John A. Couch

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The teleost liver is one of the most sensitive organs to show alteration in biochemistry, physiology and structure following exposure to various types of environmental pollutants. Despite the importance of this organ to environmental toxicology and to ecotoxicology where biomarkers of exposure and of deleterious effect are found, the architectural pattern(More)
The occurrence of high concentrations of a PCB (Aroclor 1254) in the Pensacola estuary prompted field and laboratory studies by the Gulf Breeze Environmental Research Laboratory (EPA). Monitoring of the estuary indicates the chemical is present in all components--particularly in sediments and fishes. Residues appear to be diminishing in sediments. Toxicity(More)
A large group of shrimp, 23.3% of which had light patent Baculovirus infections, was divided equally into two groups. One group was exposed to the chemical stressor Aroclor 1254 (a polychlorinated biphenyl) at 0.7 ppb for 35 days in flowing seawater. The other group was maintained as a control group in flowing seawater. Viral prevalence in exposed shrimp(More)
Groups of estuarine sheepshead minnows (Cyprinodon variegatus) were exposed to approximately 57 mg N-nitrosodiethylamine [(DENA) CAS: 55-18-5]/liter for 5-6 weeks. Exposure was stopped and the fish were then transferred to clean, flowing seawater. Induced liver lesions were studied in periodic samples of fish taken during the next 140 weeks of holding.(More)
The host range of the insect virus Autographa californica nuclear polyhedrosis virus (AcMNPV) was examined. AcMNPV could not initiate a productive infection in frog, turtle, trout, or codling moth cell lines. After exposure to AcMNPV, neither viral DNA nor RNA synthesis could be detected in these cell lines as assayed by nucleic acid probe hybridization.(More)
Spongiosis hepatis (SH), first reported as a distinct lesion associated with certain forms of hepatic neoplasia in rats, has also been induced with chemicals, in a predictable fashion, in small teleost fishes being studied as carcinogenesis research models. The sheepshead minnow (Cyprinodon variegatus), exposed to N-nitrosodiethylamine (DENA) in sea water,(More)
Scoliosis in fish is caused by several diverse agents that possibly act on the central nervous system, neuromuscular junctions, or ionic metabolism. The organochlorine pesticide Kepone induces scoliosis in the sheepshead minnow. Some effects associated with Kepone-induced scoliosis in these fish are disruption of myotomal patterns, inter- and intramuscular(More)
An unusually high, unprecedented prevalence of cardiac hemangioendotheliomata, including hemangiomas, hemangioendotheliomas, and hemangioendotheliosarcomas, was found in a laboratory cohort of the small, teleost fish Rivulus marmoratus. The neoplasms occurred in 51 of 204 fish (25%) used in a carcinogenicity study of butylated hydroxyanisole fed in a(More)