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1.
Summary
Bacillus stearothermophilus was adapted to grow at 55°C and 37°C in a complex medium with almost equivalent yields in cell mass. In both temperature
ranges the maximum specific growth rates (μmax) were identical.
Cellular extracts of this bacterium showed remarkable differences in the activity levels of several enzymes, depending on
the respective growth temperature.
High activities of glyceraldehyde-3-phosphate dehydrogenase and alcohol dehydrogenase were observed in bacteria from thermophilic
cultures (55°C) and the respiratory quotient exceeded 1.0. Under anaerobic conditions at 55°C μmax was the same as in aerobic cultures.
No alcohol dehydrogenase was detected in cells from mesophilic cultures (37°C), however, and the level of glyceraldehyde-3-phosphate
dehydrogenase was also extremely low under mesophilic conditions. Succinate dehydrogenase and isocitrate dehydrogenase activity
appeared to be higher in bacteria grown at 37°C; the resspiratory quotient was always lower than 1.0.
At 37°C, acetoin formation was observed regularly, a fermentation product which was never detected in 55°C-cultures. Under
anaerobic conditions at 37°C a very low growth rate was found. When adapted to grow at 37°C or 55°C,B. stearothermophilus is apparently able to use different catabolic systems. 相似文献
2.
3.
The rate of synthesis and degradation of phospholipids in Mycobacterium smegmatis ATCC 607, grown at 27° C and 37° C was studied by incorporation of 32P into phospholipids and chase of radioactivity of the pulse-labelled phospholipids. A relatively low rate of synthesis and
degradation of phospholipids in cells growth at 27° C was observed as compared to those grown at 37° C. Phosphatidylethanolamine
(PE) had the maximum turnover at 37° C. However, at 27° C, cardiolipin (CL) showed a turnover rate higher than PE. Phosphatidylinositol
mannosides (PIMs) were metabolically more active at 37° C than at 27° C. The differences in metabolic activity of the phospholipids
at the two temperatures have been discussed. 相似文献
4.
K. Hamdorf L. R. Keller 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1962,45(6):711-724
Zusammenfassung Die Formveränderungen des Elektroretinogramms von Calliphora werden bei Gefrierung auf —10 ° C und anschließender Erwärmung untersucht.Mehrmaliges Gefrieren auf —10 ° C und Auftauen wird vom Fliegenauge ohne erkennbare Schädigung überstanden.Während des Gefrierens wird zunächst der zeitliche Ablauf des Retinogramms verzögert, die Amplituden der Teilpotentiale nehmen ab und die positiven Komponenten verschwinden schließlich.Noch bei — 6,5° C (bzw. —10 ° C) läßt sich ein negatives Potential nachweisen, dessen Latenz und Amplitude stark temperaturabhängig sind. Es ist sehr wahrscheinlich mit dem Generatorpotential identisch.Bei langsamer oder schneller Erwärmung treten die positiven Komponenten wieder im Retinogramm auf und entwickeln sich bis zur normalen Höhe.Ein-und Auseffekt lassen sich durch die Kältebehandlung in mehrere Teilpotentiale zerlegen.Der Auseffekt wird möglicherweise von ähnlichen morphologischen Strukturen erzeugt wie der positive Eineffekt. 相似文献
5.
The aim of this investigation was to elucidate the reductions in muscle, skin and core temperature following exposure to −110°C whole body cryotherapy (WBC), and compare these to 8°C cold water immersion (CWI). Twenty active male subjects were randomly assigned to a 4-min exposure of WBC or CWI. A minimum of 7 days later subjects were exposed to the other treatment. Muscle temperature in the right vastus lateralis (n = 10); thigh skin (average, maximum and minimum) and rectal temperature (n = 10) were recorded before and 60 min after treatment. The greatest reduction (P<0.05) in muscle (mean ± SD; 1 cm: WBC, 1.6±1.2°C; CWI, 2.0±1.0°C; 2 cm: WBC, 1.2±0.7°C; CWI, 1.7±0.9°C; 3 cm: WBC, 1.6±0.6°C; CWI, 1.7±0.5°C) and rectal temperature (WBC, 0.3±0.2°C; CWI, 0.4±0.2°C) were observed 60 min after treatment. The largest reductions in average (WBC, 12.1±1.0°C; CWI, 8.4±0.7°C), minimum (WBC, 13.2±1.4°C; CWI, 8.7±0.7°C) and maximum (WBC, 8.8±2.0°C; CWI, 7.2±1.9°C) skin temperature occurred immediately after both CWI and WBC (P<0.05). Skin temperature was significantly lower (P<0.05) immediately after WBC compared to CWI. The present study demonstrates that a single WBC exposure decreases muscle and core temperature to a similar level of those experienced after CWI. Although both treatments significantly reduced skin temperature, WBC elicited a greater decrease compared to CWI. These data may provide information to clinicians and researchers attempting to optimise WBC and CWI protocols in a clinical or sporting setting. 相似文献
6.
Microbial reductive dechlorination of [1,2-14C]trichloroethene to [14C]cis-dichloroethene and [14C]vinyl chloride was observed at 4°C in anoxic microcosms prepared with cold temperature-adapted aquifer and river sediments from Alaska. Microbial anaerobic oxidation of [1,2-14C]cis-dichloroethene and [1,2-14C]vinyl chloride to 14CO2 also was observed under these conditions. 相似文献
7.
There is great interest in achieving reproducibly high survivals of mammalian oocytes (especially human) after cryopreservation, but the results to date have not matched the interest. A prime cause of cell death is the formation of more than trace amounts of intracellular ice, and one strategy to avoid it is vitrification. In vitrification procedures, cells are loaded with high concentrations of glass-inducing solutes and cooled to −196 °C at rates high enough to presumably induce the glassy state. In the last decade, several devices have been developed to achieve very high cooling rates. Nearly all in the field have assumed that the cooling rate is the critical factor. The purpose of our study was to test that assumption by examining the consequences of cooling mouse oocytes in a vitrification solution at four rates ranging from 95 to 69,250 °C/min to −196 °C and for each cooling rate, subjecting them to five warming rates back above 0 °C at rates ranging from 610 to 118,000 °C/min. In samples warmed at the highest rate (118,000 °C/min), survivals were 70% to 85% regardless of the prior cooling rate. In samples warmed at the lowest rate (610 °C/min), survivals were low regardless of the prior cooling rate, but decreased from 25% to 0% as the cooling rate was increased from 95 to 69,000 °C/min. Intermediate cooling and warming rates gave intermediate survivals. The especially high sensitivity of survival to warming rate suggests that either the crystallization of intracellular glass during warming or the growth by recrystallization of small intracellular ice crystals formed during cooling are responsible for the lethality of slow warming. 相似文献
8.
The growth of dermatophytes at 4° C and 37° C; The relation of this character to others 总被引:1,自引:1,他引:0
Summary The ability of the generaEpidermophyton, Microsporon andTrichopyton to grow on some media at 4° C and 37° C was studied. It has been shown that specific differences exist among these fungi in the capability or rapidity of the growth at extreme temperatures.There is high positive correlation among perfect state production, isolation from the soil and growth at 4° C (group of characters A) and between pathogenicity and growth at 37° C (group of characters B). Between the groups A and B of characters exists a slighter negative correlation. Some prognosis about the five characters by certain species of dermatophytes may be given. 相似文献
9.
10.
J.N. Laverriere D. Gourdji R. Picart A. Tixier-Vidal 《Biochemical and biophysical research communications》1981,103(3):833-840
The time-course of thyroliberin transfer to the nucleus of GH3/B6 rat pituitary prolactin cells was studied by both autoradiography and cell fractionation of intact cells exposed to [3H]thyroliberin at 4°C or 37°C. It was previously shown that thyroliberin is not degraded in these conditions. It is found by autoradiography that [3H]-thyroliberin is transferred to the nucleus of GH3/B6 cells within 5 min at least at both 37° C and 4°C. Consistent results are obtained by fractionation of cells exposed to [3H]thyroliberin at 37°C. However after binding at 4°C 50% of the cell radioactivity is extractible by glutaraldehyde and after fractionation the isolated nuclei retain only 1–1.5% of the cell radioactivity. This suggests the existence of both tightly bound and loosely bound internalized thyroliberin molecules. 相似文献
11.
Marta Goberna Maria Gadermaier Carlos García Bernhard Wett Heribert Insam 《Applied and environmental microbiology》2010,76(19):6564-6571
The acclimatization of methanogens to two-phase olive mill wastes (TPOMW) was investigated in pilot fermenters started up with cattle excreta (37°C) and after changing their feed to excreta plus TPOMW (37°C or 55°C) or TPOMW alone (37°C) until a steady state was reached (28 days). Methanogenic diversity was screened using a phylogenetic microarray (AnaeroChip), and positive targets were quantified by real-time PCR. Results revealed high phylogenetic richness, with representatives of three out of the four taxonomic orders found in digesters. Methanosarcina dominated in the starting excreta (>96% of total 16S rRNA gene copies; over 45 times more abundant than any other methanogen) at high acetate (0.21 g liter−1) and ammonia N concentrations (1.3 g liter−1). Codigestion at 37°C induced a 6-fold increase of Methanosarcina numbers, correlated with CH4 production (rPearson = 0.94; P = 0.02). At 55°C, the rise in temperature and H2 partial pressure induced a burst of Methanobacterium, Methanoculleus, Methanothermobacter, and a group of uncultured archaea. The digestion of excreta alone resulted in low but constant biogas production despite certain oscillations in the methanogenic biomass. Unsuccessful digestion of TPOMW alone was attributed to high Cu levels inducing inhibition of methanogenic activity. In conclusion, the versatile Methanosarcina immediately adapted to the shift from excreta to excreta plus TPOMW and was responsible for the stimulated CH4 production at 37°C. Higher temperatures (55°C) fostered methanogenic diversity by promoting some H2 scavengers while yielding the highest CH4 production. Further testing is needed to find out whether there is a link between increased methanogenic diversity and reactor productivity.Turning residues into energy is a societal and scientific priority due to climate change, fossil fuel exhaustion, and waste accumulation. In 2006, in Europe (EU27), less than 3% of electricity production came from biomass and wastes (11). Biogas plants, which anaerobically treat organic wastes to produce energy, are increasingly promoted in Europe, but their distribution is highly biased (35). While thousands of full- and farm-scale biogas plants are spread over central and northern Europe, anaerobic digestion technology in Mediterranean countries—Portugal, Spain, Italy, Greece, and Turkey—is in its early stages (35). These nations and other circum-Mediterranean countries lead in the production of olive oil and thus in olive mill wastes and wastewaters, which have a huge biogas production potential due to their lipid composition (1). Spain alone generates one-third of the world''s oil production and millions of tons of two-phase olive mill wastes (TPOMW) per year. TPOMW are mostly burned or composted (28), hence releasing methane into the atmosphere. This compels a change in strategy: methane production from TPOMW should be optimized in engineered environments and transformed into energy.TPOMW is a humid residue containing the olive pulp and stone. Its anaerobic digestibility is hampered by its low pH, low ammonia N, and high content in antimicrobial substances (1). However, it has been successfully fermented under laboratory conditions by supplementing it with nutrients and increasing the reactor organic loading rate stepwise (2) or by codigesting it with residues with a high buffering capacity, e.g., cattle excreta (17). These approaches seem to facilitate the adaptation of the methane-producing anaerobic community to the environmental conditions that TPOMW impose.Methanogenic archaea—microbes clustered within five orders of the Euryarchaeota—constitute the last step in the trophic chain of decomposers degrading organic matter in oxygen-free environments (36). Methanogenesis is often the rate-limiting step of anaerobic digestion of organic wastes (3) due to the fast duplication times of bacteria, which generate all substrates for the slow-growing methane-producing archaea. It is also the most sensitive step in processing imbalances (4), likely due to the lack of functional redundancy among methanogens (8). High concentrations of volatile fatty acids, salts, ammonia, and heavy metals can be inhibitory for methanogens (5, 22) and are the most common reasons for reactor failure (3). Our objective was to understand the adaptation of methanogenic communities to TPOMW. We investigated methanogenic diversity and abundance in pilot digesters fed with cattle excreta and after changing their feed to TPOMW or TPOMW plus excreta. We expected that mixing both residues would allow a faster adaptation and more efficient performance of the methanogenic communities in digesting TPOMW. The cofermentation was evaluated at 37°C and 55°C. During an acclimatization period of 28 days, we screened the methanogenic diversity using an in-house-devised phylogenetic microarray, the AnaeroChip (13), and quantified dominant genera by real-time quantitative PCR (qPCR). We have taken primers from the literature, and we present four new sets of genus-specific primers and SYBR green I-optimized assays for quantifying methanogens in anaerobic environments. 相似文献
12.
Zhaoqi Wang Jinfeng Chang Shushi Peng Shilong Piao Philippe Ciais Richard Betts 《Journal of Plant Ecology》2019,12(5):804
Aims
The impacts of future global warming of 1.5°C and 2°C on the productivity and carbon (C) storage of grasslands in China are not clear yet, although grasslands in China support ~45 million agricultural populations and more than 238 million livestock populations, and are sensitive to global warming. 相似文献
13.
14.
Temperature variations in cells, tissues and organs may occur in a number of circumstances. We report here that reducing temperature of cells in culture to 25°C for 5 days followed by a rewarming to 37°C affects cell biology and induces a cellular stress response. Cell proliferation was almost arrested during mild hypothermia and not restored upon returning to 37°C. The expression of cold shock genes, CIRBP and RBM3, was increased at 25°C and returned to basal level upon rewarming while that of heat shock protein HSP70 was inversely regulated. An activation of pro-apoptotic pathways was evidenced by FACS analysis and increased Bax/Bcl2 and BclXS/L ratios. Concomitant increased expression of the autophagosome-associated protein LC3II and AKT phosphorylation suggested a simultaneous activation of autophagy and pro-survival pathways. However, a large proportion of cells were dying 24 hours after rewarming. The occurrence of DNA damage was evidenced by the increased phosphorylation of p53 and H2AX, a hallmark of DNA breaks. The latter process, as well as apoptosis, was strongly reduced by the radical oxygen species (ROS) scavenger, N-acetylcysteine, indicating a causal relationship between ROS, DNA damage and cell death during mild cold shock and rewarming. These data bring new insights into the potential deleterious effects of mild hypothermia and rewarming used in various research and therapeutical fields. 相似文献
15.
Capacity to synthesize glucose, urea, and ketone bodies is well maintained in hepatocytes after storage for at least 24 h at 4 degrees C. Substrates and albumin are the only requirements. 相似文献
16.
Metabolic activity, but not growth, has been observed in ice at temperatures from -5°C to -32°C. To improve understanding of metabolism in ice, we simultaneously examined various aspects of metabolism ((14) C-acetate utilization, macromolecule syntheses and viability via reduction of CTC) of the glacial isolates Sporosarcina sp. B5 and Chryseobacterium sp. V3519-10 during incubation in nutrient-rich ice and brine at -5°C for 50 days. Measured rates of acetate utilization and macromolecule syntheses were high in the first 20 days suggesting adjustment to the lower temperatures and higher salt concentrations of both the liquid vein network in the ice and the brine. Following this adjustment, reproductive growth of both organisms was evident in brine, and suggested for Sporosarcina sp. B5 in ice by increases in cell numbers and biomass. Chryseobacterium sp. V3519-10 cells incubated in ice remained active. These data indicate that neither low temperature nor high salt concentrations prohibit growth in ice, but some other aspect of living within ice slows growth to within the detection limits of current methodologies. These results imply that microbial growth is plausible in natural ice systems with comparable temperatures and sufficient nutrients, such as debris-rich basal ices of glaciers and ice masses. 相似文献
17.
Summary A study has been made of the efflux of radiosodium in single barnacle muscle fibers cooled to 0°C. Cooling from 24 to 0°C results in a rapid fall in the Na efflux, the magnitude of which averages 81%. Rewarming leads to almost complete restoration of the Na efflux. The Arrhenius plot shows no breaks and gives anE
a value of 14.2 kcal/mol. External application of 10–4
m-ouabain following cooling to 0°C causes a fall in the residual efflux (8%). Rewarming results in partial restoration of the Na efflux. Lowering external pH (pH
e
) results in a rise in Na efflux at 0°C, which peaks and declines rather slowly. The magnitude of the stimulatory response to acidification is a function of pH
e
over the pH
e
7.00–5.8 range, the theoretical threshold being pH
e
7.1. The magnitude of the response to acidification of cooled, ouabain-poisoned fibers suspended in Li-ASW is the same as that of fibers suspended in Na-ASW. Injection of pure protein kinase inhibitor into fibers maintained at 0°C fails to reduce the size of the response to acidification. Benzolamide but not acetazolamide, ethoxzolamide or Cl 13,580 abolishes the response to acidification. It also reverses the response to acidification. SITS is also able to abolish the response to acidification. An additional new observation is that the Na efflux at 0°C is stimulated following the injection of CaCl2 in a concentration-dependent manner. A similar response is not seen with MgCl2. Acidification (pH
e
5.8) following peak stimulation by injection of CaCl2 is without effect. These results add up to a refutation of the concept that the Na efflux at 0°C is wholly passive and that the response to acidification involves Na:Na or Na:Ca exchange. The results also weaken the argument that stimulation of the efflux by acidification is the result of activation of carbonic anhydrase. 相似文献
18.
Summary We have determined phase diagrams at 22°C for the aqueous two-phase systems composed of dextran, polyethylene glycol, and water. The effects of polyethylene glycol and dextran molecular weight on phase separation are reported. These phase diagrams provide more complete data for dextran/PEG/water system, and will be needed for the correlation of biomolecule partitioning. 相似文献
19.
Experiments were carried out to find the effect of dark-holding in distilled water at 4° C on recovery of Gamma- and UV-irradiated cells of a haploid strain ofSaccharomyces carlsbergensis. It was found that there was an appreciable increase in survival of the irradiated cells following 4 to 24 hours' holding while no increase in the number of control cells was observed following similar treatment. It is suggested that some common type of damage induced by both Gamma- and UV-radiations inS. carlsbergensis may be repaired efficiently under metabolic conditions associated with growth at 4° C in distilled water. 相似文献
20.
The long-term preservation of whole organs will almost certainly require the use of subzero temperatures and cryoprotectants. An essential part of such a technique is the ability to add a cryoprotectant in adequate concentration and subsequently to remove it without damage to the organ. In this study rabbit kidneys have been perfused with solutions containing 3% dextran and 2 m glycerol at 5 °C, and their function has been measured after removal of the glycerol. The assay technique involved the measurement of glomerular filtration rate, protein leakage, and tubular reabsorption of sodium and glucose. The results indicate that the inclusion in the perfusate of an impermeant solute (mannitol) and limitation of the rate of change of glycerol concentration (to 30 mm min?1) permits rabbit kidneys to retain a degree of function similar to that found in perfused control kidneys, although somewhat reduced in comparison with freshly isolated kidneys. 相似文献