Slime molds crack 3 of the biggest issues in the U.S.

The Plasmodium Consortium seeks to get answers to America’s problems from slime molds.

Three petri dishes of the Plasmodium Consortium (Ray Mendel)

The Plasmodium Consortium is a new policy research institute attached to Hampshire College in Massachusetts. At an event on March 2, their secretary, experimental philosopher and conceptual artist Jonathon Keats, announced the group has cracked three of America’s most vexing and controversial problems: the destruction of our climate, the opioid epidemic, and immigration. The Consortium’s secret? It brings a unique perspective to these issues. “They're all slime molds," says Keats. This is the first analysis of these issues by non-human scholars, he notes, asserting, “Their advice is objective, and transcends our polarized political environment because they don't belong to our species." (A slime mold was previously appointed to the Hampshire faculty.)


Specifically, the consortium is comprised of Physarum polycephalum slime molds, and we’ve reported before on their surprising learning, memory, and problem-solving capabilities, even though they completely lack neurons and a brain. The slimes solve problems and build knowledge using “habituated learning,” in which their behavior changes over time in response to a repeated stimulus.

(Thom Long)

The project is interdisciplinary, involving faculty and students — and slime molds, or course — and its results were presented in the Hampshire College Art Gallery from January 29 to March 2, 2018.

Keats explains in the project’s press release, “…from the beginning, we've believed that slime molds were equally capable of researching more abstract problems. Over billions of years, they've had to overcome challenges including ice ages and collisions with asteroids — events even more calamitous and varied” than those the U.S. is trying to resolve. The Consortium’s conclusions are based on experiments that distill expansive issues to their underlying questions and devise models that allow slime molds, (somehow) brainless experts that they are in problem-solving, to come answer them.

Choosing a healthier environment

To ascertain the most logical, sound response to life in a degraded environment — such as one produced by offshore drilling, excessive manufacturing, and pollution — the Consortium set up an experiment to test the appeal and benefits of a less-polluted environment for their scholars.

The experiment involved the creation of two pastes made of oats for nutrition and salt, which slime molds avoid. The first had a lower amount of the mineral, and the second was saltier. Petri dishes of nutrient-free agar were prepared, with the first paste placed on one side, and the second on another.

(Ray Mendel)

Slime molds placed in the centers of the dishes consistently moved to the less salty paste, revealing their preference for a non-toxic environment. A second experiment used intermittent flashes of light to simulate environmental instability to see if that had any effect on slime mold choices — the results are not reported in the Consortium’s publication.

Addiction study

The Consortium also looked at marijuana legalization. While some consider grass a gateway drug to harder substances such as opioids, others assert that “people can be weaned from hard drugs with access to less harmful ones,” according to the Consortium’s report. They performed two experiments to see how slime molds are drawn to a favorite chemoattractant, valerian root as opposed to a useful nutrient.

In the first experiment, they were given a simple choice: pure valerian vs. pure nutrient. This binary choice — modeling a nation in which marijuana is not legal and the only choice is hard drugs or none — resulted in something that looked a lot like the growing opioid epidemic.

In a second experiment, pure valerian was placed at the center of dishes with concentric rings containing progressively less valerian and more nutrient moving outward to an outer zone of pure nutrient.

(Ray Mendel)

The results were summarized in a letter the Consortium sent to U.S. Attorney General Jeff Sessions:

Confronted with a binary choice between a highly-addictive chemical and a nutritionally-balanced meal, slime mold populations will consistently choose the former, with consequences that can be fatal. However when presented with a chemical gradient between the addictive substance and nutrients — equivalent to availability of gateway drugs in a human environment — slime molds show a distinct tendency to migrate from the former toward the latter, but not from the latter to the former, a choice that improves their chance of survival. 

Benefits of a border wall, or not

The third study looked at the effect of a divider — a border wall — separating two populations of Physarum polycephalum, and how that affected the health of both groups.

For this, two populations of slime molds are placed on opposite sides of a petri dish, with one side having only protein as nutrition, and the other die exclusively carbohydrates. Slime molds prefer a balance of the two. Four scenarios were constructed:

  1. The populations were separated by sealed plexiglass wall.
  2. A border control was simulated using an illuminated central strip presenting a risk factor and thus a deterrent to crossing.
  3. A porous border control was simulated using an intermittent illuminated central strip.
  4. No barrier existed between populations.

(Ray Mendel)

The slime molds were observed after 72 hours, and their health measured by the surface area covered. The populations unimpeded by a border were clearly thriving most successfully.

Scenario 4 above (Ray Mendel)

A central region also developed in which the two populations combined to create a third. From this, the Consortium concluded that instead of a border controlling immigration between physically adjacent areas — such as the U.S. and Mexico — an international zone could be beneficial since “the unconstrained slime molds were found to join together and thrive in the open border zone, suggesting that borders may be especially vital regions if allowed to develop without government interference. 

Seriously?

Keats has been behind a variety of thought experiments like this one, and on one level it’s all in fun, while on another, it’s deadly serious. One may question the value of the new Consortium’s conclusions, suggesting their experiments simply reveal the obvious. But that’s the point. So many of the questions the U.S. faces are not really that complex — their answers are obvious. They’re just made to seem complicated by those who dislike the answers any Physarum polycephalum can plainly “see.”

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Image source: Vaccaro et al, 2020/Harvard Medical School
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We don't have to tell you what it feels like when you don't get enough sleep. A night or two of that can be miserable; long-term sleeplessness is out-and-out debilitating. Though we know from personal experience that we need sleep — our cognitive, metabolic, cardiovascular, and immune functioning depend on it — a lack of it does more than just make you feel like you want to die. It can actually kill you, according to study of rats published in 1989. But why?

A new study answers that question, and in an unexpected way. It appears that the sleeplessness/death connection has nothing to do with the brain or nervous system as many have assumed — it happens in your gut. Equally amazing, the study's authors were able to reverse the ill effects with antioxidants.

The study, from researchers at Harvard Medical School (HMS), is published in the journal Cell.

An unexpected culprit

The new research examines the mechanisms at play in sleep-deprived fruit flies and in mice — long-term sleep-deprivation experiments with humans are considered ethically iffy.

What the scientists found is that death from sleep deprivation is always preceded by a buildup of Reactive Oxygen Species (ROS) in the gut. These are not, as their name implies, living organisms. ROS are reactive molecules that are part of the immune system's response to invading microbes, and recent research suggests they're paradoxically key players in normal cell signal transduction and cell cycling as well. However, having an excess of ROS leads to oxidative stress, which is linked to "macromolecular damage and is implicated in various disease states such as atherosclerosis, diabetes, cancer, neurodegeneration, and aging." To prevent this, cellular defenses typically maintain a balance between ROS production and removal.

"We took an unbiased approach and searched throughout the body for indicators of damage from sleep deprivation," says senior study author Dragana Rogulja, admitting, "We were surprised to find it was the gut that plays a key role in causing death." The accumulation occurred in both sleep-deprived fruit flies and mice.

"Even more surprising," Rogulja recalls, "we found that premature death could be prevented. Each morning, we would all gather around to look at the flies, with disbelief to be honest. What we saw is that every time we could neutralize ROS in the gut, we could rescue the flies." Fruit flies given any of 11 antioxidant compounds — including melatonin, lipoic acid and NAD — that neutralize ROS buildups remained active and lived a normal length of time in spite of sleep deprivation. (The researchers note that these antioxidants did not extend the lifespans of non-sleep deprived control subjects.)

fly with thought bubble that says "What? I'm awake!"

Image source: Tomasz Klejdysz/Shutterstock/Big Think

The experiments

The study's tests were managed by co-first authors Alexandra Vaccaro and Yosef Kaplan Dor, both research fellows at HMS.

You may wonder how you compel a fruit fly to sleep, or for that matter, how you keep one awake. The researchers ascertained that fruit flies doze off in response to being shaken, and thus were the control subjects induced to snooze in their individual, warmed tubes. Each subject occupied its own 29 °C (84F) tube.

For their sleepless cohort, fruit flies were genetically manipulated to express a heat-sensitive protein in specific neurons. These neurons are known to suppress sleep, and did so — the fruit flies' activity levels, or lack thereof, were tracked using infrared beams.

Starting at Day 10 of sleep deprivation, fruit flies began dying, with all of them dead by Day 20. Control flies lived up to 40 days.

The scientists sought out markers that would indicate cell damage in their sleepless subjects. They saw no difference in brain tissue and elsewhere between the well-rested and sleep-deprived fruit flies, with the exception of one fruit fly.

However, in the guts of sleep-deprived fruit flies was a massive accumulation of ROS, which peaked around Day 10. Says Vaccaro, "We found that sleep-deprived flies were dying at the same pace, every time, and when we looked at markers of cell damage and death, the one tissue that really stood out was the gut." She adds, "I remember when we did the first experiment, you could immediately tell under the microscope that there was a striking difference. That almost never happens in lab research."

The experiments were repeated with mice who were gently kept awake for five days. Again, ROS built up over time in their small and large intestines but nowhere else.

As noted above, the administering of antioxidants alleviated the effect of the ROS buildup. In addition, flies that were modified to overproduce gut antioxidant enzymes were found to be immune to the damaging effects of sleep deprivation.

The research leaves some important questions unanswered. Says Kaplan Dor, "We still don't know why sleep loss causes ROS accumulation in the gut, and why this is lethal." He hypothesizes, "Sleep deprivation could directly affect the gut, but the trigger may also originate in the brain. Similarly, death could be due to damage in the gut or because high levels of ROS have systemic effects, or some combination of these."

The HMS researchers are now investigating the chemical pathways by which sleep-deprivation triggers the ROS buildup, and the means by which the ROS wreak cell havoc.

"We need to understand the biology of how sleep deprivation damages the body so that we can find ways to prevent this harm," says Rogulja.

Referring to the value of this study to humans, she notes,"So many of us are chronically sleep deprived. Even if we know staying up late every night is bad, we still do it. We believe we've identified a central issue that, when eliminated, allows for survival without sleep, at least in fruit flies."

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