Research Summary

The major goal of my research is to understand the physiological mechanisms that adapt animals to stresses such as anoxia, acidosis, and variable temperature. The focus is on ectothermic vertebrates, such as freshwater turtles, that can survive long periods without oxygen and can function over a wide range of body temperatures.  Studies are carried out on whole animals, on isolated organs, and on cell preparations.

Current research seeks to understand the mechanisms that permit a freshwater turtle to survive prolonged submergence, particularly during its winter hibernation when ice cover prevents breathing.  Experiments consider the ecological situations in which the animals are either in anoxic or oxygenated water.  Specific objectives are to understand the role of the shell and skeleton in acid buffering, to clarify the fate of lactate during recovery from anoxia, to explore the response of heart and heart muscle to graded hypoxia, and to define the mechanisms and limitations of aquatic gas exchange.

My laboratory has also continued an interest in the comparative physiology of respiration and gas exchange.  Recent work in this area includes investigations of the metabolic cost of breathing in turtles, gas exchange and acid-base balance during torpor in the little brown bat, Eptesicus fuscus, and the functional significance of aerial gas exchange in air-breathing fishes.

Recent Publications

Shi, H., P.H. Hamm, R.S. Meyers, R.G. Lawler, and D.C. Jackson (1997). Intracellular pH regulation of isolated turtle heart during normoxic and anoxic acidosis: a 31P-NMR study. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 272: R6-R15.

Shi, H. and D.C. Jackson (1997). Effects of anoxia, acidosis and temperature on the contractile properties of turtle cardiac muscle strips. J. Exp. Biol. 200: 1965â1973.

Jackson, D.C. (1997). Lactate accumulation in the shell of the turtle, Chrysemys picta bellii, during anoxia at 3 and 10oC. J. Exp. Biol. 200: 2295-2300.

Farmer, C.G. and D. C. Jackson (1998). Air-breathing during activity in the fishes Amia calva and Lepisosteus oculatus. J. Exp. Biol. 201: 943-948.

Jackson, D.C. (1999). The role of the turtle shell in acid-base buffering. In: Regulation of Tissue pH in Animals  and Plants, E.W. Taylor, S. Egginton, and J.A. Raven, eds., Cambridge Univ. Press, Cambridge, pp. 215-231.

Shi, H., P.H. Hamm, R.G. Lawler, and D.C. Jackson (1999). Different effects of simple anoxic lactic acidosis and simulated in vivo anoxic acidosis on turtle heart. Comp. Biochem. Physiol. A, 122: 173-180.

Crocker, C.E., G.R. Ultsch, and D.C. Jackson (1999). The physiology of diving in a north temperate and three tropical turtle species. J. Comp. Physiol. B 169: 249-255.

Jackson, D.C., Z. Goldberger, S. Visuri, and R.N. Armstrong (1999). Ionic exchanges of turtle shell in vitro and their relevance to shell function in the anoxic turtle. J. Exp. Biol. 202: 513-520.

Ultsch, G.R., M.E. Carwile, C.E. Crocker, and D.C. Jackson (1999). The physiology of hibernation among painted turtles: the eastern painted turtle, Chrysemys picta picta. Physiol. Biochem. Zool. 72: 493-501.

Crocker, C.E., T.E. Graham, G.R. Ultsch, and D.C. Jackson (2000). Physiology of common map turtles (Graptemys geographica) hibernating in the Lamoille River, Vermont. J. Exp. Zool. 286: 143-148.

Jackson, D.C. (2000). How a turtle’s shell helps it survive prolonged anoxic acidosis. News in Physiological Sciences 15: 181-185.

Jackson, D.C., A.L. Ramsey, J.M. Paulson, C.E. Crocker, and G.R. Ultsch (2000). Lactic acid buffering by bone and shell in anoxic softshell and painted turtles. Physiol. Biochem. Zool. 73:290-297.

Jackson, D.C., C.E. Crocker, and G.R. Ultsch (2000). Bone and shell contribution to lactic acid buffering of submerged turtles Chrysemys picta bellii at 3oC. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 278: R1564-R1571.

Crocker, C.E., R. Feldman, G.R. Ultsch, and D.C. Jackson (2000). Overwintering behavior and physiology of eastern painted turtles (Chrysemys picta picta) in Rhode Island. Can. J. Zool. 78: 936-942.

Jackson, D.C. (2000). Living without oxygen: lessons from the freshwater turtle. Comp. Biochem. Physiol. A. 125: 299-315.

Reese, S.A., C.E. Crocker, D.C. Jackson, and G.R. Ultsch (2000). The physiology of hibernation among painted turtles: the midland painted turtle (Chrysemys picta marginata). Respir. Physiol. 24: 43-50.

Jackson, D.C., T. Wang, P. Koldkjaer, and E.W. Taylor (2001). Lactate sequestration in the carapace of the crayfish Austropotamobius pallipes during exposure in air. J. Exp. Biol. 204: 941-946.

Jackson, D.C. (2001). Anoxic survival and metabolic arrest in the turtle. Chap. 6 in: Life in Limbo: Molecular Mechanisms of Metabolic Arrest, K. Storey, ed., BIOS Scientific Publishers Ltd., Oxford. Pp. 103-114.

Reese, S.A., C.E. Crocker, M.E. Carwile, D.C. Jackson, and G.R. Ultsch. (2001).  The physiology of hibernation in common map turtles (Graptemys geographica).  Comparative Biochemistry and Physiology A. 130:331-340.