A smudge of blood at a crime scene may provide enough evidence for investigators to determine the age of criminals or victims, thanks to a new procedure that analyzes the age-related loss of specific DNA molecules in immune cells.
Blood droplets

The approach is more reliable than other genetic analyses and does not involve the destruction of evidence, forensic molecular biologist linkurl:Manfred Kayser,;http://www.erasmusmc.nl/fmb/?lang=en whose study was published online today (22 November) in Current Biology, told The Scientist.T cells must develop different types of surface receptors so that they can recognize and respond to a wide range of foreign pathogens. Inside the thymus, gene segments encoding T-cell receptors rearrange to produce distinct receptors, and as a byproduct, some deleted DNA sequences form circular fragments inside the cell called signal joint TCR excision circles (sjTRECs). As the function of the thymus declines with age, so does the number of sjTRECs. Taking...
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