@article {132, title = {Embryonically expressed GABA and glutamate drive electrical activity regulating neurotransmitter specification.}, journal = {J Neurosci}, volume = {28}, year = {2008}, month = {2008 Apr 30}, pages = {4777-84}, abstract = {

Neurotransmitter signaling in the mature nervous system is well understood, but the functions of transmitters in the immature nervous system are less clear. Although transmitters released during embryogenesis regulate neuronal proliferation and migration, little is known about their role in regulating early neuronal differentiation. Here, we show that GABA and glutamate drive calcium-dependent embryonic electrical activity that regulates transmitter specification. The number of neurons expressing different transmitters changes when GABA or glutamate signaling is blocked chronically, either using morpholinos to knock down transmitter-synthetic enzymes or applying pharmacological receptor antagonists during a sensitive period of development. We find that calcium spikes are triggered by metabotropic GABA and glutamate receptors, which engage protein kinases A and C. The results reveal a novel role for embryonically expressed neurotransmitters.

}, keywords = {Animals, Antigens, CD57, Calcium, Choline O-Acetyltransferase, Embryo, Nonmammalian, Enzyme Inhibitors, Excitatory Amino Acid Antagonists, GABA Antagonists, gamma-Aminobutyric Acid, Gene Expression Regulation, Developmental, Glutamate Decarboxylase, Glutamic Acid, Health Services Research, Larva, Morpholines, Neurons, Phosphoserine, Receptors, GABA, Receptors, Glutamate, Synapses, Vesicular Glutamate Transport Proteins, Xenopus}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.4873-07.2008}, author = {Root, Cory M and Vel{\'a}zquez-Ulloa, Norma A and Monsalve, Gabriela C and Minakova, Elena and Spitzer, Nicholas C} } @article {133, title = {Illumination controls differentiation of dopamine neurons regulating behaviour.}, journal = {Nature}, volume = {456}, year = {2008}, month = {2008 Nov 13}, pages = {195-201}, abstract = {

Specification of the appropriate neurotransmitter is a crucial step in neuronal differentiation because it enables signalling among populations of neurons. Experimental manipulations demonstrate that both autonomous and activity-dependent genetic programs contribute to this process during development, but whether natural environmental stimuli specify transmitter expression in a neuronal population is unknown. We investigated neurons of the ventral suprachiasmatic nucleus that regulate neuroendocrine pituitary function in response to light in teleosts, amphibia and primates. Here we show that altering light exposure, which changes the sensory input to the circuit controlling adaptation of skin pigmentation to background, changes the number of neurons expressing dopamine in larvae of the amphibian Xenopus laevis in a circuit-specific and activity-dependent manner. Neurons newly expressing dopamine then regulate changes in camouflage colouration in response to illumination. Thus, physiological activity alters the numbers of behaviourally relevant amine-transmitter-expressing neurons in the brain at postembryonic stages of development. The results may be pertinent to changes in cognitive states that are regulated by biogenic amines.

}, keywords = {Animals, Behavior, Animal, Cell Count, Cell Differentiation, Chelating Agents, Dopamine, Egtazic Acid, Gene Expression Regulation, Developmental, Larva, Light, Lighting, Melanotrophs, Neurons, Neuropeptide Y, Photic Stimulation, Skin Pigmentation, Sodium Channel Blockers, Suprachiasmatic Nucleus, Tetrodotoxin, Xenopus laevis}, issn = {1476-4687}, doi = {10.1038/nature07569}, author = {Dulcis, Davide and Spitzer, Nicholas C} } @article {153, title = {Natural behavior polymorphism due to a cGMP-dependent protein kinase of Drosophila.}, journal = {Science}, volume = {277}, year = {1997}, month = {1997 Aug 8}, pages = {834-6}, abstract = {

Naturally occuring polymorphisms in behavior are difficult to map genetically and thus are refractory to molecular characterization. An exception is the foraging gene (for), a gene that has two naturally occurring variants in Drosophila melanogaster food-search behavior: rover and sitter. Molecular mapping placed for mutations in the dg2 gene, which encodes a cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG). Rovers had higher PKG activity than sitters, and transgenic sitters expressing a dg2 complementary DNA from rover showed transformation of behavior to rover. Thus, PKG levels affected food-search behavior, and natural variation in PKG activity accounted for a behavioral polymorphism.

}, keywords = {Animals, Animals, Genetically Modified, Cyclic GMP, Cyclic GMP-Dependent Protein Kinases, Drosophila melanogaster, Feeding Behavior, Genes, Insect, Larva, Phenotype, Polymorphism, Genetic, Signal Transduction}, issn = {0036-8075}, author = {Osborne, K A and Robichon, A and Burgess, E and Butland, S and Shaw, R A and Coulthard, A and Pereira, H S and Greenspan, R J and Sokolowski, M B} }