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Detection of rapid induction kinetics with a new type of high-frequency modulated chlorophyll fluorometer

Detection of rapid induction kinetics with a new type of high-frequency modulated chlorophyll... A newly developed modulation fluorometer is described which operates with 1 μsec light pulses from a light-emitting diode (LED) at 100 KHz. Special amplification circuits assure a highly selective recording of pulse fluorescence signals against a vast background of non-modulated light. The system tolerates ratios of up to 1:107 between measuring light and actinic light. Thus it is possible to measure the “dark fluorescence yield” and record the kinetics of light-induced changes. A high time resolution allows the recording of the rapid relaxation kinetic following a saturating single turnover flash. Examples of system performance are given. It is shown that following a flash the reoxidation kinetics of photosystem II acceptors are slowed down not only by the inhibitor DCMU, but by a number of other treatments as well. From a light intensity dependency of the induction kinetics the existence of two saturated intermediate levels (I1 and I2) is apparent, which indicates the removal of three distinct types of fluorescence quenching in the overall fluorescence rise from F0 to Fmax. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Photosynthesis Research Springer Journals

Detection of rapid induction kinetics with a new type of high-frequency modulated chlorophyll fluorometer

Photosynthesis Research , Volume 9 (2) – Apr 20, 2004

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References (36)

Publisher
Springer Journals
Copyright
Copyright
Subject
Life Sciences; Plant Sciences; Plant Physiology; Biochemistry, general; Plant Genetics and Genomics
ISSN
0166-8595
eISSN
1573-5079
DOI
10.1007/BF00029749
Publisher site
See Article on Publisher Site

Abstract

A newly developed modulation fluorometer is described which operates with 1 μsec light pulses from a light-emitting diode (LED) at 100 KHz. Special amplification circuits assure a highly selective recording of pulse fluorescence signals against a vast background of non-modulated light. The system tolerates ratios of up to 1:107 between measuring light and actinic light. Thus it is possible to measure the “dark fluorescence yield” and record the kinetics of light-induced changes. A high time resolution allows the recording of the rapid relaxation kinetic following a saturating single turnover flash. Examples of system performance are given. It is shown that following a flash the reoxidation kinetics of photosystem II acceptors are slowed down not only by the inhibitor DCMU, but by a number of other treatments as well. From a light intensity dependency of the induction kinetics the existence of two saturated intermediate levels (I1 and I2) is apparent, which indicates the removal of three distinct types of fluorescence quenching in the overall fluorescence rise from F0 to Fmax.

Journal

Photosynthesis ResearchSpringer Journals

Published: Apr 20, 2004

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