Genetic Control of Pattern Formation in the Cyanobacterium Anabaena

鱼腥藻是一种丝状蓝藻， 氮剥夺，通过沿丝沿着加工， 有规则间隔的细胞称为异形胞， 用于固氮。这些细胞在反应中分化 到氮的逐步下降可以与那些首先感测到的相同， 氮剥夺;或者如果后者细胞对氮有反应， 通过启动一个连续的清除过程来剥夺 氮形成连续细胞，分化细胞可以是 远离最先感受到氮的细胞 或者，如果分化只是使一个潜在的 （虽然实验上可以操纵）模式，区分 像元与像元之间可能没有一致的空间关系 首先感觉到氮的剥夺。沃尔克博士开发了一种 一系列技术来研究空间和时间方面的问题， 发育中的纤维中的基因表达， 基因对之间的关系。该阵列包括使用 转座子和定点插入， 荧光素酶基因报告个体的活性 启动子沿着细丝一个细胞一个细胞地传递。阐明本 异形胞间距的机制，他建议：1）识别 控制异形胞形成所需的基因， 调节对氮剥夺的早期反应， （2）空间关系;（3）空间关系。 基因激活位点之间的关系 氮剥夺，蚂蚁最终异形胞的位置 形成; 3）确定是否可能转录 充满氮的细丝中的不均匀性具有任何空间 与后续分化的关系;以及4）调查 特殊的实验操作如何影响分化 和模式形成。

Anabaena is a filamentous cyanobacterium that responds to nitrogen deprivation by elaborating along the filaments semi- regularly spaced cells called heterocysts that are specialized for nitrogen fixation. The cells that differentiate in response to nitrogen step down may be the same as those that first sense nitrogen deprivation; or if the latter cells respond to nitrogen deprivation by initiating a sequential process of scavenging nitrogen form contiguous cell, the differentiating cells may be positioned distant from the cells that first sense nitrogen deprivation; or if differentiation merely makes manifest a latent (albeit experimentally manipulable) pattern, the differentiating cells may bear no consistent spatial relationship to the cells first sensing nitrogen deprivation. Dr. Wolk has developed an array of techniques to study spatial and temporal aspects of the expression of genes in the developing filament, and dependency relationships between pairs of genes. This array includes the use of transposons and site directed insertions that incorporate genes for luciferase to report on the activity of individual promoters cell by cell along a filament. To elucidate the mechanism of heterocyst spacing, he proposes to: 1) identify genes required for control of heterocyst formation, genes regulating early responses to nitrogen deprivation, and the dependency relationships among them; 2) elucidate the spatial relationship between the sites of activation of genes in response to nitrogen deprivation, ant the location of eventual heterocyst formation; 3) ascertain whether possible transcriptional inhomogeneities in nitrogen replete filaments bear any spatial relationship to subsequent differentiation; and 4) investigate how particular experimental manipulations affect differentiation and pattern formation.