Help an undergraduate student

Bob bbx107 at excite.com
Sun Mar 6 22:38:21 EST 2005


On Sun, 6 Mar 2005 19:19:07 -0500, "The_Warrior" <almahdi at magma.ca>
wrote:

>This is our final proposal, what do you guys think of it?
>
>Reductions in Light Production of Bioluminescent Bacteria Resulting From
>Metabolic Changes Caused by Aquatic Pollutants
>
>
>
>Introduction
>
>Bioluminescent bacteria can be found in symbiotic relationships with a
>variety of fish. These bacteria are capable of producing light, and often
>fish are found to take advantage of this. These light producing bacteria can
>be used by fish for a variety of reasons that may include attracting prey,
>startling predators, or reproduction.
>
>The production of light by bioluminescent species of bacteria is
>metabolically linked. Decreased metabolism results in decreased production
>of bioluminescent compounds.
>
>
>
>Purpose
>
>There will be two purposes for this experiment.
>
>1)      To isolate and identify (to at least the genera level)
>bioluminescent bacteria found in the scales of fish.
>
>2)      To determine the effect (if any) that a common environmental
>pollutant (such as PNP or DDT) will have on the metabolic activity of the
>isolated bioluminescent bacteria.
>


There is a lot of interesting stuff here; you will learn a lot from
working on this.

And you may become popular. Luminescent bacteria are fun. Plates of
them will glow for many days (though getting fainter and fainter, for
the reason you would suggest). Your classmates -- and others-- will
enjoy them. (You do need to dark adapt to be impressed, though.)

Miscellaneous comments...

The luminescent vibrios are often classified as genus Photobacterium.
I am not sure what the preferred current distinction is, but you will
see both names used a lot. (Your test kit may not distinguish Vibrio
and Photobacterium.)

Suggest that you survey a wide range of agents for their effect,
rather than focus on a small predetermined list. I am not sure why DDT
would have any effect at all (or if it did whether that effect would
have any relevance to common concerns about DDT). What is PNP??


Remember, you will need to be on your best safety behavior. By intent,
you are working with toxic chemicals.



There are interesting stories, which you may or may not want to get
into, but at least may want to be aware of...

One of the interesting things about luminescent bacteria is that they
glow only at high cell density. How they do this is well understood,
and proving to be of considerable interest beyond this particular
event. Look up "quorum sensing".

Firefly luminescence is used widely in molecular biology. It is
similar overall, but biochemically distinct from the bacteria
luminescence.


>
>
>Methods/Materials
>
>
>
>Isolation
>
>A fresh, untreated sample of fish with the skin intact will be collected.

No personal experience, but I'm told that if you fish in the ocean at
night, it is common to see that the fish glow. (You do realize that
you need fish from the ocean? (not fresh water)


bob






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