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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
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
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
Dawei Han, Bruce A Young
The Calabar burrowing python (Calabaria reinhardtii) has a unique combination of marked thickness of the integumentary layers, a highly organized lamellate arrangement of the dermal collagen bundles, and a reduction in the size of the interscale hinge region of the integument. Biomechanical testing demonstrates that the skin of C. reinhardtii is more resistant to penetration than the skin of other snakes. The laminar arrangement of the collagen bundles provides for penetrative resistance, even while maintaining the flexibility characteristic of snake skin...
October 21, 2017: Journal of Morphology
Vladimir Pelmenschikov, James A Birrell, Cindy C Pham, Nakul Mishra, Hongxin Wang, Constanze Sommer, Edward Reijerse, Casseday P Richers, Kenji Tamasaku, Yoshitaka Yoda, Thomas B Rauchfuss, Wolfgang Lubitz, Stephen P Cramer
[FeFe]-hydrogenases are metalloenzymes that reversibly reduce protons to molecular hydrogen at exceptionally high rates. We have characterized the catalytically competent hydride state (Hhyd) in the [FeFe]-hydrogenases from both Chlamydomonas reinhardtii and Desulfovibrio desulfuricans using (57)Fe nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT). H/D exchange identified two Fe-H bending modes originating from the binuclear iron cofactor. DFT calculations show that these spectral features result from an iron-bound terminal hydride, and the Fe-H vibrational frequencies being highly dependent on interactions between the amine base of the catalytic cofactor with both hydride and the conserved cysteine terminating the proton transfer chain to the active site...
November 9, 2017: Journal of the American Chemical Society
Inmaculada Couso, María Esther Pérez-Pérez, Enrique Martínez-Force, Hee-Sik Kim, Yonghua He, James G Umen, José L Crespo, Peter Bozhkov
Autophagy is an intracellular catabolic process that allows cells to recycle unneeded or damaged material to maintain cellular homeostasis. This highly dynamic process is characterized by the formation of double-membrane vesicles called autophagosomes, which engulf and deliver the cargo to the vacuole. Flow of material through the autophagy pathway and its degradation in the vacuole is known as autophagic flux, and reflects the autophagic degradation activity. A number of assays have been developed to determine autophagic flux in yeasts, mammals, and plants, but it has not been examined yet in algae...
October 19, 2017: Journal of Experimental Botany
Ekaterina Minaeva, Zhanneta Zalutskaya, Valentina Filina, Elena Ermilova
Truncated hemoglobins constitute a large family, present in bacteria, in archaea and in eukaryotes. However, a majority of physiological functions of these proteins remains to be elucidated. Identification and characterization of a novel role of truncated hemoglobins in the model alga provides a framework for a more complete understanding of their biological functions. Here, we use quantitative RT-PCR to show that three truncated hemoglobins of Chlamydomonas reinhardtii, THB1, THB2 and THB12, are induced under conditions of depleted sulfur (S) supply...
2017: PloS One
Alejandra Jiménez-Suárez, Miriam Vázquez-Acevedo, Héctor Miranda-Astudillo, Diego González-Halphen
Subunit II of cytochrome c oxidase (Cox2) is usually encoded in the mitochondrial genome, synthesized in the organelle, inserted co-translationally into the inner mitochondrial membrane, and assembled into the respiratory complex. In chlorophycean algae however, the cox2 gene was split into the cox2a and cox2b genes, and in some algal species like Chlamydomonas reinhardtii and Polytomella sp. both fragmented genes migrated to the nucleus. The corresponding Cox2A and Cox2B subunits are imported into mitochondria forming a heterodimeric Cox2 subunit...
October 17, 2017: Journal of Bioenergetics and Biomembranes
Justin Findinier, Hande Tunçay, Miriam Schulz-Raffelt, Philippe Deschamps, Corentin Spriet, Jean-Marie Lacroix, Thierry Duchêne, Nicolas Szydlowski, Yonghua Li-Beisson, Gilles Peltier, Christophe D'Hulst, Fabrice Wattebled, David Dauvillée
The MEX1 locus of Chlamydomonas reinhardtii was identified in a genetic screen as a factor that affects starch metabolism. Mutation of MEX1 causes a slow-down in the mobilization of storage polysaccharide. Cosegregation and functional complementation analyses were used to assess the involvement of the Mex1 protein in starch degradation. Heterologous expression experiments performed in Escherichia coli and Arabidopsis thaliana allowed us to test the capacity of the algal protein in maltose export. In contrast to the A...
October 5, 2017: Journal of Experimental Botany
Jing Xia, Lun Li, Tiantian Li, Zhiwei Fang, Kevin Zhang, Junfei Zhou, Hai Peng, Weixiong Zhang
MicroRNAs form an essential class of post-transcriptional gene regulator of eukaryotic species, and play critical parts in development and disease and stress responses. MicroRNAs may originate from various genomic loci, have structural characteristics, and appear in canonical or modified forms, making them subtle to detect and analyze. We present miRvial, a robust computational method and companion software package that supports parameter adjustment and visual inspection of candidate microRNAs. Extensive results comparing miRvial and six existing microRNA finding methods on six model organisms, Mus musculus, Drosophila melanogaste, Arabidopsis thaliana, Oryza sativa, Physcomitrella patens and Chlamydomonas reinhardtii, demonstrated the utility and rigor of miRvial in detecting novel microRNAs and characterizing features of microRNAs...
September 19, 2017: Nucleic Acids Research
Katherine E Helliwell, Jagroop Pandhal, Matthew B Cooper, Joseph Longworth, Ulrich Johan Kudahl, David A Russo, Eleanor V Tomsett, Freddy Bunbury, Deborah L Salmon, Nicholas Smirnoff, Phillip C Wright, Alison G Smith
The unicellular green alga Lobomonas rostrata requires an external supply of vitamin B12 (cobalamin) for growth, which it can obtain in stable laboratory cultures from the soil bacterium Mesorhizobium loti in exchange for photosynthate. We investigated changes in protein expression in the alga that allow it to engage in this mutualism. We used quantitative isobaric tagging (iTRAQ) proteomics to determine the L. rostrata proteome grown axenically with B12 supplementation or in coculture with M. loti. Data are available via ProteomeXchange (PXD005046)...
October 16, 2017: New Phytologist
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