Category: Science

It’s a murder plot played out both in fiction and real life. But now the first known case of murder using insulin has been seen in the natural world, and in a humble mollusc no less.

Cone snails are master hunters, carrying a cocktail of neurotoxins. Most have a lightning fast venomous dart that snags and paralyses unsuspecting fish. But some use their stretchy mouths to slowly capture and eat fish whole. Given how much quicker a fish is, you might wonder how the snails manage to do this.

It now seems the fish don’t put up a fight against the engulfing mouth because they have hypoglycaemic shock. Cone snails that use this technique – Conus geographus and Conus tulipa – spray a cocktail of toxins including an unusual type of insulin into the water to confuse and weaken the fish, letting them eat them whole.

Insulin is a hormone used throughout the animal kingdom to remove excess glucose from blood. But if you have too much insulin, your glucose levels drop and you become disoriented, confused and you can eventually lose consciousness and die.

The cone snails appear to subvert insulin’s normal physiological role to use it as an offensive weapon.

Although insulin has been used in dozens of real, and fictional, murders nobody has seen it used as a venom in the natural world.

So when Helena Safavi-Hemami from the University of Utah in Salt Lake City and her colleagues found that some cone snails produce insulin in their venom, they were taken aback. “It was very surprising to us since it had never been shown before and people have worked on animal venoms for decades,” says Safavi-Hemami.

The team delved further and found genes that produce the insulin are expressed at high levels on the tip of the venom gland. Last year, Richard Lewis from the University in Queensland in Australia showed that part of the gland is used to spray venom into the water.

Safavi-Hemami’s team also found that the insulin produced by the cone snails for use on fish is different from the one it uses to manage its own sugar levels. For one thing it’s the smallest insulin molecule ever seen. For another, it is much more like insulin used by fish than that seen in molluscs.

When the team injected it into zebrafish, it elicited hypoglycaemic shock. When they added it to water in which the fish swam, the fish immediately became sluggish, moving around much less than normal.

The small size of the weaponised insulin molecule could explain how it works so fast, says Safavi-Hemami.

And if the weaponised insulin is unusually fast-acting or potent, she says, it could help researchers understand how small changes in insulin molecules affect their function, and potentially lead to better treatments for diabetes.

The team is now analysing the genes in the cone snail that code for the insulin to figure out whether the snails developed the weaponised insulin from scratch or evolved it from the mollusc’s own insulin.

“It’s believed that vertebrate insulins have evolved from ancestral invertebrate genes,” says Safavi-Hemami. “Whether this is also true for the insulin we found cannot be answered yet.”

Lewis says the work provides good evidence that insulin is used to attack fish.

“Although precisely how it is used for defence and predation requires confirmation with direct experimentation,” he says, noting his team is currently doing that work.

Gabon was a French colony when prospectors from the French nuclear energy commissariat (the industrial parts, which later became the COGEMA and later Areva NC) discovered uranium in the remote region in 1956. France immediately opened mines operated by Comuf (Compagnie des Mines d’Uranium de Franceville) nearMounana village in order to exploit the vast mineral resources and the State of Gabon was given a minority share in the company.

For forty years, France mined for uranium in Gabon. Once extracted, the uranium was used for electricity production in France and much of Europe. Today, however, the uranium deposits are exhausted, and the mine is no longer worked. Currently, mine reclamation work is ongoing in the region affected by the mine operations.

There is strong geochemical evidence that the Oklo uranium deposit behaved as a natural nuclear fission reactor in Precambrian times: some of the mined uranium was found to have a lower concentration ofuranium-235 than expected, as if it had already been in a reactor. Geologists found that it had been in a reactor before—two billion years ago. At that time the natural uranium had a concentration of about 3% ²³⁵U, and could have gone critical with natural water as neutron moderator.

During a routine flight over the Antarctic ice shelf on 20 December last year, geophysicist Christian Müller spotted something strange: a huge, 2-kilometre-wide circle on the ice.

Müller, a contractor with research consultants Fielax from Bremerhaven, Germany, was in Antarctica as part of a polar survey conducted by the German Alfred Wegener Institute. Six days after spotting the weird ice-ring, he and his colleagues returned and flew over the site at two different altitudes, to photograph and scan it. Their working theory is that the ring marks an ice crater left by a large meteorite that slammed into Antarctica in 2004.

Two previous studies seem to back up this theory. First, a trail of dust was seen 30 kilometres above Antarctica on 3 September 2004. An Australian team speculated at the time that this was the remnants of one of the largest meteoroids to have entered Earth’s atmosphere during the decade (Nature, 10.1038/nature03881).

Second, in 2007, another team used global infrasound (low-frequency sound) data to triangulate the location of a big bang that was picked up by remote sensors on that same date (Earth, Moon and Planets, 10.1007/s11038-007-9205-z. They pinpointed the Antarctic ice shelf, very close to where Müller spotted his ice crater and speculated the bang had been made by a meteoroid the size of a house.

Müller and his colleagues say their theory still needs to be carefully checked out, and will be conducting further studies.

A raindrop hitting sand may not make the deep impact of an asteroid strike, but crash tests are showing that they leave behind a similar crater.

Xiang Cheng from the University of Minnesota in Minneapolis and colleagues released drops of water onto a bed of tiny glass beads, varying the impact energy to observe the resulting mini-Armageddon.

The team was surprised to find that craters formed by liquids have the same shape as an asteroid strike. Their shape also varies with the strength of impact in the same way.

The real value of these results is how they help us understand splashing liquids – which are more of a mystery than collisions between solid objects. They could help us predict the effect of rain on soil erosion or design better drip irrigation systems.

Journal reference: PNAS, DOI: 10.1073/pnas.1419271112

When lava meets snow at the volatile Tolbachik volcano in far eastern Russia, they eject jets of steam as they battle it out. But a look beneath the surface reveals surprising differences in the way the two interact, depending on the type of lava.

Ben Edwards of Dickinson College in Carlisle, Pennsylvania, and colleagues observed lava as the volcano erupted during the winter of 2013. They dug daring observation pits in front of advancing lava flows to identify how it moved through the snow.

As shown in these videos, chunky a’a’ lava advances on top of the rigid snowpack in a rolling caterpillar-like motion, on a layer of melting water. The lava forms a thick tongue that can travel hundreds or thousands of metres.

In contrast, as smoother pahoehoe lava advances, the front of the flow moves under a snowpack, up to 2 metres below the surface. The lava expands beneath the snow, causing steam to shoot up as it mixes with meltwater. It also pushes snow upwards, building snow domes that turn into blocks strewn across the surface as they melt.

The distinctive patterns that result could serve as a fingerprint that identifies where ancient lava has flowed over snow, revealing more about Earth’s climate in the distant past – or even giving clues about the icy, lava-soaked history of Mars.

Boom: North America’s Explosive Oil-By-Rail Problem from Weather Films on Vimeo.

Boom is a terrifying documentary on a problem that you may not be aware of: America has been invaded by hundred of thousands of moving fire bombs—freight trains with old, cheap tanker cars designed to transport corn oil filled with dangerous flammable oil. Logically, accidents are happening, people are dying, and oil is spilling.

As production kept increasing, the oil-by-train transport business grew from 9,500 carloads of crude oil in 2008 to more than 400,000 tankers in 2013, each carrying 30,000 gallons. Many trains carry as much as one hundred cars. Naturally, the list of accidents keeps increasing:

• A train hauling 2.9 million gallons of Bakken oil derailed and exploded on November 8 in Aliceville, Alabama, and the oil that leaked but did not burn continues to foul the wetlands in the area.
• On December 30th, a train collision in Casselton, North Dakota 20 miles outside of Fargo, prompted a mass evacuation of over half the town’s residents after 18 cars exploded into fireballs visible for miles. 400,000 gallons of oil spilled after that accident, which involved two trains traveling well below local speed limits.
• Around 1AM on July 5, 2013, over 60 oil cars exploded after a runaway train derailed in Lac-Megantic, a Canadian town near the Maine border, leveling dozens of buildings and killing 47 of the town’s roughly 6,000 residents.

Sounds bad? It gets worse: The U.S. government says that freight train accidents spilled 1.15 million gallons of crude oil just in 2013. For comparison, the average amount from 1975 to 2012 was 22,000 gallons a year.

According to a New York Times’ story, the bad news don’t stop there: Not only they are putting every city and town with a railroad at risk, we are all paying for it: “States and the federal government have handed out tens of millions in public dollars to rail companies and government agencies to expand crude oil rail transportation across the country.”

Examination of DNA from 21 primate species – from squirrel monkeys to humans – exposes an evolutionary war against infectious bacteria over iron that circulates in the bloodstream. Supported by experimental evidence, these findings, published in Science on Dec. 12, demonstrate the vital importance of an underappreciated defense mechanism, nutritional immunity.

“We’ve known about nutritional immunity for 40 years,” says Matthew Barber, Ph.D., first author and postdoctoral fellow in human genetics at the University of Utah. “What this study shows us is that over the last 40 million years of primate evolution, this battle for iron between bacteria and primates has been a determining factor in our survival as a species.” The study models an approach for uncovering reservoirs of genetic resistance to bacterial infections, knowledge that could be used to confront antibiotic resistance and emerging diseases.

Following infection, the familiar sneezing, runny nose, and inflammation are all part of the immune system’s attempts to rid the body of hostile invaders. Lesser known is a separate defense against invasive microbes, called nutritional immunity, that quietly takes place under our skin. This defense mechanism starves infectious bacteria by hiding circulating iron, an essential nutrient it needs for survival. The protein that transports iron in the blood, transferrin, tucks the trace metal safely out of reach.

Clever as it sounds, the ploy is not enough to keep invaders at bay. Several bacterial pathogens – including those that cause meningitis, gonorrhea, and sepsis – have developed a weapon, transferrin binding protein (TbpA), that latches onto transferrin and steal its iron. Though scientists have known of the offensive strategy, they failed to realize how pivotal the battle over iron has been in the conflict between host and pathogen.

“Interactions between host and pathogen are transient and temporary,” says senior author Nels Elde, Ph.D., assistant professor of human genetics at the University of Utah. “It took casting a wide net across all of primate genetic diversity to capture the significance.”

Just as details of a struggle can be gleaned from battle scars, Barber and Elde reconstructed this evolutionary conflict by documenting when and where changes in transferrin and TbpA have occurred over millennia. They examined the DNA of transferrin in 21 species from the primate family tree, and of TbpA from dozens of bacterial strains. The majority of accumulated changes in transferrin and TbpA cluster around a single region of contact between the two proteins, highlighting it as a site of evolutionary conflict between host and pathogen. The authors then used these genetic observations as a guide to perform experiments, which showed changes in TbpA enable the protein to grasp hold of transferrin, and that recent changes in transferrin allow it to evade TbpA.

Up to 25 percent of people in the world’s populations have a small alteration in the transferrin gene, which prevents recognition by several infectious bacteria, the most recent sign of this long battle. “Up until this study no one had come up with a functional explanation for why this variation occurs at an appreciable frequency in human populations,” says Elde. “We now know that it is a consequence of the pathogens we and our ancestors faced over millions of years.”

Understanding the strategies that underlie natural defense mechanisms, including nutritional immunity, could inform new approaches to combatting antibiotic-resistant bacteria and emerging diseases. “By examining the natural conflicts that have played out for millions of years, we can determine what has worked, and apply them in new situations,” says Elde.

Escape from iron piracy through rapid evolution of transferrin. MF Barber, NC Elde, Science Dec 12, 2014

The work was supported by awards from the Pew Charitable Trusts and the National Institutes of Health

Yuletide 24 from NATS on Vimeo.

Lovely analysis from from astronomer and astrophysicist Linda Harden.

1. No known species of reindeer can fly. BUT there are 300,000 species of living organisms yet to be classified, and while most of these are insects and germs, this does not COMPLETELY rule out flying reindeer which only Santa has ever seen.
2. There are 2 billion children (persons under 18) in the world. BUT since Santa doesn’t (appear to) handle the Muslim, Hindu, Jewish and Buddhist children, that reduces the workload to 15% of the total – 378 million according to Population Reference Bureau. At an average (census)rate of 3.5 children per household, that’s 91.8 million homes. One presumes there’s at least one good child in each.
3. Santa has 31 hours of Christmas to work with, thanks to the different time zones and the rotation of the earth, assuming he travels east to west(which seems logical). This works out to 822.6 visits per second. This is to say that for each Christian household with good children, Santa has 1/1000th of a second to park, hop out of the sleigh, jump down the chimney, fill the stockings, distribute the remaining presents under the tree, eat whatever snacks have been left, get back up the chimney, get back into the sleigh and move on to the next house. Assuming that each of these 91.8 million stops are evenly distributed around the earth (which, of course, we know to be false but for the purposes of our calculations we will accept), we are now talking about .78 miles per household, a total trip of 75-1/2 million miles, not counting stops to do what most of us must do at least once every 31 hours, plus feeding etc.
4. This means that Santa’s sleigh is moving at 650 miles per second, 3,000 times the speed of sound. For purposes of comparison, the fastest man- made vehicle on earth, the Ulysses space probe, moves at a poky 27.4 miles per second – a conventional reindeer can run, tops, 15 miles per hour.
5. The payload on the sleigh adds another interesting element. Assuming that each child gets nothing more than a medium-sized lego set (2 pounds), the sleigh is carrying 321,300 tons, not counting Santa, who is invariably described as overweight. On land, conventional reindeer can pull no more than 300 pounds. Even granting that “flying reindeer” (see point #1) could pull TEN TIMES the normal anoint, we cannot do the job with eight, or even nine. We need 214,200 reindeer. This increases the payload – not even counting the weight of the sleigh – to 353,430 tons. Again, for comparison – this is four times the weight of the Queen Elizabeth.
6. 353,000 tons traveling at 650 miles per second creates enormous air resistance – this will heat the reindeer up in the same fashion as spacecrafts re-entering the earth’s atmosphere. The lead pair of reindeer will absorb 14.3 QUINTILLION joules of energy. Per second. Each. In short, they will burst into flame almost instantaneously, exposing the reindeer behind them, and create deafening sonic booms in their wake.The entire reindeer team will be vaporized within 4.26 thousandths of a second. Santa, meanwhile, will be subjected to centrifugal forces 17,500.06 times greater than gravity. A 250-pound Santa (which seems ludicrously slim)would be pinned to the back of his sleigh by 4,315,015 pounds of force.

In conclusion — If Santa ever DID deliver presents on Christmas Eve, he’s dead now.