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1. A single injection technique for GFR (14C-methoxyinulin clearance) was adapted for use in small mammals and applied to wild house mice (Mus musculus). 2. GFR in controls was 247 +/- 14(SE) microliter/min while that of mice acclimated to water shortage was reduced some 44%.
1. 32P-labelled inorganic phosphate incorporation into total and mitochondrial phospholipids was studied, in vitro, on brown adipose tissue (BAT) of control and cold-acclimated rats. 2. It was found that norepinephrine acts as in vivo, on BAT phospholipid metabolism via alpha 1 adrenergic receptors specifically increasing phosphatidic acid and phosphatidylinositol turnover with the same magnitude in both groups. 3. Cold-induced alpha 1 adrenergic desensitization is not as important as cold-induced beta adrenergic desensitization. 4. No specific effect of norepinephrine was seen in mitochondrial phospholipid turnover.
Total, as well as free, T4 and T3 levels were obtained over four seasons for young male infantry soldiers assigned to interior Alaska. Significant seasonal variations were found in both T3 and T4. Total T4 and T3 levels were highest in winter, while free T4 and T3 levels were highest in early spring. Correlations with melatonin levels from a concurrent study showed an association between late day (17.00) mean spot melatonin levels during the preceding summer and T3 levels in winter and spring. Differences in seasonal T4 and T3 levels between indigenous and newly arrived people in the sub-Arctic may be related not only to cold acclimation but also to light.
The effects of adenosine on synaptic transmission were studied with extracellular recordings of stimulus-induced population action potentials in area CA1 of hippocampal slices prepared from hibernating (HH) and warm-acclimated Turkish hamsters (WH) and rats. In HH as well as WH and rat slices, adenosine generally reduced the population spike amplitude and the slope of the field EPSP. The sensitivity for adenosine was significantly lower in HH slices than in WH and rat slices. The results are discussed with regard to the involvement of endogenous adenosine in the regulation of neuronal activity during entrance into and arousal from hibernation.
Tetanus-induced long-term potentiation (LTP) of population action potentials at 22 degrees C was investigated in area CA1 of hippocampal slices prepared from hibernating (HH) and warm-acclimated Turkish hamsters (WH) and rats. LTP elicited at this temperature was significantly stronger in HH slices compared to WH and rat slices. Hibernation-related improvement of the ability to develop long-lasting enhancement of synaptic transmission at low temperatures is interpreted as supporting hippocampal function during arousal from hibernation.
The effects of histamine on synaptic transmission were studied at 37 degrees C and 22 degrees C with extracellular recordings of stimulus-induced population action potentials in area CA1 of hippocampal slices prepared from hibernating (HTH) and warm-acclimated Turkish hamsters (WTH) and rats. In rat slices, application of 50 microM histamine had no effects on population spikes and field excitatory postsynaptic potentials (EPSPs). In HTH as well as WTH slices, 50 microM histamine generally increased the population spike amplitude. The slope of the field EPSP was unchanged. At 37 degrees C, the sensitivity for histamine was significantly higher in HTH slices than in WTH slices. At 22 degrees C, the effects of histamine were less pronounced in HTH as well as WTH slices. Hibernation-related improvement of sensitivity for histamine is interpreted as supporting hippocampal function during arousal from hibernation.
The protease activity, as assayed at pH 8.0 with azocasein as substrate, of a ciliate protozoan Tetrahymena pyriformis NT-1, was found to alter by growing the cells at various constant temperatures or at shifted temperatures. The intracellular protease activity, when cells were grown at either constant 39 degrees C or 15 degrees C, was decreased throughout the growth phase with significant secretion into the medium. On the other hand, when the culture temperature was transferred from 39 degrees C to 15 degrees C, the protease activity in cells was greatly increased up to about 28-fold at 8 h after the shift. There was, however, no secretion into the medium during the cold acclimation after the shift, where no cell division occurred. The elevated protease activity was quickly decreased to the control level when the culture was warmed to 39 degrees C after 8-h chilling, and recovery of normal cell division was seen. The marked increase in the protease activity caused by the shift to 15 degrees C was completely blocked by the addition of either cycloheximide or actinomycin D. The thermally induced enhancement of protease activity was found to occur with no different preference between three protease fractions.
Digitalis-like compounds (DLC) were shown to be a normal constituent of the skin and plasma of toads. In order to assess the possible physiological role of these compounds in the toad, their levels were determined in the brain, plasma and skin following acclimation in different NaCl solutions. We demonstrate that an increase in salt concentrations in the animal medium from 0 to 1.2% decreased the levels of DLC in the brain by 50% without altering significantly its levels in the plasma and skin. An increase in medium salt concentration to 1.5% resulted in a 50% increase of DLC levels in the skin without changing its levels in the plasma or brain. These results suggest that skin and brain DLC may participate in the long-term salt and water homeostasis in the toad, while the plasma compound either participates in the short-term regulations of salt and water homeostasis or have some other, unknown, function.
1. Some glycolytic metabolites were determined for red muscle (RM) and white muscle (WM) of goldfish acclimated to 10 and 25 degrees C. 2. Lactate/pyruvate (L/P) was higher in RM than in WM. 3. Lactate dehydrogenase (LDH) of RM was slightly more susceptible to inhibition by lactate than WM-LDH. At L/P found in vivo under resting conditions, RM-LDH was about three times as inhibited as WM-LDH. 4. When 25 degrees C-fish were forced to swim at 25 degrees C, the increase of L/P in WM was mainly due to increased lactate level and that in RM was ascribed to decreased pyruvate level. These changes were obscure in 10 degrees C-fish.
The mean Km and Vmax values for G3PDH isolated from the lateral muscle of cold-adapted (5 degrees C) rainbow trout, Salmo gairdneri, were twice those of enzyme from warm-adapted (15 degrees C) trout when assayed at 7 degrees C but not at any other temperature. The entropy of activation of warm enzyme was about 3 times that of cold enzyme. However, enthalpy or free energy of activation among acclimation groups differed less or not at all. Individual G3PDH isolates within either adaptation group differed in kinetic characteristics.
G3PDH was isolated from the lateral muscle of rainbow trout (Salmo gairdneri) acclimated at 5 degrees C (cold) and 15 degrees C (warm). No differences were found in muscle concentration, molecular weights, isoelectric focusing patterns, amino acid compositions or peptide maps between cold and warm isolates. Cold and warm G3PDH contained mannose in variable concentration but no other prosthetic groups.
Apparent Km value for GDP-mannose remained stable when trout were raised and when enzyme activity was assayed at temps corresponding to the natural biological temp (between 5 and 15 degrees C). The Km value increased when the temperature of the assay was higher than 21 degrees C. Marked increase of the Km value was observed when trout were acclimated at 21 degrees C, whatever the temperature of the assay between 5 and 30 degrees C.
Conjugative metabolism and biliary excretion of phenolphthalein (PP) were studied in steelhead trout (Salmo gairdneri) acclimated to 10, 14 or 18 degrees C. Significant seasonal effects were found on liver weight to body weight ratio and conjugative metabolism but not biliary excretion of free plus conjugate of PP. Temperature did not significantly interact with these relationships. PP was excreted in bile as parent compound and the glucuronide conjugate at all temperatures. Saturation of the excretory process was apparent at a dose of approximately 10 mumol/kg (i.p.) at 10 and 14, but not 18 degrees C.
The effects of temperature acclimation at 10, 20 and 30 degrees C on the concentration and activity of the mixed function oxidase system in bluegill are as follows. Liver weight/body weight varied inversely with temperature. Significant (P less than 0.05) differences in concentration of cytochrome P-450 of hepatic microsomes were seen and varied inversely with temperature. Benzo(a)pyrene hydroxylase activity tested in vitro at incubation temperatures of 10, 20 and 30 degrees C showed significant differences in Km, but no differences in Vmax. SDS polyacrylamide gel electrophoresis revealed some quantitative differences in cytochrome P-450 isozymes between groups.
Growth curves, cellular Zn contents and cellular protein expression were examined for the green alga, Chlorella kesslerii, as a function of different Zn growth regimes (growth in 16 pM, 1.7 nM or 1.6 microM calculated Zn2+). Zn homeostasis was responsible for observed differences in the capacity of the organism to accumulate Zn. The rapid acclimation that occurred in response to a Zn deficiency was likely due to the production of Zn transport sites. No differences were observed among cellular phytochelatin contents or efflux rate constants, although efflux did play an important role in regulating Zn cellular content. A long-term adaptation to Zn was not thought to occur since bioaccumulation and biological responses were similar for four successive cultures (30-40 days, 16-19 cell cycles) at different [Zn2+]. Among proteins that were influenced by the Zn growth regime, the Rubisco and histone H3 proteins were identified as being induced in the presence of 1.6 microM Zn2+ as compared with 1.7 nM Zn2+. The impact of the Zn preconditioning demonstrated that the concentrations of essential metals in the algal growth media would have an important, if not predominant effect on toxicity or bioaccumulation assessments. Furthermore, the high regulation of Zn transport and intracellular events by the microorganisms will likely preclude the use of simple metal uptake models including the free ion activity model and the biotic ligand model to predict either bioaccumulation or toxicological effects of Zn and perhaps other essential metals.
In this study, anaerobic treatability and biogas generation potential of broiler and cattle manure were investigated. For this purpose, seven sets of anaerobic batch reactor experiments were performed using broiler and cattle manure and their mixtures in five different ratios (100% broiler; 75% broiler, 25% cattle; 50% broiler, 50% cattle; 25% broiler, 75% cattle; 100% cattle). These manure mixtures had two different initial chemical oxygen demand (COD) (12,000 and 53,500 mg/l) concentrations. The effects of initial COD concentration, nutrient and trace metal supplementation, microbial acclimation and digestion temperature were investigated. Results revealed that the efficiency of total COD removal was 32.0-43.3% and 37.9-50% for initial COD concentrations of 12,000 and 53,500 mg/l, respectively. The biogas yields observed for initial COD concentrations of 12,000 and 53,500 mg/l were 180-270 and 223-368 ml gas/g COD added, respectively. A decrease in biogas yield was observed as the fraction of broiler manure increased in mixture of broiler and cattle manure at initial COD values of 53,500 mg/l.
Colonies of Pocillopora damicornis from Kaneohe Bay and colonies of Pocillopora meandrina from a thermal outfall site and a control site at Kahe were exposed to three different temperatures (29, 32 and 33 degrees C) in outdoor aquaria on running water tables for five days. Samples (n=3) were taken from each treatment at 0800, 1200 and 1600 h. ELISAs using catalase antibodies and ferric reducing/antioxidant potential (FRAP) assays were run on the samples to determine how antioxidant levels changed throughout the experiment. Light levels during the experiment were highest in the morning ( approximately 1000-1500 micromol quanta m(-2) s(-1)) and decreased to 25-60 micromol quanta m(-2) s(-1) by 1100 h and remained low until sunset. Antioxidant concentrations were highest in the morning for P. damicornis from Kaneohe and P. meandrina outfall samples. There was no significant change through the day for P. meandrina samples from the control site. The difference in response between the outfall samples and the control samples suggests that P. meandrina has acclimated to elevated temperatures found at the outfall site.
Seasonal hematological adjustments in small mammals may include changes in the number and size of the red cells or changes in other linked blood parameters. The direction and magnitude of these changes vary in different species. We hypothesized that the observed variations of the red cell adjustments could be directly related to the magnitude of the seasonal temperature differential, and predicted that the annual red cell size variation in rodents from environments with marked seasonal changes would tend to disappear, if the animals were raised under milder and constant environments. To test this idea, we got field blood samples from the Andean species Phyllotis xanthopygus rupestris enduring a winter-summer thermal differential of at least 20 degrees C. These animals had significantly smaller erythrocytes during the winter. Contrary to our prediction, their offspring born and raised under constant temperature conditions showed a similar trend. Unless the effective environmental cue differed from the one we used, these results favor the idea of a genetically determined annual red cell size variation that occurs independent of thermal acclimation and acclimatization.