Protozoa

How many species in protozoa? Are they eukaryotes? What do they consist of?

65 000 species. Yes they are. Consist of a single cell but many species contain more than one nucleus during all or portions of their life cycles and certain stages such as spores may be built from more than one cell

What are most protozoans important parasites of?

The gastrointestinal tract and blood

What are two relevant genera in Euglenozoa phylum?

Trypanosoma and Leishmania

What are two species in the genera Trypanosoma? What about leishmania?

Trypanosoma: T.brucei, and T. brucei gambiense

Leishmania: L.donovani, L. tropica

What is a relevant genus for the phylum apicomplexa? What are four species in this genus?

Plasmodium. Species include: P. malariae, P.ovale, P.falciparum, P.vivax 

What are three genera in the phylum metamonada?

Chilomastix, Giardia, and Trichomonas

What is one important species in each of the three genera for the phylum metamonada?

Chilomastix mesnili, Giardia lamblia, and Trichomonas vaginalis (or muris)

What is a genus and a species in the phylum Cilliophora?

Genus: Balantidium

Species is Balantidium coli

What are three genera associated with the phylum Amoebozoa? What is an associated species with each genera?

Genus: Entamoeba, Endolimax, Iodamoeba

Species: Entamoeba coli and histolytica, Endolimax nana, Iodamoeba butschlii 

What do trypanosomes possess?

6 basic morphological forms based on shape and position of the kinetosome and kinetoplast

Describe the amastigote morphological form

It has a spheroid shape with a very short flagella projecting just above the flagellar pocket.

What is the definitive morphology for Leishmania in the vertebrate host?

Amastigote

Describe the choanomastigote morphological form 

The flagellum emerges from the collar. Kinetosomes and kinetoplasts are anterior to the nucleus. 

What genus has the choanomastigote form?

Crithidia

Describe the promastigote morphological form. What is an example of a genus that has this form?

Flagellum extends forward and the kinetsome and the kinetoplast are anterior to the nucleus. Leptomonas

Describe the opisthomastigote morphological form. What is an example of a genus that has this form?

Kinetosome and kintoplast are found between the posterior and the nucleus. Have a long flagellar pocket and no undulating membrane. Herpetomonas

Describe the epimastigote morphological form. What is an example of a genus that has this form?

Similar to promastigote as the kinetosome and kinetoplast are between the nucleus and anterior end. But they have a short undulating membrane found along the basal or proximal part of the flagellum. Blastocrithidia 

Describe the trypomastigote morphological form

Kinetoplast and kinetosome are near posterior of body. The flagella runs along the surface of the body generally continuing as a whip anterior to the body. Has an undulating membrane.

What genus has the trypomastigote as the definitive form in humans?

Trypanosoma

What is the size for trypanosoma lewisi? What morphological form is it in? Is the undulating membrane visible under 40X?

25 micrometers in length. Typical trypomastigote form. May not be

What is the definitive host for T.lewisi? Habitat? Phylum? Disease? Diagnostic feature?

Definitive host: Rat

Habitat: Blood 

Phylum: Euglenozoa

Disease: Non-pathogenic

Diagnostic feature: Perform a blood smear 

What is the size of Trypanosoma brucei gambinense? Describe morphological features. What morphological form is it in?

25-50 micrometers

Long and slender but can be broad and short if no flagellum is present or in an intermediate stage

Typical trypomastigote form in vertebrate host and epimastigote form in insect host

What is the definitive host? Habitat? Phylum? Diagnostic features of trypanosoma brucei gambiense?

Definitive host: Human

Habitat: Blood

Phylum: Euglenozoa 

Disease: Trypanosomiasis, African sleeping sickness 

Diagnostic feature: Perform a blood smear 

What morphological form is Leishmania donovani in?

Typical amastigote form in vertebrate host and promastigote form in insect host

What is the definitive host? Phylum? Habitat? Diagnostic feature of Leishmania donovani?

Definitive host: Human and dogs

Habitat: Liver and spleen

Phylum: Euglenozoa

Disease: Kala-azar, dum-dum fever, and visceral leishmaniasis

Diagnostic feature: Perform a smear 

What morphological form is leishmania tropica in?

Promastigote form when grown in culture and in insect host (gut of sandfly). Amastigote form in vertebrate host.

What is the definitive host? Phylum? Habitat? Disease? Diagnostic feature of leishmania tropica?

Definitive host: Human and dogs 

Habitat: Dermal layer of the skin 

Phylum: Euglenozoa

Disease: Dermal leishmaniasis, or Oriental sore 

Diagnostic feature: Perform a culture 

Where does the flagellum originate at for T.b.gambiense?

At the posterior of the organism but it is contained by the undulating membrane along the outside. It becomes free at the anterior part of the body.

What is the vector for African trypanosomiasis (T.b. gambiense)? What is the vector for T. lewisi?

The tsetse fly. No vector because it is non-pathogenic

What is the complete life cycle for African trypanosomiasis including diagnosis and infective stages

1. The tsetse fly takes a blood meal and injects metacyclic trypomastigotes (I)

2. Injected metacyclic trypomastigotes transform into bloodstream trypomastigotes which are carried to other sites

3. Trypomastigotes multiply by binary fission in various body fluids such as blood, lymph, and spinal fluid

4. Trypomastigotes are then in blood (D)

5. Tsetse fly will take a blood meal and blood stream trypomastigotes are ingested

6. Bloodstream trypomastigotes transform into pro cyclic trypomastigotes in tsetse flys midgut. The pro cyclic trypomastigotes multiply by binary fission

7. Procyclic trypomastigotes leave the midgut and transform into epimastigotes

8. Epimastigotes multiply in the salivary gland. They transform into metacyclic trypomastigotes and the cycle continues.

Does Leishmania donovani have a flagellum or undulating membrane? Where is the kinetoplast located?

No it does not. It is a dark rod-shaped inclusion near the round nucleus 

What do leishmania like to attack? What are they seen as here?

Macrophages and are seen as the flagellate amastigote forms.

Does leishmania tropica have an undulating membrane? What about flagellum?

No undulating membrane or flagellum but has a flagellum when in promastigote form.

What are two distinguishing characteristics that can be used to distungish between Leishmania promastigote and the trypanosoma trypomastigote?

1. Leishmania do not have an undulating membrane while trypanosoma do.

2. KS and KP are anterior to the nucleus in Leishmania while KS and KP is posterior to the nucleus in trypanosoma

How can you distinguish the nucleus from the kinetoplast in the leishmania amastigote? In what host is the amastigote form found?

The kinetoplast is rod shaped near the nucleus in the amastigote form. It is in the amastigote form in the vertebrate host and promastigote in the insect host 

What are the two genera of sand flies that transmit leishmania? New world? Old world?

New world- Lutzomyia spp

Old world- Phlebotomus spp

What is the life cycle of the sand fly that transmits leishmania? What stages are infective? Diagnostic?

1. Sandfly takes a blood meal and infects promastigote stage into the skin (I)

2. Promastigotes are phagocytozied by macrophages

3. Promastigotes transform into amastigotes inside macrophages (D)

4. Amastigotes multiply in cells (including macrophages) of various tissues until the infected cell ruptures (D)

5. The released organisms infect other cells and affect different tissues

6. A sandfly will take a blood meal and ingest an infected macrophage with amastigotes

7. Ingestion of parasitized cell

8. Amastigotes transform into promastigote stage in midgut

9. Divide in midgut and migrate to proboscis and cycle can now repeat itself

Define definitive host

It is a host where the parasite reaches sexual maturity

Define intermediate host

It is a host that is required for parasite development but one in which the parasite does not reach sexual maturity

What is schizogony/merogony?

It is where the nucleus divides multiple times before cytokinesis occurs, resulting in the simultaneous production of many daughter cells

During schizogony, what are the three possible names to call the cell?

Schizont, meront, or segmenter 

What is excystment? Encystment?

Excystment is the process of rupturing the cyst to return to an active form. While encystment is when protozoa will form a cyst (protective covering) and go into a resting state to survive harsh conditions.

What is a cytostome?

It is a specialized cell structure used for phagocytosis that protozoa have

What is ammonotelic?

It is where most of their nitrogen is secreted in ammonia and most of this diffuses directly through the cell membrane. It is a method for excretion and osmoregulation.

What is a kinetoplast?

It is a DNA containing organelle within the mitochondria and it is disc shaped 

What is a kinetosome?

It is a self-duplicating organelle that is homologous to the centriole. It is responsible for the formation of flagellum or cilia.

What is the undulating membrane?

It is a lateral expansion of the plasma membrane in flagellates that is usually associated with the flagellum

What is an axostyle?

It is a sheet of microtubules that arises from the base of the flagellum

What is gametogony?

It is the sexual phase of the life cycle in which the gametes are formed

What is sporogony?

Formation and maturation of infective stages. It gives rise to sporozoites

What is a zygote?

It is the first cell formed when a sperm fertilizes an egg

What is a vector?

It is an organism that transmits the causative agent from the reservoir to the host

What is a karyosome?

It is a knot of condensed chromosomes joined together in a limited volume of the oocyte nucleus 

What is a merozoite?

It is a small amoeboid sporozoan trophozoite produced by schizogony that is capable of initiating a new sexual or asexual cycle of development

What is a karyomastigont?

It is an organelle system in some primitive protists that consist of a nucleus, one or more basal bodies, and flagella all linked together

What is a basal body?

They are barrel-like micro tubular structures found at the base of cilia or flagellum

What is a commensal?

It is an organism that benefits and the host is neither benefitted or harmed. 

What is an isogametes? Anisogamete?

Iso- is morphologically identical to the other gamete it fuses with

Aniso- differs from the other in size or form

What is a trophozoite?

It is the active, feeding, and reproducing stage of protozoan parasites

What is syngamy?

It is the fusion of two cells or their nuclei in reproduction

What parasite is this?

Trypanosoma lewisi

What parasite is this?

Trypanosoma brucei gambiense

What parasite is this?

Leishmania tropica

What parasite is this?

Leishmania donovani