Development of the house secreting epithelium, a major innovation of tunicate larvaceans, involves multiple homeodomain transcription factors

Developmental biology

Ragnhild Skinnes^1¹  Sara Sumic^1²  Yana Mikhaleva^1³ 

[1] Department of Biology, University of Bergen, Norway^2;Key Laboratory of Marine Genetics and Breeding, Ocean University of China, Ministry of Education, Qingdao 266003, China^3;Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt, 55, N-5008 Bergen, Norway^1

关键词: Evolution;    Novelties;    Tunicates;    Oikopleura;    Homeobox;    Fox;   

DOI  :  10.1016/j.ydbio.2018.09.006

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

The mechanisms driving innovations that distinguish large taxons are poorly known and essentially accessible via a candidate gene approach. A spectacular acquisition by tunicate larvaceans is the house, a complex extracellular filtration device. Its components are secreted by the oikoplastic epithelium which covers the animal trunk. Here we describe the development of this epithelium in larvae through the formation of specific cellular territories known to produce distinct sets of house proteins (Oikosins). It involves cell divisions and morphological differentiation but very limited cell migration. A diverse set of homeobox genes, most often duplicated in the genome, are transiently and site-specifically expressed in the trunk epithelium at early larval stages. Using RNA interference, we show that two prop duplicates are involved in the differentiation of a region on and around the dorsal midline, regulating morphology and the production of a specific oikosin. Our observations favor a scenario in which multiple homeobox genes and most likely other developmental transcription factors were recruited for this innovation. Their frequent duplications probably predated, but were not required for the emergence of the house.

【 授权许可】

CC BY