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Donald R. Buhler

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1. Fish liver microsomal systems have been found to catalyze the hydroxylation of aniline and acetanilide, the N-demethylation of aminopyrine and the O-dealkylation of phenacetin.2. These systems are similar to the corresponding mammalian enzymes and they may be considered to be mixed function oxidase since they require NADPH and oxygen. An absolute requirement for oxygen, however, was difficult to demonstrate for the hepatic phenacetin cleavage system from fish.3. Microsomal drug metabolizing systems from fish have temperature optima which are considerably lower than those of corresponding mammalian systems
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The specific activity of liver glucose 6-phosphate dehydrogenase in yearling rainbow trout remained unchanged when the fish were starved for periods as long as 8 weeks and when starved animals were fed diets of various compositions. Injection of insulin concurrently with refeeding also failed to alter the specific activity of the enzyme in trout. The absence of a dietary or insulin influence on the teleost enzyme system is to be contrasted with studies in mammals in which the activity of hepatic glucose 6-P dehydrogenase was markedly stimulated after refeeding starved animals or injection of insulin.Ingestion of the pesticide DDT by juvenile coho salmon or adult rainbow trout also had no effect on the specific activity...
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Technical and p,p′-DDT was incorporated into test diets and fed to juvenile chinook and coho salmon for periods as long as 95 days. Pure p,p′-DDT was slightly more toxic to young salmon than was the technical DDT mixture. Chinook salmon appeared to be 2–3 times more sensitive to a given concentration of DDT in the diet than were coho salmon. The size of the fish greatly influenced toxicity, smaller younger fish being more susceptible to a given diet than larger older fish. The dose of DDT accumulated within the median survival time ranged from 27–73 mg/kg for chinook salmon and from 56–72 mg/kg for coho salmon. The extrapolated 90-dose LD50 (Hayes, 1967) for young chinook and coho salmon were 0.0275 and 0.064 mg/kg/day,...
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