2023年11月1日，《自然》杂志在线发表了美国斯坦福大学C. J. Lowe等研究人员的最新合作成果。该研究揭示成年棘皮动物中前后轴行成的分子证据。

研究人员表示，棘皮动物的五角辐射身体结构起源于双侧祖先，这是最持久的动物学难题之一。由于棘皮动物以形态新颖而著称，因此即使是与它们的双侧亲缘动物进行最基本的轴向比较也存在问题。

为了重新探讨这一经典问题，研究人员利用保守的前后轴向分子标记来确定，棘皮动物高度衍生的成年体平面是否掩盖了其与其他半脊椎动物的潜在模式相似性。研究人员利用RNA层析技术和原位杂交技术，在海星Patiria miniata中研究了一系列保守转录因子的表达情况，这些转录因子在后口动物和其他双侧动物的前后轴极性的建立过程中发挥了公认的作用。这些标记物在P. miniata伏跗关节外胚层的相对空间表达显示出与其他畸形动物的相似性，每条射线的中线代表最前方的区域，而最外侧的部分则显示出更多的后方特征。

令人震惊的是，海星的外胚层没有一个区域表现出具有特征性的双侧动物躯干遗传模式化程序。这一发现表明，从外胚层模式化的角度来看，棘皮动物大多是头状动物，并为重新评估导致棘皮动物衍生的成体体型演化事件提供了发育依据。

附：英文原文

Title: Molecular evidence of anteroposterior patterning in adult echinoderms

Author: Formery, L., Peluso, P., Kohnle, I., Malnick, J., Thompson, J. R., Pitel, M., Uhlinger, K. R., Rokhsar, D. S., Rank, D. R., Lowe, C. J.

Issue&Volume: 2023-11-01

Abstract: The origin of the pentaradial body plan of echinoderms from a bilateral ancestor is one of the most enduring zoological puzzles1,2. Because echinoderms are defined by morphological novelty, even the most basic axial comparisons with their bilaterian relatives are problematic. To revisit this classical question, we used conserved anteroposterior axial molecular markers to determine whether the highly derived adult body plan of echinoderms masks underlying patterning similarities with other deuterostomes. We investigated the expression of a suite of conserved transcription factors with well-established roles in the establishment of anteroposterior polarity in deuterostomes3,4,5 and other bilaterians6,7,8 using RNA tomography and in situ hybridization in the sea star Patiria miniata. The relative spatial expression of these markers in P. miniata ambulacral ectoderm shows similarity with other deuterostomes, with the midline of each ray representing the most anterior territory and the most lateral parts exhibiting a more posterior identity. Strikingly, there is no ectodermal territory in the sea star that expresses the characteristic bilaterian trunk genetic patterning programme. This finding suggests that from the perspective of ectoderm patterning, echinoderms are mostly head-like animals and provides a developmental rationale for the re-evaluation of the events that led to the evolution of the derived adult body plan of echinoderms.

DOI: 10.1038/s41586-023-06669-2

Source: https://www.nature.com/articles/s41586-023-06669-2