Transcript Welcome to Biology 122

Mycetozoa
Domain Eukarya
Kingdom Protista
Phylum Mycetozoa
Looking Back at Bio 115
The Organism as a Unit of Life
Cellular Structure (cell = unit of life)…one or many!
Metabolism = Homeostasis (PSN, Resp, N2fix, ferment, etc.)
Growth = irreversible change in size
Reproduction…failure = extinction
Acclimatization-short term responses = behavior
Adaptation-long term responses = evolution
Lumpers
Shifting Kingdoms
Plantae
Fungi
Protista
Splitters
2
3
5
6
8
Bacteria
Bacteria
Bacteria
Bacteria
Bacteria
Archaebacteria
Archaebacteria
Archaebacteria
Archaebacteria
Archaebacteria
Archezoans
Archezoans
Archezoans
Archezoans
Archezoans
Euglenoids
Euglenoids
Euglenoids
Euglenoids
Euglenoids
Chrysophytes
Chrysophytes
Chrysophytes
Chrysophytes
Chrysophytes
Green Algae
Green Algae
Green Algae
Green Algae
Green Algae
Brown Algae
Brown Algae
Brown Algae
Brown Algae
Brown Algae
Red algae
Red algae
Red algae
Red algae
Red algae
Slime Molds
Slime Molds
Slime Molds
Slime Molds
Slime Molds
True Fungi
True Fungi
True Fungi
True Fungi
True Fungi
Bryophytes
Bryophytes
Bryophytes
Bryophytes
Bryophytes
Tracheophytes
Tracheophytes
Tracheophytes
Tracheophytes
Tracheophytes
Protozoans
Protozoans
Protozoans
Protozoans
Protozoans
Myxozoans
Myxozoans
Myxozoans
Myxozoans
Myxozoans
Multicellular
Animals
Multicellular
Animals
Multicellular
Animals
Multicellular
Animals
Multicellular
Animals
Extant
How Many Kingdoms?
Protista
refined
8
Protista appears
Still needs refining!
5
3
Extinct
2
1
Original Cell
Mycetozoans
•
“True and Cellular Slime Molds”
•
Somewhere between protists and fungi

Predatory amoeboid feeding upon bacteria, usually in decaying
material

Engulfing feeding

Reproduction via spores
•
500 species
•
Two Major Classes:
1.
2.
Myxogastrea (True slime molds: Physarum)
Dictyostelea (Cellular slime molds: Dictyostelium)
Physarum polycephalum
True Slime Mold
Haploid (1N) spores
germinate in rotting
vegetation
Flagellated gametes emerge
and undergo syngamy
Diploid (2N) zygote
amoeboid cell feeds on
bacteria
Mitosis without cytokinesis
makes multinucleate
plasmodium
Cytoplasm migrates by
streaming
Develops into fruiting body
undergoing meiosis to
make haploid spores
http://botit.botany.wisc.edu:16080/images/332/Slime_molds_M_Ac_sl_so/Physarum_folder/Physarum_plasmodium_I_TJV.gif
Physarum polycephalum
True Slime Mold
Food
Vacuoles
Nuclei
http://bic.usuf1.usuhs.mil/Mark/Images/OgiharaEM01.jpg
This portion of the
plasmodium is showing the
amoeboid movement of the
cytoplasm.
The plasmodium engulfs
bacteria by endocytosis into
food vacuoles for digestion
The plasmodium is
multinucleate, and each
nucleus is diploid (2N).
Physarum polycephalum
True Slime Mold
QuickTime™ and a
Photo - JPEG decompressor
are needed to see this picture.
The plasmodium with all of
those nuclei and food vacuoles,
etc. shows amazingly active
cytoplasmic streaming shown
in this movie.
The movement involves actinmyosin interactions between
microfilaments of actin and
myosin proteins bound to
organelles.
The movement relies upon
Ca2+ and ATP availability.
http://botit.botany.wisc.edu/courses/img/Botany_130/Movies/Slime_mold.mov
Physarum polycephalum
True Slime Mold
Looking at this sporangium,
can you figure out how the
specific epithet was inspired?
Sporangium
Sporangiophore
Spores
http://www.botany.hawaii.edu/faculty/wong/Bot201/Myxomycota/Physarum_Sporangium.jpg
http://www.bioimages.org.uk/MMWSt/PixM.7xs/2000/00-10/00-10-17/00J17E+E.jpg
Physarum polycephalum
True Slime Mold
Spore
Zygote
Gametes
http://www2.una.edu/pdavis/physamb.jpg
The spores germinate,
releasing flagellated gametes.
The gametes unite in syngamy.
The resulting zygote is
amoeboid and begins feeding.
Mitoses without cytokinesis
enlarges the multinucleate
zygote into a full plasmodium.
Tipula oleraceae or T. paludosa
Adults resemble mosquitoes
because they are indeed relatives.
adult
Adults generally do not feed and
live for only a few days.
eggs
The larval stages are aquatic in
some species or lawn soil dwelling
in other species.
adult
larva
pupa
http://whatcom.wsu.edu/cranefly/faq.htm
Life Cycle of Physarum polycephalum
isogametes
swarm cells
mitosis
gametes
zygote
gametangia
differentiation
asexual
reproduction
mitosis
plasmodium
SYNGAMY
Gametophyte
differentiation
mitosis
germination
1N 2N
germination
mitosis no cytokinesis
differentiation
Sporophyte
differentiation
sporangium
spores
mitosis
sporocyte
MEIOSIS
myxamoebae
4 meiospores
This is basically the gametic shortcut…
spores become gametes… if the mitosis
of myxamoebae is not considered
equivalent to the production of a
multicellular gametophyte.
sporocyte
cytokinesis
sporangium
Dictyostelium discoideum
Cellular Slime Mold
This is the spore produced by
the sporangium.
Actin rods extend the length of
the spore.
It is released into the wind and
carried to hopefully-better
environments.
There it germinates to produce
amoebae.
http://www.rinshoken.or.jp/org/EM/spore.jpg
Dictyostelium discoideum
Cellular Slime Mold
The amoebae feed upon
bacteria.
When the bacterial supply is
gone, one amoeba produces
cAMP.
This signals others to join
together to form a multicellular
pseudoplasmodium (“slug”).
http://www.nigms.nih.gov/research/images/dicty.jpg
Adenine
NH2
N
OO
P O
O O
O
N
N
N
Ribose
OH
http://dicty.cmb.nwu.edu/chisholm/chisho2.jpg
http://www.biologie.uni-hamburg.de/b-online/d27_10/agg290.jpg
Dictyostelium discoideum
Cellular Slime Mold
http://www.axxon.com.ar/zap/208/MohoMucoso.jpg
The pseudoplasmodium moves
on a slime trail seeking more
bacteria.
If bacteria are not found, the
plasmodium differentiates into
sporangiophore and
sporangium.
http://csep10.phys.utk.edu/krogh_instructorCD/biology/ImageBank/Unlabeled/CH20/uFG20_10.jpg
Dictyostelium discoideum
Cellular Slime Mold
The amoebae feed upon
bacteria.
When the bacterial supply is
gone, one amoeba produces
cAMP, signalling the others to
join together to form a
multicellular
pseudoplasmodium (“slug”).
The slug moves on a slime trail
seeking more bacteria.
http://www.bio.ic.ac.uk/research/tps/images/fig4.gif
If bacteria are not found, the
plasmodium differentiates into
sporangiophore and
sporangium.
The spores are shed to the
wind to disperse the species.