ABSTRACT Control of global protein synthesis through the assembly of stress granules (SGs) represents a strategy adopted by eukaryotic cells to face various stress conditions. TIAR, TTP and G3BP are key components of SGs, allowing the regulation of mRNA stability and thus controlling not only stress responses but also cell proliferation and differentiation. In the present work we aimed to investigate the role of tiar , ttp and g3bp during embryogenesis of the solitary ascidian Ciona robusta , both in physiological and stress conditions. We carried out CRISPR/Cas9 knockout to evaluate the effects on normal embryonic development, and gene reporter assays to study time and tissue specificity of gene expression, together with whole mount ISH and qRT-PCR. To induce acute stress conditions, we used iron and cadmium as “essential” and “non-essential” metals, respectively. Our results highlight, for the first time, the importance of tiar, ttp and g3bp in the control of development of mesendodermal tissue derivatives during embryogenesis of an invertebrate chordate. HIGHLIGHTS - Mesenchyme, nervous cells, and endoderm are the embryonic regions mainly transcribing cr-tiarx1 , cr-ttp and cr-g3bp2 during metal stress conditions. - Only cr-ttp transcription is regulated at mid gastrula stage. - The highest transcription levels are reached in hatching larvae after iron exposure. - cr-tiarx1 , cr-ttp and cr-g3bp2 knockouts resulted in impaired embryogenesis.
