Synthesis of rat hepatic zinc thionein in response to the stress of sham operation

Following sham operation for adrenalectomy, a dramatic 30-fold increase in rat hepatic zinc thionein occurs, peaking at 18 hours after surgery. Hepatic cytosolic and serum zinc levels rise concomitantly with zinc thionein. Copper in hepatic thionein and cytosol rises only slightly and serum copper not at all during the period of observation. In the period 18 to 48 hours after surgery the content of hepatic zinc thionein decreases with a $\text{t}\text{1}\text{2}$ of 16.4 hours.Pretreatment with cycloheximide (1 mg/kg b.w.) two hours before surgery inhibits the rise in zinc thionein by 52%, the rise in cytosolic zinc by 56%, and actually causes a decrease in serum zinc by 33%. Pretreatment with the α-adrenergic receptor blocker, phetolamine (10 mg/kg b.w.), or the β-adrenergic receptor blocker, propranolol (10 mg/kg b.w.), 30 minutes before surgery also inhibited the rise in zinc thionein (82% and 60%, respectively) and cytosolic zinc (75% and 47%, respectively), and decreased serum zinc (38% and 44%, respectively) 19 hours after surgery.Treatment with corticosterone (40 mg/kg b.w.) alone or epinephrine (1–20 μg/kg b.w.) alone did not alter hepatic zinc thionein levels 18 hours late, although they each caused hypozincemia and epinephrine raised cytosolic zinc levels. Treatment with corticosterone and epinephrine together did, however, raise zinc thionein levels 3.2-fold (P<0.02).These experiments are consistent with the hypothesis that adrenal hormones are involved in the regulation of zinc metabolism, and, hence, zinc thionein in levels in rat liver following the stress of sham operation.     

Phycomyces: electrical response to light stimuli

Electrical signals have been detected in response to light excitation of the fungus Phycomyces blakesleeanus. These signals are related to the wavelength and intensity of the stimulus and the growth stage of the fungus. A relationship between the signals and the possible photoreceptor-pigment system is explored.     

Immune response of mallard ducks treated with immunosuppressive agents: antibody response to erythrocytes and in vivo response to phytohemagglutinin-P

The ability of two in vivo tests to assay immune competence of mallard ducks (Anas platyrhynchos) treated with various immunomodulatory agents was examined. Skin responses to phytohemagglutinin-P (PHA-P) injected intradermally and serum antibody levels produced in response to sheep red blood cells (SRBC) were measured. As measured by the skin response to PHA-P, ducks injected intramuscularly with cyclophosphamide or cyclosporine did not respond differently from control-injected ducks. Dexamethasone injected intramuscularly significantly suppressed the skin response to PHA-P. As measured by antibody levels in response to SRBC, ducks injected intramuscularly with cyclophosphamide responded with antibody titers similar to controls. Cyclosporine injected intramuscularly reduced the level of immunoglobulin (Ig) G significantly in one of two experiments. Dexamethasone injected intramuscularly reduced peak total and IgG titers. These experiments provide information on the viability of these two in vivo tests to reflect immune competence of mallard ducks.     

A new approach to immunoFET operation

A new method is presented for the detection of an immunological reaction taking place in a membrane, which covers the gate area of an ISFET. By stepwise changing the electrolyte concentration of the sample solution, a transient diffusion of ions through the membrane-protein layer occurs, resulting in a transient membrane potential, which is measured by the ISFET. The diffusion rate is determined by the immobile charge density in the amphoteric protein layer, which changes upon formation of antibody-antigen complexes. No membrane potential is induced at zero fixed charge density as occurs at a protein characteristic pH. Isoelectric points of embedded proteins can be determined by detecting the zero potential response. Up to now, the authors have studied the membrane adsorption of lysozyme, human serum albumin (HSA) and the immune reaction of HSA with the antibody anti-human serum albumin (alpha HSA). The influence of protein parameters on the amplitude of the transient can be described with an empirical equation. Assuming Langmuir behaviour, the protein concentration in the solution can well be correlated with the concentration in the membrane. This new detection method is unique concerning direct measurements of charge densities and isoelectric points of amphoteric macromolecules adsorbed in the membrane. The simple procedure of one incubation stage followed by one detection stage, without separate washing and labelling techniques, gives direct information about specific charge properties of the macromolecules to be studied.     

Wolverines and declining snowpack: response to comments

The critiques by DeVink et al. (2010) and McKelvey et al. (2010) are flawed for several reasons. We show here that, contrary to what DeVink et al. claim, the influence of annual pelt price on wolverine harvest returns is essentially negligible. DeVink et al. also suggest that our results show the influence of snowpack on trapper success, rather than on actual wolverine population dynamics. This is unlikely, since most of the snowpack terms in our models are at 1- or 2-year time lags, whereas the impact of snow conditions on trapper success can only manifest in the current year. Both DeVink et al. and McKelvey et al. claim that wolverine populations across Canada are actually increasing, but provide no quantitative data to support this claim. Both sets of authors present alternative explanations for the declines in harvest returns, but none of those explanations are mutually exclusive with our own, and none can explain the significance of time-lagged snowpack on annual harvest returns. McKelvey et al.’s claim that our results represent a spurious correlation, as well as other points that they raise, suggests either a superficial understanding or deliberate misrepresentation of our methods and can simply reflect their underlying philosophical biases.     

Chlorophyll budgets: response to food web manipulation

Budgets for chlorophyll a and selected degradation products were constructed during summer stratification in 1984 and 1985 in two lakes. In Paul Lake, the reference ecosystem, pigment sedimentation showed no significant interannual differences. In Tuesday Lake, fish manipulations in May 1985 changed the zooplankton from an assemblage of Bosmina and small cyclopoids to one of large cladoceran grazers. Sedimentation of pigments, especially the grazing indicator pheophorbide a, increased significantly as the grazer assemblage changed. Mean grazer size was positively related to pheophorbide deposition rate in both lakes. Results of this whole-lake experiment indicate that major changes in lake food webs alter pigment deposition rates.