MICROBE SURVIVES IN OCEAN'S DEEPEST REALM, THANKS TO GENETIC ADAPTATIONS

Photo: University of Delaware

Friday, 27 February 2009 00:34
The genome of a marine bacterium living 2,500 meters below the ocean's surface is providing clues to how life adapts in extreme environments, according to a paper published Feb. 6, 2009, in the journal PLoS Genetics.


The research focused on the bacterium Nautilia profundicola, a microbe that survives near deep-sea hydrothermal vents. It was found in a fleece-like lining on the backs of Pompeii worms, a type of tubeworm that lives at hydrothermal vents, and in bacterial mats on the surfaces of the vents' chimney structures.

One gene, called rgy, allows the bacterium to manufacture a protein called reverse gyrase when it encounters extremely hot fluids from the Earth's interior released from the sea floor.

"The discovery of reverse gyrase in Nautilia profundicola suggests that it plays a key role in this microbe's ability to thrive near deep-sea hydrothermal vents, where conditions are thought to resemble those found on early Earth," said Matt Kane, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research. "Knowledge of microbes living near vents may aid our understanding of how life evolved."

The study involved scientists at the University of Delaware, the University of California, the Universities of Louisville, Ky., and Waikato, New Zealand, and the J. Craig Venter Institute.

They combined genome analysis with physiological and ecological observations to investigate the importance of one gene, rgy, in N. profundicola's ability to adapt to the extreme changes it's exposed to in the deep sea.

"Previous studies found the gene only in microorganisms growing in temperatures greater than 80 degrees Celsius, but Nautilia profundicola thrives best at much lower temperatures," said Barbara Campbell, a marine scientist at the University of Delaware.

"The gene's presence in Nautilia profundicola suggests that it might play a role in the bacterium's ability to survive rapid and frequent temperature fluctuations in its environment."

Photosynthesis doesn't occur in this dark environment, where hot, toxic fluids oozing from below the seafloor combine with cold seawater at very high pressures.

Microorganisms that thrive at hydrothermal vents must adapt to fluctuations in temperature and oxygen levels, ranging from the hot, sulfide- and heavy metal-laden plume at the vents' outlets to cold seawater in the surrounding region.

The researchers uncovered further adaptations to the vent environment in Nautilia profundicola, including genes necessary for growth and for sensing environmental conditions. They also proposed a new route for bacterial nitrate assimilation related to how other bacteria use ammonia as an energy source.

Nautilia profundicola contains all the genes necessary for life in conditions widely believed to mimic those in our planet's early biosphere.

"It will be an important model system," said Campbell, "for understanding early microbial life on Earth."



The National Science Foundation

ATMOSPHERIC SUNSHADE COULD REDUCE SOLAR POWER GENERATION

Photo: Department of Energy/National Renewable Energy Laboratory

Tuesday, 24 March 2009 13:24 The concept of delaying global warming by adding particles into the upper atmosphere to cool the climate could unintentionally reduce peak electricity generated by large solar power plants by as much as one-fifth, according to a new NOAA study. The findings appear in Environmental Science and Technology.


“Injecting particles into the stratosphere could have unintended consequences for one alternative energy source expected to play a role in the transition away from fossil fuels,” said author Daniel Murphy, a scientist at NOAA’s Earth System Research Laboratory in Boulder, Colo.

The Earth is heating up as fossil-fuel burning produces carbon dioxide, the primary heat-trapping gas responsible for man-made climate change. To counteract the effect, some geoengineering proposals are designed to slow global warming by shading the Earth from sunlight.

Among the ideas being explored is injecting small particles into the upper atmosphere to produce a climate cooling similar to that of large volcanic eruptions, such as Mt. Pinatubo’s in 1991. Airborne sulfur hovering in the stratosphere cooled the Earth for about two years following that eruption.

Murphy found that particles in the stratosphere reduce the amount and change the nature of the sunlight that strikes the Earth. Though a fraction of the incoming sunlight bounces back to space (the cooling effect), a much larger amount becomes diffuse, or scattered, light.

On average, for every watt of sunlight the particles reflect away from the Earth, another three watts of direct sunlight are converted to diffuse sunlight. Large power-generating solar plants that concentrate sunlight for maximum efficiency depend solely on direct sunlight and cannot use diffuse light.

Murphy verified his calculations using long-term NOAA observations of direct and diffuse sunlight before and after the 1991 eruption.

After the eruption of Mt. Pinatubo, peak power output of Solar Electric Generating Stations in California, the largest collective of solar power plants in the world, fell by up to 20 percent, even though the stratospheric particles from the eruption reduced total sunlight that year by less than 3 percent.

“The sensitivity of concentrating solar systems to stratospheric particles may seem surprising,” said Murphy. “But because these systems use only direct sunlight, increasing stratospheric particles has a disproportionately large effect on them.”

Nine Solar Electric Generating Stations operate in California and more are running or are under construction elsewhere in the world. In sunny locations such systems, which use curved mirrors or other concentrating devices, generate electricity at a lower cost than conventional photovoltaic, or solar, cells.

Flat photovoltaic and hot water panels, commonly seen on household roofs, use both diffuse and direct sunlight. Their energy output would decline much less than that from concentrating systems.

Even low-tech measures to balance a home’s energy, such as south-facing windows for winter heat and overhangs for summer shade, would be less effective if direct sunlight is reduced.



National Oceanic and Atmospheric Administration

HIGH CO2 BOOSTS PLANT RESPIRATION, POTENTIALLY AFFECTING CLIMATE AND CROPS

Friday, 27 February 2009 00:43
The leaves of soybeans grown at the elevated carbon dioxide levels predicted for the year 2050 respire more than those grown under current atmospheric conditions, researchers report, a finding that will help fine-tune climate models and could point to increased crop yields as CO2 levels rise.

Photo: Don Hamerman
The study, from researchers at the University of Illinois and the U.S. Department of Agriculture, appears this week in the Proceedings of the National Academy of Sciences.

Plants draw CO2 from the atmosphere and make sugars through the process of photosynthesis. But they also release some CO2 during respiration as they use the sugars to generate energy for self-maintenance and growth. How elevated CO2 affects plant respiration will therefore influence future food supplies and the extent to which plants can capture CO2 from the air and store it as carbon in their tissues.

While there is broad agreement that higher atmospheric CO2 levels stimulate photosynthesis in C3 plants, such as soybeans, no such consensus exists on how rising CO2 levels will affect plant respiration.

“There’s been a great deal of controversy about how plant respiration responds to elevated CO2,” said U. of I. plant biology professor Andrew Leakey, who led the study. “Some summary studies suggest it will go down by 18 percent, some suggest it won’t change, and some suggest it will increase as much as 11 percent.”

Understanding how the respiratory pathway responds when plants are grown at elevated CO2 is key to reducing this uncertainty, Leakey said. His team used microarrays, a genomic tool that can detect changes in the activity of thousands of genes at a time, to learn which genes in the high CO2 plants were being switched on at higher or lower levels than those of the soybeans grown at current CO2 levels.

Rather than assessing plants grown in chambers in a greenhouse, as most studies have done, Leakey’s team made use of the Soybean Free Air Concentration Enrichment (Soy FACE) facility at Illinois. This open-air research lab can expose a soybean field to a variety of atmospheric CO2 levels – without isolating the plants from other environmental influences, such as rainfall, sunlight and insects.

Some of the plants were exposed to atmospheric CO2 levels of 550 parts per million (ppm), the level predicted for the year 2050 if current trends continue. These were compared with plants grown at ambient CO2 levels (380 ppm).

The results were striking. At least 90 different genes coding the majority of enzymes in the cascade of chemical reactions that govern respiration were switched on (expressed) at higher levels in the soybeans grown at high CO2 levels. This explained how the plants were able to use the increased supply of sugars from stimulated photosynthesis under high CO2 conditions to produce energy, Leakey said. The rate of respiration increased 37 percent at the elevated CO2 levels.

The enhanced respiration is likely to support greater transport of sugars from leaves to other growing parts of the plant, including the seeds, Leakey said.

“The expression of over 600 genes was altered by elevated CO2 in total, which will help us to understand how the response is regulated and also hopefully produce crops that will perform better in the future,” he said.

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Fish numbers outpace human population

http://www.newscientist.com/article/dn16692-fish-numbers-outpace-human-population.html
Fish numbers outpace human population

17:50 02 March 2009 by Debora MacKenzie
For similar stories, visit the Endangered Species and Mysteries of the Deep Sea Topic Guides



It's increasingly likely that the fish you eat was farmed not caught wild, according to the latest statistics of the UN Food and Agriculture Organization.
The group's two-yearly assessment of world fisheries, published today, comes with mitigated good news.
The outlook for wild ocean fish remains gloomy: 80% of all fisheries are at or beyond their maximum yields, and over-fishing continues to climb. Yet the amount of fish available to eat is growing faster than the human population, thanks to a boom in fish farming.
The FAO calculates that, for the first time, fish farms produce half the fish we eat, up from less than a third in 2002. With wild-catch fisheries maxed out, any more increases in fish production will depend on farms.
Problems in the wild?
It is unclear from the FAO data whether fish farms are indirectly putting more pressure on wild stocks.
Many farmed fish eat fishmeal and oil, made from small species like sardines. The FAO says the tonnage of these species consumed has trebled since 1992, but does not say whether this is a consequence of fish farming, or because the fish are being used for other purposes.
In a parallel report, international fisheries pressure group Oceana charges that by relying on wild-caught species like sardines, which now constitute one third of world fisheries, fish farms are starving larger predators, including tuna, marine mammals and seabirds.
The FAO observes that the unrestricted competition between companies is a waste of energy: too many boats mean that fewer fish are caught per litre of boat fuel. Meanwhile, boat owners buy more powerful, less efficient engines to beat the competition.