In Drosophila ovaries, germ-line stem cells (GSCs) reside in a specialised niche at the anterior of each germarium. GSCs divide asymmetrically, the anterior cell remaining in the niche as a GSC and the posterior cell differentiating into a cystoblast from which an egg will eventually develop. On p. 6625, Gilboa et al. report that Zero population growth (Zpg), a gap-junction protein, is required for both GSC differentiation and survival. They show that although GSCs lacking Zpg can divide, few germ cells become cystoblasts, as indicated by lack of synthesis of the Bag of marbles protein BamC, a cystoblast marker. Instead, the daughter cell destined to differentiate dies. The researchers propose that zpg acts in parallel to the genes bam and benign gonial cell neoplasm, which encode proteins that are needed for differentiation of the cystoblast, and also suggest that GSC differentiation into a cystoblast is gradual, occurring via an intermediate state.

© The Company of Biologists Limited 2003
2003