By HENRY FOUNTAIN
Published: May 4, 1999
Through genetic engineering, plants can become living drug factories, producing antibodies and other proteins for use in pharmaceuticals. But the difficulties and costs involved in extracting and purifying these proteins from plant tissue has prevented the process from being adopted on a large scale.
Researchers from Rutgers University have developed a different way of getting recombinant proteins from a plant: out through the roots. By growing plants in a hydroponic, or water-based, medium rather than soil, it may be possible to harvest the proteins simply and continuously as they are secreted.
The researchers, who described their work in the current issue of the journal Nature Biotechnology, introduced DNA for producing three kinds of foreign proteins into tobacco plants. Fused to the DNA were ''endoplasmic reticulum targeting signals,'' molecular chains that tricked the plant into routing the proteins into its secretory system. The resulting plants secreted large amounts of the proteins through their roots. In plants lacking the targeting signals, the compounds remained in the root cells.
The process, which the researchers call rhizosecretion, should also cut down on purification costs, which are substantial in producing such proteins. Plants secrete relatively few proteins from their roots, so separating the desired protein from the others in the hydroponic solution should be less of a chore.
Sauropod dinosaurs have been depicted as the giraffes of the prehistoric world, holding their long necks in a swanlike curve to browse the treetops for food. Experts have often wondered how the circulatory systems of such dinosaurs could pump blood up to the elevated head, with some suggesting that they must have had multiple hearts to do the job.
But now researchers have determined that sauropods probably didn't have such a haughty posture after all. In fact, the researchers report in the current issue of Science, the dinosaurs' necks -- which reached lengths of up to 40 feet -- were practically straight, sloping gently downward. Rather than dining in the trees, the sauropods probably grazed along or near the ground.
Fossilized bones being too heavy and fragile to manipulate, the researchers, from Northern Illinois University and the University of Oregon, used the next best thing: a computer model. Specifically, they developed software to simulate the neck structure and motion of two species of sauropods, diplodocus and apatosaurus (which used to be known as brontosaurus).
These ''virtual necks,'' when manipulated by computer, showed that sauropods were a lot less limber than previously thought. Diplodocus, in particular, could barely raise its head higher than its back.
Volcano in the Sea
Scientists from the Woods Hole Oceanographic Institution have discovered a major underwater volcano near the Samoa Islands that rises more than 14,000 feet from the ocean floor. It is as if Mount Whitney, the highest peak in the 48 contiguous states, had been plopped down in the middle of the South Pacific.
The location of the volcano had been predicted from a series of earthquakes in the region in 1995. But maps of the sea floor near the island chain, created using altimetry data from satellites, showed only a small hill-like feature. The scientists made a more detailed bottom survey from a research ship that revealed the volcano's true size: about 22 miles across at the base, and rising to within 2,000 feet of the surface. The top is marked by a circular caldera that is about a mile across and 1,300 feet deep.
The discovery lends credence to the idea that the Samoa Islands are, like the Hawaiian Islands, a ''hot spot'' chain, formed as part of the earth's crust slowly migrates across a fixed hot spot, or plume of magma rising through the mantle.
Drawing (Nurit Karlin)