Effect of radiation on cell interactions in the phenomenon of non-syngeneic stem cell inactivation. Changes in B-lymphocyte function after irradiation

A study was made of the changes in the mode of interaction between T- and B-lymphocytes of mouse lymph nodes with respect to the phenomenon of inactivation of non-syngeneic haemopoietic stem cells. It was shown that irradiation of B-lymphocytes with doses of 77.4--232.2 mC/kg changes their helper activity into a suppressor activity with regard to T-cell-killers having a low electrophoretic mobility.     

Segmental flexibility of single-, double-, and triple-stranded polyribonucleotides from the data of spin label method. Formation of the triple-stranded poly(A.A.U) polynucleotide helix

Segmental mobility dynamic peculiarities of poly(U), poly(A) and poly(C) synthetic polymers and their complexes were investigated by spin-label method. Imidazolide spin-label was introduced into 2'-oxi-groups of polymer ribose in correlation: one spin-label on 18-20 bases. Formation of complexes was observed by ESR spectra at two pH: 4.2 and 7.2. Segmental mobility of only single strand spin-labelled polymer segment and in the complex was evaluated by measuring rotational correlation time (tau) determined by dependence of distances between outer wide extrema in ESR spectra from solvent viscosity at different temperatures. It turned out that correlation time tau of single strand structures in a high degree depend on pH and temperature. For three strand structures abrupt increase of tau because of appearance of rigidity was observed. It is possible to evaluate part of triple complexes poly(U.A.A) and poly(U.U.A) existing in dynamic equilibrium depending on pH and temperature by the form of outer wide extrema. Adding of dye to complex of poly(U).poly(A) causes an increase of rigidity of the supermolecular structure. Quantitative characteristics of formed complexes were obtained by simulation of ESR spectra on computer.     

Modern variations of human influenza group A viruses at the molecular level]

The authors own results on the variety of the genomic primary structures in human influenza A viruses participating in the epidemic process, including the atypical viruses. The comparative studies revealed new trends in the HA gene antigenic drift on the late stages and the PB1 gene shift. Modifications occurring in the primary structure of the influenza A viruses native genomes during laboratory treatment (adaptation to new hosts, vaccine preparation, egg passaging) have been analyzed. Sequencing of several types of "antigenic anachronisms" revealed the direct links between some of such viruses and the anthropogenic pollution of the biosphere by vaccine strains. Modifications in the HA genes of influenza A viruses during the persistent infection have also been studied.     

THE LASER TOMOGRAPHICAL METHOD USINGMINIMUM OF PROJECTION FOR BIOLOGICAL OBJECT STRUCTURE STUDY

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Anticytokinin activity of 4-substituted triazolo[4,5-d]pyrimidines and 4-substituted pyrazolo[3,4-d]pyrimidines

The synthesis and physiological activity of some novel 4-substituted triazolo[4,5-d]pyrimidines and 4-substituted pyrazolo[3,4-d]pyrimidines are described. Most of the compounds possessed high anticytokinin activity towards purine (benzyladenine) and phenylurea (4-PU-30) type cytokinins. 1-Benzyl-4-ethoxycarbonylpiperazinyl-1H-1,2,3-triazolo[4,5-d]pyrimidine almost completely removed cytokinin stimulated effects—betacyanin synthesis in Amaranthus caudatus cotyledons; growth of radish cotyledons and retention of chlorophyll in leaf explants. Some chemical structurephysiological activity relationships have been established.     

Genomic regulation of transposable elements in Drosophila

Transposable elements are a major source of genetic change, including the creation of novel genes, the alteration of gene expression in development, and the genesis of major genomic rearrangements. They are ubiquitous among contemporary organisms and probably as old as life itself. The long coexistence of transposable elements in the genome would be expected to be accompanied by host-element coevolution. Indeed, the important role of host factors in the regulation of transposable elements has been illuminated by recent studies of several systems in Drosophila. These include host factors that regulate the P element, a host mutation that renders the genome permissive for gypsy mobilization and infection, and newly induced mutations that affect the expression of transposon insertion mutations. The finding of a type of hybrid dysgenesis in D. virilis, in which multiple unrelated transposable elements are mobilized simultaneously, may also be relevant to host-factor regulation of transposition.