...Edward P. Snelling; Rebecca Duncker; Karl K. Jones; Erinn P. Fagan-Jeffries; Roger S. Seymour ABSTRACT Flying insects have the highest mass-specific metabolic rate of all animals. Oxygen is supplied to the flight muscles by a combination of diffusion and convection along the internal air-filled...

... to be overcome by either diffusion gas exchange within the burrow or some means of capturing wind energy to power steady or quasi-steady bulk flows of air through it. Both are examples of what may be called ‘DC’ models, namely steady to quasi-steady flows powered by steady to quasi-steady winds. Natural winds...

...Berlizé Groenewald; Stefan K. Hetz; Steven L. Chown; John S. Terblanche SUMMARY Gas exchange dynamics in insects is of fundamental importance to understanding evolved variation in breathing patterns, such as discontinuous gas exchange cycles (DGCs). Most insects do not rely solely on diffusion...

...George A. Jackson Summary The interactions between planktonic organisms and their aquatic environment are mediated by diffusive processes on the scale of millimeters and smaller. The uptake of nutrients and food and the release of metabolic products creates localized patchiness that diffusive...

...Stephen T. Kinsey; Bruce R. Locke; Richard M. Dillaman Summary Metabolic processes are often represented as a group of metabolites that interact through enzymatic reactions, thus forming a network of linked biochemical pathways. Implicit in this view is that diffusion of metabolites to and from...

...Gerolf Gros; Beatrice A. Wittenberg; Thomas Jue SUMMARY Myoglobin, a mobile carrier of oxygen, is without a doubt an important player central to the physiological function of heart and skeletal muscle. Recently, researchers have surmounted technical challenges to measure Mb diffusion in the living...

...Ana Gabriela Jimenez; Bruce R. Locke; Stephen T. Kinsey SUMMARY We examined the influence of intracellular diffusion of O 2 and high-energy phosphate (HEP) molecules on the scaling with body mass of the post-exercise whole-animal rate of O 2 consumption( V̇ O 2 ) and muscle arginine phosphate (AP...

...H. Arthur Woods; Amy L. Moran SUMMARY The Southern Ocean is one of the coldest, most stable marine environments on Earth and represents a unique environment for investigating metabolic consequences of low temperature. Here we test predictions of a new diffusion–reaction model of O 2 distributions...

.... J. Appl. Physiol. 94 , 353 -357. Kinsey, S. T. and Moerland, T. S. ( 2002 ). Metabolite diffusion in giant muscle fibers of the spiny lobster, Panulirus argus. J. Exp. Biol. 205 , 3377 -3386. Kinsey, S. T., Penke, B., Locke, B. R. and Moerland, T. S. ( 1999 ). Diffusional anisotropy...

..., as these animals grow, their muscle fibers greatly exceed the surface area to volume ratio and intracellular diffusion distance limits of most cells. Previous studies have shown that arginine phosphate (AP) recovery in the anaerobic (light) fibers, which demonstrate a fiber size dependence on anaerobic processes...

..., such that small crabs have fiber diameters that are typical of most cells (<60 μm) while in adult animals the fibers are giant (>600 μm). Thus, as the animals grow, their muscle fibers cross and greatly exceed the surface area to volume ratio( SA : V ) and intracellular diffusion distance threshold...

... along different paths by diffusion. The present study made use of the oxygen-sensitive phosphorescence probe Oxyphor R2 to analyze the internal oxygen pathway in the transparent microcrustacean Daphnia magna . Oxyphor R2 was injected into the circulatory system and the distribution of oxygen partial...

... in oxidative capacity that accompanies increases in animal mass, aerobic metabolic processes become increasingly limited by surface area to volume and intracellular diffusion constraints in developing white muscle fibers. We thank Dr Robert Roer and Dr Ann Pabst for their many valuable insights...

.... ( 2002 ). Circulatory oxygen transport in the water flea Daphnia magna. J. Comp. Physiol. B 172 , 275 -285. Bentley, T. B., Meng, H. and Pittman, R. N. ( 1993 ). Temperature dependence of oxygen diffusion and consumption in mammalian striated muscle. Am. J. Physiol. 264 , H1825 -H1830...

... argued that it is only in the `dead' state that diffusion reigns supreme in the body and the cell. If this is so, it follows that if we stop all convection inside the cell, it will be completely reliant on diffusional activity, and the question is raised of whether any level of metabolic activity...

... ). Diffusivity of myoglobin in intact. Proc. Natl. Acad. Sci. USA 91 , 3829 -3833. Kao, H. P., Abney, J. R. and Verkman A. S. ( 1993 ). Determinants of the translational mobility of a small solute in cell cytoplasm. J. Cell Biol. 120 , 175 -184. Kushmerick, M. J., Meyer, R. A. and Brown, T. R...

... analysis of pathways. This approach has served biology well and continues to be useful. Here, we consider the diffusion of small and large molecules in muscles and energy metabolism in the context of intracellular space. We find that in attempting to explain certain phenomena, a purely kinetic paradigm...

...-induced membrane recruitment of the cytoplasmic protein SOS results in the activation of the Ras/MAPK cascade. It has been suggested that the membrane recruitment of signaling proteins causes an increase in the diffusion-limited rates. We have recently shown that this increase is too small...

...Stephen T. Kinsey; Timothy S. Moerland SUMMARY The time- and orientation-dependence of metabolite diffusion in giant muscle fibers of the lobster Panulirus argus was examined using 31 P- and 1 H-pulsed-field gradient nuclear magnetic resonance. The 31 P resonance for arginine phosphate and the 1 H...

... derived from stereological analysis of electron micrographs, mean fibre P O 2 was calculated on the basis of temperature-corrected rates of mitochondrial respiration and oxygen diffusion. The mean muscle fibre diameter (MFD) among Antarctic notothenioids was in the range 17–61 μm and mitochondrial volume...