couple of questions about FRAP experiments

[Serra Akinturk]

Hi all!

Currently i try to establish FRAP with my ECFP tagged protein which is distributed in cytoplasm of  neurons and i use LSM 510.

However i have some problems and i would love to get your valuable opinions.

Here are my questions:

1. How should i find the correct "laser iteration" to bleach the region that i want? Is there a calculation or a formula to find out the iteration of the laser when the laser is %100?

2. Even though my second question seems to be the same with the first one actually  it is a bit different. I don't always get  the same transfection efficiency in my cells. So how can i manage the iteration of my laser? Should i have always the same iteration value? But then i dont have efficient bleaching in cells where ECFP is highly expressed. (For example,last week i remember that in one cell i was able to do bleaching  with 10 iterations but in another cell i had to use 50 iteration). On the other hand the more i increase the iteration, bleaching time increases too. What is the standardization?

3. After the laser finishes the bleaching, cells always go out of focus and i lose the view. I checked many times that the cells had enough medium in the dish and they didn't get dry. But still i couldn't get rid of this problem. I think this happens because of the temperature change after bleaching. Any other suggestions?I need to overcome this...

4. I am also open to hear any "good FRAP paper" where i can learn more about the protocol.

Thanks so much in advance and i hope someone in this email group can help me.

Warmest regards,

Serra

[Arne Seitz]

Dear Serra,

 

concerning your questions:

 

1)      There is no formula available to calculate the best laser intensity for bleaching. As the correct intensity pretty much depends on the sample and the result you want obtain this is not really surprising. In general: the more fluorophores you bleach the higher the probability of inducing unwanted reactions like crosslinking or  even photodamage. If you are looking at fast diffusion you want to bleach as fast as possible. Thus you want to keep the number of iterations as low as possible.

2)       Changing the number of iterations will affect your results. If you want to compare your results you will have to keep the number of iterations constant.

3)      Diffusion is temperature dependant. Thus you want to do your experiments preferably at a constant temperature. If bleaching is heating up your sample you have to decrease the number of iterations or the laser power used for bleaching. Additionally you should make sure that the temperature is kept constant (for mammalian cells usually 37deg).

4)      At the following link you can find a nice tutorial for FRAP experiments.
http://www.embl.de/eamnet/html/teaching_modules.html

 

Best regards

Arne Seitz

---------------------------------------------------------------

Dr. Arne Seitz

Head of Bioimaging and Optics Platform (BIOP)

Swiss Institute of Technology (EPFL)
Faculty of Life Sciences
Station 15
CH-1015 Lausanne

Phone: [phone]
Fax:      [phone]

http://biop.epfl.ch/
---------------------------------------------------------------

 

From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Serra Akinturk
Sent: dimanche, 8. novembre 2009 23:47
To: [hidden email]
Subject: couple of questions about FRAP experiments

 

Hi all!

 

Currently i try to establish FRAP with my ECFP tagged protein which is distributed in cytoplasm of  neurons and i use LSM 510.

However i have some problems and i would love to get your valuable opinions.

 

Here are my questions:

 

1. How should i find the correct "laser iteration" to bleach the region that i want? Is there a calculation or a formula to find out the iteration of the laser when the laser is %100?

 

2. Even though my second question seems to be the same with the first one actually  it is a bit different. I don't always get  the same transfection efficiency in my cells. So how can i manage the iteration of my laser? Should i have always the same iteration value? But then i dont have efficient bleaching in cells where ECFP is highly expressed. (For example,last week i remember that in one cell i was able to do bleaching  with 10 iterations but in another cell i had to use 50 iteration). On the other hand the more i increase the iteration, bleaching time increases too. What is the standardization?

 

3. After the laser finishes the bleaching, cells always go out of focus and i lose the view. I checked many times that the cells had enough medium in the dish and they didn't get dry. But still i couldn't get rid of this problem. I think this happens because of the temperature change after bleaching. Any other suggestions?I need to overcome this...

 

4. I am also open to hear any "good FRAP paper" where i can learn more about the protocol.

 

Thanks so much in advance and i hope someone in this email group can help me.

 

Warmest regards,

 

Serra

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[leoncio vergara]

...from the biological point of view, working with cells that have a wild variation in protein expression is not very recomendable. It is possible the higher expression once lack physiological relevance. You may want to select a moderate range of expression levels, this would avoid biological variability and at the same time help solving the issue of having to change the number of iterarions too much.

...you probbaly know this, but another factor that affects the time for photobleaching is the size and shape of the ROI, obviously the larger the number of pixels the more time will take, but more important is the number of lines (ROI dimension in the Y direction) you are bleaching as this is the slow movement axis. Use similar size regions, as small as possible, specially in the Y axis.

Leoncio  

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Serra Akinturk
Sent: Sunday, November 08, 2009 4:47 PM
To: [hidden email]
Subject: couple of questions about FRAP experiments

Hi all!

Currently i try to establish FRAP with my ECFP tagged protein which is distributed in cytoplasm of  neurons and i use LSM 510.
However i have some problems and i would love to get your valuable opinions.

Here are my questions:

1. How should i find the correct "laser iteration" to bleach the region that i want? Is there a calculation or a formula to find out the iteration of the laser when the laser is %100?

2. Even though my second question seems to be the same with the first one actually  it is a bit different. I don't always get  the same transfection efficiency in my cells. So how can i manage the iteration of my laser? Should i have always the same iteration value? But then i dont have efficient bleaching in cells where ECFP is highly expressed. (For example,last week i remember that in one cell i was able to do bleaching  with 10 iterations but in another cell i had to use 50 iteration). On the other hand the more i increase the iteration, bleaching time increases too. What is the standardization?

3. After the laser finishes the bleaching, cells always go out of focus and i lose the view. I checked many times that the cells had enough medium in the dish and they didn't get dry. But still i couldn't get rid of this problem. I think this happens because of the temperature change after bleaching. Any other suggestions?I need to overcome this...

4. I am also open to hear any "good FRAP paper" where i can learn more about the protocol.

Thanks so much in advance and i hope someone in this email group can help me.

Warmest regards,

Serra

















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[John Oreopoulos]

This is not really a microscopy related question, but I figure there should be people here who would be able to answer this query. I have a friend from another lab who came to me last Friday and asked me if there was a simple experiment/demonstration that could be set up to demonstrate the concept of fluorescence to high school students. I couldn't think of one off the top of my head. The only thing that came to mind was the bit about using Fluorescein dye to make the Chicago river look green on St. Patrick's day, but I don't know if there's a cheap source of Floourscein out there or if it's safe to use with younger students. The only other thing I could recall was some basic experiment that involved pulling dyes from a commercial highlighter pen and showing that they are fluorescent somehow, but I can't remember much more than that. Basically, he needs to show that with some substance you can put light of one color in and get a different color back out. Didn't George Stokes originally discover fluorescence that way somehow? 

Lastly, one beautiful demonstration that I can remember was given by Professor David Jameson a couple of years ago at the Biophysical Society meeting where in his talk that detailed the history of fluorescence he reproduced a phenomenon that was observed long ago in ancient Mexico where the wood ("kidney wood") of a specific Mexican tree when dissolved in water created an amazing blue glow under UV light. I don't think it would be easy to get this wood in Canada, however. 

If anyone knows of a simple (and cheap) way to demonstrate fluorescence, please do let me know.

John Oreopoulos, BSc,

PhD Candidate

University of Toronto

Institute For Biomaterials and Biomedical Engineering

Centre For Studies in Molecular Imaging

Tel: W:416-946-5022

[Adele Vincent]

hi John

What about rocks instead of wood? Many minerals look very different under UV light and should be much easier to get your hands on.

cheers
Adele


John Oreopoulos wrote:

This is not really a microscopy related question, but I figure there should be people here who would be able to answer this query. I have a friend from another lab who came to me last Friday and asked me if there was a simple experiment/demonstration that could be set up to demonstrate the concept of fluorescence to high school students. I couldn't think of one off the top of my head. The only thing that came to mind was the bit about using Fluorescein dye to make the Chicago river look green on St. Patrick's day, but I don't know if there's a cheap source of Floourscein out there or if it's safe to use with younger students. The only other thing I could recall was some basic experiment that involved pulling dyes from a commercial highlighter pen and showing that they are fluorescent somehow, but I can't remember much more than that. Basically, he needs to show that with some substance you can put light of one color in and get a different color back out. Didn't George Stokes originally discover fluorescence that way somehow? 

Lastly, one beautiful demonstration that I can remember was given by Professor David Jameson a couple of years ago at the Biophysical Society meeting where in his talk that detailed the history of fluorescence he reproduced a phenomenon that was observed long ago in ancient Mexico where the wood ("kidney wood") of a specific Mexican tree when dissolved in water created an amazing blue glow under UV light. I don't think it would be easy to get this wood in Canada, however. 

If anyone knows of a simple (and cheap) way to demonstrate fluorescence, please do let me know.

John Oreopoulos, BSc,

PhD Candidate

University of Toronto

Institute For Biomaterials and Biomedical Engineering

Centre For Studies in Molecular Imaging

Tel: W:416-946-5022

[Christian-103]

John,

I would think that something like this would be called for:


https://unitednuclear.com/index.php?main_page=product_info&cPath=28_45&products_id=383


Also, 99% of all scorpions fluoresce and you can get UV flashlights for $3 US and you do NOT need live scorpions for them to fluoresce.  Fluorite is also quite cheap but works better under 385nm light, which is risky for children.

In a dark room, even simple "black light" flashlights will show whiteners in clothing. 

I think the trick is to make it simple with a dash of physics so that it sticks in their minds.

If you need help with the scorpion angle, just yell, I know folks across the border who might be able to help you out.

Christian

[Lloyd Donaldson]

Wood (lignin) will fluoresce with either UV or visible excitation. So will paper. Most coloured inks will fluoresce. Green leaves are also very fluorescent due to chlorophyll but I guess maybe green leaves are in short supply at this time of year in Canada. Pine or Spruce needles would do though.

 

 

Dr Lloyd Donaldson

Senior Scientist

Scion - Next Generation Biomaterials

49 Sala St. Rotorua

Private Bag 3020, Rotorua 3046

NEW ZEALAND

Ph: 64 7 343 5581

Fx: 64 7 343 5507

www.scionresearch.com

 

 

 

 

From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of John Oreopoulos
Sent: Tuesday, 10 November 2009 2:56 p.m.
To: [hidden email]
Subject: Demonstration of fluorescence for high school

 

This is not really a microscopy related question, but I figure there should be people here who would be able to answer this query. I have a friend from another lab who came to me last Friday and asked me if there was a simple experiment/demonstration that could be set up to demonstrate the concept of fluorescence to high school students. I couldn't think of one off the top of my head. The only thing that came to mind was the bit about using Fluorescein dye to make the Chicago river look green on St. Patrick's day, but I don't know if there's a cheap source of Floourscein out there or if it's safe to use with younger students. The only other thing I could recall was some basic experiment that involved pulling dyes from a commercial highlighter pen and showing that they are fluorescent somehow, but I can't remember much more than that. Basically, he needs to show that with some substance you can put light of one color in and get a different color back out. Didn't George Stokes originally discover fluorescence that way somehow? 

Lastly, one beautiful demonstration that I can remember was given by Professor David Jameson a couple of years ago at the Biophysical Society meeting where in his talk that detailed the history of fluorescence he reproduced a phenomenon that was observed long ago in ancient Mexico where the wood ("kidney wood") of a specific Mexican tree when dissolved in water created an amazing blue glow under UV light. I don't think it would be easy to get this wood in Canada, however. 

If anyone knows of a simple (and cheap) way to demonstrate fluorescence, please do let me know.

 

John Oreopoulos, BSc,

PhD Candidate

University of Toronto

Institute For Biomaterials and Biomedical Engineering

Centre For Studies in Molecular Imaging

 

Tel: W:416-946-5022

 

[Craig Brideau]

I second Adele's comments on minerals; many will fluoresce quite
beautifully under UV.  Also fluorescein will glow green under UV
excitation.  Basically get a low-powered UV wand light and some
fluorescent minerals, maybe a little vial of fluorescein (it's quite
safe, just don't drink it), and some white paper (the bleached paper
fibers will glow brightly) and maybe scribble with highlighters on
parts of the paper to show that glow as well.

Craig

On Tue, Nov 10, 2009 at 11:00 AM, Adele Vincent
<[hidden email]> wrote:

> hi John
>
> What about rocks instead of wood? Many minerals look very different under UV
> light and should be much easier to get your hands on.
>
> cheers
> Adele
>
>
> John Oreopoulos wrote:
>
> This is not really a microscopy related question, but I figure there should
> be people here who would be able to answer this query. I have a friend from
> another lab who came to me last Friday and asked me if there was a simple
> experiment/demonstration that could be set up to demonstrate the concept of
> fluorescence to high school students. I couldn't think of one off the top of
> my head. The only thing that came to mind was the bit about using
> Fluorescein dye to make the Chicago river look green on St. Patrick's day,
> but I don't know if there's a cheap source of Floourscein out there or if
> it's safe to use with younger students. The only other thing I could recall
> was some basic experiment that involved pulling dyes from a commercial
> highlighter pen and showing that they are fluorescent somehow, but I can't
> remember much more than that. Basically, he needs to show that with some
> substance you can put light of one color in and get a different color back
> out. Didn't George Stokes originally discover fluorescence that way
> somehow?
> Lastly, one beautiful demonstration that I can remember was given by
> Professor David Jameson a couple of years ago at the Biophysical Society
> meeting where in his talk that detailed the history of fluorescence he
> reproduced a phenomenon that was observed long ago in ancient Mexico where
> the wood ("kidney wood") of a specific Mexican tree when dissolved in water
> created an amazing blue glow under UV light. I don't think it would be easy
> to get this wood in Canada, however.
> If anyone knows of a simple (and cheap) way to demonstrate fluorescence,
> please do let me know.
>
> John Oreopoulos, BSc,
>
> PhD Candidate
>
> University of Toronto
>
> Institute For Biomaterials and Biomedical Engineering
>
> Centre For Studies in Molecular Imaging
>
> Tel: W:416-946-5022
>
>
> --
>
> Adele Vincent, PhD
>
> NHMRC Postdoctoral Research Fellow
>
> Laboratory of Molecular Neurobiology
>
> Menzies Research Institute
>
> Tasmania, Australia
>
> ph:  [phone]
>
> fax: [phone]
>
> Mailing address:
>
> Private Bag 24
>
> University of Tasmania
>
> TAS 7001
>
> Australia

[Dave Tieman]

Assuming that you want to demo fluorescence, and not necessarily how we
use it:  Get a green laser pointer for excitation and a red transparency
filter that does a reasonable job of blocking the excitation frequency.
Point the laser at objects such as hot pink warning signs and yellow
tennis balls that often have a very broad emission peak.  On
non-fluorescing objects, you can show that the filter blocks the reflected
light, but does not block the light from fluorescing objects. It can be
fun to try a variety of objects around the room.

dave

 > This is not really a microscopy related question, but I figure there

> should be people here who would be able to answer this query. I have
> a friend from another lab who came to me last Friday and asked me if
> there was a simple experiment/demonstration that could be set up to
> demonstrate the concept of fluorescence to high school students. I
> couldn't think of one off the top of my head. The only thing that
> came to mind was the bit about using Fluorescein dye to make the
> Chicago river look green on St. Patrick's day, but I don't know if
> there's a cheap source of Floourscein out there or if it's safe to
> use with younger students. The only other thing I could recall was
> some basic experiment that involved pulling dyes from a commercial
> highlighter pen and showing that they are fluorescent somehow, but I
> can't remember much more than that. Basically, he needs to show that
> with some substance you can put light of one color in and get a
> different color back out. Didn't George Stokes originally discover
> fluorescence that way somehow?
> Lastly, one beautiful demonstration that I can remember was given by
> Professor David Jameson a couple of years ago at the Biophysical
> Society meeting where in his talk that detailed the history of
> fluorescence he reproduced a phenomenon that was observed long ago in
> ancient Mexico where the wood ("kidney wood") of a specific Mexican
> tree when dissolved in water created an amazing blue glow under UV
> light. I don't think it would be easy to get this wood in Canada,
> however.
> If anyone knows of a simple (and cheap) way to demonstrate
> fluorescence, please do let me know.
>
>
> John Oreopoulos, BSc,
> PhD Candidate
> University of Toronto
> Institute For Biomaterials and Biomedical Engineering
> Centre For Studies in Molecular Imaging
>
> Tel: W:416-946-5022
>
>
>

[Johnson, Iain-2]

My favorite is to use a solution of (very cheap) rhodamine 6G in water in a 500 ml (or bigger) cube media bottle.   Excite the fluorescence using a green (532 nm) laser pointer.  Dilute the dye down till there is at least some transmission of the excitation light out of the back of the bottle that can be projected on a card.  So now you have green light going in and less coming out the back with yellow fluorescence across the excitation path.  The square media bottle is to avoid getting weird reflections from the laser pointer off a cylindrical surface.  Probably best to write "do not drink" on the bottle (high school students can get quite creative when you're not looking).

 

Some more "advanced" demos you can do with this include switching to a red laser pointer to demonstrate the wavelength specificity (no fluorescence with 635 nm excitation) and dropping coffee creamer into the solution to demonstrate attenuation due to scattering.

 

Iain 

---

From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of John Oreopoulos
Sent: Monday, November 09, 2009 5:56 PM
To: [hidden email]
Subject: Demonstration of fluorescence for high school

This is not really a microscopy related question, but I figure there should be people here who would be able to answer this query. I have a friend from another lab who came to me last Friday and asked me if there was a simple experiment/demonstration that could be set up to demonstrate the concept of fluorescence to high school students. I couldn't think of one off the top of my head. The only thing that came to mind was the bit about using Fluorescein dye to make the Chicago river look green on St. Patrick's day, but I don't know if there's a cheap source of Floourscein out there or if it's safe to use with younger students. The only other thing I could recall was some basic experiment that involved pulling dyes from a commercial highlighter pen and showing that they are fluorescent somehow, but I can't remember much more than that. Basically, he needs to show that with some substance you can put light of one color in and get a different color back out. Didn't George Stokes originally discover fluorescence that way somehow? 

Lastly, one beautiful demonstration that I can remember was given by Professor David Jameson a couple of years ago at the Biophysical Society meeting where in his talk that detailed the history of fluorescence he reproduced a phenomenon that was observed long ago in ancient Mexico where the wood ("kidney wood") of a specific Mexican tree when dissolved in water created an amazing blue glow under UV light. I don't think it would be easy to get this wood in Canada, however. 

If anyone knows of a simple (and cheap) way to demonstrate fluorescence, please do let me know.

John Oreopoulos, BSc,

PhD Candidate

University of Toronto

Institute For Biomaterials and Biomedical Engineering

Centre For Studies in Molecular Imaging

Tel: W:416-946-5022

[Vladimir Ghukasyan-2]

In case of UV-light availability, the fluorescence could be
demonstrated on simple tonic. That was the very first demonstration of
fluorescence historically.


On Tue, Nov 10, 2009 at 10:21 AM, Craig Brideau <[hidden email]> wrote:

> I second Adele's comments on minerals; many will fluoresce quite
> beautifully under UV.  Also fluorescein will glow green under UV
> excitation.  Basically get a low-powered UV wand light and some
> fluorescent minerals, maybe a little vial of fluorescein (it's quite
> safe, just don't drink it), and some white paper (the bleached paper
> fibers will glow brightly) and maybe scribble with highlighters on
> parts of the paper to show that glow as well.
>
> Craig
>
> On Tue, Nov 10, 2009 at 11:00 AM, Adele Vincent
> <[hidden email]> wrote:
>> hi John
>>
>> What about rocks instead of wood? Many minerals look very different under UV
>> light and should be much easier to get your hands on.
>>
>> cheers
>> Adele
>>
>>
>> John Oreopoulos wrote:
>>
>> This is not really a microscopy related question, but I figure there should
>> be people here who would be able to answer this query. I have a friend from
>> another lab who came to me last Friday and asked me if there was a simple
>> experiment/demonstration that could be set up to demonstrate the concept of
>> fluorescence to high school students. I couldn't think of one off the top of
>> my head. The only thing that came to mind was the bit about using
>> Fluorescein dye to make the Chicago river look green on St. Patrick's day,
>> but I don't know if there's a cheap source of Floourscein out there or if
>> it's safe to use with younger students. The only other thing I could recall
>> was some basic experiment that involved pulling dyes from a commercial
>> highlighter pen and showing that they are fluorescent somehow, but I can't
>> remember much more than that. Basically, he needs to show that with some
>> substance you can put light of one color in and get a different color back
>> out. Didn't George Stokes originally discover fluorescence that way
>> somehow?
>> Lastly, one beautiful demonstration that I can remember was given by
>> Professor David Jameson a couple of years ago at the Biophysical Society
>> meeting where in his talk that detailed the history of fluorescence he
>> reproduced a phenomenon that was observed long ago in ancient Mexico where
>> the wood ("kidney wood") of a specific Mexican tree when dissolved in water
>> created an amazing blue glow under UV light. I don't think it would be easy
>> to get this wood in Canada, however.
>> If anyone knows of a simple (and cheap) way to demonstrate fluorescence,
>> please do let me know.
>>
>> John Oreopoulos, BSc,
>>
>> PhD Candidate
>>
>> University of Toronto
>>
>> Institute For Biomaterials and Biomedical Engineering
>>
>> Centre For Studies in Molecular Imaging
>>
>> Tel: W:416-946-5022
>>
>>
>> --
>>
>> Adele Vincent, PhD
>>
>> NHMRC Postdoctoral Research Fellow
>>
>> Laboratory of Molecular Neurobiology
>>
>> Menzies Research Institute
>>
>> Tasmania, Australia
>>
>> ph:  [phone]
>>
>> fax: [phone]
>>
>> Mailing address:
>>
>> Private Bag 24
>>
>> University of Tasmania
>>
>> TAS 7001
>>
>> Australia
>

[John Oreopoulos]

Thank you all for the excellent suggestions so far.

John

On 9-Nov-09, at 10:00 PM, Vladimir Gukassyan wrote:

> In case of UV-light availability, the fluorescence could be
> demonstrated on simple tonic. That was the very first demonstration of
> fluorescence historically.
>
>
> On Tue, Nov 10, 2009 at 10:21 AM, Craig Brideau  
> <[hidden email]> wrote:
>> I second Adele's comments on minerals; many will fluoresce quite
>> beautifully under UV.  Also fluorescein will glow green under UV
>> excitation.  Basically get a low-powered UV wand light and some
>> fluorescent minerals, maybe a little vial of fluorescein (it's quite
>> safe, just don't drink it), and some white paper (the bleached paper
>> fibers will glow brightly) and maybe scribble with highlighters on
>> parts of the paper to show that glow as well.
>>
>> Craig
>>
>> On Tue, Nov 10, 2009 at 11:00 AM, Adele Vincent
>> <[hidden email]> wrote:
>>> hi John
>>>
>>> What about rocks instead of wood? Many minerals look very  
>>> different under UV
>>> light and should be much easier to get your hands on.
>>>
>>> cheers
>>> Adele
>>>
>>>
>>> John Oreopoulos wrote:
>>>
>>> This is not really a microscopy related question, but I figure  
>>> there should
>>> be people here who would be able to answer this query. I have a  
>>> friend from
>>> another lab who came to me last Friday and asked me if there was  
>>> a simple
>>> experiment/demonstration that could be set up to demonstrate the  
>>> concept of
>>> fluorescence to high school students. I couldn't think of one off  
>>> the top of
>>> my head. The only thing that came to mind was the bit about using
>>> Fluorescein dye to make the Chicago river look green on St.  
>>> Patrick's day,
>>> but I don't know if there's a cheap source of Floourscein out  
>>> there or if
>>> it's safe to use with younger students. The only other thing I  
>>> could recall
>>> was some basic experiment that involved pulling dyes from a  
>>> commercial
>>> highlighter pen and showing that they are fluorescent somehow,  
>>> but I can't
>>> remember much more than that. Basically, he needs to show that  
>>> with some
>>> substance you can put light of one color in and get a different  
>>> color back
>>> out. Didn't George Stokes originally discover fluorescence that way
>>> somehow?
>>> Lastly, one beautiful demonstration that I can remember was given by
>>> Professor David Jameson a couple of years ago at the Biophysical  
>>> Society
>>> meeting where in his talk that detailed the history of  
>>> fluorescence he
>>> reproduced a phenomenon that was observed long ago in ancient  
>>> Mexico where
>>> the wood ("kidney wood") of a specific Mexican tree when  
>>> dissolved in water
>>> created an amazing blue glow under UV light. I don't think it  
>>> would be easy
>>> to get this wood in Canada, however.
>>> If anyone knows of a simple (and cheap) way to demonstrate  
>>> fluorescence,
>>> please do let me know.
>>>
>>> John Oreopoulos, BSc,
>>>
>>> PhD Candidate
>>>
>>> University of Toronto
>>>
>>> Institute For Biomaterials and Biomedical Engineering
>>>
>>> Centre For Studies in Molecular Imaging
>>>
>>> Tel: W:416-946-5022
>>>
>>>
>>> --
>>>
>>> Adele Vincent, PhD
>>>
>>> NHMRC Postdoctoral Research Fellow
>>>
>>> Laboratory of Molecular Neurobiology
>>>
>>> Menzies Research Institute
>>>
>>> Tasmania, Australia
>>>
>>> ph:  [phone]
>>>
>>> fax: [phone]
>>>
>>> Mailing address:
>>>
>>> Private Bag 24
>>>
>>> University of Tasmania
>>>
>>> TAS 7001
>>>
>>> Australia
>>

[Barbara Foster]

Hi, John

There is one really neat and absolutely graphic demo that is safe for any lab.  And you can really set the kids up in advance by asking them, "On the way to class today, did anyone see the grass fluorescing red?"  The kids will just giggle because everyone KNOWS that grass is green.

The experiment is simple:  just look at any leaf (grass, plant, tree) in regular light, then look at it under the fluorescent microscope with any green excitation/red emission filter set.  The ones used for Rhodamine are great.  The chloroplasts in the grass will fluoresce bright red. 

This is a great time to bring up the subject with the kids about the spectrum, the spectrum of sunlight, and reflected color versus fluorescently excited emissions.  There is LOTS of science in this one simple experiment and the kids will never forget it. 

By the way, the normal H&E stained preps (ex: Kidney), also work really well, too.  And it's neat to look at them with different filter sets to see the difference in fluorescence.

If you want a slightly more challenging experiment, you colleague can see if he can get an old CRT type color TV tube.  It's been more than 25 years since I've gone through this exercise, so let me if I can remember all the steps:
a. You need to have someone crack the tube to release the vacuum under controlled conditions, otherwise it could be very dangerous. 
b. Then, you need to carefully chip around the edge of the front panel to remove the actual screen.
c. It seems to me that there might be a black coating that can be peeled off, exposing the phosphors.
d. Cut a piece of Scotch tape about 1.5" long.  Place about 1" of the tape, sticky side down, over the phosphors.  Use the other 1/2" as a "handle". 
e. Using a tongue depressor, carefully stroke the tape to transfer the phosphors from the inside of the screen to the tape.
f.  Carefully peel back the tape and lay it, still sticky side down, on a microscope slide
g. Observe under a fluorescent microscope with a variety of filter cubes. (UV excitation, Blue, Green).  The different phosphors will fluoresce differently with each filter cube. 
h. When completed, dispose of the rest of the TV screen according to local regulations.

I think I've got all the steps right. We did this as part of a New York Microscopical/Royal Microscopical Course at U Mass/Amherst years ago and I STILL have my taped slide. 

One thing more: many minerals fluoresce, often revealing components that are "invisible" under normal white light.  A simple UV light which can be obtained at some science and/or party stores is sufficient.  But that's a WHOLE nother story!

I hope this helps your friend.

Best regards,
Barbara Foster, President and Sr. Consultant

Microscopy/Microscopy Education
7101 Royal Glen Trail, Suite A
McKinney TX 75070
P: [phone]  Skype: fostermme
W: www.MicroscopyEducation.com

NEWS! Visit the NEW and IMPROVED www.MicroscopyEducation.com! And don't forget:  MME is now scheduling customized, on-site courses for 2010.  Call me for a free assessment and quote.
At 07:04 PM 11/9/2009, John Oreopoulos wrote:

This is not really a microscopy related question, but I figure there should be people here who would be able to answer this query. I have a friend from another lab who came to me last Friday and asked me if there was a simple experiment/demonstration that could be set up to demonstrate the concept of fluorescence to high school students. I couldn't think of one off the top of my head. The only thing that came to mind was the bit about using Fluorescein dye to make the Chicago river look green on St. Patrick's day, but I don't know if there's a cheap source of Floourscein out there or if it's safe to use with younger students. The only other thing I could recall was some basic experiment that involved pulling dyes from a commercial highlighter pen and showing that they are fluorescent somehow, but I can't remember much more than that. Basically, he needs to show that with some substance you can put light of one color in and get a different color back out. Didn't George Stokes originally discover fluorescence that way somehow?
Lastly, one beautiful demonstration that I can remember was given by Professor David Jameson a couple of years ago at the Biophysical Society meeting where in his talk that detailed the history of fluorescence he reproduced a phenomenon that was observed long ago in ancient Mexico where the wood ("kidney wood") of a specific Mexican tree when dissolved in water created an amazing blue glow under UV light. I don't think it would be easy to get this wood in Canada, however.
If anyone knows of a simple (and cheap) way to demonstrate fluorescence, please do let me know.


John Oreopoulos, BSc,

PhD Candidate

University of Toronto

Institute For Biomaterials and Biomedical Engineering

Centre For Studies in Molecular Imaging


Tel: W:416-946-5022

[Dale Callaham]

John,

This has nothing to do with microscopy but it doesn't involve
"chemicals" either so it may be easier to deal with in a HS. Get a
bottle of Lysol - I'm looking at my bottle of "Lemon Breeze All-Purpose
3-in-1 Dilutable". Either the concentrate or a modest dilution, if held
close to a standard "white" fluorescent tube (tube or compact style)
will show  nice "fluorescein" green at the top where the light is
absorbed, and the green fades a bit below the surface of the solution as
the blue-UV has been absorbed. I'm sure the UV flashlights or a
blacklight poster (BLB (blacklight-blue) bulb will be more dramatic. A
beam of sunlight works too - oh, I forgot - it's Canada!

Cheers!

Dale

John Oreopoulos wrote:

> This is not really a microscopy related question, but I figure there
> should be people here who would be able to answer this query. I have a
> friend from another lab who came to me last Friday and asked me if there
> was a simple experiment/demonstration that could be set up to
> demonstrate the concept of fluorescence to high school students. I
> couldn't think of one off the top of my head. The only thing that came
> to mind was the bit about using Fluorescein dye to make the Chicago
> river look green on St. Patrick's day, but I don't know if there's a
> cheap source of Floourscein out there or if it's safe to use with
> younger students. The only other thing I could recall was some basic
> experiment that involved pulling dyes from a commercial highlighter pen
> and showing that they are fluorescent somehow, but I can't remember much
> more than that. Basically, he needs to show that with some substance you
> can put light of one color in and get a different color back out. Didn't
> George Stokes originally discover fluorescence that way somehow?
> Lastly, one beautiful demonstration that I can remember was given by
> Professor David Jameson a couple of years ago at the Biophysical Society
> meeting where in his talk that detailed the history of fluorescence he
> reproduced a phenomenon that was observed long ago in ancient Mexico
> where the wood ("kidney wood") of a specific Mexican tree when dissolved
> in water created an amazing blue glow under UV light. I don't think it
> would be easy to get this wood in Canada, however.
> If anyone knows of a simple (and cheap) way to demonstrate fluorescence,
> please do let me know.
>
>
> John Oreopoulos, BSc,
>
> PhD Candidate
>
> University of Toronto
>
> Institute For Biomaterials and Biomedical Engineering
>
> Centre For Studies in Molecular Imaging
>
>
> Tel: W:416-946-5022
>
>
>

[John Oreopoulos]

Another great idea!
Okay now, we do get lots of light up here in Canada contrary to what  
most people think. In fact, it was a balmy 18 degrees C in Toronto  
today and yesterday. Not bad for November. Now back to ice fishing in  
my igloo.

John

On 9-Nov-09, at 11:21 PM, Dale Callaham wrote:

> John,
>
> This has nothing to do with microscopy but it doesn't involve  
> "chemicals" either so it may be easier to deal with in a HS. Get a  
> bottle of Lysol - I'm looking at my bottle of "Lemon Breeze All-
> Purpose 3-in-1 Dilutable". Either the concentrate or a modest  
> dilution, if held close to a standard "white" fluorescent tube  
> (tube or compact style) will show  nice "fluorescein" green at the  
> top where the light is absorbed, and the green fades a bit below  
> the surface of the solution as the blue-UV has been absorbed. I'm  
> sure the UV flashlights or a blacklight poster (BLB (blacklight-
> blue) bulb will be more dramatic. A beam of sunlight works too -  
> oh, I forgot - it's Canada!
>
> Cheers!
>
> Dale
>
> John Oreopoulos wrote:
>> This is not really a microscopy related question, but I figure  
>> there should be people here who would be able to answer this  
>> query. I have a friend from another lab who came to me last Friday  
>> and asked me if there was a simple experiment/demonstration that  
>> could be set up to demonstrate the concept of fluorescence to high  
>> school students. I couldn't think of one off the top of my head.  
>> The only thing that came to mind was the bit about using  
>> Fluorescein dye to make the Chicago river look green on St.  
>> Patrick's day, but I don't know if there's a cheap source of  
>> Floourscein out there or if it's safe to use with younger  
>> students. The only other thing I could recall was some basic  
>> experiment that involved pulling dyes from a commercial  
>> highlighter pen and showing that they are fluorescent somehow, but  
>> I can't remember much more than that. Basically, he needs to show  
>> that with some substance you can put light of one color in and get  
>> a different color back out. Didn't George Stokes originally  
>> discover fluorescence that way somehow? Lastly, one beautiful  
>> demonstration that I can remember was given by Professor David  
>> Jameson a couple of years ago at the Biophysical Society meeting  
>> where in his talk that detailed the history of fluorescence he  
>> reproduced a phenomenon that was observed long ago in ancient  
>> Mexico where the wood ("kidney wood") of a specific Mexican tree  
>> when dissolved in water created an amazing blue glow under UV  
>> light. I don't think it would be easy to get this wood in Canada,  
>> however. If anyone knows of a simple (and cheap) way to  
>> demonstrate fluorescence, please do let me know.
>> John Oreopoulos, BSc,
>> PhD Candidate
>> University of Toronto
>> Institute For Biomaterials and Biomedical Engineering
>> Centre For Studies in Molecular Imaging
>> Tel: W:416-946-5022

[Guy Cox]

My favourite demo is with tonic water.  I have a little UV LED key-chain torch which I can palm, and I turn the room lights off and pour myself a drink.  It really looks quite startling, and I've heard gasps as I drink the glowing blue liquid!  Then I say, "Very nice, but it needs a pinch of salt" and shake a salt-cellar into the glass - the fluorescence goes out like a light.  This make the point that fluorescence depends on the chemical environment.  I don't usually drink it after adding the salt, though.  

Fluorescein works well - a solution that is so week as to be nearly colourless fluoesces very brightly with a blue keychain LED (it's always worth souveniering those conference give-aways!).  Fluorescein is quite cheap (eg from Sigma), and totally non-toxic. Even safe to drink.  Rhodamine, on the other hand, isn't regarded as quite so safe.

I also have a if piece of titanium sapphire (a melt that was rejected for laser user because of bubbles).  That works well with a green laser pointer.

The advantage of having 3 different samples is that you can demonstrate Stokes Shift - blue will not excite the tonic, green will not excite the fluorescein, etc.    

                                           Guy



Optical Imaging Techniques in Cell Biology
by Guy Cox    CRC Press / Taylor & Francis
    http://www.guycox.com/optical.htm
______________________________________________
Associate Professor Guy Cox, MA, DPhil(Oxon)
Electron Microscope Unit, Madsen Building F09,
University of Sydney, NSW 2006
______________________________________________
Phone [phone]     Fax [phone]
Mobile [phone]
______________________________________________
     http://www.guycox.net
-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Vladimir Gukassyan
Sent: Tuesday, 10 November 2009 2:00 PM
To: [hidden email]
Subject: Re: Demonstration of fluorescence for high school

In case of UV-light availability, the fluorescence could be demonstrated on simple tonic. That was the very first demonstration of fluorescence historically.


On Tue, Nov 10, 2009 at 10:21 AM, Craig Brideau <[hidden email]> wrote:

> I second Adele's comments on minerals; many will fluoresce quite
> beautifully under UV.  Also fluorescein will glow green under UV
> excitation.  Basically get a low-powered UV wand light and some
> fluorescent minerals, maybe a little vial of fluorescein (it's quite
> safe, just don't drink it), and some white paper (the bleached paper
> fibers will glow brightly) and maybe scribble with highlighters on
> parts of the paper to show that glow as well.
>
> Craig
>
> On Tue, Nov 10, 2009 at 11:00 AM, Adele Vincent
> <[hidden email]> wrote:
>> hi John
>>
>> What about rocks instead of wood? Many minerals look very different
>> under UV light and should be much easier to get your hands on.
>>
>> cheers
>> Adele
>>
>>
>> John Oreopoulos wrote:
>>
>> This is not really a microscopy related question, but I figure there
>> should be people here who would be able to answer this query. I have
>> a friend from another lab who came to me last Friday and asked me if
>> there was a simple experiment/demonstration that could be set up to
>> demonstrate the concept of fluorescence to high school students. I
>> couldn't think of one off the top of my head. The only thing that
>> came to mind was the bit about using Fluorescein dye to make the
>> Chicago river look green on St. Patrick's day, but I don't know if
>> there's a cheap source of Floourscein out there or if it's safe to
>> use with younger students. The only other thing I could recall was
>> some basic experiment that involved pulling dyes from a commercial
>> highlighter pen and showing that they are fluorescent somehow, but I
>> can't remember much more than that. Basically, he needs to show that
>> with some substance you can put light of one color in and get a
>> different color back out. Didn't George Stokes originally discover fluorescence that way somehow?
>> Lastly, one beautiful demonstration that I can remember was given by
>> Professor David Jameson a couple of years ago at the Biophysical
>> Society meeting where in his talk that detailed the history of
>> fluorescence he reproduced a phenomenon that was observed long ago in
>> ancient Mexico where the wood ("kidney wood") of a specific Mexican
>> tree when dissolved in water created an amazing blue glow under UV
>> light. I don't think it would be easy to get this wood in Canada, however.
>> If anyone knows of a simple (and cheap) way to demonstrate
>> fluorescence, please do let me know.
>>
>> John Oreopoulos, BSc,
>>
>> PhD Candidate
>>
>> University of Toronto
>>
>> Institute For Biomaterials and Biomedical Engineering
>>
>> Centre For Studies in Molecular Imaging
>>
>> Tel: W:416-946-5022
>>
>>
>> --
>>
>> Adele Vincent, PhD
>>
>> NHMRC Postdoctoral Research Fellow
>>
>> Laboratory of Molecular Neurobiology
>>
>> Menzies Research Institute
>>
>> Tasmania, Australia
>>
>> ph:  [phone]
>>
>> fax: [phone]
>>
>> Mailing address:
>>
>> Private Bag 24
>>
>> University of Tasmania
>>
>> TAS 7001
>>
>> Australia
>

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.702 / Virus Database: 270.14.50/2481 - Release Date: 11/10/09 06:40:00

[Patrick Van Oostveldt]

Dear,

Uranyl minerals are also fluorescent by UV excitation. In older times  
these glasses were used as UV-filters type GG.
These glasses are also very good in showing the effect of numerical  
aperture and illumination paths. However the they emit some radiation  
but at very low dose. The are very fluorescent and show no bleaching.  
The fluorescence intensity is dependent on temperature (1% decrease  
per degree C). These glasses were used in fluoro-spectrophotometers to  
adjust set-up.

Patrick Van Oostveldt


  Quoting Adele Vincent <[hidden email]>:

> hi John
>
> What about rocks instead of wood? Many minerals look very different
> under UV light and should be much easier to get your hands on.
>
> cheers
> Adele
>
>
> John Oreopoulos wrote:
>> This is not really a microscopy related question, but I figure  
>> there should be people here who would be able to answer this query.  
>>  I have a friend from another lab who came to me last Friday and  
>> asked me if there was a simple experiment/demonstration that could  
>> be set up to demonstrate the concept of fluorescence to high school  
>>  students. I couldn't think of one off the top of my head. The only  
>>  thing that came to mind was the bit about using Fluorescein dye to  
>>  make the Chicago river look green on St. Patrick's day, but I  
>> don't  know if there's a cheap source of Floourscein out there or  
>> if it's  safe to use with younger students. The only other thing I  
>> could  recall was some basic experiment that involved pulling dyes  
>> from a  commercial highlighter pen and showing that they are  
>> fluorescent  somehow, but I can't remember much more than that.  
>> Basically, he  needs to show that with some substance you can put  
>> light of one  color in and get a different color back out. Didn't  
>> George Stokes  originally discover fluorescence that way somehow?  
>> Lastly, one  beautiful demonstration that I can remember was given  
>> by Professor  David Jameson a couple of years ago at the  
>> Biophysical Society  meeting where in his talk that detailed the  
>> history of fluorescence  he reproduced a phenomenon that was  
>> observed long ago in ancient  Mexico where the wood ("kidney wood")  
>> of a specific Mexican tree  when dissolved in water created an  
>> amazing blue glow under UV  light. I don't think it would be easy  
>> to get this wood in Canada,  however. If anyone knows of a simple  
>> (and cheap) way to demonstrate  fluorescence, please do let me know.
>>
>>
>> John Oreopoulos, BSc,
>>
>> PhD Candidate
>>
>> University of Toronto
>>
>> Institute For Biomaterials and Biomedical Engineering
>>
>> Centre For Studies in Molecular Imaging
>>
>>
>> Tel: W:416-946-5022
>>
>>
>>
>
> --
>
>
> Adele Vincent, PhD
>
> NHMRC Postdoctoral Research Fellow
>
> Laboratory of Molecular Neurobiology
>
> Menzies Research Institute
>
> Tasmania, Australia
>
>
> ph:  [phone]
>
> fax: [phone]
>
>
> Mailing address:
>
> Private Bag 24
>
> University of Tasmania
>
> TAS 7001
>
> Australia

--
Dep. Moleculaire Biotechnologie
Coupure links 653
B 9000 GENT

tel [phone]
fax [phone]

[Ricardo Figueroa]

How about using tonic water, quinine will fluoresce when exited with UV. A standard UV diode will work fine, however I must admit that a scorpion would be much more impressive.

/Ricardo

[Patrick Van Oostveldt]

Hi,

Please note that a lot of stamps and paper money show fluorescence in  
a very specific way. You can use it also in a microscope at low  
magnification.
After demonstration of the fluorescence you money or stamp still has  
its original value an can be used for further investments in your  
microscope set-up.

Bye

Patrick Van Oostveldt

Quoting John Oreopoulos <[hidden email]>:

> Another great idea!
> Okay now, we do get lots of light up here in Canada contrary to what
> most people think. In fact, it was a balmy 18 degrees C in Toronto
> today and yesterday. Not bad for November. Now back to ice fishing in
> my igloo.
>
> John
>
> On 9-Nov-09, at 11:21 PM, Dale Callaham wrote:
>
>> John,
>>
>> This has nothing to do with microscopy but it doesn't involve  
>> "chemicals" either so it may be easier to deal with in a HS. Get a  
>> bottle of Lysol - I'm looking at my bottle of "Lemon Breeze  
>> All-Purpose 3-in-1 Dilutable". Either the concentrate or a modest  
>> dilution, if held close to a standard "white" fluorescent tube  
>> (tube or compact style) will show  nice "fluorescein" green at the  
>> top where the light is absorbed, and the green fades a bit below  
>> the surface of the solution as the blue-UV has been absorbed. I'm  
>> sure the UV flashlights or a blacklight poster (BLB  
>> (blacklight-blue) bulb will be more dramatic. A beam of sunlight  
>> works too - oh, I forgot - it's Canada!
>>
>> Cheers!
>>
>> Dale
>>
>> John Oreopoulos wrote:
>>> This is not really a microscopy related question, but I figure  
>>> there should be people here who would be able to answer this  
>>> query. I have a friend from another lab who came to me last Friday  
>>>  and asked me if there was a simple experiment/demonstration that  
>>> could be set up to demonstrate the concept of fluorescence to high  
>>>  school students. I couldn't think of one off the top of my head.  
>>> The only thing that came to mind was the bit about using  
>>> Fluorescein dye to make the Chicago river look green on St.  
>>> Patrick's day, but I don't know if there's a cheap source of  
>>> Floourscein out there or if it's safe to use with younger  
>>> students. The only other thing I could recall was some basic  
>>> experiment that involved pulling dyes from a commercial  
>>> highlighter pen and showing that they are fluorescent somehow, but  
>>>  I can't remember much more than that. Basically, he needs to show  
>>>  that with some substance you can put light of one color in and  
>>> get  a different color back out. Didn't George Stokes originally  
>>> discover fluorescence that way somehow? Lastly, one beautiful  
>>> demonstration that I can remember was given by Professor David  
>>> Jameson a couple of years ago at the Biophysical Society meeting  
>>> where in his talk that detailed the history of fluorescence he  
>>> reproduced a phenomenon that was observed long ago in ancient  
>>> Mexico where the wood ("kidney wood") of a specific Mexican tree  
>>> when dissolved in water created an amazing blue glow under UV  
>>> light. I don't think it would be easy to get this wood in Canada,  
>>> however. If anyone knows of a simple (and cheap) way to  
>>> demonstrate fluorescence, please do let me know.
>>> John Oreopoulos, BSc,
>>> PhD Candidate
>>> University of Toronto
>>> Institute For Biomaterials and Biomedical Engineering
>>> Centre For Studies in Molecular Imaging
>>> Tel: W:416-946-5022

--
Dep. Moleculaire Biotechnologie
Coupure links 653
B 9000 GENT

tel [phone]
fax [phone]

[Keith Morris]

As well as the other excellent suggestions, check out suppliers for
teachers, e.g. sun-light detecting fluorescent beads [kid's bracelet kind] -
who are geared up for this sort of thing [i.e. cheap, works and relatively
safe].
http://www.teachersource.com/Ultraviolet/Ultraviolet/PortableUVLight.aspx
http://65.19.85.158/Ultraviolet/Ultraviolet.aspx

or in the UK [and ireland] e.g.
http://www.selectadna.co.uk/uv-lights.html?gclid=CKDU47HFgJ4CFVeY2AodcheQpA
http://www.purpleturtle.co.uk/acatalog/Safe_Sun_Protection__Monitoring_the_U
V_Level.html
http://www.teachersource.com/Images/UserDir/UV-AST.html
http://www.fashionblogsite.com/blogs/permalinks/5-2007/the-perfect-companion
-for-your-sunblock.php
http://www.labsupplies.ie/pp/Chemistry/Earth_Sciences/Ultraviolet_Detecting_
Beads_%28pack_of_500%29.html
http://www.starlab-astronomy.co.nz/uvbead.htm

The uV light source works well with my large rock slices that I got from
eBay [supplied ground thin on a glass slide, and as the lump of rock].

Regards

Keith

---------------------------------------------------------------------------
Dr Keith J. Morris,
Molecular Cytogenetics and Microscopy Core,
Laboratory 00/069 and 00/070,
The Wellcome Trust Centre for Human Genetics,
Roosevelt Drive,
Oxford  OX3 7BN,
United Kingdom.

Telephone:  [phone]
Email:  [hidden email]
Web-pages: http://www.well.ox.ac.uk/molecular-cytogenetics-and-microscopy

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On
Behalf Of Patrick Van Oostveldt
Sent: 10 November 2009 09:56
To: [hidden email]
Subject: Re: Demonstration of fluorescence for high school

Hi,

Please note that a lot of stamps and paper money show fluorescence in  
a very specific way. You can use it also in a microscope at low  
magnification.
After demonstration of the fluorescence you money or stamp still has  
its original value an can be used for further investments in your  
microscope set-up.

Bye

Patrick Van Oostveldt

Quoting John Oreopoulos <[hidden email]>:

> Another great idea!
> Okay now, we do get lots of light up here in Canada contrary to what
> most people think. In fact, it was a balmy 18 degrees C in Toronto
> today and yesterday. Not bad for November. Now back to ice fishing in
> my igloo.
>
> John
>
> On 9-Nov-09, at 11:21 PM, Dale Callaham wrote:
>
>> John,
>>
>> This has nothing to do with microscopy but it doesn't involve  
>> "chemicals" either so it may be easier to deal with in a HS. Get a  
>> bottle of Lysol - I'm looking at my bottle of "Lemon Breeze  
>> All-Purpose 3-in-1 Dilutable". Either the concentrate or a modest  
>> dilution, if held close to a standard "white" fluorescent tube  
>> (tube or compact style) will show  nice "fluorescein" green at the  
>> top where the light is absorbed, and the green fades a bit below  
>> the surface of the solution as the blue-UV has been absorbed. I'm  
>> sure the UV flashlights or a blacklight poster (BLB  
>> (blacklight-blue) bulb will be more dramatic. A beam of sunlight  
>> works too - oh, I forgot - it's Canada!
>>
>> Cheers!
>>
>> Dale
>>
>> John Oreopoulos wrote:
>>> This is not really a microscopy related question, but I figure  
>>> there should be people here who would be able to answer this  
>>> query. I have a friend from another lab who came to me last Friday  
>>>  and asked me if there was a simple experiment/demonstration that  
>>> could be set up to demonstrate the concept of fluorescence to high  
>>>  school students. I couldn't think of one off the top of my head.  
>>> The only thing that came to mind was the bit about using  
>>> Fluorescein dye to make the Chicago river look green on St.  
>>> Patrick's day, but I don't know if there's a cheap source of  
>>> Floourscein out there or if it's safe to use with younger  
>>> students. The only other thing I could recall was some basic  
>>> experiment that involved pulling dyes from a commercial  
>>> highlighter pen and showing that they are fluorescent somehow, but  
>>>  I can't remember much more than that. Basically, he needs to show  
>>>  that with some substance you can put light of one color in and  
>>> get  a different color back out. Didn't George Stokes originally  
>>> discover fluorescence that way somehow? Lastly, one beautiful  
>>> demonstration that I can remember was given by Professor David  
>>> Jameson a couple of years ago at the Biophysical Society meeting  
>>> where in his talk that detailed the history of fluorescence he  
>>> reproduced a phenomenon that was observed long ago in ancient  
>>> Mexico where the wood ("kidney wood") of a specific Mexican tree  
>>> when dissolved in water created an amazing blue glow under UV  
>>> light. I don't think it would be easy to get this wood in Canada,  
>>> however. If anyone knows of a simple (and cheap) way to  
>>> demonstrate fluorescence, please do let me know.
>>> John Oreopoulos, BSc,
>>> PhD Candidate
>>> University of Toronto
>>> Institute For Biomaterials and Biomedical Engineering
>>> Centre For Studies in Molecular Imaging
>>> Tel: W:416-946-5022

--
Dep. Moleculaire Biotechnologie
Coupure links 653
B 9000 GENT

tel [phone]
fax [phone]