Preliminary Research On Genetic Characteristic Of The Multiple Pengze Crucian Carp

Known as gynogenetic crucian carp in China, Pengze crucian carp {Carassius auratus of Pengze), just like Silver crucian carp, is an endemic bisexual population with natural gynogenetic reproduction mode. The multiple pengze crucian carp is the minority of the offspring of Pengze crucian carp activated by heterogenous sperm, and possesses some obvious patrilineal characteristics, for example the length of rostrum, the apophysis of the back and the color of the lateral scales and so on.In the thesis, embryonic and larval development and four isozymes(ME, MDH, EST and SOD) were analyzed respectively in two offspring of the multiple pengze crucian carp, activated by homologous and heterogenous sperm. The DNA content of the multiple pengze crucian carp and its parents were mensurated and analyzed. The development mode, genetic background and possible mechanism of creation of the multiple pengze crucian carp were discussed.The results showed that: (1) On the procedure of embryonic and larval development and the brief characteristics of each stage, there were no obvious differences between two offspring of the multiple pengze crucian carp, activated by maternal (Carassius auratus of Pengze ) and paternal (sea carp) sperm respectively. And they were obviously different from Carassius auratus of pengze ( ) xsea carp( ). (2) Except the discrimination on the dyeing intensity of EST and SOD between two offspring, there were no difference on the removing rate and number of isozyme bands. (3) The value of DNA content of Carassius auratus of Pengze is 1.57 times as many as that of Cyprinus acutidorsalis Wang, and this results accords with the fact that Carassius auratus of Pengze is triploid. The DNA content of the multiple pengze crucian carp is much more than that of Carassius auratus of Pengze, the value of majority is close to or more than that of tetraploidy, the rest is less than tetraploidy.The above results suggested that: (1) The multiple pengze crucian carp inherited the characteristic of gynogenesis from its female parent- Carassius auratus of Pengze.(2) Different sperms had no influence on the embryonic development of the multiple pengze crucian carp basically, the difference of expression intensity of two isozymes (SOD and EST) was not considered to be as assured evidence. (3) According to the results of DNA contents of the multiple pengze crucian carp, few eggs of Carassius auratus of Pengze were supposed to possesses two reproduction modes-gynogenesis and zoogamy, i.e., those eggs can fuse with some or all chromosomes of paternal parent. (4) Based on the difference degree of the DNA content between the multiple pengze crucian carp and tetraploidy and the fact that the DNA content of Cyprinidae fishes ranged over biggish extension, some individuals were presumed to be the multiple tetraploid allogynogenetic pengze crucian carp whose DNA content was close to or more than that of tetraploidy, and other individuals were presumed the multiple aneuploid pengze crucian carp whose DNA content was less than tetraploidy. (5) The difference of the DNA content between the multiple pengze crucian carp implied that the potential of fusing with chromosomes of paternal parent was probably different between few eggs of Carassius auratus of Pengze, but underlying reason was still far from clear.The multiple pengze crucian carp possesses special significance to the research of the monosexual, especially bisexual fish. It is not only one favorable material to research the mechanism of gynogenesis, but also have tremendous potential on breeding.