SWARMING STORMS 

There's no rest for the weary. As the death toll from Sunday's tornado in Joplin, Mo., climbed to 122 Tuesday, another round of severe thunderstorms raked the U.S. heartland, killing at least 13 people in Arkansas, Kansas and Oklahoma. A total of 47 tornadoes were reported across the Southern Plains and Midwest Tuesday — including "several" around Oklahoma City, the AP reports — following 84 reported twisters over the previous two days. Overall, at least 500 people in the U.S. have been killed by tornadoes so far this year, making the 2011 tornado season one of the deadliest in history.

The latest tornado system was born Tuesday afternoon in Oklahoma and Kansas, where it killed at least eight and two people, respectively. Multiple twisters touched down around Oklahoma City and its suburbs during evening rush hour, and a weather-monitoring station in El Reno, Okla., measured winds up to 151 mph. A tornado near El Reno caused a gas leak at an energy plant, CNN reports, and also injured 20 workers at a drilling rig. The storms then churned eastward into Arkansas, killing three more people before moving into Missouri, where residents of devastated Joplin sought shelter from heavy rain, winds and lightning. The city was briefly placed under a tornado warning late Tuesday, just two days after it was razed by the single deadliest American twister on record, although no new tornado damage was reported. One tornado in nearby Franklin County, Ark., grew to nearly a mile wide, however, and was one of many funnel clouds that caused extensive damage Tuesday. "We could see debris in the radar returns we were receiving, and that gave us a good indication the tornado was strong and large," NWS meteorologist Steve Plitz tells CNN. 

It almost seems to go without saying now, but the tornado threat is still not over. The storm system that battered the Southern Plains Tuesday is now moving east-northeast, threatening swaths of the Mississippi and Ohio valleys today and tonight, AccuWeather reports. Heavy rains are expected to dump onto the already-saturated Mississippi River Delta, while cities from Tyler, Texas, to Detroit, Mich., are at risk from damaging thunderstorms until Thursday morning. After that, the system should continue drifting to the east, covering an area from the northern Appalachians to the Gulf Coast.

(Sources: CNN, New York Times, Associated Press, AccuWeather, National Weather Service)

LIVING HAIL 

As violent thunderstorms dump hail across the U.S. this week, a new study reveals that hailstones contain large numbers of bacteria — and it seems to support the idea of "bioprecipitation," which suggests microbes are actively involved in stimulating clouds to precipitate, the BBC reports. According to the study's authors, these bacteria may have evolved to hitch rides in the planet's water cycle, helping the species disperse itself around the environment with minimal effort.

Presented at the American Society for Microbiology's general meeting in New Orleans, the study adds to evidence gathered since the 1960s of microbes living in snow and other precipitation. The bacterium Pseudomonas syringae is often found in many types of precipitation, using a protein on its surface to help it organize nearby water molecules into a "nucleation" site, which causes ice to form at much warmer temperatures than normal. This warm-weather ice damages the cell walls of plants, letting P. syringae feast on the cells' interiors. But only recently have scientists begun to discover a broader use for the bacterium's bizarre lifestyle: hijacking the water cycle for its own reproductive benefit. By evaporating with water and then causing it to freeze at unnaturally high temperatures, P. syringae seems to be using rain, snow and hail to help it spread its genes farther and more efficiently than it could on its own. Lead author Alexander Michaud of Montana State University collected hailstones on the university's campus after a major hailstorm in 2010, and found that while outer layers of the hailstones held relatively few bacteria, the cores were brimming with them. "You have a high concentration of 'culturable' bacteria in the centers, on the order of thousands of per milliliter of meltwater," he told the ASM meeting.

"It's an interesting idea that's been thrown around for decades but only recently has the data accumulated to support it," added Louisiana State University microbiologist Brent Christner, who was also at the meeting. "As a microbiologist, this idea that ... an organism could piggy-back on the water cycle I find just intriguing. We know that biology influcences climate in some way, but directly in such a way as this is not only fascinating but also very important."

(Sources: BBC News, ScienceDaily)

MOCHA AND MICROBES 

While their distant relatives soar through the skies controlling thunderstorms, another type of bacteria has figured out a more down-to-Earth — but not necessarily calmer — survival strategy, Scientific American reports. A newly discovered bacterium called Pseudomonas putida CBB5 can live entirely on caffeine, according to researchers at the University of Iowa, adding yet another innovation to the long list of bacterial breakthroughs.

Also presented at the American Society for Microbiology meeting, the study reveals how the novel bacterium "breaks caffeine down into carbon dioxide and ammonia" from the molecule's building blocks of carbon, hydrogen, nitrogen and oxygen. University of Iowa microbiologist Ryan Summers found these particular bacteria in a flower bed on the university's campus, and while that may seem like an odd place for caffeine-craving microbes, Summers explains that P. putida CBB5 is probably widespread throughout the environment. "Due to the extensive presence of caffeine in the environment, it is not surprising that there are bacteria that can 'eat' this molecule for growth and reproduction," he writes in a summary of his research, noting that previous studies have also detected microbes capable of consuming caffeine. But his research goes a step further, he adds: "This work, for the first time, demonstrates the enzymes and genes utilized by bacteria to live on caffeine."

After Summers and his colleagues isolated the genes they suspected were responsible for P. putida CBB5's caffeine habit, they inserted them into strains of E. coli, which began producing caffeine-digesting enzymes similar to those of P. putida CBB5. In humans, these enzymes could prove useful for developing new medicines to treat heart arrhythmia or asthma, or to increase blood flow, Summers says. The beverage industry may also be interested, Scientific American adds, since the enzymes might help break down excess caffeine during coffee and tea processing.

(Sources: Scientific American, PhysOrg)

TO INFINITY AND BEYOND 

While the crew of NASA's Endeavour space shuttle conducts spacewalks outside the International Space Station this week, engineers back on Earth are busy developing plans to send humans into deep space, CNN reports. On Tuesday, NASA announced it will model a new deep-space vehicle after its recently scrapped Orion Crew Exploration Vehicle, a project aimed at sending astronauts beyond Earth's orbit for the first time since the 1970s.

"We are committed to human exploration beyond low-Earth orbit and look forward to developing the next generation of systems to take us there," NASA Administrator Charles Bolden said Tuesday. The new spacecraft, called the Multipurpose Crew Vehicle (MPCV), can carry up to four astronauts, Bolden said, and will be capable of traveling to the moon or even to Mars. The MPCV will be built by Lockheed Martin, and could begin manned flights as early as 2016. "We hope to have test flights in this decade," says Douglas Cooke, NASA's associate administrator for exploration. "We're not sure when, but certainly as early as possible." 

After completing long-haul trips through the [skipwords]solar[/skipwords] system, the MPCV would splash down into the Pacific Ocean rather than landing like a space shuttle, CNN reports, a touchdown that evokes the old Apollo spacecraft. But the MPCV is much more advanced, Cooke points out. "We would have an abort system, all the way from sitting on the pad, to flying up, up and away," he tells CNN. "The space shuttle has never had that capability." The vehicle is also 10 times safer to launch than the space shuttle, Cooke adds. The shuttle Endeavour is currently on its final flight, scheduled to end on June 1. After that, NASA has just one shuttle left to launch: Atlantis, which is tentatively slated to lift off for the last time in July. 

(Sources: CNN, Space.com)

THIS DAY IN HISTORY

Ralph Waldo Emerson is born, the Lacey Act becomes law, and more.

Russell McLendon

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Photo (tornado damage in Joplin, Mo., on May 24): ZUMA Press

Photo (hailstone): National Oceanic and Atmospheric Administration

Photo (mold growing in coffee mug): Eric_I_E/Flickr

Image (artist's rendering of Multipurpose Crew Vehicle): NASA

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