Search results for "CYANOBACTERIA"
showing 10 items of 130 documents
Alternative Rieske Iron-Sulfur Subunits and Small Polypeptides of Cyanobacterial Cytochrome b 6 f Complexes
2016
The cytochrome (cyt) b6f complex is a central component of both, photosynthetic and respiratory electron- and proton transport processes in cyanobacteria. Among its eight bona fide subunits, the Rieske [2Fe-2S] protein is encoded by multiple genes in most cyanobacterial genomes. However, the significance of the resulting protein heterogeneity is essentially not yet understood. The following chapter provides an overview on the Rieske [2Fe-2S] protein diversity in cyanobacteria, and related aspects. In addition, potential roles of small cyt b6f complex subunits are discussed.
Experimental modeling of bacterially-induced Ca carbonate precipitation: new insights on possible mechanisms.
2015
The contribution of microorganisms, particularly bacteria, in carbonate mineral formation, the main natural processes controlling CO2 level in the atmosphere, has played an important role since the Archean Eon. In this study we review our recent experimental work on CaCO3 precipitation induced by two anoxygenic phototrophic bacteria (APB), Rhodovulum steppense A-20sT and Rhodovulum sp. S-17-65, and by cyanobacteria Gloeocapsa sp. f-6gl. These bacteria are representatives of two important groups of photosynthetic organisms present at the Earth surface both in the past and at the present times. The mechanisms of organomineralization deriving from APB and cyanobacteria activities are drastical…
The Supramolecular Structure of Photosystem II — Phycobilisome‐Complexes of Porphyridium cruentum
1990
The structure and arrangement of phycobilisomes of the unicellular red alga Porphyridium cruentum is compared with the organization of the thylakoid freeze-fracture particles in order to determine the relationship between phycobilisomes and photosystem II. The hemi-ellipsoidal phycobilisomes, 20 nm thick, are predominantly organized into rows; their centre to centre periodicity is 30–40 nm, so that they are well separated by a gap of 10–20 nm. The phycobilisomes are cleaved by a central faint furrow, parallel to the long axis from top to base. The organization of the exoplasmic particles in rows is similar to the arrangement of the phycobilisomes so that a structural relationship between bo…
Inferring phytoplankton community composition with a fatty acid mixing model
2015
The taxon specificity of fatty acid composition in algal classes suggests that fatty acids could be used as chemotaxonomic markers for phytoplankton composition. The applicability of phospholipid-derived fatty acids as chemotaxonomic markers for phytoplankton composition was evaluated by using a Bayesian fatty acid-based mixing model. Fatty acid profiles from monocultures of chlorophytes, cyanobacteria, diatoms, euglenoids, dinoflagellates, raphidophyte, cryptophytes and chrysophytes were used as a reference library to infer phytoplankton community composition in five moderately humic, large boreal lakes in three different seasons (spring, summer and fall). The phytoplankton community compo…
The Biosynthesis of Rare Homo-Amino Acid Containing Variants of Microcystin by a Benthic Cyanobacterium
2019
Microcystins are a family of chemically diverse hepatotoxins produced by distantly related cyanobacteria and are potent inhibitors of eukaryotic protein phosphatases 1 and 2A. Here we provide evidence for the biosynthesis of rare variants of microcystin that contain a selection of homo-amino acids by the benthic cyanobacterium Phormidium sp. LP904c. This strain produces at least 16 microcystin chemical variants many of which contain homophenylalanine or homotyrosine. We retrieved the complete 54.2 kb microcystin (mcy) gene cluster from a draft genome assembly. Analysis of the substrate specificity of McyB1 and McyC adenylation domain binding pockets revealed divergent substrate specificity …
A single primer pair gives a specific ortholog amplicon in a wide range of Cyanobacteria and plastid-bearing organisms: applicability in inventory of…
2010
The scarcity of universally applied molecular markers for algae has resulted in the development of multiple, independent and not easily comparable systems. The goal of this work is to increase the number of available molecular markers and to generate easily comparable systems. Thereby, we have designed a primer pair capable of amplifying a broad range of organisms: Cyanobacteria, Chlorophyta, Chlorarachniophyta, Cryptophyta, Euglenida, Glaucophyta, Rhodophyta, Stramenopiles and Streptophyta including plants. This primer pair can amplify a portion of the 23S rRNA gene with sufficient variability to identify reference material form collections across a broad range of taxa and perform phylogen…
Key roles for freshwater A ctinobacteria revealed by deep metagenomic sequencing
2014
Freshwater ecosystems are critical but fragile environments directly affecting society and its welfare. However, our understanding of genuinely freshwater microbial communities, constrained by our capacity to manipulate its prokaryotic participants in axenic cultures, remains very rudimentary. Even the most abundant components, freshwater Actinobacteria, remain largely unknown. Here, applying deep metagenomic sequencing to the microbial community of a freshwater reservoir, we were able to circumvent this traditional bottleneck and reconstruct de novo seven distinct streamlined actinobacterial genomes. These genomes represent three new groups of photoheterotrophic, planktonic Actinobacteria.…
A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins
2018
Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The Europea…
Phytoplankton communities of polar regions–Diversity depending on environmental conditions and chemical anthropopressure
2015
The polar regions (Arctic and Antarctic) constitute up to 14% of the biosphere and offer some of the coldest and most arid Earth's environments. Nevertheless several oxygenic phototrophs including some higher plants, mosses, lichens, various algal groups and cyanobacteria, survive that harsh climate and create the base of the trophic relationships in fragile ecosystems of polar environments. Ecosystems in polar regions are characterized by low primary productivity and slow growth rates, therefore they are more vulnerable to disturbance, than those in temperate regions. From this reason, chemical contaminants influencing the growth of photoautotrophic producers might induce serious disorders…
Plankton participation in the performance of three constructed wetlands within a Mediterranean natural park.
2019
Abstract The contribution of plankton in the performance of three constructed wetlands (CWs) within the Albufera de Valencia Natural Park has been analyzed, taxonomic group by group, over a two-year operation period in the different sectors of each CW: horizontal subsurface-flow –A–, free-water surface flow –B– and lagoons –C–. Tancat de la Pipa CW (TPCW) only contains B–C sectors, while the others have all three types. Treatment efficiency of each sector type on the taxonomic groups was evaluated by calculating frequency of phytoplankton reduction (or zooplankton production), mass removal (or production) efficiencies and rates, and accumulated removed phytoplankton mass (or produced zoopla…