AN APPROACH TO IDENTIFICATION OF HUMAN DNA REGIONS ACTIVE IN RECOMBINATION

A new DNA fragment from the human chromosome 3 was studied. Fluorescen ce in situ hybridization showed that this fragment is located mainly i n the unstable regions of the chromosome. The known repeated elements in the fragment were rearranged, it contained matrix attachment region s (MAR) and numerous sequences known to be associated with recombinati on sites. More than 60% of the fragment was composed of nonrandomly di stributed direct repeats. The distribution of direct repeats suggested their origin from unequal recombination of homologous chromosomal fra gments. The DNA structure and distribution of direct repeats are suppo sed to be related with the propensity to recombination within and betw een the chromosomes.