Lecture 2: Fungal Structure and Morphology (9/4/24)

Differentiate Molds and Yeasts

• Molds: Grows in multicellular filaments, thread-like tubular structures (hyphae)

• Yeast: Grows/reproduces as a single cell through BUDDING

Describe hyphae

Multicellular filaments, thread-like structures

Describe budding of a yeast

• In a parent yeast cell, the nucleus will copy/divide

• Bud forms (bud receives a copy)

• Cytoplasm divides

• Chain of yeast forms (connected to parent yeast)

Both molds and yeasts are considered “__”

Fungi

What is mycelium?

Matlike network of hyphae

What is the area above the surface of substrate called? What about below?

• Aerial hyphae

• Vegetative hyphae

What is conidia?

Asexual reproductive elements

What grows on the aerial hyphae?

Reproductive hyphae and conidia (“fluffy stuff”)

What is septate hyphae? Draw if possible.

One hyphae separated by septum

What is coenocytic hyphae? Draw if possible.

Multiple hyphae in one area (separations are spread out)

What is septate hyphae w/ clamp connections? Draw if possible.

One hyphae separated by septum w/ a small bump

What is hyphae w/ arthroconidia and disjunctor cells? Draw if possible.

Hyphae surrounded by arthroconidium (may break apart and infect) and separated by disjunctor cells (space between the hyphae)

Name this hyphae

Antler hyphae

Name this hyphae

Modular hyphae (swelling)

Name this hyphae

Pectinate body

Name this hyphae

Spiral (coiled) hyphae

Name this hyphae

Racquet hyphae

Name this hyphae

Septate hyphae

Name this hyphae

Coenocytic (nonseptate) hyphae

Name this hyphae and its structures

• Pseudohyphae

• Yeast cells

What are these?

1: Yeast

2: Pseudohyphae

3: Hyphae

Asexual vs Sexual Reproduction in Fungi (Starting from spores)

• Asexual: Spores → Germination → Mycelium → Mitosis → Start again at spores

• Sexual: Spores → Germination → Mycelium → Plasmogamy → Heterokaryocytic stage → Karyogamy → Zygote → Meiosis → Start again at spores

Fungal Spore Characteristics

• Means of fungal reproduction

• Microscopic

• Sexual or Asexual

• Major source of fungal infection: Inhalation of spores or skin contact w/ spores

Types of Sexual Spores

• Basidiospore

• Ascospore

• Zygospore

Characteristics of Basidiospore

• Produced by basidiomycetes

• Born in a club-shaped structure called basidium

Characteristics of Ascospore

• Produced ascomycetes

• Produced in a sac called an ascus

• Usually 4-8 ascospores in ascus (varies by species)

Characteristics of Zygospore

• Thick walled spores formed when two sexually compatible hyphae of certain fungi fuse together

Asexual spores are also known as:

Conidia

Types of Asexual Spores

• Sporangiospore

• Conidiospore

• Arthrospore

• Chlamydospore

• Blastospore

Name the spore and its structures:

• Sporangiospore

• Sporangium: Sac where asexual spores are produced

• Columnella

• Sporangiophore

• Pausi-septate hyphae

• Septum (rare)

• Rhizonds (roots)

Where are the asexual spores of the sporangiospore produced?

In a sac called sporangium

Where is the sac (sporagium) located and what is it called?

At the end of the aerial hyphae and is called sporangiophore

Examples of Sporangiospore

• Rhizopus

• Mucor

• Absidia

Name the spore and its structures:

• Conidiospore (“Conidia”)

• Phialides

• Vesicle

• Conidiophore

• Foot cell (vegetative)

• Septate hyphae

Characteristics of Conidiospore

• Single celled/multi-celled spores born on tip or side of aerial hyphae (conidiophore)

• Can be found singly or in chains

Difference between Sporangiospore and Conidiospore:

Conidias are not produced inside any sac-like structure, unlike sporangiospores

Difference between a uniserate and biserate conidiospore:

Uniserate: 1 layer

Biserate: 2 layers (metulae = 1st layer)

Name the spore and its structures:

• Athroconidia

• Arthrospores

Characteristics of Arthroconidia

• Primitive spore

• Made by breaking up the fungal mycelium → hyphae separate, then fragment into arthrospores

Examples of Arthroconidia

• Trichosporon

• Geotrichum

• Coccidioides immitis **

Name the spore and its structures:

• Terminal (end)

• Intercalary (middle)

• Sessile (outside)

Characteristics of Chlamydospore

• Often formed during unfavorable conditions (too dry/hot)

• Purpose: Perennation (survival), not dissemination

• Thick-walled, single cell

  • Hyphae contacts → Loses water → Condenses cytoplasm → Thick-walled chlamydospore

• Will eventually germinate into new fungi when environmental conditions improve

Examples of Chlamydospore

Candida albicans

Name the spore and its structures:

• Blastospore

• Clusters of chlamydospores, psuedohyphae, blastoconidia

Name these asexual spores

• Arthrospores

• Chlamydospores

• Sporangiospores

• Conidiospores

• Blastospores

Characteristics of Blastoconidia

Results from the budding of a yeast:

• Asexual reproduction

• Results in bud from a parent cell

Asexual Spores of Ascomycetes: Macroconidia vs. Microconidia

Macroconidia

• Large asexual structures

• Thick/thin/smooth/rough walled

• Divided into cells w/ transverse septa

• Different shapes in ID: spindle, boat, pencil, cigar

Microconidia

• Small asexual structures

• Amount and arrangement aids in ID: May appear singly or in clusters

• More often the infectious form, not always