PMID- 29687579
OWN - NLM
STAT- MEDLINE
DCOM- 20190926
LR  - 20200306
IS  - 1462-2920 (Electronic)
IS  - 1462-2912 (Print)
IS  - 1462-2912 (Linking)
VI  - 20
IP  - 7
DP  - 2018 Jul
TI  - Genome plasticity in response to stress in Tetrahymena thermophila: selective and 
      reversible chromosome amplification and paralogous expansion of metallothionein 
      genes.
PG  - 2410-2421
LID - 10.1111/1462-2920.14251 [doi]
AB  - 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 (Cd(2+) , 
      Cu(2+) or Pb(2+) ). 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 on the 
      presence of environmental metal. We also analysed three knockout (KO) and/or 
      knockdown (KD) strains for MTT1 and/or MTT5. In the MTT5KD strain, we found at 
      least two new genes arising from paralogous expansion of MTT1, which encode 
      truncated variants of MTT1. The expansion can be explained by a model based on 
      somatic recombination between MTT1 genes on pairs of macronuclear chromosomes. At 
      least two of the new paralogs are transcribed and upregulated in response to 
      Cd(2+) . Altogether, we have thus identified two distinct mechanisms, both 
      involving genomic plasticity in the polyploid macronucleus that may represent 
      adaptive responses to metal-related stress.
CI  - (c) 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.
FAU - de Francisco, Patricia
AU  - de Francisco P
AD  - Departamento Genetica, Fisiologia y Microbiologia, Facultad de Biologia, 
      Universidad Complutense de Madrid (UCM). C/. Jose Antonio Novais, 12. 28040 
      Madrid, Spain.
FAU - Martin-Gonzalez, Ana
AU  - Martin-Gonzalez A
AD  - Departamento Genetica, Fisiologia y Microbiologia, Facultad de Biologia, 
      Universidad Complutense de Madrid (UCM). C/. Jose Antonio Novais, 12. 28040 
      Madrid, Spain.
FAU - Turkewitz, Aaron P
AU  - Turkewitz AP
AD  - Department of Molecular Genetics and Cell Biology, Cummings Life Science Center, 
      University of Chicago. 920 East 58th Street, Chicago, IL 60637, USA.
FAU - Gutierrez, Juan Carlos
AU  - Gutierrez JC
AUID- ORCID: 0000-0003-0909-3349
AD  - Departamento Genetica, Fisiologia y Microbiologia, Facultad de Biologia, 
      Universidad Complutense de Madrid (UCM). C/. Jose Antonio Novais, 12. 28040 
      Madrid, Spain.
LA  - eng
GR  - R01 GM105783/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, Non-U.S. Gov't
DEP - 20180522
PL  - England
TA  - Environ Microbiol
JT  - Environmental microbiology
JID - 100883692
RN  - 9038-94-2 (Metallothionein)
SB  - IM
MH  - Adaptation, Physiological
MH  - Animals
MH  - Chromosomes
MH  - *Genome, Protozoan
MH  - Metallothionein/*genetics/metabolism
MH  - Stress, Physiological
MH  - Tetrahymena thermophila/*genetics/physiology
MH  - Up-Regulation
PMC - PMC6117198
MID - NIHMS963988
COIS- Conflict of Interest The authors declare no conflict of interests.
EDAT- 2018/04/25 06:00
MHDA- 2019/09/27 06:00
PMCR- 2019/07/01
CRDT- 2018/04/25 06:00
PHST- 2018/04/18 00:00 [received]
PHST- 2018/04/18 00:00 [accepted]
PHST- 2018/04/25 06:00 [pubmed]
PHST- 2019/09/27 06:00 [medline]
PHST- 2018/04/25 06:00 [entrez]
PHST- 2019/07/01 00:00 [pmc-release]
AID - 10.1111/1462-2920.14251 [doi]
PST - ppublish
SO  - Environ Microbiol. 2018 Jul;20(7):2410-2421. doi: 10.1111/1462-2920.14251. Epub 
      2018 May 22.