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Tristan Barbeyron, François Thomas, Valérie Barbe, Hanno Teeling, Chantal Schenowitz, Carole Dossat, Alexander Goesmann, Catherine Leblanc, Frank Oliver Glöckner, Mirjam Czjzek, Rudolf Amann, Gurvan Michel
The marine flavobacterium Zobellia galactanivorans Dsij(T) was isolated from a red alga and by now constitutes a model for studying algal polysaccharide bioconversions. We present an in-depth analysis of its complete genome and link it to physiological traits. Z. galactanivorans exhibited the highest gene numbers for glycoside hydrolases, polysaccharide lyases and carbohydrate esterases and the second highest sulfatase gene number in a comparison to 125 other marine heterotrophic bacteria (MHB) genomes. Its genome contains 50 Polysaccharide Utilization Loci, 22 of which contain sulfatase genes...
October 21, 2016: Environmental Microbiology
Takashi Nakada, Masaru Tomita
New strains of wall-less unicellular volvocalean flagellate were isolated from a freshwater environment in Japan. Observations of the alga, described here as Hapalochloris nozakii Nakada, gen. et sp. nov., were made under light, fluorescence, and electron microscopes. Each vegetative cell had two flagella, four contractile vacuoles, and a spirally furrowed cup-shaped chloroplast with an axial pyrenoid, and mitochondria located in the furrows. Based on the morphology, H. nozakii was distinguished from other known wall-less volvocalean flagellates...
October 21, 2016: Journal of Phycology
Jingyi Zhu, Tilo Mathes, Yusaku Hontani, Maxime T A Alexandre, Kee Chua Toh, Peter Hegemann, John T M Kennis
The two Light, Oxygen, and Voltage domains of phototropin are blue-light photoreceptor domains which control various functions in plants and green algae. The key step of the light-driven reaction is the formation of a photoadduct between its FMN chromophore and a conserved cysteine, where the canonical reaction proceeds through the FMN triplet state. Here, complete photoreaction mapping of CrLOV2 from Chlamydomonas reinhardtii phototropin and AsLOV2 from Avena sativa phototropin-1 was realized by ultrafast broadband spectroscopy from femtoseconds to microseconds...
October 21, 2016: Journal of Physical Chemistry Letters
Adeyemi S Adeleye, Arturo A Keller
The implications of engineered nanomaterials (ENMs) in the environment are often investigated using pristine particles. However, there are several biogenic and geogenic materials in natural waters that interact with and modify the surface of ENMs, thereby influencing their fate and effects. Here we studied the influence of soluble extracellular polymeric substances (sEPS) produced by freshwater and marine algae on the surface properties and fate of three commercial TiO2 nanoparticles (nTiO2) with different coatings...
October 21, 2016: Environmental Science & Technology
Lucía N Biruk, Juan Moretton, Alicia Fabrizio de Iorio, Cristian Weigandt, Jimena Etcheverry, Javier Filippetto, Anahí Magdaleno
The aim of this study was to investigate the parameters of chemical extraction associated with the detection of toxicity and genotoxicity in sediment sample extracts. Quantitative analysis of metals and polycyclic aromatic hydrocarbons (PAHs), together with a battery of four bioassays, was performed in order to evaluate the extraction efficiency of inorganic and organic toxicants. The extracts were carried out using two inorganic solvents, two organic solvents and two extraction methodologies, making a total of five extracts...
October 17, 2016: Ecotoxicology and Environmental Safety
Camille Detree, Gustavo Núñez-Acuña, Steven Roberts, Cristian Gallardo-Escárate
Saxitoxin (STX), a principal phycotoxin contributing to paralytic shellfish poisoning, is largely produced by marine microalgae of the genus Alexandrium. This toxin affects a wide range of species, inducing massive deaths in fish and other marine species. However, marine bivalves can resist and accumulate paralytic shellfish poisons. Despite numerous studies on the impact of STX in marine bivalves, knowledge regarding STX recognition at molecular level by benthic species remains scarce. Therefore, the aim of this study was to identify novel genes that interact with STX in the Chilean mussel Mytilus chilensis...
2016: PloS One
Pedro H C Pereira, Marcus Santos, Daniel L Lippi, Pedro Silva
Parrotfish are fundamental species in controlling algal phase-shifts and ensuring the resilience of coral reefs. Nevertheless, little is known on their ecological role in the south-western Atlantic Ocean. The present study analysed the ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae using behavioural observation and benthic composition analyses. We found a significant negative relationship between fish size and feeding rates for S. zelindae individuals...
2016: PeerJ
Liina Pajusalu, Georg Martin, Tiina Paalme, Arno Põllumäe
Anthropogenic carbon dioxide (CO2) emissions to the atmosphere are causing reduction in the global ocean pH, also known as ocean acidification. This change alters the equilibrium of different forms of dissolved inorganic carbon in seawater that macroalgae use for their photosynthesis. In the Baltic Sea, benthic macroalgae live in a highly variable environment caused by seasonality and rapid changes in meteorological conditions. The effect of increasing water CO2 concentration on the net photosynthesis of the red macroalgae Furcellaria lumbricalis (Hudson) Lamouroux was tested in short-term mesocosm experiments conducted in Kõiguste Bay (N Gulf of Riga) in June-July 2012 and 2013...
2016: PeerJ
Katrin Ochsenreither, Claudia Glück, Timo Stressler, Lutz Fischer, Christoph Syldatk
Polyunsaturated fatty acids (PUFAs) of the ω-3 and ω-6 class (e.g., α-linolenic acid, linoleic acid) are essential for maintaining biofunctions in mammalians like humans. Due to the fact that humans cannot synthesize these essential fatty acids, they must be taken up from different food sources. Classical sources for these fatty acids are porcine liver and fish oil. However, microbial lipids or single cell oils, produced by oleaginous microorganisms such as algae, fungi and bacteria, are a promising source as well...
2016: Frontiers in Microbiology
Najoua Akremi, Davie Cappoen, Roel Anthonissen, Abderrahman Bouraoui, Luc Verschaeve
: Dictyopteris membranacea, a species of Mediterranean brown algae, is believed to have potential pharmacological and nutritional applications. However, such potentials only make sense when devoid of any adverse health consequences. The present study should be seen in this context. It aimed at evaluating the genotoxicity and cytoxicity of its organic extract (F0) and semi purified fractions (F4, F5, and F6). Extracts were tested using the bacterial Vitotox(®) test and micronucleus assay in different concentrations (from 1...
July 2016: Pharmacognosy Magazine
Pierre D Thiriet, Antonio Di Franco, Adrien Cheminée, Paolo Guidetti, Olivier Bianchimani, Solène Basthard-Bogain, Jean-Michel Cottalorda, Hazel Arceo, Joan Moranta, Pierre Lejeune, Patrice Francour, Luisa Mangialajo
In Mediterranean subtidal rocky reefs, Cystoseira spp. (Phaeophyceae) form dense canopies up to 1 m high. Such habitats, called 'Cystoseira forests', are regressing across the entire Mediterranean Sea due to multiple anthropogenic stressors, as are other large brown algae forests worldwide. Cystoseira forests are being replaced by structurally less complex habitats, but little information is available regarding the potential difference in the structure and composition of fish assemblages between these habitats...
2016: PloS One
Shengwei Hou, Ulrike Pfreundt, Dan Miller, Ilana Berman-Frank, Wolfgang R Hess
Metatranscriptomic differential RNA-Seq (mdRNA-Seq) identifies the suite of active transcriptional start sites at single-nucleotide resolution through enrichment of primary transcript 5' ends. Here we analyzed the microbial community at 45 m depth at Station A in the northern Gulf of Aqaba, Red Sea, during 500 m deep mixing in February 2012 using mdRNA-Seq and a parallel classical RNA-Seq approach. We identified promoters active in situ for five different pico-planktonic genera (the SAR11 clade of Alphaproteobacteria, Synechococcus of Cyanobacteria, Euryarchaeota, Thaumarchaeota, and Micromonas as an example for picoeukaryotic algae), showing the applicability of this approach to highly diverse microbial communities...
October 19, 2016: Scientific Reports
Masaki Odahara, Yusuke Kobayashi, Toshiharu Shikanai, Yoshiki Nishimura
The chloroplast (cp) genome is organized as nucleoids that are dispersed throughout the cp stroma. Previously, a cp homolog of bacterial recombinase RecA (cpRECA) was shown to be involved in maintenance of cp genome integrity by repairing damaged cpDNA and by suppressing aberrant recombination between short dispersed repeats (SDRs) in the moss Physcomitrella patens. Here, overexpression and knockdown analysis of cpRECA in the green alga Chlamydomonas reinhardtii revealed that cpRECA was involved in cp nucleoid dynamics as well as having a role in maintaining cp genome integrity...
October 17, 2016: Plant Physiology
Maria Esther Perez-Perez, Stéphane D Lemaire, Jose L Crespo
Autophagy is a major catabolic pathway by which eukaryotic cells deliver unnecessary or damaged cytoplasmic material to the vacuole for its degradation and recycling in order to maintain cellular homeostasis. Control of autophagy has been associated with the production of reactive oxygen species in several organisms including plants and algae but the precise regulatory molecular mechanisms remain unclear. Here, we show that the ATG4 protease, an essential protein for autophagosome biogenesis, plays a central role for the redox regulation of autophagy in the model green alga Chlamydomonas reinhardtii...
October 17, 2016: Plant Physiology
Abdullah H A Dehwah, Samir Al-Mashharawi, Kim Choon Ng, Thomas M Missimer
An investigation of a sea water reverse osmosis desalination facility located in western Saudi Arabia has shown that aquifer treatment of the raw sea water provides a high degree of removal of natural organic matter (NOM) that causes membrane biofouling. The aquifer is a carbonate system that has a good hydraulic connection to the sea and 14 wells are used to induce sea water movement 400 to 450 m from the sea to the wells. During aquifer transport virtually all of the algae, over 90% of the bacteria, over 90% of the biopolymer fraction of NOM, and high percentages of the humic substance, building blocks, and some of the low molecular weight fractions of NOM are removed...
October 17, 2016: Ground Water
S Schiavo, N Duroudier, E Bilbao, M Mikolaczyk, J Schäfer, M P Cajaraville, S Manzo
In the last years, applications for silver nanoparticles (Ag NPs) continue to increase together with the concerns about their potential input and hazards in aquatic ecosystems, where microalgae are key organisms. The aim of the present study was to assess the relative sensitivity of three marine microalgae species with differences in cell wall composition/structure exposed to Poly N-vinyl-2-pirrolidone/Polyethyleneimine (PVP/PEI) coated 5nm Ag NPs and uncoated 47nm Ag NP. As limited attention has been paid to the role of coating agents in NP toxicity, the effect of PVP/PEI alone was also evaluated...
October 15, 2016: Science of the Total Environment
Baohu Dai, Jizhuang Wang, Ze Xiong, Xiaojun Zhan, Wei Dai, Chien-Cheng Li, Shien-Ping Feng, Jinyao Tang
Phototaxis is commonly observed in motile photosynthetic microorganisms. For example, green algae are capable of swimming towards a light source (positive phototaxis) to receive more energy for photosynthesis, or away from a light source (negative phototaxis) to avoid radiation damage or to hide from predators. Recently, with the aim of applying nanoscale machinery to biomedical applications, various inorganic nanomotors based on different propulsion mechanisms have been demonstrated. The only method to control the direction of motion of these self-propelled micro/nanomotors is to incorporate a ferromagnetic material into their structure and use an external magnetic field for steering...
October 17, 2016: Nature Nanotechnology
Lars Grossmann, Daniela Beisser, Christina Bock, Antonis Chatzinotas, Manfred Jensen, Angelika Preisfeld, Roland Psenner, Sven Rahmann, Sabina Wodniok, Jens Boenigk
Inferring ecosystem functioning and ecosystem services through inspections of the species inventory is a major aspect of ecological field studies. Ecosystem functions are often stable despite considerable species turnover. Using metatranscriptome analyses, we analyse a thus-far unparalleled freshwater dataset which comprises 21 mainland European freshwater lakes from the Sierra Nevada (Spain) to the Carpathian Mountains (Romania) and from northern Germany to the Apennines (Italy) and covers an altitudinal range from 38 m above sea level (a...
October 16, 2016: Molecular Ecology
Khawaja Muhammad Imran Bashir, Man-Gi Cho
Antibiotics are routinely used in microalgae culture screening, stock culture maintenance, and genetic transformation. By studying the effect of antibiotics on microalgae growth, we can estimate the least value to inhibit growth of undesired pathogens in algal culture. We studied the effect of kanamycin and tetracycline on the growth and photosynthetic activity of two chlorophyte microalgae, Dictyosphaerium pulchellum and Micractinium pusillum. We measured CFU mL(-1) on agar plates, optical density, fluorescence yields, and photosynthetic inhibition...
2016: BioMed Research International
Jordan M Casey, Andrew H Baird, Simon J Brandl, Mia O Hoogenboom, Justin R Rizzari, Ashley J Frisch, Christopher E Mirbach, Sean R Connolly
Removal of predators is often hypothesized to alter community structure through trophic cascades. However, despite recent advances in our understanding of trophic cascades, evidence is often circumstantial on coral reefs because fishing pressure frequently co-varies with other anthropogenic effects, such as fishing for herbivorous fishes and changes in water quality due to pollution. Australia's outer Great Barrier Reef (GBR) has experienced fishing-induced declines of apex predators and mesopredators, but pollution and targeting of herbivorous fishes are minimal...
October 15, 2016: Oecologia
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