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Thermal sensitivity of mitochondrial function in the Antarctic Notothenioid Lepidonotothen nudifrons 总被引:4,自引:0,他引:4
I. Hardewig H. O. Pörtner L. S. Peck 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(8):597-604
The thermal sensitivity of mitochondrial function was investigated in the stenothermal Antarctic fish Lepidonotothen nudifrons. State 3 respiration increases with increasing temperature between 0 °C and 18 °C with a Q
10 of 2.43–2.63. State 4 respiration in the presence of oligomycin, an inhibitor of mitochondrial ATP synthase, quantifies the
leakage of protons through the inner mitochondrial membrane, which causes oxygen consumption without concomitant ATP production.
This parameter shows an unusually high Q
10 of 4.21 ± 0.42 (0–18 °C), which indicates that proton leakage does not depend merely on ion diffusion but is an enzyme-catalysed
process. The differential thermal sensitivity of oxidative phosphorylation (=state 3) and proton leakage (=state 4 in the
presence of oligomycin) leads to progressive uncoupling of the mitochondria and decreased efficiency of oxidative phosphorylation
under in vivo conditions if the body temperature of L. nudifrons increases.
Accepted: 2 September 1999 相似文献
125.
J. R. Peck J. Yearsley G. Barreau 《Proceedings. Biological sciences / The Royal Society》1999,266(1431):1857
We present the results of a computer simulation model in which a sexual population produces an asexual mutant. We estimate the probability that the new asexual lineage will go extinct. We find that whenever the asexual lineage does not go extinct the sexual population is out-competed, and only asexual individuals remain after a sufficiently long period of time has elapsed. We call this type of outcome an asexual takeover. Our results suggest that, given repeated mutations to asexuality, asexual takeover is likely in an unstructured environment. However, if the environment is subdivided into demes that are connected by migration, then asexual takeover becomes less likely. The probability of asexual takeover declines towards zero as the number of demes increases and as the rate of migration decreases. The reason for this is that asexuality leads to a greater loss of fitness due to mutation and genetic drift, in comparison to what occurs under sexual reproduction. Population subdivision slows the spread of asexual lineages, which allows more time for the genetic degeneration caused by asexuality to take place. 相似文献
126.
Growth from Spores of Nonproteolytic Clostridium botulinum in Heat-Treated Vegetable Juice 总被引:1,自引:0,他引:1 下载免费PDF全文
Unheated spores of nonproteolytic Clostridium botulinum were able to lead to growth in sterile deoxygenated turnip, spring green, helda bean, broccoli, or potato juice, although the probability of growth was low and the time to growth was longer than the time to growth in culture media. With all five vegetable juices tested, the probability of growth increased when spores were inoculated into the juice and then heated for 2 min in a water bath at 80°C. The probability of growth was greater in bean or broccoli juice than in culture media following 10 min of heat treatment in these media. Growth was prevented by heat treatment of spores in vegetable juices or culture media at 80°C for 100 min. We show for the first time that adding heat-treated vegetable juice to culture media can increase the number of heat-damaged spores of C. botulinum that can lead to colony formation. 相似文献
127.
Jurre Y. Siegers Vijaykrishna Dhanasekaran Ruopeng Xie Yi-Mo Deng Sarika Patel Vanra Ieng Jean Moselen Heidi Peck Ammar Aziz Borann Sarr Savuth Chin Seng Heng Asheena Khalakdina Michael Kinzer Darapheak Chau Philomena Raftery Veasna Duong Ly Sovann Ian G. Barr Erik A. Karlsson 《Journal of virology》2021,95(24)
128.
Frederick L. Moffat Tieran Han Zhi-Ming Li Michael D. Peck Wenche Jy Yeon S. Ahn Arthur J. Chu Lilly Y. W. Bourguignon 《Journal of cellular physiology》1996,168(1):26-33
That L-arginine (L-Arg) augments the host response to acute bacterial sepsis suggests that this amino acid intervenes early in the immune response, perhaps via the nitric oxide synthetase (NOS) pathway. The effect of L-Arg supplementation on in vitro phagocytosis of fluorescein-labeled, heat-killed Staphylococcus aureus by peripheral blood neutrophils (PMNs) from 12 normal human volunteers was studied. Separated PMNs were incubated for 2 h with labeled bacteria, with and without supplemental L-Arg, D-arginine, glycine, and/or the NOS inhibitors L-canavanine, aminoguanidine, or L-NG-nitroarginine methyl ester. PMNs were fixed and extracellular fluorescence quenched with crystal violet. By flow cytometry and confocal microscopy, L-Arg supplementation was shown to result in a highly significant increase in PMN bacterial phagocytosis, the maximal effect being seen with L-Arg 380 μM and falling off with higher concentrations. This augmentation was completely abrogated by NOS inhibitors in molar excess, but inhibitors alone did not suppress phagocytosis below that of unsupplemented controls. Neither D-arginine nor glycine affected phagocytosis; the L-Arg effect was stereospecific and not related to utilization of L-Arg as an energy source. L-Arg supplementation significantly enhances bacterial phagocytosis in human neutrophils, perhaps by effects on cytoskeletal phenomena, and this appears to be mediated through NOS activity. Phagocytosis by nonspecific immune cells which intervene early in the response to sepsis is critically important, and beneficial effects of L-Arg on the clinical course of sepsis may be due at least in part to augmentation of phagocyte function. © 1996 Wiley-Liss, Inc. 相似文献
129.
The escape swimming performance of the Antarctic scallop, Adamussium colbecki, was measured in animals acclimated for 6 weeks to –1, 0 or 2°C and tested at –1.5 to +1.5°C. Clap duration and swimming velocity were significantly related to temperature, but were not affected by acclimation, demonstrating no phenotypic plasticity. Comparisons of the mean swimming velocity of A. colbecki with the published data for temperate and tropical species showed little evidence for evolutionary compensation for temperature, with all data fitting to a single exponential relationship with a Q10 of 2.08 (0–20°C). The contraction kinetics of the isolated fast adductor muscle of A. colbecki were determined and the times to 50% peak tension and 50% relaxation had Q10s (0–4°C) of 3.6 and 4.7, respectively. The Q10 of the overall relationship for pooled time to peak twitch data for four scallop species was 2.05 (0–20°C). Field studies revealed low mobility and poor escape performance in wild A. colbecki. A combination of thermodynamic constraints, reduced food supply, and lower selective pressure probably explains the low levels of swimming performance seen in A. colbecki. 相似文献
130.
The success of any organism depends not only on niche adaptation but also the ability to survive environmental perturbation
from homeostasis, a situation generically described as stress. Although species-specific mechanisms to combat “stress” have
been described, the production of heat shock proteins (HSPs), such as HSP70, is universally described across all taxa. Members
of the HSP70 gene family comprising the constitutive (HSC70) and inducible (HSP70) members, plus GRP78 (glucose-regulated
protein, 78 kDa), a related HSP70 family member, were cloned using degenerate polymerase chain reaction (PCR) from two evolutionary
divergent Antarctic marine molluscs (Laternula elliptica and Nacella concinna), a bivalve and a gastropod, respectively. The expression of the HSP70 family members was surveyed via quantitative PCR after
an acute 2-h heat shock experiment. Both species demonstrated significant up-regulation of HSP70 gene expression in response
to increased temperatures. However, the temperature level at which these responses were induced varied with the species (+6–8°C
for L. elliptica and +8–10°C for N. concinna) compared to their natural environmental temperature). L. elliptica also showed tissue-specific expression of the genes under study. Previous work on Antarctic fish has shown that they lack
the classical heat shock response, with the inducible form of HSP70 being permanently expressed with an expression not further
induced under higher temperature regimes. This study shows that this is not the case for other Antarctic animals, with the
two molluscs showing an inducible heat shock response, at a level probably set during their temperate evolutionary past. 相似文献