[Coral-List] PAM Question

[shashank Keshavmurthy]

Dear Mr. Harkins and listers
I am sorry if I did not express myself properly.
I had no intention to undermine the usage of DIVING PAM. I just wanted to say that in instances where one cannot dark adapt their samples, DIVING PAM is a powerful instrument to get the readings even in Light adapted samples.  This is especially when one is using it in the field.
Still researchers feel the need of dark adapting their samples in the field or in laboratory experiments, which is a necessity or just following previous examples...again it all depends on what one is trying to do...

Even the publications that I mentioned, eventually use dark adaptation of their samples to see the difference.

I am just trying to explore the possibilities of overcoming this trend and still get a meaningful result out of PAM readings without dark adaptation.

As Mr. Harkins explains there are other alternatives which can be adapted.

Thanks again for all the help
shashank
 ===============================================================
Whether our efforts are, or not, favored by life, let us be able to say, when we come near the great goal,I have done what I could - Louis Pasteur


Role of Infinitely Small in Nature is Infinitely Large - Louis Pasteur
===============================================================
Keshavmurthy Shashank
Post Doctoral Research Fellow, Dr. Chen's lab
Biodiversity Research Center, Academia Sinica (RCBAS)
128 Academia Road Sec. 2, Nankang 
Taipei 115 Taiwan, ROC.
My WebPage: http://web.mac.com/coralresearch/iWeb/shashank/Welcome.html
Lab WebPage: http://coral.biodiv.tw/Default.aspx
Alt. E-mail: shashank at gate.sinica.edu.tw, coralresearch at mac.com



----- Original Message ----
From: walzusa1 <mail at walz-usa.com>
To: coral-list at coral.aoml.noaa.gov
Sent: Thu, November 5, 2009 1:37:50 AM
Subject: [Coral-List] PAM Question

Dear Dr. Keshavmurthy,

Regarding your questions about the Diving-PAM... I think you are 
taking the German translation into English too literally. While the 
Diving-PAM is optimized for taking the photosynthetic Yield (Genty 
parameter) this is not the instruments sole function or sole 
speciality. For instance, the Light Curve, an automated test that 
subjects the sample to different light intensities and the Induction 
Curve, are quite useful in interpreting physiological status and 
detecting/studying the subtle effects of environmental stress.

The passage you site in the manual is to underscore the convenience 
of the set-up for the user not to imply that Diving-PAM is only 
useful for single point Yield tests. I can certainly see how it could 
be taken so literally though so we'll have to change it in the new 
manuals. We stress the convenience of this parameter as diving is a 
time sensitive activity and until the recent developments of our 
Underwater Monitoring-PAM, which is an automated, continuos 
photosynthesis measuring system, getting a lot of measurements fast 
was of utmost  import and the only way to do it.

On another point, there is a PAR sensor with the Diving-PAM that 
helps you make sense of the fluorescence readings. As you pointed 
out, the light intensity from site to site can differ greatly and if 
you are not measuring light intensity along with fluorescence, it can 
be difficult to determine the organisms photochemical efficiency.

You do not always have to dark adapt a sample. Tests like the Yield, 
ACT+Yield, which subject the sample to a fixed amount of light for a 
defined period of time, the Light Curve and Induction Curve can be 
used instead of or to complement Fv/Fm or traditional Dark Adapted 
tests. I think you may be hoping to find that one parameter that is 
definitive and unfortunately, that is both the good thing and bad 
thing about PAM measurements. All these different tests and 
parameters help you pinpoint what type of stress or where along the 
photochemical pathway inhibition is occurring. However, one stress 
might show up in Test A or parameter A while another type of stress 
might show up in Parameter B.

I invite you to visit our web site for a list of publications and an 
overview of PAM fluorometry which provides greater detail. Please 
feel free to contact me directly with any further questions. I will 
be more than happy to go over your experiment goals and help you 
figure out how best to utilize the PAM to get the information you need.

Best regards,
Dan Harkins
Walz-USA

tel: 978-433-2757
mail at walz-usa.com
www.walz.com





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