| A few years ago, PIWI-interacting RNAs(piRNA) have been discovered. Now, piRNAs are attracting many scientists, for their variety, their distribution, and their loci only in animal germline cell. Some research results of piRNAs’ function have been published in Cell, Science, Nature and other academic journals. The scientists’ enthusiasm in studying piRNAs’ function has been inspired. In Caenorhabditis elegans, prg-1 plays the key role in piRNAs biogenesis, but some important questions are unkown, such as, how the piRNA are transcripted and what the details of piRNAs function is. All of these are all charming the scientists. A few exciting results show that the scientists have a breakthrough in C.elegans piRNA’s function research. They have found that piRNA could match its targets sequence with less than 3bp mismatch, and could active the RDRP to transcript some small RNAs around the piRNAs targets sites, and then these small RNAs could take part in silencing the piRNAs’ targets, but the piRNAs could not play special roles in slicing or suppressing(silencing) the piRNAs’ targets directly. One of the challenges is that the details of piRNAs function are not clear. In addition to silencing the targets, PRG-1 protein also regulate the reproductive development of nematodes, and the inhibition of transposons’ translocation. As a result, prg-1 gene has the various roles in mRNA expression, transposon silencing, mRNA slicing and small RNAs biogenesis.C.elegans are bred in this research and the worm are collected at L4 period. Use Trizol to extract the RNA, sequence the RNA by the next generation sequencing technology, and use the bioinformatics to analyse the RNA sequence data to find the expression change of small RNA, mRNA and mRNA slicing. All of the results include four parts.1. 967 new piRNA are identified. These new piRNAs have the characteristics of nematodes known-piRNA, with 21 nt length, U as the first base, to form compounds with PRG-1, and to disappear followed the prg-1 mutation.2. Explain the biogenesis of some small RNAs. piRNA-like and miRNA-like are unknown small RNAs, but have the same gene loci and same expression mode with piRNA and miRNA, respectively. All of these show that piRNA and piRNA-like or mi RNA and miRNA-like are sliced from the same piRNA precursor or miRNA precursor. These results suggest that precursors have difference processed modes.3. Find 1031 differentially expressed genes. 509 genes’ expression levels are up, and 522 genes’ expression levels are down. The GO analysis results show that these genes have the enrichment sites in the oxidation-reduction enzyme and in the extracellular components, and would take part in the worm growth. The KEGG analysis results show that the differentially genes are enriched in the fatty acid metabolism, the exogenous substance metabolism mediated by P450, and the retinol metabolism. The GO and KEGG results can help other researchers to find the interesting genes to explore genes’ unkown function.4. Some mRNAs can be sliced by some unkown small RNAs. Some small RNAs can be enriched at the downstream of mRNA sliced site, and the enriched sites can been changed from 10 nt to 20 nt at the downstream of mRNA sliced site followed prg-1 mutation. But the expression levels of the small RNAs’ targets do not change. The phenomenon suggest that some small RNAs may play special roles to their targets. All of these suggest that PRG-1 can regulate the some small RNA transcription site to change these small RNAs’ slicing site, but cannot change these small RNAs’ targets expression level.As a result, four main phenomenon are showed in this paper. The found of new piRNAs tell us that the piRNA loci are diversity. The genesis of piRNA-like and miRNA-like suggest that a precursor piRNA or mi RNA transcript can have difference slicing mode. PRG-1 can change same genes expression level, but the expression of the targets of pi RNA or miRNA are not impact, but some small RNAs may take part in some mRNAs’ slicing. |
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