Swimming, Swarming, or Sticking in Vibrio Parahaemolyticus

智力优势 细菌是选择在液体中游动，诱导特定的群集细胞程序以便在表面上移动和定居，还是变得不那么移动的而更具粘性以形成生物膜，是什么调控过程决定的？ 海洋细菌副溶血性弧菌是解决这个问题的一个很好的模式生物，因为游泳，群集和粘性生物膜熟练的细胞之间的区别是非常深刻的这种生物。 表面相关生长促进基因表达的全球性、全基因组重编程，导致细胞类型改变，并诱导一个全新的运动系统，该系统不由游泳细胞表达。 这种交替的系统允许在表面上非常快速的移动，这被称为群集。 表面上的生长也可导致稳健的生物膜形成。 已经鉴定了响应于表面上的生长而被微调控的基因集;特别是运动性和粘附性基因以及支配这些基因集的表达的调控基因。 这些被命名为scr的调控基因编码含有GGDEF和EAL特征结构域的潜在信号转导蛋白，其具有引起信号核苷酸c-di-GMP合成和降解的酶活性。 该项目的重点是c-di-GMP在编程基因表达和行为中的作用。 假设Scr信号转导蛋白的特定阵列能够通过调节c-di-GMP的水平来检测和整合不同的环境信号，从而影响群集或粘附的决定。 低浓度的c-di-GMP有利于表面流动性;而高水平的这种核苷酸促进更具粘附性和固着性或生物膜活性的细胞类型。 该项目的重点是：1、通过使用基因筛选来检测潜在的scr传感器和荧光融合蛋白以确定蛋白质定位，从而限定scr c-di-GMP网络的范围;以及2、通过检查群集和粘附的候选转录调节因子，建立c-di-GMP控制基因表达的分子基础。 因此，这项研究旨在绘制一个复杂的调控回路，控制细菌在其环境中感知、整合和响应多种信号的过程，并将深入了解细菌如何做出决策。 这些研究将揭示使细菌能够成功定植表面的发育程序的一般原则，并表明副溶血性弧菌所利用的特定表面适应策略。 该项目是专门设计的，通过实施本科生驱动的发现项目来整合教学和研究，以检查环境信号输入并定义新的输出目标。 这个发现计划将允许本科生直接参与研究过程。 学生将学习进行观察，制定假设和测试他们的想法;他们还将发展自己的写作和公开演讲技巧。 重要的是，学生的项目是以这样一种方式制定的，学生也将获得广泛的遗传，生理，分子生物学和生物信息学为基础的技术，可以应用于解开基因控制和细菌行为的基础程序库的知识。

Intellectual Merit What regulatory processes govern whether a bacterium chooses to swim in liquid, to induce the specific swarmer cell program in order to move over and colonize surfaces, or to become less mobile and more adhesive in order to form biofilms? The marine bacterium Vibrio parahaemolyticus is an excellent model organism in which to address this question because the distinctions between the swimming, swarming, and sticky biofilm-proficient cells are very profound for this organism. Surface-associated growth promotes global, genome-wide reprogramming of gene expression resulting in an altered cell type and the induction of an entirely new motility system that is not expressed by the swimmer cell. This alternate system allows extremely rapid movement over surfaces, which is called swarming. Growth on surfaces can also result in robust biofilm formation. Gene sets have been identified that are reciprocally regulated in response to growth on surfaces; specifically motility and adhesive genes as well as the regulatory genes that govern the expression of these gene sets. These regulatory genes, named scr, encode potential signal transduction proteins containing GGDEF and EAL signature domains, which possess enzymatic activities causing synthesis and degradation of the signaling nucleotide c-di-GMP. This project focuses on the role of c-di-GMP in programming gene expression and behavior. It is hypothesized that a specific array of Scr signal transducing proteins, capable of detecting and integrating diverse environmental signals by modulating the level of c-di-GMP, influences the decision to swarm or stick. A low concentration of c-di-GMP favors surface mobility; whereas high levels of this nucleotide promote a more adhesive and sessile, or biofilm-proficient, cell type. This project focuses on: 1, defining the scope of the scr c-di-GMP network by using genetic screens to detect potential scr sensors and fluorescent fusion proteins to determine protein localization; and 2, establishing the molecular basis of c-di-GMP control of gene expression by examining candidate transcriptional regulators of swarming and sticking. Thus, this research is designed to map a complex regulatory circuit controlling processes by which bacteria sense, integrate, and respond to multiple signals in their environment, and will provide insight into how bacteria make decisions.Broader Impact These studies will reveal general principles with respect to the developmental program that enables bacteria to successfully colonize surfaces, as well as indicate the specific surface-adaptation strategies utilized by V. parahaemolyticus. This project is specifically designed to integrate teaching and research by implementing an undergraduate-driven discovery project to examine environmental signal input and define new output targets. This discovery plan will allow the direct participation of undergraduate students in the research process. Students will learn to make observations, formulate hypotheses and test their ideas; they will also develop their writing and public speaking skills. Importantly, the student projects are formulated in such a manner that the students will also gain knowledge of the broad arsenal of genetic, physiological, molecular biological, and bioinformatics-based techniques that can be applied to unravel programs of gene control and the underlying basis for bacterial behavior.