Editing Mutagenesis (section)

===Adaptive mutagenesis mechanisms===
{{Main|Adaptive mutation}}

Adaptive mutagenesis has been defined as mutagenesis mechanisms that enable an organism to adapt to an environmental stress. Since the variety of environmental stresses is very broad, the mechanisms that enable it are also quite broad, as far as research on the field has shown. For instance, in bacteria, while modulation of the SOS response and endogenous prophage DNA synthesis has been shown to increase ''Acinetobacter baumannii'' resistance to ciprofloxacin.<ref name="Geisinger" /> Resistance mechanisms are presumed to be linked to chromosomal mutation untransferable via [[horizontal gene transfer]] in some members of family Enterobacteriaceae, such as ''E. coli, Salmonella'' spp., ''Klebsiella'' spp., and ''Enterobacter'' spp.<ref>{{Cite journal|last1=Aghapour|first1=Zahra|last2=Gholizadeh|first2=Pourya|last3=Ganbarov|first3=Khudaverdi|last4=bialvaei|first4=Abed Zahedi|last5=Mahmood|first5=Suhad Saad|last6=Tanomand|first6=Asghar|last7=Yousefi|first7=Mehdi|last8=Asgharzadeh|first8=Mohammad|last9=Yousefi|first9=Bahman|date=April 2019|title=Molecular mechanisms related to colistin resistance in Enterobacteriaceae|journal=Infection and Drug Resistance|volume= 12|pages=965–975|doi=10.2147/idr.s199844|pmid=31190901|pmc=6519339 |doi-access=free }}</ref> Chromosomal events, specially gene amplification, seem also to be relevant to this adaptive mutagenesis in bacteria.<ref>{{Cite journal|last1=Hersh|first1=Megan N|last2=Ponder|first2=Rebecca G|last3=Hastings|first3=P.J|last4=Rosenberg|first4=Susan M|date=June 2004|title=Adaptive mutation and amplification in Escherichia coli: two pathways of genome adaptation under stress|journal=Research in Microbiology|volume=155|issue=5|pages=352–359|doi=10.1016/j.resmic.2004.01.020|pmid=15207867|doi-access=free}}</ref>

Research in eukaryotic cells is much scarcer, but chromosomal events seem also to be rather relevant: while an ectopic intrachromosomal recombination has been reported to be involved in acquisition of resistance to 5-fluorocytosine in ''Saccharomyces cerevisiae'',<ref name=":0" /> genome duplications have been found to confer resistance in ''S. cerevisiae'' to nutrient-poor environments.<ref name=":1" /><ref>{{Cite journal|last1=Longerich|first1=S.|last2=Galloway|first2=A. M.|last3=Harris|first3=R. S.|last4=Wong|first4=C.|last5=Rosenberg|first5=S. M.|date=1995-12-19|title=Adaptive mutation sequences reproduced by mismatch repair deficiency.|journal=Proceedings of the National Academy of Sciences|volume=92|issue=26|pages=12017–12020|doi=10.1073/pnas.92.26.12017|issn=0027-8424|pmc=40287|pmid=8618835|bibcode=1995PNAS...9212017L|doi-access=free}}</ref><ref>{{Cite journal|last1=Rosenberg|first1=Susan M.|last2=Fitzgerald|first2=Devon M.|date=2019-04-01|title=What is mutation? A chapter in the series: How microbes "jeopardize" the modern synthesis|journal=PLOS Genetics|volume=15|issue=4|pages=e1007995|doi=10.1371/journal.pgen.1007995|pmid=30933985|pmc=6443146|issn=1553-7404 |doi-access=free }}</ref>