Enzyme activity in the aestivating Green-striped burrowing frog (Cyclorana alboguttata) |
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Authors: | Beth L Mantle Helga Guderley Nicholas J Hudson Craig E Franklin |
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Institution: | (1) School of Biological Sciences, The University of Queensland, St Lucia, 4072, Australia;(2) Departement de biologie, Universite Laval, Quebec, G1V 0A6, Canada;(3) Livestock Industries, CSIRO, St Lucia, 4072, Australia; |
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Abstract: | Green-striped burrowing frogs (Cyclorana alboguttata) can depress their resting metabolism by more than 80% during aestivation. Previous studies have shown that this species
is able to withstand long periods of immobilisation during aestivation while apparently maintaining whole muscle mass and
contractile performance. The aim of this study was to determine the effect of prolonged aestivation on the levels of metabolic
enzymes (CCO, LDH and CS) in functionally distinct skeletal muscles (cruralis, gastrocnemius, sartorius, iliofibularis and
rectus abdominus) and liver of C. alboguttata. CS activity was significantly reduced in all tissues except for the cruralis, gastrocnemius and the liver. LDH activity
was significantly reduced in the sartorius and rectus abdominus, but remained at control (active) levels in the other tissues.
CCO activity was significantly reduced in the gastrocnemius and rectus abdominus, and unchanged in the remaining tissues.
Muscle protein was significantly reduced in the sartorius and iliofibularis during aestivation, and unchanged in the remaining
muscles. The results suggest that the energy pathways involved in the production and consumption of ATP are remodelled during
prolonged aestivation but selective. Remodelling and subsequent down-regulation of metabolic activity seem to target the smaller
non-jumping muscles, while the jumping muscles retain enzyme activities at control levels during aestivation. These results
suggest a mechanism by which aestivating C. alboguttata are able to maintain metabolic depression while ensuring that the functional capacity of critical muscles is not compromised
upon emergence from aestivation. |
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