[Features of integration of recombinant cosmids, containing Aspergillus terreus DNA, in the Saccharomyces cerevisiae genome].

A genome clonotheque of 25-40 kb Sau3A fragments of Aspergillus terreus DNA was constructed in the episomal cosmid vector pES33 containing the ARG4 gene of yeast. 23 independently originated stable Arg+ transformants were selected after transformation of the cir0 yeast strain ESH-O with pooled cosmid molecules. Both genetic and Southern analysis showed that 39% of these stable transformants occurred due to recombination between DNA sequences from A. terreus and Saccharomyces cerevisiae chromosome XII which took place most likely in the regions of homology within the ribosomal clusters. The data present the first evidence of in vivo recombination between foreign sequences and their S. cerevisiae counterparts.