The novel gene, mtre-1 , is expressed downstream of MAB-3 and DMD-3 in the male tail tip at the termination of male tail tip retraction.

The development of the adult male tail involves an extensive remodeling during the last larval stage where the pointed tail of the L4 male is converted into the blunt-ended adult tail with its collection of mechano-sensitive rays. The first step in this remodeling is the retraction of the four hypodermal cells of the tail tip to generate the blunt-ended tail. Male tail tip retraction is an excellent model for characterizing how upstream regulatory networks interact with the downstream cell biological effectors that drive morphogenetic changes in all animals. Previously, we've shown that two DM-domain transcription factors, MAB-3 and DMD-3 , are central regulators of male tail tip retraction. Using a microarray-based approach we have identified ~400 genes that are more highly expressed in the L4 male tail tip relative to the hermaphrodite L4 tail tip. The uncharacterized gene , which we've named , was highly over-represented in the male tail tip vs. the hermaphrodite tail tip and was under-represented in mutant male tail tips vs. wild-type male tail tips. A transcriptional reporter for shows clear expression in the male tail tip cells for a short period (~3 hours) at the end of retraction. This expression is dependent on the activity of MAB-3 and DMD-3 , since expression is reduced in single mutant males and absent in mutant males. Finally, males homozygous for a putative null allele of display a phenotypically wild-type adult male tail, indicating that is not essential for male tail morphogenesis.