scholarly journals Discontinuous gas-exchange cycle characteristics are differentially affected by hydration state and energy metabolism in gregarious and solitary desert locusts

2015 ◽  
Vol 218 (23) ◽  
pp. 3807-3815 ◽  
Author(s):  
S. Talal ◽  
A. Ayali ◽  
E. Gefen
Keyword(s):  
Energy Metabolism ◽  
Gas Exchange ◽  
Hydration State ◽  
Discontinuous Gas Exchange Cycle

Energy Metabolism: Errors in Gas-Exchange Conversion Factors

1988 ◽  
Vol 61 (6) ◽  
pp. 507-513 ◽  
Author(s):  
James A. Gessaman ◽  
Kenneth A. Nagy
Keyword(s):  
Energy Metabolism ◽  
Gas Exchange ◽  
Conversion Factors

scholarly journals Animal welfare of barrows with different antemortem lairage times without food

2013 ◽  
Vol 58 (No. 6) ◽  
pp. 305-311 ◽  
Author(s):  
P. Roldan-Santiago ◽  
D. Mota-Rojas ◽  
I. Guerreo-Legarreta ◽  
P. Mora-medina ◽  
F. Borderas-Tordesillas ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Energy Metabolism ◽  
Gas Exchange ◽  
Animal Welfare ◽  
Severe Dehydration ◽  
Acid Base ◽  
Treatment Groups ◽  
Baseline Levels

This study evaluated the effect of five different periods of antemortem lairage without food on the energy metabolism, gas exchange, mineral and blood acid-base balances of 1174 hybrid barrows, which were divided into six treatment groups according to the lairage period: 130 barrows were considered for the evaluation of the baseline levels (G<sub>B</sub>); 214 had 0 h of lairage (R<sub>0</sub>); 228 had 4 h of lairage (R<sub>4</sub>); 204 had 8 h of lairage (R<sub>8</sub>); 192&nbsp;had 12&nbsp;h of lairage (R<sub>12</sub>); and 206 had 24 h (R<sub>24</sub>). In all groups, increasing lairage periods triggered a significant reduction (P &lt; 0.05) in pH, accumulation of lactic acid and percentage of hematocrit. These findings led to the conclusion that antemortem lairage periods longer than 4 h cause hyperglycaemia, hypercalcaemia, hyperlactataemia, hyperkalaemia, hyponatraemia, acidosis, and more severe dehydration in barrows. &nbsp;

Ant breathing: testing regulation and mechanism hypotheses with hypoxia

1995 ◽  
Vol 198 (7) ◽  
pp. 1613-1620 ◽  
Author(s):  
J Lighton ◽  
D Garrigan
Keyword(s):  
Gas Exchange ◽  
Water Loss ◽  
Negative Pressure ◽  
Co2 Emission ◽  
Nitrogen Accumulation ◽  
Phase Duration ◽  
O2 Concentration ◽  
Flow Through ◽  
Discontinuous Gas Exchange Cycle ◽  
And Function

Using normoxic and hypoxic flow-through respirometry, we investigated the regulation of the closed-spiracle (C) and the nature of the fluttering-spiracle (F) phases of the discontinuous gas-exchange cycle (DGC) of the ant Camponotus vicinus. We predicted that as ambient O2 concentrations declined, DGC frequency would increase, because C phase duration would decrease (reflecting earlier hypoxic initiation of the F phase) and F phase duration would shorten (reflecting nitrogen accumulation), if convective mass inflow caused by a negative pressure gradient across the spiracles, rather than by diffusion, is the dominant F phase gas-exchange mechanism. C phase duration decreased with declining ambient O2 concentrations, as predicted. In contrast, DGC frequency decreased and F phase duration increased with decreasing ambient O2 concentrations. This was opposite to the expected trend if gas exchange in the F phase was mediated by convection, as is generally hypothesized. We therefore cannot disprove that F phase gas exchange was largely or purely diffusion-based. In addition, our data show equivalent molar rates of H2O and CO2 emission during the F phase. In contrast, during the open-spiracle phase, the duration of which was not affected by ambient O2 concentration, far more H2O than CO2 was lost. We discuss these findings and suggest that current hypotheses of F phase gas-exchange mechanisms and function in reducing respiratory water loss in adult insects may require revision.

Hypotheses regarding the discontinuous gas exchange cycle (DGC) of insects

2014 ◽  
Vol 4 ◽  
pp. 48-53 ◽  
Author(s):  
Heidy L Contreras ◽  
Erica C Heinrich ◽  
Timothy J Bradley
Keyword(s):  
Gas Exchange ◽  
Discontinuous Gas Exchange Cycle

scholarly journals Anaplerotic flux into the Calvin-Benson cycle. Integration in carbon and energy metabolism of Helianthus annuus

2021 ◽  
Author(s):  
Thomas Wieloch ◽  
Angela Augusti ◽  
Juergen Schleucher
Keyword(s):  
Energy Metabolism ◽  
Gas Exchange ◽  
Helianthus Annuus ◽  
Change Point ◽  
Carbon Flux ◽  
Growth Conditions ◽  
Central Component ◽  
Limited Growth ◽  
Isotope Evidence ◽  
Anaplerotic Pathway

Plants assimilate carbon primarily via the Calvin-Benson cycle. Two companion papers reports evidence for anaplerotic carbon flux into this cycle. To estimate flux rates in Helianthus annuus leaves based on gas exchange measurements, we here expanded Farquhar-von Caemmerer-Berry photosynthesis models by terms accounting for anaplerotic respiration and energy recycling. In line with reported isotope evidence (companion papers), we found relative increases in anaplerotic flux as intercellular CO2 concentrations, Ci, decrease below a change point. At Ci=136 and 202 ppm, we found absolute rates of 2.99 and 2.39 μmol Ru5P m-2 s-1 corresponding to 58.3 and 28.2% of net CO2 assimilation, 13.1 and 10.7% of ribulose 1,5-bisphosphate regeneration, and 22.2 and 15.8% of Rubisco carboxylation (futile carbon cycling), respectively. Anaplerotic respiration governs total day respiration with contributions of 81.3 and 77.6%, and anaplerotic relative to photorespiratory CO2 release amounts to 63.9 and 67%, respectively. Furthermore, anaplerotic flux significantly increases absolute ATP demands and ATP-to-NADPH demand ratios of photosynthesis and may explain increasing sucrose-to-starch carbon partitioning ratios with decreasing Ci. We propose that anaplerotic flux can occur under both Rubisco and RuBP-limited growth conditions. Overall, our work introduces the anaplerotic pathway as central component in carbon and energy metabolism of C3 plants.

scholarly journals Evaporative Cooling in the Desert Cicada: Thermal Efficiency and Water*sol;Metabolic Costs

1991 ◽  
Vol 159 (1) ◽  
pp. 269-283
Author(s):  
NEIL F. HADLEY ◽  
MICHAEL C. QUINLAN ◽  
MICHAEL L. KENNEDY
Keyword(s):  
Body Temperature ◽  
Gas Exchange ◽  
Water Loss ◽  
Thermal Efficiency ◽  
Evaporative Cooling ◽  
Water Flux ◽  
Simultaneous Measurements ◽  
Metabolic Costs ◽  
Hydration State

Using plant xylem water for evaporative cooling, the desert cicada Diceroprocta apache can maintain a body temperature as much as 5°C below ambient (Ta=42°C). Simultaneous measurements of water loss and gas exchange for cicadas feeding on perfused twigs show substantial increases in transpiration at temperatures at which evaporative cooling begins (between 37 and 38°C), but only modest increases in Vo2 and Vco2. The extent and duration of evaporative cooling depend on the cicada's hydration state and the rate of water flux from cuticular pores located on the surface of the thorax and abdomen.

scholarly journals A test of the oxidative damage hypothesis for discontinuous gas exchange in the locust Locusta migratoria

2012 ◽  
Vol 8 (4) ◽  
pp. 682-684 ◽  
Author(s):  
Philip G. D. Matthews ◽  
Edward P. Snelling ◽  
Roger S. Seymour ◽  
Craig R. White
Keyword(s):  
Gas Exchange ◽  
Oxidative Damage ◽  
Breathing Pattern ◽  
Critical Level ◽  
Locusta Migratoria ◽  
Respiratory Control ◽  
Breath Holding ◽  
Adaptive Value ◽  
Partial Pressures ◽  
Discontinuous Gas Exchange Cycle

The discontinuous gas exchange cycle (DGC) is a breathing pattern displayed by many insects, characterized by periodic breath-holding and intermittently low tracheal O 2 levels. It has been hypothesized that the adaptive value of DGCs is to reduce oxidative damage, with low tracheal O 2 partial pressures ( P O 2 ∼2–5 kPa) occurring to reduce the production of oxygen free radicals. If this is so, insects displaying DGCs should continue to actively defend a low tracheal P O 2 even when breathing higher than atmospheric levels of oxygen (hyperoxia). This behaviour has been observed in moth pupae exposed to ambient P O 2 up to 50 kPa. To test this observation in adult insects, we implanted fibre-optic oxygen optodes within the tracheal systems of adult migratory locusts Locusta migratoria exposed to normoxia, hypoxia and hyperoxia. In normoxic and hypoxic atmospheres, the minimum tracheal P O 2 that occurred during DGCs varied between 3.4 and 1.2 kPa. In hyperoxia up to 40.5 kPa, the minimum tracheal P O 2 achieved during a DGC exceeded 30 kPa, increasing with ambient levels. These results are consistent with a respiratory control mechanism that functions to satisfy O 2 requirements by maintaining P O 2 above a critical level, not defend against high levels of O 2 .

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