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41.
G. Falgairette M. Bedu N. Fellmann H. Spielvogel E. Van Praagh P. Obert J. Coudert 《European journal of applied physiology and occupational physiology》1994,69(1):36-43
Field tests of running and laboratory tests were performed in La Paz [high altitude (HA), 3700 m] and in Clermont-Ferrand [low altitude (LA), 300 m] to investigate their validity at HA. Prepubertal boys of mean ages 10.6 years (HA1,n = 16; LA1,n = 28) and pubertal boys of 13.7 years (HA2,n = 12; LA2,n = 41) took part in the study. All the boys performed a 30-m sprint (v
30m), a 30-s shuttle run (v
3os) and a progressive shuttle run test until their maximal aerobic velocity (v
maxsRT). Maximal oxygen consumption was extrapolated from the last test.
. In the laboratory, the boys performed a force-velocity test (P
max), a Wingate test (P
Wing) and a graded test to measure maximal oxygen consumption
; direct method) on a cycle ergometer. At similar ages, there was no significant difference between HA and LA boys forv
30m andP
max. Thev
30s of HA boys was 3%–4% lower than those of LA boys (P<0.05); there was no significant difference forP
Wing. Significant relationships were observed at both altitudes betweenP
max (watts per kilogram) andv
30m (HA:r=0.76; LA:r=0.84) and betweenP
Wing andv
30s (HA:r=0.67; LA:r = 0.77); the slopes and the origins were the same at HA and LA. The
,v
maxSRT and
were lower by 9%, 12% and 20%, respectively, at HA than at LA (P<0.05). However, the relationships between
and
(litres per minute) at HA (r=0.88) and at LA (r=0.93) were identical. In conclusion, chronic hypoxia did not modify performance in very short dash exercises. The influence of HA appeared when the exercise duration increased and, during a maximal shuttle run test, performance was reduced by 10% at HA. Moreover, it was possible to assessP
max,P
Wing and
at HA as well as at LA from field tests. 相似文献
42.
Summary The P-43 ofEudiplodinium and homologous proteins in three other entodiniomorphid species, free-living ciliates, flagellates, and HeLa cells, were identified at the plasma membrane-cytoskeleton interface. Proteins cross-reacting with MAb B6 were also located at the ciliary inner surface of the plasma membrane. Due to the strong adhesion of the plasma membrane to the underlying cytoskeleton, classical extraction with detergents, urea, NaOH, and PTA, failed to separate the two components completely. However, the extraction properties of P-43, associated with its membrane-cytoskeleton interactive functions, suggest that this unglycosylated protein may present some analogies with proteins of the intermediate filaments. Their ubiquity and localization suggest that P-43 and MAb B6 crossreacting proteins may not be strictly epiplasmic but could be amphitropic proteins, strongly anchored to both the plasma membrane and the underlying microfilament framework, via protein-protein binding or by direct insertion in the lipid bilayer.Abbreviations BSA
bovine serum albumin
- Con A
concanavalin A
- EDTA
ethylene diamine tetraacetic acid
- EM
electron microscopy
- IF
intermediate filaments
- MAb
monoclonal antibody
- MET
2-mercaptoethanol
- MW
molecular weight
- PAb
polyclonal antibody
- PBS
phosphate buffered saline
- PMSF
phenylmethylsulfonyl fluoride
- PTA
phosphotungstic acid
- SDS
sodiumdodecyl sulfate
- TAME
Na-p-tosyl-arginine methyl ester
- TLCK
Na-p-tosyl-lysine chloromethyl ketone 相似文献
43.
Some rumen ciliates have endosymbiotic methanogens 总被引:16,自引:0,他引:16
Bland J. Finlay Genoveva Esteban Ken J. Clarke Alan G. Williams T.Martin Embley Robert P. Hirt 《FEMS microbiology letters》1994,117(2):157-161
Abstract Most of the small ciliate protozoa, including Dasytricha ruminantium and Entodinium spp. living in the rumen of sheep, were found to have intracellular bacteria. These bacteria were not present in digestive vacuoles. They showed characteristic coenzyme F420 autofluorescence and they were detected with a rhodamine-labelled Archaea-specific oligonucleotide probe. The measured volume percent of autofluorescing bacteria (1%) was close to the total volume of intracellular bacteria estimated from TEM stereology. Thus it is likely that all of the bacteria living in the cytoplasm of these ciliates were endosymbiotic methanogens, using H2 evolved by the host ciliate to form methane. Intracellular methanogens appear to be much more numerous than those attached to the external cell surface of ciliates. 相似文献
44.
Abstract Incorporation of [ methyl -3 H]thymidine into bacterial DNA was determined for a range of axenic anaerobic bacterial cultures: fermentative heterotrophs, sulphate-reducing bacteria, purple sulphur bacteria, acetogens and methanogens. Anaerobically growing Bacillus sp. and the obligate aerobe Thiobacillus ferrooxidans were also investigated. Actively growing cultures of sulphate-reducing bacteria belonging to the genera Desulfovibrio, Desulfotomaculum, Desulfobacter, Desulfobotulus and Desulfobulbus , purple sulphur bacteria ( Chromatium vinosum OP2 and Thiocapsa roseopersicina OP1), methanogens ( Methanococcus GS16 and Methanosarcina barkeri ) and an acetogen ( Acetobacterium woodii ) did not incorporate [ methyl -3 H]thymidine into DNA. The only obligate anaerobes in which thymidine incorporation into DNA could be unequivocally demonstrated were members of the genus Clostridium . Anaerobically growing Bacillus sp. also incorporated thymidine. These data demonstrate that pure culture representatives of major groups of anaerobic bacteria involved in the terminal oxidation of organic carbon and anoxygenic phototrophs within sediments are unable to incorporate [ methyl -3 H]thymidine into DNA, although some obligate and facultative anaerobes can. Variability in thymidine incorporation amongst pure culture isolates indicates that unless existing techniques can be calibrated to take this into consideration then productivity estimates in both aerobic and anaerobic environments may be greatly underestimated using the [ methyl -3 H]thymidine technique. 相似文献
45.
SLAVA S. EPSTEIN 《The Journal of eukaryotic microbiology》1994,41(5):500-503
ABSTRACT A new species of marine interstitial ciliate, Tracheloraphis primitarum sp. n., is described from intertidal sands (160-200-μm medium grain size) along the Northwest Atlantic coast. Living specimens are not transparent under incident light, 0.4-0.9 mm in length, and are characterized by an elongated body, bulbous anterior and rounded posterior regions. Cytostome is simple without a cleft on the lip. Protargol silver impregnation shows 18-29 longitudinal kineties. The glabrous zone is very narrow, 6-7 μm wide, and corresponds to the area occupied by one kinety and two interkinetal spaces. Ten to fifteen kineties terminate against the glabrous zone. Interkinetal extrusomes are present. The nuclear apparatus is a single centrally-placed nuclear group that consists of three large irregular macronuclei and 2-3 micronuclei; these are either clustered or encapsulated. 相似文献
46.
Because of its low solubility it is unlikely that elemental sulfur serves as the direct substrate for sulfur-reducing bacteria. To test the hypothesis that polysulfide may represent a soluble intermediate of sulfur reduction, the maximal polysulfide concentrations formed from elemental sulfur in aqueous sulfide solutions were measured at near neutral pH and at temperatures up to 90°C. The saturation concentrations decreased by two orders of magnitude when the pH was lowered from 7 to 6 at a given temperature, and increased about tenfold when the temperature was raised from 37°C to 90°C at a given pH. The dissolution of 0.1 mM zerovalent sulfur in 1 mM sulfide (H2S+HS–) required a pH of 7.5 at 20°C and of only 6.1 at 100°C. A comparison with the growth optima of sulfur-reducers suggests that polysulfide is present at sufficient concentration at the growth conditions of the Bacteria and the moderately acidophilic Archaea. Polysulfide is apparently not available at the growth conditions of the extremely acidophilic Archaea. Alternative mechanisms for the sulfur utilization under these conditions are discussed.Abbreviations MOPS
Morpholinopropanesulfonate
- PIPES
1,4 piperazine-N,N-bis(2-ethanesulfonate)
- HEPES
N-2-hydroxy-ethylpiperazine-N-ethanesulfonate 相似文献
47.
The methyl chloride metabolism of the homoacetogenic, methyl chloride-utilizing strain MC was investigated with cell extracts and cell suspensions of the organism. Cell extracts were found to contain all enzyme activities required for the conversion of methyl chloride or of H2 plus CO2 to acetate. They catalyzed the dechlorination of methyl chloride with tetrahydrofolate as the methyl acceptor at a rate of 20 nmol/min × mg of cell protein. Also, the O-demethylation of vanillate with tetrahydrofolate could be measured at a rate of 40 nmol/min × mg. Different enzyme systems appeared to be responsible for the dehalogenation of CH3Cl and for the O-demethylation of methoxylated aromatic compounds, since cells grown with methoxylated aromatic compounds exhibited a significantly lower activity of CH3Cl conversion than methyl chloride grown cells and vice versa. In addition, ammonium thiocyanate (5 mM) completely inhibited CH3Cl dechlorination, whereas the consumption of vanillate was not affected significantly. The data were taken to indicate, that the methyl chloride dehalogenation is catalyzed by a specific, inducible enzyme present in strain MC, and that tetrahydrofolate rather than the corrinoid-protein involved in acetate formation is the primary acceptor of the methyl group in the dechlorination reaction. 相似文献
48.
Marc J. E. C. van der Maarel Peter Quist Lubbert Dijkhuizen Theo A. Hansen 《Archives of microbiology》1993,160(5):411-412
Dimethylsulfoniopropionate, an osmolyte of marine algae, is thought to be the major precursor of dimethyl sulfide, which plays a dominant role in biogenic sulfur emission. The marine sulfate-reducing bacterium Desulfobacterium strain PM4 was found to degrade dimethylsulfoniopropionate to 3-S-methylmercaptopropionate. The oxidation of one of the methyl groups of dimethylsulfoniopropionate was coupled to the reduction of sulfate; this process is similar to the degradation betaine to dimethylglycine which was described earlier for the same strain. Desulfobacterium PM4 is the first example of an anaerobic marine bacterium that is able to demethylate dimethylsulfoniopropionate.Abbreviations DMSP
dimethylsulfoniopropionate
- DMS
dimethyl sulfide
- MMPA
3-S-methylmercaptopropionate 相似文献
49.
Thauera selenatis was grown anaerobically in minimal medium with either selenate or nitrate as the terminal electron acceptor and acetate as the carbon source and electron donor. The molar cell protein yields, YM-protein (selenate) and YM-protein (nitrate), were found to be 7.8 g cell protein/mol selenite formed and 7.5 g cell protein/mol nitrite formed, respectively. These values represent YM values of 57 and 55 g (dry weight)/mol acetate when selenate or nitrate was the electron acceptor, respectively. Based upon a calculated YATP value of 10.0 g (dry weight) cells/mol ATP, for growth on acetate in inorganic salts, growth with selenate as the terminal electron acceptor theoretically yielded 5.7 ATP/acetate oxidized, and 5.5 ATP when nitrate was the terminal electron acceptor. The results support the conclusion that energy is conserved via electron transport phosphorylation when selenate or nitrate reduction are the terminal electron acceptors during anaerobic growth with acetate. 相似文献
50.
Ken-ichiro Takamiya Yuzo Shioi Masakazu Morita Hiroyuki Arata Minoru Shimizu Michio Doi 《Archives of microbiology》1993,159(1):51-56
Characteristics and occurrence of cytochrome c-552 from an aerobic photosynthetic bacterium, Roseobacter denitrificans, were described.Relative molecular mass of the cytrochrome was 13.5 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and 15,000 by gel filtration. This cytochrome was a acidic protein having a pI of 5.6 and Em was +215 mV at pH 7.0. Absorption peaks were at 278, 408 and 524 nm in the oxidized form and 416, 523 and 552 nm in the reduced form.Amino acid composition and N-terminal amino acid sequence of cytochrome c-552 determined for 24 residues had low similarities to those of cytochrome c-551 of this bacterium, which is homologous to cytochrome c
2, although the physico-chemical properties of these two cytochromes were similar to each other.Cytochrome c-552 was maximally synthesized in the light under aerobic conditions but not in the dark. The synthesis also occurred in the presence of alternative acceptors such as trimethylamine N-oxide (TMAO) and nitrate under anaerobic conditions. Our results suggest that cytochrome c-552 is involved in TMAO respiration and denitrification in R. denitrificans, although the effect of light remains to be solved.Abbreviations Em
Midpoint redox potential
- PAGE
Polyacrylamide ge electrophoresis
- SDS-PAGE
Sodium dodecyl sulfate polyacrylamide gel electrophoresis
- TMAO
Trimethylamine N-oxide 相似文献