Shaw D D, Knowles G R
Chromosoma. 1976 Dec 16;59(2):103-27. doi: 10.1007/BF00328480.
A new computerised technique has been devised for measuring the distribution of chiasmata along diplotene bivalents. The method involves the introduction into the field of view of the microscope, of a fine light spot which can be accurately manipulated along the chromosomes of each bivalent. The data recorded include (a) the positions of the chiasmata along the bivalent in terms of their relative distances from the centromere and (b) the individual bivalent and cellular chiasma frequencies. -- The method has been applied to the analysis of chiasma distribution patterns in the two known species of the genus Caledia, C. species nova 1 and C. captiva and in two chromosomal races of the latter. Statistical tests indicate that within bivalents at least 40% of the comparative distribution patterns of chiasmata between races and species are significantly different. Similar comparisons between populations within races reveal only 18% significant differences. -- The observed distribution patterns of chiasmata in this genus suggest that chiasma formation is sequential from centromere to telomere. -- The variation in the frequency and distribution of chiasmata between races and species suggests that the interference distances between successive chiasmata are, at least partially, independent of chiasma frequency and position. -- The interracial and interspecific differences in chromosome structure are correlated with changes in chiasma pattern.
已设计出一种新的计算机技术来测量交叉在双线期二价体上的分布情况。该方法包括在显微镜视野中引入一个精细的亮点，这个亮点可以沿着每个二价体的染色体精确操控。记录的数据包括：（a）交叉沿着二价体的位置，以它们距着丝粒的相对距离表示；（b）各个二价体和细胞的交叉频率。——该方法已应用于分析卡勒迪亚属已知的两个物种，即新物种1和俘虏种以及后者的两个染色体族中的交叉分布模式。统计检验表明，在二价体内，种族和物种之间交叉的比较分布模式至少40%有显著差异。种族内种群之间的类似比较仅显示18%有显著差异。——在该属中观察到的交叉分布模式表明，交叉形成是从着丝粒到端粒依次进行的。——种族和物种之间交叉频率和分布的变化表明，连续交叉之间的干涉距离至少部分独立于交叉频率和位置。——染色体结构的种间和种内差异与交叉模式的变化相关。
