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Infection and Immunology > Fungal kingdom and disease > Flashcards

Fungal kingdom and disease Flashcards

Lecture 1

1
Q

Nutrition

A

Heterotrophs

- specifically osmotrophs

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2
Q

Osmotrophs

A
  1. Digest food outside body
  2. Secrete hydrolytic enzymes
  3. Absorb organic nutrients
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3
Q

Fungal lifestyles

A

Saprophytes
= live off dead matter
Pathogens
Mutualists

Can be more than one, depending on environment

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4
Q

Cell wall

A

Chitin-based polysaccharide cell wall

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5
Q

Aerobic or anaerobic?

A

Usually aerobic

Some yeasts are facultative or obligate anaerobes

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6
Q

6 fungal kingdoms

A 
Basidiomycota 
Ascomycota
Glomeromycota
Zygomycota
Chytridmycota
Cryptomycota
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7
Q

Basidiomycota

A

Basidia

= structure that releases spores

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8
Q

Ascomycota

A

Produce an ascus
= sac of 8 ascospores

Ascus develops on ascocarp

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9
Q

Glomeromycota

A

Arbsucules

V large spores

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10
Q

Zygomycota

A

Zygospores
- V resistant spores
Phototropism

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11
Q

Chytridmycota

A

Motile flagellated asexual zoospores

Only motile fungi

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12
Q

Cryptomycota

A

Highly reduced
No chitin in cell wall
Endoparasitic

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13
Q

Fungi 1st to colonise land

A

> Generate soil
Nutrient transport
Nitrogen cycle

Consumed early bacteria + algae

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14
Q

Lichen

A

Oldest example of a symbiosis

  • Fungus provides structure/home
  • Alga provides energy/sugar via photosynthesis

Colonisers of a new land

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15
Q

Mycorrhizal fungi

A

(Glomeromycota)

Obligate symbionts
Associate w/ 80% of plants
Form highly branched ‘arbuscules’ within plant cells

Provides greater access to nutrients
Improved disease, pest + stress tolerance

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16
Q

Ascocarp fruiting body variations

A

Apothecium
Perithecium
Cleistothecium

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17
Q

Ascomycete life cycle

A
  1. Ascogonia + antheridia fuse
  2. Ascocarp with dikaryotic hyphae forms
  3. Dikaryotic ascus -> into diploid ascus
  4. Meiosis
    = 4 ascospores
  5. Mitosis
    = 8 genetically distinct ascospores
18
Q

Basidiomycete morphology

A

Club fungi

Gills covered in basidia
which produce spores

19
Q

Basidiomycete life cycle

A
    • and - hyphae fuse
      = eukaryotic mycelium
  2. basidiocarp (fruiting body) forms
  3. gills lined with basidia produce genetically distinct basidiospores
  4. spores develop into + and - haploid mycelia
20
Q

Which factors contributed to the rise of mammals?

A

Fungal bloom at end of Cretaceous

Large reptiles susceptible to ecosystem disruption

Small mammals resistant to fungal disease

21
Q

Types of fungal pathogens

A

Opportunistic pathogens
= cause disease in immunocompromised individuals

Primary pathogens
= causes damage/ disease in healthy individuals

22
Q

When an opportunist becomes a pathogen

A

Fungi persist in symbiosis with host + bacteria

Disrupting the balance (via mucosal damage, antibiotics + immune defects) promotes fungal outgrowth + disease

23
Q

Candida albicans

= dimorphic

A

= unicellular yeast that replicates by budding but can switch to hyphal growth

24
Q

Candida albicans

= commensal org

A

= derives food from another org without harming it

e.g. member of the human microbiome

25
Q

Candida albicans

= obligate diploid

A

Generates genetic diversity in parasexual cycle

Parasex = recombination of genetic material w/out meiosis or zygote formation via fertilisation

26
Q

Candidiasis

= thrush

A

Normally candida reside on mucous membranes w/out causing infection

Switch to hyphal growth promotes disease

27
Q

Invasive candidiasis

= Candidemia

A

Systemic infection
(=affects whole body)

Penetrates layers of tissue

  • > enters bloodstream
  • > enters organs e.g. lungs
28
Q

Invasive candidiasis

- risk factors

A 
Chemo
Surgery 
Low-birthweight
Catheters 
Neutropenia 
(=low level of neutrophils = type of WBC)
29
Q

Candida glabrata

A 
V different to C.albicans:
> haploid 
> asexual 
> doesn't form hyphae
> don't know who it causes disease

Urinary tract + bloodstream infections

30
Q

Candida parapsilosis

A 
>Diploid
>Commensal on skin
>Cannot form hyphae - exists in yeast/pseudohyphae form
>Not obligate human pathogen 
>Associated w/ biofilm on implants
31
Q

Aspergillus fumigatus

= filamentous ascomycete

A

Food spoilage mould + mycotoxin producer

Not a commensal org

Optimum growth at 25-40*C
- evolved to grow in compost heaps = similar temp to human bodies

32
Q

Aspergillosis

A

= balls of fungal fibres, blood clots + WBCs in lungs + sinuses
caused by Aspergillus

Source: abundance of airborne spores from
compost heaps + dirty air con

33
Q

Cryptococcus neoformans

= basidiomycete yeast

A

Unicellular, haploid yeast - replicates by budding

Forms polysaccharide capsule

Sex + monokaryotic fruiting

34
Q

Cryptococcal meningitis

A

C. neoformans infection of the brain

AIDS-defining illness

Cause:
airborne basidiospores + dried yeasts

35
Q

Cryptococcus gattii

A

Lives on trees

Infects lungs by inhaling airborne, dried yeast cells or spores

Travels via bloodstream

36
Q

Coccidiodes immitis

= primary pathogen

A

Desert soil dwelling

Grows as hyphae

  • > fragments at ends
  • > into arthroconidia

Dimorphic structures fill with endospores
-> when mature, rupture + spread spores

37
Q

Coccidiomycosis

= Valley fever

A

Caused by Coccidiodes immitis

Risk factors: activities associated with dust + airborne dirt

Pulmonary + cutaneous

38
Q

Histoplasma capsulatum

= primary pathogen

A

Dimorphic fungus

  • in soil, low temp = grows as hyphae
  • in lungs, high temp = grows as yeast -> budding growth

Found in bird + bat faeces

39
Q

Primary vs opportunistic pathogen

A

Primary = infecting healthy hosts

Opportunistic = infecting immunocompromised hosts

40
Q

Life-threatening fungal infections

A

> 2mil each year

V high mortality rate

41
Q

Fungal infections commence from…

A

> Disruption of commensal association

> Acquired by breathing in fungal spores

Infection and Immunology (13 decks)

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