In Carlson’s Class, It’s the Principle That Matters (i.e. Understanding It)

His students are sitting in a Yale classroom in New Haven in the 21st century, but John Carlson wants to transport them back to England in the mid-1960s.

He wants them to struggle alongside the scientists back then who were trying to identify the agent causing a strange brain-wasting malady that kills livestock — a kind of agent that may also eat holes in the brains of human victims.

The disease the scientists are studying is clearly infectious, but it does not seem to respond to treatments that kill bacteria and viruses, Carlson tells the undergraduates taking the introductory course “Principles of Molecular, Cellular and Developmental Biology.”

But, Carlson queries, what else could the killer be if not a virus or bacterium?

Carlson, a world leader in understanding the molecular mechanisms of the sense of smell, asks the class members how they would interpret a startling experiment the scientists did using ultraviolet (UV) light. Rates of infections for both viral and bacterial agents go down dramatically after prolonged exposure to UV light — so, Carlson notes, the material from brains of sick animals with this mysterious disease should become progressively less infectious the more it is dosed with UV light.

But that did not happen when those scientists did this experiment, he tells the class: Infection rates remained the same, no matter how long the infected tissue was exposed to the light. This experiment, he explains, was a key step in the scientists’ identification of a new infectious agent - a misfolded protein called a prion, which has been implicated in the “Mad Cow” outbreak as well as a number of human diseases.

“We were all amazed proteins could be a disease vector,” says Vina Pulido ‘10, who took Carlson’s class as a freshman, and still recalls the excitement of discovery that Carlson inspired. “What stood out for me was his passion for science.”

“I have one rule: make key principles clear and interesting,” says Carlson, the Eugene Higgins Professor of Molecular, Cellular and Developmental Biology.

That Carlson has succeeded in this goal is evidenced by the professor’s student reviews and his winning of the Dylan Hixon Award for Excellence in Teaching in the Natural Sciences in 1998.

Jamie Duke, a teaching assistant for the professor, says Carlson often immerses students in topical science questions and believes that one of the best ways is to put students into the shoes of researchers as they confront an interesting scientific problem.

“He says, ‘Here is the problem; here is an experimental technique to address the problem we are facing; here are the results and the conclusion,”’ Duke said. “You do not often see that level of detail in an introductory course.”

Students come into Carlson’s class with a wide range of majors, from history, economics and psychology, as well as molecular biology. So Carlson spends a lot of time in class preparation trying to hit the “sweet spot” — the level of sophistication that can keep future lab scientists engaged but not intimidate philosophy majors.

A major tool he employs is humor, and he is not afraid to use props, such as cuddly stuffed “germs” designed to represent micro-organisms such as Staphylococcus or the Ebola virus.

“What was interesting about Dr. Carlson is that he has this unassuming nerdy manner and then turns out to be hilarious,” said a student reviewer. “He also seems to love teaching.”

Carlson also feels strongly about the importance of research on simple organisms. Last fall he showed students in one of his graduate-level courses a YouTube video in which vice-presidential candidate Sarah Palin mocked grants to researchers studying fruit flies.

“I winced,” Carlson says. “So many great advances have been made studying simple organisms. Students and politicians need to understand this.” Carlson then invited Palin to attend the 50th annual worldwide gathering of fruit fly researchers, of which he is co-organizer.

He likes to tell his students the story of how scientists studying a single-cell pond organism discovered telomeres, the molecular caps on the end of chromosomes. The work led to dramatic advances in the understanding of human aging and cancer.

The goal of science teaching lies “not in learning an abundance of facts, because the importance of many facts can change,” Carlson says. Instead, he wants his students to understand the underlying principles, and how these principles were discovered. He also wants students to wonder at the many intriguing problems to be found in the biological world.

“What remains to be discovered is profound,” he says.

— By Bill Hathaway