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Tanno A, Tokutsu R, Arakaki Y, Ueki N, Minagawa J, Yoshimura K, Hisabori T, Nozaki H, Wakabayashi KI. The four-celled Volvocales green alga Tetrabaena socialis exhibits weak photobehavior and high-photoprotection ability. PLoS One 2021; 16:e0259138. [PMID: 34699573 PMCID: PMC8547699 DOI: 10.1371/journal.pone.0259138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 10/13/2021] [Indexed: 11/28/2022] Open
Abstract
Photo-induced behavioral responses (photobehaviors) are crucial to the survival of motile phototrophic organisms in changing light conditions. Volvocine green algae are excellent model organisms for studying the regulatory mechanisms of photobehavior. We recently reported that unicellular Chlamydomonas reinhardtii and multicellular Volvox rousseletii exhibit similar photobehaviors, such as phototactic and photoshock responses, via different ciliary regulations. To clarify how the regulatory systems have changed during the evolution of multicellularity, we investigated the photobehaviors of four-celled Tetrabaena socialis. Surprisingly, unlike C. reinhardtii and V. rousseletii, T. socialis did not exhibit immediate photobehaviors after light illumination. Electrophysiological analysis revealed that the T. socialis eyespot does not function as a photoreceptor. Instead, T. socialis exhibited slow accumulation toward the light source in a photosynthesis-dependent manner. Our assessment of photosynthetic activities showed that T. socialis chloroplasts possess higher photoprotection abilities against strong light than C. reinhardtii. These data suggest that C. reinhardtii and T. socialis employ different strategies to avoid high-light stress (moving away rapidly and gaining photoprotection, respectively) despite their close phylogenetic relationship.
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Affiliation(s)
- Asuka Tanno
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Ryutaro Tokutsu
- Division of Environmental Photobiology, National Institute for Basic Biology, Okazaki, Japan
- Faculty of Life Science, Department of Basic Biology, The Graduate University for Advanced Studies, SOKENDAI, Okazaki, Japan
| | - Yoko Arakaki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Noriko Ueki
- Science Research Center, Hosei University, Tokyo, Japan
| | - Jun Minagawa
- Division of Environmental Photobiology, National Institute for Basic Biology, Okazaki, Japan
- Faculty of Life Science, Department of Basic Biology, The Graduate University for Advanced Studies, SOKENDAI, Okazaki, Japan
| | - Kenjiro Yoshimura
- Department of Machinery and Control Systems, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, Japan
| | - Toru Hisabori
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Hisayoshi Nozaki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Japan
| | - Ken-ichi Wakabayashi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
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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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Main photophysical properties of oxyblepharismin. Biophys Chem 2017; 229:5-10. [DOI: 10.1016/j.bpc.2017.05.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 05/19/2017] [Accepted: 05/19/2017] [Indexed: 11/22/2022]
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Ozasa K, Lee J, Song S, Maeda M. Transient freezing behavior in photophobic responses of Euglena gracilis investigated in a microfluidic device. PLANT & CELL PHYSIOLOGY 2014; 55:1704-1712. [PMID: 25074906 DOI: 10.1093/pcp/pcu101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We found that the transient freezing behavior in photophobic responses of Euglena gracilis is a good indicator of the metabolic status of the cells. The transient blue light photophobic responses of E. gracilis cells were investigated on-chip using a new measurement, 'trace momentum' (TM), to evaluate their swimming activity quantitatively in real time. When blue light of intensity >30 mW cm(-2) was repeatedly switched on and off, a large negative spike in the TM was observed at the onset of the 'blue-light-off' phase. Single-cell trace analysis at a blue light intensity of 40 mW cm(-2) showed that 48% (on average, n = 15) of tumbling Euglena cells ceased activity ('freezing') for 2-30 s at the onset of blue-light-off before commencing forward motion in a straight line (termed 'straightforward swimming'), while 45% smoothly commenced straightforward swimming without delay. The proportion of freezing Euglena cells depended on the blue light intensity (only 20% at 20 mW cm(-2)). When the cells were stimulated by four blue light pulses at the higher intensity, without pre-exposure, the transient freezing behavior was more prominent but, on repeating the stimuli after an 80 min interval in red light, the same cells did not freeze. This shows that the metabolism of the cells had changed to anti-freezing during the interval. The relationship between the interval time with/without light irradiation and the blue light adaptation was elucidated experimentally. The origin of the freezing behavior is considered to be a shortage of a metabolic substance that promotes smooth switching of flagellum movement from in situ rotation mode to a straightforward swimming mode.
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Affiliation(s)
- Kazunari Ozasa
- Bioengineering Lab., RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan
| | - Jeesoo Lee
- Department of Mechanical Convergence Engineering, Hanyang University, 17 Haendang-dong, Seongdong-gu, Seoul, 133-791, Korea
| | - Simon Song
- Department of Mechanical Convergence Engineering, Hanyang University, 17 Haendang-dong, Seongdong-gu, Seoul, 133-791, Korea
| | - Mizuo Maeda
- Bioengineering Lab., RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan
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Abstract
Ultraviolet (UV) radiation can cause stresses or act as a photoregulatory signal depending on its wavelengths and fluence rates. Although the most harmful effects of UV on living cells are generally attributed to UV-B radiation, UV-A radiation can also affect many aspects of cellular processes. In cyanobacteria, most studies have concentrated on the damaging effect of UV and defense mechanisms to withstand UV stress. However, little is known about the activation mechanism of signaling components or their pathways which are implicated in the process following UV irradiation. Motile cyanobacteria use a very precise negative phototaxis signaling system to move away from high levels of solar radiation, which is an effective escape mechanism to avoid the detrimental effects of UV radiation. Recently, two different UV-A-induced signaling systems for regulating cyanobacterial phototaxis were characterized at the photophysiological and molecular levels. Here, we review the current understanding of the UV-A mediated signaling pathways in the context of the UV-A perception mechanism, early signaling components, and negative phototactic responses. In addition, increasing evidences supporting a role of pterins in response to UV radiation are discussed. We outline the effect of UV-induced cell damage, associated signaling molecules, and programmed cell death under UV-mediated oxidative stress.
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Bléger D, Liebig T, Thiermann R, Maskos M, Rabe JP, Hecht S. Light-Orchestrated Macromolecular “Accordions”: Reversible Photoinduced Shrinking of Rigid-Rod Polymers. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201106879] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Bléger D, Liebig T, Thiermann R, Maskos M, Rabe JP, Hecht S. Light-Orchestrated Macromolecular “Accordions”: Reversible Photoinduced Shrinking of Rigid-Rod Polymers. Angew Chem Int Ed Engl 2011; 50:12559-63. [DOI: 10.1002/anie.201106879] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Indexed: 11/07/2022]
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Gromov EV, Burghardt I, Köppel H, Cederbaum LS. Photoinduced Isomerization of the Photoactive Yellow Protein (PYP) Chromophore: Interplay of Two Torsions, a HOOP Mode and Hydrogen Bonding. J Phys Chem A 2011; 115:9237-48. [DOI: 10.1021/jp2011843] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Evgeniy V. Gromov
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
- Laboratory of Quantum Chemistry, Computer Center, Irkutsk State University, K. Marks 1, 664003 Irkutsk, Russian Federation
| | - Irene Burghardt
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, D−60438 Frankfurt/Main, Germany
| | - Horst Köppel
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
| | - Lorenz S. Cederbaum
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany
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Bléger D, Yu Z, Hecht S. Toward optomechanics: Maximizing the photodeformation of individual molecules. Chem Commun (Camb) 2011; 47:12260-6. [DOI: 10.1039/c1cc15180k] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Brazard J, Ley C, Lacombat F, Plaza P, Martin MM, Checcucci G, Lenci F. Primary Photoprocesses Involved in the Sensory Protein for the Photophobic Response of Blepharisma japonicum. J Phys Chem B 2008; 112:15182-94. [DOI: 10.1021/jp805815e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Johanna Brazard
- UMR 8640 CNRS-ENS-UPMC, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France, and Istituto di Biofisica del CNR, Via G. Moruzzi 1, 56100 Pisa, Italy
| | - Christian Ley
- UMR 8640 CNRS-ENS-UPMC, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France, and Istituto di Biofisica del CNR, Via G. Moruzzi 1, 56100 Pisa, Italy
| | - Fabien Lacombat
- UMR 8640 CNRS-ENS-UPMC, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France, and Istituto di Biofisica del CNR, Via G. Moruzzi 1, 56100 Pisa, Italy
| | - Pascal Plaza
- UMR 8640 CNRS-ENS-UPMC, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France, and Istituto di Biofisica del CNR, Via G. Moruzzi 1, 56100 Pisa, Italy
| | - Monique M. Martin
- UMR 8640 CNRS-ENS-UPMC, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France, and Istituto di Biofisica del CNR, Via G. Moruzzi 1, 56100 Pisa, Italy
| | - Giovanni Checcucci
- UMR 8640 CNRS-ENS-UPMC, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France, and Istituto di Biofisica del CNR, Via G. Moruzzi 1, 56100 Pisa, Italy
| | - Francesco Lenci
- UMR 8640 CNRS-ENS-UPMC, Département de Chimie, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France, and Istituto di Biofisica del CNR, Via G. Moruzzi 1, 56100 Pisa, Italy
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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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Fabczak H, Sobierajska K, Fabczak S. A rhodopsin immunoanalog in the related photosensitive protozoans Blepharisma japonicum and Stentor coeruleus. Photochem Photobiol Sci 2008; 7:1041-5. [DOI: 10.1039/b717280j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lobban CS, Hallam SJ, Mukherjee P, Petrich JW. Photophysics and Multifunctionality of Hypericin-Like Pigments in Heterotrich Ciliates: A Phylogenetic Perspective. Photochem Photobiol 2007; 83:1074-94. [PMID: 17880503 DOI: 10.1111/j.1751-1097.2007.00191.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper, we review the literature and present some new data to examine the occurrence and photophysics of the diverse hypericin-like chromophores in heterotrichs, the photoresponses of the cells, the various roles of the pigments and the taxa that might be studied to advance our understanding of these pigments. Hypericin-like chromophores are known chemically and spectrally so far only from the stentorids and Fabrea, the latter now seen to be sister to stentorids in the phylogenetic tree. For three hypericin-like pigments, the structures are known but these probably do not account for all the colors seen in stentorids. At least eight physiological groups of Stentor exist depending on pigment color and presence/absence of zoochlorellae, and some species can be bleached, leading to many opportunities for comparison of pigment chemistry and cell behavior. Several different responses to light are exhibited among heterotrichs, sometimes by the same cell; in particular, cells with algal symbionts are photophilic in contrast to the well-studied sciaphilous (shade-loving) species. Hypericin-like pigments are involved in some well-known photophobic reactions but other pigments (rhodopsin and flavins) are also involved in photoresponses in heterotrichs and other protists. The best characterized role of hypericin-like pigments in heterotrichs is in photoresponses and they have at least twice evolved a role as photoreceptors. However, hypericin and hypericin-like pigments in diverse organisms more commonly serve as predator defense and the pigments are multifunctional in heterotrichs. A direct role for the pigments in UV protection is possible but evidence is equivocal. New observations are presented on a folliculinid from deep water, including physical characterization of its hypericin-like pigment and its phylogenetic position based on SSU rRNA sequences. The photophysics of hypericin and hypericin-like pigments is reviewed. Particular attention is given to how their excited-state properties are modified by the environment. Dramatic changes in excited-state behavior are observed as hypericin is moved from the homogeneous environment of organic solvents to the much more structured surroundings provided by the complexes it forms with proteins. Among these complexes, it is useful to consider the differences between environments where hypericin is not found naturally and those where it is, notably, for example, in heterotrichs. It is clear that interaction with a protein modifies the photophysics of hypericin and understanding the molecular basis of this interaction is one of the outstanding problems in elucidating the function of hypericin and hypericin-like chromophores.
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Mukherjee P, Fulton DB, Halder M, Han X, Armstrong DW, Petrich JW, Lobban CS. Maristentorin, a novel pigment from the positively phototactic marine ciliate Maristentor dinoferus, is structurally related to hypericin and stentorin. J Phys Chem B 2007; 110:6359-64. [PMID: 16553454 DOI: 10.1021/jp055871f] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photoreceptor pigment of the heterotrich ciliate, Maristentor dinoferus, has been characterized. It is structurally similar to those of Stentor coeruleus and Blepharisma japonicum but differs significantly in that it bears no aromatic hydrogens. The structure of the pigment, maristentorin, is based upon the hypericin skeleton, and its spectra are nearly identical to those of hypericin but shifted toward the red. Within experimental error, its fluorescence lifetime is identical to that of hypericin, approximately 5.5 ns in dimethylsulfoxide. It is remarkable that while the pigments are structurally similar in S. coeruleus and M. dinoferus, in the former there is an abrupt photophobic response, whereas in the latter there is a slow response toward light. The roles of the hypericin-like pigments in the heterotrich ciliates are discussed as potentially analogous in Maristentor.
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Affiliation(s)
- Prasun Mukherjee
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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Gromov EV, Burghardt I, Köppel H, Cederbaum LS. Electronic Structure of the PYP Chromophore in Its Native Protein Environment. J Am Chem Soc 2007; 129:6798-806. [PMID: 17474743 DOI: 10.1021/ja069185l] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report on supermolecular ab initio calculations which clarify the role of the local amino acid environment in determining the unique electronic structure properties of the photoactive yellow protein (PYP) chromophore. The extensive ab initio calculations, at the level of the CC2 and EOM-CCSD methods, allow us to explicitly address how the interactions between the deprotonated p-coumaric thio-methyl ester (pCTM-) chromophore and the surrounding amino acids act together to create a specifically stabilized pCTM- species. Particularly noteworthy is the role of the Arg52 amino acid in stabilizing the chromophore against autoionization, and the role of the Tyr42 and Glu46 amino acids in determining the hydrogen-bonding properties that carry the dominant energetic effects.
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Affiliation(s)
- Evgeniy V Gromov
- Theoretische Chemie, Physikalisch-Chemisches Institut Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
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Plaza P, Mahet M, Martin MM, Checcucci G, Lenci F. Target Analysis of Primary Photoprocesses Involved in the Oxyblepharismin-Binding Protein. J Phys Chem B 2007; 111:690-6. [PMID: 17249812 DOI: 10.1021/jp0642591] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Target analysis is performed on previously published transient absorption spectra of the 200-kDa oxyblepharismin-binding protein (OBIP) thought to trigger the photophobic response of the ciliate Blepharisma japonicum. The OBIP sample is considered as heterogeneous and made of two distinct classes of chromophore-protein complexes. A so-called nonreactive class is seen to be comparable to free oxyblepharismin in organic solution. Another, reactive, class is shown to undergo a fast picosecond photocycle involving the formation in 4 ps of an intermediate state noted Y1. The spectrum associated to Y1 bears striking similarities with that of the oxyblepharismin radical cation. This element favors the hypothesis that an excited-state intermolecular electron-transfer could be the primary step of the sensory transduction chain of B. japonicum. Proton release is also considered as a possible secondary step. These possibilities support the idea that reactive OBIP functions like an electron or proton pump. We alternatively propose a new hypothesis stating that the fast photocycle of reactive OBIP actually does not generate any photoproduct or protein change of conformation but is involved in another biological function. It would act as a kind of solar screen, providing additional protection to the light-adapted form of B. japonicum in case of excessive illumination.
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Affiliation(s)
- Pascal Plaza
- Département de Chimie, UMR 8640 CNRS-ENS, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France.
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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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Plaza P, Mahet M, Tchaikovskaya ON, Martin MM. Excitation energy effect on the early photophysics of hypericin in solution. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Miao W, Simpson AGB, Fu C, Lobban CS. The Giant Zooxanthellae-Bearing Ciliate Maristentor dinoferus (Heterotrichea) is Closely Related to Folliculinidae. J Eukaryot Microbiol 2005; 52:11-6. [PMID: 15702974 DOI: 10.1111/j.1550-7408.2005.3311r.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The small subunit rDNA sequence of Maristentor dinoferus (Lobban, Schefter, Simpson, Pochon, Pawlowski, and Foissner, 2002) was determined and compared with sequences from other Heterotrichea and Karyorelictea. Maristentor resembles Stentor in basic morphology and had been provisionally assigned to Stentoridae. However, our phylogenetic analyses show that Maristentor is more closely related to Folliculinidae. Our results support the creation of a separate family for Maristentor, Maristentoridae n. fam., and also confirm the phylogenetic grouping of Folliculindae, Stentoridae, Blepharismidae, and Maristentoridae, which we informally call 'stentorids'. Maristentor, rather than Stentor itself, appears to be most significant in understanding the origins of folliculinids from their aloricate ancestors. Our analyses suggest continued uncertainty in the exact placement of the root of heterotrichs with this phylogenetic marker.
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Affiliation(s)
- Wei Miao
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
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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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Changenet-Barret P, Espagne A, Plaza P, Hellingwerf KJ, Martin MM. Investigations of the primary events in a bacterial photoreceptor for photomotility: photoactive yellow protein (PYP). NEW J CHEM 2005. [DOI: 10.1039/b418134d] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Aramendía PF, Viappiani C, Wilkinson F. Editorial: Professor Silvia Braslavsky. Photochem Photobiol Sci 2003; 2:vii-viii. [PMID: 12911217 DOI: 10.1039/b305468c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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