Texas A&M University Department of Biology
  • B.S., 1975, University of Calfornia, Davis, Zoology.
  • Ph.D., 1980, University of California, Berkeley, Zoology.
  • Postdoctoral research: University of Alberta.

Joined the department in 1983.

Duncan MacKenzie

Duncan MacKenzie
Associate Professor of Biology
Associate Director for Undergraduate Research, Honors and Undergraduate Research
Co-Chair, Graduate Marine Biology Interdisciplinary Degree Program

3258 TAMU
College Station, TX 77843-3258

Biological Sciences Building East
Room 306E

Biological Sciences Building East
Room 306

Fax: 979-845-2891
Email: duncan@bio.tamu.edu

Curriculum Vitae

Comparative Endocrinology of Thyroid Function

Hormones secreted by the thyroid gland are of primary importance in the regulation of such fundamental physiological processes as growth, nutrient utilization, and reproduction. In my laboratory we examine the regulation of the secretion of thyroid hormones and their actions in poikilothermic vertebrates in order to understand the evolution of thyroid function. We are presently focusing on the regulation on thyroid hormone secretion and the mechanisms of iodine transport in commercially-important fish species such as the red drum (Sciaenops ocellatus), the channel catfish (Ictalurus punctatus), and even the zebrafish (Danio rerio).

We have discovered that blood thyroxine levels undergo robust daily cycles in the red drum, supporting a role for an endogenous clock in the central control of thyroid hormone production. Current studies are directed towards examining the regulation of thyroid hormone cycles and determining their physiological significance. I am also interested in the specific mechanisms through which nutrient intake influences thyroid hormone secretion and the manner in which thyroid hormone delivery to target tissues is influenced by circulatory factors unique to poikilotherms.  Thyroid hormone studies have led us to an examination of the mechanisms through which euryhaline fish obtain iodine from their environment.  We are currently examining the physiology of iodide transport in fish and hope to integrate it into a better understanding of the maintenance of thyroid homeostasis in variable marine environments.

A comparative perspective is always maintained in my research. Because of their position at the transition to endothermy, reptiles remain an interesting model for the examination of thyroid hormone action. For this reason, I also direct research on endocrine function in reptiles, such as sea turtles, desert tortoises, and alligators. From these animals we gain a broader perspective of the relationship between nutrient intake, temperature, and thyroid hormone production.

This research is aimed at providing new insights into the potentially ancient role of thyroid hormones in nutrient assimilation, as well as elucidating evolutionary trends in the regulation of thyroid function. These studies may serve identify ways in which the pituitary-thyroid axis may be manipulated to enhance aquaculture production or endangered species conservation.

  1. Pasupuleti S, Sule N, Cohn WB, MacKenzie DS, Jayaraman A & Manson MD (2014) Chemotaxis of Escherichia coli to norepinephrine (NE) requires conversion of NE to 3,4-dihydroxymandelic acid. J Bacteriol 196:3992-4000 Full text
  2. Martinez B, Soñanez-Organis JG, Vázquez-Medina JP, Viscarra JA, MacKenzie DS, Crocker DE & Ortiz RM (2013) Prolonged food deprivation increases mRNA expression of deiodinase 1 and 2, and thyroid hormone receptor β-1 in a fasting-adapted mammal. J Exp Biol 216:4647-54 Full text
  3. Jones RA, Cohn WB, Miller TC, Jaques JT & Mackenzie DS (2013) Cyclic mRNA expression of thyrotropin subunits and deiodinases in red drum, Sciaenops ocellatus. Gen Comp Endocrinol 194:248-56 Full text
  4. Pohlenz C, Buentello A, Miller T, Small BC, MacKenzie DS & Gatlin DM 3rd (2013) Effects of dietary arginine on endocrine growth factors of channel catfish, Ictalurus punctatus. Comp Biochem Physiol A Mol Integr Physiol 166:215-21 Full text
  5. Browning ZS, Wilkes AA, Mackenzie DS, Patterson RM & Lenox MW (2013) Using PET/CT imaging to characterize 18 F-fluorodeoxyglucose utilization in fish. J Fish Dis 36:911-9 Full text
  6. Miller TC, Jaques JT, Szkudlinski MW & Mackenzie DS (2012) Thyrotropic activity of recombinant human glycoprotein hormone analogs and pituitary mammalian gonadotropins in goldfish (Carassius auratus): insights into the evolution of thyrotropin receptor specificity. Gen Comp Endocrinol 177:70-5 Full text
  7. Celli A, Mackenzie DS, Zhai Y, Tu CL, Bikle DD, Holleran WM, Uchida Y & Mauro TM (2012) SERCA2-controlled Ca²+-dependent keratinocyte adhesion and differentiation is mediated via the sphingolipid pathway: a therapeutic target for Darier's disease. J Invest Dermatol 132:1188-95 Full text
  8. Rodriguez-Martin M, Martin-Ezquerra G, Man MQ, Hupe M, Youm JK, Mackenzie DS, Cho S, Trullas C, Holleran WM, Radek KA & Elias PM (2011) Expression of epidermal CAMP changes in parallel with permeability barrier status. J Invest Dermatol 131:2263-70 Full text
  9. Scobell SK & Mackenzie DS (2011) Reproductive endocrinology of Syngnathidae. J Fish Biol 78:1662-80 Full text
  10. Martin-Ezquerra G, Man MQ, Hupe M, Rodriguez-Martin M, Youm JK, Trullas C, Mackenzie DS, Radek KA, Holleran WM & Elias PM (2011) Psychological stress regulates antimicrobial peptide expression by both glucocorticoid and β-adrenergic mechanisms. Eur J Dermatol 21 Suppl 2:48-51 Full text

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