Chromosome doubling in early spermatogonia produces diploid spermatozoa in a natural clonal fish

Biology of Reproduction
Hiroyuki YoshikawaKatsutoshi Arai

Abstract

The natural clonal loach Misgurnus anguillicaudatus (Teleostei: Cobitidae) is diploid (2n = 50) and produces genetically identical unreduced eggs, which develop into diploid individuals without any genetic contribution from sperm. Artificially sex-reversed clones created by the administration of 17alpha-methyltestosterone produce clonal diploid sperm. In metaphase spreads from testicular cells of the sex-reversed clones, spermatocytes had twice the normal number of chromosomes (50 bivalents) compared with those of normal diploids (25 bivalents). Thus, the production of unreduced diploid spermatozoa is initiated by premeiotic endomitosis (or endoreduplication), chromosome doubling before meiosis, and is followed by two quasinormal divisions. Larger nuclei in the germ cells were observed in all stages of type B spermatogonia in the testes of the sex-reversed clones. In contrast, besides having larger type A spermatogonia, the sex-reversed clones also had the type A spermatogonia that were the same size as those of normal diploids. It follows that chromosome duplication causing unreduced spermatogenesis occurred in the type A spermatogonia. The presence of tetraploid type A and early type B spermatogonia, identified by labeling wi...Continue Reading

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Citations

Jun 27, 2014·General and Comparative Endocrinology·Samyra Maria dos Santos Nassif LacerdaLuiz Renato de França
Feb 21, 2013·The New Phytologist·Nico De Storme, Danny Geelen
Jan 7, 2015·Theriogenology·Martin PšeničkaIevgeniia Gazo
Apr 28, 2018·Biology of Reproduction·Viktoriia IegorovaTaiju Saito
Oct 4, 2019·Dose-response : a Publication of International Hormesis Society·L Dinithi C PeirisHarry D Moore
Jun 9, 2018·Chromosome Research : an International Journal on the Molecular, Supramolecular and Evolutionary Aspects of Chromosome Biology·Masamichi KurodaKatsutoshi Arai
Jul 27, 2021·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·Matthias StöckKarel Janko

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Methods Mentioned

BETA
flow cytometry

Software Mentioned

EXPO32
WinMDI

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