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BioMed Research International
Volume 2016, Article ID 7237053, 7 pages
Research Article

A Comprehensive Curation Shows the Dynamic Evolutionary Patterns of Prokaryotic CRISPRs

1Shenzhen Institutes of Advanced Technology and Key Lab for Health Informatics, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China
2Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China
3College of Computer Science and Technology, Jilin University, Changchun, Jilin 130012, China
4Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education, Jilin University, Changchun, Jilin 130012, China

Received 24 January 2016; Revised 24 March 2016; Accepted 28 March 2016

Academic Editor: Hongwei Wang

Copyright © 2016 Guoqin Mai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Motivation. Clustered regularly interspaced short palindromic repeat (CRISPR) is a genetic element with active regulation roles for foreign invasive genes in the prokaryotic genomes and has been engineered to work with the CRISPR-associated sequence (Cas) gene Cas9 as one of the modern genome editing technologies. Due to inconsistent definitions, the existing CRISPR detection programs seem to have missed some weak CRISPR signals. Results. This study manually curates all the currently annotated CRISPR elements in the prokaryotic genomes and proposes 95 updates to the annotations. A new definition is proposed to cover all the CRISPRs. The comprehensive comparison of CRISPR numbers on the taxonomic levels of both domains and genus shows high variations for closely related species even in the same genus. The detailed investigation of how CRISPRs are evolutionarily manipulated in the 8 completely sequenced species in the genus Thermoanaerobacter demonstrates that transposons act as a frequent tool for splitting long CRISPRs into shorter ones along a long evolutionary history.