Influence of intermittent normobaric hypoxia during early organogenesis on the development of white rats

The influence of antenatal intermittent normobaric hypoxia during early organogenesis (days 9–10 of intrauterine development) on the physical development, vegetative balance, and antioxidant defense system of 60-day-old rats was studied. Antenatal exposure to intermittent hypoxia resulted in the impaired physical development of all offspring during the early 15-day postnatal period and caused changes in the vegetative balance of heart regulation, which were differently directed in males and females. Moreover, females that survived antenatal hypoxia had a decreased superoxide dismutase activity in the brain, compared to that in the control rats.     

用抗性筛选法选育γ—亚麻酸（GLA）高产菌株

以深黄被孢霉（Mortierella isabellina）为出发菌株,经紫外线诱变处理,采用抗性筛选法,直接在梯度平板上挑选取抗脂肪酸脱氢酶抑制物抑芽丹（maleic hydrazide）的菌株进行初筛,然后经摇瓶发酵法测定相关性能指标进行得筛,获得一株生产性能比出发菌株显提高的突变株M80,其菌体收率达25.10g/L、油脂产率达12.35g/L、γ-亚麻酸（GLA）产率达771.88mg/L。     

Bacterial toxin-antitoxin systems and perspectives for their application in medicine

The structure of various toxin-antitoxin (TA) families and the principles of their action are reviewed. TA loci are widely distributed in the genomes of eubacteria and archaea. Most TA systems are two-component and function in a similar way: a stable toxin alters vitally important cell functions and can be inactivated by a labile antitoxin.     

Changes of glucocorticoid level in plasma and adrenal glands of pregnant rats and their offspring after antenatal stress of different etiology

We investigated the glucocorticoid level in plasma and adrenal glands of pregnant rats in the period of early organogenesis. Tests were performed 24 hours after stress of different etiology (acute hypobaric hypoxia, intermittent normobaric hypoxia, and immobilization) and then repeated in the adult offspring. There was a significant decrease in the glucocorticoid level in pregnant rats 24 hours after hypoxic stress. Various changes of the basal glucocorticoid level were found in the offspring after antenatal stress. Changes were mostly found in female offspring.     

Horizontal transmission, vertical inactivation, and stochastic loss of mariner-like transposable elements

Horizontal transmission has been well documented as a major mechanism for the dissemination of mariner-like elements (MLEs) among species. Less well understood are mechanisms that limit vertical transmission of MLEs resulting in the "spotty" or discontinuous distribution observed in closely related species. In this article we present evidence that the genome of the common ancestor of the melanogaster species subgroup of Drosophila contained an MLE related to the mellifera (honey bee) subfamily. Horizontal transmission, approximately 3-10 MYA, is strongly suggested by the observation that the sequence of the MLE in Drosophila erecta is 97% identical in nucleotide sequence with that of an MLE in the cat flea, Ctenocephalides felis. The D. erecta MLE has a spotty distribution among species in the melanogaster subgroup. The element has a high copy number in D. erecta and D. orena, a moderate copy number in D. teissieri and D. yakuba, and was apparently lost ("stochastic loss") in the lineage leading to D. melanogaster, D. simulans, D. mauritiana, and D. sechellia. In D. erecta, most copies are concentrated in the heterochromatin. Two copies from D. erecta, denoted De12 and De19, were cloned and sequenced, and they appear to be nonfunctional ("vertical inactivation"). It therefore appears that the predominant mode of MLE evolution is vertical inactivation and stochastic loss balanced against occasional reinvasion of lineages by horizontal transmission.      

Intra- and interspecific genetic differentiation in closely related pines fromPinus subsectionSylvestres (Pinaceae) in the former Soviet Union

Thirty-seven natural populations of four closely related species ofPinus subsect.Sylvestres, P. mugo, P. funebris, P. pallasiana, andP. sylvestris, occurring in the former Soviet Union were investigated by starch-gel electrophoresis. In the populations assayed 127 allelic variants at 25 loci were revealed.Nei's distance coefficient (Dn) was used to estimate the level of genetic differentiation amongP. sylvestris races and among closely related species. A dendrogram constructed using Dn values shows that of the fiveP. sylvestris races analyzed only the geographically isolated var.hamata exhibited sufficient differences at theDia-2 locus (a mean Dn value relative to the other four races is 0.025) to recognize it as a distinct taxon. The remaining races, sylvestris, cretacea, lapponica, and sibirica, have a similar gene pool (Dn values are not greater than 0.010), and they should be regarded as a single taxon,P. sylvestris var.sylvestris. Interspecific comparisons revealed thatP. sylvestris andP. mugo have the closest genetic affinities to each other withNei's genetic distance of 0.108. The dendrogram demonstrates thatP. funebris is closer toP. sylvestris andP. mugo thanP. pallasiana. The available paleontologic data allowed us to conclude thatNei's (1975) time scale estimate for the time of divergence of the taxa was more accurate thanNei's (1971) time scale estimate.     

Population structure,gene diversity,and differentiation in natural populations of Cedar pines (Pinus subsect.Cembrae,Pinaceae) in the USSR

Twelve natural populations of four cedar pine species,Pinus sibirica, P. cembra, P. pumila, andP. koraiensis, occurring in the Soviet Union were investigated by starch-gel electrophoresis. Frequencies of 55 alleles at 19 loci were determined. Interpopulation genetic diversity inP. sibirica andP. pumila was only 2–4 per cent of the total genetic diversity. Nei's distance coefficient (Dn) was used to estimate the level of genetic differentiation among conspecific populations and among species. Dn values among populations ranged from 0.006 to 0.038. A dendrogram constructed using Dn values divided cedar pines species into 2 clusters:sibirica-cembra (Dn = 0.030) andpumila-koraiensis (Dn = 0.143). Nei's distance between these clusters was 0.232. On the basis of the data obtained it was possible to draw the following conclusion:P. sibirica, P. pumila, andP. koraiensis are distinct species, whileP. cembra should apparently be regarded as geographicalP. sibirica race.     

The morphological changes in a primary culture of 3-day-old rat hepatocytes cultured over 1 week and in a model of anoxia

A direct observation of primary cultures of 3-day-old rat hepatocytes was performed with the help of time-consuming cinematography. The process of monolayer formation has been examined. In addition, the continuous preservation of bile canaliculi was observed. A significant increase in hepatocyte mobility was marked in 6-7-day cultures. The structural analysis of cultured cells during the modelling of anoxia with substrate deficiency revealed a succession in hepatocyte and fibroblast alterations. The hepatocyte destruction was accompanied with changes in the cell form, that become rounded, and in the appearance of small formations protruding on the cell surface. The fibroblast destruction appeared after cell contracture.     

Effect of radioprotectors on lipid peroxidation in liver microsomes induced by ultraviolet irradiation of the skin in rats

The modifying effect of radioprotectors (serotonin, cysteamine, ionol) on lipid peroxidation intensification of liver microsomes caused by rat skin ultraviolet radiation has been studied. A possible mechanism of action of these compounds on the investigated indexes during their preventive injection is under discussion.