Rosa A L, Haedo S D, Temporini E D, Borioli G A, Mautino M R
Departamento de Químice Biológica (CIQUIBIC-CONICET), Faculted de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
Fungal Genet Biol. 1997 Jun;21(3):315-22. doi: 10.1006/fgbi.1997.0987.
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.
染色体易位断点、部分染色体重复中的限制性片段长度多态性（RFLP）杂合性以及RFLP标记的交叉事件已被用作染色体标记，以寻找粗糙脉孢菌着丝粒I侧翼克隆区域的位置和方向。对位于mei-3、un-2和his-2基因座侧翼基因组区域的物理：遗传比率的测定支持了先前的证据，表明着丝粒I侧翼区域的重组活性低于粗糙脉孢菌的一般基因组。在这些区域发现的交叉事件的均匀分布表明，着丝粒I附近不存在交叉抑制梯度。因此，作用于连锁群I（LGI）的广泛延伸的着丝粒效应和/或一般交叉抑制效应可能构成这些异常物理：遗传比率的基础。从LGIR上一个克隆区域的着丝粒末端分离出一个含有约76% A+T的DNA元件。该片段包含一个先前未描述的DNA序列，在脉孢菌基因组中高度重复，可能对应着丝粒DNA。
