Archeobatteri metanogeni, prima che ci fosse ossigeno.

Discovery opens up new areas of microbiology, evolutionary biology

  An international team of researchers led by scientists at Virginia Tech and the University of California, Berkeley has discovered that a process that turns on photosynthesis in plants likely developed on Earth in ancient microbes 2.5 billion years ago, long before oxygen became available. 

Scientists studying methane-producing microbes, like the ones found in deep-sea hydrothermal vents, discovered that a protein critical to photosynthesis likely developed on Earth long before oxygen became available [Credit: Virginia Tech] 

The research offers new perspective on evolutionary biology, microbiology, and the production of natural gas, and may shed light on climate change, agriculture, and human health. "By looking at this one mechanism that was not previously studied, we will be able to develop new basic information that potentially has broad impact on contemporary issues ranging from climate change to obesity," said Biswarup Mukhopadhyay, an associate professor of biochemistry at the Virginia Tech College of Agriculture and Life Sciences, and the senior author of the study. 
He is also a faculty member at the Virginia Bioinformatics Institute. Plant and microbial biology professor emeritus Bob B. Buchanan co-led the research and co-authored the paper. The findings were described this week in the Proceedings of the National Academy of Sciences. This research concerns methane-forming archaea, a group of microbes known as methanogens, which live in areas where oxygen is absent. 
Methane is the main component of natural gas and a potent greenhouse gas. "This innovative work demonstrates the importance of a new global regulatory system in methanogens," said William Whitman, a professor of microbiology at the University of Georgia who is familiar with the study, but not connected to it. "Understanding this system will provide the tools to use these economically important microorganisms better." Methanogens play a key role in carbon cycling. 
When plants die, some of their biomass is trapped in areas that are devoid of oxygen, such as the bottom of lakes. Methanogens help convert the residual biological material to methane, which other organisms convert to carbon dioxide -- a product that can be used by plants. 
This natural process for producing methane forms the basis for treating municipal and industrial wastes, helps reduce pollution, and provides methane for fuel. The same process allows natural gas production from agricultural residues, a renewable resource. 
Methanogens also play an important role in agriculture and human health. 
They live in the digestive systems of cattle and sheep where they facilitate the digestion of feed consumed in the diet. Efforts to control methanogens in specific ways may improve feed utilization and enhance the production of meat and milk, researchers say. Methanogens are additionally a factor in human nutrition. The organisms live in the large intestine, where they enhance the breakdown of food. Some have proposed that restricting this activity of methanogens could help alleviate obesity. The team investigated an ancient type of methanogen, Methanocaldococcus jannaschii, which lives in deep-sea hydrothermal vents or volcanoes where environmental conditions mimic those that existed on the early Earth. 
They found that the protein thioredoxin, which plays a major role in contemporary photosynthesis, could repair many of the organism's proteins damaged by oxygen. Since methanogens developed before oxygen appeared on earth, the evidence raises the possibility that thioredoxin-based metabolic regulation could have come into play for managing anaerobic life long before the advent of oxygen. "It is rewarding to see that our decades of research on thioredoxin and photosynthesis are contributing to understanding the ancient process of methane formation," Buchanan said. "It is an excellent illustration of how a process that proved successful early in evolution has been retained in the development of highly complex forms of life."


 Source:  Virginia Tech (Virginia Polytechnic Institute and State University) [February 07, 2014]

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BARRIERA CORALLINA della GROENLANDIA

Coral reef discovered off Greenland 



By sheer coincidence, Canadian researchers have discovered a reef of living cold-water corals in southern Greenland. PhD student Helle Jørgensbye from DTU in Denmark has been investigating the reef further 

Coral from the newly discovered reef off Greenland [Credit: Bedford Institute of Oceanography] 

The first ever Greenlandic reef is located in southwest Greenland and was formed by cold-water corals with hard limestone skeletons. There are several species of coral in Greenland, but this is the first time that an actual reef has been found. In the tropics, reefs are popular tourist destination for divers, but there is little prospect of Greenland becoming a similar diving hotspot. The newly discovered living reef is located off Cape Desolation south of Ivittuut, and lies at a depth of 900 metres in a spot with very strong currents, making it difficult to reach. This also means that so far little is known about the reef itself and what lives on it The reef was discovered by accident when a Canadian research vessel needed to take some water samples. When the ship sent the measuring instruments down to a depth of 900 metres, they came back up completely smashed. Fortunately there were several pieces of broken coral branches on the instrument that showed what was responsible. "At first the researchers were swearing and cursing at the smashed equipment and were just about to throw the pieces of coral back into the sea, when luckily they realized what they were holding," says PhD student Helle Jørgensbye, DTU Aqua, who does research into life at the bottom of the west Greenland waters. The first photos Another Canadian research vessel returned to the site last fall to try and lower a camera down onto the reef to explore it close up. The coral reef is on the continental shelf itself where it is very steep and where there are strong currents. "We got some photos eventually, although we almost lost them at the bottom of the ocean as the camera got stuck fast somewhere down in the depths. Luckily we managed to get it loose again and back up to the surface," says Helle Jørgensbye. "It's been known for many years that coral reefs have existed in Norway and Iceland and there is a lot of research on the Norwegian reefs, but not a great deal is known about Greenland. In Norway, the reefs grow up to 30 metres high and several kilometres long. The great Norwegian reefs are over 8,000 years old, which means that they probably started to grow after the ice disappeared after the last ice age. The Greenlandic reef is probably smaller, and we still don't know how old it is," says Helle Jørgensbye, expressing the hope that at some point this will be investigated more closely. According to Helle Jørgensbye, finding a coral reef in southern Greenland was not entirely unexpected: "There are coral reefs in the countries around Greenland and the effect of the Gulf Stream, which reaches the west coast, means that the sea temperature get up to about 4 degrees, which is warm enough for corals to thrive. In addition to the, for Greenland, comparatively warm temperature, a coral reef also needs strong currents. Both these conditions can be found in southern Greenland," she says. Coral reefs are important areas for fish because it provides masses of food and lots of hiding places for fish fry. The Greenlandic reef is formed from Lophelia stoney corals. Other species of coral are also found in many parts of the west coast. However, they are all 'stand-alone' corals and do not form reefs. The identification of the Lophelia specimen was carried out by Professor Ole Tendal from Denmark's Natural History Museum. 
Cold Water Corals 
Normally, coral reefs are associated with the tropics, but they are also found in cold waters. While the tropical coral reefs depend on light to survive, cold-water coral reefs live in total darkness, at depths the sun's rays never penetrate. Nevertheless, they have many colourful residents and many different kinds of organisms living in them. Coral reefs are built up of thousands of small coral animals that live in a large colony which forms a common limestone skeleton. While hot water corals obtain some of the energy they need to grow from the light-dependent green algae which live in the corals, cold water coral get all their nourishment from small animals, which they catch. Thus, they are not dependent on light and can live in very deep water 

Source: Technical University of Denmark (DTU) [January 28, 2014]

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PALEOCLIMATOLOGIA

Paleoclimatology – revisiting a tiny prehistoric witness

New insights into the growth dynamics of minuscule marine organisms could help put the study of Earth’s climate, both present and prehistoric, on a more solid footing.

Foraminifera [Credit: Web]

For hundreds of millions of years, the tiny shells of single-celled marine organisms called foraminifera have been accumulating on the ocean floor. Their shells contain clues about the composition of the seawater they lived in. In a recent cooperation between EPFL and the Alfred Wegener Institute, researchers lay out a new explanation for how these organisms take up the elements they use to grow their shells, offering climatologists a better understanding into a common tool to study the Earth’s climate history. Their results were published in the journal Biogeosciences in late October, andhighlighted in the November 22 issue of Science.

Scientists often rely on secondary evidence, from ice or sediment cores, to reconstruct the prehistoric climate. Studying sediment cores containing foraminifera, scientists have reconstructed temperature timelines and analyzed the planet’s ice cover based on the composition of the shells. But as coauthor Anders Meibom explains, because they are the result of complex biological processes, foraminifer from sediment cores cannot be interpreted easily using data from inorganically formed minerals.

Not just passive transport

Foraminifera build their shells by using calcium, carbon, and oxygen that they find in seawater. Until now, scientists thought that the microorganisms used tiny “carrier bubbles,” or vacuoles, to transport seawater into them. There, calcium carbonate would precipitate from the water, forming the shell.

Scientists have long been baffled by the low magnesium concentrations in the shells. Seawater has five times more magnesium than calcium, so if minerals only entered the shells through vacuoles, they would contain large amounts of magnesium – unless it was somehow removed from the organism. Researchers have proposed a number of ways that the magnesium could be removed; yet none of them have ever been proven.

Molecular pumps that select for calcium

Instead of being taken up in vacuoles, the authors of this recent paper hold that most of the calcium is let in through transmembrane transport, which selects for calcium, but block magnesium. The fact that the shells nevertheless contain small amounts of magnesium means that both mechanisms could act in tandem, with non-selective vacuole transport accounting for the traces of magnesium found in the shells.

Based on the magnesium-calcium ratio in the surrounding seawater, the researchers developed a model to predict the magnesium-calcium ratio in the foraminifera shells. “We tested our predictions against three different experiments where foraminifera were grown in an aquarium, and the fit was almost perfect,” says Anders Meibom. According to lead author Gernot Nehrke from the Alfred Wegener Institute, their model is the first to predict the composition of the foraminifera shells without having to resort to unconfirmed theories of magnesium removal.

Beyond ice fields

“Foraminifera can provide all sorts of information on the climate, but until now, they have been treated as a black box. With this research we are beginning to understand, at a sub-cellular level, how these organisms develop, giving us a better idea about both the accuracy and the limits of sediment core measurements to reconstruct the climate of the past,” says Meibom.

Source: Ecole Polytechnique Federale de Lausanne [November 25, 2013]