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Checcucci G, Storti B, Ghetti F, Signore G, Bizzarri R. Fluorescence lifetime microscopy reveals the biologically-related photophysical heterogeneity of oxyblepharismin in light-adapted (blue) Blepharisma japonicum cells. Photochem Photobiol Sci 2017. [PMID: 28636018 DOI: 10.1039/c7pp00072c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The step-up photophobic response of the heterotrich ciliate Blepharisma japonicum is mediated by a hypericinic pigment, blepharismin, which is not present in any of the known six families of photoreceptors, namely rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins, and BLUF proteins. Upon irradiation, native cells become light-adapted (blue) by converting blepharismin into the photochemically stable oxyblepharismin (OxyBP). So far, OxyBP has been investigated mainly from a photophysical point of view in vitro, either alone or complexed with proteins. In this work, we exploit the vivid fluorescence of OxyBP to characterize its lifetime emission in blue B. Japonicum cells, on account of the recognized role of the fluorescence lifetime to provide physicochemical insights into the fluorophore environment at the nanoscale. In a biological context, OxyBP modifies its emission lifetime as compared to isotropic media. The phasor approach to fluorescence lifetime microscopy in confocal mode highlights that fluorescence originates from two excited states, whose relative balance changes throughout the cell body. Additionally, Cilia and kinetids, i.e., the organelles involved in photomovement, display lifetime asymmetry between the anterior and posterior part of the cell. From these data, some hypotheses on the phototransduction mechanism are proposed.
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Affiliation(s)
- G Checcucci
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, I-56127 Pisa, Italy.
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Buonanno F, Quassinti L, Bramucci M, Amantini C, Lucciarini R, Santoni G, Iio H, Ortenzi C. The protozoan toxin climacostol inhibits growth and induces apoptosis of human tumor cell lines. Chem Biol Interact 2008; 176:151-64. [DOI: 10.1016/j.cbi.2008.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 07/21/2008] [Accepted: 07/21/2008] [Indexed: 10/21/2022]
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Youssef T, Brazard J, Ley C, Lacombat F, Plaza P, Martin MM, Sgarbossa A, Checcucci G, Lenci F. Steady-state and femtosecond photoinduced processes of blepharismins bound to alpha-crystallin. Photochem Photobiol Sci 2008; 7:844-53. [DOI: 10.1039/b800848e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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5
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Podestà A, Gioffré D, Grossi T, Montagnoli G. Immunological and Biochemical Evidence that Blepharismin is not a Prosthetic Group. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2000)0710669iabetb2.0.co2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Mahet M, Plaza P, Martin M, Checcucci G, Lenci F. Primary photoprocesses in oxyblepharismin interacting with its native protein partner. J Photochem Photobiol A Chem 2007. [DOI: 10.1016/j.jphotochem.2006.06.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Colombetti G, Checcucci G, Lucia S, Usai C, Ramoino P, Bianchini P, Pesce M, Vicidomini G, Diaspro A. Evidence for ciliary pigment localization in colored ciliates and implications for their photosensory transduction chain: A confocal microscopy study. Microsc Res Tech 2007; 70:1028-33. [PMID: 17661390 DOI: 10.1002/jemt.20508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this study we report for the first time the localization of a photoreceptor pigment in the cilia of the colored heterotrich ciliates Blepharisma japonicum red and blue form, Fabrea salina, and Stentor coeruleus, as result of a confocal microscopy investigation. Optical sectioning confocal microscopy has been used for studying the spatial distribution of the pigment in the cell body, surprisingly showing that, besides its expected presence in the cortical region immediately below the cell membrane, it is located in the cilia too. In order to ascertain possible differences in the pigment fluorescence properties along the cell body, we have measured emission spectra from different parts of it (anterior, posterior, and cilia). Our results clearly indicate that in all cases the spectra are the same, within experimental errors. Finally, we have evaluated the pigment relative fluorescence efficiency of these ciliates. In an ordered scale from lower to greater efficiency, we have S. coeruleus, B. japonicum blue, B. japonicum red, and F. salina. The possible implications of our findings for the process of photosensory transduction are discussed.
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Sobierajska K, Fabczak H, Fabczak S. Photosensory transduction in unicellular eukaryotes: A comparison between related ciliates Blepharisma japonicum and Stentor coeruleus and photoreceptor cells of higher organisms. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2006; 83:163-71. [PMID: 16488618 DOI: 10.1016/j.jphotobiol.2006.01.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 12/29/2005] [Accepted: 01/07/2006] [Indexed: 11/27/2022]
Abstract
Blepharisma japonicum and Stentor coeruleus are related ciliates, conspicuous by their photosensitivity. They are capable of avoiding illuminated areas in the surrounding medium, gathering exclusively in most shaded places (photodispersal). Such behaviour results mainly from motile photophobic response occurring in ciliates. This light-avoiding response is observed during a relatively rapid increase in illumination intensity (light stimulus) and consists of cessation of cell movement, a period of backward movement (ciliary reversal), followed by a forward swimming, usually in a new direction. The photosensitivity of ciliates is ascribed to their photoreceptor system, composed of pigment granules, containing the endogenous photoreceptor -- blepharismin in Blepharisma japonicum, and stentorin in Stentor coeruleus. A light stimulus, applied to both ciliates activates specific stimulus transduction processes leading to the electrical changes at the plasma membrane, correlated with a ciliary reversal during photophobic response. These data indicate that both ciliates Blepharisma japonicum and Stentor coeruleus, the lower eukaryotes, are capable of transducing the perceived light stimuli in a manner taking place in some photoreceptor cells of higher eukaryotes. Similarities and differences concerning particular stages of light transduction in eukaryotes at different evolutional levels are discussed in this article.
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Affiliation(s)
- Katarzyna Sobierajska
- Department of Cell Biology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3, Pasteur Street, PL 02-093 Warsaw, Poland
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Pieroni O, Plaza P, Mahet M, Angelini N, Checcucci G, Malatesta M, Martin MM, Lenci F. Circular Dichroism of the Photoreceptor Pigment Oxyblepharismin. Photochem Photobiol 2005; 81:1343-6. [PMID: 15901211 DOI: 10.1562/2005-04-28-rn-504] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Circular dichroism (CD) was used to study the structure of oxyblepharismin (OxyBP), the photoreceptor chromophore for the photophobic response of the blue form of Blepharisma japonicum. Both the chromophore associated to its native protein and the free chromophore in ethanol solution were investigated. CD spectra in the far-UV range indicate that OxyBP induces a slight increase in the alpha-helix content of the protein matrix. CD spectra in the near-UV and visible region of the spectrum show that OxyBP adopts a chiral conformation with a preferential geometry not only when associated to its protein matrix, but also when isolated and dissolved in ethanol. This experimental result is related to the existence of a high-energy interconversion barrier between two enantiomeric structures of the molecule and discussed on the basis of an asymmetric biosynthesis of its precursor, blepharismin.
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Affiliation(s)
- Osvaldo Pieroni
- Istituto di Biofisica CNR-Sezione di Pisa, 56124 Pisa, Italy.
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Plaza P, Mahet M, Martin MM, Angelini N, Malatesta M, Checcucci G, Lenci F. Spectroscopic study of the chromophore–protein association and primary photoinduced events in the photoreceptor of Blepharisma japonicum. Photochem Photobiol Sci 2005; 4:754-61. [PMID: 16121288 DOI: 10.1039/b417086e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Blepharisma japonicum is a ciliated protozoan exhibiting a strong step-up photophobic response upon illumination. The photoreceptor chromophores responsible for this response have been identified to be hypericin-like chromophores (blepharismin and oxyblepharismin), complexed to a 200 kDa non-water-soluble protein. The present work opens up new perspectives on the primary phototransduction steps of B. japonicum's light perception through a joined approach by steady-state fluorescence spectroscopy, time-resolved fluorescence anisotropy and sub-picosecond transient absorption spectroscopy. The free chromophore of the light-adapted form of the cell (oxyblepharismin) was studied in various solvents and its spectroscopic properties, as well as its primary excited-state reactivity, compared with those of the corresponding pigment-protein complex, extracted by phosphate-concentration-step chromatography on a hydroxyapatite column. Fluorescence anisotropy together with SDS PAGE electrophoresis results confirm that oxyblepharismin is non-covalently bound to the apoprotein and show that, in the excited state, it is free to rotate in all directions within the binding site where it experiences a large local viscosity. Time-resolved anisotropy measurements on aromatic amino acids confirm that the molecular weight of the protein is of the order of 200 kDa. Although showing very similar steady-state spectra, free oxyblepharismin and its protein complex have noticeably different excited-state behaviours. In particular, the protein complex exhibits a pronounced short-lived absorption feature in the 640--750 nm range, decaying biexponentially in 4 ps and 56 ps. Those decays, also observed in other spectral regions, are not found in the corresponding kinetics of the isolated pigment in solution. This early behaviour of the protein complex might be the signature of the primary phototransduction process, possibly involving an electron transfer from the pigment to a neighbouring protein acceptor residue as it had been suggested in previous studies.
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Affiliation(s)
- Pascal Plaza
- UMR 8640 CNRS, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France.
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Buonanno F. Variations in the efficiency of ciliate extrusomal toxins against a common ciliate predator, the catenulidStenostomum Sphagnetorum. ACTA ACUST UNITED AC 2005. [DOI: 10.1080/11250000509356688] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Sgarbossa A, Checcucci G, Lenci F. Photoreception and photomovements of microorganisms. Photochem Photobiol Sci 2002; 1:459-67. [PMID: 12659155 DOI: 10.1039/b110629e] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many freely motile microorganisms can perceive and transduce external photic stimuli to the motor apparatus, eventually moving, by means of various behavioural strategies, into environments in which the illumination conditions are the most favourable for their life. In different microorganisms, a wide range of chromophores operate as light detectors, each of them set in a special molecular pocket that, in its turn, can be linked to another component of the transduction chain. The diverse photosensors are organized in special (and in many cases dedicated) photoreceptor units or subcellular organelles. The main molecular mechanisms connecting the early event of photon absorption to the formation of the signalling state down to the dark steps of the transduction chain are discussed in a selected number of case examples. The possible importance of an intensive multidisciplinary approach to these problems in an evolutionary perspective is finally briefly outlined.
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Podestà A, Gioffré D, Grossi T, Montagnoli G. Immunological and biochemical evidence that blepharismin is not a prosthetic group. Photochem Photobiol 2000; 71:669-73. [PMID: 10818800 DOI: 10.1562/0031-8655(2000)071<0669:iabetb>2.0.co;2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A polyclonal, multispecific antiserum was raised against a whole 3[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate-extract of nonirradiated Blepharisma japonicum cells. It was used to reveal the composition of solutions that were hypothesized to contain the photoreceptor of the ciliate. A Bio-Gel A 1.5 m fine column chromatography of the extract allowed recovery of a single elution peak isolated by recording the 580 nm light absorbance. Fused-rocket immunoelectrophoresis of this material revealed a large number of > 300 kDa coeluted proteins. Blepharismin-rich material with a molecular mass of approximately 50 kDa, consisting of at least nine proteins was obtained when the same extract underwent preparative isoelectric focusing before column chromatography separation. Purification of the pigment obtained from light-exposed cells gave blepharismin-rich material with a molecular weight of approximately 200 kDa. Comparison of the materials obtained under the same conditions, either from the dark-kept or light-irradiated cells, by means of pore-gradient electrophoresis confirmed that proteins present in the two preparations were different. It revealed only a very small amount, if any, of proteins in the chromatography fractions with the highest absorbance at 600 nm. Results are discussed on the basis of the hypothesis that a specific blepharismin-binding protein does not exist in the protozoan.
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Affiliation(s)
- A Podestà
- Department of Veterinary Anatomy, Biochemistry and Physiology, University of Pisa, Italy.
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Fabczak H. Contribution of phosphoinositide-dependent signalling to photomotility of Blepharisma ciliate. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2000; 55:120-7. [PMID: 10942076 DOI: 10.1016/s1011-1344(00)00031-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The effect of experimental procedures designed to modify an intracellular phosphoinositide signalling pathway, which may be instrumental in the photophobic response of the protozoan ciliate Blepharisma japonicum, has been investigated. To assess this issue, the latency time of the photophobic response and the cell photoresponsiveness have been assayed employing newly developed computerized videorecording and standard macro-photographic methods. Cell incubation with neomycin, heparin and Li+, drugs known to greatly impede phosphoinositide turnover, causes evident dose-dependent changes in cell photomotile behaviour. The strongest effect on photoresponses is exerted by neomycin, a potent inhibitor of polyphosphoinositide hydrolysis. The presence of micromolar concentrations of neomycin in the cell medium causes both prolongation of response latency and decrease of cell photoresponsiveness. Neomycin at higher concentrations (> 10 microM) abolishes the cell response to light at the highest applied intensity. A slightly lower inhibition of cell responsiveness to light stimulation and prolongation of response latency are observed in cells incubated in the presence of heparin, an inositol trisphosphate receptor antagonist. Lithium ions, widely known to deplete the intracellular phosphoinositide pathway intermediate, inositol trisphosphate, added to the cell medium at millimolar level, also cause a slowly developing inhibitory effect on cell photoresponses. Mastoparan, a specific G-protein activator, efficiently mimics the effect of light stimulation. In dark-adapted ciliates, it elicits ciliary reversal with the response latency typical for ciliary reversal during the photophobic response. Sustained treatment of Blepharisma cells with mastoparan also suppresses the photoresponsiveness, as in the case of cell adaptation to light during prolonged illumination. The mastoparan-induced responses can be eliminated by pretreatment of the cells with neomycin. Moreover, using antibodies raised against bovine transducin, a cross-reacting protein with an apparent molecular mass of about 55 kDa in the Blepharisma cortex fraction is detected on immunoblots. The obtained results indirectly suggest that the changes in internal inositol trisphosphate level, possibly elicited by G-protein-coupled phospholipase C, might play a role in the photophobic response of Blepharisma. However, further experiments are necessary to clarify the possible coupling between the G-protein and the putative phospholipase C.
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Affiliation(s)
- H Fabczak
- Nencki Institute of Experimental Biology, Department of Cell Biology, Warsaw, Poland.
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Checcucci G, Sgarbossa A, Gioffré D, Lenci F, Ghetti F. Action Spectra for UVB Impacts on Blepharisma japonicum Motility and Photobehavior. Photochem Photobiol 1999. [DOI: 10.1111/j.1751-1097.1999.tb05310.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Harumoto T, Miyake A, Ishikawa N, Sugibayashi R, Zenfuku K, lio H. Chemical defense by means of pigmented extrusomes in the ciliate Blepharisma japonicum. Eur J Protistol 1998. [DOI: 10.1016/s0932-4739(98)80014-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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18
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Angelini N, Quaranta A, Checcucci G, Song PS, Lenci F. Electron Transfer Fluorescence Quenching of Blepharisma japonicum Photoreceptor Pigments. Photochem Photobiol 1998. [DOI: 10.1111/j.1751-1097.1998.tb05297.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lenci F, Checcucci G, Ghetti F, Gioffrè D, Sgarbossa A. Sensory perception and transduction of UV-B radiation by the ciliate Blepharisma japonicum. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1336:23-7. [PMID: 9271246 DOI: 10.1016/s0304-4165(97)00005-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A key question to answer studying the biological effects of ultraviolet radiation on planktonic micro-organisms is whether they can perceive UV-B radiation as a sensory signal, likewise they do with visible light. We have faced this problem performing an individual-cell analysis of Blepharisma japonicum photomotile responses to UV-B stimuli. Our results on spectral responsiveness and on the effects of a photoresponse inhibitor indicate that B. japonicum is capable to perceive and transduce UV-B radiation as an environmental sensory stimulus, which it escapes from gathering in shadowed areas. Similar UV-B avoidance motile reactions could serve as a behavioural defence mechanism contributing to avoid harmful overexposure to UV-B.
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Affiliation(s)
- F Lenci
- CNR Istituto di Biofisica, Pisa, Italy.
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Checcucci G, Shoemaker RS, Bini E, Cerny R, Tao N, Hyon JS, Gioffre D, Ghetti F, Lenci F, Song PS. Chemical Structure of Blepharismin, the Photosensor Pigment for Blepharisma japonicum. J Am Chem Soc 1997. [DOI: 10.1021/ja970713q] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Giovanni Checcucci
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Richard S. Shoemaker
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Elisabetta Bini
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Ronald Cerny
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Nengbing Tao
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Jae-Seok Hyon
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Domenico Gioffre
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Francesco Ghetti
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Francesco Lenci
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
| | - Pill-Soon Song
- CNR Institute of Biophysics, Pisa, Italy Department of Chemistry, University of Nebraska Lincoln, Nebraska 68588-0304 Kumho Life & Environmental Science Laboratory Kwangju 506-712, Korea
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Matsuoka T, Sato M, Maeda M, Naoki H, Tanaka T, Kotsuki H. Localization of Blepharismin Photosensors and Identification of a Photoreceptor Complex Mediating the Step-up Photophobic Response of the Unicellular Organism, Blepharisma. Photochem Photobiol 1997. [DOI: 10.1111/j.1751-1097.1997.tb01943.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wells TA, Losi A, Dai R, Scott P, Park SM, Golbeck J, Song PS. Electron Transfer Quenching and Photoinduced EPR of Hypericin and the Ciliate Photoreceptor Stentorin. J Phys Chem A 1997. [DOI: 10.1021/jp9612588] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Todd A. Wells
- Departments of Chemistry and Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
| | - Aba Losi
- Departments of Chemistry and Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
| | - Renke Dai
- Departments of Chemistry and Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
| | - Paul Scott
- Departments of Chemistry and Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
| | - Su-Moon Park
- Departments of Chemistry and Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
| | - John Golbeck
- Departments of Chemistry and Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
| | - Pill-Soon Song
- Departments of Chemistry and Biochemistry, University of Nebraska, Lincoln, Nebraska 68588-0304
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Angelini N, Cubeddu R, Ghetti F, Lenci F, Taroni P, Valentini G. In vivo spectroscopic study of photoreceptor pigments of Blepharisma japonicum red and blue cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1995. [DOI: 10.1016/0005-2728(95)00080-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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24
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Lenci F, Angelini N, Ghetti F, Sgarbossa A, Losi A, Vecli A, Viappiani C, Taroni P, Pifferi A, Cubeddu R. Spectroscopic and photoacoustic studies of hypericin embedded in liposomes as a photoreceptor model. Photochem Photobiol 1995; 62:199-204. [PMID: 7638267 DOI: 10.1111/j.1751-1097.1995.tb05259.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In photoresponsive ciliates, like Blepharisma japonicum and Stentor coeruleus, the photoreceptor pigments responsible for photomotile reactions are hypericin-type chromophores packed in highly osmiophilic subpellicular granules. Lipopsomes loaded with hypericin can constitute a simple model system, appropriate for understanding the primary light-induced molecular events triggering the sensory chain in these microorganisms. Optical absorption, steady-state and time-resolved fluorescence and pulsed photoacoustic calorimetry have been used to measure spectral distributions, fluorescence lifetimes, radiative and radiationless transition quantum yields of hypericin when assembled into egg L-alpha-phosphatidylcholine liposomes. With respect to hypericin ethanol solutions, both absorption and fluorescence maxima are 5 nm red shifted when the pigment is inserted into the lipidic microenvironment, regardless of the hypericin local concentration. Increasing by 100 times the hypericin local concentration decreases the relative fluorescence quantum yield by a factor of around 150 and the fraction of thermally released energy, conversely, increases from 0.6 to 0.9. From the analysis of fluorescence lifetimes and their relative amplitudes it appears that a subnanosecond living component is predominant at the highest hypericin local concentrations.
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Affiliation(s)
- F Lenci
- Istituto Biofisica CNR, Pisa, Italy
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Effects of UV-B irradiation on motility and photoresponsiveness of the coloured ciliate Blepharisma japonicum. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 1995. [DOI: 10.1016/1011-1344(94)07070-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Matsuoka T, Tsuda T, Ishida M, Kato Y, Takayanagi M, Fujino T, Mizuta S. PRESUMED PHOTORECEPTOR PROTEIN AND ULTRASTRUCI'URE OF THE PHOTORECEPTOR ORGANELLE IN THE CILIATED PROTOZOAN, Blepharisma. Photochem Photobiol 1994. [DOI: 10.1111/j.1751-1097.1994.tb05155.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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