Theory on origin of animals challenged: Some animals need extremely little oxygen

One of science’s strongest dogmas is that complex life on Earth could only evolve when oxygen levels in the atmosphere rose to close to modern levels. But now studies of a small sea sponge fished out of a Danish fjord shows that complex life does not need high levels of oxygen in order to live and grow.The origin of complex life is one of science’s greatest mysteries. How could the first small primitive cells evolve into the diversity of advanced life forms that exists on Earth today? The explanation in all textbooks is: Oxygen. Complex life evolved because the atmospheric levels of oxygen began to rise app. 630 — 635 million years ago.However new studies of a common sea sponge from Kerteminde Fjord in Denmark shows that this explanation needs to be reconsidered. The sponge studies show that animals can live and grow even with very limited oxygen supplies.In fact animals can live and grow when the atmosphere contains only 0.5 per cent of the oxygen levels in today’s atmosphere.”Our studies suggest that the origin of animals was not prevented by low oxygen levels,” says Daniel Mills, PhD at the Nordic Center for Earth Evolution at the University of Southern Denmark.Together with Lewis M. Ward from the California Institute of Technology he is the lead author of a research paper about the work in the journal PNAS.A little over half a billion years ago, the first forms of complex life — animals — evolved on Earth. Billions of years before that life had only consisted of simple single-celled life forms. The emergence of animals coincided with a significant rise in atmospheric oxygen, and therefore it seemed obvious to link the two events and conclude that the increased oxygen levels had led to the evolution of animals.”But nobody has ever tested how much oxygen animals need — at least not to my knowledge. …

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Blind mole-rats are resistant to chemically induced cancers

Sep. 3, 2013 — Like naked mole-rats (Heterocephalus gaber), blind mole-rats (of the genus Spalax) live underground in low-oxygen environments, are long-lived and resistant to cancer. A new study demonstrates just how cancer-resistant Spalax are, and suggests that the adaptations that help these rodents survive in low-oxygen environments also play a role in their longevity and cancer resistance.The findings are reported in the journal Biomed Central: Biology.”We’ve shown that, compared to mice and rats, blind mole-rats are highly resistant to carcinogens,” said Mark Band, the director of functional genomics at the University of Illinois Biotechnology Center and a co-author on the study. Band led a previous analysis of gene expression in blind mole-rats living in low-oxygen (hypoxic) environments. He found that genes that respond to hypoxia are known to also play a role in aging and in suppressing or promoting cancer.”We think that these three phenomena are tied in together: the hypoxia tolerance, the longevity and cancer resistance,” Band said. “We think all result from evolutionary adaptations to a stressful environment.”Unlike the naked mole-rat, which lives in colonies in Eastern Africa, the blind mole-rat is a solitary rodent found in the Eastern Mediterranean. Thousands of blind mole-rats have been captured and studied for more than 50 years at Israel’s University of Haifa, where the animal work was conducted. The Haifa scientists observed that none of their blind mole-rats had ever developed cancer, even though Spalax can live more than 20 years. Lab mice and rats have a maximum lifespan of about 3.5 years and yet regularly develop spontaneous cancers.To test the blind mole-rats’ cancer resistance, the Haifa team, led by Irena Manov, Aaron Avivi and Imad Shams, exposed the animals to two cancer-causing agents. Only one of the 20 Spalax tested (an animal that was more than 10 years old) developed malignant tumors after exposure to one of the carcinogens. …

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Morphing manganese: New discovery alters understanding of chemistry that moves elements through natural world

Aug. 22, 2013 — An often-overlooked form of manganese, an element critical to many life processes, is far more prevalent in ocean environments than previously known, according to a study led by University of Delaware researchers that was published this week in Science.The discovery alters understanding of the chemistry that moves manganese and other elements, like oxygen and carbon, through the natural world. Manganese is an essential nutrient for most organisms and helps plants produce oxygen during photosynthesis.”You wouldn’t think manganese is that important, but without manganese, we wouldn’t have the molecular oxygen that we breathe,” said study co-author George Luther, Maxwell P. and Mildred H. Harrington Professor of Oceanography in the School of Marine Science and Policy within UD’s College of Earth, Ocean, and Environment.Manganese is present in the environment in three forms — manganese(II), manganese(III) and manganese(IV) — the difference related to the oxidation state, or number of electrons present. When elements lose or gain an electron, the oxidation state changes in a “redox reaction,” like when iron turns into rust by losing electrons to oxygen in air.The second-most common metal in Earth’s crust, manganese rapidly changes between oxidation states while reacting with other elements in the environment.Traditionally, manganese(II) and manganese(IV) were believed to be the dominant forms in aquatic environments. But in the mid-2000s, Luther found in a surprising result that manganese(III) was also present in a Black Sea “transition zone,” an area where oxygen levels are relatively high near the surface but gradually diminish deeper down in the water.Suspecting that this intermediary form was far more widespread than the somewhat unique conditions of the Black Sea, he and his Canadian colleagues Bjørn Sundby of the University of Quebec at Rimouski and Al Mucci of McGill University, whom he has worked with more than 20 years, set out for the largest estuary in the world: the Gulf of Saint Lawrence off the southeast corner of Canada.There they pulled up samples of mud from the seafloor, where in the top few inches of sediment, there is also a transition zone of diminishing oxygen amounts. Andrew Madison, lead author on the Science paper and Luther’s former graduate student, used a new technique to differentiate between manganese forms.”It was a bit frustrating, and I spent about two and a half years working through methodological challenges and complications,” said Madison, who finished his doctorate last year and now works as geochemist at Golder Associates Inc. in New Jersey. “But it was also pretty rewarding when I finally got something to work.”His results showed that manganese(III) comprised up to 90 percent of the total manganese present in the Canadian study sites. …

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New water splitting technique efficiently produces hydrogen fuel

Aug. 1, 2013 — A University of Colorado Boulder team has developed a radically new technique that uses the power of sunlight to efficiently split water into its components of hydrogen and oxygen, paving the way for the broad use of hydrogen as a clean, green fuel.The CU-Boulder team has devised a solar-thermal system in which sunlight could be concentrated by a vast array of mirrors onto a single point atop a central tower up to several hundred feet tall. The tower would gather heat generated by the mirror system to roughly 2,500 degrees Fahrenheit (1,350 Celsius), then deliver it into a reactor containing chemical compounds known as metal oxides, said CU-Boulder Professor Alan Weimer, research group leader.As a metal oxide compound heats up, it releases oxygen atoms, changing its material composition and causing the newly formed compound to seek out new oxygen atoms, said Weimer. The team showed that the addition of steam to the system — which could be produced by boiling water in the reactor with the concentrated sunlight beamed to the tower — would cause oxygen from the water molecules to adhere to the surface of the metal oxide, freeing up hydrogen molecules for collection as hydrogen gas.”We have designed something here that is very different from other methods and frankly something that nobody thought was possible before,” said Weimer of the chemical and biological engineering department. “Splitting water with sunlight is the Holy Grail of a sustainable hydrogen economy.”A paper on the subject was published in the Aug. 2 issue of Science. The team included co-lead authors Weimer and Associate Professor Charles Musgrave, first author and doctoral student Christopher Muhich, postdoctoral researcher Janna Martinek, undergraduate Kayla Weston, former CU graduate student Paul Lichty, former CU postdoctoral researcher Xinhua Liang and former CU researcher Brian Evanko.One of the key differences between the CU method and other methods developed to split water is the ability to conduct two chemical reactions at the same temperature, said Musgrave, also of the chemical and biological engineering department. While there are no working models, conventional theory holds that producing hydrogen through the metal oxide process requires heating the reactor to a high temperature to remove oxygen, then cooling it to a low temperature before injecting steam to re-oxidize the compound in order to release hydrogen gas for collection.”The more conventional approaches require the control of both the switching of the temperature in the reactor from a hot to a cool state and the introduction of steam into the system,” said Musgrave. “One of the big innovations in our system is that there is no swing in the temperature. The whole process is driven by either turning a steam valve on or off.””Just like you would use a magnifying glass to start a fire, we can concentrate sunlight until it is really hot and use it to drive these chemical reactions,” said Muhich. …

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Suffocating tumors could lead to new cancer drugs

July 25, 2013 — Scientists have discovered a new molecule that prevents cancer cells from responding and surviving when starved of oxygen and which could be developed into new treatments for the disease, according to new research published in the Journal of the American Chemical Society on July 26.Cancer Research UK scientists at the University of Southampton found that this molecule targets the master switch — HIF-1 — that cancer cells use to adapt to low oxygen levels, a common feature in the disease.The researchers uncovered a way to stop cancer cells using this switch through an approach called ‘synthetic biology’. By testing 3.2 million potential compounds, made by specially engineered bacteria, they were able to find a molecule that stopped HIF-1 from working.All cells need a blood supply to provide them with the oxygen and nutrients they require to survive. Cancer tumours grow rapidly and as the tumour gets bigger it outstrips the supply of oxygen and nutrients that the surrounding blood vessels can deliver.But, to cope with this low-oxygen environment, HIF-1 acts as a master switch that turns on hundreds of genes, allowing cancer cells to survive. HIF-1 triggers the formation of new blood vessels around tumours, causing more oxygen and nutrients to be delivered to the starving tumour, which in turn allows it to keep growing.Dr Ali Tavassoli, a Cancer Research UK scientist whose team discovered and developed the compound at the University of Southampton, said: “We’ve found a way to target the steps that cancer cells take to survive and we hope that our research will one day lead to effective drugs that can stop cancers adapting to a low oxygen environment, stopping their growth. The next step is to further develop this molecule to create an effective treatment.”Dr Julie Sharp, senior science information manager at Cancer Research UK, said: “Finding ways to disrupt the tools that cancer cells use to adapt and grow when starved of oxygen has been a hot topic in cancer research, but finding drugs that do this effectively has proved elusive.”For the first time our scientists have found a way to block a master switch controlling cells response to low levels of oxygen — an important step towards creating drugs that could halt cancer in its tracks.”

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A new weapon against stroke

July 23, 2013 — One of regenerative medicine’s greatest goals is to develop new treatments for stroke. So far, stem cell research for the disease has focused on developing therapeutic neurons — the primary movers of electrical impulses in the brain — to repair tissue damaged when oxygen to the brain is limited by a blood clot or break in a vessel. New UC Davis research, however, shows that other cells may be better suited for the task.Published today in the journal Nature Communications, the large, collaborative study found that astrocytes — neural cells that transport key nutrients and form the blood-brain barrier — can protect brain tissue and reduce disability due to stroke and other ischemic brain disorders.”Astrocytes are often considered just ‘housekeeping’ cells because of their supportive roles to neurons, but they’re actually much more sophisticated,” said Wenbin Deng, associate professor of biochemistry and molecular medicine at UC Davis and senior author of the study. “They are critical to several brain functions and are believed to protect neurons from injury and death. They are not excitable cells like neurons and are easier to harness. We wanted to explore their potential in treating neurological disorders, beginning with stroke.”Deng added that the therapeutic potential of astrocytes has not been investigated in this context, since making them at the purity levels necessary for stem cell therapies is challenging. In addition, the specific types of astrocytes linked with protecting and repairing brain injuries were not well understood.The team began by using a transcription factor (a protein that turns on genes) known as Olig2 to differentiate human embryonic stem cells into astrocytes. This approach generated a previously undiscovered type of astrocyte called Olig2PC-Astros. More importantly, it produced those astrocytes at almost 100 percent purity.The researchers then compared the effects of Olig2PC-Astros, another type of astrocyte called NPC-Astros and no treatment whatsoever on three groups of rats with ischemic brain injuries. The rats transplanted with Olig2PC-Astros experienced superior neuroprotection together with higher levels of brain-derived neurotrophic factor (BDNF), a protein associated with nerve growth and survival. …

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Migrating animals add new depth to how the ocean ‘breathes’

June 24, 2013 — The oxygen content of the ocean may be subject to frequent ups and downs in a very literal sense — that is, in the form of the numerous sea creatures that dine near the surface at night then submerge into the safety of deeper, darker waters at daybreak.Research begun at Princeton University and recently reported on in the journal Nature Geoscience found that animals ranging from plankton to small fish consume vast amounts of what little oxygen is available in the ocean’s aptly named “oxygen minimum zone” daily. The sheer number of organisms that seek refuge in water roughly 200- to 650-meters deep (650 to 2,000 feet) every day result in the global consumption of between 10 and 40 percent of the oxygen available at these depths.The findings reveal a crucial and underappreciated role that animals have in ocean chemistry on a global scale, explained first author Daniele Bianchi, a postdoctoral researcher at McGill University who began the project as a doctoral student of atmospheric and oceanic sciences at Princeton.”In a sense, this research should change how we think of the ocean’s metabolism,” Bianchi said. “Scientists know that there is this massive migration, but no one has really tried to estimate how it impacts the chemistry of the ocean.”Generally, scientists have thought that microbes and bacteria primarily consume oxygen in the deeper ocean,” Bianchi said. “What we’re saying here is that animals that migrate during the day are a big source of oxygen depletion. We provide the first global data set to say that.”Much of the deep ocean can replenish (often just barely) the oxygen consumed during these mass migrations, which are known as diel vertical migrations (DVMs).But the balance between DVMs and the limited deep-water oxygen supply could be easily upset, Bianchi said — particularly by climate change, which is predicted to further decrease levels of oxygen in the ocean. That could mean these animals would not be able to descend as deep, putting them at the mercy of predators and inflicting their oxygen-sucking ways on a new ocean zone.”If the ocean oxygen changes, then the depth of these migrations also will change. We can expect potential changes in the interactions between larger guys and little guys,” Bianchi said. “What complicates this story is that if these animals are responsible for a chunk of oxygen depletion in general, then a change in their habits might have a feedback in terms of oxygen levels in other parts of the deeper ocean.”The researchers produced a global model of DVM depths and oxygen depletion by mining acoustic oceanic data collected by 389 American and British research cruises between 1990 and 2011. Using the background readings caused by the sound of animals as they ascended and descended, the researchers identified more than 4,000 DVM events.They then chemically analyzed samples from DVM-event locations to create a model that could correlate DVM depth with oxygen depletion. With that data, the researchers concluded that DVMs indeed intensify the oxygen deficit within oxygen minimum zones.”You can say that the whole ecosystem does this migration — chances are that if it swims, it does this kind of migration,” Bianchi said. …

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