Studies On The MiRNAs Of The Larvae And The Nymphs

Trilophidia annulata, Shirakiacris shirakii, Tetrix japonica are belong to Oedipodidae, Catantopidae, Tetrigoidae in Orthoptera, respectively. They are widely distributed in China. MicroRNAs are a class of non-coding small RNA that regulate gene expression by promoting translational repression or degradation of target mRNAs through binding to their 3’untranslated regions(3’UTR). The research about miRNA has become popular in recent years. However, the study about Othorptera insects is mainly focused on the aspects of morphology, population genetic diversity, mitochondrial genome and phylogeny, miRNA in this three species have not been reported to date.In this study, the miRNA transcriptomes of nymphs and adults were profiled using Illumina HiSeqTM 2000 high-throughput sequencing platform, based on the filtering of the raw reads, the bioinformatics was used to identify the conserved known miRNA and novel potential miRNA candidates. In order to further understanding the role of miRNAs during the different stage of growth and development of locust,we analysised the miRNA expression pattern and predicted the target genes of differential expressed miRNA. The main points are indicated as follows:(1)A total of 206 and 203 known miRNAs were identified in the adults and nymphs libraries of S.shirakii, with 951,089 and 637,545 reads, respectively. After grouping the identical sequences, a total of 222 miRNAs were obtained from both libraries, and 187 within 222(84.23%) conserved miRNAs were co-expressed in both libraries,19(8.56%) adults-specific and 16(7.21%) nymphs-specific miRNAs were identified.A total of 201 and 200 known miRNAs were identified in the adults and nymphs libraries of T.annulata, with 1,254,897 and 269,551 reads, respectively. After grouping the identical sequences, a total of 215 miRNAs were obtained from both libraries, and 186 within 215(86.51%) conserved miRNAs were co-expressed in both libraries, 15(6.98%) adults-specific and 14(6.51%) nymphs-specific miRNAs were identified.A total of 251 and 239 known miRNAs were identified in the adults and nymphs libraries of T. japonica, with 1,335,438 and 960,861 reads, respectively. After grouping the identical sequences, a total of 258 miRNAs were obtained from both libraries, and 232 within 258(89.92%) conserved miRNAs were co-expressed in both libraries, 19(7.36%) adults-specific and 7(2.71%) nymphs-specific miRNAs were identified.A total of 200 conserved miRNAs were co-expressed in six libraries.(2) A total of 56 and 38 novel miRNAs were predicted in the adults and nymphs libraries of S.shirakii, respectively. A total of 117 and 211 novel miRNAs were predicted in the adults and nymphs libraries of T.annulata, respectively. A total of 7 and 8 novel miRNAs were predicted in the adults and nymphs libraries of T. japonica, respectively.(3) we analysised the miRNA expression pattern of adults and nymphs libraries, there are 51 conserved miRNAs were siganificantly differentially expressed between adults and nymphs libraries of S.shirakii,114 conserved miRNAs were significantly differentially expressed between adults and nymphs libraries of T.annulata, and 54 conserved miRNAs were significantly differentially expressed between adults and nymphs libraries of T. japonica. This findings contribute to our understanding of the miRNAs involved in the development of locust.(4)The putative target sites of miRNAs were predicted to provide some molecular insight into their function.A total of 53429 unigenes were predicted as putative target genes for 51 differentially expressed miRNAs of S.shirakii. A total of 71699 unigenes were predicted as putative target genes for 114 differentially expressed miRNAs of T.annulata. A total of 41004 unigenes were predicted as putative target genes for 54 differentially expressed miRNAs of T. japonica.(5)The GO enrichment analysis of differentially expressed miRNAs shows that most of the target genes were termed as metabolic process. And there are hundreds of target genes were involved in reproduction biological process, nervous system development, respiratory system development, skeletal muscle fiber development.The results suggested that various aspects of the growth and development of locust is regulated by miRNA,and the evidence based on the extensive involvement of miRNAs demonstrated that the regulatory role of miRNA.is very important.According to KEGG function annotations, most of the predicted target genes were involved in cellular metabolism, signaling transduction and RNA activity, the key protease or protein factor in this pathway was regulated by miRNA, declare that miRNAs formed a complex regulatory network in insects.