BIOL 0510 - Fungi

Fungi are involved in the manufacturing of which foods?

bread, some cheeses and alcoholic beverages

Which drugs have fungi helped make?

Penicillin, cyclosporin and cephalosporin

Can fungi be parasitic?

yes, in animals

What’s fungi’s main role?

decomposing dead organisms and recycling nutrients

How many phyla are within the fungi kingdom?

5

How did ancient Egyptians use fungi?

they rubbed moldy bread on wounds

What is yeast?

small round unicellular fungi

What is mold?

long branched filaments called hyphae

What does it mean if a fungus is dimorphic?

it can grow as both yeast and mold-like cells

Many yeasts are…

ascomycetes

How do most yeast reproduce?

budding

Why is S. cerevisiae a model eukaryote?

the genes controlling it’s cell cycle are similar to human ones and it uses asexual and sexual modes of reproduction

What did Dr. Paul Nurse win a Nobel Prize for?

Identifying genes that play a role in the cell cycle using S. pombe and found that cell length directly correlated with phases of the cell cycle

What can bud scars be used to determine?

number of divisions yeast cells have undergone

What’s are some of the more complex ways that fungi can divide?

dendritic colonies and multi-budding

Fungi are heterotrophi meaning that…

they feed on preformed organic material

How do fungi “eat”?

produce and secrete hydrolytic enzymes to break up organic material then absorb the digested material

What are saprobes?

Eat decaying and non-living material

What are mutualists?

Fungi that live in association with the host without harming it (and often helping it).

Which organism may be the largest organism on earth?

Armillaria because it spreads over 1000s of acres and several feet deep and it has a total mass larger than a blue whale

Can the cells in mold contain more than one nucleus?

yes and sometimes hundreds

Give exampels of common molds?

Rhizopus (on strawberries) and Asperillgus (black mold in homes)

What makes mold hard to get rid of?

aerial hypha form conidia (asexual spores)

How can mold spores affect health?

Cause respiratory problems

What are basidiomycetes?

mushrooms - filamentous fungi that form fruiting bodies

What do basidiomycetes release?

sexual spores from the underside of the cap that get dispersed by the wind and lead to spore germination elsewhere

What is the active compund of magic mushrooms?

Psilocybin

What is the effect of psilocybin?

it influences serotonin receptors and can cause hallucinations but it could also be used to treat PTSD and depression

What percentage of mushrooms are poisonous?

approximately 50%

What are mycorrhizae?

fungal associations with roots

What do mycorrhizal fungi do?

obtain carbon from root secretions and inorganic material e.g nitrogen from the soil

What do mycorrhizal plants do?

obtain more nutrients from the soil due to greater surface area from fungal filamentous cells

Are mycorrhizae inside or outside of a plant?

both

What’s an example of mycorrhizal fungi?

truffles and they are found in close association with the roots of trees

What are some fungal phyla that are considered mycorrhizae?

Zygomycetes, Glomeromycetes, Ascomycetes, Basiomycetes

Provide examples of plant fungal pathogens?

dutch elm disease, corn smut and rice blast

Which fungus causes rice blast?

magnaporthe oryzae

What is the effect of Magnaporhte oryzae infection on rice plants?

it forms a structure called the appressorium which generates lots of cellular turgor which ruptures the plant cuticle

What are chytrids?

a fungi that’s been killing lots of amphibian species and even causing extinction

What does Bd (a chyrid) do to amphibians?

infect the outer skin and cause it to slough off which is detrimental to amphibians because they breath through their skin

What makes Bd unique?

it can swim and its spores swim towards frogs and burrow in their skin

How can frogs be protected from Bd fungus?

hotspot shelters with a higher temperature that isn’t favourable for the fungus

What is P. destructans?

an ascomycete associated with bat “White-Nose Syndrome”

What kind of bats is White Nose Syndrome found on?

hibernating bats because their temperature is around 14 degrees which is ideal for the fungus

What is the effect of WNS on bats?

the fungus wakes them up from hibernation early before there are enough insects for them to eat so they die from starvation

Why are bats beneficial animals?

They eat lots of insects and basically act as pest control. They also pollinate plants

What are dermatophytes?

human pathogenic fungi that are contagious and live in dead layers of the skin

What are examples of dermatophytes?

ringworm, dandruff and Athlete’s foot

Most pathogenic fungi are…

opportunistic pathogens

How many known fungi are true human pathogens?

4

The four true human fungi pathogens are…

dimorphic and their growing form is dependent on temperature

What is a pathobiont?

an organism that lives in association with others but don’t derive their nutrition from them

What can Candida cause?

thrush and mucosal and bloodstream infections

Why does Candida normally cause infections in immunocompromised individuals?

it’s part of the normal microbial flora or humans and is found in the GI tract

How does Candida kill macrophages?

by growing hyphae and bursting out of macrophages after ingestion

Why are Candida infections difficult to treat?

they form biofilms

What does Candida albicans release?

a toxin called Ece1 (Candidalysin) that generates pores in host cells and enables gut colonisation

Where does Candida like to grow?

on implants in the human body

When does disease occur?

when the immune response is too weak or too strong (immunopathology)

What is believed to have occured after the large asteroid hit the earth 65 million years ago?

Asteroid caused low sunlight, leading to decay and cooler temperature for years. This promoted a fungal bloom and cold-blooded reptiles got fungal infections

Why didin’t reptiles recover after the asteroid?

cold blooded animals are more susceptible to fungal infections than mammals because mammanlian body temperature is around 37 degress celsius

Which fungus is responsible for zombie insects?

Cordyceps