Asymmetry in the frequencies of reciprocal recombinants in crosses of T4 phage rIIB mutants]

The frequencies of reciprocal recombinants in crosses between rIIB mutants of T4 phage were shown to differ from each other. In terms of the correction model, this asymmetry of genetic recombination was used to measure the comparative correctability of the mismatched regions to the wild type and to the mutant alleles. The data obtained are in quantitative agreement with the analogous values for the same mismatched regions determined by comparison of the markers located at the same site. This strongly suggests that the asymmetry of genetic recombination in T4 reflects the corresponding difference in rates of correction of the mismatched regions in heteroduplexes in opposite directions.     

Synthesis and antiproliferative activity of a novel N-acyl derivative of doxorubicin]

Doxorubicin was acylated with estrone 3-hemisuccinate. The modified derivative exhibited high antiproliferative activity in vitro toward cell cultures of the MCF-7 human mammary adenocarcinoma and HepG2 human hepatoma.     

Microbial Degradation of Mustard Gas Reaction Masses: Isolation and Selection of Degradative Microorganisms,Analysis of Organic Components of Reaction Masses,and Their Biodegradation

Bacterial strains growing in medium with mustard gas reaction masses (RM) as the carbon source were obtained. Growth cessation in the above medium was caused by the exhaustion of bioutilizable substrates, first of all monoethanolamine (MEA) and ethyleneglycol (EG), rather than by the accumulation of toxic metabolites in the culture liquid or in the cells. The main RM components, 1,4-perhydrothiazines (PHT), formed in the course of chemical detoxication of mustard gas, were identified and analyzed. The predominant component of the PHT mixture was N-(2-hydroxyethyl)-2-methyl-1,4-perhydrothiazine hydrochloride. Concentrations of all the PHT decreased by 50% in the course of culture growth; their destruction was a result of microbial metabolism.     

Arachnids from the Carboniferous of Russia and Ukraine,and the Permian of Kazakhstan

New finds of Late Palaeozoic arachnids, based on three well-preserved carapaces from the Carboniferous of Russia and Ukraine and one complete, albeit poorly preserved, specimen from the Permian of Kazakhstan, are described. The spider genus Arthrolycosa is reported from the Late Carboniferous (Late Pennsylvanian: Kasimovian–Gzhelian) of Chunya in the Tunguska Basin of Siberia; it is the first find of a spider outside the Carboniferous tropics. Another fossil assigned to the same genus comes from the Late Carboniferous (Early Pennsylvanian: Bashkirian) of Kamensk–Shakhtinsky in the Donets Basin of Russia; it is probably the oldest fossil spider known. A thelyphonid (whip scorpion) carapace is described from the Late Carboniferous (Late Pennsylvanian: Kasimovian) of the adjacent Lugansk Province of the Donets Basin of Ukraine.     

A scanning cytophotometer for the analysis of closely contiguous objects

A measuring complex including microscope-photometer and computer is described to be used for scanning of a sample inside of an arbitrary contour. The complex is supplied with a television channel for simultaneous control of the sample and photometric diaphragm, and also with a manual manipulator for setting the boundaries of the informational zone. At the end of scanning the cytophotometric and morphometric data are registered.     

Accumulation of hydrogen peroxide and functioning of defense system in overwatered barley seedlings

The effects of overwatering (flooding) on the oxidative potential, the level of low-molecular-weight antioxidants, the content of stress proteins, and activities of antioxidant enzymes in green barley (Hordeum vulgare L.) seedlings were studied. Overwatering retarded barley seedling growth and induced hydrogen peroxide accumulation, a decrease in the total ascorbate content and an increase in the content of reduced glutathione (GSH), but it did not affect the content of oxidized glutathione (GSSG). After the cessation of stress factor action (post-stress period), the content of hydrogen peroxide declined to the initial level, the content of ascorbate reduced still stronger, whereas the content of GSH continued to rise. Under flooding conditions, activities of glutathione reductase (GR) and superoxide dismutase (SOD) increased. After the cessation of stress factor action, activities of these enzymes decreased but remained at rather high levels as compared with control. Activity of catalase (CAT) reduced during stress, whereas activity of ascorbate peroxidase (APX) was not essentially changed. In the post-stress period, CAT activity remained to be low; in contrast, APX activity increased. Barley seedling flooding induced the synthesis of stress proteins, HSP70 and dehydrins (DH). In the post-stress period, the content of stress proteins decreased; however, the content of DH in experimental leaves remained rather high. The results obtained indicate that barley defense system manifested a complex response to overwatering, which may be related to the oxygen shortage under stress conditions and sharp metabolism activation at re-aeration in the post-stress period.     

Origin of Kupffer macrophages in the regenerating liver

Male Wistar rats were injected intraperitoneally with H3-thymidine (5 muC/g). Two thirds of the liver was removed one hour later. Sham operated animals served as control. A moderate elevation of the labeled nuclei indices of hepatocytes (LNI) was seen by the third hour, increased significantly by the ninth, and especially by the 24th hour after the operation. The indices decreased by the 48th hour after partial hepatectomy. In 3 hours the LNI was 10 times higher than in the control; in 9 hours it reached the maximum, decreasing by the 24th and 48th postoperative hours. The origin of Kupffer's macrophages in the regenerating liver is discussed.