Heterochromatic recombination in germ cells of Drosophila melanogaster females.

Heterochromatic recombination in germ cells was found to occur in females of Drosophila melanogaster having a specific genotype. Results of the present study can be summarized as follows: (1) The frequency of heterochromatic recombination decreases consistently and markedly as the female ages. (2) The female that induces heterochromatic recombination is associated with reduced number of progeny when she is young, but as she gets older, the number of progeny increases, approaching that of the normal female. The reduction in the number of progeny is due to unhatchability of eggs produced, not to reduced egg laying. (3) Cytoplasmic factors affect the above two traits. These traits seem to be due to interaction between chromosomal and cytoplasmic elements. (4) These traits are not expressed in males. (5) The increase in recombination frequency seems to be limited to the centric heterochromatin.--It is suggested that heterochromatic recombination is one of the traits associated with the I-R system of hybrid dysgenesis in D. melanogaster.