IDENTIFICATION AND SPATIAL-DISTRIBUTION OF THE MESSENGER-RNA ENCODINGTHE GP49 COMPONENT OF THE GILTHEAD SEA BREAM, SPARUS-AURATA, EGG ENVELOPE

A cDNA encoding the precursor of one of the major components of gilthe ad sea bream, Sparus aurata, egg envelope has been cloned by reverse t ranscriptase polymerase chain reaction (RT-PCR) techniques. The clone was isolated starting from total RNA extracted from the liver of spawn ing female fish and estradiol-17 beta-treated male fish. Sequence anal ysis revealed that the cDNA encoded a protein of 405 aa corresponding to 49-kDa component (termed gp49), a glycoprotein belonging to the N-l inked type. The gp49 protein is homologous to the ZI-3 of medaka Oryzi as latipes, the mammalian ZPC and ZPC homologues of Xenopus laevis (xl ZPC) and carp Cyprinus carpio (ccZPC). In addition, the open reading f rame also encodes an additional aa sequence, the signal peptide, locat ed in the N terminal region of the protein. RT-PCR and in situ express ion analyses evidenced an organ-restricted pattern: the mRNA was detec ted only in liver of spawning female and estradiol-17 beta-treated mal e fish but not in other tissues. (C) 1998 Wiley-Liss, Inc.