Progeny from kar1 ? KAR1 crosses in Saccharomyces cerevisiae were isolated by selection for a mitochondrial marker from each parent. Haploid progeny (heteroplasmons, cytoductants) were obtained at high frequency because of thekar mutation and were identified by replication of progeny colonies to media differentiating on the basis of chromosomal markers. In some of the crosses nuclei of both parental types were found among the progeny, although the KAR1 nuclei were in majority. In crosses where only one parent contained the plasmid 2-micron DNA, all progeny inheriting the nucleus from that parent also had the plasmid, whereas only about 25?50% of the progeny with the other nucleus had the plasmid. In crosses where the size of 2-micron DNA of the parents was different, the haploid progeny had a plasmid size identical to that of the parent from which it had received its nucleus. On the basis of these observations we suggest a nuclear location of 2-micron DNA. We propose that one or a few copies of the plasmid are frequently transferred from one nucleus to another in kar1 mediated transient heterokaryons.

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Journal Article

Authors

Kielland-Brandt MC, Wilken B, Holmberg S, Petersen JGL, Nilsson-Tillgren T

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