Fungus-Animal Interactions Flashcards
What is an allergy?
Hypersensitivity to fungal antigens such as inhaled fungal spores.
What is mycotoxicoses?
Ingestion of fungal toxins in contaminated food or poisonous mushrooms.
What are mycoses?
Fungi invading living animal tissue.
What are the different levels of fungal infection in humans?
Superficial, cutaneous, subcutaneous, systemic (dimorphic) or systemic (opportunistic).
What fungus causes amphibian chytridiomycosis?
Batrachochytrium dendrobatidis (Bd).
What is driving the spread of Bd in amphibians?
Changing climate as well as the amphibian pet trade.
How does Bd infect amphibians?
Spores land on the amphibians and penetrate the skin.
How does Bd kill infected individuals?
The spores increase the no. of cells produced leading to skin thickening. This prevents electrolyte transport as well as ventilation leading to death.
What are oomycetes?
AKA water moulds, they are fungus-like eukaryotic microorganisms. As parasites they are commonest on fish.
How do spores remain in contact with the host?
They may have mucilaginous coats, slime drops or host specific adhesive secretions.
How can fungi infect animals?
Penetrate the cuticle.
Penetrate arthrodial membrane between joints/segments.
Via sense organs/gut.
How do fungi penetrate the surface of animals?
Using both enzymes and mechanical pressure.
How do fungi spread within a host?
Using dispersal structures such as blastospores or hyphal fragments.
What are some host defences against fungal infection?
Phagocytosis, haemolytic encapsulation and humoral encapsulation.
Define haemolytic encapsulation.
Haemocytes accumulate around a fungal infection to form a capsule.
Define humoral encapsulation.
The deposition of melanin-protein complex on the surface of the fungus.
What toxins are produced by infecting fungi?
Destruxins and toxic proteases.
What is the main cause of death in animals infected by a fungus?
Chronic disruption of host physiology as a result of mycelial development.
What part of invertebrates is first invaded by the fungus?
The haemocoel.
What is “summit disease”?
A behavioural change caused by a number of fungi whereby the host climbs to the top of a plant to die. This ensures the fungal spores disperse far.
What are some methods of exiting the host?
Mechanically when insects fly over.
Forcibly discharging from the host.
Attraction of an uninfected host.
