Science: Update

HUMAN EMBRYONIC stem cells are not covered by the United States's ban on state funding for human embryo research, the US National Institutes of Health has declared. The legal opinion, issued earlier this week, is an important milestone for US scientists aiming to investigate the possible benefits of stem cells, for example to grow new organs for adults. The ban defines an embryo as an "organism" - which stem cells, being individual elements, are not, the NIH declared.

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DOLLY THE sheep was the success; but many attempts to clone animals or produce them by in-vitro fertilisation (IVF) have resulted in very large foetuses which did not survive in the womb. Now, teams in the US and Scotland have found that levels of IGF-2, a protein which promotes growth, were much higher in the livers of cow foetuses produced by IVF rather than artificial insemination. "It suggests that the IVF procedure somehow reprogrammes the IGF-2 gene," Patrick Blondin of North Carolina State University told New Scientist magazine.

UNDERGROUND VOLCANIC activity on ancient Mars sculpted gorges far larger than the Grand Canyon in the United States, and melted enough water to create floods of biblical proportions, according to two British geologists.

Dan McKenzie and Francis Nimmo at Cambridge University suggest that huge wedges of molten rock - known as dikes - stretched the surface, and also melted vast amounts of ice, causing colossal floods thought to have scoured Mars's surface between two and three billion years ago.

The theory, put forward in Nature, suggests that some water could have been trapped underground to provide the sort of warm, moist oases where other scientists have suggested that life could have survived.

SETI, THE Search for Extraterrestrial Intelligence, has begun looking for visible signs of alien life. Previously, groups working for Seti have relied on listening for radio messages - often in the so-called "hydrogen band" at microwave frequencies. But the new initiative at the University of California, Berkeley, and the Smithsonian Observatory in Cambridge, Massachusetts, will use optical telescopes. One will look for short pulses of light, as brief as a billionth of a second, from nearby stars while the other will look for steady, extremely narrow band laser pulses, or single-colour light signals.