TUBLITZ, NJ; University of Oregon: Mechanisms underlying peptide mediated neuroplasticity: A spineless approach in moths, flies and cephalopods.

This talk discusses 4 separate mechanisms underlying peptide mediated neuroplasticity that have evolved in several invertebrates. The first is at the cellular level in the moth Manduca sexta. Manduca has a set of larval neurons that express a subset of cardioacceleratory peptides (CAPs). During metamorphosis these neurons undergo a complete transformation, changing their physiological, biochemical and morphological properties. This cellular alteration is hormonally-triggered by the insect steroid hormone 20-OH ecdysone. CAP expression in other neurons is also significantly altered during metamorphosis. The second example of peptide mediated plasticity is at the biochemical level and involves evolutionary variation in CAP signaling pathways in three different insect species. With others, we have demonstrated that the neuropeptide CAP2b causes differential effects on the Malpighian tubules in the fly Drosophila melanogaster, the bloodsucking bug Rhodnius prolixis and the moth Manduca sexta. This talk will focus on the species-specific differences in the biochemical pathways causing this functional diversity. A third example of peptide-mediated plasticity is at the developmental level.in Drosophila. Two CAPs, CCAP and CAP2b, are expressed in the mesodermally-derived midline mesoderm cells (MMCs) of Drosophila. The MMCs extend a neuronal-like process, express neuronal markers, have voltage-dependent channels, and contain bioactive CAPs. These data suggest that the MMCs act as neurosecretory cells despite their non-neural origins. The final example of peptide mediated plasticity is at the system level, centering on the control of body patterning behavior in cephalopods. Several basic principles will be discussed to set the stage for the following talk by Dr. Poh Kheng Loi on the neural regulation of body patterning behavior in cephalopods.