Specific resistance and electrophoretic mobility of regenerating liver cells. Effect of ribonuclease and neuraminidase]

Changes of specific resistance and electrophoretic mobility of the cells from regenerative liver of rats are investigated. It is shown that specific resistance decreases and electrophoretic mobility increases during 30 h after hepathectomy. Exogenous ribonuclease decreases electrophoretic mobility by 10% and does not reduce significantly specific resistance. Neuraminidase treatment caused a marked increase (approximately 40%) of specific resistance without reduction in the mobility of cells from both intact and regenerative liver. It is concluded that there is no difference in the sensitivity of the cell surface of normal and regenerative liver to ribonuclease and neuraminidase.     

Radiation protective properties of a synthetic antagonist of glucocorticoids RU 38486]

Radioprotective properties of synthetic antiglucocorticoid RU 38,486 were investigated. It was demonstrated that this antagonist of glucocorticoids possesses radioprotective effect in vitro and in vivo systems. Radioprotective properties at molecular level exhibited in inhibition of postirradiation endonuclease activation and in prevention of internucleosome chromatin degradation. Involvement of cytosol glucocorticoid receptors in initiation of radiation-induced programmed cell death is discussed.     

Systematics of spiny‐backed treefrogs (Hylidae: Osteocephalus): an Amazonian puzzle

Spiny‐backed tree frogs of the genus Osteocephalus are conspicuous components of the tropical wet forests of the Amazon and the Guiana Shield. Here, we revise the phylogenetic relationships of Osteocephalus and its sister group Tepuihyla, using up to 6134 bp of DNA sequences of nine mitochondrial and one nuclear gene for 338 specimens from eight countries and 218 localities, representing 89% of the 28 currently recognized nominal species. Our phylogenetic analyses reveal (i) the paraphyly of Osteocephalus with respect to Tepuihyla, (ii) the placement of ‘Hyla’ warreni as sister to Tepuihyla, (iii) the non‐monophyly of several currently recognized species within Osteocephalus and (iv) the presence of low (<1%) and overlapping genetic distances among phenotypically well‐characterized nominal species (e.g. O. taurinus and O. oophagus) for the 16S gene fragment used in amphibian DNA barcoding. We propose a new taxonomy, securing the monophyly of Osteocephalus and Tepuihyla by rearranging and redefining the content of both genera and also erect a new genus for the sister group of Osteocephalus. The colouration of newly metamorphosed individuals is proposed as a morphological synapomorphy for Osteocephalus. We recognize and define five monophyletic species groups within Osteocephalus, synonymize three species of Osteocephalus (O. germani, O. phasmatus and O. vilmae) and three species of Tepuihyla (T. celsae, T. galani and T. talbergae) and reallocate three species (Hyla helenae to Osteocephalus, O. exophthalmus to Tepuihyla and O. pearsoni to Dryaderces gen. n.). Furthermore, we flag nine putative new species (an increase to 138% of the current diversity). We conclude that species numbers are largely underestimated, with most hidden diversity centred on widespread and polymorphic nominal species. The evolutionary origin of breeding strategies within Osteocephalus is discussed in the light of this new phylogenetic hypothesis, and a novel type of amplexus (gular amplexus) is described.     

Effects of red ginseng extract on sleep architecture and electroencephalogram power spectra in rats

Sleep and Biological Rhythms - We evaluated the ability of the ethanol extract of red ginseng (RGE) to regulate sleep architecture. Adult rats were chronically fitted with sleep-wake recording...     

Molecular mechanism of the action of lucanthone on tumor and normal cells]

The standard analytical and preparative electrophoresis in polyacrylamide gel did not reveal qualitative differences in the fraction composition of c-RNA of the ascitic tumour cells (Zaidel hepatoma, Ehrlich carcinoma, NK/ly lymphoma) and normal liver cells. In vitro the tumour and normal cells efficiently incorporated the labeled uridine into the all main classes of c-RNA (4S, 18S, 28S, fractions above 28S), the process being more intensive in the tumour cells. The presence of tumours in the animal organism had a significant effect on RNA biosynthesis in the liver, the effect being dependent on the tumor nature. Lucantone (miracyl D) had practically no effect in vitro on the quantitative content of the summation c-RNA and its fractions in all cells studied. However, it markedly inhibited the metabolism of the main fractions of c-RNA in the cells of Zaidel hepatoma and Ehrlich carcinoma. The effect of lucatone in the cells of NK/ly lymphoma was contrary.     

Crystal structure of the fungal nitroreductase Frm2 from Saccharomyces cerevisiae

Nitroreductases are flavoenzymes that catalyze nitrocompounds and are widely utilized in industrial applications due to their detoxification potential and activation of biomedicinal prodrugs. Type I nitroreductases are classified into subgroups depending on the use of NADPH or NADH as the electron donor. Here, we report the crystal structure of the fungal nitroreductase Frm2 from Saccharomyces cerevisiae, one of the uncharacterized subgroups of proteins, to reveal its minimal architecture previously observed in bacterial nitroreductases such as CinD and YdjA. The structure lacks protruding helical motifs that form part of the cofactor and substrate binding site, resulting in an open and wide active site geometry. Arg82 is uniquely conserved in proximity to the substrate binding site in Frm2 homologues and plays a crucial role in the activity of the active site. Frm2 primarily utilizes NADH to reduce 4‐NQO. Because missing helical elements are involved in the direct binding to the NAD(P)H in group A or group B in Type I family, Frm2 and its homologues may represent a distinctive subgroup with an altered binding mode for the reducing compound. This result provides a structural basis for the rational design of novel prodrugs with the ability to reduce nitrogen‐containing hazardous molecules.