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Title: Dinoflagellates


1
Dinoflagellates
2
Introduction
  • Dinoflagellates are unicellular, flagellated
    protists
  • The first modern dinoflagellate was described by
    Baker in 1753
  • The dinoflagellates were first defined by Otto
    Bütschli in 1885 as the flagellate order
    Dinoflagellida. Botanists treated them as a
    division of algae, named Pyrrhophyta after the
    bioluminescent forms. They have also been called
    the Dinophyta or Dinoflagellata
  • Over 2000 species
  • Traditionally classified as algae
  • Most are microscopic, but a few reach a diameter
    of up to 2mm

3
Evolution
  • Dinoflagellates are considered to be among the
    most primitive of the eukaryotic group, the
    fossil record of the group may extend into the
    Precambrian period
  • Dinoflagellates are thought to have evolved from
    an early eukaryotic ancestral stock following the
    evolution of repeated DNA
  • Combine primitive characteristics of prokaryotes
    and advanced eukaryotic features

4
Structure
  • All dinoflagellates are surrounded by a complex
    covering called the amphiesma
  • In most dinoflagellates, this covering consists
    of cellulose plates referred to as armor
  • Others are naked

Gonyaulax polyedra
Karina brevis
5
Structure
  • Dinoflagellates have two dissimilar flagella
  • The transverse flagellum lies in a groove called
    the cingulum and provides forward motion and spin
  • The longitudinal flagellum lies in a groove
    called the sulcus and trails behind providing
    some propulsive force, but acting mainly as a
    rudder

Cingulum
Sulcus
6
Structure
  • There are three basic cell extensions
  • Lists
  • Horns
  • Spines

7
Cell Biology
  • The cytoplasm of dinoflagellates contains typical
    eukaryotic organelles
  • Dinoflagellates may also contain one or several
    distinctive organelles
  • pusule
  • eyespot
  • ocellus
  • chloroplasts

8
Cell Biology
  • The dinoflagellate nucleus is unusual
  • Most dinoflagellates are distinguished by a
    dinokaryon, a special eukaryotic nucleus
    containing fibrillar chromosomes that remain
    condensed during the cell cycle and a unique
    external mitotic spindle.
  • In most dinoflagellates, the nucleus is
    dinokaryotic throughout the entire life cycle.

N
Peridinium spp.
9
Cell Biology
  • Chloroplasts
  • bound by three membranes and contain chlorophylls
    a and c and fucoxanthin, as well as other
    accessory pigments
  • a few have chloroplasts with different
    pigmentation and structure, some with a nucleus
  • dinoflagellate chloroplasts may be remnants of
    diatoms ingested by a heterotrophic flagellate,
    which may have been the ancestor of modern
    dinoflagellates.

Ceratium furca
10
Life Cycle
  • Most dinoflagellates are haploid and reproduce
    primarily by asexual cell division (mitosis)
  • sexual reproduction also occurs through fusion of
    two individuals to form a zygote
  • may remain mobile in typical dinoflagellate form
  • may form a resting cyst, which later undergoes
    meiosis to produce new haploid cells

11
Pfiesteria piscicida life cycle
12
Ecology
  • In addition to living in the open ocean,
    dinoflagellates colonize tidal pools, sediments,
    sea-ice environments and freshwater ecosystems
  • The distribution of dinocysts may follow patterns
    based on latitude, temperature, salinity, water
    depth and ocean circulation systems.

Phytoplankton bloom in near Svalbard in Barents
Sea, Aug 13, 2002
13
Ecology
  • Many dinoflagellates are heterotrophs and have
    evolved various mechanisms to ingest prey
  • Some are autotrophs
  • Many species are capable of both heterotrophy and
    photosynthesis (mixotrophic)

mixotrophic dinoflagellate Ceratium furca
14
Ecology
  • Some dinoflagellates are predators and feed on
    bacteria, phytoplankton and smaller
    dinoflagellates
  • Some target larger prey, such as copepods,
    crustaceans and fish

Ingestion of cryptophytes by G. galatheanum,
brightfield (movie)
15
Ecology
  • Some dinoflagellate species, called
    zooxanthellae, are endosymbionts of marine
    animals and protozoa
  • lack characteristic armor and flagella, appear as
    spherical,golden-brown globules in their host
    cells

Symbiodinium microadriaticum
16
  • These play an important part in the biology of
    coral reefs
  • provide nutrients for coral
  • accelerate skeletal formation (calcification)
  • give coral its color
  • receive shelter in return
  • Coral bleaching occurs when reef-building corals
    lose their endosymbiotic dinoflagellates

17
Oblique Coral, Vadoo Diving Paradise, Maldives,
Feb 1997
Oblique Coral, Vadoo Diving Paradise, Maldives,
Dec 1997
Oblique Coral, Vadoo Diving Paradise, Maldives,
Mar 1999
18
Ecology
  • Dinoflagellate infections have been reported for
    a wide range of host organisms including
    sarcodines, ciliates, free living
    dinoflagellates, various invertebrates, and a few
    vertebrates.
  • Some dinoflagellates parasitize other parasitic
    dinoflagellates.

Blue crab cardiac tissue infected with
Hematodinium spp.
19
Ecology
  • The Dinoflagellata are sometimes called
    Pyrrhophyta (fire plants) because some species
    are capable of bioluminescence.
  • Bioluminescent dinoflagellates begin to glow as
    it gets dark, and brighten considerably when
    agitated.
  • The expression of bioluminescence is controlled
    by an internal biological rhythm.

Model of circadian rhythm
20
Noctiluca spp.
21
Significance
  • Primary Producers
  • Important primary producers in both marine
    (particularly on-shore) and freshwater
    environments

22
Significance
  • Harmful Algal Blooms
  • occur when a dinoflagellate species multiplies
    until it dominates the phytoplankton community -
    high concentrations cause the water to become
    discolored
  • often called "red tides" but can also appear
    green, yellow, or brown, depending on the type of
    dinoflagellate involved
  • considered harmful because dinoflagellates
    produce potent toxins
  • blooms can kill fish and other marine organisms,
    poison people who eat contaminated shellfish, and
    cause respiratory distress in susceptible people

23
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24
  • Types of dinoflagellate related illnesses
    (human)
  • Diarrhetic Shellfish Poisoning (DSP) considered
    by some scientists to be the most common and
    globally widespread phytoplankton related seafood
    illness.
  • Neurotoxic Shellfish Poisoning (NSP)
    gastrointestinal and neurological symptoms from
    eating shellfish that have fed on toxic Karenia
    brevis dinoflagellates
  • Paralytic Shellfish Poisoning (PSP) PSP syndrome
    is life-threatening and can result in respiratory
    arrest within 24 hours of consuming shellfish
    laced with toxins from feeding on Alexandrium
    spp.
  • Ciguatera fish poisoning (CFP) Ciguatera fish
    poisoning is caused by biotoxins produced by
    dinoflagellates that grow on seaweeds and other
    surfaces in coral reef communities.

25
  • Pfiesteria piscicida
  • normally exists in non-toxic forms, feeding on
    algae and bacteria in the water and in sediments
    of tidal rivers and estuaries
  • becomes toxic in the presence of fish,
    particularly schooling fish, triggered by their
    secretions or excrement in the water
  • Pfiesteria cells shift forms and emit a toxin
    that stuns the fish, emits other toxins that
    break down fish skin tissue, causing bleeding
    sores
  • As fish are incapacitated, the Pfiesteria cells
    feed on their tissues and blood
  • implicated as a cause of major fish kills at many
    sites along the North Carolina coast

26
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27
Nessie's Diet of Deadly Dinoflagellates
  • The Loch Ness Exploration Program has uncovered
    an exciting new theory to explain sightings of
    the famous Nessie monster.
  • Professor Arnold Stryker (33) of the
    International Marine Biology and Oceanographic
    Diversity Research Project (on secondment to the
    Loch Ness Exploration Program) has located an
    ancient organism called Pfiesteria at 8 different
    points in the loch.
  • "I did not expect to find this creature in such
    concentrations - it is a revolutionary
    discovery."
  • Pfiesteria is part of a group of pre-historic
    organisms called dinoflagellates.
  • Dr. Gunter Fishlin PhD (44) said "our Loch Ness
    Exploration Program has been looking for evidence
    of unknown creatures living in Loch Ness. We now
    believe that, while firm evidence of a large
    dinosaur living beneath the waves still eludes
    us, we have at least established the presence of
    dinoflagellates.
  • Pfesteria is a peculiar organism. It groups
    together with its fellows to form large clumps of
    slime. This slime actually displays
    "ambush-predator" qualities by attacking fish. As
    schools of fish build up in an area Pfiesteria
    starts secreting toxins which overcome them. The
    fish die from suffocation as their nervous system
    collapses and their skin tissue starts to break
    down under the impact of the toxin.
  • The interesting link for Loch Ness researches
    investigating the possibility of a large
    plesiosaur living in the depths is Pfiesteria's
    effects on humans. Dr. Fishlin explains "many
    eye-witnesses have come forward with accounts of
    their sightings of the Loch Ness monster, some of
    which include references to feelings of "lost
    time" that thy cannot explain. The toxins given
    off by Pfiesteria are hallucinogenic and research
    elsewhere has shown that a feeling of lost time
    is a common side effect.
  • Are humans around Loch Ness at risk from "the
    cells from hell"? Professor Stryker doesn't think
    so "as long as people are aware of its dangers
    and avoid parts of the loch where they see large
    clumps of algae-like slime, they should be safe.

28
  • Ciguatera poisoning
  • subtropical and tropical marine finfish
    accumulate naturally occurring dinoflagellate
    toxins through their diet
  • most common nonbacterial, fish-borne poisoning in
    the United States
  • ciguatera poisoning in humans usually involves a
    combination of gastrointestinal, neurological,
    and cardiovascular disorders

29
  • Every coastal state has reported major blooms
  • Blooms may be responsible for more than 1
    billion in losses during the last two decades

30
  • What causes HABs?
  • Marine transportation may have contributed to the
    global HAB expansion by transporting toxic
    species in ballast water
  • aquaculture activities may be related to HAB
    expansion
  • Increased nutrient loads to coastal waters may
    stimulate HAB species populations to initiate a
    bloom

A large sediment plume flowing out to sea and
associated phytoplankton bloom offshore.
Brazil, 2000.
31
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32
Sources
  • http//www.nmnh.si.edu/botany/projects/dinoflag/in
    dex.htm
  • http//www.ucmp.berkeley.edu/protista/dinoflagella
    ta.html
  • http//www.geo.ucalgary.ca/macrae/palynology/dino
    flagellates/dinoflagellates.html
  • http//en.wikipedia.org/wiki/Dinoflagellates
  • http//visibleearth.nasa.gov/
  • http//www.searay.50megs.com/hematod.html
  • http//coral.s5.com/
  • http//www.eeb.uconn.edu/Courses/EEB290/Lecture26.
    pdf
  • http//www.emedicine.com/emerg/topic100.htm
  • http//www.habhrca.noaa.gov/
  • http//www.habhrca.noaa.gov/habfacts.html
  • http//ioc.unesco.org/hab/intro.htm
  • http//www.sustainablefishery.org/index.html
  • http//geo.ucalgary.ca/macrae/Dinoflag_spindles.g
    if
  • http//www.lochness.co.uk/exhibition/dinoflagellat
    es.html
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