Induction of HSP70 gene expression in freshwater bivalve, Anodonta cygnea, caused by exposing to CuO-NPs

Anodonta cygnea is considered as a suitable species in evaluating the pollution of aquatic ecosystems because of the low resistance to changes in environmental conditions. Nowadays, due to the wide application of nanomaterials in different industries, the negative effect of these materials on aquatic life is of great concern. In the present study, the effect of copper oxide nanoparticles (II) (CuO-NPs) on HSP70 gene expression was evaluated in A. cygnea. For this purpose, the mussels were exposed to the concentrations of 0 (control), 0.25, 2.5 and 25ppm of CuO-NPs during 12 days. To analyze the changes in HSP70 gene expression, the sequence of this gene was determined in this species. In this regard, a fragment of 540 nucleotide coding HSP70 was cloned. The nucleotide sequence of HSP70 in A. cygnea contained 19.8, 30.7, 26.7 and 22.9 percent of A, C, G and T, respectively. The results indicated that exposing to CuO-NPs induced HSP70 gene expression in both tissues of foot and gill. Hereof, there was no significant difference (P>0.05) in gene expression level of HSP70 among foot and gill tissues. Also, the gene expression level in the studied tissues increased with increasing exposure time up to 8 days while it showed decrease over the time up to 12th day (P≤0.05). In conclusion, the HSP70 gene in A. cygnea showed higher level of GC nucleotides in comparison to the other studied species and the expression level of this gene increases under exposing to CuO-NPs so that this increase is dependent on the concentration and time.