼60% to ∼85% by increasing the average P. boryanum colony size due to the extended mean cell residence time and promoted formation of large algal bio-flocs (>500 μm diameter). These results demonstrate that the presence of wastewater bacteria was not necessary to improve algal productivity and settleability with algal recycling.

  16. Density-Gradient Determination of Osmotic Potential in Plant Cells

    ERIC Educational Resources Information Center

    Nabors, Murray W.

    1973-01-01

    Describes a method for measuring osmotic potential which is suitable for high school and college biology classes. This method introduces students to the hard-to-visualize technique of using density gradients to separate cells or cell constituents of differing densities. (JR)

  17. Enhanced performance of an air-cathode microbial fuel cell with oxygen supply from an externally connected algal bioreactor.

    PubMed

    Kakarla, Ramesh; Kim, Jung Rae; Jeon, Byong-Hun; Min, Booki

    2015-11-01

    An algae bioreactor (ABR) was externally connected to air-cathode microbial fuel cells (MFCs) to increase power generation by supplying a high amount of oxygen to cathode electrode. The MFC with oxygen fed from ABR produced maximum cell voltage and cathode potential at a fixed loading of 459 mV and 10 mV, respectively. During polarization analysis, the MFC displayed a maximum power density of 0.63 W/m(2) (at 2.06 A/m(2)) using 39.2% O2 from ABR, which was approximately 30% higher compared with use of atmospheric air (0.44 W/m(2), 20.8% O2,). The cyclic voltammogram analysis exhibited a higher reduction current of -137 mA with 46.5% O2 compared to atmospheric air (-115 mA). Oxygen supply by algae bioreactor to air-cathode MFC could also maintain better MFC performance in long term operation by minimizing cathode potential drop over time.

  18. Algal swimming velocities signal fatty acid accumulation.

    PubMed

    Hansen, Travis J; Hondzo, Miki; Mashek, Mara T; Mashek, Douglas G; Lefebvre, Paul A

    2013-01-01

    The use of microalgae for biofuel production will be beneficial to society if we can produce biofuels at large scales with minimal mechanical energy input in the production process. Understanding micro-algal physiological responses under variable environmental conditions in bioreactors is essential for the optimization of biofuel production. We demonstrate that measuring micro-algal swimming speed provides information on culture health and total fatty acid accumulation. Three strains of Chlamydomonas reinhardtii were grown heterotrophically on acetate and subjected to various levels of nitrogen starvation. Other nutrient levels were explored to determine their effect on micro-algal kinetics. Swimming velocities were measured with two-dimensional micro-particle tracking velocimetry. The results show an inverse linear relationship between normalized total fatty acid mass versus swimming speed of micro-algal cells. Analysis of RNA sequencing data confirms these results by demonstrating that the biological processes of cell motion and the generation of energy precursors are significantly down-regulated. Experiments demonstrate that changes in nutrient concentration in the surrounding media also affect swimming speed. The findings have the potential for the in situ and indirect assessment of lipid content by measuring micro-algal swimming kinetics.

  19. Method and system of culturing an algal mat

    DOEpatents

    Das, Keshav C; Cannon, Benjamin R; Bhatnagar, Ashish; Chinnasamy, Senthil

    2014-05-13

    A system and method for culturing algae are presented. The system and method utilize a fog of growth medium that is delivered to an algal mat generator along with a stream of CO.sub.2 to promote growth of algal cells contained in the generator.

  20. Excess seawater nutrients, enlarged algal symbiont densities and bleaching sensitive reef locations: 1. Identifying thresholds of concern for the Great Barrier Reef, Australia.

    PubMed

    Wooldridge, Scott A

    2016-05-23

    Here, I contribute new insight into why excess seawater nutrients are an increasingly identified feature at reef locations that have low resistance to thermal stress. Specifically, I link this unfavourable synergism to the development of enlarged (suboptimal) zooxanthellae densities that paradoxically limit the capacity of the host coral to build tissue energy reserves needed to combat periods of stress. I explain how both theoretical predictions and field observations support the existence of species-specific 'optimal' zooxanthellae densities ~1.0-3.0×10(6) cellscm-(2). For the central Great Barrier Reef (GBR), excess seawater nutrients that permit enlarged zooxanthellae densities beyond this optimum range are linked with seawater chlorophyll a>0.45μg·L(-1); a eutrophication threshold previously shown to correlate with a significant loss in species for hard corals and phototrophic octocorals on the central GBR, and herein shown to correlate with enhanced bleaching sensitivity during the 1998 and 2002 mass bleaching events.

  1. Uniform algal growth in photobioreactors using surface scatterers

    NASA Astrophysics Data System (ADS)

    Ahsan, Syed S.; Pereyra, Brandon; Erickson, David

    2014-03-01

    Cultures of algae, such as cyanobacteria, are a promising source of renewable energy. However, algal growth is highly dependent on light intensity and standard photobioreactors do a poor job of distributing light uniformly for algal utilization due to shading effects in dense algal cultures. Engineered scattering schemes are already employed in current slab-waveguide technologies, like edge-lit LEDs. Stacking such slab-waveguides that uniformly distribute light could potentially yield photobioreactors to overcome the shading effect and grow extremely high densities of algal cultures that would lower monetary and energetic costs. Here, we characterize and design a scattering scheme for specific application within photobioreactors which employs a gradient distribution of surface scatterers with uniform lateral scattering intensity. This uniform scattering scheme is shown to be superior for algal cultivation.

  2. Dynamic metabolic exchange governs a marine algal-bacterial interaction

    PubMed Central

    Segev, Einat; Wyche, Thomas P; Kim, Ki Hyun; Petersen, Jörn; Ellebrandt, Claire; Vlamakis, Hera; Barteneva, Natasha; Paulson, Joseph N; Chai, Liraz; Clardy, Jon; Kolter, Roberto

    2016-01-01

    Emiliania huxleyi is a model coccolithophore micro-alga that generates vast blooms in the ocean. Bacteria are not considered among the major factors influencing coccolithophore physiology. Here we show through a laboratory model system that the bacterium Phaeobacter inhibens, a well-studied member of the Roseobacter group, intimately interacts with E. huxleyi. While attached to the algal cell, bacteria initially promote algal growth but ultimately kill their algal host. Both algal growth enhancement and algal death are driven by the bacterially-produced phytohormone indole-3-acetic acid. Bacterial production of indole-3-acetic acid and attachment to algae are significantly increased by tryptophan, which is exuded from the algal cell. Algal death triggered by bacteria involves activation of pathways unique to oxidative stress response and programmed cell death. Our observations suggest that bacteria greatly influence the physiology and metabolism of E. huxleyi. Coccolithophore-bacteria interactions should be further studied in the environment to determine whether they impact micro-algal population dynamics on a global scale. DOI: http://dx.doi.org/10.7554/eLife.17473.001 PMID:27855786

  3. Water-quality parameters and benthic algal communities at selected streams in Minnesota, August 2000 - Study design, methods and data

    USGS Publications Warehouse

    Lee, K.E.

    2002-01-01

    This report describes the study design, sampling methods, and summarizes the physical, chemical, and benthic algal data for a component of the multiagency study that was designed to document diurnal water-quality measurements (specific conductance, pH, water temperature, and dissolved oxygen), benthic algal community composition and chlorophyll-a content, and primary productivity at 12 stream sites on 6 streams in Minnesota during August 2000. Specific conductance, pH, water temperature, dissolved oxygen concentrations and percent dissolved oxygen saturation measurements were made with submersible data recorders at 30 minute intervals for a period of 3-6 days during August 2000. Benthic algae collected from wood and rock substrate were identified and enumerated. Biovolume (volume of algal cells per unit area), density (number of cells per unit area), and chlorophyll-a content from benthic algae were determined. These data can be used as part of the multiagency study to develop an understanding of the relations among nutrient concentrations, algal abundance, algal community composition, and primary production and respiration processes in rivers of differing ecoregions in Minnesota.

  4. Aerotactic Cell Density Variations in Bacterial Turbulence

    NASA Astrophysics Data System (ADS)

    Fernandez, Vicente; Smriga, Steven; Menolascina, Filippo; Rusconi, Roberto; Stocker, Roman

    2015-11-01

    Concentrated suspensions of motile bacteria such as Bacillus subtilis exhibit group dynamics much larger than the scale of an individual bacterium, visual similar to high Reynolds number turbulence. These suspensions represent a microscale realization of active matter. Individually, B. subtilis are also aerotactic, and will accumulate near oxygen sources. Using a microfluidic device for generating oxygen gradients, we investigate the relationship between individuals' attraction to oxygen and the collective motion resultant from hydrodynamic interactions. We focus on changes in density revealed by a fluorescently labeled sub-population of B. subtilis in the dense suspension. This approach allows us to examine changes in density during the onset of collective motion as well as fully developed bacterial turbulence.

  5. Augmented mast cell infiltration and microvessel density in prostate cancer

    PubMed Central

    Wagrowska-Danilewicz, Małgorzata; Stasikowska-Kanicka, Olga; Tuka, Elżbieta; Danilewicz, Marian

    2013-01-01

    Aim of the study Recent investigations have taken into account the role of mast cells in prostate cancer formation, analyzing their dual functions (as tumour growth promoters and tumour growth inhibitors). The aim of our study was to compare mast cell infiltration and microvessel density in prostate cancer and in benign prostate hyperplasia. We also attempted to find possible relationships among mast cell infiltration and microvessel density, Gleason score, as well as serum levels of prostate-specific antigen (PSA). Material and methods The investigation was confined to evaluations of material from prostate needle biopsies, carried out in 26 patients with prostate cancer, and of 14 specimens diagnosed as benign hyperplasia. The numbers of tryptase positive mast cells and CD34 positive vessels were determined using a computer image analysis system. In the patients with prostate cancer, both mast cell infiltrates and microvessel density were significantly increased, as compared to the control patients. Results Significant positive correlations were identified between the mean numbers of mast cells and microvessel densities, both in the prostate cancer group and in the control group. Moreover, significant positive correlations were observed between Gleason score on one hand and the number of mast cells and microvessel density on the other. The correlations between PSA serum levels and both mast cell infiltration and microvessel density were positive, but not in a statistically significant way. Conclusions The reported investigations may support the assumption of mast cell promoter function in prostate cancer development, whereas no evidence was found for their opposite PMID:24592126

  6. Excess seawater nutrients, enlarged algal symbiont densities and bleaching sensitive reef locations: 2. A regional-scale predictive model for the Great Barrier Reef, Australia.

    PubMed

    Wooldridge, Scott A; Heron, Scott F; Brodie, Jon E; Done, Terence J; Masiri, Itsara; Hinrichs, Saskia

    2017-01-15

    A spatial risk assessment model is developed for the Great Barrier Reef (GBR, Australia) that helps identify reef locations at higher or lower risk of coral bleaching in summer heat-wave conditions. The model confirms the considerable benefit of discriminating nutrient-enriched areas that contain corals with enlarged (suboptimal) symbiont densities for the purpose of identifying bleaching-sensitive reef locations. The benefit of the new system-level understanding is showcased in terms of: (i) improving early-warning forecasts of summer bleaching risk, (ii) explaining historical bleaching patterns, (iii) testing the bleaching-resistant quality of the current marine protected area (MPA) network (iv) identifying routinely monitored coral health attributes, such as the tissue energy reserves and skeletal growth characteristics (viz. density and extension rates) that correlate with bleaching resistant reef locations, and (v) targeting region-specific water quality improvement strategies that may increase reef-scale coral health and bleaching resistance.

  7. Label-free density difference amplification-based cell sorting.

    PubMed

    Song, Jihwan; Song, Minsun; Kang, Taewook; Kim, Dongchoul; Lee, Luke P

    2014-11-01

    The selective cell separation is a critical step in fundamental life sciences, translational medicine, biotechnology, and energy harvesting. Conventional cell separation methods are fluorescent activated cell sorting and magnetic-activated cell sorting based on fluorescent probes and magnetic particles on cell surfaces. Label-free cell separation methods such as Raman-activated cell sorting, electro-physiologically activated cell sorting, dielectric-activated cell sorting, or inertial microfluidic cell sorting are, however, limited when separating cells of the same kind or cells with similar sizes and dielectric properties, as well as similar electrophysiological phenotypes. Here we report a label-free density difference amplification-based cell sorting (dDACS) without using any external optical, magnetic, electrical forces, or fluidic activations. The conceptual microfluidic design consists of an inlet, hydraulic jump cavity, and multiple outlets. Incoming particles experience gravity, buoyancy, and drag forces in the separation chamber. The height and distance that each particle can reach in the chamber are different and depend on its density, thus allowing for the separation of particles into multiple outlets. The separation behavior of the particles, based on the ratio of the channel heights of the inlet and chamber and Reynolds number has been systematically studied. Numerical simulation reveals that the difference between the heights of only lighter particles with densities close to that of water increases with increasing the ratio of the channel heights, while decreasing Reynolds number can amplify the difference in the heights between the particles considered irrespective of their densities.

  8. Distribution, behavior, and condition of herbivorous fishes on coral reefs track algal resources.

    PubMed

    Tootell, Jesse S; Steele, Mark A

    2016-05-01

    Herbivore distribution can impact community structure and ecosystem function. On coral reefs, herbivores are thought to play an important role in promoting coral dominance, but how they are distributed relative to algae is not well known. Here, we evaluated whether the distribution, behavior, and condition of herbivorous fishes correlated with algal resource availability at six sites in the back reef environment of Moorea, French Polynesia. Specifically, we tested the hypotheses that increased algal turf availability would coincide with (1) increased biomass, (2) altered foraging behavior, and (3) increased energy reserves of herbivorous fishes. Fish biomass and algal cover were visually estimated along underwater transects; behavior of herbivorous fishes was quantified by observations of focal individuals; fish were collected to assess their condition; and algal turf production rates were measured on standardized tiles. The best predictor of herbivorous fish biomass was algal turf production, with fish biomass increasing with algal production. Biomass of herbivorous fishes was also negatively related to sea urchin density, suggesting competition for limited resources. Regression models including both algal turf production and urchin density explained 94 % of the variation in herbivorous fish biomass among sites spread over ~20 km. Behavioral observations of the parrotfish Chlorurus sordidus revealed that foraging area increased as algal turf cover decreased. Additionally, energy reserves increased with algal turf production, but declined with herbivorous fish density, implying that algal turf is a limited resource for this species. Our findings support the hypothesis that herbivorous fishes can spatially track algal resources on coral reefs.

  9. Algal Biofuels Fact Sheet

    SciTech Connect

    2009-10-27

    This fact sheet provides information on algal biofuels, which are generating considerable interest around the world. They may represent a sustainable pathway for helping to meet the U.S. biofuel production targets set by the Energy Independence and Security Act of 2007.

  10. Harmful Algal Blooms Research

    EPA Science Inventory

    This project represents the Agency’s first effort to unify harmful algal blooms (HABs) research that had been previously carried out in isolation within various laboratories. A unified program is the most efficient way generate useful results for the Agency’s decision...

  11. Using live algae at the anode of a microbial fuel cell to generate electricity.

    PubMed

    Xu, Chang; Poon, Karen; Choi, Martin M F; Wang, Ruihua

    2015-10-01

    Live green microalgae Chlorella pyrenoidosa was introduced in the anode of a microbial fuel cell (MFC) to act as an electron donor. By controlling the oxygen content, light intensity, and algal cell density at the anode, microalgae would generate electricity without requiring externally added substrates. Two models of algal microbial fuel cells (MFCs) were constructed with graphite/carbon electrodes and no mediator. Model 1 algal MFC has live microalgae grown at the anode and potassium ferricyanide at the cathode, while model 2 algal MFC had live microalgae in both the anode and cathode in different growth conditions. Results indicated that a higher current produced in model 1 algal MFC was obtained at low light intensity of 2500 lx and algal cell density of 5 × 10(6) cells/ml, in which high algal density would limit the electricity generation, probably by increasing oxygen level and mass transfer problem. The maximum power density per unit anode volume obtained in model 1 algal MFC was relatively high at 6030 mW/m(2), while the maximum power density at 30.15 mW/m(2) was comparable with that of previous reported bacteria-driven MFC with graphite/carbon electrodes. A much smaller power density at 2.5 mW/m(2) was observed in model 2 algal MFC. Increasing the algal cell permeability by 4-nitroaniline would increase the open circuit voltage, while the mitochondrial acting and proton leak promoting agents resveratrol and 2,4-dinitrophenol would increase the electric current production in algal MFC.

  12. Constructing a High Density Cell Culture System

    NASA Technical Reports Server (NTRS)

    Spaulding, Glenn F. (Inventor)

    1996-01-01

    An annular culture vessel for growing mammalian cells is constructed in a one piece integral and annular configuration with an open end which is closed by an endcap. The culture vessel is rotatable about a horizontal axis by use of conventional roller systems commonly used in culture laboratories. The end wall of the endcap has tapered access ports to frictionally and sealingly receive the ends of hypodermic syringes. The syringes permit the introduction of fresh nutrient and withdrawal of spent nutrients. The walls are made of conventional polymeric cell culture material and are subjected to neutron bombardment to form minute gas permeable perforations in the walls.

  13. Fibroblast PER2 Circadian Rhythmicity Depends on Cell Density

    PubMed Central

    Noguchi, Takako; Wang, Lexie L.; Welsh, David K.

    2013-01-01

    Like neurons in the suprachiasmatic nucleus (SCN), the master circadian pacemaker in the brain, single fibroblasts can function as independent oscillators. In the SCN, synaptic and paracrine signaling among cells creates a robust, synchronized circadian oscillation, whereas there is no evidence for such integration in fibroblast cultures. However, interactions among single-cell fibroblast oscillators cannot be completely excluded, because fibroblasts were not isolated in previous work. In this study, we tested the autonomy of fibroblasts as single-cell circadian oscillators in high and low density culture, by single-cell imaging of cells from PER2::LUC circadian reporter mice. We found greatly reduced PER2::LUC rhythmicity in low density cultures, which could result from lack of either constitutive or rhythmic paracrine signals from neighboring fibroblasts. To discriminate between these two possibilities, we mixed PER2::LUC wild type (WT) cells with non-luminescent, non-rhythmic Bmal1−/− cells, so that density of rhythmic cells was low but overall cell density remained high. In this condition, WT cells showed clear rhythmicity similar to high density cultures. We also mixed PER2::LUC WT cells with non-luminescent, long period Cry2−/− cells. In this condition, WT cells showed a period no different from cells cultured with rhythmic WT cells or non-rhythmic Bmal1−/− cells. In previous work, we found that low K+ suppresses fibroblast rhythmicity, and we and others have found that either low K+ or low Ca2+ suppresses SCN rhythmicity. Therefore, we attempted to rescue rhythmicity of low density fibroblasts with high K+ (21 mM), high Ca2+ (3.6 mM), or conditioned medium. Conditioned medium from high density fibroblast cultures rescued rhythmicity of low density cultures, whereas high K+ or Ca2+ medium did not consistently rescue rhythmicity. These data suggest that fibroblasts require paracrine signals from adjacent cells for normal expression of rhythmicity

  14. Cell-free expression of the APP transmembrane fragments with Alzheimer's disease mutations using algal amino acid mixture for structural NMR studies.

    PubMed

    Bocharova, Olga V; Urban, Anatoly S; Nadezhdin, Kirill D; Bocharov, Eduard V; Arseniev, Alexander S

    2016-07-01

    Structural investigations need ready supply of the isotope labeled proteins with inserted mutations n the quantities sufficient for the heteronuclear NMR. Though cell-free expression system has been widely used in the past years, high startup cost and complex compound composition prevent many researches from the developing this technique, especially for membrane protein production. Here we demonstrate the utility of a robust, cost-optimized cell-free expression technique for production of the physiologically important transmembrane fragment of amyloid precursor protein, APP686-726, containing Alzheimer's disease mutations in the juxtamembrane (E693G, Arctic form) and the transmembrane parts (V717G, London form, or L723P, Australian form). The protein cost was optimized by varying the FM/RM ratio as well as the amino acid concentration. We obtained the wild-type and mutant transmembrane fragments in the pellet mode of continuous exchange cell-free system consuming only commercial algal mixture of the (13)C,(15)N-labeled amino acids. Scaling up analytical tests, we achieved milligram quantity yields of isotope labeled wild-type and mutant APP686-726 for structural studies by high resolution NMR spectroscopy in membrane mimicking environment. The described approach has from 5 to 23-fold cost advantage over the bacterial expression methods described earlier and 1.5 times exceeds our previous result obtained with the longer APP671-726WT fragment.

  15. High volumetric power density, non-enzymatic, glucose fuel cells.

    PubMed

    Oncescu, Vlad; Erickson, David

    2013-01-01

    The development of new implantable medical devices has been limited in the past by slow advances in lithium battery technology. Non-enzymatic glucose fuel cells are promising replacement candidates for lithium batteries because of good long-term stability and adequate power density. The devices developed to date however use an "oxygen depletion design" whereby the electrodes are stacked on top of each other leading to low volumetric power density and complicated fabrication protocols. Here we have developed a novel single-layer fuel cell with good performance (2 μW cm⁻²) and stability that can be integrated directly as a coating layer on large implantable devices, or stacked to obtain a high volumetric power density (over 16 μW cm⁻³). This represents the first demonstration of a low volume non-enzymatic fuel cell stack with high power density, greatly increasing the range of applications for non-enzymatic glucose fuel cells.

  16. Stability of high cell density brewery fermentations during serial repitching.

    PubMed

    Verbelen, Pieter J; Dekoninck, Tinne M L; Van Mulders, Sebastiaan E; Saerens, Sofie M G; Delvaux, Filip; Delvaux, Freddy R

    2009-11-01

    The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e. higher inoculum size). However, the decreased yeast net growth observed in these high cell density brewery fermentations can adversely affect the physiological stability throughout subsequent yeast generations. Therefore, different O(2) conditions (wort aeration and yeast preoxygenation) were applied to high cell density fermentation and eight generations of fermentations were evaluated together with conventional fermentations. Freshly propagated high cell density populations adapted faster to the fermentative conditions than normal cell density populations. Preoxygenating the yeast was essential for the yeast physiological and beer flavor compound stability of high cell density fermentations during serial repitching. In contrast, the use of non-preoxygenated yeast resulted in inadequate growth which caused (1) insufficient yield of biomass to repitch all eight generations, (2) a 10% decrease in viability, (3) a moderate increase of yeast age, (4) and a dramatic increase of the unwanted flavor compounds acetaldehyde and total diacetyl during the sequence of fermentations. Therefore, to achieve sustainable high cell density fermentations throughout the economical valuable process of serial repitching, adequate yeast growth is essential.

  17. Accelerating Commercialization of Algal Biofuels Through Partnerships (Brochure)

    SciTech Connect

    Not Available

    2011-10-01

    This brochure describes National Renewable Energy Laboratory's (NREL's) algal biofuels research capabilities and partnership opportunities. NREL is accelerating algal biofuels commercialization through: (1) Advances in applied biology; (2) Algal strain development; (3) Development of fuel conversion pathways; (4) Techno-economic analysis; and (5) Development of high-throughput lipid analysis methodologies. NREL scientists and engineers are addressing challenges across the algal biofuels value chain, including algal biology, cultivation, harvesting and extraction, and fuel conversion. Through partnerships, NREL can share knowledge and capabilities in the following areas: (1) Algal Biology - A fundamental understanding of algal biology is key to developing cost-effective algal biofuels processes. NREL scientists are experts in the isolation and characterization of microalgal species. They are identifying genes and pathways involved in biofuel production. In addition, they have developed a high-throughput, non-destructive technique for assessing lipid production in microalgae. (2) Cultivation - NREL researchers study algal growth capabilities and perform compositional analysis of algal biomass. Laboratory-scale photobioreactors and 1-m2 open raceway ponds in an on-site greenhouse allow for year-round cultivation of algae under a variety of conditions. A bioenergy-focused algal strain collection is being established at NREL, and our laboratory houses a cryopreservation system for long-term maintenance of algal cultures and preservation of intellectual property. (3) Harvesting and Extraction - NREL is investigating cost-effective harvesting and extraction methods suitable for a variety of species and conditions. Areas of expertise include cell wall analysis and deconstruction and identification and utilization of co-products. (4) Fuel Conversion - NREL's excellent capabilities and facilities for biochemical and thermochemical conversion of biomass to biofuels are being

  18. Composition for detection of cell density signal molecule

    DOEpatents

    Schwarz, Richard I.

    2001-01-01

    Disclosed herein is a novel proteinaceous cell density signal molecule (CDS), which is secreted by fibroblastic cells in culture, preferably tendon cells, and which provides a means by which the cells self-regulate their proliferation and the expression of differentiated function. CDS, and the antibodies which recognize them, are important for the development of diagnostics and treatments for injuries and diseases involving connective tissues, particularly tendon. Also disclosed are methods of production and use.

  19. Algal functional annotation tool

    SciTech Connect

    2012-07-12

    Abstract BACKGROUND: Progress in genome sequencing is proceeding at an exponential pace, and several new algal genomes are becoming available every year. One of the challenges facing the community is the association of protein sequences encoded in the genomes with biological function. While most genome assembly projects generate annotations for predicted protein sequences, they are usually limited and integrate functional terms from a limited number of databases. Another challenge is the use of annotations to interpret large lists of 'interesting' genes generated by genome-scale datasets. Previously, these gene lists had to be analyzed across several independent biological databases, often on a gene-by-gene basis. In contrast, several annotation databases, such as DAVID, integrate data from multiple functional databases and reveal underlying biological themes of large gene lists. While several such databases have been constructed for animals, none is currently available for the study of algae. Due to renewed interest in algae as potential sources of biofuels and the emergence of multiple algal genome sequences, a significant need has arisen for such a database to process the growing compendiums of algal genomic data. DESCRIPTION: The Algal Functional Annotation Tool is a web-based comprehensive analysis suite integrating annotation data from several pathway, ontology, and protein family databases. The current version provides annotation for the model alga Chlamydomonas reinhardtii, and in the future will include additional genomes. The site allows users to interpret large gene lists by identifying associated functional terms, and their enrichment. Additionally, expression data for several experimental conditions were compiled and analyzed to provide an expression-based enrichment search. A tool to search for functionally-related genes based on gene expression across these conditions is also provided. Other features include dynamic visualization of genes on KEGG

  20. Observations on gas exchange and element recycle within a gas-closed algal-mouse system

    NASA Technical Reports Server (NTRS)

    Smernoff, D. T.; Wharton, R. A., Jr.; Averner, M. M.

    1986-01-01

    Life support systems based on bioregeneration rely on the control and manipulation of organisms. Algae are potentially useful for a variety of Closed Ecological Life Support System (CELSS) functions including the revitalization of atmospheres, production of food and for nitrogen fixation. The results of experiments conducted with a gas-closed algal-mouse system designed to investigate gas exchange phenomena under varying algal environmental conditions, and the ability of algae to utilize oxidized mouse solid waste are reported. Inherent instabilities exist between the uptake and release of carbon dioxide (CO2) and oxygen (O2) by the mouse and algae in a gas-closed system. Variations in light intensity and cell density alter the photosynthetic rate of the algae and enable short-term steady-state concentrations of atmospheric CO2 and O2. Different nitrogen sources (urea and nitrate) result in different algal assimilatory quotients (AQ). Combinations of photosynthetic rate and AQ ratio manipulations were examined for their potential in stabilizing atmospheric gas concentrations in the gas-closed algal-mouse system.

  1. Engineering high-density endothelial cell monolayers on soft substrates.

    PubMed

    Feinberg, Adam W; Schumacher, James F; Brennan, Anthony B

    2009-07-01

    This study demonstrates that a confluent monolayer of endothelial cells (ECs) can be tissue engineered on a soft substrate with a cell density and morphology that approximates in vivo conditions. We achieved formation of a confluent EC monolayer on polydimethylsiloxane (PDMS) elastomer by microcontact printing of fibronectin (FN) in a square lattice array of 3microm diameter circular islands at a 6microm pitch. Uniform coatings of FN or serum proteins on PDMS or on tissue-culture-treated polystyrene failed to support the equivalent EC density and/or confluence. The ECs on the FN micropatterned PDMS achieved a density of 1,536+/-247cellsmm(-2), close to the 3,215+/-336cellsmm(-2) observed in vivo from porcine pulmonary artery and significantly higher (2- to 5-fold) than EC density on other materials. The probable mechanism for enhanced EC adhesion, growth and density is increased focal adhesion (FA) formation between the ECs and the substrate. After 14days culture, the micropatterned FN surface increased the average number of FAs per cell to 35+/-10, compared to 7+/-6 for ECs on PDMS uniformly coated with FN. Thus, microscale patterning of FN into FA-sized, circular islands on PDMS elastomer promotes the formation of EC monolayers with in vivo-like cell density and morphology.

  2. The Origin and Evolution of the Plant Cell Surface: Algal Integrin-Associated Proteins and a New Family of Integrin-Like Cytoskeleton-ECM Linker Proteins

    PubMed Central

    Becker, Burkhard; Doan, Jean Michel; Wustman, Brandon; Carpenter, Eric J.; Chen, Li; Zhang, Yong; Wong, Gane K.-S.; Melkonian, Michael

    2015-01-01

    The extracellular matrix of scaly green flagellates consists of small organic scales consisting of polysaccharides and scale-associated proteins (SAPs). Molecular phylogenies have shown that these organisms represent the ancestral stock of flagellates from which all green plants (Viridiplantae) evolved. The molecular characterization of four different SAPs is presented. Three SAPs are type-2 membrane proteins with an arginine/alanine-rich short cytoplasmic tail and an extracellular domain that is most likely of bacterial origin. The fourth protein is a filamin-like protein. In addition, we report the presence of proteins similar to the integrin-associated proteins α-actinin (in transcriptomes of glaucophytes and some viridiplants), LIM-domain proteins, and integrin-associated kinase in transcriptomes of viridiplants, glaucophytes, and rhodophytes. We propose that the membrane proteins identified are the predicted linkers between scales and the cytoskeleton. These proteins are present in many green algae but are apparently absent from embryophytes. These proteins represent a new protein family we have termed gralins for green algal integrins. Gralins are absent from embryophytes. A model for the evolution of the cell surface proteins in Plantae is discussed. PMID:25977459

  3. National Algal Biofuels Technology Roadmap

    SciTech Connect

    Ferrell, John; Sarisky-Reed, Valerie

    2010-05-01

    The framework for National Algal Biofuels Technology Roadmap was constructed at the Algal Biofuels Technology Roadmap Workshop, held December 9-10, 2008, at the University of Maryland-College Park. The Workshop was organized by the Biomass Program to discuss and identify the critical challenges currently hindering the development of a domestic, commercial-scale algal biofuels industry. This Roadmap presents information from a scientific, economic, and policy perspectives that can support and guide RD&D investment in algal biofuels. While addressing the potential economic and environmental benefits of using algal biomass for the production of liquid transportation fuels, the Roadmap describes the current status of algae RD&D. In doing so, it lays the groundwork for identifying challenges that likely need to be overcome for algal biomass to be used in the production of economically viable biofuels.

  4. Anorexia Reduces GFAP+ Cell Density in the Rat Hippocampus

    PubMed Central

    Labrada-Moncada, Francisco Emmanuel; Varman, Durairaj Ragu; Krüger, Janina; Morales, Teresa; Miledi, Ricardo; Martínez-Torres, Ataúlfo

    2016-01-01

    Anorexia nervosa is an eating disorder observed primarily in young women. The neurobiology of the disorder is unknown but recently magnetic resonance imaging showed a volume reduction of the hippocampus in anorexic patients. Dehydration-induced anorexia (DIA) is a murine model that mimics core features of this disorder, including severe weight loss due to voluntary reduction in food intake. The energy supply to the brain is mediated by astrocytes, but whether their density is compromised by anorexia is unknown. Thus, the aim of this study was to estimate GFAP+ cell density in the main regions of the hippocampus (CA1, CA2, CA3, and dentate gyrus) in the DIA model. Our results showed that GFAP+ cell density was significantly reduced (~20%) in all regions of the hippocampus, except in CA1. Interestingly, DIA significantly reduced the GFAP+ cells/nuclei ratio in CA2 (−23%) and dentate gyrus (−48%). The reduction of GFAP+ cell density was in agreement with a lower expression of GFAP protein. Additionally, anorexia increased the expression of the intermediate filaments vimentin and nestin. Accordingly, anorexia increased the number of reactive astrocytes in CA2 and dentate gyrus more than twofold. We conclude that anorexia reduces the hippocampal GFAP+ cell density and increases vimentin and nestin expression. PMID:27579183

  5. Density dependent polarized secretion of a prostatic epithelial cell line.

    PubMed

    Djakiew, D; Pflug, B; Delsite, R; Lynch, J H; Onoda, M

    1992-01-01

    The polarized secretions (apical/basal) of newly synthesized total protein and proteases from prostatic epithelial sheets of PA-III cells grown in dual compartment chambers were investigated at various cell densities and culture conditions. PA-III cells grown in a serum free defined medium (SFDM) form morphologically polarized monolayers of epithelial cells. These cells secreted their 35S-methionine labeled total protein in a predominantly apical direction (apical/basal ratio, 4-8 fold), with a lesser proportion of protein secreted apically at lower cell densities of the PA-III cell monolayer. PA-III cells grown in 5% fetal calf serum (FCS) are morphologically squamous, comparable to the anaplastic phenotype, and exhibited an inversion of polarized total protein secretion (apical/basal ratio, 0.4-0.9 fold), with an increased proportion of total protein secreted in a basal direction at lower cell densities. Since the culture of PA-III cells in FCS may approximate the anaplastic phenotype we investigated the polarized secretion of proteases from these cells at various cell densities, and compared them with the secretory pattern of protease secretion from polarized PA-III cells cultured in SFDM. At lower cell densities of the PA-III cells grown in FCS the polarity of protease secretion was inverted such that metalloproteinases, tissue type plasminogen activator, and a 72 kD gelatinase were secreted in a predominantly basal direction, as well as urokinase and a gelatinase of 26 kD that were secreted more or less equally into the apical and basal compartments of the chambers. On the other hand, for cultures of PA-III cells grown in SFDM the aforementioned proteases exhibited predominantly an apically directed polarity of secretion. These results suggest that the anaplastic phenotype characterized by a loss of polarized structure may also be characterized by a functional loss or inversion of polarized secretion. The consequences of such a loss or inversion of polarized

  6. Energetic potential of algal biomass from high-rate algal ponds for the production of solid biofuels.

    PubMed

    Costa, Taynan de Oliveira; Calijuri, Maria Lúcia; Avelar, Nayara Vilela; Carneiro, Angélica de Cássia de Oliveira; de Assis, Letícia Rodrigues

    2016-10-17

    In this investigation, chemical characteristics, higher, lower and net heating value, bulk and energy density, and thermogravimetric analysis were applied to study the thermal characteristics of three algal biomasses. These biomasses, grown as by-products of wastewater treatment in high-rate algal ponds (HRAPs), were: (i) biomass produced in domestic effluent and collected directly from an HRAP (PO); (ii) biomass produced in domestic effluent in a mixed pond-panel system and collected from the panels (PA); and (iii) biomass originating from the treatment effluent from the meat processing industry and collected directly from an HRAP (IN). The biomass IN was the best alternative for thermal power generation. Subsequently, a mixture of the algal biomasses and Jatropha epicarp was used to produce briquettes containing 0%, 25%, 50%, 75%, and 100% of algal biomass, and their properties were evaluated. In general, the addition of algal biomass to briquettes decreased both the hygroscopicity and fixed carbon content and increased the bulk density, ash content, and energy density. A 50% proportion of biomass IN was found to be the best raw material for producing briquettes. Therefore, the production of briquettes consisting of algal biomass and Jatropha epicarp at a laboratory scale was shown to be technically feasible.

  7. Density gradient electrophoresis of cultured human embryonic kidney cells

    NASA Technical Reports Server (NTRS)

    Plank, L. D.; Kunze, M. E.; Giranda, V.; Todd, P. W.

    1985-01-01

    Ground based confirmation of the electrophoretic heterogeneity of human embryonic kidney cell cultures, the general characterization of their electrophoretic migration, and observations on the general properties of cultures derived from electrophoretic subpopulations were studied. Cell migration in a density gradient electrophoresis column and cell electrophoretic mobility was determined. The mobility and heterogeneity of cultured human embryonic kidney cells with those of fixed rat erythrocytes as model test particle was compared. Electrophoretically separated cell subpopulations with respect to size, viability, and culture characteristics were examined.

  8. Oxidized low-density lipoprotein induces hematopoietic stem cell senescence.

    PubMed

    Zhang, Xian-Ping; Zhang, Gui-Hai; Wang, Yu-Ying; Liu, Jun; Wei, Qiang; Xu, Chun-Yan; Wang, Jian-Wei; Wang, Ya-Ping

    2013-09-01

    We have investigated oxidized low-density lipoprotein (ox-LDL) induced senescence in hematopoietic stem cells (HCs). Mouse Sca-1+ HCs were separated and purified using the magnetic activated cell sorting technique. Ox-LDL induced significant senescence in HCs measured by SA-β-Gal staining, and reduced CFU-Mix colony-forming capacity, arresting cells at G0/G1 phase. In agreement with the cell cycle arrest, ox-LDL markedly reduced the expression of CDK4, cyclin D, and cyclin E. As possible contributing factors for cell senescence, ox-LDL also induced cellular oxidative stress and reduced telomerase activity.

  9. Advanced Algal Systems Fact Sheet

    SciTech Connect

    2016-06-01

    Research and development (R&D) on advanced algal biofuels and bioproducts presents an opportunity to sustainably expand biomass resource potential in the United States. The Bioenergy Technologies Office’s (BETO’s) Advanced Algal Systems Program is carrying out a long-term, applied R&D strategy to lower the costs of algal biofuel production by working with partners to develop revolutionary technologies and conduct crosscutting analyses to better understand the potential

  10. Enhancement of algal growth and productivity by grazing zooplankton.

    PubMed

    Porter, K G

    1976-06-25

    Colonies of the common planktonic green alga, Sphaerocystis schroeteri, are only partially disrupted and assimilated by Daphnia magna, a natural predator. The Daphnia break up the outer protective gelatinous sheath that surrounds Sphaerocystis colonies, but most of the algal cells emerge from Daphnia guts intact and in viable condition. During gut passage, these viable cells take up nutrients, such as phosphorus, both from algal remains and from Daphnia metabolites. This nutrient supply stimulates algal carbon fixation and cell division. Enhanced algal growth, observed after gut passage, can compensate for the minor losses to the population caused by grazing. Nutrients regenerated by grazers may produce the summer bloom of gelatinous green algae during the seasonal succession of lake phytoplankton.

  11. Recent Advances in Algal Genetic Tool Development

    DOE PAGES

    R. Dahlin, Lukas; T. Guarnieri, Michael

    2016-06-24

    The goal of achieving cost-effective biofuels and bioproducts derived from algal biomass will require improvements along the entire value chain, including identification of robust, high-productivity strains and development of advanced genetic tools. Though there have been modest advances in development of genetic systems for the model alga Chlamydomonas reinhardtii, progress in development of algal genetic tools, especially as applied to non-model algae, has generally lagged behind that of more commonly utilized laboratory and industrial microbes. This is in part due to the complex organellar structure of algae, including robust cell walls and intricate compartmentalization of target loci, as well asmore » prevalent gene silencing mechanisms, which hinder facile utilization of conventional genetic engineering tools and methodologies. However, recent progress in global tool development has opened the door for implementation of strain-engineering strategies in industrially-relevant algal strains. Here, we review recent advances in algal genetic tool development and applications in eukaryotic microalgae.« less

  12. Density-Dependent Metabolic Heterogeneity in Human Mesenchymal Stem Cells

    PubMed Central

    Liu, Yijun; Munoz, Nathalie; Bunnell, Bruce A.; Logan, Timothy M.; Ma, Teng

    2016-01-01

    Human mesenchymal stem cells (hMSCs) are intrinsically heterogeneous and comprise subpopulations that differ in their proliferation, multi-potency, and functional properties, which are commonly demonstrated by culturing hMSCs at different plating densities. The objective of this study was to investigate the metabolic profiles of different subpopulations of hMSC by testing the hypothesis that the clonogenic hMSC subpopulation, which is selectively enriched in clonal density (CD) and low density (LD) culture (10 and 100 cells per square centimeter, respectively), possesses a metabolic phenotype that differs from that of hMSC in medium- or high-density (MD: 1,000 and HD: 3,000 cells per square centimeter, respectively). Cells at CD and LD conditions exhibited elevated expression of CD146 and colony forming unit-fibroblast compared with cells at MD- or HD. Global metabolic profiles revealed by gas chromatography-mass spectrometry of cell extracts showed clear distinction between LD and HD cultures, and density-dependent differences in coupling of glycolysis to the TCA cycle. Metabolic inhibitors revealed density-dependent differences in glycolysis versus oxidative phosphorylation (OXPHOS) for ATP generation, in glutamine metabolism, in the dependence on the pentose phosphate pathway for maintaining cellular redox state, and sensitivity to exogenous reactive oxygen species. We also show that active OXPHOS is not required for proliferation in LD culture but that OXPHOS activity increases senescence in HD culture. Together, the results revealed heterogeneity in hMSC culture exists at the level of primary metabolism. The unique metabolic characteristics of the clonogenic subpopulation suggest a novel approach for optimizing in vitro expansion of hMSCs. PMID:26274841

  13. Algal biofuels from wastewater treatment high rate algal ponds.

    PubMed

    Craggs, R J; Heubeck, S; Lundquist, T J; Benemann, J R

    2011-01-01

    This paper examines the potential of algae biofuel production in conjunction with wastewater treatment. Current technology for algal wastewater treatment uses facultative ponds, however, these ponds have low productivity (∼10 tonnes/ha.y), are not amenable to cultivating single algal species, require chemical flocculation or other expensive processes for algal harvest, and do not provide consistent nutrient removal. Shallow, paddlewheel-mixed high rate algal ponds (HRAPs) have much higher productivities (∼30 tonnes/ha.y) and promote bioflocculation settling which may provide low-cost algal harvest. Moreover, HRAP algae are carbon-limited and daytime addition of CO(2) has, under suitable climatic conditions, the potential to double production (to ∼60 tonnes/ha.y), improve bioflocculation algal harvest, and enhance wastewater nutrient removal. Algae biofuels (e.g. biogas, ethanol, biodiesel and crude bio-oil), could be produced from the algae harvested from wastewater HRAPs, The wastewater treatment function would cover the capital and operation costs of algal production, with biofuel and recovered nutrient fertilizer being by-products. Greenhouse gas abatement results from both the production of the biofuels and the savings in energy consumption compared to electromechanical treatment processes. However, to achieve these benefits, further research is required, particularly the large-scale demonstration of wastewater treatment HRAP algal production and harvest.

  14. High Energy Density Regenerative Fuel Cell Systems for Terrestrial Applications

    NASA Technical Reports Server (NTRS)

    Burke, Kenneth A.

    1999-01-01

    Regenerative Fuel Cell System (RFCS) technology for energy storage has been a NASA power system concept for many years. Compared to battery-based energy storage systems, RFCS has received relatively little attention or resources for development because the energy density and electrical efficiency were not sufficiently attractive relative to advanced battery systems. Even today, RFCS remains at a very low technology readiness level (TRL of about 2 indicating feasibility has been demonstrated). Commercial development of the Proton Exchange Membrane (PEM) fuel cells for automobiles and other terrestrial applications and improvements in lightweight pressure vessel design to reduce weight and improve performance make possible a high energy density RFCS energy storage system. The results from this study of a lightweight RFCS energy storage system for a remotely piloted, solar-powered, high altitude aircraft indicate an energy density up to 790 w-h/kg with electrical efficiency of 53.4% is attainable. Such an energy storage system would allow a solar-powered aircraft to carry hundreds of kilograms of payload and remain in flight indefinitely for use in atmospheric research, earth observation, resource mapping. and telecommunications. Future developments in the areas of hydrogen and oxygen storage, pressure vessel design, higher temperature and higher- pressure fuel cell operation, unitized regenerative fuel cells, and commercial development of fuel cell technology will improve both the energy density and electrical efficiency of the RFCS.

  15. Detection and quantification of subtle changes in red blood cell density using a cell phone.

    PubMed

    Felton, Edward J; Velasquez, Anthony; Lu, Shulin; Murphy, Ryann O; ElKhal, Abdala; Mazor, Ofer; Gorelik, Pavel; Sharda, Anish; Ghiran, Ionita C

    2016-08-16

    Magnetic levitation has emerged as a technique that offers the ability to differentiate between cells with different densities. We have developed a magnetic levitation system for this purpose that distinguishes not only different cell types but also density differences in cells of the same type. This small-scale system suspends cells in a paramagnetic medium in a capillary placed between two rare earth magnets, and cells levitate to an equilibrium position determined solely by their density. Uniform reference beads of known density are used in conjunction with the cells as a means to quantify their levitation positions. In one implementation images of the levitating cells are acquired with a microscope, but here we also introduce a cell phone-based device that integrates the magnets, capillary, and a lens into a compact and portable unit that acquires images with the phone's camera. To demonstrate the effectiveness of magnetic levitation in cell density analysis we carried out levitation experiments using red blood cells with artificially altered densities, and also levitated those from donors. We observed that we can distinguish red blood cells of an anemic donor from those that are healthy. Since a plethora of disease states are characterized by changes in cell density magnetic cell levitation promises to be an effective tool in identifying and analyzing pathologic states. Furthermore, the low cost, portability, and ease of use of the cell phone-based system may potentially lead to its deployment in low-resource environments.

  16. Substrate Compliance versus Ligand Density in Cell on Gel Responses

    PubMed Central

    Engler, Adam; Bacakova, Lucie; Newman, Cynthia; Hategan, Alina; Griffin, Maureen; Discher, Dennis

    2004-01-01

    Substrate stiffness is emerging as an important physical factor in the response of many cell types. In agreement with findings on other anchorage-dependent cell lineages, aortic smooth muscle cells are found to spread and organize their cytoskeleton and focal adhesions much more so on “rigid” glass or “stiff” gels than on “soft” gels. Whereas these cells generally show maximal spreading on intermediate collagen densities, the limited spreading on soft gels is surprisingly insensitive to adhesive ligand density. Bell-shaped cell spreading curves encompassing all substrates are modeled by simple functions that couple ligand density to substrate stiffness. Although smooth muscle cells spread minimally on soft gels regardless of collagen, GFP-actin gives a slight overexpression of total actin that can override the soft gel response and drive spreading; GFP and GFP-paxillin do not have the same effect. The GFP-actin cells invariably show an organized filamentous cytoskeleton and clearly indicate that the cytoskeleton is at least one structural node in a signaling network that can override spreading limits typically dictated by soft gels. Based on such results, we hypothesize a central structural role for the cytoskeleton in driving the membrane outward during spreading whereas adhesion reinforces the spreading. PMID:14695306

  17. Enhanced power production from microbial fuel cells with high cell density culture.

    PubMed

    Zhai, Dan-Dan; Li, Bing; Sun, Jian-Zhong; Sun, De-Zhen; Si, Rong-Wei; Yong, Yang-Chun

    2016-01-01

    Improvement of power production in a microbial fuel cell (MFC) with a high cell density culture strategy was developed. By using high cell density culture, the voltage output and power density output of the MFC were enhanced about 0.6 and 1.6 times compared to the control, respectively. Further analysis showed that riboflavin concentration in the MFC was dramatically increased from 0.1 mg/L to 1.2 mg/L by high cell density culture. Moreover, the biofilm formation on the anode surface was significantly enhanced by this new strategy. The increased accumulation of electron shuttle (riboflavin) as well as enhanced biofilm formation contributed to the improvement in anodic electrochemical activity and these factors were the underlying mechanism for MFC performance improvement by high cell density culture. This work demonstrated that high cell density culture would be a simple and practical strategy for MFC manipulation.

  18. Antigen Density Dictates Immune Responsiveness following Red Blood Cell Transfusion.

    PubMed

    Arthur, Connie M; Patel, Seema R; Smith, Nicole H; Bennett, Ashley; Kamili, Nourine A; Mener, Amanda; Gerner-Smidt, Christian; Sullivan, Harold C; Hale, J Scott; Wieland, Andreas; Youngblood, Benjamin; Zimring, James C; Hendrickson, Jeanne E; Stowell, Sean R

    2017-04-01

    Although RBC transfusion can result in the development of anti-RBC alloantibodies that increase the probability of life-threatening hemolytic transfusion reactions, not all patients generate anti-RBC alloantibodies. However, the factors that regulate immune responsiveness to RBC transfusion remain incompletely understood. One variable that may influence alloantibody formation is RBC alloantigen density. RBC alloantigens exist at different densities on the RBC surface and likewise exhibit distinct propensities to induce RBC alloantibody formation. However, although distinct alloantigens reside on the RBC surface at different levels, most alloantigens also represent completely different structures, making it difficult to separate the potential impact of differences in Ag density from other alloantigen features that may also influence RBC alloimmunization. To address this, we generated RBCs that stably express the same Ag at different levels. Although exposure to RBCs with higher Ag levels induces a robust Ab response, RBCs bearing low Ag levels fail to induce RBC alloantibodies. However, exposure to low Ag-density RBCs is not without consequence, because recipients subsequently develop Ag-specific tolerance. Low Ag-density RBC-induced tolerance protects higher Ag-density RBCs from immune-mediated clearance, is Ag specific, and occurs through the induction of B cell unresponsiveness. These results demonstrate that Ag density can potently impact immune outcomes following RBC transfusion and suggest that RBCs with altered Ag levels may provide a unique tool to induce Ag-specific tolerance.

  19. High volumetric power density, non-enzymatic, glucose fuel cells

    PubMed Central

    Oncescu, Vlad; Erickson, David

    2013-01-01

    The development of new implantable medical devices has been limited in the past by slow advances in lithium battery technology. Non-enzymatic glucose fuel cells are promising replacement candidates for lithium batteries because of good long-term stability and adequate power density. The devices developed to date however use an “oxygen depletion design” whereby the electrodes are stacked on top of each other leading to low volumetric power density and complicated fabrication protocols. Here we have developed a novel single-layer fuel cell with good performance (2 μW cm−2) and stability that can be integrated directly as a coating layer on large implantable devices, or stacked to obtain a high volumetric power density (over 16 μW cm−3). This represents the first demonstration of a low volume non-enzymatic fuel cell stack with high power density, greatly increasing the range of applications for non-enzymatic glucose fuel cells. PMID:23390576

  20. Recycling algae to improve species control and harvest efficiency from a high rate algal pond.

    PubMed

    Park, J B K; Craggs, R J; Shilton, A N

    2011-12-15

    This paper investigates the influence of recycling gravity harvested algae on species dominance and harvest efficiency in wastewater treatment High Rate Algal Ponds (HRAP). Two identical pilot-scale HRAPs were operated over one year either with (HRAP(r)) or without (HRAP(c)) harvested algal biomass recycling. Algae were harvested from the HRAP effluent in algal settling cones (ASCs) and harvest efficiency was compared to settlability in Imhoff cones five times a week. A microscopic image analysis technique was developed to determine relative algal dominance based on biovolume and was conducted once a month. Recycling of harvested algal biomass back to the HRAP(r) maintained the dominance of a single readily settleable algal species (Pediastrum sp.) at >90% over one year (compared to the control with only 53%). Increased dominance of Pediastrum sp. greatly improved the efficiency of algal harvest (annual average of >85% harvest for the HRAP(r) compared with ∼60% for the control). Imhoff cone experiments demonstrated that algal settleability was influenced by both the dominance of Pediastrum sp. and the species composition of remaining algae. Algal biomass recycling increased the average size of Pediastrum sp. colonies by 13-30% by increasing mean cell residence time. These results indicate that recycling gravity harvested algae could be a simple and effective operational strategy to maintain the dominance of readily settleable algal species, and enhance algal harvest by gravity sedimentation.

  1. Time analysis of corneal endothelial cell density after cataract extraction.

    PubMed

    Galin, M A; Lin, L L; Fetherolf, E; Obstbaum, S A; Sugar, A

    1979-07-01

    Serial endothelial photographs were taken preoperatively and postoperatively in 200 eyes; 111 eyes contained a Rayner iris clip lens, 54 eyes contained a Fyodorov Sputnik lens, and 35 eyes had no lens. Central endothelial cell density was changed in all instances, with counts in implanted eyes declining 25 to 30%, and in nonimplanted eyes 10 to 15%. In both instances, the decline essentially ceased at about three months. The cause of the greater decline in implanted eyes appeared to be mechanical and subsequent cell loss after the 90-day period was virtually equal for the two groups. Methods that may be used to alter the difference in cell density occurring with implantation are best analyzed by using the 90-day period data for comparison.

  2. Effect of cell density on adipogenic differentiation of mesenchymal stem cells.

    PubMed

    Lu, Hongxu; Guo, Likun; Wozniak, Michal J; Kawazoe, Naoki; Tateishi, Tetsuya; Zhang, Xingdong; Chen, Guoping

    2009-04-10

    The effect of cell density on the adipogenic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs) was investigated by using a patterning technique to induce the formation of a cell density gradient on a micropatterned surface. The adipogenic differentiation of MSCs at a density gradient from 5 x 10(3) to 3 x 10(4) cells/cm2 was examined. Lipid vacuoles were observed at all cell densities after 1-3 weeks of culture in adipogenic differentiation medium although the lipid vacuoles were scarce at the low cell density and abundant at the high cell density. Real-time RT-PCR analysis showed that adipogenesis marker genes encoding peroxisome proliferator-activated receptor gamma2 (PPARgamma2), lipoprotein lipase (LPL), and fatty acid binding protein-4 (FABP4) were detected in the MSCs cultured at all cell densities. The results suggest that there was no apparent effect of cell density on the adipogenic differentiation of human MSCs.

  3. Effect of cell density on adipogenic differentiation of mesenchymal stem cells

    SciTech Connect

    Lu, Hongxu; Guo, Likun; Wozniak, Michal J.; Kawazoe, Naoki; Tateishi, Tetsuya; Zhang, Xingdong; Chen, Guoping

    2009-04-10

    The effect of cell density on the adipogenic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs) was investigated by using a patterning technique to induce the formation of a cell density gradient on a micropatterned surface. The adipogenic differentiation of MSCs at a density gradient from 5 x 10{sup 3} to 3 x 10{sup 4} cells/cm{sup 2} was examined. Lipid vacuoles were observed at all cell densities after 1-3 weeks of culture in adipogenic differentiation medium although the lipid vacuoles were scarce at the low cell density and abundant at the high cell density. Real-time RT-PCR analysis showed that adipogenesis marker genes encoding peroxisome proliferator-activated receptor {gamma}2 (PPAR{gamma}2), lipoprotein lipase (LPL), and fatty acid binding protein-4 (FABP4) were detected in the MSCs cultured at all cell densities. The results suggest that there was no apparent effect of cell density on the adipogenic differentiation of human MSCs.

  4. Low-density-lipoprotein receptors in different rabbit liver cells.

    PubMed Central

    Nenseter, M S; Myklebost, O; Blomhoff, R; Drevon, C A; Nilsson, A; Norum, K R; Berg, T

    1989-01-01

    Receptor-dependent uptake mechanisms for low-density lipoprotein (LDL) were studied in rabbit liver parenchymal and non-parenchymal cells. Hybridization studies with a cDNA probe revealed that mRNA for the apo (apolipoprotein) B,E receptor was present in endothelial and Kupffer cells as well as in parenchymal cells. By ligand-blotting experiments we showed that apo B,E-receptor protein was present in both parenchymal and non-parenchymal cells. Studies of binding of homologous LDL in cultured rabbit parenchymal cells suggested that about 63% of the specific LDL binding was mediated via the apo B,E receptor. Approx. 47% of the specific LDL binding was dependent on Ca2+, suggesting that specific Ca2+-dependent as well as Ca2+-independent LDL-binding sites exist in liver parenchymal cells. Methylated LDL bound to the parenchymal cells in a saturable manner. Taken together, our results showed that apo B,E receptors are present in rabbit liver endothelial and Kupffer cells as well as in the parenchymal cells, and that an additional saturable binding activity for LDL may exist on rabbit liver parenchymal cells. This binding activity was not inhibited by EGTA or reductive methylation of lysine residues in apo B. LDL degradation in parenchymal cells was mainly mediated via the apo B,E receptor. Images Fig. 1. Fig. 2. PMID:2549976

  5. Collection and conversion of algal lipid

    NASA Astrophysics Data System (ADS)

    Lin, Ching-Chieh

    Sustainable economic activities mandate a significant replacement of fossil energy by renewable forms. Algae-derived biofuels are increasingly seen as an alternative source of energy with potential to supplement the world's ever increasing demand. Our primary objective is, once the algae were cultivated, to eliminate or make more efficient energy-intensive processing steps of collection, drying, grinding, and solvent extraction prior to conversion. To overcome the processing barrier, we propose to streamline from cultivated algae to biodiesel via algal biomass collection by sand filtration, cell rupturing with ozone, and immediate transesterification. To collect the algal biomass, the specific Chlorococcum aquaticum suspension was acidified to pH 3.3 to promote agglomeration prior to sand filtration. The algae-loaded filter bed was drained of free water and added with methanol and ozonated for 2 min to rupture cell membrane to accelerate release of the cellular contents. The methanol solution now containing the dissolved lipid product was collected by draining, while the filter bed was regenerated by further ozonation when needed. The results showed 95% collection of the algal biomass from the suspension and a 16% yield of lipid from the algae, as well as restoration of filtration velocity of the sand bed via ozonation. The results further showed increased lipid yield upon cell rupturing and transesterified products composed entirely of fatty acid methyl ester (FAME) compounds, demonstrating that the rupture and transesterification processes could proceed consecutively in the same medium, requiring no separate steps of drying, extraction, and conversion. The FAME products from algae without exposure to ozone were mainly of 16 to 18 carbons containing up to 3 double bonds, while those from algae having been ozonated were smaller, highly saturated hydrocarbons. The new technique streamlines individual steps from cultivated algal lipid to transesterified products and

  6. Nanostructured thin solid oxide fuel cells with high power density.

    PubMed

    Ignatiev, Alex; Chen, Xin; Wu, Naijuan; Lu, Zigui; Smith, Laverne

    2008-10-28

    Nanostructured thin film solid oxide fuel cells (SOFC) have been developed for reduced temperature operation, with high power density, and to be self reforming. A thin film electrolyte (1-2 microm thickness), e.g., yttria-stabilized zirconia (YSZ), is deposited on a nickel foil substrate. The electrolyte thin film is polycrystalline when deposited on a polycrystalline nickel foil substrate, and is (100) textured when deposited on an atomically textured nickel foil substrate. The Ni foil substrate is then converted into a porous SOFC anode by photolithographic patterning and etching to develop porosity. A composite La(0.5)Sr(0.5)CoO(3) cathode is then deposited on the thin film electrolyte. The resultant thin film hetero structure fuel cells have operated at a significantly reduced temperature: as low as 470 degrees C, with a maximum power density of 140 mW cm(-2) at 575 degrees C, and an efficiency of >50%. This drastic reduction in operating temperature for an SOFC now also allows for the use of hydrocarbon fuels without the need for a separate reformer as the nickel anode effectively dissociates hydrocarbons within this temperature range. These nanostructured fuel cells show excellent potential for high power density, small volume, high efficiency fuel cells for power generation applications.

  7. Improving photosynthesis for algal biofuels: toward a green revolution.

    PubMed

    Stephenson, Patrick G; Moore, C Mark; Terry, Matthew J; Zubkov, Mikhail V; Bibby, Thomas S

    2011-12-01

    Biofuels derived from marine algae are a potential source of sustainable energy that can contribute to future global demands. The realisation of this potential will require manipulation of the fundamental biology of algal physiology to increase the efficiency with which solar energy is ultimately converted into usable biomass. This 'photosynthetic solar energy conversion efficiency' sets an upper limit on the potential of algal-derived biofuels. In this review, we outline photosynthetic molecular targets that could be manipulated to increase the efficiency and yield of algal biofuel production. We also highlight modern 'omic' and high-throughput technologies that might enable identification, selection and improvement of algal cell lines on timescales relevant for achieving significant contributions to future energy solutions.

  8. The photonic density of states and the light energy density in cholesteric liquid crystal cells

    NASA Astrophysics Data System (ADS)

    Gevorgyan, A. H.; Oganesyan, K. B.; Karapetyan, R. V.; Rafayelyan, M. S.

    2013-12-01

    The photonic density of states (PDS) of the eigen polarizations (EPs) in cholesteric liquid crystal (CLC) cells are calculated. The dependences of the PDS on the parameters characterizing absorption, gain and refractive index of the CLC layer surroundings were obtained. We investigated the possibility of connections between the PDS and the density of the light energy accumulated in the medium and showed that these characteristics have analogous spectra and, besides, the influences of the problem parameters on these characteristics also are analogous. It was shown that the decrement of the refractive index of the CLC layer surroundings leads to a sharp increase of the maximum PDS and, consequently, leads to a sharp decrement of the laser excitation threshold. We showed that the subject system can work as a low threshold laser or a multi-position trigger.

  9. Algal Biofuels; Algal Biofuels R&D at NREL (Brochure)

    SciTech Connect

    Not Available

    2010-09-01

    An overview of NREL's algal biofuels projects, including U.S. Department of Energy-funded work, projects with U.S. and international partners, and Laboratory Directed Research and Development projects.

  10. Impact of Cell Density on Differentiation Efficiency of Rat Adipose-derived Stem Cells into Schwann-like Cells

    PubMed Central

    Najafabadi, Mahtab Maghzi; Bayati, Vahid; Orazizadeh, Mahmoud; Hashemitabar, Mahmoud; Absalan, Forouzan

    2016-01-01

    Background and Objectives Schwann-like (SC-like) cells induced from adipose-derived stem cells (ASCs) may be one of the ideal alternative cell sources for obtaining Schwann cells (SCs). They can be used for treating peripheral nerve injuries. Co-culture with SCs or exposure to glial growth factors are commonly used for differentiation of ASCs to SC-like cells. However, the effect of initial cell density as an inductive factor on the differentiation potential of ASCs into the SC-like cells has not been yet investigated. Methods and Results ASCs were harvested from rat and characterized. The cells were seeded into the culture flasks at three different initial cell densities i.e. 2×103, 4×103 and 8×103 cells/cm2 an overnight and differentiated toward SC-like cells using glial growth factors. After two weeks, the differentiation rate of ASCs to SC-like cells at different densities was assessed by immunofluorescence, fluorescence-activated cell sorting analysis and real time RT-PCR. Expression of the typical SCs markers, S-100 proteins and glial fibrillary acidic protein (GFAP) protein, was observed in all cell densities groups although the number of S100-positive and GFAP-positive cells, and the expression of p75NTR mRNA, another SC marker, were significantly higher at the density of 8×103 cells/cm2 when compared with the other cell densities groups (p<0.001). Conclusions The results suggest that the higher differentiation rate of ASCs to SC-like cells can be obtained at initial cell density of 8×103 cells/cm2, possibly via increased cell-cell interaction and cell density-dependent influence of glial growth factors. PMID:27788569

  11. Algal sludge from Taihu Lake can be utilized to create novel PGPR-containing bio-organic fertilizers.

    PubMed

    Zhang, Miao; Li, Rong; Cao, Liangliang; Shi, Juanjuan; Liu, Hongjun; Huang, Yan; Shen, Qirong

    2014-01-01

    Large amounts of refloated algal sludge from Taihu Lake result in secondary environmental pollution due to annual refloatation. This study investigated the possibility to produce bio-organic fertilizer (BIO) using algal sludge as a solid-state fermentation (SSF) medium. Results showed that addition of algal sludge contributed to efficient SFF by a plant growth-promoting rhizobacteria (PGPR) strain SQR9 and improved the nutrient contents in the novel BIO. The optimum water content and initial inoculation size were 45% and 5%, respectively. After 6 days of SSF, the biomass of strain SQR9 was increased to a cell density of more than 5 × 10(7) CFU g(-1). Microcystins were rapidly degraded, and a high germination index value was observed. Plant growth experiments showed that the produced BIO efficiently promoted plant growth. Additional testing showed that the novel SSF process was also suitable for other PGPR strains. This study provides a novel way of high-value utilization of algal sludge from Taihu Lake by producing low-cost but high-quality BIOs.

  12. Cortical cell and neuron density estimates in one chimpanzee hemisphere.

    PubMed

    Collins, Christine E; Turner, Emily C; Sawyer, Eva Kille; Reed, Jamie L; Young, Nicole A; Flaherty, David K; Kaas, Jon H

    2016-01-19

    The density of cells and neurons in the neocortex of many mammals varies across cortical areas and regions. This variability is, perhaps, most pronounced in primates. Nonuniformity in the composition of cortex suggests regions of the cortex have different specializations. Specifically, regions with densely packed neurons contain smaller neurons that are activated by relatively few inputs, thereby preserving information, whereas regions that are less densely packed have larger neurons that have more integrative functions. Here we present the numbers of cells and neurons for 742 discrete locations across the neocortex in a chimpanzee. Using isotropic fractionation and flow fractionation methods for cell and neuron counts, we estimate that neocortex of one hemisphere contains 9.5 billion cells and 3.7 billion neurons. Primary visual cortex occupies 35 cm(2) of surface, 10% of the total, and contains 737 million densely packed neurons, 20% of the total neurons contained within the hemisphere. Other areas of high neuron packing include secondary visual areas, somatosensory cortex, and prefrontal granular cortex. Areas of low levels of neuron packing density include motor and premotor cortex. These values reflect those obtained from more limited samples of cortex in humans and other primates.

  13. High-density lipoprotein exerts vasculoprotection via endothelial progenitor cells

    PubMed Central

    Petoumenos, Vasileios; Nickenig, Georg; Werner, Nikos

    2009-01-01

    Endothelial progenitor cells (EPC) enhance endothelial cell repair, improve endothelial dysfunction and are a predictor for cardiovascular mortality. High-density lipoprotein (HDL) cholesterol levels inversely correlate with cardiovascular events and have vasculoprotective effects. Here we postulate that HDL influences EPC biology. HDL and EPC were isolated according to standard procedures. Differentiation of mononuclear cells into DiLDL/lectin positive cells was enhanced after HDL treatment compared to vehicle. HDL was able to inhibit apoptosis (TUNEL assay, annexin V staining) while proliferation (BrdU incorporation) of early outgrowth colonies after extended cell cultivation (14 days) was increased. Flow chamber experiments revealed an improved adhesion of HDL pre-incubated EPC on human coronary artery endothelial cells (HCAEC) compared to vehicle while HDL treatment of HCAEC prevented adhesion of inflammatory cells. Flow cytometry demonstrated an up-regulation of β2- and α4-integrins on HDL pre-incubated EPC. Blocking experiments revealed a unique role of β2-integrin in EPC adhesion. Treatment of wild-type mice with recombinant HDL after endothelial denudation resulted in enhanced re-endothelialization compared to vehicle. Finally, in patients with coronary artery disease a correlation between circulating EPC and HDL concentrations was demonstrated. We provide evidence that HDL mediates important vasculoprotective action via the improvement of function of circulating EPC. PMID:18705697

  14. Very High Density of CHO Cells in Perfusion by ATF or TFF in WAVE Bioreactor™. Part I. Effect of the Cell Density on the Process

    PubMed Central

    Clincke, Marie-Françoise; Mölleryd, Carin; Zhang, Ye; Lindskog, Eva; Walsh, Kieron; Chotteau, Véronique

    2013-01-01

    High cell density perfusion process of antibody producing CHO cells was developed in disposable WAVE Bioreactor™ using external hollow fiber filter as cell separation device. Both “classical” tangential flow filtration (TFF) and alternating tangential flow system (ATF) equipment were used and compared. Consistency of both TFF- and ATF-based cultures was shown at 20–35 × 106 cells/mL density stabilized by cell bleeds. To minimize the nutrients deprivation and by-product accumulation, a perfusion rate correlated to the cell density was applied. The cells were maintained by cell bleeds at density 0.9–1.3 × 108 cells/mL in growing state and at high viability for more than 2 weeks. Finally, with the present settings, maximal cell densities of 2.14 × 108 cells/mL, achieved for the first time in a wave-induced bioreactor, and 1.32 × 108 cells/mL were reached using TFF and ATF systems, respectively. Using TFF, the cell density was limited by the membrane capacity for the encountered high viscosity and by the pCO2 level. Using ATF, the cell density was limited by the vacuum capacity failing to pull the highly viscous fluid. Thus, the TFF system allowed reaching higher cell densities. The TFF inlet pressure was highly correlated to the viscosity leading to the development of a model of this pressure, which is a useful tool for hollow fiber design of TFF and ATF. At very high cell density, the viscosity introduced physical limitations. This led us to recommend cell densities under 1.46 × 108 cell/mL based on the analysis of the theoretical distance between the cells for the present cell line. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:754–767, 2013 PMID:23436789

  15. Very high density of CHO cells in perfusion by ATF or TFF in WAVE bioreactor™. Part I. Effect of the cell density on the process.

    PubMed

    Clincke, Marie-Françoise; Mölleryd, Carin; Zhang, Ye; Lindskog, Eva; Walsh, Kieron; Chotteau, Véronique

    2013-01-01

    High cell density perfusion process of antibody producing CHO cells was developed in disposable WAVE Bioreactor™ using external hollow fiber filter as cell separation device. Both "classical" tangential flow filtration (TFF) and alternating tangential flow system (ATF) equipment were used and compared. Consistency of both TFF- and ATF-based cultures was shown at 20-35 × 10(6) cells/mL density stabilized by cell bleeds. To minimize the nutrients deprivation and by-product accumulation, a perfusion rate correlated to the cell density was applied. The cells were maintained by cell bleeds at density 0.9-1.3 × 10(8) cells/mL in growing state and at high viability for more than 2 weeks. Finally, with the present settings, maximal cell densities of 2.14 × 10(8) cells/mL, achieved for the first time in a wave-induced bioreactor, and 1.32 × 10(8) cells/mL were reached using TFF and ATF systems, respectively. Using TFF, the cell density was limited by the membrane capacity for the encountered high viscosity and by the pCO2 level. Using ATF, the cell density was limited by the vacuum capacity failing to pull the highly viscous fluid. Thus, the TFF system allowed reaching higher cell densities. The TFF inlet pressure was highly correlated to the viscosity leading to the development of a model of this pressure, which is a useful tool for hollow fiber design of TFF and ATF. At very high cell density, the viscosity introduced physical limitations. This led us to recommend cell densities under 1.46 × 10(8) cell/mL based on the analysis of the theoretical distance between the cells for the present cell line.

  16. High cell density cultivation of the chemolithoautotrophic bacterium Nitrosomonas europaea.

    PubMed

    Papp, Benedek; Török, Tibor; Sándor, Erzsébet; Fekete, Erzsébet; Flipphi, Michel; Karaffa, Levente

    2016-05-01

    Nitrosomonas europaea is a chemolithoautotrophic nitrifier, a gram-negative bacterium that can obtain all energy required for growth from the oxidation of ammonia to nitrite, and this may be beneficial for various biotechnological and environmental applications. However, compared to other bacteria, growth of ammonia oxidizing bacteria is very slow. A prerequisite to produce high cell density N. europaea cultures is to minimize the concentrations of inhibitory metabolic by-products. During growth on ammonia nitrite accumulates, as a consequence, N. europaea cannot grow to high cell concentrations under conventional batch conditions. Here, we show that single-vessel dialysis membrane bioreactors can be used to obtain substantially increased N. europaea biomasses and substantially reduced nitrite levels in media initially containing high amounts of the substrate. Dialysis membrane bioreactor fermentations were run in batch as well as in continuous mode. Growth was monitored with cell concentration determinations, by assessing dry cell mass and by monitoring ammonium consumption as well as nitrite formation. In addition, metabolic activity was probed with in vivo acridine orange staining. Under continuous substrate feed, the maximal cell concentration (2.79 × 10(12)/L) and maximal dry cell mass (0.895 g/L) achieved more than doubled the highest values reported for N. europaea cultivations to date.

  17. Defect density and dielectric constant in perovskite solar cells

    SciTech Connect

    Samiee, Mehran; Konduri, Siva; Abbas, Hisham A.; Joshi, Pranav; Zhang, Liang; Dalal, Vikram; Ganapathy, Balaji; Kottokkaran, Ranjith; Noack, Max; Kitahara, Andrew

    2014-10-13

    We report on measurement of dielectric constant, mid-gap defect density, Urbach energy of tail states in CH{sub 3}NH{sub 3}PbI{sub x}Cl{sub 1−x} perovskite solar cells. Midgap defect densities were estimated by measuring capacitance vs. frequency at different temperatures and show two peaks, one at 0.66 eV below the conduction band and one at 0.24 eV below the conduction band. The attempt to escape frequency is in the range of 2 × 10{sup 11}/s. Quantum efficiency data indicate a bandgap of 1.58 eV. Urbach energies of valence and conduction band are estimated to be ∼16 and ∼18 meV. Measurement of saturation capacitance indicates that the relative dielectric constant is ∼18.

  18. [Usage of flocculation in emergent control of algal bloom in drinking water supplying reservoir].

    PubMed

    Xiao, Li-juan; Han, Bo-ping; Lin, Qiu-qi; Lei, La-mei

    2007-10-01

    An Anabaena circinalis bloom appeared in a reservoir for supplying drinking water in the south of China, in April 2006. Phytoplankton scums gathered and floated on the surface of the whole reservoir especially on the area of water intake, and the cell density of phytoplankton, cyanobacteria and Anabaena circinalis was as high as 7.3 x 10(7), 7.2 x 10(7), 4.1 x 10(7) cells x L(-1) respectively. To maintain drinking water supplying, an emergency program was initiated to control the cyanobacterial bloom. The zone immediately adjacent to the water intake was divided into two small zones by fishing nets and waterproof curtains to modify the water flow. Iron-based flocculants were then applied to control the algal bloom. As a result, the density of the phytoplankton decreased greatly, and at the first day the cell densities of phytoplankton, cyanobacterial, Anabaena circinalis decreased to 5.3 x 10(6), 4.7 x 10(6), 2 x 10(6) cells x L(-1) respectively, and the removal of them reached up to 93%, 94%, 95% respectively. The average of phytoplankton cell density was 1.2 x 10(7) cells x L(-1) and a highest density was 2.0 x 10(7) cells x L(-1) during the treatment from 22 to 30 April, while Chlorophyta and Bacillariophyta slightly increased. These encouraging results suggest that the flocculants used are efficient at removing Cyanobacteria.

  19. Mechanical algal disruption for efficient biodiesel extraction

    NASA Astrophysics Data System (ADS)

    Krehbiel, Joel David

    Biodiesel from algae provides several benefits over current biodiesel feedstocks, but the energy requirements of processing algae into a useable fuel are currently so high as to be prohibitive. One route to improving this is via disruption of the cells prior to lipid extraction, which can significantly increase energy recovery. Unfortunately, several obvious disruption techniques require more energy than can be gained. This dissertation examines the use of microbubbles to improve mechanical disruption of algal cells using experimental, theoretical, and computational methods. New laboratory experiments show that effective ultrasonic disruption of algae is achieved by adding microbubbles to an algal solution. The configuration studied flows the solution through a tube and insonifies a small section with a high-pressure ultrasound wave. Previous biomedical research has shown effective cell membrane damage on animal cells with similar methods, but the present research is the first to extend such study to algal cells. Results indicate that disruption increases with peak negative pressure between 1.90 and 3.07 MPa and with microbubble concentration up to 12.5 x 107 bubbles/ml. Energy estimates of this process suggest that it requires only one-fourth the currently most-efficient laboratory-scale disruption process. Estimates of the radius near each bubble that causes disruption (i.e. the disruption radius) suggest that it increases with peak negative pressure and is near 9--20 microm for all cases tested. It is anticipated that these procedures can be designed for better efficiency and efficacy, which will be facilitated by identifying the root mechanisms of the bubble-induced disruption. We therefore examine whether bubble expansion alone creates sufficient cell deformation for cell rupture. The spherically-symmetric Marmottant model for bubble dynamics allows estimation of the flow regime under experimental conditions. Bubble expansion is modeled as a point source of

  20. Oxidized low-density lipoprotein alters endothelial progenitor cell populations.

    PubMed

    Cui, Yuqi; Narasimhulu, Chandrakala A; Liu, Lingjuan; Li, Xin; Xiao, Yuan; Zhang, Jia; Xie, Xiaoyun; Hao, Hong; Liu, Jason Z; He, Guanglong; Cowan, Peter J; Cui, Lianqun; Zhu, Hua; Parthasarathy, Sampath; Liu, Zhenguo

    2015-06-01

    Oxidized low-density lipoprotein (ox-LDL) is critical to atherosclerosis in hyperlipidemia. Bone marrow (BM)-derived endothelial progenitor cells (EPCs) are important to preventing atherosclerosis, and significantly decreased in hyperlipidemia. This study was to demonstrate ox-LDL and hyperlipidemia could exhibit similar effect on EPC population and the role of reactive oxygen species (ROS). ROS production in BM and blood was significantly increased in male C57BL/6 mice with intravenous ox-LDL treatment, and in hyperlipidemic LDL receptor knockout mice with 4-month high-fat diet. ROS formation was effectively blocked with overexpression of antioxidant enzymes or N-acetylcysteine treatment. In hyperlipidemic and ox-LDL-treated mice, c-Kit(+)/CD31(+) cell number in BM and blood, and Sca-1(+)/Flk-1(+) cell number in blood, not in BM, were significantly decreased, which were not affected by inhibiting ROS production, while blood CD34(+)/Flk-1(+) cell number was significantly increased that was prevented with reduced ROS formation. However, blood CD34(+)/CD133(+) cell number increased in ox-LDL-treated mice, while decreased in hyperlipidemic mice. These data suggested that ox-LDL produced significant changes in BM and blood EPC populations similar (but not identical) to chronic hyperlipidemia with predominantly ROS-independent mechanism(s).

  1. Theoretical analysis of cell separation based on cell surface marker density.

    PubMed

    Chalmers, J J; Zborowski, M; Moore, L; Mandal, S; Fang, B B; Sun, L

    1998-07-05

    A theoretical analysis was performed to determine the number of fractions a multidisperse, immunomagnetically labeled cell population can be separated into based on the surface marker (antigen) density. A number of assumptions were made in this analysis: that there is a proportionality between the number of surface markers on the cell surface and the number of immunomagnetic labels bound; that this surface marker density is independent of the cell diameter; and that there is only the presence of magnetic and drag forces acting on the cell. Due to the normal distribution of cell diameters, a "randomizing" effect enters into the analysis, and an analogy between the "theoretical plate" analysis of distillation, adsorption, and chromatography can be made. Using the experimentally determined, normal distribution of cell diameters for human lymphocytes and a breast cancer cell line, and fluorescent activated cell screening data of specific surface marker distributions, examples of theoretical plate calculations were made and discussed.

  2. Fluid flow plate for decreased density of fuel cell assembly

    DOEpatents

    Vitale, Nicholas G.

    1999-01-01

    A fluid flow plate includes first and second outward faces. Each of the outward faces has a flow channel thereon for carrying respective fluid. At least one of the fluids serves as reactant fluid for a fuel cell of a fuel cell assembly. One or more pockets are formed between the first and second outward faces for decreasing density of the fluid flow plate. A given flow channel can include one or more end sections and an intermediate section. An interposed member can be positioned between the outward faces at an interface between an intermediate section, of one of the outward faces, and an end section, of that outward face. The interposed member can serve to isolate the reactant fluid from the opposing outward face. The intermediate section(s) of flow channel(s) on an outward face are preferably formed as a folded expanse.

  3. The Effects of Physicochemical Factors and Cell Density on Nitrite Transformation in a Lipid-Rich Chlorella.

    PubMed

    Liang, Fang; Du, Kui; Wen, Xiaobin; Luo, Liming; Geng, Yahong; Li, Yeguang

    2015-12-28

    To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO3 concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m(2); temperature: 30°C; pH: 7-8; NaHCO3 concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R(2) = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NOX.

  4. High power density proton exchange membrane fuel cells

    NASA Technical Reports Server (NTRS)

    Murphy, Oliver J.; Hitchens, G. Duncan; Manko, David J.

    1993-01-01

    Proton exchange membrane (PEM) fuel cells use a perfluorosulfonic acid solid polymer film as an electrolyte which simplifies water and electrolyte management. Their thin electrolyte layers give efficient systems of low weight, and their materials of construction show extremely long laboratory lifetimes. Their high reliability and their suitability for use in a microgravity environment makes them particularly attractive as a substitute for batteries in satellites utilizing high-power, high energy-density electrochemical energy storage systems. In this investigation, the Dow experimental PEM (XUS-13204.10) and unsupported high platinum loading electrodes yielded very high power densities, of the order of 2.5 W cm(exp -2). A platinum black loading of 5 mg per cm(exp 2) was found to be optimum. On extending the three-dimensional reaction zone of fuel cell electrodes by impregnating solid polymer electrolyte into the electrode structures, Nafion was found to give better performance than the Dow experimental PEM. The depth of penetration of the solid polymer electrolyte into electrode structures was 50-70 percent of the thickness of the platinum-catalyzed active layer. However, the degree of platinum utilization was only 16.6 percent and the roughness factor of a typical electrode was 274.

  5. F-cell levels are altered with erythrocyte density in sickle cell disease.

    PubMed

    Basu, Sumanta; Dash, Bisnu Prasad; Patel, Dilip Kumar; Chakravarty, Sudipa; Chakravarty, Amit; Banerjee, Debashis; Chakrabarti, Abhijit

    2011-08-15

    Lighter cells from density fractionated erythrocytes of sickle cell disease (SCD) patients carry higher amount of externalized phosphatidylserine (PS) and cell surface glycophorins compared to the denser counterparts. Further analysis also revealed that the denser cells contained higher levels of fetal hemoglobin (HbF) compared to the lighter cells, supported by the presence of larger number of F-cells in these populations. In this report, we have found direct evidence on the higher survival of the HbF rich erythrocytes in SCD.

  6. Cell-density dependent effects of low-dose ionizing radiation on E. coli cells.

    PubMed

    Alipov, E D; Shcheglov, V S; Sarimov, R M; Belyaev, I Ya

    2003-01-01

    The changes in genome conformational state (GCS) induced by low-dose ionizing radiation in E. coli cells were measured by the method of anomalous viscosity time dependence (AVTD) in cellular lysates. Effects of X-rays at doses 0.1 cGy--1 Gy depended on post-irradiation time. Significant relaxation of DNA loops followed by a decrease in AVTD. The time of maximum relaxation was between 5-80 min depending on the dose of irradiation. U-shaped dose response was observed with increase of AVTD in the range of 0.1-4 Gy and decrease in AVTD at higher doses. No such increase in AVTD was seen upon irradiation of cells at the beginning of cell lysis while the AVTD decrease was the same. Significant differences in the effects of X-rays and gamma-rays at the same doses were observed suggesting a strong dependence of low-dose effects on LET. Effects of 0.01 cGy gamma-rays were studied at different cell densities during irradiation. We show that the radiation-induced changes in GCS lasted longer at higher cell density as compared to lower cell density. Only small amount of cells were hit at this dose and the data suggest cell-to-cell communication in response to low-dose ionizing radiation. This prolonged effect was also observed when cells were irradiated at high cell density and diluted to low cell density immediately after irradiation. These data suggest that cell-to-cell communication occur during irradiation or within 3 min post-irradiation. The cell-density dependent response to low-dose ionizing radiation was compared with previously reported data on exposure of E. coli cells to electromagnetic fields of extremely low frequency and extremely high frequency (millimeter waves). The body of our data show that cells can communicate in response to electromagnetic fields and ionizing radiation, presumably by reemission of secondary photons in infrared-submillimeter frequency range.

  7. Sapphire Energy - Integrated Algal Biorefinery

    SciTech Connect

    White, Rebecca L.; Tyler, Mike

    2015-07-22

    Sapphire Energy, Inc. (SEI) is a leader in large-scale photosynthetic algal biomass production, with a strongly cohesive research, development, and operations program. SEI takes a multidiscipline approach to integrate lab-based strain selection, cultivation and harvest and production scale, and extraction for the production of Green Crude oil, a drop in replacement for traditional crude oil.. SEI’s technical accomplishments since 2007 have produced a multifunctional platform that can address needs for fuel, feed, and other higher value products. Figure 1 outlines SEI’s commercialization process, including Green Crude production and refinement to drop in fuel replacements. The large scale algal biomass production facility, the SEI Integrated Algal Biorefinery (IABR), was built in Luna County near Columbus, New Mexico (see fig 2). The extraction unit was located at the existing SEI facility in Las Cruces, New Mexico, approximately 95 miles from the IABR. The IABR facility was constructed on time and on budget, and the extraction unit expansion to accommodate the biomass output from the IABR was completed in October 2012. The IABR facility uses open pond cultivation with a proprietary harvesting method to produce algal biomass; this biomass is then shipped to the extraction facility for conversion to Green Crude. The operation of the IABR and the extraction facilities has demonstrated the critical integration of traditional agricultural techniques with algae cultivation knowledge for algal biomass production, and the successful conversion of the biomass to Green Crude. All primary unit operations are de-risked, and at a scale suitable for process demonstration. The results are stable, reliable, and long-term cultivation of strains for year round algal biomass production. From June 2012 to November 2014, the IABR and extraction facilities produced 524 metric tons (MT) of biomass (on a dry weight basis), and 2,587 gallons of Green Crude. Additionally, the IABR

  8. Algal taxonomy forum: Algal Taxonomist, Let Serendipity Reign!

    PubMed

    Druehl, Louis

    2013-04-01

    The publication of a mini-review by Olivier De Clerck et al. in this issue of the Journal of Phycology presented an opportunity to open a dialogue on challenges faced by contemporary algal taxonomists. The Editorial Office solicited the following two additional contributions in response to De Clerck et al.'s paper; the responses were edited solely for clarity, space and format.

  9. Scan-Free Absorbance Spectral Imaging A(x, y, λ) of Single Live Algal Cells for Quantifying Absorbance of Cell Suspensions.

    PubMed

    Isono, Takumi; Yamashita, Kyohei; Momose, Daisuke; Kobayashi, Hiroki; Kitamura, Masashi; Nishiyama, Yusuke; Hosoya, Takahiro; Kanda, Hiroaki; Kudo, Ayane; Okada, Norihide; Yagi, Takafumi; Nakata, Kazuaki; Mineki, Shigeru; Tokunaga, Eiji

    2015-01-01

    Label-free, non-invasive, rapid absorbance spectral imaging A(x,y,λ) microscopy of single live cells at 1.2 μm × 1.2 μm resolution with an NA = 0.85 objective was developed and applied to unicellular green algae Chlamydomonas reinhardtii. By introducing the fiber assembly to rearrange a two-dimensional image to the one-dimensional array to fit the slit of an imaging spectrograph equipped with a CCD detector, scan-free acquisition of three-dimensional information of A(x,y,λ) was realized. The space-resolved absorbance spectra of the eyespot, an orange organelle about 1 μm, were extracted from the green-color background in a chlorophyll-rich single live cell absorbance image. Characteristic absorbance change in the cell suspension after hydrogen photoproduction in C. reinhardtii was investigated to find a single 715-nm absorption peak was locally distributed within single cells. The formula to calculate the absorbance of cell suspensions from that of single cells was presented to obtain a quantitative, parameter-free agreement with the experiment. It is quantitatively shown that the average number of chlorophylls per cell is significantly underestimated when it is evaluated from the absorbance of the cell suspensions due to the package effect.

  10. Algal Energy Conversion and Capture

    NASA Astrophysics Data System (ADS)

    Hazendonk, P.

    2015-12-01

    We address the potential for energy conversions and capture for: energy generation; reduction in energy use; reduction in greenhouse gas emissions; remediation of water and air pollution; protection and enhancement of soil fertility. These processes have the potential to sequester carbon at scales that may have global impact. Energy conversion and capture strategies evaluate energy use and production from agriculture, urban areas and industries, and apply existing and emerging technologies to reduce and recapture energy embedded in waste products. The basis of biocrude production from Micro-algal feedstocks: 1) The nutrients from the liquid fraction of waste streams are concentrated and fed into photo bioreactors (essentially large vessels in which microalgae are grown) along with CO2 from flue gasses from down stream processes. 2) The algae are processed to remove high value products such as proteins and beta-carotenes. The advantage of algae feedstocks is the high biomass productivity is 30-50 times that of land based crops and the remaining biomass contains minimal components that are difficult to convert to biocrude. 3) The remaining biomass undergoes hydrothermal liquefaction to produces biocrude and biochar. The flue gasses of this process can be used to produce electricity (fuel cell) and subsequently fed back into the photobioreactor. The thermal energy required for this process is small, hence readily obtained from solar-thermal sources, and furthermore no drying or preprocessing is required keeping the energy overhead extremely small. 4) The biocrude can be upgraded and refined as conventional crude oil, creating a range of liquid fuels. In principle this process can be applied on the farm scale to the municipal scale. Overall, our primary food production is too dependent on fossil fuels. Energy conversion and capture can make food production sustainable.

  11. Isolation of high density lipoproteins from rat intestinal epithelial cells.

    PubMed Central

    Magun, A M; Brasitus, T A; Glickman, R M

    1985-01-01

    Previous studies have defined forms of high density lipoproteins (HDL) in rat mesenteric lymph, suggesting that they have a secretory origin. This study describes the isolation and characterization of intestinal intracellular HDL. Two preparations were made as follows: (a) Rat enterocytes were isolated and a Golgi organelle fraction was prepared. (b) Cell homogenates were subjected to nitrogen cavitation and a cytoplasmic fraction was prepared. Lipoproteins were isolated from both preparations by sequential ultracentrifugation. When the HDL fraction (1.07-1.21 g/ml) was subjected to isopyknic density gradient ultracentrifugation, a peak of apoproteins A-I and B (apoA-I and apoB, respectively) was found at a density of 1.11-1.14 g/ml. Electron microscopy of the fraction showed spherical particles ranging in size from 6 to 13 nm. Immunoelectrophoresis revealed a precipitin arc in the alpha region against apoA-I which extended into the pre-beta region where a precipitin arc against apoB was also seen. ApoB antisera depleted the pre-beta particles whereas the alpha migrating particles remained. Lipid analysis of the whole HDL fraction revealed phospholipid, cholesteryl ester, and triglyceride as the major lipids. [3H]leucine was then administered into the duodenum and a radiolabeled intracellular HDL fraction was isolated. The newly synthesized apoproteins of the HDL fraction, as determined by gel electrophoresis, were apoB, apoA-I, and apolipoprotein A-IV (ApoA-IV). Immunoprecipitation of the apoB particles revealed apoA-I and apoA-IV in the supernatant. These data demonstrate that there are at least two intracellular intestinal forms of HDL particles, one of which contains apoB. The other particle contains apoA-I and apoA-IV, has alpha mobility, is spherical, and resembles a particle found in the lymph. Images PMID:3965504

  12. Low density of sympathetic nerve fibres and increased density of brain derived neurotrophic factor positive cells in RA synovium

    PubMed Central

    Weidler, C; Holzer, C; Harbuz, M; Hofbauer, R; Angele, P; Scholmerich, J; Straub, R

    2005-01-01

    Objective: To investigate the correlation between density of nerve fibres and the presence of BDNF+ cells. Methods: Densities of nerve fibres and BDNF+ cells were detected by quantitative immunohistochemistry in fresh synovial tissue from 52 patients with RA, 59 with OA, and 26 controls (Co). BDNF was also detected by in situ hybridisation. Results: Sympathetic nerve fibre density was similar in Co and OA but markedly reduced in RA (p = 0.002), whereas density of substance P positive (SP+) sensory nerve fibres was lower in OA than in Co and RA (p = 0.002). The ratio of sympathetic/SP+ sensory nerve fibre density was highest in OA and Co, followed by RA. The correlation between density of sympathetic nerve fibres and SP+ sensory nerve fibres in OA (R = 0.425, p = 0.001) was strongly positive, had a positive trend in Co (R = 0.243, NS), but was negative in RA (R = –0.292, p = 0.040). In RA and OA tissue the density of BDNF+ cells was high in sublining areas but markedly lower in Co (p = 0.001). BDNF+ cell density correlated positively with the ratio of sympathetic/SP+ sensory nerve fibre density in Co (R = 0.433, p = 0.045) and in OA (R = 0.613, p = 0.015), but not in RA (R = 0.101, NS). Immunohistochemical double staining demonstrated that some macrophages and fibroblasts were positive for BDNF. Conclusions: The correlation of density of SP+ sensory with sympathetic nerve fibres was positive in Co and OA but negative in RA. BDNF may have a stimulatory role on growth of sympathetic in relation to SP+ sensory nerve fibres in Co and OA, but not in RA. PMID:15608299

  13. A simple and versatile microfluidic cell density gradient generator for quantum dot cytotoxicity assay.

    PubMed

    Wu, Jing; Chen, Qiushui; Liu, Wu; Lin, Jin-Ming

    2013-05-21

    In this work, a simple and versatile microfluidic cell density gradient generator was successfully developed for cytotoxicity of quantum dots (QDs) assay. The microfluidic cell density gradient generator is composed of eight parallel channels which are respectively surrounded by 1-8 microwells with optimized length and width. The cells fall into microwells by gravity and the cell densities are obviously dependent of microwell number. In a case study, HepG2 and MCF-7 cells were successfully utilized for generating cell density gradients on the microfluidic chip. The microfluidic cell density gradient generator was proved to be easily handled, cell-friendly and could be used to conduct the subsequent cell-based assay. As a proof-of-concept, QD cytotoxicity was evaluated and the results exhibited obvious cell density-dependence. For comparison, QD cytotoxicity was also investigated with a series of cell densities infused by pipette tips. Higher reproducibility was observed on the microfluidic cell density gradient generator and cell density was demonstrated to be a vital factor in cytotoxic study. With higher efficiency, controllability and reproducibility, the microfluidic cell density gradient generator could be integrated into microfluidic analysis systems to promote chip-based biological assay.

  14. Photonic density of states of cholesteric liquid crystal cells

    NASA Astrophysics Data System (ADS)

    Gevorgyan, A. H.; Oganesyan, K. B.; Vardanyan, G. A.; Matinyan, G. K.

    2014-11-01

    Using the exact analytical expressions for the reflection and transmission matrices for the finite thickness cholesteric liquid crystal (CLC) layer, we calculated its photonic density of states (PDS) of the eigen polarizations (EPs). We investigated the influence of absorption and gain, as well as the CLC cell thickness and CLC local dielectric anisotropy on PDS. We presented the full picture of distribution of total field in the CLC layer and outside it for two EPs. The possibility of connections between the PDS and the density of the light energy accumulated in the medium was investigated, and it was shown that these characteristics had analogous spectra and, besides, the influences of the problem parameters on these characteristics were also analogous. We showed that there existed a critical value of the parameter characterizing the gain beyond which the lasing mode was quenched and the feedback vanished. We showed that in the presence of gain there existed a critical value of numbers of pitches in the CLC layer beyond which the lasing mode was again quenched and the feedback vanished, too. It is shown that the subject system can work as a low-threshold laser or a multi-position trigger.

  15. Increased power density from a spiral wound microbial fuel cell.

    PubMed

    Jia, Boyang; Hu, Dawei; Xie, Beizhen; Dong, Kun; Liu, Hong

    2013-03-15

    Using Microbial fuel cell (MFC) to convert organic and inorganic matter into electricity is of great interest for powering portable devices, which is now still limited by the output of MFC. In this study, a spiral wound MFC (SWMFC) with relatively large volume normalized surface area of separator (4.2 cm(2)/ml) was fabricated to enhance power generation. Compared with double-membrane MFC (DMMFC) and conventional double chamber MFC (DCMFC), the power density of SWMFC increased by 42% and 99% resulted from its lower internal resistance. Besides larger separator area, the better performance of SWMFC benefited from its structure sandwiching the cathodes between two separators. This point was proved again by a comparison of another DCMFC and a triple chamber MFC (TCMFC) as well as a simulation using finite element method. Moreover, the feature of SWMFC was more convenient and compact to scale up. Therefore, SWMFC provides a promising configuration for high power output as a portable power source.

  16. Effects of electron acceptors on soluble reactive phosphorus in the overlying water during algal decomposition.

    PubMed

    Wang, Jinzhi; Jiang, Xia; Zheng, Binghui; Niu, Yuan; Wang, Kun; Wang, Wenwen; Kardol, Paul

    2015-12-01

    Endogenous phosphorus (P) release from sediments is an important factor to cause eutrophication and, hence, algal bloom in lakes in China. Algal decomposition depletes dissolved oxygen (DO) and causes anaerobic conditions and therefore increases P release from sediments. As sediment P release is dependent on the iron (Fe) cycle, electron acceptors (e.g., NO3 (-), SO4 (2-), and Mn(4+)) can be utilized to suppress the reduction of Fe(3+) under anaerobic conditions and, as such, have the potential to impair the release of sediment P. Here, we used a laboratory experiment to test the effects of FeCl3, MnO2, and KNO3 on soluble reactive phosphorus (SRP) concentration and related chemical variables in the overlying water column during algal decomposition at different algal densities. Results showed that algal decomposition significantly depleted DO and thereby increased sediment Fe-bound P release. Compared with the control, addition of FeCl3 significantly decreased water SRP concentration through inhibiting sediment P release. Compared with FeCl3, addition of MnO2 has less potential to suppress sediment P release during algal decomposition. Algal decomposition has the potential for NO3 (-) removal from aquatic ecosystem through denitrification and by that alleviates the suppressing role of NO3 (-) on sediment P release. Our results indicated that FeCl3 and MnO2 could be efficient in reducing sediment P release during algal decomposition, with the strongest effect found for FeCl3; large amounts of NO3 (-) were removed from the aquatic ecosystem through denitrification during algal decomposition. Moreover, the amounts of NO3 (-) removal increased with increasing algal density.

  17. Small herbivores suppress algal accumulation on Agatti atoll, Indian Ocean

    NASA Astrophysics Data System (ADS)

    Cernohorsky, Nicole H.; McClanahan, Timothy R.; Babu, Idrees; Horsák, Michal

    2015-12-01

    Despite large herbivorous fish being generally accepted as the main group responsible for preventing algal accumulation on coral reefs, few studies have experimentally examined the relative importance of herbivore size on algal communities. This study used exclusion cages with two different mesh sizes (1 × 1 cm and 6 × 6 cm) to investigate the impact of different-sized herbivores on algal accumulation rates on the shallow (<2 m) back-reef of Agatti atoll, Lakshadweep. The fine-mesh cages excluded all visible herbivores, which had rapid and lasting effects on the benthic communities, and, after 127 d of deployment, there was a visible and significant increase in algae (mainly macroalgae) with algal volume being 13 times greater than in adjacent open areas. The coarse-mesh cages excluded larger fishes (>8 cm body depth) while allowing smaller fishes to access the plots. In contrast to the conclusions of most previous studies, the exclusion of large herbivores had no significant effect on the accumulation of benthic algae and the amount of algae present within the coarse-mesh cages was relatively consistent throughout the experimental period (around 50 % coverage and 1-2 mm height). The difference in algal accumulation between the fine-mesh and coarse-mesh cages appears to be related to the actions of small individuals from 12 herbivorous fish species (0.17 ind. m-2 and 7.7 g m-2) that were able to enter through the coarse mesh. Although restricted to a single habitat, these results suggest that when present in sufficient densities and diversity, small herbivorous fishes can prevent the accumulation of algal biomass on coral reefs.

  18. Potential of carbon nanotubes in algal biotechnology.

    PubMed

    Lambreva, Maya Dimova; Lavecchia, Teresa; Tyystjärvi, Esa; Antal, Taras Kornelievich; Orlanducci, Silvia; Margonelli, Andrea; Rea, Giuseppina

    2015-09-01

    A critical mass of knowledge is emerging on the interactions between plant cells and engineered nanomaterials, revealing the potential of plant nanobiotechnology to promote and support novel solutions for the development of a competitive bioeconomy. This knowledge can foster the adoption of new methodological strategies to empower the large-scale production of biomass from commercially important microalgae. The present review focuses on the potential of carbon nanotubes (CNTs) to enhance photosynthetic performance of microalgae by (i) widening the spectral region available for the energy conversion reactions and (ii) increasing the tolerance of microalgae towards unfavourable conditions occurring in mass production. To this end, current understanding on the mechanisms of uptake and localization of CNTs in plant cells is discussed. The available ecotoxicological data were used in an attempt to assess the feasibility of CNT-based applications in algal biotechnology, by critically correlating the experimental conditions with the observed adverse effects. Furthermore, main structural and physicochemical properties of single- and multi-walled CNTs and common approaches for the functionalization and characterization of CNTs in biological environment are presented. Here, we explore the potential that nanotechnology can offer to enhance functions of algae, paving the way for a more efficient use of photosynthetic algal systems in the sustainable production of energy, biomass and high-value compounds.

  19. Sociality in Escherichia coli: Enterochelin Is a Private Good at Low Cell Density and Can Be Shared at High Cell Density

    PubMed Central

    Scholz, Rebecca L.

    2015-01-01

    ABSTRACT Many bacteria produce secreted iron chelators called siderophores, which can be shared among cells with specific siderophore uptake systems regardless of whether the cell produces siderophores. Sharing secreted products allows freeloading, where individuals use resources without bearing the cost of production. Here we show that the Escherichia coli siderophore enterochelin is not evenly shared between producers and nonproducers. Wild-type Escherichia coli grows well in low-iron minimal medium, and an isogenic enterochelin synthesis mutant (ΔentF) grows very poorly. The enterochelin mutant grows well in low-iron medium supplemented with enterochelin. At high cell densities the ΔentF mutant can compete equally with the wild type in low-iron medium. At low cell densities the ΔentF mutant cannot compete. Furthermore, the growth rate of the wild type is unaffected by cell density. The wild type grows well in low-iron medium even at very low starting densities. Our experiments support a model where at least some enterochelin remains associated with the cells that produce it, and the cell-associated enterochelin enables iron acquisition even at very low cell density. Enterochelin that is not retained by producing cells at low density is lost to dilution. At high cell densities, cell-free enterochelin can accumulate and be shared by all cells in the group. Partial privatization is a solution to the problem of iron acquisition in low-iron, low-cell-density habitats. Cell-free enterochelin allows for iron scavenging at a distance at higher population densities. Our findings shed light on the conditions under which freeloaders might benefit from enterochelin uptake systems. IMPORTANCE Sociality in microbes has become a topic of great interest. One facet of sociality is the sharing of secreted products, such as the iron-scavenging siderophores. We present evidence that the Escherichia coli siderophore enterochelin is relatively inexpensive to produce and is

  20. A simple model for forecast of coastal algal blooms

    NASA Astrophysics Data System (ADS)

    Wong, Ken T. M.; Lee, Joseph H. W.; Hodgkiss, I. J.

    2007-08-01

    In eutrophic sub-tropical coastal waters around Hong Kong and South China, algal blooms (more often called red tides) due to the rapid growth of microscopic phytoplankton are often observed. Under favourable environmental conditions, these blooms can occur and subside over rather short time scales—in the order of days to a few weeks. Very often, these blooms are observed in weakly flushed coastal waters under calm wind conditions—with or without stratification. Based on high-frequency field observations of harmful algal blooms at two coastal mariculture zones in Hong Kong, a mathematical model has been developed to forecast algal blooms. The model accounts for algal growth, decay, settling and vertical turbulent mixing, and adopts the same assumptions as the classical Riley, Stommel and Bumpus model (Riley, G.A., Stommel, H., Bumpus, D.F., 1949. Quantitative ecology of the plankton of the western North Atlantic. Bulletin of the Bingham Oceanographic Collection Yale University 12, 1-169). It is shown that for algal blooms to occur, a vertical stability criterion, E < 4 μl2/ π2, must be satisfied, where E, μ, l are the vertical turbulent diffusivity, algal growth rate, and euphotic layer depth respectively. In addition, a minimum nutrient threshold concentration must be reached. Moreover, with a nutrient competition consideration, the type of bloom (caused by motile or non-motile species) can be classified. The model requires as input simple and readily available field measurements of water column transparency and nutrient concentration, and representative maximum algal growth rate of the motile and non-motile species. In addition, with the use of three-dimensional hydrodynamic circulation models, simple relations are derived to estimate the vertical mixing coefficient as a function of tidal range, wind speed, and density stratification. The model gives a quick assessment of the likelihood of algal bloom occurrence, and has been validated against field

  1. Relationship of dislocation density of silicon to solar cell current loss at low temperature

    NASA Technical Reports Server (NTRS)

    Mandelkorn, J.; Baraona, C. R.; Lamneck, J. H., Jr.

    1972-01-01

    Large decreases in short circuit current of silicon solar cells have been reported to occur as temperature is decreased below -60 C. Experimental results are presented which relate high dislocation density of the silicon bulk material of cells to the large current loss effect. Solar cells were made by the same processes from a variety of silicon materials, namely low-dislocation-density, high-dislocation-density float-zone, and Czochralski silicon. All cells were etched in a manner which revealed the dislocation density of the cell bulk silicon. It was found that every cell made from any of the various low-dislocation starting materials obtained from three suppliers still had a low-dislocation bulk after cell processing, and that all such cells belonged to category good. Cells made from float-zone materials showed high dislocation densities in their bulk and either fell into category poor, or had intermediate losses of short-circuit current at low temperature.

  2. Monitoring and removal of cyanobacterial toxins from drinking water by algal-activated carbon.

    PubMed

    Ibrahim, Wael M; Salim, Emad H; Azab, Yahia A; Ismail, Abdel-Hamid M

    2016-10-01

    Microcystins (MCs) are the most potent toxins that can be produced by cyanobacteria in drinking water supplies. This study investigated the abundance of toxin-producing algae in 11 drinking water treatment plants (DWTPs). A total of 26 different algal taxa were identified in treated water, from which 12% were blue green, 29% were green, and 59% were diatoms. MC levels maintained strong positive correlations with number of cyanophycean cells in raw and treated water of different DWTPs. Furthermore, the efficiency of various algal-based adsorbent columns used for the removal of these toxins was evaluated. The MCs was adsorbed in the following order: mixed algal-activated carbon (AAC) ≥ individual AAC > mixed algal powder > individual algal powder. The results showed that the AAC had the highest efficient columns capable of removing 100% dissolved MCs from drinking water samples, thereby offering an economically feasible technology for efficient removal and recovery of MCs in DWTPs.

  3. Smooth muscle myosin regulation by serum and cell density in cultured rat lung connective tissue cells.

    PubMed

    Babij, P; Zhao, J; White, S; Woodcock-Mitchell, J; Mitchell, J; Absher, M; Baldor, L; Periasamy, M; Low, R B

    1993-08-01

    RNA and protein analyses were used to detect expression of SM1 and SM2 smooth muscle myosin heavy chain (MHC) in cultured adult rat lung connective tissue cells (RL-90). Smooth muscle MHC mRNA expression in confluent cells grown in 10% serum was approximately 50% of the level in adult stomach. Similar results were obtained in cells cultured at low density (25% confluency) in 1% serum. However, in low-density cultures transferred to 10% serum for 24 h, the level of MHC mRNA decreased to approximately 20% of that in adult stomach. Smooth muscle alpha-actin showed a pattern of expression similar to that for smooth muscle MHC. Expression of nonmuscle MHC-A mRNA was higher in all culture conditions compared to stomach. MHC-A mRNA expression was less in low-density cultures in low serum and increased when low-density cultures were transferred to 10% serum for 24 h. MHC-B mRNA expression was less in low- vs. high-density cultures. In contrast to MHC-A, however, MHC-B mRNA expression in low-density cultures was higher in low serum. Immunofluorescence and immunoblotting with SM1-specific antibody demonstrated the presence of the SM1 protein isoform as well as reactivity to a protein band migrating slightly faster than SM2. These results demonstrate that cultured rat lung connective tissue cells express smooth muscle MHC and that expression is modulated by culture conditions.

  4. Luminescent Solar Concentrators in the Algal Industry

    NASA Astrophysics Data System (ADS)

    Hellier, Katie; Corrado, Carley; Carter, Sue; Detweiler, Angela; Bebout, Leslie

    2013-03-01

    Today's industry for renewable energy sources and highly efficient energy management systems is rapidly increasing. Development of increased efficiency Luminescent Solar Concentrators (LSCs) has brought about new applications for commercial interests, including greenhouses for agricultural crops. This project is taking first steps to explore the potential of LSCs to enhance production and reduce costs for algae and cyanobacteria used in biofuels and nutraceuticals. This pilot phase uses LSC filtered light for algal growth trials in greenhouses and laboratory experiments, creating specific wavelength combinations to determine effects of discrete solar light regimes on algal growth and the reduction of heating and water loss in the system. Enhancing the optimal spectra for specific algae will not only increase production, but has the potential to lessen contamination of large scale production due to competition from other algae and bacteria. Providing LSC filtered light will reduce evaporation and heating in regions with limited water supply, while the increased energy output from photovoltaic cells will reduce costs of heating and mixing cultures, thus creating a more efficient and cost effective production system.

  5. Exploiting algal NADPH oxidase for biophotovoltaic energy.

    PubMed

    Anderson, Alexander; Laohavisit, Anuphon; Blaby, Ian K; Bombelli, Paolo; Howe, Christopher J; Merchant, Sabeeha S; Davies, Julia M; Smith, Alison G

    2016-01-01

    Photosynthetic microbes exhibit light-dependent electron export across the cell membrane, which can generate electricity in biological photovoltaic (BPV) devices. How electrons are exported remains to be determined; the identification of mechanisms would help selection or generation of photosynthetic microbes capable of enhanced electrical output. We show that plasma membrane NADPH oxidase activity is a significant component of light-dependent generation of electricity by the unicellular green alga Chlamydomonas reinhardtii. NADPH oxidases export electrons across the plasma membrane to form superoxide anion from oxygen. The C. reinhardtii mutant lacking the NADPH oxidase encoded by RBO1 is impaired in both extracellular superoxide anion production and current generation in a BPV device. Complementation with the wild-type gene restores both capacities, demonstrating the role of the enzyme in electron export. Monitoring light-dependent extracellular superoxide production with a colorimetric assay is shown to be an effective way of screening for electrogenic potential of candidate algal strains. The results show that algal NADPH oxidases are important for superoxide anion production and open avenues for optimizing the biological component of these devices.

  6. Excess algal symbionts increase the susceptibility of reef corals to bleaching

    NASA Astrophysics Data System (ADS)

    Cunning, Ross; Baker, Andrew C.

    2013-03-01

    Rising ocean temperatures associated with global climate change are causing mass coral bleaching and mortality worldwide. Understanding the genetic and environmental factors that mitigate coral bleaching susceptibility may aid local management efforts to help coral reefs survive climate change. Although bleaching susceptibility depends partly on the genetic identity of a coral's algal symbionts, the effect of symbiont density, and the factors controlling it, remain poorly understood. By applying a new metric of symbiont density to study the coral Pocillopora damicornis during seasonal warming and acute bleaching, we show that symbiont cell ratio density is a function of both symbiont type and environmental conditions, and that corals with high densities are more susceptible to bleaching. Higher vulnerability of corals with more symbionts establishes a quantitative mechanistic link between symbiont density and the molecular basis for coral bleaching, and indicates that high densities do not buffer corals from thermal stress, as has been previously suggested. These results indicate that environmental conditions that increase symbiont densities, such as nutrient pollution, will exacerbate climate-change-induced coral bleaching, providing a mechanistic explanation for why local management to reduce these stressors will help coral reefs survive future warming.

  7. Algal biofuels: challenges and opportunities.

    PubMed

    Leite, Gustavo B; Abdelaziz, Ahmed E M; Hallenbeck, Patrick C

    2013-10-01

    Biodiesel production using microalgae is attractive in a number of respects. Here a number of pros and cons to using microalgae for biofuels production are reviewed. Algal cultivation can be carried out using non-arable land and non-potable water with simple nutrient supply. In addition, algal biomass productivities are much higher than those of vascular plants and the extractable content of lipids that can be usefully converted to biodiesel, triacylglycerols (TAGs) can be much higher than that of the oil seeds now used for first generation biodiesel. On the other hand, practical, cost-effective production of biofuels from microalgae requires that a number of obstacles be overcome. These include the development of low-cost, effective growth systems, efficient and energy saving harvesting techniques, and methods for oil extraction and conversion that are environmentally benign and cost-effective. Promising recent advances in these areas are highlighted.

  8. Algal blooms and public health

    SciTech Connect

    Epstein, P.R. . Harvard Medical School)

    1993-06-01

    Alterations in coastal ecology are expanding the geographic extent, frequency, magnitude, and species complexity'' of algal blooms throughout the world, increasing the threat of fish and shellfish poisonings, anoxia in marine nurseries, and of cholera. The World Health Organization and members of the medical profession have described the potential health effects of global climate change. They warn of the consequences of increased ultraviolet-B (UV-B) rays and of warming: the possible damage to agriculture and nutrition, and the impact on habitats which may alter the distribution of vector-borne and water-based infectious diseases. Algal growth due to increased nitrogen (N) and phosphorus (P) and warming are already affecting marine microflora and aquatic plants; and there is now clear evidence that marine organisms are a reservoir for enteric pathogens. The pattern of cholera in the Western Hemisphere suggests that environmental changes have already begun to influence the epidemiology of this infectious disease. 106 refs.

  9. Nucleomorphs: enslaved algal nuclei.

    PubMed

    Cavalier-Smith, T

    2002-12-01

    Nucleomorphs of cryptomonad and chlorarachnean algae are the relict, miniaturised nuclei of formerly independent red and green algae enslaved by separate eukaryote hosts over 500 million years ago. The complete 551 kb genome sequence of a cryptomonad nucleomorph confirms that cryptomonads are eukaryote-eukaryote chimeras and greatly illuminates the symbiogenetic event that created the kingdom Chromista and their alveolate protozoan sisters. Nucleomorph membranes may, like plasma membranes, be more enduring after secondary symbiogenesis than are their genomes. Partial sequences of chlorarachnean nucleomorphs indicate that genomic streamlining is limited by the mutational difficulty of removing useless introns. Nucleomorph miniaturisation emphasises that selection can dramatically reduce eukaryote genome size and eliminate most non-functional nuclear non-coding DNA. Given the differential scaling of nuclear and nucleomorph genomes with cell size, it follows that most non-coding nuclear DNA must have a bulk-sequence-independent function related to cell volume.

  10. Effects of hepatocyte growth factor on glutathione synthesis, growth, and apoptosis is cell density-dependent

    SciTech Connect

    Yang Heping; Magilnick, Nathaniel; Xia Meng; Lu, Shelly C.

    2008-01-15

    Hepatocyte growth factor (HGF) is a potent hepatocyte mitogen that exerts opposing effects depending on cell density. Glutathione (GSH) is the main non-protein thiol in mammalian cells that modulates growth and apoptosis. We previously showed that GSH level is inversely related to cell density of hepatocytes and is positively related to growth. Our current work examined whether HGF can modulate GSH synthesis in a cell density-dependent manner and how GSH in turn influence HGF's effects. We found HGF treatment of H4IIE cells increased cell GSH levels only under subconfluent density. The increase in cell GSH under low density was due to increased transcription of GSH synthetic enzymes. This correlated with increased protein levels and nuclear binding activities of c-Jun, c-Fos, p65, p50, Nrf1 and Nrf2 to the promoter region of these genes. HGF acts as a mitogen in H4IIE cells under low cell density and protects against tumor necrosis factor {alpha} (TNF{alpha})-induced apoptosis by limiting JNK activation. However, HGF is pro-apoptotic under high cell density and exacerbates TNF{alpha}-induced apoptosis by potentiating JNK activation. The increase in cell GSH under low cell density allows HGF to exert its full mitogenic effect but is not necessary for its anti-apoptotic effect.

  11. Impact of harmful algal blooms on several Lake Erie drinking water treatment facilities; methodology considerations

    EPA Science Inventory

    The propagation of cyanbacterial cells and their toxins were investigated at seven drinking water treatment plants (DWTPs) on Lake Erie were investigated with regards to harmful algal bloom (HAB) toxin concentrations, water quality variations in treatment plant influents, and pr...

  12. Functional balance between T cell chimeric receptor density and tumor associated antigen density: CTL mediated cytolysis and lymphokine production.

    PubMed

    Weijtens, M E; Hart, E H; Bolhuis, R L

    2000-01-01

    Genetically engineered expression of tumor-specific single chain antibody chimeric receptors (ch-Rec) on human T lymphocytes endow these cells with the parental monoclonal antibody (mAb) dictated tumor specificity and may be useful for clinical immuno-genetherapy. Therefore it was of importance to assess how the densities of tumor-specific receptors and tumor associated antigens (TAA), respectively, affect primary human T lymphocyte functions in relation to target cell susceptibilities to lysis. We therefore studied the functional balance between ch-Rec densities on human T lymphocytes and TAA on tumor cells. The gene construct encoding a ch-Rec derived from (1) a renal carcinoma cell (RCC) specific mouse mAb (G250), and (2) the human signal transducing Fc(epsilon)RI gamma-chain was used. To obtain ch-RecHIGH-POS and ch-RecLOW-POS T lymphocytes, two distinct retroviral vectors were used to introduce the gene constructs into primary human T lymphocytes. Levels of ch-Rec-redirected T lymphocyte mediated tumor cell lysis, as well as lymphokine production were determined using RCC lines as target/stimulator cells, which express either no or increasing densities of the TAA. A functional and dynamic balance between ch-Rec densities on cytotoxic T lymphocytes (CTLs) on the one hand and TAA densities on RCCs on the other, was found. In short, ch-RecHIGH-POS CTLs are triggered by TAAHIGH-POS as well as TAALOW-POS RCCs to lyse tumor cells and produce (IFN-gamma and TNF-alpha) lymphokine. In contrast, ch-RecLOW-POS T lymphocytes are only triggered for cytolysis and lymphokine production by relatively TAAHIGH-POS RCCs. In conclusion, (1) the activation of T lymphocyte responses is co-determined by the expression levels of the ch-Rec on T lymphocytes and the TAA on tumor cells and (2) at relatively high T lymphocyte ch-Rec expression levels the CTLs lyse tumor cells with a wide range of TAA densities. Gene Therapy (2000) 7, 35-42.

  13. Strategies for optimizing algal biology for enhanced biomass production

    SciTech Connect

    Barry, Amanda N.; Starkenburg, Shawn R.; Sayre, Richard T.

    2015-02-02

    One of the most environmentally sustainable ways to produce high-energy density (oils) feed stocks for the production of liquid transportation fuels is from biomass. Photosynthetic carbon capture combined with biomass combustion (point source) and subsequent carbon capture and sequestration has also been proposed in the intergovernmental panel on climate change report as one of the most effective and economical strategies to remediate atmospheric greenhouse gases. To maximize photosynthetic carbon capture efficiency and energy-return-on-investment, we must develop biomass production systems that achieve the greatest yields with the lowest inputs. Numerous studies have demonstrated that microalgae have among the greatest potentials for biomass production. This is in part due to the fact that all alga cells are photoautotrophic, they have active carbon concentrating mechanisms to increase photosynthetic productivity, and all the biomass is harvestable unlike plants. All photosynthetic organisms, however, convert only a fraction of the solar energy they capture into chemical energy (reduced carbon or biomass). To increase aerial carbon capture rates and biomass productivity, it will be necessary to identify the most robust algal strains and increase their biomass production efficiency often by genetic manipulation. We review recent large-scale efforts to identify the best biomass producing strains and metabolic engineering strategies to improve aerial productivity. In addition, these strategies include optimization of photosynthetic light-harvesting antenna size to increase energy capture and conversion efficiency and the potential development of advanced molecular breeding techniques. To date, these strategies have resulted in up to twofold increases in biomass productivity.

  14. The Impairment of Osteogenesis in Bone Sialoprotein (BSP) Knockout Calvaria Cell Cultures Is Cell Density Dependent

    PubMed Central

    Bouet, Guenaelle; Bouleftour, Wafa; Juignet, Laura; Linossier, Marie-Thérèse; Thomas, Mireille; Vanden-Bossche, Arnaud; Aubin, Jane E.; Vico, Laurence; Marchat, David; Malaval, Luc

    2015-01-01

    Bone sialoprotein (BSP) belongs to the "small integrin-binding ligand N-linked glycoprotein" (SIBLING) family, whose members interact with bone cells and bone mineral. BSP is strongly expressed in bone and we previously showed that BSP knockout (BSP-/-) mice have a higher bone mass than wild type (BSP+/+) littermates, with lower bone remodelling. Because baseline bone formation activity is constitutively lower in BSP-/- mice, we studied the impact of the absence of BSP on in vitro osteogenesis in mouse calvaria cell (MCC) cultures. MCC BSP-/- cultures exhibit fewer fibroblast (CFU-F), preosteoblast (CFU-ALP) and osteoblast colonies (bone nodules) than wild type, indicative of a lower number of osteoprogenitors. No mineralized colonies were observed in BSP-/- cultures, along with little/no expression of either osteogenic markers or SIBLING proteins MEPE or DMP1. Osteopontin (OPN) is the only SIBLING expressed in standard density BSP-/- culture, at higher levels than in wild type in early culture times. At higher plating density, the effects of the absence of BSP were partly rescued, with resumed expression of osteoblast markers and cognate SIBLING proteins, and mineralization of the mutant cultures. OPN expression and amount are further increased in high density BSP-/- cultures, while PHEX and CatB expression are differentiatlly regulated in a manner that may favor mineralization. Altogether, we found that BSP regulates mouse calvaria osteoblast cell clonogenicity, differentiation and activity in vitro in a cell density dependent manner, consistent with the effective skeletogenesis but the low levels of bone formation observed in vivo. The BSP knockout bone microenvironment may alter the proliferation/cell fate of early osteoprogenitors. PMID:25710686

  15. Interactions between macro-algal mats and invertebrates in the Ythan estuary, Aberdeenshire, Scotland

    NASA Astrophysics Data System (ADS)

    Raffaelli, D.

    2000-07-01

    Blooms of opportunistic green macro-algae are a common feature of coastal areas and their effects on mudflat invertebrates can be dramatic. On the Ythan estuary, Aberdeenshire, Scotland, we have carried out a number of manipulative field experiments designed to evaluate the effects on invertebrates of different species of macro-algae with contrasting ecologies, and the effects of invertebrates on the development of the blooms. Macro-algal mats were found to have dramatic nega- tive effects on the density of the amphipod Corophium volutator, with higher algal biomasses having greater impact. The mechanism for this interaction seems to be interference by the algal filaments with the feeding behaviour of the amphipod. In contrast, the polychaete Capitella spp. increases in abundance under macro-algal mats due to enrichment of the sediment with organic material. These two interactions are seen at all scales, in areas of less than 1 m2 to the scale of the entire estuary, irrespective of the species composition of the macro- algal mats. Bioturbation by Corophium and grazing by the snail Hydrobia ulvae had little effect on macro-algal biomass, but there were less algae when the polychaete Nereis diversicolor was present. The most significant interaction in this system is the pronounced negative impact of algal mats on the abundance of Corophium, probably the most important invertebrate species in the diets of the estuary's shorebirds, fish and epibenthic crustaceans.

  16. Information in a Network of Neuronal Cells: Effect of Cell Density and Short-Term Depression

    PubMed Central

    Onesto, Valentina; Cosentino, Carlo; Di Fabrizio, Enzo; Cesarelli, Mario; Amato, Francesco; Gentile, Francesco

    2016-01-01

    Neurons are specialized, electrically excitable cells which use electrical to chemical signals to transmit and elaborate information. Understanding how the cooperation of a great many of neurons in a grid may modify and perhaps improve the information quality, in contrast to few neurons in isolation, is critical for the rational design of cell-materials interfaces for applications in regenerative medicine, tissue engineering, and personalized lab-on-a-chips. In the present paper, we couple an integrate-and-fire model with information theory variables to analyse the extent of information in a network of nerve cells. We provide an estimate of the information in the network in bits as a function of cell density and short-term depression time. In the model, neurons are connected through a Delaunay triangulation of not-intersecting edges; in doing so, the number of connecting synapses per neuron is approximately constant to reproduce the early time of network development in planar neural cell cultures. In simulations where the number of nodes is varied, we observe an optimal value of cell density for which information in the grid is maximized. In simulations in which the posttransmission latency time is varied, we observe that information increases as the latency time decreases and, for specific configurations of the grid, it is largely enhanced in a resonance effect. PMID:27403421

  17. Measurement of mass, density, and volume during the cell cycle of yeast

    PubMed Central

    Bryan, Andrea K.; Goranov, Alexi; Amon, Angelika; Manalis, Scott R.

    2010-01-01

    Cell growth comprises changes in both mass and volume—two processes that are distinct, yet coordinated through the cell cycle. Understanding this relationship requires a means for measuring each of the cell’s three basic physical parameters: mass, volume, and the ratio of the two, density. The suspended microchannel resonator weighs single cells with a precision in mass of 0.1% for yeast. Here we use the suspended microchannel resonator with a Coulter counter to measure the mass, volume, and density of budding yeast cells through the cell cycle. We observe that cell density increases prior to bud formation at the G1/S transition, which is consistent with previous measurements using density gradient centrifugation. To investigate the origin of this density increase, we monitor relative density changes of growing yeast cells. We find that the density increase requires energy, function of the protein synthesis regulator target of rapamycin, passage through START (commitment to cell division), and an intact actin cytoskeleton. Although we focus on basic cell cycle questions in yeast, our techniques are suitable for most nonadherent cells and subcellular particles to characterize cell growth in a variety of applications. PMID:20080562

  18. Ganglion cells density and retinal resolution in the sea otter, Enhydra lutris.

    PubMed

    Mass, A M; Supin, A Y

    2000-03-01

    The topographic distribution, density, and size of ganglion cells were studied in retinal wholemounts of the sea otter, Enhydra lutris. The cell distribution showed a well defined horizontal streak of higher cell density, and within this streak, a narrow area of the highest cell density. The peak cell density in this area ranged from 4050 to 4400 cells/mm(2), with a mean of 4225 cells/mm(2). The ganglion cell size ranged from 7 microm to 47 microm but the majority of cells were 7 to 30 microm. Cell size distribution revealed three size groups: 7-16, 17-28, and 29-47 microm. The highest-density area contained mainly small (7-16 microm) cells. The cell-density data predict a retinal resolution around 7' in water. Retinal organization in the sea otter exhibits more properties common with terrestrial rather than aquatic mammals, both in terms of ganglion cell characteristics and in terms of their topographic distribution.

  19. Methods for removing contaminants from algal oil

    SciTech Connect

    Lupton, Francis Stephen

    2016-09-27

    Methods for removing contaminants from algal oil are provided. In an embodiment, a method comprises the steps of combining a sulfuric acid-aqueous solution that has a pH of about 1 or less with a contaminant-containing algal oil at treatment conditions effective to form an effluent. The effluent comprises a treated algal oil phase and contaminants in an acidic aqueous phase. The contaminants comprise metals, phosphorus, or combinations thereof. The acidic aqueous phase is removed from the effluent to form a contaminant-depleted algal oil.

  20. The dynamics of heterotrophic algal cultures.

    PubMed

    De la Hoz Siegler, H; Ben-Zvi, A; Burrell, R E; McCaffrey, W C

    2011-05-01

    In this work, the time varying characteristics of microalgal cultures are investigated. Microalgae are a promising source of biofuels and other valuable chemicals; a better understanding of their dynamic behavior is, however, required to facilitate process scale-up, optimization and control. Growth and oil production rates are evaluated as a function of carbon and nitrogen sources concentration. It is found that nitrogen has a major role in controlling the productivity of microalgae. Moreover, it is shown that there exists a nitrogen source concentration at which biomass and oil production can be maximized. A mathematical model that describes the effect of nitrogen and carbon source on growth and oil production is proposed. The model considers the uncoupling between nutrient uptake and growth, a characteristic of algal cells. Validity of the proposed model is tested on fed-batch cultures.

  1. Multicellular automaticity of cardiac cell monolayers: effects of density and spatial distribution of pacemaker cells

    NASA Astrophysics Data System (ADS)

    Elber Duverger, James; Boudreau-Béland, Jonathan; Le, Minh Duc; Comtois, Philippe

    2014-11-01

    Self-organization of pacemaker (PM) activity of interconnected elements is important to the general theory of reaction-diffusion systems as well as for applications such as PM activity in cardiac tissue to initiate beating of the heart. Monolayer cultures of neonatal rat ventricular myocytes (NRVMs) are often used as experimental models in studies on cardiac electrophysiology. These monolayers exhibit automaticity (spontaneous activation) of their electrical activity. At low plated density, cells usually show a heterogeneous population consisting of PM and quiescent excitable cells (QECs). It is therefore highly probable that monolayers of NRVMs consist of a heterogeneous network of the two cell types. However, the effects of density and spatial distribution of the PM cells on spontaneous activity of monolayers remain unknown. Thus, a simple stochastic pattern formation algorithm was implemented to distribute PM and QECs in a binary-like 2D network. A FitzHugh-Nagumo excitable medium was used to simulate electrical spontaneous and propagating activity. Simulations showed a clear nonlinear dependency of spontaneous activity (occurrence and amplitude of spontaneous period) on the spatial patterns of PM cells. In most simulations, the first initiation sites were found to be located near the substrate boundaries. Comparison with experimental data obtained from cardiomyocyte monolayers shows important similarities in the position of initiation site activity. However, limitations in the model that do not reflect the complex beat-to-beat variation found in experiments indicate the need for a more realistic cardiomyocyte representation.

  2. Recent progress and future challenges in algal biofuel production

    PubMed Central

    Shurin, Jonathan B.; Burkart, Michael D.; Mayfield, Stephen P.

    2016-01-01

    Modern society is fueled by fossil energy produced millions of years ago by photosynthetic organisms. Cultivating contemporary photosynthetic producers to generate energy and capture carbon from the atmosphere is one potential approach to sustaining society without disrupting the climate. Algae, photosynthetic aquatic microorganisms, are the fastest growing primary producers in the world and can therefore produce more energy with less land, water, and nutrients than terrestrial plant crops. We review recent progress and challenges in developing bioenergy technology based on algae. A variety of high-value products in addition to biofuels can be harvested from algal biomass, and these may be key to developing algal biotechnology and realizing the commercial potential of these organisms. Aspects of algal biology that differentiate them from plants demand an integrative approach based on genetics, cell biology, ecology, and evolution. We call for a systems approach to research on algal biotechnology rooted in understanding their biology, from the level of genes to ecosystems, and integrating perspectives from physical, chemical, and social sciences to solve one of the most critical outstanding technological problems. PMID:27781084

  3. Continuous butanol fermentation from xylose with high cell density by cell recycling system.

    PubMed

    Zheng, Jin; Tashiro, Yukihiro; Yoshida, Tsuyoshi; Gao, Ming; Wang, Qunhui; Sonomoto, Kenji

    2013-02-01

    A continuous butanol production system with high-density Clostridium saccharoperbutylacetonicum N1-4 generated by cell recycling was established to examine the characteristics of butanol fermentation from xylose. In continuous culture without cell recycling, cell washout was avoided by maintaining pH>5.6 at a dilution rate of 0.26 h(-1), indicating pH control was critical to this experiment. Subsequently, continuous culture with cell recycling increased cell concentration to 17.4 g L(-1), which increased butanol productivity to 1.20 g L(-1) h(-1) at a dilution rate of 0.26 h(-1) from 0.529 g L(-1) h(-1) without cell recycling. The effect of dilution rates on butanol production was also investigated in continuous culture with cell recycling. Maximum butanol productivity (3.32 g L(-1) h(-1)) was observed at a dilution rate of 0.78 h(-1), approximately 6-fold higher than observed in continuous culture without cell recycling (0.529 g L(-1) h(-1)).

  4. Raman microspectroscopy based sensor of algal lipid unsaturation

    NASA Astrophysics Data System (ADS)

    Samek, Ota; Pilát, Zdeněk; Jonáš, Alexandr; Zemánek, Pavel; Šerý, Mojmír; Ježek, Jan; Bernatová, Silvie; Nedbal, Ladislav; Trtílek, Martin

    2011-05-01

    Raman spectroscopy is a powerful tool for chemical analysis. This technique can elucidate fundamental questions about the metabolic processes and intercellular variability on a single cell level. Therefore, Raman spectroscopy can significantly contribute to the study and use of microalgae in systems biology and biofuel technology. Raman spectroscopy can be combined with optical tweezers. We have employed microfluidic system to deliver the sampled microalgae to the Raman-tweezers. This instrument is able to measure chemical composition of cells and to track metabolic processes in vivo, in real-time and label-free making it possible to detect population variability in a wide array of traits. Moreover, employing an active sorting switch, cells can be separated depending on input parameters obtained from Raman spectra. We focus on algal lipids which are promising potential products for biofuel as well as for nutrition. Important parameter characterizing the algal lipids is the degree of unsaturation of the constituent fatty acids. We demonstrate the capacity of our Raman tweezers based sensor to sort cells according to the degree of unsaturation in lipid storage bodies of individual living algal cells.

  5. Cell receptor and surface ligand density effects on dynamic states of adhering circulating tumor cells.

    PubMed

    Zheng, Xiangjun; Cheung, Luthur Siu-Lun; Schroeder, Joyce A; Jiang, Linan; Zohar, Yitshak

    2011-10-21

    Dynamic states of cancer cells moving under shear flow in an antibody-functionalized microchannel are investigated experimentally and theoretically. The cell motion is analyzed with the aid of a simplified physical model featuring a receptor-coated rigid sphere moving above a solid surface with immobilized ligands. The motion of the sphere is described by the Langevin equation accounting for the hydrodynamic loadings, gravitational force, receptor-ligand bindings, and thermal fluctuations; the receptor-ligand bonds are modeled as linear springs. Depending on the applied shear flow rate, three dynamic states of cell motion have been identified: (i) free motion, (ii) rolling adhesion, and (iii) firm adhesion. Of particular interest is the fraction of captured circulating tumor cells, defined as the capture ratio, via specific receptor-ligand bonds. The cell capture ratio decreases with increasing shear flow rate with a characteristic rate. Based on both experimental and theoretical results, the characteristic flow rate increases monotonically with increasing either cell-receptor or surface-ligand density within certain ranges. Utilizing it as a scaling parameter, flow-rate dependent capture ratios for various cell-surface combinations collapse onto a single curve described by an exponential formula.

  6. Flagellum density regulates Proteus mirabilis swarmer cell motility in viscous environments.

    PubMed

    Tuson, Hannah H; Copeland, Matthew F; Carey, Sonia; Sacotte, Ryan; Weibel, Douglas B

    2013-01-01

    Proteus mirabilis is an opportunistic pathogen that is frequently associated with urinary tract infections. In the lab, P. mirabilis cells become long and multinucleate and increase their number of flagella as they colonize agar surfaces during swarming. Swarming has been implicated in pathogenesis; however, it is unclear how energetically costly changes in P. mirabilis cell morphology translate into an advantage for adapting to environmental changes. We investigated two morphological changes that occur during swarming--increases in cell length and flagellum density--and discovered that an increase in the surface density of flagella enabled cells to translate rapidly through fluids of increasing viscosity; in contrast, cell length had a small effect on motility. We found that swarm cells had a surface density of flagella that was ∼5 times larger than that of vegetative cells and were motile in fluids with a viscosity that inhibits vegetative cell motility. To test the relationship between flagellum density and velocity, we overexpressed FlhD(4)C(2), the master regulator of the flagellar operon, in vegetative cells of P. mirabilis and found that increased flagellum density produced an increase in cell velocity. Our results establish a relationship between P. mirabilis flagellum density and cell motility in viscous environments that may be relevant to its adaptation during the infection of mammalian urinary tracts and movement in contact with indwelling catheters.

  7. Isoelectric focusing of red blood cells in a density gradient stabilized column

    NASA Technical Reports Server (NTRS)

    Smolka, A. J. K.; Miller, T. Y.

    1980-01-01

    The effects of Ficoll and cell application pH on red blood cell electrophoretic mobility and focusing pH were investigated by focusing cells in a density gradient stabilized column. Sample loading, cell dispersion, column conductivity, resolution of separation, and the effect of Ampholines were examined.

  8. Collagen Matrix Density Drives the Metabolic Shift in Breast Cancer Cells.

    PubMed

    Morris, Brett A; Burkel, Brian; Ponik, Suzanne M; Fan, Jing; Condeelis, John S; Aguirre-Ghiso, Julio A; Castracane, James; Denu, John M; Keely, Patricia J

    2016-11-01

    Increased breast density attributed to collagen I deposition is associated with a 4-6 fold increased risk of developing breast cancer. Here, we assessed cellular metabolic reprogramming of mammary carcinoma cells in response to increased collagen matrix density using an in vitro 3D model. Our initial observations demonstrated changes in functional metabolism in both normal mammary epithelial cells and mammary carcinoma cells in response to changes in matrix density. Further, mammary carcinoma cells grown in high density collagen matrices displayed decreased oxygen consumption and glucose metabolism via the tricarboxylic acid (TCA) cycle compared to cells cultured in low density matrices. Despite decreased glucose entry into the TCA cycle, levels of glucose uptake, cell viability, and ROS were not different between high and low density matrices. Interestingly, under high density conditions the contribution of glutamine as a fuel source to drive the TCA cycle was significantly enhanced. These alterations in functional metabolism mirrored significant changes in the expression of metabolic genes involved in glycolysis, oxidative phosphorylation, and the serine synthesis pathway. This study highlights the broad importance of the collagen microenvironment to cellular expression profiles, and shows that changes in density of the collagen microenvironment can modulate metabolic shifts of cancer cells.

  9. Estimation of current density distribution of PAFC by analysis of cell exhaust gas

    SciTech Connect

    Kato, S.; Seya, A.; Asano, A.

    1996-12-31

    To estimate distributions of Current densities, voltages, gas concentrations, etc., in phosphoric acid fuel cell (PAFC) stacks, is very important for getting fuel cells with higher quality. In this work, we leave developed a numerical simulation tool to map out the distribution in a PAFC stack. And especially to Study Current density distribution in the reaction area of the cell, we analyzed gas composition in several positions inside a gas outlet manifold of the PAFC stack. Comparing these measured data with calculated data, the current density distribution in a cell plane calculated by the simulation, was certified.

  10. Algal Bloom Detection from HICO

    NASA Astrophysics Data System (ADS)

    Amin, Ruhul; Gould, Richard

    2014-05-01

    Ocean color satellites provide daily, global views of marine bio-optical properties in the upper ocean at various spatial scales. The most productive area of the global ocean is the coastal zone which is heavily impacted by urban and agricultural runoff, transportation, recreation, and oil and gas production. In recent years, harmful algal blooms (HABs) have become one of the serious environmental problems in the coastal areas on a global scale. The global nature of the problem has expanded in its frequency, severity, and extent over the last several decades. Human activities and population increases have contributed to an increase in various toxic and noxious algal species in the coastal regions worldwide. Eutrophication in estuaries and coastal waters is believed to be the major factor causing HABs. In this study, we assess the applicability of the Red Band Difference (RBD) HAB detection algorithm on data from the Hyperspectral Imager for the Coastal Ocean (HICO). Our preliminary results show that due to various uncertainties such as atmospheric correction, calibration and possibly also the relatively low signal-to-noise ratio of HICO for fluorescence detection, it is difficult to extract the fluorescence portion of the reflectance spectrum that RBD uses for bloom detection. We propose an improved bloom detection technique for HICO using red and NIR bands. Our results are validated using other space-borne and ground based measurements.

  11. NREL Algal Biofuels Projects and Partnerships

    SciTech Connect

    2016-10-01

    This fact sheet highlights several algal biofuels research and development projects focused on improving the economics of the algal biofuels production process. These projects should serve as a foundation for the research efforts toward algae as a source of fuels and other chemicals.

  12. Relationship of dislocation density of silicon to solar cell current loss at low temperature.

    NASA Technical Reports Server (NTRS)

    Mandelkorn, J.; Baraona, C. R.; Lamneck, J. H., Jr.

    1972-01-01

    Large decreases in short circuit current of silicon solar cells have been reported to occur as temperature is decreased below -60 C. Experimental results are presented which relate high dislocation density of the silicon bulk material of cells to the large current loss effect. These results reveal a direct relationship between low bulk dislocation density and low current loss at low temperature. Oxygen content does not appear to play a significant role in the low temperature-large current loss effect, since some Czochralski cells did not suffer from this effect whereas some float-zone cells did. Other float-zone silicon cells had only medium current losses at low temperature despite their high bulk dislocation density. It appears that use of low-dislocation-density silicon can eliminate the current loss problem in low temperature cell operation.

  13. Process for selection of Oxygen-tolerant algal mutants that produce H.sub.2

    DOEpatents

    Ghirardi, Maria L.; Seibert, Michael

    1999-01-01

    A process for selection of oxygen-tolerant, H.sub.2 -producing algal mutant cells comprising: (a) growing algal cells photoautotrophically under fluorescent light to mid log phase; (b) inducing algal cells grown photoautrophically under fluorescent light to mid log phase in step (a) anaerobically by (1) resuspending the cells in a buffer solution and making said suspension anaerobic with an inert gas; (2) incubating the suspension in the absence of light at ambient temperature; (c) treating the cells from step (b) with metronidazole, sodium azide, and added oxygen to controlled concentrations in the presence of white light. (d) washing off metronidazole and sodium azide to obtain final cell suspension; (e) plating said final cell suspension on a minimal medium and incubating in light at a temperature sufficient to enable colonies to appear; (f) counting the number of colonies to determine the percent of mutant survivors; and (g) testing survivors to identify oxygen-tolerant H.sub.2 -producing mutants.

  14. High CD46 receptor density determines preferential killing of tumor cells by oncolytic measles virus.

    PubMed

    Anderson, Bambi D; Nakamura, Takafumi; Russell, Stephen J; Peng, Kah-Whye

    2004-07-15

    Live attenuated Edmonston B strain of measles virus (MV-Edm) is a potent and specific oncolytic agent, but the mechanism underlying its tumor selectivity is unknown. The virus causes cytopathic effects (CPEs) of extensive syncytial formation in tumor cells but minimal damage or cell killing in normal cells. The CPE is dependent on expression of viral proteins and the presence of CD46, the major cellular receptor of MV-Edm. Using a virally encoded soluble marker peptide to provide a quantitative readout of the level of viral gene expression, we determined that tumor cells and normal cells expressed comparable levels of viral proteins. CD46 mediates virus attachment, entry, and virus-induced cell-to-cell fusion. Using engineered cells expressing a range of CD46 densities, we determined that whereas virus entry increased progressively with CD46 density, cell fusion was minimal at low receptor densities but increased dramatically above a threshold density of CD46 receptors. It is well established that tumor cells express abundant CD46 receptors on their surfaces compared with their normal counterparts. Thus, at low CD46 densities typical of normal cells, infection occurs, but intercellular fusion is negligible. At higher densities typical of tumor cells, infection leads to extensive cell fusion. Intercellular fusion also results in enhancement of viral gene expression through recruitment of neighboring uninfected cells into the syncytium, further amplifying the CPE. Discrimination between high and low CD46 receptor density provides a compelling basis for the oncolytic specificity of MV-Edm and establishes MV-Edm as a promising CD46-targeted cancer therapeutic agent.

  15. Effects of cell density, light intensity and mixing on Undaria pinnatifida gametophyte activity in a photobioreactor.

    PubMed

    Zou, Ning; Zhou, Baicheng; Li, Bingjun; Sun, Donghong; Zeng, Chengkui

    2003-07-01

    An on-line controlled 7 l sterilizable photobioreactor was used for the optimisation of a culture of gametophytes of Undaria pinnatifida. The gametophytes, which had been stored for three years in a culture cabinet at 16 degrees C, could rapidly grow in the photobioreactor under controlled conditions. The rate of increase of dissolved oxygen and pH were used to monitor the photosynthetic activity. Optimal gametophytes density changed varying the light intensity. The optimal cell densities were 3.24 and 3.45 g FW l(-1) when the cultures were exposed to 61.7 and 82.3 microE m(-2) s(-1), respectively. The optimal cell density was higher under a high photon flux density (PFD) than under low PFD. On the other hand, the optimal light intensities were different for different cell density cultures. The light saturation point was higher at high cell density cultures than at low cell density cultures. The optimal rotational speed was 150 rpm for high cell density culture in the photobioreactor.

  16. Constraints to commercialization of algal fuels.

    PubMed

    Chisti, Yusuf

    2013-09-10

    Production of algal crude oil has been achieved in various pilot scale facilities, but whether algal fuels can be produced in sufficient quantity to meaningfully displace petroleum fuels, has been largely overlooked. Limitations to commercialization of algal fuels need to be understood and addressed for any future commercialization. This review identifies the major constraints to commercialization of transport fuels from microalgae. Algae derived fuels are expensive compared to petroleum derived fuels, but this could change. Unfortunately, improved economics of production are not sufficient for an environmentally sustainable production, or its large scale feasibility. A low-cost point supply of concentrated carbon dioxide colocated with the other essential resources is necessary for producing algal fuels. An insufficiency of concentrated carbon dioxide is actually a major impediment to any substantial production of algal fuels. Sustainability of production requires the development of an ability to almost fully recycle the phosphorous and nitrogen nutrients that are necessary for algae culture. Development of a nitrogen biofixation ability to support production of algal fuels ought to be an important long term objective. At sufficiently large scale, a limited supply of freshwater will pose a significant limitation to production even if marine algae are used. Processes for recovering energy from the algal biomass left after the extraction of oil, are required for achieving a net positive energy balance in the algal fuel oil. The near term outlook for widespread use of algal fuels appears bleak, but fuels for niche applications such as in aviation may be likely in the medium term. Genetic and metabolic engineering of microalgae to boost production of fuel oil and ease its recovery, are essential for commercialization of algal fuels. Algae will need to be genetically modified for improved photosynthetic efficiency in the long term.

  17. Physiological responses to acid stress by Saccharomyces cerevisiae when applying high initial cell density

    PubMed Central

    Guo, Zhong-peng; Olsson, Lisbeth

    2016-01-01

    High initial cell density is used to increase volumetric productivity and shorten production time in lignocellulosic hydrolysate fermentation. Comparison of physiological parameters in high initial cell density cultivation of Saccharomyces cerevisiae in the presence of acetic, formic, levulinic and cinnamic acids demonstrated general and acid-specific responses of cells. All the acids studied impaired growth and inhibited glycolytic flux, and caused oxidative stress and accumulation of trehalose. However, trehalose may play a role other than protecting yeast cells from acid-induced oxidative stress. Unlike the other acids, cinnamic acid did not cause depletion of cellular ATP, but abolished the growth of yeast on ethanol. Compared with low initial cell density, increasing initial cell density reduced the lag phase and improved the bioconversion yield of cinnamic acid during acid adaptation. In addition, yeast cells were able to grow at elevated concentrations of acid, probable due to the increase in phenotypic cell-to-cell heterogeneity in large inoculum size. Furthermore, the specific growth rate and the specific rates of glucose consumption and metabolite production were significantly lower than at low initial cell density, which was a result of the accumulation of a large fraction of cells that persisted in a viable but non-proliferating state. PMID:27620460

  18. Cell Growth on ("Janus") Density Gradients of Bifunctional Zeolite L Crystals.

    PubMed

    Kehr, Nermin Seda; Motealleh, Andisheh; Schäfer, Andreas H

    2016-12-28

    Nanoparticle density gradients on surfaces have attracted interest as two-dimensional material surfaces that can mimic the complex nano-/microstructure of the native extracellular matrix, including its chemical and physical gradients, and can therefore be used to systematically study cell-material interactions. In this respect, we report the preparation of density gradients made of bifunctional zeolite L crystals on glass surfaces and the effects of the density gradient and biopolymer functionalization of zeolite L crystals on cell adhesion. We also describe how we created "Janus" density gradient surfaces by gradually depositing two different types of zeolite L crystals that were functionalized and loaded with different chemical groups and guest molecules onto the two distinct sides of the same glass substrate. Our results show that more cells adhered on the density gradient of biopolymer-coated zeolites than on uncoated ones. The number of adhered cells increased up to a certain surface coverage of the glass by the zeolite L crystals, but then it decreased beyond the zeolite density at which a higher surface coverage decreased fibroblast cell adhesion and spreading. Additionally, cell experiments showed that cells gradually internalized the guest-molecule-loaded zeolite L crystals from the underlying density gradient containing bifunctional zeolite L crystals.

  19. Topographical guidance of 3D tumor cell migration at an interface of collagen densities.

    PubMed

    Bordeleau, Francois; Tang, Lauren N; Reinhart-King, Cynthia A

    2013-12-01

    During cancer progression, metastatic cells leave the primary tumor and invade into the fibrous extracellular matrix (ECM) within the surrounding stroma. This ECM network is highly heterogeneous, and interest in understanding how this network can affect cell behavior has increased in the past several decades. However, replicating this heterogeneity has proven challenging. Here, we designed and utilized a method to create a well-defined interface between two distinct regions of high- and low-density collagen gels to mimic the heterogeneities in density found in the tumor stroma. We show that cells will invade preferentially from the high-density side into the low-density side. We also demonstrate that the net cell migration is a function of the density of the collagen in which the cells are embedded, and the difference in density between the two regions has minimal effect on cell net displacement and distance travelled. Our data further indicate that a low-to-high density interface promotes directional migration and induces formation of focal adhesion on the interface surface. Together, the current results demonstrate how ECM heterogeneities, in the form of interfacial boundaries, can affect cell migration.

  20. Application of dielectric spectroscopy for monitoring high cell density in monoclonal antibody producing CHO cell cultivations.

    PubMed

    Párta, László; Zalai, Dénes; Borbély, Sándor; Putics, Akos

    2014-02-01

    The application of dielectric spectroscopy was frequently investigated as an on-line cell culture monitoring tool; however, it still requires supportive data and experience in order to become a robust technique. In this study, dielectric spectroscopy was used to predict viable cell density (VCD) at industrially relevant high levels in concentrated fed-batch culture of Chinese hamster ovary cells producing a monoclonal antibody for pharmaceutical purposes. For on-line dielectric spectroscopy measurements, capacitance was scanned within a wide range of frequency values (100-19,490 kHz) in six parallel cell cultivation batches. Prior to detailed mathematical analysis of the collected data, principal component analysis (PCA) was applied to compare dielectric behavior of the cultivations. PCA analysis resulted in detecting measurement disturbances. By using the measured spectroscopic data, partial least squares regression (PLS), Cole-Cole, and linear modeling were applied and compared in order to predict VCD. The Cole-Cole and the PLS model provided reliable prediction over the entire cultivation including both the early and decline phases of cell growth, while the linear model failed to estimate VCD in the later, declining cultivation phase. In regards to the measurement error sensitivity, remarkable differences were shown among PLS, Cole-Cole, and linear modeling. VCD prediction accuracy could be improved in the runs with measurement disturbances by first derivative pre-treatment in PLS and by parameter optimization of the Cole-Cole modeling.

  1. Ultrasound pretreatment of filamentous algal biomass for enhanced biogas production.

    PubMed

    Lee, Kwanyong; Chantrasakdakul, Phrompol; Kim, Daegi; Kong, Mingeun; Park, Ki Young

    2014-06-01

    The filamentous alga Hydrodictyon reticulatum harvested from a bench-scale wastewater treatment pond was used to evaluate biogas production after ultrasound pretreatment. The effects of ultrasound pretreatment at a range of 10-5000 J/mL were tested with harvested H. reticulatum. Cell disruption by ultrasound was successful and showed a higher degree of disintegration at a higher applied energy. The range of 10-5000 J/mL ultrasound was able to disintegrated H. reticulatum and the soluble COD was increased from 250 mg/L to 1000 mg/L at 2500 J/mL. The disintegrated algal biomass was digested for biogas production in batch experiments. Both cumulative gas generation and volatile solids reduction data were obtained during the digestion. Cell disintegration due to ultrasound pretreatment increased the specific biogas production and degradation rates. Using the ultrasound approach, the specific methane production at a dose of 40 J/mL increased up to 384 mL/g-VS fed that was 2.3 times higher than the untreated sample. For disintegrated samples, the volatile solids reduction was greater with increased energy input, and the degradation increased slightly to 67% at a dose of 50 J/mL. The results also indicate that disintegration of the algal cells is the essential step for efficient anaerobic digestion of algal biomass.

  2. Proteolytic and non-proteolytic regulation of collective cell invasion: tuning by ECM density and organization.

    PubMed

    Kumar, Sandeep; Kapoor, Aastha; Desai, Sejal; Inamdar, Mandar M; Sen, Shamik

    2016-02-02

    Cancer cells manoeuvre through extracellular matrices (ECMs) using different invasion modes, including single cell and collective cell invasion. These modes rely on MMP-driven ECM proteolysis to make space for cells to move. How cancer-associated alterations in ECM influence the mode of invasion remains unclear. Further, the sensitivity of the two invasion modes to MMP dynamics remains unexplored. In this paper, we address these open questions using a multiscale hybrid computational model combining ECM density-dependent MMP secretion, MMP diffusion, ECM degradation by MMP and active cell motility. Our results demonstrate that in randomly aligned matrices, collective cell invasion is more efficient than single cell invasion. Although increase in MMP secretion rate enhances invasiveness independent of cell-cell adhesion, sustenance of collective invasion in dense matrices requires high MMP secretion rates. However, matrix alignment can sustain both single cell and collective cell invasion even without ECM proteolysis. Similar to our in-silico observations, increase in ECM density and MMP inhibition reduced migration of MCF-7 cells embedded in sandwich gels. Together, our results indicate that apart from cell intrinsic factors (i.e., high cell-cell adhesion and MMP secretion rates), ECM density and organization represent two important extrinsic parameters that govern collective cell invasion and invasion plasticity.

  3. The density of the cell sap and endoplasm of Nitellopsis and Chara

    NASA Technical Reports Server (NTRS)

    Wayne, R.; Staves, M. P.

    1991-01-01

    We measured the densities of the cell sap, endoplasm and cell wall of Nitellopsis obtusa and Chara corallina using interference microscopy, refractometry, immersion refractometry, equilibrium sedimentation and chemical microanalysis techniques. These values are important for the determination of many rheological properties of the cytoplasm as well as for understanding buoyancy regulation, dispersal mechanisms and how cells respond to gravity. The average densities of the cell sap, endoplasm and cell wall are 1,006.9, 1,016.7 and 1,371 kg m-3 for Nitellopsis and 1,005.0, 1,013.9, and 1,355.3 kg m-3 for Chara.

  4. Simulated Macro-Algal Outbreak Triggers a Large-Scale Response on Coral Reefs

    PubMed Central

    Welsh, Justin Q.; Bellwood, David R.

    2015-01-01

    Ecosystem degradation has become common throughout the world. On coral reefs, macroalgal outbreaks are one of the most widely documented signs of degradation. This study simulated local-scale degradation on a healthy coral reef to determine how resident taxa, with the potential to reverse algal outbreaks, respond. We utilized a combination of acoustic and video monitoring to quantify changes in the movements and densities, respectively, of coral reef herbivores following a simulated algal outbreak. We found an unprecedented accumulation of functionally important herbivorous taxa in response to algal increases. Herbivore densities increased by 267% where algae were present. The increase in herbivore densities was driven primarily by an accumulation of the browsing taxa Naso unicornis and Kyphosus vaigiensis, two species which are known to be important in removing macroalgae and which may be capable of reversing algal outbreaks. However, resident individuals at the site of algal increase exhibited no change in their movements. Instead, analysis of the size classes of the responding individuals indicates that large functionally-important non-resident individuals changed their movement patterns to move in and feed on the algae. This suggests that local-scale reef processes may not be sufficient to mitigate the effects of local degradation and highlights the importance of mobile links and cross-scale interactions. PMID:26171788

  5. Density of founder cells affects spatial pattern formation and cooperation in Bacillus subtilis biofilms.

    PubMed

    van Gestel, Jordi; Weissing, Franz J; Kuipers, Oscar P; Kovács, Akos T

    2014-10-01

    In nature, most bacteria live in surface-attached sedentary communities known as biofilms. Biofilms are often studied with respect to bacterial interactions. Many cells inhabiting biofilms are assumed to express 'cooperative traits', like the secretion of extracellular polysaccharides (EPS). These traits can enhance biofilm-related properties, such as stress resilience or colony expansion, while being costly to the cells that express them. In well-mixed populations cooperation is difficult to achieve, because non-cooperative individuals can reap the benefits of cooperation without having to pay the costs. The physical process of biofilm growth can, however, result in the spatial segregation of cooperative from non-cooperative individuals. This segregation can prevent non-cooperative cells from exploiting cooperative neighbors. Here we examine the interaction between spatial pattern formation and cooperation in Bacillus subtilis biofilms. We show, experimentally and by mathematical modeling, that the density of cells at the onset of biofilm growth affects pattern formation during biofilm growth. At low initial cell densities, co-cultured strains strongly segregate in space, whereas spatial segregation does not occur at high initial cell densities. As a consequence, EPS-producing cells have a competitive advantage over non-cooperative mutants when biofilms are initiated at a low density of founder cells, whereas EPS-deficient cells have an advantage at high cell densities. These results underline the importance of spatial pattern formation for competition among bacterial strains and the evolution of microbial cooperation.

  6. Heterotypic interactions regulate cell shape and density during color pattern formation in zebrafish

    PubMed Central

    Mahalwar, Prateek; Singh, Ajeet Pratap; Fadeev, Andrey; Nüsslein-Volhard, Christiane

    2016-01-01

    ABSTRACT The conspicuous striped coloration of zebrafish is produced by cell-cell interactions among three different types of chromatophores: black melanophores, orange/yellow xanthophores and silvery/blue iridophores. During color pattern formation xanthophores undergo dramatic cell shape transitions and acquire different densities, leading to compact and orange xanthophores at high density in the light stripes, and stellate, faintly pigmented xanthophores at low density in the dark stripes. Here, we investigate the mechanistic basis of these cell behaviors in vivo, and show that local, heterotypic interactions with dense iridophores regulate xanthophore cell shape transition and density. Genetic analysis reveals a cell-autonomous requirement of gap junctions composed of Cx41.8 and Cx39.4 in xanthophores for their iridophore-dependent cell shape transition and increase in density in light-stripe regions. Initial melanophore-xanthophore interactions are independent of these gap junctions; however, subsequently they are also required to induce the acquisition of stellate shapes in xanthophores of the dark stripes. In summary, we conclude that, whereas homotypic interactions regulate xanthophore coverage in the skin, their cell shape transitions and density is regulated by gap junction-mediated, heterotypic interactions with iridophores and melanophores. PMID:27742608

  7. Emergence of Algal Blooms: The Effects of Short-Term Variability in Water Quality on Phytoplankton Abundance, Diversity, and Community Composition in a Tidal Estuary

    PubMed Central

    Egerton, Todd A.; Morse, Ryan E.; Marshall, Harold G.; Mulholland, Margaret R.

    2014-01-01

    Algal blooms are dynamic phenomena, often attributed to environmental parameters that vary on short timescales (e.g., hours to days). Phytoplankton monitoring programs are largely designed to examine long-term trends and interannual variability. In order to better understand and evaluate the relationships between water quality variables and the genesis of algal blooms, daily samples were collected over a 34 day period in the eutrophic Lafayette River, a tidal tributary within Chesapeake Bay’s estuarine complex, during spring 2006. During this period two distinct algal blooms occurred; the first was a cryptomonad bloom and this was followed by a bloom of the mixotrophic dinoflagellate, Gymnodinium instriatum. Chlorophyll a, nutrient concentrations, and physical and chemical parameters were measured daily along with phytoplankton abundance and community composition. While 65 phytoplankton species from eight major taxonomic groups were identified in samples and total micro- and nano-phytoplankton cell densities ranged from 5.8 × 106 to 7.8 × 107 cells L−1, during blooms, cryptomonads and G. instriatum were 91.6% and 99.0%, respectively, of the total phytoplankton biomass during blooms. The cryptomonad bloom developed following a period of rainfall and concomitant increases in inorganic nitrogen concentrations. Nitrate, nitrite and ammonium concentrations 0 to 5 days prior were positively lag-correlated with cryptomonad abundance. In contrast, the G. insriatum bloom developed during periods of low dissolved nitrogen concentrations and their abundance was negatively correlated with inorganic nitrogen concentrations. PMID:27694775

  8. Sixty years in algal physiology and photosynthesis.

    PubMed

    Pirson, A

    1994-06-01

    This personal perspective records research experiences in chemistry and biology at four German universities, two before and two after World War II. The research themes came from cytophysiology of green unicellular algae, in particular their photosynthesis. The function of inorganic ions in photosynthesis and dark respiration was investigated at different degrees of specific mineral stress (deficiencies), and the kinetics of recovery followed after the addition of the missing element. Two types of recovery of photosynthesis were observed: indirect restitution via growth processes and immediate normalisation. From the latter case (K(+), phosphate, Mn(++)) the effect of manganese was emphasized as its role in photosynthetic O2 evolution became established during our research. Other themes of our group, with some bearing on photosynthesis were: synchronization of cell growth by light-dark change and effects of blue (vs. red) light on the composition of green cells. Some experiences in connection with algal mass cultures are included. Discussion of several editorial projects shows how photosynthesis, as an orginally separated field of plant biochemistry and biophysics, became included into general cell physiology and even ecophysiology of green plants. The paper contains an appreciation of the authors' main mentor Kurt Noack (1888-1963) and of Ernst Georg Pringsheim (1881-1970), founder of experimental phycology.

  9. Enhanced Production of Green Tide Algal Biomass through Additional Carbon Supply

    PubMed Central

    de Paula Silva, Pedro H.; Paul, Nicholas A.; de Nys, Rocky; Mata, Leonardo

    2013-01-01

    Intensive algal cultivation usually requires a high flux of dissolved inorganic carbon (Ci) to support productivity, particularly for high density algal cultures. Carbon dioxide (CO2) enrichment can be used to overcome Ci limitation and enhance productivity of algae in intensive culture, however, it is unclear whether algal species with the ability to utilise bicarbonate (HCO3−) as a carbon source for photosynthesis will benefit from CO2 enrichment. This study quantified the HCO3− affinity of three green tide algal species, Cladophora coelothrix, Cladophora patentiramea and Chaetomorpha linum, targeted for biomass and bioenergy production. Subsequently, we quantified productivity and carbon, nitrogen and ash content in response to CO2 enrichment. All three species had similar high pH compensation points (9.7–9.9), and grew at similar rates up to pH 9, demonstrating HCO3− utilization. Algal cultures enriched with CO2 as a carbon source had 30% more total Ci available, supplying twenty five times more CO2 than the control. This higher Ci significantly enhanced the productivity of Cladophora coelothrix (26%), Chaetomorpha linum (24%) and to a lesser extent for Cladophora patentiramea (11%), compared to controls. We demonstrated that supplying carbon as CO2 can enhance the productivity of targeted green tide algal species under intensive culture, despite their clear ability to utilise HCO3−. PMID:24324672

  10. Enhanced production of green tide algal biomass through additional carbon supply.

    PubMed

    de Paula Silva, Pedro H; Paul, Nicholas A; de Nys, Rocky; Mata, Leonardo

    2013-01-01

    Intensive algal cultivation usually requires a high flux of dissolved inorganic carbon (Ci) to support productivity, particularly for high density algal cultures. Carbon dioxide (CO2) enrichment can be used to overcome Ci limitation and enhance productivity of algae in intensive culture, however, it is unclear whether algal species with the ability to utilise bicarbonate (HCO3 (-)) as a carbon source for photosynthesis will benefit from CO2 enrichment. This study quantified the HCO3 (-) affinity of three green tide algal species, Cladophora coelothrix, Cladophora patentiramea and Chaetomorpha linum, targeted for biomass and bioenergy production. Subsequently, we quantified productivity and carbon, nitrogen and ash content in response to CO2 enrichment. All three species had similar high pH compensation points (9.7-9.9), and grew at similar rates up to pH 9, demonstrating HCO3 (-) utilization. Algal cultures enriched with CO2 as a carbon source had 30% more total Ci available, supplying twenty five times more CO2 than the control. This higher Ci significantly enhanced the productivity of Cladophora coelothrix (26%), Chaetomorpha linum (24%) and to a lesser extent for Cladophora patentiramea (11%), compared to controls. We demonstrated that supplying carbon as CO2 can enhance the productivity of targeted green tide algal species under intensive culture, despite their clear ability to utilise HCO3 (-).

  11. Metabolic systems analysis to advance algal biotechnology.

    PubMed

    Schmidt, Brian J; Lin-Schmidt, Xiefan; Chamberlin, Austin; Salehi-Ashtiani, Kourosh; Papin, Jason A

    2010-07-01

    Algal fuel sources promise unsurpassed yields in a carbon neutral manner that minimizes resource competition between agriculture and fuel crops. Many challenges must be addressed before algal biofuels can be accepted as a component of the fossil fuel replacement strategy. One significant challenge is that the cost of algal fuel production must become competitive with existing fuel alternatives. Algal biofuel production presents the opportunity to fine-tune microbial metabolic machinery for an optimal blend of biomass constituents and desired fuel molecules. Genome-scale model-driven algal metabolic design promises to facilitate both goals by directing the utilization of metabolites in the complex, interconnected metabolic networks to optimize production of the compounds of interest. Network analysis can direct microbial development efforts towards successful strategies and enable quantitative fine-tuning of the network for optimal product yields while maintaining the robustness of the production microbe. Metabolic modeling yields insights into microbial function, guides experiments by generating testable hypotheses, and enables the refinement of knowledge on the specific organism. While the application of such analytical approaches to algal systems is limited to date, metabolic network analysis can improve understanding of algal metabolic systems and play an important role in expediting the adoption of new biofuel technologies.

  12. High power density fuel cell comprising an array of microchannels

    DOEpatents

    Morse, Jeffrey D.; Upadhye, Ravindra S.; Spadaccini, Christopher M.; Park, Hyung Gyu

    2013-10-15

    A fuel cell according to one embodiment includes a porous electrolyte support structure defining an array of microchannels, the microchannels including fuel and oxidant microchannels; fuel electrodes formed along some of the microchannels; and oxidant electrodes formed along other of the microchannels. A method of making a fuel cell according to one embodiment includes forming an array of walls defining microchannels therebetween using at least one of molding, stamping, extrusion, injection and electrodeposition; processing the walls to make the walls porous, thereby creating a porous electrolyte support structure; forming anode electrodes along some of the microchannels; and forming cathode electrodes along other of the microchannels. Additional embodiments are also disclosed.

  13. Cell density in prostate histopathology images as a measure of tumor distribution

    NASA Astrophysics Data System (ADS)

    Reynolds, Hayley M.; Williams, Scott; Zhang, Alan M.; Ong, Cheng Soon; Rawlinson, David; Chakravorty, Rajib; Mitchell, Catherine; Haworth, Annette

    2014-03-01

    We have developed an automatic technique to measure cell density in high resolution histopathology images of the prostate, allowing for quantification of differences between tumour and benign regions of tissue. Haemotoxylin and Eosin (H&E) stained histopathology slides from five patients were scanned at 20x magnification and annotated by an expert pathologist. Colour deconvolution and a radial symmetry transform were used to detect cell nuclei in the images, which were processed as a set of small tiles and combined to produce global maps of cell density. Kolmogorov-Smirnov tests showed a significant difference in cell density distribution between tumour and benign regions of tissue for all images analyzed (p < 0.05), suggesting that cell density may be a useful feature for segmenting tumour in un-annotated histopathology images. ROC curves quantified the potential utility of cell density measurements in terms of specificity and sensitivity and threshold values were investigated for their classification accuracy. Motivation for this work derives from a larger study in which we aim to correlate ground truth histopathology with in-vivo multiparametric MRI (mpMRI) to validate tumour location and tumour characteristics. Specifically, cell density maps will be registered with T2-weighted MRI and ADC maps from diffusion-weighted MRI. The validated mpMRI data will then be used to parameterise a radiobiological model for designing focal radiotherapy treatment plans for prostate cancer patients.

  14. Low density cell culture of locust neurons in closed-channel microfluidic devices.

    PubMed

    Göbbels, Katrin; Thiebes, Anja Lena; van Ooyen, André; Schnakenberg, Uwe; Bräunig, Peter

    2010-08-01

    Microfluidic channel systems were fabricated out of polydimethylsiloxane (PDMS) and used as culture vessels for primary culture of neurons from locust thoracic ganglia. In a biocompatibility study it was shown that cell adhesion and neuronal cell growth of locust neurons on uncoated PDMS was restricted. Coating with concanavalin A improved cell adhesion. In closed-channel microfluidic devices neurons were grown in static-bath culture conditions for more than 15 days. Cell densities of up to 20 cells/channel were not exceeded in low-density cultures but we also found optimal cell growth of single neurons inside individual channels. The first successful cultivation of insect neurons in closed-channel microfluidic devices provides a prerequisite for the development of low density neuronal networks on multi electrode arrays combined with microfluidic devices.

  15. Expression of the Coxsackievirus and Adenovirus Receptor in Cultured Human Umbilical Vein Endothelial Cells: Regulation in Response to Cell Density

    PubMed Central

    Carson, Steven D.; Hobbs, Justin T.; Tracy, Steven M.; Chapman, Nora M.

    1999-01-01

    Primary cultures of human umbilical vein endothelial cells (HUVEC) express the human coxsackievirus and adenovirus receptor (HCAR). Whereas HCAR expression in HeLa cells was constant with respect to cell density, HCAR expression in HUVEC increased with culture confluence. HCAR expression in HUVEC was not quantitatively altered by infection with coxsackievirus B. PMID:10400813

  16. Didymosphenia geminata: Algal blooms in oligotrophic streams and rivers

    NASA Astrophysics Data System (ADS)

    Sundareshwar, P. V.; Upadhayay, S.; Abessa, M.; Honomichl, S.; Berdanier, B.; Spaulding, S. A.; Sandvik, C.; Trennepohl, A.

    2011-05-01

    In recent decades, the diatom Didymosphenia geminata has emerged as nuisance species in river systems around the world. This periphytic alga forms large “blooms” in temperate streams, presenting a counterintuitive result: the blooms occur primarily in oligotrophic streams and rivers, where phosphorus (P) availability typically limits primary production. The goal of this study is to examine how high algal biomass is formed under low P conditions. We reveal a biogeochemical process by which D. geminata mats concentrate P from flowing waters. First, the mucopolysaccaride stalks of D. geminata adsorb both iron (Fe) and P. Second, enzymatic and bacterial processes interact with Fe to increase the biological availability of P. We propose that a positive feedback between total stalk biomass and high growth rate is created, which results in abundant P for cell division. The affinity of stalks for Fe in association with iron-phosphorus biogeochemistry suggest a resolution to the paradox of algal blooms in oliogotrophic streams and rivers.

  17. Study of cnidarian-algal symbiosis in the "omics" age.

    PubMed

    Meyer, Eli; Weis, Virginia M

    2012-08-01

    The symbiotic associations between cnidarians and dinoflagellate algae (Symbiodinium) support productive and diverse ecosystems in coral reefs. Many aspects of this association, including the mechanistic basis of host-symbiont recognition and metabolic interaction, remain poorly understood. The first completed genome sequence for a symbiotic anthozoan is now available (the coral Acropora digitifera), and extensive expressed sequence tag resources are available for a variety of other symbiotic corals and anemones. These resources make it possible to profile gene expression, protein abundance, and protein localization associated with the symbiotic state. Here we review the history of "omics" studies of cnidarian-algal symbiosis and the current availability of sequence resources for corals and anemones, identifying genes putatively involved in symbiosis across 10 anthozoan species. The public availability of candidate symbiosis-associated genes leaves the field of cnidarian-algal symbiosis poised for in-depth comparative studies of sequence diversity and gene expression and for targeted functional studies of genes associated with symbiosis. Reviewing the progress to date suggests directions for future investigations of cnidarian-algal symbiosis that include (i) sequencing of Symbiodinium, (ii) proteomic analysis of the symbiosome membrane complex, (iii) glycomic analysis of Symbiodinium cell surfaces, and (iv) expression profiling of the gastrodermal cells hosting Symbiodinium.

  18. Micro-structured surfaces for algal biofilm growth

    NASA Astrophysics Data System (ADS)

    Sathananthan, Suthamathy; Genin, Scott N.; Aitchison, J. Stewart; Allen, D. Grant

    2013-12-01

    It is well known that cells respond to structured surface cues that are on the micro/nanometer scale. Tissue engineering and bio-fouling fields have utilized the semiconductor device fabrication processes to make micro- and nanometer patterned surfaces to study animal cell tissue formation and to prevent algae attachment on marine surfaces respectively. In this paper we describe the use of micro-structured surfaces to study the attachment and growth of algal films. This paper gives an overview of how micro-structured surfaces are made for this purpose, how they are incorporated into a photo bioreactor and how this patterning influences the growth of an algal biofilm. Our results suggest that surface patterning with deeper V-groove patterns that are of the same size scale as the algal species has resulted in higher biomass productivity giving them a chance to embed and attach on the slope and flat surfaces whereas shallower size grooves and completely flat surfaces did not show this trend.

  19. Discrimination Between Lung Homeostatic and Injury-Induced Epithelial Progenitor Subsets by Cell-Density Properties

    PubMed Central

    Sen, Namita; Weprin, Samuel

    2013-01-01

    Stem/progenitor cells and their lineage derivatives are often identified by patterns and intensity of cell clusters of differentiation presentation. However, the cell biochemical façade can prove to be elusive, transient, and subject to interlaboratory disparities. To enhance current methods of lung stem cell isolation and identification and to investigate biophysical changes, which occur during homeostasis and in response to acute lung injury, we separated cells on a discontinuous density gradient, of 1.025–1.074 g/cm3, and characterized the eluted lineages. At homeostasis, surfactant protein-C (SFTPC)-expressing cells of the alveolar type (AT)-2 lineage possessed average densities ≥1.039 g/cm3 and aquaporin-5 producing AT1 cells equilibrated at densities <1.039 g/cm3. While 0.74%±0.32% of lung cells were determined proliferating or postmitotic by BrdU nucleotide uptake, 73% of CD49f-, 72% of c-KIT-, and 61% of SCA-1-positive cells (putative alveolar progenitor lineage markers) showed densities ≤1.039 g/cm3. CD49f/EpCAMhi progenitors, as well as c-KITpos/CD45neg cells, could be enriched at the 1.039 g/cm3 interface. Following acute bleomycin-induced injury, the frequency of BrdU-incorporating cells rose to 0.92%±0.36% and density could largely explain cell-lineage distribution. Specifically, a decline in the density of mitotic/postmitotic SFTPC-positive cells to ≤1.029 g/cm3, in conjunction with an increase in CD45-positive, and proliferating CD45 and c-KIT cells in the heaviest fraction (≥1.074 g/cm3) were observed. These data attest to the generation of AT2 cells from low-density precursors and emphasize a relationship between cell density and molecular expression following injury, expanding on our current understanding of lung and progenitor cell dynamics. PMID:23461422

  20. Discrimination between lung homeostatic and injury-induced epithelial progenitor subsets by cell-density properties.

    PubMed

    Sen, Namita; Weprin, Samuel; Peter, Yakov

    2013-07-15

    Stem/progenitor cells and their lineage derivatives are often identified by patterns and intensity of cell clusters of differentiation presentation. However, the cell biochemical façade can prove to be elusive, transient, and subject to interlaboratory disparities. To enhance current methods of lung stem cell isolation and identification and to investigate biophysical changes, which occur during homeostasis and in response to acute lung injury, we separated cells on a discontinuous density gradient, of 1.025-1.074 g/cm(3), and characterized the eluted lineages. At homeostasis, surfactant protein-C (SFTPC)-expressing cells of the alveolar type (AT)-2 lineage possessed average densities ≥1.039 g/cm(3) and aquaporin-5 producing AT1 cells equilibrated at densities <1.039 g/cm(3). While 0.74%±0.32% of lung cells were determined proliferating or postmitotic by BrdU nucleotide uptake, 73% of CD49f-, 72% of c-KIT-, and 61% of SCA-1-positive cells (putative alveolar progenitor lineage markers) showed densities ≤1.039 g/cm(3). CD49f/EpCAM(hi) progenitors, as well as c-KIT(pos)/CD45(neg) cells, could be enriched at the 1.039 g/cm(3) interface. Following acute bleomycin-induced injury, the frequency of BrdU-incorporating cells rose to 0.92%±0.36% and density could largely explain cell-lineage distribution. Specifically, a decline in the density of mitotic/postmitotic SFTPC-positive cells to ≤1.029 g/cm(3), in conjunction with an increase in CD45-positive, and proliferating CD45 and c-KIT cells in the heaviest fraction (≥1.074 g/cm(3)) were observed. These data attest to the generation of AT2 cells from low-density precursors and emphasize a relationship between cell density and molecular expression following injury, expanding on our current understanding of lung and progenitor cell dynamics.

  1. Cell density and actomyosin contractility control the organization of migrating collectives within an epithelium

    PubMed Central

    Loza, Andrew J.; Koride, Sarita; Schimizzi, Gregory V.; Li, Bo; Sun, Sean X.; Longmore, Gregory D.

    2016-01-01

    The mechanisms underlying collective migration are important for understanding development, wound healing, and tumor invasion. Here we focus on cell density to determine its role in collective migration. Our findings show that increasing cell density, as might be seen in cancer, transforms groups from broad collectives to small, narrow streams. Conversely, diminishing cell density, as might occur at a wound front, leads to large, broad collectives with a distinct leader–follower structure. Simulations identify force-sensitive contractility as a mediator of how density affects collectives, and guided by this prediction, we find that the baseline state of contractility can enhance or reduce organization. Finally, we test predictions from these data in an in vivo epithelium by using genetic manipulations to drive collective motion between predicted migratory phases. This work demonstrates how commonly altered cellular properties can prime groups of cells to adopt migration patterns that may be harnessed in health or exploited in disease. PMID:27605707

  2. Cell density and actomyosin contractility control the organization of migrating collectives within an epithelium.

    PubMed

    Loza, Andrew J; Koride, Sarita; Schimizzi, Gregory V; Li, Bo; Sun, Sean X; Longmore, Gregory D

    2016-11-07

    The mechanisms underlying collective migration are important for understanding development, wound healing, and tumor invasion. Here we focus on cell density to determine its role in collective migration. Our findings show that increasing cell density, as might be seen in cancer, transforms groups from broad collectives to small, narrow streams. Conversely, diminishing cell density, as might occur at a wound front, leads to large, broad collectives with a distinct leader-follower structure. Simulations identify force-sensitive contractility as a mediator of how density affects collectives, and guided by this prediction, we find that the baseline state of contractility can enhance or reduce organization. Finally, we test predictions from these data in an in vivo epithelium by using genetic manipulations to drive collective motion between predicted migratory phases. This work demonstrates how commonly altered cellular properties can prime groups of cells to adopt migration patterns that may be harnessed in health or exploited in disease.

  3. Effects of ozone and peroxone on algal separation via dispersed air flotation.

    PubMed

    Nguyen, Truc Linh; Lee, D J; Chang, J S; Liu, J C

    2013-05-01

    Effects of pre-oxidation on algal separation by dispersed air flotation were examined. Ozone (O3) and peroxone (O3 and H2O2) could induce cell lysis, release of intracellular organic matter (IOM), and mineralization of organic substances. Separation efficiency of algal cells improved when pre-oxidized. Total of 76.4% algal cells was separated at 40 mg/L of N-cetyl-N-N-N-trimethylammonium bromide (CTAB), while 95% were separated after 30-min ozonation. Pre-oxidation by ozone and peroxone also enhanced flotation separation efficiency of dissolved organic carbon (DOC), polysaccharide, and protein, in which peroxone process exerted more significantly than O3. Two main mechanisms were involved in flotation separation of unoxidized algal suspension, namely hydrophobic cell surface and cell flocculation resulting from CTAB adsorption. However, flocculation by CTAB was hindered for pre-oxidized algal suspensions. It implied that the compositional changes in extracellular organic matter (EOM) by pre-oxidation were more determined for flotation separation of pre-oxidized cells.

  4. Sustainable Algal Energy Production and Environmental Remediation

    SciTech Connect

    Cooke, William E.

    2012-07-14

    Overall, our results confirm that wild algal species sequester a wide range of organic and metal contaminants and excess nutrients (PAHs, trace metals, and nutrients) from natural waters, and suggest parameters that could be useful in predicting uptake rates for algae growing on an algal floway or other algal growth systems in the environment or in industrial processes. The implication for various fuel production processes differ with the detailed unit operations involved, and these results will be of use in the developing of scaling experiments for various types of engineering process designs.

  5. Exploring the Utilization of Complex Algal Communities to Address Algal Pond Crash and Increase Annual Biomass Production for Algal Biofuels

    SciTech Connect

    Hamilton, Cyd E.

    2014-03-25

    This white paper briefly reviews the research literature exploring complex algal communities as a means of increasing algal biomass production via increased tolerance, resilience, and resistance to a variety of abiotic and biotic perturbations occurring within harvesting timescales. This paper identifies what data are available and whether more research utilizing complex communities is needed to explore the potential of complex algal community stability (CACS) approach as a plausible means to increase biomass yields regardless of ecological context and resulting in decreased algal-based fuel prices by reducing operations costs. By reviewing the literature for what we do and do not know, in terms of CACS methodologies, this report will provide guidance for future research addressing pond crash phenomena.

  6. High power density fuel cell comprising an array of microchannels

    DOEpatents

    Sopchak, David A; Morse, Jeffrey D; Upadhye, Ravindra S; Kotovsky, Jack; Graff, Robert T

    2014-05-06

    A phosphoric acid fuel cell according to one embodiment includes an array of microchannels defined by a porous electrolyte support structure extending between bottom and upper support layers, the microchannels including fuel and oxidant microchannels; fuel electrodes formed along some of the microchannels; and air electrodes formed along other of the microchannels. A method of making a phosphoric acid fuel cell according to one embodiment includes etching an array of microchannels in a substrate, thereby forming walls between the microchannels; processing the walls to make the walls porous, thereby forming a porous electrolyte support structure; forming anode electrodes along some of the walls; forming cathode electrodes along other of the walls; and filling the porous electrolyte support structure with a phosphoric acid electrolyte. Additional embodiments are also disclosed.

  7. Gene Expression Profiles of Human Adipose Tissue-Derived Mesenchymal Stem Cells Are Modified by Cell Culture Density

    PubMed Central

    Yoo, Keon Hee; Lee, Tae-Hee; Kim, Hye Jin; Jang, In Keun; Chun, Yong Hoon; Kim, Hyung Joon; Park, Seung Jo; Lee, Soo Hyun; Son, Meong Hi; Jung, Hye Lim; Sung, Ki Woong; Koo, Hong Hoe

    2014-01-01

    Previous studies conducted cell expansion ex vivo using low initial plating densities for optimal expansion and subsequent differentiation of mesenchymal stem cells (MSCs). However, MSC populations are heterogeneous and culture conditions can affect the characteristics of MSCs. In this study, differences in gene expression profiles of adipose tissue (AT)-derived MSCs were examined after harvesting cells cultured at different densities. AT-MSCs from three different donors were plated at a density of 200 or 5,000 cells/cm2. After 7 days in culture, detailed gene expression profiles were investigated using a DNA chip microarray, and subsequently validated using a reverse transcription polymerase chain reaction (RT-PCR) analysis. Gene expression profiles were influenced primarily by the level of cell confluence at harvest. In MSCs harvested at ∼90% confluence, 177 genes were up-regulated and 102 genes down-regulated relative to cells harvested at ∼50% confluence (P<0.05, FC>2). Proliferation-related genes were highly expressed in MSCs harvested at low density, while genes that were highly expressed in MSCs harvested at high density (∼90% confluent) were linked to immunity and defense, cell communication, signal transduction and cell motility. Several cytokine, chemokine and growth factor genes involved in immunosuppression, migration, and reconstitution of damaged tissues were up-regulated in MSCs harvested at high density compared with MSCs harvested at low density. These results imply that cell density at harvest is a critical factor for modulating the specific gene-expression patterns of heterogeneous MSCs. PMID:24400072

  8. Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations.

    PubMed

    Wang, Tuo; Yang, Hui; Kubicki, James D; Hong, Mei

    2016-06-13

    The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D (13)C-(13)C correlation spectra of uniformly (13)C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose (13)C chemical shifts differ significantly from the (13)C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing, and hydrogen bonding from celluloses of other organisms. 2D (13)C-(13)C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Celluloses f and g are well mixed chains on the microfibril surface, celluloses a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of

  9. Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations

    PubMed Central

    Wang, Tuo; Yang, Hui; Kubicki, James D.; Hong, Mei

    2017-01-01

    The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D 13C-13C correlation spectra of uniformly 13C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose 13C chemical shifts differ significantly from the 13C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing and hydrogen bonding from celluloses of other organisms. 2D 13C-13C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Cellulose f and g are well mixed chains on the microfibril surface, cellulose a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of bacterial, algal

  10. Bone Density Loss Is Associated With Blood Cell Counts.

    PubMed

    Valderrábano, Rodrigo J; Lui, Li-Yung; Lee, Jennifer; Cummings, Steven R; Orwoll, Eric S; Hoffman, Andrew R; Wu, Joy Y

    2017-02-01

    Hematopoiesis depends on a supportive microenvironment. Preclinical studies in mice have demonstrated that osteoblasts influence the development of blood cells, particularly erythrocytes, B lymphocytes, and neutrophils. However, it is unknown whether osteoblast numbers or function impact blood cell counts in humans. We tested the hypothesis that men with low BMD or greater BMD loss have decreased circulating erythrocytes and lymphocytes and increased myeloid cells. We performed a cross-sectional analysis and prospective analysis in the Osteoporotic Fractures in Men (MrOS) study, a multisite longitudinal cohort study. A total of 2571 community-dwelling men (≥65 years) who were able to walk without assistance, did not have a hip replacement or fracture, and had complete blood counts (CBCs) at the third study visit were analyzed. Multivariable (MV)-adjusted logistic regression estimated odds of white blood cell (WBC) subtypes (highest and lowest quintile versus middle), and anemia (clinically defined) associated with BMD by DXA scan (at visit 3), annualized percent BMD change (baseline to visit 3), and high BMD loss (>0.5%/year, from baseline to visit 3) at the femoral neck (FN) and total hip (TH). MV-adjusted models included age, BMI, cancer history, smoking status, alcohol intake, corticosteroid use, self-reported health, thiazide use, and physical activity. At visit 3 greater TH BMD loss (per 1 SD) was associated with increased odds of anemia, high neutrophils, and low lymphocytes. Annualized BMD loss of >0.5% was associated with increased odds of anemia, high neutrophils, and low lymphocytes. Similar results were observed for FN BMD regarding anemia and lymphocytes. We conclude that community-dwelling older men with declining hip BMD over about 7 years had increased risks of anemia, lower lymphocyte count, and higher neutrophil count, consistent with preclinical studies. Bone health and hematopoiesis may have greater interdependency than previously recognized.

  11. Control of neural stem cell adhesion and density by an electronic polymer surface switch.

    PubMed

    Saltó, Carmen; Saindon, Emilien; Bolin, Maria; Kanciurzewska, Anna; Fahlman, Mats; Jager, Edwin W H; Tengvall, Pentti; Arenas, Ernest; Berggren, Magnus

    2008-12-16

    Adhesion is an essential parameter for stem cells. It regulates the overall cell density along the carrying surface, which further dictates the differentiation scheme of stem cells toward a more matured and specified population as well as tissue. Electronic control of the seeding density of neural stem cells (c17.2) is here reported. Thin electrode films of poly(3,4-ethylenedioxythiophene) (PEDOT):Tosylate were manufactured along the floor of cell growth dishes. As the oxidation state of the conjugated polymer electrodes was controlled, the seeding density could be varied by a factor of 2. Along the oxidized PEDOT:Tosylate-electrodes, a relatively lower density of, and less tightly bonded, human serum albumin (HSA) was observed as compared to reduced electrodes. We found that this favors adhesion of the specific stem cells studied. Surface analysis experiments, such as photoelectron spectroscopy, and water contact angle measurements, were carried out to investigate the mechanisms responsible for the electronic control of the seeding density of the c17.2 neural stem cells. Further, our findings may provide an opening for electronic control of stem cell differentiation.

  12. Current progress in high cell density yeast bioprocesses for bioethanol production.

    PubMed

    Westman, Johan O; Franzén, Carl Johan

    2015-08-01

    High capital costs and low reaction rates are major challenges for establishment of fermentation-based production systems in the bioeconomy. Using high cell density cultures is an efficient way to increase the volumetric productivity of fermentation processes, thereby enabling faster and more robust processes and use of smaller reactors. In this review, we summarize recent progress in the application of high cell density yeast bioprocesses for first and second generation bioethanol production. High biomass concentrations obtained by retention of yeast cells in the reactor enables easier cell reuse, simplified product recovery and higher dilution rates in continuous processes. High local cell density cultures, in the form of encapsulated or strongly flocculating yeast, furthermore obtain increased tolerance to convertible fermentation inhibitors and utilize glucose and other sugars simultaneously, thereby overcoming two additional hurdles for second generation bioethanol production. These effects are caused by local concentration gradients due to diffusion limitations and conversion of inhibitors and sugars by the cells, which lead to low local concentrations of inhibitors and glucose. Quorum sensing may also contribute to the increased stress tolerance. Recent developments indicate that high cell density methodology, with emphasis on high local cell density, offers significant advantages for sustainable second generation bioethanol production.

  13. Anion-Intercalating Cathodes for High-Energy-Density Cells

    NASA Technical Reports Server (NTRS)

    West, William

    2006-01-01

    A report discusses physicochemical issues affecting a fluoride-intercalating cathode that operates in conjunction with a lithium ion-intercalating anode in a rechargeable electrochemical cell described in a cited prior report. The instant report also discusses corresponding innovations made in solvent and electrolyte compositions since the prior report. The advantages of this cell, relative to other lithium-ion-based cells, are said to be greater potential (5 V vs. 4 V), and greater theoretical cathode specific capacity (0.9 to 2.2 A-h/g vs. about 0.18 A-h/g). The discussion addresses a need for the solvent to be unreactive toward the lithium anode and to resist anodic oxidation at potentials greater than about 4.5 V vs. lithium; the pertinent innovation is the selection of propylene carbonate (PC) as a solvent having significantly more stability, relative to other solvents that have been tried. The discussion also addresses the need for an electrolyte additive, denoted an anion receptor, to complex the fluoride ion; the pertinent innovation is the selection of tris(hexafluoroisopropyl) borate as a superior alternative to the prior anion receptor, which was tris(pentafluorophenyl) borate.

  14. Cell density signal protein suitable for treatment of connective tissue injuries and defects

    DOEpatents

    Schwarz, Richard I.

    2002-08-13

    Identification, isolation and partial sequencing of a cell density protein produced by fibroblastic cells. The cell density signal protein comprising a 14 amino acid peptide or a fragment, variant, mutant or analog thereof, the deduced cDNA sequence from the 14 amino acid peptide, a recombinant protein, protein and peptide-specific antibodies, and the use of the peptide and peptide-specific antibodies as therapeutic agents for regulation of cell differentiation and proliferation. A method for treatment and repair of connective tissue and tendon injuries, collagen deficiency, and connective tissue defects.

  15. Cell seeding density is a critical determinant for copolymer scaffolds‐induced bone regeneration

    PubMed Central

    Leknes, Knut N.; Pedersen, Torbjorn O.; Xing, Zhe; Sun, Yang; Lie, Stein A.; Finne‐Wistrand, Anna; Mustafa, Kamal

    2015-01-01

    Abstract Constructs intended for bone tissue engineering (TE) are influenced by the initial cell seeding density. Therefore, the objective of this study was to determine the effect of bone marrow stromal stem cells (BMSCs) density loaded onto copolymer scaffolds on bone regeneration. BMSCs were harvested from rat's bone marrow and cultured in media with or without osteogenic supplements. Cells were seeded onto poly(l‐lactide‐co‐ε‐caprolactone) [poly(LLA‐co‐CL)] scaffolds at two different densities: low density (1 × 106 cells/scaffold) or high density (2 × 106 cells/scaffold) using spinner modified flasks and examined after 1 and 3 weeks. Initial attachment and spread of BMSC onto the scaffolds was recorded by scanning electron microscopy. Cell proliferation was assessed by DNA quantification and cell differentiation by quantitative real‐time reverse transcriptase‐polymerized chain reaction analysis (qRT‐PCR). Five‐millimeter rat calvarial defects (24 defects in 12 rats) were implanted with scaffolds seeded with either low or high density expanded with or without osteogenic supplements. Osteogenic supplements significantly increased cell proliferation (p < 0.001). Scaffolds seeded at high cell density exhibited higher mRNA expressions of Runx2 p = 0.001, Col1 p = 0.001, BMP2 p < 0.001, BSP p < 0.001, and OC p = 0.013. More bone was formed in response to high cell seeding density (p = 0.023) and high seeding density with osteogenic medium (p = 0.038). Poly (LLA‐co‐CL) scaffolds could be appropriate candidates for bone TE. The optimal number of cells to be loaded onto scaffolds is critical for promoting Extracellular matrix synthesis and bone formation. Cell seeding density and osteogenic supplements may have a synergistic effect on the induction of new bone. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 3649–3658, 2015. PMID:26013960

  16. Ganglion cell and displaced amacrine cell density distribution in the retina of the howler monkey (Alouatta caraya).

    PubMed

    Muniz, José Augusto Pereira Carneiro; de Athaide, Luana Modesto; Gomes, Bruno Duarte; Finlay, Barbara L; Silveira, Luiz Carlos de Lima

    2014-01-01

    Unlike all other New World (platyrrine) monkeys, both male and female howler monkeys (Alouatta sp.) are obligatory trichromats. In all other platyrrines, only females can be trichromats, while males are always dichromats, as determined by multiple behavioral, electrophysiological, and genetic studies. In addition to obligatory trichromacy, Alouatta has an unusual fovea, with substantially higher peak cone density in the foveal pit than every other diurnal anthropoid monkey (both platyrrhines and catarrhines) and great ape yet examined, including humans. In addition to documenting the general organization of the retinal ganglion cell layer in Alouatta, the distribution of cones is compared to retinal ganglion cells, to explore possible relationships between their atypical trichromacy and foveal specialization. The number and distribution of retinal ganglion cells and displaced amacrine cells were determined in six flat-mounted retinas from five Alouatta caraya. Ganglion cell density peaked at 0.5 mm between the fovea and optic nerve head, reaching 40,700-45,200 cells/mm2. Displaced amacrine cell density distribution peaked between 0.5-1.75 mm from the fovea, reaching mean values between 2,050-3,100 cells/mm2. The mean number of ganglion cells was 1,133,000±79,000 cells and the mean number of displaced amacrine cells was 537,000±61,800 cells, in retinas of mean area 641±62 mm2. Ganglion cell and displaced amacrine cell density distribution in the Alouatta retina was consistent with that observed among several species of diurnal Anthropoidea, both platyrrhines and catarrhines. The principal alteration in the Alouatta retina appears not to be in the number of any retinal cell class, but rather a marked gradient in cone density within the fovea, which could potentially support high chromatic acuity in a restricted central region.

  17. Ganglion Cell and Displaced Amacrine Cell Density Distribution in the Retina of the Howler Monkey (Alouatta caraya)

    PubMed Central

    Muniz, José Augusto Pereira Carneiro; de Athaide, Luana Modesto; Gomes, Bruno Duarte; Finlay, Barbara L.; Silveira, Luiz Carlos de Lima

    2014-01-01

    Unlike all other New World (platyrrine) monkeys, both male and female howler monkeys (Alouatta sp.) are obligatory trichromats. In all other platyrrines, only females can be trichromats, while males are always dichromats, as determined by multiple behavioral, electrophysiological, and genetic studies. In addition to obligatory trichromacy, Alouatta has an unusual fovea, with substantially higher peak cone density in the foveal pit than every other diurnal anthropoid monkey (both platyrrhines and catarrhines) and great ape yet examined, including humans. In addition to documenting the general organization of the retinal ganglion cell layer in Alouatta, the distribution of cones is compared to retinal ganglion cells, to explore possible relationships between their atypical trichromacy and foveal specialization. The number and distribution of retinal ganglion cells and displaced amacrine cells were determined in six flat-mounted retinas from five Alouatta caraya. Ganglion cell density peaked at 0.5 mm between the fovea and optic nerve head, reaching 40,700–45,200 cells/mm2. Displaced amacrine cell density distribution peaked between 0.5–1.75 mm from the fovea, reaching mean values between 2,050–3,100 cells/mm2. The mean number of ganglion cells was 1,133,000±79,000 cells and the mean number of displaced amacrine cells was 537,000±61,800 cells, in retinas of mean area 641±62 mm2. Ganglion cell and displaced amacrine cell density distribution in the Alouatta retina was consistent with that observed among several species of diurnal Anthropoidea, both platyrrhines and catarrhines. The principal alteration in the Alouatta retina appears not to be in the number of any retinal cell class, but rather a marked gradient in cone density within the fovea, which could potentially support high chromatic acuity in a restricted central region. PMID:25546077

  18. Effects of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell counts.

    PubMed

    Gao, Feng; Lin, Tao; Pan, Yingzhe

    2016-09-01

    Diabetic keratopathy is an ocular complication that occurs with diabetes. In the present study, the effect of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell count was investigated. One hundred and eighty diabetic patients (360 eyes) were enrolled in the study during the period from March, 2012 to March, 2013. The patients were divided into three age groups: <5, 5-10 and >10 years, with 60 patients per group (120 eyes). During the same period, 60 healthy cases (120 eyes) were selected and labeled as the normal control group. The Pentacam was used to measure the corneal optical density, and central corneal thickness. Specular microscopy was used to examine the corneal endothelial cell density. The coefficient of partial correlation was used to control age and correlate the analysis between the corneal optical density, corneal endothelial cell density, and central corneal thickness. The stage of the disease, the medial and intimal corneal optical density and central corneal thickness was analyzed in the diabetes group. The corneal optical density in the diabetes group increased compared with that of the normal control group. The medial and intimal corneal optical density and central corneal thickness were positively correlated with the course of the disease. However, the corneal endothelial cell density was not associated with the course of diabetes. There was a positive association between the medial and intimal corneal optical density and central corneal thickness of the diabetic patients. In conclusion, the results of the present study show that medial and intimal corneal optical density and central corneal thickness were sensitive indicators for early diabetic keratopathy.

  19. Effects of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell counts

    PubMed Central

    Gao, Feng; Lin, Tao; Pan, Yingzhe

    2016-01-01

    Diabetic keratopathy is an ocular complication that occurs with diabetes. In the present study, the effect of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell count was investigated. One hundred and eighty diabetic patients (360 eyes) were enrolled in the study during the period from March, 2012 to March, 2013. The patients were divided into three age groups: <5, 5–10 and >10 years, with 60 patients per group (120 eyes). During the same period, 60 healthy cases (120 eyes) were selected and labeled as the normal control group. The Pentacam was used to measure the corneal optical density, and central corneal thickness. Specular microscopy was used to examine the corneal endothelial cell density. The coefficient of partial correlation was used to control age and correlate the analysis between the corneal optical density, corneal endothelial cell density, and central corneal thickness. The stage of the disease, the medial and intimal corneal optical density and central corneal thickness was analyzed in the diabetes group. The corneal optical density in the diabetes group increased compared with that of the normal control group. The medial and intimal corneal optical density and central corneal thickness were positively correlated with the course of the disease. However, the corneal endothelial cell density was not associated with the course of diabetes. There was a positive association between the medial and intimal corneal optical density and central corneal thickness of the diabetic patients. In conclusion, the results of the present study show that medial and intimal corneal optical density and central corneal thickness were sensitive indicators for early diabetic keratopathy. PMID:27588090

  20. Development of a rotating algal biofilm growth system for attached microalgae growth with in situ biomass harvest.

    PubMed

    Gross, Martin; Henry, Wesley; Michael, Clayton; Wen, Zhiyou

    2013-12-01

    This work aimed to develop a rotating algal biofilm (RAB) cultivation system that can be widely adopted by microalgae producers for easy biomass harvest. Algal cells were grown on the surface of a material rotating between nutrient-rich liquid and CO2-rich gaseous phase. Scrapping biomass from the attached surface avoided the expensive harvest operations such as centrifugation. Among various attachment materials, cotton sheet resulted in best algal growth, durability, and cost effectiveness. A lab-scale RAB system was further optimized with harvest frequency, rotation speed, and CO2 levels. The algal biomass from the RAB system had a similar water content as that in centrifuged biomass. An open pond raceway retrofitted with a pilot-scale RAB system resulted in a much higher biomass productivity when compared to a control open pond. Collectively, the research shows that the RAB system is an efficient algal culture system for easy biomass harvest with enhanced biomass productivity.

  1. Yearlong evaluation of performance and durability of a pilot-scale Revolving Algal Biofilm (RAB) cultivation system.

    PubMed

    Gross, Martin; Wen, Zhiyou

    2014-11-01

    Current algal cultivation has been mainly performed in open ponds or photobioreactors in which algal cells are suspended and harvested through flocculation and centrifugation. A unique attachment based Revolving Algal Biofilm (RAB) cultivation system was recently developed for easy biomass harvest with enhanced biomass productivity. The objective of this research was to evaluate the performance (durability, algal growth, and the geometry) of the RAB system at pilot-scale. A yearlong test of the RAB system was successfully conducted at a greenhouse facility at Boone, Iowa, USA. The RAB resulted in an average of 302% increase in biomass productivity compared to a standard raceway pond, with a maximum biomass productivity (ash free) of 18.9 g/m(2)-day being achieved. The RAB with a vertical configuration generated higher productivity than the triangular RAB. Collectively, the research shows that the RAB as an efficient algal culture system has great potential for being deployed at commercial scale.

  2. Influence of the Dislocation Density on the Performance of Heteroepitaxial Indium Phosphide Solar Cells

    NASA Technical Reports Server (NTRS)

    Jain, R. K.; Flood, D. J.

    1991-01-01

    Calculations are made to study the dependence of heteroepitaxial InP solar-cell efficiency on dislocation density. Effects of surface recombination velocity and cell emitter thickness are considered. Calculated results are compared with the available experimental results on representative InP solar cells. It is shown that heteroepitaxial InP cells with over 20 percent AM0 efficiency could be fabricated if dislocations are reduced to less than 100,000/sq cm.

  3. LIF Density Measurement Calibration Using a Reference Cell

    NASA Technical Reports Server (NTRS)

    Domonkos, Matthew T.; Williams, George J., Jr.; Lyons, Valerie J. (Technical Monitor)

    2002-01-01

    Flight qualification of ion thrusters typically requires testing on the order of 10,000 hours. Extensive knowledge of wear mechanisms and rates is necessary to establish design confidence prior to long duration tests. Consequently, real-time erosion rate measurements offer the potential both to reduce development costs and to enhance knowledge of the dependency of component wear on operating conditions. Several previous studies have used laser induced fluorescence (LIF) to measure real-time, in situ erosion rates of ion thruster accelerator grids. Those studies provided only relative measurements of the erosion rate. In the present investigation, a molybdenum tube was resistively heated such that the evaporation rate yielded densities within the tube on the order of those expected from accelerator grid erosion. A pulsed UV laser was used to pump the ground state molybdenum at 345.64nm, and the non-resonant fluorescence at 550-nm was collected using a bandpass filter and a photomultiplier tube or intensified CCD array. The sensitivity of the fluorescence was evaluated to determine the limitations of the calibration technique. The suitability of the diagnostic calibration technique was assessed for application to ion engine erosion rate measurements.

  4. Strategies for optimizing algal biology for enhanced biomass production

    DOE PAGES

    Barry, Amanda N.; Starkenburg, Shawn R.; Sayre, Richard T.

    2015-02-02

    One of the most environmentally sustainable ways to produce high-energy density (oils) feed stocks for the production of liquid transportation fuels is from biomass. Photosynthetic carbon capture combined with biomass combustion (point source) and subsequent carbon capture and sequestration has also been proposed in the intergovernmental panel on climate change report as one of the most effective and economical strategies to remediate atmospheric greenhouse gases. To maximize photosynthetic carbon capture efficiency and energy-return-on-investment, we must develop biomass production systems that achieve the greatest yields with the lowest inputs. Numerous studies have demonstrated that microalgae have among the greatest potentials formore » biomass production. This is in part due to the fact that all alga cells are photoautotrophic, they have active carbon concentrating mechanisms to increase photosynthetic productivity, and all the biomass is harvestable unlike plants. All photosynthetic organisms, however, convert only a fraction of the solar energy they capture into chemical energy (reduced carbon or biomass). To increase aerial carbon capture rates and biomass productivity, it will be necessary to identify the most robust algal strains and increase their biomass production efficiency often by genetic manipulation. We review recent large-scale efforts to identify the best biomass producing strains and metabolic engineering strategies to improve aerial productivity. In addition, these strategies include optimization of photosynthetic light-harvesting antenna size to increase energy capture and conversion efficiency and the potential development of advanced molecular breeding techniques. To date, these strategies have resulted in up to twofold increases in biomass productivity.« less

  5. Bulk cell density and Wnt/TGFbeta signalling regulate mesendodermal patterning of human pluripotent stem cells

    PubMed Central

    Kempf, Henning; Olmer, Ruth; Haase, Alexandra; Franke, Annika; Bolesani, Emiliano; Schwanke, Kristin; Robles-Diaz, Diana; Coffee, Michelle; Göhring, Gudrun; Dräger, Gerald; Pötz, Oliver; Joos, Thomas; Martinez-Hackert, Erik; Haverich, Axel; Buettner, Falk F. R.; Martin, Ulrich; Zweigerdt, Robert

    2016-01-01

    In vitro differentiation of human pluripotent stem cells (hPSCs) recapitulates early aspects of human embryogenesis, but the underlying processes are poorly understood and controlled. Here we show that modulating the bulk cell density (BCD: cell number per culture volume) deterministically alters anteroposterior patterning of primitive streak (PS)-like priming. The BCD in conjunction with the chemical WNT pathway activator CHIR99021 results in distinct paracrine microenvironments codifying hPSCs towards definitive endoderm, precardiac or presomitic mesoderm within the first 24 h of differentiation, respectively. Global gene expression and secretome analysis reveals that TGFß superfamily members, antagonist of Nodal signalling LEFTY1 and CER1, are paracrine determinants restricting PS progression. These data result in a tangible model disclosing how hPSC-released factors deflect CHIR99021-induced lineage commitment over time. By demonstrating a decisive, functional role of the BCD, we show its utility as a method to control lineage-specific differentiation. Furthermore, these findings have profound consequences for inter-experimental comparability, reproducibility, bioprocess optimization and scale-up. PMID:27934856

  6. Utilization of pyrolytic substrate by microalga Chlamydomonas reinhardtii: cell membrane property change as a response of the substrate toxicity.

    PubMed

    Zhao, Xuefei; Jarboe, Laura; Wen, Zhiyou

    2016-05-01

    Acetic acid derived from fast pyrolysis of lignocellulosic biomass is a promising substrate for microalgae fermentation for producing lipid-rich biomass. However, crude pyrolytic acetic acid solution contains various toxic compounds inhibiting algal growth. It was hypothesized that such an inhibition was mainly due to the cell membrane damage. In this work, the cell membrane property of algal cells was evaluated at various conditions to elucidate the mechanisms of inhibition caused by the pyrolytic substrate solution. It was found that acetic acid itself served a carbon source for boosting algal cell growth but also caused cell membrane leakage. The acetic acid concentration for highest cell density was 4 g/L. Over-liming treatment of crude pyrolytic acetic acid increased the algal growth with a concurrent reduction of cell membrane leakage. Directed evolution of algal strain enhanced cell membrane integrity and thus increased its tolerance to the toxicity of the crude substrate. Statistical analysis shows that there was a significant correlation between the cell growth performance and the cell membrane integrity (leakage) but not membrane fluidity. The addition of cyto-protectants such as Pluronic F68 and Pluronic F127 enhanced the cell membrane integrity and thus, resulted in enhanced cell growth. The transmission electron microscopy (TEM) of algal cells visually confirmed the cell membrane damage as the mechanism of the pyrolytic substrate inhibition. Collectively, this work indicates that the cell membrane is one major reason for the toxicity of pyrolytic acetic acid when being used for algal culture. To better use this pyrolytic substrate, cell membrane of the microorganism needs to be strengthened through either strain improvement or addition of membrane protectant reagents.

  7. Formation of disinfection byproducts from chlor(am)ination of algal organic matter.

    PubMed

    Yang, Xin; Guo, Wanhong; Shen, Qianqian

    2011-12-15

    Algal cells and extracellular organic matter (EOM) of two algae species, Microcystis aeruginosa (blue-green algae) and Chlorella vulgaris (green algae), were characterized. The low specific UV absorbance (SUVA) values of EOM and cells from both algae species indicated the very hydrophilic nature of algal materials. Fluorescence excitation-emission matrix showed that algal EOM and cells were enriched with protein-like and soluble microbial by-product-like matters. The formation potential of a variety of disinfection by-products (DBPs) during chlorination and chloramination of algal cells and EOM were evaluated. Algal cells and EOM of Microcystis and Chlorella exhibited a high potential for DBP formation. Yields of total DBPs varied with the algae cultivation age. Cellular materials contributed more to DBP formation than EOM. The presence of bromide led to higher concentrations of total trihalomethanes (THMs), haloacetonitriles (HANs), and halonitromethanes (HNMs). Bromide also shifted the DBPs to brominated ones. Bromine incorporation was higher in HNMs than in THMs and HANs. Compared to natural organic matter, algae under bloom seasons can contribute significantly to the DBP precursor pool.

  8. Measuring the mass, density, and size of particles and cells using a suspended microchannel resonator

    NASA Astrophysics Data System (ADS)

    Godin, Michel; Bryan, Andrea K.; Burg, Thomas P.; Babcock, Ken; Manalis, Scott R.

    2007-09-01

    We demonstrate the measurement of mass, density, and size of cells and nanoparticles using suspended microchannel resonators. The masses of individual particles are quantified as transient frequency shifts, while the particles transit a microfluidic channel embedded in the resonating cantilever. Mass histograms resulting from these data reveal the distribution of a population of heterogeneously sized particles. Particle density is inferred from measurements made in different carrier fluids since the frequency shift for a particle is proportional to the mass difference relative to the displaced solution. We have characterized the density of polystyrene particles, Escherichia coli, and human red blood cells with a resolution down to 10-4g/cm3.

  9. Laser-induced wakefield acceleration by using density-tapered gas-cell

    NASA Astrophysics Data System (ADS)

    Kim, Minseok; Nam, Inhyuk; Lee, Seungwoo; Suk, Hyyong

    2015-11-01

    The plasma sources with upward density gradient can be used to increase a dephasing length and an accelerating field in laser wakefield acceleration (LWFA) mechanism. As a result, the electron energy accelerated is expected to be increased and we developed a density-tapered gas-cell on this account. Using a 20 TW Ti:Sapphire laser constructed at GIST, we performed the acceleration experiments with the gas-cell and gas-jet with density-gradient. In this presentation, the results of acceleration experiments will be presented in detail.

  10. Optimization towards high density quantum dots for intermediate band solar cells grown by molecular beam epitaxy

    SciTech Connect

    Zhou, D.; Sharma, G.; Fimland, B. O.; Thomassen, S. F.; Reenaas, T. W.

    2010-02-08

    We report high density quantum dots (QDs) formation with optimized growth temperature and V/III ratio. At lower growth temperature, QD density is increased, due to smaller surface migration length of In adatoms. With higher V/III, the QD density is higher but it results in large clusters formation and decreases the QD uniformity. The QD solar cell was fabricated and examined. An extended spectral response in contrast to the GaAs reference cell was presented but the external quantum efficiency at energies higher than GaAs band gap is reduced, resulting from the degradation for the emitter above the strained QD layers.

  11. High Frequency Monitoring for Harmful Algal Blooms

    EPA Science Inventory

    Harmful algal blooms (HABs) are increasingly becoming a significant ecologic, economic, and social driver in the use of water resources. Cyanobacteria and their toxins play an important role in management decisions for drinking water utilities and public health officials. Online ...

  12. Factsheet: Climate Change and Harmful Algal Blooms

    EPA Pesticide Factsheets

    Climate change is predicted to change many environmental conditions that could affect the properties of fresh and marine waters. These changes could favor the growth of harmful algal blooms and habitat changes.

  13. Eukaryotic algal phytochromes span the visible spectrum

    PubMed Central

    Rockwell, Nathan C.; Duanmu, Deqiang; Martin, Shelley S.; Bachy, Charles; Price, Dana C.; Bhattacharya, Debashish; Worden, Alexandra Z.; Lagarias, J. Clark

    2014-01-01

    Plant phytochromes are photoswitchable red/far-red photoreceptors that allow competition with neighboring plants for photosynthetically active red light. In aquatic environments, red and far-red light are rapidly attenuated with depth; therefore, photosynthetic species must use shorter wavelengths of light. Nevertheless, phytochrome-related proteins are found in recently sequenced genomes of many eukaryotic algae from aquatic environments. We examined the photosensory properties of seven phytochromes from diverse algae: four prasinophyte (green algal) species, the heterokont (brown algal) Ectocarpus siliculosus, and two glaucophyte species. We demonstrate that algal phytochromes are not limited to red and far-red responses. Instead, different algal phytochromes can sense orange, green, and even blue light. Characterization of these previously undescribed photosensors using CD spectroscopy supports a structurally heterogeneous chromophore in the far-red–absorbing photostate. Our study thus demonstrates that extensive spectral tuning of phytochromes has evolved in phylogenetically distinct lineages of aquatic photosynthetic eukaryotes. PMID:24567382

  14. Environmental performance of algal biofuel technology options.

    PubMed

    Vasudevan, Venkatesh; Stratton, Russell W; Pearlson, Matthew N; Jersey, Gilbert R; Beyene, Abraham G; Weissman, Joseph C; Rubino, Michele; Hileman, James I

    2012-02-21

    Considerable research and development is underway to produce fuels from microalgae, one of several options being explored for increasing transportation fuel supplies and mitigating greenhouse gas emissions (GHG). This work models life-cycle GHG and on-site freshwater consumption for algal biofuels over a wide technology space, spanning both near- and long-term options. The environmental performance of algal biofuel production can vary considerably and is influenced by engineering, biological, siting, and land-use considerations. We have examined these considerations for open pond systems, to identify variables that have a strong influence on GHG and freshwater consumption. We conclude that algal biofuels can yield GHG reductions relative to fossil and other biobased fuels with the use of appropriate technology options. Further, freshwater consumption for algal biofuels produced using saline pond systems can be comparable to that of petroleum-derived fuels.

  15. Climate Adaptation and Harmful Algal Blooms

    EPA Pesticide Factsheets

    EPA supports local, state and tribal efforts to maintain water quality. A key element of its efforts is to reduce excess nutrient pollution and the resulting adverse impacts, including harmful algal blooms.

  16. Fluid flow through a high cell density fluidized-bed during centrifugal bioreactor culture.

    PubMed

    Detzel, Christopher J; Van Wie, Bernard J; Ivory, Cornelius F

    2010-01-01

    An increasing demand for products such as tissues, proteins, and antibodies from mammalian cell suspension cultures is driving interest in increasing production through high-cell density bioreactors. The centrifugal bioreactor (CCBR) retains cells by balancing settling forces with surface drag forces due to medium throughput and is capable of maintaining cell densities above 10(8) cells/mL. This article builds on a previous study where the fluid mechanics of an empty CCBR were investigated showing fluid flow is nonuniform and dominated by Coriolis forces, raising concerns about nutrient and cell distribution. In this article, we demonstrate that the previously reported Coriolis forces are still present in the CCBR, but masked by the presence of cells. Experimental dye injection observations during culture of 15 microm hybridoma cells show a continual uniform darkening of the cell bed, indicating the region of the reactor containing cells is well mixed. Simulation results also indicate the cell bed is well mixed during culture of mammalian cells ranging in size from 10 to 20 microm. However, simulations also allow for a slight concentration gradient to be identified and attributed to Coriolis forces. Experimental results show cell density increases from 0.16 to 0.26 when centrifugal force is doubled by increasing RPM from 650 to 920 at a constant inlet velocity of 6.5 cm/s; an effect also observed in the simulation. Results presented in this article indicate cells maintained in the CCBR behave as a high-density fluidized bed of cells providing a homogeneous environment to ensure optimal growth conditions.

  17. Fluid Flow through a High Cell Density Fluidized-Bed during Centrifugal Bioreactor Culture

    PubMed Central

    Detzel, Christopher J.; Van Wie, Bernard J.; Ivory, Cornelius F.

    2010-01-01

    An increasing demand for products such as tissues, proteins, and antibodies from mammalian cell suspension cultures is driving interest in increasing production through high-cell density bioreactors. The centrifugal bioreactor (CCBR) retains cells by balancing settling forces with surface drag forces due to medium throughput and is capable of maintaining cell densities above 108 cells/mL. This article builds on a previous study where the fluid mechanics of an empty CCBR were investigated showing fluid flow is nonuniform and dominated by Coriolis forces, raising concerns about nutrient and cell distribution. In this article, we demonstrate that the previously reported Coriolis forces are still present in the CCBR, but masked by the presence of cells. Experimental dye injection observations during culture of 15 μm hybridoma cells show a continual uniform darkening of the cell bed, indicating the region of the reactor containing cells is well mixed. Simulation results also indicate the cell bed is well mixed during culture of mammalian cells ranging in size from 10 to 20 μm. However, simulations also allow for a slight concentration gradient to be identified and attributed to Coriolis forces. Experimental results show cell density increases from 0.16 to 0.26 when centrifugal force is doubled by increasing RPM from 650 to 920 at a constant inlet velocity of 6.5 cm/s; an effect also observed in the simulation. Results presented in this article indicate cells maintained in the CCBR behave as a high-density fluidized bed of cells providing a homogeneous environment to ensure optimal growth conditions. PMID:20205172

  18. Direct conversion of algal biomass to biofuel

    DOEpatents

    Deng, Shuguang; Patil, Prafulla D; Gude, Veera Gnaneswar

    2014-10-14

    A method and system for providing direct conversion of algal biomass. Optionally, the method and system can be used to directly convert dry algal biomass to biodiesels under microwave irradiation by combining the reaction and combining steps. Alternatively, wet algae can be directly processed and converted to fatty acid methyl esters, which have the major components of biodiesels, by reacting with methanol at predetermined pressure and temperature ranges.

  19. Antimony mediated growth of high-density InAs quantum dots for photovoltaic cells

    SciTech Connect

    Tutu, F. K.; Wu, J.; Lam, P.; Tang, M.; Liu, H.; Miyashita, N.; Okada, Y.; Wilson, J.; Allison, R.

    2013-07-22

    We report enhanced solar cell performance using high-density InAs quantum dots. The high-density quantum dot was grown by antimony mediated molecular beam epitaxy. In-plane quantum dot density over 1 × 10{sup 11} cm{sup −2} was achieved by applying a few monolayers of antimony on the GaAs surface prior to quantum dot growth. The formation of defective large clusters was reduced by optimization of the growth temperature and InAs coverage. Comparing with a standard quantum dot solar cell without the incorporation of antimony, the high-density quantum dot solar cell demonstrates a distinct improvement in short-circuit current from 7.4 mA/cm{sup 2} to 8.3 mA/cm{sup 2}.

  20. Comparing new and conventional methods to estimate benthic algal biomass and composition in freshwaters.

    PubMed

    Kahlert, Maria; McKie, Brendan G

    2014-11-01

    We compared conventional microscope-based methods for quantifying biomass and community composition of stream benthic algae with output obtained for these parameters from a new instrument (the BenthoTorch), which measures fluorescence of algal pigments in situ. Benthic algae were studied in 24 subarctic oligotrophic (1.7-26.9, median 7.2 μg total phosphorus L(-1)) streams in Northern Sweden. Readings for biomass of the total algal mat, quantified as chlorophyll a, did not differ significantly between the BenthoTorch (median 0.52 μg chlorophyll a cm(-2)) and the conventional method (median 0.53 μg chlorophyll a cm(-2)). However, quantification of community composition of the benthic algal mat obtained using the BenthoTorch did not match those obtained from conventional methods. The BenthoTorch indicated a dominance of diatoms, whereas microscope observations showed a fairly even distribution between diatoms, blue-green algae (mostly nitrogen-fixing) and green algae (mostly large filamentous), and also detected substantial biovolumes of red algae in some streams. These results most likely reflect differences in the exact parameters quantified by the two methods, as the BenthoTorch does not account for variability in cell size and the presence of non-chlorophyll bearing biomass in estimating the proportion of different algal groups, and does not distinguish red algal chlorophyll from that of other algal groups. Our findings suggest that the BenthoTorch has utility in quantifying biomass expressed as μg chlorophyll a cm(-2), but its output for the relative contribution of different algal groups to benthic algal biomass should be used with caution.

  1. Direct utilization of waste water algal biomass for ethanol production by cellulolytic Clostridium phytofermentans DSM1183.

    PubMed

    Fathima, Anwar Aliya; Sanitha, Mary; Kumar, Thangarathinam; Iyappan, Sellamuthu; Ramya, Mohandass

    2016-02-01

    Direct bioconversion of waste water algal biomass into ethanol using Clostridium phytofermentans DSM1183 was demonstrated in this study. Fermentation of 2% (w/v) autoclaved algal biomass produced ethanol concentration of 0.52 g L(-1) (solvent yield of 0.19 g/g) where as fermentation of acid pretreated algal biomass (2%, w/v) produced ethanol concentration of 4.6 g L(-1) in GS2 media (solvent yield of 0.26 g/g). The control experiment with 2% (w/v) glucose in GS2 media produced ethanol concentration of 2.8 g L(-1) (solvent yield of 0.25 g/g). The microalgal strains from waste water algal biomass were identified as Chlamydomonas dorsoventralis, Graesiella emersonii, Coelastrum proboscideum, Scenedesmus obliquus, Micractinium sp., Desmodesmus sp., and Chlorella sp., based on ITS-2 molecular marker. The presence of glucose, galactose, xylose and rhamnose were detected by high performance liquid chromatography in the algal biomass. Scanning Electron Microscopy observations of fermentation samples showed characteristic morphological changes in algal cells and bioaccessibility of C. phytofermentans.

  2. Investigating why recycling gravity harvested algae increases harvestability and productivity in high rate algal ponds.

    PubMed

    Park, J B K; Craggs, R J; Shilton, A N

    2013-09-15

    It has previously been shown that recycling gravity harvested algae promotes Pediastrum boryanum dominance and improves harvestability and biomass production in pilot-scale High Rate Algal Ponds (HRAPs) treating domestic wastewater. In order to confirm the reproducibility of these findings and investigate the mechanisms responsible, this study utilized twelve 20 L outdoor HRAP mesocosms operated with and without algal recycling. It then compared the recycling of separated solid and liquid components of the harvested biomass against un-separated biomass. The work confirmed that algal recycling promoted P. boryanum dominance, improved 1 h-settleability by >20% and increased biomass productivity by >25% compared with controls that had no recycling. With regard to the improved harvestability, of particular interest was that recycling the liquid fraction alone caused a similar improvement in settleability as recycling the solid fraction. This may be due to the presence of extracellular polymeric substances in the liquid fraction. While there are many possible mechanisms that could account for the increased productivity with algal recycling, all but two were systematically eliminated: (i) the mean cell residence time was extended thereby increasing the algal concentration and more fully utilizing the incident sunlight and, (ii) the relative proportions of algal growth stages (which have different specific growth rates) was changed, resulting in a net increase in the overall growth rate of the culture.

  3. [Algal community structure and water quality assessment on drawdown area of Kaixian waters in Three Gorges Reservoir during winter storage period].

    PubMed

    Guo, Jing-Song; Xie, Dan; Li, Zhe; Chen, Yuan; Sun, Zhi-Yu; Chen, Yong-Bo; Long, Man

    2012-04-01

    The old town area of Kaixian county was flooded and showed reservoir characteristics after the water level of Three Gorges Reservoir got 172. 8 m in December 2008. The aquatic ecology and nutritional status of Kaixian drawdown area after water storage are still rarely reported. To understand the current water environment and changes in algal community structure of Kaixian drawdown area after 172.8 m water level, the algal composition, abundance, biomass distribution and changes of its sampling spots including Hanfeng Lake were observed twice during winter storage period in January and December 2009. The trends in phytoplankton community structure were analyzed and the water quality assessment of nutritional status was carried out. The results indicated that 6 phylums, 37 genera, 69 species of phytoplankton in total were identified in the two sampling, and the dominant species were Dinophyta and Cryptophyta. The cell density and biomass in December 2009 were lower than those in January 2009. The evaluation results of algal population structure and pollution indicators showed that the nutrition level of Kaixian drawdown area during the winter storage period was mesotrophic to eutrophic type, while diversity analysis result indicated moderate pollution.

  4. Culture density influence on the photosynthetic efficiency of microalgae growing under different spectral compositions of light.

    PubMed

    Kula, M; Kalaji, H M; Skoczowski, A

    2017-02-01

    A density in algal suspension causes a significant change in the intensity and spectral composition of light reaching individual cells. Measurements of chlorophyll fluorescence allow us to observe any general changes in the bioenergetic status of photosynthesis. The aim of the study was to determine the effect of cultivation density on the PSII photochemical efficiency of three species of algae (Chlorella vulgaris, Botryococcus braunii and Chlorella emersonii), each with a different rate of growth - high, medium and low - respectively. The cell density of algae in suspension differentiated through the cultivation time (2, 4, and 8days) and the spectral composition of light. The results showed that the density of cultivation led to change in the photosynthetic apparatus of algae. The differences described between each day of cultivation (2, 4, and 8) in the kinetics of chlorophyll a fluorescence intensity in cells of the algal strains under study probably resulted from the different phases of growth of these cultures. In addition the results showed the beneficial effect of far red light on the photosynthetic apparatus and the growth of biomass in investigated algal strains.

  5. Algal and fungal diversity in Antarctic lichens.

    PubMed

    Park, Chae Haeng; Kim, Kyung Mo; Elvebakk, Arve; Kim, Ok-Sun; Jeong, Gajin; Hong, Soon Gyu

    2015-01-01

    The composition of lichen ecosystems except mycobiont and photobiont has not been evaluated intensively. In addition, recent studies to identify algal genotypes have raised questions about the specific relationship between mycobiont and photobiont. In the current study, we analyzed algal and fungal community structures in lichen species from King George Island, Antarctica, by pyrosequencing of eukaryotic large subunit (LSU) and algal internal transcribed spacer (ITS) domains of the nuclear rRNA gene. The sequencing results of LSU and ITS regions indicated that each lichen thallus contained diverse algal species. The major algal operational taxonomic unit (OTU) defined at a 99% similarity cutoff of LSU sequences accounted for 78.7-100% of the total algal community in each sample. In several cases, the major OTUs defined by LSU sequences were represented by two closely related OTUs defined by 98% sequence similarity of ITS domain. The results of LSU sequences indicated that lichen-associated fungi belonged to the Arthoniomycetes, Eurotiomycetes, Lecanoromycetes, Leotiomycetes, and Sordariomycetes of the Ascomycota, and Tremellomycetes and Cystobasidiomycetes of the Basidiomycota. The composition of major photobiont species and lichen-associated fungal community were mostly related to the mycobiont species. The contribution of growth forms or substrates on composition of photobiont and lichen-associated fungi was not evident.

  6. Variations of algal communities cause darkening of a Greenland glacier.

    PubMed

    Lutz, Stefanie; Anesio, Alexandre M; Jorge Villar, Susana E; Benning, Liane G

    2014-08-01

    We have assessed the microbial ecology on the surface of Mittivakkat glacier in SE-Greenland during the exceptional high melting season in July 2012 when the so far most extreme melting rate for the Greenland Ice Sheet has been recorded. By employing a complementary and multi-disciplinary field sampling and analytical approach, we quantified the dramatic changes in the different microbial surface habitats (green snow, red snow, biofilms, grey ice, cryoconite holes). The observed clear change in dominant algal community and their rapidly changing cryo-organic adaptation inventory was linked to the high melting rate. The changes in carbon and nutrient fluxes between different microbial pools (from snow to ice, cryoconite holes and glacial forefronts) revealed that snow and ice algae dominate the net primary production at the onset of melting, and that they have the potential to support the cryoconite hole communities as carbon and nutrient sources. A large proportion of algal cells is retained on the glacial surface and temporal and spatial changes in pigmentation contribute to the darkening of the snow and ice surfaces. This implies that the fast, melt-induced algal growth has a high albedo reduction potential, and this may lead to a positive feedback speeding up melting processes.

  7. Harvesting algal biomass for biofuels using ultrafiltration membranes.

    PubMed

    Zhang, Xuezhi; Hu, Qiang; Sommerfeld, Milton; Puruhito, Emil; Chen, Yongsheng

    2010-07-01

    The objective of this paper is to develop efficient technologies for harvesting of algal biomass using membrane filtration. Foulants were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Anti-fouling strategies were established, such as using air-assisted backwash with air scouring, and optimizing operational conditions. A model was also developed to predict the flux decline and final concentration based on a resistance-in-series analysis and a cake development calculation. The results showed that the buildup of the algal cake layer and adsorption of algogenic organic matter (AOM) (mainly protein, polysaccharides or polysaccharide-like substances) on the membrane caused membrane fouling. The cake layer buildup was removed by conducting an air-assisted backwash every 15 min. The adsorbed AOM could be removed by soaking the membrane in 400mg/L NaClO for 1h. In our experiment the algal suspension was concentrated 150 times, to give a final cell concentration of 154.85g/L. The harvesting efficiency and average flux were 46.01 g/(m(2)h) and 45.50 L/(m(2)h), respectively. No algae were found in the permeate, which had an average turbidity of 0.018 Nephelometric Turbidity Units (NTU). The flux decline predicted by the model under different conditions was consistent with the experimental results.

  8. Cell Density-Dependent Increase in Tyrosine-Monophosphorylated ERK2 in MDCK Cells Expressing Active Ras or Raf

    PubMed Central

    Kawabata, Noriyuki; Matsuda, Michiyuki

    2016-01-01

    The extracellular signal-regulated kinase (ERK) is one of the principal hub proteins that transmit growth signals from upstream oncogene products including Ras and BRaf to downstream effector proteins. However, there are both reports supporting and refuting the increase in ERK activity in cancer tissues expressing the active Ras and BRaf proteins. We considered that the cell density might account for this discrepancy. To examine this possibility, we prepared Madin-Darby canine kidney (MDCK) cells that expressed an active HRas, NRas, KRas, or BRaf and an ERK biosensor based on the principle of Förster resonance energy transfer (FRET). As we anticipated, expression of the active Ras or BRaf increased ERK activity at low cell densities. However, the ERK activity was markedly suppressed at high cell densities irrespective of the expression of the active Ras or BRaf. Western blotting analysis with Phos-tag gel revealed the decrease of tyrosine and threonine-diphosphorylated active ERK and the increase of tyrosine-monophosphorylated inactive ERK at high cell density. In addition, we found that calyculin A, an inhibitor for PPP-subfamily protein serine/threonine phosphatases, decreased the tyrosine-monophosphorylated ERK. Our study suggests that PPP-subfamily phosphatases may be responsible for cell density-dependent ERK dephosphorylation in cancer cells expressing active Ras or BRaf protein. PMID:27936234

  9. Substrate microtopography can enhance cell adhesive and migratory responsiveness to matrix ligand density.

    PubMed

    Ranucci, C S; Moghe, P V

    2001-02-01

    The regulation of cell motility by ligand density on substrates with variable microtopography is not well understood. In this report, we studied the adhesion and motility behavior of HepG2 cells on microtextured poly(glycolic-co-lactic)acid (PGLA) copolymer substrates, whose surface bioactivity was differentially modified through the adsorption of 0-5.5 ng/cm(2) collagen. Microtextured PGLA substrates were fabricated as thin films with a uniform surface distribution of micropores of median size of 3.1 +/- 1.5 microm and three-dimensional root mean squared roughness of 0.253 microm. Even in the absence of collagen, cells on microtextured substrates responded to substrate topography by exhibiting a 200% increase in adhesion strength compared with untextured controls and ventral localization of the intracellular adhesion protein vinculin. Further enhancement in adhesion strength (420% over untextured, untreated substrates) was demonstrated with bioactivated, microtextured surfaces, indicating that cell adhesion responses to topography and surface ligand density were cooperative. Our motility studies of cells on untextured substrates adsorbed with different levels of collagen demonstrated that a classical biphasic relationship between the cell population averaged migration rate, mu, and the collagen ligand density was preserved. However, comparison of cell motility responses between untextured and microtextured substrates indicates that the motility versus ligand density curve shifted, such that equivalent levels of cell motility were achieved at lower ligand density on microtextured surfaces. Furthermore, the maximum mu values achieved on the microtextured substrates exceeded those on untextured substrates by twofold. Taken together, we show that the magnitude of subcellular scale microtexture of a polymer substrate can sensitize the cell motility responsiveness to substrate ligand concentration; we suggest that the underlying mechanisms involve alteration in the

  10. EFFECTS OF PLATING DENSITY AND CULTURE TIME ON BONE MARROW STROMAL CELL CHARACTERISTICS

    PubMed Central

    Neuhuber, Birgit; Swanger, Sharon A.; Howard, Linda; Mackay, Alastair; Fischer, Itzhak

    2008-01-01

    Objective Bone marrow stromal cells (MSC) are multipotent adult stem cells that have emerged as promising candidates for cell therapy in disorders including cardiac infarction, stroke and spinal cord injury. While harvesting methods used by different laboratories are relatively standard, MSC culturing protocols vary widely. This study is aimed at evaluating the effects of initial plating density and total time in culture on proliferation, cell morphology, and differentiation potential of heterogeneous MSC cultures and more homogeneous cloned subpopulations. Methods Rat MSC were plated at 20, 200 and 2000 cells/cm2 and grown to 50% confluency. The numbers of population doublings and doubling times were determined within and across multiple passages. Changes in cell morphology and differentiation potential to adipogenic, chondrogenic, and osteogenic lineages were evaluated and compared among early, intermediate and late passages, as well as between heterogeneous and cloned MSC populations. Results We found optimal cell growth at a plating density of 200 cells/cm2. Cultures derived from all plating densities developed increased proportions of flat cells over time. Assays for chondrogenesis, osteogenesis and adipogenesis showed that heterogeneous MSC plated at all densities sustained the potential for all three mesenchymal phenotypes through at least passage 5; the flat subpopulation lost adipogenic and chondrogenic potential. Conclusion Our findings suggest that the initial plating density is not critical for maintaining a well-defined, multipotent MSC population. Time in culture, however, affects cell characteristics, suggesting that cell expansion should be limited, especially until the specific characteristics of different MSC subpopulations are better understood. PMID:18495329

  11. Expansion of adipose mesenchymal stromal cells is affected by human platelet lysate and plating density.

    PubMed

    Cholewa, Dominik; Stiehl, Thomas; Schellenberg, Anne; Bokermann, Gudrun; Joussen, Sylvia; Koch, Carmen; Walenda, Thomas; Pallua, Norbert; Marciniak-Czochra, Anna; Suschek, Christoph V; Wagner, Wolfgang

    2011-01-01

    The composition of mesenchymal stromal cells (MSCs) changes in the course of in vitro culture expansion. Little is known how these cell preparations are influenced by culture media, plating density, or passaging. In this study, we have isolated MSCs from human adipose tissue in culture medium supplemented with either fetal calf serum (FCS) or human platelet lysate (HPL). In addition, culture expansion was simultaneously performed at plating densities of 10 or 10,000 cells/cm(2). The use of FCS resulted in larger cells, whereas HPL significantly enhanced proliferation. Notably, HPL also facilitated expansion for more population doublings than FCS (43 ± 3 vs. 22 ± 4 population doubling; p < 0.001), while plating density did not have a significant effect on long-term growth curves. To gain further insight into population dynamics, we conceived a cellular automaton model to simulate expansion of MSCS. It is based on the assumptions that the number of cell divisions is limited and that due to contact inhibition proliferation occurs only at the rim of colonies. The model predicts that low plating densities result in more heterogeneity with regard to cell division history, and favor subpopulations of higher migratory activity. In summary, HPL is a suitable serum supplement for isolation of MSC from adipose tissue and facilitates more population doublings than FCS. Cellular automaton computer simulations provided additional insights into how complex population dynamics during long-term expansion are affected by plating density and migration.

  12. ALGAL RESPONSE TO NUTRIENT ENRICHMENT IN FORESTED OLIGOTROPHIC STREAM(1).

    PubMed

    Veraart, Annelies J; Romaní, Anna M; Tornés, Elisabet; Sabater, Sergi

    2008-06-01

    Nutrient input in streams alters the density and species composition of attached algal communities in open systems. However, in forested streams, the light reaching the streambed (rather than the local nutrient levels) may limit the growth of these communities. A nutrient-enrichment experiment in a forested oligotrophic stream was performed to test the hypothesis that nutrient addition has only minor effects on the community composition of attached algae and cyanobacteria under light limitation. Moderate nutrient addition consisted of increasing basal phosphorus (P) concentrations 3-fold and basal nitrogen (N) concentrations 2-fold. Two upstream control reaches were compared to a downstream reach before and after nutrient addition. Nutrients were added continuously to the downstream reach for 1 year. Algal biofilms growing on ceramic tiles were sampled and identified for more than a year before nutrient addition to 12 months after. Diatoms were the most abundant taxonomic group in the three stream reaches. Nutrient enrichment caused significant variations in the composition of the diatom community. While some taxa showed significant decreases (e.g., Achnanthes minutissima, Gomphonema angustum), increases for other taxa (such as Rhoicosphenia abbreviata and Amphora ovalis) were detected in the enriched reach (for taxonomic authors, see Table 2). Epiphytic and adnate taxa of large size were enhanced, particularly during periods of favorable growth conditions (spring). Nutrients also caused a change in the algal chl a, which increased from 0.5-5.8 to 2.1-10.7 μg chl · cm(-2) . Our results indicate that in oligotrophic forested streams, long-term nutrient addition has significant effects on the algal biomass and community composition, which are detectable despite the low light availability caused by the tree canopy. Low light availability moderates but does not detain the long-term tendency toward a nutrient-tolerant community. Furthermore, the effects

  13. Tubular photobioreactor design for algal cultures.

    PubMed

    Molina, E; Fernández, J; Acién, F G; Chisti, Y

    2001-12-28

    Principles of fluid mechanics, gas-liquid mass transfer, and irradiance controlled algal growth are integrated into a method for designing tubular photobioreactors in which the culture is circulated by an airlift pump. A 0.2 m(3) photobioreactor designed using the proposed approach was proved in continuous outdoor culture of the microalga Phaeodactylum tricornutum. The culture performance was assessed under various conditions of irradiance, dilution rates and liquid velocities through the tubular solar collector. A biomass productivity of 1.90 g l(-1) d(-1) (or 32 g m(-2) d(-1)) could be obtained at a dilution rate of 0.04 h(-1). Photoinhibition was observed during hours of peak irradiance; the photosynthetic activity of the cells recovered a few hours later. Linear liquid velocities of 0.50 and 0.35 m s(-1) in the solar collector gave similar biomass productivities, but the culture collapsed at lower velocities. The effect of dissolved oxygen concentration on productivity was quantified in indoor conditions; dissolved oxygen levels higher or lower than air saturation values reduced productivity. Under outdoor conditions, for given levels of oxygen supersaturation, the productivity decline was greater outdoors than indoors, suggesting that under intense outdoor illumination photooxidation contributed to loss of productivity in comparison with productivity loss due to oxygen inhibition alone. Dissolved oxygen values at the outlet of solar collector tube were up to 400% of air saturation.

  14. GaAsP solar cells on GaP/Si with low threading dislocation density

    NASA Astrophysics Data System (ADS)

    Yaung, Kevin Nay; Vaisman, Michelle; Lang, Jordan; Lee, Minjoo Larry

    2016-07-01

    GaAsP on Si tandem cells represent a promising path towards achieving high efficiency while leveraging the Si solar knowledge base and low-cost infrastructure. However, dislocation densities exceeding 108 cm-2 in GaAsP cells on Si have historically hampered the efficiency of such approaches. Here, we report the achievement of low threading dislocation density values of 4.0-4.6 × 106 cm-2 in GaAsP solar cells on GaP/Si, comparable with more established metamorphic solar cells on GaAs. Our GaAsP solar cells on GaP/Si exhibit high open-circuit voltage and quantum efficiency, allowing them to significantly surpass the power conversion efficiency of previous devices. The results in this work show a realistic path towards dual-junction GaAsP on Si cells with efficiencies exceeding 30%.

  15. Microalgal cell disruption via ultrasonic nozzle spraying.

    PubMed

    Wang, M; Yuan, W

    2015-01-01

    The objective of this study was to understand the effect of operating parameters, including ultrasound amplitude, spraying pressure, nozzle orifice diameter, and initial cell concentration on microalgal cell disruption and lipid extraction in an ultrasonic nozzle spraying system (UNSS). Two algal species including Scenedesmus dimorphus and Nannochloropsis oculata were evaluated. Experimental results demonstrated that the UNSS was effective in the disruption of microalgal cells indicated by significant changes in cell concentration and Nile red-stained lipid fluorescence density between all treatments and the control. It was found that increasing ultrasound amplitude generally enhanced cell disruption and lipid recovery although excessive input energy was not necessary for best results. The effect of spraying pressure and nozzle orifice diameter on cell disruption and lipid recovery was believed to be dependent on the competition between ultrasound-induced cavitation and spraying-generated shear forces. Optimal cell disruption was not always achieved at the highest spraying pressure or biggest nozzle orifice diameter; instead, they appeared at moderate levels depending on the algal strain and specific settings. Increasing initial algal cell concentration significantly reduced cell disruption efficiency. In all UNSS treatments, the effectiveness of cell disruption and lipid recovery was found to be dependent on the algal species treated.

  16. Evaluating algal growth performance and water use efficiency of pilot-scale revolving algal biofilm (RAB) culture systems.

    PubMed

    Gross, Martin; Mascarenhas, Vernon; Wen, Zhiyou

    2015-10-01

    A Revolving Algal Biofilm (RAB) growth system in which algal cells are attached to a flexible material rotating between liquid and gas phases has been developed. In this work, different configurations of RAB systems were developed at pilot-scale by retrofitting the attachment materials to a raceway pond (2000-L with 8.5 m(2) footprint area) and a trough reservoir (150 L with 3.5 m(2) footprint area). The algal growth performance and chemical composition, as well as the water evaporative loss and specific water consumption were evaluated over a period of nine months in a greenhouse environment near Boone, Iowa USA. Additionally a raceway pond was run in parallel, which served as a control. On average the raceway-based RAB and the trough-based RAB outperformed the control pond by 309% and 697%, respectively. A maximum productivity of 46.8 g m(-2) day(-1) was achieved on the trough-based RAB system. The evaporative water loss of the RAB system was modeled based on an energy balance analysis and was experimentally validated. While the RAB system, particularly the trough-based RAB, had higher water evaporative loss, the specific water consumption per unit of biomass produced was only 26% (raceway-based RAB) and 7% (trough-based RAB) of that of the control pond. Collectively, this research shows that the RAB system is an efficient algal culture system and has great potential to commercially produce microalgae with high productivity and efficient water use.

  17. Tip-growing cells of the moss Ceratodon purpureus Are gravitropic in high-density media

    NASA Technical Reports Server (NTRS)

    Schwuchow, Jochen Michael; Kern, Volker Dieter; Sack, Fred David

    2002-01-01

    Gravity sensing in plants and algae is hypothesized to rely upon either the mass of the entire cell or that of sedimenting organelles (statoliths). Protonemata of the moss Ceratodon purpureus show upward gravitropism and contain amyloplasts that sediment. If moss sensing were whole-cell based, then media denser than the cell should prevent gravitropism or reverse its direction. Cells that were inverted or reoriented to the horizontal displayed distinct negative gravitropism in solutions of iodixanol with densities of 1.052 to 1.320 as well as in bovine serum albumin solutions with densities of 1.037 to 1.184 g cm(-3). Studies using tagged molecules of different sizes and calculations of diffusion times suggest that both types of media penetrate through the apical cell wall. Estimates of the density of the apical cell range from 1.004 to 1.085. Because protonemata grow upward when the cells have a density that is lower than the surrounding medium, gravitropic sensing probably utilizes an intracellular mass in moss protonemata. These data provide additional support for the idea that sedimenting amyloplasts function as statoliths in gravitropism.

  18. From immobilized cells to motile cells on a bed-of-nails: effects of vertical nanowire array density on cell behaviour

    PubMed Central

    Persson, Henrik; Li, Zhen; Tegenfeldt, Jonas O.; Oredsson, Stina; Prinz, Christelle N.

    2015-01-01

    The field of vertical nanowire array-based applications in cell biology is growing rapidly and an increasing number of applications are being explored. These applications almost invariably rely on the physical properties of the nanowire arrays, creating a need for a better understanding of how their physical properties affect cell behaviour. Here, we investigate the effects of nanowire density on cell migration, division and morphology for murine fibroblasts. Our results show that few nanowires are sufficient to immobilize cells, while a high nanowire spatial density enables a ”bed-of-nails” regime, where cells reside on top of the nanowires and are fully motile. The presence of nanowires decreases the cell proliferation rate, even in the “bed-of-nails” regime. We show that the cell morphology strongly depends on the nanowire density. Cells cultured on low (0.1 μm−2) and medium (1 μm−2) density substrates exhibit an increased number of multi-nucleated cells and micronuclei. These were not observed in cells cultured on high nanowire density substrates (4 μm−2). The results offer important guidelines to minimize cell-function perturbations on nanowire arrays. Moreover, these findings offer the possibility to tune cell proliferation and migration independently by adjusting the nanowire density, which may have applications in drug testing. PMID:26691936

  19. From immobilized cells to motile cells on a bed-of-nails: effects of vertical nanowire array density on cell behaviour.

    PubMed

    Persson, Henrik; Li, Zhen; Tegenfeldt, Jonas O; Oredsson, Stina; Prinz, Christelle N

    2015-12-22

    The field of vertical nanowire array-based applications in cell biology is growing rapidly and an increasing number of applications are being explored. These applications almost invariably rely on the physical properties of the nanowire arrays, creating a need for a better understanding of how their physical properties affect cell behaviour. Here, we investigate the effects of nanowire density on cell migration, division and morphology for murine fibroblasts. Our results show that few nanowires are sufficient to immobilize cells, while a high nanowire spatial density enables a "bed-of-nails" regime, where cells reside on top of the nanowires and are fully motile. The presence of nanowires decreases the cell proliferation rate, even in the "bed-of-nails" regime. We show that the cell morphology strongly depends on the nanowire density. Cells cultured on low (0.1 μm(-2)) and medium (1 μm(-2)) density substrates exhibit an increased number of multi-nucleated cells and micronuclei. These were not observed in cells cultured on high nanowire density substrates (4 μm(-2)). The results offer important guidelines to minimize cell-function perturbations on nanowire arrays. Moreover, these findings offer the possibility to tune cell proliferation and migration independently by adjusting the nanowire density, which may have applications in drug testing.

  20. From immobilized cells to motile cells on a bed-of-nails: effects of vertical nanowire array density on cell behaviour

    NASA Astrophysics Data System (ADS)

    Persson, Henrik; Li, Zhen; Tegenfeldt, Jonas O.; Oredsson, Stina; Prinz, Christelle N.

    2015-12-01

    The field of vertical nanowire array-based applications in cell biology is growing rapidly and an increasing number of applications are being explored. These applications almost invariably rely on the physical properties of the nanowire arrays, creating a need for a better understanding of how their physical properties affect cell behaviour. Here, we investigate the effects of nanowire density on cell migration, division and morphology for murine fibroblasts. Our results show that few nanowires are sufficient to immobilize cells, while a high nanowire spatial density enables a ”bed-of-nails” regime, where cells reside on top of the nanowires and are fully motile. The presence of nanowires decreases the cell proliferation rate, even in the “bed-of-nails” regime. We show that the cell morphology strongly depends on the nanowire density. Cells cultured on low (0.1 μm-2) and medium (1 μm-2) density substrates exhibit an increased number of multi-nucleated cells and micronuclei. These were not observed in cells cultured on high nanowire density substrates (4 μm-2). The results offer important guidelines to minimize cell-function perturbations on nanowire arrays. Moreover, these findings offer the possibility to tune cell proliferation and migration independently by adjusting the nanowire density, which may have applications in drug testing.

  1. Algal Supply System Design - Harmonized Version

    SciTech Connect

    Abodeely, Jared; Stevens, Daniel; Ray, Allison; Newby, Deborah; Schaller, Kastli

    2013-03-01

    The objective of this design report is to provide an assessment of current technologies used for production, dewatering, and converting microalgae cultivated in open-pond systems to biofuel. The original draft design was created in 2011 and has subsequently been brought into agreement with the DOE harmonized model. The design report extends beyond this harmonized model to discuss some of the challenges with assessing algal production systems, including the ability to (1) quickly assess alternative algal production system designs, (2) assess spatial and temporal variability, and (3) perform large-scale assessments considering multiple scenarios for thousands of potential sites. The Algae Logistics Model (ALM) was developed to address each of these limitations of current modeling efforts to enable assessment of the economic feasibility of algal production systems across the United States. The (ALM) enables (1) dynamic assessments using spatiotemporal conditions, (2) exploration of algal production system design configurations, (3) investigation of algal production system operating assumptions, and (4) trade-off assessments with technology decisions and operating assumptions. The report discusses results from the ALM, which is used to assess the baseline design determined by harmonization efforts between U.S. DOE national laboratories. Productivity and resource assessment data is provided by coupling the ALM with the Biomass Assessment Tool developed at PNNL. This high-fidelity data is dynamically passed to the ALM and used to help better understand the impacts of spatial and temporal constraints on algal production systems by providing a cost for producing extracted algal lipids annually for each potential site.

  2. Langerhans Cells Regulate Cutaneous Innervation Density and Mechanical Sensitivity in Mouse Footpad

    PubMed Central

    Doss, Argenia L. N.; Smith, Peter G.

    2014-01-01

    Langerhans cells are epidermal dendritic cells responsible for antigen presentation during an immune response. Langerhans cells associate intimately with epidermal sensory axons. While there is evidence that Langerhans cells may produce neurotrophic factors, a role in regulating cutaneous innervation has not been established. We used genetically engineered mice in which the diphtheria toxin (DT) receptor is targeted to Langerhans cells (Lang-DTR mice) to assess sensory axon-dendritic cell interactions. Diphtheria toxin administration to wild type mice did not affect epidermal structure, Langerhans cell content, or innervation density. A DT administration regimen supramaximal for completely ablating epidermal Langerhans cells in Lang-DTR mice reduced PGP 9.5–immunoreactive total innervation and calcitonin gene related peptide–immunoreactive peptidergic nociceptor innervation. Quantitative real-time polymerase chain reaction showed that epidermal gene expression of brain derived neurotrophic factor was unchanged, but nerve growth factor and glial cell line-derived neurotrophic factor mRNAs were reduced. Behavioral testing showed that, while thermal sensitivity was unaffected, mice depleted of Langerhans cells displayed mechanical hypersensitivity. These findings provide evidence that Langerhans cells play an important role in determining cutaneous sensory innervation density and mechanical sensitivity. This may involve alterations in neurotrophin production by Langerhans or other epidermal cells, which in turn may affect mechanical sensitivity directly or as a result of neuropathic changes. PMID:24970748

  3. Reporter gene assays for algal-derived toxins.

    PubMed

    Fairey, E R; Ramsdell, J S

    1999-01-01

    We have modified the cell-based directed cytotoxicity assay for sodium channel and calcium channel active phycotoxins using a c-fos-luciferase reporter gene construct. In this report we describe the conceptual basis to the development of reporter gene assays for algal-derived toxins and summarize both published and unpublished data using this method. N2A mouse neuroblastoma cells, which express voltage-dependent sodium channels, were stably transfected with the reporter gene c-fos-luc, which contains the firefly luciferase gene under the transcriptional regulation of the human c-fos response element. The characteristics of the N2A reporter gene assay were determined by dose response with brevetoxin and ciguatoxin. Brevetoxin-1 and ciguatoxin-1 induced c-fos-luc with an EC50 of 4.6 and 3.0 ng ml(-1), respectively. Saxitoxin caused a concentration-dependent inhibition of brevetoxin-1 induction of c-fos-luc with an EC50 of 3.5 ng ml(-1). GH4C1 rat pituitary cells, which lack voltage-dependent sodium channels but express voltage-dependent calcium channels, were also stably transfected with the c-fos-luc. GH4C1 cells expressing c-fos-luciferase were responsive to maitotoxin (1 ng ml(-1)) and a putative toxin produced by Pfiesteria piscicida. Although reporter gene assays are not designed to replace existing detection methods used to measure toxin activity in seafood, they do provide a valuable means to screen algal cultures for toxin activity, to conduct assay-guided fractionation and to characterize pharmacologic properties of algal toxins.

  4. High-density polymer microarrays: identifying synthetic polymers that control human embryonic stem cell growth.

    PubMed

    Hansen, Anne; Mjoseng, Heidi K; Zhang, Rong; Kalloudis, Michail; Koutsos, Vasileios; de Sousa, Paul A; Bradley, Mark

    2014-06-01

    The fabrication of high-density polymer microarray is described, allowing the simultaneous and efficient evaluation of more than 7000 different polymers in a single-cellular-based screen. These high-density polymer arrays are applied in the search for synthetic substrates for hESCs culture. Up-scaling of the identified hit polymers enables long-term cellular cultivation and promoted successful stem-cell maintenance.

  5. Novel cholesterol feeding strategy enables a high-density cultivation of cholesterol-dependent NS0 cells in linear low-density polyethylene-based disposable bioreactors.

    PubMed

    Tao, Yiwen; Yusuf-Makagiansar, Helena; Shih, Jennifer; Ryll, Thomas; Sinacore, Marty

    2012-08-01

    We have developed a perfusion-based high cell density (HD) cell banking and inoculum expansion procedure for a cholesterol-dependent NS0 myeloma cell line using linear low-density polyethylene-based disposable bioreactors. Challenges associated with cholesterol-polymer interactions, which suppress cholesterol-dependent NS0 myeloma cell growth, were overcome using a novel cholesterol feeding protocol that included a combination of two cholesterol formulations: an ethanol-based formulation and an aqueous formulation. Using a cholesterol feed optimized for HD cell culture in a disposable bioreactor perfusion system, cell densities of >25 × 10(6) viable cells/ml at ≥ 90 % cell viability were achieved. Vials of high density cell banks were created by filling 90-100 × 10(6) viable cells/ml in 5 ml cryotube vials. Implementation of the HD cell banks enabled a significant reduction in the number of step operations in the inoculum expansion phase in a large-scale manufacturing setting.

  6. A tunable sequential and periodic pattern formed by coupling cell motility with density

    NASA Astrophysics Data System (ADS)

    Huang, Jiandong

    2011-03-01

    The ability of living organisms to form patterns is an untapped resource for synthetic biology. We aim to generate unique patterns by rewiring the genetic circuitry controlling cell motility. Specifically, E. coli cells are programmed to regulate their movement by sensing local cell density. Interesting patterns are formed by newly engineered cells. An engineered low-density mover strain spreads outwards and autonomously forms a sequential and periodic pattern. Moreover, we build a theoretical model that satisfactorily fits our current experimental data, and also predicts some parameters which may significantly affect the pattern formation. The study of this self-organized spatial distribution of cells may help us to probe the principles underlying the formation of natural biological patterns, and to prepare for future engineering of biological structures.

  7. Very high cell density perfusion of CHO cells anchored in a non-woven matrix-based bioreactor.

    PubMed

    Zhang, Ye; Stobbe, Per; Silvander, Christian Orrego; Chotteau, Véronique

    2015-11-10

    Recombinant Chinese Hamster Ovary (CHO) cells producing IgG monoclonal antibody were cultivated in a novel perfusion culture system CellTank, integrating the bioreactor and the cell retention function. In this system, the cells were harbored in a non-woven polyester matrix perfused by the culture medium and immersed in a reservoir. Although adapted to suspension, the CHO cells stayed entrapped in the matrix. The cell-free medium was efficiently circulated from the reservoir into- and through the matrix by a centrifugal pump placed at the bottom of the bioreactor resulting in highly homogenous concentrations of the nutrients and metabolites in the whole system as confirmed by measurements from different sampling locations. A real-time biomass sensor using the dielectric properties of living cells was used to measure the cell density. The performances of the CellTank were studied in three perfusion runs. A very high cell density measured as 200 pF/cm (where 1 pF/cm is equivalent to 1 × 10(6)viable cells/mL) was achieved at a perfusion rate of 10 reactor volumes per day (RV/day) in the first run. In the second run, the effect of cell growth arrest by hypothermia at temperatures lowered gradually from 37 °C to 29 °C was studied during 13 days at cell densities above 100 pF/cm. Finally a production run was performed at high cell densities, where a temperature shift to 31 °C was applied at cell density 100 pF/cm during a production period of 14 days in minimized feeding conditions. The IgG concentrations were comparable in the matrix and in the harvest line in all the runs, indicating no retention of the product of interest. The cell specific productivity was comparable or higher than in Erlenmeyer flask batch culture. During the production run, the final harvested IgG production was 35 times higher in the CellTank compared to a repeated batch culture in the same vessel volume during the same time period.

  8. Two coexisting tank bromeliads host distinct algal communities on a tropical inselberg.

    PubMed

    Carrias, J-F; Céréghino, R; Brouard, O; Pélozuelo, L; Dejean, A; Couté, A; Corbara, B; Leroy, C

    2014-09-01

    The tank bromeliads Aechmea aquilega (Salisb.) and Catopsis berteroniana (Schultes f.) coexist on a sun-exposed Neotropical inselberg in French Guiana, where they permit conspicuous freshwater pools to form that differ in size, complexity and detritus content. We sampled the algal communities (both eukaryotic and cyanobacterial taxa, including colourless forms) inhabiting either A. aquilega (n = 31) or C. berteroniana (n = 30) and examined differences in community composition and biomass patterns in relation to several biotic and abiotic variables. Chlorella sp. and Bumilleriopsis sp. were the most common taxa and dominated the algal biomass in A. aquilega and C. berteroniana, respectively. Using a redundancy analysis, we found that water volume, habitat complexity and the density of phagotrophic protozoa and collector-gatherer invertebrates were the main factors explaining the distribution of the algal taxa among the samples. Hierarchical clustering procedures based on abundance and presence/absence data clearly segregated the samples according to bromeliad species, revealing that the algal communities in the smaller bromeliad species were not a subset of the communities found in the larger bromeliad species. We conclude that, even though two coexisting tank bromeliad populations create adjacent aquatic habitats, each population hosts a distinct algal community. Hence, bromeliad diversity is thought to promote the local diversity of freshwater algae in the Neotropics.

  9. Stress signaling from human mammary epithelial cells contributes to phenotypes of mammographic density.

    PubMed

    DeFilippis, Rosa Anna; Fordyce, Colleen; Patten, Kelley; Chang, Hang; Zhao, Jianxin; Fontenay, Gerald V; Kerlikowske, Karla; Parvin, Bahram; Tlsty, Thea D

    2014-09-15

    Telomere malfunction and other types of DNA damage induce an activin A-dependent stress response in mortal nontumorigenic human mammary epithelial cells that subsequently induces desmoplastic-like phenotypes in neighboring fibroblasts. Some characteristics of this fibroblast/stromal response, such as reduced adipocytes and increased extracellular matrix content, are observed not only in tumor tissues but also in disease-free breast tissues at high risk for developing cancer, especially high mammographic density tissues. We found that these phenotypes are induced by repression of the fatty acid translocase CD36, which is seen in desmoplastic and disease-free high mammographic density tissues. In this study, we show that epithelial cells from high mammographic density tissues have more DNA damage signaling, shorter telomeres, increased activin A secretion and an altered DNA damage response compared with epithelial cells from low mammographic density tissues. Strikingly, both telomere malfunction and activin A expression in epithelial cells can repress CD36 expression in adjacent fibroblasts. These results provide new insights into how high mammographic density arises and why it is associated with breast cancer risk, with implications for the definition of novel invention targets (e.g., activin A and CD36) to prevent breast cancer.

  10. Stress Signaling from Human Mammary Epithelial Cells Contributes to Phenotypes of Mammographic Density

    PubMed Central

    Patten, Kelley; Chang, Hang; Zhao, Jianxin; Fontenay, Gerald V.; Kerlikowske, Karla; Parvin, Bahram; Tlsty, Thea D.

    2014-01-01

    Telomere malfunction and other types of DNA damage induce an activin A-dependent stress response in mortal non-tumorigenic human mammary epithelial cells that subsequently induces desmoplastic-like phenotypes in neighboring fibroblasts. Some characteristics of this fibroblast/stromal response, such as reduced adipocytes and increased extracellular matrix content, are observed not only in tumor tissues but also in disease-free breast tissues at high risk for developing cancer, especially high mammographic density tissues. We found that these phenotypes are induced by repression of the fatty acid translocase CD36, which is seen in desmoplastic and disease-free high mammographic density tissues. In this study, we show that epithelial cells from high mammographic density tissues have more DNA damage signaling, shorter telomeres, increased activin A secretion and an altered DNA damage response compared to epithelial cells from low mammographic density tissues. Strikingly, both telomere malfunction and activin A expression in epithelial cells can repress CD36 expression in adjacent fibroblasts. These results provide new insights into how high mammographic density arises and why it is associated with breast cancer risk, with implications for the definition of novel invention targets (e.g. activin A, CD36) to prevent breast cancer. PMID:25172842

  11. Platy algal banks: Modern and ancient

    SciTech Connect

    Brinton, L. )

    1990-05-01

    Plaly algal banks and associated cycles in the lower Ismay zone of the Paradox Formation are exposed along the walls of the San Juan River canyon, southeastern Utah. These complexes closely resemble algal bank reservoirs in the lower Ismay zone of Ismay and Cache, and possibly other Paradox basin fields. Similarities include facies relationships, lateral and vertical textural variations, and early diagenesis. Extensive algal banks exposed along the San Juan canyon generally have flat bases and mound and swale topographic surfaces, and are separated by interbank channels. The surficial mounds have a regular amplitude and wavelength suggesting a hydrologic rather than biologic influence on topography. The banks themselves, however, are believed to be thick, predominantly in-situ accumulations of platy algae. Distribution of algal banks can be mapped on a field scale; mound and swale topographic features may be identified in core on the basis of depositional and early diagenetic characteristics. Halimeda bioherms (Holocene) cover large areas behind the Great Barrier Reef, developing adjacent to the deep passes that separate the individual reefs. These large in-situ accumulations (20-50 m deep) display similar bank geometries, interbank features, topographic features, vertical textural sequence (including porosity type and distribution), and facies relationships to algal banks observed in the outcropping and subsurface Paradox Formation. Although the hydrodynamic and paleobathymetric settings differ markedly between these two examples, analogies between the mounds themselves are very close. The resemblance lends relevance to exploration and development drilling.

  12. Microbial communities mediating algal detritus turnover under anaerobic conditions

    PubMed Central

    Morrison, Jessica M.; Murphy, Chelsea L.; Baker, Kristina; Zamor, Richard M.; Nikolai, Steve J.; Wilder, Shawn; Elshahed, Mostafa S.

    2017-01-01

    Background Algae encompass a wide array of photosynthetic organisms that are ubiquitously distributed in aquatic and terrestrial habitats. Algal species often bloom in aquatic ecosystems, providing a significant autochthonous carbon input to the deeper anoxic layers in stratified water bodies. In addition, various algal species have been touted as promising candidates for anaerobic biogas production from biomass. Surprisingly, in spite of its ecological and economic relevance, the microbial community involved in algal detritus turnover under anaerobic conditions remains largely unexplored. Results Here, we characterized the microbial communities mediating the degradation of Chlorella vulgaris (Chlorophyta), Chara sp. strain IWP1 (Charophyceae), and kelp Ascophyllum nodosum (phylum Phaeophyceae), using sediments from an anaerobic spring (Zodlteone spring, OK; ZDT), sludge from a secondary digester in a local wastewater treatment plant (Stillwater, OK; WWT), and deeper anoxic layers from a seasonally stratified lake (Grand Lake O’ the Cherokees, OK; GL) as inoculum sources. Within all enrichments, the majority of algal biomass was metabolized within 13–16 weeks, and the process was accompanied by an increase in cell numbers and a decrease in community diversity. Community surveys based on the V4 region of the 16S rRNA gene identified different lineages belonging to the phyla Bacteroidetes, Proteobacteria (alpha, delta, gamma, and epsilon classes), Spirochaetes, and Firmicutes that were selectively abundant under various substrate and inoculum conditions. Within all kelp enrichments, the microbial communities structures at the conclusion of the experiment were highly similar regardless of the enrichment source, and were dominated by the genus Clostridium, or family Veillonellaceae within the Firmicutes. In all other enrichments the final microbial community was dependent on the inoculum source, rather than the type of algae utilized as substrate. Lineages enriched

  13. Density of states measurements in a p-i-n solar cell

    SciTech Connect

    Crandall, R.S.; Wang, Q.

    1996-05-01

    The authors describe results of density of states (DOS) profiling in p-i-n solar-cell devices using drive-level capacitance (DLC) techniques. Near the p-i interface the defect density is high, decreasing rapidly into the interior, reaching low values in the central region of the cell, and rising rapidly again at the n-i interface. They show that the states in the central region are neutral dangling-bond defects, whereas those near the interfaces with the doped layers are charged dangling bonds.

  14. Large-scale production of magnetosomes by chemostat culture of Magnetospirillum gryphiswaldense at high cell density

    PubMed Central

    2010-01-01

    Background Magnetotactic bacteria have long intrigued researchers because they synthesize intracellular nano-scale (40-100 nm) magnetic particles composed of Fe3O4, termed magnetosomes. Current research focuses on the molecular mechanisms of bacterial magnetosome formation and its practical applications in biotechnology and medicine. Practical applications of magnetosomes are based on their ferrimagnetism, nanoscale size, narrow size distribution, dispersal ability, and membrane-bound structure. However, the applications of magnetosomes have not yet been developed commercially, mainly because magnetotactic bacteria are difficult to cultivate and consistent, high yields of magnetosomes have not yet been achieved. Results We report a chemostat culture technique based on pH-stat feeding that yields a high cell density of Magnetospirillum gryphiswaldense strain MSR-1 in an auto-fermentor. In a large-scale fermentor, the magnetosome yield was significantly increased by adjusting the stirring rate and airflow which regulates the level of dissolved oxygen (DO). Low concentration of sodium lactate (2.3 mmol l-1) in the culture medium resulted in more rapid cell growth and higher magnetosome yield than high concentration of lactate (20 mmol l-1). The optical density of M. gryphiswaldense cells reached 12 OD565 nm after 36 hr culture in a 42 L fermentor. Magnetosome yield and productivity were 83.23 ± 5.36 mg l-1 (dry weight) and 55.49 mg l-1 day-1, respectively, which were 1.99 and 3.32 times higher than the corresponding values in our previous study. Conclusions Compared to previously reported methods, our culture technique with the MSR-1 strain significantly increased cell density, cell yield, and magnetosome yield in a shorter time window and thus reduced the cost of production. The cell density and magnetosome yield reported here are the highest so far achieved with a magnetotactic bacteria. Refinement of this technique will enable further increase of cell density and

  15. Regulation of Kv2.1 K+ conductance by cell surface channel density

    PubMed Central

    Fox, Philip D.; Loftus, Rob J.; Tamkun, Michael M.

    2013-01-01

    The Kv2.1 voltage-gated K+ channel is found both freely diffusing over the plasma membrane and concentrated in micron-sized clusters localized to the soma, proximal dendrites and axon initial segment of hippocampal neurons. In transfected HEK cells, Kv2.1 channels within cluster microdomains are non-conducting. Using TIRF microscopy the number of GFP-tagged Kv2.1 channels on the HEK cell surface was compared to K+ channel conductance measured by whole-cell voltage-clamp of the same cell. This approach indicated that as channel density increases non-clustered channels cease conducting. At the highest density observed, only 4% of all channels were conducting. Mutant Kv2.1 channels that fail to cluster also possessed the non-conducting state with 17% conducting K+ at higher surface densities. The non-conducting state was specific to Kv2.1 as Kv1.4 was always conducting regardless of the cell-surface expression level. Anti-Kv2.1 immuno-fluorescence intensity, standardized to Kv2.1 surface density in transfected HEK cells, was used to determine the expression levels of endogenous Kv2.1 in cultured rat hippocampal neurons. Endogenous Kv2.1 levels were compared to the number of conducting channels determined by whole-cell voltage clamp. Only 13 and 27% of the endogenous Kv2.1 was conducting in neurons cultured for 14 and 20 days, respectively. Together these data indicate that the non-conducting state depends primarily on surface density as opposed to cluster location and that this non-conducting state also exists for native Kv2.1 found in cultured hippocampal neurons. This excess of Kv2.1 protein relative to K+ conductance further supports a non-conducting role for Kv2.1 in excitable tissues. PMID:23325261

  16. Stimulation of limb cartilage differentiation by cyclic AMP is dependent on cell density.

    PubMed

    Rodgers, B J; Kulyk, W M; Kosher, R A

    1989-12-01

    Cyclic AMP (cAMP) has been implicated in the regulation of limb cartilage differentiation. This study represents an attempt to clarify potential mechanisms by which cAMP might regulate chondrogenesis. We have found that the ability of cAMP to stimulate limb cartilage differentiation in vitro is dependent on cell density. Dibutyryl cAMP (dbcAMP) elicits a striking increase in the accumulation of Alcian blue, pH 1.0-positive cartilage matrix, and a corresponding three- to fourfold increase in the accumulation of 35S-labeled glycosaminoglycans (GAG) by limb mesenchymal cells cultured in low serum medium at densities greater than confluence (i.e. micromass cultures established with 1-2 x 10(5) cells in 10 microliters of medium). Moreover, dbcAMP causes a striking (two- to fourfold) increase in the steady-state cytoplasmic levels of mRNAs for cartilage-characteristic type II collagen and the core protein of cartilage-specific sulfated proteoglycan in these high density, supraconfluent cultures. In contrast, cAMP does not promote the chondrogenesis of limb mesenchymal cells cultured at subconfluent densities (i.e. cultures initiated with 2.5-5 x 10(4) cells in 10 microliters of medium). In these low density cultures, dbcAMP does not promote the formation of cartilage matrix, sulfated GAG accumulation or the accumulation of cartilage-specific mRNAs. These observations suggest that cAMP may exert its regulatory effect in part by facilitating cell-cell communication during the critical condensation phase of chondrogenesis.

  17. Algal conditions in the Caloosahatchee River (1975-79), Lake Okeechobee to Franklin Lock, Florida

    USGS Publications Warehouse

    McPherson, Benjamin F.; La Rose, Henry R.

    1982-01-01

    Maximum numbers of suspended algae occurred in late spring and early summer, in each of the years 1975-79, in the Caloosahatchee River. Numbers exceeded 100,000 cells per milliliter at all stations sometime during the study. Concentrations decreased during late summer and autumn and were low during winter, except in January 1979 when numbers at most sites exceeded 100,000 cells per milliliter. The January 1979 bloom coincided with large discharges from Lake Okeechobee. During previous winters, discharges and algal numbers were lower. During other seasons, algal blooms occurred most frequently under low-flow or stagnant conditions. The upstream site at Moore Haven, which had the least discharge and was most stagnant, had consistently higher algal concentrations than downstream sites. Blue-green algae were dominant in the river during the summer at the upstream site throughout the year. The percentage of blue-green algae decreased downstream. Concentrations of nitrite plus nitrate nitrogen were inversely correlated with concentrations of algae and decreased to near zero during algal blooms. The low concentrations of these forms of inorganic nitrogen relative to other major nutrients probably favor blue-green algae and limit growth of other algae. Contributions by the basin tributaries to the nutritive condition of the river were small because concentrations of nutrients, algal growth potential, and algae in the tributaries were generally less than those in the river. (USGS)

  18. Problems related to water quality and algal control in Lopez Reservoir, San Luis Obispo County, California

    USGS Publications Warehouse

    Fuller, Richard H.; Averett, Robert C.; Hines, Walter G.

    1975-01-01

    A study to determine the present enrichment status of Liopez Reservoir in San Luis Obispo county, California, and to evaluate copper sulfate algal treatment found that stratification in the reservoir regulates nutrient release and that algal control has been ineffective. Nuisance algal blooms, particularly from March to June, have been a problem in the warm multipurpose reservoir since it was initially filled following intense storms in 1968-69. The cyanophyte Anabaena unispora has been dominant; cospecies are the diatoms Stephanodiscus astraea and Cyclotella operculata, and the chlorophytes Pediastrum deplex and Sphaerocystis schroeteri. During an A. unispora bloom in May 1972 the total lake surface cell count was nearly 100,000 cells/ml. Thermal stratification from late spring through autumn results in oxygen deficiency in the hypolimnion and metalimnion caused by bacterial oxidation of organic detritus. The anaerobic conditions favor chemical reduction of organic matter, which constitute 10-14% of the sediment. As algae die, sink to the bottom, and decompose, nutrients are released to the hypolimnion , and with the autumn overturn are spread to the epilimnion. Algal blooms not only hamper recreation, but through depletion of dissolved oxygen in the epilimnion may have caused periodic fishkills. Copper sulfate mixed with sodium citrate and applied at 1.10-1.73 lbs/acre has not significantly reduced algal growth; a method for determining correct dosage is presented. (Lynch-Wisconsin)

  19. Cell-Autonomous Regulation of Dendritic Spine Density by PirB.

    PubMed

    Vidal, George S; Djurisic, Maja; Brown, Kiana; Sapp, Richard W; Shatz, Carla J

    2016-01-01

    Synapse density on cortical pyramidal neurons is modulated by experience. This process is highest during developmental critical periods, when mechanisms of synaptic plasticity are fully engaged. In mouse visual cortex, the critical period for ocular dominance (OD) plasticity coincides with the developmental pruning of synapses. At this time, mice lacking paired Ig-like receptor B (PirB) have excess numbers of dendritic spines on L5 neurons; these spines persist and are thought to underlie the juvenile-like OD plasticity observed in adulthood. Here we examine whether PirB is required specifically in excitatory neurons to exert its effect on dendritic spine and synapse density during the critical period. In mice with a conditional allele of PirB (PirB(fl/fl)), PirB was deleted only from L2/3 cortical pyramidal neurons in vivo by timed in utero electroporation of Cre recombinase. Sparse mosaic expression of Cre produced neurons lacking PirB in a sea of wild-type neurons and glia. These neurons had significantly elevated dendritic spine density, as well as increased frequency of miniature EPSCs, suggesting that they receive a greater number of synaptic inputs relative to Cre(-) neighbors. The effect of cell-specific PirB deletion on dendritic spine density was not accompanied by changes in dendritic branching complexity or axonal bouton density. Together, results imply a neuron-specific, cell-autonomous action of PirB on synaptic density in L2/3 pyramidal cells of visual cortex. Moreover, they are consistent with the idea that PirB functions normally to corepress spine density and synaptic plasticity, thereby maintaining headroom for cells to encode ongoing experience-dependent structural change throughout life.

  20. Cell-Autonomous Regulation of Dendritic Spine Density by PirB

    PubMed Central

    2016-01-01

    Synapse density on cortical pyramidal neurons is modulated by experience. This process is highest during developmental critical periods, when mechanisms of synaptic plasticity are fully engaged. In mouse visual cortex, the critical period for ocular dominance (OD) plasticity coincides with the developmental pruning of synapses. At this time, mice lacking paired Ig-like receptor B (PirB) have excess numbers of dendritic spines on L5 neurons; these spines persist and are thought to underlie the juvenile-like OD plasticity observed in adulthood. Here we examine whether PirB is required specifically in excitatory neurons to exert its effect on dendritic spine and synapse density during the critical period. In mice with a conditional allele of PirB (PirBfl/fl), PirB was deleted only from L2/3 cortical pyramidal neurons in vivo by timed in utero electroporation of Cre recombinase. Sparse mosaic expression of Cre produced neurons lacking PirB in a sea of wild-type neurons and glia. These neurons had significantly elevated dendritic spine density, as well as increased frequency of miniature EPSCs, suggesting that they receive a greater number of synaptic inputs relative to Cre– neighbors. The effect of cell-specific PirB deletion on dendritic spine density was not accompanied by changes in dendritic branching complexity or axonal bouton density. Together, results imply a neuron-specific, cell-autonomous action of PirB on synaptic density in L2/3 pyramidal cells of visual cortex. Moreover, they are consistent with the idea that PirB functions normally to corepress spine density and synaptic plasticity, thereby maintaining headroom for cells to encode ongoing experience-dependent structural change throughout life. PMID:27752542

  1. CsCl Density Gradient Centrifugation Studies of Intact Bacterial Cells

    PubMed Central

    Pollard, Ernest C.; Grady, Leo J.

    1967-01-01

    Cells of Escherichia coli have been successfully banded in CsCl density gradients and a portion of the population reclaimed in a viable state. Differentiation between two strains of this organism in a CsCl density gradient has been demonstrated also. Several studies were undertaken to see whether differences could be detected between two samples of cells of the same strain which had been subjected to different conditions. The results were as follows: (a) Introduction of a heavy label (5-bromouracil) into the DNA during a 90 minute period did not produce an observable change in cell density. (b) Removal of a required amino acid from the growth medium of an E. coli auxotroph resulted in an increase in both the density and heterogeneity of the cells. (c) Exposure of cells to 27 kr of gamma radiation, followed by a period during which portions of both DNA and RNA were lost, yielded two distinct bands, one at the normal position in the gradient and the other shifted to a lighter region. PMID:4860484

  2. Experimental characterization of active acoustic metamaterial cell with controllable dynamic density

    NASA Astrophysics Data System (ADS)

    Akl, Wael; Baz, Amr

    2012-10-01

    Controlling wave propagation pattern within acoustic fluid domains has been the motivation for the acoustic metamaterials developments to target applications ranging from acoustic cloaking to passive noise control techniques. Currently, various numerical and analytical approaches exist to predict the fluid domain material properties necessary for specific propagation pattern. Physical attempts to realize such material properties have revealed engineered material constructions that are focused on predefined wave propagation patterns. In the current paper, coupled fluid-structure one-dimensional metamaterial cell, in which piezoelectric active ingredient has been introduced, is manufactured to achieve controllable dynamic density. The density-controllable cell has been manufactured by coupling a water-filled cavity with piezoelectric elements in a cell of 4.5 cm length and 4.1 cm diameter subject to impulse excitation. A finite element model of the cell has been developed and its predictions are validated against the experimental results. The validated model is utilized to predict the changes in the pressure gradient inside the developed cell which is a direct measure of the changes introduced to the dynamic density of the acoustic metamaterial domain. With such predictions, it is demonstrated that densities as high as 3.2 gm/cm3 and as low as 0.72 gm/cm3 can be achieved experimentally for excitation frequencies ranging between 100 Hz and 500 Hz.

  3. High cell density attenuates reactive oxygen species: implications for in vitro assays.

    PubMed

    Kim, Dennis P; Yahav, Jonathan; Sperandeo, Michael; Maloney, Lauren; McTigue, Monica; Lin, Fubao; Clark, Richard A F

    2012-01-01

    In vitro cell-based assays are an essential and universally used step in elucidation of biological processes as well as in drug development. However, results obtained depend on the validity of protocols used. This statement certainly pertains to in vitro assays of oxidative stress. The holy grail of in vitro models is reliability and predictability of outcomes that relate to a single variable like addition of hydrogen peroxide or xanthine oxidase. Without such validated outcomes, comparison of results among different laboratories is not possible. Achieving this goal requires a thorough understanding of the complex interplay between the cells, their environment, and the experimental assays. Furthermore, as this knowledge is attained, it must be disseminated and used to update and standardize existing protocols. Here, we confirm and extend the effect of pyruvate and cell density on in vitro oxidative stress assays. Cell viability was assessed using a colorimetric assay measuring the reduction of a tetrazolium salt (XTT) into a colored formazan dye. Extracellular hydrogen peroxide concentrations were measured using the foxp3 assay. We confirmed a previously reported finding that pyruvate, a common ingredient in cell culture media, acts as an extracellular scavenger of reactive oxygen species. We also demonstrated that cell density directly correlates with resistance to oxidative stress in tissue culture. It is theorized that the protective effect due to cell density predominantly relates to intracellular factors such as reduced glutathione and extracellular factors such as catalase.

  4. Algal Biology Toolbox Workshop Summary Report

    SciTech Connect

    None, None

    2016-08-01

    DOE-EERE's Bioenergy Technologies Office (BETO) works to accelerate the development of a sustainable, cost-competitive, advanced biofuel industry that can strengthen U.S. energy security, environmental quality, and economic vitality, through research, development, and demonstration projects in partnership with industry, academia, and national laboratory partners. BETO’s Advanced Algal Systems Program (also called the Algae Program) has a long-term applied research and development (R&D) strategy to increase the yields and lower the costs of algal biofuels. The team works with partners to develop new technologies, to integrate technologies at commercially relevant scales, and to conduct crosscutting analyses to better understand the potential and challenges of the algal biofuels industry. Research has indicated that this industry is capable of producing billions of gallons of renewable diesel, gasoline, and jet fuels annually. R&D activities are integrated with BETO’s longstanding effort to accelerate the commercialization of lignocellulosic biofuels.

  5. Critical evaluation and modeling of algal harvesting using dissolved air flotation. DAF Algal Harvesting Modeling

    SciTech Connect

    Zhang, Xuezhi; Hewson, John C.; Amendola, Pasquale; Reynoso, Monica; Sommerfeld, Milton; Chen, Yongsheng; Hu, Qiang

    2014-07-14

    In our study, Chlorella zofingiensis harvesting by dissolved air flotation (DAF) was critically evaluated with regard to algal concentration, culture conditions, type and dosage of coagulants, and recycle ratio. Harvesting efficiency increased with coagulant dosage and leveled off at 81%, 86%, 91%, and 87% when chitosan, Al3+, Fe3+, and cetyl trimethylammonium bromide (CTAB) were used at dosages of 70, 180, 250, and 500 mg g-1, respectively. The DAF efficiency-coagulant dosage relationship changed with algal culture conditions. In evaluating the influence of the initial algal concentration and recycle ratio revealed that, under conditions typical for algal harvesting, we found that it is possible that the number of bubbles is insufficient. A DAF algal harvesting model was developed to explain this observation by introducing mass-based floc size distributions and a bubble limitation into the white water blanket model. Moreover, the model revealed the importance of coagulation to increase floc-bubble collision and attachment, and the preferential interaction of bubbles with larger flocs, which limited the availability of bubbles to the smaller sized flocs. The harvesting efficiencies predicted by the model agree reasonably with experimental data obtained at different Al3+ dosages, algal concentrations, and recycle ratios. Based on this modeling, critical parameters for efficient algal harvesting were identified.

  6. Critical evaluation and modeling of algal harvesting using dissolved air flotation. DAF Algal Harvesting Modeling

    DOE PAGES

    Zhang, Xuezhi; Hewson, John C.; Amendola, Pasquale; ...

    2014-07-14

    In our study, Chlorella zofingiensis harvesting by dissolved air flotation (DAF) was critically evaluated with regard to algal concentration, culture conditions, type and dosage of coagulants, and recycle ratio. Harvesting efficiency increased with coagulant dosage and leveled off at 81%, 86%, 91%, and 87% when chitosan, Al3+, Fe3+, and cetyl trimethylammonium bromide (CTAB) were used at dosages of 70, 180, 250, and 500 mg g-1, respectively. The DAF efficiency-coagulant dosage relationship changed with algal culture conditions. In evaluating the influence of the initial algal concentration and recycle ratio revealed that, under conditions typical for algal harvesting, we found that itmore » is possible that the number of bubbles is insufficient. A DAF algal harvesting model was developed to explain this observation by introducing mass-based floc size distributions and a bubble limitation into the white water blanket model. Moreover, the model revealed the importance of coagulation to increase floc-bubble collision and attachment, and the preferential interaction of bubbles with larger flocs, which limited the availability of bubbles to the smaller sized flocs. The harvesting efficiencies predicted by the model agree reasonably with experimental data obtained at different Al3+ dosages, algal concentrations, and recycle ratios. Based on this modeling, critical parameters for efficient algal harvesting were identified.« less

  7. Algal Accessory Pigment Detection Using AVIRIS Image-Derived Spectral Radiance Data

    NASA Technical Reports Server (NTRS)

    Richardson, Laurie L.; Ambrosia, Vincent G.

    1996-01-01

    Visual and derivative analyses of AVIRIS spectral data can be used to detect algal accessory pigments in aquatic communities. This capability extends the use of remote sensing for the study of aquatic ecosystems by allowing detection of taxonomically significant pigment signatures which yield information about the type of algae present. Such information allows remote sensing-based assessment of aquatic ecosystem health, as in the detection of nuisance blooms of cyanobacteria or toxic blooms of dinoflagellates. Remote sensing of aquatic systems has traditionally focused on quantification of chlorophyll a, a photoreactive (and light-harvesting) pigment which is common to all algae as well as cyanobacteria (bluegreen algae). Due to the ubiquitousness of this pigment within algae, chl a is routinely measured to estimate algal biomass both during ground-truthing and using various airborne or satellite based sensors, including AVIRIS. Within the remote sensing and aquatic sciences communities, ongoing research has been performed to detect algal accessory pigments for assessment of algal population composition. This research is based on the fact that many algal accessory pigments are taxonomically significant, and all are spectrally unique. Aquatic scientists have been refining pigment analysis techniques, primarily high performance liquid chromatography, or HPLC, to detect specific pigments as a time-saving alternative to individual algal cell identifications and counts. Remote sensing scientists are investigating the use of pigment signatures to construct pigment libraries analogous to mineral spectral libraries used in geological remote sensing applications. The accessory pigment approach has been used successfully in remote sensing using data from the Thematic Mapper, low-altitude, multiple channel scanners, field spectroradiometers and the AVIRIS hyperspectral scanner. Due to spectral and spatial resolution capabilities, AVIRIS is the sensor of choice for such

  8. The effect of cell size and channel density on neuronal information encoding and energy efficiency.

    PubMed

    Sengupta, Biswa; Faisal, A Aldo; Laughlin, Simon B; Niven, Jeremy E

    2013-09-01

    Identifying the determinants of neuronal energy consumption and their relationship to information coding is critical to understanding neuronal function and evolution. Three of the main determinants are cell size, ion channel density, and stimulus statistics. Here we investigate their impact on neuronal energy consumption and information coding by comparing single-compartment spiking neuron models of different sizes with different densities of stochastic voltage-gated Na(+) and K(+) channels and different statistics of synaptic inputs. The largest compartments have the highest information rates but the lowest energy efficiency for a given voltage-gated ion channel density, and the highest signaling efficiency (bits spike(-1)) for a given firing rate. For a given cell size, our models revealed that the ion channel density that maximizes energy efficiency is lower than that maximizing information rate. Low rates of small synaptic inputs improve energy efficiency but the highest information rates occur with higher rates and larger inputs. These relationships produce a Law of Diminishing Returns that penalizes costly excess information coding capacity, promoting the reduction of cell size, channel density, and input stimuli to the minimum possible, suggesting that the trade-off between energy and information has influenced all aspects of neuronal anatomy and physiology.

  9. BDNF over-expression increases olfactory bulb granule cell dendritic spine density in vivo

    PubMed Central

    McDole, Brittnee; Isgor, Ceylan; Pare, Christopher; Guthrie, Kathleen

    2015-01-01

    Olfactory bulb granule cells are axon-less, inhibitory interneurons that regulate the activity of the excitatory output neurons, the mitral and tufted cells, through reciprocal dendrodendritic synapses located on granule cell spines. These contacts are established in the distal apical dendritic compartment, while granule cell basal dendrites and more proximal apical segments bear spines that receive glutamatergic inputs from the olfactory cortices. This synaptic connectivity is vital to olfactory circuit function and is remodeled during development, and in response to changes in sensory activity and lifelong granule cell neurogenesis. Manipulations that alter levels of the neurotrophin brain-derived neurotrophic factor (BDNF) in vivo have significant effects on dendritic spine morphology, maintenance and activity-dependent plasticity for a variety of CNS neurons, yet little is known regarding BDNF effects on bulb granule cell spine maturation or maintenance. Here we show that, in vivo, sustained bulbar over-expression of BDNF produces a marked increase in granule cell spine density that includes an increase in mature spines on their apical dendrites. Morphometric analysis demonstrated that changes in spine density were most notable in the distal and proximal apical domains, indicating that multiple excitatory inputs are potentially modified by BDNF. Our results indicate that increased levels of endogenous BDNF can promote the maturation and/or maintenance of dendritic spines on granule cells, suggesting a role for this factor in modulating granule cell functional connectivity within adult olfactory circuitry. PMID:26211445

  10. Mapping the polarity and stimulus density requirements for T-cell activation

    NASA Astrophysics Data System (ADS)

    Wei, Xunbin; Krasieva, Tatiana B.; Zhang, Zhanxiang; Negulescu, Paul A.; Sun, Chung-Ho; Berns, Michael W.; Cahalan, Michael D.; Tromberg, Bruce J.

    1998-08-01

    T-cell contact with antigen-presenting cells (APC) initiates an activation cascade which includes an increase in T-cell intracellular calcium [(Ca2+)i] and leads to T-cell proliferation and differentiation. Although T-cell/APC physical contact is required for an immune response, little is known about the patterns of cellular interaction and their relation to activation. We have combined fluorescence spectroscopy and imaging with optical manipulation to investigate the contact requirements for T-cell activation, using optical tweezers to control the orientation of T- cell/APC pairs and fluorescence microscopy to measure the subsequent (Ca2+)i response, detected as an emission shift from the combination of fura-red and oregon- green, two cytoplasmic (Ca2+) indicators. APCs or beads coated with antibodies to the T-cell receptor (TCR) are trapped with a near-infrared titanium-sapphire laser and placed at different locations along the T-cell, which has a polarized appearance defined by the shape and direction of crawling (2-5 micrometers /min). T cells contacted with antigen- presenting cells or antibody-coated beads entered a dynamic and reproducible program in the first 10 - 20 mins, including (Ca2+)i increase, changes in shape and motility, engulfment, and stable contact. T cells presented with antigen at the leading edge had a higher probability of responding (85%) and a shorter latency of response (50 secs) than those contacting APCs or beads with their trailing end (APCs: 30%, 150 secs; beads: 6%, 300 secs). Alterations in antibody density, quantified by FACS analysis, and bead size were used to determine the spatial requirements for T cell activation and the minimum number of receptors which must be engaged in order to transmit a positive signal. Preliminary data show that T cell responses [response percentage, latency and (Ca2+)i pattern] depend on both antibody density and bead size.

  11. Quantitative control of active targeting of nanocarriers to tumor cells through optimization of folate ligand density.

    PubMed

    Tang, Zhaomin; Li, Dan; Sun, Huili; Guo, Xing; Chen, Yuping; Zhou, Shaobing

    2014-09-01

    The active targeting delivery system has been widely studied in cancer therapy by utilizing folate (FA) ligands to generate specific interaction between nanocarriers and folate receptors (FRs) on tumor cell. However, there is little work that has been published to investigate the influence of the definite density of the FA ligands on the active targeting of nanocarriers. In this study, we have combined magnetic-guided iron oxide nanoparticles with FA ligands, adjusted the FA ligand density and then studied the resulting effects on the active targeting ability of this dual-targeting drug delivery system to tumor cells. We have also optimized the FA ligand density of the drug delivery system for their active targeting to FR-overexpressing tumor cells in vitro. Prussian blue staining, semi-thin section of cells observed with transmission electron microscopy (TEM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) have shown that the optimal FA density is from 2.3 × 10(18) to 2.5 × 10(18) per gram nanoparticles ((g·NPs)(-1)). We have further tried to qualitatively and quantitatively control the active targeting and delivering of drugs to tumors on 4T1-bearing BALB/c mice. As expected, the in vivo experimental results have also demonstrated that the FA density of the magnetic nanoparticles (MNPs) could be optimized for a more easily binding to tumor cells via the multivalent linkages and more readily internalization through the FR-mediated endocytosis. Our study can provide a strategy to quantitatively control the active targeting of nanocarriers to tumor cells for cancer therapy.

  12. Harmful Algal Blooms – Special Sampling and Response Actions

    EPA Pesticide Factsheets

    The Harmful Algal Blooms – Special Sampling and Response Actions webpage contains information about Background on Harmful Algae in Surface Waters and What to Do if Your System Has Indicators of an Algal Bloom.

  13. Relevance of density, size and DNA content of tumour cells to the lung colony assay.

    PubMed Central

    Grdina, D. J.; Hittelman, W. N.; White, R. A.; Meistrich, M. L.

    1977-01-01

    Mouse fibrosarcoma tumours were dissociated and divided into subpopulations of viable cells by centrifugation in linear density gradients of Renografin. Two of these subpopulations, designated Band 2 and Band 4, differed in their clonogenic ability in lung colony assay. The less dense Band 2 cells were significantly more clonogenic than the Band 4 cells (2.9 percent vs 1.4 percent respectively). Each band was further separated on the basis of cell size by centrifugal elutriation. Each size class of cells comprising Band 2 showed higher clonogenic ability than the corresponding size class in Band 4. Thus cell size differences were not responsible for the clonogenic differences between these bands. To determine whether cell-cycle distribution of the tumour cells was responsible for differences in cloning efficiency, flow microfluorometric and premature chromosome condensation methods were utilized. The unseparated and Band 4 populations showed a higher percentage of cells in S and G2 than did the Band 2 populations, but many of the S and G2 tumour cells showed extensive chromosome damage. From this study we conclude that the increased clonogenic ability of the lighter tumour cells is not due to differences in cell size or cell-cycle parameters. Images Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:563726

  14. Density-based separation in multiphase systems provides a simple method to identify sickle cell disease

    PubMed Central

    Kumar, Ashok A.; Patton, Matthew R.; Hennek, Jonathan W.; Lee, Si Yi Ryan; D’Alesio-Spina, Gaetana; Yang, Xiaoxi; Kanter, Julie; Shevkoplyas, Sergey S.; Brugnara, Carlo; Whitesides, George M.

    2014-01-01

    Although effective low-cost interventions exist, child mortality attributable to sickle cell disease (SCD) remains high in low-resource areas due, in large part, to the lack of accessible diagnostic methods. The presence of dense (ρ > 1.120 g/cm3) cells is characteristic of SCD. The fluid, self-assembling step-gradients in density created by aqueous multiphase systems (AMPSs) identifies SCD by detecting dense cells. AMPSs separate different forms of red blood cells by density in a microhematocrit centrifuge and provide a visual means to distinguish individuals with SCD from those with normal hemoglobin or with nondisease, sickle-cell trait in under 12 min. Visual evaluation of a simple two-phase system identified the two main subclasses of SCD [homozygous (Hb SS) and heterozygous (Hb SC)] with a sensitivity of 90% (73–98%) and a specificity of 97% (86–100%). A three-phase system identified these two types of SCD with a sensitivity of 91% (78–98%) and a specificity of 88% (74–98%). This system could also distinguish between Hb SS and Hb SC. To the authors’ knowledge, this test demonstrates the first separation of cells by density with AMPSs, and the usefulness of AMPSs in point-of-care diagnostic hematology. PMID:25197072

  15. Maximizing the power density of aqueous electrochemical flow cells with in operando deposition

    NASA Astrophysics Data System (ADS)

    Goulet, Marc-Antoni; Ibrahim, Omar A.; Kim, Will H. J.; Kjeang, Erik

    2017-01-01

    To transition toward sustainable energy systems, next generation power sources must provide high power density at minimum cost. Using inexpensive and environmentally friendly fabrication methods, this work describes a room temperature electrochemical flow cell with a maximum power density of 2.01 W cm-2 or 13.4 W cm-3. In part, this is achieved by minimizing ohmic resistance through decreased electrode spacing, implementation of current collectors and improvement of electrolyte conductivity. The majority of the performance gain is provided by a novel in operando dynamic flowing deposition method for which the cell design has been optimized. Carbon nanotubes (CNTs) are deposited dynamically at the entrance of and within the carbon paper electrodes during operation of the cell. A natural equilibrium is reached between deposition and detachment of CNTs at which the electrochemical surface area and pore size distribution of the flow-through porous electrodes are greatly enhanced. In this way, the novel deposition method more than doubles the power density of the cell and sets a new performance benchmark for what is practically attainable with aqueous electrochemical flow cells. Overall, it is expected that the design and operation methods illustrated here will enable a wide range of electrochemical flow cell technologies to achieve optimal performance.

  16. Density measurement of samples under high pressure using synchrotron microtomography and diamond anvil cell techniques

    PubMed Central

    Xiao, Xianghui; Liu, Haozhe; Wang, Luhong; De Carlo, Francesco

    2010-01-01

    Accurate mass density information is critical in high-pressure studies of materials. It is, however, very difficult to measure the mass densities of amorphous materials under high pressure with a diamond anvil cell (DAC). Employing tomography to measure mass density of amorphous samples under high pressure in a DAC has recently been reported. In reality, the tomography data of a sample in a DAC suffers from not only noise but also from the missing angle problem owing to the geometry of the DAC. An algorithm that can suppress noise and overcome the missing angle problem has been developed to obtain accurate mass density information from such ill-posed data. The validity of the proposed methods was supported with simulations. PMID:20400834

  17. Method of Fabrication of High Power Density Solid Oxide Fuel Cells

    DOEpatents

    Pham, Ai Quoc; Glass, Robert S.

    2008-09-09

    A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O(LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.

  18. Ultrasonic density measurement cell design and simulation of non-ideal effects.

    PubMed

    Higuti, Ricardo Tokio; Buiochi, Flávio; Adamowski, Júlio Cezar; de Espinosa, Francisco Montero

    2006-07-01

    This paper presents a theoretical analysis of a density measurement cell using an unidimensional model composed by acoustic and electroacoustic transmission lines in order to simulate non-ideal effects. The model is implemented using matrix operations, and is used to design the cell considering its geometry, materials used in sensor assembly, range of liquid sample properties and signal analysis techniques. The sensor performance in non-ideal conditions is studied, considering the thicknesses of adhesive and metallization layers, and the effect of residue of liquid sample which can impregnate on the sample chamber surfaces. These layers are taken into account in the model, and their effects are compensated to reduce the error on density measurement. The results show the contribution of residue layer thickness to density error and its behavior when two signal analysis methods are used.

  19. Effect of Methionine Restriction on Bone Density and NK Cell Activity

    PubMed Central

    Dong, Jingming

    2016-01-01

    Methionine restriction (MR) is proven to increase the lifespan; and it also affects the bone density and the innate immune system. The aim of this study is to explore the effect of methionine restriction on bone density and natural killer (NK) cells. C57BL/6J mice were subjected to either basal diet (BD, containing 0.80% methionine) or methionine-restricted diet (containing 0.14% methionine). Mice with MR diet displayed reduced bone mass and decrease in the cytotoxicity of NK from the spleen, compared to BD animals. Also, mice with MR diet had an inferior body weight (P < 0.05) and higher plasma levels of adiponectin and FGF21 (P < 0.05) but lower concentrations of leptin and IGF-1 (P < 0.05). Overall, the investigation shows that methionine affects bone density and NK cell cytotoxicity. PMID:27882323

  20. Collagen density regulates xenobiotic and hypoxic response of mammary epithelial cells.

    PubMed

    Curran, Colleen S; Carrillo, Esteban R; Ponik, Suzanne M; Keely, Patricia J

    2015-01-01

    Breast density, where collagen I is the dominant component, is a significant breast cancer risk factor. Cell surface integrins interact with collagen, activate focal adhesion kinase (FAK), and downstream cell signals associated with xenobiotics (AhR, ARNT) and hypoxia (HIF-1α, ARNT). We examined if mammary cells cultured in high density (HD) or low density (LD) collagen gels affected xenobiotic or hypoxic responses. ARNT production was significantly reduced by HD culture and in response to a FAK inhibitor. Consistent with a decrease in ARNT, AhR and HIF-1α reporter activation and VEGF production was lower in HD compared to LD. However, P450 production was enhanced in HD and induced by AhR and HIF-1α agonists, possibly in response to increased NF-κB activaton. Thus, collagen density differentially regulates downstream cell signals of AhR and HIF-1α by modulating the activity of FAK, the release of NF-κB transcriptional factors, and the levels of ARNT.

  1. A KINETIC MODEL FOR CELL DENSITY DEPENDENT BACTERIAL TRANSPORT IN POROUS MEDIA

    EPA Science Inventory

    A kinetic transport model with the ability to account for variations in cell density of the aqueous and solid phases was developed for bacteria in porous media. Sorption kinetics in the advective-dispersive-sorptive equation was described by assuming that adsorption was proportio...

  2. Collagen density regulates xenobiotic and hypoxic response of mammary epithelial cells

    PubMed Central

    Curran, Colleen S.; Carrillo, Esteban R.; Ponik, Suzanne M.; Keely, Patricia J.

    2014-01-01

    Breast density, where collagen I is the dominant component, is a significant breast cancer risk factor. Cell surface integrins interact with collagen, activate focal adhesion kinase (FAK), and downstream cell signals associated with xenobiotics (AhR, ARNT) and hypoxia (HIF-1α, ARNT). We examined if mammary cells cultured in high density (HD) or low density (LD) collagen gels affected xenobiotic or hypoxic responses. ARNT production was significantly reduced by HD culture and in response to a FAK inhibitor. Consistent with a decrease in ARNT, AhR and HIF-1α reporter activation and VEGF production was lower in HD compared to LD. However, P450 production was enhanced in HD and induced by AhR and HIF-1α agonists, possibly in response to increased NF-kB activaton. Thus, collagen density differentially regulates downstream cell signals of AhR and HIF-1α by modulating the activity of FAK, the release of NF-kB transcriptional factors, and the levels of ARNT. PMID:25481308

  3. Dietary guidance normalizes large intestinal endocrine cell densities in patients with irritable bowel syndrome

    PubMed Central

    Mazzawi, T; Hausken, T; Gundersen, D; El-Salhy, M

    2016-01-01

    Background/Objectives: To determine the large intestinal endocrine cell types affected following dietary guidance in patients with irritable bowel syndrome (IBS). Subjects/Methods: The study included 13 IBS patients and 13 control subjects. The patients received three sessions of individualized dietary guidance. Both the control subjects and the patients were scheduled for colonoscopies at baseline and again for the patients at 3–9 months after dietary guidance. Biopsy samples were taken from the colon and rectum and were immunostained for all types of large intestinal endocrine cells. The endocrine cells were quantified using computerized image analysis. Results: The daily total consumption (mean±s.e.m. values) of fruits and vegetables rich in FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) decreased significantly from 16.2±5.3 g before receiving dietary guidance to 9.2±3.2 g after receiving dietary guidance (P=0.02). In the total colon, the densities of serotonin cells were 46.8±8.9, 10.5±2.1 and 22.6±3.2 cells/mm2 in control subjects and in IBS patients before and after receiving dietary guidance, respectively (P=0.007); the corresponding densities of peptide YY cells were 11.6±1.8, 10.8±1.7 and 16.8±2.1 cells/mm2, respectively (P=0.06). The cell densities for both serotonin and peptide YY did not change significantly in the rectum. The densities of somatostatin cells in the rectum were 13.5±3.0, 13.2±3.0, and 22.3±3.2 cells/mm2 for control subjects and for IBS patients before and after receiving dietary guidance, respectively (P=0.01). Conclusions: The densities of the large intestinal endocrine cells tend to normalize following dietary guidance that may have contributed to the improvement of the patients with IBS symptoms. PMID:26603880

  4. On-line near infrared bioreactor monitoring of cell density and concentrations of glucose and lactate during insect cell cultivation.

    PubMed

    Qiu, Jiang; Arnold, Mark A; Murhammer, David W

    2014-03-10

    Near infrared spectroscopy is demonstrated as a suitable method for monitoring real time cell density and concentrations of glucose and lactate during insect cell cultivation. The utility of this approach is illustrated during the cultivation of Trichoplusia ni BTI-Tn-5B1-4 insect cells in a stirred-tank bioreactor. On-line near infrared measurements are made by passing unaltered culture medium through an autoclavable near infrared flow-through sample cell during the cultivation process. Single-beam near infrared spectra were collected over the combination spectral range (5000-4000cm(-1)) through a 1.5mm path length sample. Cell density calibration model was established by uni-variable linear regressions with measured mean absorbance values of on-line spectra collected during a cultivation run. Calibration models are generated for glucose and lactate by regression analysis of both off line and on line spectra collected during a series of pre-measurement cultivation runs. Analyte-specific calibration models are generated by using a combination of spectra from both natural, unaltered samples and samples spiked with known levels of glucose and lactate. Spiked samples are used to destroy concentration correlations between solutes, thereby enhancing the selectivity of the calibration models. Absorbance spectra are used to build partial least squares calibration models for glucose and lactate. The calibration model for cell density corresponds to a univariate linear regression calibration model based on the mean absorbance between 4750 and 4250cm(-1). The standard errors of prediction are 1.54mM, 0.83mM, and 0.38×10(6)cells/mL for the glucose, lactate, and cell density models, respectively.

  5. Location and Density of Immune Cells in Precursor Lesions and Cervical Cancer.

    PubMed

    Bedoya, Astrid M; Jaramillo, Roberto; Baena, Armando; Castaño, Jorge; Olaya, Natalia; Zea, Arnold H; Herrero, Rolando; Sanchez, Gloria I

    2013-04-01

    Only a small proportion of women infected with Human Papillomavirus (HPV) develop cervical cancer. Host immune response seems to play a role eliminating the viral infection and preventing progression to cancer. Characterization of tumor infiltrating lymphocytes (TILs) in cervical pre-neoplastic lesions and cervical cancer may be helpful to understand the mechanisms that mediate this protection. The aim of this study was to determine if there are differences in the localization and density (cells/mm(2)) of CD8+ T-cells, CD4+ T-cells and Tregs (CD25 + Foxp3+) in cervical pre-neoplastic lesions and cervical cancer. Immunohistochemical analysis of sections of 96 (26 CIN1, 21 CIN2, 25 CIN3, and 24 SCC) samples revealed that regardless of CIN grades, CD8+ T-cells are more abundant than CD4+, CD25+ and Foxp3+ cells in both the stroma and epithelium. There was a higher density of CD8+ cells in the stroma of cervical cancer compared to CIN3 (OR = 4.20, 95% CI 1.2-15), CIN2 (OR = 7.86, 95% CI 1.7-36.4) and CIN1 (OR = 4.25, 95% CI 1.1-17). Studies evaluating whether these cells are recruited before or after cancer progression will be helpful to understand the role of these cells in the natural history of HPV-induced lesions.

  6. Ultrasonic disruption of algae cells

    NASA Astrophysics Data System (ADS)

    King, P. M.; Nowotarski, K.; Joyce, E. M.; Mason, T. J.

    2012-05-01

    During last decade there has been increasing interest in the production of sustainable fuels from microalgae (R.H. Wijffels and M.J. Barbosa, 2010; Singh et al 2011; D.H. Lee 2011). The aim of this project was to determine if algal cells can be ultrasonically disrupted to release lipids for biofuel production. Ultrasonic disruption of two unicellular algal species: Dunnaliella salina and Nannochloropsis oculata was investigated using a 20 kHz probe. Haemocytometer, optical density, UV-Vis, fluoro-spectrophotometer and confocal microscopy results demonstrated complete cell destruction of Dunaliella salina within 16 minutes of sonication. Results obtained for Nannochloropsis oculata differed in that ultrasound dispersed clumped cells with little or no cell disruption, as observed by haemocytometer and confocal microscopy analysis. However, UV-Visible and fluoro-spectrophotometer analysis indicated chlorophyll release following sonication, suggesting some cell disruption had occurred.

  7. Phycoremediation coupled production of algal biomass, harvesting and anaerobic digestion: possibilities and challenges.

    PubMed

    Prajapati, Sanjeev Kumar; Kaushik, Prachi; Malik, Anushree; Vijay, Virendra Kumar

    2013-12-01

    Biogas produced from anaerobic digestion is a versatile and environment friendly fuel which traditionally utilizes cattle dung as the substrate. In the recent years, owing to its high content of biodegradable compounds, algal biomass has emerged as a potential feedstock for biogas production. Moreover, the ability of algae to treat wastewater and fix CO2 from waste gas streams makes it an environmental friendly and economically feasible feedstock. The present review focuses on the possibility of utilizing wastewater as the nutrient and waste gases as the CO2 source for algal biomass production and subsequent biogas generation. Studies describing the various harvesting methods of algal biomass as well as its anaerobic digestion have been compiled and discussed. Studies targeting the most recent advancements on biogas enrichment by algae have been discussed. Apart from highlighting the various advantages of utilizing algal biomass for biogas production, limitations of the process such as cell wall resistivity towards digestion and inhibitions caused due to ammonia toxicity and the possible strategies for overcoming the same have been reviewed. The studies compiled in the present review indicate that if the challenges posed in translating the lab scale studies on phycoremediation and biogas production to pilot scale are overcome, algal biogas could become the sustainable and economically feasible source of renewable energy.

  8. Recycling produced water for algal cultivation for biofuels

    SciTech Connect

    Neal, Justin N.; Sullivan, Enid J.; Dean, Cynthia A.; Steichen, Seth A.

    2012-08-09

    Algal growth demands a continuous source of water of appropriate salinity and nutritional content. Fresh water sources are scarce in the deserts of the Southwestern United States, hence, salt water algae species are being investigated as a renewable biofuel source. The use of produced water from oil wells (PW) could offset the demand for fresh water in cultivation. Produced water can contain various concentrations of dissolved solids, metals and organic contaminants and often requires treatment beyond oil/water separation to make it suitable for algae cultivation. The produced water used in this study was taken from an oil well in Jal, New Mexico. An F/2-Si (minus silica) growth media commonly used to cultivate Nannochloropsis salina 1776 (NS 1776) was prepared using the produced water (F/2-Si PW) taking into account the metals and salts already present in the water. NS 1776 was seeded into a bioreactor containing 5L of the (F/2-Si PW) media. After eleven days the optical density at 750 nm (an indicator of algal growth) increased from 0 to 2.52. These results indicate algae are able to grow, though inhibited when compared with non-PW media, in the complex chemical conditions found in produced water. Savings from using nutrients present in the PW, such as P, K, and HCO{sub 3}{sup -}, results in a 44.38% cost savings over fresh water to mix the F/2-Si media.

  9. Cell Seeding Densities in Autologous Chondrocyte Implantation Techniques for Cartilage Repair.

    PubMed

    Foldager, Casper Bindzus; Gomoll, Andreas H; Lind, Martin; Spector, Myron

    2012-04-01

    Cartilage repair techniques have been among the most intensively investigated treatments in orthopedics for the past decade, and several different treatment modalities are currently available. Despite the extensive research effort within this field, the generation of hyaline cartilage remains a considerable challenge. There are many parameters attendant to each of the cartilage repair techniques that can affect the amount and types of reparative tissue generated in the cartilage defect, and some of the most fundamental of these parameters have yet to be fully investigated. For procedures in which in vitro-cultured autologous chondrocytes are implanted under a periosteal or synthetic membrane cover, or seeded onto a porous membrane or scaffold, little is known about how the number of cells affects the clinical outcome. Few published clinical studies address the cell seeding density that was employed. The principal objective of this review is to provide an overview of the cell seeding densities used in cell-based treatments currently available in the clinic for cartilage repair. Select preclinical studies that have informed the use of specific cell seeding densities in the clinic are also discussed.

  10. A High Power-Density, Mediator-Free, Microfluidic Biophotovoltaic Device for Cyanobacterial Cells

    PubMed Central

    Bombelli, Paolo; Müller, Thomas; Herling, Therese W; Howe, Christopher J; Knowles, Tuomas P J

    2015-01-01

    Biophotovoltaics has emerged as a promising technology for generating renewable energy because it relies on living organisms as inexpensive, self-repairing, and readily available catalysts to produce electricity from an abundant resource: sunlight. The efficiency of biophotovoltaic cells, however, has remained significantly lower than that achievable through synthetic materials. Here, a platform is devised to harness the large power densities afforded by miniaturized geometries. To this effect, a soft-lithography approach is developed for the fabrication of microfluidic biophotovoltaic devices that do not require membranes or mediators. Synechocystis sp. PCC 6803 cells are injected and allowed to settle on the anode, permitting the physical proximity between cells and electrode required for mediator-free operation. Power densities of above 100 mW m-2 are demonstrated for a chlorophyll concentration of 100 μM under white light, which is a high value for biophotovoltaic devices without extrinsic supply of additional energy. PMID:26190957

  11. Multi-stage continuous high cell density culture systems: a review.

    PubMed

    Chang, Ho Nam; Jung, Kwonsu; Choi, Jin-Dal-Rae; Lee, Joon Chul; Woo, Hee-Chul

    2014-01-01

    A multi-stage continuous high cell density culture (MSC-HCDC) system makes it possible to achieve high productivity together with high product titer of many bioproducts. For long-term continuous operation of MSC-HCDC systems, the cell retention time and hydraulic retention time must be decoupled and strains (bacteria, yeast, plant, and animal cells) must be stable. MSC-HCDC systems are suitable for low-value high-volume extracellular products such as fuel ethanol, lactic acid or volatile fatty acids, and high-value products such as monoclonal antibodies as well as intracellular products such as polyhydroxybutyric acid (PHB), microbial lipids or a number of therapeutics. Better understanding of the fermentation kinetics of a specific product and reliable high-density culture methods for the product-generating microorganisms will facilitate timely industrialization of MSC-HCDC systems for products that are currently obtained in fed-batch bioreactors.

  12. The role of oxygen in yeast metabolism during high cell density brewery fermentations.

    PubMed

    Verbelen, P J; Saerens, S M G; Van Mulders, S E; Delvaux, F; Delvaux, F R

    2009-04-01

    The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e., higher inoculum size). However, the decreased yeast net growth observed in these high cell density fermentations can have a negative impact on the physiological stability throughout subsequent yeast generations. The use of different oxygen conditions (wort aeration, wort oxygenation, yeast preoxygenation) was investigated to improve the growth yield during high cell density fermentations and yeast metabolic and physiological parameters were assessed systematically. Together with a higher extent of growth (dependent on the applied oxygen conditions), the fermentation power and the formation of unsaturated fatty acids were also affected. Wort oxygenation had a significant decreasing effect on the formation of esters, which was caused by a decreased expression of the alcohol acetyl transferase gene ATF1, compared with the other conditions. Lower glycogen and trehalose levels at the end of fermentation were observed in case of the high cell density fermentations with oxygenated wort and the reference fermentation. The expression levels of BAP2 (encoding the branched chain amino acid permease), ERG1 (encoding squalene epoxidase), and the stress responsive gene HSP12 were predominantly influenced by the high cell concentrations, while OLE1 (encoding the fatty acid desaturase) and the oxidative stress responsive genes SOD1 and CTT1 were mainly affected by the oxygen availability per cell. These results demonstrate that optimisation of high cell density fermentations could be achieved by improving the oxygen conditions, without drastically affecting the physiological condition of the yeast and beer quality.

  13. The reasons for the high power density of fuel cells fabricated with directly deposited membranes

    NASA Astrophysics Data System (ADS)

    Vierrath, Severin; Breitwieser, Matthias; Klingele, Matthias; Britton, Benjamin; Holdcroft, Steven; Zengerle, Roland; Thiele, Simon

    2016-09-01

    In a previous study, we reported that polymer electrolyte fuel cells prepared by direct membrane deposition (DMD) produced power densities in excess of 4 W/cm2. In this study, the underlying origins that give rise to these high power densities are investigated and reported. The membranes of high power, DMD-fabricated fuel cells are relatively thin (12 μm) compared to typical benchmark, commercially available membranes. Electrochemical impedance spectroscopy, at high current densities (2.2 A/cm2) reveals that mass transport resistance was half that of reference, catalyst-coated-membranes (CCM). This is attributed to an improved oxygen supply in the cathode catalyst layer by way of a reduced propensity of flooding, and which is facilitated by an enhancement in the back diffusion of water from cathode to anode through the thin directly deposited membrane. DMD-fabricated membrane-electrode-assemblies possess 50% reduction in ionic resistance (15 mΩcm2) compared to conventional CCMs, with contributions of 9 mΩcm2 for the membrane resistance and 6 mΩcm2 for the contact resistance of the membrane and catalyst layer ionomer. The improved mass transport is responsible for 90% of the increase in power density of the DMD fuel cell, while the reduced ionic resistance accounts for a 10% of the improvement.

  14. Algal production in wastewater treatment high rate algal ponds for potential biofuel use.

    PubMed

    Park, J B K; Craggs, R J

    2011-01-01

    Wastewater treatment High Rate Algal Ponds with CO2 addition could provide cost-effective and efficient tertiary-level wastewater treatment with the co-benefit of algal biomass production for biofuel use. Wastewater grown algal biomass can have a lipid content of 10-30% of dry weight, which could be used to make biodiesel. This research investigated algal biomass and total lipid production by two pilot-scale wastewater treatment HRAP(S) (4-day HRT) with and without CO2 addition under New Zealand mid summer (Nov-Jan) conditions. The influence of CO2 addition on wastewater treatment performance was also determined. CO2 was added to one of the HRAPs (the HRAP(E)) by maintaining the maximum pH of the pond below 8. Measurements of HRAP influent and effluent water qualities, total lipid content and algal biomass production were made twice a week over the experimental period. Both HRAP(S) achieved high levels of organic compound and nutrient removal, with >85% SBOD5, >92 NH4(+)-N and >70% DRP removal. Algal/bacterial biomass production in the HRAP(E) (15.2 g/m2/d) was improved by CO2 addition by approximately 30% compared with that of the control HRAP(W) (10.6 g/m2/d). Total lipid content of the biomass grown on both HRAP(S) was slightly reduced (from 25% to 20%) with CO2 addition and the maximum total lipid content of approximately 40% was observed in the HRAP(W) when low NH4(+)-N concentration (<0.5 mg/L) and high maximum pH (>10.0) occurred. Total lipid content of the biomass increased by approximately 15% under nitrogen limiting conditions, however, overall algal/bacterial biomass production was reduced by half during the period of nitrogen limitation. More research is required to maintain algal production under near nitrogen-limiting conditions.

  15. Algal endosymbionts in European Hydra strains reflect multiple origins of the zoochlorella symbiosis.

    PubMed

    Rajević, Nives; Kovačević, Goran; Kalafatić, Mirjana; Gould, Sven B; Martin, William F; Franjević, Damjan

    2015-12-01

    Symbiotic associations are of broad significance in evolution and biodiversity. Green Hydra is a classic example of endosymbiosis. In its gastrodermal myoepithelial cells it harbors endosymbiotic unicellular green algae, most commonly from the genus Chlorella. We reconstructed the phylogeny of cultured algal endosymbionts isolated and maintained in laboratory conditions for years from green Hydra strains collected from four different geographical sites within Croatia, one from Germany and one from Israel. Nuclear (18S rDNA, ITS region) and chloroplast markers (16S, rbcL) for maximum likelihood phylogenetic analyses were used. We focused on investigating the positions of these algal endosymbiotic strains within the chlorophyte lineage. Molecular analyses established that different genera and species of unicellular green algae are present as endosymbionts in green Hydra, showing that endosymbiotic algae growing within green Hydra sampled from four Croatian localities are not monophyletic. Our results indicate that the intracellular algal endosymbionts of green Hydra have become established several times independently in evolution.

  16. Simulation of photosynthetically active radiation distribution in algal photobioreactors using a multidimensional spectral radiation model.

    PubMed

    Kong, Bo; Vigil, R Dennis

    2014-04-01

    A numerical method for simulating the spectral light distribution in algal photobioreactors is developed by adapting the discrete ordinate method for solving the radiative transport equation. The technique, which was developed for two and three spatial dimensions, provides a detailed accounting for light absorption and scattering by algae in the culture medium. In particular, the optical properties of the algal cells and the radiative properties of the turbid culture medium were calculated using a method based on Mie theory and that makes use of information concerning algal pigmentation, shape, and size distribution. The model was validated using a small cylindrical bioreactor, and subsequently simulations were carried out for an annular photobioreactor configuration. It is shown that even in this relatively simple geometry, nontrivial photon flux distributions arise that cannot be predicted by one-dimensional models.

  17. Quantitative Autofluorescence and Cell Density Maps of the Human Retinal Pigment Epithelium

    PubMed Central

    Ach, Thomas; Huisingh, Carrie; McGwin, Gerald; Messinger, Jeffrey D.; Zhang, Tianjiao; Bentley, Mark J.; Gutierrez, Danielle B.; Ablonczy, Zsolt; Smith, R. Theodore; Sloan, Kenneth R.; Curcio, Christine A.

    2014-01-01

    Purpose. Lipofuscin (LF) accumulation within RPE cells is considered pathogenic in AMD. To test whether LF contributes to RPE cell loss in aging and to provide a cellular basis for fundus autofluorescence (AF) we created maps of human RPE cell number and histologic AF. Methods. Retinal pigment epithelium–Bruch's membrane flat mounts were prepared from 20 donor eyes (10 ≤ 51 and 10 > 80 years; postmortem: ≤4.2 hours; no retinal pathologies), preserving foveal position. Phalloidin-binding RPE cytoskeleton and LF-AF (488-nm excitation) were imaged at up to 90 predefined positions. Maps were assembled from 83,330 cells in 1470 locations. From Voronoi regions representing each cell, the number of neighbors, cell area, and total AF intensity normalized to an AF standard was determined. Results. Highly variable between individuals, RPE-AF increases significantly with age. A perifoveal ring of high AF mirrors rod photoreceptor topography and fundus-AF. Retinal pigment epithelium cell density peaks at the fovea, independent of age, yet no net RPE cell loss is detectable. The RPE monolayer undergoes considerable lifelong re-modeling. The relationship of cell size and AF, a surrogate for LF concentration, is orderly and linear in both groups. Autofluorescence topography differs distinctly from the topography of age-related rod loss. Conclusions. Digital maps of quantitative AF, cell density, and packing geometry provide metrics for cellular-resolution clinical imaging and model systems. The uncoupling of RPE LF content, cell number, and photoreceptor topography in aging challenges LF's role in AMD. PMID:25034602

  18. Quantum-dot density dependence of power conversion efficiency of intermediate-band solar cells

    NASA Astrophysics Data System (ADS)

    Sakamoto, Katsuyoshi; Kondo, Yasunori; Uchida, Keisuke; Yamaguchi, Koichi

    2012-12-01

    For intermediate-band solar cells containing GaAs/InAs quantum dots (QDs), the QD density dependence of the power conversion efficiency (PCE) was theoretically calculated for various sun concentrations under AM1.5 conditions based on detailed balance principles. A QD density of over 5 × 1013 cm-2 was required to achieve a PCE of more than 50% under 10 000 suns. However, under the photo-filled state and 1 sun, the PCE decreased over a wide total QD density range from about 3 × 1010 to 1 × 1013 cm-2. This reduction was attributed to the negative net carrier generation rate through the intermediate band, which was due to insufficient two-step optical absorption. The short-circuit current density increased as the QD density increased up to about 1 × 1011 cm-2 and it then saturated. In contrast, the open-circuit voltage decreased with increasing QD density. This reduction in the open-circuit voltage was suppressed at high sun concentrations.

  19. Dissolved organic matter reduces algal accumulation of methylmercury

    USGS Publications Warehouse

    Luengen, Allison C.; Fisher, Nicholas S.; Bergamaschi, Brian A.

    2012-01-01

    Dissolved organic matter (DOM) significantly decreased accumulation of methylmercury (MeHg) by the diatom Cyclotella meneghiniana in laboratory experiments. Live diatom cells accumulated two to four times more MeHg than dead cells, indicating that accumulation may be partially an energy-requiring process. Methylmercury enrichment in diatoms relative to ambient water was measured by a volume concentration factor (VCF). Without added DOM, the maximum VCF was 32 x 104, and the average VCF (from 10 to 72 h) over all experiments was 12.6 x 104. At very low (1.5 mg/L) added DOM, VCFs dropped by approximately half. At very high (20 mg/L) added DOM, VCFs dropped 10-fold. Presumably, MeHg was bound to a variety of reduced sulfur sites on the DOM, making it unavailable for uptake. Diatoms accumulated significantly more MeHg when exposed to transphilic DOM extracts than hydrophobic ones. However, algal lysate, a labile type of DOM created by resuspending a marine diatom in freshwater, behaved similarly to a refractory DOM isolate from San Francisco Bay. Addition of 67 μM L-cysteine resulted in the largest drop in VCFs, to 0.28 x 104. Although the DOM composition influenced the availability of MeHg to some extent, total DOM concentration was the most important factor in determining algal bioaccumulation of MeHg.

  20. Tumebacillus algifaecis sp. nov., isolated from decomposing algal scum.

    PubMed

    Wu, Yu-Fan; Zhang, Bo; Xing, Peng; Wu, Qing-Long; Liu, Shuang-Jiang

    2015-07-01

    Bacterial strain THMBR28(T) was isolated from decomposing algal scum that was collected during an algal bloom in Taihu lake, China. Cells of strain THMBR28(T) were Gram-staining-positive, facultatively anaerobic and rod-shaped. Growth was observed at 20-45 °C (optimum, 30 °C), at pH 5.0-9.5 (optimum, pH 6.5-7.5), and in the presence of 0-1.0% (w/v) NaCl (optimum, 0.5%). Strain THMBR28(T) contained MK-7 as the major menaquinone and iso-C15 : 0 as the major cellular fatty acid. The polar lipid profile contained phosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine and six unidentified polar lipids. The diamino acid found in the cell-wall peptidoglycan was meso-diaminopimelic acid. The DNA G+C content was 57.6 mol% (Tm). Phylogenetic analysis of 16S rRNA gene sequences showed that strain THMBR28(T) belonged to the genus Tumebacillus, most closely related to Tumebacillus ginsengisoli DSM 18389(T) (95.0%) and Tumebacillus permanentifrigoris Eur1 9.5(T) (93.4%). Based on phylogenetic and phenotypic characterization, it is concluded that strain THMBR28(T) represents a novel species of the genus Tumebacillus, for which the name Tumebacillus algifaecis sp. nov. is proposed, with THMBR28(T) ( = CGMCC 1.10949(T) = NBRC 108765(T)) as the type strain.

  1. Algal toxins alter copepod feeding behavior.

    PubMed

    Hong, Jiarong; Talapatra, Siddharth; Katz, Joseph; Tester, Patricia A; Waggett, Rebecca J; Place, Allen R

    2012-01-01

    Using digital holographic cinematography, we quantify and compare the feeding behavior of free-swimming copepods, Acartia tonsa, on nutritional prey (Storeatula major) to that occurring during exposure to toxic and non-toxic strains of Karenia brevis and Karlodinium veneficum. These two harmful algal species produce polyketide toxins with different modes of action and potency. We distinguish between two different beating modes of the copepod's feeding appendages-a "sampling beating" that has short durations (<100 ms) and involves little fluid entrainment and a longer duration "grazing beating" that persists up to 1200 ms and generates feeding currents. The durations of both beating modes have log-normal distributions. Without prey, A. tonsa only samples the environment at low frequency. Upon introduction of non-toxic food, it increases its sampling time moderately and the grazing period substantially. On mono algal diets for either of the toxic dinoflagellates, sampling time fraction is high but the grazing is very limited. A. tonsa demonstrates aversion to both toxic algal species. In mixtures of S. major and the neurotoxin producing K. brevis, sampling and grazing diminish rapidly, presumably due to neurological effects of consuming brevetoxins while trying to feed on S. major. In contrast, on mixtures of cytotoxin producing K. veneficum, both behavioral modes persist, indicating that intake of karlotoxins does not immediately inhibit the copepod's grazing behavior. These findings add critical insight into how these algal toxins may influence the copepod's feeding behavior, and suggest how some harmful algal species may alter top-down control exerted by grazers like copepods.

  2. Algal Toxins Alter Copepod Feeding Behavior

    PubMed Central

    Hong, Jiarong; Talapatra, Siddharth; Katz, Joseph; Tester, Patricia A.; Waggett, Rebecca J.; Place, Allen R.

    2012-01-01

    Using digital holographic cinematography, we quantify and compare the feeding behavior of free-swimming copepods, Acartia tonsa, on nutritional prey (Storeatula major) to that occurring during exposure to toxic and non-toxic strains of Karenia brevis and Karlodinium veneficum. These two harmful algal species produce polyketide toxins with different modes of action and potency. We distinguish between two different beating modes of the copepod’s feeding appendages–a “sampling beating” that has short durations (<100 ms) and involves little fluid entrainment and a longer duration “grazing beating” that persists up to 1200 ms and generates feeding currents. The durations of both beating modes have log-normal distributions. Without prey, A. tonsa only samples the environment at low frequency. Upon introduction of non-toxic food, it increases its sampling time moderately and the grazing period substantially. On mono algal diets for either of the toxic dinoflagellates, sampling time fraction is high but the grazing is very limited. A. tonsa demonstrates aversion to both toxic algal species. In mixtures of S. major and the neurotoxin producing K. brevis, sampling and grazing diminish rapidly, presumably due to neurological effects of consuming brevetoxins while trying to feed on S. major. In contrast, on mixtures of cytotoxin producing K. veneficum, both behavioral modes persist, indicating that intake of karlotoxins does not immediately inhibit the copepod’s grazing behavior. These findings add critical insight into how these algal toxins may influence the copepod’s feeding behavior, and suggest how some harmful algal species may alter top-down control exerted by grazers like copepods. PMID:22629336

  3. Comparison of nonciliated tracheal epithelial cells in six mammalian species: ultrastructure and population densities.

    PubMed

    Plopper, C G; Mariassy, A T; Wilson, D W; Alley, J L; Nishio, S J; Nettesheim, P

    1983-12-01

    Three types of nonciliated epithelial cells in mammalian conducting respiratory airways are thought to be secretory: mucous (goblet) cells, serous epithelial cells, and Clara cells. Mucous and serous cells are considered to be the secretory cells of the trachea. Clara cells are considered to be the secretory cells of the most distal conducting airways or bronchioles. To ascertain if mucous and serous epithelial cells are common to the tracheal epithelium of mammalian species, we characterized the ultrastructure and population densities of tracheal epithelial cells in six species: hamster (H), rat (Rt), rabbit (Rb), cat (C), Bonnet monkey (M. radiata) (B), and sheep (S). Following fixation by airway infusion with glutaraldehyde/paraformaldehyde, tracheal tissue was processed for light and electron microscopy (EM) by a selective embedding technique. Tracheal epithelium over cartilage was quantitated by light microscopy and characterized by transmission EM. Mucous cells were defined by abundant large nonhomogeneous granules, numerous Golgi complexes, basally located nuclei and granular endoplasmic reticulum (GER). The percentage of mucous cells in the tracheal epithelium was: H (0%), Rt (0.5%), Rb (1.3%), C (20.2%), B (8%), S (5.1%). Serous cells had homogeneous, electron-dense granules and extensive GER. Serous cells were present only in rats (39.2%). Clara cells had homogeneous electron-dense granules, abundant agranular endoplasmic reticulum (AER) and basal GER. Clara cells were found in hamsters (41.4%) and rabbits (17.6%). In sheep trachea, 35.9% of the epithelial cells had small electron-lucent granules, abundant AER and numerous Golgi complexes. In Bonnet monkey trachea, 16% of the epithelial cells had small electron-lucent granules, numerous polyribosomes, perinuclear Golgi apparatus and moderate GER. In cat trachea, 5.4% of the epithelial cells lacked granules, and had moderate numbers of mitochondria, moderate amounts of polyribosomes, a central nucleus, and

  4. A Photosynthesis Lab. Response of Algal Suspensions to a Gradient of Photosynthetically Active Radiation (PAR).

    ERIC Educational Resources Information Center

    Zee, Delmar Vander

    1995-01-01

    This photosynthesis exercise is intended for introductory college biology or botany courses. It is based on the principle that a closed suspension of algal cells may be expected to produce more dissolved oxygen with a greater photon fluence rate, but within limits of the photosynthetic capacity of the system. Describes materials and methods. (LZ)

  5. Low Density Lipoprotein Receptor Related Proteins as Regulators of Neural Stem and Progenitor Cell Function

    PubMed Central

    Landowski, Lila M.; Young, Kaylene M.

    2016-01-01

    The central nervous system (CNS) is a highly organised structure. Many signalling systems work in concert to ensure that neural stem cells are appropriately directed to generate progenitor cells, which in turn mature into functional cell types including projection neurons, interneurons, astrocytes, and oligodendrocytes. Herein we explore the role of the low density lipoprotein (LDL) receptor family, in particular family members LRP1 and LRP2, in regulating the behaviour of neural stem and progenitor cells during development and adulthood. The ability of LRP1 and LRP2 to bind a diverse and extensive range of ligands, regulate ligand endocytosis, recruit nonreceptor tyrosine kinases for direct signal transduction and signal in conjunction with other receptors, enables them to modulate many crucial neural cell functions. PMID:26949399

  6. New bioreactor for in situ simultaneous measurement of bioluminescence and cell density

    NASA Astrophysics Data System (ADS)

    Picart, Pascal; Bendriaa, Loubna; Daniel, Philippe; Horry, Habib; Durand, Marie-José; Jouvanneau, Laurent; Thouand, Gérald

    2004-03-01

    This article presents a new device devoted to the simultaneous measurement of bioluminescence and optical density of a bioluminescent bacterial culture. It features an optoelectronic bioreactor with a fully autoclavable module, in which the bioluminescent bacteria are cultivated, a modulated laser diode dedicated to optical density measurement, and a detection head for the acquisition of both bioluminescence and optical density signals. Light is detected through a bifurcated fiber bundle. This setup allows the simultaneous estimation of the bioluminescence and the cell density of the culture medium without any sampling. The bioluminescence is measured through a highly sensitive photomultiplier unit which has been photometrically calibrated to allow light flux measurements. This was achieved by considering the bioluminescence spectrum and the full optical transmission of the device. The instrument makes it possible to measure a very weak light flux of only a few pW. The optical density is determined through the laser diode and a photodiode using numerical synchronous detection which is based on the power spectrum density of the recorded signal. The detection was calibrated to measure optical density up to 2.5. The device was validated using the Vibrio fischeri bacterium which was cultivated under continuous culture conditions. A very good correlation between manual and automatic measurements processed with this instrument has been demonstrated. Furthermore, the optoelectronic bioreactor enables determination of the luminance of the bioluminescent bacteria which is estimated to be 6×10-5 W sr-1 m-2 for optical density=0.3. Experimental results are presented and discussed.

  7. High gravity and high cell density mitigate some of the fermentation inhibitory effects of softwood hydrolysates

    PubMed Central

    2013-01-01

    After steam pretreatment of lignocellulosic substrates the fermentation of the biomass derived sugars to ethanol is typically problematic because of both the generally low sugar concentrations that can be supplied and the presence of naturally occurring and process derived inhibitors. As the majority of the inhibitory materials are usually associated with the hemicellulose rich, water soluble component, this fraction was supplemented with glucose to simulate high solids, un-detoxified substrate to see if a high gravity/high cell consistency approach might better cope with inhibition. Several yeast strains were assessed, with the Tembec T1, T2 and Lallemand LYCC 6469 strains showing the greatest ethanol productivity and yield. The addition of supplemental glucose enabled the faster and quantitatively higher removal of hydroxymethylfurfural (HMF). High cell density could provide effective fermentation at high sugar concentrations while enhancing inhibitor reduction. A 77% ethanol yield could be achieved using strain LYCC 6469 after 48 h at high cell density. It was apparent that a high cell density approach improved ethanol production by all of the evaluated yeast strains. PMID:23410516

  8. Hippo signaling regulates Microprocessor and links cell density-dependent miRNA biogenesis to cancer

    PubMed Central

    Mori, Masaki; Triboulet, Robinson; Mohseni, Morvarid; Schlegelmilch, Karin; Shrestha, Kriti; Camargo, Fernando D.; Gregory, Richard I.

    2014-01-01

    SUMMARY Global downregulation of microRNAs (miRNAs) is commonly observed in human cancers and can have a causative role in tumorigenesis. The mechanisms responsible for this phenomenon remain poorly understood. Here we show that YAP, the downstream target of the tumor-suppressive Hippo signaling pathway regulates miRNA biogenesis in a cell density-dependent manner. At low cell density, nuclear YAP binds and sequesters p72 (DDX17), a regulatory component of the miRNA processing machinery. At high cell density, Hippo-mediated cytoplasmic retention of YAP facilitates p72 association with Microprocessor and binding to a specific sequence motif in pri-miRNAs. Inactivation of the Hippo pathway or expression of constitutively active YAP causes widespread miRNA suppression in cells and tumors and a corresponding post-transcriptional induction of MYC expression. Thus, the Hippo pathway links contact-inhibition regulation to miRNA biogenesis and may be responsible for the widespread miRNA repression observed in cancer. PMID:24581491

  9. Direct alcohol fuel cells: toward the power densities of hydrogen-fed proton exchange membrane fuel cells.

    PubMed

    Chen, Yanxin; Bellini, Marco; Bevilacqua, Manuela; Fornasiero, Paolo; Lavacchi, Alessandro; Miller, Hamish A; Wang, Lianqin; Vizza, Francesco

    2015-02-01

    A 2 μm thick layer of TiO2 nanotube arrays was prepared on the surface of the Ti fibers of a nonwoven web electrode. After it was doped with Pd nanoparticles (1.5 mgPd  cm(-2) ), this anode was employed in a direct alcohol fuel cell. Peak power densities of 210, 170, and 160 mW cm(-2) at 80 °C were produced if the cell was fed with 10 wt % aqueous solutions of ethanol, ethylene glycol, and glycerol, respectively, in 2 M aqueous KOH. The Pd loading of the anode was increased to 6 mg cm(-2) by combining four single electrodes to produce a maximum peak power density with ethanol at 80 °C of 335 mW cm(-2) . Such high power densities result from a combination of the open 3 D structure of the anode electrode and the high electrochemically active surface area of the Pd catalyst, which promote very fast kinetics for alcohol electro-oxidation. The peak power and current densities obtained with ethanol at 80 °C approach the output of H2 -fed proton exchange membrane fuel cells.

  10. Monoraphidium sp. as an algal feedstock for biodiesel: Determining optimal growth conditions in wastewater

    NASA Astrophysics Data System (ADS)

    Davidson, Zachary William

    This thesis set out to investigate different conditions for growth of the freshwater algal species Monoraphidium sp. for use as a feedstock for biodiesel. The algae was inoculated into effluent gathered from a local water treatment plant and placed into 50gal mesocosms. Cells were grown at large scale in wastewater, harvested, and run through extractions to collect lipids (26%DW). The lipids were then turned into biodiesel. The algae also removed most of the pollutants in the wastewater, lowering nitrate and phosphate levels usually to less than 1mg/L. Erlenmeyer flask cultures (1L) were used to determine optimal growth conditions for temperature (10°C), light intensity (30microE/m2/sec with a 10 hour photoperiod), and initial inoculation density (1x104cells/mL). The addition of bicarbonate during the initial or exponential growth phase had no effect on growth. It was concluded that Monoraphidium sp. grown in USDA Hardiness Zone 5 is capable of producing biodiesel.

  11. Nutrient enrichment, phytoplankton algal growth, and estimated rates of instream metabolic processes in the Quinebaug River Basin, Connecticut, 2000-2001

    USGS Publications Warehouse

    Colombo, Michael J.; Grady, Stephen J.; Todd Trench, Elaine C.

    2004-01-01

    A consistent and pervasive pattern of nutrient enrichment was substantiated by water-quality sampling in the Quinebaug River and its tributaries in eastern Connecticut during water years 2000 and 2001. Median total nitrogen and total phosphorus concentrations exceeded the U.S. Environmental Protection Agency?s recently recommended regional ambient water-qual-ity criteria for streams (0.71 and 0.031 milligrams per liter, respectively). Maximum total phosphorus concentrations exceeded 0.1 milligrams per liter at nearly half the sampled locations in the Quinebaug River Basin. Elevated total nitrogen and total phosphorus concentrations were measured at all stations on the mainstem of the Quinebaug River, the French River, and the Little River. Nutrient enrichment was related to municipal wastewater point sources at the sites on the mainstem of the Quinebaug River and French River, and to agricultural nonpoint nutrient sources in the Little River Basin. Nutrient enrichment and favorable physical factors have resulted in excessive, nuisance algal blooms during summer months, particularly in the numerous impoundments in the Quinebaug River system. Phytoplankton algal density as high as 85,000 cells per milliliter was measured during such nuisance blooms in water years 2000 and 2001. Different hydrologic conditions during the summers of 2000 and 2001 produced very different seston algal populations. Larger amounts of precipitation sustained higher streamflows in the summer of 2000 (than in 2001), which resulted in lower total algal abundance and inhibited the typical algal succession from diatoms to cyanobacteria. Despite this, nearly half of all seston chlorophyll-a concentrations measured during this study exceeded the recommended regional ambient stream-water-quality criterion (3.75 micrograms per liter), and seston chlorophyll-a concentrations as large as 42 micrograms per liter were observed in wastewa-ter-receiving reaches of the Quinebaug River. Estimates of primary

  12. Low density lipoprotein receptor-related protein 1 mediated endocytosis of β1-integrin influences cell adhesion and cell migration.

    PubMed

    Rabiej, Verena K; Pflanzner, Thorsten; Wagner, Timo; Goetze, Kristina; Storck, Steffen E; Eble, Johannes A; Weggen, Sascha; Mueller-Klieser, Wolfgang; Pietrzik, Claus U

    2016-01-01

    The low density lipoprotein receptor-related protein 1 (LRP1) has been shown to interact with β1-integrin and regulate its surface expression. LRP1 knock-out cells exhibit altered cytoskeleton organization and decreased cell migration. Here we demonstrate coupled endocytosis of LRP1 and β1-integrin and the involvement of the intracellular NPxY2 motif of LRP1 in this process. Mouse embryonic fibroblasts harboring a knock in replacement of the NPxY2 motif of LRP1 by a multiple alanine cassette (AAxA) showed elevated surface expression of β1-integrin and decreased β1-integrin internalization rates. As a consequence, cell spreading was altered and adhesion rates were increased in our cell model. Cells formed more focal adhesion complexes, whereby in vitro cell migration rates were decreased. Similar results could be observed in a corresponding mouse model, the C57Bl6 LRP1 NPxYxxL knock in mice, therefore, the biochemistry of cellular adhesion was altered in primary cortical neurons. In vivo cell migration experiments demonstrated a disturbance of neuroblast cell migration along the rostral migratory stream. In summary, our results indicate that LRP1 interacts with β1-integrin mediating integrin internalization and thus correlates with downstream signaling of β1-integrin such as focal adhesion dynamics. Consequently, the disturbance of this interaction resulted in a dysfunction in in vivo and in vitro cell adhesion and cell migration.

  13. Effects of two copper compounds on Microcystis aeruginosa cell density, membrane integrity, and microcystin release.

    PubMed

    Tsai, Kuo-Pei

    2015-10-01

    Microcystin release following Microcystis aeruginosa cell lysis after copper-based algaecide treatment is often cited as a concern leading to restricted use of algaecide in restoration of natural water resources. To examine this concern, bench-scale experiments were conducted to study responses of M. aeruginosa to 8-day copper exposures as copper sulfate and copper-ethanolamine (Cu-EA). M. aeruginosa UTEX 2385 was cultured in BG11 medium to cell density of 10(6)cells/mL with total and extracellular microcystin of 93 and 53μg/L, respectively. Exposures of copper concentration ranged from 40 to 1000μgCu/L. Cell membrane integrity was indicated by erythrosine B. In the end of experiment, total microcystin and cell density in untreated control (313μg/L and 10(7)cells/mL) was 3.3 and 10 times greater than pretreatment value, respectively. Minimum amount of copper required to reduce M. aeruginosa population within 8 days was 160μgCu/L as copper sulfate and 80μgCu/L as Cu-EA, where total and extracellular microcystin concentrations (47 and 44μg/L for copper sulfate; 56 and 44μg/L for Cu-EA) were degraded with degradation rate coefficient 0.1 day(-1) and were less than pretreatment values. Given a copper concentration at 80µgCu/L as Cu-EA, M. aeruginosa cells were intact and less microcystin were released compared to treatments at 160-1000µgCu/L, where lysed cells and relatively greater microcystin release were observed. Based on the laboratory results, a minimum amount of copper required for reducing M. aeruginosa population could decrease total microcystin concentration and not compromise cells and minimize microcystin release.

  14. Inhibition of osteoclast differentiation by polycyclic aryl hydrocarbons is dependent on cell density and RANKL concentration.

    PubMed

    Voronov, I; Heersche, J N M; Casper, R F; Tenenbaum, H C; Manolson, M F

    2005-07-15

    We investigated the effect of representative polycyclic aryl hydrocarbons (PAHs), benzo[a]pyrene (BaP), and 7,12-dimethylbenz[a]anthracene (DMBA) on osteoclast differentiation and function by using dispersed cancellous bone derived rabbit osteoclasts and the RAW264.7 cells. These cells differentiate into osteoclasts when exposed to receptor activator of NF-kappaB ligand (RANKL). The rabbit osteoclasts were exposed to 10(-6) to 10(-9)M BaP or DMBA and the tartrate-resistant acid phosphatase (TRAP)-positive cells were counted. The effect of PAHs on osteoclast differentiation in dispersed rabbit osteoclast-containing stromal cell populations was cell density dependent, suggesting that the cell density of stromal cells, osteoclast precursors, and/or mature osteoclasts are factors regulating the effect of PAHs. To investigate the direct effect of BaP on osteoclast differentiation, RAW264.7 cells were exposed to 10(-5) to 10(-6) M BaP. Treatment of RAW264.7 cells cultured with 25 ng/ml soluble RANKL and 10(-5)M BaP for 5 days decreased osteoclast differentiation, TRAP activity levels, and resorption of bone-like substrata. The inhibition was prevented by 10(-6) to 10(-7) M resveratrol, an aryl hydrocarbon receptor (AhR) antagonist, and by higher concentrations of RANKL. To investigate the ability of RANKL to reverse BaP-mediated inhibition, gene expression was determined by RT-PCR. Cytochrome P450 1B1 (CYP1B1) mRNA, one of the genes activated by BaP, was present only in the groups exposed to BaP; the levels of CYP1B1 mRNA decreased in the presence of increasing concentrations of RANKL. These results suggest that the inhibitory effects of PAHs on osteoclastogenesis are direct and likely involve interaction of the RANKL and PAH signaling pathways.

  15. Number Density of Mast Cells in the Primo Nodes of Rats.

    PubMed

    Gil, HyunJi; Bae, Kyoung-Hee; Kim, LiJung; Kim, SungChul; Soh, Kwang-Sup

    2015-12-01

    Mast cells (MCs) play a major role in allergic reactions. Surprisingly, the acupuncture points have a higher density of MCs compared with nonacupoints in the skin, which is consistent with the augmentation of the immune function by acupuncture treatment. We hypothesized that the primo vascular system (PVS), which was proposed as the anatomical structure of the acupuncture points and meridians, should have a high density of MCs. In order to test that hypothesis, we investigated the primo nodes isolated from the surfaces of internal organs, such as the liver, the small and the large intestines, and the bladder. The harvested primo nodes were stained with toluidine blue, and the MCs were easily recognized by their red-purple stains and their characteristic granules. The results showed a high density of MCs in the primo nodes and confirmed the hypothesis. The MCs were uniformly distributed in the nodes. The relative concentration of the MCs with respect to other cells was ∼15%. We divided the sizes of the primo nodes into three classes: large, medium, and small. The number density and the relative concentration of MCs did not show a size-dependence. The current work suggests that the PVS may participate in the immune response to allergic inflammation, which closely involves MCs.

  16. Regeneration and control of human fibroblast cell density by intermittently delivered pulsed electric fields.

    PubMed

    Golberg, Alexander; Bei, Marianna; Sheridan, Robert L; Yarmush, Martin L

    2013-06-01

    Proliferative scarring is a human disease with neither available effective treatment nor relevant animal model. One of the hypotheses for scar formation involves deregulation of fibroblast signaling and delayed apoptosis. Here, we introduce a new chemical-free method for fibroblast density control in culture by intermittently delivered pulsed electric fields (IDPEF), which cause irreversible damage to cell membranes. Using 5-100 pulses with electric field strength of 150 V/mm, pulse duration 70 µs, and frequency of 1 Hz, we investigated the effects of PEF application on growth, death, and regeneration of normal human dermal fibroblasts in culture. We found that the fraction of fibroblasts that survive depends on the number of pulses applied and follows a Weibull distribution. We have successfully developed an IDPEF protocol that controls fibroblasts density in culture. Specifically, through application of IDPEF every 72 h for 12 days, we maintain a normal human dermal fibroblast density in the 3.1 ± 0.2 × 10(5) -1.4 ± 0.2 × 10(5)  cell/mL range. Our results suggest that IDPEFs may prove useful as a non-chemical method for fibroblast density control in human wound healing.

  17. A Novel High-Cell-Density Protein Expression System Based on Ralstonia eutropha

    PubMed Central

    Srinivasan, Sriram; Barnard, Gavin C.; Gerngross, Tillman U.

    2002-01-01

    We describe the development of a novel protein expression system based on the industrial fermentation organism Ralstonia eutropha (formerly known as Alcaligenes eutrophus) NCIMB 40124. This new system overcomes some of the shortcomings of traditional Escherichia coli-based protein expression systems, particularly the propensity of such systems to form inclusion bodies during high-level expression. Using a proteomics approach, we identified promoters that can be induced by simple process parameters or medium compositions in high-density cell culture or shake flasks, respectively. By combining newly developed molecular biological tools with a high-cell-density fermentation process, we were able to produce high levels (>1 g/liter) of soluble, active organophosphohydrolase, a model enzyme prone to inclusion body formation in E. coli. PMID:12450812

  18. High CD4+ T cell density is associated with poor prognosis in patients with non-muscle-invasive bladder cancer

    PubMed Central

    Zhang, Qinglei; Hao, Chongli; Cheng, Guangzhou; Wang, Lei; Wang, Xiang; Li, Chang; Qiu, Juhui; Ding, Kejia

    2015-01-01

    Purpose: The aim of this study was to investigate the clinical significance of CD4+ T cells in non-muscle-invasive bladder cancer (NMIBC) tissues in situ. Methods: Immunohistochemistry was used to examine the distribution of CD4+ T cells in 131 NMIBC tissues. Kaplan-Meier analysis and Cox proportional hazards regression models were applied to estimate overall survival (OS) and recurrence-free survival (RFS). Results: NMIBC patients were divided into two groups based on the median frequency of CD4+ T cells (median, 1/×400 high resolution). On univariate analysis, CD4+ T cell density was inversely associated with overall survival (P = 0.01). In those patients with high CD4+ T density, 5-year OS rates was only 77%, compared with 86% in those with low density, respectively. Although CD4+ T cell density showed no prognostic significance for RFS (P = 0.36), 5-year RFS rates of patients with high CD4+ T density (58%) was lower than those of patients with low CD4+ T density (65%, respectively). By multivariate analysis, tumor infiltrating CD4+ T cell density emerged as an independent prognostic factor for OS (HR, 2.75; P = 0.004). In addition, no association was found between CD4+ T cell density and any clinicopathological variables (P > 0.05). Conclusion: Our findings suggest that CD4+ T cells could potentially serve as a poor prognostic marker for patients with NMIBC. PMID:26617883

  19. Systems biology. Conditional density-based analysis of T cell signaling in single-cell data.

    PubMed

    Krishnaswamy, Smita; Spitzer, Matthew H; Mingueneau, Michael; Bendall, Sean C; Litvin, Oren; Stone, Erica; Pe'er, Dana; Nolan, Garry P

    2014-11-28

    Cellular circuits sense the environment, process signals, and compute decisions using networks of interacting proteins. To model such a system, the abundance of each activated protein species can be described as a stochastic function of the abundance of other proteins. High-dimensional single-cell technologies, such as mass cytometry, offer an opportunity to characterize signaling circuit-wide. However, the challenge of developing and applying computational approaches to interpret such complex data remains. Here, we developed computational methods, based on established statistical concepts, to characterize signaling network relationships by quantifying the strengths of network edges and deriving signaling response functions. In comparing signaling between naïve and antigen-exposed CD4(+) T lymphocytes, we find that although these two cell subtypes had similarly wired networks, naïve cells transmitted more information along a key signaling cascade than did antigen-exposed cells. We validated our characterization on mice lacking the extracellular-regulated mitogen-activated protein kinase (MAPK) ERK2, which showed stronger influence of pERK on pS6 (phosphorylated-ribosomal protein S6), in naïve cells as compared with antigen-exposed cells, as predicted. We demonstrate that by using cell-to-cell variation inherent in single-cell data, we can derive response functions underlying molecular circuits and drive the understanding of how cells process signals.

  20. Cell density-regulated recovery of starved biofilm populations of ammonia-oxidizing bacteria.

    PubMed Central

    Batchelor, S E; Cooper, M; Chhabra, S R; Glover, L A; Stewart, G S; Williams, P; Prosser, J I

    1997-01-01

    The speed of recovery of cell suspensions and biofilm populations of the ammonia oxidizer Nitrosomonas europaea, following starvation was determined. Stationary-phase cells, washed and resuspended in ammoniumfree inorganic medium, were starved for periods of up to 42 days, after which the medium was supplemented with ammonium and subsequent growth was monitored by measuring nitrite concentration changes. Cultures exhibited a lag phase prior to exponential nitrite production, which increased from 8.72 h (no starvation) to 153 h after starvation for 42 days. Biofilm populations of N. europaea colonizing sand or soil particles in continuous-flow, fixed column reactors were starved by continuous supply of ammonium-free medium. Following resupply of ammonium, starved biofilms exhibited no lag phase prior to nitrite production, even after starvation for 43.2 days, although there was evidence of cell loss during starvation. Biofilm formation will therefore provide a significant ecological advantage for ammonia oxidizers in natural environments in which the substrate supply is intermittent. Cell density-dependent phenomena in a number of gram-negative bacteria are mediated by N-acyl homoserine lactones (AHL), including N-(3-oxohexanoyl)-L-homoserine lactone (OHHL). Addition of both ammonium and OHHL to cell suspensions starved for 28 days decreased the lag phase in a concentration-dependent manner from 53.4 h to a minimum of 10.8 h. AHL production by N. europaea was detected by using a luxR-luxAB AHL reporter system. The results suggest that rapid recovery of high-density biofilm populations may be due to production and accumulation of OHHL to levels not possible in relatively low-density cell suspensions. PMID:9172348

  1. Energy-efficient photobioreactor configuration for algal biomass production.

    PubMed

    Pegallapati, Ambica Koushik; Arudchelvam, Yalini; Nirmalakhandan, Nagamany

    2012-12-01

    An internally illuminated photobioreactor (IIPBR) design is proposed for energy-efficient biomass production. Theoretical rationale of the IIPBR design and its advantages over the traditional bubble column photobioreactors (PBRs) are presented, followed by experimental results from prototype scale cultivation of freshwater and marine algal strains in an 18L IIPBR. Based on theoretical considerations, the proposed IIPBR design has the potential to support 160% higher biomass density and higher biomass productivity per unit energy input, B/E, than a bubble column PBR of equal incident area per unit culture volume. Experimental B/E values recorded in this study with fresh water algae and marine algae (1.42 and 0.37 gW(-1)d(-1), respectively) are at least twice as those reported in the literature for comparable species cultivated in bubble column and airlift PBRs.

  2. The Proportion of ALDEFLUOR-Positive Cancer Stem Cells Changes with Cell Culture Density Due to the Expression of Different ALDH Isoforms

    PubMed Central

    Opdenaker, Lynn M.; Modarai, Shirin R.; Boman, Bruce M.

    2017-01-01

    A significant number of discrepancies exist within the literature regarding ALDEFLUOR-positive stem cell populations in cell lines. We hypothesized that these inconsistencies resulted from differences in culture conditions, particularly cell density. We cultured several colon cancer cell lines (N=8) at high and low densities and found a significant decrease in ALDEFLUOR-positive cell populations at high density. However, we found no changes in the CD166-positive stem cell population, self-renewal, or cell cycle distribution of cells cultured at different densities. Interestingly, when we sorted both ALDEFLUOR positive and negative populations from the different density cultures, we identified a significant number of Aldehyde dehydrogenase (ALDH) isoforms whose expression was decreased in ALDEFLUOR-positive stem cells cultured at high density. This novel finding suggests that multiple ALDH isoforms contribute to ALDEFLUOR activity in colon cancer stem cells and decreases in ALDEFLUOR-positive stem cells at high cell density are due to decreased expression of multiple ALDH isoforms. Thus, designing therapeutics to target ALDEFLUOR-positive cancer stem cells may require inhibition of multiple ALDH isoforms.

  3. New stopping cell capabilities: RF carpet performance at high gas density and cryogenic operation

    NASA Astrophysics Data System (ADS)

    Ranjan, M.; Purushothaman, S.; Dickel, T.; Geissel, H.; Plass, W. R.; Schäfer, D.; Scheidenberger, C.; Van de Walle, J.; Weick, H.; Dendooven, P.

    2011-12-01

    We have developed a stopping cell to be used at the FRS and Super-FRS (Super-conducting FRagment Separator) at the GSI Helmholtz Centre for Heavy-Ion Research and the Facility for Antiproton and Ion Research (FAIR), both in Darmstadt, Germany. The cell has a stopping volume with a length of 1 m and a diameter of 25 cm. It is aimed at operation with high-density helium gas (up to 0.2 mg/cm3). Ours is the first realisation of a stopping cell in which the required purity of the helium stopping gas is ensured by operation at cryogenic temperatures. On the exit side, the ions are guided to the exit hole by an RF carpet with 4 electrodes per mm, operating at a frequency of 5.8 MHz. We present the first commissioning results of the cryogenic stopping cell. Using 219Rn ions emitted as alpha-decay recoils from a 223Ra source, a combined ion survival and extraction efficiency between 10 and 25% is measured for helium gas at a temperature of 85 K and with a density up to 0.07 mg/cm3 (equivalent to a pressure of 430 mbar at room temperature). This density is almost two times higher than demonstrated up to now for RF ion repelling structures in helium gas. Given the operational and design parameters of the system, it is projected that this technology is useful up to a helium gas density of at least 0.2 mg/cm3.

  4. Evidence for osmoregulation of cell growth and buoyant density in Escherichia coli

    SciTech Connect

    Baldwin, W.W.; Kubitschek, H.E.

    1984-07-01

    The buoyant density of cells of Escherichia coli B/r NC32 increased with the osmolarity of the growth medium. Growth rate and its variability were also dependent upon the osmolarity of the medium. Maximum growth rates and minimum variability of these rates were obtained in Luria broth by addition of NaCl to a concentration of about 0.23 M. 6 references, 1 figure, 1 table.

  5. Retinal ganglion cell density of the black rhinoceros (Diceros bicornis): calculating visual resolution.

    PubMed

    Pettigrew, John D; Manger, Paul R

    2008-01-01

    A single right retina from a black rhinoceros was whole mounted, stained and analyzed to determine the visual resolution of the rhinoceros, an animal with reputedly poor eyesight. A range of small (15-microm diameter) to large (100-microm diameter) ganglion cell types was seen across the retina. We observed two regions of high density of retinal ganglion cells at either end of a long, but thin, horizontal streak. The temporal specialization, which receives light from the anterior visual field, exhibited a ganglion cell density of approximately 2000/mm2, while the nasal specialization exhibited a density of approximately 1500/mm2. The retina exhibited a ganglion cell density bias toward the upper half, especially so, the upper temporal quadrant, indicating that the rhinoceros would be processing visual information from the visual field below the anterior horizon for the most part. Our calculations indicate that the rhinoceros has a visual resolution of 6 cycles/degree. While this resolution is one-tenth that of humans (60 cycles/deg) and less than that of the domestic cat (9 cycles/deg), it is comparable to that of the rabbit (6 cycles/deg), and exceeds that seen in a variety of other mammals including seals, dolphins, microbats, and rats. Thus, the reputation of the rhinoceros as a myopic, weakly visual animal is not supported by our observations of the retina. We calculate that the black rhinoceros could readily distinguish a 30 cm wide human at a distance of around 200 m given the appropriate visual background.

  6. Investigating cell culture dynamics combining high density recordings with dimensional reduction techniques.

    PubMed

    Nieus, Thierry; Di Marco, Stefano; Maccione, Alessandro; Amin, Hayder; Berdondini, Luca

    2015-08-01

    High density multielectrode array recordings with CMOS-MEAs allow to monitor cell culture activity with unprecedent details respect to previous recording techniques. This is clarifying how network activity develops and is motivating the development of novel data analysis tools. Here, in order to advance in the exploitation of the richness of these large-scale array recordings, we introduce a principal component analysis approach that aims at improving on existing methodologies to describe neural activity events within large networks.

  7. Autonomous Bacterial Localization and Gene Expression Based on Nearby Cell Receptor Density

    DTIC Science & Technology

    2013-01-22

    density, these cells expressed marker proteins to indicate phenotypic response. Specifically, site-specific synthesis of bacterial quorum sensing ...Escherichia coli; quorum sensing ; synthetic biology Introduction Synthetic biology engenders design-based rewiring of a cell’s genetic circuitry for the...the signal transduction processes of quorum sensing (QS) as a means of inter- and intra-species communication and the coordination of population-based

  8. Advanced Microbial Fuel Cell Development, Miniaturization and Energy and Power Density Enhancement

    DTIC Science & Technology

    2007-04-30

    fuel cell development, miniaturization, and energy and power density enhancement. The anode is very important in the performance of a microbial fuel cell "MFC", and is often the limiting factor for a high power output. In present work, we used the CNT/PANI composite as the anode materials of MFCs for the first time and investigated the electrocatalytic properties of the composite associated with the bacterium biocatalyst. A method was developed to fabricate a nanostructured CNT/PANI composite anode for

  9. The Impact of Cell Density and Mutations in a Model of Multidrug Resistance in Solid Tumors

    PubMed Central

    Greene, James; Lavi, Orit; Gottesman, Michael M.; Levy, Doron

    2016-01-01

    In this paper we develop a mathematical framework for describing multidrug resistance in cancer. To reflect the complexity of the underlying interplay between cancer cells and the therapeutic agent, we assume that the resistance level is a continuous parameter. Our model is written as a system of integro-differential equations that are parametrized by the resistance level. This model incorporates the cell-density and mutation dependence. Analysis and simulations of the model demonstrate how the dynamics evolves to a selection of one or more traits corresponding to different levels of resistance. The emerging limit distribution with nonzero variance is the desirable modeling outcome as it represents tumor heterogeneity. PMID:24553772

  10. The effect of cell density on the production of xylitol from D-xylose by yeast.

    PubMed

    Cao, N J; Tang, R; Gong, C S; Chen, L F

    1994-01-01

    The rate of xylitol production from D-xylose increased with increasing yeast cell density. The optimal temperature for xylitol production is 36 degrees C, and the optimal pH range is from 4.0 to 6.0. At high initial yeast cell concentration of 26 mg/mL, 210 g/L of xylitol was produced from 260 g/L of D-xylose after 96 h of incubation with an indicated yield of 81% of the theoretical value.

  11. Quantification of nanoscale density fluctuations using electron microscopy: Light-localization properties of biological cells

    SciTech Connect

    Pradhan, Prabhakar; Damania, Dhwanil; Turzhitsky, Vladimir; Subramanian, Hariharan; Backman, Vadim; Joshi, Hrushikesh M.; Dravid, Vinayak P.; Roy, Hemant K.; Taflove, Allen

    2010-12-13

    We report a study of the nanoscale mass-density fluctuations of heterogeneous optical dielectric media, including nanomaterials and biological cells, by quantifying their nanoscale light-localization properties. Transmission electron microscope images of the media are used to construct corresponding effective disordered optical lattices. Light-localization properties are studied by the statistical analysis of the inverse participation ratio (IPR) of the localized eigenfunctions of these optical lattices at the nanoscale. We validated IPR analysis using nanomaterials as models of disordered systems fabricated from dielectric nanoparticles. As an example, we then applied such analysis to distinguish between cells with different degrees of aggressive malignancy.

  12. Lectin-like oxidized low-density lipoprotein receptor (LOX-1) in sickle cell disease vasculopathy.

    PubMed

    Chen, Mingyi; Qiu, Hong; Lin, Xin; Nam, David; Ogbu-Nwobodo, Lucy; Archibald, Hannah; Joslin, Amelia; Wun, Ted; Sawamura, Tatsuya; Green, Ralph

    2016-09-01

    Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL. Increased expression of LOX-1 has been demonstrated in atherosclerotic lesions and diabetic vasculopathy. In this study, we investigate the expression of LOX-1 receptor in sickle cell disease (SCD) vasculopathy. Expression of LOX-1 in brain vascular endothelium is markedly increased and LOX-1 gene expression is upregulated in cultured human brain microvascular endothelial cells by incubation with SCD erythrocytes. Also, the level of circulating soluble LOX-1 concentration is elevated in the plasma of SCD patients. Increased LOX-1 expression in endothelial cells is potentially involved in the pathogenesis of SCD vasculopathy. Soluble LOX-1 concentration in SCD may provide a novel biomarker for risk stratification of sickle cell vascular complications.

  13. Lectin-like oxidized low-density lipoprotein receptor (LOX-1) in sickle cell disease vasculopathy

    PubMed Central

    Chen, Mingyi; Qiu, Hong; Lin, Xin; Nam, David; Ogbu-Nwobodo, Lucy; Archibald, Hannah; Joslin, Amelia; Wun, Ted; Sawamura, Tatsuya; Green, Ralph

    2017-01-01

    Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL. Increased expression of LOX-1 has been demonstrated in atherosclerotic lesions and diabetic vasculopathy. In this study, we investigate the expression of LOX-1 receptor in sickle cell disease (SCD) vasculopathy. Expression of LOX-1 in brain vascular endothelium is markedly increased and LOX-1 gene expression is upregulated in cultured human brain microvascular endothelial cells by incubation with SCD erythrocytes. Also, the level of circulating soluble LOX-1 concentration is elevated in the plasma of SCD patients. Increased LOX-1 expression in endothelial cells is potentially involved in the pathogenesis of SCD vasculopathy. Soluble LOX-1 concentration in SCD may provide a novel biomarker for risk stratification of sickle cell vascular complications. PMID:27519944

  14. Production of nattokinase by high cell density fed-batch culture of Bacillus subtilis.

    PubMed

    Kwon, Eun-Yeong; Kim, Kyung Mi; Kim, Mi Kyoung; Lee, In Young; Kim, Beom Soo

    2011-09-01

    Bacillus subtilis was cultivated to high cell density for nattokinase production by pH-stat fed-batch culture. A concentrated mixture solution of glucose and peptone was automatically added by acid-supplying pump when culture pH rose above high limit. Effect of the ratio of glucose to peptone in feeding solution was investigated on cell growth and nattokinase production by changing the ratio from 0.2 to 5 g glucose/g peptone. The highest cell concentration was 77 g/L when the ratio was 0.2 g glucose/g peptone. Cell concentration decreased with increasing the ratio of glucose to peptone in feeding solution, while the optimum condition existed for nattokinase production. The highest nattokinase activity was 14,500 unit/mL at a ratio of 0.33 g glucose/g peptone, which was 4.3 times higher than that in batch culture.

  15. Cheese whey-induced high-cell-density production of recombinant proteins in Escherichia coli.

    PubMed

    Viitanen, Mikko I; Vasala, Antti; Neubauer, Peter; Alatossava, Tapani

    2003-04-09

    BACKGROUND: Use of lactose-rich concentrates from dairy processes for the induction of recombinant gene's expression has not received much attention although they are interesting low cost substrates for production of recombinant enzymes. Applicability of dairy waste for induction of recombinant genes in Escherichia coli was studied. Clones expressing Lactobacillus phage muramidase and Lactobacillus alcohol dehydrogenase were used for the experiments. RESULTS: Shake flask cultivations in mineral salt medium showed that cheese whey or deproteinised whey induced gene expression as efficiently as IPTG (isopropyl-beta-D-thiogalactopyranoside) or pure lactose. Addition of yeast extract or proteolytically degraded whey proteins did not improve the recombinant protein yield. In contrast, addition of yeast extract to the well-balanced mineral salt medium decreased the product yield. Feeding with glycerol provided sufficient amount of easily assimilable carbon source during the induction period without preventing lactose intake and induction by lactose. High-cell-density fed-batch cultivations showed that product yields comparable to IPTG-induction can be achieved by feeding bacteria with a mixture of glycerol and concentrated whey permeate during the induction. CONCLUSION: Whey and concentrated whey permeate can be applied as an alternative inducer in recombinant high-cell-density fed-batch fermentations. The yield of the recombinant product was comparable to fermentations induced by IPTG. In low-cell-density shake flask experiments the yield was higher with whey or whey permeate than with IPTG.

  16. Ferritin protects endothelial cells from oxidized low density lipoprotein in vitro.

    PubMed Central

    Juckett, M. B.; Balla, J.; Balla, G.; Jessurun, J.; Jacob, H. S.; Vercellotti, G. M.

    1995-01-01

    Low density lipoprotein (LDL), if it becomes oxidized, develops several unique properties including the capacity to provoke endothelial cytotoxicity via metal-catalyzed free radical-mediated mechanisms. As were previously have shown that iron-catalyzed oxidant injury to endothelial cells can be attenuated by the addition of exogenous iron chelators such as the lazaroids and deferoxamine, we have examined whether the endogenous iron chelator, ferritin, might provide protection from oxidized LDL. LDL oxidized by iron-containing hemin and H2O2 is toxic to endothelial cells in a time- and dose-dependent fashion. Endothelial cell ferritin content is increased by pretreatment of cells with iron compounds or by the direct addition of exogenous apoferritin; ferritin-loaded cells are markedly resistant to the toxicity caused by oxidized LDL. Iron inactivation by ferritin depends on its ferroxidase activity. When a recombinant human ferritin heavy chain mutant, 222, which is devoid of ferroxidase activity, is added to endothelial cells, unlike the excellent protection afforded by the wild-type recombinant heavy chain, endothelial cells are not protected from oxidized LDL. To assess the in vivo relevance of our observation, we examined human coronary arteries of cardiac explants taken from patients with end-stage atherosclerosis. Large amounts of immunoreactive ferritin are focally detected in atherosclerotic lesions, specifically in the myofibroblasts, macrophages, and endothelium without a notable increase in Prussian blue-detectable iron. These findings suggest that ferritin may modulate vascular cell injury in vivo. Images Figure 3 Figure 4 PMID:7677189

  17. Generation of murine induced pluripotent stem cells by using high-density distributed electrodes network.

    PubMed

    Lu, Ming-Yu; Li, Zhihong; Hwang, Shiaw-Min; Linju Yen, B; Lee, Gwo-Bin

    2015-09-01

    This study reports a robust method of gene transfection in a murine primary cell model by using a high-density electrodes network (HDEN). By demonstrating high cell viability after gene transfection and successful expression of transgenes including fluorescent proteins, the HDEN device shows great promise as a solution in which reprogramming efficiency using non-viral induction for generation of murine induced pluripotent stem cells (iPSCs) is optimized. High and steady transgene expression levels in host cells of iPSCs can be demonstrated using this method. Moreover, the HDEN device achieved successful gene transfection with a low voltage of less than 180 V while requiring relatively low cell numbers (less than 1.5 × 10(4) cells). The results are comparable to current conventional methods, demonstrating a reasonable fluorescent-plasmid transfection rate (42.4% in single transfection and 24.5% in triple transfection) and high cell viability of over 95%. The gene expression levels of each iPSC factor was measured to be over 10-fold higher than that reported in previous studies using a single mouse embryonic fibroblast cell. Our results demonstrate that the generation of iPSCs using HDEN transfection of plasmid DNA may be a feasible and safe alternative to using viral transfection methods in the near future.

  18. Protein modification elicited by oxidized low-density lipoprotein (LDL) in endothelial cells: protection by (-)-epicatechin.

    PubMed

    Steffen, Yvonne; Jung, Tobias; Klotz, Lars-Oliver; Schewe, Tankred; Grune, Tilman; Sies, Helmut

    2007-04-01

    The action of oxidatively modified low-density lipoprotein (oxLDL) on vascular endothelial cells has been proposed to be a crucial process leading to endothelial dysfunction and atherogenesis. OxLDL was shown here to elicit oxidative stress in bovine aortic endothelial cells or human umbilical vein endothelial cells, as judged by an increase in 2',7'-dichlorofluorescein fluorescence and elevated levels of carbonylated, nitrated, and 2-hydroxynonenal-coupled proteins. These effects were sensitive to apocynin, indicating involvement of NADPH oxidase. A 170-kDa polypeptide carbonylated upon exposure of cells to oxLDL was identified by immunoprecipitation as EGF receptor. Immunocytochemical visualization by confocal microscopy revealed the highest levels of modified proteins in the perinuclear region. Exposure of endothelial cells to oxLDL led to modulation of the expression levels of *NO synthases; the endothelial isoform (eNOS) was down-regulated via proteasomal degradation, whereas the inducible isoform (iNOS) was up-regulated in an enzymatically active state. eNOS protein was found to be both carbonylated and nitrated upon exposure of cells to oxLDL. iNOS contributed to the generation of modified proteins as judged by the effects of the selective inhibitor L-NIO. These oxLDL-elicited changes in vascular endothelial cells described were suppressed by (-)-epicatechin, a dietary polyphenol, which inhibited NADPH oxidase activity in these cells.

  19. Screening of surfactants for harmful algal blooms mitigation.

    PubMed

    Sun, Xiao-Xia; Han, Kyung-Nam; Choi, Joong-Ki; Kim, Eun-Ki

    2004-05-01

    Screening experiments were conducted in order to find promising synthetic surfactants for harmful algal blooms (HABs) mitigation. The chemically synthesized surfactant cocamidopropyl betaine (CAPB) showed characteristics of relatively high inhibition efficiency, high biodegradability and low cost. The motility inhibition ratios of 10 mg/L CAPB on Cochlodinium polykrikoides and Alexandrium tamarense were about 60% after 5 min. The biodegradation test indicated that the half-life of CAPB in seawater was shorter than one day and 90% was biodegraded after five days under the initial concentration of 100 mg/L at 25 degrees C. Further cell lysis experiments revealed the selective lysis effect of CAPB on different HAB organisms. More than 90% of C. polykrikoides lysed at the concentration of 10 mg/L CAPB after 24 h and at 15 mg/L CAPB after 4 h, whereas the lysis effect of CAPB on A. tamarense was slight, no more than 10% after 2 h interaction with 50 mg/L CAPB. This research provided preliminary data for CAPB as a candidate in harmful algal blooms mitigation and pointed out unresolved problems for its practical application in the meantime.

  20. Didymosphenia geminata: Algal blooms in oligotrophic streams and rivers

    USGS Publications Warehouse

    Sundareshwar, P.V.; Upadhayay, S.; Abessa, M.; Honomichl, S.; Berdanier, B.; Spaulding, S.A.; Sandvik, C.; Trennepohl, A.

    2011-01-01

    In recent decades, the diatom Didymosphenia geminata has emerged as nuisance species in river systems around the world. This periphytic alga forms large "blooms" in temperate streams, presenting a counterintuitive result: the blooms occur primarily in oligotrophic streams and rivers, where phosphorus (P) availability typically limits primary production. The goal of this study is to examine how high algal biomass is formed under low P conditions. We reveal a biogeochemical process by which D. geminata mats concentrate P from flowing waters. First, the mucopolysaccaride stalks of D. geminata adsorb both iron (Fe) and P. Second, enzymatic and bacterial processes interact with Fe to increase the biological availability of P. We propose that a positive feedback between total stalk biomass and high growth rate is created, which results in abundant P for cell division. The affinity of stalks for Fe in association with iron-phosphorus biogeochemistry suggest a resolution to the paradox of algal blooms in oliogotrophic streams and rivers. Copyright 2011 by the American Geophysical Union.

  1. Combined effect of concentrations of algal food (Chlorella vulgaris) and salt (sodium chloride) on the population growth of Brachionus calyciflorus and Brachionus patulus (Rotifera).

    PubMed

    Peredo-Alvarez, Víctor M; Sarma, S S; Nandini, S

    2003-06-01

    Salinity is an important variable influencing the density and diversity of rotifers. Studies on salt tolerance of rotifers have so far concentrated on euryhaline species while very little information is available on non-euryhaline taxa. In the present work, we have evaluated the combined effects of Chlorella vulgaris and sodium chloride on the population growth of two freshwater rotifers B. calyciflorus and B. patulus. A 24 hr acute tolerance test using NaCl revealed that B. calyciflorus was more resistant (LC50 = 3.75 +/- 0.04 g l-1) than B. patulus (2.14 +/- 0.09 g l-1). The maximal population density (mean +/- standard error) for B. calyciflorus in the control at 4.5 x 10(6) cells ml-1 (algal level) was 80 +/- 5 ind. ml-1, which was nearly a fifth of the one for B. patulus (397 +/- 7 ind. ml-1) under comparable conditions. Data on population growth revealed that regardless of salt concentration, the density of B. calyciflorus increased with increasing food levels, while for B. patulus, this trend was evident only in the controls. Regardless of salt concentration and algal food level, the day of maximal population density was lower (4 +/- 0.5 days) for B. calyciflorus than for B. patulus (11 +/- 1 day). The highest rates of population increase (r values) for B. calyciflorus and B. patulus were 0.429 +/- 0.012 and 0.367 +/- 0.004, respectively, recorded at 4.5 x 10(6) cells ml-1 of Chlorella in the controls. The protective role of algae in reducing the effect of salt stress was more evident in B. calyciflorus than B. patulus.

  2. Characterisation of algal organic matter produced by bloom-forming marine and freshwater algae.

    PubMed

    Villacorte, L O; Ekowati, Y; Neu, T R; Kleijn, J M; Winters, H; Amy, G; Schippers, J C; Kennedy, M D

    2015-04-15

    Algal blooms can seriously affect the operation of water treatment processes including low pressure (micro- and ultra-filtration) and high pressure (nanofiltration and reverse osmosis) membranes mainly due to accumulation of algal-derived organic matter (AOM). In this study, the different components of AOM extracted from three common species of bloom-forming algae (Alexandrium tamarense, Chaetoceros affinis and Microcystis sp.) were characterised employing various analytical techniques, such as liquid chromatography - organic carbon detection, fluorescence spectroscopy, fourier transform infrared spectroscopy, alcian blue staining and lectin staining coupled with laser scanning microscopy to indentify its composition and force measurement using atomic force microscopy to measure its stickiness. Batch culture monitoring of the three algal species illustrated varying characteristics in terms of growth pattern, cell concentration and AOM release. The AOM produced by the three algal species comprised mainly biopolymers (e.g., polysaccharides and proteins) but some refractory compounds (e.g., humic-like substances) and other low molecular weight acid and neutral compounds were also found. Biopolymers containing fucose and sulphated functional groups were found in all AOM samples while the presence of other functional groups varied between different species. A large majority (>80%) of the acidic polysaccharide components (in terms of transparent exopolymer particles) were found in the colloidal size range (<0.4 μm). The relative stickiness of AOM substantially varied between algal species and that the cohesion between AOM-coated surfaces was much stronger than the adhesion of AOM on AOM-free surfaces. Overall, the composition as well as the physico-chemical characteristics (e.g., stickiness) of AOM will likely dictate the severity of fouling in membrane systems during algal blooms.

  3. High cell-surface density of HER2 deforms cell membranes

    PubMed Central

    Chung, Inhee; Reichelt, Mike; Shao, Lily; Akita, Robert W.; Koeppen, Hartmut; Rangell, Linda; Schaefer, Gabriele; Mellman, Ira; Sliwkowski, Mark X.

    2016-01-01

    Breast cancers (BC) with HER2 overexpression (referred to as HER2 positive) progress more aggressively than those with normal expression. Targeted therapies against HER2 can successfully delay the progression of HER2-positive BC, but details of how this overexpression drives the disease are not fully understood. Using single-molecule biophysical approaches, we discovered a new effect of HER2 overexpression on disease-relevant cell biological changes in these BC. We found HER2 overexpression causes deformation of the cell membranes, and this in turn disrupts epithelial features by perturbing cell–substrate and cell–cell contacts. This membrane deformation does not require receptor signalling activities, but results from the high levels of HER2 on the cell surface. Our finding suggests that early-stage morphological alterations of HER2-positive BC cells during cancer progression can occur in a physical and signalling-independent manner. PMID:27599456

  4. Efficient black silicon solar cell with a density-graded nanoporous surface: Optical properties, performance limitations, and design rules

    NASA Astrophysics Data System (ADS)

    Yuan, Hao-Chih; Yost, Vernon E.; Page, Matthew R.; Stradins, Paul; Meier, Daniel L.; Branz, Howard M.

    2009-09-01

    We study optical effects and factors limiting performance of our confirmed 16.8% efficiency "black silicon" solar cells. The cells incorporate density-graded nanoporous surface layers made by a one-step nanoparticle-catalyzed etch and reflect less than 3% of the solar spectrum, with no conventional antireflection coating. The cells are limited by recombination in the nanoporous layer which decreases short-wavelength spectral response. The optimum density-graded layer depth is then a compromise between reflectance reduction and recombination loss. Finally, we propose universal design rules for high-efficiency solar cells based on density-graded surfaces.

  5. Methylene blue adsorption by algal biomass based materials: biosorbents characterization and process behaviour.

    PubMed

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2007-08-17

    Dead algal biomass is a natural material that serves as a basis for developing a new family of sorbent materials potentially suitable for many industrial applications. In this work an algal industrial waste from agar extraction process, algae Gelidium and a composite material obtained by immobilization of the algal waste with polyacrylonitrile (PAN) were physical characterized and used as biosorbents for dyes removal using methylene blue as model. The apparent and real densities and the porosity of biosorbents particles were determined by mercury porosimetry and helium picnometry. The methylene blue adsorption in the liquid phase was the method chosen to calculate the specific surface area of biosorbent particles as it seems to reproduce better the surface area accessible to metal ions in the biosorption process than the N2 adsorption-desorption dry method. The porous texture of the biosorbents particles was also studied. Equilibrium isotherms are well described by the Langmuir equation, giving maximum uptake capacities of 171, 104 and 74 mg g(-1), respectively for algae, algal waste and composite material. Kinetic experiments at different initial methylene blue concentrations were performed to evaluate the equilibrium time and the importance of the driving force to overcome mass transfer resistances. The pseudo-first-order and pseudo-second-order kinetic models adequately describe the kinetic data. The biosorbents used in this work proved to be promising materials for removing methylene blue from aqueous solutions.

  6. Modeling the impact of awareness on the mitigation of algal bloom in a lake.

    PubMed

    Misra, A K; Tiwari, P K; Venturino, Ezio

    2016-01-01

    The proliferation of algal bloom in water bodies due to the enhanced concentration of nutrient inflow is becoming a global issue. A prime reason behind this aquatic catastrophe is agricultural runoff, which carries a large amount of nutrients that make the lakes more fertile and cause algal blooms. The only solution to this problem is curtailing the nutrient loading through agricultural runoff. This could be achieved by raising awareness among farmers to minimize the use of fertilizers in their farms. In view of this, in this paper, we propose a mathematical model to study the effect of awareness among the farmers of the mitigation of algal bloom in a lake. The growth rate of awareness among the farmers is assumed to be proportional to the density of algae in the lake. It is further assumed that the presence of awareness among the farmers reduces the inflow rate of nutrients through agricultural runoff and helps to remove the detritus by cleaning the bottom of the lake. The results evoke that raising awareness among farmers may be a plausible factor for the mitigation of algal bloom in the lake. Numerical simulations identify the most critical parameters that influence the blooms and provide indications to possibly mitigate it.

  7. Coupling of Algal Biofuel Production with Wastewater

    PubMed Central

    Panwar, Amit; Bisht, Tara Singh; Tamta, Sushma

    2014-01-01

    Microalgae have gained enormous consideration from scientific community worldwide emerging as a viable feedstock for a renewable energy source virtually being carbon neutral, high lipid content, and comparatively more advantageous to other sources of biofuels. Although microalgae are seen as a valuable source in majority part of the world for production of biofuels and bioproducts, still they are unable to accomplish sustainable large-scale algal biofuel production. Wastewater has organic and inorganic supplements required for algal growth. The coupling of microalgae with wastewater is an effective way of waste remediation and a cost-effective microalgal biofuel production. In this review article, we will primarily discuss the possibilities and current scenario regarding coupling of microalgal cultivation with biofuel production emphasizing recent progress in this area. PMID:24982930

  8. Coupling of algal biofuel production with wastewater.

    PubMed

    Bhatt, Neha Chamoli; Panwar, Amit; Bisht, Tara Singh; Tamta, Sushma

    2014-01-01

    Microalgae have gained enormous consideration from scientific community worldwide emerging as a viable feedstock for a renewable energy source virtually being carbon neutral, high lipid content, and comparatively more advantageous to other sources of biofuels. Although microalgae are seen as a valuable source in majority part of the world for production of biofuels and bioproducts, still they are unable to accomplish sustainable large-scale algal biofuel production. Wastewater has organic and inorganic supplements required for algal growth. The coupling of microalgae with wastewater is an effective way of waste remediation and a cost-effective microalgal biofuel production. In this review article, we will primarily discuss the possibilities and current scenario regarding coupling of microalgal cultivation with biofuel production emphasizing recent progress in this area.

  9. Algal diseases: spotlight on a black box.

    PubMed

    Gachon, Claire M M; Sime-Ngando, Télesphore; Strittmatter, Martina; Chambouvet, Aurélie; Kim, Gwang Hoon

    2010-11-01

    Like any other living organisms, algae are plagued by diseases caused by fungi, protists, bacteria or viruses. As aquaculture continues to rise worldwide, pathogens of nori or biofuel sources are becoming a significant economic burden. Parasites are also increasingly being considered of equal importance with predators for ecosystem functioning. Altered disease patterns in disturbed environments are blamed for sudden extinctions, regime shifts, and spreading of alien species. Here we review the biodiversity and impact of pathogens and parasites of aquatic primary producers in freshwater and marine systems. We also cover recent advances on algal defence reactions, and discuss how emerging technologies can be used to reassess the profound, multi-faceted, and so far broadly-overlooked influence of algal diseases on ecosystem properties.

  10. A Comparison of Spatial Analysis Methods for the Construction of Topographic Maps of Retinal Cell Density

    PubMed Central

    Garza-Gisholt, Eduardo; Hemmi, Jan M.; Hart, Nathan S.; Collin, Shaun P.

    2014-01-01

    Topographic maps that illustrate variations in the density of different neuronal sub-types across the retina are valuable tools for understanding the adaptive significance of retinal specialisations in different species of vertebrates. To date, such maps have been created from raw count data that have been subjected to only limited analysis (linear interpolation) and, in many cases, have been presented as iso-density contour maps with contour lines that have been smoothed ‘by eye’. With the use of stereological approach to count neuronal distribution, a more rigorous approach to analysing the count data is warranted and potentially provides a more accurate representation of the neuron distribution pattern. Moreover, a formal spatial analysis of retinal topography permits a more robust comparison of topographic maps within and between species. In this paper, we present a new R-script for analysing the topography of retinal neurons and compare methods of interpolating and smoothing count data for the construction of topographic maps. We compare four methods for spatial analysis of cell count data: Akima interpolation, thin plate spline interpolation, thin plate spline smoothing and Gaussian kernel smoothing. The use of interpolation ‘respects’ the observed data and simply calculates the intermediate values required to create iso-density contour maps. Interpolation preserves more of the data but, consequently includes outliers, sampling errors and/or other experimental artefacts. In contrast, smoothing the data reduces the ‘noise’ caused by artefacts and permits a clearer representation of the dominant, ‘real’ distribution. This is particularly useful where cell density gradients are shallow and small variations in local density may dramatically influence the perceived spatial pattern of neuronal topography. The thin plate spline and the Gaussian kernel methods both produce similar retinal topography maps but the smoothing parameters used may affect

  11. A comparison of spatial analysis methods for the construction of topographic maps of retinal cell density.

    PubMed

    Garza-Gisholt, Eduardo; Hemmi, Jan M; Hart, Nathan S; Collin, Shaun P

    2014-01-01

    Topographic maps that illustrate variations in the density of different neuronal sub-types across the retina are valuable tools for understanding the adaptive significance of retinal specialisations in different species of vertebrates. To date, such maps have been created from raw count data that have been subjected to only limited analysis (linear interpolation) and, in many cases, have been presented as iso-density contour maps with contour lines that have been smoothed 'by eye'. With the use of stereological approach to count neuronal distribution, a more rigorous approach to analysing the count data is warranted and potentially provides a more accurate representation of the neuron distribution pattern. Moreover, a formal spatial analysis of retinal topography permits a more robust comparison of topographic maps within and between species. In this paper, we present a new R-script for analysing the topography of retinal neurons and compare methods of interpolating and smoothing count data for the construction of topographic maps. We compare four methods for spatial analysis of cell count data: Akima interpolation, thin plate spline interpolation, thin plate spline smoothing and Gaussian kernel smoothing. The use of interpolation 'respects' the observed data and simply calculates the intermediate values required to create iso-density contour maps. Interpolation preserves more of the data but, consequently includes outliers, sampling errors and/or other experimental artefacts. In contrast, smoothing the data reduces the 'noise' caused by artefacts and permits a clearer representation of the dominant, 'real' distribution. This is particularly useful where cell density gradients are shallow and small variations in local density may dramatically influence the perceived spatial pattern of neuronal topography. The thin plate spline and the Gaussian kernel methods both produce similar retinal topography maps but the smoothing parameters used may affect the outcome.

  12. T-cell proliferation and forkhead box P3 expression in human T cells are dependent on T-cell density: physics of a confined space?

    PubMed

    Bernardo, David; Al-Hassi, Hafid O; Mann, Elizabeth R; Tee, Cheng T; Murugananthan, Aravinth U; Peake, Simon T C; Hart, Ailsa L; Knight, Stella C

    2012-03-01

    T-cell proliferation rates in vitro depend on factors including initial T-cell number, dose of stimulus, culture time, and available physical space. The role of forkhead box P3 (FoxP3) in the identification of T cells with a regulatory phenotype remains controversial in humans. Through 5-carboxyfluorescein diacetate succinimidyl ester labeling of human T cells and subsequent culture of different numbers of T cells and antigen-presenting cells (APC), we studied proliferative T-cell responses and FoxP3 expression in divided T cells. T-cell proliferation rates depended on initial T-cell/APC numbers. Proliferation rates decreased when high initial T-cell numbers were increased. FoxP3 expression was expressed exclusively in virtually all divided T cells cultured at high T-cell densities, irrespective of their CD4 nature or cytokine content, and was coexpressed with T-bet. However, when T cells were cultured on larger surfaces or at lower initial numbers, FoxP3 expression was not induced in divided T cells, even when most of the cells had undergone cell division. FoxP3(+) T cells generated at high cell densities did not elicit a suppressive phenotype and FoxP3 expression was subsequently lost in time when the stimulus was removed. Therefore, caution should be observed in the use of FoxP3 expression to identify regulatory T cells in humans because its expression may be only a consequence of activation status in a restricted environment.

  13. Reactor-scale cultivation of the hyperthermophilic methanarchaeon Methanococcus jannaschii to high cell densities.

    PubMed

    Mukhopadhyay, B; Johnson, E F; Wolfe, R S

    1999-11-01

    For the hyperthermophilic and barophilic methanarchaeon Methanococcus jannaschii, we have developed a medium and protocols for reactor-scale cultivation that improved the final cell yield per liter from approximately 0.5 to approximately 7.5 g of packed wet cells ( approximately 1.8 g dry cell mass) under autotrophic growth conditions and to approximately 8.5 g of packed wet cells ( approximately 2 g dry cell mass) with yeast extract (2 g liter(-1)) and tryptone (2 g liter(-1)) as medium supplements. For growth in a sealed bottle it was necessary to add Se to the medium, and a level of 2 microM for added Se gave the highest final cell yield. In a reactor M. jannaschii grew without added Se in the medium; it is plausible that the cells received Se as a contaminant from the reactor vessel and the H(2)S supply. But, for the optimal performance of a reactor culture, an addition of Se to a final concentration of 50 to 100 microM was needed. Also, cell growth in a reactor culture was inhibited at much higher Se concentrations. These observations and the data from previous work with methanogen cell extracts (B. C. McBride and R. S. Wolfe, Biochemistry 10:4312-4317, 1971) suggested that from a continuously sparged reactor culture Se was lost in the exhaust gas as volatile selenides, and this loss raised the apparent required level of and tolerance for Se. In spite of having a proteinaceous cell wall, M. jannaschii withstood an impeller tip speed of 235.5 cms(-1), which was optimal for achieving high cell density and also was the higher limit for the tolerated shear rate. The organism secreted one or more acidic compounds, which lowered pH in cultures without pH control; this secretion continued even after cessation of growth.

  14. Increasing Vero viable cell densities for yellow fever virus production in stirred-tank bioreactors using serum-free medium.

    PubMed

    Mattos, Diogo A; Silva, Marlon V; Gaspar, Luciane P; Castilho, Leda R

    2015-08-20

    In this work, changes in Vero cell cultivation methods have been employed in order to improve cell growth conditions to obtain higher viable cell densities and to increase viral titers. The propagation of the 17DD yellow fever virus (YFV) in Vero cells grown on Cytodex I microcarriers was evaluated in 3-L bioreactor vessels. Prior to the current changes, Vero cells were repeatedly displaying insufficient microcarrier colonization. A modified cultivation process with four changes has resulted in higher cell densities and higher virus titers than previously observed for 17DD YFV.

  15. The role of cell size in density gradient electrophoretic separation of mouse leukemia cells according to position in the cell cycle

    NASA Technical Reports Server (NTRS)

    Plank, L. D.; Kunze, M. E.; Todd, P. W.

    1985-01-01

    Cultured mouse leukemia cells line L5178Y were subjected to upward electrophoresis in a density gradient and the slower migrating cell populations were enriched in G2 cells. It is indicated that this cell line does not change electrophoretic mobility through the cell cycle. The possibility that increased sedimentation downward on the part of the larger G2 cells caused this separation was explored. Two different cell populations were investigated. The log phase population was found to migrate upward faster than the G2 population, and a similar difference between their velocities and calculated on the basis of a 1 um diameter difference between the two cell populations. The G2 and G1 enriched populations were isolated by Ficoll density gradient sedimentation. The bottom fraction was enriched in G2 cells and the top fraction was enriched with G1 cells, especially when compared with starting materials. The electrophoretic mobilities of these two cell populations did not differ significantly from one another. Cell diameter dependent migration curves were calculated and were found to be different. Families of migration curves that differ when cell size is considered as a parameter are predicted.

  16. Copper desorption from Gelidium algal biomass.

    PubMed

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2007-04-01

    Desorption of divalent copper from marine algae Gelidium sesquipedale, an algal waste (from agar extraction industry) and a composite material (the algal waste immobilized in polyacrylonitrile) was studied in a batch system. Copper ions were first adsorbed until saturation and then desorbed by HNO(3) and Na(2)EDTA solutions. Elution efficiency using HNO(3) increases as pH decreases. At pH=1, for a solid to liquid ratio S/L=4gl(-1), elution efficiency was 97%, 95% and 88%, the stoichiometric coefficient for the ionic exchange, 0.70+/-0.02, 0.73+/-0.05 and 0.76+/-0.06 and the selectivity coefficient, 0.93+/-0.07, 1.0+/-0.3 and 1.1+/-0.3, respectively, for algae Gelidium, algal waste and composite material. Complexation of copper ions by EDTA occurs in a molar proportion of 1:1 and the elution efficiency increases with EDTA concentration. For concentrations of 1.4, 0.88 and 0.57 mmoll(-1), the elution efficiency for S/L=4gl(-1), was 91%, 86% and 78%, respectively, for algae Gelidium, algal waste and composite material. The S/L ratio, in the range 1-20gl(-1), has little influence on copper recovery by using 0.1M HNO(3). Desorption kinetics was very fast for all biosorbents. Kinetic data using HNO(3) as eluant were well described by the mass transfer model, considering the average metal concentration in the solid phase and the equilibrium relationship given by the mass action law. The homogeneous diffusion coefficient varied between 1.0 x 10(-7)cm(2)s(-1) for algae Gelidium and 3.0 x 10(-7)cm(2)s(-1) for the composite material.

  17. Minimally oxidized low-density lipoprotein induces tissue factor expression in cultured human endothelial cells.

    PubMed Central

    Drake, T. A.; Hannani, K.; Fei, H. H.; Lavi, S.; Berliner, J. A.

    1991-01-01

    Oxidatively modified low-density lipoprotein is present in atherosclerotic lesions and has been proposed to play an important role in atherogenesis through its biologic effects on vascular cells. This study examined the effects of minimally oxidized preparations of LDL (MM-LDL) on tissue factor (TF) expression by cultured human endothelial cells. Low-density lipoprotein purified from normal donors was modified by exposure to iron or by prolonged storage, resulting in levels of thiobarbituric acid-reacting substances of approximately 2.5 to 4 nmoles/mg cholesterol. Preparations had less than 2.5 pg of endotoxin per microgram LDL and had no intrinsic procoagulant activity. This form of modified but not native LDL induced TF expression in endothelial cells in a time- and dose-dependent manner. Peak TF coagulant activity in cells exposed to 40 micrograms/ml MM-LDL were observed at 4 to 6 hours, and ranged from 50 to 500 pg/10(5) cells, compared with less than 10 pg/10(5) cells exposed to native LDL. Northern blot analysis showed TF mRNA levels to increase approximately 30-fold with exposure to MM-LDL for 2 hours. Induction of TF activity was dependent on the concentration of MM-LDL from 1 microgram/ml to 80 micrograms/ml, a range in which cell viability and morphology were unaffected. The findings suggest that minimally oxidized LDL may be a local mediator promoting thrombosis in atherosclerotic lesions. Images Figure 1 PMID:2000938

  18. Characterization of bottom ice algal and detrital spectral absorption properties in first-year sea ice of an Arctic polynya

    NASA Astrophysics Data System (ADS)

    Mundy, C.; Gosselin, M.; Nozais, C.; Simard, M.

    2009-12-01

    Little information exists on the spectral absorption properties of algal and detrital matter in sea ice. During the International North Water polynya study, we collected a large dataset on ice algal spectral absorption characteristics within the bottom 2 to 4 cm of first-year sea ice from April to June 1998. The data compared surprisingly well with select phytoplankton models, given that the models were extrapolated well beyond their limits to ice algal chlorophyll a (Chl a) concentrations that ranged up to 2000 mg m-3. However, a strong packaging effect was apparent at Chl a concentrations >500 mg m-3, which tended to decrease the Chl a specific algal absorption coefficient relative to model predictions. Diatoms dominated the ice algae community for most of the period and subsequently, controlled absorption characteristics. Although not conclusive, an outlier dominated by nanoflagellates did show an increase in the Chl a specific algal absorption coefficient, demonstrating the decrease in packaging effect associated with the smaller cell size. Seasonal progression in ice algal spectral absorption revealed a change in pigment composition from strong absorption >500 nm, indicative of photosynthetic accessory pigments, to strong absorption between 450 nm to 500 nm, indicative of photoprotective pigments. Furthermore, the ratio of phytoplankton absorption at 490:470 nm regressed significantly with time (positive) and ice thickness (negative) throughout the study period, suggesting a continual photoacclimation of the ice algal community to increasing transmitted irradiance. The results of our study show that measurements of ice algal spectral absorption properties will not only improve their parameterization in sea ice bio-optical models, but can provide information on both taxonomic composition and physiological state.

  19. Evaluation of nutritive value and in vitro rumen fermentation gas accumulation of de-oiled algal residues

    PubMed Central

    2014-01-01

    Background Algae are widely recognized for their high oil content and for exponentially accumulating biomass with particular potential to provide single cell protein for human consumption or animal feed. It is believed that along with biodiesel from algae, the high protein de-oiled algal residue may become an alternative feed supplement option in the future. This study was conducted to investigate de-oiled algal residue obtained from the common Chlorella species, Thalassiosira weissflogii, Selenarstrum capricornutum, Scenedesmus sp., and Scenedesmus dimorphus for assessment as potential feed supplements for ruminants by comparing with soybean (Glycine max) meal and alfalfa (Medicago sativa) hay. Results With the exception of T. weissflogii, algal residue had higher concentrations of Cu, Zn, and Mn and lower concentration of Ca, Mg, and K than soybean meal and alfalfa hay. The algal residue CP (crude protein) concentrations ranged from 140 to 445 g/kg DM and varied among the de-oiled residues. In vitro rumen fermentation gas accumulation curves indicated that algal biomass degradation potential was less than that of soybean meal or alfalfa hay by up to 41.7%. The gas production curve, interpreted with a dual pool logistic model, confirmed that the fraction sizes for fast fermenting and slow fermenting of de-oiled algal residues were smaller than those in soybean meal and alfalfa hay, and the fermenting rate of the fractions was also low. Conclusions Inferior in vitro rumen gas accumulation from the five de-oiled algal residues suggests that these algal byproducts are less degradable in the rumen. PMID:25093078

  20. Development of silver-zinc cells of improved cycle life and energy density

    NASA Astrophysics Data System (ADS)

    Serenyi, Roberto; James, Stanley D.

    1994-03-01

    Substantial increases in the cost effectiveness and range of naval underwater vehicles are possible by virtue of advances made, in this program, to silver-zinc, vehicle propulsion batteries. To improve battery cycle life and energy density, electropermeable membranes (EPM's) were used as additives and/or as coatings for the negative electrodes and as coatings for conventional separator materials. Also, bismuth oxide was tested as an additive to the negative electrodes and P2291-40/20, a radiation-grafted polyethylene film, as a separator used in conjunction with silver-treated cellophane. EPM's used as negative electrode additives and also as coatings for Celgard 2500 microporous polypropylene greatly improved cells. Cells with EPM's used as coatings for the negative electrodes failed rapidly because of an error in formulation. Cells with 10 percent bismuth oxide in the negative electrodes exhibited substantially lower capacity than the standard cells and were removed from the test. Cells with radiation-grafted polyethylene separators provided fewer cycles than the standard cells, with 5 percent higher capacity and 6 percent lower utilization of active materials by cycle 60. However, the slightly better capacity of these cells, realized due to the additional space available for active materials, does not compensate for their generally unimpressive performance.

  1. High-density cell systems incorporating polymer microspheres as microenvironmental regulators in engineered cartilage tissues.

    PubMed

    Solorio, Loran D; Vieregge, Eran L; Dhami, Chirag D; Alsberg, Eben

    2013-06-01

    To address the significant clinical need for tissue-engineered therapies for the repair and regeneration of articular cartilage, many systems have recently been developed using bioactive polymer microspheres as regulators of the chondrogenic microenvironment within high-density cell cultures. In this review, we highlight various densely cellular systems utilizing polymer microspheres as three-dimensional (3D) structural elements within developing engineered cartilage tissue, carriers for cell expansion and delivery, vehicles for spatiotemporally controlled growth factor delivery, and directors of cell behavior via regulation of cell-biomaterial interactions. The diverse systems described herein represent a shift from the more traditional tissue engineering approach of combining cells and growth factors within a biomaterial scaffold, to the design of modular systems that rely on the assembly of cells and bioactive polymer microspheres as building blocks to guide the creation of articular cartilage. Cell-based assembly of 3D microsphere-incorporated structures represents a promising avenue for the future of tissue engineering.

  2. Liquid transportation fuels from algal oils

    NASA Astrophysics Data System (ADS)

    Chen, Daichuan

    Liquid transportation fuels from renewable sources are becoming more prominent and important in modem society. Processing of hydrocarbon oils from algae has not been studied in detail in the past, so components which have been proposed for incorporation in algal oils via genetic engineering, such as cuparene, farnesene, phytol and squalene, have been subjected to processing via catalytic cracking in a pulse reactor at different temperatures. The cracking results showed that liquid products contained numerous high octane molecules which make it feasible for use in automobiles. Additionally, canola oil, chosen as an algal oil model compound, was studied as a feed for catalytic cracking in a fixed-bed reactor at atmospheric pressure over different types of zeolites. The results showed that MFI catalysts gave the highest yield of gasoline range products and lowest coke formation. Gallium loaded MFI zeolites increased the total aromatics yield for the canola oil cracking relative to the acid form of the zeolite. Finally, algal oils were cracked on several selected zeolites, and the results showed the same trend as canola oil cracking. MFI gave the highest gasoline yield (43.8 wt%) and lowest coke (4.7 wt%). The total aromatics yield from algae oil cracking is improved 7.8 wt% when MFI is loaded with gallium.

  3. Effects of Electromagnetic Stimulation on Cell Density and Neural Markers in Murine Enteric Cell Cultures

    NASA Astrophysics Data System (ADS)

    Carreón-Rodríguez, A.; Belkind-Gerson, J.; Serrano-Luna, G.; Cañedo-Dorantes, L.

    2008-08-01

    Availability of adult stem cells from several organs like bone marrow, umbilical cord blood or peripheral blood has become a powerful therapeutic tool for many chronic diseases. Potential of adult stem cells for regeneration extents to other tissues among them the nervous system. However two obstacles should be resolved before such cells could be currently applied in clinical practice: a) slow growth rate and b) ability to form enough dense colonies in order to populate a specific injury or cellular deficiency. Many approaches have been explored as genetic differentiation programs, growth factors, and supplemented culture media, among others. Electromagnetic field stimulation of differentiation, proliferation, migration, and particularly on neurogenesis is little known. Since the biological effects of ELF-EMF are well documented, we hypothesize ELF-EMF could affect growth and maturation of stem cells derived of enteric tissue.

  4. Effects of Electromagnetic Stimulation on Cell Density and Neural Markers in Murine Enteric Cell Cultures

    SciTech Connect

    Carreon-Rodriguez, A.; Belkind-Gerson, J.; Serrano-Luna, G.; Canedo-Dorantes, L.

    2008-08-11

    Availability of adult stem cells from several organs like bone marrow, umbilical cord blood or peripheral blood has become a powerful therapeutic tool for many chronic diseases. Potential of adult stem cells for regeneration extents to other tissues among them the nervous system. However two obstacles should be resolved before such cells could be currently applied in clinical practice: a) slow growth rate and b) ability to form enough dense colonies in order to populate a specific injury or cellular deficiency. Many approaches have been explored as genetic differentiation programs, growth factors, and supplemented culture media, among others. Electromagnetic field stimulation of differentiation, proliferation, migration, and particularly on neurogenesis is little known. Since the biological effects of ELF-EMF are well documented, we hypothesize ELF-EMF could affect growth and maturation of stem cells derived of enteric tissue.

  5. Simultaneous removal of harmful algal blooms and microcystins using microorganism- and chitosan-modified local soil.

    PubMed

    Li, Hong; Pan, Gang

    2015-05-19

    Cyanobacterial harmful algal blooms (cyano-HAB) and microcystins (MCs) can cause a potential threat to public health. Here, a method for simultaneous removal of cyano-HAB and MCs was developed using chitosan-modified local soil (MLS) flocculation plus microorganism-modified soil capping. The experiment was conducted in simulated columns containing algal water collected from Lake Taihu (China). More than 90% of algal cells and intracellular MCs were flocculated and removed from water using chitosan-MLS and the sunken flocs were treated by different capping materials including Pseudomonas sp. An18 modified local soil. During 40 days of incubation, dissolved MC-LR and MC-RR showed 10-fold increase in the flocculation-only system. The increase of MC-LR and MC-RR in water was reduced by 30 and 70% in soil capping treatments; however, the total content of MCs in the sediment-water column remained similar to that in the control and flocculation only systems. In contrast, both dissolved MCs and total MCs were reduced by 90% in Pseudomonas sp. An18 modified soil capping treatment. The high performance of toxin decomposition was due to the combined effects of flocculation and MC-degrading bacteria that embedded in the capping material, which prevents dilution of bacteria biomass, concentrates algal cells, confines released toxins, and enhances toxin biodegradation.

  6. Progress on lipid extraction from wet algal biomass for biodiesel production.

    PubMed

    Ghasemi Naghdi, Forough; González González, Lina M; Chan, William; Schenk, Peer M

    2016-11-01

    Lipid recovery and purification from microalgal cells continues to be a significant bottleneck in biodiesel production due to high costs involved and a high energy demand. Therefore, there is a considerable necessity to develop an extraction method which meets the essential requirements of being safe, cost-effective, robust, efficient, selective, environmentally friendly, feasible for large-scale production and free of product contamination. The use of wet concentrated algal biomass as a feedstock for oil extraction is especially desirable as it would avoid the requirement for further concentration and/or drying. This would save considerable costs and circumvent at least two lengthy processes during algae-based oil production. This article provides an overview on recent progress that has been made on the extraction of lipids from wet algal biomass. The biggest contributing factors appear to be the composition of algal cell walls, pre-treatments of biomass and the use of solvents (e.g. a solvent mixture or solvent-free lipid extraction). We compare recently developed wet extraction processes for oleaginous microalgae and make recommendations towards future research to improve lipid extraction from wet algal biomass.

  7. Factors controlling the proliferative rate, final cell density, and life span of bovine vascular smooth muscle cells in culture

    PubMed Central

    1981-01-01

    Low density vascular smooth muscle (VSM) cell cultures maintained on extracellular-matrix(ECM)-coated dishes and plated in the presence of either plasma or serum will proliferate actively when serum-containing medium is replaced by a synthetic medium supplemented with three factors: high density lipoprotein (HDL, 250 micrograms protein/ml); insulin (2.5 micrograms/ml) or somatomedin C (10 ng/ml); and fibroblast growth factor (FGF, 100 ng/ml) or epidermal growth factor (EGF, 50 ng/ml). The omission of any of these three factors from the synthetic medium results in a lower growth rate of the cultures, as well as in a lower final cell density once cultures reach confluence. When cells are plated in the total absence of serum, transferrin (10 micrograms/ml) is also required to induce optimal cell growth. The effects of the substrate and medium supplements on the life span of VSM cultures have also been analyzed. Cultures maintained on plastic and exposed to medium supplemented with 5% bovine serum underwent 15 generations. However, when maintained on ECM-coated dishes the serum-fed cultures had a life span of at least 88 generations. Likewise, when cultures were maintained in a synthetic medium supplemented with HDL and either FGF or EGF, an effect on the tissue culture life span by the substrate was observed. Cultures maintained on plastic underwent 24 generations, whereas those maintained on ECM-coated dishes could be passaged repeatedly for 58 generations. These experiments demonstrate the influence of the ECM-substrate only in promoting cell growth but also in increasing the longevity of the cultures. PMID:6454694

  8. A novel rat tail collagen type-I gel for the cultivation of human articular chondrocytes in low cell density.

    PubMed

    Muller-Rath, R; Gavénis, K; Andereya, S; Mumme, T; Schmidt-Rohlfing, B; Schneider, U

    2007-12-01

    Collagen type-I matrix systems have gained growing importance as a cartilage repair device. However, most of the established matrix systems use collagen type-I of bovine origin seeded in high cell densities. Here we present a novel collagen type-I gel system made of rat tail collagen for the cultivation of human chondrocytes in low cell densities. Rat tail collagen type-I gel (CaReS, Arthro Kinetics, Esslingen, Germany) was seeded with human passage 2 chondrocytes in different cell densities to evaluate the optimal cell number. In vitro, the proliferation factor of low density cultures was more than threefold higher compared with high density cultures. After 6 weeks of in vitro cultivation, freshly prepared chondrocytes with an initial cell density of 2x10(5) cells/mL showed a proliferation factor of 33. A cell density of 2x10(5) cells/mL was chosen for in vitro and in vivo cultivation using the common nude mouse model as an in vivo system. Chondrocytes stayed viable as a Live/Dead fluorescence assay and TUNEL staining revealed. During in vitro cultivation, passage 0 cells partly dedifferentiated morphologically. In vivo, passage 0 cells maintained the chondrocyte phenotype and demonstrated an increased synthesis of collagen type-II protein and gene expression compared to passage 2 cells. Passage 2 cells did not redifferentiate in vivo. Cultivating a cell-seeded collagen gel of bovine origin as a control (AtelocollagenTM, Koken, Tokyo, Japan) did not lead to superior results with regard to cell morphology, col-II protein production and col-II gene expression. With the CaReS collagen gel system the best quality of repair tissue was obtained by seeding freshly isolated chondrocytes.

  9. Decreased vascular smooth muscle cell density in medial degeneration of human abdominal aortic aneurysms.

    PubMed Central

    López-Candales, A.; Holmes, D. R.; Liao, S.; Scott, M. J.; Wickline, S. A.; Thompson, R. W.

    1997-01-01

    Abdominal aortic aneurysms (AAAs) are characterized by structural deterioration of the aortic wall leading to progressive aortic dilatation and eventual rupture. The histopathological changes in AAAs are particularly evident within the elastic media, which is normally dominated by vascular smooth muscle cells (SMCs). To determine whether a decrease in vascular SMCs contributes to medial degeneration, we measured SMC density in 21 normal and pathological human abdominal aortic tissue specimens using immunohistochemistry for alpha-SMC actin and direct cell counts (medial SMCs per high-power field (HPF)). Medial SMC density was not significantly different between normal aorta (n = 5; 199.5 +/- 14.9 SMCs/HPF) and atherosclerotic occlusive disease (n = 6; 176.4 +/- 13.9 SMCs/HPF), but it was reduced by 74% in AAA (n = 10; 50.9 +/- 6.1 SMCs/HPF; P < 0.01 versus normal aorta). Light and electron microscopy revealed no evidence of overt cellular necrosis, but SMCs in AAAs exhibited ultrastructural changes consistent with apoptosis. Using in situ end-labeling (ISEL) of fragmented DNA to detect apoptotic cells, up to 30% of aortic wall cells were ISEL positive in AAAs. By double-labeling techniques, many of these cells were alpha-actin-positive SMCs distributed throughout the degenerative media. In contrast, ISEL-positive cells were observed only within the intimal plaque in atherosclerotic occlusive disease. The amount of p53 protein detected by immunoblotting was increased nearly fourfold in AAA compared with normal aorta and atherosclerotic occlusive disease (P < 0.01), and immunoreactive p53 was localized to lymphocytes and residual SMCs in the aneurysm wall. Using reverse transcription polymerase chain reaction assays a substantial amount of p53 mRNA expression was observed in AAAs. These results demonstrate that medial SMC density is significantly decreased in human AAA tissues associated with evidence of SMC apoptosis and increased production of p53, a potential

  10. Utilization of ascites plasma very low density lipoprotein triglycerides by Ehrlich cells.

    PubMed

    Brenneman, D E; Spector, A A

    1974-07-01

    Much of the lipid present in the ascites plasma in which Ehrlich cells grow is contained in very low density lipoproteins (VLDL). Chemical measurements indicated that triglycerides were taken up by the cells during in vitro incubation with ascites VLDL. When tracer amounts of radioactive triolein were incorporated into the ascites VLDL, the percentage uptakes of glyceryl tri[1-(14)C]oleate and triglycerides measured chemically were similar. The cells also took up [2-(3)H]glyceryl trioleate that was added to VLDL, but the percentage of available (3)H recovered in the cell lipids was 30-40% less than that of (1 4)C from glyceryl tri[1-(1 4)C]oleate. This difference was accounted for by water-soluble (3)H that accumulated in the incubation medium, suggesting that extensive hydrolysis accompanied the uptake of VLDL triglycerides. Radioactive fatty acids derived from the VLDL triglycerides were incorporated into cell phospholipids, glycerides, and free fatty acids, and they also were oxidized to CO(2). Triglyceride utilization increased as the VLDL concentration was raised. These results suggest that one function of the ascites plasma VLDL may be to supply fatty acid to the Ehrlich cells and that the availability of fatty acid to this tumor is determined in part by the ascites plasma VLDL concentration. Although Ehrlich cells incorporate almost no free glycerol into triglycerides, considerable amounts of [2-(3)H]glyceryl trioleate radioactivity were recovered in cell triglycerides. This indicates that at least some VLDL triglycerides were taken up intact. The net uptake of VLDL protein and cholesterol was very small relative to the triglyceride uptake, suggesting that intact triglycerides are transferred from the ascites VLDL to the Ehrlich cells and that hydrolysis occurs after the triglyceride is associated with the cells.

  11. High-density MEA recordings unveil the dynamics of bursting events in Cell Cultures.

    PubMed

    Lonardoni, Davide; Di Marco, Stefano; Amin, Hayder; Maccione, Alessandro; Berdondini, Luca; Nieus, Thierry

    2015-08-01

    High density multielectrode arrays (MEAs) based on CMOS technology (CMOS-MEAs) can simultaneously record extracellular spiking activity in neuronal cultures from 4096 closely spaced microelectrodes. This allows for a finer investigation of neuronal network activity compared to conventional MEAs with a few tens of electrodes. However, the sensing properties of these devices differ. To highlight this aspect, here we investigate and discuss the differences observed when quantifying spontaneous synchronized bursting events (SBEs) in datasets acquired with conventional MEAs and high-density MEAs from comparable hippocampal cultures. We found that datasets acquired with high-density MEAs exhibit collective dynamics similar to conventional arrays, but are characterized by a higher percentage of random spikes, i.e. spikes that are not part of a burst, most probably resulting from the larger recording capability. Additionally, the percentage of electrodes that record a burst is remarkably small on high-density MEAs compared to what can be observed on conventional MEAs and SBEs appear to be propagating in time across the electrode array, by involving shorter sequences of spikes per electrode. Overall, these results highlight a lower level of network synchronization involved in SBEs compared to what has been debated for several decades based on conventional MEA recordings from cell cultures.

  12. Boosting Power Density of Microbial Fuel Cells with 3D Nitrogen-Doped Graphene Aerogel Electrode.

    PubMed

    Yang, Yang; Liu, Tianyu; Zhu, Xun; Zhang, Feng; Ye, Dingding; Liao, Qiang; Li, Yat

    2016-08-01

    A 3D nitrogen-doped graphene aerogel (N-GA) as an anode material for microbial fuel cells (MFCs) is reported. Electron microscopy images reveal that the N-GA possesses hierarchical porous structure that allows efficient diffusion of both bacterial cells and electron mediators in the interior space of 3D electrode, and thus, the colonization of bacterial communities. Electrochemical impedance spectroscopic measurements further show that nitrogen doping considerably reduces the charge transfer resistance and internal resistance of GA, which helps to enhance the MFC power density. Importantly, the dual-chamber milliliter-scale MFC with N-GA anode yields an outstanding volumetric power density of 225 ± 12 W m(-3) normalized to the total volume of the anodic chamber (750 ± 40 W m(-3) normalized to the volume of the anode). These power densities are the highest values report for milliliter-scale MFCs with similar chamber size (25 mL) under the similar measurement conditions. The 3D N-GA electrode shows great promise for improving the power generation of MFC devices.

  13. Boosting Power Density of Microbial Fuel Cells with 3D Nitrogen‐Doped Graphene Aerogel Electrode

    PubMed Central

    Yang, Yang; Liu, Tianyu; Zhang, Feng; Ye, Dingding; Liao, Qiang

    2016-01-01

    A 3D nitrogen‐doped graphene aerogel (N‐GA) as an anode material for microbial fuel cells (MFCs) is reported. Electron microscopy images reveal that the N‐GA possesses hierarchical porous structure that allows efficient diffusion of both bacterial cells and electron mediators in the interior space of 3D electrode, and thus, the colonization of bacterial communities. Electrochemical impedance spectroscopic measurements further show that nitrogen doping considerably reduces the charge transfer resistance and internal resistance of GA, which helps to enhance the MFC power density. Importantly, the dual‐chamber milliliter‐scale MFC with N‐GA anode yields an outstanding volumetric power density of 225 ± 12 W m−3 normalized to the total volume of the anodic chamber (750 ± 40 W m−3 normalized to the volume of the anode). These power densities are the highest values report for milliliter‐scale MFCs with similar chamber size (25 mL) under the similar measurement conditions. The 3D N‐GA electrode shows great promise for improving the power generation of MFC devices. PMID:27818911

  14. Type, Density, and Location of Immune Cells Within Human Colorectal Tumors Predict Clinical Outcome

    NASA Astrophysics Data System (ADS)

    Galon, Jérôme; Costes, Anne; Sanchez-Cabo, Fatima; Kirilovsky, Amos; Mlecnik, Bernhard; Lagorce-Pagès, Christine; Tosolini, Marie; Camus, Matthieu; Berger, Anne; Wind, Philippe; Zinzindohoué, Franck; Bruneval, Patrick; Cugnenc, Paul-Henri; Trajanoski, Zlatko; Fridman, Wolf-Herman; Pagès, Franck

    2006-09-01

    The role of the adaptive immune response in controlling the growth and recurrence of human tumors has been controversial. We characterized the tumor-infiltrating immune cells in large cohorts of human colorectal cancers by gene expression profiling and in situ immunohistochemical staining. Collectively, the immunological data (the type, density, and location of immune cells within the tumor samples) were found to be a better predictor of patient survival than the histopathological methods currently used to stage colorectal cancer. The results were validated in two additional patient populations. These data support the hypothesis that the adaptive immune response influences the behavior of human tumors. In situ analysis of tumor-infiltrating immune cells may therefore be a valuable prognostic tool in the treatment of colorectal cancer and possibly other malignancies.

  15. High cell density cultivation of Brevibacterium linens and formation of proteinases and lipase.

    PubMed

    Adamitsch, Bernhard F; Karner, Ferdinand; Hampel, Werner A

    2003-05-01

    Brevibacterium linens forms hydrolytic enzymes which can be used to accelerate the ripening of cheese without causing bitterness. B. linens ATCC 9172 was grown to a high cell density (50 g dry wt l-1 after 60 h) in a mineral medium containing lactic acid, soy-peptone and ammonium sulphate by applying a continuous feed of nutrients. The maximal activities of L-leucine aminopeptidase and cell-associated proteinase were 286 U l-1 and 202 U l-1, respectively. The cell-associated lipolytic activity exhibited a strong and sudden increase at 46 h, resulting in a maximum of 9.5 U g-1 dry wt; thus the volumetric productivity of proteolytic and lipolytic activity was 4220 U l-1 h-1 and 7.3 U l-1 h-1, respectively.

  16. Decreased lung carcinoma cell density on select polymer nanometer surface features for lung replacement therapies.

    PubMed

    Zhang, Lijuan; Chun, Young Wook; Webster, Thomas J

    2010-05-13

    Poly(lactic-co-glycolic) acid (PLGA) has been widely used as a biomaterial in regenerative medicine because of its biocompatibility and biodegradability properties. Previous studies have shown that cells (such as bladder smooth muscle cells, chondrocytes, and osteoblasts) respond differently to nanostructured PLGA surfaces compared with nanosmooth surfaces. The purpose of the present in vitro research was to prepare PLGA films with various nanometer surface features and determine whether lung cancer epithelial cells respond differently to such topographies. To create nanosurface features on PLGA, different sized (190 nm, 300 nm, 400 nm, and 530 nm diameter) polystyrene beads were used to cast polydimethylsiloxane (PDMS) molds which were used as templates to create nanofeatured PLGA films. Atomic force microscopy (AFM) images and root mean square roughness (RMS) values indicated that the intended spherical surface nanotopographies on PLGA with RMS values of 2.23, 5.03, 5.42, and 36.90 nm were formed by employing 190, 300, 400, and 530 nm beads. A solution evaporation method was also utilized to modify PLGA surface features by using 8 wt% (to obtain an AFM RMS value of 0.62 nm) and 4 wt% (to obtain an AFM RMS value of 2.23 nm) PLGA in chloroform solutions. Most importantly, lung cancer epithelial cells adhered less on the PLGA surfaces with RMS values of 0.62, 2.23, and 5.42 nm after four hours of culture compared with any other PLGA surface created here. After three days, PLGA surfaces with an RMS value of 0.62 nm had much lower cell density than any other sample. In this manner, PLGA with specific nanometer surface features may inhibit lung cancer cell density which may provide an important biomaterial for the treatment of lung cancer (from drug delivery to regenerative medicine).

  17. Study of polyacrylamide grafted starch based algal flocculation towards applications in algal biomass harvesting.

    PubMed

    Banerjee, Chiranjib; Gupta, Pratibha; Mishra, Sumit; Sen, Gautam; Shukla, Pratyoosh; Bandopadhyay, Rajib

    2012-11-01

    Microalgae may be the source of high amount of lipid and protein. It has the property for carbon dioxide sequestration, recycling and also can remove pollutants from wastewater. Using traditional methods, collection of algal biomass is either cost effective, time consuming or may be toxic due to use of chemical salts. The aim of this study is to harvest freshwater microalgae (Chlorella sp. CB4) biomass by using polymer. Polyacrylamide grafted starch (St-g-PAM) has been synthesized by microwave assisted method involving a synergism of microwave radiation and ceric ammonium nitrate (CAN) to initiate the grafting reaction. The synthesis was optimized in terms of CAN and monomer (acrylamide) concentration. The algal flocculation efficacy of all the grades of this graft copolymer was studied through standard 'Jar test' procedure. Effects of percentage grafting, pH and zeta potential on percentage recovery of algal biomass were thoroughly investigated.

  18. Algal taxonomy: a road to nowhere?

    PubMed

    De Clerck, Olivier; Guiry, Michael D; Leliaert, Frederik; Samyn, Yves; Verbruggen, Heroen

    2013-04-01

    The widespread view of taxonomy as an essentially retrogressive and outmoded science unable to cope with the current biodiversity crisis stimulated us to analyze the current status of cataloguing global algal diversity. Contrary to this largely pessimistic belief, species description rates of algae through time and trends in the number of active taxonomists, as revealed by the web resource AlgaeBase, show a much more positive picture. More species than ever before are being described by a large community of algal taxonomists. The lack of any decline in the rate at which new species and genera are described, however, is indicative of the large proportion of undiscovered diversity and bears heavily on any prediction of global algal species diversity and the time needed to catalogue it. The saturation of accumulation curves of higher taxa (family, order, and classes) on the other hand suggest that at these taxonomic levels most diversity has been discovered. This reasonably positive picture does not imply that algal taxonomy does not face serious challenges in the near future. The observed levels of cryptic diversity in algae, combined with the shift in methods used to characterize them, have resulted in a rampant uncertainty about the status of many older species. As a consequence, there is a tendency in phycology to move gradually away from traditional names to a more informal system whereby clade-, specimen- or strain-based identifiers are used to communicate biological information. Whether these informal names for species-level clades represent a temporary situation stimulated by the lag between species discovery and formal description, or an incipient alternative or parallel taxonomy, will be largely determined by how well we manage to integrate historical collections into modern taxonomic research. Additionally, there is a pressing need for a consensus about the organizational framework to manage the information about algal species names. An eventual strategy

  19. Different utilization of alginate and other algal polysaccharides by marine Alteromonas macleodii ecotypes.

    PubMed

    Neumann, Anna M; Balmonte, John P; Berger, Martine; Giebel, Helge-Ansgar; Arnosti, Carol; Voget, Sonja; Simon, Meinhard; Brinkhoff, Thorsten; Wietz, Matthias

    2015-10-01

    The marine bacterium Alteromonas macleodii is a copiotrophic r-strategist, but little is known about its potential to degrade polysaccharides. Here, we studied the degradation of alginate and other algal polysaccharides by A. macleodii strain 83-1 in comparison to other A. macleodii strains. Cell densities of strain 83-1 with alginate as sole carbon source were comparable to those with glucose, but the exponential phase was delayed. The genome of 83-1 was found to harbour an alginolytic system comprising five alginate lyases, whose expression was induced by alginate. The alginolytic system contains additional CAZymes, including two TonB-dependent receptors, and is part of a 24 kb genomic island unique to the A. macleodii 'surface clade' ecotype. In contrast, strains of the 'deep clade' ecotype contain only a single alginate lyase in a separate 7 kb island. This difference was reflected in an eightfold greater efficiency of surface clade strains to grow on alginate. Strain 83-1 furthermore hydrolysed laminarin, pullulan and xylan, and corresponding polysaccharide utilization loci were detected in the genome. Alteromonas macleodii alginate lyases were predominantly detected in Atlantic Ocean metagenomes. The demonstrated hydrolytic capacities are likely of ecological relevance and represent another level of adaptation among A. macleodii ecotypes.

  20. The effect of RGD density on osteoblast and endothelial cell behavior on RGD-grafted polyethylene terephthalate surfaces.

    PubMed

    Chollet, Celine; Chanseau, Christel; Remy, Murielle; Guignandon, Alain; Bareille, Reine; Labrugère, Christine; Bordenave, Laurence; Durrieu, Marie-C

    2009-02-01

    Hybrid materials combining polyethylene terephthalate and different types of cells (endothelial and osteoblastic cells) have been developed thanks to the covalent grafting of different densities of RGD containing peptides onto the polymer surface. Biomimetic modifications were performed by means of a three-step reaction procedure: creation of COOH functions, coupling agent grafting and the immobilization of the RGDC peptides. High resolution mu-imager was used to evaluate RGD densities (varying between 0.6 and 2.4 pmol/mm(2)) and has exhibited the stability of the surface grafted peptides when treated in harsh conditions. The efficiency of this route for biomimetic modification of a PET surface was demonstrated by measuring the adhesion of MC3T3 and HSVEC cells and by focal adhesion observation. Results obtained prove that a minimal RGDC density of 1 pmol/mm(2) is required to improve MC3T3 and HSVEC cells responses. Indeed, cells seeded onto a RGDC-modified PET with a density higher than 1 pmol/mm(2) were able to establish focal adhesion as visualized by fluorescence microscope compared to cells immobilized onto unmodified PET and RGDC-modified PET with densities lower than 1 pmol/mm(2). Moreover, the number of focal contacts was enhanced by the increase of RGDC peptide densities grafted onto the material surface. With this study we proved that the density of peptides immobilized on the surface is a very important parameter influencing osteoblast or endothelial cell adhesion and focal contact formation.

  1. Minimally modified low density lipoprotein induces monocyte chemotactic protein 1 in human endothelial cells and smooth muscle cells

    SciTech Connect

    Cushing, S.D.; Berliner, J.A.; Valente, A.J.; Territo, M.C.; Navab, M.; Parhami, F.; Gerrity, R.; Schwartz, C.J.; Fogelman, A.M.

    1990-07-01

    After exposure to low density lipoprotein (LDL) that had been minimally modified by oxidation (MM-LDL), human endothelial cells (EC) and smooth muscle cells (SMC) cultured separately or together produced 2- to 3-fold more monocyte chemotactic activity than did control cells or cells exposed to freshly isolated LDL. This increase in monocyte chemotactic activity was paralleled by increases in mRNA levels for a monocyte chemotactic protein 1 (MCP-1) that is constitutively produced by the human glioma U-105MG cell line. Antibody that had been prepared against cultured baboon smooth muscle cell chemotactic factor (anti-SMCF) did not inhibit monocyte migration induced by the potent bacterial chemotactic factor f-Met-Leu-Phe. However, anti-SMCF completely inhibited the monocyte chemotactic activity found in the media of U-105MG cells, EC, and SMC before and after exposure to MM-LDL. Moreover, monocyte migration into the subendothelial space of a coculture of EC and SMC that had been exposed to MM-LDL was completely inhibited by anti-SMCF. Anti-SMCF specifically immunoprecipitated 10-kDa and 12.5-kDa proteins from EC. Incorporation of (35S)methionine into the immunoprecipitated proteins paralleled the monocyte chemotactic activity found in the medium of MM-LDL stimulated EC and the levels of MCP-1 mRNA found in the EC. We conclude that SMCF is in fact MCP-1 and MCP-1 is induced by MM-LDL.

  2. Process for selection of oxygen-tolerant algal mutants that produce H{sub 2}

    DOEpatents

    Ghirardi, M.L.; Seibert, M.

    1999-02-16

    A process for selection of oxygen-tolerant, H{sub 2}-producing algal mutant cells comprises: (a) growing algal cells photoautotrophically under fluorescent light to mid log phase; (b) inducing algal cells grown photoautotrophically under fluorescent light to mid log phase in step (a) anaerobically by (1) resuspending the cells in a buffer solution and making said suspension anaerobic with an inert gas and (2) incubating the suspension in the absence of light at ambient temperature; (c) treating the cells from step (b) with metronidazole, sodium azide, and added oxygen to controlled concentrations in the presence of white light; (d) washing off metronidazole and sodium azide to obtain final cell suspension; (e) plating said final cell suspension on a minimal medium and incubating in light at a temperature sufficient to enable colonies to appear; (f) counting the number of colonies to determine the percent of mutant survivors; and (g) testing survivors to identify oxygen-tolerant H{sub 2}-producing mutants. 5 figs.

  3. Non-invasive optoacoustic probing of the density and stiffness of single biological cells

    NASA Astrophysics Data System (ADS)

    Dehoux, T.; Audoin, B.

    2012-12-01

    Recently, the coherent generation of GHz acoustic waves using ultrashort laser pulses has demonstrated the ability to probe the sound velocity in vegetal cells and in cell-mimicking soft micro-objects with micrometer resolution, opening tremendous potentialities for single-cell biology. However, manipulating biological media in physiological conditions is often a technical challenge when using a laser-based setup. In this article, we present a new opto-acoustic bio-transducer composed of a thin metal film sputtered on a transparent heat sink that allows reducing importantly the laser-induced cellular stresses, and offers a wide variety of optical configurations. In particular, by exploiting the acoustic reflection coefficient at the sample-transducer interface and the photoacoustic interaction inside the transparent sample, the density and compressibility of the sample can be probed simultaneously. Using an ad hoc signal analysis based on Hilbert and wavelet transforms, these quantities are measured accurately for a reference fluid. Similar analysis performed in a single vegetal cell also suggests high sensitivity to the state of the transducer-cell interface, and notably to the presence of the plasma membrane that encloses the cell vacuole.

  4. High-Density Cell Systems Incorporating Polymer Microspheres as Microenvironmental Regulators in Engineered Cartilage Tissues

    PubMed Central

    Solorio, Loran D.; Vieregge, Eran L.; Dhami, Chirag D.

    2013-01-01

    To address the significant clinical need for tissue-engineered therapies for the repair and regeneration of articular cartilage, many systems have recently been developed using bioactive polymer microspheres as regulators of the chondrogenic microenvironment within high-density cell cultures. In this review, we highlight various densely cellular systems utilizing polymer microspheres as three-dimensional (3D) structural elements within developing engineered cartilage tissue, carriers for cell expansion and delivery, vehicles for spatiotemporally controlled growth factor delivery, and directors of cell behavior via regulation of cell–biomaterial interactions. The diverse systems described herein represent a shift from the more traditional tissue engineering approach of combining cells and growth factors within a biomaterial scaffold, to the design of modular systems that rely on the assembly of cells and bioactive polymer microspheres as building blocks to guide the creation of articular cartilage. Cell-based assembly of 3D microsphere-incorporated structures represents a promising avenue for the future of tissue engineering. PMID:23126333

  5. The relationship of fibroblast translocations to cell morphology and stress fibre density.

    PubMed

    Lewis, L; Verna, J M; Levinstone, D; Sher, S; Marek, L; Bell, E

    1982-02-01

    Translocation of human fibroblasts in culture was studied using techniques of time-lapse cinemicrography, indirect immunofluorescence, and computer analysis. An inverse relationship between the velocity of cells during the last hour of life and the density of stress fibers seen by immune staining was demonstrated. Translocating cells generally assumed one of two interconvertible morphologies: a triangular tailed shape or tailed fibroblast (TF), and a tailless form that resembled a half-moon, which we call a half-moon fibroblast (HMF). The tail of TFs formed only on regions of substrate that had been previously traversed by cells. The half-moon morphology developed either on previously used or on virgin substrate. Cells adopted the HMF rather than the TF morphology with a four-fold greater frequency. HMFs translocated slightly faster than TFs. The foregoing observation suggest that the fibroblast tail is not an organelle essential for translocation. Since our technique allowed us to distinguish between cells which were cycling and those which had left cycle, we compared their velocities and found them to be similar. Also the average velocities of cells of different population-doubling levels (10th, 30th, 40th) were approximately equal.

  6. Lipopolysaccharide enhances oxidative modification of low density lipoprotein by copper ions, endothelial and smooth muscle cells.

    PubMed

    Maziere, C; Conte, M A; Dantin, F; Maziere, J C

    1999-03-01

    The effect of lipopolysaccharide (LPS, endotoxin) on low density lipoprotein (LDL) oxidative modification by copper ions, endothelial and smooth muscle cells was studied by determination of the level of lipid peroxidation products (thiobarbituric acid reactive substances or TBARS), the diene level and the electrophoretic mobility of the LDL particle. LPS 25-75 microg/ml induced a dose-dependent increase in LDL oxidation by copper ions, endothelial and smooth muscle cells. At 75 microg LPS/ml, the TBARS content was 1.9, 1.6, and 1.8-fold increased, respectively. The LDL degradation by J774 macrophage-like cells was concomitantly stimulated. Preincubation of the LDL particle with LPS induced a marked increase in the subsequent LDL oxidative modification either by copper ions or by endothelial and smooth muscle cells. In addition, pretreatment of endothelial and smooth muscle cells with LPS also induced an enhancement of LDL oxidative modification performed in the absence of LPS. This effect was accompanied by a parallel increase in superoxide anion release by the cells. These results point at one of the mechanisms involved in the described association between bacterial infection and acute myocardial infarction as well as coronary heart disease.

  7. Modeling quorum sensing trade-offs between bacterial cell density and system extension from open boundaries.

    PubMed

    Marenda, Mattia; Zanardo, Marina; Trovato, Antonio; Seno, Flavio; Squartini, Andrea

    2016-12-14

    Bacterial communities undergo collective behavioural switches upon producing and sensing diffusible signal molecules; a mechanism referred to as Quorum Sensing (QS). Exemplarily, biofilm organic matrices are built concertedly by bacteria in several environments. QS scope in bacterial ecology has been debated for over 20 years. Different perspectives counterpose the role of density reporter for populations to that of local environment diffusivity probe for individual cells. Here we devise a model system where tubes of different heights contain matrix-embedded producers and sensors. These tubes allow non-limiting signal diffusion from one open end, thereby showing that population spatial extension away from an open boundary can be a main critical factor in QS. Experimental data, successfully recapitulated by a comprehensive mathematical model, demonstrate how tube height can overtake the role of producer density in triggering sensor activation. The biotic degradation of the signal is found to play a major role and to be species-specific and entirely feedback-independent.

  8. Modeling quorum sensing trade-offs between bacterial cell density and system extension from open boundaries

    NASA Astrophysics Data System (ADS)

    Marenda, Mattia; Zanardo, Marina; Trovato, Antonio; Seno, Flavio; Squartini, Andrea

    2016-12-01

    Bacterial communities undergo collective behavioural switches upon producing and sensing diffusible signal molecules; a mechanism referred to as Quorum Sensing (QS). Exemplarily, biofilm organic matrices are built concertedly by bacteria in several environments. QS scope in bacterial ecology has been debated for over 20 years. Different perspectives counterpose the role of density reporter for populations to that of local environment diffusivity probe for individual cells. Here we devise a model system where tubes of different heights contain matrix-embedded producers and sensors. These tubes allow non-limiting signal diffusion from one open end, thereby showing that population spatial extension away from an open boundary can be a main critical factor in QS. Experimental data, successfully recapitulated by a comprehensive mathematical model, demonstrate how tube height can overtake the role of producer density in triggering sensor activation. The biotic degradation of the signal is found to play a major role and to be species-specific and entirely feedback-independent.

  9. Absolute Density Calibration Cell for Laser Induced Fluorescence Erosion Rate Measurements

    NASA Technical Reports Server (NTRS)

    Domonkos, Matthew T.; Stevens, Richard E.

    2001-01-01

    Flight qualification of ion thrusters typically requires testing on the order of 10,000 hours. Extensive knowledge of wear mechanisms and rates is necessary to establish design confidence prior to long duration tests. Consequently, real-time erosion rate measurements offer the potential both to reduce development costs and to enhance knowledge of the dependency of component wear on operating conditions. Several previous studies have used laser-induced fluorescence (LIF) to measure real-time, in situ erosion rates of ion thruster accelerator grids. Those studies provided only relative measurements of the erosion rate. In the present investigation, a molybdenum tube was resistively heated such that the evaporation rate yielded densities within the tube on the order of those expected from accelerator grid erosion. This work examines the suitability of the density cell as an absolute calibration source for LIF measurements, and the intrinsic error was evaluated.

  10. Bidirectional flux of cholesterol between cells and lipoproteins. Effects of phospholipid depletion of high density lipoprotein

    SciTech Connect

    Johnson, W.J.; Bamberger, M.J.; Latta, R.A.; Rapp, P.E.; Phillips, M.C.; Rothblat, G.H.

    1986-05-05

    The bidirectional surface transfer of free cholesterol (FC) between Fu5AH rat hepatoma cells and human high density lipoprotein (HDL) was studied. Cells and HDL were prelabeled with (4-/sup 14/C)FC and (7-/sup 3/H)FC, respectively. Influx and efflux of FC were measured simultaneously from the appearance of /sup 3/H counts in cells and /sup 14/C counts in medium. Results were analyzed by a computerized procedure which fitted sets of kinetic data to a model assuming that cell and HDL FC populations each formed a single homogeneous pool and that together the pools formed a closed system. This analysis yielded values for the first-order rate constants of FC influx and efflux (ki and ke), from which influx and efflux of FC mass (Fi and Fe) could be calculated. With normal HDL, the uptake and release of FC tracers conformed well to the above-described model; Fi and Fe were approximately equal, suggesting an exchange of FC between cells and HDL. HDL was depleted of phospholipid (PL) by treatment with either phospholipase A2 or heparin-releasable rat hepatic lipase, followed by incubation with bovine serum albumin. PL depletion of HDL had little or no effect on ki, but reduced ke, indicating that PL-deficient HDL is a relatively poor acceptor of cell cholesterol. The reduction in ke resulted in initial Fi greater than Fe and, thus, in net uptake of FC by the cells. This result explained previous results demonstrating net uptake of FC from PL-depleted HDL. In the presence of an inhibitor of acyl coenzyme A:cholesterol acyltransferase, the steady state distribution of FC mass between cells and HDL was accurately predicted by the ratio of rate constants for FC flux. This result provided additional validation for describing FC flux in terms of first-order rate constants and homogeneous cell and HDL FC pools.

  11. Effects of algal turfs and sediment on coral settlement.

    PubMed

    Birrell, Chico L; McCook, Laurence J; Willis, Bette L

    2005-01-01

    Successful settlement and recruitment of corals is critical to the resilience of coral reefs. Given that many degraded reefs are dominated by benthic algae, recovery of coral populations after bleaching and other disturbances requires successful settlement amidst benthic algae. Algal turfs often accumulate sediments, sediments are known to inhibit coral settlement, and reefs with high inputs of terrestrial sediments are often dominated by turfs. We investigated the impacts of two algal turf assemblages, and of sediment deposits, on settlement of the coral Acropora millepora (Ehrenberg). Adding sediment reduced coral settlement, but the effects of different algal turfs varied. In one case, algal turfs inhibited coral settlement, whereas the other turf only inhibited settlement when combined with sediments. These results provide the first direct, experimental evidence of effects of filamentous algal turfs on coral settlement, the variability in those effects, and the potential combined effects of algal turfs and trapped sediments.

  12. Wastewater treatment high rate algal ponds for biofuel production.

    PubMed

    Park, J B K; Craggs, R J; Shilton, A N

    2011-01-01

    While research and development of algal biofuels are currently receiving much interest and funding, they are still not commercially viable at today's fossil fuel prices. However, a niche opportunity may exist where algae are grown as a by-product of high rate algal ponds (HRAPs) operated for wastewater treatment. In addition to significantly better economics, algal biofuel production from wastewater treatment HRAPs has a much smaller environmental footprint compared to commercial algal production HRAPs which consume freshwater and fertilisers. In this paper the critical parameters that limit algal cultivation, production and harvest are reviewed and practical options that may enhance the net harvestable algal production from wastewater treatment HRAPs including CO(2) addition, species control, control of grazers and parasites and bioflocculation are discussed.

  13. Cell membrane damage is involved in the impaired survival of bone marrow stem cells by oxidized low-density lipoprotein.

    PubMed

    Li, Xin; Xiao, Yuan; Cui, Yuqi; Tan, Tao; Narasimhulu, Chandrakala A; Hao, Hong; Liu, Lingjuan; Zhang, Jia; He, Guanglong; Verfaillie, Catherine M; Lei, Minxiang; Parthasarathy, Sampath; Ma, Jianjie; Zhu, Hua; Liu, Zhenguo

    2014-12-01

    Cell therapy with bone marrow stem cells (BMSCs) remains a viable option for tissue repair and regeneration. A major challenge for cell therapy is the limited cell survival after implantation. This study was to investigate the effect of oxidized low-density lipoprotein (ox-LDL, naturally present in human blood) on BMSC injury and the effect of MG53, a tissue repair protein, for the improvement of stem cell survival. Rat bone marrow multipotent adult progenitor cells (MAPCs) were treated with ox-LDL, which caused significant cell death as reflected by the increased LDH release to the media. Exposure of MAPCs to ox-LDL led to entry of fluorescent dye FM1-43 measured under confocal microscope, suggesting damage to the plasma membrane. Ox-LDL also generated reactive oxygen species (ROS) as measured with electron paramagnetic resonance spectroscopy. While antioxidant N-acetylcysteine completely blocked ROS production from ox-LDL, it failed to prevent ox-LDL-induced cell death. When MAPCs were treated with the recombinant human MG53 protein (rhMG53) ox-LDL induced LDH release and FM1-43 dye entry were significantly reduced. In the presence of rhMG53, the MAPCs showed enhanced cell survival and proliferation. Our data suggest that membrane damage induced by ox-LDL contributed to the impaired survival of MAPCs. rhMG53 treatment protected MAPCs against membrane damage and enhanced their survival which might represent a novel means for improving efficacy for stem cell-based therapy for treatment of diseases, especially in setting of hyperlipidemia.

  14. Proterozoic microfossils revealing the time of algal divergences

    NASA Astrophysics Data System (ADS)

    Moczydlowska-Vidal, Malgorzata

    2010-05-01

    Proterozoic microfossils revealing the time of algal divergences Małgorzata Moczydłowska-Vidal Uppsala University, Department of Earth Sciences, Palaeobiology, Villavägen 16, SE 752 36 Uppsala, Sweden (malgo.vidal@pal.uu.se) Morphological and reproductive features and cell wall ultrastructure and biochemistry of Proterozoic acritarchs are used to determine their affinity to modern algae. The first appearance datum of these microbiota is traced to infer a minimum age of the divergence of the algal classes to which they may belong. The chronological appearance of microfossils that represent phycoma-like and zygotic cysts and vegetative cells and/or aplanospores, respectively interpreted as prasinophyceaen and chlorophyceaen microalgae, is related to the Viridiplantae phylogeny. These divergence times differ from molecular clock estimates, and the palaeontological evidence suggests that they are older. The best examples of unicellular, organic-walled microfossils (acritarchs) from the Mesoproterozoic to Early Ordovician are reviewed to demonstrate features, which are indicative of their affinity to photosynthetic microalgae. The first indication that a microfossil may be algal is a decay- and acid-resistant cell wall, which reflects its biochemistry and ultrastructure, and probably indicates the ability to protect a resting/reproductive cyst. The biopolymers synthesized in the cell walls of algae and in land plants ("plant cells"), such as sporopollenin/algaenan, are diagnostic for photosynthetic taxa and were inherited from early unicellular ancestors. These preservable cell walls are resistant to acetolysis, hydrolysis and acids, and show diagnostic ultrastructures such as the trilaminar sheath structure (TLS). "Plant cell" walls differ in terms of chemical compounds, which give high preservation potential, from fungal and animal cell walls. Fungal and animal cells are fossilized only by syngenetic permineralization, whereas "plant cells" are fossilized as body

  15. Iron-based cathode catalyst with enhanced power density in polymer electrolyte membrane fuel cells.

    PubMed

    Proietti, Eric; Jaouen, Frédéric; Lefèvre, Michel; Larouche, Nicholas; Tian, Juan; Herranz, Juan; Dodelet, Jean-Pol

    2011-08-02

    H(2)-air polymer-electrolyte-membrane fuel cells are electrochemical power generators with potential vehicle propulsion applications. To help reduce their cost and encourage widespread use, research has focused on replacing the expensive Pt-based electrocatalysts in polymer-electrolyte-membrane fuel cells with a lower-cost alternative. Fe-based cathode catalysts are promising contenders, but their power density has been low compared with Pt-based cathodes, largely due to poor mass-transport properties. Here we report an iron-acetate/phenanthroline/zeolitic-imidazolate-framework-derived electrocatalyst with increased volumetric activity and enhanced mass-transport properties. The zeolitic-imidazolate-framework serves as a microporous host for phenanthroline and ferrous acetate to form a catalyst precursor that is subsequently heat treated. A cathode made with the best electrocatalyst from this work, tested in H(2)-O(2,) has a power density of 0.75 W cm(-2) at 0.6 V, a meaningful voltage for polymer-electrolyte-membrane fuel cells operation, comparable with that of a commercial Pt-based cathode tested under identical conditions.

  16. Optimization of the cell seeding density and modeling of cell growth and metabolism using the modified Gompertz model for microencapsulated animal cell culture.

    PubMed

    Wen-tao, Qi; Ying, Zhang; Juan, Ma; Xin, Guo; Yu-bing, Xie; Wei, Wang; Xiaojun, Ma

    2006-04-05

    Cell microencapsulation is one of the promising strategies for the in vitro production of proteins or in vivo delivery of therapeutic products. In order to design and fabricate the optimized microencapsulated cell system, the Gompertz model was applied and modified to describe the growth and metabolism of microencapsulated cell, including substrate consumption and product formation. The Gompertz model successfully described the cell growth kinetics and the modified Gompertz models fitted the substrate consumption and product formation well. It was demonstrated that the optimal initial cell seeding density was about 4-5 x 10(6) cells/mL of microcapsule, in terms of the maximum specific growth rate, the glucose consumption potential and the product formation potential calculated by the Gompertz and modified Gompertz models. Modeling of cell growth and metabolism in microcapsules provides a guideline for optimizing the culture of microencapsulated cells.

  17. Isolation and characterization of mesenchymal stem cells from the fat layer on the density gradient separated bone marrow.

    PubMed

    Insausti, Carmen L; Blanquer, Miguel Blanquer; Olmo, Luis Meseguer; López-Martínez, María C; Ruiz, Xavier Férez; Lozano, Francisco J Rodríguez; Perianes, Valentín Cabañas; Funes, Consuelo; Nicolás, Francisco J; Majado, María J; Jiménez, José M Moraleda

    2012-01-20

    The density gradient centrifugation method was originally designed for the isolation of mononuclear peripheral blood cells and rapidly adapted to fractionate bone marrow (BM) cells. This method involves the use of gradient density solutions with low viscosity and low osmotic pressure that allows erythrocytes and more mature cells gravitate to the bottom at a density fraction superior to 1.080 g/dL; mononuclear cells (MNCs) held in the plasma-solution to interphase at a density between 1.053 and 1.073 g/dL; plasma, dilution medium and anticoagulant to occupy a density less than 1.050 g/dL and the fat cells to float due to their very low density. BM-mesenchymal stem cells (MSCs) are usually obtained after the separation and cultures of BM-MNCs from the plasma-solution interphase, which is traditionally considered the only source of progenitor cells (hematopoietic and nonhematopoietic). In this study evidences that MSCs could be isolated from the very low-density cells of the fat layer are presented. In addition, we demonstrated that the MSCs obtained from these cells have similar immunophenotypic characteristics, and similar proliferative and differentiation potential to those obtained from the MNCs at plasma-solution interphase. The method represents a simple and cost effective way to increase the MSCs yield from each BM donor, without the need to look for other sources, additional manipulation of cells, and risks of contamination or disturbances of the potential of differentiation. These cells might serve as a complementary source of MSCs to facilitate preclinical and clinical application in tissue engineering and cell therapy.

  18. The Impact of Harmful Algal Blooms on USACE Operations

    DTIC Science & Technology

    2009-01-01

    algae multiply rapidly and accumulate in large numbers, creating an event referred to as an algal bloom. Algal blooms have occurred throughout... algae for their color (Woods Hole Oceanographic Institute 2008; Vézie et al. 1998, 2002). Algal blooms can prove harmful through reductions in...when algae species produce toxins such as microcystin, saxitoxin, brevetoxin, ciguatoxin, or domoic acid (Van Dolah 2000). There is still much to be

  19. Overexpression of LOXIN Protects Endothelial Progenitor Cells From Apoptosis Induced by Oxidized Low Density Lipoprotein.

    PubMed

    Veas, Carlos; Jara, Casandra; Willis, Naomi D; Pérez-Contreras, Karen; Gutierrez, Nicolas; Toledo, Jorge; Fernandez, Paulina; Radojkovic, Claudia; Zuñiga, Felipe A; Escudero, Carlos; Aguayo, Claudio

    2016-04-01

    Human endothelial progenitor cells (hEPC) are adult stem cells located in the bone marrow and peripheral blood. Studies have indicated that hEPC play an important role in the recovery and repair of injured endothelium, however, their quantity and functional capacity is reduced in several diseases including hypercholesterolemia. Recently, it has been demonstrated that hEPC express lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and its activation by oxidized low-density lipoprotein (ox-LDL) induces cellular dysfunction and apoptosis. This study aimed to investigate whether overexpression of LOXIN, a truncated isoform of LOX-1 that acts as a dominant negative, plays a protective role against ox-LDL-induced apoptosis in hEPC. Human endothelial progenitor cells exposed to ox-LDL showed a significant increase in LOX-1 expression, and apoptosis began at ox-LDL concentrations above 50 μg/mL. All hEPC apoptosed at 200 μg/mL ox-LDL. High LOXIN expression was generated using adenoviral systems in hEPC and SiHa cells transduced with 100 colony-forming units per cell. Transduced LOXIN localized to the plasma membrane and blocked ox-LDL uptake mediated by LOX-1. Overexpression of LOXIN protected hEPC from ox-LDL-induced apoptosis, and therefore maybe a novel way of improving hEPC function and quantity. These results suggest that adenoviral vectors of LOXIN may provide a possible treatment for diseases related to ox-LDL and vascular endothelium dysfunction, including atherosclerosis.

  20. Improving accuracy of cell and chromophore concentration measurements using optical density

    PubMed Central

    2013-01-01

    Background UV–vis spectrophotometric optical density (OD) is the most commonly-used technique for estimating chromophore formation and cell concentration in liquid culture. OD wavelength is often chosen with little thought given to its effect on the quality of the measurement. Analysis of the contributions of absorption and scattering to the measured optical density provides a basis for understanding variability among spectrophotometers and enables a quantitative evaluation of the applicability of the Beer-Lambert law. This provides a rational approach for improving the accuracy of OD measurements used as a proxy for direct dry weight (DW), cell count, and pigment levels. Results For pigmented organisms, the choice of OD wavelength presents a tradeoff between the robustness and the sensitivity of the measurement. The OD at a robust wavelength is primarily the result of light scattering and does not vary with culture conditions; whereas, the OD at a sensitive wavelength is additionally dependent on light absorption by the organism’s pigments. Suitably robust and sensitive wavelengths are identified for a wide range of organisms by comparing their spectra to the true absorption spectra of dyes. The relative scattering contribution can be reduced either by measurement at higher OD, or by the addition of bovine serum albumin. Reduction of scattering or correlation with off-peak light attenuation provides for more accurate assessment of chromophore levels within cells. Conversion factors between DW, OD, and colony-forming unit density are tabulated for 17 diverse organisms to illustrate the scope of variability of these correlations. Finally, an inexpensive short pathlength LED-based flow cell is demonstrated for the online monitoring of growth in a bioreactor at culture concentrations greater than 5 grams dry weight per liter which would otherwise require off-line dilutions to obtain non-saturated OD measurements. Conclusions OD is most accurate as a time

  1. Monitoring of ocean surface algal blooms in coastal and oceanic waters around India.

    PubMed

    Tholkapiyan, Muniyandi; Shanmugam, Palanisamy; Suresh, T

    2014-07-01

    (GBEF) system, which increases supply of nutrients in addition to the land-derived inputs triggering surface algal blooms in this region. Low density (initiation stage) of such blooms observed in clear oceanic waters southeast and northeast of Sri Lanka may be caused by the vertical mixing processes (strong monsoonal winds) and the occurrence of Indian Ocean Dipole events. Findings based on the analyses of time series satellite data indicate that the new information on surface algal blooms will have important bearing on regional fisheries, ecosystem and environmental studies, and implications of climate change scenarios.

  2. Refractive index enhancement with vanishing absorption in short, high-density vapor cells

    NASA Astrophysics Data System (ADS)

    Simmons, Z. J.; Proite, N. A.; Miles, J.; Sikes, D. E.; Yavuz, D. D.

    2012-05-01

    It has recently been predicted and experimentally demonstrated that the refractive index of a vapor may be enhanced while maintaining vanishing absorption by using the interference of two Raman transitions, one absorptive and one amplifying in nature. In this paper, we present a detailed experimental study of this technique in a 1-mm-long rubidium (Rb) vapor cell with densities exceeding 1014 cm-3. We study the optimization of the achieved