New sky map: Look, Ma, no Milky Way! Milky Way, begone! On a clear night, the starlit swath of our

home galaxy stretches across the sky like a diamond bracelet. But to astronomers trying to look at galaxies beyond our own, the dust and stars of the Milky Way pre- sent a major nuisance, blotting out visible light from some 15 percent of the universe.

Anew sky map provides the first unob scured view of an extensive portion of the heavens. Using the radio telescope in Parkes, Australia, astronomers have im- aged the entire southern sky at the so- called HI radio wavelength emitted by atomic hydrogen gas. Unlike visible light, this radiation passes unimpeded through the Milky Way, revealing the myriad galaxies behind it.

Astronomers had already used this method to peer through the Milky Way’s murk, but the new survey is the first to provide positions and distances of galax- ies and gas clouds over a wide area, out to 500 million light-years. “It certainly gives a better picture of the local uni-

verse,” comments Ofer Lahav of the Uni- versity of Cambridge in England.

Although our galaxy is rich in hydrogen, astronomers can easily distinguish its emissions from those of other galaxies. Cosmic expansion shifts the radio waves emitted by external galaxies to longer wavelengths, notes Lister StaveleySmith of the Australia Telescope National Facil- ity in Epping. His team unveiled the map May 23 in Socorro, N.M., at a meeting on gas and galaxy evolution.

By detecting gas clouds that emit little visible light yet that each weigh as much as several hundred million suns, the team may have found building blocks left over from the formation of the Milky Way and its neighbors, Staveley-Smith says. The study, known as HIPASS (HI Parkes AllSky Survey), thus is yielding a more accurate assessment of the cosmic amount of ordi- nary matter-material made of neutrons and protons-and in turn, the amount of unseen dark matter the cosmos contains, notes Lahav. -R. Cowen

Bright galaxies and gas clouds in the southern sky imaged by H I P M . These galaxies, some newly visible, lie in strings and sheets rather than fill the sky uniformly

Gene therapy grows bone in mice and rats It’s been more than 30 years since sci-

entists discovered bone morphogenetic proteins (BMPs), molecules that spur bone production. After much experi- mentation, tests in people show that BMPs can regrow missing or damaged bone. Some severely injured bone does not respond to this therapy, however, because BMPs need a foundation of liv- ing cells to stimulate bone formation.

Using rats and mice as models, r e searchers at the University of Michigan School of Dentistry in Ann Arbor have now devised a gene therapy that deliv- ers cells making both BMPs and bone it- self. The study suggests a new line of treatment for hard-to-repair fractures or degenerated bone, both of which would otherwise require that surgeons trans- fer, or graft, bone or bone marrow from one part of the body to another, says study coauthor R. Bruce Rutherford, a dental scientist at Michigan.

Rutherford and his colleagues knew that BMPs injected into odd places, such as skin or muscle, could induce

these tissues to make bone. They took skin cells from rats and combined them in a laboratory dish with a geneticallly engineered adenovirus to which the re- searchers had added the gene for a BMP family member called BMP-7. Although the virus can’t replicate, it infects the cells and induces some of them to mass- produce BMP-7 and others to take on the role of bonebuilding cells.

Rutherford and his colleagues added the genetically engineered cells to a mix- ture of protein-rich foam, then applied it to the heads of six rats that had had the tops of their skulls removed. The thera- py spurred bone formation so well that 90 percent of the missing skull bone grew back within a month.

“The rapidity with which it filled in was quite surprising to me,” Rutherford says. Six untreated rats with similar injuries r e grew very little bone, the scientists re- port in the May 20 HUMAN GENE THERAW.

In another BMP-7 experiment, human gum cells treated with the virus in a lab dish launched bone growth in 30 mice.

Top: In this image, which records hydrogen gas from our galaxy and its neighbors, the Milky Way galaxy (arrow) pulls gas from two nearby galaxies (upper left). Bottom: Among the string of dots at the right is a previously unseen gas cloud.

In both experiments, the virus-infect- ed cells stopped making BMP-7 after 2 to 3 weeks. It’s not clear what ends the process, Rutherford says.

The study “represents a new approach for BMPs,” says Pamela G, Robey of the National Institute of Dental and Craniofa- cia1 Research in Bethesda, Md. “There are many [patients] that BMPs by them- selves don’t work on.”

These include people whose broken bones become infected or are heavily scarred, says George H. Rudkin, a plastic surgeon at the University of California, Los Angeles School of Medicine.

The gene therapy might also help cancer patients in whom bone has been removed surgically or has been weakened by radia- tion treatment, which diminishes the num ber of bonemaking cells and limits blood supply to the few remaining, R u m says.

The scientists are trying to reduce the need for bone grafts because the proce dure causes considerable discomfort and can lead to infection. The r e searchers next plan to apply the experi- mental gene therapy to broken thigh- bones in rodents. -A? seppa

JUNE 3,2000 SCIENCE NEWS, VOL. 157 357