A zinc compound sometimes taken to treat the common cold might have a second career as emergency treatment for anyone unlucky enough to get stung by an Australian box jellyfish, a new study finds. Researchers also find that venom from stings seems to poke holes in red blood cells, triggering the release of potassium that stops the heart when tested in mice. 
Box jellyfish (Chironex fleckeri), which roam the seas off northern Australia, deliver some of the most potent venom found in nature. In the last decade, scientists have shown that the venom can create pores in cells, spilling their contents. But the fundamental aspects of the venom’s lethality have been poorly understood.
Australian researchers have proposed that the venom attacks heart muscle cells, which would explain why sting victims sometimes suffer cardiac arrest. But in the new study, published online December 12 in PLOS ONE, Angel Yanagihara and Ralph Shohet of the University of Hawaii in Honolulu report that reinforced pores form in red blood cells exposed to the box jellyfish’s venom.
“These are structurally sound rings of pores that are catastrophic for cells,” says Yanagihara, a biochemist. While the venom can damage any cell, she says, her lab experiments showed that red blood cells formed the pores within 20 minutes of exposure to the venom, triggering potassium discharge. That, she suggests, alters the delicate balance of electrolytes that govern the electrical signals that keep the heart beating. Too much potassium in the blood is fatal.
In tests in mice, animals given a dose of the venom had aberrant heartbeats within 90 seconds, and their hearts showed steadily deteriorating ability to contract afterward. That is consistent with potassium poisoning. But when the scientists treated eight mice with zinc gluconate after exposure to the venom, four survived more than 12 hours. Untreated mice exposed to the venom died within an average of 19 minutes. Mice receiving a standard box jellyfish antivenom died as fast as those getting no medication.
The zinc compound blocks assembly of the pores, stanching potassium discharge, tests in red blood cells show.
The findings offer a “plausible explanation” for the rapid death sometimes seen after box jellyfish stings, says Kenneth Winkel, director of the Australian Venom Research Unit at the University of Melbourne. But he says more work is needed to prove that blood cells, and not heart cells, are the main targets. And while he says the zinc findings create opportunities for further work on zinc as a treatment, Winkel sees zinc as a potential add-on to the standard antivenom, an antibody-based drug aimed at neutralizing the toxin.
Yanagihara cautions that the antivenom not only failed to protect mice in her tests but may have made matters worse. “The fast-acting agent in the venom would be far too quick for an antibody-based approach,” she concludes.

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Some of the fossils celebrated as sea life’s big breakout beyond mere soups and slimes might actually have dwelled on land, argues a controversial new study.
Named the Ediacaran fauna after Australia’s Ediacara Hills, these creatures dating from roughly 575 million to 542 million years ago mark life finally growing beyond the microscopic. Found in some 30 locations around the world, Ediacarans grew in discs, fronds and other fairly simple shapes with a quilted look, and paleontologists usually consider them some sort of marine creatures.
A new detailed analysis of the rocks where Australian Ediacarans are found suggests the rocks are fossilized soils, or paleosols, instead of a sea bottom, says Gregory Retallack of the University of Oregon in Eugene. The placement of fossils and tiny tubes in the rocks suggests to him that at least some of the Ediacarans actually lived in those soils instead of just washing up on them.
Retallack received “some pushback,” as he calls it, for earlier proposals that Ediacarans were not sea animals but land-living lichens. With the new study, published online December 12 in Nature, he says he knew “people were going to be irate.”
If Ediacarans did turn out to be terrestrial, the implications would go far beyond rethinking where Earth’s earliest complex multicellular organisms lived, says longtime Ediacaran researcher Guy Narbonne of Queen’s University in Kingston, Canada. He doesn’t agree with the new results, but if they were correct, it could mean that decades of studies of ancient environments were based on flawed assumptions.
Also, putting some Ediacarans on soil would add a chapter to the story of life adapting to land. The specimens Retallack studied were about 550 million years old and would be the first big organisms (larger than 2 centimeters) on land. There’s plausible evidence for smaller life that early, he says. But the great rise of seed-making land plants was still some hundred million years in the future.
Retallack has specialized in analyzing ancient soils, but only in recent years has he analyzed in detail at the Australian geological formations that hold the Ediacarans. The rocks show soillike gradations in titanium and some other elements, he says. Patterns of uncommon forms, or isotopes, of carbon and oxygen track each other as they would in soils.
Gypsum crystals and some other nodules are junked up with internal grains of sand that Retallack would not expect if the structures had formed with plenty of water around. He saw cracked and nubbly texture like old elephant skin that he would expect to see on a soil surface. The red color comes from ancient exposure to air instead of more recent weathering, he says.
What he’s found, Retallack suggests, could have been somewhat like modern tundra. Some Ediacarans appear to have grown in these soils, he says. Fossils he’s examined, such as disclike Dickinsonia, look embedded in the fossilized soil without overlapping and show a range of growth stages. In microscopic views of the fossilized soils, he saw tiny tubes branching like modern fungal filaments or cyanobacterial ropes.
“Unconvincing,” says Shuhai Xiao of Virginia Tech in Blacksburg. He says he still thinks ocean processes could explain the Ediacaran rock details. The weight of overlying rock underwater might have deformed a surface into the bumpy elephant-skin texture, for example.
And then there are the other places around the world where Ediacaran fossils show up, protests paleobiologist Mary Droser of the University of California, Riverside. “Where most of the fossils occur are not beds that anyone would consider anything but shallow marine,” she says. Many fossils, for example, show up in rocks with wave-generated ripples as well as underwater-style hummocks and swales.

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An international effort has put together the first tally of all the species of butterflies, beetles, ants, bees, roaches and their fellow arthropods that live in a tropical forest. And the count: 25,000.
Arthropods represent a big chunk of the diversity of species on Earth, but biologists analyzing such basic questions as how forest ecosystems will respond to climate change haven’t had much solid data on what’s really scurrying, flying and buzzing through those forests. To get a better sense, a team of 102 researchers from 21 countries sampled arthropods in the San Lorenzo forest, a 60-square-kilometer tropical forest in Panama.
Researchers collected samples from the soil on up to the treetops using professional tree climbers, a crane, even a helium-filled balloon to extend their reach. Then came eight years of determining the species for 129,000 individual specimens.

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NASA’s twin GRAIL probes are on a crash course to hit the lunar surface on December 17.
The cosmic collision is intentional: Mission engineers need to guide the spacecraft down because they have run out of fuel to keep themselves in lunar orbit. Scientists will be watching until the very end, because how GRAIL hits may yield more discoveries about the moon.
GRAIL consists of two washing machine–sized probes named Ebb and Flow. Launched in September 2011, they arrived in January and completed their main task of mapping lunar gravity between March and May. GRAIL’s discoveries include the fact that the moon’s crust is thinner and more fractured by meteorite impacts than scientists had suspected (SN Online: 12/6/12).
But Ebb and Flow will meet their ends at 5:28 and 5:29 p.m. Eastern time on December 17. NASA will guide them at a very shallow angle into the side of a small mountain, part of the rim of an impact crater. The collision will take place in the dark, but far overhead the Lunar Reconnaissance Orbiter satellite will photograph the crash site before and after the event. By comparing those pictures, scientists will able to see how much of the mountain’s rock was broken up during the crash — and know how intact the lunar crust is at that spot, says the mission’s chief scientist, MIT geophysicist Maria Zuber.

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