LIMESTONE, Maine — Forget textbooks and straight lectures — this isn’t your parents’ biology class.
For two weeks this month a small group of Maine School of Science and Mathematics students used a combination of laboratory time and cutting-edge technology to see what makes three distinct population groups in Maine tick — on the molecular level.
Six students in Debbie Eustis-Grandy’s January term biotechnology class took a close look at genetic differences among Acadians in the St. John Valley, Swedes of central Aroostook, and a random sample of MSSM students, along with data from the general U.S. population.
The students were looking at people’s DNA, specifically their “alleles” — tiny bits on chromosomes that are responsible for genetic coding.
“One of the lessons we learned from the Human Genome Project in 2006 was the vast majority of our DNA doesn’t specify particular traits such as eye color,” Eustis-Grandy said. “Scientists are unsure of the function of some of this material but it has accumulated over millions of years, [and] you can think of chromosomes like giant packrats, and many of these non-coding alleles are like the stuff you can’t bear to throw away.”
Scientists also have discovered that the frequency of some of these noncoding alleles is related to ethnicity, Eustis-Grandy said.
“I decided to look at two groups here in Maine,” she said. “We have these two distinct populations with the St. John Valley Acadians and the Swedish population, and I wanted to see if there would be any differences in the allele distribution.”
To start, Eustis-Grandy did some precourse legwork traveling around Aroostook County gathering samples. Willing donors were asked to “rinse and spit” with a saline solution to supply the genetic material.
In all, her students ended up with 32 samples from 10 Acadians, 10 Swedes and 12 fellow MSSM students taken as a random sample.
Back in the MSSM lab, the students used a chemical process to extract the DNA, which was then put through a polymerase chain reaction — or PCR — which Eustis-Grandy described as “sort of a molecular photocopier.”
Through PCR technology, researchers, in this case the MSSM students, can replicate specific alleles they wish to examine and study.
“There’s not a lot of high schools doing this,” Eustis-Grandy said. “Unlike the early days, now PCR is entirely automated and computerized.”
In order to artificially induce the specific allele replication, the samples must go through a highly controlled series of temperature changes.
“[The PCR device] is really just a fancy and computerized hot plate,” she said. “In the old days it was some grad student with three water baths and a stopwatch.”
After about three hours of PCR, the samples are then put through “gel electrophoresis” and staining, making the alleles visible to the naked eye.
At this point, Eustis-Grandy said, there are three possible results for each sample.
With the particular alleles chosen there can be evidence of two copies of the targeted allele, one from each parent; evidence of one copy from one parent only; or no copies.
In the first allele extracted, Eustis-Grandy said, the students saw the frequency between the French Acadians and random MSSM students was almost identical.
However, nine out of the 10 Swedes did not possess the allele.
“So the Swedish population was statistically different from the Acadians and the students,” Eustis-Grandy said. “But all three were statistically different from the general U.S. population.
“The explanation for these differences could be a reflection of Northern Europe versus Western Europe differences,” Eustis-Grandy said. “Maine has a strong history of French ancestry, so it is not too surprising the Acadian French and MSSM results were not statistically different,” since the genetic makeup of the students from Maine also has French in its background.
In the second allele all three groups differed statistically from each other, but only the Swedish samples differed from the general U.S. population.
“This was a little less clear-cut,” Eustis-Grandy said. “But it again could be a Northern European thing.”
A third allele extracted did not respond to the PCR process, she said.
“One really important lesson the students got was that not every analysis works every time,” she said. “They learned a lot about how science works.”
Part of seeing that science in action was a field trip to Jackson Lab in Bar Harbor.
Eustis Grandy also said she warned the students at the start of the course that she had no idea what the results would be.
“The biggest lesson might have been there are no given answers in science — you get what you get,” she said. “That can be disconcerting to students.”
Eustis-Grandy hopes to expand the class to a full semester course and widen her sample base.
“The Swedish samples were so statistically different I’d like to look at that more in-depth,” she said. “Of course, I think I’ve already sampled nearly every full-blooded Swede in New Sweden.”