Conservation of peripheral nervous system formation mechanisms in divergent ascidian embryos

• Published in: eLife Vol. 9
• Main Authors: Coulcher, Joshua F, Roure, Agnès, Chowdhury, Rafath, Robert, Méryl, Lescat, Laury, Bouin, Aurélie, Carvajal Cadavid, Juliana, Nishida, Hiroki, Darras, Sébastien
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 16.11.2020; eLife Sciences Publication; eLife Sciences Publications, Ltd; eLife Sciences Publications Ltd
• Subjects: Analysis; Animal biology; Animal genetics; Animals; ascidians; Biochemistry, Molecular Biology; Biodiversity; Cell Behavior; Cellular Biology; cis-regulation; Development Biology; Developmental Biology; developmental system drift; DNA binding proteins; Embryology and Organogenesis; Embryonic development; evo-devo; Evolutionary Biology; gene expression; Gene Expression Regulation, Developmental - physiology; Genes; Genetics; Genomes; Genomics; Invertebrate Zoology; Larva - growth & development; Life Sciences; Molecular biology; Molecular Networks; Morphogenesis; Peripheral Nervous System - embryology; Phylogeny; Populations and Evolution; Species Specificity; Transcription (Genetics); Urochordata - embryology; Urochordata - genetics; evo-devo; developmental system drift; evolutionary biology; ascidians; C. intestinalis; developmental biology; cis-regulation; gene expression
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.59157

Ascidians with very similar embryos but highly divergent genomes are thought to have undergone extensive developmental system drift. We compared, in four species ( and for Phlebobranchia, and for Stolidobranchia), gene expression and gene regulation for a network of six transcription factors regulating peripheral nervous system (PNS) formation in . All genes, but one in , were expressed in the PNS with some differences correlating with phylogenetic distance. Cross-species transgenesis indicated strong levels of conservation, except in , in gene regulation despite lack of sequence conservation of the enhancers. Developmental system drift in ascidians is thus higher for gene regulation than for gene expression and is impacted not only by phylogenetic distance, but also in a clade-specific manner and unevenly within a network. Finally, considering that is divergent in our analyses, this suggests deep conservation of developmental mechanisms in ascidians after 390 My of separate evolution.