DDX6 belongs to a family of DEAD-box RNA helicases, which are RNA splicing proteins that ensure the correct folding and structure of mature RNA. Gametogenesis requires the participation of many kinds of RNA. To explore its functions during Eriocheir sinensis gametogenesis, we cloned a full-length DDX6 cDNA sequence from E. sinensis (Es-DDX6) which contains a 1536-nucleotide open reading frame encoding a 512-amino acid protein. Multiple sequence alignments showed that Es-DDX6 has ten conservative DEAD-box family motifs.
A novel collagenolytic serine protease (CLSP) was cloned from the hemocytes of the Chinese mitten crab Eriocheir sinensis (Es-CLSP). The full-length cDNA of Es-CLSP contains 990 nucleotides. It encodes a 270-amino acid-long peptide with the mature peptide containing 221 amino acids. It contains the conserved catalytic triad (H, D, and S). Similarity analysis shows that Es-CLSP shares high identity with CLSPs from the fiddler crab Uca pugilator. Es-CLSP mRNA expression in E.
A cytosolic manganese superoxide dismutase gene (Es-cMnSOD) was cloned from the Chinese mitten crab Eriocheir sinensis, using reverse transcription-polymerase chain reaction and the rapid amplification of cDNA ends. The open reading frame of Es-cMnSOD is 867 bp in length and encodes a 288-amino acid protein without a signal peptide. The calculated molecular mass of the translated protein of Es-cMnSOD is 31.43 kDa, with an estimated isoelectric point of 6.30.
Eriocheir sinensis is a euryhaline crab migrating from sea to freshwater habitats during the juvenile stage. We used quantitative real-time polymerase chain reaction (qRT-PCR) to investigate the gene expression profile of Na+-K+-ATPase, Hsp70 (heat shock protein 70) and Hsp90 in megalopa exposed to salinities of 0, 2, 5, 10, and 15 parts per thousand.