Responses of thioredoxin 1 and thioredoxin-related protein 14 mRNAs to cadmium and copper stresses in Venerupis philippinarum

Thioredoxin (abbreviated as Trx) is an important ubiquitous disulfide reductase, which can protect organisms against various oxidative stresses. In the present study, thioredoxin 1 (named as VpTrx1) and thioredoxin-related protein (named as VpTrp14) were identified from Venerupis philippinarum, respectively. Similar to most Trx1s, VpTrx1 possessed all conserved features critical for the fundamental structure and function of Trx1s, such as the conserved catalytic residues (C-G-P-C), but lacked the other cysteine residues, while VpTrp14 contained the conserved motif (C-P-D-C). Quantitative Real-time PCR assay showed that VpTrx1 and VpTrp14 transcripts were distributed in a wide array of tissues most abundantly expressed in the hepatopancreas. The expression of VpTrp14 mRNA in the hepatopancreas was significantly up-regulated after exposure to 10 and 40 mu g/L Cd, while the VpTrx1 expression level was kept relatively constant. Both the expression levels of VpTrx1 and VpTrp14 in the hepatopancreas were induced after exposure to Cu, and increased to the peak value at 96 h under the 40 mu g/L Cu exposure. These results showed that VpTrp14 transcripts responded to metal stress more acutely than VpTrx1, and both Trxs responded to Cu stress more sensitively than Cd. Together, it was suggested that VpTrx1 and VpTrp14 perhaps played important roles in the antioxidant responses against metal stress in V. philippinarum. (C) 2011 Elsevier Inc. All rights reserved.