Science Square

  • Issue 81 / May - June 2011



    When it comes to fighting flu, gut bacteria are on our side

    The Fountain

    1- When it comes to fighting flu, gut bacteria are on our side
    Original Article: Ichinohe T. et al., PNAS (published online before print 2011).

    Influenza, also known as seasonal flu, affects up to 5 million people annually. Flu viruses infect and damage the animal respiratory tract, especially the lungs. Upon flu virus infection, a life or death battle between an animal’s immune system and the flu virus begins. To defeat the flu virus, the animal’s immune system synthesizes important flu-fighting molecules. Researchers at Yale University discovered that mice on the antibiotic regimen, a treatment that wipes out certain bacteria which normally live in the guts of the animal hosts, showed deficiency in immune responses against flu virus in the lungs compared to mice that had not been treated. This finding suggests an unexpected link that the bacteria living in the animals seem to control the production of these flu-fighting molecules. These commensal bacteria, or good bacteria, prime the immune system in making flu-fighting molecules even before infection, and this priming is important for subsequent flu-fighting strategies. The exact bacterial species that helps fight the flu are yet to be identified. It is interesting to contemplate why the immune system trusts bacteria with such an important job. Whatever that reason might be this finding warns against misuse or abuse of antibiotics. We don’t want to kill the good bacteria that might just protect us in the next flu season.

    2- Less talking with longer words
    Original Article: Piantadosi S.T. et al., PNAS 108, 3526 (2011).

    What factors affect the length of a word? Do we prefer to use short words or long words while we are talking? For many years, researchers believed that the most frequently used words tend to be short in order to make the language more efficient. It is intuitive when we think of words such as “a,” “the,” “but” and their popularity in our everyday life. However, according to a recent study done by Piandatosi and coworkers in the Department of Brain and Cognitive Sciences at MIT, the length of a word reflects the amount of information it contains. They observed that people use many words in predictable sequences along with other words in their daily life. Most of the time a short word may not contain information per se, but carry information as a collection with other familiar words. This observation led the researchers to look at the problem from an 'information content' perspective. A word is said to have more information if it is less predictable in a sequence. An analysis was done on the Google text database in 11 different languages. The results show that word length closely correlates to information content. Once again, it is not important how much you talk. It is important how much you mean.

    3- Ups and downs of sleep with alpha waves
    Original Article: McKinney S.M. et al., PLoS One 6, e17351 (2011).

    Why do we randomly wake up in the middle of the night? Searching for an answer for this question, researchers at the Massachusetts General Hospital (MGH) discovered a brain rhythm that determines one’s susceptibility to disturbance by the outside world while asleep. Scott McKinney and his colleagues conducted a study where they analyzed the electroencephalographs (EEGs) of 13 volunteers, who spent 3 nights in MGH’s Sleep laboratory. EEG devices use electrodes on the scalp to detect electrical activity in the brain. There are four major brain waves that can be detected by EEG: alpha, beta, delta and theta waves. Alpha waves usually emanate from the back of the head during relaxed wakefulness, particularly when your eyes are closed, and they are thought to gradually disappear when a person goes to sleep. Researchers developed a special computational method that can probe EEGs in much deeper data resolutions. Their analyses revealed that alpha waves never disappear during sleep; they just go below conventional detection levels. Moreover, when alpha wave activity spikes just before an obnoxious auditory stimuli (e.g., loud talking or traffic noise) is played, volunteers seems to wake up more easily than when alpha wave activity was low. These findings suggest that maybe the alpha wave activity is the brain’s way of keeping us aware of our surroundings during sleep, and perhaps it enables us to wake up quickly in case of danger. Of course, too much alpha activity might also have a downside: it can make you a light sleeper and give you restless nights.

    4- Killer whales imitate enemies and friends
    Original Article: Wei B.M. et al., Marine Mammal Science (published online before print 2011).

    In marine mammals, as individuals frequently cannot see each other, sound is particularly important for communication. Killer whales live in groups or clans, and these different clans have their own dialects. A recent study showed that whales can do more than just talk in their own language: they can mimic calls from other groups with a different dialect. While analyzing the social behavior of wild orcas living near Vancouver Island in British Colombia, a group of researchers from the University of Vienna discovered that resident whales occasionally produce call types from the repertoires of other vocal clans. The calls resemble the calls of foreign groups that the original group interacted with before. When different clans are in close proximity, it is quite challenging to reliably distinguish original calls from resembling calls. For this reason, researchers recorded calls that resemble call types of a different clan in the absence of that clan and compared them to the originals of the respective call types by analyzing their sonograms. Sonograms reveal distinctive information about the structure of the sound waves, i.e. the spectral density of these signals, and this information can be used to classify animal sounds. The comparative analysis clearly shows that killer whales can imitate calls from other groups even when members of that group are not around. Researchers suggest that this could be a way of labeling outsiders or keeping tabs on their location. Maybe by impersonating the calls of a group, they are conveying a message about that group to their own family members. It is exciting to see that vocal mimicry is not limited to songbirds and dolphins, and that killer whales have more complex social lives than we previously thought.

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