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Aflatoxins are produced by strains of Aspergillus niger.
Aflatoxins are produced by strains of Aspergillus niger.
False
The term 'aflatoxin' is derived from the species Aspergillus flavus.
The term 'aflatoxin' is derived from the species Aspergillus flavus.
True
Aflatoxins were first isolated in Brazil.
Aflatoxins were first isolated in Brazil.
False
Aflatoxins are commonly found in aquatic environments.
Aflatoxins are commonly found in aquatic environments.
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Aspergillus flavus has both sexual and asexual forms of reproduction.
Aspergillus flavus has both sexual and asexual forms of reproduction.
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Asexual reproduction in Aspergillus flavus produces sclerotia.
Asexual reproduction in Aspergillus flavus produces sclerotia.
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Contamination by aflatoxins can occur pre-harvest and post-harvest.
Contamination by aflatoxins can occur pre-harvest and post-harvest.
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The hyphal growth of Aspergillus flavus typically forms a spiral structure.
The hyphal growth of Aspergillus flavus typically forms a spiral structure.
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Aflatoxins are unstable compounds that are easily destroyed during normal food processing.
Aflatoxins are unstable compounds that are easily destroyed during normal food processing.
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Aflatoxin B1 is considered the least toxic compound among aflatoxins.
Aflatoxin B1 is considered the least toxic compound among aflatoxins.
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Aflatoxin G1 and G2 exhibit blue fluorescence under UV light.
Aflatoxin G1 and G2 exhibit blue fluorescence under UV light.
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Aflatoxins can be transmitted to humans through contaminated animal products.
Aflatoxins can be transmitted to humans through contaminated animal products.
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The TD50 for aflatoxins is a measure of their carcinogenic potency.
The TD50 for aflatoxins is a measure of their carcinogenic potency.
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Aflatoxin M2 is a metabolite derived from aflatoxin G2.
Aflatoxin M2 is a metabolite derived from aflatoxin G2.
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The furan ring in aflatoxins is a key site for its toxic activity.
The furan ring in aflatoxins is a key site for its toxic activity.
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Aflatoxins can cause significant mutagenesis even in metabolized forms.
Aflatoxins can cause significant mutagenesis even in metabolized forms.
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Aflatoxins are primarily known for causing respiratory diseases.
Aflatoxins are primarily known for causing respiratory diseases.
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Aflatoxin B1 is classified as a group I carcinogen by WHO.
Aflatoxin B1 is classified as a group I carcinogen by WHO.
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All animals have the same susceptibility to aflatoxins.
All animals have the same susceptibility to aflatoxins.
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Chronic exposure to aflatoxins can lead to immune suppression.
Chronic exposure to aflatoxins can lead to immune suppression.
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The maximum safe level of aflatoxins for human consumption is 200 ppb.
The maximum safe level of aflatoxins for human consumption is 200 ppb.
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Aflatoxins have been linked to outbreaks causing fatalities in East Africa.
Aflatoxins have been linked to outbreaks causing fatalities in East Africa.
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Children exposed to aflatoxins may experience accelerated growth.
Children exposed to aflatoxins may experience accelerated growth.
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Loss in animal wealth is a consequence of aflatoxin contamination.
Loss in animal wealth is a consequence of aflatoxin contamination.
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Aflatoxins do not require bioactivation to exhibit toxicity.
Aflatoxins do not require bioactivation to exhibit toxicity.
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The transversion caused by aflatoxin B1-DNA adducts involves a change from a one-ring pyrimidine to a two-ring purine.
The transversion caused by aflatoxin B1-DNA adducts involves a change from a one-ring pyrimidine to a two-ring purine.
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Insect management is a pre-harvest prevention strategy to minimize aflatoxin formation.
Insect management is a pre-harvest prevention strategy to minimize aflatoxin formation.
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Glutathione S-transferase enzymes help in neutralizing the active epoxide form of aflatoxins.
Glutathione S-transferase enzymes help in neutralizing the active epoxide form of aflatoxins.
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Proper food storage does not significantly contribute to preventing aflatoxin contamination.
Proper food storage does not significantly contribute to preventing aflatoxin contamination.
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Thermal processing over 100ºC can effectively detoxify aflatoxins if done in wet conditions.
Thermal processing over 100ºC can effectively detoxify aflatoxins if done in wet conditions.
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Harvesting ripe crops quickly can contribute to the prevention of aflatoxin formation.
Harvesting ripe crops quickly can contribute to the prevention of aflatoxin formation.
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Decontamination strategies include physical separation and fermentation of contaminated grains.
Decontamination strategies include physical separation and fermentation of contaminated grains.
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Study Notes
Aflatoxins
- Producing organisms: Aflatoxins are fungal secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. These fungi are saprotrophic and pathogenic.
- Morphology: Aspergillus flavus has a broom-like shape, consisting of hyphae, conidia, and sclerotia. Hyphal growth occurs by branching and produces mycelia.
- Reproduction: Aspergillus flavus reproduces both sexually and asexually. Asexual reproduction produces conidia (spores) and sclerotia. Sexual reproduction produces sclerotia. The color of conidia varies by colony age: yellow-green for young and dark green for old colonies.
- Exposure methods: Aflatoxins contaminate food and feed through pre-harvest and post-harvest processes, and are often found in peanuts, cottonseed meal, corn, and other grains. Humans can be exposed through direct contact with the fungus or by consuming contaminated foods or animal products.
- Chemical structure: Aflatoxins are highly stable compounds, withstanding normal food processing procedures. They have a low molecular weight (312 Da), composed of three parts: a coumarin nucleus, a lactone ring, and a furan ring. The furan ring is the key active site for its toxic and carcinogenic properties.
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Major types: There are four major types of Aflatoxins:
- Aflatoxin B1 and B2 (AFB): Produce blue fluorescence under UV light on Thin Layer Chromatography (TLC). They are produced by both Aspergillus flavus and Aspergillus parasiticus.
- Aflatoxin G1 and G2 (AFG): Produce green fluorescence under UV light on TLC. They are produced by some group II strains of Aspergillus flavus and Aspergillus parasiticus.
- Toxicity: Aflatoxins exert toxic effects on humans and animals. Aflatoxin B1 is considered the most toxic and is classified as a Group 1 carcinogen by the World Health Organization (WHO).
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Symptoms: Symptoms of acute aflatoxicosis include:
- High fever
- Progressive jaundice
- Weakness
- Tachycardia
- Edema
- Nausea
- Headache
- Rash
- Ascites
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Health impact: Aflatoxins cause a range of health problems including:
- Liver cancer
- Immune suppression
- Slow growth and underweight in children
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Economic impact: Aflatoxin contamination affects the economy through:
- Healthcare and treatment costs
- Loss of animal wealth
- Cost of monitoring and management programs
- Metabolism and Toxicity Mechanisms: Aflatoxin B1 undergoes bioactivation inside the target organism, transforming from a bio-inactive form to a reactive 8,9-epoxide form.
- Epoxide formation: The epoxide form binds to both DNA and proteins via cytochrome P450 enzymes, forming adducts. Aflatoxin B1-DNA adducts can result in GC to TA transversions, leading to loss of cellular control.
- Glutathione S-transferase system: The enzyme system of glutathione S-transferase can neutralize the active epoxide form.
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Protection Strategies:
- Pre-harvest prevention: Utilize resistant varieties (if applicable), improve farming practices (crop rotation, irrigation, insect management), harvest crops quickly, and minimize kernel damage during harvesting.
- Post-harvest prevention: Clean and dry corn to less than 15% moisture, store crops properly with temperature-moisture control, separate animal feed, and manage insects and pests.
- Decontamination and Detoxification: Includes physical separation, food/feed processing (fermentation, thermal processing), and diversion to industrial uses under strict precautions, control, and monitoring processes.
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Description
This quiz explores the characteristics and implications of aflatoxins, focusing on the fungal organisms that produce them, primarily Aspergillus flavus and Aspergillus parasiticus. It covers their morphology, reproduction, and the methods of exposure to humans through contaminated food and feed sources.
