850 research outputs found
Multi-Level Light Capture Control in Plants and Green Algae
No full textLife on Earth relies on photosynthesis, and the ongoing depletion of fossil carbon fuels has renewed interest in phototrophic light-energy conversion processes as a blueprint for the conversion of atmospheric CO2 into various organic compounds. Light-harvesting systems have evolved in plants and green algae, which are adapted to the light intensity and spectral composition encountered in their habitats. These organisms are constantly challenged by a fluctuating light supply and other environmental cues affecting photosynthetic performance. Excess light can be especially harmful, but plants and microalgae are equipped with different acclimation mechanisms to control the processing of sunlight absorbed at both photosystems. We summarize the current knowledge and discuss the potential for optimization of phototrophic light-energy conversion
Impaired Mitochondrial Transcription Termination Disrupts the Stromal Redox Poise in Chlamydomonas
No full textIn photosynthetic eukaryotes, the metabolite exchange between chloroplast and mitochondria ensures efficient photosynthesis under saturating light conditions. The Chlamydomonas reinhardtii mutant stm6 is devoid of the mitochondrial transcription termination factor MOC1 and aberrantly expresses the mitochondrial genome, resulting in enhanced photosynthetic hydrogen production and diminished light tolerance. We analyzed the modulation of mitochondrial and chlororespiration during the acclimation of stm6 and the MOC1-complemented strain to excess light. Although light stress stimulated mitochondrial respiration via the energy-conserving cytochrome c pathway in both strains, the mutant was unable to fine-tune the expression and activity of oxidative phosphorylation complex I in excess light, which was accompanied by an increased mitochondrial respiration via the alternative oxidase pathway. Furthermore, stm6 failed to fully activate chlororespiration and cyclic electron flow due to a more oxidized state of the chloroplast stroma, which is caused by an increased mitochondrial electron sink capacity. Increased susceptibility to photoinhibition of PSII in stm6 demonstrates that the MOC1-dependent modulation of mitochondrial respiration helps control the stromal redox poise as a crucial part of high-light acclimation in C. reinhardtii
The mTERF protein MOC1 terminates mitochondrial DNA transcription in the unicellular green alga Chlamydomonas reinhardtii
Full text linkWobbe L, Nixon PJ. The mTERF protein MOC1 terminates mitochondrial DNA transcription in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Research. 2013;41(13):6553-6567
Editorial: Microalgae Biology and Biotechnology
No full textPetroutsos D, Wobbe L, Jin ES, Ballottari M. Editorial: Microalgae Biology and Biotechnology. Frontiers in plant science. 2020;11: 628267
Impaired Mitochondrial Transcription Termination Disrupts the Stromal Redox Poise in Chlamydomonas.
No full textUhmeyer A, Cecchin M, Ballottari M, Wobbe L. Impaired Mitochondrial Transcription Termination Disrupts the Stromal Redox Poise in Chlamydomonas. Plant Physiol. 2017;174(3):1399-1419
Multi-Level Light Capture Control in Plants and Green Algae
No full textWobbe L, Bassi R, Kruse O. Multi-Level Light Capture Control in Plants and Green Algae. Trends in Plant Science. 2016;21(1):55-68
Integration of Carbon Assimilation Modes with Photosynthetic Light Capture in the Green Alga Chlamydomonas reinhardtii
No full textThe unicellular green alga Chlamydomonas reinhardtii is capable of using organic and inorganic carbon sources simultaneously, which requires the adjustment of photosynthetic activity to the prevailing mode of carbon assimilation. We obtained novel insights into the regulation of light-harvesting at photosystem II (PSII) following altered carbon source availability. In C. reinhardtii, synthesis of PSII-associated light-harvesting proteins (LHCBMs) is controlled by the cytosolic RNA-binding protein NAB1, which represses translation of particular LHCBM isoform transcripts. This mechanism is fine-tuned via regulation of the nuclear NAB1 promoter, which is activated when linear photosynthetic electron flow is restricted by CO(2)-limitation in a photoheterotrophic context. In the wild-type, accumulation of NAB1 reduces the functional PSII antenna size, thus preventing a harmful overexcited state of PSII, as observed in a NAB1-less mutant. We further demonstrate that translation control as a newly identified long-term response to prolonged CO(2)-limitation replaces LHCII state transitions as a fast response to PSII over-excitation. Intriguingly, activation of the long-term response is perturbed in state transition mutant stt7, suggesting a regulatory link between the long- and short-term response. We depict a regulatory circuit operating on distinct timescales and in different cellular compartments to fine-tune light-harvesting in photoheterotrophic eukaryotes
The unicellular green microalga Botryosphaerella sudetica links plant‐like light protection with an algal lifestyle
No full textSummary Nonphotochemical quenching (NPQ) mechanisms fine‐tune light utilisation in the photosynthetic antenna, for example, in response to excess light, to prevent photodamage. NPQ comprises distinct mechanisms, all contributing to photoprotection but acting on different time scales. Preferences for individual mechanisms and NPQ composition are proposed to reflect the organism's lifestyle, especially regarding sessile vs motile styles, with the latter enabling photophobic responses. We analysed photoprotection in the nonmotile, unicellular chlorophycean microalga Botryosphaerella sudetica , belonging to a genus known to form high‐light‐exposed floating aquatic biofilms. Growth, Chl fluorescence, its nuclear genome, and the expression of photoprotective genes were analysed in comparison with the motile chlorophycean microalga Chlamydomonas reinhardtii . These analyses revealed that B. sudetica is, in contrast to C. reinhardtii , equipped with a constitutive energy‐dependent quenching (qE) mechanism based on the constitutive accumulation of protein PSBS, the thylakoid lumen pH‐sensor, found throughout the green plant lineage. While qE was the predominant NPQ mechanism in B. sudetica and required zeaxanthin formation, state transitions (qT), which largely contributed to NPQ in C. reinhardtii , played a minor role. These data demonstrate that a core set of NPQ mechanisms conserved in the Viridiplantae is shuffled to meet better the adaptive requirements imposed by the habitat
Lutz Weltmann Correspondence Collection. 1923-1969 Bulk dates: 1930-1955
No full textThe Lutz Weltmann Correspondence Collection largely holds professional correspondence from others to Lutz Weltmann, a critic, publisher, author and teacher. Such correspondence often references various literary projects of Weltmann's or of the correspondents. One letter by him includes a brief curriculum vitae.Lutz Weltmann was born on February 15, 1901 in Elbing (now Elblag, Poland). He attended the universities of Berlin and Freiburg, receiving his doctorate in philosophy from the University of Freiburg in 1924. From 1924-1933 he was the theater and literature critic of Rudolf Mosse newspapers in Berlin, including the Berliner Volkszeitung, but also contributed as a freelance writer for the Frankfurter General-Anzeiger and the Kölnische Zeitung, among others. From 1927-1933 he was co-editor of the monthly Die Literatur (later titled Das literarische Echo). In 1934 he authored some articles for the Jüdisches Jahrbuch on Spinoza and in 1936 he lectured on Samuel Cooper for the Jüdischer Kulturbund and produced Jizchok Leib Perez's Die goldene Kette for the Kulturbund's theater. In the course of his work he came to know many other authors, critics and others in the field of literature and theater.After emigrating to England in 1939, he served in the British Pioneer Corps from 1940-1943. The following year he earned his teaching diploma in London in 1944 and then taught at various schools in Kent, London and Essex. He also wrote from England for West German newspapers after the war. During this time he was assistant editor of the series The Goethe Year 1749-1949- Das Goethe-Jahr 1749-1949, celebrating the bi-centenary of the birth of Goethe, and wrote a book on Kasimir Edschmid. He also wrote three unpublished works on Christopher Fry, T.S. Eliot, and on Shakespeare.All letters on the list "Briefe on Lutz Weltmann" not previously digitized were consolidated into this collectionProcesseddigitize
The molecular function of plant mTERFs as key regulators of organellar gene expression
No full textWobbe L. The molecular function of plant mTERFs as key regulators of organellar gene expression. Plant and Cell Physiology. 2020: pcaa132.The protein family of mTERFs (mitochondrial transcription termination factors) was initially studied in mammalian and insect mitochondria before the first Arabidopsis mTERF mutant was characterized. More than ten years of research on the function of plant mTERFs in the flowering plants A. thaliana, Z. mays and the green microalga C. reinhardtii has since highlighted that mTERFs are key regulators of organellar gene expression (OGE) in mitochondria as well as in chloroplasts. Additional functions to be fulfilled by plant mTERFs (e.g. splicing) and the fact that the expression of two organellar genomes had to be facilitated has led to a massive expansion of the plant mTERF portfolio compared to that found in mammals. Plant mTERFs are implicated in all steps of OGE ranging from the modulation of transcription to the maturation of tRNAs and hence translation. Furthermore, being regulators of OGE, mTERFs are required for a successful long-term acclimation to abiotic stress, retrograde signaling and interorganellar communication. Here, I review the recent progress in the elucidation of molecular mTERF functions
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