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Ingwani T, Chaukura N, Mamba BB, Nkambule TTI, Gilmore AM. Detection and Quantification of Bisphenol A in Surface Water Using Absorbance-Transmittance and Fluorescence Excitation-Emission Matrices (A-TEEM) Coupled with Multiway Techniques. Molecules 2023; 28:7048. [PMID: 37894527 PMCID: PMC10609475 DOI: 10.3390/molecules28207048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/14/2023] [Accepted: 10/05/2023] [Indexed: 10/29/2023] Open
Abstract
In the present protocol, we determined the presence and concentrations of bisphenol A (BPA) spiked in surface water samples using EEM fluorescence spectroscopy in conjunction with modelling using partial least squares (PLS) and parallel factor (PARAFAC). PARAFAC modelling of the EEM fluorescence data obtained from surface water samples contaminated with BPA unraveled four fluorophores including BPA. The best outcomes were obtained for BPA concentration (R2 = 0.996; standard deviation to prediction error's root mean square ratio (RPD) = 3.41; and a Pearson's r value of 0.998). With these values of R2 and Pearson's r, the PLS model showed a strong correlation between the predicted and measured BPA concentrations. The detection and quantification limits of the method were 3.512 and 11.708 micro molar (µM), respectively. In conclusion, BPA can be precisely detected and its concentration in surface water predicted using the PARAFAC and PLS models developed in this study and fluorescence EEM data collected from BPA-contaminated water. It is necessary to spatially relate surface water contamination data with other datasets in order to connect drinking water quality issues with health, environmental restoration, and environmental justice concerns.
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Affiliation(s)
- Thomas Ingwani
- Institute for Nanotechnology and Water Sustainability, College of Engineering, Science and Technology, University of South Africa, Johannesburg 1709, South Africa; (T.I.); (B.B.M.); (A.M.G.)
| | - Nhamo Chaukura
- Department of Physical and Earth Sciences, Sol Plaatje University, Kimberley 8300, South Africa;
| | - Bhekie B. Mamba
- Institute for Nanotechnology and Water Sustainability, College of Engineering, Science and Technology, University of South Africa, Johannesburg 1709, South Africa; (T.I.); (B.B.M.); (A.M.G.)
| | - Thabo T. I. Nkambule
- Institute for Nanotechnology and Water Sustainability, College of Engineering, Science and Technology, University of South Africa, Johannesburg 1709, South Africa; (T.I.); (B.B.M.); (A.M.G.)
| | - Adam M. Gilmore
- Institute for Nanotechnology and Water Sustainability, College of Engineering, Science and Technology, University of South Africa, Johannesburg 1709, South Africa; (T.I.); (B.B.M.); (A.M.G.)
- Horiba Instruments Incorporated Inc., Piscataway, NJ 08854, USA
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Gilmore AM, Elhendawy MA, Radwan MM, Kidder LH, Wanas AS, Godfrey M, Hildreth JB, Robinson AE, ElSohly MA. Absorbance-Transmittance Excitation Emission Matrix Method for Quantification of Major Cannabinoids and Corresponding Acids: A Rapid Alternative to Chromatography for Rapid Chemotype Discrimination of Cannabis sativa Varieties. Cannabis Cannabinoid Res 2023; 8:911-922. [PMID: 35486823 PMCID: PMC10589469 DOI: 10.1089/can.2021.0165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background: Phytocannabinoids naturally occur in the cannabis plant (Cannabis sativa), and Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) predominate. There is a need for rapid inexpensive methods to quantify total THC (for statutory definition) and THC-CBD ratio (for classification into three chemotypes). This study explores the capabilities of a spectroscopic technique that combines ultraviolet-visible and fluorescence, absorbance-transmittance excitation emission matrix (A-TEEM). Methods: The A-TEEM technique classifies 49 dry flower extracts into three C. sativa chemotypes, and quantifies the total THC-CBD ratio, using validated gas chromatography (GC)-flame ionization (FID) and High-Performance Liquid Chromatography (HPLC) methods for reference. Multivariate methods used are principal components analysis for a chemotype classification, extreme gradient boost (XGB) discriminant analysis (DA) to classify unknown samples by chemotype, and XGB regression to quantify total THC and CBD content using GC-FID and HPLC data on the same samples. Results: The A-TEEM technique provides robust classification of C. sativa samples, predicting chemotype classification, defined by THC-CBD content, of unknown samples with 100% accuracy. In addition, A-TEEM can quantify total THC and CBD levels relevant to statutory determination, with limit of quantifications (LOQs) of 0.061% (THC) and 0.059% (CBD), and high cross-validation (>0.99) and prediction (>0.99), using a GC-FID method for reference data; and LOQs of 0.026% (THC) and 0.080% (CBD) with high cross-validation (>0.98) and prediction (>0.98), using an HPLC method for reference data. A-TEEM is highly predictive in separately quantifying acid and neutral forms of THC and CBD with HPLC reference data. Conclusions: The A-TEEM technique provides a sensitive method for the qualitative and quantitative characterization of the major cannabinoids in solution, with LOQs comparable with GC-FID and HPLC, and high values of cross-validation and prediction. As a spectroscopic technique, it is rapid, with data acquisition <45 sec per measurement; sample preparation is simple, requiring only solvent extraction. A-TEEM has the sensitivity to resolve and quantify cannabinoids in solution based on their unique spectral characteristics. Discrimination of legal and illegal chemotypes can be rapidly verified using XGB DA, and quantitation of statutory levels of total THC and total CBD comparable with GC-FID and HPLC can be obtained using XBD regression.
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Affiliation(s)
| | - Mostafa A. Elhendawy
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, USA
- Department of Agriculture Chemistry, Faculty of Agriculture, Damietta University, Damietta, Egypt
| | - Mohamed M. Radwan
- National Center for Natural Products Research, University of Mississippi, University, Mississippi, USA
| | | | - Amira S. Wanas
- National Center for Natural Products Research, University of Mississippi, University, Mississippi, USA
- Department of Pharmacognosy, Faculty of Pharmacy, Minia University, Minia, Egypt
| | - Murrell Godfrey
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi, USA
| | | | | | - Mahmoud A. ElSohly
- National Center for Natural Products Research, University of Mississippi, University, Mississippi, USA
- Department of Pharmaceutics and Drug Delivery, University of Mississippi, University, Mississippi, USA
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Armstrong CEJ, Gilmore AM, Boss PK, Pagay V, Jeffery DW. Corrigendum to "Machine learning for classifying and predicting grape maturity indices using absorbance and fluorescence spectra" [Food Chemistry 403 (2023) 134321]. Food Chem 2023; 406:135055. [PMID: 36496301 DOI: 10.1016/j.foodchem.2022.135055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Claire E J Armstrong
- Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia; School of Agriculture, Food and Wine, and Waite Research Institute, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia
| | - Adam M Gilmore
- HORIBA Instruments Inc., 20 Knightsbridge Road, Piscataway, NJ 08854, United States
| | - Paul K Boss
- Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia; CSIRO Agriculture and Food, Locked Bag 2, Glen Osmond, SA 5064, Australia
| | - Vinay Pagay
- Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia; School of Agriculture, Food and Wine, and Waite Research Institute, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia
| | - David W Jeffery
- Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia; School of Agriculture, Food and Wine, and Waite Research Institute, The University of Adelaide, PMB 1, Glen Osmond, South Australia 5064, Australia.
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Armstrong CE, Gilmore AM, Boss PK, Pagay V, Jeffery DW. Machine learning for classifying and predicting grape maturity indices using absorbance and fluorescence spectra. Food Chem 2023; 403:134321. [DOI: 10.1016/j.foodchem.2022.134321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 09/15/2022] [Accepted: 09/15/2022] [Indexed: 11/16/2022]
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Ranaweera RK, Bastian SE, Gilmore AM, Capone DL, Jeffery DW. Absorbance-transmission and fluorescence excitation-emission matrix (A-TEEM) with multi-block data analysis and machine learning for accurate intraregional classification of Barossa Shiraz wine. Food Control 2022. [DOI: 10.1016/j.foodcont.2022.109335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Ranaweera RKR, Gilmore AM, Capone DL, Bastian SEP, Jeffery DW. Spectrofluorometric analysis combined with machine learning for geographical and varietal authentication, and prediction of phenolic compound concentrations in red wine. Food Chem 2021; 361:130149. [PMID: 34082385 DOI: 10.1016/j.foodchem.2021.130149] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/21/2021] [Accepted: 05/15/2021] [Indexed: 12/13/2022]
Abstract
Fluorescence spectroscopy is rapid, straightforward, selective, and sensitive, and can provide the molecular fingerprint of a sample based on the presence of various fluorophores. In conjunction with chemometrics, fluorescence techniques have been applied to the analysis and classification of an array of products of agricultural origin. Recognising that fluorescence spectroscopy offered a promising method for wine authentication, this study investigated the unique use of an absorbance-transmission and fluorescence excitation emission matrix (A-TEEM) technique for classification of red wines with respect to variety and geographical origin. Multi-block data analysis of A-TEEM data with extreme gradient boosting discriminant analysis yielded an unrivalled 100% and 99.7% correct class assignment for variety and region of origin, respectively. Prediction of phenolic compound concentrations with A-TEEM based on multivariate calibration models using HPLC reference data was also highly effective, and overall, the A-TEEM technique was shown to be a powerful tool for wine classification and analysis.
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Affiliation(s)
- Ranaweera K R Ranaweera
- Department of Wine Science and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, South Australia 5064, Australia
| | - Adam M Gilmore
- HORIBA Instruments Inc., 20 Knightsbridge Rd., Piscataway, NJ 08854, United States
| | - Dimitra L Capone
- Department of Wine Science and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, UA, PMB 1, Glen Osmond, South Australia 5064, Australia
| | - Susan E P Bastian
- Department of Wine Science and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, UA, PMB 1, Glen Osmond, South Australia 5064, Australia
| | - David W Jeffery
- Department of Wine Science and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, UA, PMB 1, Glen Osmond, South Australia 5064, Australia.
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Gilmore AM. Optimizing Model Calibrations for Natural Product Chemical Compositions with Absorbance-Transmittance Excitation-Emission (A-TEEM) Spectroscopy. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Ranaweera RKR, Gilmore AM, Capone DL, Bastian SEP, Jeffery DW. Authentication of the geographical origin of Australian Cabernet Sauvignon wines using spectrofluorometric and multi-element analyses with multivariate statistical modelling. Food Chem 2020; 335:127592. [PMID: 32750629 DOI: 10.1016/j.foodchem.2020.127592] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/13/2020] [Accepted: 07/13/2020] [Indexed: 01/04/2023]
Abstract
With the increased risk of wine fraud, a rapid and simple method for wine authentication has become a necessity for the global wine industry. The use of fluorescence data from an absorbance and transmission excitation-emission matrix (A-TEEM) technique for discrimination of wines according to geographical origin was investigated in comparison to inductively coupled plasma-mass spectrometry (ICP-MS). The two approaches were applied to commercial Cabernet Sauvignon wines from vintage 2015 originating from three wine regions of Australia, along with Bordeaux, France. Extreme gradient boosting discriminant analysis (XGBDA) was examined among other multivariate algorithms for classification of wines. Models were cross-validated and performance was described in terms of sensitivity, specificity, and accuracy. XGBDA classification afforded 100% correct class assignment for all tested regions using the EEM of each sample, and overall 97.7% for ICP-MS. The novel combination of A-TEEM and XGBDA was found to have great potential for accurate authentication of wines.
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Affiliation(s)
- Ranaweera K R Ranaweera
- Department of Wine and Food Science, and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, South Australia 5064, Australia
| | - Adam M Gilmore
- HORIBA Instruments Inc., 20 Knightsbridge Rd., Piscataway, NJ 08854, United States
| | - Dimitra L Capone
- Department of Wine and Food Science, and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, UA, PMB 1, Glen Osmond, South Australia 5064, Australia
| | - Susan E P Bastian
- Department of Wine and Food Science, and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, UA, PMB 1, Glen Osmond, South Australia 5064, Australia
| | - David W Jeffery
- Department of Wine and Food Science, and Waite Research Institute, The University of Adelaide (UA), PMB 1, Glen Osmond, South Australia 5064, Australia; Australian Research Council Training Centre for Innovative Wine Production, UA, PMB 1, Glen Osmond, South Australia 5064, Australia.
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Gilmore AM, Csatorday K. Characterization of Biopharmaceutical Cell Growth Media by Absorbance-Transmittance Excitation-Emission (A-TEEM) Spectroscopy and Extreme Gradient Boosting Analyses. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Gilmore AM, Chen L. Early Warning Detection of Carcinogens and Other Contaminants for Surface Water Treatment Plants using Simultaneous Absorbance-Transmittance and Fluorescence Excitation-Emission Spectroscopy. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.3053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Quatela A, Gilmore AM, Gall KES, Sandros M, Csatorday K, Siemiarczuk A, Yang B(B, Camenen L. A-TEEMTM, a new molecular fingerprinting technique: simultaneous absorbance-transmission and fluorescence excitation-emission matrix method. Methods Appl Fluoresc 2018; 6:027002. [DOI: 10.1088/2050-6120/aaa818] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gilmore AM, Kitagawa Y, Moriyama T, Irikura D, Nakata Y. Effective Monitoring of Cell Proliferation Media Components using Simultaneous Absorbance and Fluorescence Excitation-Emission Matrix Data Analyzed with Parallel Factor Analysis. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.3144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Gilmore AM, Larkum AWD, Salih A, Itoh S, Shibata Y, Bena C, Yamasaki H, Papina M, Van Woesik R. Simultaneous Time Resolution of the Emission Spectra of Fluorescent Proteins and Zooxanthellar Chlorophyll in Reef-building Corals ¶†. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2003)0770515strote2.0.co2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Gilmore AM, Yamamoto HY. Time-resolution of the Antheraxanthin- and ΔpH-dependent Chlorophyll a Fluorescence Components Associated with Photosystem II Energy Dissipation in Mantoniella squamata¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2001)0740291trotaa2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Li XP, Gilmore AM, Caffarri S, Bassi R, Golan T, Kramer D, Niyogi KK. Regulation of photosynthetic light harvesting involves intrathylakoid lumen pH sensing by the PsbS protein. J Biol Chem 2004; 279:22866-74. [PMID: 15033974 DOI: 10.1074/jbc.m402461200] [Citation(s) in RCA: 373] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biochemical, biophysical, and physiological properties of the PsbS protein were studied in relation to mutations of two symmetry-related, lumen-exposed glutamate residues, Glu-122 and Glu-226. These two glutamates are targets for protonation during lumen acidification in excess light. Mutation of PsbS did not affect xanthophyll cycle pigment conversion or pool size. Plants containing PsbS mutations of both glutamates did not have any rapidly inducible nonphotochemical quenching (qE) and had similar chlorophyll fluorescence lifetime components as npq4-1, a psbS deletion mutant. The double mutant also lacked a characteristic leaf absorbance change at 535 nm (DeltaA535), and PsbS from these plants did not bind dicyclohexylcarbodiimide (DCCD), a known inhibitor of qE. Mutation of only one of the glutamates had intermediate effects on qE, chlorophyll fluorescence lifetime component amplitudes, DCCD binding, and DeltaA535. Little if any differences were observed comparing the two single mutants, suggesting that the glutamates are chemically and functionally equivalent. Based on these results a bifacial model for the functional interaction of PsbS with photosystem II is proposed. Furthermore, based on the extent of qE inhibition in the mutants, photochemical and nonphotochemical quenching processes of photosystem II were associated with distinct chlorophyll fluorescence life-time distribution components.
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Affiliation(s)
- Xiao-Ping Li
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, USA
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Gilmore AM, Larkum AWD, Salih A, Itoh S, Shibata Y, Bena C, Yamasaki H, Papina M, Van Woesik R. Simultaneous time resolution of the emission spectra of fluorescent proteins and zooxanthellar chlorophyll in reef-building corals. Photochem Photobiol 2003; 77:515-23. [PMID: 12812294 DOI: 10.1562/0031-8655(2003)077<0515:strote>2.0.co;2] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Light is absorbed by photosynthetic algal symbionts (i.e. zooxanthellae) and by chromophoric fluorescent proteins (FP) in reef-building coral tissue. We used a streak-camera spectrograph equipped with a pulsed, blue laser diode (50 ps, 405 nm) to simultaneously resolve the fluorescence spectra and kinetics for both the FP and the zooxanthellae. Shallow water (<9 m)-dwelling Acropora spp. and Plesiastrea versipora specimens were collected from Okinawa, Japan, and Sydney, Australia, respectively. The main FP emitted light in the blue, blue-green and green emission regions with each species exhibiting distinct color morphs and spectra. All corals showed rapidly decaying species and reciprocal rises in greener emission components indicating Förster resonance energy transfer (FRET) between FP populations. The energy transfer modes were around 250 ps, and the main decay modes of the acceptor FP were typically 1900-2800 ps. All zooxanthellae emitted similar spectra and kinetics with peak emission (approximately 683 nm) mainly from photosystem II (PSII) chlorophyll (chl) a. Compared with the FP, the PSII emission exhibited similar rise times but much faster decay times, typically around 640-760 ps. The fluorescence kinetics and excitation versus emission mapping indicated that the FP emission played only a minor role, if any, in chl excitation. We thus suggest the FP could only indirectly act to absorb, screen and scatter light to protect PSII and underlying and surrounding animal tissue from excess visible and UV light. We conclude that our time-resolved spectral analysis and simulation revealed new FP emission components that would not be easily resolved at steady state because of their relatively rapid decays due to efficient FRET. We believe the methods show promise for future studies of coral bleaching and for potentially identifying FP species for use as genetic markers and FRET partners, like the related green FP from Aequorea spp.
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Affiliation(s)
- Adam M Gilmore
- Ecosystem Dynamics Group, Research School of Biological Sciences, Australian National University, Institute of Advanced Studies, Canberra, Australian Capital Territory, Australia.
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Li XP, Muller-Moule P, Gilmore AM, Niyogi KK. PsbS-dependent enhancement of feedback de-excitation protects photosystem II from photoinhibition. Proc Natl Acad Sci U S A 2002; 99:15222-7. [PMID: 12417767 PMCID: PMC137571 DOI: 10.1073/pnas.232447699] [Citation(s) in RCA: 336] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2002] [Indexed: 11/18/2022] Open
Abstract
Feedback de-excitation (qE) regulates light harvesting in plants to prevent inhibition of photosynthesis when light absorption exceeds photosynthetic capacity. Although the mechanism of qE is not completely understood, it is known to require a low thylakoid lumen pH, de-epoxidized xanthophylls, and the photosystem II protein PsbS. During a short-term 4-h exposure to excess light, three PsbS- and qE-deficient Arabidopsis thaliana mutants that differed in xanthophyll composition were more photoinhibited than the wild type. The extent of photoinhibition was the same in all of the mutants, suggesting that qE capacity rather than xanthophyll composition is critical for photoprotection in short-term high light, in contrast to longer-term high light conditions (days) when additional antioxidant roles of specific xanthophylls are evident. Plants with a 2-fold increase in qE capacity were generated by overexpression of PsbS, demonstrating that the level of PsbS limits the qE capacity in wild-type Arabidopsis. These results are consistent with the idea that variations in PsbS expression are responsible for species-specific and environmentally induced differences in qE capacity observed in nature. Furthermore, plants with higher qE capacity were more resistant to photoinhibition than the wild type. Increased qE was associated with decreased photosystem II excitation pressure and changes in the fractional areas of chlorophyll a fluorescence lifetime distributions, but not the lifetime centers, suggesting that qE protects from photoinhibition by preventing overreduction of photosystem II electron acceptors. Engineering of qE capacity by PsbS overexpression could potentially yield crop plants that are more resistant to environmental stress.
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Affiliation(s)
- Xiao-Ping Li
- Department of Plant and Microbial Biology, University of California, Berkeley 94720-3102, USA
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Gilmore AM. Advances in understanding acclimation to light stress and light-energy dissipation mechanisms in photosynthetic organisms: an overview of the Light Stress and Photosynthesis meeting (LS2001) and dedicated Special Section papers. Funct Plant Biol 2002; 29:1125-1129. [PMID: 32689565 DOI: 10.1071/fp02127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Adam M Gilmore
- Ecosystem Dynamics Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 0200, Australia.
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Peng CL, Gilmore AM. Comparison of high-light effects with and without methyl viologen indicate barley chlorina mutants exhibit contrasting sensitivities depending on the specific nature of the chlorina mutation: comparison of wild type, chlorophyll-b-less clo f2 and light-sensitive chlorophyll-b-deficient clo f104 mutants. Funct Plant Biol 2002; 29:1171-1180. [PMID: 32689569 DOI: 10.1071/fp02009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This study compared the response to methyl viologen (MV)-induced photooxidation in wild-type barley (wt), and both its chlorina f104-nuclear gene mutant (that restricts Chl a and b synthesis) and its f2-nuclear gene mutant (that inhibits all Chl b synthesis). Without MV, the f2 mutant showed the highest sensitivity to high light, with Fv/Fm being reduced by 80% after 80 min of irradiation. There was little difference in response to high light without MV between f104 and wt. After vacuum infiltration with 100 μM MV and exposure to high light, f104 exhibited the highest sensitivity while f2 was the most tolerant to the photooxidation effects. 77K fluorescence spectral analysis indicated that PSII of f104 was especially damaged, as evidenced by the appearance of a new Chl a emission band around 700 nm at the expense of the F685 and F695 bands from the PSII core-inner antenna. With MV, chlorophyll degraded more rapidly in f104 than in either f2 or wt. During MV treatment, zeaxanthin content increased significantly during the initial period of exposure (0-20 min) in all strains, but decreased sharply in f104 after longer exposure time (20-80 min). β-Carotene, on a chlorophyll basis, was not much changed under high light without MV, but with MV it decreased significantly, mostly in f104, intermediately in f2 and least in wt. We conclude that the light-sensitive chlorosis phenotype of f104 is exacerbated by MV-induced photooxidation.
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Affiliation(s)
- Chang-Lian Peng
- South China Institute of Botany, Chinese Academy of Sciences, Guangzhou 510650, Peoples Republic of China
| | - Adam M Gilmore
- Ecosystem Dynamics Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 0200, Australia. Corresponding author;
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Matsubara S, Gilmore AM, Ball MC, Anderson JM, Osmond CB. Sustained downregulation of photosystem II in mistletoes during winter depression of photosynthesis. Funct Plant Biol 2002; 29:1157-1169. [PMID: 32689568 DOI: 10.1071/fp02014] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Cold acclimation by sustained downregulation of PSII was studied in intact leaves of an Australian mistletoe Amyema miquelii (Lehm. ex Miq.) Tiegh. and its host Eucalyptus. The trends were followed from autumn to spring on leaves that had developed in summer and were exposed to different microclimates with progress of the seasons. In sun leaves of mistletoe, efficiency of excitation energy transfer from light-harvesting pigments to Chl a molecules in PSII core complexes was markedly reduced in winter. Concomitantly, a band in 77K fluorescence emission spectra emerged at 715 nm, in the same way as the cold-hard band found in overwintering snow gum seedlings (Gilmore and Ball 2000, Proceedings of the National Academy of Sciences USA 97, 11 098-11 101). Further, a distinct band, which presumably involves Chl-b-containing antennae complexes, appeared at 705 nm in -2°C fluorescence emission spectra with decreasing intensity of the PSII band. Much shorter PSII fluorescence lifetimes measured in sun leaves of mistletoe that were exhibiting sustained downregulation of PSII indicated enhanced thermal dissipation of excitation energy. Winter acclimation symptoms of the photosynthetic apparatus were more striking in mistletoe sun leaves compared with eucalypt sun leaves. Because the light and temperature environments of sun leaves are similar for the parasite and host, we primarily attribute the enhanced light-acclimation symptoms to the limited photosynthetic capacity of A. miquelii in winter.
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Affiliation(s)
- Shizue Matsubara
- Photobioenergetics Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 0200, Australia. Corresponding author;
| | - Adam M Gilmore
- Ecosystem Dynamics Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 0200, Australia
| | - Marilyn C Ball
- Ecosystem Dynamics Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 0200, Australia
| | - Jan M Anderson
- Photobioenergetics Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 0200, Australia
| | - C Barry Osmond
- Biosphere 2 Center, Columbia University, Box 689, Oracle, AZ 85623, USA
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Li XP, Gilmore AM, Niyogi KK. Molecular and global time-resolved analysis of a psbS gene dosage effect on pH- and xanthophyll cycle-dependent nonphotochemical quenching in photosystem II. J Biol Chem 2002; 277:33590-7. [PMID: 12110676 DOI: 10.1074/jbc.m204797200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Photosynthetic light harvesting in plants is regulated by a pH- and xanthophyll-dependent nonphotochemical quenching process (qE) that dissipates excess absorbed light energy and requires the psbS gene product. An Arabidopsis thaliana mutant, npq4-1, lacks qE because of a deletion of the psbS gene, yet it exhibits a semidominant phenotype. Here it is shown that the semidominance is due to a psbS gene dosage effect. Diploid Arabidopsis plants containing two psbS gene copies (wild-type), one psbS gene (npq4-1/NPQ4 heterozygote), and no psbS gene (npq4-1/npq4-1 homozygote) were compared. Heterozygous plants had 56% of the wild-type psbS mRNA level, 58% of the wild-type PsbS protein level, and 60% of the wild-type level of qE. Global analysis of the chlorophyll a fluorescence lifetime distributions revealed three components in wild-type and heterozygous plants, but only a single long lifetime component in npq4-1. The short lifetime distribution associated with qE was inhibited by more than 40% in heterozygous plants compared with the wild type. Thus, the extent of qE measured as either the fractional intensities of the PSII chlorophyll a fluorescence lifetime distributions or steady state intensities was stoichiometrically related to the amount of PsbS protein.
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Affiliation(s)
- Xiao-Ping Li
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720-3102, USA
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Gilmore AM, Yamamoto HY. Time-resolution of the antheraxanthin- and delta pH-dependent chlorophyll a fluorescence components associated with photosystem II energy dissipation in Mantoniella squamata. Photochem Photobiol 2001; 74:291-302. [PMID: 11547568 DOI: 10.1562/0031-8655(2001)074<0291:trotaa>2.0.co;2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The electronic excited-state behavior of photosystem II (PSII) in Mantoniella squamata, as influenced by the xanthophyll cycle and the transthylakoid pH gradient (delta pH), was examined in vivo. Mantoniella is distinguished from other photosynthetic organisms by two main features namely (1) a unique light-harvesting complex that serves both photosystems I (PSI) and II (PSII); and (2) a violaxanthin (V) cycle that undergoes only one de-epoxidation step in excess light to accumulate the monoepoxide antheraxanthin (A) as opposed to the epoxide-free zeaxanthin (Z). The cells were treated first with high light to induce the delta pH and A accumulation, followed by herbicide-induced closure of PSII traps and a chilling treatment, to sustain and stabilize the delta pH and nigericin-sensitive fluorescence level in the dark. De-epoxidation was controlled with subsaturating concentrations of dithiothreitol (DTT) and was 5-10 times more sensitive to DTT than higher plant thylakoids. The PSII energy dissipation involved two steps: (1) the pH activation of the xanthophyll binding site that was associated with a narrowing and slight attenuation of the main 2 ns (ns = 10(-9) s) fluorescence lifetime distribution; and (2) the concentration-dependent binding of A to the activated binding site yielding a second distribution centered around 0.9 ns. Consistent with the model of Gilmore et al. (1998) (Biochemistry 37, 13,582-13,593), the fractional intensity of the 0.9 ns component depended almost entirely on the A concentration and correlated linearly with the decrease of the steady-state chlorophyll alpha fluorescence intensity.
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Affiliation(s)
- A M Gilmore
- Ecosystem Dynamics Group, Research School of Biological Sciences, Institute of Advanced Studies, Australian National University, Canberra, Australia.
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23
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Gilmore AM. Xanthophyll cycle-dependent nonphotochemical quenching in Photosystem II: Mechanistic insights gained from Arabidopsis thaliana L. mutants that lack violaxanthin deepoxidase activity and/or lutein. Photosynth Res 2001; 67:89-101. [PMID: 16228319 DOI: 10.1023/a:1010657000548] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
This study compares Photosystem II (PS II) chlorophyll (Chl) a fluorescence yield changes of Arabidopsis thaliana L. nuclear gene mutants, thoughtfully provided by the authors of Pogson et al. (1998 Proc Natl Acad Sci USA 95: 13324-13329). One single mutant (npq1) inhibits the violaxanthin deepoxidase that converts violaxanthin to antheraxanthin and zeaxanthin. A second single mutant (lut2) inhibits the in-cyclization enzyme step between lycopene and beta,in-carotene causing accumulation of beta,beta-carotene derivatives, primarily the violaxanthin cycle pigments, at the expense of lutein. The double mutant (lut2-npq1) incorporates both lesions. PS II Chl a fluorescence was characterized in leaves and thylakoids using both steady state and time-resolved methods, the intrathylakoid pH was estimated by 9-aminoacridine fluorescence quenching and chloroplast pigments were determined by HPLC. Under maximal PS II Chl a fluorescence intensity conditions without intrathylakoid acidification, the main 2 nanosecond (ns) fluorescence lifetime distribution mode parameters were similar for the WT and mutants both before and after illumination. The light and ATPase mediated intrathylakoid pH levels were also similar and caused similar changes in the fluorescence lifetime distribution widths and centers for the WT and each mutant. The npq1 exhibited low antheraxanthin and zeaxanthin and high violaxanthin levels and the uncoupler-sensitive amplitudes of short (< 1 ns) PS II Chl a fluorescence distribution modes were strongly inhibited compared to the WT. Lutein deficiency coincided with pleiotropic effects on PS II energy dissipation and probably altered conformations of PS II carotenoid-chlorophyll binding proteins. The lut2 exhibited separate active and inactive pools of antheraxanthin and zeaxanthin with respect to all deepoxidation, epoxidation and fluorescence quenching activities. The active xanthophyll cycle pool in lut2 exhibited a lower ( approximately 35% of WT) concentration efficiency, for a given intrathylakoid pH, to increase the sub-nanosecond distribution amplitudes, which predicts and explains inhibited induction kinetics and fluorescence quenching. The lut2-npq1 mutant exhibited a constant pool of antheraxanthin and zeaxanthin, no deepoxidation and little or no pH-reversible fluorescence decrease. It is concluded that in addition to intrathylakoid acidification, a certain level of zeaxanthin and antheraxanthin (or lutein) is absolutely required for the major reversible component of PS II Chl a fluorescence quenching.
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Affiliation(s)
- A M Gilmore
- Ecosystem Dynamics Group, Research School of Biological Sciences, Institute of Advanced Studies, Australian National University, Canberra, ACT, 0200, Australia,
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Abstract
How evergreen species store and protect chlorophyll during exposure to high light in winter remains unexplained. This study reveals that the evergreen snow gum (Eucalyptus pauciflora Sieb. ex Spreng.) stores and protects its chlorophylls by forming special complexes that are unique to the winter-acclimated state. Our in vivo spectral and kinetic characterizations reveal a prominent component of the chlorophyll fluorescence spectrum around 715 nm at 77 K. This band coincides structurally with a loss of chlorophyll and an increase in energy-dissipating carotenoids. Functionally, the band coincides with an increased capacity to dissipate excess light energy, absorbed by the chlorophylls, as heat without intrathylakoid acidification. The increased heat dissipation helps protect the chlorophylls from photo-oxidative bleaching and thereby facilitates rapid recovery of photosynthesis in spring.
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Affiliation(s)
- A M Gilmore
- Photobioenergetics Group and Ecosystem Dynamics Group, Research School of Biological Sciences, Institute of Advanced Studies, Australian National University, Canberra ACT 0200, Australia.
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Gilmore AM, Shinkarev VP, Hazlett TL, Govindjee G. Quantitative analysis of the effects of intrathylakoid pH and xanthophyll cycle pigments on chlorophyll a fluorescence lifetime distributions and intensity in thylakoids. Biochemistry 1998; 37:13582-93. [PMID: 9753445 DOI: 10.1021/bi981384x] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The xanthophyll cycle-dependent dissipation of excitation energy in higher plants is one of the most important regulatory and photoprotective mechanisms in photosynthesis. Using parallel time-resolved and pulse-amplitude modulation fluorometry, we studied the influence of the intrathylakoid pH and the xanthophyll cycle carotenoids on the PSII chlorophyll (Chl) a fluorescence yield in thylakoids of Arabidopsis, spinach, and barley. Increases in concentrations of dithiothreitol in thylakoids, which have a trans-thylakoid membrane pH gradient and are known to have decreased conversion of violaxanthin (V) to zeaxanthin (Z), lead to (1) decreases in the fractional intensity of the approximately 0.5 ns Chl a fluorescence lifetime (tau) distribution component and simultaneous increases in a 1.6-1.8 ns fluorescence component and (2) increases in the maximal fluorescence intensity. These effects disappear when the pH gradient is eliminated by the addition of nigericin. To quantitatively explain these results, we present a new mathematical model that describes the simultaneous effects of the chloroplast trans-thylakoid membrane pH gradient and xanthophyll cycle pigments on the PSII Chl a fluorescence tau distributions and intensity. The model assumes that (1) there exists a specific binding site for Z (or antheraxanthin, A) among or in an inner antenna complex (primarily CP29), (2) this binding site is activated by a low intrathylakoid pH (pK approximately 4.5) that increases the affinity for Z (or A), (3) about one Z or A molecule binds to the activated site, and (4) this binding effectively "switches" the fluorescence tau distribution of the PSII unit to a state with a decreased fluorescence tau and emission intensity (a "dimmer switch" concept). This binding is suggested to cause the formation of an exciton trap with a rapid intrinsic rate constant of heat dissipation. Statistical analysis of the data yields an equilibrium association constant, Ka, that ranges from 0.7 to 3.4 per PSII for the protonated/activated binding site for Z (or A). The model explains (1) the relative fraction of the approximately 0.5 ns fluorescence component as a function of both Z and A concentration and intrathylakoid pH, (2) the dependence of the ratio of F'm/Fm on the fraction of the 0.5 ns fluorescence tau component (where F'm and Fm are maximal fluorescence intensities in the presence and the absence of a pH gradient), and (3) the dependence of the ratio of F'm/Fm on the concentration of Z and A and the intrathylakoid pH.
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Affiliation(s)
- A M Gilmore
- Photobioenergetics Group, Australian National University Research School of Biological Sciences, Canberra, ACT.
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Gilmore AM, Hazlett TL, Debrunner PG. Comparative time-resolved photosystem II chlorophyll a fluorescence analyses reveal distinctive differences between photoinhibitory reaction center damage and xanthophyll cycle-dependent energy dissipation. Photochem Photobiol 1996; 64:552-63. [PMID: 8806231 DOI: 10.1111/j.1751-1097.1996.tb03105.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The photosystem II (PSII) reaction center in higher plants is susceptible to photoinhibitory molecular damage of its component pigments and proteins upon prolonged exposure to excess light in air. Higher plants have a limited capacity to avoid such damage through dissipation, as heat, of excess absorbed light energy in the PSII light-harvesting antenna. The most important photoprotective heat dissipation mechanism, induced under excess light conditions, includes a concerted effect of the trans-thylakoid pH gradient (delta pH) and the carotenoid pigment interconversions of the xanthophyll cycle. Coincidentally, both the photoprotective mechanism and photoinhibitory PSII damage decrease the PSII chlorophyll a (Chl a) fluorescence yield. In this paper we present a comparative fluorescence lifetime analysis of the xanthophyll cycle- and photoinhibition-dependent changes in PSII Chl a fluorescence. We analyze multifrequency phase and modulation data using both multicomponent exponential and bimodal Lorentzian fluorescence lifetime distribution models; further, the lifetime data were obtained in parallel with the steady-state fluorescence intensity. The photoinhibition was characterized by a progressive decrease in the center of the main fluorescence lifetime distribution from approximately 2 ns to approximately 0.5 ns after 90 min of high light exposure. The damaging effects were consistent with an increased nonradiative decay path for the charge-separated state of the PSII reaction center. In contrast, the delta pH and xanthophyll cycle had concerted minor and major effects, respectively, on the PSII fluorescence lifetimes and intensity (Gilmore et al., 1996, Photosynth. Res., in press). The minor change decreased both the width and lifetime center of the longest lifetime distribution; we suggest that this change is associated with the delta pH-induced activation step, needed for binding of the deepoxidized xanthophyll cycle pigments. The major change increased the fractional intensity of a short lifetime distribution at the expense of a longer lifetime distribution; we suggest that this change is related to the concentration-dependent binding of the deepoxidized xanthophylls in the PSII inner antenna. Further, both the photoinhibition and xanthophyll cycle mechanisms had different effects on the relationship between the fluorescence lifetimes and intensity. The observed differences between the xanthophyll cycle and photoinhibition mechanisms confirm and extend our current basic model of PSII exciton dynamics, structure and function.
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Affiliation(s)
- A M Gilmore
- Department of Plant Biology, University of Illinois at Urbana-Champaign 61801-3707, USA
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27
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Gilmore AM, Hazlett TL, Debrunner PG. Photosystem II chlorophyll a fluorescence lifetimes and intensity are independent of the antenna size differences between barley wild-type and chlorina mutants: Photochemical quenching and xanthophyll cycle-dependent nonphotochemical quenching of fluorescence. Photosynth Res 1996; 48:171-187. [PMID: 24271297 DOI: 10.1007/bf00041007] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/1995] [Accepted: 02/14/1996] [Indexed: 06/02/2023]
Abstract
Photosystem II (PS II) chlorophyll (Chl) a fluorescence lifetimes were measured in thylakoids and leaves of barley wild-type and chlorina f104 and f2 mutants to determine the effects of the PS II Chl a+b antenna size on the deexcitation of absorbed light energy. These barley chlorina mutants have drastically reduced levels of PS II light-harvesting Chls and pigment-proteins when compared to wild-type plants. However, the mutant and wild-type PS II Chl a fluorescence lifetimes and intensity parameters were remarkably similar and thus independent of the PS II light-harvesting antenna size for both maximal (at minimum Chl fluorescence level, Fo) and minimal rates of PS II photochemistry (at maximum Chl fluorescence level, Fm). Further, the fluorescence lifetimes and intensity parameters, as affected by the trans-thylakoid membrane pH gradient (ΔpH) and the carotenoid pigments of the xanthophyll cycle, were also similar and independent of the antenna size differences. In the presence of a ΔpH, the xanthophyll cycle-dependent processes increased the fractional intensity of a Chl a fluorescence lifetime distribution centered around 0.4-0.5 ns, at the expense of a 1.6 ns lifetime distribution (see Gilmore et al. (1995) Proc Natl Acad Sci USA 92: 2273-2277). When the zeaxanthin and antheraxanthin concentrations were measured relative to the number of PS II reaction center units, the ratios of fluorescence quenching to [xanthophyll] were similar between the wild-type and chlorina f104. However, the chlorina f104, compared to the wild-type, required around 2.5 times higher concentrations of these xanthophylls relative to Chl a+b to obtain the same levels of xanthophyll cycle-dependent fluorescence quenching. We thus suggest that, at a constant ΔpH, the fraction of the short lifetime distribution is determined by the concentration and thus binding frequency of the xanthophylls in the PS II inner antenna. The ΔpH also affected both the widths and centers of the lifetime distributions independent of the xanthophyll cycle. We suggest that the combined effects of the xanthophyll cycle and ΔpH cause major conformational changes in the pigment-protein complexes of the PS II inner or core antennae that switch a normal PS II unit to an increased rate constant of heat dissipation. We discuss a model of the PS II photochemical apparatus where PS II photochemistry and xanthophyll cycle-dependent energy dissipation are independent of the Peripheral antenna size.
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Affiliation(s)
- A M Gilmore
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 61801-3707, Urbana, IL, USA
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Abstract
The function of the long-chain, highly unsaturated carotenoids of higher plants in photoprotection is becoming increasingly well understood, while at the same time their function in other processes, such as light collection, needs to be reexamined. Recent progress in this area has been fueled by more accurate determinations of the photophysical properties of these molecules, as well as extensive characterization of the physiology and ecology of a particular group of carotenoids, those of the xanthophyll cycle, that play a key role in the photoprotection of photosynthesis under environmental stress. The deepoxidized xanthophylls zeaxanthin and antheraxanthin, together with a low pH within the photosynthetic membrane, facilitate the harmless dissipation of excess excitation energy directly within the light-collecting chlorophyll antennae. Evidence for this function as well as current contrasting hypotheses concerning its molecular mechanism are reviewed. In addition, the acclimation of the xanthophyll cycle content and composition of leaves to contrasting environments with different demands for photoprotection is summarized.
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Affiliation(s)
- B Demmig-Adams
- Department of Environmental, Organismic, and Population Biology, University of Colorado, Boulder 80309-0334, USA
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Gilmore AM, Hazlett TL. Xanthophyll cycle-dependent quenching of photosystem II chlorophyll a fluorescence: formation of a quenching complex with a short fluorescence lifetime. Proc Natl Acad Sci U S A 1995; 92:2273-7. [PMID: 11607518 PMCID: PMC42466 DOI: 10.1073/pnas.92.6.2273] [Citation(s) in RCA: 202] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Excess light triggers protective nonradiative dissipation of excitation energy in photosystem II through the formation of a trans-thylakoid pH gradient that in turn stimulates formation of zeaxanthin and antheraxanthin. These xanthophylls when combined with protonation of antenna pigment-protein complexes may increase nonradiative dissipation and, thus, quench chlorophyll a fluorescence. Here we measured, in parallel, the chlorophyll a fluorescence lifetime and intensity to understand the mechanism of this process. Increasing the xanthophyll concentration in the presence of a pH gradient (quenched conditions) decreases the fractional intensity of a fluorescence lifetime component centered at approximately 2 ns and increases a component at approximately 0.4 ns. Uncoupling the pH gradient (unquenched conditions) eliminates the 0.4-ns component. Changes in the xanthophyll concentration do not significantly affect the fluorescence lifetimes in either the quenched or unquenched sample conditions. However, there are differences in fluorescence lifetimes between the quenched and unquenched states that are due to pH-related, but nonxanthophyll-related, processes. Quenching of the maximal fluorescence intensity correlates with both the xanthophyll concentration and the fractional intensity of the 0.4-ns component. The unchanged fluorescence lifetimes and the proportional quenching of the maximal and dark-level fluorescence intensities indicate that the xanthophylls act on antenna, not reaction center processes. Further, the fluorescence quenching is interpreted as the combined effect of the pH gradient and xanthophyll concentration, resulting in the formation of a quenching complex with a short (approximately 0.4 ns) fluorescence lifetime.
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Affiliation(s)
- A M Gilmore
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Gilmore AM, Mohanty N, Yamamoto HY. Epoxidation of zeaxanthin and antheraxanthin reverses non-photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans-thylakoid delta pH. FEBS Lett 1994; 350:271-4. [PMID: 8070578 DOI: 10.1016/0014-5793(94)00784-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The xanthophyll cycle apparently aids the photoprotection of photosystem II by regulating the nonradiative dissipation of excess absorbed light energy as heat. However, it is a controversial question whether the resulting nonphotochemical quenching is soley dependent on xanthophyll cycle activity or not. The xanthophyll cycle consists of two enzymic reactions, namely deepoxidation of the diepoxide violaxanthin to the epoxide-free zeaxanthin and the much slower, reverse process of epoxidation. While deepoxidation requires a transthylakoid pH gradient (delta pH), epoxidation can proceed irrespective of a delta pH. Herein, we compared the extent and kinetics of deepoxidation and epoxidation to the changes in fluorescence in the presence of a light-induced thylakoid delta pH. We show that epoxidation reverses fluorescence quenching without affecting thylakoid delta pH. These results suggest that epoxidase activity reverses quenching by removing deepoxidized xanthophyll cycle pigments from quenching complexes and converting them to a nonquenching form. The transmembrane organization of the xanthophyll cycle influences the localization and the availability of deepoxidized xanthophylls is to support nonphotochemical quenching capacity. The results confirm the view that rapidly reversible nonphotochemical quenching is dependent on deepoxidized xanthophyll.
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Affiliation(s)
- A M Gilmore
- University of Hawaii, Department of Plant Molecular Physiology, Honolulu 96822
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Gilmore AM, Yamamoto HY. Linear models relating xanthophylls and lumen acidity to non-photochemical fluorescence quenching. Evidence that antheraxanthin explains zeaxanthin-independent quenching. Photosynth Res 1993; 35:67-78. [PMID: 24318621 DOI: 10.1007/bf02185412] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/1992] [Accepted: 07/27/1992] [Indexed: 05/09/2023]
Abstract
Zeaxanthin has been correlated with high-energy non-photochemical fluorescence quenching but whether antheraxanthin, the intermediate in the pathway from violaxanthin to zeaxanthin, also relates to quenching is unknown. The relationships of zeaxanthin, antheraxanthin and ΔpH to fluorescence quenching were examined in chloroplasts ofPisum sativum L. cv. Oregon andLactuca sativa L. cv. Romaine. Data matrices as five levels of violaxanthin de-epoxidation against five levels of light-induced lumen-proton concentrations were obtained for both species. The matrices included high levels of antheraxanthin as well as lumen-proton concentrations induced by subsaturating to saturation light levels. Analyses of the matrices by simple linear and multiple regression showed that quenching is predicted by models where the major independent variable is the product of lumen acidity and de-epoxidized xanthophylls, the latter as the sum of zeaxanthin and antheraxanthin. The interactions of lumen acidity and xanthophyll concentration are shown in three-dimensional plots of the best-fit multiple regression models. Antheraxanthin apparently contributes to quenching as effectively as zeaxanthin and explains quenching previously not accounted for by zeaxanthin. Hence, we propose that all high-energy dependent quenching is xanthophyll dependent. Quenching requires a threshold lumen pH that varies with xanthophyll composition. After the threshold, quenching is linear with lumen acidity or xanthophyll composition.
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Affiliation(s)
- A M Gilmore
- Department of Plant Molecular Physiology, University of Hawaii at Manoa, 3190 Maile Way, St. John 503, 96822, Honolulu, Hawaii, USA
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Abstract
Zeaxanthin-dependent nonphotochemical fluorescence quenching is a light-induced activity in plants that apparently protects against the potentially damaging effects of excess light. We report a dark-induced nonphotochemical quenching in thylakoids of Lactuca sativa L. cv. Romaine mediated by ATP. This effect is due to low lumen pH from hydrolysis-dependent proton pumping and hence required an active ATPase. The induction was optimal at 0.3 mM ATP, a physiological concentration, and occurred under conditions of little or no reverse electron flow. The properties of ATP-induced quenching were in all respects examined similar to light-induced quenching, including antimycin inhibition of quenching induction but not delta pH. We conclude that zeaxanthin-dependent quenching depends directly on lumen pH and that the role of light is indirect. Although it is known that zeaxanthin and low lumen pH are insufficient for quenching to occur, the results apparently exclude the redox state of an electron-transport carrier or formation of light-induced carotenoid triplets as a further requirement. We propose that a slow pH-dependent conformational change together with zeaxanthin cause static quenching in the pigment bed; possibly antimycin inhibits this change. Furthermore, we suggest from the ability of ATP to sustain quenching in the dark for extended periods that persistent or slowly reversible zeaxanthin quenching often observed in vivo may be due to sustained delta pH from ATP hydrolysis.
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Affiliation(s)
- A M Gilmore
- University of Hawaii, Department of Plant Molecular Physiology, Honolulu 96822
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Gilmore AM, Yamamoto HY. Zeaxanthin Formation and Energy-Dependent Fluorescence Quenching in Pea Chloroplasts under Artificially Mediated Linear and Cyclic Electron Transport. Plant Physiol 1991; 96:635-43. [PMID: 16668233 PMCID: PMC1080818 DOI: 10.1104/pp.96.2.635] [Citation(s) in RCA: 155] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Artificially mediated linear (methylviologen) and cyclic (phenazine methosulfate) electron transport induced zeaxanthin-dependent and independent (constitutive) nonphotochemical quenching in osmotically shocked chloroplasts of pea (Pisum sativum L. cv Oregon). Nonphotochemical quenching was quantitated as Stern-Volmer quenching (SV(N)) calculated as (F(m)/F'(m))-1 where F(m) is the fluorescence intensity with all PSII reaction centers closed in a nonenergized, dark-adapted state and F'(m) is the fluorescence intensity with all PSII reaction centers closed in an energized state. Reversal of quenching by nigericin and electron-transport inhibitors showed that both quenching types were energy-dependent SV(N). Under light-induced saturating DeltapH, constitutive-SV(N) reached steady-state in about 1 minute whereas zeaxanthin-SV(N) continued to develop for several minutes in parallel with the slow kinetics of violaxanthin deepoxidation. SV(N) above the constitutive level and relative zeaxanthin concentration showed high linear correlations at steady-state and during induction. Furthermore, F(o) quenching, also treated as Stern-Volmer quenching (SV(O)) and calculated as (F(o)/F'(o))-1, showed high correlation with zeaxanthin and consequently with SV(N) (F(o) and F'(o) are fluorescence intensities with all PSII reaction centers in nonenergized and energized states, respectively). These results support the view that zeaxanthin increases SV(N) above the constitutive level in a concentration-dependent manner and that zeaxanthin-dependent SV(N) occurs in the pigment bed. Preforming zeaxanthin increased the rate and extent of SV(N), indicating that slow events other than the amount of zeaxanthin also affect final zeaxanthin-SV(N) expression. The redox state of the primary electron acceptor of photosystem II did not appear to determine SV(N). Antimycin, when added while chloroplasts were in a dark-adapted or nonenergized state, inhibited both zeaxanthin-SV(N) and constitutive-SV(N) induced by linear and cyclic electron transport. These similarities, including possible constitutive F(o) quenching, suggest that zeaxanthin-dependent and constitutive SV(N) are mechanistically related.
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Affiliation(s)
- A M Gilmore
- University of Hawaii, Department of Plant Molecular Physiology, 3190 Maile Way, St. John 503, Honolulu, Hawaii 96822
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Gilmore AM, Yamamoto HY. Resolution of lutein and zeaxanthin using a non-endcapped, lightly carbon-loaded C18 high-performance liquid chromatographic column. J Chromatogr A 1991. [DOI: 10.1016/s0021-9673(01)95762-0] [Citation(s) in RCA: 237] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
A pilot study was undertaken to investigate the reliability of the 'expert judgement' exercised in marking state examination papers. Estimates of inter-rater reliability had a median coefficient of 0.76. Intra-rater reliability was marginally higher overall, with a median coefficient of 0.81. While marker reliability is only one source of variation in the assessment of extended answers, it is important the level be known. This study provides useful information and guidelines for improvements.
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Gilmore AM, McCarthy CF, Feighery C, Weir DG, O'Neill M, Whelton M, Henry RW, Kelly H, Love AH. The use of gliptide in patients with duodenal ulcers. Ir Med J 1977; 70:615-7. [PMID: 340416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Abstract
A survey of the terrestrial vertebrate fauna of the Dartmouth Dam inundation area has shown the presence of 24 mammal, 100 bird, 24 reptile, and 10 anuran species.
Some aspects of their ecology, including habitat occupancy, are discussed, and the trapping success for eight small mammal species in different habitats is compared.
A zoogeographic analysis of the fauna demonstrates its heterogeneous and transitional nature, and it is probable that the unique community will be totally lost from the Mitta Mitta River Valley.
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