Mycology - Fungi Flashcards
- introduction - general characteristics - subcellar structures - disease - classification
1
Q
Branch of biology dealing with fungi
A
Mycology
2
Q
Organism
- without chlorophyll
- with nucleus
- producing spores
- reproduces sexually (perfect) or asexually (imperfect)
- somatic structures have cell walls containing cellulose, chitin or both
A
Fungus
3
Q
water molds
A
Oomycetes
4
Q
algae
A
heterokonts
5
Q
stramenopiles
A
heterokonts (algae)
oomycetes (water molds)
6
Q
fruit mold
A
Botrytis cinerea
- botrys (grape) + itis (disease)
7
Q
Huitlacoche
A
Corn smut (origin: Mexico) - caused by pathogenic fungus Ustilago maydis
8
Q
Chlorophyllum molybdites
A
common name:
- false parasol
- green-spored parasol
- ‘vomiter’
9
Q
Macrolepiota procera
A
common name:
- The Edible Parasol Mushroom
- Lepiota
10
Q
Fungi used as biocontrol agents against insect pests
A
Entamopathogenic fungi
- White muscadine disease
11
Q
Unique caterpillar-fungus fusion
A
Yarsagumba/ Yarsha Gumba
- Ophiocordyceps sinensis
- world’s most expensive biological resource
- harvested btwn mid April-July
12
Q
Beneficial effects of fungi
A
- decomposition
- biosynthetic factories
- antibiotics
- model organisms for biochemical/genetic studies
- recombinant DNA technology
- edible
- nutritional supplements
- flavour
- important alkaloids
- malaria control
13
Q
harmful effects of fungi
A
- destruction of commercial goods
- animal/human diseases
- toxins
- plant diseases
- spoilage
- damage
14
Q
honey fungus of species Armillaria ostoyae
A
largest living fungus in the world
15
Q
general characteristics of fungi
A
- Eukaryotic
- non-photosynthetic
- heterotrophic
- general taxonomy is constantly in a state of flux
16
Q
Heterotroph
A
organism that must ingest or absorb organic carbon in order to be able to produce energy & synthesize compounds to maintain its existence
17
Q
eukaryotic organism
A
cells contain membrane bound cell organelles (nuclei, mitochondria, Golgi apparatus, ER, lysosomes, etc.)
18
Q
Rigid cell wall contains:
A
- Glucan
- Mannan
- Chitin (no peptidoglycan)
19
Q
Cell membrane contains:
A
- sterols (ergosterol)
- 80S ribosomes
20
Q
most common body structures:
A
- multicellular filaments (molds)
- single cells (yeasts)
21
Q
some species grow as either A or B or AB:
A
A: filaments
B: Yeasts
AB: both (dimorphic)
22
Q
Reproduction types:
A
- sexual (perfect)
- asexual (imperfect)
23
Q
fungi produce spores: T/F
A
True
24
Q
Fungal Organisms can grow in common media: T/F? If T, what temp? Name of media?
A
True; 20-25 C
- SabDex agar
25
Fungal Organisms can grow in blood agar: T/F? If T, what temp? What phase?
True; 37 C
| - In yeast phase
26
Fungal can form in 2 types of colonies: T/F? If T, what types of colonies?
1. Filamentous - mold
| 2. Yeast form - yeast
27
Mold: Macroscopic
- growth rate
- colony appearance
- pigment
- colony morphology
28
Mold: Microscopic
Vegetative mycelium
- develops inside substrate
| - provides support and absorbs nutrients
29
Reproductive mycelium
differentiation to support fruiting bodies, propagules
30
Mycelium
filamentous mass of hyphae
31
2 kinds of hyphae
1. septate hypha
| 2. coenocytic hypha
32
septa (crosswalls)
divide hyphae into compartments but not into individual cells
- in some groups, nuclei/cytoplasm can flow through hole or pore in center of septa
33
Filamentous structures - BODY
thallus and consists of hyphae
34
hyphae
long filaments of cells joined together
35
vegetative hyphae
obtain nutrients
36
aerial hyphae
bear reproductive structures
37
Yeast structure
- non filamentous, unicellular fungi
- spherical or oval
- reproduce by budding
- when buds fail to detach called: pseudohyphae
- e.g. Candida albicans
38
Candidiasis
- common normal flora of gut in animals
- usually commensal organism
- can become pathogenic during immunosuppression
39
Dimorphic fungi
- change from mycelial form (@room temp) to yeast (@37 C)
- regulated by:
- temp
- Co2 concentration
- pH
- levels of cysteine or other sulfahydryl- containing compounds
40
Fungal Repro: Sexual (Perfect)
- demonstrated in only few fungi
| - fusion of 2 haploid nuclei followed by MEIOTIC division of diploid nucleus
41
Fungal Repro: Asexual (imperfect)
- very effective
| - division of nuclei by MITOSIS and subsequent cell division by individual fungus
42
3 Mechanisms of Asexual Fungal Repro
1. Sporulation: followed by germination of spores
- e.g. Aspergillus and Penicillium
2. Fragmentation of hyphae
- e.g. Coccidioides immitis
3. Budding of yeast cells
- e.g. Candida and Cryptococcus
43
Except for dimorphic fungi and dermatophytes (pathogens), fungi rarely cause disease in healthy, immunocompetent animals. T/F?
True
44
Pathogenic fungi
- cause ringworm and more
- Common Mycoses
- Blastomycosis
- Histoplasmosis
45
Opportunistic fungi
seldom cause disease with exception of immunocompromised individuals
46
Factors which may predispose to fungal invasion of tissues
- immunosuppression
- prolonged antibiotic therapy
- immunological defects
- immaturity, aging, malnutrition
- exposure to heavy challenge of fungal spores
- traumatized tissue
- persistant moisture on skin surface
- neoplastic condition
47
Deep mycoses
Systemic mycoses
48
cutaneous mycoses
- superficial (on skin, hair, nails)
- keratinized outermost layers
- cutaneous (within skin, hair, nails)
- keratinized layers
- subcutaneous (beneath skin)
- dermis, SQ tissues, muscle, fascia, bone
49
fungal diseases classified according to 2 things:
1. mode of entry into the host
| 2. degree of tissue involvement
50
Cutaneous mycoses (dermatophytoses)
epidermal layers: evoke immune response caused by dermatophytes
- e.g. Trychophytum, Microsporum, Epidermophyton
51
Dermatomycoses
skin diseases due to other fungi like Candida
52
Superficial
outer skin layer: no immune response
| - caused mostly by yeast
53
Subcutaneous mycoses
chronic infection of subnormal tissues
54
Deep/Systemic Mycoses
mostly originating in lung by inhalation caused by virulent dimorphic fungi
- e.g. Coccidioidomycosis, histoplasmosis, blastomycosis
55
Superficial Infection
Tinea Versicolor
56
Immunity to Fungal infections
- cell-mediated
| - antibodies produced (with exception of superficial dermatophyte infections)
57
Granulomatous
lesions that resemble mycobacteriosis and other diseases caused by facultative intracellular bacteria
58
Disease: Ringworm
- aka dermatophyte infections/dermatophytoses
- causative fungus: microsporum spp, trichophyton spp.
- affects: all domestic animals & man
59
Disease: Aspergillosis
- causative fungus: Aspergilluss spp.
| - affects: cattle, horse, poultry
60
Disease: Candidiasis
- causative fungus: Candida albicans
| - affects: avian spp, dogs, cats, man, pigs
61
Disease: Blastomycosis
- causative fungus: Bastomyces dermatidis
| - affects: dogs, humans, cats, horses, and occasionally other animals
62
Dermatophytes (cutaneous mycoses)
- molds capable of parasitizing only keratinized epidermal structures
- aka dermatophytosis or ringworm
- zoonotic
- causative agents: microsporum
trichophyton
epidermophyton
63
Anthropophilic dermatophytes
human reservoir
64
Zoophilic dermatophytes
animal reservoir
65
Geophilic dermatophytes
soil reservoir
66
Ringworm
- superficial dermatophyte infection
| - caused by fungus: Trichophyton rubrum in humans
67
Pathology: Initial phase
subclinical or mild host response
68
Pathology: Later phase
more pronounced inflammatory response
69
Dermatophytosis in Cattle
T. verrucosum
70
Dermatophytosis in Horses
T. equinum
71
Dermatophytosis in Pigs
M. nanum
72
Dermatophytosis in Poultry
M. gallinae
| - Avian ringworm or favus
73
Opportunistic mycosis
- Candida albicans: Candidiasis
- Cryptococcus neoformans: Cryptococcosis
- Aspergillus sp.: Aspergillosis
74
Candidiasis
- caused by C. albicans and other Candida spp.
- most common opportunistic fungal infection
- superficial or deep
75
Superficial candidiasis
- may involve epidermal and mucosal surfaces
76
Deep (visceral) candidiasis major portals of entry
alimentary tract and intravascular catheters
77
Deep (visceral) candidiasis major organ sites involved
kidneys, liver, spleen, brain, eyes, heart and other tissues
78
Deep (visceral) candidiasis risk factors and predispositions
- long term courses of broad spectrum antibiotics
- cytotoxic chemotherapy
- cortiosteroids
- vascular catheters
79
Tx Antifungal agent
drug that selectively eliminates fungal pathogens from a host with minimal toxicity to the host
- inhibit DNA/RNA synthesis
- inhibit synthesis of glucans in cell wall
80
Amphotericin B
binds with ergosterol: a component of fungal cell membranes -> forms pores that cause cell leakage and cell death
81
Polyene Antifungal Drugs
Amphotericin, nystatin and pimaricin interact with sterols (ergosterol) in cell membrane
82
Azole Antifungal Drugs
Fluconazole, itraconazole, and ketoconazole inhibit cytochrome P450 dependent enzymes involved in biosynthesis of ergosterol
83
Allylamine and Morpholine Antifungal Drugs
Allylamines (naftifine, terbinafine) inhibit ergosterol biosynthesis
84
Antimetabolite Antifungal Drugs
5-fluorocytosine acts as an inhibitor of both DNA/RNA synthesis
85
Mycotoxins
- toxic secondary metabolites produced by fungi
- structurally diverse
- not essential to fungal growth
- produced periodically under fungal stress
86
one fungi/mold species may produce many different mycotoxins. T/F?
True
87
Several species may produce the same mycotoxin. T/F?
True
88
Type of mycotoxin produced by Aspergillus spp.
Aflatoxins
89
Claviceps purpurea
| mycotoxicosis?
- Yes
- rye mold
- produces ergot (alkaloid) -> ergotism (convulsive, gangrenous)
90
Aspergillus
| mycotoxicosis?
- Yes
- produces aflatoxin
- grows in many plant materials
- low levels of toxin -- carcinogenic (leads to aflatoxicosis)
91
Amanita phalloides
| mycotoxicosis?
- Yes
| - poisonous mushroom/toadstools
92
Equine Leukoencephalomalacia (ELAM)
- moldy corn toxicosis/poisoning
- mycotoxin disease of CNS
- most common mycotoxin-related syndrome in horses
- toxin produced by fungus Fusarium moniliforme
93
Porcine Pulmonary Edema Syndrome
Fumonisin toxicity
