Objective To develop a simple and quick method for detection of stress-induced 5′transfer RNA( tRNA) halves.Methods Total RNA purified from stress induced cells was polyadenylated by poly( A) polymerase, and then degen-erate DNA probes were used to hybridize with 3′tRNA-halves of intact tRNAs,while RNase H specifically degraded the 3′tRNA-halves strand in tRNA-DNA probes hybrids.Using the RNase H digestion total RNA as templates, complementary DNA( cDNA) was synthesized by oligo ( dT) n-anchored primers.The primer of 5′tRNA halves and anchored-primer were used to amplify 5′tRNA halves by PCR.Results The results showed that the method of poly ( A )-tailed-RNase H digestion-RT-PCR could be successfully used to detect stress-induced 5′tRNA halves.Conclusion A simple and quick method for detection of 5′tRNA halves has been established,which is a user-friendly tool for 5′tRNA halves detection and function research.

Objective To establish RNase L gene knockout HEK 293 cell lines using CRISPR/Cas9 system.Methods Small guide RNA ( sgRNA) sequences of human RNase L were designed and sgRNAs were inserted into pCas-Guide and pCas-guide RNA(gRNA) vectors were obtained.The donor DNA sequences of the homologous arm were designed for RNase L knockout .In the presence of the right homologous arm , the resistance gene of hygromycin B and the left homologous arm as templates of homology-directed repair , the donor DNA template was amplified by overlopping PCR and cloned into the pBackZero-T expression vector and pBackZero-T-RNase LK vector was obtained .The pCas-gRNA vector and pBackZero-T-RNase LK vector were co-transfected into HEK293 cells to establish the stable expression cell line of RNase L gene knockout .Cells were cultured with hygromycin B , while Western blotting and DNA sequencing were used to analyze the gene of RNase L knockout from genome .Results and Conclusion The pCas-gRNA vector and pBackZero-T-RNase LK vector were successfully constructed.Five RNase L gene knockout HEK293 cell lines were generated,contributing to the study of the biological function and molecular mechanism of RNase L .

Objective To conduct a pilot study on genome-wide in vivo protein-RNA interactions in E.coli.Methods Bacterial lysate was treated with RNase before the RNA fragments protected by proteins were extracted from treated lysate and used to construct cDNA library that was applied to high-throughput sequencing .Finally, the transcripts bound by proteins were obtained by bioinformatics analysis .Results A total of 3193 transcripts were obtained , including 2234 mRNAs, 47 sRNAs, 39 tRNAs, 11 rRNAs, and 862 intergenic regions .Conclusion Some information of transcripts interacting with proteins in E.coli is acquired , which will facilitate further studies of protein-RNA interactions .

Objective To develop and optimize a new method to extract miRNAs from plasma.Methods miRNAs were extracted from plasma by mixing it with the extraction solution that contained surfactant and by heating .Then the ribonuclease inhibitor was added into the extraction to prevent RNAs from degradation .The expression level of each miRNA was detected by real-time quantitative PCR in oder to evaluate the feasibility of this method .Results A method which extracted miRNAs from plamsa in just one step was established .The specificity , reproducibility and stability of this method have been demonstrated by real-time quantitative PCR .Conclusion The one-step method is simple , inexpensive , and plasma-saving.It seems like a new method for clinical examination of miRNAs from plasma .

Objective To evaluate the effect of Oncomelania hupensis snail control of cutting the beach group in the south of Shaobo Lake. Methods The general situation of the project of cutting the beach was surveyed, and the snail distribution was surveyed and the results were compared before and after cutting the beach in the beach group. Results The area of cutting beach was 928.33 hm², the cubic meter of earthwork was 1 717.00 m³, the area of dumping ground was 425.76 hm², the beach surface elevation was 3.2 m after cutting the beach, and the beach surface was fallen to 1.0 m under the ordinary water level. The area with snails was 44.69 hm² before cutting the beach in 2011 but the area with snails was 1.78 hm² after cutting the beach in 2018. The area with remaining snails was declined by 96.02% in 2018 as compared with that in 2011, and surviving snails were distributed on the uncut beach face. Conclusion In Shaobo Lake, the O. hupensis snail breeding environment is eliminated by raising or lowering the beach, so it is an effective measure of snail control in lake regions.

Objective : The CRISPR / dCas9-SAM system was used to explore genes related to the proliferation of gastric cancer cells AGS，and their role in the occurrence and development of gastric cancer was analyzed． Methods : sgRNA was designed for genes with differential expression between gastric cancer and normal gastric tissue， and a lentiviral library was obtained after packaging was constructed．The AGS cells at different time points after the library was infected with AGS cells were used as the screening pressure，and the AGS cells at three time points on days 0，7 and 14 were collected．High-throughput sequencing analyzed sgRNA enrichment in AGS cells at dif- ferent time points after infection to obtain differential genes related to AGS cell proliferation. Results : Bioinformat- ics showed that compared with the 0 d group，42 and 45 negative screening differential genes and 59 and 40 posi- tive screening differential genes were obtained in the 7 d group and 14 d group，respectively．Among them，the 7 d group and the 14 d group had 11 genes in the negative screening and the positive screening． Conclusion In this study，11 genes inhibiting the proliferation of AGS cells were screened，of which 5 were protein-coding genes and 6 were long non-coding RNA ( lncRNA ) genes． 11 candidate genes that promoted AGS cell proliferation were screened，of which 3 were protein-coding genes and 8 were lncRNA genes．It laid a foundation for further function- al verification and comprehensive analysis of the occurrence and development process of gastric cancer.