Mapping chromosome landmarks in the centromere I region of Neurospora crassa.
Chromosome translocation breakpoints, RFLP heterozygosity in partial chromosome duplications, and RFLP-marked crossover events have been used as chromosomal landmarks to find the position and orientation of cloned regions flanking centromere I of Neurospora crassa. Determination of physical:genetic ratios in genomic regions flanking the loci mei-3, un-2, and his-2 supports previous evidence indicating that recombinational activity is lower in regions flanking centromere I than in the general N. crassa genome. The homogeneous distribution of crossover events found in these regions suggests that there is not a gradient of crossover inhibition in the vicinity of centromere I. Thus, a largely extended centromeric effect and/or a general crossover inhibitory effect operating on linkage group I (LGI) could constitute the basis of these abnormal physical:genetic ratios. A DNA element containing about 76% A+T was isolated from the centromeric end of a cloned region on LGIR. The fragment includes a previously undescribed DNA sequence, highly repeated in the Neurospora genome, which may correspond to centromeric DNA.
Rosa
A L
AL
Departamento de Químice Biológica (CIQUIBIC-CONICET), Faculted de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina. alberto@dqbfeq.uncoredu
Haedo
S D
SD
Temporini
E D
ED
Borioli
G A
GA
Mautino
M R
MR
D001482:Base Composition; D001483:Base Sequence; D002503:Centromere; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal; D003434:Crossing Over, Genetic; D017931:DNA Primers; D015723:Gene Library; D005819:Genetic Markers; D016681:Genome, Fungal; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D014178:Translocation, Genetic
D017931:DNA Primers; D005819:Genetic Markers