Fungi inside us: California bats under siege | UCR News

As spooky season arrives, a creepy fungus is infesting California's bat population, threatening their survival.

The fungus was first detected on the East Coast around 2006 and has continued to spread westward ever since. It made headlines this week because it was definitely spotted in the Golden State and may have already made it as far south as San Bernardino County.

How does this killer work, how did it get here, and what does it mean for humans? To answer these questions, researchers from the Department of Microbiology and Plant Pathology at the University of California, Riverside Two mycologists, Professor Jason Stajic and Associate Professor Sidney Glassman, answer.

What is this fungus? Where did it come from?

Starzic: Pesudogymnoascus destructans or Pd may have originated in Europe, but may also have origins in Asia. It may have been introduced to North America as a pathogen around 2006.

Samples of the virus across the United States generally have exactly the same genetic makeup, suggesting the virus is spreading rapidly. It is hoped that humans visiting the caves may be moving soil and spores, helping spread the virus.

this map The U.S. Geological Survey shows how it's spreading every year. Sadly, we've seen this shift from east to west and now we're seeing a shift from north to south. Since it is a cold-adapted bacterium, I am interested in how it is spreading within the state, or if there are still local adaptations to temperature differences.

Glassman: This causes something called white-nose syndrome, where a bat's muzzle and wings become white and fuzzy. This damages the wings, but also makes the bat more active. If you move your body further, your fat will be used up and you will starve to death. You can travel through bat droppings (guano) to reach the bats in the cave.

Does this fungus pose a danger to humans?

Glassman:Unlikely to affect humans, unless one considers the knock-on effects of eliminating bats, which eat large numbers of mosquitoes, which are carriers of diseases that affect humans. This means that if bats aren't helping to control mosquitoes, humans could be indirectly exposed to more diseases.

Starzic: As the climate continues to change, some fungi are adapting to warmer temperatures. In doing so, they may acquire traits that allow them to colonize other mammals more effectively.

The fungus itself is sensitive to ultraviolet light and high temperatures, so further adaptations will be needed to make the leap as a competent human pathogen. In general, this is a skin disease that does not require survival at human body temperature (37°C), so its transition to a true human pathogen requires some changes in its biological properties.

How do bacteria work?

Starzic: Secretes enzymes called peptidases that damage connective tissue in bats. It can appear as a white, fuzzy mold on the bat's skin and tissues. It invades tissues and causes damage. The worst cases occur in the connective tissue of the wings, impairing the ability to fly and hunt, further reducing food intake and limiting the ability to recover from disease. Although some bats have developed immunity and populations are recovering in some areas, the means to determine what genotypes are surviving in bat populations is still being studied. I think so.

In nature, everything has a role, even fungal predators. How does this fungal predator benefit the environment?

Starzic: More generally, the role of fungi in the environment is cycling nutrients. These provide a means to break down complex molecules such as lignin and cellulose in plants and proteins in dead animals, releasing carbon and nitrogen for these organisms.

In a cave, the only food sources are what is brought in by the environment and animals that pass through the cave. Therefore, the fungi that live there must make effective use of the materials present.

I don't usually think of these in terms of predator and prey. This is an opportunistic pathogen that probably initially had some foothold in weaker or younger bats. Over time, it evolved and became more successful. However, European bats have evolved with it and are not harmed in the same way. In Europe, Pd may not be called a pathogen at all.

Glassman: I agree that most things play a role in the environment, but this pathogen was introduced here beyond its natural range, and what North American bats are doing about it. I don't have any resistance either, so I would say this is an example of what I can do. There is no conceivable benefit from this particular fungus.

Natural pathogens usually serve to keep populations from getting too out of control, but if they are introduced elsewhere, resistance due to other factors such as globalization and rainforest clearing It is unknown and can often have devastating consequences for the prey.

What are some interesting things to note about this fungus that we haven't asked yet?

Starzic: Research by Bruce Klein of the University of Wisconsin and David Brehart of the USGS in Madison, Wis., is underway to develop a vaccine strategy against Pd.

There are similar interesting stories about other recently emerging fungal diseases of wildlife. In addition to those that affect bats, some also affect snakes and amphibians. They have all evolved means to effectively degrade vertebrate tissue.

Evolutionarily, they constitute very distinct and distinct lineages among the fungi, and the fungi have undergone multiple or repeated transitions to be able to colonize and overtake these animals. It shows that All of these fungal diseases are recognized as having emerged within the past 20-30 years, so there are clear changes in how they spread in the environment and, at least in part, are linked to humans. It seems that there is.

Witches, be careful! Thanks to the emergence of this relatively new fungal disease, it may soon become difficult to produce drugs that require newt eyes, snake fangs, and bat wings.

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