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31.
Two spirochete strains isolated earlier from Thiodendron bacterial sulfur mats grew better under microaerobic (0.3–0.5 mg O2/l) than under anaerobic conditions. The microaerobic growth of these strains was accompanied by a twofold increase in the cell yield and the efficiency of glucose utilization, despite the fact that an additional amount of ATP (and, hence, glucose) was spent in this case for the synthesis of exopolysaccharides. Glucose metabolism under microaerobic conditions gave rise to more oxidized products (acetate and carbon dioxide) than under anaerobic conditions (formate, ethanol, pyruvate, and hydrogen). The paper considers two putative mechanisms implemented by aerotolerant spirochetes: adaptive (the use of a more efficient pathway of glucose catabolism) and protective (an enhanced synthesis of exopolysaccharides and the reduction of hydrogen peroxide by the reduced sulfur compounds thiosulfate and sulfide, yielding elemental sulfur). The formation of Thiodendron bacterial sulfur mats in saltwater environments is also discussed.Translated from Mikrobiologiya, Vol. 73, No. 6, 2004, pp. 725–733.Original Russian Text Copyright © 2004 by Dubinina, Grabovich, Chernyshova. 相似文献
32.
Onishchenko GG Lomov IuM Mishan'kin BN Mazrukho BL Podosinnikova LS Kudriakova TA Moskvitina EA Vodop'ianov SO Ryzhko IV Kazakova ES Sharova IN Plotnikova EA Davydova NA Abramova EG Korolev IuS Shestialtynova IS Sharifulina DM Kuriaeva NIu Iumangulova EF Chernyshova AV Bugorkova TV Rusakova TG Maslenikova AL Milova MV Zakharova LI Bilalova TG Shut'ko AG Kachkina GV 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2002,(2):3-6
Information on V. cholerae eltor isolated in the focus of cholera in Kazan in 2001 at different periods of the outbreak is presented. The identity of strains isolated from patients, vibriocarriers and environmental objects, including their antibioticograms (sensitivity to cyprofloxacin and resistance to trimethoprim--sulfamethoxazole, streptomycin, furazolidone and nalidixic acid, which may be regarded as markers), is shown. Variable tandem repetitions in the DNA of 30 isolates strains of different origin have been determined. The results of this determination make it possible to classify all these strains as one genotype, which confirms the suggestion on the circulation of one subclone of the infective agent of cholera in the focus. As revealed in this investigation, the isolated strains are labile with respect to diagnostic phage eltor, while ctx+ strains are resistant to phage eltor ctx+. 相似文献
33.
The dynamics of chromosome aberrations in human lymphocyte culture cells of the 1-st division after exposure in the G0 phase for 1h to functionally different alkylating mutagens - ethyleneimine derivatives (bifunctional phosphamide, threefunctional thiophosphamide, tetrafunctional dipine and pentafunctional photrin) was analysed. The frequency of chromosome aberrations was constant after exposure to "dicentric" mutagens (dipine, photrin) at all times of fixation, while under the action of "monocentric" mutagens (phosphamide, thiophosphamide) this declined significantly with increasing the duration of cultivation. The portion of aberrations of the chromatid remains unaltered in time, in case of both "dicentric" and "monocentric" mutagens, reaching 75% for "monocentric" and 50% for "dicentric" of the total number of chromosome aberrations. 相似文献
34.
An anchored restriction-mapping approach applied to the genetic analysis of the Anopheles gambiae malaria vector complex 1 总被引:1,自引:0,他引:1
We introduce here a simple approach for rapidly determining restriction
maps for a number of regions of a genome; this involves "anchoring" a map
with a rare restriction site (in this case the seldom-cutting EagI)
followed by partial digestion of a frequent-cutting enzyme (e.g., Sau 3A).
We applied this technology to five species of the Anopheles gambiae
complex. In a single Southern blot we obtained about a 15-kb restriction
map each for the mtDNA, rRNA gene, and a scnDNA region for each of five
species. Phylogenetic analyses of these regions yield trees at odds with
the more traditional chromosome inversion-based trees. The value of the
approach for systematic purposes is the ease with which several large,
independent regions of the genome can be quickly assayed for molecular
variation.
相似文献
35.
Theoretical considerations have shown that the five possible overlapping
reading-frame configurations differ significantly in their coding
flexibility and thus in their information content (Siegel and Fitch 1980;
Smith and Waterman 1980). Contrary to expectation, the overlapping frame
configuration allowing the greatest coding flexibility is rarely seen,
whereas one of the most constraining is common. We point out here that this
overlapping reading-frame paradox and an observed but unexplained
preference in coding regions for a pyrimidine-purine at codon boundaries
(Shepherd 1981; Jones and Kafatos 1982; Smith et al. 1983) are intimately
linked. The codon boundary preference, which may be related to translation
efficiency or accuracy, places constraints on the evolution of overlapping
coding regions. These considerations may help identify actual coding
regions in DNA sequences. We have analyzed five sequenced (enteric)
bacterial insertion sequences for codon boundary incidences and
reading-frame configurations and find that they are consistent with these
proposed constraints.
相似文献
36.
Yelena V. Lyubun Andreas Fritzsche Marina P. Chernyshova E. Gert Dudel Evgenii E. Fedorov 《Plant and Soil》2006,286(1-2):219-227
The transformation of sodium arsenite and sodium arsenate by the rhizospheric nitrogen-fixing bacterium Azospirillum brasilense Sp245 in association with wheat (Triticum aestivum L. ‘Saratovskaya 29’) was studied. The effect produced by the A. brasilense strain on the morphological parameters of wheat in an As-polluted environment was examined. The plants were cultivated in a hydroponic system, with glass beads serving as a support for root growth. The plant-growth medium (an artificial soil solution) was deficient in P and Fe. The total initial As concentrations used were 75, 750, and 7500 μg l−1. The As compounds used contained sodium arsenate and sodium arsenite at an As(V):As(III) ratio of 1:3.6 (in terms of As) in all experiments. Inoculation of A. brasilense Sp245 led to a decrease in the overall root length and to the formation of lateral roots; both effects are possibly related to the bacteria’s ability to synthesize auxins. Inoculation also changed the As(V): As(III) ratio of the plant-growth medium. In all experiments, the concentration of As(V) in the nutrient medium increased relative to the initial one and was approximately 1.5-fold higher than that in the medium of uninoculated plants. This value slightly decreased (1.6 > 1.5 > 1.4) with increasing concentration of As in the medium. Azospirillum-inoculated plants accumulated less As than did the surface-sterilized uninoculated plants. This study shows that A. brasilense Sp245 in association with wheat changes the speciation, bioavailability, and plant uptake of As. 相似文献
37.
Removal of the mast cells from the mouse abdominal cavity by repeated washings as well as their osmotic destruction with distilled water are suitable methods to study regeneration of mast cells in postnatal ontogenesis. Simultaneous application of their differential staining with alcian blue-safranin makes it possible to reveal successive stages of the newly formed mast cells maturation and determine duration of every stage. The time of complete renovation of the peritoneal mast cells has been stated to be, according to the mode of the stimulation, 60--80 days. Total duration of the first two stages of maturation is 1--2 days. Mast cell differentiation is fully completed by the 11th day. 相似文献
38.
Evolutionary relatedness of some primate models of Plasmodium 总被引:1,自引:0,他引:1
Primate--and, specifically, monkey--malaria infections are commonly used
for understanding the pathology of and immune response to the human disease
because they are thought to resemble most closely the host-parasite
relationship found in humans. Plasmodium cynomolgi is used extensively as a
model for the human parasite, P. vivax, and P. knowlesi is used primarily
as a model for the development of erythrocytic-stage vaccines. Both of
these simian parasites can naturally infect man, resulting in mildly
symptomatic episodes of the disease. The phylogenetic relationship between
these two simian parasites and previously characterized Plasmodium species,
including P. vivax, was examined by comparison of the asexually expressed
small- subunit ribosomal RNA genes. Our analysis confirmed that P. vivax is
most closely related to P. cynomolgi and that it remains an appropriate
model of the human pathogen. Furthermore, with P. knowlesi and P. fragile,
these two species form a group of closely related species, distant from
other Plasmodium species. What is considered to be the most ancient of the
human malaria pathogens, P. malariae, was also included in the analysis and
does not group at all with other simian or human parasites.
相似文献
39.
Chernyshova MP Alen'kina SA Nikitina VE Ignatov VV 《Prikladnaia biokhimiia i mikrobiologiia》2005,41(4):444-448
It was found that Azospirillum brasilensis strain Sp7 is able to produce extracellular proteolytic enzymes. The enzymes were active within a broad range of pH values, with two peaks of activity being located in the acid and alkaline pH areas; required calcium ions; and exhibited substrate specificity with respect to azogelatin. Zymography allowed at least four proteolytic enzymes with molecular weights of 32, 45, 52, and 174 kDa to be detected in A. brasilense Sp7 culture liquid. It was shown that the lectin from A. brasilense Sp7 can inhibit proteolytic enzymes. 相似文献
40.
The culture liquids of three Xanthomonas campestris pv. campestris strains were found to possess proteolytic activity. The culture liquid of strain B-611 with the highest proteolytic activity was fractionated by salting-out with ammonium sulfate, gel filtration, and ion-exchange chromatography. The electrophoretic analysis of active fractions showed the presence of two proteases in the culture liquid of strain B-611, the major of which being serine protease. The treatment of cabbage seedlings with the proteases augmented the activity of peroxidase in the cabbage roots by 28%. 相似文献