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Shengyang Jin, Jian Sun, Tobias Wunder, Desong Tang, Asaph B Cousins, Siu Kwan Sze, Oliver Mueller-Cajar, Yong-Gui Gao
Aquatic microalgae have evolved diverse CO2-concentrating mechanisms (CCMs) to saturate the carboxylase with its substrate, to compensate for the slow kinetics and competing oxygenation reaction of the key photosynthetic CO2-fixing enzyme rubisco. The limiting CO2-inducible B protein (LCIB) is known to be essential for CCM function in Chlamydomonas reinhardtii To assign a function to this previously uncharacterized protein family, we purified and characterized a phylogenetically diverse set of LCIB homologs...
December 1, 2016: Proceedings of the National Academy of Sciences of the United States of America
Xiang Gao, Fengge Zhang, Jinlu Hu, Wenkai Cai, Ge Shan, Dongsheng Dai, Kaiyao Huang, Gaohong Wang
MicroRNAs play an important role in abiotic stress responses in higher plants and animals, but their role in stress adaptation in algae remains unknown. In this study, the expression of identified and putative miRNAs in Chlamydomonas reinhardtii was assessed using quantitative polymerase chain reaction; some of the miRNAs (Cre-miR906-3p) were up-regulated, whereas others (Cre-miR910) were down-regulated when the species was subjected to multiple abiotic stresses. With degradome sequencing data, we also identified ATP4 (the d-subunit of ATP synthase) and NCR2 (NADPH: cytochrome P450 reductase) as one of the several targets of Cre-miR906-3p and Cre-miR910, respectively...
December 2, 2016: Scientific Reports
Zareen Amtul, Amal A Aziz
Epilepsy is characterized by the hyperexcitability of various neuronal circuits that results due to the imbalance between glutamate-mediated excitation of voltage-gated cation channels and γ-amino butyric acid (GABA)-mediated inhibition of anion channels leading to aberrant, sporadic oscillations or fluctuations in neuronal electrical activity. Epilepsy with a risk of mortality and around 65 million sufferers of all ages all over the world is limited therapeutically with high rates of adverse reactions, lack of complete seizure control, and over 30% patients with refractory epilepsy...
December 1, 2016: Molecular Neurobiology
Inkar Castellanos-Huerta, Bernardo Bañuelos-Hernández, Guillermo Téllez, Sergio Rosales-Mendoza, Luis G Brieba, Elizabeth Esquivel-Ramos, Josué I Beltrán-López, Gilberto Velazquez, Isidro Fernandez-Siurob
Globally, avian influenza (AI) is a serious problem in poultry farming. Despite vaccination, the prevalence of AI in México highlights the need for new approaches to control AI and to reduce the economic losses associated with its occurrence in susceptible birds. Recombinant proteins from avian influenza virus (AIV) have been expressed in different organisms, such as plants. The present study investigated the feasibility of designing and expressing the HA protein of AIV in the transplastomic microalga Chlamydomonas reinhardtii as a novel approach for AIV control and taking advantage of culture conditions, its reproductive range, and safe use in consideration of the generally regarded as safe food ingredient regulatory classification...
December 2016: Avian Diseases
Wojciech Pokora, Anna Aksmann, Agnieszka Baścik-Remisiewicz, Agnieszka Dettlaff-Pokora, Max Rykaczewski, Magdalena Gappa, Zbigniew Tukaj
The present study aimed to evaluate the possible relationship between the changes in hydrogen peroxide (H2O2) and nitric oxide (NO) content and the course of growth and reproductive processes of the cell cycle of Chlamydomonas reinhardtii. The peak of H2O2 observed at the beginning of the cell cycle was found to originate from Fe-SOD and Mn-SODchl. activity and result from the alternation in the photosynthetic processes caused by the dark-to-light transition of daughter cells. A rapid increase in NO concentration, observed before the light-to-dark cell transition, originated from NR and NIR activity and was followed by a photosynthesis-independent, Mn-SODchl...
November 15, 2016: Journal of Plant Physiology
Imad Aharchaou, Maikel Rosabal, Fengjie Liu, Eric Battaglia, Davide A L Vignati, Claude Fortin
Chromium occurs in aquatic environments under two main redox forms, namely Cr(III) and Cr(VI), with different geochemical and biochemical properties. Cr(VI) readily crosses biological membranes of living organisms and once inside the cells it undergoes a rapid reduction to Cr(III). The route of entry for the latter form is, however, poorly known. Using the radioactive tracer (51)Cr we compared the accumulation (absorption and adsorption) of the two Cr forms by the green unicellular alga Chlamydomonas reinhardii after 1h and 72h of exposure to 100nM of either Cr(III) or Cr(VI) at pH 7...
November 6, 2016: Aquatic Toxicology
Marilyn P Sequeira, Sapna Sinha, Mustafa J Motiwalla, Venkatramanan G Rao, Jacinta S D'Souza
The long-flagella mutants (lf1, lf2, lf3 and lf4) of Chlamydomonas reinhardtii are defective in proteins that are required for the assembly of normal flagella, their phenotype being long flagella. In a previous study, we biophysically characterized these mutants for their waveform patterns, swimming speeds, beat frequencies and correlated these parameters with their flagellar lengths. We found an anomaly in this correlation and set out to explore the underlying molecular significance, if any. The diverse inner dynein isoforms are the flagellar motors that convert the chemical energy of ATP into the mechanical energy of motility; we probed the presence of one of these isoforms (DHC11, which might help in bend initiation) in the lf mutants and compared it with the wild-type...
November 16, 2016: Biochemical and Biophysical Research Communications
Dominik Ziehe, Beatrix Dünschede, Mira Zenker, Silke Funke, Marc M Nowaczyk, Danja Schünemann
The bacterial signal recognition particle (SRP) mediates the cotranslational targeting of membrane proteins and is a high affinity complex consisting of a SRP54 protein subunit (Ffh) and an SRP RNA. The chloroplast SRP (cpSRP) pathway has adapted throughout evolution to enable the posttranslational targeting of the light harvesting chlorophyll a/b binding proteins (LHCPs) to the thylakoid membrane. In spermatophytes (seed plants), the cpSRP lacks the SRP RNA and is instead formed by a high affinity interaction of the conserved 54-kD subunit (cpSRP54) with the chloroplast-specific cpSRP43 protein...
2016: PloS One
Kenneth Wei Min Tan, Huixin Lin, Hui Shen, Yuan Kun Lee
Certain species of microalgae are natural accumulators of lipids, while others are more inclined to store starch. However, what governs the preference to store lipids or starch is not well understood. In this study, the microalga Dunaliella tertiolecta was used as a model to study the global gene expression profile regulating starch accumulation in microalgae. D. tertiolecta, when depleted of nitrogen, produced only 1% of dry cell weight (DCW) in neutral lipids, while starch was rapidly accumulated up to 46% DCW...
November 16, 2016: Scientific Reports
Adriana Garibay-Hernández, Bronwyn J Barkla, Rosario Vera-Estrella, Alfredo Martinez, Omar Pantoja
Ettlia oleoabundans is a non-sequenced oleaginous green microalga. Despite the significant biotechnological interest in producing value-added compounds from the acyl-lipids of this microalga, a basic understanding of the physiology and biochemistry of oleaginous microalgae is lacking, especially under nitrogen deprivation conditions known to trigger lipid accumulation. Using an RNA-Seq-based proteomics approach together with manual annotation, we are able to provide the first membrane proteome of an oleaginous microalga...
November 8, 2016: Plant Physiology
Deborah E Shelton, Martin P Leslie, Richard E Michod
We develop and compare two models for division initiation in cells of the unicellular green alga Chlamydomonas reinhardtii, a topic that has remained controversial in spite of years of empirical work. Achieving a better understanding of C. reinhardtii cell cycle regulation is important because this species is used in studies of fundamental eukaryotic cell features and in studies of the evolution of multicellularity. C. reinhardtii proliferates asexually by multiple fission, interspersing rapid rounds of symmetric division with prolonged periods of growth...
November 2, 2016: Journal of Theoretical Biology
Celma Estefanía Ochoa-Méndez, Ignacio Lara-Hernández, Luzmila Martínez González, Patricia Aguirre-Bañuelos, Maximiliano Ibarra-Barajas, Patricia Castro-Moreno, Omar González-Ortega, Ruth Elena Soria-Guerra
In this study, we developed a transplastomic C. reinhardtii strain that accumulates anti-hypertensive peptides. Tandem repeats of VLPVP peptide were included. PCR analysis confirmed the presence of the transgene in the modified strains. After in vitro digestion of biomass of a recombinant C. reinhardtii strain the VLVPV peptide was identified and quantified by HPLC. The highest expression line produced 0.292mg of recombinant protein per mg of freeze-dried biomass. Intragastric administration of the genetically modified strain to spontaneous hypertensive rats at a dose of 30mg/kg of body weight of recombinant protein significantly reduced systolic blood pressure...
November 2, 2016: Journal of Biotechnology
Yooeun Chae, Dokyung Kim, Youn-Joo An
Although fluoride occurs naturally in the environment, excessive amounts of fluoride in freshwater and terrestrial ecosystems can be harmful. We evaluated the toxicity of fluoride compounds on the growth, viability, and photosynthetic capacity of freshwater (Chlamydomonas reinhardtii and Pseudokirchneriella subcapitata) and terrestrial (Chlorococcum infusionum) algae. To measure algal growth inhibition, a flow cytometric method was adopted (i.e., cell size, granularity, and auto-fluorescence measurements), and algal yield was calculated to assess cell viability...
October 28, 2016: Environmental Pollution
Joseph Longworth, Danying Wu, María Huete-Ortega, Phillip C Wright, Seetharaman Vaidyanathan
Nitrogen stress is a common strategy employed to stimulate lipid accumulation in microalgae, a biofuel feedstock of topical interest. Although widely investigated, the underlying mechanism of this strategy is still poorly understood. We examined the proteome response of lipid accumulation in the model diatom, Phaeodactylum tricornutum (CCAP 1055/1), at an earlier stage of exposure to selective nitrogen exclusion than previously investigated, and at a time point when changes would reflect lipid accumulation more than carbohydrate accumulation...
September 2016: Algal research
Kaori Matsuda, Yousuke Shimoda, Ayumi Tanaka, Hisashi Ito
Mg removal from chlorophyll by Mg-dechelatase is the first step of chlorophyll degradation. Recent studies showed that in Arabidopsis, Stay Green (SGR) encodes Mg-dechelatase. Though the Escherichia coli expression system is advantageous for investigating the properties of Mg-dechelatase, Arabidopsis Mg-dechelatase is not successfully expressed in E. coli. Chlamydomonas reinhardtii SGR (CrSGR) has a long, hydrophilic tail, suggesting that active CrSGR can be expressed in E. coli. After the incubation of chlorophyll a with CrSGR expressed in E...
October 24, 2016: Plant Physiology and Biochemistry: PPB
Qiao-Guo Tan, Guang Yang, Kevin J Wilkinson
The applicability of the biotic ligand model (BLM) was tested with respect to the biouptake of the lanthanide Sm by the freshwater green alga, Chlamydomonas reinhardtii. In the absence of organic ligands, Sm uptake was well described by the Michaelis-Menten equation, consistent with the BLM assumption of single transporter, with the maximum influx rate (Jmax) of 1.5 × 10(-14) mol cm(-2) s(-1) and a binding constant (KSm) of 10(7.0) M(-1). The addition of organic ligands (i.e., malic acid, diglycolic acid and citric acid) decreased Sm influx rates, however, the decreases were much less than that predicted by the BLM, possibly due to the direct contribution of the Sm complexes...
October 28, 2016: Chemosphere
Anne Dueck, Maurits Evers, Stefan R Henz, Katharina Unger, Norbert Eichner, Rainer Merkl, Eugene Berezikov, Julia C Engelmann, Detlef Weigel, Stephan Wenzl, Gunter Meister
BACKGROUND: Volvox carteri (V. carteri) is a multicellular green alga used as model system for the evolution of multicellularity. So far, the contribution of small RNA pathways to these phenomena is not understood. Thus, we have sequenced V. carteri Argonaute 3 (VcAGO3)-associated small RNAs from different developmental stages. RESULTS: Using this functional approach, we define the Volvox microRNA (miRNA) repertoire and show that miRNAs are not conserved in the closely related unicellular alga Chlamydomonas reinhardtii...
November 2, 2016: BMC Genomics
Lianyong Wang, Takashi Yamano, Shunsuke Takane, Yuki Niikawa, Chihana Toyokawa, Shin-Ichiro Ozawa, Ryutaro Tokutsu, Yuichiro Takahashi, Jun Minagawa, Yu Kanesaki, Hirofumi Yoshikawa, Hideya Fukuzawa
Aquatic photosynthetic organisms, including the green alga Chlamydomonas reinhardtii, induce a CO2-concentrating mechanism (CCM) to maintain photosynthetic activity in CO2-limiting conditions by sensing environmental CO2 and light availability. Previously, a novel high-CO2-requiring mutant, H82, defective in the induction of the CCM, was isolated. A homolog of calcium (Ca(2+))-binding protein CAS, originally found in Arabidopsis thaliana, was disrupted in H82 cells. Although Arabidopsis CAS is reported to be associated with stomatal closure or immune responses via a chloroplast-mediated retrograde signal, the relationship between a Ca(2+) signal and the CCM associated with the function of CAS in an aquatic environment is still unclear...
November 1, 2016: Proceedings of the National Academy of Sciences of the United States of America
Joris J Snellenburg, Lucyna M Wlodarczyk, Jan P Dekker, Rienk van Grondelle, Ivo H M van Stokkum
The regulatory mechanism of state transitions was studied in Chlamydomonas reinhardtii (C.r.) wild type (WT) as well as mutant strains deficient in the photosystem I (PSI) or the photosystem II (PSII) core. Time-resolved fluorescence measurements were obtained on instantly frozen cells incubated beforehand in the dark in aerobic or anaerobic conditions which leads to state 1 (S1) or state 2 (S2). WT data contains information on the light-harvesting complex (LHC) connected to PSI and PSII. The mutants' data contain information on either LHCII-LHCI-PSI or LHCII-PSII, plus information on LHC antennas devoid of a PS core...
January 2017: Biochimica et Biophysica Acta
Clare F Megarity, Julian Esselborn, Suzannah V Hexter, Florian Wittkamp, Ulf-Peter Apfel, Thomas Happe, Fraser A Armstrong
Protein film electrochemistry (PFE) has been used to study the assembly of the complex 6Fe active site of [FeFe]-hydrogenases (known as the H-cluster) from its precursors the [4Fe 4S] domain that is already coordinated within the host and the 2Fe domain that is presented as a synthetic water-soluble complex stabilized by an additional CO. Not only does PFE allow control of redox states via the electrode potential, but the immobilized state of the enzyme facilitates control of extremely low concentrations of the 2Fe complex...
October 24, 2016: Journal of the American Chemical Society
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