Ploidy Variation and Viability of Aneuploid Ornamental Koi Carp Obtained by Crossing Triploid Females with Diploid Males

Abstract

Results of crossing triploid females of ornamental koi, a variant of Common Carp Cyprinus carpio, with diploid koi males in two consecutive spawning seasons (2014 and 2015) are presented. A total of seven progenies from six triploid females (one female was spawned twice) were produced and analyzed. The same as normal diploid females, triploid females were highly fertile and produced hundreds of thousands of eggs (up to 400,000 per female). Processes of embryo incubation and hatching of larvae in progenies obtained from triploid females proceeded normally; however, mass mortality of hatched larvae occurred at the swim‐up stage. Nevertheless about 200,000 swim‐up larvae were obtained and stocked for further rearing. A total of about 1,000 juveniles (or 0.5% of the number of stocked larvae) was collected from outdoor tanks. As expected, all analyzed larvae and juveniles in control progenies obtained by crosses of diploid females with diploid males were diploid. About 95% of analyzed fish (larvae and juveniles) obtained by crossing triploid females with diploid males were aneuploids with ploidy ranging from 2.14n to 3.0n; mean values of fish ploidy in progenies obtained from different triploid females varied from 2.47n to 2.63n. Since aneuploid fish have in their genomes one haploid set from parental males, the data obtained indicate that triploid koi females produced aneuploid eggs with ploidy range from haploid to diploid level and a modal ploidy level around 1.5n, similar to the production of aneuploid spermatozoa observed earlier for triploid males in fish. About 5% of juveniles obtained from triploid females had ploidy range from 3.21n to 4.0n. Apparently these fish resulted from spontaneous suppression of the second meiotic division in aneuploid eggs.

Why are triploid zebrafish all male?

“…Triploid males frequently produce aneuploid spermatozoa, whereas triploid females in most species are sterile (Benfey, ). However, triploid common carp Cyprinus carpio females have been found to produce aneuploid oocytes (Gomelsky, Delomas, & Warner, ; Gomelsky, Schneider, Anil, & Delomas, ). Triploidy is induced by applying a physical shock (temperature or pressure) to fertilized oocytes, which causes retention of the second polar body.…”

Aneuploid progenies of triploid hybrids between diploid and tetraploid loach Misgurnus anguillicaudatus in China

“…Oshima et al (2005) reported the spawning of a few diploid eggs in natural triploid loaches. A similar shift of the modal ploidy level toward 2.6n-2.7n was recently reported in the progenies of fertile induced triploid ornamental carp (Gomelsky et al 2015). This is presumably explained by selective mortality against eggs during oogenesis and the resultant zygotes (embryos) \2.5n.…”

“…In several auto-and allotriploid fishes, which were artificially induced by inhibiting the second polar body release just after fertilization, gametes with a ploidy level of approximately 1.5n have been reported (Allen et al 1986;Benfey et al 1986;Ueda et al 1987Ueda et al , 1991Van Eenennaam et al 1990;Zhang and Arai 1999;Gomelsky et al 2015). Among them, however, meiotic configurations have not been well investigated except for induced triploid Electronic supplementary material The online version of this article (doi:10.1007/s10709-016-9928-8) contains supplementary material, which is available to authorized users.…”

Meiotic chromosome configurations in triploid progeny from reciprocal crosses between wild-type diploid and natural tetraploid loach Misgurnus anguillicaudatus in China

“…25I, but induced triploid females could not form fertile eggs (Zhang and Arai 1999). However, it was reported that induced triploid koi (ornamental carp) females spawned fertile eggs and then produced viable aneuploid (mean value 2.6n, range 2.3n to 2.9n) progeny after crossing with diploid males (Gomelsky et al 2015). Unexpected well-developed ovaries were also reported in common carp (Wu 1990;Cherfas et al 1994).…”