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Charles Hedgcock, © 2015 Wendy Moore

Inside the Toxic Explosion Shooting Out of a Beetle’s Butt

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Charles Hedgcock, © 2015 Wendy Moore
Bombardier beetles share their name with Air Force crews who drop bombs for a reason. When under attack, the beetles, native to much of the world, expel a noxious jet of scalding chemicals at their enemies.

As part of a study published in Science magazine, intrepid researchers at MIT, the University of Arizona, and Brookhaven National Laboratory in New York recently used high-speed x-ray imaging to provide the first look inside the bombardier beetle’s abdomen as it ejects its toxic spray. The beetle's defensive spray comes out in powerful pulses, like a machine gun from the butt, complete with smoke. 

Recorded at a rate of 2000 frames per second, the video shows how the beetles mix two chemicals in their abdomen to create benzoquinone, their defensive agent, and expel it from their body without doing any harm to themselves. The chemicals begin in separate chambers inside the beetle’s abdomen, then are released to mix together. As the chemicals combine in the beetle’s body, they heat up almost to the boiling point, creating pressure that expels the liquid out of the abdomen with heat, oxygen, and water vapor at a rate five times that of other insects that use benzoquinone as a defensive spray. 

The structure of the beetle’s blast-resistant butt may one day help to design systems to protect against larger explosions than those found inside a half-inch beetle, or possibly even a new kind of propulsion. Beetle-butt-inspired rockets, here we come. 

[h/t: Eurekalert]

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Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5
Climate Change Has Forced Mussels to Toughen Up
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Andreas Trepte via Wikimedia Commons // CC BY-SA 2.5

Researchers writing in the journal Science Advances say blue mussels are rapidly evolving stronger shells to protect themselves against rising acid levels in sea water.

Bivalves like mussels, clams, and oysters aren’t good swimmers, and they don’t have teeth. Their hard shells are often the only things standing between themselves and a sea of dangers.

But even those shells have been threatened lately, as pollution and climate change push the ocean's carbon dioxide to dangerous levels. Too much carbon dioxide interferes with a bivalve’s ability to calcify (or harden) its shell, leaving it completely vulnerable.

A team of German scientists wondered what, if anything, the bivalves were doing to cope. They studied two populations of blue mussels (Mytilus edulis): one in the Baltic Sea, and another in the brackish waters of the North Sea.

The researchers collected water samples and monitored the mussel colonies for three years. They analyzed the chemical content of the water and the mussels’ life cycles—tracking their growth, survival, and death.

The red line across this mussel larva shows the limits of its shell growth. Image credit: Thomsen et al. Sci. Adv. 2017

Analysis of all that data showed that the two groups were living very different lives. The Baltic was rapidly acidifying—but rather than rolling over and dying, Baltic mussels were armoring up. Over several generations, their shells grew harder.

Their cousins living in the relatively stable waters of the North Sea enjoyed a cushier existence. Their shells stayed pretty much the same. That may be the case for now, the researchers say, but it definitely leaves them vulnerable to higher carbon dioxide levels in the future.

Inspiring as the Baltic mussels’ defiance might be, the researchers note that it’s not a short-term solution. Tougher shells didn’t increase the mussels’ survival rate in acidified waters—at least, not yet.

"Future experiments need to be performed over multiple generations," the authors write, "to obtain a detailed understanding of the rate of adaptation and the underlying mechanisms to predict whether adaptation will enable marine organisms to overcome the constraints of ocean acidification."

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University of Adelaide
Scientists Find Potential Diabetes Drug in Platypus Venom
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University of Adelaide

The future of diabetes medicine may be duck-billed and web-footed. Australian researchers have found a compound in platypus venom (yes, venom) that balances blood sugar. The team published their results in the journal Scientific Reports.

So, about that venom. The platypus (Ornithorhynchus anatinus) may look placid and, frankly, kind of goofy, but come mating season, the weaponry comes out. Male platypuses competing for female attention wrestle their opponents to the ground and kick-stab them with the venom-tipped, talon-like spurs on their back legs. It’s not a pretty sight. But it is an interesting one, especially to researchers.

Animal venoms are incredible compounds with remarkable properties—and many of them make excellent medicine. Many people with diabetes are already familiar with one of them; the drug exenatide was originally found in the spit of the venomous gila monster. Exenatide works by mimicking the behavior of an insulin-producing natural compound called Glucagon-like peptide 1 (GLP-1). The fact that the lizard has both venom and insulin-making genes is not a coincidence; many animal venoms, including the gila monster’s, induce low blood sugar in their prey in order to immobilize them.

It’s a good strategy with one flaw: GLP-1 and compounds like it break down and stop working very quickly, and people who have trouble making insulin really need their drug to keep working.

With this issue in mind, Australian researchers turned their attention to our duck-billed friends. They knew that platypuses, like people, made GLP-1 in their guts, and that platypuses, like gila monsters, make venom. The real question was how these two compounds interacted within a platypus’s body.

The researchers used chemical and genetic analysis to identify the chemical compounds in the guts and spurs of platypuses and in the guts of their cousins, the echidnas.

They found something entirely new: a tougher, more resilient GLP-1, one that breaks down differently—and more slowly—than the compounds in gila monster spit. The authors say this uber-compound is the result of a "tug of war" between GLP-1’s two uses in the gut and in venom.

"This is an amazing example of how millions of years of evolution can shape molecules and optimise their function," co-lead author Frank Gutzner of the University of Adelaide said in a statement.

"These findings have the potential to inform diabetes treatment, one of our greatest health challenges, although exactly how we can convert this finding into a treatment will need to be the subject of future research."

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