Molecular signatures of aneuploidy-driven adaptive evolution

Area of Science:

• Genetics
• Evolutionary Biology
• Cell Biology

Background:

• Aneuploidy, an alteration in normal chromosome number, presents a paradox: it can impair cell function yet also drive adaptation.
• The mechanisms by which cells develop tolerance to aneuploidy are not fully understood.

Purpose of the Study:

• To investigate how yeast cells develop tolerance to aneuploidy through long-term experimental evolution.
• To characterize the genetic and molecular strategies employed by aneuploid cells to adapt and survive.

Main Methods:

• Subjecting disomic yeast strains (carrying an extra chromosome) to long-term experimental evolution under strong selection.
• Forcing disomy maintenance and daily population dilution.
• Characterizing mutations, karyotype alterations, and gene expression changes.

Main Results:

• Yeast strains with different extra chromosomes exhibited varying mutation rates and adaptive events.
• Cells evolved towards normal ploidy via chromosomal DNA loss and gene expression modifications.
• Recurrent mutations and altered gene expression were identified, including a variant enhancing growth under genotoxic stress.

Conclusions:

• Disomic yeast strains demonstrate rapid evolvability, adapting through genetic and molecular changes.
• These adaptable aneuploid strains can serve as models for studying mutation fitness effects under diverse stress conditions.