Editing Caenorhabditis elegans (section)

=== Cell division and cell cycle ===
Research into [[meiosis]] has been considerably simplified since every germ cell nucleus is at the same given position as it moves down the gonad, so is at the same stage in meiosis. In an early phase of meiosis, the oocytes become extremely resistant to radiation and this resistance depends on expression of genes ''rad51'' and ''atm'' that have key roles in recombinational repair.<ref name="pmid11058122">{{cite journal | vauthors = Takanami T, Mori A, Takahashi H, Higashitani A | title = Hyper-resistance of meiotic cells to radiation due to a strong expression of a single recA-like gene in Caenorhabditis elegans | journal = Nucleic Acids Research | volume = 28 | issue = 21 | pages = 4232–6 | date = November 2000 | pmid = 11058122 | pmc = 113154 | doi = 10.1093/nar/28.21.4232 }}</ref><ref name="pmid14646232">{{cite journal | vauthors = Takanami T, Zhang Y, Aoki H, Abe T, Yoshida S, Takahashi H, Horiuchi S, Higashitani A | title = Efficient repair of DNA damage induced by heavy ion particles in meiotic prophase I nuclei of Caenorhabditis elegans | journal = Journal of Radiation Research | volume = 44 | issue = 3 | pages = 271–6 | date = September 2003 | pmid = 14646232 | doi = 10.1269/jrr.44.271 | bibcode = 2003JRadR..44..271T | doi-access = free }}</ref> Gene ''[[MRE11A|mre-11]]'' also plays a crucial role in recombinational repair of DNA damage during meiosis.<ref name=Chin>{{cite journal | vauthors = Chin GM, Villeneuve AM | title = C. elegans mre-11 is required for meiotic recombination and DNA repair but is dispensable for the meiotic G(2) DNA damage checkpoint | journal = Genes & Development | volume = 15 | issue = 5 | pages = 522–34 | date = March 2001 | pmid = 11238374 | pmc = 312651 | doi = 10.1101/gad.864101 }}</ref>  Furthermore, during [[meiosis]] in ''C. elegans'' the tumor suppressor [[BRCA1]]/BRC-1 and the structural maintenance of chromosomes [[SMC5]]/[[SMC6]] protein complex interact to promote high fidelity repair of [[Double-strand break repair model|DNA double-strand breaks]].<ref>{{cite journal |vauthors=Toraason E, Salagean A, Almanzar DE, Brown JE, Richter CM, Kurhanewicz NA, Rog O, Libuda DE |title=BRCA1/BRC-1 and SMC-5/6 regulate DNA repair pathway engagement during Caenorhabditis elegans meiosis |journal=eLife |volume=13 |issue= |pages= |date=August 2024 |pmid=39115289 |pmc=11368404 |doi=10.7554/eLife.80687 |doi-access=free |url=}}</ref>

A study of the frequency of outcrossing in natural populations showed that [[selfing]] is the predominant mode of reproduction in ''C. elegans'', but that infrequent outcrossing events occur at a rate around 1%.<ref name="pmid16005289">{{cite journal | vauthors = Barrière A, Félix MA | title = High local genetic diversity and low outcrossing rate in Caenorhabditis elegans natural populations | journal = Current Biology | volume = 15 | issue = 13 | pages = 1176–84 | date = July 2005 | pmid = 16005289 | doi = 10.1016/j.cub.2005.06.022 | arxiv = q-bio/0508003 | bibcode = 2005CBio...15.1176B | s2cid = 2229622 }}</ref>  Meioses that result in selfing are unlikely to contribute significantly to beneficial genetic variability, but these meioses may provide the adaptive benefit of recombinational repair of DNA damages that arise, especially under stressful conditions.<ref>Bernstein H, Bernstein C (July 2010) "Evolutionary Origin of Recombination during Meiosis," BioScience 60(7), 498-505. https://doi.org/10.1525/bio.2010.60.7.5</ref>