about this subject. If plants didn’t know how to defend themselves we wouldn’t have any
meadows, shrubs, forests, etc.
Smart pharmacological researchers know these facts and they prospect for plants in the wild to
produce these compounds when they are infected by viruses and bacteria, when they basically
have the flu. They test to see how good the plants are fighting off the bacteria/viruses. 90% or
more of our drugs come from the plant world.
This plant is stinging nettle and it is a weed. You get a rapid and pronounced response on your
skin that is a histamine response. Not just indigenous histamine in your cells but in the leaves of
the plant. The ‘trichomes’ or hairs are loaded by chemical cocktails i.e. histamine and
acetylcholine. They also have formic acid that helps the penetration of histamine into your skin
and the response is similar to hay fever. You take an antihistamine if you encounter this plant in
the wild. It is fascinating that plants out there are capable of producing sophisticated
neurotransmitters. It has metabolic machinery in there to make all these chemicals. If this plant
is experiencing stress i.e. feeding animals, it will produce more so the next animal that comes
along will be affected. The response is so immediate the animal will walk away and feast on
something else. People die from the histamine response when stung by an insect/bee. In the
wild a similar response would occur if deer were to eat a large amount of this herb. Intelligent
animals like deer or monkeys know this information and they tell each other about it.
There are some plants like the ‘Bulls Horn Acacia Plant’ that produces spines (not thorns).
Spines are highly modified leaves which become prickly. The thorns on the roses are not
actually thorns just so you know. It has fascinated chemical ecologists for a long time. These
are wide spread in tropical forests and don’t seem to be producing alkaloids at all. They don’t do
it because they don’t have to because these trees have a symbiotic/mutalistic association with
ants that live inside them. When the plant experiences herbivory pressure the ants come out. It
does cost the plant some money i.e. sweetness/sugar/nectar that the ants eat internally. The ants
live inside so they are not eaten and they stand guard for the ‘Bulls Horn’. If you want to find
the function of something find an organism (mutant) that doesn’t have that feature and then you
might find the importance.
How much carbon/energy flowing through an eco system and how fast? We have a much more
rapid flow of biomass than any other terrestrial eco system.
The other domain is with bacteria that could live in extreme environments i.e. ‘Yellowstone
National Park’. These are water puddles near the boiling point (on overhead) and they go right
down to the earth’s crust. You can get a serious burn just by reaching in there. These contain
many chemicals that come up from the earth’s mantle. There is also a high amount of nickel,
zinc, titanium, chromium, etc. coming up from the mantle. There are highly specialized bacteria
in there as well. These are fairly young bacteria that are in here but the fact that we have them
now doesn’t mean we didn’t have those eons ago. What is interesting is what they eat which is
just about anything.
BGYC61H3F.October.20.2008 Lecture 6 2