scholarly journals Repeatability of standard metabolic rate and gas exchange characteristics in a highly variable cockroach, Perisphaeria sp.

2003 ◽  
Vol 206 (24) ◽  
pp. 4565-4574 ◽  
Author(s):  
E. Marais
2002 ◽  
Vol 205 (6) ◽  
pp. 791-798 ◽  
Author(s):  
Frances D. Duncan ◽  
Boris Krasnov ◽  
Megan McMaster

SUMMARY This study correlates the pattern of external gas exchange with the diel activity of nine species of tenebrionid beetle from the Negev Desert, Israel. The study species are active throughout the summer months when daytime temperatures are high and no rain falls. There were no differences in standard metabolic rate, determined by flow-through respirometry, among the nine species. All the nocturnally active beetles exhibited a form of continuous respiration, whereas the two diurnally active and one crepuscular species exhibited a cyclic form of respiration referred to as the discontinuous gas-exchange cycle (DGC). The DGCs recorded have a long flutter period consisting of miniature ventilations, and 29–48 % of the total CO2 output occurred during this period. In this study, the flutter period played an important role in the modulation of metabolic rate, in contrast to other studies in which the burst period has been shown to be important. We suggest that the long flutter period is important in reducing respiratory water loss in arid-dwelling arthropods. This study lends support to the hypothesis that discontinuous gas exchange is important in reducing respiratory water loss from beetles that need to minimise dessication because of the high water vapour pressure gradient they experience. If the use of underground burrows were responsible for the evolution of discontinuous gas exchange, then we would expect all nine tenebrionid species to use DGCs since both the nocturnally and diurnally active species bury in the sand during periods of inactivity. We conclude that the activity patterns of the beetles are more important than their habitat associations in designating the type of respiration used.


2016 ◽  
Vol 50 (1) ◽  
pp. 138-144
Author(s):  
Patrick J Ruhl ◽  
Robert N Chapman ◽  
John B. Dunning

2007 ◽  
Vol 164 (10) ◽  
pp. 1391-1393 ◽  
Author(s):  
Juan Jose Almaraz ◽  
Xiaomin Zhou ◽  
Alfred Souleimanov ◽  
Donald Smith

1975 ◽  
Vol 39 (1) ◽  
pp. 47-53 ◽  
Author(s):  
J. A. Loeppky ◽  
U. C. Luft

To clarify the role of O2 stores in the fluctuations in VO2 observed with changing posture, O2 intake (Veo2) and pulmonary capillary O2 transfer (Vpco2) were calculated breath by breath with a box-balloon sprometer and mass spectrometer. Changes in O2 stores of the lungs (O2L) and blood (O2b) were computed assuming metabolic rate (Vco2) constant (O2L = Veo2 - Vpco2; O2b = Vpco2 - Vco2). Measurements were made before, during, and after passive tilt to 60 degrees and on return to recumbency after 10 min erect. From supine to upright O2L increased rapidly and O2b dropped slowly, creating a net deficit in Veo2 of 130 ml in 10 min. Return to supine caused rapid loss in O2L and gain in O2b with a net Veo2 excess of 117 ml. Shifts in O2b were 2.5 times greater but opposite to shifts in O2L. Changes in O2b result from shifts in blood volume and flow more than from changes in cardiac output. Refilling of O2b, matching loss while upright, caused transient hypoxia with significant hyperpnea.


Biomolecules ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1693
Author(s):  
Javaria Afzal ◽  
Muhammad Hamzah Saleem ◽  
Fatima Batool ◽  
Ali Mohamed Elyamine ◽  
Muhammad Shoaib Rana ◽  
...  

The impact of heavy metal, i.e., cadmium (Cd), on the growth, photosynthetic pigments, gas exchange characteristics, oxidative stress biomarkers, and antioxidants machinery (enzymatic and non-enzymatic antioxidants), ions uptake, organic acids exudation, and ultra-structure of membranous bounded organelles of two rice (Oryza sativa L.) genotypes (Shan 63 and Lu 9803) were investigated with and without the exogenous application of ferrous sulfate (FeSO4). Two O. sativa genotypes were grown under different levels of CdCl2 [0 (no Cd), 50 and 100 µM] and then treated with exogenously supplemented ferrous sulfate (FeSO4) [0 (no Fe), 50 and 100 µM] for 21 days. The results revealed that Cd stress significantly (p < 0.05) affected plant growth and biomass, photosynthetic pigments, gas exchange characteristics, affected antioxidant machinery, sugar contents, and ions uptake/accumulation, and destroy the ultra-structure of many membranous bounded organelles. The findings also showed that Cd toxicity induces oxidative stress biomarkers, i.e., malondialdehyde (MDA) contents, hydrogen peroxide (H2O2) initiation, and electrolyte leakage (%), which was also manifested by increasing the enzymatic antioxidants, i.e., superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) and non-enzymatic antioxidant compounds (phenolics, flavonoids, ascorbic acid, and anthocyanin) and organic acids exudation pattern in both O. sativa genotypes. At the same time, the results also elucidated that the O. sativa genotypes Lu 9803 are more tolerant to Cd stress than Shan 63. Although, results also illustrated that the exogenous application of ferrous sulfate (FeSO4) also decreased Cd toxicity in both O. sativa genotypes by increasing antioxidant capacity and thus improved the plant growth and biomass, photosynthetic pigments, gas exchange characteristics, and decrease oxidative stress in the roots and shoots of O. sativa genotypes. Here, we conclude that the exogenous supplementation of FeSO4 under short-term exposure of Cd stress significantly improved plant growth and biomass, photosynthetic pigments, gas exchange characteristics, regulate antioxidant defense system, and essential nutrients uptake and maintained the ultra-structure of membranous bounded organelles in O. sativa genotypes.


2001 ◽  
Vol 23 (3) ◽  
pp. 522-525 ◽  
Author(s):  
ELIEMAR CAMPOSTRINI ◽  
OSVALDO KIYOSHI YAMANISHI ◽  
CARLOS A. MARTINEZ

In this research, was used four papaya (Carica papaya L.) genotypes: three from the 'Solo ( Sunrise Solo TJ, Sunrise Solo 72/12 and Baixinho de Santa Amália) group and one from the 'Formosa' group (Know-You 01). They were grown in plastic pots containing a sandy-clay-loam soil subjected to pH correction and fertilization, under greenhouse conditions. Throughout the experimental period plants were subjected to periodic irrigation to maintain the soil humitidy around field capacity. The experiment was conducted 73 days after sowing. In all genotypes, leaf gas exchange characteristics were determined. The net photosynthetic rate (A, mumol m-2 s-1 ), stomatal conductance (g s mol m-2 s-1), leaf temperature (T I, 0C) and intercellular carbon dioxide concentration (ci, muL L-1) on the 4th, 5th, 6th, 7th, 8th and 9th leaves from the plant apex were determined. No significant differences were observed for A, g s, c i, or Tl either among the leaves sampled from any of the genotypes. A was positively correlated with g s and in the other hand T I and g s were negatively correlated. The results suggest that, for 73 DAP, all the sampled papaya leaves functioned as sources of organs.


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