Editing Mating system (section)

===Bacteria===

Mating in [[bacteria]] involves transfer of DNA from one cell to another and incorporation of the transferred DNA into the recipient bacteria's [[genome]] by [[homologous recombination]].  Transfer of DNA between bacterial cells can occur in three main ways.  First, a bacterium can take up [[exogenous DNA]] released into the intervening medium from another bacterium by a process called [[Transformation (genetics)|'''transformation''']].  DNA can also be transferred from one bacterium to another by the process of [[Transduction (genetics)|'''transduction''']], which is mediated by an infecting virus (bacteriophage).  The third method of DNA transfer is [[Bacterial conjugation|''conjugation'']], in which a [[plasmid]] mediates transfer through direct cell contact between cells.

Transformation, unlike transduction or conjugation, depends on numerous bacterial gene products that specifically interact to perform this complex process,<ref name="pmid15083159">{{cite journal |vauthors=Chen I, Dubnau D |title=DNA uptake during bacterial transformation |journal=Nat. Rev. Microbiol. |volume=2 |issue=3 |pages=241–9 |year=2004 |pmid=15083159 |doi=10.1038/nrmicro844 |s2cid=205499369 }}</ref> and thus transformation is clearly a bacterial [[adaptation]] for DNA transfer.  In order for a bacterium to bind, take up and recombine donor DNA into its own chromosome, it must first enter a special physiological state termed [[natural competence]].  In ''[[Bacillus subtilis]]'' about 40 genes are required for the development of competence and DNA uptake.<ref name="pmid8901420">{{cite journal |vauthors=Solomon JM, Grossman AD |title=Who's competent and when: regulation of natural genetic competence in bacteria |journal=Trends Genet. |volume=12 |issue=4 |pages=150–5 |year=1996 |pmid=8901420 |doi= 10.1016/0168-9525(96)10014-7}}</ref>  The length of DNA transferred during ''B. subtilis'' transformation can be as much as a third and up to the whole chromosome.<ref name="pmid11388459">{{cite journal |vauthors=Akamatsu T, Taguchi H |title=Incorporation of the whole chromosomal DNA in protoplast lysates into competent cells of Bacillus subtilis |journal=Biosci. Biotechnol. Biochem. |volume=65 |issue=4 |pages=823–9 |year=2001 |pmid=11388459 |doi=10.1271/bbb.65.823 |s2cid=30118947 |doi-access=free }}</ref><ref name="pmid16716928">{{cite journal |vauthors=Saito Y, Taguchi H, Akamatsu T |title=Fate of transforming bacterial genome following incorporation into competent cells of Bacillus subtilis: a continuous length of incorporated DNA |journal=J. Biosci. Bioeng. |volume=101 |issue=3 |pages=257–62 |year=2006 |pmid=16716928 |doi=10.1263/jbb.101.257 }}</ref>  Transformation appears to be common among bacterial species, and at least 60 species are known to have the natural ability to become competent for transformation.<ref name="pmid17997281">{{cite journal |vauthors=Johnsborg O, Eldholm V, Håvarstein LS |title=Natural genetic transformation: prevalence, mechanisms and function |journal=Res. Microbiol. |volume=158 |issue=10 |pages=767–78 |year=2007 |pmid=17997281 |doi=10.1016/j.resmic.2007.09.004 |doi-access=free }}</ref>  The development of competence in nature is usually associated with stressful environmental conditions, and seems to be an adaptation for facilitating repair of DNA damage in recipient cells.<ref>Bernstein H, Bernstein C, Michod RE (2012). DNA repair as the primary adaptive function of sex in bacteria and eukaryotes.  Chapter 1: pp.1-49 in: DNA Repair: New Research, Sakura Kimura and Sora Shimizu editors. Nova Sci. Publ., Hauppauge, N.Y.  {{ISBN|978-1-62100-808-8}} https://www.novapublishers.com/catalog/product_info.php?products_id=31918 {{Webarchive|url=https://web.archive.org/web/20131029202307/https://www.novapublishers.com/catalog/product_info.php?products_id=31918 |date=2013-10-29 }}</ref>