根据协调局部细胞形态发生的空间和时间线索,在发育过程中形成(并在再生过程中重新形成)。尾鳍是大多数鱼类用于推进的主要附属物,并表现出一系列适应不同游泳策略的不同形态,然而,负责产生这些不同形状的分子机制仍然是未知的。在斑马鱼中,尾鳍呈叉形,外围有较长的支持性骨射线,中心有较短的射线。这里,我们证明了过早的,在晚期胚胎发育过程中,声波刺猬a(shha)过表达的瞬时脉冲会导致中央射线的过度增殖和生长,导致成年尾鳍长成三角形,截断形状。全球和区域异位shha过度表达都足以改变鳍的形状,叉形可以通过随后用规范Shh途径的拮抗剂进行治疗来挽救。诱导的截短鳍显示出减少的鳍射线数,并且无法形成通常将背侧和腹侧鳍叶分开的充膜舒张。当分叉的鳍再生其原始的分叉形态时,截断鳍再生截断,这表明,在胚胎发生过程中,通过短暂的治疗可以永久性地改变鳍状射线的位置记忆。射线鳍鱼已经进化出了广泛的尾鳍形态,从截断到分叉,当前的工作提供了对可能构成这种形状多样性的发展机制的见解。
Appendage shape is formed during development (and re-formed during regeneration) according to spatial and temporal cues that orchestrate local cellular morphogenesis. The caudal fin is the primary appendage used for propulsion in most fish species, and exhibits a range of distinct morphologies adapted for different swimming strategies, however the molecular mechanisms responsible for generating these diverse shapes remain mostly unknown. In zebrafish, caudal fins display a forked shape, with longer supportive bony rays at the periphery and shortest rays at the center. Here, we show that a premature, transient pulse of sonic hedgehog a (shha) overexpression during late embryonic development results in excess proliferation and growth of the central rays, causing the adult caudal fin to grow into a triangular, truncate shape. Both global and regional ectopic shha overexpression are sufficient to alter fin shape, and forked shape may be rescued by subsequent treatment with an antagonist of the canonical Shh pathway. The induced truncate fins show a decreased fin ray number and fail to form the hypural diastema that normally separates the dorsal and ventral fin lobes. While forked fins regenerate their original forked morphology, truncate fins regenerate truncate, suggesting that positional memory of the fin rays can be permanently altered by a transient treatment during embryogenesis. Ray finned fish have evolved a wide spectrum of caudal fin morphologies, ranging from truncate to forked, and the current work offers insights into the developmental mechanisms that may underlie this shape diversity.