Mycotoxins Flashcards
What are mycotoxins
Highly toxic secondary metabolites produced by fungi
What are primary metabolites
Produced by all fungi as a result of normal nutrient metabolism, role in growth and development
What are secondary metabolites
Not produced by all fungi, may function to establish an environmental niche against competing microbes
Conditions for mycotoxin production
Having the specific gene and then specific environmental conditions which cause the gene to be expressed to lead to toxin being produced
Can mycotoxins form pre and post harvet
Yes
What is optimal moisture and why important
Over 13% and is most important factor in mold growth
What are aflatoxins from
Aspergillus flavus
Mechanism of toxicity from aflatoxins
Damage liver because aflatoxin is activated in liver to form a metabolite (epoxide) which is an oxidizing agent The epoxide binds to DNA and causes damage
What is more sensitive to aflatoxins
Younger animals and monogastrics specifically birds and fish which can accumulate it over time and develop liver cancer
What defines acute toxicity of aflatoxicosis
Large amount aflatoxin ingested in short time and causes clinical signs- bloody diarrhea and liver damage within hours or days
What defines chronic toxicity of aflatoxicosis
Prolonged ingestion of lower amounts of the toxin causing decreased growth and liver cancer
Diagnosis of aflatoxicosis
Submit feed to lab for quantitative analysis
Treatment of aflatoxicosis
No antidote, just supportive care
Zearalenone is produced by
Fusarium species
Zearalenone Mimics
Estrogen
Zearalenone Affects what
Gilts
Zearalenone Toxicosis is causes
Premature sexual development or pseudo-pregnancy, low fertility, or reduce reproductive efficiency in boars
Trichromaticthecenes do what
Inhibit protein synthesis by binding to ribosomes
Vomitoxin causes what in what
Severe gastroenteritis with vomiting and diarrhea in pigs
Vomitoxin treatment
Remove feed and check feed for others because Vomitoxin is indicator of other mycotoxins
Fumonisins are toxic to what in body
hepatotoxic (liver), neurotoxic (nervous system), and carcinogenic to humans
Fumonisin mechanism of action
Blocks enzymes involved production in intermediate lipid creamide of the sphingolipid (interferes with biosynthesis) in the cell membranes of liver and nerve cells
What are signs of Equine Leukoencephalomalacia as a result of fumonisin toxicity aka moldy corn poisoning
Blindness, circling, staggering, seizures in horses (ruminants and poultry resistant)
Ergot toxins are produced by
Claviceps purpurea
Ergot fungi (C. purpurea) prefer what
Warm/wet growing seasons which favors alkaloid production
C. Purpurea forms what
A sclerotia which is a structure following the germination of the fungal spore on rye, wheat, oats and others
Ergotism clinical disease effects what mostly
Everything but animals that graze are mostly likely exposed, especially cattle
What do Alkaloids do to cause symptoms of Ergotism
Cause vasoconstriction of arterioles to reduce blood flow to extremities- lameness is an early sign
Other signs are peripheral tissue sloughing on tail, ears, and limbs in winter months
Diagnosis and treatment of ergotism
Finding sclerotia in pastures or grain and need to remove food or animals from pasture, rotating crops can reduce incidence- only survives in environment for a year
Mycotoxin detection requires what
To identify mycotoxin so sampling is critical and immunoassays (ELISA) will provide a rapid diagnosis
How to manage mycotoxin in feed
Limit moisture post harvest, dispose of contaminated feed by burning or blend bad feed with clean feed or feed to non-susceptible species or add chelators to feed to bind toxins
What is sensitive to Trichothecenes
all animal species
Trichothecenes most prevalent mycotoxin is what
vomitoxin
What animals are most sensitive to fumonisin
Horses and swine
What produces fumonisin
Fusarium moniliforme
