Uptake of galactose by the yeast during its utilization

Изучался транспорт галактозы дрожжами ?асснагомусе? сегев???ае R XII, адаптированными к этому сахару. Было установлено, что при наших условиях опыта галактоза находится в клетках в свободном, нефосфорилированном состоянии как в условиях, когда этот сахар не используется, так и в условиях, когда он используется. В наших условиях опыта наблюдалась деадаптация использования галактозы. В течение адаптации и деадаптации транспорт свободной галактозы в клетки не был наиболее медленным процессом ее использования.     

Uptake of galactose-1-14C bySaccharomyces cerevisiae R XII

Summary The uptake of galactose-1-¹⁴C by the yeastSaccharomyces cerevisiae R XII was investigated and it was found that even at low external concentrations (down to 2×10⁻⁴M) the transport of the sugar proceeds only down its concentration gradient. The relationship of the initial rate of galactose uptake and of its uptake in equilibrium to external concentration is linear. The results confirm the conclusions reached about the uptake of sugars by yeast cells on the basis of experiments with higher sugar concentrations.

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Транспорт галактозы-1-¹⁴C в Saccharomyces cerevisiae R XII

При изучении трнаспорта галактозы-1-¹⁴C в клетки грибков Saccharomyces cerevisiae R XII было доказано, что даже при низ ких концент рациях (вплоть до 2.10⁻⁴ M) речь идет всегда о переносе сахаров в направлении градиента концентрации, а не против него. Зависимость первона чальной скорости транспорта галактозы и скорости вступления в состояние равновесия прямо пропорциональна концентрации. Результаты опытов подтверждают правильность выводов относительно транспорта сахаров в дрожжевые грибки, сделанных на основании опытов с более высокими концентрациями в среде.

     

Remodelling of the sarcolemma in diabetic rat hearts: The role of membrane fluidity

The hyperglycaemia and oxidative stress, that occur in diabetes mellitus, cause impairment of membrane functions in cardiomyocytes. Also reduced sensitivity to Ca-overload was reported in diabetic hearts (D). This enhanced calcium resistance is based on remodelling of the sarcolemmal membranes (SL) with down-regulated, but from the point of view of kinetics relatively well preserved Na,K-ATPase and abnormal Mg- and Ca-ATPase (Mg/Ca-ATPase) activities. It was hypothesised that in these changes may also participate the non-enzymatic glycation of proteins (NEG) and the related free radical formation (FRF), that decrease the membrane fluidity (SLMF), which is in reversal relationship to the fluorescence anisotropy (D 0.235 ± 0.022; controls (C) 0.185 ± 0.009; p < 0.001). In order to check the true role of SLMF in hearts of the diabetic rats (streptozotocin, single dose, 45 mg/kg i.v.) animals were treated in a special regimen with resorcylidene aminoguanidine (RAG, 4 mg/kg i.m.). The treatment with RAG eliminated completely the diabetes-induced decrease in the SLMF (C 0.185 ± 0.009; D + RAG 0.167 ± 0.013; p < 0.001rpar; as well as in NEG (fructosamine g.mg^–1 of protein: C 2.68 ± 0.14; D 4.48 ± 0.85; D + RAG 2.57 ± 0.14; p < 0.001), and FRF in the SL (malondialdehyde: C 5.3 ± 0.3; D 8.63 ± 0.2; D + RAG 5.61 ± 0.53 mol.g^–1; p < 0.05). Nevertheless, the SL ATPase activity in diabetic animals was not considerably influenced by RAG (increase in D + RAG vs. D 3.3%, p > 0.05). On the other hand, RAG increased considerably the vulnerability of the diabetic heart to overload with external Ca²⁺ (C 100% of hearts failed, D 83.3%, D + RAG 46.7% of hearts survived). So we may conclude, that: (i) The NEG and FRF caused alterations in SLMF, that accompanied the diabetes-induced remodelling of SL, also seem to participate in the protection of diabetic heart against Ca²⁺-overload; (ii) Although, the changes in SLMF were shown to influence considerably the ATPase activities in cells of diverse tissues, they seem to be little responsible for changes in ATPases-mediated processes in the SL of chronic diabetic hearts.     

Uptake of metabolizable sugars bySaccharomyces cerevisiae

1. (1)
   Сахара (галактозу, глюкозамин), используемые дрожжами Saccharomyces cerevisiae, можно найти в клетках в свободном состоянии, если скорость их поступления больше, чем скорость их потребления.     

Yeast Colony Survival Depends on Metabolic Adaptation and Cell Differentiation Rather Than on Stress Defense

Enzymes scavenging reactive oxygen species (ROS) are important for cell protection during stress and aging. A deficiency in these enzymes leads to ROS imbalance, causing various disorders in many organisms, including yeast. In contrast to liquid cultures, where fitness of the yeast population depends on its ROS scavenging capability, the present study suggests that Saccharomyces cerevisiae cells growing in colonies capable of ammonia signaling use a broader protective strategy. Instead of maintaining high levels of antioxidant enzymes for ROS detoxification, colonies activate an alternative metabolism that prevents ROS production. Colonies of the strain deficient in cytosolic superoxide dismutase Sod1p thus developed the same way as wild type colonies. They produced comparable levels of ammonia and underwent similar developmental changes (expression of genes of alternative metabolism and center margin differentiation in ROS production, cell death occurrence, and activities of stress defense enzymes) and did not accumulate stress-resistant suppressants. An absence of cytosolic catalase Ctt1p, however, brought colonies developmental problems, which were even more prominent in the absence of mitochondrial Sod2p. sod2Δ and ctt1Δ colonies failed in ammonia production and sufficient activation of the alternative metabolism and were incapable of center margin differentiation, but they did not increase ROS levels. These new data indicate that colony disorders are not accompanied by ROS burst but could be a consequence of metabolic defects, which, however, could be elicited by imbalance in ROS produced in early developmental phases. Sod2p and homeostasis of ROS may participate in regulatory events leading to ammonia signaling.     

Cochlear hair-cell populations and limits of resolution of hearing in two vespertilionid bats,Nyctalus noctula and Eptesicus serotinus

A comparison of the population of cochlear hair cells with known hearing resolution capabilities in two species of bats (Nyctalus noctula and Eptesicus serotinus of the family Vespertilionidae) has revealed a close correlation between morphological and functional parameters. Data on number and densities of hair cells in the examined bat species are presented. Even though the species are of a comparable body size, N. noctula has a longer basilar membrane, a higher density, and hence also a higher total number of hair cells than E. serotinus. This is in good agreement with hearing resolution capabilities, which are better in N. noctula than in E. serotinus. These findings have implications on differences in feeding ecology and hunting strategies between these species.     

Metabolites ofStreptomyces noursei

The production variability of secondary metabolites was studied after treatment with mutagenic factors. 852 isolates were examined, out of which 308 after X-irradiation, 277 after u. v.—irradiation and 267 after treatment with nitrogen mustard. According to the production of individual secondary metabolites examined it was possible to divide the strains obtained into 4 groups.     

In Vivo and In Vitro Function of the Intracellular Proteolytic Apparatus in Nongrowing Bacillus megaterium Under Heat Stress

In Bacillus megaterium sporulating at 35°C, up to 90% of 10-min pulse-labeled proteins were degraded. Degradation proceeded in two waves. Short-lived proteins, i.e., intrinsically labile proteins and proteins made short-lived because of starvation, were mostly degraded during the reversible sporulation phase. Their amount corresponded to 20% or slightly more during 2 h. The second wave of protein degradation, which followed during the irreversible sporulation phase at 35°C, increased the amount of total degradable pulse-labeled proteins to about 90%. This wave was absent in the isogenic asporogenic mutant 27-36 or in the wild strain, whose sporulation was inhibited by increased temperature. The proportion of degradable proteins was thus reduced to less than 40% in the asporogenic mutant incubated at 35°C and to 46% in the wild strain whose sporulation was suppressed by the temperature of 47°C. Unlike sporulating cells, these cells were thus capable of degrading short-lived and denatured proteins, but were not able to degrade most of other proteins. The in vitro protein degradation was substantially enhanced by increasing the Ca²⁺ concentration, suggesting a role of Ca²⁺-dependent proteinase(s) in the process. Received: 23 July 1998 / Accepted: 19 August 1998     

Antagonistic properties and mutual relationships of some actinomycetes

Вгруппе из 93 изолированных свежевыжатые Анта-следующий символ-были исследованы: таксономия, антибиотик свойствами, характер производства антибиотиков и взаимоотношений-корабли между отдельными штаммов. Нумер ическом идентичные штаммы Альбус и helvolus се рии отличаются производства-ЛОР виды антибиотиков. Количественная представительства производителей антибиотиков не отличается только в два таксономических рядов, но и в некоторых из своих групп. Насколько их взаимные отношения беспокоит Наиболее эффективным и антагонистов в же время наиболее чувствительными измов являются те производства антибиотиков от типа и штаммов с анти-были весьма устойчивы. Взаимная реальном-страдали в различной степени питательных веществ в среднесрочной. Восемь штаммов отображаются торый был в-путем среднеи питательных веществ Длина культивирования. Штаммов экспонирование были мешать последо вательных штаммов производство противопехотных-одн ой и той же группы, как свою собственную. Обсуждение проблем возможностей микроорганизмов, обладающих различными антибиотика в различных свойств в-условиям и новым методом от возможного применения антибиотика свойств за их классификации или систематике.