A fluorescence assay for phenylalanine transfer RNA.
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Animals↗
Biomedical subjects
D Yoshikami
Publications and source records attributed to D Yoshikami.
A venom peptide with a novel presynaptic blocking action.
The venom of the fish-eating marine mollusc, Conus geographus, contains several neurotoxic peptides having different targets. A novel peptide has recently been isolated from the venom of C. geographus by Drs B. M. Olivera and W. R. Gray and colleagues in our department (in preparation). We report here that this peptide, designated omega CgTX (omega C. geographus toxin), irreversibly blocks nerve stimulus-evoked release of transmitter at the frog skeletal neuromuscular junction. Experiments indicate that the toxin acts by preventing action potential. Consistent with this is the demonstration that omega CgTX also irreversibly attenuates the Ca2+ component of the action potential in dorsal root ganglion (DRG) neurones from embryonic chick. omega CgTX thus provides a unique and potentially powerful probe for exploring the presynaptic terminal.
Action Potentials↗
Staining of living presynaptic nerve terminals with selective fluorescent dyes.
Johnson et al. have recently shown that several positively charged, membrane-permeant fluorescent dyes can serve as vital stains for mitochondria in cultured cells. We report here that presynaptic nerve terminals, which are characteristically rich in mitochondria, can also be vitally stained with such dyes, and that this staining offers a resolution of structural detail not available with previous methods for visualizing terminals in living tissues. The dyes have provided excellent, highly detailed fluorescence images of presynaptic motor nerve terminals at neuromuscular junctions in conventional live tissue preparations from mouse, frog and Drosophila. In addition, when tested at the frog neuromuscular junction, at least one of the dyes permitted visualization of terminals with little, if any, effect on synaptic transmission. Moreover, we have found that by using the dyes it is now also possible to see motor nerve terminals in situ in live animals.
Action Potentials↗