海马具有非常奇特的体形特征，无腹鳍，尾鳍发生渐行性退化，雄海马具有孵育幼仔的育儿袋；但其独特体形的调控机理至今尚不清楚。同源异型盒基因是动物体形调节的关键基因，pitx1属于一种成对同源异型域转录因子，且已明确其在肢体形态发育过程中起主要的调控作用。前期研究发现海马pitx1蛋白序列中出现了大量的同聚氨基酸片段，利用转基因技术在斑马鱼中过表达海马pitx1基因，发现其胚胎尾巴严重弯曲，尾鳍停止发育，表明pitx1参与海马尾鳍的退化过程。在此基础上，本项目将从以下几个方面开展：（1）解析海马pitx1基因结构和进化特征；（2）研究海马pitx1基因的时空表达模式及其与尾鳍发育的相关性；（3）利用基因编辑技术和组学分析手段，探讨海马pitx1在尾鳍退化过程中的作用及其分子调控机理。本研究结果不仅有助于完善海马体形发育的调控网络，而且对理解脊椎动物的体形和演化规律都有重要的科学意义。

The seahorse has very unique body shape with no pelvic fin and progressive caudal fin loss, and male seahorse with brood pouch that incubate embryos. The mechanism of regulation of this unique body shape in the seahorse remains unclear. Homeobox genes are the key genes in animal body shape regulation. Pitx1 belongs to a paired homeobox transcription factor and has been identified as a major regulator of limb morphogenesis. Previous studies found that a large number of homopolymeric amino acid (HPAA) tracts were found in the pitx1 protein sequence of seahorse. The overexpression of the pitx1 gene in seahorse by transgenic technology showed that the tail of the embryo was severely bent and the caudal fin stopped its development, indicating that pitx1 is involved in the development of the caudal fin. On this basis, the project will be carried out in the following aspects. (1) To analyze the structure and evolution of pitx1 gene in the seahorse. (2) To study the spatial and temporal expression pattern of pitx1 gene in seahorse and its relationship with caudal fin development. (3) Using gene editing techniques and RNA-seq to explore the function of pitx1 in the seahorse's caudal fin loss and its role in signaling pathways. The findings of this project not only help to explore the molecular regulation mechanism of seahorse's morphology in depth, but also have important scientific significance on the origin and evolution of the vertebrate's morphology.