AP Biology class blog for discussing current research in Biology

Tag: Fungi

There’s A Fungus Among Us

Recent discoveries suggest that certain types of fungi that are responsible for severe lung infections have become more widespread in the United States. 

The first type of fungi, Histoplasma, responsible for histoplasmosis infections, was previously only found in the Midwest, and sporadically (no pun intended) found in parts of the East and South. 

Histoplasma pas-d

Medicare records from 2007 through 2016 reflect a serious cause for concern: 47 states and Washington D.C. have now reported a significant amount of cases of histoplasmosis. The second type of fungi, Blastomyces, which is responsible for the lung infection blastomycosis, has followed a similar pattern to Histoplasma

How do these infections occur? People inhale the spores from these harmful fungi, and they attack our immune systems. They do this by attacking B and T cells. The T and B memory cells ultimately remember the pathogen to prevent a repeated infection, and in the meantime, the cytotoxic T cells attempt to destroy the cells that the pathogen has already infected. The infection occurs if the immune system is unable to fight off the pathogens. 

Coccidioidomycosis is the third type of lung infection that has become more widespread. Coccidioides fungi used to only exist in the southwest, but have spread throughout the entire Western region of the United States. 

Letting these lung infections go undiagnosed can be fatal, so scientists hope that these recent discoveries will push doctors to test for fungi more frequently when confronted with patients that have lung infections.

Fungi’s Pacifist Defense Strategy

Recently, it’s been discovered by a group of student researchers at the University of Göttingen, Germany that the cells found in fungi that are typically responsible for the reproductive structures of the organism during overwintering periods also play a large role in the production of chemicals that protect the fungi from potential predators.

Due to the fact that fungi cannot move on its own in order to evade predators, they use chemicals to defend themselves by producing secondary metabolites. Secondary metabolites are not essential to the life of organisms, however they absolutely aid the fungi in their pursuit of avoiding predators and are beneficial for the organism’s survival. Some fungal secondary metabolites can even be fatal when eaten by humans, however most only consist of unappealing odor, color, and other physical attributes. Though not classified as plants, fungi and plants share many qualities and their production of secondary metabolites happens to be one of them and they produce them for the exact same reason too (their cells also both have a cell wall; that’s not really relevant but I wanted to include that because I find it interesting).

The proteins that are largely responsible for the production of most of these secondary metabolites are located in the Hülle cells of the fungus. Hülle cells play a vital role of the development and structure of fungi’s reproductive mechanisms. In order for the production of these secondary metabolites to be limited to that of an appropriate quantity, the “velvet complex” acts as a regulator for the pathways needed for production itself. A nearly perfect system. A flaw though, is if this process is interrupted for some reason, the organisms system of protection and its reproductive structures will both be impacted severely. Due to the fact that the protective chemicals use the reproductive structures as its main hub of production and storage, an interruption of the process would lead to a lack of development in both. This would be devastating to the organism not only because it is now vulnerable to predators but this lack of development of reproductive structures also inhibits the organism’s ability to reproduce.

Aspergillus nidulans wildtype

In the study, researchers observed woodlice and other arthropods that are predators of the fungi (they used A. nidulans for this study, a self fertilizing fungus (pictured above)) and how they respond to these secondary metabolites. It’s important to note that in this case the chemicals were not toxic to the arthropods, they simply made the parts of the fungus containing secondary metabolites undesirable for consumption (I include that not only to provide ethical clarity regarding the study for any readers that are curious but also to provide more information about the study as a whole). What the researchers found was that the predators only consumed parts of the organism that did not possess any secondary metabolites and they left areas that had many, such as its reproductive structures, completely alone. While I, like presumably many, don’t find this particularly surprising on the one hand; on the other it confirms that there is some sort of significance to the chemicals being produced and stored primarily in this region of the organism. Previous to this study, the importance of Hülle cells regarding the protection of fungi was completely unknown. In science, no matter what the field, discovery of any kind is a step in the right direction.

This study has shown that despite fungi’s immobility and lack of obvious protection, it has evolved in such a way that its system of shielding itself from potential threat is sophisticated, effective, and deceiving.

How Dandruff Can Lead to Crohn’s Cures

The Intro

Crohn’s disease is an inflammatory bowel disease (IBD) that causes inflammation of the digestive tract. Symptoms can include abdominal pain, malnutrition, stunted growth, and more on the gross side, diarrhea. There is no known cure for the condition, but a research team under David Underhill, “research chair for inflammatory bowel diseases at Cedars-Sinai Medical Center in Los Angeles,” has made a promising discovery in the gut microbiome. The researchers’ observations involve a microfungus present in and on our bodies, but before we unpack their findings, let’s figure out why the heck there are fungi inside our bodies and how all this relates back to dandruff!

The Mycobiome

There is a vast array of microbes that make their home in and around our person. This collection of organisms is known as the microbiome. While our microbiome consists of thousands of different microbial species, a whopping “99.9% of the total number of microbial cells belong to only a few species.” That other 0.1% of microbes is known as the “rare biosphere,” and within this diverse collection of organisms lies the mycobiome, the assortment of microscopic fungi that inhabit each and every one of us. While the microbiome has received lots of attention, especially in our gut area, research on the mycobiome’s effects on the human body is just beginning. Underhill’s team’s discovery gives us a glimpse into just how impactful these relatively rare organisms can be.

The Dandruff

So, what does dandruff from our scalp have to do with the fungi in our gut, and how does all this involve Crohn’s disease? Underhill and his researchers studied Malassezia, a fungus pretty much omnipresent in and around our bodies. It’s been known that a concentration of Malassezia on our scalps causes irritation that leads to dandruff. However, this fungus also inhabits our digestive tract. The research team found that “people with Crohn’s had high concentrations of Malassezia on their intestine walls, while healthy patients had almost none. The researchers then demonstrated that simply adding this type of fungi to the gut — at least, in mice — was enough to exacerbate the inflammation seen in Crohn’s.” Therefore, the same fungal substance that can cause minor dandruff may also be heavily responsible for a serious IBD that affects about 780,00 Americans. 

The Significance

Even though some patients may achieve permanent remission, as we noted before, there is not yet an established cure for Crohn’s disease. However, Underhill’s team’s study raises some questions that could help shape the future of IBD medical development. Could the current expensive, 60% effective anti-inflammatory medicine be replaced with simple antifungal drugs? If we prove that reducing fungus reduces intestinal inflammation, then antifungal Crohn’s cures could be accessible and affordable for thousands of people! In 5th grade, I was diagnosed with Crohn’s, and while my condition has improved, it’s far from cured. It’s exciting to hear about new discoveries that could lead to advances in treatment to help people like myself. Underhill’s team and another team of researchers in Montreal have already begun clinical trials with antifungal drugs, so depending on their results, we may be one big step closer to curing Crohn’s and other inflammatory bowel diseases alike!

I think these discoveries are important and worth talking about, so if you have anything to add, challenge, or discuss, feel free to comment below! Thanks for reading!


Zombie Apocalypse? Yes, it’s happening right now.

Most of us would think that a zombie apocalypse is simply a fantasy seen in scary movies. However, in Brazil, this freaky fantasy has rapidly turned into reality for some unfortunate carpenter ants. In the Brazilian rainforests, one could find carpenter ants whose jaws are forever locked onto a leaf, with a fungus growing right through the dead ant’s face. This is a result of the deadly zombie-like fungi that is brutally murdering ants, otherwise known as Ophiocordyceps unilateralis. 

Ophiocordyceps unilateralis initially infects its victims through spores that are launched from other zombie-ant fungi. The fungus initially penetrates the ant’s exoskeleton as singular cells, but eventually begins multiplying rapidly to form an inviolable fungal network.  This network engulfs the ant’s nervous system and muscles, and eventually the ant capitulates to the parasitic fungi. The ant slowly begins to deteriorate, beginning with simple actions like leaving its colony, to eventually losing full control of its body and dying. However, before the horrible death that the ant suffers, lots of actions take place within the ant’s body. After leaving its colony, the fungi commands the ant to move to a height of approximately 10 inches above the ground. This is done because it is the ideal height for the humidity that the fungi needs to proliferate and flourish inside the ant’s body. Next, the fungi commands the ant use its jaws to permanently form a death grip into a twig or leaf, so it will never move its body ever again. After inevitably killing the ant, the fungi proceeds to grow right through the face of the ant, where it will consequently release more spores to be spread to other ants. Over time, the fungi will spread quickly, and zombify entire colonies of ants.

It’s seriously wild to think that fungi in Brazilian jungles are brutally murdering and zombifying ants by taking over their entire bodies! Moreover, it is crazy that something as simple as a single celled fungi that enters an ant’s blood flow is powerful enough to expeditiously wipe away an ant’s entire life. With over 400 different species of this fungi in the wild, we can expect the ant zombie apocalypse to continue in the jungles of Brazil.




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