Editing Polyploidy (section)

=== Bacteria ===

Each ''[[Deinococcus radiodurans]]'' [[bacteria|bacterium]] contains 4-8 copies of its [[chromosome]].<ref name="pmid649572">{{cite journal | vauthors = Hansen MT | title = Multiplicity of genome equivalents in the radiation-resistant bacterium Micrococcus radiodurans | journal = Journal of Bacteriology | volume = 134 | issue = 1 | pages = 71–75 | date = April 1978 | pmid = 649572 | pmc = 222219 | doi = 10.1128/JB.134.1.71-75.1978 }}</ref> Exposure of ''D. radiodurans'' to [[X-ray]] irradiation or [[desiccation]] can shatter its [[genome]]s into hundred of short random fragments. Nevertheless, ''D. radiodurans'' is highly resistant to such exposures. The mechanism by which the genome is accurately restored involves RecA-mediated [[homologous recombination]] and a process referred to as extended [[synthesis-dependent strand annealing (SDSA)]].<ref name="pmid17006450">{{cite journal | vauthors = Zahradka K, Slade D, Bailone A, Sommer S, Averbeck D, Petranovic M, Lindner AB, Radman M | display-authors = 6 | title = Reassembly of shattered chromosomes in Deinococcus radiodurans | journal = Nature | volume = 443 | issue = 7111 | pages = 569–573 | date = October 2006 | pmid = 17006450 | doi = 10.1038/nature05160 | bibcode = 2006Natur.443..569Z }}</ref>

''[[Azotobacter vinelandii]]'' can contain up to 80 chromosome copies per cell.<ref name="pmid2785985">{{cite journal | vauthors = Nagpal P, Jafri S, Reddy MA, Das HK | title = Multiple chromosomes of Azotobacter vinelandii | journal = Journal of Bacteriology | volume = 171 | issue = 6 | pages = 3133–3138 | date = June 1989 | pmid = 2785985 | pmc = 210026 | doi = 10.1128/jb.171.6.3133-3138.1989 }}</ref> However this is only observed in fast growing cultures, whereas cultures grown in synthetic minimal media are not polyploid.<ref name="pmid8021173">{{cite journal | vauthors = Maldonado R, Jiménez J, Casadesús J | title = Changes of ploidy during the Azotobacter vinelandii growth cycle | journal = Journal of Bacteriology | volume = 176 | issue = 13 | pages = 3911–3919 | date = July 1994 | pmid = 8021173 | pmc = 205588 | doi = 10.1128/jb.176.13.3911-3919.1994 }}</ref>