Richard,
The spectra for Texas Red (TR) are available from Molecular Probes
<www.probes.com>. Looking at this plot, I was able to generate the
following table.
wavelength (nm) | absorbance (%)
(Ar) 488 | 3
(Ar) 514 | 9
(Ar) 528 | 15
(Kr) 568 | 44
(max) 594 | 100
619 | 27
(HeNe) 633 | 5
TR is typically excited by either the 568 nm line from a krypton laser or
an appropriate wavelength from a tunable dye laser. Cells labeled with TR
are not noticably excited by 488 nm argon (but "Texas Red" beads don't
mind) or 633 nm HeNe. When I tune my dye laser from 588 nm (upper limit of
PE filter) to 619 nm (lower limit of TR filter) the TR signal falls off
rapidly, and TR fluorescence is not detected well before 619 nm excitation
(actually, we use sulforhodamine instead of TR). So I would not expect to
see a TR signal with 514 nm excitation, nor with 528 nm excitation (special
optics required) based on the above table.
Your investigator may find it less expensive to change fluorochromes than
to buy you (a) a dye laser or (b) a krypton laser and 3rd laser mount. If
she needs a dye that is excited by your 2nd laser (most likely in UV), we
have found that cascade blue (Molecular Probes) works well with argon UV
excitation with "bright" antibodies like CD8.
>I have an investigator that has designed an experiment that lends itself to
>using Texas Red as the fluorochrome of choice. She has acquired an antibody
>congugated with Texas Red for an assay that is specific to her needs.
>Unfortunately, she failed to inform the operator of our Facstar Plus about
>her choice of fluorochrome. Our instrument is equipped with a dual laser
>system with one laser limited to a single 488nm line. The second laser has
>multi-line capabilities, but can only be tuned to the maximum of 514nm. The
>optimal excitation wavelength for Texas Red as I have discovered is 590nm.
>I have discussed this with her, but she insists on analysis at 514nm. I
>cannot envision getting any suitable results. Does anyone out there have
>any experience with Texas Red that could shed any light on this problem?
>
>Thank You
>
>Richard J. Jaramillo
>LRRI
>Albuquerque,NM
>Ph(505)845-1217 Fax(505)845-1198
>rjaramil@lrri.org
Good luck,
Eric
/\/\/\_ Eric Van Buren, aa9080@wayne.edu
\ \ \ Karmanos Cancer Institute and Immunology & Microbiology
\_^_/ Wayne State University, Detroit, Michigan, USA
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