Issue 74 / March - April 2010
Original Article: Lieberman, D.E. et al., Nature 463, 531 (2010).
The modern running shoe was not invented until the 1970s. However, the presumption that running barefoot is dangerous and causes pain could be wrong. To explain this phenomenon, scientists studied three groups of people in the United States and Kenya: those who had always run barefoot, those who had always worn shoes, and those who had converted to barefoot running from shod running. They found a striking pattern: the three groups positioned their feet differently; while most shod runner people made initial contact with the ground heel-first (rear-foot striking), barefoot runners used their flat feet (mid-foot striking) or the lateral ball of the feet (fore-foot striking) first. Kinematic and kinetic analyses showed that barefoot runners who used the fore-foot or mid-foot strike generated smaller collision forces than the rear-foot strikers with shoes. This means that it is possible to run barefoot on the worldâ€™s hardest surfaces without experiencing the slightest discomfort or pain; all one needs is a few calluses to avoid damaging the skin. It is also clear that running-shoe companies and other footwear designers should pay more attention to how God designed our body and redesign more appropriate shoes for running.
The Molecule with a Thousand Faces
Original Article: Ehre D. et al., Science 327, 672 (2010).
Water freezes at 0 Câ€¦ or perhaps not? Pure water can remain in liquid form at temperatures down to â€“40 C, which is known as a â€śsupercooledâ€ť state. When agitated by stirring or adding impurities, supercooled water freezes instantly. A team of scientists report that under certain conditions, supercooled water freezes when warmed up (!). Supercooled water can freeze at a higher temperature on a positively-charged surface than it does on a negatively-charged one. Initially, the surface is negatively charged at a lower temperature. The surface becomes positively charged when warmed up and the supercooled liquid water solidifies. Will the day ever come when we will be able to understand the water molecule completely? This is something we just donâ€™t know. What we know for certain though is that water, which is apparently the â€śmost normalâ€ť substance around us, has already proven itself ironically as one of the most unusual ones in nature. We take this familiar molecule for granted within our daily routine, but H2O-or water as we know it-still remains a celebrity in the eyes of scientists.
Cancer-Causing DNA Mutations Are Deciphered
Original Articles: Pleasance, E.D. et al., Nature 463, 184 & 191 (2010).
DNA mutations are changes in the DNA code caused by external or internal agents known as mutagens. Scientists have identified mutations from lung cancer and skin cancer and have compared them to normal samples in order to find the mutations that lead to these cancers. They have identified ~23,000 mutations in lung cancer (small-cell lung cancer) and ~33,000 mutations in skin cancer (melanoma). The researchers revealed that most of these mutations are single-base DNA changes, suggesting that they are a direct cause of the carcinogens in tobacco smoke and UV light. Under normal conditions, our cells are equipped with a â€śDNA repair mechanismâ€ť which detects any changes in the DNA code and repairs it. However, when excess amount of mutations occur due to tobacco smoke in our lungs or to too much exposure to sunlight in our skin cells, the DNA repair mechanism cannot repair all of the mutations. Accumulations of these mutations lead to cancer-a state in which cell division has gone out of control. Scientists have calculated that every 15 cigarette causes one mutation in the DNA. These studies will be immensely useful for understanding the reasons behind the genetic changes in cancer and more importantly they will provide a comprehensive catalogue of mutations that can be used for cancer diagnosis and treatment.
Scientists Inspired by the Spider Web
Original Article: Zheng, Y. et al., Nature 463, 640 (2010).
Even though spiders may not be the most appealing creatures living on earth, they are one of the most intriguing predators in the animal kingdom. For centuries the intricate ways that spiders hunt, their (relatively) enormous appetite, their strong senses and extraordinary craftsmanship have been fascinating research topics for scientists. In this study, researchers wondered why and how spider webs become decorated with pearl-like drops of water in humid weather conditions. At nanometric scales, the group revealed that the fibers which constitute the web of Uloborus Walkcenaerius-a non-venomous spider-change conformations after interacting with water. When the web becomes wet the fibers condense into knot-like structures which are distributed evenly along the entire silk. The geometric structure of the web results in surface-energy gradients that drive water particles towards the knots. Concentrating water molecules at the knots may help to keep the rest of the web dry, which is a necessary factor to capture prey. This extraordinary finding has inspired the building of an artificial spider silk, which exploits the same geometric trick, trapping and transporting water droplets. In the near future, such â€śgreenâ€ť materials could be used in a wide variety of applications, such as filtering substances out of chemical reactions without need for a catalyst.
Self-Sacrificing Mother Yeast Cells
Original Article: Liu, B. et al., Cell 140, 257 (2010).
Humanity has always searched for the fountain of youth. Yet, the process of aging is still a poorly understood concept in biology. How ironic that the budding yeast, a mere single cellular organism, has a fascinating way of keeping its offspring young and healthy. It was previously shown that protein aggregates appear within the cytoplasm of yeast cells as they age. These protein aggregates are thought to be toxic to the cells and thus potential risk factors to both mother and daughter cells. Researchers demonstrated that these aggregates are consistently transported to the mother cell, thereby allowing the daughter cells to make a fresh start to life. Polymerizing actin filaments, which are nucleated from the polarisome in the daughter cell, bind to these aggregates and push them towards the mother cell cytoplasm. In addition to being an amazing biological process, these self-sacrificing mother cells which keep their offspring healthy form a controversial issue. The common understanding in biology is that all organisms struggle for their own survival. However, why a simple organism like yeast prefers to have a healthy daughter cell and to jeopardize its own life is unclear and shows the existence of a motherâ€™s mercy, even at the single-cell level.
Honey Bee Collapses
Original Article: Ratnieks, F.L.W. & Carreck, N.L., Science 327, 152 (2010).
Throughout history an extensive loss of honey bee colonies has occurred in many different locations; however, in North America, particularly after 2006, there has been an increase in the disappearance of adult honey bees from hives, in which they abandon their food and brood; this has been coined a â€śColony Collapse Disorderâ€ť (CCD). The most likely cause of the syndrome is seen to be the presence of a parasitic mite Varroa destructor. It is not the mite that causes bee death, but rather the number of bee viruses which it carries, such as the Israeli acute paralysis virus; it was previously thought that these were insignificant to honey bee biology. It has also been suggested that CCD is not caused by a previously unknown pathogen, but rather a combination of factors, which only have subtle effects on bee health if considered separately. The health of honeybee colonies is vital for agriculture. In 2000, the total U.S. crop value wholly dependent on honey bee pollination was estimated to exceed $15 billion. The sudden disappearance of honey bees and the complexity of the causes behind CCD remind us of the delicate balance that exists in nature.