Elucidating Pattern Formation in Anabaena: A Genetic Approach

丝状蓝藻中对氮有反应的鱼腥藻 通过沿半规则间隔的细丝沿着精细加工的剥夺 细胞（异形胞）专门用于N2固定。 的格局 异形胞是由一个抑制场启动和维持的， 从发育和成熟的异形胞中分离出来。 沃尔克博士分离出了变种人 在发育早期就有缺陷， 补充了这些突变体。 研究基因的空间方面 在发育中的纤维中表达，他开发了一种载体， 促进与荧光素酶（lux）的转录融合， 在Anabaena。 他建议：1.进一步发展和 表征使用lux监测来自个体的基因表达 细胞 2. 找出在发育早期表达的基因， 特别是在注定成为异形胞的细胞中。 候选启动子 将融合到勒克斯和光发射沿着灯丝监测 通过发展的过程。 3.实验对象鱼腥藻携带 成功的启动子/lux融合到转座子诱变和反义 RNA表型诱变，以寻找调节 启动子的表达。 这些基因将通过改变 光发射 沃尔克博士将专注于对N- 通过在所有细胞中诱导光发射而不是仅在 发育异形胞。 4.克隆基因，影响表达 启动子，并通过将它们融合到lux中，将它们的表达定位在 时间和空间 高等真核生物从单细胞发展到细胞集合体 不同的类型和功能，但不均匀的分化， 原核生物很少见。 沃尔克博士建议利用 的丝状蓝藻，鱼腥藻，研究这些过程中， 一种简单的原核生物，可以利用强大的遗传技术。

Anabaena in a filamentous cyanobacterium that responds to nitrogen deprivation by elaborating along the filament semi-regularly spaced cells (heterocysts) specialized for N2-fixation. The pattern of heterocysts is initiated amd maintained by an inhibitory field emanating from developing and mature heterocysts. Dr. Wolk has isolated mutants that are defective early in development and have found cosmids that complement certain of these mutants. To study spatial aspects of gene expression in the developing filament, he has developed a vector that facilitates transcriptional fusions to luciferase (lux) and their maintenance in Anabaena. He proposes to: 1. Further develop and characterize the use of lux to monitor gene expression from individual cells. 2. Identify a gene that is expressed early in development, specifically in cells fated to become heterocysts. Candidate promoters will be fused to lux and light emission along the filament monitored through the course of development. 3. Subject Anabaena carrying the successful promoter/lux fusions to transposon mutagenesis and antisense RNA phenotypic mutagenesis to search for genes that regulate the expression of the promoter. Such genes will be identified by altered light emission. Dr. Wolk will focus on mutants that respond to N- stepdown by inducing light emission in all cells rather than only in developing heterocysts. 4. Clone genes that affect the expression of the promoter and, by fusing them to lux, localize their expression in time and space. Higher eukaryotes develop from single cells to collections of cells of varied types and functions, but inhomogeneous differentiation in prokaryotes is rare. Dr. Wolk proposes to exploit the differentiation of the filamentous cyanobacterium, Anabaena, to study these processes in a simple prokaryote where powerful genetic techniques can be utilized.