Social facilitation of reduced oxygen consumption in Mus musculus and Meriones unguiculatus

• 1.1. The short-term resting rates of oxygen consumption of laboratory white mice (Mus musculus) and Mongolian gerbils (Meriones unguiculatus) were measured by closed system manometry.
• 2.2. Metabolic rates of animals tested individually were compared to those of huddled trios and trios in which the animals were tested simultaneously but prevented from physical contact (separated trios) at temperatures ranging from 9–25° C.
• 3.3. Rates of increase of weight-specific resting metabolism were greatest for animals tested individually.
• 4.4. There was no significant difference in the rates of increase of oxygen consumption between huddled and separated trios in cither species.

     

The effect of myo-inositol on the ability of Ditylenchus dipsaci,D. myceliophagus and Anguina tritici to survive desiccation

• 1.1. The effect of myo-inositol on the ability of three species of nematodes to survive desiccation has been studied.
• 2.2. Survival rates obtained from worms treated with an inositol bathing medium were compared with survival rates of worms treated with distilled or tapwater media.
• 3.3. Highest survival rates were found in those nematodes that were placed in an inositol solution prior to desiccation.
• 4.4. Tapwater facilitated higher revival rates than did distilled water in both D. dipsaci and D. myceliophagous.
• 5.5. No such differences were found for A. tritici.
• 6.6. The results are discussed in relation to the possible mechanisms of protection afforded by the different bathing media.

     

Individual and sibling-group variation in metabolism of lizards: The aerobic capacity model for the origin of endothermy

• 1.1. We measured standard, resting and exercise metabolism of 28 Chaicides ocellatus (Scincidae). Individual lizards consistently showed statistically significant differences in mass-independent rates of standard and exercise metabolism during three replicates of the experiments at weekly intervals.
• 2.2. Metabolic differences were also detected among groups of siblings.
• 3.3. Mass-independent resting metabolic rates were closely correlated with standard rates, but there was no correlation of metabolic rates during forced activity with either standard or resting rates.
• 4.4. These data suggest a heritable component of metabolism for lizards, but they do not support the “aerobic capacity model” of the origin of endothermy, which proposes that initial selection for high resting metabolic rates operated via selection for high rates of aerobic metabolism during exercise.

     

The effects of artificial solar radiation on wind-stressed tufted titmice (Parus bicolor) and Carolina chickadees (Parus carolinensis) at low temperatures

• 1.1. Changes in metabolic rates and behavior were observed in tufted titmice (Parus bicolor) and Carolina chickadees (Parus carolinensis) exposed to varying conditions of artificial solar radiation, wind, and temperature in a wind tunnel experiment.
• 2.2. During the wind-on condition, both species showed a significant decrease in mean metabolic rates in the high radiation treatments when compared to the low radiation treatments (P < 0.05).
• 3.3. Titmouse orientation, posture and level of activity were significantly affected by radiation and wind conditions.
• 4.4. Metabolic rates observed in the wind tunnel treatments without wind and at low radiation did not significantly differ from similar standard metabolic (black box) treatments (P > 0.05).
• 5.5. Activity levels did not appear to directly affect metabolic rates observed in the wind tunnel treatments.

     

Rates of heat exchange in the ornate box turtle,Terrapene ornata

• 1.1. Eight ornate box turtles, Terrapene ornata, were heated and cooled in water at 35 and 15°C respectively.
• 2.2. Thermal time constants were calculated and no significant differences were found (t-test; 0.05 level) between warming and cooling rates.
• 3.3. Heart-rate data indicated slightly higher, but non-significant, mean values during warming.
• 4.4. It was concluded that T. ornata is not able to physiologically alter rates of heat exchange in water significantly and must rely on behavioral mechanisms to maintain body temperature.

     

The relationship between osmoregulation and nitrogen metabolism in the intertidal prawn,Palaemon elegans (Rathke)

• 1.1. The relationship between nitrogen metabolism and osmoregulation has been studied in the prawn Palaemon elegans (Rathke) following sudden exposure to hyper- and hyposaline conditions.
• 2.2. Animals acclimated to a salinity of 30‰ showed a pronounced increase in the rates of ammonia excretion during the first 2 hr after transfer to lower salinities. These gradually declined during the next 6 hr to rates that were significantly higher than that of control animals (30‰) and were maintained throughout the rest of the experiment.
• 3.3. Rates of ammonia excretion in animals transferred to hypersaline conditions (40‰) fluctuated considerably during the experiment. It was consistently observed, however, that there were two periods during the experiments when ammonia excretion rates had negative values indicating that NH⁺₄ ions were being taken up by the prawns.
• 4.4. Experiments in which small quantities of (NH₄)₂SO₄ containing the stable isotope ¹⁵N were added to the sea-water confirmed that P. elegans was able to take NH⁺₄ ions from the sea-water.
• 5.5. Changes in the Na⁺ ion concentration in the blood and the changes in free amino acid concentration in the blood and in the muscle after exposure to differing salinities were also determined. Their significance and relationship to the observed changes in the rates of ammonia excretion are discussed.

     

Oxygen consumption and production by tropical ascidians symbiotic with Prochloron

• 1.1. Oxygen consumption and production rates were measured in two species of colonial ascidians that contained the algal symbiont, Prochloron.
• 2.2. Despite differences in size and habitats, the colonies showed similar rates of oxygen consumption and production.
• 3.3. Oxygen production by the colonies was light dependent.
• 4.4. Based on the data presented, the symbiosis is similar to other algal-invertebrate symbioses in producing more oxygen than is consumed when illuminated.

     

Heart rates of sea snakes diving in the sea

• 1.1. Classical diving bradycardia was not evident in sea snakes diving in the sea.
• 2.2. Activity increases heart rate both in apneic and in breathing snakes; there is a breathing tachycardia in the laboratory and in the sea.
• 3.3. Heart rates obtained from animals diving in the sea (26 m depth) were similar to those obtained under laboratory conditions if allowances are made for activity differences.
• 4.4. Handling and stress increases heart rates of sea snakes.

     

Human-induced tachycardia in wild and tame mallard (Anas platyrhynchos)

• 1.1. The effect of regular handling on fear reactions was investigated in mallard (Anas platyrhynchos) by exposing six hand-reared and four wild ducks to an approaching human being and recording heart rates with an external ECG device.
• 2.2. All ducks reacted to the approach with tachycardia, but the response was significantly less in tame birds.
• 3.3. Hand-reared females showed less response than males. No sex-linked differences were apparent in the wild ducks.
• 4.4. Decreasing responses throughout the experiments were only found in tame birds.
• 5.5. Fear or stress reactions can apparently be diminished through habituation induced by regular handling.

     

Geographical variation of heat sensitivity and water loss rates in the tropical lizard,Anolis gundlachi

• 1.1. Sensitivity to high temperatures and desiccating conditions were separately measured in four samples of Anolis gundlachi collected over an altitudinal transect and one sample of lowland A. cristatellus.
• 2.2. Critical thermal maxima (CTM) of gundlachi samples varied inversely in perfect rank order with elevation from a low of 33°C at 850m to a high of 36°C at 270m. The data suggest a possible genetic basis of the variation. No other measures of heat sensitivity exhibited significant altitudinal variation in gundlachi.
• 3.3. Rates of evaporative water loss among gundlachi samples exhibited the same pattern of population differentiation as did the CTMs. Survival times also varied among samples, but vital limits of desiccation did not.
• 4.4. A. cristatellus was invariably more heat and desiccation resistant than its montane counterpart, A. gundlachi.

     

Respiration in the eastern water dragon,Physignathus lesueurii (agamidae)

• 1.1. Some aspects of the gas exchange system of a diving lizard, Physignathus lesuewii were studied.
• 2.2. Breathing patterns were analysed.
• 3.3. Breathing rate increases logarithmically with temperature and Q₁₀ = 1.8. LogBR = −0.237 + 0.0256 T.
• 4.4. Gas tensions in lung air and arterial and venous blood were measured. Arterial pH declines with increasing temperature.
• 5.5. Temperature has a marked effect on oxygen affinity of the blood (ΔH = −10.1 kcal mol⁻). A Bohr effect was also noted.
• 6.6. CO₂ equilibrium curves were drawn.
• 7.7. The results are considered with a view to anticipating the efficiency of the gas exchange system of this species under conditions of variable temperature and during diving.

     

Bioelectric activity from isolated brain of Lacerta atlantica

• 1.1. A method of maintaining the isolated lizard brain in a Ringer solution is described.
• 2.2. Microelectrodes and EEG recordings from different areas of telecenphalon and optical tectum were made.
• 3.3. The prolonged cells survival under the experimental conditions described has been demonstrated for several hours.
• 4.4. The isolated brain of Lacerta makes it easy to reach anatomical pathways which otherwise, in the whole animal, would be more difficult to reach.

     

Reduction of ferrihemoglobin in erythrocytes of birds and mammals

• 1.1. Species differences exist in ferrihemoglobin reduction rates in bird and mammalian red cells, bird erythrocytes being very active reducers.
• 2.2. Glucose and lactate enhance ferrihemoglobin reduction. In horse and quail red cells β-hydroxybutyrate has this effect as well.
• 3.3. Malate and pyruvate do not enhance ferrihemoglobin reduction.
• 4.4. Plasma addition to red cell suspensions enhances ferrihemoglobin reduction; addition of lactate mimics this effect in all species except the dog.
• 5.5. Incubation conditions are very important for measuring ferrihemoglobin reduction. Especially the presence of bicarbonate ions is essential. In our experiments no inhibition of reduction rates by chloride ions is found.
• 6.6. Mitochondrial NADH production does not play a role in ferrihemoglobin reduction in bird red cells.

     

Effects of water stress on hemolymph volume,osmotic potential and chemical composition in Megetra cancellata

• 1.1. Rates of water loss in Megetra cancellata were very high compared to those reported for other xeric arthropods.
• 2.2. Hemolymph weight in hydrated animals was 43.0% of the total body weight while it was 24.7% in desiccated animals that had lost 16.1% of their body weight as water.
• 3.3. Hemolymph osmotic potential increased from 417 to 447 mOsm/kg in desiccated beetles, but osmotic regulation was evident.
• 4.4. Total hemolymph protein mass and concentration decreased in desiccated beetles while amino acid concentrations remained constant (at about 70 mM).
• 5.5. Na⁺ and −PO₄ concentrations increased in desiccated beetles.
• 6.6. Cl⁻ and K⁺ concentrations in desiccated beetles were equal to those in undesiccated beetles.

     

Monoclonal antibodies neutralizing the haemolytic activity of box jellyfish (Chironex fleckeri) tentacle extracts

• 1.1. Three monoclonal antibodies have been produced which neutralize in vitro the haemolytic activity present in tentacle extracts of the box jellyfish (Chironex fleckeri).
• 2.2. Two of these monoclonal antibodies bound specifically to a component of relative molecular mass 50,000 in tentacle extract on Western blots.
• 3.3. This binding only occurred when the extracts were electrophoresed under non-reducing conditions.
• 4.4. The third monoclonal antibody did not display binding to Western blots of tentacle extract under any of our experimental conditions.

     

Purification and some properties of an atypical alkaline p-nitrophenylphosphate phosphatase activity from Halobacterium halobium

• 1.1. An alkaline p-nitrophenylphosphate phosphatase has been purified 440-fold from extracts of Hatobacterium halobium.
• 2.2. The enzyme has an apparent molecular weight of 24,000.
• 3.3. A K_m value for p-nitrophenylphosphate of 1.12mM has been found under optimal conditions.
• 4.4. The enzyme is selectively activated and stabilized by Mn²⁺.
• 5.5. It requires high salt concentrations for stability and maximum activity.
• 6.6. It displays an unusual restricted substrate specificity of 25 phosphate esters tested, only phosphotyrosine and casein were hydrolysed besides p-nitrophenylphosphate.

     

Mitochondria from the ventricle of the marine clam,Mercenaria mercenaria: Substrate preferences and effects of pH and salt concentration on proline oxidation

• 1.1. Mitochondria with high respiratory control ratios (RCR) have been isolated from the ventricle of the marine clam Mercenaria mercenaria.
• 2.2. Proline is the preferred substrate of the mitochondria of the ventricle based on state 3 rates.
• 3.3. Pyruvate, ornithine and succinate are oxidized at rates 3/4 that of proline.
• 4.4. α-Glycerophosphate was oxidized at rates 1/2 that of proline.
• 5.5. The pH optimum for proline oxidation lies between 6.5 and 7.5 based on RCR and ADP/O and between 7.0 and 7.4 based on state 3 rates.
• 6.6. KCl concentrations between 250 and 450 mM gave optimal values for the oxidation of proline based on RCR and state 3 rates.
• 7.7. KCl concentration had little effect on ADP/O between 100 and 850 mM.

     

Temperature acclimatization in the filtering rates and oxygen consumption of Daphnia ambigua scourfield

• 1.1. Filtering rates and oxygen consumption were measured in the field on a wild population of the fresh-water limnetic cladoceran Daphnia ambigua.
• 2.2. Filtering rates increased with increasing body size and were significantly affected by environmental temperature.
• 3.3. Oxygen consumption increased with increasing body size; there was no significant difference among b values determined at different environmental temperatures but bs were highest at low temperatures. decreased progressively at higher temperatures and increased at the highest temperatures.
• 4.4. Temperature significantly affected the rate of oxygen consumption.
• 5.5. Both filtering rates and oxygen consumption evidenced classical translation to the left in cold-acclimatized animals. An environmental temperature near 12°C apparently separates warm- and cold-acclimatization processes.

     

Adaptative features of amazon fishes: Hemoglobins,hematology, intraerythrocytic phosphates and whole blood Bohr effect of Pterygoplichthys multiradiatus (Siluriformes)

• 1.1. Hemoglobin, hematological parameters, intraerythrocytic phosphates and whole blood Bohr effect of Pterygoplichthys multiradiatus, from the Amazon river, were studied in three different conditions: in their natural environment, acclimated to normoxia and acclimated hypoxia conditions.
• 2.2. Nine anodal hemoglobin fractions were detected on starch gel electrophoresis. No qualitative differences in the Hb electrophoretic patterns were detected in the three studied groups.
• 3.3. Hematocrit, hemoglobin concentration, MCV, MCHC and MCH were different among studied conditions.
• 4.4. GTP was almost absent in the blood of animals in natural conditions and acclimated to hypoxia, but was present at a concentration similar to ATP in normoxic acclimated animals.
• 5.5. There is a tendency for higher Hb-O₂ affinity for hypoxic acclimated/acclimatized animals.

     

Environmental and genetic influences on the thermal physiology of Rana sylvatica

• 1.1.|Intraspecific variation in the thermal physiology of Rana sylvatica was examined.
• 2.2.|Heat and cold tolerances of both adult and larval representatives were determined for animals representing populations from New York, Maryland, Kentucky, Ohio, Michigan and Canada.
• 3.3.|In general, frogs from more northern localities exhibited lower heat tolerances.
• 4.4.|There was no evidence of interpopulational differences in cold tolerance. Similar trends were revealed by larval testing.
• 5.5.|Interpopulational differences among laboratory-reared tadpoles suggests a strong genetic component to Rana sylvatica thermal physiology.