A small heat shock protein (sHSP) from Sinonovacula constricta against heavy metals stresses.

Small heat shock proteins (sHSPs) are ATP-independent molecular chaperones and involved into many physiological and stress processes. In the present study, the full-length cDNA of sHSP was cloned from razor clam Sinonovacula constricta (denoted as ScsHSP) through cDNA library and PCR approaches. Some feature motifs like the typical α-crystalline domain with six beta strands, three susceptible phosphorylation serines (S15, S78, and S82) were conserved in the deduce amino acid of ScsHSP. Tissue distribution analysis of the ScsHSP revealed that the mRNA transcripts of ScsHSP were constitutively expressed in all examined tissues with the highest expressions in the haemocytes. The temporal expression of ScsHSP in gill and haemocytes after PbCl2 and CdCl2 exposure were recorded by qPCR. The suppressed expression patterns were detected in CdCl2 stress at both tissues, and the minimum expression were detected at 36 h with 0.58-fold decrease in haemocytes and 0.30-fold in gill compared to each control group. During the PbCl2 exposure experiment, the expression level of ScsHSP increased significantly with larger amplitude in haemocytes. As time progressed, the mRNA transcripts of ScsHSP recovered almost to the original level at 36 h. All our results indicated that ScsHSP was involved into mediating environmental pollutants exposure and considered to be a promising candidate bio-mark for heavy metals monitoring.