IN THIS ISSUE .
April 21, 2010
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Early on, this Arabidopsis plant embryo picks sides: While one end will form the shoot, the other will take root underground. Short pieces of RNA in the bottom half (blue) make sure that shoot-forming genes are expressed only in the embryo's top half (green), eventually allowing a seedling to emerge with stems and leaves. Like animals, plants follow a carefully orchestrated polarization plan and errors can lead to major developmental defects, such as shoots above and below ground. Because the complex gene networks that coordinate this development in plants and animals share important similarities, studying polarity in Arabidopsis—a model organism—could also help us better understand human development. Courtesy of Zachery R. Smith, a graduate student in the Jeff Long lab at the Salk Institute for Biological Studies.
Creatures like salamanders, lizards, flatworms and starfish can regenerate body parts. Now, scientists have identified a gene that may enable regeneration in mammals. A team led by immunologist Ellen Heber-Katz at the Wistar Institute found that mice lacking p21—a gene that regulates cell cycle—can replace lost or damaged tissue without scarring. The researchers previously discovered that a certain strain of mice could completely heal pierced ears, and the current study proved that p21 was inactive in these rodents' ear cells. The latest finding suggests that scientists one day might be able to enhance the healing process in humans.
This work also was supported by NIH's National Cancer Institute.
Heber-Katz profile (no longer available)
Article abstract (from the March 30 issue of PNAS)
Severe physical injury can elicit the same overblown inflammatory response as bacterial sepsis, an observation that has long puzzled scientists. Now, researchers led by trauma surgeon Carl Hauser of the Beth Israel Deaconess Medical Center think they may have an explanation. After an injury, mitochondria—cellular organelles believed to have originated from bacteria—can spill into the bloodstream. The researchers' results indicate that mitochondria look enough like bacterial invaders to trigger an immune reaction. They also suggest that using antibiotics to treat this trauma-based inflammation may be useless and that finding ways to tackle the immune system directly may be more effective.
Nature is shaped by competition for resources like food and mates. Our bodies are no different—molecular competition affects every aspect of our physiology, from our blood pressure to how our dinner gets digested. Scientists led by Stanislav Shvartsman, a systems biologist at Princeton University, discovered a new biochemical competition that influences the function of an enzyme known as MAPK. Several molecules compete for binding space on MAPK, which is critical for embryonic development in all plants and animals. The contest has high stakes—its winners influence not only the development of our organs, but also how cancer might spread.
Fun fact: Your census results will help computer scientists model how infectious diseases spread across the United States. As part of NIGMS' Models of Infectious Disease Agent Study, research geographer Bill Wheaton at RTI International transformed 2000 census data into a complete synthetic population that has the same demographics as every town, county and state. He and his team will update the population with 2010 census data. Researchers can integrate the population into computer models to better simulate outbreaks and find the best ways to intervene. Plus, having the population on hand can help modelers and policymakers keep pace with real outbreaks.