当某人做事犹豫，举棋不定时，人们通常这样开玩笑说，“不要做一只青蛙！” 当然被笑称为青蛙，其目的实际上是增强该人的自信。 但事实上青蛙是真正的赢家 - 至少从进化生物学的观点上来说。
来自德国 弗里德里希. 席勒 耶拿大学的Lennart Olsson教授说：“在今天已知的近6000个物种中，从数据上来说，青蛙是优于其他两栖类动物的高等级生物，甚至对哺乳动物来说，也是如此。”Olsson教授的研究团队通过对特种生物的研究找寻这些动物进化成功的秘诀。来自Olsson教授团队的Jennifer Schmidt解释说:“我们感兴趣的是：青蛙是如何在如此多样的种类中发展以及是怎样的进化发展让青蛙获得如此巨大的成功。”
它们进化的成功完全可以从青蛙的脸部展现出来：蝌蚪头部附近区域的某种软骨的构造和骨结构属于青蛙的“创新”。 这种结构只能在青蛙的口部区域找到。它们使蝌蚪- 南非爪蛙（Xenopus laevis）- 特别善于咬碎来自土壤和石头之间的植物或通过水过滤这些食物。 Jennifer Schmidt和来自乌尔姆的同事们一起将最新的研究刚在科学杂志“解剖学期刊”上发表。 分析这些对蝌蚪形态特色发展的核心因素。通过之前的分析，我们已经得知：基因“FOXN3”对爪蛙胚胎的头部发展起着关键作用。“该基因也对软骨，骨骼和肌肉的正常发展负责”。詹妮弗施密特解释道。
在新近发表的研究报告中，25岁的博士生和阿登纳基金会的奖学金获得者Jennifer Schmidt分析爪蛙的幼体在“FOXN3”基因被切断的情况下，与未经处理的幼体存在的区别。Jennifer Schmidt 说：“ 我们通过微电子CT技术分析显示，没有完整“FOXN3”基因的幼体在一定时间内的生长发育是正常的，但之后的成长趋缓。” “总的来说，这些被切断“FOXN3”基因的幼体成长相对较慢”。 它们大多数软骨. 骨骼和肌肉的发育不正常。同时也出现变形和丧失部分功能的情况。
然而，并非所有的软骨，肌肉受切断基因的影响。Olsson教授指出。“我们能够证明的”FOXN3“最重要的影响是口部区域的软骨和鳃的发育。” 这种组织结构属于青蛙进化中新发展的典型特征，这是在其他种类的两栖动物中无法找到的。Jennifer Schmidt将在她的论文进一步分析。“我们将要比较爪蛙与其他两栖类动物的胚胎的发展，” 这位动物研究者如是说。研究出遗传基因控制的这种生物在进化过程中的发展变化到底到达怎样的一个程度，这将非常有趣。（生物谷Bioon.com）
生物谷推荐原文出处：
J Anat. 2010. doi: 10.1111/j.1469-7580.2010.01315.x.
A role for FoxN3 in the development of cranial cartilages and muscles in Xenopus laevis (Amphibia: Anura: Pipidae) with special emphasis on the novel rostral cartilages
Jennifer Schmidt1, Maximilian Schuff2, Lennart Olsson1
Keywords:forkhead box genes;muscle morphogenesis;neural crest;novelties;rostralia;Xenopus laevis
Abstract
The origin of morphological novelties is a controversial topic in evolutionary developmental biology. The heads of anuran larvae have several unique structures, including the supra- and infrarostral cartilages, the specialised structure of the gill basket (used for filtration), and novel cranial muscle arrangements. FoxN3, a member of the forkhead/winged helix family of transcription factors, has been implicated as important for normal craniofacial development in the pipid anuran Xenopus laevis. We have investigated the effects of functional knockdown of FoxN3 (using antisense oligonucleotide morpholino) on the development of the larval head skeleton and the associated cranial muscles in X. laevis. Our data complement earlier studies and provide a more complete account of the requirement of FoxN3 in chondrocranium development. In addition, we analyse the effects of FoxN3 knockdown on cranial muscle development. We show that FoxN3 knockdown primarily affects the novel skeletal structures unique to anuran larvae, i.e. the rostralia or the fine structure of the gill apparatus. The articulation between the infrarostral and Meckel’s cartilage is malformed and the filigreed processes of the gill basket do not develop. Because these features do not develop after FoxN3 knockdown, the head morphology resembles that in the less specialised larvae of salamanders. Furthermore, the development of all cartilages derived from the neural crest is delayed and cranial muscle fibre development incomplete. The cartilage precursors initially condense in their proper position but later differentiate incompletely; several visceral arch muscles start to differentiate at their origin but fail to extend toward their insertion. Our findings indicate that FoxN3 is essential for the development of novel cartilages such as the infrarostral and other cranial tissues derived from the neural crest and, indirectly, also for muscle morphogenesis.
