A meiotic mystery: How sister kinetochores avoid being pulled in opposite directions during the first division.

Kim Nasmyth

doi:10.1002/bies.201500006

Abstract

We now take for granted that despite the disproportionate contribution of females to initial growth of their progeny, there is little or no asymmetry in the contribution of males and females to the eventual character of their shared offspring. In fact, this key insight was only established towards the end of the eighteenth century by Joseph Koelreuter's pioneering plant breeding experiments. If males and females supply equal amounts of hereditary material, then the latter must double each time an embryo is conceived. How then does the amount of this mysterious stuff not multiply exponentially from generation to generation? A compensatory mechanism for diluting the hereditary material must exist, one that ensures that if each parent contributes one half, each grandparent contributes a quarter, and each great grandparent merely an eighth. An important piece of the puzzle of how hereditary material is diluted at each generation has been elucidated over the past ten years.

Highlights

It is, widely appreciated that the replication and segregation of division is preceded by chromatid (DNA) molecules each time a cell divides forms the basis for most hereditary phenomena
If not all, cohesion is created during DNA replication, separase must remain inactive from S phase until the onset of anaphase, a process mediated by an inhibitory chaperone called securin and phosphorylation by cyclin B/Cdk1 [7]
The finding that monopolin contains two sites for binding Dsn1’s Csm1 interacting domain (CID) at each of the two vertices of its V-shaped Csm1/ Lrs4 subcomplex suggests that it might mediate co-orientation by crosslinking MIND complexes associated with different sister kinetochores, thereby forcing them to act as a single entity

Summary

Kim Nasmyth

We take for granted that despite the disproportionate contribution of females to initial growth of their progeny, there is little or no asymmetry in the contribution of males and females to the eventual character of their shared offspring. This key insight was only established towards the end of the eighteenth century by Joseph Koelreuter’s pioneering plant breeding experiments. A compensatory mechanism for diluting the hereditary material must exist, one that ensures that if each parent contributes one half, each grandparent contributes a quarter, and each great grandparent merely an eighth.

Introduction

Changes needed to convert mitosis to meiosis

Why is it so elaborate?

Inconsistencies awaiting resolution

Monopolin is not conserved

Conclusions and outlook