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Adaptive response to DNA-damaging agents in natural Saccharomyces cerevisiae populations from "Evolution Canyon", Mt. Carmel, Israel.

Lidzbarsky GA, Shkolnik T, Nevo E - PLoS ONE (2009)

Bottom Line: Carmel, Israel).We exposed our strains to the different DNA-damaging agents and measured survival by counting colony forming units.The strains from the "African" slope were more resilient to both UVA and MMS than the strains from the "European" slope.

View Article: PubMed Central - PubMed

Affiliation: Institute of Evolution, Department of Evolutionary and Environmental Biology, Faculty of Science and Science Education, University of Haifa, Haifa, Israel.

ABSTRACT

Background: Natural populations of most organisms, especially unicellular microorganisms, are constantly exposed to harsh environmental factors which affect their growth. UV radiation is one of the most important physical parameters which influences yeast growth in nature. Here we used 46 natural strains of Saccharomyces cerevisiae isolated from several natural populations at the "Evolution Canyon" microsite (Nahal Oren, Mt. Carmel, Israel). The opposing slopes of this canyon share the same geology, soil, and macroclimate, but they differ in microclimatic conditions. The interslope differences in solar radiation (200%-800% more on the "African" slope) caused the development of two distinct biomes. The south-facing slope is sunnier and has xeric, savannoid "African" environment while the north-facing slope is represented by temperate, "European" forested environment. Here we studied the phenotypic response of the S. cerevisiae strains to UVA and UVC radiations and to methyl methanesulfonate (MMS) in order to evaluate the interslope effect on the strains' ability to withstand DNA-damaging agents.

Methodology/principal findings: We exposed our strains to the different DNA-damaging agents and measured survival by counting colony forming units. The strains from the "African" slope were more resilient to both UVA and MMS than the strains from the "European" slope. In contrast, we found that there was almost no difference between strains (with similar ploidy) from the opposite slopes, in their sensitivity to UVC radiation. These results suggest that the "African" strains are more adapted to higher solar radiation than the "European" strains. We also found that the tetraploids strains were more tolerant to all DNA-damaging agents than their neighboring diploid strains, which suggest that high ploidy level might be a mechanism of adaptation to high solar radiation.

Conclusions/significance: Our results and the results of parallel studies with several other organisms, suggest that natural selection appears to select, at a microscale, for adaptive complexes that can tolerate the higher UV radiation on the "African" slope.

Show MeSH
Pictures of “Evolution Canyon”.(A) A cross section of “Evolution Canyon” (lower Nahal Oren, Mt. Carmel). The right slope is the south-facing, “African”, xeric slope, and the left slope is the north-facing, “European”, temperate slope. The numbers represent the populations (sites). (B) An air-view of the canyon. The dark area is the “European” forested slope; the light area is the “African” savannoid slope.
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pone-0005914-g001: Pictures of “Evolution Canyon”.(A) A cross section of “Evolution Canyon” (lower Nahal Oren, Mt. Carmel). The right slope is the south-facing, “African”, xeric slope, and the left slope is the north-facing, “European”, temperate slope. The numbers represent the populations (sites). (B) An air-view of the canyon. The dark area is the “European” forested slope; the light area is the “African” savannoid slope.

Mentions: Forty-six S. cerevisiae strains (Table S1) were isolated from seven populations (sites) across the two slopes of “Evolution Canyon” (Fig. 1). Isolation and physiological identification was done by Nagornaya S. et al. in 2003 [22]. Further molecular identification and the determination of ploidy levels, was done by Katz-Ezov et al. in 2006 [12]. Collection sites are numbered 1–7; sites 1, 2, and 3 (AS1, AS2, and AS3) are located on the tropical, xeric, and savannoid “African” slope (AS), and sites 5, 6, and 7 (ES5, ES6, and ES7) are located on the temperate, mesic, and forested “European” slope (ES). A commercial lab strain, S288C [23] was used as a control. Strains were grown on liquid and solid YPD (2% glucose, 2% peptone, 1% yeast extract); 2% agar was added to solid media.


Adaptive response to DNA-damaging agents in natural Saccharomyces cerevisiae populations from "Evolution Canyon", Mt. Carmel, Israel.

Lidzbarsky GA, Shkolnik T, Nevo E - PLoS ONE (2009)

Pictures of “Evolution Canyon”.(A) A cross section of “Evolution Canyon” (lower Nahal Oren, Mt. Carmel). The right slope is the south-facing, “African”, xeric slope, and the left slope is the north-facing, “European”, temperate slope. The numbers represent the populations (sites). (B) An air-view of the canyon. The dark area is the “European” forested slope; the light area is the “African” savannoid slope.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2690839&req=5

pone-0005914-g001: Pictures of “Evolution Canyon”.(A) A cross section of “Evolution Canyon” (lower Nahal Oren, Mt. Carmel). The right slope is the south-facing, “African”, xeric slope, and the left slope is the north-facing, “European”, temperate slope. The numbers represent the populations (sites). (B) An air-view of the canyon. The dark area is the “European” forested slope; the light area is the “African” savannoid slope.
Mentions: Forty-six S. cerevisiae strains (Table S1) were isolated from seven populations (sites) across the two slopes of “Evolution Canyon” (Fig. 1). Isolation and physiological identification was done by Nagornaya S. et al. in 2003 [22]. Further molecular identification and the determination of ploidy levels, was done by Katz-Ezov et al. in 2006 [12]. Collection sites are numbered 1–7; sites 1, 2, and 3 (AS1, AS2, and AS3) are located on the tropical, xeric, and savannoid “African” slope (AS), and sites 5, 6, and 7 (ES5, ES6, and ES7) are located on the temperate, mesic, and forested “European” slope (ES). A commercial lab strain, S288C [23] was used as a control. Strains were grown on liquid and solid YPD (2% glucose, 2% peptone, 1% yeast extract); 2% agar was added to solid media.

Bottom Line: Carmel, Israel).We exposed our strains to the different DNA-damaging agents and measured survival by counting colony forming units.The strains from the "African" slope were more resilient to both UVA and MMS than the strains from the "European" slope.

View Article: PubMed Central - PubMed

Affiliation: Institute of Evolution, Department of Evolutionary and Environmental Biology, Faculty of Science and Science Education, University of Haifa, Haifa, Israel.

ABSTRACT

Background: Natural populations of most organisms, especially unicellular microorganisms, are constantly exposed to harsh environmental factors which affect their growth. UV radiation is one of the most important physical parameters which influences yeast growth in nature. Here we used 46 natural strains of Saccharomyces cerevisiae isolated from several natural populations at the "Evolution Canyon" microsite (Nahal Oren, Mt. Carmel, Israel). The opposing slopes of this canyon share the same geology, soil, and macroclimate, but they differ in microclimatic conditions. The interslope differences in solar radiation (200%-800% more on the "African" slope) caused the development of two distinct biomes. The south-facing slope is sunnier and has xeric, savannoid "African" environment while the north-facing slope is represented by temperate, "European" forested environment. Here we studied the phenotypic response of the S. cerevisiae strains to UVA and UVC radiations and to methyl methanesulfonate (MMS) in order to evaluate the interslope effect on the strains' ability to withstand DNA-damaging agents.

Methodology/principal findings: We exposed our strains to the different DNA-damaging agents and measured survival by counting colony forming units. The strains from the "African" slope were more resilient to both UVA and MMS than the strains from the "European" slope. In contrast, we found that there was almost no difference between strains (with similar ploidy) from the opposite slopes, in their sensitivity to UVC radiation. These results suggest that the "African" strains are more adapted to higher solar radiation than the "European" strains. We also found that the tetraploids strains were more tolerant to all DNA-damaging agents than their neighboring diploid strains, which suggest that high ploidy level might be a mechanism of adaptation to high solar radiation.

Conclusions/significance: Our results and the results of parallel studies with several other organisms, suggest that natural selection appears to select, at a microscale, for adaptive complexes that can tolerate the higher UV radiation on the "African" slope.

Show MeSH