A novel type of gene interaction in D. melanogaster.

The genes interact according to classical mechanisms, namely, complementation, modification, polymery, and epistasis, in the cells and organisms carrying these genes. Here we describe a novel type of gene interaction when the interacting genes reside in parents, whereas the interaction event takes place in their progenies lacking these genes. The conditional mutations in the D. melanogaster male X chromosome caused the "prohibition on producing daughters" in its offspring. The chromosomal rearrangements in chromosomes 2 and 3 of its female partner removed the prohibition. The phenomena of "prohibition" and "removal of prohibition" appeared as a parental effect in both the male and female. Both phenomena ensued from the presence of the studied mutations in parents rather than their unviable or survived progenies. Thus, the gene interaction when the genes themselves are absent at the site of interaction and during the interaction event takes place in drosophila.