Michael A. Grusak, Ph.D.
Associate Professor of Pediatrics, Baylor College of Medicine
Plant Physiologist, Agricultural Research Service
E-mail: mgrusak@bcm.edu
Research Interests
Understanding Plant Nutrient Transport to Improve Food Crop Nutritional Quality and Assess Phytonutrient Bioavailability
I am involved in both plant physiology and human nutrition studies. The plant physiology research concerns the long-distance translocation of organic and inorganic nutrients within the phloem and/or xylem system of plants, as well as the short-distance transport of mineral ions across various cellular and organellar membranes. Of major interest is whole-plant micronutrient nutrition (primarily iron and zinc) and the interrelationship of shoot and root factors that homeostatically regulate root micronutrient acquisition and the eventual deposition of micronutrient metals in edible plant parts (e.g., seeds). The long-term goals are to characterize the dynamics of nutrient flow within plants to determine the biophysical/molecular signals that regulate source-to-sink nutrient partitioning and to use these data to develop strategies for enhancing the nutritional quality of plant foods. Methodologies utilized include stable-isotope labeling and whole-plant partitioning analysis, membrane flux analysis using radioisotopes and/or electrophysiology, and molecular techniques to identify and characterize genes and gene products relevant to metal transport and metal homeostasis.
The human nutrition research involves the development of hydroponic and gaseous plant labeling equipment to generate stable isotopically labeled plant foods and bioproducts for human consumption. The labeled foods are used to address questions about the absorption and utilization of specific nutrients. The current emphasis of this research is on the bioavailability of iron, zinc, and amino acids from seed sources, or calcium, selenium, carotenoids, and phylloquinone (vitamin K) from various vegetable sources.
Representative Publications
Tang G, Qin J, Dolnikowski GG, Russell RM, Grusak MA. Spinach or carrots can supply significant amounts of vitamin A as assessed by feeding with intrinsically deuterated vegetables. Am J Clin Nutr. 82(4):821-828, 2005.
Nguyen M, Patuwo T, Grusak MA. Phytic acid (inositol hexaphosphate): screening for low phytic acid concentration in pea seeds for increased bioavailability in humans. Ethn Dis. 15(3 Suppl 4):S4-3-4, 2005.
Abbo S, Molina C, Jungmann R, Grusak MA, Berkovitch Z, Reifen R, Kahl G, Winter P, Reifen R. Quantitative trait loci governing carotenoid concentration and weight in seeds of chickpea (Cicer arietinum L.). Theor Appl Genet. 111(2):185-195, 2005.
Wang HL, Grusak MA. Structure and development of Medicago truncatula pod wall and seed coat. Ann Bot (Lond). 95(5):737-747, 2005.
Tang G, Ferreira AL, Grusak MA, Qin J, Dolnikowski GG, Russell RM, Krinsky NI. Bioavailability of synthetic and biosynthetic deuterated lycopene in humans. J Nutr Biochem. 16(4):229-235, 2005.
Grusak MA. Golden Rice gets a boost from maize. Nat Biotechnol. 23(4):429-30, 2005.
Putzbach K, Krucker M, Albert K, Grusak MA, Tang G, Dolnikowski GG. Structure determination of partially deuterated carotenoids from intrinsically labeled vegetables by HPLC-MS and 1H NMR. J Agric Food Chem. 53(3):671-677, 2005.
Bos C, Stoll B, Fouillet H, Gaudichon C, Guan X, Grusak MA, Reeds PJ, Burrin DG, Tome D. Postprandial intestinal and whole body nitrogen kinetics and distribution in piglets fed a single meal. Am J Physiol Endocrinol Metab. 288(2):E436-E446, 2005.
Finley JW, Grusak MA, Keck AS, Gregoire BR. Bioavailability of selenium from meat and broccoli as determined by retention and distribution of 75Se. Biol Trace Elem Res. 99(1-3):191-209, 2004.
Pomper KW, Grusak MA . Calcium uptake and whole-plant water use influence pod calcium concentration in snap bean plants. J Amer Soc Hort Sci. 129:890-895 2004.
Grusak MA, Rogers RB, Yousef G, Erdman Jr JW, Lila MA. An enclosed-chamber labeling system for the safe 14 C-enrichment of phytochemicals in plant cell suspension cultures. In vitro Cell Develop Biol-Plant. 40:80-85 2004.
Yousef GG, Seigler DS, Grusak MA, Rogers RB, Knight CT, Kraft TF, Erdman JW Jr, Lila MA. Biosynthesis and characterization of 14C-enriched flavonoid fractions from plant cell suspension cultures. J Agric Food Chem. 52(5):1138-1145, 2004.
Lopéz-Millán AF, Ellis DR, Grusak MA. Identification and characterization of several new members of the ZIP family of metal ion transporters in Medicago truncatula. Plant Mol Biol. 54(4):583-596, 2004.
Erkkila AT, Lichtenstein AH, Dolnikowski GG, Grusak MA, Jalbert SM, Aquino KA, Peterson JW, Booth SL. Plasma transport of vitamin K in men using deuterium-labeled collard greens. Metabolism. 53(2):215-221, 2004.
Bos C, Stoll B, Fouillet H, Gaudichon C, Guan X, Grusak MA, Reeds PJ, Tome D, Burrin DG. Intestinal lysine metabolism is driven by the enteral availability of dietary lysine in piglets fed a bolus meal. Am J Physiol Endocrinol Metab. 285(6):E1246-E1257, 2003.
Lienau A, Glaser T, Tang G, Dolnikowski GG, Grusak MA, Albert K. Bioavailability of lutein in humans from intrinsically labeled vegetables determined by LC-APCI-MS. J Nutr Biochem. 14(11):663-670, 2003.
Ibrikci H, Knewtson S, Grusak MA. Chickpea leaves as a vegetable green for humans: evaluation of mineral composition. J Sci Food Agric. 83:945-950 2003.
Ellis DR, Lopéz-Millán AF, Grusak MA. Metal physiology and accumulation in a Medicago truncatula mutant exhibiting an elevated requirement for zinc. New Phytol. 158:207-218 2003.
Wang TL, Domoney C, Hedley CL, Casey R, Grusak MA. Can we improve the nutritional quality of legume seeds? Plant Physiol. 131(3):886-891, 2003.
Grusak MA. Phytochemicals in plants: genomics-assisted plant improvement for nutritional and health benefits. Curr Opinion Biotechnol. 13:508-511 2002.