School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia.
Genes (Basel). 2021 Aug 26;12(9):1320. doi: 10.3390/genes12091320.
Chromosome segregation at mitosis and meiosis is a highly dynamic and tightly regulated process that involves a large number of components. Due to the fundamental nature of chromosome segregation, many genes involved in this process are evolutionarily highly conserved, but duplications and functional diversification has occurred in various lineages. In order to better understand the evolution of genes involved in chromosome segregation in mammals, we analyzed some of the key components in the basal mammalian lineage of egg-laying mammals. The chromosome passenger complex is a multiprotein complex central to chromosome segregation during both mitosis and meiosis. It consists of survivin, borealin, inner centromere protein, and Aurora kinase B or C. We confirm the absence of Aurora kinase C in marsupials and show its absence in both platypus and echidna, which supports the current model of the evolution of Aurora kinases. High expression of , an ancestor of and present in monotremes, suggests that this gene is performing all necessary meiotic functions in monotremes. Other genes of the chromosome passenger complex complex are present and conserved in monotremes, suggesting that their function has been preserved in mammals. Cohesins are another family of genes that are of vital importance for chromosome cohesion and segregation at mitosis and meiosis. Previous work has demonstrated an accumulation and differential loading of structural maintenance of chromosomes 3 (SMC3) on the platypus sex chromosome complex at meiotic prophase I. We investigated if a similar accumulation occurs in the echidna during meiosis I. In contrast to platypus, SMC3 was only found on the synaptonemal complex in echidna. This indicates that the specific distribution of SMC3 on the sex chromosome complex may have evolved specifically in platypus.
有丝分裂和减数分裂中的染色体分离是一个高度动态和严格调控的过程，涉及到大量的成分。由于染色体分离的基本性质，许多参与这个过程的基因在进化上是高度保守的，但在不同的谱系中发生了重复和功能多样化。为了更好地理解哺乳动物中参与染色体分离的基因的进化，我们分析了卵生哺乳动物的基础哺乳动物谱系中的一些关键成分。染色体乘客复合物是一个在有丝分裂和减数分裂过程中对染色体分离至关重要的多蛋白复合物。它由 survivin、borealin、内着丝粒蛋白和 Aurora 激酶 B 或 C 组成。我们确认在有袋动物中不存在 Aurora 激酶 C，并显示其在鸭嘴兽和针鼹中也不存在，这支持了目前的 Aurora 激酶进化模型。在单孔目动物中高度表达的 ，是 和 的祖先，这表明该基因在单孔目动物中执行所有必要的减数分裂功能。染色体乘客复合物的其他基因也存在于单孔目动物中并保守，这表明它们的功能在哺乳动物中得到了保留。着丝粒蛋白也是一个对有丝分裂和减数分裂中染色体凝聚和分离至关重要的基因家族。以前的工作已经证明，在减数分裂前期 I 中，结构维持染色体 3（SMC3）在鸭嘴兽性染色体复合物上的积累和差异加载。我们研究了在单孔目动物的减数分裂 I 中是否会发生类似的积累。与鸭嘴兽不同，SMC3 仅在单孔目动物的联会复合体上被发现。这表明 SMC3 在性染色体复合物上的特定分布可能是在鸭嘴兽中特异地进化而来的。
