1995 - Associate Professor, Department of Agronomy, Iowa State University
1994 - Research Director, ExSeed Genetics LLC
1988-1994 Project Leader, Research Department, Zeneca Seeds, US
1981-1988 Senior Research Scientist, Zeneca Corporate Bioscience Lab, UK
I have a career-goal of understanding the biochemistry, molecular biology and genetics of the pathway, control and compartmentation of starch biosynthesis in developing cereal grain. I have filed several biotech patent applications and published many papers in this area over several years. ExSeed Genetics funds selected research programs with US and European universities. The overall aim of our work is to use genetic and biotechnological approaches to improving maize yield, grain quality and yield stability. ExSeed Genetics is based in Ames, Iowa. From 1988 until 1994 I was Project Leader of the Applied Biology Project as well as Group Leader of the Maize Grain Filling and Yield Stability Work Group, Garst Seed Company (part of the Zeneca Seeds Group), based at Slater, Iowa. From 1985 until 1988 I was employed as a Senior Research Scientist, Plant Science Group, Zeneca Seeds, Runcorn, Cheshire, UK. From 1981 until 1985 I was employed as a Senior Research Scientist, Exploratory Plant Science Group, ICI Corporate Bioscience Laboratory, Runcorn, Cheshire, UK. From 1976 until 1981 I was employed as a Research Specialist in the Biochemical Mechanisms Section, ICI Central Toxicology Laboratory, Alderley Park, Cheshire, UK.
SELECTED PUBLICATIONS (goto Full List).
Cao H., Imparl-Radosevich J.M., Guan H., Keeling P.L., James M. and Myers A.M. (1999) Identification
of soluble starch synthase activities of maize endosperm. Plant Physiology 120: 205-215.
Imparl-Radosevich J.M., Nichols D.J., Li P., McKean A.L., Keeling P.L. and Guan H. (1999) Characterization
of Maize Starch Synthases IIa and IIb: SS isoforms can be distinguished based on their kinetic properties Arch
Biochem Biophys 362: 131-138.
Guan, H-P., and Keeling, P. L. (1998) Starch Biosynthesis: Understanding the Functions and Interactions
of Multiple Isozymes of Starch Synthase and Branching Enzyme. Trends in Glycoscience and Glycotechnology 10: 307-319.
Imparl-Radosevich J.M., Li P., Zhang L., McKean A.L., Keeling P.L. and Guan H. (1998) Purification and Characterization
of Maize Starch Synthase I and its Truncated Forms. Arch. Biochem Biophys 353: 64-72.
Harn, C., Knight M., Ramakrishnan, A., Guan, H-P., Keeling, P. L. and Wasserman, B. P. (1998) Isolation
and Characterization of the Ss2 Starch Synthase cDNA Clones from Maize Endosperm. Plant Molec Biol 37: 639-649.
Knight M., Harn, C., Lilley, C.E.R., Guan, H-P., Singletary, G. W., Mu-Forster, C., Wasserman, B.P., and Keeling,
P.L. (1998) Molecular cloning of starch synthase I from Zea mays endosperm and expression in E.coli. The Plant
Journal 14: 613-622.
Lu T-J., Jane J-L., and Keeling P.L. (1997) Temperature effect on retrogradation rate and crystalline structure
of amylose. Carbohydrate Polymers 33: 19-26.
Guan H-P., Li P., Imparl-Radosevich J., Preiss J. and Keeling P.L. (1997) Comparing the properties of Echerichia
coli branching enzyme and maize branching enzyme. Arch Biochem Biophys 342: 92-98.
Singletary G.W., Banisadr R. and Keeling P.L. (1997) Influence of gene dosage on carbohydrate synthesis
and enzymatic activities in endosperm of starch-deficient mutants of maize. Plant Physiology 113: 293-304.
Keeling P.L. (1997) Starch Biotechnology: Technical Barriers to Starch Improvement. In: Starch: Structure
and Functionality. The Royal Society of Chemistry, London.
Denyer K., Dunlap F. Thorbjornsen T., Keeling P.L., Smith A.M. (1996) The major form of ADP-glucose pyrophosphorylase
activity in Maize (Zea Mays L.) endosperm is extra-plastidial. Plant Physiology 112: 779-785.
Ball S., Guan H-P., James M., Myers A., Keeling P.L., Mouille G., Buleon A., Colonna P., and Preiss J. (1996)
From glycogen to amylopectin: a model explaining the biogenesis of the plant starch granule. Cell 86: 349-352.
Mu-Forster, C., Huang, R., Powers, J.R., Harriman, R.W., Knight, M., Singletary, G. W., Keeling, P. L. and
Wasserman, B. P. (1996) Physical Association of starch biosynthetic enzymes with starch granules of maize endosperm:
Granule-associated forms of starch synthase I and starch branching enzyme II. Plant Physiology 111: 821-829.
Zehr BE, Eckhoff SR, Nyquist WE, and Keeling P.L. (1996) Heritability of product fractions from wet milling
and related properties of maize grain. Crop Sci 36: 1159-1165.
Eckhoff SR, Singh SK, Zehr BE, Rausch KD, Fox EJ, Mistry AK, Haken AE, Niu YX, Zou SH, Buriak P, Tumbleson ME and
Keeling P.L. (1996) A 100 g laboratory scale corn wet milling procedure. Cereal Chemistry 73: 54-57.
Lu T-J., Jane J_L., Keeling PL., and Singletary GW. (1996) Effects of ear developmental temperature on maize
starch fine structure. Carbohydrate Research 282: 157-170.
Hylton C.M., Denyer K., Keeling P.L., Chang M-T., and Smith A.M. (1996) The effects of waxy mutations on
the granule-bound starch synthases of barley and maize endosperms. Planta 198: 230-237.
