Protozoan 20Groups by 15X86732


									Protozoan Groups
September 11, 2004
Quickie History
• First life on earth approximately 3.5 million years ago.
• The first cells were prokaryotic, bacteria-like organisms.
• Eventually produced eukaryotic cells through endosymbiosis.
• Endosymbiosis is a symbiosis in which the symbiont lives in a host. It is thought that one
   prokaryote came to live in another and the internal symbiont eventually became organelles
   such as mitochondria.
• Mitochondria are the cells' power sources. They are distinct organelles with two membranes.
   Usually they are rod-shaped, however they can be round. The outer membrane limits the
   organelle. The inner membrane is thrown into folds or shelves that project inward.

What is a protozoan?
• A protozoan is a complete organisms in which all activities are carried on within the limits of a
  single plasma membrane.
• There are over 64,000 species that have been named – over half of these from fossils.
• They are complex because their various organelles tend to be more specialized than those of
  an average cell in a multicellular organism.
• Particular organelles may perform as skeletons, sensory structures, conducting mechanisms
  and feeding structures.

Where might you encounter one?
•   Protozoa are found where life exists. They are highly adaptable and easily distributed from
    place to place.
•   They require moisture.
•   They may be free swimming or sessile
• Some species may have spanned geological eras of more than 100 million years.
How are they associated with the animal kingdom?
• All unicellular organisms used to be lumped together under kingdom Protista.
• Recent studies have suggested that combining all unicellular eukaryotes with the unicellular
  algae into one kingdom was sloppy.
• Some are animal-like
• Some are free living, some commensalistic and some parasitic.
Why are they here…what do they contribute?
• Biological contributions:
   – Intracellular specialization
   – Division of labor between cells
   – Asexual reproduction
   – True sexual reproduction
   – Simplest reflexes and instincts represented
   – Exoskeletons
   – All types of nutrition
   – Basic enzyme systems
   – Well developed forms of aquatic locomotion
Characteristics of protozoan phyla
• Unicellular – but some with multicellular stages in their life cycle.
• Mostly microscopic
• All symmetries represented
• No germ layer present
• No organs or tissues but specialized organelles
• Locomotion by falsefeet, flagella and cilia
• Some with endo or exoskeleton but most naked
• All types of nutrition
• Land or water habitats
• Asexual or sexual reproduction
How do they get around?
•   Locomotor organelles
     – Protozoans employ cilia, psuedopodia or flagella for locomotion

• Lobopodia
     – Rather large, blunt extensions of the cell body containing both central, granular endoplasm
       and ectoplasm
• Filipodia are thin extensions, usually branching and containing only ectoplasm
• Axon = axis
• Podon = small foot
• These are long, slender, somewhat permanent pseudopodium found in certain sarcodine

•   Noun
•   1. Protozoa that move and capture food by forming pseudopods.

• A microscopic hair like process extending from the surface of a cell or unicellular organism.
    Capable of rhythmical motion, it acts in unison with other such structures to bring about the
    movement of the cell or of the surrounding medium.
What and how do they eat?
•   Autotrophs – make their own food
•   Hetertrophs – must have organic molecules synthesized by other organisms.
•   Ingest visible forms (phagotrophs) of foods and soluble forms (osmotrophs).
• Phagocytosis: surrounding food particle.
What then?
•   Osmoregulation – function of one or more of the contractile vacuoles. Usually located in the
    ectoplasm, they act as a pump to remove excess water from the cytoplasm.
• Some have cytopyge which is a chracteristic structure for excretion of wastes.
How do they reproduce?
• Asexually
   – Fission – division of body into two or more parts
     – Budding – outgrowth of the parent that separates and is smaller than the parent – then
       grows to adult size.
     – Multiple fission or schizogony – numerous individuals produced simultaneously
     – Sporogony – when multiple fission leads to spore formation.
• Gametic meiosis – not yet
• Zygotic meiosis – not yet
• Intermediary meiosis – not yet
• Syngamy - The fusion of two gametes in fertilization.
• Autogamy – self fertilization
• Conjugation - A process of sexual reproduction in which ciliate protozoans of the same
  species temporarily couple and exchange genetic material
Phylum Retortamonada
•   Retorqueo = to twist back
•   Monas = single unit
•   Mitochondria and golgi bodies lacking
•   Three anterior and one recurrent (running toward posterior) flagellum lying in a groove
• Intestinal parasite
What is a Golgi Body?
• n : a net-like structure in the cytoplasm of animal cells (especially in those cells that produce

Class Diplomonadea
• Diploos = double
• Monas = unit
• One or two groups of kinetosomes with a nucleaus
• Individual mastigonts with one to four flagella
• Mitotic spindle within nucleus
• Cysts present
• Free living or parasitic
What is a mastigont?
•   Also called kinetid
• The kinetid (or mastigont) consists of the basal bodies and all of their appendages (striated
    fibres and microtubule bundles).
• In ciliates the mastigonts typically consist of:
• a pair of basal bodies positioned one anterior to the other,
• a striated fibre (called the kinetodesmal fibre that is attached to the posterior basal body, and
    which extends anteriorly and the the cells right.
• a transverse microtubule bundle that extends from the posterior basal body to the cell's left a
  posterior microtubule bundle that extends posterior and upward to the cell's right from the
  posterior basal body.
Order Diplomonadida
•   Two karyomastigonts each with four flagella, one recurrent; with variety of microtubular bands
•   Example: Giardia.

Phylum Axostylata
•   Axon = axle
•   Stylos = stake
•   With an axostyle made of microtubules

Class Parabasalea
•   Para = beside
•   Basis = base
•   Refers to parabasal body = Golgi
•   With very large Golgi bodies associated with karyomastigont
• Up to thousands of flagella
Order Trichomonadida
• Trichos = hair
• Monas = unit
• Typically at least some kinetosomes associated with rootlet filaments
• Parabasal body present
• Division spindle extranuclear
• Hydrogenosomes present
• No sexual reproduction
• True cysts rare
• All parasitic
• Example: Trichomonas

Phylum Euglenozoa
•   Eu = true
•   Glene = cavity or socket
•   Zoon = animal
•   With cortical microtubules
•   Flagella often with paraxial rod
•   Mitochondria with discoid cristae
• Mucleoli persist during mitosis
Subphylum Euglenida
•  With pellicular microtubules that stiffen pellicle
Class Euglenoidea
•   Two heterokont flagella (flagella with different structures) arising from apical reservoir
•   Some species with light-sensitive stigma and chloroplasts
•   Example: Euglena

Subphylum Kinetoplasta
•   Kinetos = to move
•   Plastos = molded or formed
•   With a unique mitochondrion containing a large disc of DNA
•  Paraxial rod
Class Trypanosomatidea
•   Trypanon = a borer
•   Soma = the body
•   One or two flagella arising from pocket
•   Flagella typically with paraxial rod that parallels axoneme
•   All parasitic

Phylum Apicomplexa
• Apex = tip
• Complex = twisted around
• Characteristic set of organelles associated with anterior end present in some development
• Cilia and flagella absent except for flagellated microgametes in some groups
• Cysts often present
• All parasitic
Class Gregarinea
• Gregarius = belonging to a herd or flock
• Mature gamonts (individuals that produce gametes)
• Large extracellular oocysts within gametocysts
• Parasites of digestive tract of invertebrates
• Life cycle usually with one host
• Examples: monocystis and gregarina
• Monocystis                                          Life                                    Cycle
   A.     Feeding      Trophozoite      with     host     sperm    tails    on     outer     surface
   B.                           Mating                          gamont                           pair
   C.           Gamonts             producing          gametes           within          gametocyst
   D.         Pairing        of        mating         gametes         to        form        zygotes
   E.                 Haploid                oocysts               within                gametocyst
   F.            Single            oocyst           with          developing             sporozoites
   G.             Mature              oocyst             with           eight            sporozoites
   H. Oocyst shedding sporozoites
Class Coccidea
• Kokkos = kernal or grain
• Mature gamonts are small and typically inracellular
• Life cycle tpically with merogony, gametogony and sporogony
• Most species in vertbrates
• Examples: cryptosporidium
• Cyclospora
• Etimeria
• Toxoplasma
• Plasmodium
• Babesia
What is merogony?
• Merogony: development of an embryo by a process that is genetically equivalent to male
  parthenogenesis and that involves segmentation and differentiation of an egg or egg fragment
  deprived of its own nucleus but having a functional male nucleus introduced
•   gametogenesis
•   n : the development and maturation of sex cells through meiosis
• Gametogony = gamogenesis especially of protozoans
and sporogony?
•   Reproduction by multiple fission of a spore or zygote, characteristic of many sporozoans.
    Sporogony results in the production of sporozoites.

Plasmodium (Malaria)
• Note, two parasites in one bovine red blood cell.
• The vector for Babesia is typically a tick.
• In cattle this parasite causes disease known as Texas Cattle Fever or red-water fever.
• The disease can kill cattle within a weak.
Class Ciliophora
• Cillium – eyelash
• Phora – bearing
• Cillia or cilliary organelles in at least one stage of life cycle
• Two types of nuclei
• Binary fission across rows of cilia
• Budding and multiple fission
• Sexuality involving conjugation and autogamy
• Nutrition hetertrophic
• Has contractile vacuole
• Most species free living, many commensal, some parasitic
• Examples: Paramecium
• Vorticella
• Stentor
• paramecium is a ciliated single celled creature.
• The various species of paramecium can be distinguished from other ciliates by their cigar or
   slipper shape and the undulating membrane within the peristome - a furrow that leads to the
   cytostome, where food vacuoles are formed.
• Most paramecia are quite large for protozoa, approx. 0.5 mm long
•  It is a very interesting, stalked ciliate with an inverted bell shape. The stalk contains a
   contractile fibril called a myoneme. When stimulated, it shortens, causing the stalk to
   coil like a spring.
•  Vorticella usually anchor themselves to small particles of material however, it is not
   uncommon to see them free swimming. When they undergo fission, they split along the
   longitudinal axis in a process called budding. When they finally split apart, one keeps
   the myoneme and the other free swims away and grows its own. The main purpose for
   the cilia at the top is to sweep food down into the gullet.

• Stentor is a very large ciliate measuring from 500-2000 microns long when extended.
• Stentor coeruleus is a very large trumpet shaped, blue to blue-green ciliate with a
   macronucleus that looks like a string of beads (dark connected dots on the left). With
   many myonemes, it can contract into a ball. It may also swim freely both extended or
Phylum Dinoflagellata
• Dinos = whirling
• Flagellum = little whip
• Typically with two flagella, one transverse and one trailing
• Body usually grooved transversely and longitudinally
• Chromoplasts usually yellow or dark brown, occasionally green or blue-green bearing
  chlorophylls a and c
• Nucleus unique among eukaryotes in having chromosomes that lack or have low levels of
• Mitosis intranuclear
• Body form sometimes of spherical unicells, colonies or simple filaments
• Sexual reproduction present
• Members free living, and planktonic, parasitic or mutualistic
• Examples: zooxanthella, ceratium, noctiluca
• Zooxanthellae are best known for their role in the life of reef-forming corals. In tropical waters
  almost all coral animals contain a colony of zooxanthellae. Without these symbiotic plants, the
  coral animals would be unable to obtain enough nutrients to build their calcium carbonate
  skeletons, which accumulate to form the vast coral reefs of the tropics.

• Noctiluca scintillans, commonly known as the seasparkle.
• a dinoflagellate, a little single-celled algae. Floating in swarms of millions these organisms
  cause the glowing of the sea.
• The archetype of a dinoflagellate has a flattened spherical body shape and is armoured by
  plates covered with an intricate texture. They propel themselves with two (or sometimes more)
  flagella. One is pointed downward, the other is running as a spiral through a groove running
  along the equator of the cell. Noctiluca however has a different body plan. It forms a gas bag
  that enables the creature to float right under the surface of the ocean. There still are two
  flagella although one is exceptionally thick.
• elegant shape, which makes it easy to identify. The cell 'body' has 'arms' more or less
  developed in accordance with each sub-species. They are used as floats but they surely
  create a great resistance to motion in water and this species doesn't move too quickly.

• Informal grouping
• Move by pseudopodia or locomotive protoplasmic flow without discrete pseudopodia
• Flagella usually restricted to development or other temporary stages
• Body naked or with external or internal test or skeleton
• Asexual reproduction by fission
• If sexuality present, usually associated with flagellated gametes
• Most free living
•   Locomotion by lobopodia, filopodia or by protoplasmic flow without production of discrete
•   Examples:
     – Amoeba
     – Endoamoeba
     – Arcella
     – Chlamydophrys

• The Arcella is a small amoeba that lives in a light brown or transparent chitinous "test"
• It is dome like on the top and concave on the bottom. They are from 50-200 um wide.
• Pseudopods extend out from the shell and are used for locomotion.

•   Locomotion by reticulopodia
•   Includes foraminiferans
•   Examples: globigerina
•  vertebralima
•   Locomotion by axopodia
•   Includes radiolarians
•   Examples:
•   actinophrys
•   Clathrulina

Phylum Chlorophyta
•   Chloros = green
•   Phyton = plant
•   Unicellular and multicellular algae
•   Contains photosynthetic pigments of chlorophyll a and b
•   Mostly free-living photoautotrophs
•   Reserve food is starch

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