In eukaryotes - the group of organisms that include humans - a key to survival is the ability of certain proteins to quickly and accurately repair genetic errors that occur when DNA is replicated to make new cells. In a paper published in the December 23, 2011 issue of the journal Science, researchers at the Ludwig Institute for Cancer Research and the University of California, San Diego School of Medicine have solved part of the mystery of how these proteins do their job, a process called DNA mismatch repair (MMR). "One of the major questions in MMR is how MMR proteins figure out which base in a DNA mispair is the wrong one, " said Ludwig Institute assistant investigator Christopher D. Putnam, PhD, an adjunct assistant professor of medicine at UC San Diego. "For example, if guanine (G) is inappropriately in a base-pair with thymine (T), is the G or the T the error?
Treatment that increases brain levels of an important regulatory enzyme may slow the loss of brain cells that characterizes Huntington's disease (HD) and other neurodegenerative disorders. In a report receiving advance online publication in Nature Medicine, a Massachusetts General Hospital (MGH)-based research team reports that increased expression of Sirt1, one of a family of enzymes called sirtuins, in the brain of a mouse model of HD protected against neurodegeneration. They also identified a potential mechanism for this protective effect. "Diseases such as Huntington's, Parkinson's and Alzheimer's disease have different causative factors, but they share common themes - such as aggregation of misfolded proteins - and a unifying endpoint, the degenerative loss of neurons, " says Dimitri Krainc, MD, PhD, of the MassGeneral Institute for Neurodegenerative Disease (MGH-MIND), the study's senior author.
A Johns Hopkins-led team of experts in genetics, immunology, epidemiology and allergic disease has embarked on a four-year effort to map the genetic code, or whole genome, of 1, 000 people of African descent, including men and women from Baltimore. Researchers say their initial goal is to find genetic variations underlying asthma and to explain why the disease disproportionately afflicts blacks. As much as 20 percent of African-Americans have asthma, a disease often associated with allergies and marked by difficulty breathing, wheezing, coughing and tightness in the chest. Chronic asthma can lead to serious lung damage, and blacks are three times more likely to be hospitalized or die from the condition than other American adults. Study principal investigator and immunogeneticist Kathleen Barnes, Ph.
Why are certain chromosome regions prone to breakages? The answer is crucial, as this fragility is involved in the development of tumors. A team from the Institut de GĂ nĂ tique et de Biologie MolĂ culaire et Cellulaire (CNRS/Inserm/UniversitĂ de Strasbourg) has partially lifted the veil on the mystery. Laszlo Tora and his colleagues have discovered that breakages in the longest human genes are due to a phenomenon previously considered improbable in mammalian cells: an interference between two key gene processes, DNA transcription (1) and replication (2). Published in the review Molecular Cell of 23 December 2011, this work could give rise to novel anti-tumor strategies in the longer term. Tora and his colleagues began by studying the transcription of very large human genes (over 800 kilobases (3)), known to exhibit DNA breaks called "common fragile sites".
People with diabetes may one day have a less expensive resource for monitoring their blood glucose levels, if research by a group of Missouri University of Science and Technology students becomes reality. Members of the Missouri S&T chapter of iGEM the International Genetically Engineered Machine Foundation recently devised a biological system that uses segments of DNA embedded in bacteria to detect glucose. The students believe their development could lead to a new type of test strip for diabetics. "We designed DNA so that bacteria that have DNA would sense a change in osmolarity due to the presence of glucose, " says Erica Shannon of Wildwood, Mo., a senior in biological sciences at Missouri S&T and president of the campus's iGEM chapter. Osmolarity refers to the concentration of a compound in this case, glucose in a solution.