For Frogs, Surviving the Heat Could Come Down to What Is in Their Gut

Amphibians are the most threatened vertebrate class worldwide. Because they lack the ability to regulate their own temperature and moisture levels, climate change is playing a significant role in this growing peril (1). Climate change impacts amphibian survival in several ways. In addition to habitat loss, growing drought conditions make maintaining body moisture levels challenging and warming temperatures restrict activity periods needed for reproduction as well as increasing the risk of heat stress.

Heat tolerance varies by species, and understanding what influences these differences could help predict species survival. The gut microbiota is known to affect a wide range of functions in host animals, and recently studies have begun to investigate its role in host thermal tolerance (2).

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Gut Microbes and Hypertension: Demonstrating a Causal Link

Most of us are aware that the human body is covered by and full of microorganisms. And we understand that most of these microorganisms are helpful, both in terms of competition with and protection against invading microorganisms, and in the gut, as agents of digestion.

Bacillus subtilis, an example of Firmicutes, and not a good gut microbe. By Y tambe (original uploader) - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=49528
Bacillus subtilis, an example of Firmicutes, and not a good gut microbe. By Y tambe (original uploader) – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=49528

In the past decade, however, research has brought compelling details implicating gut microbes in obesity, cancer, insulin resistance and such central nervous system disorders as depression, austism spectrum disorder and multiple sclerosis (Adnan, S. et al.). Yet the mechanisms and details of these associations have not been fully demonstrated.

Gut microbes have been proven to be connected to thickening of heart vasculature, known as atherosclerosis. Researchers have demonstrated that bacteria metabolize choline and L-carnitine from food to trimethylamine, which crosses the gut barrier into circulation and reaches the liver. In the liver, trimethylamine is metabolized to the atherogenic molecule triethylamine-N-oxide (Gregory, J.C. et al., Brown and Hazen). These studies are among the few that provide a direct connection between gut microbes and a pathological condition.

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