Microfluorimetric analysis of dynamics of genomic changes in Chinese hamster fibroblasts CHL V-79 RJK with multiple drug resistance

Results of a karyological analysis of cells CHL V-79 RJK selected for their resistance to ethidium bromide (EB) causing multidrug resistance (MDR) (subline Vebr-5) were compared with data from the microfluorimetric determination of the DNA content in individual chromosomes of the karyotype. The analysis was performed at the 11th and 88th passages. Karyotyping of Vebr-5 has shown the presence of an additional genetic material (AGM) in the form of homogenously or differentially stained regions (HSR or DSR, respectively) in two chromosomes (Z1 and Z6, loci 1p29-31 and 1q26, respectively). HSR in Z6, in the site of localization of the mdr gene of the wild type had unstable length and structure, which is characteristic of the morphological markers of the amplification of genes of the mdr family. During the long cultivation of Vebr-5 in the presence of EB (88 passages), the instability of HSR (DSR) in Z6 increased. Results of a microfluorimetric analysis of Vebr-5 at the 11th passage have shown a statistically significant increase of the DNA content not only in chromosomes Z1 and Z6 marked by HSR (DSR), but also in three chromosomes (Z5, Z12, and Z13) that have no visual morphological changes. The corresponding analysis at the 88th passage has also revealed nonrandom changes in the DNA content in four more chromosomes, including an increase in Z14 and a decrease in chromosomes 8, Z7, and Z9. A decrease in the DNA content in chromosomes is considered to be the result of a partial loss of genetic material, while its increase is considered to be the result of its translocation and/or amplification. While the coefficient of the variation of the DNA content changes about 9% for large chromosomes, it amounted to about 26% for the small ones, indicating that small chromosomes to have a greater potential for instability than large chromosomes. The obtained data not only confirm, but also enlarge, the concept of the directions and character of the destabilization of the cell genetic apparatus in the process of neoplastic transformation due to MDR acquisition by these cells.     

Human embryonal prealbumin-1. Chemical and immunochemical characteristics

General chemical and immunochemical characterization of human embryonic prealbumin-1 (EPA-1) isolated from abortive blood is presented. EPA-1 was found to exist as glycosylated and non-glycosylated forms, which are immunochemically identical. Sugar moiety of the glycosylated form contains residues of fucose (3.0%), mannose (3.2%), galactose (7.8%), N-acetylglucosamine (5.4%), N-acetylgalactosamine (1.2%) and N-acetylneuraminic acid. Using methylation studies, types of bonds between the sugar residues were elucidated.     

Distribution of N<Superscript>6</Superscript>-Methyladenine in DNA of T2 Phage and its Host <Emphasis Type="Italic">Escherichia coli</Emphasis> B

N⁶-METHYLADENINE (6-MeAde) and 5-methylcytosine occur as minor bases in bacterial and phage DNA^1–7 and seem to result from the selective methylation of adenine and cytosine residues by specific DNA methylases⁸. Methylation is the final stage in DNA synthesis and is essential for the phenomenon of host modification of phages^9–11; it is one of the mechanisms controlling DNA replication in the cell^{12, 13}. A study of the distribution of minor bases in DNA is therefore important not only for the elucidation of the specificity and mechanism of action of DNA methylases but also for an understanding of the purpose of this methylation. We believe that in Escherichia coli, DNA methylase exerts its action on adenine residues in chain terminating triplets: 6-MeAde may serve as a signal for gene termination in this system.     

Diversity of the mitochondrial DNA cytochrome b gene of the field mouse Apodemus agrarius Pallas, 1771 in the south of the Russian Far East

We studied the variability of a fragment of the cytochrome b gene and the corresponding amino acid sequence of the field mouse Apodemus agrarius (Pallas, 1771) in the South of Primorskii krai (Far East of Russia). A significant polymorphism of these traits was detected. High indices of molecular diversity were obtained. The topology of the phylogenetic tree and the median networks suggest that the population of field mice in the south of Primorskii krai originated from three maternal lines. It was noted that clustering of haplotypes on a territorial basis is absent, and the field mouse population in southern Primorskii krai can be considered as one of the key points in maintaining a high genetic diversity of the species.     

Immunochemical and physico-chemical characteristics of glycoprotein from retroplacental blood having several common antigenic determinants with trophoblastic beta 1-glycoprotein

A glycoprotein (TSG-fs) isolated from retroplacental blood is shown to have common antigenic determinants with trophoblast-specific beta 1-glycoprotein (TSG, SP-1). Antigenic activity of TSG-fs constitute 3.4% of TSG's activity. Like TSG, glycoprotein TSG-fs contains four intramolecular disulfide bonds and belongs to proteins with predominantly beta-structure. CD-spectroscopy data give evidence of high stability of the secondary structure of TSG-fs. Immunochemical identity of TSG-fs with the reduced and carboxymethylated derivative of TSG has been demonstrated. The above data allow to suggest that TSG-fs is a fragment of the TSG molecule.     

壳多孢属的一个新种

1979年9月在沈阳地区的翅果油树 Elaeagnus mollis 植株上发现壳多孢属的一个新种,定名为胡颓子壳多孢(Stagonospora elaeagni Y.Gao sp.nov.)。     

The significance of the mu- and delta-opiate receptors in realizing enkephalin action on the course of hypoxic hypoxia]

New enkephalins analogues have been synthesized. They are characterized by linear, cyclic and branched peptide chain. A relationship has been established between antihypoxic activity of opioid peptides an their interaction with opiate receptors. Compounds efficiently interacting with mu-receptors irrespective of delta-receptors affinity, promote longer survival of mice in hypoxia. The antihypoxic effect of opioids is proportional to their specificity to mu-receptors.     

Effect of tetraethylammonium intracellular microiontophoretic injection on activity of the crayfish stretch receptor

Our investigation of the slow-adapting neurons of the crayfish abdominal receptor organ has revealed that intracellular microiontophoretic injection of tetraethylammonium induces no changes in the receptor potential of the neurons. The results obtained show that tetraethylammonium-sensitive potassium channels are not important for adaptation manifested by primary receptor responses of mechanosensitive neurons.Translated from Neirofiziologiya, Vol. 25, No. 2, pp. 91–94, March–April, 1993.