Tagged: cell biology

the composition and functions of fungal cells

207: Ergot Alkaloids 0

207: Ergot Alkaloids

Ergot Alkaloids (EAs) belong to a large class of mycotoxins. They are primarily produced by fungi in the genera Claviceps and Epichloë, although Claviceps purpurea is responsible for most of the impacts on humans. EAs are most common in rye, but can be found in any cereal grain. The toxins were a significant problem in the middle ages, but modern agricultural techniques mean that exposure to enough EAs to cause symptoms is extremely rare.1,2 Sources Many fungi produce ergot alkaloids in many different plant hosts. Humans are impacted most by species of Claviceps, which infect seeds of grasses. The most problematic species is C. purpurea (see FFF#061), which infects rye. A variety of other species infect cereal grains but cause less contamination. Livestock can be sickened by infected grain or by ergot alkaloids produced by endophytes in pasture grasses, most notably by Epichloë coenophiala.1–3 This post focuses on Claviceps and...

Ochratoxin-producing molds 0

#206: Ochratoxins

Unlike most other mycotoxins found in food, the ochratoxins are primarily produced during food storage. Fungi in the genera Aspergillus and Penicillium are common molds that decompose a variety of foods, from grains to coffee to grapes. In the process, many of those fungi produce ochratoxins, which can damage the kidneys and cause cancer in many animals. Ochratoxins presumably impact humans the same way, but researchers have so far been unable to directly link ochratoxins to any human disease. This is probably because human consumption of ochratoxins is usually very low.

Fusarium molds 0

#205: Zearalenone

Zearalenone is a fascinating mycotoxin produced by Fusarium species. It is the only mycotoxin that mimics the effects of the hormone estrogen. In high doses, it causes sexual organs to develop incorrectly. Pigs are the most susceptible animals and suffer estrogenism and vulvovaginitis when exposed to high levels of zearalenone. The toxin is present in many grain-based foods intended for human consumption, but usually at very low levels. As a result, zearalenone is generally harmless to humans.

Fusarium verticillioides spores 0

#204: Fumonisins

Humans have very little to worry about from fumonisins, mycotoxins produced by Fusarium fungi that cause Fusarium ear rot disease of corn (maize). The toxins are linked with esophageal cancer, but scientists cannot prove that they cause cancer. However, fumonisins are a major problem for horses and pigs. In horses, the toxins cause liquefaction of the brain tissue, while in pigs they cause the lungs to fill with water.

Fusarium head blight 1

#203: Deoxynivalenol

Deoxynivalenol (DON) is a toxin found in grains infected with the fungus Fusarium graminearum and other Fusarium species. It is often called “vomitoxin” because it primarily causes vomiting in humans and livestock. Its long-term effects are mild, but it is still a very important mycotoxin because it is the most common mycotoxin found in food.

Aspergillus flavus 2

#202: Aflatoxins

Fungi produce innumerable “mycotoxins” – compounds that are toxic to humans. In mushrooms, these cause symptoms ranging from gastrointestinal upset to death (see FFF#091–100 for more). Although these are of significant concern to mushroom hunters, their impact is relatively small. The most significant mycotoxins in terms of the number of people affected are produced by molds that naturally grow on food. Over the next few weeks, I will discuss some of the most problematic food-borne mycotoxins. Topping that list are the aflatoxins, which cause liver cancer and are especially problematic for people in developing nations.

Fungi in the News Image 0

2017 Fall News Update

Fungi appear in the news with surprising frequency. However, many of those stories do not provide any new information. Below is a summary of what we’ve learned about fungi from August through October 2017. Read below to learn about: ballistospory, chromosome evolution, fighting fungal pathogens (in humans, bats, and bananas), psilocybin, oil-eating fungi, and more! Visit the associated links to get the full story.

Tremella mesenterica 0

#059 Tremella mesenterica, Witch’s Butter

One day as you check your mailbox you notice a yellow smear on the entrance to your house (for example a wooden gate). After retrieving your mail, you take a closer look and see that it’s a yellow gelatinous lobed blob – Witch’s Butter! Oh no, you think, I’ve been hexed by a witch! Knowing just what to do, you run back to the house, collect a few straight pins, and stab them through the offending substance to drain its juices and kill the spell. Unfortunately, this method doesn’t work very well for two reasons. First, this blob is actually the jelly fungus Tremella mesenterica. Like all jelly fungi, it is specifically designed to survive repeated dehydration and rehydration. Second, the main body of the fungus is still living inside the wood; unless you replace the wood, the mushroom will probably reappear in the same place!

sweet clover flowering 0

#195: Warfarin, from Cow Disease to Medicine

Warfarin is one of the most successful drugs of all time. Seventy years after it was first synthesized, warfarin is still the most widely prescribed anticoagulant. Warfarin has a unique story. What began as depression-era research into a mysterious disease of cattle ended up producing two life-saving medicines and a rat poison that are still in use today.

Fungi in the News Image 0

2017 Summer News Update

Fungi appear in the news with surprising frequency. However, many of those stories do not provide any new information. Below is a summary of what we’ve learned about fungi from May through early July 2017. Read below to learn about: early fungal fossils, fungal epigenetics, the best way to cook mushrooms, liver disease, malaria, and more! Visit the associated links to get the full story.