Study On The Relationship Between The Infertility Of Cattle-Yak And Gene Correlated With Synaptonemal Complex

The F₁ cattle-yak is infertile, so many valuable genes can not be fixed, and that is the main obstacle of crossbreed of yak. There are a few spermatocytes observed in testis of cattle-yak. The testis observed by histology, and there is no spermatids and sperm. Only few autosomes of spermatocytes can form SC in meiosis I. The abnormality of forming SC is probably the main reason that leads to the infertility of F₁ offspring cattle-yak. SYCP1, SYCP2, SYCP3, FKBP6, the main part of SC, has a close relationship with meiosis of spermatogenesis and the lack or low expression probably lead to the abnormality of forming SC and failuar of spermatogenesis.Our study mainly show the expression of SYCP1, SYCP2, SYCP3, FKBP6 and analysis their expression levels between yak and cattle-yak testis. The results are as follow:1. The seminiferous tubule of cattle-yak is much smaller than that of cattle, the space between tubules is big, the size and shape of lumen is different, the tube wall is wizened, and there is no or only a thin flat of spermatogonia in epithelium of seminiferous tubule. Little primary spermatocyte can be seen, and no secondary spermatocyte, no sperm in epididymis; however, the seminiferous tubule tissue of yak testis develop normally, and there are all levels of spermatogenic. The sperm, which can be observed in epididymis, develop well. The failure of spermatogenesis leads to cattle-yak infertility directly.2. SYCP1, SYCP2, SYCP3, FKBP6, which corrleted with SC, express specifically in yak testis, may play an inportant role in meiosis and they are the important candidate genes of spermatogenesis.3. SYCP1 expresses in yak and cattle-yak testis, and the expression level is no significant difference between yak and cattle-yak (P>0. 05 ) , which proves that SYCP1 probably has no relationship with cattle-yak infertility.4. SYCP2 expresses in high level both in yak and cattle-yak, however there is difference between them (P<0.05), consistent with the result of spermatogenic failure in cattle-yak, which proved that SYCP2 probably has a relationship with cattle-yak infertility.5. SYCP3 expresses in yak and cattle-yak testis, however there is significant difference between them (P<0.01), the same characterization as SYCP3 low expression in azoospermia men, which proved that SYCP3 probably has a relationship with cattle-yak infertility.6. FKBP6 express in yak and cattle-yak, but there is significant difference between them (P<0.01), it shows that FKBP6 probably has a relationship with cattle-yak infertility.Some genes which associated with SC of lower express in the testis probably have a relationship with cattle-yak infertility.