DNA is useful for many things, starting with that whole molecule-of-heredity thing and moving on to identifying murderers and rapists while exonerating the innocent. These are merely the tip of the iceberg, it turns out, when it comes to DNA’s talents: the double helix also makes an excellent origami material.

As scientists led by chemist Jørgen Kjems of Denmark’s Aarhus University report today in Nature, strands of DNA can be stitched together to form three-dimensional boxes measuring 42 by 36 by 36 nanometers. The key to making this work is that DNA is formed of molecules that recognize and bind with one another. Starting from this premise, Kjems and his colleagues wrote a computer program that determined which particular sequences of those molecules were needed to make a six-sided, hollow box—including an openable lid. The program spit out the answer: 220 snippets of DNA that will attach to the long piece of DNA from a virus called a bacteriophage.

All that was left for the scientists to do was buy the specified snippets and mix them with the long viral DNA. The snippets bent and turned each strand until it made a wall, and then attached the six walls into a box. In just a couple of hours the snippets had induced the self-assembly of billions of boxes. “It's amazing that it works,” Kjems told Nature. “It’s like taking your car apart, putting the nuts and bolts into a bag, shaking it, and the car builds itself.”

For their next clever move, the scientists attached a short stretch of DNA to one side of the box which was the chemical mate of another short stretch. When the second bit of DNA was added to the solution containing the boxes, it acted like a zipper tongue, unstitching the link between one wall and its neighbor so that the wall opened like a boxtop.

The zippable lid means that the DNA origami box might be used to transport drug molecules to a target in the body, releasing its contents only when the DNA un-zipper is added. Nature has a nice write-up in lay language here.

It's bird week at Lab Notes, what with yesterday's blue tits and now this:

Just because one cockatoo named Snowball can bob and sway to the Backstreet Boys, as millions of YouTube fans know, doesn’t mean birds can sense musical beat and rhythm. As scientists are fond of saying, the plural of anecdote is not data. In this case, it was possible that Snowball had learned a specific routine that happened to go with a song, and not that he could dance in time to music.

But when neuroscientist Aniruddh Patel of The Neurosciences Institute in La Jolla tested the bird, as he and colleagues report online in Current Biology, electronically altering the beat and tempo of Snowball’s favorite song, they found that the bird adjusted his bobbing and swaying to the beat, “spontaneously adjust[ing] the tempo of its rhythmic movements to stay synchronized with the beat.” It’s the first evidence that an animal other than humans can move in time to a musical beat. “If the music speeds up or slows down across a wide range, he adjusts the tempo of his dancing,” said Patel.

None of humankind’s close primate relatives do that, and despite some pet owners’ beliefs, there is no good evidence that dogs and cats do it reliably either. The finding that parrots can (as another study in the same journal also reports) suggests that the ability is related to vocal learning or mimicry, perhaps using the same neural circuitry: after all, complex vocal learning and dancing to a beat both require a strong association between auditory and motor circuits in the brain.

To see for yourself, go here.

Everyone knows that females are programmed to be monogamous and males to be promiscuous, since a female is limited in how many offspring she can have in any period of time but males, by spreading their seed far and wide, have practically limitless opportunities for paternity. There is therefore little adaptive advantage to a female’s promiscuity, but lots of evolutionary pressure for males to mate with anything that will stand still, goes the dogma. Except that someone forgot to tell the blue tits.

These female birds often mate with males other than their regular partners, scientists have long known, but the reason has been a bit of a mystery. A new study suggests that the old favorite explanation—that these “extra-pair” copulations (as in, outside the pair bond) produce genetically-superior offspring—might not be the right explanation. Instead, scientists report online in Current Biology, when female blue tits stray, producing broods of chicks that have different fathers, the offspring of fathers other than mom’s regular mate may get a head start in life, suggests Michael Magrath of University of Groningen, The Netherlands.

Blue-tit eggs fertilized by males other than the regular mate tend to be laid before eggs fathered by the mate, they report, and to hatch earlier, too: almost 75 percent of the extra-pair eggs were laid in the first half of the clutch. As a general rule, “earlier hatching chicks perform better than later hatching siblings,” notes Magrath, because by hatching first they get an edge in competition for food. In fact, this early emergence accounts for almost all the differences between the offspring of mom’s regular mate and those of her extracurricular friend, he says, “indicating that non-genetic laying order effects largely accounted for the observed superiority of extra-pair offspring.”

What remains unknown is why Lothario’s eggs hatch first. But if extra-pair matings produce chicks that are first out of the gate, it may be a reflection of the ultimate reason for female promiscuity: as insurance against the possibility that her regular mate is infertile. By seeking other fathers for her chicks, the female blue tit can make sure that all her eggs are fertilized even if her mate is shooting blanks. “Because birds can store sperm for an extended period in specialized storage tubules, females may have little need to continue engaging in extra-pair copulation after laying starts, and this would rather neatly explain the decline in extra-pair offspring that we observed with laying order,” Magrath said.

When I wrote a year ago about surprising new evidence that Botox and other drugs containing the neurotoxin botulinum could travel from the site of injection to the brain, it wasn't clear whether this posed a threat to patients (the study I described was done on lab animals). But yesterday the Food and Drug Administration announced that the risk was all too real: it will now require Botox, Myobloc and the other botulinum drugs to carry a black box warning—the strongest there is—alerting doctors and patients that the drug can spread to distant parts of the body, posing serious risks such as trouble breathing and swallowing. The FDA is also requiring manufacturers to send doctors a letter warning of the risk.

The action comes in response to a petition from Public Citizen, which in 2008 asked FDA to require both a black box and the warning letters. If I’d had to guess, I would have predicted that FDA would have limited the warnings to non-cosmetic uses of the drugs, since that’s where most of the problems had occurred (botulinum is used to treat cervical dystonia, eyelid spasms and a few other medical conditions in addition to frown lines), especially in unapproved uses such a limb spasticity in kids with cerebral palsy.

But the agency said it found 225 cases in which the drug had migrated beyond the injection site. That was alarming enough to justify the black-box decision, even on cosmetic Botox. As FDA put it, "there is insufficient information to fully characterize the safety profile and potential risk factors for spread of botulinum toxin at this time, given that the mechanism by which spread may occur has not been confirmed. . . . Based on available information, it is not possible to precisely predict the role of injection site, injection technique, or dose in the spread of toxin or severity of the event. Therefore, we are seeking safety labeling changes for the both the dermatologic and neurologic indications."