Explaining the adjuvant

Vaccines require the use of an adjuvant, or booster, to achieve maximum effects. The most common type of adjuvant in human vaccination is alum (pictured left), but despite its wide use for the past 90 years, its mechanism of action was not understood. Yan Shi and his colleagues from the University of Calgary have now remedied that situation. It turns out that alum binds to and activates dendritic (D) cells.

During an immune response, it’s the job of D cells to engulf antigens and transfer them to the D cell surface. The antigens are thus presented to the other immune cells, including those involved in antibody manufacture. Without an adjuvant, the antigens in vaccines are only poorly uptaken by the D cells. By using a new technique called single cell force spectroscopy, the team was able to show that alum binds very strongly to the D cell membrane. This binding alters the D cell plasma membrane so that it now readily absorbs antigens.

This new data may lead to even more effective vaccines.

Sperm whales have names

It has long been known that whales can sing complicated and extemporaneous songs. Apparently, that’s not all they can do. According to a new study by Luke Rendell and his team from the University of St. Andrews and from Dalhousie University, it appears that sperm whales (Physeter macrocephalus) begin each speech with an identifier. To put it another way, whales may have names.

Sperm whales routinely make short sequences of clicks called ‘codas’. Back in 2008, Rendell and his colleagues showed that whales sing overlapping and/or matching codas to each other. This time, the researchers focused on a specific five click long coda known as 5R. Closer acoustical comparison showed that each whale had a unique 5R signature composition. Not only that, but the 5R coda tended to occur at the beginning of longer strings of clicks or calls.

Although Rendell stresses that this work is in the preliminary stages, it’s hard not to conclude that the whales are giving their ‘call signs’ before each communication.

Sperm Whale picture by cianc.

Hat tip: The Skeptics’ Guide to the Universe.

Love hurts

Emotional pain produces the same physiological experiences as physical pain, according to a study by researchers from the Universities of Michigan and Colorado, and Columbia University. At least, both types of pain activate the same regions of the brain.

The scientists, led by Ethan Kross of the University of Michigan, recruited a select group of volunteers: people who had suffered a romantic break-up within the past six months that left them feeling rejected. Forty participants were found that fit those requirements. These unfortunate individuals were then subjected to both physical and emotional pain, all while being hooked up to fMRI machines to scan their brains.

For the emotional tests, the volunteers were shown pictures of either a good friend and asked to think of positive moments with that person, or of their ex-partner and asked to think about their recent break-up. The physical pain tests involved the application of heat (up to the sensation of holding a very hot cup of coffee) to an area on their forearms.

The same regions of the brain were involved in both physical and emotional distress. On the other hand, thinking pleasant thoughts about a friend did not stimulate that region. In other words, an agonizing social experience activates the areas of the brain associated specifically with pain, rather than those associated with other emotional content.

A person who has been abandoned by a loved one may not actually have a broken heart, but they may very well be experiencing real physical pain.

The evolutionary roots of prejudice

Humans automatically classify other humans as members of the ‘ingroup’ (belonging to the same clan, religion, race, caste or nationality) or members of ‘outgroups’ (outsiders, who are viewed with suspicion). Why do we divide people up in this manner? According to research led by Laurie Santos from Yale University, we evolved that way. Santos and her colleagues based their conclusion on the fact that rhesus macaques (Macaca mulatta), monkeys with which we shared a common ancestor 25 million years ago, display the same prejudices.

The scientists made use of the stare test I’ve written about before. Like humans, macaques will stare longer at unusual or threatening images than at mundane, peaceful ones. When shown pictures of other macaques, the monkeys started longer at members of other troops than at monkeys within their own groups. It isn’t too surprising that monkeys would stare longer at unfamiliar faces. I can’t say the same about the next experiment though.

This time, the researchers showed the monkeys paired photos including a monkey’s face and an object that monkeys either desire or abhor. For example, a pair might include a face and a piece of ripe fruit, or a face and a spider. This time, the monkeys stared the longest at outgroup faces paired with good objects. In other words, if an outsider was associated with something bad, or a troop member was seen next to a nice item, that was considered normal. To see an outsider paired with something nice seemed a little weird to the monkeys.

Humans show the same kinds of proclivities for associating good things with ingroup members and bad things with outgroup members. Apparently, we come by that strategy naturally. You can test your own inherent prejudices about groups of people by taking an implicit attitude test.

Manipulating molecules with light

Researchers from Johns Hopkins University and from the University of Tokyo have used light to move and manipulate molecules within an intact human cell. Here’s how they did it.

First, they made use of a photocaging method to control whether a substance could enter the cell at all. To do so, they attached a photosensitive chemical to the target enzyme rapamycin. The combined molecule is too large to pass through the cell membrane but upon UV irradiation the photosensitive cage is released and the now smaller rapamycin molecule can freely enter the cell. Among other functions, rapamycin is a 'dimerizer' (an enzyme that induces other proteins to pair up).

Next, they modified two other proteins (A and B) such that if they were to pair up, the combination would translocate from the center of the cell to the plasma membrane. One of these two proteins induces ‘membrane ruffle formation’, a key feature in cell migration. Thus, if the protein complex did move from the interior of the cell to the edge, that displacement could be detected in a microscope by observing the cell membrane structure.

When the researchers shined a UV light on a small region of the cell, they got membrane ruffles just in that region. The UV light was breaking up the photocage around the rapamycin, the rapamycin was entering the cell and dimerizing A and B, and these combined proteins were shuttling to the edge of the cell and causing visible membrane ruffles. The researchers were able to direct where on the cell membrane the A/B dimer appeared by controlling where they shone their light.

Ultimately, the scientists hope to attach a third, target protein to the A/B complex. In that case, the above method would allow the biologists to move that protein of interest to different locations in the cell for study. If different protein dimers that relocate to different specific cell regions could be used, that would make the technique even more useful.

Just for fun: Infinite photo

The folks at National Geographic have done it again. They have the following 'National Parks Infinite Photo' posted on their website.

But don't just look at it here. Go to the link above and click within the yellow box (which you can move to any area of the photo). Each click zooms you in closer and brings up new pictures. You can literally never run out of things to see.

Hat tip: Bad Astronomy.

Why birds collide

Ever wonder why birds smash into objects when flying? Graham Martin of Birmingham University did. He recently published a study in the journal IBIS (guess what that journal specializes in) exploring that topic.

According to Martin, the tactics we use to make obstacles visible to us simply don’t work on birds. For one thing, birds may spend very little of their flying time looking straight ahead. Instead, they may be scanning the ground for prey, or looking around them to evade predators. Unless they live in deep forests, they may have little evolutionary experience with encountering obstacles in mid-flight. Even if they do spot such an object, they may have difficulty interpreting its significance, especially if their visual acuity is not sharp directly in front of them. And finally, birds may not be able to process the stimulus of an unexpected object in their path quickly enough to change air speed or course.

These are not trivial problems for bird populations. It’s estimated, for example, that up to a third of some endangered species perish by colliding with power lines. Calling attention to such obstacles with markers like flapping flags that would be obvious to humans does not seem to be helping the birds. Martin suggests that signals on the ground that divert birds from approaching obstacles may be more effective. Unfortunately, apart from avoiding known flight paths, there doesn’t seem to be that much we can do to attract the birds’ attention to the problem.