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    • Keywords

       

      Chromosome segment duplications; incomplete penetrance; insertional and quasiterminal translocations; meiotic silencing of unpaired DNA; repeat-induced point mutation

    • Abstract

       

      In Neurospora crassa, crosses between normal sequence strains and strains bearing some translocations can yield progeny bearing a duplication (Dp) of the translocated chromosome segment. Here, 30 breakpoint junction sequences of 12 Dp-generating translocations were determined. The breakpoints disrupted 13 genes (including predicted genes), and created 10 novel open reading frames. Insertion of sequences from LG III into LG I as translocation T(UK818) disrupts the eat-3 gene, which is the ortholog of the Podospora anserine gene ami1. Since ami1-homozygous Podospora crosses were reported to increase the frequency of repeat-induced point mutation (RIP), we performed crosses homozygous for a deficiency in eat-3 to test for a corresponding increase in RIP frequency. However, our results suggested that, unlike in Podospora, the eat-3 gene might be essential for ascus development in Neurospora. Duplication–heterozygous crosses are generally barren in Neurospora; however, by using molecular probes developed in this study, we could identify Dp segregants from two different translocation–heterozygous crosses, and using these we found that the barren phenotype of at least some duplication–heterozygous crosses was incompletely penetrant.

    • Author Affiliations

       

      Parmit K Singh1 Srividhya V Iyer1 T Naga Sowjanya1 B Kranthi Raj1 Durgadas P Kasbekar1

      1. Centre for Cellular and Molecular Biology, Hyderabad 500 007, India
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