Dual spindles assemble in bovine zygotes despite the presence of paternal centrosomes

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 th...

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Published inThe Journal of cell biology Vol. 220; no. 11; p. 1
Main Authors Schneider, Isabell, de Ruijter-Villani, Marta, Hossain, M Julius, Stout, Tom A E, Ellenberg, Jan
Format Journal Article
LanguageEnglish
Published United States Rockefeller University Press 01.11.2021
Subjects
Animals
Blastomeres
Cattle
Cell Cycle and Division
Centrosome - physiology
Centrosomes
Cytoskeleton
Development
Embryo, Mammalian - physiology
Embryos
Genome - physiology
Genomes
Immunofluorescence
Light sheets
Male
Mammals
Microtubule-Organizing Center - physiology
Microtubules - physiology
Mitosis
Mitosis - physiology
Self-assembly
Signal Transduction - physiology
Sperm
Spermatozoa - physiology
Spindle Apparatus - physiology
Spindles
Zygote - physiology
Zygotes
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Summary: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.
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I. Schneider and M. de Ruijter-Villani contributed equally to this paper.
ISSN:0021-9525
1540-8140
1540-8140
DOI:10.1083/jcb.202010106