當(dāng)某人做事猶豫，舉棋不定時(shí)，人們通常這樣開(kāi)玩笑說(shuō),，“不要做一只青蛙！” 當(dāng)然被笑稱為青蛙,，其目的實(shí)際上是增強(qiáng)該人的自信,。 但事實(shí)上青蛙是真正的贏家 - 至少?gòu)倪M(jìn)化生物學(xué)的觀點(diǎn)上來(lái)說(shuō)。
來(lái)自德國(guó) 弗里德里希. 席勒 耶拿大學(xué)的Lennart Olsson教授說(shuō)：“在今天已知的近6000個(gè)物種中,，從數(shù)據(jù)上來(lái)說(shuō),，青蛙是優(yōu)于其他兩棲類(lèi)動(dòng)物的高等級(jí)生物，甚至對(duì)哺乳動(dòng)物來(lái)說(shuō),，也是如此,。”Olsson教授的研究團(tuán)隊(duì)通過(guò)對(duì)特種生物的研究找尋這些動(dòng)物進(jìn)化成功的秘訣。來(lái)自O(shè)lsson教授團(tuán)隊(duì)的Jennifer Schmidt解釋說(shuō):“我們感興趣的是：青蛙是如何在如此多樣的種類(lèi)中發(fā)展以及是怎樣的進(jìn)化發(fā)展讓青蛙獲得如此巨大的成功,。”
它們進(jìn)化的成功完全可以從青蛙的臉部展現(xiàn)出來(lái)：蝌蚪頭部附近區(qū)域的某種軟骨的構(gòu)造和骨結(jié)構(gòu)屬于青蛙的“創(chuàng)新”,。 這種結(jié)構(gòu)只能在青蛙的口部區(qū)域找到。它們使蝌蚪- 南非爪蛙（Xenopus laevis）- 特別善于咬碎來(lái)自土壤和石頭之間的植物或通過(guò)水過(guò)濾這些食物,。 Jennifer Schmidt和來(lái)自烏爾姆的同事們一起將最新的研究剛在科學(xué)雜志“解剖學(xué)期刊”上發(fā)表,。 分析這些對(duì)蝌蚪形態(tài)特色發(fā)展的核心因素。通過(guò)之前的分析,，我們已經(jīng)得知：基因“FOXN3”對(duì)爪蛙胚胎的頭部發(fā)展起著關(guān)鍵作用,。“該基因也對(duì)軟骨，骨骼和肌肉的正常發(fā)展負(fù)責(zé)”,。詹妮弗施密特解釋道,。
在新近發(fā)表的研究報(bào)告中，25歲的博士生和阿登納基金會(huì)的獎(jiǎng)學(xué)金獲得者Jennifer Schmidt分析爪蛙的幼體在“FOXN3”基因被切斷的情況下,，與未經(jīng)處理的幼體存在的區(qū)別。Jennifer Schmidt 說(shuō)：“ 我們通過(guò)微電子CT技術(shù)分析顯示,，沒(méi)有完整“FOXN3”基因的幼體在一定時(shí)間內(nèi)的生長(zhǎng)發(fā)育是正常的,，但之后的成長(zhǎng)趨緩。” “總的來(lái)說(shuō),，這些被切斷“FOXN3”基因的幼體成長(zhǎng)相對(duì)較慢”,。 它們大多數(shù)軟骨. 骨骼和肌肉的發(fā)育不正常。同時(shí)也出現(xiàn)變形和喪失部分功能的情況,。
然而,，并非所有的軟骨,，肌肉受切斷基因的影響。Olsson教授指出,。“我們能夠證明的”FOXN3“最重要的影響是口部區(qū)域的軟骨和鰓的發(fā)育,。” 這種組織結(jié)構(gòu)屬于青蛙進(jìn)化中新發(fā)展的典型特征，這是在其他種類(lèi)的兩棲動(dòng)物中無(wú)法找到的,。Jennifer Schmidt將在她的論文進(jìn)一步分析,。“我們將要比較爪蛙與其他兩棲類(lèi)動(dòng)物的胚胎的發(fā)展，” 這位動(dòng)物研究者如是說(shuō),。研究出遺傳基因控制的這種生物在進(jìn)化過(guò)程中的發(fā)展變化到底到達(dá)怎樣的一個(gè)程度,，這將非常有趣。（生物谷Bioon.com）
生物谷推薦原文出處：
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.
