Meeting Abstract

P1.87  Jan. 4  Na⁺/K⁺-ATPase gene expression during the ontogeny of the crayfish Astacus leptodactylus SERRANO, Laetitia; TOWLE, David/W*; CHARMANTIER, Guy; SPANINGS-PIERROT, Celine; Auburn Univ., Alabama; MDIBL, Maine; Univ. Montpellier II, France; Univ. Montpellier II, France serrala@auburn.edu

The crayfish Astacus leptodactylus is fully adapted to freshwater where it spends its entire life cycle despite the osmotic stress. It undergoes direct embryonic development, a feature of most FW crustaceans: embryonic and post-embryonic developments are included in eggs attached to the pleopods of the female and juveniles are directly exposed to the external medium at hatch. By providing the major driving force for ion transport, the Na⁺/K⁺-ATPase plays an essential role in ionoregulatory processes. We investigated the mRNA expression of Na⁺/K⁺-ATPase α-subunit and β-actin, a putative housekeeping gene, during crayfish ontogeny using real-time quantitative PCR. A partial nucleotide sequence of the open reading frame region coding for the Na⁺/K⁺-ATPase α-subunit was obtained from total embryos, juveniles and adult gills. This sequence showed up to 95% and 69% identity with those from other invertebrates and vertebrates, respectively. The Na⁺/K⁺-ATPase α-subunit gene was expressed in all studied stages from metanauplius to juvenile. A first peak of expression was observed in embryos at 25% of the development period and a second one in embryos just before hatching, continuing to increase in the freshly hatched juveniles. Modest changes of β-actin expression were observed through embryonic and early post-embryonic development. The Na⁺/K⁺-ATPase expression profile during ontogeny is time-correlated with the occurrence of other features linked to hyperosmoregulation processes (i.e. excretory antennal glands ontogeny and gill ionocytes differentiation) and therefore involved in freshwater adaptation. Supported by doctoral fellowship from the French Ministry of Education and Research to LS.