Histological and molecular features provide insights to consider Ciona robusta gut a suitable model to study gut physiology and evolution

This work proposes an overview of the anatomy and the molecular features of the C. robusta gut, focusing on the adult stage. This protochordate shares fundamental functional and morphogenetic molecules with vertebrates and, importantly, possess a non-duplicated and fully sequenced genome. While several similarities in the com-partmentalization of the digestive system in Ciona and mouse have already been shown, the detailed mechanisms at the basis of this regionalization and its associat-ed functionalities remain poorly understood. We investigated at the histological level tissue architecture along the intestinal an-tero-posterior axis of this ascidian. The RNAseq analysis was performed to identify and to reconstruct key signaling pathways and molecular component to elucidate both evolutionary and functional features of the digestive tract of this protochor-date. Moreover, we applied a systemic approach to compare the ascidian anatomi-cal and molecular features with a mammalian model. Understanding the conservation and evolution of the molecular mechanisms act-ing to establish cell types and their function is of pivotal importance in defining ma-jor aspects of animal evolution. Within this context, our results highlight some as-pects of gut evolution and physiology that may be also relevant for vertebrate and human biology, with consequent biomedical implications.