Hyperion

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The latest view of Hyperion by Cassini. Image Credit: NASA/JPL-Caltech/Space Science Institute

The latest view of Hyperion by Cassini.  Image Credit: NASA/JPL-Caltech/Space Science Institute

NASA titled this image quite appropriately “Spongy Hyperion”.  This visible light image taken through a blue filter really does make the little moon look like a sponge.

Hyperion is a little moon being only 168 miles (270 km) across and it isn’t very uniform in shape either as you can tell.  Another interesting thing is the moon doesn’t spin so much as it tumbles its way around Saturn.  Tumble is a better descriptor because it has a variable “spin or tumble” rate and orientation.

Mercury Not Like Other Planets

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Click here to view the embedded video.

From the Carnegie Science Center:

The MESSENGER spacecraft has shown scientists that Mercury doesn’t conform to theory. Its surface material composition differs from both those of the other terrestrial planets and expectations prior to the MESSENGER mission, calling into question current theories for Mercury’s formation. Its magnetic field is unlike any other in the Solar System, and there are huge expanses of volcanic plains surrounding the north polar region of the planet and cover more than 6% of Mercury’s surface

Source

NCBI ROFL: Salivary testosterone levels in men at a U.S. sex club. | Discoblog

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“Vertebrate males commonly experience elevations in testosterone levels in response to sexual stimuli, such as presentation of a novel mating partner. Some previous human studies have shown that watching erotic movies increases testosterone levels in males although studies measuring testosterone changes during actual sexual intercourse or masturbation have yielded mixed results. Small sample sizes, “unnatural” lab-based settings, and invasive techniques may help account for mixed human findings. Here, we investigated salivary testosterone levels in men watching (n = 26) versus participating (n = 18) in sexual activity at a large U.S. sex club. The present study entailed minimally invasive sample collection (measuring testosterone in saliva), a naturalistic setting, and a larger number of subjects than previous work to test three hypotheses related to men’s testosterone responses to sexual stimuli. Subjects averaged 40 years of age and participated between 11:00 pm and 2:10 am. Consistent with expectations, results revealed that testosterone levels increased 36% among men during a visit to the sex club, with the magnitude of testosterone change significantly greater among participants (72%) compared with observers (11%). Contrary to expectation, men’s testosterone changes were unrelated to their age. These findings were generally consistent with vertebrate studies indicating elevated male testosterone in response to sexual stimuli, but also point out the importance of study context since participation in sexual behavior had a stronger effect on testosterone increases in this study but unlike some previous human lab-based studies.”

Photo: Flickr/ F3LONY
Thanks to @cqchoi for today’s ROFL!

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Discoblog: NCBI ROFL: Women’s bust size and men’s courtship solicitation.
Discoblog: NCBI ROFL: Beauty week: Blond, busty, skinny waitresses get bigger tips.

WTF is NCBI ROFL? Read our FAQ!


Low-Tech Vikings May Have Used Mineral With Funky Optics to Reach New World | 80beats

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What’s the news: Viking legend has it that sailors could hold up crystal sunstones to the sky to help them find their way. Turns out the legend could be true. In a study published this week in the journal Proceedings of the Royal Society B, a team of researchers found that a type of crystal called an Icelandic spar commonly found in that country could accurately reveal the position of the sun in cloudy or near-dark conditions.

How Vikings Got Around:

  • Researchers have long wondered and argued about how the Vikings were able to successfully navigate their way around the Northern Hemisphere in the late eighth to 11th centuries, hundreds of years before the magnetic compass reached Europe around 1300. Besides the direction of the wind, waves, and swell, the only way to navigate during the day away from shore is by knowing the sun’s direction. But that’s not so easy on a foggy or stormy day, or during the long twilight of Northern summers.
  • Historians have speculated that, due to their optical properties, crystals of calcite (a common form of calcium carbonate) could have been used to tell direction, but until now the theory hadn’t been tested.

The Magic of Calcite:

  • Icelandic spars are crystals of calcium carbonate which have a special property called birefringence: light hitting the mineral is split and follows two parallel paths through it, which explains how calcite makes objects look doubled. The relative brightness of the two images—the amount of light following the two different paths—depends on the light’s orientation to the crystal. The researchers showed that this can be used to locate a hard-to-find light source, like the sun on a cloudy day.
  • The basic idea is that at a certain orientation to a light source, the crystal produces two light beams of equal brightness, a contrast the eye can measure surprisingly well. If you figure out what orientation of the crystal produces this effect when the sun is visible, you can repeat the procedure in the fog to find the sun.
  • Testing the method with various Icelandic spars, the researchers were able to establish the direction of the sun to within 5 degrees.

Is This the Vikings’ Secret?

  • So far no crystals have been found in known Viking settlements or artifacts. But one such crystal was recently found in the 1592 shipwreck of an Elizabethan vessel in the English channel. The researchers think its likely to have been used to aid navigation, due to its shape and their calculation that the presence of even the one large cannon found aboard would interfere with compass readings. This suggests these types of sunstones were in use more than 200 years before polarized light was first discovered, and possibly used even earlier by the Vikings to navigate the open seas.

Reference: Guy Ropars, Gabriel Gorre, Albert Le Floch, Jay Enoch, and Vasudevan Lakshminarayanan. A depolarizer as a possible precise sunstone for Viking navigation by polarized skylight. Proceedings of the Royal Society A. Published online 2 November 2011. DOI: 10.1098/rspa.2011.0369

Image credit: WikiMedia Commons 


Column: Looking for New Forces | Cosmic Variance

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While my first column for Discover was on the multiverse, the second one is more down to Earth (as these things go): searching for new forces. Of course we are searching for new short-range forces at the Large Hadron Collider and in other particle-physics experiments, but here I’m talking about long-range “fifth forces.” While there are plausible motivations for searching for such forces, and the experimentalists have done an heroic job in constraining them, I argue that the most impressive thing is how we can say what forces are not out there — in particular, anything that would have any important effect on everyday life. There probably are more forces than we know about, but they’re only going to be of direct interest to physicists, I’m afraid. No tractor beams.


NASA spies the birth throes of a new iceberg | Bad Astronomy

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The Pine Island Glacier is a massive flowing river of ice on the western Antarctic ice shelf. And by massive, I mean massive: it’s 250 km (150+ miles) long, and has an area of 175,000 square kilometers — that’s bigger than the state of Iowa! Every year, a staggering 79 cubic kilometers (19 cubic miles) of ice drains from this glacier in the ocean, flowing via a tongue of ice floating in the water off the main land.

Flying over the glacier on October 14, scientists aboard a NASA DC-8 airplane as part of the IceBridge mission were startled to see a huge crack across the glacier. Flying back over it on October 26, they were able to photograph and measure this huge rift, and found it will almost certainly soon give birth to a huge iceberg. Check out this lovely picture of the ice crack:

[Click to enfloenate - and you really want to; it's amazingly beautiful.]

Brrrr. The scale of this crack is much larger than you might think: it’s 80 meters wide on average, and about 150 meters wide in the photo above, the size of a football stadium! It runs for 29 km (18 miles), and it’s pretty deep; a topographic map (shown here) indicated it’s 50-60 meters in depth.

Remember, Antarctica is a continent, a land mass, but this part of the glacier is flowing out over the ocean, and is floating. The ice at this point in the glacier is about 500 meters thick — more than a quarter mile! — but cracks like these grow with time. Eventually, it’ll snap, and the seaward part of the ice will float free, a newly-born iceberg that will be something like 800 square kilometers (300+ square miles) in area. Such cracks have been seen before, but never mapped in such detail using airborne observations.

NASA put together a video about the flight over Pine Island:

This is wonderful science, studying how our dynamic planet changes over time. And to get to see such an amazing event as it’s just getting started is very exciting! You can see other pictures from this flight on the NASA Ice Flickr page, and I suggest you do: the images are really cool (har har) and the science they’re doing is important — as the Earth warms (and it is) our ice is disappearing. Missions like IceBridge will help us understand how that is happening and what the effects are.

Credit: Digital Mapping System team and Michael Studinger; NASA/Goddard Space Flight Center/Scientific Visualization Studio

Related posts:

- Enormous glacier calves in largest Arctic event seen in 48 years
- Ice island heading south off Labrador
- Titanic’s revenge
- Our ice is disappearing


Bob Rood | Bad Astronomy

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Chances are, you didn’t know Bob Rood, and that’s too bad. A professor of astronomy at the University of Virginia, he was one of the good guys. He taught stellar interiors, a class I still look back at fondly. I learned a lot about astrophysics that semester, though I do recall an oral exam where I did, um, less than well… yet Bob was generous, supportive, and helpful to an extremely nervous grad student who was on the verge of throwing up during the exam.

Bob died yesterday. I dithered on what to write; it’s so hard to say the right thing. But then Nicole Gugliucci wrote a wonderful post about Bob, and there’s not much I can add to it. When I found out last night he had died, I told my wife about one of my favorite memories of Bob — it involves a coffee mug he had, one that I told Nicole specifically to look for when she talked to Bob a few years ago. I was glad to see Nicole wrote about that too; I think it sums him up pretty well.

One of the very few really positive things we can do that has a lasting effect is to shape the minds of those around us, teach them about the Universe, and instill a love for knowledge. Bob did all that. We could use a lot more like him.


NCBI ROFL: The physics of penguin huddling. | Discoblog

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Coordinated movements prevent jamming in an Emperor penguin huddle.

“For Emperor penguins (Aptenodytes forsteri), huddling is the key to survival during the Antarctic winter. Penguins in a huddle are packed so tightly that individual movements become impossible, reminiscent of a jamming transition in compacted colloids. It is crucial, however, that the huddle structure is continuously reorganized to give each penguin a chance to spend sufficient time inside the huddle, compared with time spent on the periphery. Here we show that Emperor penguins move collectively in a highly coordinated manner to ensure mobility while at the same time keeping the huddle packed. Every 30-60 seconds, all penguins make small steps that travel as a wave through the entire huddle. Over time, these small movements lead to large-scale reorganization of the huddle. Our data show that the dynamics of penguin huddling is governed by intermittency and approach to kinetic arrest in striking analogy with inert non-equilibrium systems, including soft glasses and colloids.”

Bonus quote from the Discussion in the full text:

“In addition, huddle movements allow separate smaller huddles to merge into larger clusters. Such merging is analogous to the merging of magnetic domains as the thermodynamic temperature is decreased towards the Curie point, the temperature above which a magnet loses its magnetism, or analogous to a phase transition in a disordered material that is brought towards a critical point. This is an essential process in condensed matter physics, penguins included.”

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Discoblog: NCBI ROFL: How hard can I snuggle my penguin without waking him?
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Discoblog: NCBI ROFL: The sea lion solution to sexual harrassment: keep fewer males around.

WTF is NCBI ROFL? Read our FAQ!


Stunning wren duets are conceived as a whole but sung in two parts | Not Exactly Rocket Science

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In the mountainous forests of Ecuador, you might hear this fast, lilting song:

The melody sounds like it comes from a single bird, but it is actually sung by two: one male and one female. The couple alternates their syllables with almost unbelievable precision, each one placing its notes in the gaps left by its partner. The result is one of nature’s finest duets. And the singers are a pair of (rather drably named) plain-tailed wrens.

By studying the singing wrens, Eric Fortune from Johns Hopkins University has found that each bird has brain circuits that encode the entire song. Rather than focusing on just their own contribution, they process the whole melody. Their duet is conceived as a whole in both their brains, but emerges as two distinct parts, one from each beak.

Fortune studied the singing birds in the wild. “Before we done the study, we’d never seen the birds and we didn’t know where they lived,” he says. With the help of Ecuadorian naturalists, he found the birds on the side of Antisana volcano, living in thick bamboo thickets that he had to hack through with machetes. “When the birds are nearby, their song is actually painful to hear because it’s extremely loud,” says Fortune. “On the computer, you don’t get a sense of the power it has. It rings in your ear, and because it’s coming from two different locations, it’s very hard to localise.”

Across 15 months, Fortune recorded over 150 hours of wren songs. He noticed that both males and females also sing on their own. Their produce exactly the same notes that they would do in the duet, leaving odd gaps in the places where their partners would fill.

This suggested that the duetting wrens might just be singing their individual parts, relying on faultless timing to stitch the two songs together into one. That’s less of a partnership, and more two birds shouting simultaneously and somehow failing to sing over each other. This idea is consistent with studies in other songbirds but it can’t be the real story for the wrens.

Fortune found that when the birds sing alone, they leave longer gaps than they would do when singing together. This suggests that they tailor the timing of their notes to what their partners are doing, using each syllable as a cue to produce the next one. That became obvious when the males screw up (and they often do). In several of Fortune’s recordings, the males often fumbled their notes in the middle of long sequences. When this happened, the females carried on and left longer gaps than usual between their syllables. It seems the female takes the lead in the duet, setting the rhythm that the male then follows.

The field recordings were intriguing, but Fortune wanted to understand what was happening the birds’ brains when they sang together. To find out, he captured six wrens and played them a variety of tunes, both solos and duets. While they listened, Fortune recorded the activity in their HVC – a part of the songbird brain responsible for learning and producing songs.

The majority of the wrens’ HVC neurons responded more strongly to the full duet than to the individual songs put together. And in both birds, the female syllables trigger stronger responses in the HVC than the male ones. That flies in the face of previous studies: it’s surprising enough that the birds’ HVCs are responding to the songs of other birds at all, let alone more strongly than to their own notes.

Both wrens have clearly encoded the whole duet in their heads, and that both are aware that the female takes the lead. They seem almost wired for cooperation – their brains buzz more strongly when they’re singing together than apart.

Fortune thinks that the same thing could apply to other species. He writes, “Consider, for example, two people cooperating to dance a tango. Certainly each person knows his or her own part of the dance and possibly the partner’s contribution, but these data suggest that premotor circuits in both individuals preferentially encode the combined cooperative behavior.”

Reference: Fortune, Rodriguz, Li, Ball & Coleman. 2011. Neural Mechanisms for the Coordination of Duet Singing in Wrens. http://dx.doi.org/10.1126/science.1209867

Photo by Eric Fortune and Melissa Coleman ; graphic by Zina Deretsky

More on birdsong:

Video of the Progress re-entry! | Bad Astronomy

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Last week I posted a picture of the fiery re-entry of a Progress re-supply ship as seen by Mike Fossum on board the space station. It was one of several pictures he took, and via Universe Today is a video of the descent of the spacecraft!

Holy wow! You can see the trail of plasma starting to blow off the main spacecraft just as the video begins, and if you look carefully you can see bigger chunks of material falling off the main body — just like in the big picture I posted earlier (seen below).

While this may seem like a waste of a spacecraft, in fact this serves a very useful purpose: it gets rid of trash and other cast-offs by the astronauts on the International Space Station. By collecting it and getting rid of it all at once they don’t have to worry about creating more space debris which is a hazard to other satellites, or even the ISS itself — a very real concern.

Moreover, Progresses are not re-usable, so there’s no sense in trying to land them again. Also, it takes less fuel to slow a Progress spacecraft enough to let it burn up in our atmosphere than it would to slow it down enough to land it safely anyway. That means even more savings in getting payloads to space.

So all in all it makes sense to simply use them as a way to keep the ISS tidy. It may be a bit ignominious, but wow, what a way to go!

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- The fiery descent of Atlantis… seen from space!


October’s solar blast, seen from the side | Bad Astronomy

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Speaking of solar storms causing gorgeous auroral displays…

In late October, a coronal mass ejection (CME) — a violent explosion of subatomic particles erupting from the Sun at high speeds — blasted away from our star, impacting the Earth, and setting off aurorae seen as far south as Arkansas. It was cloudy here in Boulder, but from space, the view is always clear. NASA’s STEREO spacecraft are twin machines, one ahead of the Earth, one behind, both staring at the Sun 24/7. They are currently roughly 100° around the Earth’s orbit, so they are essentially seeing the Sun "from the side".

STEREO A, ahead of the Earth in its orbit, captured images of the Sun during October’s solar hissy fit, and got dramatic footage of the explosion:

Yegads. [Make sure you click the HD button to see this in all its glory.]

The Earth is off to the left, well off-screen, in this animation. The Sun is blocked by a circular mask, so fainter things can be seen (its disk is represented by the white circle). The big CME occurred early on October 22 and is followed by others.

The energy and raw power of this event is staggering: a billion tons of matter was hurled away from the Sun at several million kilometers per hour. This completely dwarfs into nothing all of humankind’s energy output, and is vastly greater than the explosive yield of all nuclear weapons at the height of the Cold War combined.

And during its active phase, the Sun tosses these things off like a gourmand barely stifles a belch.

The danger to Earth from CMEs is real, if rare. A powerful one can generate strong electric currents in conductors (like power lines) on the Earth’s surface, which can cause widespread blackouts. They can also damage satellites in orbits or be a radiation danger to astronauts. In general, though, our magnetic field protects us on the ground, preventing us from suffering any direct danger. And, as a bonus, we can get beautiful displays of aurorae out of them. While they’re a concern for us as an electricity-using and space-faring race, we can protect ourselves from their danger while simultaneously reveling in their power and majesty.

Credit: NASA/GSFC/STEREO; Eric Hines

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- The Sun blasts out a flare and a huge filament
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Tripping the light fantastic | Bad Astronomy

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In the past few months the Sun has come roaring back to life, blasting out flares and fierce waves of subatomic particles. These space storms are caused by the magnetic field of the Sun, which stores huge amounts of energy. Near sunspots the magnetic field lines get tangled and can suddenly erupt, hurling that energy into space.

If these tsunamis of particles head our way, they interact with our own planet’s magnetic field. Through complicated processes, the particles are focused down into our atmosphere, where they light it up (literally) like a neon sign. The result: aurorae, also called the northern (or southern) lights.

During a recent storm, photographer Dave Brosha was up in Yellowknife, in Canada’s Northwest Territories, which is at a latitude of 62° north, not all that far south of the Arctic Circle. The aurora display that night was, well, unearthly. He got some amazing shots, including this one:

[Click to stimulatedemissionate.]

Wow. That’s breathtaking. The silhouette belongs to photographer Thomas Koidhis, also a Canadian from the NWT. The stream of green aurora is simple amazing, like a solid path you could walk right into the sky. The Milky Way hangs as a backdrop, the constellations of Cygnus and Lyra punctuating the glowing stream.

He has many more such gorgeous shots in his Flickr set, and I particularly like this one, which shows the ribbons and curved streamers of the lights, caused by the curves in the Earth’s magnetic field itself.

I’ve said it before, and I’ll say it many more times in the future: people who say science takes away the magic of reality are wrong. The aurorae are among the most beautiful and amazing sights that nature has to offer, and their beauty is enhanced, magnified, by knowing what it is that causes them.

Knowing is half the fun. The other half? Finding out.

Credit: Dave Brosha, used by permission.

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Acoustical Archaeologists Solve the Mystery of the Doge’s Stereo System | 80beats

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church
Saint Mark’s basilica was where many Venetian polyphonic works had their debut performances, but the reverb presented a puzzle for historians.

Ah, the Renaissance—lots of deep thinkers, gorgeous art, busty maidens, fried dough on a stick (if Ren faires are to be believed), and the liveliest music this side of the Middle Ages. But when you compare the elaborate, up-tempo harmonies of late Renaissance polyphony to the churches where they would have been performed, a serious discrepancy pops up. Giant Renaissance churches like Saint Mark’s basilica and the Redentore, both in Venice, have way too long of a reverberation time for those tunes to sound good. It takes a full 7 seconds for a note to fade after it’s played or sung, and that means that songs, especially fast ones, blend into a giant muddy mess.

A physicist and a music technologist, who presented their work at the American Acoustical Society on Monday, wondered if the churches, when packed full of people and hung with heavy draperies during holy festivals, might have sounded much better than they do today. Working with architectural historians, they calculated the chairs, drapery, and audience members’ ability to absorb sound. With a computer model of the churches, they were able to show that with full-on holy regalia and a crowded audience, the reverberation time was cut in half. They took their analysis even further to see if the small pergoli, or balconies, installed by an architect in Saint Mark’s would have enhanced the experience of a person sitting in the Doge’s throne when a choir was split between them (all the rage in Renaissance Venice). Indeed, they found that with a split choir in a fully decorated church, the reverberation time at the Doge’s throne was reduced to a mere 1.5 or 2 seconds, which is the gold standard for modern concert halls.

To hear the Doge’s stereo system for yourself, click here and scroll to the bottom of the page.

[via ScienceNOW]

Image courtesy of Andreas Tille / Wikimedia Commons


NCBI ROFL: Ritter Sport chocolate – check. “When Harry Met Sally” DVD – check. Publication – check. | Discoblog

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Immediate effects of chocolate on experimentally induced mood states.

“In this work two hypotheses were tested: (1) that eating a piece of chocolate immediately affects negative, but not positive or neutral mood, and (2) that this effect is due to palatability. Experiment 1 (48 normal-weight and healthy women and men) examined the effects of eating a piece of chocolate and drinking water on negative, positive and neutral mood states induced by film clips. Eating chocolate reduced negative mood compared to drinking water, whereas no or only marginal effects were found on neutral and positive moods. Experiment 2 (113 normal-weight and healthy women and men) compared effects of eating palatable and unpalatable chocolate on negative mood, and examined the duration of chocolate-induced mood change. Negative mood was improved after eating palatable chocolate as compared to unpalatable chocolate or nothing. This effect was short lived, i.e., it disappeared after 3 min. In both experiments, chocolate-induced mood improvement was associated with emotional eating. The present studies demonstrate that eating a small amount of sweet food improves an experimentally induced negative mood state immediately and selectively and that this effect of chocolate is due to palatability. It is hypothesized that immediate mood effects of palatable food contribute to the habit of eating to cope with stress.”

Bonus quotes from the Materials and Methods:

“To induce mood states, excerpts from popular movies were shown: a sad sequence from “The Champ” in which a boy cries at the death of his father (2:51 min) and a happy sequence from “When Harry Met Sally” in which a woman and a man discuss an orgasm (2:35 min). An emotionally neutral film sequence was used as a control stimulus (a documentary on the processing and usage of copper; 2:02 min).”

“One group of participants (n=24) received a piece of chocolate (5 g), the other group (n=24) a sample of spring water (20 ml, three pieces or three samples in all). They received the chocolate they had chosen before the experiment as most pleasant out of seven types of commercially available chocolates from the same brand (“Ritter Sport”, Alfred Ritter GmbH). Eight participants had preferred milk chocolate, six participants chocolate with hazelnuts, five participants chocolate with cornflakes, three participants milk chocolate with cocoa cream paste, and two participants plain chocolate.”

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Discoblog: NCBI ROFL: Emotional and uncontrolled eating styles and chocolate chip cookie consumption.
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Discoblog: NCBI ROFL: Acronym win: the CHUMP study

WTF is NCBI ROFL? Read our FAQ!


There’s just something about him… | The Loom

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If you’re a regular reader of the Loom, you’re no doubt familiar with the parasite Toxoplasma gondii. If you’re not, now is the perfect time to meet this sinister creature which may very well be residing in your brain. It seems like every year or two, it gets more remarkable, and today it’s taken another [...]


Fort Collins, Colorado talk OF DEATH | Bad Astronomy

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A quick note to folks in the Fort Collins, Colorado area: I’ll be giving my "Death from the Skies!" talk on Thursday, November 3 (tomorrow as I write this) at the Colorado State University campus there. The talk will be at the Lory Student Center East Ballroom at 7:00 p.m.

It’s open to the public [UPDATE: admission is FREE!], so if you’re in the area, come see me show how an asteroid impact can ruin your whole day!


NASA to Develop Dust-Grabbing Tractor Beams for Future Missions | 80beats

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spacing is important
Put ‘er here, R2.

Fans of intergalactic exploration both real and fictional, rejoice: Future NASA missions may incorporate tractor beams, lasers that can pick up objects at a distance. “We’re caught in a tractor beam and it’s pulling us in!” is a long way off, but NASA has just awarded a team of scientists $100,000 to explore three different methods of trapping objects with laser light and reeling them in.

Dust, rather than Corellian light freighters, are the objects in question: the hope is to use tractor beam tech to collect atmospheric particles or grab dust from a planet’s surface without resorting to using a drill, as the Mars rovers have. And indeed, one of the three methods—optical tweezers—has been used by biologists for decades to hold microscopic particles, including viruses and bacteria, in place for experiments.

The challenge will be developing techniques that will work in all the different environments that an exploratory craft might explore. Optical tweezers won’t work in the vacuum of space, for example, but could be useful on a planet with an atmosphere. The other techniques, which use solenoid beams and Bessel beams, could work at a variety of distances and perhaps without an atmosphere—the NASA team will spend the next decade or so exploring how they might be developed and incorporated.

Concept image courtesy Dr. Paul Stysley via NASA


Vampire-like Predatory Bacteria Could Become A Living Antibiotic | 80beats

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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 only grew upon three bacterial species, all of which can cause pneumonia-like disease in humans. A more recent study showed that it can prey upon a wider variety of microbes, most of them potentially pathogenic, like E. coli.
  • These studies also found that M. aeruginosavorus has a knack for disrupting biofilms, the dense collection of bacteria that cause harmful plagues on teeth and medical implants alike, and can be up to 1,000 more resistant to antibiotics than free-swimming bugs.
  • The bacteria can also swim through viscous fluids like mucous and kills Pseudomonas aeruginosa, the bacterium that can colonize lungs of cystic fibrosis patients and form a glue-like film.
  • These qualities have caught the eye of researchers who think it could be used as a living antibiotic to treat biofilms and various types of drug-resistant bacteria, which are a growing problem in medicine. Sequencing the organism’s genome is an important step in understanding its biochemistry and how it preys on other microbes.

Clues From the Vampire Code: 

  • The new study found that each phase of life involves the use (or expression) of different sets of genes. The migratory/hunting phase involves many segments that code for flagellum formation and genes involved in quorum sensing. The attachment phase involves a wide variety of secreted chemicals and enzymes that facilitate the flow of materials from the host.
  • Micavibrio aeruginosavorus possesses no genes for amino acid transporters, a rather rare trait only seen in a few other bacterial species that depend heavily upon their host to help them shuttle these vital protein building-blocks. This absence helps explain the bacterium’s dependence on a narrow range of prey, from which it directly steals amino acids. Although it remains unclear exactly how the microbe attaches to and infiltrates other cells.

The Future Holds:

  • The range of microbes upon which Micavibrio aeruginosavorus can survive is expanding; after being kept in laboratory conditions for years it has apparently evolved a more diverse diet. If this expansion continues, that could be a real problem for its use as an antibiotic; it could begin to eat beneficial gut bacteria, for example.
  • Researchers claim it is harmless to friendly gut microbes, but it hasn’t been tested on all the varieties of bacteria present in humans.
  • Several important steps must be taken before testing in people, like learning more about what traits makes another bacteria tasty to Micavibrio aeruginosavorus. Researchers speculate the bacterium may need to be genetically altered in order to go after specific pathogens, or to reduce the risk of it causing unforeseen complications.

Reference: Zhang Wang, Daniel E Kadouri, Martin Wu. Genomic insights into an obligate epibiotic bacterial predator: Micavibrio aeruginosavorus ARL-13. BMC Genomics, 2011; 12 (1): 453 DOI: 10.1186/1471-2164-12-453

Image credit: University of Virginia