Meeting Abstract

P3.191  Monday, Jan. 6 15:30  Quest for Neurogenic Genes in Ctenophores KO, J.H.*; KOHN, A.B.; MOROZ, L.L.; Massachusetts Institute of Technology, Cambridge and Whitney Laboratory for Marine Bioscience, St. Augustine, FL; Whitney Laboratory for Marine Bioscience, St. Augustine, FL; Whitney Laboratory for Marine Bioscience, St. Augustine, FL kojulieh@mit.edu

The ctenophore Pleurobrachia bachei is a basal metazoan with a relatively simple nervous system that consists of subepidermal and mesogleal nets and the aboral organ, an analog of an elementary brain. The initial analysis of the recently sequenced Pleurobrachia genome suggests an enormous degree of parallel evolution of neural organization, and no pan-neuronal genes have yet been identified in ctenophores. The aim of this study was to find neuronal markers in P. bachei. Specifically, we cloned and, by in situ hybridization, characterized the expression of two candidate genes, Neuroglobin and Musashi3. In bilaterians, both are conservative neural genes – Neuroglobin is most likely involved in oxygen transport in the brain, and Musashi3 is a neural RNA binding protein. We find that Neuroglobin is expressed in the comb plates and individual, unknown cells around the comb plates. Musashi3 is expressed in the aboral organ, polar fields, and combs; however, its expression is not localized in recognized neural type cells in the aboral organ and polar fields. The results for both genes suggest that unlike in other metazoans, Neuroglobin and Musashi3 are not expressed in neurons. They also provide additional support for two related hypotheses – one, that ctenophores are the most basal branching metazoans; and two, the ctenophore nervous systems might have evolved independently from the rest of animals.