- We always hear that stress is bad for you, but scientists want to know more about what exactly makes it so harmful.
- Animals and plants have microbiomes, which are the all the microscopic organisms (both good and bad) that live on and in an organism.
- We know that healthy microbiomes are good for living things (do you take probiotics?) and want to learn why. If a person has a wide variety of good microorganisms in her body, she is generally healthier than someone who has a low variety.
- Researchers at the University of Guelph in Canada know that microbiome diversity and stress are related, but wanted to find out how stress affects the microbiomes of animals in the wild.
- The researchers guessed that there would be a link between high levels of stress hormones called faecal glucocorticoid metabolites (FGM) and a low microbiome diversity.
- To test this, they set out 80 live-capture animal traps, suspended in trees in the forest, in order to catch red squirrels.
- They baited the traps with an oatmeal-peanut butter mixture (Umm, sounds delicious. I’d totally fall for that…) and they waited.
- Researchers checked the traps every two hours so the squirrels didn’t become overly stressed which could affect their baseline levels of stress hormones.
- They caught and tested 12 males and 12 females, tagged them, and took a mouth swab for and a sample of their feces. They captured these squirrels two separate times for sampling (it’s ok squirrels, I can’t resist peanut butter either).
- FGM hormones were extracted from the fecal samples, and DNA was studied from the microorganisms in the mouth swabs of the squirrels.
- Researchers looked at the diversity (number of individuals and number of species) of the microbiome of the squirrels.
- They compared the microbiome diversity to the FGM levels of the individual squirrels. They did this after the second capture as well to see if a change in the hormone level affected microbiome diversity.
- The researchers found that as the stress hormone FGM increased, the diversity of the squirrel’s microbiome decreased (there were fewer species of microorganisms AND fewer individual microorganisms living in the stressed-out squirrels).
- Male and female squirrels both had a similar decrease in microbiome diversity as their stress levels increased.
- One type of microorganism, Pasteurellaceae, actually increased in number as stress hormones increased. This particular microorganism has been linked to mass die-offs of big horn sheep and the near-extinction of Saiga antelope (read about the death of 134,000 of these animals in two weeks here).
- This is the first time that researchers have studied the affects of stress on microbiome diversity in animals in the wild.
- Squirrels are suckers for oatmeal and peanut butter.
- They found a link between elevated stress hormones and low microbiome diversity in red squirrels.
- Stress could be causing good microorganisms in our bodies to die which makes way for bad microorganisms to multiply to harmful levels.
- While a link, or correlation, is not necessarily a cause (this is so super super important to remember when reading about science, y’all), this is a big first step in research that could help scientists learn exactly how stress can affect microbiomes, and how those microbiomes can then affect the health of plants, animals and humans.
- Red squirrels are adorable even when they’re stressed.
I hear reading primary source articles has stress-reducing properties! Get your Zen AND your science on below:
Stress and the microbiome: linking glucocorticoids to bacterial community dynamics in wild red squirrels, Biology Letters, rsbl.royalsocietypublishing.org/lookup/doi/10.1098/rsbl.2015.0875