A factor in a wild isolated Neurospora crassa strain enables a chromosome segment duplication to suppress repeat-induced point mutation.
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Date
2011-12
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Abstract
Repeat-induced point mutation (RIP) is a sexual stage-specific mutational process of Neurospora crassa and other
fungi that alters duplicated DNA sequences. Previous studies from our laboratory showed that chromosome segment
duplications (Dps) longer than ~300 kbp can dominantly suppress RIP, presumably by titration of the RIP
machinery, and that although Dps <200 kbp did not individually suppress RIP, they could do so in homozygous and
multiply heterozygous crosses, provided the sum of the duplicated DNA exceeds ~300 kbp. Here we demonstrate
suppression of RIP in a subset of progeny carrying the normally sub-threshold 154 kbp Dp(R2394) from a cross of
T(R2394) to the wild isolated Carrefour Mme. Gras strain (CMG). Thus, the CMG strain contains a factor that together
with Dp(R2394) produces a synthetic RIP suppressor phenotype. It is possible that the factor is a cryptic Dp that
together with Dp(R2394) can exceed the size threshold for titration of the RIP machinery and thereby causes RIP
suppression.
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Keywords
Chromosome segment duplications, dominant suppressor of RIP, genome defense in fungi
Citation
Ramakrishnan Mukund, Sowjanya T Naga, Raj Kranthi B, Kasbekar Durgadas P. A factor in a wild isolated Neurospora crassa strain enables a chromosome segment duplication to suppress repeat-induced point mutation. Journal of Biosciences. 2011 Dec; 36 (5): 817-821.