Project description:Tunicate ascidians exhibit metamorphosis that converts tadpole, swimming larva into immotile adult. In ascidian Ciona intestinalis, the mutant tail regression failed (trf) which shows defects in the metamorphosis was previously reported (Nakayama-Ishimura et al., 2009). In the metamorphosis process, trf larvae settle normally with their adhesive papillae, but do not start tail regression, papillae retraction and sensory vesicle retraction, while development of adult organs proceed. To understand the molecular mechanism of the metamorphosis, microarray analysis of trf mutant was performed.
Project description:Tunicates, including ascidians, are recognized as the true “sister group” of vertebrates and are emerging as models to study the development and degeneration of central nervous system (CNS). Ascidian larvae have the typical chordate body plan that includes a dorsal neural tube. During their metamorphosis, a deep tissue reorganization takes place, with some tissues that degenerate while others develop to become functional during the adult life. The larval CNS also degenerates and most neurons disappear, making room to the formation of adult CNS. The genome of the ascidian Ciona intestinalis has been sequenced and annotated, with several CNS specific genes that have been characterized, revealing specification mechanisms shared with humans. These features make ascidian metamorphosis a good model to study the mechanisms underlying physiological CNS degeneration and to compare them to the pathological condition typical of neurodegenerative diseases. In order to shed light on the molecular determinants of C. intestinalis metamorphosis and neurodegeneration, we analyzed its transcriptome at three stages of development: swimming larva (SwL, Hotta stage 28), settled larva (SetL, Hotta stage 32) and metamorphosing larva (MetL, Hotta stage 34). Supported by SoE-SEED-2020 Grant, University of Milan.
Project description:A genomic overview of in vivo binding of a transcription factor ZicL in the ascidian gastrula embryo. ZicL is a key regulator of the early ascidian development, and so called 'master-regulatory genes' for mesodermal and neural tissues are under the control of ZicL. Keywords: ChIP-chip
Project description:A genomic overview of in vivo binding of a transcription factor MyoD in the ascidian gastrula embryo. MyoD is known to be essential and sufficient for differentiation of the muscle. Keywords: ChIP-chip
Project description:During development, stem and progenitor cells divide and transition through germ layer- and lineage-specific multipotent states to generate the diverse cell types that compose an animal. Defined changes in biomolecular composition underlie the progressive loss of potency and acquisition of lineage-specific characteristics. For example, multipotent cardiopharyngeal progenitors display multilineage transcriptional priming, whereby both the cardiac and pharyngeal muscle programs are partially active and coexist in the same progenitor cells, while their daughter cells engage in a cardiac or pharyngeal muscle differentiation path only after cell division. Here, using the tunicate Ciona, we studied the acquisition of multilineage competence and the coupling between fate decisions and cell cycle progression. We showed that multipotent cardiopharyngeal progenitors acquire the competence to produce distinct Tbx1/10 (+) and (-) daughter cells shortly before mitosis, which is necessary for Tbx1/10 activation. By combining transgene-based sample barcoding with single cell RNA-seq (scRNA-seq), we uncovered transcriptome-wide dynamics in migrating cardiopharyngeal progenitors as cells progress through G1, S and G2 phases. We termed this process “transcriptome maturation”, and identified candidate “mature genes”, including the Rho GAP-coding gene Depdc1, which peak in late G2. Functional assays indicated that transcriptome maturation fosters cardiopharyngeal competence, in part through multilineage priming and proper oriented and asymmetric division that influences subsequent fate decisions, illustrating the concept of “behavioral competence”. Both classic feedforward circuits and coupling with cell cycle progression drive transcriptome maturation, uncovering distinct levels of coupling between cell cycle progression and fateful molecular transitions. We propose that coupling competence and fate decision with the G2 and G1 phases, respectively, ensures the timely deployment of lineage-specific programs.