Tyrannosaurus rex was the most terrifying animal that ever lived, apart from its silly little arms, which were no use for anything. Now it seems this giant predator did not need proper arms, because its head and neck were so powerful.

Tyrannosaurs, the family of big predatory dinosaurs that includes T. rex, had necks that were similar to those of modern birds. So by studying how birds feed, of the University of Wisconsin–La Crosse and his colleagues were able to reconstruct how T. rex went about making a kill.

“We looked at a number of raptors and documented their behaviour,” says Snively. “There is a strong possibility that the tyrannosaurs behaved in the same way.”

Snively placed electrodes on the skin of a dozen birds from 10 different species, ranging from domestic chickens to bald eagles. That allowed him to identify the precise muscle movements underlying each stage of feeding.

Shake and snap

Snively found that the birds often raised their heads and fixed their vision on the prey before lowering their heads to attack. T. rex had most of the same muscles, suggesting it could perform the same movements. That would also include raising its head, thrusting it upwards and pulling back with its legs once it has taken a bite.

Many of the birds also shook their necks, and the main muscle involved was found in the necks of tyrannosaurs. “The shaking motion is the same as when a dog shakes off water,” says Snively. “We think that the dinosaur would have used this motion to dislodge meat from a carcass.”

Their powerful necks could explain why tyrannosaurs had such small arms, says Snively. “Tyrannosaurs didn’t need big arms to hunt, because their powerful bites and hyper-bulldog necks did the job,” he says. “From the shoulders forward, T. rex was like a whole killer whale: just bite, shake and twist.”

Tyrannosaur necks are also similar to crocodile necks. “We can think of them as striking like a bird, and shake-feeding like a crocodile,” says Snively.

The results are promising, says of Queen Mary University of London. “We need to be careful not to overly rely on these as analogies, but in at least some ways, some animals like tyrannosaurs that are relatively distant from birds are still very bird-like.”

Journal reference:

“They could potentially carry out complex programs that could be used to diagnose or treat diseases with unprecedented sophistication,” says Daniel Levner, a bioengineer at the Wyss Institute at Harvard University.

Levner and his colleagues made the nanobots by exploiting the properties of DNA. When it meets a certain kind of protein, DNA unravels into two strands. Make the strands with particular DNA sequences and they will unravel on contact with particular molecules – say, those on a diseased cell. And if the DNA has drugs in its folds, it releases them when it uncurls.

The team has injected various kinds of nanobots into cockroaches and says the accuracy and control of the nanobots is equivalent to a computer system (Nature Nanotechnology, ).

“This is the first time that biological therapy has been able to match how a computer processor works,” says co-author Ido Bachelet of Bar Ilan University in Ramat-Gan, Israel. The number of nanobots in the study makes it particularly promising, he says. “If you reach a certain threshold of capability, you can perform any kind of computation. In this case, we have gone past that threshold.”

The team says it should be possible to scale up the computing power in the cockroach to that of an 8-bit computer, equivalent to a Commodore 64 or Atari 800 from the 1980s.

The robots could be useful in cancer treatments, because they can target specific cells. However, foreign objects in the body trigger an immune response. Bachelet is confident that they can make the robots stable enough to survive this. “There is no reason why preliminary trials on humans can’t start within five years,” he says.

This article appeared in print under the headline “DNA nanobots deliver drugs in cockroaches”

It’s a computer – inside a cockroach. Nano-sized entities made of DNA that are able to perform the same kind of logic operations as a silicon-based computer have been introduced into a living animal.

The DNA computers – known as origami robots because they work by folding and unfolding strands of DNA – travel around the insect’s body and interact with each other, as well as the insect’s cells. When they uncurl, they can dispense drugs carried in their folds.

“DNA nanorobots could potentially carry out complex programs that could one day be used to diagnose or treat diseases with unprecedented sophistication,” says , a bioengineer at the Wyss Institute at Harvard University.

Levner was part of a team that made the nanobots by exploiting the binding properties of DNA. When it meets a certain kind of protein, DNA unravels into two complementary strands. By creating particular sequences, the strands can be made to unravel on contact with specific molecules – say, those on a diseased cell. When the molecule unravels, out drops the package wrapped inside.

A bug’s life

The team has now injected various kinds of nanobots into cockroaches. Because the nanobots are labelled with fluorescent markers, the researchers can follow them and analyse how different robot combinations affect where substances are delivered. The team says the accuracy of delivery and control of the nanobots is equivalent to a computer system.

“This is the first time that biological therapy has been able to match how a computer processor works,” says co-author of the Institute of Nanotechnology and Advanced Materials at Bar Ilan University.

“Unlike electronic devices, which are suitable for our watches, our cars or phones, we can use these robots in life domains, like a living cockroach,” says of the National Center for Biotechnology in Madrid, Spain. “This opens the door for environmental or health applications.”

DNA has already been used for storing large amounts of information and circuits for amplifying chemical signals, but these applications are rudimentary compared with the potential benefits of the origami robots.

Commodore cockroach

The number of nanobots in the study – more than in previous experiments – makes it particularly promising, says Bachelet. “The higher the number of robots present, the more complex the decisions and actions that can be achieved. If you reach a certain threshold of capability, you can perform any kind of computation. In this case, we have gone past that threshold,” he says.

The team says it should be possible to scale up the computing power in the cockroach to that of an 8-bit computer, equivalent to a Commodore 64 or Atari 800 from the 1980s. Goni-Moreno agrees that this is feasible. “The mechanism seems easy to scale up so the complexity of the computations will soon become higher,” he says.

An obvious benefit of this technology would be cancer treatments, because these must be cell-specific and current treatments are not well-targeted. But a treatment like this in mammals must overcome the immune response triggered when a foreign object enters the body.

Bachelet is confident that the team can enhance the robots’ stability so that they can survive in mammals. “There is no reason why preliminary trials on humans can’t start within five years,” he says.

Journal reference: Nature Nanotechnology,

The UK has suffered an unusually severe smog over the last two days. The as a result.

żěè¶ĚĘÓƵ examines how dangerous the spike in pollution is, and what is going to happen to the UK’s air in the future.

See graph: “Is the UK’s air getting cleaner or dirtier?“

What has happened?
A mixture of particles from Europe and the Sahara desert shrouded England in smog yesterday, with London, parts of the south-east and the Midlands all affected.

In some places the severity of air pollution reached 9 or 10 on used by the UK’s Department for the Environment, Farming and Rural Affairs. The smog is expected to subside to very low levels by the end of the week.

How harmful is it going to be?
It is hard to say how many people will be harmed by the spike in pollution.

There are two types of particle that pose a threat to people’s health: those smaller than 10 micrometres, known as PM10, and those smaller than 2.5 micrometres across, or PM2.5.

The PM2.5 are more dangerous, says of King’s College London. “PM2.5 is small enough to get deep down into the respiratory tract and be absorbed.” This can exacerbate asthma and other respiratory complaints, and is also linked to deaths from heart attacks.

Williams estimates that there are currently about 29,000 premature deaths a year in the UK because of high pollution levels. He says the main risk comes from sustained exposure in the long-term, not short-term spikes like this one. “If the average doesn’t go down, the bulk of health implications won’t improve.”

Is this normal for the UK?
Although the levels in London are well above the local average, this spike in pollutants is nothing out of the ordinary, says Williams. “We have seen episodes like this before.”

They are also not unusual by European standards, says Williams. “Levels are typical of a large European city like Rome or Paris.”

People in other cities have it far worse on a regular basis. “On a global scale London is actually relatively clean, with pollutant levels nowhere near those in Beijing or Delhi,” says Williams.

The UK’s average air quality has actually improved since 2000. The proportion of the population exposed to harmful levels of PM2.5 – defined by the World Health Organization as – has been falling (see “Is the UK’s air getting cleaner or dirtier?“).

What’s going to happen in the future?
There is every chance that air quality in the UK will improve over the next 10 years, as most European states are working to reduce the amount of fossil fuels they burn.

The fly in the ointment is that climate change will also increase temperatures. This affects atmospheric chemistry, leading to more frequent summer smogs. “There is a balance,” says Williams. “If emissions stay the same, summer smog will increase a lot because of temperatures rising.” The question is whether Europe will cut its emissions enough to offset this.

The other issue is that Europe is getting ever more energy by burning biomass such as wood. This is encouraged because it limits climate change, but it has a downside. “It actually emits large amounts of particles, which contribute to air pollution,” says Williams. “European countries in particular burn a lot of wood.”