I-R system of hybrid dysgenesis in Drosophila melanogaster: analysis of the mitochondrial DNA in reactive strains exhibiting different potentials forI factor transposition

In the I-R hybrid dysgenesis system, Drosophila melanogaster strains fall i nto two categories denoted inducer (I) and reactive (R). Among the reactive strains we can distinguish strains with weak, medium or strong reactivity levels. These levels are inherited in a complex way involving both chromoso mal and nonchromosomal determinants, the nonchromosomal determinant being m ainly maternally inherited. We were interested in determining the molecular basis of this maternal transmission. In this article we analyse the possib le implication of the mitochondrial DNA in the determination of the reactiv ity levels. The mtDNA was analysed in lines with very different reactivity levels with the aim of correlating sequence differences with reactivity lev els. The mtDNA was analysed by sequencing and restriction fragment length. No correlation was established between reactivity level and mtDNA sequence. This may favour the hypothesis that epigenetic changes would be responsibl e for the different reactivity levels and their transgenerational transmiss ion.