Characterization and cloning of X. tropicalis Craniofacial Mutants

描述（由申请人提供）：颅面畸形是儿童最常见的出生缺陷之一，并导致这些婴儿的大量发病率和死亡率。尽管这种疾病很严重，但人们对正确形成面部结构所必需的分子机制知之甚少。在这个提议中，我们将研究一个新兴的模式系统，热带非洲爪蟾颅面发育。在最近的前向基因筛选中，我们发现了两个突变体，颌骨和颌骨，在颅面结构的发育中表现出特定的胚胎缺陷。这些突变体表现出一个简单的孟德尔遗传模式，暗示了一个单隐性突变位点。除了颅面缺损外，胚胎的其余部分呈野生型。本提案的目标是表征这两个突变体，并确定在发育过程中颅面模式开始失败的位置和时间。在第二个目标中，我们将尝试确定突变位点，这将大大提高我们对分子模式缺陷的理解。由于我们对颅面形态发生的理解仍然很肤浅，表征这些突变体有可能大大提高我们对颅面发育和畸形的理解。此外，这将是首次尝试克隆热带棘球绦虫在正向遗传筛选中发现的突变体之一。这些目标的成功完成将极大地支持未来在这一新兴模型系统中的遗传筛选。

DESCRIPTION (provided by applicant): Craniofacial malformations are among the most common birth defects in children and lead to substantial morbidity and mortality for these infants. Despite the severity of the illness, little is known about the molecular mechanisms that are necessary for correct formation of facial structures. In this proposal, we will investigate craniofacial development in an emerging model system, Xenopus tropicalis. During a recent forward genetic screen, we identified two mutants, jaws and jawbreaker, that exhibit a specific embryonic defect in the development of craniofacial structures. These mutants show a simple Mendelian inheritance pattern suggestive of a single recessive mutant locus. Outside of the craniofacial defect, the remainder of the embryo appears wildtype. It is the goal of this proposal to characterize these two mutants and identify where and when during development craniofacial patterning begins to fail. In a second aim, we will attempt to identify the mutant locus which will greatly improve our understanding of the molecular patterning defect. Because our understanding of craniofacial morphogenesis remains superficial, characterizing these mutants has the potential of substantially improving our understanding of craniofacial development and malformations. In addition, this will represent one of the very first attempts to clone a mutant identified in a forward genetic screen in X. tropicalis. Successful completion of these goals will greatly support future genetic screens in this emerging model system. Birth defects of the head and neck are a common cause of serious illness in infants. Yet, our scientific understanding of how these structures form during embryonic development remains superficial. We propose a series of experiments to analyze two frog mutants that have abnormal jaw structure. A better understanding of these frog mutants can then be used as a model to understand birth defects of the head and neck in humans.