In a study published in the journal Nature Chemistry, the researchers showcased a purely chemical technique for gene assembly. It uses an efficient and rapid-acting chemical reaction called click chemistry that puts together multiple modified DNA fragments into a gene — a process called click DNA ligation.
Physicists already know that the rods at the back of the human eye are sensitive enough to light that they can be stimulated by a single photon. However, whether or not this sensitivity carries through the visual and cognitive systems of the brain and triggers perception is a different question entirely. Testing this query has demanded technology that was unavailable until recently. Now, physicists can produce pairs of photons using photon guns that work reliably and on demand.
The simple experiment to test the human ability to perceive a lone photon involves firing one into a human eye and determining if the subject observed it. Pairs of photons are important to the setup of this experiment because they ensure that the researchers can monitor when the photon gun was actually triggered each time. However, it’s not easy to get good results despite this simple structure, because human observers are unreliable and a statistically significant result requires a high number of trials.
Last month, researchers from the University of Vienna in Austria published findings from their own experiment, which was similar. Their version made itself unique by asking subjects to record the confidence of their observation. The subjects correctly observed single photons just over half of the time, at 51.6 percent. This led the team to conclude: “Humans can detect a single-photon incident on the cornea with a probability significantly above chance.”
However, researchers a the University of Illinois at Urbana-Champaign question have questioned that conclusion, saying that the data does not support it, and arguing that the experiment lacks sufficient statistical significance. The University of Illinois team has conducted its own research in human vision, so they have expertise in the field.
Our Powerful Senses
So, why does this matter? To begin with, the ability to detect such a minuscule amount of energy would define the physical limits of biology expressed in the workings of the human brain — a “machine” functioning in a wet environment plagued by constant noise. If our eyes could pick up on single photons, measuring around 10 to 19 Joules each, it would paint a compelling picture of the power of human biological senses.
Engineers and physicists aspire to achieve that kind of precision and sensitivity with their own machines in wet, warm environments, so modeling our machines after our own senses could allow us to reach higher goals. As we reveal our own sensory limits to ourselves, we can expect to see more impressive technological advances.
Humans have found a friend in yeast. The single-celled eukaryotes are used by humans for a wide variety of applications, such as making alcoholic beverages and baking, among others. Scientists are heading toward a breakthrough in bioengineering that could create synthetic organisms that will help make new kinds of drugs and fuels.
An international team of researchers has been able to devise a way to synthesize a large part of yeast’s genetic code. Prior to this announcement, the team had been able to completely synthesize one of yeast’s 16 chromosomes. Now, the team has published a series of papers in the journal Science showing that they have been able to add another five chromosomes, thus bringing their total to six. They say they’re on track to finish the remaining ten chromosomes to form a completely synthetic genome by the end of this year.
From Yeast to Human Genomes
While the scientific community remains leery of synthetic genome creation, many have united in praising this project’s work. In an article accompanying the research, Daniel Gibson, vice president of DNA technologies at Synthetic Genomics, stated, “This is really going to allow us to understand how to design cells from the bottom up that can be reprogrammed for many applications.”
Some of those “many applications” are what worry bioethicists, biologists, and environmentalists, among others. Todd Kuiken from North Carolina State University’s Genetic Engineering and Society Center compares the potential accidental or purposeful release of synthetic organisms to the introduction of invasive species. “You can think of it of like introducing an invasive species into a different environment. It will have some type of impact to the system.”
The yeast project is operating under conditions emphasizing safety as well as ethics. “This is a whole new era where we’re moving beyond little edits on single genes to being able to write whatever we want throughout the genome,” says George Church, a prominent Harvard University geneticist. “The goal is to be able to change it as radically as our understanding permits.”
The development of super materials is changing our world —from carbon nanotubes to graphene. Scientists and engineers the world over are continually developing newer ways to apply these materials. Researchers from the University of New South Wales (UNSW) in Australia are adding another material to this list, and it’s one of a biological origin.
UNSW researchers, in a paper published in the journal Scientific Reports, describe how it’s possible to craft advanced functional materials using “nature’s tissue weaving algorithms.” Specifically, they have engineered a “smart fabric” that mimics the sophisticated and complex properties of a bone tissue called periosteum. This tissue covers all the bones in the human body, except for the joints, and gives bones added strength to bear high impact loads. This resilience and durability come from periosteum’s complex collagen arrangements, elastin, and other structural proteins found within it.
The team mapped periosteum’s complex tissue architecture and modeled these in 3D. These computer models were used to scale up and produce fabric prototypes using a state-of-the-art computer-controlled Jacquard loom. “We then tested the feasibility of rendering periosteum’s natural tissue weaves using computer-aided design software,” said lead researcher Knothe Tate.
“The result is a series of textile swatch prototypes that mimic periosteum’s smart stress-strain properties,” Tate added. “We have also demonstrated the feasibility of using this technique to test other fibers to produce a whole range of new textiles.”
Weaving the Future of Joints
There was some challenge in retrieving a periosteum-based fiber from its 3D computer model into the weaving loom to become an actual material. “The challenge with using collagen and elastin is their fibers, that are too small to fit into the loom. So we used elastic material that mimics elastin and silk that mimics collagen,” Tate said.
With proof of concept tests completed, the team is now getting ready to produce fabric prototypes of this periosteum fabric. Patents for this super material are already pending in Australia, the United States, and in Europe. The materials’ applications are expected to range from advancing functioning medical materials, to improving safety and transport technology.
This material could even be used with ‘smart’ compression bandages that respond to the movement of patients with deep-vein thrombosis or similar ailments. It could help to develop protective suits that harden under high impact for extreme sports athletes, soldiers, or even astronauts. It could also be used for making safer steel belt radial tires.
While these applications are all great, the application intended by the UNSW researchers is more biological. “Our longer term goal is to weave biological tissues – essentially human body parts – in the lab to replace and repair our failing joints that reflect the biology, architecture and mechanical properties of the periosteum,” lead author Joanna Ng explained. The team is currently working towards this next stage, hoping to unlock the potential of this super material.