Ch. 12- Fungi

reproductive strategy of Zygomycota ex) * Rhizopus (bread mold)

***Conjugation fungi*** -Have ==> CoenoCytic hyphae -Produce ==> Zygospores (sexual) ==> Sporandispores (asexual)

reproductive strategy of Basidiomycota ex) * Amanita muscaria (mushroom red cap with neurotoxins) * amanita phalloides (death cap mushroom)

***club fungi*** -Have ==> septate hyphae - Produce ==> Basidiospores (sexual) ==> conidiospores (asexual)

Types of Asexual Fungal Spores

1) Sporangiospores 2) conidiospores/conidia

what is Basidiospores

Basidiospores are formed externally on a base pedestal called a basidium (Figure 12.10). (The common name of the fungus is derived from the club shape of the basidium.) There are usu- ally four basidiospores per basidium. Some of the basidiomycota produce asexual conidiospores

SUBCUTANEOUS fungal dzs/infxns

EXAMPLES= - sporotrichosis (caused by microbe: Sporothrix)

SEXUAL reproduction RECAP

Sexual Spores A fungal sexual spore results from sexual repro- duction, which consists of three phases: 1. Plasmogamy. A haploid nucleus of a donor cell (1) penetrates the cytoplasm of a recipient cell (2). 2. Karyogamy. The (1) and (2) nuclei fuse to form a diploid zygote nucleus. 3. Meiosis. The diploid nucleus gives rise to haploid nuclei (sexual spores), some of which may be genetic recombinants. The sexual spores produced by fungi characterize the phyla. Clinical identification is based on microscopic examination of asexual spores, because most fungi exhibit only asexual spores in laboratory settings.

what are SUBCUTANEOUS fungal dzs/infxns

Subcutaneous mycoses are fungal infections beneath the skin caused by saprophytic fungi that live in soil and on vegetation. Sporotrichosis is a subcutaneous infection acquired by garden- ers and farmers (Chapter 21, page 596). Infection occurs by direct implantation of spores or mycelial fragments into a puncture wound in the skin.

reproductive strategy of Ascomycota ex) * Aspergillus (lung infxn) * truffles

***Sac fungi*** -Have ==> septate hyphae ==> yeasts -Produce ==> Ascospores (sexual) ==> conidiospores (asexual)

COccidiodoMycosis

*S/SX* -fever -chest pain -flu like sx's -rash/joint pain -persistent FATIGUE -SERIOUS complication ==> Fungal Meningitis *Causative agent* - coccidioides immitis *type of microbe* - AscoMycota Phylum *transmission* - inhalation of wind & dust *Body part affected* - Most infections are not apparent, and almost all patients recover in a few weeks, even without treatment. The symp- toms of coccidioidomycosis include chest pain and perhaps fever, coughing, and weight loss. In less than 1% of cases, a progressive disease resembling tuberculosis disseminates throughout the body. A substantial proportion of adults who are long-time residents of areas where the disease is endemic have evidence of prior infection with C. immitis by the skin test. *Diagnosis* -Diagnosis is most reliably made by identifying the spherules in tissue or fluids. The organism can be cultured from fluids or lesions, but laboratory workers must use great care because of the possibility of infectious aerosols. Several serological tests and DNA probes are available for identifying isolates. A tuberculin-like skin test is used in screening. ==> detect antibodies in blood (ELISA) ===> CXRAY ===> Biopsy, culture, microscope *Treatment* - YES= recovery in 6 mo. but may not be cured entirely *Geographical* - dry alkaline soil - Southwest US (Ca, Az, Texas, N. Mexico) *life cycle* arthroconidia ---> spherule @ lungs ---> endospores within Spherule ---> disseminate *risk factors when you have valley fever* 1) corticosteroids= this is used with people who want to reduce inflammation seen in AS & RA (when reducing inflammation, you've deceased immune response, this makes Valley Fever patients vulnerable) 2) Diabetes = b/c a chronic dz also makes you immunocompromised 3) 2rd trimester= wokmens immunity drops in order to host parasite (baby, lulz) 4) HIV/AIDS...autoimmune..

Histoplasmosis = histoplasma capsulatum

*S/Sx* -fever -chest pain -joint pain -fatigue -may cause meningitis *Causative agent* - histoplasma capsulatum *type of microbe* -AscoMycot PHYLUM *transmission* - microconidia spores are inhaled *Body part affected* -mucus -lungs -lymph notes -blood *Diagnosis* - Blood or Urine for Serological tests of antibodies via ELISA - biopsy *treatment* - amphotericin B - itraconazole *Geographical* - midwest US - mississippi + ohio rivers -especially in bird + bat droppings. *life cycle* mold ---> yeast @ humans ---> phagocytosed by macrophages ---> spread to Lymph Nodes ---> then bl0o0o0odddd EEEEEKKK!

Where are conidiospores/ conidia formed

- conidiophore *conida= dust like

Where are Sporangiospores formed

- sporangium

what is an Ascospore

-An ascospore forms when the nuclei of two cells that can be either morphologically similar or dissimilar fuse. These spores are produced in a saclike structure called an ascus (Figure 12.9, lower right). The members of this phylum are called sac fungi because of the ascus.

what is Ascomycota

-Ascomycota The Ascomycota, or sac fungi, include molds with septate hyphae and some yeasts. Their asexual spores are usually conidia produced in long chains from the conidiophore. The term conidia means dust, and these spores freely detach from the chain at the slightest disturbance and float in the air like dust.

how to differentiate Histoplasmosis from 1) TB 2) PNA 3) FLU

1) IGRA to rule out tb 2) Abx Tx to rule out PNA 3) wait 1-2 wks to rule out influenza

2 examples of systemic mycoses (systemic fungal infections)

1) Valley fever = coccidioides immitis 2) Histoplasmosis = histoplasma capsulatum

ASEXULA reproduction RECAP (pg. 323-324)

Asexual Spores Asexual spores are produced by an individ- ual fungus through mitosis and subsequent cell division; there is no fusion of the nuclei of cells. Two types of asexual spores are produced by fungi. One type is a conidiospore, or conid- ium (plural: conidia), a unicellular or multicellular spore that is not enclosed in a sac (Figure 12.6a). Conidia are produced in a chain at the end of a conidiophore. Such spores are produced by Penicillium and Aspergillus (a-sper-JIL-lus). Conidia formed by the fragmentation of a septate hypha into single, slightly thick- ened cells are called arthroconidia (Figure 12.6b). One species that produces such spores is Coccidioides immitis (KOK-si-dē- oi-dēz IM-mi-tis) (see Figure 24.17, page 699). Another type of conidium, blastoconidia, are formed from the buds of its parent cell (Figure 12.6c). Such spores are found in some yeasts, such as Candida albicans and Cryptococcus. A chlamydoconidium is a thick-walled spore formed by rounding and enlargement within a hyphal segment (Figure 12.6d). A fungus that produces chla- mydoconidia is the yeast Candida albicans. The other type of asexual spore is a sporangiospore, formed within a sporangium, or sac, at the end of an aerial hypha called a sporangiophore. The sporangium can contain hundreds of sporangiospores (Figure 12.6e). Such spores are produced by Rhizopus.

List 3 major groups of medically important fungi, grouped by reproductive Strategy

Domain= Eukaryote Kingdom= Fungi PHYLUMS= 1) Zygomycota 2) Ascomycota 3) Basidiomycota

CUTANEOUS fungal dzs/infxns

EXAMPLES= - athletes foot - ringworm - jock itch

what are CUTANEOUS fungal dzs/infxns

Fungi that infect only the epidermis, hair, and nails are called dermatophytes, and their infections are called dermatomycoses or cutaneous mycoses (see Figure 21.16, page 596). Dermatophytes secrete keratinase, an enzyme that degrades keratin, a protein found in hair, skin, and nails. Infection is transmitted from human to human or from animal to human by direct contact or by contact with infected hairs and epidermal cells (as from barber shop clippers or shower room floors).

fungi reproductive strategies

I. Asexually * Filamentous fungi can reproduce asexually by fragmentation of their hyphae * formation of spores * after a mold forms a spore, the spore detaches from the parent and germinates into a new mold * When these spores germinate, they become organisms that are genetically identical to the parent

what is Basidiomycota

The Basidiomycota, or club fungi, also possess septate hyphae. This phylum includes fungi that produce mushrooms.