80beats » Living World

Zebra Stripes: Fashion Statement or Fly Repellant?

Veronique Greenwood — Fri, 10 Feb 2012 17:35:19 +0000

Why’d the zebra evolve its stripes? Perhaps because stripes seem to keep off horseflies, a new study suggests. There’s good evolutionary reason to escape the ravages of horseflies, at least for horses and their relatives; though flies are just annoying pests from the human perspective, horsefly-bitten horses can grow skinny and have trouble producing milk for their young. And as soon as baby-making is affected by something in the environment, adaptation isn’t far behind.

Other research has shown that horseflies prefer to land on black horses instead of white, which got Gabor Horvath, author of the recent study, thinking about how they’d react to black-and-white specimens, such as zebras. Of course, actual zebras can be hard to experiment on, as The Economist notes in an article on the research:

[Real zebras] insist on moving around and swishing their tails. The team therefore conducted their study using inanimate objects. Some were painted uniformly dark or uniformly light, and some had stripes of various widths. Some were plastic trays filled with salad oil (to trap any insect that landed). Some were glue-covered boards. And some were actual models of zebra. They put these objects in a field infested ...

Video: Coral’s Dramatic Yet Slo-Mo Emergence From the Sea Floor

Sarah Zhang — Thu, 09 Feb 2012 19:05:20 +0000

It’s just a pile of sand–no wait, is that a tentacle wriggling in the corner? These time-lapse videos taken by researchers at the University of Queensland show that mushroom corals unearth themselves by slowly inflating and then deflating over 10 to 20 hours. See a second coral attempt the same after the jump.

It’s a Shark-Eating Shark–Eating–Shark World

Veronique Greenwood — Thu, 09 Feb 2012 17:02:08 +0000

Om nom nom…oh, you caught me in the middle of dinner!

While conducting a survey of fish in an area of the Great Barrier Reef, scientists stumbled upon this little tableau: a tasselled wobbegong, or “carpet shark,” in the midst of devouring a brown-banded bamboo shark. (Either that, or they’re just sharing a very intense kiss.) The carpet shark, which hides in the sand and springs out at its prey, has never been photographed eating another shark before, though scientists could tell from poking around in their stomach contents that their distant cousins were sometimes on the menu. Carpet sharks seem to be slow eaters, though: the team hung around for a full 30 minutes to see if it would suck in more of the bamboo shark, but to no avail.

Maybe it just has stage fright.

Images courtesy of Tom Mannering and the journal Coral Reefs

Watch Ants Sip Grenadine, Spheres of Algae Spin, and Other Small-Scale Spectacles in These Movies

Valerie Ross — Tue, 07 Feb 2012 20:20:11 +0000

The many-times-magnified photos of the Nikon Small World photomicrography contest entrance us year after year, with mesmerizing close-ups of nature’s microscopic marvels. Now, in the first Small World in Motion movie competition, we get to see the world’s wee wonders in action. The three winning films and eleven honorable mentions chronicle circulating blood, budding yeast, gestating eggs, and more.

First Place: This time-lapse video, at 10x magnification, traces the path of ink injected into an artery of a three-day-old chick embryo. As the ink spreads through the chick’s vascular system, the branching blood vessels and beating heart become clearly visible.

Second Place: Mitochondria (in blue), the power plants of animal cells, move through the nerve cells (in green) of a transgenic zebrafish. This film, at 40x magnification, is the first time mitochondria have been watched shuttling through nerve cells in a living vertebrate, says its creator Dominik Paquet.

Third Place: A daphnia, a type of small crustacean, turns its compound eye towards a tiny sphere of Volvox algae, at 50x magnification. The scientist who made the video found these organisms in water from his garden pond.

Honorable Mention: An ant colony devours a drop of grenadine in this time-lapse video.

Watch the rest of the runners ...

Audio: Ancient Katydid Sings From Beyond the Grave

Veronique Greenwood — Tue, 07 Feb 2012 17:46:51 +0000

Above, the fossilized teeth running along the katydid’s left and right wings
that researchers used to reconstruct the creature’s call.

Well-preserved fossils can tell paleontologists myriad things, such as what color feathers dinosaurs had, how ancient spiders evolved, and what kind of microbes were around 3 billion years ago. The latest such revelation is rather whimsical, as well as being scientifically interesting. Scientists have been able to reconstruct the chirping of a Jurassic ancestor of modern katydids by examining the wings of an exquisitely preserved fossil specimen.

Katydids create their song by scraping one wing across the other, running a hard ridge of tiny teeth, like those on a comb, across the ridge on the opposite wing. The research team examined the size and shape of the teeth on the wings of Archaboilus musicus, as the Jurassic specimen is called, to come up with an estimate of the frequency of the sound that such scraping would have produced. They found that the resulting chirping would have fallen at 6.4 kilohertz, within the range of normal human hearing.

So, if you ever get the chance to travel back 165 million years, keep your ...

Does a Chinese Boy Really Have “Cat Eyes” That See in the Dark?

Sarah Zhang — Thu, 02 Feb 2012 23:23:09 +0000

The strangest thing about this Chinese boy’s light blue eyes is not their color. It’s the purported fact that he can see in the dark. His eyes are just like cat eyes, glowing blue-green when you shine a light in them, says this clip from China’s state-run English TV channel. The boy can catch crickets in the dark without a flashlight and even completes a writing test in a pitch-black stairwell. True, or too good to be?

Natalie Wolchover at Life’s Little Mysteries has rounded up some experts and their collective reaction seems to be, “Hmm…” (It doesn’t help that this video has been posted on YouTube under the name, “Alien Hybrid or Starchild Discovered in China? 2012.”) One possibility they consider is whether the boy has a mutation that produced something like a tapetum lucidum, an extra layer of tissue that helps cats see in the dark. James Reynolds, a pediatric ophthalmologist at State University of New York in Buffalo, puts a stop to that idea:

[T]here is no single genetic mutation that could produce a fully formed and functioning tapetum lucidum, Reynolds explained; such an ability would require multiple mutations, which wouldn’t occur all at once. Evolution happens incrementally, ...

How Spider Silk’s Molecular Make-up Lets It Morph

Veronique Greenwood — Thu, 02 Feb 2012 21:06:48 +0000

What’s the News: The surprising strength of spider silk has fascinated scientists (and everyone else) for years: it’s stronger than steel, yet incredibly flexible. A new paper gives some delicious details that explain how, exactly, spider silk has such superpowers.

Go With the Flow, Then Stay Strong: The strand of silk that a spider hangs from can stretch to double its usual length. But then, after that virtuosic show of elasticity, it turns rigid.

The reason for that, this team found previously, is that on the molecular level, spider silk is made of scrunched-up proteins that are pulled straight as the silk stretches. But once they’ve been fully unfurled, the proteins lock into a new, stiff pattern called a beta-sheet nanocrystal. For a spider, having the molecules snap to stiffness after stretching is probably analogous to a rock climber arresting a rappel by clipping the end of her rope in place.

Breezy Bulkheads: In their current study using real-life spider webs and computer models, the team found that when a gentle force like a breeze is broadly applied to a spider web, the whole thing stretches and elongates. But yank or push more forcefully on one part ...

Getting Big Takes Time…Millions and Millions of Generations, Say Biologists

Veronique Greenwood — Tue, 31 Jan 2012 20:21:05 +0000

Creatures as large as elephants are unusual; it takes a long time to evolve such size.

How long does it take for a mammal as small as a mouse to evolve into something as large as an elephant? A really, really long time, a recent study has found: about 24 million generations, at minimum.

To get that number, researchers looked at the evolution of body mass over the last 70 million years, after the dinosaurs went extinct and surviving animals expanded into the ecological niches they left behind. That estimate is far longer than earlier estimates, which, extrapolating from bursts of super-fast evolution in mice, range from just 200,000 to 2 million generations. Such speedy evolution, in actuality, is probably not sustainable over the long term—hence the lengthy new estimate.

Getting smaller, on the other hand, is a much shorter process, happening up to 30 times faster. Evolving to a smaller size might be easier because smaller animals reach reproductive maturity more quickly, the researchers suggest. Or it could reflect the greater availability of ecological niches for tiny organisms: a scrap of grassland can feed a fieldmouse, but an elephant needs acres. Certain physical constraints—the pull of ...

How Do Females Keep Sperm Fresh for Years?

Veronique Greenwood — Tue, 31 Jan 2012 16:04:34 +0000

The researchers chose to examine the sperm of crickets, because, as with humans, you can get samples of it without having the male come into contact with a female first.

What’s the News: You might already know that sperm, which can survive for only a few hours when exposed to the outside world, can live for several days in women after ejaculation. But did you know that an ant queen can fertilize her eggs with sperm she’s stored for up to 30 years? And that organisms as diverse as birds, reptiles, and insects can hang onto sperm and keep it fresh for days, weeks, or months?

Scientists studying this ability have been trying to figure out how females do it, and in a recent paper, researchers put forth evidence showing that the ladies may be arresting the aging process, by slowing down sperms’ metabolism.

How the Heck:

The researchers, who hail from the University of Tuebingen in Germany and University of Sheffield in the UK, decided to test one of the current models of cellular aging with sperm. This model proposes that the reason cells age is that as they go about their daily business ...

Ancient Tulip-like Creatures Discovered in the Burgess Shale

Veronique Greenwood — Fri, 20 Jan 2012 20:22:14 +0000

Tulips in the rocks.

Artist’s conception of what the living creatures would have looked like.

The Burgess Shale fossil beds in the Canadian Rockies are famous for showing us some of the creepiest evolutionary dead-ends to ever grace the planet. They conjure up underwater scenes of many-legged spiky creatures scuttling beneath gigantic spider shrimp, but a recent find in the Burgess Shale suggests a more pastoral landscape: fields of waving tulip-shaped creatures, each about 8 inches high.

These newly discovered filter feeders, named Siphusauctum gregarium by their discoverers, have been found in clumps of over 65, and appear to have fed by sucking water through their bodies and extracting food particles.

Images courtesy of Royal Ontario Museum and Marianne Collins.

[via ScienceDaily]

Captive Cheese Fungus Gobbles Up Spills, Forming a Living, Self-Cleaning Surface

Veronique Greenwood — Tue, 10 Jan 2012 18:11:21 +0000

How a living material of cheese fungi sandwiched between plastic sheets works.

The crusty rind of cheeses like Camembert provide more than texture: they are miniature fortress walls, made of fungus, that protect the cheese’s creamy insides from bacterial invasions. Now, taking inspiration from this delicious snack, chemical engineers at ETH Zurich in Switzerland have shown that such a fungus can be enclosed in porous plastic and will digest spills, with implications for creating antibacterial surfaces from living material.

The team sandwiched a layer of Penicillium roqueforti—from, you guessed it, Roquefort cheese—between a plastic base and a top sheet of plastic with nanoscale pores that allowed gas and liquids to move through, but did not allow the fungus to spread. Then, they mimicked a kitchen spill by pouring sugary broth on the surface and watched as, over the course of two weeks, the captive fungus gradually consumed the entire spill, leaving the surface clean. As shown in the figure above, the fungi can go dormant when there is no food around, so if one had a countertop of such a material, you wouldn’t need to keep spilling sugar on it to keep the fungi happy. ...

Bacteria Survive in Cold, Dry, Mars-like Conditions By Living Off Iron

Valerie Ross — Wed, 04 Jan 2012 19:09:06 +0000

An image of the Martian surface from NASA’s Viking 2

To eke out even the barest subsistence on Mars, a living thing would have to adapt to a formidable set of environmental challenges: an arid, often extremely cold landscape with miniscule amounts of oxygen in the atmosphere and no organic matter to eat. During a recent foray into a similarly inhospitable part of our own planet, scientists have discovered several species of bacteria that hint at what life on Mars, if it exists, might look like. These microbes survive on minerals in the surrounding rocks—minerals also found in the Martian surface.

The bacteria were living beneath a thin layer of ice coating a lava tube, a subterranean tunnel lava once flowed through, high in the Cascade Mountains. These frigid, dry conditions—an environment similar to Mars, albeit less extreme—are devoid of typical food sources, and the layer of ice blocks out much of the oxygen from the atmosphere. Rather than breaking down sugars and other nutrients, the bacteria have evolved to get by on what’s available: lots and lots of rock. They glean energy from a simple chemical reaction with the iron ...

Why Wool is Warm and Snowflakes Aren’t Always Pretty

Veronique Greenwood — Tue, 27 Dec 2011 17:16:40 +0000

If you live in the Northeast, chances are you’ve had a disappointingly balmy December so far (the snow seems to have taken a wrong turn somewhere and wound up over Texas instead). But when the air gets that snap and you reach for the wool socks, Emily Eggleston at Scientific American has a few factoids that promise to fascinate. Here’s why wool keeps you warm:

Wool keeps out the cold because it is an excellent insulator. Crimped and crisscrossed woolen fibers create tons of little air pockets. The tiny air masses within my socks have difficulty moving in and out of the fabric. Without convective heat transfer and contact with air of other temperatures, the spaces between wool fibers maintains a steady temperature.

And why are snowflakes sometimes beautifully crystalline and sometimes clumpy as cold oatmeal?

The two main snowflake shapes are plates and columns. Plates are the typical hexagonal flakes and columns are elongated, blocky crystals. As a cloud’s temperature moves below 32º F(0º C), it will pass through various phases of crystalline potential. If enough water is present in a cloud, between 32 and 23º F (0 and -5º C), plates will form, sending small ...

Why Do Mockingbirds Accept Invaders’ Eggs?

Veronique Greenwood — Thu, 22 Dec 2011 16:35:33 +0000

In the form of brood parasites, the bird world has enough irresponsible moms to start a reality TV show: cowbirds, for instance, lay their eggs in other species’ nests, stab most of the hosts’ eggs to death, and then leave their offspring to be raised by the host parents. The standing explanation for this involves most host birds being not that sharp on the uptake (watch a tiny warbler fussing over a cuckoo chick ten times its size (above) and you’d think that too). But maybe, a new study suggests, it’s sometimes to the host’s benefit to let imposter eggs stay in their nests.

The researchers chose mockingbirds as their hosts and cowbirds as their parasites, because mockingbirds usually fight like crazy to keep cowbirds of their nests but get strangely quiescent once the invaders have laid their eggs, a behavior that piqued the researchers’ interest. Once all the birds in the sample population had laid, the researchers went around adding and removing eggs from nests to see whether having a certain number of cowbird eggs affected mockingbird survival. They found that mockingbird eggs that shared their digs with cowbird eggs and suffered repeated cowbird invasions were more likely ...

Study: Hairs on a Spider’s Body Function as Individual Ears

Veronique Greenwood — Thu, 15 Dec 2011 17:33:04 +0000

Spiders are covered with fine hairs that can detect the faint movements of an enemy creeping closer, or a prey insect moving nearby. Scientists had long thought that these hairs functioned like the hairs humans have in our ears, which each tremble in response to a specific frequency and have to work together for us to hear sounds. But a new experiment suggests that each individual hair on a spider is capable of responding to a whole spectrum of sound, thus acting as an ear all on its own. As Dave Mosher writes at Wired:

The hairs responded best to sounds between about 40 Hz, a low rumble of bass, and 600 Hz, a car horn (humans ears can detect between 20 Hz and 20,000 Hz). That they picked up such a wide range of frequencies at all could overturn previous assumptions about how trichobothria [as the hairs are called] work.

“They operate like band-pass filters or microphones, not like the hairs in a human ear,” Bathellier said. In effect, each hair is its own ear that filters out background noise and zeroes in on biologically relevant information, such as an unwary cricket’s hopping or ...

Police Could Use DNA to Learn the Color of Suspects’ Eyes

Veronique Greenwood — Tue, 13 Dec 2011 21:37:38 +0000

In the dreams of crime scene investigators, no doubt, they can feed a piece of hair into a machine and see a reconstruction of what the owner looks like. There’s a hint of that fantasy in the news that Dutch scientists have developed a test intended help police tell from a crime scene DNA sample the color of a suspect’s eyes. This information is gleaned from examining six single nucleotide polymorphisms, small genetic markers that are used in DNA fingerprinting, and could potentially help steer investigations when there are few other leads on a suspect and there is no match in police DNA databases. But the test, which can tell whether someone has blue, brown, or indeterminate (which encompasses green, hazel, grey, etc.) eyes with an average of 94% accuracy, doesn’t seem to have been tested outside of Europe, which raises questions about how well it would work in populations with greater diversity. It’s also a little hard to feature how you could bring this information to bear in a vacuum of other details—you’d want to avoid hauling someone in just because they looked suspicious and have the same eye color as the readout ...

Further Evidence That Photosynthesis Involves Quantum Mechanics

Veronique Greenwood — Thu, 08 Dec 2011 17:20:20 +0000

Biologists have recently had cause to wonder whether the molecules they know and love are pulling some quantum trickery while they’re not looking: one of the large proteins that captures light in photosynthesis was observed in several studies apparently using coherence, one of the hallmarks of quantum mechanics, to determine the best possible route for shunting energy through its atoms. Now, further experiments that use lasers to tweak such proteins and observe their response have provided more evidence that this is happening—an exciting indication that the strange laws of quantum mechanics can affect the behaviors of large agglomerations of atoms.

Our own Sean Carroll of Cosmic Variance explained how coherence works when this phenomenon was observed in real plants at room temperature last year:

We can think about this in terms of Feynman’s way of talking about quantum mechanics: rather than a particle taking a unique path between two points, as in classical mechanics, a quantum particle takes every possible path, with simple paths getting a bit more weight than complicated ones. In the case of the [photosynthesis] protein, different paths for the energy might be more or less efficient at any ...

Israel Bans Cat Declawing. Punishment: One Year In Prison, $20K

Douglas Main — Wed, 07 Dec 2011 20:16:44 +0000

On November 28th Israel’s legislature unanimously passed a bill that outlaws the declawing of cats, except for certain medical reasons, making it a crime punishable by up to one year in prison and a fine of about $20,000 (or 75,000 shekels).

Declawing is a somewhat misleading term; in the procedure, called an onychectomy, the veterinarian typically removes all or most of the cat’s outer toe joint, bone and all. As declawing opponents have often pointed out, the human equivalent would be the amputation of your fingertips at or just above your third knuckle. Cats also use their toes/nails to walk upon; the Israel bill says the ban will help cats move around more normally, avoid certain medical complications, and defend themselves.

Declawing is not very common outside North America, and is banned in much of Europe, Australia, Turkey, Brazil, and elsewhere. It’s estimated that about 25 percent of American cats are declawed, typically done to protect the owner’s furniture. While the procedure is legal in most places in the U.S., it’s been banned in several cities in California, a state where it’s also illegal to declaw wild or ...

Worms Can Pass a Trait Down for 100 Generations…Without Using DNA

Veronique Greenwood — Wed, 07 Dec 2011 19:17:19 +0000

What’s the News: We’ve long had signs that when it comes to inheritance, DNA isn’t the be-all, end-all. Trees that have the exact same genes but were raised in different greenhouses behave differently. Worms with genes that impart long life can pass on that longevity to their progeny—even if they don’t pass on the genes. Both of these phenomena, we’ve discovered, come from epigenetic changes in tags attached to DNA that control whether genes get expressed.

But every now and then we get a whiff of other possible routes for inheritance, even stranger than that. A new paper in Cell reports that worms whose grandparents had the ability to fight viruses using a fleet of tiny RNA molecules retain these molecules even when they don’t have the genes for them. They can pass these molecules down for more than a hundred generations.

What They Saw:

This team engineered worms that didn’t have the genes to make the RNAs—which work by gumming up viruses’ replication machinery—and then bred them with worms that did for several generations. They ended up with some worms whose ancestors had had the virus-fighting molecules, but did not themselves possess ...

Ravens Appear to Communicate Using Gestures–A First for Non-Primates

Valerie Ross — Wed, 30 Nov 2011 18:42:30 +0000

Before they can talk, babies use gestures to communicate: sentiments such as “take this away,” “look over there,” and “put me down” can be made abundantly clear without words. Chimps gesture to each other, as well, pointing out particular spots where they’d like to be scratched or groomed. These symbolic gestures are believed to be an important precursor to language. Now, researchers have observed ravens using gestures in the wild—the only non-primates seen doing so.

Over two years, the researchers saw ravens pick up stones, moss, and other non-edible items with their beaks, and display or offer those objects to another bird, usually of the opposite sex. The other raven, in turn, usually looked over in response, and often had positive interactions with the gesturing raven. Other birds gift gifts while courting, but in this case, the birds weren’t delivering the moss and stones to the recipient; the objects aren’t put towards a purpose like making nests, as such gifts often are, and seem to be used solely to get noticed and spark an interaction. Since ravens form monogamous, highly cooperative pairs, these interactions could be used to attract ...

Atmospheric Remnants of Nuclear Tests Reveal Antarctica’s Tiny “Old-Growth Forests”

Douglas Main — Wed, 30 Nov 2011 13:47:33 +0000

Hardy Antarctic moss.

Ah, Antarctica. A vast expanse of ice, interrupted by mountains, ice… and more ice (with the occasional penguin). But in the East of the continent and on the Windmill Islands near Australia’s Casey research station, bare ground can actually be seen during summer months. Here Antarctica’s endemic plants dwell: lichens, terrestrial algae, and mosses. These smatterings of bryophytes are amongst the hardiest flora in the world, providing a home for a variety of minute life. They survive being covered in snow most of the year, only growing briefly during the summer months, watered by snowmelt. Except for in-person observations made over the last two decades, little definitive was known about these oases of diversity, like their age or how they might respond to changes in climate.

But now, some of the moss’s secrets are out. A recent study in the journal Global Change Biology found that some of these plants must be more than a century old, and a few may even be thousands of years old, said researcher and study author Sharon Robinson via email. On average these mosses grow at the glacial speed of 1 millimeter per year—and some of the turfs are meters thick. That ...

Did Parasites Drive Human Evolution?

Veronique Greenwood — Wed, 16 Nov 2011 17:37:00 +0000

Hookworms are longer-lived than viruses and bacteria;
they could have had a more significant effect on human evolution.

Humans live in all sorts of places—high deserts, tropical lowlands, frigid tundra. Over the millennia, you’d expect each population’s assortment of genes to evolve to reflect the demands and dangers of its home environment: those who live in the deserts would possess genes for extra skin pigments to help keep their tender integument from burning (like African peoples), and those who live in sub-zero climes much of the year would have genes that keep them well-insulated in fat (like the Inuit). But what if factors other than climate, like the food available nearby or the viruses, bacteria, and parasites native to the area, also had an effect on various human populations’ genetic toolkits?

It’s a fascinating question, but, given that we have to reconstruct all this supposed evolution from the current state of modern genomes, finding an answer isn’t easy. A recent paper takes an important first step by looking for correlations between 500,000 different genetic markers and certain environmental characteristics, like humidity, temperature, the local diet, and the prevalence of parasites and other pathogens.

The researchers started out ...

What Stands Between You and the World’s Most Expensive Burger

Veronique Greenwood — Tue, 15 Nov 2011 20:05:24 +0000

You can dream, but…lab-grown processed meats, let alone steak, are a very
long way off still.

Part of what stands between you and a lab-grown meat patty (a perennial source of fascination around here) is your gag reflex: the pale strips of cultured muscle cells that are currently the top contender for Petri-dish burgerdom look like scraps of mold, and they must be “exercised”—stretched between Velcro tabs—to strengthen and gain meat-ish texture. A patty made from them will be a hand-assembled stack of about 3,000 scraps, and in order to give the stuff color and iron, the lead scientist of the project opined to Reuters, they might need to soak it in lab-grown blood. Gah.

Still, factory farming ain’t pretty either, and the sheer amount of land and other resources we dedicate to meat production can be enough to make you gag as well.

This particular cultured meat project—there are many—hopes to have its first proof-of-concept burger made by August or September next year. But there is a long way to go before this stuff has even a chance of hitting the mainstream, especially since, on top of the ...

CA Birds Are Getting Bigger; PA Birds Are Getting Smaller

Douglas Main — Wed, 09 Nov 2011 13:01:01 +0000

California birds are getting slightly bigger, according to a study published in Global Change Biology in which researchers measured and weighed 33,000 birds over the past 40 years. The increases were small, but significant: in the last 25 years robins have grown 0.2 ounces in mass and 1/8th of an inch in wing length, for example. But the finding runs counter to the only other long-term study measuring avian size in North America, which found that birds in Pennsylvania have shrunk slightly over recent decades. And it seems to disagree with other recent suggestions that animals may shrink in a warming world: Bergmann’s rule holds that animals generally get bigger as they get farther away from the equator, because larger animals are better able to retain heat.

So what’s going on? The researchers have a number of hypotheses, all related to climate change. More severe weather on the West Coast, for example, could perhaps favor bulked-up birds that can store more energy to survive storms. Or maybe warmer temperatures cause changes in rainfall patterns that ultimately lead to more food for birds (a pattern that may be different elsewhere, like ...

One Species, Ten Patterns? Why Poison Dart Frogs Dress Differently

Veronique Greenwood — Tue, 08 Nov 2011 17:22:25 +0000

Above, the real deal; below, the clay models used to test predators’ reactions to local and foreign frog markings.

Sometimes, you have to make a thousand frogs from modelling clay to make your point.

A single species of poison dart frog sports ten completely different coloration patterns, depending on where they live. Are these color divisions being encouraged by the birds that prey on them?, wondered evolutionary biologist Mathieu Chouteau from the University of Montreal. To find out, he set out 1800 clay frogs, made by himself and his (saintly!) girlfriend, in the Peruvian forest.

Since each coloration pattern lives in a different area, in each spot he put out a frog with the local pattern, a frog with a foreign pattern, and a frog with no pattern at all, and looked at how predatory birds reacted to them. He found that indeed, birds knew that their local pattern meant a poisonous meal, and they were more likely to avoid those frogs while preying heavily on the foreigners. The birds’ apparent knowledge of their local pattern could indeed be keeping the different populations of frogs from mixing.

But why do the frogs, which are all of one species, ...

As Permafrost Melts, Methane-Munching Soil Bacteria Come to Life

Veronique Greenwood — Mon, 07 Nov 2011 20:39:21 +0000

There’s a lot going on in Arctic permafrost as it melts and soil bacteria become more active. A new study explores how these bacteria may help or hinder our efforts to control the greenhouse gasses in the atmosphere.

What’s the News: Melting permafrost in a warming world could mean lots of greenhouses gasses, especially methane, released into the atmosphere. But it also means an unusual community of soil bacteria coming out of hibernation, so to speak. A new study looks at what those permafrost microbes do, exactly, as their environment warms up.

How the Heck:

The researchers took cores of frozen soil from Alaska and started melting them in the laboratory. As the permafrost melted, they used a technique called metagenome sequencing, harvesting and sequencing DNA from the samples, to identify the permafrost denizens and to see what kinds of proteins they were manufacturing. By performing this step while the samples were frozen and at two points during the melting process, they were able to see how the bacterial makeup of the soil changed over the course of the melt, as some bacteria reproduced like crazy and others did not. They also monitored the amount of ...

Vampire-like Predatory Bacteria Could Become A Living Antibiotic

Douglas Main — Wed, 02 Nov 2011 18:07:59 +0000

The bacterium Micavibrio aeruginosavorus (yellow), leeching
on a Pseudomonas aeruginosa bacterium (purple).

What’s the news: If bacteria had blood, the predatory microbe Micavibrio aeruginosavorus would essentially be a vampire: it subsists by hunting down other bugs, attaching to them, and sucking their life out. For the first time, researchers have sequenced the genome of this strange microorganism, which was first identified decades ago in sewage water. The sequence will help better understand the unique bacterium, which has potential to be used as a “living antibiotic” due to its ability to attack drug-resistant biofilms and its apparent fondness for dining on pathogens.

Anatomy of a Vampire:

The bacterium has an interesting multi-stage life history. During its migratory phase it sprouts a single flagellum and goes hunting for prey. Once it find a delectable morsel of bacterium, it attacks and irreversibly attaches to the surface, and sucks out all of the good stuff: carbohydrates, amino acids, proteins, DNA, etc. Sated, the cell divides in two via binary fission, and the now-depleted host is left for dead.

Hungry for Pathogens:

M. aeruginosavorus cannot be grown by itself; it must be cultured along with another bacteria to feed upon. A 2006 study found that it ...

A Tiny Mutation Makes Fish Immune to PCB Poisoning

Veronique Greenwood — Mon, 31 Oct 2011 16:07:13 +0000

Because of two missing amino acids, this tomcod can swim through PCBs—and survive.

PCBs are nasty pollutants—they mess with hormones and have been linked to cancer—but until they were banned in 1977, dumping them in US rivers was a common practice for companies like GE. While plenty of wildlife suffered from ingesting PCBs, some fish in the Hudson and other be-sludged rivers evolved an immunity to the poisons, a intriguing example of quick adaptation that scientists have been watching with interest. A recent Economist article focusing on this research describes the fascinating genetic ju-jitsu that allows fish in the Hudson and in the harbor at New Bedford, MA, to keep themselves alive in PCB-contaminated waters.

PCBs do their damage by binding to a protein called the aryl hydrocarbon receptor, or AHR, thus stopping it working properly. AHR is a transcription factor, meaning that it controls the process by which messenger molecules are copied from genes. These messenger molecules go on to act as the blueprints for protein production, so preventing a transcription factor from working can cause all sorts of problems. Both Hudson tomcod and New Bedford killifish, however, have unusual AHR molecules. ...

Toxic Pufferfish Invade Eastern Mediterranean, Killing People and Irking Fisherman

Douglas Main — Mon, 31 Oct 2011 14:08:33 +0000

In the Eastern Mediterranean, the pufferfish has arrived. And nobody’s too happy about it. The fish, also known as the silverstripe blaasop or Lagocephalus sceleratus, was first confirmed in Turkey in 2003 and has been spreading throughout the area. The problem with this unassuming fellow is that it contains tetrodotoxin, a neurotoxin that can be deadly to humans and for which there is no known antidote. Consumption of the fish has killed at least 7 people in Lebanon in the past few years, according to The Daily Star, and likely affected many more. A 2008 study found that 13 Israeli patients who ate the blaasop had to receive emergency medical attention at the hospital, where they didn’t recover for four days.

Besides being poisonous the pufferfish is also strong and has a sharp beak that allows it to cut through fishermen’s nets. The fish is native to the Pacific and Indian Ocean, and lives in the Red Sea, from which it likely migrated through the Suez Canal. As of 2005, there were as many as 745 exotic species in the Mediterranean, many of which likely arrived via the ...

Wolves May Not Need to be Smart to Hunt in Packs

Veronique Greenwood — Wed, 26 Oct 2011 19:31:27 +0000

Wolves have been observed working together to ambush a prey animal, leading researchers to consider whether they are displaying foresight, planning, and other signs of impressive smarts. But new work suggests that as long as each wolf obeys a couple simple rules, the seemingly complex behavior emerges naturally, without any need for higher intelligence.

Using a computer model, researchers had each virtual “wolf” follow two rules: (1) move towards the prey until a certain distance is reached, and (2) when other wolves are close to the prey, move away from them. These rules cause the pack members to behave in a way that resembles real wolves, circling up around the animal, and when the prey tries to make a break for it, one wolf sometimes circles around and sets up an ambush, no communication required.

Just because certain aspects of pack hunting could be emergent—arising from the interplay of certain basic rules—rather than the fruits of intelligence doesn’t mean that they necessarily are, nor does it mean that wolves are dumb. But it does suggest that pack hunting isn’t necessarily the reason that wolves form packs, which opens up space for evolutionary biologists to jump and ...

Largest Single-Celled Organism Found 6 Miles Beneath Sea

Douglas Main — Mon, 24 Oct 2011 20:06:18 +0000

Researchers have found new examples of the strange singled-celled creatures called xenophyophores more than six miles beneath the surface of the Pacific in the Mariana Trench. At more than four inches in length, they are perhaps the largest single-celled organism on Earth. These protists make a living by sifting through sediments and can accumulate high levels of toxic metals like uranium, lead, and mercury.

Watch the World Burn: Cool NASA Video Shows Fires Around Globe

Douglas Main — Fri, 21 Oct 2011 16:43:14 +0000

Some men just want to watch the world burn. Count me as one of them, at least when it comes to this video from NASA showing fires taking place the world over. Seventy percent of the world’s blazes take place in Africa—apparently making it the “fire continent,” according to the narrator. Perhaps surprisingly, especially given recent wildfires in the American West and Southwest, only 2 percent of the globes conflagrations take place in North America. NASA used two satellites, Terra and Aqua, to visualize patterns of vegetation, snow/ice cover, and fires worldwide from July 2002 to July 2011.

[Via NASA]

Parasite Turns Wasps into Wandering, Would-Be Royalty

Valerie Ross — Fri, 21 Oct 2011 13:00:40 +0000

Parasitic wasps have a terrifying but weirdly impressive knack for taking over the bodies and brains of other many-legged creatures, making spiders weave them bespoke silk cocoons, obedient cockroaches incubate their eggs, and paralyzed, partially devoured ladybugs guard their young. But for the European paper wasp, as a new study describes, the tables are turned: It’s the host rather than the parasite—and the things the Xenos vesparum fly larvae inside it lead it to do are at least as odd as any of the above.

Brandon Keim at Wired describes the saga in all its bizarre detail. Particularly striking is the fact that the larvae make the wasps they live in disregard their spot in the strict wasp social order. While the infected wasps start out as workers, they spend all winter chowing down and hanging out with the queens of other colonies:

“The parasite is triggering a queen behavior, but you can’t say they’re really queenlike, because they’re not reproductive,” said [entomologist Fabio] Manfredini. Come spring, the real queens go off to prepare nests, but infected wasps stay behind, waiting. Inside them, gestation is nearly complete.

Then, with exquisite ...

Worms with Genes for Long Life Pass on Longevity to Offspring…Even Without the Genes

Veronique Greenwood — Fri, 21 Oct 2011 12:40:27 +0000

Nematode worms live longer if their grandparents had particular genes.
But they don’t need to receive the genes themselves to feel the effects.

What’s the News: Scientists have discovered that worms who’ve been given mutated genes that let them live longer pass on their longevity to their descendants—even when the descendants don’t receive the genes. How does it work?

How the Heck:

The team had previously found that disabling a set of three proteins, called the H3K4me3 complex, would cause worms to live longer—usually for about 27 days rather than 20 days, an increase of 35%. This complex manages the packing of DNA, which is important in the expression of genes. (If DNA is loosely packed, it’s easy for the cell’s machinery to read it and make the proteins the genetic code specifies. But if DNA is tightly packed, it won’t be read out.) When the complex is disabled, some genes are trapped in the tightly packed state. The team thinks that genes related to aging are among those taken out of commission. When worms carrying a malfunctioning complex bred with normal worms, their descendants had the normal, functioning DNA-packing proteins, yet somehow lived as long as their long-lived ...

California Bans Trade in Shark Fins

Douglas Main — Tue, 11 Oct 2011 23:37:05 +0000

Fresh shark fins drying on sidewalk in Hong Kong. Credit: cloneofsnake / flickr

On Friday, California governor Jerry Brown signed into law a bill outlawing the trade in shark fins, making it illegal for them to be imported, possessed, or distributed in the state. Chinese chefs were angered by the decision, since the fins are the prime ingredient in shark fin soup, a prized and expensive delicacy (although most Chinese voters in California support the ban… and so does retired NBA player Yao Ming). Other parts of shark meat are not highly valued, though, so most sharks caught are “finned” and thrown back into the ocean, where they slowly bleed to death. As many as 73 million sharks are killed each year, most for this purpose, and shark populations around the world are in serious decline—perhaps 30 percent of shark species are endangered.

The importation of shark fins to the U.S. is against the law, but illegal importation continues and consumption remains popular amongst Chinese immigrates and other groups. The soup is available in at least 23 states, for example, and In New York City alone there ...

FDA Completes Review of First Genetically Modified Animal for Consumption

Veronique Greenwood — Tue, 11 Oct 2011 20:12:25 +0000

The AquAdvantage salmon.

When most people say “genetically modified organism,” they usually mean a plant—corn, perhaps, or an eggplant. But that may soon change. The FDA has completed its analysis of the first genetically modified animal likely to hit supermarket shelves: the AquAdvantage salmon, made by Massachusetts-based AquaBounty Technologies, Inc. Thanks to some added genes, the salmon grows 2-6 times the size of a normal Atlantic salmon in half the time, promising some respite for the planet’s heavily taxed natural fish stocks, a third of which are near extinction or exhaustion. Talking Points Memo’s IdeaLab reports that a source close to the review process says that the FDA’s environmental impact statement, which looks at what effect the salmon will have on the environment and seems to be favorable, has been passed on to the White House’s Office of Management and Budget.

As always with genetically modified organisms, there are questions about how the salmon’s manufacturers plan to keep its genes from getting loose in the environment. AquaBounty has developed a way to make the fish sterile, which would make spreading their genes quite tricky. At the moment, however, it only works on 98% of the ...

Study: Fish Have Been Jumping on Land for 150 Million Years and Hiding it From the Fossil Record

Douglas Main — Tue, 11 Oct 2011 18:01:27 +0000

Mosquitofish can leap with “skill and purpose.”

How did animals move from water to land? The answer may have just got a little murkier. A study published this month in the Journal of Experimental Zoology found that two distantly related fish share a similar method for jumping about on land, suggesting that a common ancestor evolved this ability long ago. But unlike amphibious fish such as the mudskipper, which has pectoral fins adapted to “walking” on land, these fish have no specialized equipment for leaping, and would therefore leave no evidence of their talent behind in the fossil record.

In the lab scientists placed fish on a moist surface and filmed their leaps using a high-speed camera (see video below). In this study researchers compared the western mosquitofish, which is known to hop onto land when pursued by predators, and the zebrafish, which doesn’t leave the water in its natural habitat. And yet in the lab both fish can jump with “skill and purpose,” and in very similar way. This led researchers to hypothesize that a common ancestor of the two fish evolved the capacity to jump on land, more than ...

Do Neutering and Spaying Cause Depression in Pets? No Word Yet, But an Interesting Question

Veronique Greenwood — Mon, 10 Oct 2011 17:17:08 +0000

Hormones are major mood-regulators, as anyone who has been cranky before a period or had their reproductive organs removed for medical reasons can tell you. In fact, depression is a common side effect of such surgeries in humans. But does that extend to some of the most regularly de-hormoned animals out there—our pets? That’s the thought-provoking thesis of a recent Slate piece, and while there’s been no systematic research on how such surgeries affect cats and dogs, a smattering of research has suggested that having your supply of hormones eliminated does affect the mood of mice and primates, free of the confounding influences one finds in humans. Madeleine Johnson of Slate describes one set of experiments:

[Researchers in Japan] reasoned these snow monkeys could model mood changes due to ovariectomy without confounding variables like the social stigma of barrenness that might affect women. The center picked 10 females of equivalent rank in the dominance hierarchies and removed the ovaries and uterus from five of them. The other five had their “tubes tied,” so were sterile but still had intact ovaries. Since the monkeys wouldn’t understand the biological ramifications of surgery, and would have similar social lives, ...

Diving Expedition Finds New Life in the Dead Sea

Valerie Ross — Sat, 01 Oct 2011 12:00:19 +0000

Israeli and German scientists recently took the plunge into the murky, salty Dead Sea, making what they say is the first scientific diving expedition there. Scouring the seafloor, they saw small freshwater springs—with mats of salt-loving, never-before-seen microorganisms coating the surface of nearby craters. In these waters—too salty for large animals, too rich in magnesium for many bacteria—seeing so much life was a surprise.

While floating in the Dead Sea is a popular tourist pastime, scuba-ing into its depths is a difficult and dangerous endeavor. Since the salty water is so buoyant, the divers had to carry 90 pounds each to weigh them down. Swallowing some of the salty water—a not-implausible occurrence during a dive—would make the larynx swell up, leading the diver to suffocate. If that weren’t enough, getting the water in your eyes would be painful at best, and potentially blinding. The scientists wore full face masks during their dive, and apparently weren’t scared off; they’re headed back down for a follow-up study in October.

Junk DNA Gave Us the Modern Uterus, in a Giant Genetic Cut-and-Paste Operation

Veronique Greenwood — Tue, 27 Sep 2011 12:00:31 +0000

What’s the News: A new analysis finds that many of the genes behind the development of modern mammalian pregnancy are controlled by mysterious genetic elements called transposons, long referred to as “junk DNA.” The results suggest that the placental uterus did not evolve gradually but instead arose from a massive, transposon-driven genetic rewiring.

How the Heck:

The research team looked at the DNA of uterine cells from the possum, a marsupial that gives birth two weeks after conception and shelters its developing young in a pouch, and compared them with cells from armadillos and humans, which both carry their children to term in a womb lined with a nutrient-rich placenta. The uterine cells of armadillos and humans shared more than 1,500 active genes that possums lacked. Looking closer, the team saw that a number of these genes—about 13%—were very near on the genome to a particular kind of transposon specific to placental mammals. The origins of transposons, jumping genetic elements that copy and insert themselves in their host genomes seemingly at random, are still unclear, and their purpose has long been so opaque that they were called “junk DNA” until relatively recently. We now know that they play an important ...