Those of us lucky enough to attend the 26th International Symposium on Human Identification (ISHI) can agree that the meeting was a resounding success once again this year—plenty of outstanding workshops, presentations and posters, great networking and learning opportunities and, of course, fun with new and existing friends and colleagues.
Now that we’ve all had a chance to recover from all of the excitement, let’s recap some of the meeting highlights.
Scientists have known for some time that fetal DNA can be detected in the maternal bloodstream during pregnancy (1). Up to 10% of circulating cell-free-DNA (ccfDNA) can be attributed to the fetus. Fetal ccfDNA is released from the placenta, mainly through apoptosis, and enters the maternal bloodstream, where it can be easily collected and detected by PCR amplification. This method of collection has a much lower risk of miscarriage compared to more invasive collection methods such as amniocentesis and chorionic villus sampling.
Amplification of fetal ccfDNA enables a number of prenatal genetic testing such as gender determination and detection of fetal aneuploidy and other mutations. Testing of ccfDNA also allows identification of fetuses with a higher risks of hemolytic disease of the newborn (erythroblastosis fetalis) due to expression of the Rh factor in an Rh– negative mother, who can develop antibodies against the Rh factor and mount an immune response against fetal red blood cells. Finally, ccfDNA allows prenatal paternity determination (2). However, these tests have limitations.
Engraving of the human heart by T. Milton, 1814. Image courtesy of Wikimedia Commons.
Every year, nearly 8 million people die from sudden cardiac death
, which is defined as the unexpected death of a seemingly healthy person due to malfunctions in the heart’s electrical system and loss of cardiac function. Although sudden cardiac death (SCD) is usually associated with mature adults, SCD claims thousands of young lives every year. In most cases, the cause of death can be determined by autopsy or toxicological analysis, but up to 30% of these premature deaths have no apparent cause, leaving medical examiners and family members of the young victims to wonder what happened.
In cases where traditional pathological examinations cannot provide insight into causation, medical examiners are increasingly turning to molecular autopsies to determine if there is an underlying genetic factor that contributed to a person’s death.
A guanine tetrad (left) and G-quadruplex (right). Image courtesy of Wikimedia Commons.
Proto-oncogenes are genes that organisms rely on for normal growth and development but, when mutated or dysregulated, can cause cells to grow uncontrollably, resulting in cancer and metastasis. In some cases, a single DNA mutation is sufficient for cancer to develop. Why then, do so many proto-oncogene promoters contain strings of guanine residues, which are extremely vulnerable to DNA damage from factors such as oxidative stress and hyperinflammation, to control transcription levels? From an evolutionary viewpoint, this is a contradiction: DNA sequences that are the most vulnerable to damage and mutation are key to regulating one of the cell’s most dangerous classes of genes. This seems to be a recipe for genomic instability and disease. Fortunately, evolution has provided a very clever solution to this potential problem.
By Fredy Peccerelli
Guatemala’s method of uncovering human rights violations can help other post-conflict areas, says Fredy Peccerelli.
During Guatemala’s internal armed conflict (1960–1996) almost 200,000 people are thought to have been killed or ‘disappeared’ at the hands of repressive and violent regimes. Those lives matter. Their families’ demands are clear: they want to know what happened to their loved ones and they want their remains returned. They need truth and justice.
Using forensic sciences, the Forensic Anthropology Foundation of Guatemala (FAFG) is assisting families by returning their loved ones’ remains, promoting justice, and setting the historical record straight.
Imagine being convicted of a crime for which you are not guilty—not some minor crime, but one of the most heinous crimes imaginable: the rape and murder of a young girl. Would you feel shock and anger at the injustice? Disappointment in the legal system that could make such a horrible error? Sadness and depression at the thought of spending time imprisoned for a crime that someone else committed? Probably all of those emotions and more. At your sentencing hearing, the situation gets worse; you are sentenced to death. Now, this horrible crime will prematurely claim the life of two innocents: the young girl and you.
This is the situation that Kirk Bloodsworth faced in 1985: a death sentence for the rape and murder of 9-year-old Dawn Hamilton. Although Bloodsworth didn’t know it at the time, DNA testing would eventually prove his innocence and save his life.
DNA-based evidence has a long history of admissibility in legal proceedings stretching back to 1985 when Sir Alec Jeffreys first used DNA testing to resolve an immigration dispute in the United Kingdom. In 1987, DNA made more court appearances in parallel legal cases to convict serial rapist and murderer Colin Pitchfork in the UK and rapist Tommy Lee Andrews in the United States. Since these cases, the admissibility of DNA evidence in US courts has been challenged and upheld numerous times (United States v. Jakobetz and Andrews v. Florida), and DNA evidence has become the gold standard in many court cases. So why are scientists being asked once again to debate the admissibility of DNA evidence, specifically high sensitivity DNA, in the courtroom?
Curling up with a good book is one of life’s greatest pleasures, whether you’re reading on a tropical beach while on vacation or nestled into your favorite chair at home. As your eyes skim over the words, your mind conjures up images of the events unfolding on the page. Books can take us to fantastic places, real and imaginary, that we will never visit in our lifetime. And while there is some pleasure to be gained from nonfictional books, my favorite books all seem to fall in the realm of fiction. I am not alone. The science fiction and fantasy genre of literature continues to be one of the most popular. Why do so many readers find these types of books so enticing and engaging?
It all comes down to science, specifically neuroscience.
Every day we are bombarded by potential contagions: whether a physical ailment such as measles or influenza or something as seemingly harmless as a yawn or popular Internet meme. For better or worse, emotions can be contagious too, passed on from one person to another through verbal and nonverbal cues, with or without the awareness that we are being affected by another person’s emotional state. In many cases, the only route for such transmission is observation. For example, who hasn’t felt better after watching an uplifting film or cried while watching a sad movie. In the lab, scientists have determined that levels of the stress hormone cortisol increased in individuals undergoing a stress test but also in passive observers who watch the stress test through a one-way mirror or on a television screen. Often, the magnitude of the observer’s response is affected by how well he knows or can relate to the person.
As reported in a recent PLOS ONE article(1), we now know that even a physiological response to cold temperatures is readily transmissible from one person to another, although many of us who live in northern climates probably knew this long before any scientific study: Watching children playing in the snow or someone shoveling snow can often send a chill through us even though we are watching from a heated building. However, a group of scientists in the UK and Germany was not satisfied with anecdotal evidence of temperature contagion, as they named this phenomenon. They did the experiment and generated the data.
miR-133 microRNA (green) and myogenin mRNA (red) in differentiating C2C12 cells. Image by Ryan Jeffs, courtesy of Wikimedia Commons.
Some of us scientists who have been around for a while still think about RNA molecules falling into three categories: messenger RNA (mRNA), ribosomal RNA (rRNA) and transfer RNA (tRNA). However, within the past few decades I have had to revise my outdated RNA classification scheme as scientists discover exciting new classes of RNAs that do some fairly amazing things. For example, in the early 1980s, Thomas Cech discovered ribozymes, RNAs that have catalytic functions (1), and in the early 1990s, researchers began to take interest in short noncoding RNAs that act as a genetic regulators, the first of which was discovered in C. elegans (2). RNA is no longer simply a biological middleman between DNA and protein. These ephemeral nucleic acid molecules play a much bigger role of cellular physiology and gene regulation than we had previously ascribed to RNA.