parasitology lecture 4: parasite diversity continued

what is metamonda?

- eukaryotic parasite

- large group of flagellated, miscroscopic eukaryotes

- lack mitochondria (there is evidence that they used to have mitochondria, but they dont anymore)

- they have mitosomes in place of mitochondria

- they are anaerobic (mostly aerotolerant anaerobes)

- most live in the gut of their host (some beneficial, others parasitic)

what is an example of a metamonda?

giardia lamblia

trichomonas vaginalis

what are discoba?

- eukaryotic parasite

- united by sequence similarity of multiple genes but lacks many morphological similarities

what is an example of a discoba?

naegleria fowleri (the brain-eating ameoba)

what are the three stages of naegleria fowleri?

cyst, trophozite, and flagellate

How does Naegleria fowleri infect humans?

aquatic- swimmers snuff it deep into nasal chambers-> move through small passaged in cribriform plate and get into brain-> phagocytose brain cells-> primary amebic meningoencephalitis

what is the condition caused by naegleria fowleri?

primary amebic meningoencephalitis

what are kinetoplastids?

- classified under discoba

- possess a single mitochondria that contain a kinetoplast ((mass of linked, circular, mitochondrial DNA-> characteristic of these kinetoplastids)

what are examples of parasitic kinetoplastids?

trypanosoma, leishmania, phytomonas

what are amoebozoa?

- eukaryotic parasites

- unicellular eukaryotes

most form blunt pseudopods (for motility and food)

- within this group are many parasites such as entamoeba spp.

what is an example of an amoebozoa?

entamoeba histolytica

what does entamoeba histolytica cause?

amoebic dysentery (bloody diarrhea)

what are apicomplexans?

the largest and arguably most important phylum of parasites

- eukaryotic parasites

- besides a few symbionts of corals, this phylum is exclusively intracellular parasites

- make use of an apical complex to recognize, attach to, and penetrate host cells

- most have an apicoplast (from endosymbiosis)-> these structures help them with motility and attach to host cells

what are examples of apicomplexans?

plasmodium, toxoplasma gondii, cryptosporidium

how many groups of apicomplexans have traditional taxonomic schemes recognized?

4 groups

what are rhodophytes?

red algae

- they are distinct in their mode of parasitism

- they form fusions among adjacent cells (pit connections)

- the organelles of the parasite gain access to host cytoplasm and begin dividing

- the hosts happen to be other species of red algae

what are embryophyta?

these are parasitic plants and are classified by their ability to photosynthesize

what is a hemiparasite?

a parasite capable of photosynthesis

what is a haloparasite?

a parasite incapable of photosynthesis (they obtain all of their energy via haustoria, or invasive roots)

what are some examples of embryophyta?

1. a species of dodder (cuscute) enveloping an acacia tree-> can be hemiparasitic or haloparasitic

2. a flower of the parasitic plant Rafflesia arnoldsi-> the flower smells like rotting flesh and thereby attracts flies that serve as pollinators. this plant lacks leaves, stems, and roots. it produces an invasive haustorium that colonizes vines of other plants.

what are parasitic fungi?

- they can be unicellular or multicellular (small or large)

- they are heterotrophs and absorb their nutrients (using branching filaments of hyphae which can form sense networks called mycelium)

- suggested that ancestors of fungi were parasites of algae

what is an example of a fungal parasite?

lesion (canker) on a chesnut tree afflicted by chestnut blight

what are parasitic animals?

multicellular heterotrophs

- most require nutrition via ingestion, but many parasites obtain it via absorption

what are examples of parasitic animals?

mites, lice, fleas, flukes, hookworms, tapeworms

why is diversity within a parasite species important?

no species contains genetically uniform individuals

- intraspecific genetic variation is what natural selection acts upon

- studies rely on the use of microsatellite markers or SNP's

- think drug resistance also

what is an isolate?

a sample of a parasite species derived from a particular host at a particular time

what is a strain?

an intraspecific group of parasites that differs from other such groups in one or more treaits

what is a subspecies?

a distinct group of organisms within a species that may occupy a particular region and that can interbreed with other subspecies

what is an example of a parasite with high diversity within its own species? what illness does it cause?

trypanosoma brucei; african sleeping sickness

how can intraspecific variation affect control efforts?

think of the surface carbohydrate target for vaccine. Must keep in mind

the antigenic variation that occurs within the species!

what is hybridization?

when two species, generally considered to be related but distinct, engage in genetic exchange and viable mixed progeny result

why are hybrids important?

they generally result in troublesome traits:

- greater fecundity

- increased pathogenicity

- infect broader spectra of hosts

* not an actual card, but make sure you are able to list at least one example organism under every eukaryotic parasitic class ( see slide 14 on lecture 3)

Parasites not only differ from each other but also have intraspecific variation. From a clinical perspective, why is it important to discover and understand these variations?

- drug resistance/treatment

- vaccines/ control efforts