Author: Roheeni Saxena

(credit: Credit: JJ Harrison, via Wikimedia)

Malaria is a leading cause of disease and death in tropical and subtropical regions. Use of insecticidal nets, which are draped over beds while people sleep, has significantly reduced the incidences of malaria, along with the population of mosquitoes that transmit this disease. Unfortunately, long-term use of insecticides has led to the evolution of a mosquito population that is immune to insecticides.

A recent paper published in PNAS indicates that this might not be as grim as it seems. Mosquitoes that are resistant to the insecticide still suffer ill effects, including shortened lifespans and reduced ability to transmit malaria. So insecticide-laden sleeping nets should have a strong effect on transmission of malaria, even among insecticide resistant mosquito populations.

While most mosquitoes die within hours of exposure to the insecticides on bed nets, these experiments were designed to examine the populations of mosquitoes that survive for 24 hours or longer after exposure. As the mosquito populations are thinned by use of insecticides, more and more of the surviving generations of mosquitoes will fall within this group with prolonged post-exposure survival, so understanding these insects is important to future malaria prevention efforts.

Cigarette smoking causes emphysema, a disease characterized by serious structural damage to lung tissues. Smoke introduces oxidizing agents into the lung that activate inflammation and induce over-production of nitric oxide in lung tissues, leading to emphysema. A new paper published in PNAS shows that tobacco smoke exposure can be partly counteracted by doses of vitamin C and another drug, a selective nitric oxide synthase inhibitor. In other words, vitamin C could provide some protection against smoking-related lung damage.

The authors of this study have previously shown that cigarette smoke damages lung proteins via oxidation, but they hadn’t fully characterized the mechanisms involved. To further explore tobacco-induced lung damage, the researchers worked with a guinea pig model, exposing some animals to cigarette smoke and comparing them to controls. They found that exposed guinea pigs showed extensive breakdown of major lung structural proteins and that this damage helped foster emphysema.

The experiments also showed that smoke-exposed lungs had altered expression of nitric oxide synthase proteins, which resulted in increased production of nitric oxide in these tissues. Cigarette smoke exposure was directly linked to the presence of nitric oxide in exposed tissues and those tissues’ oxidative damage.

Vaccination has improved health and lengthened life spans over the last two centuries, but it takes time to develop vaccines in response to emergent health threats. A paper published in PNAS presents a new type of nanoparticle vaccine technology using RNA to encode proteins that trigger immune responses. This new vaccine technology could allow us to respond more quickly to new threats, potentially saving many lives during future outbreaks.

Currently, four types of vaccines are commonly used. Inactivated vaccines contain bacterial cells or viruses that are killed or inactivated—they can’t replicate, but they can produce an immune response. Attenuated vaccines contain live bacteria or viruses that have low virulence, so they will evoke an immune response, but won’t cause a full-fledged infection. Virus-like particle vaccines contain the shell of a virus, but lack any genetic material. Finally, subunit vaccines contain proteins derived from the infectious agent, which can provoke an immune response without introducing the pathogen.

The new vaccine technology presented in this paper relies on what’s called “replicon mRNA,” which is based on a deactivated virus. It can make copies of itself and trigger the production of the proteins it encodes but can’t make new viruses, so it never escapes beyond the cells it first gets into. Replicon mRNA can be used to produce large quantities of specific proteins within the body, which in turn can provoke an immune response against those proteins.

When the Montreal Protocol phased out the use of chlorofluorocarbons starting in 1989, scientists expected to see improvements in the Antarctic ozone hole that was opening each spring. They weren't anticipating anything immediate—instead, improvement was expected within 20 to 30 years of the protocol’s implementation. Ozone recovery occurs through distinct stages, including a reduction in the rate of ozone decline and a leveling off of the depletion. Only once these are done should we expect to see an ozone increase, termed “ozone healing.”

Previous studies of the Antarctic ozone have provided evidence that the early phases of ozone recovery have been occurring. A new paper published in Science presents the first signs ozone healing may be occurring as well. The data shows an overall increase in the thickness and abundance of the Antarctic ozone layer in the last 15 years.

The Antarctic ozone hole fluctuates in size over the course of a year. It is largest during the spring, which occurs from September to November in the southern hemisphere. Historically, the majority of each year’s ozone hole growth occurs in late August and early September, building to a peak in October.

A migraine is one of the most common health issues worldwide, affecting up to one in five people. But the mechanisms that drive migraines aren’t well understood. In fact, doctors and scientists are still trying to figure out if migraine is primarily a vascular or a neurological disorder.  A new genome-wide association study published in Nature Genetics suggests that a migraine may be primarily stem from problems with the blood supply.

The data in this paper comes from a meta-analysis of 22 genome-wide association studies, a combined dataset of over 35,000 migraine cases and even more controls. The primary meta-analysis found associations between migraines and 38 independent genomic regions, 34 of which were associated with migraines for the first time by this study.

When the authors characterized the genes near these associated loci, they found that a number of them were previously associated with vascular disease. Others are involved in smooth muscle contraction (smooth muscle lines larger blood vessels) and regulation of vascular tone. Some of these genes were also associated with arterial functioning.

Autonomous vehicles will likely become available in the near future, a reality that raises ethical questions about their programming. A new article published in Science raises a classical ethical question within the context of that new reality: should a car sacrifice its driver if doing so will save the lives of many pedestrians? The article found that participants generally do want cars to be programmed in this way for other drivers, but they don’t want their own cars to work this way. It’s a potentially lethal form of “Not-In-My-Backyard” for our more automated future.

For this paper, researchers conducted six online surveys between June and November of 2015. Participants were recruited through the Amazon Mechanical Turk platform. Each of the six online surveys included approximately 200 to 450 participants.

Public good vs. individual behavior

In the first survey, 76 percent of participants said that it was morally correct for self-driving cars to sacrifice one passenger to save 10 pedestrians. That’s an overwhelming preference for cars to be programmed in a utilitarian way, reducing the overall number of casualties in an accident. These participants did not express any concerns about programming being too utilitarian.

Reproducibility of findings has been a hot-button issue in social science over the last year, and as the election approaches, the reproducibility of findings related to voting is especially relevant. A recent study published in PNAS reassesses previously published data about ways to increase voter turnout and finds that language cues actually don’t have a significant effect on voter behavior.

The study revisits some field experiments conducted by Bryan et. al., which were also published in PNAS. These earlier experiments looked at voter behavior during the 2008 presidential election in California and the 2009 gubernatorial election in New Jersey. Using online surveys to prime voters, the previous study had shown that use of nouns or verbs affected whether voters went to the polls—verbs did better at getting out the vote.

This new study follows up on that work, looking at how subtle language manipulations can prime the behavior of voters.

If one eye is temporarily or permanently damaged, the visual cortex will rewire itself, devoting more resources to the remaining functional eye. This change is reversible if binocular vision is restored. But until a recent study published in Science, we didn’t know how the brain manages to reallocate its resources. This new study shows that this change happens at the level of individual cells, which can shift their attention to eyes as needed.

The visual cortex functions by integrating information from the neurons that are wired to one of an animal’s two eyes. If you cover one eye up for long enough, there’s a shift where the other eye becomes dominant, and more of the visual cortex is devoted to the working eye. This occurs in many animals, including carnivores, primates, and rodents—in mice, this shift in dominance is reversible. What we haven't known is how it takes place. Does the visual cortex contain entire tissues devoted to different eyes that it repurposes, or do individual cells change their connections to follow different eyes?

The scientists used a technique called ratiometric calcium imaging, which allowed them to see excitatory changes in calcium concentration within the neurons, an indication that they're busy processing signals. The team used this to follow the sight-driven activity in the binocular visual cortex of adult mice.

Lower-income and minority college students often have trouble sticking with higher education. But past studies have indicated they’d be less likely to drop out of school if they receive appropriate counseling once they start experiencing academic problems. A new study published in PNAS demonstrates that if students receive this kind of intervention prior to college enrollment and during their first year at college, they are more likely to avoid having academic trouble in the first place. And the counseling can be done over the Internet.

The counseling involves letting students know that it is common for students to struggle with the transition to college, and that this transition will get easier with time. This is known as a “lay theory intervention.”

The researchers conducted three double-blind randomized experiments to test the effects of internet-based interventions for students who come from socially and economically disadvantaged backgrounds. Students in experimental groups received one of the following: an intervention focused on developing their confidence; an intervention focused on developing their feelings of social belonging in college; or an intervention that included both of these.

Implicit biases are unconscious attitudes or stereotypes that affect how we perceive others; they sometimes run contrary to our conscious beliefs. Employers and law enforcement officers have faced criticism about implicit bias in the hiring of new employees and arresting of potential criminals. The American Association for the Advancement of Science (AAAS), the organization that publishes Science magazine, recently looked into the role of implicit biases in the scientific review processes.

The issue of implicit bias in the peer review process is significant because a strong publication record is critical to success in most science and engineering fields. Bias in the grant review process may determine which scientists are able to continue working in their field. If some groups of people are less likely to publish and get funding, then the professional sphere of science will remain more homogeneous.

This is problematic because diverse groups tend to be more creative and innovative. If the peer review process is preventing science from becoming as diverse, then innovation is likely being held back as well.