[en] Amino Acid Sequence ; Animals ; Artemia/*genetics/metabolism ; Base Sequence ; Blotting, Southern ; *Caenorhabditis elegans Proteins ; DNA Restriction Enzymes/metabolism ; *Gene Expression ; Homeodomain Proteins/*genetics/*metabolism ; In Situ Hybridization ; Molecular Sequence Data ; Reverse Transcriptase Polymerase Chain Reaction ; Salt Gland/*metabolism ; Time Factors
[en] We characterized the first POU-homeoprotein in a crustacean (designated APH-1 for Artemia POU-Homeoprotein, EMBL Y15070). The amino acid sequence of the APH-1 POU-domain is identical, except for two residues, to that of the two class III POU proteins Cf1-a (Drosophila) and POU-M1 (Bombyx mori). Southern blot analysis suggests that crustaceans have only one class III POU gene. RT-PCR and whole-mount in situ hybridization show that APH-1 mRNA is present in larvae specifically in the salt gland, an organ which is involved in osmoregulation, and disappears in the adult.