[The structure of chromatin at meiotic prophase I].

The qualitative and quantitative changes in molecular chromatin structures during the meiotic prophase I were studied. The following patterns were discovered: (1) unlike somatic cells, the syntheses of total histone and DNA and its integration into the chromatin occur independently and asynchronously: DNA replication is completed by the interphase, whereas the synthesis of histone and its integration into the chromatin continue to late meiotic prophase I, and (2) individual histone fractions are synthesized and integrated into the chromatin during meiotic prophase independently and asynchronously. Chromatin hydrolysis with nucleases DNI, STN, and SI demonstrated considerable differences in the hydrolysis products obtained at different stages of the meiotic prophase I; presumably, this reflects the differences between the structures of initial chromatin at different stages of the meiotic prophase I.

[Expert diagnosis of infectivity with the AIDS virus using immune blotting: the development of a system and assessment of its parameters]. / Ekspertnaia diagnostika infitsirovannosti virusom SPID s pomoshch'iu immunnogo blotinga: razrabotka sistemy i otsenka ee paranetrov.

A system for serodiagnosis of infection with AIDS viruses by means of immune ("western") blotting has been developed. The system has been found to be highly sensitive and suitable for expert serodiagnosis of AIDS disease and infection with human AIDS viruses.

Primary organization of nucleosomal core particles is invariable in repressed and active nuclei from animal, plant and yeast cells.

A refined map for the linear arrangement of histones along DNA in nucleosomal core particles has been determined by DNA-protein crosslinking. On one strand of 145-bp core DNA, histones are aligned in the following order: (5') H2B25,35-H455,65-H375,85,95/H488-H2B105,11 5-H2A118-H3135,145/H2A145 (3') (the subscripts give approximate distance in nucleotides of the main histone contacts from the 5'-end). Hence, the histone tetramer (H3,H4)2 and two dimers (H2A-H2B) are arranged on double-stranded core DNA in a symmetrical and rather autonomous way: H2A/H3-(H2A-H2B)-(H3,H4)2-(H2B-H2A)-H3/H2A. The primary organization was found to be very similar in core particles isolated from repressed nuclei of sea urchin sperm and chicken erythrocytes, from active in replication and transcription nuclei of Drosophila embryos and yeast and from somatic cells of lily. These data show that (i) the core structure is highly conserved in evolution and (ii) the overall inactivation of chromatin does not affect the arrangement of histones along DNA and thus does not seem to be regulated on this level of the core structure.