Mycology & Bacterial Pathogenesis MIMM 211 Final

Eukaryotic with a nucleus

What are fungi classified as?

Composed of chitin → NOT cellulose/lignin like plants

What are fungi cell walls composed of?

Reproduction by spore formation → can be asexual (mitosis) or sexual (meiosis) → disseminated by wind

How do fungi reproduce?

Can be multicellular (form thread-like filaments → hyphae) or unicellular (yeast)

Are fungi multicellular?

They are heterotrophic → obtain nutrients by secreting enzymes that break down complex chemicals into simple components that can be absorbed

How do fungi get nutrients?

Mostly nonmotile

What’s fungi motility?

The fungal body of a large single cell

What is a thallus?

Filamentous tubular structure with internal septa and multiple nuclei (in multicellular fungi)

What are hyphae?

Cross-walls in hyphae (create compartments with pores so cytoplasm can flow through)

What are septa?

Hyphae that contain cross-walls

What are septate hyphae?

Hyphae that do not contain septa

What are coenocytic hyphae (aseptate)?

Groups/mass of hyphae, often used interchangeably with hyphae

What are mycelium?

Vegetative obtain nutrients while aerial are involved with asexual reporoduction

Vegetative hyphae vs aerial hyphae?

Hyphae that extend above the surface produce spores called conidia → they are pigmented and resistant to drying

What are conidia?

Non-filamentous, unicellular fungi that are typically oval or spherical

What’s the morphology of yeast?

Asexual reproduction → Divide evenly to produce 2 new cells

What are fission yeast?

Asexual reproduction → Divide unevenly

What’s budding yeast?

Some yeast produce buds that fail to detatch themselves

What are pseudohypha?

Multicellular fungi that grow in hyphae

What is mold?

Fungi can grow as mold (25oC) or as yeast (37oC) → moldlike form produce vegetative and aerial hyphae and yeastlike reproduce via budding

What are the 2 dimorphisms of fungi?

Biodegradation, industrial reproduction, food industry

What are the good traits of fungi?

Infection, intoxication, allergy, degradation

What are the bad traits of fungi?

Closer to animals than plants

Are fungi closer to animals or plants on the phylogenetic tree of life?

Non-motile → digest and absorb rather than absorb and digest → have ergosterol not cholesterol in their membranes → asexual reproduction → nucleus is small w/ repetitive DNA

How do fungi differ from animals?

Cell wall made of chitin not lignin/cellulose → no photosynthesis or chloroplasts → no vascular structures → make glycogen as a storage carbohydrate

How do fungi differ from plants?

On their sexual cycle → fungi comprise 6 major phyla → most belong to ascomycota and basidiomycota

How are fungi classified?

Large and diverse group of fungi that includes yeast (saccharomyces) and mold (aspergillus)

What is ascomycota?

Include fungi that form mushrooms

What is basidiomycota?

Via the formation of spores that detach from the parent and germinate into a new mold

How do fungi reproduce sexually and asexually?

Anamorph

What is the asexual form of fungi?

Teleomorph

What is the sexual form of fungi?

Homothallic (mating occurs between hyphae of same mating type (loci region) or same thallus) → heterotrophic → heterothallic (mating occurs between two different thalli or mating types)

What are the 2 types of sexual reproduction?

Formed by hyphae of one organism → identical to the parent → produced by an individual fungus through mitosis and cell division

How are asexual spores formed?

Asexual spore → Not enclosed in a sac

What’s a conidiospore?

Asexual spore → Fragmentation of septate hyphae

What’s an arthroconidia?

Asexual spore → Buds of the parent cell

What’s a blastoconidia?

Asexual spore → Spore with a hyphal segment

What’s a chlamydoconidium?

Asexual spore → Enclosed in a sac

What’s a sporangiospore?

Fusion of nuclei from 2 mating strain

How are sexual spored formed?

Plasmogamy (haploid donor cell nucleus (+) penetrates cytoplasm of recipient cell (-) → karyogamy (+ and - nuclei fuse and form diploid zygote → meiosis (diploid nucleus produces haploid nuclei (sexual spores)

→ type of sexual spored varies by phylum!!

What are the 3 phases of sexual reproduction?

Good : Produce progeny more fit for the environment → purge the genome of deleterious mutations → Bad: energy/time required to find a partner → you could break apart valuable genetic combinations

Advantages and disadvantages of sexual reproduction?

Motile (only chytrid fungi are motile) → insect and animal vectors (cordyceps, zygomycetes) → passive and cooperatively generated wind → active dispersal structures: basidiomycetes)

How do spored get dispersed?

Duplication through binary fission or mitosis (budding yeast)

Asexual reproduction traits (anamorph)?

Arthrospores or arthroconidia: fragmentation of septate hyphae

Conidiospores (ascomycetes): not enclosed in a sac

Sporangiospores (zygomycetes): enclosed in a sac

Chlamydospores: within a hyphal segment

Blastoconidia: buds off the parent cell

What are the types of spores in asexual reproduction?

Spores vary by phyla/genus:

• Ascospores (ascomycetes)

• Basidiospores (basidiomycetes)

• Zygospores (zygomycetes)

• Zoospores (chytrids)

What are the different spores for sexual fungi (teleomorph)?

Microsporidia (d.c), Chytridiomycota, Mucoromycota (d.c), Glomeromycota, Ascomycota (d.c), and Basidiomycota (d.c)

What is the phylogeny of fungi?

Earliest diverging lines of fungi, key genus: encephalitozoon, asexual reproduction, obligate parasites (evolved to be as simple as possible), causes chronic debilitating diseases of the intestine, lung, eye, muscle (mostly in immunosuppressant people, AIDS)

What are microsporidia?

Spores inhaled, spore injects tube into host cell, cytoplasm and nucleus enter, cytoplasm grows and nuclei reproduce, cytoplasm breaks up around nuclei to form spores, new spores are released

What is the life cycle of encephalitozoon?

Earliest fugal lineage, found in moist soil & freshwater, asexual and sexual spores, batrachochytrium (die-off of amphibians (largest mass extinction since asteroid hit dinosaurs), chytridomycosis: infection of epidermal layers)

What are chytridiomycota?

Key genus: zygomycota, known for food spoilage, found in soil and decaying plant material, coenocytic hyphae (aseptate), produced sexually: sporangiospore, produced sexually: zygospore, rhizopus is species that can cause serious infection of the lung, sinuses, eyes, nose and mouth

What is mucromycota?

Aerial hypha produces a sporangium, sporangium bursts to release spores, spores germinate to produce hyphae, vegetative myselium grows, gametes form at tip of hypha, plasmogamy, zygospore forms, karyogamy and meiosis, zygote produces a sporangium, spores are released and form sporangium, spore germinates to produce hyphae

What’s the life cycle of rhizopus?

Zygomycete that grows in cow dung, spores passaged through dung, uses hydrostatic cannon guided by light to shoot spores into unsoiled grass (active dispersal),

What is pilobolus?

Small group pf fungi w/ ecological importance, all known species form endomycorrhizae (fungal hyphae enter plant cells & aid the plant get phosphatefrom soil in return for fixed carbon from the plant), only asexual reproduction, mostly coencocytic (aseptate) hyphal morphology

What is glomeromycota?

Key genera: saccharomyces, candida, aspergillus, medically important, ranges from baker’s yeast to common molds, sac fungi, septate hyphae, produce asexually: conidiospores and sexually: ascospore, asci (2 haploid nuclei from different mating types fuse to form a diploid nucleus that undergoes meiosis to form haploid ascospores)

What are ascomycota?

Cup fungi (shotgun), flask fungi (rifle), and grenade

What are the various ways that ascocarops disseminate the asci?

Hypha produces conidiophore, conidia are released from conidiophore, conidium germinates to produce hyphae, vegetative mycelium grows, plasmogamy, karyogamy, meiosis then mitosis, ascus opens to release ascospores, ascospore germinates to produce hyphae

What is the ascomyetes life cycle?

Cells are spherical to oval, asexual cell division happens through budding and sexual reproduction happens though mating (ascospores are formed), flourish in sugar habitats, they don’t only undergo sexual reproduction, may just go asexual route

How does reproduction in saccharomyces cerevisiae work? (yeast reproduction)

Pseudogymnoascus destructans, infects bats while hibernating, bats were dying and not eating insects, insects are vectors for bacteria and viruses

What is white nose syndrome?

Only phylum that makes classic mushrooms, septate hyphae, commercial & poison mushrooms (agaricus and amanitus), produced asexually (conidiospores) and sexually (basidiospores)

What is basidiomycota?

Basidiospores are formed externally on a base pedestal called a basidium (structure on which haploid basidiospores are formed by meiosis), sexual reproduction phase is the mushroom structure, increases dispersion by increasing surface area and elevation

How does sexual reproduction work in basidiomycota?

Hyphal fragment breaks off vegetative mycelium, fragment grows to produce new mycelium, vegetative mycelium grows, plasmogamy, fruiting structure develops (mushroom), basidiospores are formed by meiosis, basidiospores mature, basidiospores are discharged, basidiospores germinate to produce hyphae

What is the basidiomycota life cycle?

Buller’s drop swells until eventually it contacts the spore water drop, sudden flow of water onto the spore in arrested by surface tension, this knocks the spore away from the sterigma

How does surface tension catapult work as an active dispersion method?

Spore ejection from external force,

What is the puffball fungi basidiospore dispersal strategy?

Basidiomycete, bright orange pigment, glows in the dark due to luciferase production, poisonous to humans

What is omphalotus olearius? (Jack-O-Lantern mushroom)

Spores are haploid but fungi spend their time a diploids during the sexual reproduction cycle

Are fungi haploid or diploid?

Inappropriate immune responses, infections, mycotoxins

How do fungi cause disease?

Evoke IgE hypersensitivity response w/ mast cell degranulation and histamine release → aspergillius

Why do fungi cause hypersensitivity?

Uncomplicated asthma is due to sensitization to conidial antigens of aspergillus, controllable w/ medicine

How is asthma caused?

Lung disease that occurs in some people allergic to Aspergillus → lethal to immunocompromised people

What is allergic bronchopulmonary aspergillosis?

Decomposing hay has thermophilic bacteria and fungi → acute hypersensitivity pneumonia from massive antigen inhalation

What is aspergillus allergic disease? (Farmer’s lung)

Fungal infection of the body

What is mycosis?

What are the 2 extremes of fungal infections?

Superficial and systemic

What is superficial mycoses?

Common, benign, can infect immunocompetent

What is subcutaneous mycoses?

Affect deeper layers of skin than those of the superficial mycoses

What’s systemic mycoses?

Less common, affects all systems in body, lethal to immunocompromised people usually lethal if untreated

What causes superficial mycoses?

Caused by dermatophytes of the Ascomycota phylum, infect only the surface layers (hair, skin, nails), Trichophyton cause infections of the feel (athlete’s foot), informally known as ringworm or tineas, can be treated with antifungal cream

What causes subcutaneous mycoses?

Fungi enters through deep wounds, caused by fungi that inhabit the soil

What is sporotrichosis disease?

Caused by Sporothrix schenkii, dimorphic fungus, also Ascomycota, entera a wound, forms a small ulcer

What causes systemic mycoses?

Live in soil, mainly yeast and dimorphic fungi, humans become infected by inhailing spores

What is histoplasmosis caused by?

Histoplasma capsulatum

What is blastomycosis caused by?

Blastomyces dermatitidis

What is cryptococcosis caused by?

Cryptococcus neoformans

What is Candidiasis caused by?

Candida species

What are factors that can increase the severity of a fungal infection?

Taking immunosuppressive drugs, pregnancy, antibiotic use

What are the types of systemic fungal diseases?

Yeasts, dimorphic fungi, and molds

What is Candidiasis?

Over growth of Candida albicans (yeast), forms pseudohyphae making it resistant to phagocytosis, occurs in the skin and mucous membranes of the genitourinary tract and mough, Thrush → C. albicans infection of the oral cavity

When are you vulnerable to C. albicans?

Antibiotics suppress competing bacteria or a change occurs in the mucosal pH

What is Candida albicans?

Grows as yeast (pseudohyphae), morphological switch in important for virulence (either can be pseudohyphae or they can start budding), they live in the gut so if there’s a breech in the lining they can enter → they sexual cycle involves diploid fungi combining to form tetraploids then chromosomes shed overtime to return to diploid

What is Candida auris?

First isolated in Japan, skin colonizer but also bloodstream, ear, lungs, multi-drug resistant

What is cryptococcus?

Encapsulated yeast, sexual cycle (masidiomycete and heterothallic), two common speices (neoformans and gatti), found in soil, associated with bird droppings or in eucalyptus trees

How does infection with cryptococcus happen?

Inhalation of yeast spores or basidiospores, initial asymptomatic pulmonary infection with dissemination → C. neoformans often present as chronic meningitis, mist cases associated with immune deficiency

What are virulence factors?

Capsule (inhibits phagocytosis), thermotolerance (permits growth in CSF0, melanin (anti-oxidant, resists phagocyte killing)

What is cryptococcus gatti?

First seen in marine animals in Vancouver, pneumonia and meningitis in immunocompetent patients, infecting native trees and soil

What are dimorphic fungi?

Grow as mold in soil and then as yeast in humans, primary fungal pathogens (infect immune normal individuals), classically dimorphic (histoplasma capsulatum, coccidioides immitis, and bastomyces dermatiditis)

What is histoplasmosis?

Caused by Histoplasma capsulatum, dimorphic fungus, yeast-form grows intracellularly in macrophages, forms lung lesions, acquired from airborne conidia in areas with bird or bat droppings

What is coccidioidomycosis?

Caused by Coccidioides immitis, dimorphic fungus, found in alkaline desert soil, most infections have fever, cough and weight loss

What is blastomycosis?

Caused by blastomyces dermatitidis, dimorphic fungus, grows on soil, symptoms resemble bacterial pneumonia cutaneous abscesses, extensive tissue damage, associated w/ rotting wood, dissemination through skin

Fungi involved in respiratory diseases?

Aspergillus fumigatus (causes aspergillosis, ariborne conidia) and Rizopus and Mucor (mold spores, mucoromycosis)

What are predisposing factors to fungi involved in respiratpry diseases?

Immunocomprimised state, cancer, diabetes

What does tinea mean?

Dermatophyte infection