Marques André, Pedrosa-Harand Andrea
Laboratory of Genetic Resources, Campus Arapiraca, Federal University of Alagoas, Arapiraca, Alagoas, 57309-005, Brazil.
Laboratory of Plant Cytogenetics and Evolution, Department of Botany, Federal University of Pernambuco, Recife, Pernambuco, 50670-420, Brazil.
Chromosoma. 2016 Sep;125(4):669-81. doi: 10.1007/s00412-016-0612-7. Epub 2016 Aug 16.
The centromere is the chromosomal site of kinetochore assembly and is responsible for the correct chromosome segregation during mitosis and meiosis in eukaryotes. Contrary to monocentrics, holocentric chromosomes lack a primary constriction, what is attributed to a kinetochore activity along almost the entire chromosome length during mitosis. This extended centromere structure imposes a problem during meiosis, since sister holocentromeres are not co-oriented during first meiotic division. Thus, regardless of the relatively conserved somatic chromosome structure of holocentrics, during meiosis holocentric chromosomes show different adaptations to deal with this condition. Recent findings in holocentrics have brought back the discussion of the great centromere plasticity of eukaryotes, from the typical CENH3-based holocentromeres to CENH3-less holocentric organisms. Here, we summarize recent and former findings about centromere/kinetochore adaptations shown by holocentric organisms during mitosis and meiosis and discuss how these adaptations are related to the type of meiosis found.
着丝粒是动粒组装的染色体位点，负责真核生物有丝分裂和减数分裂期间染色体的正确分离。与单着丝粒染色体不同，全着丝粒染色体没有主缢痕，这归因于有丝分裂期间几乎沿着整个染色体长度的动粒活性。这种扩展的着丝粒结构在减数分裂期间带来了一个问题，因为姐妹全着丝粒在第一次减数分裂期间没有共向排列。因此，尽管全着丝粒染色体的体细胞染色体结构相对保守，但在减数分裂期间，全着丝粒染色体表现出不同的适应方式来应对这种情况。全着丝粒染色体的最新发现重新引发了关于真核生物着丝粒巨大可塑性的讨论，从典型的基于CENH3的全着丝粒染色体到无CENH3的全着丝粒生物。在这里，我们总结了全着丝粒生物在有丝分裂和减数分裂期间表现出的着丝粒/动粒适应的近期和以往发现，并讨论了这些适应与所发现的减数分裂类型之间的关系。
