Genetic and Molecular Dissection of Hyphal Anastomosis

科学价值。丝状真菌是环境中植物细胞壁物质的主要降解者。有些物种与植物物种的根部存在共生关系，使植物能够从土壤中获得微量营养素。其他真菌种类是植物或动物/人类的致病因子。丝状真菌既是有益的，也是致病的，它们通过顶端延伸、分枝和菌丝融合生长，形成相互连接的菌丝网络。这种菌丝网络被认为对于根伴生真菌和腐生真菌在整个生态系统中的营养转移以及病原真菌中菌落的建立和资源的开发是必不可少的。对丝状真菌粗糙脉孢霉的研究揭示了一个复杂的、受严格调控的萌发/菌丝融合的生物学过程。在细胞融合前的趋化相互作用中，已发表的研究表明，信号蛋白从一个融合细胞末端到其伴侣的交替振荡为遗传相同的细胞之间的信号传递提供了一个引人注目的模型。生理差异发生在很短的时间内，并与信号转导反馈机制有关。从这些研究中可以明显看出，粗毛拟青霉使用一种分泌的化学语言来协调趋化作用和细胞融合。这个项目的第一个目标是阐明丝状真菌用来协调其菌丝网络发展的信号机制和语言。细胞融合是交配和组织形成(即多核肌肉细胞和破骨细胞的形成)过程中的一个重要发育过程，尽管与细胞-细胞融合相关的机制尚未得到很好的描述。这项工作的第二个目标是确定细胞壁分解/膜合并(梭菌)所需的额外成分。这项工作的最终目标是了解菌丝网络的形成如何允许真菌个体执行在自然界中竞争所需的生理和发育过程，并完成其生命周期。更广泛的影响。丝状真菌中的菌丝融合类似于基因相同的细胞之间的细胞融合，导致合胞体，如肌肉分化期间的成肌细胞融合，胎盘发育期间的滋养细胞融合，以及骨形成过程中破骨细胞之间的融合。因此，研究粗毛藻中的细胞-细胞融合为理解更复杂的真核生物中细胞融合事件的分子机制提供了有用的模型。这个项目是一个很好的培训项目，因为它结合了活细胞成像技术和显微镜，以及遗传学、生物化学、基因组学和分子生物学。预计本科生研究人员将成为研究论文的共同作者，就像之前的NSF奖项一样。关于萌发/菌丝融合的细胞生物学工作将继续与对流体动力学感兴趣的数学家、生物纳米技术专家和业余真菌学家合作。目前正在与法国纪录片工作者合作制作一部法国电视纪录片，其重点是丝状真菌菌丝网络的分析和功能。

Scientific merit. Filamentous fungi are the primary degraders of plant cell wall material in the environment. Some species are associated with the roots of plant species in a symbiotic relationship that allows plants to gain micronutrients from soil. Other fungal species are disease-causing agents in plants or animal/humans. Filamentous fungi, both beneficial and pathogenic species, grow by tip extension, branching and hyphal fusion to form an interconnected hyphal network. This hyphal network is believed to be essential for transfer of nutrients throughout ecosystems by root associated and saprophytic fungi and for colony establishment and exploitation of resources in pathogenic fungi. Studies on the filamentous fungus, Neurospora crassa, have revealed a complex and carefully regulated biological process of germling/hyphal fusion. During chemotropic interactions prior to cell fusion, published studies have shown that the alternating oscillation of signaling proteins from the tip of one fusion cell to its partner provides a compelling model for signaling between genetically identical cells. Physiological differences occur over a short time period and are associated with signal transduction feedback mechanisms. From these studies, it is evident that N. crassa uses a secreted chemical language to coordinate chemotropic interactions and cell fusion. The first objective of this project is to elucidate the signaling mechanisms and the language that filamentous fungi use to coordinate development of their hyphal network. Cell fusion is an important developmental process during mating and during tissue formation (i.e. the formation of multinucleate muscle cells and osteoclasts), although the mechanisms associated with cell-cell fusion are not well characterized. A second objective of this work is to identify additional components necessary for cell wall disassembly/membrane merger (fusogens). The ultimate goal of this work is to understand how the formation of the hyphal network allows a fungal individual to perform the physiological and developmental processes required to compete in nature and to complete its life cycle. Broader impact. Hyphal fusion in filamentous fungi is comparable to cell fusion events between genetically identical cells resulting in syncytia, such as myoblast fusion during muscle differentiation, trophoblast fusion during placental development and between osteoclasts during bone formation. Thus, studying cell-cell fusion in N. crassa provides a useful model for understanding molecular mechanisms of cell fusion events in more complex eukaryotic species. This project is an excellent training project as it incorporates live cell imaging techniques and microscopy, as well as genetics, biochemistry, genomics and molecular biology. It is expected that undergraduate researchers will be co-authors on research papers, as for previous NSF awards. The cell biological work on germling/hyphal fusion will continue collaborations with a mathematician interested in fluid dynamics, a bio-nanotechnologist, and amateur mycologists. A French television documentary that focuses on the analysis and function of a filamentous fungal hyphal network is currently being developed in collaboration with French documentarians.