What’s the News: For the first time, astronomers have found molecular oxygen, which makes up about 20 percent of our air on Earth, in space. Using the large telescope aboard the Herschel Space Observatory, a team of researchers from the European Space Agency and NASA detected the simple molecule in a star-forming region of the Orion Nebula, located about 1,500 light-years from Earth. This takes astronomers one step closer to discovering where all of the oxygen in space is hiding.
When the news comes from Saturn’s moons, the source is typically Titan—with its hazy atmosphere and frigid surface lakes of methane—or Enceladus—with its plumes of water ice. Last week, however, word came that Rhea, the second-largest Saturnian satellite, has some surprises of its own.
In Friday’s edition of Science, a study by Ben Teolis and colleagues confirmed that during a pass of the moon in March, when the ever-reliable Cassini spacecraft cruised over Rhea’s pole at an altitude of just 60 miles, it directly sampled tiny amounts of oxygen and carbon dioxide there.
“This really is the first time that we’ve seen oxygen directly in the atmosphere of another world,” said Andrew Coates, at UCL’s Mullard Space Science Laboratory, a co-author of the study. [The Guardian]
A huge spike in the Earth’s atmospheric oxygen about 800 million years ago, the story goes, paved the way for the Cambrian explosion a couple hundred million years later, and with it the rise of complex life. But a new study out in Nature says that picture is incomplete. Researchers found evidence of substantial oxygen 1.2 billion years ago, meaning that the conditions needed for complex life appeared much earlier than scientists knew, and that perhaps something else was required to set off the explosion of biodiversity.
The geologists led by John Parnell hunted in the Scottish Highlands for clues in ancient rocks, where evidence of ancient bacteria could reveal how much oxygen was around 1.2 billion years ago.
Before there was a useful amount of free oxygen around, these bacteria used to get energy by converting sulfate, a molecule with one sulfur atom and four oxygens, to sulfide, a sulfur atom that is missing two electrons. Geologists can get a glimpse of how efficient the bacteria were by looking at two different sulfur isotopes, versions of the same element that have different atomic masses. Converting sulfate to sulfide leaves the rock with a lot more of the isotope sulfur-32 than would be there without the bacteria’s help. [Wired.com]
After a quarter-million scientific papers, you’d better hope your methodology was solid.
Most of the studies you’ve probably heard of that try to tie a specific region of the brain to an action or feeling probably relied on a functional MRI technique that tracks the flow of oxygenated blood–so when you see a region “light up” on an fMRI image, that’s not the fMRI picking up the actual neurons firing. Rather, it watches for small changes in blood oxygen levels in the region. This method, called blood oxygenation level-dependence (BOLD), presumes that active neurons use more energy and thus require more oxygen. Now, in a study in Nature, researchers at Stanford Medical Center have provided direct evidence that the inference is correct.
Lead researcher Karl Deisseroth employed a technique called optogenetics to prove the point. He and his colleagues engineered brain cells that respond to a flash of blue light; when they did this trick on cells in the motor cortex of rats, the flash of light acted as a trigger to active the neurons there. The idea was that they would examine these rats with fMRI at the same time they stimulated those motor neurons with the blue light. If the fMRI lit up in the same places where the researchers knew they were stimulating neurons, they could be confident that fMRI was really picking up brain activation.
Sure enough, when the neurons were turned on with a pulse of blue light, the researchers detected a strong BOLD signal emanating from the motor cortex neurons’ neighborhood. The BOLD signals were exactly what was expected. “It was very compelling and reassuring,” Deisseroth says. “Everyone can breathe a sigh of relief” [Science News].
It took more than being woolly for woolly mammoths to survive the wintry climates in which they lived. A new study in Nature Genetics suggests that the weighty mammals had hemoglobin in their blood that could keep oxygen moving even at low temperatures, giving them a kind of “antifreeze” blood:
For the mammoth, this meant that they could keep extremities cool and concentrate heat internally, minimizing heat loss. In addition, it meant that when food was scarce they could live on less of it since they didn’t need as much heat (or calories) to move the oxygen to the tissues [The Guardian].
Researchers figured this out through a lengthy process of analyzing 43,000-year-old mammoth remains unearthed in Siberia. But to understand the secrets of this huge creature, they had to enlist the help of a microorganism.
The mammoth DNA sequences were converted into RNA (a molecule similar to DNA which is central to the production of proteins) and inserted into E. coli bacteria. The bacteria faithfully manufactured the mammoth protein. “The resulting haemoglobin molecules are no different than ‘going back in time’ and taking a blood sample from a real mammoth,” said co-author Kevin Campbell, from the University of Manitoba in Canada [BBC News].
Microorganisms can live the far reaches of the planet, in extreme temperatures and pressures, and in some cases even without oxygen. But now scientists say they have found the first multicellular organisms inhabiting an anoxic environment. In other words: They’ve found the first animals living without oxygen.
They belong to the group called loriciferans, a phylum of creatures that live in marine sediment. About a millimeter long, they look something like a half-jellyfish, half-crab. The beasts live in conditions that would kill every other known animal. As well as lacking oxygen, the sediments are choked with salt and swamped with hydrogen sulphide gas [New Scientist].
Roberto Danovaro and his colleagues, who documented this find in BMC Biology, had been searching the salty, oxygen-free depths of the Mediterranean Sea down below 10,000 feet for life. When previous searches turned up animal bodies, he says, researchers wrote them off, thinking they had fallen to those depths from oxygenated waters closer to the surface. But Danovaro says his team recovered living loriciferans from the area, including ones with eggs.