New Scientist    1255 GMT, 9 February 2001 

                 Tree of life
                        Gene-altered rubber plants are putting human
                        proteins on tap

                        Human proteins have been produced for the first time in
                        genetically modified rubber plants.

                        The breakthrough offers potential for the cheap harvesting of
                        many therapeutic and industrial proteins from rubber
                        plantations. It was announced on Friday at the "BioVision"
                        conference on biotechnology in Lyon, France.

                        "It's a living bioreactor, and we're getting continuous
                        production simply by tapping it for milk," says Hoong-Yeet
                        Yeang of the Rubber Research Institute of Malaysia in Kuala

                        A gene in Yeang's rubber trees produces human serum albumin,
                        a vital nutrient given to patients on drip feeds in intensive

                        Yeang could not give a precise yield. But he says that the
                        trees produce milligrams of the protein per millilitre of latex,
                        the milky sap from which rubber is made.

                        "Trees produce between 100 and 300 millilitres per tree per
                        tapping, and you can tap every two days, or even daily," he
                        says. With 400 trees per hectare, the harvests could be
                        substantial and extremely cheap, he says.

                        Higher yields

                        He thinks that yields can be raised substantially higher thanks
                        to recent breakthroughs in genetic technology. His team has
                        isolated the gene switches, called promoters, from rubber
                        plants that turn genes on exclusively in the latex.

                        So far the experiments have relied on gene switches from
                        viruses, which are less efficient. "By driving production in latex
                        itself, yield could be significantly improved," he said.

                        Yeang says that such copious yields make it economical to
                        produce industrial proteins as well as valuable
                        pharmaceuticals. "Because rubber trees are so cheap, it can
                        be used to make proteins of moderate value, such as those in
                        shampoos or toothpaste, or enzymes for detergents," he said.

                        And after extracting proteins of value, the rubber could still be
                        sold. So tyres on aircraft could end up being made from the
                        by-products of protein production.

                        Yeang also claimed he has produced antibodies against
                        bacteria in the sap. He says these would be used in a personal
                        care product, such as toothpaste. But he would not give any
                        further details due to the constraints of commercial