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Sample records for aliivibrio salmonicida strain

  1. The genome sequence of the fish pathogen Aliivibrio salmonicida strain LFI1238 shows extensive evidence of gene decay

    PubMed Central

    Hjerde, Erik; Lorentzen, Marit Sjo; Holden, Matthew TG; Seeger, Kathy; Paulsen, Steinar; Bason, Nathalie; Churcher, Carol; Harris, David; Norbertczak, Halina; Quail, Michael A; Sanders, Suzanne; Thurston, Scott; Parkhill, Julian; Willassen, Nils Peder; Thomson, Nicholas R

    2008-01-01

    Background The fish pathogen Aliivibrio salmonicida is the causative agent of cold-water vibriosis in marine aquaculture. The Gram-negative bacterium causes tissue degradation, hemolysis and sepsis in vivo. Results In total, 4 286 protein coding sequences were identified, and the 4.6 Mb genome of A. salmonicida has a six partite architecture with two chromosomes and four plasmids. Sequence analysis revealed a highly fragmented genome structure caused by the insertion of an extensive number of insertion sequence (IS) elements. The IS elements can be related to important evolutionary events such as gene acquisition, gene loss and chromosomal rearrangements. New A. salmonicida functional capabilities that may have been aquired through horizontal DNA transfer include genes involved in iron-acquisition, and protein secretion and play potential roles in pathogenicity. On the other hand, the degeneration of 370 genes and consequent loss of specific functions suggest that A. salmonicida has a reduced metabolic and physiological capacity in comparison to related Vibrionaceae species. Conclusion Most prominent is the loss of several genes involved in the utilisation of the polysaccharide chitin. In particular, the disruption of three extracellular chitinases responsible for enzymatic breakdown of chitin makes A. salmonicida unable to grow on the polymer form of chitin. These, and other losses could restrict the variety of carrier organisms A. salmonicida can attach to, and associate with. Gene acquisition and gene loss may be related to the emergence of A. salmonicida as a fish pathogen. PMID:19099551

  2. IS elements in Aliivibrio salmonicida LFI1238: occurrence, variability and impact on adaptability.

    PubMed

    Kashulin, Alexander; Sørum, Henning; Hjerde, Erik; Willassen, Nils P

    2015-01-01

    Insertion sequence (IS) elements are short, self-replicating DNA sequences that are capable of efficiently spreading over the host genome. Possessing varied integration specificity IS elements are capable of the irreversible inactivation of genes, which diversifies the pool of intact genetic determinants in host populations. In the current study, we performed a complex analysis of IS elements (Vsa IS) in the previously sequenced genome of Aliivibrio salmonicida LFI1238 and proposed a model of the spread of the Vsa IS elements over the genome of this microorganism. Along with the prediction of the integration sites for Vsa IS elements, the current study provides an overview of the properties of A. salmonicida IS elements, as well as information regarding their occurrence in different bacterial classes. An analysis of individual alleles of the IS elements has allowed us to depict a history of the accumulation of mutations and to describe distinctive microevolution lines for actively transposing Vsa IS elements in the genome of A. salmonicida LFI1238. Our results demonstrate the high importance of the dead end microevolution of actively transposing Vsa IS elements for the inactivation of genes in A. salmonicida LFI1238. PMID:25447025

  3. Infection of sea lamprey with an unusual strain of Aeromonas salmonicida

    USGS Publications Warehouse

    Diamanka, Arfang; Loch, Thomas P.; Cipriano, Rocco C.; Winters, Andrew D.; Faisal, Mohamed

    2014-01-01

    The invasion of the Laurentian Great Lakes by the fish-parasitic sea lamprey has led to catastrophic consequences, including the potential introduction of fish pathogens. Aeromonas salmonicida is a bacterial fish pathogen that causes devastating losses worldwide. Currently, there are five accepted subspecies of Aeromonas salmonicida: A. salmonicida subsp. salmonicida, masoucida, smithia, achromogenes, and pectinolytica. We discuss the discovery of an isolate of A. salmonicida that is pathogenic to rainbow trout (Oncorhynchus mykiss) and exhibits unique phenotypic and molecular characteristics. We examined 181 adult sea lamprey (Petromyzon marinus) from the Humber River (Lake Ontario watershed) and 162 adult sea lamprey from Duffins Creek (Lake Ontario watershed) during the spring seasons of 2005–11. Among those, 4/343 (1.2%) sea lamprey were culture positive for A. salmonicida, whereby biochemical and molecular studies identified three of the isolates as A. salmonicida subsp. salmonicida. The remaining isolate (As-SL1) recovered from Humber River sea lamprey was phenotypically more similar to A. salmonicida subsp. salmonicida than to the four other A. salmonicida subspecies. However, unlike A. salmonicida subsp. salmonicida, As-SL1 was sucrose positive, produced an acid-over-acid reaction on triple-sugar iron medium and did not amplify with A. salmonicida subsp. salmonicida specific primers. Phylogenetic analysis based on partial stretches of the 16S rRNA and DNA gyrase subunit B genes further confirmed that the As-SL1 isolate was not A. salmonicida subsp. masoucida, smithia, achromogenes, or pectinolytica. Based on our analyses, the As-SL1 isolate is either an unusual strain of A. salmonicida subsp. salmonicida or a novel A. salmonicida subspecies. The four A. salmonicida isolates that were recovered from sea lamprey were pathogenic to rainbow trout in experimental challenge studies. Our study also underscores the potential role of sea lamprey in the ecology of

  4. Functional Genomics of the Aeromonas salmonicida Lipopolysaccharide O-Antigen and A-Layer from Typical and Atypical Strains

    PubMed Central

    Merino, Susana; de Mendoza, Elena; Canals, Rocío; Tomás, Juan M.

    2015-01-01

    The A. salmonicida A450 LPS O-antigen, encoded by the wbsalmo gene cluster, is exported through an ABC-2 transporter-dependent pathway. It represents the first example of an O-antigen LPS polysaccharide with three different monosaccharides in their repeating unit assembled by this pathway. Until now, only repeating units with one or two different monosaccharides have been described. Functional genomic analysis of this wbsalmo region is mostly in agreement with the LPS O-antigen structure of acetylated l-rhamnose (Rha), d-glucose (Glc), and 2-amino-2-deoxy-d-mannose (ManN). Between genes of the wbsalmo we found the genes responsible for the biosynthesis and assembly of the S-layer (named A-layer in these strains). Through comparative genomic analysis and in-frame deletions of some of the genes, we concluded that all the A. salmonicida typical and atypical strains, other than A. salmonicida subsp. pectinolytica strains, shared the same wbsalmo and presence of A-layer. A. salmonicida subsp. pectinolytica strains lack wbsalmo and A-layer, two major virulence factors, and this could be the reason they are the only ones not found as fish pathogens. PMID:26082990

  5. AsaGEI2b: a new variant of a genomic island identified in the Aeromonas salmonicida subsp. salmonicida JF3224 strain isolated from a wild fish in Switzerland.

    PubMed

    Emond-Rheault, Jean-Guillaume; Vincent, Antony T; Trudel, Mélanie V; Frey, Joachim; Frenette, Michel; Charette, Steve J

    2015-07-01

    Aeromonas salmonicida subsp. salmonicida is the causal agent of furunculosis in salmonids. We recently identified a group of genomic islands (AsaGEI) in this bacterium. AsaGEI2a, one of these genomic islands, has almost exclusively been identified in isolates from North America. To date, Aeromonas salmonicida subsp. salmonicida JF3224, a strain isolated from a wild brown trout (Salmo trutta) caught in Switzerland, was the only European isolate that appeared to bear AsaGEI2a. We analyzed the genome of JF3224 and showed that the genomic island in JF3224 is a new variant of AsaGEI, which we have called AsaGEI2b. While AsaGEI2b shares the same integrase gene and insertion site as AsaGEI2a, it is very different in terms of many other features. Additional genomic investigations combined with PCR genotyping revealed that JF3224 is sensitive to growth at 25°C, leading to insertion sequence-dependent rearrangement of the locus on the pAsa5 plasmid that encodes a type three secretion system, which is essential for the virulence of the bacterium. The analysis of the JF3224 genome confirmed that AsaGEIs are accurate indicators of the geographic origins of A. salmonicida subsp. salmonicida isolates and is another example of the susceptibility of the pAsa5 plasmid to DNA rearrangements. PMID:26048417

  6. Clustering subspecies of Aeromonas salmonicida using IS630 typing

    PubMed Central

    2013-01-01

    Background The insertion element IS630 found in Aeromonas salmonicida belongs to the IS630-Tc1-mariner superfamily of transposons. It is present in multiple copies and represents approximately half of the IS present in the genome of A. salmonicida subsp. salmonicida A449. Results By using High Copy Number IS630 Restriction Fragment Length Polymorphism (HCN-IS630-RFLP), strains of various subspecies of Aeromonas salmonicida showed conserved or clustering patterns, thus allowing their differentiation from each other. Fingerprints of A. salmonicida subsp. salmonicida showed the highest homogeneity while ‘atypical’ A. salmonicida strains were more heterogeneous. IS630 typing also differentiated A. salmonicida from other Aeromonas species. The copy number of IS630 in Aeromonas salmonicida ranges from 8 to 35 and is much lower in other Aeromonas species. Conclusions HCN-IS630-RFLP is a powerful tool for subtyping of A. salmonicida. The high stability of IS630 insertions in A. salmonicida subsp. salmonicida indicates that it might have played a role in pathoadaptation of A. salmonicida which has reached an optimal configuration in the highly virulent and specific fish pathogen A. salmonicida subsp. salmonicida. PMID:23406017

  7. Serological comparison of selected isolates of Aeromonas salmonicida ssp. Salmonicida

    USGS Publications Warehouse

    Hahnel, G.B.; Gould, R.W.; Boatman, E.S.

    1983-01-01

    Eight isolates of Acronionus salmonicida ssp. salmonicida were collected during furunculosis epizootics in North American Pacific coast states and provinces. Both virulent and avirulent forms of each isolate, confirmed by challenge and electron microscopy, were examined. Serological comparisons by cross-absorption agglutination tests revealed no serological differences between isolates. Using the double diffusion precipitin test, a single band was observed when antigen from a sonicated virulent strain was reacted with antiserum against a sonicated, virulent strain absorbed with homologous, avirulent strain. The presence of the single band was eliminated by excess sonication.

  8. Variants of a genomic island in Aeromonas salmonicida subsp. salmonicida link isolates with their geographical origins.

    PubMed

    Emond-Rheault, Jean-Guillaume; Vincent, Antony T; Trudel, Mélanie V; Brochu, Francis; Boyle, Brian; Tanaka, Katherine H; Attéré, Sabrina A; Jubinville, Éric; Loch, Thomas P; Winters, Andrew D; Faisal, Mohamed; Frenette, Michel; Derome, Nicolas; Charette, Steve J

    2015-01-30

    Aeromonas salmonicida subsp. salmonicida is a fish pathogen. Analysis of its genomic characteristics is required to determine the worldwide distribution of the various populations of this bacterium. Genomic alignments between the 01-B526 pathogenic strain and the A449 reference strain have revealed a 51-kb chromosomal insertion in 01-B526. This insertion (AsaGEI1a) has been identified as a new genomic island (GEI) bearing prophage genes. PCR assays were used to detect this GEI in a collection of 139 A. salmonicida subsp. salmonicida isolates. Three forms of this GEI (AsaGEI1a, AsaGEI1b, AsaGEI2a) are now known based on this analysis and the sequencing of the genomes of seven additional isolates. A new prophage (prophage 3) associated with AsaGEI2a was also discovered. Each GEI appeared to be strongly associated with a specific geographic region. AsaGEI1a and AsaGEI2a were exclusively found in North American isolates, except for one European isolate bearing AsaGEI2a. The majority of the isolates bearing AsaGEI1b or no GEI were from Europe. Prophage 3 has also a particular geographic distribution and was found only in North American isolates. We demonstrated that A. salmonicida subsp. salmonicida possesses unsuspected elements of genomic heterogeneity that could be used as indicators to determine the geographic origins of isolates of this bacterium. PMID:25480167

  9. Detection of Aeromonas salmonicida by reverse transcription-multiplex polymerase chain reaction.

    PubMed

    Rattanachaikunsopon, Pongsak; Phumkhachorn, Parichat

    2012-01-01

    Aeromonas salmonicida is one of the major fish pathogens causing economically devastating losses in aquaculture. A. salmonicida subsp. salmonicida is a typical A. salmonicida causing furunculosis, while the other subspecies are atypical strains causing ulcer diseases. PCR-based methods of detecting A. salmonicida suffer from the drawback that they do not distinguish living (pathogenic) from dead cells. In this study, a method of detecting A. salmonicida was developed based on reverse transcription-multiplex PCR (RT-MPCR) using two sets of primers, SV1/SV2 and SF1/SF2, specific to the vapA gene and the fstB gene of A. salmonicida respectively. This method was found to detect A. salmonicida specifically with detection limits of 10 CFU in pure culture and 30 CFU in the presence of tissue debris. It was also found distinguish not only between viable and nonviable cells but also between typical and atypical strains of A. salmonicida. Using RT-MPCR, two DNA fragments, of 542 and 1,258 bp, were amplified from RNA of typical A. salmonicida, whereas only one DNA fragment, of 542 bp, was amplified from the RNA of the atypical ones. The proposed assay was also used successfully to detect A. salmonicida in artificially infected rainbow trout (Oncorhyncus mykiss). PMID:22484927

  10. Biological control of Aeromonas salmonicida subsp. salmonicida infection in rainbow trout (Oncorhynchus mykiss) using Aeromonas phage PAS-1.

    PubMed

    Kim, J H; Choresca, C H; Shin, S P; Han, J E; Jun, J W; Park, S C

    2015-02-01

    The potential control efficacy of Aeromonas phage PAS-1 was evaluated against Aeromonas salmonicida subsp. salmonicida infection in rainbow trout (Oncorhynchus mykiss) model in this study. The phage was co-cultured with the virulent A. salmonicida subsp. salmonicida strain AS05 that possesses the type III secretion system (TTSS) ascV gene, and efficient bacteriolytic activity was observed against the bacteria. The administration of PAS-1 in rainbow trout demonstrated that the phage was cleared from the fish within 200 h post-administration, and a temporal neutralizing activity against the phage was detected in the sera of phage-administrated fish. The administration of PAS-1 (multiplicity of infection: 10 000) in A. salmonicida subsp. salmonicida infected rainbow trout model showed notable protective effects, with increased survival rates and mean times to death. These results demonstrated that Aeromonas phage PAS-1 could be considered as an alternative biological control agent against A. salmonicida subsp. salmonicida infections in rainbow trout culture. PMID:23594036

  11. Triclosan Resistance in a Bacterial Fish Pathogen, Aeromonas salmonicida subsp. salmonicida, is Mediated by an Enoyl Reductase, FabV.

    PubMed

    Khan, Raees; Lee, Myung Hwan; Joo, Hae-Jin; Jung, Yong-Hoon; Ahmad, Shabir; Choi, Jin-Hee; Lee, Seon-Woo

    2015-04-01

    Triclosan, the widely used biocide, specifically targets enoyl-acyl carrier protein reductase (ENR) in the bacterial fatty acid synthesis system. Although the fish pathogen Aeromonas salmonicida subsp. salmonicida exhibits triclosan resistance, the nature of this resistance has not been elucidated. Here, we aimed to characterize the triclosan resistance of A. salmonicida subsp. salmonicida causing furunculosis. The fosmid library of triclosan-resistant A. salmonicida subsp. salmonicida was constructed to select a fosmid clone showing triclosan resistance. With the fosmid clone showing triclosan resistance, a subsequent secondary library search resulted in the selection of subclone pTSR-1. DNA sequence analysis of pTSR-1 revealed the presence of a chromosomal-borne fabV-encoding ENR homolog. The ENR of A. salmonicida (FabVas) exhibited significant homology with previously known FabV, including the catalytic domain YX(8)K. fabVas introduction into E. coli dramatically increased its resistance to triclosan. Heterologous expression of FabVas might functionally replace the triclosan-sensitive FabI in vivo to confer E. coli with triclosan resistance. A genome-wide search for fabVas homologs revealed the presence of an additional fabV gene (fabVas2) paralog in A. salmonicida strains and the fabVas orthologs from other gram-negative fish pathogens. Both of the potential FabV ENRs expressed similarly with or without triclosan supplement. This is the first report about the presence of two potential FabV ENRs in a single pathogenic bacterium. Our result suggests that triclosan-resistant ENRs are widely distributed in various bacteria in nature, and the wide use of this biocide can spread these triclosan-tolerant ENRs among fish pathogens and other pathogenic bacteria. PMID:25370725

  12. Quantitative detection of Aeromonas salmonicida in fish tissue by real-time PCR using self-quenched, fluorogenic primers.

    PubMed

    Balcázar, José Luis; Vendrell, Daniel; de Blas, Ignacio; Ruiz-Zarzuela, Imanol; Gironés, Olivia; Múzquiz, José Luis

    2007-03-01

    In this study a real-time PCR assay using self-quenched primers labelled with a single fluorophore for the detection of Aeromonas salmonicida was developed. Probe specificity was confirmed by amplification of 16 A. salmonicida strain templates and by the lack of a PCR product with 26 non-A. salmonicida strains. With a pure culture of A. salmonicida, the assay was linear over a range of 0.5 pg to 50 ng and was able to detect 16 c.f.u. per reaction. A similar sensitivity was observed in DNA extracted from a mixture of A. salmonicida and fish tissue. Results using artificially inoculated tissues and diseased fish from outbreaks indicated that the assay can provide sensitive species-specific detection and quantification of A. salmonicida in fish tissue. PMID:17314361

  13. The Aeromonas salmonicida Lipopolysaccharide Core from Different Subspecies: The Unusual subsp. pectinolytica

    PubMed Central

    Merino, Susana; Tomás, Juan M.

    2016-01-01

    Initial hydridization tests using Aeromonas salmonicida typical and atypical strains showed the possibility of different lipopolysaccharide (LPS) outer cores among these strains. By chemical structural analysis, LPS-core SDS-PAGE gel migration, and functional and comparative genomics we demonstrated that typical A. salmonicida (subsp. salmonicida) strains and atypical subsp. masoucida and probably smithia strains showed the same LPS outer core. A. salmonicida subsp. achromogenes strains show a similar LPS outer core but lack one of the most external residues (a galactose linked α1-6 to heptose), not affecting the O-antigen LPS linkage. A. salmonicida subsp. pectinolytica strains show a rather changed LPS outer core, which is identical to the LPS outer core from the majority of the A. hydrophila strains studied by genomic analyses. The LPS inner core in all tested A. salmonicida strains, typical and atypical, is well-conserved. Furthermore, the LPS inner core seems to be conserved in all the Aeromonas (psychrophilic or mesophilic) strains studied by genomic analyses. PMID:26904002

  14. The Aeromonas salmonicida Lipopolysaccharide Core from Different Subspecies: The Unusual subsp. pectinolytica.

    PubMed

    Merino, Susana; Tomás, Juan M

    2016-01-01

    Initial hydridization tests using Aeromonas salmonicida typical and atypical strains showed the possibility of different lipopolysaccharide (LPS) outer cores among these strains. By chemical structural analysis, LPS-core SDS-PAGE gel migration, and functional and comparative genomics we demonstrated that typical A. salmonicida (subsp. salmonicida) strains and atypical subsp. masoucida and probably smithia strains showed the same LPS outer core. A. salmonicida subsp. achromogenes strains show a similar LPS outer core but lack one of the most external residues (a galactose linked α1-6 to heptose), not affecting the O-antigen LPS linkage. A. salmonicida subsp. pectinolytica strains show a rather changed LPS outer core, which is identical to the LPS outer core from the majority of the A. hydrophila strains studied by genomic analyses. The LPS inner core in all tested A. salmonicida strains, typical and atypical, is well-conserved. Furthermore, the LPS inner core seems to be conserved in all the Aeromonas (psychrophilic or mesophilic) strains studied by genomic analyses. PMID:26904002

  15. Polyphasic characterization of Aeromonas salmonicida isolates recovered from salmonid and non-salmonid fish

    USGS Publications Warehouse

    Diamanka, A.; Loch, T.P.; Cipriano, R.C.; Faisal, M.

    2013-01-01

    Michigan's fisheries rely primarily upon the hatchery propagation of salmonid fish for release in public waters. One limitation on the success of these efforts is the presence of bacterial pathogens, including Aeromonas salmonicida, the causative agent of furunculosis. This study was undertaken to determine the prevalence of A. salmonicida in Michigan fish, as well as to determine whether biochemical or gene sequence variability exists among Michigan isolates. A total of 2202 wild, feral and hatchery-propagated fish from Michigan were examined for the presence of A. salmonicida. The examined fish included Chinook salmon, Oncorhynchus tshawytscha (Walbaum), coho salmon, O. kisutcha (Walbaum), steelhead trout, O. mykiss (Walbaum), Atlantic salmon, Salmo salar L., brook trout, Salvelinus fontinalis (Mitchill), and yellow perch, Perca flavescens (Mitchill). Among these, 234 fish yielded a brown pigment-producing bacterium that was presumptively identified as A. salmonicida. Further phenotypic and phylogenetic analyses identified representative isolates as Aeromonas salmonicida subsp. salmonicida and revealed some genetic and biochemical variability. Logistic regression analyses showed that infection prevalence varied according to fish species/strain, year and gender, whereby Chinook salmon and females had the highest infection prevalence. Moreover, this pathogen was found in six fish species from eight sites, demonstrating its widespread nature within Michigan.

  16. Design of a toxicity biosensor based on Aliivibrio fischeri entrapped in a disposable card.

    PubMed

    Jouanneau, Sulivan; Durand-Thouand, Marie-José; Thouand, Gérald

    2016-03-01

    The degradation of the marine environment is a subject of concern for the European authorities primarily because of its contamination by hydrocarbons. The traditional methods (ISO 11348 standard) of general toxicity assessment are unsuitable in a context of in situ monitoring, such as seaports or bathing zones. Consequently, to address this issue, bacterial biosensors appear to be pertinent tools. This article presents the design of an innovative bioluminescent biosensor dedicated to in situ toxicity monitoring. This biosensor is based on the entrapment of the wild marine bioluminescent bacterial strain Aliivibrio fischeri ATCC® 49387™ in an agarose matrix within a disposable card. A pre-study was needed to select the most biological parameters. In particular, the regenerating medium's composition and the hydrogel concentration needed for the bacterial entrapment (mechanical resistance) were optimized. Based on these data, the ability of the bacterial reporter to assess the sample toxicity was demonstrated using naphthalene as a chemical model. The biosensor's results show a lower sensitivity to naphthalene (EC50 = 95 mg/L) compared with the results obtained using the reference method (EC50 = 43 mg/L). With this architecture, the biosensor is an interesting compromise among low maintenance, ease of use, appropriate sensitivity, relatively low cost and the ability to control online toxicity. PMID:26162438

  17. Insertion sequence AS5 (ISAS5) is involved in the genomic plasticity of Aeromonas salmonicida

    PubMed Central

    Trudel, Mélanie V.; Tanaka, Katherine H.; Filion, Geneviève; Daher, Rana K.; Frenette, Michel; Charette, Steve J.

    2013-01-01

    The genome of the fish pathogen Aeromonas salmonicida subsp salmonicida harbors a large number of insertion sequences (ISs), many of which are located on plasmids. In the present study, we analyzed the small plasmid profile of A. salmonicida strains to identify evidences of plasmid alterations. Ten out of 78 strains analyzed displayed an unconventional plasmid profile. However the HER1104 strain was unique, having a positive PCR signal for pAsal1 plasmid despite not carrying this plasmid. Instead, HER1104 was bearing a plasmid at higher molecular weight than pAsal1. We characterized this new larger plasmid, which we called pAsal1B since it is a derivative of pAsal1 containing one more complete IS (ISAS5) than the parental plasmid. An additional 96 bp relic of ISAS5 was also present in pAsal1B. These results propose that ISAS5 is another active mobile genetic element in A. salmonicida subsp salmonicida and provided further proof of the genomic plasticity of this bacterium. PMID:23956951

  18. Surface phenotypic characteristics and virulence of Spanish isolates of Aeromonas salmonicida after passage through fish.

    PubMed Central

    Fernández, A I; Pérez, M J; Rodríguez, L A; Nieto, T P

    1995-01-01

    Eleven strains of Aeromonas salmonicida were passaged twice by intraperitoneal injection through rainbow trout and reisolated from the kidney of moribund fish. The surface characteristics and virulence of the strains changed following passage through fish. None of the in vitro tests used could effectively predict the in vivo virulence. PMID:7646039

  19. Denaturing gradient gel electrophoresis for nonlethal detection of Aeromonas salmonicida in salmonid mucus and its potential for other bacterial fish pathogens.

    PubMed

    Quinn, Robert A; Stevenson, Roselynn M W

    2012-05-01

    Denaturing gradient gel electrophoresis (DGGE) of 16S rDNA was used to nonlethally detect Aeromonas salmonicida and other bacteria in salmonid skin mucus. Mucus samples from wild spawning coho salmon (Oncorhynchus kisutch) with endemic A. salmonicida and from cultured lake trout (Salvelinus namaycush) were tested by PCR-DGGE and were compared with mucus culture on Coomassie brilliant blue agar and internal organ culture. PCR-DGGE gave a highly reproducible 4-band pattern for 9 strains of typical A. salmonicida, which was different from other Aeromonas spp. Aeromonas salmonicida presence in mucus was evident as a band that comigrated with the bottom band of the A. salmonicida 4-band pattern and was verified by sequencing. PCR-DGGE found 36 of 52 coho salmon positive for A. salmonicida, compared with 31 positive by mucus culture and 16 by organ culture. Numerous other bacteria were detected in salmonid mucus, including Pseudomonas spp., Shewanella putrefaciens, Aeromonas hydrophila and other aeromonads. However, Yersinia ruckeri was not detected in mucus from 27 lake trout, but 1 fish had a sorbitol-positive Y. ruckeri isolated from organ culture. Yersinia ruckeri seeded into a mucus sample suggested that PCR-DGGE detection of this bacterium from mucus was possible. PCR-DGGE allows nonlethal detection of A. salmonicida in mucus and differentiation of some Aeromonas spp. and has the potential to allow simultaneous detection of other pathogens present in fish mucus. PMID:22506865

  20. Physical and functional S-layer reconstitution in Aeromonas salmonicida.

    PubMed Central

    Garduño, R A; Phipps, B M; Kay, W W

    1995-01-01

    The various functions attributed to the S-layer of Aeromonas salmonicida have been previously identified by their conspicuous absence in S-layer-defective mutants. As a different approach to establish the multifunctional nature of this S-layer, we established methods for reconstitution of the S-layer of A. salmonicida. Then we investigated the functional competence of the reconstituted S-layer. S-layers were reconstituted in different systems: on inert membranes or immobilized lipopolysaccharide (LPS) from purified S-layer protein (A-protein) or on viable cells from either A-protein or preassembled S-layer sheets. In the absence of divalent cations and LPS, purified A-protein in solution spontaneously assembled into tetrameric oligomers and, upon concentration by ultrafiltration, into macroscopic, semicrystalline sheets formed by oligomers loosely organized in a tetragonal arrangement. In the presence of Ca2+, purified A-protein assembled into normal tetragonal arrays of interlocked subunits. A-protein bound with high affinity (Kd, 1.55 x 10(-7) M) and specificity to high-molecular-weight LPS from A. salmonicida but not to the LPSs of several other bacterial species. In vivo, A-protein could be reconstituted only on A. salmonicida cells which contained LPS, and Ca2+ affected both a regular tetragonal organization of the reattached A-protein and an enhanced reattachment of the A-protein to the cell surface. The reconstitution of preformed S-layer sheets (produced by an S-layer-secreting mutant) to an S-layer-negative mutant occurred consistently and efficiently when the two mutant strains were cocultured on calcium-replete solid media. Reattached A-protein (exposed on the surface of S-layer-negative mutants) was able to bind porphyrins and an S-layer-specific phage but largely lacked regular organization, as judged by its inability to bind immunoglobulins. Reattached S-layer sheets were regularly organized and imparted the properties of porphyrin binding

  1. Aeromonas salmonicida subsp. salmonicida in the light of its type-three secretion system

    PubMed Central

    Vanden Bergh, Philippe; Frey, Joachim

    2014-01-01

    Aeromonas salmonicida subsp. salmonicida is an important pathogen in salmonid aquaculture and is responsible for the typical furunculosis. The type-three secretion system (T3SS) is a major virulence system. In this work, we review structure and function of this highly sophisticated nanosyringe in A. salmonicida. Based on the literature as well as personal experimental observations, we document the genetic (re)organization, expression regulation, anatomy, putative functional origin and roles in the infectious process of this T3SS. We propose a model of pathogenesis where A. salmonicida induces a temporary immunosuppression state in fish in order to acquire free access to host tissues. Finally, we highlight putative important therapeutic and vaccine strategies to prevent furunculosis of salmonid fish. PMID:24119189

  2. Aeromonas salmonicida subsp. salmonicida in the light of its type-three secretion system.

    PubMed

    Vanden Bergh, Philippe; Frey, Joachim

    2014-09-01

    Aeromonas salmonicida subsp. salmonicida is an important pathogen in salmonid aquaculture and is responsible for the typical furunculosis. The type-three secretion system (T3SS) is a major virulence system. In this work, we review structure and function of this highly sophisticated nanosyringe in A. salmonicida. Based on the literature as well as personal experimental observations, we document the genetic (re)organization, expression regulation, anatomy, putative functional origin and roles in the infectious process of this T3SS. We propose a model of pathogenesis where A. salmonicida induces a temporary immunosuppression state in fish in order to acquire free access to host tissues. Finally, we highlight putative important therapeutic and vaccine strategies to prevent furunculosis of salmonid fish. PMID:24119189

  3. Molecular characterization of tetracycline- and quinolone-resistant Aeromonas salmonicida isolated in Korea

    PubMed Central

    Kim, Ji Hyung; Hwang, Sun Young; Son, Jee Soo; Han, Jee Eun; Jun, Jin Woo; Shin, Sang Phil; Choresca, Casiano; Choi, Yun Jaie; Park, Yong Ho

    2011-01-01

    The antibiotic resistance of 16 Aeromonas (A.) salmonicida strains isolated from diseased fish and environmental samples in Korea from 2006 to 2009 were investigated in this study. Tetracycline or quinolone resistance was observed in eight and 16 of the isolates, respectively, based on the measured minimal inhibitory concentrations. Among the tetracycline-resistant strains, seven of the isolates harbored tetA gene and one isolate harbored tetE gene. Additionally, quinolone-resistance determining regions (QRDRs) consisting of the gyrA and parC genes were amplified and sequenced. Among the quinolone-resistant A. salmonicida strains, 15 harbored point mutations in the gyrA codon 83 which were responsible for the corresponding amino acid substitutions of Ser83→Arg83 or Ser83→Asn83. We detected no point mutations in other QRDRs, such as gyrA codons 87 and 92, and parC codons 80 and 84. Genetic similarity was assessed via pulsed-field gel electrophoresis, and the results indicated high clonality among the Korean antibiotic-resistant strains of A. salmonicida. PMID:21368562

  4. Draft genome sequences of two Aeromonas salmonicida subsp. salmonicida isolates harboring plasmids conferring antibiotic resistance.

    PubMed

    Vincent, Antony T; Tanaka, Katherine H; Trudel, Melanie V; Frenette, Michel; Derome, Nicolas; Charette, Steve J

    2015-02-01

    The bacterium Aeromonas salmonicida is the etiological agent of furunculosis, a widespread fish disease causing important economic losses to the fish farming industry. Antibiotic treatments in fish farms may be challenging given the existence of multidrug-resistant isolates of this bacterium. Here, we report the draft genome sequences of the 2004-05MF26 and 2009-144K3 isolates, which harbor plasmids conferring antibiotic resistance. Both isolates also carry the large plasmid pAsa5, which is known to encode a type three secretion system (TTSS) and the pAsal1 plasmid which has the aopP gene producing a TTSS effector. These two isolates are good representatives of the plasmid diversity in A. salmonicida subsp. salmonicida. PMID:25724776

  5. The improved PCR of the fstA (ferric siderophore receptor) gene differentiates the fish pathogen Aeromonas salmonicida from other Aeromonas species.

    PubMed

    Beaz-Hidalgo, Roxana; Latif-Eugenín, Fadua; Figueras, María José

    2013-10-25

    The members of the genus Aeromonas are autochthonous of aquatic ecosystems and several species have been associated to septicaemia, ulcerative and haemorrhagic diseases in fish, causing significant mortality in both wild and farmed, freshwater and marine fish species. The species Aeromonas salmonicida is generally recognized as the most important fish pathogen responsible for epidemic outbreaks of furunculosis in salmonids, also being able to produce infections in other cultured fish such as turbot, halibut, sea bream or goldfish. New species, i.e. Aeromonas aquariorum, Aeromonas tecta and Aeromonas piscicola, have recently been discovered and isolated from diseased fish. The species A. piscicola and Aeromonas bestiarum are practically impossible to differentiate phenotypically and genetically (when using the 16S rRNA gene) from each other and from A. salmonicida. In the present study, two previously described PCR protocols, based on the fstA and gyrB genes, for the specific detection of A. salmonicida were re-evaluated with the type strains of all Aeromonas species and with a set of A. piscicola and A. bestiarum strains. Contrary to what had been published previously it was demonstrated that the gyrB-PCR is not specific for A. salmonicida because of cross-reactions with other Aeromonas species. However, in agreement with previous results, A. salmonicida was detected on the basis of the fstA-PCR, for which an improved protocol was proposed. PMID:23890674

  6. Differential partition of virulent Aeromonas salmonicida and attenuated derivatives possessing specific cell surface alterations in polymer aqueous-phase systems

    NASA Technical Reports Server (NTRS)

    Van Alstine, J. M.; Trust, T. J.; Brooks, D. E.

    1986-01-01

    Two-polymer aqueous-phase systems in which partitioning of biological matter between the phases occurs according to surface properties such as hydrophobicity, charge, and lipid composition are used to compare the surface properties of strains of the fish pathogen Aeromonas salmonicida. The differential ability of strains to produce a surface protein array crucial to their virulence, the A layer, and to produce smooth lipopolysaccharide is found to be important in the partitioning behavior of Aeromonas salmonicida. The presence of the A layer is shown to decrease the surface hydrophilicity of the pathogen, and to increase specifically its surface affinity for fatty acid esters of polyethylene glycol. The method has application to the analysis of surface properties crucial to bacterial virulence, and to the selection of strains and mutants with specific surface characteristics.

  7. Aeromonas salmonicida: updates on an old acquaintance.

    PubMed

    Menanteau-Ledouble, Simon; Kumar, Gokhlesh; Saleh, Mona; El-Matbouli, Mansour

    2016-06-15

    Aeromonas salmonicida is the oldest known infectious agent to be linked to fish disease and constitutes a major bacterial pathogen of fish, in particular of salmonids. This bacterium can be found almost worldwide in both marine and freshwater environments and has been divided into several sub-species. In this review, we present the most recent developments concerning our understanding of this pathogen, including how the characterization of new isolates from non-salmonid hosts suggests a more nuanced picture of the importance of the so‑called 'atypical isolates'. We also describe the clinical presentation regarding the infection across several fish species and discuss what is known about the virulence of A. salmonicida and, in particular, the role that the type 3 secretion system might play in suppressing the immune response of its hosts. Finally, isolates have displayed varied levels of antibiotic resistance. Hence, we review a number of solutions that have been developed both to prevent outbreaks and to treat them once they occur, including the application of pre- and probiotic supplements. PMID:27304870

  8. Synthesis, characterization and toxicological evaluation of Cr₂O₃ nanoparticles using Daphnia magna and Aliivibrio fischeri.

    PubMed

    Puerari, Rodrigo Costa; da Costa, Cristina H; Vicentini, Denice S; Fuzinatto, Cristiane F; Melegari, Silvia P; Schmidt, Éder C; Bouzon, Zenilda L; Matias, William G

    2016-06-01

    Chromium III oxide (Cr2O3) nanoparticles (NPs) are used in pigments for ceramics, dyes, paints and cosmetics. However, few studies addressing the toxic potential of these NPs have been reported in the literature. Thus, this research aimed to evaluate the acute and chronic effects of Cr2O3 NPs through acute toxicity tests with Daphnia magna and Aliivibrio fischeri and chronic toxicity tests with Daphnia magna. Cr2O3 NPs were synthesized by the sol-gel method and characterized through TEM, X-Ray diffraction (XRD), zeta potential (ZP) and surface area analysis. In the acute toxicity tests the EC(50,48h) value obtained with D. magna was 6.79 mg L(-1) and for A. fischeri the EC(50,15min) value was 16.10 mg L(-1) and the EC(50,30min) value was 12.91 mg L(-1). Regarding the chronic toxicity tests with D. magna, effects on longevity (OEC=1.00 mg L(-1)), reproduction (OEC=1.00 mg L(-1)) and growth (OEC=0.50 mg L(-1)) were observed. On the SEM and TEM images, ultrastructural alterations in the organelles of exposed organisms were also observed. Thus, toxicological studies with NPs are of great importance in order to reduce the risk of environmental contamination. PMID:26890188

  9. Effect of Lactococcus lactis CLFP 100 and Leuconostoc mesenteroides CLFP 196 on Aeromonas salmonicida Infection in brown trout (Salmo trutta).

    PubMed

    Balcázar, José Luis; Vendrell, Daniel; de Blas, Ignacio; Ruiz-Zarzuela, Imanol; Múzquiz, José Luis

    2009-01-01

    Aeromonas salmonicida is the etiological agent of furunculosis in salmonid fish. This pathogen is important from an epizootic perspective because fish surviving an outbreak can remain lifelong asymptomatic carriers, serving as reservoirs of infection. As a result, the early detection and the control of infection are essential to prevent the spread of new furunculosis outbreaks. We have thus analyzed the effect of probiotic administration on the incidence of A. salmonicida in brown trout (Salmo trutta), that were subjected to temperature stress. Treatment with probiotic strains (Lactococcus lactis CLFP 100 and Leuconostoc mesenteroides CLFP 196) resulted in a higher survival rate after challenge, activation of phagocytic cells in the head kidney, and a lower rate of pathogen proliferation in the intestine as determined by real-time PCR. PMID:19556745

  10. The AsaP1 Peptidase of Aeromonas salmonicida subsp. achromogenes Is a Highly Conserved Deuterolysin Metalloprotease (Family M35) and a Major Virulence Factor▿

    PubMed Central

    Arnadottir, Helga; Hvanndal, Iris; Andresdottir, Valgerdur; Burr, Sarah E.; Frey, Joachim; Gudmundsdottir, Bjarnheidur K.

    2009-01-01

    Infections by the bacterium Aeromonas salmonicida subsp. achromogenes cause significant disease in a number of fish species. In this study, we showed that AsaP1, a toxic 19-kDa metallopeptidase produced by A. salmonicida subsp. achromogenes, belongs to the group of extracellular peptidases (Aeromonas type) (MEROPS ID M35.003) of the deuterolysin family of zinc-dependent aspzincin endopeptidases. The structural gene of AsaP1 was sequenced and found to be highly conserved among gram-negative bacteria. An isogenic ΔasaP1 A. salmonicida subsp. achromogenes strain was constructed, and its ability to infect fish was compared with that of the wild-type (wt) strain. The ΔasaP1 strain was found to infect Arctic charr, Atlantic salmon, and Atlantic cod, but its virulence was decreased relative to that of the wt strain. The 50% lethal dose of the AsaP1 mutant was 10-fold higher in charr and 5-fold higher in salmon than that of the wt strain. The pathology induced by the AsaP1-deficient strain was also different from that of the wt strain. Furthermore, the mutant established significant bacterial colonization in all observed organs without any signs of a host response in the infected tissue. AsaP1 is therefore the first member of the M35 family that has been shown to be a bacterial virulence factor. PMID:18952802

  11. The Aeromonas salmonicida subsp. salmonicida exoproteome: determination of the complete repertoire of Type-Three Secretion System effectors and identification of other virulence factors

    PubMed Central

    2013-01-01

    Background Aeromonas salmonicida subsp. salmonicida, the etiologic agent of furunculosis, is a major pathogen of fisheries worldwide. Several virulence factors have been described, but the type-three secretion system (T3SS) is recognized as having a major effect on virulence by injecting effectors directly into fish cells. In this study we used high-throughput proteomics to display the differences between in vitro secretome of A. salmonicida wild-type (wt, hypervirulent, JF2267) and T3SS-deficient (isogenic ΔascV, extremely low-virulent, JF2747) strains in exponential and stationary phases of growth. Results Results confirmed the secretion of effectors AopH, AexT, AopP and AopO via T3SS, and for the first time demonstrated the impact of T3SS in secretion of Ati2, AopN and ExsE that are known as effectors in other pathogens. Translocators, needle subunits, Ati1, and AscX were also secreted in supernatants (SNs) dependent on T3SS. AopH, Ati2, AexT, AopB and AopD were in the top seven most abundant excreted proteins. EF-G, EF-Tu, DnaK, HtpG, PNPase, PepN and MdeA were moderately secreted in wt SNs and predicted to be putative T3 effectors by bioinformatics. Pta and ASA_P5G088 were increased in wt SNs and T3-associated in other bacteria. Ten conserved cytoplasmic proteins were more abundant in wt SNs than in the ΔascV mutant, but without any clear association to a secretion system. T1-secreted proteins were predominantly found in wt SNs: OmpAI, OmpK40, DegQ, insulinase ASA_0716, hypothetical ASA_0852 and ASA_3619. Presence of T3SS components in pellets was clearly decreased by ascV deletion, while no impact was observed on T1- and T2SS. Our results demonstrated that the ΔascV mutant strain excreted well-described (VapA, AerA, AerB, GCAT, Pla1, PlaC, TagA, Ahe2, GbpA and enolase) and yet uncharacterized potential toxins, adhesins and enzymes as much as or even more than the wt strain. Other putative important virulence factors were not detected. Conclusions We

  12. Microencapsulated Aliivibrio fischeri in Alginate Microspheres for Monitoring Heavy Metal Toxicity in Environmental Waters

    PubMed Central

    Futra, Dedi; Heng, Lee Yook; Surif, Salmijah; Ahmad, Asmat; Ling, Tan Ling

    2014-01-01

    In this article a luminescence fiber optic biosensor for the microdetection of heavy metal toxicity in waters based on the marine bacterium Aliivibrio fischeri (A. fischeri) encapsulated in alginate microspheres is described. Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(II) were selected as sample toxic heavy metal ions for evaluation of the performance of this toxicity microbiosensor. The loss of bioluminescence response from immobilized A. fischeri bacterial cells corresponds to changes in the toxicity levels. The inhibition of the luminescent biosensor response collected at excitation and emission wavelengths of 287 ± 2 nm and 487 ± 2 nm, respectively, was found to be reproducible and repeatable within the relative standard deviation (RSD) range of 2.4–5.7% (n = 8). The toxicity biosensor based on alginate micropsheres exhibited a lower limit of detection (LOD) for Cu(II) (6.40 μg/L), Cd(II) (1.56 μg/L), Pb(II) (47 μg/L), Ag(I) (18 μg/L) than Zn(II) (320 μg/L), Cr(VI) (1,000 μg/L), Co(II) (1700 μg/L), Ni(II) (2800 μg/L), and Fe(III) (3100 μg/L). Such LOD values are lower when compared with other previous reported whole cell toxicity biosensors using agar gel, agarose gel and cellulose membrane biomatrices used for the immobilization of bacterial cells. The A. fischeri bacteria microencapsulated in alginate biopolymer could maintain their metabolic activity for a prolonged period of up to six weeks without any noticeable changes in the bioluminescence response. The bioluminescent biosensor could also be used for the determination of antagonistic toxicity levels for toxicant mixtures. A comparison of the results obtained by atomic absorption spectroscopy (AAS) and using the proposed luminescent A. fischeri-based biosensor suggests that the optical toxicity biosensor can be used for quantitative microdetermination of heavy metal toxicity in environmental water samples. PMID:25490588

  13. Microencapsulated Aliivibrio fischeri in alginate microspheres for monitoring heavy metal toxicity in environmental waters.

    PubMed

    Futra, Dedi; Heng, Lee Yook; Surif, Salmijah; Ahmad, Asmat; Ling, Tan Ling

    2014-01-01

    In this article a luminescence fiber optic biosensor for the microdetection of heavy metal toxicity in waters based on the marine bacterium Aliivibrio fischeri (A. fischeri) encapsulated in alginate microspheres is described. Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(II) were selected as sample toxic heavy metal ions for evaluation of the performance of this toxicity microbiosensor. The loss of bioluminescence response from immobilized A. fischeri bacterial cells corresponds to changes in the toxicity levels. The inhibition of the luminescent biosensor response collected at excitation and emission wavelengths of 287 ± 2 nm and 487 ± 2 nm, respectively, was found to be reproducible and repeatable within the relative standard deviation (RSD) range of 2.4-5.7% (n = 8). The toxicity biosensor based on alginate micropsheres exhibited a lower limit of detection (LOD) for Cu(II) (6.40 μg/L), Cd(II) (1.56 μg/L), Pb(II) (47 μg/L), Ag(I) (18 μg/L) than Zn(II) (320 μg/L), Cr(VI) (1,000 μg/L), Co(II) (1700 μg/L), Ni(II) (2800 μg/L), and Fe(III) (3100 μg/L). Such LOD values are lower when compared with other previous reported whole cell toxicity biosensors using agar gel, agarose gel and cellulose membrane biomatrices used for the immobilization of bacterial cells. The A. fischeri bacteria microencapsulated in alginate biopolymer could maintain their metabolic activity for a prolonged period of up to six weeks without any noticeable changes in the bioluminescence response. The bioluminescent biosensor could also be used for the determination of antagonistic toxicity levels for toxicant mixtures. A comparison of the results obtained by atomic absorption spectroscopy (AAS) and using the proposed luminescent A. fischeri-based biosensor suggests that the optical toxicity biosensor can be used for quantitative microdetermination of heavy metal toxicity in environmental water samples. PMID:25490588

  14. Development and evaluation of a multiplex PCR assay for simultaneous detection of Flavobacterium psychrophilum, Yersinia ruckeri and Aeromonas salmonicida subsp. salmonicida in culture fisheries.

    PubMed

    Onuk, Ertan Emek; Ciftci, Alper; Findik, Arzu; Durmaz, Yuksel

    2010-09-01

    Bacterial cold water disease, enteric red mouth disease and frunculosis are the common bacterial diseases of fish worldwide. The etiologic agents of these diseases are Flavobacterium (F.) psychrophilum, Yersinia (Y.) ruckeri and Aeromonas (A.) salmonicida subsp. salmonicida, respectively. In this study, a multiplex polymerase chain reaction (m-PCR) method with YER8/10-Fer3/4-FP1/3 primer pairs which can identify these fish pathogens simultaneously was developed and optimized. In optimized conditions, neither false specific nor nonspecific amplification occurred. The detection limits of the m-PCR method using DNA extracts from dilutions of pure cultures of bacteria were 35 pg for Y. ruckeri and F. psychrophilum and 70 pg for A. salmonicida subsp. salmonicida. It was determined that 15 CFU Y. ruckeri and F. psychrophilum and 30 CFU A. salmonicida subsp. salmonicida could be detected by m-PCR developed using genomic DNA extracted from dilutions of the suspensions. The detection limits in the presence of tissue debris were 125 CFU for Y. ruckeri and F. psychrophilum and 250 CFU for A. salmonicida subsp. salmonicida. In conclusion, we submit that the m-PCR method developed and optimized in this study can be used for accurate and rapid identification of these bacteria. PMID:20706031

  15. Development of a PCR protocol for the detection of Aeromonas salmonicida in fish by amplification of the fstA (ferric siderophore receptor) gene.

    PubMed

    Beaz-Hidalgo, Roxana; Magi, Gian Enrico; Balboa, Sabela; Barja, Juan L; Romalde, Jesús L

    2008-04-30

    The aims of the study were to evaluate a new PCR protocol designed to detect Aeromonas salmonicida in fish tissues and to develop a non-destructive method for the diagnosis of furunculosis. A set of primers (Fer3, Fer4), flanking a fragment of the fstA gene (coding for the ferric-siderophore receptor) was designed, showing to be sensitive and specific. When compared to PCR methods previously reported, the new protocol recognized all the 69 A. salmonicida strains evaluated, with no cross-reactions with the other bacterial species analysed. Sensitivity assays were performed in fish tissues seeded with serial dilutions of pure cultures of A. salmonicida and mixed cultures of this bacterium with Vibrio anguillarum and Aeromonas hydrophila. Detection limits obtained were of 60 and 450 bacterial cells 100 mg(-1) of tissue, respectively. Mucus and blood were evaluated in order to develop a non-destructive tool to detect the pathogen. The detection limits in seeded mucus and blood samples were 2.5 x 10(2) and 1 x 10(5) bacterial cells mL(-1), respectively. When the method was used to detect A. salmonicida in asymptomatic wild salmon, four samples of mucus and six of blood were positive, corresponding to 6 out of the 31 fish examined, whereas only one of the samples resulted positive by culture methods. It is concluded that the PCR protocol evaluated is fast, specific and sensitive to detect A. salmonicida in infected and asymptomatic fish, and will be helpful for the control of the disease through the prompt detection of carriers within fish populations. PMID:18035507

  16. QTL detection for Aeromonas salmonicida resistance related traits in turbot (Scophthalmus maximus)

    PubMed Central

    2011-01-01

    Background Interactions between fish and pathogens, that may be harmless under natural conditions, often result in serious diseases in aquaculture systems. This is especially important due to the fact that the strains used in aquaculture are derived from wild strains that may not have had enough time to adapt to new disease pressures. The turbot is one of the most promising European aquaculture species. Furunculosis, caused by the bacterium Aeromonas salmonicida, produces important losses to turbot industry. An appealing solution is to achieve more robust broodstock, which can prevent or diminish the devastating effects of epizooties. Genomics strategies have been developed in turbot to look for candidate genes for resistance to furunculosis and a genetic map with appropriate density to screen for genomic associations has been also constructed. In the present study, a genome scan for QTL affecting resistance and survival to A. salmonicida in four turbot families was carried out. The objectives were to identify consistent QTL using different statistical approaches (linear regression and maximum likelihood) and to locate the tightest associated markers for their application in genetic breeding strategies. Results Significant QTL for resistance were identified by the linear regression method in three linkage groups (LGs 4, 6 and 9) and for survival in two LGs (6 and 9). The maximum likelihood methodology identified QTL in three LGs (5, 6 and 9) for both traits. Significant association between disease traits and genotypes was detected for several markers, some of them explaining up to 17% of the phenotypic variance. We also identified candidate genes located in the detected QTL using data from previously mapped markers. Conclusions Several regions controlling resistance to A. salmonicida in turbot have been detected. The observed concordance between different statistical methods at particular linkage groups gives consistency to our results. The detected associated

  17. Effects of temperature on biochemical reactions and drug resistance of virulent and avirulent Aeromonas salmonicida

    USGS Publications Warehouse

    Hahnel, G.B.; Gould, R.W.

    1982-01-01

    Incubation temperatures of 11°, 18° and 28° did not substantially affect biochemical reactions of either virulent or avirulent forms of Aeromonas salmonicida subspecies salmonicida. The only change observed, amygdalin fermentation, was positive at 11° and 18° but negative at 28°C. Several isolates utilized sucrose, a characteristic not normally recognized for A. salmonicida subspecies salmonicida.Antimicrobial susceptibility screening indicated resistance to novobiocin increased at the higher incubation temperatures. Standardized drug sensitivity testing procedures and precise zone diameter interpretive standards for bacterial fish pathogens are needed.

  18. Diversity and Homogeneity among Small Plasmids of Aeromonas salmonicida subsp. salmonicida Linked with Geographical Origin

    PubMed Central

    Attéré, Sabrina A.; Vincent, Antony T.; Trudel, Mélanie V.; Chanut, Romain; Charette, Steve J.

    2015-01-01

    Furunculosis, which is caused by Aeromonas salmonicida subsp. salmonicida, is a major salmonid disease in fish farms worldwide. Several plasmids found in this bacterium confer phenotypes such drug resistance and virulence. Small plasmids (pAsa1, pAsa2, pAsa3, and pAsal1) related to ColE1- and ColE2-type replicons are usually present in its normal plasmidome. In the present study, with the objective to investigate if these plasmids display particularities related to the origin of the isolates bearing them, a total of 153 isolates, including 78 new and 75 previously described, were analyzed for the presence of small plasmids by PCR and DNA restriction fragment profiling. A geographical dichotomy between Canadian and European isolates for their propensity to do not have pAsa3 or pAsal1 was found. In addition, the genotyping analysis led to the identification of two European isolates harboring an unusual pAsal1. An investigation by next-generation sequencing (NGS) of these two isolates shed light on two pAsal1 variants (pAsal1C and pAsal1D). As with pAsal1B, another pAsal1 variant previously described, these two new variants bore a second insertion sequence (ISAS5) in addition to the usual ISAS11. The characterization of these variants suggested that they could predominate over the wild-type pAsal1 in stressful conditions such as growth at temperatures of 25°C and above. To obtain a comprehensive portrait of the mutational pressure on small plasmids, 26 isolates whose DNA had been sequenced by NGS were investigated. pAsa3 and pAsal1 were more prone to mutations than pAsa1 and pAsa2, especially in the mobA gene, which encodes a relaxase and a primase. Lastly, the average copy number of each plasmid per cell was assessed using raw sequencing data. A clear trend with respect to the relative proportion per cell of each plasmid was identified. Our large-scale study revealed a geographical dichotomy in small plasmid repertoire in addition to a clear trend for pAsa3 and p

  19. Diversity and Homogeneity among Small Plasmids of Aeromonas salmonicida subsp. salmonicida Linked with Geographical Origin.

    PubMed

    Attéré, Sabrina A; Vincent, Antony T; Trudel, Mélanie V; Chanut, Romain; Charette, Steve J

    2015-01-01

    Furunculosis, which is caused by Aeromonas salmonicida subsp. salmonicida, is a major salmonid disease in fish farms worldwide. Several plasmids found in this bacterium confer phenotypes such drug resistance and virulence. Small plasmids (pAsa1, pAsa2, pAsa3, and pAsal1) related to ColE1- and ColE2-type replicons are usually present in its normal plasmidome. In the present study, with the objective to investigate if these plasmids display particularities related to the origin of the isolates bearing them, a total of 153 isolates, including 78 new and 75 previously described, were analyzed for the presence of small plasmids by PCR and DNA restriction fragment profiling. A geographical dichotomy between Canadian and European isolates for their propensity to do not have pAsa3 or pAsal1 was found. In addition, the genotyping analysis led to the identification of two European isolates harboring an unusual pAsal1. An investigation by next-generation sequencing (NGS) of these two isolates shed light on two pAsal1 variants (pAsal1C and pAsal1D). As with pAsal1B, another pAsal1 variant previously described, these two new variants bore a second insertion sequence (ISAS5) in addition to the usual ISAS11. The characterization of these variants suggested that they could predominate over the wild-type pAsal1 in stressful conditions such as growth at temperatures of 25°C and above. To obtain a comprehensive portrait of the mutational pressure on small plasmids, 26 isolates whose DNA had been sequenced by NGS were investigated. pAsa3 and pAsal1 were more prone to mutations than pAsa1 and pAsa2, especially in the mobA gene, which encodes a relaxase and a primase. Lastly, the average copy number of each plasmid per cell was assessed using raw sequencing data. A clear trend with respect to the relative proportion per cell of each plasmid was identified. Our large-scale study revealed a geographical dichotomy in small plasmid repertoire in addition to a clear trend for pAsa3 and p

  20. Isolation of Aeromonas salmonicida from Human Blood Sample: A Case Report.

    PubMed

    Tewari, Rachna; Dudeja, Mridu; Nandy, Shyamasree; Das, Ayan Kumar

    2014-02-01

    Aeromonas salmonicida belonging to the genus Aeromonas, is a common pathogen that causes furunculosis and septicaemia in variety of fishes. It infects cold blooded vertebrates living at low temperatures mainly salmonid fish hence named salmonicida. Untill recently Aeromanas salmonicida is considered to be a fish pathogen. A. salmonicida is considered to be non-pathogenic for humans as it cannot grow at 37ºC. "However, In our laboratory culture plates and broths were incubated twice at 37ºC and each time same type of colonies were isolated which were identified as A. samonicida by Vitek 2 compact system bioMerieux, Inc. (Durham, N.C.)". By far no report has been received regarding its isolation from humans biological sample. Here we present the first report of A. salmonicida isolated from the human blood. PMID:24701507

  1. A toxicity assessment of 30 pharmaceuticals using Aliivibrio fischeri: a comparison of the acute effects of different formulations.

    PubMed

    Jacob, Raquel Sampaio; Santos, Lucilaine Valéria de Souza; de Souza, Ana Flávia Rodrigues; Lange, Liséte Celina

    2016-11-01

    Considerable quantities of different classes of drugs are consumed annually worldwide. These drugs, once disposed, often remain stable, even after conventional or advanced treatments. Although there have been a number of studies on the potential harm caused by drugs when released into the environment, few studies have investigated the toxicity of pharmaceutical excipients. In the present study, the acute toxicity of 30 drugs was tested to Aliivibrio fischeri. Ten different active ingredients were investigated, each in three distinct formulations: generic, similar and reference (brand drug). The aim of the study was to evaluate the harmful potential of drugs frequently sold in drugstores and to assess the contribution of excipients towards the observed acute toxicity. Within the 10 drugs evaluated, only one, dexchlorpheniramine maleate, was not toxic in any formulation. The toxicities of the three formulations were often different, even though the active ingredient has been the same. For some drugs, such as diazepam, glibenclamide, metformin, nimesulide, hydrochlorothiazide and simvastatin, only one or two of the three formulations tested were toxic to A. fischeri. These results highlight the toxicological potential of drug excipients, but not exclusively the toxicity of the active ingredients. PMID:27020342

  2. Detection of Variants of the pRAS3, pAB5S9, and pSN254 Plasmids in Aeromonas salmonicida subsp. salmonicida: Multidrug Resistance, Interspecies Exchanges, and Plasmid Reshaping

    PubMed Central

    Vincent, Antony T.; Trudel, Mélanie V.; Paquet, Valérie E.; Boyle, Brian; Tanaka, Katherine H.; Dallaire-Dufresne, Stéphanie; Daher, Rana K.; Frenette, Michel; Derome, Nicolas

    2014-01-01

    The ubiquitous water-borne Gram-negative bacterium Aeromonas salmonicida subsp. salmonicida is the causative agent of furunculosis, a worldwide disease in fish farms. Plasmids carrying antibiotic resistance genes have already been described for this bacterium. The aim of the present study was to identify and characterize additional multidrug resistance plasmids in A. salmonicida subsp. salmonicida. We sequenced the plasmids present in two multiple antibiotic-resistant isolates using high-throughput technologies. We also investigated 19 other isolates with various multidrug resistance profiles by genotyping PCR and assessed their resistance to tetracycline. We identified variants of the pAB5S9 and pSN254 plasmids that carry several antibiotic resistance genes and that have been previously reported in bacteria other than A. salmonicida subsp. salmonicida, which suggests a high level of interspecies exchange. Genotyping analyses and the antibiotic resistance profiles of the 19 other isolates support the idea that multiple versions of pAB5S9 and pSN254 exist in A. salmonicida subsp. salmonicida. We also identified variants of the pRAS3 plasmid. The present study revealed that A. salmonicida subsp. salmonicida harbors a wide variety of plasmids, which suggests that this ubiquitous bacterium may contribute to the spread of antibiotic resistance genes in the environment. PMID:25267667

  3. Detection of variants of the pRAS3, pAB5S9, and pSN254 plasmids in Aeromonas salmonicida subsp. salmonicida: multidrug resistance, interspecies exchanges, and plasmid reshaping.

    PubMed

    Vincent, Antony T; Trudel, Mélanie V; Paquet, Valérie E; Boyle, Brian; Tanaka, Katherine H; Dallaire-Dufresne, Stéphanie; Daher, Rana K; Frenette, Michel; Derome, Nicolas; Charette, Steve J

    2014-12-01

    The ubiquitous water-borne Gram-negative bacterium Aeromonas salmonicida subsp. salmonicida is the causative agent of furunculosis, a worldwide disease in fish farms. Plasmids carrying antibiotic resistance genes have already been described for this bacterium. The aim of the present study was to identify and characterize additional multidrug resistance plasmids in A. salmonicida subsp. salmonicida. We sequenced the plasmids present in two multiple antibiotic-resistant isolates using high-throughput technologies. We also investigated 19 other isolates with various multidrug resistance profiles by genotyping PCR and assessed their resistance to tetracycline. We identified variants of the pAB5S9 and pSN254 plasmids that carry several antibiotic resistance genes and that have been previously reported in bacteria other than A. salmonicida subsp. salmonicida, which suggests a high level of interspecies exchange. Genotyping analyses and the antibiotic resistance profiles of the 19 other isolates support the idea that multiple versions of pAB5S9 and pSN254 exist in A. salmonicida subsp. salmonicida. We also identified variants of the pRAS3 plasmid. The present study revealed that A. salmonicida subsp. salmonicida harbors a wide variety of plasmids, which suggests that this ubiquitous bacterium may contribute to the spread of antibiotic resistance genes in the environment. PMID:25267667

  4. Antibiotic resistance due to an unusual ColE1-type replicon plasmid in Aeromonas salmonicida.

    PubMed

    Vincent, Antony T; Emond-Rheault, Jean-Guillaume; Barbeau, Xavier; Attéré, Sabrina A; Frenette, Michel; Lagüe, Patrick; Charette, Steve J

    2016-06-01

    Aeromonas salmonicida subsp. salmonicida is a fish pathogen known to have a rich plasmidome. In the present study, we discovered an isolate of this bacterium bearing an additional unidentified small plasmid. After having sequenced the DNA of that isolate by next-generation sequencing, it appeared that the new small plasmid is a ColE1-type replicon plasmid, named here pAsa7. This plasmid bears a functional chloramphenicol-acetyltransferase-encoding gene (cat-pAsa7) previously unknown in A. salmonicida and responsible for resistance to chloramphenicol. A comparison of pAsa7 with pAsa2, the only known ColE1-type replicon plasmid usually found in A. salmonicida subsp. salmonicida, revealed that even if both plasmids share a high structural similarity, it is still unclear if pAsa7 is a derivative of pAsa2 since they showed several mutations at the nucleotide level. Transcriptomic analysis revealed that the cat-pAsa4 gene, another chloramphenicol-acetyltransferase-encoding gene, found on the large plasmid pAsa4, was significantly more transcribed than cat-pAsa7. This was correlated with a higher chloramphenicol resistance for isolates bearing pAsa4 compared with the one having pAsa7. Finally, a phylogenetic analysis showed that both CAT-pAsa4 and CAT-pAsa7 proteins were in different clusters. The clustering was supported by the identity of residues involved in the catalytic site. In addition, to give a better understanding of the large drug-resistance panel of A. salmonicida, this study reinforces the hypothesis that A. salmonicida subsp. salmonicida is a considerable reservoir for mobile genetic elements such as plasmids. PMID:27028891

  5. The Genome of Spironucleus salmonicida Highlights a Fish Pathogen Adapted to Fluctuating Environments

    PubMed Central

    Xu, Feifei; Jerlström-Hultqvist, Jon; Einarsson, Elin; Ástvaldsson, Ásgeir; Svärd, Staffan G.; Andersson, Jan O.

    2014-01-01

    Spironucleus salmonicida causes systemic infections in salmonid fish. It belongs to the group diplomonads, binucleated heterotrophic flagellates adapted to micro-aerobic environments. Recently we identified energy-producing hydrogenosomes in S. salmonicida. Here we present a genome analysis of the fish parasite with a focus on the comparison to the more studied diplomonad Giardia intestinalis. We annotated 8067 protein coding genes in the ∼12.9 Mbp S. salmonicida genome. Unlike G. intestinalis, promoter-like motifs were found upstream of genes which are correlated with gene expression, suggesting a more elaborate transcriptional regulation. S. salmonicida can utilise more carbohydrates as energy sources, has an extended amino acid and sulfur metabolism, and more enzymes involved in scavenging of reactive oxygen species compared to G. intestinalis. Both genomes have large families of cysteine-rich membrane proteins. A cluster analysis indicated large divergence of these families in the two diplomonads. Nevertheless, one of S. salmonicida cysteine-rich proteins was localised to the plasma membrane similar to G. intestinalis variant-surface proteins. We identified S. salmonicida homologs to cyst wall proteins and showed that one of these is functional when expressed in Giardia. This suggests that the fish parasite is transmitted as a cyst between hosts. The extended metabolic repertoire and more extensive gene regulation compared to G. intestinalis suggest that the fish parasite is more adapted to cope with environmental fluctuations. Our genome analyses indicate that S. salmonicida is a well-adapted pathogen that can colonize different sites in the host. PMID:24516394

  6. Immunohistochemical study of inducible nitric oxide synthase and tumour necrosis factor alpha response in turbot (Scophthalmus maximus) experimentally infected with Aeromonas salmonicida subsp. salmonicida.

    PubMed

    Coscelli, Germán; Bermúdez, Roberto; Ronza, Paolo; Losada, Ana Paula; Quiroga, María Isabel

    2016-09-01

    Aeromonas salmonicida subsp. salmonicida represents one of the major threats in aquaculture, especially in salmonid fish and turbot farming. In order to fight bacterial infections, fish have an immune system composed by innate and specific cellular and humoral elements analogous to those present in mammals. However, innate immunity plays a primordial role against bacterial infections in teleost fish. Among these non-specific mechanisms, the production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) pathway and the tumour necrosis factor-alpha (TNFα) produced by mononuclear phagocytes, are two of the main immune effectors to eliminate bacterial pathogens. In this study, the distribution and kinetic of iNOS and TNFα-producing cells of kidney and spleen of turbot experimentally inoculated with A. salmonicida was assessed by immunohistochemistry. In control and challenged fish, individual iNOS(+) and TNFα(+) cells, showing a similar pattern of distribution, were detected. In challenged fish, the number of immunoreactive cells was significantly increased in the evaluated organs, as well as the melanomacrophage centres showed variable positivity for both antigens. These results indicate that A. salmonicida induced an immune response in challenged turbot, which involved the increase of the activity of iNOS and TNFα in the leukocytic population from kidney and spleen. PMID:27431586

  7. Peroxide-inducible catalase in Aeromonas salmonicida subsp. salmonicida protects against exogenous hydrogen peroxide and killing by activated rainbow trout, Oncorhynchus mykiss L., macrophages.

    PubMed

    Barnes, A C; Bowden, T J; Horne, M T; Ellis, A E

    1999-03-01

    Aeromonas salmonicida subsp. salmonicida expresses a single cytoplasmically located catalase which was found to be inducible by exposure to 20 microM hydrogen peroxide in mid-exponential phase resulting in a 4 fold increase in activity. Subsequent exposure to 2 mM peroxide in late-exponential/early-stationary phase resulted in further induction of catalase activity which increased to 20 fold higher levels than those found in uninduced cultures. Exponentially induced cultures were protected against subsequent exposure to 10 mM peroxide which was lethal to non-induced cultures. Bacteria subjected to induction in mid-exponential and early-stationary phase were resistant to 100 mM peroxide, although viability was greatly reduced. Growth of the bacterium under iron-restricted conditions had no effect on the peroxide induction of catalase. As current evidence indicates, the latter is an iron-co-factored heme catalase, this result suggests that catalase induction has a high priority in the metabolism of iron. Furthermore, exposure to peroxide also induces expression of periplasmic MnSOD. A. salmonicida MT423 was resistant to normal rainbow trout macrophages, but was susceptible to killing by activated macrophages. However, if catalase was induced by prior exposure to 20 microM peroxide during mid-exponential phase, A. salmonicida was resistant to killing by activated macrophages. The ability of A. salmonicida to upregulate periplasmic MnSOD and cytoplasmic catalase production under iron restricted conditions and low level peroxide (conditions expected to exist during the early stages of an infection) may be vital for its ability to withstand attack by phagocytic cells in vivo. PMID:10089155

  8. Aeromonas salmonicida Ati2 is an effector protein of the type three secretion system.

    PubMed

    Dallaire-Dufresne, Stéphanie; Barbeau, Xavier; Sarty, Darren; Tanaka, Katherine H; Denoncourt, Alix M; Lagüe, Patrick; Reith, Michael E; Charette, Steve J

    2013-09-01

    The bacterium Aeromonas salmonicida, a fish pathogen, uses the type three secretion system (TTSS) to inject effector proteins into host cells to promote the infection. The study of the genome of A. salmonicida has revealed the existence of Ati2, a potential TTSS effector protein. In the present study, a structure-function analysis of Ati2 has been done to determine its role in the virulence of A. salmonicida. Biochemical assays revealed that Ati2 is secreted into the medium in a TTSS-dependent manner. Protein sequence analyses, molecular modelling and biochemical assays demonstrated that Ati2 is an inositol polyphosphate 5-phosphatase, which hydrolyses PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in a way similar to VPA0450, a protein from Vibrio parahaemolyticus having high sequence similarity with Ati2. Mutants of Ati2 with altered amino acids at two different locations in the catalytic site displayed no phosphatase activity. Wild-type and mutant forms of Ati2 were cloned into expression systems for Dictyostelium discoideum, a soil amoeba used as an alternative host to study A. salmonicida virulence. Expression tests allowed us to demonstrate that Ati2 is toxic for the host cell in a catalytic-dependent manner. Finally, this study demonstrated the existence of a new TTSS effector protein in A. salmonicida. PMID:23832001

  9. Living in an Extremely Polluted Environment: Clues from the Genome of Melanin-Producing Aeromonas salmonicida subsp. pectinolytica 34melT

    PubMed Central

    Pavan, María Elisa; Pavan, Esteban E.; López, Nancy I.; Levin, Laura

    2015-01-01

    Aeromonas salmonicida subsp. pectinolytica 34melT can be considered an extremophile due to the characteristics of the heavily polluted river from which it was isolated. While four subspecies of A. salmonicida are known fish pathogens, 34melT belongs to the only subspecies isolated solely from the environment. Genome analysis revealed a high metabolic versatility, the capability to cope with diverse stress agents, and the lack of several virulence factors found in pathogenic Aeromonas. The most relevant phenotypic characteristics of 34melT are pectin degradation, a distinctive trait of A. salmonicida subsp. pectinolytica, and melanin production. Genes coding for three pectate lyases were detected in a cluster, unique to this microorganism, that contains all genes needed for pectin degradation. Melanin synthesis in 34melT is hypothesized to occur through the homogentisate pathway, as no tyrosinases or laccases were detected and the homogentisate 1,2-dioxygenase gene is inactivated by a transposon insertion, leading to the accumulation of the melanin precursor homogentisate. Comparative genome analysis of other melanogenic Aeromonas strains revealed that this gene was inactivated by transposon insertions or point mutations, indicating that melanin biosynthesis in Aeromonas occurs through the homogentisate pathway. Horizontal gene transfer could have contributed to the adaptation of 34melT to a highly polluted environment, as 13 genomic islands were identified in its genome, some of them containing genes coding for fitness-related traits. Heavy metal resistance genes were also found, along with others associated with oxidative and nitrosative stresses. These characteristics, together with melanin production and the ability to use different substrates, may explain the ability of this microorganism to live in an extremely polluted environment. PMID:26025898

  10. Living in an Extremely Polluted Environment: Clues from the Genome of Melanin-Producing Aeromonas salmonicida subsp. pectinolytica 34melT.

    PubMed

    Pavan, María Elisa; Pavan, Esteban E; López, Nancy I; Levin, Laura; Pettinari, M Julia

    2015-08-01

    Aeromonas salmonicida subsp. pectinolytica 34mel(T) can be considered an extremophile due to the characteristics of the heavily polluted river from which it was isolated. While four subspecies of A. salmonicida are known fish pathogens, 34mel(T) belongs to the only subspecies isolated solely from the environment. Genome analysis revealed a high metabolic versatility, the capability to cope with diverse stress agents, and the lack of several virulence factors found in pathogenic Aeromonas. The most relevant phenotypic characteristics of 34mel(T) are pectin degradation, a distinctive trait of A. salmonicida subsp. pectinolytica, and melanin production. Genes coding for three pectate lyases were detected in a cluster, unique to this microorganism, that contains all genes needed for pectin degradation. Melanin synthesis in 34mel(T) is hypothesized to occur through the homogentisate pathway, as no tyrosinases or laccases were detected and the homogentisate 1,2-dioxygenase gene is inactivated by a transposon insertion, leading to the accumulation of the melanin precursor homogentisate. Comparative genome analysis of other melanogenic Aeromonas strains revealed that this gene was inactivated by transposon insertions or point mutations, indicating that melanin biosynthesis in Aeromonas occurs through the homogentisate pathway. Horizontal gene transfer could have contributed to the adaptation of 34mel(T) to a highly polluted environment, as 13 genomic islands were identified in its genome, some of them containing genes coding for fitness-related traits. Heavy metal resistance genes were also found, along with others associated with oxidative and nitrosative stresses. These characteristics, together with melanin production and the ability to use different substrates, may explain the ability of this microorganism to live in an extremely polluted environment. PMID:26025898

  11. Detection of the causative agent of furunculusis, Aeromonas salmonicida in salmonids of the Krka River.

    PubMed

    Kapetanović, D; Vardić, I; Kurtović, B; Valić, D; Teskeredzić, E

    2008-02-01

    In this paper we describe the bacterial community associated with salmonids from the Krka River. Diversity analysis demonstrated that majority of the recovered bacteria were related to Aeromonadaceae group. Bacterial analysis also revealed the presence of Shigella spp. and Pseudomonas fluorescens. Isolation of Aeromonas salmonicida from trout, presents first isolation of this bacteria Croatian rivers. PMID:17624808

  12. Evaluation of commercially prepared transport systems for nonlethal detection of Aeromonas salmonicida in salmonid fish

    USGS Publications Warehouse

    Cipriano, R.C.; Bullock, G.L.

    2001-01-01

    In vitro studies indicated that commercially prepared transport systems containing Amies, Stuart's, and Cary-Blair media worked equally well in sustaining the viability of the fish pathogen Aeromonas salmonicida, which causes furunculosis. The bacterium remained viable without significant increase or decrease in cell numbers for as long as 48 h of incubation at 18-20??C in Stuart's transport medium; consequently, obtaining mucus samples in such tubes were comparable to on-site detection of A. salmonicida by dilution plate counts on Coomassie Brilliant Blue agar. In three different assays of 100 samples of mucus from Atlantic salmon Salmo salar infected subclinically with A. salmonicida, dilution counts conducted on-site proved more reliable for detecting the pathogen than obtaining the samples in the transport system. In the on-site assays, dilution counts detected the pathogen in 34, 41, and 22 samples, whereas this was accomplished in only 15, 15, and 3 of the respective samples when the transport system was used. In an additional experiment, Arctic char Salvelinus alpinus sustaining a frank epizootic of furunculosis were sampled similarly. Here, too, dilution counts were more predictive of the prevalence of A. salmonicida and detected the pathogen in 46 mucus samples; in comparison, only 6 samples collected by using the transport system were positive. We also observed that the transport system supported the growth of the normal mucus bacterial flora. Particularly predominant among these were motile aeromonads and Pseudomonas fluorescens. In studies of mixed culture growth, two representatives of both of the latter genera of bacteria outgrew A. salmonicida - in some cases, to the total exclusion of the pathogen itself.

  13. Quarantine of Aeromonas salmonicida-harboring ebonyshell mussels (Fusconaia ebena) prevents transmission of the pathogen to brook trout (Salvelinus fontinalis)

    USGS Publications Warehouse

    Starliper, C.E.

    2005-01-01

    Furunculosis, caused by the bacterium Aeromonas salmonicida, was artificially induced in brook trout (Salvelinus fontinalis) in an experimental tank. Ebonyshells (Fusconaia ebena) were placed to cohabit with these fish to acquire the pathogen through siphoning. After 2 wk of cohabitation, 10 of the mussels were assayed by bacterial culture and all were found to harbor A. salmonicida. The mean cell count from soft tissue homogenates was 1.84 ?? 105 cfu/g, which comprised an average 14.41% of the total bacteria isolated from tissues. From the fluids, a mean of 2.84 ?? 105 A. salmonicida cfu/mL was isolated, which comprised an average of 17.29% of the total bacterial flora. The mussels were removed from the cohabitation tank and distributed equally among five previously disinfected tanks, 35 per tank. The F. ebena in each tank were allowed to depurate A. salmonicida for various durations: 1, 5, 10, 15 or 30 days. After each group had depurated for their assigned time, 10 were assayed for bacteria, tank water was tested, and 20 pathogen-free bioindicator brook trout were added to cohabit with the remaining mussels. Depuration was considered successful if A. salmonicida was not isolated from tank water or the mussels, and there was no infection or mortality to bioindicator fish. After 1 day of depuration, A. salmonicida was not isolated from the soft tissues; however, it was isolated from one of the paired fluids (10% prevalence). The tank water tested positive, and the bioindicator fish became infected and died. From the 5-day depuration group, A. salmonicida was not isolated from soft tissues, but was isolated from three fluids (30%; mean = 1.56 ?? 102 cfu/mL). Tank water from the 5-day group was negative, and there was no mortality among the bioindicator fish. However, A. salmonicida was isolated from 2 of 20 fish at the end of the 14-day observation period. One F. ebena fluid sample was positive for A. salmonicida from the 10-day depuration group, but none of the

  14. Aeromonas salmonicida binds differentially to mucins isolated from skin and intestinal regions of Atlantic salmon in an N-acetylneuraminic acid-dependent manner.

    PubMed

    Padra, János T; Sundh, Henrik; Jin, Chunsheng; Karlsson, Niclas G; Sundell, Kristina; Lindén, Sara K

    2014-12-01

    Aeromonas salmonicida subsp. salmonicida infection, also known as furunculosis disease, is associated with high morbidity and mortality in salmonid aquaculture. The first line of defense the pathogen encounters is the mucus layer, which is predominantly comprised of secreted mucins. Here we isolated and characterized mucins from the skin and intestinal tract of healthy Atlantic salmon and studied how A. salmonicida bound to them. The mucins from the skin, pyloric ceca, and proximal and distal intestine mainly consisted of mucins soluble in chaotropic agents. The mucin density and mucin glycan chain length from the skin were lower than were seen with mucin from the intestinal tract. A. salmonicida bound to the mucins isolated from the intestinal tract to a greater extent than to the skin mucins. The mucins from the intestinal regions had higher levels of sialylation than the skin mucins. Desialylating intestinal mucins decreased A. salmonicida binding, whereas desialylation of skin mucins resulted in complete loss of binding. In line with this, A. salmonicida also bound better to mammalian mucins with high levels of sialylation, and N-acetylneuraminic acid appeared to be the sialic acid whose presence was imperative for binding. Thus, sialylated structures are important for A. salmonicida binding, suggesting a pivotal role for sialylation in mucosal defense. The marked differences in sialylation as well as A. salmonicida binding between the skin and intestinal tract suggest interorgan differences in the host-pathogen interaction and in the mucin defense against A. salmonicida. PMID:25287918

  15. Precipitating antibody against Aeromonas salmonicida in serums of inbred albino Rainbow Trout (Salmo gairdneri)

    USGS Publications Warehouse

    Anderson, Douglas P.; Klontz, George W.

    1970-01-01

    Precipitins in albino rainbow trout serums were demonstrated by gel diffusion after a single parenteral exposure to the soluble antigens of Aeromonas salmonicida. The fraction of the serum containing antibody activity against the presented antigens was shown by immunoelectrophoresis to be in the nonmigrating region. This corresponded to the beta-2 fraction of rabbit serum. An antibody-containing component comparable with rabbit gamma globulin was not detected.

  16. Oceanivirga salmonicida gen. nov., sp. nov., a member of the Leptotrichiaceae isolated from Atlantic salmon (Salmo salar).

    PubMed

    Eisenberg, Tobias; Kämpfer, Peter; Ewers, Christa; Semmler, Torsten; Glaeser, Stefanie P; Collins, Evelyn; Ruttledge, Margaret; Palmer, Roy

    2016-06-01

    A pleomorphic, Gram-negative, rod-shaped, indole-, oxidase- and catalase- negative, non-spore-forming, non-motile bacterium was originally isolated in 1992 from moribund, seawater farmed Atlantic salmon with multifocal tissue necrosis. Strain AVG 2115T displayed considerable similarities with Streptobacillus moniliformis, one of the two etiological agents of rat bite fever, and has been stored as Streptobacillus sp. NCIMB 703044T. On the basis of 16S rRNA gene sequence analyses, this strain displayed >99 % sequence similarities with uncultured bacterial clones from the digestive tracts of marine mammals, followed by Sneathia sanguinegens CCUG 41628T (92.7 %), 'Sneathia amnii' Sn35 (92.5 %), Caviibacter abscessus CCUG 39713T (92.2 %), Streptobacillus ratti OGS16T (91.3 %), Streptobacillus notomytis AHL 370-1T (91.2 %), S. moniliformis DSM 12112T (91.0 %), Streptobacillus felis 131000547T (90.9 %) and Streptobacillus hongkongensis DSM 26322T (89.7 %). Sequence similarities to all other taxa were below 89 %. Phylogenetic analysis for strain NCIMB 703044T revealed highly similar results for gyrB, groEL and recA nucleotide and deduced amino acid sequence analyses independent of the employed treeing method. Average nucleotide identities (ANI) for complete genomes ranged from 66.00 % to 72.08 % between strain NCIMB 703044T and the type strains of Sebaldella termitidis, Leptotrichiabuccalis, Streptobacillus moniliformis, Sneathia sanguinegens and Caviibacter abscessus. Chemotaxonomic and physiological data of strain NCIMB 703044t were in congruence with closely related members of the family Leptotrichiaceae, represented by highly similar enzyme profiles and fatty acid patterns. MALDI-TOF MS analysis was capable to clearly discriminate strain NCIMB 703044T from all currently described taxa of the family Leptotrichiaceae. On the basis of these data we propose the novel taxon Oceanivirga salmonicida gen. nov. sp. nov. with the type strain AVG 2115T

  17. Development and validation of a real-time PCR assay for the detection of Aeromonas salmonicida.

    PubMed

    Keeling, S E; Brosnahan, C L; Johnston, C; Wallis, R; Gudkovs, N; McDonald, W L

    2013-05-01

    A real-time PCR assay using a molecular beacon was developed and validated to detect the vapA (surface array protein) gene in the fish pathogen, Aeromonas salmonicida. The assay had 100% analytical specificity and analytical sensitivities of 5 ± 0 fg (DNA), 2.2 × 10(4) ± 1 × 10(4) CFU g(-1) (without enrichment) and 40 ± 10 CFU g(-1) (with enrichment) in kidney tissue. The assay was highly repeatable and proved to be robust following equivalency testing using a different real-time PCR platform. Following analytical validation, diagnostic specificity was determined using New Zealand farmed Chinook salmon, Oncorhynchus tshawytscha (Walbaum), (n = 750) and pink shubunkin, Carassius auratus (L.) (n = 157). The real-time PCR was run in parallel with culture and all fish tested were found to be negative by both methods for A. salmonicida, resulting in 100% diagnostic specificity (95% confidence interval). The molecular beacon real-time PCR system is specific, sensitive and a reproducible method for the detection of A. salmonicida. It can be used for diagnostic testing, health certification and active surveillance programmes. PMID:23121198

  18. Growth inhibition of Aeromonas salmonicida and Yersinia ruckeri by disinfectants containing peracetic acid.

    PubMed

    Meinelt, Thomas; Phan, Thy-My; Behrens, Sascha; Wienke, Andreas; Pedersen, Lars-Flemming; Liu, Dibo; Straus, David L

    2015-04-01

    Peracetic acid (PAA) is a therapeutic agent used for disinfection in aquaculture, but it must be investigated thoroughly in order to mitigate diseases without harming the fish. Successful disinfectants (like PAA) should not leave dangerous residues in the environment in order to successfully contribute to sustainable aquaculture. The aim of our study was to compare the effectiveness of 6 commercial PAA products with different molecular PAA:H2O2 ratios to reduce bacterial growth of Aeromonas salmonicida and Yersinia ruckeri and to determine effective concentrations and exposure times. All products reduced colony-forming units (CFUs) of A. salmonicida and Y. ruckeri. Products with higher molecular PAA:H2O2 ratios inhibited growth better than products with lower molecular PAA:H2O2 ratios at the same PAA concentration; this indicates that H2O2 is not the driving force in the reduction of A. salmonicida and Y. ruckeri growth by PAA in vitro. The practical application of the products with high molecular PAA:H2O2 ratios should be prioritized if these pathogens are diagnosed. PMID:25850398

  19. Multiplex PCR for the detection of Piscirickettsia salmonis, Vibrio anguillarum, Aeromonas salmonicida and Streptococcus phocae in Chilean marine farms.

    PubMed

    Tapia-Cammas, D; Yañez, A; Arancibia, G; Toranzo, A E; Avendaño-Herrera, R

    2011-12-01

    A multiplex (m-)PCR-based protocol was designed for the simultaneous detection of the main marine bacterial pathogens in Chilean salmon farms: Streptococcus phocae, Aeromonas salmonicida, Vibrio anguillarum and Piscirickettsia salmonis. Each of the 4 oligonucleotide primer pairs exclusively amplified the target gene of the specific bacterial pathogen. The detection limit of the m-PCR using purified total bacterial DNA was 50 pg microl(-1) for V anguillarum, 500 fg microl(-1) for P. salmonis, and 5 pg microl(-1) for S. phocae and A. salmonicida. This corresponded to average limits in the m-PCR sensitivity of 3.69 x 10(5) CFU ml(-1) of V anguillarum, 1.26 x 10(4) CFU m(-1) of S. phocae, and 5.33 x 10(4) CFU ml(-1) of A. salmonicida, while the detection limits for the spiked fish tissues, regardless of the sample (spleen, kidney, liver or muscle) were 2.64 +/- 0.54 x 10(7) CFU g(-1) for V. anguillarum, 9.03 +/- 1.84 x 10(5) CFU g(-1) for S. phocae, 3.8 +/- 0.78 x 10(3) CFU mg(-1) for A. salmonicida and 100 P. salmonis cells. However, high amounts of DNA from 3 bacterial species had a reduction of -1 log-unit on the amplification sensitivity of S. phocae or A. salmonicida when these were present in lower concentration in the multiplex reaction. The assay described in this study is a rapid, sensitive and efficient tool to detect the presence of S. phocae, A. salmonicida, V. anguillarum and P. salmonis simultaneously from pure cultures and tissues from clinically diseased fish. Therefore, it may be a useful alternative to culture-based methods for the diagnosis of infections in fish obtained from Chilean salmon farms. PMID:22303630

  20. Historical record of Yersinia ruckeri and Aeromonas salmonicida among sea-run Atlantic salmon (Salmo salar) in the Penobscot River

    USGS Publications Warehouse

    Cipriano, R.C.; Coll, J.

    2005-01-01

    Despite restoration efforts, only about 2,000 Atlantic salmon (Salmo salar) salmon have annually returned to New England Rivers and more than 71% of these fish migrate to the Penobscot River alone. This report provides a historical compilation on the prevalence's of both Yersinia ruckeri, cause of enteric redmouth disease, and Aeromonas salmonicida, cause of furunculosis, among mature sea-run Atlantic salmon that returned to the Penobscot River from 1976 to 2003. Aeromonas salmonicida was detected in 28.6% and Yersinia ruckeri was detected among 50% of the yearly returns. Consequently, Atlantic salmon that return to the river are potential reservoirs of infection.

  1. Comparative evaluation of infection methods and environmental factors on challenge success: Aeromonas salmonicida infection in vaccinated rainbow trout.

    PubMed

    Chettri, Jiwan Kumar; Skov, Jakob; Jaafar, Rzgar M; Krossøy, Bjørn; Kania, Per W; Dalsgaard, Inger; Buchmann, Kurt

    2015-06-01

    When testing vaccine-induced protection an effective and reliable challenge method is a basic requirement and we here present a comparative study on different challenge methods used for infection of rainbow trout Oncorhynchus mykiss with Aeromonas salmonicida, a bacterial pathogen eliciting furunculosis. Fish were vaccinated with three different adjuvanted trivalent vaccines containing formalin killed A. salmonicida, Vibrio anguillarum O1 and O2a. These were 1) the commercial vaccine Alpha Ject 3000, 2) an experimental vaccine with water in paraffin oil adjuvant, 3) an experimental vaccine with water in paraffin oil in water adjuvant. Fish were then exposed to A. salmonicida challenge using i.p. injection, cohabitation in freshwater, cohabitation in saltwater (15 ppt) or combined fresh/saltwater cohabitation. Cohabitation reflects a more natural infection mode and was shown to give better differentiation of vaccine types compared to i.p. injection of live bacteria. The latter infection mode is less successful probably due to the intra-abdominal inflammatory reactions (characterized in this study according to the Speilberg scale) induced by i.p. vaccination whereby injected live bacteria more effectively become inactivated at the site of injection. Compared to cohabitation in freshwater, cohabitation in saltwater was less efficient probably due to reduced survivability of A. salmonicida in saltwater, which was also experimentally verified in vitro. PMID:25783001

  2. Survival of two bacterial fish pathogens (Aeromonas salmonicida and the Enteric Redmouth Bacterium) in ozonated, chlorinated, and untreated waters

    USGS Publications Warehouse

    Wedemeyer, Gary A.; Nelson, Nancy C.

    1977-01-01

    Ozone and chlorine inactivation curves were determined in three water types at 20 °C for the destruction of the fish pathogens Aeromonas salmonicida, the etiologic agent of furunculosis, and the enteric redmouth bacterium (ERM). In phosphate-buffered distilled water, 0.01 mg/ℓ ozone inactivated 103 cells/ml of ERM and A. salmonicida in 1/2 and 10 min, respectively. Chlorine at this concentration had little effect on either pathogen and a residual of at least 0.05 mg/ℓ was needed to achieve a complete kill within a 10-min contact time. In soft lake water (30 mg/ℓ as CaCO3) a chlorine residual of 0.1 mg/ℓ rapidly  inactivated A. salmonicida and ERM but in hard water (120 mg/ℓ) A. salmonicida was more resistant and 0.2 mg/ℓ chlorine was required. Ozonation of the two lake waters at 90 mg O3∙h−1∙ℓ−1 (equivalent to a 0.01 mg/ℓ residual in ozone demand-free water) was required to destroy both pathogens within 10 min.In untreated soft lake water 103 cells/ml of A. salmonicida survived only 2 days, while the ERM bacterium (103 cells/ml) survived even after 20 day s in soft and hard untreated lake waters.

  3. Development of a loop-mediated isothermal amplification assay for rapid detection of Nocardia salmonicida, the causative agent of nocardiosis in fish.

    PubMed

    Xia, Liqun; Zhang, Honglian; Lu, Yishan; Cai, Jia; Wang, Bei; Jian, Jichang

    2015-03-01

    Nocardia salmonicida is one of the main pathogens of fish nocardiosis. The purpose of this study was to build a loop-mediated isothermal amplification (LAMP) method for the rapid and sensitive detection of N. salmonicida. A set of four primers were designed from the 16S-23S rRNA intergenic spacer region of N. salmonicida, and conditions for LAMP were optimized as incubating all the reagents for 60 min at 64°C. LAMP products were judged with agar gel electrophoresis as well as with the naked eye after the addition of SYBR Green I. Results showed the sensitivity of the LAMP assay was 1.68 × 10(3) CFU/ml (16.8 CFU per reaction) and 10-fold higher than that of PCR. The LAMP method was also effectively applied to detect N. salmonicida in diseased fish samples, and it may potentially facilitate the surveillance and early diagnosis of fish nocardiosis. PMID:25262681

  4. Crystallization and preliminary X-ray diffraction analysis of a cold-adapted catalase from Vibrio salmonicida

    SciTech Connect

    Riise, Ellen Kristin; Lorentzen, Marit Sjo; Helland, Ronny; Willassen, Nils Peder

    2006-01-01

    Monoclinic (P2{sub 1}) crystals of a His-tagged form of V. salmonicida catalase without cofactor diffract X-rays to 1.96 Å. Catalase (EC 1.11.1.6) catalyses the breakdown of hydrogen peroxide to water and molecular oxygen. Recombinant Vibrio salmonicida catalase (VSC) possesses typical cold-adapted features, with higher catalytic efficiency, lower thermal stability and a lower temperature optimum than its mesophilic counterpart from Proteus mirabilis. Crystals of VSC were produced by the hanging-drop vapour-diffusion method using ammonium sulfate as precipitant. The crystals belong to the monoclinic space group P2{sub 1}, with unit-cell parameters a = 98.15, b = 217.76, c = 99.28 Å, β = 110.48°. Data were collected to 1.96 Å and a molecular-replacement solution was found with eight molecules in the asymmetric unit.

  5. Virulence and persistence of rough and smooth forms of Aeromonas salmonicida inoculated into coho salmon (Oncorhynchus kisutch)

    USGS Publications Warehouse

    Anderson, Douglas P.

    1972-01-01

    Virulent isolates of Aeromonas salmonicida showed a majority of smooth colonies, while the attenuated isolates displayed mostly rough colonies. A lesion occurred at the site of inoculation when one of the rough forms was inoculated into yearling coho salmon, but few mortalities were recorded even though the rough forms were readily recovered from both the lesion and the kidney. The fish inoculated with the same dosage of smooth forms all died within 96 hr of inoculation.

  6. Immunization of pacific salmon: comparison of intraperitoneal injection and hyperosmotic infiltration of Vibrio anguillarum and Aeromonas salmonicida bacterins

    USGS Publications Warehouse

    Antipa, Ross; Amend, Donald F.

    1977-01-01

    Two methods of immunizing fish, intraperitoneal (i.p.) injection and hyperosmotic infiltration, were compared for control of vibriosis and furunculosis in pen-reared coho salmon (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha). Both methods provided significant protection against vibriosis under field test conditions. In coho salmon, hyperosmotic infiltration provided the best protection and fastest rise in antibody titer of seven treatments tested. In chinook salmon, hyperosmotic infiltration of Vibrio anguillarum and Aeromonas salmonicida vaccines resulted in 83.3% survival in comparison with 28.7% survival in controls. Both i.p. injection and hyperosmotic infiltration of V. anguillarum and A. salmonicida bacterins resulted in production of serum antibodies specific for each respective pathogen. Vaccination with bivalent V. anguillarum–A.salmonicida vaccines produced antibodies to both pathogens, and provided protection against vibriosis. Growth rates of vaccinated coho salmon were not significantly different from controls.

  7. Adverse and long-term protective effects following oil-adjuvanted vaccination against Aeromonas salmonicida in rainbow trout.

    PubMed

    Villumsen, Kasper Rømer; Koppang, Erling Olaf; Raida, Martin Kristian

    2015-01-01

    Prophylactic measures against Aeromonas salmonicida subsp. salmonicida, the causative agent of furunculosis, have been an active field of research for decades, with studies mainly focused on Atlantic salmon (Salmo salar). In the present study we have examined the protective and adverse effects of mineral oil-adjuvanted injection vaccines on rainbow trout (Oncorhynchus mykiss). A commercial vaccine and an experimental auto vaccine, as well as their respective adjuvant formulations alone were used to evaluate their individual effects, both prior to and during an experimental waterborne infection challenge. Macro- and microscopic examination revealed signs of vaccine-induced adverse effects from 10 weeks to 14 months post vaccination. Both vaccines induced statistically significant protection during the experimental challenge (P=0.018 for both vaccines), as well as significantly elevated levels of specific circulating antibodies prior to and during the experimental challenge when compared to an unvaccinated control group. During the early, critical time points of the infection, both vaccines appeared to protect against pathological changes to the liver and spleen, which provides a probable explanation for the reduced mortality seen in the vaccinated groups. A significant correlation was found between the level of A. salmonicida-specific antibodies measured prior to challenge and the endpoint survival of each group after the experimental infection, and furthermore, the levels of these antibodies remained elevated for at least 14 months post vaccination. PMID:25281580

  8. Probiotic properties of Lactobacillus and Bifidobacterium strains isolated from porcine gastrointestinal tract.

    PubMed

    Kim, Pyoung Il; Jung, Min Young; Chang, Young-Hyo; Kim, Saehun; Kim, Seong-Jae; Park, Yong-Ha

    2007-04-01

    One strain of Lactobacillus salivarius, two strains of Lactobacillus reuteri and Lactobacillus amylovorus, and two strains of Bifidobacterium thermacidophilum with antagonistic effect against Clostridium perfringens were isolated from porcine gastrointestinal tract. Isolates were assayed for their ability to survive in synthetic gastric juice at pH 2.5 and were examined for their ability to grow on agar plate containing porcine bile extract. There was a large variation in the survival of the isolates in gastric juice and growth in the medium containing 0.3% (w/v) bile. L. salivarius G11 and L. amylovorus S6 adhered to the HT-29 epithelial cell line. Cell-free supernatant of L. amylovorus S6 showed higher antagonistic activity as effective as the antibiotics such as neomycin, chlortetracycline, and oxytetracycline against bacterial pathogens including C. perfringens, Salmonella typhimurium, Staphylococcus aureus, Vibrio cholerae, Edwardsiella tarda, and Aeromonas salmonicida subsp. salmonicida. PMID:17136367

  9. Aeromonas salmonicida infection levels in pre- and post-stocked cleaner fish assessed by culture and an amended qPCR assay.

    PubMed

    Gulla, S; Duodu, S; Nilsen, A; Fossen, I; Colquhoun, D J

    2016-07-01

    Due to increasing resistance to chemical therapeutants, the use of 'cleaner fish' (primarily wrasse, Labridae, species) has become popular in European salmon farming for biocontrol of the salmon louse, Lepeophtheirus salmonis (Krøyer). While being efficient de-licers, cleaner fish mortality levels in salmon cages are commonly high, and systemic bacterial infections constitute a major problem. Atypical furunculosis, caused by Aeromonas salmonicida A-layer types V and VI, is among the most common diagnoses reached in clinical investigations. A previously described real-time PCR (qPCR), targeting the A. salmonicida A-layer gene (vapA), was modified and validated for specific and sensitive detection of all presently recognized A-layer types of this bacterium. Before stocking and during episodes of increased mortality in salmon cages, cleaner fish (primarily wild-caught wrasse) were sampled and screened for A. salmonicida by qPCR and culture. Culture indicated that systemic bacterial infections are mainly contracted after salmon farm stocking, and qPCR revealed A. salmonicida prevalences of approximately 4% and 68% in pre- and post-stocked cleaner fish, respectively. This underpins A. salmonicida's relevance as a contributing factor to cleaner fish mortality and emphasizes the need for implementation of preventive measures (e.g. vaccination) if current levels of cleaner fish use are to be continued or expanded. PMID:26514414

  10. Effect of a phytogenic feed additive on the susceptibility of Onchorhynchus mykiss to Aeromonas salmonicida.

    PubMed

    Menanteau-Ledouble, S; Krauss, I; Santos, G; Fibi, S; Weber, B; El-Matbouli, M

    2015-06-29

    In recent years, feed additives have increasingly been adopted by the aquaculture industry. These supplements not only offer an alternative to antibiotics but have also been linked to enhanced growth performance. However, the literature is still limited and provides contradictory information on their effectiveness. This is mainly due to the wide variety of available products and their complex mechanisms of action. Phytogenic feed additives have been shown to have antimicrobial effects and can improve growth performance. In the present study, we investigated the susceptibility of several fish pathogenic bacteria to a phytogenic essential oil product in vitro. In addition, we determined the protective effect of a commercial phytogenic feed additive containing oregano, anis and citrus oils on the resistance of rainbow trout Oncorhynchus mykiss to infection by Aeromonas salmonicida. The bacterium was administered through 3 different routes: intra-peritoneal injection, immersion in a bacterial solution and cohabitation with infected fish. Mortality rates were significantly lower in infected rainbow trout that had received the feed additive: the overall mortality rate across all routes of infection was 18% in fish fed a diet containing the additive compared to 37% in fish that received unsupplemented feed. The route of infection also significantly impacted mortality, with average mortality rates of 60, 17.5 and 5% for intra-peritoneal injection, immersion and cohabitation, respectively. In general, fish were better protected against infection by immersion than infection by injection. PMID:26119300

  11. Ulcer disease prophylaxis in koi carp by bath immersion with chicken egg yolk containing anti-Aeromonas salmonicida IgY.

    PubMed

    Gan, Hongjian; He, Haiwen; Sato, Atsushi; Hatta, Hajime; Nakao, Miki; Somamoto, Tomonori

    2015-04-01

    Ulcer disease, caused by atypical Aeromonas salmonicida, is a serious concern in ornamental koi carp, because it induces skin ulceration, disfiguring ornamental fish and causing economic loses. The present study aimed to establish a novel prophylaxis with chicken egg yolk immunoglobulin, IgY, against ulcer disease and to assess its feasibility in the ornamental fish industry. Addition of egg yolk powder containing anti-A. salmonicida IgY to rearing water provided significant protection against an A. salmonicida bath infection, whereas administration of non-specific IgY did not. Consecutive immersion of fish into rearing water containing specific IgY completely prevented ulcer disease resulting from cohabitation infection, indicating that this prophylaxis could prevent infection from such type of contact. Thus, passive immunization induced by immersing fish into aquarium water containing specific IgY is a prospective prophylaxis against diseases caused by pathogens that invade the skin and gills. PMID:25687817

  12. The influence of dietary β-glucan, PAMP exposure and Aeromonas salmonicida on apoptosis modulation in common carp (Cyprinus carpio).

    PubMed

    Miest, J J; Falco, A; Pionnier, N P M; Frost, P; Irnazarow, I; Williams, G T; Hoole, D

    2012-10-01

    The association between β-glucan (MacroGard®) supplemented feed and apoptosis in immune-related organs of common carp (Cyprinus carpio) was studied using fluorescence microscopy and real-time PCR. In addition the effect of Aeromonas salmonicida, LPS and Poly(I:C) injections on this relationship was evaluated. Whilst acridine orange staining revealed that apoptosis levels were independent of MacroGard® and LPS/Poly(I:C) administration or their combination, it was shown that injection with A. salmonicida increased the percentage of apoptotic cells irrespective of the feeding regime. It was apparent that in all the treatments gene expression profiles displayed organ and time dependency. For example no effect was observed at 7 days of MacroGard® administration while 25 days of feeding led to increased iNOS expression and differential up-regulation of anti- or pro-apoptotic genes depending on organ. This may indicate differences in NO sensitivity. MacroGard® also led to an elevation of pro- as well as anti-apoptotic genes in LPS or Poly(I:C) injected fish, while LPS/Poly(I:C) alone had little effect. A. salmonicida caused enhanced iNOS expression and it is possible that the type of apoptosis pathway induced is organ dependent as Caspase 9 is induced in mid-gut but not in pronephros. These results indicate that MacroGard® feeding alone or in combination with other pathogenic factors did not induce significant apoptosis in immune organs. PMID:23198291

  13. Application of an immunoaffinity-based preconcentration method for mass spectrometric analysis of the O-chain polysaccharide of Aeromonas salmonicida from in vitro- and in vivo-grown cells.

    PubMed

    Wang, Zhan; Liu, Xin; Garduño, Elizabeth; Garduño, Rafael A; Li, Jianjun; Altman, Eleonora

    2009-06-01

    In this study, application of magnetic beads (Dynabeads) coated with Aeromonas salmonicida lipopolysaccharide-specific polyclonal antisera to MS-based characterization of bacterial lipopolysaccharides has been evaluated. The results showed that the affinity-based preconcentration strategy resulted in at least a 100-fold increase in the detection of sensitivity, affording direct capillary electrophoresis (CE)-MS analysis of A. salmonicida lipopolysaccharide O-chain polysaccharide from in vitro-cultured cells. Subsequent CE-MS analysis of in vivo-grown cells of A. salmonicida confirmed significant changes in the structure of the lipopolysaccharide O-chain polysaccharide as a result of in vivo cultivation. PMID:19456871

  14. Recovery of a fish pathogenic bacterium, Aeromonas salmonicida, from ebonyshell mussels Fusconaia ebena using nondestructive sample collection procedures

    USGS Publications Warehouse

    Starliper, C.E.

    2008-01-01

    Refugia are increasingly being used to maintain and propagate imperiled freshwater mussels for future population augmentations. Success for this endeavor is dependent on good husbandry, including a holistic program of resource health management. A significant aspect to optimal health is the prevention or control of infectious diseases. Describing and monitoring pathogens and diseases in mussels involves examination of tissues or samples collected from an appropriate number of individuals that satisfies a certain confidence level for expected prevalences of infections. In the present study, ebonyshell mussels Fusconaia ebena were infected with a fish pathogenic bacterium, Aeromonas salmonicida, through their cohabitation with diseased brook trout Salvelinus fontinalis. At a 100% prevalence of infection, the F. ebena were removed from the cohabitation tank to clean tanks that were supplied with pathogen-free water, which initiated their depuration of A. salmonicida. Three samples (nondestructive fluid, mantle, hemolymph) collected using nondestructive procedures were compared with fluids and soft tissue homogenates collected after sacrificing the mussels for recovery of the bacterium during this period of depuration. Nondestructive sample collections, especially ND fluid, provide a comparable alternative to sacrificing mussels to determine pathogen status.

  15. Reduced inflammatory response to Aeromonas salmonicida infection in common carp (Cyprinus carpio L.) fed with β-glucan supplements.

    PubMed

    Falco, Alberto; Frost, Patrick; Miest, Joanna; Pionnier, Nicolas; Irnazarow, Ilgiz; Hoole, David

    2012-06-01

    The objective of the present study was to determine the action of β-glucans as feed additives on the gene expression profile of some inflammatory-related cytokines from common carp (Cyprinus carpio L.) during the early stages of a non-lethal bacterial infection with Aeromonas salmonicida. β-glucan (MacroGard(®)), was administered daily to carp (6 mg per kg body weight) in the form of supplemented commercial food pellets for 14 days prior to infection. Control and treated fish were then intraperitoneally injected with PBS or 4×10(8) bacteria per fish and were sampled at time 0 and 6h, 12h, 1 day, 3 days and 5 days post-injection. Head kidney and gut were collected and the gene expression patterns for tnfα1, tnfα2, il1β, il6 and il10 were analyzed by quantitative PCR. Results obtained showed that treatment with β-glucans generally down-regulated the expression of all measured genes when compared to their corresponding controls. After injection, highest changes in the gene expression levels were obtained at 6h; particularly, in head kidney there was higher up-regulation of tnfa1 and tnfa2 in infected fish fed β-glucans in comparison to control feed; however, in gut there was a significant down-regulation of tnfα1, tnfα2, il1β and il6 in infected fish fed β-glucans. Analysis of carp specific antibodies against A. salmonicida 30 days after injection revealed their levels were reduced in the infected β-glucan group. In conclusion, a diet supplemented with β-glucan (MacroGard(®)) reduced the gene expression levels of some inflammation-related cytokines in common carp. Such a response appears to be dependent of organ studied and therefore the immunostimulant may be preventing an acute and potential dangerous response in gut, whilst enhancing the inflammatory response in head kidney when exposed to A. salmonicida. PMID:22406448

  16. The adjuvant effect of low frequency ultrasound when applied with an inactivated Aeromonas salmonicida vaccine to rainbow trout (Oncorhynchus mykiss).

    PubMed

    Cobo Labarca, Cristóbal; Makhutu, Mary; Lumsdon, Alexander E; Thompson, Kim D; Jung, Rainer; Kloas, Werner; Knopf, Klaus

    2015-03-10

    Vaccine adjuvants are classified according to their properties of either inducing the persistence of antigens within the animal after immunisation and/or activation of the animal's immune response. The adjuvant effect of low intensity low frequency sonophoresis (LFS) was tested in rainbow trout using an Aeromonas salmonicida bacterin vaccine administered by immersion vaccination using LFS at 37 kHz. The adjuvant effect obtained with LFS was compared with that of normal immersion or intraperitoneal injection vaccination. Quantitative PCR was used to measure bacterial DNA in vaccinated fish up to 35 days post-vaccination, while RT-qPCR was used to assess gene expression during the early and late immune response post-vaccination. Results showed that antigen uptake in the gills was significantly higher in the group exposed to low intensity LFS compared to the other two vaccination groups 15 min post-vaccination, but this initially high uptake did not persist over the rest of the experiment. In the kidney, by comparison, the vast majority of the samples analysed did not show the presence or persistence of the bacterin. Showing that the route of vaccine uptake using the A. salmonicida bacterin, does not influence the persistence of the bacterin in the gills or the kidney. On the other hand, LFS induced a higher inflammatory response and T-helper cell activation, characterized by a significant up-regulation of interleukin-8 (IL-8), IL-1ß and CD-4, respectively. The expression of Ig-M, Ig-T and Ig-D was up-regulated in gills (being significant for Ig-M), but not in the spleen and kidney of the sonicated group. Conversely, Ig-M was up-regulated in the spleen of the non-sonicated groups, but not in the sonicated group. This highlights the ability of ultrasound to enhance mucosal immunity. It remains to be established whether the up-regulation of Ig-M in gills would be sufficient to offer protection in fish infected with A. salmonicida. PMID:25613719

  17. Toll-like receptors in maraena whitefish: Evolutionary relationship among salmonid fishes and patterns of response to Aeromonas salmonicida.

    PubMed

    Altmann, Simone; Korytář, Tomáš; Kaczmarzyk, Danuta; Nipkow, Mareen; Kühn, Carsten; Goldammer, Tom; Rebl, Alexander

    2016-07-01

    Toll-like receptors (TLRs) interact directly with particular pathogenic structures and are thus highly important to innate immunity. The present manuscript characterises a suite of 14 TLRs in maraena whitefish (Coregonus maraena), a salmonid species with increasing importance for aquaculture. Whitefish TLRs were structurally and evolutionary analysed. The results revealed a close relationship with TLRs from salmonid fish species rainbow trout and Atlantic salmon. Profiling the baseline expression of TLR genes in whitefish indicated that mainly members of the TLR11 family were highly expressed across all investigated tissues. A stimulation model with inactivated Aeromonas salmonicida was used to induce inflammation in the peritoneal cavity of whitefish. This bacterial challenge induced the expression of pro-inflammatory cytokine genes and evoked a strong influx of granulated cells of myeloid origin into the peritoneal cavity. As a likely consequence, the abundance of TLR-encoding transcripts increased moderately in peritoneal cells, with the highest levels of transcripts encoding non-mammalian TLR22a and a soluble TLR5 variant. In the course of inflammation, the proportion of granulated cells increased in peripheral blood accompanied by elevated TLR copy numbers in spleen and simultaneously reduced TLR copy numbers in head kidney at day 3 post-stimulation. Altogether, the present study provides in-vivo evidence for relatively modest TLR response patterns, but marked trafficking of myeloid cells as an immunophysiological consequence of A. salmonicida inflammation in whitefish. The present results contribute to improved understanding of the host-pathogen interaction in salmonid fish. PMID:27131902

  18. Optimization of nested polymerase chain reaction assays for identification of Aeromonas salmonicida, Yersinia ruckeri and Flavobacterium psychrophilum

    USGS Publications Warehouse

    Taylor, P.W.; Winton, J.R.

    2002-01-01

    Nested polymerase chain reaction (PCR) assays were developed using first-round primers complementary to highly conserved regions within the bacterial 16S ribosomal RNA (rRNA) gene (universal eubacterial primers) and second-round primers specific for sequences within the 16S rRNA genes of Aeromonas salmonicida, Yersinia ruckeri, andFlavobacterium psychrophilum. Following optimization of the MgCl2 concentration and primer annealing temperature, PCR employing the universal eubacterial primers was used to amplify a 1,500-base-pair (bp) product visible in agarose gels stained with ethidium bromide. The calculated detection limit of this single-round assay was less than 1.4 × 104 colony-forming units (CFU) per reaction for all bacterial species tested. Single-round PCR using primer sets specific for A. salmonicida, Y. ruckeri, and F. psychrophilumamplified bands of 271, 575, and 1,100 bp, respectively, with detection limits of less than 1.4 × 104, 1.4 × 105, and 1.4 × 105 CFU per reaction. Using the universal eubacterial primers in the first round and the species-specific primer sets in the second round of nested PCR assays improved the detection ability by approximately four orders of magnitude to fewer than 14 CFU per sample for each of the three bacterial species. Such nested assays could be adapted to a wide variety of bacterial fish pathogens for which 16S sequences are available.

  19. Differences in detection of Aeromonas salmonicida in covertly infected salmonid fishes by the stress-inducible furunculosis test and culture-based assays

    USGS Publications Warehouse

    Cipriano, R.C.; Ford, L.A.; Smith, D.R.; Schachte, J.H.; Petrie, C.J.

    1997-01-01

    Accurate detection of Aeromonas salmonicida subsp. salmonicida (the cause of furunculosis disease) in covertly infected salmonids is difficult and is a cause of concern for those involved in fish health inspection and resource management programs. In this study, we examined populations of brook trout Salvelinus fontinalis, Atlantic salmon Salmo salar, and lake trout Salvelinus namaycush that previously sustained natural episodes of furunculosis. Consequently, the sampled fish were presumed to harbor latent infections. Mucus, gill, liver, kidney, heart, spleen, and intestine samples (N = 100 fish per group sampled) were processed and examined by (1) direct dilution counts and (2) quadrant streaking after a 48-h pre-enrichment in trypticase soy broth (TSB). Another subsample of fish from each group was then subjected to stress-inducible furunculosis tests. Stress tests detected A. salmonicida in three of four groups of fish that were examined whereas the pathogen was detected in only two of the groups analyzed with culture-based assays. Although pre-enrichment in TSB enhanced detection within internal sampling sites including the liver, heart, spleen, and kidney, enrichment did not enhance detection from mucus, gill, or intestinal samples.

  20. Bactericidal activity of juvenile chinook salmon macrophages against Aeromonas salmonicida after exposure to live or heat-killed Renibacterium salmoninarum or to soluble proteins produced by R. salmoninarum

    USGS Publications Warehouse

    Siegel, D.C.; Congleton, J.L.

    1997-01-01

    Macrophages isolated from the anterior kidney of juvenile chinook salmon Oncorhynchus tshawytscha in 96-well microtiter plates were exposed for 72 h to 0, 105, or 106 live or heat-killed Renibacterium salmoninarum cells per well or to 0, 0.1, 1.0, or 10 ??g/mL of R. salmoninarum soluble proteins. After treatment, the bactericidal activity of the macrophages against Aerornonas salmonicida was determined by a colorimetric assay based on the reduction of the tetrazolium dye MTT to formazan by viable bacteria. The MTT assay was modified to allow estimation of the percentage of bacteria killed by reference to a standard curve relating the number of bacteria added to microtiter wells to absorbance by formazan at 600 nm. The live and heat-killed R. salmoninarum treatments significantly (P < 0.001) increased killing of A. salmonicida by chinook salmon macrophages. In each of the five trials, significantly (P < 0.05) greater increases in killing occurred after exposure to 105 R. salmoninarum cells than to 106 R. salmoninarum cells per well. In contrast, treatment of macrophages with 10 ??g/mL R. salmoninarum soluble proteins significantly (P < 0.001) decreased killing of A. salmonicida, but treatment with lower doses did not. These results show that the bactericidal activity of chinook salmon macrophages is stimulated by exposure to R. salmoninarum cells at lower dose levels but inhibited by exposure to R. salmoninarum cells or soluble proteins at higher dose levels.

  1. Transcription Factor T-Bet in Atlantic Salmon: Characterization and Gene Expression in Mucosal Tissues during Aeromonas Salmonicida Infection

    PubMed Central

    Kumari, Jaya; Zhang, Zuobing; Swain, Trilochan; Chi, Heng; Niu, Cuijuan; Bøgwald, Jarl; Dalmo, Roy Ambli

    2015-01-01

    The T-box transcription factor T-bet is expressed in a number of hematopoietic cell types in mammals and plays an essential role in the lineage determination of Th1 T-helper cells and is considered as an essential feature for both innate and adaptive immune responses in higher vertebrates. In the present study, we have identified and characterized the full-length Atlantic salmon T-bet cDNA (3502 bp). The putative primary structure of the polypeptide deduced from the cDNA sequence contained 612 aa, which possessed a T-box DNA binding domain. Phylogenetic study and gene synteny revealed it is as a homolog to mammalian T-bet. Quantitative PCR analysis of different tissues in healthy fish showed that salmon T-bet gene was highly expressed in spleen, followed by head kidney, and was expressed in intestine, skin, and liver at lower levels. Moreover, the time-dependent expression profile of T-bet, interferon gamma (IFNγ), interleukin-22 (IL-22), and natural killer enhancement factor in mucosal tissues during water-borne infection with live Aeromonas salmonicida, indicated the involvement of T-bet in mucosal immune response in Atlantic salmon. PMID:26217339

  2. Effects of dietary linseed oil on innate immune system of Eurasian perch and disease resistance after exposure to Aeromonas salmonicida achromogen.

    PubMed

    Geay, F; Mellery, J; Tinti, E; Douxfils, J; Larondelle, Y; Mandiki, S N M; Kestemont, P

    2015-12-01

    This study was designated to investigate the effects of dietary fish oil (FO diet) replacement by linseed oil (LO diet) on regulation of immune response and disease resistance in Eurasian perch (Perca fluviatilis). A control diet containing fish oil (FO = cod liver oil) and characterized by high levels of n-3 high LC-PUFA (6% EPA, 7.5% of total fatty acids (FAs)) was compared to linseed oil diet (LO diet) composed of low LC-PUFA contents (1% EPA, 2.3% DHA of total FAs) but high C18 fatty acids levels. The experiment was conducted in quadruplicate groups of 80 fish each. After 10 weeks of feeding, the innate immune status was evaluated in various organs (liver, spleen, and head-kidney) (feeding condition). Two days later, a bacterial challenge was performed on fish from 2 rearing conditions: fish infected with Aeromonas salmonicida (bacteria condition) and fish injected with sterile medium but maintained in the same flow system that fish challenged with bacteria (sentinel condition). Three days after injection of bacteria, a significant decrease of lymphocyte, thrombocyte and basophil populations was observed while neutrophils were not affected. In addition, plasma lysozyme activity and reactive oxygen species production in kidney significantly increased in fish challenged with A. salmonicida while the plasma alternative complement pathway activity was not affected. Increase of plasma lysozyme activity as well as reactive oxygen species production in spleen and kidney of sentinel fish suggest that these immune defenses can also be activated, but at lower bacteria concentration than infected fish. No differences in leucocyte populations, plasma lysozyme and alternative complement pathway activities were observed between dietary treatments. Similarly, expression of genes related to eicosanoid synthesis in liver were not affected by the dietary oil source but were strongly stimulated in fish challenged with A. salmonicida. These findings demonstrated that the use of

  3. Enhanced Aeromonas salmonicida bacterin uptake and side effects caused by low frequency sonophoresis in rainbow trout (Oncorhynchus mykiss).

    PubMed

    Cobo, Cristóbal; Makosch, Katarzyna; Jung, Rainer; Kohlmann, Klaus; Knopf, Klaus

    2014-02-01

    Low frequency sonophoresis (LFS) has been recognized as one of the most advanced technologies in transdermal delivery of substances, due to the modification of the stratum corneum lipid bilayer, in focal skin applications in mammals. Based on these findings, LFS has been suggested as a potential technology to be used for enhancement in immersion fish vaccination. In contrast to mammals where LFS is applied to discrete regions of the skin, in fish the whole individual needs to be exposed for practical purposes. The current study evaluated the impact of LFS at 37 kHz on the uptake of an Aeromonas salmonicida bacterin and side effects of the treatment in rainbow trout. Quantitative real time PCR (qPCR) and immunohistochemistry were used to examine the bacterin uptake into skin and gill tissue. Side effects were assessed by behavioural examination, histology and blood serum analysis. The sonication intensity of 171 mW/cm² was enough for increasing skin permeability, but caused heavy erratic swimming and gill haemorrhages. Sonication intensities as low as 105 mW/cm² did not modify skin permeability and enhanced the bacterin uptake into the gill tissue by factor 15 compared to conventional immersion. Following sonication, the gill permeability for the bacterin decreased after 20 min and 120 min by factor 3 and 2, respectively. However, during sonication, erratic swimming of the fish raised some concerns. Further reduction of the sonication intensity to 57 mW/cm² did not induce erratic swimming, and the bacterin uptake into the gill tissue was still increased by factor 3. In addition, a decreasing albumin-globulin ratio in the serum of the rainbow trout within 40 min revealed that LFS leads to an inflammatory response. Consequently, based on both increased bacterin uptake and the inflammatory response, low intensity LFS has the potential to enhance vaccine immunity without significant side effects. PMID:24378683

  4. Aeromonas salmonicida Infection Only Moderately Regulates Expression of Factors Contributing to Toll-Like Receptor Signaling but Massively Activates the Cellular and Humoral Branches of Innate Immunity in Rainbow Trout (Oncorhynchus mykiss).

    PubMed

    Brietzke, Andreas; Korytář, Tomáš; Jaros, Joanna; Köllner, Bernd; Goldammer, Tom; Seyfert, Hans-Martin; Rebl, Alexander

    2015-01-01

    Toll-like receptors (TLRs) are known to detect a defined spectrum of microbial structures. However, the knowledge about the specificity of teleost Tlr factors for distinct pathogens is limited so far. We measured baseline expression profiles of 18 tlr genes and associated signaling factors in four immune-relevant tissues of rainbow trout Oncorhynchus mykiss. Intraperitoneal injection of a lethal dose of Aeromonas salmonicida subsp. salmonicida induced highly increased levels of cytokine mRNAs during a 72-hour postinfection (hpi) period. In contrast, only the fish-specific tlr22a2 and the downstream factor irak1 featured clearly increased transcript levels, while the mRNA concentrations of many other tlr genes decreased. Flow cytometry quantified cell trafficking after infection indicating a dramatic influx of myeloid cells into the peritoneum and a belated low level immigration of lymphoid cells. T and B lymphocytes were differentiated with RT-qPCR revealing that B lymphocytes emigrated from and T lymphocytes immigrated into head kidney. In conclusion, no specific TLR can be singled out as a dominant receptor for A. salmonicida. The recruitment of cellular factors of innate immunity rather than induced expression of pathogen receptors is hence of key importance for mounting a first immune defense against invading A. salmonicida. PMID:26266270

  5. Characterization of susceptibility and carrier status of burbot, Lota lota (L.), to IHNV, IPNV, Flavobacterium psychrophilum, Aeromonas salmonicida and Renibacterium salmoninarum.

    PubMed

    Polinski, M P; Fehringer, T R; Johnson, K A; Snekvik, K R; Lapatra, S E; Lafrentz, B R; Ireland, S C; Cain, K D

    2010-07-01

    In this study, susceptibility and potential carrier status of burbot, Lota lota, were assessed for five important fish pathogens. Burbot demonstrated susceptibility and elevated mortality following challenge with infectious haematopoietic necrosis virus (IHNV) by immersion and to Aeromonas salmonicida by intraperitoneal (i.p.) injection. IHNV persisted in fish for at least 28 days, whereas A. salmonicida was not re-isolated beyond 17 days post-challenge. In contrast, burbot appeared refractory to Flavobacterium psychrophilum following intramuscular (i.m.) injection and to infectious pancreatic necrosis virus (IPNV) by immersion. However, i.p injection of IPNV resulted in re-isolation of virus from fish for the duration of the 28 day challenge. Renibacterium salmoninarum appeared to induce an asymptomatic carrier state in burbot following i.p. injection, but overt manifestation of disease was not apparent. Viable bacteria persisted in fish for at least 41 days, and bacterial DNA isolated by diagnostic polymerase chain reaction was detected from burbot kidney tissue 90 days after initial exposure. This study is the first to investigate susceptibility of burbot to selected fish pathogens, and this information will aid in efforts to culture and manage this species. PMID:20367740

  6. Endogenous mutagenesis by an insertion sequence element identifies Aeromonas salmonicida AbcA as an ATP-binding cassette transport protein required for biogenesis of smooth lipopolysaccharide.

    PubMed Central

    Chu, S; Noonan, B; Cavaignac, S; Trust, T J

    1995-01-01

    Analysis of an Aeromonas salmonicida A layer-deficient/O polysaccharide-deficient mutant carrying a Tn5 insertion in the structural gene for A protein (vapA) showed that the abcA gene immediately downstream of vapA had been interrupted by the endogenous insertion sequence element ISAS1. Immunoelectron microscopy showed that O polysaccharides did not accumulate at the inner membrane-cytoplasm interface of this mutant. abcA encodes an unusual protein; it carries both an amino-terminal ATP-binding cassette (ABC) domain showing high sequence similarity to ABC proteins implicated in the transport of certain capsular and O polysaccharides and a carboxyl-terminal potential DNA-binding domain, which distinguishes AbcA from other polysaccharide transport proteins in structural and evolutionary terms. The smooth lipopolysaccharide phenotype was restored by complementation with abcA but not by abcA carrying site-directed mutations in the sequence encoding the ATP-binding site of the protein. The genetic organization of the A. salmonicida ABC polysaccharide system differs from other bacteria. abcA also differs in apparently being required for both O-polysaccharide synthesis and in energizing the transport of O polysaccharides to the cell surface. Images Fig. 2 Fig. 3 Fig. 4 PMID:7777581

  7. Efficacy of an extract from garlic, Allium sativum, against infection with the furunculosis bacterium, Aeromonas salmonicida, in rainbow trout, Oncorhynchus mykiss

    USGS Publications Warehouse

    Breyer, Kate E.; Getchell, Rodman G.; Cornwell, Emily R.; Wooster, Gregory A.; Ketola, H. George; Bowser, Paul R.

    2015-01-01

    Juvenile rainbow trout, Oncorhynchus mykiss, were fed diets containing 0, 0.5, 1.0, and 2.0% of a garlic extract, challenged with a modified 50% lethal dose of Aeromonas salmonicida and monitored for 28 d. There were significant increases in survival of trout fed 0.5 and 1.0% garlic extract as compared to the control and 2.0% garlic extract groups. A target animal safety study was performed at varying increments using the target dose of 0.5% garlic extract at 0× (0% garlic extract), 1× (0.5% garlic extract), 3× (1.5% garlic extract), and 5× (2.5% garlic extract) for 3× (6 wk) the duration of the original study. There was a significant increase in the level of circulating lymphocytes and a significant decrease in the level of circulating monocytes. The latter correlated to an increased level of pigment-containing macrophage centers within the renal tissue as garlic extract dosing increased, denoting a potential deleterious inflammatory effect as macrophage infiltration became severe at the highest dose. These studies suggest that feeding low-dose (0.5% or 1.0%) garlic extract improves survivability in rainbow trout when challenged with A. salmonicida and appears safe; however, higher levels do not appear to be effective and may cause deleterious effects on health.

  8. A comparison of the distribution of extracellular proteins produced by the protease-secreting organism Aeromonas salmonicida during aerobic and anaerobic growth.

    PubMed

    Fyfe, L; Coleman, G; Munro, A L

    1986-01-01

    Aeromonas salmonicida was grown aerobically and anaerobically in supplemented 3% (w/v) tryptone soya broth medium for 24 h at 25 degrees C. Although the bacterial density achieved was 4.9 times higher in the aerobic culture, the exoprotein produced per unit of bacterial dry weight was only 1.9 times higher than in the anaerobic culture. However, the protease activity of the exoprotein showed a marked reduction anaerobically, being only one-tenth of that of the exoprotein produced aerobically. This finding was consistent with the differing SDS-PAGE patterns of the extracellular proteins from the two cultures, which also showed marked loss and reinforcement of other, as yet unidentified extracellular products. PMID:3322167

  9. Dietary β-glucan stimulate complement and C-reactive protein acute phase responses in common carp (Cyprinus carpio) during an Aeromonas salmonicida infection.

    PubMed

    Pionnier, Nicolas; Falco, Alberto; Miest, Joanna; Frost, Patrick; Irnazarow, Ilgiz; Shrive, Annette; Hoole, Dave

    2013-03-01

    The effect of β-glucans as feed additive on the profile of C-reactive protein (CRP) and complement acute phase responses was studied in common carp Cyprinus carpio after exposition to a bacterial infection with Aeromonas salmonicida. Carp were orally administered with β-glucan (MacroGard®) for 14 days with a daily β-glucan intake of 6 mg per kg body weight. Fish were then intraperitoneally injected with either PBS or 1 × 10⁸ bacteria per fish and sampled at time 0, 6, 12, 24, 48, 72, 96 and 120 h post-injection (p.i.) for serum and head kidney, liver and mid-gut tissues. CRP levels and complement activity were determined in the serum samples whilst the gene expression profiles of CRP and complement related genes (crp1, crp2, c1r/s, bf/c2, c3 and masp2) were analysed in the tissues by quantitative PCR. Results obtained showed that oral administration of β-glucan for 14 days significantly increased serum CRP levels up to 2 fold and serum alternative complement activity (ACP) up to 35 fold. The bacterial infection on its own (i.e. not combined with a β-glucan feeding) did have significant effects on complement response whilst CRP was not detectably induced during the carp acute phase reaction. However, the combination of the infection and the β-glucan feeding did show significant effects on both CRP and complement profiles with higher serum CRP levels and serum ACP activity in the β-glucan fed fish than in the control fed fish. In addition, a distinct organ and time dependent expression profile pattern was detected for all the selected genes: a peak of gene expression first occurred in the head kidney tissue (6 h p.i. or 12 h p.i.), then an up-regulation in the liver several hours later (24 h p.i.) and finally up- or down-regulations in the mid-gut at 24 h p.i. and 72 h p.i. In conclusion, the results of this study suggest that MacroGard® stimulated CRP and complement responses to A. salmonicida infection in common carp. PMID:23291104

  10. Lipopolysaccharides isolated from Aeromonas salmonicida and Vibrio anguillarum show quantitative but not qualitative differences in inflammatory outcome in Sparus aurata (Gilthead seabream).

    PubMed

    Boltaña, S; Tridico, R; Teles, M; Mackenzie, S; Tort, L

    2014-08-01

    In fish, the defence system recognises pathogenic microorganisms via pathogen recognition receptors (PRRs) that sense particular structures of the pathogens; the so-called pathogen associated molecular patterns (PAMPs) such as bacterial lipopolysaccharides (LPSs). The result of the PAMP-PRR interactions leads to complex and orchestrated immune responses. In this study, Sparus aurata (Gilthead seabream) were intraperitoneally injected with purified lipopolysaccharide (LPS) from Aeromonas salmonicida (As)- and Vibrio anguillarum (Va) (1 mg*Kgfish(-1)), both Gram negative bacteria responsible for vibriosis and furunculosis respectively, therefore causing an impact upon marine fish cultures. Head-kidney, intestine, spleen, liver and blood samples were collected at 3, 6, 12 and 24 h post-injection. Plasma levels of cortisol, prostaglandins and lactate were measured and were significantly increased after As-LPS and Va-LPS treatment. Furthermore, tissue-specific differences of the gene regulatory patterns were evident for each LPS. When monocyte/macrophage cell cultures were challenged with As-LPS and Va-LPS, the pro-inflammatory cytokine mRNA abundances present a similar pattern of response. However, As-LPS always triggered a stronger response concerning TNFα, IL1β and cyclooxygenase-2 (COX2) mRNA abundance as well as PGE2 levels in the supernatant. Overall, the results indicate that specific LPSs do not activate different pro-inflammatory responses and that the observed gene expression pattern is tissue and concentration dependent. PMID:24954838

  11. Steelhead trout Oncorhynchus mykiss metabolic rate is affected by dietary Aloe vera inclusion but not by mounting an immune response against formalin-killed Aeromonas salmonicida.

    PubMed

    Zanuzzo, F S; Urbinati, E C; Nash, G W; Gamperl, A K

    2015-07-01

    The oxygen consumption (MO2) of two groups of 10° C acclimated steelhead trout Oncorhynchus mykiss was measured for 72 h after they were given a 100 µl kg(-1) intraperitoneal injection of formalin-killed Aeromonas salmonicida (ASAL) or phosphate-buffered saline (PBS). In addition, plasma cortisol levels were measured in fish from both groups prior to, and 1 and 3 h after, they were given a 30 s net stress. The first group was fed an unaltered commercial diet for 4 weeks, whereas the second group was fed the same diet but with 0·5% (5 g kg(-1) ) Aloe vera powder added; A. vera has potential as an immunostimulant for use in aquaculture, but its effects on basal and acute phase response (APR)-related metabolic expenditures and stress physiology, are unknown. Injection of ASAL v. PBS had no measurable effect on the MO2 of O. mykiss indicating that the APR in this species is not associated with any net increase in energy expenditure. In contrast, incorporating 0·5% A. vera powder into the feed decreased routine metabolic rate by c. 8% in both injection groups and standard metabolic rate in the ASAL-injected group (by c. 4 mg O2 kg(-1) h(-1) ; 5%). Aloe vera fed fish had resting cortisol levels that were approximately half of those in fish on the commercial diet (c. 2·5 v. 5·0 ng ml(-1) ), but neither this difference nor those post-stress reached statistical significance (P > 0·05). PMID:26010230

  12. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1997-01-01

    Logarithmic strain is the preferred measure of strain used by materials scientists, who typically refer to it as the "true strain." It was Nadai who gave it the name "natural strain," which seems more appropriate. This strain measure was proposed by Ludwik for the one-dimensional extension of a rod with length l. It was defined via the integral of dl/l to which Ludwik gave the name "effective specific strain." Today, it is after Hencky, who extended Ludwik's measure to three-dimensional analysis by defining logarithmic strains for the three principal directions.

  13. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1995-01-01

    The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.

  14. Strain Gage

    NASA Technical Reports Server (NTRS)

    1995-01-01

    HITEC Corporation developed a strain gage application for DanteII, a mobile robot developed for NASA. The gage measured bending forces on the robot's legs and warned human controllers when acceptable forces were exceeded. HITEC further developed the technology for strain gage services in creating transducers out of "Indy" racing car suspension pushrods, NASCAR suspension components and components used in motion control.

  15. Hip flexor strain - aftercare

    MedlinePlus

    Pulled hip flexor - aftercare; Hip flexor injury - aftercare; Hip flexor tear - aftercare; Iliopsoas strain - aftercare; Strained iliopsoas muscle - aftercare; Torn iliopsoas muscle - aftercare; Psoas strain - aftercare

  16. High temperature strain gage apparent strain compensation

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K.; Moore, T. C., Sr.

    1992-01-01

    Once an installed strain gage is connected to a strain indicating device and the instrument is balanced, a subsequent change in temperature of the gage installation will generally produce a resistance change in the gage. This purely temperature-induced resistance will be registered by the indicating device as a strain and is referred to as 'apparent strain' to distinguish it from strain due to applied stress. One desirable technique for apparent strain compensation is to employ two identical gages with identical mounting procedures which are connected with a 'half bridge' configuration where gages see the same thermal environment but only one experiences a mechanical strain input. Their connection in adjacent arms of the bridge will then balance the thermally induced apparent strains and, in principle, only the mechanical strain remains. Two approaches that implement this technique are discussed.

  17. Geobacteraceae strains and methods

    DOEpatents

    Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana

    2015-07-07

    Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

  18. Muscle strain (image)

    MedlinePlus

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  19. Muscle strain treatment

    MedlinePlus

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  20. Strains and Sprains

    MedlinePlus

    ... Children's Sports Injuries Computer-Related Repetitive Stress Injuries Knee Injuries Broken Bones, Sprains, and Strains Strains and Sprains ... Pain Going to a Physical Therapist Hamstring Strain Knee Injuries Sports and Exercise Safety Dealing With Sports Injuries ...

  1. Prevalence, characterization, and antimicrobial resistance of Aeromonas strains from various retail food products in Mumbai, India.

    PubMed

    Nagar, Vandan; Shashidhar, Ravindranath; Bandekar, Jayant R

    2011-09-01

    A total of 154 food samples (chicken, fish, and ready-to-eat sprouts) from various retail outlets in Mumbai, India, were analyzed for the presence of Aeromonas spp. over a period of 2 y (January 2006 to March 2008). Twenty-two Aeromonas isolates belonging to 7 different species were isolated from 18 (11.7%) food samples. The highest percentages of isolation were from chicken (28.6%) followed by fish (20%) and sprout (2.5%) samples. Aeromonas caviae, A. veronii bv. sobria, and A. salmonicida were the most frequently isolated species from sprouts, chicken, and fish samples, respectively. The genes encoding for putative virulence factors, cytotoxic enterotoxin (act), hemolysin (hly), aerolysin (aer), elastase (ahyB), and lipase (lip) were detected using polymerase chain reaction method in 59.1%, 40.9%, 22.7%, 54.5%, and 31.8% of the strains, respectively. The isolated Aeromonas strains were found to be positive for virulence factors, that is, amylase, DNase, gelatinase, protease, and lipase production. More than 60% isolates were also positive for β-hemolytic activity. All these food isolates were found to be resistant to ampicillin and bacitracin, and sensitive to gentamicin, 3rd-generation cephalosporins (ceftazidime, cephotaxime, ceftriaxone), and chloramphenicol. Seventeen (77.2%) isolates harbored single and/or multiple plasmids (approximately 5 to >16 kb). The XbaI digestion patterns of chromosomal DNA of these isolates, using pulsed field gel electrophoresis, showed high genetic diversity among these isolates. Our results demonstrate the presence of various Aeromonas spp. with virulence potential and antimicrobial resistance in different food products marketed in Mumbai, India. The potential health risks posed by consumption of these raw or undercooked food products should not be underestimated. PMID:21824136

  2. Improving survival and storage stability of bacteria recalcitrant to freeze-drying: a coordinated study by European culture collections.

    PubMed

    Peiren, Jindrich; Buyse, Joke; De Vos, Paul; Lang, Elke; Clermont, Dominique; Hamon, Sylviane; Bégaud, Evelyne; Bizet, Chantal; Pascual, Javier; Ruvira, María A; Macián, M Carmen; Arahal, David R

    2015-04-01

    The objective of this study is to improve the viability after freeze-drying and during storage of delicate or recalcitrant strains safeguarded at biological resource centers. To achieve this objective, a joint experimental strategy was established among the different involved partner collections of the EMbaRC project ( www.embarc.eu ). Five bacterial strains considered as recalcitrant to freeze-drying were subjected to a standardized freeze-drying protocol and to seven agreed protocol variants. Viability of these strains was determined before and after freeze-drying (within 1 week, after 6 and 12 months, and after accelerated storage) for each of the protocols. Furthermore, strains were exchanged between partners to perform experiments with different freeze-dryer-dependent parameters. Of all tested variables, choice of the lyoprotectant had the biggest impact on viability after freeze-drying and during storage. For nearly all tested strains, skim milk as lyoprotectant resulted in lowest viability after freeze-drying and storage. On the other hand, best freeze-drying and storage conditions were strain and device dependent. For Aeromonas salmonicida CECT 894(T), best survival was obtained when horse serum supplemented with trehalose was used as lyoprotectant, while Aliivibrio fischeri LMG 4414(T) should be freeze-dried in skim milk supplemented with marine broth in a 1:1 ratio. Freeze-drying Campylobacter fetus CIP 53.96(T) using skim milk supplemented with trehalose as lyoprotectant resulted in best recovery. Xanthomonas fragariae DSM 3587(T) expressed high viability after freeze-drying and storage for all tested lyoprotectants and could not be considered as recalcitrant. In contrary, Flavobacterium columnare LMG 10406(T) did not survive the freeze-drying process under all tested conditions. PMID:25773973

  3. Program Calibrates Strain Gauges

    NASA Technical Reports Server (NTRS)

    Okazaki, Gary D.

    1991-01-01

    Program dramatically reduces personnel and time requirements for acceptance tests of hardware. Data-acquisition system reads output from Wheatstone full-bridge strain-gauge circuit and calculates strain by use of shunt calibration technique. Program nearly instantaneously tabulates and plots strain data against load-cell outputs. Modified to acquire strain data for other specimens wherever full-bridge strain-gauge circuits used. Written in HP BASIC.

  4. Superlattice strain gage

    DOEpatents

    Noel, Bruce W.; Smith, Darryl L.; Sinha, Dipen N.

    1990-01-01

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element.

  5. Superlattice strain gage

    DOEpatents

    Noel, B.W.; Smith, D.L.; Sinha, D.N.

    1988-06-28

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element. 8 figs.

  6. Miniature biaxial strain transducer

    NASA Technical Reports Server (NTRS)

    Hoffman, I. S. (Inventor)

    1976-01-01

    A reusable miniature strain transducer for use in the measurement of static or quasi-static, high level, biaxial strain on the surface of test specimens or structures was studied. Two cantilever arms, constructed by machining the material to appropriate flexibility, are self-aligning and constitute the transducing elements of the device. Used in conjunction with strain gages, the device enables testing beyond normal gage limits for high strains and number of load cycles. The device does not require conversion computations since the electrical output of the strain gages is directly proportional to the strain measured.

  7. Sprains and Strains

    MedlinePlus

    ... happens. A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can ... suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing ...

  8. Strains and Sprains

    MedlinePlus

    ... move the injured part, and you might even think you have broken a bone. How Does a Strain or Sprain Happen? Strains often happen when you put a lot of pressure on a muscle or you push it too far, such as when lifting a heavy object. Strains may be more likely to happen if ...

  9. Can strain magnetize light?

    NASA Astrophysics Data System (ADS)

    2013-02-01

    Strain in photonic structures can induce pseudomagnetic fields and Landau levels. Nature Photonics spoke to Mordechai Segev, Mikael Rechtsman, Alexander Szameit and Julia Zeuner about their unique approach.

  10. Elevated temperature strain gages

    NASA Technical Reports Server (NTRS)

    Brittain, J. O.; Geslin, D.; Lei, J. F.

    1986-01-01

    One of the goals of the HOST Program is the development of electrical resistance strain gages for static strain measurements at temperatures equal to or greater than 1273 K. Strain gage materials must have a reproducible or predictable response to temperature, time and strain. It is the objective of this research to investigate criteria for the selection of materials for such applications through electrical properties studies. The results of the investigation of two groups of materials, refractory compounds and binary alloy solid solutions are presented.

  11. Thin film strain transducer

    NASA Technical Reports Server (NTRS)

    Rand, J. L. (Inventor)

    1984-01-01

    A strain transducer system and process for making the same is disclosed. A beryllium copper ring having four strain gages is electrically connected in Wheatstone bridge fashion to the output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of a ring which provides an electrical signal through the gages proportional to the surface strain. A photographic pattern of a one half ring segment as placed on a sheet of beryllium copper for chem-mill etch formation is illustrated.

  12. Geodetic Strain Analysis Tool

    NASA Technical Reports Server (NTRS)

    Kedar, Sharon; Baxter, Sean C.; Parker, Jay W.; Webb, Frank H.; Owen, Susan E.; Sibthorpe, Anthony J.; Dong, Danan

    2011-01-01

    A geodetic software analysis tool enables the user to analyze 2D crustal strain from geodetic ground motion, and create models of crustal deformation using a graphical interface. Users can use any geodetic measurements of ground motion and derive the 2D crustal strain interactively. This software also provides a forward-modeling tool that calculates a geodetic velocity and strain field for a given fault model, and lets the user compare the modeled strain field with the strain field obtained from the user s data. Users may change parameters on-the-fly and obtain a real-time recalculation of the resulting strain field. Four data products are computed: maximum shear, dilatation, shear angle, and principal components. The current view and data dependencies are processed first. The remaining data products and views are then computed in a round-robin fashion to anticipate view changes. When an analysis or display parameter is changed, the affected data products and views are invalidated and progressively re-displayed as available. This software is designed to facilitate the derivation of the strain fields from the GPS and strain meter data that sample it to facilitate the understanding of the strengths and weaknesses of the strain field derivation from continuous GPS (CGPS) and other geodetic data from a variety of tectonic settings, to converge on the "best practices" strain derivation strategy for the Solid Earth Science ESDR System (SESES) project given the CGPS station distribution in the western U.S., and to provide SESES users with a scientific and educational tool to explore the strain field on their own with user-defined parameters.

  13. Mechanical strain isolator mount

    NASA Technical Reports Server (NTRS)

    James, Gordon E. (Inventor)

    1991-01-01

    Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument.

  14. Light intensity strain analysis

    NASA Technical Reports Server (NTRS)

    Williams, J. G. (Inventor)

    1973-01-01

    A process is described for the analysis of the strain field of structures subjected to large deformations involving a low modulus substrate having a high modulus, relatively thin coating. The optical properties of transmittance and reflectance are measured for the coated substrate while stressed and unstressed to indicate the strain field for the coated substrate.

  15. Strain gauge installation tool

    DOEpatents

    Conard, Lisa Marie

    1998-01-01

    A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  16. Mechanochromic polyurethane strain sensor

    NASA Astrophysics Data System (ADS)

    Cellini, F.; Khapli, S.; Peterson, S. D.; Porfiri, M.

    2014-08-01

    In this Letter, we study the mechanical and optical response of a thermoplastic polyurethane blended with 0.5 wt. % of bis(benzoxazolyl)stilbene dye. The mechanochromic behavior of the material is characterized in a uniaxial stress-relaxation test by simultaneously acquiring the applied force, mechanical deformation, and fluorescence emission. To offer insight into the stress-strain response of the polymer-dye blend, we adapt a classical nonlinear constitutive behavior for elastomeric materials that accounts for stress-induced softening. We correlate the fluorescent response with the mechanical strain to demonstrate the possibility of accurate strain sensing for a broad range of deformations during both loading and unloading.

  17. Strain gauge installation tool

    SciTech Connect

    Conard, Lisa Marie

    1997-12-01

    A tool and a method for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  18. What Are Sprains and Strains?

    MedlinePlus

    ... sprain, one or more ligaments is stretched or torn. What Causes a Sprain? Where Do Sprains Usually ... strain, a muscle or tendon is stretched or torn. What Causes Strains? A strain is caused by ...

  19. Nanowires enabling strained photovoltaics

    SciTech Connect

    Greil, J.; Bertagnolli, E.; Lugstein, A.; Birner, S.

    2014-04-21

    Photovoltaic nano-devices have largely been relying on charge separation in conventional p-n junctions. Junction formation via doping, however, imposes major challenges in process control. Here, we report on a concept for photovoltaic energy conversion at the nano scale without the need for intentional doping. Our approach relies on charge carrier separation in inhomogeneously strained germanium nanowires (Ge NWs). This concept utilizes the strain-induced gradient in bandgap along tapered NWs. Experimental data confirms the feasibility of strain-induced charge separation in individual vapor-liquid-solid grown Ge NW devices with an internal quantum efficiency of ∼5%. The charge separation mechanism, though, is not inherently limited to a distinct material. Our work establishes a class of photovoltaic nano-devices with its opto-electronic properties engineered by size, shape, and applied strain.

  20. Sprains and Strains

    MedlinePlus

    ... people at risk for strains. Gymnastics, tennis, rowing, golf, and other sports that require extensive gripping can ... Trials and You was designed to help people learn more about clinical trials, why they matter, and ...

  1. MEMS Graphene Strain Sensor

    NASA Astrophysics Data System (ADS)

    Young, Clinton Wen-Chieh

    Graphene is a two dimensional honeycomb structure of sp2 hybridized carbon atoms that has possibilities in many applications due to its excellent mechanical and electrical properties. One application for Graphene is in the field of sensors. Graphene's electronic properties do not degrade when it undergoes mechanical strain which is advantageous for strain sensors. In this thesis, certain properties, such as the piezo-resistivity and flexibility, of graphene will be explored to show how they can be utilized to make a strain sensing device. Our original fabrication process of patterning graphene and the transfer process of graphene onto a flexible substrate will be discussed. The development of a stretchable and flexible graphene based rosette strain sensor will also be detailed. Developing a novel, reliable patterning process for the graphene is the first step to manufacture a stretchable graphene based sensor. The graphene was patterned using a photolithography and etching process that was developed by our research team, then it was transferred to a flexible polymer substrate with the use of a combination of soft lithography and wet etching of the Ni foil with ferric chloride solution. Graphene patterning is an essential step in fabricating reliable and sensitive sensors. With this process, graphene can be consistently patterned into different shapes and sizes. To utilize the graphene as the sensing material it also needs to be transferred onto a flexible substrate. The innovative transfer process developed by our research team consistently adheres graphene to a flexible PDMS substrate while removing the original nickel substrate. In the end, the graphene was transferred from the metal substrate to the desired flexible substrate. This process was repeated multiple times to create a stack and multilayer device. While many graphene-based strain sensors have been developed, they are uni-directional and can only measure the strain applied on the sensor in a principle

  2. Annihilation of strained vortices

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshifumi

    2014-11-01

    As an initial stage of vortex reconnection, approach of nearly anti-parallel vortices has often been observed experimentally and studied numerically. Inspired by the recent experiment by Kleckner and Irvine on the dynamics of knotted vortices, we have studied the motion of two anti-parellel Burgers vortices driven by an axisymmetric linear straining field. We first extend the Burgers vortex solution which is a steady exact solution of the Navier-Stokes equation to a time-dependent exact solution. Then by superposing two such solutions, we investigate the annihilation process analytically. We can demonstrate that during the annihilation process the total vorticity decays exponentially on a time-scale proportional to the inverse of the rate of strain, even as the kinematic viscosity tends to 0. The analytic results are compared with the numerical simulations of two strained vortices with the vortex-vortex nonlinear interaction by Buntine and Pullin.

  3. The atomic strain tensor

    SciTech Connect

    Mott, P.H.; Argon, A.S. ); Suter, U.W. Massachusetts Institute of Technology, Cambridge, MA )

    1992-07-01

    A definition of the local atomic strain increments in three dimensions and an algorithm for computing them is presented. An arbitrary arrangement of atoms is tessellated in to Delaunay tetrahedra, identifying interstices, and Voronoi polyhedra, identifying atomic domains. The deformation gradient increment tensor for interstitial space is obtained from the displacement increments of the corner atoms of Delaunay tetrahedra. The atomic site strain increment tensor is then obtained by finding the intersection of the Delaunay tetrahedra with the Voronoi polyhedra, accumulating the individual deformation gradient contributions of the intersected Delaunay tetrahedra into the Voronoi polyhedra. An example application is discussed, showing how the atomic strain clarifies the relative local atomic movement for a polymeric glass treated at the atomic level. 6 refs. 10 figs.

  4. Strain isolated ceramic coatings

    NASA Technical Reports Server (NTRS)

    Tolokan, R. P.; Brady, J. B.; Jarrabet, G. P.

    1985-01-01

    Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

  5. Diffusion on strained surfaces

    NASA Astrophysics Data System (ADS)

    Schroeder, M.; Wolf, D. E.

    1997-03-01

    The change of diffusion kinetics when elastic fields are present is discussed for diffusion on (001) surfaces of simple cubic, fcc and bcc lattices. All particles interact pairwise with a Lennard-Jones potential. The simple cubic lattice was stabilized by an anisotropic prefactor. It is found that generically compressive strain enhances diffusion whereas tensile strain increases the activation barrier. An approximately linear dependence of the barrier in a wide range of misfits is found. In heteroepitaxy, diffusion on top of large clusters is inhomogeneous and anisotropic. The kinetics close to edges and centers of islands are remarkably different. In many cases changes of binding energies are small compared to those of saddle point energies. Thermodynamic arguments (minimization of free energy) are not appropriate to describe diffusion on strained surfaces in these cases.

  6. Strain gauge installation tool

    DOEpatents

    Conard, L.M.

    1998-06-16

    A tool and a method are disclosed for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool. 6 figs.

  7. ConStrains identifies microbial strains in metagenomic datasets

    PubMed Central

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk

    2015-01-01

    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived data sets provides insights into microbial community dynamics. PMID:26344404

  8. Local Strain Evaluation of Strained-SOI Structures

    NASA Astrophysics Data System (ADS)

    Usuda, Koji; Mizuno, Tomohisa; Numata, Toshinori; Tezuka, Tsutomu; Sugiyama, Naoharu; Moriyama, Yoshihiko; Nakaharai, Shu; Takagi, Shin-Ichi

    The strain relaxation within a strained-Si on SiGe on insulator (SGOI) structure might be one of the key issues in development of strained-Si MOSFET devices for high-performance ULSIs. In order to investigate the strain relaxation within the thin strained-Si layers, a new characterization technique to directly evaluate a local strain variation in the layers is required. Hence, we have developed the nano-beam electron diffraction (NBD) method which has a lateral resolution of 10 nm and a strain resolution of 0.1%. In this paper, we discuss a detailed investigation of whether the NBD method could be utilized to clarify a strain in a strained-Si layer on the SGOI structures.

  9. ConStrains identifies microbial strains in metagenomic datasets.

    PubMed

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk

    2015-10-01

    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived datasets provides insights into microbial community dynamics. PMID:26344404

  10. The strained state cosmology

    NASA Astrophysics Data System (ADS)

    Tartaglia, Angelo

    2016-01-01

    Starting from some relevant facts concerning the behavior of the universe over large scale and time span, the analogy between the geometric approach of General Relativity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time reproduces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theories. The possible role of structure topological defects is also mentioned. The conclusion is that SSC is at least as good as the ΛCDM standard cosmology, giving a more intuitive interpretation of the physical nature of the phenomena.

  11. Strain gage barometric transmitter

    NASA Technical Reports Server (NTRS)

    Viton, P.

    1977-01-01

    A strain gage barometric transmitter for measuring the atmospheric pressure in severe environmental conditions is described. This equipment specifications are presented and its performance assessed. It is shown that this barometric sensor can measure the atmospheric pressure with a precision of 0.5 mb during a 6 month period.

  12. Accurate strain measurements in highly strained Ge microbridges

    NASA Astrophysics Data System (ADS)

    Gassenq, A.; Tardif, S.; Guilloy, K.; Osvaldo Dias, G.; Pauc, N.; Duchemin, I.; Rouchon, D.; Hartmann, J.-M.; Widiez, J.; Escalante, J.; Niquet, Y.-M.; Geiger, R.; Zabel, T.; Sigg, H.; Faist, J.; Chelnokov, A.; Rieutord, F.; Reboud, V.; Calvo, V.

    2016-06-01

    Ge under high strain is predicted to become a direct bandgap semiconductor. Very large deformations can be introduced using microbridge devices. However, at the microscale, strain values are commonly deduced from Raman spectroscopy using empirical linear models only established up to ɛ100 = 1.2% for uniaxial stress. In this work, we calibrate the Raman-strain relation at higher strain using synchrotron based microdiffraction. The Ge microbridges show unprecedented high tensile strain up to 4.9% corresponding to an unexpected Δω = 9.9 cm-1 Raman shift. We demonstrate experimentally and theoretically that the Raman strain relation is not linear and we provide a more accurate expression.

  13. The meaning of role strain.

    PubMed

    Ward, C R

    1986-01-01

    Explicating the meaning of the concept of role strain is important in role theory formulation, an area requiring further development to provide explanations and predictions for both patient and provider roles. In this analysis, the use of the term role strain is traced from the structural-functionalist and symbolic-interactionist perspectives. Descriptive, stipulative, and connotative definitions of role strain are derived, and necessary and relevant properties are proposed. Antecedent and intervening conditions for role strain are outlined from the literature. Role strain manifestations and empirical referents are presented, and an initial step is taken toward a theoretical formulation by defining role strain within the context of role stress. PMID:3079985

  14. Highly stretchable miniature strain sensor for large dynamic strain measurement

    DOE PAGESBeta

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

  15. Highly stretchable miniature strain sensor for large dynamic strain measurement

    SciTech Connect

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages, as its gauge factor is 500 times of that of the conventional foil strain gages.

  16. Isolation of a pigment-producing strain of Aeromonas liquefaciens from silver salmon (Oncorhynchus kisutch)

    USGS Publications Warehouse

    Ross, A.J.

    1962-01-01

    Aeromonas salmonicida, the etiological agent of furunculosis in fish, is distinctive in the field of fish diseases in that it may readily be recognized by the water-soluble reddish-brown pigment formed on culture media containing tyrosine. Additional tests for the identification of this organism include blackening of the colonial growth when flooded with an aqueous solution of p-phenylenediamine and a lack of motility (Griffin, Progressive Fish Culturist 14:74, 1952).

  17. High temperature strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); You, Tao (Inventor)

    2011-01-01

    A ceramic strain gage based on reactively sputtered indium-tin-oxide (ITO) thin films is used to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500.degree. C. A scanning electron microscopy (SEM) of the thick ITO sensors reveals a partially sintered microstructure comprising a contiguous network of submicron ITO particles with well defined necks and isolated nanoporosity. Densification of the ITO particles was retarded during high temperature exposure with nitrogen thus stabilizing the nanoporosity. ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established.

  18. Novel strained superjunction VDMOS

    NASA Astrophysics Data System (ADS)

    Naugarhiya, Alok; Dubey, Shashank; Kondekar, Pravin N.

    2015-09-01

    In this paper, we have proposed novel strained superjunction (s-SJ) vertical double diffused MOS (VDMOS). Through channel engineering, we have introduced strain effects in s-SJ device using thin separate p-type silicon-germanium (p-SiGe) layer over silicon p-pillar. Further, we have designed process flow for the possible fabrication of s-SJ VDMOS. The proposed s-SJ devices fitted with less input capacitance (Cin) and 1.2∼3 times higher output current density than conventional SJ VDMOS. Therefore, 40% less gate charge (Qg) is required to turn-on the s-SJ VDMOS and Ron A is optimized in between 12% and 46%.

  19. Strain Release Amination

    PubMed Central

    Gianatassio, Ryan; Lopchuk, Justin M.; Wang, Jie; Pan, Chung-Mao; Malins, Lara R.; Prieto, Liher; Brandt, Thomas A.; Collins, Michael R.; Gallego, Gary M.; Sach, Neal W.; Spangler, Jillian E.; Zhu, Huichin; Zhu, Jinjiang; Baran, Phil S.

    2015-01-01

    To optimize drug candidates, modern medicinal chemists are increasingly turning to an unconventional structural motif: small, strained ring systems. However, the difficulty of introducing substituents such as bicyclo[1.1.1]pentanes, azetidines, or cyclobutanes often outweighs the challenge of synthesizing the parent scaffold itself. Thus, there is an urgent need for general methods to rapidly and directly append such groups onto core scaffolds. Here we report a general strategy to harness the embedded potential energy of effectively spring-loaded C–C and C–N bonds with the most oft-encountered nucleophiles in pharmaceutical chemistry, amines. Strain release amination can diversify a range of substrates with a multitude of desirable bioisosteres at both the early and late-stages of a synthesis. The technique has also been applied to peptide labeling and bioconjugation. PMID:26816372

  20. Interfacial residual thermal strain

    NASA Astrophysics Data System (ADS)

    Kasen, M.; Santoyo, R.

    A method has been developed for assessing the influence of polymer chemical composition and of processing parameters on the magnitude of residual stress developed in glass-fibre-reinforced composites subjected to various cure cycles and subsequently cooled to cryogenic temperatures. The test method was applied to nine resin types, including epoxy, vinyl ester, polyester, cyanate ester and phenolic formulations. Results suggest that polyester resin develops substantially less overall residual strain than do the other resin systems.

  1. Sports Hernia: Misdiagnosed Muscle Strain

    MedlinePlus

    ... Manipulative Treatment Becoming a DO Video Library Misdiagnosed Muscle Strain Can Be A Pain Page Content If ... speeds, sports hernias are frequently confused with common muscle strain ,” says Michael Sampson, DO, who practices in ...

  2. Genealogies of mouse inbred strains.

    PubMed

    Beck, J A; Lloyd, S; Hafezparast, M; Lennon-Pierce, M; Eppig, J T; Festing, M F; Fisher, E M

    2000-01-01

    The mouse is a prime organism of choice for modelling human disease. Over 450 inbred strains of mice have been described, providing a wealth of different genotypes and phenotypes for genetic and other studies. As new strains are generated and others become extinct, it is useful to review periodically what strains are available and how they are related to each other, particularly in the light of available DNA polymorphism data from microsatellite and other markers. We describe the origins and relationships of inbred mouse strains, 90 years after the generation of the first inbred strain. Given the large collection of inbred strains available, and that published information on these strains is incomplete, we propose that all genealogical and genetic data on inbred strains be submitted to a common electronic database to ensure this valuable information resource is preserved and used efficiently. PMID:10615122

  3. Construction of the Inbred Strain.

    PubMed

    Shinya, Minori

    2016-01-01

    Genetically homogeneous populations such as inbred strains are valuable experimental tools in various fields of biomedical analyses. In many animals, inbred strains are established by consecutive sib-pair mating for a minimum of 20 generations. As the generation proceeds, fitness of the population reduces usually. Therefore, in order to establish inbred strains, the important point is the selection of pairs in good condition at each generation. Here, I describe the procedure and tips for generating inbred strains in zebrafish. PMID:27464804

  4. Strain calibration of optical FBG-based strain sensors

    NASA Astrophysics Data System (ADS)

    Roths, Johannes; Wilfert, Andre; Kratzer, Peter; Jülich, Florian; Kuttler, Rolf

    2010-09-01

    A facility for strain sensitivity calibration of optical FBG-based strain sensors according to the German VDI/VDE 2660 guideline was established and characterized. Statistical analysis of several calibration measurement series performed with one single type of FBG strain sensor and application technique showed a reproducibility of 0.15%. Strain sensitivities for FBGs inscribed in two different types of optical fibres (GF1B and PR2008) showed significantly different strain sensitivities of k = 0.7885+/-0.0026 and k = 0.7758+/-0.0024, respectively.

  5. Strain balanced quantum posts

    SciTech Connect

    Alonso-Alvarez, D.; Alen, B.; Ripalda, J. M.; Llorens, J. M.; Taboada, A. G.; Briones, F.; Roldan, M. A.; Hernandez-Saz, J.; Hernandez-Maldonado, D.; Herrera, M.; Molina, S. I.

    2011-04-25

    Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here, we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.

  6. Strain actuated aeroelastic control

    NASA Technical Reports Server (NTRS)

    Lazarus, Kenneth B.

    1992-01-01

    Viewgraphs on strain actuated aeroelastic control are presented. Topics covered include: structural and aerodynamic modeling; control law design methodology; system block diagram; adaptive wing test article; bench-top experiments; bench-top disturbance rejection: open and closed loop response; bench-top disturbance rejection: state cost versus control cost; wind tunnel experiments; wind tunnel gust alleviation: open and closed loop response at 60 mph; wind tunnel gust alleviation: state cost versus control cost at 60 mph; wind tunnel command following: open and closed loop error at 60 mph; wind tunnel flutter suppression: open loop flutter speed; and wind tunnel flutter suppression: closed loop state cost curves.

  7. [Echinococcus and strain concepts].

    PubMed

    Utük, Armağan Erdem; Simsek, Sami

    2008-01-01

    Hydatid disease (echinococcosis) is one of the most important parasitic zoonoses and remains a public health and economic problem all over the world. Echinococcus granulosus includes a number of genetic variants and, up to date, analyses of mitochondrial DNA sequences have identified ten distinct genetic types (genotypes G1-10). This categorization follows closely the pattern of strain variation emerging based on biological characteristics. The extensive variation in E. granulosus may influence life-cycle patterns, host specificity, development rate, antigenicity, transmission dynamics, sensitivity to chemotherapeutic agents, and pathology. In this review, the recent genetic characterizations of Echinococcus genus have been summarized. PMID:18351549

  8. Compensated High Temperature Strain Gage

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A device for measuring strain in substrates at high temperatures in which the thermally induced apparent strain is nulled is described. Two gages are used, one active gage and one compensating gage. Both gages are placed on the substrate to be gaged; the active gage is attached such that it responds to mechanical and thermally induced apparent strain while the compensating gage is attached such that it does not respond to mechanical strain and and measures only thermally induced apparent strain. A thermal blanket is placed over the two gages to maintain the gages at the same temperature. The two gages are wired as adjacent arms of a wheatstone bridge which nulls the thermally induced apparent strain giving a true reading of the mechanical strain in the substrate.

  9. Geodetic strain measurements in Washington.

    USGS Publications Warehouse

    Savage, J.C.; Lisowski, M.; Prescott, W.H.

    1981-01-01

    Two new geodetic measurements of strain accumulation in the state of Washington for the interval 1972-1979 are reported. Near Seattle the average principal strain rates are 0.07 + or - 0.03 mu strain/yr N19oW and -0.13 + or - 0.02 mu strain/yr N71oE, and near Richland (south central Washington) the average principal strain rates are -0.02 + or - 0.01 mu strain/yr N36oW and -0.04 + or - 0.01 mu strain/yr N54oE. Extension is taken as positive, and the uncertainties quoted are standard deviations. A measurement of shear strain accumulation (dilation not determined) in the epoch 1914- 1966 along the north coast of Vancouver Island by the Geodetic Survey of Canada indicates a marginally significant accumulation of right-lateral shear (0.06 + or - 0.03 mu rad/yr) across the plate boundary (N40oW strike). Although there are significant differences in detail, these strain measurements are roughly consistent with a crude dislocation model that represents subduction of the Juan de Fuca plate. The observed accumulation of strain implies that large, shallow, thrust earthquakes should be expected off the coast of Washington and British Columbia. However, this conclusion is not easily reconciled with either observations of elevation change along the Washington coast or the focal mechanism solutions for shallow earthquakes in Washington. -Authors

  10. Inhomogeneous strains in small particles

    NASA Astrophysics Data System (ADS)

    Marks, L. D.

    1985-02-01

    This paper considers the evidence for strains in small particles. Firstly, the dynamical electron diffraction theory for dark field imaging of small particles is briefly reviewed, considering primarily the effects of strain on wedge crystals and identifying the fingerprint of strain contrast effects under strong beam conditions. Evidence included herein and from published papers by other authors clearly shows inhomogeneous strain effects in both multiply twinned particles and single crystals. Considering these results and earlier reports of lattice parameter changes, there are problems with the uniqueness of these analyses, and the strains in the small single crystals are thought more likely to be due to interfacial stresses or contaminants than any intrinsic particle effect; there are so many different origins of this type of strain that we cannot with confidence isolate a unique source. It is emphasised that the uniqueness of any interpretation of experimental results from small particles must be very carefully considered.

  11. Strain Engineering in Graphene

    NASA Astrophysics Data System (ADS)

    Castro Neto, Antonio

    2011-03-01

    Graphene is a unique example of a one atom thick metallic membrane. Hence, graphene brings together properties of soft and hard condensed matter systems. The elementary electronic excitations in graphene, the Dirac quasiparticles, couple in a singular way to structural distortions in the form of scalar and vector potentials. Therefore, graphene has an effective electrodynamics where structural deformations couple to the Dirac particles at equal footing to electric and magnetic fields. This so-called strain engineering of the electronic properties of graphene opens doors for a new paradigm in terms of electronic devices, where electronic properties can be manipulated at will using its membrane-like properties. I thank partial support from from DOE Grant DE-FG02-08ER46512 and ONR Grant MURI N00014-09-1-1063.

  12. Thermal strain imaging: a review

    PubMed Central

    Seo, Chi Hyung; Shi, Yan; Huang, Sheng-Wen; Kim, Kang; O'Donnell, Matthew

    2011-01-01

    Thermal strain imaging (TSI) or temporal strain imaging is an ultrasound application that exploits the temperature dependence of sound speed to create thermal (temporal) strain images. This article provides an overview of the field of TSI for biomedical applications that have appeared in the literature over the past several years. Basic theory in thermal strain is introduced. Two major energy sources appropriate for clinical applications are discussed. Promising biomedical applications are presented throughout the paper, including non-invasive thermometry and tissue characterization. We present some of the limitations and complications of the method. The paper concludes with a discussion of competing technologies. PMID:22866235

  13. Hydrogen production from microbial strains

    DOEpatents

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  14. Strain in silicon nanowire beams

    NASA Astrophysics Data System (ADS)

    Ureña, Ferran; Olsen, Sarah H.; Šiller, Lidija; Bhaskar, Umesh; Pardoen, Thomas; Raskin, Jean-Pierre

    2012-12-01

    In this work, strain in silicon free standing beams loaded in uniaxial tension is experimentally and theoretically investigated for strain values ranging from 0 to 3.6%. The fabrication method allows multiple geometries (and thus strain values) to be processed simultaneously on the same wafer while being studied independently. An excellent agreement of strain determined by two non-destructive characterization techniques, Raman spectroscopy and mechanical displacement using scanning electron microscopy (SEM) markers, is found for all the sample lengths and widths. The measured data also show good agreement with theoretical predictions of strain based upon continuum mechanical considerations, giving validity to both measurement techniques for the entire range of strain values. The dependence of Young's modulus and fracture strain on size has also been analyzed. The Young's modulus is determined using SEM and compared with that obtained by resonance-based methods. Both methods produced a Young's modulus value close to that of bulk silicon with values obtained by resonance-based methods being slightly lower. Fracture strain is analyzed in 40 sets of samples with different beam geometries, yielding values up to 3.6%. The increase in fracture strain with decreasing beam width is compared with previous reports. Finally, the role of the surface on the mechanical properties is analyzed using UV and visible lasers having different penetration depths in silicon. The observed dependence of Raman shift on laser wavelength is used to assess the thermal conductivity of deformed silicon.

  15. Strain variation in corrugated graphene

    NASA Astrophysics Data System (ADS)

    Wang, Xuanye; Tantiwanichapan, Khwanchai; Christopher, Jason; Paiella, Roberto; Swan, Anna

    2015-03-01

    Raman spectroscopy is a powerful non-destructive technique for analyzing strain in graphene. Recently there has been interest in making corrugated graphene devices with varying spatial wavelengths Λ for plasmonic and THz applications. Transferring graphene onto corrugated substrates introduces strain, which if there was perfect clamping (high fraction) would cause a periodic strain variation. However, the strain variation for pattern size smaller than the diffraction limit λ makes it hard to precisely model the strain distribution. Here we present a detailed study on how strain varies in corrugated graphene with sub-diffraction limit periodicity Λ < λ. Mechanically exfoliated graphene was deposited onto sinusoidal shape silicon dioxide gratings with Λ=400 nm period using the pick and place transfer technique. We observed that the graphene is not rigidly clamped, but partially slides to relieve the strain. We model the linewidth variation to extract the local strain variation as well as the sliding in the presence of charge puddling in graphene. The method gives us a better understanding on graphene slippage and strain distribution in graphene on a corrugated substrate with sub-diffraction limit spatial period.

  16. Emerging Enteropathogenic Escherichia coli Strains?

    PubMed Central

    Irino, Kinue; Girão, Dennys M.; Girão, Valéria B.C.; Guth, Beatriz E.C.; Vaz, Tânia M.I.; Moreira, Fabiana C.; Chinarelli, Silvia H.; Vieira, Mônica A.M.

    2004-01-01

    Escherichia coli strains of nonenteropathogenic serogroups carrying eae but lacking the enteropathogenic E. coli adherence factor plasmid and Shiga toxin DNA probe sequences were isolated from patients (children, adults, and AIDS patients) with and without diarrhea in Brazil. Although diverse in phenotype and genotype, some strains are potentially diarrheagenic. PMID:15504277

  17. Hypothetical strain-free oligoradicals

    PubMed Central

    Hoffmann, Roald; Eisenstein, Odile; Balaban, Alexandru T.

    1980-01-01

    Several new classes of oligoradicals free of angle strain are suggested and examined by means of molecular orbital calculations. The collapse products of these hypothetical radicals are highly strained molecules. Various electronic strategies for the stabilization of these oligoradicals have been explored. PMID:16592882

  18. Difference Between Strain and Sprain.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Provided in this description of the differences between a strain (damage to the muscle or tendon) and a sprain (damage to the ligament) are definitions of mild, moderate, and severe (first, second, and third degree) strains and sprains. A final caution is given that these are two separate and distinct problems and should be treated as such. (DC)

  19. [Repetition Strain Injury

    PubMed

    Ribeiro

    1997-01-01

    Muscular-skeletal disorders of the upper limbs resulting from work involving repetition strain (RSI) are now the most frequent work-related diseases in early or late industrialized countries. The author maintains that in addition to being work-related diseases, RSIs are symbolic illnesses revealing the contradictions and social pathogenesis of the new cycle of development and crisis in capitalist production. Discussing the social and historical dimensions of this process, the author insists that the low efficacy of technical interventions by labor engineering, ergonomics, and clinical medicine in the prevention, early and adequate diagnosis, and treatment of such post-modern illnesses and the difficulty in rehabilitating and reincorporating such workers reflect precisely a broader determination of health and illness, since the appropriation, incorporation, and use of technological innovations and the new forms of work management are defined according to the exclusive interests of capital. Thus, a growing contingent of young workers (mainly females) from different labor categories are losing or under threat of losing their health and work capacity, two essential and closely linked public values. The solution to the SRI issue must be political and collective. PMID:10886940

  20. High temperature strain measurement with a resistance strain gage

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen; Fichtel, ED; Mcdaniel, Amos

    1993-01-01

    A PdCr based electrical resistance strain gage was demonstrated in the laboratory to be a viable sensor candidate for static strain measurement at high temperatures. However, difficulties were encountered while transferring the sensor to field applications. This paper is therefore prepared for recognition and resolution of the problems likely to be encountered with PdCr strain gages in field applications. Errors caused by the measurement system, installation technique and lead wire attachment are discussed. The limitations and some considerations related to the temperature compensation technique used for this gage are also addressed.

  1. Recent advances in echocardiography: strain and strain rate imaging

    PubMed Central

    Mirea, Oana; Duchenne, Jurgen; Voigt, Jens-Uwe

    2016-01-01

    Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications. PMID:27158476

  2. Ferroelastic dynamics and strain compatibility

    NASA Astrophysics Data System (ADS)

    Lookman, T.; Shenoy, S. R.; Rasmussen, K. Ø.; Saxena, A.; Bishop, A. R.

    2003-01-01

    We derive underdamped evolution equations for the order-parameter (OP) strains of a proper ferroelastic material undergoing a structural transition, using Lagrangian variations with Rayleigh dissipation, and a free energy as a polynomial expansion in the N=n+Nop symmetry-adapted strains. The Nop strain equations are structurally similar in form to the Lagrange-Rayleigh one-dimensional strain dynamics of Bales and Gooding (BG), with “strain accelerations” proportional to a Laplacian acting on a sum of the free-energy strain derivative and frictional strain force assuming geometric linearity. The tensorial St. Venant’s elastic compatibility constraints that forbid defects, are used to determine the n non-order-parameter strains in terms of the OP strains, generating anisotropic and long-range OP contributions to the free energy, friction, and noise. The same OP equations are obtained by either varying the displacement vector components, or by varying the N strains subject to the Nc compatibility constraints. A Fokker-Planck equation, based on the BG dynamics in more than one dimension with noise terms, is set up. The BG dynamics corresponds to a set of nonidentical nonlinear (strain) oscillators labeled by wave vector k→, with competing short- and long-range couplings. The oscillators have different “strain-mass” densities ρ(k)˜1/k2 and dampings ˜1/ρ(k)˜k2, so the lighter large-k oscillators equilibrate first, corresponding to earlier formation of smaller-scale oriented textures. This produces a sequential-scale scenario for post-quench nucleation, elastic patterning, and hierarchical growth. Neglecting inertial effects yields a late-time dynamics for identifying extremal free-energy states, that is, of the time-dependent Ginzburg-Landau form, with nonlocal, anisotropic Onsager coefficients that become constants for special parameter values. We consider in detail the two-dimensional (2D) unit-cell transitions from a triangular to a centered

  3. Low TCR nanocomposite strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)

    2012-01-01

    A high temperature thin film strain gage sensor capable of functioning at temperatures above 1400.degree. C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

  4. High-temperature capacitive strain measurement system

    NASA Technical Reports Server (NTRS)

    Wilson, E. J.; Egger, R. L.

    1975-01-01

    Capacitive strain gage and signal conditioning system measures stress-induced strain and cancels thermal expansion strain at temperatures to 1,500 F (815 C). Gage does not significantly restrain or reinforce specimen.

  5. Anelastic Strain Recovery Analysis Code

    Energy Science and Technology Software Center (ESTSC)

    1995-04-05

    ASR4 is a nonlinear least-squares regression of Anelastic Strain Recovery (ASR) data for the purpose of determining in situ stress orientations and magnitudes. ASR4 fits the viscoelastic model of Warpinski and Teufel to measure ASR data, calculates the stress orientations directly, and stress magnitudes if sufficient input data are available. The code also calculates the stress orientation using strain-rosette equations, and it calculates stress magnitudes using Blanton''s approach, assuming sufficient input data are available.

  6. Bacterial Strain Diversity Within Wounds

    PubMed Central

    Kirkup, Benjamin C.

    2015-01-01

    Significance: Rare bacterial taxa (taxa of low relative frequency) are numerous and ubiquitous in virtually any sample—including wound samples. In addition, even the high-frequency genera and species contain multiple strains. These strains, individually, are each only a small fraction of the total bacterial population. Against the view that wounds contain relatively few kinds of bacteria, this newly recognized diversity implies a relatively high rate of migration into the wound and the potential for diversification during infection. Understanding the biological and medical importance of these numerous taxa is an important new element of wound microbiology. Recent Advances: Only recently have these numerous strains been discovered; the technology to detect, identify, and characterize them is still in its infancy. Multiple strains of both gram-negative and gram-positive bacteria have been found in a single wound. In the few cases studied, the distribution of the bacteria suggests microhabitats and biological interactions. Critical Issues: The distribution of the strains, their phenotypic diversity, and their interactions are still largely uncharacterized. The technologies to investigate this level of genomic detail are still developing and have not been largely deployed to investigate wounds. Future Directions: As advanced metagenomics, single-cell genomics, and advanced microscopy develop, the study of wound microbiology will better address the complex interplay of numerous individually rare strains with both the host and each other. PMID:25566411

  7. Optical Strain Measurement System Development

    NASA Technical Reports Server (NTRS)

    Lant, C. T.

    1985-01-01

    Investigations of physical phenomena affecting the durability of SSME components require measurement systems operational in hostile environments. The need for such instrumentation caused the definition and operation of an optical strain measurement system. This optical strain measurement system based on the speckle shift method is being developed. This is a noncontact, automatic method of measuring surface strain in one dimension that corrects for error due to rigid body motion. It provides a gauge length of 1 to 2 mm and allows the region of interest on the test specimen to be mapped point by point. The output is a graphics map of the points inspected on the specimen; data points is stored in quasi-real time. This is the first phase of a multiphase effort in optical strain measurement. The speckle pattern created by the test specimen is interpreted as high order interference fringes resulting from a random diffraction grating, being the natural surface roughness of the specimen. Strain induced on the specimen causes a change in spacing of the surface roughness, which in turn shifts the position of the interference pattern (speckles).

  8. Genome Sequence of Pseudomonas chlororaphis Strain 189

    PubMed Central

    Town, Jennifer; Audy, Patrice; Boyetchko, Susan M.

    2016-01-01

    Pseudomonas chlororaphis strain 189 is a potent inhibitor of the growth of the potato pathogen Phytophthora infestans. We determined the complete, finished sequence of the 6.8-Mbp genome of this strain, consisting of a single contiguous molecule. Strain 189 is closely related to previously sequenced strains of P. chlororaphis. PMID:27340063

  9. Measuring mine roof bolt strains

    DOEpatents

    Steblay, Bernard J.

    1986-01-01

    A mine roof bolt and a method of measuring the strain in mine roof bolts of this type are disclosed. According to the method, a flat portion on the head of the mine roof bolt is first machined. Next, a hole is drilled radially through the bolt at a predetermined distance from the bolt head. After installation of the mine roof bolt and loading, the strain of the mine roof bolt is measured by generating an ultrasonic pulse at the flat portion. The time of travel of the ultrasonic pulse reflected from the hole is measured. This time of travel is a function of the distance from the flat portion to the hole and increases as the bolt is loaded. Consequently, the time measurement is correlated to the strain in the bolt. Compensation for various factors affecting the travel time are also provided.

  10. Spin transport in graphene superlattice under strain

    NASA Astrophysics Data System (ADS)

    Sattari, Farhad

    2016-09-01

    In this paper, the spin-dependent transport and the spin polarization properties for graphene superlattice with Rashba spin-orbit interaction (RSOI) in the presence of zigzag and armchair direction strain are studied. It is found that for the zigzag direction strain the angular range of the spin-inversion can be efficiently controlled by the strain strength. In addition, the efficiency of spin-inversion and spin-dependent conductivity decreases by increasing the strain strength. When the armchair direction strain is applied to a monolayer graphene superlattice the spin polarization can be observed and increases by increasing the strain strength, whereas for the zigzag direction strain it is zero.

  11. Taxonomy of oxalotrophic Methylobacterium strains

    NASA Astrophysics Data System (ADS)

    Sahin, Nurettin; Kato, Yuko; Yilmaz, Ferah

    2008-10-01

    Most of the oxalotrophic bacteria are facultative methylotrophs and play important ecological roles in soil fertility and cycling of elements. This study gives a detailed picture of the taxonomy and diversity of these bacteria and provides new information about the taxonomical variability within the genus Methylobacterium. Twelve mesophilic, pink-pigmented, and facultatively methylotrophic oxalate-oxidizing strains were included in this work that had been previously isolated from the soil and some plant tissues by the potassium oxalate enrichment method. The isolates were characterized using biochemical tests, cellular lipid profiles, spectral characteristics of carotenoid pigments, G+C content of the DNA, and 16S rDNA sequencing. The taxonomic similarities among the strains were analyzed using the simple matching ( S SM) and Jaccard ( S J) coefficients, and the UPGMA clustering algorithm. The phylogenetic position of the strains was inferred by the neighbor-joining method on the basis of the 16S rDNA sequences. All isolates were Gram-negative, facultatively methylotrophic, oxidase and catalase positive, and required no growth factors. Based on the results of numerical taxonomy, the strains formed four closely related clusters sharing ≥85% similarity. Analysis of the 16S rDNA sequences demonstrated that oxalotrophic, pink-pigmented, and facultatively methylotrophic strains could be identified as members of the genus Methylobacterium. Except for M. variabile and M. aquaticum, all of the Methylobacterium type strains tested had the ability of oxalate utilization. Our results indicate that the capability of oxalate utilization seems to be an uncommon trait and could be used as a valuable taxonomic criterion for differentiation of Methylobacterium species.

  12. Photoacoustic spectroscopy of Entamoeba histolytica strains

    NASA Astrophysics Data System (ADS)

    Acosta-Avalos, D.; Alvarado-Gil, J. J.; Silva, E. F.; Orozco, E.; de Menezes, L. F.; Vargas, H.

    2005-06-01

    Pathogenic and non-pathogenic strains of E. histolytica are studied using photoacoustic spectroscopy. It is shown that the pathogenic strain presents a spectrum similar to that of iron sulfur proteins. The non-pathogenic strain does not show any relevant absorption at the studied wavelength range. The differences observed between the optical absorption spectra of both strains opens the possibility of using photoacoustic spectroscopy as a reliable and simple technique to identify different types of E. histolytica strains.

  13. Trials with a Strain Gauge.

    ERIC Educational Resources Information Center

    Auty, Geoff

    1996-01-01

    Describes an attempt to match the goals of the practical demonstration of the use of a strain gauge and the technical applications of science and responding to student questions in early trials, while keeping within the level of electronics in advanced physics. (Author/JRH)

  14. Virulence of 32 Salmonella Strains in Mice

    PubMed Central

    Swearingen, Matthew C.; Porwollik, Steffen; Desai, Prerak T.; McClelland, Michael; Ahmer, Brian M. M.

    2012-01-01

    Virulence and persistence in the BALB/c mouse gut was tested for 32 strains of Salmonella enterica for which genome sequencing is complete or underway, including 17 serovars within subspecies I (enterica), and two representatives of each of the other five subspecies. Only serovar Paratyphi C strain BAA1715 and serovar Typhimurium strain 14028 were fully virulent in mice. Three divergent atypical Enteritidis strains were not virulent in BALB/c, but two efficiently persisted. Most of the other strains in all six subspecies persisted in the mouse intestinal tract for several weeks in multiple repeat experiments although the frequency and level of persistence varied considerably. Strains with heavily degraded genomes persisted very poorly, if at all. None of the strains tested provided immunity to Typhimurium infection. These data greatly expand on the known significant strain-to-strain variation in mouse virulence and highlight the need for comparative genomic and phenotypic studies. PMID:22558320

  15. Extremophiles and their application to veterinary medicine.

    PubMed

    Irwin, Jane Ann

    2010-01-01

    Extremophiles can be defined as organisms that can survive in extreme environments that cannot support mammalian life. They include microorganisms that can tolerate temperature extremes, extremes of pH, salinity, hydrostatic pressure and ionizing radiation, as well as low oxygen tension, desiccation and the presence of heavy metals. Psychrophilic organisms also include fish in polar waters and animals that withstand freezing. Rare examples of thermophilic pathogens exist, and the main category of extremophilic animal pathogens comprises psychrophilic and psychrotrophic microorganisms that cause fish diseases, e.g. Flavobacterium psychrophilum, Moritella viscosa, Aliivibrio wodanis and Aliivibrio salmonicida. The most widely known application of an extremophile product in veterinary medicine is DNA polymerase from thermophiles, which is a mainstay of PCR-based diagnostics for an extensive range of animal pathogens. DNA polymerases and other extremophile enzymes are also used in many molecular biology applications and animal genomics. Other extremophile products may find application in veterinary medicine in the future. These include enzymes in biosensors, compatible solutes in skin care products, drug excipients, treatments for respiratory disease, radioprotectants, peptide antibiotics, archaeal lipids for drug delivery and anti-cancer therapeutics. PMID:20662377

  16. Mapping microscale strain heterogeneity during creep deformation

    NASA Astrophysics Data System (ADS)

    Quintanilla Terminel, A.; Evans, J.

    2013-12-01

    We use a new technique combining microfabrication technology and compression tests to map the strain field at a micrometric scale in polycrystalline materials. This technique allows us to map local strain while measuring macroscopic strain and rheological properties, and provides insight into the relative contribution of various plasticity mechanisms under varying creep conditions. The micro-strain mapping technique was applied to Carrara Marble under different deformation regimes, at 300 MPa and temperatures ranging from 200 to 700 °C. At 600 °C, strain of 10%, and strain rate of 3e-5s-1, the local strain at twin and grain boundaries is up to 5 times greater than the average sample strain. At these conditions, strains averaged across a particular grain may vary by as much as 100%, but the strain field becomes more homogeneous with increasing strain. For example, for the analyzed experiments, the average wavelength of the strain heterogeneity is 70 micrometers at 10% strain, but increases to 110 micrometers at 20%. For a strain of 10%, heterogeneity is increased at slower strain rate (at 1e-5s-1). This increase seems to be associated with a more important role of twin boundary and grain boundary migration. As expected, twin densities are markedly greater at the lower temperature, though it is still unclear whether the relative twin volume is greater. However, twin strains are still important at 600 °C and accommodate an average of 14 % of the total strain at 10% deformation and a strain rate of 3e-5s-1.

  17. Material mechanical characterization method for multiple strains and strain rates

    DOEpatents

    Erdmand, III, Donald L.; Kunc, Vlastimil; Simunovic, Srdjan; Wang, Yanli

    2016-01-19

    A specimen for measuring a material under multiple strains and strain rates. The specimen including a body having first and second ends and a gage region disposed between the first and second ends, wherein the body has a central, longitudinal axis passing through the first and second ends. The gage region includes a first gage section and a second gage section, wherein the first gage section defines a first cross-sectional area that is defined by a first plane that extends through the first gage section and is perpendicular to the central, longitudinal axis. The second gage section defines a second cross-sectional area that is defined by a second plane that extends through the second gage section and is perpendicular to the central, longitudinal axis and wherein the first cross-sectional area is different in size than the second cross-sectional area.

  18. Modelling to very high strains

    NASA Astrophysics Data System (ADS)

    Bons, P. D.; Jessell, M. W.; Griera, A.; Evans, L. A.; Wilson, C. J. L.

    2009-04-01

    Ductile strains in shear zones often reach extreme values, resulting in typical structures, such as winged porphyroclasts and several types of shear bands. The numerical simulation of the development of such structures has so far been inhibited by the low maximum strains that numerical models can normally achieve. Typical numerical models collapse at shear strains in the order of one to three. We have implemented a number of new functionalities in the numerical platform "Elle" (Jessell et al. 2001), which significantly increases the amount of strain that can be achieved and simultaneously reduces boundary effects that become increasingly disturbing at higher strain. Constant remeshing, while maintaining the polygonal phase regions, is the first step to avoid collapse of the finite-element grid required by finite-element solvers, such as Basil (Houseman et al. 2008). The second step is to apply a grain-growth routine to the boundaries of polygons that represent phase regions. This way, the development of sharp angles is avoided. A second advantage is that phase regions may merge or become separated (boudinage). Such topological changes are normally not possible in finite element deformation codes. The third step is the use of wrapping vertical model boundaries, with which optimal and unchanging model boundaries are maintained for the application of stress or velocity boundary conditions. The fourth step is to shift the model by a random amount in the vertical direction every time step. This way, the fixed horizontal boundary conditions are applied to different material points within the model every time step. Disturbing boundary effects are thus averaged out over the whole model and not localised to e.g. top and bottom of the model. Reduction of boundary effects has the additional advantage that model can be smaller and, therefore, numerically more efficient. Owing to the combination of these existing and new functionalities it is now possible to simulate the

  19. Strains

    MedlinePlus

    Pulled muscle ... can include: Pain and difficulty moving the injured muscle Discolored and bruised skin Swelling ... if you still have pain. Rest the pulled muscle for at least a day. If possible, keep ...

  20. Strain tolerant microfilamentary superconducting wire

    DOEpatents

    Finnemore, D.K.; Miller, T.A.; Ostenson, J.E.; Schwartzkopf, L.A.; Sanders, S.C.

    1993-02-23

    A strain tolerant microfilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

  1. Computational strain gradient crystal plasticity

    NASA Astrophysics Data System (ADS)

    Niordson, Christian F.; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale.

  2. High Temperature Capacitive Strain Gage

    NASA Technical Reports Server (NTRS)

    Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.

    1990-01-01

    Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

  3. Strain stiffening in collagen I networks.

    PubMed

    Motte, Stéphanie; Kaufman, Laura J

    2013-01-01

    Biopolymer gels exhibit strain stiffening that is generally not seen in synthetic gels. Here, we investigate the strain-stiffening behavior in collagen I gels that demonstrate elasticity derived from a variety of sources including crosslinking through telopeptides, bundling through low-temperature gelation, and exogenous crosslinking with genipin. In all cases, it is found that these gels exhibit strain stiffening; in general, onset of strain stiffening occurs earlier, yield strain is lower, and degree of strain stiffening is smaller in higher concentration gels and in those displaying thick fibril bundles. Recovery after exposure to high strains is substantial and similar in all gels, suggesting that much of the stiffening comes from reversible network deformations. A key finding of this study is that collagen I gels of identical storage and loss moduli may display different nonlinear responses and different capacities to recover from high strain. PMID:23097228

  4. Design of a strain-gage probe

    NASA Technical Reports Server (NTRS)

    Kolba, V. M.; Vetter, D. L.

    1969-01-01

    Strain-gage spacer probe uses the deflection of a leaf spring to measure strain in a long, slender beam nondestructively. The selected gage is of the smallest practical size, as thin as possible and yet of a standard type.

  5. Turbulent Plane Wakes Subjected to Successive Strains

    NASA Technical Reports Server (NTRS)

    Rogers, Michael M.

    2003-01-01

    Six direct numerical simulations of turbulent time-evolving strained plane wakes have been examined to investigate the response of a wake to successive irrotational plane strains of opposite sign. The orientation of the applied strain field has been selected so that the flow is the time-developing analogue of a spatially developing wake evolving in the presence of either a favourable or an adverse streamwise pressure gradient. The magnitude of the applied strain rate a is constant in time t until the total strain e(sup at) reaches about four. At this point, a new simulation is begun with the sign of the applied strain being reversed (the original simulation is continued as well). When the total strain is reduced back to its original value of one, yet another simulation is begun with the sign of the strain being reversed again back to its original sign. This process is done for both initially "favourable" and initially "adverse" strains, providing simulations for each of these strain types from three different initial conditions. The evolution of the wake mean velocity deficit and width is found to be very similar for all the adversely strained cases, with both measures rapidly achieving exponential growth at the rate associated with the cross-stream expansive strain e(sup at). In the "favourably" strained cases, the wake widths approach a constant and the velocity deficits ultimately decay rapidly as e(sup -2at). Although all three of these cases do exhibit the same asymptotic exponential behaviour, the time required to achieve this is longer for the cases that have been previously adversely strained (by at approx. equals 1). These simulations confirm the generality of the conclusions drawn in Rogers (2002) regarding the response of plane wakes to strain. The evolution of strained wakes is not consistent with the predictions of classical self-similar analysis; a more general equilibrium similarity solution is required to describe the results. At least for the cases

  6. Piezoelectric field in strained GaAs.

    SciTech Connect

    Chow, Weng Wah; Wieczorek, Sebastian Maciej

    2005-11-01

    This report describes an investigation of the piezoelectric field in strained bulk GaAs. The bound charge distribution is calculated and suitable electrode configurations are proposed for (1) uniaxial and (2) biaxial strain. The screening of the piezoelectric field is studied for different impurity concentrations and sample lengths. Electric current due to the piezoelectric field is calculated for the cases of (1) fixed strain and (2) strain varying in time at a constant rate.

  7. Temperature-Compensating Inactive Strain Gauge

    NASA Technical Reports Server (NTRS)

    Moore, Thomas C., Sr.

    1993-01-01

    Thermal contribution to output of active gauge canceled. High-temperature strain gauges include both active gauge wires sensing strains and inactive gauge wires providing compensation for thermal contributions to gauge readings. Inactive-gauge approach to temperature compensation applicable to commercially available resistance-type strain gauges operating at temperatures up to 700 degrees F and to developmental strain gauges operating at temperatures up to 2,000 degrees F.

  8. Installing strain gauges on composite material

    NASA Astrophysics Data System (ADS)

    Shull, Larry

    The evolution of the strain gage is traced and problems associated with their use on composite materials are discussed. It is believed that the use of the computer in strain gage data systems has caused some of the attitude problems in measuring strains in composite materials. The performance of strain gages on filament-wound Kevlar pressure vessels is discussed as well as graphite composites during 1984-1986, surface preparation, gage location alignment.

  9. Strain Monitoring of Flexible Structures

    NASA Technical Reports Server (NTRS)

    Litteken, Douglas A.

    2017-01-01

    , such as tensile testing, fatigue testing, and shear testing, but common measurement techniques cannot be used on fabric. Measuring strain in a material and during a test is a critical parameter for an engineer to monitor the structure during the test and correlate to an analytical model. The ability to measure strain in fabric structures is a challenge for NASA. Foil strain gauges, for example, are commonplace on metallic structures testing, but are extremely difficult to interface with a fabric substrate. New strain measuring techniques need to be developed for use with fabric structures. This paper investigates options for measuring strain in fabric structures for both ground testing and in-space structural health monitoring. It evaluates current commercially available options and outlines development work underway to build custom measurement solutions for NASA's fabric structures.

  10. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains

    PubMed Central

    Gangaiah, Dharanesh; Webb, Kristen M.; Humphreys, Tricia L.; Fortney, Kate R.; Toh, Evelyn; Tai, Albert; Katz, Samantha S.; Pillay, Allan; Chen, Cheng-Yen; Roberts, Sally A.; Munson, Robert S.; Spinola, Stanley M.

    2015-01-01

    Background Although cutaneous ulcers (CU) in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU) and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin? Methodology/Principal Findings To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya) and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin. Conclusions/Significance These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions. PMID:26147869

  11. Modal strain energies in COSMIC NASTRAN

    NASA Technical Reports Server (NTRS)

    Snyder, B. D.; Venkayya, V. B.

    1989-01-01

    A computer program was developed to take a NASTRAN output file from a normal modes analysis and calculate the modal strain energies of selected elements. The FORTRAN program can determine the modal strain energies for CROD, CBAR, CELAS, CTRMEM, CQDMEM2, and CSHEAR elements. Modal strain energies are useful in estimating damping in structures.

  12. Strains and Sprains Are a Pain

    MedlinePlus

    ... move the injured part, and you may even think you have broken a bone . How Does a Strain or Sprain Happen? Strains often happen when you put a lot of pressure on a muscle or you push it too far, such as when lifting a heavy object. Strains can be more likely to happen if ...

  13. Strainrange partitioning: A total strain range version

    NASA Technical Reports Server (NTRS)

    Halford, G. R.; Saltsman, J. F.

    1983-01-01

    Procedures are presented for expressing the Strainrange Partitioning (SRP) method for creep fatigue life prediction in terms of total strain range. Inelastic and elastic strain-range - life relations are summed to give total strain-range - life relations. The life components due to inelastic strains are dealt with using conventional SRP procedures while the life components due to elastic strains are expressed as families of time-dependent terms for each type of SRP cycle. Cyclic constitutive material behavior plays an important role in establishing the elastic strain-range - life relations as well as the partitioning of the inelastic strains. To apply the approach, however, it is not necessary to have to determine the magnitude of the inelastic strain range. The total strain SRP approach is evaluated and verified using two nickel base superalloys, AF2-1DA and Rene 95. Excellent agreement is demonstrated between observed and predicted cyclic lifetimes with 70 to 80 percent of the predicted lives falling within factors of two of the observed lives. The total strain-range SRP approach should be of considerable practical value to designers who are faced with creep-fatigue problems for which the inelastic strains cannot be calculated with sufficient accuracy to make reliable life predictions by the conventional inelastic strain range SRP approach.

  14. Siderotyping of Antarctic fluorescent Pseudomonas strains.

    PubMed

    Geoffroy, V A; Meyer, J M

    2004-07-01

    Five fluorescent Pseudomonas strains isolated from Antarctica have been previously recognized as producing three structurally different pyoverdines. In the present work, siderotyping procedures have been used to classify these strains, together with 1282 isolates of different origins, into siderovars. The strain biodiversity encountered within each siderovar, as well as the potential taxonomic value of the siderovars, are described and discussed. It is concluded that a majority of antarctic strains are commonly distributed worldwide. One strain, however, presenting a particular pyoverdine structure found in a unique other isolate, was apparently much more specific to cold environment. PMID:15559975

  15. Progress in optical strain measurement system development

    NASA Technical Reports Server (NTRS)

    Lant, Christian T.; Qaqish, Walid

    1987-01-01

    A laser speckle strain measurement system has been built and tested for the NASA Lewis Research Center. The system is based on a speckle shift technique, which automatically corrects for error due to rigid body motion, and provides a near real time measure of strain. The first stage of a multiphase effort to develop an optical strain gauge capable of mapping in two dimensions the strain on the surface of a hot specimen is discussed. The objectives of this first phase have been to provide a noncontact, one-dimensional, differential strain gauge for experimental purposes, and to determine the maximum open air temperature limit of the system.

  16. Strain Engineering of Transition Metal Dichalcogenides

    NASA Astrophysics Data System (ADS)

    Dadgar, Ali; Pasupathy, Abhay; Herman, Irving; Wang, Dennis; Kang, Kyungnam; Yang, Eui-Hyeok

    The application of strain to materials can cause changes to bandwidth, effective masses, degeneracies and even structural phases. In the case of the transition metal dichalcogenide (TMD) semiconductors, small strain (around 1 percent) is expected to change band gaps and mobilities, while larger strains are expected to cause phase changes from the triangular 2H phase to orthorhombic 1T' phases. We will describe experimental techniques to apply small and large (around 10 percent) strains to one or few layer samples of the TMD semiconductors, and describe the effect of the strain using optical (Raman, photoluminescence) and cryogenic transport techniques.

  17. Demonstration test of burner liner strain measurements using resistance strain gages

    NASA Technical Reports Server (NTRS)

    Grant, H. P.; Anderson, W. L.

    1984-01-01

    A demonstration test of burner liner strain measurements using resistance strain gages as well as a feasibility test of an optical speckle technique for strain measurement are presented. The strain gage results are reported. Ten Kanthal A-1 wire strain gages were used for low cycle fatigue strain measurements to 950 K and .002 apparent strain on a JT12D burner can in a high pressure (10 atmospheres) burner test. The procedure for use of the strain gages involved extensive precalibration and postcalibration to correct for cooling rate dependence, drift, and temperature effects. Results were repeatable within + or - .0002 to .0006 strain, with best results during fast decels from 950 K. The results agreed with analytical prediction based on an axisymmetric burner model, and results indicated a non-uniform circumferential distribution of axial strain, suggesting temperature streaking.

  18. Strain flexibility identification of bridges from long-gauge strain measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Xia, Qi; Cheng, YuYao; Wu, ZhiShen

    2015-10-01

    Strain flexibility, defined as the strain response of a structure's element to a unit input force, is import for structural safety evaluation, but its identification is seldom investigated. A novel long-gauge fiber optic sensor has been developed to measure the averaged strain within a long gauge length. Its advantage of measuring both local and global information of the structure offers an excellent opportunity of developing the strain flexibility identification theory. In this article, the method to identify structural strain flexibility from long-gauge dynamic strain measurements is proposed. It includes the following main steps: (a) macro strain frequency response function (FRF) estimation from macro strain measurements and its feature characterization; (b) general strain modal parameter identification; (c) scaling factor calculation, and (d) strain flexibility identification. Numerical and experimental examples successfully verify the effectiveness of the proposed method.

  19. Job Strain in Physical Therapists

    PubMed Central

    Campo, Marc A.; Weiser, Sherri; Koenig, Karen L.

    2009-01-01

    Background: Job stress has been associated with poor outcomes. In focus groups and small-sample surveys, physical therapists have reported high levels of job stress. Studies of job stress in physical therapy with larger samples are needed. Objective: The purposes of this study were: (1) to determine the levels of psychological job demands and job control reported by physical therapists in a national sample, (2) to compare those levels with national norms, and (3) to determine whether high demands, low control, or a combination of both (job strain) increases the risk for turnover or work-related pain. Design: This was a prospective cohort study with a 1-year follow-up period. Methods: Participants were randomly selected members of the American Physical Therapy Association (n=882). Exposure assessments included the Job Content Questionnaire (JCQ), a commonly used instrument for evaluation of the psychosocial work environment. Outcomes included job turnover and work-related musculoskeletal disorders. Results: Compared with national averages, the physical therapists reported moderate job demands and high levels of job control. About 16% of the therapists reported changing jobs during follow-up. Risk factors for turnover included high job demands, low job control, job strain, female sex, and younger age. More than one half of the therapists reported work-related pain. Risk factors for work-related pain included low job control and job strain. Limitations: The JCQ measures only limited dimensions of the psychosocial work environment. All data were self-reported and subject to associated bias. Conclusions: Physical therapists’ views of their work environments were positive, including moderate levels of demands and high levels of control. Those therapists with high levels of demands and low levels of control, however, were at increased risk for both turnover and work-related pain. Physical therapists should consider the psychosocial work environment, along with other

  20. Straining Graphene Using Thin Film Shrinkage Methods

    PubMed Central

    2014-01-01

    Theoretical works suggest the possibility and usefulness of strain engineering of graphene by predicting remarkable properties, such as Dirac cone merging, bandgap opening and pseudo magnetic field generation. However, most of these predictions have not yet been confirmed because it is experimentally difficult to control the magnitude and type (e.g., uniaxial, biaxial, and so forth) of strain in graphene devices. Here we report two novel methods to apply strain without bending the substrate. We employ thin films of evaporated metal and organic insulator deposited on graphene, which shrink after electron beam irradiation or heat application. These methods make it possible to apply both biaxial strain and in-plane isotropic compressive strain in a well-controlled manner. Raman spectroscopy measurements show a clear splitting of the degenerate states of the G-band in the case of biaxial strain, and G-band blue shift without splitting in the case of in-plane isotropic compressive strain. In the case of biaxial strain application, we find out the ratio of the strain component perpendicular to the stretching direction is at least three times larger than what was previously observed, indicating that shrinkage of the metal or organic insulator deposited on graphene induces both tensile and compressive strain in this atomically thin material. Our studies present for the first time a viable way to apply strain to graphene without the need to bend the substrate. PMID:24490629

  1. Straining graphene using thin film shrinkage methods.

    PubMed

    Shioya, Hiroki; Craciun, Monica F; Russo, Saverio; Yamamoto, Michihisa; Tarucha, Seigo

    2014-03-12

    Theoretical works suggest the possibility and usefulness of strain engineering of graphene by predicting remarkable properties, such as Dirac cone merging, bandgap opening and pseudo magnetic field generation. However, most of these predictions have not yet been confirmed because it is experimentally difficult to control the magnitude and type (e.g., uniaxial, biaxial, and so forth) of strain in graphene devices. Here we report two novel methods to apply strain without bending the substrate. We employ thin films of evaporated metal and organic insulator deposited on graphene, which shrink after electron beam irradiation or heat application. These methods make it possible to apply both biaxial strain and in-plane isotropic compressive strain in a well-controlled manner. Raman spectroscopy measurements show a clear splitting of the degenerate states of the G-band in the case of biaxial strain, and G-band blue shift without splitting in the case of in-plane isotropic compressive strain. In the case of biaxial strain application, we find out the ratio of the strain component perpendicular to the stretching direction is at least three times larger than what was previously observed, indicating that shrinkage of the metal or organic insulator deposited on graphene induces both tensile and compressive strain in this atomically thin material. Our studies present for the first time a viable way to apply strain to graphene without the need to bend the substrate. PMID:24490629

  2. Numerical demonstration of MEMS strain sensor

    NASA Astrophysics Data System (ADS)

    Saboonchi, Hossain; Ozevin, Didem

    2012-04-01

    Silicon has piezoresistive property that allows designing strain sensor with higher gauge factor compared to conventional metal foil gauges. The sensing element can be micro-scale using MEMS, which minimizes the effect of strain gradient on measurement at stress concentration regions such as crack tips. The challenge of MEMS based strain sensor design is to decouple the sensing element from substrate for true strain measurement and to compensate the temperature effect on the piezoresistive coefficients of silicon. In this paper, a family of MEMS strain sensors with different geometric designs is introduced. Each strain sensor is made of single crystal silicon and manufactured using deposition/ etching/oxidation steps on a n- doped silicon wafer in (100) plane. The geometries include sensing element connected to the free heads of U shape substrate, a set of two or more sensing elements in an array in order to capture strain gradients and two directional sensors. The response function and the gauge factor of the strain sensors are identified using multi-physics models that combine structural and electrical behaviors of sensors mounted on a strained structure. The relationship between surface strain and strain at microstructure is identified numerically in order to include the relationship in the response function calculation.

  3. Thick film wireless and powerless strain sensor

    NASA Astrophysics Data System (ADS)

    Jia, Yi; Sun, Ke

    2006-03-01

    The development of an innovative wireless strain sensing technology has a great potential to extend its applications in manufacturing, civil engineering and aerospace industry. This paper presents a novel wireless and powerless strain sensor with a multi-layer thick film structure. The sensor employs a planar inductor (L) and capacitive transducer (C) resonant tank sensing circuit, and a strain sensitive material of a polarized polyvinylidene fluoride (PVDF) piezoelectric thick film to realize the wireless strain sensing by strain to frequency conversion and to receive radio frequency electromagnetic energy for powering the sensor. The prototype sensor was designed and fabricated. The results of calibration on a strain constant cantilever beam show a great linearity and sensitivity about 0.0013 in a strain range of 0-0.018.

  4. Strain engineering of graphene: a review

    NASA Astrophysics Data System (ADS)

    Si, Chen; Sun, Zhimei; Liu, Feng

    2016-02-01

    Graphene has intrigued the science community by many unique properties not found in conventional materials. In particular, it is the strongest two-dimensional material ever measured, being able to sustain reversible tensile elastic strain larger than 20%, which yields an interesting possibility to tune the properties of graphene by strain and thus opens a new field called ``straintronics''. In this article, the current progress in the strain engineering of graphene is reviewed. We first summarize the strain effects on the electronic structure and Raman spectra of graphene. We then highlight the electron-phonon coupling greatly enhanced by the biaxial strain and the strong pseudomagnetic field induced by the non-uniform strain with specific distribution. Finally, the potential application of strain-engineering in the self-assembly of foreign atoms on the graphene surface is also discussed. Given the short history of graphene straintronics research, the current progress has been notable, and many further advances in this field are expected.

  5. Differential receptor usage by measles virus strains.

    PubMed

    Bartz, R; Firsching, R; Rima, B; ter Meulen, V; Schneider-Schaulies, J

    1998-05-01

    Recently, we demonstrated that infection of cells with all measles virus (MV) strains tested was inhibited by antibodies against CD46, although not all strains caused downregulation of the MV receptor CD46 from the surface of human cells. We now show that infection of cells with MV strain WTFb, a variant of wild-type isolate WTF which has been isolated and propagated on human BJAB cells, is not inhibited by antibodies against CD46. In contrast, infection of cells with the closely related strain WTFv, a Vero cell-adapted variant of WTF, is inhibited by antibodies against CD46. This observation led us to investigate the interaction of these viruses and the vaccine strain Edmonston (Edm) with CD46 and target cells. Cellular receptors with high affinity binding for WTFb are present on BJAB cells, but not on transfected CD46-expressing CHO cells. In contrast to the Edm strain, virus particles and solubilized envelope glycoproteins of WTFb have a very limited binding capacity to CD46. Furthermore, we show that recombinant soluble CD46 either does not bind, or binds very weakly, to WTFb glycoproteins expressed on the cell surface. Our findings indicate that wild-type MV strain WTFb and vaccine strain Edm use different binding sites on human cells. In addition, the results suggest that MV strains may alternatively use CD46 and an unknown molecule as receptors, and that the degree of usage of both receptors may be MV strain-specific. PMID:9603316

  6. Comparison of Strain Rosettes and Digital Image Correlation for Measuring Vertebral Body Strain.

    PubMed

    Gustafson, Hannah; Siegmund, Gunter; Cripton, Peter

    2016-05-01

    Strain gages are commonly used to measure bone strain, but only provide strain at a single location. Digital image correlation (DIC) is an optical technique that provides the displacement, and therefore strain, over an entire region of interest on the bone surface. This study compares vertebral body strains measured using strain gages and DIC. The anterior surfaces of 15 cadaveric porcine vertebrae were prepared with a strain rosette and a speckled paint pattern for DIC. The vertebrae were loaded in compression with a materials testing machine, and two high-resolution cameras were used to image the anterior surface of the bones. The mean noise levels for the strain rosette and DIC were 1 με and 24 με, respectively. Bland-Altman analysis was used to compare strain from the DIC and rosette (excluding 44% of trials with some evidence of strain rosette failure or debonding); the mean difference ± 2 standard deviations (SDs) was -108 με ± 702 με for the minimum (compressive) principal strain and -53 με ± 332 με for the maximum (tensile) principal strain. Although the DIC has higher noise, it avoids the relatively high risk we observed of strain gage debonding. These results can be used to develop guidelines for selecting a method to measure strain on bone. PMID:26902321

  7. Fiber-optic polarimetric strain gauge

    NASA Astrophysics Data System (ADS)

    Bock, Wojtek J.; Wolinski, Tomasz R.

    A prototype fiber-optic polarimetric strain gauge based on the polarization mode coupling that occurs in highly birefringent optical fibers under the influence of axial strain is presented. Measurement set-up for a bonded strain gauge and its metrological characteristics are discussed together with the interpretation of observed physical effects in terms of changes in beat-length parameter under axial strain. The device is far more sensitive than conventional strain gauges, and can also be readily adjusted to a specified range of strain through an appropriate choice of fiber length and optical signal wavelength. The temperature drift of the device can be compensated in a straightforward procedure. The device is immune to electromagnetic interference, and is intrinsically safe in electrically dangerous, hazardous or explosive environments. Another attraction of this technology is its direct compatibility with fiber-optic telemetry, optical data transmission systems and multiplexing / demultiplexing technology.

  8. Sensor for Measuring Strain in Textile

    PubMed Central

    Mattmann, Corinne; Clemens, Frank; Tröster, Gerhard

    2008-01-01

    In this paper a stain sensor to measure large strain (80%) in textiles is presented. It consists of a mixture of 50wt-% thermoplastic elastomer (TPE) and 50wt-% carbon black particles and is fiber-shaped with a diameter of 0.315mm. The attachment of the sensor to the textile is realized using a silicone film. This sensor configuration was characterized using a strain tester and measuring the resistance (extension-retraction cycles): It showed a linear resistance response to strain, a small hysteresis, no ageing effects and a small dependance on the strain velocity. The total mean error caused by all these effects was ±5.5% in strain. Washing several times in a conventional washing machine did not influence the sensor properties. The paper finishes by showing an example application where 21 strain sensors were integrated into a catsuit. With this garment, 27 upper body postures could be recognized with an accuracy of 97%.

  9. Determining Micromechanical Strain in Nitinol

    SciTech Connect

    Strasberg, Matthew; /SLAC

    2006-09-27

    Nitinol is a superelastic alloy made of equal parts nickel and titanium. Due to its unique shape memory properties, nitinol is used to make medical stents, lifesaving devices used to allow blood flow in occluded arteries. Micromechanical models and even nitinol-specific finite element analysis (FEA) software are insufficient for unerringly predicting fatigue and resultant failure. Due to the sensitive nature of its application, a better understanding of nitinol on a granular scale is being pursued through X-ray diffraction techniques at the Stanford Synchrotron Radiation Laboratory (SSRL) at the Stanford Linear Accelerator Center (SLAC). Through analysis of powder diffraction patterns of nitinol under increasing tensile loads, localized strain can be calculated. We compare these results with micromechanical predictions in order to advance nitinol-relevant FEA tools. From this we hope to gain a greater understanding of how nitinol fatigues under multi-axial loads.

  10. Modeling competition between yeast strains

    NASA Astrophysics Data System (ADS)

    de Gee, Maarten; van Mourik, Hilda; de Visser, Arjan; Molenaar, Jaap

    2016-04-01

    We investigate toxin interference competition between S. cerevisiae colonies grown on a solid medium. In vivo experiments show that the outcome of this competition depends strongly on nutrient availability and cell densities. Here we present a new model for S. cerevisiae colonies, calculating the local height and composition of the colonies. The model simulates yeast colonies that show a good fit to experimental data. Simulations of colonies that start out with a homogeneous mixture of toxin producing and toxin sensitive cells can display remarkable pattern formation, depending on the initial ratio of the strains. Simulations in which the toxin producing and toxin sensitive species start at nearby positions clearly show that toxin production is advantageous.

  11. An experimental evaluation of apparent strain from foil strain gauges attached to carbon composite substrates

    NASA Technical Reports Server (NTRS)

    Scott, B. R.; Lanius, S. J.; Auer, C. W.

    1987-01-01

    An experimental evaluation of apparent thermal strains is conducted using various combinations of substrate/gauge/attachment structure and redundant high temperature extensometry. It is found that the extensometry could either confirm independent measurements of the substrate's thermal expansion, or quantify nonzero mechanical strains resulting from uncertain material behavior and boundary conditions. Apparent strain and thermal expansion behavior data can then be used to modify the raw strain measurements in order to determine either stress producing or total strains. Limitation of the correction procedure for the three selected strain gauges is noted which is due to relatively large gauge/attachment variability.

  12. Mechanical strain and degradation of laser heterostructures

    NASA Astrophysics Data System (ADS)

    Ptashchenko, Alexander A.; Ptashchenko, Fedor A.; Maslejeva, Natalia V.; Sadova, Galina V.

    2001-02-01

    The effect of mechanical strain on degradation processes in GaAs-AlGaAs laser heterostructures (LHS) with stripe geometry and in light emitting diodes (LED) was experimentally studied. The strain was produced either by axial pressure or by indentation with a Wickers pyramid. We show that degradation affects the degree of polarization and the far-field distribution of laser emission. The effect of strain on the degradation intensity is estimated.

  13. Polyphasic characterization of xanthomonas strains from onion.

    PubMed

    Gent, David H; Schwartz, Howard F; Ishimaru, Carol A; Louws, Frank J; Cramer, Robert A; Lawrence, Christopher B

    2004-02-01

    ABSTRACT Xanthomonas leaf blight has become an increasingly important disease of onion, but the diversity among Xanthomonas strains isolated from onion is unknown, as is their relationship to other species and pathovars of Xanthomonas. Forty-nine Xanthomonas strains isolated from onion over 27 years from 10 diverse geographic regions were characterized by pathogenicity to onion and dry bean, fatty acid profiles, substrate utilization patterns (Biolog), bactericide resistance, repetitive sequence-based polymerase chain reaction fingerprinting, rDNA internally transcribed spacer (ITS) region, and hrp b6 gene sequencing. Multiplication of onion Xanthomonas strain R-O177 was not different from X. axonopodis pv. phaseoli in dry bean, but typical common bacterial blight disease symptoms were absent in dry bean. Populations from each geographical region were uniformly sensitive to 100 mug of CuSO(4), 100 mug of ZnSO(4), and 100 mug of streptomycin sulfate per ml. Biolog substrate utilization and fatty acid profiles revealed close phenoltypic relatedness between onion strains of Xanthomonas and X. axonopodis pv. dieffenbachiae (57% of strains) and X. arboricola pv. poinsettiicola (37% of strains), respectively. A logistic regression model based on fatty acid composition and substrate utilization classified 69% of strains into their geographical region of origin. Sequencing of a portion of the hrp B6 gene from 24 strains and ITS region from 25 strains revealed greater than 97% sequence similarity among strains. DNA fingerprinting revealed five genotype groups within onion strains of Xanthomonas and a high degree of genetic diversity among geographical regions of origin. Based on pathogenicity to onion, carbon substrate utilization, fatty acid profiles, rDNA genetic diversity, and genomic fingerprints, we conclude that the strains examined in this study are pathovar X. axonopodis pv. allii. Implications of genetic and phenotypic diversity within X. axonopodis pv. allii are

  14. AN ORGANOTYPIC UNIAXIAL STRAIN MODEL USING MICROFLUIDICS

    PubMed Central

    Dollé, Jean-Pierre; Morrison, Barclay; Schloss, Rene R.; Yarmush, Martin L.

    2012-01-01

    Traumatic brain injuries are the leading cause of disability each year in the US. The most common and devastating consequence is the stretching of axons caused by shear deformation that occurs during rotational acceleration of the brain during injury. The injury effects on axonal molecular and functional events are not fully characterized. We have developed a strain injury model that maintains the three dimensional cell architecture and neuronal networks found in vivo with the ability to visualize individual axons and their response to a mechanical injury. The advantage of this model is that it can apply uniaxial strains to axons that make functional connections between two organotypic slices and injury responses can be observed in real-time and over long term. This uniaxial strain model was designed to be capable of applying an array of mechanical strains at various rates of strain, thus replicating a range of modes of axonal injury. Long term culture, preservation of slice and cell orientation, and slice-slice connection on the device was demonstrated. The device has the ability to strain either individual axons or bundles of axons through the control of microchannel dimensions. The fidelity of the model was verified by observing characteristic responses to various strain injuries which included axonal beading, delayed elastic effects and breakdown in microtubules. Microtubule breakdown was shown to be dependent on the degree of the applied strain field, where maximal breakdown was observed at peak strain and minimal breakdown is observed at low strain. This strain injury model could be a powerful tool in assessing strain injury effects on functional axonal connections. PMID:23233120

  15. Investigation of a noncontact strain measurement technique

    SciTech Connect

    Damiano, B.; Talarico, L.J.

    1996-05-01

    The goal of this project was to investigate the feasibility of a new noncontact technique for directly and continuously monitoring peak strain in rotating components. The technique utilizes the unique strain-sensitive magnetic material properties of transformation Induced Plasticity (TRIP) steel alloys to measure strain. These alloys are weakly magnetic when unstrained but become strongly ferromagnetic after mechanical deformation. A computer study was performed to determine whether the strain-induced change in the magnetic material properties of a TRIP steel gage bonded to a rotating component would cause significant perturbations in the magnetic flux of a stationary electromagnet. The effects of strain level, distance between the rotating component and the stationary electromagnet, and motion-induced eddy currents on flux perturbation magnitude were investigated. The calculated results indicate that a TRIP steel strain sensing element can cause a significant perturbation in the magnetic flux of a stationary electromagnet. The magnetic flux perturbation magnitude was found to be inversely proportional to the distance between the magnet face and the TRIP steel element and directly proportional to the TRIP steel strain level. The effect of motion-induced eddy currents on the magnetic flux was found to be negligible. It appears that the technique can be successfully applied to measure peak strain in rotating components; however, the sensitivity of the magnetic flux perturbation magnitude to the distance between the strain sensing element and the electromagnet may require making an independent proximity measurement.

  16. Measurement of Sorption-Induced Strain

    SciTech Connect

    Eric P. Robertson; Richard L. Christiansen

    2005-05-01

    Strain caused by the adsorption of gases was measured in samples of subbituminous coal from the Powder River basin of Wyoming, U.S.A. and high-volatile bituminous coal from east-central Utah, U.S.A. using an apparatus developed jointly at the Idaho National Laboratory (Idaho Falls, Idaho, U.S.A.) and Colorado School of Mines (Golden, Colorado, U.S.A.). The apparatus can be used to measure strain on multiple small coal samples based on the optical detection of the longitudinal strain instead of the more common usage of strain gauges, which require larger samples and longer equilibration times. With this apparatus, we showed that the swelling and shrinkage processes were reversible and that accurate strain data could be obtained in a shortened amount of time. A suite of strain curves was generated for these coals using gases that included carbon dioxide, nitrogen, methane, helium, and various mixtures of these gases. A Langmuir-type equation was applied to satisfactorily model the strain data obtained for pure gases. The sorption-induced strain measured in the subbituminous coal was larger than the high-volatile bituminous coal for all gases tested over the range of pressures used in the experimentation, with the CO2-induced strain for the subbituminous coal over twice as great at the bituminous coal.

  17. Lattice Strain Due to an Atomic Vacancy

    PubMed Central

    Li, Shidong; Sellers, Michael S.; Basaran, Cemal; Schultz, Andrew J.; Kofke, David A.

    2009-01-01

    Volumetric strain can be divided into two parts: strain due to bond distance change and strain due to vacancy sources and sinks. In this paper, efforts are focused on studying the atomic lattice strain due to a vacancy in an FCC metal lattice with molecular dynamics simulation (MDS). The result has been compared with that from a continuum mechanics method. It is shown that using a continuum mechanics approach yields constitutive results similar to the ones obtained based purely on molecular dynamics considerations. PMID:19582230

  18. High strain rate damage of Carrara marble

    NASA Astrophysics Data System (ADS)

    Doan, Mai-Linh; Billi, Andrea

    2011-10-01

    Several cases of rock pulverization have been observed along major active faults in granite and other crystalline rocks. They have been interpreted as due to coseismic pervasive microfracturing. In contrast, little is known about pulverization in carbonates. With the aim of understanding carbonate pulverization, we investigate the high strain rate (c. 100 s-1) behavior of unconfined Carrara marble through a set of experiments with a Split Hopkinson Pressure Bar. Three final states were observed: (1) at low strain, the sample is kept intact, without apparent macrofractures; (2) failure is localized along a few fractures once stress is larger than 100 MPa, corresponding to a strain of 0.65%; (3) above 1.3% strain, the sample is pulverized. Contrary to granite, the transition to pulverization is controlled by strain rather than strain rate. Yet, at low strain rate, a sample from the same marble displayed only a few fractures. This suggests that the experiments were done above the strain rate transition to pulverization. Marble seems easier to pulverize than granite. This creates a paradox: finely pulverized rocks should be prevalent along any high strain zone near faults through carbonates, but this is not what is observed. A few alternatives are proposed to solve this paradox.

  19. Optical fiber sensor technique for strain measurement

    DOEpatents

    Butler, Michael A.; Ginley, David S.

    1989-01-01

    Laser light from a common source is split and conveyed through two similar optical fibers and emitted at their respective ends to form an interference pattern, one of the optical fibers having a portion thereof subjected to a strain. Changes in the strain cause changes in the optical path length of the strain fiber, and generate corresponding changes in the interference pattern. The interference pattern is received and transduced into signals representative of fringe shifts corresponding to changes in the strain experienced by the strained one of the optical fibers. These signals are then processed to evaluate strain as a function of time, typical examples of the application of the apparatus including electrodeposition of a metallic film on a conductive surface provided on the outside of the optical fiber being strained, so that strains generated in the optical fiber during the course of the electrodeposition are measurable as a function of time. In one aspect of the invention, signals relating to the fringe shift are stored for subsequent processing and analysis, whereas in another aspect of the invention the signals are processed for real-time display of the strain changes under study.

  20. Diversity among Streptomyces Strains Causing Potato Scab

    PubMed Central

    Doering-Saad, Christiane; Kämpfer, Peter; Manulis, Shulamit; Kritzman, Giora; Schneider, Jörg; Zakrzewska-Czerwinska, Jolanta; Schrempf, Hildgund; Barash, Isaac

    1992-01-01

    Eighty Streptomyces isolates, including 35 potato scab-inducing strains and 12 reference strains of Streptomyces scabies, were physiologically characterized by a total of 329 miniaturized tests. Overall similarities of all strains were determined by numerical taxonomy, with the unweighted average linkage (UPGMA) algorithm and simple matching (Ssm) and Jaccard (Sj) coefficients used as measures for similarity. Three cluster groups (A to C) were defined at a similarity level of 80.1% (Ssm); these groups contained 14 clusters and 24 unclustered strains defined at a similarity level of 86.5% (Ssm). Cluster group A contained strains phenotypically related to S. griseus or S. exfoliatus, whereas cluster group B contained strains which were phenotypically related to S. violaceus or S. rochei. The majority of the pathogenic isolates and reference strains were assigned to S. violaceus (57%) and S. griseus (22%). A DNA probe derived from the rRNA operon of S. coelicolor IMET 40271 was used to detect restriction fragment length polymorphisms (RELPs) among 40 pathogenic and nonpathogenic Streptomyces isolates. Southern blots revealed a high degree of diversity among the pathogenic strains tested. No significant correlation between numerical classification and RFLP grouping of Streptomyces strains could be revealed. The results obtained suggest that RFLP data are of minor importance in classification of Streptomyces species and that genes for pathogenicity determinants are spread among different Streptomyces species by mobilizable elements. Images PMID:16348823

  1. Distributed strain monitoring for bridges: temperature effects

    NASA Astrophysics Data System (ADS)

    Regier, Ryan; Hoult, Neil A.

    2014-03-01

    To better manage infrastructure assets as they reach the end of their service lives, quantitative data is required to better assess structural behavior and allow for more informed decision making. Distributed fiber optic strain sensors are one sensing technology that could provide comprehensive data for use in structural assessments as these systems potentially allow for strain to be measured with the same accuracy and gage lengths as conventional strain sensors. However, as with many sensor technologies, temperature can play an important role in terms of both the structure's and sensor's performance. To investigate this issue a fiber optic distributed strain sensor system was installed on a section of a two span reinforced concrete bridge on the TransCanada Highway. Strain data was acquired several times a day as well as over the course of several months to explore the effects of changing temperature on the data. The results show that the strain measurements are affected by the bridge behavior as a whole. The strain measurements due to temperature are compared to strain measurements that were taken during a load test on the bridge. The results show that even a small change in temperature can produce crack width and strain changes similar to those due to a fully loaded transport truck. Future directions for research in this area are outlined.

  2. Strain induced fragility transition in metallic glass

    PubMed Central

    Yu, Hai-Bin; Richert, Ranko; Maaß, Robert; Samwer, Konrad

    2015-01-01

    Relaxation dynamics are the central topic in glassy physics. Recently, there is an emerging view that mechanical strain plays a similar role as temperature in altering the relaxation dynamics. Here, we report that mechanical strain in a model metallic glass modulates the relaxation dynamics in unexpected ways. We find that a large strain amplitude makes a fragile liquid become stronger, reduces dynamical heterogeneity at the glass transition and broadens the loss spectra asymmetrically, in addition to speeding up the relaxation dynamics. These findings demonstrate the distinctive roles of strain compared with temperature on the relaxation dynamics and indicate that dynamical heterogeneity inherently relates to the fragility of glass-forming materials. PMID:25981888

  3. Predictions Of Fatigue Damage From Strain Histories

    NASA Technical Reports Server (NTRS)

    Sire, Robert A.; Besuner, Philip M.; Toomey, Tim

    1989-01-01

    Semiempirical mathematical model of fatigue damage in stressed objects uses experimental histories of strains in those objects to predict fatigue lives. Accounts for initiation and propagation of fatigue cracks on cycle-by-cycle basis. Measured strain history first digitized, then converted to history of turning-point strains for purposes of analysis. Data between turning points not used. When model calibrated against proper test data for each type of object characterized, its predictions of fatigue lives superior to statistical models as one based on root-mean-square strain.

  4. Strain accommodation in inelastic deformation of glasses

    NASA Astrophysics Data System (ADS)

    Murali, P.; Ramamurty, U.; Shenoy, Vijay B.

    2007-01-01

    Motivated by recent experiments on metallic glasses, we examine the micromechanisms of strain accommodation including crystallization and void formation during inelastic deformation of glasses by employing molecular statics simulations. Our atomistic simulations with Lennard-Jones-like potentials suggests that a softer short range interaction between atoms favors crystallization. Compressive hydrostatic strain in the presence of a shear strain promotes crystallization whereas a tensile hydrostatic strain is found to induce voids. The deformation subsequent to the onset of crystallization includes partial reamorphization and recrystallization, suggesting important atomistic mechanisms of plastic dissipation in glasses.

  5. Inflatable device for installing strain gage bridges

    NASA Technical Reports Server (NTRS)

    Cook, C. E.; Smith, G. E.; Monaghan, R. C. (Inventor)

    1983-01-01

    Methods and devices for installing in a tubular shaft multiple strain gages are disclosed with focus on a method and a device for pneumatically forcing strain gages into seated engagement with the internal surfaces of a tubular shaft in an installation of multiple strain gages in a tubular shaft. The strain gages or other electron devices are seated in a template-like component which is wrapped about a pneumatically expansible body. The component is inserted into a shaft and the body is pneumatically expanded after a suitable adhesive was applied to the surfaces.

  6. Acceleration and Velocity Sensing from Measured Strain

    NASA Technical Reports Server (NTRS)

    Pak, Chan-Gi; Truax, Roger

    2016-01-01

    A simple approach for computing acceleration and velocity of a structure from the strain is proposed in this study. First, deflection and slope of the structure are computed from the strain using a two-step theory. Frequencies of the structure are computed from the time histories of strain using a parameter estimation technique together with an Autoregressive Moving Average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. shape sensing, fiber optic strain sensor, system equivalent reduction and expansion process.

  7. True stress-strain curves of cold worked stainless steel over a large range of strains

    NASA Astrophysics Data System (ADS)

    Kamaya, Masayuki; Kawakubo, Masahiro

    2014-08-01

    True stress-strain curves for cold worked stainless steel were obtained over a range of strains that included a large strain exceeding the strain for the tensile strength (post-necking strain). A specified testing method was used to obtain the stress-strain curves in air at room temperature. The testing method employed the digital image correlation (DIC) technique and iterative finite element analyses (FEA) and was referred to as IFD (Iteration FEA procedure based on DIC measurement) method. Although hourglass type specimens have been previously used for the IFD method, in this study, plate specimens with a parallel gage section were used to obtain accurate yield and tensile strengths together with the stress-strain curves. The stress-strain curves including the post-necking strain were successfully obtained by the IFD method, and it was shown that the stress-strain curves for different degrees of cold work collapsed onto a single curve when the offset strain was considered. It was also shown that the Swift type constitutive equation gave good regression for the true stress-strain curves including the post-necking strain regardless of the degree of cold work, although the Ramberg-Osgood type constitutive equation showed poor fit. In the regression for the Swift type constitutive equation, the constant for power law could be assumed to be nS = 0.5.

  8. Strain Rate Dependency of Coarse Crystal Marble Under Uniaxial Compression: Strength, Deformation and Strain Energy

    NASA Astrophysics Data System (ADS)

    Li, Yanrong; Huang, Da; Li, Xi'an

    2014-07-01

    Strain rate during testing, uniaxial or triaxial, has important influence on the measured mechanical properties of rocks. Uniaxial compression tests were performed at nine pre-specified static-to-quasistatic strain rates (ranging from 1 × 10-5 to 1 × 10-1 s-1) on coarse crystal marble. The aim is to gain deep insight into the influence of strain rate on characteristic stresses, deformation properties and conversion of strain energy of such rock. It is found that the strain rate of 5 × 10-3 s-1 is the threshold to delineate the failure modes the tested coarse marble behaves in. At a strain rate less than this threshold, single-plane shear and conjugate X-shaped shear are the main failure modes, while beyond this threshold, extensile and splitting failures are dominant. The stress for crack initiation, the critical stress for dilation, the peak stress, and Young's modulus are all found to increase with strain rate, with an exception that the above stresses and modulus appear relatively low compared to the strain rate in the range of between 1 × 10-4 and 5 × 10-3 s-1. The pre-peak absorbed strain energy, damage strain energy and elastic strain energy are found to increase with strain rate. In addition, the elastic strain energy stored before peak point favors brittle failure of the specimen, as the more stored elastic energy in the specimen, the stronger the fragmenting.

  9. Conduction band structure and electron mobility in uniaxially strained Si via externally applied strain in nanomembranes

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Euaruksakul, Chanan; Liu, Zheng; Himpsel, F. J.; Liu, Feng; Lagally, Max G.

    2011-08-01

    Strain changes the band structure of semiconductors. We use x-ray absorption spectroscopy to study the change in the density of conduction band (CB) states when silicon is uniaxially strained along the [1 0 0] and [1 1 0] directions. High stress can be applied to silicon nanomembranes, because their thinness allows high levels of strain without fracture. Strain-induced changes in both the sixfold degenerate Δ valleys and the eightfold degenerate L valleys are determined quantitatively. The uniaxial deformation potentials of both Δ and L valleys are directly extracted using a strain tensor appropriate to the boundary conditions, i.e., confinement in the plane in the direction orthogonal to the straining direction, which correspond to those of strained CMOS in commercial applications. The experimentally determined deformation potentials match the theoretical predictions well. We predict electron mobility enhancement created by strain-induced CB modifications.

  10. A comparison of eastern North American seismic strain-rates to glacial rebound strain-rates

    NASA Technical Reports Server (NTRS)

    James, Thomas S.; Bent, Allison L.

    1994-01-01

    Glacial rebound strain-rates computed using a simple Laurentide glacial loading model are of the order of 10(exp -9) per year within the region of glaciation and extending several hundred kilometers beyond. The horizontal strain-rates receive approximately equal contributions from horizontal and vertical velocities, a consequence of the spherical geometry adopted for the Earth model. In the eastern United States and southeastern Canada the computed strain-rates are 1-3 orders of magnitude greater than an estimate of the average seismic strain-rate (Anderson, 1986) and approximately 1 order of magnitude greater than predicted erosional strain-rates. The predicted glacial rebound strain-rates are not, in general, oriented in such a way as to augment the observed state of deviatoric stress, possibly explaining why the seismic strain-rates are much smaller than the glacial rebound strain-rates. An exception to this may be seismically active regions in the St. Lawrence valley.

  11. The Stress-Strain Condition Estimation of Detail in Crack Tip by Integral Strain Gauges

    NASA Astrophysics Data System (ADS)

    Syzrantsev, V.; Syzrantseva, K.

    2016-04-01

    The paper considers the task of stress-strain condition calculation of experimental sample in fatigue crack tip on weld boundary at its cyclic deforming. For this task decision authors use the information obtained by original means of cyclic strains measurement: Integral Strain Gauges. The results of carried experimental researches are compared with data of stress-strain condition estimation of detail in crack tip calculated by Finish Element Method.

  12. General Strain Theory and Delinquency: Focusing on the Influences of Key Strain Characteristics on Delinquency

    ERIC Educational Resources Information Center

    Moon, Byongook; Blurton, David; McCluskey, John D.

    2008-01-01

    The study examines the effects of recent, older, and chronic strains and of perceived injustice of strain on delinquency, sampling 777 Korean youth. Seven key strains most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…

  13. Differentiation of Lactobacillus strains by ribotyping.

    PubMed Central

    Rodtong, S; Tannock, G W

    1993-01-01

    Fifty-four lactobacillus strains were differentiated by ribotyping. The stability of ribotypes characteristic of four strains of lactobacilli inhabiting the digestive tract of mice was investigated. One of four isolates of Lactobacillus delbrueckii GT21, which had been associated with mice for 22 months, had an altered ribotype. Images PMID:7504432

  14. Strain engineering in graphene by laser irradiation

    SciTech Connect

    Papasimakis, N.; Mailis, S.; Huang, C. C.; Al-Saab, F.; Hewak, D. W.; Luo, Z.; Shen, Z. X.

    2015-02-09

    We demonstrate that the Raman spectrum of graphene on lithium niobate can be controlled locally by continuous exposure to laser irradiation. We interpret our results in terms of changes to doping and mechanical strain and show that our observations are consistent with light-induced gradual strain relaxation in the graphene layer.

  15. Fiscal Strain in an Era of Retrenchment.

    ERIC Educational Resources Information Center

    Hentschke, Guilbert; Yagielski, John

    Preliminary results of a three-year study of fifteen school districts indicate that fiscal strain results from both "intended" and "unintended" factors. The authors construct a model of fiscal strain that combines budget constraints with school district decision-makers' preference functions and indifference curves. Using this model and 1976 and…

  16. High-Temperature Resistance Strain Gauges

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen

    1994-01-01

    Resistance strain gauges developed for use at high temperatures in demanding applications like testing aircraft engines and structures. Measures static strains at temperatures up to 800 degrees C. Small and highly reproducible. Readings corrected for temperature within small tolerances, provided temperatures measured simultaneously by thermocouples or other suitable devices. Connected in wheatstone bridge.

  17. Marital Role Strain and Sexual Satisfaction.

    ERIC Educational Resources Information Center

    Frank, Ellen; And Others

    1979-01-01

    Responses to a questionnaire pertaining to discrepancies between an individual's ideal and actual marital role behaviors and level of sexual satisfaction indicated lower levels of role strain in nonpatient couples. A higher level of role strain correlated with increased sexual dissatisfaction. (Author)

  18. Genome Annotation of Five Mycoplasma canis Strains

    PubMed Central

    May, M.; Michaels, D. L.; Barbet, A. F.

    2012-01-01

    To understand its potential to cause invasive disease, the genome of Mycoplasma canis strain PG14T from a dog's throat was compared to those of isolates from the genital tract or brain of dogs. The average nucleotide identity between strain pairs is 98%, and their genome annotations are similar. PMID:22815452

  19. Surfactin production by strains of Bacillus mojavensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacillus mojavensis, RRC101 is an endophytic bacterium patented for control of fungal diseases in maize and other plants. DNA fingerprint analysis of the rep-PCR fragments of 35 B. mojavensis and 4 B. subtilis strains using the Diversilab genotyping system revealed genotypic distinctive strains alon...

  20. Medically Complex Home Care and Caregiver Strain

    ERIC Educational Resources Information Center

    Moorman, Sara M.; Macdonald, Cameron

    2013-01-01

    Purpose of the study: To examine (a) whether the content of caregiving tasks (i.e., nursing vs. personal care) contributes to variation in caregivers' strain and (b) whether the level of complexity of nursing tasks contributes to variation in strain among caregivers providing help with such tasks. Design and methods: The data came from the Cash…

  1. Silicon stress/strain activities at JPL

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    1986-01-01

    In-house Jet Propulsion Laboratory (JPL) work is described for silicon stress/strain, including the study of fracture mechanics, and on the high-temperature test program in which the low-strain response of silicon sheet materials above 1000 C is being measured and high temperature material property data are being determined.

  2. Nanocomposite Strain Gauges Having Small TCRs

    NASA Technical Reports Server (NTRS)

    Gregory, Otto; Chen, Ximing

    2009-01-01

    Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

  3. High strain rate behavior of polyurea compositions

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant S.; Milby, Christopher

    2012-03-01

    High-strain-rate response of three polyurea compositions with varying molecular weights has been investigated using a Split Hopkinson Pressure Bar arrangement equipped with aluminum bars. Three polyurea compositions were synthesized from polyamines (Versalink, Air Products) with a multi-functional isocyanate (Isonate 143L, Dow Chemical). Amines with molecular weights of 1000, 650, and a blend of 250/1000 have been used in the current investigation. These materials have been tested to strain rates of over 6000/s. High strain rate results from these tests have shown varying trends as a function of increasing strain. While higher molecular weight composition show lower yield, they do not show dominant hardening behavior at lower strain. On the other hand, the blend of 250/1000 show higher load bearing capability but lower strain hardening effects than the 600 and 1000 molecular weight amine based materials. Results indicate that the initial increase in the modulus of the blend of 250/1000 may lead to the loss of strain hardening characteristics as the material is compressed to 50% strain, compared to 1000 molecular weight amine based material.

  4. Whole genome sequences of four Brucella strains.

    PubMed

    Ding, Jiabo; Pan, Yuanlong; Jiang, Hai; Cheng, Junsheng; Liu, Taotao; Qin, Nan; Yang, Yi; Cui, Buyun; Chen, Chen; Liu, Cuihua; Mao, Kairong; Zhu, Baoli

    2011-07-01

    Brucella melitensis and Brucella suis are intracellular pathogens of livestock and humans. Here we report four genome sequences, those of the virulent strain B. melitensis M28-12 and vaccine strains B. melitensis M5 and M111 and B. suis S2, which show different virulences and pathogenicities, which will help to design a more effective brucellosis vaccine. PMID:21602346

  5. Bicrystals with strain gradient effects

    SciTech Connect

    Shu, J.Y.

    1997-01-09

    Boundary between two perfectly bonded single crystals plays an important role in determining the deformation of the bicrystals. This work addresses the role of the grain boundary by considering the elevated hardening of a slip system due to a slip gradient. The slip gradients are associated with geometrically necessary dislocations and their effects become pronounced when a representative length scale of the deformation field is comparable to the dominant microstructural length scale of a material. A new rate-dependent crystal plasticity theory is presented and has been implemented within the finite element method framework. A planar bicrystal under uniform in-plane loading is studied using the new crystal theory. The strain is found to be continuous but nonuniform within a boundary layer around the interface. The lattice rotation is also nonuniform within the boundary layer. The width of the layer is determined by the misorientation of the grains, the hardening of slip systems, and most importantly by the characteristic material length scales. The overall yield strength of the bicrystal is also obtained. A significant grain-size dependence of the yield strength, the Hall- Petch effect is predicted.

  6. New naphthalene-degrading marine Pseudomonas strains.

    PubMed Central

    García-Valdés, E; Cozar, E; Rotger, R; Lalucat, J; Ursing, J

    1988-01-01

    Over 100 strains that utilized naphthalene as the only carbon and energy source were isolated from samples of marine sediments taken from a heavily polluted area. The isolates were characterized taxonomically and physiologically. Most of these strains belonged to the genus Pseudomonas, and seven of them did not fit any previous taxonomic description. They differed from type strains in a few biochemical characteristics and in the utilization of aromatic compounds. None had catechol 1,2-dioxygenase activity, and catechol 2,3-dioxygenase was responsible for the aromatic ring cleavage. DNA hybridization demonstrated a close relationship between two isolates and the Pseudomonas stutzeri type strain, and between five isolates and the Pseudomonas testosteroni type strain. On the basis of nutritional and enzymatic characteristics, it was assumed that the seven isolates represent new biovars belonging to the species P. testosteroni and P. stutzeri that are able to degrade aromatic hydrocarbons. Images PMID:3202629

  7. Mechanical strain effects on black phosphorus nanoresonators.

    PubMed

    Wang, Cui-Xia; Zhang, Chao; Jiang, Jin-Wu; Park, Harold S; Rabczuk, Timon

    2016-01-14

    We perform classical molecular dynamics simulations to investigate the effects of mechanical strain on single-layer black phosphorus nanoresonators at different temperatures. We find that the resonant frequency is highly anisotropic in black phosphorus due to its intrinsic puckered configuration, and that the quality factor in the armchair direction is higher than in the zigzag direction at room temperature. The quality factors are also found to be intrinsically larger than those in graphene and MoS2 nanoresonators. The quality factors can be increased by more than a factor of two by applying tensile strain, with uniaxial strain in the armchair direction being the most effective. However, there is an upper bound for the quality factor increase due to nonlinear effects at large strains, after which the quality factor decreases. The tension induced nonlinear effect is stronger along the zigzag direction, resulting in a smaller maximum strain for quality factor enhancement. PMID:26649476

  8. Nanoscale strain mapping in battery nanostructures

    SciTech Connect

    Ulvestad, A. Kim, J. W.; Dietze, S. H.; Shpyrko, O. G.; Cho, H. M.; Meng, Y. S.; Harder, R.; Fohtung, E.

    2014-02-17

    Coherent x-ray diffraction imaging is used to map the local three dimensional strain inhomogeneity and electron density distribution of two individual LiNi{sub 0.5}Mn{sub 1.5}O{sub 4−δ} cathode nanoparticles in both ex-situ and in-situ environments. Our reconstructed images revealed a maximum strain of 0.4%. We observed different variations in strain inhomogeneity due to multiple competing effects. The compressive/tensile component of the strain is connected to the local lithium content and, on the surface, interpreted in terms of a local Jahn-Teller distortion of Mn{sup 3+}. Finally, the measured strain distributions are discussed in terms of their impact on competing theoretical models of the lithiation process.

  9. New naphthalene-degrading marine Pseudomonas strains

    SciTech Connect

    Garcia-Valdes, E.; Cozar, E.; Rotger, R. Lalucat, J. ); Ursing, J. )

    1988-10-01

    Over 100 strains that utilized naphthalene as the only carbon and energy source were isolated from samples of marine sediments taken from a heavily polluted area. The isolates were characterized taxonomically and physiologically. Most of these strains belonged to the genus Pseudomonas, and seven of them did not fit any previous taxonomic description. They differed from type strains in a few biochemical characteristics and in the utilization of aromatic compounds. None had catechol 1,2-dioxygenase activity, and catechol 2,3-dioxygenase was responsible for the aromatic ring cleavage. DNA hybridizations demonstrated a close relationship between two isolates and the Pseudomonas stutzeri type strain, and between five isolates and the Pseudomonas testosteroni type strain. On the basis of nutritional and enzymatic characteristics, it was assumed that the seven isolates represent new biovars belonging to the species P. testosteroni and P. stutzeri that are able to degrade aromatic hydrocarbons.

  10. Micro-scale strain mapping technique: a tool to quantify strain partitioning during creep deformation

    NASA Astrophysics Data System (ADS)

    Quintanilla-Terminel, Alejandra; Zimmerman, Mark; Evans, Brian; Kohlstedt, David

    2016-04-01

    Several deformation mechanisms interact to accommodate plastic deformation. Quantifying the contribution of each to the total strain is necessary for establishing a better link between observed microstructures and mechanical data, as well as to allow more confident extrapolation from laboratory to natural conditions. In this contribution, we present the experimental and computational technique involved in micro-scale strain mapping (MSSM). The MSSM technique relies on analyzing the relative displacement of initially regularly spaced markers after deformation. We present several microfabrication techniques that permit us to pattern various rocks with micrometric and nanometric metal markers, as well as the challenges faced in working at high temperatures and pressures. A Hough transform algorithm was used to detect the markers and automate as much as possible the strain analysis. The von Mises strain is calculated for a set of n-points and their relative displacements, which allow us to map the strain at different length scales. We applied the MSSM technique to study strain partitioning during deformation creep of Carrara marble and San Carlos olivine at a confining pressure, Pc, of 300 MPa and homologous temperatures of 0.3 to 0.6. We measured the local strain and strain heterogeneity produced during creep deformation of split cylinders of Carrara marble under conventional triaxial loading to inelastic strains of 11 to 36% at a strain rate of 3x10‑5s‑1, Pc = 300 MPa and 400o < T <700oC. We conclude that the evolution of deformation structures in marble takes place over a substantial interval in strain and that the duration of this interval depends on strain rate, temperature, and pressure. Our first results on strain mapping of olivine deformed at T = 1150oC and Pc = 300 MPa demonstrate promise for characterizing intragranular strain and better defining the contribution of grain boundary sliding to the total strain.