Expression of a Na, K-ATPase beta3 subunit during development of the zebrafish central nervous system

Zebrafish beta3, a full length cDNA clone encoding a zebrafish Na,K‐ATPase beta subunit, was isolated. The protein shares highest homology with the beta3 subunits of amphibians and mammals, slightly less homology with the beta2 subunits, and is distinct from the betal subunits. The fish beta subunit co‐assembled with alpha subunits to form Na,K‐ATPase enzymes when expressed in Xenopus oocytes. Embryonic expression was first detected by whole‐mount in situ hybridization between 8–12 hr post‐fertilization (hpf) in the head mesoderm. Subsequently, and up to 24 hpf, the mRNA was confined to four dorsal domains in the anterior neural tube. After a transient downregulation during the second day, expression was again conspicuous in the nervous system of 3‐day‐old larvae. Based on its distribution pattern, the fish beta subunit could be involved in setting up regional identities in the developing fish CNS and in the differentiation of distinct cell types. © 1996 Wiley‐Liss, Inc.