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. Author manuscript; available in PMC: 2014 Oct 3.
Published in final edited form as: Nat Commun. 2014 Apr 3;5:3509. doi: 10.1038/ncomms4509

Figure 2. Mutation of 220-bp repeats and the linker region.

Figure 2

424 mutations (99 mutated strands) were found in 150 sequenced spores.

a, Spores were classified by the number of mutations over the total sequenced region. The number of spores (histogram) and the number of mutations (pie chart) per each class are shown. If the distribution of mutation counts followed a Poisson model (expected under the null assumption of independence of individual mutation events), the variance-to-mean ratio (VMR, distributed as the reduced chi-square under the Poisson model), would be equal to 1. VMR was found to be 30.98, significantly larger than 1 (P < 1*10-6), indicating strong over-dispersion of mutation counts.

b, Mutation profile summarizes C/T and G/A mutations in 150 sequenced spores including the 24 spores analyzed earlier (Fig. 1). To determine if ample mutation of the linker region was associated with accidental bursts of RIP activity, every mutation was assigned two attributes: [1] its location in the construct, being either in the repeat unit, or the linker, or the flanking region, and [2] the total number of mutations found together on the same stand. The data did not reveal any relationship between the number of mutations on a given strand and their partitioning into single-copy or repetitive regions (P = 0.11, Fisher's Exact Test), suggesting that accidental bursts of RIP activity did not preferentially affect the linker region.