Improved induction of meiotic gynogenesis in Coruh trout, Salmo coruhensis

Abstract

In this study, water and spermatozoa parameters were evaluated during the reproduction season, as well as the optimal conditions for the retention of the second polar body in Salmo coruhensis eggs obtained with heat-shock timing, intensity, duration and UV irradiation for gynogenetic production. Sperm was diluted 1:20 with lightly modified Hank's Balanced Salt Solution, and sperm manifesting 60% motility was obtained with a UV dose of 3600 kJ/cm2. The highest ratios of eyed-stage, hatching and larval survival were 89.59 ± 2.18%, 82.86 ± 3.11% and 79.61 ± 1.25% in the experimental group exposed to 28.5 °C heat-shock respectively. As the shocking temperature increased, the rates of eyed-stage, hatching and larval survival decreased (p < 0.05). After 3–7 days of fertilization, all haploid individuals died in all experimental groups. As a result of the morphological examination, no difference was found between the gynogen and control groups at larval and juvenile stages. In karyotype analysis, chromosome numbers of control (C), diploid gynogen (G) and triploid (T) group were 2n = 80 and 3n ≈ 120 respectively. Triploid groups showed 1.5 times higher mean erythrocyte diameter and relative DNA content than G and C groups. Moreover, it was determined that sdY, the salmonid male sex-determining gene, was not found in all groups that were assumed to be gynogens, and all of them were female (100%). These results indicated that all individuals in the gynogen groups were gynogenetic. The protocol developed in this study can contribute to the production of gynogenetic Coruh trout, the production of mono-sex species, as well as the genetic performance enhancement studies.