Molecular Analysis of Fungal Sporulation

丝状子囊菌的分生孢子(无性孢子)的形成涉及由几种不同组织类型组成的分化结构的产生，并导致大量新的Poly(A)+RNA的合成，这些新的Poly(A)+RNA是未分化的菌丝体中没有观察到的。这种生物的一个重要特征是，分生孢子在深层培养中通常被抑制，但可以通过将生长环境改变为空气界面来启动。然而，只有当生物体达到一种称为发育能力的状态变化时，诱导(菌落从液体到固体的转移)才能启动分生孢子形成。这项拟议的研究旨在确定发育能力的分子基础，并了解调控途径的启动机制。预诱导突变体的遗传学特征已经确定，但需要一种分子方法来确定不同的预诱导功能如何相互作用，并推断预诱导基因的表达如何启动大量诱导后基因的表达，这些基因在诱导状态下的生长在转录上被激活。这一建议的具体目的是(L)克隆以诱导前和诱导后早期突变为代表的野生型基因；(2)比较这些基因的转录活性与通过温度漂移分析确定的表达时间；以及(3)通过确定一个基因的转录是否受到另一个基因的突变的影响来确定基因的相互作用。发育，即一个全能的未分化细胞向一组受调控的分化细胞的转变，是一个复杂的过程。使用“简单的”真核生物，如曲霉，作为分化过程中使用的机制的模型系统，可以为理解更复杂的生物体的分化过程提供方法和机制。从这项工作中获得的结果应该会让我们更深入地了解至今仍是神秘的分化过程。

The formation of conidia (asexual spores) in the filamentous ascomycete, Aspergillus nidulans, involves the production of differentiated structures composed of several different tissue types and results in the synthesis of a large number of new poly (A)+ RNAs not observed in undifferentiated mycelia. An important feature of this organism is that conidiation is normally suppressed in submerged culture, but can be initiated by changing the growth habitat to an air interface. Induction (the transfer of colonies from liquid to solid media), however, will permit the initiation of conidiation only after the organism has attained a change of state termed developmental competence. The proposed research is directed toward determining the molecular basis of developmental competence and toward understanding the mechanisms involved in the initiation of a regulatory pathway. Preinduction mutants have been genetically characterized, but a molecular approach is required to determine how different preinduction functions interact, and to deduce how the expression of preinduction genes initiates the expression of the large number of post induction genes which are transcriptionally activated by growth in the induced state. The specific aims of this proposal are (l) to clone the wild-type genes represented by the preinduction and early postinduction mutants, (2) to compare the transcriptional activity of these genes with their time of expression as ascertained by temperature-shift analysis, and (3) to identify gene interactions by determining if the transcription of one gene is affected by the mutation of another gene. Development, the transition of a totipotent undifferentiated cell to a regulated collection of differentiated cells, is a complex process. The use of a "simple" eukaryotic organism such as Aspergillus as a model system for mechanisms utilized in the differentiation process can suggest approaches and mechanisms for understanding the process in more complex organisms. The results to be obtained from this work should give greater insight into the as yet mysterious process of differentiation.