Evolutionary novelties in amphibian head development: The roles of FoxN3 and functionally related genes.

进化新奇事物的起源是进化生物学中一个长期存在的问题。发育过程和机制的变化必然是新的解剖结构的基础，但这究竟是如何工作的仍然是一个具有挑战性的问题。我们将探讨FoxN3和功能相关基因的作用，独特的幼虫头部骨骼结构和肌肉的两栖类幼虫的3个物种，蝾螈与食肉幼虫（Ambystoma mexicanum）和蝌蚪从两个青蛙物种，其中一个是一个广义的食草动物（铃蟾东方）和一个物种具有高度专业化的中层水悬浮液喂养幼虫（非洲爪蟾）。一个Morpholinobased敲低FoxN3功能被证明会影响几个独特的幼虫结构，只有在青蛙蝌蚪中发现，如精心制作的，丝状结构的鳃篮必要的过滤器喂养，和额外的嘴结构作为独特的新奇存在于青蛙蝌蚪。FoxN3在不同脊椎动物中的基因结构和蛋白质序列高度保守，或者它所参与的遗传网络是如何获得这些新功能的？在一个比较的方法，我们将分析两栖类物种的幼虫头部解剖结构的巨大差异，以及它们的发展是如何由FoxN3调节，并通过基因调控或调节FoxN3。此外，通过使用不同的组织学和分子生物学技术，我们将研究FoxN3嵌入的信号级联，并阐明这些不同物种之间FoxN3通路的差异。基于这些详细的经验数据，我们的目标是开发一个通用模型的解剖学新奇的演变。

The origin of evolutionary novelties is a long-standing issue in evolutionary biology. Changes in developmental processes and mechanisms must underlie novel anatomical structures, but exactly how this works remains a challenging question. We will investigate the role of FoxN3 and functionally related genes for the development of unique larval head skeletal structures and muscles in amphibian larvae of 3 species, a salamander with a carnivorous larva (Ambystoma mexicanum) and tadpoles from two frog species, one in which the larva is a generalised grazer (Bombina orientalis) and one species with a highly specialized mid-water suspension feeding larva (Xenopus laevis). A Morpholinobased knock-down of FoxN3 function was shown to affect several unique larval structures only found in frog tadpoles, such as the elaborate, filigreed structure of the gill basket necessary for filter feeding, and the extra mouth structures present as unique novelties in frog tadpoles. How did FoxN3, which is highly conserved in gene structure and protein sequence among different vertebrates, or the genetic network that is it part of, gain these new functions? In a comparative approach, we will analyze amphibian species with drastic differences in larval head anatomy and how their development is regulated by FoxN3, and by genes regulated by or regulating FoxN3. Moreover, by using different histological and molecular-biological techniques, we will investigate the signal cascade in which FoxN3 is embedded and elucidate differences in the pathway of FoxN3 between these distinct species. Based on such detailed empirical data, our aim is to develop a general model for the evolution of anatomical novelties.