Ames, Iowa
December 23, 2008
Researchers at
Iowa State University have
used a Nobel Prize-winning genetic technology to expand the
understanding of milling corn.
When corn is milled, or ground, its three primary tissues
combine. That complicates matters for end-users who want
separate parts, such as the protein-and oil-rich part for feed
or the starch for making alcohol.
If only the embryo, starch-rich endosperm or the pericarp
covering the kernel could be made to stand out in the ground
corn it would be easier to select the tissues of interest.
Scientists did just that by developing tissue markers for
transgenic corn lines using green fluorescent protein (GFP).
Geneticist Paul Scott, who works in the U.S. Department of
Agricutlure’s Agricultural Research Service (ARS) Corn Insects
and Crop Genetics Research Unit located at Iowa State; Lawrence
Johnson, director of the Center for Crops Utilization Research;
Kan Wang, director of the Plant Transformation Facility; Charles
Glatz, professor of chemical and biological engineering and
former interdepartmental genetics graduate student Colin
Shepherd, teamed up for the corn project.
“We developed a tool to allow us, for the first time, to
quantify directly the amounts of germ (embryo) and endosperm in
milled products,” Johnson said.
Previously, an analysis was indirect; based on oil content.
Researchers assumed that most of the oil is in the embryo. The
direct measurement using the GFP technology made it possible to
more accurately measure contamination of these tissues in the
different milled products.
“Once you have a means to measure the different parts then you
could use the data to improve the milling process,” Johnson
said. “The changes could include adjusting grain tempering time,
degerminator selection, roller mill settings and sieve sizes.”
The scientists incorporated the GFP markers into the either the
embryo or the endosperm and used a device that measured
lightwave emissions from the fluorescent corn tissues. One corn
line’s endosperm contained 100 percent of the GFP fluorescence.
After hand-dissecting the transgenic kernels and identifying GFP
concentrations in the pericarp, embryo and endosperm tissues,
they had baseline levels to use for identifying different
tissues during the fractionation, or milling, process. The
researchers determined GFP fluorescence levels for each part by
being able to easily identify the mix of tissues in each.
“The GFP technology has revolutionized biology,” Scott said. “It
helps us understand how transgenes function and allows us to
implement transgenic technology in a safer way.” He expected
that it will expand knowledge about how corn genes interact with
genes introduced into corn plants.
The three researchers who developed the GFP technology used by
Scott and his colleagues were presented the Nobel Prize in
chemistry Dec. 10. Osamu Shimomura, Marine Biological Laboratory
and Boston University Medical School; Martin Chalfie, Columbia
University, and Roger Y. Tsien, Howard Hughes Medical Institute,
University of California, isolated the protein from a species of
jellyfish. |
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