Evolutionary loss of melanogenesis
in the tunicate Molgula occulta
Claudia Racioppi, Maria Carmen Valoroso, Ugo Coppola, Elijah K. Lowe, C. Titus Brown, Billie J. Swalla, Lionel Christiaen, Alberto Stolfi, & Filomena Ristoratore
We found that the tunicate Molgula occulta has lost the genes encoding crucial enzymes for melanin synthesis, perhaps because its tail-less larvae do not swim and have no need for pigmented light- and gravity-sensing organs.
Evaluation and rational design of guide RNAs for efficient CRISPR/ Cas9-mediated mutagenesis in Ciona
Shashank Gandhi, Maximilian Haeussler, Florian Razy-Krajka, Lionel Christiaen, & Alberto Stolfi
We developed a novel pipeline for rapid yet accurate design, synthesis, and evaluation of efficient sgRNAs for high-throughput, tissue-specific CRISPR/Cas9 knockouts in Ciona embryos.
Migratory neuronal progenitors arise from the neural plate borders in tunicates
Alberto Stolfi, Kerrianne Ryan, Ian A. Meinertzhagen, & Lionel Christiaen
We show that a particular neuronal cell type in the tadpole larva of the tunicate Ciona, the bipolar tail neuron, shares a set of features with neural-crest-derived spinal ganglia neurons in vertebrates, hinting at the pre-vertebrate origins of the neural crest.
Tissue-specific genome editing in Ciona embryos by CRISPR/Cas9
Alberto Stolfi, Shashank Gandhi, Farhana Salek, & Lionel Christiaen
We report the first use of CRISPR/Cas9 for tissue-specific genome editing in the tunicate Ciona. Using this technique to disrupt the Ebf gene in different cell lineages, we revealed that its function is required for specification motor ganglion neurons and atrial siphon muscles.
Divergent mechanisms regulate conserved
cardiopharyngeal development and gene expression in distantly related ascidians
Alberto Stolfi*, Elijah Lowe*, Claudia Racioppi, Filomena Ristoratore, C. Titus Brown, Billie J. Swalla, & Lionel Christiaen (*equal contrib.)
Comparisons between the distantly related tunicates Molgula and Ciona reveal cryptic turnover
of regulatory mechanisms that underlie identical gene expression patterns.
Coordinated regulation of cholinergic motor neuron traits through a conserved terminal selector gene
Paschalis Kratsios, Alberto Stolfi, Michael Levine, & Oliver Hobert
We show that UNC-3/Ebf is a terminal selector for cholinergic motor neuron differentiation whose function is conserved across phylogeny, from C. elegans to Ciona.
Genetic and genomic toolbox of the chordate Ciona intestinalis
Alberto Stolfi & Lionel Christiaen
A review on the tools, techniques, and resources available to the Ciona geneticist, citing examples of studies that employed such strategies in the elucidation of gene function in Ciona: electroporation, transgenesis, genetic screens, and a preview of the emergence of genetic engineering platforms like CRISPR/Cas9.
Neural tube patterning by Ephrin, FGF, and Notch signaling relays
Alberto Stolfi, Eileen Wagner, J. Matthew Taliaferro, Seemay Chou, & Michael Levine
We show that the Ciona Motor Ganglion is patterned by sequential Ephrin/FGF/MAPK and Delta/Notch signaling events that lead to localized expression of conserved homeodomain codes for the specification of distinct neuronal subtypes.
Neuronal subtype specification in the spinal cord of a protovertebrate
Alberto Stolfi & Michael Levine
We used fluorescent reporter constructs to label and identify invariant but morphologically distinct moto- and interneuron subtypes in the Motor Ganglion of the Ciona larva. We also perturbed neuronal subtype specification in predictable ways by targeting specific transcription factors and signaling molecules.
Early chordate origins of the vertebrate second heart field
Alberto Stolfi, T. Blair Gainous, John J. Young, Alessandro Mori, Michael Levine, & Lionel Christiaen
We found that heart progenitor cells of the simple chordate Ciona also generate precursors of the pharyngeal muscles. These precursors express Islet and Tbx1/10, evocative of the splanchnic mesoderm that produces the lower jaw muscles and Second Heart Field of vertebrates. We propose that the last common ancestor of tunicates and vertebrates possessed multipotent cardiopharyngeal muscle precursors, and that their reallocation might have contributed to the emergence of the SHF.
Gene regulatory networks underlying the compartmentalization of the Ciona central nervous system
Kaoru S. Imai, Alberto Stolfi, Michael Levine, & Yutaka Satou
Here we document provisional gene regulatory networks operating in the developing central nervous system of Ciona, at single-cell resolution. This revealed a striking conservation in neural gene expression and patterning relative to vertebrates. More careful analysis revealed a role for FGF8 in patterning the Ciona hindbrain in a manner reminiscent of the midbrain/hindbrain boundary organizer in vertebrates.