Warm-up and substrate cycling in flight muscles of male bumblebees, Bombus terrestris

Surholt, Bernhard; Greive, Heinrich; Baal, Thomas; Bertsch, Andreas

doi:10.1016/0300-9629(91)90536-l

Cited by 6 publications

(5 citation statements)

References 30 publications

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“…In this experiment, wasps were moved from a cool environment to a warmer environment; thus, some of the rapid warming observed may have been due to the inspiration of warmer ambient air, although this cannot explain those wasps that had body region temperatures above ambient. Our results raise the question of whether some or all of this temperature increase could be due to a futile cycle as has been observed in bumblebees (Surholt et al, 1991;Staples et al, 2004). While the futile cycle does not appear to be a large part of warming in bumblebees (Staples et al, 2004), the weak temperature elevation observed at low temperatures in Polistes could potentially be caused by a futile cycle.…”

Section: Discussionmentioning

confidence: 42%

Thermoregulation in the primitively eusocial paper wasp, Polistes dominulus

et al. 2009

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Regulation of wing muscle temperature is important for sustaining flight in many insects, and has been well studied in honeybees. It has been much less well studied in wasps and has never been demonstrated in Polistes paper wasps. We measured thorax, head, and abdomen temperatures of inactive Polistes dominulus workers as they warmed after transfer from 8 to *25°C ambient temperature, after removal from hibernacula, and after periods of flight in a variable temperature room. Thorax temperature (T th ) of non-flying live wasps increased more rapidly than that of dead wasps, and T th of some live wasps reached more than 2°C above ambient temperature (T a ), indicating endothermy. Wasps removed from hibernacula had body region temperatures significantly above ambient. The T th of flying wasps was 2.5°C above ambient at T a = 21°C, and at or even below ambient at T a = 40°C. At 40°C head and abdomen temperatures were both more than 2°C below T a , indicating evaporative cooling. We conclude that P. dominulus individuals demonstrate clear, albeit limited, thermoregulatory capacity.

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Section: Discussionmentioning

confidence: 42%

Thermoregulation in the primitively eusocial paper wasp, Polistes dominulus

et al. 2009

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“…This rate of cycling would produce less than 2% of the heat required to keep a bumblebee thorax warm on a cold day. It is worth noting that another study on B. terrestris males has estimated that during the pre-flight 'warm-up' phase cycling occurred at a rate of 249·µmol·g -1 ·muscle·min -1 , and this could contribute significantly to thermogenesis (Surholt et al, 1991). We suspect, however, that this result is an artefact of the isotopic method employed, as the reported cycling rate is ~4-fold greater than PFK and FbPase activities found in B. terrestris workers (Newsholme et al, 1972).…”

Section: Activitiesmentioning

confidence: 81%

“…During tethered flight, B. terrestris workers consume oxygen at a rate of 27.5·ml·g -1 ·body·mass·h -1 (Wolf et al, 1996). Assuming that virtually all of this oxygen is consumed by flight muscles and that flight muscle comprises 32.4% of body mass (Surholt et al, 1991), this corresponds to a glycolytic flux of 10.5·µmol·hexose·g -1 ·muscle·min -1 . This value is within the range of 7.6-19.1·µmol·hexose·g -1 ·muscle·min -1 estimated for free-flying male (Surholt et al, 1991) and queen (Silvola, 1984) B. terrestris, respectively.…”

Section: Activitiesmentioning

confidence: 99%

“…Assuming that virtually all of this oxygen is consumed by flight muscles and that flight muscle comprises 32.4% of body mass (Surholt et al, 1991), this corresponds to a glycolytic flux of 10.5·µmol·hexose·g -1 ·muscle·min -1 . This value is within the range of 7.6-19.1·µmol·hexose·g -1 ·muscle·min -1 estimated for free-flying male (Surholt et al, 1991) and queen (Silvola, 1984) B. terrestris, respectively. This glycolytic flux represents only 10.6% of the maximal PFK catalytic capacity measured in the present study, a low fractional velocity (pathway flux/maximal enzymatic capacity) compared with honeybees (Suarez et al, 1997) and the 26.1% observed in B. impatiens workers (J. F. Staples and R. P. Maloney, unpublished data).…”

Section: Activitiesmentioning

confidence: 99%

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`Futile cycle' enzymes in the flight muscles of North American bumblebees

Staples

Koen

Laverty

2004

Journal of Experimental Biology

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In the flight muscles of European bumblebees, high activities of fructose-1,6-bisphosphatase (FbPase) relative to phosphofructokinase (PFK) have suggested a thermogenic 'futile cycle' important for regional endothermy. We find generally low activities of FbPase (0.7-19.7·units·g -1 ·thorax) in North American Bombus species, with the exception of Bombus rufocinctus, where activity (43.1·units·g -1 ·thorax) is comparable with that of European congeners. These data, taken with estimates of maximal rates of heat production by cycling, do not support a significant thermogenic role for the PFK/FbPase cycle. In agreement with earlier studies, both PFK and FbPase activities were found to scale allometrically with body size (allometric exponents -0.18 and -1.33, respectively). The cycle may serve to supplement thermogenesis or amplify glycolytic flux in rest-to-flight transitions, especially in smaller bees.

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“…Futile substrate cycles are a long-standing concept and various examples have been showcased in an array of different invertebrate and vertebrate species. Several glycolytic substrate cycles in insects [ [6] , [7] , [8] ], a futile calcium (Ca 2+ ) cycle in the heater organ of a large pelagic predatory fish, the blue marlin [ 9 ], an extracellular inter-organ lipid cycle between liver and adipose tissue as well as an intracellular adipocyte-specific triglyceride/fatty acid (TG/FA) cycle in rodents and humans [ [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] ], futile substrate cycling between de novo FA synthesis and FA oxidation in skeletal muscle of mice [ 21 ], and futile Ca 2+ cycling mediated by sarcoplasmic reticulum calcium ATPase (SERCA) pump activity in skeletal muscle of mammals, reviewed in [ 22 ]. For thermogenic adipocytes, there has been a recent revival of interest in futile substrate cycles [ 23 ], since ATP driven cyclic Ca 2+ pumping [ 24 ] and cyclic interconversion of creatine/creatine-phosphate [ 25 ] were discovered as contributors to NST in murine adipose tissues and the control of whole-body energy homeostasis.…”

Section: Introductionmentioning

confidence: 99%