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Han Sun, Xuemei Mao, Tao Wu, Yuanyuan Ren, Feng Chen, Bin Liu
Revenues of carotenoid and lipid biosynthesis under excess light and nitrogen starvation were firstly analyzed for the increased biomass value through carbon metabolism analysis. The results suggested excess light and nitrogen starvation resulted in carbon partitioning among protein, starch, lipid and carotenoid. Nitrogen starvation promoted more cellular lipid content than excess light, while excess light promoted carotenoid and polyunsaturated fatty acid accumulation. In the molecular level, the stresses redirected carbon skeletons into the central metabolite of pyruvate and oriented into starch and lipid as the primary and secondary carbon storage, respectively...
May 10, 2018: Bioresource Technology
Rishiram Ramanan, Quynh-Giao Tran, Dae-Hyun Cho, Jae-Eun Jeong, Byung-Hyuk Kim, Sang-Yoon Shin, Sae-Hae Choi, Kwang-Hyeon Liu, Dae-Soo Kim, Seon-Jin Lee, Jose L Crespo, Hee-Gu Lee, Hee-Mock Oh, Hee-Sik Kim
Algae undergo a complete metabolic transformation under stress by arresting cell growth, inducing autophagy, and hyper-accumulating biofuel precursors such as triacylglycerols and starch. However, the regulatory mechanisms behind this stress-induced transformation are still unclear. Here, we use biochemical, mutational, and 'omics' approaches to demonstrate that phosphatidylinositol 3-kinase (PI3K) signaling mediates the homeostasis of energy molecules and influences carbon metabolism in algae. In Chlamydomonas reinhardtii, the inhibition and knockdown (KD) of algal class III PI3K led to significantly decreased cell growth, altered cell morphology, and higher lipid and starch contents...
May 16, 2018: Plant Physiology
Lubna V Richter, Huijun Yang, Mohammad Yazdani, Maureen R Hanson, Beth A Ahner
Background: We investigated strategies to improve foreign protein accumulation in the chloroplasts of the model algae Chlamydomonas reinhardtii and tested the outcome in both standard culture conditions as well as one pertinent to algal biofuel production. The downstream box (DB) of the TetC or NPTII genes, the first 15 codons following the start codon, was N -terminally fused to the coding region of cel6A , an endoglucanase from Thermobifida fusca . We also employed a chimeric regulatory element, consisting of the 16S rRNA promoter and the atpA 5'UTR, previously reported to enhance protein expression, to regulate the expression of the TetC- cel6A gene...
2018: Biotechnology for Biofuels
Lenka Procházková, Daniel Remias, Andreas Holzinger, Tomáš Řezanka, Linda Nedbalová
Based on analyses of multiple molecular markers (18S rDNA, ITS1, ITS2 rDNA, rbc L), an alga that causes red snow on the melting ice cover of a high-alpine lake in the High Tatras (Slovakia) was shown to be identical with Chlainomonas sp. growing in a similar habitat in the Tyrolean Alps (Austria). Both populations consisted mostly of smooth-walled quadriflagellates. They occurred in slush, and shared similar photosynthetic performances (photoinhibition above 1300 µmol photons m-2 s-1 ), very high levels of polyunsaturated fatty acids (PUFA, 64% and 74% respectively) and abundant astaxanthin accumulation, comparable to the red spores of Chlamydomonas nivalis (Bauer) Wille...
2018: European Journal of Phycology
Mahshid Samadani, David Dewez
In this study, the accumulation and toxicity effect of 1-7 μM of Hg was determined during 24-72 h on two strains of Chlamydomonas reinhardtii, CC-125 and CC-503 as a cell wall-deficient mutant, by monitoring the growth rate and the maximum quantum yield of Photosystem II. In addition, the level of extracytoplasmic polyphosphates (polyP related to the cell wall) was determined to understand the polyP physiological role in Hg-treated algal cells. The results showed that the polyP level was higher in the strain CC-125 compared to CC-503...
May 10, 2018: Environmental Pollution
Jiaying Wang, Jingpeng Wang, Jinsong Liu, Jianzhi Li, Lihong Zhou, Huanxin Zhang, Jianteng Sun, Shulin Zhuang
The phenolic compounds have posed public concern for potential threats to human health and ecosystem. Tert-butylphenols (TBPs), as one group of emerging contaminants, showed potential endocrine disrupting effects and aquatic toxicities. In the present study, we detected concentrations of 2,4-DTBP ranging from <0.001 to 0.057 μg/L (detection limit: 0.001 μg/L) in drinking water source from the Qiantang River in East China in April 2016. The endocrine disrupting effects of 2-TBP, 2,4-DTBP and 2,6-DTBP toward human estrogen receptor α (ERα), androgen receptor (AR) and thyroid hormone receptor β (TRβ) were evaluated using human recombinant two-hybrid yeast bioassay...
May 9, 2018: Environmental Pollution
Yazhi Gao, Wei Liu, Xiaoxiong Wang, Lihua Yang, Su Han, Shiguo Chen, Reto Jörg Strasser, Bernal E Valverde, Sheng Qiang
The effects of four phytotoxins usnic acid (UA), salicylic acid (SA), cinnamic acid (CA) and benzoic acid (BA) on photosynthesis of Chlamydomonas reinhardtii were studied in vivo to identify and localise their initial action sites on two photosystems. Our experimental evidence shows that the four phytotoxins have multiple targets in chloroplasts, which mainly lie in photosystem II (PSII), not photosystem I (PSI). They share an original action site by blocking electron transport beyond QA (primary plastoquinone acceptor) at PSII acceptor side since a fast increase of the J-step level is the greatest change in chlorophyll a fluorescence induction kinetics OJIP in C...
May 4, 2018: Plant Physiology and Biochemistry: PPB
Yuting Wang, Xiaoshan Zhuang, Meirong Chen, Zhiyong Zeng, Xiaoqi Cai, Hui Li, Zhangli Hu
Background: Hydrogen photoproduction from green microalgae is regarded as a promising alternative solution for energy problems. However, the simultaneous oxygen evolution from microalgae can prevent continuous hydrogen production due to the hypersensitivity of hydrogenases to oxygen. Sulfur deprivation can extend the duration of algal hydrogen production, but it is uneconomical to alternately culture algal cells in sulfur-sufficient and sulfur-deprived media. Results: In this study, we developed a novel way to simulate sulfur-deprivation treatment while constantly maintaining microalgal cells in sulfur-sufficient culture medium by overexpressing an endogenous microRNA (miR1166...
2018: Biotechnology for Biofuels
Michal Breker, Kristi Lieberman, Frederick Cross
We generated a large collection of temperature-sensitive lethal mutants in the unicellular green alga Chlamydomonas reinhardtii, focusing on mutations specifically affecting cell cycle regulation. We used UV mutagenesis and robotically assisted phenotypic screening to isolate candidates. To overcome the bottleneck at the critical step of molecular identification of the causative mutation ('driver'), we developed MAPS-SEQ (Meiosis-Assisted Purifying Selection Sequencing), a multiplexed genetic/bioinformatics strategy...
May 9, 2018: Plant Cell
Seongjoon Kang, Obed W Odom, Candice L Malone, Saravanan Thangamani, David L Herrin
Chlamydomonas reinhardtii ( Chlamydomonas ) strains that are toxic to mosquito larvae because they express chloroplast transgenes that are based on the mosquitocidal proteins of Bacillus thuringiensis subsp. israelensis (Bti) could be very useful in mosquito control. Chlamydomonas has several advantages for this approach, including genetic controls not generally available with industrial algae. The Bti toxin is produced by sporulating bacteria and has been used for mosquito control for >30 years without creating highly resistant mosquito populations...
May 8, 2018: Biology
Marina Cvetkovska, Beth Szyszka-Mroz, Marc Possmayer, Paula Pittock, Gilles Lajoie, David R Smith, Norman P A Hüner
The objective of this work was to characterize photosynthetic ferredoxin from the Antarctic green alga Chlamydomonas sp. UWO241, a key enzyme involved in distributing photosynthetic reducing power. We hypothesize that ferredoxin possesses characteristics typical of cold-adapted enzymes, namely increased structural flexibility and high activity at low temperatures, accompanied by low stability at moderate temperatures. To address this objective, we purified ferredoxin from UWO241 and characterized the temperature dependence of its enzymatic activity and protein conformation...
May 8, 2018: New Phytologist
Jiashun Cao, Ruixue Jiang, Jiaqin Wang, Jiayu Sun, Qian Feng, Zhilin Zhao, Guodong Chen, Changren Zhou, Erqin Yin
Our research investigated the hormesis effect of cefradine on the specific growth rates (μ) of single-celled algae (Chlamydomonas reinhardtii) from aqueous solutions. We found the specific growth rate of C. reinhardtii slightly increased with cefradine concentrations within the range 0.5-10 mg/L. Effects of algae density, initial solution pH, and temperature on the adsorption batch assays were investigated. The optimum conditions for cefradine adsorption occurred at a density of 5 × 106 algae cells/mL, a solution pH of 7...
May 3, 2018: Ecotoxicology and Environmental Safety
Ricardo Saavedra, Raúl Muñoz, María Elisa Taboada, Marisol Vega, Silvia Bolado
This work represents a comparative uptake study of the toxic elements arsenic, boron, copper, manganese and zinc in monometallic and multimetallic solutions by four green microalgae species (Chlamydomonas reinhardtii, Chlorella vulgaris, Scenedesmus almeriensis and an indigenous Chlorophyceae spp.), evaluating the effect of pH and contact time. Maximum removal efficiencies for each toxic element were 99.4% for Mn (C. vulgaris, pH 7.0, 3 h), 91.9% for Zn (Chlorophyceae spp., pH 5.5, 3 h), 88% for Cu (Chlorophyceae spp...
April 26, 2018: Bioresource Technology
Natalie Heimerl, Elisabeth Hommel, Martin Westermann, Doreen Meichsner, Martin Lohr, Christian Hertweck, Arthur R Grossman, Maria Mittag, Severin Sasso
Polyketide synthases (PKSs) occur in many bacteria, fungi and plants. They are highly versatile enzymes involved in the biosynthesis of a large variety of compounds including antimicrobial agents, polymers associated with bacterial cell walls and plant pigments. While harmful algae are known to produce polyketide toxins, sequences of the genomes of non-toxic algae, including those of many green-algal species, have surprisingly revealed the presence of genes encoding type I PKSs. The genome of the model alga Chlamydomonas reinhardtii (Chlorophyta) contains a single type I PKS gene, designated PKS1 (Cre10...
May 4, 2018: Plant Journal: for Cell and Molecular Biology
Yeonju Na, Ha-Nul Lee, Jiwoong Wi, Won-Joong Jeong, Dong-Woog Choi
Pyropia are commercially valuable marine red algae that grow in the intertidal zone. They are extremely tolerant to desiccation stress. We have previously identified and reported desiccation response genes (DRGs) based on transcriptome analysis of P. tenera. Among them, PtDRG1 encodes a polypeptide of 22.6 kDa that is located in the chloroplast. PtDRG1 does not share sequence homology with any known gene deposited in public database. Transcription of PtDRG1 gene was upregulated by osmotic stress induced by mannitol or H2 O2 as well as desiccation stress, but not by heat...
May 4, 2018: Marine Biotechnology
Fernando Puente-Sánchez, Silvia Díaz, Vanessa Penacho, Angeles Aguilera, Sanna Olsson
To better understand heavy metal tolerance in Chlamydomonas acidophila, an extremophilic green alga, we assembled its transcriptome and measured transcriptomic expression before and after Cd exposure in this and the neutrophilic model microalga Chlamydomonas reinhardtii. Genes possibly related to heavy metal tolerance and detoxification were identified and analyzed as potential key innovations that enable this species to live in an extremely acid habitat with high levels of heavy metals. In addition we provide a data set of single orthologous genes from eight green algal species as a valuable resource for comparative studies including eukaryotic extremophiles...
April 27, 2018: Aquatic Toxicology
Mahmoud R Fassad, Amelia Shoemark, Pierrick le Borgne, France Koll, Mitali Patel, Mellisa Dixon, Jane Hayward, Charlotte Richardson, Emily Frost, Lucy Jenkins, Thomas Cullup, Eddie M K Chung, Michel Lemullois, Anne Aubusson-Fleury, Claire Hogg, David R Mitchell, Anne-Marie Tassin, Hannah M Mitchison
Primary ciliary dyskinesia (PCD) is a genetically and phenotypically heterogeneous disorder characterized by destructive respiratory disease and laterality abnormalities due to randomized left-right body asymmetry. PCD is mostly caused by mutations affecting the core axoneme structure of motile cilia that is essential for movement. Genes that cause PCD when mutated include a group that encode proteins essential for the assembly of the ciliary dynein motors and the active transport process that delivers them from their cytoplasmic assembly site into the axoneme...
May 3, 2018: American Journal of Human Genetics
Yizhi Zhang, Hélène Launay, Fan Liu, Régine Lebrun, Brigitte Gontero
The critical and ubiquitous enzyme adenylate kinase (ADK) catalyzes the nucleotide phosphoryl exchange reaction: 2ADP ↔ ATP + AMP. The ADK3 in the chloroplasts of the green alga Chlamydomonas reinhardtii, bears an unusual C-terminal extension that is similar to the C-terminal end of the intrinsically disordered protein CP12. In this study, we report that this enzyme, when oxidized but not when reduced, is able to interact with the chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) forming a stable complex as shown by native electrophoresis and mass spectrometry...
May 4, 2018: FEBS Journal
Zhen Yu, Huiling Wei, Rui Hao, Huashuo Chu, Yi Zhu
Cadmium (Cd) is a nonessential and toxic trace element widely existing in waters through various anthropogenic activities such as mining and waste disposal. The physiological responses of aquatic organisms to long-term Cd exposure at environmentally relevant concentrations are still not well explored. In the present study, two strains of unicellular green algae Chlamydomonas reinhardtii, a walled strain CC125 and a wall-less strain CC406 were selected to investigate the physiological changes of aquatic organisms after long-term Cd exposure at environmentally relevant concentrations (4...
May 4, 2018: Environmental Science. Processes & Impacts
Brian Nguyen, Percival J Graham, Chelsea M Rochman, David Sinton
A platform compatible with microtiter plates to parallelize environmental treatments to test the complex impacts of multiple stressors, including parameters relevant to climate change and point source pollutants is developed. This platform leverages (1) the high rate of purely diffusive gas transport in aerogels to produce well-defined centimeter-scale gas concentration gradients, (2) spatial light control, and (3) established automated liquid handling. The parallel gaseous, aqueous, and light control provided by the platform is compatible with multiparameter experiments across the life sciences...
April 2018: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
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