Undiluted cytosolic extracts were prepared from fast glycolytic muscle tissue of white perch (Morone americanus). Diffusion coefficients (D) through the cytosol preparations were estimated in vitro for a series of selected low molecular weight compounds using an experimental diffusion chamber. Determinations were made at 5 degrees and 25 degrees C to assess thermal sensitivity of the process. Non-metabolizable analogues of naturally occurring compounds were employed to avoid chemical alteration of solutes by the catalytically competent preparations during diffusion experiments. Kinematic viscosity of cytosolic extracts, which is a major determinant of diffusive resistance, increases from 2.94 +/− 0.06 to 5.35 +/− 0.02 X 10(−2) cm2 s-1 between temperatures of 25 degrees and 5 degrees C (Q10 = 1.35 +/− 0.01). The diffusion coefficients (D) of D-lactic acid are 2.26 +/− 0.84 and 0.79 +/− 0.15 X 10(−6) cm2s-1 at 25 degrees and 5 degrees C, respectively (Q10 = 1.84 +/− 0.36). The D values of 2-deoxyglucose are 2.87 +/− 1.01 and 1.22 +/− 0.36 X 10(−6) cm2s-1 at 25 degrees and 5 degrees C (Q10 = 1.75 +/− 0.54). The D values of Ca2+ are 2.47 +/− 0.28 and 1.09 +/− 0.36 X 10(−6) cm2s-1 at 25 degrees and 5 degrees C (Q10 = 2.04 +/− 0.36). The D values for the ATP analogue, AMP-PNP, are 0.87 +/− 0.33 and 0.81 +/− 0.15 X 10(−6) cm2s-1 at 25 degrees and 5 degrees C (Q10 = 0.98 +/− 0.12). AMP-PNP is the only compound tested which did not show significant thermal sensitivity of diffusion. Recently reported changes in muscle cell ultrastructure induced by temperature acclimation of fishes may serve to counteract the effect of temperature change on diffusion of key small molecules through the aqueous cytoplasm, thus maintaining flux rates between cellular compartments. These mechanisms may be of considerable import in achieving relative temperature independence of cellular function that is characteristic of many eurythermal aquatic animals.
In the field: an interview with Sönke Johnsen
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Sönke Johnsen is a Professor at Duke University, USA, investigating visual ecology and he talks about his experiences of collecting transparent animals while blue water diving and in a submersible, as well as outrunning Hurricane Katrina.
Call for new preLighters
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preLights is the preprint highlighting community supported by The Company of Biologists. At the heart of preLights are our preLighters: early-career researchers who select and write about interesting new preprints for the research community. We are currently looking for new preLighters to join our team. Find out more and apply here.
Graham Scott in conversation with Big Biology
Graham Scott talks to Big Biology about the oxygen cascade in mice living on mountaintops, extreme environments for such small organisms. In this JEB-sponsored episode, they discuss the concept of symmorphosis and the evolution of the oxygen cascade.
Trap-jaw ants coordinate tendon and exoskeleton for perfect mandible arc
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Trap-jaw ants run the risk of tearing themselves apart when they fire off their mandibles, but Greg Sutton & co have discovered that the ants simultaneously push and pull the mandibles using energy stored in a head tendon and their exoskeleton to drive the jaws in a perfect arc.
Hearing without a tympanic ear
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In their Review, Grace Capshaw, Jakob Christensen-Dalsgaard and Catherine Carr explore the mechanisms of hearing in extant atympanate vertebrates and the implications for the early evolution of tympanate hearing.
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