Optional Endoreplication and Selective Elimination of Parental Genomes during Oogenesis in Diploid and Triploid Hybrid European Water Frogs.

Dmitry Dedukh,Alsu Saifitdinova,Glib Mazepa,Alla Krasikova,Juriy Rosanov,Spartak Litvinchuk,Dmitry Shabanov,Pawel Michalak

doi:10.1371/journal.pone.0123304

Dmitry Dedukh, Alsu Saifitdinova + Show 6 more

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https://doi.org/10.1371/journal.pone.0123304

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Abstract

Incompatibilities between parental genomes decrease viability of interspecific hybrids; however, deviations from canonical gametogenesis such as genome endoreplication and elimination can rescue hybrid organisms. To evaluate frequency and regularity of genome elimination and endoreplication during gametogenesis in hybrid animals with different ploidy, we examined genome composition in oocytes of di- and triploid hybrid frogs of the Pelophylax esculentus complex. Obtained results allowed us to suggest that during oogenesis the endoreplication involves all genomes occurring before the selective genome elimination. We accepted the hypothesis that only elimination of one copied genome occurs premeiotically in most of triploid hybrid females. At the same time, we rejected the hypothesis stating that the genome of parental species hybrid frogs co-exist with is always eliminated during oogenesis in diploid hybrids. Diploid hybrid frogs demonstrate an enlarged frequency of deviations in oogenesis comparatively to triploid hybrids. Typical for hybrid frogs deviations in gametogenesis increase variability of produced gametes and provide a mechanism for appearance of different forms of hybrids.

Highlights

Interspecific hybridization usually leads to death or sterility of hybrid animals [1], [2]
To test our hypotheses we examined lampbrush chromosome sets in oocytes from diploid and triploid hybrid P. esculentus frogs taken from the population systems of R-E type located in the East of the Ukraine
The individuals with a range of C-values between 16.00±35 were designated as P. ridibundus, individuals with a range of C-values between 14.00±35 were designated as P. lessonae, while individuals with a range of C-values between 14.90±35 were designated as P. esculentus and triploid hybrid frogs with LLR and RRL genotypes have range of C-values between 21.80±35 and 22.9±35 correspondingly [21]

Summary

Introduction

Interspecific hybridization usually leads to death or sterility of hybrid animals [1], [2]. In vertebrate hybrids, deviations from canonical gametogenesis and meiosis give rise to a variety of successful reproduction modes, such as parthenogenesis, gynogenesis, kleptogenesis and hybridogenesis [3,4,5,6,7]. Such deviations in gametogenesis include chromosomal endoreplication and elimination [8,9]. Chromatin elimination occurring in germ cells leads to selective (in case of hybridogenesis and pre-equalizing hybrid meiosis) or nonselective

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