Sanchez Eugenia, Küpfer Eliane, Goedbloed Daniel J, Nolte Arne W, Lüddecke Tim, Schulz Stefan, Vences Miguel, Steinfartz Sebastian
Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.
Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany.
J Exp Zool B Mol Dev Evol. 2018 Mar;330(2):96-108. doi: 10.1002/jez.b.22792. Epub 2018 Mar 5.
The postembryonic development of amphibians has been characterized as divided into three predominant periods, hereafter named primary developmental stages: premetamorphosis (PreM), prometamorphosis (ProM), metamorphic climax (Meta), and completion of metamorphosis (PostM), largely based on examination of anuran development. Here, we categorized the postembryonic development of larvae of a poisonous fire salamander (Salamandra salamandra) by integrating morphology and gene expression (transcriptomic) data. Morphological analysis revealed three distinct clusters suggestive of PreM, ProM, and Meta, which were confirmed in parallel by microarray-derived gene expression analysis. In total, 3,510 probes targeted transcripts differentially expressed between the clusters we identified. Genes upregulated in PreM related to organogenesis, and those upregulated in Meta underlie structural proteins and related to development of anatomical structures and pigmentation. Biosynthesis pathways of pigments (pteridines and melanin) were upregulated during late ProM and Meta. Gas chromatographic analysis of alkaloids indicated the onset of steroidal alkaloid biosynthesis at ProM. When comparing gene expression in the fire salamander to that in other amphibians-three anurans, Xenopus laevis, X. tropicalis, and Michrohyla fissipes, and one caudate, Ambystoma mexicanum- we identified genes with conserved expression patterns involved in basic metamorphic processes such as skin restructuring and tail fin resorption. Our results support that primary stages of postembryonic development in caudates are homologous to those of anurans, and offer a baseline for the study of the evolution of developmental modes.
两栖动物的胚后发育主要分为三个时期，以下称为主要发育阶段：前变态期（PreM）、变态前期（ProM）、变态高峰期（Meta）和变态完成期（PostM），这主要是基于对无尾目发育的研究。在此，我们通过整合形态学和基因表达（转录组学）数据，对有毒火蝾螈（Salamandra salamandra）幼体的胚后发育进行了分类。形态学分析揭示了三个不同的聚类，分别暗示了前变态期、变态前期和变态高峰期，这通过微阵列衍生的基因表达分析得到了平行证实。总共3510个探针靶向了我们鉴定的聚类之间差异表达的转录本。在前变态期上调的基因与器官发生相关，而在变态高峰期上调的基因则是结构蛋白的基础，与解剖结构和色素沉着的发育有关。色素（蝶啶和黑色素）的生物合成途径在变态前期后期和变态高峰期上调。生物碱的气相色谱分析表明，甾体生物碱生物合成在变态前期开始。当将火蝾螈的基因表达与其他两栖动物（三种无尾目动物，非洲爪蟾、热带爪蟾和姬蛙，以及一种有尾目动物，墨西哥钝口螈）的基因表达进行比较时，我们鉴定出了具有保守表达模式的基因这些基因参与皮肤重塑和尾鳍吸收等基本变态过程。我们的结果支持有尾目动物胚后发育的主要阶段与无尾目动物的主要阶段同源，并为发育模式进化的研究提供了一个基线。
