The effect of incubation temperatuer on oxygen consumption and organ growth in domestic-fowl embryos

1. 1.|Oxygen consumption and organ growth were measured in domestic-fowl embryos incubated at different temperatures (36, 38 and 40°C).

2. 2.|Embryonic oxygen consumption was highest at an incubation temperature of 40°C and lowest at 36°C. These differences were ascribed largely to variations in embryo size at different incubation temperatures.

3. 3.|At incubation temperatuers of 40 and 38°C, there was a plateau in oxygen consumption late in incubation, but this was not apparent at 36°C.

4. 4.|At 36°C, some tissues (e.g. eyeballs) were “spared” the repression of growth that characterized the embryo as a whole, while other tissues (e.g. stomach) incurred a much greater growth reduction. Similarly, at 40°C, stomach growth exceeded that of the embryo as a whole, while the eyeballs were largely spared the enhanced growth.

5. 5.|A simple index of tissue age revealed that, in general, there were consensual changes in tissue maturity and growth at different temperatures but that there were some disparities between growth and maturity in individual organs.

Biosynthesis and properties of an extracellular metalloprotease from the Antarctic marine bacterium Sphingomonas paucimobilis

An extracellular protease from the marine bacterium Sphingomonas paucimobilis, strain 116, isolated from the stomach of Antarctic krill, Euphausia superba Dana, was purified and characterized. The excretion of protease was maximal at temperatures from 5 to 10°C, i.e. below the temperature optimum for the strain growth (15°C). The highly purified enzyme was a metalloprotease [sensivity to ethylenediaminetetraacetic acid (EDTA)] and showed maximal activity against proteins at 20–30°C and pH 6.5–7.0, and towards N-benzoyl-tyrosine ethyl ester (BzTyrOEt) at pH 8.0. At 0°C the enzyme retained as much as 47% of maximal activity in hydrolysis of urea denatured haemoglobin (Hb) (at pH 7.0), and at −5 and −10°C, 37 and 30%, respectively. The metalloprotease was stable up to 30°C for 15 min and up to 20°C for 60 min. These results indicate that the proteinase from S. paucimobilis 116 is a cold-adapted enzyme.     

Muscle potentials and temperature acclimation and acclimatization in flight muscles of workers and drones of Apis mellifera

1. 1.Muscle potentials in fibrillar flight muscles of worker and drone honeybees were recorded extracellularly at thoracic temperatures from 30 to 10°C.

2. 2.Extinction temperatures for muscle potentials were higher in drones for all treatments.

3. 3.Cold acclimation (15°C) lowered extinction temperatures significantly in workers and drones. Acclimitization changed extinction temperatures significantly only in drones.

4. 4.Cold acclimitization had a bigger effect on the rate of muscle potential amplitude decline with decreasing temperature than acclimation.

5. 5.Acclimation and acclimitization had no effect on the increase of muscle potential duration with falling temperature.

6. 6.Muscle potential frequency during shivering was not much different between cold and warm treated bees.

Acclimation to temperature and death at changing lethal temperatures in the freshwater fish Chalcalburnues chalcoides

1. 1.|In the freshwater fish Chalcalburnus chalcoides, an increase in the body (standard) size caused decreases in the upper LT-50 from 36.6° to 36.0°C and lower LT-50 from 6.3° to 5.3°C

2. 2.|The fish acclimated to constant temperatures between 10°C and 30°C showed reasonable heat acclimation and also reasonable cold acclimation. Thus, an increase in the acclimation temperature from 10°C to 30°C caused increases in the upper LT-50 from 34° to 36.2°C and the lower LT-50 from 1.25 to 6.5°C.

3. 3|The mean survival time — temperature curves of 10°, 20° and 30°C acclimated fish at various constant temperatures showed decreased in the survival tim ewith increasing lethal temperatures. Furthermore, an increase in the acclimation temperature causes a shift in the survival duration-temperature curve to the right, i.e., the fish become more heat resistant. Thus, the mean survival duration of 10°, 20° and 30°C acclimated fish at 35°C were 7.5, 79.6 and 530 minutes, respectively.

4. 4.|The effect of the thermal experience to changing lethal temperatures depends on the first lethal temperature to which the fish were exposed as well as the sequence of temperature changes. In the experiments in which the first lethal temperatures were between 32° and 34°C and the temperature was varied in an ascending order, their thermal resistance was increased and the fish required 114 to 174% of the expected lethal doses to die while in the experiments in which the starting temperature were between 38° and 40°C and the temperature varied in descending order, the fish become more sensitive to the upper lethal temperature and they died after receiving only 62 to 81% of the expected lethal doses. Thus, with a gradual increase in the lethal temperature, the fish show additional acclimation in the zone of resistance which in turn causes an increase in the thermal resistance. This may have ecological significance in nature.

Temperature dependence of delayed light emission in spinach chloroplasts

1. Delayed light of chlorophyll emitted at 0.1–3.9 ms after cessation of repetitive flash light was studied at temperatures between +40 and −196 °C in isolated spinach chloroplasts.

2. Induction kinetics of delayed light varied depending on temperature. It was found to be composed of two phases; one was an initial rapid rise followed by a rather fast decline to a low steady state level (fast phase), and the other was a slow increase after the initial rapid rise to the maximum followed by an insignificant slow decrease to a high steady state level (slow phase). The fast phase existed between −175 and 40 °C with the maximum at −40 °C, while the slow phase, between 0 and 40 °C with the maximum at 25 °C.

3. The intensity of delayed light at −175 °C was found to be less than one fiftieth that at 0 °C, and no delayed light emission was observed at −196 °C within experimental accuracy. This is in contrast to the results reported by Tollin, G., Fujimori, E. and Calvin, M. ((1958) Proc. Natl. Acad. Sci. U.S. 44, 1035–1047) in which the intensity of delayed light measured at −170 °C was about a half that at 0 °C.

4. The induction of delayed light measured at −96 °C was found to be significantly suppressed by the preillumination at −196 °C. This finding suggests that the primary photochemical event still survives at −196 °C without emission of delayed light.

5. Decay kinetics of delayed light after the flash excitation revealed the presence of at least two decay components. A slow decay component with a half decay time of several tens of milliseconds was observed at temperatures higher than 0 °C. A fast decay component with a half decay time of about 0.2 ms was observed at temperatures between −120 and 25 °C. The decay rate of this component was slightly retarded on cooling.

6. The System II particles derived from spinach chloroplasts with digitonin treatment showed a temperature dependence of delayed light similar to that of the chloroplasts. System I particles, on the other hand, scarcely emitted the delayed light at any temperature between 40 and −196 °C.     

Physical constraints on the foraging ecology of a predatory snail

We studied the effects of aerial exposure and high summer temperatures on the southern oyster drill ( Stramonita haemastoma ), feeding on the American oyster, Crassostrea virginica . In the laboratory, oyster drill feeding rates and growth were highest at 25 and 30°C, some mortality occurred at 35°C, all snails died at 40 and 45°C, and the 28-day LC 50 was 35.7°C. In a second experiment where both water temperature (25 vs . 33°C) and aerial exposure were varied, only simulated tidal exposure lowered oyster drill feeding and growth rates. In field cage experiments, oyster drills had reduced feeding rates and growth at intertidal sites, but snail growth rates increased in late summer with warmer water temperature. We therefore conclude that aerial exposure, not high temperature, is the major factor limiting oyster drill feeding and growth in intertidal oyster reefs. Field experiments with partial cages also suggested that ambient predation rates were much higher at a subtidal than at a nearby intertidal site. Because southern oyster drills have depressed feeding, growth, and possibly lower fitness in intertidal oyster reefs during the summer, this reduced predation risk may provide a refuge for intertidal oysters.     

Effects of temperature, photoperiod, and light intensity on the eclosion rhythm of the high-altitude Himalayan strain of Drosophila ananassae

Eclosion rhythm of the high-altitude Himalayan strain of Drosophila ananassae from Badrinath (altitude 5123 m) was temperature-dependent and at 21°C, it was entrained by cycles of 12 h light: 12 h darkness (LD 12:12) and free-ran in constant darkness, however, it was arrhythmic at 13°C or 17°C under identical experimental conditions (Khare, P. V., Barnabas, R. J., Kanojiya, M., Kulkarni, A. D., Joshi, D. S. (2002). Temperature dependent eclosion rhythmicity in the high altitude Himalayan strains of Drosophila ananassae. Chronobiol. Int. 19:1041-1052). The present studies were designed to see whether or not these strains could be entrained at 13°C, 17°C, and 21°C by two types of LD cycles in which the photoperiod at 100 lux intensity varied from 6 h to 18 h, and the light intensity of LD 14:10 cycles varied from 0.001 lux to 1000 lux. All LD cycles entrained this strain at 21°C but not at 13°C or 17°C. These results demonstrate that the entrainment of eclosion rhythm depends on the ambient temperature and not on the photoperiod or light intensity of LD cycles. Thus the temperature has taken precedence over the light in the entrainment process of eclosion rhythm of the high altitude Himalayan strain of D. ananassae. This may be the result of natural selection in response to the environmental temperature at Badrinath that resembles that of the sub-Arctic region but the photoperiod or light intensity are of the subtropical region.     

Temperature-dependent Development of Four Egg Parasitoid Trichogramma Species (Hymenoptera: Trichogrammatidae)

Trichogramma species have been successfully utilized for biocontrol of several lepidopteran pests worldwide. The development, survival and progeny production of two Kenyan species' Trichogramma bournieri Pintureau & Babault and Trichogramma sp. nr. mwanzai Schulten & Feijen (collected from Kenya), Trichogramma evanescens Westwood (Germany) and Trichogramma chilonis Ishii (India) was studied at four constant temperatures (13, 18, 25 and 34°C) with the 011 aim of assessing the relative biotic potential of the two native species for 011 biocontrol of Helicoverpa armigera and Plutella xylostella in Kenya. The study was conducted at the Institute 011 for Biological Control (BBA), Darmstadt, Germany. The Trichogramma species tested showed variations 011 in fertility, developmental time, percent emergence, progeny production and sex ratio 011 at the four temperature regimes. Fertility decreased as temperature increased from 25 to 34°C. 011 T. chilonis and T. evanescens completed development at all temperatures tested, but T. 011 bournieri and T. sp. nr. mwanzai failed to complete development at 13°C. The developmental 011 period for all the species decreased as the temperature increased. The duration of development from 011 oviposition to adult emergence varied from 8 days to 12 weeks shorter at 34°C than at 011 13°C for T. chilonis and T. evanescens . For the various temperatures tested, a linear model was 011 satisfactory for egg to adult development at P = 0.05 for T. chilonis and T. evanescens . The 011 lower temperature thresholds for development and duration in degree-days were 8.83°C and 188 for 011 T. chilonis and 9.23°C and 192 for T. evanescens , respectively. For all temperatures tested, 011 T. sp. nr. mwanzai had the highest preimaginal survivorship. Adult emergence was lower at 13°C and 34°C than at 011 18 and 25°C. The highest fertility (mean ±SE) (50.37 ±2.32 adult 011 female -1 ) and progeny production (44.03 ±2.02 adult female -1 ) was recorded at 25°C for 011 T. evanescens . Sex ratio was biased towards female at all temperatures in T. bournieri and T. chilonis . 011 At all temperatures tested, T . sp. nr. mwanzai produced more males than females. For all species tested, 011 favourable parasitism was between 18 and 25°C. The results from this study will be useful for mass rearing purposes as well as for future field release programmes.     

Thermoregulatory use of heat increment of feeding in the tawny owl (Strix aluco)

The heat increment of feeding (HIF) was investigated in the tawny owl (Strix aluco) in central Norway (63°N, 10°E), close to the northern limit of its distribution. HIF was measured as the increase in heat production (measured as oxygen consumption) after force-feeding the owls with laboratory mice at thermoneutral conditions (20 °C) and during cold-exposure (5 °C and −5 °C). The basal metabolic rate of the owls (mean mass 419 g) was 4.39 kJ h⁻¹ and the lower critical temperature was approximately 16 °C. During cold conditions, HIF substituted for thermogenesis, and at an ambient temperature of −5 °C the substitution was complete. Calculations indicate that the substitution by HIF may save the owls as much as 60% of their daily thermoregulatory costs. This corresponds to about 10% of their total daily energy budget.     

Finger temperatures during military field training at 0 to −29 °C

1. Skin and rectal temperatures were recorded continuously in 70 measurements during typical tasks of infantry and artillery training at 0 to −29 °C. The duration of the measurements varied from 55 min to 9.5 h.

2. The distribution of finger skin temperatures was quite similar at ambient temperature ranges 0 to −10 °C and −10 to −20 °C, while at −20 to −30 °C the finger temperatures were clearly lower.

3. At different ambient temperature ranges, 20–69% of finger temperatures were low enough to cause cold thermal sensations.

4. Sensation of cold was experienced at a finger temperature of 11.6±3.7 °C (mean±SD).     

Germination, Radial Growth, and Sporulation of Beauveria bassiana and Metarhizium anisopliae Isolates and Their Virulence to Chilo partellus (Lepidoptera: Pyralidae) at Different Temperatures

The effect of temperature regimes on conidia germination, radial growth and virulence of Beauveriabassiana and Metarhizium anisopliae against the spotted stalk borer Chilo partellus was investigated with Ethiopian isolates. Conidia germination, radial growth and sporulation of all isolates were retarded at 15 and 35°C. A suitable temperature range for the isolates was between 20 to 30°C. Conidia germination was less tolerant of low temperature (15°C) than radial growth. Radial growth and sporulation reacted differently to temperature. At both 25 and 30°C, all isolates induced 100% mortality to C. partellus larvae in six days. The LT₅₀ decreased for the isolates with increasing temperature.     

How to measure the thermal death of Daphnia? A comparison of different heat tests and effects of heat injury

1. 1. The thermal death point of the water flea Daphnia magna (age < 24 h, cultured at 20°C) varied considerably depending on the method used. The median lethal dose (LD₅₀), induced by an acute 24 h heat exposure was 34.8°C. It was 37.8°C following a thermal shock for 15 min, and it was 39.4°C when a continuous temperature increase (0.2°C/min) was used.

2. 2. Heat death temperature of daphnids was related to the acute heating rate.

3. 3. The logarithm of median lethal time (Lt₅₀) of daphnids, kept at a constant high temperature, had a linear relationship to temperature (°C) within the range of 28.0–38.5°C.

4. 4. The mortality after heat exposure increased with recovery time at 20°C for up to 3 days.

5. 5. The animals which survived the heat exposure produced eggs and offspring. Furthermore, no time lag in development between the control and heat exposure group was observed.

6. 6. The comparison of the results made by different heat tests categorized to Methods 1 and 2 by Precht (1973), for use in the determination of lethal limits of ectotherms, has been discussed.

     

Thermal sensations during simultaneous warming and cooling at theh forearm: A human psychophysical study

1. 1.The forearm of 5 female subjects ws thermally stimulated by 2 sets of interposed servo-thermodes that respectively drove skin temperature at ±0.1°C.s⁻¹ for 25 s and then held it constant. Mean skin temperature remained constant. The sequence was repeated at adapting temperatures between 22.5 and 37.5°C.

2. 2.Thermal sensations, continuously reported by the position of a dial, were warmer for heterogeneous thermal stimuli than for homogeneous stimuli when mean skin temperature was greater than 30°C and cooler when less than 27.5°C.

3. 3.This phenomenon is inconsistent with a single additive contribution of “warm” and “cold” information to thermal sensations.

Comparison of pinocytosis and phagocytosis in Acanthamoeba castellanii

Acanthamoeba, with high rates of phagocytosis and pinocytosis of the non-concentrative type, offers favorable experimental material for investigation of similarities and possible differences in these two modes of uptake. Phagocytosis was measured by the rate of uptake of latex beads and pinocytosis by the rate of uptake of radioactive inulin and albumin. The effects of the metabolic inhibitors NaN₃, NaCN, NaF, iodoacetate, 2,4-dinitrophenol and cold were found to be identical on both forms of endocytosis. Both endocytic processes were suppressed by inhibitors of aerobic metabolism and low temperature and were not appreciably affected by inhibitors of glycolysis. The cells recovered capacity to endocytose after exposure to all these compounds except 2,4-dinitrophenol, which was irreversibly toxic. Endocytosis and O₂ consumption were measured as a function of temperature. Below 5 °C both phagocytosis and pinocytosis ceased; between 9 and 15 °C uptake was less than 10% that at 29 °C. From 16 to 29 °C uptake was a linear function of temperature for both pinocytosis and phagocytosis. Curves for O₂ consumption and endocytosis both showed breaks at about 16 °C. Concanavalin A (ConA) inhibited both types of endocytosis more than 50% at concentrations as low as 5 μg/2 × 10⁵ cells/ml. Pinocytosis and phagocytosis were also measured simultaneously in the same cells. Increasing the rate of phagocytosis suppressed pinocytosis, but the combined volume of the two forms of uptake was essentially constant. In contrast, the estimated combined surface intake varied over a two-fold range. These data show no differences between phagocytosis and pinocytosis of the non-concentrative type, and suggest that control of the rate of endocytosis is determined by the volume of an internal compartment. The volume of this compartment, estimated by measuring the volume of latex beads that “saturate” the phagocytic mechanism, amounted to about 500 μm³/cell or roughly 15% of the cell volume.     

The effect of constant and changing temperatures on the thermal resistance of Lymnaea peregra (Müller)

The effect of constant and changing temperatures on both high and low lethal temperatures of Lymnaea peregra and the time course of acclimation were investigated. Snails acclimated to 6.5°, 11.5° and 16.5°C showed paradoxical ‘adaptation’ of their high letal temperature and reasonable ‘adaptation’ of the lowlethal temperature. This combination is thus observed for the first time in molluscs. Seasonal variation in the upper lethal temperature showed parallel changes and the snails became less resistant to heat during spring and summer. Acclimation to changing temperature conditions did not extend their temperature tolerance range. During the course of acclimation of 6.5°C snails to 16.5°C, about 70% of the acclimation was completed within the first 24 h and the rest was completed within 360 h at 16.5°C.     

The effects of constant and changing tempertures on the development of eggs of the freshwater snail Lymnaea auricularia (L.)

The rate of development of Lymnaea auricularia eggs was studied at various constant temperatures between 10° and 36°C. Development was accelerated as the temperature increased and at 36°C the eggs failed to develop. Spring eggs showed differences in their rate of development when compared with summer eggs when measured at similar tempertures.

Both spring and summer eggs were more than 90% fertile. Hatching success was high at temperatures between 10° and 30° (100%–82/9%); while at 34°C it was reduced to 60.6% for spring eggs. It was above 87% at temperatures between 10° and 34°C but it dropped to 62.3% at 36°C for summer eggs.

In one regularly changing temperature experiment a significant acceleration (P < .05) was found. In two others there was no significant difference beween predicted and observed egg durations. In one suddenly changing temperature regime (1 day at 20°, 1 day at 30° and so on) a huge retardation of development was found. In the other suddenly changing experiment (1 day at 15°, 1 day at 25°) no significant difference was found.

The exposure of eggs to extreme temperature (4°C, freezing and 4°C caused a retardation in the race of subsequent development of eggs at 25°C.     

Enzymatic and Non-Enzymatic Esterification of long Polyunsaturated Fatty Acids and Lysophosphatidylcholine in Isooctane

Phosphatidylcholine containing large amounts of long polyunsaturated fatty acid, eicosapentaenoic acid (C20:5) and docosahexaenoic acid (C22:6), was synthesized in isooctane. Immobilized phospholipase A₂ was used as a catalyst. A parallel non-enzymatic esterification reaction was investigated in separate experiments.

The concentrations of lyso-phosphatidylcholine, polyunsaturated fatty acids, water and the enzyme were varied over wide ranges as were the temperature and the reaction time. The type of enzyme, carrier and immobilization procedure were held constant.

The yield of phosphatidylcholine was relatively high (about 21%) when the concentration of polyunsaturated fatty acids was high (300 mg/g of reaction mixture) and the water content was low (below 30% of the dry immobilized enzyme). The highest yield of phosphatidylcholine was found at 80 hours and 75°C. However, at this temperature an extensive non-enzymatic reaction between polyunsaturated fatty acids and lyso-phosphatidylcholine occurred. At 80°C the polyunsaturated fatty acids were partly oxidized. Therefore, a temperature of 45°C to 65°C is probably the optimum temperature for the reaction.     

Temperature effects on evoked potentials of hippocampal slices from noncold-acclimated, cold-acclimated and hibernating hamsters

1. 1.|Neural activity was recorded in hippocampal slices from noncold-acclimated, cold-acclimated and hibernating hamsters.

2. 2.|Action potentials from a population of hippocampal pyramidal neurons were evoked by stimulating an afferent fiber tract, the Schaffer collaterals. The temperature of the artificial cerebrospinal fluid bathing the slice was varied by controlling the temperature of a water chamber jacketing the recording chamber.

3. 3.|The temperature just below that at which a population spike could be evoked, T_t, was 15.8 ± 0.9°C (mean ± SEM) for noncold-acclimated hamsters, 13.9 ± 0.3°C for cold-acclimated hamsters and 12.3 ± 0.3°C for hibernating hamsters.

4. 4.|These thresholds for evoked activity were significantly different in noncold-acclimated, cold-acclimated and hibernating hamsters, and may reflect acclimation of hippocampal neurons to cold.

Effect of temperature on the longevity of human fibroblasts in culture

The longevity of parallel cultures of the human diploid fibroblast strain MRC-5 was measured at various incubation temperatures. At 37°C the mean life-span was 57.2 passages, at 34°C it was 58.7 passages and at 40°C it was 29.2 passages. There was greater variation in longevity among cultures grown at 40°C than in the control population and least among those grown at 34°C. The decreased life-span at 40°C was probably due to accelerated ageing, as the transfer of senescent cultures back to 37°C did not lead to their recovery. Cultures grown at 32°C also had reduced life-span compared to the control, but this was probably not the result of ageing, as the transfer of cultures which had almost ceased growth back to 37°C allowed them to reach the normal life-span for this temperature. The results imply that clonal ageing is at least in part due to random events—possibly errors in protein synthesis—which occur more frequently with increasing temperature.     

The temperature dependence of the deformation of bone

The deformation characteristics of compact bone have been measured as a function of temperature in the range from −58 to 90°C. At temperatures below 25°C elastic, anelastic and plastic contributions to the strain could be distinguished. The Young's modulus increased as the temperature was reduced, while the nonelastic component was approximately independent of temperature. An interpretation of these results is made in terms of an idealised hydroxyapatite-collagen composite. At temperatures higher than 50°C the deformation was compounded by non-equilibrium recovery and an irreversible change in the structure of bone.