Mitochondrial inheritance in Schistosoma mansoni: Mitochondrial variable number tandem repeat mutation produces noise on top of the signal

The Schistosoma mansoni mitochondrial genome contains tandemly arrayed copi es of a 62-base repeat motif The tandem array is highly polymorphic with re spect to number of repeats and commonly exhibits heteroplasmy. This study s hows that a very high rate of mutation rapidly produces new repeat lengths (new haplotypes) for this mitochondrial variable number tandem repeat. A ma ternal inheritance pattern is also demonstrated for this repeat sequence, w hile the high mutation rate causes some offspring to exhibit nonmaternal ha plotypes. Frequent generation of new haplotypes can be observed within samp les of clonal cohorts taken from monomiracidial snail infections. These sam e clonal cercarial groups, when crossed, produce F-I generations that exhib it the maternal set of haplotypes, across all individuals, with the frequen t addition of new mutant haplotypes. In each of 2 crosses, a subset of the recently arisen haplotypes match paternal haplotypes by chance (30.4% and 1 8.8%), thus giving the false appearance of partial paternal inheritance of mitochondria.