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Remedios Guzmán-Guillén, Alexandre Campos, Joana Machado, Marisa Freitas, Joana Azevedo, Edgar Pinto, Agostinho Almeida, Ana M Cameán, Vitor Vasconcelos
Natural toxins produced by freshwater cyanobacteria, such as cylindrospermopsin, have been regarded as an emergent environmental threat. Despite the risks for food safety, the impact of these water contaminants in agriculture is not yet fully understood. Carrots (Daucus carota) are root vegetables, extensively consumed worldwide with great importance for human nourishment and economy. It is, therefore, important to evaluate the possible effects of using water contaminated with cyanotoxins on carrot cultivation...
October 21, 2016: Ecotoxicology
Yunpeng Wang, Lei Chen, Weiwen Zhang
BACKGROUND: 3-hydroxypropionic acid (3-HP) is an important platform chemical with a wide range of applications. In our previous study, the biosynthetic pathway of 3-HP was constructed and optimized in cyanobacterium Synechocystis sp. PCC 6803, which led to 3-HP production directly from CO2 at a level of 837.18 mg L(-1) (348.8 mg/g dry cell weight). As the production and accumulation of 3-HP in cells affect cellular metabolism, a better understanding of cellular responses to 3-HP synthesized internally in Synechocystis will be important for further increasing 3-HP productivity in cyanobacterial chassis...
2016: Biotechnology for Biofuels
Diane M Orihel, David W Schindler, Nathaniel C Ballard, Lindsey R Wilson, Rolf D Vinebrooke
The effects of reducing nutrient inputs to lakes and reservoirs are often delayed by hysteresis resulting from internal phosphorus (P) loading from sediments. Consequently, controlling harmful algal blooms (HABs) in many eutrophic ecosystems requires additional management to improve water quality. We manipulated iron (Fe) concentrations in a hypereutrophic lake to determine if Fe amendment would suppress HABs by inhibiting P release from sediments. Our experiment consisted of 15 in situ mesocosms, 12 of which each received a different dose of Fe (ranging from 2 to 225 g/m(2) ); the remaining three were unmanipulated to serve as controls...
July 2016: Ecological Applications: a Publication of the Ecological Society of America
Shoubing Wang, Ziran Xu
Increased eutrophication in the recent years has resulted in considerable research focus on identification of methods for preventing cyanobacterial blooms that are rapid and efficient. The objectives of this study were to investigate the effects of dihydroartemisinin and artemether on the growth of Microcystis aeruginosa and to elucidate its mode of action. Variations in cell density, chlorophyll a, soluble protein, malondialdehyde, extracellular alkaline phosphatase activity (APA), and chlorophyll fluorescence parameters (Fv/Fm, ΦPSII, ETR, rapid light curves, fast chlorophyll fluorescence curves on fluorescence intensity, and relative variable fluorescence) were evaluated by lab-cultured experiments...
2016: PloS One
J Machado, J Azevedo, M Freitas, E Pinto, A Almeida, V Vasconcelos, A Campos
Toxic cyanobacterial blooms are often observed in freshwaters and may reflect the increased eutrophication of these environments and alterations in climate. Cyanotoxins, such as microcystins (MCs), are an effective threat to many life forms, ranging from plants to humans. Despite the research conducted to date on cyanotoxins, the risks associated to the use of contaminated water in agriculture require further elucidation. To tackle this aim, a research was conducted with the root-vegetable Daucus carota. The specific aims of this work were the following: (i) to evaluate the effects of MC-LR on the plant growth and photosynthesis; (ii) to evaluate the nutritional quality of carrot roots; and (iii) to measure bioaccumulation...
October 18, 2016: Environmental Science and Pollution Research International
Masaaki Sugiyama, Hirokazu Yagi, Kentaro Ishii, Lionel Porcar, Anne Martel, Katsuaki Oyama, Masanori Noda, Yasuhiro Yunoki, Reiko Murakami, Rintaro Inoue, Nobuhiro Sato, Yojiro Oba, Kazuki Terauchi, Susumu Uchiyama, Koichi Kato
The molecular machinery of the cyanobacterial circadian clock consists of three proteins: KaiA, KaiB, and KaiC. Through interactions among the three Kai proteins, the phosphorylation states of KaiC generate circadian oscillations in vitro in the presence of ATP. Here, we characterized the complex formation between KaiB and KaiC using a phospho-mimicking mutant of KaiC, which had an aspartate substitution at the Ser431 phosphorylation site and exhibited optimal binding to KaiB. Mass-spectrometric titration data showed that the proteins formed a complex exclusively in a 6:6 stoichiometry, indicating that KaiB bound to the KaiC hexamer with strong positive cooperativity...
October 18, 2016: Scientific Reports
Huacheng Xu, Changming Yang, Helong Jiang
The stability/aggregation propensity of inorganic colloids in eutrophic shallow lakes is of great essence in governing the water transparency and contaminant behavior. In this study, time-resolved dynamic light scattering was employed to investigate the aggregation kinetics of Al2O3 inorganic colloids over a wide range of cyanobacterial extracellular polymeric substance (EPS) concentrations in the absence and presence of electrolyte cations. The results showed that EPS adsorption alone greatly decreased the hydrodynamic diameters of colloidal particles, whose stability behavior followed closely the predictions of the classical DLVO theory...
October 8, 2016: Water Research
Yuanyuan Chen, Jian Li, Jin Wei, Atufa Kawan, Li Wang, Xuezhen Zhang
Cyanobacterial blooms and their associated toxins pose a great threat to human beings. The situation is even worse for those whose drinking water source is a cyanotoxin-polluted water body. Therefore, efficient and safe treatments urgently need to be developed. The present study verified the application of vitamin C on the inhibition of toxic Microcystis aeruginosa. Our results showed that vitamin C drove the Fenton reaction and significantly sterilized cultures of M. aeruginosa. The algicidal activity of vitamin C was dependent on its involvement in iron (Fe) metabolism...
October 6, 2016: Journal of Hazardous Materials
Isabella Bertani, Cara E Steger, Daniel R Obenour, Gary L Fahnenstiel, Thomas B Bridgeman, Thomas H Johengen, Michael J Sayers, Robert A Shuchman, Donald Scavia
Cyanobacteria blooms are a major environmental issue worldwide. Our understanding of the biophysical processes driving cyanobacterial proliferation and the ability to develop predictive models that inform resource managers and policy makers rely upon the accurate characterization of bloom dynamics. Models quantifying relationships between bloom severity and environmental drivers are often calibrated to an individual set of bloom observations, and few studies have assessed whether differences among observing platforms could lead to contrasting results in terms of relevant bloom predictors and their estimated influence on bloom severity...
October 12, 2016: Science of the Total Environment
Bradley W Abramson, Benjamin Kachel, David M Kramer, Daniel C Ducat
In plants, a limited capacity to utilize or export the end products of the Calvin Benson cycle (CB) from photosynthetically-active source cells to non-photosynthetic sink cells can result in reduced carbon capture, photosynthetic electron transport (PET) and lowered photochemical efficiency. The downregulation of photosynthesis caused by reduced capacity to utilize photosynthate has been termed "sink limitation". Recently, several cyanobacterial and algal strains engineered to over-produce target metabolites have exhibited increased photochemistry suggesting possible source-sink regulatory mechanisms may be involved...
October 13, 2016: Plant & Cell Physiology
Natalie C Sadler, Hans C Bernstein, Matthew R Melnicki, Moiz A Charania, Eric A Hill, Lindsey N Anderson, Matthew E Monroe, Richard D Smith, Alexander S Beliaev, Aaron T Wright
: Photobiologically synthesized hydrogen (H2) gas is carbon-neutral to produce and clean to combust, making it an ideal biofuel. Cyanothece sp. ATCC 51142 is a cyanobacterium capable of performing simultaneous oxygenic photosynthesis and H2 production, a highly perplexing phenomenon because H2 evolving enzymes are O2-sensitive. We employed a systems-level in vivo chemoproteomic profiling approach to explore the cellular dynamics of protein thiol redox, and how thiol redox mediates the function of the dinitrogenase NifHDK, an enzyme complex capable of aerobic hydrogenase activity...
October 14, 2016: Applied and Environmental Microbiology
Shu Harn Te, Boon Fei Tan, Janelle R Thompson, Karina Yew-Hoong Gin
Genomes of two filamentous benthic cyanobacteria were obtained from cocultures obtained from two freshwater lakes. The cultures were obtained by first growing cyanobacterial trichome on solid medium, followed by subculturing in freshwater media. Subsequent shotgun sequencing, de novo assembly, and genomic binning yielded almost complete genomes of Oscillatoriales USR 001 and Nostoc sp. MBR 210.
October 13, 2016: Genome Announcements
Ramsy Agha, Manja Saebelfeld, Christin Manthey, Thomas Rohrlack, Justyna Wolinska
Parasites are rarely included in food web studies, although they can strongly alter trophic interactions. In aquatic ecosystems, poorly grazed cyanobacteria often dominate phytoplankton communities, leading to the decoupling of primary and secondary production. Here, we addressed the interface between predator-prey and host-parasite interactions by conducting a life-table experiment, in which four Daphnia galeata genotypes were maintained on quantitatively comparable diets consisting of healthy cyanobacteria or cyanobacteria infected by a fungal (chytrid) parasite...
October 13, 2016: Scientific Reports
Ratna Prabha, Dhananjaya P Singh, Swati Sinha, Khurshid Ahmad, Anil Rai
With the increasing accumulation of genomic sequence information of prokaryotes, the study of codon usage bias has gained renewed attention. The purpose of this study was to examine codon selection pattern within and across cyanobacterial species belonging to diverse taxonomic orders and habitats. We performed detailed comparative analysis of cyanobacterial genomes with respect to codon bias. Our analysis reflects that in cyanobacterial genomes, A- and/or T-ending codons were used predominantly in the genes whereas G- and/or C-ending codons were largely avoided...
October 9, 2016: Marine Genomics
Yu Nakashima, Yoko Egami, Miki Kimura, Toshiyuki Wakimoto, Ikuro Abe
Sponge metagenomes are a useful platform to mine cryptic biosynthetic gene clusters responsible for production of natural products involved in the sponge-microbe association. Since numerous sponge-derived bioactive metabolites are biosynthesized by the symbiotic bacteria, this strategy may concurrently reveal sponge-symbiont produced compounds. Accordingly, a metagenomic analysis of the Japanese marine sponge Discodermia calyx has resulted in the identification of a hybrid type I polyketide synthase-nonribosomal peptide synthetase gene (kas)...
2016: PloS One
Kazuyoshi Murata, Sayuri Hagiwara, Yoshitaka Kimori, Yasuko Kaneko
Some cyanobacteria exhibit compaction of DNA in synchrony with their circadian rhythms accompanying cell division. Since the structure is transient, it has not yet been described in detail. Here, we successfully visualize the ultrastructure of compacted DNA in the cyanobacterium Synechococcus elongatus PCC 7942 under rigorous synchronized cultivation by means of high-voltage cryo-electron tomography. In 3D reconstructions of rapidly frozen cells, the compacted DNA appears as an undulating rod resembling a eukaryotic condensed chromosome...
October 12, 2016: Scientific Reports
Kevin C Lee, Stephen D J Archer, Rachel H Boyle, Donnabella C Lacap-Bugler, Jayne Belnap, Stephen B Pointing
A common feature of microbial colonization in deserts is biological soil crusts (BSCs), and these comprise a complex community dominated by Cyanobacteria. Rock substrates, particularly sandstone, are also colonized by microbial communities. These are separated by bare sandy soil that also supports microbial colonization. Here we report a high-throughput sequencing study of BSC and cryptoendolith plus adjacent bare soil communities in the Colorado Plateau Desert, Utah, USA. Bare soils supported a community with low levels of recoverable DNA and high evenness, whilst BSC yielded relatively high recoverable DNA, and reduced evenness compared to bare soil due to specialized crust taxa...
2016: Frontiers in Microbiology
Stephanie L Olson, Christopher T Reinhard, Timothy W Lyons
The redox landscape of Earth's ocean-atmosphere system has changed dramatically throughout Earth history. Although Earth's protracted oxygenation is undoubtedly the consequence of cyanobacterial oxygenic photosynthesis, the relationship between biological O2 production and Earth's redox evolution remains poorly understood. Existing models for Earth's oxygenation cannot adequately explain the nearly 2.5 billion years delay between the origin of oxygenic photosynthesis and the oxygenation of the deep ocean, in large part owing to major deficiencies in our understanding of the coevolution of O2 and Earth's key biogeochemical cycles (e...
2016: Frontiers in Microbiology
Yi Li, Lei Liu, Yanting Xu, Li Ping, Kun Zhang, Xiaobing Jiang, Tianling Zheng, Hailei Wang
Microcystis aeruginosa is a cyanobacterial bloom-causing species and has been considered a serious human health and biological safety threat. In this study, algicidal bacterium h10 showed high algicidal effects on M. aeruginosa 7820, and strain h10 was confirmed to belong to genus Exiguobacterium, for which name Exiguobacterium sp. h10 is proposed. Algicidal activity and mode analysis revealed that supernatant rather than bacterial cells was responsible for showing algicidal activity, which indicated that the algicidal mode of strain h10 is an indirect attack through producing algicidal substances...
October 7, 2016: Letters in Applied Microbiology
Masahiro Okada, Tomotoshi Sugita, Kohei Akita, Yu Nakashima, Tian Tian, Chang Li, Takahiro Mori, Ikuro Abe
Prenylation is a key post-translational reaction to increase the structural diversity and bioactivity of peptides and proteins. Until now, only one post-translational modification enzyme, ComQ, has been identified to mediate the prenylation of a tryptophan residue in ribosomally synthesized peptides. Here, we report the in vitro characterization of KgpF, a novel prenyltransferase which transfers dimethylallyl moieties to tryptophan residues during kawaguchipeptin A biosynthesis. The stereospecific prenylation by KgpF was determined by a combination of in vitro dimethylallylation of Fmoc-tryptophan by KgpF and chemical synthesis of dimethylallylated Fmoc-tryptophan diastereomers...
October 12, 2016: Organic & Biomolecular Chemistry
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