scholarly journals Chlorophyll fluorescence: How the quality of information about PAM instrument parameters may affect our research

2021 ◽  
Author(s):  
Tim Nies ◽  
Yuxi Niu ◽  
Oliver Ebenhöh ◽  
Shizue Matsubara ◽  
Anna Matuszyńska
Keyword(s):  
Data Science ◽  
Measurement Techniques ◽  
Mathematical Formulation ◽  
Pulse Amplitude ◽  
Data Interpretation ◽  
Photochemical Quenching ◽  
Non Photochemical Quenching ◽  
Underlying Processes ◽  
Kinetics Of

Chlorophyll a fluorescence is a powerful indicator of photosynthetic energy conversion in plants and photosynthetic microorganisms. One of the most widely used measurement techniques is Pulse Amplitude Modulation (PAM) fluorometry. Unfortunately, parameter settings of PAM instruments are often not completely described in scientific articles although their variations, however small these may seem, can influence measurements. We show the effects of parameter settings on PAM measurements. We first simulated fluorescence signals using a previously published computational model of photosynthesis. Then, we validated our findings experimentally. Our analysis demonstrates how the kinetics of non-photochemical quenching (NPQ) induction and relaxation are affected by different settings of PAM instrument parameters. Neglecting these parameters may mislead data interpretation and derived hypotheses, hamper independent validation of the results, and cause problems for mathematical formulation of underlying processes. Given the uncertainties inflicted by this neglect, we urge PAM users to provide detailed documentation of measurement protocols. Moreover, to ensure accessibility to the required information, we advocate minimum information standards that can serve both experimental and computational biologists in our efforts to advance system-wide understanding of biological processes. Such specification will enable launching a standardized database for plant and data science communities.

scholarly journals Relation of Photochemical Reflectance Indices Based on Different Wavelengths to the Parameters of Light Reactions in Photosystems I and II in Pea Plants

2020 ◽  
Vol 12 (8) ◽  
pp. 1312
Author(s):  
Ekaterina Sukhova ◽  
Vladimir Sukhov
Keyword(s):  
Remote Sensing ◽  
Pulse Amplitude ◽  
Ecological Monitoring ◽  
Photochemical Quenching ◽  
Photosynthetic Parameters ◽  
Pam Fluorometer ◽  
Physiological Processes ◽  
Non Photochemical Quenching ◽  
Induced Changes ◽  
Reflectance Indices

Measurement and analysis of the numerous reflectance indices of plants is an effective approach for the remote sensing of plant physiological processes in agriculture and ecological monitoring. A photochemical reflectance index (PRI) plays an important role in this kind of remote sensing because it can be related to early changes in photosynthetic processes under the action of stressors (excess light, changes in temperature, drought, etc.). In particular, we previously showed that light-induced changes in PRIs could be strongly related to the energy-dependent component of the non-photochemical quenching in photosystem II. The aim of the present work was to undertake comparative analysis of the efficiency of using light-induced changes in PRIs (ΔPRIs) based on different wavelengths for the estimation of the parameters of photosynthetic light reactions (including the parameters of photosystem I). Pea plants were used in the investigation; the photosynthetic parameters were measured using the pulse-amplitude-modulated (PAM) fluorometer Dual-PAM-100 and the intensities of the reflected light were measured using the spectrometer S100. The ΔPRIs were calculated as ΔPRI(band,570), where the band was 531 nm for the typical PRI and 515, 525, 535, 545, or 555 nm for modified PRIs; 570 nm was the reference wavelength for all PRIs. There were several important results: (1) ∆PRI(525,570), ∆PRI(531,570), ∆PRI(535,570), and ∆PRI(545,570) could be used for estimation of most of the photosynthetic parameters under light only or under dark only conditions. (2) The combination of dark and light conditions decreased the efficiency of ∆PRIs for the estimation of the photosynthetic parameters; ∆PRI(535,570) and ∆PRI(545,570) had maximal efficiency under these conditions. (3) ∆PRI(515,570) and ∆PRI(525,570) mainly included the slow-relaxing component of PRI; in contrast, ∆PRI(531,570), ∆PRI(535,570), ∆PRI(545,570), and ∆PRI(555,570) mainly included the fast-relaxing component of PRI. These components were probably caused by different mechanisms.

Using Sun-induced fluorescence and Carbonyl Sulfide flux to assess the response to seasonal heatwave in a citrus orchard

2020 ◽  
Author(s):  
Amnon Cochavi ◽  
Madi Amer ◽  
Rafael Stern ◽  
Dan Yakir
Keyword(s):  
Heat Stress ◽  
Carbonyl Sulfide ◽  
Carbon Assimilation ◽  
Net Ecosystem Exchange ◽  
Pulse Amplitude ◽  
Full Scale ◽  
Photochemical Quenching ◽  
Air Temperatures ◽  
Net Assimilation ◽  
Non Photochemical Quenching

<p>Springtime heatwaves are common phenomena in the Mediterranean region, named ‘Sharav’ or ‘Hamsin’. During these heatwaves, air temperatures (Ta) and vapor pressure demand (VPD) increase rapidly over 3-5 days, followed by a dramatic drop of at least 5℃ in Ta and 1 kPa in VPD back to the pre-event values.</p><p>Here, we used our mobile lab in an irrigated lemon orchard in Rehovot, Israel to carry out eddy covariance (EC) flux measurements of net ecosystem exchange of CO<sub>2</sub> (NEE), water vapor, and carbonyl sulfide (COS), as well as canopy Sun-induced fluorescence (SIF) together with other spectral indices (NDVI, PRI, NIRv). This was supplemented with leaf-scale measurements of Pulse Amplitude modulated (PAM). Five heatwave events were detected during a two-months measurement campaign. Two other events were defined as intermediate days, with VPD values higher than normal but lower than in the full-scale heatwaves.</p><p>During both the heatwave and intermediate days, the COS fluxes (Fcos), far-red SIF, and electron transport rate (ETR), decreased during midday to the same level, compared to the control days. In contrast, NEE responded differentially between the heatwave and intermediate days, with midday values of -5.9±0.9, -3.7±0.7 and -0.69±0.62 µmol m<sup>-2</sup>s<sup>-1</sup> CO<sub>2</sub>, in the control, intermediate and heatwave days, respectively. No differences were detected in both NDVI and NIRv values. The PRI index, related to energy transfer through the non-photochemical quenching (NPQ) pathway, showed a similar pattern to that of NEE. The recovery of the ecosystem from the heatwave events was rapid and occurred within a day after the end of the events.</p><p>The results indicate a link between the far-red SIF and the ETR in the response to the heatwaves. Moreover, the reduction in far-red SIF was negatively associated with the increase in NPQ, which was reflected in both the spectral (PRI) and the PAM (NPQ value) measurements. The observed decrease in Fcos is expected to reflect a decrease in stomatal conductance to a similar extent in the heatwave and intermediate days. However, the lower rate of CO<sub>2</sub> assimilation in the full-scale heat wave days suggests that additional factors further decreased its rates beyond that limited by conductance. This can be related to the increased effect of the heat stress on other energy-demanding pathways (e.g. photorespiratory, isoprene production) that can suppress net assimilation in these days.</p><p>This work demonstrated that the relation between carbon assimilation and far-red SIF can be complex, and that combining SIF and COS measurements can help partition the effects of heat stress on conductance and other physiological effects.</p>

scholarly journals Mediator-Microorganism Interaction in Microbial Solar Cell: a Fluo-Electrochemical Insight

2020 ◽  
Author(s):  
Léna Beauzamy ◽  
Jérôme Delacotte ◽  
Benjamin Bailleul ◽  
Kenya Tanaka ◽  
Shuji Nakanishi ◽  
...  
Keyword(s):  
Pulse Amplitude ◽  
Simultaneous Recording ◽  
Electricity Production ◽  
Photochemical Quenching ◽  
Experimental Conditions ◽  
Promising Alternative ◽  
Photochemical Yield ◽  
Set Up ◽  
Solar Electricity ◽  
Non Photochemical Quenching

ABSTRACTMicrobial solar cells that mainly rely on the use of photosynthesic organisms are a promising alternative to photovoltaics for solar electricity production. In that way, we propose a new approach involving electrochemistry and fluorescence techniques. The coupled set-up Electro-Pulse-Amplitude-Modulation (“e-PAM”) enables the simultaneous recording of the produced photocurrent and fluorescence signals from the photosynthetic chain. This methodology was validated with a suspension of green alga Chlamydomonas reinhardtii in interaction with an exogenous redox mediatior (2,6-dichlorobenzoquinone; DCBQ). The balance between photosynthetic chain events (PSII photochemical yield, quenching) and the extracted electricity can be monitored overtime. More particularly, the non photochemical quenching induced by DCBQ mirrors the photocurrent. This set-up thus helps to distinguish the electron harvesting from some side effects due to quinones in real time. It therefore paves the way for future analyses devoted to the choice of the experimental conditions (redox mediator, photosynthetic organisms…) to find the best electron extraction.

The xanthophyll cycle pool size controls the kinetics of non-photochemical quenching inArabidopsis thaliana

FEBS Letters ◽  
2007 ◽  
Vol 582 (2) ◽  
pp. 262-266 ◽  
Author(s):  
Matthew P. Johnson ◽  
Paul A. Davison ◽  
Alexander V. Ruban ◽  
Peter Horton
Keyword(s):  
Xanthophyll Cycle ◽  
Pool Size ◽  
Photochemical Quenching ◽  
Non Photochemical Quenching ◽  
Kinetics Of

scholarly journals Short-term effects of heavy metal and temperature stresses on the photophysiology of Symbiodinium isolated from the coral Fungia repanda

Ocean Life ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 11-20 ◽  
Author(s):  
MANJULA D. GHOORA ◽  
SIVAJYODEE S. PILLY ◽  
PRAMOD KUMAR CHUMUN ◽  
SHOBHA JAWAHEER ◽  
RANJEET BHAGOOLI
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Photosynthetic Capacity ◽  
Pulse Amplitude ◽  
Photochemical Quenching ◽  
Short Term ◽  
Temperature Stresses ◽  
Clade C ◽  
Non Photochemical Quenching ◽  
Short Term Effects

Ghoora MD, Pilly SS, Chumun PK, Jawaheer S, Bhagooli R. 2017. Short-term effects of heavy metal and temperature stresses on the photo-physiology of Symbiodinium isolated from the coral Fungia repanda. Ocean Life 1: 11-20. This study aimed to investigate the effects of the heavy metals, copper, zinc and lead, on the photo-physiology of the symbiotic dinoflagellate Symbiodinium isolated from the coral Fungia repanda. Freshly isolated Symbiodinium found to belong to clade C were exposed to different concentrations of the three heavy metals for 3-hour and 18-hour treatments at 28°C and 32°C. The Pulse Amplitude Modulated (PAM) fluorometry technique was used to determine the maximum quantum yield (Fv/Fm), relative maximum electron transport rate (rETRmax) and maximum non-photochemical quenching (NPQmax) of the photosystem II (PSII). An increase in non-photochemical quenching accompanied by a decrease in photosynthetic capacity was noted for copper at a concentration of 50 µg/L for both temperatures. The Fv/Fm was not significantly affected by the Zn treatments. However, at 28 °C, isolates treated with 100 µg/L Zn for 18 hours showed an increase in non-photochemical quenching accompanied by a decrease in photosynthetic capacity. Pb had the most profound effect on all of the isolates. The Fv/Fm significantly decreased and an increase in NPQmax was noted. The decrease of rETRmax and increase in NPQmax for the heavy metal bioassays under 32 °C were more significant than at 28 °C. This study suggests that Cu (≥50 µg/L), Zn (≥ 100 µg/L) and Pb decrease the photosynthetic capacity of the Symbiodinium isolates from F. repanda especially more so with increasing temperatures.

scholarly journals A four state parametric model for the kinetics of the non-photochemical quenching in Photosystem II

2017 ◽  
Vol 1858 (10) ◽  
pp. 854-864 ◽  
Author(s):  
Joris J. Snellenburg ◽  
Matthew P. Johnson ◽  
Alexander V. Ruban ◽  
Rienk van Grondelle ◽  
Ivo H.M. van Stokkum
Keyword(s):  
Photosystem Ii ◽  
Parametric Model ◽  
Photochemical Quenching ◽  
Non Photochemical Quenching ◽  
Kinetics Of

scholarly journals Determination of Sorption Properties of Heavy Metals in Various Biosorbents

2018 ◽  
Vol 25 (2) ◽  
pp. 201-216 ◽  
Author(s):  
Andrzej Kłos
Keyword(s):  
Data Interpretation ◽  
Copper Cation ◽  
Reaction Model ◽  
Static System ◽  
Heavy Metal Sorption ◽  
Pseudo Second Order ◽  
High Degree ◽  
Kinetics Of

Abstract Various techniques of determination of properties of physicochemical processes of heavy metal sorption in biosorbents were analysed. The methods of preparing and storing samples, conditions of experiment performance, as well as the methods of data interpretation were discussed. Two procedures of study were analysed: (1) in the static system of biosorbent-solution contact and (2) in the system of dynamic flow of solution. Copper cation sorption was studied. The effect of consecutive stages of the study on the quality of final results was shown. A high degree of uncertainty of the sorption capacity assessment was reported, which was dependent on the manner of conducting the study. The application of the pseudo-second order reaction model was substantiated to describe kinetics of cation-exchange sorption and the model of Langmuir isotherm to describe equilibria. The study conducted reveals that in order to perform comparative analyses, it is necessary to establish a joint concept of conducting studies and the interpretation of results.

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