TY - JOUR
T1 - An integrated undergraduate laboratory exercise to demonstrate microbial evolution: petite mutants in Saccharomyces cerevisiae
AU - Qi, Qin
AU - Stacey, Jeremy
AU - Wright, Nureeni
AU - Tetu, Sasha
AU - Gillings, Michael
N1 - Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.
PY - 2024/2/1
Y1 - 2024/2/1
N2 - Understanding that evolution progresses through generation of DNA variants followed by selection is a key learning outcome for biology students. We designed an integrated and innovative undergraduate laboratory exercise using Saccharomyces cerevisiae to demonstrate these principles. Students perform in vitro experimental evolution by repeatedly propagating large or small yeast colonies on a weekly basis. Small-colony variants known as petites arise by mutations that disrupt aerobic respiration. To demonstrate the effects of increased mutation rates, half of the selection lines are exposed to ultraviolet irradiation. To understand how the petite phenotype arises, polymerase chain reaction (PCR) is performed to examine mitochondrial DNA, while biochemical assays are used to assess the ability of petites to undergo aerobic respiration. This exercise demonstrates evolution by artificial selection over a suitably short timeframe and links the results to a critical biochemical process: the role of mitochondria in aerobic respiration and ATP production. By implementing these experiments, we successfully demonstrated that the frequencies of petite mutants in evolved populations varied according to the selection pressure we applied, and that petite mutants carried deletions in mitochondrial DNA as anticipated. Through an integrated learning context, this practical exercise promotes fundamental understanding of evolutionary processes and fosters critical thinking skills.
AB - Understanding that evolution progresses through generation of DNA variants followed by selection is a key learning outcome for biology students. We designed an integrated and innovative undergraduate laboratory exercise using Saccharomyces cerevisiae to demonstrate these principles. Students perform in vitro experimental evolution by repeatedly propagating large or small yeast colonies on a weekly basis. Small-colony variants known as petites arise by mutations that disrupt aerobic respiration. To demonstrate the effects of increased mutation rates, half of the selection lines are exposed to ultraviolet irradiation. To understand how the petite phenotype arises, polymerase chain reaction (PCR) is performed to examine mitochondrial DNA, while biochemical assays are used to assess the ability of petites to undergo aerobic respiration. This exercise demonstrates evolution by artificial selection over a suitably short timeframe and links the results to a critical biochemical process: the role of mitochondria in aerobic respiration and ATP production. By implementing these experiments, we successfully demonstrated that the frequencies of petite mutants in evolved populations varied according to the selection pressure we applied, and that petite mutants carried deletions in mitochondrial DNA as anticipated. Through an integrated learning context, this practical exercise promotes fundamental understanding of evolutionary processes and fosters critical thinking skills.
KW - Experimental evolution
KW - Saccharomyces cerevisiae
KW - Aerobic respiration
KW - Mitochondrial DNA
KW - Molecular microbiology
UR - http://www.scopus.com/inward/record.url?scp=85187292603&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/45b434b4-8f0a-338a-a854-2cba78a7eaa4/
U2 - 10.1525/abt.2024.86.2.101
DO - 10.1525/abt.2024.86.2.101
M3 - Article
SN - 0002-7685
VL - 86
SP - 101
EP - 107
JO - The American Biology Teacher
JF - The American Biology Teacher
IS - 2
ER -