title: High density analysis of randomly selected Neurospora octads reveals conversion associated with crossovers located between cog and his-3.
abstract: We analysed 148 octads from a Neurospora cross maximised for sequence heterology in the his-3 region and detected non-Mendelian segregation at his-3, cot-1 and lys-4 loci. This was in all cases 6:2 or 2:6, with no evidence of post-meiotic segregation (PMS) in these genes. High density snp analysis was used to place crossovers between his-3 and the centromere-distal marker ad-3, and sequencing to refine the location of crossovers between his-3 and the recombination hotspot cog. Crossovers appeared to have a non-random distribution, falling close to his-3 or more than 40 kb distal, and all those in which the location was determined were flanked by sequences showing gene conversion and/or PMS amongst the polymorphisms. This octad study confirms the validity of assumptions made during random spore analyses and suggests that recombination hotspots at cot-1 and lys-4 may, unlike the relatively cold recombination initiator at the am locus, be high frequency recombinators similar to cog.
authors.affiliation: School of Biological Sciences, Flinders University, PO Box 2100, Adelaide, South Australia 5001, Australia.
authors.forename: P Jane
authors.initials: PJ
authors.lastname: Yeadon
authors.forename: F J
authors.initials: FJ
authors.lastname: Bowring
authors.forename: D E A
authors.initials: DE
authors.lastname: Catcheside
mesh_terms: D003434:Crossing Over, Genetic; D005785:Gene Conversion; D005800:Genes, Fungal; D009491:Neurospora / Q000235:genetics*