Control of Heterocyst Differentiation in Free-Living and Symbiotic Cyanobacteria

自由生活和共生蓝藻异囊分化的控制

• 批准号: 8902204
• 负责人: John Meeks
• 金额: $ 25.34万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-08-01 至 1992-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8902204&HistoricalAwards=false
• 关键词: Control; Heterocyst; Differentiation; Free; Living

The intent of the project is to identify the biochemical mechanisms that control the differentiation of vegetative cells into heterocysts (sites of aerobic nitrogen fixation) in Nostoc spp. Dr. Meeks hypothesizes that heterocyst differentiation is under control of a global nitrogen regulatory system in the free- living state, that may be superseded by a symbiotic specific system when Nostoc is in association with the bryophyte anthoceros. He proposes to continue characterization and complementation - to identify and isolate regulatory genes involved in heterocyst differentiation. The specific objectives include isolation of additional mutants with the pleiotropic phenotype of inability to grow with nitrate and N2 as nitrogen sources, but able to fix N2 in symbiosis. Such mutants will be characterized by analysis of classes of revertant (single site suppressor mutations). The mutant phenotypes will be complemented by conjugational transfer of wild type or "revertant" DNA cloned in E. coli or packaged in vitro in plasmids and transferred into the Nostoc recipient by electroporation. complementing fragments will be sequenced and compared to established data banks. They will also be used in physiological genetic studies with wild type and mutant strains of Nostoc to define their role in differentiation. %%% This study has implications for two areas. First it is a rare example of pattern formation in bacteria and therefore provides an example to study with the powerful genetic techniques available in bacterial system. Additionally, the cyanobacteria are important components of the environment and play a unique role as primary producers of reduced carbon and nitrogen. An understanding of how these processes are controlled is therefore of general importance.

该项目的目的是确定控制营养细胞分化为Nostoc spp中杂环（有氧氮固定位点）的生化机制。 Meeks博士假设，杂环分化正在控制自由生活状态的全球氮调节系统，当NOSTOC与NOSTOC与苔藓植物植物群相关时，该系统可能被共生特定系统所取代。他建议继续表征和互补 - 识别和分离涉及杂环分化的调节基因。具体目标包括将其他突变体与多效性表型分离，无法用硝酸盐和N2作为氮源生长，但能够在共生中固定N2。这种突变体的特征是分析恢复类（单位位点抑制突变）。突变表型将通过克隆在大肠杆菌中的野生型或“恢复”的DNA的共轭转移或在质粒中包装，并通过电穿孔转移到Nostoc受体中。补充片段将进行测序，并将其与已建立的数据库进行比较。它们还将用于野生型和NOSTOC突变菌株的生理遗传研究中，以定义它们在分化中的作用。 %%％这些研究对两个领域有影响。首先，这是细菌中模式形成的罕见例子，因此提供了一个研究细菌系统中可用的强大遗传技术的例子。此外，蓝细菌是环境的重要组成部分，并且是减少碳和氮的主要生产者的独特作用。因此，对这些过程的控制方式的理解至关重要。