Sporulation in Diploid Transformants of Saccharomyces cerevisiae Obtained by Illegitimate Integration of Single-stranded DNA
Krešimir Gjuračić1, Zoran Zgaga2*
1PLIVA Research Institute, Prilaz baruna Filipovića 25, 10000 Zagreb, Croatia
2Laboratory of Biology and Microbial Genetics, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
Received January 29, 1998
Accepted May 8, 1998
Saccharomyces cerevisiae, illegitimate recombination, sporulation
DNA sequence analysis and chromosomal polymorphism of natural and industrial yeast strains reveal important role of illegitimate recombination in the evolution of the yeast genome. The resulting genetic changes can be brought to the homozygous state by sporulation and mating between haploid progeny. In this work we compared sporulation of diploid transformants obtained by illegitimate integration of heterologous single-stranded (ss) DNA and transformants obtained with double-stranded (ds) plasmid that replicates autonomously in the yeast cell. The transformants that contained exogenous DNA integrated by illegitimate recombination had loiver efficiency of sporulation, but the spore viability was decreased from 80% to 65% only among preselected fraction of transformants. Some of the surviving haploids contained transforming DNA integrated in their genome. Possible mechanisms that led to the decrease in sporulation efficiency and spore viability in transformants obtained by illegitimate integration of foreign DNA into the yeast genome are discussed.