B2964 – Microcalorimetric study of the growth of Enterococcus faecalis in an enriched culture medium
Enterococcus faecalis is a Gram-positive bacteria, considered one of the most common causes of nosocomial infections. Bacterial cultures produce an exchange of energy as a result of the bacteria metabolisms. The rate of heat production is an adequate measure of the metabolic activity of the organisms and their constituent parts. Microorganisms produce small amounts of heat: 1–3 pW per cell. Although the heat produced by bacteria is very small, their exponential reproduction in a culture medium permits heat detection through microcalorimetry. In this
study, we analyzed the microcalorimetric behavior of Enterococcus faecalis. A thermal Calvet microcalorimeter was used. The inside of the calorimeter contains two stainless steel cells (experimental and reference). Experiments were carried out at final concentrations of 106,105,103, and 10 CFU/mL and a constant temperature of 309.65 K was maintained within the microcalorimeter. Recording the difference in calorific potential over time we obtained E. faecalis’s growth curves. Thermograms were analyzed mathematically allowing us to calculate the
constant growth, generation time and the amount of heat exchanged over the culture time.
B2854 – Effect of different fluorescent dyes on thermal stability of DNA and cell viability of the hyperthermophilic archaeon Aeropyrum pernix
The interactions of DNA-binding dyes (Hoechst 33258, DAPI, acridine orange) and DiBAC4(3) with hyperthermophilic archaeon Aeropyrum pernix cells were investigated by the combination of calorimetric, spectroscopic and microscopic techniques. All of the dyes, studied here, affect the thermal stability of DNA in vivo and in vitro. Hoechst 33258 is highly DNA-specific probe,
which does not affect the thermal transitions of other cellular components as can be detected by differential scanning calorimetry (DSC). Due to this unique property, it can be used as a potential DNA marker for in vivo DSC studies. The localization of the dyes in the cells and viability assay was revealed by fluorescence microscopy. Hoechst 33258, DAPI and acridine orange did not distinguish between viable and non-viable cells of Aeropyrum pernix. Only with the commercially available Live/Dead BacLightTM kit we were able to discriminate viable and
non-viable Aeropyrum pernix cells.
B2783 – Thermophysical properties of medium grain rough rice (LIDO cultivar) at medium and low temperatures
Bulk density, specific heat capacity, bulk thermal conductivity and bulk thermal diffusivity of medium-grain rough rice (LIDO cultivar) have been studied. Specific heat was determined by DSC, thermal conductivity by the probe method and bulk thermal conductivity indirectly from bulk density, specific heat capacity and bulk thermal conductivity. All the thermal properties have been determined at different moisture contents and temperatures used during cooling and storage operations and the effect of these variables has been investigated. It has been shown that moisture content has the greatest effect on specific heat and bulk thermal conductivity. Temperature also affected these thermal properties, but to a smaller extent. Mathematical expressions
have been developed to determine each of these thermophysical properties as a function of moisture content and temperature.
B2661 – Microcalorimetric study on the growth and metabolism of Pseudomonas aeruginosa
Microcalorimetry is an experimental technique which allows us to precisely measure the energy released as a consequence of any transformation process. All organisms produce heat as a consequence of metabolism. The rate of heat production is an adequate measurement of metabolic activity of organisms and their constituent parts, cells and sub-cellular levels. Microorganisms produce small amounts of heat, in the order of 1–3 pW per cell. Despite the low quantity of heat produced by bacteria, their exponential replication in culture medium allows their detection using microcalorimetry. This study is a microcalorimetric study of the growth and metabolism of the bacterium Pseudomonas aeruginosa, using the heat liberated
as a consequence of bacterial metabolism. With this aim, we used a Calvet microcalorimeter, inside which two Teflon screw-capped stainless steel cells were located (sample and reference). Experiments were carried out at final concentrations of 106, 105, 103 and 10 CFU/mL, and a constant temperature of 309.65 K was maintained within the microcalorimeter. Recording the difference in calorific potential over time we obtained P. aeruginosa’s growth curves. The shape of these curves is characteristic and has a single phase. Thus, the heat flow curves were mathematically studied to calculate the growth constant and generation time of this bacterium.
B2659 – Direct calorimetry of free-moving eels with manipulated thyroid status
In birds and mammals, the thyroid gland secretes the iodothyronine hormones of which tetraiodothyronine (T4) is less active than triiodothyronine (T3). The action of T3 and T4 is calorigenic and is involved in the control of metabolic rate. Across all vertebrates, thyroid hormones also play a major role in differentiation, development and growth. Although the fish thyroidal system has been researched extensively, its role in thermogenesis is unclear. In this study, we measured overall heat production to an accuracy of 0.1 mW by direct calorimetry in a free-moving European eel (Anguilla anguilla L.) with different thyroid status. Hyperthyroidism was induced by injection of T3 and T4, and hypothyroidism was induced with phenylthiourea. The results show for the first time at the organismal level, using direct calorimetry, that neither overall heat production nor overall oxygen consumption in eels is affected by
hyperthyroidism. Therefore, we conclude that the thermogenic metabolism-stimulating effect of thyroid hormones (TH) is not present with a cold-blooded fish species like the
European eel. This supports the concept that TH does not stimulate thermogenesis in poikilothermic species.
B2649 – Metabolic depression in fish measured by direct calorimetry: A review
In nature under adverse conditions like low oxygen conditions or starvation fish often lower their metabolism: ‘metabolic depression’. This strategy of lowering the metabolic rate is a survival strategy and is used to save energy stores and diminish end-product accumulation. The overall metabolic rate of animals can be deduced by measuring metabolic processes such as oxygen consumption, but the ultimate method is measuring heat flow. In this review, we will summarise the available data about metabolic depression measuring heat flow, i.e. by direct calorimetry in fishes, which were carried out almost exclusively with a 1-l flow through calorimeter. Using deconvolution techniques the time constant of this calorimeter was measured that allowed to estimate the time course of metabolic depression, which was found to take place on a time scale of 20–30 min. We demonstrated that metabolic depression is species dependent. Goldfish, eel and tilapia show metabolic depression under low oxygen conditions while this is not the case for common carp. In addition it is shown that metabolic depression is flexible and increases with decreasing oxygen availability. Furthermore using a video analysing system we demonstrated that metabolic depression is not caused by a reduction of external activity. As heart rate falls dramatically during metabolic depression as shown by small wireless transmitters, we hypothesise that blood flow reduction might be the proximate cause for metabolic depression.
B2603 – MicroDSC study of Staphylococcus epidermidis growth
A microcalorimetric study was carried out using a Staphylococcus epidermidis population to determine the reproducibility of bacterial growth and the variability of the results within certain experimental parameters (temperature, bacterial concentration, sample thermal history). Reproducibility tests were performed as series of experiments within the same conditions using either freshly prepared populations or samples kept in cold storage. In both cases, the samples were obtained by serial dilution from a concentrated TSB bacterial inoculum incubated overnight.
B2602 – Calorimetric detection of the toxic effect of androgens on fission yeast
Calorimetry is evaluated for study of the toxic effect of environmental androgens on Schizosaccharomyces pombe cells. The results indicate that androstendione, androstandiendione and dehydrotestosterone inhibited S. pombe heat production rate. Although, the turbidimetric method showed that testosterone (TS) had no influence on growth of S. pombe, calorimetry revealed that there was a shift in growth period in samples with TS
B2427 – The effect of solid-liquid effluents from anaerobic digesters on soil microbial activity. A calorimetric study
A calorimetric procedure is developed to study the effect on the soil of the effluents resulting for the anaerobic digestion of slaughtering houses residues. DSC was used to study the pyrolysis properties of the effluent and the soil while isothermal calorimetry is applied to study the microbial activity in the effluent and to assess on its effect on the microbial activity of the soil where the industrial digester will be situated. The calorimetric data were studied together with the chemical and biological properties of that residue. Results showed that effluent is constituted by low levels of carbon and high levels of nitrogen. The power–time curves of the effluent have the typical shape of microbial growth yielding microbial growth rate constants between 0.37 and 0.53 h–1 for about 4 and 11 h. The addition of the effluent to the soil decreases the heat of pyrolysis with time and stimulates the heat flow rate of the microbial metabolism.
B1633 – Energetics of honeybee development
Isoperibol and combustion calorimetric investigations
Energetics, growth and development of workers and drones of the European honeybee Apis mellifera carnica were determined by classical isoperibol Calvet calorimetry and by combustion bomb calorimetry during one breeding season. Development was followed from the moment of egg laying till to the hatching of young adults. Mass, heat production rate and specific heat production rate served as experimental parameters registered daily. Two worker and two drone larvae remained after capping for 2 weeks in the calorimeter to continuously monitor their metabolism, their locomotor activity, moulting and hatching. Drone mass and metabolism were significantly higher than those of workers in all states of development.
The energy content during the development of workers and drones was evaluated by combustion calorimetry and by CHN analyses combined with the Dulong equation or derivatives of it.
B1480 – Calorimetrical and biochemical investigations on the influence of the parasitic mite Varroa destructor on the development of honeybee brood
The parasitic mite Varroa destructor is a serious pest to the western honeybee Apis mellifera. Here, we investigated the impact of mite infestation on the energy content, energy density, hemolymph volume and hemolymph protein concentration of drone and worker pupae. Mite infestation had a significant impact on the energy content of worker pupae at the end of metamorphosis, with an energy content of highly infested pupae 15% lower than non-parasitized pupae. The energy content of infested and uninfested drone pupae did not differ significantly. The energy density of drones and workers was not affected by mite infestation. Drones had a higher energy density compared to workers and lost more energy during metamorphosis. The heat production rates of drone pupae did not change due to mite parasitation. The total hemolymph volume of worker bees was significantly reduced in infested pupae, whereas the mites did not influence the hemolymph protein concentration. Although drones generally were less affected through mite infestation than workers, our results reveal a clear energetic impact of mite parasitation on honeybee pupae.
B1473 – Calorimetric investigations on the action of alarm pheromones in the hornet Vespa crabro
This study investigated the effects of alarm pheromone components on the heat production rates of hornets (Vespa crabro) by means of direct calorimetry. In a flow-through system, pheromones from hornets, honeybees (Apis mellifera) and yellowjackets (Vespula vulgaris) were sucked through a measuring vessel containing a group of hornet workers. The locomotive reaction of hornet workers was recorded as an increase of the heat production rate. Hornets exhibited a strong response to their own alarm pheromone components, mainly 2-methyl-3-butene-2-ol (MBO). They also reacted intensively upon the main alarm pheromone component of the honey bee, isopentylactetate (IPA), but less pronounced to alarm pheromone components of yellowjackets. The metabolic response of hornets to MBO was dose-dependent. The heat production rates of provoked hornet workers were similar to those of flying hornets. (z)-9-Pentacosene, a substance which is believed to be a thermoregulative brood pheromone, induced no metabolic reaction.
B1471 – Effect of the bee glue (propolis) on the calorimetrically measured metabolic rate and metamorphosis of the greater wax moth Galleria mellonella
Among the moth pests of the honeybee, the greater wax moth Galleria mellonella (Lepidoptera: Pyralidae) causes the greatest damage, unless controlled at an early stage, because it feeds on wax, pollen, and cocoon of the bee larvae. This leads to the destruction of honeycomb and subsequent deterioration of weakened colonies. For controlling the pest, natural products are second to none, not least because the use of synthetic substances carries with it the problem of residues, which remain in the beehive to affect the bee products. This paper reports the results of calorimetric investigations on the effects of the bee natural insecticidal glue, propolis, on pupal metamorphosis and the metabolic rate of different larval instars.
Experiments were performed by batch calorimetry to record the heat flow rate of individual larvae/pupae before and after the treatment, which consisted of dipping L5, L6, and L7 instars in a graded series of different concentrations of ethanol-dissolved propolis for 30 s before blotting them. The heat production rates were then recorded for 6-7 h (short period experiment) or during the entire pupal metamorphosis (long period experiment).
The fifth larval instar (L5) showed higher sensitivity to propolis treatment than L6 and L7 whereby total mortality was obtained by 4% propolis for L5 and 8-10% for the latter. The higher sensitivity of L5 can be accounted for by the very high mass-specific metabolic rate and the thinner and more fragile cuticle, typical of early larval stages, allowing the free transit of nonpolar toxic substances from the surroundings after being easily disrupted by components of propolis.
The treatment of the late L7 stage with nonlethal doses of propolis shortened the duration of pupal metamorphosis significantly. An untreated larva required 6.8±0.8 days (mean±S.E.,n=5) between larval-pupal and pupal-adult ecdysis, whereas this time was shortened to 5.4±0.9 and 4.8±0.5 days after treatment with 1 and 2% propolis, respectively. Though all treated larvae went through larval-pupal ecdysis, 40 and 100% of those treated with 2 and 4% propolis, respectively, displayed abortion of pupal metamorphosis and died.
These results indicate that propolis is toxic at higher concentrations and an insect growth regulator at lower ones. The use of propolis in the control of G. mellonella and its subsequent occurrence in honeybee products such as honey and wax may not cause the problem of a toxic residue, as it is the natural component in the beehive.
B1411 – Microcalorimetric toxicity investigation of propolis on Tenebrio molitor L. (Coleoptera: Tenebrionidae)
Toxicity of propolis (bee glue) against the three developmental stages (larvae, pupae, and adults) of the yellow meal worm Tenebrio molitor L. was investigated calorimetrically after dipping the animals for 60 s in different concentrations of propolis dissolved in 55% ethanol. The reduction in the heat production rate due to treatment with different concentrations of propolis displayed similar patterns in the case of larvae and pupae with the mean heat production rate being lowered by more than 90% due to treatment with propolis concentration of >7.5%. In addition the power-time (p-t) curves after treatment became smoother, the extent of smoothing being dependent on the concentration of propolis. Treatment of the adults, however, even with 10% propolis resulted in the reduction of the mean heat production rate by only 28%, with lower concentrations of propolis having no considerable impact.
B1343 – Calorimetric investigations on metabolic rates and thermoregulation of sleeping honeybees (Apis Mellifera carnica)
Heat production rates of sleeping honeybees were determined at ambient temperatures between 20 and 35°C. They increased with temperature from 4.7 mW g-1 (S.D. 2.2 mW g-1) at 20°C (n=18) up to a value of 12.3 mW g-1 (S.D. 7.6 mW g-1 n=12) at 35°C. This indicates that honeybees behave ectothermicly during sleep. The preferred ambient temperatures for sleep were investigated in a temperature choice experiment. The highest number of sleeping bees were found at 28°C. Evaluation of sleep behaviour in an observation hive revealed that bees prefer the same ambient temperature of about 28°C under natural conditions. Honeybees save energy during sleep with an ectothermic behaviour, but do not reduce their metabolic rates as much as possible by choosing places in the beehive with the lowest temperature. Instead, they prefer places with moderate intermediate temperatures, probably in order to promote regenerative processes during sleep
B1321 – Energy metabolism of european (Apis Mellifera Carnica) and egyptian (A. M. Lamarckii) honeybees
Two geographical subspecies of the honeybee Apis mellifera, the European bee A. m. carnica and the Egyptian bee A. m. lamarckii, were investigated by direct calorimetry. Maximum, mean and minimum heat production rates were determined for groups of 6 bees as a function of temperature and daytime. Smaller Egyptian subspecies showed significantly higher mass specific metabolic rates than the European one. Maximum and mean heat production rates decreased exponentially with growing temperatures while the minimum values remained constant.
B1315 – Differential scanning calorimetry and hydrodynamic study of bacterial viruses – About possible heat effects in hermetically closed calorimetric vessels with free volume above the liquid
The phase transitions occurring in aqueous solutions of macromolecules and their complex structures (like order-disorder transitions in proteins or nucleic acids solutions) are usually accompanied by small changes in their specific partial volumes. If the quantity of these substances in the closed calorimetric vessels is relatively large (few mg) and if the phase transition is accompanied by a high change of specific partial volume (like in solution of bacteriophages), it is possible to detect some imaginary heat effects in the DSC calorimeters which have closed (sealed) vessels with free volume above the liquid.
B1314 – Differential scanning calorimetry and hydrodynamic study of bacterial viruses – Effect of solution conditions
This paper deals with the study of the V-group, family T-even, E. Coli bacteria phage (named unphage). According to electron microscopic pictures, the geometrical parameters of this phage are 750x560 Å (from head) and 900 Å (from tail).
Bacterial viruses genome - ds-DNA - expulsion from the phage capsid is induced by temperature and is not accompanied by heat effects (temperature interval 45-75°C). Thus the temperature induced ejection of genetic material from phages is predominantly entropic. ds-DNA output from the capsid increases the viscosity of the phage suspension at least 100 times. ds-DNA output from the capsid is accompanied by a significant change of partial volume. The disruption of 1 mg of phage produces V=1.3x10^(-9) m3 which corresponds to a volume increase of 200%. This produces exothermic heat effects in closed calorimetric cells, with free volume above the measured liquid.
The contraction of the tail of phage plays an important role in the injection, in the step where phage attaches the outer membrane of the host cell. The main factors of the DNA condensation and packaging in the virus head, and after its ejection through the hole with a diameter close to that of ds-DNA, are caused by the surrounding solution quality, so-called hydration forces between ds-DNA parallel packaged segments and more exactly by the difference of this parameter inside and outside the capsid of the phage.
B1224 – Calorimetric measurements of energy contents and heat production rates during development of the wax moth Galleria mellonella
Changes of the energy content of different developmental stages in the wax moth Galleria mellonella were investigated by means of combustion calorimetry. The energy content (Q) is highest in L7-larvae (2.94 kJ per individual), the last stage in Galleria ontogenesis which takes up food, and the specific energy content (q) is highest in adults (37.5 ± 2.4 kJ g-1) with fat as energy reserve. Galleria takes up no further food after pupation and in adult life. The energy reserve for metamorphosis and adult life can be calculated to 1.65 kJ per moth.
Heat production rates of wax moths from L7-instars until death of the adult were recorded continuously by means of long-time calorimetric experiments. Different develomental phases could be clearly distinguished in the calorimetric curves because larval instars, prepupae, pupal instars and adults each showed a specific pattern of heat production. Developmental events such as moultings could be observed with own characteristic patterns of heat production rates. Mean specific heat production rates ranged from 13.7 ± 3.3 mW g-1 during cocooning of the L7-instar, to 5.1 ± 1.3 mW g-1 (n = 6) in prepupae. Adults showed a circadian pattern of heat production with resting metabolic rates of 5.6 ± 2.3 and 10.4 ± 2.1 mW g-1 (n = 6) during periods of activity.
B1115 – Metabolic rate and level of activity determined in tilapia (Oreochromis mossambicus Peters) by direct and indirect calorimetry and videomonitoring.
In order to correlate the metabolic rate and locomotor activity level of fish, a calorimetric system (Sétaram GF 108) was supplemented with a video tracking and motion analysis system. The motion analysis system is based on digital image processing. Once every second, two images (with an interval of 120 ms) are digitized and subtracted. The difference between the two images is used as a measure of the animal's movement. The activity of different complex movements, like turning, accelerations, fin movements, and branchial ventilation, were thus quantified. The combination of motion analysis with calorimetry gave some interesting results. Firstly, during extreme hypoxia, tilapia does not become lethargic as has been described for the anoxia-tolerant crucian carp . The locomotor activity level during severe hypoxia corresponded to the locomotor activity level during normoxia in the restricted area of the calorimetric vessel. This implies that the calorimetrically determined reduction of the heat flux by 50% under these conditions can be ascribed to a reduction in the cellular energy metabolism - metabolic depression. Secondly, the metabolic rate under constant light conditions was elevated from 11-18%, and the animals showed strong fluctuations in the heat flux; periods of aerobic metabolism alternated with periods of anaerobic metabolism. This was in contrast to the experiments under constant dark conditions in which the metabolic rate was around the standard metabolic rate (SMR). Under the applied conditions, no correlation was observed between heat production measurements and locomotor activity. This may possibly be ascribed to the limited size of the calorimetric vessel in which the animals' metabolic rates were around SMR. The observed oscillations in metabolic rate under light conditions could be another disrupting factor; oscillations in the circulation and ventilation could be responsible for this phenomenon.
B1106 – Calorimetric experiments on social insects.
Direct calorimetric experiments on the social insects: honeybees, bumblebees and hornets are described as function of castes, age, number of animals in a group, temperature, sound generation, hibernation and influence of pheromones. Two honeybee subspecies, the European bee Apis mellifera carnica and the Egyptian bee Apis mellifera lamarckii, were compared calorimetrically in their energy metabolism which differed considerably in favour of the more alert Egyptian form.
B1071 – Direct calorimetry of aquatic animals : effects of the combination of acidification and hypoxia on the metabolic rate of fish
The results of acidification on the metabolic rate of tilapia (Oreochromis mossambicus Peters) were studied in a differential 1-liter flow-through microcalorimeter (Setaram GF 108). After three days at pH 7.6 at normoxic conditions, the pH was slowly reduced to pH 4.0 at an acidification rate of 3.6 pH units over 240 min. Acidification during normoxia had no significant effects on the heat production (), the oxygen consumption () and the oxycaloric equivalent. Further-more we investigated whether the combination of hypoxia and acidification works synergistically. Fish were exposed to a graded hypoxia load of respectively 40% air saturation (AS), 25% AS, 15% AS and 5% AS, 8 h per level, in combination with acidification at pH 4.0. No support for a synergism was found in this study. All tilapia survived severe hypoxia (5% AS) in combination with acidification (pH 4.0) due to a metabolic depression.
B1059 – Microbial growth and metabolism : Modelling and calorimetric characterization.
Microbial growth can be qualitatively described with the empirical Gompertz function. This, however, has no specific physical meaning and gives no information about the underlying biochemical activity. When used to fit the isothermal calorimetric traces obtained from microbial cultures, it is inadequate. A more satisfactory description comes from a kinetic model that can reproduce the plate count data, the isothermal calorimetric trace and the change in the metabolite concentration
B1050 – Calorimetric and biochemical studies on the effects of environmental hypoxia and chemicals on freshwater fish.
The aim of this study was to assess the acute, sublethal effects of chemicals on fish from freshwater habitats. To this end goldfish (Carassius auratus) were exposed for up to 48 h to 2,4-dinitrophenol at concentrations well below the LC50 (96 h). In some experiments, fish were exposed to 2,4-dinitrophenol plus hypoxia/anoxia as an additional metabolic stress in order to enhance the effects of the chemical. Microcalorimetry proved very sensitive for detecting metabolic changes induced by 2,4-dinitrophenol. At 6 mg . 1-1 (corresponding to 1/4 LC50) the chemical had no significant effects on behaviour, motor activity and ventilation frequency, whereas the heat flow rate was markedly increased. Zebrafish Brachydanio rerio were unable to tolerate severe hypoxia, whereas goldfish proved very tolerant of hypoxia/anoxia. In goldfish, hypoxia induced a marked decrease in heat production, to less than 30% of the normoxic rate. Postanoxic recovery after 3-7 h of anoxia was rapid and complete; it was characterised by a transient period of excess heat. 2,4-Dinitrophenol affected the rate of aerobic heat production. It had no significant effect during hypoxia/anoxia but it markedly increased the heat flow rate during postanoxic recovery. As an adaptation to anoxia, goldfish produce and excrete ethanol during anaerobiosis. This process was not affected by 2,4-dinitrophenol. Microcalorimetry appears to be a sensitive method to detect metabolic effects of environmental chemicals.
B1005 – Direct calorimetry of aquatic animals: automated and computerized data-acquisition system for simultaneous direct and indirect calorimetry
A system for computerized registration of heat production data and oxygen tension values of a differential 1 litre flow-through microcalorimeter (Setaram GF 108) is described. The linked values of oxygen concentration and heat production data were simultaneously stored on a computer. The aerobic and total heat production rates were thus measured of goldfish (Carassius auratus L.) during normoxia, hypoxia and anoxia exposure. Incidentally, a partial anaerobic response was observed in goldfish during normoxia. During severe hypoxia and anoxia, goldfish respond with a reduction of the metabolic rate and a strong increase of anaerobic heat production. From the linked oxygen consumption and heat production data, the oxycaloric equivalent was calculated.The described system enables us to study continuously the effects of environmental factors on the metabolic rate of aquatic organisms.
B0991 – Direct and indirect calorimetric investigations on some snakes
The energy metabolism of three species of snake (Coluber geomonensis, Coronella austriaca and Elaphe longissima) was investigated by polarography and direct calorimetry at 25°C. The snakes produced a mean specific heat of 0.61 mW g-1, a maximum of 0.94 mW g-1 during locomotory activities and a minimum of 0.45 mW g-1 during periods of rest. From simultaneous measurements of heat dissipation and oxygen consumption, calorimetric to respirometric ratios of 457, 637 and 309 kJ (mol O2)-1 for the three conditions were calculated.
B0990 – Hypoxia and anoxia in insects: microcalorimetric studies on two species (Locusta migratoria and Manduca sexta) showing different degrees of anoxia tolerance
Microcalorimetry was used to study the effects of graded hypoxia and anoxia on two species of insects that differ in their tolerance of anoxia. Locusts (Locusta migratoria) can survive an atmosphere of pure nitrogen for not more than 4 h (at room temperature), whereas hawk moths (Manduca sexta) can recover from more than 24 h of anoxia.o produce graded hypoxia, air and pure nitrogen were mixed and this mixture was passed through the cells of a twin calorimeter equipped with circulation cells. A gas flow containing 2% or more of oxygen had no significant effect on behaviour (as observed in parallel experiments using transparent cells) or heat flow rate. If oxygen content was reduced to 1% or less the effects of oxygen lack became conspicuous; at a "critical oxygen concentration" (between 2 and 1% oxygen) the animals became agitated; they hyperventilated and showed escape movements, which were followed by a loss of body posture and complete immobility within a few minutes.This behaviour was reflected by a distinct peak in heat flow rate followed by a precipitous decrease in heat flow below the normoxic rate. During graded hypoxia, the heat flow rate approached a new value which was correlated with the degree of hypoxia. Under strict anoxia, 5.3 ± 1.1% and 3.6 ± 1.8% of the normoxic heat flow rates were reached by Locusta and Manduca, respectively. Thus the two insect species reacted similarly with respect to behaviour and metabolic rate (as indicated by heat flow) to both graded hypoxia and anoxia. A striking difference between the species was seen, however, in the rate of heat flow during recovery from hypoxia or anoxia. Readmittance of air after an anoxic or hypoxic interval led to a rapid increase in heat flow above the normoxic rate, but the amount of "excess heat production" during recovery was much higher in Locusta than in Manduca. The difference in the amount of "excess heat production" during posthypoxic recovery could not be accounted for by differences in behaviour (muscular activity) or by the effect of ambient temperature.
B0989 – Calorimetric investigations on thermoregulation and growth of wax moth larvae Galleria mellonella
Laboratory cultures of larvae of the wax moth Galleria mellonella show drastically increased temperatures a few days after the start of cultures. To examine this phenomenon, we performed direct calorimetric measurements on isolated eggs and larvae of different larval stages. Fourth and fifth instar larvae have significantly increased mass-specific heat production rates (up to 160 mW g-1). These high heat production rates are obviously the reason for the increased temperatures in wax moth cultures. In addition to these results, larvae were reared successfully in the measuring chambers of the calorimeters in long-time experiments, and power-time curves were obtained continuously for the whole period of larval development (up to 40 days).
B0963 – Direct calorimetry of aquatic animals: dynamic response of biological processes
The theory of system identification was used to determine the time constant t of a 1 litre flow through differential calorimeter (Setaram GF 108) at a flow rate of 50 ml min-1. By numerical differentiation the impulse response function g(t), the time derivative of the step response f(t), was calculated. With the aid of the Prony method, the time constant a2 of the time-discrete system of the decimated dataset was calculated, giving a mean value of 0.7402 ± 0.0044 (n = 4). This value was converted to the time constant t of the time-continuous system, giving a value of 33.25 ± 0.65 min (n = 4). The description of the system agreed with a model for a first order process. For control of the time constant value, the step response f(t) and the impulse response g(t) signal were simulated from the original block diagram u(t) which gave a suitable fit. Via the technique of deconvolution, the datasets of a biological case study with goldfish (Carassius auratus L.) were desmeared to describe the dynamic responses of the biological processes in the calorimetric vessel with a much reduced time constant t. Finally, the timescale on which the process of metabolic depression takes place in this species during anaerobiosis was estimated to be several minutes.
B0931 – Calorimetric investigations around a royal hieroglyph
Honeybees ("bjt") and their products honey and wax played an important role in Ancient Egypt. The bee became the symbol of the Pharaoh of Lower Egypt and a royal hieroglyph. Honey and wax were used for many purposes in daily life, as votive offering or as salary.Microcalorimetric experiments on bees of various ages or occupations and different castes as well as social effects among them are presented. Calorimetric curves are investigated for temporal structures indicating locomotor activities of the animals. Moreover, adult animals of the domesticated "usual" European honey bee Apis mellifera carnica are compared with those of the (modern) Egyptian bee Apis mellifera lamarckii.Differential scanning calorimetry and combustion bomb calorimetry have been applied to pollen, to honeys of various origins (lime-tree, pine, rape) or of intended purposes (royal jelly, hoarded food), to propolis and to different types of beeswax (comb wax from various places in the stock, wax from uncapping, wax for queen cells and commercial waxes).
B0891 – Microbiological and calorimetric investigations on degraded marbles from the Cà d’Oro facade (Venice)
Microbiological, physicochemical and biochemical investigations were carried out on degraded marble samples from the Cà d'Oro facade (Venice) in order to verify the presence of biodeterioration agents. The aerobic heterotrophic bacteria (mean value 105 CF
B0886 – Metabolic rate and tolerance of anoxia : microcalorimetric and biochemical studies on vertebrates and insects
The acute effects of anoxia are dramatic in animals that have high standard metabolic rates. Mammals, for instance, suffer a loss of brain functions within seconds, whereas the behaviour of some lower vertebrates such as frogs appears little affected in t
B0885 – Calorimetric investigations of phenol degradation by pseudomonas putida
Cyclic and polycyclic aromatic hydrocarbons are among the most widespread contaminants in soils, because they are still used in large amounts. Although poisonous to many organisms, consortia of microorganisms or single species such as Pseudomonas have spe
B0844 – Wirkung von Hypoxie und Anoxie auf den Energiestoffwechsel und die Stoffwechselrate von Vertebraten und Evertebraten: Biochemische und mikrokalorimetrische untersuchungen
B0843 – Kalorimetrische Untersuchungen zur sozialen Thermogenese bei der Hornisse Vespa crabüro L. (Hymenoptera, Vespidae)
B0841 – Direkte und indirekte Kalorimetrie an insekten während Hypoxie, Anoxie und postanoxischer Erholung
B0832 – Protective modification of freeze stress in plant tissue
Arabinoxylan mucilages from cell walls of hardy winter cereal plants inhibit the initial growth of ice crystals. These polymers affect the kinetics of freezing by adhesion to ice through interfacial liquid. The energy of polymer hydration decreases the latent heat of freezing by reducing the activation energy of melting. The decrease is a measure of adhesion energy. Other hydrated substances including the plasmalemma also equilibrate with freezing by adhesive interactions. Adhesion can produce lethal stress by -10°C. The adhesive stress can be reduced to osmotic stress by release of solutes from the protoplasts into the intercellular space. The interfacial tension in winter cereal plants is reduced by hydrolysis of fructan to sugars
B0765 – A novel 1 liter flow-through calorimeter for heat production measurements on aquatic animals without stress
A special custom-made 1 liter differential flow-through calorimeter (Sétaram GF108) has been adapted for flow-through heat flux measurements of aquatic animals. The lower limit of detection in a 1 liter vessel is 0.1 mW, whereas the sensitivity shows a linear correlation with the flow velocity up to at least 60 ml min-1. By carefully choosing the conditions and allowing enough time for adaptation, it appears to be possible to obtain data from stress-free animals. In this way the heat production of aquatic animals as a measure of total metabolic activity can be determined under aerobic or anaerobic conditions.
During anoxia the heat production in goldfish falls to 30% of the nonnoxic level.
This apparatus is a major breakthrough in direct calorimetry of animals, owing to the constant conditions and to its advanced electronics.
B0764 – Calorimetric investigations of pollution by xenobiotics
Parts of a forest ecosystem (decayed matter, soil and small animals) were investigated calorimetrically for the influence of a typical organic pollutant. Pentachlorophenol (PCP), a ubiquitously applied pesticide, was chosen as a representative man-made xenobiotic. At all concentrations used, PCP produced a pronounced stimulation of the energy metabolism by up to 350%.
B0748 – Heat production of frogs under normoxic and hypoxic conditions : a microcalorimetric study using a gas flow system
Heat production of maIe frogs, &ma &emj3orar&r~ was measured in a microcaforimeter
through which a continuous flow of gas was passed fn order to generate constant
normoxic, hypoxic or anoxic conditions, The normoxic heat flow was 163 f 37 bW/g
body weight in frogs that had not been treated with curare and 149 + 69 pW/g in
animals Immobilized with curare. During anoxia, frogs, whether curarized or not,
decreased their heat production to about 25% of the respective normoxic control. In
graded hypoxia (10% to 3% 021, curarized frogs decreased their heat rate according to
the grade of hypoxia they were subjected to.
B0746 – Microcalorimetric investigations of microbial activities: decomposition of needle litter under laboratory conditions
Microcalorimetric experiments on litter degradation included in a forestal amelioration program are reported. Abolition of water limitation in needle litter induced a strong initial peak in heat evolution. This transitory activation is due to easily degradable substrates utilized equally well by fungi and bacteria as shown by the addition of selective inhibitors. Degradation proceeded in three phases of changing activity depending on individual additives (lime, ammonium chloride, cellulose). Addition of cellulose alone stimulated degradation while nitrogen supply had no significant effect. Addition of lime always reduced the degradation rate. Particularly in combination with nitrogen addition, lime strongly inhibited the microbial activity by a release of ammonia, total weight loss after seven months being also reduced. No physical reactions were found interfering with true metabolic heat production, thus proving the validity of the method.
B0720 – Pentachlorophenol – An environmental pollutant. Microcalorimetric investigations of an ecological model system.
The influence of pentachlorophenol (PCP) on components of an ecological system was determined calorimetrically. After exposure to PCP at concentrations up to 0.4 g/l there was a significant stimulation to as great as 400 % of the rate of heat production in litter, soil and earthworms as a typical animal for this biotope. Even with the highest concentrations used no inhibitory effects could be detected in the present investigation.
B0707 – Microcalorimetric investigations of the energy metabolism of honeybee workers, Apis mellifera carnica.
Heat production measurements were performed for individual workers of different age and for worker groups of the honeybee Apis mellifera carnica by means of a 100-ml-Calvet-calorimeter. Individual worker bees show a strong positive correlation of the weight specific heat production rate with age. Increasing numbers of workers together in a group reduce the heat production drastically, so that a group of 12 bees dissipate less heat than one isolated animal. Addition of a queen or of bee brood to a group of 6 workers lowers the heat output, too. These effects could be described as socially conditioned by the use of an endoscope or a microphone incorporated into the calorimetric vessel. Endoscopie observations have been performed in the visible and the infrared region of the spectrum.
B0677 – Microcalorimetric studies in mycotypha africana
Physiological activities of yeast and hyphal forms of the dimorphic fungus Mycotypha africana (Mucorales)were investigated by a microcalorimetric method. A special culture vessel with a gentle stirring system was developed, in which the fungus was cultivated under good aerobiosis. Very reproducible power-time-curves of the yeast form were obtained. The economy of substrate utilization in relation to growth decreased with increasing glucose concentration. The characteristic pattern of heat production in media with 0.5 and 1% glucose became less pronounced with 2 and 5% glucose. The addition of specific inhibitors led to strong deformations of the pattern, to retarded development and to a suppression of budding.
B0614 – Combination of calorimetry and endoscopy for monitoring locomotor activities of small animals
A combination of microcalorimetry and endoscopy is presented and its application to metabolic investigations of small animals is discussed. The endoscopic lighting introduces additional heat production rates of a few milliwatts that are constant under optimum conditions so that they result in base-line shifts. The set-up is tested with snails of low heat production rates. Some further applications after including an image intensifier tube of second or third generation are mentioned.
B0556 – Direct calorimetry on free swimming goldfish at different oxygen levels
Heat production and oxygen consumption of groups of fasting, dark acclimated free swimming
goldfish were measured at 20 ~ during normoxia and anoxia. For this purpose a special 1 liter
flow through microcalorimeter was constructed. It appeared that the normoxic values could be
established at any time 2 days after introduction of the fish into the calorimeter, 700 j/h/MW and
1.6 mmoles/h/MW respectively. The normoxic oxycalorific value of 20 kJ/l 02 indicates the use
of a mixed substrate for oxidation. During anoxia, heat production was reduced to 30% of the
normoxic level; 200 J/h/MW.
B0536 – Microcalorimetric investigations of the energy metabolism of some reptiles
Energy metabolism of 16 lacertide lizards and 12 snakes was investigated by means of two Calvet microcalorimeters. Heat production is compared with oxygen consumption, rendering a value near to the theoretical value (19.3 J/ml oxygen) predicted for food mainly composed of lipids and proteins. Electrical stimulation of some of the experimental lizards and snakes showed burst-off behaviour and a strong increase in anaerobic metabolism with a consequent compensation of the oxygen debt. The experiments are discussed in connection with the usual indirect calorimetry.
B0531 – Calorimetry of free swimming goldfish at normoxic and anoxic conditions
B0398 – Germination des spores de “geotrichum candium”
B0377 – Microcalorimetric investigations on mixed microbial cultures
B0358 – Energétique de croissance d’une moisissure
B0346 – Microcalorimetric investigations on the green Alga “Scenedesmus acutus”.
B0338 – Beitrag zum problem der energiemessung in aquatischen ökosystemen: Mikrokalorimetrische untersuchungen von planktonalgen