Artificial Induction of Meiotic Gynogenesis in <i>Koi</i> Carp Using Blunt Snout Bream Sperm and Identification of Gynogenetic Offspring
2025
Xiaoyu Chen | Xiulan Shi | Jun Guo | Kai Lin | Mingkun Luo | Zaijie Dong
Artificial gynogenesis is an effective means of producing pure lines and is widely used for genetic analysis of fish and for sex control. In this study, inactivated sperm from heterogenous blunt snout bream (<i>Megalobrama amblycephala</i>, MA) were used to activate <i>Kohaku koi</i> (<i>Cyprinus carpio</i> var. <i>koi</i>, CK) and produce high-quality female offspring. To determine whether the offspring were gynogenetic fish, the karyotype and DNA content of the CK, MA and the induced offspring (IO) were first compared and it was found that the IO were diploid with 100 chromosomes and their karyotype was 22m + 34sm + 22st + 22t. The DNA content of the IO was not significantly different from that of the CK. Subsequently, the amplified band profiles of CK, MA and IO were analyzed with species-specific microsatellite markers. The results showed that there were no amplified MA microsatellite bands in IO. The size of the amplified bands and the sequence of the 5S rDNA in CK, MA and IO were also analyzed. It was found that the amplified 5S rDNA gene fragments in IO contained two fragments that were both the same size as those of CK and matched more than 90% with those of CK. Finally, the sex of IO was verified using gonadal tissue sections. The result showed that IO was not an all-female population; males were also present (36.7%). In summary, a series of validation methods confirmed that the induced offspring were gynogenetic fish, which is the basis for the subsequent genetic improvement of pure lines of high-quality <i>koi</i>.
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