Mycotoxins

Question 1

What are the two routes of exposure to mycotoxins?

Answer 1

oral (consumption) and inhalation

Question 2

What are the major concerns in regards to exposure to mycotoxins?

Answer 2

Chronic toxicity in humans, acute toxicity in livestock, economic losses and reduced crop yield and quality

Question 3

What are some conditions that favour the growth of moulds?

Answer 3

warmth and moisture, insect damage and other diseases-however a period of drought can increase a plants susceptibility to a fungus

Question 4

What are the two aspergillus and penicillium species discussed in class?

Answer 4

Aflatoxins and Ochratoxins

Question 5

What species produce aflatoxins?

Answer 5

Aspergillus flavus and aspergillus parasiticus

Question 6

What are the structures of aflatoxins?

Answer 6

B1, B2, G1 and G2

Question 7

What is the LD50 of aflatoxin?

Answer 7

0.5-20mg/kg

Question 8

What are the main sources of alfatoxins?

Answer 8

peanuts, corn, tree nuts, dried fruit and cottonseed

Question 9

What led to the discovery of aflatoxins?

Answer 9

100,000 turkeys dying in England in the 1960s due to brazil nuts being present in their feed

Question 10

What is aflatoxins MOA?

Answer 10

binds guanine in DNA which inhibits mRNA synthesis and thus protein production

Question 11

What are the symptoms associated with acute aflatoxin poisoning in animals?

Answer 11

liver necrosis and hemorrhage, weakness, vomiting, loss of appetite

Question 12

How is acute aflatoxin poisoning diagnosed?

Answer 12

increased liver enzymes like alkaline phosphatase, AST or ALT, bilirubin and serum bile acids

Question 13

What are the results of chronic aflatoxin poisoning?

Answer 13

liver fibrosis, cirrhosis, tumors, bile duct hyperplasia

Question 14

What are the symptoms present in humans after inhalation and ingestion of aflatoxin?

Answer 14

Inhalation-cough, fever, chest pain, hemoptysis
Ingestion-liver damage or cancer

Question 15

What species produce ochratoxin?

Answer 15

Penicillium verrucosum and aspergillus molds

Question 16

Where is it found in ?

Answer 16

cereal grains, red wine, coffee beans

Question 17

What is the most toxic ochratoxin and its MOA?

Answer 17

Ochratoxin A and it competes with phenylalanine in the process of phenylalanyl-tRNA synthesis, or inhibits other enzymes like phenylalanine hydroxylase, inhibits protein synthesis

Question 18

What are the symptoms of ochratoxin poisoning in humans?

Answer 18

fatigue, chronic pain, GI symptoms, autoimmune, insomnia

Question 19

What are the symptoms of ochratoxin poisoning in animals?

Answer 19

feed refusal, vomiting, diarrhea and anorexia

Question 20

What occurs in high vs low does of ochratoxin

Answer 20

high does: kidney damage, low: carcinogenicity and also possibly teratogenic

Question 21

What are the fusarium toxins discussed in class?

Answer 21

T2, Deoxynivalenol. fumonisins and zearalenone

Question 22

What are the species that produce T2 toxin?

Answer 22

fusarium poae, fusarium sporotrichioides and fusarium tricinctum (mainly)

Question 23

What are the physical and structural properties of T2?

Answer 23

non-volatile, low molecular weight sesquiterpenoids

Question 24

What is the LD50 of T2 in mice?

Answer 24

2-4mg/kg

Question 25

What is T2's MOA?

Answer 25

Targeting 60S ribosomal subunit which inhibits protein synthesis leading to apoptosis

Question 26

What are humans symptoms after being exposed to T2?

Answer 26

vomiting, stomach necrosis, hemorrhage and dermatitis

Question 27

What are the symptoms present in animals after T2 poisoning?

Answer 27

feed refusal, vomiting, stomach necrosis

Question 28

What is alimentary toxic aleukia?

Answer 28

leukopenia, agranulocytosis, nectroic angina, sepsis all caused by T2 poisoning-occurred in families in the USSR

Question 29

What is Vomitoxin and its LD50?

Answer 29

trichothecene mycotoxin, 50-100mg/kg

Question 30

What is DON's MOA?

Answer 30

halts protein synthesis by binding to ribosome and activate MAPks ribotoxic stress response causing inflammation (chemokines, cytokines) in low doses or apoptosis in high doses

Question 31

What are the symptoms of DON toxicity in humans?

Answer 31

nausea, vomiting and diarrhea

Question 32

What are the symptoms of DON toxicity in animals?

Answer 32

diarrhea and vomiting (pigs)

Question 33

What animals are most sensitive to DONS?

Answer 33

pigs, rats and mice

Question 34

Why do we puke when exposed to DON?

Answer 34

damage to enterochromaffin cells, releases serotonin, vagal afferent nerve sends signal to vomit center and posterma in brainstem detects toxin in blood, further amplifying nausea and vomiting signals

Question 35

What are the symptoms of acute intoxication of fumonisin?

Answer 35

GI

Question 36

What are the symptoms of chronic intoxication of fumonisin?

Answer 36

cancer of GI (esophagus), neural tube defects and transfer to breast milk

Question 37

What is equine leukoencephalomalacia?

Answer 37

disease of the CNS that comes from horses, mules and donkey's eating moldy corn. White matter liquefies- symptoms: drowsiness, apathy, blindness, circling, stumbling, recumbency and pharyngeal paralysis, 8-10ppm

Question 38

What is porcine pulmonary edema?

Answer 38

fluid leakage into lungs in pigs, symptoms: dyspnea, cyanosis of mucous membranes, weakness and recumbency, occurs 3-6 after consumption of fumonisins of >100ppm

Question 39

What organisms produce Zeralenone?

Answer 39

F. gra,omearum, F. culmorum, F. cerealis, F. equseti, F. crookwellense, etc.

Question 40

Where is Zeralenone typically found?

Answer 40

in warmer climates?

Question 41

What is Zeralenone's MOA?

Answer 41

binds and activates estrogen receptors, 2-4 times less potent agonist than estradiol

Question 42

Why is Zeralenone carcinogenic?

Answer 42

affects apoptosis, DNA fragmentation and adduct formation, alters DNA repair mechanisms and could induce cancer cell proliferation

Question 43

What species produced ergot toxin and what does it infect?

Answer 43

clavicep purpurea-infects cereal grains

Question 44

What are the three different types of ergot alkaloids?

Answer 44

amine: uterotonic effects peptide: ergocristine and ergotamine, vasconstrictive clavine: simpler alkaloids

Question 45

What are symptoms of ergot poisoning?

Answer 45

hallucinations, severe gastrointestinal distress, convulsion and gangrene