Poisonous Plants, Fungi, and Algae

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Poisonous Plants, Fungi, and Algae

• Algal Toxins

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Algal Blooms and Harmful Algal Blooms
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Kingdom Monera

• Cyanobacteria - blue green algae
• Used as a food source Nostoc, Spirulina (since
  ancient times - today protein additive)
• Toxins produced by several species can cause
  problems during blooms

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Kingdom Protista

• Six divisions of algae
• Division Pyrrophyta - dinoflagellates
• Division Chrysophyta - diatoms
• Division Euglenophyta - euglenoids
• Division Chlorophyta - green algae
• Division Rhodophyta - red algae
• Division Phaeophyta - brown algae

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Toxic Cyanobacteria

• Normally algal cells only release the toxins when
  the cells die or when they age and become leaky
• Poisoning typically occurs when animals ingest
  whole cells
• If water is treated to break up a bloom, it is
  possible for fatal levels of the toxin to be
  released
• 12 genera of cyanobacteria known to be
  toxin-producers.
• Two of the most toxic - Anabaena and Microcystis.

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Types of toxins

• Two groups of deadly toxins in the cyanobacteria
• Neurotoxins - alkaloids - nervous systems
• Anatoxins - Very Fast Death Factor 4 min bind
  to acetylchone receptors and cause respiratory
  paralysis
• Saxitoxins neurological dysfunction and
  paralysis block sodium channels on neurons
  (also in some dinoflagellates)
• Hepatotoxins - cyclopeptides - target the liver
• Microcystins disrupt cytoskeleton in liver
  cause liver cells to collapse blood pools in
  liver causing fatalities may also be
  carcinogenic
• Other less deadly toxins swimmers itch

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Anabaena

• Anabaena - a genus of filamentous N2-fixing
  cyanobacteria
• Known for producing a suite of cyanotoxins which
  range from the neurotoxic anatoxins and
  saxitoxins to the hepatotoxic microcystins.
• Genus can be found throughout the world

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Anabaena
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Microcystis

• Microcystis spp. are single-celled, colonial,
  freshwater cyanobacteria
• World-wide distribution
• Microcystins (hepatotoxins) are main toxin type
• M. aeruginosa and M. viridis appear to be the
  most common microcystin-prodcuing species.

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Microcystis
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Dinoflagellates

• Unicellular algae covered with cellulose plates
  giving an armored appearance
• Important to the food chain in marine and fresh
  water
• Some marine species cause Red Tides
• Bloom conditions
• Color the water red
• Produce powerful toxins
• Pfiesteria newly recognized problem

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Dinoflagellates
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Dinoflagellates and Red Tides

• Several species of dinoflagellates, especially
  Gymnodinium breve, Alexandrium spp, produce
  powerful toxins that can cause massive fish kills
• As schools of fish swim through a bloom, the
  dinoflagellates may be disrupted or killed,
  releasing neurotoxins into the water
• The toxins damage the gills or suppress heart
  rate and result in asphyxiation - hundred or
  thousands of dead fish wash up on beaches

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Other Problems

• In other instances, the toxins accumulate in
  various filter feeding shellfish
• When the shellfish are eaten the toxins can
  affect humans
• Cause various syndromes depending on the
  dinoflagellate and type of toxin

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Dinoflagellate Poisonings

• Paralytic Shellfish Poisoning (PSP) saxitoxin
• Diarrhetic Shellfish Poisoning (DSP)
• Neurotoxic Shellfish Poisoning (NSP) usually
  only fish kills
• Ciguatera Fish Poisoning (CFP) GI,
  neurological, and cardiovascular symptoms from
  eating contaminated fish (fish not affected)
• Pfiesteria piscicida recently identified problem

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Pfiesteria piscicida

• Pfiesteria piscicida implicated as the organism
  responsible for recent fish kills and fish
  disease
• Since the early 1990s toxins produced by
  Pfiesteria may have killed over one billion fish
  in North Carolina alone with other outbreaks
  along east coast
• Toxins not identified yet
• People exposed to toxins have developed skin and
  neurological problems

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Pfiesteria

• Complex life cycle
• Appears to be around 24 different stages in the
  life cycle with flagellated, amoeboid, and
  encysted stages
• Only 3 stages appear to form toxins