Bicoid: A new addition to the body plan of Drosophila

超出提供的空间。尽管双类形态原(BCD)在形成果蝇(DM)胚胎前部的模式中起着关键作用，但在双翅目以外还没有发现床上的同源物。在这里，我们认为保守的驼背(HB)、正齿(OTD)和尾部(Cad)是祖先前花纹系统的关键组成部分，其功能在DM患者中已被床取代。我们将询问在缺乏BCD的情况下，这些基因是否可以在DM中共同作用来控制轴向图案。我们还将研究黄蜂Nasonia vitripenis(NV)的这些基因，其中Hb的突变会产生非常严重的前部表型，这与我们的假设一致，即Hb最初是广泛控制轴向图案所必需的。NV胚胎发生与DM胚胎发生的形态相似性将有助于比较研究。这些对DM和NV的研究将帮助我们理解最近进化的BCD获得调节功能的潜在变化。同时，我们将研究Hb的分子功能，在酵母双杂交筛选中表征它与自身以及与Cad的物理相互作用。目的1我们将继续研究驼背作为一种形态因子，包括它与BCD的协同作用以及它的二聚化能力。由于DM Hb可能已经失去了被Bed取代的功能，我们将从物种的系统发育谱中研究DM中NV Hb的模式特性和Hb基因的模式特性。为了了解NV Hb的调控，将其启动子放置在DM中，以测试其是否受Bed、Hb、OTD或cad控制。利用酵母双杂交筛选，我们观察到了Hb分子之间的分子相互作用。我们将研究这种二聚化的功能，并解决是否需要它作为抑制子的能力，而它的激活需要与BCD(或与OTD？)相互作用。目的2我们将研究OTD作为一种形态发生因子的潜力，并测试在缺乏BCD的情况下，高水平的OTD单独或与Hb联合使用是否能够形成胚胎的前部。我们将克隆NV OTD，并利用RNAi技术研究其表达模式和表型。并研究NV-Hb或BCD、Hb、OTD对其的调节作用。最后，我们将在DM中评估来自不存在BED的物种的OTD蛋白的模式功能。目的3尾部是一种后部形态物质，必须通过BCD的翻译控制或Hb和Cad蛋白之间可能的直接拮抗作用在前部消除。我们将研究Hb和Cad相互作用的遗传学、生物化学和机制，以及这两种机制在无脊椎动物中的相对贡献的演变。我们对两种模式昆虫的比较研究，利用DM分子遗传学的力量，结合NV的独特特征，将使我们能够记录祖先的前额图案系统。我们希望在果蝇身上重建祖先的机制，从衍生的果蝇胚胎进行一次“去进化”，并在昆虫中恢复更一般的发育类型，在那里，床可能看起来不像是协调前模式功能的。表演网站========================================Section End===========================================

EXCEED THE SPACE PROVIDED. Although the Bicoid morphogen (Bcd) plays a pivotal role in patterning the anterior of the Drosophila (Dm) embryo, no bed homologue has been found outside Diptera. Here, we propose that the conserved hunchback (hb), orthodenticle (otd), and caudal (cad) are the key components of an ancestral anterior patterning system whose function has been taken over by bed in Dm. We will ask whether these genes can act together in Dm to control axial patterning in the absence of bcd. We will also study these genes in the wasp Nasonia vitripenis (Nv) where a mutation in hb produces a very severe anterior phenotype, consistent with our hypothesis that hb was originally necessary for extensive control of axial patterning. The morphological similarity of Nv embryogenesis to that of Dm will facilitate comparative studies. These studies in Dm and Nv will help us understand the changes underlying the acquisition of regulatory functions by the recently evolved Bcd. In parallel, we will study the molecular function of Hb, characterizing its physical interactions with itself and with Cad identified in a yeast two-hybrid screen. Aim 1 We will continue our study of Hunchback as a morphogen, including a study of its synergy with Bcd, as well as its ability to dimerize. As Dm hb might have lost functions that have been taken over by bed, we will study in Dm the patterning properties of Nv hb and of hb genes from a phylogenetic spectrum of species. To understand Nv hb regulation, its promoter will be placed in Dm to test whether it is controlled by bed, hb, otd or cad. Using a yeast two- hybrid screen, we have observed a molecular interaction between Hb molecules. We will investigate the function of this dimerization and address whether it is required for the ability of Hb to act as a represser, while its activation requires the interaction with Bcd (or with Otd?). Aim 2 We will study the potential of Otd as a morphogen, and test whether high levels of Otd, alone or in combination with Hb, can pattern the anterior of the embryo in the absence of bcd. We will clone Nv otd, study its expression pattern and phenotype using RNAi. and study its regulation by Nv hb, or by bcd, hb and otd when placed in Din. Finally, we will assess in Dm the patterning function of Otd proteins from species where bed does not exist. Aim 3 caudal is a posterior morphogen that must be eliminated at the anterior, through translational control by Bcd, or by a possible direct antagonism between Hb and Cad proteins. We will study the genetics, biochemistry and mechanisms of the interaction between Hb and Cad as well as the evolution of the relative contribution of the two mechanisms in invertebrates. Our comparative studies in two model insects, using the power of Dm molecular genetics combined with the unique features of Nv, will allow us to document the ancestral anterior patterning system. We hope to reconstruct in Drosophila the ancestral mechanisms, to perform a "de-evolution" from the derived fly embryo and revive the more generic type of development in insects where bed might not have appeared to coordinate anterior patterning functions. PERFORMANCE SITE ========================================Section End===========================================