Heart rate and its cholinergic control in the sole (Solea vulgaris), acclimatized to different temperatures

• 1.1. The effects of thermal acclimatization at 10 and 24°C on heart rate were investigated on unrestrained soles (Solea vulgaris).
• 2.2. The sensitivity of heart rate to temperature changes induced by temperature acclimatization was higher in cold-acclimatized than in warm-acclimatized soles.
• 3.3. Heart rate of cold-acclimatized fish to temperature changes was not affected by blocking the vagal tone with atropine.
• 4.4. After atropine treatment the ability of heart rate to show thermal compensation decreased in warm-acclimatized soles.
• 5.5. It is suggested that the vagus nerve can function differently at different temperatures.

     

Changes in molecular species compositions of glycerophospholipids in Japanese oyster Crassostrea gigas (Thunberg) during frozen storage

• 1.1. Changes in molecular species composition of phosphatidylethanolamine and phosphatidylcholine in Japanese oyster were studied during storage at −20°C.
• 2.2. In alkenylacyl- and alkylacyl-glycerylphosphorylethanolamine (GPE) and -glycerylphosphorylcholine (GPC), the molecular species having combinations of relatively shorter alkenyl and alkyl chains on sn-1 positions and 20:5n-3 on sn-2 positions, were lost rapidly in comparison with those of the corresponding longer alkenyl and alkyl chains and 22:6n-3.
• 3.3. In the case of diacyl-GPE, more molecular species having combinations of chains with longer total carbons (TC) and more double bonds (DB) were lost, than those having chains with shorter TC and fewer DB. Changes in the molecular species of the diacyl-GPC were opposite to those of the diacyl-GPE.
• 4.4. The results obtained suggest that oxidations and/or enzymatic hydrolyses selectivey occurred on the molecular species of glycerophospholipids during frozen storage.

     

Effect of temperature and salinity on the oxygen consumption of laboratory produced Penaeus californiensis postlarvae

• 1.1. The oxygen consumption by P. californiensis postlarvae (mean wt = 0.38 g) was determined at five different temperatures and four salinities.
• 2.2. The O₂ in each chamber was recorded at 10 min intervals for 1 hr. The time course of oxygen depletion was independent of O₂ concentration down to 1.6 mg/l.
• 3.3. Oxygen consumption increased with temperature from 0.0045 mg/g/min at 19°C, to 0.0142 mg/g/min at 35°C. The thermal coefficient (Q₁₀) indicated a very high sensitivity of the postlarvae to temperature variations at 19–23°C.
• 4.4. The results show that oxygen consumption significantly depends on temperature (P < 0.001) while salinity has only a marginal effect.

     

Temperature acclimation in respiratory and cytochrome c oxidase activity in common carp (Cyprinus carpio)

• 1.1. Common carp (Cyprinus carpio) exposed to experimental temperatures of 12, 18, 24, 30 or 36°C for a 4-week period were used to investigate the effect of temperature acclimation on the frequency of opercular movement (FOM), growth and cytochrome c oxidase (CCO) activity in heart, liver and muscle.
• 2.2. An exponential relationship between FOM and temperature after the first week (10₁₀ =1.76) disappeared after the second week.
• 3.3. The initially high FOM at temperatures of 30 or 36°C and the low FOM at 18 or 12°C changed over 4 weeks to approach the FOM of fish at 24°C.
• 4.4. This change in the relationship of FOM to temperature from highly dependent to independent appeared to be thermal compensation.
• 5.5. Heart and liver CCO activities were significantly affected by temperature, with the lowest activity at the approximate optimum temperature for growth, 24°C.
• 6.6. Highest CCO activities for heart and liver occurred at both the highest and lowest temperatures.
• 7.7. Among the three tissues, heart CCO activity was generally the highest and most affected by acclimation temperature.
• 8.8. Muscle tissue had the lowest CCO activity and was unaffected by temperature.
• 9.9. The high CCO activity at a cold acclimation of temperature 12°C was probably due to thermal compensation and the high activity at 36°C may have been a result of thermal stress.

     

Ultrastructure of maturing fish (Oreochromis niloticus) and snake (Waglerophis merremii) erythroid cells with regard to hemoglobin biosynthesis

• 1.1. Fish and snake immature erythrocytes were submitted to a comparative ultrastructural study, analysing changes in organelles involved in hemoglobin (Hb) biosynthesis.
• 2.2. Iron uptake occurs probably via transferrin, and ferruginous compounds accumulate as siderosomes, taken as iron sources for heme biosynthesis, later on caught by a double lamella.
• 3.3. Mitochondrial membrane of the inner camera differentiates to lamellated bodies that, sucessively, give rise to expansions for ferruginous material and globin chains captation, constituting prehemosomal vesicles, which become condensed vesicles, followed by prohemosomes.
• 4.4. Through an internal membrane rearrangement, prohemosomes change to hemosomes wherein, hypothetically, heme and the globin chains assembly may occur.
• 5.5. In both fish and snake erythroid cells, all stages for hemosomegenesis are similar to the stages found in erythroid cells of other vertebrate species, including humans, except that fish cells often present single organelles of still unknown function, void of internal membrane.
• 6.6. Through electrophoresis of the respective supernatants obtained after osmotical lysis of the organellar fractions, it was shown that fish hemosomes contain three Hb patterns, while snake hemosomes present two patterns.

     

O2-binding by the blood of the landhopper,Arcitalitrus dorrieni (Hunt) (Crustacea: Amphipoda)

• 1.1. The O₂-binding characteristics of the blood of the euterrestrial amphipod (landhopper) Arcitalitrus dorrieni have been studied.
• 2.2. The blood exhibited a low O₂ affinity, with a p₅₀ (at pH = 7.8) of 21.4 torr (10°C). Affinity decreased with an increase in temperature at constant pH (ΔH = − 79.4kJ/mol) but the Bohr factor (ΔlogP₅₀/Δ pH = −0.67) was unaffected.
• 3.3. The O₂-carrying capacity of the blood was moderate (1.51 ml/100 ml)
• 4.4. The results support the hypothesis that the blood of terrestrial amphipods is characterized by having a low affinity pigment.

     

Genetic variability in south african blue wildebeest (Connochaetes taurinus)

• 1.1. We used protein gel-electrophoresis to investigate genetic heterogeneity at 33 protein coding loci in a total of 46 blue wildebeest (C. taurinus) kept under different management regimes.
• 2.2. Average heterozygosity ranged from 2.14 to 4.3% and within-population differences accounted for 97.2% of total relative gene diversity.
• 3.3. Comparatively little divergence was found between animals sampled from populations with very diverse population sizes and management histories, with the largest genetic distance estimated between any two populations being only 0.0021.
• 4.4. We discuss our results with particular emphasis on the influence of management history on genetic diversity and divergence in C. taurinus.

     

Biology of cave crickets,Hadenoecus subterraneus,and camel crickets,Ceuthophilus stygius (Insecta: Orthoptera): Metabolism and water economies related to size and temperature

• 1.1. Metabolic rate (MR) and water budget (WB) components of cave and camel crickets are directly related to size and temperature.
• 2.2. MR increases most rapidly with size for insects in general followed by cave crickets (females > males), and lastly, camel crickets (no sex differences).
• 3.3. Metabolic thermal sensitivity of cave crickets (males > females) is much greater than camel crickets.
• 4.4. WB components parallel MR relations.

     

A test of the thermal coadaptation hypothesis with black rat snakes (Elaphe obsoleta) and northern water snakes (Nerodia sipedon)

• 1.The thermal coadaptation hypothesis predicts that (1) ectotherms experiencing a narrow range of body temperatures in the wild will evolve to perform well over a narrow range of body temperatures and that (2) the optimal temperature for performance will be equal to the preferred body temperature of the species.
• 2.We tested the predictions of the thermal coadaptation hypothesis with black rat snakes (Elaphe obsoleta) and northern water snakes (Nerodia sipedon) because black rat snakes experience lower and more variable body temperatures than northern water snakes at our study site.
• 3.We measured swimming speed, tongue-flicking speed, and striking speed in black rat snakes, and swimming speed and tongue-flicking speed in northern water snakes.
• 4.Adult water snakes generally had narrower performance breadths and higher optimum performance temperatures than adult black rat snakes.
• 5.Performance breadths were the same for swimming, tongue flicking, and striking within adult black rat snakes, but performance optima for these behaviours differed significantly. Performance breadths differed and performance optima were the same for swimming and tongue flicking within adult northern water snakes.
• 6.The relative swimming performance of neonates of the two species was similar in breadth to that of adults, but the thermal optimum for neonate black rat snakes was higher than that of adults.
• 7.Overall, our results provided support for the thermal coadaptation hypothesis.

     

Transfer system of cobalamin from pellicle to cytosolic binding proteins in Euglena gracilis

• 1.1. A cobalamin (Cb1)-transfer system from the pellicle to cytosolic Cb1-binding proteins occurs in Euglena gracilis.
• 2.2. The Cbl-transfer activity showed thermal dependency. The optimum temperature was 50°C. The Cbl-transfer activity was increased significantly above pH 7.0.
• 3.3. ATPase, thiol-groups and metal ions were not involved in the Cbl transfer.

     

Ionic currents of an identifiable giant neurone,d-rpln,of an african giant snail (Achatina fulica férussac), measured under voltage clamping—i. inward currents

• 1.1. The ionic currents of d-RPLN (dorsal-right parietal large neurone), one of the largest neurones identified in the suboesophageal ganglia of an African giant snail (Achalina fulica Ferussac), were measured under voltage clamping.
• 2.2. The present study concerns the inward currents. The electrical properties of the d-RPLN neuromembrane were: −57.8 ± 0.84 mV for the resting membrane potential (N = 79) expressed as M ± SE,
• 3.2.57 ± 0.13 MΩ for the membrane resistance (N = 12) and 48.85 ± 2.96 nF for the membrane capacitance (N = 12).
• 4.3. The maximal peak values of the inward currents in the physiological state, obtained at the command voltage (Vc)= −10mV, were: −1.02±0.06μA at the holding voltage (Vh) = −50mV and −0.98 ± 0.06 μA. at Vh = −60 mV. The peak time values of the currents at Vc = −10 mV were about 3–4 msec.
• 5.4. The outward current blocking agents, quinine (Q), at a concentration of 1.0 mM, reduced the peak inward current values and delayed their peak time, whereas tetraethylammonium chloride (TEA) at 25.0 mM and 4-aminopyridine (4-AP) at 5.0 mM were quite ineffective. Q at 0.25 mM hardly affected the same currents at all.
• 6.5. With the perfusion of the solution containing TEA at 25 mM, 4-AP at 5 mM and Q at 0.25 mM, the outward currents were reduced so that they are much smaller; the maximal peak values of calcium current (Ica), sodium current (Ina) and total inward current (Iin), which would be the sum of Ica and Ina (all were N = 4), obtained at Vc = −10 mV, were: −0.92 ± 0.05 μA for Ica, −0.30 ± 0.03 μA for Ina and −1.27±0.17μA for Iin.
• 7.6. The ratio of the maximal peak values of Ica and Ina of the neurone was about 3 to 1.
• 8.7. Tetrodotoxin at 0.1 mM completely blocked Ina of d-RPLN, whereas this substance at the same concentration had no effect on Ica.

     

A relationship between circulating natural glucocorticoids and the mechanical responses of the heart in atricial and precocial rodents

• 1.1. A comparison was made of the mechanical performance of heart muscle from mouse, an atricial mammal, with corticosterone as glucocorticoid and spiny mouse (Acomys cahirinus), a precocial mammal, with cortisol as glucocorticoid.
• 2.2. Force-frequency responses were negative in mouse and positive in spiny mouse.
• 3.3. During recovery, there was a gradual increase and an overshoot in the mouse, while in the spiny mouse there was an initial enhanced response, diminishing gradually with time.
• 4.4. High calcium concentration inhibited contractile tension in mouse heart, while it was positively inotropic in spiny mouse heart. Changes in the concentration of calcium did not change the patterns of force-frequency response.
• 5.5. Lowering the experimental temperature increased the time course and amplitude of the tension curve. However, various parameters exhibited different temperature sensitivity.
• 6.6. There was a significant difference in the levels of circulating cortisol between male and female spiny mice.
• 7.7. It is proposed that the differences in the mechanical responses of mouse and spiny mouse hearts may be explained in terms of the effects of the specific glucocorticoid hormone on the development of the sodium-calcium exchanger.

     

Behavior of the terrestrial nocturnal lizards Goniurosaurus kuroiwae kuroiwae and Eublepharis macularius (Reptilia: Eublepharidae) in a thigmothermal gradient

• 1.Two eublepharid gecko species were tested for their thermal preferences in a thigmothermal gradient.
• 2.Goniurosaurus kuroiwae kuroiwae from a humid subtropical Oriental forest selected a lower body temperature (Tp; average 16.6 °C) than Eublepharis macularius from an arid Palaearctic area (25.8 °C).
• 3.Both the locations of animals along the gradient and the Tp were significantly more variable among G. k. kuroiwae than among E. macularius.
• 4.There were no significant differences in Tp and in its variance between photophase and scotophase in either species.

     

Diurnal temperature sensitivity of dairy cattle in a naturally cycling environment

• 1.1.|Vaginal temperatures of 15 Bos taurus cattle were monitored for 17 days in daily pens exposed to normal environmental fluctuations.
• 2.2.|Regressions of vaginal temperature on ambient temperature were made for each collection time in the 24 h cycle. Slopes of regressions provided an index of animal sensitivity to environmental temperature.
• 3.3.|Fluctuations in sensitivity occurred throughout the day with positive slopes excepts at 0630 h.

     

Effects of acclimation temperature,season, and time of day on the critical thermal maxima and minima of the crayfish Orconectes rusticus

• 1.1. The critical thermal minima (CTMin) and maxima (CTMax) were determined for field-acclimatized and laboratory-acclimated crayfish (Orconectes rusticus) throughout 1984.
• 2.2. The CTMin and CTMax of field-acclimatized crayfish were seasonally adjusted by 9.7 C and 14.7 C respectively.
• 3.3. Seasonal variation in both tolerance regimes persisted in crayfish acclimated in the laboratory at 5 and 25°C for one week; however, no diel variation existed in either the CTMin or CTMax of laboratory-acclimated crayfish.
• 4.4. Integration of thermal acclimation of the CTMin and CTMax with seasonal conditioning may influence the functional capacities of this species when considered in relation to the seasonal ranges in stream temperature.

     

Cold tolerance of steinernematid and heterorhabditid nematodes

• 1.1. Nematodes survive subzero temperatures using either a freeze-avoiding or freezing-tolerant strategy. Steinernema anomali, S. feltiae, and Heterorhabditis bacteriophora were all found to be freezing tolerant.
• 2.2. The lower lethal temperatures were −22, −19 and −14°C for S. feltiae, H. bacteriophora and S. anomali, respectively.
• 3.3. Survival after prolonged freezing at −4°C was 6, 5 and 3 days for S. feltiae, H. bacteriophora and S. anomali, respectively.
• 4.4. Acclimation to lower temperatures increased freezing tolerance. The freezing tolerance of Heterorhabditis bacteriophora increased under a stepwise acclimation regime; S. feltiae acclimated better under a direct acclimation regime.

     

Identification of essential amino acids in the active center of thyroidal NAD+ glycohydrolase

• 1.1. Purified thyroidal NAD⁺ glycohydrolase has been subjected to the action of a number of group specific reagents in order to gain information concerning its mode of action.
• 2.2. Modification of histidyl residues with diethylpyrocarbonate strongly suppresses the NAD⁺ glycohydrolase activity. Inactivation with this reagent can be reversed to some extent by subsequent treatment with hydroxylamine.
• 3.3. NAD⁺ and ADP-ribose partially protect against inactivation with similar efficiencies.
• 4.4. The incomplete reactivation with hydroxylamine after diethylpyrocarbonate treatment and the selective inactivation by 2,4-pentanedione indicates that apart from one or more essential histidyl residue(s) also lysyl residues are important for activity. NAD⁺ and to a smaller extent ADP-ribose again protect against inactivation by 2,4-pentanedione.
• 5.5. The sensitivity of the enzyme towards N-ethyl-5-phenyl-isooxazolium-3'-sulfonate further points to the importance of carboxylate containing side chains.
• 6.6. The mechanistic implications of these results are discussed.

     

Heating and cooling rates of eastern diamondback rattlesnakes,Crotalus adamanteus

• 1.Establishing if and how organisms modulate temperature changes is an important component of understanding their thermal biology.
• 2.We used temperature-sensitive radio-transmitters to monitor heating and cooling rates between 5 and 35 °C of four Crotalus adamanteus in the laboratory.
• 3.We found no difference between heating and cooling rates in C. adamanteus. Additionally, rates of temperature change mirrored those of a biophysical model, further suggesting a lack of physiological thermoregulation.
• 4.Our findings contrast previously published studies that demonstrate active temperature control of similarly sized reptiles and demonstrate a need for more investigations of physiological thermoregulation in reptiles.

     

Hyaluronidase degradation of hyaluronic acid from different sources: Influence of the hydrolysis conditions on the production and the relative proportions of tetra- and hexasaccharide produced

• 1.1. Hyaluronic acid (HA) can be digested with a Streptomyces hyaluronidase.
• 2.2. The rate of production and the ratio of tetrasaccharide (T) and hexasaccharide (H), studied by HPLC, varied with the temperature and duration of hydrolysis.
• 3.3. The rates of production and the respective amounts of the two oligosaccharides depended on the rheological properties of the HA from different sources.
• 4.4. A close relationship was found between the initial rate of hydrolysis and the intrinsic viscosity of the HA (η_i).
• 5.5. Our data suggest that enzymatic degradation at a given pH value, temperature, and duration of hydrolysis is dependent on the conformation of HA.
• 6.6. Moreover, under given conditions, the relative proportions of the two oligosaccharides depend on the η_i and may also reflect the degree of hydrolysis of the substrate.

     

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.