Abstract
The first mitosis of the mammalian embryo must partition the parental genomes contained in two pronuclei. In rodent zygotes, sperm centrosomes are degraded, and instead, acentriolar microtubule organizing centers and microtubule self-organization guide the assembly of two separate spindles around the genomes. In nonrodent mammals, including human or bovine, centrosomes are inherited from the sperm and have been widely assumed to be active. Whether nonrodent zygotes assemble a single centrosomal spindle around both genomes or follow the dual spindle self-assembly pathway is unclear. To address this, we investigated spindle assembly in bovine zygotes by systematic immunofluorescence and real-time light-sheet microscopy. We show that two independent spindles form despite the presence of centrosomes, which had little effect on spindle structure and were only loosely connected to the two spindles. We conclude that the dual spindle assembly pathway is conserved in nonrodent mammals. This could explain whole parental genome loss frequently observed in blastomeres of human IVF embryos.
Original language | English |
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Article number | e202010106 |
Pages (from-to) | 1-24 |
Number of pages | 24 |
Journal | Journal of Cell Biology |
Volume | 220 |
Issue number | 11 |
DOIs | |
Publication status | Published - 1 Nov 2021 |
Bibliographical note
Funding Information:Confocal microscopy images were acquired at the Centre for Cellular Imaging at the Faculty of Veterinary Medicine, Utrecht. The authors would like to thank Richard Wubbolts and Esther van?t Veld from the Centre for Cellular Imaging for their help and technical assistance in image acquisition. We also thank Christian Tischer from the Center for Bioimage Analysis at European Molecular Biology Laboratory (EMBL) for vital support with automated image processing, Petr Strnad for the development of the inverted light-sheet microscope, and Yu Lin, Lars Hufnagel, and Balint Balazs for maintenance and software modifications. The authors would like to thank Claudia Deelen, Ainhoa Larreategui, Radyon Huggins, Anouk Klein Kranenbarg, and Romy Timmer for their assistance with IVF and IF staining. The authors would also like to thank Andrea Genthner and Klaus Schmitt for assistance on the transport and work with bovine COCs at EMBL Heidelberg. The authors also thank Nathalie Daigle and Tomoya Kitajima for cloning of the DNA constructs that were used as templates for mRNA synthesis in this study. We thank Judith Reichmann and Manuel Eguren for helpful scientific discussions, and we also thank the whole Ellenberg Lab at EMBL and the IVF Lab of the Faculty of Veterinary Medicine in Utrecht for collegial support. We thank Franziska Kundel for reading the manuscript and Stephanie Alexander for organizational support. This work was supported by funds from the European Research Council (ERC advanced grant COREMA, grant agreement 694236 to J. Ellenberg and the EMBL). I. Schneider was supported by a Boehringer Ingelheim Fonds PhD fellowship and M. de Ruijter-Villani by an EMBO short-term fellowship for this project. J. Ellenberg is scientific co-founder and advisor of Luxendo (part of Bruker), which makes light-sheet?based microscopes commercially available. The remaining authors declare no competing financial interests. Author contributions: J. Ellenberg, M. de Ruijter-Villani, and I. Schneider conceived the project. I. Schneider and M. de Ruijter-Villani further designed and conducted the experiments and wrote the original draft of the manuscript. M.J. Hossain, I. Schneider, and M. de Ruijter-Villani performed the formal analysis. T.A.E. Stout contributed to conception of the work and edited the manuscript. J. Ellenberg supervised the project and reviewed and edited the manuscript. All authors contributed to the interpretation of the data and read and approved the final manuscript.
Funding Information:
This work was supported by funds from the European Research Council (ERC advanced grant COREMA, grant agreement 694236 to J. Ellenberg and the EMBL). I. Schneider was supported by a Boehringer Ingelheim Fonds PhD fellowship and M. de Ruijter-Villani by an EMBO short-term fellowship for this project.
Publisher Copyright:
© 2021 Schneider et al.