The nitric oxide-cGMP pathway may mediate communication between sensory afferents and projection neurons in the antennal lobe of Manduca sexta.
The nitric oxide (NO)-cGMP signaling system is thought to play important roles in the function of the olfactory system in both vertebrates and invertebrates. One way of studying the role of NO in the nervous system is to study the distribution and properties of NO synthase (NOS), as well as the soluble guanylyl cyclases (sGCs), which are the best characterized targets of NO. We study NOS and sGC in the relatively simple and well characterized insect olfactory system of the hawkmoth, Manduca sexta. We have cloned Manduca sexta nitric oxide synthase (MsNOS) and two sGCs (MsGCalpha1 and MsGCbeta1), characterized their basic biochemical properties, and studied their expression in the olfactory system. The sequences of the Manduca genes are highly similar to their mammalian homologs and show similar biochemical properties when expressed in COS-7 cells. In particular, we find that MsGC functions as an obligate heterodimer that is stimulated significantly by NO. We also find that MsNOS has a Ca2+-sensitive NO-producing activity similar to that of mammalian neuronal NOS. Northern and in situ hybridization analyses show that MsNOS and the MsGCs are expressed in a complementary pattern, with MsNOS expressed at high levels in the antennae and the MsGCs expressed at high levels in a subset of antennal lobe neurons. The expression patterns of these genes suggest that the NO-sGC signaling system may play a role in mediating communication between olfactory receptor neurons and projection neurons in the glomeruli of the antennal lobe.
Nighorn
A
A
Arizona Research Laboratories, Division of Neurobiology, University of Arizona, Tucson, Arizona 85721, USA.
Gibson
N J
NJ
Rivers
D M
DM
Hildebrand
J G
JG
Morton
D B
DB
D000825:Animal Structures / Q000294:innervation; D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D003001:Cloning, Molecular; D006152:Cyclic GMP / Q000378:metabolism*; D019281:Dimerization; D017952:Ganglia, Invertebrate / Q000737:chemistry / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D006162:Guanylate Cyclase / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008322:Mammals; D018402:Manduca; D008969:Molecular Sequence Data; D009475:Neurons, Afferent / Q000166:cytology* / Q000201:enzymology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012903:Smell / Q000502:physiology
D007527:Isoenzymes; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D006162:Guanylate Cyclase; D006152:Cyclic GMP