RESEARCH THEME - 2 Novel in vitro and in vivo protocols
Part of my past and ongoing work has been to develop protocols to monitor cellular responses (pH, O2 transport, ion-regulation, water balance) to environmental stress in fish.
Caldwell, S., Rummer, J.L., Brauner, C.J. 2006. Blood sampling techniques and storage duration: Effects on the presence and magnitude of the red blood cell β-adrenergic response in rainbow trout, Oncorhynchus mykiss. Comparative Biochemistry and Physiology A 144(2): 188-195. doi:10.1016/j.cbpa.2006.02.029
Clark, T.D., Rummer, J.L., Sepulveda, C.A., Farrell, A.P., Brauner, C.J. 2009. Reduced and reversed temperature dependence of blood oxygenation in an ectothermic scombrid fish: implications for the evolution of regional heterothermy? Journal of Comparative Physiology B: Biochemical, Systems, and Environmental Physiology 180(1):73-82. doi:10.1007/s00360-009-0388-7
Rummer, J.L., Roshan-Moniri, M., Balfry, S.K., Brauner, C.J. 2010. Use it or lose it? Sablefish, Anoplopoma fimbria, a species representing a fifth teleostean group where the βNHE associated with the red blood cell adrenergic stress response has been secondarily lost. Journal of Experimental Biology 213, 1503-1512. doi:10.1242/jeb.038844
Under this theme, one of my most important contributions to my research field has concerned the evolution of O2 transport in fish, specifically the capacity of mild acidosis, such as environmental hypercapnia (high CO2) or exercise, to aid in enhancing O2 delivery.
Rummer, J.L., McKenzie, D.J., Innocenti, A., Supuran, C.T., Brauner, C.J. 2013. Root effect haemoglobin may have evolved to enhance general oxygen delivery. Science 340, 1327-1329. doi:10.1126/science.1233692
Rummer, J.L., Brauner, C.J. 2011. Plasma-accessible carbonic anhydrase at the tissue of a teleost fish may greatly enhance oxygen delivery: in vitro evidence in rainbow trout, Oncorhynchus mykiss. Journal of Experimental Biology 214, 2319-2328. doi:10.1242/jeb.054049
Brauner, C.J. and Rummer, J.L. 2011. Gas Transport and Exchange: Interaction Between O2 and CO2 Exchange. In: Farrell A.P., (ed.), Encyclopedia of Fish Physiology: From Genome to Environment, volume 2, pp. 916-920. San Diego: Academic Press. doi:10.1016/B978-0-1237- 4553-8.00115-5
This discovery sheds insight into the evolution of one of the most successful groups of vertebrates: the fishes.
Randall, D.J., Rummer, J.L., Wilson, J.M. Wang, S., Brauner, C.J. 2014. Review: A unique mode of tissue oxygenation and the success of teleost fish. Journal of Experimental Biology 217, 1205-1214. doi:10.1242/jeb.093526
Building on this discovery, I have also determined that some teleosts and elasmobranchs appear to maintain or even enhance metabolic performance upon acclimation to elevated CO2 levels that will accompany ocean acidification in the coming decades.
Munday, P.L., Cheal, A., Dixson, D.L., Rummer, J.L. Fabricius, K. 2014. Behavioural impairment in reef fishes caused by ocean acidification at CO2 seeps. Nature Climate Change 4, 487-492. doi:10.1038/NCLIMATE2195
Rummer, J.L., Stecyk, J.A.W., Couturier, C.S., Watson, S-A., Nilsson, G.E., Munday, P.L. 2013. Elevated CO2 enhances aerobic scope of a coral reef fish. Conservation Physiology 1, doi:10.1093/conphys/cot023
Couturier, C.S., Stecyk, J.A.W., Rummer, J.L., Munday, P.L., Nilsson, G.E. 2013. Species specific effects of near-future CO2 on the respiratory performance of two tropical prey fish and their predator. Comparative Physiology and Biochemistry - A 166:482-489. doi:10.1016/j.cbpa.2013.07.025
Heinrich, D.D.U., Rummer, J.L., Morash, A.J., Watson, S-A., Simpfendorfer, C.A, Heupel, M.R., Munday, P.L. A product of its environment: The epaulette shark (Hemiscyllium ocellatum) exhibits physiological tolerance to elevated environmental CO2. Conservation Physiology (accepted 3 Aug. 2014)
I have since delved into the mechanistic basis for enhanced performance, from the level of the mitochondria, ion transporters, and metabolic enzymes in the gill and muscle, to the O2 transport capacity of the blood. My foundation in mechanistic physiology and techniques I have honed over the past several years, including microsurgery, implanting fiber optic O2 sensors directly into muscle tissue or arteries to monitor O2 delivery in real- time, imaging blood flow patterns during environmental or exercise-induced stress, and assessing the effects of various environmental factors on O2 binding properties of blood have helped me to design integrative studies to link physiological mechanisms to how an organism copes in its environment.
Rummer, J.L., Wang, S., Steffensen, J.F., Randall, D.J. 2014. Function and control of the fish secondary vascular system, a contrast to mammalian lymphatic systems. Journal of Experimental Biology 217(5):751-757. doi:10.1242/jeb.086348