Project description:Single-cell RNA-sequencing (scRNA-seq) of the developing small-spotted catshark (Scyliorhinus canicula) head was perform to better understand the evolution of neural crest cells in jawed vertebrates (gnathostomes). As most studies have focused on bony vertebrates (Osteichthyes), the small-spotted catshark provides insights into neural crest cells biology in cartilaginous fishes (Chondrichthyes), the only sister group of Osteichthyes. The 10x Genomics Chromium platform for single-cell transcriptomics was used to profile five key developmental stages: St.16-20, which include specified non-delaminating, delaminating, migratory, and early differentiating neural crest cells.Due to the limited availability of small-spotted catshark embryos, these five developmental stages were pooled together.
Project description:The retina, whose basic cellular structure is highly conserved across vertebrates, constitutes an accessible system for studying the central nervous system. In recent years, single-cell RNA-sequencing studies have uncovered cellular diversity in the retina of a variety of species, providing new insights on retinal evolution and development. However, similar data in cartilaginous fishes, the sister group to all other extant jawed vertebrates, are still lacking. Here, we present a single-nucleus RNA-sequencing atlas of the postnatal retina of the catshark Scyliorhinus canicula, consisting of the expression profiles for 17,438 individual cells from three female, juvenile catshark specimens. Unsupervised clustering revealed 22 distinct cell types comprising all major retinal cell classes, as well as retinal progenitor cells (whose presence reflects the persistence of proliferative activity in postnatal stages in sharks) and oligodendrocytes. Thus, our dataset serves as a foundation for further studies on the development and function of the catshark retina. Moreover, integration of our atlas with data from other species will allow for a better understanding of vertebrate retinal evolution.
Project description:Gene expression profiling of pooled late stage embryos from Leucoraja erinacea, Scyliorhinus canicula and Callorhinchus milii show that HOXC cluster genes are not expressed in the two elasmobranch fishes, L. erinacea and S. canicula. This finding supports the observations that these genes are not found in whole genome shotgun sequencing of L. erinacea or genomic clones from S. canicula.
