{"39747":{"#nid":"39747","#data":{"type":"news","title":"Biologists Find Gene Network That Gave Rise to First Tooth","body":[{"value":"\u003Cp\u003EScientists at the Georgia Institute of Technology have identified a set of genes that they believe was responsible for forming the first teeth in vertebrates. This gene network is believed to have been responsible for the formation of teeth in the throat of the first jawless fish half a billion years ago and are still responsible for the development of teeth in the jaws of all animals today. The research appears online in the journal PLoS Biology beginning February 10.\u003C\/p\u003E\u003Cp\u003E\n\n\u003C\/p\u003E\u003Cp class=\u0022MsoNormal\u0022\u003E\u0022We have identified a core set of genes that probably made\nthe first tooth in these ancient vertebrates and still governs the formation of\nteeth in modern vertebrates including humans. So it\u0027s likely that every tooth\nmade throughout the evolution of vertebrates has used this core set of genes,\u0022\nsaid Gareth Fraser, postdoctoral fellow in Georgia Tech\u0027s School of Biology.\u003C\/p\u003E\n\n\u003Cp class=\u0022MsoNormal\u0022\u003E\u0026nbsp;\u0026nbsp;The first\nvertebrates to have teeth were a group of eel-like jawless fish known as the\nconodonts that had teeth not in their mouth, but lining the throat. They\u0027re\nlong since extinct, but Fraser, along with J. Todd Streelman, assistant\nprofessor in Georgia Tech\u0027s School of Biology, investigated the teeth in a\ngroup of fish known for their rapid rate of evolution, the cichlids of Africa\u0027s\nLake Malawi. The cichlids have teeth in both their oral jaws, like humans, and\ndeep in their throats on a pharyngeal jaw. A co-author of the paper, Darrin\nHulsey, first identified a surprising positive correlation between the number\nof teeth in the oral jaw and throat in these fish.\u003C\/p\u003E\n\n\u003Cp class=\u0022MsoNormal\u0022\u003E\u0026nbsp;\u0022Originally, I\nthought there wouldn\u0027t be a correlation due to the developmental differences\nand the evolutionary distinction between the two jaw regions, but it turns out\nthere is,\u0022 explained Fraser. \u0022So fish that have fewer oral teeth also have\nfewer pharyngeal teeth. This shows that on some level there\u0027s a genetic control\nthat governs the number of teeth in both regions.\u0022\u003C\/p\u003E\n\n\u003Cp class=\u0022MsoNormal\u0022\u003E\u0026nbsp;The team\ninvestigated what this control might be by using a technique localizing gene expression\nin the cells during tooth development, known as insitu hybridization, and found\nthat a common genetic network governs teeth in both locations.\u003C\/p\u003E\n\n\u003Cp class=\u0022MsoNormal\u0022\u003E\u0026nbsp;\u0022So seemingly,\nregardless of where you grow a tooth, whether it\u0027s in the jaw or the pharynx,\nyou use the same core set of genes to do it,\u0022 said Streelman. \u0022We also think\nit\u0027s probable that this network is not just acting in teeth, but also in other\nsimilarly patterned structures like hair and feathers.\u0022\u003C\/p\u003E\n\n\u003Cp class=\u0022MsoNormal\u0022\u003EIn another finding in the same paper, Fraser and colleagues\nfound that a set of genes known as Hox genes, which control where limbs and\norgans should form during development, are expressed in the teeth and jaws\nfound in the pharynx. It has long been known that Hox genes are not expressed\nin the oral jaw, and it\u0027s widely believed that this lack of expression is\nresponsible for the evolution of the oral jaws. Fraser hypothesized that these\nHox genes should be \u0022switched off\u0022 during the formation of the pharyngeal jaw\nas is the case for the oral jaw. The study shows that this isn\u0027t the case. \u003C\/p\u003E\n\n\u003Cp class=\u0022MsoNormal\u0022\u003E\u0026nbsp;\u0022The prevailing theory suggests that the loss of Hox genes\nin the oral region during the transition from jawless to jawed vertebrates\nfacilitated the evolution and diversity of oral jaws. Our data suggest that\nloss of Hox genes is not an absolute requirement to make a toothed, functional\njaw,\u0022 said Streelman.\u003C\/p\u003E\n\n\u003Cp class=\u0022MsoNormal\u0022\u003EThe authors of the study were Gareth J. Fraser, C. Darrin\nHulsey, Ryan F. Bloomquist, Kristine Uyesugi, Nancy R. Manley and J. Todd\nStreelman.\u003C\/p\u003E\n\n\n\n\n\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"Scientists at the Georgia Institute of Technology have identified a set of genes that they believe was responsible for forming the first teeth in vertebrates.","format":"limited_html"}],"field_summary_sentence":[{"value":"Scientists find correlation between oral teeth and teeth in the"}],"uid":"27310","created_gmt":"2009-01-27 01:00:00","changed_gmt":"2016-10-08 03:01:20","author":"David Terraso","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2009-02-10T00:00:00-05:00","iso_date":"2009-02-10T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"39748":{"id":"39748","type":"image","title":"tjk14785.jpg","body":null,"created":"1449174117","gmt_created":"2015-12-03 20:21:57","changed":"1475894256","gmt_changed":"2016-10-08 02:37:36","alt":"","file":{"fid":"189638","name":"tjk14785.jpg","image_path":"\/sites\/default\/files\/images\/tjk14785_1.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tjk14785_1.jpg","mime":"image\/jpeg","size":203699,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tjk14785_1.jpg?itok=nRKdMG8c"}}},"media_ids":["39748"],"related_links":[{"url":"http:\/\/www.biology.gatech.edu\/faculty\/todd-streelman\/","title":"Todd Streelman"},{"url":"http:\/\/www.biology.gatech.edu\/faculty\/todd-streelman\/gfraser.php","title":"Gareth Fraser"}],"groups":[{"id":"1183","name":"Home"}],"categories":[{"id":"146","name":"Life Sciences and Biology"},{"id":"135","name":"Research"}],"keywords":[{"id":"1473","name":"cichlids"},{"id":"1475","name":"fraser"},{"id":"169284","name":"streelman"},{"id":"1471","name":"teeth"},{"id":"1472","name":"tooth"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003E\u003Cstrong\u003EGeorgia Tech Media Relations\u003C\/strong\u003E\u003Cbr \/\u003ELaura Diamond\u003Cbr \/\u003E\u003Ca href=\u0022mailto:laura.diamond@comm.gatech.edu\u0022\u003Elaura.diamond@comm.gatech.edu\u003C\/a\u003E\u003Cbr \/\u003E404-894-6016\u003Cbr \/\u003EJason Maderer\u003Cbr \/\u003E\u003Ca href=\u0022mailto:maderer@gatech.edu\u0022\u003Emaderer@gatech.edu\u003C\/a\u003E\u003Cbr \/\u003E404-660-2926\u003C\/p\u003E","format":"limited_html"}],"email":["david.terraso@comm.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}