Lecture 21: Fungi V Flashcards
What are secondary metabolites?
Small bioactive molecules with toxic and medicinal properties. Many are toxins.
What is the use of secondary metabolites?
They are often repurposed as pharmaceuticals
Give 2 examples of drugs derived from bacterial metabolites.
Penicillin and cephalosporins
Give 2 examples of drugs derived from fungal metabolites.
Amphotericin and echinocandins
What are the 3 medical applications of fungal products?
Medications, enzymes, and acids
Give an example of an immunosuppressive medication that comes from fungal metabolites.
Cyclosporine, which kills T cells to prevent an autoimmune response to grafts and organ transplants
Give an example of a lipid lowering medication that comes from fungal metabolites.
Statins, which target cholesterol
Give 3 examples of transgenic medications. How are they made?
Hydrocortisone, which reduces inflammation, Hepatitis B vaccine, and HPV virus vaccine. They are made by yeasts.
Give 2 examples of enzymes derived from fungal metabolites.
Glucoamylase and alpha-galactosidase for fermentation of food, ligninases for biobleaching of paper
Give 2 examples of acids derived from fungal metabolites.
Citric acid and gluconic acid, both of which are used in soft drinks.
Give 3 examples of how the food and beverage industry uses fungal metabolites.
Mushrooms, cheese, and fermentation (wine, beer, alcohol, chocolate)
How do fungi fit into the production of chocolate?
Cacao beans are inedible until fermented by a complex process involving yeasts and molds.
What is the function of fungi in wooded environments?
They digest lignin and cellulose for ants that cannot do it themselves by growing hyphal mats of Leucococcus sp. The ants create gardens of leaf cuttings that the fungi can feed on, while ants harvest and feed on the fungal hyphae (symbiosis).
What is the difference between a toxin and a mycotoxin?
Toxins can come from any microorganisms, while mycotoxins are specifically secondary metabolites made by fungi.
What fungal species are “Death Angel” mushrooms? What do they produce?
Amanita and Galerina species. They release Amatoxins, which are mycotoxins.
What mycotoxin is responsible for most deaths from mushroom poisoning?
Amatoxins from death angel mushrooms.
What is the lethal dose for death angel amatoxins?
0.1 mg/kg
What are the symptoms of death angel amatoxins?
Abdominal pain and liver damage
How are amatoxins affected by heat?
They are heat stable and unaffected by drying, meaning that they can’t be cooked or boiled away.
What part of the body do amatoxins accumulate in?
They are absorbed in the GI tract and concentrate in the liver and kidney cells.
What is the mechanism of action of amatoxins?
They binds to RNA polymerase II and prevent its translocation along the DNA strand after the first phosphodiester bond is formed. This results in impaired RNA production and failed protein synthesis.
What fungus produces aflatoxin?
Arpergillus flavurs
What is the most important toxin in world food crops?
Aflatoxin
How does aflatoxin respond to heat?
They are stable, so they can appear in processed foods.
How does the consumption of aflatoxins affect animals and humans?
They can kill animals quickly and cause liver cancer in humans.
Describe the mechanism of action of aflatoxin.
It forms DNA adducts and induces a G:C to T:A mutation at codon 249 of the p53 tumour suppressor gene, which causes cancer.
St. Anthony’s Fire is also called […]
Ergot toxin
Ergot toxin is produced by which fungus?
Claviceps purpurea
Ergot toxins are contained in structures called […], which are […]
Sclerotia, highly resistant portions of the mycelia of the fungus that can detach
What is the major effect of ergot on humans?
It can cause hallucinations, as it is a natural source of LSD.
Name the 3 major symptoms of ergot on humans aside from what is it most known for.
Aside from hallucinations, it can cause a burning sensation in the limbs, seizures and movement disorders, and can prevent proper blood circulation in the body.
Ergot is associated with which historical event?
The Salem Witch trials, as after they experienced the symptoms of ergot after consuming rye in moist weather, it was believed that they were due to witchcraft.
