Q&A: Mitchell Holland

The professor's DNA sequencing research can speed up crime scene investigations.

Mitchell Holland

Q: Your lab is advancing techniques to sequence DNA. What does that mean?
Holland
: We’re testing new methods of sequencing DNA from hair samples. Hairs without roots are commonly recovered from crime scenes, but little DNA can be isolated from them. Historically, we could only look at small regions of mitochondrial DNA (mtDNA). With this new technology, we can sequence the entire mtDNA genome—16,569 nucleotides—from as little as 1 millimeter of hair shaft.

Q: How do you do this?
Holland
: We isolate DNA from the hair and then make copies of the mtDNA genome in small pieces. These small pieces are then placed on a flow cell, which is a small glass slide that has tens of millions of sequencing reaction centers. The magic is that they can all be sequenced at the same time. Before, we had to sequence individual bits of DNA in different tubes. Now, with massively parallel sequencing, we can look at the mtDNA genomes of dozens of people all at the same time.

Q: How is your research being used?
Holland
: Our goal is to advance the science and the methodologies used in crime labs. Because of projects like these, crime labs will have the technology to test hairs collected at crime scenes themselves rather than sending them off to a commercial lab. Massively parallel sequencing has really revolutionized molecular biology. Twenty-three years ago, when I worked on mtDNA sequencing for the disinterred remains of the American unknown soldier from Vietnam, we did it test tube by test tube.

Q: You had an interesting career in forensic science before coming to Penn State, including working on the remains of Sept. 11 victims.
Holland:
At that time, I was working for the Bode Technology Group in Springfield, Va. The office of the chief medical examiner in New York City sent us 13,500 skeletal samples—and we were lucky if we could process 50 bone samples at the time. We had to work quickly, because families were hurting and needed answers quickly. We got to the point where we were processing a thousand skeletal samples per week. Our work helped people grieve and bring closure to their families. It was an honor to be part of such an important project.

 

Mitchell Holland is a professor of biochemistry and molecular biology
and forensic science.