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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
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
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
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
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)
Stefano Magni, Antonella Succurro, Alexander Skupin, Oliver Ebenhöh
Global warming exposes plants to severe heat stress, with consequent crop yield reduction. Organisms exposed to high temperature stresses typically protect themselves with a heat shock response (HSR), where accumulation of unfolded proteins initiates the synthesis of heat shock proteins through the heat shock transcription factor HSF1. While the molecular mechanisms are qualitatively well characterized, our quantitative understanding of the underlying dynamics is still very limited. Here, we study the dynamics of HSR in the photosynthetic model organism Chlamydomonas reinhardtii with a data-driven mathematical model of HSR...
May 2018: Journal of the Royal Society, Interface
Sebastian Proost, Marek Mutwil
The recent accumulation of gene expression data in the form of RNA sequencing creates unprecedented opportunities to study gene regulation and function. Furthermore, comparative analysis of the expression data from multiple species can elucidate which functional gene modules are conserved across species, allowing the study of the evolution of these modules. However, performing such comparative analyses on raw data is not feasible for many biologists. Here, we present CoNekT (Co-expression Network Toolkit), an open source web server, that contains user-friendly tools and interactive visualizations for comparative analyses of gene expression data and co-expression networks...
May 1, 2018: Nucleic Acids Research
Camilla Ferrari, Sebastian Proost, Colin Ruprecht, Marek Mutwil
Phytoplankton consists of autotrophic, photosynthesizing microorganisms that are a crucial component of freshwater and ocean ecosystems. However, despite being the major primary producers of organic compounds, accounting for half of the photosynthetic activity worldwide and serving as the entry point to the food chain, functions of most of the genes of the model phytoplankton organisms remain unknown. To remedy this, we have gathered publicly available expression data for one chlorophyte, one rhodophyte, one haptophyte, two heterokonts and four cyanobacteria and integrated it into our PlaNet (Plant Networks) database, which now allows mining gene expression profiles and identification of co-expressed genes of 19 species...
April 30, 2018: Nucleic Acids Research
Zhang Yizhi, Launay Hélène, Schramm Antoine, Lebrun Régine, Gontero Brigitte
The content of intrinsically disordered protein (IDP) is related to organism complexity, evolution, and regulation. In the Plantae, despite their high complexity, experimental investigation of IDP content is lacking. We identified by mass spectrometry 682 heat-resistant proteins from the green alga, Chlamydomonas reinhardtii. Using a phosphoproteome database, we found that 331 of these proteins are targets of phosphorylation. We analyzed the flexibility propensity of the heat-resistant proteins and their specific features as well as those of predicted IDPs from the same organism...
May 1, 2018: Scientific Reports
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