From, Department of Neuroscience and Developmental Biology, Vienna University, Austria

Will give a seminar entitled:

Tracing the developmental and evolutionary origin of neurosecretory and muscle cells in the sea anemone Nematostella vectensis

Abstract:

The sea anemone Nematostella vectensis is a member of the cnidarians, which arose about 600-700 Million years ago and is the sister group to the Bilateria. Therefore the comparative study of cnidarians may offer important insights into the evolution of bilaterian traits and body plans. Cnidarians consist of only two cell layers, which have been commonly termed endoderm and ectoderm, even though their homology to the bilaterian germ layers has been questioned. They do possess a relatively simple nervous system and dedicated muscle cells in both layers. We used single cell transcriptomics, validated by in situ hybridisations and transgenics to identify and localize cell populations throughout development. We focused on the neurosecretory complement (i.e. neurons, cnidocytes and gland cells) and delineated their developmental origin from putative multipotent precursors. Transgenic lines validated several developmental regulators conserved in bilaterians. We also delineated the muscle complement in the polyps and found 4 distinct muscle cell types. Physiological evidence suggests the existence of fast and slow contracting muscles, which differ by sets of paralogous structural protein genes. Notably, only one muscle, the tentacle retractor muscle, is of ectodermal origin and determined by one specific bHLH transcription factor. I will discuss these results in the light of muscle and neurosecretory lineage differentiation in bilaterians.