Screening，Identification And Sequence Analysis Of Cashmere Goat Y Chromosome BAC

After several centuries of natural selection and artificial selection, Cashmere goatis differentiated gradually from a goat variety and lives in a specific ecologicalenvironment. It has kinds of uses and high economic value, and has become animportant livestock resource, which it can produce rare and valuable cashmere. Atpresent, because of the gradual deterioration of the survival environment, the growthand development of cashmere goat are restricted by the ecological conditions.Thisleads to the lower degree of improved varieties, lack of high-quality stud and declinedcashmere quality. Therefore, the urgent task is to strengthen the good gene protectionof the cashmere goat, improve breeding force, increase cashmere production andimprove cashmere quality.Male cashmere goat plays an important role in the process of breeding.Not onlyit has the ability to reproduce, but also has higher cashmere yield. So, cultivating goodrams vigorously is necessary.However, ram breeding capacity mainly depends on themechanism of the genes related to reproductive traits on the Y chromosome. Becausegoat Y chromosome sequencing work has not completed, the mechanism of the genesrelated to reproduction can not be clearly understood.We screened Y chromosome sequences in cashmere goat genomic BAC libraryby PCR, identified Y chromosome sequences by FISH tecnology, assembled andanalysized sequences in this study, the main results are as follows:1.10BACs are screened out from cashmere goat genomic BAC library by PCRand identified, cloned and sequenced. At last,they are initially identified as cashmeregoat Y chromosome BAC in this study.2.614B22,516O16,405D22and570A19BAC are further mapped to cashmeregoat Y chromosome by FISH.3. After four BACs original sequencing data was first assebled by software,weobtained335contigs.103contigs of them are from614B22,135contigs are from516O16,67contigs contigs are from405D22and30contigs are from570A19. Andwe obtained314scaffolds too,98scaffolds of them are from614B22,126scaffoldsare from516O16,62scaffolds are from405D22and28scaffolds are from570A19.The sequence length of516O16BAC is the longest,while405D22BAC isthe shortest.4. Predicting the start site and the binding sites of the transcription factor ofpartial sequences of570A19BAC and516O16BAC,we obtained four start sites anda start site and many binding sites and transcription binding factors respectively.5. Both570A19BAC and516O16BAC have multiple ORFs predicted.By theprotein-coding sequences alignment, we determined they are TSPY and USP9Yprotein coding frame respectively.6. The protein structure domains are searched in all coding frames and a conserved transmembrane helix region in570A19is only predicted and a conservedtransmembrane helix region and a highly conserved domain-UCH are in516O16. Itshowed TSPY and USP9Y are less conserved among the species.7. TSPY and USP9Y protein tertiary structure prediction showed that both ofthem are composed of multiple α-helix and β-fold.8. NJ phylogenetic tree based on USP9Y genes showed that the kinships of goat,cattle, homo sapiens,macaca mulutta,eulemur fulus and other species are consistentwith the positions in the taxonomy，and cashmere goat and cattle are the closestgenetic relation and belong to a class.This research provided a theoretical basis for follow-up in-depth study oncashmere goat Y chromosome gene function, regulation of time and space, therelationships of genes and further promoting cashmere goat genetic resourceprotection and utilization,implementing sex control,shortening the ram breeding timeand improving its production efficiency.