Pandey P, Houben A, Kumlehn J, Melzer M, Rutten T
Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.
Cytogenet Genome Res. 2013;141(1):50-7. doi: 10.1159/000351211. Epub 2013 May 30.
The dynamics of posttranslational histone modifications in relation to nuclear architecture has been analyzed during pollen development in Hordeum vulgare L. cv. Igri. Notwithstanding the asymmetry of cytokinesis associated with pollen mitosis I, immunolabeling revealed that the vegetative and generative nuclei initially display identical chromatin modification patterns. Yet, differential chromatin modification patterns between vegetative and generative nuclei emerge with the development of conspicuous differences in nuclear morphology as visualized by 4',6-diamidino-2-phenylindole staining. The temporal and spatial distribution of most histone modifications observed is in agreement with reduced gene activity in the generative nucleus and increased expression in the vegetative nucleus as indicated by immunolabeling of active RNA polymerase II. Signals of trimethylation of histone H3 lysine 27 proved to be particularly enriched in euchromatic domains of subtelomeric regions. In the context of nuclear differentiation in bicellular pollen, this modification became restricted to the vegetative nucleus, indicating a role in activating rather than suppressing gene expression. The presence of acetylated histone H3 at lysine 9 in the cytoplasm of the generative cell is indicative of a more complex, still unknown function of this particular modification.
在大麦品种Igri的花粉发育过程中，已对与核结构相关的翻译后组蛋白修饰动态进行了分析。尽管与花粉有丝分裂I相关的胞质分裂不对称，但免疫标记显示，营养核和生殖核最初呈现相同的染色质修饰模式。然而，随着通过4',6-二脒基-2-苯基吲哚染色观察到的核形态出现明显差异，营养核和生殖核之间出现了不同的染色质修饰模式。观察到的大多数组蛋白修饰的时空分布与生殖核中基因活性降低以及营养核中表达增加一致，这通过活性RNA聚合酶II的免疫标记得以表明。组蛋白H3赖氨酸27三甲基化信号在亚端粒区域的常染色质结构域中特别富集。在二细胞花粉的核分化背景下，这种修饰仅限于营养核，表明其在激活而非抑制基因表达中起作用。生殖细胞细胞质中赖氨酸9处乙酰化组蛋白H3的存在表明这种特定修饰具有更复杂、尚不清楚的功能。
