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Bacterial growth could reveal Earth’s origins

May 18, 2010 By vani Leave a Comment

Washington, May 18 (ANI): For years, geologists have analyzed modern microbial mats to decipher how cells functioned as far back as 3 billion years.

Now, researchers have found a way to garner new information from cells by linking the even spacing between the thousands of tiny cones that dot the surfaces of stromatolite-forming microbial mats.

Nutrient-exchanging bacteria grow mostly on moist surfaces and collect dirt and minerals that crystallize over time.

Stromatolites are the bacteria that turn to stone just beneath the crystallized material, thereby recording their history within the crystalline skeletons.

They are considered to be the oldest fossils on Earth with patterns that also appear in cross-sectional slices of stromatolites that are 2.8 billion years old — to photosynthesis.

Scientists at MIT”s Department of Earth, Atmospheric and Planetary Sciences (EAPS) and the Russian Academy of Sciences suggest that the characteristic centimeter-scale spacing between neighboring cones that appears on modern microbial mats and the conical stromatolites they form occurs as a result of the daily competition for nutrients between neighboring mats.

By analyzing the length of the triangular patterns seen in an ancient stromatolite, for example, geologists can now infer more details about the environment in which the microbial mat lived, such as whether it lived in still or turbulent water.

The scientists proposed that the pattern was not coincidental and could pertain to a biophysical process, such as how the bacteria compete for nutrients.

By studying photosynthesis, they formed a better understanding of how a mat consumes nutrients from its surroundings over the course of a day, and then metabolizes, or breaks down, those nutrients for energy.

It takes in nutrients like inorganic carbon from its immediate surroundings and uses energy from sunlight to build sugars and new bacteria.

As these nutrients become locally depleted, the mat starts to consume nutrients from larger distances.

At nighttime when it is dark and photosynthesis is not possible, nutrients return to the water immediately surrounding the mat.

The researchers reasoned that in order to avoid direct competition for nutrients, the spacing between mats must be influenced by diffusion, or how molecules spread out over time.

In this case, diffusion is itself influenced by the amount of time a mat is metabolically active, which varies over the course of a day due to changes in sunlight. Therefore, the spacing between cones records the maximum distance that mats can compete with one another to metabolize nutrients that are spread by diffusion and later replenished at night.

After testing this theory on cultures in the lab, the researchers confirmed their hypothesis through fieldwork in Yellowstone, where the centimeter spacing between mats corresponds to their metabolic period of about 20 hours.

That the spacing pattern corresponds to the mats” metabolic period — and is also seen in ancient rocks — shows that the same basic physical processes of diffusion and competition seen today were happening billions of years ago, long before complex life appeared.

The study has been published in the Proceedings of the National Academy of Science. (ANI)

Filed Under: International News Tagged With: bacteria, Bacterial Growth, Centimeter Scale, Cones, Course Of A Day, Eaps, fossils, geologists, Inorganic Carbon, Microbial Mat, Microbial Mats, Moist Surfaces, nutrients, photosynthesis, Planetary Sciences, Russian Academy Of Sciences, skeletons, Stromatolite, Stromatolites, Turbulent Water

Cell division in bacteria just like clockwork

March 19, 2010 By vani Leave a Comment

Washington, March 19 (ANI): A new American study has found that cell division in cyanobacteria is controlled by same kind of circadian rhythms that govern human sleep.

The research conducted by scientists at MIT and the University of California at San Diego has appeared in the March 18 online edition of Science.

Previous research has demonstrated that although cyanobacteria do not “sleep” in the same way as humans, they cycle through active and resting periods on a 24-hour schedule. Cyanobacteria depend on sunlight for photosynthesis, so they are most active during the day.

The researchers showed, for the first time, how the circadian clock regulates the bacteria”s rate of cell division – their method of reproduction – in single cells.

Lead author Bernardo Pando, an MIT graduate student in physics, said: “These cells have to keep dividing, and the circadian oscillator regulates when they divide.”

In multicellular animals, including humans, cell division is crucial for renewal and repair, while out-of-control cell division causes cancer, so “understanding how cells are dividing is really of fundamental importance,” says Susan Golden, professor of molecular biology at the University of California at San Diego and an author of the paper.

Cyanobacteria maintain their circadian rhythms even when isolated from the naturally occurring daily light-dark cycles of the sun, just like humans. The scientists discovered that under conditions of moderate constant light, the cyanobacteria undergo cell division about once per day, and the divisions take place mostly at the midpoint of the 24-hour cycle.

To find how the cell division cycle is coupled to the circadian clock, the researchers sped up the cell cycle by boosting the intensity of light, enabling the cells to photosynthesize more, which increases the amount of energy available to them. The cells did start to divide more frequently, but in a pattern still linked to the circadian clock — they divided once a quarter of the way into the cycle, and again three-quarters into the cycle.

The research group also showed that the cyanobacteria enter a resting phase about 19 hours into the circadian cycle, after which they will not divide until the next cycle begins.

For the study, the researchers tracked single cells over a weeklong period. Proteins that govern the circadian clock were tagged with yellow fluorescent protein, so each cell”s position in the 24-hour cycle could be pinpointed. Photographs of the cells were taken every 40 minutes, so researchers could see when they divided.

This is the first time researchers have studied how cell cycle and circadian rhythms are coupled in individual bacterial cells.

Alexander van Oudenaarden, MIT professor of biophysics and senior author of the paper, said: “You can only do this by looking at single cells.”
(ANI)

Filed Under: International News Tagged With: bacteria, cells, Circadian Clock, circadian rhythms, cyanobacteria, Fundamental Importance, graduate student, Intensity Of Light, march 19, midpoint, molecular biology, Multicellular Animals, oscillator, Pando, photosynthesis, previous research, Scientists, sunlight, University of California, university of california at san diego

How plants prevent their genes from going haywire

September 12, 2009 By admin Leave a Comment

Washington, September 11 (ANI): A new study, by researchers at the Universite de Montreal in Canada, has found a key mechanism that enables plants to keep dangerous gene alterations in check to ensure their continued existence.

“We’ve discovered a new pathway that plants use to protect their genes against dangerous alterations that could also allow some useful mutations to occur,” said Normand Brisson, a Universite de Montreal biochemistry professor who made his discovery with graduate students Alexandre Marechal and Jean-Sebastien Parent.

“Such mutations played an important role in the evolution of plants with high nutritional value, resistance to disease and harsh climate that are so important to modern agriculture,” added Dr. Brisson.

“Our results open new research avenues for the study of similar mechanisms of gene repair in humans that might be important for human evolution, our responses to stress and the prevention of devastating diseases,” he said.

All living things are constantly exposed to stressors that can provoke gene mutations, yet if uncorrected such mutations can have disastrous consequences such as the development of cancers in humans or cell resistance to cancer-fighting drugs.

Cells have evolved a battery of mechanisms to correct mutations, including recently discovered strategies that can also modify the number of copies of individual genes.

These corrective mechanisms have attracted a lot of scientific interest since they could play a key role in species evolution.

Dr Brisson suspected that a protein family he has studied for years, called the “Whirlies” might be important to protect against mutations in plant cells – specifically in the chloroplast – the engine of photosynthesis that allows plants to transform carbon dioxide into sugar and expel the oxygen we breathe.

Working with his students and Biochemistry Professor Franz Lang, they showed that Whirlies are key to preventing major rearrangements of genes that could result in the creation of multiple gene copies.

The discovery is important, since the number of copies of a gene must be kept scrupulously in balance with other genes so they can function correctly together.

Even though gene multiplication can be thought of as detrimental, such multiplication can be an important adaptation to stressors and so keeping such mutations in check must be balanced against creating mutations that may actually help living things survive in changing conditions. (ANI)

Filed Under: Uncategorized Tagged With: alexandre marechal, biochemistry professor, carbon dioxide, chloroplast, Disastrous Consequences, Evolution Of Plants, gene alterations, Gene Mutations, gene repair, Harsh Climate, human evolution, jean sebastien, key role, Nutritional Value, photosynthesis, plant cells, Protein Family, research avenues, species evolution, stressors, universite de montreal

Photosynthetic viruses keep world’s oxygen levels up

September 1, 2009 By admin Leave a Comment

London, August 31 (ANI): A new research has shown that photosynthetic viruses can keep the world’s oxygen levels up.

The viruses, which infect single-celled algae called cyanobacteria, are hyper efficient photosynthesisers thanks to a unique set of genes.

Previous work had shown that cyanophage viruses have some photosynthesis genes, apparently used to keep the host cyanobacteria on life support during the infection, which otherwise knocks out the cells’ basic functions.

Now, according to a report in New Scientist, Oded Beja from the Technion-Israel Institute of Technology in Haifa said that the cyanophages’ photosynthetic proficiency doesn’t stop there.

While screening DNA sequences in water samples collected during Craig Venter’s Global Ocean Sampling Expedition, his team discovered seven more photosynthesis genes coding for a complex of proteins collectively named photosystem I.

They believe the viral complex has a unique shape that makes cyanophage photosynthesis hyperefficient.

In normal photosynthesis, photosystem I grabs electrons from proteins higher up in the photosynthesis chain reaction.

According to the team, the viral photosystem I genes allow the cyanophages to not only take electrons from the proteins involved in photosythesis but also from other algal proteins.

“We suspect that when these phages enter the cell, they start to replace (the cell’s) photosystem,” said Beja.

“By grabbing electrons from all sources available at the time, they get more energy out of photosynthesis,” he added.

Eric Wommack of the University of Delaware in Newark said that the discovery suggests these viruses may play a role in global oxygen production.

“Their hosts produce half the world’s oxygen and roughly 10 per cent of these cells are infected by cyanophages,” he said.

“So it is possible that as much as 5 per cent of the world’s oxygen production results from cyanophage infected cells,” he added. (ANI)

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Marine viruses may contribute to ocean energy

August 30, 2009 By admin Leave a Comment

Washington, August 30 (ANI): A new study has determined that marine viruses which have borrowed a key set of bacterial photosynthetic genes may be contributing more to the oceans’ energy production than previously thought.

Researchers at the Technion-Israel Institute of Technology carried out the study.

Technion professor Oded Beja and colleagues suggest that the viruses, or marine phages, may use the genes to gain a competitive advantage over the bacteria they infect and other viruses.

But, the findings, along with earlier reports of phages with photosynthetic genes, could “change our calculations of how energy is generated in the oceans,” said Beja.

“About 40 percent of photosynthesis on Earth is done in the oceans, and 50 percent of that is done by cyanobacteria. Now we have to ask how much of this is done with viruses,” he added.

The transfer of genes from bacteria to viruses is a common mode of evolution among microbes, “like a baton being passed between runners,” said Dr. Paul Falkowski, a professor of marine, earth and planetary sciences at Rutgers University.

“Future analyses of the massive sets of genetic data gleaned from marine environments will certainly turn up other genes-beyond those associated with photosynthesis-that have made the leap from microbe to virus,” he said.

The genes were found in marine viruses or phages that infect Prochlorococcus and Synechococcus cyanobacteria, the tiny, blue-green and single-celled ocean dwellers that are among the most numerous photosynthetic cells in the seas.

The viruses may have incorporated the genes as a way to gain more energy as they infect and reproduce, although the research team hasn’t confirmed whether the genes really do give the viruses an energetic edge.

The bacteria genes co-opted by the marine viruses are part of a group, or “cassette” of genes called photosystem I.

Photosystem I and another gene cassette called photosystem II genes are essential to the first steps of photosynthesis, absorbing energy from light and transforming into a form that can be used to fuel further reactions in the process.

It was a laboratory bet between Beja and Ph.D. students Itai Sharon and Ariella Alperovitch that led to the discovery of the photosystem I cassette in viruses.

After scouring genome databases from a selection of marine bacteria and viruses, the students won the bet and found the bacterial photosystem I genes integrated in the viral genome.

Clues as to why the photosystem I genes are valuable to the viruses may come from the crystal structure modeling of the photosystem I protein complex from the viruses.

The complex’s structure may help the viral complex expand its sources of energy beyond those available to the bacterial complex.

“Such an energy boost could be vital to a virus’s fitness,” Beja suggested. (ANI)

Filed Under: Science News Tagged With: beja, competitive advantage, cyanobacteria, dr paul, energy production, first steps, genetic data, israel institute, Marine Environments, marine viruses, massive sets, microbe, microbes, Ocean Energy, phages, photosynthesis, photosynthetic cells, photosynthetic genes, Planetary Sciences, rutgers university, steps of photosynthesis, Technion Israel Institute Of Technology

Fusing of ancient microbes reveals new pathway for evolution of life on Earth

August 20, 2009 By admin Leave a Comment

Washington, August 20 (ANI): NASA-funded research has found that humans not might be walking on Earth today if not for the ancient fusing of two microscopic, single-celled organisms called prokaryotes 2.5 billion years ago, which reveals a new pathway for the evolution of life on Earth.

By comparing proteins present in more than 3000 different prokaryotes – a type of single-celled organism without a nucleus – molecular biologist James A. Lake from the University of California at Los Angeles’ Center for Astrobiology showed that two major classes of relatively simple microbes fused together more than 2.5 billion years ago.

This endosymbiosis, or merging of two cells, enabled the evolution of a highly stable and successful organism with the capacity to use energy from sunlight via photosynthesis.

Further evolution led to photosynthetic organisms producing oxygen as a byproduct.

The resulting oxygenation of Earth’s atmosphere profoundly affected the evolution of life, leading to more complex organisms that consumed oxygen, which were the ancestors of modern oxygen-breathing creatures including humans.

“Higher life would not have happened without this event,” Lake said. “These are very important organisms. At the time these two early prokaryotes were evolving, there was no oxygen in the Earth’s atmosphere. Humans could not live. No oxygen-breathing organisms could live,” he added.

The genetic machinery and structural organization of these two organisms merged to produce a new class of prokaryotes, called double membrane prokaryotes.

As they evolved, members of this double membrane class, called cyanobacteria, became the primary oxygen-producers on the planet, generating enough oxygen to alter the chemical composition of the atmosphere and set the stage for the evolution of more complex organisms such as animals and plants.

According to Carl Pilcher, director of the NASA Astrobiology Institute at NASA’s Ames Research Center in Moffett Field, California, “This work is a major advance in our understanding of how a group of organisms came to be that learned to harness the sun and then effected the greatest environmental change Earth has ever seen, in this case with beneficial results.” (ANI)

Filed Under: Science News Tagged With: Ames Research, ames research center, Ancient Microbes, animals and plants, byproduct, Carl Pilcher, chemical composition, composition of the atmosphere, double membrane, endosymbiosis, Evolution Of Life, evolution of life on earth, genetic machinery, life on earth, moffett field california, molecular biologist, Nasa Astrobiology Institute, oxygenation, photosynthesis, Single Celled Organism, single celled organisms, structural organization, University Of California At Los Angeles

Ice-free summers in ancient Arctic may help predict future trends

July 10, 2009 By admin Leave a Comment

Washington, July 10 (ANI): In a new research, scientists have obtained evidence for ice-free summers with intermittent winter sea ice in the Arctic Ocean during the Late Cretaceous period, which should help predict how the Arctic is likely to respond to future global warming.

The Late Cretaceous, the period between 100 and 65 million years ago leading up to the extinction of the dinosaurs, is crucial in this regard because levels of carbon dioxide (CO2) were high, driving greenhouse conditions.

In this regards, Dr Andrew Davies and Professor Alan Kemp of the University of Southampton’s School of Ocean and Earth Science based at the National Oceanography Centre, Southampton, along with Dr Jennifer Pike of Cardiff University have presented the first seasonally resolved Cretaceous sedimentary record from the Alpha Ridge of the Arctic Ocean.

The scientists analyzed the remains of diatoms – tiny free-floating plant-like organisms – preserved in late Cretaceous marine sediments.

In modern oceans, diatoms play a dominant role in the ‘biological carbon pump’ by which CO2 is drawn down from the atmosphere through photosynthesis and a proportion of it exported to the deep ocean.

Unfortunately, the role of diatoms in the Cretaceous oceans has until now been unclear, in part because they are often poorly preserved in sediments.

But, the researchers struck lucky.

“With remarkable serendipity, successive US and Canadian expeditions that occupied floating ice islands above the Alpha Ridge of the Arctic Ocean, recovered cores containing shallow buried upper Cretaceous diatom ooze with superbly preserved diatoms,” explained the researchers.

This has allowed them to conduct a detailed study of the diatom fossils using sophisticated electron microscopy techniques.

In the modern ocean, scientists use floating sediment traps to collect and study settling material.

These electron microscope techniques that have been pioneered by Professor Kemp’s group at Southampton have unlocked a ‘palaeo-sediment trap’ to reveal information about Late Cretaceous environmental conditions.

They find that the most informative sediment core samples display a regular alternation of microscopically thin layers composed of two distinctly different diatom assemblages, reflecting seasonal changes.

Their analysis clearly demonstrates that seasonal blooming of diatoms was not related to the upwelling of nutrients, as has been previously suggested.

Rather, production occurred within a stratified water column, indicative of ice-free summers.

According to the researchers, “This Cretaceous production, dominated by diatoms adapted to stratified conditions of the polar summer may also be a pointer to future trends in the modern ocean.”

“With increasing CO2 levels and global warming giving rise to increased ocean stratification, this style of (marine biological) production may become of increasing importance,” they added. (ANI)

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Plants’ internal clocks may improve climate change scenarios

July 3, 2009 By admin Leave a Comment

Washington, July 3 (ANI): In a new study, scientists have suggested that the internal clock in plants can help make climate change scenarios and CO2 level figures more accurate.

The study was done by an international team of researchers led by the University of Castilla-La-Mancha (UCLM) in Spain.

The team compiled the research carried out to date on this topic in order to understand the implications of the so-called “circadian clock” as regards the survival and ecology of a wide range of plant species.

The plants of the model species Arabidopsis thaliana, created in a laboratory environment without this ability, found it difficult to survive and reproduced less frequently.

“One hour before the sun comes out, a plant with a circadian clock already knows that it is time to wake up and all the genes associated to photosynthesis begin to activate,” said Víctor Resco de Dios, main author of the study and a researcher in the Environmental Science Department of the UCLM.

The study, which has been published in the latest issue of Ecology Letters, reveals the ecological implications of plants’ ability to “tell the time”.

Researchers have studied the genes involved in photosynthesis and adapting to the climate.

As much as 90 percent of a plant’s genes are regulated by the circadian clock.

“The clock coordinates when a plant should flower and also when it should germinate a seed,” said Resco de Dios.

According to the scientist, the circadian clock has a great capacity to adapt to its physical environment.

Plants take up CO2 by means of photosynthesis and can potentially mitigate climate change.

However, “in studies performed by ecologists to ascertain the level of CO2 in the models, circadian regulation was not taken into account,” said Resco de Dios.

The team of scientists suggests this regulation should be included in climate models based on the study of plant life in order to obtain better and more accurate results.

“A normal climate change model would forecast photosynthesis to be uniform between 6am and 10am in a tropical forest if environmental conditions (light, humidity, temperature, etc) are constant. However, as plants have a circadian clock, photosynthesis is seen to increase during that time of the day,” said Resco de Dios.

According to the scientists, the circadian clock may well be the key for plants to survive a rise in temperatures.

Plants without optimised circadian regulation will have “more difficulty to adjust to climate changes and survive the stress”. (ANI)

Filed Under: Science News Tagged With: accurate results, castilla la mancha, change model, Circadian Clock, Climate Change Scenarios, Climate Models, ecological implications, ecologists, ecology letters, environmental science department, genes, Internal Clock, Internal Clocks, laboratory environment, model species, photosynthesis, Physical Environment, plant species, resco, time researchers, uclm

Tooth evidence shows dinos once lived in the Arctic

April 27, 2009 By admin Leave a Comment

Washington, April 27 (ANI): Scientists have discovered a dinosaur tooth along what’s now the Kakanaut River of northeastern Russia, a find that shows dinos once lived above the Arctic Circle.

Scientists say the dinosaurs became extinct 65 million years ago when a big meteor crash set off volcanoes galore, with dust and smoke filling up the air.

One theory holds that cold, brought on by the Sun’s concealment, is what did them in, but a team of paleontologists led by Pascal Godefroit, of the Royal Belgian Institute of Natural Sciences in Brussels, argues otherwise.

According to them, some dinosaurs (warm-blooded, perhaps) were surprisingly good at withstanding near-freezing temperatures.

The team’s latest find, a diverse stash of dinosaur fossils laid down just a few million years before the big impact, along what’s now the Kakanaut River of northeastern Russia, is proof of their theory.

Even accounting for continental drift, the dinos lived at more than 70 degrees of latitude north, well above the Arctic Circle.

The scientists also say that the dinosaurs above the Arctic weren’t lost wanderers.

The fossils include dinosaur eggshells – a first at high latitudes, and evidence of a settled, breeding population.

But, life was not easy for the dinosaurs during that period.

The size and shape of fossilized leaves found with the bones enabled Godefroit’s team to estimate a mean annual temperature of 50 degrees Fahrenheit, with wintertime lows at freezing.

According to the team of scientists, all that dust in the atmosphere must have curtailed photosynthesis everywhere, weakening the base of the food chain and inflicting starvation, and finally extinction, upon the dinosaurs. (ANI)

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Scientists discover microbes that survive without oxygen under Antarctic glacier

April 17, 2009 By admin Leave a Comment

Washington, April 17 (ANI): A new research has led to the discovery of unusual microbial life under an inland Antarctic glacier, a place where cold, darkness and lack of oxygen would previously have led scientists to believe nothing could survive.

The microbes were found in an unmapped reservoir of briny liquid chemically similar to sea water, but buried under an inland Antarctic glacier.

After sampling and analyzing the outflow from below the Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet in the otherwise ice-free McMurdo Dry Valleys of Antarctica, researchers believe that, lacking enough light to make food through photosynthesis, the microbes have adapted over the past 1.5 million years to manipulate sulfur and iron compounds to survive.

The microbes also are remarkably similar in nature to species found in marine environments, leading to the conclusion that the populations under the glacier are the remnants of a larger population of microbes that once occupied a fjord or sea that received sunlight.

Many of these marine lineages likely declined, while others adapted to the changing conditions when the Taylor Glacier advanced, sealing off the system under a thick ice cap.

The Dry Valleys are completely devoid of animals and complex plants and scientists consider them to be one of the Earth’s most extreme deserts.

Mikucki and her colleagues based their analysis on samples taken at the ominously, but aptly named Blood Falls, a water-fall-like feature at the edge of the glacier that flows irregularly, but often has a strikingly bright red appearance in stark contrast to the icy background.

Mikucki and her colleagues argue that the creatures that survive under the Taylor Glacier are both far more exotic and far more adaptable than the early explorers thought.

Because the outflow from the glacier follows no clear pattern, it took a number of years to obtain the samples needed to conduct an analysis.

Finally, she obtained a sample of an extremely salty and clear liquid for analysis.

“When I started running the chemical analysis on it, there was no oxygen,” she said. “That was this when got really interesting, it was a real ‘eureka’ moment,” she added.

Further genetic analysis suggests that of the relatively small numbers of microorganisms found in the brine, “the majority of these organisms are from marine lineages,” she said.

In other words, microorganisms more similar to those found in an ocean than on land, but capable of surviving without the food and light sources available in the open ocean. (ANI)

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A large size and a fast bite made some fish go extinct 65 million years ago

March 29, 2009 By admin Leave a Comment

Washington, March 27 (ANI): A new study has unraveled why certain fishes went extinct 65 million years ago, attributing the reason of their decline to a large size and a fast bite.

Today, those same features characterize large predatory bony fishes, such as tuna and billfishes, that are currently in decline and at risk of extinction themselves, according to Matt Friedman, author of the study and a graduate student in evolutionary biology at the University of Chicago.

“The same thing is happening today to ecologically similar fishes,” he said. “The hardest hit species are consistently big predators,” he added.

Studies of modern fishes demonstrate that large body size is linked to large prey size and low rates of population growth, while fast-closing jaws appear to be adaptations for capturing agile, evasive prey-in other words, other fishes.

The fossil record provides some remarkable evidence supporting these estimates of function: fossil fishes with preserved stomach contents that record their last meals.

When an asteroid struck the earth at the end of the Cretaceous about 65 million years ago, the resultant impact clouded the earth in soot and smoke.

This blocked photosynthesis on land and in the sea, undermined food chains at a rudimentary level, and led to the extinction of thousands of species of flora and fauna, including dinosaurs.

Scientists had speculated that during that interval large predatory fishes might have been more likely than other fishes to go extinct because they tended to have slowly increasing populations, live more spread out, take longer to mature, and occupy precarious positions at the tops of food chains.

Today, ecologically similar fishes appear to be the least able to rebound from declining numbers due to overfishing.

To build the database he needed to test this prediction, Friedman traveled around the world measuring the body size and jaw bones of 249 genera of fossil fishes that lived during the late Cretaceous.

These kinds of direct measurements are possible in fossil fishes because many are represented by complete, articulated individuals.

This is unlike the fossil record of most other vertebrates, where bones, teeth and other parts of the skeleton are often scattered and found in isolation.

This study is the first to test this theory with hard data and to quantify the relationship between body size, jaw function and vulnerability of fishes during the Cretaceous extinction, according to Friedman.

“Anyway you sliced it, the data showed that if you were a big fish with a fast bite you were toast,” he said. (ANI)

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Scientists discover new possibilities for hydrogen-producing algae

March 25, 2009 By admin Leave a Comment

Washington, March 25 (ANI): Researchers studying a hydrogen-producing, single-celled green alga, Chlamydomonas reinhardtii, have unmasked a previously unknown fermentation pathway that may open up possibilities for increasing hydrogen production.

C. reinhartii, a common inhabitant of soils, naturally produces small quantities of hydrogen when deprived of oxygen. Like yeast and other microbes, under anaerobic conditions this alga generates its energy from fermentation.

During fermentation, hydrogen is released though the action of an enzyme called hydrogenase, powered by electrons generated by either the breakdown of organic compounds or the splitting of water by photosynthesis.

Normally, only a small fraction of the electrons go into generating hydrogen.

However, a major research goal has been to develop ways to increase this fraction, which would raise the potential yield of hydrogen.

In the new study, researchers at the Carnegie Institution’s Department of Plant Biology, the National Renewable Energy Laboratory (NREL), and the Colorado School of Mines (CSM), examined metabolic processes in a mutant strain that was unable to assemble an active hydrogenase enzyme.

The researchers expected the cell’s metabolism to compensate by increasing metabolite flow along other known fermentation pathways, such as those producing formate and ethanol as end products.

Instead, the algae activated a pathway leading to the production of succinate, which was previously not associated with fermentation metabolism in C. reinhardtii.

Notably, succinate, a widely used industrial chemical normally synthesized from petroleum, is included in the Department of Energy’s list of the top 12 value added chemicals from biomass.

“We actually didn’t know that this particular pathway for fermentation metabolism existed in the alga until we generated the mutant,” said Carnegie’s Arthur Grossman.

“This finding suggests that there is significant flexibility in the ways that soil-dwelling green algae can metabolize carbon under anaerobic conditions,” he added.

“By blocking and modifying some of these metabolic pathways, we may be able to augment the donation of electrons to hydrogenase under anaerobic conditions and produce elevated levels of hydrogen,” he further added.

Grossman led the effort to generate a fully sequenced Chlamydomonas genome, which has allowed researchers to identify key genes encoding proteins involved in both fermentation and hydrogen production.

Grossman feels that it is of immediate importance to generate new mutant strains to help us understand how we may be able to alter fermentation metabolism and the production of hydrogen. (ANI)

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Oceans were filled with oxygen 700 million years earlier than believed

March 17, 2009 By admin Leave a Comment

Sydney, March 17 (ANI): An international team of geologists has claimed that photosynthesizing life forms created an excess of oxygen in the oceans 700 million years earlier than previous estimates suggest.

According to a report in ABC News, bands of haematite in the Marble Bar Cherst reveal the presence of aerobic bacteria nearly 3.5 billion years ago.

The research pushes back the earliest appearance of photosynthesizing organisms from 2.7 to 3.46 billion years ago.

Microscopic organisms such as cyanobacteria create oxygen as a by-product of photosynthesis.

The timing of their first appearance is hotly debated as it provides clues as to how early life on earth evolved.

Until now, the earliest evidence of photosynthesis was microscopic fossils found in shale rocks in Western Australia dating from 2.7 billion years ago.

Now, a team of Japanese, US and Australian scientists, led by Dr Masamichi Hoashi of the Kagoshima University, Japan, have found evidence for oxygen in ancient sea water from marine sedimentary rocks in the Pilbara region of Western Australia.

The evidence comes from tiny crystals of the iron-oxide mineral haematite in a 160-metre-long core section that forms part of the Marble Bar Chert.

Haematite can form in the presence of aerobic (oxygen-loving) bacteria in the water, or by photo-electric processes in the upper 10 metres of seawater.

According to the researchers, haematite crystals in the Marble Bar Chert formed in water at least 200 meters deep, because microscopic analysis of the rocks show no sign of wave action or other structures characteristic of shallow-water sediments.

The orientation and nature of the grains of haematite also show that it precipitated directly from the seawater, rather than forming later from other processes, such as the movement of groundwater, they added.

“These data strongly suggest that oxygenic photoautotrophs flourished in the photic zone of the 3.46 billion-year-old oceans and supplied molecular oxygen to the deep water,” said the researchers.

Professor Hiroshi Ohmoto from the NASA Astrobiology Institute and Department of Geosciences at the Pennsylvania State University said that other data backs their claim for an early development of photosynthesizing life.

“Recently accumulated massive amounts of geochemical and biochemical data can be better explained by a theory postulating the emergence of oxygenic photosynthesis and the development of a fully oxygenated atmosphere in the very early evolutionary stage,” said Ohmoto.

“Once cyanobacteria appeared in one area of the ocean, it probably took less than 10 million years to fully oxygenate the atmosphere and oceans,” he added. (ANI)

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Scientists describe novel strategy for phytoplankton growth in nutrient-poor areas of sea

March 11, 2009 By admin Leave a Comment

Washington, March 11 (ANI): An international team of scientists has described a novel strategy for phytoplankton growth in the vast nutrient-poor habitats of tropical and subtropical seas.

Until now, it was thought that all cells are surrounded by membranes containing molecules called phospholipids – oily compounds that contain phosphorus, as well as other basic elements including carbon and nitrogen.

These phospholipids are fundamental to the structure and function of the cell and for this reason had been thought to be an indispensable component of life.
hospholipids are one of several classes of molecules that contain the element phosphorus, which has been shown to be in very short supply in many marine ecosystems.

The deep sea contains ample phosphorus, but delivery to the surface waters where photosynthesis occurs is limited by temperature-induced stratification and the inability to mix the ocean to depths where phosphorus is available.

Research conducted at Station ALOHA near Hawaii during the past two decades has shown that phosphorus is rapidly becoming less abundant in the stratified regions of the North Pacific Ocean, possibly a result of changes in the marine habitat due to greenhouse gas warming.

Benjamin Van Mooy of the Woods Hole Oceanographic Institution and colleagues discovered that phytoplankton in the open ocean may be adapting to the low levels of phosphorus by making a fundamental change to their cell structure.

Rather than synthesizing the phosphorus-requiring phospholipids for use in their membranes, the plants appear to be using non-phosphorus containing “substitute lipids” that use the nearly unlimited element sulfur also found in seawater instead of phosphorus.

These substitute sulfolipids apparently allow the plants to continue to grow and survive under conditions of phosphorus stress, a unique strategy for life in the sea.

To test the generality of this biochemical strategy, the researchers compared the response of the phytoplankton communities in different ocean basins that experience varying levels of phosphorus stress.

In regions where phosphorus stress is extreme, such as the area dubbed the Sargasso Sea in the central North Atlantic Ocean, phospholipids were nearly nonexistent.

By comparison, in the South Pacific Ocean, where sufficient phosphorus exists, there were large amounts of phospholipids.

The region around Hawaii was intermediate, which is consistent with the long-term data sets from the Hawaii Ocean Time-series program showing that phosphorus is still measurable but is disappearing from the surface waters at an alarming rate.

One prediction from this initial study is that the phytoplankton in Hawaiian waters are likely to become more like those in the Sargasso Sea over time as phosphorus supplies dwindle further. (ANI)

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IRRI inks rice research pact with India

January 20, 2009 By Rajesh Leave a Comment

New Delhi, Jan.20 (ANI): An international agreement signed today between the International Rice Research Institute (IRRI) and the Indian Council of Agricultural Research (ICAR) will support and facilitate India’s rice research for the next three years, helping the nation’s rice production at a time of unprecedented price volatility and subsequent need for the revitalization of food production.

The work plan includes agreements on three major projects supported by the Bill and Melinda Gates Foundation: Stress-tolerant rice for poor farmers in Africa and South Asia (STRASA), the Cereal systems initiative for South Asia (CSISA), and Creating the second green revolution by supercharging photosynthesis: C4 rice.

STRASA aims to develop and distribute improved varieties of rice that can be grown in rainfed ecosystems, where farmers have little or no access to irrigation, and that can withstand environmental stresses such as drought, submergence, and salinity.

CSISA’s 10-year goal is to produce an additional five million tons of grain annually and increase the yearly incomes of 6 million poor rural households by at least USD 350. The initiative will employ innovative public-private partnerships for delivery of technology to farmers.

By converting rice from so-called C3 photosynthesis to the more efficient C4 photosynthesis, the C4 project aims to develop rice plants that can produce 50 percent more grain using less fertilizer and less water.

“The agreement will develop, promote, and accelerate rice research and training efforts between IRRI and ICAR,” said Dr. Robert S. Zeigler, IRRI director general. “The renewed collaboration will also provide important support for India’s other investments in agriculture and help India strengthen its science capacity.”

“The work plan focuses on conserving, evaluating, and enhancing genetic resources,” added Dr. Mangala Rai, ICAR director general, “as well as enhancing the productivity and sustainability of intensive cereal systems; improving productivity and livelihood for fragile environments; assessing the impact of, mitigation of, and adaptation to climate change; and strengthening linkages between research and development, including training.” (ANI)

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