Endocrine Regulation of the Ecdysteroid Cascade During Insect Metamorphosis

9817339里迪福德变形包括一个壮观的变化形式，如转变的毛毛虫变成一个可爱的蝴蝶。 Riddiford博士试图了解激素调节这一系列复杂事件的细胞和分子基础，这些事件是这种转变在正确的时间以协调的方式发生所必需的。 在昆虫中，幼虫的生长需要其表皮外骨骼的周期性蜕皮，这是由作用于表皮的类固醇激素蜕皮激素启动和协调的，蜕皮激素在第二种激素保幼激素的存在下形成角质层。 当蜕皮激素在不存在保幼激素的情况下起作用时，发生变态，引起表皮的变化，导致新型角质层和成虫（成虫）盘和处理器细胞分化以形成新的成虫结构。 Riddiford博士将利用蜕皮激素受体及其伴侣ultraspiracle和早期蜕皮激素诱导的转录因子的同种型的抗体，必要时，RNA的原位杂交分析，研究在幼虫蜕皮期间保幼激素存在下表皮细胞对循环蜕皮激素的反应差异，以及在烟草天蛾（Manduca sexta）变态期间不存在保幼激素。 这些反应将被比较，主要是在幼虫的生活中增殖的成虫细胞，然后成为致力于变态早期在最后的幼虫阶段，以阐明这两种不同类型的细胞响应相同的激素环境的机制。 Riddiford博士还将开发一种方法，当表皮在体外和动物体内对蜕皮激素产生反应时，选择性地删除表皮中的蜕皮激素受体或诱导的转录因子之一，以测定这些不同因子在蜕皮期间引起新角质层形成和变态所需的细胞开关中的功能作用。 这些研究将提供更深入的了解如何两个主要的蜕皮激素，蜕皮激素和20-羟基蜕皮激素，启动和协调细胞的反应，在蜕皮期间和表皮细胞的命运，这是变态的标志和保幼激素如何指导蜕皮激素的行动，以防止变态。 获得的基本知识也可能导致新的选择性方法来控制昆虫。

9817339RiddifordMetamorphosis involves a spectacular change of form such as the transformation of a caterpillar into a lovely butterfly. Dr. Riddiford seeks to understand the cellular and molecular basis of the hormonal regulation of the complex series of events necessary for this transformation to occur in a coordinated manner at the right time. In insects the growth of the larva requires periodic molts of its cuticular exoskeleton which are initiated and coordinated by the steroid hormone ecdysone acting on the epidermis which makes the culticle in the presence of a second hormone juvenile hormone. Metamorphosis occurs when ecdysone acts in the absence of juvenile hormone, causing changes in the epidermis that lead to a new type of cuticle and the differentiation of imaginal (adult) discs and processor cells to form new adult structures. Dr. Riddiford will utilize antibodies to the isoforms of the ecdysone receptor and its partner ultraspiracle and of the early ecdysteroid-induced transcription factors and when necessary, in situ hybridization analysis of the RNAs, to study differences in epidermal cell response to the circulating ecdysteroids in the presence of juvenile hormone during a larval molt and in its absence during metamorphosis of the tobacco hornworm, Manduca sexta. These responses will be compared to those in the imaginal cells which mainly proliferate during larval life, then become committed for metamorphosis early in the final larval stage to elucidate the mechanism whereby these two different types of cells respond to the same hormonal milieu. Dr. Riddiford will also develop a method of selectively deleting one of the ecdysone receptors or the induced transcription factors in the epidermis when it is responding to ecdysteroid in vitro and then in the animal so as to assay the functional roles of these various factors in causing both new cuticle formation during the molts and the cellular switches necessary for metamorphosis. These studies will provide deeper insight into how the two major ecdysteroids, ecdysone and 20-hydroxyecdysone, initiate and coordinate the cellular responses during a molt and during the switching of the epidermal cell fate that is the hallmark of metamorphosis and how juvenile hormone directs ecdysteroid action to prevent metamorphosis. The basic knowledge gained also may lead to new selective approaches to insect control.