Research

Molecular Genetics of Filamentous Fungi

Cell specialization, cell communication and nonself recognition are crucial mechanisms in microbial organisms such as filamentous fungi. In filamentous fungi, growth occurs by hyphal tip extension, branching and repeated fusion of hyphae, ultimately forming an exquisitely connected network, from which the individual colony grows and reproduces. My research interests are focused on understanding communication and signaling mechanisms that mediate the hyphal fusion process and nonself recognition mechanisms that occur before and after hyphal fusion. The experimental tractability and availability of a large number of mutants in the filamentous fungus, Neurospora crassa, makes it a superb system to delineate both fungal-specific and general mechanisms of cell communication and nonself recognition. We use a combination of molecular biology, genetics, cell biology, genomics and bioinformatics to investigate the molecular and cellular basis of nonself recognition during both sexual and asexual phases of growth in filamentous fungi.

Nonself Recognition and Programmed Cell Death

Self/nonself discrimination is a ubiquitous and essential function of both multicellular and microbial species, and is an aspect of biology that has long fascinated scientists. Nonself recognition in filamentous fungi is mediated by differences at het (for heterokaryon incompatibility) loci. Hyphal fusion between two individuals that have genetic differences at het loci triggers programmed cell death (PCD)of the fusion cell. Nonself recognition and PCD functions to prevent transfer of mycoviruses and senescence plasmids between fungal individuals within a population. Our current research objectives include elucidating the molecular mechanism of nonself recognition, understanding how nonself recognition triggers fungal PCD and investigations into the evolution of nonself recognition systems in fungi.

Germling and hyphal fusion

The ability to form a hyphal network is a hallmark of filamentous fungi. In filamentous ascomycete species such as Neurospora crassa, an individual hypha (a multinucleate, multicellular filament with incomplete crosswalls, or septa) grows by hyphal tip extension and branching. Behind the growing colony margin, fusions between hyphae are continuously formed (a process called anastomosis), yielding a network of interconnected hyphae, or mycelium, that makes up the fungal individual. Although the capacity to form a hyphal network is ubiquitous in filamentous fungi, little is known about the mechanism or function of an interconnected hyphal network. We have characterized a number of hyphal and germling fusion mutants in N. crassa, including strains with lesions in genes encoding MAP kinase signal transduction components and a number of transcription factors. Our current research objectives include determining the molecular mechanism of self-signling and the nature of the signaling molecules, the relationship of the signal transduction pathway to the fungal cytoskeleton and identifying target genes of transcription factors which are required for the germling and fusion process.

Plant cell wall deconstruction by Neurospora crassa

In nature, filamentous fungi are the primary degraders of plant biomass. Plant biomass is a potential source for the production of biofuels. Neurospora crassa is an efficient degrader of plant cellulose and hemicellulose and is found in nature primarily on grasses. In a project funded by the Energy Biosciences Institute, we are using the genomic and genetic tools available with N. crassa to decipher transcriptional, secretory and enzymatic regulatory mechanisms associated with plant cell wall deconstruction. These efforts have the potential to provide tools and components that can be used to optimize plant biomass utilization for the production of biofuels.

Recent Publications

Simonin A, Palma-Guerrero J, Fricker M, Glass NL, 2012. The physiological significance of network organization in fungi. Eukaryot Cell (in press).

Hutchison EA, Bueche JA, Glass NL, 2012. Diversification of a protein kinase cascade: IME-2 is involved in nonself recognition and programmed cell death in Neurospora crassa. Genetics (in press).

Coradetti ST, Craig JP, Xiong Y, Shock T, Tian C,  Glass, NL, 2012.  Conserved and essential transcription factors for cellulase gene expression in ascomycete fungi. Proc Natl Acad Sci USA 109:7397-7402.

Znameroski EA, Coradetti ST, Roche CM, Tsai JC, Iavarone AT, Cate JHD, Glass NL, 2012. Induction of lignocellulose degrading enzymes in Neurospora crassa by cellodextrins. Proc Natl Acad Sci USA 109:6012-6017.

Richards, F., N. L. Glass and A. Pringle. Cooperation among germinating spores facilitates the growth of the fungus Neurospora crassa. Biol Letts (in press). 

Sun J, Tian C, Diamond S, Glass NL, 2012.  Deciphering regulatory mechanisms associated with hemicellulose degradation in Neurospora crassa. Eukaryot Cell 11:482-493.

Schmoll M, Tian C, Sun J, Tisch D, Glass NL, 2012. Unraveling the molecular basis of light-modulated cellulase gene expression-the role of photoreceptors in Neurospora crassa.  BMC Genomics 13:127. 

Roper M, Ellison C, Taylor JW, Glass NL, 2011. Nuclear and genome dynamics in multinucleate ascomycete fungi. Curr Biol 21:R786-93. 

Fernandes AS, Gonçalves AP, Castro A, Lopes TA, Gardner R, Glass NL, Videira A, 2011. Modulation of fungal sensitivity to staurosporine by targeting proteins identified by transcriptional profiling. Fungal Genet Biol 48:1130-1138.

Leeder AC, Palma-Guerrero J, Glass NL, 2011. The Social Network: Deciphering Fungal Language. Nature Rev Microbiol 9:440-451.

Sun J, Glass NL, 2011. Identification of the CRE-1 cellulolytic regulon in Neurospora crassa. PLoS One  6:e25654. 

Gilbert LB, Kasuga T, Glass NL, Taylor JW, 2011. Array CGH Phylogeny: How accurate are comparative genomic hybridization-based trees? BMC Genomics 12:487. 

Ellison CE, Hall C, Kowbel D, Welch J, Brem RB, Glass NL, Taylor JW, 2011. Population genomics and local adaptation in wild isolates of a model microbial eukaryote. Proc Natl Acad Sci USA 108:2831-2836. 

Tian C, Li J, Glass NL, 2011. Exploring the bZIP transcription factor regulatory network in Neurospora crassa. Microbiol 157:747-759. 

Ha SK, Galazka JM, Kim SR, Choi JH, Yang X, Seo JH, Glass NL, Cate JHD, Jin YS, 2011. Engineered Saccharomyces cerevisiae capable of simultaneous cellobiose and xylose fermentation. Proc Natl Acad Sci USA 108:504-509.

Hall C, Welch J, Kowbel DJ, Glass NL, 2010. Evolution and diversity of a fungal self/nonself recognition locus. PLoS One 5:e14055. 

Galazka JM, Tian C, Beeson WT, Martinez B, Glass NL, Cate JHD, 2010. Cellodextrin transport in yeast for improved biofuel production. Science 330:84-86.

Li S, Du J, Sun J, Galezka JM, Glass NL, Cate JHD, Zhao H, 2010. Overcoming glucose repression in mixed sugar fermentation by co-expressing a cellobiose transporter and a ß-glucosidase in Saccharomyces cerevisiae. Molec BioSystems 6:2129-2132.

Sun J, Phillips CM, Anderson CT, Beeson WT, Marletta MA, Glass NL, 2011. Expression and characterization of Neurospora crassa endoglucanase GH5-1. Protein Expr Purif 75:147-154.

Greenwald CJ, Kasuga T, Glass NL, Shaw BD, Ebbole DJ, Wilkinson HH, 2010. Temporal and spatial regulation of gene expression during asexual development of Neurospora crassa. Genetics 186:1217-1230. 

Simonin A, Rasmussen CG, Yang M, Glass NL, 2010. Genes encoding a striatin-like protein (ham-3) and a forkhead associated protein (ham-4) are required for hyphal fusion in Neurospora crassa. Fungal Genet Biol 47:855-868.

Hutchison EA, Glass NL, 2010. Meiotic regulators Ndt80 and Ime2 have different roles in Saccharomyces and Neurospora. Genetics 185:1271-1282.

Castro A, Lemos C, Falcão A, Fernandes AS, Glass NL, Videira A, 2010. Rotenone enhances the antifungal properties of staurosporine. Eukaryot Cell 9:906-14.

Aanen, D.K., A.J.M. Debets, N. L.Glass and S.J. Saupe, 2010. Biology and genetics of vegetative incompatibility in fungi. In Cellular and Molecular Biology of Filamentous Fungi. K.A . Borkovich and D. Ebbole, Eds. American Society of Microbiology, pp. 274-288.

Read, N. D., A. Fleißner, M. G. Roca and N. L. Glass, 2010. Hyphal Fusion. In Cellular and Molecular Biology of Filamentous Fungi. K.A. Borkovich and D. Ebbole, Eds. American Society of Microbiology, pp. 260-273.

Tian, C., W.T. Beeson, A.T. Iavorone, J. Sun, M.A. Marletta, J,H. Cate and N.L. Glass, 2009. Systems analysis of plant cell wall degradation by the model filamentous fungus, Neurospora crassa. Proc Natl Acad Sci USA 106:22157-22162.

Fleissner, A., A.C. Leeder, M.G. Roca, N.D. Read and N.L. Glass, 2009. Oscillatory recruitment of signaling proteins to cell tips promotes coordinated behavior during cell fusion. Proc Natl Acad Sci USA 106:19387-19392.

Hutchison, E., S. Brown, C. Tian and N.L. Glass, 2009. Transcriptional profiling and functional analysis of heterokaryon incompatibility in Neurospora crassa reveals that reactive oxygen species, but not metacaspases, are associated with programmed cell death. Microbiol 155:3957-3970.

Videira, A,. T. Kasuga, C. Tian, C. Lemos, A. Castro and N. L. Glass, 2009. Transcriptional analysis of the Neurospora crassa response to phytospingosine reveals links to mitochondrial function. Microbiol 155:3134-3141.

Kasuga, T., G. Mannhaupt and N. L. Glass, 2009. Relationship between phylogenetic distribution and genomic features in Neurospora crassa. PLoS One 4:e5286.

Fleissner, A., S. Diamond and N. L Glass, 2009. The Saccharomyces cerevisiae PRM1 homolog in Neurospora crassa is involved in vegetative and sexual cell fusion events, but also has post-fertilization functions. Genetics 181:497-510 .

Fleissner, A., A. R. Simonin and N. L. Glass, 2008. Cell fusion in the filamentous fungus, Neurospora crassa. Methods Mol Biol 475:21-38.

Kasuga, T. and N. L Glass, 2008. Dissecting colony development of Neurospora crassa using mRNA profiling and comparative genomics approaches. Eukaryot Cell 7:1549-1564.

Castro, A., C. Lemos, A. Falcão, N. L. Glass and A. Videira, 2008. Increased resistance to complex I mutants to phytosphingosine-induced programmed cell death. J Biol Chem 283:19314-19321.

Rasmussen, C. G., R. M. Morgenstein, S. Peck and N. L. Glass, 2008. Lack of the GTPase RHO-4 in Neurospora crassa causes a reduction in numbers and aberrant stabilization of microtubules at hyphal tips. Fungal Genet Biol 45:1027-1039.

Wichmann G., J. Sun, K. Dementhon, N.L. Glass and S. E. Lindow, 2008. A novel gene, phcA from Pseudomonas syringae induces programmed cell death in the filamentous fungus Neurospora crassa. Mol Microbiol 68:672-689

Rasmussen, C. G. and N. L. Glass, 2007. Localization of RHO-4 indicates differential regulation of conidial versus vegetative septation in the filamentous fungus Neurospora crassa. Eukaryot Cell 6:1097-107

Dunlap, J.C., K.A. Borkovich, M.R. Henn, G.E. Turner, M.S. Sachs, N.L. Glass, K. McClusky, M. Plamann, J.E. Galagan, B.W. Birren et al., 2007. Enabling a community to dissect an organism—Overview of The Neurospora Functional Genomics Project. Adv Genetics 57:49-96.

Tian, C., T. Kasuga, M. S. Sachs and N. L. Glass, 2007. Transcriptional profiling of cross pathway control in Neurospora crassa: Comparative analysis of the Gcn4 and CPC1 regulons. Eukaryot Cell 6:1018-29.

Fleissner, A. and N. L. Glass, 2007. SO, a protein involved in hyphal fusion in Neurospora crassa, localizes to septal plugs. Eukaryot Cell 6:84-94.

Dementhon, K., G. Iyer and N. L. Glass, 2006. VIB-1 is required for expression of genes necessary for PCD in Neurospora. Eukaryot Cell 5:2161-2173.

Glass, N. L. and K. Dementhon, 2006. Nonself recognition and programmed cell death in filamentous fungi. Curr Opin Microbiol 9:553-558.

Kaneko, I., K. Dementhon, Q. Xiang and N. L. Glass, 2006. Non-allelic interactions between het-c and a polymorphic locus, pin-c, are essential for nonself recognition and programmed cell death in Neurospora crassa. Genetics 172:1545-55.

Kasuga, T., J.P. Townsend, C. Tian, L.B. Gilbert, G. Mannhaupt, J.W. Taylor and N.L. Glass, 2005. Long-oligomer microarray profiling in Neurospora crassa reveals the transcriptional program underlying biochemical and physiological events of conidial germination. Nucleic Acids Res 33:6469-85.

Rasmussen, C. G. and N. L. Glass, 2005. A rho-type GTPase, rho-4, is required for septation in Neurospora crassa. Eukaryot Cell 4:1913-1925.

Fleißner, A., S. Sarkar, D. J. Jacobson, M. G. Roca, N. D. Read and N. L. Glass, 2005. Identification and characterization of so, a hyphal fusion mutant of Neurospora crassa. Eukaryot Cell 4:920-30.

Xiang, Q. and N. L. Glass, 2004. The control of mating type heterokaryon incompatibility by vib-1, a locus involved in het-c incompatibility in Neurospora crassa. Fungal Genet Biol 41:1063-1076.

Pandey, A. M. G. Roca, N. D. Read and N. L. Glass, 2004. Role of a mitogen-activated kinase in hyphal fusion and conidial germination in Neurospora crassa. Eukaryot Cell 3:348-58.

Glass, N.L., C. Rasmussen, M.G. Roca and N.D. Read. 2004 Hyphal homing, fusion and mycelial interconnectedness. Trends Microbiol 12:135-41.

 

Honors and Awards

• Miller Professorship - 2012
• Fellow - American Academy of Microbiology, American Society for Microbiology - 2010
• Fellow - American Association for the Advancement of Science - 2005