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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
Jan Jehlička, Adam Culka, Linda Nedbalová
We tested the potential of a miniaturized Raman spectrometer for use in field detection of snow algae pigments. A miniature Raman spectrometer, equipped with an excitation laser at 532 nm, allowed for the detection of carotenoids in cells of Chloromonas nivalis and Chlamydomonas nivalis at different stages of their life cycle. Astaxanthin, the major photoprotective pigment, was detected in algal blooms originating in snows at two alpine European sites that differed in altitude (Krkonoše Mts., Czech Republic, 1502 m a...
November 30, 2016: Astrobiology
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
Huan Long, Fan Zhang, Nannan Xu, Gai Liu, Dennis R Diener, Joel L Rosenbaum, Kaiyao Huang
Primary and motile cilia/flagella function as cellular antennae, receiving signals from the environment and subsequently activating signaling pathways that are critical for cellular homeostasis and differentiation [1-3]. Recent work with the green alga Chlamydomonas and the nematode C. elegans demonstrated that ectosomes can be released from the cilium and can mediate the intercellular communication [4-9]. To better understand the function of flagellar ectosomes, we have compared their protein composition to that of the flagellar membrane from which they are derived...
November 10, 2016: Current Biology: CB
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
S T Gumbi, B M Majeke, A O Olaniran, T Mutanda
Exploring indigenous microalgae capable of producing significant amounts of neutral lipids through high-throughput screening is crucial for sustainable biodiesel production. In this study, 31 indigenous microalgal strains were isolated from diverse aquatic habitats in KwaZulu-Natal, South Africa. Eight superior lipid-producing strains were selected for further analysis, based on Nile red fluorescence microscopy screening. The microalgal isolates were identified to belong to the genera Chlorella, Neochloris and Chlamydomonas via morpho-taxonomic and molecular approach by 18S rRNA gene sequencing...
November 18, 2016: Applied Biochemistry and Biotechnology
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
Iman Tabatabaei, Stephanie Ruf, Ralph Bock
A new selectable marker gene for stable transformation of the plastid genome was developed that is similarly efficient as the aadA, and produces no background of spontaneous resistance mutants. More than 25 years after its development for Chlamydomonas and tobacco, the transformation of the chloroplast genome still represents a challenging technology that is available only in a handful of species. The vast majority of chloroplast transformation experiments conducted thus far have relied on a single selectable marker gene, the spectinomycin resistance gene aadA...
November 17, 2016: Plant Molecular Biology
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
Shota Yamashita, Yoko Arakaki, Hiroko Kawai-Toyooka, Akira Noga, Masafumi Hirono, Hisayoshi Nozaki
BACKGROUND: Volvocine algae, which range from the unicellular Chlamydomonas to the multicellular Volvox with a germ-soma division of labor, are a model for the evolution of multicellularity. Within this group, the spheroidal colony might have evolved in two independent lineages: Volvocaceae and the goniacean Astrephomene. Astrephomene produces spheroidal colonies with posterior somatic cells. The feature that distinguishes Astrephomene from the volvocacean algae is lack of inversion during embryogenesis; the volvocacean embryo undergoes inversion after successive divisions to orient flagella toward the outside...
November 9, 2016: BMC Evolutionary Biology
W Moutier, L Duforêt-Gaurier, M Thyssen, H Loisel, X Mériaux, L Courcot, D Dessailly, S Alvain
This study presents an application of the Cytosense flow cytometer (CytoBuoy b.v., NL) for the analysis of the optical properties of phytoplankton cells. For the first time, the forward, sideward and backward cross sections (σFSC, σSSC and σ<sub>b<sub>b</sub> </sub>) were derived for two species morphologically different (Chlamydomonas concordia and Thalassiosira pseudonana). The objective of this work is to check the validity of the estimates before any applications in the frame of marine optics studies...
October 17, 2016: Optics Express
Girish Kumar Rasineni, Pek Chin Loh, Boon Hoe Lim
BACKGROUND: Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the chloroplast enzyme that fixes CO2 in photosynthesis, but the enzyme also fixes O2, which leads to the wasteful photorespiratory pathway. If we better understand the structure-function relationship of the enzyme, we might be able to engineer improvements. When the crystal structure of Chlamydomonas Rubisco was solved, four new posttranslational modifications were observed which are not present in other species...
November 3, 2016: Biochimica et Biophysica Acta
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
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