Editing DNA (section)

=== Extracellular nucleic acids ===
Naked extracellular DNA (eDNA), most of it released by cell death, is nearly ubiquitous in the environment. Its concentration in soil may be as high as 2 μg/L, and its concentration in natural aquatic environments may be as high at 88 μg/L.<ref name=Tani_2010>{{cite book | vauthors = Tani K, Nasu M | veditors = Kikuchi Y, Rykova EY | title = Extracellular Nucleic Acids |url=https://archive.org/details/extracellularnuc00kiku |url-access=limited |publisher=Springer |date=2010 |pages=[https://archive.org/details/extracellularnuc00kiku/page/n35 25]–38 |chapter=Roles of Extracellular DNA in Bacterial Ecosystems |isbn=978-3-642-12616-1}}</ref> Various possible functions have been proposed for eDNA: it may be involved in [[horizontal gene transfer]];<ref name="Vlassov_2007">{{cite journal | vauthors = Vlassov VV, Laktionov PP, Rykova EY | title = Extracellular nucleic acids | journal = BioEssays | volume = 29 | issue = 7 | pages = 654–67 | date = July 2007 | pmid = 17563084 | doi = 10.1002/bies.20604 | s2cid = 32463239 }}</ref> it may provide nutrients;<ref name="pmid11591672">{{cite journal | vauthors = Finkel SE, Kolter R | title = DNA as a nutrient: novel role for bacterial competence gene homologs | journal = Journal of Bacteriology | volume = 183 | issue = 21 | pages = 6288–93 | date = November 2001 | pmid = 11591672 | pmc = 100116 | doi = 10.1128/JB.183.21.6288-6293.2001 }}</ref> and it may act as a buffer to recruit or titrate ions or antibiotics.<ref name=Mulcahy_2008>{{cite journal | vauthors = Mulcahy H, Charron-Mazenod L, Lewenza S | title = Extracellular DNA chelates cations and induces antibiotic resistance in Pseudomonas aeruginosa biofilms | journal = PLOS Pathogens | volume = 4 | issue = 11 | pages = e1000213 | date = November 2008 | pmid = 19023416 | pmc = 2581603 | doi = 10.1371/journal.ppat.1000213 | doi-access = free }}</ref> Extracellular DNA acts as a functional extracellular matrix component in the [[biofilm]]s of several bacterial species. It may act as a recognition factor to regulate the attachment and dispersal of specific cell types in the biofilm;<ref name=Berne_2010>{{cite journal | vauthors = Berne C, Kysela DT, Brun YV | title = A bacterial extracellular DNA inhibits settling of motile progeny cells within a biofilm | journal = Molecular Microbiology | volume = 77 | issue = 4 | pages = 815–29 | date = August 2010 | pmid = 20598083 | pmc = 2962764 | doi = 10.1111/j.1365-2958.2010.07267.x }}</ref> it may contribute to biofilm formation;<ref name=Whitchurch_2002>{{cite journal | vauthors = Whitchurch CB, Tolker-Nielsen T, Ragas PC, Mattick JS | title = Extracellular DNA required for bacterial biofilm formation | journal = Science | volume = 295 | issue = 5559 | pages = 1487 | date = February 2002 | pmid = 11859186 | doi = 10.1126/science.295.5559.1487 }}</ref> and it may contribute to the biofilm's physical strength and resistance to biological stress.<ref name=Hu_2012>{{cite journal | vauthors = Hu W, Li L, Sharma S, Wang J, McHardy I, Lux R, Yang Z, He X, Gimzewski JK, Li Y, Shi W | title = DNA builds and strengthens the extracellular matrix in Myxococcus xanthus biofilms by interacting with exopolysaccharides | journal = PLOS ONE | volume = 7 | issue = 12 | pages = e51905 | year = 2012 | pmid = 23300576 | pmc = 3530553 | doi = 10.1371/journal.pone.0051905 | bibcode = 2012PLoSO...751905H | doi-access = free }}</ref>

[[Cell-free fetal DNA]] is found in the blood of the mother, and can be sequenced to determine a great deal of information about the developing fetus.<ref name="Hui_2013">{{cite journal | vauthors = Hui L, Bianchi DW | title = Recent advances in the prenatal interrogation of the human fetal genome | journal = Trends in Genetics | volume = 29 | issue = 2 | pages = 84–91 | date = February 2013 | pmid = 23158400 | pmc = 4378900 | doi = 10.1016/j.tig.2012.10.013 }}</ref>

Under the name of [[environmental DNA]] eDNA has seen increased use in the natural sciences as a survey tool for [[ecology]], monitoring the movements and presence of species in water, air, or on land, and assessing an area's biodiversity.<ref>{{cite journal | vauthors = Foote AD, Thomsen PF, Sveegaard S, Wahlberg M, Kielgast J, Kyhn LA, Salling AB, Galatius A, Orlando L, Gilbert MT | display-authors = 6 | title = Investigating the potential use of environmental DNA (eDNA) for genetic monitoring of marine mammals | journal = PLOS ONE | volume = 7 | issue = 8 | pages = e41781 | year = 2012 | pmid = 22952587 | pmc = 3430683 | doi = 10.1371/journal.pone.0041781 | bibcode = 2012PLoSO...741781F | doi-access = free }}</ref><ref>{{Cite web | url=https://www.the-scientist.com/news-opinion/researchers-detect-land-animals-using-dna-in-nearby-water-bodies-67481 | title=Researchers Detect Land Animals Using DNA in Nearby Water Bodies}}</ref>