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
