A protein is a chain of amino acids held together by what are called peptide bonds. On their own, those bonds are extremely stable; they're estimated to have a half-life of several hundred years. But in Earth's environment, most proteins don't last nearly that long. That's because organisms have evolved a handful of ways to catalyze the break-up of peptide bonds, which have diversified into countless specialized protein-digesting enzymes. Proteases are everywhere and generally make short work of any proteins that find their way into the environment.

Now, researchers have basically short-circuited the diversification process, using AI-based protein design tools to take the catalytic core of two types of protease and replace the entire rest of the protein. The resulting enzymes could be tuned to cut specific proteins in half, and the researchers demonstrated their effectiveness by using them to cut proteins associated with neurological diseases.

Cutting proteins

The basic peptide bond isn't especially interesting-looking—it's what you get when you link an amino group to an acid, releasing a water molecule in the process. As their name implies, amino acids have both an amino and an acid group, allowing them to form peptide bonds on two sides of the amino acid. This is critical for building up the long chains found in proteins. (The amino acids also have side chains with distinctive chemistry, which gives a backbone specific properties.)

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Honey bees are known to leave their stingers embedded in tender flesh once they sting you and fly away. Scientists have now determined that the stinger is able to continue pumping venom into its unfortunate victim even after the bee flies away, thanks to a unique double-piston pump-like mechanism, according to a new paper published in the Proceedings of the National Academy of Sciences.

Different species have evolved different mechanisms for delivering venom, which involves piercing the skin and then pumping venom from a gland or reservoir. Spiders, for instance, have muscles surrounding their venom glands, which contract and eject venom through hollow fangs. Bees, wasps, and ants deliver venom via their stingers, either by contracting muscles around the venom reservoir or through stiff elements called lancets working together to pump venom.

Honey bees (Apis mellifera) add a unique feature: Worker bees fly away after inserting their stingers in the target, leaving the stinger behind. The stinger continues to penetrate the tissue and pump venom on its own, a rare phenomenon known as autotomy. A honey bee's stinger has three main interlocking elements that form the venom canal: a stylet that widens to form the main pumping chamber and two sharp-tipped lancets that slide back and forth, piercing the tissue and pumping venom into the target. But the precise mechanism by which the pumping action is achieved has never been directly observed.

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Over decades of research, scientists have built up a partial picture of what specialized cells within the brain and spinal cord do. By studying how the brain develops, they could identify genes that were active in different populations of neurons and where in the brain those neurons resided. In some cases, these genes could then be used to genetically delete the neurons, allowing us to get some indication of what they might be doing, building on the information we've obtained from studies of brains with damaged regions.

But this approach has its limits. The brain is flexible enough to potentially adapt to the loss of some cells, and their loss early in development may alter the development of any neurons they would have normally formed connections with. It would be far more informative to activate and shut down the neurons in an otherwise intact brain.

Today's Nobel Prize in Physiology or Medicine rewards three people—Karl Deisseroth, Peter Hegemann and Georg Nagel—who developed our ability to do precisely that. Starting from studies of single-celled algae that are attracted to light, these and many other researchers built an entire field of study that we now call optogenetics: using light to alter the behavior of nerve cells marked by the activity of individual genes.

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Most implants like pacemakers and insulin pumps work in isolation. To help them coordinate with each other, a team of Georgia Tech researchers built a networking system that sends signals through body tissue instead of antennas and radio waves.

Radio problems

Implants that communicate today mostly rely on radio protocols like Bluetooth Low Energy or near-field communication (NFC). Both are a poor fit for in-body data transfer, says Alex Abramson, a Georgia Tech engineer and co-author of the new study.

The first problem is power. “If you want an implant to remain in an active state such that it can respond within milliseconds, it's very difficult to do that with the Bluetooth system,” Abramson said. According to the paper, Bluetooth components, when they’re activated, can cut an implant's battery life by up to 90 percent.

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AI-based tools seem to be causing security threats on a nearly daily basis, in part because we've been slow to recognize potential threats. One area where we seem to be ahead of the game, however, is in biosecurity.

As with most things biological, utility goes hand in hand with threats. We've developed increasingly sophisticated tools for designing proteins and seen some major successes, such as AI-designed enzymes that can digest plastics or block venom proteins. But these same tools could be used to make toxins or alter the behavior of viral proteins.

And the software we use to identify DNA sequences that encode potentially threatening proteins doesn't pick out AI-designed proteins, since nobody has characterized them well enough to know that they're threats. Nearly a year after that risk was flagged, it still wasn't clear what anyone could do about it.

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Old-fashioned striped barbershop poles turn in place on a vertical axis, but humans typically perceive the stripes moving upward rather than turning with the pole. It's a well-known visual illusion arising from processing biases in human vision. According to a new paper published in the journal Nature, a similar effect could explain how butterflies often evade predatory birds: Their flight patterns and wing patterns combine to make it hard for predators to accurately gauge speed and direction.

"The stripes and spots on many butterflies’ wings interfere with the way visual systems try to guess the direction and speed of moving things, boosting false motion cues while hiding the butterfly's true heading," said co-author George Hancock of the University of Exeter in Cornwall. "The illusions interfere with the predator’s most basic visual targeting system and disrupt the final ‘ballistic attack’ in the tens of milliseconds when it commits to grabbing its prey, with no time to change course. As a result, birds and other predators will often simply miss."

Butterfly wings have long fascinated scientists, ever since the first documentation of the growth of said wings back in 1938. By 2021, researchers at MIT had captured on video the unique structural growth of butterfly wings—continuously, as a butterfly develops inside its chrysalis—for the very first time. Butterfly wings are an example of structural color in nature: the bright iridescent colors don’t come from pigment molecules but from what physicists call photonic crystals. The scales of chitin (a polysaccharide common to insects) are arranged like roof tiles. Essentially, they form a diffraction grating, except photonic crystals only produce certain colors, or wavelengths, of light, while a diffraction grating will produce the entire spectrum.

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