An autosomal gene in Drosophila melanogaster that is thought to regulate early germ cell development in both sexes. In the female, bam mutations produce ovarian tumors characterized by mitotically active stem cells which fail to produce cystoblast cells and their progeny, the interconnected cystocytes. In the male, bam mutations produce germ line cysts containing excessive numbers of primary and secondary spermatogonial cells which fail to differentiate. The bam gene encodes a novel protein which is found in the spectrosome (q.v.), the fusome (q.v.), and cytoplasm of cystocytes and spermatogonial cells. Fusomes in bam mutant females are structurally abnormal, leading to the suggestion that normal fusome biogenesis is essential for a switch from stem cell-like to cystoblast-like cell division. In males, bam gene product is thought to restrict the overproliferation of spermatogonial cells undergoing incomplete cytokinesis. See cystocyte divisions, spermatogonia.
Subjects: Genetics and Genomics.