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P L A N E T A R Y S C I E N C E

Titanic Lakes of MethaneMethane smog enshrouds Titan, Saturn’s mysterious moon. Because of that smog, researchers have surmised that liquid methane should exist on the surface, but probes had failed to fi nd any. Recent radar imaging by the Cassini space probe, however, has now uncovered 75 lake-like areas, some spanning 70 kilometers, near the northern pole. Scientists believe these to be liquid-fi lled depressions, because the temperature (–179 de-grees Celsius) and pressure (1.5 times that at Earth’s surface) there are ripe for liquid meth-ane and its breakdown product, ethane, to persist. The lakes may fi ll up either from liquid stored underground or through evaporation and subsequent hydrocarbon rain. Future fl ybys should reveal how the lakes vary seasonally, as well as whether lakes exist elsewhere on Titan’s surface. The report appears in the January 4 Nature. —David Biello

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BRIEF POINTS

■ Bovine biotech: researchers have created eight Holstein cattle

that lack the gene for the prion protein, rendering them resistant

to mad cow disease. The animals appear healthy without the gene.

Nature Biotechnology, January 2007

■ Scientists have pinpointed one of the genes manipulated by

Gregor Mendel—specifi cally, the gene that controls the color of pea

seeds. It marks the third of the monk’s seven pea genes

to be precisely identifi ed.

Science, January 5, 2007

■ A ceramic called zircon, envisioned as a container for nuclear waste, appears less

stable than thought. A study fi nds that zircon holding 10 percent by

weight of plutonium 239 would last only 1,400 years, rather than

250,000 years, as was hoped.

Nature, January 11, 2007

■ Not as chimpy: Factoring in the number of gene duplicates

(the gene copy number) and not just the difference in

equivalent genes, humans and chimps only have a 94 percent

genetic similarity.

PLoS ONE, December 20, 2006

ME THANE L AKES dapple Titan’s surface in this false-color radar image taken by the Cassini probe.

L O N G E V I T Y

A Gene for Aging Smartly If you live to 100, as roughly one in every 10,000 people do, you will want both your mind and body intact. A certain gene seems to help accomplish just that. Nir Barzilai of the Albert Einstein College of Medicine and his colleagues examined 158 elderly people of Ashkenazi

Jewish descent. Centenarians who passed a 30-question test were two to three times as likely to have a common variant of the so-called CETP gene as those who did not. Those between 75 and 85 who passed the test were fi ve times as likely. The CETP gene variant leads to larger than normal cholesterol particles in the blood, their size perhaps making them less likely to lodge in the lining of blood vessels, a process that boosts the risk of heart attack and stroke. The fi ndings appear in the December 26 Neurology. —Charles Q. Choi

LONG LIFE and mental acuity may have a genetic connection.

N E U R O S C I E N C E

Back to the FutureThe human mind taps into the same parts of the brain while imagining the future as it does when recollecting the past. Neurosci-entists at Washington University in St. Lou-is put 21 volunteers in a functional magnet-ic resonance imaging machine and asked them to recall or imagine events, such as see-ing themselves at a party with Bill Clinton. Eight different regions displayed extra ac-tivity—that is, increased blood fl ow—when

dealing with imagining the future, including Brodmann’s area, the medial posterior pari-etal cortex and the posterior cerebellum. An additional 15 regions played a role in either remembering the past or imagining the fu-ture, including those previously identifi ed as important for remembering locations al-ready visited. The Proceedings of the Na-tional Academy of Sciences USA published the study online January 1. —David Biello

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