Smithsonian.com

A late-stage tadpole of Xenopus tropicalis on the cover of today's Science (credit: Siwei Zhang, Jingjing Li, Enrique Amaya)

I never found it very shocking that humans and chimpanzees share 96 percent of their genes. After all, chimps are our closest neighbors on the huge family tree of animals. But we also share genes with other organisms, and sometimes this can get pretty surprising (just check out Carl Zimmer’s article from Tuesday’s New York Times).

Scientists have now completed a draft sequence of the frog Xenopus tropicalis and found that the amphibian’s genome contains remarkable similarities to those of the mouse, the chicken and, yes, even the human genome. There are large swaths of DNA that have been conserved through 360 million years of evolution. That was when the last common ancestor of amphibians, birds and mammals lived.

The X. tropicalis frog isn’t the species used most often in lab studies, however. That would be the frog X. laevis. It’s been widely used in research on cell development because of its large eggs and transparent tadpoles (like the one above). But the genome of X. tropicalis is only half the size, so sequencing it was faster and cheaper. And it will still be useful in studies of the Western clawed frog and to sequence that species’ genome all the more quickly.

Why is the frog genome important? It may contain clues to human health: there are at least 1,700 frog genes that, when found in humans, are associated with disease.

Check out the entire collection of Surprising Science’s Pictures of the Week on our Facebook fan page.

Despite common wisdom saying otherwise, melting icebergs do contribute something to sea level rise (courtesy of flickr user winkyintheuk)

When you learned about Archimedes back in elementary school, your teacher probably told you that a floating object displaces an amount of water equal to its own weight. Although an ice cube pokes up out of the water, when it melts, the level of the water should stay the same. Extrapolate this concept to an iceberg floating in the ocean—a bigger version of the ice cube in your water glass—and you would think that melting icebergs shouldn’t contribute to sea level rise. Well, you’d be wrong, say geoscientists at the University of Leeds.

In their study, published this week in Geophysical Research Letters, the researchers used satellite observations and a computer model to assess the impacts of melting icebergs. The total amount of floating ice that is turned into ocean water each year is equivalent to 1.5 million Titanic-sized icebergs. Due to differences in the temperature and density of the ice and water (the seawater is warmer and saltier than the icebergs that float in it), when the icebergs melt, the resulting ocean water is 2.6 percent greater in volume than the volume of water that the iceberg had displaced.

Calculated out, the ocean rises by about 49 micrometers each year due to melting icebergs. That’s not a lot of sea level rise—sea level globally is rising by about 3 millimeters (or 3,000 micrometers) per year—but the scientists say it deserves monitoring.

Elsewhere in news of rising sea levels, Slate profiles an EPA scientist who warns that beaches on the Eastern seaboard are in danger of disappearing. Is it time to abandon beachfront property?

A tiny glint shows where Lunokhod 1 can be found on the Moon (Credit: NASA/GSFC/Arizona State U.)

In “Dark Energy: The Biggest Mystery in the Universe” from the April issue of Smithsonian, writer Richard Panek describes an experiment that measures the distance between the Earth and the Moon:

Twenty times a second, a laser high in the Sacramento Mountains of New Mexico aims a pulse of light at the Moon, 239,000 miles away. The beam’s target is one of three suitcase-size reflectors that Apollo astronauts planted on the lunar surface four decades ago. Photons from the beam bounce off the mirror and return to New Mexico. Total round-trip travel time: 2.5 seconds, more or less.

There are actually five retroreflectors on the Moon: three placed by Apollo astronauts and two that sit atop Soviet rovers. But only one of the Soviet reflectors could be used by astronomers; the other, on board Lunokhod 1, the first robotic rover to traverse the Moon, was lost in 1971. Over the decades astronomers occasionally looked for the rover but without success. Even with the best telescopes it’s difficult to spot something from here on Earth that’s less than eight feet in length; the atmosphere interferes. And Hubble and other space telescopes aren’t able to image the Moon in detail either.

But last month the Lunar Reconnaissance Orbiter imaged the area around Lunokhod 1′s landing site, and a tiny glint could be seen, miles from where scientists had been looking all those years. Was it Lunokhod 1?

Astronomers at the Apache Point Observatory in New Mexico aimed their laser at the glint last week (when the Moon was finally in the right position) and received a return signal. Jackpot! A second observation let them triangulate the reflector’s latitude and longitude. It turns out that the wait may have been worth it: Lunokhod 1 is better positioned for the laser experiments than Lunokhod 2, which does not work well when the Sun shines on it. Lunokhod 1′s return signal was nearly three times as strong as that of Lunokhod 2.

A sample from an oil spill is taken from Alcatraz Island (Credit: NPS/Craig Glassner)

I’ve been thinking a lot lately about oil spills. At the beginning of the month, a Chinese freighter ran aground on the Great Barrier Reef off the coast of Australia, grinding a couple miles coral into dust and leaking oil along the way. A couple of weeks ago came news of a new study showing that oil left behind by the Exxon Valdez disaster 17 years ago can still be found buried in the silt and sand of the intertidal zone, prime feeding territory for a host of wildlife, including sea otters and ducks. Then, last week, an explosion destroyed an oil rig in the Gulf of Mexico and killed 11 workers. The oil pouring from the drill hole—42,000 210,000 gallons per day—has created a slick half the size of Indiana and endangers coastlines from Florida to Louisiana.

The oil company BP has sent robots to plug up the hole—it’s too deep to send divers—but it could be months before the leak stops. At its current rate, the hole would have to spew oil for about 292 58 days to surpass the Exxon Valdez disaster as the largest oil spill in U.S. history. But the Exxon Valdez spill wasn’t all that big in historical terms; it’s only 34th or 35th on the list of the worst spills of all time globally. The current Gulf spill would have to flow for 2,143 429 days to make the top three:

3) July 19, 1979: Two oil tankers, the Atlantic Empress and the Aegean Captain, collided off the coast of Trinidad and Tobago in the Caribbean. The Aegean Captain managed to contain the damage and was towed to port, though it spilled a small amount of oil along the way. The Atlantic Empress, however, was towed out to sea in flames, spilling its oil until it sank on August 3. An estimated 90 million gallons of oil were released into the ocean as a result of the collision.

2) June 3, 1979: The Ixtoc I exploratory oil well off the coast of Mexico in the Gulf blew out and began to leak. When the oil ignited, the platform above collapsed. Attempts to seal the well were unsuccessful until March 23, 1980. A total of 140 million gallons of oil—at a rate of 42,000 to 126,000 gallons per day—was dispersed into the Gulf of Mexico.

1) January 19, 1991: As Iraqi troops left Kuwait, they opened the taps on an offshore oil terminal and several oil tankers, spilling some 380 to 520 million gallons of oil into the Persian Gulf. They created an oil slick 4,000 square miles in size and 4 inches thick. Despite the slick’s record size, a UNESCO report found little lasting environmental damage.

Note: This post was updated on Thursday, April 29 following news that the oil leak was five times worse than originally thought.

A supercomputer can perform the same functions as a cat brain, but it's 83 times slower (photo by Sarah Zielinski)

A University of Michigan computer engineer, Wei Lu, has set out to develop a supercomputer the size of a 2-liter soda bottle that can mimic a cat brain. (Why a cat brain? It’s a more realistic goal than a human brain, he says.)

Mimicking the function of a cat brain is possible with current technology—it just takes a huge supercomputer with its own dedicated power supply. Even then, it’s 83 times slower than a real cat. Why is a real brain so much better as processing information? In part because, unlike a computer that executes code linearly, one piece at a time, a mammalian brain can do many things at once.

The connections in a biological brain also work more efficiently. The synapses that connect neurons can be reconfigured (with interesting consequences for memory), form many different pathways and strengthen them based on the intensity and timing of the electrical signals produced by the various neurons. A traditional transistor in a computer, though, only connects to a few neighbors and doesn’t have any memory of past signals.

Lu’s first step into creating a cat brain computer was to develop a “memristor” that acts more like a biological synapse and has a memory of past voltages to pass through it. He then connected two circuits with his memristor and showed that they system was capable of a type of memory and learning process called “spike timing dependent plasticity.” Lu is still years away from his soda-bottle-sized cat brain dream, however. So if you want a cat brain to figure something out for you, you’ll still need a furry friend.