Differential expression of microRNAs in hemocytes from white shrimp Litopenaeus vannamei under copper stress.

MicroRNAs (miRNAs) are small noncoding RNAs that regulate diverse cellular processes, including organismal stress response, through posttranscriptional repression of gene transcripts. They are known to have antiviral functions in aquatic crustacean species, but little is known about the role of miRNAs against environmental stress caused by Cu, a common chemical contaminant in aquatic environment. We performed small RNA sequencing to characterize the differentially expressed microRNAs in Cu exposed shrimp. A total of 4524 known miRNAs and 73 novel miRNAs were significantly (P < .05) differentially expressed after Cu exposure. The peak size of miRNAs was 22 nt. Among them, 218 miRNAs were conserved across 115 species. The validation of 12 miRNAs by stem-loop quantitative RT-PCR were found to be coherent with the expression profile of deep sequencing data as evaluated with Pearson's correlation coefficient (r = 0.707). Target genes of these differentially expressed miRNAs related to immune defense, apoptosis, and xenobiotics metabolism also showed significant changes in expression under Cu stress. The present study provides the first characterization of L. vannamei miRNAs and some target genes expression in response to Cu stress, and the findings support the hypothesis that certain miRNAs along with their target genes might be essential in the intricate adaptive response regulation networks. Our current study will provide valuable information to take an insight into molecular mechanism of L. vannamei against environmental stress.