Induction of meiotic and mitotic gynogenesis in silver barb (Barbonymus gonionotus) through cold shock treatment

This study was dealt with induction of diploid meiotic and mitotic gynogenesis in Barbonymus gonionotus through cold shock treatment for production of monosex all-female population. For inhibition of paternal inheritance, sperm DNA was denatured by exposing cell suspension containing 8x10(8) ml(-1) to UV at 196 mu Wcm(-2) for 1.5 min. After fertilization of eggs using uv-treated sperm, meiotic diploidization was done by cold shock treatment at 2 degrees C for 1 min applied 1.5 min of post-fertilization that produced 44.23 +/- 0.62% meiotic gynogens. Mitotic diploidization was done by the same cold shock treatment applied after 27.5 min of fertilization that produced 36.70 +/- 0.63% mitotic gynogens. Ploidy status of all the progenies was evaluated by karyotyping. The karyotype analysis revealed 23 (N) chromosomes in haploids, and 46 (2N) chromosomes in meiotic and mitotic gynogens and controls. Sexing of fish showed nearly all-female, ranging from 98.28 to 100% and 96.43 to 100% female in the meiotic and mitotic gynogens respectively. The sex ratio in the control group was nearly 1:1. DNA microsatellite analysis revealed that the meiotic gynogenetic offspring possessed two alleles the same as their mother and the mitotic gynogenetic offspring possessed any of the two alleles of their mother and became homozygous. No meiotic and mitotic gynogens have inheritance of paternal alleles. The control offspring shared alleles from both male and female parents. Thus, the study confirmed the production of meiotic and mitotic gynogens of silver barb through cold shock treatment and they could be converted into sex-reversed males (XX) by masculinizing hormone treatment for production of monosex all-female population.

Automated summary

This study induced diploid meiotic and mitotic gynogenesis in Barbonymus gonionotus through cold shock treatment for production of monosex all-female population. Karyotype analysis showed the ploidy status of the offspring, and DNA microsatellite analysis revealed that the gynogenetic offspring possessed maternal alleles only, with paternal inheritance inhibited. The gynogens could be converted into sex-reversed males (XX) through masculinizing hormone treatment.