Fred M. McCorkle

Light and electron microscope structure of secretory cells in the medulla of bursal follicles of normal and cyclophosphamide treated chickens.

Abstract A specialized cell was identified in the medulla of bursal follicles referred to as a secretory cell (SC). The SC, present at all ages was concentrated in the vicinity of the corticomedullary border. Each secretory cell near the nucleus usually possessed a single long process containing 3–10 dark granules surrounded by a membrane. The SC increased in number and apparent secretory activity after cyclophosphamide treatment. All medullary pores were filled with a darkly staining substance, apparently secreted by the SC.

A biphasic graft vs host response in aging chickens

Abstract The graft vs host (GvH) and phytohemagglutinin (PHA) wattle responses were the parameters chosen to evaluate cell-mediated immunity in aging chickens. At 6 and 24 months of age female spleen cells were significantly more effective in eliciting a GvH response than spleen cells from 1-, 2-, 12-, and 18-month-old females. The biphasic GvH response produced by female spleen cells was not observed for male spleens. On the other hand, peripheral blood lymphocytes from both males and females exhibited a single peak, 3–6 months, in their ability to produce a GvH response. The thymic-dependent PHA wattle response of males was significantly greatest at 1 month of age and declined thereafter. Once again the females exhibited a different pattern than the males. At 1 month of age the females wattle response was significantly greater than at 3 months, but rather than declining with age the wattles of aging females responded like 1-month-old females. Several mechanisms are offered to explain the apparent age-related regression-regeneration of cell-mediated immunity in the female.

Acute toxicities of selected herbicides to fingerling channel catfish,Ictalurus punctatus

SummaryA scan of the acute toxicities of eighteen common herbicides to one-year-old channel catfish (Ictalurus punctatus) was conducted. Herbicides causing less than 10% mortality in 48 hr at 10 ppm were: alanap, chloramben, 2,4-D acid, 2,4-D dimethyl amine salt, dalapon, diuron, DSMA, EPTC, fluometuron, metribuzin, monuron, MSMA, nitralin and 2,4,5-T. The 96-hr LC50 values in ppb for four herbicides found toxic were: propanil, 3796; trifluralin, 417; bensulide, 379; and DNBP, 118. The toxicity of Dyanap®, a mixture of DNBP and alanap, was lower than that of DNBP; there was no apparent synergism between DNBP and alanap in the mixture.

Enzyme activities following chronic exposure to crude oil in a simulated ecosystem: I. American oysters and brown shrimp

Abstract Enzyme activities were investigated in whole-body homogenates from oysters and hepatopancreas homogenates from shrimp which had been exposed to crude oil for 8 months in a simulated estuarine ecosystem. Enzymes assayed included acetylcholinesterase, alkaline phosphatase, β-glucuronidase, glutamic-pyruvic transaminase, lactic dehydrogenase, and malic dehydrogenase. Few seasonal trends in enzyme activity were observed in either species. Several alterations in enzyme activity were noted in oil-treated shrimp and oysters 6–8 months following the oil spill when the animals were stressed and may reflect physiological changes in animals which are severely stressed. However, few chronic alterations in enzyme activity were observed which could be attributed to the oil spill.

Variation in enzyme activities of the American oyster (Crassostrea virginica) relative to size and season

Abstract 1. 1. The specific activities and subcellular distribution of eleven enzymes were determined in whole body homogenates of the American oyster, Crassostrea virginica . 2. 2. The activities of lactic dehydrogenase, cytochrome oxidase, and acid phosphatase were inversely proportional to organism weight. 3. 3. Seasonal fluctuations were observed for malic dehydrogenase, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, acetylcholinesterase, alkaline phosphatase and acid phosphatase.

Enzyme activities following chronic exposure to crude oil in a simulated ecosystem. II. Striped mullet.

Abstract Enzyme activities were investigated in brain, gill, liver, and muscle homogenates from striped mullet which had been exposed to crude oil for 10 months in a simulated estuarine ecosystem. Enzymes assayed included acetylcholinesterase, alkaline phosphatase, β-glucuronidase, glutamic-pyruvic transaminase, lactic dehydrogenase, and malic dehydrogenase. Few seasonal trends in enzyme activities were observed. Alterations in some enzyme activities, particularly acetylcholinesterase, β-glucuronidase, and malic dehydrogenase, may have reflected physiological changes in the mullet resulting from stress. In general, there were few chronic alterations in mullet enzyme activities resulting from the oil spill.

Seasonal effects on selected tissue enzymes in channel catfish, Ictalurus punctatus

Abstract 1. 1. Specific activities of lactic and malic dehydrogenases and glutamic oxaloacetic and glutamic pyruvic transaminases in brain, gill, liver and muscle of young channel catfish were 2–3-fold higher during the winter (non-growing season) than in the summer (growing season). 2. 2. These differences are felt to reflect higher activities of these enzymes involved in maintenance during the non-growing season and lower enzyme activities during the growing season because of a shift in metabolism. 3. 3. Protein concentrations were similar in both seasons except for an increase in muscle protein during the growing season. This difference could be associated with the rapid growth phase.

Tolerance of low oxygen stress in insecticide-resistant and susceptible populations of mosquitofish (Gambusiaaffinis)

Abstract The tolerance of low oxygen stress in insecticide-resistant and susceptible populations of mosquitofish ( Gambusia affinis ) was investigated. Dissolved oxygen was reduced chemically with formaldehyde and sodium sulfite treatment. Available oxygen was reduced physically through barriers, both by preventing oxygen exchange at the air-water interface and by preventing the fish from contacting the surface of the water. In all cases, the tolerance to low oxygen stress was reduced in the insecticide-resistant population compared to the susceptible population. The results indicate that although tolerance of pesticides in the resistant population has been dramatically increased by environmental selective pressures, tolerance to other stresses has not been concomitantly increased.

Tissue enzyme activities following exposure to dietary mirex in the channel catfish, ictalurus punctatus

Abstract Young channel catfish Ictalurus punctatus were exposed to 1, 100, 200 and 400 ppm dietary mirex. Specific activities of lactic dehydrogenase, malic dehydrogenase, glutamate pyruvate transaminase and glutamate oxaloacetate transaminase were determined in brain, gill, liver and muscle at one, two, three and four weeks. Few changes in enzyme sppecific activities were found which were attributed to mirex exposure. It appears that mirex, even at high dietary exposure levels, is relatively innocuous to these enzyme activities.