| Abstrakt: |
Yeast mitochondrial markers of the resistance to antibiotics (erythromycin, neomycin and monomycin) were used to study mitochondrial recombination in bifactorial crosses both in cis and trans configurations of markers. Our strains of Saccharomyces cerevisiae are isochromosomal and isomitochondrial due to all of them have originated from one haploid pace XII of Sacch. cerevisiae. The following parameters of mitochondrial recombination were examined in random samples of zygotic diploid daughter colonies; a) the asymmetric transmission of parental classes; b) the frequency of recombination; c) the polarity of recombination; d) the effect of cell mating type on these parameters in reciprocal crosses. The data obtained suggest the following features of mitochondrial recombination: a) The distribution of both classes as parental and recombinant is unequal: there is asymmetrical transmission (0,22-1,72) and some polarity of recombination (up to 4,0). b) The effect of cell mating type on asymmetrical transmission was established only is some crosses in trans-configuration of mitochondrial markers. In cis-configuration crosses such effect was not observed. c) Different mitochondrial mutations influenced on all the above listed parameters (asymmetrical transmission of parental classes, the frequency and the polarity of recombination). Some correlation between the high level of asymmetrical transmission of parental classes and the low frequency of recombination was found in crosses with NR and MR mutants. The existence of several different loci among ER, NR and MR mutants is suggested on the basis of the data on the recombination frequency. |
