Making Waves: From Pattern to Structure in Dental Evolution

牙齿模式——牙齿在颌中的数量、位置和形态——一直是灵长类动物和人类适应辐射的一个主要因素。牙齿的变异使特化成为可能，这是灵长类动物和原始人进化的诊断特征之一，牙齿是化石记录中保存下来的最重要的证据之一。牙列可以看作是沿着胚胎牙板生长的一组嵌套的“波”。波峰首先确定牙齿沿颌的位置。随后的峰形在牙齿内雕刻尖，结果被矿化固定在适当的位置。这种波浪形的模式是由扩散（细胞外）信号因子之间的定量相互作用产生的。该项目的第一个目标是使用改变这些因子表达水平的转基因小鼠，看看是否可以产生类似自然发生的变异。通过制造和杂交这些信号因子表达增强和减少的动物，更好地了解模式过程的实际工作原理。其次，并非所有与牙齿形状有关的基因都是已知的。基因定位方法将应用于圣安东尼奥西南生物医学研究基金会的大型狒狒系谱中牙齿变异的数据，这些数据是由德克萨斯州和伊利诺伊大学的同事收集的。同样，基因定位将在市售的重组近交实验室小鼠中进行，在这些小鼠中发现了与在狒狒中观察到的相似的变异。基因表达研究和生物信息学（基于计算机的）方法将探索可能携带影响牙齿图案的基因的染色体区域，以识别这些基因，确定它们的表达是如何被调节的，并表征它们在胚胎小鼠牙齿发育中的外观。这个项目的广泛影响将远远超出人类学，扩展到一般的生物学，因为所有生命，植物，动物和人类的最基本问题之一是：生物体的复杂模式是如何形成的？牙列可以作为生命谱系中许多类似过程的模型。像DNA克隆和序列数据这样的技术材料将提供给研究界，结果将通过各种评论和概述文章向科学界和公众开放。该实验室通常包括本科生和少数民族，以及国内和国际合作。这项工作通常包括在所教授的课程中，并且NSF REU补充经常支持实验室的本科生。

Dental patterning-the number, location, and morphology of teeth in the jaws-has been a major factor in primate and human adaptive radiation. The specializations made possible by dental variation are among the diagnostic characteristics of primate and hominid evolution, and teeth are among the most important evidence preserved in the fossil record. The dentition can be viewed as a set of nested 'waves' of growth along the embryonic dental lamina. The wave-peaks first determine the position of teeth along the jaws. Subsequent peaks sculpt the cusps within teeth, and the results are fixed in place by mineralization. This wavelike pattern is generated by quantitative interactions among diffusible (extracellular) signaling factors. The first objective of this project is to use transgenic mice with altered expression levels of these factors, to see whether variation resembling that occurring naturally can be produced. By making and then interbreeding animals with enhanced and reduced expression of these signaling factors, a better understanding of how the patterning process actually works. Second, not all genes involved in dental patterning are yet known. Gene mapping methods will be applied to data on dental variation in a large baboon genealogy at the Southwest Foundation for Biomedical Research in San Antonio, data collected by colleagues in Texas and at the University of Illinois. Similarly, gene mapping will be done in commercially available recombinant inbred laboratory mice, in which variation similar to that observed in the baboons has been found. Chromosomal regions that may carry genes affecting dental patterning will be explored by gene-expression studies and bioinformatic (computer-based) methods to identify those genes, determine how their expression is regulated, and characterize their appearance in developing teeth in embryonic mice.This broader impact of this project will extend well beyond anthropology, to biology in general, because one of the most fundamental questions of all of life, plant, animal and human is: How do complex patterns of which organisms are built come about? The dentition can serve as a model for many similar processes across the spectrum of life. Technical materials like DNA clones and the sequence data will be made available to the research community, and the results will be made accessible to the scientific and general public through various review and overview articles. The laboratory routinely includes undergraduates and minorities, as well as national and international collaborations. This work is routinely included in courses taught, and NSF REU supplements often support undergraduates in the laboratory.