scholarly journals Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacteriumAnabaenasp. PCC 7120

2015 ◽  
Vol 112 (32) ◽  
pp. E4458-E4464 ◽  
Author(s):  
Amin Omairi-Nasser ◽  
Vicente Mariscal ◽  
Jotham R. Austin ◽  
Robert Haselkorn
Keyword(s):  
Electron Tomography ◽  
Atmospheric Nitrogen ◽  
Channel Formation ◽  
Nitrogen Fixing ◽  
Vegetative Cells ◽  
Metabolite Exchange ◽  
Minor Part ◽  
A Minor ◽  
Pcc 7120

The filamentous nitrogen-fixing cyanobacteriumAnabaenasp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Severalfragene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N− media. Cryopreservation combined with electron tomography were used to investigate the role of threefragene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein.

THE ROLE OF ANTHROPONYMS IN THE SEMANTIC FIELD OF ARTISTIC WORKS

2019 ◽  
Vol 2019 (29) ◽  
pp. 66-77
Author(s):  
Lidiya Derbenyova
Keyword(s):  
Literary Work ◽  
Main Theme ◽  
Semantic Field ◽  
New Meanings ◽  
Minor Part ◽  
The One ◽  
A Minor ◽  
And Storage ◽  
Horizon Of Expectations

The article explores the role of antropoetonyms in the reader’s “horizon of expectation” formation. As a kind of “text in the text”, antropoetonyms are concentrating a large amount of information on a minor part of the text, reflecting the main theme of the work. As a “text” this class of poetonyms performs a number of functions: transmission and storage of information, generation of new meanings, the function of “cultural memory”, which explains the readers’ “horizon of expectations”. In analyzing the context of the literary work we should consider the function of antropoetonyms in vertical context (the link between artistic and other texts, and the groundwork system of culture), as well as in the context of the horizontal one (times’ connection realized in the communication chain from the word to the text; the author’s intention). In this aspect, the role of antropoetonyms in the structure of the literary text is extremely significant because antropoetonyms convey an associative nature, generating a complex mechanism of allusions. It’s an open fact that they always transmit information about the preceding text and suggest a double decoding. On the one hand, the recipient decodes this information, on the other – accepts this as a sort of hidden, “secret” sense.

scholarly journals Inactivation of a Heterocyst-Specific Invertase Indicates a Principal Role of Sucrose Catabolism in Heterocysts of Anabaena sp.

2010 ◽  
Vol 192 (20) ◽  
pp. 5526-5533 ◽  
Author(s):  
Rocío López-Igual ◽  
Enrique Flores ◽  
Antonia Herrero
Keyword(s):  
Fluorescent Protein ◽  
Northern Analysis ◽  
Filamentous Cyanobacterium ◽  
Nitrogen Deprivation ◽  
Vegetative Cells ◽  
Anabaena Sp ◽  
Green Fluorescent ◽  
Pcc 7120 ◽  
Diazotrophic Growth

ABSTRACT Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that carries out N2 fixation in specialized cells called heterocysts, which exchange nutrients and regulators with the filament's vegetative cells that perform the photosynthetic fixation of CO2. The Anabaena genome carries two genes coding for alkaline/neutral invertases, invA and invB. As shown by Northern analysis, both genes were expressed monocistronically and induced under nitrogen deprivation, although induction was stronger for invB than for invA. Whereas expression of an InvA-N-GFP fusion (green fluorescent protein [GFP] fused to the N terminus of the InvA protein [InvA-N]) was homogeneous along the cyanobacterial filament, consistent with the lack of dependence on HetR, expression of an InvB-N-GFP fusion upon combined nitrogen deprivation took place mainly in differentiating and mature heterocysts. In an hetR genetic background, the InvB-N-GFP fusion was strongly expressed all along the filament. An insertional mutant of invA could grow diazotrophically but was impaired in nifHDK induction and exhibited an increased frequency of heterocysts, suggesting a regulatory role of the invertase-mediated carbon flux in vegetative cells. In contrast, an invB mutant was strongly impaired in diazotrophic growth, showing a crucial role of sucrose catabolism mediated by the InvB invertase in the heterocysts.

Excavating Women: Towards an Engendered History of Archaeology (1998)

2008 ◽  
Author(s):  
Margarita Díaz-Andreu ◽  
Marie Louise Stig Sørensen
Keyword(s):  
Intellectual History ◽  
History Of Archaeology ◽  
Disciplinary History ◽  
The Usa ◽  
History Of ◽  
Minor Part ◽  
A Minor ◽  
Critical Historiography ◽  
Knowledge Claims

Gender archaeology has by now become a relatively well-established research topic within archaeology. Recent years have seen the publication of a number of edited volumes, a rapidly expanding number of papers, and even a few journals and newsletters dedicated to this subject. It is, therefore, very surprising that in this literature the historiographic analysis of women archaeologists has played only a minor part. Likewise they are hardly acknowledged in the ‘folk’ histories of the discipline (Lucy and Hill 1994: 2). The need to understand the disciplinary integration of women, to appreciate the varying socio-political contexts of their work, to reveal the unique tension between their roles as women and their academic lives, has become obvious and is strongly felt in many areas of the discipline. The insights yielded by such analysis will have significance at many levels and will be of paramount importance for the intellectual history of archaeology. In particular, such insights will necessitate a much-needed revision of disciplinary history by revealing its mechanisms of selecting and forgetting, and will play an important role in the analysis of archaeology’s knowledge claims. Histories of archaeology have broadly accepted, and spread, a perception of archaeology as being male-centred, both intellectually and in practice. These accounts, written by male archaeologists such as Glyn Daniel (1975), Alain Schnapp (1993), and Bruce Trigger (1989), are inevitably androcentric in their conceptualization and reconstruction of the disciplinary past. Their versions have, however, recently begun to be contested, as concern with critical historiography has grown, and a few explicit historiographical accounts of women archaeologists have appeared. So far, with regard to the role of women, the most extensive contributions are the edited volumes by Claassen (1994) and du Cros and Smith (1993). While providing an important beginning, these publications show that there is still a long way to go. In particular they demonstrate a gap in research coverage, as no investigation of the contribution of women outside the USA and Australia exists.

Solubility of the nadorite group minerals: implications for mobility of Sb and Bi in oxidised settings

2017 ◽  
Vol 14 (4) ◽  
pp. 224
Author(s):  
Adam J. Roper ◽  
Peter Leverett ◽  
Timothy D. Murphy ◽  
Peter A. Williams
Keyword(s):  
Redox Potential ◽  
Significant Role ◽  
Stability Studies ◽  
Secondary Minerals ◽  
Relative Stabilities ◽  
Mineral Phases ◽  
Minor Part ◽  
A Minor

Environmental contextThe dispersion of antimony in the environment has been misunderstood over the last few decades. Investigating the solubility of naturally forming mineral phases such as nadorite resulted in determination of its limited role in Sb dispersion, providing evidence that nadorite can only limit antimony dispersion in mildly oxidising conditions. Nadorite can only play a significant role in Sb immobilisation in a particular redox window, which forms only a minor part of the framework of Sb dispersion. AbstractAs part of a study of the control that secondary minerals exert on the dispersion of antimony and bismuth in the supergene environment, syntheses and stability studies of nadorite (PbSbO2Cl) and perite (PbBiO2Cl) have been undertaken. Solubilities in aqueous HNO3 were determined at 298.2K and the data obtained used to calculate values of ΔGfθ(298.2K). The ΔGfθ(s, 298.2K) values for PbSbO2Cl (–622.0±2.8kJmol–1) and PbBiO2Cl (–590.0±1.3kJmol–1) have been used in subsequent calculations to determine relative stabilities and relationships with other common secondary Sb and Bi minerals. While the role of nadorite in immobilising Sb is dependent upon the prevailing redox potential such that SbIII is stable, perite may be a significant phase in limiting the dispersion of Bi in certain supergene settings.

scholarly journals Thioredoxin targets are regulated in heterocysts of cyanobacterium Anabaena sp. PCC 7120 in a light-independent manner

2019 ◽  
Vol 71 (6) ◽  
pp. 2018-2027
Author(s):  
Shoko Mihara ◽  
Kazunori Sugiura ◽  
Keisuke Yoshida ◽  
Toru Hisabori
Keyword(s):  
Redox Regulation ◽  
Regulation System ◽  
Regulation Mechanism ◽  
Light Conditions ◽  
Nitrogen Fixing ◽  
Vegetative Cells ◽  
Target Proteins ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

Abstract In the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, glucose 6-phosphate dehydrogenase (G6PDH) plays an important role in producing the power for reducing nitrogenase under light conditions. Our previous study showed that thioredoxin suppresses G6PDH by reducing its activator protein OpcA, implying that G6PDH is inactivated under light conditions because thioredoxins are reduced by the photosynthetic electron transport system in cyanobacteria. To address how Anabaena sp. PCC 7120 maintains G6PDH activity even under light conditions when nitrogen fixation occurs, we investigated the redox regulation system in vegetative cells and specific nitrogen-fixing cells named heterocysts, individually. We found that thioredoxin target proteins were more oxidized in heterocysts than in vegetative cells under light conditions. Alterations in the redox regulation mechanism of heterocysts may affect the redox states of thioredoxin target proteins, including OpcA, so that G6PDH is activated in heterocysts even under light conditions.

scholarly journals Interactions of PatA with the Divisome during Heterocyst Differentiation in Anabaena

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Ana Valladares ◽  
Cristina Velázquez-Suárez ◽  
Antonia Herrero
Keyword(s):  
Cell Division ◽  
Organic Nitrogen ◽  
Atmospheric Nitrogen ◽  
Differentiation Process ◽  
Vegetative Cells ◽  
Genetic Changes ◽  
Heterocyst Differentiation ◽  
Essential Components ◽  
Z Ring

ABSTRACT The Anabaena organismic unit is a filament of communicating cells. Under conditions of nitrogen scarcity, some cells along the filament differentiate into heterocysts, which are specialized in the fixation of atmospheric N2 and provide the vegetative cells with N2 fixation products. At a certain stage, the differentiation process becomes irreversible, so that even when nitrogen is replenished, no return to the vegetative cell state takes place, possibly as a consequence of loss of cell division capacity. Upon N-stepdown, midcell FtsZ-rings were detected in vegetative cells, but not in differentiating cells, and this was also the case for ZipN, an essential protein that participates in FtsZ tethering to the cytoplasmic membrane and divisome organization. Later, expression of ftsZ was arrested in mature heterocysts. PatA is a protein required for the differentiation of intercalary heterocysts in Anabaena. The expression level of the patA gene was increased in differentiating cells, and a mutant strain lacking PatA exhibited enhanced FtsZ-rings. PatA was capable of direct interactions with ZipN and SepF, another essential component of the Anabaena Z-ring. Thus, PatA appears to promote inhibition of cell division in the differentiating cells, allowing progress of the differentiation process. PatA, which in mature heterocysts was detected at the cell poles, could interact also with SepJ, a protein involved in production of the septal junctions that provide cell-cell adhesion and intercellular communication in the filament, hinting at a further role of PatA in the formation or stability of the intercellular structures that are at the basis of the multicellular character of Anabaena. IMPORTANCE Anabaena is a cyanobacterial model that represents an ancient and simple form of biological multicellularity. The Anabaena organism is a filament of cohesive and communicating cells that can include cells specialized in different tasks. Thus, under conditions of nitrogen scarcity, certain cells of the filament differentiate into heterocysts, which fix atmospheric nitrogen and provide organic nitrogen to the rest of cells, which, in turn, provide heterocysts with organic carbon. Heterocyst differentiation involves extensive morphological, biochemical, and genetic changes, becoming irreversible at a certain stage. We studied the regulation during heterocyst differentiation of several essential components of the Anabaena cell division machinery and found that protein PatA, which is required for differentiation and is induced in differentiating cells, interacts with essential cell division factors and destabilizes the cell division complex. This suggests a mechanism for establishment of commitment to differentiation by inhibition of cell division.

scholarly journals The Etymology of Kallawaya

2017 ◽  
Vol 10 (2) ◽  
pp. 219-263 ◽  
Author(s):  
Katja Hannß
Keyword(s):  
Minor Part ◽  
A Minor

In this present paper, the etymological composition of Kallawaya, a mixed and secret language of Bolivia, will be discussed. I will argue that the lexicon of Kallawaya is more heterogeneous than has been assumed so far. In particular, the role of the allegedly main lexifier language Pukina will be critically re-assessed and I will suggest that only a minor part of the Kallawaya lexicon can be related to Pukina. The issues of secrecy and intentional borrowing will also be addressed.

scholarly journals Intercellular Diffusion of a Fluorescent Sucrose Analog via the Septal Junctions in a Filamentous Cyanobacterium

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Dennis J. Nürnberg ◽  
Vicente Mariscal ◽  
Jan Bornikoel ◽  
Mercedes Nieves-Morión ◽  
Norbert Krauß ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Cell Types ◽  
Cell Junctions ◽  
Filamentous Cyanobacterium ◽  
Nitrogen Fixing ◽  
Filamentous Cyanobacteria ◽  
Triple Mutant ◽  
Vegetative Cells ◽  
Metabolite Exchange ◽  
Import System

ABSTRACTMany filamentous cyanobacteria produce specialized nitrogen-fixing cells called heterocysts, which are located at semiregular intervals along the filament with about 10 to 20 photosynthetic vegetative cells in between. Nitrogen fixation in these complex multicellular bacteria depends on metabolite exchange between the two cell types, with the heterocysts supplying combined-nitrogen compounds but dependent on the vegetative cells for photosynthetically produced carbon compounds. Here, we used a fluorescent tracer to probe intercellular metabolite exchange in the filamentous heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120. We show that esculin, a fluorescent sucrose analog, is incorporated by a sucrose import system into the cytoplasm of Anabaena cells. The cytoplasmic esculin is rapidly and reversibly exchanged across vegetative-vegetative and vegetative-heterocyst cell junctions. Our measurements reveal the kinetics of esculin exchange and also show that intercellular metabolic communication is lost in a significant fraction of older heterocysts. SepJ, FraC, and FraD are proteins located at the intercellular septa and are suggested to form structures analogous to gap junctions. We show that a ΔsepJΔfraCΔfraDtriple mutant shows an altered septum structure with thinner septa but a denser peptidoglycan layer. Intercellular diffusion of esculin and fluorescein derivatives is impaired in this mutant, which also shows a greatly reduced frequency of nanopores in the intercellular septal cross walls. These findings suggest that FraC, FraD, and SepJ are important for the formation of junctional structures that constitute the major pathway for feeding heterocysts with sucrose.IMPORTANCEAnabaena and its relatives are filamentous cyanobacteria that exhibit a sophisticated form of prokaryotic multicellularity, with the formation of differentiated cell types, including normal photosynthetic cells and specialized nitrogen-fixing cells called heterocysts. The question of how heterocysts communicate and exchange metabolites with other cells in the filament is key to understanding this form of bacterial multicellularity. Here we provide the first information on the intercellular exchange of a physiologically important molecule, sucrose. We show that a fluorescent sucrose analog can be imported into the Anabaena cytoplasm by a sucrose import system. Once in the cytoplasm, it is rapidly and reversibly exchanged among all of the cells in the filament by diffusion across the septal junctions. Photosynthetically produced sucrose likely follows the same route from cytoplasm to cytoplasm. We identify some of the septal proteins involved in sucrose exchange, and our results indicate that these proteins form structures functionally analogous to metazoan gap junctions.

scholarly journals Involvement of Glutaredoxin and Thioredoxin Systems in the Nitrogen-Fixing Symbiosis between Legumes and Rhizobia

Antioxidants ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 182 ◽  
Author(s):  
Geneviève Alloing ◽  
Karine Mandon ◽  
Eric Boncompagni ◽  
Françoise Montrichard ◽  
Pierre Frendo
Keyword(s):  
Sinorhizobium Meliloti ◽  
Root Nodule ◽  
Redox Balance ◽  
Atmospheric Nitrogen ◽  
Nitrogen Fixing ◽  
Symbiotic Interaction ◽  
Bacterial Differentiation ◽  
Genes Encoding ◽  
Transcriptomics Data

Leguminous plants can form a symbiotic relationship with Rhizobium bacteria, during which plants provide bacteria with carbohydrates and an environment appropriate to their metabolism, in return for fixed atmospheric nitrogen. The symbiotic interaction leads to the formation of a new organ, the root nodule, where a coordinated differentiation of plant cells and bacteria occurs. The establishment and functioning of nitrogen-fixing symbiosis involves a redox control important for both the plant-bacteria crosstalk and the regulation of nodule metabolism. In this review, we discuss the involvement of thioredoxin and glutaredoxin systems in the two symbiotic partners during symbiosis. The crucial role of glutathione in redox balance and S-metabolism is presented. We also highlight the specific role of some thioredoxin and glutaredoxin systems in bacterial differentiation. Transcriptomics data concerning genes encoding components and targets of thioredoxin and glutaredoxin systems in connection with the developmental step of the nodule are also considered in the model system Medicago truncatula–Sinorhizobium meliloti.

scholarly journals The Heterocyst-Specific NsiR1 Small RNA Is an Early Marker of Cell Differentiation in Cyanobacterial Filaments

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Alicia M. Muro-Pastor
Keyword(s):  
Small Rna ◽  
Single Cells ◽  
Nitrogen Deficiency ◽  
Cell Types ◽  
Nitrogen Fixing ◽  
Vegetative Cells ◽  
Early Marker ◽  
Multicellular Organisms ◽  
Pcc 7120 ◽  
Different Cell Types

ABSTRACT Differentiation of single cells along filaments of cyanobacteria constitutes one of the simplest developmental patterns in nature. In response to nitrogen deficiency, certain cells located in a semiregular pattern along filaments differentiate into specialized nitrogen-fixing cells called heterocysts. The process involves the sequential activation of many genes whose expression takes place, either exclusively or at least more strongly, in those cells undergoing differentiation. In the model cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120, increased transcription of hetR, considered the earliest detectable heterocyst-specific transcript, has been reported to occur in pairs or even in clusters of cells, thus making it difficult to identify prospective heterocysts during the early stages of differentiation, before any morphological change is detectable. The promoter of nsiR1 (nitrogen stress inducible RNA1), a heterocyst-specific small RNA, constitutes a minimal sequence promoting heterocyst-specific transcription. Using confocal fluorescence microscopy, I have analyzed expression of a gfp reporter transcriptionally fused to P nsiR1 . The combined analysis of green fluorescence (reporting transcriptional activity from P nsiR1 ) and red fluorescence (an indication of progress in the differentiation of individual cells) shows that expression of P nsiR1 takes place in single cells located in a semiregular pattern before any other morphological or fluorescence signature of differentiation can be observed, thus providing an early marker for cells undergoing differentiation. IMPORTANCE Cyanobacterial filaments containing heterocysts constitute an example of bacterial division of labor. When using atmospheric nitrogen, these filaments behave as multicellular organisms in which two different cell types (vegetative cells and nitrogen-fixing heterocysts) coexist and cooperate to achieve growth of the filament as a whole. The molecular basis governing the differentiation of individual vegetative cells, and thus the establishment of a one-dimensional pattern from cells that are apparently the same, remains one of the most intriguing aspects of this differentiation process. Recent evidence suggests that, at any given time, some cells in the filaments are more likely than others to become heterocysts when nitrogen limitation is encountered. The robust heterocyst-specific nsiR1 promoter, which is induced very early during differentiation, provides a valuable tool to analyze issues such as early candidacy or the possible role of transcriptional noise in determining the fate of specific cells in cyanobacterial filaments.

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