Dissertation Improvement: Elucidation of Hominid Vertebropelvic Evolution via Observational and Experimental Analyses of Murine Embryogenetics and Avian Developmental Biology

人类脊柱和骨盆的胚胎学和发育在广泛的背景下都很重要，包括人类出生缺陷的病因和原因，以及躯干、骨盆和下肢的正常生长和成熟。其他重要的领域包括确定影响整体骨盆形状的因素，这些因素会影响产科的困难和成功。这一区域的解剖结构也是我们理解人类和灵长类动物进化过程的核心，尤其是下肢的出现和逐渐适应直立行走。一个完整的理解椎体和骨盆胚胎学最终需要他们的发育遗传学知识。在本研究中，将研究骶骨发育过程的三种胚胎学模型，包括其一些重要的特殊特征，如节段融合。每一个都对骶髂关节变化的速度和模式做出了不同的预测。要解决哪个模型最准确（因此最有可能是正确的），需要对该地区的发育生物学有更全面的了解。考虑到样本的稀缺性和灵长类动物漫长的发育时期（以及其他实际禁止），研究人员将对小鼠基因“敲除”进行骨骼分析，并检查小鸡胚胎学操作。这些都是直接检查灵长类动物和人类胚胎学过程的有效替代方法。最近的基因敲除（即特定基因正常活动的靶向失活）包括一些对正常脊柱和骨盆发育有深远影响的基因。这些包括Pitx1， Emx2， Fgf10和Fgf4-Fgf8。检查每一个的作用可以潜在地阐明骨盆带和下肢发育（因此自然选择）“单位”的核心方面，并澄清骨盆骨和骶骨之间的发育关系。研究人员将对其中一种基因“失活”的小鼠进行高分辨率微ct扫描。将使用NIH软件对每个突变体的骨盆和脊柱的三维结构进行定量测量。同样的程序将应用于同一品系的正常小鼠。此外，将在引入鹌鹑供体细胞移植的雏鸡中检查骶骨和骨盆胚胎学组织的命运图。这项技术以前没有被用来回答关于人类椎骨盆发育的问题。结合这些数据（小鼠基因敲除和鸟类胚胎学操作）将增强我们对人类进化研究的一个至关重要和相对较新的途径的理解，即确定关键基因（及其下游目标）在塑造人类框架中的生物学效应。随着对人类基因组的了解不断深入，人类学家必须与时俱进，提高对那些对人类解剖学和进化至关重要的基因的理解。此外，有肢动物进化的更广泛问题，如蛇和鲸鱼的肢体丧失，以及脊柱分割变异的进化，有望通过本研究进一步阐明。将进行的大部分工作涉及支持和维护东北俄亥俄大学医学院（NEOUCOM）的微型ct实验室。该设施对目前涉及骨和软骨生长和发育的各种临床项目至关重要。这项工作还将加强世界范围的科学合作，因为将被检查的一些突变标本是在欧洲、日本、加拿大和美国开发的。已经安排了交换从这些标本得来的数据的协议。美国国家科学基金会的支持将允许至少一名人类学研究生完成博士学位。最后，加强我们对这些基本发育过程的理解，很可能对进一步提高我们诊断和治疗严重胚胎学缺陷的能力至关重要。

The embryology and development of the human vertebral column and pelvis are important in a broad range of contexts, including the etiology and causation of human birth defects, as well as the normal growth and maturation of the trunk, pelvis, and lower limb. Other important areas include the identification of factors that affect overall pelvic form in ways that impact obstetric difficulty and success. The anatomy of this region is also central to our understanding of the process of human and primate evolution, especially the appearance and progressive adaptation of the lower limb to upright walking. A complete understanding the vertebral and pelvic embryology ultimately requires knowledge of their developmental genetics. In this research, three embryological models of the developmental progress of the sacrum, including a number of its important special features, such as segmental fusion, will be examined. Each makes different predictions with respect to the tempo and mode of sacroiliac change. Resolving which model is most accurate (and therefore most likely to be correct) requires a more thorough knowledge of this region's developmental biology. Given the rarity of specimens and the prolonged developmental period of primates (and other practical prohibitions as well), the researchers will perform skeletal analyses of mouse gene "knockouts" and examine chick embryological manipulations. These are effective alternatives to direct examination of the embryological processes in primates and humans. Recent gene knockouts (i.e., the targeted deactivation of a specific gene's normal activity) include a number that have a profound effect on normal spine and pelvis development. These include Pitx1, Emx2, Fgf10, and Fgf4-Fgf8. Examination of the role of each can potentially illuminate central aspects of the developmental (and thereby naturally selected) "units" of the pelvic girdle and lower limb, as well as clarify the developmental relationships between the pelvic bones and sacrum. High resolution microCT scans of mice in which one of these genes has been "deactivated" will be examined. Quantitative measures will be made of the three dimensional structure of the pelvis and spine in each mutant using NIH software. Identical procedures will be applied to normal mice of the same strain. In addition, fate maps of embryological tissues of the sacrum and pelvis will be examined in chicks in which transplantations of quail donor cells have been introduced. This technique has not been used previously to answer questions about vertebropelvic development in humans. Combining these data (mouse gene knockouts and avian embryological manipulation) will enhance our understanding of a crucially important and relatively new avenue of human evolutionary research, i.e., determining the biological effects of key genes (and their downstream targets) in shaping the human frame. As understanding of the human genome unfolds, anthropologists must keep pace by improving our understanding of those genes which are central to human anatomy and evolution. In addition, broader issues of evolution in limbed animals such as limb loss in snakes and whales, as well as the evolution of variations of spinal segmentation promise to be further illuminated by this research. A substantial proportion of the work to be conducted involves support and maintenance of the microCT laboratory at the Northeast Ohio Universities College of Medicine (NEOUCOM). This facility is vital to a variety of current clinical projects involving bone and cartilage growth and development. The work will also enhance world-wide scientific cooperation as a number of the mutant specimens that will be examined have been developed in Europe, Japan, Canada, as well as the United States. Agreements for the exchange of data derived from these specimens have already been arranged. NSF support will allow at least one anthropology graduate student to complete the Ph.D. Finally, enhancement of our understanding of these fundamental developmental processes is very likely to prove vital in furthering our capacity to diagnose and treat serious embryological defects.