Browsing by Subject "Sexual development"
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Item Assessing the Roles of Striatin Orthologs in Fungal Morphogenesis, Sexual Development and Pathogenicity(2012-10-19) Wang, Chih-LiStriatin family proteins contain a caveolin binding domain, a coiled-coil motif, a calmodulin binding domain, and a WD-repeat domain. Homologs of striatin protein have been However, our knowledge of the function and the molecular mechanism of fungal striatin homologs is limited. Based on the conserved sequences of functional domains, I hypothesized that the fungal striatin orthologs also act as scaffolding proteins that are functionally conserved among fungal species and involved in multiple types of development in the diverse kingdom Mycota. I used reverse genetic strategies to study the function of the Aspergillus nidulans striatin ortholog (strA) and the Colletotrichum graminicola striatin ortholog (str1). In assays of sexual development, the strA deletion strain (?strA) produces fewer ascospores with smaller cleistothecia, while the str1 deletion strain (?str1) is defective in perithecia development. The ?strA phenotypes indicate that StrA is associated with ascosporogenesis in cleistothecia. Both ?strA and ?str1 are reduced in radial growth and in conidia production. The ?str1 strain is also altered in its spiral growth pattern and morphology of conidia and hyphopodia, but it produces appressoria similar to wild type. The pairing of nitrate non-utilizing mutants demonstrates that Str1 is required for hyphal fusion. In pathogenicity, ?str1 is less virulent in maize anthracnose leaf blight and stalk rot. The phenotypes of ?str1 are complemented by the Fusarium verticillioides striatin ortholog (fsr1), indicating that Fsr1 and Str1 are functionally conserved. Over-expression of StrA reveals its positive role in conidiation and the sexual production. StrA::eGFP localizes mainly to the endoplasmic reticulum. After comparing the results from these two species and other studied fungal species, I suggest that fungal striatins are involved in five types of development including hyphal growth, hyphal fusion, conidiation, sexual development, and virulence, and propose a model of fungal striatin protein interactions to account for these diverse phenotypes.Item Sexual Development and Meiotic Silencing in Neurospora crassa(2014-07-29) Suesc?n Torres, Ana VictoriaMeiotic silencing refers to the mechanism of silencing genes or chromosomes without a homologous counterpart (unpaired) during meiotic prophase I. Meiotic silencing has been described in several eukaryotes, including humans. Failure to complete meiotic silencing may be detrimental to the organism. There is a necessity for understanding the regulation of the process. Neurospora is a powerful model system to study gene silencing phenomena. Numerous genes have been determined to be involved in meiotic silencing in Neurospora; however, very little is known about the molecular mechanisms underlying the process. To understand the regulation of meiotic silencing, it is required to combine different approaches such as genetics, proteomics and biochemical analyses. There is a need for introducing biochemical approaches to the study of meiotic silencing and other processes occurring during sexual development in N. crassa. However, protein extraction from sexual tissue is challenging due to the mechanical difficulties associated with disruption of sexual structure. I standardized a strategy that optimizes protein extraction from sexual tissue. Using this strategy, I studied protein-protein interactions among components of the meiotic silencing machinery and determine the proteome of sexual development. I identified new protein interactions during meiotic silencing in N. crassa, and established protein-binding partners for the suppressor of meiotic silencing SMS-5. These interacting partners, PAF400 and Pianissimo represent new molecular components involved in the nuclear initial stage of the meiotic silencing mechanism. Interactions between SMS-5, PAF400, and Pianissimo may represent the connection between chromatin remodeling, DNA repair, signaling transduction pathways and meiotic silencing. I describe the experiments and data analyses used to develop a comprehensive proteomics data set and a functional catalogue for N. crassa sexual development. I used a global proteomics approach and comparative protein functional analysis to investigate the potential molecular differences between two stages of sexual development in filamentous fungi. The data show that secondary metabolites biosynthesis and cellulase activity are required in fruiting body maturation. N. crassa functional catalogue of sexual development proteins will serve as a reference tool for further studies related to sexual development not only in N. crassa, but also in other filamentous ascomycetes.