Identification and comparative analysis of the Pseudosciaena crocea microRNA transcriptome response to poly(I:C) infection using a deep sequencing approach

Two sRNA libraries with or without poly(I:C) infection of large yellow croaker Pseudosciaena crocea were constructed and sequenced using the high-throughput Illumina/Solexa deep sequencing technology. The high-throughput sequencing pipeline yielded 163,79,272 and 217,07,070 raw reads corresponding to 132,27,594 and 206,86,409 clean reads for the normal and infected libraries, respectively. Bioinfromatic analysis identified 534 miRNAs, of which, 158 miRNAs were known in miRBase 20.0 and the remaining 376 were not found homology to any known metazoan miRNAs, suggesting a possible species-specificity. We analyzed the significance of differently expressed miRNAs between two libraries using pairwise comparison. There was significant differential expression of 112 miRNAs (p < 0.001) between two libraries. Thereinto, a number of known miRNAs were identified immune-related. Real-time quantitative PCR experiments (RT-qPCR) were preformed for 6 miRNAs of the two samples, and agreement was found between the sequencing and RT-qPCR data. To our knowledge, this is the first comprehensive study of miRNAs in P. crocea and of expression analysis of P. crocea miRNAs in response to poly(I:C) infection, and many miRNAs were differentially regulated under normal and infection conditions. These findings deepened our understanding of the role of miRNAs in the intricate hostʹs immune system, and should be useful to develop new control strategies for host immune defense against various foreign infection in P. crocea.