Christopher A. Loretz, Ph.D.

Associate Professor of Biological Sciences
Endocrine Physiology

Office & Laboratory:

647 Hochstetter Hall
Amherst Campus

Phone:

(716) 645-2363 ext. 182

Fax:

(716) 645-2975

E-mail:

loretz at buffalo dot edu

Mailing Address:

Department of Biological Sciences
109 Cooke Hall
University at Buffalo
Buffalo, NY 14260-1300 U.S.A.

Research Interests

Successful osmotic regulation and nutrient acquisition in vertebrates depend on the vectorial transport of ions, water, and nutrient molecules across epithelial tissues separating the interior of an animal from the exterior. Current research interests center on the mechanisms of transport and on how these processes are regulated in response to ionic and osmotic factors and to nutritional demands of the organism. Euryhaline teleost fish are especially good study systems in this regard since they display remarkable adaptations to fluctuations in environmental salinity and diet. A variety of molecular biological, endocrine, electrophysiological, and analytical techniques are routinely used in the laboratory. Work presently focuses on two major topics: the molecular physiology of the extracellular calcium-sensing receptor in endocrine and ion-transporting cells of fishes, and the regulation of transepithelial transport by natriuretic peptides.

1. Molecular physiology of the piscine extracellular calcium-sensing receptor

Regulation of calcium homeostasis occurs independently from NaCl homeostasis, and involves a suite of endocrine factors. The extracellular calcium-sensing receptor (CaR; a member of the 7-transmembrane domain, G-protein-coupled receptor family including CaR, pheromone receptors, and metabotropic glutamate receptor) is a calcium sensor in hormone-secreting cells. The structure, tissue distribution and expression of CaR and CaR-related proteins in teleost fishes is under study.

2. Regulation of intestinal transport by natriuretic peptides

Natriuretic peptides (NP) are synthesized and secreted from several sites in fishes including the heart and, importantly, the intestinal tract where NPs are potent paracrine inhibitors of NaCl absorption. NPs may also have coordinating effects on salinity-dependent drinking and branchial ion transport, and serve a protective function for the vascular system. NP synthesis and secretion, and structure-activity relationships are being explored.

3. Best practices for international research experiences for undergraduates

Development of a globally competent workforce for the twenty-first century is of national importance as scientists and engineers increasingly look beyond the borders of this country in furthering their scholarly work. I directed the production of a best practices manual for the design, implementation and management of international research experiences for undergraduates that will facilitate the development and improve the quality of these science and engineering students.

Selected References

Takei, Y., and C.A. Loretz 2005

Endocrinology. In: The Physiology of Fishes, 3rd Edition (D.H. Evans and J.B. Claiborne, eds.), CRC Press, Boca Raton, pp. 271-317 (In Press).

Loretz, C.A. 2005

The carboxyterminal-truncated extracellular calcium-sensing receptor in teleosts possesses essential functional domains. Abstracts of the 15^th International Congress on Comparative Endocrinology, Boston, MA, May 22-27, 2005 [PDF]

Loretz, C.A. 2005

Science policy in the U.S. (2004 Shonan Lecture). In: Kagaku ni okeru Shakai Ritarashii 2 (Social Literacy in Science 2) (K. Hirata, ed.), Graduate University for Advanced Studies, Hayama, Japan, pp.165-191 (ISBN 4-901598-05-8). [PDF]

Loretz, C.A. 2005

JSPS international activities build strong ties. Gakujutsu Geppo (Japanese Scientific Monthly) 58(1):54. [PDF]

Loretz, C.A., C. Pollina, S. Hyodo, Y. Takei, W. Chang and D. Shoback 2004

cDNA cloning and functional expression of a Ca²⁺-sensing receptor with truncated carboxyterminal tail from the Mozambique tilapia (Oreochromis mossambicus). J. Biol. Chem. 279:53288-53297. First published on September 29, 2004; 10.1074/jbc.M410098200 [On-line Link]

Shoback, D.M., C. Pollina, W. Chang, S. Pratt, S. Hyodo, Y. Takei and C.A. Loretz 2004

Ca²⁺-sensing receptor of Mozambique tilapia: cDNA expression, signal transduction and salinity-dependent mRNA expression in vivo. J. Bone Miner. Res. 19 (Suppl. 1):S196. [PDF; scroll to abstract number SA545 on page S196]

Loretz, C.A., C. Pollina, S. Hyodo and Y. Takei 2004

cDNA cloning of Mozambique tilapia (Oreochromis mossambicus) extracellular Ca²⁺-sensing receptor: primary structure and tissue distribution. In: Trends in Comparative Endocrinology 2004 (T. Oishi, K. Tsutsui, S. Tanaka and S. Kikuyama, eds.), Asia and Oceania Society for Comparative Endocrinology, pp. 135-137. [PDF]

Pollina, C., W. Chang, S. Pratt, D. Shoback, S. Hyodo, C.A. Loretz and Y. Takei 2004

Ca²⁺-sensing receptor of Mozambique tilapia: functional cDNA expression in cell culture and salinity-dependent mRNA expression in vivo. In: Trends in Comparative Endocrinology 2004 (T. Oishi, K. Tsutsui, S. Tanaka and S. Kikuyama, eds.), Asia and Oceania Society for Comparative Endocrinology, pp. 354-356. [PDF]

Loretz, C.A. 2003

Natriuretic peptides as physiological regulators of membrane transport in the fishes. Proc. Japan Soc. Comp. Endocrinol. 18:6. [PDF]

Pollina, C., S. Hyodo, C.A. Loretz and Y. Takei 2003

Extracellular calcium-sensing receptor of tilapia (Oreochromis mossambicus): cDNA sequence and tissue expression. Proc. Japan Soc. Comp. Endocrinol. 18:42. [PDF]

Loretz, C.A. 2003

NSF Activities in Japan. Science Next Wave, 19 September 2003. Published on-line at: http://nextwave.sciencemag.org/cgi/content/full/2003/09/17/5

Loretz, C.A. 2003

The natriuretic peptide system in fishes: cyclic GMP-coupled regulation. Comp. Biochem. Physiol. A 134 (Suppl. 1):S45. [On-line Link; scroll to article number 12.1]

Loretz, C.A. (Editor) 2002

Looking Beyond the Borders: A Project Director's Handbook of Best Practices for International Research Experiences for Undergraduates, 102 pp. [HTML/PDF]

Loretz, C.A. 2001

Drinking and alimentary transport in teleost osmoregulation. In: Perspective in Comparative Endocrinology: Unity and Diversity (H.J.Th. Goos, R.K. Rastogi, H. Vaudry and R. Pierantoni, eds.), Monduzzi Editore, Bologna, pp.723-732. [PDF]

Loretz, C.A., and C. Pollina 2000

Natriuretic peptides in fish physiology. Comp. Biochem. Physiol. A 125:169-187. [On-line Link]

Loretz, C.A., C. Pollina, H. Kaiya, H. Sakaguchi and Y. Takei 1997

Local synthesis of natriuretic peptides in the eel intestine. Biochem. Biophys. Res. Comm. 238:817-822. [On-line Link]

Loretz, C.A., and Y. Takei 1997

Natriuretic peptide inhibition of intestinal salt absorption in the Japanese eel: physiological significance. Fish Physiol. Biochem. 17:319-324. [On-line Link]

Loretz, C.A., and Y. Takei 1997

Stimulated local release of natriuretic peptides by intestine of the Japanese eel. In: Advances in Comparative Endocrinology (S. Kawashima and S. Kikuyama, eds.). Monduzzi Editore, Bologna, pp. 1221-1224. [PDF]

Loretz, C.A. 1996

Inhibition of goby posterior intestinal ion absorption by natriuretic peptides and by cardiac extracts. J. Comp. Physiol. B 166:484-491. [On-line Link]

Romano, L.A., C.A. Loretz and C.R. Fourtner 1996

Potassium channels in pituitary cells in the teleost, Gillichthys mirabilis. Comp. Biochem. Physiol. A 113:143-156. [On-line Link]

Loretz, CA. 1995

Electrophysiology of ion transport in teleost intestinal cells. In: Fish Physiology, Volume 14, Cellular and Molecular Approaches to Fish Ionic Regulation (C.M. Wood and T.J. Shuttleworth, eds.). Academic Press, Orlando, pp. 25-56. [On-Line Link]

Loretz, C.A. 1995

Atrial natriuretic peptide regulation of vertebrate intestinal ion transport. Amer. Zool. 35:490-502.

Chang, W., and C.A. Loretz 1993

DPC blockade of transepithelial chloride absorption and single anion channels in teleost urinary bladder epithelium. Am. J. Physiol. 265:R66-R75. [On-line Link]

Courses Taught

Evolutionary Biology (BIO 200) (Access to registered students through UBLearns)

This introductory level lecture and laboratory course for department majors and others presents evidence for evolution, and introduces students to: principles of genetics; population genetics; natural selection; sexual and kin selection; evolution of major groups of organisms; speciation; adaptation; coevolution; and sociobiology.

Physiology (BIO 328) (Access to registered students through UBLearns)

This is a general physiology course designed to introduce upper division undergraduate students to basic principles of physiology. Major organ, tissue, and cellular systems of both animals and plants are considered in this comprehensive introduction.

Physiology Laboratory (BIO 338)

Physiology Laboratory complements the corresponding Physiology Lecture (BIO 328) by providing hands-on laboratory experiences designed to demonstrate important physiological concepts. This is a rigorous course emphasizing all aspects of laboratory research: set-up, data collection and analysis, and report writing.

Advanced Physiology (BIO 413/513)

Advanced Physiology is designed to present principles of physiological regulation at an advanced level (upper division undergraduate/beginning graduate). The course relies on the students' satisfactory completion of courses in general physiology, cell biology, and biochemistry. Lecture and discussion will be framed around topics of current interest, and reading materials will include selections from the primary literature.

Endocrinology (BIO 448)

This endocrinology course is an introduction to the biology of chemical mediation at the organismal and cellular levels. Whereas emphasis will be on the regulation of physiological and other processes in vertebrates (especially mammals), lectures and readings are designed to present principles and concepts applicable to other taxonomic groups as well.

Great Discoveries in Science (UGC 302-303)

This course, designed for non-science majors at the University, presents a historical overview of major paradigms in biology. Topics include molecular biology, cell biology and evolutionary biology.