Biology 625
Fall semester lecture note outline

Updated: 24 September 1999

The text below simply represents a crude lecture outline of one of the topics covered in class. It is not meant to substitute for attending lectures or ignoring the textbook. Additional material, including line drawings, kodachromes, and more extensive information on life-cycles and basic biology, will be supplied in the lectures.

TOPIC 30. Introduction to the phylum Apicomplexa

  1. evolutionarily related to the dinoflagellates
  2. all members possess an apical complex consisting generally of some or all of the following:
    1. polar ring (1-2 electron dense structures immediately behind the anterior tip of the zoite and directly under the plasma membrane)
    2. micronemes (convoluted, elongate bodies in anterior end of zoites whose contents are released during host cell penetration and may be involved in affecting plasma membrane fluidity)
    3. rhoptries (elongate, club-shaped organelles in anterior portion of zoite whose contents are released during host cell penetration and may be involved in forming the membranous scaffolding supporting the zoite within the parasitophorous vacuole)
    4. subpellicular microtubules (microtubules under the plasma membrane that run posteriorly and parallel to the axis of the zoite)
    5. conoid (truncated, hollow cone of spirally arranged fibers within the polar rings)
  3. micropores usually present at some stage which are morphologically similar to clathrin-coated pits and are involved in endocytosis
  4. sexual reproduction by syngamy
  5. all parasitic; no free-living members
  6. life-cycle generally involves merogony (asexual reproduction), followed by gamogony (sexual reproduction) and sporogony
  7. classification (you will only need to learn representatives of some of these taxa)
    1. Class: Gregarina
      1. mature gamont large, usually extracellular
      2. mucron or epimerite present
      3. gamogony usually involving similar numbers of gametes
      4. syzygy normally present
      5. most gametes similar in appearance
      6. zygotes in gametocysts in most cases
      7. 3 orders known
        1. Order: Archigregarinorida (merogony, gamogony, and sporogony present)
        2. Order: Eugregariiorida (merogony absent; gamogony and sporogony present)
          1. Suborder: Blastogregarinorina
          2. Suborder: Aseptatinorina
          3. Suborder: Septatinorina
        3. Order: Neogregarinorida (merogony present but acquired secondarily; gamogony and sporogony present)
    2. Class: Coccidiasina
      1. gamonts normally present, usually small and intracellular
      2. mucrons and epimerites absent
      3. syzygy usually absent, but if present involves gametes
      4. most anisogamous
      5. merogony, gamogony, and sporogony normally present
      6. 4 orders
        1. Order: Agamococcidiorida (merogony and gamogony absent; sporogony present)
        2. Order: Ixorheorida (gamogony absent; merogony and sporogony present)
        3. Order: Protococcidiorida (Coelotrophiida) (merogony absent; gamogony and sporogony present; extracellular)
        4. Order: Eucoccidiorida (merogony, gamogony, and sporogony normally present)
          1. Suborder: Adeleorina
          2. Suborder: Eimeriorina
          3. Suborder: Haemosporina
          4. Suborder: Piroplasmina

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