{"id":237791,"date":"2017-05-16T14:35:25","date_gmt":"2017-05-16T17:35:25","guid":{"rendered":"http:\/\/revistapesquisa.fapesp.br\/?p=237791\/"},"modified":"2017-05-16T14:35:25","modified_gmt":"2017-05-16T17:35:25","slug":"why-snakes-dont-have-legs","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/why-snakes-dont-have-legs\/","title":{"rendered":"Why snakes don\u2019t have legs"},"content":{"rendered":"<div id=\"attachment_237792\" style=\"max-width: 310px\" class=\"wp-caption alignright\"><a href=\"http:\/\/revistapesquisa.fapesp.br\/wp-content\/uploads\/2017\/05\/012_tecno_red_tailed_249.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-237792\" src=\"http:\/\/revistapesquisa.fapesp.br\/wp-content\/uploads\/2017\/05\/012_tecno_red_tailed_249-300x199.jpg\" alt=\"\" width=\"300\" height=\"199\" \/><p class=\"wp-caption-text\"><span class=\"media-credits-inline\">Gnangarra\/Wikicommons <\/span><\/a> Python: missing sequence of 17 base-pairs meant snakes grew no legs<span class=\"media-credits\">Gnangarra\/Wikicommons <\/span><\/p><\/div>\n<p>TTCTGAGGTAACTTCCT. This sequence of 17 base-pairs \u2013 the chemical units that make up DNA \u2013 was missing along a stretch of snake genome, causing the reptiles to gradually lose their limbs (<em>Cell<\/em>, October 20, 2016). So concluded a study coordinated by researchers at the Lawrence Berkeley National Laboratory in Berkeley, California, with the participation of Brazilian molecular biologist Uir\u00e1 Souto Melo. The sequence is from a regulatory region that governs the functioning of the sonic hedgehog gene (<em>Shh<\/em>), which produces a protein important to limb development. Called ZRS enhancer, this stretch of DNA is well conserved across the vertebrate genome but displays some deletions in snake DNA. In the case of modern, legless snakes, this 17 base-pair sequence is missing. Using the gene-editing tool CRISPR-Cas9 \u2013 a molecular biology technique that enables editing of targeted stretches of gene \u2013 researchers inserted and deleted the enhancer in transgenic mice. When they replaced the mouse enhancer with a version from legged vertebrates, like humans, horses, and chickens, the mice developed limbs. However, when they inserted the enhancer from one of the two snake species under study, the mice did not grow limbs. \u201cWe saw that the sequence is enough to control leg formation,\u201d explains Melo, who completed part of his doctorate in 2016 at the Lawrence Berkeley National Laboratory and currently works at the Human Genome and Stem-Cell Research Center (HUG-CELL), of the University of S\u00e3o Paulo (USP).<\/p>\n","protected":false},"excerpt":{"rendered":"Missing sequence of 17 base-pairs meant snakes grew no legs","protected":false},"author":475,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[168],"tags":[209,231,237],"coauthors":[785],"class_list":["post-237791","post","type-post","status-publish","format-standard","hentry","category-technoscience","tag-biology","tag-evolution","tag-genetics"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/237791","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/475"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=237791"}],"version-history":[{"count":0,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/237791\/revisions"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=237791"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=237791"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=237791"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=237791"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}