Genetic Research On Genes Related To Prolificacy Of Little-tailed Han Sheep And Bioinformatics Analysis

The Little-tailed Han Sheep is a kind of famous sheep line with multiplets and non-season oestrum in the world . Uncovering the regulatory mechanism of multiplets on the level of molecular biology is the base to find the molecular mechanism of high fertility , which can be used in the breeding, and select the precise location on marker assistant selection (MAS).The cDNA library of ovary from Little-tailed Han sheep in the estrus was firstly constructed by SMART (switching mechanism at 5' end of RNA transcript) in the world . The plaque titer of this library was 1×10~9pfu/ml, the recombinant percentage was 96%, and the average fragment length of inserted cDNA was 1.5kb.On the base of the construction of ovary cDNA library on Little-tailed Han sheep and the latest bioinformation , we got the special expression genes EST by screening and hybridizing the ovary cDNA library with the probes labeled by gene fragments on other species associated genes . The results showed that the homologous genes of Prostate gland, Inhibin, FSHR, ESR, TGFβ and EGF genes related to ovulation rate could be screened and cloned from the cDNA library. This efficient and quick method is a foundation to fish out the major gene of ovulation.Using the EditSeqwe program of DNAstar software and the ORF Finder program of NCBI , we analysed the open reading frame(ORF) of the nucleic acid sequences which we had acquired . When we analyse the inserted sequence of cloning , we can find the full sequence of ORF and the fragments of 5' and 3' non-coding sequence , so we can ascertain that they are the full cDNA . But this is the analysis result of the computer , whether they are the full fragments of cDNA which have a biological characteristic we must validate them by more experiments .A lot of data indicated the nucleic acid segments of 150bp~400bp contains enough information about sequence appraisal and the orientation of chromosomes (Durkin et al,1994;Touchman et al,1997)0 So,it can be sure that they truly reflect the expression of genes in some specific cells or tissues under the specific circumstances , despite the sequences we had acquired do not always contain the full length of ORF . By it, we not only acquire a set of integrated sequences, but also know its expressing model .Some specific ESTs of Little-tailed Han sheep were screened, and they had been submitted to GenBank(GenBank accession numbers are DR033901, DR033902 > DR033903 ^ DR033904, DR033905 and DR033906), which will enrich the ESTs database of sheep.