The Analysis of Distribution: Centromere Coorientation
Although distribution is the only one of the three central elements of meiosis generally accessible to direct analysis, it has not received nearly as much attention in the literature as chromosome pairing and crossing-over. A major reason is undoubtedly the fact that relatively little variation from randomness is observed in chromosomes not mechanically connected, especially in diploids. A few exceptions have been noted, with indications of “affinity” and “distributive pairing”. Lack of satisfactory markers is a second reason. Univalent segregation in haploids and species hybrids, and trivalent segregation in triploids has been studied somewhat more frequently, and sometimes deviations from random distribution systems can be quantitatively described, if not explained. More details are available on the segregation of chromosomes associated in multivalents, but even here the complexity of the phenomena makes it difficult to design satisfactory models on the basis of which quantitative interpretations of the observations can be given.
KeywordsAlternate Orientation Chiasma Frequency Metacentric Chromosome Balance Spore Translocation Heterozygote
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