Chytridiomycota

Question 1

Chytridiomycosis

Answer 1

• first described in 1988
• a disease of amphibians caused by the fungus Batrachochytrium dendrobatidis
• thought to be a major cause of global amphibian decline

Question 2

symptoms of chytridiomycosis

Answer 2

• abnormal posture
• lethargy
• loss of righting reflex
• gross lesions and epidermal ulcerations
• skin hemorrages

Question 3

Chytridiomycosis diagnosis

Answer 3

• intracellular flask-shaped sporangia within epidermis
• occurrence only in keratinized tissue suggests keratin as nutrient
• Batrachochytrium dendrobatidis - new genus & spp

Question 4

Koch’s postulates

Answer 4

• a sequence of experimental steps for directly relating a specific microbe to a specific disease
• isolate into pure culture
• re-inoculation into healthy host
• re-culture

Question 5

Chytrid mortality mechanisms

Answer 5

• fungus impairs essential cutaneous respiration or osmoregulation
• fungus produce mycotoxin that is absorbed systemically

Question 6

Emergence of chytridiomycosis

Answer 6

• surveys suggests the disease emerged on 2 continents at same time
• prefers high altitudes - lower temps
• damaging in australia and central america (costa rica)

Question 7

Amphibian IUCN red list

Answer 7

• 41% of all extant amphibian species at risk

- chytridiomycosis is the worst infectious disease recorded among verts in terms of spp inpacted

Question 8

Chytridiomycosis and international trade

Answer 8

• trade of African clawed frog and American bullfrog may have facilitated dispersal of pathogen between continents
• for bullfrog, over 20 million specimens traded in 8 years
• bullfrog is a carrier but does not get infected

Question 9

What amphibian was strongly impacted by chytridiomycosis

Answer 9

• golden toad

- went extinct in 1989