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是重要的，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。 其他重要领域包括确定影响整体骨盆形状的因素，这些因素影响产科的困难和成功。 这个区域的解剖学也是我们理解人类和灵长类进化过程的核心，特别是下肢的外观和直立行走的渐进适应。一个完整的理解脊椎和骨盆胚胎学最终需要他们的发育遗传学知识。在这项研究中，将检查骶骨发育过程的三种胚胎学模型，包括其一些重要的特殊功能，如节段融合。每一种都对骶髂关节变化的克里思和模式做出了不同的预测。解决哪个模型是最准确的（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。 鉴于标本的稀有性和灵长类动物发育期的延长（以及其他实际的禁令），研究人员将对小鼠基因“敲除”进行骨骼分析，并检查鸡的胚胎学操作。 这些是直接检查灵长类动物和人类胚胎过程的有效替代方法。 最近的基因敲除（即，特定基因正常活性的靶向失活）包括对正常脊柱和骨盆发育具有深远影响的许多基因。 这些包括Pitx 1，Emx 2，Fgf 10和Fgf 4-Fgf 8。 对每一个角色的检查可以潜在地阐明骨盆带和下肢的发育（从而自然选择）“单元”的中心方面，以及澄清骨盆骨和骶骨之间的发育关系。 高分辨率microCT扫描的小鼠，其中一个这些基因已被“失活”将被检查。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。相同的程序将应用于相同品系的正常小鼠。 此外，还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组织的命运图。 这项技术以前没有被用于回答有关人类脊椎骨盆发育的问题。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中一个至关重要且相对较新的途径的理解，即，确定关键基因（及其下游目标）在塑造人体结构中的生物学效应。随着对人类基因组的了解不断深入，人类学家必须跟上步伐，提高我们对那些对人类解剖学和进化至关重要的基因的了解。此外，有肢动物进化的更广泛问题，如蛇和鲸鱼的肢体丧失，以及脊椎分节变异的进化，有望通过这项研究得到进一步阐明。要进行的工作的很大一部分涉及支持和维护的microCT实验室在东北俄亥俄州大学医学院（NEOUCOM）。 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，因为欧洲、日本、加拿大和美国已经开发出了一些将被检查的突变标本。 已经安排了交换这些标本数据的协议。 NSF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，很可能证明对提高我们诊断和治疗严重胚胎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.