[The role of chromatoid bodies and cytoskeleton for differentiation of rat spermatozoids].

The ultrastructural and immunocytochemical study of rat male germ cells on different developing stages has been made. The investigation of morphological changes of spermatogenic cells has demonstrated the presence of tight connections between chromatoid bodies (CBs) and other cell organelles, particularly with the nucleus and Golgi apparatus; has revealed the association of manchette noncentrosomal microtubules (MT) with spermatid perinuclear ring plasma membrane (PM) in the zone of the adhesion intercellular contact--zonula adhaerens (ZA). The comparison of the results obtained in this work with available literary data has given possibility to analyze expected pathways of noncentrosomal MT nucleation in the late spermatids.

[Specific properties and primary structure of BASP1 protein, initially detected in neuronal axonal terminals].

The BASP1 protein is one of the acidic (pI 4.3-4.6) acid-soluble brain proteins; it is predominant in growth cones and presynaptic regions of neurons.

[High plasmid pBR322 multimerization in Escherichia coli B].

In bacteria E. coli B (wild) plasmid pBR322 is present as a set of circular supercoiled multimers formed of up to 20 head-to-tail linked monomers. The highest degree of plasmid multimerization was achieved when the bacteria were grown in a mineral-glucose medium based on 0.

[HMG protein levels in cell nuclei with different proliferative and transcription activities].

It is shown that HMG1 and HMG2 proteins are present in the nuclei of the both actively proliferating and resting lymphocytes in the equally high amount. On the other hand, the same proteins are almost or even completely absent from the nuclei of all kinds of hepatocytes studied: nonproliferating hepatocytes from calf and rat liver and actively proliferating cells from rat regenerating liver and primary hepatoma. These results reveal a tissue specific distribution of HMG1 and HMG2 proteins and do not confirm the suggestions that HMG1 and HMG2 proteins are necessarily involved in chromatin replication or transcription.

[Low transfecting efficiency of phage lambda ring chromosomes and their fragments formed by membrane nucleases].

Transfection efficiency of a number of lambda DNA samples differing in ring to linear molecules ratio was determined. Graphic extrapolation to the zero content of linear molecules showed that efficiency of ring molecules did not exceed 5% of that of linear molecules. Probably, this difference is caused by more fast penetration of linear molecules into the cell and, therefore, by lower probability of their degradation by cell wall nucleases.

[Spontaneous transformation characteristics of Bacillus subtilis bacteria. I. The relatively low transforming activity of spontaneously released DNA for markers located close to the origin and termination points of chromosome replication].

Relative efficiencies of spontaneous Bacillus subtilis transformation for markers placed in different areas of the cell chromosome were studied. As donor of genetic material, an untransformable strain BD224 trpC2 thr5 rec4 was used during its early log-phase. It was found that for markers placed near points of origin and termination of the chromosome replication the relative transformation efficiencies are significantly lower than those in the case of transformation with DNA extracted from the same donor cells.

[Problem of chromosome formation in T-even phages].

Three basic versions for the formation of circularly permuted and terminally redundant chromosomes with rings, concatemers, or fragments as replicative intermediates were considered. Experimental results show that the chromosome of T-even phage can turn into 4-6 large fragments soon after it penetrates inside the Escherichia coli cell. The fragments are capable for autonomous replication and contribute their material to progeny phage chromosomes.

[Detailed model of semi-conservative DNA replication. Possible role of DNA-polymerase errors in fragmented copying of both matrix strands].

A model of semiconservative DNA synthesis is considered. The model is based on a suggestion that the synthesis proceeds in the course of one-directional stretching of both matrix strands through the replicase complex (replisome), or of one-directional movement of the replisome along the chromosome. Each nucleotide link of the matrix strand find itself successively in the section of RNA primer synthesis, in the section of DNA polymerase and in the control section of a proofreading 3' leads to 5' exonuclease.

[Infectivity of different forms of lambda bacteriophage DNA in transfection of calcinated Escherichia coli].

Infectivity of linear lambdaDNA molecules is proved to be about a hundred times higher in calcinated E. coli K12 (lambai434) than in E. coli K12(lambda-): the levels of transfection were 1-3-10(7) and 1-2-10(5) infective centers per 1 mug DNA, respectively.