Systematic identification of seven ribosomal protein genes in bighead carp and their expression in response to microcystin-LR.

Microcystin-LR (MCLR) is one of the most toxic cyanotoxins produced in algal blooms. The toxic effects of MCLR on the expression of some organelles genes (mitochondrion, endoplasmic reticulum, and cytoskeleton etc) have been widely investigated, but little is known how it impacts on the expression of ribosomal genes. In this study we identified seven ribosomal protein genes RPS6, RPS12, RPS24, RPS27a, RPL12, RPL27 and RPL29 in bighead carp (Aristichthys nobilis), whose expression was regulated by MCLR. The amino acid sequences of those 7 genes shared more than 90% identity with corresponding sequences from zebrafish, and were well conserved throughout evolution. The 3D structure prediction showed that the structures of these ribosomal proteins were conserved, but had species specificity. Q-PCR analysis revealed that expression of seven genes changed dramatically at 3 hr, then went back to a moderate change- level at 24 hr in almost all tested tissues (liver, kidney, intestine, heart, spleen and gill) post MCLR injection, but in brain expression of the seven genes stayed same as the normal level. This study will help us to know not only about the evolution and functions of ribosomal proteins in anti-MCLR response in bighead carp, but also about the MCLR toxicity and its impact on aquaculture and human health.