Editing Mating system (section)

===Archaea===

In several species of [[archaea]], mating is mediated by formation of cellular aggregates.
''[[Halobacterium]] volcanii'', an extreme [[Halophile|halophilic]] archaeon, forms cytoplasmic bridges between cells that appear to be used for transfer of DNA from one cell to another in either direction.<ref name="pmid2818746">{{cite journal |vauthors=Rosenshine I, Tchelet R, Mevarech M |title=The mechanism of DNA transfer in the mating system of an archaebacterium |journal=Science |volume=245 |issue=4924 |pages=1387–9 |year=1989 |pmid=2818746 |doi= 10.1126/science.2818746|bibcode=1989Sci...245.1387R }}</ref>

When the [[Hyperthermophile|hyperthermophilic]] archaea ''[[Sulfolobus solfataricus]]''<ref name=Frol>{{cite journal |vauthors=Fröls S, Ajon M, Wagner M, Teichmann D, Zolghadr B, Folea M, Boekema EJ, Driessen AJ, Schleper C, Albers SV |title=UV-inducible cellular aggregation of the hyperthermophilic archaeon Sulfolobus solfataricus is mediated by pili formation |journal=Mol. Microbiol. |volume=70 |issue=4 |pages=938–52 |year=2008 |pmid=18990182 |doi=10.1111/j.1365-2958.2008.06459.x |url=https://www.rug.nl/research/portal/files/56956856/UV_inducible_cellular_aggregation_of_the_hyperthermophilic_archaeon_Sulfolobus_solfataricus_is_mediated_by_pili_formation.pdf|doi-access=free }}</ref> and ''[[Sulfolobus acidocaldarius]]''<ref name=Ajon>{{cite journal |vauthors=Ajon M, Fröls S, van Wolferen M, Stoecker K, Teichmann D, Driessen AJ, Grogan DW, Albers SV, Schleper C |title=UV-inducible DNA exchange in hyperthermophilic archaea mediated by type IV pili |journal=Mol. Microbiol. |volume=82 |issue=4 |pages=807–17 |year=2011 |pmid=21999488 |doi=10.1111/j.1365-2958.2011.07861.x |url=https://pure.rug.nl/ws/files/6771142/2011MolMicrobiolAjon.pdf|doi-access=free }}</ref> are exposed to the DNA damaging agents [[Ultraviolet|UV]] irradiation, [[bleomycin]] or [[Mitomycins|mitomycin C]], species-specific cellular aggregation is induced.  Aggregation in ''S. solfataricus'' could not be induced by other physical stressors, such as pH or temperature shift,<ref name=Frol /> suggesting that aggregation is induced specifically by DNA damage.  Ajon et al.<ref name=Ajon /> showed that UV-induced cellular aggregation mediates chromosomal marker exchange with high frequency in ''S. acidocaldarius''.  Recombination rates exceeded those of uninduced cultures by up to three orders of magnitude.  Frols et al.<ref name=Frol /> and Ajon et al.<ref name=Ajon /> hypothesized that cellular aggregation enhances species-specific DNA transfer between ''Sulfolobus'' cells in order to provide increased repair of damaged DNA by means of [[homologous recombination]]. This response appears to be a primitive form of sexual interaction similar to the more well-studied bacterial transformation systems that are also associated with species specific DNA transfer between cells leading to homologous recombinational repair of DNA damage.{{Citation needed|date=December 2019|reason=removed citation to predatory publisher content}}