Silkworms have been genetically engineered to produce the valuable medical protein collagen in the fabric of their cocoons.
Silk production is already a major industry in many countries, and there could be significant scope for producing other beneficial proteins in the cocoons, say the Japanese researchers.
Collagen is a connective tissue protein used in reconstructive and cosmetic surgery. Katsutoshi Yoshizato鈥檚 team at Hiroshima University made sure the collagen would only be produced in silk by linking the collagen gene to a switch which normally activates fibroin, a protein expressed exclusively in silk glands.
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They found that collagen was produced alongside the silk, accounting for up to 10 per cent of the protein by weight in the resulting cocoons. It was easy to extract, say the researchers.
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Other teams have genetically modified animals to produce desirable proteins in their milk, and plants to produce them in crops.
Julian Marr, who researches using transgenic plants to produce recombinant proteins at Guy鈥檚 and St Thomas鈥檚 Hospital in London, UK, thinks these approaches have major advantages over silk worms, which produce relatively low yields by weight.
鈥淚t surprises me that people are suggesting using silk worms. With plants you can just grow fields and fields of the stuff,鈥� he told 快猫短视频. 鈥淎nd if you鈥檙e talking about collagen in particular, you can forget about it. For wound healing or grafts you need a lot, and I can鈥檛 imagine colonies of silk worms being able to produce enough.鈥�
However, the silkworms can start producing their threads within six weeks, faster than crops can be grown, or animals raised.
Journal reference: Nature Biotechnology (DOI: 10.1038/nbt771)