Science-- there's something for everyone

Wednesday, October 31, 2012

Just for fun: Hominid Animation

What would happen if humans evolved to fill all the ecological niches? Perhaps something like the creepy landscape envisioned by film maker Brian Andrews, who placed human skeletons inside a variety of animal forms. For your Halloween viewing pleasure:

You can see more by Andrews on his website.

Hat tip: Not Exactly Rocket Science.

Tuesday, October 30, 2012

Full color map of the Milky Way bulge

As you know, our galaxy is called the Milky Way. Although we know far more about it than about other galaxies, it has been difficult to catalogue all the stars contained within it, particularly those located in the galactic center. The stars in this region are packed tightly together into a distended bulge that is obscured by dust. Luckily, infrared telescopes can see through that dust. Enter the VISTA telescope and a team of cosmologists led by Roberto Saito of Pontificia Universidad Catolica de Chile, Universidad de Valparaiso and The Milky Way Millennium Nucleus, Chile.

Between 2010 and 2011, the VISTA telescope was used to observe the Milky Way bulge in five different passbands (ranges of wavelengths). This data was compiled to make up the Variables in the Via Lactea (VVV), a public survey of the Milky Way. Saito and his colleagues used the VVV to create the following stunning panorama:


Caption: This striking view of the central parts of the Milky Way was obtained with the VISTA survey telescope at ESO’s Paranal Observatory in Chile. This huge picture is 108,500 by 81,500 pixels and contains nearly nine billion pixels. It was created by combining thousands of individual images from VISTA, taken through three different infrared filters, into a single monumental mosaic. These data form part of the VVV public survey and have been used to study a much larger number of individual stars in the central parts of the Milky Way than ever before. Because VISTA has a camera sensitive to infrared light it can see through much of the dust blocking the view for optical telescopes, although many more opaque dust filaments still show up well in this picture.
Credit: ESO/VVV Consortium Acknowledgement: Ignacio Toledo.

Okay, so it’s not that stunning, as astronomy pictures go. But keep in mind that this is the first single diagram of the entire Milky Way bulge, and that it contains over 84 million stars. 

Saito, R., Minniti, D., Dias, B., Hempel, M., Rejkuba, M., Alonso-García, J., Barbuy, B., Catelan, M., Emerson, J., Gonzalez, O., Lucas, P., & Zoccali, M. (2012). Milky Way demographics with the VVV survey Astronomy & Astrophysics, 544 DOI: 10.1051/0004-6361/201219448

Monday, October 29, 2012

Kids adopted by gay or lesbian couples do just fine

Here’s a result that should surprise no one. High-risk children who are adopted out of foster care by gay or lesbian couples fair just as well as kids adopted by heterosexual couples. This seems so obvious I shouldn’t have to explain the data, but of course, that’s not how science works. So, here it is:

Eighty-two children under age nine who underwent public adoptions in Los Angeles County were examined at two, twelve and twenty-four months post-adoption. Behavior and cognitive ability was assessed at each time point. The kids were also evaluated for differences in their background that could affect behavior or intelligence, such as prior neglect or prenatal substance exposure.

As expected, the kids from the gay households did not differ in any meaningful way from kids in straight households. This was true despite the fact that the children adopted by gay or lesbian couples often had significantly greater background risk factors. All the children benefited equally from adoption, as shown by an average gain of about 10 IQ points after leaving foster care. These data corroborate prior studies demonstrating that children raised by gay or lesbian parents are indistinguishable from those raised by heterosexual parents in attitude, behavior or gender-role development.

In the U.S., over a hundred thousand kids are currently awaiting adoption. Many of these kids have physical or mental health issues, often stemming from whatever landed them in foster care in the first place. Adoption can often mitigate these problems. By all means, let’s widen the pool of potential parents as much as possible. 

Lavner, J., Waterman, J., & Peplau, L. (2012). Can Gay and Lesbian Parents Promote Healthy Development in High-Risk Children Adopted From Foster Care? American Journal of Orthopsychiatry, 82 (4), 465-472 DOI: 10.1111/j.1939-0025.2012.01176.x

Friday, October 26, 2012

Bad news for avoiding prions

Just when you thought prions couldn’t get any scarier, you find out that some birds can pass the infectious proteins intact through their digestive systems. Yes, crows can pick up prions from eating infected meat, and then pass those prions on in their feces. This cheery news is courtesy of Kurt VerCauteren and his colleagues at the United States Department of Agriculture.

Prions are infectious misfolded proteins. Normally, malfunctioning proteins are simply discarded or dismantled, but not so with prions. Upon introduction into a cell, these peptides induce other proteins to misfold as well. In other words, prions are communicable despite having no genetic material. This rampant misfolding results in a number of incurable, deadly neurological diseases known as transmissible spongiform encephalopathies (TSEs). An example would be bovine spongiform encephalopathy, a.k.a. mad cow disease.

Wild animals also succumb to prions and are often scavenged by crows. To test whether prions can be spread by foraging crows, the researchers fed some captured wild American crows the brains of mice infected with prions. The crows’ feces were collected, radiated to kill microbes, diluted, and injected back into mice. 100% of the unfortunate mice treated in this manner came down with TSE. If this doesn’t sound ominous, let me remind you that crows can travel far distances and are indiscriminate poopers.

On the plus side, if you’re not in the habit of ingesting fecal material, you probably don’t have an increased risk of contracting TSE yourself. On the other hand, these data do suggest that it would be nearly impossible to keep prions contained. Short of clearing up every infected carcass before crows or other avian scavengers can get to them, there’s not much we can do.

Kurt C. VerCauteren, John L. Pilon, Paul B. Nash, Gregory E. Phillips, & Justin W. Fischer (2012). Prion Remains Infectious after Passage through Digestive System of American Crows (Corvus brachyrhynchos) PLoS ONE : doi:10.1371/journal.pone.0045774

Thursday, October 25, 2012

Protecting kids from guns

Regardless of one’s feelings about the second amendment, most people agree that it’s important to keep children safe from firearms. The American Academy of Pediatrics (AAP) fully endorses this view. The data clearly show that the safest home for children is one without guns. According to the Centers for Disease Control and Prevention, in 2010, gun violence was the fourth most common cause of injury death among children ages five to fourteen and the second most common cause of injury death in older children. These deaths were divided between homicides and suicides.

No one believes that the 38% of households that currently contain guns will give them up. In lieu of that, there are some sensible measures that could go a long way to protecting children and adolescents from gun violence.

Here are the recommendations from the AAP:

  • Consumer product regulations regarding child access, safety and design of guns.
  • Child access prevention laws that enforce safe storage practices including the use of trigger locks, lock boxes, and gun safes.
  • Regulation of the purchase of guns, including mandatory waiting periods, closure of the gun show loophole, mental health restrictions for gun purchases, and background checks.
  • Restoration of the ban on the sale of assault weapons to the general public.
I strongly favor each of these measures.

Council on Injury, Violence, and Poison Prevention Executive Committee (2012). Firearm-Related Injuries Affecting the Pediatric Population PEDIATRICS DOI: 10.1542/peds.2012-2481

Wednesday, October 24, 2012

Just for fun: Staircase of books

London-based Levitate Architects came up with the following storage solution.


Not only can you use this staircase to reach the upper floor and to store your books, but the skylight above the stairs assures that you can also sit on the steps and read.

Tuesday, October 23, 2012

Ever vigilant dolphins

You may have heard that dolphins sleep with only half of their brains at a time. Like me, you may have assumed that, while the awake hemisphere was capable of preventing the animals from drowning, it wasn’t completely alert. Not so. Apparently, dolphins can respond to echolocation and training cues with full concentration indefinitely. Or at least, for the fifteen straight days demonstrated by this study.

Researchers from marine mammal programs in San Diego, led by Brian Branstetter of the National Marine Mammal Foundation, asked two dolphins (SAY and NAY) to search their water enclosure for simulated echolocation targets. Upon detecting a target, the dolphins could press a response paddle and receive a reward. After training, the dolphins each participated in two 5-day sessions of round-the-clock target simulation. Both of the dolphins maintained a correct response rate of over 75%, but because SAY did a little better (she was correct 95% of the time), she got the honor of participating in a 15-day test. That test was actually supposed to last thirty days, but was cut short by a storm. SAY’s performance remained strong throughout this longer interval.

Credit: Brian Branstetter

During unihemispheric sleep when only half their brains are awake, dolphins are not merely maintaining breathing and other bodily functions. They can respond to their surroundings with full alertness. If you consider that many dolphin populations are at constant risk of attack from sharks, perpetual vigilance sounds like a great idea.

Brian K. Branstetter, James J. Finneran, Elizabeth A. Fletcher, Brian C. Weisman, Sam H. Ridgway (2012). Dolphins Can Maintain Vigilant Behavior through Echolocation for 15 Days without Interruption or Cognitive Impairment PLoS ONE DOI:10.1371/journal.pone.0047478.

Monday, October 22, 2012

Saving species with scent

Catherine Price and Peter Banks from the universities of New South Wales and Sydney may have found a way to protect endangered native species from predators. It seems that predators are less likely to find and kill prey if the hunters have been pre-exposed to the scent of that prey. At least, that was the case for black rats hunting quails’ eggs.

The experiments were conducted in one-hectare square grids in shrubby areas known to contain large black rat populations. These rats were more than happy to raid birds’ nests for eggs or nestlings, though they had not previously encountered quail. The researchers introduced the scent of quail nests (more specifically, feathers and feces) to the test areas. In some cases, the scent was spread around for seven days after which artificial nests containing actual quail eggs were introduced. In other tests, the scent and the nests were imported into the rats’ territories at the same time.

In regions where the quail smells were introduced a week prior to the nests, quails’ eggs had a 62% greater survival rate. In other words, after prolonged exposure to quail smells that were not associated with nests, the rats ceased hunting for quail eggs. In essence, the rats were being taught to ignore quail nest smells.

How would this help in a real world setting? While ecologists probably can’t continuously pipe prey smells throughout natural parks, they might be able to do so for a few days prior to a planned reintroduction of an endangered species. This might give a vulnerable species a head start on reestablishing itself in the region.

Price, C., & Banks, P. (2012). Exploiting olfactory learning in alien rats to protect birds' eggs Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1210981109

Friday, October 19, 2012

Marshmallow test notwithstanding, children are more rational than we thought

You’ve probably heard about the ‘marshmallow test’ for impulse control. Briefly, young children are given one marshmallow and told that if they can delay eating it for a few minutes, they’ll get a second marshmallow. The original experiment was conducted in the 60’s at Stanford University, but cognitive scientists and parents have been repeating the experiment ever since. Here's an example you might enjoy.

Why such interest in whether kids can resist a marshmallow? When those children were revisited later in life, the ones who had been able to delay gratification at age four seemed to have some huge advantages. For example, they had higher SAT scores and suffered from less substance abuse. Apparently, being able to postpone eating a tasty treat as a preschooler has implications for one’s success in life. Or does it? Not so fast.

Celeste Kidd, Holly Palmeri and Richard Aslin of the University of Rochester repeated the marshmallow test, but with a twist. This time, prior to giving children their first marshmallow, they set up scenarios where a facilitator was seen as either ‘reliable’ or ‘unreliable’. Children were offered a handful of crayons or stickers for a project and told that if they could wait, the staffer would go and fetch a much better collection of materials. For one group of kids, the adult did indeed return with some particularly enticing supplies (reliable).  For the second group of children, the adult came back empty handed (unreliable), explaining that there weren’t any more materials after all. After two experiences with the adult being either reliable or unreliable, the kids were presented with their marshmallows and the real test began.

The kids who had been paired with a reliable facilitator were able to wait an average of four times longer than the children who had been twice disappointed by an unreliable adult. This difference may have been underestimated by the fact that each test was terminated after 15 minutes, by which point only one out of fourteen children in the unreliable group but nine out fourteen in the reliable group still had their marshmallow. In other words, many of the kids in the reliable group might have been willing to wait far longer.

While young children clearly have difficulty with impulse control, this study contradicts the view that differences in that control are purely innate. Instead, the data suggest that the majority of young children use a rational process to decide whether or not to wait for a reward. After all, if you can’t trust someone to bring you a second marshmallow, you might as well go ahead and eat the one in front of you.

The University of Rochester researchers explain:

Celeste Kidd, Holly Palmeri, & Richard N. Aslin (2012). Rational snacking: Young children’s decision-making on the marshmallow task is moderated by beliefs about environmental reliability Cognition DOI: 10.1016/j.cognition.2012.08.004

Thursday, October 18, 2012

Your 2012 Nobel prize winners

The 2012 Nobel prizes were announced last week. Here are the winners in physics, chemistry and medicine, complete with video explanations.

Serge Haroche and David Wineland won the physics prize "for ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems". In essence, they showed that, contrary to conventional wisdom, it is possible to observe and measure a single photon of light.

The chemistry award went to Robert Lefkowitz and Brian Kobilka “for studies of G-protein-coupled receptors".  Receptors are protein complexes that span cell membranes. Most drugs work by binding to particular membrane receptors.

The prize for medicine went to Sir John Gurdon and Shinya Yamanaka “for the discovery that mature cells can be reprogrammed to become pluripotent". Normally, when mature cells divide, they can only give rise to more of the same kind of cell. Thanks to the breakthroughs celebrated by this award, researchers can now induce some mature cells to forget their programming and give rise to any kind of cell.

The award ceremony will take place in Stockholm, Sweden on December 10th.

Wednesday, October 17, 2012

Just for fun: Space jump!

On Sunday, Felix Baumgartner performed a record breaking space jump. He jumped from the greatest height ever and was the first to break the sound barrier in free fall. He was carried to a height of 39 km in a capsule suspended from a gigantic helium balloon. He free-fell for over four minutes, reaching a top speed of 1,342.8 km/hour (mach 1.24, or 1.24 times the speed of sound) before his parachute successfully deployed. He even stuck the landing.

Not to say that there weren't some tense minutes. As you can see in the video, he tumbled head over heels for a while before gaining control.

Tuesday, October 16, 2012

Why are some sounds so unpleasant?

Researchers led by Sukhbinder Kumar of Newcastle University have been studying this burning question: why do some sounds make us flinch? We’re not talking about sounds that are so loud that they hurt our ears, but rather sounds we can’t stand even at what would otherwise be comfortable volumes. It turns out that these sounds create a feedback loop between the auditory cortex, which processes sounds, and the amygdala, which is involved in emotion and memory.

Thirteen healthy volunteers were asked to listen to 74 distinct sounds, many of which had been previously judged to be highly disagreeable, while undergoing MRI scans. The subjects rated each sound from 1 (least unpleasant) to 5 (most grating). Activity in both the auditory complex and the amygdala were linked with the unpleasant sounds. The authors believe that the stimulus travels from the auditory complex to the amygdala, where it is given an emotional tag, and then back to the auditory complex. This cycle can be repeated many times, increasing the degree of aversion to the sound.

Since I’m sure you’re dying to know, here are the ten most reviled sounds:

  1. Knife on a bottle
  2. Fork on a glass
  3. Chalk on a blackboard
  4. Ruler on a bottle
  5. Nails on a blackboard
  6. Female scream
  7. Angle grinder
  8. Squealing brakes
  9. Baby crying
  10. Electric drill
I don’t know about you, but just typing that list set my teeth on edge. 

Sukhbinder Kumar, Katharina von Kriegstein, Karl Friston, & Timothy D. Griffiths (2012). Features versus Feelings: Dissociable Representations of the Acoustic Features and Valence of Aversive Sounds Journal of Neuroscience DOI: 10.1523/JNEUROSCI.1759-12.2012

Monday, October 15, 2012

Whole genome sequencing in 50 hours

There are thousands of genetic diseases, many of which are lethal in untreated newborn babies. Unfortunately, the conventional whole genome sequencing (WGS) methods required to detect these defects can take up to six weeks—time that infants may not have. Thanks to the efforts of more than twenty authors (and countless other people) from Children’s Mercy Hospital and two universities in Kansas City, MO, WGS can now be done in just over two days.

Several innovations were responsible for this great decrease in time. First, sample preparation time was decreased from sixteen hours to only 4.5 hours. The sequencing itself, which used to take well over a week, was reduced to just over one day. Finally, the subsequent analysis time was likewise drastically reduced. By combining these time saving factors, the researchers were able to successfully complete WGS on several infants in only fifty hours. Because much of the work was fully automated, only five of those hours required human involvement.

Although many genetic diseases can be managed with prompt and proper care, there are sadly many others for which any treatment is futile. However, even in cases where an infant has an inevitably fatal illness, parents may still benefit from knowing sooner rather than later. In some cases, rapid WGS might quickly rule out suspected genetic diseases, or help researchers find genetic connections for diseases with unknown causes. For these reasons, this new technique will probably find wide use in hospitals.

Carol Jean Saunders, & et al (2012). Rapid Whole-Genome Sequencing for Genetic Disease Diagnosis in Neonatal Intensive Care Units Science Translational Medicine DOI: 10.1126/scitranslmed.3004041

Friday, October 12, 2012

Revenge of the ant slaves

Some species of ants will raid the nests of rival ants, kill or drive off the adults and carry the babies back to their own nests. Once imprisoned in the conquerors’ nest, the baby ants are put to work caring for their new ruling class. Enslaving ants in this way is a form of ‘brood parasitism’. You may be more familiar with this term as it relates to cuckoos laying their eggs in other birds’ nests. Just as the host birds rear young that is not their own, so too must the enslaved host ants rear unrelated parasitic ants.

File:Protomognathus americanus casent0003235 profile 1.jpg

File:Temnothorax longispinosus casent0104819 profile 1.jpg

Top: Parasitic slave-maker Protomognathus americanus
Bottom: Enslaved Temnothorax longispinosus
Photo by April Noble
Both pictures courtesy of

Slave-making ants are well equipped for warfare with their fellow ants, but not so well prepared to care for themselves. In some cases, their nests are entirely dependent on the foraging and caretaking abilities of their enslaved conquests. To some degree, this puts them at the mercy of their slaves. According to Tobias Pamminger and his colleagues from the Gutenberg University of Mainz and the Ludwig Maximilian University of Munich, the slaves can rebel by refusing to care for their ‘masters’.

In fact, the researchers found that only half as many pupae in the slave makers’ nests survive as pupae in undisturbed host nests. In other words, host workers make perfectly capable nurses when it suits them, but make little effort to rear the parasitic offspring of their slavers. They may neglect those young or even actively slaughter them.

What’s interesting about this is that the enslaved workers can gain no direct benefit from their ‘slave rebellion’. They can never escape and they can never reproduce. On the other hand, their fellow hosts do benefit if the slaver nest is weakened. By decreasing the number of parasitic slave makers, the enslaved hosts could be protecting other members of their species from the same fate. Apparently, this form of ‘kin selection’ is enough to make the slave rebellion trait a widespread phenomenon.

Tobias Pamminger, Annette Leingartner, Alexandra Achenbach, Isabelle Kleeberg, Pleuni Pennings, & Susanne Foitzik (2012). Geographic distribution of the anti-parasite trait ‘‘slave rebellion’’ Evolutionary Ecology DOI: 10.1007/s10682-012-9584-0

Thursday, October 11, 2012

High blood pressure in pregnancy may affect the baby’s IQ

About ten percent of women experience some sort of hypertensive disorder, such as pre-eclampsia, while pregnant. Unfortunately, according to fourteen Finnish scientists, led by Soile Tuovinen of the University of Helsinki, high blood pressure during pregnancy is associated with lower cognitive ability in the resulting boy babies. I’m sure that knowing this will in no way affect the blood pressure of expecting mothers.

The researchers used data from the Helsinki Birth Cohort Study. About 900 men who were born between 1934 and 1935 had undergone cognitive ability tests when they were twenty (prior to compulsory military service). Boys whose mothers had had high blood pressure while they were pregnant had slightly lower cognitive scores than boys whose mothers had had normal pregnancies. When retested at age 68, men from normal pregnancies showed no change in cognitive ability, but men from hypertensive pregnancies showed a slight decline in cognitive ability. By the way, this isn’t to suggest that women are not similarly affected. They just weren’t part of this study.

Even if this connection between hypertension and IQ does hold true, I don’t think it warrants any extra treatment or paranoia. For one thing, because hypertensive disorders are potentially very dangerous to the mother, pregnant women should already be having regular prenatal screenings to detect and treat any such conditions. For another, the differences in cognitive ability were not great. But as ever, check with your doctor if you have any concerns. 

Soile Tuovinen, Katri Raikkonen, Eero Kajantie, Markus Henriksson, & et al. (2012). Hypertensive disorders in pregnancy and cognitive decline in the offspring up to old age Neurology DOI: 10.1212/WNL.0b013e31826e2606

Wednesday, October 10, 2012

Just for fun: 3D tilt displays

When I heard that 3D display screens were coming to tablet computers, I wasn't expecting this. I'm not sure this is ready for prime time yet, but judge for yourself:

The 'Tilt Display' shown above was developed by researchers at the University of Bristol.

Tuesday, October 9, 2012

Splitting water

Ever wish you could split a drop of water cleanly in two? Well, thanks to the advances of Ryan Yanashima and his colleagues from Arizona State University, that dream may now be a reality.

Ordinarily, if you try to cut a water droplet precisely in half, the original drop shatters into multiple, and often unusable, droplets. However, if you make your knife ‘superhydrophobic’, meaning that water can’t stand to touch it, the droplet will slice cleanly in two. To create these water-hating knives, the researchers began with polyethylene knives and then attached hydrophobic solvents in a several step procedure. You can see the result below.

This just leaves one question: why would you need to chop a water drop in half? There are actually a lot of medical and industrial uses. The important difference between this method and shattering a drop is that by slicing the droplet in half you don’t lose any volume. Remember, anything in the droplet (dissolved medicines, solvents, proteins, etc) will also be divided. Not only the water, but also your valuable ingredients are lost in the satellite droplets you create by fragmenting a drop of your favorite solution. In contrast, you save every bit of material by slicing your water.

Ryan Yanashima, Antonio A. García, James Aldridge, Noah Weiss, Mark A. Hayes, & James H. Andrews (2012). Cutting a Drop of Water Pinned by Wire Loops Using a Superhydrophobic Surface and Knife PLoS ONE : doi:10.1371/journal.pone.0045893

Monday, October 8, 2012

A 1.5 million year old meat diet

Humans were already eating meat on a regular basis one and a half million years ago. You may be surprised to learn how an international team of paleontologists reached this conclusion. It wasn’t just physical evidence in the form of butchery marks on bones, though we do have such clues. No, it was a case of 1.5 million year old malnutrition.

The scientists found the ancients skull fragments of a two-year child suffering from porotic hyperostosis. This disease is often associated with iron-deficiency anemia. In very young children, it is often caused by a vitamin B12 deficiency, either in their mother’s milk or in their own post-weaning diets.

Vitamin B12 is one of the few nutrients that people on strict vegetarian diets (no animal products of any kind) usually need to supplement. This is because it’s not found in plant sources, unless those sources have been artificially fortified. The fact that this unfortunate child likely died of what’s essentially a meat deficiency strongly suggests that meat was a routine and critical part of his community’s diet.

A fragment of a child's skull discovered at Olduvai Gorge, Tanzania, shows the oldest known evidence of anemia caused by a nutritional deficiency. DOI: 10.1371/journal.pone.0046414

Manuel Domínguez-Rodrigo, Travis Rayne Pickering, Fernando Diez-Martín, Audax Mabulla, Charles Musiba, et al. (2012). Earliest Porotic Hyperostosis on a 1.5-Million-Year-Old Hominin, Olduvai Gorge, Tanzania PLoS ONE DOI: 10.1371/journal.pone.0046414

Friday, October 5, 2012

Change deafness

When something suddenly appears in our visual field, we usually notice right away. That isn’t the case when something changes or disappears. Even though the difference is equivalent, it takes us a lot longer to register the loss or alteration of an object within our field of view. This phenomenon has been termed ‘change blindness’. You can see an example here.

Apparently, the same is true for our sense of hearing. University College London researchers led by Francisco Cervantes Constantino tested people for ‘change deafness’. They played specific sets of 4 to 14 pure tones for groups of people with normal hearing. Each auditory scene lasted from two to four seconds. In some trials, a tone was either added or subtracted partway through the sound-scape. You can see a visual representation of these trials below.


No change: the scene was played unaltered.
Change-disappear: A single tone was removed.
Change-appear: A single tone was added.

Participants did significantly better at detecting when a tone was added than when one was subtracted. As more tones were added to the original mix, people became worse and worse at noticing the disappearance of one sound. In contrast, the subjects were close to 100% accurate in detecting the addition of a new tone even when listening to fourteen other notes. People were also far more adept at identifying exactly which tone had been added than which had been removed.

It’s not surprising that we’re attuned to pick up the commencement of new sounds in our environment. After all, a sudden sound may augur the arrival of a predator or other danger. However, it is interesting that we’re much less likely to notice the cessation of sounds. Anyone with a young child can tell you why this can be problematic. 

Francisco Cervantes Constantino, Leyla Pinggera, Supathum Paranamana, Makio Kashino, & Maria Chait (2012). Detection of Appearing and Disappearing Objects in Complex Acoustic Scenes PLoS ONE : doi:10.1371/journal.pone.0046167

Thursday, October 4, 2012

Fighting colony collapse disorder

By now, everyone has heard of the catastrophic losses to honeybee populations due to a phenomenon known as ‘colony collapse disorder’. While environmental factors such as pollution and pesticides have been implicated, one of the leading causes is probably infection by a parasitic mite named Varroa destructor.

A Varroa destructor attached to the back of a honeybee
By Waugsberg, 6/3/2007.

Luckily, bees have evolved some mechanisms for mitigating V. destructor infestations. One such method is called hygienic behavior (HB). In essence, it involves uncorking infected larvae from their sealed brood cells and chucking the sick babies out of the hive. However, not all bees or colonies of bees display the same degree of HB. If apiarists could breed for greater hygiene activity, they might be able to protect their bees from colony collapse.

The first step in creating a resistant bee colony is to find a genetic correlation with HB. To that end, University of British Columbia entomologists led by Robert Parker examined protein expression in bees from a variety of hives. They particularly looked at proteins produced within the antennae of nurse bees. After all, it’s the nurse bees that handle the larvae, and they presumably use their antennae to distinguish between the sick and healthy larvae. The researchers also determined the protein composition within the exoskeletons of larvae, the first line of attack for mites.

The entomologists did find specific proteins that correlated with high levels of HB, most notably factors that stimulate antimicrobial activity and clotting. As more data is collected, beekeepers might be able to use the information to stave off local extinctions in their hives.

Robert Parker, Marta Guarna, Andony Melathopoulos, Kyung-Mee Moon, Rick White, Elizabeth Huxter, Stephen Pernal, & Leonard Foster (2012). Correlation of proteome-wide changes with social immunity behaviors provides insight into resistance to the parasitic mite, Varroa destructor, in the honey bee (Apis mellifera) Genome Biology DOI: 10.1186/gb-2012-13-9-r81