Abstract
The vasa gene (vas) is essential for germline development in Drosophila melanogaster. Zygotic vas is expressed in pole cells earlier than any other pole cell-expressing genes thus far identified, and VAS protein is continuously present in germline cells throughout development. Here, we report the identification of a regulatory region that directs germline-specific vas expression. A genomic fragment containing the vas locus was linked to enhanced green fluorescent protein (egfp)-vas fusion gene, and the resulting gene was introduced into fly genome. Developmental vas expression was assessed by monitoring the expression of EGFP-VAS in these transformants. The spatio-temporal expression pattern of EGFP-VAS is essentially identical to that of endogenous VAS throughout germline development. By dissecting the vas promoter, we identified a 40-bp regulatory element, which is necessary and sufficient for germline-specific expression during oogenesis. This region interacts specifically with ovarian protein(s). Furthermore, this region is also required for vas expression in pole cells during embryogenesis. These results suggest that a similar mechanism regulates vas expression both in oogenesis and embryogenesis.
