David W. Kraus

Research Description:

Organisms that have evolved under harsh conditions often display dramatic variations of physiological themes. My research is concerned with adaptations that have ensured the success of animals that flourish in extreme environments. Two important constituents of marine benthic habitats that have influenced invertebrate evolution are oxygen, which is often limited, and sulfide, which is toxic to cellular oxygen consuming pathways. An extreme adaptation of sulfide environments is the incorporation of chemoautotrophic sulfide-oxidizing bacteria into specialized cells, observed in annelid and pogohophoran worms and bivalve mollusks. These symbiotic bacteria oxidize sulfide and fix carbon dioxide into nutrients that are translocated to the host. To fuel the symbiosis, the host in turn must deliver both oxygen and sulfide to intracellular symbionts and its own mitochondria. Recently, we have isolated two distinct hemoglobins from the symbiont-containing clam gills which react preferentially with either oxygen or sulfide. The differences in reactivity may allow the hemoglobins to achieve a division of labor within the gills, that of delivering oxygen and sulfide to their respective consuming centers. The unusual behaviors of these hemoglobin proteins, either sulfide reactivity or refractiveness, have been characterized at the level of molecular structure. We have employed methods to isolate and purify the hemoglobins to determine molecular size, oligomeric state and amino acid content. Optical spectrophotometry, stopped- flow kinetic analysis and electron paramagnetic resonance spectroscopy are used to measure ligand affinities, reaction rates, oxidation/reduction potentials and heme pocket geometry. Additional work with intact living clam gills has identified several of the oxygen and sulfide reactions with hemoglobin in vivo. We use state-of-the-art in vivo spectrophotometry and respirometry to simultaneously determine the metabolic state of living tissues and the fluxes of oxygen and sulfide. These studies are being expanded to identify accompanying adaptations supporting this symbiotic association, at the levels of cellular specialization, functional morphology and behavioral strategy. These investigations may enhance our understanding of the physiological responses of animals to harsh environments created naturally or by human activity.

Representative Publications:

Kraus, D.W. and J.B. Wittenberg. 1990. Hemoglobins of the Lucina pectinata /bacteria symbiosis. I. Molecular properties. Kinetics and equilibria of reactions of the ferrous proteins with ligands. J. Biol. Chem. 265:16043-16053.

Kraus, D.W., J.B. Wittenberg, J. Lu and J. Peisach. 1990. Hemoglobins of the Lucina pectinata /bacteria symbiosis. II. An electron paramagnetic resonance and optical spectral study of the ferric proteins. J. Biol. Chem. 265:16054-16059.

Kraus, D.W., J.E. Doeller and J.B. Wittenberg. 1992. Hydrogen sulfide reduction of symbiont cytochrome c552 in gills of Solemya reidi (Mollusca). Biol. Bull. 182:435-443.

Kraus, D.W., J.E. Doeller and C.S. Powell. 1996. Sulfide may directly modify hemoglobin deoxygenation in Solemya reidi gills. J. Exp. Biol. 199:1343-1352.

Lee, R.W., D.W. Kraus and J.E. Doeller. 1996. Sulfide-stimulated oxygen consumption rate and cytochrome reduction in gills of the estuarine mussel Geukensia demissa. Biol. Bull. 191:421-430.

Bishop, J.J., T.L. Vandergon, D.B. Green, J.E. Doeller and D.W. Kraus. 1998. A high affinity hemoglobin is expressed in the notochord of amphioxus, Branchiostoma californiense. Biological Bulletin 195: 255-259.

Doeller, J.E., B.K. Gaschen, V. Parrino and D.W. Kraus. 1999. Chemolithoheterotrophy in a metazoan tissue. I. Sulfide supports cellular work in ciliated mussel gills. J. Exp. Biol. 202:1953-1961.

Messer, R.L.W., J.E. Doeller, D.W. Kraus and L.C. Lucas. 2000. An investigation of fibroblast mitochondria enzyme activity and respiration in response to metallic ions released from dental alloys. J. Biomedical Materials Res. 50:598-604.

Doeller, J.E., M.K. Grieshaber and D.W. Kraus. 2001. Chemolithoheterotrophy in a metazoan tissue: thiosulfate production matches ATP demand in ciliated mussel gills. J. Exp. Biol. 204:3755-3764.

Meade, M.E., D. Kraus, J. Doeller and S.A. Watts. 2002. Effects of temperature and salinity on weight gain, oxygen consumption rate, and growth efficiency in the juvenile redclaw crayfish Cherax quadricarinatus. J. World Aquaculture 33:188-198.

Brookes, P.S., S, Shiva, D.W. Kraus, J.E. Doeller, M.-C. Barone, R. P. Patel and V. Darley-Usmar. 2003. Control of mitochondrial respiration by NO°, effects of low oxygen and respiratory state. J. Biol. Chem. (in press).

Return to Graduate Faculty Listing

Graduate Admissions Information

Note DISCLAIMER statement. E-mail: UAB Biology Department WWW Coordinator.