“Oxygen regulation” of the respiratory chain composition in the yeast Debaryomyces hansenii under multiple stress

It was shown that two stress factors, hypoxia and hyperosmotic shock, if applied simultaneously to the yeast Debaryomyces hansenii, display an antagonistic mode of interaction, which results in an increased degree of halophily of this microorganism under microaerobic conditions. Studies of the effects of respiration inhibitors (sodium azide and salicyl hydroxamic acid, SHA) and of the pattern of changes in the composition of the respiratory chain of Debaryomyces hansenii under the stated stress conditions led to the suggestion of three (or four) chains of electron transfer functioning simultaneously in the cell: the classical respiratory chain involving cytochrome-c oxidase, an alternative respiratory chain involving a cyanide-and azide-resistant oxidase, and additional respiratory chains involving oxidases resistant to salt, azide and SHA. Thus, the antagonistic mode of interaction between hypoxia and hyperosmotic shock results from the redirection of the electron flow from the salt-susceptible respiratory systems to the salt-unsusceptible ones encoded by “the hypoxia genes” and activated (induced) under microaerobic conditions.     

Osmoadaptation Strategy of the Most Halophilic Fungus,Wallemia ichthyophaga,Growing Optimally at Salinities above 15% NaCl

Wallemia ichthyophaga is a fungus from the ancient basidiomycetous genus Wallemia (Wallemiales, Wallemiomycetes) that grows only at salinities between 10% (wt/vol) NaCl and saturated NaCl solution. This obligate halophily is unique among fungi. The main goal of this study was to determine the optimal salinity range for growth of the halophilic W. ichthyophaga and to unravel its osmoadaptation strategy. Our results showed that growth on solid growth media was extremely slow and resulted in small colonies. On the other hand, in the liquid batch cultures, the specific growth rates of W. ichthyophaga were higher, and the biomass production increased with increasing salinities. The optimum salinity range for growth of W. ichthyophaga was between 15 and 20% (wt/vol) NaCl. At 10% NaCl, the biomass production and the growth rate were by far the lowest among all tested salinities. Furthermore, the cell wall content in the dry biomass was extremely high at salinities above 10%. Our results also showed that glycerol was the major osmotically regulated solute, since its accumulation increased with salinity and was diminished by hypo-osmotic shock. Besides glycerol, smaller amounts of arabitol and trace amounts of mannitol were also detected. In addition, W. ichthyophaga maintained relatively small intracellular amounts of potassium and sodium at constant salinities, but during hyperosmotic shock, the amounts of both cations increased significantly. Given our results and the recent availability of the genome sequence, W. ichthyophaga should become well established as a novel model organism for studies of halophily in eukaryotes.     

Chemolithotrophic sulfur bacteria in sediments,mats, and stromatolites of western Australian saline lakes

Samples of stromatolites, microbial mats, and sediments from four saline lakes (approximate seasonal salinity ranges 20–220%o) in Western Australia were used to establish enrichments for elective cultures of aerobic and anaerobic denitrifying chemolithoautotrophs that could grow with thiosulfate as sole energy source. Organisms of these types were obtained from all sources tested. Twenty‐four pure cultures were isolated, all of which were gram‐negative, rod‐shaped bacteria exhibiting a considerable diversity of metabolic capability. Isolation of these obligate and facultative sulfur‐oxidizing chemolithotrophs from the stromatolite and mat habitats indicates the possibility that these rod‐shaped bacteria contribute to the oxidative phase of the sulfur cycle in these habitats, in addition to oxidation by phototrophs or Beggiatoa. Only four of the pure cultures could grow without salt, but all 24 showed significant halophily, some tolerating 3 M NaCl. Three novel isolates of NaCl‐dependent, thiosulfate‐oxidizing, aerobic and denitrifying obligate chemolithotrophs are described. In addition, a facultatively heterotrophic halophilic strain growing either methylotrophically on methylamine or chemolithotrophically on thiosulfate aerobically or with anaerobic denitrification was found.     

"Oxygen regulation" of the respiratory chain composition in the yeast Debaryomyces hansenii under multiple stress

It was shown that two stress factors, hypoxia and hyperosmotic shock, if applied simultaneously to the yeast Debaryomyces hansenii, display an antagonistic mode of interaction, which results in an increased degree of halophily of this microorganism under microaerobic conditions. Studies of the effects of respiration inhibitors (sodium azide and salicyl hydroxamic acid, SHA) and of the pattern of changes in the composition of the respiratory chain of Debaryomyces hansenii under the stated stress conditions led to the suggestion of three (or four) chains of electron transfer functioning simultaneously in the cell: the classical respiratory chain involving cytochrome-c oxidase, an alternative respiratory chain involving a cyanide- and azide-resistant oxidase, and additional respiratory chains involving oxidases resistant to salt, azide and SHA. Thus, the antagonistic mode of interaction between hypoxia and hyperosmotic shock results from the redirection of the electron flow from the salt-susceptible respiratory systems to the salt-unsusceptible ones encoded by "the hypoxia genes" and activated (induced) under microaerobic conditions.     

Relationships between the osmoadaptation strategy, amino acid composition of bulk protein, and properties of certain enzymes of haloalkaliphilic bacteria

Haloalkaliphilic microorganisms isolated from soda lakes were compared in terms of the amino acid composition of bulk protein and the reaction of a number of key enzymes to salts and pH of the medium. In the extremely haloalkaliphilic bacterium Natroniella acetigena (selt-in osmoadaptation strategy), acidic amino acids (glutamic and aspartic) made up 30.91 mol % of the total of bulk protein amino acids. In the moderate haloalkaliphiles Tindallia magadiensis, Halomonas campisalis, and Halomonas sp. AIR-2 (compatible-solutes osmoadaptation strategy), the proportion of acidic amino acids (24.36, 23.15, and 23.58 mol %, respectively) was lower than in N. acetigena but higher than in the freshwater Acetobacterium paludosum (20.77 mol %). The excess of acidic amino acids over basic amino acids (lysine and arginine) increased with the degree of halophily. The enzymes of haloalkaliphiles proved to be tolerant to salts and high pH values, although the degree of tolerance varied. The activity of N. acetigena CO dehydrogenase was maximum in the presence of 0.7 M NaCl, but it was virtually independent of the NaHCO₃ concentration. The hydrogenase and CO dehydrogenase of T. magadiensis exhibited maximum activity in the absence of NaCl; the Co dehydrogenase was most active at 0.25 M NaHCO₃, and hydrogenase activity was only weakly dependent on NaHCO₃ in the concentration range of 0–1.2 M. The nitrate reductases of H. campisalis and Halomonas sp. AIR-2 were active in broad ranges of NaCl and KCl concentrations; the activity maxima were recorded at moderate concentrations of these salts. The pH optima of most of the studied enzymes of haloalkaliphiles were in the alkaline zone. Thus, it was shown that the amino acid composition of bulk protein is determined by the osmoadaptation strategy employed by the bacterium. A correlation was found between the salt tolerance of enzymes and the proportion of acidic amino acids in the bulk protein. The ability of enzymes to function at high pH values is one of the mechanisms of adaptation of microorganisms to high pH values.     

Evaluation of tomato wild species for resistance to race T1 nad T3 of Xanthomonas vesicatoria

Thirty six tomato wild species accessions of the subgenera Eulycopersicon and Eriopersicon of the genus Lycopersicon were inoculated with race T1 and T3 of Xanthomonas vesicatoria by vaccum infiltration method. Degree of diseases was evaluated by scale of 0 to 4. It was established that some accessions showed low degree of disease to race T1 and others to race T3. LA 2623 indicated very low degree of disease to race T1 and was immune in inoculation with T3. LA 386 and LA 1297 manifested hypersensitive reaction to both races and PI 127826 to race T3 only. The accessions possessing low degree of disease or hypersensitive reaction to race T1 and race T3 are new promising sources of resistance to Xanthomonas vesicatoria.     

Outlines for the definition of halotolerance/halophily in yeasts: Candida versatilis (halophila) CBS4019 as the archetype?

Candida versatilis (halophila) CBS4019 was chosen to study the physiological reactions of long-term exposure to extremely high salt concentrations. In general, our results show a significant increase in enzyme expression during growth under stress conditions. Although glycerol and mannitol pathways are not under glucose repression, they were found to be metabolically regulated. Glycerol-3P-dehydrogenase used either of its cofactors NADPH or NADH, being in favor of NADPH during growth with high salt concentrations. This ability of interchanging cofactors, an increased fermentation rate, and the observed mannitol pathway activity are suggested to contribute to the yeasts' redox stability. Enzymes per se were not salt-tolerant in vitro. Consistently, intracellular sodium was low and intracellular potassium, a requirement for growth, was high. The concept of halophily and its applicability to yeasts is discussed.     

Isomerization ofn- andi-butyrate in anaerobic methanogenic systems

Studies of the degradation of the two isomeric forms of butyrate in different anaerobic environments showed isomerization betweenn- andi-butyrate. Degradation rates were similar for the different examined systems and degradation rates forn-butyrate degradation were generally higher than fori-butyrate. Degradation rates forn-butyrate ranged from 0.52 to 1.39 day^–1, while the rates fori-butyrate were from 0.46 to 1.15 day^–1. Production of isomers was not observed when the volatile fatty acid degradation was inhibited by addition of bromoethane sulfonic acid, indicating that isomerization was coupled to the methanogenic degradation of the acid. The degree of isomerization observed duringn-butyrate degradation was similar to the degree duringi-butyrate degradation. Experiments indicated that the isomerization degree was higher for the thermophilic than for the mesophilic inocula.     

The Effect of the Genotype on the Expressiveness of Character vestigial and Polyteny of Giant Chromosomes in Drosophila melanogaster Meig.

The effects of the Bar (B) andwhite (w) mutations on the expressiveness of the character vestigial (vg) and the degree of polyteny of salivary gland giant chromosomes were studied in Drosophila melanogaster.Either mutation changed both the expressiveness of vestigial and the degree of chromosome polyteny. A negative association between the vg expressiveness and the degree of chromosome polyteny was revealed and proved to be stronger in females than in males. The parameters under study were shown to differ between females and males.     

Effect of Moniliformis moniliformis density on distribution within the definitive host population (Rattus norvegicus)

The population dynamics of Moniliformis moniliformis was studied in ‘free-ranging’ laboratory rats, Rattus norvegicus, presented with different relative density levels of M. moniliformis in cockroaches, Periplaneta americana. Changes in selected population parameters of the negative binomial distribution were evaluated as indicators of changes in aggregation. A significant increase in the degree of aggregation of parasites occurred as a result of the increase in relative density of infective stages available to the rats. This increase in aggregation was due to the increase in over-dispersion that occurred in female rats only. The degree of aggregation in females was found to be significantly higher than that in males at both treatment levels. The best indicators of the degree of aggregation were found to be the ratio of the variance to the relative density and the ratio of the log-variance to log-relative density. Changes in k were not correlated with changes in over-dispersion or the relative density.     

Symbiotic Chlorella enhances the thermal tolerance in Paramecium bursaria

Symbiotic Chlorella enhanced the tolerance to high temperature in Paramecium bursaria. We found that 50% of Chlorella-free P. bursaria died within 85 s of exposure to 41°C in a standard saline solution, while the presence of Chlorella almost doubled the survival time of P. bursaria (160 s, P<0.001). The degree of tolerance in 3-(3,4-dichlorophenyl)-1,1-dimethylurea (an inhibitor for photosynthesis) treated Chlorella-containing P. bursaria and Chlorella-containing organisms kept in the dark for 24 h was as low as in Chlorella-free organisms. The degree of tolerance to high temperature in Chlorella-free P. bursaria in solutions containing maltose, glucose, fructose or O₂, was as high as that of normal Chlorella-containing organisms. The degree of thermal tolerance in Chlorella-containing P. bursaria was not affected in the presence of these carbohydrates or oxygen.     

Variability in epidermal characters of <Emphasis Type="Italic">Ginkgo tzagajanica</Emphasis> Samylina (Ginkgoales) from the Paleocene of the Tsagayan formation (Amur Region) and the taxonomy of tertiary species of <Emphasis Type="Italic">Ginkgo</Emphasis>

The study of new material on Ginkgo tzagajanica Samylina and earlier published data has shown that the epidermal morphology of the species in highly variable; several new characters were found. Occurrence of different states of characters was analyzed, their frequency distribution was revealed, and typical and rare states of characters within variation rows were determined. The specific diagnosis of G. tzagajanica was emended. The most variable characters are degree of undulation of the anticlinal walls of cells of abaxial and adaxial epidermises (the latter is more variable) and degree of development and number of papillae on ordinary epidermal cells. Less variable characters are degree of development of papillae on subsidiary cells of stomata and how the papillae cover the stomatal apertures. These are characters that bear maximal diagnostic significance for Cenozoic Ginkgo.     

秦岭南坡锐齿栎次生林空间结构特征分析

该研究采用坐标定位方法对秦岭南坡不同坡向锐齿栎次生林样地内胸径DBH≥5cm的乔木进行调查,记录树种名称、坐标、胸径、高度、冠幅、生长状况等因子,运用角尺度、大小比数和混交度3个指数分析不同坡向锐齿栎次生林的空间结构,探寻不同坡向锐齿栎林空间结构的形成和差异。结果显示:(1)调查样地内物种多样性丰富,锐齿栎重要值最大,长势良好,占据主要生态空间。(2)两种坡向中,角尺度取值为0.5的个体数均过半,表明随机分布是锐齿栎次生林的主要分布方式。(3)优势木、亚优势木、中庸木、劣态木和绝对劣态木所占比重均为20%左右,表明林木大小差异不明显,在空间结构单元中,林木较稳定,阳坡优势木个体数高于阴坡。(4)两种坡向中,混交度取值大于0.5林木个体分别为84%和73%,表明多数林木个体处于中度、强度和极强度混交状态。研究表明,秦岭南坡锐齿栎次生林聚集度不高、混交良好、分化程度较高,锐齿栎种群优势度明显,林分整体暂时处于相对稳定状态。     

Changes in fatty acid composition and degree of unsaturation of (brady)rhizobia as a response to phases of growth, reduced water activities and mild desiccation

The effects of growth phase, reductions in the water activity (a _w) of the growth medium and mild desiccation on the composition and the degree of unsaturation of cellular fatty acids (CFA) of Sinorhizobium meliloti, Bradyrhizobium elkaniiand Bradyrhizobium japonicum were studied. During the course of growth, an interchange of cis-vaccenic with lactobacillic acid and a slight increase in palmitic acid were observed while other fatty acids remained constant. The degree of unsaturation was significantly higher in the exponential phase of growth. Reductions in the a _w of the medium led to an increase in lag phase, a reduction in growth rate and maximal optical densities (OD) in stationary phase cells. A decrease in the degree of unsaturation of CFA was also observed as the a _w was reduced from 0.999 to 0.969 and after desiccation to 83.5% relative humidity (R.H.). The changes in the degree of unsaturation of CFA observed after growth at reduced a _w may be one of the pre-adaptation steps to endure more severe desiccation.     

我国民营医院发展现状集聚度评价

目的 对我国各地区民营医院的发展现状进行评价，为推动民营医院发展、民营医疗产业集聚的形成提供参考依据。方法 基于卫生资源集聚度的评价方法，分析我国各地区民营医院集聚度，以及与人口、经济和公立医院集聚度的相关性。结果 （1）经济集聚度较人口集聚度与民营医院集聚度的相关性更大。（2）我国少数地区民营医院集聚度与公立医院集聚度接近，绝大部分地区民营医院集聚度较低、规模偏小。（3）我国民营医院市场中综合医院比重较大，专科医院在经济发达地区集聚度较高。结论 民营医疗产业集聚速度缓慢、规模偏小，亟需政府积极引导，加快民营医疗产业集聚，发挥市场有效配置卫生资源的作用。     

Relationships between the osmoadaptation strategy, amino acid composition of total cellular protein, and properties of certain enzymes of haloalkaliphilic bacteria

Haloalkaliphilic microorganisms isolated from soda lakes were compared in terms of the amino acid composition of total cellular protein and the reaction of a number of key enzymes to salts and pH of the medium. In the extremely halophilic bacterium Natroniella acetigena (salt-inside osmoadaptation strategy), acidic amino acids (glutamic and aspartic) made up 30.91 mol % of the total of cellular protein amino acids. In the moderate haloalkaliphiles Tindallia magadiensis, Halomonas campisalis, and Halomonas sp. AIR-1 (compatible-solutes osmoadaptation strategy), the proportion of acidic amino acids (24.36, 23.15, and 23.58 mol %, respectively) was lower than in N. acetigena but higher than in the freshwater Acetobacterium paludosum (20.77 mol %). The excess of acidic amino acids over basic amino acids (lysine and arginine) increased with the degree of halophily. The enzymes of haloalkaliphiles proved to be tolerant to salts and high pH values, although the degree of tolerance varied. The activity of N. acetigena CO dehydrogenase was maximum in the presence of 0.7 M NaCl, but it was virtually independent of the NaHCO3 concentration. The hydrogenase and CO dehydrogenase of T. magadiensis exhibited maximum activity in the absence of NaCl; the CO dehydrogenase was most active at 0.25 M NaHCO3, and hydrogenase activity was only weakly dependent on NaHCO3 in the concentration range of 0-1.2 M. The nitrate reductases of H. campisalis and Halomonas sp. AIR-2 were active in broad ranges of NaCl and KCl concentrations; the activity maxima were recorded at moderate concentrations of these salts. The pH optima of most of the studied enzymes of haloalkaliphiles were in the alkaline zone. Thus, it was shown that the amino acid composition of total cellular protein is determined by the osmoadaptation strategy employed by the bacterium. A correlation was found between the salt tolerance of enzymes and the proportion of acidic amino acids in the total cellular protein. The ability of enzymes to function at high pH values is one of the mechanisms of adaptation of microorganisms to high pH values.     

<Emphasis Type="Italic">Rhodobaca barguzinensis</Emphasis> sp. nov., a new alkaliphilic purple nonsulfur bacterium isolated from a soda lake of the Barguzin Valley (Buryat Republic,Eastern Siberia)

A novel strain, alga-05, of alkaliphilic purple nonsulfur bacteria was isolated from sediments of a small saline (60 g/l) soda lake near Lake Algin (Barguzin Valley, Buryat Republic, Russia). These bacteria contain bacteriochlorophyll a and carotenoids of the alternative spirilloxanthin group with predominating demethylspheroidenone. They are facultative anaerobes; their photosynthetic structures are of the vesicular type and arranged along the cell periphery. Growth of this strain is possible in a salinity range of 5–80 g/l NaCl, with an optimum at 20 g/l NaCl. Best growth occurred at 20–35°C. Analysis of the 16S rRNA gene sequences demonstrated that the studied isolate is closely related to the alkaliphilic purple nonsulfur bacterium Rhodobaca bogoriensis (99% similarity) isolated from soda lakes of the African Rift Zone. According to the results of DNA-DNA hybridization, strain alga-05 has a 52% similarity with the type species of the genus Rhodobaca. On the basis of the obtained genotypic data and some phenotypic properties (dwelling in a hypersaline soda lake of Siberia, moderate halophily, ability to grow at relatively low temperatures, etc.), the isolated strain of purple bacteria was described as a new species of the genus Rhodobaca, Rca. barguzinensis sp. nov.     

Influence of the glycolipid-producing bacterium Rhodococcus erythropolis on the degradation of a hydrocarbon mixture by an original soil population

Summary The purpose of this investigation was to show whether or no employing a starter culture of the bacterium Rhodococcus erythropolis that produces 6,6-trehalosedicorynomycolates could replace the addition of purified biosurfactant known to accelerate hydrocarbon degradation by an original soil population in a stirred reactor. The rate of degradation, degree of elimination of hydrocarbons, mineralization and degree of oxidation were determined in order to assess the extent of degradation. In comparison with degradation by soil microorganisms only an acceleration of utilization of the hydrocarbons was observed in cultivations of growing cells of R. erythropolis, although the effect of purified trehalosedicorynomycolates is not reached. Except for a higher degree of oxidation a sufficient amount of trehalosedicorynomycolates bound to autoclaved biomass of R. erythropolis does not have any effect.     

Accuracy of self-reported weight among bariatric surgery candidates: the influence of race and weight cycling

Objective: Research on the accuracy of self‐reported weight has indicated that the degree of misreporting (underestimating) weight is associated with increasing weight but is variable across patient groups. We examined the degree of discrepancy between actual and self‐reported BMI in severely obese bariatric surgery candidates, and whether the degree of accuracy varied by race and by eating‐related and psychological factors. Research Methods and Procedures: Participants were 179 obese female gastric bypass surgery candidates (31 black, 22 Hispanic, 126 white) who were asked to self‐report height and weight as part of a larger assessment battery. Actual height and weight were then measured and a discrepancy score was generated (actual BMI ? reported BMI). Results: In this group of severely obese patients, degree of misreporting was unrelated to BMI. The race groups did not differ in actual or self‐reported BMI but differed significantly in the degree of misestimation between self‐reported and actual BMI. Post hoc tests indicated that black women underestimated their BMI significantly more than white women; Hispanic women did not differ from the other race groups. No eating‐related or psychological variables assessed predicted percentage discrepancy; however, the accuracy in self‐reported weight was related to history of weight cycling. Discussion: Overall, obese bariatric surgery candidates were accurate in self‐report of weight, although the degree of accuracy differed by race and weight cycling history.     

Genetic differentiation among three genera of family cercopithecidae

The degree of genetic differentiation among three genera of cercopithecines,Macaca, Papio andCercopithecus, was quantified by the electrophoretic analyses of blood protein variations controlled by 29 genetic loci. The estimates ofNei's standard genetic distance between the pair of species belonging to different genera were in a range of 0.48–0.90. It was found that the degree of genetic differentiation between different genera of cercopithecines was comparable to those between congeneric species of other animal groups. This work failed, however, to determine definitely the branching order of the lineages of the three genera.