The two Cg-timp mRNAs expressed in oyster hemocytes are generated by two gene families and differentially expressed during ontogenesis.

We previously characterized a Crassostrea gigas tissue inhibitor of metalloproteinase (Cg-timp 1.3) with potential role in wound healing and defense mechanisms. Here we isolated a second cDNA (Cg-timp 1.1) encoding a protein that contains the characteristic signature of TIMP proteins. Sequence analysis of the two transcripts showed that they originate from two distinct genes. The two proteins, Cg-TIMP 1.1 and 1.3, are closely related and share 81% identity. Northern blot analysis of Cg-timp gene expression in adult oyster hemocytes indicated that the ratio between the two transcripts was constant from one oyster to another (Cg-timp 1.1 and 1.3 represent 32 and 68%, respectively). Conversely, during ontogenesis the expression pattern of the two Cg-timp genes was different. Indeed, Cg-timp 1.3 mRNAs were detected from the larval D stage whereas Cg-timp 1.1 transcripts were undetectable up to 22 days post-fertilization. The difference in expression pattern of the two Cg-timp genes may reveal distinct implications of these genes in the embryos and larvae developments.