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Nathan Tublitz

Professor, Department of Biology
B.A., 1974, Reed College
Ph.D., 1983, University of Washington

Research Interests

Neural mechanisms underlying behavior: a) neurobiology of peptidergic neurons in insects with particular emphasis on their physiology, mode of action, biochemistry, development, and gene expression; b) neuronal regulation of body patterning behavior in cephalopod mollusks.

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The long term goal of my research is to elucidate the neural mechanisms underlying behavior. My specific focus has been on illuminating the role of neuropeptides in mediating behavioral plasticity, which in this context is defined as the ability of the nervous system to vary the performance of a specific behavior to meet changing internal or external conditions. My colleagues and I have been investigating this issue in three different invertebrate preparations, the moth Manduca sexta, the fly Drosophila melanogaster, and the cuttlefish Sepia officinalis, each of which has a unique set of exploitable advantages that we have used in reductionistic studies on behavioral plasticity.

Our studies on the physiological and behavioral implications of neuropeptide action in insects have focused on the Cardioacceleratory Peptides (CAPs), a group of myomodulatory peptides employed repeatedly throughout the animal's life cycle to modulate distinct behaviors at each stage. CAP flexibility is highlighted by the fact that the CAPs have four different stage-specific functions, affect at least two distinct targets, are differentially expressed in larvae and adults, and act either as neurohormones or local neuromodulators, depending upon the circumstances. Our efforts in Manduca have centered on identifying new CAP targets, elucidating CAP structures and genes, and studying the mechanisms responsible for the plasticity of CAP-containing neurons, which undergo profound changes in morphology, biochemistry, and physiology. Our work in Drosophila deals with the identification and expression of CAP coding genes and with understanding the development of the CAP cells in flies. We have also studied CAP function in several other insects including the blood sucking bug Rhodnius and the fly Calliphora.

Although many important new insights have been gleaned about the neural regulation of simple behaviors using a host of invertebrate preparations including Manduca and Drosophila, it is clear that additional principles are necessary to explain more complex behaviors routinely exhibited in higher invertebrates and vertebrates. To study behaviors that are both more complicated and more plastic, we have also been studying cephalopod molluscs, the most behaviorally sophisticated taxa among invertebrates. Our focus has been on body patterning behavior, the most plastic of known invertebrate behaviors. Cephalopods, especially cuttlefish, produce numerous body patterns noted for their intricacy and speed of formation. Unique to cephalopods, body patterning behavior involves activation of a peripheral chromatophore system that is under neuromuscular control. The complex behavior of individual chromatophores is mediated by a specific set of muscles, the chromatophore muscles, that receive direct CNS innervation. We have identified several neuronal mechanisms that contribute to the generation of transient and sustained body patterns in cuttlefish and other cephalopods. Our long-term goal with this system is to understand the neuronal mechanisms underlying the generation and modulation of these intricate patterns.

Representative Publications