Molecular and Genetic Dissection of Hyphal Anastomosis

丝状真菌通过顶端延伸、分支和菌丝融合来生长，以形成构成真菌个体的菌丝网络。 虽然在丝状真菌中已经广泛地研究了顶端生长和分支，但基本上对菌丝融合的机制或菌丝网络形成的功能一无所知。 本实验室在丝状真菌粗糙脉孢菌中使用活细胞成像和共聚焦显微镜对菌丝融合过程进行的研究揭示了一个复杂且仔细调节的生物过程，对真菌个体具有明显的后果。 菌丝融合是增加菌丝细胞质流动和相互连接的一种方式，这在影响菌丝格局形成和发育过程的菌丝内通讯中可能是重要的。 丝状真菌中的菌丝融合与其他生物中的细胞融合事件相当，例如卵子和精子之间的受精事件以及导致合胞体的体细胞融合事件，例如肌肉分化期间的成肌细胞融合。菌丝融合过程必须小心地调节，因为不适当的细胞壁破裂会导致菌丝的溶解。 N. crassa是评估丝状真菌中菌丝融合过程和功能的最佳丝状真菌，因为其易于活细胞成像技术（http：//www.neurospora.com/）、全基因组序列信息（http：//www-genome.wi.mit.edu/annotation/fungi/neurospora/）、菌丝融合突变体的可用性以及遗传和分子技术的简易性。 初步结果表明，菌丝融合需要一系列的信号事件，其中之一是由地图激酶途径介导的。 菌丝融合突变体表现出生理和发育缺陷，表明未能形成菌丝网络具有生理后果。 本项目的目标是通过共聚焦显微镜活细胞成像，遗传和生化分析的组合，以阐明自我信号，极化和膜融合的机制来表征菌丝融合突变体。 最终目标是了解菌丝网络的形成如何允许真菌个体执行完成其生命周期所需的生理和发育过程。 了解丝状真菌中的菌丝融合过程不仅将揭示菌丝网络形成的功能，而且将为其他真核生物中的细胞融合事件提供模型。

Filamentous fungi grow by tip extension, branching and hyphal fusion to form a hyphal network that makes up a fungal individual. Although tip growth and branching have been extensively studied in filamentous fungi, essentially nothing is known about the mechanism of hyphal fusion or the function of the formation of a hyphal network. Studies by this laboratory on the hyphal fusion process using live cell imaging and confocal microscopy in the filamentous fungus, Neurospora crassa, have revealed a complex and carefully regulated biological process with obvious consequences to the fungal individual. Hyphal fusion is a way to increase cytoplasmic flow and interconnectedness of hyphae, which may be important in intra-hyphal communication that influences hyphal pattern formation and developmental processes. Hyphal fusion in filamentous fungi is comparable to cell fusion events in other organisms, such as fertilization events between egg and sperm and somatic cell fusion events that result in syncytia, such as myoblast fusion during muscle differentiation. The hyphal fusion process must be carefully regulated because inappropriate cell wall breakdown would result in lysis of the hyphae. N. crassa is the best filamentous fungus to assess the process and function of hyphal fusion in filamentous fungi because of its tractability for live cell imaging techniques (http://www.neurospora.com/), full genome sequence information (http://www-genome.wi.mit.edu/annotation/fungi/neurospora/), the availability of hyphal fusion mutants, and the ease of genetic and molecular techniques. Preliminary results indicate that a series of signaling events are required for hyphal fusion, one of which is mediated by a map kinase pathway. Hyphal fusion mutants show physiological and developmental defects, suggesting that the failure to form a hyphal network has physiological consequences. The objectives of this project are to characterize hyphal fusion mutants using a combination of live cell imaging via confocal microscopy, and genetic and biochemical analysis to elucidate the mechanism of self-signaling, polarization and membrane fusion. The ultimate goal is to understand how the formation of the hyphal network allows a fungal individual to perform the physiological and developmental processes required to complete its life cycle. Understanding the hyphal fusion process in filamentous fungi will not only reveal the function of the formation of the hyphal network, but will provide a model for cell fusion events in other eukaryotic organisms.