Molecular analysis of a major soluble egg protein in the scleractinian coral Favites chinensis

Soluble proteins were extracted from eggs of the scleractinian coral Favites chinensis, and analyzed using SDS-polyacrylamide gel electrophoresis. Two major proteins, named FcEP-1 and 2, were detected, and two partial amino acid sequences of FcEP-1 were determined. A cDNA encoding FcEP-1 was identified, using reverse transcription PCR with degenerate oligonucleotide primers designed based on the amino acid sequences, and rapid amplification of cDNA ends. Upon translation of the cDNA, FcEP-1 was predicted to consist of 648 amino acids, and the protein sequence exhibited similarity to vertebrate and invertebrate vitellogenins. FcEP-1 transcripts were already present approximately 6 months before spawning, when the size of oocytes was approximately 1/60 of the mature egg, and could be detected throughout the vitellogenic period. These observations suggest that detection of FcEP-1 transcripts may be useful to monitor the vitellogenic activity in F. chinensis.