Jin Weiwei, Lamb Jonathan C, Zhang Wenli, Kolano Bozena, Birchler James A, Jiang Jiming
Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA.
Chromosome Res. 2008;16(8):1203-14. doi: 10.1007/s10577-008-1269-8. Epub 2008 Nov 8.
We report the distribution of several histone modifications along the arms and in centromeric regions of somatic chromosomes of maize, including the supernumerary B chromosome. Acetylated H3 and H4 as well as H3K4me2, modifications associated with euchromatin, were enriched in the distal parts of the A chromosomes, but were progressively depleted toward the centromeres of the A chromosomes and were depleted in the heterochromatic portions of the B chromosome. Classical histone modifications associated with heterochromatin, including H3K9me2, H3K27me1 and H3K27me2, were distributed throughout both A and B chromosomes. However, H3K27me2 showed a reduced level on the B chromosome compared with the A chromosomes and was not associated with some classes of constitutive heterochromatin. We monitored the presence of each histone modification in the centromeric regions using a YFP-tagged centromere-specific histone, CENH3. We observed the presence of H3K9me2 and absence of H3K4me2 in the centromeric regions of both A and B chromosomes of maize, which is in contrast to the presence of H3K4me2 and absence of H3K9me2 in animal centromeres. These results show a diversity of epigenetic modifications associated with centromeric chromatin in different eukaryotes.
我们报告了几种组蛋白修饰在玉米体细胞染色体（包括额外的B染色体）的臂和着丝粒区域的分布情况。与常染色质相关的乙酰化H3和H4以及H3K4me2修饰在A染色体的远端部分富集，但朝着A染色体的着丝粒逐渐减少，并且在B染色体的异染色质部分缺失。与异染色质相关的经典组蛋白修饰，包括H3K9me2、H3K27me1和H3K27me2，分布在A和B染色体上。然而，与A染色体相比，H3K27me2在B染色体上的水平降低，并且与某些组成型异染色质类别无关。我们使用黄色荧光蛋白标记的着丝粒特异性组蛋白CENH3监测了着丝粒区域中每种组蛋白修饰的存在情况。我们观察到玉米A和B染色体的着丝粒区域存在H3K9me2且不存在H3K4me2，这与动物着丝粒中存在H3K4me2且不存在H3K9me2的情况相反。这些结果表明不同真核生物中与着丝粒染色质相关的表观遗传修饰具有多样性。
