slide projector

Marja E. Coady mcoady at generation.net
Tue Jan 14 19:43:56 EST 1997


Christoph Reichel wrote:
> 
> As I guessed there is a high interest in the issue of using a slide
> projector (or something similiar simple) for the excitation of GFP. Since I
> have been asked by several interested colleques, whether I have received
> answer on my questions concerning excitation with a slide projector, I post
> this answer to the newsgroup:
>
	<rest deleted>

	I'd like to throw in my two cents on the use of slide projectors
for visualizing GFP.  We've done this for quite a while and I've a
couple
of small suggestions to make.  One is to consider not only which
excitation
wavelength to choose for the filter attached to the slide projector, but
also the size of the bandpass.  We use GFP when we inject DNA into
Xenopus
oocytes, which are about 1 mm in diameter and thus far too large for use
with a microscope.  We tried a few filters from Andover Technologies
(Salem, MA) and decided to go with the 400 nm filter with a wavelength
half-maximum of 40 nm (Cat #400FS40-50).  In our hands, this permitted
easy visualization of regular GFP as well as sufficient illumination
that we could make out the cells that were not fluorescent, making it
easy to separate the two.  For some uses, this may be essential.  In any 
event, filters can be purchased with half-maxima of 10 or 70 nm, I
believe.
	Another factor is the emission filter used.  I suspect (but
am not sure) that Kodak Wratten filters are similar to the type that
we purchased (Lee transparent green cellophane photography gel (Green
#122)).  In any case, the Lee gels can be purchased at most good 
photography shops and are surprisingly inexpensive to anyone who
purchases
scientific equipment.  This green gel is ideal for visualizing GFP
and is available in different sizes, to be attached to visors or glasses
as desired.  Do not let any industrious individual try to clean them
with alcohol!!!!! :-<
	Finally, it is useful to buy some inexpensive black cloth to
block light from the slide projector from interfering with visualizing
the GFP.  It is strongly advised that you put it up yourself and affix
some kind of sign so that nobody gets the bright idea to try to wrap it
around the slide projector, blocking the ventilation.  Yes, it does
happen.

Mike (no affiliation with the companies mentioned) Coady
GFTM
Universite de Montreal



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