The Evolution of Cranial Neural Crest in Mammals: The Genetic Origins of Heterochronic Change

有袋哺乳动物和胎盘哺乳动物的区别在于它们的生殖和生活史策略。所有有袋类动物在出生时都是高度畸形的，但必须拥有足够的功能独立性才能在这种极端状态下发挥作用。以前的工作表明，与其他哺乳动物相比，有袋类动物的脑神经脊相对于神经或中胚层组织分化得更早。这很有趣，因为正确的头面部模式取决于这些组织之间一系列错综复杂的关系。目前的建议将研究神经板分化的遗传分化与神经脊分化和迁移之间的关系。具体目标：当前建议的具体目标是：1)检验假设，即必须分离第一弓顶的亚群，以便在第一弓中建立适当的肌肉-骨骼模式。2)通过建立FGF8和Hoxa2在神经板的表达之间的关系，并将神经脊细胞迁移到ACCH1和2中，研究峡部作为组织中心在中脑/后脑交界处的可能作用。3)检验KROX 20表达所显示的R3和R5的遗传分化是抑制这些区域神经脊迁移的必要成分的假说。智力价值：这项研究将有助于理解脊椎动物头面部纹路的一些具体机制，特别是神经脊在这种纹路中的作用。此外，该项目是关于发展变化产生进化变化的方式的长期研究的一部分。最后，这项研究探讨了发展变化的限制和可能性，并有助于揭示发展机制可能演变的方式。广泛的影响：最重要的是教育。之前的助学金资助了14名本科生的工作。其中两人得到了REU补充剂的支持，其中包括一名非洲裔妇女和一名拉丁美洲裔妇女。这些学生中有13名是女性。通过提供研究经验来教育本科生(特别是代表不足的群体)一直是一种终生的模式，而NSF的支持将使史密斯实验室继续为科学教育做出贡献。此外，在过去10年的NSF资助期间，世界上最大的有袋类胚胎收集之一已经积累起来。在过去的两年里，这些藏品被来自芬兰、德国、巴西和美国的个人使用。进一步的资金将支持这一收藏。。

0316353SmithMarsupial and placental mammals are distinguished by their reproductive and life history strategies. All marsupials are highly altricial at birth, but must possess sufficient functional independence to function at this altricial state. Previous work has shown that when compared to other mammals, the cranial neural crest differentiates early relative to the neural or mesodermal tissues in marsupials. This is of interest as proper craniofacial patterning depends on a series of intricate relations between these tissues. The current proposal will examine the relation between genetic differentiation of the neural plate differentiation and neural crest differentiation and migration. Specific aims: The specific aims of the current proposal are: 1) To test hypotheses that subpopulations of first arch crest, must be segregated in order to establish proper muscular-skeletal patterning in the first arch. 2) To examine the possible role of the isthmus as an organizing center in at the midbrain/hindbrain boundary, by establishing the relation between FGF8 expression, and Hoxa2 expression in the neural plate and migrating neural crest cells into aches 1 and 2. 3) To test the hypothesis that genetic differentiation of R3 and R5 as exhibited by Krox 20 expression is a necessary component of the suppression of neural crest migration from these zones. Intellectual merit: This study will contribute to the understanding of a number of specific mechanisms of craniofacial patterning in vertebrates and in particular the role of neural crest in that patterning. Further, this project is part of a long-term study of the ways that developmental changes produce evolutionary changes. Finally, the study speaks to the constraints and possibilities of change in development, and helps reveal the ways in which developmental mechanisms may evolve.Broader impacts: The most important is educational. The previous grant supported the work of 14 undergraduates. Two were supported on REU supplements, including a woman of African American descent and a woman of Latin-American descent. Thirteen of these students were women. Educating undergraduates (and in particular under-represented groups) by providing research experience has been a life long pattern, and support by NSF will allow the Smith lab to continue to contribute to science education. In addition, during the past 10- years of NSF funding one of the larger collections of marsupial embryos in the world has accumulated. In the past two years this collection has been used by individuals from Finland, Germany, Brazil and the US. Further funding will support this collection. .