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  • 1
    Electronic Resource
    Electronic Resource
    Experimental data on the energetic flux during glycolytic oscillations in yeast extracts (1995)
    Springer
    Cellular and molecular life sciences 51 (1995), S. 117-120 
    Details
    ISSN: 1420-9071
    Keywords: Calorimetry ; heat ; glycolysis ; oscillatory metabolism ; glyceraldehydephosphate dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Calorimetric experiments were performed on yeast extracts in which glycolytic oscillations were occurring. High metabolic fluxes coincided with low amplitudes and with high frequencies in a temperature range from 283 to 303 K, yielding an activation energy ofE a=76.8 kJ mol−1 and a mean Q10 value of 2.5±0.4. The calorimetrically determined reaction enthalpy ΔfH0, of the glycolytic catabolism of glucose revealed two distinct groups of extract preparations, with no intermediate values. The values were −107.5±28.7 kJ mol−1 and −30.8±5.7 kJmol−1, respectively, while −100.0 kJ mol−1 was predicted from theoretical calculations. Kreuzberg and Betz6 predicted rate limiting effects of GAPDH in oscillating extracts. However, when possible effects of GAPDH on frequency, number of oscillations or total heat production were examined, no influence of increasing or reducing the initial GAPDH concentration could be found. The results are discussed with reference to existing models of glycolytic oscillations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01929352
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Experimental investigation of the bound dissipation function (1975)
    Springer
    Archives of microbiology 105 (1975), S. 13-16 
    Details
    ISSN: 1432-072X
    Keywords: Irreversible Thermodynamics ; Energy Metabolism ; Calorimetry ; Yeast ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By means of a microcalorimeter (direct calorimetry) and a Warburg-apparatus (indirect calorimetry) that part of the dissipation of a growing culture of yeast cells which remains irreversible in the cells is determined (Ψ u ). The course of the Ψ u -function with time correlates with the increase of the specific cell concentration being conditioned by the growth phase of the culture but similar for fermentative and respirative metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447105
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Calorimetric investigations of the different castes of honey bees, Apis mellifera carnica (1992)
    Springer
    Journal of comparative physiology 162 (1992), S. 119-130 
    Details
    ISSN: 1432-136X
    Keywords: Calorimetry ; Energy metabolism ; Honey bee castes ; Honey bees ; Apis mellifera carnica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Honey bees of different age and castes were investigated calorimetrically at 20, 25 and 30 °C. Experiments were completed by endoscopic observation of the insects in the visible and the near infrared range and by acoustical monitoring and subsequent frequency analysis of various locomotor activities. Direct calorimetric results of this paper are compared with data of indirect calorimetry from the literature using a respiratory quotient of 1.00 and 21.13 J consumed. Agreements between both methods are generally good. The results show that weight-specific heat production rates increase with age of worker bees by a factor of 5.6 at 30 °C, 3.7 at 25 °C and 40.0 at 20 °C. In groups of foragers the heat production decreases with growing group size to around 6% of the value for an isolated bee. The presence of a fertile queen or of brood reduces the heat output of a small worker group significantly. Adult drones exhibit a much higher metabolic rate (up to 19.7-fold at 20 °C) than juveniles with strong fluctuations in the power-time curves. Fertile queens show a less pronounced heat production rate than virgin queens (54% at 30 °C, 87% at 25 °C and 77% at 20 °C). Calorimetric unrest is much higher for young than for adult queens. Heat production is very low in both uncapped and capped brood and less than 30% of that of a newly emerged worker. In most cases temperature showed a significant influence on the metabolic level, although its sign was not homogeneous between the castes or even within them. Locomotor activities are easily recorded by the acoustic frequency spectrum (0–7.5 kHz) and in good agreement with endoscopic observations and calorimetric traces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398337
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal investigations of a honey bee colony: thermoregulation of the hive during summer and winter and heat production of members of different bee castes (1989)
    Springer
    Journal of comparative physiology 159 (1989), S. 551-560 
    Details
    ISSN: 1432-136X
    Keywords: Bees ; Calorimetry ; Heat production ; Temperature ; Thermoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The temperature at the centre, the periphery and the entrance of a honey bee colony (Apis mellifera carnica) was continuously determined during the summer season and the broodless time in winter. During the summer season the temperature in the brood nest averages 35.5°C with brief excursions up to 37.0°C and down to 33.8°C. Increasing environmental temperatures resulted in linear increases in the temperature of the hive entrance, its periphery and its centre. The temperature in the centre of an overwintering cluster is maintained at an average value of 21.3°C (min 12.0°C, max 33.5°C). With rising ambient temperatures the central temperature of a winter cluster drops whereas the peripheral temperature increases slightly. With decreasing external temperatures the peripheral temperature is lowered by a small amount while the cluster's centre temperature is raised. Linear relationships are observed between the central and the ambient temperature and between the central temperature and the temperature difference of the peripheral and the ambient temperatures. The slopes point to two minimum threshold values for the central (15°C) and the peripheral temperature (5°C) which should not be transgressed in an overwintering cluster. Microcalorimetric determinations of the heat production were performed on the three castes of the honey bee: workers, drones and queens of different ages. Among these groups single adult workers showed the highest heat production rates (209 mW·g−1) with only neglectible fluctuations in the heat production rate. Juvenile workers exhibited a mean heat production rate of 142 mW·g−1. The rate of heat production of adult workers is strongly dependent upon the number of bees together in a group. With more than 10 individuals weight-specific heat dissipation remains constant with increasing group sizes at a level approximately 1/17 that of an isolated bee. Differences are seen between the rates of virgin (117 mW·g−1) and laying (102 mW·g−1) queens. Laying queens showed less thermal fluctuations than virgin queens. High fluctuations in heat production rates are observed for drones. In both groups (fertile, juvenile) phases of high and extremely low activity succeed one another. The heat production of juvenile drones was 68 mW·g−1, that of fertile drones 184 mW·g−1 due to stronger locomotory activities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694379
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    Paper (German National Licenses)
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