Prenatal Smoking and Crime

Women who smoke when they are pregnant may not only be endangering the physical health of their babies--they also may be more likely to give birth to sons who go on to become criminals.

Jari Tiihonen of the University of Kuopio in Finland and colleagues collected detailed information about 5,636 males and their mothers from when the women were six months pregnant until the children were 28 years old.

Sons of mothers who smoked during pregnancy were more than twice as likely to go on to commit a violent crime or repeatedly commit crimes compared with the sons of women who did not smoke, the researchers report in the June issue of the American Journal of Psychiatry.

The researchers could not explain the findings by examining whether the women who smoked were also more likely to engage in antisocial behavior. The researchers speculated that smoking during pregnancy may affect the chemistry of the developing baby's brain.

Fire's Environmental Effects

Two studies cast new light on how fire affects the natural world.

Jon E. Keeley of the U.S. Geological Survey and colleagues analyzed wildfire records for California dating to 1910. The frequency of fires and the amount of land burned had not changed significantly and the size of fires has not increased, the researchers report in the June 11 issue of Science.

The findings challenge the idea that efforts to control fires have made wildfires worse when they do occur because of the accumulation of brush.

Meanwhile, U.S. and Brazilian researchers found that fires had become so common in the Amazonian rain forest that nearly 50 percent of the remaining forest has burned to some extent. By studying certain forest plots since 1996, the researchers determined that once an area has been burned it becomes much more vulnerable to another fire.

"Left unchecked, the current fire regimen will result in an inexorable transition of the entire areas to either scrub or grassland. Efforts on the regional climate, biodiversity, and the economy are likely to be extreme," they write in the same issue of Science.

Treating Genetic Nerve Disorder

Immature brain cells injected into the brains of mice with a genetic nerve disorder appeared to spread throughout the animals' brains and correct the problem, raising hopes the approach may help treat diseases such as Alzheimer's in people.

Evan Y. Snyder of Harvard Medical School and colleagues injected neural stem cells into the brains of "shiverer mice." These mice develop severe tremors by the age of two or three weeks because they are born with a genetic defect in a protein called myelin, which forms the protective covering of nerve fibers.

The cells migrated throughout the brains of the mice and matured into cells called oligodendrocytes, which produce myelin, replenishing levels of the missing protein, the researchers report in the June 8 Proceedings of the National Academy of Sciences. More important, the mice appeared healthier and tests showed that nearly two-thirds of the animals showed at least a 50 percent reduction in their tremors.

Researchers have been experimenting with injecting brain cells into the brains of humans with diseases that affect very specific parts of the brain, such as Parkinson's. But it had been thought unlikely that such an approach could be used for diseases that affect the brain globally, such as Alzheimer's.

Two Additions to Periodic Table

Physicists have discovered two new elements to add to the periodic table.

Researchers at the Lawrence Berkeley National Laboratory in California found element 118 and element 116 by using the lab's 88-inch cyclotron to bombard targets of lead with an intense beam of high-energy krypton ions.

Both elements are extremely heavy, short-lived and radioactive. Element 118 contains 118 protons and 175 neutrons in its nucleus. By comparison, the heaviest element found in nature in sizable quantities is uranium, which contains 93 protons and 146 neutrons.

Element 118 decays within less than a millisecond after its creation, leaving behind element 116, which contains 116 protons and 173 neutrons in its nucleus, which also decays almost immediately.

"Our unexpected success in producing these super-heavy elements opens up a whole world of possibilities using similar reactions: new elements and isotopes, tests of nuclear stability and mass models, and a new understanding of nuclear reactions for the production of heavy elements," says Ken Gregorich, a nuclear chemist who was part of the team that made the discovery.

Encryption Technique Updated

Molecular biologists have updated a technique used by German spies during World War II to send secret messages.

Catherine Taylor Clelland of the Mount Sinai School of Medicine in New York and colleagues figured out a way to hide a secret message in the chemical sequences of human DNA and then conceal it on the period at the end of a sentence in an ordinary letter.

During World War II, German spies shrank a photograph of a typewritten page containing secret information down to the size of a period at the end of a sentence, pasted it into an innocent-looking letter and dropped it in the mail.

Clelland and her colleagues synthesized a strand of DNA in the laboratory with an encoded message that spelled out "June 6 Invasion: Normandy" and mixed it with a sample of human DNA with markers flanking the message so it could be located and deciphered later. They then placed the DNA on a period in a letter and mailed it to themselves to see if it would survive the U.S. Postal Service. It did.

"Our technique could . . . be used in a similar way to the original microdots: to enclose a secret message in an innocuous letter," the researchers write in the June 10 issue of Nature.