Explainer: what is a gene drive and how could it wipe out malaria?

Michael Bonsall, University of Oxford

Our understanding of the natural world is now so great we can manipulate the DNA blueprints for any living thing on Earth. We can replace genes for traits we don’t like with others we prefer and even add genes that don’t occur naturally in an organism. Over the last few years, scientists have developed several methods for editing genes in this way and excitement over one in particular, the CRISPR-Cas9 system, has reached fever pitch.

We have also developed a way to introduce these gene changes to an entire population of a species. This “gene drive” process has most recently been used to alter the DNA of small groups of mosquitoes so that they no longer carry the malaria parasite, raising the possibility of eliminating the disease altogether. But meddling with nature in this way carries huge implications that need careful consideration.

Gene editing

Gene-editing techniques involving cutting genes at specific sites in the DNA of an embryo in order to disrupt those genes’ function or insert other genes. For instance, the CRISPR-Cas9 system uses enzymes that can cut specific gene sequences from DNA, guided by a similar molecule known as RNA. Natural gene repair mechanisms then kick in and can be used to disrupt the function of the original gene or replace it with a completely different one.

CRISPR systems actually aren’t new – they have existed in nature for millions of years. Bacteria use them to fend off viral infections by adding part of the virus’s DNA to their own. So why all the fuss? CRISPR-Cas9 makes artifical gene-editing much easier and cheaper, enabling scientist to target specific bits of DNA. By comparison, another method known as TALENS requires the construction of complex proteins. As a result, CRISPR gene-editing is heralding advances in biomedicine such as cancer treatments and protecting individuals from infections

But there are other ways gene-editing has the potential to help in the fight against infectious diseases. Very recently, CRISPR methods have been used to make mosquitoes resistant to malaria infections and coupled with a “chain reaction” to drive this gene modification (the resistance to malaria parasite) through the population.

Gene drive

This process is referred to as a “gene drive”, and again is not new: nature spreads evolutionary changes through a population all the time. It doesn’t mean changing the DNA of all living individuals in a population. Instead it’s about ensuring a specific genotype (a certain version of a gene) is passed on to the descendants of modified individuals.

A sexually reproducing organism usually has a 50% chance of inheriting a specific genotype from one of its parents. Using a gene drive can bias the inheritance pattern to increase that chance to nearly 100%, ensuring almost all descendants possess the genotype. As those descendants mate and produce their own offspring, the proportion of organisms with the genotype increases until it can be found in the entire population.

Gene warfare on malaria.
Shutterstock

The idea that you can “replace” a population’s genotype is particularly appealing when that population is responsible for spreading disease, as mosquitoes are with malaria. Malaria is preventable and curable but still kills over 400,000 people each year.

The potential for using a gene drive to engineer insects (particularly mosquitoes) was discovered in the 1960s. But the advent of CRISPR’s cheap and easy gene-editing puts this research onto a whole new footing. Researchers at the University of California, Irvine, recently published a proof-of-princple study demonstrating the techniques can alter a population of the main type of mosquito that carries malaria in urban India, Anopheles stephensi.

Putting into practice

The longer term aim, in this instance, might be to release a persistent, modified mosquito into the environment to assist in the control a public health problem. This would be an area-wide release programme to compliment existing control interventions that would require case-by-case assessment of all the cost and benefits. For example, mathematical modelling would be needed to work out how many modified mosquitoes to release, how long it would take for the mosquito population to be clearly affected and how long it would take to impact public health.

One obstacle to the practical use of gene-drives is the need for relevant regulations, or at least the application of existing laws on genetic modifications. Gene-drive technologies are still some way off from the necessary environmental risk assessments for field trials and releases that would sufficiently scrutinise the risks to the environment and/or human health. These sorts of CRISPR-based modifications might even need a whole new set of regulatory structures that require a fuller debate about novel biotechnological advances.

Rapidly targeting genome modifications has the power to advance many aspects of basic and translational biomedical sciences. The potential benefits to reducing the impact of infectious disease and genetic disorders, including cancers, and improving the way the immune system works are huge. But the technology isn’t without pitfalls.

CRISPR systems rely on a guide molecule to make sure the DNA sequence is cut in exactly the right place. Getting this wrong will probably cause damage to non-target genes that could harm the organism. And just because we can edit the DNA within a species doesn’t mean we should. We need strong leadership at all levels – ethical, scientific, political – and appropriate regulations to ensure these new technologies can prosper without unintended consequences.

The Conversation

Michael Bonsall, Professor of Mathematical Biology, University of Oxford

This article was originally published on The Conversation. Read the original article.

Featured Image Credit: Christoph Bock (Max Planck Institute for Informatics)/flickr CC BY-SA 3.0

Cloaking Process Will Make Solar Cells More Efficient [Video]

A solar cell is basically a semiconductor, which converts sunlight into electricity, sandwiched between metal contacts that carry the electrical current.

But this widely used design has a flaw: The critical but shiny metal on top of the cell reflects sunlight away from the semiconductor where electricity is produced, reducing the cell’s efficiency.

Now, scientists have discovered how to hide the reflective upper contact and funnel light directly to the semiconductor below. The findings could lead to a new paradigm in the design and fabrication of solar cells, researchers say.

“Using nanotechnology, we have developed a novel way to make the upper metal contact nearly invisible to incoming light,” says study lead author Vijay Narasimhan, who conducted the work as a graduate student at Stanford University. “Our new technique could significantly improve the efficiency and thereby lower the cost of solar cells.”

In most solar cells, the upper contact consists of a metal wire grid that carries electricity to or from the device. But these wires also act like a mirror and prevent sunlight from reaching the semiconductor, which is usually made of silicon.

“The more metal you have on the surface, the more light you block,” says study coauthor Yi Cui, associate professor of materials science and engineering. “That light is then lost and cannot be converted to electricity.”

Metal contacts, therefore, face a seemingly irreconcilable tradeoff between electrical conductivity and optical transparency, Narasimhan says. “But the nanostructure we created eliminates that tradeoff.”

For the study, published in the journal ACS Nano, researchers placed a 16-nanometer-thick film of gold conducting metal on a flat sheet of silicon. The gold film was riddled with an array of nanosized square holes, but to the eye, the surface looked like a shiny, gold mirror.

Optical analysis revealed that the perforated gold film covered 65 percent of the silicon surface and reflected, on average, 50 percent of the incoming light. The scientists reasoned that if they could somehow hide the reflective gold film, more light would reach the silicon semiconductor below.

LIKE A COLANDER IN THE SINK

The solution: Create nanosized pillars of silicon that “tower” above the gold film and redirect the sunlight before it hits the metallic surface. The idea turned out to be a one-step chemical process.

“We immersed the silicon and the perforated gold film together in a solution of hydrofluoric acid and hydrogen peroxide,” says graduate student and study coauthor Thomas Hymel. “The gold film immediately began sinking into the silicon substrate, and silicon nanopillars began popping up through the holes in the film.”

Within seconds, the silicon pillars grew to a height of 330 nanometers, transforming the shiny gold surface to a dark red. This dramatic color change was a clear indication that the metal was no longer reflecting light.

“As soon as the silicon nanopillars began to emerge, they started funneling light around the metal grid and into the silicon substrate underneath,” says Narasimhan, who compares the array to a colander in a kitchen sink.

“When you turn on the faucet, not all of the water makes it through the holes in the colander. But if you were to put a tiny funnel on top of each hole, most of the water would flow straight through with no problem. That’s essentially what our structure does: The nanopillars act as funnels that capture light and guide it into the silicon substrate through the holes in the metal grid.”

The researchers then optimized the design through a series of simulations and experiments.

“Solar cells are typically shaded by metal wires that cover 5 to 10 percent of the top surface,” Narasimhan says. “In our best design, nearly two-thirds of the surface can be covered with metal, yet the reflection loss is only 3 percent. Having that much metal could increase conductivity and make the cell far more efficient at converting light to electricity.”

For example, this technology could boost the efficiency of a conventional solar cell from 20 percent to 22 percent, a significant increase, he says. The researchers plan to test the design on a working solar cell and assess its performance in real-world conditions.

Besides gold, the nanopillar architecture will  also work with contacts made of silver, platinum, nickel, and other metals, says graduate student and coauthor Ruby Lai.

Watch the video on the next page to hear about this amazing new technology directly from the inventor…

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The Newest Mosquito-borne Disease Is Scarier Than First Thought

Chikungunya means “to become contorted” or “that which is bent up” in Kimakonde, the language of the Makonde people in Tanzania and Mozambique. It refers to the bent or stooped stature of joint pain sufferers. And it also is the name of a mosquito-borne virus that can cause chronic symptoms like that in those who get infected with it.  In 2005, there was a year and a half epidemic of chikungunya on Reunion Island, near Madagascar, that may have been caused by residents collecting and storing water in open containers outside due to a drought.

And now it may be coming soon to a stagnant pond near you.

An informative, if somewhat frightening, article on the NPR website lays out the details:

Chikungunya starts with fevers and aches, like malaria and other mosquito-borne diseases. What distinguishes the virus is that is also brings with it debilitating joint pain. The pain usually dwindles over the course of a few weeks, though it can leave some people with chronic arthritis.

But a new study in the journal Neurology, shows some people with chikungunya developed encephalitis, an infection of the brain that can lead to memory problems, dementia and even death. The study was conducted at the Central University Hospital in Saint Pierre, Reunion Island, off Madagascar.

Dr. Patrick Gerardin says an epidemic on Reunion Island affected some 300,000 people.

Gerardin and his colleagues followed up with patients three years after the outbreak. Looking at a sample of about 300 people, they found 57 had central nervous system disease, including 24 who had encephalitis.

“As it spreads across the world, we’re realizing that it’s not so benign” says Dr. Desiree LaBeaud, a professor of pediatrics who studies the chikungunya virus at the Stanford University School of Medicine.

Several years after the Reunion Island outbreak, chikungunya was discovered in the Americas — first in the Caribbean in 2013 and then Mexico and Florida in 2014. The summer it was discovered in Florida, about a dozen people got the virus from mosquitoes in the southeastern part of the state.

Right now there is no approved vaccine for chikungunya, but one has been designed by researchers and is being tested. People who get infected with the virus do develop immunity to it, but as the study found, almost 20% end up with chronic issues, including encephalitis, so finding an effective vaccine is imperative.

Read the excellent article on the NPR website for more details.

 

Source: NPR.org – “Chikungunya, A Mosquito-Borne Virus, Might Be Scarier Than We Thought

Featured Image Credit: David Scharf/Science Source

Exoplanet Finding is Hard, So Researchers Invented This Amazing Instrument

What’s most difficult in finding Earth-like exoplanets that may support life is pretty much what you’d guess – the brightness of distant stars overwhelms the ability to see planets of this size. Existing and planned space and ground-based telescopes use indirect methods to detect planets around other stars, and there are many limitations to these indirect methods, especially when it comes to smaller planets.

So, scientists at NASA’s Goddard Space Flight Center designed a ground-breaking instrument in order to be able to directly detect exoplanets. A fascinating article on the NASA website explains:

A potentially revolutionary instrument now being developed to first find Earth-like planets in other solar systems and then study their atmospheres to identify chemical signatures of life has just passed another technological hurdle that makes it an even stronger contender for a future astrophysics mission.

The instrument, called the Visible Nulling Coronagraph (VNC), combines an interferometer with a coronagraph — in itself a first. It’s well on its way to demonstrating operations over a broader spectral range, including the ultraviolet, visible, and near-infrared bands, said Brian Hicks, a fellow with NASA’s Postdoctoral Program who is working with VNC Principal Investigators Rick Lyon and Mark Clampin, who are scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

“The VNC is demonstrating the spectral range needed for planet characterization,” Hicks said. “It will be more sensitive for finding fainter planets. It also will enable spectroscopy, which is what NASA will need to study the atmospheres of exoplanets to identify signatures of water, oxygen, carbon dioxide, methane, and ozone — the chemistry we associate with habitability for life as we know it.”

Currently, the Kepler Observatory uses indirect means to detect exoplanets, as will the James Webb Space Telescope and the Transiting Exoplanet Survey Satellite in the future.

The next logical step is direct detection using a next-generation space observatory equipped with highly sophisticated instruments, including a coronagraph or occulting star shade that would block starlight and allow the observatory to directly image faint Earth-like exoplanets.

The VNC, which Clampin and Lyon started developing nearly six years ago, is ideally suited to this task. Its pupil-based technique for separating star from planet light is naturally compatible with segmented or arbitrarily shaped telescope mirrors, similar to the one that will form the heart of the Webb Observatory. Such a mirror folds up for launch and then unfolds once the observatory reaches its orbital destination.

In this image taken in 2012, Rick Lyon (foreground), Udayan Mallik (left), and Sigma Space’s Pete Petrone (right) monitored the progress of wavefront control using the early version of the Visible Nulling Coronagraph that at the time was operating inside a vacuum tank. This version of the instrument proved the VNC concept. Credits: NASA/C. Gunn
In this image taken in 2012, Rick Lyon (foreground), Udayan Mallik (left), and Sigma Space’s Pete Petrone (right) monitored the progress of wavefront control using the early version of the Visible Nulling Coronagraph that at the time was operating inside a vacuum tank. This version of the instrument proved the VNC concept.
Credits: NASA/C. Gunn

 

The article details how the VNC uses very innovative technology to split the light gathered by the telescope it is integrated with into two channels, called the light and the dark channels. Starlight goes to the light channel, and planet light goes to the dark channel. Then the dark channel is then analyzed by a spectrograph and an imager to determine the physical properties of any planet that is found.

Check out the excellent and detailed article on the NASA website which goes into much deeper technical detail on how this revolutionary new exoplanet detecting technology will get the job done.

Source: NASA.gov – “Innovative Planet-Finding Technology Passes Another Hurdle

Featured Image Credit: NASA/W. Hrybyk

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Want to do something good for your health? Try being generous

Ashley Whillans, University of British Columbia

Every day, we are confronted with choices about how to spend our money. Whether it’s thinking about picking up the tab at a group lunch or when a charity calls asking for a donation, we are faced with the decision to behave generously or not.

Research suggests that spending money on others can improve happiness, but can it also improve your physical health?

There is some evidence that donating time can improve physical health, but no one has looked at whether donating money has the same effect.

So my colleagues and I at the University of British Columbia decided to conduct an experiment to find out if spending money on others could lower blood pressure, which will be published in the journal Health Psychology in December.

Helping out.
ccbarr/Flickr, CC BY-SA

Helpful people might be healthier

A 1999 study examining whether volunteering had an effect on mortality provided initial evidence for an association between helping others and physical health. In the study, adults age 55 and older reported how many organizations they helped, how many hours they spent volunteering, and then underwent a physical exam.

Researchers controlled for several factors, including how healthy participants were when the study began and their available social support. After five years the adults who reported providing more help to others were 44% more likely to be alive.

In a more recent study, researchers measured blood pressure and volunteering once at baseline and again four years later. They found evidence that older adults who volunteered at least four hours per week in the 12 months prior to the baseline blood pressure measurement were less likely to develop high blood pressure four years later.

Additional studies suggest that volunteering is associated with greater physical health in part because volunteering helps to buffer against stress and prevents against declines in functional health, such as declines in walking speed and physical strength.

So does being helpful cause better health?

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Latex Condoms Have Their Downfalls, So Researchers Invented This

Although latex condoms have been used with great success in the reproductive health arena, both in preventing pregnancy and preventing disease transmission, issues with using them are common. These range all the way from just not liking the latex to actually being allergic to it and therefore not able to use condoms made from it.

Now, new research with a hydrogel and an antioxidant aims to make condoms both better and something people will actually want to use.

In 2014, there were about 36.9 million people living with HIV and about 2 million were infected. The virus, which causes AIDS, is commonly spread through sexual activity, and although antiretroviral therapy has turned the once-universally fatal condition into a chronic one, 1.2 million people died as a result of AIDS-related diseases last year.

The United Nations group asked to combat HIV and AIDS advocates a “rapid scale-up of essential HIV prevention and treatment approaches.” It’s well accepted that condoms are one way to help prevent transmission, but they’re not a perfect solution.

Mahua Choudhury’s proposed male condom, which was featured in Men’s Journal’s9 Condoms of the Future,” has some innovative properties.

First, unlike most male condoms, it is not made of latex, but instead from a new material—a strong, elastic polymer called hydrogel, which is a gel made primarily of water that has a number of applications already, including contact lenses and other medical uses.

“Some people are allergic to latex, and others are just not comfortable with it,” says Choudhury, assistant professor at the Texas A&M Health Science Center Irma Lerma Rangel College of Pharmacy. “Therefore, we wanted to create a novel material.”

WHY AN ANTIOXIDANT?

To enhance its disease-preventing abilities, the condom will be enmeshed with a plant-based antioxidant that has been shown to have anti-HIV properties. This would be especially important if the condom were to break, for example, and thus neutralize its barrier effect. “If there is an accident or something happens,” Choudhury says, “this antioxidant will be released and prevent the replication of HIV.”

This antioxidant also has stimulant properties that can enhance the sexual experience and feelings of pleasure by promoting several physiological stimulations, all of which can help maintain erection and increase sexual pleasure. “If we succeed, it will revolutionize the HIV prevention initiative,” Choudhury says.

“We are not only making a novel material for condoms to prevent the HIV infection, but we are also aiming to eradicate this infection if possible.”

Finally, like all condoms, this one would also help prevent other sexually transmitted diseases and unplanned pregnancy.

LOW-COST, LATEX-FREE

For her proposal for this new type of condom, Choudhury is one of 54 applicants out of 1,700 to receive the Grand Challenge in Global Health award from the Bill & Melinda Gates Foundation, which funds individuals worldwide to solve persistent global health challenges. Their interest this round: an extremely low-cost, latex-free condom.

The condom material is essentially ready. Choudhury and her team have created the hydrogel and embedded the antioxidant, and it is going through the patent process now.

“We are trying to find how fast the enmeshed antioxidant can release,” she says, “and we don’t know if it will automatically release, or if you have to apply pressure.” This is something she and her team will look at in the testing process, which will happen in the next six months or so.

Choudhury hopes the condom can be made available to everyone, especially those who otherwise might not have access, such as people in rural areas of developing countries. “If you can make it really affordable, and really appealing,” she says, “it could be a life-saving thing.”

Republished from Futurity.org as a derivative work under the Creative Commons Attribution 4.0 International license. Original article posted on Futurity by 

Featured Image Credit: Guillaume Paumier/flickr

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