external page Nature Communications<\/a>, the researchers from ETH have demonstrated that unique satellite DNA patterns on each pair of chromosomes, comparable to a barcode on a product in a supermarket, help matching chromosomes find each other.\u00a0<\/p>\nJunk DNA becomes a matchmaker <\/p>\n
The ETH researchers led by Prof. Jagannathan argue that it is not enough to simply remove satellite DNA from just one chromosome. With only one \u2018barcode\u2019 disrupted, all of the other chromosome pairs with intact satellite DNA \u2018barcodes\u2019 can find each other. Ultimately, only the pair of chromosomes from which the researchers removed the barcode remains. They find each other like the last two face-down cards in a game of Memory.\u00a0<\/p>\n
Therefore, the ETH researchers removed the satellite DNA barcode from two different chromosomes, leaving the two pairs without any guidance.<\/p>\n
And indeed: without their barcode, the partner selection went awry and failed, meaning that the chromosomes frequently docked with the wrong partners. \u201cThis showed us that satellite DNA functions as a recognition aid and ensures that the chromosomes that belong together can reliably find one another,\u201d says Lena Skrutl, the study\u2019s lead author.\u00a0<\/p>\n
A glue-like protein binds matching chromosomes <\/p>\n
Simply recognising each other, however, is not enough. The researchers went on to discover that chromosome pairing also requires a molecular \u2018glue\u2019 to properly \u2018marry\u2019 the two partners together. A protein called D1 plays this role. It recognises the matching barcodes on the chromosomes that belong together, binds them and adheres to the two together.\u00a0\u00a0<\/p>\n
However, if the recognition pattern on one of the two chromosomes is altered \u2013 for example, if part of the barcode is deleted or changes occur due to natural mutations \u2013 the D1 protein can bond two chromosomes together that do not belong together. The pairing then goes wrong.<\/p>\n
\u201cOur research answers the question of how chromosome pairs recognise each other in the fruit fly Drosophila, so that meiosis proceeds correctly,\u201d ETH Professor Jagannathan states. Whether this mechanism is universal and, for example, also plays a role in humans has not yet been investigated.\u00a0<\/p>\n
\u201cWhile we have carried out pure basic research on the model organism Drosophila, we believe it is possible that this pairing mechanism also occurs in other species.\u201d One thing, however, has already become clear to Jagannathan: \u201cThe term \u2018junk DNA\u2019 is no longer tenable. We clearly demonstrate that this so-called rubbish has an important function during meiosis in the fruit fly,\u201d he emphasises.<\/p>\n
Possible role in speciation\u00a0 <\/p>\n
The new findings also explain how new species arise. Satellite DNA changes a great deal more rapidly than the rest of the genome. As long as individuals of a species produce offspring with one another, the satellite DNA barcodes remain similar across the population due to the constant mixing of genetic material.\u00a0<\/p>\n
Individuals with recognition patterns that differ too greatly suffer from meiosis defects and are unable to reproduce.\u00a0\u00a0<\/p>\n
However, if a population of an animal species becomes geographically isolated \u2013 for example, due to the formation of a mountain range over millions of years \u2013 the satellite DNA in both groups evolves independently of one another. When the two groups meet again after a long period of time, the recognition patterns of the chromosomes no longer match. The result: the animals can no longer reproduce, and one species has become two.<\/p>\n
\u2018Studies on crosses between Drosophila melanogaster and its relative Drosophila simulans are consistent with this idea,\u2019 says Jagannathan. The two species diverged two to three million years ago. The barcodes of their chromosomes now differ so greatly that massive chromosome pairing defects occur during meiosis in hybrids.<\/p>\n","protected":false},"excerpt":{"rendered":"The body cells of humans and animals contain a double set of chromosomes. One half of the genetic…\n","protected":false},"author":2,"featured_media":120215,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[6],"tags":[336,12476,3414,1202,51],"class_list":["post-120214","post","type-post","status-publish","format-standard","has-post-thumbnail","category-zurich","tag-biotechnology","tag-d-biol","tag-evolution","tag-news","tag-zurich"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ch\/117155742598188040","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts\/120214","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/comments?post=120214"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts\/120214\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/media\/120215"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/media?parent=120214"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/categories?post=120214"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/tags?post=120214"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}