The Contribution of Genetic Recombination to CRISPR Array Evolution.
Bottom Line: CRISPR (clustered regularly interspaced short palindromic repeats) is a microbial immune system against foreign DNA.We analyze CRISPR data sets from four bacterial species: two Gammaproteobacteria species harboring CRISPR type I and two Streptococcus species harboring CRISPR type II loci.Genetic recombination has been proposed to accelerate adaptation by combining beneficial mutations that arose in independent lineages.
Affiliation: Institute of General Microbiology, Christian-Albrechts-University Kiel, Germany firstname.lastname@example.org.Show MeSH
Related in: MedlinePlus
Mentions: The observed stable ratios can be the result of either a constant rate of deletions and recombination events or a constant rate of deletions and the ensuing proximal deletions. To distinguish between these two alternatives, we performed additional perturbations of the original data sets. Simulated deletions are introduced into the data sets where the number of successive spacers being deleted is randomly chosen from the observed distribution of deletion length in the respective data set (supplementary table S1, Supplementary Material online). We define artificial deletions as the deletions that are inferred in the data sets following the perturbation. This analysis reveals that increasing the number of simulated deletions in the data set results in an increased number of artificial deletions (fig. 6). However, only a minority of the simulated deletions is detectable, with a ratio of artificial to simulated deletions ranging from 0.12 (S. agalactiae) to 0.3 (S. thermophilus) (fig. 6 and table 3; supplementary fig. S3, Supplementary Material online).Fig. 6.—
Affiliation: Institute of General Microbiology, Christian-Albrechts-University Kiel, Germany email@example.com.