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961.
During bioethanol fermentation process, Saccharomyces cerevisiae cell membrane might provide main protection to tolerate accumulated ethanol, and S. cerevisiae cells might also remodel their membrane compositions or structure to try to adapt to or tolerate the ethanol stress. However, the exact changes and roles of S. cerevisiae cell membrane components during bioethanol fermentation still remains poorly understood. This study was performed to clarify changes and roles of S. cerevisiae cell membrane components during bioethanol fermentation. Both cell diameter and membrane integrity decreased as fermentation time lasting. Moreover, compared with cells at lag phase, cells at exponential and stationary phases had higher contents of ergosterol and oleic acid (C18:1) but lower levels of hexadecanoic (C16:0) and palmitelaidic (C16:1) acids. Contents of most detected phospholipids presented an increase tendency during fermentation process. Increased contents of oleic acid and phospholipids containing unsaturated fatty acids might indicate enhanced cell membrane fluidity. Compared with cells at lag phase, cells at exponential and stationary phases had higher expressions of ACC1 and HFA1. However, OLE1 expression underwent an evident increase at exponential phase but a decrease at following stationary phase. These results indicated that during bioethanol fermentation process, yeast cells remodeled membrane and more changeable cell membrane contributed to acquiring higher ethanol tolerance of S. cerevisiae cells. These results highlighted our knowledge about relationship between the variation of cell membrane structure and compositions and ethanol tolerance, and would contribute to a better understanding of bioethanol fermentation process and construction of industrial ethanologenic strains with higher ethanol tolerance. 相似文献
962.
963.
Reflections on agricultural landscape revegetation in south‐eastern Australia: Interview with Martin Driver
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One of Australia's leading on‐ground extension officers describes the successes and lessons learned in The Riverina's native revegetation movement over the 20–25 years – but warns of potential failure of current and future Australian revegetation programs if greater funding security is not delivered. 相似文献
964.
Social insect colonies can be seen as a distinct form of biological organisation because they function as superorganisms. Understanding how natural selection acts on the emergence and maintenance of these colonies remains a major question in evolutionary biology and ecology. Here, we explore this by using multi‐type branching processes to calculate the basic reproductive ratios and the extinction probabilities for solitary vs. eusocial reproductive strategies. We find that eusociality, albeit being hugely successful once established, is generally less stable than solitary reproduction unless large demographic advantages of eusociality arise for small colony sizes. We also demonstrate how such demographic constraints can be overcome by the presence of ecological niches that strongly favour eusociality. Our results characterise the risk‐return trade‐offs between solitary and eusocial reproduction, and help to explain why eusociality is taxonomically rare: eusociality is a high‐risk, high‐reward strategy, whereas solitary reproduction is more conservative. 相似文献
965.
Habitat destruction is driving biodiversity loss in remaining ecosystems, and ecosystem functioning and services often directly depend on biodiversity. Thus, biodiversity loss is likely creating an ecosystem service debt: a gradual loss of biodiversity‐dependent benefits that people obtain from remaining fragments of natural ecosystems. Here, we develop an approach for quantifying ecosystem service debts, and illustrate its use to estimate how one anthropogenic driver, habitat destruction, could indirectly diminish one ecosystem service, carbon storage, by creating an extinction debt. We estimate that c. 2–21 Pg C could be gradually emitted globally in remaining ecosystem fragments because of plant species loss caused by nearby habitat destruction. The wide range for this estimate reflects substantial uncertainties in how many plant species will be lost, how much species loss will impact ecosystem functioning and whether plant species loss will decrease soil carbon. Our exploratory analysis suggests that biodiversity‐dependent ecosystem service debts can be globally substantial, even when locally small, if they occur diffusely across vast areas of remaining ecosystems. There is substantial value in conserving not only the quantity (area), but also the quality (biodiversity) of natural ecosystems for the sustainable provision of ecosystem services. 相似文献
966.
PsMPK7, a stress‐associated mitogen‐activated protein kinase (MAPK) in Phytophthora sojae,is required for stress tolerance,reactive oxygenated species detoxification,cyst germination,sexual reproduction and infection of soybean
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967.
Johan De Vogel-van den Bosch Sjoerd A.A. van den Berg Silvia BijlandPeter J. Voshol Louis M. Havekes Hans A. RomijnJoris Hoeks Denis van Beurden Matthijs K.C. HesselinkPatrick Schrauwen Ko Willems van Dijk 《The Journal of nutritional biochemistry》2011,22(4):366-371
Excess dietary long-chain fatty acid (LCFA) intake results in ectopic lipid accumulation and insulin resistance. Since medium-chain fatty acids (MCFA) are preferentially oxidized over LCFA, we hypothesized that diets rich in MCFA result in a lower ectopic lipid accumulation and insulin resistance compared to diets rich in LCFA. Feeding mice high-fat (HF) (45% kcal fat) diets for 8 weeks rich in triacylglycerols composed of MCFA (HFMCT) or LCFA (HFLCT) revealed a lower body weight gain in the HFMCT-fed mice. Indirect calorimetry revealed higher fat oxidation on HFMCT compared to HFLCT (0.011.0±0.0007 vs. 0.0096±0.0015 kcal/g body weight per hour, P<.05). In line with this, neutral lipid immunohistochemistry revealed significantly lower lipid storage in skeletal muscle (0.05±0.08 vs. 0.30±0.23 area%, P <.05) and in liver (0.9±0.4 vs. 6.4±0.8 area%, P<.05) after HFMCT vs. HFLCT, while ectopic fat storage in low fat (LF) was very low. Hyperinsulinemic euglycemic clamps revealed that the HFMCT and HFLCT resulted in severe whole body insulin resistance (glucose infusion rate: 53.1±6.8, 50.8±15.3 vs. 124.6±25.4 μmol min−1 kg−1, P<.001 in HFMCT, HFLCT and LF-fed mice, respectively). However, under hyperinsulinemic conditions, HFMCT revealed a lower endogenous glucose output (22.6±8.0 vs. 34.7±8.5 μmol min−1 kg−1, P<.05) and a lower peripheral glucose disappearance (75.7±7.8 vs. 93.4±12.4 μmol min−1 kg−1, P<.03) compared to HFLCT-fed mice. In conclusion, both HF diets induced whole body insulin resistance compared to LF. However, the HFMCT gained less weight, had less ectopic lipid accumulation, while peripheral insulin resistance was more pronounced compared to HFLCT. This suggests that HF-diets rich in medium- versus long-chain triacylglycerols induce insulin resistance via distinct mechanisms. 相似文献
968.
The effects of hematite nanoparticles concentration (0-1600 mg/L) and initial pH (4.0-10.0) on hydrogen production were investigated in batch assays using sucrose-fed anaerobic mixed bacteria at 35 °C. The optimum hematite nanoparticles concentration with an initial pH 8.48 was 200 mg/L, with the maximum hydrogen yield of 3.21 mol H2/mol sucrose which was 32.64% higher than the blank test. At 200 mg/L hematite nanoparticles concentration, further initial pH optimization experiments indicated that at pH 6.0 the maximum hydrogen yield reached to 3.57 mol H2/mol sucrose and hydrogen content was 66.1%. The slow release of hematite nanoparticles had been recorded by transmission electron microscopy (TEM). In addition, TEM analysis indicated that the hematite nanoparticles can affect the shape of bacteria, namely, its length increased from ca. 2.0-3.6 μm to ca. 2.6-5.6 μm, and width became narrower. 相似文献
969.
In this study, a lab-scale serial photobioreactor composed of three column reactors was constructed and continuously operated to investigate several parameters influencing photohydrogen production when using the synthetic wastewater and the anaerobic hydrogen fermentation effluents as the influents. The results indicated that better hydrogen production rate was obtained when the serial photobioreactor was operated under cellular recycling at a short HRT of 8 h. The serial photobioreactor maintained high hydrogen content ca. 80% in the produced gas and 0.4× dilution ratio was the suitable ratio for hydrogen production. When the photobioreactor fed with the real wastewater (Effluent 1) containing 100 mg/L NH4Cl, Column 1 reactor successfully reduced ammonia concentration to about 60 mg/L for cell synthesis, resulting in a steady hydrogen production in the following two column reactors. The average hydrogen production rate was 205 mL-H2/L/d. 相似文献
970.
Steam reforming of two kinds of bio-oil from rice husks fast pyrolysis was conducted for hydrogen production at three temperatures (650, 750 and 850 °C) with Ni-based catalyst in a fixed-bed reactor. The gas composition and organic compounds in liquid condensate were detected by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), respectively. In addition, the carbon deposition was also investigated. The results showed that the mole fraction range of hydrogen was within 55.8-61.3% at all temperatures and more hydrogen was produced at the higher temperature. The highest H? efficiency of bio-oil steam reforming was 45.33% when extra water was added. The bio-oil with lower content of chemical compounds has a higher H? efficiency, but its hydrogen volume was less. Analysis of the liquid condensate showed that most of the organic compounds were circularity compounds. The carbon deposition can decrease the bio-oil conversion, and it was easier to form at the temperature of 750 °C. 相似文献