Molecular Analysis of Photoregulated Development

丝状真菌中的分生孢子（无性孢子形成）， 构巢曲霉，涉及多细胞的形成， 产生有色的单倍体分生孢子的分化结构 在精确的预定时间。已经证明光是 需要分生孢子，但只会引起发展， 辐射发生在发育的关键时期。 此外，红光可诱导产孢，抑制产孢 通过立即转变为远红光， 观察到的光敏色素介导的反应的特征， 植物几种不同种类的影响光线的突变体 已鉴定出依赖分生孢子。有些突变体会 光敏感，允许分生孢子在没有 光，而其他影响分生孢子的能力， 特定波长。因此，似乎光信号是 在A.通过光敏色素样感光体， 通过未知的机制将信息传递给基因， 控制无性发育。这项建议的目的是 详细了解调节 光介导的分生孢子形成。的主要目的 这项工作是识别和表征红光， 光敏色素的分子克隆 相关序列一个类似光敏色素的克隆已经被分离出来， 实验提出了比较的序列和功能， 助理已知光敏色素基因的nidulans光敏色素基因 从植物。这些实验包括确定DNA 基因组和cDNA克隆的序列，推断出 转录表达，遵循以下模式： 通过使用基因融合的翻译表达， 光敏色素特异性抗体，并检查表型 基因破坏剂这项工作的另一个目的是确定 在光转导途径中发生的相互作用。 在克隆基因（acoD）中分离出了突变体， 对红光敏感。实验提出了检查 acoD的转录和翻译活性， 生长和光照条件，以确定在核苷酸 消除导致红光不敏感的突变缺陷， 并通过分离鉴定基因间的相互作用， 抑制突变的分析。这些研究将有助于 阐明影响细胞的复杂调节机制， 分化是真核生物。

Conidiation (asexual sporulation) in the filamentous fungus, Aspergillus nidulans, involves the formation of multicellular differentiated structures that produce pigmented, haploid conidia at precisely scheduled times. It has been shown that light is necessary for conidiation, but will only elicit development if irradiation occurs during a critical period of development. Furthermore, conidiation is induced by red light and suppressed by an immediate shift to far red light, a property that is characteristic of phytochrome mediated responses observed in plants. Several different classes of mutants that affect light dependent conidiation have been identified. Some mutants abolish light sensitivity, allowing conidiation to occur in the absence of light, while others affect the ability to conidiate at specific wavelengths. Thus, it appears that light signals are perceived in A. nidulans by a phytochrome like photoreceptor that transmits information by an unknown mechanism to genes that control asexual development. The objective of this proposal is to develop a detailed understanding of the mechanisms that regulate light mediated conidiation in this organism. The major aim of this work is to identify and characterize the red light photoreceptor through the molecular cloning of phytochrome related sequences. A phytochrome like clone has been isolated and experiments are proposed to compare the sequences and function of the A. nidulans phytochrome gene with known phytochrome genes from plants. These experiments include determining the DNA sequence of both genomic and cDNA clones, deducing the pattern of transcriptional expression, following the pattern of translational expression through the use of gene fusions and phytochrome specific antibodies, and examining the phenotype of gene disruptants. Another aim of this work is to identify interactions that occur within the photo transduction pathway. Mutants have been isolated in a cloned gene (acoD) that affect sensitivity to red light. Experiments are proposed to examine the transcriptional and translational activity of acoD in different growth and illumination conditions, to identify at the nucleotide level the mutational defects that cause red light insensitivity, and to identify gene interactions through the isolation and analysis of suppressor mutations. These studies will help elucidate the complex regulatory mechanisms that affect cellular differentiation is this eukaryote.