[DNA fingerprinting in horses]. / DNA fingerprinting u koní.

Using a multilocus DNA probe, individual - specific hybridization patterns, the so-called DNA fingerprints (TAB) were determined in six horse families by the DNA fingerprinting method. The probe with evolutionally preserved nucleotide sequence from bacteriophage M13 determines hypervariable regions placed in genomic minisatellite DNA. The use of this probe permits an identification of an individual and execution of paternity relationships with a probability over 99.99 per cent.

A transformation-competent recombinant between v-src and Rous-associated virus RAV-1.

The LTR, v-src, LTR provirus, which arose by the reverse transcription and integration of src mRNA in the H-19 hamster tumor, has been successfully rescued by fusion with chicken fibroblasts infected with Rous-associated virus RAV-1. One rescued virus, E6, acquired 1 kilobase of the 5' end of the gag gene structure. Recombination took place in the region of 15-nucleotide homology exactly between v-src exon (position 7054) and gag (position 1417). This recombination resulted in the alteration of src splice acceptor site sequences, but this site is maintained as a functional splice acceptor site. The nucleotide structure of the long terminal repeat of recombinant E6 virus suggests that it arose by the intermolecular jump of reverse transcription from RAV-1 to src mRNA and then the switch of templates between already depicted regions of homology. The second jump of reverse transcription was apparently an intramolecular event. The acquisition of 1 kilobase of the 5' gag by E6 resulted in maintaining the balance of unspliced and spliced E6 RNAs and assured the replication advantage of rescued E6 virus over rescued F6 virus, the genome of which corresponds to that present in ancestral H-19 cells.

Structural analysis of proviruses in additional hamster tumour cell lines transformed by provirus II rescued from XC cells and definition of a new cell line harbouring amplified proviruses.

Additional 18 Syrian hamster tumour cell lines induced independently with the virus rescued from XC cells (provirus type II) have been analysed by restriction mapping. Taking into account the already published results of an analysis of other six tumour cell lines, altogether 24 tumour cell lines were characterized. In 62.5% of these lines a complete proviral unit has been integrated; 20.8% of the lines harbour altered proviral structures where the 3' end of the gag gene and the entire pol gene had been deleted; 8.3% of the lines carry both such a deleted provirus and a complete provirus. Apart from the already published cryptic provirus found in H-19 cells, no such provirus has been found in another cell line. Therefore the appearance of the cryptic provirus represents an infrequent event (4.16%). Similarly, the significant amplification of proviruses accompanied with a rearrangement in the env gene was found only in one tumour cell line. H-42, in the genome of which five proviral units are accommodated. The probable arrangement of amplified proviruses and the mechanism of their genesis are discussed.

Restriction analysis of additional "non-producing" cell clones obtained after transformation of Japanese quail fibroblasts with viruses rescued from cryptovirogenic H-19 cells.

The proviral structure of two transforming viruses rescued from cryptovirogenic H-19 hamster cells harbouring the LTR, v-src, LTR proviral structure was analysed by restriction mapping. It was established that the rescued G8 virus keeps the same restriction pattern as that observed in the cryptic H-19 provirus and that it is integrated into the cell genome at a different position characteristic of each "non-producing" (NP) cell clone. In these features it corresponds to the previously described F6 rescued virus. In studying the E6 rescued virus we found again that it is integrated at a position characteristic of the NP cell line studied. Using a series of restriction enzymes it was specified that the E6 proviral unit acquired at least 0.25 kb from the left part of the gag gene and 0.85 kb of an unidentified DNA. Because this DNA structure was not digested with the enzymes employed that cut in RSV provirus and did not hybridize with the viral gene probes, it might be of cellular origin. The recombinational events involved in E6 virus genesis, the nature of an additional DNA structure, and the functional significance of the acquired part of the gag gene are discussed.

Characterization of transforming viruses rescued from a hamster tumour cell line harbouring the v-src gene flanked by long terminal repeats.

The organization of proviruses derived from infecting transforming viruses rescued from hamster tumour cells was studied. Southern blot analysis indicated that the provirus from the F6 cell line was organized as long terminal repeat (LTR)-src-LTR, and S1 mapping experiments suggested that it was probably derived by reverse transcription of src mRNA followed by integration. In the E6 cell line, the provirus unit was arranged as LTR-delta gag-src-LTR, indicating a recombination event between the rescued transforming virus and the helper virus. These results suggest that transforming defective viruses containing only the src gene can be rescued from nonpermissive mammalian cells.