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50 Cards in this Set
- Front
- Back
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What is mycology? |
Study of great number of multicellular, unicellular or microscopic organisms, includes their genetic/biochemical properties, taxonomy and use/danger to humans -Fungi |
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What are the characteristics of fungi? |
NO chlorophyll nucleus spore producing sexual/asexual filamentous/branching structures Cell wall composition: cellulose, chitin or both Cell wall contains: chitin, glucan and mannan over 1 million different species (70,000 described) |
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What are the benefits from fungi? |
Decomposition antibiotics biosynthetic factories edible recombinant DNA technology nutritional supplements alkaloids for medical use |
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How are some fungi harmful? |
Destruction to food disease (animal, human, plants) toxins Spoilage allergies |
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How are statins good for our diets? |
Statins can control cholesterol |
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Can fungi be used as biocontrol agents against insects? |
Yes Entamopathogenic fungi |
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What are some poisonous mushrooms? |
Death cap Liberty cap (magic mushroom) Fly agaric (red and white mushrooms) |
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What are some general characteristics of mushrooms? |
Eukaryotic Non-photosynthetic Metabolism: Hetertrophic Cells contain: nucleus, mito, golgi, ER, lysosomes have RIGID cell wall (glucan, mannan, chitin) Non-motile Membrane contains: sterols & 80S ribosomes |
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What is the largest organism in the world? |
Mushroom (Honey fungus, 2,200 acres, 2,400 years old)
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What are Beta-glucans used for medically? |
a drug used for anti fungals -prevents osmotic lysis and protects against mechanical injury and entrance of harmful macromolecules |
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What are the most common body structures (colonies) for fungi? |
multicellular filaments (molds) single cells (yeasts) *Some grow as either or, some grow as both |
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What temp does most fungi grow at? |
20-25 degrees C *some grow in blood agar in yeast phase at 37 degrees C |
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What are the characteristics of macroscopic mold? |
Can have fast, moderate, or slow growth rates Colony appearance=textured and shiny Colony morphology=can be fuzzy or smooth |
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What are the characteristics of microscopic mold? |
Vegetative mycelium-develops inside the substrate, provides supports, absorbs nutrients Reproductive mycelium-differentiation to support the fruiting bodies, propagules |
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What are fungal filaments called and how can their structures differ? |
Hypha mass of hyphae makes up mycelium Aerial hypa=above (bulbs) Vegetative hypha=below (roots) |
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What are the two kinds of hyphae? |
Septate Hypha=septa (cross walls) divide the hyphae into compartments but not into cells Coenocytic Hypha=in some groups nuclei and/or cytoplasm can flow through a hole or pore in the center of these septa |
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Characteristics of filamentous fungi |
ex: mold, fleshy fungi body= thallus or hyphae Hyphae= long filaments of cells joined together vegetative hyphae: obtain nutrients areial hyphae: bear reproductive structures mycelium= filamentous mass of hyphae |
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Characteristics of yeast fungi |
Ex: candida albicans Non-filamentous unicellular fungi which are spherical or oval (bowling pin shaped) Reproduce by budding When buds fall off or detach, they are called pseudohyphae Colonies: mucoid or moist on plate |
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What are dimorphic fungi? |
Change from mycelial form (@ room temp) to yeast (@ 37 degrees C or in tissues of animals) -Dimorphism is regulated by factors like: temp CO2 conc. pH levels of cysteine or other sulfhydryl containing compounds |
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Explain how sexual reproduction works in fungi |
-only demonstrated in a few fungi -fusion of 2 haploid nuclei followed by meiotic division of the diploid nucleus -haploid +/- hyphae fusion=diploid gametangium -meiosis=haploid spores=haploid organism |
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Explain how asexual reproduction works in fungi |
-very effective -division of nuclei by mitosis and subsequent cell division by and individual fungus |
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What are the 3 mechanisms for asexual reproduction? |
Sporulation: followed by germination of spores (Aspergillus and penicillium) Fragmentation: of hyphae (Coccidia) Budding: of yeast cells (Candida and Crypto) |
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Why don't fungus dry out? |
Asexual reproduction produces spores (clones) that can be thick walled and resist water loss |
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Do fungi cause disease in healthy, immunocompetent animals? |
No, they rarely cause disease unless they accidently penetrate host barriers |
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Which fungi cause disease? |
Dimorphic fungi Dermatophytes Pathogenic fungi that cause ringworm and mycoses (blastomycoses, histoplasmosis) |
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What are some factors that can make a fungi pathogenic? |
-Proteolytic enzymes -Synergistic action with some bacteria -favorable environments (moisture/warmth) -hyphae grow centrifugally (topical ringworm lesion) -Can be transmitted through direct contact (some indirect by fomites) |
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What are the factors that may predispose to fungal invasion? |
-immunosuppression/immunological defects -prolonged antibiotic therapy -immaturity, age, malnutrition -traumatized tissue -Persistent moisture on skin surface -Exposure to heavy challenge of fungal spores |
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What are the routes of entry for fungi? |
-Nasal sinuses -lungs -blood vessels -esophagus -stomach -intestines -skin ***Fungal diseases are classified according to mode of entry into host |
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What organs do deep tissue/systemic mycoses affect? |
brain lungs heart spleen liver kidney |
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Classification of cutaneous mycoses |
Superficial (on skin/hair/nails-caused by yeast) Cutaneous (w/in skin/hair/nails-dermatophytoses) Subcutaneous (beneath skin-chronic infection) Deep tissue/systemic (mostly in lung by inhalation) |
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What fungus causes ringworm and which animals are affected? |
Microsporum, Trichophyton All domestic animals humans (zoonotic) |
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What fungus causes Blastomycosis and which animals are affected? |
Blastomyces dermatidis Dogs, humans, cats, horses, others (zoonotic) |
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What fungus causes Aspergillosis and which animals are affected? |
Aspergillus Cattle/horse/poultry |
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What fungi are opportunistic mycosis? |
Candida albicans Cryptococcus neoformans Aspergillus |
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What are some characteristics of Candidiasis? |
-MOST COMMON opportunistic fungal infection -Superficial or deep |
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What is antifungal treatment? |
An antifungal agent is a drug that selectively eliminates fungal pathogens from a host with minimal toxicity to the host. Ex: Amphotericin B binds with ergosterol forming pores that cause leakage of ions cause fungal cell death |
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What are the 4 antifungal drug mechanisms? |
Polyene: Amphotericin, nystatin, pimaricin (interact with sterols in membrane) Azole: Fluconazole, Itraconazole, Ketaconazole (inhibit biosyn. of ergosterol) Allylamine/Morpholine: Allylamines (inhibit ergosterol biosyn.) Antimetabolite: acts as an inhibitor of both DNA and RNA syn. |
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What are mycotoxins? |
structurally diverse fungal metabolites, not essential to fungal growth and produced under fungal stress can contaminate food leading to nutrient losses and produce adverse effects on animal and human health |
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What is mycotoxicosis? |
Groups of illnesses and disorders from mycotoxins Rye mold-leads to ergotism Aspergillus-produces aflatoxin, grows in plants materials Amanita phalloides-poisonous mushroom |
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What are Dermatophytes? |
-Cutaneous mycoses -Molds that can only infect keratinized epidermal structures (skin, hair, feathers, horns, hooves, claws, nails) -also called ringworm -zoonotic -Causative agents: Microsporum, Trichophyton, Epidermophyton |
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What is anthrophilic? Zoophilic? Geophilic? |
Human reservoir Animal reservoir Soil reservoir |
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What does the initial phase of pathology involve? |
subclinical or mild host response Accelerated keratinization and exfoliation Scruffy appearance and some hair loss (alopecia) |
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What does the later phase of pathology involve? |
More pronounced inflammatory response -Erythema to vesiculopustular reactions -rough circular pattern, inflamed margins (ringworm) **Ringworm usually regresses spontaneously within a few weeks/months |
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What are some lab diagnosis for ringworm? |
-animal appearance (lesion) -Woods lamp (filtered uv light-will fluoresce green due to a tryptophan metabolite) -skin scraping/hair examination -staining techniques (permanent ink, lactophenol, cotton blue, dimethylsulfoxide) -cultured at 25 degrees C for 3 weeks |
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What is the treatment and control of fungal-infected animals? |
-isolation -lime sulfur or miconazole shampoo -clip hair -Systemic therapies (itraconazole, fluconazole, griseofulvin, terbinafine) -discard contaminated bedding/grooming equipment -no effective vaccines |
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What do you need to be careful of when administering systemic therapies for fungal infections? |
Teratogenicity (abnormalities of physcial development especially in fetus) |
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How are other species affected by Dermatophytosis? |
Cattle-affects calves, have a vaccine in europe Horses-affects young, limited vaccines Pigs-no age predilection Poultry-Avian ringworm, affects comb and wattles, may invade feather follicles |
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What are the characteristics of the phylum Microsporidia? |
-obligate intracellular protozoan parasites -unique (classified in separate phylum) -Infect every major animal group (mostly arthropods and fish) -now known to be related to fungi (originally thought to be basal amitochondriate eukaryotes) -All are spore forming (spore size varies) -More than 1200 species, 143 genera |
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What is special about spores? |
they are resistant infectious stages capable of surviving external environmental conditions |
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What are the microsporidian life cycles? |
2 proliferative cycles: sporogeny or merogony (one or two hosts may be utilized) |
