Sid Douglas

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In a finding that scientists are calling “beyond surprising,” the decades-long series of outbreaks of leukemia among clams on the eastern North American coast has been attributed the spreading of cancer from one clam to another. The finding has prompted scientists to reassess the assumption that contagious cancers are rare occurrences in nature.

“I think the story is a great example of remarkable biology lying hidden right under our noses — we just have to go looking,” Dr. Stephen Goff of the Howard Hughes Medical Institute and Columbia University told The Speaker. “It reminds us that there are many surprising aspects of nature yet to be discovered. And today we have very powerful new tools that allow us to make these discoveries.”

The team based their conclusion — that a single incidence of cancer was the root of the decades of leukemia outbreaks that have occurred off of the American and Canadian eastern coasts — on findings that the genotypes of the tumor cells come from a single line of tumor cells, not from the host animals own cells. This “rogue clonal cell line,” as the researchers put it, grew, divided, and broke free from the ground zero Steamer clam to infect others.

“That was the biggest surprise, for sure,” Dr. Goff told us. “An earlier, less exciting, surprise was the finding of the huge increase in the copy number of the Steamer retroelement in the tumors,” he added. “It’s the biggest increase in copy number of a mobile element in nature that I know of.”

The team is continuing their research, pushing to understand more about how the cancer became contagious. It is not yet known where the disease began not how the disease transmits between clams.

“We are actively seeking answers to the following questions: What are the mutation(s) that allow the tumor line to do this? Did the Steamer element cause these mutations? When did the original tumor arise? How long has it been spreading? Is this line restricted to the species of origin (the soft-shelled clam) or can it spread to other species? Do other species have similar tumor lines of their own?”

The transmissible cancer studied by the team is not the only known wild case, but the existence of transmissible cancer in nature has previously been considered a rare occurrence.

“We would normally expect this to be rare,” Goff told us. “We know of only two other examples in all of nature: the facial tumors of the Tasmanian Devil, and a canine venereal tumor — both are discussed in the paper, and you can read their histories. We think examples like this are rare — in vertebrates — because the adaptive immune system would recognize an invading tumor cell as foreign and reject it. The Devils do not reject these tumors for a special reason: the animals are almost all genetically identical, having gone through a small bottleneck — they almost went extinct. The dog tumor is special in lacking the surface markers that would mediate the rejection.

“But we suspect these transmissible cancers could well be more common (than we would ever have imagined) in invertebrates. They have only a primitive innate immune system, and the tumor cells must be able to evade this system and invade the new host.

“For this to happen, the tumor has to have evolved to be able to exit from one diseased animal, find its way into a healthy animal — in this case, in the sea — and colonize the new animal. It’s an extreme version of metastasis, where a tumor sheds cells that seed new locations within an individual. Here the tumor is moving into an entirely new animal — not just within an animal.

“The recent research expands our conception of transmissible cancers — they exist not only on land but in a marine environment as well — and this has prompted the researchers to suspect that contagious cancers are more common in nature than we had thought.”

The report, “Horizontal Transmission of Clonal Cancer Cells Causes Leukemia in Soft-Shell Clams,” was completed by Michael J. Metzger, Carol Reinisch, James Sherry and Stephen P. Goff, and was published in the journal Cell.

By Sid Douglas

Images by the research team. Clam photo by Michael J. Metzger

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People are unaware that various innocuous-sounding things are actually affecting them on a regular basis, according to new research by Bayer College of Medicine. Newspapers, radio and tv can influence the way people act by using words that trigger powerful emotions, the researchers found–clean words cause clean thoughts, which produce ethical actions, and dirty words produce disgusted thoughts and immoral actions.

“People don’t know it, but these small emotions are constantly affecting them.” said Vikas Mittal, J. Hugh Liedtke Professor of Marketing Adjunct Professor of Family & Community Medicine, Baylor College of Medicine, and lead researcher on the study.

“What we found is that unless you ask people, they often don’t know they’re feeling disgusted,” Mittal said. “Small things can trigger specific emotions, which can deeply affect people’s decision-making. The question is how to make people more self-aware and more thoughtful about the decision-making process.”

This is because disgust is an emotion that causes people to protect themselves–that is, focus on their self.

However, lessening disgust causes people to behave more ethically again. This can be done by causing people to think of clean things–cleaning products such as Kleenex or Windex, for example. When disgust is lessened, the likelihood of cheating goes away.

The study involved two sets of randomized experiments with 600 participants. The researchers randomly disgusted their participants in three ways.

In one, participants evaluated antidiarrheal medicine, diapers, cat litter, feminine care pads and adult incontinence products. In another experiment, participants wrote out their most disgusting memory. In a third, a disgusting scene from the film “Trainspotting” was played for the participants. The scene shows a man diving into a dirty toilet.

The disgusted participants engaged in consistently self-interested behaviors at a significantly heightened rate.

After the participants were disgusted, another set of experiments was conducted.

The researchers had some participants evaluate cleaning products–disinfectants, body washes, household cleaners. These participants were returned to a normal level of deceptive behavior.

Managers could use this information to understand how to impact decision-making and cause ethical or unethical behavior, Mittal said. He commented on office cleanliness and cleanliness in the workplace in general.

“At the basic level, if you have environments that are cleaner, if you have workplaces that are cleaner, people should be less likely to feel disgusted,” said Mittal. “If there is less likelihood to feel disgusted, there will be a lower likelihood that people need to be self-focused and there will be a higher likelihood for people to cooperate with each other.”

“If you’re making important decisions, how do you create an environment that is less emotionally cluttered so you can become progressively more thoughtful?”

The report, “Protect Thyself: How Affective Self-Protection Increases Self-Interested Behavior,” was authored by Mittal and Karen Page Winterich, associate professor of marketing at Penn State’s Smeal College of Business, and Andrea Morales, a professor of marketing at Arizona State’s W.P. Carey School of Business, and will be published in the journal Organizational Behavior and Human Decision Processes.

By Sid Douglas