Genome plasticity in response to stress in Tetrahymena thermophila: selective and reversible chromosome amplification and paralogous expansion of metallothionein genes.

ABSTRACT: Extreme stress situations can induce genetic variations including genome reorganization. In ciliates like Tetrahymena thermophila, the approximately 45-fold ploidy of the somatic macronucleus may enable adaptive responses that depend on genome plasticity. To identify potential genome-level adaptations related to metal toxicity, we isolated three Tetrahymena thermophila strains after an extended adaptation period to extreme metal concentrations (Cd²⁺ , Cu²⁺ or Pb²⁺ ). In the Cd-adapted strain, we found a approximately five-fold copy number increase of three genes located in the same macronuclear chromosome, including two metallothionein genes, MTT1 and MTT3. The apparent amplification of this macronuclear chromosome was reversible and reproducible, depending

SUBMITTER: de Francisco P 

PROVIDER: S-EPMC6117198 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature