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Science Square (Issue 87)
May 1, 2012

1- Early exposure to microbes shows benefit that is life long

Original article: Olzsak T. et al, Science (2012, epub ahead of print)

It has been known by epidemiologists that people who grew up in farms are less likely to acquire immune diseases such as asthma, allergies, inflammatory bowel disease and multiple sclerosis when compared to people living in cities. Such observations have been the roots of "hygiene hypothesis," which essentially points out the beneficial effects of being exposed to infectious agents. Supporting this theory, a recent study at Harvard Medical School showed that exposure to symbiotic bacteria has a long lasting beneficial effect on the immune system development. "We as a species are not exposed to the same germs that we were exposed to in the past," said the co-author Dennis Kasper, a microbiologist at Harvard Medical School in Boston. In this study, published in Science, the researchers compared germ-free mice to mice with normal bacterial flora. Germ-free mice showed significantly higher levels of invariant natural killer T (iNKT) cells in their colons and lungs. "We made the serendipitous observation that these cells were dramatically enriched in the lung and colon in mice that lacked any microbes," said the co-author Richard Blumberg, the chief of gastroenterology at Brigham and Woman's Hospital in Boston. Body's own production of elevated iNKT cells correlated with higher susceptibility to inflammatory bowel disease and allergic asthma in germ-free mice. Most strikingly, the study showed that exposure to these bacteria in late age did not lower the susceptibility to these immune diseases, indicating that the bacterial exposure needs to be early in life to boost the immune system. After all, broad-spectrum antibiotics for babies may not be such a good idea.

2- Giant chickens of Jurassic Park

Original article: Xu X. et al, Nature 484, 92 (2012)

Many of us undoubtedly learned a lot about dinosaurs from the famous Sci-fi movie Jurassic Park, but who would have imagined that some gigantic feathered dinosaurs would be running along with our favorite monster T-Rex? Paleontologists have recently made an incredible discovery in Liaoning Province of China. They found a set of perfectly preserved fossils that belong to a previously unknown species of dinosaurs. These 125-million-year-old feathered giant dinosaurs represent the largest feathered animal species ever lived on earth. The adult one is predicted to be at least 9 meters (30 feet) long with a weight of 1400 kg (~3000 pounds), which is approximately 40 times bigger than the Beipiaosaurus, largest known feathered dinosaur. New gigantic feathered dinosaurs are given a Chinese-Latin name Yutyrannus huali meaning a "beautiful feathered tyrant." Simple filament like structures as well as the relatively small sizes of feathers seem more similar to feathers from a baby chick than the plumes of an adult bird, suggesting that Yutyrannus used feathers not for flying but for body temperature insulation, perhaps under the harsh climate conditions of that age. Paleontologists are really excited to see that how much more we have learned about dinosaurs over last 15 years and they predict that many different feathered meat-eating dinosaurs lived before and they are still yet to be discovered.

3- Stardust mystery revealed

Original article: Norris B.R.M. et al, Nature 484, 220 (2012)

Heavy elements are formed in the cores of stars and are crucial in formation of celestial structures like our earth. When an intermediate-mass star dies, it triggers a cosmic sandstorm that lasts thousands of years ejecting more than half of its mass into space. Our Sun is expected to go into a similar phase in around 5 billion years. Scientists observed these sandstorms for years but it was a mystery how these particles found could leave the vicinity of the stars and find their way into interstellar space. Computer simulations hinted that these sand-like particles could not be that small, otherwise they would be evaporated by the immense heat of the dying star. Scientists using the Very Large Telescope in Chile had a chance to explore these stars in a greater detail and discovered that the size of these particles is around a micrometer. This size might seem very small to us but for these particles, it is large enough to behave like mirrors for the light rays coming out of the star instead of absorbing them. Since light also behaves like a particle, the momentum transferred by this reflection helps particles to accelerate to the speeds like 10km/second. As the lead author of the study, Barnaby Norris from University of Sydney says: "The dust grains are like lots of little sails catching the wind, or in this case, starlight." The material that comes out of the stars is recycled during the formation of new stellar objects like our old planet.

4- Babies understand more than we think

Original article: Bergelsona, E. & Swingley, D., P.N.A.S. 109, 3252 (2012)

Most babies do not say a meaningful word until they are a year old. It was not clear whether they knew the meaning of the words prior to the speaking age. It is easy to ask the question on whether the babies understand words but it is hard to scientifically measure it. The researchers from the University of Pennsylvania devised an ingenious experiment to test the hypothesis whether the 6-9 months babies understood the common words. During the experiment babies sat on their parents' lap in front of a computer while some images of body parts or foods were shown on the screen. The parents were given instructions through headphones about what to say to the baby about the image on the screen. Babies were monitored by an eye-tracking device to measure their attention being directed to screen. The researchers designed a control environment by pairing a body part and a food item. For instance, if a banana and some hair were shown on the screen, the researchers measured the time that the baby fixated on the banana when the parent instructed the child to look at the banana versus when the parent instructed the baby to look at the hair. 33 infants of ages 6 to 9 months and 50 toddlers of ages 10 to 20 months were recruited for this study. The study convincingly showed that the babies fixated longer on an object when they were instructed to do so. Moreover, as the age of the babies increased the period of fixation stayed pretty much constant until 14 months, but jumped dramatically afterwards. The reason behind the jump in 14 months begs further research. Now, the researchers want also to test the vocabulary of the babies and whether the babies also understand the abstract concepts.