Studies On The Characteristics Of Ovarian Development Of The Hybrid F₁ Of Ctenopharyngodon Idellus?×Squaliobarbus Curriculus?

Grass carp?Ctenopharyngodon idellus?is part of leuciscinae,the annual production occupies a important position in freshwater fish industries of China.However,grass carp hemorrhage virus?GCHV?which is considered to be the most pathogenic aquareovirus seriously threats the grass carp aquaculture industry.Squaliobarbus curriculus,which is belong to the same subfamily,has a strong ability of resistance.To enhance the disease resistance of grass carp,our team had spread the hybridization experiment in C.idellus and S.curriculus.In the study,organization structure,chromosome karyotype,DNA content in nucleus of erythrocyte,sexual steroid hormone and expression of some genes were studied to explore the characteristics of gonad development,ploidy and fertility in the ovaries in hybrid F₁ of Ctenopharyngodon idellus?×Squaliobarbus curriculus?.The main results are as follows:1.The morphological character and structure of gonadal microscopic examination in hybrid F₁.The results of anatomical observation and histological section showed that there were two types of ovary.One type was normally developed,different developmental stages of oocytes were observed and they could be used to produce next generation;the other type could develop to phase IV and gradually became abnormal in phase?,which with the yolk granules degraded or without egg yolk.The testis-type of gonad mainly included primary spermatocytes,secondary spermatocytes and spermatozoons,without mature sperm;partial lobules were full of connective tissue or adipocyte and few androcytes.Until now,semen had not been found in the production practice.2.The chromosome karyotype and DNA content in nucleus of erythrocyte in hybrid F₁.The number of chromosome was 2n=48,the karyotype formula was2n=26m+20sm+2st,NF=94,and the terminal chromosome,satellite and secondary constriction were not observed.The DNA content of erythrocyte in hybrid F₁ was?3.21±0.61?pg·N^-1,and it was 1.29 times as content as chicken.The above result had proved the hybrid F₁ was diploid.3.The content of sexual steroid hormone of blood serum in hybrid F₁.The maturity of ovary had no connection with weight and age.No matter what sample had collected,the content of luteinzing hormone,follicle-stimulating hormone and progesterone was highest in four years old,the content of estradiol was lowest in thress years old.4.The analysis of expression of some genes which is related to ovary in hybrid F₁.The result of real-time quantitative PCR of wnt4?foxl2?cyp19a?dax1 and esr2a,which was overexpression in thress years old,and the expression of sf1 has a great change at all ages.In conclusion,the consequences of four experiment had comfirmed hybrid F₁was diploid,and partial female is fertility and the male may be abortive.