Production and progeny testing of androgenetic rosy barb Puntius conchonius

Abstract

Protocol for androgenetic cloning of the rosy barb, Puntius conchonius, with contrasting gray and golden strains is described. At the intensity of 4.2 W/m², UV irradiation for 3.0 min inactivates the maternal genome in eggs of the gray barb. Following activation by the golden barb sperm, 24-min old eggs are shocked at 41°C for 2 min to restore diploidy. Maternal genomic inactivation is confirmed by the (i) golden body color, (ii) karyotyping, and (iii) progeny testing of F₁-F₃ progenies. Estimates of stage-specific mortality of haploid and diploid androgenotes indicate no change in the time scale or developmental sequence, when sperm of related strain is used for activation, and when haploid genome regulates the development. Survival of androgenetic clones remains constant for the F₁, F₂, and F₃ progenies and is about 15% and 7% at hatching and sexual maturity, respectively. Homozygosity of the androgenotes is shown to inflict greater mortality. Between F₁ and F₃ generations, the heterozygosity of the androgenetic clone is decreased, as evidenced by reduction in size hierarchy. Though the reproductive performance of the F₁, F₂, and F₃ supermales is superior to the normal ones, the realized fecundity remains equal around 80 progenies per brood. The 92 crosses involving 16 supermales and 10 normal dams yield 75-100% male progenies, confirming the possible operation of XX♀:XY♂ sex determination system. The frequency of unexpected occurrence of female progenies is about 8%, the causes for which are discussed.