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+ ‘Fungi Imperfecti’. Fig 31.4. Some fungi can’t be classified into a division because the sexual stage is never seen. They’re called ‘Imperfect Fungi’. http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html The organisms of the fungal lineage include

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+ ‘Fungi Imperfecti’

Fig 31.4

Some fungi can’t be classified into a division

because the sexual stage is never seen.

They’re called ‘Imperfect Fungi’

http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html

The organisms of the fungal lineage include

mushrooms, rusts, smuts, puffballs, truffles, morels, molds, and yeasts,

as well as many less well-known organisms …

Mushrooms, molds, yeasts, lichens & mycorhizae

are convergent ‘lifestyles’{phenetic groups}

that evolved independently {not phylogenetic lineages} ,

scattered across Zygomycota, Ascomycota & Basidiomycota


http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.htmlhttp://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html

… the sister group of animals

and part of the eukaryotic crown group

that radiated about a billion years ago …

They export hydrolytic enzymes that break down biopolymers{esp lignin in wood},

which can be absorbed for nutrition.

{fungi are aerobic; anaerobic bacteria can’t decompose lignin;

wood doesn’t decompose in anaerobic conditions, like the bottom of a lake}

Rather than requiring a stomach to accomplish digestion,

fungi live in their own food supply and simply grow into new food …

When one of the filaments contacts a food supply, the entire colony mobilizes

and reallocates resources to exploit the new food.

Should food become depleted,{sex, and then}sporulation is triggered.

Although the fungal filaments and spores are microscopic, the colony can be very large

with individuals of some species rivaling the mass of the largest animals or plants.


In 2000, scientists discovered http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html

the mycelium of one giant individual

of the fungus Armillaria ostoyae in Oregon

that is 3.4 miles in diameter and

spreads through 2,200 acres of forest,

equivalent to over 1,600 football fields.

This fungus is at least 2,400 years old and hundreds of tons in weight,

qualifying it as one of Earth’s oldest and largest organisms.

One fungus body constructed of

tubular filaments (hyphae)

was brought to our attention

when molecular techniques

were used to show that

it was extensive

(37 acres and an estimated

blue whale size of 110 tons.

The Michigan fungus clone

(Armillaria bulbosa)

grew in tree roots and soil.

{mycorrhizae = ‘fungus roots}


Size, Shape and Allometry ofhttp://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html

Imagine a cube of protoplasm w/ size = L.

Surface

Surface

Surface

Surface

Supply

Surface

Surface

Volume

Volume

Volume

Volume

Demand

Volume

Volume

L

6

1

1

L

6xL2

The ratio = = 

If L = 1, =

L3

8xL

L

If grows to 8xVolume w/ tubular shape,

34

= = 4.25

8

If L = 2, = =

A Sphere minimizes , a Thread maximizes it.

2 L

If grows to 2xL = 8xVolume w/ same cubic shape,

6x4

8

6xL2

= 3

L3

Metabolic demands depend on Volume = L3.

Exchange Surface to supply those demands = 6xL2.


… hypha of a zygomycete … http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html

… many nuclei present.

Many other fungi have septations that devide the hyphae into compartmentsCopyright © M. Blackwell 1996.

But, of course, there is

conflicting data!

Molecular phylogenetic analyses of the mitochondrial ADP-ATP carriers:

The Plantae/Fungi/Metazoa trichotomy revisited.Loytynoja A, Milinkovitch MC. 2001. Proc. Nat Acad Sci USA 98:10202-10207.

Fungi are characterized by non-motile bodies (thalli)

constructed of elongating walled filaments (hyphae),

a life cycle with sexual and asexual reproduction,

usually from a common thallus,

haploid thalli resulting from zygotic meiosis,

and heterotrophic nutrition.

The … wall components are chitin … and glucans …

… Fungi … share some characters with animals

such as chitinous structures,

storage of glycogen,

and mitochondrial UGA coding for tryptophan.

The branch uniting the fungi and animals

is well-supported from 18S rDNA sequence analysis,

and also has been supported with studies of …

proteins: alpha- and beta-tubulin and actin


1. plasmogamy: fusion of cytoplasm http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html

w/ multiple haploid heterokaryotic state

2. karyogamy: fusion of nuclei,

recombination and

immediate meiosis

‘fungi imperfecti’

when conditions good haploid mycelium

just grows

& clones self via

asexual spores

Generalized life cycle - Fig 31.3 - mostly in hapliod (or multiple haploid) state

sex - recombination

triggered by deteriorating environment

http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html

Prior to mating in sexual reproduction,

individual fungi communicate with other individuals chemically via pheromones.

In every phylum at least one pheromone has been characterized,

and they range from sesquiterpines … to oligopeptides….


Fig 31-5.http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html Chytridiomycota (chytrids).

The branched hyphae of Chytridium

expose a large surface to the surrounding medium,

from which the organism absorbs nutrients.

Chytrids are the only fungi with a flagellated stage,

the zoospore.

1. Chythrids

The chytrids are mainly aquatic.

Some are saprobes; others parasitize protists, plants, and animals.

Parasitic chytrids may be contributing to

a worldwide decline in the number of amphibians.

In the past decade, molecular systematists

comparing the sequences of proteins and nucleic acids uncovered strong support

for including the chytrids with the fungi as a monophyletic branch

of the eukaryotic tree

Other key fungal characteristics of chytrids are

cell walls made of chitin and

some key enzymes and metabolic pathways that are common among fungi

but are not found in the so-called funguslike protists (slime molds).


2.http://phylogeny.arizona.edu/tree/eukaryotes/fungi/fungi.html Zygomycota - Fig 31.7

A common zygomycete is black bread mold,

Rhizopus stolonifer

http://www.pacificcoast.net/%7Emycolog/CHAP3b.htm

…a petri dish containing nutritive agar medium. Two sexually compatible strains

of Phycomyces blakesleeanus were inoculated

on opposite sides of the plate.

The mycelia spread across the surface.

Where they met, a line of zygosporangia

with spiny appendages formed. 

Complementary mating types:

genetic compatibility means

different genotypes.

‘Safe Sex:’ mycelium is aseptate

except to wall off area of plasmogamy.

The zygosporangia, for which zygomycetes are named,

are resistant to freezing and drying and are metabolically inactive.

When conditions improve, the zygosporangia release genetically diverse

haploid spores that colonize the new substrate.

Fig 31-8.

Pilobolus aiming its sporangia. This zygomycete decomposes animal dung.


Asexual ‘naked’ spores (= conidia = ‘dust’) formed at ends of hyphae;

produce Sexual spores in saclike asci

http://www.perspective.com/nature/fungi/ascomycota.html

Truffles & morels - mostly mycorrhizal with tree roots

 half the 60k species live as lichen partners; some yeasts

Sacchromyces cervisiae, an ascomycete

is most important domestic fungus Fig 31.15

Bakers & brewer’s yeast are different domestic strains:

anaerobic fermentation of sugars to alcohol and CO2.

3. Ascomycota - sac fungi - Fig 31.10


… morels at ends of hyphae; and false morels are … related to the cup fungi Ascomycetes.

Their spores are produced inside a special cell called the ascus …

There have been numerous attempts to grow morels indoors

because of their value and the challenge of finding them.

Neogen, a Michigan biotechnology company,

patented the first successful commercial cultivation method in 1981.

The process they developed fools the fungus into producing morels

by starving the sclerotium (knot of filaments produced

when growth conditions are bad) …

{again - sex, recombination and dispersal when local environment deteriorates}

Truffles are formed by fungi that are partners (ectomycorrhizal) with certain trees.

… the right trees must be present. You will not find truffles under maples,

for instance, because maples do not form ectomycorrhizae.

3. Ascomycota


http://www.perspective.com/nature/fungi/agaricus.html at ends of hyphae;

The Agaricus family

includes the best known mushroom in the US:

The white buttons sold generically as "mushrooms"

are a cultivated variety of Agaricus

The "wild" Crimini and Portabella mushrooms

are also cultivars of this species.

4. Basidiomycota: Fig 31.10

Club fungi w/ long-lived dikaryotic mycelia

and transient diploid stage = ‘little pedistal’ = Basidium

= mushroom


The at ends of hyphae;leaf-cutting ants

of Central and South America

create their food supply by forming

a mutually beneficial association with certain fungi.

They grow these fungi on gardens created from … leaves.

The ants cannot digest cellulose …In the cell walls of leaves, but the fungus can. … the fungus converts the cellulose into carbohydrates. The ants then eat the fungus.

bromatia (inflated hyphal tips)

of the cultivated fungus,

Leucoagaricus gongylophorus (Agaricales). 

These are the main food of the ants.

http://www.pacificcoast.net/%7Emycolog/chapter16.htm

4. Basidiomycota

The ants house the beneficial fungus in their nests,

supply it with leaves, and remove any invading fungi.

The fungus benefits from a guaranteed food supply

and the elimination of competing fungi.

{Note assertion that cultivated foods benefit from cultivation}

Neither the ants nor the fungus is found separately in nature.


+5. ‘ at ends of hyphae;Imperfect Fungi’ - can’t be classified

till they show their private parts!

Around 25,000 additional fungi

Members include

Trichophyton (Athlete's foot),

Candida albicans

("Yeast" infections).

Penicillium (Penicillin),


vaginal yeast infections at ends of hyphae; are caused by Candida albicans,

which, along with a few types of bacteria,

are normally present in small numbers in your crotch.

sometimes the yeast multiply rapidly and take over,

causing a full-fledged yeast infection,

antibiotics are probably the leading cause of vaginal yeast infections …

say you take an antibiotic to cure your sinus infection.

the antibiotic kills the unwanted bacteria in your sinuses,

but can also kill the "good" bacteria in your crotch,

upsetting the balance of your vaginal ecosystem,

allowing the yeast to take over.


Ergosterol at ends of hyphae;, the principal sterol

in the fungal cytoplasmic membrane,

is the target site of action of

amphotericin B and the azoles.

Amphotericin B … binds irreversibly to ergosterol,

resulting in disruption of membrane integrity …

The azole drugs inhibit synthesis of ergosterol

through an interaction with

the … enzyme 14 alpha demethylase,

necessary for the conversion of lanosterol to ergosterol.

http://www.aber.ac.uk/biology/research/skellygrp/azole.htm

… flucytosine, an oral fluorinated pyrimidine,

inhibits both fungal DNA and RNA protein synthesis.

Flucytosine is a synthetic agent chemically related to fluorouracil and floxuridine, … It is converted to 5-fluorouracil (5-FU) which inhibits thymidylate synthetase. Thymidine is required for DNA synthesis. Vertebrate cells have little of the enzyme{cytosine deaminase }required to convert flucytosine to the active antimetabolite

http://www.niaid.nih.gov/dmid/meetings/mycology94/fungal.htm

… the five licensed antifungal drugs …

the most important and commonly used agents

against the systemic fungal diseases are

flucytosine, amphotericin B and the three azole drugs, ketoconazole, itraconazole, and fluconazole.


One type of ascomycete, Claviceps purpurea , at ends of hyphae;

forms purple structures called ergots on rye.

If diseased rye is inadvertently milled into flour and consumed,

poisons from the ergots cause gangrene, nervous spasms,

burning sensations, hallucinations,

and temporary insanity.

One of the hallucinogens that has been isolated from ergots

is lysergic acid, the raw material from which LSD is made.

Some of the fungi that attack food crops are toxic to humans.

For example, some species of the mold Aspergillus

contaminate improperly stored grain and peanuts

by secreting compounds called aflatoxins,

which are carcinogenic.


Fig 31.15: Fungus mostly ascomycetes at ends of hyphae;

- green partner green algae or cyanobacteria


mycorhizae at ends of hyphae; "fungus roots" Fig 31.18&19;

about 95% of plants have mycorrhizal symbionts

http://daphne.palomar.edu/wayne/ww0504.htm#soil

The beautiful, red, fly agaric mushroom

(Amanita muscaria) is unmistakable with

its bright red cap covered with white scales.

It contains the toxic alkaloid, muscimole,

http://www.pacificcoast.net/~mycolog/chapter17.htm

ectomycorrhizas (upper)

and mycelial strands (lower)

of Amanita muscaria on Pinus strobus

http://www.pacificcoast.net/~mycolog/chapter17.htm

seedlings of Douglas fir

with and without

ectomycorrhizal partners.

Mycorrhizal symbioses: two types are recognized:

1. In ectomycorrhizae the hyphal threads coat the tips of tree roots.

Many large forest fungi form ectomycorrhizal partnerships,

both truffles with underground fruiting bodies and

fungi with the umbrella-shaped fruiting bodies known as mushrooms.


mycorhizae at ends of hyphae; Fig 31.16; see pg 702;

about 95% of plants have mycorrhizal symbionts

2. Endomycorrhizae are the most common type of mycorrhizal symbiosis {Arbuscular Mycorrhizae - AM }. Endomycorrhizal fungi do not coat the root.

Only a few hyphae spread across the root's surface … enter into the root cells.

This type of fungus usually produces single spores in the soil for reproduction,

not large fruiting bodies {notmushrooms}.

Fig 31-19. An experimental test

of the benefits of mycorrhizae.

The soybean plant on the left lacks mycorrhizae.

Mycorrhizal symbioses: two types are recognized:


Abstract: at ends of hyphae;Fossilized fungal hyphae and spores

from the Ordovician of Wisconsin

(with an age of about 460 million years)

strongly resemble modern arbuscular mycorrhizal fungi

(Glomales, Zygomycetes),

These fossils indicate that Glomales-like fungi

were present at a time when the Land flora

most likely only consisted of plants on the bryophytic level. …

these fungi may have played a crucial role in the colonization of Land by plants,… the fossils support molecular estimates of fungal phylogeny that place

the origin of the major groups of terrestrial fungi

(Ascomycota, Basidiomycota, and Glomales) around 600 million years ago.

Glomalean fungi from the Ordovician.Redecker et al.

SCIENCE 289: (5486) 1920-1921 SEP 15 2000


Arthrobotrys Fig 31.12, at ends of hyphae;

- snares nematodes

Some fungal spores

are marketed as

biocontrol agents

- insecticides


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