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Govindjee. A sixty-year tryst with photosynthesis and related processes: an informal personal perspective. PHOTOSYNTHESIS RESEARCH 2019; 139:15-43. [PMID: 30343396 DOI: 10.1007/s11120-018-0590-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 10/01/2018] [Indexed: 06/08/2023]
Abstract
After briefly describing my early collaborative work at the University of Allahabad, that had laid the foundation of my research life, I present here some of our research on photosynthesis at the University of Illinois at Urbana-Champaign, randomly selected from light absorption to NADP+ reduction in plants, algae, and cyanobacteria. These include the fact that (i) both the light reactions I and II are powered by light absorbed by chlorophyll (Chl) a of different spectral forms; (ii) light emission (fluorescence, delayed fluorescence, and thermoluminescence) by plants, algae, and cyanobacteria provides detailed information on these reactions and beyond; (iii) primary photochemistry in both the photosystems I (PS I) and II (PS II) occurs within a few picoseconds; and (iv) most importantly, bicarbonate plays a unique role on the electron acceptor side of PS II, specifically at the two-electron gate of PS II. Currently, the ongoing research around the world is, and should be, directed towards making photosynthesis better able to deal with the global issues (such as increasing population, dwindling resources, and rising temperature) particularly through genetic modification. However, basic research is necessary to continue to provide us with an understanding of the molecular mechanism of the process and to guide us in reaching our goals of increasing food production and other chemicals we need for our lives.
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Herbert SK, Siderer Y. Shmuel Malkin (1934-2017) : Listening to photosynthesis and making music. PHOTOSYNTHESIS RESEARCH 2018; 137:1-15. [PMID: 29383630 DOI: 10.1007/s11120-018-0478-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 12/31/2017] [Indexed: 06/07/2023]
Abstract
We present here the life and work of Shmuel Malkin (1934-2017), an accomplished scientist and a gifted musician who touched the lives of many around the world. His early scientific work addressed the dynamics of light harvesting and electron transport in photosynthesis. Later, he used photoacoustic and photothermal methodologies to explore all aspects of photosynthesis. As a musician, Shmuel played the piano often for family and friends but after his formal retirement, he produced a body of original musical compositions, many of which were performed publicly. Throughout his life, Shmuel was a caring and deeply thoughtful man, respected and loved by colleagues, family, and friends. This tribute presents a summary of Shmuel's work as well as remembrances written by his wife, Nava Malkin, their son, Eyal Malkinson, and many of his colleagues: Michael Havaux from France; Sandra and Marcel Jansen from Ireland; David Cahen, Marvin Edelmann, Joop and Onnie de Graaf, Jonathan Gressel, Uri Pick, Yona Siderer, and Elisha Tel-Or from Israel; Ulrich Schreiber from Germany; James Barber and Alison Telfer from the UK; Govindjee, Stephen Herbert and Thomas Sharkey from the USA. Minnie Ho and Iris Malkin of the USA wrote contributions about Shmuel's music.
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Affiliation(s)
| | - Yona Siderer
- Edelstein Center for History and Philosophy of Science, Technology and Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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Zivcak M, Brestic M, Kalaji HM. Photosynthetic responses of sun- and shade-grown barley leaves to high light: is the lower PSII connectivity in shade leaves associated with protection against excess of light? PHOTOSYNTHESIS RESEARCH 2014; 119:339-54. [PMID: 24445618 PMCID: PMC3923118 DOI: 10.1007/s11120-014-9969-8] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 12/30/2013] [Indexed: 05/03/2023]
Abstract
In this study, we have compared photosynthetic performance of barley leaves (Hordeum vulgare L.) grown under sun and shade light regimes during their entire growth period, under field conditions. Analyses were based on measurements of both slow and fast chlorophyll (Chl) a fluorescence kinetics, gas exchange, pigment composition; and of light incident on leaves during their growth. Both the shade and the sun barley leaves had similar Chl a/b and Chl/carotenoid ratios. The fluorescence induction analyses uncovered major functional differences between the sun and the shade leaves: lower connectivity among Photosystem II (PSII), decreased number of electron carriers, and limitations in electron transport between PSII and PSI in the shade leaves; but only low differences in the size of PSII antenna. We discuss the possible protective role of low connectivity between PSII units in shade leaves in keeping the excitation pressure at a lower, physiologically more acceptable level under high light conditions.
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Affiliation(s)
- Marek Zivcak
- Department of Plant Physiology, Slovak Agricultural University, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic
| | - Marian Brestic
- Department of Plant Physiology, Slovak Agricultural University, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic
| | - Hazem M. Kalaji
- Department of Plant Physiology, Faculty of Agriculture and Biology, Warsaw Agricultural University SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
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Papageorgiou GC, Govindjee. Photosystem II fluorescence: slow changes--scaling from the past. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2011; 104:258-70. [PMID: 21530301 DOI: 10.1016/j.jphotobiol.2011.03.008] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/14/2011] [Accepted: 03/14/2011] [Indexed: 11/25/2022]
Abstract
With the advent of photoelectric devices (photocells, photomultipliers) in the 1930s, fluorometry of chlorophyll (Chl) a in vivo emerged as a major method in the science of photosynthesis. Early researchers employed fluorometry primarily for two tasks: to elucidate the role in photosynthesis, if any, of other plant pigments, such as Chl b, Chl c, carotenoids and phycobilins; and to use it as a convenient inverse measure of photosynthetic activity. In pursuing the latter task, it became apparent that Chl a fluorescence emission is influenced (i) by redox active Chl a molecules in the reaction center of photosystem (PS) II (photochemical quenching); (ii) by an electrochemical imbalance across the thylakoid membrane (high energy quenching); and (iii) by the size of the peripheral antennae of weakly fluorescent PSI and strongly fluorescent PSII in response to changes in the ambient light (state transitions). In this perspective we trace the historical evolution of our awareness of these concepts, particularly of the so-called 'State Transitions'.
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Affiliation(s)
- George C Papageorgiou
- National Center of Scientific Research Demokritos, Institute of Biology, Athens 15310, Greece.
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Dewar BJ, Bradford BU, Thurman RG. Nicotine increases hepatic oxygen uptake in the isolated perfused rat liver by inhibiting glycolysis. J Pharmacol Exp Ther 2002; 301:930-7. [PMID: 12023521 DOI: 10.1124/jpet.301.3.930] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nicotine influences energy metabolism, yet mechanisms remain unclear. Since the liver is one of the largest organs and performs many metabolic functions, the goal of this study was to determine whether nicotine would affect respiration and other metabolic functions in the isolated perfused liver. Infusion of 85 microM nicotine caused a rapid 10% increase in oxygen uptake over basal values of 105 +/- 5 micromol/g/h in perfused livers from fed rats, and an increase of 27% was observed with 850 microM nicotine. Concomitantly, rates of glycolysis of 105 +/- 8 micromol/g/h were decreased to 52 +/- 9 micromol/g/h with nicotine, whereas ketone body production was unaffected. Nicotine had no effect on oxygen uptake in glycogen-depleted livers from 24-h fasted rats. Furthermore, addition of glucose to perfused livers from fasted rats partially restored the stimulatory effect of nicotine. Infusion of atractyloside, potassium cyanide, or glucagon blocked the nicotine-induced increase in respiration. Intracellular calcium was increased in isolated hepatocytes by nicotine, a phenomenon prevented by incubation of cells with d-tubocurarine, a nicotinic acetylcholine receptor antagonist. Respiration was also increased approximately 30% in hepatocytes isolated from fed rats by nicotine, whereas hepatocytes isolated from fasted rats showed little response. In the presence of N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), an inhibitor of cyclic AMP-dependent protein kinase A, nicotine failed to stimulate respiration. These data support the hypothesis that inhibition of glycolysis by nicotine increases oxygen uptake due to an ADP-dependent increase in mitochondrial respiration.
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Affiliation(s)
- Brian J Dewar
- Laboratory of Hepatobiology and Toxicology, Department of Pharmacology, CB #7365, Mary Ellen Jones Building, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Antagonistic effects of mono- and divalent cations on polarization of chlorophyll fluorescence in thylakoids and changes in excitation energy transfer. FEBS Lett 2001. [DOI: 10.1016/0014-5793(79)80124-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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8
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Moya I, Hodges M, Barbet JC. Modification of room-temperature picosecond chlorophyll fluorescence kinetics in green algae by photosystem II trap closure. FEBS Lett 2001. [DOI: 10.1016/0014-5793(86)80416-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Hodges M, Briantais JM, Moya I. The effect of thylakoid membrane reorganisation on chlorophyll fluorescence lifetime components: A comparison between state transitions, protein phosphorylation and the absence of Mg2+. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1987. [DOI: 10.1016/0005-2728(87)90099-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Moya I, Hodges M, Briantais JM, Hervo G. Evidence that the variable chlorophyll fluorescence in Chlamydomonas reinhardtii is not recombination luminescence. PHOTOSYNTHESIS RESEARCH 1986; 10:319-325. [PMID: 24435379 DOI: 10.1007/bf00118297] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Room temperature single photon timing measurements on intact, Chlamydomonas reinhardtii cells at low excitation energies have been analysed using a four exponential kinetic model. Closing the PSII reaction centres produced two major variable lifetime and two minor constant lifetime components. The yield of each component mirrored the changes in lifetime. Such observations indicate the presence of well-connected PSII centres favoring excitation energy transfer. A Chlamydomonas mutant lacking PSII reaction centre proteins exhibited decay components equivalent to those seen at FM in the wild-type. A titration of in vivo fluorescence, in both the mutant and wild-type algae, using DNB, produced decay components similar to those seen on opening PSII reaction centres. Such observations indicate that the luminescence hypothesis for the origin of the long-lived lifetime component is not the case.
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Affiliation(s)
- I Moya
- Laboratoire de Photosynthèse, CNRS, 91190, Gif sur Yvette
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van Grondelle R. Excitation energy transfer, trapping and annihilation in photosynthetic systems. ACTA ACUST UNITED AC 1985. [DOI: 10.1016/0304-4173(85)90017-5] [Citation(s) in RCA: 228] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Briantais JM, Vernotte C, Olive J, Wollman FA. Kinetics of cation-induced changes of Photosystem II fluorescence and of lateral distribution of the two photosystems in the thylakoid membranes of pea chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1984. [DOI: 10.1016/0005-2728(84)90210-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Haehnel W, Holzwarth AR, Wendler J. PICOSECOND FLUORESCENCE KINETICS and ENERGY TRANSFER IN THE ANTENNA CHLOROPHYLLS OF GREEN ALGAE. Photochem Photobiol 1983. [DOI: 10.1111/j.1751-1097.1983.tb04497.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Karukstis KK, Sauer K. Fluorescence decay kinetics of chlorophyll in photosynthetic membranes. J Cell Biochem 1983; 23:131-58. [PMID: 6373794 DOI: 10.1002/jcb.240230112] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The absorption of light by the pigments of photosynthetic organisms results in electronic excitation that provides the energy to drive the energy-storing light reactions. A small fraction of this excitation gives rise to fluorescence emission, which serves as a sensitive probe of the energetics and kinetics of the excited states. The wavelength dependence of the excitation and emission spectra can be used to characterize the nature of the absorbing and fluorescing molecules and to monitor the process of sensitization of the excitation transfer from one pigment to another. This excitation transfer process can also be followed by the progressive depolarization of the emitted radiation. Using time-resolved fluorescence rise and decay kinetics, measurements of these processes can now be characterized to as short as a few picoseconds. Typically, excitation transfer among the antenna or light harvesting pigments occurs within 100 psec, whereupon the excitation has reached a photosynthetic reaction center capable of initiating electron transport. When this trap is functional and capable of charge separation, the fluorescence intensity is quenched and only rapidly decaying kinetic components resulting from the loss of excitation in transit in the antenna pigment bed are observed. When the reaction centers are blocked or saturated by high light intensities, the photochemical quenching is relieved, the fluorescence intensity rises severalfold, and an additional slower decay component appears and eventually dominates the decay kinetics. This slower (1-2 nsec) decay results from initial charge separation followed by recombination in the blocked reaction centers and repopulation of the excited electronic state, leading to a rapid delayed fluorescence component that is the origin of variable fluorescence. Recent growth in the literature in this area is reviewed here, with an emphasis on new information obtained on excitation transfer, trapping, and communication between different portions of the photosynthetic membranes.
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Bose S. CHLOROPHYLL FLUORESCENCE IN GREEN PLANTS AND ENERGY TRANSFER PATHWAYS IN PHOTOSYNTHESIS. Photochem Photobiol 1982. [DOI: 10.1111/j.1751-1097.1982.tb09496.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Picosecond fluorescence kinetics in spinach chloroplasts at room temperature. Effects of Mg2+. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1982. [DOI: 10.1016/0005-2728(82)90056-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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17
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Picosecond fluorescence kinetics and energy transfer in chloroplasts and algae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1982. [DOI: 10.1016/0005-2728(82)90007-x] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Chow WS, Ford RC, Barber J. Possible effects of the detachment of stromal lamellae from granal stacks on salt-induced changes in spillover. A study by sonication of chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 635:317-26. [PMID: 7236666 DOI: 10.1016/0005-2728(81)90030-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Salt-induced chlorophyll fluorescence and spillover changes in control and briefly sonicated chloroplasts have been studied under conditions where Photosystem II traps are closed. In a low-salt medium containing 10 mM KCl, control envelope-free chloroplasts exhibited good spillover, as measured by low chlorophyll fluorescence yield at room temperature, a high ratio of the fluorescence peaks F735/F685 at 77 K, and increased Photosystem I activity in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea and Photosystem II light. In contrast, when stacked chloroplasts were briefly sonicated and subsequently diluted into a low-salt medium, a high fluorescence yield at room temperature and a low ratio of F735/F685 at 77 K persisted. When unstacked chloroplasts were sonicated and then diluted into a high-salt medium, the room temperature fluorescence yield remained low. The results are interpreted in terms of a model relating the changes in chlorophyll fluorescence with the lateral diffusion of Photosystem I and Photosystem II chlorophyll-protein complexes in the plane of the thylakoid membrane creating randomized or segregated domains, depending on the degree of electrostatic screening of surface charges (Barber, J. (1980) FEBS Lett. 188, 1-10). It is argued that brief sonication of stacked chloroplasts separates stromal membranes from granal stacks, thus limiting the inter-mixing of the photosystems via lateral diffusion even when the ionic composition of the medium is varied. Consequently energy transfer from Photosystem II to Photosystem I is relatively poor and chlorophyll fluorescence from Photosystem II is enhanced. The loss of the salt effect on sonicated unstacked membranes can also be accommodated by the model. In this case it seems that the generation of small membrane fragments does not allow the normal salt-induced phase separation of the pigment-protein complexes to occur.
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Wong D, ovindjee G. ACTION SPECTRA OF CATION EFFECTS ON THE FLUORESCENCE POLARIZATION AND INTENSITY IN THYLAKOIDS AT ROOM TEMPERATURE. Photochem Photobiol 1981. [DOI: 10.1111/j.1751-1097.1981.tb04304.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Breton J, Geacintov NE. Picosecond fluorescence kinetics and fast energy transfer processes in photosynthetic membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 594:1-32. [PMID: 7006696 DOI: 10.1016/0304-4173(80)90011-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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22
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Searle GF, Tredwell CJ, Barber J, Porter G. Picosecond time-resolved fluorescence study of chlorophyll organisation and excitation energy distribution in chloroplasts from wild-type barley and a mutant lacking chlorophyll b. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 545:496-507. [PMID: 427141 DOI: 10.1016/0005-2728(79)90158-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Picosecond time-resolved fluorescence spectroscopy has been used to investigate the fluorescence emission from wild-type barley chloroplasts and from chloroplasts of the barley mutant, chlorina f-2, which lacks the light-harvesting chlorophyll a/b-protein complex. Cation-controlled regulation of the distribution of excitation energy was studied in isolated chloroplasts at the Fo and Fm levels. It was found that: (a) The fluorescence decay curves were distinctly non-exponential, even at low excitation intensities (less than 2 x 10(14) photons . cm(-2). (b) The fluorescence decay curves could, however, be described by a dual exponential decay law. The wild-type barley chloroplasts gave a short-lived fluorescence component of approximately 140 ps and a long-lived component of 600 ps (Fo) or 1300 ps (Fm) in the presence of Mg2+; in comparison, the mutant barley yielded a short-lived fluorescence component of approx. 50 ps and a long-lived component of 194 ps (Fo) and 424 ps (Fm). (c) The absence of the light-harvesting chlorophyll a/b-protein complex in the mutant results in a low fluorescence quantum yield which is unaffected by the cation composition of the medium. (d) The fluorescence yield changes seen in steady-state experiments on closing Photosystem II reaction centres (Fm/Fo) or on the addition of MgCl2 (+Mg2+/-Mg2+) were in overall agreement with those calculated from the time-resolved fluorescence measurements. The results suggest that the short-lived fluorescence component is partly attributable to the chlorophyll a antenna of Photosystem I, and, in part, to those light-harvesting-Photosystem II pigment combinations which are strongly coupled to the Photosystem I antenna chlorophyll. The long-lived fluorescence component can be ascribed to the light-harvesting-Photosystem II pigment combinations not coupled with the antenna of Photosystem I. In the case of the mutant, the two components appear to be the separate emissions from the Photosystem I and Photosystem II antenna chlorophylls.
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Beddard GS, Fleming GR, Porter G, Searle GF, Synowiec JA. The fluorescence decay kinetics of in vivo chlorophyll measured using low intensity excitation. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 545:165-74. [PMID: 758936 DOI: 10.1016/0005-2728(79)90123-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We report fluorescence lifetimes for in vivo chlorophyll a using a time-correlated single-photon counting technique with tunable dye laser excitation. The fluorescence decay of dark-adapted chlorella is almost exponential with a lifetime of 490 ps, which is independent of excitation from 570 nm to 640 nm. Chloroplasts show a two-component decay of 410 ps and approximately 1.4 ns, the proportion of long component depending upon the fluorescence state of the chloroplasts. The fluorescence lifetime of Photosystem I was determined to be 110 ps from measurements on fragments enriched in Photosystem I prepared from chloroplasts with digitonin.
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Campillo AJ, Shapiro SL. PICOSECOND FLUORESCENCE STUDIES OF EXCITON MIGRATION AND ANNIHILATION IN PHOTOSYNTHETIC SYSTEMS. A REVIEW. Photochem Photobiol 1978. [DOI: 10.1111/j.1751-1097.1978.tb07736.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Pellegrino F, YU W, Alfano RR. FLUORESCENCE KINETICS OF SPINACH CHLOROPLASTS MEASURED WITH A PICOSECOND OPTICAL KERR GATE. Photochem Photobiol 1978. [DOI: 10.1111/j.1751-1097.1978.tb07739.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wong D, Jursinic P. ANALYSIS OF MICROSECOND FLUORESCENCE YIELD AND DELAYED LIGHT EMISSION CHANGES AFTER A SINGLE FLASH IN PEA CHLOROPLASTS: EFFECTS OF MONO- AND DIVALENT CATIONS. Photochem Photobiol 1978. [DOI: 10.1111/j.1751-1097.1978.tb07735.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Tredwell CJ, Synowiec JA, Searle GFW, Porter G, Barber J. PICOSECOND TIME RESOLVED FLUORESCENCE OF CHLOROPHYLL IN VIVO. Photochem Photobiol 1978. [DOI: 10.1111/j.1751-1097.1978.tb07740.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Hipkins MF. The emission yields of delayed and prompt fluorescence from chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 502:161-8. [PMID: 76478 DOI: 10.1016/0005-2728(78)90140-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
1. The decay of delayed fluorescence from chloroplasts blocked with 3-(3,4-dichlorophenyl)-1,1-dimethylurea and uncoupled with gramicidin has been measured in the time range 0.75--45 ms by use of a laser phosphoroscope. 2. The decays have been analysed as the sum of three first-order components of approximate half-lives 0.2, 2.5 and 300 ms by a computer-assisted least-squares fit procedure. 3. The prompt fluorescence yield of the chloroplasts was manipulated by changing the cation concentration of the chloroplast-suspending medium. 4. Analysis of the concentration dependence of the components of the delayed fluorescence decay and of the prompt fluorescence inductions indicates that the emission yield of the intermediate (tau approximately 2.5 ms) component of the decay is equal to the fluorescence yield of a Photosystem II photosynthetic unit with an open trap, and that for the slow (tau approximately 300 ms) component the emission yield is equal to the total Photosystem II prompt fluorescence yield. 5. It is concluded that the delayed fluorescence yield in the time range studied is a complex function of time, which may be due to there being different mechanisms leading to delayed fluorescence production at short and long times after cessation of illumination.
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Barber J, Searle GF, Tredwell CJ. Picosecond time-resolved study of MgCl2-induced chlorophyll fluorescence yield changes from chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 501:174-82. [PMID: 620010 DOI: 10.1016/0005-2728(78)90024-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The MgCl2-induced chlorophyll fluorescence yield changes in broken chloroplasts, suspended in a cation-free medium, treated with 3,-(3',4'-dichlorophenyl)-1,1-dimethylurea and pre-illuminated, has been investigated on a pico-second time scale. Chloroplasts in the low fluorescing state showed a fluorescence decay law of the form exp --At1/2, where A was found to be 0.052 ps-1/2, and may be attributed to the rate of spillover from Photosystem II to Photosystem I. Addition of 10 mM MgCl2 produced a 50% increase in the steady-state fluorescence quantum yield and caused a marked decrease in the decay rate. The fluorescence deday law was found to be predominantly exponential with a 1/e lifetime of 1.6 ns. These results support the hypothesis that cation-induced changes in the fluorescence yield of chlorophyll are related to the variations in the rate of energy transfer from Photosystem II to Photosystem I, rather than to changes in the partitioning of absorbed quanta between the two systems.
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Butler WL. Tripartite and bipartite models of the photochemical apparatus of photosynthesis. CIBA FOUNDATION SYMPOSIUM 1978:237-56. [PMID: 256532 DOI: 10.1002/9780470720431.ch13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Tripartite and bipartite models for the photochemical apparatus of photosynthesis are presented and examined. It is shown that the equations for the yields of fluorescence from the different parts of the photochemical apparatus of the tripartite model transform into the simple equations of the bipartite formulation when the probability for energy transfer from the light-harvesting chlorophyll a/b complex to photosystem II is unity. The nature of the 695 and 735 nm fluorescence bands which appear in the emission spectrum of chloroplasts at low temperature is examined. It is proposed that these bands are due to fluorescence from energy-trapping centres which form in the antenna chlorophyll of photosystem II and photosystem I on cooling to low temperature. Even though these fluorescence emissions can be regarded as low temperature artifacts since they are not present at physiological temperatures, they nevertheless are proportional to the excitation energy in the two photosystems and can be used to monitor energy distribution in the photochemical apparatus. However, the question of their artifactual nature is crucial to the interpretation of fluorescence-lifetime measurements at low temperature.
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Beddard GS, Fleming GR, Porter G, Tredwell CJ. Fluorescence and Energy Transfer in Photosynthesis. ACTA ACUST UNITED AC 1978. [DOI: 10.1007/978-3-642-67099-2_30] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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