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Germ plasm provides clues on meiosis: the concerted action of germ plasm granules and mitochondria in gametogenesis of the clam Ruditapes philippinarum

Published online by Cambridge University Press:  07 December 2018

Arkadiy Reunov*
University of Ottawa Heart Institute, Electron Microscopy Laboratory, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada National Scientific Centre of Marine Biology, Laboratory of Cell Differentiation, Far Eastern Branch of Russian Academy of Sciences, Vladivostok, 690041, Russia
Yana Alexandrova
National Scientific Centre of Marine Biology, Laboratory of Cell Differentiation, Far Eastern Branch of Russian Academy of Sciences, Vladivostok, 690041, Russia
Yulia Reunova
National Scientific Centre of Marine Biology, Laboratory of Cell Differentiation, Far Eastern Branch of Russian Academy of Sciences, Vladivostok, 690041, Russia
Alina Komkova
National Scientific Centre of Marine Biology, Laboratory of Cell Differentiation, Far Eastern Branch of Russian Academy of Sciences, Vladivostok, 690041, Russia
Liliana Milani
University of Bologna, Department of Biological, Geological and Environmental Sciences, Via Selmi 3, 40126 Bologna, Italy
Address for correspondence: Arkadiy Reunov. Electron Microscopy Laboratory, University of Ottawa Heart Institute, 40 Ruskin St, Ottawa ON K1Y 4W7, Canada. Tel: +1 613 761 5282. Fax: +1 613 761 4998. E-mail:


Germ plasm-related structures (GPRS) are known to accompany meiotic cell differentiation but their dynamics are still poorly understood. In this study, we analyzed the ultrastructural mechanisms of GPRS transformation during oogenesis and spermatogenesis of the bivalve mollusc Ruditapes philippinarum (Manila clam), exploring patterns of GPRS activity occurring at meiosis onset, sex-specific difference/similarity of such patterns, and the involvement of mitochondria during GPRS-assigned events. In the two sexes, the zygotene–pachytene stage of meiosis is anticipated by three shared steps. First, the dispersion of germ plasm granules containing the germ line determinant VASA occurs. Second, the VASA protein deriving from germ plasm granules enters neighbouring mitochondria and appears to induce mitochondrial matter release, as supported by cytochrome B localization outside the mitochondria. Third, intranuclear VASA entrance occurs and the protein appears involved in chromatin reorganization, as supported by VASA localization in synaptonemal complexes. In spermatogenesis, these three steps are sufficient for the normal course of meiosis. In oogenesis, these are followed by the action of ‘germ plasm granule formation complex’, a novel type of structure that appears alternative to the Balbiani body. The possibility of germ plasm involvement in reproductive technologies is also suggested.

Research Article
© Cambridge University Press 2018 

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