small non-coding RNA expression profile in F1 progeny from irradiated adults zebrafish
In order to investigate transcriptomic mechanisms underlying radiation exposure, we exposed zebrafish (~6 month old) to 8.7 mGy/h of g-radiation (5.2 Gy total dose) during gametogenesis for 27 days. F1 offspring from exposed parents were sampled at 5.5 hpf (late blastula/early gastrula) one year after parental exposure, for small RNA sequence analysis to determine changes in the sncRNA expression profile. Pairwise comparison between F1 generation from exposed (F1-?), and control (F1-C) parents, revealed several classes of sncRNAs and one class of lncRNA differentially expressed. Overall, 22 miRNAs, 11 piRNA clusters, 19 snRNAs, and 21 lincRNA were found differentially expressed. When linking the DEmiRs to our previously published mRNA data, a total of 672 differentially expressed mRNAs could be linked to the DEmiRs, of which 380 followed the canonical inverse relation in miRNA-mRNA interaction. Pathway analysis revealed these 380 mRNAs involved in insulin receptor, NFkB and PTEN signaling, linking to apoptosis and cancers. The 84.2% of differentially expressed snRNAs were down-regulated in the F1-? group, 68.8% of which were U1 and U2 snRNAs. In addition, 45% of differentially expressed DEpiRNA clusters were found associated to 9 TEs (LTR, LINE, and TIR) (p=0.0024). DEpiRNA clusters were expressed from the opposite strand of the associated TEs, indicating expression of DEpiRNAs in response to activation of TEs. Finally, 66.7% and 33.3% of lincRNAs in F1-? were down- and up-regulated respectively. The cancer and development related lincRNAs malat-1 was found among the most down-regulated genes, denoting a link between lincRNAs expression and altered phenotypes reported previously in our parallel studies. Overall design: One year after parental exposure during gametogenesis to 60Co source at 8.7 mGy/h (5.2 Gy total dose), three biological replicates of F1 embryos were collected in pools of 100 individuals from both exposed and control groups. Total RNA corresponding to sampled embryos in each experimental group was extracted and sent for small RNA sequencing under platform Illumina 4000. The 6 small RNA libraries obtained from 3 biological replicates in each experimental group were analyzed for small non-coding RNA profiling and differential expression.