Energy metabolism and body temperature in 13 sunbird species (Nectariniidae)

• 1.1. Diurnal cycles of body temperature, T_b, and energy metabolism, M, at different ambient temperatures (T_a: +5 −+ 32°C) were tested in 13 sunbird species from various habitats and of different body masses (5.2–14.2 g) including one of the smallest passerines, Aethopyga christinae.
• 2.2. Resting M-level (night) reaches T_a-dependent mean values of 54% (+5°C) and 49% (+25°C) of activity M-levels (day). Expected level is ca 75%.
• 3.3. Resting metabolic rate of sunbirds lies within the range of theoretically expected values for birds.
• 4.4. Mean linear metabolism-weight regression of the night values follows: M = 0.102 × W^0.712 (M = energy metabolism in kJ/hr and W = body mass in g).
• 5.5. Thermal conductances, T_c, are lower (−24%) than the predicted values. This is caused by a decrease of T_b at low T_a. Mean nocturnal T_c is 3.2 J/g × hr × °C, mean day-time value is 4.3 J/g × hr × °C.
• 6.6. The zone of thermoneutrality is, in most species, within a T_a-range of 24–28°C.
• 7.7. Normal day and night levels of T_b are in the same range as reported for other birds of the same weight class. T_b decreases slightly with falling T_a (partial heterothermia). Lowest recorded T_b was 34.2°C.
• 8.8. No species tested showed any sign of torpor at night, independent of T_a, body mass or habitat origin.

     

Thermoregulation in the cicada Platypedia putnami variety lutea (Homoptera: Tibicinidae) with a test of a crepitation hypothesis

• 1.Measurements of body temperature (T_b) in the field demonstrate that Platypedia putnami var. lutea Davis regulates T_b through behavioral mechanisms.
• 2.Thermal responses (minimum flight temperature 17.3°C, maximum voluntary tolerance-temperature 32.5°C, and heat torpor temperature 44.4°C) of P. putnami var. lutea are related to the altitude of their habitat.
• 3.Water loss rates increase with ambient temperature (T_a). Water loss rates are not significantly different at the extremes of the active T_b range but increase significantly when exposed to elevated T_a.
• 4.Acoustic activity was restricted at 6.7°C T_b range. This is similar to the lower end of the T_b range for singing measured in cicada species that produce sound with a timbal mechanism.
• 5.The use of the wing musculature to produce acoustic signals in P. putnami var. lutea does not increase the T_b range over which the species can call compared to timbal calls produced by other cicada species.

     

Metabolic rate and body temperature of adult and juvenile hyrax (Procavia capensis)

• 1.1. Resting metabolic rates (RMR) below thermoneutrality in adult hyrax acclimated to 26, 15 and 10°C remained unchanged, i.e. thermal conductance (K) remained constant.
• 2.2. Conductance in juveniles decreased with acclimation to lower ambient temperatures (T_a).
• 3.3. Body temperature (T_b) dropped by 3.8°C in adults exposed to T_a of 30 – 5°C. The decrease was constant.
• 4.4. Body temperature fell by 1.5°C in juveniles exposed to T_a of 30 – 20°C but stabilized between 20 and 5°C.
• 5.5. The labile T_b, associated with behavioural strategies and lower than predicted RMR, can be seen as an energy-conserving mechanism of particular importance during winter conditions.

     

Determination of temperature preference and the role of the enlarged cheliped in thermoregulation in male sand fiddler crabs,Uca pugilator

• 1.Male Uca pugilator whose major cheliped was immersed in 3 °C water bath experienced a significant drop in T_b. Thus, the enlarged claw of male Uca pugilator may have an unexplored function: thermoregulation.
• 2.Crabs prefer warmer substrates (19–24 and 28–30 °C) over cooler (15–17 °C).
• 3.Mean selected temperature (MST) may not be an accurate reflection of T_b. Crabs in a thermal chamber preferred temperatures between 25 and 30 °C but their average T_b was 23.2 °C.

     

Brain temperature regulation of panting and non-panting pigeons exposed to extreme thermal conditions

• 1.1. Brain (hypothalamic), skin and body temperatures were measured in hand-reared acclimated (Acc, n = 5) and non-acclimated (NAcc, n =7) rock pigeons (Columba livia, mean body mass 237 g) exposed to increasing ambient temperatures (T_a) (30–60°C) and low humidities.
• 2.2. In non-panting Acc birds, brain temperature gradually increased from 40.1 ± 0.4°C at 30°C to 41.2 ± 0.4°C at 60°C T_a. A mean body temperature (T_b) of 41.2 ± 0.2°C was measured at T_a up to 50°C; an increase of 1.1°C was observed at 60°C (T_b 42.2 ±0.6°C).
• 3.3. In Acc panting birds exposed for 2 hr to 60°C, T_hy was 41.9 ± 0.8°C and T_s was somewhat (but insignificantly) higher, i.e., 42.2 ± 0.7°C. It looks as if both values were increased as a result of a slight hyperthermia that developed (T_b = 43.5 ± 0.9°C).
• 4.4. The significance of the present results for evaluating neuronal thermoresponsiveness of birds' hypothalamus is discussed.

     

Three digestive tract endocrine peptides and the circannual cycle of body weight in Spermophilus lateralis

• 1.1. Thirty-one male golden-mantled ground squirrels were divided into four physiological groups: low wt summer, medium wt summer, high wt summer and hibernation period. A second group of 10 females was divided into two groups: hibernation period at low T_b and hibernation period during a periodic arousal.
• 2.2. Blood serum, pancreas and antral stomach region were collected from each animal.
• 3.3. The serum was analysed by radioimmunoassay for pancreatic polypeptide immunoreactivity, the pancreas for pancreatic polypeptide and somatostatin immunoreactivity and the antral region of the stomach for gastrin immunoreactivity.
• 4.4. Significant between-stage differences (P < 0.05) were found in serum pancreatic polypeptide concentration and in pancreatic somatostatin content.

     

Some properties of ATPase activity in the intact cells of yeast Saccharomycopsis fibuligera

• 1.1. The properties of ATPase activity were studied with the cells at the early stationary phase of Saccharomycopsis fibuligera.
• 2.2. Optimal pH for the activity was approximately 7.
• 3.3. The activity was stimulated by Mg²⁺.
• 4.4. The activity was inhibited by NaF, DCCD, oligomycin, NaN₃, NaVO₃, or PCMB but not inhibited by ouabain.

     

Oxygen consumption in the tortoise,Testudo hermanni G., subjected to sudden temperature changes in summer and autumn

• 1.1. A respirometer for long-term measurements of oxygen consumption in terrestrial vertebrates is described.
• 2.2. The tortoise, Testudo hermanni Gmelin, investigated in summer and autumn, presents a day-night rhythm of oxygen consumption at 28 and 18°C but not at 8°C.
• 3.3. The standard metabolic rate presents an important and constant thermal dependence in the range 8-18-28°C.

     

Thermal properties for digestive enzymes of a sub-antarctic beetle,hydromedion sparsutum (coleoptera,perimylopidae) compared to those in two thermophilic insects

• 1.1. Proteolytic, lipolytic, amylolytic and cellulolytic activities were studied in adults of the phytophagous beetle, Hydromedion sparsutum, indigenous to the sub-Antarctic island of South Georgia.
• 2.2. Gastric enzyme activities were measured at experimental temperatures of 5–40°C and results were compared with those obtained from two thermophilic insects, Gryllus bimaculatus and Tenebrio molitor.
• 3.3. Protease and lipase activities in Hydromedion were 10–15 times lower than in Gryllus and Tenebrio.
• 4.4. In the temperature range of 5–15°C, α-amylase activity from Hydromedion was only slightly lower than that from Gryllus.
• 5.5. Hydromedion gut homogenates exhibited a distinct cellulolytic activity, even at a low temperature of 5°C.
• 6.6. Cellulolytic activity in the digestive tract of Hydromedion was confirmed by the evolution of ¹⁴CO₂ after consumption of labelled cellulose.
• 7.7. The thermal properties of digestive enzymes agree well with the role of Hydromedion as primary decomposer in its ecosystem.

     

IDentification of a microsomal retinoic acid synthase as a microsomal cytochrome P-450-linked monooxygenase system

• 1.1. To characterize an enzyme which metabolizes retinal in liver microsomes, several properties of the enzymatic reaction from retinal to retinoic acid were investigated using rabbit liver microsomes.
• 2.2. The maximum pH of the reaction in the liver microsomes was 7.6.
• 3.3. The K_m and V_max values for all-trans, 9-cis and 13-cis-retinals were determined.
• 4.4. The reaction proceeded in the presence of NADPH and molecular oxygen.
• 5.5. The incorporation of one atom of molecular oxygen into retinal was confirmed by using oxygen-18, showing that the reaction comprised monooxygenation, not dehydrogenation.
• 6.6. The monooxygenase activity was inhibited by carbon monoxide, phenylisocyanide and antiNADPH-cytochrome P-450 reductase IgG, but not by anti-cytochrome b₅ IgG.
• 7.7. The enzymatic activity inhibited by carbon monoxide was photoreversibly restored by light of a wavelength of around 450 nm.
• 8.8. The retinal-induced spectra of liver microsomes with three isomeric retinals were type I spectra.
• 9.9. The microsomal monooxygenase activity induced by phenobarbital or ethanol were more effective than that by 3-methylcholanthrene, clotrimazole or β-naphthoflavone.
• 10.10. These results showed that the monooxygenase reaction from retinal to retinoic acid in liver microsomes is catalyzed by a cytochrome P-450-linked monooxygenase system.

     

In vitro substrate utilization for lipid synthesis in liver explants from hyperthyroid chickens

• 1.1. Indian River male broiler chickens growing from 7 to 28 days of age were fed diets containing 12, 18, 24 and 30% protein + 0 or 1 mg triiodothyronine (T₃)/kg of diet to study energetic costs of lipogenesis and the use of various substrates for in vitro lipogenesis.
• 2.2. De novo lipid and CO₂ production were determined in the presence of [1-¹⁴C]pyruvate, [2-¹⁴q]pyruvate, [3-¹⁴C]pyruvate, [2-¹⁴C]acetate and [U-¹⁴C]alanine.
• 3.3. Oxygen consumption was determined in mitochondrial preparations to estimate the energetic costs in expiants synthesizing lipid.
• 4.4. Radiolabeled CO₂ derived from [1-¹⁴C]pyruvate was used as an estimate of coenzyme A availability in liver expiants. Lipids derived from [2-¹⁴C]pyruvate, [2-¹⁴C]acetate and [U-¹⁴C]alanine estimate relative substrate efficiency.
• 5.5. Labeled CO₂ production from [1-¹⁴C]pyruvate was greatest in that group fed a 12% protein diet and least in the group fed a 30% protein diet.
• 6.6. In addition, T₃ increased CO₂ production from [1-¹⁴C]pyruvate.
• 7.7. The production of ¹⁴CO₂ from the second carbon of pyruvate or acetate was increased by T₃.
• 8.8. The low-protein diet (12% protein) increased (P <0.05) lipogenesis.
• 9.9. Adding T₃ to the diets decreased carbon flux into lipid from all substrates, but increased CO₂ production from all substrates without changing stage 3 and 4 respiration rates in mitochondrial preparations.
• 10.10. These observations imply that coenzyme A availability may have regulated de novo lipogenesis in the present study.
• 11.11. It was also concluded that previously noted effects of T₃ on intermediary metabolism may involve metabolic pathways that do not involve changes in mitochondrial function.

     

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.

     

Comparative study of the oxyhaemoglobin dissociation curve of four mammals: Man,dog, horse and cattle

• 1.1. The entire oxygen dissociation curve (ODC) and the effects of temperature, pH and 2,3-diphosphoglycerate (DPG) on this curve, have been compared in four mammalians: man, dog, horse and cattle.
• 2.2. If the oxyphoric capacities are similar between these species (around 1.39ml O₂/gHb), their P50, measured in standard conditions, i.e. at pH 7.4;.pCO₂ 40mmHg and T 37°C, varies between 23.8 (± 0.8) mmHg for the horse, 25.0 (± 1.4) mmHg for cattle, 26.6 (± 1.2) for man and 28.8 (± 2.6) mmHg for the dog.
• 3.3. The higher dispersion of the dog's P50 is due to difference between breeds; in seven breeds investigated, the P50 ranges from 25.8 (spaniel) to 35.8 (hound).
• 4.4. We noted no sex difference in the four species.
• 5.5. The DPG level is confirmed to be low in cattle (< 1 μmol/gHb) as compared to man (13.5 ± 2.1 gmmol/gHb), horse (16.9 ± 1.1 gmmol/gHb) and dog (19.4 ± 2.8 μmol/gHb).
• 6.6. The oxygen exchange fraction defined as the difference in vol% between a pO₂ of 80 and 35 mmHg is, respectively, 3.6 (± 0.6) vol% for cattle, 4.0 (0.4) vol% for the horse, 5.5 (± 0.5) vol% for man and 6.6 (± 1.7) vol% for the dog.
• 7.7. The position and shape of the ODC, as well as T, DPG and pH effects, indicate that the haemoglobin of man and dog seem better adapted to O₂ delivery as compared to the horse and cattle.

     

Bioelectrical potentials across the mantle epithelium of Achatina fulica

• 1.1. The shell side of the mantle of Achatina fulica is several millivolts positive to the blood side in vitro.
• 2.2. The electrical potential does not depend on Na⁺, Ca²⁺, Mg²⁺, K⁺ or HCO₃⁻ but requires the presence of chloride on the shell side.
• 3.3. The potential difference and short-circuit current ranged from 3.0 to 30.0 mV and 15.0 to 75 μA/cm² with averages at 10m V and 50 μA/cm² respectively.
• 4.4. The electrical gradient is reduced by 2,4-dinitrophenol, thiocyanate and furosemide but not by ouabain, CO₂ or acetozolamide.
• 5.5. It is suggested that the nature and mechanism of electrogenesis in Achatina parallels that of the Helix mantle.

     

Body temperature in the mouse,hamster, and rat exposed to radiofrequency radiation: An interspecies comparison

• 1.1.|Colonic temperatures of BALB/c and CBA/J mice, golden hamsters, and Sprague-Dawley rats were taken immediately after exposure for 90 min to radiofrequency (RF) radiation.
• 2.2.|Exposures were made in 2450 MHz (mouse and hamster) or 600 MHz (rat) waveguide exposure systems while the dose rate, specific absorption rate (SAR), was continuously recorded. Experiments were performed on naive, unrestrained animals at ambient temperatures (T_a) of 20 and 30°C.
• 3.3.|Body mass and T_a) were found to be significant factors in influencing the threshold SAR for the elevation of colonic temperature. The threshold SARs at T_a's of 20 and 30°C were respectively: 27.5 and 12.1 W/kg for the BALB/c mouse; 40.7 and 8.5 W/kg for the CBA/J mouse; 8.7 and 0.61 W/kg for the golden hamster; and 1.58 and 0.4 W/kg for the Sprague-Dawley rat.
• 4.4.|The relationship between threshold SAR or SAR for a 1.0°C elevation in colonic temperature vs body mass were linearly and inversely related on a double logarithmic plot. The results of this study suggest that the thermoregulatory sensitivity to RF radiation in these rodent species is heavily dependent on body mass and T_a.

     

Comparative vitellin pattern and cladogenesis in Bacillus (insecta: Phasmatodea)

• 1.1. Under denaturing conditions (SDS-PAGE) the two natural vitellins of Bacillus taxa released five different polypeptides (A₁, A₂, A₃, B₁, B₂).
• 2.2. A₂ and B₂ bands from the two bisexual species (B. rossius and B. grandii) were found to differ; furthermore a non-vitellin yolk protein characterizes the subsepecies B.g. benazzii.
• 3.3. From gels and their densitometric scanning profiles it is clear that parental polypeptides are expressed in the thelytokous parthenogenetic hybrids (B. whitei, B. lynceorum) and in the hybridogenetic B. rossius-grandii benazzii.
• 4.4. A comparative approach of vitellin patterns appears fully adequate for tracing phylogenetic relationships and recognizing cladogenetic events.

     

Lipid components and utilization in consumers of a seagrass community: An indication of carbon source

• 1.1. The lipid components of three animals, the rock crab Nectocarcinus integrifons, the rock flathead Platycephalus laevigatus and the southern garfish Hyporhamphus melanochir, feeding in the seagrass beds at Corner Inlet, Victoria, Australia have been examined in detail in order to provide further information on seagrass community structure.
• 2.2. Biological marker compounds detected within animal gut content material were used to recognize dietary sources and then utilized by community members.
• 3.3. Both H. melanochir and N. integrifons have been shown to ingest and to varying degrees incorporate seagrass lipid material, thus further confirming the importance of seagrass carbon in the Corner Inlet environment.
• 4.4. The southern sea garfish H. melanochir is observed to remove C₁₈ PUFAs (polyunsaturated fatty acids) from ingested seagrass material.
• 5.5. Seagrass sterols are altered during incorporation into the lipids of this fish.
• 6.6. Lipid-rich digestive juices play a role in the digestive processes of all three animals.
• 7.7. Components tentatively identified as (NMI) (non-methylene interrupted) fatty acids have been detected in the lipids of the garfish H. melanochir and the crab N. integrifons.
• 8.8. The fecal material of all three animals represent possible sources of these lipids (NMI acids) in Corner Inlet sediments.
• 9.9. Based on lipid compositional data, N. integrifons feeds on Posidonia australis detritus and associated epiphyte material.
• 10.10. The removal of both plant and epibiota cellular lipids along the digestive tract of the crab was observed, although structural components such as long chain mono- and α,ω-dicarboxylic acids, which have been previously recognized as seagrass marker lipids are not directly absorbed.

     

A comparative study of the respiratory properties and physiological function of haemocyanin in two burrowing and two non-burrowing crustaceans

• 1.1. Oxygen dissociation curves were constructed for the haemolymph of two non-burrowing, Galathea strigosa and Eupagurus bernhardus, and two burrowing crustaceans, C. cassivelaunus and Nephrops norvegicus. The p₅₀ at in vivo pH values and 10°C was 12.6 Torr in G. strigosa, 23 Torr in E. bernhardus, 3.1 Torr in C. cassivelaunus and 11.5 Torr in N. norvegicus.
• 2.2. The Bohr values (Δlogp₅₀/ΔpH) were high in all species ranging between −0.96 and −1.48. Cooperativity expressed as P₅₀ averaged 3.3, 3.8 and 3.8 in G. strigosa, E. bernhardus and N. norvegicus. respectively. A lower value of 2.2 was observed in C. cassivelaunus.
• 3.3. The oxygen affinity of the haemocyanin was relatively temperature independent, the values for ΔH at pH7.9 ranging between −5.1 and −18.1 kJmol⁻¹.
• 4.4. Haemolymph respiratory gas analysis showed values similar to those previously reported in crustaceans: p_aO₂ ranging between 44 and 107 Torr and p_vO₂ values between 18 and 24 Torr.
• 5.5. Pre-/post-branchial pH differences were small in G. strigosa, E. bernhardus and N. Norvegicus, but averaged 0.09 of a pH unit in C. cassivelaunus. p_aCO₂ and P_vCO₂ values ranged between 1.4 and 2.3 Torr.
• 6.6. In buried C. cassivelaunus both pre- and post-branchial oxygen tensions decreased, as did oxygen tension overall during respiratory pauses.
• 7.7. Cardiac output values were low, ranging between 59 and 71 ml kg⁻¹ min⁻¹ for all four species and calculated stroke volumes were realistic in terms of animal size.
• 8.8. In the non-burrowing species physically dissolved oxygen accounted for 5–21% of the oxygen transported to the tissues. In the burrowing species values of 40–77% were found.

     

Metabolic responses of the mussels Perna viridis and Perna indica to declining oxygen tension at different salinities

• 1.1. Oxygen uptake and ammonia loss were monitored during responses to reductions of both salinity and oxygen tension (PO₂) in the marine mussels Perna viridis and Perna indica from southern India.
• 2.2. The proportional contribution of protein to total catabolic substrates under natural environmental conditions was as much as 96% in P. viridis, relative to only 19% in P. indica.
• 3.3. Normoxic oxygen consumption remained statistically unchanged in P. viridis conditioned to salinities between 32 and 15‰, with no obvious signs of distress. Although equally unaffected at salinities between 32 and 20‰, P. indica showed significantly reduced oxygen uptake following transfer from 32 to 15‰, and had died within the next 7 days.
• 4.4. At salinities greater than 20‰, P. viridis was better able than P. indica to regulate oxygen consumption independent of PO₂.
• 5.5. P. indica showed a compensatory increase in oxyregulatory capacity at 15‰. This exceeded unstressed abilities, helping to maintain albeit reduced oxygen uptake throughout wider ranges of PO₂.
• 6.6. Different responses recorded in each of these tropical and often intertidal species were in accordance with their natural distributions. Nevertheless, the oxyregulatory capacity in both species was higher than in bivalves from temperate and/or subtidally restricted habitats.

     

Mixed function oxidase activity in the harbour seal (Phoca vitulina) from sable is., N.S.

• 1.1. One adult male, eight pups (including two full term foetuses) and nine adult female harbour seals (Phoca vitulina) were analysed for indices of mixed function oxidase (MFO) activity.
• 2.2. MFO activity was present in liver samples, but was at or below detection limits in samples of kidney, lung and pancreas.
• 3.3. Hepatic ethoxyresorufin O-de-ethylase and benzo[a]pyrene hydroxylase activities were similar to those reported in other seals and in other mammals.
• 4.4. Cytochromes P-450 and b₅ concentrations were slightly lower than those observed in other mammals.
• 5.5. MFO activities in newborn pups and foetuses were significantly lower than those in adult females.
• 6.6. No qualitative differences in cytochrome P-450 isozyme distribution between foetal and adult samples could be discerned by electrophoresis.