Biology 625
Fall semester lecture note outline

Updated: 03 October 2003

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 29. Amoebae

  1. Organisms with pseudopodia or movement with protoplasmic flow without distinct pseudopodia
  2. flagella occasionally present in some forms, but usually restricted to temporary, developmental, or dispersal stages
  3. body either naked, or with internal or external skeleton/test
  4. asexual reproduction by fission
  5. sexual reproduction occasionally present, usually associated with flagellated gametes but occsionally amoeboid gametes
  6. most amoebae free-living and marine; few parasitic
  7. 3 distinct groups now recognized, sometimes categorized at either the subphylum or superclass level
    1. Amoebozoa (or Rhizopoda)
      1. move by lobopodia, filopodia, reticulopodia, or by protoplasmic flow without distinct pseudopodia
      2. The class Lobosea contains the only parasitic members to be discussed in class
        1. pseudopodia lobose or filariform and produced by distinct hyaline lobe; uninucleate
        2. 2 groups of importance here
          1. Order: Amoebida (no flagellate stages) (i.e. Acanthamoeba, Endamoeba, Endolimax, Entamoeba, Hartmannella, Hydramoeba, Iodamoeba, Paramoeba)
          2. Order: Schizopyrenida (body monopodal cylinder, usually moving by eruptive, hyaline bulges; most with temporary flagellate stages) (i.e. Balamuthia, Naegleria, Vahlkampfia)
    2. Granuloreticulosa (you will not be tested over this taxon)
    3. Actinopoda (you will not be tested over this taxon)

Representative intestinal amoebae

  1. Endamoeba spp.
    1. inner nuclear ring of endosomal granules
    2. cysts produced
    3. typically in invertebrates
    4. typical species
      1. Endamoeba blattae (colon of cockroaches)
      2. Endamoeba simulans (gut of termites)
  2. Entamoeba spp.
    1. distinct endosome; peripheral chromatin at nuclear membrane
    2. cysts usually produced
    3. some species parasitized by parasitic fungus Sphaerita sp.
    4. 4 distinct groups or complexes recognized
      1. Entamoeba histolytica group
        1. small, centrally located endosome
        2. ring of peripheral granules at inner surface of nuclear membrane
        3. cysts with 4 nuclei
        4. chromatoidal bars often blunt ended
        5. most pathogens seem to be in this group, and these species can ulcerate the gut wall and abcess nonintestinal sites
        6. representative species
          1. Entamoeba anatis (intestine of ducks)
          2. Entamoeba dispar (intestine of primates; nonpathogenic)
          3. Entamoeba equi (intestine of horses)
          4. Entamoeba hartmanni (intestine of primates; non pathogenic)
          5. Entamoeba histolytica (intestine of primates, canids, swine; potentially pathogenic)
          6. Entamoeba invadens (intestine of reptiles; nonpathogenic in turtles; pathogenic in snakes)
          7. Entamoeba moshkovskii (intestine of primates; nonpathogenic)
        7. President Thomas Jefferson died of dysentery in 1826. Some historians have stated that the symptoms were identical to amoebic dysentery
        8. President William Taft, then Governor of the Philippines, developed an ulceration of the perineum in 1901 and nearly died when it ruptured. In 1903, he was diagnosed with amoebic dysentery leading some to conclude that the original ulcer was due to the parasite
        9. Actress Kate Winslet (unforgettable "Rose") missed the premier opening of her film "Titanic" in London in 1997 because she acquired amoebic dysentery while filming in Morocco.
        10. Actress and AIDS activist Elizabeth Taylor is reputed to have acquired amoebic dysentery in 1975 while filming "The Blue Bird" in Russia
        11. Actor Jason Robards acquired amoebic dysentery in Peru in 1979 and was forced to quit during filming of "Burden of Dreams."
        12. Actress Carol Landis developed amoebic dysentery in 1945 while touring with the USO
        13. Novelist Ernest Hemingway suffered from amoebic dysentery between 1932 and 1933, shortly after returning from Africa
        14. Actor Kirk Douglas is reputed to have come down with amoebic dysentery while in the Navy during WWII
        15. Both Henry Morton Stanley and Dr. David Livingstone suffered from amoebic dysentery during their explorations of Africa
        16. Actress Lois Maxwell ("MoneyPenny") suffered from amoebic dysentery in England after returning from Italy during WWII
        17. Director John Ford apparently suffered from amoebic dysentery during filming of "Mogambo" in Africa in 1952
        18. Jock Mahoney, actor, is reputed to have acquired amoebic dysentery, dengue, and pneumonia while filming "Tarzan's Three Challenges" in 1963. The actor lost 45 lbs during filming.
        19. Montgomery Clift apparently contracted amoebic dysentery in Mexico in 1939
        20. Chief Justince Harlan F. Stone developed amoebic dysentery in the mid 1940's, according to his daughters writings in the 1978 Supreme Court Historical Society Yearbook
        21. A family biography of Spanish-American war Brigadier General Harry L. Haskell states that he died in 1908 of amoebic dysentery and malaria he contracted while stationed in Cuba
        22. When he was 10 years old, Will Roger's mother (Mary) died of amoebic dysentery
        23. According to the New York Times, actor/director George C. Scott had bouts of amoebic dysentery while filming "The Savage is Loose" in 1974
      2. Entamoeba coli group
        1. eccentric endosome
        2. ring of coarse peripheral granules at inner surface of nuclear membrane
        3. cysts with 8-more nuclei
        4. chromatoidal bars often splintered
        5. may cause diarrhea, but most species noninvasive
        6. representative species
          1. Entamoeba caviae (intestine of guinea pigs)
          2. Entamoeba coli (intestine of primates, canids, swine)
          3. Entamoeba cuniculi (intestine of rabbits)
          4. Entamoeba muris (intestine of rodents)
          5. Entamoeba wenyoni (intestine of goats)
      3. Entamoeba bovis group
        1. endosome varies in size
        2. peripheral granules variable
        3. cysts with 1-2 nuclei
        4. chromotoidal bars either rounded or splintered
        5. some species cause diarrhea; however, most noninvasive
        6. representative species
          1. Entamoeba bovis (intestine of bovids)
          2. Entamoeba chattoni (=E. poelecki; =E. suis) (intestine of primates and swine)
          3. Entamoeba dilimani (intestine of goats)
          4. Entamoeba ovis (intestine of sheep, goats)
          5. Entamoeba struthionis (intestine of ostriches and rhea)
      4. Entamoeba gingivalis group
        1. small, central endosome
        2. small peripheral chromatin granules
        3. no cysts produced
        4. all species oral
        5. representative species
          1. Entamoeba equibuccalis (horses)
          2. Entamoeba gingivalis (primates, canids, felids)
          3. Entamoeba suigingivalis (swine)
  3. Endolimax spp.
    1. live in colon of vertebrates and invertebrates
    2. typically small amoebae, producing small cysts with 4 nuclei
    3. large endosomes in trophozoite
    4. cysts often with small, claw-shaped chromatoidal bars
    5. representative species
      1. Endolimax clevelandi (intestine of emydid turtles)
      2. Endolimax nana (intestine of primates)
  4. Hydramoeba hydroxena
    1. obligatory ectoparasite and endoparasite of hydras and freshwater medusae
    2. reported in several countries worldwide; may be cosmopolitan
    3. trophozoites 20-200 micrometers; cysts 25-30 micrometers in diameter with single nucleus and vacuole
    4. kills cnidarians in 6-10 days
  5. Iodamoeba buetschlii
    1. in primates and swine
    2. nucelus with large nucleus and large endosome
    3. trophozoites 6-25 micrometers
    4. cysts uninucleate and subspherical, with large glycogen globule
  6. Paramoeba perniciosa
    1. in crabs, Callinectes sapidus, on East US coast; results in gray crab disease (gray discoloration of ventral surface) with resulting mortality due to destruction of ventral carapace
    2. also reported from Cancer irroratus and Homarus americanus
    3. trophozoites 5-15 micrometers
    4. invasive amoebae enter connectives along midgut, as well as several other areas. Advanced infections can be systematic and fatal.
    5. parasites with 2 nuceli; 1 nucleus is of parasite origin whereas other is derived from endosymbiotic prokaryote
  7. Vahlkampfia patuxent
    1. alimentary tract of oysters
    2. trophozoites up to 140 micrometers in diameter, with broad fan-like pseudopodia
    3. may be a non-pathogen

Some representative free-living species capable of causing central nervous system disease

  1. A variety of free-living soil/freshwater amoeba capable of rarely entering vertebrate through nasal passages. Trophozoites become established in the sinuses, migrate through cribiform plate and up olfactory nerves, and erode brain
  2. Species are capable of forming cysts in environment, although only some form cysts in tissues
  3. representative species
    1. Acanthamoeba spp. (5-6 spp.)
    2. Balamuthia mandrillaris
    3. Naegleria fowleri

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