Sexual reproduction and virulence of zygomycete fungi

描述（由申请人提供）：环形毛霉和米根霉是致死性真菌感染毛霉病最常见的病原体，毛霉病是免疫功能低下患者的新发疾病，也是造血恶性肿瘤患者和移植受者中第二常见的真菌感染。然而，与其他真菌病原体相比，对这些物种的毒力知之甚少。本文对两种接合菌种复合物的性发育遗传学和致病性进行了研究。在针对毛霉的研究中，我们将研究三个编码磷酸三糖转运蛋白同源基因、HMG结构域蛋白和RNA解旋酶的基因在三个相关毛霉亚种的合成性位点中的作用。这些基因在性发育过程中的表达模式将被研究。将产生每个基因和等基因菌株的破坏突变体，以测试它们在性发育中的作用。我们最近的研究发现，性别位点可能与圆叶分枝杆菌的孢子大小和毒力有关，其中（-）分离株比（+）分离株产生更大的毒力孢子。我们将在三种宿主模型（培养巨噬细胞、蜡蛾和小鼠）中研究合性位点的基因如何参与孢子大小决定和毒力。同时，在对稻瘟病菌的研究中，我们将建立一个分型系统，将稻瘟病菌和delemar稻瘟病菌作为稻瘟病菌复合体中的两个亚种进行分类。将基于MLST和乳酸脱氢酶基因序列对两个亚种进行高分辨。我们的初步研究表明，在实验室条件下，稻瘟病菌是有性繁殖的，具有腐殖性，而扁豆病菌是不育的，可能毒性更强。我们还将进一步测试这两个亚种的性取向以及蜡蛾和小鼠的毒力，以研究性取向和毒力之间的联系。了解这些病原体的生命周期和详细的系统发育将大大提高我们的知识，以开发新的药物靶点和诊断分型方法，并可能提供控制人类致病性接合菌的手段。

DESCRIPTION (provided by applicant): Mucor circinelloides and Rhizopus oryzae are the most prevalent causal agents of the deadly fungal infection, mucormycosis, which is an emerging disease in immunocompromised patients and the second most common fungal infection in both hematopoietic malignancy patients and transplant recipients. However, considerably less is known about the virulence of these species compared to other fungal pathogens. This study focuses on the genetics of sexual development and pathogenicity of two zygomycete species complexes. In the studies proposed for M. circinelloides, we will investigate the roles of three genes that encode a triose phosphate transporter homolog, HMG domain protein, and RNA helicase in the syntenic sex locus of three related Mucor sub-species. The expression patterns of these genes during sexual development will be investigated. Disruption mutants of each gene and isogenic strains will be generated to test their roles in sexual development. Our recent studies found evidence that the sex locus may be involved in spore size and virulence of M. circinelloides, in which (-) isolates produce more virulent larger spores when compared to (+) isolates. We will investigate how genes in the syntenic sex locus are involved in spore size determination and virulence in three host models: cultured macrophages, the wax moth Galleria mellonella, and the mouse. In parallel, in the studies proposed for R. oryzae, we will establish a typing system to classify R. oryzae and R. delemar that are two sub-species in the R. oryzae complex. The two sub-species will be discriminated at high resolution based on MLST and lactate dehydrogenase gene sequences. Our preliminary studies indicate that R. oryzae is sexual and saprobic, whereas R. delemar is infertile under laboratory conditions and may be more virulent. We will also further test sexuality of the two sub-species as well as virulence in the wax moth and the mouse to investigate links between sexuality and virulence. Understanding the life cycles and detailed phylogeny of these pathogens will greatly enhance our knowledge to develop new drug targets and diagnostic typing approaches, and may provide the means to control human pathogenic zygomycetes. PUBLIC HEALTH RELEVANCE: Mucormycosis is an opportunistic fungal infection recently recognized as emerging cause of infectious disease with a high mortality rate. However, little is known about the relationship of sexual reproduction to pathogenesis in the zygomycetes compared to other fungal pathogens. This project will provide insight to develop novel drug targets, typing methodology to assign species causing infection, and information that can be applied to control zygomycete infections.