Affected chromosome homeostasis and genomic instability of clonal yeast cultures

Abstract

Yeast cells originating from one single colony are considered genotypically and phenotypically identical. However, taking into account the cellular heterogeneity, it seems also important to monitor cell-to-cell variations within a clone population. In the present study, a comprehensive yeast karyotype screening was conducted using single chromosome comet assay. Chromosome-dependent and mutation-dependent changes in DNA (DNA with breaks or with abnormal replication intermediates) were studied using both single-gene deletion haploid mutants (bub1, bub2, mad1, tel1, rad1 and tor1) and diploid cells lacking one active gene of interest, namely BUB1/bub1, BUB2/bub2, MAD1/mad1, TEL1/tel1, RAD1/rad1 and TOR1/tor1 involved in the control of cell cycle progression, DNA repair and the regulation of longevity. Increased chromosome fragility and replication stress-mediated chromosome abnormalities were correlated with elevated incidence of genomic instability, namely aneuploid events—disomies, monosomies and to a lesser extent trisomies as judged by in situ comparative genomic hybridization (CGH). The tor1 longevity mutant with relatively balanced chromosome homeostasis was found the most genomically stable among analyzed mutants. During clonal yeast culture, spontaneously formed abnormal chromosome structures may stimulate changes in the ploidy state and, in turn, promote genomic heterogeneity. These alterations may be more accented in selected mutated genetic backgrounds, namely in yeast cells deficient in proper cell cycle regulation and DNA repair.

Tight Regulation of Srs2 Helicase Activity Is Crucial for Proper Functioning of DNA Repair Mechanisms

“…The HR reactions are catalyzed by members of the RAD52 epistasis group ( RAD51 , RAD52 , RAD54 , RAD55 , RAD57 , RAD59 ). Yeast cells mutated for these genes are defective in the repair of DNA damage caused by ionizing radiation and methyl methane sulfonate (MMS), in mitotic and meiotic recombination, and in mating-type switching [as double-stranded break (DSB) repair intermediates are involved in these processes] ( symington and gautier 2011 ; gao et al 2014 ; adamczyk et al 2016 ). Some of the group members are important for catalyzing only some of pathways mentioned above, while lacking a role in others.…”

How to characterize a strain? The neglected influence of clonal heterogeneity on the phenotypes of industrialSaccharomyces

“…In comparison, relatively few yeast studies have been devoted to the importance of clonal heterogeneity in adaptation (e.g. Holland et al 2014;Bódi et al 2017;Vázquez-García et al 2017) or to understanding how epigenetics, gene expression noise, metabolic state, unequal cell division, chronological or replicative age differences, or prions cause yeast populations to be heterogeneous (Halfmann et al 2012;Ackermann 2015;Adamczyk et al 2016;Cerulus et al 2016;Duveau et al 2018). The latter study areas, to our knowledge, exclusively focus on lab strains and not on industrial ones.…”

Insights into the Conserved Regulatory Mechanisms of Human and Yeast Aging

“…ERCC4 and ERCC1 are the yeast homologs of RAD1 and RAD10 respectively, and function in the DDR pathways. Similarly, a mutation in RAD1 and RAD10 causes genomic instability in yeast clonal cultures [114]. Not surprisingly, the deletion of DDR pathway genes was reported to decrease the lifespan of yeast [115].…”