Identification and characteristics of a novel gene, EJO1, in the Chinese mitten crab (Eriocheir japonica sinensis) ovary.

EJO1, a novel gene presumably involved in the ovary development of the Chinese mitten crab (Eriocheir japonica sinensis), was identified and characterized by suppression subtractive hybridization and cDNA macroarray analysis. EJO1 expression was 2.6-fold higher at stage III than at stage II during the ovary development of the mitten crab. EJO1 is 876 bp in length containing a 759 bp open reading frame which encodes a 252-amino-acid protein. Homology analysis showed that no sequence significantly matching EJO1 was found in SwissProt, so it was deduced as a novel gene (GenBank accession number: AY185917). The EJO1 protein is probably a secretion protein with a signal peptide of 17 amino acids. The pI/Mw deduced from the amino acid sequence was 6.18/28.18 kDa. Expression profile showed that EJO1 mRNA is highly expressed in the heart, intestine, and ovary of the crab, while there is little or no expression in muscle and hepatopancreas. The differential expression of EJO1 at the different developmental stages of the ovary was further confirmed by Northern blot analysis. In conclusion, EJO1 is a novel gene differentially expressed in the ovary of the Chinese mitten crab, which may play an important role in the ovary development.