Sequence comprising Tag:degron(AID) sequence followed by EGFP has been inserted at the C-terminal end of the endogenous vas coding sequence. The presence of the Tag:degron(AID) tag allows the vas protein produced to be conditionally depleted using the auxin-inducible degradation system, while the EGFP tag allows the protein to be detected in vivo. A loxP cassette containing the Disc\RFP3xP3.cUa marker has also been introduced downstream of the vas 3'UTR.