BIS2C - Amoebozoans/Fungi

multinucleate body form

body type that forms by karyokinesis (without cytokinesis) OR by fusion of cell membranes

plasmodial slime molds

individual motile, diploid cel that undergoes nuclear division to form a single, enormous multinucleate cell (plasmodium) — cool, moist environment

under harsh conditions, can make a diploid resting stage or meiosis to make spores on fruiting bodies

what happens after spores germinate on plasmodial slime molds?

spores germinate to make swarm cells (can be asexual or fuse to make new diploid cell)

cellular slime molds

ameboid stages are called myxamoebae and are haploid

what happens when food runs out for cellular slime molds?

myxamoebae come together to make “slug” body when a signal is sent out

slug travels to new habitat and turns into a spore-dispersing body with a stalk (spore —> ameobae)

how can myxamoebae reproduce?

1. binary fission

2. form cysts that fuse to make diploid stages that then undergo meiosis

slug formation in cellular slime molds

can be made of one genotype or many genotypes

uniclonal slugs travel further but larger slugs travel further

synapomorphy of fungi

absorptive nutrition, chitin in cell walls

why is wood so stable?

cellulose, lignin and hemicellulose make up woody plants

cellulose made of beta 1,4-linked glucose units which is hard to break

hemicellulose tough

lignins are very tough, rigid, and resistant to decay

who can break down cellulose?

termites, cows, horses, koalas can digest cellular with help of unicellular euks and bacteria

ophryoscolex

fungi (using absorptive nutrition)

what composes the fungal body?

fungal body is called mycelium and is composed of many hyphae

features of hyphae

grow only at tips

secrete digestive enzymes at tips, so digest food in environment

why do fairy rings exist?

growing part of fungus (tips of hyphae) secrete digestive enzymes into the environment with many properties

• like hydrophobic compounds, nitrogen, mushrooms

brown rot fungi

can break down cellulose and hemicellulose but leaves lignin behind (in conifers)

white rot fungi

breaks down cellulose, hemicellulose, and lignin

in all trees

no fungi in the Carboniferous period

peat (partially decayed plant material) = C sink

formed when plants in swamps died; acidified swaps and decreased fungal abundance

bc no fungi, no decomposition of peat and plant matter became fossil fuels

what is a novel use of hyphae in capturing prey

some hyphae form a ring that can swell after absorbing water to capture nematode prey

saprobes

decomposers; fungi are important in nutrient cycling

fungi in composting

they break down cellulose and lignin making more organic material available to bacteria

different species of fungi present during mid and high temperature phases of composting (heat is released during decomposing)

what is the preferred complexity in the food sources for fungi?

prefer intermediate nutrient complexity (like monosaccharides, starch, cellulose)

fungi in bioremediation (mycoremediation)

fungi play important roles in cleaning up polluted sites by targeting pollutants like PCBs)

microsporidia

intracellular parasites with no mitochondria (infect immunocompromised humans)

their spores can invade cells by injecting cytoplasm in host and reproducing there

chytrids

non-monophyletic group that is the only fungal lineage with swimming spores and gametes

play a role in amphibian decline

mycorrhizae

lineage that involved in symbioses with land plants (increases surface area for nutrient absorption in exchange for carbs)

benefits plant gets from mycorrhizae

protection from root pathogens

increased longevity of fine roots

protection from heavy metals in soil

linkages between plants (common mycorrhizal network)

what are the two body forms of fungi?

mycelium (feeding, composed of hyphae)

reproductive fruiting structure (releases spores, often a “mushroom”)

where is the main morphological difference between fungi found?

in their fruiting body

aseptate vs septate hyphae

asepate hyphae do not have septa (walls) that prevent the free flow of cytoplasm

plasmogamy + when it evolved

fusion of cytoplasm

plasmogamy preces karyogamy (evolved before zygomycota)

karyogamy

fusion of two haploid nuclei, resulting in a dikaryon stage

general life cycle of fungi

variable life cycle for fungi

dikaryon

synapomorphy of dikarya

it is:

• two, genetically distinct haploid nuclei in each cell

• individual cells do not act as gametes (no real gametic stage)

• hypal fusion with nuclei acting as gametes

ascomycota

largest group of fungi (2/3 of species) — many yeasts and molds

has ascus (its diagnostic spore structure)

many types of fruiting bodies (many cup-like)

asexual OR sexual reproduction

ascus

sac-like stage with 8 spores (internal spores) called ascospores

ascomycota life cycle

slide 20 lecture 22

fruiting body made of dikaryotic and monokaryotic hyphae

ascomycota fruiting bodies

many shapes, including edibles like morels and truffles

asexual reproduction in fungi

some fungi produce asexually via mitospores (conidia)

pinching off cells at tips of hyphae to start a new mycelium

molds

ascomycetes that lack sexual reproduction in life cycle

only using mitospores

yeasts

unicellular fungi that lack fruiting bodies

ex. are used in making bread and wine (releases CO2)

basidiomycota

2nd largest group of fungi; diagnostic spore structure is basidium (with external looking spores)

which structure on the fruiting body can tell you its a basidiomycota?

gills

basidia and basidiomycota extend out from the surface of a gill

which basidiomycota don’t have fruiting bodies? what example did we discuss in class?

smuts and rusts

ex. huitlacoche (smut fungi) — a delicacy that used in food

examples of enclosed fruiting bodies

puffballs and truffles

evolved several time within basidiomycota and ascomycota (gills in the center)

subterranean fruiting body

probably evolved in response to dry conditions

mostly dispersed by animals (humans dig up truffles)

lichens

symbiosis between ascomycota (the mycobiont) and cyanobacteria or algae (photobiont) with basidiomycete yeast in upper crust protecting lichen with vulpanic acid

fungi are obligated to their photobiont (but not the other way around)

the symbiotic relationship present in lichens

ascomycota gets sugar

provides shelter, moisture, mineral

what forms the body of the lichens?

formed from fungal hyphae

how can reindeer feed on lichens?

have a unique starch called lichenin

reindeer have lichenase to break starch down to glucose

fungi as parasites — plants

have a large econ impact as they are common plant parasites

methyl bromide and fungi

used methyl bromide as a gas fumigant to protect crops from fungi BUT depletes ozone so being phased out

bad for strawberries

rice blast disease

causes lots of loss on rice crop

treatment options limited as fungi spreads quickly and develops resistance

Claviceps

invades grasses like rye

eating infected rye causes St. Anthony’s Fire

St. Anthony’s Fire

burning of limbs associated with severe vasocontriction

but can be used to stop migranes, stop bleeding after childbrith, and treat Parkinson’s

white nose syndrome

caused by Pseudogymnoascus destructans

decimate bats throughout the US as it disrupts hibernation and uses vital fat reserves

Cordyceps

attach to arthropods and take control of their muscles to modify their behavior

makes anthropod into a spore dispersing structure

psilocybin

hallucinogens

competes with serotonin and causes hallucinations

aflatoxin

caused by a fungi that commonly infects food sources and can have lethal effects on animals (like liver cancer)

aflatoxin and soy sauce

close relative of A. flavus, A. oryzae, is used to flavor soy sauce

may be correlated with higher rates of cancer in E/SE Asian countries

disease with inhaled spores

histoplasmosis (caused by inhaling conidia + grows as yeast) and bagpiper’s lung

ringworm

fungal skin infection