Cosegregation of asymmetric features during cell division.

Silje Anda,Erik Boye,Beata Grallert,Kay Oliver Schink

doi:10.1098/rsob.210116

Abstract

Cellular asymmetry plays a major role in the ageing and evolution of multicellular organisms. However, it remains unknown how the cell distinguishes 'old' from 'new' and whether asymmetry is an attribute of highly specialized cells or a feature inherent in all cells. Here, we investigate the segregation of three asymmetric features: old and new DNA, the spindle pole body (SPB, the centrosome analogue) and the old and new cell ends, using a simple unicellular eukaryote, Schizosaccharomyces pombe. To our knowledge, this is the first study exploring three asymmetric features in the same cells. We show that of the three chromosomes of S. pombe, chromosome I containing the new parental strand, preferentially segregated to the cells inheriting the old cell end. Furthermore, the new SPB also preferentially segregated to the cells inheriting the old end. Our results suggest that the ability to distinguish 'old' from 'new' and to segregate DNA asymmetrically are inherent features even in simple unicellular eukaryotes.

Highlights

Asymmetry plays a key role in both uni- and multicellular organisms, establishing a wide range of features from uneven distribution of ageing factors between mother and daughter cells in Saccharomyces cerevisiae to the establishment of separate cell lineages during development in multicellular organisms [1]
To be able to synchronize the cells in G1 phase we introduced a temperature-sensitive cdc10 mutation
Using this strain the fate of the chromosomes and the spindle pole body (SPB) can be followed in single cells released from G1 and proceeding to generate mycelia with four granddaughter cells

Summary

Introduction

Asymmetry plays a key role in both uni- and multicellular organisms, establishing a wide range of features from uneven distribution of ageing factors between mother and daughter cells in Saccharomyces cerevisiae to the establishment of separate cell lineages during development in multicellular organisms [1]. Multicellularity has arisen several times in the course of evolution [2], and asymmetric cell divisions are prerequisite for most forms of multicellularity (when it involves specialization). A demonstration of asymmetric sister chromatid segregation is technically challenging and even separate studies on the same type of tissues have provided opposite results [13,14,15,16,17]. This has led to a long-standing debate about both the occurrence and mechanisms behind asymmetric DNA segregation [18,19]

Methods

Results

Conclusion