Characterization and cloning of X. tropicalis Craniofacial Mutants

描述(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需的分子机制知之甚少。在这项提案中，我们将研究一种新兴的模式系统-热带非洲爪哇的颅面发育。在最近的一次正向遗传筛查中，我们发现了两个突变体，JAWS和JAWBAKER，它们在头面部结构的发育过程中表现出特定的胚胎缺陷。这些突变体表现出一种简单的孟德尔遗传模式，提示存在单个隐性突变基因座。在头面部缺陷之外，胚胎的其余部分看起来像野生型。这项建议的目标是描述这两个突变体的特征，并确定在发育过程中颅面图案开始失败的地点和时间。在第二个目标中，我们将尝试识别突变基因座，这将极大地提高我们对分子图案缺陷的理解。由于我们对颅面形态发生的了解仍然很肤浅，因此鉴定这些突变有可能极大地提高我们对颅面发育和畸形的理解。此外，这将是克隆热带按蚊正向遗传筛选中发现的突变体的最早尝试之一。这些目标的成功完成将极大地支持未来在这一新兴模式系统中进行基因筛查。 头部和颈部的出生缺陷是导致婴儿严重疾病的常见原因。然而，我们对这些结构在胚胎发育过程中如何形成的科学理解仍然很肤浅。我们提出了一系列实验来分析两个具有异常下巴结构的青蛙突变体。更好地了解这些青蛙突变体可以作为了解人类头部和颈部出生缺陷的模型。

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.