Intron mobility results in rearrangement in mitochondrial DNAs of heterokaryon incompatible Aspergillus japonicus strains after protoplast fusion

Mitochondrial transmission was carried out under selective conditions betwe en incompatible Aspergillus japonicus strains always using an oligomycin-re sistant mitochondrial donor and selecting for recipient nuclei and oligomyc in-resistant mitochondria. All attempted intraspecific mitochondrial transm issions were successful, but the transmission between closely related A. ja ponicus and A. aculeatus failed. Under selection pressure, resistant progen y harbor the mitochondrial DNA (mtDNA) of the donor strain, which may remai n unchanged or may be modified by the introns of the recipient mitochondria l genome. Detailed analysis of a certain strain harboring rearranged mtDNA suggests that the mtDNA profiles of recombinant-like progeny are strongly i nfluenced by the characteristics and mobility of introns of both parental m tDNAs. Both intron loss and intron acquisition play a role in the rearrange ment of mtDNA. In certain parental combinations, a particular intron was lo st very frequently. (C) 2001 Academic Press.