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Melis Düner, Jan Lambertz, Carolin Mügge, Anja Hemschemeier
Oxygenic phototrophs frequently encounter environmental conditions that result in intracellular energy crises. Growth of the unicellular green alga Chlamydomonas reinhardtii in hypoxia in the light depends on acclimatory responses of which the induction of photosynthetic cyclic electron flow is essential. The microalga cannot grow in the absence of molecular oxygen (O2 ) in the dark, although it possesses an elaborate fermentation metabolism. Not much is known about how the microalga senses and signals the lack of O2 or about its survival strategies during energy crises...
November 21, 2017: Plant Journal: for Cell and Molecular Biology
Haoxuan Liu, Ju Huang, Xiaoguang Sun, Jing Li, Yingwen Hu, Luyao Yu, Gianni Liti, Dacheng Tian, Laurence D Hurst, Sihai Yang
GC-favouring gene conversion enables fixation of deleterious alleles, disturbs tests of natural selection and potentially explains both the evolution of recombination as well as the commonly reported intragenomic correlation between G+C content and recombination rate. In addition, gene conversion disturbs linkage disequilibrium, potentially affecting the ability to detect causative variants. However, the importance and generality of these effects is unresolved, not simply because direct analyses are technically challenging but also because previous within- and between-species discrepant results can be hard to appraise owing to methodological differences...
November 20, 2017: Nature ecology & evolution
Yuting Wang, Xinqin Jiang, Changxing Hu, Ting Sun, Zhiyong Zeng, Xiaoqi Cai, Hui Li, Zhangli Hu
Background: Chlamydomonas reinhardtii is an ideal model organism not only for the study of basic metabolic processes in both plants and animals but also the production of biofuels including hydrogen. Transgenic analysis of C. reinhardtii is now well established and very convenient, but inducible exogenous gene expression systems remain under-studied. The most commonly used heat shock-inducible system has serious effects on algal cell growth and is difficult and costly to control in large-scale culture...
2017: Biotechnology for Biofuels
Kwangryul Baek, Jihyeon Yu, Jooyeon Jeong, Sang Jun Sim, Sangsu Bae, EonSeon Jin
Lutein and zeaxanthin are dietary carotenoids reported to be protective against age-related macular degeneration. Recently, the green alga Chlamydomonas reinhardtii has received attention as a photosynthetic cell factory, but the potential of this alga for carotenoid production has not yet been evaluated. In this study, we selected the C. reinhardtii CC-4349 strain as the best candidate among seven laboratory strains tested for carotenoid production. A knock-out mutant of the zeaxanthin epoxidase gene induced by preassembled DNA-free CRISPR-Cas9 ribonucleoproteins in the CC-4349 strain had a significantly higher zeaxanthin content (56-fold) and productivity (47-fold) than the wild type without the reduction in lutein level...
November 18, 2017: Biotechnology and Bioengineering
Yury S Bykov, Miroslava Schaffer, Svetlana O Dodonova, Sahradha Albert, Jürgen M Plitzko, Wolfgang Baumeister, Benjamin D Engel, John Ag Briggs
COPI-coated vesicles mediate trafficking within the Golgi apparatus and from the Golgi to the endoplasmic reticulum. The structures of membrane protein coats, including COPI, have been extensively studied with in vitro reconstitution systems using purified components. In a previous paper (Dodonova et al., 2017), we determined a complete structural model of the in vitro reconstituted COPI coat. Here, we applied cryo-focused ion beam milling, cryo-electron tomography and subtomogram averaging to determine the native structure of the COPI coat within vitrified Chlamydomonas reinhardtii cells...
November 17, 2017: ELife
Changfeng Qu, Yingying He, Zhou Zheng, Meiling An, Lulu Li, Xixi Wang, Xiaodong He, Yibin Wang, Fangming Liu, Jinlai Miao
The α-carbonic anhydrase (α-CA) is a zinc ion-containing enzyme that catalyzes the hydration of carbon dioxide. In this paper, a full-length α-CA gene was cloned from Chlamydomonas sp. ICE-L using RT-PCR and RACE-PCR for bioinformatic analysis. The α-CA open reading frame obtained by PCR was cloned into a vector and transformed into Escherichia coli to generate α-CA-producing bacteria. The α-CA was highly expressed upon induction with isopropyl-β-d-thiogalactoside (IPTG) at a final concentration of 0...
November 14, 2017: Molecular Biotechnology
Javier Ávila-Román, Elena Talero, Carolina de Los Reyes, Sofía García-Mauriño, Virginia Motilva
Oxylipins (OXLs) are bioactive molecules generated by the oxidation of fatty acids that promote the resolution of acute inflammation and prevent chronic inflammatory processes through molecular mechanisms that are not well known. We have previously reported the anti-inflammatory activity of microalgae-derived OXLs and OXL-containing biomass in two inflammatory bowel disease (IBD) models: 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced acute colitis and TNBS-induced recurrent colitis. In this study, we examined the in vitro anti-inflammatory mechanism of action of the most abundant OXLs isolated from Chlamydomonas debaryana (13S-HOTE and 13S-HODE) and Nannochloropsis gaditana (15S-HEPE)...
November 9, 2017: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
Gabriel Yvon-Durocher, Charlotte-Elisa Schaum, Mark Trimmer
The elemental composition of phytoplankton (C:N:P stoichiometry) is a critical factor regulating nutrient cycling, primary production and energy transfer through planktonic food webs. Our understanding of the multiple direct and indirect mechanisms through which temperature controls phytoplankton stoichiometry is however incomplete, increasing uncertainty in the impacts of global warming on the biogeochemical functioning of aquatic ecosystems. Here, we use a decade-long warming experiment in outdoor freshwater ponds to investigate how temperature-driven turnover in species composition and shifts in stoichiometric traits within species through local thermal adaptation contribute to the effects of warming on seston stoichiometry...
2017: Frontiers in Microbiology
Sonia Singhal
New biological variation originates from mutations, so understanding their effects-and how those effects vary with environment or genetic background-is critical to evolutionary studies. Kraemer et al. (2017) sequenced and measured the fitness of Chlamydomonas reinhardtii lineages that had experienced minimal selection. They found that mutations in these lineages had a small average deleterious effect attributable to mutations in coding regions, and average mutational effects varied depending on the ancestor's genotype...
November 6, 2017: Evolution; International Journal of Organic Evolution
Chang-Gui Pan, Feng-Jiao Peng, Wen-Jun Shi, Li-Xin Hu, Xiao-Dong Wei, Guang-Guo Ying
Triclosan (TCS) is an antibacterial and antifungal agent widely used in personal care products (PCPs). We investigated the effects of TCS (20μg/L, 100μg/L and 500μg/L) on Chlamydomonas reinhardtii by measuring the algal growth, chlorophyll content, lipid peroxidation, and transcription of the antioxidant-related genes (superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), glutathione S-transferase (GST), plastid terminal oxidase 2 (PTOX) and thioredoxin (TRX)) as well as biochemical alterations...
October 31, 2017: Ecotoxicology and Environmental Safety
Zhanneta Zalutskaya, Mariya Ostroukhova, Valentina Filina, Elena Ermilova
The mitochondrial respiratory chain in plants, many fungi and some protists consists of the ATP-coupling cyanide-sensitive cytochrome pathway and the cyanide-resistant alternative respiratory pathway. The alternative pathway is mediated by alternative oxidase (AOX). In unicellular algae, AOXs are monomeric fungi-type proteins. Studies performed in the model plant Chlamydomonas reinhardtii showed that a range of stress factors lead to induction of its AOX1. However, signaling molecules that trigger upregulation of AOX1 have not yet been identified...
October 28, 2017: Journal of Plant Physiology
Mark Rütgers, Ligia Segatto Muranaka, Timo Mühlhaus, Frederik Sommer, Sylvia Thoms, Juliane Schurig, Felix Willmund, Miriam Schulz-Raffelt, Michael Schroda
We have identified 39 proteins that interact directly or indirectly with high confidence with chloroplast HSP22E/F under heat stress thus revealing chloroplast processes affected by heat. Under conditions promoting protein unfolding, small heat shock proteins (sHsps) prevent the irreversible aggregation of unfolding proteins by integrating into forming aggregates. Aggregates containing sHsps facilitate the access of Hsp70 and ClpB/Hsp104 chaperones, which in ATP-dependent reactions disentangle individual proteins from the aggregates and assist in their refolding to the native state...
November 1, 2017: Plant Molecular Biology
Louis Dumas, Francesca Zito, Stéphanie Blangy, Pascaline Auroy, Xenie Johnson, Gilles Peltier, Jean Alric
The cytochrome (cyt) b6f complex and Stt7 kinase regulate the antenna sizes of photosystems I and II through state transitions, which are mediated by a reversible phosphorylation of light harvesting complexes II, depending on the redox state of the plastoquinone pool. When the pool is reduced, the cyt b6f activates the Stt7 kinase through a mechanism that is still poorly understood. After random mutagenesis of the chloroplast petD gene, coding for subunit IV of the cyt b6f complex, and complementation of a ΔpetD host strain by chloroplast transformation, we screened for impaired state transitions in vivo by chlorophyll fluorescence imaging...
November 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Yongguang Jiang, Peng Xiao, Qing Shao, Huan Qin, Zhangli Hu, Anping Lei, Jiangxin Wang
BACKGROUND: Microalgae have been demonstrated to be among the most promising phototrophic species for producing renewable biofuels and chemicals. Ethanol and butanol are clean energy sources with good chemical and physical properties as alternatives to gasoline. However, biosynthesis of these two biofuels has not been achieved due to low tolerance of algal cells to ethanol or butanol. RESULTS: With an eye to circumventing these problems in the future and engineering the robust alcohol-producing microalgal hosts, we investigated the metabolic responses of the model green alga Chlamydomonas reinhardtii to ethanol and butanol...
2017: Biotechnology for Biofuels
Kyoko Yarimizu, Ricardo Cruz-López, Hendrik Auerbach, Larissa Heimann, Volker Schünemann, Carl J Carrano
The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood with two basic strategies being distinguished: Strategy I involves the induction of an Fe(III)-chelate reductase (ferrireductase) along with Fe(II) or Fe(III) transporter proteins while strategy II plants have evolved sophisticated systems based on high-affinity, iron specific, binding compounds called phytosiderophores. In contrast, there is little knowledge about the corresponding systems in marine, plant-like lineages...
October 24, 2017: Biometals: An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine
Syed Lal Badshah, Junlei Sun, Sam Mula, Mike Gorka, Patricia Baker, Rajiv Luthra, Su Lin, Art van der Est, John H Golbeck, Kevin E Redding
In Photosystem I, light-induced electron transfer can occur in either of two symmetry-related branches of cofactors, each of which is composed of a pair of chlorophylls (ec2A/ec3A or ec2B/ec3B) and a phylloquinone (PhQA or PhQB). The axial ligand to the central Mg(2+) of the ec2A and ec2B chlorophylls is a water molecule that is also H-bonded to a nearby Asn residue. Here, we investigate the importance of this interaction for charge separation by converting each of the Asn residues to a Leu in the green alga, Chlamydomonas reinhardtii, and the cyanobacterium, Synechocystis sp...
October 21, 2017: Biochimica et Biophysica Acta
Bin Dong, Rong-Qiang Cheng, Qing-Yan Liu, Jing Wang, Zhen-Chuan Fan
In this study, an antimicrobial peptide composed of three tandem repeats of Mytichitin-A (3 × Mytichitin-A) with a designed molecular weight of approximately 25 kDa was expressed in the green alga Chlamydomonas reinhardtii. The yield of 3 × Mytichitin-A reached 0.28% of the total soluble protein of the 3 × Mytichitin-A-expressing transgenic cells and the expression level was stable following continuous passaging of the cells for six months. Compared to its natural and yeast-produced recombinant counterparts, which showed a very low level of growth inhibition of gram-negative bacteria, the 3 × Mytichitin-A inhibited the growth of gram-negative bacteria at a minimum inhibition concentration value ranging between 60 and 80 μg/ml...
October 20, 2017: Journal of Bioscience and Bioengineering
María Esther Pérez-Pérez, Inmaculada Couso, Luis G Heredia-Martínez, José L Crespo
Autophagy is an intracellular catabolic system that delivers cytoplasmic constituents and organelles in the vacuole. This degradative process is mediated by a group of proteins coded by autophagy-related (ATG) genes that are widely conserved from yeasts to plants and mammals. Homologs of ATG genes have been also identified in algal genomes including the unicellular model green alga Chlamydomonas reinhardtii. The development of specific tools to monitor autophagy in Chlamydomonas has expanded our current knowledge about the regulation and function of this process in algae...
October 22, 2017: Cells
Takashi Moriyama, Masakazu Toyoshima, Masakazu Saito, Hajime Wada, Naoki Sato
The precise localization of the lipid droplets and the metabolic pathways associated with the oil production are crucial to the engineering of microalgae for biofuel production. Several studies have reported detecting lipid droplets within the chloroplast of the microalga Chlamydomonas reinhardtii (Chlamydomonas), which accumulates considerable amount of triacylglycerol (TAG) and starch within the cell under nitrogen deprivation or high-light stress conditions. Starch undoubtedly accumulates within the chloroplast, but there have been debates on the localization of the lipid droplets, which are cytosolic organelles in other organisms...
October 23, 2017: Plant Physiology
(no author information available yet)
[This corrects the article DOI: 10.1371/journal.pgen.1006996.].
October 2017: PLoS Genetics
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