Expression of the Artemia trachealess gene in the salt gland and epipod.

The Drosophila trachealess gene encodes a basic-helix-loop-helix-PAS transcription factor that controls the formation of the trachea and salivary duct. An ortholog of trachealess was identified in the brine shrimp, Artemia franciscana, and was shown to be highly conserved by sequence identity. Expression of Artemia trachealess was observed at two sites during development: the naupliar salt gland and the juvenile thoracic epipod. These two organs function at their respective times of development in osmoregulation, an important aspect of brine shrimp physiology. This extends the range of putative functions of trachealess to include formation of osmoregulatory, respiratory, and ductile organs.