Application of artificial photoperiod in fish: a factor that increases susceptibility to infectious diseases?

This paper describes and evaluates the mortality associated with the potential stressor effect induced by application of artificial photoperiods in rainbow trout (Oncorhynchus mykiss). After application of artificial photoperiods, high mortalities of trout subjected to this management were recorded (36% in LD 14:10 and 25% in LD 24:0) as compared to controls (7%). The recorded signology related to diseased trout included darkening, lethargy and erratic swimming.

Effects of different artificial photoperiods and temperatures on haematological parameters of rainbow trout (Oncorhynchus mykiss).

This study assessed the effects of two artificial photoperiods (LD 24:0 and LD 12:12) and three temperature regimes (9, 11, and 18 degrees C) for 30 days on haematological parameters of trout (Oncorhynchus mykiss) kept in freshwater. Samples were taken at days 7, 14, and 30 during exposure to treatments. A higher mortality (22%) and lower oxygen concentration (<8.

Hibernation alters the frog's immune system.

The lymphomyeloid organs and blood leukocyte populations of the leopard frog, Rana pipiens, undergo conspicuous changes during hibernation at 4 degrees C. Within the blood, spleen, thymus, jugular bodies, and bone marrow there was a progressive loss of hemopoietic populations resulting in a marked lymphocyte depletion. Termination of the 135-day hibernation period resulted in the restoration of all hemopoietic elements in the blood and lymphomyeloid organs within 30 days.

T-lymphocyte and B-lymphocyte dichotomy in anuran amphibians: II. Further investigations on the E-rosetting lymphocyte by using monoclonal antibody azathioprine inhibition and mitogen-induced polyclonal expansion.

We have continued to search for characteristics of T-lymphocytes in anuran amphibians. Inhibition assays using the monoclonal antibodies OKT-11 and T-11, the T-cell immunosuppressive drug azathioprine, and mitogens confirmed the nature of E-rosetting peripheral blood lymphocytes (PBL) in Rana pipiens. Both monoclonal antibodies specifically inhibited E-rosetting in a dose-dependent fashion; absorption of the monoclonals by frog PBL specifically removed inhibition on human E-rosetting T-cells.

T-lymphocyte and B-lymphocyte dichotomy in anuran amphibians: III. Assessment and identification of inducible killer T-lymphocytes (IKTL) and spontaneous killer T-lymphocytes (SKTL).

We have established the existence of alloreactive inducible killer (IK) T-lymphocytes in Rana pipiens by injecting immunogenic concentrations of allogeneic frog erythrocytes (RBC). Assessment of specific IK activity was determined microscopically, observing effector-target conjugate formation, and spectrophotometrically as released hemoglobin (Hb) from lysed targets (RBC). The presence of spontaneous killer (SK) T-lymphocyte activity was also determined using unimmunized frogs and similar assay conditions.