Organelle Volume Facilitates Spindle Positioning During C. elegans Female Meiosis

Abstract

Cortical positioning of oocyte meiotic spindles is required for reducing chromosome number by segregating chromosomes into polar bodies. In C. elegans, kinesin-1 transports membrane-bound organelles inward into a central ball that is hypothesized to push the meiotic spindle outward. Using focused ion beam scanning electron microscopy, we found that the percent volume occupied by membrane-bound organelles was 28% in a mature oocyte that has completed endocytosis of the yolk precursor, vitellogenin, compared to 17% in a less mature oocyte that has not yet endocytosed vitellogenin. We therefore hypothesized that blocking endocytosis of vitellogenin would reduce the size of the central ball of organelles packed inward by kinesin-1 and limit outward movement of the spindle. Depletion of vitellogenin or proteins required for endocytosis resulted in a smaller central volume of kinesin-coated organelles and defective spindle positioning. A computer simulation of a simple exclusion model faithfully recapitulated wildtype and mutant spindle position phenotypes. These results support a volume exclusion model for positioning acentriolar meiotic spindles.

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BibTeX RIS

BibTeX

@misc{lazureanu2026organelle,
  title = {{Organelle Volume Facilitates Spindle Positioning During C. elegans Female Meiosis}},
  author = {D. G. Lazureanu and E. Krueger and W. Qiu and A. A. Kopley-Smith and C. S. Smith and N. Voloshchuk and D. B. Cortes and M. Park and K. Uryu and M. Silva and E. Trautman and M. Innerberger and S. Preibisch and R. Vaxenburg and A. K. Stark and C. K. E. Bleck and M. Reilly and M. C. Wang and H. Shroff and F. J. McNally},
  howpublished = {bioRxiv},
  year = {2026},
  month = oct,
  doi = {10.64898/2026.10.07.757430},
  url = {https://www.biorxiv.org/content/10.64898/2026.10.07.757430v1},
  note = {CC BY},
}

RIS

TY  - UNPB
TI  - Organelle Volume Facilitates Spindle Positioning During C. elegans Female Meiosis
AU  - D. G. Lazureanu
AU  - E. Krueger
AU  - W. Qiu
AU  - A. A. Kopley-Smith
AU  - C. S. Smith
AU  - N. Voloshchuk
AU  - D. B. Cortes
AU  - M. Park
AU  - K. Uryu
AU  - M. Silva
AU  - E. Trautman
AU  - M. Innerberger
AU  - S. Preibisch
AU  - R. Vaxenburg
AU  - A. K. Stark
AU  - C. K. E. Bleck
AU  - M. Reilly
AU  - M. C. Wang
AU  - H. Shroff
AU  - F. J. McNally
PY  - 2026
DA  - 2026/10/07
PB  - bioRxiv
DO  - 10.64898/2026.10.07.757430
UR  - https://www.biorxiv.org/content/10.64898/2026.10.07.757430v1
AB  - Cortical positioning of oocyte meiotic spindles is required for reducing chromosome number by segregating chromosomes into polar bodies. In C. elegans, kinesin-1 transports membrane-bound organelles inward into a central ball that is hypothesized to push the meiotic spindle outward. Using focused ion beam scanning electron microscopy, we found that the percent volume occupied by membrane-bound organelles was 28% in a mature oocyte that has completed endocytosis of the yolk precursor, vitellogenin, compared to 17% in a less mature oocyte that has not yet endocytosed vitellogenin. We therefore hypothesized that blocking endocytosis of vitellogenin would reduce the size of the central ball of organelles packed inward by kinesin-1 and limit outward movement of the spindle. Depletion of vitellogenin or proteins required for endocytosis resulted in a smaller central volume of kinesin-coated organelles and defective spindle positioning. A computer simulation of a simple exclusion model faithfully recapitulated wildtype and mutant spindle position phenotypes. These results support a volume exclusion model for positioning acentriolar meiotic spindles.
ER  -

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