Identification and differential expression of hepatopancreas microRNAs in red swamp crayfish fed with emodin diet

Using high-throughput Illumina Solexa system, the differential miRNA expressions from hepatopancreas in red swamp crayfish (Procambarus clarkii) fed with diets containing 0 (control) and 75 mg emodin kg−1 (trial) were identified, respectively. As a result, 13,335,928 raw reads from the control sample and 14,938,951 raw reads from the trial sample were obtained while 13,053,344 (98.77%) and 14,517,522 (98.34%) small RNA were identified, respectively. 106 mature miRNAs (belonging to 68 miRNA gene families) were identified. 35 miRNAs displayed significantly differential expressions between two libraries. Of these, comparing to the control library, 6 miRNAs were significantly up-regulated and 29 miRNAs were significantly down-regulated. Moreover, 5 novel miRNAs (2 from control sample, 3 from trial sample) and target genes were predicted. GO analysis suggested that these miRNAs might be involved in innate immune response, growth, metabolism, cellular process, biological regulation and stimulus response. Our knowledge from this study could contribute to a better understanding of the miRNAs roles in regulating innate immune response and the study of miRNA function in crayfish.