ABSTRACT
Juvenile clearnose skates (Raja eglanteria) were injected intramuscularly with dexamethasone-21-phosphate at 50, 75, and 100mg/kg body weight. After 24h, skates were sacrificed and lymphomyeloid tissues (thymus, spleen, Leydig organ, and epigonal organ) were removed and whole blood was sampled. Tissues were used fresh for imprints or prepared for histology by solvent fixation or freezing in liquid nitrogen. Apoptosis in fixed tissues was assessed by transmission electron microscopy. Frozen sections and cytospin preparations of peripheral blood leukocytes (PBL) were evaluated by the TUNEL reaction to detect DNA strand breaks. Dexamethasone treatment increased apoptotic activity in all lymphomyeloid tissues as well as in PBL. These studies demonstrate that immune cells of elasmobranchs have the capacity for glucocorticoid-driven apoptosis, and that programmed cell death as a mechanism to regulate immune cell production appears to have been conserved during vertebrate evolution.
Subject(s)
Apoptosis , Dexamethasone/analogs & derivatives , Dexamethasone/pharmacology , Glucocorticoids/pharmacology , Leukocytes, Mononuclear/drug effects , Leydig Cells/drug effects , Spleen/drug effects , Thymus Gland/drug effects , Animals , Dexamethasone/administration & dosage , Glucocorticoids/administration & dosage , Gonads/cytology , Gonads/drug effects , Leukocytes, Mononuclear/cytology , Leydig Cells/cytology , Lymphoid Tissue/cytology , Lymphoid Tissue/drug effects , Male , Skates, Fish , Spleen/cytology , Thymus Gland/cytologyABSTRACT
Square (2.54 x 2.54 cm2) 304 stainless steel metal plates were cleaned, passivated, and soiled by autoclaving (121 degrees C at 15 psi for 15 min) with reconstituted nonfat dry milk (20% solids). Fifteen-minute treatments using either warm water (40 degrees C) or ozonated cold water (10 degrees C) were conducted to compare prerinse cleaning potential of soiled metal plates. The chemical oxygen demand determination was performed on extracted organic material from treated metal plates. Results indicated that the ozone treatment removed 84% of soil from metal plates versus 51% soil removal by the warm water treatment, but the effectiveness of the two treatments did not differ (P > 0.05). Cleaning effects were visualized using scanning electron microscopy at 200x and 2000x magnification. The amount of soil film present on stainless steel metal surfaces was visibly lower on ozonated treatments versus on warm water treatments.