Editing Endosymbiont (section)

{{short description|Organism that lives within the body or cells of another organism}}
{{Use dmy dates|date=January 2020}}
[[File:Endosymbiosis.PNG|thumb|200px|A representation of the [[endosymbiotic theory]]]]

An '''endosymbiont''' or '''endobiont'''<ref name="KingDom">{{cite book |vauthors=Margulis L, Chapman MJ |author1-link=Lynn Margulis  |title=Kingdoms & domains an illustrated guide to the phyla of life on Earth |date=2009 |publisher=Academic Press/Elsevier |location=Amsterdam |isbn=978-0-08-092014-6 |page=493 |edition=4th |url=https://books.google.com/books?id=9IWaqAOGyt4C&pg=PA493}}</ref> is an [[organism]] that lives within the body or cells of another organism. Typically the two organisms are in a [[mutualism (biology)|mutualistic]] relationship. Examples are [[nitrogen-fixing]] [[bacteria]] (called [[rhizobia]]), which live in the [[root nodule]]s of [[legume]]s, single-cell [[algae]] inside [[Coral reef|reef-building]] [[coral]]s, and bacterial endosymbionts that provide essential nutrients to [[insect]]s.<ref name="pmid29393944">{{cite journal |vauthors=Mergaert P |date=April 2018 |title=Role of antimicrobial peptides in controlling symbiotic bacterial populations |journal=Natural Product Reports |volume=35 |issue=4 |pages=336–356 |doi=10.1039/c7np00056a |pmid=29393944}}</ref><ref name="pmid15178799">{{cite journal |vauthors=Little AF, van Oppen MJ, Willis BL |date=June 2004 |title=Flexibility in algal endosymbioses shapes growth in reef corals |journal=Science |volume=304 |issue=5676 |pages=1492–1494 |bibcode=2004Sci...304.1491L |doi=10.1126/science.1095733 |pmid=15178799 |s2cid=10050417}}</ref>

Endosymbiosis played key roles in the development of [[eukaryotes]] and plants. Roughly 2.2 billion years ago an [[archaeon]] absorbed a [[bacterium]] through [[phagocytosis]], that eventually became the [[mitochondria]] that provide energy to almost all living [[Eukaryote|eukaryotic]] cells. Approximately 1 billion years ago, some of those cells absorbed [[cyanobacteria]] that eventually became [[chloroplasts]], [[organelles]] that produce energy from sunlight.<ref>{{Cite web |last=Baisas |first=Laura |date=2024-04-18 |title=For the first time in one billion years, two lifeforms truly merged into one organism |url=https://www.popsci.com/science/two-lifeforms-merged-into-one/ |access-date=2024-04-26 |website=Popular Science |language=en-US}}</ref> Approximately 100 million years ago, a lineage of amoeba in the genus ''[[Paulinella]]'' independently engulfed a cyanobacterium that evolved to be functionally synonymous with traditional chloroplasts, called chromatophores.<ref>{{Cite journal |last1=Macorano |first1=Luis |last2=Nowack |first2=Eva C.M. |date=2021-09-13 |title=Paulinella chromatophora |url=https://linkinghub.elsevier.com/retrieve/pii/S0960982221009830 |journal=Current Biology |volume=31 |issue=17 |pages=R1024–R1026 |doi=10.1016/j.cub.2021.07.028 |bibcode=2021CBio...31R1024M |issn=0960-9822|url-access=subscription }}</ref>

Some 100 million years ago, [[UCYN-A]], a nitrogen-fixing bacterium, became an endosymbiont of the marine alga ''[[Braarudosphaera bigelowii]]'', eventually evolving into a [[nitroplast]], which fixes nitrogen.<ref name="nature.com">{{Cite journal |last=Wong |first=Carissa |date=11 April 2024 |title=Scientists discover first algae that can fix nitrogen — thanks to a tiny cell structure |journal=Nature |volume=628 |issue=8009 |page=702 |url=https://www.nature.com/articles/d41586-024-01046-z |archive-url=http://web.archive.org/web/20240414144507/https://www.nature.com/articles/d41586-024-01046-z |archive-date=14 April 2024 |access-date=16 April 2024 |publisher=Nature.com|doi=10.1038/d41586-024-01046-z |pmid=38605201 |bibcode=2024Natur.628..702W |url-access=subscription }}</ref> Similarly, [[diatom]]s in the family ''Rhopalodiaceae'' have cyanobacterial endosymbionts, called spheroid bodies or diazoplasts, which have been proposed to be in the early stages of organelle evolution.<ref>{{cite journal |title=Genomic divergence within non-photosynthetic cyanobacterial endosymbionts in rhopalodiacean diatoms |date=2017 |pmc=5638926 |pmid=29026213 |last1=Nakayama |first1=T. |last2=Inagaki |first2=Y. |journal=Scientific Reports |volume=7 |issue=1 |page=13075 |doi=10.1038/s41598-017-13578-8 |bibcode=2017NatSR...713075N }}</ref><ref>{{Cite journal |last1=Schvarcz |first1=Christopher R. |last2=Wilson |first2=Samuel T. |last3=Caffin |first3=Mathieu |last4=Stancheva |first4=Rosalina |last5=Li |first5=Qian |last6=Turk-Kubo |first6=Kendra A. |last7=White |first7=Angelicque E. |last8=Karl |first8=David M. |last9=Zehr |first9=Jonathan P. |last10=Steward |first10=Grieg F. |date=2022-02-10 |title=Overlooked and widespread pennate diatom-diazotroph symbioses in the sea |journal=Nature Communications |language=en |volume=13 |issue=1 |pages=799 |doi=10.1038/s41467-022-28065-6 |issn=2041-1723 |pmc=8831587 |pmid=35145076|bibcode=2022NatCo..13..799S }}</ref>

Symbionts are either obligate (require their host to survive) or facultative (can survive independently).<ref name="Bright-2010">{{Cite journal |last1=Bright |first1=Monika |last2=Bulgheresi |first2=Silvia |date=March 2010 |title=A complex journey: transmission of microbial symbionts |journal=Nature Reviews Microbiology |language=en |volume=8 |issue=3 |pages=218–230 |doi=10.1038/nrmicro2262 |issn=1740-1534 |pmc=2967712 |pmid=20157340}}</ref> The most common examples of obligate endosymbiosis are [[mitochondria]] and [[chloroplast]]s; however, they do not reproduce via [[mitosis]] in tandem with their host cells. Instead, they replicate via [[Fission (biology)|binary fission]], a replication process uncoupled from the host cells in which they reside.<ref>{{Cite web |title=Mitochondria, Cell Energy, ATP Synthase {{!}} Learn Science at Scitable |url=https://www.nature.com/scitable/topicpage/mitochondria-14053590/ |access-date=2024-12-31 |website=www.nature.com |language=en}}</ref><ref>{{Cite web |last=Rose |first=Ray J |date=September 20, 2019 |title=Sustaining Life: Maintaining Chloroplasts and Mitochondria and their Genomes in Plants |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC6747931/ |access-date=December 31, 2024 |website=National Library of Medicine: National Center for Biotechnology Information |publisher=Yale Journal of Biology and Medicine |pmid=31543711}}</ref> Some human parasites, e.g. ''[[Wuchereria bancrofti]]'' and ''[[Mansonella perstans]]'', thrive in their intermediate insect hosts because of an obligate endosymbiosis with ''[[Wolbachia]]'' spp.<ref name="Slatko-2010">{{Cite journal |last1=Slatko |first1=Barton E. |last2=Taylor |first2=Mark J. |last3=Foster |first3=Jeremy M. |date=2010-07-01 |title=The Wolbachia endosymbiont as an anti-filarial nematode target |url=https://doi.org/10.1007/s13199-010-0067-1 |journal=Symbiosis |language=en |volume=51 |issue=1 |pages=55–65 |bibcode=2010Symbi..51...55S |doi=10.1007/s13199-010-0067-1 |issn=1878-7665 |pmc=2918796 |pmid=20730111}}</ref> They can both be eliminated by treatments that target their bacterial host.<ref>{{Cite book |url=https://books.google.com/books?id=hEjqD-ygu8AC&dq=Wuchereria+bancrofti+obligated+endosymbiosis+Wolbachia&pg=PA786 |title=Oxford Textbook of Medicine: Infection |vauthors=Warrell D, Cox TM, Firth J, Török E |date=2012-10-11 |publisher=OUP Oxford |isbn=978-0-19-965213-6 |language=en}}</ref>

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