FILAMENTOUS
ASCOMYCETES I
IB 371 - General Mycology
Lecture 21
Thursday, November 6, 2003
FILAMENTOUS ASCOMYCETES

Mycelium septate

Septa with single pore or many small
pores

Woronin bodies present at pores

Nuclei haploid, except during meiosis

Antheridia & ascogonia may or may
not be formed prior to meiosis

Ascogenous hyphae formed
SEPTAL PORE
Woronin Bodies
NUCLEUS PASSING
THROUGH PORE
GENERAL LIFE CYCLE
MEIOSIS &
ASCOSPOROGENESIS
In-class activity

How is a crozier like a clamp connection?
ASCOGONIA
TEM of crosier by Charles Mims
Crosiers &
Developing
Asci
TEM of developing ascus by Charles Mims
TEM of ascospores developing within an ascus by Charles Mims
TEM of maturing ascospores within an ascus by Charles Mims
TYPES OF ASC0MATA
Cleistothecium - round & completely
closed
 Apothecium - open & saucer shaped
 Perithecium - flask shaped with an
opening at the top
 Pseudothecium - may look like a
perithecium but it is stromatic & is
formed prior to the ascogenous hyphae

TYPES OF ASCI
Prototunicate - one functional wall that
deliquesces early
 Unitunicate - one functional wall that
remains as one wall when ascospores
are discharged
 Bitunicate (fissitunicate) - two
functional walls that separate when
ascospores are discharged

Hamathecium
None
 Paraphyses
 Apical paraphyses
 Pseudoparaphyses
 Catenophyses

ONYGENALES

Sexual apparatus - antheridium
surrounded by a coiled ascogonium

Homothallic or heterothallic

Asci unitunicate, globose to subglobose

Ascus wall breaks down to release
ascospores (deliquescent)

Ascospores usually non-septate
(amerospores)
ONYGENALES

Ascoma is a cleistothecium of thin
cottony hyphae or very thin layer of
pseudoparenchyma tissue

Peridial hyphae (peridium = wall of
cleistothecium) similar to vegetative
hyphae, colored and/or rough walled
ONYGENALES

Anamorphs are solitary holoblastic
(determinate) or arthric (thallospores)

Taxonomic characters - peridial wall
ornamentation, ascospore characters

Ecology - keratinophilic, cellulolytic saprophytes and parasites of animals

Habitat - soil, plant debris, faecal pellets of
carnivores, birds’ nests and droppings, hoofs
and horns
PATHOGENS OF HUMANS

ringworm (tinea), athletes foot, jock itch

Trichophyton (A)/ Arthroderma (T)

Microsporum (A)/ Nannizzia (T)

Geophilic - soil inhabiting species that are only
occasionally pathogenic to humans

Zoophilic - live on animals but occasionally
infect humans

anthropophilic - species that live only on
humans
DERMATOPHYTES

Keratinophylic - live on hair, nails, dead skin
cells (protein keratin)

Symptoms caused by enzymes that irritate
epidermal cells

Treatment may be systemic (griseofulvum) or
topical (azole antifungals, ciclopirox, others)
NORTH AMERICAN
BLASTOMYCOSIS
Blastomyces dermatitidis (A) /
Ajellomyces dermatitidis (T)
 Thought to occur in soil in midwest,
US-Canadian border from the Great
Lakes to the east coast.
 Infection through inhalation of conidia
into the lungs

NORTH AMERICAN
BLASTOMYCOSIS
fever, chills, cough, chest pain,
pneumonia (sometimes fatal), skin
lesions
 fungus is dimorphic - filamentous in
nature, yeast-like in body (or above
30C)
 Itraconazole daily for six months or if
life threatening, amphotericin B

dimorphic - yeast stage
HISTOPLASMOSIS




Histoplasma capsulatum (A) / Emmonsiella
(Ajellomyces) capsulatum
Grows as hyphae in soil enriched with bird
droppings
Ohio and Mississippi river valleys, Great
Lakes to east coast, Florida, Texas
Infection by breathing in conidia
HISTOPLASMOSIS

most people remain asymptomatic

fever, chills, headache, chest pain, malaise,
nodules in the lung

chronic pulmonary histoplasmosis mimics TB
(diagnosis is very important)

acute disease requires treatment with
amphotericin B, followed by itraconazole

immunocompromised patients require lifelong
treatment if infected
Conidium of H. capsulatum
Yeast stage of H. capsulatum
VALLEY FEVER

aka desert rheumatism, California disease occurs in desert SW, Mexico, SA

Coccidioides immitis (only imperfect state
known, connected to Onygenales by 18S rDNA sequences)

Inhalation of conidia (arthrospores),
symptoms somewhat similar to
histoplasmosis

Most people recover but sometimes the
disease is fatal
EUROTIALES
Asci free on mycelium or in ascomata
 Ascomal wall thin, mesh-like or solid
layer
 Sexual fusion usually by a trichogyne
and undifferentiated hypha
 Asci spherical to ovoid, evanescent

EUROTIALES

Ascospores 1-celled, oblate,
spherical, globose

Ascospores smooth or with
reticulations, spines or thickened rings

Conidial states phialidic, conidia
seceding schizolytically, in dry chains
EUROTIALES

Ubiquitous in distribution

Found commonly in soils and on
plant litter

Associated with cellulosic, starchy
or oily substrates
EUROTIALES

Decomposers

Agents of biodeterioration

Human pathogens (aspergillosis,
penicilliosis)

Aflatoxin & ochratoxin production
EUROTIALES

Important in cheese industry

Production of industrially important
acids (citric, gallic, fumaric, oxalic,
gluconic), and enzymes (alphagalactosidase)

Production of antibiotics (penicillin,
cephalosporin, griseofulvum
PENICILLIUM
Teleomorph genera –
 Eupenicillum
 Talaromyces

Discovery of penicillin

Changed the world.

In 1928, Alexander Fleming found P. notatum
growing on a Petri dish (dish is still preserved).

In 1939, Howard Florey & Ernest Chain began
work on how to use and identify the antibiotic
produced by P. notatum.

In 1941, work began in Peoria, IL, to increase
production of the antibiotic. “Moldy Mary”
brought in a moldy melon colonized by the high
yielding species, P. chrysogenum.
Discovery of penicillin

In 1942, the first patient was treated
successfully in New Haven,
Connecticut (Anne Miller).

In 1945, Fleming, Florey & Chain
received the Nobel Prize for their
work.
PENICILLIUM
From Hanlin, 1998. Illustrated Genera of Ascomycetes Vol II
From Hanlin, 1998. Illustrated Genera of Ascomycetes Vol II
ASPERGILLUS
Teleomorph genera  Eurotium
 Neosartorya
 Emericella

Eurotium/Aspergillus
ASPERGILLUS
http://www.bsu.edu/classes/ruch/msa/geiser/1.jpg
Conidial state of Aspergillus (Picture from David Geiser)
Hülle cells (picture from David Geiser)
http://www.bsu.edu/classes/ruch/msa/mims/1-51.jpg
Young conidiophores of Aspergillus (SEM from Charles Mims)
Mature conidiophores of Aspergillus (SEM from Charles Mims)
SEM of conidiogenesis in Aspergillus (from Charles Mims)
SEM of conidiogenesis in Aspergillus (from Charles Mims)
EUROTIUM ASCI
ASCOSPORES OF EUROTIUM
From Hanlin, 1998. Illustrated Genera of Ascomycetes Vol II