Research Associate

My background is in biophysics. My Ph.D. work at Ohio State University involved the use of circular dichroism spectroscopy and various biochemical modifications to study the mechanism by which changes in conformation of the membrane protein, bacteriorhodopsin, could allow it to pump protons out of the cell. My studies convinced me that the rigidity of the lipid membrane surrounding the protein was important in determining whether the protein could undergo the required conformational changes.

I subsequently did a postdoc in a physical chemistry lab at the University of Arizona in which I investigated the effect of membrane lipid headgroup and acyl chain composition on the function of another membrane protein, bovine rhodopsin. My work with rhodopsin convinced me that many membrane proteins depend on a complex mixture of lipid headgroup size and charge, and on acyl chain length and unsaturation, for normal functioning. Basically, membrane lipid composition will determine the degree to which the membrane resists or assists the protein in undergoing necessary conformational changes. Furthermore, this explains how cell signaling can be accomplished by phospholipases, which release fatty acids to a cell surface, thereby altering the membrane's properties and subsequently a protein's state. This appeared to be very important in cells of the nervous system, so I joined the ARLDN in order to improve my understanding of that system. My focus has shifted from biophysical interactions in the membrane to questions of development of brain structure, particularly axon guidance. My current efforts (spanning the Hildebrand, Tolbert, and Nighorn labs) include studies of the role of nitric oxide synthase in formation of the brain during metamorphosis in Manduca sexta (Fig 1), as well as the role played by downstream effectors of NO including soluble guanylyl cyclase (Fig 2) and NO-induced acylation, glycosylation, nitrosylation, and ADP-ribosylation of proteins. In particular, I am studying the mechanisms by which NO can affect cell migration and growth cone outgrowth by using drugs which block particular biochemical pathways known to be modulated by NO.

Other work currently underway involves the biochemical and molecular biological characterization of proteins (and possibly lipids) responsible for the sexually dimorphic architecture of the primary olfactory centers of the Manduca brain. I am working toward isolating proteins/lipids unique to the male pheromone-responsive olfactory receptor cells based on attached carbohydrate residues (Fig 3).

Selected Publications
Gibson NJ, Nighorn A (2000) Expression of nitric oxide synthase and soluble guanylyl cyclase in the developing olfactory system of Manduca sexta. J Comp Neurol, in press.

Nighorn A, Gibson NJ, Rivers D,Hildebrand JG, Morton DB (1998) The nitric oxide-cGMP pathway may mediate communication between sensory afferents and projection neurons in the antennal lobe of Manduca sexta. J Neurosci 18(18), 7244-7255.

Gibson NJ, Brown MF (1992) Lipid headgroup and acyl chain composition modulate the MI_MII equilibrium of rhodopsin in recombinant membranes. Biochemistry 32:2438-2454.

Brown MF, Gibson NJ (1992) Biological function of docosahexaenoic acid in the retinal rod disk membrane. In: Sinclair A, Gibson R (eds) Proc Third Internat Cong Essential Fatty Acids & Eicosanoids, pp 134-138.

Gibson NJ, Brown MF (1991) Membrane lipid influences on the energetics of the MI and MII conformational states of rhodopsin probed by flash photolysis. Photochem Photobiol 54:985-992.

Gibson NJ, Cassim JY (1989) Evidence for an alpha II-type helical conformation for bacteriorhodopsin in the purple membrane. Biochemistry 28: 2134-2139.

Gibson NJ, Cassim JY (1989) Nature of forces stabilizing the transmembrane protein bacteriorhodopsin in purple membrane. Biophys J 56:769-780.