[Single-stranded DNA from viruses, prokaryotes and eukaryotes]

The review presents the results of investigations of single-stranded DNAs of viruses, bacteria and cells of higher organisms. Methods of revealing, isolating and analysis of these DNAs are presented. A large variety of single-stranded DNA containing genomes of plant and animal viruses was revealed. Attention is drawn to the integration and replication of viral genomes. Results of SV40 integration during the first two days after infection of Chinese hamster cells are shown. Results of studying multi-copy single-stranded DNA in bacterial cells were analysed. In separate sections, the replication of plasmid single-stranded DNA was studied as well as the problem of plasmid stability in cells. Advances in bacteria transformation studies are stated. Data of single-stranded DNA investigation in cells of higher organisms are mainly presented on the example of early embryos. Data on the analysis of gene hypersensitivity to nuclease S1 are given. A table of proteins destabilizing and unweaving single-stranded DNA and a classification table of proteins bound with single-stranded DNA according to their functional significance are presented. It is stated that the problem of single-stranded DNA significance in cells remains open, although some results have been achieved.