固氮蓝细菌是既能进行固氮作用又能进行放氧光合作用的原核生物，其中有些丝状种类可以分化产生特化的固氮细胞，称为异形胞。鱼腥蓝细菌PCC7120是异形胞分化常用的研究模式。hetZ是本实验室发现的参与异形胞分化的重要基因，受主调控因子HetR的直接调控。本项申请拟对hetZ调控异形胞分化的机理进行研究，弄清hetZ如何调控分化过程中后续的基因表达，以及hetZ与另一个受HetR直接调控的基因hetP在功能上的关系。利用基因突变、过表达及其组合分析基因之间的关系；利用转录组学方法比较突变株、过表达株与野生型，找到受hetZ影响的基因，并进一步筛选受HetZ直接调控的基因。

N2-fixing cyanobacteria are oxygenic photosynthetic prokaryotes that perform nitrogen fixation. Some groups of filamentous species can produce specialized nitrogen-fixing cells, called heterocysts. Anabaena sp. PCC 7120 is the most often used research model for heterocyst differentiation. hetZ, a gene reported by our group, plays an important role in early heterocyst differentiation. It is directly regulated HetR, the master regulator of heterocyst differentiation. This proposal describes our plan to investigate the mechanism for hetZ to regulate heterocyst differentiation, including how hetZ affects the following gene expression in early heterocyst differentiation, and the relationship of hetZ to hetP, another important gene directly regulated by HetR. Strains of gene inactivation, overexpression or combinations of mutations will be constructed and used to analyze the relationship between genes. Comparative transcriptomic analyses of the wild type/hetZ-null mutant/hetZ-overexpression strain will be performed to find out genes whose expression is affected by hetZ, of which those directly regulated by HetZ will be further identified.