PARA Lecture 4- 09/02/26

Amoebozoa

unicellular eukaryotes- most form blunt pseudopods

Pseudopod

temporary projections of the cell's cytoplasm used for movement and capturing food

What group are Apicomplexans part of

Alveolata

Main characteristics of Apicomplexans

Use an apical complex to recognize, attach to, and penetrate host cells. Most have an apicoplast.

What is the apical complex composed of

• Conoids

• Polar rings at bottom of conoids

• Rhoptries and micronemes

• Apicoplast

Conoids

spiral of microtubules at tip of apicomplexans

Rhoptries and micronemes

secretory structures that aid in invasion in apicomplexans

Apicoplast

green non-photosynthetic organelles likely acquired via secondary endosymbiosis

Rhodophytes

Photosynthetic red algae that are mostly marine and multi-cellular

How many of the rhodophytes are parasitic

8% of the 66 genera

What makes rhodophyte parasitism distinct

form fusions among adjacent cells called pit connections through which organelles of parasite gain access to host cytoplasm and begin dividing

What are hosts of parasitic rhodophytes

other species of red algae

Embryophyta

Parasitic flowering plants that possess invasive roots called haustoria

Are Embryophyta facultative or obligatory parasites

They can be either

What is another way to classify Embryophyta

Hemiparasites or Haloparasites

Hemiparasite

capable of photosynthesis- thus facultative

Haloparasite

incapable of photosynthesis and obtain all energy from their host- thus obligatory

Nucletmycea

Parasitic fungi- heterotrophs that absorb their nutrients using hyphae that can form mycelium

Heterotroph

organism that cannot produce its own food and must ingest or absorb their food (i.e. can’t photosynthesize)

Hyphae

branching filaments on parasitic fungi

Mycelium

dense networks of hyphae

What are the suggested ancestors of all fungi

parasites of algae

Parasitic animal nutritional intake methods

Most acquire nutrition via ingestion, but many parasites obtain it via absorption

What can parasitic animals also be called

Holozoa or Multicellular heterotrophs

What does natural selection act upon

intraspecific genetic variation

How do studies identify intraspecific genetic variation

Studies rely on use of microsatellite markers or single nucleotide polymorphisms

Isolate

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

Strain

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

Subspecies

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

Trypanosoma brucei example of diversity within species

Three different subspecies contain variants that allow them to have distinct host ranges, diseases caused, and geographical distributions

Why is intraspecific variation important in the context of parasite control

intraspecific variation can affect control efforts

Nematode trichostrongylus colubriformis control efforts example

in Nematode trichostrongylus colubriformis surface carbohydrates are the target for the vaccine but antigenic variation occurs within species

Hybridization

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

Troublesome traits from hybridization

Hybrids tend to express

• Greater fecundity

• Increased pathogenicity

• Infect broader spectra of hosts

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?

different strains or populations can have differences in their virulence, host range, transmission, diagnosis, and response to treatment that can affect diagnoses, effective treatments, predictions of disease severity, and etc.

Amoebozoa examples

Entamoeba spp.- more specifically entamoeba histolyctica causes amoebic dysentery

Apicomplexans example

Plasmodium falciparum- malaria parasites

Embryophyta examples

Dodder (Cuscuta)- hemiparasite that envelopes acacia tree

Nucletmycea parasite examples

Puccinia triticina (wheat leaf rust) infects wheat and other related food grain plants

Examples of holozoa

mites, lice, fleas, flukes, hookworms, tapeworms, etc.