Malaria from many angles

World Malaria Day may have come and gone, but our PLoS ONE authors certainly seem to be keeping in the spirit, with three new malaria-related publications in the last week.

On Friday, we published “Distributed Medical Image Analysis and Diagnosis through Crowd-Sourced Games: A Malaria Case Study,” by a group of authors from University of California, Los Angeles. Today we have two more to add to the list: “Investigation of Host Candidate Malaria-Associated Risk/Protective SNPs in a Brazilian Amazonian Population,” from an international team of authors from Brazil and the UK, and “Algae-Produced Pfs25 Elicits Antibodies that Inhibit Malaria Transmission,” from University of California, San Diego.

I love how these articles all tackle aspects of a single problem, but in such different ways, from the patient to the mosquito host to the causative parasite, and from diagnosis to treatment to prevention. This breadth of coverage highlights the incredible richness and diversity of malaria research, and of the broader scientific research community as well, which is very important for a multidisciplinary – and frequently interdisciplinary – journal like PLoS ONE.


Mavandadi S, Dimitrov S, Feng S, Yu F, Sikora U, et al. (2012) Distributed Medical Image Analysis and Diagnosis through Crowd-Sourced Games: A Malaria Case Study. PLoS ONE 7(5): e37245. doi:10.1371/journal.pone.0037245

da Silva Santos S, Clark TG, Campino S, Suarez-Mutis MC, Rockett KA, et al. (2012) Investigation of Host Candidate Malaria-Associated Risk/Protective SNPs in a Brazilian Amazonian Population. PLoS ONE 7(5): e36692. doi:10.1371/journal.pone.0036692

Gregory JA, Li F, Tomosada LM, Cox CJ, Topol AB, et al. (2012) Algae-Produced Pfs25 Elicits Antibodies That Inhibit Malaria Transmission. PLoS ONE 7(5): e37179. doi:10.1371/journal.pone.0037179

So I’m a doctor – now what? Post-PhD career choices

The road to a PhD is long and hard, and it’s natural that students’ goals for the future would change over the course of their education. Anecdotal evidence abounds – just ask anyone who’s been through it – and now a study published last week in PLoS ONE shows that students close to graduation are less interested in pursuing faculty careers than are their younger counterparts.

The authors, Henry Sauermann from Georgia Institute of Technology and Michael Roach from University of North Carolina, investigated the attractiveness of different careers to over 4,000 PhD students at different stages in their training in the life sciences, chemistry, and physics at 39 different US tier-one research universities. Across the board, late stage students, defined as those who were looking for jobs or were planning to do so within a year, found faculty jobs less attractive than did early stage students, who had not yet completed their qualifying exam or similar milestones.

There were some interesting distinctions between the responses from chemistry students and the biologists and physicists that caught my attention. My PhD is in chemistry, but I conducted my research in a biology lab, and I felt like the cultures were very different – a distinction that appears to be borne out in the numbers.

From the beginning, the chemistry students in the study were much less interested in faculty positions than were either the biologists or the physicists: only 23% of early stage chemistry students declared a research-focused faculty position to be extremely attractive, as compared to 39% for biologists and 37% for physicists. Furthermore, chemists’ interest in working for either an established firm or a start-up showed huge increases from early to late stage, even though their initial interest in these types of positions was already high relative to their counterparts in biology or physics.

The authors don’t discuss potential reasons for these differences, but my impression is that industry jobs in chemistry are simply more common and more accessible than those in biology. This may not always be the case, but it will be interesting to see how both the academic and industrial cultures evolve as research – and the accompanying funding – goes in new directions.

Citation: Sauermann H, Roach M (2012) Science PhD Career Preferences: Levels, Changes, and Advisor Encouragement. PLoS ONE 7(5): e36307. doi:10.1371/journal.pone.0036307

Identical twins caught red-fingered

Fingerprints are as unique as snowflakes – or so we’re taught in elementary school. Identical twins, though, provide an interesting caveat to this rule: Not only do they look alike, they are also more likely than non-twins to have similar fingerprint patterns.

These similarities raise potential complications for biometrics-based security systems and crime solvers, but a PLoS ONE paper published Friday suggests there’s no reason to worry.

The study, conducted by an international team of researchers from the Chinese Academy of Sciences and the University of Iowa, looked at fingerprints from 83 pairs of identical twins. They collected each print six times, rather than the single impression that is usually collected, and used two different identification methods, called P071 and VeriFinger 6.1, and novel analytical methods to evaluate the prints. They found that identical twins’ fingerprints had a 74% probability of being the same type (though not identical), as compared to a 32% probability for a random pair of prints, but they also showed that the fingerprints could be distinguished using the sophisticated identification methods.

Based on these results, it looks like identical twins may not be the perfect criminals after all. Nevertheless, they seem to have a leg up on the rest of us – maybe something to keep in mind the next time you’re trying to solve that thorny art heist.

Citation/Image source: Tao X, Chen X, Yang X, Tian J (2012) Fingerprint Recognition with Identical Twin Fingerprints. PLoS ONE 7(4): e35704. doi:10.1371/journal.pone.0035704

Observing World Malaria Day 2012: Sustain Gains, Save Lives

Today is the fifth annual World Malaria Day, commemorated every April 25 to recognize and encourage global efforts to control malaria. This year’s theme, “Sustain Gains, Save Lives: Invest in Malaria,” alludes to the many important advances against the malaria parasite that have been achieved in recent years, but also includes a warning: we must continue to invest in malaria research and maintain our vigilance to ensure that painstakingly earned gains are not surrendered to complacency.

Based on the 251 malaria-related PLoS ONE papers published since last year’s World Malaria Day, it’s pretty clear to us that the research community is maintaining its commitment to this disease. Instead of trying to provide an overview of all of these articles, which cover perspectives as diverse as public health, ecology, and microbiology, we decided to observe the day by highlighting a single article that, like this year’s theme, emphasizes the importance of continued research as the parasite proves itself to be a constantly evolving target.

The study, published last October, monitors drug resistance in the causative parasite Plasmodium falciparum in Mozambique over five years, from 2006 to 2010, as the recommended drug treatment was adjusted. The researchers, led by Jaishree Raman of the South African Medical Research Council, found that the incidence of parasitic resistance to the originally recommended drug regimen increased significantly over the course of the study, from 56.2% at the start up to 75.8% in 2010. This approximately 20% leap in resistance suggested that the preferred treatment at the time would become much less effective as its use increased.

However, the Mozambican Ministry of Healthy preempted this scenario by changing their recommended front-line drug treatment in 2008. The authors weren’t able to study the full impact of this policy change, though, because it was not fully deployed until 2010, at which point the study was winding down – further highlighting the need for continued careful monitoring as new treatments are introduced.

You can learn more about World Malaria Day at Roll Back Malaria and the World Health Organization, and read about some additional malaria papers from last year’s World Malaria day post.

Citation: Raman J, Mauff K, Muianga P, Mussa A, Maharaj R, et al. (2011) Five Years of Antimalarial Resistance Marker Surveillance in Gaza Province, Mozambique, Following Artemisinin-Based Combination Therapy Roll Out. PLoS ONE 6(10): e25992. doi:10.1371/journal.pone.0025992

Image source: eyeweed on Flickr

High altitude genetic juggling

Tibetans and Incas are so well adapted to their high altitude homes that the low oxygen levels don’t even faze them, but for those of us living near sea level, traveling up to the mountains can put a lot of stress on our bodies.  Even so, we can still do some of our own short-term biological adjustments, and a new study published today in PLoS ONE identifies some of the specific genetic changes that are involved in this high altitude acclimation.

The research team, composed of 26 scientists from institutions in China and Denmark, studied four climbers of Himalayan peak Mount Xixiabangama, which rises 8,012 meters, or 26,286 feet, above sea level. (For comparison, Mount Everest is 8,848 meters tall.)  They collected blood samples before, during, and after the trip, which took almost 30 days, and then determined how the climbers’ gene expression – which genes were “on” or “off” – changed over time.

Changing gene expression is one of the fastest ways to adjust to a new environment or situation. The DNA itself can’t change to accommodate rapidly developing needs, but gene expression is can change quickly and plays a large role in determining how a cell behaves. By looking at the climbers’ gene expression, the researchers aimed to find out which genes were most important for the physiological changes that helped the climbers temporarily adjust to life at high altitude.

The results showed a complex network of expression changes, particularly for genes involved in red blood cells and inflammation, which makes sense given the unique rigors of high altitude climbing. As a climber myself (though not nearly to the same extent as those in this study), I’m now left with the question of how my own gene expression may change while I’m on the wall.

Citation: Chen F, Zhang W, Liang Y, Huang J, Li K, et al. (2012) Transcriptome and Network Changes in Climbers at Extreme Altitudes. PLoS ONE 7(2): e31645. doi:10.1371/journal.pone.0031645

Image source: Rupert Taylor-Price on Flickr

What elephants want: Ranging and raiding in Asia and Africa

Forget the elephant in the room. Try the elephant on the farm, raiding crops for a tasty treat while risking the wrath of frustrated farmers.

This tug-of-war for territory and resources is just one manifestation of the growing tensions between economic development and environmental conservation, and today we have two papers, from two continents, that provide new information about how we might be able to strike the right balance between sometimes conflicting development goals.

The first study compares the behavior of Asian elephants in fragmented versus non-fragmented forests in Borneo. Using a satellite tracking program to monitor five female elephants, the researchers found that the home range, or the area covered by a wild animal over the course of a year, for elephants in non-fragmented forest was approximately 250 to 400 square kilometers. When the forest was fragmented, though – primarily by human developments such as roads, farms, and villages – the home range nearly doubled, to about 600 square kilometers.

The authors, led by Raymond Alfred of Sabah University of Malaysia, suggest that the significant increase in the home range could reflect increased difficulty in satisfying food and water needs in a highly fragmented environment. Their results could possibly help alleviate some of this elephant stress by providing guidelines for determining how much space is needed for long-term elephant preserves.

Using such guidelines could also help control elephant crop raiding, which has become a major problem in both Asia and Africa. As people move into  elephant habitat, elephants have begun sampling their crops to enrich their diet – leading farmers to sometimes kill the thieves, which is particularly concerning given the conservation listings for both Asian (endangered) and African (vulnerable) elephants.

There has been some work to develop methods to protect both the elephants and the crops, including installing “beehive fences” as deterrents (see this paper for more information about the surprising relationship between elephants and bees), but today’s paper, led by Patrick Chiyo of University of Notre Dame, takes a different angle, looking at what can cause an elephant to initiate crop-raiding behavior.

Crop raiding is known to be more common among male than female elephants, so the team investigated the raiding behavior of male African elephants in Amboseli National Park in Kenya. Out of about 365 male elephants, they identified 43 individual crop raiders, and estimated that there could be an additional 40 perpetrators who remained undetected. In other words, about 20% of the male elephants may be raiders. Males at their reproductive peak were nearly twice as likely to raid, and the authors suggest that his behavior could be due to increased energetic needs for mating, or increased risk-taking behavior associated with their age.

Furthermore, the elephants were more likely to raid if their elephant “friends” were raiders as well. It’s not all about peer pressure though – the effect gets stronger the older the raider friends are, suggesting that the elephants are actually learning from their older, wiser companions. This implied intelligence should come as no surprise, given all the evidence for elephant smarts (see, for example, this study on elephant learning) – and it makes me think that, conservation concerns aside, elephants might have something to teach us about respecting our elders.

Image source: brittanyhock on Flickr

Bug love: The fascinating story of the fig wasp

About 10 years ago, I had quite a scare when my high school biology teacher warned us away from figs because their insides were crawling with wasps. Some internet research revealed that this claim was only partly true, so I continued along my fig-consuming way without thinking much more of it.

That is, until today, when we published a paper titled “Moving your sons to safety: galls containing male fig wasps expand into the centre of figs, away from enemies,” which made me look deeper into this symbiotic relationship – and now I’m eager to share all the creepy crawly details I found.

The short story is that fig wasps lay their eggs inside the fruit, where they hatch and mate. The female then crawls out of the fig, through a tunnel chewed by the male, and eats her way into a new fig to lay her eggs. In the process, she loses her wings and antennae and dies, trapped, inside the new fig, which she has also pollinated.

As for the caveats: there are also species of self-pollinating figs, which do not require the wasps, and species of parasitic fig wasps that game the system, taking advantage of the figs as incubators without doing their pollination duty. (I’m still not sure which ones make it to the supermarket though.)

Today’s paper explores some of the differences in egg-laying behavior between pollinating, symbiotic wasps and non-pollinating, parasitic wasps. Non-pollinating wasps not only take advantage of the fig, but sometimes also kill the larvae of pollinating wasps. In response to this threat, it appears that pollinator wasps have developed some defense mechanisms, including the location and sex ratio of eggs laid, the authors report.

Wasps aside, I also learned a surprising piece of information about figs themselves. They are not fruits, but are actually something called an “inflorescence,” or a cluster of flowers. It’s just that the flowers are hidden on the inside: each crunchy little seed in a fig represents one flower. To make it more complicated, there are three different types of flowers: male, short female, and long female. Female fig wasps can only reach and lay their eggs in the short female flowers, so the long female flowers are left to develop fig seeds, allowing both the fig and the wasp to prosper.

Image source: Mundoo via Flickr

Mating versus immunity: an insect’s dilemma

Relationships are all about compromise, as any good advice columnist will tell you.

It’s a little different for insects though. Instead of deciding who makes dinner and who does the dishes, they have to make a choice between mating success and survival – and two papers published today explore some of the subtleties of this literal life-and-death trade-off.

Both reproducing and maintaining a healthy immune system are biologically expensive, so insects have to make smart choices about where to allocate their energetic resources, especially when they’re going through lean times. Previous work has often considered the biological cost of reproduction from the female’s perspective, but both of today’s papers investigate the other side of the coin: how males deal with this evolutionary conundrum.

Producing sperm can be hard work, so males need to be smart about it, and allocate their resources appropriately. In “Ejaculate economics: testing the effects of male sexual history on the trade-off between sperm and immune function in Australian crickets,” the authors report that male Australian crickets produce higher quality sperm when they are housed with sexually mature females than with immature females. The crickets couldn’t maintain this high quality sperm indefinitely though; at 13 days, the sperm quality was approximately the same for all the crickets, regardless of their cage-mates.

The researchers, led by Damian Dowling of Monash University in Australia, also found that better sperm was correlated with decreased immune response. The correlation was weak, but the authors argue that it is likely to be biologically relevant, and fits with the hypothesis that males must choose between allocating resources to reproduction or immunity. In this case, it appears that the better sperm, and the resulting increase in possible reproductive success, was worth the risk of decreased immune readiness.

The other study, “Sex, War, and Disease: The role of parasite infection on weapon development and mating success in a horned beetle (Gnatocerus cornutus),” led by Jeffery Demuth of University of Texas at Arlington, focuses on one specific reproductive element: male weapons. On the horned beetle, that’s – you guessed it – the horn.

To test the relationship between immunity and horn size, the researchers infected broad-horned flour beetles with a tapeworm. They found that parasite infection significantly decreased horn length, but had a much smaller effect on overall body size.

These results, together with the hypothesis that the immune-challenged beetles should allocate their resources to the most important factors for reproductive success, suggest that body size, rather than horn size, should be more strongly correlated with mating success – and the results from arranged mating battles bear this out.

In other words, it appears that the beetles made the right choice when they were challenged with the parasite. They retained their best possible mating chances by maintaining their body size as much as they could and instead compromising on horn length, presumably reallocating those resources toward fighting the parasite.

Of course, none of these “choices” are conscious, but the innate biological responses are still pretty remarkable.

Image credit: Isfugl via Flickr

Tweet for the sake of science

Social networking is a big deal, and not just for smart phone-addicted teens and reconnecting with long-lost friends. Twitter has grown into an incredibly useful way to disseminate information, and many reputable institutions, including PLoS and PLoS ONE, use it to share news and updates with thousands of people across the world.

Researchers are beginning to key into the movement too, not just as users, but also as active investigators of the dynamics and utility of these new technologies as they emerge and grow. One of the amazing effects of these social networking sites is the wealth of data they can provide, and now scientists are taking advantage of the huge amount of public content from sites like Twitter, Facebook, and even Wikipedia to answer all kinds of new questions.

For example, investigators showed that Twitter is a useful tool for tracking H1N1 here and here; that content disputes in Wikipedia reflect geopolitical instability; and that virtual social networks can create collective emotional states.

Today, we added to this growing body of work with a report of a Twitter-based “hedonometer” that can be used to quantify the societal happiness of large populations. The authors used an amazing library of 46 billion words from nearly 4.6 billion tweets posted over almost three years by over 63 million unique users – a collection that would have been essentially impossible to obtain without the Twitter-verse.

The paper reports various trends in happiness – people are happier on the weekend, and the word “Christmas” is associated with high happiness levels, as opposed to “flu” and “Iraq,” which rank at the bottom – but the real advancement of the paper is its quantitative approach to the huge Twitter-based dataset. While scientists now have access to these huge datasets, they must first face the challenge of classifying and organizing the huge amounts of social information so they can conduct meaningful research into areas that have not previously been explored.

Image courtesy of La Fabrique de Blogs

A very PLoS ONE Thanksgiving

In honor of Thanksgiving, I thought I’d share a veritable cornucopia of PLoS ONE holiday-related papers old and new.

Tryptophan is the chemical traditionally credited for common post-gorging sleepiness, but does a lot more than that too. As one of the twenty amino acid building blocks for proteins, it serves all sorts of crucial biological functions, and it’s also involved in treatments for depression, HIV-related immune responses, and behavior regulation in 10-year-olds.

Then there are the cranberries, boiled into sauce or grated into relish, which are known to have health benefits due to their antioxidant and nutrient content, including a family of compounds called flavonoids. This paper published in October reported that obese mice treated with cranberry-derived flavonoids showed improvements in their weight-related symptoms, and identified the particular molecular pathway responsible for this effect – though I’m not going to go so far as to suggest that heaping an extra serving of cranberry sauce on your turkey will keep you from needing to undo your belt buckle this holiday.

And if you’re having pumpkin pie for dessert, you might want to consider garnishing it with some of the leaves. According to this paper, pumpkin leaves are a good source of plant-based protein, although the best balance of amino acids would come from combining it with seaweed and spirulina (a common dietary supplement that is made primarily from cyanobacteria).

On second thought, maybe you should just leave the pie as is.

Instead, if apple pie is more up your alley, it may also be good to know that apple orchards can be protected from caterpillar damage by offering nest boxes for bird species like the great tit. A recent study also showed similar results for nest boxes in vineyards – in case you’re planning to have a glass of wine with your meal.

Regardless of what you’re eating or drinking for the holiday, happy Thanksgiving from PLoS ONE!

One fish, two fish, old fish, new fish

A search of PLoS ONE publications for the term “fisheries” shows over 700 published on the topic, many measuring or modeling their ecological effects, and today we add another to the collection. But this new addition, published earlier this week, has an interesting twist – it uses archaeological evidence to show fishery establishment in the Baltic by the 15th century.

The researchers analyzed bones of the eastern Baltic cod from medieval sites around the Baltic. The large international team, which included researchers from institutions in the UK, Sweden, Germany, Denmark, Belgium, Norway, Denmark, Canada, Poland, and Estonia, used the elemental content of the bones to determine where the fish had originally come from. They found that fish from the 13th and 14th centuries had largely been imported to the area, likely from Norway. Then, in the 15th century, and perhaps as early as the late 14th century, the fish appear to have a local origin, indicating that a Baltic fishery had been established, at least 100 years before it was documented in the written record.

There is evidence of other fisheries that were established earlier – for example, the cod imported from Norway came from fisheries developed by the 11th or 12th centuries – but this new report provides an interesting historical and ecological perspective on an issue that is obviously still a major subject of research. Fisheries may go back hundreds of years, but it’s clear that we need to carefully weigh our options to determine what their future should look like.

An ocean of pheromones

Human pheromones have been the source of quite a bit of speculation, and while they may have some effect on sexual attraction, it certainly doesn’t appear that they are required for mating. The story for diatoms, though, is exactly the opposite, according to a study published today.

These tiny unicellular creatures live in the ocean, where it is easy to imagine that an egg and sperm might have trouble finding each other. To solve this problem, they have evolved a system where pheromones actually orchestrate the whole process, so that egg and sperm are only released on cue, hopefully making it easier for them to connect.

Here’s how it works. The females release their sex pheromone, called ph-1, constantly. Then, when a male is nearby, he senses the pheromone, which triggers him to make and release sperm. At the same time, he also begins to produce his own sex pheromone, called ph-2, which makes the female produce and release her eggs. The researchers suspect that there is yet a third pheromone, called ph-3, that is then released by the eggs to continue attracting the sperm. However, while they detected ph-1 and ph-2 in their experiments, ph-3 was not directly observed.

By relying on these chemical signals, the diatoms make sure that they are only releasing their gametes when a potential partner is nearby, which keeps them from wasting lots of energy. This elegant solution so far appears unique among related organisms.

The researchers also found some other cool elements of the diatom’s reproductive cycle, like “threads” on the sperm that help it move and grab things, and “blobs” on the sperm with unknown function. Check out these movies for a look!

This post was written by Rachel Bernstein, an associate editor at PLoS ONE.