植物著絲粒含有大量的重復序列和反轉座子，結構復雜并受表觀遺傳學調控。中科院遺傳與發(fā)育生物學研究所韓方普實驗室長期從事植物著絲粒的表觀遺傳學研究，曾在植物中首次發(fā)現(xiàn)著絲粒的失活現(xiàn)象并初步分析失活著絲粒的調控機制。

　　由于著絲粒的特殊表觀遺傳學調控機制，植物著絲粒的DNA序列暫不能直接用于植物人工染色體的構建。這也是植物人工染色體構建方法不同于人類等人工染色體的策略。為了更好地研究植物著絲粒的結構與功能，特別是著絲粒是如何形成的？該實驗室利用玉米三號染色體特殊材料，發(fā)現(xiàn)來自玉米三號染色體的片段可以穩(wěn)定遺傳并沒有檢測到玉米著絲粒的重復序列（CentC和CRM）。但具有著絲粒功能分子標記如CENH3和CENPC以及組蛋白磷酸化的信號。CENH3-ChiP-Seq分析結果表明玉米3號染色體長臂上一段常染色質區(qū)域（區(qū)域大小為350kb）參與并形成了功能著絲粒，序列分析350kb區(qū)域含有22個基因，其中11個基因與CENH3緊密結合。

　　該研究結果于3月25日在PNAS在線發(fā)表（DOI:10.1073/pnas.1303944110），韓方普實驗室博士后符書蘭和工作人員呂振玲為本文的共同第一作者。本項工作同JamesBirchler和王秀杰實驗室共同合作完成。

　　該研究得到科技部重大研究計劃、國家自然科學基金委重點項目和中國科學院的資助。

論文摘要
　
　                                                                        

      De novo centromere formation on a chromosome fragment in maize

The centromere is the part of the chromosome that organizes the kinetochore, which mediates chromosome movement during mitosis and meiosis. A small fragment from chromosome 3, named Duplication 3a (Dp3a), was described from UV-irradiated materials by Stadler and Roman in the 1940s [Stadler LJ, Roman H (1948) Genetics 33(3):273–303]. The genetic behavior of Dp3a is reminiscent of a ring chromosome, but fluoresecent in situ hybridization detected telomeres at both ends, suggesting a linear structure. This small chromosome has no detectable canonical centromeric sequences, but contains a site with protein features of functional centromeres such as CENH3, the centromere specific H3 histone variant, and CENP-C, a foundational kinetochore protein, suggesting the de novo formation of a centromere on the chromatin fragment. To examine the sequences associated with CENH3, chromatin immunoprecipitation was carried out with anti-CENH3 antibodies using material from young seedlings with and without the Dp3a chromosome. A novel peak was detected from the ChIP-Sequencing reads of the Dp3a sample. The peak spanned 350 kb within the long arm of chromosome 3 covering 22 genes. Collectively, these results define the behavior and molecular features of de novo centromere formation in the Dp3a chromosome, which may shed light on the initiation of new centromere sites during evolution.

　　作者：ShulanFua,1,ZhenlingLva,1,ZhiGaob,1,HuajunWuc,JunlingPangc,BingZhanga,QianhuaDonga,XiangGuoa,Xiu-JieWangc,JamesA.Birchlerb,2,andFangpuHana,2

　　期刊名稱：Proceedings of the National Academy of Sciences

　　期卷頁：第卷第期~頁

　　學科領域：生命科學?植物學?植物生理與生化

　　添加人是否為作者:否

　　原文鏈接：http://www.pnas.org/content/early/2013/03/20/1303944110

　　DOI：10.1073/pnas.1303944110

　　ISBN：0027-8424

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　　相關報道：http://paper.sciencenet.cn/htmlpaper/20134715524273028714.shtm

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