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The gene for the leucine transfer RNA with a UAA anticodon [tRNA\n            <jats:sup>Leu<\/jats:sup>\n            (UAA)] from five diverse cyanobacteria and several major groups of chloroplasts contains a single group I intron. The intron is conserved in secondary structure and primary sequence, and occupies the same position, within the UAA anticodon. The homology of the intron across chloroplasts and cyanobacteria implies that it was present in their common ancestor and that it has been maintained in their genomes for at least 1 billion years.\n          <\/jats:p>","DOI":"10.1126\/science.2125748","type":"journal-article","created":{"date-parts":[[2006,10,5]],"date-time":"2006-10-05T22:10:14Z","timestamp":1160086214000},"page":"1570-1573","source":"Crossref","is-referenced-by-count":180,"title":["An Ancient Group I Intron Shared by Eubacteria and Chloroplasts"],"prefix":"10.1126","volume":"250","author":[{"given":"Maria G.","family":"Kuhsel","sequence":"first","affiliation":[{"name":"Department of Biology, Indiana University, Bloomington, IN 47405."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Roderick","family":"Strickland","sequence":"additional","affiliation":[{"name":"Department of Biology, Indiana University, Bloomington, IN 47405."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jeffrey D.","family":"Palmer","sequence":"additional","affiliation":[{"name":"Department of Biology, Indiana University, Bloomington, IN 47405."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"221","reference":[{"key":"e_1_2_1_1_1","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/0168-9525(89)90083-8","volume":"5","year":"1989","unstructured":"BELFORT, M, BACTERIOPHAGE INTRONS - PARASITES WITHIN PARASITES, TRENDS IN GENETICS 5: 209 (1989).","journal-title":"TRENDS IN GENETICS"},{"key":"e_1_2_1_2_1","first-page":"283","volume":"315","year":"1985","unstructured":"CAVALIERSMITH, T, SELFISH DNA AND THE ORIGIN OF INTRONS, NATURE 315: 283 (1985).","journal-title":"NATURE"},{"key":"e_1_2_1_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/0092-8674(86)90751-8"},{"key":"e_1_2_1_4_1","doi-asserted-by":"crossref","first-page":"259","DOI":"10.1016\/0378-1119(88)90492-1","volume":"73","year":"1988","unstructured":"CECH, T.R., CONSERVED SEQUENCES AND STRUCTURES OF GROUP-I INTRONS - BUILDING AN ACTIVE-SITE FOR RNA CATALYSIS - A REVIEW, GENE 73: 259 (1988).","journal-title":"GENE"},{"key":"e_1_2_1_5_1","first-page":"1271","volume":"83","year":"1986","unstructured":"DARNELL, J.E., SPECULATIONS ON THE EARLY COURSE OF EVOLUTION, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 83: 1271 (1986).","journal-title":"PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA"},{"key":"e_1_2_1_6_1","doi-asserted-by":"crossref","first-page":"2015","DOI":"10.1002\/j.1460-2075.1989.tb03609.x","volume":"8","year":"1989","unstructured":"DIBB, N.J., EVIDENCE THAT INTRONS AROSE AT PROTO-SPLICE SITES, EMBO JOURNAL 8: 2015 (1989).","journal-title":"EMBO JOURNAL"},{"key":"e_1_2_1_7_1","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1016\/0378-1119(89)90034-6","volume":"82","year":"1989","unstructured":"DUJON, B, GROUP-I INTRONS AS MOBILE GENETIC ELEMENTS - FACTS AND MECHANISTIC SPECULATIONS - A REVIEW, GENE 82: 91 (1989).","journal-title":"GENE"},{"key":"e_1_2_1_8_1","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1016\/0378-1119(88)90083-2","volume":"71","year":"1988","unstructured":"EVRARD, J.L., A CLASS-I INTRON IN A CYANELLE TRANSFER-RNA GENE FROM CYANOPHORA-PARADOXA - PHYLOGENETIC RELATIONSHIP BETWEEN CYANELLES AND PLANT CHLOROPLASTS, GENE 71: 115 (1988).","journal-title":"GENE"},{"key":"e_1_2_1_9_1","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1016\/0092-8674(86)90730-0","volume":"46","year":"1986","unstructured":"GILBERT, W, ON THE ANTIQUITY OF INTRONS, CELL 46: 151 (1986).","journal-title":"CELL"},{"key":"e_1_2_1_10_1","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1038\/271501a0","volume":"271","year":"1978","unstructured":"GILBERT, W, WHY GENES IN PIECES, NATURE 271: 501 (1978).","journal-title":"NATURE"},{"key":"e_1_2_1_11_1","doi-asserted-by":"crossref","first-page":"16156","DOI":"10.1016\/S0021-9258(17)36214-2","volume":"260","year":"1985","unstructured":"GINGRICH, J.C., THE EUGLENA-GRACILIS CHLOROPLAST RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE GENE .1. 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