quiz 8 Flashcards
taxonomy
- hierarchical categorization of organisms
- originally organized by sexual morphology
nomenclature
- not the categorization of organization, just the non-scientific set of rules used to decide names of organisms (does not govern taxonomy)
describe the two-name system in fungi, and why it is now obsolete.
- “deuteromycota”- used to be their own phylum- fungi lacking known sexual stages
- catch-all morphological group
- if a species already named within this group was later discovered to have a sexual stage, it would be allowed to have two names
- two names were referred to as the teleomorph and the anamorph (together they make up the holomorph which is the whole fungus)
- only apply the anamorph name when it doesn’t have a teleomorph name
- now since we have dna analysis, we don’t need to use both names anymore- both sexual and asexual parts of the same individual will share the same DNA
- in 2011, dual nomenclature was banned
- some anamorph names are being protected rather than teleomorph just bc of context of which stage is more “important”- eg: asexual stages in human pathogens
Illustrate and describe the Pezizomycotan life cycle using proper mycological terminology.
- similar to ascomycotan life cycle
- ascospores of two different mating types, may grow into monokaryotic/haploid hyphae
- asexual stage- this haploid hyphae produces conidia
- two mating types meet and undergo plasmogamy–> form a primordium
- within the PRIMORDIUM, an ascogonium and antheridium (two different types of hyphae based on mating type) are joined together by a trichogyne bridge
- like in ascomycota, diploid ascogenous (from the ascogonium) hyphae develop
- hyphae grow and form a crozier’s hook that bends and forms a septa isolating two haploid nuclei (penultimate cell that is the mother cell for the ascus)
- karyogamy, then meiosis- another ascus begins to form (inside of a disc-like APOTHECIUM)
Describe the general characteristics of the Class Eurotiomycetes.
- variable ascomata and forms of conidiogenesis, but majority of groups produce cleitotheccia
- mostly saphrophytic
- animal pathogens, toxin producers, some plant pathogens
List the three major orders within Eurotiomycetes.
Eurotiales
Onygenales
Chaetothyriales
Eurotiales
- mostly saprophytic, often human pathogens, often xerophilic/tolerant and/or osmophilic/tolerant
- sexual: asci round, contain 8 ascospores, cleistothecial, prototunicate and often from stroma spores often have equatorial rings
- asexual: aspergillosis and penecillium
Onygenales
- sexual stages similar to those in Eurotiales
- asexual stages: often thallic anamorphs
- saphrophytic, many keratinophilic
Chaetothyriales
- black yeast-like organisms
- common anamorphs
- animal pathogens, mildews
- halophilic (salt)
- rock fungi
Describe mycotoxins and their biological purpose.
- secondary metabolism- not produced to survive
- establishing niche, ward off competitiors/predators/ help the host
Provide an example of a “friendly chemical” produced by eurotialian fungi. Who (species) produces it, and how does it work?
Penicillin
- kills staph
- P. notatum
- penicillin like many other fungi produces anti fungal substances to ward of bacterial competitors
- penicillin produces Beta-lactam derived from amino acids- disrupts peptidoglycan in G+ bacteria
- gram+ have a thick wall layer of peptidoglycan
- war in Europe- many people killed/ disfigured from infection
The three major human pathogens within the Onygenales
- Dermatophytes (“tinea infections”)
- Histoplasma capsulatum (and Blastomycosis)
- Coccidioidomycosis
Name the fungi responsible for Chalkbrood of bees and list the order and class they are found in. Describe the diseases and the fungal morphologies associated with them
- Ascoscosphaera apis
- class Eurotiomycetes
- order Onygenales
- Infect larvae and leave them looking white, mummified
- association with pollen and feces, easy for bees to become infected
- asci within a cleistothecium are released, which is how the fungus spreads sexually
Provide an example of a eurotialian mycotoxin.
Aflatoxin- A. flavus/parasiticus on oil rich plants
- corn, peanut, cotton, tree nuts
-infect plant in the field, grow and produce toxins in storage
Histoplasmosis (and Blastomycosis)- Describe them, be able to list the fungus responsible, and describe how these fungi infect humans.
- Lung infections
- Histoplasma capsulatum
- bat guano, bird droppings
- common in HIV/AIDS patients
- Dimorphic yeast at 37deg C
- environmental form that produces micro and macro-conidia- inhaled by humans, develops into a yeast stage within human lungs where it can infect and parasitize human lungs
Blastomycosis
- common in tropical areas
- infects similarly to Histoplasma capsulatum
Dermatophytes- Describe them, be able to list the fungus responsible, and describe how these fungi infect humans.
- ringworm, athletes foot
- tinea capitis, tinea pedis,
- fungi mostly with microsporum, epidermophyton asexual stages
Coccidioides- Describe them, be able to list the fungus responsible, and describe how these fungi infect humans.
- aka valley fever
- cause coccidiomycosis
- caused by C. immitis or C. posadasii
- endemic to dry valleys of western countries
- persistent and possibly life threatening bronchitis in even healthy people
- soil-borne- have septate hyphae that produce arthrospores
- arthrospores undergo thallic conidiogenesis- (hyphae become fragmented)- to become arthroconidia
- arthroconidia inhaled, become spherules that mature and divide to release endospores which spread throughout the body
Name the fungi responsible for Snake Fungal Disease and list the order and class they are found in. Describe and explain the fungal morphologies associated with them.
- Ophidiomyces ophidiiocola
- class Eurotiomycetes
- order Onygenales
- consumes keratin in snakes
- mortality seems to be 100%, happening across species
- scabs, nodules, ulcers, irregular molting, etc
- ## thallic conidiogenesis
