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https://www.readbyqxmd.com/read/28803467/not-gate-genetic-circuits-to-control-gene-expression-in-cyanobacteria
#1
Arnaud Taton, Amy T Ma, Mizuho Ota, Susan Golden, James W Golden
To downregulate gene expression in cyanobacteria, we constructed NOT gate genetic circuits using orthogonal promoters and their cognate repressors regulated translationally by synthetic riboswitches. Four NOT gates were tested and characterized in five cyanobacterial strains using fluorescent reporter-gene assays. In comparison to alternative systems used to downregulate gene expression in cyanobacteria, these NOT gates performed well, reducing YFP reporter expression by 4 to 50-fold. We further evaluated these NOT gates by controlling the expression of the ftsZ gene, which encodes a prokaryotic tubulin homolog that is required for cell division and is essential for Synechococcus elongatus PCC 7942...
August 14, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28794262/super-resolution-microscopy-of-the-%C3%A3-carboxysome-reveals-a-homogenous-matrix
#2
Matthew J Niederhuber, Talley J Lambert, Clarence Yapp, Pamela A Silver, Jessica K Polka
Carbon fixation in cyanobacteria makes a major contribution to the global carbon cycle. The cyanobacterial carboxysome is a proteinaceous microcompartment that protects and concentrates the carbon-fixing enzyme RuBisCO in a paracrystalline lattice, making it possible for these organisms to fix CO2 from the atmosphere. The protein responsible for the organization of this lattice in beta-type carboxysomes of the freshwater cyanobacterium Synechococcus elongatus, CcmM, occurs in two isoforms thought to localize differentially within the carboxysome matrix...
August 9, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28790992/the-cyanobacteria-dominated-sponge-dactylospongia-elegans-in-the-south-china-sea-prokaryotic-community-and-metagenomic-insights
#3
Zhao-Ming Gao, Guo-Wei Zhou, Hui Huang, Yong Wang
The South China Sea is a special reservoir of sponges of which prokaryotic communities are less studied. Here, a new record of the sponge Dactylospongia elegans is reported near the coast of Jinqing Island in the South China Sea, and its prokaryotic community is comprehensively investigated. Sponge specimens displayed lower microbial diversity compared with surrounding seawater. At the phylum level, prokaryotic communities were consistently dominated by Proteobacteria, followed by Cyanobacteria, Chloroflexi, Acidobacteria, Actinobacteria, Gemmatimonadetes, Thaumarchaeota, and Poribacteria...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28769912/xanthomonas-citri-minc-oscillates-from-pole-to-pole-to-ensure-proper-cell-division-and-shape
#4
André S G Lorenzoni, Giordanni C Dantas, Tessa Bergsma, Henrique Ferreira, Dirk-Jan Scheffers
Xanthomonas citri (Xac) is the causal agent of citrus canker, a disease that affects citrus crops and causes economic impact worldwide. To further characterize cell division in this plant pathogen, we investigated the role of the protein MinC in cell division, chromosome segregation, and peptidoglycan incorporation by deleting the gene minC using allele exchange. Xac with minC deleted exhibited the classic Δmin phenotype observed in other bacteria deleted for min components: minicells and short filamentation...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28762000/production-of-%C3%AF-3-fatty-acids-in-marine-cyanobacterium-synechococcus-sp-strain-nkbg-15041c-via-genetic-engineering
#5
Tomoko Yoshino, Natsumi Kakunaka, Yue Liang, Yasuhito Ito, Yoshiaki Maeda, Tatsuhiro Nomaguchi, Tadashi Matsunaga, Tsuyoshi Tanaka
Omega-3 fatty acids (ω3 FAs) have attracted attention because they have various health benefits for humans. Fish oils are currently major sources of ω3 FAs, but a sustainable supply of ω3 FAs based on fish oils is problematic because of the increasing demand. In this study, the production potential of a genetically engineered marine cyanobacterium, Synechococcus sp. strain NKBG 15041c, was examined as an alternative source of ω3 FAs. A change in fatty acid composition of this cyanobacterium was successfully induced by the expression of a heterologous Δ6-desaturase, and the transformants synthesized stearidonic acid, which the wild type cannot produce...
August 1, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28755724/effects-of-elevated-co2-on-phytoplankton-community-biomass-and-species-composition-during-a-spring-phaeocystis-spp-bloom-in-the-western-english-channel
#6
Matthew Keys, Gavin Tilstone, Helen S Findlay, Claire E Widdicombe, Tracy Lawson
A 21-year time series of phytoplankton community structure was analysed in relation to Phaeocystis spp. to elucidate its contribution to the annual carbon budget at station L4 in the western English Channel (WEC). Between 1993-2014 Phaeocystis spp. contributed ∼4.6% of the annual phytoplankton carbon and during the March - May spring bloom, the mean Phaeocystis spp. biomass constituted 17% with a maximal contribution of 47% in 2001. Upper maximal weekly values above the time series mean ranged from 63 to 82% of the total phytoplankton carbon (∼42-137mg carbon (C)m(-3)) with significant inter-annual variability in Phaeocystis spp...
July 2017: Harmful Algae
https://www.readbyqxmd.com/read/28751404/microbiomes-of-american-oysters-crassostrea-virginica-harvested-from-two-sites-in-the-chesapeake-bay
#7
Sylvia Ossai, Padmini Ramachandran, Andrea Ottesen, Elizabeth Reed, Angelo DePaola, Salina Parveen
In this study, we used 16S rRNA gene amplicons to describe the bacterial microbiota associated with oysters (Crassostrea virginica) and seawater collected from two sites in the Chesapeake Bay. The dominant bacterial groups included those belonging to the order Pelagibacteraceae, family Enterobacteriaceae, and genus Synechococcus The microbiomes varied among oysters from the same site and between the two sites and months.
July 27, 2017: Genome Announcements
https://www.readbyqxmd.com/read/28745633/determination-of-the-glycogen-content-in-cyanobacteria
#8
Alice De Porcellinis, Niels-Ulrik Frigaard, Yumiko Sakuragi
Cyanobacteria accumulate glycogen as a major intracellular carbon and energy storage during photosynthesis. Recent developments in research have highlighted complex mechanisms of glycogen metabolism, including the diel cycle of biosynthesis and catabolism, redox regulation, and the involvement of non-coding RNA. At the same time, efforts are being made to redirect carbon from glycogen to desirable products in genetically engineered cyanobacteria to enhance product yields. Several methods are used to determine the glycogen contents in cyanobacteria, with variable accuracies and technical complexities...
July 17, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28744260/pipy-a-member-of-the-conserved-cog0325-family-of-plp-binding-proteins-expands-the-cyanobacterial-nitrogen-regulatory-network
#9
José I Labella, Raquel Cantos, Javier Espinosa, Alicia Forcada-Nadal, Vicente Rubio, Asunción Contreras
Synechococcus elongatus PCC 7942 is a paradigmatic model organism for nitrogen regulation in cyanobacteria. Expression of genes involved in nitrogen assimilation is positively regulated by the 2-oxoglutarate receptor and global transcriptional regulator NtcA. Maximal activation requires the subsequent binding of the co-activator PipX. PII, a protein found in all three domains of life as an integrator of signals of the nitrogen and carbon balance, binds to PipX to counteract NtcA activity at low 2-oxoglutarate levels...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28737704/toxicity-at-the-edge-of-life-a-review-on-cyanobacterial-toxins-from-extreme-environments
#10
REVIEW
Samuel Cirés, María Cristina Casero, Antonio Quesada
Cyanotoxins are secondary metabolites produced by cyanobacteria, of varied chemical nature and toxic effects. Although cyanobacteria thrive in all kinds of ecosystems on Earth even under very harsh conditions, current knowledge on cyanotoxin distribution is almost restricted to freshwaters from temperate latitudes. In this review, we bring to the forefront the presence of cyanotoxins in extreme environments. Cyanotoxins have been reported especially in polar deserts (both from the Arctic and Antarctica) and alkaline lakes, but also in hot deserts, hypersaline environments, and hot springs...
July 24, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28732467/minimal-tool-set-for-a-prokaryotic-circadian-clock
#11
Nicolas M Schmelling, Robert Lehmann, Paushali Chaudhury, Christian Beck, Sonja-Verena Albers, Ilka M Axmann, Anika Wiegard
BACKGROUND: Circadian clocks are found in organisms of almost all domains including photosynthetic Cyanobacteria, whereby large diversity exists within the protein components involved. In the model cyanobacterium Synechococcus elongatus PCC 7942 circadian rhythms are driven by a unique KaiABC protein clock, which is embedded in a network of input and output factors. Homologous proteins to the KaiABC clock have been observed in Bacteria and Archaea, where evidence for circadian behavior in these domains is accumulating...
July 21, 2017: BMC Evolutionary Biology
https://www.readbyqxmd.com/read/28731528/improving-succinate-productivity-by-engineering-a-cyanobacterial-co2-concentrating-system-ccm-in-escherichia-coli
#12
Mengyong Xiao, Xinna Zhu, Changhao Bi, Yanhe Ma, Xueli Zhang
Biologically fixation of CO2 has great potential as a significant carbon source for biosynthesis, which is also a major way to reduce CO2 accumulation in atmosphere. Phosphoenolpyruvate (PEP) carboxylation is the key step of anaerobic succinate production in Escherichia coli. In this reaction, one mole CO2 is assimilated with PEP to form oxaloacetate by PEP carboxykinase (PCK). The preferred substrate of PCK is CO2 , which is very limited in cytoplasm. In this study, the carbon concentration mechanism (CCM) of cyanobacteria was introduced into E...
July 21, 2017: Biotechnology Journal
https://www.readbyqxmd.com/read/28731472/high-abundance-and-expression-of-transposases-in-bacteria-from-the-baltic-sea
#13
Theoden Vigil-Stenman, Karolina Ininbergs, Birgitta Bergman, Martin Ekman
Transposases are mobile genetic elements suggested to have an important role in bacterial genome plasticity and host adaptation but their transcriptional activity in natural bacterial communities is largely unexplored. Here we analyzed metagenomes and -transcriptomes of size fractionated (0.1-0.8, 0.8-3.0 and 3.0-200 μm) bacterial communities from the brackish Baltic Sea, and adjacent marine waters. The Baltic Sea transposase levels, up to 1.7% of bacterial genes and 2% of bacterial transcripts, were considerably higher than in marine waters and similar to levels reported for extreme environments...
July 21, 2017: ISME Journal
https://www.readbyqxmd.com/read/28729864/synechococcus-assemblages-across-the-salinity-gradient-in-a-salt-wedge-estuary
#14
Xiaomin Xia, Wang Guo, Shangjin Tan, Hongbin Liu
Synechococcus are the most abundant and widely distributed picocyanobacteria in the ocean. The salt-wedge type of estuary possesses the complete horizontal and vertical gradient of salinity together with other physical and chemical parameters. In order to reveal whether such a complex environmental gradient harbors a high diversity of Synechococcus, we investigated the abundance, taxonomic composition and pigment genetic diversity of Synechococcus in surface and bottom waters across the salinity gradient in a salt-wedge estuary by flow cytometric analysis and pyrosequencing of the rpoC1 gene and cpcBA operon (encoding phycocyanin)...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28729858/toxin-antitoxin-systems-in-estuarine-synechococcus-strain-cb0101-and-their-transcriptomic-responses-to-environmental-stressors
#15
David Marsan, Allen Place, Daniel Fucich, Feng Chen
Bacterial toxin-antitoxin (TA) systems are genetic elements composed of a toxin gene and its cognate antitoxin, with the ability to regulate growth. TA systems have not previously been reported in marine Synechococcus or Prochlorococcus. Here we report the finding of seven TA system pairs (Type II) in the estuarine Synechococcus CB0101, and their responses of these TA genes to under different stress conditions, which include; nitrogen and phosphate starvation, phage infection, zinc toxicity, and photo-oxidation...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28720699/cellular-trade-offs-and-optimal-resource-allocation-during-cyanobacterial-diurnal-growth
#16
Alexandra-M Reimers, Henning Knoop, Alexander Bockmayr, Ralf Steuer
Cyanobacteria are an integral part of Earth's biogeochemical cycles and a promising resource for the synthesis of renewable bioproducts from atmospheric CO2 Growth and metabolism of cyanobacteria are inherently tied to the diurnal rhythm of light availability. As yet, however, insight into the stoichiometric and energetic constraints of cyanobacterial diurnal growth is limited. Here, we develop a computational framework to investigate the optimal allocation of cellular resources during diurnal phototrophic growth using a genome-scale metabolic reconstruction of the cyanobacterium Synechococcus elongatus PCC 7942...
July 18, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28718632/systematic-approaches-to-efficiently-produce-2-3-butanediol-in-a-marine-cyanobacterium
#17
Nicole E Nozzi, Anna E Case, Austin L Carroll, Shota Atsumi
Cyanobacteria have attracted significant interest as a platform for renewable production of fuel and feedstock chemicals from abundant atmospheric carbon dioxide by way of photosynthesis. While great strides have been made in developing this technology in freshwater cyanobacteria, logistical issues remain in scale-up. Use of the cyanobacterium Synechococcus sp. PCC 7002 (7002) as a chemical production chassis could address a number of these issues given the higher tolerance to salt, light, and heat as well as the fast growth rate of 7002 in comparison to traditional model cyanobacteria such as Synechococcus elongatus PCC 7942 and Synechocystis sp...
July 18, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28680419/novel-synechococcus-genomes-reconstructed-from-freshwater-reservoirs
#18
Pedro J Cabello-Yeves, Jose M Haro-Moreno, Ana-Belen Martin-Cuadrado, Rohit Ghai, Antonio Picazo, Antonio Camacho, Francisco Rodriguez-Valera
Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb) and average intergenic spacer length (20 bp) of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28667427/variation-of-synechococcus-pigment-genetic-diversity-along-two-turbidity-gradients-in-the-china-seas
#19
Xiaomin Xia, Hongbin Liu, Donghan Choi, Jae Hoon Noh
Synechococcus are important and widely distributed picocyanobacteria that encompass a high pigment diversity. In this study, we developed a primer set (peBF/peAR) for amplifying the cpeBA operon sequence from Synechococcus genomic DNA to study Synechococcus pigment diversity along two turbidity gradients in the China seas. Our data revealed that all previously reported pigment types occurred in the South (SCS) and East (ECS) China Seas. In addition, a novel pigment genetic type (type 3f), represented by the high phycourobilin Synechococcus sp...
July 1, 2017: Microbial Ecology
https://www.readbyqxmd.com/read/28667417/enhanced-biomass-and-oxidative-stress-tolerance-of-synechococcus-elongatus-pcc-7942-overexpressing-the-dhar-gene-from-brassica-juncea
#20
Young-Saeng Kim, Il-Sup Kim, Joseph S Boyd, Arnaud Taton, James W Golden, Ho-Sung Yoon
OBJECTIVES: To improve the oxidative stress tolerance, biomass yield, and ascorbate/dehydroascorbate (AsA/DHA) ratio of Synechococcus elongatus PCC 7942 in the presence of H2O2, by heterologous expression of the dehydroascorbate reductase (DHAR) gene from Brassica juncea (BrDHAR). RESULTS: Under H2O2 stress, overexpression of BrDHAR in the transgenic strain (BrD) of S. elongatus greatly increased the AsA/DHA ratio. As part of the AsA recycling system, the oxidative stress response induced by reactive oxygen species was enhanced, and intracellular H2O2 level decreased...
June 30, 2017: Biotechnology Letters
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