Lecture 21: Fungi V

Question 1

What are secondary metabolites?

Answer 1

Small bioactive molecules with toxic and medicinal properties. Many are toxins.

Question 2

What is the use of secondary metabolites?

Answer 2

They are often repurposed as pharmaceuticals

Question 3

Give 2 examples of drugs derived from bacterial metabolites.

Answer 3

Penicillin and cephalosporins

Question 4

Give 2 examples of drugs derived from fungal metabolites.

Answer 4

Amphotericin and echinocandins

Question 5

What are the 3 medical applications of fungal products?

Answer 5

Medications, enzymes, and acids

Question 6

Give an example of an immunosuppressive medication that comes from fungal metabolites.

Answer 6

Cyclosporine, which kills T cells to prevent an autoimmune response to grafts and organ transplants

Question 7

Give an example of a lipid lowering medication that comes from fungal metabolites.

Answer 7

Statins, which target cholesterol

Question 8

Give 3 examples of transgenic medications. How are they made?

Answer 8

Hydrocortisone, which reduces inflammation, Hepatitis B vaccine, and HPV virus vaccine. They are made by yeasts.

Question 9

Give 2 examples of enzymes derived from fungal metabolites.

Answer 9

Glucoamylase and alpha-galactosidase for fermentation of food, ligninases for biobleaching of paper

Question 10

Give 2 examples of acids derived from fungal metabolites.

Answer 10

Citric acid and gluconic acid, both of which are used in soft drinks.

Question 11

Give 3 examples of how the food and beverage industry uses fungal metabolites.

Answer 11

Mushrooms, cheese, and fermentation (wine, beer, alcohol, chocolate)

Question 12

How do fungi fit into the production of chocolate?

Answer 12

Cacao beans are inedible until fermented by a complex process involving yeasts and molds.

Question 13

What is the function of fungi in wooded environments?

Answer 13

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).

Question 14

What is the difference between a toxin and a mycotoxin?

Answer 14

Toxins can come from any microorganisms, while mycotoxins are specifically secondary metabolites made by fungi.

Question 15

What fungal species are “Death Angel” mushrooms? What do they produce?

Answer 15

Amanita and Galerina species. They release Amatoxins, which are mycotoxins.

Question 16

What mycotoxin is responsible for most deaths from mushroom poisoning?

Answer 16

Amatoxins from death angel mushrooms.

Question 17

What is the lethal dose for death angel amatoxins?

Answer 17

0.1 mg/kg

Question 18

What are the symptoms of death angel amatoxins?

Answer 18

Abdominal pain and liver damage

Question 19

How are amatoxins affected by heat?

Answer 19

They are heat stable and unaffected by drying, meaning that they can’t be cooked or boiled away.

Question 20

What part of the body do amatoxins accumulate in?

Answer 20

They are absorbed in the GI tract and concentrate in the liver and kidney cells.

Question 21

What is the mechanism of action of amatoxins?

Answer 21

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.

Question 22

What fungus produces aflatoxin?

Answer 22

Arpergillus flavurs

Question 23

What is the most important toxin in world food crops?

Answer 23

Aflatoxin

Question 24

How does aflatoxin respond to heat?

Answer 24

They are stable, so they can appear in processed foods.

Question 25

How does the consumption of aflatoxins affect animals and humans?

Answer 25

They can kill animals quickly and cause liver cancer in humans.

Question 26

Describe the mechanism of action of aflatoxin.

Answer 26

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.

Question 27

St. Anthony’s Fire is also called […]

Answer 27

Ergot toxin

Question 28

Ergot toxin is produced by which fungus?

Answer 28

Claviceps purpurea

Question 29

Ergot toxins are contained in structures called […], which are […]

Answer 29

Sclerotia, highly resistant portions of the mycelia of the fungus that can detach

Question 30

What is the major effect of ergot on humans?

Answer 30

It can cause hallucinations, as it is a natural source of LSD.

Question 31

Name the 3 major symptoms of ergot on humans aside from what is it most known for.

Answer 31

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.

Question 32

Ergot is associated with which historical event?

Answer 32

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.