RUI: Control of Branching in Neurospora Crassa

在大多数丝状真菌中，粗神经孢子菌的生长始于高度极化的细胞扩展，导致直径均匀的菌丝管的形成。不断扩展的尖端发出周期性分支，这些分支本身具有扩展和分支的能力。很少有其他生物系统以这种方式发展。新枝通常出现在延伸尖端的顶端后一小段距离，并与主菌丝成一定角度生长，称为“侧枝”。在正常情况下，大多数分支点横向形成，但在少数分支点上可以看到交替的分支形态。在这种少数形态中，两个尖端以与先前生长方向成一定角度出现，形成分叉结构。这些被称为“二分”或“顶端”分支点。在本项目中，将研究分枝形态控制的遗传学。该项目将重点关注在粗神经孢子虫中观察到的侧向/二分二态性。该项目预计将沿着两条独立的战线推进。首先，形态学突变的收集将通过筛选一组已知形态学突变的抑制子来扩大。在项目的这个阶段，重点将放在导致有利于二分类分支的转变的突变上。这有望揭示作用于特定分支突变体的抑制子，并有望恢复那些能够至少部分抑制分支效应的更广泛的形态突变选择，实际上，作为低分支突变体。这种突变在神经孢子虫中基本上是未知的。其次，将进一步研究冷休克的形态学影响。在神经孢子菌中，温度的变化（25℃到4℃）已被证明会引起戏剧性的，但暂时的分支效应。响应的一个阶段的特征是形态学上的切换到所有二分类分支。通过筛选对冷休克反应改变的突变体，应该确定负责分支形态之间发育转换的基因。丝状真菌在人类事务中扮演着重要的角色。它们是生物质的主要回收者，也是农业和木材生产损失的重要来源，是病原体和腐败剂。它们既影响生产者（产品损失、抗真菌作用的成本），也影响消费者（成本增加、食品变质、木制品分解），因此具有重大的经济影响。增加我们对真菌的尖端生长和分支的了解将有助于更直接地控制生物体的生长。该项目将被证明对批量培养技术有用，真菌在材料中受到温度变化的控制，并应扩大我们对丝状真菌生长的了解。

0233242WattersAs in most filamentous fungi, growth of Neurospora crassa begins by highly polarized cell extension that leads to the formation of a hyphal tube of uniform diameter. The continuously extending tip sends off periodic branches, which are themselves, capable of extension and branching. There are few other biological systems that develop in this manner. New branches normally emerge a short distance behind the apex of the extending tip and grow at an angle to the main hypha and are referred to as 'lateral' branches. Under normal conditions the majority of branch points form laterally, but alternate branch morphology is seen at a minority of branch points. In this minority morphology, the two tips emerge at an angle to the previous direction of growth forming a forked structure. These are referred to as 'dichotomous' or 'apical' branch points. In this project, the genetics of control of branch morphology will be examined. The project will focus on the lateral/dichotomous dimorphism observed in Neurospora crassa. The project is expected to advance along two independent fronts. First, the collection of morphological mutations will be expanded by screening for suppressors of a select group of known morphological mutations. In this phase of the project, the focus will be on mutations that cause a shift in favor of dichotomous branching. This is expected to uncover suppressors which act on specific branching mutants, and hopefully will also recover those which are capable of at least partially suppressing the branching effect on a wider selection of morphological mutations, acting, in effect, as low-branching mutants. Such mutations are largely unknown in Neurospora. Second, the morphological effects of cold shock will be further examined. In Neurospora, temperature shifts (25 to 4) have been shown to cause a dramatic, but temporary branching effect. One phase of the response is characterized by a switch in morphology to all dichotomous branching. By screening for mutants with altered responses to cold shock, genes responsible for the developmental switch between branch morphologies should be identified.Filamentous fungi play a large role in human affairs. They are major recyclers of biomass and a significant source of losses in agriculture and lumber production as pathogens and agents of spoilage. They affect both producers (loss of product, cost of antifungal actions) and consumers (increased costs, food spoilage, decomposition of wood products) and thus have a significant economic impact. An increase in our understanding of tip growth and branching in fungi would prove useful for more direct control of the growth of the organism. The project should prove useful to batch culturing technologies, control of fungi in material subjected to temperature shifts, and should expand our understanding of the growth of filamentous fungi in the field.