Collaborative Research: RUI: Mathematical and empirical investigation of a reaction-diffusion system for spot formation in hybrid Mimulus

地球上的生命呈现出一系列令人眼花缭乱的模式。它们的范围从内部模式，如脊髓中椎骨的重复，到外部模式，如斑马身上的黑色条纹。关于这些模式是如何形成的，有两种观点。“位置规范”模型认为，这些模式是由一组基因在特定位置以一种受控制的方式被激活而产生的。“反应-扩散”模型认为，模式可以从相互作用的基因的自组织系统中产生。根据第二种模型，每个模式成分的位置是由一个基因活性水平的随机波动决定的。网络中的其他基因对第一个基因作出反应，产生构成图案单元所需的元素。一些特征，如猕猴桃属的花瓣斑点，似乎依赖于两种类型的模式形成。这个花瓣-斑点系统被用来研究位置规范和反应-扩散，以及它们如何相互作用，在自然界中创造新的、复杂的图案。该合作项目为1名博士生和18名本科生创造了研究机会。三名高中学生将从西澳沃拉沃拉农村的一所公立学校招募，这所学校专门为那些不经常接触科学经验的年轻人提供服务。先前的研究已经证实，红色花青素的花蜜引导点的形成方式与反应扩散系统相一致。在拟南芥与黄豆变种杂交种的花瓣裂片中精细斑点模式的发现创造了一个独特的机会来研究(a)这种反应扩散系统是否更普遍地解释了拟南芥的花模式，(b)来自花瓣脉管系统的位置线索是否塑造了这些模式，以及(c)与杂交相关的基因组间相互作用如何产生在任何亲本物种中都没有见过的新表型。研究人员将首先开发一种反应扩散模型，以重现在杂交F2遗传作图群体中观察到的花青素斑点表型的分布。他们将通过检查重组自交系群体中存在的各种纯合子基因型，并使用转基因操作来改变花青素调节网络中关键基因的表达，来测试该模型。最后，他们将研究花瓣血管系统影响斑点形成位置的假设。这将通过使用数字图像分析和空间统计来测试斑点和静脉位置之间的相关性，并通过化学和转基因扰动实验操纵静脉发育来测试对斑点形成的影响来实现。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Life on earth exhibits a dazzling array of patterns. These range from internal patterns, like the repetition of vertebrae in the spinal cord, to external patterns like the stripes of black pigment on a zebra. There are two ideas about how these patterns might form. The “positional specification” model is that the patterns are created by a set of genes being turned on in specific locations in a controlled fashion. The “reaction-diffusion” model is that patterns can arise from a self-organizing system of interacting genes. According to this second model, the location of each pattern component is determined by random fluctuations in one gene’s activity level. Other genes in the network respond to the first gene to create the elements needed for making a unit of the pattern. Some traits, such as petal spots in the monkeyflower genus Mimulus, appear to depend on both types of pattern formation. This petal-spot system is being used to study both positional specification and reaction-diffusion, and how they interact to create new, complex patterns in nature. The collaborative project creates research opportunities for one Ph.D. student and eighteen undergraduates. Three high school students will be recruited from a public school in rural Walla Walla, WA that specifically serves youth not routinely exposed to scientific experiences. Previous work in Mimulus has established that nectar guide spots of red anthocyanin pigment are formed in a manner consistent with a reaction-diffusion system. The discovery of elaborate spot patterns in the petal lobes of Mimulus cupreus x M. luteus var. variegatus hybrids creates a unique opportunity to examine (a) whether this reaction-diffusion system explains floral patterning in Mimulus more generally, (b) whether positional cues originating from petal vasculature shape these patterns, and (c) how the inter-genomic interactions associated with hybridization can generate novel phenotypes not seen in either parent species. The researchers will first develop a reaction-diffusion model that recreates the distribution of anthocyanin spotting phenotypes observed in a hybrid F2 genetic mapping population. They will test this model by examining the diverse sets of homozygous genotypes present in a Recombinant Inbred Line population, and by using transgenic manipulation to alter the expression of key genes in the anthocyanin regulatory network. Finally, they will investigate the hypothesis that petal vasculature influences the location of spot formation. This will be achieved by using digital image analysis and spatial statistics to test for correlations between spot and vein locations, and experimentally manipulating vein development through chemical and transgenic perturbations to test for effects on spot formation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.