In situ hybridization analyses of Na, K-ATPase α-subunit expression during early larval development of Artemia franciscana

Abstract

The spatial pattern of expression of the mRNA encoded by the Na,K-ATPase α-subunit cDNA clone pArATNa136 was determined by in situ hybridization of first, second, and third instar Artemia franciscana larvae. This mRNA was expressed at high levels in the salt gland, the antennal gland, and the end of the midgut, which are the three main osmoregulatory organs in Artemia at these stages of development. The pattern of expression was similar at the three stages of development analyzed, although the level of expression increased during development, especially in the salt and antennal glands. The expression of the mRNA coding for another Na,K-ATPase α-subunit isoform, the proposed α2-isoform, was also determined and was shown to be limited to the salt gland. These results suggest that the done pArATNa136 codes for the biochemically defined α1-isoform of the Na,K-ATPase α-subunit and reinforce the importance of this isoform in osmoregulation at the three larval stages studied. The α2-isoform may also be involved in osmoregulation during the first stages of larval development.