Daily Archives: September 12, 2012

MADISON, Wis.--(BUSINESS WIRE)--

Forensic DNA professionals confront many challenges: cold case investigations, DNA backlogs and new applications like rapid DNA and kinship DNA testing. The 23rd International Symposium on Human Identification (ISHI) presents forensic professionals with an opportunity to learn about these and other developing forensic DNA technologies alongside fellow scientists, law enforcement professionals and forensic experts. This years ISHI will be held October 15-18 in Nashville, Tennessee at the Gaylord Opryland Resort.

As the largest conference on DNA analysis for human identification, the symposium attracts more than 800 DNA analysts and forensic scientists from around the world, providing these professionals an opportunity to explore and debate the latest research, technologies and ethical issues in the industry today. This years presenters and topics include:

Author and Educator Douglas Starr

Co-director of Boston Universitys graduate program in Science and Medical Journalism and author of Gold Dagger award-winning book The Little Killer of Shepherds: A True Crime Story and the Birth of Forensic Science, Starr is this years keynote speaker. In his latest book, Starr tells the story of forensic sciences 19th century pioneers and the notorious serial killer they caught and convicted using their new scientific techniques. Winner of the Gold Dagger award in the U.K. and a finalist for the Edgar Allen Poe award in the U.S., the book received laudatory reviews, including an Editors Choice listing in the New York Times Book Review and a place on the True Crime Bestseller lists of the Wall Street Journal and Library Journal.

SNA International Founder Amanda Sozer

SNA International lends expertise to forensic labs and mass fatality identification projects. Founder and President Amanda Sozer, who received recognition for her outstanding efforts during 9/11 and Hurricane Katrina, will be leading a workshop on forensic science and human rights at ISHI. The workshop will include speakers who have worked on human rights projects as well as a presentation on the AAAS Guidelines for Scientists and Human Rights Organizations, developed by a group of collaborating scientists and representatives of human right organizations. The guidelines are designed to be helpful to those establishing science and human rights partnerships and to facilitate and promote cooperation between scientists and human rights organizations seeking scientific expertise.

Sequencing the Black Death Genome: Hendrik Poinar

Hendrik Poinar and his colleagues at McMaster University in Hamilton, Ontario, Canada developed a technique to find and sequence the Black Death genome using the skeletal remains of its victims. The possibility of environmental contamination was high. To address this, Poinar and his team extracted the DNA using a molecular probe made from a modern strain of DNA, testing this new technique on approximately 100 samples of teeth and bone excavated from a London plague pit. The result was a strain of Y. pestis unlike any known today: the Black Death. Poinar will share details of this process during his talk at ISHI.

Workshops: DNA Backlog Reduction, Cold Case Investigative Techniques

Read more:

2012 International Symposium on Human Identification Features Emerging and Best Practice Forensic DNA Techniques ...

There was an extremely strong chance DNA found inside the underpants of a five-year-old girl came from the man accused of abusing her, a court has heard.

But the ACT Supreme Court has been told tests for saliva turned up nothing, despite the girls allegation her step-grandfather licked her vagina.

And the court has heard tests werent carried out on other items of clothing and bedding because they were likely to be covered in his DNA and have no probative value.

The underpants were also placed in the same bag as another item of clothing, prompting the defence to suggest the DNA might have transferred from one to the other.

Advertisement

The 61-year-old man, who cannot be named, is on trial in front of Justice Richard Refshauge accused of two counts of having sexual intercourse with a child.

He has pleaded not guilty, and also denies two alternative charges of committing acts of indecency on the girl.

It is alleged he licked the girls vagina twice when he was babysitting her in April 2009.

The allegations came to light after the girls mother picked her up, when the girl asked her mother if she could tell her the secret she shared with poppy.

The accused man entered the witness box this afternoon and denied any wrongdoing, describing his shock when police confronted him with the allegations.

Link:

Court hears DNA findings in child sex case

ScienceDaily (Sep. 11, 2012) DNA is constantly being damaged by environmental agents such as ultraviolet light or certain compounds present in cigarette smoke. Cells unceasingly implement repair mechanisms for this DNA, which are of redoubtable efficacy. A team from Institut Jacques Monod (CNRS/Universit Paris Diderot), in collaboration with scientists from the Universities of Bristol in the UK and Rockefeller in the USA, has for the first time managed to follow real-time the initial steps in one of these hitherto little known DNA repair systems. Working in a bacterial model, and thanks to an innovative technique applied to a single molecule of DNA, the scientists were able to understand how several actors interact to ensure the reliable repair of DNA.

Published in Nature on 9 September 2012, their work aims to better understand the onset of cancers and how they become resistant to chemotherapies.

Ultraviolet light, tobacco smoke or even the benzopyrenes contained in over-cooked meat can cause changes to the DNA in our cells, which may lead to the onset of cancers. These environmental agents deteriorate the actual structure of the DNA, notably causing so-called "bulky" lesions (like the formation of chemical bonds between DNA bases). In order to identify and repair this type of damage, the cell can call on several systems, such as transcription-coupled repair (TCR), whose complex mechanism of action still remains poorly understood today. Abnormalities affecting this TCR mechanism -- which permits permanent monitoring of the genome -- are the cause of some hereditary diseases such as Xeroderma pigmentosum, sufferers from which are hypersensitive to the Sun's ultraviolet rays and are commonly referred to as "children of the night."

For the first time, a team from Institut Jacques Monod (CNRS/Universit Paris Diderot), in collaboration with scientists at the Universities of Bristol in the UK and Rockefeller in the USA, has succeeded in observing the initial stages of TCR repair mechanisms in a bacterial model. To achieve this, they employed a novel technique for the nanomanipulation of individual molecules[1] which allowed them to detect and follow real-time the interactions between the molecules in play in a single damaged DNA molecule. They elucidated the interactions between different actors during the first steps of this TCR process. A first protein, RNA polymerase[2], usually crosses DNA without mishap, but is stalled when it meets a bulky lesion (like a train blocked on its rails by a landslide). A second protein, Mfd, binds to the stalled RNA polymerase and removes it from the damaged "rail" so that it can then replace it with the other proteins necessary to repair the damage. Measurements of the reaction speeds enabled the observation that Mfd acts particularly slowly on RNA polymerase, pushing it out of the way in about twenty seconds. Furthermore, Mfd does indeed displace stalled RNA polymerase, but then remains associated with the DNA for a longer period (of about five minutes), allowing it to coordinate the arrival of other repair proteins at the damaged site.

Although the scientists were able to explain how this system can achieve almost 100% reliability, a even clearer understanding of these repair processes is still essential in order to determine how cancers appear and subsequently may become resistant to chemotherapies.

Notes:

[1] During these nanomanipulation experiments, damaged DNA was grafted onto a glass surface on one side and a magnetic microbead on the other. The bead surface enabled the perpendicular extension of the DNA and measurement of this end-to-end extension using videomicroscopy. The binding to DNA of different proteins, and their action, is identifiable from the modification the protein generates in the structure or conformation of the DNA. This technique enables an extremely detailed structural and kinetic analysis of in vitro biochemical reactions.

[2] RNA polymerase is responsible for the reading of DNA by a gene and its rewriting in an RNA form, a process known as transcription. It has been shown that RNA polymerase does not only transcribe genes, but also the DNA between genes (until recently referred to as "junk" DNA), allowing, for example, polymerase RNA to perform its quality control by TCR on the entire genome of an organism.

Share this story on Facebook, Twitter, and Google:

Other social bookmarking and sharing tools:

Continue reading here:

Real-time observation of single DNA molecule repair