Discovery could help bring down price of DNA sequencing

Discovery could help bring down price of DNA sequencing June 29, 2007 In May, Nobel Laureate James D. Watson, the scientist who co-discovered the structure of DNA, became the first person to receive his own complete personal genome - all three billion base pairs of his DNA code sequenced. The cost was $1 million, and the process took two months. A million dollars for a map of all your genes is way out of reach for most people. The National Institutes of Health would like to bring it down to $1,000 by the year 2014, but plenty of technological hurdles remain before you’ll be able to secure your genetic blueprint for this more affordable price. One promising method for speeding up DNA sequencing, and thus reducing its cost, is nanopore sequencing, where DNA moves through a tiny hole, much like thread going through a needle. The technique can detect individual DNA molecules, but the DNA gallops through so fast that it is impossible to read the individual letters, or bases, and determine the sequence. (The four letters of the genomic alphabet are A, T, G and C, each representing one of the base nucleotides that make up DNA.) Using a theory based on classical hydrodynamics, a Northwestern University researcher now has explained the nature of the resistive force that determines the speed of the DNA as it moves through the nanopore, which is just five to 10 nanometers wide. (One nanometer is a billionth of a meter.) This understanding could help scientists figure out how to slow the DNA down enough to make it readable and usable - for medical and biotechnology applications, in particular. Sandip Ghosal, associate professor of mechanical engineering in Northwestern’s McCormick School of Engineering and Applied Science, is the first to apply classical hydrodynamics to the interaction of DNA with a nanopore. The findings, an important step toward achieving single-base resolution in nanopore sequencing, were published in the June 8 issue of the journal Physical Review Letters (PRL). “DNA is pulled through the nanopore’s channel by an electric force, but there also is a resistive force,” said Ghosal, sole author of the PRL paper. “My idea was that the resistance was coming from fluid friction, which could explain the speed measurements taken in experimental studies.” In Ghosal’s explanation, the DNA pulls some of the fluid surrounding the molecule through the channel with it. The lubrication forces arising in this fluid layer create the resistance that opposes the electrical pulling force. Ghosal’s calculations in the PRL paper show that his theoretical model is consistent with experimental results and explains the DNA’s speed. “Understanding the mechanics of DNA translocation will allow scientists to make alterations, to figure out how to apply more friction,” said Ghosal, who has proposed using a coating on the channel walls to slow down the flow of the DNA. ......... ZenMaster

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Cloned pigs help scientists towards a breakthrough in Alzheimer's

Cloned pigs help scientists towards a breakthrough in Alzheimer's June 29, 2009 The first pigs containing genes responsible for Alzheimer's disease will be born in Denmark in August. This event is a landmark achivement in the effort towards finding a cure for the disease. Scientists from the universities of Copenhagen and Århus, Denmark are once again at the cutting edge of biotechnology. This time with cloned pigs that have been genetically modified so that they may function as animal models for the notorious Alzheimer’s disease. "In the light of the intense focus on medical research at the University of Copenhagen and the continuous expansion of the pharmaceutical industry in Denmark, the ability to produce transgenic pig models for human diseases is a major prerequisite for future progress in this area," says Professor Ingrid Brück Bøgh from the Department of Large Animal Sciences, University of Copenhagen. "The upcoming birth of these transgenic pig models constitutes a fantastic success for us. It is also a demonstration of the excellent cross-disciplinary collaboration between the experts at both universities," she continues. "We now have evidence that our system is very well suited for the task of making disease models for human medicine," says Professor Gábor Vajta from the Department of Genetics and Biotechnology, Faculty of Agricultural Sciences, University of Aarhus. Associate Professor Arne Lund Jorgensen, Institute of Human Genetics, Aarhus University and his group have made the gene construct with the putative Alzheimer gene and inserted into the somatic cells. These somatic cells were used for the nuclear transfer experiments performed at the Faculty of Agricultural Sciences, Aarhus University. ......... ZenMaster

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New Regulations Needed For Xenotransplantations

New Regulations Needed For Patients Receiving Animal Tissue Donation June 29, 2007 A new article in the Journal of Law, Medicine and Ethics calls for a change in the regulations surrounding xenotransplantation, the transplanting of animal cells, tissues or organs into humans. Although few xenotransplantation procedures have been done to this time, there appears to be a lack of awareness among potential xenotransplant patients about the risk of the procedures, and the required lifetime of infectious disease monitoring that come with it. ......... ZenMaster

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