High-throughput measurement of recombination rates and genetic interference in Saccharomyces cerevisiae

Yeast ◽  
2018 ◽  
Vol 35 (6) ◽  
pp. 431-442 ◽  
Author(s):  
Xavier Raffoux ◽  
Mickael Bourge ◽  
Fabrice Dumas ◽  
Olivier C. Martin ◽  
Matthieu Falque
2018 ◽  
Author(s):  
Xavier Raffoux ◽  
Mickael Bourge ◽  
Fabrice Dumas ◽  
Olivier C. Martin ◽  
Matthieu Falque

ABSTRACTMeiotic recombination is a major driver of genome evolution by creating new genetic combinations. To probe the factors driving variability of meiotic recombination, we used a high-throughput method to measure recombination rates in 26 S. cerevisiae strains from different geographic origins and habitats. Fourteen intervals were monitored for each strain, covering chromosomes VI and XI entirely, and part of chromosome I. We found an average number of crossovers per chromosome ranging between 1.0 and 9.5 across strains (“domesticated” or not), which is higher than the average between 0.5 and 1.5 found in most organisms. In the different intervals analyzed, recombination showed up to 9-fold variation across strains but global recombination landscapes along chromosomes varied less. We also built an incomplete diallel experiment to measure recombination rates in one region of chromosome XI in 10 different crosses involving five parental strains. Our overall results indicate that recombination rate is increasingly positively correlated with sequence similarity between homologs (i) in DSB rich regions within intervals, (ii) in entire intervals, and (iii) at the whole genome scale. Therefore, these correlations cannot be explained by cis-effects only. In addition, by using a quantitative genetics analysis, we identified an inbreeding effect that reduces recombination rate in homozygous genotypes while other interaction effects (specific combining ability) or additive effects (general combining ability) are found to be weak. Finally, we measured significant crossover interference in some strains, and interference intensity was positively correlated with crossover number.Author SummaryMeiosis is a key process for sexually reproducing organisms by producing gametes with a halved set of genetic material. An essential step of meiosis is the formation of crossovers which are reciprocal exchanges of genetic material between chromosomes inherited from both parents. Crossovers ensure proper chromosome segregation and thus viable gametes. They also create novel genetic diversity which contributes to evolution and permits genetic improvement of agriculturally important species. Most living organisms produce between one and three crossovers per chromosome, and tight regulatory mechanisms control the number of crossovers and their distribution along chromosomes. In spite of their potential importance for biotechnological applications, such mechanisms are still poorly understood.Using a high throughput method based on fluorescent markers, we investigated the diversity of recombination in the budding yeast Saccharomyces cerevisiae. We observed up to 9-fold differences in numbers of crossovers across hybrids obtained by crossing different strains with a common tester, and this variation was correlated with the degree of DNA sequence similarity between homologous chromosomes. By also investigating homozygotes, we conclude that on the one hand too much sequence divergence impairs recombination in distantly-related hybrids, and on the other hand complete homozygosity is also associated with lower numbers of crossovers.


Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 21-34
Author(s):  
C W Moore ◽  
D M Hampsey ◽  
J F Ernst ◽  
F Sherman

Abstract Recombination rates have been examined in two-point crosses of various defined cyc1 mutations that cause the loss or nonfunction of iso-1-cytochrome c in the yeast Saccharomyces cerevisiae. Recombinants arising by three different means were investigated, including X-ray induced mitotic recombination, spontaneous mitotic recombination, and meiotic recombination. Heteroallelic diploid strains were derived by crossing cyc1 mutants containing a series of alterations at or near the same site to cyc1 mutants containing alterations at various distances. Marked disproportionalities between physical distances and recombination frequencies were observed with certain cyc1 mutations, indicating that certain mismatched bases can significantly affect recombination. The marker effects were more pronounced when the two mutational sites of the heteroalleles were within about 20 base pairs, but separated by at least 4 base pairs. Two alleles, cyc1-163 and cyc1-166, which arose by G.C----C.G transversions at nucleotide positions 3 and 194, respectively, gave rise to especially high rates of recombination. Other mutations having different substitutions at the same nucleotide positions were not associated with abnormally high recombination frequencies. We suggest that these marker effects are due to the lack of repair of either G/G or C/C mismatched base pairs, while the other mismatched base pair of the heteroallele undergoes substantial repair. Furthermore, we suggest that diminished recombination frequencies are due to the concomitant repair of both mismatches within the same DNA tract.


2021 ◽  
Vol 2 ◽  
Author(s):  
Marco Eigenfeld ◽  
Roland Kerpes ◽  
Thomas Becker

In yeast, aging is widely understood as the decline of physiological function and the decreasing ability to adapt to environmental changes. Saccharomyces cerevisiae has become an important model organism for the investigation of these processes. Yeast is used in industrial processes (beer and wine production), and several stress conditions can influence its intracellular aging processes. The aim of this review is to summarize the current knowledge on applied stress conditions, such as osmotic pressure, primary metabolites (e.g., ethanol), low pH, oxidative stress, heat on aging indicators, age-related physiological changes, and yeast longevity. There is clear evidence that yeast cells are exposed to many stressors influencing viability and vitality, leading to an age-related shift in age distribution. Currently, there is a lack of rapid, non-invasive methods allowing the investigation of aspects of yeast aging in real time on a single-cell basis using the high-throughput approach. Methods such as micromanipulation, centrifugal elutriator, or biotinylation do not provide real-time information on age distributions in industrial processes. In contrast, innovative approaches, such as non-invasive fluorescence coupled flow cytometry intended for high-throughput measurements, could be promising for determining the replicative age of yeast cells in fermentation and its impact on industrial stress conditions.


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