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Full-Text Articles in Physical Sciences and Mathematics
Toxic Responses Of The Fish Nervous System, Steven P. Bradbury, Richard W. Carlson, Tala R. Henry, Stephanie Padilla, John Cowden
Toxic Responses Of The Fish Nervous System, Steven P. Bradbury, Richard W. Carlson, Tala R. Henry, Stephanie Padilla, John Cowden
Steven P. Bradbury
Few of the approximately 70,000 chemicals on the Toxic Substances Control Act inventory or the 1000 to 1600 new chemicals introduced each year in the United States have been tested for neurotoxicity to support risk assessments (NRC, 1992), even though it is estimated that 5 to 10% of them are likely to be neurotoxic. Neurotoxicity has been defined as adverse effects of physical, biological, or chemical agents on the structure or function of the nervous system in developing or adult organisms (Philbert et al., 2000). From a human health risk assessment perspective, the potential for neurotoxic effects associated with synthetic …
Neurological Effects On Startle Response And Escape From Predation By Medaka Exposed To Organic Chemicals, Steven P. Bradbury, Richard W. Carlson, Robert A. Drummond, Dean E. Hammermeister
Neurological Effects On Startle Response And Escape From Predation By Medaka Exposed To Organic Chemicals, Steven P. Bradbury, Richard W. Carlson, Robert A. Drummond, Dean E. Hammermeister
Steven P. Bradbury
Simultaneous electrophysiological and behavioral studies were performed on 21–32 day old juvenile medaka (Oryzias latipes) exposed at sublethal concentrations to organic chemicals representing various modes of action. Non-invasive recordings were made of the electrical impulses generated within giant neuronal Mauthner cells, associated interneurons and motoneurons, and axial musculature, all of which initiate the startle or ‘escape’ response in fish. Timing in ms between these electrical sequelae was measured for each fish before and after 24 and 48 h exposure to a chemical. Carbaryl and phenol affected Mauthner cell to motoneuron transmission while chlorpyrifos, carbaryl, phenol and 2,4-dinitrophenol (DNP) showed neuromuscular …
A Non-Invasive Neurotoxicity Assay Using Larval Medaka, Steven P. Bradbury, Dave Featherstone, Charles D. Drewes, Joel R. Coats
A Non-Invasive Neurotoxicity Assay Using Larval Medaka, Steven P. Bradbury, Dave Featherstone, Charles D. Drewes, Joel R. Coats
Steven P. Bradbury
We present a method for non-invasive electrophysiological analysis of rapid escape responses in intact, freely behaving larval medaka (Oryzias latipes) before and after short-term exposure to environmental toxicants. Recordings are obtained as a larval medaka swims in a small chamber of water above pairs of recording electrodes etched onto a printed circuit board. When the chamber is briefly vibrated by a sinusoidal pulse from a speaker attached to the grid, a stereotyped Mauthner cell-initiated escape response is evoked. The following parameters were quantified from recordings: 1) Mauthner axon conduction velocity, 2) delay between Mauthner axon spike and motoneuron spike in …