Analysis of molecular basis between heterochromatin and euchromatin in plant cells

真核染色质在显微镜下分为异染色质和常染色质。尽管在动物细胞中，HP1（异染色质蛋白1）等特定蛋白会引起异染色质，但与植物细胞中不同染色质状态相关的因素尚不清楚。因此，在本研究中，我们试图阐明花粉异染色质和常染色质分化的主要因素。因为，花粉中的生殖核具有高度凝聚的染色质（异染色质），而营养核含有弥散染色质（常染色质）。结果表明，被鉴定为雄性配子核-高浓度组蛋白H1的gHl在第一次小孢子有丝分裂后出现了显著的极化。即gHl仅在生殖核中检测到，在花粉发育过程中大量积累在雄性配子体核中。另一方面，gH1在营养细胞核中几乎没有检测到。然后，分离组蛋白H1 gH1和体细胞型组蛋白H1 （sH1）两个基因，采用RT-PCR方法进行表达分析。结果表明，sH1的表达在花粉成熟过程中停止，而gH1的表达从第一次小孢子有丝分裂前开始显著增加。因此，gH1被认为是异色化的一个因素。gH1的功能目前正在研究通过基因转移到体细胞与GFP。

Eukaryotic chromatin is microscopically classified into heterochromatin and euchromatin. Although specific proteins such as HP1 (heterochromatin protein 1) give rise to heterochromatin in animal cells, the factors relating to different chromatin states in plant cells remain unclear. So, in this study, we tried to clarify the major factor to determine the chromatin differentiation between heterochromatin and euchromatin in the case of pollen. Because, the generative nucleus within pollen has highly condensed chromatin (heterochromatin), whereas the vegetative nucleus contains diffuse chromatin (euchromatin).As a result, it was demonstrated that gHl, which had been identified as male gametic nucleus-highly concentrated histone H1, showed a remarkable polarization just after the first microspore mitosis. Namely, gHl was only detected in the generative nucleus and largely accumulated in the male gametic nucleus during pollen development. On the other hand, gH1 was barely detected in the vegetative nucleus. Next, two histone H1 genes, gH1 and somatic type-histone H1 (sH1), were isolated and expression analysis was done by RT-PCR method. As a result, while the expression of sH1 came to a stop during pollen maturation, the expression of gH1 remarkably increased from just before the first microspore mitosis. Accordingly, gH1 was assumed as a factor of heterochromatization. The function of gH1 is now investigating by gene transfer into somatic cells with GFP.