Monthly Archives: September 2013

Hunting for Dinosaur DNA
From the BBC Horizon documentary Dinosaurs: The Hunt for Life, how Dr Mary Schweitzer found organic matter in ancient fossils.

By: lesterfontayne

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Hunting for Dinosaur DNA - Video

LEBANON, Ind. - A forensics expert says blood on the clothing of a former state trooper accused of killing his wife, son and daughter 13 years ago could not have gotten there when the trooper found the boy's body, as the trooper insists.

Sgt. Dean Marks told jurors Thursday that DNA analysis revealed that eight blood dots on David Camm's T-shirt belong to his 5-year-old daughter Jill, not his 7-year-old son Bradley. Camm's lawyers have maintained throughout Camm's two previous murder trials that the blood got onto his shirt when Camm attempted CPR on his son.

Camm has been convicted twice of killing his wife, Kimberly and their two children, whose bodies were found in the family's garage. But both convictions were overturned on appeal. Because of the heavy publicity surrounding the case in and around Georgetown, the southern Indiana suburb of Louisville where the family lived, Camm's third trial was about 125 miles north to Lebanon.

Marks told the jury he studied more than 140 photographs of the blood patterns and cutout sections from the shirt worn by Camm. Where the spatters of blood came from and how they got there are key to prosecutors' case.

"This is consistent with gunshot spatter," Marks testified.

Defense attorneys argue the initial blood tests were made by an inexperienced scientist who had never been trained in blood spatter analysis and never before worked at a crime scene. They also say police rushed to judgment and overlooked key evidence.

Jurors on Thursday also watched video of a two-hour interview in which Camm tells his state police colleagues that he had nothing to do with killing his family.

"What's going to happen, you guys are going to get so focused on me that the guy who did this is going to walk away," Camm said.

Under questioning by defense attorney Stacy Uliana, Detective Robert Neal acknowledged that police lied when they told Camm that investigators had found blood on his jacket and other pieces of evidence against him.

He said such lies are considered an acceptable strategy to "get at the truth" when interrogating a prime suspect.

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DNA expert disputes source of blood

Sep. 6, 2013 Graphene is a sheet of carbon atoms arrayed in a honeycomb pattern, just a single atom thick. It could be a better semiconductor than silicon -- if we could fashion it into ribbons 20 to 50 atoms wide. Could DNA help?

DNA is the blueprint for life. Could it also become the template for making a new generation of computer chips based not on silicon, but on an experimental material known as graphene?

That's the theory behind a process that Stanford chemical engineering professor Zhenan Bao reveals in Nature Communications.

Bao and her co-authors, former post-doctoral fellows Anatoliy Sokolov and Fung Ling Yap, hope to solve a problem clouding the future of electronics: consumers expect silicon chips to continue getting smaller, faster and cheaper, but engineers fear that this virtuous cycle could grind to a halt.

Why has to do with how silicon chips work.

Everything starts with the notion of the semiconductor, a type of material that can be induced to either conduct or stop the flow of electricity. Silicon has long been the most popular semiconductor material used to make chips.

The basic working unit on a chip is the transistor. Transistors are tiny gates that switch electricity on or off, creating the zeroes and ones that run software.

To build more powerful chips, designers have done two things at the same time: they've shrunk transistors in size and also swung those gates open and shut faster and faster.

The net result of these actions has been to concentrate more electricity in a diminishing space. So far that has produced small, faster, cheaper chips. But at a certain point, heat and other forms of interference could disrupt the inner workings of silicon chips.

"We need a material that will let us build smaller transistors that operate faster using less power," Bao said.

Originally posted here:
Scientists use DNA to assemble a transistor from graphene

Public release date: 6-Sep-2013 [ | E-mail | Share ]

Contact: Steven Benowitz steven.benowitz@nih.gov 301-451-8325 NIH/National Human Genome Research Institute

The use of nanopore technology aimed at more accurate and efficient DNA sequencing is the main focus of grants awarded by the National Institutes of Health. The grants nearly $17 million to eight research teams are the latest awarded through the National Human Genome Research Institute (NHGRI)'s Advanced DNA Sequencing Technology program, which was launched in 2004. NHGRI is part of NIH.

"Nanopore technology shows great promise, but it is still a new area of science. We have much to learn about how nanopores can work effectively as a DNA sequencing technology, which is why five of the program's eight grants are exploring this approach," said Jeffery A. Schloss, Ph.D., program director for NHGRI's Advanced DNA Sequencing Technology program and director of the Division of Genome Sciences.

Nanopore-based DNA sequencing involves threading single DNA strands through tiny pores. Individual base pairs the chemical letters of DNA are then read one at a time as they pass through the nanopore. The bases are identified by measuring the difference in their effect on current flowing through the pore. For perspective, a human hair is 100,000 nanometers in diameter; a strand of DNA is only 2 nanometers in diameter. Nanopores used in DNA sequencing are 1 to 2 nanometers in diameter.

This technology offers many potential advantages over current DNA sequencing methods, said Dr. Schloss. Such advantages include real-time sequencing of single DNA molecules at low cost and the ability for the same molecule to be reassessed over and over again. Current systems involve isolating DNA and chemically labeling and copying it. DNA has to be broken up, and small segments are sequenced many times. Only the first step of isolating the DNA would be necessary with nanopore technology.

Innovation is crucial in these as well as the other (non-nanopore) studies being funded. For example, one research team eventually hopes to use light to sequence DNA on a cell phone camera chip for under $100.

The new grants are awarded to:

Dr. Aksimentiev and his colleagues plan to use nanopores as sensors. The researchers are studying the effects of combining synthetic nanopores with a light-based technique to control the flow of DNA molecules through the pores. They will use a type of spectroscopy to read the chemical sequence of the DNA.

Dr. Edwards and his colleagues plan to develop innovative molecular biology tools to improve whole-genome sequencing, which entails reading a person's entire genetic blueprint. The researchers hope that better methods of preparing the DNA molecules for sequencing will help scientists identify and link genetic variants to disease and, ultimately, lead to new treatments.

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New NIH awards focus on nanopore technology for DNA sequencing