Effects of Hydrostatic Pressure Treatment of Newly Fertilized Eggs on the Ploidy Level and Karyotype of Pikeperch Sander lucioperca (Linnaeus, 1758).

Jenő Káldy,Zsuzsanna J Sándor,Katalin Goda,Bence Lázár,Katalin Bogár,Ákos Horváth,Gyula Kovács,Zoltán Nagy,Eszter Patakiné Várkonyi,Georgina Lea Fazekas,Péter Nánási,Uroš Ljubobratović,Zsuzsanna Gyöngy,Zsuzsanna Ritter,Mariann Molnár

doi:10.3390/life11121296

Abstract

We studied the effect of different magnitudes (7000 PSI (48.26 MPa), 8000 PSI (55.16 MPa), and 9000 PSI (62.05 MPa)) of hydrostatic pressure on the ploidy of pikeperch larvae. Pressure shock was applied 5 min after the fertilization of eggs at a water temperature of 14.8 ± 1 °C. A 7000 PSI pressure shock was applied for 10 or 20 min, while 8000 and 9000 PSI treatments lasted for 10 min. Each treatment with its respective control was completed in triplicate, where different females’ eggs served as a replicate. In the treatment groups exposed to 7000 PSI for 10 min, only diploid and triploid larvae were identified, while 2n/3n mosaic individuals were found after a 20-min exposure to a 7000 PSI pressure shock. The application of 8000 or 9000 PSI pressure shocks resulted in only triploid and mosaic individuals. Among larvae from eggs treated with 8000 PSI, three mosaic individuals with 2n/3n karyotype were identified (4.0 ± 6.9%), while a single (2.0 ± 3.5%) 1n/3n mosaic individual was found in the 9000 PSI-treated group. To our knowledge, this is the first report that demonstrates the induction of a haplo-triploid karyotype by hydrostatic pressure shock in teleost fish. The dominance of triploid individuals with a reasonable survival rate (36.8 ± 26.1%) after 8000 PSI shock supports the suitability of the hydrostatic pressure treatment of freshly fertilized eggs for triploid induction in pikeperch.

Highlights

The phenomenon of polyploidization means that an organism possesses three or more chromosome sets
Our experiments demonstrated that 7000 pound per square inch (PSI) pressure shocks resulted in an approximately 90% triploid ratio in pikeperch
Our experiments demonstrated that a hydrostatic pressure shock applied 5 min after fertilization effectively induces triploidy in pikeperch

Summary

Introduction

The phenomenon of polyploidization means that an organism possesses three or more chromosome sets It occurs naturally in many taxa of teleost fishes (e.g., Cypriniformes, Salmoniformes, Perciformes, and Siluriformes), as a result of chromosome multiplication during evolution [1,2]. When fertilized eggs were treated with pressure, cold, or heat shock shortly after fertilization, triploid progenies were obtained, because the treatment inhibits the expulsion of the second polar body from the egg during the second meiotic division [6,7,8] In this case, the triploid offspring inherits two maternal and one paternal chromosome sets [9]. Glover et al (2020) [10]

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Conclusion