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Archive - Nov 19, 2009

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Corn Genome Sequence Is Detailed

A four-year, multi-institutional effort culminated today in publication of a landmark series of papers in the journal Science, revealing in unprecedented detail the DNA sequence of maize (Zea mays). Maize, or corn, as it is commonly called by North American consumers, is one of the world's most important plants and the most valuable agricultural crop grown in the United States, representing $47 billion in annual value. The sequence spans 2.3 billion DNA base-pairs and contains some 32,500 genes, or about one-third more than the human genome, according to the team that assembled it over the last four years. This version of the maize genome--taken from a variant called B73--is important, in part, because it is regarded by the scientific and agricultural communities as a "reference" version. It represents a significant filling-in of gaps in a draft maize sequence announced a year and a half ago, but more importantly, comes with what amounts to a detailed reference manual, a set of comprehensive annotations. "What's important about the maize project," said Dr. W. Richard McCombie, a Cold Spring Harbor Laboratory (CSHL) professor, a co-principal investigator on the maize genome project, and a pioneer in genome sequencing efforts, "is that it provides a reference DNA sequence for the most important agricultural crop in the U.S., making it much easier for people to look at the many variants of different strains or 'accessions' of maize." New sequencing technologies, just now becoming commercially viable, will now be used to "analyze other maize strains by comparing them to this one--albeit at dramatically lower costs and accelerated speeds," Dr. McCombie noted. Another of the co-project leaders from CSHL, Professor Robert Martienssen, put the maize sequencing project into historical perspective.

Stanford Mouse Study Suggests Possible Help for Down Syndrome

New findings from researchers at the Stanford University School of Medicine and Lucile Packard Children's Hospital, and colleagues, shed light on the neural basis of memory defects in Down syndrome and suggest a new strategy for treating the defects with medication. The study, which was conducted in mice, is the first to show that boosting norepinephrine signaling in the brains of mice, which have been genetically engineered to mimic Down syndrome, improves their cognition. Norepinephrine is a neurotransmitter that nerve cells use to communicate. The scientists said that their findings raise the possibility that restoring norepinephrine-mediated neurotransmission could reverse cognitive dysfunction in Down syndrome. "If you intervene early enough, you will be able to help kids with Down syndrome to collect and modulate information," said Dr. Ahmad Salehi, the first author of the study. "Theoretically, that could lead to an improvement in cognitive functions in these kids." The results give "a ray of hope and optimism for the Down syndrome community for the future," said Dr. Melanie Manning, director of the Center for Down Syndrome at Lucile Packard Children's Hospital. Dr. Manning was not a part of the research team. "It's very exciting," she said. "We still have a long way to go, but these are very interesting results." This report was featured as the cover story of the November 18 issue of Science Translational Medicine. [Press release] [Science Translational Medicine abstract]