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1.
Photosynth Res ; 141(3): 259-271, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30903482

RESUMO

The cyanobacterial culture HT-58-2, composed of a filamentous cyanobacterium and accompanying community bacteria, produces chlorophyll a as well as the tetrapyrrole macrocycles known as tolyporphins. Almost all known tolyporphins (A-M except K) contain a dioxobacteriochlorin chromophore and exhibit an absorption spectrum somewhat similar to that of chlorophyll a. Here, hyperspectral confocal fluorescence microscopy was employed to noninvasively probe the locale of tolyporphins within live cells under various growth conditions (media, illumination, culture age). Cultures grown in nitrate-depleted media (BG-110 vs. nitrate-rich, BG-11) are known to increase the production of tolyporphins by orders of magnitude (rivaling that of chlorophyll a) over a period of 30-45 days. Multivariate curve resolution (MCR) was applied to an image set containing images from each condition to obtain pure component spectra of the endogenous pigments. The relative abundances of these components were then calculated for individual pixels in each image in the entire set, and 3D-volume renderings were obtained. At 30 days in media with or without nitrate, the chlorophyll a and phycobilisomes (combined phycocyanin and phycobilin components) co-localize in the filament outer cytoplasmic region. Tolyporphins localize in a distinct peripheral pattern in cells grown in BG-110 versus a diffuse pattern (mimicking the chlorophyll a localization) upon growth in BG-11. In BG-110, distinct puncta of tolyporphins were commonly found at the septa between cells and at the end of filaments. This work quantifies the relative abundance and envelope localization of tolyporphins in single cells, and illustrates the ability to identify novel tetrapyrroles in the presence of chlorophyll a in a photosynthetic microorganism within a non-axenic culture.


Assuntos
Cianobactérias/metabolismo , Fotossíntese , Porfirinas/metabolismo , Tetrapirróis/metabolismo , Adaptação Fisiológica , Bacterioclorofila A/química , Clorofila A/química , Cianobactérias/ultraestrutura , Escuridão , Microscopia Confocal , Microscopia de Fluorescência , Porfirinas/química , Tetrapirróis/química
2.
J Vis Exp ; (143)2019 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-30663718

RESUMO

Scanning electron microscopy (SEM) is a widely available technique that has been applied to study biological specimens ranging from individual proteins to cells, tissues, organelles, and even whole organisms. This protocol focuses on two chemical drying methods, hexamethyldisilazane (HMDS) and t-butyl alcohol (TBA), and their application to imaging of both prokaryotic and eukaryotic organisms using SEM. In this article, we describe how to fix, wash, dehydrate, dry, mount, sputter coat, and image three types of organisms: cyanobacteria (Toxifilum mysidocida, Golenkina sp., and an unknown sp.), two euglenoids from the genus Monomorphina (M. aenigmatica and M. pseudopyrum), and the fruit fly (Drosophila melanogaster). The purpose of this protocol is to describe a fast, inexpensive, and simple method to obtain detailed information about the structure, size, and surface characteristics of specimens that can be broadly applied to a large range of organisms for morphological assessment. Successful completion of this protocol will allow others to use SEM to visualize samples by applying these techniques to their system.


Assuntos
Dessecação/métodos , Células Eucarióticas/ultraestrutura , Microscopia Eletrônica de Varredura , Células Procarióticas/ultraestrutura , Animais , Cianobactérias/ultraestrutura , Drosophila melanogaster/ultraestrutura , Euglena/ultraestrutura , Células Eucarióticas/metabolismo , Olho/ultraestrutura , Compostos de Organossilício , Fenótipo , Células Procarióticas/metabolismo
3.
Genome Biol Evol ; 11(1): 270-294, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30590650

RESUMO

Cyanobacteria are dominant primary producers of various ecosystems and they colonize marine as well as freshwater and terrestrial habitats. On the basis of their oxygenic photosynthesis they are known to synthesize a high number of secondary metabolites, which makes them promising for biotechnological applications. State-of-the-art sequencing and analytical techniques and the availability of several axenic strains offer new opportunities for the understanding of the hidden metabolic potential of cyanobacteria beyond those of single model organisms. Here, we report comprehensive genomic and metabolic analyses of five non-marine cyanobacteria, that is, Nostoc sp. DSM 107007, Anabaena variabilis DSM 107003, Calothrix desertica DSM 106972, Chroococcidiopsis cubana DSM 107010, Chlorogloeopsis sp. PCC 6912, and the reference strain Synechocystis sp. PCC 6803. Five strains that are prevalently belonging to the order Nostocales represent the phylogenetic depth of clade B1, a morphologically highly diverse sister lineage of clade B2 that includes strain PCC 6803. Genome sequencing, light and scanning electron microscopy revealed the characteristics and axenicity of the analyzed strains. Phylogenetic comparisons showed the limits of the 16S rRNA gene for the classification of cyanobacteria, but documented the applicability of a multilocus sequence alignment analysis based on 43 conserved protein markers. The analysis of metabolites of the core carbon metabolism showed parts of highly conserved metabolic pathways as well as lineage specific pathways such as the glyoxylate shunt, which was acquired by cyanobacteria at least twice via horizontal gene transfer. Major metabolic changes were observed when we compared alterations between day and night samples. Furthermore, our results showed metabolic potential of cyanobacteria beyond Synechocystis sp. PCC 6803 as model organism and may encourage the cyanobacterial community to broaden their research to related organisms with higher metabolic activity in the desired pathways.


Assuntos
Ritmo Circadiano , Cianobactérias/metabolismo , Filogenia , Cianobactérias/genética , Cianobactérias/ultraestrutura , Genoma Bacteriano
4.
Elife ; 72018 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-30520729

RESUMO

Carboxysomes are protein-based bacterial organelles encapsulating key enzymes of the Calvin-Benson-Bassham cycle. Previous work has implicated a ParA-like protein (hereafter McdA) as important for spatially organizing carboxysomes along the longitudinal axis of the model cyanobacterium Synechococcus elongatus PCC 7942. Yet, how self-organization of McdA emerges and contributes to carboxysome positioning is unknown. Here, we identify a small protein, termed McdB that localizes to carboxysomes and drives emergent oscillatory patterning of McdA on the nucleoid. Our results demonstrate that McdB directly stimulates McdA ATPase activity and its release from DNA, driving carboxysome-dependent depletion of McdA locally on the nucleoid and promoting directed motion of carboxysomes towards increased concentrations of McdA. We propose that McdA and McdB are a previously unknown class of self-organizing proteins that utilize a Brownian-ratchet mechanism to position carboxysomes in cyanobacteria, rather than a cytoskeletal system. These results have broader implications for understanding spatial organization of protein mega-complexes and organelles in bacteria.


Assuntos
Proteínas de Bactérias/metabolismo , Carbono/metabolismo , Cianobactérias/metabolismo , Grânulos Citoplasmáticos/metabolismo , DNA Bacteriano/metabolismo , Proteínas de Bactérias/genética , Ciclo do Carbono , Dióxido de Carbono/metabolismo , Cianobactérias/genética , Cianobactérias/ultraestrutura , Grânulos Citoplasmáticos/ultraestrutura , DNA Bacteriano/genética , Genoma Bacteriano/genética , Microscopia Eletrônica de Transmissão , Modelos Biológicos , Movimento , Fotossíntese , Ligação Proteica , Synechococcus/genética , Synechococcus/metabolismo , Synechococcus/ultraestrutura
5.
J Mol Biol ; 430(21): 4156-4167, 2018 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-30138616

RESUMO

Cyanobacteria are photosynthetic organisms responsible for ~25% of the organic carbon fixation on earth. A key step in carbon fixation is catalyzed by ribulose bisphosphate carboxylase/oxygenase (RuBisCO), the most abundant enzyme in the biosphere. Applying Zernike phase-contrast electron cryo-tomography and automated annotation, we identified individual RuBisCO molecules and their assembly intermediates leading to the formation of carboxysomes inside Syn5 cyanophage infected cyanobacteria Synechococcus sp. WH8109 cells. Surprisingly, more RuBisCO molecules were found to be present as cytosolic free-standing complexes or clusters than as packaged assemblies inside carboxysomes. Cytosolic RuBisCO clusters and partially assembled carboxysomes identified in the cell tomograms support a concurrent assembly model involving both the protein shell and the enclosed RuBisCO. In mature carboxysomes, RuBisCO is neither randomly nor strictly icosahedrally packed within protein shells of variable sizes. A time-averaged molecular dynamics simulation showed a semi-liquid probability distribution of the RuBisCO in carboxysomes and correlated well with carboxysome subtomogram averages. Our structural observations reveal the various stages of RuBisCO assemblies, which could be important for understanding cellular function.


Assuntos
Organismos Aquáticos/metabolismo , Organismos Aquáticos/ultraestrutura , Microscopia Crioeletrônica , Cianobactérias/metabolismo , Cianobactérias/ultraestrutura , Ribulose-Bifosfato Carboxilase/química , Ribulose-Bifosfato Carboxilase/ultraestrutura , Animais , Camundongos , Conformação Molecular , Simulação de Dinâmica Molecular
6.
J Phycol ; 54(5): 638-652, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30055049

RESUMO

Two untapered, heterocytous species were observed and collected from the intertidal and supratidal zones of the Mexican coastline of the Pacific Ocean near Oaxaca and from the Gulf of Mexico. These populations were highly similar in morphology to the freshwater taxon Petalonema incrustans in the Scytonemataceae. However, 16S rRNA sequence data and phylogenetic analysis indicated that they were sister taxa to the epiphyllic, Brazilian species Phyllonema aveceniicola in the Rivulariaceae, described from culture material. While genetic identity between the two new species was high, they differed significantly in morphology, 16S rRNA gene sequence identity, and sequence and structure of the 16S-23S ITS region. Their morphology differed markedly from the generitype of the previously monotypic Phyllonema, which has tapered, heteropolar, single-false branched trichomes with very thin or absent sheath. The two new species, Phyllonema ansata and Phyllonema tangolundensis, described from both culture and environmental material, have untapered, isopolar, geminately false branched trichomes with thick, lamellated sheaths, differences so significant that the species would not be placed in Phyllonema without molecular corroboration. The morphological differences are so significant that a formal emendation of the genus is required. These taxa provide a challenge to algal taxonomy because the morphological differences are such that one would logically conclude that they represent different genera, but the phylogenetic evidence for including them all in the same genus is conclusive. This conclusion is counter to the current trend in algal taxonomy in which taxa with minor morphological differences have been repeatedly placed in separate genera based primarily upon DNA sequence evidence.


Assuntos
Cianobactérias/classificação , Cianobactérias/citologia , Proteínas de Algas/análise , Cianobactérias/genética , Cianobactérias/ultraestrutura , DNA Espaçador Ribossômico/análise , México , Filogenia , Estrutura Secundária de Proteína , RNA de Algas/análise , RNA Ribossômico 16S/análise , Análise de Sequência de RNA
7.
Nat Commun ; 9(1): 2168, 2018 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-29867170

RESUMO

Oxygenic photosynthetic organisms perform solar energy conversion of water and CO2 to O2 and sugar at a broad range of wavelengths and light intensities. These cells also metabolize sugars using a respiratory system that functionally overlaps the photosynthetic apparatus. In this study, we describe the harvesting of photocurrent used for hydrogen production from live cyanobacteria. A non-harmful gentle physical treatment of the cyanobacterial cells enables light-driven electron transfer by an endogenous mediator to a graphite electrode in a bio-photoelectrochemical cell, without the addition of sacrificial electron donors or acceptors. We show that the photocurrent is derived from photosystem I and that the electrons originate from carbohydrates digested by the respiratory system. Finally, the current is utilized for hydrogen evolution on the cathode at a bias of 0.65 V. Taken together, we present a bio-photoelectrochemical system where live cyanobacteria produce stable photocurrent that can generate hydrogen.


Assuntos
Cianobactérias/metabolismo , Hidrogênio/metabolismo , Luz , Consumo de Oxigênio/efeitos da radiação , Fotossíntese/efeitos da radiação , Proteínas de Bactérias/metabolismo , Cianobactérias/ultraestrutura , Transporte de Elétrons/efeitos da radiação , Microscopia Eletrônica de Varredura , Complexo de Proteína do Fotossistema I/metabolismo , Synechocystis/metabolismo , Synechocystis/ultraestrutura
8.
Geobiology ; 16(5): 476-497, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29923673

RESUMO

The 2.1-billion-year-old (Ga) Francevillian series in Gabon hosts some of the oldest reported macroscopic fossils of various sizes and shapes, stimulating new debates on the origin, evolution and organization of early complex life. Here, we document ten representative types of exceptionally well-preserved mat-related structures, comprising "elephant-skin" textures, putative macro-tufted microbial mats, domal buildups, flat pyritized structures, discoidal microbial colonies, horizontal mat growth patterns, wrinkle structures, "kinneyia" structures, linear patterns and nodule-like structures. A combination of petrographic analyses, scanning electron microscopy, Raman spectroscopy and organic elemental analyses of carbon-rich laminae and microtexture, indicate a biological origin for these structures. The observed microtextures encompass oriented grains, floating silt-sized quartz grains, concentrated heavy minerals, randomly oriented clays, wavy-crinkly laminae and pyritized structures. Based on comparisons with modern analogues, as well as an average δ13 C organic matter (Corg ) composition of -32.94 ± 1.17‰ (1 standard deviation, SD) with an outlier of -41.26‰, we argue that the mat-related structures contain relicts of multiple carbon pathways including heterotrophic recycling of photosynthetically derived Corg . Moreover, the relatively close association of the macroscopic fossil assemblages to the microbial mats may imply that microbial communities acted as potential benthic O2 oases linked to oxyphototrophic cyanobacterial mats and grazing grounds. In addition, the mat's presence likely improved the preservation of the oldest large colonial organisms, as they are known to strongly biostabilize sediments. Our findings highlight the oldest community assemblage of microscopic and macroscopic biota in the aftermath of the "Great Oxidation Event," widening our understanding of biological organization during Earth's middle age.


Assuntos
Fósseis/microbiologia , Biota/fisiologia , Cianobactérias/metabolismo , Cianobactérias/ultraestrutura , Sedimentos Geológicos/microbiologia , Microscopia Eletrônica de Varredura , Compostos Orgânicos/metabolismo , Análise Espectral Raman
9.
Mol Phylogenet Evol ; 120: 196-211, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29246815

RESUMO

Brazil has an extensive and environmentally diverse coastline, which favors the occurrence of numerous cyanobacterial morpho- and ecotypes. Nevertheless, this coastline is still poorly studied and its diversity is underestimated. Considering the family Oscillatoriaceae, Lyngbya deserves special attention. It includes many clades which are phylogenetically non-related but morphologically similar. Such clades occur in marine and freshwater environments and are traditionally treated as a single genus. In the current study, we sampled both mediolittoral and estuarine zones along the Brazilian coast. Based on a polyphasic characterization, we described a new genus of marine filamentous cyanobacteria: Neolyngbya. It includes six new species sampled in Brazil, which are described in this study (N. maris-brasilis, N. granulosa, N. irregularis, N. nodulosa, N. arenicola and N. tenuis). Additionally, the characterization included a Neolyngbya sp. from Japan in the clade, but only based on molecular data. All species presented irregular arrangement of thylakoids as described for Oscillatoriaceae. The new genus shares morphological characteristics with species in different clades of the Lyngbya complex. The ultrastructural analyses of Neolyngbya, however, showed numerous gas vesicles, especially in the interthylakoid space; such feature is not observed in benthic Lyngbya species. Neolyngbya formed a well-supported clade (16S rRNA phylogeny), however distantly related to L. aestuarii and L. confervoides, both marine species clusters. The Limnoraphis clade is in a sister relationship to the Neolyngbya clade, however the former occurs in freshwater plankton. Secondary structures of 16S-23S rRNA ITS sequences were congruent with the phylogeny. The polyphasic characterization was helpful to clarify the diversity and ecological aspects of benthic filamentous cyanobacteria and the evolutionary history of the group. This favors a better understanding of inter and infrageneric taxa. The number of novel taxa described in this study emphasizes the importance of conducting additional floristic surveys, mainly in underexplored marine environments, to reveal the real cyanobacterial biodiversity in these areas.


Assuntos
Cianobactérias/classificação , Biodiversidade , Brasil , Cianobactérias/genética , Cianobactérias/ultraestrutura , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Microscopia Eletrônica de Transmissão , Filogenia , RNA Ribossômico 16S/química , RNA Ribossômico 16S/classificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
10.
Photosynth Res ; 135(1-3): 165-175, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28378245

RESUMO

The bioavailable iron in many aquatic ecosystems is extremely low, and limits the growth and photosynthetic activity of phytoplankton. In response to iron limitation, a group of chlorophyll-binding proteins known as iron stress-induced proteins are induced and serve as accessory light-harvesting components for photosystems under iron limitation. In the present study, we investigated physiological features of Acaryochloris marina in response to iron-deficient conditions. The growth doubling time under iron-deficient conditions was prolonged to ~3.4 days compared with 1.9 days under normal culture conditions, accompanied with dramatically decreased chlorophyll content. The isolation of chlorophyll-binding protein complexes using sucrose density gradient centrifugation shows six main green bands and three main fluorescence components of 712, 728, and 748 nm from the iron-deficient culture. The fluorescence components of 712 and 728 nm co-exist in the samples collected from iron-deficient and iron-replete cultures and are attributed to Chl d-binding accessory chlorophyll-binding antenna proteins and also from photosystem II. A new chlorophyll-binding protein complex with its main fluorescence peak at 748 nm was observed and enriched in the heaviest fraction from the samples collected from the iron-deficient culture only. Combining western blotting analysis using antibodies of CP47 (PSII), PsaC (PSI) and IsiA and proteomic analysis on an excised protein band at ~37 kDa, the heaviest fraction (-F6) isolated from iron-deficient culture contained Chl d-bound PSI-IsiA supercomplexes. The PSII-antenna supercomplexes isolated from iron-replete conditions showed two fluorescence peaks of 712 and 728 nm, which can be assigned as 6-transmembrane helix chlorophyll-binding antenna and photosystem II fluorescence, respectively, which is supported by protein analysis of the fractions (F5 and F6).


Assuntos
Proteínas de Bactérias/metabolismo , Clorofila/metabolismo , Cianobactérias/metabolismo , Proteínas de Ligação à Clorofila/metabolismo , Cianobactérias/efeitos dos fármacos , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/ultraestrutura , Ferro/farmacologia , Complexos Multiproteicos/metabolismo , Ligação Proteica/efeitos dos fármacos , Espectrometria de Fluorescência , Temperatura Ambiente , Tilacoides/efeitos dos fármacos , Tilacoides/metabolismo , Tilacoides/efeitos da radiação
11.
Photosynth Res ; 134(2): 183-192, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28895022

RESUMO

Far-Red Light (FRL) acclimation is a process that has been observed in cyanobacteria and algae that can grow solely on light above 700 nm. The acclimation to FRL results in rearrangement and synthesis of new pigments and pigment-protein complexes. In this study, cyanobacteria containing chlorophyll f, Synechococcus sp. PCC 7335 and Halomicronema hongdechloris, were imaged as live cells with confocal microscopy. H. hongdechloris was further studied with hyperspectral confocal fluorescence microscopy (HCFM) and freeze-substituted thin-section transmission electron microscopy (TEM). Under FRL, phycocyanin-containing complexes and chlorophyll-containing complexes were determined to be physically separated and the synthesis of red-form phycobilisome and Chl f was increased. The timing of these responses was observed. The heterogeneity and eco-physiological response of the cells was noted. Additionally, a gliding motility for H. hongdechloris is reported.


Assuntos
Aclimatação/efeitos da radiação , Clorofila/análogos & derivados , Cianobactérias/fisiologia , Luz , Ficobilissomas/metabolismo , Aclimatação/fisiologia , Clorofila/metabolismo , Cianobactérias/efeitos da radiação , Cianobactérias/ultraestrutura , Microscopia Eletrônica de Transmissão , Fotossíntese/fisiologia
12.
Nat Methods ; 14(10): 983-985, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28846087

RESUMO

Cellular electron cryotomography offers researchers the ability to observe macromolecules frozen in action in situ, but a primary challenge with this technique is identifying molecular components within the crowded cellular environment. We introduce a method that uses neural networks to dramatically reduce the time and human effort required for subcellular annotation and feature extraction. Subsequent subtomogram classification and averaging yield in situ structures of molecular components of interest. The method is available in the EMAN2.2 software package.


Assuntos
Criopreservação , Cianobactérias/ultraestrutura , Tomografia com Microscopia Eletrônica/métodos , Processamento de Imagem Assistida por Computador/métodos , Software
13.
Harmful Algae ; 67: 1-12, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28755712

RESUMO

In the last decades, the cyanobacterium Dolichospermum lemmermannii showed an increasing spread to Southern Europe, raising serious concerns due to its ability to produce cyanotoxins. The widening of its geographic distribution and the observation of strains showing high optimum temperature underline its ecological heterogeneity, suggesting the existence of different ecotypes. To investigate its biogeography, new isolates from different European water bodies, together with strains maintained by the Norwegian Institute for Water Research Culture Collection of Algae, were genetically characterised for the 16S rRNA gene and compared with strains obtained from public repositories. Geographic distance highly influenced the differentiation of genotypes, further suggesting the concurrent role of geographic isolation, physical barriers and environmental factors in promoting the establishment of phylogenetic lineages adapted to specific habitats. Differences among populations were also examined by morphological analysis and evaluating the toxic potential of single strains, which revealed the exclusive ability of North European strains to produce microcystins, whereas the populations in Southern Europe tested negative for a wide range of cyanotoxins. The high dispersion ability and the existence of toxic genotypes indicate the possible spread of harmful blooms in other temperate regions.


Assuntos
Cianobactérias/classificação , Proliferação Nociva de Algas , Microcistinas/biossíntese , Filogeografia , Cianobactérias/isolamento & purificação , Cianobactérias/ultraestrutura , Funções Verossimilhança , Filogenia , Análise de Componente Principal , RNA Ribossômico 16S/genética
14.
Biochim Biophys Acta Bioenerg ; 1858(9): 742-749, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28576442

RESUMO

Heterocyst is a nitrogen-fixing cell differentiated from a cell for oxygen-evolving photosynthesis (vegetative cell) in some filamentous cyanobacteria when fixed nitrogen (e.g., ammonia and nitrate) is limited. Heterocysts appear at multiple separated positions in a single filament with an interval of 10-20 cells in some genera (including Anabaena variabilis). In other genera, a single heterocyst appears only at the basal terminal in a filament (including Rivularia M-261). Such morphological diversity may necessitate different properties of heterocysts. However, possible differences in heterocysts have largely remained unexplored due to the minority of heterocysts among major vegetative cells. Here, we have applied spectroscopic microscopy to Rivularia and A. variabilis to analyze their thylakoid membranes in individual cells. Absorption and fluorescence spectral imaging enabled us to estimate concentrations and interconnections of key photosynthetic components like photosystem I (PSI), photosystem II (PSII) and subunits of light-harvesting phycobilisome including phycocyanin (PC). The concentration of PC in heterocysts of Rivularia is far higher than that of A. variabilis. Fluorescence quantum yield of PC in Rivularia heterocysts was found to be virtually the same as those in its vegetative cells, while fluorescence quantum yield of PC in A. variabilis heterocysts was enhanced in comparison with its vegetative cells. PSI concentration in the thylakoid membranes of heterocysts seems to remain nearly the same as those of the vegetative cells in both the species. The average stoichiometric ratio between PSI monomer and PC hexamer in Rivularia heterocysts is estimated to be about 1:1.


Assuntos
Cianobactérias/ultraestrutura , Microscopia/métodos , Tilacoides/ultraestrutura , Absorção de Radiação , Anabaena variabilis/metabolismo , Anabaena variabilis/efeitos da radiação , Anabaena variabilis/ultraestrutura , Cianobactérias/metabolismo , Cianobactérias/efeitos da radiação , Membranas Intracelulares/ultraestrutura , Luz , Microscopia de Fluorescência , Fixação de Nitrogênio , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema I/efeitos da radiação , Ficobilissomas/efeitos da radiação , Ficobilissomas/ultraestrutura , Ficocianina/análise , Especificidade da Espécie , Análise Espectral/métodos , Tilacoides/metabolismo , Tilacoides/efeitos da radiação
15.
Environ Manage ; 60(2): 293-303, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28477239

RESUMO

Freshwater cyanobacterium Pseudanabaena galeata were cultured in chambers under artificially generated pressures, which correspond to the hydrostatic pressures at deep water. Variations occurred in gas vesicles volume, and buoyancy state of cells under those conditions were analyzed at different time intervals (5 min, 1 day, and 5 days). Variations in gas vesicles morphology of cells were observed by transmission electron microscopy images. Settling velocity (Vs) of cells which governs the buoyancy was observed with the aid of a modified optical microscope. Moreover, effects of the prolonged pressure on cell ballast composition (protein and polysaccharides) were examined. Elevated pressure conditions reduced the cell ballast and caused a complete disappearance of gas vesicles in Pseudanabaena galeata cells. Hence cyanobacteria cells were not able to float within the study period. Observations and findings of the study indicate the potential application of hydrostatic pressure, which naturally occurred in hypolimnion of lakes, to inhibit the re-suspension of cyanobacteria cells.


Assuntos
Cianobactérias , Lagos/microbiologia , Pressão , Vacúolos , Fenômenos Fisiológicos Bacterianos , Cianobactérias/fisiologia , Cianobactérias/ultraestrutura , Microscopia Eletrônica de Transmissão , Modelos Teóricos , Temperatura Ambiente , Vacúolos/fisiologia , Vacúolos/ultraestrutura , Microbiologia da Água/normas , Movimentos da Água
16.
Environ Toxicol Pharmacol ; 51: 142-155, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28343753

RESUMO

In this study, we isolated five indigenous cyanobacterial strains from different aqueous environments, with heavy metals contamination, in East Azerbaijan Province (northwest portion of Iran). A strain was identified by morphological and 16S rRNA sequence analysis as Limnothrix sp. KO05 and selected for further studies as having the greatest potential for cadmium uptake. Scanning electron microscopy (SEM) demonstrated cyanobacterium Limnothrix sp. KO05 forms filamentous structures and is straight or curved to some extent. The utmost biosorption capacity was found to be 82.18±1.22mgg-1 at a Cd (II) concentration level of 150mgL-1. Langmuir adsorption isotherm indicated a better fit to the experimental data. Response surface methodology (RSM) on the basis of four independent variables and the predicted maximum biosorption efficiency was 98.7% under the optimum condition. FT-IR spectroscopy profile of the Cd treated sample as demonstrated in confirmation of the benefits of various functional groups of proteins and polysaccharides of cyanobacterial biomass, involved in surface binding of Cd. The determination of catalase (CAT) activity in strain KO05 exposed to Cd (II) concentrations of 2, 5 and 10mgL-1 showed an increase in enzyme activity after 24h exposure compared to unexposed cells. Correspondingly, CAT activity showed a significant decrease after 48h of treatment with Cd (II) concentrations of 5 and 10mgL-1. CAT activity was decreased significantly at all concentrations within 72h after exposure to Cd. On the contrary, while ascorbate peroxidase (APX) gave the expected lower activity compared to the CAT within 24h after Cd treatment, its activity lasted up to 72h. Limnothrix sp. KO05 cells treated with 5 and 10mgL-1 Cd (II) over 72h exposure showed a reduction in chlorophyll a contents compared to the controls. However, following exposure to Cd, chlorophyll a and carotenoid contents is reduced and after overcoming stress and deployment of an adaptation mechanism, the amounts of these pigments is gradually increased in the cells. The reduction was slower for chlorophyll a pigment compared to carotenoids that may be an indication of the physiological importance of chlorophyll pigment for the phtosynthetic cells. Results related to lipid peroxidation in Limnothrix sp. KO05 represent a significant increase of MDA in the first 24h after exposure to the different concentrations of Cd (2, 5 and 10mgL-1). However, the MDA levels were decreased over time and no significant difference attained after 72h exposure to Cd concentrations of 2 and 10mgL-1 compared to control.


Assuntos
Antioxidantes/metabolismo , Cádmio/toxicidade , Cianobactérias/efeitos dos fármacos , Cianobactérias/enzimologia , Modelos Teóricos , Poluentes Químicos da Água/toxicidade , Biodegradação Ambiental , Transporte Biológico , Biomassa , Cádmio/metabolismo , Cianobactérias/metabolismo , Cianobactérias/ultraestrutura , Monitoramento Ambiental , Irã (Geográfico) , Poluentes Químicos da Água/metabolismo
17.
Mol Phylogenet Evol ; 111: 18-34, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28279808

RESUMO

Aiming at increasing the knowledge on marine cyanobacteria from temperate regions, we previously isolated and characterized 60 strains from the Portuguese foreshore and evaluate their potential to produce secondary metabolites. About 15% of the obtained 16S rRNA gene sequences showed less than 97% similarity to sequences in the databases revealing novel biodiversity. Herein, seven of these strains were extensively characterized and their classification was re-evaluated. The present study led to the proposal of five new taxa, three genera (Geminobacterium, Lusitaniella, and Calenema) and two species (Hyella patelloides and Jaaginema litorale). Geminobacterium atlanticum LEGE 07459 is a chroococcalean that shares morphological characteristics with other unicellular cyanobacterial genera but has a distinct phylogenetic position and particular ultrastructural features. The description of the Pleurocapsales Hyella patelloides LEGE 07179 includes novel molecular data for members of this genus. The filamentous isolates of Lusitaniella coriacea - LEGE 07167, 07157 and 06111 - constitute a very distinct lineage, and seem to be ubiquitous on the Portuguese coast. Jaaginema litorale LEGE 07176 has distinct characteristics compared to their marine counterparts, and our analysis indicates that this genus is polyphyletic. The Synechococcales Calenema singularis possess wider trichomes than Leptolyngbya, and its phylogenetic position reinforces the establishment of this new genus.


Assuntos
Cianobactérias/classificação , Oceano Atlântico , Cianobactérias/citologia , Cianobactérias/genética , Cianobactérias/ultraestrutura , DNA Bacteriano/genética , Genes Bacterianos , Funções Verossimilhança , Fixação de Nitrogênio/genética , Filogenia , Portugal , RNA Ribossômico 16S/genética , Especificidade da Espécie
18.
Methods ; 112: 188-200, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-27223402

RESUMO

This review highlights the concepts and instrumentation of imaging flow cytometry technology and in particular its use for phytoplankton analysis. Imaging flow cytometry, a hybrid technology combining speed and statistical capabilities of flow cytometry with imaging features of microscopy, is rapidly advancing as a cell imaging platform that overcomes many of the limitations of current techniques and contributed significantly to the advancement of phytoplankton analysis in recent years. This review presents the various instrumentation relevant to the field and currently used for assessment of complex phytoplankton communities' composition and abundance, size structure determination, biovolume estimation, detection of harmful algal bloom species, evaluation of viability and metabolic activity and other applications. Also we present our data on viability and metabolic assessment of Aphanizomenon sp. cyanobacteria using Imagestream X Mark II imaging cytometer. Herein, we highlight the immense potential of imaging flow cytometry for microalgal research, but also discuss limitations and future developments.


Assuntos
Cianobactérias/ultraestrutura , Citometria de Fluxo/métodos , Citometria por Imagem/métodos , Fitoplâncton/ultraestrutura , Clorofila/química , Cianobactérias/metabolismo , Fluoresceínas/química , Corantes Fluorescentes/química , Proliferação Nociva de Algas/fisiologia , Fitoplâncton/metabolismo , Coloração e Rotulagem/métodos
19.
J Phycol ; 53(1): 188-197, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27809340

RESUMO

Cyanobacteria occupy many niches within terrestrial, planktonic, and benthic habitats. The diversity of habitats colonized, similarity of morphology, and phenotypic plasticity all contribute to the difficulty of cyanobacterial identification. An unknown marine filamentous cyanobacterium was isolated from an aquatic animal rearing facility having mysid mortality events. The cyanobacterium originated from Corpus Christi Bay, TX. Filaments are rarely solitary, benthic mat forming, unbranched, and narrowing at the ends. Cells are 2.1 × 3.1 µm (width × length). Thylakoids are peripherally arranged on the outer third of the cell; cyanophycin granules and polyphosphate bodies are present. Molecular phylogenetic analysis in addition to morphology (transmission electron microscopy and scanning electron microscopy) and chemical composition all confirm it as a new genus and species we name Toxifilum mysidocida. At least one identified Leptolyngbya appears (based on genetic evidence and TEM) to belong to this new genus.


Assuntos
Cianobactérias/classificação , Cianobactérias/genética , Cianobactérias/ultraestrutura , DNA Bacteriano/genética , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Tilacoides/ultraestrutura
20.
Dokl Biol Sci ; 470(1): 231-233, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27822760

RESUMO

Fossilized cyanobacteria(?) represented by trichomes enclosed in common sheaths were detected in early Proterozoic iron banded formations of the Kursk magnetic anomaly (limonite-martite ores of the Lebedinsky mine and iron banded formations of the Korobkovskoye deposit). These fossils morphologically similar to current representatives of the genus Microcoleus were buried in situ.


Assuntos
Cianobactérias/classificação , Cianobactérias/ultraestrutura , Óxido Ferroso-Férrico/análise , Fósseis/microbiologia , Fósseis/ultraestrutura , Cianobactérias/química , Óxido Ferroso-Férrico/química , Federação Russa , Especificidade da Espécie
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