Structure And Expression Characteristics Of The Y Chromosome Genes And The CNV Of Multi-copy Genes In Sheep

Mammalian Y chromosome genes in the male-specific region are predominantly or specifically expressed in the testis and are closely associated with testicular growth and development.Y chromosome has a complex structure and that is species specific.Although a sketch of the Y chromosome sequence of sheep has been published,the structure and expression characteristics of the contained genes and the copy number variation（CNV）of multi-copy genes are yet to be studied in depth.Using the RNA sequencing of testes from male Hu sheep at different developmental stages,including0-month-old（neonatal）,3-month-old（puberty）,6-month-old（sexual maturity）and12-month-old（body maturity）,and the Isoform-sequencing of mixed samples of testes at different months of age,the sheep Y chromosome gene structures were finely annotated and the expression characteristics were verified based on the published Y chromosome genome of Hu sheep（GCA＿011170295.1）and the genome of sheep（Oar＿rambouillet＿v1.0）.The related expression results were verified by q PCR.The CNV characteristic of two multi-copy genes,HSFY and TSPY,in different breeds and the correlation between CNV and testis size in Hu sheep were determined by q PCR,which provides a basis for the Y chromosome genes and sheep breeding.The main findings of this thesis are as follows.（1）We optimized the original gene annotation model by multi-omics data.Ten single-copy genes were annotated on the Y chromosome in sheep and the detailed gene structure of each gene was obtained.Based on the RNA-Seq data of testes at different months of age,the expression of 10 genes was evaluated in Hu sheep at various developmental stages.The expression of DDX3 Y,ZRSR2Y and OFD1 Y genes increased with age.The expression of AMELY,RBMY,ZFY,UTY,SRY,EIF2S3 Y and USP9 Y did not show a temporal manner in testicular development.（2）Four multi-copy genes were annotated in sheep,including TSPY,ZNF280 BY,HSFY and PRAMEY,of which TSPY was first reported here.RNA-Seq data showed that the expression of four multi-copy genes increased with age.The change of expression was significant between 3-month-old and 6-month-old.q PCR revealed that HSFY and TSPY were mainly expressed in testis.The expression of HSFY and TSPY was significantly higher in testis than in heart,liver,spleen,lung,kidney and muscle tissues.（3）We studied the CNV of TSPY and HSFY in 492 rams from eight breeds by q PCR.TSPY and HSFY genes were found to have CNV in all eight breeds of sheep.The results showed that the median copy number（MCN）of the TSPY gene was57（range 2-207）.Of these,South African Mutton Merino（77,range 9-152）and Dorper（77,range 3-120）had the highest median CN of TSPY,whereas Tan sheep（20,range10-92）had the lowest MCN of TSPY.The MCN of HSFY was 5（range 1-24）.The MCN of the HSFY gene was highest in South African Mutton merino（7,range3-12）and lowest in Tan sheep（1,range 1-16）.The CNV of the TSPY gene was significantly associated with partial testicular trait.