DISSERTATION RESEARCH: The Homology of Dermal Ossifications in Reptiles

大多数骨的形成有两种方式：通过软骨模型（软骨内骨）或直接在皮肤（真皮骨）中形成。龟壳和鳄鱼的鳞片是由真皮骨形成的，尽管它们发育的某些方面已经被很好地理解，但它们的发育是如何开始的还不清楚。一些研究人员提出，这些骨头来自一种叫做神经嵴的组织；然而，这一起源尚未得到证实。神经嵴是在脊椎动物胚胎的外胚层形成的组织，形成颅骨的真皮骨。一个独立的胚胎组织，即中胚层，为颅骨提供软骨内骨，并形成骨骼的其余部分。本研究以基因表达作为追踪神经嵴和中胚层对龟壳和鳄鱼鳞甲的贡献的手段。在其他脊椎动物神经嵴或中胚层中表达的基因将利用RNA杂交技术作为海龟和鳄鱼胚胎中这些组织的潜在标记物进行研究。本研究的系统学意义在于评估真皮骨的进化发育起源。这也有助于理解海龟与其他爬行动物的进化关系。这项研究利用了进化生物学和分子生物学的方法，以新的术语来分析一个非常古老的问题。通常，使用这些方法的研究是在模型系统上进行的，例如果蝇、青蛙、鸡或老鼠。通过对海龟和短吻鳄的研究，本研究扩展了可用于进化史研究的知识和技术资源。博士生是一名西班牙裔女性，她的训练范围很广，她通过研讨会、课程、科学会议和全球网络传播她的研究成果。

Most bone forms in one of two ways: through a cartilage model (endochondral bone) or directly in the skin (dermal bone). Turtle shells and crocodile scutes are formed of dermal bone, and although some aspects of their development are well understood, it is not clear how their development is initiated. Some researchers have proposed that these bones come from a tissue called the neural crest; however, this origin has not been demonstrated. The neural crest is a tissue formed in the ectoderm of the vertebrate embryo that contributes the dermal bones of the skull. A separate embryonic tissue, the mesoderm, contributes endochondral bone to the skull and forms the rest of the skeleton. This study investigates gene expression as a means to trace the contribution of neural crest and mesoderm to turtle shells and crocodile scutes. Genes expressed in neural crest or mesoderm in other vertebrate animals will be studied as potential markers for these tissues in turtle and alligator embryos using RNA hybridization techniques. The importance of this study for systematics lies in its assessment of the evolutionary developmental origin of dermal bone. It may also aid in understanding the evolutionary relationships of turtles to other reptiles.This study harnesses approaches from evolutionary biology and molecular biology to analyze a very old problem in new terms. Normally, studies using these methods are performed on model systems, such as fruit flies, frogs, chickens, or mice. By using turtles and alligators, this study expands the knowledge and technical resources that can be used for the study of evolutionary history. The doctoral student is a Hispanic female, her training is broad, and she disseminates her work through seminars, courses, scientific meetings, and the worldwide web.