技术文章

2016年5月26日，植物学期刊《The plant Journal》在线发表了武汉大学生命科学学院交水稻国家重点实验室丁毅教授团队题为“The NnCenH3 Protein and Centromeric DNA Sequence Profiles of Sacred Lotus ( Nelumbo nucifera Gaertn.) Reveal the DNA Structures and Dynamics of Centromeres in Basal Eudicots”的研究论文。论文主要阐述了莲( Nelumbo nucifera Gaertn.)着丝粒蛋白和着丝粒DNA序列的特征。博士生朱之轩为论文*作者，丁毅教授为论文通讯作者。

在细胞有丝分lie和减数分lie时期，着丝粒负责地调控染色体配对与分离并维持染色体的稳定性。由于着丝粒蛋白和着丝粒DNA都具有高度的变异性，这加大了着丝粒蛋白功能和着丝粒进化机制研究的难度。目前，对于基部双子叶植物着丝粒结构的研究未见报道。该项研究以古老的基部双子叶植物莲为材料，克隆并验证了莲着丝粒组蛋白基因NnCenH3，获得了莲着丝粒序列并揭示了莲着丝粒序列的组成特点，为着丝粒结构特征提供了新的认识，该研究结果也将对构建莲基因组精细遗传图和物理地图奠定了基础，并为更好地了解基部双子叶植物着丝粒的进化、揭示着丝粒进化机制提供新线索。

原文链接：

The NnCenH3 Protein and Centromeric DNA Sequence Profiles of Sacred Lotus (Nelumbo nucifera Gaertn.) Reveal the DNA Structures and Dynamics of Centromeres in Basal Eudicots

原文摘要：

Centromeres on eukaryotic chromosomes consist of large arrays of DNA repeats that undergo very rapidevolution. Sacred lotus (Nelumbo nucifera Gaertn.) is a phylogenetic relict and an aquatic perennial basal eudicot. Studies concerning the centromeres of this basal eudicot species could provide ancient evolutionary perspectives. In this study, we characterized the centromeric marker protein NnCenH3 (sacred lotus centromere-specific histone H3 variant) and used a chromatin immunoprecipitation (ChIP)-based technique to recover the NnCenH3 nucleosome-associated sequences of sacred lotus. The properties of the centromere-binding protein and DNA sequences revealed notable divergence between sacred lotus and other flowering plants including the following factors: (1) an NnCenH3 alternative splicing variant comprising only a partial centromere-targeting domain; (2) active genes with low transcription levels in the NnCenH3 nucleosomal regions; and (3) the prevalence of the Ty1/copia class of LTR retrotransposons in the centromeres of sacred lotus chromosomes. In addition, the dynamic natures of the centromeric region showed that some of the centromeric repeat DNA sequences originated from omeric repeats, and a pair of centromeres on the dicentric chromosome 1 was inactive in the metaphase cells of sacred lotus. Our characterization of the properties of centromeric DNA structure within the sacred lotus genome describes a centromeric profile in ancient basal eudicots and might provide evidence of the origins and evolution of centromeres. Furthermore, the identification of centromeric DNA sequences is of great significance for assembly of the sacred lotus genome.