Genetic Engineering Mates With Traditional Breeding To Create New Fibers

Silk’s strength and biocompatibility make the fiber as attractive in biomedical applications as it is in consumer textiles. But the worms that produce the best silk in the largest quantities resist genetic engineering by becoming dormant, a process called diapause, when exposed to gene transfer agents. For that reason, mass-produced transgenic silk has been out of reach. Toshiki Tamura of Japan’s National Institute of Agrobiological Sciences and coworkers have now gotten around the problem by mating nondiapausing silkworms modified to produce fluorescent silk with diapausing varieties (Adv. Funct. Mater. 2013, DOI: 10.1002/adfm.201300365). The resulting offspring produce silks in large quantities that fluoresce green, orange, or red and have 80 to 90% of the strength of commercial silk. The group also developed gentle ways to process the silkworms’ cocoons into usable fiber to avoid denaturing the florescent proteins. The team says this combination of modern and traditional genetic manipulation could allow farmers to produce “functional silks possessing protein sequences that confer unique biological activity” and serve as catalysts or therapeutics.