Analysis of gene regulation at the level of higher-order chromatin structure in the soybean leghemoglobin gene locus

豆科植物根瘤中含有受感染和未受感染的细胞，这些细胞在基因表达、倍性、代谢、形态等方面都有区别，本研究以仅在受感染细胞中表达的豆血红蛋白（Lb）基因为研究对象，通过比较受感染和未受感染细胞中Lb基因座的状态，从染色质高级结构水平更好地理解基因调控。主要工作如下：1.获得了两个Lb位点的基因组克隆; 2.建立了从结核中分离细胞核的方法; 3.大部分Lb位点与核基质具有较高的亲和力; 4.获得了大量的布尔斯在Lb基因座中发现了两个碱基互补区，5.建立了分离感染和未感染原生质体的方法，结果表明，Lbc 3基因的甲基化水平较低，对DNase I的敏感性较高，与Lbc 3基因的表达无关，从而获得了有关Lb 3基因染色质结构的基本数据。有些调查结果不一定与以前报告的结果一致。进一步的研究是必要的，以澄清基因表达和染色质结构之间的关系。

Nodules of leguminous plants contain infected and non-infected cells, which are discriminated in gene expression, ploidy, metabolism, morphology and so on. In this work, we focussed on leghemoglobin(Lb)genes which are expressed exclusively in infected cells, to lead a better understanding of gene regulation at the level of higher-order chromatin structure by comparing the state of the Lb locus between infected and non-infected cells. Followings were carried out and clarified.1.We have isolated genomic clones covering two Lb loci.2.We have established the method of the isolation of nuclei from nodules.3.Most of the Lb loci have high affinity with the nuclear matrix.4.A large number of BURs(base-unparing regions)were found in an Lb locus, consistent with the observation that it contained many MARs.5.We have established the method by which protoplasts were isolated from infected and non-infected cells separately.6.Methylation levels in the Lb loci was found to be rather low.7.Sensitivity to DNase I is rather high around the Lbc3 gene irrespective of expression.Thus, we have obtained basic data concerning the chromatin structure of the Lb loci. Some findings are not necessarily consistent with previously reported results. Further investigation is necessary to clarify the relationship between gene expression and chromatin structure.