In the late 1800s, Victorian England was mesmerized and horrified by a series of brutal killings in the crowded and impoverished Whitechapel district. The serial killer, who became known as “Jack the Ripper”, had murdered and mutilated at least five women, many of whom worked as prostitutes in the slums around London. None of these murders were ever solved, and Jack the Ripper was never identified, although investigators interviewed more than 2,000 people and named more than 100 suspects. Now, 126 years after the murders, a British author, who coincidentally has just published a book on the subject, is claiming that DNA analysis has revealed the identity of the notorious killer. DNA is often thought to be the “gold standard” of human identification techniques, so why is there so much skepticism surrounding this identification?
Continue reading “DNA Reveals the Identity of Jack the Ripper?”
Recently, researchers of the SIGMA Type 2 Diabetes Consortium published a paper in Nature identifying a new locus associated with a higher risk of type 2 diabetes (1). Considering the increasing prevalence of this metabolic disease in today’s sugar-filled world, any discovery that helps us understand diabetes is exciting news. However, the most interesting discovery published in this paper might not be this new gene variant but rather the origin of this variant in modern human populations: Neandertals.
At the recent International Symposium on Human Identification, Kevin Davies, the keynote speaker and author of The $1,000 Genome, entertained attendees with a history of human genome sequencing efforts and discussed ways in which the resulting information has infiltrated our everyday lives. Obviously, there is enough material on the subject to fill a book, but I will describe just a few of the high points of his talk here.
As scientists, we’ve all have those moments when we are asked to explain to a nonscientist—maybe Mom or Grandpa—what it is we do all day in the lab. Or maybe someone asks us a seemingly innocent question such as “How can DNA be used to identify someone?” Do you try to teach them about polymorphic DNA sequences, population genetics, PCR, capillary electrophoresis, the necessary statistical calculations and all of the other factors involved? Even if your audience members are patient enough for that, will they understand, or will their eyes glaze over after the first 10 minutes? If you’re like me, you give your inquisitor the high-level, 30,000-foot overview of the topic and hope that that is enough to satisfy their curiosity. Answer the question, but don’t get bogged down in too much detail unless your audience really seems genuinely interested in delving further.
That’s all fine and good if you can get away with that approach, but there are situations where the high-level overview won’t suffice. Continue reading “Your Day in Court: Becoming an Effective Expert Witness”
If you enter any molecular lab asking to borrow some Proteinase K, lab members are likely to answer: “I know we have it. Let me see where it is”. Sometimes the enzyme will be found to have expired. The lab may also have struggled with power outages or freezer malfunctions in the past. But the lab still decides to keep the enzyme. One may rightly ask – why do labs hang on to Proteinase K even when it has been stored under sub-standard conditions? Continue reading “ProK: An Old ‘Pro’ That is Still In The Game”
For sixty years now, scientists have studied the role of DNA as a vehicle for the storage and transmission of genetic information from generation to generation. We have marveled at the capacity of DNA to store all the information required to describe a human being using only a 4-letter code, and to pack that information into a space the size of the nucleus of a single cell. A letter published last week in Nature exploits this phenomenal storage capacity of DNA to archive a quite different kind of information. Forget CDs, hard drives and chips, the sum of human knowledge can now be stored in synthetic DNA strands. The Nature letter, authored by scientists from the European Bioinformatics Institute in Cambridge, UK, and Agilent Technologies in California, describes a proof-of-concept experiment where synthetic DNA was used to encode Shakespeare’s Sonnets, Martin Luther King’s “I Have a Dream” speech, a picture of the Bioinformatics Institute, and the original Crick and Watson paper on the double-helical nature of DNA. Continue reading “Sonnets in DNA”
There are at least two tail stories associated with big scientific discoveries. One is Darwin’s story about the tail loss during human evolution process. The other story is associated with discovery of benzene ring structure. In his creative dream Kekule saw the snake (the linear carbon chain) eating its own tail. Even better representation of benzene structure is the comic image of six monkeys holding each other hands and tails. Nowadays, the most popular scientific story in the field of epigenetics is the story of histones and their tails. This time instead of monkey or snake, an elephant is the animal whose characteristics allegorically represent epigenetics.
We all know how the histone octamer wrapped with DNA represents a nucleosome – the first unit of chromatin formation. Histones, which are basic due to numerous arginines and lysines, easily attract negatively charged DNA and in that way facilitate formation of nucleosome. The nature of two materials is important but not sufficient for such complex biological function like efficient packaging of DNA and regulation of gene expression. For that reason both the DNA and histones are decorated by numerous chemical groups.
Post-translational modifications (PTMs) of histones and histone variants themselves can cause alternation of net charge, changes histone dynamics and interaction with other chromatin proteins. The extreme complexity of interactions that can be achieved by histone modifications inspired Jenuwein and Allis to launch an idea of “histone or epigenetic code”. Core histones consist of a N- terminal tail, the globular portion and a C terminus. PMTs were discovered first on the N-terminal tail of core histones. However, the logical question was: Are only the tails decorated or are there more?” Continue reading “Decorating Histones and Their Tails”
John Wayne Gacy was a notorious serial killer who sexually assaulted and murdered 33 boys and young men in the 1970s in Chicago, Illinois. The killing spree stopped only when he was arrested in 1978 after the parents of his last victim contacted police with critical information that implicated Gacy in the boy’s disappearance. He was tried, convicted and in 1994 executed for his crimes. Of the 33 victims that police found buried in and around his home, only 25 could be identified, leaving eight victims nameless and eight families to wonder if their missing loved one died at the hands of this evil man. When all available means of identification were exhausted, these eight sets of remains were buried but not forgotten.
In 2011, these remains were exhumed and the victim’s DNA analyzed to try to provide clues as to their identity. Continue reading “Identifying the Victims of John Wayne Gacy”
A good scientist always keeps an open mind, even when faced with an observation or hypothesis that seems, shall we say, far-fetched. This can be difficult at times, especially when there is little supporting scientific evidence. Maybe that’s why the field of cryptozoology doesn’t get much respect in the scientific community. Cryptozoology is literally translated as “the study of hidden animals” and encompasses efforts to find and identify animals whose existence is unproven, including the Loch Ness Monster, Chupacabra and Bigfoot. These “cryptids”, as they are called, often appear in folklore or legends, but there is little definitive physical evidence to support their existence. The evidence includes unsubstantiated eyewitness accounts, grainy photographs, mysterious tracks or unidentified hair. Despite this, some open-minded scientists at the University of Oxford and Musée de Zoologie in Lausanne, Switzerland, are teaming up to examine biological evidence that cryptozoologists claim support Bigfoot’s existence. Their project, named the Oxford-Lausanne Collateral Hominid Project, involves DNA testing and may provide some answers.
Continue reading “Will DNA Provide an Answer about Bigfoot’s Existence?”
Identical twins are derived from the same fertilized ovum and, therefore, should be…well… identical, right? They look the same and often dress the same, especially as children, and many people often have a hard time distinguishing one twin from the other. They are indistinguishable by genetic testing.
However, identical twins are not always identical, as the authors of a recent letter to the editor of Forensic Science International Genetics point out (1). Continue reading “How Identical are Identical Twins?”