Genetic Inactivation of Stinging Catfish (Heteropneustes fossilis) Sperm with UV Irradiation

Abstract

To improve the efficiency of gynogenetic induction, the effect of UV light on sperm of Heteropneustes fossilis was optimized. The sperm suspension was diluted to 1 × 10⁷ sperm/ml⁻¹ in Hank's Balanced Salt Solution. Sperm suspension was irradiated under UV light for different exposure times ranging from 15 to 360 seconds (7500 ergs/mm⁻² for 60 seconds). Sperm motility and egg activation efficiency were assessed for the different exposure durations. Complete inactivation of sperm genetic material was recorded from 120 seconds onwards, and a good motility score was recorded until 240 seconds. A typical “Hertwig effect” in the yield of hatched larvae was observed with doses of UV exposure greater than 75 seconds. Larvae resulting from sperm UV irradiated above 120 seconds were 100% haploid. The genetic inactivation of paternal chromosomes was confirmed by chromosome counting (n = 29) from the resulting embryo, which also had a characteristic haploid syndrome. The resulting embryo (with 29 chromosomes) exhibited haploid syndrome and died after yolk sac absorption.

KEYWORDS:

• Heteropneustes fossilis
• gynogenetic haploid
• haploid syndrome
• Hertwig effect
• UV irradiation

Acknowledgments

The work was funded by the Indian Council of Agricultural Research, Government of India. The first author would like to express his special gratitude to Ms. Rosalie Shaffer, Information Specialist, NMFS Library, USA, for providing necessary reference materials.