GENETIC IMPROVEMENT OF JAPANESE BLACK CATTLE BY USING SINGLE LOCUS VNTR MARKERS.

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Toward efficient improvements of Japanese Black cattle, we made a plan to introduce marker assisted selection procedures. DNA markers are useful tools for the purpose. However, almost all DNA markers now available are dinucleotide repeats. The analysis of dinucleotide erpeats loci requires a special expensive apparatus and high running costs. Therefore, we are planned cloning of tri or tetra nucleotide repeats loci and/or more longer minisatellite loci. Using bovine genomic libray, we had picked up more than 20 clones of tetra nucleotide repeats loci using (GGAT) _4 as a probe. These clones contained (GGAT) _n sequence, but showed incomplete repeats less than 5 repeats, showing no length variation. For (GTG) repeat, we get one clone which is preferable for DNA markers ; heterozygosity of the loci is more than 87% and the polymorphism is easily detectable by using conventional agarose gel electrophoresis. On the other hand, cloning of microsatellite using VNTR 33.15 as a probe, we also obtained 20 positive clones. Employing Southern hybridization technology, we get a few clone of polymorphic.