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Algae, Fungi And Mosses > Chytridiomyctoa > Flashcards

Chytridiomyctoa Flashcards

1
Q

Chytrids diversity

A

Over 900 species in 5 orders

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2
Q

Chytrids habitat

A

Mostly grown aerobically in soil, mud or water, some species inhabit estuaries and others the sea.

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3
Q

Life styles of Chytrids

A

Mostly saprotrophs: breakdown of materials that decompose plants and animals

Parasites of terrestrial fungi, filamentous algae and diatoms or vascular plants

Pathogens of freshwater invertebrates like larval mosquitos

Obligate anaerobes: grow in rumen of herbivorous mammals and breakdown cellulose

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4
Q

How do Chytrids reproduce

A

Reproduce by zoospores with a single posterior flagellum except order Neocallimastigales which are multiflagellate

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5
Q

Chitin

A

Within cell walls of most chytrids species and Eumycota

Consists of chitin microfibrils

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6
Q

Phylum chutridiomycota can have what in their cell walls

A

Chitin and cellulose

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7
Q

Thallus morphology of Chytrids

A

Form of thallus is varied:

Holocarpic: within parasitic species-whole thallus is contained within the host cell, no differentiation into vegetative and reproductive parts. At maturity, the entire structure except cell wall which surrounds it, is converted into reproductive units (zoospores, gametes or resting sporangia)

Eucarpic: Thallus differentiated into reproductive (sporangia and resting sporangia) and vegetative organs (rhizoids, rhizomycelium)

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8
Q

Mono centric forms include:

A

Endo biotic: entire thallus inside host cell

Epibioitc: rhizoids inside host cell and sporangium external

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9
Q

Eucarpic thalli have one or several sporangia: ______ vs ______

A

Mono centric

Poly centric

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10
Q

Inoperculate Chytrids

Operculate chytrids

A

Sporangium forms a discharge tube which penetrates host cells

Tip of discharge tube breaks open at a like of weakness and is seen as a special cap or operculum after discharge

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11
Q

Two features of taxonomic importance for chytrids

A

Flagellar apparatus

Micro body lipid globule complex

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12
Q

Whiplash flagellum on chytrids is made up of what parts

A

Axoneme: made up of nine doublet pairs of microtubules surrounding two central microtubules

Kinetosome: at the base generates flagellum

Remainder of second kinetosome in some suggests that ancestors of chytridiomycota may have had biflagellate zoospores

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13
Q

Movement variation of chytrids

A

Period of zoospore movement varies:

-swim for minutes to hours -> Amoeboid crawling
-prior to germination: zoospore rests and encysts->flagellum contracts or casts off
-zoospores encysts on the host surface (Holocarpic groups): cytoplasmic contents of zoospore injected into host

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14
Q

When are fossils of chytrids found and what did they look like

A

Devonian age: 400mya
-clusters of Holocarpic endobiotic thalli resembling the modern chytrids found inside algae cells-> chytrids were aquatic parasites

-fungi probably emerged from water, as did plants and vertebrates

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15
Q

Largest order of chytrids

And it’s lifestyle

A

Order Chytridiales (50%)

Parasitic on fungi, algae, protozoa

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16
Q

How can you bait chytrids

A

Baited in crude culture by floating baits (cellophane, hair, shrimp exoskeleton, booed grass leaves and pollen) on surface of water overlying samples of soil, mud or pieces of aquatic plant material

17
Q

Asexual reproduction of Chytridiales

A

-Haploid, uniflagellate zoospores swim to substrate
-zoospores attach producing rhizoids: delicate hypha-like filaments with protoplasm but without nuclei
-zoospore develops into sporangium
-multinucleate protoplasmic sporangium cleaves at operculum to release zoospores
-zoospores swim away completing asexual cycle

18
Q

Haploid zoospores of Chytridiales can also develop into ______

A

Sexual thalli
-rhizoids if compatible thalli come into contact
-protoplasm of each thallus streams towards point of fusion (plasmogamy)
-resting body is formed from protoplasts of each thallus, leaving them empty
-Karyogamy converts resting body into zygote

Zygote-> sporangium-> haploid zoospores released into water

19
Q

Synchytrium sp. causes what diseases and are what type of parasites

A

Potato wart
Black scab disease

Endobiotic, Holocarpic parasites of algae, mosses, ferns and flowering plants

Typically cause galls (hypertrophied growth) on the diseases parts

20
Q

Synchytrium resting winter sporangia and summer sporangia

A

In the spring, resting winter sporangia in decaying warts and soul germinate to realize haploid zoospores

Zoospores migrate in soil water (50mm or less) to infect epidermal cells of sprouting potatoes

Zoospores are short lived and then encyst infected host tissue in 1-2 hours

Host cells engage: Sori form inside host cells (warty galls)

Each sorus contains summer sporangia-> germinate to produce new haploid zoospores which reinfect susceptible tissue

21
Q

When do testing spores of Synchytrium form

A

Under conditions of stress (water shortage)

-zoospores fuse->diploid, biflagellate zygotes-> infect the host tissue to form resting sporangia

22
Q

Resting sporangium of Synchytrium remain viable how long?

How are the spores spread

A

40-50 years in soil

Resting sporangia spread in infected seed tubers, infected soil and equipment

23
Q

Order Neocallimastigales inhabit where?

A

Ruminant animals: aquire nutrients from plant-based food by fermentation in a rumen (specialized stomach) prior to digestion, principally through microbial actions

-rumen fungi inhabit the gastrointestinal tract of ruminants.
-microbes include bacteria, protozoa and 8% fungi by weight

These fungi are adapted for anaerobic conditions

24
Q

Gut or rumen fungi produce what?

A

Broad range of hydrolase enzymes and include the most active hemi cellulases that break down cellulose

Allows ruminant animals to break down cellulose

25
Q

Among these carbohydrate types, which is easiest to digest in which is the least?

Sugars, starches and pectin

Hemicellulose and cellulose

Lignins

A

Sugars first 95-100% digestibility
Cellulose second
Lignin only 0-20% digestibility

26
Q

What order of fungi has caused a decline in frog populations

A

Rhizophydiales

Batrochocytrium dendribatidis has cussed global amphibian decline

27
Q

How does order Rhizophydiales work to decline amphibian populations

A

-fungus invades top layers of skin cells and causes thickening of the keratinized layer
-disrupt breathing, balance of sodium and chloride ions in blood leading to heart beat irregularities and stopping
-zoospores swim out through a discharge tube (inoperculate chytrid) and the empty sporangia remain

28
Q

Amphibian chytrid life cycle

A

Spores swim towards frogs

Spores burrow into skin and develop into thallus

Mature fungus develops into sporangium

Spores released after 4-5 days

Infected frog died in 120 days

29
Q

_______ is the first chytrid fungus known to parasitize vertebrate animals

A

Batrachochytrium dendrobatidis (Bd)

30
Q

Why did Bd spread so quickly around the world

A

Human pregnancy tests developed using female frogs in 1930’s. Resulted in massive export of the frogs to labs around the world, to produce home pregnancy tests. Bd may have orijgnallt spread from lab to wild frogs through water the frogs were housed in.

31
Q

X. laevis (frogs used in pregnancy tests) have been exposed over a long enough euros to Bd that they have developed…..

A

Defensives against Bd chytridiomycosis

32
Q

Chloramphenicol

A

Antibiotic useful for the treatment of a number of bacterial infections used as eye ointment to treat conjunctivitis, may be a lifesaver for the amphibians

Infested frogs bathed in the solution recovered and became resistant to the killer disease: Chytridiomycosis

33
Q

Most true chytrids produce _____ mycelium

Water molds (Allomyces) makes ______ mycelium

A

Limited

Extensive

34
Q

Like the chytrids, water molds are the only members of the fungi in which _______ has been retained

A

Motility

35
Q

Summer sporangia characteristics

A

No thick cell wall
Not a resting spore-just produce more zoospores

36
Q

Chytrids help with cellulose and hemicellulose breakdown from what pH range

A

7-5

37
Q

A thick outer wall indicates what?

A

Resting spore!!! For winter survival

Algae, Fungi And Mosses (18 decks)

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