Expression Analysis Of Ncrnas In The Silkgland Of Domesticated Silkworm Bombyx Mori

Abstrsct: A large number of non-coding RNA(ncRNA) were existed in the genome of both prokaryotes and eukaryotes. Among which, small ncRNAs like microRNA and siRNAs have been widely studied, accumulating evidences show that they play important and diverse roles in gene regulation, protein synthesis, chromatin modification et al.Silkworm(Bombyx mori)is the model insect of the order Lepidoptera, with considerable economic importance. The silkgland is the most powerful organ for protein biosynthesis during a short period. Many researches has been focus on the protein-coding genes of silkgland, but researches on the regulation of non-protein coding RNAs were few.In our laboratory, we constructed a cDNA library of small RNAs with lengths of 50-500nt in silkworm Bombyx mori, and identified 189 novel, small non-messenger RNA candidates. Further researches indicated that 40 ncRNAs showed significantly alternative expression during silkworm development or across specific stage transitions. In this study, we analysed the expression of these 40 ncRNA in different tissues of the fifth instar larva in silkworm, and found 6 ncRNAs accumulated much more in silkgland than other tissues. The function of these ncRNAs were further analysed. The main results were as following.With Northern blot method, the expression of the 40 ncRNAs which showed significantly alternative expression during silkworm development were analysed, results showed that 6 ncRNA (Bm-18,Bm-51,Bm-86,Bm-101,Bm-152,Bm-159) accumulated more in silkgland.The expression of host or up-down stream genes were analysed in different tissues of the fifth instar larva in silkworm, result showed that Bm-86 exhibiting negative correlation with its host gene BGIBMGA007469-T in the silkgland, while Bm-152 also exhibiting negative correlation with its sense-antisense gene BGIBMGA007380-TA in silkgland, which indicated that Bm-86,Bm-152 might be involved in the development of silkgland through regulating the expression of their host gene .In order to study the accurate location of these silkgland-rich ncRNAs, RT-PCR were taken out to anslysed the expression these six ncRNA in anterior silkgland, middle silkgland and posterior silkgland, results showed that all the six ncRNAs can be detected in different parts of silkgland. While Bm-86 and Bm-159 accumulated more in the anterior silkgland and posterior silkgland, Bm-18 and Bm-101 accumulated more in anterior silkgland. Besides Bm-101 was only detected in nucleus, the other five ncRNAs can be detected in both nucleus and cytoplasm, containing both snoRNAs and unclassified ncRNAs, which indicated that these ncRNAs might participate in regulations in both nucleus and cytoplasm.