Centromeres are chromosomal domains essential for kinetochore assembly and correct chromosome segregation. Inconsistent in their underlying DNA sequences, centromeres are defined epigenetically by the presence of the centromere-specific histone H3 variant CenH3. Most of the analyzed eukaryotes have monocentric chromosomes in which CenH3 proteins deposit into a single, primary constriction visible at metaphase chromosomes. Contrary to monocentrics, evolutionary sporadic holocentric chromosomes lack a primary constriction and have kinetochore activity distributed along the entire chromosome length. In this work, we identified cCENH3 protein, the centromeric H3 histone of the coleopteran model beetle Tribolium castaneum. By ChIP-seq analysis we disclosed that cCENH3 chromatin assembles upon a repertoire of repetitive DNAs. cCENH3 in situ mapping revealed unusually elongated T. castaneum centromeres that comprise approximately 40% of the chromosome length. Being the longest insect regional centromeres evidenced so far, T. castaneum centromeres are characterized by metapolycentric structure composed of several individual cCENH3-containing domains. We suggest that the model beetle T. castaneum with its metapolycentromeres could represent an excellent model for further studies of non-canonical centromeres in insects.

着丝粒是成核细胞组装和正确染色体分离所必需的染色体结构域。着丝粒的基本DNA序列不一致，着丝粒的定义是着丝粒特异性组蛋白H3变体CenH3的存在。大多数分析的真核生物具有单中心染色体，其中CenH3蛋白沉积到单个，在中期染色体上可见的初级缩颈中。与单中心相反，进化的零星全中心染色体缺乏初级收缩，并且在整个染色体长度上均具有线粒体活性。在这项工作中，我们鉴定了cCENH3蛋白，鞘翅目模型甲虫Tribolium castaneum的着丝粒H3组蛋白。通过ChIP-seq分析，我们公开了cCENH3染色质在重复DNA的全部库中组装。cCENH3原位作图揭示异常细长Ť。约占染色体长度的40％的锥栗着丝粒。T是迄今为止证明的最长的昆虫区域着丝粒。拟谷盗着丝粒由几个单独含有cCENH3域组成metapolycentric结构表征。我们认为，该模型甲虫牛逼。盗其metapolycentromeres能代表昆虫不规范的着丝粒的进一步研究的优秀典范。