Rapid Hox gene evolution and the arthropod body plan

理解进化论对于理解基础生物学至关重要，对于科学的应用方面，包括生物与环境的相互作用，也同样重要。这个项目探索被称为Hox基因的调控基因的进化变化，并询问它们如何影响动物的发育。Hox基因是模式基因，编码控制胚胎发育的转录因子，这些转录因子在整个动物界都非常保守。这一发现最初令人惊讶，因为Hox基因最初是在果蝇中发现的，这种基因突变会导致奇怪的表型(称为同源异型转化)，即一个身体部位被转化为不同的身体部位。然而，对这些基因的克隆表明，它们存在于所有动物中，包括人类。此外，研究表明，哺乳动物的基因可以替代苍蝇的基因，并在苍蝇中表达时概括苍蝇同源物的功能，这突显了这些基因和基因产物在不同生物之间的高度相关性。那么，每种动物是如何实现其特定的身体形态的呢？该项目通过跟踪HOX基因福氏Tarazu(FTZ)的进化变化来解决这个问题。FTZ在发育中的作用已被证明在进化过程中由于其蛋白质编码序列和表达模式的变化而发生变化。该项目中进行的研究将确定这些变化发生在进化史上的时间点，并使用代表进化树不同分支的活动物，将确定它们如何影响身体模式。此外，该奖项还将用于培养3名博士生和至少3名本科生。

Understanding evolution is critical to understanding basic biology and is equally important for applied aspects of science, including organismal interactions with the environment. This project probes evolutionary changes in regulatory genes, called Hox genes, and asks how they have impacted animal development. The Hox genes are patterning genes that encode transcription factors controlling embryonic development, which are remarkably conserved throughout the animal kingdom. This finding was initially surprising because Hox genes were first identified in fruit flies, where mutations result in bizarre phenotypes (called homeotic transformations) in which one body part is transformed to a different body part. However, cloning of these genes revealed that they are present in all animals, including humans. In addition, studies have shown that genes from mammals can substitute for those of the fly and recapitulate functions of the fly homologs when expressed in the fly, underscoring the high degree of relatedness of these genes and gene products among different organisms. How then does each animal achieve its own specific body form? This project addresses the question by tracking the evolutionary changes in one Hox gene, fushi tarazu (ftz). The roles of ftz in development have been shown to change during evolution due to changes in both its protein coding sequence and its expression pattern. Studies undertaken in this project will identify the points in evolutionary history at which these changes occurred and using living animals that represent different branches of an evolutionary tree, will determine how they impacted body patterning. In addition, this award will contribute to the training of three Ph.D. students and at least 3 undergraduate students.