Meeting Abstract

33.6  Friday, Jan. 4  On the Origins of Glutamatergic Signaling: Insights from the ctenophore genome (Pleurobrachia bachei ) SWORE, J.J.*; KOHN, A.B.; KOCOT, K.M.; SWALLA, B.J.; NOREKIAN, T; MOROZ , L.L.; Univ of Florida; Univ of Florida; Auburn Univ; Univ of Washington; Univ of Florida; Univ of Florida jjswore@students.nwc.edu

Ctenophores are extant representatives of one of the earliest animal lineages. Yet, as pelagic predators, they developed remarkable behavioral complexity with ‘true’ neurons and muscles. Here, we performed a genome-wide survey of neurotransmitters in the ctenophore Pleurobrachia bachei focusing on the characterization of glutamate (Glu) mediated signaling. Specifically, we identified and characterized the molecular organization and expression of 14 ionotropic Glu receptors (iGluR), and associated components of Glu synthesis and uptake. In Pleurobrachia, we discovered an unprecedented molecular diversity of Glu signaling; a diversity that far exceeds the situation observed in other animals including humans. There is also an extremely unusual genomic organization of many iGluRs. All cloned receptors showed remarkable cell-type specific expression both in development and in adults, but only a small subset of receptors is associated with neuronal-type elements, suggesting pre-neuronal origins of Glu-mediated transmission. In summary, we revealed the presence of well-developed Glu signaling in Ctenophores. However, this type of signaling is substantially different from other animals and can be explained in terms of extensive parallel evolution. On the other hand, Ctenophores might preserve one of the earliest designs of neural organization among animals, with a number of unique innovations absent or lost in other animal lineages.