When it comes to acquiring new equipment, choosing the right instrument for your lab can be daunting―you want to make a worthwhile investment that will go the distance, both in longevity and overall capacity. In a perfect world, the instruments available to you would have been thoroughly tested and reviewed, especially as they compare to one another, making your job that much easier.
In the case of benchtop capillary electrophoresis (CE) instruments, researchers Nastasja Burgardt and Melanie Weissenberger have done just that. Their article, titled “First experiences with the Spectrum Compact CE System”, appeared in the International Journal of Legal Medicine and offered a comprehensive review of the performance of the recently released Spectrum Compact CE System in a forensic genetics laboratory setting.
Researchers looking for new chemistry for Sanger sequencing need look no further than the ProDye™ Terminator Sequencing System, developed by Promega for use in capillary electrophoresis instruments. Sanger sequencing, or dye-terminator sequencing, has been the gold standard of DNA analysis for over 40 years and is a method commonly used in labs around the world. Even as new technologies emerge, Sanger sequencing remains the most cost-effective method for sequencing shorter pieces of DNA.
The global COVID-19 pandemic has changed the entire conference and tradeshow industry. Although plans for many in-person conferences were paused, this month the 32nd International Symposium on Human Identification offered the best of both worlds: an in-person symposium in Orlando, Florida (September 12–16), and a virtual conference where registrants could view the session recordings online. At the symposium, exhibits and poster presentations offered attendees the opportunity to reconnect in person after long absences, while various networking events gave attendees a chance to catch up and socialize.
As usual, workshops were held before and after the main symposium. In a sign of the changing times, Rachel Oefelein and Tarah Nieroda (DNA Labs International) presented a talk on the unique challenges and opportunities associated with virtual courtroom testimony.
The weekend before the symposium was marked by an event of great significance across the world: the 20th anniversary of the September 11, 2001, terrorist attacks on the World Trade Center, the Pentagon, and the attempt on the U.S. Capitol that was thwarted by the brave sacrifice of the passengers and crew on board United Airlines Flight 93. In particular, the DNA forensics community was reminded of how much technology has evolved over the years, in the efforts—still ongoing—to identify the victims of the attacks.
In the summer of 2000, Promega research scientist Allan Tereba was asked to develop an automated protocol for purifying DNA for forensics. His team had recently launched DNA IQ, the first Promega kit for purifying forensic DNA using magnetic beads. This was before the Maxwell® instruments, and before Promega purification chemistries were widely adaptable to high-throughput automation.
“I had my doubts about being able to do that,” Allan says. “When you’re working with STRs, small amounts of contaminant DNA are going to mess up your results. But I went ahead and tried it, and it was a challenge.”
A little over a year later, Allan was in his office when he heard on the radio that a plane had struck the North tower of the World Trade Center in New York City. Shortly after, he heard the announcement that a second plane had hit the South tower.
By that point, Allan and his colleagues had successfully adapted DNA IQ to be used on the deck of a robot. Within days of the attacks, Promega scientists were supporting the New York City Office of Chief Medical Examiner (OCME) and New York State Police in their work to identify human remains that were recovered from Ground Zero.
Thanks to the work of Allan and many other Promega scientists, Promega was prepared to offer unique solutions to urgent needs. In their own words, here are some of those scientists’ reflections.
September 11, 2001 is the day that will live in infamy for my generation. On that beautiful late summer day, I was at my desk working on the Fall issue of Neural Notes magazine when a colleague learned of the first plane hitting the World Trade Center. As the morning wore on, we learned quickly that it wasn’t just one plane, and it wasn’t just the World Trade Center.
Information was sparse. The world wide web was incredibly slow, and social media wasn’t much of a thing—nothing more than a few listservs for the life sciences. Someone managed to find a TV with a rabbit-eared, foil-covered antenna, and we gathered in the cafeteria of Promega headquarters—our shock growing as more footage became available. At Promega, conversation immediately turned to how we could bring our DNA forensic analysis expertise to help and support the authorities with the identification of victims and cataloguing of reference samples.
Just as the internet and social media have evolved into faster and more powerful means of communication—no longer do we rely on TVs with antennas for breaking news—the technology that is used to identify victims of a tragedy from partial remains like bone fragments and teeth has also evolved to be faster and more powerful.
Teeth and Bones: Then and Now
“Bones tell me the story of a person’s life—how old they were, what their gender was, their ancestral background.” Kathy Reichs
Many stories, both fact and fiction, start with a discovery of bones from a burial site or other scene. Bones can be recovered from harsh environments, having been exposed to extreme heat, time, acidic soils, swamps, chemicals, animal activities, water, or fires and explosions. These exposures degrade the sample and make recovering DNA from the cells deep within the bone matrix difficult.
In the fall of 1989, a small group of forensic scientists, law enforcement officials and representatives from Promega Corporation gathered in Madison, Wisconsin, for the very first International Symposium on Human Identification (ISHI). At the time, DNA typing was in its infancy and had not yet been validated as a forensic method. The available technology consisted of two methods: detection of restriction fragment length polymorphisms (RFLPs) and variable number of tandem repeats (VNTRs). Promega had developed products based on both analytical methods, which essentially provide a DNA “fingerprint” or profile for each individual tested.
Among the attendees at that first symposium was Tom Callaghan, then a graduate student. That experience made a significant impact on his career path. Last week, at ISHI 30, he presented a session on rapid DNA testing. Dr. Callaghan currently serves as a Senior Biometric Scientist for the FBI. In 1999, he was instrumental in launching the FBI’s Combined DNA Index System (CODIS) and in 2003, he became the first CODIS Unit Chief.
The rapid advancement of next-generation sequencing technology, also known as massively parallel sequencing (MPS), has revolutionized many areas of applied research. One such area, the analysis of mitochondrial DNA (mtDNA) in forensic applications, has traditionally used another method—Sanger sequencing followed by capillary electrophoresis (CE).
Although MPS can provide a wealth of information, its initial adoption in forensic workflows continues to be slow. However, the barriers to adoption of the technology have been lowered in recent years, as exemplified by the number of abstracts discussing the use of MPS presented at the 29th International Symposium for Human Identification (ISHI 29), held in September 2018. Compared to Sanger sequencing, MPS can provide more data on minute variations in the human genome, particularly for the analysis of mtDNA and single-nucleotide polymorphisms (SNPs). It is especially powerful for analyzing mixture samples or those where the DNA is highly degraded, such as in human remains. Continue reading “Harnessing the Power of Massively Parallel Sequencing in Forensic Analysis”
Today’s post was written by guest blogger Anupama Gopalakrishnan, Global Product Manager for the Genetic Identity group at Promega.
Next-generation sequencing (NGS), or massively parallel sequencing (MPS), is a powerful tool for genomic research. This high-throughput technology is fast and accessible—you can acquire a robust data set from a single run. While NGS systems are widely used in evolutionary biology and genetics, there is a window of opportunity for adoption of this technology in the forensic sciences.
Currently, the gold standard is capillary electrophoresis (CE)-based technologies to analyze short tandem repeats (STR). These systems continue to evolve with increasing sensitivity, robustness and inhibitor tolerance by the introduction of probabilistic genotyping in data analysis—all with a combined goal of extracting maximum identity information from low quantity challenging samples. However, obtaining profiles from these samples and the interpretation of mixture samples continue to pose challenges.
MPS systems enable simultaneous analysis of forensically relevant genetic markers to improve efficiency, capacity and resolution—with the ability to generate results on nearly 10-fold more genetic loci than the current technology. What samples would truly benefit from MPS? Mixture samples, undoubtedly. The benefit of MPS is also exemplified in cases where the samples are highly degraded or the only samples available are teeth, bones and hairs without a follicle. By adding a sequencing component to the allele length component of CE technology, MPS resolves the current greatest challenges in forensic DNA analysis—namely identifying allele sharing between contributors and PCR artifacts, such as stutter. Additionally, single nucleotide polymorphisms in flanking sequence of the repeat sequence can identify additional alleles contributing to discrimination power. For example, sequencing of Y chromosome loci can help distinguish between mixed male samples from the same paternal lineage and therefore, provide valuable information in decoding mixtures that contain more than one male contributor. Also, since MPS technology is not limited by real-estate, all primers in a MPS system can target small loci maximizing the probability of obtaining a usable profile from degraded DNA typical of challenging samples.
The backlog of sexual assault kit samples in crime laboratories across the nation is a topic that hit the spotlight when a group of journalists uncovered the issue in an open records search of crime lab records in 2015. Reasons for the backlog include lack of staff, lack of funding, and simply, lack of time or a decision not to prosecute the case. Processing samples can be a labor-intensive process.
We recently interviewed Lynndsey R. Simon, Forensic Scientist II and Alternate CODIS Administrator from the Columbus Police Forensic Services Center to discuss some recent changes in sample processing in their laboratory that are helping to alleviate some of the backlog. She will be presenting a talk at the upcoming International Symposium on Human Identification (ISHI) in September.
The Columbus Police Forensic Services Center is a smaller forensic laboratory and according to Simon, one of the biggest challenges they face is strained resources. The DNA extraction and processing kits that forensic laboratories use are very expensive, and the number of DNA samples that laboratories are getting for DNA analysis are increasing. With limited resources and funding, maximizing efficiency and finding the best solutions for the laboratory becomes critical. Continue reading “Forensic Scientists Improve Sexual Assault Kit Turnaround Time with Y-Screening”
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