Photochemistry and Photobiology

Cover image for Vol. 92 Issue 3

Edited By: Jean Cadet

Impact Factor: 2.266

ISI Journal Citation Reports © Ranking: 2014: 44/73 (Biophysics); 184/290 (Biochemistry & Molecular Biology)

Online ISSN: 1751-1097

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  • Stress Tolerance of the Endemic Antarctic Brown Alga Desmarestia anceps to UV Radiation and Temperature is Mediated by High Concentrations of Phlorotannins

    Stress Tolerance of the Endemic Antarctic Brown Alga Desmarestia anceps to UV Radiation and Temperature is Mediated by High Concentrations of Phlorotannins

    In this study, we examine whether the different physiological abilities allowing D. anceps to grow across a wide depth range is determined by high levels of phlorotannins (UV-protective compounds). Photosynthesis, soluble phlorotannins content and antioxidant capacities were analyzed in response to different radiation (PAR and PAR+UV) and temperature (2, 7 and 12°C) conditions. High levels of soluble phlorotannins were detected and positively correlated with ROS scavenging capacity. In general, highest contents of phlorotannins were correlated with the lowest inhibition of Fv/Fm in all experimental treatments, highlighting the UV-protective role of these compounds in D. anceps.

  • High Temperature Affects Photosynthetic and Molecular Processes in Field-Cultivated Vitis vinifera L. × Vitis labrusca L.

    High Temperature Affects Photosynthetic and Molecular Processes in Field-Cultivated Vitis vinifera L. × Vitis labrusca L.

    Protective mechanisms of PS II, which included the changes in PS II activity and the expression levels of heat-response genes and HSP21, rapidly responded to heat stress at a critical high temperature (above 40°C) under field or controlled condition. Finally, the recovery of changes at 6 day suggested that grapes enhanced thermotolerance under heat stress by photosynthetic processes.

  • RESEARCH ARTICLE:The Involvement of Splicing Factor hnRNP A1 in UVB-induced Alternative Splicing of hdm2 (

    RESEARCH ARTICLE:The Involvement of Splicing Factor hnRNP A1 in UVB‐induced Alternative Splicing of hdm2 (

    Human homolog double minute 2 (hdm2), an oncoprotein, which binds to tumor suppressor p53 to facilitate its degradation, has been known to contribute to tumorigenesis. Its splicing variants are reported to be highly expressed in many cancers and can be induced by ultraviolet B light (UVB). However, the mechanisms of how UVB radiation induces hdm2 alternative splicing still remain unclear. In this study, we investigated the roles of two common splicing factors, heterogeneous nuclear ribonucleoproteins (hnRNP) A1 and serine/arginine-rich splicing factor 1 (SRSF1), in regulating UVB-induced hdm2 splicing. Our study indicated that while the expression of both hnRNP A1 and SRSF1 are induced, only hnRNP A1 is involved in hdm2 alternative splicing upon UVB irradiation. Overexpression of hnRNP A1 resulted in decrease of full-length hdm2 (hdm2-FL) and increase of hdm2B, one of hdm2 alternate-splicing forms; while down-regulated hnRNP A1 expression led to the decrease of the hdm2-FL and hdm2B in HaCaT cells. Protein-mRNA binding assay confirmed that UVB irradiation could increase the binding of hnRNP A1 to hdm2 pre-mRNA. In conclusion, we elucidated that UVB induces alternative splicing of hdm2 via increasing the expression and the binding of hnRNP A1 to hdm2 full-length mRNA.

  • RESEARCH ARTICLE:Stereoselective Self-Aggregation of 31-Epimerically Pure Amino Analogs of Zinc Bacteriochlorophyll-d in an Aqueous Micelle Solution

    RESEARCH ARTICLE:Stereoselective Self‐Aggregation of 31‐Epimerically Pure Amino Analogs of Zinc Bacteriochlorophyll‐d in an Aqueous Micelle Solution

    Zinc bacteriochlorophyll-d analogs possessing an amino group instead of the original hydroxy group at the C31 position were prepared by chemical modification of naturally occurring chlorophyll-a. The synthetic 31-epimers were successfully separated by reverse phase HPLC to give diastereomerically pure samples. The stereochemistry of the chiral C31-center in the separated amines was determined by NMR analysis of their diastereomeric amides as well as by their asymmetric synthesis from authentic stereoisomers. Both the epimers were monomeric in tetrahydrofuran to give sharp electronic absorption bands, while they self-aggregated to form chlorosomal oligomers with the redshifted bands in an aqueous Triton X-100 micelle solution (pH = 6.9). The resulting oligomers deaggregated by addition of p-toluenesulfonic acid to give monomeric N-protonated ammonium species. The aggregation and deaggregation were dependent on the 31-stereochemistry, indicating that each epimer produced supramolecularly different self-aggregates.

  • RESEARCH ARTICLE: Proteomonas sulcata ACR1: A Fast Anion Channelrhodopsin

    RESEARCH ARTICLE: Proteomonas sulcata ACR1: A Fast Anion Channelrhodopsin

    Natural channelrhodopsins with strictly anion selectivity and high unitary conductance have been recently discovered in the cryptophyte alga Guillardia theta. These proteins, called anion channelrhodopsins (ACRs), are of interest for their novel function and also because they were shown to be highly efficient tools to inhibit neuronal action potentials with light. We show that a homologous protein from the cryptophyte alga Proteomonas sulcata (named here PsuACR1) exhibits similar strict anion selectivity as the previously identified G. theta ACRs. Like G. theta ACRs, PsuACR1 lacks a protonatable residue at the position of the proton acceptor Asp-85 in bacteriorhodopsin, which may be a key characteristic of ACR family members shared by haloarchaeal chloride pumps. Of importance for its potential use in optogenetics, despite its 10-fold lower channel activity than the GtACRs, PsuACR1 exhibits an ~eightfold more rapid channel closing half-time making it uniquely suitable for silencing the subclass of high-frequency firing neurons when high-time resolution is needed. The existence of a rhodopsin with properties similar to G. theta ACRs in a different cryptophyte genus indicates that such proteins may be widespread in the phylum of cryptophyte algae.

  • Stress Tolerance of the Endemic Antarctic Brown Alga Desmarestia anceps to UV Radiation and Temperature is Mediated by High Concentrations of Phlorotannins
  • High Temperature Affects Photosynthetic and Molecular Processes in Field-Cultivated Vitis vinifera L. × Vitis labrusca L.
  • RESEARCH ARTICLE:The Involvement of Splicing Factor hnRNP A1 in UVB‐induced Alternative Splicing of hdm2 (
  • RESEARCH ARTICLE:Stereoselective Self‐Aggregation of 31‐Epimerically Pure Amino Analogs of Zinc Bacteriochlorophyll‐d in an Aqueous Micelle Solution
  • RESEARCH ARTICLE: Proteomonas sulcata ACR1: A Fast Anion Channelrhodopsin

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Synthetic DNA hairpins possessing a Michler’s ketone linker at one end separated from a perylenediimide base surrogate by four base pairs were designed to investigate transport of charge between the two chromophores. Pulsed laser excitation of Michler’s ketone with 400 nm light results in formation of a charge transfer excited state which returns to the group state without undergoing electron transport to perylenediimide (upper pathway). Excitation of perylenediimide with 545 nm light results in injection of a positive charge which is transported via the base pairs to Michler’s ketone (lower pathway). For details see the paper “Electronic Interactions of Michler’s Ketone with DNA Bases in Synthetic Hairpins” by Almaz S. Jalilov et al. on pages 739-747 in this issue.
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