Analysis of molecular basis between heterochromatin and euchromatin in plant cells

真核生物染色质在显微镜下分为异染色质和常染色质。虽然特定的蛋白质如HP1(异染色质蛋白1)在动物细胞中引起异染色质，但与植物细胞中不同染色质状态有关的因素尚不清楚。因此，在本研究中，我们试图阐明在花粉中决定异染色质和常染色质之间染色质分化的主要因素。这是因为，花粉内的生殖核具有高度浓缩的染色质(异染色质)，而营养核含有弥散的染色质(常染色质)。结果表明，在第一次小孢子有丝分裂后，已被鉴定为雄配子核-高度浓集组蛋白H1的GL1表现出显著的极化。也就是说，在花粉发育过程中，ghl只在生殖核中检测到，并在雄配子核中大量积累。另一方面，在营养核中几乎没有检测到GH1。接下来，克隆了两个组蛋白H1基因GH1和体细胞型组蛋白H1(SH1)，并用RT-PCR方法进行了表达分析。结果表明，虽然SH1的表达在花粉成熟过程中停止，但在第一次小孢子有丝分裂之前，GH1的表达显著增加。因此，GH1被认为是异染色化的一个因素。目前正在通过将基因转移到带有GFP的体细胞中来研究GH1的功能。

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.