Genetics of inbred Drosophila melanogaster. XXII. Cytoplasmic influence on recombination.

To examine the possible influence of various sources of cytoplasms on recombination in the major part of the X-chromosome in Drosophila melanogaster, tests were performed in intra- and inter-line crosses. Two to six sister lines of various types were included. It was shown that cytoplasms of various sources could have different effects in the distal y-cx region but not in the mid (cx-v) or the sub-proximal (v-f) regions in both intra- and inter-line crosses. There were no diversities between sister-lines that had been separated for over 100 generations. Tests of two sets of sister-lines with the same source of cytoplasm in which different genomes had been introduced confirmed the earlier finding that there is an interaction of chromosomal and cytoplasmic influences on recombination. It is shown that changes in one extrachromosomal element (R-elements) had no demonstrable consequences on the effect on recombination. The necessity to consider cytoplasmic-bound variability is stressed.