Protozoa (Protists) & Pluricellular Myxozoa Flashcards
- Classification/systematics - terminology - key characteristics - reproduction - life cycles
Kingdom Protozoa/Protista
- Phylum Mastigophora (flagellates)
- Phylum Apicomplexa
- Phylum Ciliophora (ciliates)
Kingdom Animalia
- Phylum Cnidaria (Myxozoa)
Phylum Mastigophora
flagellates
Phylum Ciliophora
ciliates
Phylum Cnidaria
Myxozoa
- parasitic jellyfish
- obligate parasite
- has 2 host life cycle that has 2 different spore forms produced
- have polar capsules
Protozoa
- classified by locomotion
- unicellular
- eukaryotic
Microspora
- not protozoans!
- sister to fungi
What do Apicomplexa and Ciliophora have in common?
Both are Alveolates under Subkingdom Protozoa
Phylum Euglenozoa
- Excavates
- include diplomonads & kinetoplasts
- unicellular organisms in domain Eukaryota
diplomonads
- parasitic flagellates
Amoebozoa
- protists with pseudopods
Stramenopiles
- Heterokonts (algae)
- Oomycetes (water molds)
Unikonts
- amoebozoa
- opisthokonts (fungi & animals)
Excavates
- amitochondriate flagellates
- amoeboflagellates
- Euglenozoa
Alveolates
- ciliates
- apicomplexans
- dinoflagellates
Cercozoa
- amoeboids & flagellates
- feed by means of pilose pseudopods
Protozoa
- single-celled eukaryotes
- free-living or parasitic
- “first and animal-like” implies kinship with animal (metazoans)
protist
- eukaryotic organism that has cells with nuclei and is not animal, plant or fungi
- includes algae, slime molds and dinoflagellates
- high-level classification of eukaryotic microorganisms
Zoite
- little creature
- prefixes added to spite to denote a portion of the life history
sporozoite
infective form
trophozoite
form which feeds and grows
tachyzoite
form which divides rapidly
bradyzoite
form which divides slowly
merozoite
many
protozoa (protists)
- unicellular, eukaryotic ‘animals’
- nucleus, ER, mitochondria, Golgi body, lysosomes
- anaerobic or aerobic
- absorbs nutrients or have a ‘pseudo-mouth’
- feeds on bacteria, other protozoa, organic matter or tissues of host
key characteristics of protozoa
- many are part of normal microbiota
- do not cause disease
- locomotion via pseudopodia, flagella, gliding movements or cilia
- asexual repro = large exposure = large damage
- hosts
- host specific or broad spectrum
- zoonotic aka non-host specific
- chronic infections; immunity
- forms cysts
Protozoa - Asexual Reproduction
- binary fission, budding, schizogony/multiple fission (merogony)
- asexual repro = short generation time & quick turn-around
Schizogony (merogony)
- exponential increase in numbers
- destruction of host cells in proportion to infection
- stops after a fixed number of repetitions
Protozoa - Binary Fission
- most common form of repro in prokaryotes
- also occurs in some single-celled eukaryotes
- e.g. ciliate Paramecium
Protozoa - Schizogony (Merogony)
- characterized by multiple divisions of nucleus and cell
- common in many apicomplexans
- e.g. Merocystis kathae In scallops (very pathogenic)
Intermediate host
- part of asexual reproduction life cycle
- e.g. Merocystis kathae in scallops
- scallops are intermediate hosts
Protozoa - Sexual Reproduction
- gametogeny or sporogony
- merozoite becomes a macrogametoyte (macrogamont) and then a macrogamete or micro gametocyte (microgamont) and then several microgametes
- microgamete fertilizes a macrogamete -> zygote
- a wall forms around zygote -> becomes an oocyst
- definitive host: Merocystis kathae in common whelk (sea snail) (not pathogenic)
Definitive host
- part of sexual reproduction life cycle
- e.g. Merocystis kathae in common whelk (sea snail)
- sea snails not harmed
- not pathogenic
Protozoa - flagellates
- subphylum: Mastigophora
- locomotion: by pseudopodia and/or flagella
- order: Kinetoplastorida and Diplomonadorida/Trichomonadorida
Kinetoplastorida
- haemoflagellates
- parasites of the blood
- generally transmitted by biting insects
- e.g. Trypanosoma cruzi
Diplomonadorida/Trichomonadorida
- flagellates
- predominantly of the intestines
- e.g. Giardia, Spironucleus, histomonas, tritrichomonas
Protozoa - Ciliates
- Phylum: Ciliophora
- locomotion: by cilia
- e.g. Balantidium sp. (pathogenic)
Balantidium coli
- parasitic species of ciliate (alveolate)
- only member of ciliate phylum known to be pathogenic to humans
- also found in pigs and other mammals aka zoonotic
- asymptomatic in pigs
- transmission: contaminated water
Protozoa - Apicomplexa
- Phylum: Apicomplexa
- locomotion: gliding
- life cycle: largely intracellular
- sexual and asexual phases
- Order: Eucoccidiorida, Piroplasmorida, Haemosporida
Eucoccidiorida
- parasite of epithelial cells
- sexual and asexual repro occurs in epithelial cells
- e.g. Eimeria/Goussia, Isospora, Cystoisospora, Hepatozoon, Sarcocystis, Cryptosporidium, Neospora, Toxoplasma
- diagnostic stage for final host can be small
- asexual stage causes damage
- cyst stage (oocyst)
- oocyst: ‘the diagnostic feature’
Piroplasmorida
- parasites of blood cells
- vectors: ticks
- sexual repro occurs in ticks
- asexual repro in host animal
- e.g. Babes, Theileria
Haemosporida
- parasites of blood cells
- vectors: biting insects
- sexual repro occurs in insects
- e.g. Plasmodium (malaria)
Goussia oocysts
- 4 sporocysts each with 2 sporozoites
- release of sporozoites from sporocysts is via longitudinal suture
Eimeria oocysts
- 4 sporocysts each with 2 sporozoites
- release of sporozoites from sporocysts is via Stieda body at apex of sporocyst
Epieimeria sp.
- epicellular development
Crystallospora sp.
- sporocysts with a regular crystalline appearance
Apicomplexa - one host
- many Eimeria and Goussia spp. sporulate outside of host
Apicomplexa - 2 hosts
- e.g. Sarcocystis spp.
Toxoplasma gondii
- Apicomplexa
- obligate intracellular, parasitic alveolate
- causes toxoplasmosis
cyst form
- for survival
Myxozoa
- parasitic jellyfish (Cnidaria)
- have 2 host life cycle (obligate parasites)
polar capsule/filaments
- used in sporoplasm release
- evolved/derived nematocyst
Myxozoan polar capsules are nematocyst-like structures -> shared ancestral feature. T/F?
True
Myxobolus cerebralis
- characteristic erratic tail chasing behavior (whirling disease)
- blackened caudal area due to damage of CNS
actinospore
?
myxospore
- defining diagnostic feature for myxosporea infections
histozoic
- develop inside muscle tissues (skeletal muscle) and other organs
- pathogenic
coelozoic
- develop inside coelom-like spaces
- e.g. the gallbladder
- not pathogenic
Why are we interested in the Myxozoa?
- used to help monitor host populations
- serve as biological tags
biological tags (BTs)
- living biological markers, usually parasites, that can be used to indicate changes/movements in certain systems or populations.
desirable properties of a parasite for use as a biological tag
- easily detected and identified (microscopy & PCR)
- do not cause serious damage/pathology to host
polar capsules
- used to help infect a new host
- related to the stinging cells (nematocysts) in non-parasitic cnidaria
