Portion of Plant Enzyme May Mimic Taxol
Researchers interested in increasing plant cells' use
of carbon for seed storage products like starch, oil, and protein have
been studying sucrose synthase. This enzyme metabolizes sugar and delivers
carbon for plant cell growth and other uses. As a tool, the scientists
fashioned a synthetic peptide, called SS2, from a portion of the enzyme.
They used SS2 to identify regions of sucrose synthase that bind to actin,
a filamentous protein that's part of the cytoskeleton used by plant
cells when dividing and elongating.
They found that SS2 caused actin filaments to clump togetheror
bundlewhich stopped plant cells from dividing. Bundling is similar
to how taxol checks the spread of some human cancer cells. A patent
has been filed for SS2, and a licensing partner's being sought to investigate
the peptide's potential medical applications.
Steven C. Huber,
USDA-ARS Photosynthesis Research
Unit, Urbana, Illinois; phone (217) 265-0909.
Eggs and Eye Health
While chicken eggs are best known for their high-quality protein and
widespread use in bakery and other food products, they are also an excellent
source of lutein. Low lutein intake has been implicated as a risk factor
in age-related macular degeneration, the leading cause of vision loss
among older Americans. The macula is located in the retina, behind the
pupil, and is responsible for central vision. Lutein and another carotenoid,
zeaxanthin, accumulate within the macula and impart a yellow pigment
that helps protect the eye.
Now scientists have found that the lutein present in eggs is more readily
absorbed into the bloodstream than lutein from other sourcespossibly
because of components in the egg's yolk, like lecithin. Their research
showed that the concentration of lutein in volunteers' blood serum was
three times greater after eating eggs than after consuming the same
amount of lutein from other sources, including cooked spinach and two
types of lutein supplements.
Elizabeth J. Johnson,
Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts University, Boston, Massachusetts; phone
Basic Self-Defense for Plants
No one has really understood how plants orchestrate quick, protective
responses to pest attacks, wounds, and other stresses. Now a simple,
accurate method has been devised that uses readily available chemicals,
standards, and instruments to shed light on these processes. The new
protocol simultaneously analyzes interactions between multiple plant
hormones, fatty acids, pathogen-derived elicitors, and other volatile
The method gives physiologists a rapid way to examine how plants use
complex phytohormone interactionscalled "signaling crosstalk"to
coordinate growth, development, and dynamic responses to stress. It
uses vapor phase extraction techniques to collect the phytohormones
and other metabolites from just a few milligrams of plant tissue, gas
chromatography to separate components within the sample, and mass spectrometry
to analyze and measure target compounds.
Eric A. Schmelz,
USDA-ARS Center for Medical, Agricultural,
and Veterinary Entomology, Gainesville, Florida; phone (352) 374-5858.