--- _id: '2412' abstract: - lang: eng text: 'Background: The CRISPR/Cas system is known to act as an adaptive and heritable immune system in Eubacteria and Archaea. Immunity is encoded in an array of spacer sequences. Each spacer can provide specific immunity to invasive elements that carry the same or a similar sequence. Even in closely related strains, spacer content is very dynamic and evolves quickly. Standard models of nucleotide evolutioncannot be applied to quantify its rate of change since processes other than single nucleotide changes determine its evolution.Methods We present probabilistic models that are specific for spacer content evolution. They account for the different processes of insertion and deletion. Insertions can be constrained to occur on one end only or are allowed to occur throughout the array. One deletion event can affect one spacer or a whole fragment of adjacent spacers. Parameters of the underlying models are estimated for a pair of arrays by maximum likelihood using explicit ancestor enumeration.Results Simulations show that parameters are well estimated on average under the models presented here. There is a bias in the rate estimation when including fragment deletions. The models also estimate times between pairs of strains. But with increasing time, spacer overlap goes to zero, and thus there is an upper bound on the distance that can be estimated. Spacer content similarities are displayed in a distance based phylogeny using the estimated times.We use the presented models to analyze different Yersinia pestis data sets and find that the results among them are largely congruent. The models also capture the variation in diversity of spacers among the data sets. A comparison of spacer-based phylogenies and Cas gene phylogenies shows that they resolve very different time scales for this data set.Conclusions The simulations and data analyses show that the presented models are useful for quantifying spacer content evolution and for displaying spacer content similarities of closely related strains in a phylogeny. This allows for comparisons of different CRISPR arrays or for comparisons between CRISPR arrays and nucleotide substitution rates.' author: - first_name: Anne full_name: Kupczok, Anne id: 2BB22BC2-F248-11E8-B48F-1D18A9856A87 last_name: Kupczok - first_name: Jonathan P full_name: Bollback, Jonathan P id: 2C6FA9CC-F248-11E8-B48F-1D18A9856A87 last_name: Bollback orcid: 0000-0002-4624-4612 citation: ama: Kupczok A, Bollback JP. Probabilistic models for CRISPR spacer content evolution . BMC Evolutionary Biology. 2013;13(1):54-54. doi:10.1186/1471-2148-13-54 apa: Kupczok, A., & Bollback, J. P. (2013). Probabilistic models for CRISPR spacer content evolution . BMC Evolutionary Biology. BioMed Central. https://doi.org/10.1186/1471-2148-13-54 chicago: Kupczok, Anne, and Jonathan P Bollback. “Probabilistic Models for CRISPR Spacer Content Evolution .” BMC Evolutionary Biology. BioMed Central, 2013. https://doi.org/10.1186/1471-2148-13-54. ieee: A. Kupczok and J. P. Bollback, “Probabilistic models for CRISPR spacer content evolution ,” BMC Evolutionary Biology, vol. 13, no. 1. BioMed Central, pp. 54–54, 2013. ista: Kupczok A, Bollback JP. 2013. Probabilistic models for CRISPR spacer content evolution . BMC Evolutionary Biology. 13(1), 54–54. mla: Kupczok, Anne, and Jonathan P. Bollback. “Probabilistic Models for CRISPR Spacer Content Evolution .” BMC Evolutionary Biology, vol. 13, no. 1, BioMed Central, 2013, pp. 54–54, doi:10.1186/1471-2148-13-54. short: A. Kupczok, J.P. Bollback, BMC Evolutionary Biology 13 (2013) 54–54. date_created: 2018-12-11T11:57:31Z date_published: 2013-02-26T00:00:00Z date_updated: 2021-01-12T06:57:20Z day: '26' ddc: - '576' department: - _id: JoBo doi: 10.1186/1471-2148-13-54 file: - access_level: open_access checksum: 029c7e0b198c19312b66ecce3cabb22f content_type: application/pdf creator: system date_created: 2018-12-12T10:17:15Z date_updated: 2020-07-14T12:45:40Z file_id: '5268' file_name: IST-2015-397-v1+1_1471-2148-13-54.pdf file_size: 518729 relation: main_file file_date_updated: 2020-07-14T12:45:40Z has_accepted_license: '1' intvolume: ' 13' issue: '1' language: - iso: eng month: '02' oa: 1 oa_version: Published Version page: 54 - 54 publication: BMC Evolutionary Biology publication_status: published publisher: BioMed Central publist_id: '4514' pubrep_id: '397' quality_controlled: '1' scopus_import: 1 status: public title: 'Probabilistic models for CRISPR spacer content evolution ' tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 13 year: '2013' ...