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Sample records for algal cell density

  1. Role of initial cell density of algal bioassay of toxic chemicals.

    PubMed

    Singh, Prashant Kumar; Shrivastava, Alok Kumar

    2016-07-01

    A variety of toxicants such as, metal ions, pesticides, dyes, etc. are continuously being introduced anthropogenically in the environment and adversely affect to the biotic component of the ecosystem. Therefore, the assessment of negative effects of these toxicants is required. However, toxicity assessment anticipated by chemical analysis are extremely poor, therefore the application of the living systems for the same is an excellent approach. Concentration of toxicant as well as cell density both influenced the result of the algal toxicity assay. Here, Scenedesmus sp, a very fast growing green microalgae was selected for study the effects of initial cell densities on the toxicity of Cu(II), Cd(II), Zn(II), paraquat and 2,4-D. Results demonstrated concentration dependent decrease in biomass and specific growth rate of Scenedesmus sp. on exposure of abovesaid toxicants. Paraquat and 2,4-D emerged as extremely toxic to the test alga which reflected from the lowest EC value and very steep decline in biomass was evident with increasing concentration of paraquat and 2,4-D in the medium. Result also demonstrated that initial cell density is a very important parameter than specific growth rate for algal bioassay of various toxicants. Present study clearly illustrated that the use of smaller cell density is always recommended for assaying toxicity of chemicals in algal assays. PMID:26593761

  2. 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. PMID:22426090

  3. 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. PMID:25435068

  4. 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. PMID:25149444

  5. Stability of alginate-immobilized algal cells

    SciTech Connect

    Dainty, A.L.; Goulding, K.H.; Robinson, P.K.; Simpkins, I; Trevan, M.D.

    1986-01-01

    Investigations were carried out using immobilized Chlorella cells to determine the diameter, compressibility, tolerance to phosphate chelation, and ability to retain algal cells during incubation of various alginate beads. These physical bead-characteristics were affected by a variety of interactive factors, including multivalent cation type (hardening agent) and cell, cation, and alginate concentration, the latter exhibiting a predominant influence. The susceptibility of alginate beads to phosphate chelation involved a complex interaction of cation type, concentration, and pH of phosphate solution. A scale of response ranging from gel swelling to gel shrinking was observed for a range of conditions. However, stable Ca alginate beads were maintained in incubation media with a pH of 5.5 and a phosphate concentration of 5 micro M. A preliminary investigation into cell leakage from the beads illustrated the importance of maintaining a stable gel structure and limiting cell growth to reduce leakage.

  6. Evaluation of High Density Algal Cultivation for Secondary Wastewater Polishing.

    PubMed

    Xu, Meng; Xu, Shengnan; Bernards, Matthew; Hu, Zhiqiang

    2016-01-01

    This study evaluated the performance of an algal membrane bioreactor (A-MBR) for secondary wastewater effluent polishing and determined the membrane fouling behavior and dominance of algae in the A-MBR. The continuous flow A-MBR (effective volume = 7.2 L) was operated with low biomass wastage for more than 180 days, resulting in an average algal mixed liquor suspended solid concentration of 4922 mg/L. At the influent concentrations of 43 mg/L COD, 1.6 mg/L total phosphorus (TP), and 11.8 mg/L total nitrogen (TN), the effluent COD, TP and TN concentrations were 26 ± 6 mg/L, 0.7 ± 0.3 mg/L, and 9.6 ± 1.2 mg/L, respectively. High-density algae cultivation facilitated P adsorption and chemical precipitation. However, the TN removal efficiency was only 14% because of low biomass wastage. Although bacteria represented less than 2% of the total biomass in the A-MBR, bacterial growth in the secondary wastewater effluent accelerated membrane fouling. PMID:26803026

  7. 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.

  8. Effects of algal concentration and initial density on the population growth of Diaphanosoma celebensis Stingelin (Crustacea, Cladocera)

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Xie, Ningxia; Wang, Weiliang

    2009-09-01

    The effects of algal concentration and initial density on the population growth of the estuarine cladocera, Diaphanosoma celebensis Stingelin, were evaluated in an indoor experiment. A 2 × 4 layout that included two algal concentrations ( Chlorella pyrenoidosa, 1 × 106 and 3 × 106 cell/mL) and four inoculation densities (100, 200, 300 and 400 ind./L) were established. Diaphanosoma celebensis were reared in 150 mL flasks containing 50 mL of algal medium at 22°C, under salinity of 10 and a photoperiod of 12 h L: 12 h D. The lag phase required to initiate continuous population growth following inoculation was shorter for D. celebensis fed 1 × 106 cell/mL and inoculated at 300 or 400 ind./L than that for D. celebensis fed 3 × 106 cell/mL and inoculated at 100 or 200 ind./L. However, D. celebensis fed 3 × 106 cell/mL and inoculated at 100 or 200 ind./L exhibited longer periods of positive population growth. The maximum population densities were 5 875 ± 324, 6 690 ± 691, 7 735 ± 1,121 and 6 365 ± 691 ind./L for D. celebensis fed 1 × 106 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively, and 15 070 ± 379, 12 215 ± 648, 11 960 ± 2,551 and 16 130 ± 880 ind./L for D. celebensis fed 3 × 106 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively. The average daily increasing rates of population were 0.076 ± 0.001, 0.065 ± 0.002, 0.055 ± 0.002 and 0.048 ± 0.003 for D. celebensis fed 1×106 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively, and 0.098 ± 0.001, 0.078 ± 0.002, 0.072 ± 0.003 and 0.067 ± 0.003 for D. celebensis fed 3 × 106 cell/mL and inoculated at 100, 200, 300 and 400 ind./L, respectively. The maximum population density and average daily increasing rate of population increased as the algal concentration increased, whereas an increase in the inoculation density led to a linear decrease in the daily increasing rate of population under both algal concentrations. The results of the present

  9. Flagellar waveform analysis of swimming algal cells

    NASA Astrophysics Data System (ADS)

    Kurtuldu, Huseyin; Johnson, Karl; Gollub, Jerry

    2011-11-01

    The twin flagella of the green alga Chlamydomas reinhardtii are driven by dynein molecular motors to oscillate at about 50-60 Hz in a breaststroke motion. For decades, Chlamydomas has been used as a model organism for studies of flagellar motility, and of genetic disorders of ciliary motion. However, little is known experimentally about the flagellar waveforms, and the resulting time-dependent force distribution along the 250 nm diameter flagella. Here, we study flagellar dynamics experimentally by confining cells in quasi-2D liquid films. From simultaneous measurements of the cell body velocity and the time-dependent velocities along the center lines of the two flagella, we determine the drag coefficients, and estimate the power expended by the body and the flagella, comparing our findings with measurements based on the induced fluid flow field. We contrast the results for the quite different beating patterns of synchronous and asynchronous flagella, respectively. Supported by NSF Grant DMR-0803153.

  10. 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.

  11. Plant and algal cell walls: diversity and functionality

    PubMed Central

    Popper, Zoë A.; Ralet, Marie-Christine; Domozych, David S.

    2014-01-01

    Background Although plants and many algae (e.g. the Phaeophyceae, brown, and Rhodophyceae, red) are only very distantly related they are united in their possession of carbohydrate-rich cell walls, which are of integral importance being involved in many physiological processes. Furthermore, wall components have applications within food, fuel, pharmaceuticals, fibres (e.g. for textiles and paper) and building materials and have long been an active topic of research. As shown in the 27 papers in this Special Issue, as the major deposit of photosynthetically fixed carbon, and therefore energy investment, cell walls are of undisputed importance to the organisms that possess them, the photosynthetic eukaryotes (plants and algae). The complexities of cell wall components along with their interactions with the biotic and abiotic environment are becoming increasingly revealed. Scope The importance of plant and algal cell walls and their individual components to the function and survival of the organism, and for a number of industrial applications, are illustrated by the breadth of topics covered in this issue, which includes papers concentrating on various plants and algae, developmental stages, organs, cell wall components, and techniques. Although we acknowledge that there are many alternative ways in which the papers could be categorized (and many would fit within several topics), we have organized them as follows: (1) cell wall biosynthesis and remodelling, (2) cell wall diversity, and (3) application of new technologies to cell walls. Finally, we will consider future directions within plant cell wall research. Expansion of the industrial uses of cell walls and potentially novel uses of cell wall components are both avenues likely to direct future research activities. Fundamentally, it is the continued progression from characterization (structure, metabolism, properties and localization) of individual cell wall components through to defining their roles in almost every

  12. Flocculation of algal cells by amphoteric chitosan-based flocculant.

    PubMed

    Dong, Changlong; Chen, Wei; Liu, Cheng

    2014-10-01

    A kind of amphoteric chitosan-based flocculant (quaternized carboxymethyl chitosan, denoted as QCMC) has been prepared. QCMC presented significant improvement of water solubility in the whole pH range. The effects of pH, dosage, temperature and original turbidity of algal water on the flocculation performance were investigated. The optimal dosages of QCMC at pH 5, 9 and 12 with original turbidity of 20NTU at 20°C were 0.1, 0.6 and 2.0mg/L, respectively, which were much less than that of chitosan, PAM, Al2(SO4)3 and FeCl3. The floc properties during grow, breakage and regrow period were also evaluated at different pH values in terms of floc size, strength and density. It was demonstrated that QCMC produced larger, stronger and denser flocs than Al2(SO4)3. There is every indication that QCMC is more suitable for algal harvesting than other traditional coagulants or flocculants. PMID:25146316

  13. 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.

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

    SciTech Connect

    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.

  15. Effects of four rice paddy herbicides on algal cell viability and the relationship with population recovery.

    PubMed

    Nagai, Takashi; Ishihara, Satoru; Yokoyama, Atsushi; Iwafune, Takashi

    2011-08-01

    Paddy herbicides are a high-risk concern for aquatic plants, including algae, because they easily flow out from paddy fields into rivers, with toxic effects. The effect on algal population dynamics, including population recovery after timed exposure, must be assessed. Therefore, we demonstrated concentration-response relationships of four paddy herbicides for algal growth inhibition and mortality, and the relationship between the effect on algal cell viability and population recovery following exposure. We used SYTOX Green dye assay and flow cytometry to assess cell viability of the alga Pseudokirchneriella subcapitata. Live cells could be clearly distinguished from dead cells during herbicide exposure. Our results showed that pretilachlor and quinoclamine had both algicidal and algistatic effects, whereas bensulfuron-methyl only had an algistatic effect, and pentoxazone only had an algicidal effect. Then, a population recovery test following a 72-h exposure was conducted. The algal population recovered in all tests, but the periods required for recovery differed among exposure concentrations and herbicides. The periods required for recovery were inconsistent with the dead cell ratio at the beginning of the recovery test; that is, population recovery could not be described only by cell viability. Consequently, the temporal effect of herbicides and subsequent recovery of the algal population could be described not only by the toxicity characteristics but also by toxicokinetics, such as rate of uptake, transport to the target site, and elimination of the substance from algal cells. PMID:21590715

  16. Combined effects of algal (Chlorella vulgaris) density and ammonia concentration on the population dynamics of Ceriodaphnia dubia and Moina macrocopa (Cladocera).

    PubMed

    Mangas-Ramírez, Ernesto; Sarma, S S S; Nandini, S

    2002-03-01

    Ammonia is a natural variable in ponds and lakes. Although an important source of nitrogen for microalgae, at high concentrations ammonia can affect the density and diversity of cladocerans. Using the cladocerans Ceriodaphnia dubia, and Moina macrocopa, the effect of nominal concentrations of ammonium chloride under acute and chronic exposures at different levels of algal food was tested. Regardless of food level, C. dubia was more sensitive than M. macrocopa to ammonia. In the absence of food, the median lethal concentration of ammonia (LC(50) 24 h) for C. dubia was (112 mg L(-1)) less than half that of M. macrocopa (232 mg L(-1)). When algal food (0.5 x 10(6) and 1.5 x 10(6) cells ml(-1) of Chlorella) was used, the LC(50) values were much higher for both cladoceran species. Based on the population growth studies, it was found that in controls of M. macrocopa an increase in the availability of Chlorella from 0.5 to 1.5 x 10(6) cells mL(-1) led to an increase in the maximum density from 4.7 +/- 0.2 to 16.4 +/- 1.2 ind.mL(-1), while in C. dubia the peak population density decreased from 7.9 +/- 0.6 to 5.0 +/- l.0 ind.mL(-1). An increase in ammonia concentration (10 to 40 mg L(-1) for C. dubia and 20 to 120 mg L(-1) for M. macrocopa) resulted in a corresponding decrease in peak population densities of the tested cladocerans. The rate of population increase (r) values for M. macrocopa in the controls ranged from 0.21 +/- 0.001 and 0.25 +/- 0.02 at 0.5 and 1.5 x 10(6) cells mL(-1) of Chlorella, respectively. The corresponding values of C. dubia in controls were 0.21 +/- 0.004 and 0.18 +/- 0.01. At 0.5 x 10(6) cells mL(-1) of algal food, the r values became negative under 40 and 120 mg L(-1) of ammonia for C. dubia and M. macrocopa, respectively. The role of algal food in ammonia toxicity to cladocerans was discussed. (c) 2002 Elsevier Science (USA). PMID:11971644

  17. 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. PMID:24057921

  18. Role of gas vesicles and intra-colony spaces during the process of algal bloom formation.

    PubMed

    Zhang, Yongsheng; Zheng, Binghui; Jiang, Xia; Zheng, Hao

    2013-06-01

    Aggregation morphology, vertical distribution, and algal density were analyzed during the algal cell floating process in three environments. The role of gas vesicles and intra-colony spaces was distinguished by algal blooms treated with ultrasonic waves and high pressure. Results demonstrated that the two buoyancy providers jointly provide buoyancy for floating algal cells. The results were also confirmed by force analysis. In the simulation experiment, the buoyancy acting on algal cells was greater than its gravity at sample ports 2 and 3 of a columnar-cultivated cell vessel, and intra-colony spaces were not detected. In Taihu Lake, gas vesicle buoyancy was notably less than total algal cell gravity. Buoyancy provided by intra-colony spaces exceeded total algal cell gravity at the water surface, but not at other water depths. In the Daning River, total buoyancies provided by the two buoyancy providers were less than total algal cell gravity at different water depths. PMID:23833817

  19. A comparative study on the effect of algal and fish oil on viability and cell proliferation of Caco-2 cells.

    PubMed

    van Beelen, Vincent A; Roeleveld, Johannes; Mooibroek, Hans; Sijtsma, Lolke; Bino, Raoul J; Bosch, Dirk; Rietjens, Ivonne M C M; Alink, Gerrit M

    2007-05-01

    Polyunsaturated fatty acid (PUFA) rich micro-algal oil was tested in vitro and compared with fish oil for antiproliferative properties on cancer cells in vitro. Oils derived from Crypthecodinium cohnii, Schizochytrium sp. and Nitzschia laevis, three commercial algal oil capsules, and menhaden fish oil were used in cell viability and proliferation tests with human colon adenocarcinoma Caco-2 cells. With these tests no difference was found between algal oil and fish oil. The nonhydrolysed algal oils and fish oil showed a much lower toxic effect on cell viability, and cell proliferation in Caco-2 cells than the hydrolysed oils and the free fatty acids (FFAs). Eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3) were used as samples for comparison with the tested hydrolysed and nonhydrolysed oils. The hydrolysed samples showed comparative toxicity as the free fatty acids and no difference between algal and fish oil. Oxidative stress was shown to play a role in the antiproliferative properties of EPA and DHA, as alpha-tocopherol could partially reverse the EPA/DHA-induced effects. The results of the present study support a similar mode of action of algal oil and fish oil on cancer cells in vitro, in spite of their different PUFA content. PMID:17141934

  20. 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. PMID:20547055

  1. Influence of the Cell Wall on Intracellular Delivery to Algal Cells by Electroporation and Sonication

    PubMed Central

    Azencott, Harold R.; Peter, Gary F.; Prausnitz, Mark R.

    2007-01-01

    To assess the cell wall’s role as a barrier to intracellular delivery, wild-type Chlamydomonas reinhardtii algal cells and mutant cells lacking a cell wall were exposed to electroporation or sonication. Flow cytometry determined intracellular uptake of calcein and bovine serum albumin (BSA) and loss of cell viability as functions of electroporation transmembrane potential and acoustic energy. Electroporation of wild-type cells increased calcein uptake with increasing transmembrane potential, but delivered much less BSA. Electroporation of wall-deficient cells had similar effects on calcein uptake, but increased BSA uptake as much as 7.5-fold relative to wild-type cells, which indicated that the cell wall was a significant barrier to BSA delivery during electroporation. Sonication of wild-type cells caused calcein and BSA uptake at similar levels. This suggests that the cell wall barrier to BSA delivery can be overcome by sonication. Increased electroporation transmembrane potential or acoustic energy also caused increased loss of cell viability, where wall-deficient cells were especially susceptible to lysis. Overall, we believe this is the first study to compare the effects of electroporation and sonication in a direct fashion in any cell type. Specifically, these findings suggest that electroporation primarily transports molecules across the plasma membrane, because its mechanism is specific to lipid bilayer disruption, whereas sonication transports molecules across both the plasma membrane and cell wall, because it non-specifically disrupts cell-surface barriers. PMID:17602827

  2. 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. PMID:26722810

  3. 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. PMID:24121206

  4. 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.

  5. Algal autolysate medium to label proteins for NMR in mammalian cells.

    PubMed

    Fuccio, Carmelo; Luchinat, Enrico; Barbieri, Letizia; Neri, Sara; Fragai, Marco

    2016-04-01

    In-cell NMR provides structural and functional information on proteins directly inside living cells. At present, the high costs of the labeled media for mammalian cells represent a limiting factor for the development of this methodology. Here we report a protocol to prepare a homemade growth medium from Spirulina platensis autolysate, suitable to express uniformly labeled proteins inside mammalian cells at a reduced cost-per-sample. The human proteins SOD1 and Mia40 were overexpressed in human cells grown in (15)N-enriched S. platensis algal-derived medium, and high quality in-cell NMR spectra were obtained. PMID:27106902

  6. 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

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

    PubMed Central

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

    2014-01-01

    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. PMID:24759542

  8. Direct extraction of photosynthetic electrons from single algal cells by nanoprobing system.

    PubMed

    Ryu, WonHyoung; Bai, Seoung-Jai; Park, Joong Sun; Huang, Zubin; Moseley, Jeffrey; Fabian, Tibor; Fasching, Rainer J; Grossman, Arthur R; Prinz, Fritz B

    2010-04-14

    There are numerous sources of bioenergy that are generated by photosynthetic processes, for example, lipids, alcohols, hydrogen, and polysaccharides. However, generally only a small fraction of solar energy absorbed by photosynthetic organisms is converted to a form of energy that can be readily exploited. To more efficiently use the solar energy harvested by photosynthetic organisms, we evaluated the feasibility of generating bioelectricity by directly extracting electrons from the photosynthetic electron transport chain before they are used to fix CO(2) into sugars and polysaccharides. From a living algal cell, Chlamydomonas reinhardtii, photosynthetic electrons (1.2 pA at 6000 mA/m(2)) were directly extracted without a mediator electron carrier by inserting a nanoelectrode into the algal chloroplast and applying an overvoltage. This result may represent an initial step in generating "high efficiency" bioelectricity by directly harvesting high energy photosynthetic electrons. PMID:20201533

  9. Bioconvection at the scale of individual algal cells

    NASA Astrophysics Data System (ADS)

    Bearon, Rachel

    2004-11-01

    Bioconvection occurs when microorganisms that are denser than the ambient fluid swim on average upwards, generating an overturning instability. Bioconvection may be an important mechanism for vertical and horizontal aggregation of otherwise dispersed populations. In the case of toxic algae, concentration by bioconvection may have direct ecological and human effects. However, it is not known whether conditions that favor bioconvection commonly exist in nature. We quantified in the laboratory the conditions for bioconvection by Heterosigma akashiwo, a highly motile 10 μm alga that forms toxic blooms worldwide. Cells formed extensive convective patterns, when present in concentrations comparable to those found in a natural bloom (100s cells/ml), even within a salinity-stratified water column. We quantified both the μm scale swimming behavior of individual cells in still water, and the trajectories of cells in a descending bioconvective plume at the cm scale. We present a continuous-time Markov model derived from these data that predicts the evolution of cell concentration during bioconvection and compare the model to observed patterns of bioconvection.

  10. Flow cytometric measurement of pollutant stresses on algal cells

    SciTech Connect

    Berglund, D.L.; Eversman, S.

    1988-03-01

    The lichen Usnea fulvoreagens (Raes). Raes. was treated with four pH levels (5.5, 4.5, 3.5, and 2.5) of simulated acid rain (sulfuric acid, nitric acid, and a 1:1 combination of both) and automobile exhaust. The samples were dissociated and analyzed by a Becton-Dickinson FACS 440 flow cytometer. Analyses included measurement of chlorophyll autofluorescence and fluorescence due to uptake of fluorescein diacetate (FDA) and calcofluor white M2R (CFW). Cell parameters measured were esterase activity (FDA), membrane permeability (FDA, CFW), and intracellular pH (FDA). Mean fluorescence intensity from FDA staining and numbers of events were incorporated with autofluorescence information to produce a stress index of relative cell stress. Results indicated that highly stressed samples (lower pH treatments and greater exposure to exhaust) exhibited a low stress index of FDA fluorescence.Au

  11. NMR imaging of heavy metal absorption in alginate, immobilized cells, and kombu algal biosorbents.

    PubMed

    Nestle, N F; Kimmich, R

    1996-09-01

    In this contribution, an NMR imaging study of heavy metal absorption in alginate, immobilized-cell biosorbents, and kombu (Laminaria japonica) algal biomass is presented. This method provides the good possibility of directly monitoring the time evolution of the spatial distribution of the ions in the materials. From these results, we demonstrate that rare earth ions are absorbed with a steep reaction front that can be described very well with a modified shrinking core model, while copper ions are absorbed with a more diffuse front. PMID:18629817

  12. 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.

  13. High energy density electrochemical cell

    NASA Technical Reports Server (NTRS)

    Byrne, J. J.; Williams, D. L.

    1970-01-01

    Primary cell has an anode of lithium, a cathode containing dihaloisocyanuric acid, and a nonaqueous electrolyte comprised of a solution of lithium perchlorate in methyl formate. It produces an energy density of 213 watt hrs/lb and can achieve a high current density.

  14. 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. PMID:26081162

  15. 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.

  16. [Study on the variation of algal activity during the electrochemical oxidation as inactivation method].

    PubMed

    Liang, Wen-Yan; Wang, Ke; Ruan, Ling-Ling; Sui, Li-Li

    2010-06-01

    The paper studied the variation of algal activity during the electrochemical inactivation and the influence factors by the use of TTC-dehydrogenase activity and neutral red staining assays. The treatment reactor was consisted of Ti/RuO2 rod as anode and stainless steel pipe as cathode. The results showed that algal inactivation rate was 45% in cell density after 30 min treatment at 8 mA/cm2. Whereas the decrease of TTC-dehydrogenase activity was 94% and neutral red staining percentage was 100%. The algae after treatment was unable to regrow and it revealed that the algal activity assays can reflect the inactivation effect more correctly than cell density. The electrolytes could influence the inactivation efficiency. The electrolytes of Na2SO4 and NaNO3 had similar effects on algal inactivation and Na2SO4 concentration had small influence on the treatment. However, when the electrolyte contained 0.1 mmol/L NaCl, the algal inactivation was improved obviously with the 87% for TTC-dehydrogenase activity decrease and 82% for neutral red staining ratio. The initial algal concentration also influenced the treatment efficiency. If cell density increased, the inactivation efficiency decreased significantly. All algal cells in samples with cell density of 4.4 x 10(7) cells/L were completely inactivated by the use of natural water as electrolyte within 1 minute. PMID:20698257

  17. Metal toxicity inferred from algal population density, heterotrophic substrate use, and fatty acid profile in a small stream

    SciTech Connect

    Genter, R.B.; Lehman, R.M.

    2000-04-01

    The purpose of this study was to examine relations between metal concentrations in periphyton and the abundance of algal species, heterotrophic use of 95 carbon sources, and phospholipid fatty acids (PLFA) of the periphyton in a small stream spanning a mine in Lemhi County, Idaho, USA. Two upstream two mine, and two downstream sites were examined. Elevated concentrations of As and Cu at the mine sites were associated with communities that were depleted of diatoms and filamentous blue-green algae and characterized by a low-diversity community dominated by a single blue-green alga and patchy populations of the diatom Achnanthidium minutissimum and a filamentous green alga. Carbon source use and PLFA profiles provided a rapid assessment of stream conditions that were consistent with algal taxonomy and with the hypotheses constructed from previous reports on periphyton responses to metal stress.

  18. Comparison of cell rupturing by ozonation and ultrasonication for algal lipid extraction from Chlorella vulgaris.

    PubMed

    Huang, Yuanxing; Hong, Andy; Zhang, Daofang; Li, Liang

    2014-01-01

    Cell disruption is essential for lipid collection from cultivated microalgae. This study examines the performance of ultrasonication (US), conventional bubbling ozonation (CBO), and pressure-assisted ozonation (PAO) as a cell rupturing technique to obtain algal lipid from a freshwater unicellular microalgae Chlorella vulgaris, which was grown in BG11 medium at a temperature of 25 degrees C and illuminated by artificial lighting with light/dark cycle of 12 h/12 h. Changes in total organic carbon, total nitrogen, total phosphorous, and chlorophyll contents in the algae suspension after ozonation and US treatments were measured to evaluate the effectiveness of cell rupture by these techniques. Lipid yields of 21 and 27 g/100 g biomass were obtained using US and PAO, respectively. Lipid yields of about 5 g/100 g biomass were obtained using CBO. In all rupturing treatments, C16 and C18 compounds were found to be predominant accounting for 90% of the fatty acids. Using US for rupturing, fatty acids of C 16:0, C18:1, and C18:2 were predominant, accounting for 76 +/- 4.2% of all the fatty acids. Using CBO and PAO involving ozone, fatty acids of C16:0 and C18:0 were predominant, accounting for 63-94% of the products. The results suggest that saturated fatty acid methyl ester (FAME) products are predominant with oxidative ozonation rupturing while unsaturated FAME products of lower-melting points predominant with physical ultrasonic rupturing means. PAO was an effective cell rupture method for biodiesel production with high lipid yield and more saturated hydrocarbon products. PMID:24645476

  19. A Simple and Rapid Protocol for Measuring Neutral Lipids in Algal Cells Using Fluorescence

    PubMed Central

    Storms, Zachary J.; Cameron, Elliot; de la Hoz Siegler, Hector; McCaffrey, William C.

    2014-01-01

    Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal fermentation processes and screening for new oil-rich strains requires a fast and reliable protocol for determination of intracellular lipid content. Current practices rely largely on gravimetric methods to determine oil content, techniques developed decades ago that are time consuming and require large sample volumes. In this paper, Nile Red, a fluorescent dye that has been used to identify the presence of lipid bodies in numerous types of organisms, is incorporated into a simple, fast, and reliable protocol for measuring the neutral lipid content of Auxenochlorella protothecoides, a green alga. The method uses ethanol, a relatively mild solvent, to permeabilize the cell membrane before staining and a 96 well micro-plate to increase sample capacity during fluorescence intensity measurements. It has been designed with the specific application of monitoring bioprocess performance. Previously dried samples or live samples from a growing culture can be used in the assay. PMID:24961928

  20. A simple and rapid protocol for measuring neutral lipids in algal cells using fluorescence.

    PubMed

    Storms, Zachary J; Cameron, Elliot; de la Hoz Siegler, Hector; McCaffrey, William C

    2014-01-01

    Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal fermentation processes and screening for new oil-rich strains requires a fast and reliable protocol for determination of intracellular lipid content. Current practices rely largely on gravimetric methods to determine oil content, techniques developed decades ago that are time consuming and require large sample volumes. In this paper, Nile Red, a fluorescent dye that has been used to identify the presence of lipid bodies in numerous types of organisms, is incorporated into a simple, fast, and reliable protocol for measuring the neutral lipid content of Auxenochlorella protothecoides, a green alga. The method uses ethanol, a relatively mild solvent, to permeabilize the cell membrane before staining and a 96 well micro-plate to increase sample capacity during fluorescence intensity measurements. It has been designed with the specific application of monitoring bioprocess performance. Previously dried samples or live samples from a growing culture can be used in the assay. PMID:24961928

  1. 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. PMID:26125613

  2. 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. PMID:23720191

  3. 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. PMID:7925267

  4. Buoyant density constancy of Schizosaccharomyces pombe cells

    SciTech Connect

    Kubitschek, H.E.; Ward, R.A.

    1985-06-01

    Buoyant densities of cells from exponentially growing cultures of the fission yeast Schizosaccharomyces pombe 972h/sup -/ with division rates from 0.14 to 0.5 per h were determined by equilibrium centrifugation in Percoll gradients. Buoyant densities were independent of growth rate, with an average value (+/- standard error) of 1.0945 (+/- 0.00037) g/ml. When cells from these cultures were separated by size, mean cell volumes were independent of buoyant density, indicating that buoyant densities also were independent of cell age during the division cycle. These results support the suggestion that most or all kinds of cells that divide by equatorial fission may have similar, evolutionarily conserved mechanisms for regulation of buoyant density.

  5. 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.

  6. 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. PMID:26183805

  7. 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.

  8. 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.

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

    PubMed Central

    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.

    2015-01-01

    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. PMID:25977457

  10. Rescue of heavy metal effects on cell physiology of the algal model system Micrasterias by divalent ions

    PubMed Central

    Volland, Stefanie; Bayer, Elisabeth; Baumgartner, Verena; Andosch, Ancuela; Lütz, Cornelius; Sima, Evelyn; Lütz-Meindl, Ursula

    2014-01-01

    Recent studies have shown that metals such as copper, zinc, aluminum, cadmium, chromium, iron and lead cause severe dose-dependent disturbances in growth, morphogenesis, photosynthetic and respiratory activity as well as on ultrastructure and function of organelles in the algal model system Micrasterias denticulata (Volland et al., 2011, 2012; Andosch et al., 2012). In the present investigation we focus on amelioration of these adverse effects of cadmium, chromium and lead by supplying the cells with different antioxidants and essential micronutrients to obtain insight into metal uptake mechanisms and subcellular metal targets. This seems particularly interesting as Micrasterias is adapted to extremely low-concentrated, oligotrophic conditions in its natural bog environment. The divalent ions of iron, zinc and calcium were able to diminish the effects of the metals cadmium, chromium and lead on Micrasterias. Iron showed most ameliorating effects on cadmium and chromium in short- and long-term treatments and improved cell morphogenesis, ultrastructure, cell division rates and photosynthesis. Analytical transmission electron microscopic (TEM) methods (electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI)) revealed that chromium uptake was decreased when Micrasterias cells were pre-treated with iron, which resulted in no longer detectable intracellular chromium accumulations. Zinc rescued the detrimental effects of chromium on net-photosynthesis, respiration rates and electron transport in PS II. Calcium and gadolinium were able to almost completely compensate the inhibiting effects of lead and cadmium on cell morphogenesis after mitosis, respectively. These results indicate that cadmium is taken up by calcium and iron transporters, whereas chromium appears to enter the algae cells via iron and zinc carriers. It was shown that lead is not taken up into Micrasterias at all but exerts its adverse effects on cell growth by substituting cell

  11. Rescue of heavy metal effects on cell physiology of the algal model system Micrasterias by divalent ions.

    PubMed

    Volland, Stefanie; Bayer, Elisabeth; Baumgartner, Verena; Andosch, Ancuela; Lütz, Cornelius; Sima, Evelyn; Lütz-Meindl, Ursula

    2014-01-15

    Recent studies have shown that metals such as copper, zinc, aluminum, cadmium, chromium, iron and lead cause severe dose-dependent disturbances in growth, morphogenesis, photosynthetic and respiratory activity as well as on ultrastructure and function of organelles in the algal model system Micrasterias denticulata (Volland et al., 2011, 2012; Andosch et al., 2012). In the present investigation we focus on amelioration of these adverse effects of cadmium, chromium and lead by supplying the cells with different antioxidants and essential micronutrients to obtain insight into metal uptake mechanisms and subcellular metal targets. This seems particularly interesting as Micrasterias is adapted to extremely low-concentrated, oligotrophic conditions in its natural bog environment. The divalent ions of iron, zinc and calcium were able to diminish the effects of the metals cadmium, chromium and lead on Micrasterias. Iron showed most ameliorating effects on cadmium and chromium in short- and long-term treatments and improved cell morphogenesis, ultrastructure, cell division rates and photosynthesis. Analytical transmission electron microscopic (TEM) methods (electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI)) revealed that chromium uptake was decreased when Micrasterias cells were pre-treated with iron, which resulted in no longer detectable intracellular chromium accumulations. Zinc rescued the detrimental effects of chromium on net-photosynthesis, respiration rates and electron transport in PS II. Calcium and gadolinium were able to almost completely compensate the inhibiting effects of lead and cadmium on cell morphogenesis after mitosis, respectively. These results indicate that cadmium is taken up by calcium and iron transporters, whereas chromium appears to enter the algae cells via iron and zinc carriers. It was shown that lead is not taken up into Micrasterias at all but exerts its adverse effects on cell growth by substituting cell

  12. Significance of different carbon forms and carbonic anhydrase activity in monitoring and prediction of algal blooms in the urban section of Jialing River, Chongqing, China.

    PubMed

    Nie, Yudong; Zhang, Zhi; Shen, Qian; Gao, Wenjin; Li, Yingfan

    2016-05-18

    The Three Gorges Dam is one of the largest hydroelectric power plants worldwide; its reservoir was preliminarily impounded in 2003 and finally impounded to 175 m in 2012. The impoundment caused some environmental problems, such as algal blooms. Carbonic anhydrase (CA) is an important biocatalyst in the carbon utilization by algae and plays an important role in algal blooms. CA has received considerable attention for its role in red tides in oceans, but less investigation has been focused on its role in algal blooms in fresh water. In this study, the seasonal variation of water quality parameters, different carbon forms, carbonic anhydrase activity (CAA), and the algal cell density of four sampling sites in the urban section of the Jialing River were investigated from November 1, 2013 to October 31, 2014. Results indicated that CAA exhibited a positive correlation with dissoluble organic carbon (DOC), pH, and temperature, but a negative correlation with CO2 and dissoluble inorganic carbon (DIC). Algal cell density exhibited a positive correlation with flow velocity (V), pH, particulate organic carbon (POC), and CAA, a negative correlation with CO2, and a negative partial correlation with DIC. The relationship between CAA and algal cell density for the entire year can be described as cells = 23.278CAA - 42.666POC + 139.547pH - 1057.106. The algal bloom prediction model for the key control period can be described as cells = -45.895CAA + 776.103V- 29.523DOC + 14.219PIC + 35.060POC + 19.181 (2 weeks in advance) and cells = 69.200CAA + 203.213V + 4.184CO2 + 38.911DOC + 40.770POC - 189.567 (4 weeks in advance). The findings in this study demonstrate that the carbon utilization by algae is conducted by CA and provide a new method of monitoring algal cell density and predicting algal blooms. PMID:27142237

  13. 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.

  14. Limbal Basal Cell Density Decreases in Limbal Stem Cell Deficiency

    PubMed Central

    Chan, Eric H; Chen, Luxia; Rao, Jian Yu; Yu, Fei; Deng, Sophie X.

    2016-01-01

    Purpose To investigate changes in limbal basal epithelial cell density in eyes with limbal stem cell deficiency (LSCD) using in vivo confocal laser scanning microscopy Design retrospective observational comparative study Methods A total of 43 eyes of 30 patients diagnosed with LSCD were included in the study. Ten eyes from normal subjects were included as control. Confocal imaging of the central cornea, and the superior, nasal, inferior and temporal limbus were collected using the Heidelberg Retina Tomograph III Rostock Corneal Module. Basal cell density in all locations was measured by two independent observers. Results The mean basal cell density of the normal group was 9264 ±598 cells/mm2 in the cornea and 7120 ±362 cells/mm2 in the limbus. In the LSCD group, the mean basal cell density in the cornea decreased 31.0% (6389 ±1820 cells/mm2, p<0.001) and in the limbus decreased 23.6% (5440 ±1123 cells/mm2, p<0.001) compared to that in the control. There was a trend of basal cell density decline in more advanced stage of LSCD. The basal cell density declined in the unaffected regions at a similar degree as that in the affected region in sectoral LSCD (p>0.05). The basal cell diameter increased by 24.6% in the cornea (14.7 μm) and by 15.7% in the limbus (15.5 μm) compared to the control. Conclusions Basal cell density in both central cornea and limbus decreases in LSCD. LSCs are affected globally and basal cell density could be used as a parameter to measure LSC function at the early stages of the disease process. PMID:26149968

  15. Quinones and halogenated monoterpenes of algal origin show anti-proliferative effects against breast cancer cells in vitro.

    PubMed

    de la Mare, Jo-Anne; Lawson, Jessica C; Chiwakata, Maynard T; Beukes, Denzil R; Edkins, Adrienne L; Blatch, Gregory L

    2012-12-01

    Red and brown algae have been shown to produce a variety of compounds with chemotherapeutic potential. A recent report described the isolation of a range of novel polyhalogenated monoterpene compounds from the red algae Plocamium corallorhiza and Plocamium cornutum collected off the coast of South Africa, together with the previously described tetraprenylquinone, sargaquinoic acid (SQA), from the brown algae Sargassum heterophyllum. In our study, the algal compounds were screened for anti-proliferative activity against metastatic MDA-MB-231 breast cancer cells revealing that a number of compounds displayed anti-cancer activity with IC(50) values in the micromolar range. A subset of the compounds was tested for differential toxicity in the MCF-7/MCF12A system and five of these, including sargaquinoic acid, were found to be at least three times more toxic to the breast cancer than the non-malignant cell line. SQA was further analysed in terms of its mechanism of cytotoxicity in MDA-MB-231 cells. The ability to initiate apoptosis was distinguished from the induction of an inflammatory necrotic response via flow cytometry with propidium iodide and Hoescht staining, confocal microscopy with Annexin V and propidium iodide staining as well as the PARP cleavage assay. We report that SQA induced apoptosis while a polyhalogenated monoterpene RU015 induced necrosis in metastatic breast cancer cells in vitro. Furthermore, we demonstrated that apoptosis induction by SQA occurs via caspase-3, -6, -8, -9 and -13 and was associated with down-regulation of Bcl-2. In addition, cell cycle analyses revealed that the compound causes G(1) arrest in MDA-MB-231 cells. PMID:22249429

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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. PMID:24771029

  2. 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

  3. 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.

  4. 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. PMID:22528997

  5. Algal sulfated carrageenan inhibits proliferation of MDA-MB-231 cells via apoptosis regulatory genes.

    PubMed

    Murad, Hossam; Ghannam, Ahmed; Al-Ktaifani, Mahmoud; Abbas, Assef; Hawat, Mohammad

    2015-03-01

    Marine algae are prolific sources of sulfated polysaccharides, which may explain the low incidence of certain cancers in countries that traditionally consume marine food. Breast cancer is one of the most common types of non‑skin cancer in females. In this study, extracted sulfated carrageenan (ESC), predominantly consisting of ι‑carrageenan extracted from the red alga Laurencia papillosa, was characterized using Fourier transform infrared spectrometry. The biological effects of the identified extract were investigated and its potential cytotoxic activity was tested against the MDA‑MB‑231 cancer cell line. The biological biometer of the inhibitory concentration of the polysaccharide‑treated MDA‑MB‑231 cells was determined as 50 µM. Treatment with 50 µM ESC inhibited cell proliferation and promptly induced cell death through nuclear condensation and DNA fragmentation. Characterization of polysaccharide‑treated MDA‑MB‑231 cell death revealed that induction of apoptosis occurred via the activation of the extrinsic apoptotic caspase‑8 gene. The apoptotic signaling pathway was regulated through caspase‑3, caspase‑9, p53, Bax and Bcl‑2 genes. These findings suggest that ESC may serve as a potential therapeutic agent to target breast cancer via prompting apoptosis. PMID:25384757

  6. The algal metabolite yessotoxin affects heterogeneous nuclear ribonucleoproteins in HepG2 cells.

    PubMed

    Young, Clifford; Truman, Penelope; Boucher, Magalie; Keyzers, Robert A; Northcote, Peter; Jordan, T William

    2009-05-01

    The dinoflagellate metabolite yessotoxin (YTX) is produced by several species of algae and accumulates in marine food chains, leading to concerns about possible affects on aquaculture industries and human health. In mice used for toxicity testing, YTX is lethal by the intraperitoneal route, but is considerably less toxic when orally administered. The mode of action of YTX and its potential effect on humans is unclear and we therefore conducted the first proteomic analysis of the effects of this compound. We used 2-DE to examine protein changes in HepG2 cell cultures exposed to 1.4 microM YTX for 3, 12.5, 18 and 24 h. After selecting proteins that changed more than three-fold after YTX exposure, 55 spots were deemed significantly affected by the toxin (p<0.05). Major groups of affected proteins include members from the heterogeneous nuclear ribonucleoprotein (hnRNP), lamin, cathepsin and heat shock protein families that often are associated with apoptosis. We therefore confirmed apoptosis using Annexin-V-FLUOS staining of phosphatidylserine exposed at the surface of apoptotic cells. Ingenuity pathways analysis also indicated effects on pathways involved in protein processing, cell cycling and cell death. PMID:19343718

  7. Algal Flocculation with Synthetic Organic Polyelectrolytes

    PubMed Central

    Tenney, Mark W.; Echelberger, Wayne F.; Schuessler, Ronald G.; Pavoni, Joseph L.

    1969-01-01

    The feasibility of removing algae from water and wastewater by chemical flocculation techniques was investigated. Mixed cultures of algae were obtained from both continuous- and batch-fed laboratory reactors. Representative cationic, anionic, and nonionic synthetic organic polyelectrolytes were used as flocculants. Under the experimental conditions, chemically induced algal flocculation occurred with the addition of cationic polyelectrolyte, but not with anionic or nonionic polymers, although attachment of all polyelectrolyte species to the algal surface is shown. The mechanism of chemically induced algal flocculation is interpreted in terms of bridging phenomena between the discrete algal cells and the linearly extended polymer chains, forming a three-dimensional matrix that is capable of subsiding under quiescent conditions. The degree of flocculation is shown to be a direct function of the extent of polymer coverage of the active sites on the algal surface, although to induce flocculation by this method requires that the algal surface charge must concurrently be reduced to a level at which the extended polymers can bridge the minimal distance of separation imposed by electrostatic repulsion. The influence of pH, algal concentration, and algal growth phase on the requisite cationic flocculant dose is also reported. PMID:5370666

  8. Organelle interactions and possible degradation pathways visualized in high-pressure frozen algal cells.

    PubMed

    Aichinger, N; Lütz-Meindl, U

    2005-08-01

    Summary Organelle interactions, although essential for both anabolic and catabolic pathways in plant cells have not been examined in detail so far. In the present study the structure of different organelle-organelle, organelle-vesicle and organelle-membrane interactions were investigated in growing and nongrowing cells of the green alga Micrasterias denticulata by use of high pressure freeze fixation and energy filtering transmission electron microscopy. It became clear that contacts between mitochondria always occur by formation of a cone-shaped protuberance of one of the mitochondria which penetrates into its fusion partner. In the same way, structural interactions between mitochondria and mucilage vesicles and between microbodies and mucilage vesicles are achieved. Lytic compartments contact mitochondria or mucilage vesicles again by forming protuberances and by extending their contents into the respective compartment. Detached portions of mitochondria are found inside lytic compartments as a consequence of such interactions. Mitochondria found in contact with the plasma membrane reveal structural disintegration. Our study shows that interactions of organelles and vesicles are frequent events in Micrasterias cells of different ages. The interactive contacts between lytic compartments and organelles or vesicles suggest a degradation pathway different from autophagy processes described in the literature. Both the interactions between vesicles and organelles and the degradation pathways occur independently from cytoskeleton function as demonstrated by use of cytochalasin D and the microtubule inhibitor amiprophos-methyl. PMID:16159344

  9. A portable Raman acoustic levitation spectroscopic system for the identification and environmental monitoring of algal cells.

    PubMed

    Wood, Bayden R; Heraud, Philip; Stojkovic, Slobodanka; Morrison, Danielle; Beardall, John; McNaughton, Don

    2005-08-01

    We report the coupling of a portable Raman spectrometer to an acoustic levitation device to enable environmental monitoring and the potential taxonomic identification of microalgae. Spectra of living cells were recorded at 785 nm using a fiber-optic probe coupled to a portable Raman spectrometer. The spectra exhibit an excellent signal-to-noise ratio and clearly show bands from chlorophyll a and beta-carotene. Spectra of levitated photobleached microalgae clearly show a reduction in chlorophyll a concentration relative to beta-carotene after 10 min of exposure to a quartz halogen lamp. Spectra recorded from levitated nitrogen-limited cells also show a significant reduction in bands associated with chlorophyll a, as compared to nitrogen-replete cells. To investigate the diagnostic capability of the technique, four species of microalgae were analyzed. Good quality spectra of all four species were obtained showing varying ratios of beta-carotene to chlorophyll. The combination of an acoustic levitation device and a portable Raman spectrometer shows potential as a taxonomic and environmental monitoring tool with direct application to field studies in remote environments. PMID:16053309

  10. Cryopreservation of Chlamydomonas reinhardtii: a cause of low viability at high cell density.

    PubMed

    Piasecki, Brian P; Diller, Kenneth R; Brand, Jerry J

    2009-02-01

    Cryopreservation is a practical method for stabilizing the genetic content of living algae over long periods of time. Yet, Chlamydomonas reinhardtii, the algal species most often utilized in studies requiring genetically defined strains, is difficult to cryopreserve with a consistently high post-thaw viability. Work described here demonstrates that C. reinhardtii retains high viability only when cryopreserved at a low cell density. Low viability at high cell density was caused by the release of an injurious substance into the culture medium. Rapid freezing and thawing under non-cryoprotective conditions released large amounts of the injurious substance. Heat denaturation of cells prevented the release of the injurious substance, but heating did not inactivate it after it was released. Even when concentrated, the injurious substance was non-toxic to cells under normal culture conditions. Reduced viability of cells cryopreserved in the presence of the injurious substance could not be attributed to changes in the tonicity of the medium. A mutant strain of C. reinhardtii (cw10) with a greatly diminished cell wall did not release a substance that reduced the post-thaw viability of wild-type or cw10 cryopreserved cells. Cryopreservation of cw10 cells was achieved with approximately the same post-thaw viability irrespective to the cell concentration at the time of freezing. Acid treatment of the injurious substance was able to partially diminish its injurious effect on cells during cryopreservation. We propose that diminished viability of C. reinhardtii cells cryopreserved at high cell densities is caused by the enzymatic release of a cell-wall component. PMID:19041638

  11. Docosahexaenoic acid (DHA) and docosapentaenoic acid (DPAn-6) algal oils reduce inflammatory mediators in human peripheral mononuclear cells in vitro and paw edema in vivo.

    PubMed

    Nauroth, Julie M; Liu, Ying Chun; Van Elswyk, Mary; Bell, Rebecca; Hall, Eileen Bailey; Chung, Gloria; Arterburn, Linda M

    2010-05-01

    The anti-inflammatory activity associated with fish oil has been ascribed to the long-chain polyunsaturated fatty acids (LC-PUFA), predominantly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Here we examined the anti-inflammatory effects of two DHA-rich algal oils, which contain little EPA, and determined the contribution of the constituent fatty acids, particularly DHA and docosapentaenoic acid (DPAn-6). In vitro, lipopolysaccharide (LPS)-stimulated Interleukin-1 beta (IL-1beta) and Tumor Necrosis Factor-alpha (TNF-alpha) secretion in human peripheral blood mononuclear cells (PBMC) was inhibited with apparent relative potencies of DPAn-6 (most potent) > DHA > EPA. In addition, DPAn-6 decreased intracellular levels of cyclooxygenase-2 (COX-2) and was a potent inhibitor of pro-inflammatory prostaglandin E2 (PGE2) production. DHA/DPAn-6-rich DHA-S (DHA-S) algal oil was more effective at reducing edema in rats than DHA-rich DHA-T (DHA-T), suggesting that DPAn-6 has anti-inflammatory properties. Further in vivo analyses demonstrated that feeding DPAn-6 alone, provided as an ethyl ester, reduced paw edema to an extent approaching that of indomethacin and enhanced the anti-inflammatory activity of DHA when given in combination. Together, these results demonstrate that DPAn-6 has anti-inflammatory activity and enhances the effect of DHA in vitro and in vivo. Thus, DHA-S algal oil may have potential for use in anti-inflammatory applications. PMID:20364438

  12. Influence of zwitterionic SAMs on protein adsorption and the attachment of algal cells.

    PubMed

    Bauer, Stella; Alles, Maria; Finlay, John A; Callow, James A; Callow, Maureen E; Rosenhahn, Axel

    2014-01-01

    Zwitterionic polymers are non-fouling materials with immense potential for a range of biological applications. Here, we describe the resistance of zwitterionic self-assembled monolayers prepared from different solution ratios of positively and negatively charged thiols towards the adhesion of proteins, zoospores of the green alga Ulva linza, and cells of the unicellular alga Navicula perminuta. While mixed zwitterionic surfaces with a high hydrophilic nature significantly reduced the adhesion strength of the two algae, the positively and negatively charged components were far less effective. PMID:24955504

  13. 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. PMID:27348194

  14. 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.

  15. 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.

  16. 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.

  17. Nanostructured magnesium increases bone cell density

    NASA Astrophysics Data System (ADS)

    Weng, Lucy; Webster, Thomas J.

    2012-12-01

    Magnesium has attracted some attention in orthopedics due to its biodegradability and mechanical properties. Since magnesium is an essential natural mineral for bone growth, it can be expected that as a biomaterial, it would support bone formation. However, upon degradation in the body, magnesium releases OH- which results in an alkaline pH that can be detrimental to cell density (for example, osteoblasts or bone forming cells). For this reason, modification of magnesium may be necessary to compensate for such detrimental effects to cells. This study created biologically inspired nanoscale surface features on magnesium by soaking magnesium in various concentrations of NaOH (from 1 to 10 N) and for various periods of time (from 10 to 30 min). The results provided the first evidence of increased roughness, surface energy, and consequently greater osteoblast adhesion, after 4 h as well as density up to 7 days on magnesium treated with any concentration of NaOH for any length of time compared to untreated controls. For these reasons, this study suggests that soaking magnesium in NaOH could be an inexpensive, simple and effective manner to promote osteoblast functions for numerous orthopedic applications and, thus, should be further studied.

  18. 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...

  19. Microflotation performance for algal separation.

    PubMed

    Hanotu, James; Bandulasena, H C Hemaka; Zimmerman, William B

    2012-07-01

    The performance of microflotation, dispersed air flotation with microbubble clouds with bubble size about 50 µm, for algae separation using fluidic oscillation for microbubble generation is investigated. This fluidic oscillator converts continuous air supply into oscillatory flow with a regular frequency to generate bubbles of the scale of the exit pore. Bubble characterization results showed that average bubble size generated under oscillatory air flow state was 86 µm, approximately twice the size of the diffuser pore size of 38 µm. In contrast, continuous air flow at the same rate through the same diffusers yielded an average bubble size of 1,059 µm, 28 times larger than the pore size. Following microbubble generation, the separation of algal cells under fluidic oscillator generated microbubbles was investigated by varying metallic coagulant types, concentration and pH. Best performances were recorded at the highest coagulant dose (150 mg/L) applied under acidic conditions (pH 5). Amongst the three metallic coagulants studied, ferric chloride yielded the overall best result of 99.2% under the optimum conditions followed closely by ferric sulfate (98.1%) and aluminum sulfate with 95.2%. This compares well with conventional dissolved air flotation (DAF) benchmarks, but has a highly turbulent flow, whereas microflotation is laminar with several orders of magnitude lower energy density. PMID:22290221

  20. Formation of harmful algal blooms cannot be explained by allelopathic interactions

    PubMed Central

    Jonsson, Per R.; Pavia, Henrik; Toth, Gunilla

    2009-01-01

    Many planktonic microalgae produce a range of toxins and may form harmful algal blooms. One hypothesis is that some toxins are allelopathic, suppressing the growth of competitors, and it has been suggested that allelopathy may be one important mechanism causing algal blooms. In a metaanalysis of recent experimental work, we looked for evidence that allelopathy may explain the initiation of algal blooms. With few exceptions, allelopathic effects were only significant at very high cell densities typical of blooms. We conclude that there is no experimental support for allelopathy at prebloom densities, throwing doubts on allelopathy as a mechanism in bloom formation. Most studies tested allelopathy using cell-free manipulations. With simple models we show that cell-free manipulations may underestimate allelopathy at low cell densities if effects are transmitted during cell–cell interactions. However, we suggest that the evolution of allelopathy under field conditions may be unlikely even if based on cell–cell interactions. The spatial dispersion of cells in turbulent flow will make it difficult for an allelopathic cell to receive an exclusive benefit, and a dispersion model shows that dividing cells are rapidly separated constraining clone selection. Instead, we propose that reported allelopathic effects may be nonadaptive side effects of predator–prey or casual parasitic cell–cell interactions. PMID:19549831

  1. 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.

  2. Algal Data from Selected Sites in the Upper Colorado River Basin, Colorado, Water Years 1996-97

    USGS Publications Warehouse

    Mize, Scott V.; Deacon, Jeffrey R.

    2001-01-01

    Algal community samples were collected at 15 sites in the Upper Colorado River Basin in Colorado as part of the National Water-Quality Assessment Program during water years 1996-97. Sites sampled were located in two physiographic provinces, the Southern Rocky Mountains and the Colorado Plateaus, and represented agricultural, mining, urban, and mixed land uses and background conditions. Algal samples were collected once per year during low-flow conditions. Quantitative algal samples were collected within two targeted instream habitat types including a taxonomically richest-targeted habitat and a depositional-targeted habitat. This report presents the algal community data collected at the fixed sites in the Upper Colorado River Basin study unit. Algal data include densities (abundance of cells per square centimeter of substrate) and biovolumes (cubic micrometers of cells per square centimeter of substrate) for the two habitat types. Quality-assurance and quality-control results for algal samples indicate that the largest sampling variability tends to occur in samples from small streams.

  3. Optimizing algal cultivation & productivity : an innovative, multidiscipline, and multiscale approach.

    SciTech Connect

    Murton, Jaclyn K.; Hanson, David T.; Turner, Tom; Powell, Amy Jo; James, Scott Carlton; Timlin, Jerilyn Ann; Scholle, Steven; August, Andrew; Dwyer, Brian P.; Ruffing, Anne; Jones, Howland D. T.; Ricken, James Bryce; Reichardt, Thomas A.

    2010-04-01

    Progress in algal biofuels has been limited by significant knowledge gaps in algal biology, particularly as they relate to scale-up. To address this we are investigating how culture composition dynamics (light as well as biotic and abiotic stressors) describe key biochemical indicators of algal health: growth rate, photosynthetic electron transport, and lipid production. Our approach combines traditional algal physiology with genomics, bioanalytical spectroscopy, chemical imaging, remote sensing, and computational modeling to provide an improved fundamental understanding of algal cell biology across multiple cultures scales. This work spans investigations from the single-cell level to ensemble measurements of algal cell cultures at the laboratory benchtop to large greenhouse scale (175 gal). We will discuss the advantages of this novel, multidisciplinary strategy and emphasize the importance of developing an integrated toolkit to provide sensitive, selective methods for detecting early fluctuations in algal health, productivity, and population diversity. Progress in several areas will be summarized including identification of spectroscopic signatures for algal culture composition, stress level, and lipid production enabled by non-invasive spectroscopic monitoring of the photosynthetic and photoprotective pigments at the single-cell and bulk-culture scales. Early experiments compare and contrast the well-studied green algae chlamydomonas with two potential production strains of microalgae, nannochloropsis and dunnaliella, under optimal and stressed conditions. This integrated approach has the potential for broad impact on algal biofuels and bioenergy and several of these opportunities will be discussed.

  4. 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.

  5. 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. PMID:26689663

  6. 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.

  7. Harmful Algal Blooms (HABs)

    MedlinePlus

    ... Topics Eighth Annual National Conference on Health Communication, Marketing & Media August 19-21, 2014 Atlanta, GA Harmful Algal Blooms Recommend on Facebook Tweet Share Compartir On this Page What's the ...

  8. 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.

  9. Variation of algal viability during electrochemical disinfection using Ti/RuO2 electrodes.

    PubMed

    Liang, Wenyan; Wang, Ke; Chen, Li; Ruan, Lingling; Sui, Lili

    2011-01-01

    This paper studied the influence of the operating conditions, e.g., current density, electrolyte and exposure time, on the variation of the algal viability during electrochemical disinfection processes. An electrochemical tube employing Ti/RuO2 as anodes was constructed for inactivation of cyanobacteria (often called blue-green algae) Microcystis aeruginosa. Viability of algal cells was determined by 2,3,5-triphenyl-tetrazoliumchloride (TTC) dehydrogenase activity assay and neutral red (NR) staining assay. Algal suspensions with cell density of 5-7 x 10(9) L(-1) were exposed to current densities from 1 to 8 mA cm(-2) at room temperature (25-30 degrees C) for 30 min. The results showed that the cell viability decreased obviously with the increase of current density. After exposure to 4 mA cm(-2) for more than 7 min, Microcystis aeruginosa didn't have the ability to resume growth. Comparative disinfection tests with different electrolytes were conducted, including chlorides, sulfates, nitrates and phosphates. Microcystis aeruginosa appeared to be sensitive to electro-generated chlorine oxidants. The inactivation effect was also demonstrated to occur in chlorine-free electrolytes. However, decrease of the inactivation effect by adding ascorbic acid as an oxidant scavenger indicated that the reactive oxygen species, especially *OH radicals, played an important role for chlorine-free electrolytes. PMID:22053471

  10. 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)

  11. 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. PMID:26188984

  12. Method and system of culturing an algal mat

    SciTech Connect

    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.

  13. High power density molten carbonate fuel cells

    SciTech Connect

    Bloom, I.; Johnson, S.A.; Geyer, H.K.; Roche, M.F.; Krumpelt, M.; Myles, K.M.

    1995-07-01

    Our results to date indicate that the specific power of the MCFC can be increased from 1200 W/m{sup 2} to above 2000W/m{sup 2} through the use of advanced components such as the double doped LiFeO{sub 2} cathode and pressurized operation. Its volumetric power density can also be increased by an additional 60% by multiple manifolding. Therefore, MCFCs with two to three times the power density of the current generation of MCFCs are possible.

  14. 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.

  15. 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. PMID:26018284

  16. Ultraviolet radiation dose calculation for algal suspensions using UVA and UVB extinction coefficients.

    PubMed

    Navarro, Enrique; Muñiz, Selene; Korkaric, Muris; Wagner, Bettina; de Cáceres, Miquel; Behra, Renata

    2014-03-01

    Although the biological importance of ultraviolet light (UVR) attenuation has been recognised in marine and freshwater environments, it is not generally considered in in vitro ecotoxicological studies using algal cell suspensions. In this study, UVA and UVB extinction were determined for cultures of algae with varying cell densities, and the data were used to calculate the corresponding extinction coefficients for both UVA and UVB wavelength ranges. Integrating the Beer-Lambert equation to account for changes in the radiation intensity reaching each depth, from the surface until the bottom of the experimental vessel, we obtained the average UVA and UVB intensity to which the cultured algal cells were exposed. We found that UVR intensity measured at the surface of Chlamydomonas reinhardtii cultures lead to a overestimation of the UVR dose received by the algae by 2-40 times. The approach used in this study allowed for a more accurate estimation of UVA and UVB doses. PMID:24607609

  17. 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.

  18. 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.

  19. Impact of cell density on microbially induced stable isotope fractionation.

    PubMed

    Kampara, Makeba; Thullner, Martin; Harms, Hauke; Wick, Lukas Y

    2009-01-01

    Quantification of microbial contaminant biodegradation based on stable isotope fractionation analysis (SIFA) relies on known, invariable isotope fractionation factors. The microbially induced isotope fractionation is caused by the preferential cleavage of bonds containing light rather than heavy isotopes. However, a number of non-isotopically sensitive steps preceding the isotopically sensitive bond cleavage may affect the reaction kinetics of a degradation process and reduce the observed (i.e., the macroscopically detectable) isotope fractionation. This introduces uncertainty to the use of isotope fractionation for the quantification of microbial degradation processes. Here, we report on the influence of bacterial cell density on observed stable isotope fractionation. Batch biodegradation experiments were performed under non-growth conditions to quantify the toluene hydrogen isotope fractionation by exposing Pseudomonas putida mt-2(pWWO) at varying cell densities to different concentrations of toluene. Observed isotope fractionation depended significantly on the cell density. When the cell density rose from 5 x 10(5) to 5 x 10(8)cells/mL, the observed isotope fractionation declined by 70% and went along with a 55% decrease of the degradation rates of individual cells. Theoretical estimates showed that uptake-driven diffusion to individual cells depended on cell density via the overlap of the cells' diffusion-controlled boundary layers. Our data suggest that biomass effects on SIFA have to be considered even in well-mixed systems such as the cell suspensions used in this study. PMID:19015849

  20. 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. PMID:27071311

  1. 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. PMID:26271287

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Sub-plasmalemmal linear density: a common structure in globoid cells and mesenchymal cells.

    PubMed

    Yajima, K; Fletcher, T F; Suzuki, K

    1977-08-31

    Sub-plasmalemmal linear densities of variable length (0.1 approximately 1.0 mu) were found to be a constant feature of globoid cells in human as well as in canine globoid cell leukodystrophy (GLD). Similar densities were also observed in experimental globoid cells and epithelioid cells in chronic granuloma but not in glial cells. The linear densities always appeared without any relation to basal laminae. These observations together with the other reports of similar structures in lymphoma, fibroma and sarcoidosis suggest that the sub-plasmalemmal density is a structure frequently observed in mesenchymal cells, and may be another supporting feature for possible mesenchymal origin of globoid cells. PMID:906802

  7. 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.

  8. Change in Photosystem II Photochemistry During Algal Growth Phases of Chlorella vulgaris and Scenedesmus obliquus.

    PubMed

    Oukarroum, Abdallah

    2016-06-01

    Sensitivity of photosynthetic processes towards environmental stress is used as a bioanalytical tool to evaluate the responses of aquatic plants to a changing environment. In this paper, change of biomass density, chlorophyll a fluorescence and photosynthetic parameters during growth phases of two microalgae Chlorella vulgaris and Scenedesmus obliquus were studied. The photosynthetic growth behaviour changed significantly with cell age and algae species. During the exponential phase of growth, the photosynthesis capacity reached its maximum and decreased in ageing algal culture during stationary phase. In conclusion, the chlorophyll a fluorescence OJIP method and the derived fluorescence parameters would be an accurate method for obtaining information on maximum photosynthetic capacities and monitoring algal cell growth. This will contribute to more understanding, for example, of toxic actions of pollutants in microalgae test. PMID:26868257

  9. Algal functional annotation tool

    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 tomore » 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

  10. 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

  11. Zinc-oxygen primary cell yields high energy density

    NASA Technical Reports Server (NTRS)

    Graff, C. B.

    1968-01-01

    Zinc-oxygen primary cell yields high energy density for battery used as an auxiliary power source in space vehicle systems. Maximum reliability and minimum battery weight is achieved by using a stacking configuration of 23 series-connected modules with 6 parallel-connected cells per module.

  12. 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.

  13. Corneal Endothelial Cell Density and Morphology in Healthy Turkish Eyes

    PubMed Central

    Arıcı, Ceyhun; Arslan, Osman Sevki; Dikkaya, Funda

    2014-01-01

    Purpose. To describe the normative values of corneal endothelial cell density, morphology, and central corneal thickness in healthy Turkish eyes. Methods. Specular microscopy was performed in 252 eyes of 126 healthy volunteers (M : F, 42 : 84). Parameters studied included mean endothelial cell density (MCD), mean cell area (MCA), coefficient of variation (CV) in cell size, percentage of hexagonal cells, and central corneal thickness (CCT). Results. The mean age of volunteers was 44.3 ± 13.5 (range, 20 to 70) years. There was a statistically significant decrease in MCD (P < 0.001; correlation, −0.388) and percentage of hexagonal cells, (P < 0.001; correlation, −0.199) with age. There was also a statistically significant increase in MCA (P < 0.001; correlation, 0.363) with increasing age. There was no statistically significant difference in MCD, MCA, CV in cell size, percentage of hexagonal cells, and CCT between genders and there was also no significant difference in these parameters between fellow eyes of subjects. Conclusions. Normotive data for the endothelium in the Turkish population are reported. Endothelial cell density in the Turkish eyes is less than that described in the Japanese, American, Chinese, and Filipino eyes and higher than that described in Indian, Thai, and Iranian eyes. PMID:24683494

  14. 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

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

    PubMed

    Reyes-Haro, Daniel; 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

  16. 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.

  17. High power density yeast catalyzed microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Ganguli, Rahul

    Microbial fuel cells leverage whole cell biocatalysis to convert the energy stored in energy-rich renewable biomolecules such as sugar, directly to electrical energy at high efficiencies. Advantages of the process include ambient temperature operation, operation in natural streams such as wastewater without the need to clean electrodes, minimal balance-of-plant requirements compared to conventional fuel cells, and environmentally friendly operation. These make the technology very attractive as portable power sources and waste-to-energy converters. The principal problem facing the technology is the low power densities compared to other conventional portable power sources such as batteries and traditional fuel cells. In this work we examined the yeast catalyzed microbial fuel cell and developed methods to increase the power density from such fuel cells. A combination of cyclic voltammetry and optical absorption measurements were used to establish significant adsorption of electron mediators by the microbes. Mediator adsorption was demonstrated to be an important limitation in achieving high power densities in yeast-catalyzed microbial fuel cells. Specifically, the power densities are low for the length of time mediator adsorption continues to occur. Once the mediator adsorption stops, the power densities increase. Rotating disk chronoamperometry was used to extract reaction rate information, and a simple kinetic expression was developed for the current observed in the anodic half-cell. Since the rate expression showed that the current was directly related to microbe concentration close to the electrode, methods to increase cell mass attached to the anode was investigated. Electrically biased electrodes were demonstrated to develop biofilm-like layers of the Baker's yeast with a high concentration of cells directly connected to the electrode. The increased cell mass did increase the power density 2 times compared to a non biofilm fuel cell, but the power density

  18. Molten carbonate fuel cell with high power density

    SciTech Connect

    Krumpelt, M.; Roche, M.F.; Bloom, I.; Geyer, H.; Johnson, S.

    1994-08-01

    The objective of this research is a doubling of the current density of the molten carbonate fuel cell (MCFC) from the present value of 1600A/m{sup 2} to 3200 A/m{sup 2} and a similar increase in the volumetric power density. This project is linked to other projects concerning MCFCs (one on the multiply manifolded MCFCs, the other on lithium ferrate and lithium cobaltate cathodes for MCFCs).

  19. 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. PMID:27431921

  20. 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. PMID:27148719

  1. 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.

  2. 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. PMID:21330711

  3. Isolation of Lipid Droplets from Cells by Density Gradient Centrifugation.

    PubMed

    Brasaemle, Dawn L; Wolins, Nathan E

    2016-01-01

    Lipid droplets are organelles found in most mammalian cells, as well as in various plant tissues and yeast. They are composed of a core of neutral lipids surrounded by a membrane monolayer of phospholipids and cholesterol in which specific proteins are embedded. This unit provides protocols for isolating lipid droplets from mammalian cells by discontinuous density gradient centrifugation. © 2016 by John Wiley & Sons, Inc. PMID:27580706

  4. Algal morphogenesis: modelling interspecific variation in Micrasterias with reaction--diffusion patterned catalysis of cell surface growth

    PubMed Central

    Holloway, D. M.

    1999-01-01

    Semi-cell morphogenesis in unicellular desmid algae of the genus Micrasterias generates a stellar shape by repeated dichotomous branching of growing tips of the cell surface. The numerous species of the genus display variations of the branching pattern that differ markedly in number of branchings, lobe width and lobe length. We have modelled this morphogenesis, following previous work by D. M. Harrison and M. Kolar (1988), on the assumptions that patterning occurs by chemical reaction-diffusion activity within the plasma membrane, leading to morphological expression by patterned catalysis of the extension of the cell surface. The latter has been simulated in simplified form by two-dimensional computations. Our results indicate that for generation of repeated branchings and for the control of diverse species-specific shapes, the loss of patterning activity and of rapid growth in regions separating the active growing tips is an essential feature. We believe this conclusion to be much more general than the specific details of our model. We discuss the limitations of the model especially in terms of what extra features might be addressed in three-dimensional computation.

  5. Measuring cellular-scale nutrient distribution in algal biofilms with synchrotron confocal infrared microspectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infrared microspectroscopy (IMS) and chemical imaging is ideal for measuring nutrient distribution in single algal cells on a cellular and subcellular level. The study of small algal cells, or cells within a colony requires enhanced spatial resolution IMS. Synchrotron infrared microspectroscopy wit...

  6. A random graph model of density thresholds in swarming cells.

    PubMed

    Jena, Siddhartha G

    2016-03-01

    Swarming behaviour is a type of bacterial motility that has been found to be dependent on reaching a local density threshold of cells. With this in mind, the process through which cell-to-cell interactions develop and how an assembly of cells reaches collective motility becomes increasingly important to understand. Additionally, populations of cells and organisms have been modelled through graphs to draw insightful conclusions about population dynamics on a spatial level. In the present study, we make use of analogous random graph structures to model the formation of large chain subgraphs, representing interactions between multiple cells, as a random graph Markov process. Using numerical simulations and analytical results on how quickly paths of certain lengths are reached in a random graph process, metrics for intercellular interaction dynamics at the swarm layer that may be experimentally evaluated are proposed. PMID:26893102

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

    SciTech Connect

    Lu, Hongxu; Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 ; Guo, Likun; National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road, Chengdu 610064 ; Wozniak, Michal J.; Kawazoe, Naoki; International Center for Materials Nanoarchitectonics , National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 ; Tateishi, Tetsuya; Zhang, Xingdong; Chen, Guoping; Biomaterials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044; International Center for Materials Nanoarchitectonics , National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044

    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.

  8. A novel direct ethanol fuel cell with high power density

    NASA Astrophysics Data System (ADS)

    An, L.; Zhao, T. S.; Chen, R.; Wu, Q. X.

    2011-08-01

    A new type of direct ethanol fuel cell (DEFC) that is composed of an alkaline anode and an acid cathode separated with a charger conducting membrane is developed. Theoretically it is shown that the voltage of this novel fuel cell is 2.52 V, while, experimentally it has been demonstrated that this fuel cell can yield an open-circuit voltage (OCV) of 1.60 V and a peak power density of 240 mW cm-2 at 60 °C, which represent the highest performance of DEFCs that has so far been reported in the open literature.

  9. 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. PMID:464015

  10. Regional Alterations in Purkinje Cell Density in Patients with Autism

    PubMed Central

    Skefos, Jerry; Cummings, Christopher; Enzer, Katelyn; Holiday, Jarrod; Weed, Katrina; Levy, Ezra; Yuce, Tarik; Kemper, Thomas; Bauman, Margaret

    2014-01-01

    Neuropathological studies, using a variety of techniques, have reported a decrease in Purkinje cell (PC) density in the cerebellum in autism. We have used a systematic sampling technique that significantly reduces experimenter bias and variance to estimate PC densities in the postmortem brains of eight clinically well-documented individuals with autism, and eight age- and gender-matched controls. Four cerebellar regions were analyzed: a sensorimotor area comprised of hemispheric lobules IV–VI, crus I & II of the posterior lobe, and lobule X of the flocculonodular lobe. Overall PC density was thus estimated using data from all three cerebellar lobes and was found to be lower in the cases with autism as compared to controls, an effect that was most prominent in crus I and II (p<0.05). Lobule X demonstrated a trend towards lower PC density in only the males with autism (p = 0.05). Brain weight, a correlate of tissue volume, was found to significantly contribute to the lower lobule X PC density observed in males with autism, but not to the finding of lower PC density in crus I & II. Therefore, lower crus I & II PC density in autism is more likely due to a lower number of PCs. The PC density in lobule X was found to correlate with the ADI-R measure of the patient's use of social eye contact (R2 = −0.75, p = 0.012). These findings support the hypothesis that abnormal PC density may contribute to selected clinical features of the autism phenotype. PMID:24586223

  11. 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

  12. Algal functional annotation tool

    SciTech Connect

    Lopez, D.; Casero, D.; Cokus, S. J.; Merchant, S. S.; Pellegrini, M.

    2012-07-01

    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 pathway maps and batch gene identifier conversion.

  13. 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.

  14. High-density lipoprotein endocytosis in endothelial cells

    PubMed Central

    Fruhwürth, Stefanie; Pavelka, Margit; Bittman, Robert; Kovacs, Werner J; Walter, Katharina M; Röhrl, Clemens; Stangl, Herbert

    2013-01-01

    AIM: To describe the way stations of high-density lipoprotein (HDL) uptake and its lipid exchange in endothelial cells in vitro and in vivo. METHODS: A combination of fluorescence microscopy using novel fluorescent cholesterol surrogates and electron microscopy was used to analyze HDL endocytosis in great detail in primary human endothelial cells. Further, HDL uptake was quantified using radio-labeled HDL particles. To validate the in vitro findings mice were injected with fluorescently labeled HDL and particle uptake in the liver was analyzed using fluorescence microscopy. RESULTS: HDL uptake occurred via clathrin-coated pits, tubular endosomes and multivesicular bodies in human umbilical vein endothelial cells. During uptake and resecretion, HDL-derived cholesterol was exchanged at a faster rate than cholesteryl oleate, resembling the HDL particle pathway seen in hepatic cells. In addition, lysosomes were not involved in this process and thus HDL degradation was not detectable. In vivo, we found HDL mainly localized in mouse hepatic endothelial cells. HDL was not detected in parenchymal liver cells, indicating that lipid transfer from HDL to hepatocytes occurs primarily via scavenger receptor, class B, type I mediated selective uptake without concomitant HDL endocytosis. CONCLUSION: HDL endocytosis occurs via clathrin-coated pits, tubular endosomes and multivesicular bodies in human endothelial cells. Mouse endothelial cells showed a similar HDL uptake pattern in vivo indicating that the endothelium is one major site of HDL endocytosis and transcytosis. PMID:24340136

  15. 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. PMID:24321283

  16. T cells, mast cells and microvascular density in diffuse large B cell lymphoma.

    PubMed

    Marinaccio, Christian; Ingravallo, Giuseppe; Gaudio, Francesco; Perrone, Tommasina; Ruggieri, Simona; Opinto, Giuseppina; Nico, Beatrice; Maiorano, Eugenio; Specchia, Giorgina; Ribatti, Domenico

    2016-08-01

    Diffuse large B cell lymphoma (DLBCL) is recognized as the most common form of non-Hodgkin lymphoma (NHL), accounting for about 40 % of all cases of NHL. Among the cellular components of the tumor inflammatory infiltrate, T cells and mast cells have been demonstrated to be correlated with tumor angiogenesis. In this report, we have investigated CD3 and tryptase expression and their relationship with microvascular density (MVD) in DLBCL patients. Moreover, we determined the significance of CD3 expression in bulky and non-bulky disease. CD3 expression was significantly lower in bulky disease patients when compared to non-bulky ones. CD3 showed a positive correlation with tryptase and MVD, while multiple regression analysis efficaciously predicted MVD depending on CD3 and tryptase as predictors, supporting a complex interplay between these cells in sustaining tumor angiogenesis in DLBCL patients. PMID:25957593

  17. 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. PMID:26729880

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

    PubMed Central

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

    2016-01-01

    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 cm2 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. PMID:26729880

  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. Sludge-grown algae for culturing aquatic organisms: Part I. Algal growth in sludge extracts

    NASA Astrophysics Data System (ADS)

    Hung, K. M.; Chiu, S. T.; Wong, M. H.

    1996-05-01

    This project is aimed at studying the feasibility of using sewage sludge to prepare culture media for microalgae ( Chlorella-HKBU) and the use of the sludge-grown algae as a feed for some aquatic organisms. Part I of the project included results on preparing sludge extracts and their use on algal culture. By comparing two culturing techniques, “aeration” and “shaking,” it was noted that both lag and log phases were shortened in the aeration system. A subsequent experiment noted that algal growth subject to aeration rates of 1.0 and 1.5 liters/min had similar lag and log phases. In addition, both aeration rates had a significantly higher ( P < 0.05) final cell density than that of 0.5 liters/min. A detailed study on the variation of growth conditions on the algal growth was done. The results indicated that pH values of all the cultures declined below 5 at day 12. The removal rates of ammonia N ranged from 62% to 70%. The sludge-grown algae contained a rather substantial amount of heavy metals (µg/g): Zn 289 581, Cu 443 682, Ni 310 963, Mn 96 126, Cr 25 118, and Fe 438 653. This implied that the rather high levels of heavy metals may impose adverse effects on higher trophic organisms.

  1. Ultra-high density standard cell library using multi-height cell structure

    NASA Astrophysics Data System (ADS)

    Baek, Sang-Hoon; Kim, Ha-Young; Lee, Young-Keun; Jin, Duck-Yang; Park, Se-Chang; Cho, Jun-Dong

    2008-12-01

    As the market size of mobile products is enlarged, low power and high density design in integrated chips are demanding. To meet these market demands, "ultra high density" (UHD) standard cell library becomes essential to further reduce the chip size. Furthermore, to enhance the density of standard cell library especially at 90nm and below, the conventional methods of reducing cell height is not sufficient to meet the density constraints. Motivated by the fact, in this paper, we devise a flexible design technique of UHD library with the multi-height cell structure. Each cell of conventional standard cell libraries with one-layer metal routing has the same cell height. However, multi-height cell library with two-layer metal routing has two types of cell structure: 1) Simple cells (e.g. inverter, nand, nor, etc.) are structured with single height; 2) Complex cells (e.g. flip-flop, latch, mux, etc.) are structured with double height. In this double height cell structure, Metal2 layer is used for power line. Therefore, Metal1 and G-ploy are routed vertically, gaining more Metal1 routing space, and thus we can attain more effective design for manufacturability (DFM). Also, by doing so, design time is reduced while achieving better layout efficiency. We tested logic circuits with 700,000 gates using 90nm technology to compare our new UHD library with existing high density library. Our experimental results show that each of 26 cells (frequently used) is shrunk by 14.29 ~ 26.98%. Furthermore, chip size is shrunk by 13.90 ~ 15.65% compared with high density library.

  2. 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. PMID:26358065

  3. Defect density and dielectric constant in perovskite solar cells

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    We report on measurement of dielectric constant, mid-gap defect density, Urbach energy of tail states in CH3NH3PbIxCl1-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 × 1011/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.

  4. 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.

  5. Sterol phylogenesis and algal evolution

    SciTech Connect

    Nes, W.D.; Norton, R.A.; Crumley, F.G. ); Madigan, S.J.; Katz, E.R. )

    1990-10-01

    The stereochemistry of several sterol precursors and end products synthesized by two fungal-like microorganisms Prototheca wickerhamii (I) and Dictyostelium discoideum (II) have been determined by chromatographic (TLC, GLC, and HPLC) and spectral (UV, MS, and {sup 1}H NMR) methods. From I and II the following sterols were isolated from the cells: cycloartenol, cyclolaudenol, 24(28)-methylenecy-cloartanol, ergosterol, protothecasterol, 4{alpha}-methylergostanol, 4{alpha}-methylclionastanol, clionastanol, 24{beta}-ethylcholesta-8,22-enol, and dictyosterol. In addition, the mechanism of C-24 methylation was investigated in both organisms by feeding to I (2-{sup 3}H)lanosterol, (2-{sup 3}H)cycloartenol, (24{sup 3}H)lanosterol, and (methyl-{sup 2}H{sub 3})methionine and by feeding to II (methyl-{sup 2}H{sub 3})methionine. The results demonstrate that the 24{beta} configuration is formed by different alkylation routes in I and II. The authors conclude that Prototheca is an apoplastic Chlorella (i.e., an alga) and that Dictyostelium as well as the other soil amoebae that synthesize cycloartenol evolved from algal rather than fungal ancestors.

  6. 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

  7. Density fingering in spatially modulated Hele-Shaw cells

    SciTech Connect

    Toth, Tamara; Horvath, Dezso; Toth, Agota

    2007-12-21

    Density fingering of the chlorite-tetrathionate reaction has been studied experimentally in a periodically heterogeneous Hele-Shaw cell where the heterogeneity is introduced in the form of spatial modulation of gap width along the front. Depending on the spatial wavelength, gap width, and chemical composition, three types of cellular structures have been observed. The initial evolution is characterized by dispersion curves, while the long time behavior is described by the change in the autocorrelation function of the front profile and in the mixing length of the patterns.

  8. 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.

  9. 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. PMID:26323272

  10. Probing topological relations between high-density and low-density regions of 2MASS with hexagon cells

    SciTech Connect

    Wu, Yongfeng; Xiao, Weike

    2014-02-01

    We introduced a new two-dimensional (2D) hexagon technique for probing the topological structure of the universe in which we mapped regions of the sky with high and low galaxy densities onto a 2D lattice of hexagonal unit cells. We defined filled cells as corresponding to high-density regions and empty cells as corresponding to low-density regions. The numbers of filled cells and empty cells were kept the same by controlling the size of the cells. By analyzing the six sides of each hexagon, we could obtain and compare the statistical topological properties of high-density and low-density regions of the universe in order to have a better understanding of the evolution of the universe. We applied this hexagonal method to Two Micron All Sky Survey data and discovered significant topological differences between the high-density and low-density regions. Both regions had significant (>5σ) topological shifts from both the binomial distribution and the random distribution.

  11. 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.

  12. 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. PMID:26061268

  13. Effects of Malaria Parasite Density on Blood Cell Parameters

    PubMed Central

    Kotepui, Manas; Piwkham, Duangjai; PhunPhuech, Bhukdee; Phiwklam, Nuoil; Chupeerach, Chaowanee; Duangmano, Suwit

    2015-01-01

    Changes in blood cell parameters are already a well-known feature of malarial infections. To add to this information, the objective of this study was to investigate the varying effects that different levels of parasite density have on blood cell parameters. Patients diagnosed with malaria at Phobphra Hospital, Tak Province, Thailand between January 1st 2009 and January 1st 2012 were recruited as subjects for data collection. Blood cell parameters of 2,024 malaria-infected patients were evaluated and statistically analyzed. Neutrophil and platelet counts were significantly higher, however, RBC count was significantly lower in patients with P. falciparum infection compared to those with P. vivax infection (p<0.0001). Leukocyte counts were also significantly higher in patients with high parasitemia compared to those with low and moderate parasitemia. In terms of differential leukocyte count, neutrophil count was significantly higher in patients with high parasitemia compared to those with low and moderate parasitemia (p<0.0001). On the other hand, both lymphocyte and monocyte counts were significantly lower in patients with high parasitemia (p<0.0001). RBC count and Hb concentration, as well as platelet count were also significantly reduced (p<0.05) and (p<0.0001), respectively. To summarize, patients infected with different malaria parasites exhibited important distinctive hematological parameters, with neutrophil and eosinophil counts being the two hematological parameters most affected. In addition, patients infected with different malarial densities also exhibited important changes in leukocyte count, platelet count and hemoglobin concentration during the infection. These findings offer the opportunity to recognize and diagnose malaria related anemia, help support the treatment thereof, as well as relieve symptoms of severe malaria in endemic regions. PMID:25807235

  14. Interactions of multiwalled carbon nanotubes with algal cells: quantification of association, visualization of uptake, and measurement of alterations in the composition of cells.

    PubMed

    Rhiem, Stefan; Riding, Matthew J; Baumgartner, Werner; Martin, Francis L; Semple, Kirk T; Jones, Kevin C; Schäffer, Andreas; Maes, Hanna M

    2015-01-01

    Carbon nanotubes (CNTs) are considered promising materials in nanotechnology. We quantified CNT accumulation by the alga Desmodesmus subspicatus. Cells were exposed to radiolabeled CNTs ((14)C-CNTs;1 mg/L) to determine uptake and association, as well as elimination and dissociation in clear media.Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) was used to detect effects of CNTs on algae. CNT-cell interactions were visualized by electron microscopy and related to alterations in their cell composition. A concentration factor of 5000 L/kg dry weight was calculated. Most of the material agglomerated around the cells, but single tubes were detected in the cytoplasm. Computational analyses of the ATR-FTIR data showed that CNT treated algae differed from controls at all sampling times.CNT exposure changed the biochemical composition of cells. The fact that CNTs are bioavailable for algae and that they influence the cell composition is important with regard to environmental risk assessment of this nanomaterial. PMID:25467692

  15. 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. PMID:23538998

  16. 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.

  17. Modulation of the cancer cell transcriptome by culture media formulations and cell density

    PubMed Central

    KIM, SEUNG WOOK; KIM, SUN-JIN; LANGLEY, ROBERT R.; FIDLER, ISAIAH J.

    2015-01-01

    We investigated how varying the composition of cell culture formulations and growing cancer cells at different densities might affect tumor cell genotype. Specifically, we compared gene expression profiles generated by human MDA-MB-231 breast cancer cells cultured in different media [minimum essential medium (MEM), Dulbecco’s modified Eagle’s medium (DMEM), or Roswell Park Memorial Institute (RPMI)-1640 medium] containing different concentrations of fetal bovine serum (FBS) or different sera (equine or bovine) that were grown at different cell densities. More than 2,000 genes were differentially modulated by at least a 2-fold difference when MDA-MB-231 cancer cells were 90% confluent and compared with cultures that were 50% confluent. Altering the concentration of serum produced an even more pronounced effect on MDA-MB-231 cancer cell gene expression in that 2,981 genes were differentially expressed in a comparison between cells cultured in 0.1% FBS and same cell density cultures that were maintained in 10% FBS. A comparison between MDA-MB-231 cancer cells that were 90% confluent in MEM, DMEM, or RPMI-1640 media, all containing 10% FBS, resulted in 8,925 differentially expressed genes. Moreover, one-quarter (25.6%) of genes from our genome-wide expression analysis were expressed at significantly different levels by cells grown in MEM, DMEM, or RPMI-1640 media. Genes associated with epithelial-mesenchymal transition (EMT) were among the genes that were differentially modulated by cells grown in different cell culture formulations and these genes were verified at the protein level. Collectively, these results underscore the importance of accurate reporting and maintenance of uniform culture conditions to ensure reproducible results. PMID:25776572

  18. Laboratory evaluation of six algal species for larval nutritional suitability of the pestiferous midge Glyptotendipes paripes (Diptera: Chironomidae).

    PubMed

    Frouz, Jan; Ali, Arshad; Lobinske, Richard J

    2004-12-01

    Glyptotendipes paripes Edwards midge larval growth, development, survival, emerging adult size, and food digestibility when provided with six species of algae as food were studied in the laboratory. For the study, eggs from G. paripes adults maintained in the laboratory were reared to the adult stage at 30 degrees C for 60 d on pure culture of each algal species at densities of 0.4, 0.1, and 0.02 mg of algae (fresh weight) per milliliter, as a sole food source. All larvae reared on Microcystis sp., Botryoccocus braunii, and Scenedesmus quadricauda died before completing development. The only larvae to complete development to adult were those reared on 0.4 mg/ml Lyngbia cf. aeruginosa (44.0 d), Anabaena flos-aquae (29.7 d), and Chlorella keslerii (44.8 d). No significant differences in body size of the adults achieving complete development on the three algal species were found. Algal digestion, measured by comparing amounts of live and dead algal cells in remains of cultures used for feeding and in larval excrement, revealed that >95% of all L. cf. aeruginosa, A. flos-aquae, and Microcystis sp. cells were digested; for C. keslerii, 13% of cells were digested, whereas little or no digestion of B. braunii and S. quadricauda was observed. To evaluate the effects of algal species on larval growth, laboratory-reared (on artificial food) late third/early fourth instars of G. paripes were fed individual algal species, and 10 d later, body mass changes were recorded and compared with nonfed larvae. Body mass of larvae reared on L. cf. aeruginosa and A. flos-aquae significantly increased, whereas those provided Microcystis sp. and the nonfed larvae showed significant body mass reductions. Overall, B. braunii and S. quadricauda were not suitable as larval food, probably due to their low digestibility, and Microcystis sp. because of its toxicity. This study identifies some algae that do and others that do not support G. paripes larval growth. The information is useful in

  19. 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. PMID:26263882

  20. Cell growth density modulates cancer cell vascular invasion via Hippo pathway activity and CXCR2 signaling.

    PubMed

    Sharif, G M; Schmidt, M O; Yi, C; Hu, Z; Haddad, B R; Glasgow, E; Riegel, A T; Wellstein, A

    2015-11-26

    Metastasis of cancer cells involves multiple steps, including their dissociation from the primary tumor and invasion through the endothelial cell barrier to enter the circulation and finding their way to distant organ sites where they extravasate and establish metastatic lesions. Deficient contact inhibition is a hallmark of invasive cancer cells, yet surprisingly the vascular invasiveness of commonly studied cancer cell lines is regulated by the density at which cells are propagated in culture. Cells grown at high density were less effective at invading an endothelial monolayer than cells grown at low density. This phenotypic difference was also observed in a zebrafish model of vascular invasion of cancer cells after injection into the yolk sac and extravasation of cancer cells into tissues from the vasculature. The vascular invasive phenotypes were reversible. A kinome-wide RNA interference screen was used to identify drivers of vascular invasion by panning small hairpin RNA (shRNA) library-transduced noninvasive cancer cell populations on endothelial monolayers. The selection of invasive subpopulations showed enrichment of shRNAs targeting the large tumor suppressor 1 (LATS1) kinase that inhibits the activity of the transcriptional coactivator yes-associated protein (YAP) in the Hippo pathway. Depletion of LATS1 from noninvasive cancer cells restored the invasive phenotype. Complementary to this, inhibition or depletion of YAP inhibited invasion in vitro and in vivo. The vascular invasive phenotype was associated with a YAP-dependent upregulation of the cytokines IL6, IL8 and C-X-C motif ligand 1, 2 and 3. Antibody blockade of cytokine receptors inhibited invasion and confirmed that they are rate-limiting drivers that promote cancer cell vascular invasiveness and could provide therapeutic targets. PMID:25772246

  1. Algal lectins as promising biomolecules for biomedical research.

    PubMed

    Singh, Ram Sarup; Thakur, Shivani Rani; Bansal, Parveen

    2015-02-01

    Lectins are natural bioactive ubiquitous proteins or glycoproteins of non-immune response that bind reversibly to glycans of glycoproteins, glycolipids and polysaccharides possessing at least one non-catalytic domain causing agglutination. Some of them consist of several carbohydrate-binding domains which endow them with the properties of cell agglutination or precipitation of glycoconjugates. Lectins are rampant in nature from plants, animals and microorganisms. Among microorganisms, algae are the potent source of lectins with unique properties specifically from red algae. The demand of peculiar and neoteric biologically active substances has intensified the developments on isolation and biomedical applications of new algal lectins. Comprehensively, algal lectins are used in biomedical research for antiviral, antinociceptive, anti-inflammatory, anti-tumor activities, etc. and in pharmaceutics for the fabrication of cost-effective protein expression systems and nutraceutics. In this review, an attempt has been made to collate the information on various biomedical applications of algal lectins. PMID:23855360

  2. Development and implementation of a perfusion-based high cell density cell banking process.

    PubMed

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

    2011-01-01

    A perfusion-based high cell density (HD) cell banking process has been developed that offers substantial advantages in time savings and simplification of upstream unit operations. HD cell banking provides the means to reduce the time required for culture inoculum expansion and scale-up by eliminating the need for multiple small to intermediate scale shake flask-based operations saving up to 9 days of operation during large-scale inoculum expansion. HD perfusion cultures were developed and optimized in a disposable Wave bioreactor system. Through optimization of perfusion rate, rocking speed and aeration rate, the perfusion system supported peak cell densities of >20 × 10(6) cells/mL while maintaining high cell viability (≥ 90%). The cells were frozen at HD (90-100 × 10(6) viable cells/mL) in 5-mL CryoTube vials. HD cell banks were demonstrated to enable direct inoculation of culture into a Wave bioreactor in the inoculum expansion train thus eliminating the need for intermediate shake flask expansion unit operations. The simplicity of the disposable perfusion system and high quality of the cell banks resulted in the successful implementation in a 2000 L scale manufacturing facility. PMID:21538974

  3. Effect of Initial Seeding Density on Human Umbilical Cord Mesenchymal Stromal Cells for Fibrocartilage Tissue Engineering

    PubMed Central

    Wang, Limin; Seshareddy, Kiran; Weiss, Mark L.

    2009-01-01

    Cells derived from Wharton's jelly from human umbilical cords (called umbilical cord mesenchymal stromal cells herein) are a novel cell source for musculoskeletal tissue engineering. In this study, we examined the effects of different seeding densities on seeding efficiency, cell proliferation, biosynthesis, mechanical integrity, and chondrogenic differentiation. Cells were seeded on non-woven polyglycolic acid (PGA) meshes in an orbital shaker at densities of 5, 25, or 50 million cells/mL and then statically cultured for 4 weeks in chondrogenic medium. At week 0, initial seeding density did not affect seeding efficiency. Throughout the 4-week culture period, absolute cell numbers of the 25 and 50 million-cells/mL (higher density) groups were significantly larger than in the 5 million-cells/mL (lower density) group. The presence of collagen types I and II and aggrecan was confirmed using immunohistochemical staining. Glycosaminoglycan and collagen contents per construct in the higher-density groups were significantly greater than in the lower-density group. Constructs in the high-density groups maintained their mechanical integrity, which was confirmed using unconfined compression testing. In conclusion, human umbilical cord cells demonstrated the potential for chondrogenic differentiation in three-dimensional tissue engineering, and higher seeding densities better promoted biosynthesis and mechanical integrity, and thus a seeding density of at least 25 million cells/mL is recommended for fibrocartilage tissue engineering with umbilical cord mesenchymal stromal cells. PMID:18759671

  4. 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.

  5. 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

  6. Cell density modulates growth, extracellular matrix, and protein synthesis of cultured rat mesangial cells.

    PubMed

    Wolthuis, A; Boes, A; Grond, J

    1993-10-01

    Mesangial cell (MC) hyperplasia and accumulation of extracellular matrix are hallmarks of chronic glomerular disease. The present in vitro study examined the effects of cell density on growth, extracellular matrix formation, and protein synthesis of cultured rat MCs. A negative linear relationship was found between initial plating density and DNA synthesis per cell after 24 hours incubation in medium with 10% fetal calf serum (range: 1 x 10(3) to 7 x 10(5) MCs/2cm2, r = 0.996, P < 0.001). Enzyme-linked immunosorbent assay of the amount of fibronectin in the conditioned medium after 72 hours showed a negative relationship with increasing cell density. In contrast, the amount of cell-associated fibronectin increased to maximal values in confluent cultures, and no further increase was seen at supraconfluency. The relative collagen synthesis in the conditioned medium and cell layer--assessed by collagenase digestion after 5 hours [3H]proline pulse labeling--showed a similar pattern. Secreted collagen decreased with increasing cell density from 3.4% to 0.2% of total protein synthesis. In contrast, cell-associated collagen increased from 1.1% to 11.8% of newly synthesized protein until confluency followed by a decrease to 4.2% at supraconfluency. Specific immunoprecipitation of collagen types I, III, and IV revealed a significant (twofold) increase in collagen I synthesis per cell at confluency. Collagen III and IV synthesis was not affected by cell density. Specific protein expression in both the medium and cell layer were analyzed by two-dimensional polyacrylamide gel electrophoresis (150 to 20 kd, pI 5.0 to 7.0) after 20 hours steady-state metabolic labeling with [35S]methionine. Supraconfluent MCs displayed overexpression of 10, underexpression of four, new expression of five, and changed mobility of three different intracellular proteins. Of interest was the overexpression of two proteins (89 kd, pI 5.31 and 72 kd, pI 5.32) that were identified by immunoblotting as

  7. 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.

  8. 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

  9. Itinerary of high density lipoproteins in endothelial cells.

    PubMed

    Perisa, Damir; Rohrer, Lucia; Kaech, Andres; von Eckardstein, Arnold

    2016-02-01

    High density lipoprotein (HDL) and its main protein component apolipoprotein A-I (ApoA-I) have multiple anti-atherogenic functions. Some of them are exerted within the vessel wall, so that HDL needs to pass the endothelial barrier. To elucidate their itinerary through endothelial cells (ECs), we labelled ApoA-I and HDL either fluorescently or with 1.4 nm nanogold and investigated their cellular localization by using immunofluorescent microscopy (IFM) and electron microscopy (EM). HDL as well as ApoA-I is taken up by ECs into the same route of intracellular trafficking. Time kinetics and pulse chase experiments revealed that HDL is trafficked through different vesicles. HDL partially co-localized with LDL, albumin, and transferrin. HDL did not co-localize with clathrin and caveolin-1. Fluorescent HDL was recovered at small proportions in early endosomes and endosome to trans-golgi network vesicles but not at all in recycling endosomes, in late endosomes or lysosomes. EM identified HDL mainly in large filled vesicles which however upon IFM did not colocalize with markers of multivesicular bodies or autophagosomes. The uptake or cellular distribution of HDL was altered upon pharmacological interference with cytochalasine D, colchicine and dynasore. Blockage of fluid phase uptake with Amiloride or EIPA did not reduce the uptake of HDL. Neither did we observe any co-localization of HDL with dextran as the marker of fluid phase uptake. In conclusion, HDL and ApoA-I are internalized and trafficked by endothelial cells through a non-classical endocytic route. PMID:26577406

  10. 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. PMID:23116542

  11. An algal removal using a combination of flocculation and flotation processes.

    PubMed

    Phoochinda, W; White, D A; Briscoe, B J

    2004-12-01

    The paper describes certain facets of the removal of the algae (Scenedesmus quadricauda) from water, using a froth flotation separation method, in conjunction with two types of surfactants, (cetyltrimethylammonium bromide) CTAB and (sodium dodecylsulfate) SDS. A 90% algal removal efficiency was achieved when 100 mg l(-1) of CTAB was used whereas for the SDS solutions, the same concentration gave, by comparison, a very poor algal removal efficiency. An addition of 1 mg l(-1) of a commercial cationic polyelectrolyte, which was the optimal concentration as was evident from the zeta potential and the particle size distribution measurements, prior to the SDS addition resulted in a formation of algal flocs and consequently a substantial improvement in the extent of the algal removal. A 50 mg l(-1) solution of SDS was found to be the optimal concentration to completely remove these algal flocs from water. The amount of water removed along with the algal flocs, produced using 1 mg l(-1) of the commercial polyelectrolyte and subsequently removed using SDS, was comparatively lower than that removed with the algal cells when CTAB was used as the 'collector'. It was generally found, in this study, that an addition of the polyelectrolyte improved the removal efficiencies and the rate of separation and also decreased the amount of the associated water removed along with the algal sludge. PMID:15691199

  12. 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. PMID:27008510

  13. 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.

  14. Use of the mitochondria toxicity assay for quantifying the viable cell density of microencapsulated jurkat cells.

    PubMed

    Werner, M; Biss, K; Jérôme, V; Hilbrig, F; Freitag, R; Zambrano, K; Hübner, H; Buchholz, R; Mahou, R; Wandrey, C

    2013-01-01

    The mitochondria toxicity assay (MTT assay) is an established method for monitoring cell viability based on mitochondrial activity. Here the MTT assay is proposed for the in situ quantification of the living cell density of microencapsulated Jurkat cells. Three systems were used to encapsulate the cells, namely a membrane consisting of an interpenetrating polyelectrolyte network of sodium cellulose sulphate/poly(diallyldimethylammonium chloride) (NaCS/PDADMAC), a calcium alginate hydrogel covered with poly(L-lysine) (Ca-alg-PLL), and a novel calcium alginate-poly(ethylene glycol) hybrid material (Ca-alg-PEG). MTT results were correlated to data obtained by the trypan blue exclusion assay after release of the cells from the NaCS/PDADMAC and Ca-alg-PLL capsules, while a resazurin-based assay was used for comparison in case of the Ca-alg-PEG material. Analysis by MTT assay allows quick and reliable determination of viable cell densities of encapsulated cells independent of the capsule material. The assay is highly reproducible with inter-assay relative standard deviations below 10%. PMID:23636962

  15. 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.

  16. 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...

  17. Daily variation in radiosensitivity of circulating blood cells and bone marrow cell density in mice

    SciTech Connect

    Tabatabai, R.N.

    1984-01-01

    Mice on a 12/12 light/dark cycle were bled during a twenty-four hour period each week for eight weeks to establish daily values of circulating blood cells. No significant daily variation was found in total red blood cells, hematocrit, or percentage of reticulocytes. A significant (P < 0.001) daily variation was found in total white blood cells, with the minimum occurring at 8 PM and the maximum occurring during the daylight hours from 8 a.m. to 2 p.m. Mice were then exposed to 0 R, 20 R, 50 R, or 100 R of x-radiation to determine what dose significantly reduces the total white cell count in circulating blood. It was found that 100 R significantly (P < .05) reduces the total white cell count over a four week period post-exposure. To determine if circulating blood cells and bone marrow cells show a diurnal radiosensitivity, mice were exposed to 100 R or 200 R of x-radiation at noon or midnight. Hematocrits, reticulocyte and white blood cell counts, daily white blood cell rhythm, and bone marrow cell density indicate that these mice were more radiosensitive at night.

  18. 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. PMID:23499181

  19. 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.

  20. 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.

  1. 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

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

    PubMed

    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

  3. High-density lipoprotein, mitochondrial dysfunction and cell survival mechanisms.

    PubMed

    White, C Roger; Giordano, Samantha; Anantharamaiah, G M

    2016-09-01

    Ischemic injury is associated with acute myocardial infarction, percutaneous coronary intervention, coronary artery bypass grafting and open heart surgery. The timely re-establishment of blood flow is critical in order to minimize cardiac complications. Reperfusion after a prolonged ischemic period, however, can induce severe cardiomyocyte dysfunction with mitochondria serving as a major target of ischemia/reperfusion (I/R) injury. An increase in the formation of reactive oxygen species (ROS) induces damage to mitochondrial respiratory complexes leading to uncoupling of oxidative phosphorylation. Mitochondrial membrane perturbations also contribute to calcium overload, opening of the mitochondrial permeability transition pore (mPTP) and the release of apoptotic mediators into the cytoplasm. Clinical and experimental studies show that ischemic preconditioning (ICPRE) and postconditioning (ICPOST) attenuate mitochondrial injury and improve cardiac function in the context of I/R injury. This is achieved by the activation of two principal cell survival cascades: 1) the Reperfusion Injury Salvage Kinase (RISK) pathway; and 2) the Survivor Activating Factor Enhancement (SAFE) pathway. Recent data suggest that high density lipoprotein (HDL) mimics the effects of conditioning protocols and attenuates myocardial I/R injury via activation of the RISK and SAFE signaling cascades. In this review, we discuss the roles of apolipoproteinA-I (apoA-I), the major protein constituent of HDL, and sphingosine 1-phosphate (S1P), a lysosphingolipid associated with small, dense HDL particles as mediators of cardiomyocyte survival. Both apoA-I and S1P exert an infarct-sparing effect by preventing ROS-dependent injury and inhibiting the opening of the mPTP. PMID:27150975

  4. 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. PMID:10680014

  5. 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.

  6. 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.

  7. 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.

  8. 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. PMID:10899706

  9. Selective algicidal action of peptides against harmful algal bloom species.

    PubMed

    Park, Seong-Cheol; Lee, Jong-Kook; Kim, Si Wouk; Park, Yoonkyung

    2011-01-01

    Recently, harmful algal bloom (HAB), also termed "red tide", has been recognized as a serious problem in marine environments according to climate changes worldwide. Many novel materials or methods to prevent HAB have not yet been employed except for clay dispersion, in which can the resulting sedimentation on the seafloor can also cause alteration in marine ecology or secondary environmental pollution. In the current study, we investigated that antimicrobial peptide have a potential in controlling HAB without cytotoxicity to harmless marine organisms. Here, antimicrobial peptides are proposed as new algicidal compounds in combating HAB cells. HPA3 and HPA3NT3 peptides which exert potent antimicrobial activity via pore forming action in plasma membrane showed that HPA3NT3 reduced the motility of algal cells, disrupted their plasma membrane, and induced the efflux of intracellular components. Against raphidoflagellate such as Heterosigma akashiwo, Chattonella sp., and C. marina, it displayed a rapid lysing action in cell membranes at 1~4 µM within 2 min. Comparatively, its lysing effects occurred at 8 µM within 1 h in dinoflagellate such as Cochlodium polykrikoides, Prorocentrum micans, and P. minimum. Moreover, its lysing action induced the lysis of chloroplasts and loss of chlorophyll a. In the contrary, this peptide was not effective against Skeletonema costatum, harmless algal cell, even at 256 µM, moreover, it killed only H. akashiwo or C. marina in co-cultivation with S. costatum, indicating to its selective algicidal activity between harmful and harmless algal cells. The peptide was non-hemolytic against red blood cells of Sebastes schlegeli, the black rockfish, at 120 µM. HAB cells were quickly and selectively lysed following treatment of antimicrobial peptides without cytotoxicity to harmless marine organisms. Thus, the antibiotic peptides examined in our study appear to have much potential in effectively controlling HAB with minimal impact on marine

  10. 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.

  11. Influence of plating density on individual cell growth, cell division and differentiation of neonatal rat heart primary cultures.

    PubMed

    Millart, H; Seraydarian, M W

    1986-01-01

    The influence of plating cell density of an originally enriched myocardial cell population has been studied in neonatal rat heart cells in culture. Low density (LDM) is defined as a density (24 h after plating) of 209 +/- 44 cells/mm2 (mean +/- SEM) and is compared with high density (HDM), 419 +/- 67 cells/mm2. Cell growth is evaluated by the total cell number, the percentage of myocardial cells (M) in culture (PAS method) and the protein content per cell. Some differentiation parameters such as beating rates, glycogen concentration, enzymatic activities (cytochrome C oxidase and glycogen phosphorylase) are studied with time in culture (48, 96 and 192 hr). High density was designed to yield a complete confluency of the cells within 24 hr after plating and to minimize cell division of the non-muscle cells (F). At high density, cell division of F cells is effectively limited, thus leading to a more stable model regarding the cell density per plate and the percentage of M cells: 85.7 +/- 4% and 33.4 +/- 6% in LDM cultures compared with 86.5 +/- 4.7% and 51.7 +/- 9.8% in HDM cultures at 24 and 192 hr (mean +/- SEM). Heart cells increase similarly in size with age in culture in both groups. In HDM cultures the spontaneous contractions begin sooner (24 hr) than in LDM cultures and are more rapidly synchronized. The beating rate is higher in HDM cultures between 48 and 96 hr; however, after this time it falls in HDM and does not fall in LDM. Thus the overgrowth of muscle cells by non-muscle cells is not responsible for loss of beating with time in culture but more likely high density could be a limiting factor for isotonic contraction. There is more glycogen per myocyte in LDM than in HDM cultures. The cell density influences the enzymatic activities of cytochrome C oxidase and glycogen phosphorylase. The cytochrome oxidase activity is higher in HDM cultures than in LDM cultures at 96 hr whereas glycogen phosphorylase activity is higher in LDM cultures at time 96 and 192

  12. 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.

  13. [Changes of algal communities in water body with different proportions of nitrogen and phosphorus].

    PubMed

    Sun, Ling; Jin, Xiangcan; Zhong, Yuan; Zhang, Dongmei; Zhu, Lin; Dai, Shugui; Zhuang, Yuanyi

    2006-07-01

    A simulation test was conducted in aquaria to study the responses of algal communities to different N/P ratios in urban water body. The water sample was taken from a small artificial lake in Tianjin, and its initial N/P ratio was adjusted to 0. 5:1,7.2:1, 25:1 and 50:1, respectively. The results showed that in high N/P ratio groups, the numbers of Chlorophyta species decreased, while those of Cyanophyta species didn' t change very much. The numbers of these two species were both decreased in low N/P ratio group. Algal biomass, cell density and chlorophyll a content in medium and high N groups were higher than those in control and high P groups. The mean value of chlorophyll a reached the highest (69.7 microg x L(-1)) in high N group, and was 54.3, 30.3 and 29.7 microg x L(-1) in medium N, control, and high P groups, respectively. At the mid-late stages of culture, green algae Dictyosphaerium pulchellum was dominant in high P group, while blue algae Phormidium tenue, P. corium, Lyngbya limnetica and Microcystis aeruginosa were dominated in high N/P ratio groups. Control group had the highest species richness, while medium and high N groups had the highest and lowest ecological species dominance, respectively. PMID:17044495

  14. 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.

  15. 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.

  16. 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.

  17. Measuring single cell mass, volume, and density with dual suspended microchannel resonators.

    PubMed

    Bryan, Andrea K; Hecht, Vivian C; Shen, Wenjiang; Payer, Kristofor; Grover, William H; Manalis, Scott R

    2014-02-01

    Cell size, measured as either volume or mass, is a fundamental indicator of cell state. Far more tightly regulated than size is density, the ratio between mass and volume, which can be used to distinguish between cell populations even when volume and mass appear to remain constant. Here we expand upon a previous method for measuring cell density involving a suspended microchannel resonator (SMR). We introduce a new device, the dual SMR, as a high-precision instrument for measuring single-cell mass, volume, and density using two resonators connected by a serpentine fluidic channel. The dual SMR designs considered herein demonstrate the critical role of channel geometry in ensuring proper mixing and damping of pressure fluctuations in microfluidic systems designed for precision measurement. We use the dual SMR to compare the physical properties of two well-known cancer cell lines: human lung cancer cell H1650 and mouse lymphoblastic leukemia cell line L1210. PMID:24296901

  18. Evaluating the B-cell density with various activation functions using White Noise Path Integral Approach

    NASA Astrophysics Data System (ADS)

    Aban, C. J. G.; Bacolod, R. O.; Confesor, M. N. P.

    2015-06-01

    A The White Noise Path Integral Approach is used in evaluating the B-cell density or the number of B-cell per unit volume for a basic type of immune system response based on the modeling done by Perelson and Wiegel. From the scaling principles of Perelson [1], the B- cell density is obtained where antigens and antibodies mutates and activation function f(|S-SA|) is defined describing the interaction between a specific antigen and a B-cell. If the activation function f(|S-SA|) is held constant, the major form of the B-cell density evaluated using white noise analysis is similar to the form of the B-cell density obtained by Perelson and Wiegel using a differential approach.A piecewise linear functionis also used to describe the activation f(|S-SA|). If f(|S-SA|) is zero, the density decreases exponentially. If f(|S-SA|) = S-SA-SB, the B- cell density increases exponentially until it reaches a certain maximum value. For f(|S-SA|) = 2SA-SB-S, the behavior of B-cell density is oscillating and remains to be in small values.

  19. Algal biosensor array on a single electrode.

    PubMed

    Tatsuma, Tetsu; Yoshida, Yutaka; Shitanda, Isao; Notsu, Hideo

    2009-02-01

    An algal array was prepared on a single transparent electrode, and photosynthetic activity of each algal channel and its inhibition by a toxin were monitored with a single-channel potentiostat by successive light irradiation with a LED array. PMID:19173040

  20. TEXAS HARMFUL ALGAL BLOOM COORDINATION MX964014

    EPA Science Inventory

    Harmful algal blooms (HAB) are an expanding problem in coastal Texas. Nearly � of the known harmful algal blooms along the Texas coast have occurred in the past ten years and have led to significant resource and tourism losses. For example, there are at least two types of toxic...

  1. 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.

  2. Flagellum Density Regulates Proteus mirabilis Swarmer Cell Motility in Viscous Environments

    PubMed Central

    Tuson, Hannah H.; Copeland, Matthew F.; Carey, Sonia; Sacotte, Ryan

    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 FlhD4C2, 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. PMID:23144253

  3. Simulating pH effects in an algal-growth hydrodynamics model(1).

    PubMed

    James, Scott C; Janardhanam, Vijayasarathi; Hanson, David T

    2013-06-01

    Models and numerical simulations are relatively inexpensive tools that can be used to enhance economic competitiveness through operation and system optimization to minimize energy and resource consumption, while maximizing algal oil yield. This work uses modified versions of the U.S. Environmental Protection Agency's Environmental Fluid Dynamics Code (EFDC) in conjunction with the U.S. Army Corp of Engineers' water-quality code (CE-QUAL) to simulate flow hydrodynamics coupled to algal growth kinetics. The model allows the flexibility of manipulating a host of variables associated with algal growth such as temperature, light intensity, and nutrient availability. pH of the medium is a newly added operational parameter governing algal growth that affects algal photosynthesis, differential availability of inorganic forms of carbon, enzyme activity in algae cell walls, and oil production rates. A single-layer algal-growth/hydrodynamic model without pH limitation was verified by comparing solution curves of algal biomass and phosphorus concentrations to an analytical solution. Media pH, now included in the model as a growth-limiting factor, can be entered as a measured value or calculated based on CO2 concentrations. Upon adding the ability to limit growth due to pH, physically reasonable results have been obtained from the model both with and without pH limitation. When the model was used to simulate algal growth from a pond experiment in the greenhouse, a least-squares fitting technique yielded a maximum algal production (subsequently modulated by limitation factors) of 1.05 d(-1) . Overall, the measured and simulated biomass concentrations in the greenhouse pond were in close agreement. PMID:27007048

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

    NASA Astrophysics Data System (ADS)

    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.

  5. 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. PMID:23886651

  6. Mathematical Modeling Reveals That Changes to Local Cell Density Dynamically Modulate Baseline Variations in Cell Growth and Drug Response.

    PubMed

    Greene, James M; Levy, Doron; Herrada, Sylvia P; Gottesman, Michael M; Lavi, Orit

    2016-05-15

    Cell-to-cell variations contribute to drug resistance with consequent therapy failure in cancer. Experimental techniques have been developed to monitor tumor heterogeneity, but estimates of cell-to-cell variation typically fail to account for the expected spatiotemporal variations during the cell growth process. To fully capture the extent of such dynamic variations, we developed a mechanistic mathematical model supported by in vitro experiments with an ovarian cancer cell line. We introduce the notion of dynamic baseline cell-to-cell variation, showing how the emerging spatiotemporal heterogeneity of one cell population can be attributed to differences in local cell density and cell cycle. Manipulation of the geometric arrangement and spatial density of cancer cells revealed that given a fixed global cell density, significant differences in growth, proliferation, and paclitaxel-induced apoptosis rates were observed based solely on cell movement and local conditions. We conclude that any statistical estimate of changes in the level of heterogeneity should be integrated with the dynamics and spatial effects of the baseline system. This approach incorporates experimental and theoretical methods to systematically analyze biologic phenomena and merits consideration as an underlying reference model for cell biology studies that investigate dynamic processes affecting cancer cell behavior. Cancer Res; 76(10); 2882-90. ©2016 AACR. PMID:26933088

  7. 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.

  8. 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. PMID:26995605

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

    PubMed

    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

  10. 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

  11. A model for cell density effect on stress fiber alignment and collective directional migration

    NASA Astrophysics Data System (ADS)

    Abeddoust, Mohammad; Shamloo, Amir

    2015-12-01

    In this study, numerical simulation of collective cell migration is presented in order to mimic the group migration of endothelial cells subjected to the concentration gradients of a biochemical factor. The developed 2D model incorporates basic elements of the cell, including both the cell membrane and the cell cytoskeleton, based on a viscoelastic cell mechanic model. Various cell processes—including cell random walk, cell-cell interactions, cell chemotaxis, and cellular cytoskeleton rearrangements—are considered and analyzed in our developed model. After validating the model by using available experimental data, the model is used to investigate various important parameters during collective cell chemotaxis, such as cell density, cytoskeleton organization, stress fiber reorientations, and intracellular forces. The results suggest that increasing the cell density causes the cell-cell interactions to affect the orientation of stress fibers throughout the cytoskeleton and makes the stress fibers more aligned in the direction of the imposed concentration gradient. This improved alignment of the stress fibers correlates with the intensification of the intracellular forces transferred in the gradient direction; this improves the cell group migration. Comparison of the obtained results with available experimental observations of collective chemotaxis of endothelial cells shows an interesting agreement.

  12. 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

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

    SciTech Connect

    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.

  14. Long term phytoplankton monitoring, including harmful algal blooms, in the Bay of Fundy, eastern Canada

    NASA Astrophysics Data System (ADS)

    Martin, J. L.; Hanke, A. R.; LeGresley, M. M.

    2009-01-01

    A monitoring program was initiated in May 1987 to study phytoplankton populations in the Bay of Fundy, southwest New Brunswick, eastern Canada. Samples are collected for phytoplankton distribution and abundance at five locations in the Bay of Fundy. Other parameters measured include plant nutrients (ammonia, nitrite, nitrate, phosphate and silicate), Secchi depth, and depth profiles for fluorescence, oxygen, temperature and salinity. Alexandrium fundyense abundance from the 5 sites and between years is compared to physical and chemical properties of seawater using principle component analyses (PCA) to identify factors showing the greatest amount of variance in temporal and spatial distribution patterns. Analysis of A. fundyense abundance over the 19-year period 1987-2005 indicates that cell abundance from one year does not reflect the following year's phytoplankton concentration, and nitrate values and cell densities appear to have a negative relationship. A further comparison between the 2 years 2004 and 2005 (years with very different intensities of A. fundyense maximum cell concentrations) further supported these findings. Preliminary analyses indicate that many species abundances and intensities appear to be more climate or weather related than nutrient flux related. Examination of relationships between harmful algal bloom (HAB) cell density, nutrients and environmental variables indicates that there is no evidence that HABs are linked to eutrophication processes at the temporal and spatial scales of the study.

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

    PubMed Central

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

    2016-01-01

    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. PMID:26832069

  16. 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.

  17. 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.

  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. 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. PMID:22983032

  20. 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

  1. 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

  2. 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

  3. Efficient production of propionic acid through high density culture with recycling cells of Propionibacterium acidipropionici.

    PubMed

    Liu, Zhen; Ge, Yongsheng; Xu, Jing; Gao, Chao; Ma, Cuiqing; Xu, Ping

    2016-09-01

    The aim of this study was to explore propionic acid production via high density culture of Propionibacterium acidipropionici and recycling of cells. Results showed that final cells of P. acidipropionici from high density culture still had high metabolic activity for reuse. Using our process, 75.9gl(-1) propionic acid was produced, which was 1.84-fold of that in fed-batch fermentation with low cell density (41.2gl(-1)); the corresponding productivity was 100.0% higher than that in fed-batch fermentation with low cell density (0.16gl(-1)h(-1)). This bioprocess may have potential for the industrial production of propionic acid. PMID:27318164

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

    SciTech Connect

    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.

  5. 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.

  6. 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.

  7. 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. PMID:26211654

  8. 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. PMID:25189508

  9. 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. PMID:24161650

  10. 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

  11. 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.

  12. 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.

  13. The Relative Importance of Topography and RGD Ligand Density for Endothelial Cell Adhesion

    PubMed Central

    Le Saux, Guillaume; Magenau, Astrid; Böcking, Till; Gaus, Katharina; Gooding, J. Justin

    2011-01-01

    The morphology and function of endothelial cells depends on the physical and chemical characteristics of the extracellular environment. Here, we designed silicon surfaces on which topographical features and surface densities of the integrin binding peptide arginine-glycine-aspartic acid (RGD) could be independently controlled. We used these surfaces to investigate the relative importance of the surface chemistry of ligand presentation versus surface topography in endothelial cell adhesion. We compared cell adhesion, spreading and migration on surfaces with nano- to micro-scaled pyramids and average densities of 6×102–6×1011 RGD/mm2. We found that fewer cells adhered onto rough than flat surfaces and that the optimal average RGD density for cell adhesion was 6×105 RGD/mm2 on flat surfaces and substrata with nano-scaled roughness. Only on surfaces with micro-scaled pyramids did the topography hinder cell migration and a lower average RGD density was optimal for adhesion. In contrast, cell spreading was greatest on surfaces with 6×108 RGD/mm2 irrespectively of presence of feature and their size. In summary, our data suggest that the size of pyramids predominately control the number of endothelial cells that adhere to the substratum but the average RGD density governs the degree of cell spreading and length of focal adhesion within adherent cells. The data points towards a two-step model of cell adhesion: the initial contact of cells with a substratum may be guided by the topography while the engagement of cell surface receptors is predominately controlled by the surface chemistry. PMID:21779342

  14. 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.

  15. 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.

  16. Endothelial cell perturbation and low-density lipoprotein. Quantitative autoradiography

    SciTech Connect

    Morrel, E.M.; Holland, J.A.; Pritchard, K.A.; Colton, C.K.; Stemerman, M.B.

    1987-01-01

    The focal entry and accumulation of LDL within the arterial wall of the normal animal may represent an early stage in the development of the atherosclerotic plaque. Concentrations of LDL 10 to 100 times normal medial concentrations might be difficult to clear from the arterial wall, permitting accumulation of lipid. Elevated LDL concentrations, in proximity to smooth muscle cells, appear to stimulate SMC proliferation. High LDL concentrations might also enhance mononuclear cell adhesion to endothelium. Since LDL has a high affinity for heparin and heparin for growth factors, LDL accumulation may be a mechanism for the concentration of such materials in the intima. The observation of markedly enhanced macromolecular permeability foci could be related to several potential mechanisms of initiation of atherosclerosis. This observation is of particular note when the focal occurrence of atherosclerosis is considered. Although atherosclerosis is seen as a generalized thickening of the intima, it is the focal narrowing of the lumen that is often responsible for the stenosis which produces symptoms such as angina or myocardial infarction.

  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. Strategies for optimizing algal biology for enhanced biomass production

    DOE PAGESBeta

    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

  19. 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.

  20. The impact of algal properties and pre-oxidation on solid-liquid separation of algae.

    PubMed

    Henderson, Rita; Parsons, Simon A; Jefferson, Bruce

    2008-04-01

    Algae are traditionally classified according to biological descriptors which do not give information on surface characteristics that are important with respect to removal by water treatment processes. This review examines the character of freshwater algal populations from a water treatment perspective and evaluates the impact of their varying properties and the use of pre-oxidation on their removal by solid-liquid separation processes.. The characteristics shown to impact on treatment were morphology, motility, surface charge, cell density and the extracellular organic matter (EOM) composition and concentration. With the exception of density, these are not phyla specific. It was also shown that dissolved air flotation (DAF) was the most robust clarification method, where up to 99.8% removal was achieved compared to 94% for sedimentation when using metal coagulants. However, successful clarification relied heavily on the optimisation of preceding coagulation and flocculation and coagulant demand was important in this respect. Comparison of all available data reveals a relationship between cell surface area and coagulant demand. It is thus suggested that cell surface area would provide a basis for regrouping algae such that the classification is informative with respect to water treatment. However, the absolute coagulant demand is a result of both surface area and EOM influences. The latter are relatively poorly understood in comparison to natural organic matter (NOM) systems and this remains a limit in current knowledge. PMID:18261761

  1. 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 ...

  2. Eukaryotic algal phytochromes span the visible spectrum.

    PubMed

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

    2014-03-11

    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

  3. 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. PMID:26705954

  4. 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. PMID:23866138

  5. 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. PMID:25277172

  6. Independence of buoyant cell density and growth rate in Escherichia coli

    SciTech Connect

    Kubitchek, H.E.; Baldwin, W.W.; Schroeter, S.J.; Graetzer, R.

    1984-04-01

    The relationship between growth rate and buoyant density was determined for cells from exponential-phase cultures of Escherichia coli B/r NC32 by equilibrium centrifugation in Percoll gradients at growth rates ranging from 0.15 to 2.3 doublings per h. The mean buoyant density did not change significantly with growth rate in any of three sets of experiments in which different gradient conditions were used. In addition, when cultures were allowed to enter the stationary phase of growth, mean cell volumes and buoyant densities usually remained unchanged for extended periods. These and earlier results support the existence of a highly regulated, discrete state of buoyant density during steady-state growth of E. coli and other cells that divide by equatorial fission. 11 references, 3 figures.

  7. 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}.

  8. Is there any role of mast cell density and microvessel density in cervical squamous cell carcinoma? A histologic study with special reference to CD-34 immunomarker staining

    PubMed Central

    Mondal, Santosh Kumar; Dasgupta, Senjuti; Mandal, Palash Kumar; Chatterjee, Shankha; Chakraborty, Debdutta

    2014-01-01

    Background: Mast cells are involved in induction of angiogenesis in the early-stages of tumor development and in modulating blood vessel growth in the later stages of tumor progression. Aims and Objectives: This study was carried out to evaluate the association between mast cell density (MCD) and microvessel density (MVD) in carcinoma in situ (CIS), microinvasive carcinoma (CA) and invasive squamous cell CA of cervix. Materials and Methods: Six cases of CIS, four cases of microinvasive CA and 38 cases of invasive CA were studied over a period of 2 years from August, 2011 to June, 2013. Ten control samples were included in the study. Routine histologic examination was done. Toluidine blue stain was used for MCD determination. Immunohistochemical analysis with CD-34 was done for assessing MVD. Student's t-test was used to calculate the statistical significance of MCD and MVD. Results: Both MCD and MVD increased from normal samples through CIS to invasive cervical CA. In the four cases of microinvasive CA, the MCD and MVD were more than that of the control samples, but less than that of the six cases of CIS. Conclusion: There is a correlation between mast cell accumulation and angiogenesis in CIS, microinvasive CA and invasive cervical squamous cell CA. MCD and MVD in invasive CA exceed those in CIS and microinvasive CA. It gives us an opportunity to postulate that therapeutic strategies against mast cell mediators and angiogenesis may be of benefit in patients of early-stage cervical CA. PMID:25197180

  9. 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.

  10. An algal solution to large scale wastewater amelioration

    SciTech Connect

    Adey, W.H.

    1995-06-01

    Wastewater nutrients can be lowered to oligotrophic levels through uptake by algal biomass, while photosynthetic oxygen removes bacterial BOD, and oxygen-based ions, with UV application, can break down xenobiotic organic compounds. Algae also uptake heavy metals in cell walls, and the high pH from CO{sub 25} removal precipitates metals, earth metals and phosphorus. Algal biomass produced from many wastewaters has valuable commercial applications. Algal Turf Scrubbing (ATS) was developed as a tool to control water quality in ecosystem models, often at oligotrophic levels. ATS has routinely achieved biomass production (and water amelioration capability) of over 50 g (dry mass) m{sup -2} day{sup -1} in secondary sewage. Engineering innovations, with mechanized harvest, have brought ATS to large scale with a pilot sewage plant in central California. This is a low cost, modular unit, at 1000 cubic meters per day, and plans are underway to expand to city capacity for Tertiary-Quinary water recovery. A wide variety of wastewater applications, from agricultural, to aquacultural to industrial will be discussed.

  11. 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. PMID:24920320

  12. 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. PMID:25105247

  13. Factors regulating viable cell density in the intervertebral disc: blood supply in relation to disc height

    PubMed Central

    Boubriak, Olga A; Watson, Natasha; Sivan, Sarit S; Stubbens, Naomi; Urban, Jill P G

    2013-01-01

    The intervertebral disc is an avascular tissue, maintained by a small population of cells that obtain nutrients mainly by diffusion from capillaries at the disc–vertebral body interface. Loss of this nutrient supply is thought to lead to disc degeneration, but how nutrient supply influences viable cell density is unclear. We investigated two factors that influence nutrient delivery to disc cells and hence cell viability: disc height and blood supply. We used bovine caudal discs as our model as these show a gradation in disc height. We found that although disc height varied twofold from the largest to the smallest disc studied, it had no significant effect on cell density, unlike the situation found in articular cartilage. The density of blood vessels supplying the discs was markedly greater for the largest disc than the smallest disc, as was the density of pores allowing capillary penetration through the bony endplate. Results indicate that changes in blood vessels in the vertebral bodies supplying the disc, as well as changes in endplate architecture appear to influence density of cells in intervertebral discs. PMID:23311982

  14. 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

  15. 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.

  16. 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%.

  17. Towards developing algal synthetic biology.

    PubMed

    Scaife, Mark Aden; Smith, Alison Gail

    2016-06-15

    The genetic, physiological and metabolic diversity of microalgae has driven fundamental research into photosynthesis, flagella structure and function, and eukaryotic evolution. Within the last 10 years these organisms have also been investigated as potential biotechnology platforms, for example to produce high value compounds such as long chain polyunsaturated fatty acids, pigments and antioxidants, and for biodiesel precursors, in particular triacylglycerols (TAGs). Transformation protocols, molecular tools and genome sequences are available for a number of model species including the green alga Chlamydomonas reinhardtii and the diatom Phaeodactylum tricornutum, although for both species there are bottlenecks to be overcome to allow rapid and predictable genetic manipulation. One approach to do this would be to apply the principles of synthetic biology to microalgae, namely the cycle of Design-Build-Test, which requires more robust, predictable and high throughput methods. In this mini-review we highlight recent progress in the areas of improving transgene expression, genome editing, identification and design of standard genetic elements (parts), and the use of microfluidics to increase throughput. We suggest that combining these approaches will provide the means to establish algal synthetic biology, and that application of standard parts and workflows will avoid parallel development and capitalize on lessons learned from other systems. PMID:27284033

  18. Thermodynamic performance analysis of a molten carbonate fuel cell at very high current densities

    NASA Astrophysics Data System (ADS)

    Ramandi, M. Y.; Dincer, I.

    2011-10-01

    This study is basically composed of two sections. In the first section, a CFD analysis is used to provide a better insight to molten carbonate fuel cell operation and performance characteristics at very high current densities. Therefore, a mathematical model is developed by employing mass and momentum conservation, electrochemical reaction mechanisms and electric charges. The model results are then compared with the available data for an MCFC unit, and a good agreement is observed. In addition, the model is applied to predict the unit cell behaviour at various operating pressures, temperatures, and cathode gas stoichiometric ratios. In the second section, a thermodynamic model is utilized to examine energy efficiency, exergy efficiency and entropy generation of the MCFC. At low current densities, no considerable difference in output voltage and power is observed; however, for greater values of current densities, the difference is not negligible. If the molten carbonate fuel cell is to operate at current densities smaller than 2500 A m-2, there is no point to pressurize the system. If the fuel cell operates at pressures greater than atmospheric pressure, the unit cell cost could be minimized. In addition, various partial pressure ratios at the cathode side demonstrated nearly the same effect on the performance of the fuel cell. With a 60 K change in operating temperature, almost 10% improvement in energy and exergy efficiencies is obtained. Both efficiencies initially increase at lower current densities and then reach their maximum values and ultimately decrease with the increase of current density. By elevating the pressure, both energy and exergy efficiencies of the cell enhance. In addition, higher operating pressure and temperature decrease the unit cell entropy generation.

  19. 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

  20. 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.

  1. 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. PMID:25899246

  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. Cell response to RGD density in cross-linked artificial extracellular matrix protein films.

    PubMed

    Liu, Julie C; Tirrell, David A

    2008-11-01

    This study examines the adhesion, spreading, and migration of human umbilical vein endothelial cells on cross-linked films of artificial extracellular matrix (aECM) proteins. The aECM proteins described here were designed for application in small-diameter grafts and are composed of elastin-like structural repeats and fibronectin cell-binding domains. aECM-RGD contains the RGD sequence derived from fibronectin; the negative control protein aECM-RDG contains a scrambled cell-binding domain. The covalent attachment of poly(ethylene glycol) (PEG) to aECM substrates reduced nonspecific cell adhesion to aECM-RDG-PEG but did not preclude sequence-specific adhesion of endothelial cells to aECM-RGD-PEG. Variation in ligand density was accomplished by the mixing of aECM-RGD-PEG and aECM-RDG-PEG prior to cross-linking. Increasing the density of RGD domains in cross-linked films resulted in more robust cell adhesion and spreading but did not affect cell migration speed. Control of cell-binding domain density in aECM proteins can thus be used to modulate cell adhesion and spreading and will serve as an important design tool as these materials are further developed for use in surgery, tissue engineering, and regenerative medicine. PMID:18826275

  4. Rapid algal toxicity assay using variable chlorophyll fluorescence for Chlorella kessleri (chlorophyta).

    PubMed

    Kvíderová, Jana

    2010-12-01

    Three methods of algal assays--the standard assay, microassay, and the proposed fluorescence assay--are compared from the point of view of reliability of EC50 detection, the minimum required time for the detection, sensitivity of individual measurement, i.e. at which cell density the particular assay can be used for EC50 estimation, and the time stability of the EC50 values. The assays were performed with green alga Chlorella kessleri strain LARG/1 growing in potassium dichromate solution in Z-medium ranging from 0.01 to 100 mg Cr L⁻¹. The inoculation cell density was set according to the standards to 10⁴ cells mL⁻¹ and according to spectrophotometer/plate reader detection limit. The average EC50 ranged from 0.096 to 0.649 mg Cr L⁻¹ and there were no significant differences in EC50 between the assay type and the inoculation methods with the exception of the significant difference between EC(c)50₇₂ (EC50 established from biomass measured as chlorophyll a concentration after 72 h of cultivation) in the standard assay and EC(r)50 (EC50 derived from growth rate) in the microassay in the standard inoculation experiment due to low variability of their values. The EC(f)50 (EC50 derived from variable fluorescence measurement) values correspond to EC50 values derived from the growth rates. Fluorescence measurement revealed the toxic effect of the chromium after 24 h of exposure at cell density of 5 x 10⁴ cells mL⁻¹, less by half than other used assay methods. The positive correlation of EC(f)50 and time was found in the standard inoculation experiment but opposite effect was observed at the spectrophotometric one. PMID:19551890

  5. Control of Cell Attachment and Spreading on Poly(acrylamide) Brushes with Varied Grafting Density.

    PubMed

    Lilge, Inga; Schönherr, Holger

    2016-01-26

    To achieve spatial control of fibroblast cell attachment and spreading on a biocompatible polymer coating, the effect of poly(acrylamide) (PAAm) brushes with varied grafting density was investigated. The synthesis of the brushes was performed by surface-initiated atom transfer radical polymerization (SI-ATRP). Gold substrates were modified with binary self-assembled monolayers (SAMs) of an initiator and 16-mercaptohexadecanoic acid (MHDA) as an "inert" thiol to initiate the ATRP of AAm. By using different mixtures for the binary SAMs, a series of polymer brushes with varied grafting densities were prepared. The fractional coverage of surface bound initiator was determined by grazing incidence Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and contact angle measurements. A linear relationship between the Br/S ratio determined by XPS and ToF-SIMS versus the fraction of initiator on the surface determined by water contact angle measurements was observed. The varied initiation concentration on the gold substrates yielded PAAm brushes with different thicknesses, indicating a transition from mushroom to brush regimes with increasing grafting density. Thereby we achieved exquisite control of the degree of cell adhesion. Cell attachment experiments with NIH 3T3 fibroblast cells revealed cell spreading on PAAm brushes with low grafting densities (initiator fractional coverage <0.2) as well as a complete passivation by polymer brushes with higher grafting densities. PMID:26771447

  6. A Mediator of Singlet Oxygen Responses in Chlamydomonas reinhardtii and Arabidopsis Identified by a Luciferase-Based Genetic Screen in Algal Cells[W

    PubMed Central

    Shao, Ning; Duan, Guang You; Bock, Ralph

    2013-01-01

    All cells produce reactive oxygen species (ROS) as by-products of their metabolism. In addition to being cytotoxic, ROS act as regulators of a wide range of developmental and physiological processes. Little is known about the molecular mechanisms underlying the perception of ROS and initiation of cellular responses in eukaryotes. Using the unicellular green alga Chlamydomonas reinhardtii, we developed a genetic screen for early components of singlet oxygen signaling. Here, we report the identification of a small zinc finger protein, METHYLENE BLUE SENSITIVITY (MBS), that is required for induction of singlet oxygen–dependent gene expression and, upon oxidative stress, accumulates in distinct granules in the cytosol. Loss-of-function mbs mutants produce singlet oxygen but are unable to fully respond to it at the level of gene expression. Knockout or knockdown of the homologous genes in the higher plant model Arabidopsis thaliana results in mutants that are hypersensitive to photooxidative stress, whereas overexpression produces plants with elevated stress tolerance. Together, our data indicate an important and evolutionarily conserved role of the MBS protein in ROS signaling and provide a strategy for engineering stress-tolerant plants. PMID:24151292

  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. PMID:26211737

  8. Low density lipoprotein uptake by an endothelial-smooth muscle cell bilayer

    SciTech Connect

    Alexander, J.J.; Miguel, R.; Graham, D. )

    1991-03-01

    To study the interaction of endothelial and smooth muscle cells, and the means by which such interaction may affect lipid permeability of the arterial wall, cell bilayers were established by use of a transwell culture system. After confluent growth of both cell types had been achieved, iodine 125 bound to low-density lipoprotein (10 ng protein/ml) was added to the media of the upper well. After a 3-hour incubation period, the iodine 125-bound low-density lipoprotein content of the upper and lower media demonstrated an impedance to lipoprotein movement across the endothelial cell monolayer as compared to the bare porous polycarbonate filter of the transwell (p less than 10(-6)). The presence of smooth muscle cells in the bottom well significantly enhanced the permeability of the endothelial cell layer (p less than 10(-60)). This effect remained unchanged over a 9-day time course. Membrane binding and cellular uptake of low-density lipoprotein by endothelial cells was not altered by smooth muscle cells, indicating that this change in permeability could not be easily attributed to changes in receptor-mediated transport or transcytosis. Membrane binding (p less than 0.02) and cellular uptake (p less than 10(-6)) of low-density lipoprotein by smooth muscle cells in the bilayer, when adjusted for counts available in the smooth muscle cell media, were both reduced in the early incubation period as compared to isolated smooth muscle cells. The disproportionate reduction in uptake as compared to binding would suggest that this was not entirely a receptor-dependent process.

  9. Tissue non-specific alkaline phosphatase production by human dental pulp stromal cells is enhanced by high density cell culture.

    PubMed

    Tomlinson, Matthew J; Dennis, Caitriona; Yang, Xuebin B; Kirkham, Jennifer

    2015-08-01

    The cell surface hydrolase tissue non-specific alkaline phosphatase (TNAP) (also known as MSCA-1) is used to identify a sub-population of bone marrow stromal cells (BMSCs) with high mineralising potential and is found on subsets of cells within the dental pulp. We aim to determine whether TNAP is co-expressed by human dental pulp stromal cells (hDPSCs) alongside a range of BMSC markers, whether this is an active form of the enzyme and the effects of culture duration and cell density on its expression. Cells from primary dental pulp and culture expanded hDPSCs expressed TNAP. Subsequent analyses revealed persistent TNAP expression and co-expression with BMSC markers such as CD73 and CD90. Flow cytometry and biochemical assays showed that increased culture durations and cell densities enhanced TNAP expression by hDPSCs. Arresting the hDPSC cell cycle also increased TNAP expression. These data confirm that TNAP is co-expressed by hDPSCs together with other BMSC markers and show that cell density affects TNAP expression levels. We conclude that TNAP is a potentially useful marker for hDPSC selection especially for uses in mineralised tissue regenerative therapies. PMID:25636587

  10. 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.

  11. 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. PMID:22481299

  12. Elevated Periimplantation Uterine Natural Killer Cell Density in Human Endometrium Is Associated With Impaired Corticosteroid Signaling in Decidualizing Stromal Cells

    PubMed Central

    Kuroda, Keiji; Venkatakrishnan, Radha; James, Sean; Šućurović, Sandra; Mulac-Jericevic, Biserka; Lucas, Emma S.; Takeda, Satoru; Shmygol, Anatoly; Brosens, Jan J.

    2013-01-01

    Background: Decidualizing human endometrial stromal cells (HESCs) profoundly up-regulate 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), the enzyme that converts inert cortisone to active cortisol. We postulated that the induction of a cortisol gradient upon decidualization of the periimplantation endometrium may impact on the uterine natural killer (uNK) cell population and on local expression of corticosteroid-dependent target genes. Methods: Midluteal endometrial biopsies (n = 55) were processed for uNK cell (CD56) analysis and primary HESC cultures. The cultures remained either untreated or were decidualized for 4 or 8 days. A tissue microarray was constructed from endometria with normal (n = 18) and elevated uNK cell (n = 18) scores. An abnormal uNK cell test was defined as greater than 5% CD56+ cells in the subluminal stroma. Results: Increased uNK cell density was associated with lower endometrial expression of 11βHSD1 and mineralocorticoid receptor (MR) but not glucocorticoid receptor in vivo. Elevated uNK cell density also corresponded to impaired induction of key decidual markers (11βHSD1, prolactin, and insulin-like growth factor binding protein-1) and MR-dependent enzymes (dehydrogenase/reductase member 3 and retinol saturase) in differentiating HESC cultures. Increased uNK cell density in vivo was not associated with increased in vitro expression of either IL-15 or IL-11, two cytokines implicated in uNK cell regulation. Conclusions: Elevated levels of uNK cells in the stroma underlying the surface epithelium are associated with inadequate cortisol biosynthesis by resident decidualizing cells and suboptimal induction of key MR-dependent enzymes involved in lipid biogenesis and the retinoid transport pathway. Our observations suggest that uNK cell testing identifies those women at risk of reproductive failure due to relative uterine cortisol deficiency. PMID:24025400

  13. 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

  14. Autonomous bacterial localization and gene expression based on nearby cell receptor density

    PubMed Central

    Wu, Hsuan-Chen; Tsao, Chen-Yu; Quan, David N; Cheng, Yi; Servinsky, Matthew D; Carter, Karen K; Jee, Kathleen J; Terrell, Jessica L; Zargar, Amin; Rubloff, Gary W; Payne, Gregory F; Valdes, James J; Bentley, William E

    2013-01-01

    Escherichia coli were genetically modified to enable programmed motility, sensing, and actuation based on the density of features on nearby surfaces. Then, based on calculated feature density, these cells expressed marker proteins to indicate phenotypic response. Specifically, site-specific synthesis of bacterial quorum sensing autoinducer-2 (AI-2) is used to initiate and recruit motile cells. In our model system, we rewired E. coli's AI-2 signaling pathway to direct bacteria to a squamous cancer cell line of head and neck (SCCHN), where they initiate synthesis of a reporter (drug surrogate) based on a threshold density of epidermal growth factor receptor (EGFR). This represents a new type of controller for targeted drug delivery as actuation (synthesis and delivery) depends on a receptor density marking the diseased cell. The ability to survey local surfaces and initiate gene expression based on feature density represents a new area-based switch in synthetic biology that will find use beyond the proposed cancer model here. PMID:23340842

  15. 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. PMID:24400863

  16. 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.

  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. 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.

  20. Detection and density estimation of goblet cells in confocal endoscopy for the evaluation of celiac disease.

    PubMed

    Boschetto, D; Mirzaei, H; Leong, R W L; Grisan, E

    2015-08-01

    Celiac Disease (CD) is an immune-mediated enteropathy, diagnosed in the clinical practice by intestinal biopsy and the concomitant presence of a positive celiac serology. Confocal Laser Endomicroscopy (CLE) allows skilled and trained experts to potentially perform in vivo virtual histology of small-bowel mucosa. In particular, it allows the qualitative evaluation of mucosa alteration such as a decrease in goblet cells density, presence of villous atrophy or crypt hypertrophy. We present a semi-automatic computer-based method for the detection of goblet cells from confocal endoscopy images, whose density changes in case of pathological tissue. After a manual selection of a suitable region of interest, the candidate columnar and goblet cells' centers are first detected and the cellular architecture is estimated from their position using a Voronoi diagram. The region within each Voronoi cell is then analyzed and classified as goblet cell or other. The results suggest that our method is able to detect and label goblet cells immersed in a columnar epithelium in a fast, reliable and automatic way. Accepting 0.44 false positives per image, we obtain a sensitivity value of 90.3%. Furthermore, estimated and real goblet cell densities are comparable (error: 9.7 ± 16.9%, correlation: 87.2%, R(2) = 76%). PMID:26737720

  1. Inhibition of transferrin receptor 1 transcription by a cell density response element

    PubMed Central

    2005-01-01

    TfR1 (transferrin receptor 1) mediates the uptake of transferrin-bound iron and thereby plays a critical role in cellular iron metabolism. Its expression is coupled to cell proliferation/differentiation and controlled in response to iron levels and other signals by transcriptional and post-transcriptional mechanisms. It is well established that TfR1 levels decline when cultured cells reach a high density and in the present study we have investigated the underlying mechanisms. Consistent with previous findings, we demonstrate that TfR1 expression is attenuated in a cell-density-dependent manner in human lung cancer H1299 cells and in murine B6 fibroblasts as the result of a marked decrease in mRNA content. This response is not associated with alterations in the RNA-binding activity of iron regulatory proteins that are indicative of a transcriptional mechanism. Reporter assays reveal that the human TfR1 promoters contains sequences mediating cell-density-dependent transcriptional inhibition. Mapping of the human and mouse TfR1 promoters identified a conserved hexa-nucleotide 5′-GAGGGC-3′ motif with notable sequence similarity to a previously described element within the IGF-2 (insulin-like growth factor-2) promoter. We show that this motif is necessary for the formation of specific complexes with nuclear extracts and for cell-density-dependent regulation in reporter gene assays. Thus the TfR1 promoter contains a functional ‘cell density response element’ (CDRE). PMID:16092918

  2. Heparin effect on DNA synthesis in a murine fibrosarcoma cell line: influence of anionic density

    SciTech Connect

    Piepkorn, M.W.; Daynes, R.A.

    1983-09-01

    The effects of heparin subfractions on DNA synthesis in a murine cutaneous fibrosarcoma cell line were examined. Porcine mucosal heparin was preparatively fractionated for anionic charge density by DEAE-Sephadex chromatography and for molecular weight by Sephadex G-100 filtration. The cell line was plated from confluent monolayer cultures and grown in medium and fetal bovine serum, with or without a heparin fraction at a final concentration of 10 micrograms/ml. At intervals thereafter, the cells were pulsed with (/sup 3/H)thymidine. A low-charge density heparin fraction stimulated (/sup 3/H)thymidine incorporation (cpm/mg protein and cpm/cell) during the first 3 days of growth compared to control values without added heparin, whereas a high-charge density heparin fraction had little of this effect (186 +/- 35% of control vs. 101 +/- 14%, respectively; P less than .05). The augmentation of DNA synthesis observed with the low-charge density fraction correlated with increased proportions of cells in S and G2 phases compared with those of the controls, as determined by flow cytofluorometry. Low- and high-molecular-weight heparin fractions did not significantly alter DNA synthesis. Heparin subfractions are thus heterogeneous with respect to their effect on cellular DNA synthesis in this tumor line.

  3. 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.

  4. Multi-Cell High Latitude Density Structure Induced by Ion Drag during Active Periods

    NASA Astrophysics Data System (ADS)

    Walterscheid, R. L.; Crowley, G.

    2012-12-01

    During active periods two-cell convection patterns can produce four-cell density structure in the high-latitude thermosphere. During these periods density perturbations approaching 50% are possible. The occurrence of density structures that are more complex than the forcing itself suggests that the structure is caused by a profound change in the balance of forces. Using a General Circulation Model of the thermosphere, we compare the balance of forces in the upper and lower thermosphere during active and quiet times. We also examine the thermal structure caused by the dynamical adjustment to ion-drag forcing in relation to the other terms as a balanced state is approached. Simulations reveal that where ion drag is unable to accelerate the atmosphere into rapid motion (during quiet times or at low thermospheric altitudes) the Coriolis force is the dominant inertial term, and for fixed pressure levels centers of cyclonic motion are (per the usual meteorology relations) colder and denser than the surrounding air, while centers of anticyclonic motion are warmer and less dense. At fixed heights, densities are high in the evening anticyclonic gyre, and low in the dawn cyclonic gyre. However, this situation is radically changed during active periods when the atmosphere is spun up to rapid motion and the centrifugal force resulting from curved trajectories is the dominant inertial force. When this occurs, the high latitude anticyclones and cyclones both become centers of relatively cold high density air at fixed height. Cold low-density centers are found on both the dawn and dusk sides with a trough of low density air over the pole connecting them. This intrusion of low density splits the evening high density region that exists under quiet conditions giving the four cell pattern found by Crowley et al. [1989; 1996a, b]. Crowley, G., J. Schoendorf, R. G. Roble, F. A. Marcos (1996a). Cellular structures in the high latitude lower thermosphere, J. Geophys. Res. 101, 211

  5. Algal photoreceptors: in vivo functions and potential applications.

    PubMed

    Kianianmomeni, Arash; Hallmann, Armin

    2014-01-01

    Many algae, particularly microalgae, possess a sophisticated light-sensing system including photoreceptors and light-modulated signaling pathways to sense environmental information and secure the survival in a rapidly changing environment. Over the last couple of years, the multifaceted world of algal photobiology has enriched our understanding of the light absorption mechanisms and in vivo function of photoreceptors. Moreover, specific light-sensitive modules have already paved the way for the development of optogenetic tools to generate light switches for precise and spatial control of signaling pathways in individual cells and even in complex biological systems. PMID:24081482

  6. Cell density-dependent nuclear accumulation of ELK3 is involved in suppression of PAI-1 expression.

    PubMed

    Tanaka, Shu; Nakao, Kazuyuki; Sekimoto, Toshihiro; Oka, Masahiro; Yoneda, Yoshihiro

    2013-07-01

    Cell-cell contact regulates the proliferation and differentiation of non-transformed cells, e.g., NIH/3T3 cells show growth arrest at high cell density. However, only a few reports described the dynamic behavior of transcription factors involved in this process. In this study, we showed that the mRNA levels of plasminogen activator inhibitor type 1 (PAI-1) decreased drastically at high cell density, and that ELK3, a member of the Ets transcription factor family, repressed PAI-1 expression. We also demonstrated that while ELK3 was distributed evenly throughout the cell at low cell density, it accumulated in the nucleus at high cell density, and that binding of DNA by ELK3 at the A domain facilitated its nuclear accumulation. Furthermore, we found that ETS1, a PAI-1 activator, occupied the ELK3-binding site within the PAI-1 promoter at low cell density, while it was released at high cell density. These results suggest that at high cell density, the switching of binding of transcription factors from ETS1 to ELK3 occurs at a specific binding site of the PAI-1 promoter, leading to the cell-density dependent suppression of PAI-1 expression. PMID:23708702

  7. 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.

  8. Effect of the peak cell density of recombinant AcMNPV-infected Hi5 cells on baculovirus yields.

    PubMed

    Huynh, Hoai T; Tran, Trinh T B; Chan, Leslie C L; Nielsen, Lars K; Reid, Steven

    2015-02-01

    The phenomenon of the cell density effect is not readily explained by an obvious nutrient limitation, and a recent study has suggested that for recombinant Autographa californica multiple nucleopolyhedrovirus (rAcMNPV)-infected Sf9 cells, a drop in messenger RNA (mRNA) levels may be sufficient to explain the cell density effect for this system. The current study aims to investigate the response in cell-specific yields (viral DNA (vDNA), LacZ mRNA and β-galactosidase (β-Gal) protein) with increasing infection cell density (ICD) for rAcMNPV-infected Hi5 cells, where the rAcMNPV expresses the β-Gal gene under control of the polyhedral promoter. Hi5 cells in suspension culture of Express Five® medium were synchronously infected with a rAcMNPV at multiple ICDs between 0.5 and 6 × 10(6) cells/mL and a multiplicity of infection of 10 plaque-forming units (PFU)/cell either in the original or fresh medium conditions. There were negative correlations between the three key virus infection indicators (vDNA, mRNA and β-Gal) and the peak cell density (PCD). However, unlike infected Sf9 cells, the yield decline started at the lowest PCD investigated (0.6 × 10(6) cells/mL). Generally, the yield decline with increasing PCD was most pronounced for β-Gal followed by mRNA and was more moderate for vDNA. The decline was significantly reduced but not totally arrested when fresh medium replacement was used. The results suggest that the reduction in recombinant protein-specific yields at high PCDs is associated with limitations during the up-stream processes of replication and transcription rather than entirely caused by limitations during translation. In addition, low production rates at late infection stages of moderate to high ICDs are a probable cause of the cell density effect. PMID:25472440

  9. The Role of Surface Receptor Density in Surface-Initiated Polymerizations for Cancer Cell Isolation.

    PubMed

    Lilly, Jacob L; Berron, Brad J

    2016-06-01

    Fluid biopsies potentially offer a minimally invasive alternative to traditional tissue biopsies for the continual monitoring of metastatic cancer. Current established technologies for isolating circulating tumor cells (CTCs) suffer from poor purity and yield and require fixatives that preclude the collection of viable cells for longitudinal analyses of biological function. Antigen specific lysis (ASL) is a rapid, high-purity method of cell isolation based on targeted protective coatings on antigen-presenting cells and lysis depletion of unprotected antigen-negative cells. In ASL, photoinitiators are specifically labeled on cell surfaces that enable subsequent surface-initiated polymerization. Critically, the significant determinants of process yield have yet to be investigated for this emerging technology. In this work, we show that the labeling density of photoinitiators is strongly correlated with the yield of intact cells during ASL by flow cytometry analysis. Results suggest ASL is capable of delivering ∼25% of targeted cells after isolation using traditional antibody labeling approaches. Monomer formulations of two molecular weights of PEG-diacrylate (Mn ∼ 575 and 3500) are examined. The gelation response during ASL polymerization is also investigated via protein microarray analogues on planar glass. Finally, a density threshold of photoinitiator labeling required for protection during lysis is determined for both monomer formulations. These results indicate ASL is a promising technology for high yield CTC isolation for rare-cell function assays and fluid biopsies. PMID:27206735

  10. 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

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

    DOE PAGESBeta

    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 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

  12. 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.

  13. Effect of spaceflight on Pseudomonas aeruginosa final cell density is modulated by nutrient and oxygen availability

    PubMed Central

    2013-01-01

    Background Abundant populations of bacteria have been observed on Mir and the International Space Station. While some experiments have shown that bacteria cultured during spaceflight exhibit a range of potentially troublesome characteristics, including increases in growth, antibiotic resistance and virulence, other studies have shown minimal differences when cells were cultured during spaceflight or on Earth. Although the final cell density of bacteria grown during spaceflight has been reported for several species, we are not yet able to predict how different microorganisms will respond to the microgravity environment. In order to build our understanding of how spaceflight affects bacterial final cell densities, additional studies are needed to determine whether the observed differences are due to varied methods, experimental conditions, or organism specific responses. Results Here, we have explored how phosphate concentration, carbon source, oxygen availability, and motility affect the growth of Pseudomonas aeruginosa in modified artificial urine media during spaceflight. We observed that P. aeruginosa grown during spaceflight exhibited increased final cell density relative to normal gravity controls when low concentrations of phosphate in the media were combined with decreased oxygen availability. In contrast, when the availability of either phosphate or oxygen was increased, no difference in final cell density was observed between spaceflight and normal gravity. Because motility has been suggested to affect how microbes respond to microgravity, we compared the growth of wild-type P. aeruginosa to a ΔmotABCD mutant deficient in swimming motility. However, the final cell densities observed with the motility mutant were consistent with those observed with wild type for all conditions tested. Conclusions These results indicate that differences in bacterial final cell densities observed between spaceflight and normal gravity are due to an interplay between

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

    PubMed Central

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

    2013-01-01

    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. PMID:23778164

  15. Density increment and decreased survival of rat red blood cells induced by cadmium

    SciTech Connect

    Kunimoto, M.; Miura, T.

    1986-01-01

    Male Wistar rats were injected with CdCl/sub 2/ subcutaneously to examine in vivo effects of Cd on density and survival of red blood cells. During the 7 days after administration of 1.0 mg Cd/kg, the following sequence of events occurred: (1) a progressive increase in the amount of more dense red blood cells concomitant with a decrease in that of light red blood cells from the first to the third day; (2) an increase in the spleen weight at the third day; (3) a decrease in the hematocrit value and an increase in the amount of light red blood cells at the fifth day; and (4) a recovery of the hematocrit value at the seventh day. Five days after administration, the hematocrit value decreased in a dose-dependent mode and the decrease was significant at the 1% level at 1.0 and 1.5 mg Cd/kg. A highly significant splenomegaly was also observed at 0.5 to 1.5 mg Cd/kg. In order to label red blood cells in vivo, (/sup 3/H) diisopropylfluorophosphate ((/sup 3/H)DFP) was injected into rats. At Day 11, Cd at either 0.5 or 1.0 mg/kg was administered to (/sup 3/H)DFP-prelabeled animals. Cd administration accelerated /sup 3/H-labeled red cell clearance from the blood. Six days after Cd administration, the radioactivity of red blood cells was 76 and 68% of the control at 0.5 and 1.0 mg Cd/kg, respectively. In vitro treatment of rat red density and accelerated in vivo clearance of red blood cells from the recipient circulation. These results show that Cd at low dose can cause anemia by increasing red cell density and by accelerating red cell sequestration, presumably in the spleen.

  16. Common European harmful algal blooms affect the viability and innate immune responses of Mytilus edulis larvae.

    PubMed

    De Rijcke, M; Vandegehuchte, M B; Vanden Bussche, J; Nevejan, N; Vanhaecke, L; De Schamphelaere, K A C; Janssen, C R

    2015-11-01

    Like marine diseases, harmful algal blooms (HABs) are globally increasing in frequency, severity and geographical scale. As a result, bivalves will have to face the combined threat of toxic algae and marine pathogens more frequently in the (near) future. These stressors combined may further affect the recruitment of ecologically and economically important bivalve species as HABs can affect the growth, viability and development of their larvae. To date, little is known on the specific effects of HABs on the innate immune system of bivalve larvae. This study therefore investigates whether two common harmful algae can influence the larval viability, development and immunological resilience of the blue mussel Mytilus edulis. Embryos of this model organism were exposed (48 h) to five densities of Pseudo-nitzschia multiseries or Prorocentrum lima cells. In addition, the effect of six concentrations of their respective toxins: domoic acid (DA) and okadaic acid (OA) were assessed. OA was found to significantly reduce larval protein phosphatase activity (p < 0.001) and larval viability (p < 0.01) at concentrations as low as 37.8 μg l(-1). P. multiseries (1400 cells ml(-1)), P. lima (150 cells ml(-1)) and DA (dosed five times higher than typical environmental conditions i.e. 623.2 μg l(-1)) increased the phenoloxidase (PO) innate immune activity of the mussel larvae. These results suggest that the innate immune response of even the earliest life stages of bivalves is susceptible to the presence of HABs. PMID:26348409

  17. Detection of toxic organometallic complexes in wastewaters using algal assays.

    PubMed

    Wong, S L; Nakamoto, L; Wainwright, J F

    1997-05-01

    Chlorella (a unicellular green alga) and Cladophora (a filamentous alga) were used in algal assays to identify the presence and toxicity of organometallic complexes in four industrial wastewaters. Toxicities of inorganic Pb and organometallic compounds (trimethyl, tetramethyl and tetraethyl leads, cacodylic acid and Cu-picolinate) were examined, using algal cells grown in 10% BBM solution. Inorganic Pb and organometallic compounds altered the fine structure of Chlorella cells in a distinguishable manner. X-ray microanalysis revealed that organometallic compounds accumulated in the neutral lipids of Cladophora cells. By applying the above techniques to the wastewater assays, two of the four wastewaters tested were found to contain organometallic complexes. Wastewater from a chemical company contained only traces of organo-Cu, but one mining effluent contained significant quantities of organo-Cu and organo-Pb, and traces of organo-Cr and organo-Tl (thallium). These studies suggest that X-ray microanalysis of algae may be a useful tool in identifying aquatic systems contaminated with metals and organometallic compounds. PMID:9175500

  18. 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

  19. 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.

  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. PMID:25481308

  1. 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

  2. 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...

  3. CELL DENSITY AND NON-EQUILIBRIUM SORPTION EFFECTS ON BACTERIAL DISPERSAL IN GROUNDWATER MICROCOSMS

    EPA Science Inventory

    The relative importance of dispersion, physical straining, non-equilibrium sorption, and cell density on the dispersal of bacteria was examined in saturated, flow-dynamic sand columns. The bacterial breakthrough as a was followed by measuring the effluent concentration of 3H-aden...

  4. 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

  5. A new mitochondrial pool of cyclin E, regulated by Drp1, is linked to cell-density-dependent cell proliferation.

    PubMed

    Parker, Danitra J; Iyer, Archana; Shah, Shikha; Moran, Aida; Hjelmeland, Anita B; Basu, Malay Kumar; Liu, Runhua; Mitra, Kasturi

    2015-11-15

    The regulation and function of the crucial cell cycle regulator cyclin E (CycE) remains elusive. Unlike other cyclins, CycE can be uniquely controlled by mitochondrial energetics, the exact mechanism being unclear. Using mammalian cells (in vitro) and Drosophila (in vivo) model systems in parallel, we show that CycE can be directly regulated by mitochondria through its recruitment to the organelle. Active mitochondrial bioenergetics maintains a distinct mitochondrial pool of CycE (mtCycE) lacking a key phosphorylation required for its degradation. Loss of the mitochondrial fission protein dynamin-related protein 1 (Drp1, SwissProt O00429 in humans) augments mitochondrial respiration and elevates the mtCycE pool allowing CycE deregulation, cell cycle alterations and enrichment of stem cell markers. Such CycE deregulation after Drp1 loss attenuates cell proliferation in low-cell-density environments. However, in high-cell-density environments, elevated MEK-ERK signaling in the absence of Drp1 releases mtCycE to support escape of contact inhibition and maintain aberrant cell proliferation. Such Drp1-driven regulation of CycE recruitment to mitochondria might be a mechanism to modulate CycE degradation during normal developmental processes as well as in tumorigenic events. PMID:26446260

  6. Cell Density Sensing Alters TGF-β Signaling in a Cell-Type-Specific Manner, Independent from Hippo Pathway Activation

    PubMed Central

    Nallet-Staub, Flore; Yin, Xueqian; Gilbert, Cristèle; Marsaud, Véronique; Ben Mimoun, Saber; Javelaud, Delphine; Leof, Edward B.; Mauviel, Alain

    2015-01-01

    SUMMARY Cell-cell contacts inhibit cell growth and proliferation in part by activating the Hippo pathway that drives the phosphorylation and nuclear exclusion of the transcriptional coactivators YAP and TAZ. Cell density and Hippo signaling have also been reported to block transforming growth factor β (TGF-β) responses, based on the ability of phospho-YAP/TAZ to sequester TGF-β-activated SMAD complexes in the cytoplasm. Herein, we provide evidence that epithelial cell polarization interferes with TGF-β signaling well upstream and independent of cytoplasmic YAP/TAZ. Rather, polarized basolateral presentation of TGF-β receptors I and II deprives apically delivered TGF-β of access to its receptors. Basolateral ligand delivery nonetheless remains entirely effective to induce TGF-β responses. These data demonstrate that cell-type-specific inhibition of TGF-β signaling by cell density is restricted to polarized epithelial cells and reflects the polarized distribution of TGF-β receptors, which thus affects SMAD activation irrespective of Hippo pathway activation. PMID:25758862

  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. PMID:23827782

  8. Influence of cell wall shape and density on the mechanical behaviour of 2D foam structures

    SciTech Connect

    Harders, Harald . E-mail: h.harders@tu-bs.de; Hupfer, Knut; Roesler, Joachim

    2005-03-01

    This article describes simulations on the influence of the cell wall shape as well as the density on the elastic stiffness of regular and stochastic honeycomb structures. Starting from an equation by Gibson and Ashby for regular honeycombs, an analytical model is developed that describes the influence of different cell wall shapes on the elastic response of these structures. In addition, this analytical model is modified in order to use free parameters that can be fitted to finite element simulation results of stochastic Voronoi honeycomb structures. The model describes the results well. Young's modulus depends strongly on the cell wall shape, achieving a maximum for slightly concave shapes.

  9. 40 CFR 797.1050 - Algal acute toxicity test.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) Algistatic means having the property of inhibiting algal growth. (3) ECx means the experimentally derived chemical concentration that is calculated to effect X percent of the test criterion. (4) Growth means a relative measure of the viability of an algal population based on the number and/or weight of algal...

  10. 40 CFR 797.1050 - Algal acute toxicity test.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) Algistatic means having the property of inhibiting algal growth. (3) ECx means the experimentally derived chemical concentration that is calculated to effect X percent of the test criterion. (4) Growth means a relative measure of the viability of an algal population based on the number and/or weight of algal...

  11. 40 CFR 797.1050 - Algal acute toxicity test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) Algistatic means having the property of inhibiting algal growth. (3) ECx means the experimentally derived chemical concentration that is calculated to effect X percent of the test criterion. (4) Growth means a relative measure of the viability of an algal population based on the number and/or weight of algal...

  12. Approaches for the detection of harmful algal blooms using oligonucleotide interactions.

    PubMed

    Bruce, Karen L; Leterme, Sophie C; Ellis, Amanda V; Lenehan, Claire E

    2015-01-01

    Blooms of microscopic algae in our waterways are becoming an increasingly important environmental concern. Many are sources of harmful biotoxins that can lead to death in humans, marine life and birds. Additionally, their biomass can cause damage to ecosystems such as oxygen depletion, displacement of species and habitat alteration. Globally, the number and frequency of harmful algal blooms has increased over the last few decades, and monitoring and detection strategies have become essential for managing these events. This review discusses developments in the use of oligonucleotide-based 'molecular probes' for the selective monitoring of algal cell numbers. Specifically, hybridisation techniques will be a focus. PMID:25381608

  13. 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

  14. Use of a mixed algal culture to characterize industrial waste waters

    SciTech Connect

    Claesson, A.

    1984-02-01

    A mixture of five freshwater algae was cultivated with additions of waste water samples from chemical, mining, polyvinylchloride, textile, paper mill, and oil refinery industries. Two water samples from chemical industries and one from an oil refinery stimulated the algal growth in a nutrient-poor medium, while growth in other samples, including a nutrient-rich medium, was inhibited in several different ways. For eight of the water samples a delayed growth of 2-4 days was noted. Decreased growth rate and lowered maximal biomass occurred in seven of the samples. The photosynthetic capacity of the algal cells was measured by using in vivo fluorescence of chlorophyll a. These quick measurements mostly agreed with those of the growth rates. When the species composition of the mixed algal culture was investigated, large differences in sensitivities between the different species were found. Stimulation or inhibition were observed in the same sample for different species but also for the same species at different concentrations.

  15. 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

  16. Metabolism of mutagenic polycyclic aromatic hydrocarbons by photosynthetic algal species.

    PubMed

    Schoeny, R; Cody, T; Warshawsky, D; Radike, M

    1988-02-01

    Polycyclic aromatic hydrocarbons (PAH) known to produce carcinogenic and mutagenic effects have been shown to contaminate waters, sediments and soils. While it is accepted that metabolites of these compounds are responsible for most of their biological effects in mammals, their metabolism, and to a large extent their bioactivity, in aquatic plants have not been explored. Cultures of photosynthetic algal species were assayed for their ability to metabolize benzo[a]pyrene (BaP), a carcinogenic PAH under conditions which either permitted (white light) or disallowed (gold light) photooxidation of the compound. Growth of Selenastrum capricornutum, a fresh-water green alga, was completely inhibited when incubated in white light with 160 micrograms BaP/l medium. By contrast concentrations at the upper limit of BaP solubility in aqueous medium had no effect on algal growth when gold light was used. BaP quinones and phenol derivatives were found to inhibit growth of Selenastrum under white light incubation. BaP phototoxicity and metabolism were observed to be species-specific. All 3 tested species of the order Chlorococcales were growth-inhibited by BaP in white light whereas neither the green alga Chlamydomonas reinhardtii nor a blue-green, a yellow-green or an euglenoid alga responded in this fashion. Assays of radiolabeled BaP metabolism in Selenastrum showed that the majority of radioactivity associated with BaP was found in media as opposed to algal cell pellets, that the extent of metabolism was BaP concentration dependent, and that the proportion of various metabolites detected was a function of the light source. After gold light incubation, BaP diols predominated while after white light treatment at equal BaP concentrations, the 3,6-quinone was found in the highest concentration. Extracted material from algal cell pellets and from media was tested for mutagenicity in a forward mutation suspension assay in Salmonella typhimurium using resistance to 8-azaguanine for

  17. 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.

  18. 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.

  19. Anatomical Mapping and Density of Merkel Cells in Skin and Mucosae of the Dog.

    PubMed

    Ramírez, Gustavo A; Rodríguez, Francisco; Quesada, Óscar; Herráez, Pedro; Fernández, Antonio; Espinosa-de-Los-Monteros, Antonio

    2016-09-01

    Merkel cells (MCs) are specialized cutaneous receptor cells involved with tactile sense. Although the distribution of MCs has been extensively studied in humans and rodents, their precise distribution and density throughout skin in the dog has not previously been determined. Knowledge of their distribution could facilitate understanding of their functions. By using of immunohistochemistry, density, and anatomical mapping of the MCs population in the dog skin was determined. Assessment of the MCs innervation was also achieved. Different patterns were noted in epidermis, hair follicles, or mucosa, including variable-sized clusters, linear or horse-shaped arrangements, and scattered and individualized cells. MCs revealed great variations in density and distribution over the body surface, with the highest numbers in oral mucosa and facial skin. There was no correlation of MCs density with age, sex, type of breed, coat type or pigmentation. Between 41 and 65% of MCs in hairy and glabrous skin and 8-18% of MCs in oral mucosa were in intimate contact with intraepithelial axon terminals. These findings indicate that canine MCs are numerous in sensory receptive areas and may be associated with the tactile sense in the dog. The present article enhances the knowledge of the skin structure in this species. Anat Rec, 299:1157-1164, 2016. © 2016 Wiley Periodicals, Inc. PMID:27341526

  20. 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)

  1. Bacilysin from Bacillus amyloliquefaciens FZB42 Has Specific Bactericidal Activity against Harmful Algal Bloom Species

    PubMed Central

    Wu, Liming; Wu, Huijun; Chen, Lina; Xie, Shanshan; Zang, Haoyu; Borriss, Rainer

    2014-01-01

    Harmful algal blooms, caused by massive and exceptional overgrowth of microalgae and cyanobacteria, are a serious environmental problem worldwide. In the present study, we looked for Bacillus strains with sufficiently strong anticyanobacterial activity to be used as biocontrol agents. Among 24 strains, Bacillus amyloliquefaciens FZB42 showed the strongest bactericidal activity against Microcystis aeruginosa, with a kill rate of 98.78%. The synthesis of the anticyanobacterial substance did not depend on Sfp, an enzyme that catalyzes a necessary processing step in the nonribosomal synthesis of lipopeptides and polyketides, but was associated with the aro gene cluster that is involved in the synthesis of the sfp-independent antibiotic bacilysin. Disruption of bacB, the gene in the cluster responsible for synthesizing bacilysin, or supplementation with the antagonist N-acetylglucosamine abolished the inhibitory effect, but this was restored when bacilysin synthesis was complemented. Bacilysin caused apparent changes in the algal cell wall and cell organelle membranes, and this resulted in cell lysis. Meanwhile, there was downregulated expression of glmS, psbA1, mcyB, and ftsZ—genes involved in peptidoglycan synthesis, photosynthesis, microcystin synthesis, and cell division, respectively. In addition, bacilysin suppressed the growth of other harmful algal species. In summary, bacilysin produced by B. amyloliquefaciens FZB42 has anticyanobacterial activity and thus could be developed as a biocontrol agent to mitigate the effects of harmful algal blooms. PMID:25261512

  2. 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

  3. 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. PMID:25858243

  4. 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.

  5. Resolving Mixed Algal Species in Hyperspectral Images

    PubMed Central

    Mehrubeoglu, Mehrube; Teng, Ming Y.; Zimba, Paul V.

    2014-01-01

    We investigated a lab-based hyperspectral imaging system's response from pure (single) and mixed (two) algal cultures containing known algae types and volumetric combinations to characterize the system's performance. The spectral response to volumetric changes in single and combinations of algal mixtures with known ratios were tested. Constrained linear spectral unmixing was applied to extract the algal content of the mixtures based on abundances that produced the lowest root mean square error. Percent prediction error was computed as the difference between actual percent volumetric content and abundances at minimum RMS error. Best prediction errors were computed as 0.4%, 0.4% and 6.3% for the mixed spectra from three independent experiments. The worst prediction errors were found as 5.6%, 5.4% and 13.4% for the same order of experiments. Additionally, Beer-Lambert's law was utilized to relate transmittance to different volumes of pure algal suspensions demonstrating linear logarithmic trends for optical property measurements. PMID:24451451

  6. AL HARMFUL ALGAL BLOOM (HAB) INFORMATION EXCHANGE

    EPA Science Inventory

    This project proposes to implement an integrated web site that will serve as an Alabama Harmful Algal Bloom (HAB) Information Exchange Network. This network will be a stand-alone site where HAB data from all agencies and research efforts in the State of Alabama will be integrate...

  7. Using hyperspectral imagery to monitor algal persence

    SciTech Connect

    Anderson, J.M.; Monk, J.; Yan, Gu; Brignal, W.

    1997-08-01

    This paper illustrates how an inexpensive and easily deployable imaging spectrometer can be used to monitor and identify algal blooms at short notice, thus making practical the addition of airborne data to the usual in-situ measurements. Two examples are described, one in the Irish Sea and the other in a reservoir system in the London area.

  8. 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. PMID:21977667

  9. Slugs' last meals: molecular identification of sequestered chloroplasts from different algal origins in Sacoglossa (Opisthobranchia, Gastropoda).

    PubMed

    Händeler, Katharina; Wägele, Heike; Wahrmund, Ute; Rüdinger, Mareike; Knoop, Volker

    2010-11-01

    Some sacoglossan sea slugs have become famous for their unique capability to extract and incorporate functional chloroplasts from algal food organisms (mainly Ulvophyceae) into their gut cells. The functional incorporation of the so-called kleptoplasts allows the slugs to rely on photosynthetic products for weeks to months, enabling them to survive long periods of food shortage over most of their life-span. The algal food spectrum providing kleptoplasts as temporary, non-inherited endosymbionts appears to vary among sacoglossan slugs, but detailed knowledge is sketchy or unavailable. Accurate identification of algal donor species, which provide the chloroplasts for long-term retention is of primary importance to elucidate the biochemical mechanisms allowing long-term functionality of the captured chloroplast in the foreign animal cell environment. Whereas some sacoglossans forage on a variety of algal species, (e.g. Elysia crispata and E. viridis) others are more selective. Hence, characterizing the range of functional sacoglossan-chloroplast associations in nature is a prerequisite to understand the basis of this enigmatic endosymbiosis. Here, we present a suitable chloroplast gene (tufA) as a marker, which allows identification of the respective algal kleptoplast donor taxa by analysing DNA from whole animals. This novel approach allows identification of donor algae on genus or even species level, thus providing evidence for the taxonomic range of food organisms. We report molecular evidence that chloroplasts from different algal sources are simultaneously incorporated in some species of Elysia. NeigborNet analyses for species assignments are preferred over tree reconstruction methods because the former allow more reliable statements on species identification via barcoding, or rather visualize alternative allocations not to be seen in the latter. PMID:21565106

  10. Topical Substance P Increases Inflammatory Cell Density in Genetically Diabetic Murine Wounds

    PubMed Central

    Scott, Jeffrey R; Tamura, Richard N.; Muangman, Pornprom; Isik, F. Frank; Xie, Chengyu; Gibran, Nicole S.

    2008-01-01

    The neuropeptide substance P (SP) is a known inflammatory mediator released from cutaneous peripheral nerve terminals. SP effects on cellular composition in the cutaneous response to injury remain unclear. Based on our previous observations about SP effects on wound repair, we hypothesized that topical SP increases inflammatory cell density infiltration early after injury. A full thickness 1.5×1.5 cm-square wound was created on the dorsum of 8–9 wk old C57BL/6J-m+Leprdb mice (db/db). Wounds were treated daily with 300μl of either normal saline (0.9% NaCl) or 10−9M SP for seven days. Three wounds from each group were harvested at 2,3,7,14, and 28 days. Samples underwent enzymatic digestion and were incubated with fluorescent-labeled antibodies. Using flow cytometry, cellular content and density for each sample was derived. Masson Trichrome stained histology specimens were prepared to confirm results. Cell density in the SP-treated wounds (11.3×107 cells/gram tissue, SD +/−1.5×107) was greater than in NaCl-treated wounds (7×107 cells/gram tissue, SD +/−2.3×107, p<.05) at day 7 post-wounding. Substance P significantly increased the density of leukocytes (2.1×107, SD +/−3.6×106 vs. 1.8×107, SD+/−4.9×105, p<.02) 3 days after wounding and the density of macrophages (2.9 ×107, SD+/−7.5×106 vs. 1.3×107, SD+/−1.4×106, p<.05) 7 days after wounding. There were no significant differences in endothelial cell, leukocyte or macrophage density at later time points. Topical SP treatment increases early inflammatory density in the healing wounds of db/db mice. These data support a role for nerve-mediated inflammation in cutaneous wound repair. PMID:18638272

  11. Arrest of cytoplasmic streaming induces algal proliferation in green paramecia.

    PubMed

    Takahashi, Toshiyuki; Shirai, Yohji; Kosaka, Toshikazu; Hosoya, Hiroshi

    2007-01-01

    A green ciliate Paramecium bursaria, bearing several hundreds of endosymbiotic algae, demonstrates rotational microtubule-based cytoplasmic streaming, in which cytoplasmic granules and endosymbiotic algae flow in a constant direction. However, its physiological significance is still unknown. We investigated physiological roles of cytoplasmic streaming in P. bursaria through host cell cycle using video-microscopy. Here, we found that cytoplasmic streaming was arrested in dividing green paramecia and the endosymbiotic algae proliferated only during the arrest of cytoplasmic streaming. Interestingly, arrest of cytoplasmic streaming with pressure or a microtubule drug also induced proliferation of endosymbiotic algae independently of host cell cycle. Thus, cytoplasmic streaming may control the algal proliferation in P. bursaria. Furthermore, confocal microscopic observation revealed that a division septum was formed in the constricted area of a dividing paramecium, producing arrest of cytoplasmic streaming. This is a first report to suggest that cytoplasmic streaming controls proliferation of eukaryotic cells. PMID:18159235

  12. High cell-surface density of HER2 deforms cell membranes.

    PubMed

    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

  13. Interleukin-8 in Hodgkin's disease. Preferential expression by reactive cells and association with neutrophil density.

    PubMed Central

    Foss, H. D.; Herbst, H.; Gottstein, S.; Demel, G.; Araujó, I.; Stein, H.

    1996-01-01

    Hodgkin's disease (HD) shows rare neoplastic Hodgkin and Reed-Sternberg cells embedded in an abundant reactive infiltrate containing, among other cell types, neutrophilic granulocytes. Interleukin (IL)-8 is chemotactic for neutrophils. The expression of IL-8 was tested by in situ hybridization with 35S-labeled IL-8-specific RNA probes on 38 cases of HD. Reactive lesions, non-Hodgkin's lymphomas of B and T phenotype, and Langerhans cell histiocytosis served as controls. IL-8 expression was observed in Hodgkin and Reed-Sternberg cells in 3 of 33 cases of classical HD and in reactive cells in 20 of 33 HD cases as evidenced by combined isotopic in situ hybridization and immunohistology for the demonstration of cell-type-characteristic antigens or enzyme histochemistry for chloroacetate esterase. IL-8-positive cells were more numerous in cases of nodular sclerosing HD as compared with the mixed cellularity histotype (P = 0.01). The number of IL-8-positive cells and the density of neutrophils were positively correlated (P < 0. 01). In 5 cases of lymphocyte-predominant HD, IL-8 expression was not displayed. Non-Hodgkin's lymphoma cases contained IL-8 transcripts only in 1 of 23 cases in sparse reactive cells. In 4 of 7 cases of Langerhans cell histiocytosis, IL-8-specific signals were displayed in S100-negative cells. In conclusion, IL-8 expression in HD is largely confined to reactive cells and associated with infiltration by neutrophils. Elaboration of other cytokines by Hodgkin and Reed-Sternberg cells and reactive cells may explain the frequent expression of this cytokine in HD, particularly in the nodular sclerosing type. Images Figure 1 Figure 2 PMID:8644863

  14. A device to facilitate preparation of high-density neural cell cultures in MEAs.

    PubMed

    Mok, S Y; Lim, Y M; Goh, S Y

    2009-05-15

    A device to facilitate high-density seeding of dissociated neural cells on planar multi-electrode arrays (MEAs) is presented in this paper. The device comprises a metal cover with two concentric cylinders-the outer cylinder fits tightly on to the external diameter of a MEA to hold it in place and an inner cylinder holds a central glass tube for introducing a cell suspension over the electrode area of the MEA. An O-ring is placed at the bottom of the inner cylinder and the glass tube to provide a fluid-tight seal between the glass tube and the MEA electrode surface. The volume of cell suspension in the glass tube is varied according to the desired plating density. After plating, the device can be lifted from the MEA without leaving any residue on the contact surface. The device has enabled us to increase and control the plating density of neural cell suspension with low viability, and to prepare successful primary cultures from cryopreserved neurons and glia. The cultures of cryopreserved dissociated cortical neurons that we have grown in this manner remained spontaneously active over months, exhibited stable development and similar network characteristics as reported by other researchers. PMID:19428539

  15. 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

  16. 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

  17. Mast cell density in oral submucous fibrosis: a possible role in pathogenesis

    PubMed Central

    Pujari, Ravikumar; Vidya, N

    2013-01-01

    Objective Oral submucous fibrosis (OSMF) is a premalignant condition of oral cavity characterized by inflammation and progressive mucosal fibrosis. It has questionable pathogenesis. Mast cells (MC) have been associated with variety of inflammatory and fibrotic conditions, but little is known about their role in OSMF. Mast cells have been studied in normal gingiva, chronic inflammatory gingivitis, desquamative gingivitis, lichen planus, OSMF and oral cancer. Mast cells exhibit phenotypic plasticity. There is variation in the mast cell mediators with the change in the microenvironment, which makes the study of this cell in various diseases interesting. Study design A retrospective study was conducted to find possible correlation between MC in 25 cases of OSF, 10 cases of oral squamous cell carcinoma (OSCC) and 10 cases of normal buccal mucosa by means of acidified toluidine blue staining method. Results The density of MC increased with disease progression. The densities of MC were significantly higher in OSMF than in normal buccal mucosa (p=0.001). The average numbers of MCs per square millimeter were 25, 49.50, 53.25 & 55.25 respectively. Conclusion The results suggest that MC have a definite role in initiation and progression of OSMF. PMID:23559902

  18. 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. PMID:22629336

  19. Effects of Laser Peripheral Iridotomy on Corneal Endothelial Cell Density and Cell Morphology in Primary Angle Closure Suspect Subjects

    PubMed Central

    Jamali, Hossein; Jahanian, Sara; Gharebaghi, Reza

    2016-01-01

    Purpose: To evaluate the effects of prophylactic laser peripheral iridotomy on corneal endothelial cell density and cell morphology in subjects with primary angle closure suspect (PACS) within a one-year follow-up period. Methods: In this quasi-experimental prospective study, from June 2012 to November 2013, thirty-five PACS eyes underwent laser peripheral iridotomy at clinics affiliated to Shiraz University of Medical Sciences, Shiraz, Iran. After obtaining informed consent, specular microscopy was performed at baseline and at 3-month, 6-month and 12-month follow-up visits. Central, nasal and temporal endothelial cell counts and cell morphology were evaluated via non-contact specular microscopy. Results: The mean subject age was 53.4 ± 7.9 years, and the majority of subjects were women (88.2%). The mean central corneal endothelial cell count prior to laser peripheral iridotomy was 2528 ± 119.2, and this value changed to 2470 ± 175.9, 2425 ± 150.6, and 2407 ± 69.02 at the 3-month, 6-month, and 12-month follow-up visits, respectively; these differences did not reach statistical significance. Additionally, the changes in the number of cells, the hexagonality of cells, and the coefficient of variation (CV) in the central, nasal, and temporal areas were not significant. Conclusion: In PACS eyes, we did not find a decline in corneal endothelial cell density or a change in cell morphological characteristics, including cell hexagonality and CV, in the central, nasal, and temporal regions of the cornea in any of our subjects over a one-year follow-up period.

  20. Peak density, size and regional distribution of ganglion cells in the retina of the fur seal Callorhinus ursinus.

    PubMed

    Mass, A M; Supin, A Y

    1992-01-01

    The total number, size, topographic distribution and peak density of ganglion cells were studied in retinal wholemounts of the fur seal, Callorhinus ursinus. The cell distribution showed a distinct zone of high ganglion cell density. It was located in the temporal retinal quadrant, near the horizontal meridian, 10-12 mm (25-31 degrees) from the optic disk. The peak cell density in this zone was 812-1332 cells/mm2 (mean 1053 cells/mm2), i.e. 125-205 cells/deg2 (mean 162 cells/deg2). These data predict a retinal resolution of 5.6-7.1 cycle/deg. The ganglion cell soma size ranged from 10 to 50 microns. Cell size histograms were bimodal in shape with modes below and above 30 microns. PMID:1555111

  1. 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.

  2. Conditional Density-based Analysis of T cell Signaling in Single Cell Data

    PubMed Central

    Krishnaswamy, Smita; Spitzer, Matthew H.; Mingueneau, Michael; Bendall, Sean C; Litvin, Oren; Stone, Erica; Pe’er, Dana; Nolan, Garry P

    2015-01-01

    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, like 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 MAP kinase (ERK2), which showed stronger influence of pERK on pS6 (phosphorylated-ribosomal protein S6), in naïve cells compared to antigen-exposed cells, as predicted. We demonstrate that by using cell-to-cell variation inherent in single cell data, we can algorithmically derive response functions underlying molecular circuits and drive the understanding of how cells process signals. PMID:25342659

  3. 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.

  4. 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

  5. Density enhanced phosphatase-1 down-regulates urokinase receptor surface expression in confluent endothelial cells

    PubMed Central

    Brunner, Patrick M.; Heier, Patricia C.; Mihaly-Bison, Judit; Priglinger, Ute; Binder, Bernd R.

    2011-01-01

    VEGF165, the major angiogenic growth factor, is known to activate various steps in proangiogenic endothelial cell behavior, such as endothelial cell migration and invasion, or endothelial cell survival. Thereby, the urokinase-type plasminogen activator (uPA) system has been shown to play an essential role not only by its proteolytic capacities, but also by induction of intracellular signal transduction. Therefore, expression of its cell surface receptor uPAR is thought to be an essential regulatory mechanism in angiogenesis. We found that uPAR expression on the surface of confluent endothelial cells was down-regulated compared with subconfluent proliferating endothelial cells. Regulation of uPAR expression was most probably affected by extracellular signal-regulated kinase 1/2 (ERK1/2) activation, a downstream signaling event of the VEGF/VEGF-receptor system. Consistently, the receptor-like protein tyrosine phosphatase DEP-1 (density enhanced phosphatase-1/CD148), which is abundantly expressed in confluent endothelial cells, inhibited the VEGF-dependent activation of ERK1/2, leading to down-regulation of uPAR expression. Overexpression of active ERK1 rescued the DEP-1 effect on uPAR. That DEP-1 plays a biologic role in angiogenic endothelial cell behavior was demonstrated in endothelial cell migration, proliferation, and capillary-like tube formation assays in vitro. PMID:21304107

  6. Growth control of prostatic carcinoma cells in serum-free media: interrelationship of hormone response, cell density, and nutrient media.

    PubMed Central

    Kaighn, M E; Kirk, D; Szalay, M; Lechner, J F

    1981-01-01

    Two established prostatic carcinoma cell lines have been grown in long-term culture in a defined medium (PFMR-4) free of serum, hormones, or growth factors. Growth of both lines in serum-free medium was population dependent. This cell-density requirement could be replaced by mitomycin C-inactivated feeder cells, homologous conditioned medium, or fetal bovine serum, but not by hormones or growth factors. The cells responded to these factors only at high density. The nature of this hormonal response was dependent on the kind of basal nutrient medium used. Growth in PFMR-4 with added insulin was more rapid than that in DME/F12 medium with any combination of hormones or growth factors and was substantially greater than growth in DME/F12 medium with insulin alone. The results demonstrate that whereas these two prostatic carcinoma lines (PC-3 and DU 145) do not require hormones for survival or growth, they do respond to certain hormones under appropriate conditions. These conditions include both the type of basal nutrient medium used and the population density. PMID:7029542

  7. 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. PMID:26141781

  8. [THE BECOMING IN PHYLOGENESIS OF TRANSFER IN INTERCELLULAR MEDIUM AND ACTIVE ABSORPTION OF POLYENOIC FATTY ACIDS BY CELLS SEQUENTIALLY OF HIGH DENSITY LIPOPROTEINS, LOW DENSITY LIPOPROTEINS AND HIGH DENSITY APOE-LIPOPROTEINS].

    PubMed

    Titov, V N

    2015-06-01

    After more than half-century of different conceptions, the theory of general pathology was used to substantiate that all lipoproteins are bi-layer:lipid by their structure. The main function of high density lipoproteins as of all lipoproteins is transfer of fatty acids to cells and only in second turn taking away of spirit cholesterol from cells. At the stages of phylogenesis high density lipoproteins, low density lipoproteins and very low density lipoproteins began to function in a subsequent way. The fatty acids were transferred by low density lipoproteins in polar lipids at passive absorption by cells. Later on, lipoproteins transfer fatty acids in non-polar ethers with spirits glycerin and spirit cholesterol. The cells absorb them by receptor endocytosis. The hepatocytes secret in blood palmitic, oleic, linoleic and linoleic very low density lipoproteins. The palmitic and oleic very low density lipoproteins absorb physiologically insulin-dependent cells apoE/B-100 = endocytosis. The linoleic and linoleic very low density lipoproteins after transition of polyethers cholesterol from high density lipoproteins turn into low density lipoproteins. The cells absorb them by apoB-100 = endocytosis. The formation of chylomicrons occurs in blood and hepatocytes absorb them by the way of apoB/E-48 = endocytosis. The absorption of poly-unsaturated fatty acids by cells with apoB-100 = endocytosis form sensitivity of animals to exogenous hyper spirit cholesterol and absorption of poly-unsaturated fatty acids by apoE/A-I = receptors form corresponding resistance. The ApoE in lipoproteins form cooperative ligands--apoE/B-48 for chylomicrons, apoE/B-100 for very low density lipoproteins and apoE/A-I for high density lipoproteins. The chylomicrons in blood form apoB-48 from complexes of triglycerides secreted by enterocytes. These views change conceptions of pathogenesis and prevention of atherosclerosis, metabolic syndrome and resistance to insulin whose pathogenesis is unified

  9. Maintenance of algal endosymbionts in Paramecium bursaria: a simple model based on population dynamics.

    PubMed

    Iwai, Sosuke; Fujiwara, Kenji; Tamura, Takuro

    2016-09-01

    Algal endosymbiosis is widely distributed in eukaryotes including many protists and metazoans, and plays important roles in aquatic ecosystems, combining phagotrophy and phototrophy. To maintain a stable symbiotic relationship, endosymbiont population size in the host must be properly regulated and maintained at a constant level; however, the mechanisms underlying the maintenance of algal endosymbionts are still largely unknown. Here we investigate the population dynamics of the unicellular ciliate Paramecium bursaria and its Chlorella-like algal endosymbiont under various experimental conditions in a simple culture system. Our results suggest that endosymbiont population size in P. bursaria was not regulated by active processes such as cell division coupling between the two organisms, or partitioning of the endosymbionts at host cell division. Regardless, endosymbiont population size was eventually adjusted to a nearly constant level once cells were grown with light and nutrients. To explain this apparent regulation of population size, we propose a simple mechanism based on the different growth properties (specifically the nutrient requirements) of the two organisms, and based from this develop a mathematical model to describe the population dynamics of host and endosymbiont. The proposed mechanism and model may provide a basis for understanding the maintenance of algal endosymbionts. PMID:26625979

  10. In vivo bone formation by human bone marrow cells: effect of osteogenic culture supplements and cell densities.

    PubMed

    Mendes, S C; Van Den Brink, I; De Bruijn, J D; Van Blitterswijk, C A

    1998-12-01

    Bone marrow is known to contain a population of osteoprogenitor cells that can go through complete differentiation when cultured in a medium containing appropriate bioactive factors. In this study, porous particles of a calcium phosphate material were seeded with adult human bone marrow cells in the second passage. After an additional culture period of 1 wk in the particles, these hybrid constructs were subcutaneouslly implanted in nude mice with a survival period of 4 wk. The cell seeding densities range from 0-200 000 cells per particle and the cell culture system was designed to investigate the single and combined effects of dexamethasone and recombinant human bone morphogenetic protein 2 (rhBMP-2). The hybrid "material/tissue" constructs were processed for histology and the amount of de novo bone formation was quantified, for each culture condition, by histomorphometric techniques. The relative percentage of mineralized bone formation reached a maximal value of 19.77+/-5.06, for samples cultured in the presence of rhBMP-2 and with a seeding density of 200 000 cells/particle, compared to 0.52+/-0.45 for samples in which no cells had been cultured and had been incubated in culture medium supplemented with Dex and rhBMP-2. For the tested conditions and for the low cell numbers used in this study, rhBMP-2 proved to be an essential bioactive factor to obtain in vivo bone formation by our culture system. The results from this study prove the potential of cultured adult human bone marrow cells to initiate and accelerate de novo bone formation after transplantation into an ectopic site. PMID:15348953

  11. 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

  12. Two-dimensional helium density profiles in a GEC RF Reference Cell

    SciTech Connect

    Greenberg, K.E.; Hebner, G.A.

    1992-12-01

    Optical absorption spectroscopy was used to measure 2{sup 3}S and 2{sup 1}S metastable densities in 13.56-MHz, helium discharges. Apertured light from a helium Geisler tube was expanded, collimated, and directed into a GEC Reference Cell through an 8-in viewport (6 inches clear optical access). The light exiting the cell through a similar viewport was focused and imaged, through a 0.5-mm aperture and bandpass filter, onto the intensifier of a CCD-array detector system. Spatially resolved absorption profiles (with approximately one millimeter resolution), extending from the center of the discharge to the edge of the viewport, were recorded for 1- to 15-W discharges at 0.5 and 1.0 Torr pressure. At 1.0 Torr, the metastable density profiles were peaked near the powered electrode with the 2{sup 1}S profile reaching a maximum closer to the electrode than the 2{sup 3}S profile. In addition, the metastable density dropped rapidly outside of the discharge region. At 0.5 Torr pressure, the metastable profiles were symmetric, peaking at the midpoint between the electrodes. Total metastable densities were on the order of 10{sup 11}/cm{sup 3} for a 1-Torr discharge.

  13. 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. PMID:21336955

  14. 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. PMID:27519944

  15. Estimation of localized current anomalies in polymer electrolyte fuel cells from magnetic flux density measurements

    NASA Astrophysics Data System (ADS)

    Nara, Takaaki; Koike, Masanori; Ando, Shigeru; Gotoh, Yuji; Izumi, Masaaki

    2016-05-01

    In this paper, we propose novel inversion methods to estimate defects or localized current anomalies in membrane electrode assemblies (MEAs) in polymer electrolyte fuel cells (PEFCs). One method is an imaging approach with L1-norm regularization that is suitable for estimation of focal anomalies compared to Tikhonov regularization. The second is a complex analysis based method in which multiple pointwise current anomalies can be identified directly and algebraically from the measured magnetic flux density.

  16. 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. PMID:18442443

  17. 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.

  18. 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. PMID:23079413

  19. The Ca2+/Mn2+-transporting SPCA2 pump is regulated by oxygen and cell density in colon cancer cells.

    PubMed

    Jenkins, James; Papkovsky, Dmitri B; Dmitriev, Ruslan I

    2016-08-15

    The mammalian SPCA1 and SPCA2 ATPases localize in membranes of the secretory pathway and transport ions of Ca(2+) and Mn(2+) The role of tissue-specific SPCA2 isoform, highly expressed in lungs, mammary gland and gastrointestinal tract, is poorly understood. To elucidate the function of SPCA2, we studied human colon cancer HCT116 cells, grown under ambient and decreased O2 levels. We found that in contrast with other Ca(2+)-ATPase isoforms the expression of SPCA2 was up-regulated under hypoxia (3% O2), in both adherent (2D) and spheroid (3D) cultures. In spheroids, experiencing lowest O2 levels (30-50 μM, measured by phosphorescence lifetime imaging microscopy), we observed lower staining with reactive oxygen species (ROS)-specific fluorescent probe, which correlated with increased SPCA2. However, SPCA2 expression was up-regulated in cells exposed to reactive oxygen and nitrogen species donors, and when grown at higher density. We noticed that the culture exposed to hypoxia showed overall increase in S phase-positive cells and hypothesized that SPCA2 up-regulation under hypoxia can be linked to Mn(2+)-dependent cell cycle arrest. Consequently, we found that SPCA2-transfected cells display a higher number of cells entering S phase. Altogether, our results point at the important role of SPCA2 in regulation of cell cycle in cancer cells. PMID:27316461

  20. 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. PMID:25682049

  1. 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.

  2. Influence of zeta potential on the flocculation of cyanobacteria cells using chitosan modified soil.

    PubMed

    Li, Liang; Zhang, Honggang; Pan, Gang

    2015-02-01

    Using chitosan modified soil to flocculate and sediment algal cells has been considered as a promising strategy to combat cyanobacteria blooms in natural waters. However, the flocculation efficiency often varies with algal cells with different zeta potential (ZP) attributed to different growth phases or water conditions. This article investigated the relationship between ZP of Microcystis aeruginosa and its influence to the flocculation efficiency using chitosan modified soil. Results suggested that the optimal removal efficiency was obtained when the ZP was between -20.7 and -6.7 mV with a removal efficiency of more than 80% in 30 min and large floc size of >350 μm. When the algal cells were more negatively charged than -20.7 mV, the effect of chitosan modified soil was depressed (<60%) due to the insufficient charge density of chitosan to neutralize and destabilize the algal suspension. When the algal cells were less negative than -6.7 mV or even positively charged, a small floc size (<120 μm) was formed, which may be difficult to sink under natural water conditions. Therefore, manipulation of ZP provided a viable tool to improve the flocculation efficiency of chitosan modified soil and an important guidance for practical engineering of cyanobacteria bloom control. PMID:25662238

  3. Reactor-Scale Cultivation of the Hyperthermophilic Methanarchaeon Methanococcus jannaschii to High Cell Densities

    PubMed Central

    Mukhopadhyay, Biswarup; Johnson, Eric F.; Wolfe, Ralph S.

    1999-01-01

    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 ∼0.5 to ∼7.5 g of packed wet cells (∼1.8 g dry cell mass) under autotrophic growth conditions and to ∼8.5 g of packed wet cells (∼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 μM 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 H2S supply. But, for the optimal performance of a reactor culture, an addition of Se to a final concentration of 50 to 100 μM 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. PMID:10543823

  4. 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. PMID:15162733

  5. 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.

  6. 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.

  7. 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. PMID:25930117

  8. 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

  9. 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.

  10. 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. PMID:26411559

  11. Herbivore Recolonization Rate Influences Light and Nutrient Effects on Algal Based Stream Ecosystems

    NASA Astrophysics Data System (ADS)

    Taulbee, K.

    2005-05-01

    The dynamics of algal based ecosystems are influenced by both resource availability and herbivory. Following a disturbance, the relative importance of top down versus bottom up regulation of algal dynamics in a particular system depends on both herbivore immigration rates and local resource availabilities. The effects of herbivore recolonization and resource availability on the recovery dynamics of algal ecosystems following a disturbance were investigated during two field experiments conducted in 24 in situ stream channels in Convict Creek, California. In each experiment, light and nutrients were cross-classified in a 6x2 factorial design, with 2 replicates per treatment. Initial algal and invertebrate densities were low. Using upstream drift nets of different mesh sizes, herbivore immigration was restricted in one experiment and unrestricted in a second experiment. The relative importance of herbivore versus resource regulation of algae was influenced by herbivore immigration. When immigration was restricted, as might occur following a severe disturbance, algae were more closely regulated by resource availability. In contrast, when herbivore immigration was not restricted, algae were regulated by both resource availability and herbivory. Finally, the effects of light and nutrients on algae were interactive when immigration was restricted, but not when immigration was unrestricted.

  12. 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

  13. Inducible expression of calreticulin-N58 in Pichia pastoris by high density cell culture.

    PubMed

    Su, D X; Zhang, A L; Yi, G H; Liu, Z W; Luo, J X; Rao, L Y; Zhang, T Y; Zhou, Z J

    2011-11-01

    Calreticulin-N58 (CRT-N58), an active fragment of calreticulin with anti-angiogenesis activity, was expressed in P. pastoris by high density cell culture. Calreticulin-N58 DNA was synthesized by PCR and cloned to plasmid pPIC9 K resulting in the plasmid pPIC9 K-crt-N58 which was then transformed into P. pastoris GS115. The fermentation was carried out in a 50 l bioreactor with 20 l modified growth medium recommended by Invitrogen at 30°C. The cells were first grown in glycerol-PTM4 trace salts for 24 h. When the cell density was grown to A(600) = 135, methanol-PTM4 trace salts was added to induce the expression of calreticulin-N58. During the fermentation, dissolved oxygen level was maintained at 20-30%, pH was controlled at 5 by adding 7 M NH(4)OH. After 52 h of induction, the yield of secreted calreticulin-N58 was 70 mg/l and biomass growth was 293 as measured by absorption of 600 nm. The secreted calreticulin-N58 was purified to a purity of 100% by the use of SP-Sepharose FF ion-exchange chromatography (Pharmacia Biotech. NJ, USA) and desalted with ultrafiltration device (Millipore, Bedford, MA, USA). The recombinant calreticulin-N58 induced endothelial cell apoptosis and inhibited the angiogenesis on the CAM. PMID:21181274

  14. Removal of algal blooms from freshwater by the coagulation-magnetic separation method.

    PubMed

    Liu, Dan; Wang, Peng; Wei, Guanran; Dong, Wenbo; Hui, Franck

    2013-01-01

    This research investigated the feasibility of changing waste into useful materials for water treatment and proposed a coagulation-magnetic separation technique. This technique was rapid and highly effective for clearing up harmful algal blooms in freshwater and mitigating lake eutrophication. A magnetic coagulant was synthesized by compounding acid-modified fly ash with magnetite (Fe(3)O(4)). Its removal effects on algal cells and dissolved organics in water were studied. After mixing, coagulation, and magnetic separation, the flocs obtained from the magnet surface were examined by SEM. Treated samples were withdrawn for the content determination of chlorophyll-a, turbidity, chemical oxygen demand (COD), total nitrogen, and total phosphorus. More than 99 % of algal cells were removed within 5 min after the addition of magnetic coagulant at optimal loadings (200 mg L(-1)). The removal efficiencies of COD, total nitrogen, and phosphorus were 93, 91, and 94 %, respectively. The mechanism of algal removal explored preliminarily showed that the magnetic coagulant played multiple roles in mesoporous adsorption, netting and bridging, as well as high magnetic responsiveness to a magnetic field. The magnetic-coagulation separation method can rapidly and effectively remove algae from water bodies and greatly mitigate eutrophication of freshwater using a new magnetic coagulant. The method has good performance, is low cost, can turn waste into something valuable, and provides reference and directions for future pilot and production scale-ups. PMID:22767355

  15. 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

  16. 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

  17. Control of algal production in a high rate algal pond: investigation through batch and continuous experiments.

    PubMed

    Derabe Maobe, H; Onodera, M; Takahashi, M; Satoh, H; Fukazawa, T

    2014-01-01

    For decades, arid and semi-arid regions in Africa have faced issues related to water availability for drinking, irrigation and livestock purposes. To tackle these issues, a laboratory scale greywater treatment system based on high rate algal pond (HRAP) technology was investigated in order to guide the operation of the pilot plant implemented in the 2iE campus in Ouagadougou (Burkina Faso). Because of the high suspended solids concentration generally found in effluents of this system, the aim of this study is to improve the performance of HRAPs in term of algal productivity and removal. To determine the selection mechanism of self-flocculated algae, three sets of sequencing batch reactors (SBRs) and three sets of continuous flow reactors (CFRs) were operated. Despite operation with the same solids retention time and the similarity of the algal growth rate found in these reactors, the algal productivity was higher in the SBRs owing to the short hydraulic retention time of 10 days in these reactors. By using a volume of CFR with twice the volume of our experimental CFRs, the algal concentration can be controlled during operation under similar physical conditions in both reactors. PMID:24960016

  18. 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.

  19. 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.

  20. Combinational effect of matrix elasticity and alendronate density on differentiation of rat mesenchymal stem cells.

    PubMed

    Jiang, Pengfei; Mao, Zhengwei; Gao, Changyou

    2015-06-01

    Differentiation of mesenchymal stem cells (MSCs) is regulated by multivariate physical and chemical signals in a complicated microenvironment. In this study, polymerizable double bonds (GelMA) and osteo-inductive alendronate (Aln) (Aln-GelMA) were sequentially grafted onto gelatin molecules. The biocompatible hydrogels with defined stiffness in the range of 4-40 kPa were prepared by using polyethylene glycol diacrylate (PEGDA) as additional crosslinker. The Aln density was adjusted from 0 to 4 μM by controlling the ratio between the GelMA and Aln-GelMA. The combinational effects of stiffness and Aln density on osteogenic differentiation of MSCs were then studied in terms of ALP activity, collagen type I and osteocalcin expression, and calcium deposition. The results indicated that the stiffness and Aln density could synergistically improve the expression of all these osteogenesis markers. Their osteo-inductive effects are comparable to some extent, and high Aln density could be more effective than the stiffness. PMID:25805109

  1. Estimating the neutrally buoyant energy density of a Rankine-cycle/fuel-cell underwater propulsion system

    NASA Astrophysics Data System (ADS)

    Waters, Daniel F.; Cadou, Christopher P.

    2014-02-01

    A unique requirement of underwater vehicles' power/energy systems is that they remain neutrally buoyant over the course of a mission. Previous work published in the Journal of Power Sources reported gross as opposed to neutrally-buoyant energy densities of an integrated solid oxide fuel cell/Rankine-cycle based power system based on the exothermic reaction of aluminum with seawater. This paper corrects this shortcoming by presenting a model for estimating system mass and using it to update the key findings of the original paper in the context of the neutral buoyancy requirement. It also presents an expanded sensitivity analysis to illustrate the influence of various design and modeling assumptions. While energy density is very sensitive to turbine efficiency (sensitivity coefficient in excess of 0.60), it is relatively insensitive to all other major design parameters (sensitivity coefficients < 0.15) like compressor efficiency, inlet water temperature, scaling methodology, etc. The neutral buoyancy requirement introduces a significant (˜15%) energy density penalty but overall the system still appears to offer factors of five to eight improvements in energy density (i.e., vehicle range/endurance) over present battery-based technologies.

  2. 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.

  3. Recognizing harmful algal bloom based on remote sensing reflectance band ratio

    NASA Astrophysics Data System (ADS)

    Bresciani, Mariano; Giardino, Claudia; Bartoli, Marco; Tavernini, Silvia; Bolpagni, Rossano; Nizzoli, Daniele

    2011-01-01

    We present a band ratio algorithm based on remote sensing reflectance (RRS) data to detect an algal bloom composed of cyanobacteria (Planktothrix spp.) and chrysophytes in Lake Idro, a small meso-eutrophic lake situated in the subalpine region (northern Italy). The bloom started around the first week of September 2010 and persisted for about 1 month, with highest mean chlorophyll-a concentrations (17.5 +/- 1.6 mgm-3) and phytoplankton cellular density (7,250,000 cell.l-1) measured on September 14, 2010. RRS data obtained from in situ measurements were first investigated to select the diagnostic wavelengths (i.e., 560 and 620 nm) of both phycoerythrin (present in the Planktothrix spp.) and other pigments (e.g., fucoxanthin, common to several species of chrysophyte). Testing the algorithm on RRS data derived from atmospherically corrected image data showed the ability of the medium resolution imaging spectrometer (MERIS) to detect the bloom also. The results demonstrate that a combination of in situ and MERIS data is a valuable tool to monitor the extent and duration of phytoplankton blooms.

  4. 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

  5. Expression of Endoglin (CD-105) and Microvessel Density in Oral Dysplasia and Squamous Cell Carcinoma

    PubMed Central

    SR, Shashikanth; BNVS, Satish

    2014-01-01

    Objective: To assess the expression of Endoglin (CD-105) and Microvessel Density in clinically normal oral mucosa of non-tobacco and tobacco habituated patients & also histopathologically confirmed cases of oral squamous cell carcinoma (OSCC) patients. Materials and Methods: Twenty cases of clinically normal oral mucosa with tobacco habituation in the form of chewing or smoking, 20 histopathologically confirmed cases of OSCC and twelve normal healthy oral mucosal cases without tobacco habituation in any form, served as control group, were immunohistochemically analysed for expression of Endoglin (CD-105). Chi-square test is used to determine statistical analysis and significance. Result & Conclusion: The finding of 65% of Endoglin CD - 105 positivity and microvessel density (MVD) in the mucosal specimens of tobacco users may be attributed as neoangiogenesis or angiogenic squamous dysplasia like phenomenon occurring as important pathological biomarker preceding oral cancer development, and may therefore be useful as a predictive marker of malignancy. PMID:25386532

  6. Low-density open-cell foams in the NiTi system

    NASA Astrophysics Data System (ADS)

    Grummon, David S.; Shaw, John A.; Gremillet, Antoine

    2003-04-01

    It is shown that open-cell metallic foams having very low density, and that display martensite transformations required for shape memory and superelastic behavior, can be fabricated using a powder-metallurgy technique. Results are presented on experiments in which a polymeric precursor foam was coated with an equiatomic NiTi powder slurry and subsequently sintered to yield foams with relative densities as low as 0.039. Although contaminated with interstitial impurities, they displayed unambiguous calorimetric signature of the B2→B19' transformation. The results are of considerable significance to potential applications requiring ultralightweight structures with the unusual dissipative and strain-recovery properties of NiTi shape-memory materials.

  7. 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.

  8. 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

  9. Imaging the local forward current density of solar cells by dynamical precision contact thermography

    SciTech Connect

    Breitenstein, O.; Eberhardt, W.; Iwig, K.

    1994-12-31

    In spite of many techniques of measuring the local lifetime or the local short circuit current, no non-destructive technique has been available for imaging the local forward current density, which determines the open circuit voltage and the fill factor of solar cells. The authors demonstrate the application of a new analyzing technique, enabling non-destructive shunt hunting in forward direction. A periodical forward current is applied to the cell, and only the dynamical temperature response is measured in contact mode with a resolution below 10 {micro}K. Mechanical scanning of the T-sensor position yields a thermogram with a spatial resolution well below 1 mm and a current density resolution well below 1 mA/cm{sup 2}. First results show that both the edges of solar cells and their interior may have sites of a locally increased forward current. Hot spots measured in reverse bias direction only occasionally coincide with these warm spots measured in forward direction.

  10. Acetate metabolism by Escherichia coli in high-cell-density fermentation.

    PubMed Central

    Kleman, G L; Strohl, W R

    1994-01-01

    Little is known about the cellular physiology of Escherichia coli at high cell densities (e.g., greater than 50 g [dry cell weight] per liter), particularly in relation to the cellular response to different growth conditions. E. coli W3100 cultures were grown under identical physical and nutritional conditions, by using a computer-controlled fermentation system which maintains the glucose concentration at 0.5 g/liter, to high cell densities at pH values of 6.0, 6.5, 7.0, and 7.5. The data suggest a relationship between the pH of the environment and the amount of acetate excreted by the organism during growth. At pH values of 6.0 and 6.5, the acetate reached a concentration of 6 g/liter, whereas at pH 7.5, the acetate reached a concentration of 12 g/liter. Furthermore, at pH values of 6.0 to 7.0, the E. coli culture undergoes a dramatic metabolic switch in which oxygen and glucose consumption and CO2 evolution all temporarily decreased by 50 to 80%, with a concomitant initiation of acetate utilization. After a 30-min pause in which approximately 50% of the available acetate is consumed, the culture recovers and resumes consuming glucose and oxygen and producing acetate and CO2 at preswitch levels. During the switch period, the specific activity of isocitrate lyase typically increases approximately fourfold. PMID:7993084

  11. Metastatic breast cancer cells in lymph nodes increase nodal collagen density

    PubMed Central

    Rizwan, Asif; Bulte, Camille; Kalaichelvan, Anusha; Cheng, Menglin; Krishnamachary, Balaji; Bhujwalla, Zaver M.; Jiang, Lu; Glunde, Kristine

    2015-01-01

    The most life-threatening aspect of breast cancer is the occurrence of metastatic disease. The tumor draining lymph nodes typically are the first sites of metastasis in breast cancer. Collagen I fibers and the extracellular matrix have been implicated in breast cancer to form avenues for metastasis. In this study, we have investigated extracellular matrix molecules such as collagen I fibers in the lymph nodes of mice bearing orthotopic human breast cancer xenografts. The lymph nodes in mice with metastatic MDA-MB-231 and SUM159 tumor xenografts and tumor xenografts grown from circulating tumor cell lines displayed an increased collagen I density compared to mice with no tumor and mice with non-metastatic T-47D and MCF-7 tumor xenografts. These results suggest that cancer cells that have metastasized to the lymph nodes can modify the extracellular matrix components of these lymph nodes. Clinically, collagen density in the lymph nodes may be a good marker for identifying lymph nodes that have been invaded by breast cancer cells. PMID:25950608

  12. 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

    2011-01-01

    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. PMID:21811245

  13. Vertically aligned carbon nanotube electrodes for high current density operating proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Murata, Shigeaki; Imanishi, Masahiro; Hasegawa, Shigeki; Namba, Ryoichi

    2014-05-01

    We successfully developed cathode electrodes for polymer electrolyte membrane fuel cells (PEMFC) that enable operation at high current densities by incorporating vertically aligned carbon nanotubes (CNTs) as the catalyst support; additionally, we prepared 236 cm2 membrane electrodes assemblies (MEAs) for vehicular use. The electrode structure improved the mass transport of reactants, i.e. oxygen, proton, electron and water, in systems performing at a 2.6 A cm-2 current density and 0.6 V with extremely low platinum (Pt) loading at the cathode (0.1 mg cm-2). The improved mass transport caused the 70 mV dec-1 Tafel slope to continue up to 1.0 A cm-2. The mass transport was improved because the pores were continuous, the catalyst support materials did not agglomerate and the catalyst layer made good electrical contact with the microporous layer. Utilizing wavy coil-shaped CNTs was also crucial. These CNTs displayed anti-agglomerative characteristics during the wet manufacturing process and maintained a continuous pore structure framing the layered catalyst structure. Because the CNTs had elastic characteristics, they might fill the space between catalyst and microporous layers to prevent flooding. However, the compressed CNTs in the cells were no longer vertically aligned. Therefore, vertically aligning the nanotubes was important during the MEA manufacturing process but was irrelevant for cell performance.

  14. Kinetic models for astaxanthin production by high cell density mixotrophic culture of the microalga Haematococcus pluvialis.

    PubMed

    Zhang, X W; Gong, X D; Chen, F

    1999-07-01

    High cell density cultivation of Haematococcus pluvialis for astaxanthin production was carried out in batch and fed-batch modes in 3.7-L bioreactors with stepwise increased light intensity control mode. A high cell density of 2.65 g x L(-1) (batch culture) or 2.74 g x L(-1) (fed-batch culture) was obtained, and total astaxanthin production in the fed-batch culture (64.36 mg x L(-1)) was about 20.5% higher than in the batch culture (53.43 mg x L(-1)). An unstructured kinetic model to describe the microalga culture system including cell growth, astaxanthin formation, as well as sodium acetate consumption was proposed. Good agreement was found between the model predictions and experimental data. The models demonstrated that the optimal light intensity for mixotrophic growth of H. pluvialis in batch or fed-batch cultures in a 3.7-L bioreactor was 90-360 micromol x m(-2) x s(-1), and that the stepwise increased light intensity mode could be replaced by a constant light intensity mode. PMID:10455503

  15. Exploration of the antioxidant system and photosynthetic system of a marine algicidal Bacillus and its effect on four harmful algal bloom species.

    PubMed

    Hou, Shaoling; Shu, Wanjiao; Tan, Shuo; Zhao, Ling; Yin, Pinghe

    2016-01-01

    A novel marine bacterium, strain B1, initially showed 96.4% algicidal activity against Phaeocystis globosa. Under this situation, 3 other harmful algal species (Skeletonema costatum, Heterosigma akashiwo, and Prorocentrum donghaiense) were chosen to study the algicidal effects of strain B1, and the algicidal activities were 91.4%, 90.7%, and 90.6%, respectively. To explore the algicidal mechanism of strain B1 on these 4 harmful algal species, the characteristics of the antioxidant system and photosynthetic system were studied. Sensitivity to strain B1 supernatant, enzyme activity, and gene expression varied with algal species, while the algicidal patterns were similar. Strain B1 supernatant increased malondialdehyde contents; decreased chlorophyll a contents; changed total antioxidant and superoxide dismutase activity; and restrained psbA, psbD, and rbcL genes expression, which eventually resulted in the algal cells death. The algicidal procedure was observed using field emission scanning electron microscopy, which indicated that algal cells were lysed and cellular substances were released. These findings suggested that the antioxidant and photosynthetic system of these 4 algal species was destroyed under strain B1 supernatant stress. This is the first report to explore and compare the mechanism of a marine Bacillus against harmful algal bloom species of covered 4 phyla. PMID:26634608

  16. 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. PMID:26771151

  17. LOW-TEMPERATURE, ANODE-SUPPORTED HIGH POWER DENSITY SOLID OXIDE FUEL CELLS WITH NANOSTRUCTURED ELECTRODES

    SciTech Connect

    Anil V. Virkar

    2001-06-21

    A simple, approximate analysis of the effect of differing cathode and anode areas on the measurement of cell performance on anode-supported solid oxide fuel cells, wherein the cathode area is smaller than the anode area, is presented. It is shown that the effect of cathode area on cathode polarization, on electrolyte contribution, and on anode resistance, as normalized on the basis of the cathode area, is negligible. There is a small but measurable effect on anode polarization, which results from concentration polarization. Effectively, it is the result of a greater amount of fuel transported to the anode/electrolyte interface in cases wherein the anode area is larger than the cathode area. Experiments were performed on cells made with differing cathode areas and geometries. Cathodic and anodic overpotentials measured using reference electrodes, and the measured ohmic area specific resistances by current interruption, were in good agreement with expectations based on the analysis presented. At 800 C, the maximum power density measured with a cathode area of {approx}1.1 cm{sup 2} was {approx}1.65 W/cm{sup 2} compared to {approx}1.45 W/cm{sup 2} for cathode area of {approx}2 cm{sup 2}, for anode thickness of {approx}1.3 mm, with hydrogen as the fuel and air as the oxidant. At 750 C, the measured maximum power densities were {approx}1.3 W/cm{sup 2} for the cell with cathode area {approx}1.1 cm{sup 2}, and {approx}1.25 W/cm{sup 2} for the cell with cathode area {approx}2 cm{sup 2}.

  18. 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

  19. Bile acids reduce endocytosis of high-density lipoprotein (HDL) in HepG2 cells.

    PubMed

    Röhrl, Clemens; Eigner, Karin; Fruhwürth, Stefanie; Stangl, Herbert

    2014-01-01

    High-density lipoprotein (HDL) transports lipids to hepatic cells and the majority of HDL-associated cholesterol is destined for biliary excretion. Cholesterol is excreted into the bile directly or after conversion to bile acids, which are also present in the plasma as they are effectively reabsorbed through the enterohepatic cycle. Here, we provide evidence that bile acids affect HDL endocytosis. Using fluorescent and radiolabeled HDL, we show that HDL endocytosis was reduced in the presence of high concentrations of taurocholate, a natural non-cell-permeable bile acid, in human hepatic HepG2 and HuH7 cells. In contrast, selective cholesteryl-ester (CE) uptake was increased. Taurocholate exerted these effects extracellularly and independently of HDL modification, cell membrane perturbation or blocking of endocytic trafficking. Instead, this reduction of endocytosis and increase in selective uptake was dependent on SR-BI. In addition, cell-permeable bile acids reduced HDL endocytosis by farnesoid X receptor (FXR) activation: chenodeoxycholate and the non-steroidal FXR agonist GW4064 reduced HDL endocytosis, whereas selective CE uptake was unaltered. Reduced HDL endocytosis by FXR activation was independent of SR-BI and was likely mediated by impaired expression of the scavenger receptor cluster of differentiation 36 (CD36). Taken together we have shown that bile acids reduce HDL endocytosis by transcriptional and non-transcriptional mechanisms. Further, we suggest that HDL endocytosis and selective lipid uptake are not necessarily tightly linked to each other. PMID:25010412

  20. Endothelial Cell Density to Predict Endothelial Graft Failure After Penetrating Keratoplasty

    PubMed Central

    Lass, Jonathan H.; Sugar, Alan; Benetz, Beth Ann; Beck, Roy W.; Dontchev, Mariya; Gal, Robin L.; Kollman, Craig; Gross, Robert; Heck, Ellen; Holland, Edward J.; Mannis, Mark J.; Raber, Irving; Stark, Walter; Stulting, R. Doyle

    2010-01-01

    Objective To determine whether preoperative and/or postoperative central endothelial cell density (ECD) and its rate of decline postoperatively are predictive of graft failure caused by endothelial decompensation following penetrating keratoplasty to treat a moderate-risk condition, principally, Fuchs dystrophy or pseudophakic corneal edema. Methods In a subset of Cornea Donor Study participants, a central reading center determined preoperative and postoperative ECD from available specular images for 17 grafts that failed because of endothelial decompensation and 483 grafts that did not fail. Results Preoperative ECD was not predictive of graft failure caused by endothelial decompensation (P = .91). However, the 6-month ECD was predictive of subsequent failure (P < .001). Among those that had not failed within the first 6 months, the 5-year cumulative incidence (±95% confidence interval) of failure was 13% (±12%) for the 33 participants with a 6-month ECD of less than 1700 cells/mm2 vs 2%(±3%) for the 137 participants with a 6-monthECDof 2500 cells/mm2 or higher. After 5 years’ follow-up, 40 of 277 participants (14%) with a clear graft had an ECD below 500 cells/mm2. Conclusions Preoperative ECD is unrelated to graft failure from endothelial decompensation, whereas there is a strong correlation of ECD at 6 months with graft failure from endothelial decompensation. A graft can remain clear after 5 years even when the ECD is below 500 cells/mm2. PMID:20065219

  1. High energy density proton exchange membrane fuel cell with dry reactant gases

    SciTech Connect

    Srinivasan, S.; Gamburzev, S.; Velev, O.A.

    1996-12-31

    Proton exchange membrane fuel cells (PEMFC) require careful control of humidity levels in the cell stack to achieve a high and stable level of performance. External humidification of the reactant gases, as in the state-of-the-art PEMFCs, increases the complexity, the weight, and the volume of the fuel cell power plant. A method for the operation of PEMFCs without external humidification (i.e., self-humidified PEMFCs) was first developed and tested by Dhar at BCS Technology. A project is underway in our Center to develop a PEMFC cell stack, which can work without external humidification and attain a performance level of a current density of 0.7 A/cm{sup 2} at a cell potential of 0.7 V, with hydrogen/air as reactants at 1 atm pressure. In this paper, the results of our efforts to design and develop a PEMFC stack requiring no external humidification will be presented. This paper focuses on determining the effects of type of electrodes, the methods of their preparation, as well as that of the membrane and electrode assembly (MEA), platinum loading and types of electrocatalyst on the performance of the PEMFC will be illustrated.

  2. High power density from Pt thin film electrodes based microbial fuel cell.

    PubMed

    Sharma, Tushar; Reddy, A Leela Mohana; Chandra, T S; Ramaprabhu, S

    2008-08-01

    Microbial Fuel Cells (MFC) are robust devices capable of taping biological energy, converting sugars into potential sources of energy. Persistent efforts are directed towards increasing power output. However, they have not been researched to the extent of making them competitive with chemical fuel cells. The power generated in a dual-chamber MFC using neutral red (NR) as the electron mediator has been previously shown to be 152.4 mW/m2 at 412.5 mA/m2 of current density. In the present work we show that Pt thin film coated carbon paper as electrodes increase the performance of a microbial fuel cell compared to conventionally employed electrodes. The results obtained using E. coli based microbial fuel cell with methylene blue and neutral red as the electron mediator, potassium ferricyanide in the cathode compartment were systematically studied and the results obtained with Pt thin film coated over carbon paper as electrodes were compared with that of graphite electrodes. Platinum coated carbon electrodes were found to be better over the previously used for microbial fuel cells and at the same time are cheaper than the preferred pure platinum electrodes. PMID:19049189

  3. Ceruloplasmin enhances smooth muscle cell- and endothelial cell-mediated low density lipoprotein oxidation by a superoxide-dependent mechanism

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, C. K.; Ehrenwald, E.; Fox, P. L.

    1996-01-01

    Cultured vascular smooth muscle cells (SMC) and endothelial cells (EC) stimulate low density lipoprotein (LDL) oxidation by free radical-mediated, transition metal-dependent mechanisms. The physiological source(s) of metal ions is not known; however, purified ceruloplasmin, a plasma protein containing 7 coppers, oxidizes LDL in vitro. We now show that ceruloplasmin also increases LDL oxidation by vascular cells. In metal ion-free medium, human ceruloplasmin increased bovine aortic SMC- and EC-mediated LDL oxidation by up to 30- and 15-fold, respectively. The maximal response was at 100-300 microg ceruloplasmin/ml, a level at or below the unevoked physiological plasma concentration. Oxidant activity was dependent on protein structure as a specific proteolytic cleavage or removal of one of the seven ceruloplasmin copper atoms inhibited activity. Three lines of evidence indicated a critical role for cellular superoxide (O2.) in ceruloplasmin-stimulated oxidation. First, the rate of production of O2. by cells correlated with their rates of LDL oxidation. Second, superoxide dismutase effectively blocked ceruloplasmin-stimulated oxidation by both cell types. Finally, O2. production by SMC quantitatively accounted for the observed rate of LDL oxidation. To show this, the course of O2. production by SMC was simulated by repeated addition of xanthine and xanthine oxidase to culture medium under cell-free conditions. Neither ceruloplasmin nor O2. alone increased LDL oxidation, but together they completely reconstituted the oxidation rate of ceruloplasmin-stimulated SMC. These results are the first to show that ceruloplasmin stimulates EC- and SMC-mediated oxidation of LDL and that cell-derived O2. accounts quantitatively for metal-dependent, free radical-initiated oxidation of LDL by these cells.

  4. 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. PMID:24554022

  5. Increased density of tolerogenic dendritic cells in the small bowel mucosa of celiac patients

    PubMed Central

    Vorobjova, Tamara; Uibo, Oivi; Heilman, Kaire; Uibo, Raivo

    2015-01-01

    AIM: To investigate the densities of dendritic cells (DCs) and FOXP3+ regulatory T cells (Tregs) and their interrelations in the small bowel mucosa in untreated celiac disease (CD) patients with and without type 1 diabetes (T1D). METHODS: Seventy-four patients (45 female, 29 male, mean age 11.1 ± 6.8 years) who underwent small bowel biopsy were studied. CD without T1D was diagnosed in 18 patients, and CD with T1D was diagnosed in 15 patients. Normal small bowel mucosa was found in two T1D patients. Thirty-nine patients (mean age 12.8 ± 4.9 years) with other diagnoses (functional dyspepsia, duodenal ulcer, erosive gastritis, etc.) formed the control group. All CD patients had partial or subtotal villous atrophy according to the Marsh classification: Marsh grade IIIa in 9, grade IIIb in 21 and grade IIIc in 3 cases. Thirty-nine patients without CD and 2 with T1D had normal small bowel mucosa (Marsh grade 0). The densities of CD11c+, IDO+, CD103+, Langerin (CD207+) DCs and FOXP3+ Tregs were investigated by immunohistochemistry (on paraffin-embedded specimens) and immunofluorescence (on cryostat sections) methods using a combination of mono- and double-staining. Sixty-six serum samples were tested for IgA-tissue transglutaminase (tTG) using a fully automated EliA™ Celikey® IgA assay (Pharmacia Diagnostics, Freiburg, Germany). RESULTS: The density of CD11c+ DCs was significantly increased in CD patients compared with patients with normal mucosa (21.67 ± 2.49 vs 13.58 ± 1.51, P = 0.007). The numbers of FOXP3+ cells were significantly higher in CD patients (10.66 ± 1.50 vs 1.92 ± 0.37, P = 0.0002) and in patients with CD and coexisting T1D (8.11 ± 1.64 vs 1.92 ± 0.37, P = 0.002) compared with patients with normal mucosa. The density of FOXP3+ cells significantly correlated with the histological grade of atrophic changes in the small bowel mucosa according to the March classification (r = 0.62; P < 0.0001) and with levels of IgA antibody (r = 0.55; P < 0

  6. 40 CFR 797.1050 - Algal acute toxicity test.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and sterilization. New test containers may contain substances which inhibit growth of algae. They.... (A) Formulation and sterilization of nutrient medium used for algal culture and preparation of...

  7. High Density Crossbar Arrays with Sub- 15 nm Single Cells via Liftoff Process Only

    PubMed Central

    Khiat, Ali; Ayliffe, Peter; Prodromakis, Themistoklis

    2016-01-01

    Emerging nano-scale technologies are pushing the fabrication boundaries at their limits, for leveraging an even higher density of nano-devices towards reaching 4F2/cell footprint in 3D arrays. Here, we study the liftoff process limits to achieve extreme dense nanowires while ensuring preservation of thin film quality. The proposed method is optimized for attaining a multiple layer fabrication to reliably achieve 3D nano-device stacks of 32 × 32 nanowire arrays across 6-inch wafer, using electron beam lithography at 100 kV and polymethyl methacrylate (PMMA) resist at different thicknesses. The resist thickness and its geometric profile after development were identified to be the major limiting factors, and suggestions for addressing these issues are provided. Multiple layers were successfully achieved to fabricate arrays of 1 Ki cells that have sub- 15 nm nanowires distant by 28 nm across 6-inch wafer. PMID:27585643

  8. High Density Crossbar Arrays with Sub- 15 nm Single Cells via Liftoff Process Only.

    PubMed

    Khiat, Ali; Ayliffe, Peter; Prodromakis, Themistoklis

    2016-01-01

    Emerging nano-scale technologies are pushing the fabrication boundaries at their limits, for leveraging an even higher density of nano-devices towards reaching 4F(2)/cell footprint in 3D arrays. Here, we study the liftoff process limits to achieve extreme dense nanowires while ensuring preservation of thin film quality. The proposed method is optimized for attaining a multiple layer fabrication to reliably achieve 3D nano-device stacks of 32 × 32 nanowire arrays across 6-inch wafer, using electron beam lithography at 100 kV and polymethyl methacrylate (PMMA) resist at different thicknesses. The resist thickness and its geometric profile after development were identified to be the major limiting factors, and suggestions for addressing these issues are provided. Multiple layers were successfully achieved to fabricate arrays of 1 Ki cells that have sub- 15 nm nanowires distant by 28 nm across 6-inch wafer. PMID:27585643

  9. Development of silver-zinc cells of improved cycle life and energy density. Final report

    SciTech Connect

    Serenyi, R.

    1996-04-01

    This document describes a Small Business Innovative Research (SBIR) Phase II program. The research was designed to improve the cycle life and energy density of silver zinc cells, particularly those used in naval propulsion systems, by advancing the state of the art of the negative electrode and the separator, which are responsible for most of the shortcomings of this electrochemical couple. Yardney relied on a new class of materials, known as Electro-Permeable Membranes, which were used as additives and/or coatings for the negative electrodes and also as coatings for conventional separator materials, such as cellophane and Celgard (microporous polypropylene). In addition, the use of bismuth oxide in conjunction with other additives to the negative electrode was shown to have a beneficial effect on cycle life and to reduce the hydrogen gassing of charged cells by up to 70%.

  10. Analysis of neuronal cells of dissociated primary culture on high-density CMOS electrode array.

    PubMed

    Matsuda, Eiko; Mita, Takeshi; Hubert, Julien; Bakkum, Douglas; Frey, Urs; Hierlemann, Andreas; Takahashi, Hirokazu; Ikegami, Takashi

    2013-01-01

    Spontaneous development of neuronal cells was recorded around 4-34 days in vitro (DIV) with high-density CMOS array, which enables detailed study of the spatio-temporal activity of neuronal culture. We used the CMOS array to characterize the evolution of the inter-spike interval (ISI) distribution from putative single neurons, and estimate the network structure based on transfer entropy analysis, where each node corresponds to a single neuron. We observed that the ISI distributions gradually obeyed the power law with maturation of the network. The amount of information transferred between neurons increased at the early stage of development, but decreased as the network matured. These results suggest that both ISI and transfer entropy were very useful for characterizing the dynamic development of cultured neural cells over a few weeks. PMID:24109870

  11. Synthetic High-Density Lipoprotein (sHDL) Inhibits Steroid Production in HAC15 Adrenal Cells.

    PubMed

    Taylor, Matthew J; Sanjanwala, Aalok R; Morin, Emily E; Rowland-Fisher, Elizabeth; Anderson, Kyle; Schwendeman, Anna; Rainey, William E

    2016-08-01

    High density lipoprotein (HDL) transported cholesterol represents one of the sources of substrate for adrenal steroid production. Synthetic HDL (sHDL) particles represent a new therapeutic option to reduce atherosclerotic plaque burden by increasing cholesterol efflux from macrophage cells. The effects of the sHDL particles on steroidogenic cells have not been explored. sHDL, specifically ETC-642, was studied in HAC15 adrenocortical cells. Cells were treated with sHDL, forskolin, 22R-hydroxycholesterol, or pregnenolone. Experiments included time and concentration response curves, followed by steroid assay. Quantitative real-time RT-PCR was used to study mRNA of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, lanosterol 14-α-methylase, cholesterol side-chain cleavage enzyme, and steroid acute regulatory protein. Cholesterol assay was performed using cell culture media and cell lipid extracts from a dose response experiment. sHDL significantly inhibited production of cortisol. Inhibition occurred in a concentration- and time-dependent manner and in a concentration range of 3μM-50μM. Forskolin (10μM) stimulated cortisol production was also inhibited. Incubation with 22R-hydroxycholesterol (10μM) and pregnenolone (10μM) increased cortisol production, which was unaffected by sHDL treatment. sHDL increased transcript levels for the rate-limiting cholesterol biosynthetic enzyme, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase. Extracellular cholesterol assayed in culture media showed a positive correlation with increasing concentration of sHDL, whereas intracellular cholesterol decreased after treatment with sHDL. The current study suggests that sHDL inhibits HAC15 adrenal cell steroid production by efflux of cholesterol, leading to an overall decrease in steroid production and an adaptive rise in adrenal cholesterol biosynthesis. PMID:27253994

  12. Expulsion of Symbiotic Algae during Feeding by the Green Hydra – a Mechanism for Regulating Symbiont Density?

    PubMed Central

    Fishman, Yelena; Zlotkin, Eliahu; Sher, Daniel

    2008-01-01

    Background Algal-cnidarian symbiosis is one of the main factors contributing to the success of cnidarians, and is crucial for the maintenance of coral reefs. While loss of the symbionts (such as in coral bleaching) may cause the death of the cnidarian host, over-proliferation of the algae may also harm the host. Thus, there is a need for the host to regulate the population density of its symbionts. In the green hydra, Chlorohydra viridissima, the density of symbiotic algae may be controlled through host modulation of the algal cell cycle. Alternatively, Chlorohydra may actively expel their endosymbionts, although this phenomenon has only been observed under experimentally contrived stress conditions. Principal Findings We show, using light and electron microscopy, that Chlorohydra actively expel endosymbiotic algal cells during predatory feeding on Artemia. This expulsion occurs as part of the apocrine mode of secretion from the endodermal digestive cells, but may also occur via an independent exocytotic mechanism. Significance Our results demonstrate, for the first time, active expulsion of endosymbiotic algae from cnidarians under natural conditions. We suggest this phenomenon may represent a mechanism whereby cnidarians can expel excess symbiotic algae when an alternative form of nutrition is available in the form of prey. PMID:18596972

  13. Diethylstilbestrol increases the density of prolactin cells in male mouse pituitary by inducing proliferation of prolactin cells and transdifferentiation of gonadotropic cells.

    PubMed

    Shukuwa, Keiko; Izumi, Shin-Ichi; Hishikawa, Yoshitaka; Ejima, Kuniaki; Inoue, Satoshi; Muramatsu, Masami; Ouchi, Yasuyoshi; Kitaoka, Takashi; Koji, Takehiko

    2006-07-01

    Diethylstilbestrol (DES) has been implicated in mammalian abnormalities. We examined the effects of DES on follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) cells in the pituitaries of male mice treated with various doses of DES for 20 days. DES reduced the density of FSH and LH cells in a dose-dependent manner, but increased that of PRL cells. When the expression of estrogen receptor (ER) alpha and beta was assessed, an induction of ERbeta by DES was found predominantly in PRL cells. However, since these effects were abolished in ERalpha knockout mice, DES appears to act primarily through ERalpha. When the expression of Ki-67 and Pit-1 in PRL cells was examined at various time-points after DES treatment, some PRL cells became Ki-67 positive at 10-15 days, and Pit-1-positive cells were increased at 5-15 days. Furthermore, some FSH and LH cells became Pit-1 positive, and co-localized with PRL at 5-10 days. Our results indicate that DES increases PRL cells by inducing proliferation of PRL cells and transdifferentiation of FSH/LH cells to PRL cells. PMID:16468032

  14. A high power density miniaturized microbial fuel cell having carbon nanotube anodes

    NASA Astrophysics Data System (ADS)

    Ren, Hao; Pyo, Soonjae; Lee, Jae-Ik; Park, Tae-Jin; Gittleson, Forrest S.; Leung, Frederick C. C.; Kim, Jongbaeg; Taylor, André D.; Lee, Hyung-Sool; Chae, Junseok

    2015-01-01

    Microbial fuel cells (MFCs) are a promising technology capable of directly converting the abundant biomass on the planet into electricity. Prior studies have adopted a variety of nanostructured materials with high surface area to volume ratio (SAV), yet the current and power density of these nanostructured materials do not deliver a significant leap over conventional MFCs. This study presents a novel approach to implement a miniaturized MFC with a high SAV of 4000 m-1 using three different CNT-based electrode materials: Vertically Aligned CNT (VACNT), Randomly Aligned CNT (RACNT), and Spin-Spray Layer-by-Layer (SSLbL) CNT. These CNT-based electrodes show unique biofilm morphology and thickness. The study of performance parameters of miniaturized MFCs with these CNT-electrodes are conducted with respect to a control bare gold electrode. The results show that CNT-based materials attract more exoelectrogens, Geobacter sp., than bare gold, yielding thicker biofilm formation. Among CNT-based electrodes, low sheet resistance electrodes result in thick biofilm generation and high current/power density. The miniaturized MFC having an SSLbL CNT anode exhibits a high volumetric power density of 3320 W m-3. This research may help lay the foundation for future research involving the optimization of MFCS with 2D and 3D nanostructured electrodes.

  15. Glial cell morphological and density changes through the lifespan of rhesus macaques.

    PubMed

    Robillard, Katelyn N; Lee, Kim M; Chiu, Kevin B; MacLean, Andrew G

    2016-07-01

    How aging impacts the central nervous system (CNS) is an area of intense interest. Glial morphology is known to affect neuronal and immune function as well as metabolic and homeostatic balance. Activation of glia, both astrocytes and microglia, occurs at several stages during development and aging. The present study analyzed changes in glial morphology and density through the entire lifespan of rhesus macaques, which are physiologically and anatomically similar to humans. We observed apparent increases in gray matter astrocytic process length and process complexity as rhesus macaques matured from juveniles through adulthood. These changes were not attributed to cell enlargement because they were not accompanied by proportional changes in soma or process volume. There was a decrease in white matter microglial process length as rhesus macaques aged. Aging was shown to have a significant effect on gray matter microglial density, with a significant increase in aged macaques compared with adults. Overall, we observed significant changes in glial morphology as macaques age indicative of astrocytic activation with subsequent increase in microglial density in aged macaques. PMID:26851132

  16. [A Modified Procedure to Isolate Synchronous Cells from Yeasts with Continuous Percoll Density Gradient and Their Raman Discrimination].

    PubMed

    Huang, Shu-shi; Lai, Jun-zhuo; Lu, Ming-qian; Cheng, Qin; Liao, Wei; Chen, Li-mei

    2015-08-01

    A modified procedure of Percoll density gradient centrifugation was developed to isolate and fractionate synchronous cells from stationary phase (sp) cultures of different yeast strains, as well as Raman spectra discrimination of single yeast cells was reported. About 1.75 mL Percoll solution in 2 mL polypropylene centrifugal tube was centrifuged at 19,320 g, 20 °C with an angle rotor for 15 min to form continuous densities gradient (1.00~1.31 g · mL(-1)), approximately 100 μL sample was overlaid onto the preformed continuous density gradient carefully, subsequently, centrifuged at 400 g for 60 min in a tabletop centrifuge equipped with a angle rotor at 25 °C. Yeast samples could be observed that the suspensions were separated into two cell fractions obviously. Both fractions of different yeast strains were respectively determined by differential interference contrast (DIC), phase contrast microscope and synchronous culture to distinguish their morphological and growth trait. The results showed that the lower fraction cells were unbudded, mostly unicellular, highly refractive, homogeneous and uniform in size, and represented growth characteristic synchronously; Their protoplasm had relatively high density, and contained significant concentrations of glycogen; all of which were accordant with description of quiescent yeast cells and G0 cells in previously published paper. It was shown that lower fraction was quiescent cells, synchronous G0 cells as well. A Raman tweezers setup was used to investigate the differences between two fractions, G0 cells and non G0 cells, at a single cell level. The result showed that both G0 cells and the non G0 cells had the same characteristic peaks corresponding biological macromolecules including proteins, carbohydrates and nucleic acids, but all characteristic peak intensities of G0 cells were higher than that of non G0 cells, implied that the macromolecular substance content of G0 cells was more higher. Principal component

  17. Kinetic modeling of rhamnolipid production by Pseudomonas aeruginosa PAO1 including cell density-dependent regulation.

    PubMed

    Henkel, Marius; Schmidberger, Anke; Vogelbacher, Markus; Kühnert, Christian; Beuker, Janina; Bernard, Thomas; Schwartz, Thomas; Syldatk, Christoph; Hausmann, Rudolf

    2014-08-01

    The production of rhamnolipid biosurfactants by Pseudomonas aeruginosa is under complex control of a quorum sensing-dependent regulatory network. Due to a lack of understanding of the kinetics applicable to the process and relevant interrelations of variables, current processes for rhamnolipid production are based on heuristic approaches. To systematically establish a knowledge-based process for rhamnolipid production, a deeper understanding of the time-course and coupling of process variables is required. By combining reaction kinetics, stoichiometry, and experimental data, a process model for rhamnolipid production with P. aeruginosa PAO1 on sunflower oil was developed as a system of coupled ordinary differential equations (ODEs). In addition, cell density-based quorum sensing dynamics were included in the model. The model comprises a total of 36 parameters, 14 of which are yield coefficients and 7 of which are substrate affinity and inhibition constants. Of all 36 parameters, 30 were derived from dedicated experimental results, literature, and databases and 6 of them were used as fitting parameters. The model is able to describe data on biomass growth, substrates, and products obtained from a reference batch process and other validation scenarios. The model presented describes the time-course and interrelation of biomass, relevant substrates, and products on a process level while including a kinetic representation of cell density-dependent regulatory mechanisms. PMID:24770383

  18. Stimulated arachidonate metabolism during foam cell transformation of mouse peritoneal macrophages with oxidized low density lipoprotein.

    PubMed Central

    Yokode, M; Kita, T; Kikawa, Y; Ogorochi, T; Narumiya, S; Kawai, C

    1988-01-01

    Changes in arachidonate metabolism were examined in mouse peritoneal macrophages incubated with various types of lipoproteins. Oxidized low density lipoprotein (LDL) was incorporated by macrophages and stimulated macrophage prostaglandin E2 (PGE2) and leukotriene C4 syntheses, respectively, 10.8- and 10.7-fold higher than by the control. Production of 6-keto-PGF1 alpha, a stable metabolite of prostacyclin, was also stimulated. No stimulation was found with native LDL, which was minimally incorporated by the cells. Acetylated LDL and beta-migrating very low density lipoprotein (beta-VLDL), though incorporated more efficiently than oxidized LDL, also had no stimulatory effect. When oxidized LDL was separated into the lipoprotein-lipid peroxide complex and free lipid peroxides, most of the stimulatory activity was found in the former fraction, indicating that stimulation of arachidonate metabolism in the cell is associated with uptake of the lipoprotein-lipid peroxide complex. These results suggest that peroxidative modification of LDL could contribute to the progression of atheroma by stimulating arachidonate metabolism during incorporation into macrophages. Images PMID:3125226

  19. Argon metastable densities in the GEC reference cell: A numerical study

    SciTech Connect

    Rauf, S.; Kushner, M.J.

    1996-12-31

    The Gaseous Electronics Conference (GEC) reference cell was introduced several years ago as a standard parallel plate capacitively coupled experimental platform for comparing measurements from different research groups and providing reliable data for evaluating models. Recently, McMillin and Zachariah applied planar laser-induced fluorescence to construct two-dimensional profiles of argon metastable densities in argon, Ar, Ar/O{sub 2} and Ar/CF{sub 4} plasmas over a wide range of gas pressures and applied rf voltages. They observed systematic trends in the spatial distributions and magnitudes of the Ar* densities. In this paper, the authors report on a numerical investigation of the GEC reference cell for the conditions of these experiments with the goals of identifying the processes responsible for the experimental observations. The numerical model used in this study is based on a previously described hybrid simulation originally developed for inductively coupled plasmas. In the model, ions and neutrals are simulated using fluid techniques, while a Monte Carlo (MC) simulation is used for computing the electron dynamics. The fluid and MC modules, coupled with a solution of Poisson`s equation, are iterated until quasi-steady state conditions are obtained. Simulations were performed for the experimental parameter space of 100--1,000 mTorr and rf voltage of 75--300 V.

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

    PubMed

    McDole, B; Isgor, C; Pare, C; Guthrie, K

    2015-09-24

    Olfactory bulb granule cells (GCs) 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 GC spines. These contacts are established in the distal apical dendritic compartment, while GC 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 GC 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 GC spine maturation or maintenance. Here we show that, in vivo, sustained bulbar over-expression of BDNF in transgenic mice produces a marked increase in GC 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 GCs, suggesting a role for this factor in modulating GC functional connectivity within adult olfactory circuitry. PMID:26211445

  1. Durability of Low Platinum Fuel Cells Operating at High Power Density

    SciTech Connect

    Polevaya, Olga; Blanchet, Scott; Ahluwalia, Rajesh; Borup, Rod; Mukundan, Rangachary

    2014-03-19

    Understanding and improving the durability of cost-competitive fuel cell stacks is imperative to successful deployment of the technology. Stacks will need to operate well beyond today’s state-of-the-art rated power density with very low platinum loading in order to achieve the cost targets set forth by DOE ($15/kW) and ultimately be competitive with incumbent technologies. An accelerated cost-reduction path presented by Nuvera focused on substantially increasing power density to address non-PGM material costs as well as platinum. The study developed a practical understanding of the degradation mechanisms impacting durability of fuel cells with low platinum loading (≤0.2mg/cm2) operating at high power density (≥1.0W/cm2) and worked out approaches for improving the durability of low-loaded, high-power stack designs. Of specific interest is the impact of combining low platinum loading with high power density operation, as this offers the best chance of achieving long-term cost targets. A design-of-experiments approach was utilized to reveal and quantify the sensitivity of durability-critical material properties to high current density at two levels of platinum loading (the more conventional 0.45 mgPt.cm–1 and the much lower 0.2 mgPt.cm–2) across several cell architectures. We studied the relevance of selected component accelerated stress tests (AST) to fuel cell operation in power producing mode. New stress tests (NST) were designed to investigate the sensitivity to the addition of electrical current on the ASTs, along with combined humidity and load cycles and, eventually, relate to the combined city/highway drive cycle. Changes in the cathode electrochemical surface area (ECSA) and average oxygen partial pressure on the catalyst layer with aging under AST and NST protocols were compared based on the number of completed cycles. Studies showed elevated sensitivity of Pt growth to the potential limits and the initial particle size distribution. The ECSA loss

  2. Higher-Density Culture in Human Embryonic Stem Cells Results in DNA Damage and Genome Instability.

    PubMed

    Jacobs, Kurt; Zambelli, Filippo; Mertzanidou, Afroditi; Smolders, Ilse; Geens, Mieke; Nguyen, Ha Thi; Barbé, Lise; Sermon, Karen; Spits, Claudia

    2016-03-01

    Human embryonic stem cells (hESC) show great promise for clinical and research applications, but their well-known proneness to genomic instability hampers the development to their full potential. Here, we demonstrate that medium acidification linked to culture density is the main cause of DNA damage and genomic alterations in hESC grown on feeder layers, and this even in the short time span of a single passage. In line with this, we show that increasing the frequency of the medium refreshments minimizes the levels of DNA damage and genetic instability. Also, we show that cells cultured on laminin-521 do not present this increase in DNA damage when grown at high density, although the (long-term) impact on their genomic stability remains to be elucidated. Our results explain the high levels of genome instability observed over the years by many laboratories worldwide, and show that the development of optimal culture conditions is key to solving this problem. PMID:26923824

  3. Higher-Density Culture in Human Embryonic Stem Cells Results in DNA Damage and Genome Instability

    PubMed Central

    Jacobs, Kurt; Zambelli, Filippo; Mertzanidou, Afroditi; Smolders, Ilse; Geens, Mieke; Nguyen, Ha Thi; Barbé, Lise; Sermon, Karen; Spits, Claudia

    2016-01-01

    Summary Human embryonic stem cells (hESC) show great promise for clinical and research applications, but their well-known proneness to genomic instability hampers the development to their full potential. Here, we demonstrate that medium acidification linked to culture density is the main cause of DNA damage and genomic alterations in hESC grown on feeder layers, and this even in the short time span of a single passage. In line with this, we show that increasing the frequency of the medium refreshments minimizes the levels of DNA damage and genetic instability. Also, we show that cells cultured on laminin-521 do not present this increase in DNA damage when grown at high density, although the (long-term) impact on their genomic stability remains to be elucidated. Our results explain the high levels of genome instability observed over the years by many laboratories worldwide, and show that the development of optimal culture conditions is key to solving this problem. PMID:26923824

  4. The ability of the branchiopod, Artemia salina, to graze upon harmful algal blooms caused by Alexandrium fundyense, Aureococcus anophagefferens, and Cochlodinium polykrikoides

    NASA Astrophysics Data System (ADS)

    Marcoval, M. Alejandra; Pan, Jerónimo; Tang, Yingzhong; Gobler, Christopher J.

    2013-10-01

    We present experiments that examined the grazing and survivorship of zooplankton native (Acartia tonsa) and non-native (Artemia salina) to NY (USA) estuaries when exposed to blooms and cultures of the three harmful algae native to NY, Alexandrium fundyense, Aureococcus anophagefferens (strains CCMP 1850 and CCMP 1984) and Cochlodinium polykrikoides. During experiments with cultures of A. anophagefferens, clearance rates (CR) of A. salina were significantly greater than those of A. tonsa for both algal strains examined. A. salina fed on cultures of C. polykrikoides at higher rates than all phytoplankton species examined, including the control diet (Rhodomonas salina), and faster than rates of A. tonsa fed C. polykrikoides. During experiments with A. fundyense, A. salina actively grazed all cell concentrations (250-1500 cells ml-1) while A. tonsa did not feed at any concentration. Percent mortality of A. salina and A. tonsa fed A. fundyense for 48 h were 43 ± 7.7% and 72 ± 7.8%, respectively, percentages significantly higher than those of individuals fed all other algal diets. During 25 field experiments using natural blooms of the three HAB species performed across six NY estuaries, A. salina significantly (p < 0.05) reduced cell densities of A. anophagefferens, C. polykrikoides, and A. fundyense relative to the control treatments in all but one experiment. The sum of these findings demonstrates that a failure to graze these HABs by the indigenous copepod, A. tonsa, may permit blooms to occur. In addition, the ability of A. salina to graze these HABs at densities that were inhibitory to A. tonsa suggests that A. salina could, in some circumstances, be considered as a part of mitigation strategy for these events.

  5. High-density lipoprotein is a potential growth factor for adrenocortical cells

    SciTech Connect

    Murao, Koji . E-mail: mkoji@kms.ac.jp; Imachi, Hitomi; Cao, Wenming; Yu, Xiao; Li, Junhua; Yoshida, Kazuya; Ahmed, Rania A.M.; Matsumoto, Kensuke; Nishiuchi, Takamasa; Ishida, Toshihiko; Wong, Norman C.W.

    2006-05-26

    The entry of cholesterol contained within high-density lipoprotein (HDL) into adrenocortical cells is mediated by a human homologue of SR-BI, CD36, and LIMPII Analogous-1 (CLA-1) and thus augmenting their growth. To address the role of CLA-1, we created a mutant mCLA that lacked the C-terminal tail. HDL CE selective uptake by cells carrying the mCLA-1 receptor was fully active and equivalent to those transfected with full-length CLA-1 (fCLA-1). Expression of mCLA inhibited the proliferation of an adrenocortical cell line and the incorporation of [{sup 3}H]thymidine into the cells. This effect was sensitive to wortmannin, an inhibitor of phosphoinositide 3-kinase (PI3K). Our transcriptional studies revealed that the inhibitory action of mCLA required the transcriptional factor AP-1 and the effect of HDL on AP-1 activation was also abrogated by wortmannin. These findings raise the possibility that the inhibitors of the effects of HDL may be of therapeutic value for adrenocortical tumor.

  6. Protective effect of oleanolic acid on oxidized-low density lipoprotein induced endothelial cell apoptosis.

    PubMed

    Cao, Jianhua; Li, Guanghui; Wang, Meizhi; Li, Hui; Han, Zhiwu

    2015-10-01

    Oleanolic acid (3β-hydroxyolean-12-en-28-oic acid, OA) is a naturally-occurring triterpenoid with various promising pharmacological properties. The present study was conducted to determine the protective effects of OA against oxidized low-density lipoprotein (ox-LDL) induced endothelial cell apoptosis and the possible underlying mechanisms. Our results showed that ox-LDL significantly decreased cell viability and induced apoptosis in human umbilical vein endothelial cells (HUVECs). OA in the co-treatment showed a protective effect against ox-LDL induced loss in cell viability and an increase in apoptosis, which was associated with the modulating effect of OA on ox-LDL induced hypoxia-inducible factor 1α(HIF-1α) expression. Moreover, our results showed that the modulating effect of OA against ox-LDL induced HIF-1α expression was obtained via inhibition of lipoprotein receptor 1 (LOX-1)/reactive oxygen species (ROS) signaling. Collectively, we suggested that the protective effect of OA against ox-LDL induced HUVEC apoptosis might, at least in part, be obtained via inhibition of the LOX-1/ROS/HIF-1α signaling pathway. PMID:26559024

  7. T-cell activation: A queuing theory analysis at low agonist density.

    PubMed

    Wedagedera, J R; Burroughs, N J

    2006-09-01

    We analyze a simple linear triggering model of the T-cell receptor (TCR) within the framework of queuing theory, in which TCRs enter the queue upon full activation and exit by downregulation. We fit our model to four experimentally characterized threshold activation criteria and analyze their specificity and sensitivity: the initial calcium spike, cytotoxicity, immunological synapse formation, and cytokine secretion. Specificity characteristics improve as the time window for detection increases, saturating for time periods on the timescale of downregulation; thus, the calcium spike (30 s) has low specificity but a sensitivity to single-peptide MHC ligands, while the cytokine threshold (1 h) can distinguish ligands with a 30% variation in the complex lifetime. However, a robustness analysis shows that these properties are degraded when the queue parameters are subject to variation-for example, under stochasticity in the ligand number in the cell-cell interface and population variation in the cellular threshold. A time integration of the queue over a period of hours is shown to be able to control parameter noise efficiently for realistic parameter values when integrated over sufficiently long time periods (hours), the discrimination characteristics being determined by the TCR signal cascade kinetics (a kinetic proofreading scheme). Therefore, through a combination of thresholds and signal integration, a T cell can be responsive to low ligand density and specific to agonist quality. We suggest that multiple threshold mechanisms are employed to establish the conditions for efficient signal integration, i.e., coordinate the formation of a stable contact interface. PMID:16766611

  8. Enhanced photocurrent density in graphene/Si based solar cell (GSSC) by optimizing active layer thickness

    SciTech Connect

    Rosikhin, Ahmad Hidayat, Aulia Fikri; Syuhada, Ibnu; Winata, Toto

    2015-12-29

    Thickness dependent photocurrent density in active layer of graphene/Si based solar cell has been investigated via analytical – simulation study. This report is a preliminary comparison of experimental and analytical investigation of graphene/Si based solar cell. Graphene sheet was interfaced with Si thin film forming heterojunction solar cell that was treated as a device model for photocurrent generator. Such current can be enhanced by optimizing active layer thickness and involving metal oxide as supporting layer to shift photons absorption. In this case there are two type of devices model with and without TiO{sub 2} in which the silicon thickness varied at 20 – 100 nm. All of them have examined and also compared with each other to obtain an optimum value. From this calculation it found that generated currents almost linear with thickness but there are saturated conditions that no more enhancements will be achieved. Furthermore TiO{sub 2} layer is effectively increases photon absorption but reducing device stability, maximum current is fluctuates enough. This may caused by the disturbance of excitons diffusion and resistivity inside each layer. Finally by controlling active layer thickness, it is quite useful to estimate optimization in order to develop the next solar cell devices.

  9. T-Cell Activation: A Queuing Theory Analysis at Low Agonist Density

    PubMed Central

    Wedagedera, J. R.; Burroughs, N. J.

    2006-01-01

    We analyze a simple linear triggering model of the T-cell receptor (TCR) within the framework of queuing theory, in which TCRs enter the queue upon full activation and exit by downregulation. We fit our model to four experimentally characterized threshold activation criteria and analyze their specificity and sensitivity: the initial calcium spike, cytotoxicity, immunological synapse formation, and cytokine secretion. Specificity characteristics improve as the time window for detection increases, saturating for time periods on the timescale of downregulation; thus, the calcium spike (30 s) has low specificity but a sensitivity to single-peptide MHC ligands, while the cytokine threshold (1 h) can distinguish ligands with a 30% variation in the complex lifetime. However, a robustness analysis shows that these properties are degraded when the queue parameters are subject to variation—for example, under stochasticity in the ligand number in the cell-cell interface and population variation in the cellular threshold. A time integration of the queue over a period of hours is shown to be able to control parameter noise efficiently for realistic parameter values when integrated over sufficiently long time periods (hours), the discrimination characteristics being determined by the TCR signal cascade kinetics (a kinetic proofreading scheme). Therefore, through a combination of thresholds and signal integration, a T cell can be responsive to low ligand density and specific to agonist quality. We suggest that multiple threshold mechanisms are employed to establish the conditions for efficient signal integration, i.e., coordinate the formation of a stable contact interface. PMID:16766611

  10. Algal Attributes: An Autecological Classification of Algal Taxa Collected by the National Water-Quality Assessment Program

    USGS Publications Warehouse

    Porter, Stephen D.

    2008-01-01

    Algae are excellent indicators of water-quality conditions, notably nutrient and organic enrichment, and also are indicators of major ion, dissolved oxygen, and pH concentrations and stream microhabitat conditions. The autecology, or physiological optima and tolerance, of algal species for various water-quality contaminants and conditions is relatively well understood for certain groups of freshwater algae, notably diatoms. However, applications of autecological information for water-quality assessments have been limited because of challenges associated with compiling autecological literature from disparate sources, tracking name changes for a large number of algal species, and creating an autecological data base from which algal-indicator metrics can be calculated. A comprehensive summary of algal autecological attributes for North American streams and rivers does not exist. This report describes a large, digital data file containing 28,182 records for 5,939 algal taxa, generally species or variety, collected by the U.S. Geological Survey?s National Water-Quality Assessment (NAWQA) Program. The data file includes 37 algal attributes classified by over 100 algal-indicator codes or metrics that can be calculated easily with readily available software. Algal attributes include qualitative classifications based on European and North American autecological literature, and semi-quantitative, weighted-average regression approaches for estimating optima using regional and national NAWQA data. Applications of algal metrics in water-quality assessments are discussed and national quartile distributions of metric scores are shown for selected indicator metrics.

  11. Addressing the challenges for sustainable production of algal biofuels: I. Algal strains and nutrient supply.

    PubMed

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

    2013-01-01

    Microalgae hold promise for the production of sustainable replacement of fossil fuels due to their high growth rates, ability to grow on non-arable land and their high content, under the proper conditions, of high energy compounds that can be relatively easily chemically converted to fuels using existing technology. However, projected large-scale algal production raises a number of sustainability concerns concerning land use, net energy return, water use and nutrient supply. The state-of-the-art of algal production of biofuels is presented with emphasis on some possible avenues to provide answers to the sustainability questions that have been raised. Here, issues concerning algal strains and supply of nutrients for large-scale production are discussed. Since sustainability concerns necessitate the use of wastewaters for supply of bulk nutrients, emphasis is placed on the composition and suitability of different wastewater streams. At the same time, algal cultivation has proven useful in waste treatment processes, and thus this aspect is also treated in some detail. PMID:24350435

  12. Enhanced current and power density of micro-scale microbial fuel cells with ultramicroelectrode anodes

    NASA Astrophysics Data System (ADS)

    Ren, Hao; Rangaswami, Sriram; Lee, Hyung-Sool; Chae, Junseok

    2016-09-01

    We present a micro-scale microbial fuel cell (MFC) with an ultramicroelectrode (UME) anode, with the aim of creating a miniaturized high-current/power-density converter using carbon-neutral and renewable energy sources. Micro-scale MFCs have been studied for more than a decade, yet their current and power densities are still an order of magnitude lower than those of their macro-scale counterparts. In order to enhance the current/power densities, we engineer a concentric ring-shaped UME, with a width of 20 μm, to facilitate the diffusion of ions in the vicinity of the micro-organisms that form biofilm on the UME. The biofilm extends approximately 15 μm from the edge of the UME, suggesting the effective biofilm area increases. Measured current/power densities per the effective area and the original anode area are 7.08  ±  0.01 A m‑2 & 3.09  ±  0.04 W m‑2 and 17.7  ±  0.03 A m‑2 & 7.72  ±  0.09 W m‑2, respectively. This is substantially higher than any prior work in micro-scale MFCs, and very close, or even higher, to that of macro-scale MFCs. A Coulombic efficiency, a measure of how efficiently an MFC harvests electrons from donor substrate, of 70%, and an energy conversion efficiency of 17% are marked, highlighting the micro-scale MFC as an attractive alternative within the existing energy conversion portfolio.

  13. T Lymphocyte Density and Distribution in Human Colorectal Mucosa, and Inefficiency of Current Cell Isolation Protocols

    PubMed Central

    Preza, Gloria Cuevas; Yang, Otto O.; Elliott, Julie; Anton, Peter A.; Ochoa, Maria T.

    2015-01-01

    Mucosal tissues are critical immune effector sites containing complex populations of leukocytes in a tissue microenvironment that remains incompletely understood. We identify and quantify in human distal colorectal tissue absolute mucosal CD3+ lymphocytes, including CD4+ and CD8+ subsets, by direct visualization using immunohistochemistry (IHC), immunofluorescence (IF), and an automated counting protocol (r2=0.90). Sigmoid and rectal mucosal tissues are both densely packed with T lymphocytes in the mucosal compartment. Both compartments had similar densities of CD3+ T lymphocytes with 37,400 ± 2,801 cells/mm3 and 33,700 ± 4,324 cell/mm3, respectively. Sigmoid mucosa contained 57% CD3+CD4+ and 40% CD3+CD8+ T lymphocytes which calculates to 21,300 ± 1,476/mm3 and 15,000 ± 275/mm3 T lymphocytes, respectively. Rectal mucosa had 57% CD3+CD4+ and 42% CD3+CD8+ or 21,577 ± 332, and 17,090 ± 1,206 cells/mm3, respectively. By comparison, sigmoid mucosal biopsies subjected to conventional collagenase digestion, mononuclear cell (MMC) isolation and staining for flow cytometry yielded 4,549 ± 381/mm3 and 2,708 ± 245/mm3 CD4+ and CD8+ T lymphocytes. These data suggest only ~20.7% recovery compared to IHC results for these markers. Further studies will determine if this reflects a selective bias in only CD3+, CD4+ and CD8+ T cells or can be generalized to all flow-analyzed cells from mucosal tissues for phenotyping and functional testing. PMID:25856343

  14. Control of density-dependent, cell state-specific signal transduction by the cell adhesion molecule CEACAM1, and its influence on cell cycle regulation

    SciTech Connect

    Scheffrahn, Inka; Singer, Bernhard B.; Sigmundsson, Kristmundur; Lucka, Lothar; Oebrink, Bjoern . E-mail: bjorn.obrink@cmb.ki.se

    2005-07-15

    Growth factor receptors, extracellular matrix receptors, and cell-cell adhesion molecules co-operate in regulating the activities of intracellular signaling pathways. Here, we demonstrate that the cell adhesion molecule CEACAM1 co-regulates growth-factor-induced DNA synthesis in NBT-II epithelial cells in a cell-density-dependent manner. CEACAM1 exerted its effects by regulating the activity of the Erk 1/2 MAP kinase pathway and the expression levels of the cyclin-dependent kinase inhibitor p27{sup Kip1}. Interestingly, both inhibitory and stimulatory effects were observed. Confluent cells continuously exposed to fetal calf serum showed little Erk activity and DNA synthesis compared with sparse cells. Under these conditions, anti-CEACAM1 antibodies strongly stimulated Erk activation, decreased p27 expression, and induced DNA synthesis. In serum-starved confluent cells, re-addition of 10% fetal calf serum activated the Erk pathway, decreased p27 expression, and stimulated DNA synthesis to the same levels as in sparse cells. Under these conditions anti-CEACAM1 antibodies de-activated Erk, restored the level of p27, and inhibited DNA synthesis. These data indicate that CEACAM1 mediates contact inhibition of proliferation in cells that are constantly exposed to growth factors, but co-activates growth-factor-induced proliferation in cells that have been starved for growth factors; exposure to extracellular CEACAM1 ligands reverts these responses.

  15. High-Energy-Density, Low-Temperature Li/CFx Primary Cells

    NASA Technical Reports Server (NTRS)

    Whitacre, Jay; Bugga, Ratnakumar; Smart, Marshall; Prakash, G.; Yazami, Rachid

    2007-01-01

    High-energy-density primary (nonrechargeable) electrochemical cells capable of relatively high discharge currents at temperatures as low as -40 C have been developed through modification of the chemistry of commercial Li/CFx cells and batteries. The commercial Li/CFx units are not suitable for high-current and low-temperature applications because they are current limited and their maximum discharge rates decrease with decreasing temperature. The term "Li/CFx" refers to an anode made of lithium and a cathode made of a fluorinated carbonaceous material (typically graphite). In commercial cells, x typically ranges from 1.05 to 1.1. This cell composition makes it possible to attain specific energies up to 800 Wh/kg, but in order to prevent cell polarization and the consequent large loss of cell capacity, it is typically necessary to keep discharge currents below C/50 (where C is numerically equal to the current that, flowing during a charge or discharge time of one hour, would integrate to the nominal charge or discharge capacity of a cell). This limitation has been attributed to the low electronic conductivity of CFx for x approx. 1. To some extent, the limitation might be overcome by making cathodes thinner, and some battery manufacturers have obtained promising results using thin cathode structures in spiral configurations. The present approach includes not only making cathodes relatively thin [.2 mils (.0.051 mm)] but also using sub-fluorinated CFx cathode materials (x < 1) in conjunction with electrolytes formulated for use at low temperatures. The reason for choosing sub-fluorinated CFx cathode materials is that their electronic conductivities are high, relative to those for which x > 1. It was known from recent prior research that cells containing sub-fluorinated CFx cathodes (x between 0.33 and 0.66) are capable of retaining substantial portions of their nominal low-current specific energies when discharged at rates as high as 5C at room temperature. However

  16. Estimation of algal and suspended sediment loads (singly and combined) using hyperspectral sensors and integrated mesocosm experiments

    SciTech Connect

    Schalles, J.F.; Schiebe, F.R.; Starks, P.J.

    1997-06-01

    Most remote sensing algorithms for materials in water are based on studies on natural waters with complex and variable optical properties, or of small indoor microcosm containers. We used sunlit, cylindrical, black mesocosm tanks (80m{sup 3}, 3 m depth) and a hyperspectral radiometer to examine reflectances of algal blooms and suspended kaolin white clay. In three integrated experiments, algae and clay levels were carefully manipulated: (1) Algal bloom water in one tank was pumped to a second which began with clear water, and clear make-up water was pumped to the first to obtain a well graded series (Chl. a = 0 - 62 {mu}g/L). (2) White, kaolin clay was added stepwise to clear water, resulting in an organic seston range of 0 - 40 mg/L. (3) Algal bloom water from a single source was divided between two tanks to establish Chi. a loads of 31 and 57 {mu}g/L. Then, identical additions of clay were made to both tanks to achieve a range of 0 - 72 mg/L inorganic matter while conserving the algal loads. The first experiment revealed a strong interplay between algal scattering and absorption. Pigment absorbance dominated below 510 nm, while increasing cell scattering in regions of low pigment activity caused green and NIR peaks to form near 560 and 700 nm. In spite of strong chlorophyll absorbance near 675 nm, this region had small reflectance increases with increased algae. In the second experiment, white clay had high albedo. At seston levels above 40 mg/L, green reflectance exceeded 50% and NIR reflectance at 800 nm exceeded 9%. In the third experiment, algal pigments strongly attenuated clay reflectance in a dose dependent manner, even at green wavelengths. Clay particles greatly amplified but also preserved algal reflectance patterns. Our findings affirm the importance of high spectral resolution at diagnostic wavelengths in turbid Case 2 coastal and inland waters.

  17. Cell infiltration and growth in a low density, uncompressed three-dimensional electrospun nanofibrous scaffold.

    PubMed

    Blakeney, Bryan A; Tambralli, Ajay; Anderson, Joel M; Andukuri, Adinarayana; Lim, Dong-Jin; Dean, Derrick R; Jun, Ho-Wook

    2011-02-01

    A limiting factor of traditional electrospinning is that the electrospun scaffolds consist entirely of tightly packed nanofiber layers that only provide a superficial porous structure due to the sheet-like assembly process. This unavoidable characteristic hinders cell infiltration and growth throughout the nanofibrous scaffolds. Numerous strategies have been tried to overcome this challenge, including the incorporation of nanoparticles, using larger microfibers, or removing embedded salt or water-soluble fibers to increase porosity. However, these methods still produce sheet-like nanofibrous scaffolds, failing to create a porous three-dimensional scaffold with good structural integrity. Thus, we have developed a three-dimensional cotton ball-like electrospun scaffold that consists of an accumulation of nanofibers in a low density and uncompressed manner. Instead of a traditional flat-plate collector, a grounded spherical dish and an array of needle-like probes were used to create a Focused, Low density, Uncompressed nanoFiber (FLUF) mesh scaffold. Scanning electron microscopy showed that the cotton ball-like scaffold consisted of electrospun nanofibers with a similar diameter but larger pores and less-dense structure compared to the traditional electrospun scaffolds. In addition, laser confocal microscopy demonstrated an open porosity and loosely packed structure throughout the depth of the cotton ball-like scaffold, contrasting the superficially porous and tightly packed structure of the traditional electrospun scaffold. Cells seeded on the cotton ball-like scaffold infiltrated into the scaffold after 7 days of growth, compared to no penetrating growth for the traditional electrospun scaffold. Quantitative analysis showed approximately a 40% higher growth rate for cells on the cotton ball-like scaffold over a 7 day period, possibly due to the increased space for in-growth within the three-dimensional scaffolds. Overall, this method assembles a nanofibrous scaffold

  18. LOW-TEMPERATURE, ANODE-SUPPORTED HIGH POWER DENSITY SOLID OXIDE FUEL CELLS WITH NANOSTRUCTURED ELECTRODES

    SciTech Connect

    Anil V. Virkar

    2001-09-26

    Anode-supported solid oxide fuel cells with Ni + yttria-stabilized zirconia (YSZ) anode, YSZ-samaria-doped ceria (SDC) bi-layer electrolyte and Sr-doped LaCoO{sub 3} (LSC) + SDC cathode were fabricated. Fuel used consisted of H{sub 2} diluted with He, N{sub 2}, H{sub 2}O or CO{sub 2}, mixtures of H{sub 2} and CO, and mixtures of CO and CO{sub 2}. Cell performance was measured at 800 C with above-mentioned fuel gas mixtures and air as oxidant. For a given concentration of the diluent, the cell performance was higher with He as the diluent than with N{sub 2} as the diluent. Mass transport through porous Ni-YSZ anode for H{sub 2}-H{sub 2}O, CO-CO{sub 2} binary systems and H{sub 2}-H{sub 2}O-diluent gas ternary systems was analyzed using multicomponent gas diffusion theory. At high concentrations of the diluent, the maximum achievable current density was limited by the anodic concentration polarization. From this measured limiting current density, the corresponding effective gas diffusivity was estimated. Highest effective diffusivity was estimated for fuel gas mixtures containing H{sub 2}-H{sub 2}O-He mixtures ({approx}0.34 cm{sup 2}/s), and the lowest for CO-CO{sub 2} mixtures ({approx}0.07 cm{sup 2}/s). The lowest performance was observed with CO-CO{sub 2} mixture as a fuel, which in part was attributed to the lowest effective diffusivity of the fuels tested.

  19. Phylogenetic Analysis of Algal Symbionts Associated with Four North American Amphibian Egg Masses

    PubMed Central

    Kim, Eunsoo; Lin, Yuan; Kerney, Ryan; Blumenberg, Lili; Bishop, Cory

    2014-01-01

    Egg masses of the yellow-spotted salamander Ambystoma maculatum form an association with the green alga “Oophila amblystomatis” (Lambert ex Wille), which, in addition to growing within individual egg capsules, has recently been reported to invade embryonic tissues and cells. The binomial O. amblystomatis refers to the algae that occur in A. maculatum egg capsules, but it is unknown whether this population of symbionts constitutes one or several different algal taxa. Moreover, it is unknown whether egg masses across the geographic range of A. maculatum, or other amphibians, associate with one or multiple algal taxa. To address these questions, we conducted a phylogeographic study of algae sampled from egg capsules of A. maculatum, its allopatric congener A. gracile, and two frogs: Lithobates sylvatica and L. aurora. All of these North American amphibians form associations with algae in their egg capsules. We sampled algae from egg capsules of these four amphibians from localities across North America, established representative algal cultures, and amplified and sequenced a region of 18S rDNA for phylogenetic analysis. Our combined analysis shows that symbiotic algae found in egg masses of four North American amphibians are closely related to each other, and form a well-supported clade that also contains three strains of free-living chlamydomonads. We designate this group as the ‘Oophila’ clade, within which the symbiotic algae are further divided into four distinct subclades. Phylogenies of the host amphibians and their algal symbionts are only partially congruent, suggesting that host-switching and co-speciation both play roles in their associations. We also established conditions for isolating and rearing algal symbionts from amphibian egg capsules, which should facilitate further study of these egg mass specialist algae. PMID:25393119

  20. Phylogenetic analysis of algal symbionts associated with four North American amphibian egg masses.

    PubMed

    Kim, Eunsoo; Lin, Yuan; Kerney, Ryan; Blumenberg, Lili; Bishop, Cory

    2014-01-01

    Egg masses of the yellow-spotted salamander Ambystoma maculatum form an association with the green alga "Oophila amblystomatis" (Lambert ex Wille), which, in addition to growing within individual egg capsules, has recently been reported to invade embryonic tissues and cells. The binomial O. amblystomatis refers to the algae that occur in A. maculatum egg capsules, but it is unknown whether this population of symbionts constitutes one or several different algal taxa. Moreover, it is unknown whether egg masses across the geographic range of A. maculatum, or other amphibians, associate with one or multiple algal taxa. To address these questions, we conducted a phylogeographic study of algae sampled from egg capsules of A. maculatum, its allopatric congener A. gracile, and two frogs: Lithobates sylvatica and L. aurora. All of these North American amphibians form associations with algae in their egg capsules. We sampled algae from egg capsules of these four amphibians from localities across North America, established representative algal cultures, and amplified and sequenced a region of 18S rDNA for phylogenetic analysis. Our combined analysis shows that symbiotic algae found in egg masses of four North American amphibians are closely related to each other, and form a well-supported clade that also contains three strains of free-living chlamydomonads. We designate this group as the 'Oophila' clade, within which the symbiotic algae are further divided into four distinct subclades. Phylogenies of the host amphibians and their algal symbionts are only partially congruent, suggesting that host-switching and co-speciation both play roles in their associations. We also established conditions for isolating and rearing algal symbionts from amphibian egg capsules, which should facilitate further study of these egg mass specialist algae. PMID:25393119

  1. Pseudomonas aeruginosa Cytotoxicity Is Attenuated at High Cell Density and Associated with the Accumulation of Phenylacetic Acid

    PubMed Central

    Wang, Jianhe; Dong, Yihu; Zhou, Tielin; Liu, Xiaoling; Deng, Yinyue; Wang, Chao; Lee, Jasmine; Zhang, Lian-Hui

    2013-01-01

    Background P. aeruginosa is known to cause acute cytotoxicity against various human and animal cells and tissues. Methodology/Findings Intriguingly, however, in this study we noticed that while a low cell density inoculum of P. aeruginosa caused severe cytotoxicity against human lung tissue cell line A549, increasing the cell density of bacterial inoculum led to decreased cytotoxicity. Addition of the supernatants from high density bacterial culture to low cell density inoculum protected the human cells from bacterial cytotoxic damage, suggesting that P. aeruginosa may produce and accumulate an inhibitory molecule(s) counteracting its pathogenic infection. The inhibitor was purified from the stationary-phase culture supernatants of P. aeruginosa strain PAO1 using bioassay-guided high performance liquid chromatography (HPLC), and characterized to be phenylacetic acid (PAA) by mass spectrometry and nuclear magnetic resonance spectroscopy. Microarray analysis revealed that treatment of P. aeruginosa with PAA down-regulated the transcriptional expression of Type III secretion system (T3SS) genes and related regulatory genes including rsmA and vfr, which were confirmed by transcriptional and translational analysis. Conclusions Identification of bacterial metabolite PAA as a T3SS-specific inhibitor explains this intriguing inverse cell-density-dependent-cytotoxicity phenomenon as T3SS is known to be a key virulence factor associated with cytotoxicity and acute infection. The findings may provide useful clues for design and development of new strategies to combat this formidable bacterial pathogen. PMID:23555919

  2. Disk Diffusion Assay to Assess the Antimicrobial Activity of Marine Algal Extracts.

    PubMed

    Desbois, Andrew P; Smith, Valerie J

    2015-01-01

    Marine algae are a relatively untapped source of bioactive natural products, including those with antimicrobial activities. The ability to assess the antimicrobial activity of cell extracts derived from algal cultures is vital to identifying species that may produce useful novel antibiotics. One assay that is used widely for this purpose is the disk diffusion assay due to its simplicity, rapidity, and low cost. Moreover, this assay gives output data that are easy to interpret and can be used to screen many samples at once irrespective of the solvent used during preparation. In this chapter, a step-by-step protocol for performing a disk diffusion assay is described. The assay is particularly well suited to testing algal cell extracts and fractions resulting from separation through bioassay-guided approaches. PMID:26108520

  3. A more appropriate white blood cell count for estimating malaria parasite density in Plasmodium vivax patients in northeastern Myanmar.

    PubMed

    Liu, Huaie; Feng, Guohua; Zeng, Weilin; Li, Xiaomei; Bai, Yao; Deng, Shuang; Ruan, Yonghua; Morris, James; Li, Siman; Yang, Zhaoqing; Cui, Liwang

    2016-04-01

    The conventional method of estimating parasite densities employ an assumption of 8000 white blood cells (WBCs)/μl. However, due to leucopenia in malaria patients, this number appears to overestimate parasite densities. In this study, we assessed the accuracy of parasite density estimated using this assumed WBC count in eastern Myanmar, where Plasmodium vivax has become increasingly prevalent. From 256 patients with uncomplicated P. vivax malaria, we estimated parasite density and counted WBCs by using an automated blood cell counter. It was found that WBC counts were not significantly different between patients of different gender, axillary temperature, and body mass index levels, whereas they were significantly different between age groups of patients and the time points of measurement. The median parasite densities calculated with the actual WBC counts (1903/μl) and the assumed WBC count of 8000/μl (2570/μl) were significantly different. We demonstrated that using the assumed WBC count of 8000 cells/μl to estimate parasite densities of P. vivax malaria patients in this area would lead to an overestimation. For P. vivax patients aged five years and older, an assumed WBC count of 5500/μl best estimated parasite densities. This study provides more realistic assumed WBC counts for estimating parasite densities in P. vivax patients from low-endemicity areas of Southeast Asia. PMID:26802490

  4. Composite Cathode for High-Power Density Solid Oxide Fuel Cells

    SciTech Connect

    Ilwon Kim; Scott Barnett; Yi Jiang; Manoj Pillai; Nikkia McDonald; Dan Gostovic; Zhongryang Zhan; Jiang Liu

    2004-01-31

    Reduction of solid oxide fuel cell (SOFC) operating temperature will play a key role in reducing the stack cost by allowing the use of low-cost metallic interconnects and new approaches to sealing, while making applications such as transportation more feasible. Reported results for anode-supported SOFCs show that cathode polarization resistance is the primary barrier to achieving high power densities at operating temperatures of 700 C and lower. This project aims to identify and develop composite cathodes that could reduce SOFC operating temperatures below 700 C. This effort focuses on study and use of (La,Sr)(Co,Fe)O{sub 3} (LSCF) based composite cathodes, which have arguably the best potential to substantially improve on the currently-used, (La,Sr)MnO{sub 3}-Yttria-stabilized Zirconia. During this Phase I, it was successfully demonstrated that high performances can be achieved with LSCF/Gadolinium-Doped Ceria composite cathodes on Ni-based anode supported cells operating at 700 C or lower. We studied electrochemical reactions at LSCF/Yttria-stabilized Zirconia (YSZ) interfaces, and observed chemical reactions between LSCF and YSZ. By using ceria electrolytes or YSZ electrolytes with ceria diffusion barrier layers, the chemical reactions between LSCF and electrolytes were prevented under cathode firing conditions necessary for the optimal adhesion of the cathodes. The protection provided by ceria layer is expected to be adequate for stable long-term cathode performances, but more testing is needed to verify this. Using ceria-based barrier layers, high performance Ni-YSZ anode supported cells have been demonstrated with maximum power densities of 0.8W/cm2 at 700 C and 1.6W/cm{sup 2} at 800 C. Ni-SDC anode supported cells with SDC electrolytes yielded >1W/cm{sup 2} at 600 C. We speculate that the power output of Ni-YSZ anode supported cell at 700 C and lower, was limited by the quality of the Ceria and Ceria YSZ interface. Improvements in the low

  5. Distribution of heavy metals from flue gas in algal bioreactor

    NASA Astrophysics Data System (ADS)

    Napan, Katerine

    Flue gas from coal-fired power plants is a major source of CO2 to the atmosphere. Microalgae can use this enriched form of CO2 as carbon source and in turn the biomass can be used to produce food, feed, fertilizer and biofuels. However, along with CO2, coal-based flue gas will inevitably introduce heavy metals, which have a high affinity to bind algal cells, could be toxic to the organisms and if transferred to the products could limit their uses. This study seeks to address the distribution and impact of heavy metals present in flue gas on microalgae production systems. To comprehend its effects, algae Scenedesmus obliquus was grown in batch reactors in a multimetal system. Ten heavy metals (Cu, Co, Zn, Pb, As, Se, Cr, Hg, Ni and Cd) were selected and were evaluated at four concentrations (1X, 2X, 5X and 10X). Results show that most heavy metals accumulated mainly in biomass and were found in very low concentrations in media. Hg was shown to be lost from the culture, with low amounts present in the biomass. An upper limit for As uptake was observed, suggesting its likelihood to build-up in the system during medium recycle. The As limited bioaccumulation was overcome by addition of sulfur to the algal medium. Heavy metal at 2X, 5X and 10X inhibited both growth and lipid production, while at the reference concentration both biomass and lipids yields were increased. Heavy metal concentrations in the medium and biomass were time dependent, and at the end of the cultivation most heavy metals in the supernatant solution complied with the recommendations for irrigation water, while biomass was below limits for cattle and poultry feed, fertilizer, plastic and paper. This research shows that bioremediation of CO2 and heavy metals in combination with energy production can be integrated, which is an environmentally friendly form of biotechnology.

  6. 40 CFR 797.1050 - Algal acute toxicity test.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 32 2014-07-01 2014-07-01 false Algal acute toxicity test. 797.1050 Section 797.1050 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT (CONTINUED) ENVIRONMENTAL EFFECTS TESTING GUIDELINES Aquatic Guidelines § 797.1050 Algal acute toxicity test. (a) Purpose. The...

  7. What is causing the harmful algal blooms in Lake Erie?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Harmful and nuisance algal blooms have been increasing in size and extent since about 2000. In recent years, the release of the algal toxin microcystin has become a growing concern and has resulted in the inability to use water from Lake Erie as a drinking water source to the 400,000 residents of T...

  8. COMPARISON OF LARGE RIVER SAMPLING METHODS ON ALGAL METRICS

    EPA Science Inventory

    We compared the results of four methods used to assess the algal communities at 60 sites distributed among four rivers. Based on Principle Component Analysis of physical habitat data collected concomitantly with the algal data, sites were separated into those with a mean thalweg...

  9. Algal Lipid Extraction and Upgrading to Hydrocarbons Technology Pathway

    SciTech Connect

    Davis, R.; Biddy, M.; Jones, S.

    2013-03-01

    This technology pathway case investigates the cultivation of algal biomass followed by further lipid extraction and upgrading to hydrocarbon biofuels. Technical barriers and key research needs have been assessed in order for the algal lipid extraction and upgrading pathway to be competitive with petroleum-derived gasoline-, diesel-, and jet-range hydrocarbon blendstocks.

  10. EFFECTS OF MARINE ALGAL TOXINS ON THERMOREGULATION IN MICE.

    EPA Science Inventory

    Hypothermia is often seen in mice and rats exposed acutely to marine algal toxins, but the mechanism of action of these toxins on thermoregulation is not well understood. Our laboratory has assessed the thermoregulatory mechanisms of two marine algal toxins, maitotoxin and brevet...

  11. Near- and mid-infrared spectroscopic determination of algal composition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to investigate the feasibility of using near-infrared reflectance spectroscopy (NIRS) and mid-infrared reflectance spectroscopy (MIRS) to determine the composition of algal samples. We assayed a set of algal biomass samples (n=117), collected from algae turf scrubber...

  12. Cell Density Effects of Frog Skin Bacteria on Their Capacity to Inhibit Growth of the Chytrid Fungus, Batrachochytrium dendrobatidis.

    PubMed

    Yasumiba, Kiyomi; Bell, Sara; Alford, Ross

    2016-01-01

    Bacterial symbionts on frog skin can reduce the growth of the chytrid fungus Batrachochytrium dendrobatidis (Bd) through production of inhibitory metabolites. Bacteria can be effective at increasing the resistance of amphibians to chytridiomycosis when added to amphibian skin, and isolates can be screened for production of metabolites that inhibit Bd growth in vitro. However, some bacteria use density-dependent mechanism such as quorum sensing to regulate metabolite production. It is therefore important to consider cell density effects when evaluating bacteria as possible candidates for bioaugmentation. The aim of our study was to evaluate how the density of cutaneous bacteria affects their inhibition of Bd growth in vitro. We sampled cutaneous bacteria isolated from three frog species in the tropical rainforests of northern Queensland, Australia, and selected ten isolates that were inhibitory to Bd in standardised pilot trials. We grew each isolate in liquid culture at a range of initial dilutions, sub-sampled each dilution at a series of times during the first 48 h of growth and measured spectrophotometric absorbance values, cell counts and Bd-inhibitory activity of cell-free supernatants at each time point. The challenge assay results clearly demonstrated that the inhibitory effects of most isolates were density dependent, with relatively low variation among isolates in the minimum cell density needed to inhibit Bd growth. We suggest the use of minimum cell densities and fast-growing candidate isolates to maximise bioaugmentation efforts. PMID:26563320

  13. Impact of Pancreatic Rat Islet Density on Cell Survival during Hypoxia

    PubMed Central

    Rodriguez-Brotons, A.; Bietiger, W.; Peronet, C.; Magisson, J.; Sookhareea, C.; Langlois, A.; Mura, C.; Jeandidier, N.; Pinget, M.; Sigrist, S.; Maillard, E.

    2016-01-01

    In bioartificial pancreases (BP), the number of islets needed to restore normoglycaemia in the diabetic patient is critical. However, the confinement of a high quantity of islets in a limited space may impact islet survival, particularly in regard to the low oxygen partial pressure (PO2) in such environments. The aim of the present study was to evaluate the impact of islet number in a confined space under hypoxia on cell survival. Rat islets were seeded at three different concentrations (150, 300, and 600 Islet Equivalents (IEQ)/cm2) and cultured in normal atmospheric pressure (160 mmHg) as well as hypoxic conditions (15 mmHg) for 24 hours. Cell viability, function, hypoxia-induced changes in gene expression, and cytokine secretion were then assessed. Notably, hypoxia appeared to induce a decrease in viability and increasing islet density exacerbated the observed increase in cellular apoptosis as well as the loss of function. These changes were also associated with an increase in inflammatory gene transcription. Taken together, these data indicate that when a high number of islets are confined to a small space under hypoxia, cell viability and function are significantly impacted. Thus, in order to improve islet survival in this environment during transplantation, oxygenation is of critical importance. PMID:26824040

  14. Impact of Pancreatic Rat Islet Density on Cell Survival during Hypoxia.

    PubMed

    Rodriguez-Brotons, A; Bietiger, W; Peronet, C; Magisson, J; Sookhareea, C; Langlois, A; Mura, C; Jeandidier, N; Pinget, M; Sigrist, S; Maillard, E

    2016-01-01

    In bioartificial pancreases (BP), the number of islets needed to restore normoglycaemia in the diabetic patient is critical. However, the confinement of a high quantity of islets in a limited space may impact islet survival, particularly in regard to the low oxygen partial pressure (PO2) in such environments. The aim of the present study was to evaluate the impact of islet number in a confined space under hypoxia on cell survival. Rat islets were seeded at three different concentrations (150, 300, and 600 Islet Equivalents (IEQ)/cm(2)) and cultured in normal atmospheric pressure (160 mmHg) as well as hypoxic conditions (15 mmHg) for 24 hours. Cell viability, function, hypoxia-induced changes in gene expression, and cytokine secretion were then assessed. Notably, hypoxia appeared to induce a decrease in viability and increasing islet density exacerbated the observed increase in cellular apoptosis as well as the loss of function. These changes were also associated with an increase in inflammatory gene transcription. Taken together, these data indicate that when a high number of islets are confined to a small space under hypoxia, cell viability and function are significantly impacted. Thus, in order to improve islet survival in this environment during transplantation, oxygenation is of critical importance. PMID:26824040

  15. Whole-Cell Analysis of Low-Density Lipoprotein Uptake by Macrophages Using STEM Tomography

    PubMed Central

    Baudoin, Jean-Pierre; Jerome, W. Gray; Kübel, Christian; de Jonge, Niels

    2013-01-01

    Nanoparticles of heavy materials such as gold can be used as markers in quantitative electron microscopic studies of protein distributions in cells with nanometer spatial resolution. Studying nanoparticles within the context of cells is also relevant for nanotoxicological research. Here, we report a method to quantify the locations and the number of nanoparticles, and of clusters of nanoparticles inside whole eukaryotic cells in three dimensions using scanning transmission electron microscopy (STEM) tomography. Whole-mount fixed cellular samples were prepared, avoiding sectioning or slicing. The level of membrane staining was kept much lower than is common practice in transmission electron microscopy (TEM), such that the nanoparticles could be detected throughout the entire cellular thickness. Tilt-series were recorded with a limited tilt-range of 80° thereby preventing excessive beam broadening occurring at higher tilt angles. The 3D locations of the nanoparticles were nevertheless determined with high precision using computation. The obtained information differed from that obtained with conventional TEM tomography data since the nanoparticles were highlighted while only faint contrast was obtained on the cellular material. Similar as in fluorescence microscopy, a particular set of labels can be studied. This method was applied to study the fate of sequentially up-taken low-density lipoprotein (LDL) conjugated to gold nanoparticles in macrophages. Analysis of a 3D reconstruction revealed that newly up-taken LDL-gold was delivered to lysosomes containing previously up-taken LDL-gold thereby forming onion-like clusters. PMID:23383042

  16. Low-density lipoprotein-mediated delivery of docosahexaenoic acid selectively kills murine liver cancer cells

    PubMed Central

    Reynolds, Lacy; Mulik, Rohit S.; Wen, Xiaodong; Dilip, Archana; Corbin, Ian R.

    2014-01-01

    Aim The natural omega-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA), has recently been credited for possessing anticancer properties. Herein, we investigate the cytotoxic actions of DHA-loaded low-density lipoprotein (LDL) nanoparticles in normal and liver cancer cells. Materials & methods LDL-DHA nanoparticles were prepared and subjected to extensive biophysical characterization. The therapeutic utility of LDL-DHA nanoparticles was evaluated in normal and malignant murine hepatocyte cell lines, TIB-73 and TIB-75, respectively. Results & discussion The engineered LDL-DHA nanoparticles possessed enhanced physical and oxidative stabilities over native LDL and free DHA. Dose–response studies showed that therapeutic doses of LDL-DHA nanoparticles that completely killed TIB-75 were innocuous to TIB-73. The selective induction of lipid peroxidation and reactive oxygen species in the cancer cells was shown to play a central role in LDL-DHA nanoparticle-mediated cytotoxicity. Conclusion In summary, these findings indicate that LDL-DHA nanoparticles show great promise as a selective anticancer agent against hepatocellular carcinoma. PMID:24397600

  17. Automated computation of arbor densities: a step toward identifying neuronal cell types

    PubMed Central

    Sümbül, Uygar; Zlateski, Aleksandar; Vishwanathan, Ashwin; Masland, Richard H.; Seung, H. Sebastian

    2014-01-01

    The shape and position of a neuron convey information regarding its molecular and functional identity. The identification of cell types from structure, a classic method, relies on the time-consuming step of arbor tracing. However, as genetic tools and imaging methods make data-driven approaches to neuronal circuit analysis feasible, the need for automated processing increases. Here, we first establish that mouse retinal ganglion cell types can be as precise about distributing their arbor volumes across the inner plexiform layer as they are about distributing the skeletons of the arbors. Then, we describe an automated approach to computing the spatial distribution of the dendritic arbors, or arbor density, with respect to a global depth coordinate based on this observation. Our method involves three-dimensional reconstruction of neuronal arbors by a supervised machine learning algorithm, post-processing of the enhanced stacks to remove somata and isolate the neuron of interest, and registration of neurons to each other using automatically detected arbors of the starburst amacrine interneurons as fiducial markers. In principle, this method could be generalizable to other structures of the CNS, provided that they allow sparse labeling of the cells and contain a reliable axis of spatial reference. PMID:25505389

  18. Three-Dimensional Simulation of Ultrasound-Induced Microalgal Cell Disruption.

    PubMed

    Wang, M; Yuan, W; Hale, Andy

    2016-03-01

    The three-dimensional distribution (x, y, and z) of ultrasound-induced microalgal cell disruption in a sonochemical reactor was predicted by solving the Helmholtz equation using a three-dimensional acoustic module in the COMSOL Multiphysics software. The simulated local ultrasound pressure at any given location (x, y, and z) was found to correlate with cell disruption of a freshwater alga, Scenedesmus dimorphus, represented by the change of algal cell particle/debris concentration, chlorophyll-a fluorescence density (CAFD), and Nile red stained lipid fluorescence density (LFD), which was also validated by the model reaction of potassium iodide oxidation (the Weissler reaction). Furthermore, the effect of ultrasound power intensity and processing duration on algal cell disruption was examined to address the limitation of the model. PMID:26660670

  19. Bioconcentration kinetics of hydrophobic chemicals in different densities of Chlorella pyrenoidosa

    SciTech Connect

    Sijm, D.T.H.M.; Broersen, K.W.; Roode, D.F. de; Mayer, P.

    1998-09-01

    Algal density-dependent bioconcentration factors and rate constants were determined for a series of hydrophobic compounds in Chlorella pyrenoidosa. The apparent uptake rate constants of the hydrophobic compounds in algae varied between 200 and 710,000 L/kg/d, slightly increased with hydrophobicity within an experiment, were relatively constant for each algal density, and fitted fairly within existing allometric relationships. The bioavailability of the hydrophobic test compounds was significantly reduced by sorption by algal exudates. The sorption coefficients of the hydrophobic compounds to the algal exudates were between 80 and 1,200 L/kg, and were for most algal densities in the same order of magnitude as the apparent bioconcentration factors to the algae, that is, between 80 and 60,200 L/kg. In typical field situations, however, no significant reduction in bioavailability due to exudates is expected. The apparent elimination rate constants of the hydrophobic compounds were high and fairly constant for each algal density and varied between 2 and 190/d. Because the apparent elimination rate constants were higher than the growth rate constant, and were independent of hydrophobicity, the authors speculated that other factors dominate excretion, such as exudate excretion-enhanced elimination. Bioconcentration factors increased less than proportional with hydrophobicity, i.e., the octanol-water partition coefficient [K{sub ow}]. The role of algal composition in bioconcentration is evaluated. Bioconcentrations (kinetics) of hydrophobic compounds that are determined at high algal densities should be applied with caution to field situations.

  20. Influence of cations and anions on the induction of cell density-independent luminescence in Photorhabdus luminescens.

    PubMed

    Tabei, Yosuke; Ogawa, Akane; Era, Mariko; Ninomiya, Junko; Morita, Hiroshi

    2013-03-01

    Bioluminescence is emitted by various living organisms, including bacteria. While the induction mechanism in marine luminescent bacteria, such as Vibrio fischeri and V. harveyi, has been well characterized, this mechanism has not been studied in detail in the non-marine luminescent bacterium Photorhabdus luminescens. Therefore, we investigated the effect of cations and anions on the induction of luminescence by P. luminescens. Cultivation of cells in an inorganic salts solution (ISS) containing KCl, CaCl2 , MgCl2 , NaHCO3 , and MgSO4 resulted in a rapid increase in luminescence intensity. Moreover, the induction of luminescence in the ISS medium was not dependent on cell density, since cell densities remained unchanged during 48 h. Furthermore, we found that compounds containing K(+) , Mg(2+) , and HCO3(-) were necessary to induce cell density-independent luminescence. The intensity of luminescence per cell cultured in medium containing KCl, MgCl2 , and NaHCO3 was approximately 100-fold higher than that cultured in NB. In contrast, when cells actively grew in normal growth condition, the intensity of luminescence per cell was not increased even in the presence of K(+) , Mg(2+) , and HCO3(-) . Thus, these results suggest that the luminescence of P. luminescens is regulated by 2 independent cell density-dependent and -independent mechanisms. PMID:22733631

  1. Evaluation of anticoagulant activity of two algal polysaccharides.

    PubMed

    Faggio, C; Pagano, M; Dottore, A; Genovese, G; Morabito, M

    2016-09-01

    Marine algae are important sources of phycocolloids like agar, carrageenans and alginates used in industrial applications. Algal polysaccharides have emerged as an important class of bioactive products showing interesting properties. The aim of our study was to evaluate the potential uses as anticoagulant drugs of algal sulphate polysaccharides extracted from Ulva fasciata (Chlorophyta) and Agardhiella subulata (Rhodophyta) collected in Ganzirri Lake (Cape Peloro Lagoon, north-eastern Sicily, Italy). Toxicity of algal extracts through trypan blue test and anticoagulant action measured by activated partial thromboplastin time (APTT), prothrombin time (PT) test has been evaluated. Algal extracts showed to prolong the PT and APTT during the coagulation cascade and to avoid the blood coagulation of samples. Furthermore, the algal extracts lack toxic effects towards cellular metabolism and their productions are relatively at low cost. This permits to consider the algae as the biological source of the future. PMID:26360806

  2. The contribution of bacteria to algal growth by carbon cycling.

    PubMed

    Bai, Xue; Lant, Paul; Pratt, Steven

    2015-04-01

    Algal mass production in open systems is often limited by the availability of inorganic carbon substrate. In this paper, we evaluate how bacterial driven carbon cycling mitigates carbon limitation in open algal culture systems. The contribution of bacteria to carbon cycling was determined by quantifying algae growth with and without supplementation of bacteria. It was found that adding heterotrophic bacteria to an open algal culture dramatically enhanced algae productivity. Increases in algal productivity due to supplementation of bacteria of 4.8 and 3.4 times were observed in two batch tests operating at two different pH values over 7 days. A kinetic model is proposed which describes carbon limited algal growth, and how the limitation could be overcome by bacterial activity to re-mineralize photosynthetic end products. PMID:25312046

  3. Higher blood vessel density in comparison to the lymphatic vessels in oral squamous cell carcinoma

    PubMed Central

    Maturana-Ramírez, Andrea; Espinoza, Iris; Reyes, Montserrat; Aitken, Juan Pablo; Aguayo, Francisco; Hartel, Steffen; Rojas-Alcayaga, Gonzalo

    2015-01-01

    Introduction: Oral squamous cell carcinoma (OSCC) is characterized by local invasion and the development of cervical metastasis. In the tongue, an association between the invasion of the lymphatic vessels and the development of metastasis in the regional lymph nodes has been demonstrated. Moreover, invasion of the blood vessels is associated with greater recurrence and poorer prognoses. Therefore, the presence and density of lymphatic and blood vessels in intra- and peritumoral tissues should play an important role in the progression, dissemination and metastasis of carcinomas. However, the evidence regarding OSCC is inconclusive. The aim of this study was to determine the comparison and association between the lymphatic (D2-40) and blood vessel (CD34) densities in intratumoral OSCC tissue. Materials and Methods: Thirty-seven cases diagnosed as OSCC between the years 2000 and 2008 were obtained from the Anatomic Pathology Service of the School of Dentistry, University of Chile. The immunohistochemical markers D2-40 and CD34 were used, and the densities (mm2) of lymphatic vessels (LVD) and blood vessels (BVD) in the intratumoral region were determined. The relationship between LVD and BVD values was evaluated. Results: There were significant association between the CD34 and D2-40 expression (rho=0.4, P<0.05) and between the LVD and the location in the tongue (P=0.019). The BVD was greater (128.0 vessels/mm2) than the LVD (42.9 vessels/mm2), and there was a positive correlation between the LVD and BVD. Conclusions: In OSCC, the BVD is greater than the LVD, and there is a moderate correlation between the two quantities. PMID:26722595

  4. Cell Density Control of Staphylococcal Virulence Mediated by an Octapeptide Pheromone

    NASA Astrophysics Data System (ADS)

    Ji, Guangyong; Beavis, Ronald C.; Novick, Richard P.

    1995-12-01

    Some bacterial pathogens elaborate and secrete virulence factors in response to environmental signals, others in response to a specific host product, and still others in response to no discernible cue. In this study, we have demonstrated that the synthesis of Staphylococcus aureus virulence factors is controlled by a density-sensing system that utilizes an octapeptide produced by the organism itself. The octapeptide activates expression of the agr locus, a global regulator of the virulence response. This response involves the reciprocal regulation of genes encoding surface proteins and those encoding secreted virulence factors. As cells enter the postexponential phase, surface protein genes are repressed by agr and secretory protein genes are subsequently activated. The intracellular agr effector is a regulatory RNA, RNAIII, whose transcription is activated by an agr-encoded signal transduction system for which the octapeptide is the ligand.

  5. Optimization of high cell density fermentation process for recombinant nitrilase production in E. coli.

    PubMed

    Sohoni, Sujata Vijay; Nelapati, Dhanaraj; Sathe, Sneha; Javadekar-Subhedar, Vaishali; Gaikaiwari, Raghavendra P; Wangikar, Pramod P

    2015-01-01

    Nitrilases constitute an important class of biocatalysts for chiral synthesis. This work was undertaken with the aim to optimize nitrilase production in a host that is well-studied for protein production. Process parameters were optimized for high cell density fermentation, in batch and fed-batch modes, of Escherichia coli BL21 (DE3) expressing Pseudomonas fluorescens nitrilase with a T7 promoter based expression system. Effects of different substrates, temperature and isopropyl β-D-1-thiogalactopyranoside (IPTG) induction on nitrilase production were studied. Super optimal broth containing glycerol but without an inducer gave best results in batch mode with 32 °C as the optimal temperature. Use of IPTG led to insoluble protein and lower enzyme activity. Optimized fed-batch strategy resulted in significant improvement in specific activity as well as volumetric productivity of the enzyme. On a volumetric basis, the activity improved 40-fold compared to the unoptimized batch process. PMID:25739996

  6. High-cell-density fermentation for ergosterol production by Saccharomyces cerevisiae.

    PubMed

    Shang, Fei; Wen, Shaohong; Wang, Xi; Tan, Tianwei

    2006-01-01

    The direct feedback control of glucose using an on-line ethanol concentration monitor for ergosterol production by high-cell-density fermentation was investigated and the fermentation parameters (e.g., pH, dissolved oxygen, ethanol concentration, oxygen uptake rate, carbon dioxide evolution rate and respiratory quotient) were analyzed. Controlling glucose feeding rate in accordance with ethanol concentration and adjusting pH with ammonia during the fermentation process were effective fed-batch methods for ergosterol production. The fermentation parameters well described the variation of the whole fermentation process. Cultivation in a 5 l fermentor was carried out under the following conditions: culture temperature, 30 degrees C; pH, 5.5; agitation speed, 600 rpm; fermentation time, 60 h; controlling ethanol concentration below 1% and keeping respiratory quotient (RQ) at approximately 1.0. Under these conditions, the yeast dry weight reached 120 g/l and the ergosterol yield reached 1500 mg/l. PMID:16503289

  7. Control of microbial activity by flow injection analysis during high cell density cultivation of Escherichia coli.

    PubMed

    Ding, T; Bilitewski, U; Schmid, R D; Korz, D J; Sanders, E A

    1993-01-01

    The application of an automated flow injection analysis (FIA) system for on-line determination of microbial activity, during high cell density cultivations of Escherichia coli is reported. Based on a bioelectrochemical principle, the FIA method used a redox mediator (potassium hexacyanoferrate(III)) to facilitate electron transfer from the microorganisms to an electrochemical detector. Assays were carried out using a new sampling device which provided aseptic operation by use of a valve and chemical sterilisation. No sample dilution or pretreatment was necessary for biomass concentrations up to approx. 40 g l-1. The sample volume was 0.5 ml and the overall analysis time was 5 min. FIA signals were found to correlate well with the oxygen uptake rate (OUR). Changes in metabolic activity due to low substrate levels or high inhibitor concentrations in the cultivation medium became obvious from the FIA signals. PMID:7763463

  8. The Impact of Cathode Material and Shape on Current Density in an Aluminum Electrolysis Cell

    NASA Astrophysics Data System (ADS)

    Song, Yang; Peng, Jianping; Di, Yuezhong; Wang, Yaowu; Li, Baokuan; Feng, Naixiang

    2016-02-01

    A finite element model was developed to determine the impact of cathode material and shape on current density in an aluminum electrolysis cell. For the cathode material, results show that increased electrical resistivity leads to a higher cathode voltage drop; however, the horizontal current is reduced in the metal. The horizontal current magnitude for six different cathode materials in decreasing order is graphitized, semi-graphitized, full graphitic, 50% anthracite (50% artificial graphite), 70% anthracite (30% artificial graphite), 100% anthracite. The modified cathode shapes with an inclined cathode surface, higher collector bar and cylindrical protrusions are intended to improve horizontal current and flow resistance. Compared to a traditional cathode, modified collector bar sizes of 70 mm × 230 mm and 80 mm × 270 mm can reduce horizontal current density component Jx by 10% and 19%, respectively, due to better conductivity of the steel. The horizontal current in the metal decreases with increase of cathode inclination. The peak value of Jx can be approximately reduced by 20% for a 2° change in inclination. Cylindrical protrusions lead to local horizontal current increase on their tops, but the average current is less affected and the molten metal is effectively slowed down.

  9. Detection of surface algal blooms using the newly developed algorithm surface algal bloom index (SABI)

    NASA Astrophysics Data System (ADS)

    Alawadi, Fahad

    2010-10-01

    Quantifying ocean colour properties has evolved over the past two decades from being able to merely detect their biological activity to the ability to estimate chlorophyll concentration using optical satellite sensors like MODIS and MERIS. The production of chlorophyll spatial distribution maps is a good indicator of plankton biomass (primary production) and is useful for the tracing of oceanographic currents, jets and blooms, including harmful algal blooms (HABs). Depending on the type of HABs involved and the environmental conditions, if their concentration rises above a critical threshold, it can impact the flora and fauna of the aquatic habitat through the introduction of the so called "red tide" phenomenon. The estimation of chlorophyll concentration is derived from quantifying the spectral relationship between the blue and the green bands reflected from the water column. This spectral relationship is employed in the standard ocean colour chlorophyll-a (Chlor-a) product, but is incapable of detecting certain macro-algal species that float near to or at the water surface in the form of dense filaments or mats. The ability to accurately identify algal formations that sometimes appear as oil spill look-alikes in satellite imagery, contributes towards the reduction of false-positive incidents arising from oil spill monitoring operations. Such algal formations that occur in relatively high concentrations may experience, as in land vegetation, what is known as the "red-edge" effect. This phenomena occurs at the highest reflectance slope between the maximum absorption in the red due to the surrounding ocean water and the maximum reflectance in the infra-red due to the photosynthetic pigments present in the surface algae. A new algorithm termed the surface algal bloom index (SABI), has been proposed to delineate the spatial distributions of floating micro-algal species like for example cyanobacteria or exposed inter-tidal vegetation like seagrass. This algorithm was

  10. ALGAL NUTRIENT AVAILABILITY AND LIMITATION IN LAKE ONTARIO DURING IFYGL. PART III. ALGAL NUTRIENT LIMITATION IN LAKE ONTARIO DURING IFYGL

    EPA Science Inventory

    This study was conducted on the potential significance of nitrogen, phosphorus and micronutrients in limiting planktonic algal growth in Lake Ontario and its major tributaries. Standard algal assay procedures were used. Samples of the open waters of Lake Ontario and Niagara River...

  11. Inducing the migration behavior of endothelial cells by tuning the ligand density on a density-gradient poly(ethylene glycol) surface.

    PubMed

    Li, Tiantian; Xu, Kui; Fu, Ya; Cai, Kaiyong

    2016-07-01

    The migration of endothelial cells (ECs) is crucially important for many biological processes, including early embryonic vasculogenesis, wound healing and angiogenesis. To investigate the effect of the surface poly(ethylene glycol) (mPEG-CHO) density on the migration of ECs, we developed a convenient and effective method to fabricate a series of silicon slides with graded PEG densities on their surfaces based on gradual treatment with 3-glycidoxypropyltrimethoxysilane (GPTMS), backfilling with 3-aminopropyltriethoxysilane (APTES) and subsequent conjugation of m-PEG. The PEG gradient was confirmed by X-ray photoelectron spectrometry (XPS), contact angle measurement and spectroscopic ellipsometry and determined to range from 0.56 to 0.75chains/nm(2). The impact of the PEG gradient on the EC migration was evaluated by real-time observation via a time-lapse phase-contrast microscope. ECs adhered to the silicon surfaces with high and modest PEG densities displayed a higher tendency of migration than those on corresponding non-graded samples. The results suggest that the motility of ECs could be modulated by the PEG gradient. This study would be helpful for understanding cell-substrate interactions. PMID:27058513

  12. Density Gradient Centrifugation for the Isolation of Cells of Multiple Lineages.

    PubMed

    Yamamoto, Yumiko; Itoh, Shousaku; Yamauchi, Yukako; Matsushita, Kenta; Ikeda, Shun; Naruse, Haruna; Hayashi, Mikako

    2015-12-01

    We recently developed a simple strategy for the enrichment of mesenchymal stem cells (MSCs) with the capacity for osteoblast, chondrocyte, and adipocyte differentiation. On transplantation, the progenitor-enriched fraction can regenerate bone with multiple lineages of donor origin. Although comprising multiple precursor cell types, the population is enriched >100-fold in osteoprogenitors, hence the name "highly purified osteoprogenitors" (HipOPs). To establish a new modified method of purifying pure MSCs, it is useful to know the expression patterns of surface markers on heterogeneous MSCs and committed cells such as osteoblasts, adipocytes, and chondrocytes. However, calcium deposition by osteoblasts is a critical obstacle in visualizing the expression patterns of surface markers. We now report a new method of separating differentiated osteoblastic HipOPs (OB-HipOPs) from calcium deposits using the Percoll density gradient centrifugation technique. After centrifuge separation, calcium deposits were observed at the bottom of the centrifuge tube, and living OB-HipOPs were harvested from the 10-70% fractions. However, there were no living cells in the 70-80% fraction. We concluded that living OB-HipOPs are separated by one 10-70% Percoll gradient. Furthermore, we analyzed the expression patterns of putative MSC markers on differentiated HipOPs. FACS analysis revealed that Sca-1, CD44, CD73, CD105, and CD106 were decreased in OB-HipOPs. In adipogenic- and chondrogenic-HipOPs, Sca-1, CD73, CD105, and CD106 were decreased. This new technique is a helpful tool to identify MSC surface markers and to clarify in more detail the differentiation stages of osteoblasts. PMID:26105044

  13. Manifestations of type 2 diabetes in corneal endothelial cell density, corneal thickness and intraocular pressure

    PubMed Central

    Briggs, Stella; Osuagwu, Uchechukwu L; AlHarthi, Essam M

    2016-01-01

    Abstract We sought to evaluate central corneal thickness (CCT), corneal endothelial cell density (ECD) and intraocular pressure (IOP) in patients with type 2 diabetes mellitus (DM) and to associate potential differences with diabetes duration and treatment modality in a prospective, randomized study. We measured ECD, CCT and IOP of 125 patients with type 2 DM (mean age 57.1±11.5 years) and compared them with 90 age-matched controls. Measured parameters were analyzed for association with diabetes duration and glucose control modalities (insulin injection or oral medication) while controlling for age. In the diabetic group, the mean ECD (2511±252 cells/mm2), mean CCT (539.7±33.6 µm) and mean IOP (18.3±2.5 mmHg) varied significantly from those the control group [ECD: 2713±132 cells/mm2 (P<0.0001), CCT: 525.0±45.3 µm (P=0.003) and IOP: 16.7±1.8 mmHg (P<0.0001)]. ECD was significantly reduced by about 32 cell/mm2 for diabetics with duration of >10 years when compared with those with duration of <10 years (P<0.05). CCT was thicker and IOP was higher for diabetics with duration of >10 years than those with duration of <10 years (P>0.05). None of the measured parameters was significantly associated with diabetes duration and treatment modality (P>0.05). In conclusion, subjects with type 2 DM exhibit significant changes in ECD, IOP and CCT, which, however, are not correlated with disease duration or if the patients receive on insulin injection or oral medications.

  14. A bio-anodic filter facilitated entrapment, decomposition and in situ oxidation of algal biomass in wastewater effluent.

    PubMed

    Mohammadi Khalfbadam, Hassan; Cheng, Ka Yu; Sarukkalige, Ranjan; Kaksonen, Anna H; Kayaalp, Ahmet S; Ginige, Maneesha P

    2016-09-01

    This study examined for the first time the use of bioelectrochemical systems (BES) to entrap, decompose and oxidise fresh algal biomass from an algae-laden effluent. The experimental process consisted of a photobioreactor for a continuous production of the algal-laden effluent, and a two-chamber BES equipped with anodic graphite granules and carbon-felt to physically remove and oxidise algal biomass from the influent. Results showed that the BES filter could retain ca. 90% of the suspended solids (SS) loaded. A coulombic efficiency (CE) of 36.6% (based on particulate chemical oxygen demand (PCOD) removed) was achieved, which was consistent with the highest CEs of BES studies (operated in microbial fuel cell mode (MFC)) that included additional pre-treatment steps for algae hydrolysis. Overall, this study suggests that a filter type BES anode can effectively entrap, decompose and in situ oxidise algae without the need for a separate pre-treatment step. PMID:27268438

  15. High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

    SciTech Connect

    Wolfe, Adam R.; Atkinson, Rachel L.; Reddy, Jay P.; Debeb, Bisrat G.; Larson, Richard; Li, Li; Masuda, Hiroko; Brewer, Takae; Atkinson, Bradley J.; Brewster, Abeena; Ueno, Naoto T.; Woodward, Wendy A.

    2015-04-01

    Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients

  16. Changes in small intestinal chromogranin A-immunoreactive cell densities in patients with irritable bowel syndrome after receiving dietary guidance.

    PubMed

    Mazzawi, Tarek; El-Salhy, Magdy

    2016-05-01

    Chromogranin A (CgA) is a common marker for enteroendocrine cells in the gut, and CgA-immunoreactive cell densities are abnormal in patients with irritable bowel syndrome (IBS). The majority of patients with IBS report that their symptoms develop after consuming certain foodstuffs. In the present study, we investigated the effects of dietary guidance on the total enteroendocrine cell densities in the small intestine, as detected by CgA. A total of 14 patients with IBS underwent a gastroscopy with duodenal biopsies and 11 of them also underwent a colonoscopy, with biopsy samples obtained from the ileum. Fourteen control subjects were also included. Each patient received 3 sessions of dietary guidance. Gastroscopies and colonoscopies were performed on both the controls and patients with IBS (at baseline and at 3-9 months after receiving guidance). Biopsy samples obtained from the duodenum and ileum were immunostained for CgA using the avidin-biotin complex (ABC) method and were quantified using computerized image analysis. The density of CgA-immunoreactive cells in the duodenum (mean ± SEM values) in the control subjects was 235.9 ± 31.9 cells/mm2; in the patients with IBS, the density was 36.9 ± 9.8 and 103.7 ± 16.9 cells/mm2 before and after they received dietary guidance, respectively (P=0.007). The density of CgA-immunoreactive cells in the ileum in the control subjects was 47.4 ± 8.3 cells/mm2; in the patients with IBS, the density was 48.4 ± 8.1 and 17.9 ± 4.4 cells/mm2, before and after they received dietary guidance, respectively (P=0.0006). These data indicate that changes in CgA-immunoreactive cell densities in patients with IBS after receiving dietary guidance may reflect a change in the densities of the small intestinal enteroendocrine cells, which may contribute to an improvement in the IBS symptoms. PMID:26987104

  17. Changes in small intestinal chromogranin A-immunoreactive cell densities in patients with irritable bowel syndrome after receiving dietary guidance

    PubMed Central

    MAZZAWI, TAREK; EL-SALHY, MAGDY

    2016-01-01

    Chromogranin A (CgA) is a common marker for enteroendocrine cells in the gut, and CgA-immunoreactive cell densities are abnormal in patients with irritable bowel syndrome (IBS). The majority of patients with IBS report that their symptoms develop after consuming certain foodstuffs. In the present study, we investigated the effects of dietary guidance on the total enteroendocrine cell densities in the small intestine, as detected by CgA. A total of 14 patients with IBS underwent a gastroscopy with duodenal biopsies and 11 of them also underwent a colonoscopy, with biopsy samples obtained from the ileum. Fourteen control subjects were also included. Each patient received 3 sessions of dietary guidance. Gastroscopies and colonoscopies were performed on both the controls and patients with IBS (at baseline and at 3–9 months after receiving guidance). Biopsy samples obtained from the duodenum and ileum were immunostained for CgA using the avidin-biotin complex (ABC) method and were quantified using computerized image analysis. The density of CgA-immunoreactive cells in the duodenum (mean ± SEM values) in the control subjects was 235.9±31.9 cells/mm2; in the patients with IBS, the density was 36.9±9.8 and 103.7±16.9 cells/mm2 before and after they received dietary guidance, respectively (P=0.007). The density of CgA-immunoreactive cells in the ileum in the control subjects was 47.4±8.3 cells/mm2; in the patients with IBS, the density was 48.4±8.1 and 17.9±4.4 cells/mm2, before and after they received dietary guidance, respectively (P=0.0006). These data indicate that changes in CgA-immunoreactive cell densities in patients with IBS after receiving dietary guidance may reflect a change in the densities of the small intestinal enteroendocrine cells, which may contribute to an improvement in the IBS symptoms. PMID:26987104

  18. Algal populations controlled by fish herbivory across a wave exposure gradient on southern temperate shores.

    PubMed

    Taylor, David I; Schiel, David R

    2010-01-01

    vertebrate consumers are rare and were mediated by an environmental gradient and plant density, both of which interact with algal demographics. The study highlights that, even though herbivorous fish diversity may be low, the impacts of particular species may still be high, even in cool temperate waters where fish herbivory is usually considered to be minimal. PMID:20380209

  19. Degradation of algal lipids by deep-sea benthic foraminifera: An in situ tracer experiment

    NASA Astrophysics Data System (ADS)

    Nomaki, Hidetaka; Ohkouchi, Naohiko; Heinz, Petra; Suga, Hisami; Chikaraishi, Yoshito; Ogawa, Nanako O.; Matsumoto, Kouhei; Kitazato, Hiroshi

    2009-09-01

    We conducted an in situ feeding experiment using 13C-labeled unicellular algae in Sagami Bay, Japan (water depth, 1450 m), in order to understand the fate of lipid compounds in phytodetritus at the deep-sea floor. We examined the incorporation of excess 13C into lipid compounds extracted from bulk sediments and benthic foraminiferal cells. 13C-enriched fatty acids derived from 13C-labeled algae were exponentially degraded during 6 days of incubation in the sediment. Subsequent enrichments in 13C in sedimentary n-C 15,anteiso-C 17, and C 17 fatty acids indicated the microbial degradation of algal material and production of bacterial biomass in the sediment. We observed the incorporation of 13C-labeled algal phytol and fatty acids into foraminiferal cells. The compositions of 13C-labeled algal lipids in foraminiferal cells were different from those in the bulk sediments, indicating that foraminiferal feeding and digestion influenced the lipid distribution in the sediments. Furthermore, some sterols in Globobulimina affinis (e.g., 24-ethylcholesta-5,22-dien-3β-ol, 24-ethylcholest-5-en-3β-ol, and 23,24-dimethylcholesta-5,22E-dien-3β-ol) were newly produced via the modification of dietary algal sterols within 4-6 days. In addition to the effects of bacteria, feeding by benthic foraminifera can result in a significant reorganization of the composition of organic matter and influence benthic food webs and carbon cycling at the deep-sea floor.

  20. Effectiveness of electroacupuncture at Zusanli (ST36) on the immunohistochemical density of enteroendocrine cells related to gastrointestinal function.