title: An apparent increase in meiotic silencing strength in crosses involving inbred Neurospora crassa strains.
abstract: Meiotic silencing by unpaired DNA is a presumed RNAi-mediated elimination of the transcripts of any gene that is not properly paired with a homolog in meiosis. Wild-isolated strains of Neurospora crassa can be classified into three types based on the apparent strength of meiotic silencing of the bml (β-tubulin) and mei-3 genes in crosses of the wild strains with the tester strains ::Bml(r) and ::mei-3. Crosses with "OR" and "Sad" type wild-isolates, respectively, did or did not silence both the genes, whereas crosses with the "Esm" type silenced bml, but not mei-3(+). Presumably, bml is more sensitive to silencing than mei-3, and silencing is strongest in crosses with the OR type, weakest (or non-evident) in crosses with the Sad type, and of intermediate strength in crosses with Esm type. Now, while constructing recombinant inbred lines from the Sad type wild strains Bichpuri-1 a and Spurger-3 A, we found that although crosses of Bichpuri-1 a and Spurger-3 A, and of most of their f1 progeny, with the ::Bml(r) and ::mei-3 testers were consistently and reproducibly Sad type, those of later generation strains of each line could show Sad, Esm, or a variably expressive Sad/Esm type. Since any genotype found in a later generation is, in principle, obtainable in the f1, the observed transition from an apparently stable Sad phenotype to an apparently unstable Sad/Esm phenotype appears not to be due to genotype differences between the generations. Therefore, the Sad versus Esm difference may have a genotype-independent basis.
authors.affiliation: Centre for Cellular and Molecular Biology, Hyderabad 500 007, India.
authors.forename: T
authors.initials: T
authors.lastname: Nagasowjanya
authors.forename: Kranthi B
authors.initials: KB
authors.lastname: Raj
authors.forename: K
authors.initials: K
authors.lastname: Sreethi Reddy
authors.forename: Durgadas P
authors.initials: DP
authors.lastname: Kasbekar
mesh_terms: D003433:Crosses, Genetic; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D020868:Gene Silencing; D005838:Genotype; D008540:Meiosis; D009492:Neurospora crassa / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D014404:Tubulin / Q000096:biosynthesis / Q000235:genetics
chemical_list: D005656:Fungal Proteins; C083569:MEI-3 protein, Neurospora crassa; D014404:Tubulin