Exam 3 (lect 20,21, Flashcards
Fungi v fungi
F - in kingdom
f - studied by mycologists but not Fungi
Major euk characteristics unique to fungi
chitin in cell walls
ergosterol in cell membranes
spindle pole bodies
multi-nucleate cells
fungi and animal commonalities
no plastids
store food as glycogen (plants use starch)
plant and fungi commonalities
cell walls
fungal cell walls
multi-layered complex of diff molecules
CHITIN - key polysaccharide (rigidity)
fungal cell membranes
ergosterol (analogous to cholesterol in animal cell membranes)
ergo is primary target of anti-fungal drugs. does not keep osmotic potential of cell
polyenes like nystatin
anti-fungal drug
mode of action - ionophore (reversibly binds ions)
binds to ergosterol in fungal cell membranes
fungal infections prevalence
more prevalent in plants than animals
fungal cells nuclear division
unlike plants/animals, nuc envelope does not disintegrate ahead of mitosis
division occurs in nucleus and is organized by spindle pole bodies
spindle pole bodies - fungi
organize nuclear division
separate daughter
correct seaparation
fungal cells nuclei
individ cells typically contian multiple nuclei which move between cells
movement of nuclei
move between cells through septa
septa
partition that separate and defines one cell
allows nuclei and other cellular materials to move between
main parts of fungi
spores (asexual/sexual)
reproductive struct (sporangia)
body (in soil/water, biggest part)
fungal body - hyphae
thin thread-like filaments um
turgor pressure on rigid cell wall drives extension
osmotic potential drives water to tip
growth at tip!
spitzenkorper
collection of vesicles at hyphal tip
white tip, vesicles coming together
hyphal vesicles
contain enzymes and wall material
- fuse w membrane
- loosen wall
- add new wall materials to extend
hyphal branching
grow via extension and branching of hyphae
many hyphae = mycelium
hyphal fusion
allows growing mycelium to stay integrated physiologically
fusion - moves stuff across body, basis for fungal sex
tells self from non-self
external digestion
breakdown compounds outside of body export enzymes (cellulase) --> biopolymers (cellulose) --> monomers (glucose) --> back to fungi
fungi eating name
osmoheterotrophy
animals - phagoheterotrophy
advantages of hyphal growth
- high SA to vol ratio. Massive growth w/o diffusion limitation (do digestion close to surface)
- turgor-driven tip growth allows penetration into food sources
- Allows individuals to grow across patchy resources (integrate resources across body)
yeasts
unicellular growth (not hyphal)
growth pattern
NOT monophyletic (evolved multiple time independently)
advantage - rapid growth
yeast human importance
leavened bread, alcoholic bev
pathogens
dimorphic fungi
grow as hyphae or yeast depending on enviro conditions
dimorphic fungi examples
coccidiodes immitis - valley fever
histoplasma capsulatum - bat vectored, bud as yeast in lungs
candida albicans - yeast infections, diaper rashes, thrush
fairy ring ecology
outer stimulated zone (decomposing stuff, releasing nutrients) dead zone (weak parasite with grass roots, 0.5 water potential) inner stim zone (older area, fungi is decomposing, passive + to plant, necromass)
growth that makes fairy rings
radial growth
start from spores and radiates out in all directions
estimated to be decades to centuries old
compared to low resource enviro, ratio of hyphal branching to extension in high resource enviro is?
higher. put as much of body to maximize ability to get nutrients
indeterminate growth
no predetermined shape/size (mycelium)
as long as there are resources, they can grow indefinitely
oomycetes euk super group
stramenopila
cellular/plasmodial slime molds euk super group
amoebozoa
oomycetes hypahe
similar to fungi
cont cytoplasm, growth from tips, enzyme secretion, specialized struct like haustoria (pathogens)
haustoria
oomycetes like fungi
projection from hyphae into tissue of host, absorb nutrients from it
oomycetes spores
similar to fungi oospores (sexual spores) zoospores (asexual spores) chlamydospores (asexual resting spores) asexual reproduc via spores means they can spread easily and rapidly increase inoculum (struct for inoculation)
chlamydospores
oomycetes
asexual resting spores
thick walled, resist harsh enviro cond
germ when better environmental conditions
oomycetes plant pathogens
like fungi
downy mildew, damping off (JC hypoth), potato blight, sudden oak death
diff in oomycota from fungi
- lack chitin (cellulose instead!)
- zoospores are diff. Have 2 flagella (regular whiplash and tinsel)
- all vegetative are diploid (2n). like humans but unlike fungi
relative sexuality
oomycetes
isolate can make antheridia with one mate and oogonia with another
why slime molds studied by mycologists?
morphological similarities (spores and heterotrophy) same habitats
slime mold differences from fungi
vegetative (growing) state is NOT hyphae or yeast BUT amoeba or plasmodium
when present, flagellated have 2 flagella (like oomycota)
phagocytosis (feed by ingestion NOT absorption, not like oomycota)
plasmodial slime mold
most visible stage is plasmodium
not single cell but continuous cytoplasm with many nuclei (no partition like in fungi)
moist enviro
can form sporocarps
sporocarps
plasmodia can organize to form
where spores are produced
sclerotium
unfavorable condition
plasmodial slime mold
plasmodial slime mold intelligence
able to coordinate growth to find best resources
cellular slime molds
spend most of lifecycle as amoeba
moist habitats
eat bacteria, yeast cells, fungal spores, algae
ingest food and digest internally
pseudoplasmodium
cellular slime mold
when amoeba run out of food, aggregate to form this
pseduo b/c still individual cells
involves cellular signaling in response to stress (cAMP)
slug
cellulose sheath over aggregation
cellular slime mold
sleek, shiny outside layer
migrates toward location with optimal spores dispersal (higher light, more oxygen, drier)
SOROcarp
cellular slime mold
slug differentiates to form this fruiting body
stalk and spore mass
stalk cells die, spore mass cells live, form cells, and germinate as amoeba
cellular slime mold cycle
singular, pseudoplasmodium, slug, SOROcarp
farming
actively cultivating organism that will be consumed by farmer
farmer fungi
dictyostelium
farmer fungi traits
dictyostelium clones that have bacteria in their sori
~1/3 of samples
is farmer lifestyle random?
experiment that used antibiotics and then re-tracked bacterial growth
clones would reform their bacterial assoc follwing antibiotics and non-farmers remained non-associated
lifestyle is actively pursued by some
NOT accidental
benefit of bacteria in farming
in enviros where bacteria are absent, farming is beneficial because it brings bacteria with them
when bacteria are present, farmers don’t grow as much
is farming an overall good strategy?
ensured food source at next location and may benefit from associating with more edible bacteria –> evolutionarily stable strategy
farmer clones develop fruiting bodies before all bacteria are exhausted BUT non-farmers wait until all bacteria are exhausted
potato blight
oomycete
phytophthora infestans
downy mildew
plasmopora
oomycete
how many fungal species have been described
120,000 described taxonomically
hawksworth 1991 fungi estimation
estimation of total fungal species based on plant to fungal ratio British isles, US products, sweden, alpine sedge. all from high N lat. biomes no tropical locations used
fungal estimates based on soils
black spruce forests
Fungal:plant ratio is 17:1 based on forest soils from interior alaska. Estimates at least 6 million fungi species
global diversity and geography of SOIL fungi
Plant:Fungal species ratios
both highest at equator
decline in richness is steeper for plants in temperate and boreal regions
more F at high lat and more P closer to equator
