Photochemical Efficiencies of Diatom Symbionts in Hospite in Amphistegina Gibbosa (foraminifera) Across Seasons in the Florida Keys, Usa

2018 ◽  
Vol 48 (1) ◽  
pp. 4-16 ◽  
Author(s):  
Natasha Méndez-Ferrer ◽  
Pamela Hallock ◽  
David L. Jones
Keyword(s):  
Photochemical Efficiency ◽  
Florida Keys ◽  
Pulse Amplitude ◽  
Light Curves ◽  
Model Organisms ◽  
Initial Slope ◽  
Quantum Yields ◽  
Photosynthetic Parameters ◽  
Amphistegina Gibbosa ◽  
Rapid Light Curves

Abstract Benthic foraminiferal taxa that host algal endosymbionts can serve as model organisms in understanding photo-oxidative stress in environments where algal symbioses are prevalent. This study examined photochemical performance of the diatom symbionts within the foraminifer Amphistegina gibbosa. Data on bleaching prevalence and photochemical efficiency for photosystem II (PSII) were obtained from specimens collected at Tennessee Reef, Florida reef tract, USA, as close as logistically feasible to each equinox and solstice in 2012 and 2013. Specimens were collected at 6 m and 18 m depths, isolated, visually characterized, and assessed for maximum quantum yield of PSII using a pulse-amplitude modulated (PAM) fluorometer. Rapid-light curves (RLCs) were performed in the laboratory on specimens within a few hours of collection. Trials examined the effects of depth, sampling date, and degree of host bleaching. Consistent with field studies in the 1990s, proportions of A. gibbosa populations exhibiting visible loss of symbionts (i.e., “bleaching”) were lowest in December, with between-season and between-year differences in maxima. Maximum quantum yields ranged from 0.66–0.76. Significant differences between sampling dates were found at the 6 m site, with highest yields in winter and lowest in summer. At the 18 m site, maximum quantum yields differed both by sampling date and by degree of bleaching. Rapid light curves revealed that relative electron transport rates were highest in specimens exhibiting no visible symbiont loss; derived-photosynthetic parameters of α (initial slope of the RLC) and Ek (minimum saturating irradiance) did not differ significantly across different degrees of symbiont loss. Overall results indicate that even individuals exhibiting substantial symbiont loss retain some fully functional symbionts.

Exposure times in rapid light curves affect photosynthetic parameters in algae

2010 ◽  
Vol 93 (3) ◽  
pp. 185-194 ◽  
Author(s):  
Sven Ihnken ◽  
Anja Eggert ◽  
John Beardall
Keyword(s):  
Light Curves ◽  
Photosynthetic Parameters ◽  
Rapid Light Curves

scholarly journals A Novel Thin-Film Technique to Improve Accuracy of Fluorescence-Based Estimates for Periphytic Biofilms

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1464
Author(s):  
Leon Katona ◽  
Yvonne Vadeboncoeur ◽  
Christopher T. Nietch ◽  
Katie Hossler
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Light Attenuation ◽  
Pulse Amplitude ◽  
Light Signal ◽  
Photosynthetic Parameters ◽  
Pam Fluorometry ◽  
Attenuation Coefficients ◽  
Thin Film Technique ◽  
Relative Errors

Recent studies suggest that photophysiological parameters for intact substrates with depth (e.g., periphytic biofilms, microphytobenthos) are overestimated by pulse-amplitude modulated (PAM) fluorometry. This overestimation results from depth-integration effects, following the activation of deeper photosynthesizing layers by an attenuated light signal. To mitigate this error, we propose a novel slide-based thin-film technique in which fluorescence is measured on a vertically representative subsample of the biofilm, spread evenly on a microscope slide. We compared bias and precision for photosynthetic parameters estimated through conventional PAM fluorometry on intact biofilms and through our novel slide-based technique, both theoretically and empirically. Numerical simulations confirmed the consistent overestimation of key parameters for intact biofilms, with relative errors up to 145%, compared to, at most, 52% on thin films. Paired empirical observations likewise demonstrated that estimates based on intact biofilms were consistently higher (up to 248%, p<0.001) than estimates from thin films. Numerical simulation suggested greater precision with the slide-based technique for homogeneous biofilms, but potentially less precision for heterogeneous biofilms with improper subsampling. Our empirical comparison, however, demonstrated some improvement in precision with the slide-based technique (e.g., the coefficient of variation for the maximum electron transport rate was reduced 30%, p=0.009). We recommend the use of the slide-based technique, particularly for biofilms that are thick or have small light attenuation coefficients. Care should be taken, however, to obtain vertically representative subsamples of the biofilm for measurement.

scholarly journals Comparison of photosynthetic fluorescence characteristics of several submerged plants in Honghu Lake, China

2021 ◽  
Vol 49 (2) ◽  
pp. 12173
Author(s):  
Yuan-Qin ZHU ◽  
Bo-Han JING ◽  
Long-Yi YUAN
Keyword(s):  
Pulse Amplitude ◽  
Water Remediation ◽  
Quantum Yields ◽  
Limiting Factor ◽  
Pioneer Species ◽  
Submerged Plants ◽  
Honghu Lake ◽  
Fluorescence Characteristics ◽  
Water Restoration ◽  
Variation Trends

Submerged plants are the pioneer species of eutrophic water remediation, and they are important for maintaining the health of aquatic ecosystem, while light is the main limiting factor for the growth of submerged plants. In this study, we measured the maximal quantum yields of photosystemⅡ(Fv/Fm) and rapid light curves (RLCs) of five dominant submerged macrophytes in situ by using pulse-amplitude modulated fluorometer (Diving-PAM). Results revealed that P. crispus L. and M. verticillatum L. had the highest Fv/Fm value, all species’ Fv/Fm are less than 0.8. In addition, the variation trends of Fv'/Fm' and Fv/Fm were same. All species showed statistically significant differences in α, while P. crispus L. and M. verticillatum L. showed the highest α value in the five species. And the variation trends of rETRm and Ek were basically the same. It indicated that P. crispus L. and M. verticillatum L., both of which had high photosynthetic efficiency, had excellent ability to withstand hard light. Compared five species, P. crispus L. and M. verticillatum L. had resistance capacity to hard light as well as faster photosynthetic rate, and V. natans (Lour.) Hara had higher resistance capacity to low light. Thus, when submerged plants are used for water restoration, V. natans (Lour.) Hara could be regarded as a pioneer species in eutrophication water restoration. P. crispus L. and M. verticillatum L. will have better effects when used in shallow water areas.

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.

Quantitative Determination of Photokinetic Parameters for Reversible Photoisomerizations in Light Scattering Adsorbent-Adsorbates

2000 ◽  
Vol 214 (2) ◽  
Author(s):  
R. Gade ◽  
Th. Porada
Keyword(s):  
Approximate Solution ◽  
Light Scattering ◽  
Quantum Yield ◽  
Present Method ◽  
Irradiation Time ◽  
Initial Slope ◽  
Quantum Yields ◽  
Absorption Coefficients ◽  
Actinic Light

Based on an approximate solution of the differential equations describing the rate of a reversible photoisomerization and the attenuation of the actinic light in a powdered adsorbent-adsorbate a method is presented permitting us to predict the irradiation time dependence of the sample reflectance and to determine both the quantum yields of the partial reactions and the absorption coefficients of the reactant and the product from the reflectance-time-curves measured at two different wavelengths. The present method, thus, is an improved version of the peviously reported procedure [1] which enables the quantum yield of a simple photoreaction to be calculated from the initial slope of the R(

scholarly journals NaCl improves reproduction by enhancing starch accumulation in the ovules of the euhalophyte Suaeda salsa

2020 ◽  
Author(s):  
Jianrong Guo ◽  
Ming Du ◽  
Chaoxia Lu ◽  
Baoshan Wang
Keyword(s):  
Photosynthetic Efficiency ◽  
Photochemical Efficiency ◽  
Sucrose Phosphate Synthase ◽  
Suaeda Salsa ◽  
Starch Accumulation ◽  
Photosynthetic Parameters ◽  
Carbon Utilization ◽  
Genes Encoding ◽  
Sucrose Phosphate

Abstract Background: Halophytes show optimal reproduction under high-salinity conditions. However, the role of NaCl in reproduction and its possible mechanisms in the euhalophyte Suaeda salsa remain to be elucidated. Results: We performed transcript profiling of S. salsa flowers and measured starch accumulation in ovules, sugar contents in flowers, and photosynthetic parameters in the leaves of plants supplied with 0 and 200 mM NaCl. Starch accumulation in ovules, sugar contents in flowers and ovules, and net photosynthetic rate and photochemical efficiency in leaves were significantly higher in NaCl-treated plants vs. the control. We identified 14,348 differentially expressed genes in flowers of NaCl-treated vs. control plants. Many of these genes were predicted to be associated with photosynthesis, carbon utilization, and sugar and starch metabolism. These genes are crucial for maintaining photosystem structure, regulating electron transport, and improving photosynthetic efficiency in NaCl-treated plants. In addition, genes encoding fructokinase and sucrose phosphate synthase were upregulated in flowers of NaCl-treated plants. Conclusions: The higher starch and sugar contents in the ovules and flowers of S. salsa in response to NaCl treatment are likely due to the upregulation of genes involved in photosynthesis and carbohydrate metabolism, which increase photosynthetic efficiency and accumulation of photosynthetic products under these conditions.

scholarly journals A procedure for maize genotypes discrimination to drought by chlorophyll fluorescence imaging rapid light curves

Plant Methods ◽  
2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Carlos Antônio Ferreira de Sousa ◽  
Dayane Silva de Paiva ◽  
Raphael Augusto das Chagas Noqueli Casari ◽  
Nelson Geraldo de Oliveira ◽  
Hugo Bruno Correa Molinari ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Fluorescence Imaging ◽  
Light Curves ◽  
Chlorophyll Fluorescence Imaging ◽  
Maize Genotypes ◽  
Rapid Light Curves

scholarly journals Relationship between photosynthetic parameters and different proxies of phytoplankton biomass in the subtropical ocean

2007 ◽  
Vol 4 (5) ◽  
pp. 853-868 ◽  
Author(s):  
Y. Huot ◽  
M. Babin ◽  
F. Bruyant ◽  
C. Grob ◽  
M. S. Twardowski ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Initial Slope ◽  
Photosynthetic Parameters ◽  
Backscattering Coefficient ◽  
South Pacific Ocean ◽  
Almost All ◽  
Best Estimator

Abstract. Probably because it is a readily available ocean color product, almost all models of primary productivity use chlorophyll as their index of phytoplankton biomass. As other variables become more readily available, both from remote sensing and in situ autonomous platforms, we should ask if other indices of biomass might be preferable. Herein, we compare the accuracy of different proxies of phytoplankton biomass for estimating the maximum photosynthetic rate (Pmax) and the initial slope of the production versus irradiance (P vs. E) curve (α). The proxies compared are: the total chlorophyll a concentration (Tchla, the sum of chlorophyll a and divinyl chlorophyll), the phytoplankton absorption coefficient, the phytoplankton photosynthetic absorption coefficient, the active fluorescence in situ, the particulate scattering coefficient at 650 nm (bp(650)), and the particulate backscattering coefficient at 650 nm (bbp(650)). All of the data (about 170 P vs. E curves) were collected in the South Pacific Ocean. We find that when only the phytoplanktonic biomass proxies are available, bp(650) and Tchla are respectively the best estimators of Pmax and α. When additional variables are available, such as the depth of sampling, the irradiance at depth, or the temperature, Tchla is the best estimator of both Pmax and α.

scholarly journals Root Abscisic Acid Contributes to Defending Photoinibition in Jerusalem Artichoke (Helianthus tuberosus L.) under Salt Stress

2018 ◽  
Vol 19 (12) ◽  
pp. 3934 ◽  
Author(s):  
Kun Yan ◽  
Tiantian Bian ◽  
Wenjun He ◽  
Guangxuan Han ◽  
Mengxue Lv ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Salt Stress ◽  
Photochemical Efficiency ◽  
Jerusalem Artichoke ◽  
Photosynthetic Parameters ◽  
Synthesis Inhibitor ◽  
Potted Plants ◽  
Photochemical Efficiency Of Psii ◽  
Electron Donation ◽  
Aba Content

The aim of the study was to examine the role of root abscisic acid (ABA) in protecting photosystems and photosynthesis in Jerusalem artichoke against salt stress. Potted plants were pretreated by a specific ABA synthesis inhibitor sodium tungstate and then subjected to salt stress (150 mM NaCl). Tungstate did not directly affect root ABA content and photosynthetic parameters, whereas it inhibited root ABA accumulation and induced a greater decrease in photosynthetic rate under salt stress. The maximal photochemical efficiency of PSII (Fv/Fm) significantly declined in tungstate-pretreated plants under salt stress, suggesting photosystem II (PSII) photoinhibition appeared. PSII photoinhibition did not prevent PSI photoinhibition by restricting electron donation, as the maximal photochemical efficiency of PSI (ΔMR/MR0) was lowered. In line with photoinhibition, elevated H2O2 concentration and lipid peroxidation corroborated salt-induced oxidative stress in tungstate-pretreated plants. Less decrease in ΔMR/MR0 and Fv/Fm indicated that PSII and PSI in non-pretreated plants could maintain better performance than tungstate-pretreated plants under salt stress. Consistently, greater reduction in PSII and PSI reaction center protein abundance confirmed the elevated vulnerability of photosystems to salt stress in tungstate-pretreated plants. Overall, the root ABA signal participated in defending the photosystem’s photoinhibition and protecting photosynthesis in Jerusalem artichoke under salt stress.

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