I know this is an arcane topic, but has anyone done any work extracting and quantifying pigments from fish? I ask because I'm involved with a project to extract carotenoid pigments from scarlet shiners, Lythrurus fasciolaris. We have the protocol worked out to do TLC and ran it on the first two fish Monday; ideally we could do it on HPLC but we don't have easy access to one at the moment, and I don't have the $30,000 to buy my own at the moment(!).
Any Experience With Pigment Extraction From Fish?
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, Apr 03 2007 06:30 PM
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#2
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Posted 03 April 2007 - 11:07 PM
(I am not a biologist or a chemist, so just ignore this if necessary.) I have a friend who is a chemist for the EPA and he used to do PCB measurements from Great Lakes fish. Quite a messy process involving carp and blenders. If this is similar to your research, I am sure he would be willing to answer questions.
#3
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Posted 05 April 2007 - 11:40 AM
(I am not a biologist or a chemist, so just ignore this if necessary.) I have a friend who is a chemist for the EPA and he used to do PCB measurements from Great Lakes fish. Quite a messy process involving carp and blenders. If this is similar to your research, I am sure he would be willing to answer questions.
You might check with Brady Porter at Duquesne (porterb@duq.edu). He did some work with snubnose darter pigments.
#4
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Posted 05 April 2007 - 02:45 PM
You might check with Brady Porter at Duquesne (porterb@duq.edu). He did some work with snubnose darter pigments.
Brady's my main man and inspiration for this project, and the only other person I know who's done it. Extracting the pigments is almost easy; the challenge is to calculate the surface area of a darter............
#5
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Posted 05 April 2007 - 03:13 PM
This is just a total shot in the dark idea that popped into my head....but is there a way you calculate, or back calculate surface area (or 1/2 SA) of a small fish by making a negative cast/mold of it? Don't laugh too hard...
#6
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Posted 05 April 2007 - 05:25 PM
This is just a total shot in the dark idea that popped into my head....but is there a way you calculate, or back calculate surface area (or 1/2 SA) of a small fish by making a negative cast/mold of it? Don't laugh too hard...
No, I'm not laughing. My colleague suggested wrapping a fish's body tightly in just enough saranwrap to cover the body, weigh the saranwrap, and plug that weight in a standard curve of saranwrap weight vs. area calculated from rectilinear sheets of saranwrap. There's also a recent journal article forwarded to me by Dave Neely in the Journal of Fish Disease that does a similar calculation from wrapping Bounty paper towels around a fish (and the article explicitly says Bounty). So one of those approaches will probably work for us with scarlet shiners, I hope.
#9
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Posted 05 April 2007 - 06:26 PM
The paper towel or Saran Wrap will fold. How do you account for that? Do you trim it precisely? Wouldn't a paper towel harm the fish?
Well, we're dealing with fish that have already been euthanized so that isn't a problem. And the article authors claim that the Bounty (specifically!) won't fold, etc. The idea is to trim it as precisely as possible, and also the various fins are trimmed off and measured separately. If you do this with several fish, say 5 - 8, you can establish a predictable relationship for a species such that if you know the length and mass of an individual you can predict its surface area with some reasonable accuracy.
#10
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Posted 05 April 2007 - 07:15 PM
I would approach that the same way you approach calculating the surface area of any mathematical solid. Use a thread or something and take measurements of the perimeter at equidistant points. Calculate the surface area for each segment and add 'em up. A little number crunching will tell you how close together the segments need to be in order to acheive the desired amount of accuracy. I wouldn't try to do that integral though - it could get messy!
Or you could rig a meat slicer, and make slices of the frozen fish and measure the perimeter of each slice. A meat slicer would give you consistent thickness and it would be variable to whatever extent you require. Kind of like a big microtome. Or maybe one of those egg slicers that cuts the egg into like 30 slices with one chop - something like that
Or you could rig a meat slicer, and make slices of the frozen fish and measure the perimeter of each slice. A meat slicer would give you consistent thickness and it would be variable to whatever extent you require. Kind of like a big microtome. Or maybe one of those egg slicers that cuts the egg into like 30 slices with one chop - something like that
#12
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Posted 05 April 2007 - 10:02 PM
ROTF!I would approach that the same way you approach calculating the surface area of any mathematical solid. Use a thread or something and take measurements of the perimeter at equidistant points. Calculate the surface area for each segment and add 'em up. A little number crunching will tell you how close together the segments need to be in order to acheive the desired amount of accuracy. I wouldn't try to do that integral though - it could get messy!
Or you could rig a meat slicer, and make slices of the frozen fish and measure the perimeter of each slice. A meat slicer would give you consistent thickness and it would be variable to whatever extent you require. Kind of like a big microtome. Or maybe one of those egg slicers that cuts the egg into like 30 slices with one chop - something like that
#14
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Posted 05 April 2007 - 10:20 PM
I have done something very similar but the with reptiles. HPLC and TLC worked fine, just solvent choice was slightly hard because of movement of two very similar compounds.
We're working with TLC since we don't have easy access to an HPLC at the moment. There are a lot of slightly different carotenoids, we're lumping beta-carotenoids together for sheer simplicity.
#17
Michael Wolfe
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Posted 05 April 2007 - 10:44 PM
Newton's Method for calculatiung the area of the darter hey irate... I could tell you were serious... what does that say about me? I actually think that since the prez's fish are going to be dead anyway, it would not really be a bad idea. But it would be a lot of work. Couldn't you also just skin the fish in quesiton and then lay the skin out on a small grid paper... count the grids that are coverd and get an answer... probably would not work for the head, which would have to be calculated or estimated differently... but would seem to work pretty easily for the body... at least as eaily as trying to wrap the fish in one layer of saran wrap...
A very simplified version of an integral.
Either write something worth reading or do something worth writing. - Benjamin Franklin
#19
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Posted 05 April 2007 - 11:11 PM
I'm thinking along the lines of gyotaku. Ink the fish and rub rice (grid) paper over it. Should allow for precise surface area calculations.
I was thinking about something similar, but since a fish's surface is non-deformable I see problems there. You could do something similar with individual slices, though. It would work at least as well as thread.
#20
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Posted 05 April 2007 - 11:26 PM
I was thinking about something similar, but since a fish's surface is non-deformable I see problems there. You could do something similar with individual slices, though. It would work at least as well as thread.
I agree with the meat slicer. Only problem would be losses in cutting and the tedious layout. Once losses were calculated you should expect repeatability but layout would be quite a hurdle to overcome.
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