Biomedical subjects
P R Waterstrat
Publications and source records attributed to P R Waterstrat.
In vitro responses of channel catfish, Ictalurus punctatus, neutrophils to Edwardsiella ictaluri.
The in vitro responses of channel catfish peripheral blood neutrophils to Edwardsiella ictaluri were examined through the use of phagocytic, bactericidal, and chemiluminescent assays. Evidence from both light and electron microscopy indicate that catfish neutrophils appeared to phagocytose E. ictaluri. Although extracellular killing of E. ictaluri was observed, bactericidal assays did not demonstrate intracellular killing of E. ictaluri by neutrophils. Catfish neutrophils mount a chemiluminescent response to E. ictaluri which is enhanced by the presence of specific antibody. Incubation of catfish neutrophils with LPS from E. ictaluri appeared to suppress the chemiluminescent response to opsonized zymosan.
Effect of temperature on the immune system of channel catfish (Ictalurus punctatus)--I. Leucocyte distribution and phagocyte function in the anterior kidney at 10 degrees C.
1. Temperatures of 18 degrees C for acclimation or assay had minimal or no effect on channel catfish phagocyte function. Significant suppression was observed at 10 degrees C acclimation and assay temperature. 2. According to the results of a multiple acclimation/assay temperature combination study, the primary impact of temperature on phagocyte function was due to the assay temperature. 3. The only functional change caused by acclimation temperature was the possible adaptation of the respiratory burst. However, 10 degrees C acclimation did cause a decline in the number of lymphocytes in the anterior kidney but not the number of neutrophils. In a temperature-kinetic study, the suppressive effect of 10 degrees C assay temperature was confirmed. 4. Results of our study indicated that phagocytosis in channel catfish is temperature-mediated. However, phagocytes appeared to be more resistant to low temperature than lymphocytes, which implies the importance of phagocytosis in the defense mechanisms of channel catfish at low temperatures.
Effect of water temperature on the clinical outcome of infection with Edwardsiella ictaluri in channel catfish.
Channel catfish fingerlings (mean body weight, 19 +/- 3 g each) were given intraperitoneal inoculations of Edwardsiella ictaluri suspensions of 10(4), 10(5), or 10(6) bacteria. Control fish were inoculated intraperitoneally with sterile 0.85% NaCl solution. Ten-day trials were conducted at water temperatures of 17, 21, 23, 25, 28, and 32 C. Differences in mortality between E ictaluri-infected fish and fish used as controls were observed at water temperatures of 23, 25, and 28 C, but not at temperatures of 17, 21, and 32 C. Clinical signs and lesions induced by intraperitoneal inoculation of E ictaluri were comparable with those found with the intestinal form of the natural disease. The characteristic erosion of skin and muscle overlying the skull, known as the "hole-in-the-head" lesion, was not observed. A given fish may be susceptible to infection at any water temperature, but a population is at risk when water temperatures are in the 22 to 28 C range.