ABSTRACT
Gustducin is a transducin-like G protein (guanine nucleotide-binding protein) that is expressed in taste bud cells. Gustducin is believed to be involved in bitter and possibly sweet taste transduction. In the present study, we demonstrate that a subset of type II cells displays immunoreactivity to antisera directed against gustducin in taste buds of rat circumvallate papilla. Immunogold particles are present both in the microvilli and cytoplasm of the immunoreactive cells. Quantitative analysis of the data suggests that the number of colloidal gold particles (P<0.001) and nanogold particles (P<0.01) in the immunoreactive type II cells are much greater than in type I cells. There are also approximately 2.5 times (P<0.05) as many colloidal gold particles associated with the microvilli versus the cytoplasm in the immunoreactive type II cells. The ultrastructural distribution of gustducin immunoreactivity is consistent with its proposed role in the initial events of sensory transduction by gustatory receptor cells.
Subject(s)
Microvilli/chemistry , Rats, Sprague-Dawley/physiology , Taste Buds/chemistry , Transducin/analysis , Animals , Antibodies , Cytoplasm/chemistry , Female , Fluorescent Antibody Technique , GTP-Binding Proteins/physiology , Male , Microscopy, Confocal , Microscopy, Immunoelectron , Microvilli/immunology , Rats , Signal Transduction/physiology , Taste Buds/physiology , Taste Buds/ultrastructure , Transducin/immunologyABSTRACT
SNAP-25 is a 25 kDa protein believed to be involved in the processes of membrane fusion and exocytosis associated with neurotransmitter release. In the present study we present evidence that SNAP-25-like immunoreactivity can be used as a marker for taste cells with synapses in rat circumvallate papillae. SNAP-25 immunoreactivity is present in most intragemmal nerve processes and a small subset of taste cells. Intense immunoreactivity is associated with the nerve plexus located below the base of the taste bud. Of a total of 87 taste cells with synapses onto nerve processes, 80 of the presynaptic taste cells had SNAP-25 immunoreactivity. The association of SNAP-25 immunoreactivity with taste cells possessing synapses suggests that these cells may be gustatory receptor cells. Because this SNAP-25 antibody can label taste cells with synapses, it may also serve as a useful tool for future studies correlating structure with function in the taste bud.
Subject(s)
Membrane Proteins , Nerve Tissue Proteins/metabolism , Neurons, Afferent/ultrastructure , Synapses/ultrastructure , Taste Buds/ultrastructure , Animals , Female , Male , Neurons, Afferent/metabolism , Rats , Rats, Sprague-Dawley , Synapses/metabolism , Synaptosomal-Associated Protein 25 , Taste Buds/metabolismABSTRACT
Vacuum drying, under appropriate conditions, diminishes the warping and buckling of epoxy semithin sections and enhances visualization with light microscopy. Treatment of sections with chloroform or variations in the drying times or temperatures did not reduce wrinkling.
