3000 Years Ago, We Were What We Ate

Posted on March 14, 2014 by Kayla Graham

For many of us, moving to a new house means recruiting a couple good friends to help pack and haul boxes. After a day or two of work, everyone shares a pizza while resting tired muscles at the new home. But 3000 years ago, enjoying a post-move meal may have required a little more planning. Early settlers of remote tropical islands in the Pacific had to bring along all resources needed for survival, including food, from their original homes overseas.

The Lapita people were early settlers of islands in the Pacific, called Remote Oceania (pictured below). When these people, whose culture and biology links to Southeast Asian islands, first decided to sail to the island Vanuatu, they brought domestic plants and animals—or what you might call a ‘transported landscape’—that allowed them to settle this previously uninhabited, less biodiverse (and less resource-available) area. However, the extent to which these settlers and their domestic animals relied on the transported landscape at Vanuatu during the initial settlement period, as opposed to relying on the native flora and fauna, remains uncertain.

To better understand the diet and lives of the Lapita people on Vanuatu, archaeologist authors of a study in PLOS ONE analyzed the stable carbon, nitrogen, and sulfur isotopes from the bones of ~ 50 adults excavated from the Lapita cemetery on Efate Island, Vanuatu.

Why look at isotopes in human remains? Depending on what we eat, we consume varying amounts of different elements, and these are ultimately deposited in our bones in ratios that can provide a sort of “dietary signature”; in this way, the authors can investigate the types of plants, animals, and fish that these early people ate.

For instance, plants incorporate nitrogen into their tissue as part of their life cycle, and as animals eat plants and other animals, nitrogen isotopes accumulate. The presence of these different ratios of elements may indicate whether a human or animal ate plants, animals, or both. Carbon ratios for instance differ between land and water organisms, and sulfur ratios also vary depending on whether they derive from water or land, where water organisms generally have higher sulfur values in comparison to land organisms.

Scientists used the information gained about the isotopes and compared it to a comprehensive analysis of stable isotopes from the settlers’ potential food sources, including modern and ancient plants and animals. They found that early Lapita inhabitants of Vanuatu may have foraged for food rather than relying on horticulture during the early stages of colonization. They likely grew and consumed food from the ‘transported landscape’ in the new soil, but appear to have relied more heavily on a mixture of reef fish, marine turtles, fruit bats, and domestic land animals.

The authors indicate that the dietary analysis may also provide insight into the culture of these settlers. For one, males displayed significantly higher nitrogen levels compared to females, which indicates greater access to meat. This difference in food distribution may support the premise that Lapita societies were ranked in some way, or may suggest dietary differences associated with labor specialization. Additionally, the scientists analyzed the isotopes in ancient pig and chicken bones and found that carbon levels in the settlers’ domestic animals imply a diet of primarily plants; however, their nitrogen levels indicate that they may have roamed outside of kept pastures, eating foods such as insects or human fecal matter. This may have allowed the Lapita to allocate limited food resources to humans, rather than domestic animals.

Thousands of years later, the adage, “you are what you eat” or rather, “you were what you ate” still applies. As the Lapita people have shown us, whether we forage for food, grow all our vegetables, or order takeout more than we would like to admit, our bones may reveal clues about our individual lives and collective societies long after we are gone.

Citation: Kinaston R, Buckley H, Valentin F, Bedford S, Spriggs M, et al. (2014) Lapita Diet in Remote Oceania: New Stable Isotope Evidence from the 3000-Year-Old Teouma Site, Efate Island, Vanuatu. PLoS ONE 9(3): e90376. doi:10.1371/journal.pone.0090376

Image 1: Efate, Vanuatu by Phillip Capper

Image 2: Figure 1

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The Science of Snakeskin: Black Velvety Viper Scales May be Self-Cleaning

Posted on March 8, 2014 by Michelle Dohm

West African Gaboon viper

Whether you love them or hate them, snakes have long captivated our interest and imagination. They’ve spurred countless stories and fears, some of which may have even affected the course of human evolutionary history. We must admit, there is something a little other-worldly about their legless bodies, willingness to swallow and digest animals much bigger than them, and fangs and potentially fatal (or therapeutic?) venomous bites.

Not least of all, their scaly skin is quite mesmerizing and often laden with intricate and beautifully geometric patterns just perfect for camouflaging, regardless of whether they live high up in a tree, deep in murky waters, or on the forest floor. Snakeskin was the focus of recent research by the authors of this PLOS ONE study who sought to determine whether it has any special properties less obvious to the naked eye.

Please meet the West African Gaboon viper, Bitis gabonica rhinoceros (pictured above). Native to the rainforests and woodlands of West Africa, these large, white-brown-and-black snakes can be identified by large nasal horns and a single black triangle beneath each eye—nevermind that, because they also lay claim to titles for the longest fangs and most venom volume produced per bite. The pattern of their skin is intricate and excellent for camouflage, and the black sections have a particularly velvety appearance. These eye-catching characteristics intrigued zoology and biomechanics researchers from Germany, who decided to take a closer look.

In a previously published paper, the authors analyzed the Gaboon viper’s skin surface texture by using scanning electron microscopy (SEM), as well as its optical abilities by shining light on the snakeskin in different ways to see how it’s reflected, scattered, or transmitted. They found that only the black sections contained leaf-like microstructures streaked with what they call “nanoridges” on the snake scales, a pattern that has not been observed before on snakeskin. What’s more, the black skin reflects less than 11% of light shone on it—a lot less than other snakes—regardless of the angle of light applied. The authors concluded from the previous study that both of these factors may contribute to the viper’s velvet-like, ultra-black skin appearance.

Scanning electron microscopy (SEM) of viper scales

In their most recent PLOS ONE paper titled “Non-Contaminating Camouflage: Multifunctional Skin Microornamentation in the West African Gaboon Viper (Bitis rhinoceros),” the authors conducted wettability and contamination tests in hopes of further characterizing the viper skin’s properties, particularly when comparing the pale and black regions.

To test the wettability of the viper scales, the authors sprayed droplets of water, an iodide-containing compound (diiodomethane), and ethylene glycol on the different scale types shown above, on both a live and dead snake, and then measured the contact angle—the angle at which a liquid droplet meets a solid surface. This angle lets us know how water-friendly a surface is; in other words, the higher the contact angle, the less water-friendly the surface.

Contact angle (A) and snake skin with water droplet on light and dark areas (B)

As you can see in the graph above, the contact angle was different depending on the liquid applied and the type of scale; in particular, the contact angle on the black scales was significantly higher than the others, in a category that the authors refer to as “outstanding superhydrophobicity,” or really, really, really water-repelling. This type of water-repelling has been seen in geckos, but not snakes.

Water droplet appearance on live snake skin

The authors then took some of the snake carcass and dusted it with a sticky powder in a contamination chamber, after which they generated a fog for 30 minutes and took pictures.

Skin before dusting (A), skin under black light after dusting (B), skin under black light after fogging (C), section of SEM, showing light and dark skin (D)

After 30 minutes of fogging, the black areas were mostly free of the dusting powder, while the pale areas were still completely covered with dust. The powder itself was also water-repelling, and so the authors showed that despite this, the powder rolled off with the water rather than sticking to the black areas of snake skin. Therefore, as suggested by the authors, this could be a rather remarkable self-cleaning ability. The authors suspect that the “nanoridges,” or ridges arranged in parallel in the black regions, may allow liquid runoff better than on the paler areas of the snake.

How does this texture variation help the snake, you ask? The authors posit that all these properties basically contribute to a better form of camouflage. If the snake were completely covered in one color, it may stand out against a background of mixed colors (or “disruptive coloration”), like that of a forest floor. If the black regions have fairly different properties from the paler regions, mud, water, or other substances would rub off in these areas and continue to provide the light-dark color contrast and variation in light reflectivity that helps the snake do what it does best: slither around and blend in unnoticed.

Citations

Spinner M, Kovalev A, Gorb SN, Westhoff G (2013) Snake velvet black: Hierarchical micro- and nanostructure enhances dark colouration in Bitis rhinoceros. Scientific Reports 3: 1846. doi:10.1038/srep01846

Spinner M, Gorb SN, Balmert A, Bleckmann H, Westhoff G (2014) Non-Contaminating Camouflage: Multifunctional Skin Microornamentation in the West African Gaboon Viper (Bitis rhinoceros). PLoS ONE 9(3): e91087. doi:10.1371/journal.pone.0091087

Images

First image, public domain with credit to TimVickers

Remaining images from the PLOS ONE paper

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Infectious Earworms: Dealing with Musical Maladies

Posted on March 5, 2014 by Souri Somphanith

This menace may leap out at you in the subway or find you when you’re tucked away, safe in your bed; it might follow you when you’re driving down the street or running at the gym. Hand sanitizer can’t protect you, and once you’re afflicted, the road to recovery can be a long one. However, this isn’t the Bubonic plague or the common cold—instead, the dreaded earworms!

Derived from the German word ohrwurm, which translates literally to “ear-worm,” an earworm commonly refers to a song, or a snippet of a song, that gets stuck in your head. Earworms can occur spontaneously and play in our heads in a seemingly infinite loop. Think of relentlessly catchy tunes, such as “Who Let the Dogs Out?,” “It’s a Small World,” or any Top 40 staple. An estimated 90% of people fall prey to an earworm at least once a week and most are not bothersome, but some can cause distress or anxiety. And yet, despite the earworm’s ubiquity, very little is known about how we react to this phenomenon. With the assistance of BBC 6 Music, the authors of a recent PLOS ONE study set out to connect the dots between how we feel about and deal with these musical maladies.

Researchers drew upon the results of two existing surveys, each focusing on different aspects of our feelings about earworms. In the first, participants were asked to reflect on whether they felt positively or negatively toward earworms, and whether these feelings affected how they responded to them. The second survey focused on how effective participants felt they were in dealing with songs stuck in their heads. Responses to both surveys were given free form.

To make sense of the variety of data each survey provided, the authors coded participant responses and identified key patterns, or themes. Two researchers developed their own codes and themes, compared notes and developed a list, as represented below.

Survey responses. Participants either chose to “cope” with their earworms or “let it be.”

The figure above represents responses from the first survey, in which participants assigned a negative or positive value to their earworm experiences and described how they engaged with the tune. The majority didn’t enjoy earworms and assigned a negative value to the experience. These responses were clustered by a common theme, which the researchers labelled “Cope,” and were associated with various attempts to get rid of the internal music. A significant number of participants reported using other music to combat their earworms.

Participants in the second survey, which focused on the efficacy of treating earworms, responded in a number of different ways. Those whose way of dealing was effective often fell into one of two themes: “Engage” or “Distract.” Those that engaged with their earworms did so by, for example, replaying the song; those that wanted distraction often utilized other songs. Most opted to engage.

Ultimately, the researchers concluded that our relationships with these musical maladies can be rather complex. Yet, whether you embrace these catchy tunes or try to tune them out, the way we feel about earworms is often connected to how we deal with them.

Want to put in your two cents? You can tell the authors how you deal with earworms at their website, Earwormery. For more on this musical phenomenon, listen to personal anecdotes on Radiolab, read about earworm anatomy at The New Yorker, or dig deeper in the study.

Citation: Williamson VJ, Liikkanen LA, Jakubowski K, Stewart L (2014) Sticky Tunes: How Do People React to Involuntary Musical Imagery? PLoS ONE 9(1): e86170. doi:10.1371/journal.pone.0086170

Images: Record playing by Kenny Louie

Figure 1 from the paper.

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It’s Not Easy Being Green: Assessing the Challenges of Urban Community Gardening

Posted on February 13, 2014 by Tara Garnett

From vertical gardens to succulent gardens to community veggie gardens like the San Francisco garden pictured above, city dwellers all around us have started embracing their (hopefully) green thumbs. For urbanites in particular, community gardening provides us with much needed “outside time” with likeminded individuals, with the added gift of hyper-local produce available throughout the growing season. These benefits have led to increases in residential and community garden participation in major cities across the US.

While many people are jumping on the garden-fresh bandwagon to reap the obvious, verdant benefits, it is important to consider the potential side effects that come alongside urban farming. Urban soil is not only closer to possible sources of pollution, like traffic and industrial areas, but could also contain residual chemicals from past land use. Residential land previously occupied by industrial buildings has been found to contain dangerous levels of toxins like lead, which can poison residents and contaminate food grown on-site. But it doesn’t take a former factory to contaminate your backyard. Soil can absorb and hold toxins left over from something as small as a previous homeowners dumping of cleaning water down the drain or off the back porch.

Researchers from Baltimore published an article in PLOS ONE earlier this month assessing Baltimore community gardeners’ knowledge of soil contamination risks and explored what steps can be taken to mitigate the dangers of urban pollution in urban gardens.

The authors, hailing from Johns Hopkins, University of Maryland, and the Community Greening Resource Network, conducted interviews with Baltimore’s community garden members, and found that unfortunately, the gardeners generally seem to have low levels of concern about potential contaminants in their soil. Those working in established community gardens were least concerned as they often assumed that any issues with soil contamination had been addressed in the early days of the garden’s use.

Participants listed lead as the most concerning pollutant—likely due to city interventions concerning lead poisoning—with 66% of surveyed gardeners mentioning it as something that would concern them if found in their soil. The study results also indicate that gardeners are more worried about the presence of pesticides and other added chemicals than most other residual chemicals in the soil. Soil quality and fertility even took greater precedence for some gardeners than the presence of contaminants.

By interviewing Baltimore officials knowledgeable about community gardening practices and soil contamination issues, the researchers determined key steps in assuring the safety of gardening sites. Above all, officials suggested the creation of a central source of information related to soil contamination concerns. Similar projects relating to regulation and urban agriculture are already underway in places like Los Angeles, though these resources aim to help residents navigate the maze of confusing legislation related to urban agriculture, and focus less on providing information on how to evaluate the safety of specific plots of land.

The authors suggest other important ways to determine the safety of a garden site, including learning about the site’s past uses and testing the soil for lingering chemicals, both of which might not seem necessary to those untrained in urban planning or chemical analysis. They also recommend that officials in urban areas provide services that will encourage use of these tools and help gardeners find and interpret the results of soil testing or historical research.

In the meantime, the authors suggest limiting exposure to potentially contaminated land. For instance, we should minimize contact with dirt from garden sites by washing our hands and taking off shoes before entering any indoor spaces. Many interviewed gardeners have tried to mitigate this problem by using raised beds, which they believe eliminates concern about contaminants in homegrown vegetables. However, researchers find this method ineffective, and it should not be seen as a fix-all. Raised beds do not prevent contamination from soil around the beds, which can still be ingested or tracked into the home, and surrounding pollutants have been known to blow into beds or seep into the soil from treated wood used to build the structures.

Urban community gardening is a trend that is here to stay, and we have it to thank for fresher local produce, greener surroundings, a greater sense of community, and for the physical, and sometimes therapeutic, activity it provides. The potential dangers associated with gardening in urban areas probably do not outweigh the benefits, as long as gardeners remain diligent and become better informed. Though their study focused on a limited group, this paper’s findings draw attention to the fact that they’re not. So, next time you’re digging into a grassy patch in your backyard with visions of veggies or working in your local community garden, take a minute to think about what you know about your area, discuss past developments with longtime residents, and above all, clean up afterward.

More information on soil testing and good gardening practices can be found on this site from the EPA.

Citation: Kim BF, Poulsen MN, Margulies JD, Dix KL, Palmer AM, et al. (2014) Urban Community Gardeners’ Knowledge and Perceptions of Soil Contaminant Risks. PLoS ONE 9(2): e87913. doi:10.1371/journal.pone.0087913

Image: Tenderloin People’s Garden by SPUR

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Two Shark Studies Reveal the Old and Slow

Posted on February 11, 2014 by Kayla Graham

Sharks live in the vast, deep, and dark ocean, and studying these large fish in this environment can be difficult. We may have sharks ‘tweeting’ their location, but we still know relatively little about them. Sharks have been on the planet for over 400 million years and today, there are over 400 species of sharks, but how long do they live, and how do they move? Two recent studies published in in PLOS ONE have addressed some of these basic questions for two very different species of sharks: great whites and megamouths.

The authors of the first study looked at the lifespan of the great white shark. Normally, a shark’s age is estimated by counting growth bands in their vertebrae (image 1), not unlike counting rings inside a tree trunk. But unfortunately, these bands can be difficult to differentiate in great whites, so the researchers dated the radiocarbon that they found in them. You might wonder where this carbon-14 (¹⁴C) came from, but believe it or not, radiocarbon was deposited in their vertebrae when thermonuclear bombs were detonated in the northwestern Atlantic Ocean during the ‘50s and ’60s. These bands therefore provide age information. Based on the ages of the sharks in the study, the researchers suggest that great whites may live much longer than previously thought. Some male great whites may even live to be over 70 years old, and this may qualify them as one of the longest-living shark species. While these new estimates are impressive, they may also help scientists understand how threats to these long-living sharks may impact the shark population.

A second shark study analyzed the structure of a megamouth shark’s pectoral fin (image 2) to understand and predict their motion through the water. Discovered in 1976, the megamouth is one of the rarest sharks in the world, and little is known about how they move through the water. We do know that the megamouth lives deep in the ocean and is a filter feeder, moving at very slow speeds to filter out a meal with its large mouth. But swimming slowly in the water is difficult in a similar way flying slowly in an airplane is difficult. Sharks need speed to control lift and movement.

To better understand the megamouth’s slow movement, the researchers measured the cartilage, skin histology, and skeletal structure of the pectoral fins of one female and one male megamouth shark, caught accidentally and preserved for research. The researchers found that the megamouth’s skin was highly elastic, and its cartilage was made of more ‘segments’ than any other known shark, which may provide added flexibility compared to other species. The authors also suggest that the joint structure (image 3) of the pectoral fin may allow forward and backward rotation, motions that are largely restricted in most sharks. The authors suggest that this flexibility and mobility of the pectoral fin may be specialized for controlling body posture and depth at slow swimming speeds. This is in contrast to the fins of fast-swimming sharks that are generally stiff and immobile.

In addition to the difficulties in exploring deep, dark seas, small sample sizes present challenges for many shark studies, including those described here. But whether studying the infamous great white shark or one of the rare megamouths, both contribute to a growing body of knowledge of these elusive fish.

Citations: Hamady LL, Natanson LJ, Skomal GB, Thorrold SR (2014) Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks. PLoS ONE 9(1): e84006. doi:10.1371/journal.pone.0084006

Tomita T, Tanaka S, Sato K, Nakaya K (2014) Pectoral Fin of the Megamouth Shark: Skeletal and Muscular Systems, Skin Histology, and Functional Morphology. PLoS ONE 9(1): e86205. doi:10.1371/journal.pone.0086205

Images1: doi:10.1371/journal.pone.0084006.g001

Image 2: doi:10.1371/journal.pone.0086205.g003

Image 3: doi:10.1371/journal.pone.0086205.g004

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Unearthing the Environmental Impact of Cambodia’s Ancient City, Mahendraparvata

Posted on January 24, 2014 by Samantha Wallace

From the 9^th to the mid-14^th century, the region of Angkor in modern-day northern Cambodia was the capital of Khmer Empire and the largest preindustrial city in the world. Home to possibly more than three quarters of a million people, several different urban plans and reservoir systems, and impressive monuments like the temple of Angkor Wat (pictured from a bird’s-eye-view above), Angkor was the core of the Khmer Empire, which dominated Southeast Asia by the 11^th century CE. Like many modern, booming cities, Angkor was fed by water sourced from another city.

Mahendraparvata, a hill-top site in the mountain range of Phnom Kulen, is significant as the birthplace of the Khmer Kingdom and as the seat of Angkor’s water supply. In 802 CE, Jayavarman II proclaimed himself the universal king of the Angkor region on the top Mahendraparvata. Jayavarma’s ascension to power marked the unification of the Angkor region and the foundation of the Khmer Empire.

Until recently, however, little was known about the urban settlement of Mahendraparvata; a dense forest canopy obscures a great deal of the area’s archaeological landscape. To determine the extent of land use around Mahendraparvata, the authors of a recent PLOS ONE paper examined soil core samples taken from one of the Phnom Kulen region’s reservoirs.

As Angkor’s source of water, Phnom Kulen’s archaeological landscape is littered with hydraulic structures, like dams, dykes, and reservoirs (points A, B, and E on the remote sensing digital image shown below), meant to store and direct Angkor’s water sources strategically. The researchers focused on an ancient reservoir upstream of the main river running north to south, now a swamp, to find evidence of intensive land use.

Core samples taken from the sediment of this ancient reservoir, point F on the image above, provided the researchers with chronological layers of earth containing organic materials, like wood, pollens, and spores, which could be assessed using radiocarbon dating.

By analyzing the sediment cores, researchers found that the reservoir was likely in use for about 400 years. Although the age of the reservoir itself remains inconclusive, sediment samples suggest that the valley was flooded in the mid-to-late 8^th century CE, around the time Jayavarman II unified the area.

The authors found that medium-to-coarse sand deposition in the sediment samples beginning in the mid-9^th century points to the presence of continual soil erosion, either from the surrounding hills or from the dyke itself, likely caused by deforestation in the area. By analyzing samples from the late 11^th century, the authors found that the last and largest episode of erosion occurred, a possible result of intensive land use.

The researchers suggest that deforestation, as evidenced by soil erosion, implies that “settlement on Mahendraparvata was not only spatially extensive but temporally enduring.” In other words, the estimated extent of deforestation by continual sand deposits from the mid-9^th century to the late-11^th century in core samples indicates that Mahendraparvata was home to a large and thriving urban network in need of resources.

However, an increase in pollen spores dated to the 11^th century, followed by the establishment of swamp forests in the early to mid-12^th century in the reservoir, reflects that, by this time, the reservoir had fallen out of use, perhaps linked to changes in water management throughout the broader area, and possible population decline nearby. According to mid-16^th century samples, the swamp flora around this time appears to have developed into the swamp flora seen today in the ruins of Mahendraparvata.

For some 400 years, the Phnom Kulen mountains acted as the main source of water for the Angkor region. The change of water management practices in the Phnom Kulen region has implications for the water supply to Angkor itself. In sum, by examining core samples drawn from one of Phnom Kulen’s ancient reservoirs, authors were able to explore an archaeological landscape that is still largely hidden and a history still mainly obscured by time. The potential link between the rise and fall of urban life in the Angkor region and the use of reservoirs the one used in this study helps to unearth a little bit more about the the Khmer Kingdom and the marked environmental impact of Mahendraparvata.

Citation: Penny D, Chevance J-B, Tang D, De Greef S (2014) The Environmental Impact of Cambodia’s Ancient City of Mahendraparvata (Phnom Kulen). PLoS ONE 9(1): e84252. doi:10.1371/journal.pone.0084252

Image 1: Angkor Wat by Mark McElroy

Image 2: journal.pone.0084252

Image 3: journal.pone.0084252

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Rainforest Fungi Find Home in Sloth Hair

Posted on January 18, 2014 by Kayla Graham

Most of us have seen a cute sloth video or two on the Internet. Their squished faces, long claws, and scruffy fur make these slow-moving mammals irresistible, but our furry friends aren’t just amusing Internet sensations. Like most inhabitants of the rainforest, little is known about the role sloths play in the rainforest ecosystem.

Three-toed sloths live most of their lives in the trees of Central and South American rainforests. Rainforests are some of the most biodiverse ecosystems in the world and home to a wide variety of organisms, some of which can be found in rather unusual places.

Due to their vast biodiversity, rainforests have been the source for a wide variety of new medicines, and researchers of this PLOS ONE study sought to uncover whether sloth hair may also contain potential new sources of drugs that could one day treat vector-borne diseases, cancer, or bacterial infections. Why look in sloth fur? It turns out that sloths carry a wide variety of micro- and macro-organisms in their fur, which consists of two layers: an inner layer of fine, soft hair close to the skin, and a long outer layer of coarse hair with “cracks” across it where microbes make their homes. The most well-known inhabitant of sloth fur is green algae. In some cases, the green algae makes the sloth actually appear green, providing a rainforest camouflage.

In the study, seventy-four separate fungi were obtained from the surface of coarse outer hair that were clipped from the lower back of nine living three-toed sloths in Soberanía National Park, Panama, and were cultivated and tested for bioactivity in the lab.

Researchers found a broad range of in vitro activities of the fungi against bugs that cause malaria and Chagas disease, as well as against a specific type of human breast cancer cells. In addition, 20 fungal extracts were active in vitro against at least one bacterial strain. The results may provide for the first time an indication of the biodiversity and bioactivity of microorganisms in sloth hair.

Since sloths are moving around in one of the most diverse ecosystems in the world, it’s possible that they may pick up “hitchhikers,” so the researchers can’t be sure how these fungi came to live on the sloth fur. They may even have a symbiotic relationship with the green algae. However the fungi ended up in the fur, the authors suggest their presence in the ecosystem provides support for the role biodiversity plays both in the rainforest and potentially our daily lives.

Citation: Higginbotham S, Wong WR, Linington RG, Spadafora C, Iturrado L, et al. (2014) Sloth Hair as a Novel Source of Fungi with Potent Anti-Parasitic, Anti-Cancer and Anti-Bacterial Bioactivity. PLoS ONE 9(1): e84549. doi:10.1371/journal.pone.0084549

Image: Bradypus variegates by Christian Mehlführer

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New Year, New Species

Posted on January 10, 2014 by Megan Edwards

Rock lizards, pigment producing fungus, eagle rays, ant garden parasites, and Antarctic sea anemones: new species are discovered all the time and there are likely still millions that we simply haven’t yet discovered or assessed. Species are identified by researchers using a range of criteria including DNA, appearance, and habitat. PLOS ONE typically publishes several new species articles every month, and below we are pleased to help introduce five that were discovered in 2013.

Iranian Rock Lizards

Thought previously to consist of only three species, this group of lizards are now seven distinct species. They appear very similar to one another, making it difficult to tell which characteristics define different species, and which are just variations present in the same species. They also have a variety of habitats, from trees to rocky outcrops, and the genus is widespread. Iranian, German, and Portuguese scientists used genetic variation and habitat to help describe four new species of Iranian rock lizards, Darevskia caspica, D. Kamii, D. kopetdaghica, and D. schaekeli. These techniques, in addition to analysis of the the lizards’ physical features, as in the photo of the four new species’ heads at the top of this page, helped to identify them definitively.

Pigment producing fungus

Found in soil, indoor environments, and fruit, Talaromyces atroroseus produces a red pigment that might be good for manufacturing purposes, especially in food. Some other species of this type of fungus produce red pigments, but they are not always as useful because they can also produce toxins. T. atroroseus produces a stable red pigment with no known toxins, making it safer for human use, according to the Dutch and Danish researchers who identified it.

Naru eagle ray

Fish, like rays and sharks, are at high risk for extinction as a group, but as rare as they are, they can be plentiful enough in some locations to make them undesirable to locals. The discovery of the Naru eagle ray, Aetobatus narutobiei, splits a previously defined species, A. flagellum, that, due to its shellfish-eating habits, is considered a pest and culled in southern Japan. The discovery by Australian and Japanese scientists that this species is actually two species prompted the authors to encourage a reassessment of the conservation status of the rays.

eagleray.0083785.g004

Fungal parasites in ant gardens

In the Brazilian rainforest of Minas Gerais, leafcutter ants cultivate fungus, their primary source of food, on harvested leaf clippings. But scientists from Brazil, United Kingdom, and The Netherlands have discovered that their food source is threatened by four newly identified mycoparasites, Escovopsis lentecrescens, E. microspora, E. moellieri, and Escovopsioides nivea. The parasites grow like weeds in the ants’ gardens, crowding out more desirable fungus used for food. Unfortunately for the ants, researchers expect there are many similar unidentified species yet to be discovered.

Antarctic sea anemone

Living on the previously undocumented ecosystem of the underside of the Ross Ice Shelf in Antarctica, American researchers discovered the first species of sea anemone known to live in ice, Edwardsiella andrillae. Fields of anemone were discovered using a scientist-driven remote-controlled submersible. The anemone burrows and lives within the ice and dangles a tentacle into the water beneath, almost as if it is dipping a toe in the water to test the chilly temperature.

Look here to read more about new species.

Citations

Ahmadzadeh F, Flecks M, Carretero MA, Mozaffari O, Böhme W, et al. (2013) Cryptic Speciation Patterns in Iranian Rock Lizards Uncovered by Integrative Taxonomy. PLoS ONE 8(12): e80563. doi:10.1371/journal.pone.0080563

Frisvad JC, Yilmaz N, Thrane U, Rasmussen KB, Houbraken J, et al. (2013)Talaromyces atroroseus, a New Species Efficiently Producing Industrially Relevant Red Pigments. PLoS ONE 8(12): e84102. doi:10.1371/journal.pone.0084102

White WT, Furumitsu K, Yamaguchi A (2013) A New Species of Eagle RayAetobatus narutobiei from the Northwest Pacific: An Example of the Critical Role Taxonomy Plays in Fisheries and Ecological Sciences. PLoS ONE 8(12): e83785. doi:10.1371/journal.pone.0083785

Augustin JO, Groenewald JZ, Nascimento RJ, Mizubuti ESG, Barreto RW, et al. (2013) Yet More “Weeds” in the Garden: Fungal Novelties from Nests of Leaf-Cutting Ants. PLoS ONE 8(12): e82265. doi:10.1371/journal.pone.0082265

Daly M, Rack F, Zook R (2013) Edwardsiella andrillae, a New Species of Sea Anemone from Antarctic Ice. PLoS ONE 8(12): e83476. doi:10.1371/journal.pone.0083476

Figures are all from their respective articles.

The post New Year, New Species appeared first on EveryONE.

Awkward Silences: Technical Delays Can Diminish Feelings of Unity and Belonging

Posted on December 17, 2013 by Megan Edwards

Smooth social interaction is fundamental to a sense of togetherness. We’ve all experienced disrupted conversations—some caused by human awkwardness and others by breakdowns in technology. The content of our interactions does influence our connection to each other, but the form and process of communication also play a role. Technical delays that occur below our conscious detection can still make us feel like we don’t quite click with the person we are trying to communicate with. The authors of a recently published PLOS ONE article, funded by a Google Research Award, investigated how delays introduced into technologically mediated conversations affected participants’ sense of solidarity with each other, defined as unity, belongingness, and shared reality.

For this research, conducted at University of Groningen, The Netherlands, participants in three sets of experiments sat in cubicles with headsets connected to computers (conditions that many of us with desk jobs can relate to) and were asked to talk about holidays for five minutes with an assigned partner. Some conversations were uninterrupted. Others were manipulated by introducing a one-second auditory delay. Some pairs knew about the delay and others did not. Afterward, the conversationalists completed a questionnaire about their sense of unity, belonging, understanding, and agreement with their partners.

Researchers found that those participants whose conversations were interrupted expressed significantly diminished feelings of unity and belonging. Awareness of technical problems had no apparent effect on perceived solidarity. Even acquaintances stated that they felt a disconnect, though to a lesser degree, than participants who did not know each other. Despite participants expressing that they felt less unity and belongingness with their partner even when they had the opportunity to attribute it to technical problems, technology did not get a free pass on the delayed signal. Those with an interrupted connection also expressed less satisfaction with the technology. Points may have been lost for both relationships and telecommunications.

In a world where our interactions are increasingly mediated by computers and mobile phones with less than perfect signals, the authors suggest that this research provides insight into how our daily interactions may be affected. The method of communication we choose may influence our personal and business relationships, especially among strangers. The authors also posit that technology meant to improve long distance communication by imitating face-to-face interaction may not measure up to expectations if it is not executed without interruptions or delays. Perhaps this is something to consider during your next awkward phone call or video conference— though your awareness of technology as a possible barrier ultimately may not make a difference in how you perceive the person on the other end of the line.

Citation: Koudenburg N, Postmes T, Gordijn EH (2013) Conversational Flow Promotes Solidarity. PLoS ONE 8(11): e78363. doi:10.1371/journal.pone.0078363

Images: First image by Villemard is in the public domain. Second image is Supplemetary Figure 1 from the article.

Mama Gorilla Knows Best

Posted on December 9, 2013 by Tara Garnett

While few question the importance of maternal care in humans, scientists do question the influence of a mother’s behavior in other species. Researchers from the Max Planck Institute for Ornithology have now published an article in PLOS ONE showing exactly how important a mother’s guidance can be to our friend the western lowland gorilla. After monitoring the spread of two specific behaviors in captive groups of gorillas, the authors suggest that gorilla mothers play a vital role in social learning and the transmission of behaviors between generations.

The authors videotaped gorilla behavior for 4-6 hours per day over the course of eight weeks in 2000 and 2010 at Howletts Wild Animal Parks. Throughout their sittings, they watched for two specific behaviors shown by different individuals: the “Puff-Blowing” technique, used during mealtimes to separate oat from chaff, and the “Throw-Kiss-Display,” one male gorilla’s coy way of drawing visitors’ attention to him. Check out the live-action versions in the videos below.

During the initial observational period in 2000, the “Puff-Blowing” technique was used by three adult females, while the “Throw-Kiss-Display” was implemented by a single silverback male, Kouillou, and no other members of the group.

By the time the researchers returned in 2010, the “Puff-Blowing” technique was practiced by 15 individuals, while the “Throw-Kiss-Display” had been dropped entirely, even by the original practitioner.

When the researchers analyzed the data, they found that the spread of the observed “Puff-Blowing” technique to new gorillas could be tracked through mother-child relationships. All but three offspring (13 total) of the original three mothers used the technique. Furthermore, this behavior was never seen in the offspring of mothers who did not perform the technique.

Based on their observations, the authors suggest that the actions of the gorilla mother play a major role in the transmission of behaviors. In other words, baby gorilla see, baby gorilla do. While the authors mention that “Puff-Blowing” may be more likely to be passed down because it’s useful at mealtime—unlike the “Throw-Kiss-Display”—they argue that the path of transmission (mother-offspring) is significant. The authors also indicate that genetic factors may affect the occurrence of these behaviors, as not all offspring of the “Puff-Blowing” mothers inherited the action, suggesting that other forces may be at play.

Lesson learned: Even gorillas need their mommies.

For more evidence of the importance of mothers in the animal kingdom, check out this paper on migration patterns in humpback whales.

Citation: Luef EM, Pika S (2013) Gorilla Mothers Also Matter! New Insights on Social Transmission in Gorillas (Gorilla gorilla gorilla) in Captivity. PLoS ONE 8(11): e79600. doi:10.1371/journal.pone.0079600

Image Credit: USINFO Photo Gallery

Videos: S1 and S2 from the paper

Snail Mucus May Alter Plant Defenses

Posted on December 6, 2013 by Kayla Graham

Predator-prey relationships make up a large part of the food chain, and both predators and prey have developed visual, auditory, physical, and even chemical abilities to better their respective chances for surviving, whether that means catching a meal or avoiding turning into one. Ants may mimic spiders to avoid predators and a grizzly bear’s size and strength allow them to feast on pretty much anything. But what about the interactions between a slow-moving predator, like the garden snail pictured above, and completely stationary “prey,” like a plant?

Garden snails are found throughout the world and feast on many species of plants, including those in our gardens. One of those species is the black mustard plant. Originally from the Mediterranean, black mustard is now common throughout the world. Scientists are working to understand if a common plant, like black mustard, may be able to pick up chemical signals from snail mucus called kairomones and preemptively change their biochemistry to become less appealing to snails. Snails produce mucus during motion, and its presence is often a good indicator to plants that a snail is nearby.

In a recent article published in PLOS ONE, a researcher from the Department of Zoology at the University of Wisconsin-Madison studied whether “unwounded” black mustard plants exposed to snail mucus before being exposed to actual snails experienced lower rates of snail predation.

The researcher exposed black mustard plants at different ages to snail mucus, collected on paper, when the plant was a seed, a seedling, or when it was a seed and again when it was a seedling. The control plant group was not exposed to mucus at any point. After plants were exposed to one of these treatments, a single adult garden snail was then placed with one of the plants to measure if the snail would munch on each plant equally.

Plants that received early exposure or a repeated exposure to mucus during the seedling stage showed a reduced susceptibility to snail feeding or “attack,” but plants in the control group experienced no significant reduction in feeding. The author suggests that plants may pick up on chemicals associated with plant eaters—in this case snail mucus—that may prompt them to become less appealing before an initial attack even occurs.

Although the chemical mechanism that the plants used to make themselves less appealing isn’t clear, in this predator-prey-like interaction, the predators may actually be inadvertently making their dinner less appealing. Turns out gardeners aren’t the only ones that don’t like slimy snail trails.

Citation: Orrock JL (2013) Exposure of Unwounded Plants to Chemical Cues Associated with Herbivores Leads to Exposure-Dependent Changes in Subsequent Herbivore Attack. PLoS ONE 8(11): e79900. doi:10.1371/journal.pone.0079900

Image: Garden Snail by Michael Gwyther-Jones

Robofish: How Color and Tail Wagging Helped Bring a Robot Fish to “Life”

Posted on November 21, 2013 by Souri Somphanith

In an age of 3D printing and bionic limbs, distinctions between the manmade and the natural can sometimes blur. Take, for example, the case of the robotic fish depicted above (part A). This little guy is modeled after Notemigonus crysoleucas (image, part B), also known as the golden shiner, and in a recent PLOS ONE study, researchers put it to the test: can a robotic fish influence the behavior of a real fish, and if so, what characteristics enable the robotic fish to do so? According to the researchers at Polytechnic Institute of New York University, answers may depend on the robot fish’s color and the frequency with which it waggles its tail.

To find out more, the authors commissioned the making of two robot fish for this study: one gray and one red. While both physically modeled the golden shiner in many respects, only the gray robot fish was painted to mimic its real-life counterpart. Other than color, the two robots were identical: both consisted of three rigid parts, connected on hinges, and sported silicone tail fins.

As illustrated above, one robot fish was placed in a water tunnel with a real fish during each trial. The real fish was free to swim in the tunnel while the robot fish “swam,” or waggled its tail fin, in the center of the apparatus. The robotic fish’s tail waggled at various frequencies, ranging from 0 Hz to 4 Hz, as webcams tracked the real fish’s movements. The middle of the tunnel was designated the “focal region” to indicate where fish and robot interaction was likely to occur. The researchers further divided the region behind the fish into four parts, explaining that the robot fish’s tail wagging was likely to affect the water flow, and thus the real fish’s behavior, in this area.

After reviewing the webcam footage, they found that neither factor (color, tail wagging frequency) working alone had a significant impact on the real fish’s swimming behavior. However, when the gray robot wagged its tail at 3 Hz, the real fish spent a significantly longer time swimming in the center of the tunnel, preferring to spend most of its time swimming right behind the robot. When this happened, the wake created by the robot’s tail wagging could allow the real fish to reduce its energy expenditure while swimming.

What’s so special about wagging your tail fin at 3 Hz, you ask? The researchers ascertained through preliminary research that when golden shiners swim, their tails waggle at 3.32 Hz. In addition, the gray robot’s coloring may have been more attractive to the golden shiner than the red robot’s, as it may have elicited a likeness-related social response in the real shiner. This suggestion is in line with other robot work in comparable fish species.

In other words, the robot fish exerted the most influence—or was the most convincing to the real fish—when its coloring and movements closely corresponded to the coloring and movements of a real fish. Go figure!

If you are interested in learning more, visit our website and see what others had to say.

Citation: Polverino G, Phamduy P, Porfiri M (2013) Fish and Robots Swimming Together in a Water Tunnel: Robot Color and Tail-Beat Frequency Influence Fish Behavior. PLoS ONE 8(10): e77589. doi:10.1371/journal.pone.0077589

Image 1: Figure 1 from the paper

Image 2: Figure 2 from the paper

Image 3: Figure 4 from the paper

Biking the Distance… In 30 Minutes or Less: The Impact of Cost and Location on Urban Bike Share Systems

Posted on November 19, 2013 by Samantha Wallace

Those of us who commute to the PLOS San Francisco office have noticed the emergence of bike share stations cropping up along the San Francisco Bay and on the city’s main drag. And we’re not alone here in San Francisco: the picture above is from the New York City Department of Transportation’s bike share. Around the world, bike share systems, which aim to make bicycles available on a short-term basis to anyone, have experienced massive growth as cities work to decrease gas emissions and encourage people to stay active. However, not everyone is ready to forgo the convenience of four wheels for two just yet. To understand why more people haven’t made the switch from cars to bike share systems, the author of a recently published PLOS ONE paper delved into possible factors affecting our willingness to don a helmet and cycle the distance.

Using publically available data from Washington DC and Boston, Dr. Jurdak, an Australian researcher, conducted a series of statistical analyses designed to examine the impact of bike share system pricing and neighborhood layout on potential bikers. It turns out cost is a major factor for commuters and tourists alike, but distance is not. Although analyses showed a bias towards shorter trips with a tendency towards a peak of 6 minutes—averaging 13 minutes per trip—a sharp drop off occurred in the likelihood of trips right around 30 minutes.

Why the decline at around 30 minutes? In both Boston and Washington DC, trips under 30 minutes incurred no additional cost in the bike share pricing system. Registered users of the bike share, typically commuters, must pay an initial registration fee but have a grace period for all trips completed in less than 30 minutes. Trips extending beyond 30 minutes, however, incur additional fees. In other words, public bicyclers are looking to maximize the distance biked and time spent without incurring any additional cost. Researchers have labeled this as ‘cost sensitivity.’

Statistical analyses also demonstrated the same cost sensitivity in casual users, or those who do not have a monthly or annual membership, and who likely use the bike share system for tourism. However, instead of noting a decline in the likelihood of trips around 30 minutes, Dr. Jurdak found a decline for casual users at around 60 minutes (another price point).

On the other hand, despite sensitivity to cost, bikers appeared less dissuaded from bike trips based on neighborhood layout. Although stations in Boston were on average much closer to other nearby stations than in Washington DC, in general, the trip distribution for both cities was remarkably similar. Perhaps not surprisingly, the most popular routes taken in both Boston and Washington DC were relatively flat.

To encourage more people to cut the car usage and grab a rental bike, Dr. Jurdak recommends that cities consider incentivizing their constituents with what they care about: cost. Modified prices for bike rental during peak hours may decrease car traffic on congested roads; an extension of grace periods for biking difficult topology, like up a steep San Francisco hill, might encourage us to bike even though the clock is ticking to 30 minutes and an incurred rise in price. As cities look to evolve public transportation systems and increase responsible urban mobility, and as city dwellers look for cost-effective ways to get around, bike share programs continue to offer healthy solutions for all, even at 30 minutes or less.

For more on the effects bike share systems are having around the world, check out another recent PLOS ONE paper and the researchers’ blog post on bike webs, visualizations of bike share schemes.

Citations:

Jurdak R (2013) The Impact of Cost and Network Topology on Urban Mobility: A Study of Public Bicycle Usage in 2 U.S. Cities. PLoS ONE 8(11): e79396. doi:10.1371/journal.pone.0079396

Image 1: Citi Bike Launch by New York City Department of Transportation

A Rat’s Journey Through Virtual Reality

Posted on November 11, 2013 by Kayla Graham

Few ideas excite the imagination more than virtual reality. We humans use virtual reality for training, entertaining, and even education, but we can also use it to study human and animal behavior. Adaptive behavior, or the ability to adjust to new situations, is influenced by what we see, hear, and experience in our environment; unfortunately, for this reason, it is difficult to isolate the possible stimuli that affect it. The authors of this recently published PLOS ONE paper developed a virtual reality environment to try to isolate and measure the impact of visual and sound cues on rats navigating through a virtual space.

The virtual reality navigation test is based on an experiment called the Morris Water Maze, a standard lab test where a rat swims through water using visual cues on the walls to navigate. The virtual version uses a 14 square-foot room with visual cues projected on each wall and sounds from 4 sides (pictured above). The rat is at the center of the room, wearing a harness (pictured on the right) on a spherical treadmill placed on a three-foot circular table.

Before beginning the navigation tasks, researchers trained nine male rats to move in virtual reality. The rat started from one of 4 random start locations, facing the wall (see video below). The northeast quadrant of the space was designated as the ‘reward zone,’ indicated by a white dot. Upon entry to this zone, the rat was rewarded with sugar water (if only all video games worked this way).

After training, the researchers tested each rat’s ability to navigate to the reward zone using one of three cues: audiovisual, visual, or auditory. Once the rat found the reward zone, a 2-second blackout period was initiated, and then the rat was ‘moved’ back to one of the 4 random start locations. The video below shows the visual cue test.

Scientists found that rats can learn to navigate to an unmarked location based on visual cues—with a moderate amount of training. However, the rats were unable to use the auditory cues to navigate to the reward zone, and instead moved in circles to try to locate it.

Although the rat’s harness may look a little funny, it is a relatively noninvasive test, and since the animal is not in water, like in the Morris Water Maze test, it is easier to combine this test with tools to measure neural and physical variables in the task. Additionally, the virtual maze may contribute to new methodology evaluating the underlying factors in adaptive behavior, specifically because no other cues besides the audiovisual, visual, and auditory defined the spatial location of reward, something that is difficult to achieve in the real world. Despite humans not yet understanding what virtual reality means to us, we can already use it to better understand animal learning and behavior.

Citation: Cushman JD, Aharoni DB, Willers B, Ravassard P, Kees A, et al. (2013) Multisensory Control of Multimodal Behavior: Do the Legs Know What the Tongue Is Doing? PLoS ONE 8(11): e80465. doi:10.1371/journal.pone.0080465

Image 1: doi:10.1371/journal.pone.0080465

Image 2: doi:10.1371/journal.pone.0080465

Video 1: doi:10.1371/journal.pone.0080465

Video 2: doi:10.1371/journal.pone.0080465

Spotlight on PLOS ONE’s NeuroMapping and Therapeutics Collection

Posted on November 9, 2013 by PLOS Collections

Launched in 2010, the Neuromapping and Therapeutics Collection is a unique collaboration between PLOS ONE and the Society for Brain Mapping and Therapeutics. The Neuromapping and Therapeutics Collection provides a forum for interdisciplinary research aimed at translation of knowledge across a number of fields such as neurosurgery, neurology, psychiatry, radiology, neuroscience, neuroengineering, and healthcare and policy issues that affect the treatment delivery and usage of related devices, drugs, and technologies. The Collection is open to submissions on these topics from any researcher—so far, 24 research papers have been published as part of this Collection.

We spoke to Dr. Allyson Rosen, one of the members of the Society for Brain Mapping and Therapeutics who helps coordinate the Neuromapping and Therapeutics Collection, to discuss the latest news and research in this area, and the new submissions to the collection they’re hoping to see in the next few months:

What’s exciting in Neuromapping and Therapeutics at the moment?

It is exciting to see how creative scientists and clinicians are at solving important clinical problems by combining diverse techniques in innovative ways. We see our collection as a home for cross-disciplinary work that might not “fit” in traditional journals. For example, we have published MR methods to enable effective brain infusions and work that exploits computer-aided design for cranial reconstructions. There are invasive and non-inva

What are the implications of President Obama’s commitment to Human Brain Mapping research?sive techniques for stimulating selective brain regions and creating focal lesions, such as transcranial magnetic stimulation, transcranial Doppler technology, and X-ray microplanar beam technology. There are also innovative analysis techniques that exploit powerful computational methods that were previously unavailable.

Given the high-profile nature of the Brain Mapping Initiative and the state of the US economy, we have advocated that there be some clinical implications to the announcement. We believe that this approach will ensure continued public support at a time of great need and uncertainty.

Are there any specific research areas where you’d like to see more submissions to the Collection?

We are proud of the work we’ve received and deeply impressed with the broad array of papers submitted so far. This is a testament to the creativity of our contributors, and we welcome their diversity. We particularly welcome work presented at the international meeting of the Society for Brain Mapping and Therapeutics that occurs in the spring of each year.

Why do you think it’s important to publish this kind of research in an open access journal such as PLOS ONE?

Our society is committed to being inclusive and welcoming any profession that seeks to improve the health and wellbeing of patients with brain disorders. An open access journal enables easier promotion of work we feel is important and encourages sharing among diverse disciplines. Often, truly cutting-edge work is so far ahead of its time that there is not yet an appreciation for its importance. Often, clinical problems are seen as practical but not necessarily novel. We appreciate the mission of PLOS ONE as upholding strong scientific integrity and not as triaging work based on arbitrary decisions regarding importance.

Come visit us at SFN 2013.

Both the Society for Brain Mapping and Therapeutics and PLOS ONE will be attending SFN 2013 – please drop by booth #136 to say hello and learn more about the Collection. For instructions on how to submit to the Collection, please visit the Collection page and download the submission document.

If you have any questions about this Collection, or any other PLOS Collections, please email collections@plos.org

Image credit for Collection cover: Alka Joshi

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