Fungal Pathogens May Be Adapting Dangerously to Global Warming : ScienceAlert
If you’ve played the video game The Last of Us, or watched any of the recent TV adaptations, you’ll be familiar with the idea of a mutated fungus infecting most of humanity – and now there’s some science to go along with that science. fiction.
While we’re not quite on the brink of a societal apocalypse like the one depicted in The Last of Us, researchers have demonstrated how pathogenic fungi can evolve in a warm climate to better withstand the heat inside our bodies.
Considering that it is heat that does most of the work to protect us from these threats, the implication is that these pathogens may become a greater disease threat as they adapt to an ever-warming planet. .
“These are not infectious diseases in the communicable sense; we don’t transmit the fungi to each other,” says molecular geneticist and microbiologist Asiya Gusa of Duke University School of Medicine in North Carolina.
“We inhale fungal spores all the time, and our immune system is equipped to fight them off.”
The team looked in detail at a pathogenic fungus called Cryptococcus deneoformans, placing it under laboratory conditions and raising its temperature from 30 °C (86 °F) to 37 °C (98.6 °F). These heat stresses significantly altered the genetic landscape of the fungus.
Specifically, there was more movement between ‘jump genes’, those transposable elements within DNA that can change position in the genome – five times more movement at the higher temperature, in fact. While these transposable elements do not directly produce proteins, they can affect how other genes work.
Three jump genes in particular were tracked: T1, Tcn12 and Cnl1. The changes they made within genes and the genome suggested they could change the way genes are coded and possibly cause drug resistance. It is not yet entirely clear what the end result of this increased activity may be.
Further tests were carried out in mice, where the activity of transposable elements was even more pronounced. Researchers think that being in an animal, with its immune response and other processes, can increase movement.
“We saw evidence of mobilization of all three transposable elements into the fungal genome within just 10 days of mouse infection,” says Gusa.
“These mobile elements likely contribute to adaptation to the environment and during an infection. This can happen even faster because heat stress accelerates the number of mutations that occur.”
It’s not yet time to build an underground bunker: this research is still in its early stages and does not involve actual human beings. Additionally, fungal spores are generally larger than viruses, so precautions like face masks will be more effective against them.
What the research shows is that increased heat promotes faster genetic changes in C. deneoformans. The bottom line is that dangerous fungi may be evolving faster than we thought as temperatures around the globe rise.
The next stage is the study of pathogens from people who have had a relapse of the fungal infection. Infections like this already kill hundreds of thousands of people a year, but for now it’s only those who are seriously immune-compromised. That may one day begin to change, and Gusa acknowledges the similar theme in The Last of Us.
“That’s exactly what I’m talking about – minus the zombie part!” says Gusa. “Fungal diseases are on the rise, largely due to an increase in the number of people who have weak immune systems or underlying health conditions.”
The research is published in PNAS.