Discovery

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Archive for the ‘Biological sciences’ Category

The Slime that Saves the Planet

Washington State University researchers have received half a million dollars to study a microscopic slime that they believe plays an outsized role in life on the planet.

The slime, also known as biofilm, forms a super-thin layer gluing the roots of plants to mineral surfaces and serves as a reactor in which a plant can break down the rock for vital nutrients. The process, says Kent Keller, was central to the start of land-based plant life as plants invaded the continents 350 million years ago. It continues to take place on modern volcanic ground and receding glaciers—anywhere a plant can’t get enough to eat.

A special root slime helps plants like this pine tree pull nutrients from bare rock. Flickr photo courtesy of eviltomthai.

“The magic of all of this is plants come in that are adapted to make the slime,” says Keller, co-director of the Center for Environmental Research, Education, and Outreach (CEREO) and professor in the School of Earth and Environmental Sciences. “Within 100 years, you’ve got soil. That’s an amazing thing. And it’s these slimes that are a key part of the mechanism.”

Wait, there’s more: The biofilm reactor also facilitates the most fundamental process on the planet for packing away carbon, as seen in the greenhouse gas carbon dioxide. As the plant dissolves minerals, the plant’s natural carbonic acids, made from CO2 through photosynthesis, are transformed into bicarbonate that is carried in runoff to the oceans. There it precipitates as calcium carbonate.

In other words, the biofilm acts as an intermediary between carbon from the atmosphere and its storage in the earth’s crust. Absent that process, carbon dioxide would continue building up in the atmosphere until oxygen-dependent life forms suffocated in a “runaway greenhouse.”

“Without that we wouldn’t be here,” says Keller. “We’d be Venus, because Venus has no mechanism to sequester volcanic CO2.”

But there’s a mystery to the process, which Keller and a group of colleagues will explore with $492,000 from the National Science Foundation. Somehow plants employ biofilms to build up nutrients for plants to use while also releasing them for long-term storage, and they’ve done this in a way in which plants thrive and the chemistry of oceans and the atmosphere is kept in balance.

The researchers—a team of earth, life, and soil scientists—plan to grow trees in different nutrient conditions, including pure sand, to see which are best at inducing the formation of biofilm. One indicator of that will be microbial communities, which essentially generate the biofilms for shelter. The researchers hypothesize that plants in the worst conditions will be predisposed to hosting the most diverse microbial communities, the better to generate slime and nutrients.

One experiment will rely entirely on fertilized irrigation as a proxy for conventional agriculture, which is less reliant on large microbial communities for nutrients. Comparing this system with those generating their own nutrients could help open the door to agricultural systems that can use fewer artificial fertilizers.

The Invention of Sliced Bread Has Nothing on This

Let’s just indulge in a brief moment of bluster and say that Washington State University researchers are on the cusp of what could be one of the greatest inventions since not only sliced bread, but the dawn of agriculture.

Writing in the latest issue of the journal Science, nearly 30 scientists led by Jerry Glover (WSU Ph.D., 2001, soil science) and Regents Professor John Reganold say perennial grains could be here in the next two decades. Such crops reestablish themselves without the aid of plowing or planting. As a result, they can be raised with less fertilizer, herbicide, fuel, and erosion than grains planted annually. The Science authors say that makes them particularly promising for farmers who work marginal land at risk of being degraded by annual grain production. Those farmers, by the way, account for half the world’s growing population.

Back in the day, as in way back at the dawn of ag, grains were perennial. But their ability to regenerate from the plant crown waned as farmers selected seeds for other traits, like yield. Perennial grains would be an elegant, ecologically sustainable way of taking farming back to the future.

You can read more here.

Meanwhile, Reganold shares this electronic conversation with Duane Schrag of the Land Institute, the renowned sustainable agriculture research group in Salina, Kansas.

Schrag: The article mentions earlier efforts at developing perennial grains. What has changed now?

Reganold: Recent advances in plant breeding have made the difference. For example, a plant breeder can characterize and exploit plant genetic variation more easily and effectively through the use of molecular marker-assisted selection. Other molecular advances and technologies, coupled with traditional breeding techniques, make the development of perennial grain crops possible in the next 20 years. This has led to the recent initiation of perennial grain programs in China, India, the United States, Australia, Argentina, and Sweden. All this said, for the great potential of perennial grain crops to be realized, more resources are needed to accelerate plant breeding programs with more personnel, land, and technological capacity.

Schrag: The article notes that while annual crop production does not pose a great risk for the best croplands, it does for marginal lands, which comprise nearly three times the area of the best croplands. What are the key reasons annual production puts marginal lands at risk, and how do perennial grains provide a solution?

Reganold: Marginal lands have poorer quality soils; that is, soils with little to no topsoil, shallow depth, poor structure, low fertility, and/or high acidity or salinity. Many marginal lands occur on steep slopes and are not suitable for annual crop cultivation year after year. They are more susceptible to soil erosion, nutrient depletion, compaction, organic matter loss, and other forms of soil degradation. Marginal lands usually require permanent soil cover to protect them from further degradation. Most annual cropping systems, with the exception for example of continuous no-till systems, don’t provide this. Compared to perennials, annuals typically grow for shorter lengths of time each year and have shallower rooting depths and lower root densities, with most of their roots restricted to the surface foot of soil or less. These traits limit their access to nutrients and water, increase their need for nutrients, and leave croplands more vulnerable to degradation.

The increased use of perennials could also slow, reverse, or prevent the increased planting of annuals on marginal lands, which now support more than half the world’s population. Developing perennial versions of our major grain crops would address many of the environmental limitations of annuals while helping to feed an increasingly hungry planet. For example, with their longer growing seasons and deeper roots, perennials can dramatically reduce water and nitrate losses. Greater soil carbon storage and reduced input requirements mean that perennials have the potential to mitigate global warming, whereas annual crops tend to exacerbate the problem. We know that perennials such as alfalfa and switchgrass are much more effective than annuals in maintaining topsoil. With perennial grains, soils are built and conserved, water is filtered, and more area is available for wildlife.

Schrag: “Farmers need more options to produce grains under different, generally less favorable circumstances …” What less favorable circumstances are anticipated?

Reganold: Less favorable circumstances include marginal lands with much less productive soils and more extreme weather conditions, such as drier or cooler climates. Perennial grains have advantages under these conditions because their longer growing seasons and more extensive root systems make them more competitive against weeds and more effective at capturing nutrients and water. Less favorable circumstances also include farmers, especially in developing countries, having less money to put towards fertilizers, pesticides, water, and fuel. In growing perennial grains, farmers won’t have to replant the crop each year, won’t have to add as much fertilizer and pesticide, and won’t have to burn as much diesel in their tractors.

Minding One’s Hrs and Zs

Work a weird shift and you can assume your sleep will be off. Angela Bowen, research assistant at the Sleep and Performance Research Center at Washington State University Spokane, calculated as much in a study presented this week at SLEEP 2010, the 24th annual meeting of the Associated Professional Sleep Societies LLC, in San Antonio.

Using mathematical modeling, Bowen compared the sleep and fatigue one might expect between typical working schedules and less desirable ones. Start work between 9 a.m. and 2 p.m., and you can expect to get eight hours of sleep in. But pull a shift between 8 p.m. and midnight, and you might be working on less than five hours of sleep.

Flickr image courtesy of Fabbio--http://www.flickr.com/photos/fabiovenni/

“In comparison to day time schedules, the night schedules had much less predicted sleep and greater fatigue on shift,” Bowen writes in an email from San Antonio—and yes, she’s having a wonderful time.

What’s surprising is that, if you’re going to take a graveyard shift, you’ll want to make it a true graveyard shift and start after midnight. It’s a timing play and it lets a worker sleep right before going to work, arriving rested.

The research has implications for so-called hours-of-service regulations, which currently aim to reduce  fatigue by limiting the hours one works in a day. Such regulations ignore the body’s circadian rhythms, says Bowen. If her modeling is validated in real or simulated work environments, she says, it can be used to recommend more sleep-friendly schedules.

The SLEEP 2010 abstract supplement is available for download on the website of the journal SLEEP at http://www.journalsleep.org/ViewAbstractSupplement.aspx.

Go here to read some of the news coverage of Bowen’s study.

More News of Life on Mars and Saturn’s Titan

For several years now, WSU astrobiologist Dirk Schulze-Makuch has been building a case for extraterrestrial life. Just this spring, he and several colleagues reported finding microbial life in an incredibly inhospitable lake of asphalt in the Caribbean, suggesting life might similarly be found in the liquid hydrocarbon environments of Saturn’s moon, Titan.

Now comes word that ancient Mars seems to have had a wet, non-acidic environment favorable to life. Researchers led by NASA’s Richard Morris and writing in the journal Science say the evidence lies in an outcrop of rock with high amounts of carbonate, which forms in wet conditions and dissolves in acid.

Carbonate-Containing Martian Rocks (color added)/Image courtesy of NASA, JPL-Caltech, and Cornell University

The finding, says Schulze-Makuch, “supports the notion of a warmer and wetter early Mars with substantial amounts of liquid water on its surface, probably in the form of oceans. Thus, early Mars was certainly a habitable planet and the origin of single-cellular life on Mars or transfer of that type of life from Earth to Mars or vice versa is certainly plausible.”

No sooner does Schulze-Makuch say this when we read of the Cassini spacecraft finding no sign of acetylene on Titan. A separate study found evidence that hydrogen is disappearing near the moon’s surface. The discoveries support a theory that Titanic microbes could survive by breathing hydrogen gas and eating acetylene, producing methane as a result.

Schulze-Makuch calls the discoveries “extremely intriguing.”

“A biological explanation would be quite plausible as hydrogen is the most basic ingredient for metabolism on Earth and acetylene is an energy-rich molecule that could be harvested as part of a methanogenic metabolism on Titan,” he says.

In fact, he predicted as much in 2005, writing with David Grinspoon in the journal Astrobiology.

“Obviously, inorganic explanations have to be eliminated as a possibility before we conclude that biology is the cause,” he says. “However, an inorganic explanation is difficult to invoke since a strong catalyst would be needed to remove the hydrogen and acetylene falling from Titan’s atmosphere under the very cold surface temperatures on Titan. Indeed, what is observed is exactly what we would expect if life on Titan is present that uses hydrogen and acetylene in its metabolic pathway and produces methane as a result.”

Very cool video of how the Spirit Mars Rover operates on rock can be seen here. You can also read a lot more about Schulze-Makuch’s thinking on extraterrestrial life in his recent and eminently readable book, We Are Not Alone.