Download than meets the mouth - LFSC680-TIP2

Marine Organisms and
Natural Products: Why are there poisons and
how did they get there?
“More than Meets the Mouth”
Why do marine organisms produce
secondary metabolites:
Many plants and animals, both terrestrial and
marine, produce compounds that help them
survive by, for example, deterring potential
predators, warding off pathogens, keeping their
living space free from competitors, and even
reducing the impact of exposure to environmental
stresses, such as high levels of solar UV radiation.
Thus, these chemicals have an enormous impact
on the outcome of interactions between species
and the structure and function of communities
and ecosystems.
Secondary metabolites
• Many organisms have been found to
defend themselves by producing toxins or
other small molecules.
• Also known as natural products.
• Chemicals which posses an unknown
functional role.
• Generally limited to a specific species or
even a chemotypical subset of a species.
Examples of Marine Organisms that
produce or harbor natural products:
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Sponges
Algae
Bryozoans
Mollusks
Cnidarians
Tunicates
Echinoderms
Sea worms
Microorganisms
Evolution of chemical defense:
Animals that are mobile or that have hard shells
or spines are typically not defended by noxious
or toxic chemicals.
• Nudibranches, also
Sea slugs:
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called sea slugs,
typically get their
defensive chemistry
from the sponges,
bryozoans, and sea
squirts that they eat.
Nudibranches also put
defensive compounds
in their soft egg
ribbons.
Many sea slugs have
an unusual
endosymbiotic
association between
algal chloroplasts and
a marine mollusc,
resulting in
photosynthetic sea
slugs.
Sea weed:
• Soft fleshy seaweeds
found where herbivorous
fishes and invertebrates
are abundant typically
deter predators through
the production of
distasteful secondary
metabolites.
• Phenolics appear to
deter herbivores, but not
fish.
• Most algae produce both
polyphenolic and
nonpolyphenolic
secondary metabolites.
Sponges:
• An abundant group of
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coral-reef invertebrates
that are very chemically
rich.
Many sponge chemicals
effectively deter
potential predators, and
many of the distasteful
compounds, such as
formoside, have now
been isolated and
structurally
characterized.
They occasionally
develop symbiotic
(mutually beneficial)
relationship with both
algae and bacteria and
may contain many
complex chemicals that
have medicinal value.
Soft coral:
• Gorgonians, a type of soft
coral, lack the hard
calcium carbonate
skeleton.
• Their soft texture would
seem to make them
susceptible to diverse reef
predators, but the many
novel compounds they
produce effectively
protect them from
predators.
• Several chemicals have
been collected from
various types of soft
coral: sesquiterpenoids,
tetraprenylbenzenoids,
diphenylpropane,
methylenecholesterols
and diterpenoids.
Cnidarians:
• Hydroids are related
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to corals and
anemones.
Stinging organelles
called nematocysts
protect hydroids that
lack a chemical
defense.
Chemicals, like
tridentatol A, defend
some hydroids from
predators.
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Sea squirts:
• Tunicates, also called sea
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squirts, are a rich source of
secondary metabolites,
several of which have been
shown to deter feeding by
fish, crabs and snails.
As chemical defenses, many
sea squirts intake and
maintain an extremely high
concentration of vanadium in
the blood, have a very low pH
of the tunic due to acid in
easily-ruptured bladder cells,
and/or produce secondary
metabolites harmful to
predators and invaders.
Some of these metabolites are
toxic to cells and are of
potential use in
pharmaceuticals.
Isopod:
• Has a thick carpet of blue•
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green alga growing on it.
The alga produces a
noxious compound that
deters fish from eating the
isopod.
Because the isopod isn’t
eaten by fish, instead of
hiding from fish, the
isopods live on sun exposed
substrates where their
symbiont gets plenty of
light for photosynthesis.
The isopod also eats its
symbiont.
References:
• Charles D. Amsler , James B. McClintock , and Bill J. Baker Secondary
Metabolites as Mediators of Trophic Interactions Among
Antarctic Marine Organisms
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Amer. Zool. 41: 17-26.
Kenneth L. Rinehart Secondary Metabolites from Marine Organisms,
Ciba Foundation Symposium 171 - Secondary Metabolites: their
Function and Evolution, (2007) 236-254.
http://www2.csusm.edu/trischman/research/ChemicalDefense.html
Botanica Marina. Volume 51, Issue 3, Pages 161–162, ISSN (Online)
1437-4323, ISSN (Print) 0006-8055, DOI: 10.1515/BOT.2008.031, June
2008.
http://uncw.edu/aquarius/education/lessons/chemical%20ecology.html
http://en.wikipedia.org/wiki/Ascidiacea
http://www.shvoong.com/medicine-and-health/1613367-discoverydevelopment-marine-sponge-secondary/
http://www.umaine.edu/bmmb/faculty/index
Picture References:
• http://www.cartoonstock.com/newscartoons/cartoonists/cwa/lowres/cwan8
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1l.jpg
http://www.snapshots.net/cartoons/00235-daily-cartoons-chemicalweapons.gif
http://www.sciencedaily.com/articles/plants_animals/marine_biology/
http://vocation.blogsome.com/2006/10/14/kedah/
http://www.junglewalk.com/photos/invertebrate-pictures.htm
http://bioephemera.com/2007/09/03/
http://www.imagequest3d.com/pages/general/news/seasquirts/seasquirts.h
tm
http://a.abcnews.com/Technology/AmazingAnimals/popup?id=4886452&co
ntentIndex=1&page=4&start=false
http://www.photoeverywhere.co.uk/britain/ukwild/slides/seaweed0313.htm
http://www.monsterreef.com/index.php/cPath/2
http://mymarinebiologyhome.blogspot.com/2007/09/shape-of-life090807.html
http://icb.oxfordjournals.org/cgi/content/full/41/1/17