US researchers from Stanford University have demonstrated a means to use short sections of DNA as rewritable data “bits” in living cells.
The technique uses two proteins adapted from viruses to “flip” the DNA bits.
Though it is at an early stage, the advance could help pave the way for computing and memory storage within biological systems.
The team reporting in Proceedings of the National Academy of Sciences says the tiny information storehouses may also be used to study cancer and aging.
The team, from Stanford University’s bioengineering department, has been trying for three years to fine-tune the biological recipe they use to change the bits’ value.
US researchers from Stanford University have demonstrated a means to use short sections of DNA as rewritable data "bits" in living cells
The bits comprise short sections of DNA that can, under the influence of two different proteins, be made to point in one of two directions within the chromosomes of the bacterium E. coli.
The data are then “read out” as the sections were designed to glow green or red when under illumination, depending on their orientation.
The two proteins, integrase and excisionase, were taken from a bacteriophage – a virus that infects bacteria. They are involved in the DNA modification process by which the DNA from a virus is incorporated into that of its host.
The trick was striking a balance between the two counteracting proteins in order to reliably switch the direction of the DNA section that acted as a bit.
After some 750 trials, the team struck on the right recipe of proteins, and now have their sights set on creating a full “byte” – eight bits – of DNA information that can be similarly manipulated.
The work is at the frontier of biological engineering, and senior author of the research Drew Endy said that applications of the approach are yet to come.
“I’m not even really concerned with the ways genetic data storage might be useful down the road, only in creating scalable and reliable biological bits as soon as possible,” Dr. Drew Endy said.
“Then we’ll put them in the hands of other scientists to show the world how they might be used.”
As the DNA sections maintained their logical value even as the bacteria doubled 90 times, one clear application would be in using the DNA bits as “reporter” bits on the proliferation of cells, for example in cancerous tissue.
But longer-term integrations of these computational components to achieve computing within biological systems are also on the researchers’ minds.
“One of the coolest places for computing is within biological systems,” Dr. Drew Endy said.
A bionic eye which is powered by light has been invented by scientists at Stanford University in California.
Implants currently used in patients need to be powered by a battery.
The new device, described in the journal Nature Photonics, uses a special pair of glasses to beam near infrared light into the eye.
This powers the implant and sends the information which could help a patient see.
Diseases such as age-related macular degeneration and retinal pigmentosa result in the death of cells which can detect light in the eye.
Eventually this leads to blindness.
A bionic eye which is powered by light has been invented by scientists at Stanford University in California
Retinal implants stimulate the nerves in the back of the eye, which has helped some patients to see.
Early results of a trial in the UK mean two men have gone from being totally blind to being able to perceive light and even some shapes.
However, as well as a fitting a chip behind the retina, a battery needs to be fitted behind the ear and a cable needs to join the two together.
The Stanford researchers say their method could be a step forward by “eliminating the need for complex electronics and wiring”.
A retinal implant, which works in a similar way to a solar panel, is fitted in the back of the eye.
A pair of glasses fitted with a video camera records what is happening before a patient’s eyes and fires beams of near infrared light on to the retinal chip.
The creates an electrical signal which is passed on to nerves.
Natural light is 1,000 times too weak to power the implant.
The researchers said: “Because the photovoltaic implant is thin and wireless, the surgical procedure is much simpler than in other retinal prosthetic approaches.
“Such a fully integrated wireless implant promises the restoration of useful vision to patients blinded by degenerative retinal diseases.”
The implant has not been tested in people, but has been shown to work in rats.
People’s willpower is obviously tested at Easter, when temptation comes in abundance and is often coated in chocolate, but a new book suggests that those who exercise greater self-control are those who have greater success in life.
British psychologist Roy Baumeister seems to cut a good example of self-regulation.
He is sharply dressed, immaculately groomed and his calm, well-punctuated speech betrays a quiet confidence.
“You might think that people with really strong self-control struggle through this grim existence, forcing themselves constantly to do the right thing,” Roy Baumeister says.
“But that’s not correct. What it seems is that people with good self-control stay out of trouble and minimize problems.”
In his book Willpower: Rediscovering our greatest strength, co-written by journalist John Tierney, Roy Baumeister claims that willpower – the ability to control impulses and thoughts, and persevere with tasks – is a limited resource which is depleted every time we successfully resist temptation.
Like a muscle it gets tired but like a muscle it can be exercised to make it stronger.
Roy Baumeister’s work builds on the famous marshmallow tests conducted at Stanford University 40 years ago, involving 300 four and five-year-olds.
They could have one marshmallow immediately or two marshmallows in 15 minutes time. They were left alone with the treat and observed.
A small number of the children took the treat immediately, most held back for about three minutes but about one third of the children managed to wait the full 15 minutes. Those who waited longer for the marshmallow seemed to do better in school, scored higher in exams and were more likely to go on to university. They also tended to be healthier and more popular.
In his book Willpower. Rediscovering our greatest strength Roy Baumeister claims that willpower is a limited resource which is depleted every time we successfully resist temptation
Roy Baumeister subscribes heavily to this theory and goes further to try to define what exactly willpower is.
He believes willpower is a physiological resource. Like energy it is a limited reserve that is depleted as the day goes on. But it can be exercised to make it stronger, much like a muscle.
Roy Baumeister coined the phrase “ego depletion” to describe his theory and ran a series of experiments to prove it.
The tests suggested that after a task that required the resistance of temptation, such as saying no to chocolate, people were less likely to perform a different task that required willpower, such as solving a puzzle.
But just like any other muscle, Roy Baumeister says willpower can be improved through training.
“We have taken adults who are already socialized and with a couple of weeks of exercises, we have improved their will power and self-control.”
Roy Baumeister asked people who were right-handed to use their left hand for every day exercises like brushing their teeth, controlling a computer mouse eating or opening a door.
He tested their level of ego depletion by asking them solve a series of anagrams. Before and after the two-week exercise, those who did the exercises seemed to show a marked improvement in anagram-solving.
“Habitual behaviour runs on automatic pilot,” says Roy Baumeister.
“To increase willpower, you need to override the automatic pilot and take charge with deliberate control.”
Getting people to sit up straight for two weeks, to speak only in full sentences or to avoid swearing seemed to have a similar effect. Roy Baumeister also found in other tests that willpower can be boosted by glucose. He called this “glucose resource theory”.
This has gained legitimacy among psychologists – glucose resource theory has been cited over 1,000 times in scientific papers. But it has also attracted some notable criticism.
“It’s almost like there is a self-fulfilling process here,” says Greg Walton, part of a team at Stanford University which has found evidence to debunk Roy Baumeister’s theory.
“The more that people believe that willpower is a limited physiological resource the easier it is to find ostensible evidence that that is the case.”
If Roy Baumeister’s resource theory is flawed, then what exactly is willpower? Michael Inzlicht, a psychologist at Toronto University argues for a more nuanced understanding of the processes behind self-control.
“It’s clear that consuming glucose can improve self-control,” he says.
“But we also know that being in a happy mood improves willpower. Being given a choice improves willpower and paying attention can improve willpower.”
“Glucose does seem to improve things, but this does not mean that glucose is the resource that underlies self-control.”
Michael Inzlicht believes glucose may have a psychological rather than a physical effect. But he doesn’t entirely disagree with Roy Baumeister’s muscle metaphor.
“I think willpower can be improved and exercising it seems like a promising way to do this,” he says.
Though he fully supports the theory of exercising to increase willpower, Michael Inzlicht believes Roy Baumeister’s assertions could be premature.
“This is promising, but more work is needed.”
