Induced meiotic gynogenesis in shovelnose sturgeon

Abstract

Gynogenesis was induced in three shovelnose sturgeon (Scaphirhynchus pIatorynchus) by heat shock after egg activation with UV-treated paddlefish (Polyodon spathula) milt. Ultraviolet dosage (J m−2) for the pooled milt samples was calculated using the following linear regression equation: Dosage = 2405.27 − 352.80X 19.78X2 (X = percent transmittance of milt). Activated eggs were incubated at 18 °C until shocking at 35 °C. Shock duration was applied at 0.05τ0 intervals from 0.15 to 0.40 τ0 (8.25 to 22.00 min post-fertilization; τ0 at 18 °C = 55 min). The highest yield of gynogenotes (16%) was observed at 0.25 τ0 for female 3, 10 % at 0.30 τ0 for female 2 and 12% at 0.35 τ0 for female 1. The percentage of viable gynogenotes responded quadratically to the tau index (τs/τ0) when shock treatments were applied. The higher yields of viable diploid sturgeon gynogenotes were achieved when eggs were heat shocked at embryological ages ranging from 0.25 to 0.35 τ0 (approximately 14 to 19 min post-activation at 18 °C). No viable hybrids were produced in the control fertilization of sturgeon eggs with intact paddlefish sperm which verified the gynogenetic origin of the offspring produced. © Rapid Science Ltd. 1998