American Chemical Society's weekly PressPac -- Jan. 9, 2008

Solving the mystery of the metallic sheen of fish
Crystal Growth & Design

The bright, metallic sheen of fish skin — source of endless fascination for fishermen and aquarium owners — is due to a sophisticated system of crystals that enhance light reflection and may help fish hide from predators in the wild, scientists in Israel are reporting. Their study is scheduled for the current issue of ACS’ Crystal Growth & Design, a bi-monthly journal.

In the new study, Lia Addadi and colleagues note that researchers have known for years that guanine crystals in the skin underneath the scales of fish reflect light to produce a mirror-like sheen. This silvery reflectance acts as a form of camouflage that helps protect fish from predators as fish swim near the water’s surface. However, the exact shape of these guanine crystals and how they work remained a mystery.

The researchers extracted guanine crystals from the skin of the Japanese Koi fish and analyzed the crystals using X-ray diffraction and an electron microscope. They compared the results to guanine crystals made in the laboratory. The researchers found that the biogenic crystals develop in an unexpected direction that differs from the lab-made crystals and that their unique shape improves light reflectivity. The arrangement represents a “strategy evolved by fish to produce more efficient photonic crystals,” the article states. - MTS

ARTICLE #3 FOR IMMEDIATE RELEASE “Biogenic Guanine Crystals from the Skin of Fish May Be Designed to Enhance Light Reflectance”

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CONTACT: Lia Addadi, Ph.D.
Weizmann Institute of Science
Rehovot, Israel
Phone: 972-934-2228
Fax: 972-934-4151
Email:

ARTICLE #4 FOR IMMEDIATE RELEASE

Rice that ‘Snaps, Crackles and Pops’ with Protein
Journal of Agricultural and Food Chemistry

Scientists in the United States and India are reporting development of a high-protein variety of rice, dietary staple for half the world’s population. The study is scheduled for the Jan. 23 issue of ACS’ Journal of Agricultural and Food Chemistry, a biweekly publication.

Researchers have been trying to bolster the protein in rice for five decades. Rice already is a main source of calories as well as protein intake for billions of people, and its enrichment of protein would have a positive impact on millions of poor and malnourished people in developing countries, the report says.

In the study, Hari B. Krishnan and colleagues created a hybrid by crossing a commonly cultivated rice species called Oryza sativa with a wild species, Oryza nivara. The product showed a protein content of 12.4 percent, which is 18 percent and 28 percent higher than those of the parents. The results demonstrate the potential for wild rice’s relatives for boosting the protein content in rice. The researchers conclude that the hybrid could serve as initial breeding material for new rice genotypes that could combine types with superior cooking quality with those of high protein content. - JS