Mechanisms that prevent catastrophic interactions between paternal chromosomes and the oocyte meiotic spindle

Abstract

Meiosis produces haploid gametes by accurately reducing chromosome ploidy through one round of DNA replication and two subsequent rounds of chromosome segregation and cell division. The cell divisions of female meiosis are highly asymmetric and give rise to a large egg and two very small polar bodies that do not contribute to development. These asymmetric divisions are driven by meiotic spindles that are small relative to the size of the egg and have one pole juxtaposed against the cell cortex to promote polar body extrusion. An additional unique feature of female meiosis is that fertilization occurs before extrusion of the second polar body in nearly all animal species. Thus sperm-derived chromosomes are present in the egg during female meiosis. Here, we explore the idea that the asymmetry of female meiosis spatially separates the sperm from the meiotic spindle to prevent detrimental interactions between the spindle and the paternal chromosomes.

DNA damage response signaling pathways and targets for radiotherapy sensitization in cancer

“…Cell cycle checkpoints, which define the end product of a molecular regulatory pathway or signaling cascade, ensure an ordered succession of cell cycle events, and when perturbed, lead to cell cycle arrest 198 ; these checkpoints are critical for protecting cells from progressing into the next phase of the cell cycle before prior molecular events, such as DNA damage and spindle structure disruption, have been resolved 199 . If premature entry into the next cell cycle phase occurs without checkpoint review, catastrophic consequences or cell death may occur 200 . Cell cycle arrest is caused by depletion of some key proteins regulating this process.…”

Katanin, kinesin-13 and ataxin-2 inhibit premature interaction between maternal and paternal genomes inC. eleganszygotes

“…When this mechanism was bypassed by injecting demembranated sperm adjacent to the spindle, the sperm DNA was ejected into a polar body (1). In C. elegans, the nucleus is positioned away from the site of future fertilization so that the meiosis I spindle assembles at the opposite end of the ellipsoid zygote from the site of fertilization (2)(3)(4).…”

Katanin, kinesin-13, and ataxin-2 inhibit premature interaction between maternal and paternal genomes in C. elegans zygotes

“…When this mechanism was bypassed by injecting demembranated sperm adjacent to the spindle, the sperm DNA was ejected into a polar body ( Mori et al, 2021 ). In C. elegans , the nucleus is positioned away from the site of future fertilization so that the meiosis I spindle assembles at the opposite end of the ellipsoid zygote from the site of fertilization ( Panzica and McNally, 2018 ; McNally et al, 2010 ; McCarter et al, 1999 ).…”