We have characterized the phenotypes of flies mutant for 3 EMS and 1 P element induced alleles of zpg .
Flies mutant for zpg are viable but sterile with very small gonads.
The mutant gonads contain stem cells and early germ line cells, based on characterization with known markers and anti-vasa staining. In zpg testes or ovaries, germline stem cells appear to divide but the early germ cells fail to differentiate, but rather, form small clusters and undergo apoptosis, as observed by staining with acridine orange. To understand the molecular and biochemical function of the zpg gene product, we are cloning zpg using the P-element tagged allele. The biochemical nature of the zpg gene product and its expression pattern should suggest how zpg acts to allow early germ cells to survive and differentiate.