David GROSS wrote in message <354EC10B.4240 at wanadoo.fr>...
>Hello,
>> I'm trying to measure fluorescence and thermoluminescence on
>different moss species. The first results gave me strange trends :
>>- for fluorescence, I've got a variable fluorescence for one specie
>(pleurozium schreberi), but not for the other specie (scleropodium
>purum). Can you explain this ?
>>I guess it's because the PS2 doesn't give electron to QA...
>
I think it is much more likely that your basal fluorescence (Fo) is
dominated
by phycobilisome fluorescence and against this background the small Fv
is hardly
noticeable.
>- for the thermoluminescence, both species present small
>thermoluminescence for small temperatures, but it increases a lot for
70
>to 100 degree (C). Again, can you explain that fact ?
>>Perhaps this is a stress reaction ?
We have one some work on the 70 degrees thermoluminescence. It is a
chemiluminescence
signal (i.e. no need to preilluminate) and we concluded that it is
indeed related to stress, particularly interaction between chlorophyll
and (per)oxidation products in the membrane. The paper is coming
out quite soon in Physiol. Plantarum. Meanwhile, you can look over the
abstract at
http://www.agri.huji.ac.il/~marder/research/pisa1997.abs
You might also want to take a look at papers by:-
Merzlyak et al (1992) J. Plant Physiol. 139: 629-631.
Hideg and Vass (1993) Photochem. Photobiol. 58: 280-283.
Jonathan B. Marder <MARDER at agri.huji.ac.il>
Department of Agricultural Botany, The Hebrew University of Jerusalem
Faculty of Agriculture, P.O.Box 12, Rehovot 76100, ISRAEL
Phone: +972 8 9481918 Fax: +972 8 9467763
Web page: http://www.agri.huji.ac.il/~marder
