Carl L. Reiber Associate Professor Ph.D., University of Massachusetts, 1992 702-895-1549 reiber@ccmail.nevada.edu	Heart beat of the grass shrimp (Palaemonetes pugio)
	RESEARCH INTERESTS Publications CV

Comparative physiology - cardiovascular regulation/development: The intrinsic and extrinsic regulation of cardiovascular functions in Crustacea, with particular emphasis on neurohormonal control of cardiac physiology, ontogeny of regulatory mechanisms and adaptations of the cardio-respiratory systems to environmental stresses.

The traditional view of the invertebrate open circulatory system is one of low complexity and poor regulation. Over the past few years, research has shown the crustacean cardiovascular system capable of a high degree of regulation capable of responding to both internal and external demands. My research into the control and regulation of the cardiovascular system has focused on two areas: 1) the neurohormonal regulatory pathways established during embryonic and larval development, and 2) the plasticity of these systems in the face of changing physiological demands.

OVERVIEW

The crustacean heart consists of a single muscular chamber that is suspended within the pericardial sinus. During cardiac contraction, hemolymph is ejected through multiple arterial outlets, each artery supplying a defined region of the animal. An artery branches laterally three to four times before terminating in tissue sinuses where exchange takes place. Hemolymph then flows through a series of larger sinuses, passes through the gills and finally back to the heart. Control of hemolymph circulation may be imposed at any number of points along the circuit. The primary control mechanisms appear to be the force and rate of cardiac contraction and the tonus of the cardioarterial valves located at the entrance to each artery.

The heart and the cardioarterial valves respond to neurohormones such as proctolin, CCAP, serotonin and dopamine. Injection of neurohormones results in alteration of force and rate of cardiac contraction as well as modulation of arterial outflow via contraction of the valves. These regulatory pathways are established sequentially during embryonic development. The ontogenetic timing of this can determine if an embryo or larvae is able to meet the demands placed upon the developing organism both physiologically and environmentally. Changes to this developmental sequence in response to changing physiological demands or environmental conditions can potentially have long term effects on adult physiology. The ontogenetic timing of key regulatory pathways and physiological function of the cardiovascular system may allow crustaceans to exploit such diverse environments as anoxic burrows, warm estuary waters and terrestrial system.

As the crustacean cardiovascular system shows itself to be complex and highly regulation, many questions are being asked. Some of the more basic questions deal with fundamental hemodynamic issues during development (pressure-flow relationships), neurohormonal regulation by both the cardiac ganglion and pericardial organs, receptor-ligand interactions and intracellular transaction mechanisms. The technical advances seen in the field of physiology, coupled with advances in biochemistry, molecular biology and computer systems has led to an explosion in research in these areas.

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SELECTED PUBLICATIONS

Chapman, S.L. and Reiber, C.L. 1999. Influence of hypoxia on cardiac functions in the grass shrimp (Palaemonetes pugio Holthuis). Comp. Biochem. Physiol. A. (In Press)

McGaw, I.J. and Reiber, C.L. 1999. An integrated response to feeding in the blue crab (Callinectes sapidus). J. of Exp. Biol. (In Press).

McGaw, I.J., Reiber, C.L., and Guadagnoli, J.A. 1999. Behavioral physiology of four crab species to low salinity. Biological Bull. 196: 163-176.

McGaw, I.J. and Reiber, C.L. 1998. Circulatory modification in the blue crab (Callinectes sapidus), during exposure and acclimation to low salinity. Comp. Biochem. Physiol. A. 121: 67-76.

Reiber, C.L. and S. Malekpour and M. McDaniel. 1999. Effects of post hatching maintenance temperature on desert tortoise (Gopherus agassizii) shell morphology and thermoregulatory behavior. J. Herpetology. 33(2): 234-240.

Reiber, C.L. and B.R. McMahon. 1998. Progressive hypoxia's effects on the crustacean cardiovascular system: A comparison of the freshwater crayfish (Procambarus clarkii) and the lobster (Homarus americanus). J. Comp. Physiol. B. 168(3): 168-176..

Gleeson, R.A., Wheatly, M.G., McDowell, L.M., Reiber, C.L., and Aldrich, H.C. 1997. Morphological and physiological transformations in the olfactory sensilla of blue crabs acclimated to low salinity. J. Exp. Biol. 200: 445-456.

Reiber, C.L., B.R. McMahon, and W.W. Burggren. 1997. Cardiovascular functions in two Macruran decapod crustaceans (Procambarus clarkii and Homarus americanus) during periods of inactivity, tail flexion and cardiorespiratory pauses. J. Exp. Biol. 200: 1103-1113.

Reiber, C.L., and T. Wang. 1997. Control of arterial blood gases: Cardiovascular and ventilatory perspectives. Am. Zool. 36(1): 1-2.

Reiber, C.L. 1997. Ontogeny of cardiac and ventilatory function in the crayfish Procambarus clarkii. Am. Zool. 36(1): 82-91.

Birchard, G.F., and C.L. Reiber. 1996. Heart rate during development in the turtle embryo: Effect of temperature. J. Comp. Physiol. 166(8): 467-472.

Reiber, C.L., 1997. Oxygen sensitivity in the crayfish Procambarus clarkii: Peripheral O2 receptors and their effect on cardiorespiratory functions. J. Crustacean Biology 17(2): 197-206.

Birchard, G.F., and Reiber, C.L. 1995. Growth, metabolism and chorioallantoic vascular density of developing snapping turtles (Chelydra serpentina): Influence of temperature. Physiol. Zool. 68(5): 799-811.

Birchard, G.F., Walsh, T., Rosscoe, R., and Reiber, C.L. 1995. Oxygen uptake by the Komodo Dragon (Varanus komodoensis) eggs: The energetics of prolonged development in a reptile. Physiol. Zool. 68(4): 622-633

Reiber, C.L., 1995. Physiological adaptations of crayfish to the hypoxic environment. Am. Zool. 35(1): 1-11.

Reiber, C.L., 1994. The hemodynamics of Procambarus clarkii. Physiol. Zool. 67(2): 449-467.

Birchard, G.F., and Reiber, C.L. 1993. A comparison of Avian and Reptilian chorioallantoic vascular density. J. Exp. Biol. 178: 245-249.

Reiber, C.L. and Birchard, G.F., 1993. Effects of temperature on hemolymph pH and metabolism in the land crab Stoliczia abbotti. J. Thermobiol. 18(1): 49?52

Reiber, C.L., McMahon, B.R. and Burggren, W.W. 1992. Redistribution of cardiac output in response to hypoxia: a comparison of the freshwater crayfish Procambarus clarkii and the lobster Homarus americanus. Comp. Physiol. Basel. Karger. 1992, vol. 11, pp 2?28.

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