bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbohydrate epitopes are immunodominant at the surface of infectious Neoparamoeba spp.
Authors: Villavedra M , Lemke S , To J , Broady K , Wallach M , Raison R L 
Published: March 2007

AbstractAmoebic gill disease, the main disease of concern to the salmon industry in Tasmania, is caused by the amoeba, Neoparamoeba spp. Experimental infection can only be induced by exposure to wild‐type (WT) parasites isolated from the gills of infected fish, as cultured amoebae are non‐infective. To characterize the surface antigens of WT parasites, we produced monoclonal antibodies (mAbs) using subtractive immunization. Mice inoculated with non‐infective parasites were treated with cyclophosphamide, to deplete reactive lymphocytes, and then immunized with different antigen preparations from infective parasites. When whole parasites were used for boosting, the percentage of WT unique mAbs was very high (86%) as was the percentage of mAbs specific for carbohydrate epitopes (89%). When deglycosylated membranes were used, the numbers of mAbs specific for non‐carbohydrate epitopes did not increase, but the total number of WT unique mAbs was reduced (86–40%). Using an untreated membrane preparation, the total number of mAbs to surface molecules was very high, but all recognized carbohydrate epitopes. The total number of mAbs recognizing carbohydrate epitopes on the surface of the WT parasites was 97%, suggesting that the dominant epitopes on the surface molecules unique to WT parasites are carbohydrate in nature.
Isolation of viral haemorrhagic septicaemia virus from mummichog, stickleback, striped bass and brown trout in eastern Canada
Authors: Gagné N , MacKinnon A‐M , Boston L , Souter B , Cook‐Versloot M , Griffiths S , Olivier G 
Published: March 2007

AbstractViral haemorrhagic septicaemia virus (VHSV) was isolated from mortalities occurring in populations of mummichog, Fundulus heteroclitus, stickleback, Gasterosteus aculeatus aculeatus, brown trout, Salmo trutta, and striped bass, Morone saxatilis, in New Brunswick and Nova Scotia, Canada. The isolated viral strains produced a cytopathic effect on the epithelioma papillosum cyprini cell line. Serum neutralization indicated the virus was VHSV and sequencing identified the rhabdovirus isolates as the North American strain of VHSV. Phylogenetic analysis indicated that the isolates are closely related and form a distinguishable subgroup of North American type VHSV. To our knowledge, this is the first report of VHSV in mummichog and striped bass.
Evaluation of stress‐ and immune‐response biomarkers in Atlantic salmon, Salmo salar L., fed different levels of genetically modified maize (Bt maize), compared with its near‐isogenic parental line and a commercial suprex maize
Authors: Sagstad A , Sanden M , Haugland Ø , Hansen A‐C , Olsvik P A , Hemre G‐I 
Published: March 2007

AbstractThe present study was designed to evaluate if genetically modified (GM) maize (Bt maize, event MON810) compared with the near‐isogenic non‐modified (nGM) maize variety, added as a starch source at low or high inclusions, affected fish health of post‐smolt Atlantic salmon, Salmo salar L. To evaluate the health impact, selected stress‐ and immune‐response biomarkers were quantified at the gene transcript (mRNA) level, and some also at the protein level. The diets with low or high inclusions of GM maize, and its near‐isogenic nGM parental line, were compared to a control diet containing GM‐free suprex maize (reference diet) as the only starch source. Total superoxide dismutase (SOD) activity in liver and distal intestine was significantly higher in fish fed GM maize compared with fish fed nGM maize and with the reference diet group. Fish fed GM maize showed significantly lower catalase (CAT) activity in liver compared with fish fed nGM maize and to the reference diet group. In contrast, CAT activity in distal intestine was significantly higher for fish fed GM maize compared with fish fed reference diet. Protein level of heat shock protein 70 (HSP70) in liver was significantly higher in fish fed GM maize compared with fish fed the reference diet. No diet‐related differences were found in normalized gene expression of SOD, CAT or HSP70 in liver or distal intestine. Normalized gene expression of interleukin‐1 beta in spleen and head‐kidney did not vary significantly between diet groups. Interestingly, fish fed high GM maize showed a significantly larger proportion of plasma granulocytes, a significantly larger sum of plasma granulocyte and monocyte proportions, but a significantly smaller proportion of plasma lymphocytes, compared with fish fed high nGM maize. In conclusion, Atlantic salmon fed GM maize showed some small changes in stress protein levels and activities, but none of these changes were comparable to the normalized gene expression levels analysed for these stress proteins. GM maize seemed to induce significant changes in white blood cell populations which are associated with an immune response.
Lack of genetic structure among ecologically adapted populations of an Australian rainforest Drosophila species as indicated by microsatellite markers and mitochondrial DNA sequences
Authors: SCHIFFER MICHELE , KENNINGTON W. J. , HOFFMANN A. A. , BLACKET M. J. 
Published: March 2007

AbstractAlthough fragmented rainforest environments represent hotspots for invertebrate biodiversity, few genetic studies have been conducted on rainforest invertebrates. Thus, it is not known if invertebrate species in rainforests are highly genetically fragmented, with the potential for populations to show divergent selection responses, or if there are low levels of gene flow sufficient to maintain genetic homogeneity among fragmented populations. Here we use microsatellite markers and DNA sequences from the mitochondrial ND5 locus to investigate genetic differences among Drosophila birchii populations from tropical rainforests in Queensland, Australia. As found in a previous study, mitochondrial DNA diversity was low with no evidence for population differentiation among rainforest fragments. The pattern of mitochondrial haplotype variation was consistent with D. birchii having undergone substantial past population growth. Levels of nuclear genetic variation were high in all populations while FST values were very low, even for flies from geographically isolated areas of rainforest. No significant differentiation was observed between populations on either side of the Burdekin Gap (a long‐term dry corridor), although there was evidence for higher gene diversity in low‐latitude populations. Spatial autocorrelation coefficients were low and did not differ significantly from random, except for one locus which revealed a clinal‐like pattern. Comparisons of microsatellite differentiation contrasted with previously established clinal patterns in quantitative traits in D. birchii, and indicate that the patterns in quantitative traits are likely to be due to selection. These results suggest moderate gene flow in D. birchii over large distances. Limited population structure in this species appears to be due to recent range expansions or cycles of local extinctions followed by recolonizations/expansions. Nevertheless, patterns of local adaptation have developed in D. birchii that may result in populations showing different selection responses when faced with environmental change.
The geography of diversification in mutualistic ants: a gene's‐eye view into the Neogene history of Sundaland rain forests
Authors: QUEK S.‐P. , DAVIES S. J. , ASHTON P. S. , ITINO T. , PIERCE N. E. 
Published: March 2007

AbstractWe investigate the geographical and historical context of diversification in a complex of mutualisticCrematogasterants living inMacarangatrees in the equatorial rain forests of Southeast Asia. Using mitochondrial DNA from 433 ant colonies collected from 32 locations spanning Borneo, Malaya and Sumatra, we infer branching relationships, patterns of genetic diversity and population history. We reconstruct a time frame for the ants’ diversification and demographic expansions, and identify areas that might have been refugia or centres of diversification. Seventeen operational lineages are identified, most of which can be distinguished by host preference and geographical range. The ants first diversified 16–20 Ma, not long after the onset of the everwet forests in Sundaland, and achieved most of their taxonomic diversity during the Pliocene. Pleistocene demographic expansions are inferred for several of the younger lineages. Phylogenetic relationships suggest a Bornean cradle and major axis of diversification. Taxonomic diversity tends to be associated with mountain ranges; in Borneo, it is greatest in the Crocker Range of Sabah and concentrated also in other parts of the northern northwest coast. Within‐lineage genetic diversity in Malaya and Sumatra tends to also coincide with mountain ranges. A series of disjunct and restricted distributions spanning northern northwest Borneo and the major mountain ranges of Malaya and Sumatra, seen in three pairs of sister lineages, further suggests that these regions were rain‐forest refuges during drier climatic phases of the Pleistocene. Results are discussed in the context of the history of Sundaland's rain forests.
Astrometric observations of triton
Authors: Qiao R. C. , Yan Y. R. , Shen K. X. , Dourneau G. , Xi X. J. , Cheng X. , Wang S. H. , Tang Z. H. , Liu J. R. 
Published: March 2007

Abstract
Astrometric positions of the Neptunian Satellite Triton are given for the opposition of Neptune for the years 1996, 2003, 2005 and 2006. The 943 observed positions were obtained at the Cassegrain focus of a 156-cm reflector. In our reduction, the up-to-date catalogue of stars UCAC2 was chosen to ensure a proper astrometric calibration. Our observed positions are compared to theoretical positions provided from JPL and IMCCE ephemerides. The observed minus calculated residuals have s.d. values of the order of 0.04 arcsec.
Estimation of metabolic fluxes, expression levels and metabolite dynamics of a secondary metabolic pathway in potato using label pulse‐feeding experiments combined with kinetic network modelling and simulation
Authors: Heinzle Elmar , Matsuda Fumio , Miyagawa Hisashi , Wakasa Kyo , Nishioka Takaaki 
Published: March 2007

SummaryIn this paper we present a method that allows dynamic flux analysis without a priori kinetic knowledge. This method was developed and validated using the pulse‐feeding experimental data obtained in our previous study (Matsuda et al., 2005), in which incorporation of exogenously applied l‐phenylalanine‐d5 into seven phenylpropanoid metabolites in potato tubers was determined. After identification of the topology of the metabolic network of these biosynthetic pathways, the system was described by dynamic mass balances in combination with power‐law kinetics. After the first simulations, some reactions were removed from the network because they were not contributing significantly to network behaviour. As a next step, the exponents of the power‐law kinetics were identified and then kept at fixed values during further analysis. The model was tested for statistical reliability using Monte Carlo simulations. Most fluxes could be identified with high accuracy. The two test cases, control and after elicitation, were clearly distinguished, and with elicitation fluxes to N‐p‐coumaroyloctopamine (pCO) and N‐p‐coumaroyltyramine (pCT) increased significantly, whereas those for chlorogenic acid (CGA) and p‐coumaroylshikimate decreased significantly. According to the model, increases in the first two fluxes were caused by induction/derepression mechanisms. The decreases in the latter two fluxes were caused by decreased concentrations of their substrates, which in turn were caused by increased activity of the pCO‐ and pCT‐producing enzymes. Flux‐control analysis showed that, in most cases, flux control was changed after application of elicitor. Thus the results revealed potential targets for improving actions against tissue wounding and pathogen attack.
INFLUENCE OF MICROSTRUCTURE ON SHORT FATIGUE CRACK GROWTH
Authors: Plumtree A. , O'Connor B. P. D. 
Published: April 2007

AbstractThe influence of microstructure and processing method on the initiation and growth of fatigue cracks in an aluminum‐magnesium‐silicon alloy has been studied with extruded and squeeze‐cast material cycled in strain control. Using the replication technique, initiation and early growth of short cracks was found to be dependent upon the applied strain level. At low strains decohesion at the particle/matrix interface occurred whereas at high strain levels both particle cracking and decohesion were observed. The micromechanisms of subsequent short crack growth were also influenced by strain amplitude. In the case of the squeeze‐cast material cycled at low total strain amplitudes subsequent growth took place from particle to particle along the soft precipitate‐free interdendritic regions, in the direction of maximum shear. Notable deflection occurred at triple points. Short cracks in the extruded material cycled at all total strain amplitudes were found to initiate by debonding of particles in banded zones. Early crack growth at low strain amplitudes over the first 20μ along the surface was significantly impeded by subgrains and some second phase particles, whose effect was much greater than for the squeeze‐cast material due to a finer microstructure (the average subgrain size was 6 μ) and absence of soft interdendritic regions. The fracture surface was also rougher which presented a greater degree of resistance to propagation. In both types of material, Stage I crack growth extended to a depth of about 250‐350 μ. During this portion of life short fatigue crack growth behaviour was observed. Long crack behaviour coincided with the crack switching to Stage II growth. Short crack propagation behaviour and the crack depth at which Stage I was complete could be expressed using a crack growth model based on the strength of slip bands emanating from the crack tip and the strength of barriers which were in the immediate area.
Efficacy of intervention strategies for bioremediation of crude oil in marine systems and effects on indigenous hydrocarbonoclastic bacteria
Authors: McKew Boyd A. , Coulon Frédéric , Yakimov Michail M. , Denaro Renata , Genovese Maria , Smith Cindy J. , Osborn A. Mark , Timmis Kenneth N. , McGenity Terry J. 
Published: March 2007

SummaryThere is little information on how different strategies for the bioremediation of marine oil spills influence the key indigenous hydrocarbon‐degrading bacteria (hydrocarbonoclastic bacteria, HCB), and hence their remediation efficacy. Therefore, we have used quantitative polymerase chain reaction to analyse changes in concentrations of HCB in response to intervention strategies applied to experimental microcosms. Biostimulation with nutrients (N and P) produced no measurable increase in either biodegradation or concentration of HCB within the first 5 days, but after 15 days there was a significant increase (29%; P <  0.05) in degradation of n‐alkanes, and an increase of one order of magnitude in concentration of Thalassolituus (to 107 cells ml−1). Rhamnolipid bioemulsifier additions alone had little effect on biodegradation, but, in combination with nutrient additions, provoked a significant increase: 59% (P < 0.05) more n‐alkane degradation by 5 days than was achieved with nutrient additions alone. The very low Alcanivorax cell concentrations in the microcosms were hardly influenced by addition of nutrients or bioemulsifier, but strongly increased after their combined addition, reflecting the synergistic action of the two types of biostimulatory agents. Bioaugmentation with Thalassolituus positively influenced hydrocarbon degradation only during the initial 5 days and only of the n‐alkane fraction. Bioaugmentation with Alcanivorax was clearly much more effective, resulting in 73% greater degradation of n‐alkanes, 59% of branched alkanes, and 28% of polynuclear aromatic hydrocarbons, in the first 5 days than that obtained through nutrient addition alone (P < 0.01). Enhanced degradation due to augmentation with Alcanivorax continued throughout the 30‐day period of the experiment. In addition to providing insight into the factors limiting oil biodegradation over time, and the competition and synergism between HCB, these results add weight to the use of bioaugmentation in oil pollution mitigation strategies.
Interactions and competition within the microbial community of the human colon: links between diet and health
Authors: Flint Harry J. , Duncan Sylvia H. , Scott Karen P. , Louis Petra 
Published: March 2007

SummaryThe microbiota of the human intestinal tract play an important role in health, in particular by mediating many of the effects of diet upon gut health. Surveys of 16S rRNA sequence diversity in the human colon have emphasized the low proportion of sequences that match cultured bacterial species. This may reflect limited recent effort on cultivation rather than inherent unculturability, however, as anaerobic isolation methods can apparently recover a wide range of the diversity found. A combination of information from representative cultures, molecular tools for enumeration and tracking of bacterial metabolites offers the most powerful route to understanding the roles played by different groups of bacteria in the gut ecosystem. Progress is being made for example in defining key functional groups including primary colonizers of insoluble dietary substrates, and major contributors to metabolites such as butyrate that influence the health of the gut mucosa. There is increasing evidence that bacterial populations in the large intestine respond to changes in diet, in particular to the type and quantity of dietary carbohydrate. A general consequence of increased carbohydrate consumption is to reduce the pH of the gut lumen, which is likely to play a major role in determining bacterial metabolism and competition. Oligosaccharides used as dietary prebiotics must inevitably have complex effects upon the bacterial community that include non‐target organisms and the consequences of metabolic cross‐feeding and changes in the gut environment.
Temperature and pyoverdine‐mediated iron acquisition control surface motility of Pseudomonas putida
Authors: Matilla Miguel A. , Ramos Juan L. , Duque Estrella , de Dios Alché Juan , Espinosa‐Urgel Manuel , Ramos‐González María Isabel 
Published: March 2007

SummaryPseudomonas putida KT2440 is unable to swarm at its common temperature of growth in the laboratory (30°C) but exhibits surface motility similar to swarming patterns in other Pseudomonas between 18°C and 28°C. These motile cells show differentiation, consisting on elongation and the presence of surface appendages. Analysis of a collection of mutants to define the molecular determinants of this type of surface movement in KT2440 shows that while type IV pili and lipopolysaccharide O‐antigen are requisites flagella are not. Although surface motility of flagellar mutants was macroscopically undistinguishable from that of the wild type, microscopy analysis revealed that these mutants move using a distinct mechanism to that of the wild‐type strain. Mutants either in the siderophore pyoverdine (ppsD) or in the FpvA siderophore receptor were also unable to spread on surfaces. Motility in the ppsD strain was totally restored with pyoverdine and partially with the wild‐type ppsD allele. Phenotype of the fpvA strain was not complemented by this siderophore. We discuss that iron influences surface motility and that it can be an environmental cue for swarming‐like movement in P. putida. This study constitutes the first report assigning an important role to pyoverdine iron acquisition in en masse bacterial surface movement.
Bacteria associated with the rapid tissue necrosis of stony corals
Authors: Luna G. M. , Biavasco F. , Danovaro R. 
Published: March 2007

SummaryThe rapid tissue necrosis (RTN) is a common disease of both wild and captive stony corals, which causes a fast tissue degradation (peeling) and death of the colony. Here we report the results of an investigation carried out on the stony coral Pocillopora damicornis, affected by an RTN‐like disease. Total abundance of prokaryotes in tissue samples, determined by epifluorescence microscopy, was significantly higher in diseased than in healthy corals, as well as bacterial counts on MB2216 agar plates. Further experiments performed by fluorescent in situ hybridization using a 16S rDNA Vibrio‐specific probe showed that vibrios were significantly more abundant in diseased than in healthy corals. Accordingly, bacterial counts on TCBS agar plates were higher in diseased than in healthy tissues. 16S rDNA sequencing identified as Vibrio colonies from diseased tissues only. Cultivated vibrios were dominated by a single ribotype, which displayed 99% of similarity with Vibrio harveyi strain LB4. Bacterial ribotype richness, assessed by terminal‐restriction fragment length polymorphism analysis of the 16S rDNA, was significantly higher in diseased than in healthy corals. Using an in silico software, we estimated that a single terminal restriction fragment, putatively assigned to a Vibrio sp., accounted for > 15% and < 5% of the total bacterial assemblage, in diseased and healthy corals respectively. These results let us hypothesize that the RTN in stony corals can be an infectious disease associated to the presence of Vibrio harveyi. However, further studies are needed to validate the microbial origin of this pathology.
Models for the Valuation of International Convertible Bonds
Authors: Jennergren L. Peter , Näslund Bertil 
Published: April 2007

AbstractThis paper presents a family of three models for the valuation of international convertible bonds which are denominated in a currency different from that of the country of the issuing corporation. The first model is two‐state, with the value of the underlying stock and the value of the currency of the parent country as state variables. The second model is one‐state. It is derived from the first one, with the two state variables collapsed into one, listed share price times exchange rate. The third model is an extension of the second one, in that it includes the risk of devaluation of the currency of the country of the issuing corporation. One specific Euroconvertible bond, issued by the Swedish corporation SCA, is used as illustration throughout.
The Association Between the Level of International Diversification and Risk
Authors: Goldberg Stephen R. , Heflin Frank L. 
Published: April 2007

AbstractThis study analyzes the association between the degree of international involvement (DOI) and risk. Both systematic risk (measured by the market model beta) and total risk (measured by variance of return) are analyzed. Betas of fully diversified foreign stock portfolios are shown to be lower than betas of domestic portfolios. Therefore, if the beta of a foreign investment by a U.S. firm is equal to the average beta of an investment in the foreign market, then overall firm beta will decrease as DOI increases (hypothesis). While total risk might be decreased due to the diversification provided by increasing DOI, currency, political, and other risks could cause total risk to increase. Briefly, the results of this study suggest that (1) systematic risk is negatively related to DOI even after controlling for other factors known to be associated with systematic risk, (2) intertemporal changes in systematic risk are negatively related to intertemporal changes in DOI, and (3) in contrast to the results of previous research, DOI is not negatively related to total risk and, in fact, intertemporal changes in total firm risk are marginally positively related to intertemporal changes in DOI.Our results suggest that increasing DOI decreases systematic risk but increases total risk. Year to year changes in both beta and variance of return appear to be related to year to year changes in DOI. While currency, political, and other risks of international operations increase total risk, these risks apparently can be diversified away resulting in a beta that behaves as a blending of its previous level and the beta of a fully diversified investment in the foreign market.