Turbellarian taxonomic database

Abstract / Notes

"The origin of bilateral symmetry, a major transition in animal evolution, coincided with the evolution of
organized nervous systems that show regionalization along major body axes. Studies of Xenacoelomorpha, the
likely outgroup lineage to all other animals with bilateral symmetry, can inform the evolutionary history of
animal nervous systems. Here, we characterized the neural anatomy of the acoelHofstenia miamia. Our analysis
of transcriptomic data uncovered orthologues of enzymes for all major neurotransmitter synthesis pathways.
Expression patterns of these enzymes revealed the presence of a nerve net and an anterior condensation of
neural cells. The anterior condensation was layered, containing several cell types with distinct molecular
identities organized in spatially distinct territories. Using these anterior cell types and structures as
landmarks, we obtained a detailed timeline for regeneration of theH.miamianervous system, showing that the
anterior condensation is restored by eight days after amputation. Our work detailing neural anatomy
inH.miamiawill enable mechanistic studies of neural cell type diversity and regeneration and provide insight
into the evolution of these processes."