90 research outputs found

    FEDSACE: A Framework for Enhanced user Data Security algorithms in Cloud Computing Environment

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    With technological advancements and constant changes of Internet, cloud computing has been today's trend. With the lower cost and convenience of cloud computing services, users have increasingly put their Web resources and information in the cloud environment. Increasing data volume is giving the bigger task of Data Centers to provide a better quality of cloud computing. The main usage of cloud computing is data storage. It is more reliable and flexible to users to store and retrieve their data at anytime and anywhere. the security of cloud computing plays a major role in the cloud computing, as customers often store important information with cloud storage providers but these providers may be unsafe. Customers are wondering about attacks on the integrity and the availability of their data in the cloud from malicious insiders and outsiders, and from any collateral damage of cloud services. These issues are extremely significant but there is still much room for security research in cloud computing. This paper presents a framework for global data security of the cloud with two-level Security model. The proposed framework is intended for adapting a system and the framework allows the network service provider to deploy a security in different data centers dynamically while the customers need more security for increasing the data storage

    An Antarctic molluscan biomineralisation tool-kit

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    Acknowledgements VAS was funded by a NERC DTG studentship (Project Reference: NE/J500173/1) to the British Antarctic Survey. MSC was financed by NERC core funding to the British Antarctic Survey. We would like to thank Jeremy Skepper for advising us on TEM procedures and processing the mantle tissue samples prior to TEM, Elizabeth M. Harper for advice on Laternula elliptica mantle anatomy for the schematic, Jamie Oliver for technical help with digitising the schematic, Deborah M. Power for in situ hybridisation advice, Valerie J. Smith for advice on immunology and histology, Lloyd S. Peck for vesicle discussions and critical reading of the manuscript and the dive team at Rothera research station, Antarctica for support in animal collection. Diving oversight was provided by the NERC National Facility for Scientific Diving, Oban.Peer reviewedPublisher PD

    Proteomic analysis of the organic matrix of the abalone Haliotis asinina calcified shell

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    Background: The formation of the molluscan shell is regulated to a large extent by a matrix of extracellular macromolecules that are secreted by the shell forming tissue, the mantle. This so called "calcifying matrix" is a complex mixture of proteins and glycoproteins that is assembled and occluded within the mineral phase during the calcification process. While the importance of the calcifying matrix to shell formation has long been appreciated, most of its protein components remain uncharacterised.Results: Recent expressed sequence tag (EST) investigations of the mantle tissue from the tropical abalone (Haliotis asinina) provide an opportunity to further characterise the proteins in the shell by a proteomic approach. In this study, we have identified a total of 14 proteins from distinct calcified layers of the shell. Only two of these proteins have been previously characterised from abalone shells. Among the novel proteins are several glutamine- and methionine-rich motifs and hydrophobic glycine-, alanine- and acidic aspartate-rich domains. In addition, two of the new proteins contained Kunitz-like and WAP (whey acidic protein) protease inhibitor domains.Conclusion: This is one of the first comprehensive proteomic study of a molluscan shell, and should provide a platform for further characterization of matrix protein functions and interactions

    Raman-probing the local ultrastrong coupling of vibrational plasmon-polaritons on metallic gratings

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    Strong coupling of molecular vibrations with light creates polariton states, enabling control over many optical and chemical properties. However, the near-field signatures of strong coupling are difficult to map as most cavities are closed systems. Surface-enhanced Raman microscopy of open metallic gratings under vibrational strong coupling enables the observation of spatial polariton localization in the grating near-field, without the need for scanning probe microscopies. The lower polariton is localized at the grating slots, displays a strongly asymmetric lineshape, and gives greater plasmon-vibration coupling strength than measured in the far-field. Within these slots, the local field strength pushes the system into the ultrastrong coupling regime. Models of strong coupling which explicitly include the spatial distribution of emitters can account for these effects. Such gratings form a new system for exploring the rich physics of polaritons and the interplay between their near- and far-field properties through polariton-enhanced Raman scattering (PERS)

    Raman Probing the Local Ultrastrong Coupling of Vibrational Plasmon Polaritons on Metallic Gratings

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    Strong coupling of molecular vibrations with light creates polariton states, enabling control over many optical and chemical properties. However, the near-field signatures of strong coupling are difficult to map as most cavities are closed systems. Surface-enhanced Raman microscopy of open metallic gratings under vibrational strong coupling enables the observation of spatial polariton localization in the grating near field, without the need for scanning probe microscopies. The lower polariton is localized at the grating slots, displays a strongly asymmetric line shape, and gives greater plasmon-vibration coupling strength than measured in the far field. Within these slots, the local field strength pushes the system into the ultrastrong coupling regime. Models of strong coupling which explicitly include the spatial distribution of emitters can account for these effects. Such gratings enable exploration of the rich physics of polaritons, its impact on polariton chemistry under flow conditions, and the interplay between near- and far-field properties through vibrational polariton-enhanced Raman scattering

    Characterisation of the mantle transcriptome and biomineralisation genes in the blunt-gaper clam, Mya truncata

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    Members of the Myidae family are ecologically and economically important, but there is currently very little molecular data on these species. The present study sequenced and assembled the mantle transcriptome of Mya truncata from the North West coast of Scotland and identified candidate biomineralisation genes. RNA-Seq reads were assembled to create 20,106 contigs in a de novo transciptome, 18.81% of which were assigned putative functions using BLAST sequence similarity searching (cuttoff E-value 1E − 10). The most highly expressed genes were compared to the Antarctic clam (Laternula elliptica) and showed that many of the dominant biological functions (muscle contraction, energy production, biomineralisation) in the mantle were conserved. There were however, differences in the constitutive expression of heat shock proteins, which were possibly due to the M. truncata sampling location being at a relatively low latitude, and hence relatively warm, in terms of the global distribution of the species. Phylogenetic analyses of the Tyrosinase proteins from M. truncata showed a gene expansion which was absent in L. elliptica. The tissue distribution expression patterns of putative biomineralisation genes were investigated using quantitative PCR, all genes showed a mantle specific expression pattern supporting their hypothesised role in shell secretion. The present study provides some preliminary insights into how clams from different environments – temperate versus polar – build their shells. In addition, the transcriptome data provides a valuable resource for future comparative studies investigating biomineralisation

    Shell matrix proteins of the clam, Mya truncata: Roles beyond shell formation through proteomic study

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    Mya truncata, a soft shell clam, is presented as a new model to study biomineralization through a proteomics approach. In this study, the shell and mantle tissue were analysed in order to retrieve knowledge about the secretion of shell matrix proteins (SMPs). Out of 67 and 127 shell and mantle proteins respectively, 16 were found in both shell and mantle. Bioinformatic analysis of SMP sequences for domain prediction revealed the presence of several new domains such as fucolectin tachylectin-4 pentraxin-1 (FTP), scavenger receptor, alpha-2-macroglobulin (α2 M), lipocalin and myosin tail along with previously reported SMP domains such as chitinase, carbonic anhydrase, tyrosinase, sushi, and chitin binding. Interestingly, these newly predicted domains are attributed with molecular functions other than biomineralization. These findings suggest that shells may not only act as protective armour from predatory action, but could also actively be related to other functions such as immunity. In this context, the roles of SMPs in biomineralization need to be looked in a new perspective

    Global Metabolomic Characterizations of Microcystis spp. Highlights Clonal Diversity in Natural Bloom-Forming Populations and Expands Metabolite Structural Diversity

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    Cyanobacteria are photosynthetic prokaryotes capable of synthesizing a large variety of secondary metabolites that exhibit significant bioactivity or toxicity. Microcystis constitutes one of the most common cyanobacterial genera, forming the intensive blooms that nowadays arise in freshwater ecosystems worldwide. Species in this genus can produce numerous cyanotoxins (i.e., toxic cyanobacterial metabolites), which can be harmful to human health and aquatic organisms. To better understand variations in cyanotoxin production between clones of Microcystis species, we investigated the diversity of 24 strains isolated from the same blooms or from different populations in various geographical areas. Strains were compared by genotyping with 16S-ITS fragment sequencing and metabolite chemotyping using LC ESI-qTOF mass spectrometry. While genotyping can help to discriminate among different species, the global metabolome analysis revealed clearly discriminating molecular profiles among strains. These profiles could be clustered primarily according to their global metabolite content, then according to their genotype, and finally according to their sampling location. A global molecular network of all metabolites produced by Microcystis species highlights the production of a wide set of chemically diverse metabolites, including a few microcystins, many aeruginosins, microginins, cyanopeptolins, and anabaenopeptins, together with a large set of unknown molecules. These components, which constitute the molecular biodiversity of Microcystis species, still need to be investigated in terms of their structure and potential bioactivites (e.g., toxicity)

    Idiosyncratic features in tRNAs participating in bacterial cell wall synthesis

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    The FemXWv aminoacyl transferase of Weissella viridescens initiates the synthesis of the side chain of peptidoglycan precursors by transferring l-Ala from Ala-tRNAAla to UDP-MurNAc-pentadepsipeptide. FemXWv is an attractive target for the development of novel antibiotics, since the side chain is essential for the last cross-linking step of peptidoglycan synthesis. Here, we show that FemXWv is highly specific for incorporation of l-Ala in vivo based on extensive analysis of the structure of peptidoglycan. Comparison of various natural and in vitro-transcribed tRNAs indicated that the specificity of FemXWv depends mainly upon the sequence of the tRNA although additional specificity determinants may include post-transcriptional modifications and recognition of the esterified amino acid. Site-directed mutagenesis identified cytosines in the G1–C72 and G2–C71 base pairs of the acceptor stem as critical for FemXWv activity in agreement with modeling of tRNAAla in the catalytic cavity of the enzyme. In contrast, semi-synthesis of Ala-tRNAAla harboring nucleotide substitutions in the G3–U70 wobble base pair showed that this main identity determinant of alanyl-tRNA synthetase is non-essential for FemXWv. The different modes of recognition of the acceptor stem indicate that specific inhibition of FemXWv could be achieved by targeting the distal portion of tRNAAla for the design of substrate analogues
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