Phytoplankton and red laser
Marcus Reckermann (recker@ftz-west.uni-kiel.de)
Mon, 20 Oct 1997 16:33:13 +0000
Hello everybody out there in cyto-world!
I have a very specialized inquiry, but I hope there=B4s somebody out
there... We analyze phytoplankton with a BD FacsVantage, equipped
with an Enterprise II laser at 488nm, and a red HeNe laser at 633nm.
We trigger with red (=3Dchlorophyll auto-) fluorescence of the blue
laser which is collected at 675/20nm; now we have installed the red
laser, whose red fluorescence signals are collected at 660/20nm.
What we have observed in natural water samples from the North Sea is
a distinct group which shows very strong red fluorescence signals
when excited by the red laser. While the ratio of red fluorescence by
red excitation (RFR) to that by blue excitation (RFB) is virtually
the same for all other phytoplankton clusters (including our
laboratory cultures of various taxonomic groups), the ratio is much
higher for that specific group. It=B4s a small (2-4=B5m) flagellate which
shows no unusual fluorescence when excited by blue or green light by
epifluorescence microscopy. We have sorted it and hope to grow it in
culture to make an HPLC pigment examination. But until now they
don=B4t grow... My questions:
Has anybody seen something similar in natural samples or cultures?
What emits at 660/20nm when excited by 633nm? Presumably Chl.b and
phycocyanine (Hofstraat et al 1991, J. Fluor. 1(4), 249-265), but our
cultured algae bearing these pigments did not behave that way.
I know this is a very special problem, but maybe someone can help.
Cheers, marcus
______________________________________________
Dr. Marcus Reckermann
Research and Technology Center Westcoast (FTZ)
Hafentoern, D-25761 Buesum, Germany
E-Mail recker@ftz-west.uni-kiel.de
Tel. +49-(0)4834-604-204 or -212 or -261
Fax. +49-(0)4834-604-299