Oxygen consumption and torpor in the fat-tailed dwarf lemur (Cheirogaleus medius): Rethinking prosimian metabolism

• 1.1. Oxygen consumption was measured in a lemuriform prosimian, Cheirogaleus medius. throughout a 24-hr cycle. The standard metabolic rate was determined to be 0.95 ml O₂ (g · hr)⁻¹ agreeing well with the value predicted by allometric equations, 0.91 ml O₂ (g · hr)⁻¹.
• 2.2. As a group, prosimians are argued to have metabolic levels in agreement with eutherian norms, rather than hypometabolic levels as previously supposed.
• 3.3. Day length is shown to be an important behavioral cue for this species. Its complex yearly and daily torpor cycles are linked to this stimulus.

     

Metabolic and behavioral responses of American kestrels to food deprivation

• 1.1. The effect of short-term (79 hr) food deprivation at 27°C on body mass, locomotor activity, body temperature (T_b), and resting oxygen consumption was determined in eleven American kestrels (Falco sparverius).
• 2.2. The change in body mass during resting followed the relation, % mass remaining = 99 e^{0.07(days fasting)}. There was no significant difference in the rate of relative mass loss between males and females.
• 3.3. Locomotor activity, measured as perch hopping, was highly variable in both control and fasted birds and showed no correlation with stage of the fast, basal metabolic rate (BMR), or rate of mass loss during food deprivation.
• 4.4. Body temperatures of fasted birds declined continuously by 0.2–0.4°C per day from 39.3 to 38.3°C.
• 5.5. Both males and females responded to food deprivation with a decrease in metabolism. By the third night of fasting, BMR had declined 23.4% from 0.845 W (bird day)⁻¹ to 0.647 W (bird day)⁻¹. The observed reduction in BMR is 2.4 times that expected from a 1°C decline in T_b (assuming Q₁₀ = 2.5) indicating active suppression of metabolism.

     

The dynamics of the permeation of an analogue of insect juvenile hormone into nematodes

• 1.1. ¹⁴C-dichlorofarnesoate permeated rapidly into Haemonchus contortus (infective juveniles) and Panagrellus redivivus (mixed cultures) and was strongly bound by hydrophobic association (K_s > 10⁻⁴M).
• 2.2. Uptake rose linearly with increases in temperature (5–38°C) and external concentration (C₀; 0.07–2.15 × 10⁻⁴ M). Within 1 hr the internal concentration, C₁ was >C C₀.
• 3.3. The pH of the medium (6–8) did not affect uptake.
• 4.4. Efflux of dichlorofarnesoate was low: the half-time of release was > 18 hr.
• 5.5. The uptake curve approximated to the expression C₁/C₀ = a(1 − e^−bt) with a and b as constants and t in hr.
• 6.6. These results clarify previous work on the inhibitory action of juvenile hormone on the development of nematodes.

     

Light-induced transient increase of the activity of topoisomerase I in plasmodia of Physarum polycephalum

• 1.1. Activity of topoisomerase I and incorporation of [³H]uridine and [¹⁴C]thymidine were monitored during light-induced sporulation of the slime mold Physarum polycephalun.
• 2.2. A 4-fold transient increase of topoisomerase I activity but not of [³H]uridine or [¹⁴C]thymidine incorporation was observed after 42 hr of illumination with 6 hr impulses.
• 3.3. The activity of topoisomerase I did not increase in the absence of light impulses. However, ca 5-fold increase of the activity was observed in dark when 100 μ M dibutyryl-cAMP was administered 12 hr before harvesting of plasmodia.
• 4.4. Fluorodeoxyuridine and cycloheximide administered 36 hr after starting of the illumination cancelled the increase of the activity of topoisomerase I.
• 5.5. After 7 days of the illumination, when fruiting bodies appeared, the activity of topoisomerase I dropped to about 15% of the initial value.

     

The oxygen consumption rates of three gastrotrichs

• 1.1. The oxygen consumption rates for three sympatric species of marine gastrotrichs (anatomically similar, except that one contains hemoglobin) were measured with a Cartesian diver microrespirometer.
• 2.2. The rates for the two species without hemoglobin, Turbanella ocellata and Dolichodasys carolinensis, were 307.2 μl O₂ g⁻¹ hr⁻¹ and 108.0 μl O₂ g⁻¹ hr⁻¹, respectively, while the rate for the hemoglobin-containing species, Neodasys, was 208.9 μl O₂ g⁻¹ hr⁻¹.
• 3.3. The possession of hemoglobin by Neodasys (14% by volume) cannot be explained by an unusually high demand for oxygen.
• 4.4. Instead, the hemoglobin may be useful as an oxygen store providing continued aerobic metabolism in anoxic conditions, thus allowing Neodasys to exploit a different niche.

     

Metabolic responses of Cassin's Finches (Carpodacus cassinii) to temperature

• 1.1. The thermal neutral zone of Cassin's Finches extends from 22 to 37.5°C.
• 2.2. Standard metabolism (40.1 Wm⁻² or 7.6kcal bird⁻¹ day⁻¹) of the 28 g birds was 89% of the value predicted for passerines measured at night.
• 3.3. At temperatures below the zone of thermal neutrality metabolism is described by the relation, Wm⁻² = 1.55–74.5°C. The coefficient of heat transfer (1.55Wm⁻²°C⁻¹) is only 58% of the value predicted for birds of this size, indicating excellent insulation.
• 4.4. At temperatures above thermal neutralzfsity metabolism is described by the relation, Wm⁻² = 2.75–62.6°C.
• 5.5. Under conditions of heat stress (44.5°C; P_H2O = 8.6 Torr) Cassin's Finches were able to dissipate up to 208% of their metabolic heat production by evaporative water loss. Maximal rate of water loss was 56 mg g⁻¹ hr⁻¹.
• 6.6. At 20°C resting fasted finches lost a mean of 4.94 ± 1.5 SD mg H₂O g⁻¹hr⁻¹.

     

Reabsorption and accumulation of α-amino-iso-butyric acid in the nephridia of Sabella pavonina Sa vigny (Annelida polychaeta)

• 1.l. High amino acid concentrations were found in the anterior coelomic fluid of a Polychaeta (Sabella pavonina Savigny).
• 2.2. The concentrations being much higher in the fluid which penetrates the nephrostomia into the nephridia lumen than in the final urine indicates that the nephridia reabsorbs large amounts of amino acids.
• 3.3. Nephridial perfusion experiments showed that an amino acid analogue (α-amino-iso-butyric acid, AIB) is transported by the nephidia.
• 4.4. The transport took place across the nephridial wall owing to the presence of a carrier-mediated transport system and a diffusion system.
• 5.5. For the carrier-mediated transport, the V_max was 0.234 ± 0.025 nmol·min⁻ and the K_m 3.715 ± 0.315mmol·l⁻.
• 6.6. AIB accumulated in the nephridial cells up to a maximum rate of 01.17 nmol·min⁻.
• 7.7. Intracellular accumulation stopped increasing when the V_max for reabsorption was reached.
• 8.8. These results indicate that the carrier-mediated transport of AIB is located at the apical membrane of the nephridial cell, and that AIB transport by simple diffusion takes place through the paracellular pathway.

     

Respiration and energetics in west indian gorgonacea (Anthozoa,octocorallia)

• 1.1. The rates of oxygen consumption of five species of Gorgonacea were determined and their daily energy requirements for metabolism were estimated.
• 2.2. Oxygen consumption rates varied between 0.15 and 0.76 mg O₂ g organic matter⁻¹ hr⁻¹.
• 3.3. Daily energy requirements varied between 13 and 66 cal g organic matter⁻¹ d⁻¹.
• 4.4. Energy costs for maintenance were somewhat lower than in other reef-dwelling Anthozoa.

     

Time-dependent cadmium-neurotoxicity in rat brain synaptosomal plasma membranes

• 1.1. The modulation of lipid dynamics and lipid protein interactions were studied in rat brain synaptosomal plasma membranes (SPM) up to 24 hr after exposure to cadmium (Cd).
• 2.2. The activity of acetylcholinesterase and adenylate cyclase showed a considerable decrease after 6 hr of Cd exposure, followed by a progressive increase up to 24 hr.
• 3.3. SPM chemiluminescence showed a maximum decrease at 12 hr, demonstrating a considerable increase in lipid peroxidation.
• 4.4. SPM of Cd-exposed animals showed a statistical significant increase in fluorescence anisotropy parameter [(r₀/r) — 1]⁻¹ at 18 and 24 hr compared to SPM of the control, indicating a decrease of membrane fluidity.

     

Metabolic rates of Calathus melanocephalus (L.) (coleoptera,carabidae) from alpine and lowland habitats (jeløy and finse,norway and drenthe,the netherlands)

• 1.1. Metabolic rates (ml O₂/mg/hr) of three geographically separated populations of the carabid beetle Calathus melanocephalus L. (Finse and Je 10y, Norway and Drenthe, The Netherlands) were measured and compared by ANCOVA.
• 2.2. No significant relationship (P > 0.05) between metabolic rates and body weight or sex of the animals were found.
• 3.3. Individuals mostly acclimated to low temperatures by increased metabolic rates and in the opposite direction to higher temperatures. Individuals collected in early summer also showed higher metabolic rates than those caught later in the autumn.
• 4.4. Contradicting the theory of metabolic cold adaptation, beetles from The Netherlands had the highest metabolic rates, beetles from Finse intermediate rates and beetles from Jeløy the lowest rates.
• 5.5. No significant relation were found between geographical origin of the beetles and their respective chill-coma temperature.

     

Water fluxes and urine production in blue crabs (Callinectes sapidus) as a function of environmental salinity

• 1.1. Water efflux and urine production rates were measured in blue crabs acclimated to several salinities.
• 2.2. In 100% seawater the mean rate of water efflux (31.3 ml/100g hr⁻¹) was significantly greater than that in 50% seawater (18.9 ml/100 g hr⁻¹.
• 3.3. Water efflux was directly related to body weight.
• 4.4. The mean urine production rate was significantly greater in crabs acclimated to 50% and 30% seawater (0.17 and 0.18 ml/100g hr⁻¹) than in animals conditioned to 100% seawater (0.09 ml/100 g hr⁻¹).
• 5.5. The difference between theoretical net water fluxes for crabs exposed to 100% seawater and 50% seawater was similar to the difference in urine output in the same salinities, demonstrating the importance of the antennal gland in volume regulation.

     

Purification and properties of a β-1,4-xylanase from a cellulolytic extreme thermophile expressed in Escherichia coli

• 1.1. An endoxylanase (EC 3.2.1.8) was purified from an Escherichia coli strain carrying a xylanase gene from the extreme thermophile “Caldocellum saccharolyticum strain Tp8T6.3.3.1. It was found to have an M_r of 42,000 and an isoelectric point of approx. 5.0.
• 2.2. The enzyme showed optimum activity at pH 5.0–7.7 and had an activation energy of 44 kJ mol⁻¹. It was stable at room temperature at pH 4.5–11.5 in the presence of 0.5 mg ml⁻¹ bovine serum albumin. The half-life of the enzyme at 75°C was 20 min at pH 6.0 in the presence of 0.5 mg ml⁻¹ bovine serum albumin.
• 3.3. The xylanase had highest activity on oat spelts xylan, releasing xylobiose and some xylotriose. The K_m for oat spelts xylan was 0.021% (w/v) at pH6.0.
• 4.4. The enzyme had high activity on sugar cane bagasse hemicelluloses A and B, lower activity on larchwood xylan and also hydrolysed carboxymethylcellulose, 4-methylumbelliferyl β-D-cellobioside and p-nitrophenyl β-D-cellobioside, but could not hydrolyse xylobiose.
• 5.5. It showed transferase activity on p-nitrophenyl β-D-xylopyranoside. Xylose did not inhibit the enzyme.

     

The effect of salinity on coelomic fluid osmolyte concentration and intracellular water content in Luidia clathrata (Say) (Echinodermata: Asteroidea)

• 1.1. The concentrations (mM) of osmolytes in the coelomic fluid of Luidia clathrata kept at 25‰S seawater (control individuals) were: 345, Na⁺; 10, K⁺; 10, Ca²⁺; 44, Mg²⁺; 387, Cl⁻; 0.67, amino acids; 0.09, NH₄⁺.
• 2.2. When individuals were transferred from 25‰S to 15‰S or 35‰S, the concentrations of inorganic ions in the coelomic fluid usually equilibrated within 24hr and became the same as those in the medium.
• 3.3. The intracellular water content (g intracellular H₂O/g solute-free dry tissue) of the pyloric caeca and tube feet of control individuals throughout the experiment was 2.13 and 5.40, respectively.
• 4.4. In tissues of individuals transferred to 15‰S, the intracellular water content increased by an average 50% in 12 hr but returned to 19% above control levels during 1 week.
• 5.5. In tissues of individuals transferred to 35‰S, the intracellular water content decreased by an average 17% in 12 hr and did not change during 1 week.
• 6.6. Luidia clathrata is an osmoconformer and partial cell volume regulator within the seasonal salinity range it encounters.

     

Low metabolic rate in a nocturnal desert lizard,an arbylus switaki murphy (Sauria: Gekkonidae)

• 1.1. Metabolic rates were measured in two xeric-adapted gekkonid lizards, Anarbylus switaki sind Coleonyx variegatus.
• 2.2. Standard metabolic rates (SMR) were 0.074 ml O₂/g hr in A. switaki and were 70% of the value predicted on the basis of mass from regression equations. The SMR of 0.146ml O₂/ghr in C. variegatus is similar to the predicted value for a lizard of this mass.
• 3.3. During intense activity, metabolic rates of 0.378 and 0.804ml O₂/g hr were measured in A. switaki and C. variegatus, respectively.
• 4.4. Various theories to explain reduced SMR in lizards are discussed, and it is concluded that none is entirely satisfactory, and caution should be exercised in interpreting the adaptive significance of reduced SMR.

     

Laboratory studies on the oxygen consumption of the marine teleost,Lichia amia (Linnaeus, 1758)

• 1.1. The oxygen consumption of the marine teleost, Lichia amia was investigated under controlled laboratory conditions.
• 2.2. The routine oxygen consumption showed a strong circadian rhythm with the fish being mainly active during the light period.
• 3.3. The specific mass exponent (dimension: μg O₂/g/hr) is temperature independent and ranges from 0.27–0.29.
• 4.4. Starving the fish results in a mean decrease in active, routine and standard oxygen consumption of 21%, 24% and 20%, respectively.
• 5.5. Feecling led to an increase in the oxygen consumption of the teleosts, with the mean metabolic rate over the 24 hr that followed, being 58% and 50% higher for fish that had been starved for 162hr and 40 hr, respectively.
• 6.6. Apparent SDA showed some variation and ranged from 6.0 to 35.5%.
• 7.7. The results obtained are generally in agreement with those recorded for other teleosts.

     

Charge interactions of cytochrome c with cytochrome c oxidase

• 1.1. The pyridoxal phosphate (PLP) modification of the lysine amino groups in cytochrome c causes decrease in the reaction rate with cytochrome c oxidase.
• 2.2. The rate constants for (PLP);-cyt. c, PLP(Lys 86)-cyt. c, PLP(Lys 79)-cyt. c and native cytochrome c (at pH 7.4, 1=0.02) are 3.6 × 10⁻³'sec-', 5.5 × 10⁻³, 5.2 × 10⁻³-'sec⁻¹ and 9.8 × 10⁻³sec⁻¹, respectively.
• 3.3. In spite of the same positive charge of singly PLP-cytochromes c the reaction between PLP(Lys 86)-cyt. c and cyt. c oxidase exhibits the ionic strength dependence that differs from those of the PLP(Lys 79)-cyt. c.
• 4.4. The rate constants at zero and infinite ionic strength for PLP(Lys 86)-cyt. c is 2-fold less than that for PLP(Lys 79)-cyt. c.
• 5.5. The positively charged cytochrome c lysines 86 and 79 form two from four or five predicted complementary charge interactions with carboxyl groups on cytochrome c oxidase.

     

Effect of calcium ions on ecdysteroid secretion by testes of Heliothis virescens

• 1.1. Testes of Heliothis virescens synthesized ecdysteroid in media containing low titers of calcium; the optimum calcium titer for testis sheaths stimulated to synthesize ecdysteroid in vivo was ca 1 mM, while the optimum of testes stimulated in vitro with the peptide testis ecdysiotropin was ca 0.3 mM calcium.
• 2.2. Verapamil at concentrations lower than 10⁻³ M induced increases in ecdysteroid synthesis, indicating more efficient synthesis when calcium influx was inhibited.
• 3.3. Hemolymph of H. virescens was 7 mM in calcium, while whole testes were maintained at 1–2 μM calcium.

     

A halogenated amino acid-containing sperm activating peptide and its related peptides isolated from the egg jelly of sea urchins,Tripneustes gratilla,Pseudoboletia maculata,Strongylocentrotus nudus,Echinometra mathaei and Heterocentrotus mammillatus

• 1.1. Twenty-eight peptides were isolated from the egg jelly of sea urchins, Tripneustes gratilla, Pseudoboletia maculata, Strongylocentrotus nudus, Echinometra mathaei (type A and B) and Heterocentrotus mammillatus and their amino acid sequences were determined.
• 2.2. Two of the peptides obtained from T. gratilla egg jelly possessed a bromophenylalanine (Br-Phe) residue in their sequences (Gly-(Br-Phe)-Asn-Leu-Asn-Gly-Gly-Gly-Val-Gly and Gly-(Br-Phe)-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly).
• 3.3. All of the peptides elevated cyclic GMP concentrations in the spermatozoa of the respective sea urchin and caused a shift in the apparent mol. wt of a major sperm protein of the respective sea urchin.
• 4.4. They stimulated respiration rates of the spermatozoa of Hemicentrotus pulcherrimus as well as their own species.
• 5.5. One-half maximal concentrations of the peptides for respiratory stimulation of H. pulcherrimus spermatozoa were between 10⁻¹¹ M and 10⁻⁹ M except a methionine-containing peptide which was about 10⁻⁷ M.

     

Blood volume recovery in hemorrhaged japanese quail

• 1.1. Blood volume and plasma biochemical changes and feed and water consumption in response to a hemorrhage by phlebotomy of 30% of the calculated total blood volume with and without replacement of blood volume with physiological saline were determined in juvenile male Coturnix coturnix japonica.
• 2.2. Plasma protein and osmolality decreased rapidly posthemorrhage and did not recover by 72 hr posthemorrhage.
• 3.3. Plasma glucose, Na⁺ and K⁺ increased within Ihr postphlebotomy. Plasma Na⁺ returned to nonphlebotomized levels within 6 hr postphlebotomy.
• 4.4. Saline replacement of blood volume resulted in hypervolemia within 3–5 min postphlebotomy.
• 5.5. Phlebotomized quail receiving no saline recovered blood volume to 0 hr (nonphlebotomized) levels within l hr postphlebotomy.

     

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.