Thomas L. Meade

The influence of ammonia on the oxygen delivery system of coho salmon hemoglobin

Abstract 1. 1. The influence of ammonia on respiration has long been recognized, yet no definitive conclusions have been reached. 2. 2. The information provided suggests a mechanism brought about by prolonged exposure to elevated external levels of ammonia in an aqueous environment. 3. 3. Initial stimulation of glycolysis causes a progressive acidemia which, sequentially, has a negative effect on the oxygen transport function of hemoglobin. 4. 4. Spectrophotometric data of hemoglobin solutions from coho salmon yearlings subjected to increased environmental ammonia concentrations revealed a progressive transformation of the characteistic absorption configuration of oxygenated hemoglobin toward that indicative of the deoxygenated molecule.

Effect of Acclimation Time on Nitrite Movement Across the Gill Epithelia of Rainbow Trout: The Role of “Chloride Cells”

Abstract Plasma nitrite concentration and the number of lamellar chloride cells were directly correlated in rainbow trout (Salmo gairdneri) transferred from isotonic seawater to fresh water, during a 96-h acclimation period. After a 48-h acclimation, plasma nitrite levels offish exposed to 175 mg/ L of nitrite for 2.5 h were significantly higher than those offish acclimated for 24 h. There was a 9.5-fold increase in the number of lamellar chloride cells during this period. These results suggest that nitrite may be transported across gill epithelia by means of the branchial anion exchange mechanism attributed to lamellar chloride cells in fresh water.

Recent advances in the fish by‐products industry

In recent years the fish by‐products industry has grown more rapidly than any other segment of the worlds fisheries. Production of fish meal, the primary product of the industry and an important feed ingredient, rose from 1,525,000 metric tons in 1958 to 5,080,000 metric tons in 1968. This tremendous increase in production was the result of improved fishing methods, expansion of established fisheries, and the development of new fisheries, particularly the anchoveta fishery of Chile and Peru. Although markets for fish meal were severely disrupted during the early part of the expansion, they subsequently exhibited a high order inelasticity and provide the basis for profitable operations.

Changes in Keys-Willmer Cell Numbers in the Gills of Steelhead Trout during Smoltification

Abstract Steelhead trout (Salmo gairdneri) were monitored from February to November 1981 for Keys-Willmer cell (filament and lamellae) counts, plasma Na+ and K+, body coloring, and condition factor. The data indicated that the fish experienced a pre-smolt peak in filament cell count followed by changes in condition factor, body color, and Na+ level. This was followed by a more significant peak in filament cells with a corresponding decrease in lamellae cells. Because no increase in salinity was experienced, cell counts reflected a return to a freshwater physiology.

Use of Specific-ion Electrode for the Determination of Un-ionized Ammonia in Fish Blood

Abstract An accurate and simple direct-injection method for the determination of whole blood ammonia in fish uses an ammonia-specific electrode fitted with a flow-through cap (Orion Research, Inc.). Blood from the dorsal aorta of 2-year-old steelhead trout (Salmo gairdneri) and coho salmon (Oncorhynchus kisutch) was obtained without contact with air and injected directly into the micro-flow-through cap for ammonia determination without prior treatment. To determine whether the results obtained by the Conway diffusion and the direct-injection methods were significantly different, we measured whole blood samples from steelhead trout simultaneously; the Conway method gave values 42% higher than the direct-injection method and a Students t-test verified that ammonia levels were significantly higher (P<0.005) by the Conway diffusion method. The difference was believed to be due to the base hydrolysis of labile nitrogen-containing compounds in fish blood. Test comparison of the direct-injection method and a pl...

The exposure of ammonia to the photodissociated hemoglobin of the marine bloodworm, Glycera dibranchiata

Abstract 1. 1. Ammonia was injected into an anaerobic reaction chamber containing non-liganded hemoglobin (from the bloodworm, Glycera dibranchiata ) obtained by employing a photolytic technique to dissociate carbon monoxide from the hemoglobin molecule. 2. 2. No major alteration of the absorbance spectrum was effected after exposure to ammonia and only after subsequent contact with air did a spectral change become apparent. 3. 3. This lends support to the contention that ammonia does not substantially exert a competitive effect with oxygen for the 6th coordinate position of the hemoglobin molecule.