Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

Spadefoot toads are dormant underground for 9-10 months each year and emerge only with summer rains to briefly breed and feed. To determine whether dormancy necessitated changes in organ intermediary metabolism or signal transduction capacity, we quantified activities of 32 enzymes in brain, liver and skeletal muscle of control vs 2-month estivated toads. Estivation-induced changes in brain were consistent with suppressed glycolysis and increased ketone body and amino acid catabolism. In liver, estivation reduced activities of 8 enzymes from carbohydrate, amino acid, ketone body and phosphagen metabolism. Large scale reorganization of skeletal muscle occurred during estivation with generally elevated activities of enzymes of carbohydrate catabolism and reduced activities of fatty acid synthesis and ketone body enzymes. Increased glutamate dehydrogenase in brain and muscle along with altered tissue free amino acids pools probably supports urea accumulation as a defense against dehydration during dormancy. Seven organs showed reduced percentages of protein kinase A present as the active catalytic subunit during estivation and three had lower percentages of membrane-bound, active protein kinase C. Protein phosphatase activities were also generally reduced. The results indicate that anuran estivation includes metabolic reorganization via changes in maximal activities of key enzymes of intermediary metabolism and metabolic rate depression mediated by suppression of signal transducing enzymes.

Back to the top.
Poster Number PAstorey0151
Keywords: amphibian, dormancy, protein kinases, glycolysis, energy metabolism