bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular cloning and partial characterization of a nematode-specific 24 kDa protein fromAscaris suum
Authors: ISLAM M. K. , MIYOSHI T. , YOKOMIZO Y. , TSUJI N.
Published: December 2004

The cloning and molecular characterization of a cDNA encodingAscaris suum24 kDa antigen (As24) are described. The cDNA sequence consists of 853 bp with an open reading frame coding for a protein of 147 amino acids with an inferred signal peptide of 19 amino acids. The predicted molecular mass and pI were 16 kDa and 8·35 respectively. The endogenous protein in adultA. suumwas 24 kDa with the expected pI. A search of the public databases revealed over 50% homology with proteins from filarial parasites but not to other known proteins, suggesting that As24 is a nematode-specific protein. Immunohistochemical studies using polyclonal antibodies raised againstEscherichia coli-expressed recombinant As24 demonstrated that the endogenous As24 proteins were intensely localized in unembryonated eggs within the uterus, uterine and gut epithelium, muscle tissues and in the hypodermis of an adult femaleA. suum. Endogenous As24 was expressed throughoutA. suumdevelopment and was detected in the excretory/secretory products by immunoblot analysis. Importantly, a homologous protein(s) was detected inAscarisfrom human andToxocara canisfrom dog, suggesting that As24 is a nematode-specific protein.
Molecular analysis of astacin-like metalloproteases ofOstertagia ostertagi
Authors: DE MAERE V. , VERCAUTEREN I. , GELDHOF P. , GEVAERT K. , VERCRUYSSE J. , CLAEREBOUT E.
Published: December 2004

In this study, we describe the molecular analysis of zinc-metalloproteases from the abomasal nematodeOstertagia ostertagiwhich were exclusively recognized by local antibodies of immune cattle. Full-length or partial coding sequences of 4 different zinc-metalloprotease cDNAs ofOstertagia(met-1, -2, -3 and -4) were amplified using gene-specific primers using the 3′- and 5′-Rapid Amplification of cDNA Ends (RACE) technique. Sequence analysis identified the cDNAs as encoding zinc-metalloproteases, which showed between 62% and 70% homology to a metalloprotease 1 precursor ofAncylostoma caninum. The full-length cDNA ofmet-1consists of an open reading frame (ORF) of 586 amino acids which contains 5 potentialN-glycosylation sites and a predicted zinc-binding domain (HEBXHXBGFXHEXXRXDRD). The complete coding sequence ofmet-3contains an ORF of 508 aa and the same conserved zinc-binding domain. These domains are signature sequences of the astacin family of the superfamily of metzincin metalloproteases. The presence of a threonine amino acid after the third histidine in MET-1 and MET-3, however, may place them in a new family or subfamily. Real-time PCR analysis of L3, exsheathed L3, L4and adult cDNA identified transcription of the 4 metalloproteases in different life-stages. The protein MET-1 was expressed in insect cells using the baculovirus expression system but the immunization of calves with this molecule did not lead to protection against challenge infection.
Ultrastructural and molecular characterization of Bacillidium vesiculoformis n. sp. (Microspora: Mrazekiidae) in the freshwater oligochaete Nais simplex (Oligochaeta: Naididae)
Authors: MORRIS D. J. , TERRY R. S. , FERGUSON K. B. , SMITH J. E. , ADAMS A.
Published: December 2004

The development of a new species, Bacillidium vesiculoformis n. sp. (Microspora, Mrazekiidae), is described from the freshwater oligochaete Nais simplex (Oligochaeta, Naididae). Initial stages of parasite development consist of a monokaryotic merogony within a haemocyte of the intestinal blood sinus. The resulting hypertrophied haemocyte is attached to the chloragocytes of the sinus by fine cytoplasmic extensions with the sinus around the cell becoming greatly enlarged. The meronts within the haemocyte form diplokaryotic sporonts that undergo sporogenesis directly within the cytoplasm of the host cell. The infected cell becomes packed with spores and developmental stages, causing it dramatically to increase in size, eventually rupturing the oligochaete and cell. Sporogony appears to be disporoblastic. Released spores were observed to have an adhesive quality. Transmission studies conducted with mature spores failed to transmit the parasite horizontally although vertical transmission was observed. Phylogenetic analysis of the parasite demonstrated that B. vesiculoformis clustered with microsporidian parasites of bryozoa and two other microsporidians, Janacekia debaiseuxi and an unidentified Bacillidium sp.
Relative infection levels and taxonomic distances among the host species used by a parasite: insights into parasite specialization
Authors: POULIN R.
Published: December 2004

Parasites often exploit more than one host species at any stage in their life-cycle, but the extent to which these host species are used varies greatly. Parasites typically achieve their highest prevalence, intensity and/or abundance in one host species (the principal host), whereas infection levels in auxiliary hosts range from relatively high to very low. The present study examines what influences the distribution of parasite individuals among their different host species, using metazoan parasites that use freshwater fish as their definitive or only host. Specifically, I test the hypothesis that differences in relative infection levels by a parasite among its auxiliary hosts are proportional to the taxonomic distance between the respective auxiliary hosts and the parasite's principal host. Taxonomic distance among hosts is a surrogate measure of their similarity in terms of ecology, physiology and immunology. Using data on 29 parasite species and 6 fish communities, for a total of 47 parasite-locality combinations, it was found that taxonomic distance between the auxiliary hosts and the principal host had no real influence on infection levels in auxiliary hosts, measured as either prevalence, intensity or abundance. The analysis revealed differences in the degree of specialization among major groups of parasites: in terms of abundance or intensity, auxiliary hosts were less important for cestodes than for nematodes and copepods. The lack of an effect of taxonomic distance may indicate that ecological similarity among host species, arising from convergence and not from relatedness, is more important than host phylogeny or taxonomy. Although the results are based on a limited number of parasite taxa, they suggest that parasites may be opportunistic in their colonization of new hosts, and not severely constrained by evolutionary baggage.
Heterogeneous model of schistosomiasis transmission and long-term control: the combined influence of spatial variation and age-dependent factors on optimal allocation of drug therapy
Authors: GURARIE D. , KING C. H.
Published: December 2004

Prior field studies and modelling analyses have individually highlighted the importance of age-specific and spatial heterogeneities on the risk for schistosomiasis in human populations. As long-term, large-scale drug treatment programs for schistosomiasis are initiated in subSaharan Africa and elsewhere, optimal strategies for timing and distribution of therapy have yet to be fully defined on the working, district-level scale, where strong heterogeneities are often observed among sublocations. Based on transmission estimates from recent field studies, we develop an extended model of heterogeneous schistosome transmission for distributed human and snail population clusters and age-dependent behaviour, based on a ‘mean worm burden+snail infection prevalence’ formulation. We analyse its equilibria and basic reproduction patterns and their dependence on the underlying transmission parameters. Our model allows the exploration of chemotherapy-based control strategies targeted at high-risk behavioural groups and localities, and the approach to an optimal design in terms of cost. Efficacy of the approach is demonstrated for a model environment having linked, but spatially-distributed, populations and transmission sites.
Spring‐summer frontogenesis at the mouth of Block Island Sound: 1. A numerical investigation into tidal and buoyancy‐forced motion
Authors: Edwards C. A. , Fake T. A. , Bogden P. S.
Published: December 2004

The generation and underlying dynamics of late‐spring temperature and salinity fronts at the mouth of Block Island Sound in the Mid‐Atlantic Bight are examined using a three‐dimensional general circulation model. The model is forced by tidal velocities at its outer boundaries, an estuary/shelf salinity gradient, and surface warming. Runs representing the period from 18 April to 23 May 2000 are investigated through direct examination of the model results and diagnostic calculations that isolate individual processes. Three mechanisms are identified as significantly contributing to the location and structure fronts observed in this region. Vertical mixing produces the necessary horizontal temperature structure within and near Block Island Sound, but the southern frontal boundary is further affected by the subtidal circulation, which is divided into two components defined using a momentum budget analysis. Tidal currents over the complex bathymetry leads to nonlinearly rectified flows, including a headland eddy south of Montauk Point. Circumscribing this feature is a baroclinically adjusted, buoyant outflow from the Long Island Sound estuary. While modifications to the buoyancy forcing can modify the frontal position, it necessarily remains offshore of the tidally driven circulation. Analysis of the salinity anomaly fluxes indicates that both tidal and mean advection are responsible for the overall transport of buoyancy.
Heat flow through a basaltic outcrop on a sedimented young ridge flank
Authors: Wheat C. Geoffrey , Mottl Michael J. , Fisher Andrew T. , Kadko David , Davis Earl E. , Baker Edward
Published: December 2004

One hundred seven thermal gradients were measured in shallow surface sediments using the submersible Alvin within a 0.5 km2 area on and around the 65‐m‐high, mostly sediment‐covered Baby Bare outcrop located on the eastern flank of the Juan de Fuca Ridge. Heat flow values range from 0.35 W m−2, which is close to the average value (0.27 W m−2) for the sediment‐buried 3.5‐Myr‐old crust surrounding the outcrop, to as high as 490 W m−2. Some measurements are purely conductive, whereas others are consistent with upward fluid seepage through this sediment layer. Highest heat flow values are found roughly 10 m below the summit along a ridge‐parallel fault where shimmering water, springs, and communities of clams were found. Heat flow values surrounding a second fault are elevated to a lesser extent (maximum of 9.2 W m−2). The total power output from this 0.5 km2 area is 1.5 MW, about 10 times greater than the conductive power output predicted for a commensurate area of 3.5‐Myr crust. Much of this heat loss is conductive (∼84%), consistent with an independent estimate of the convective heat flux from Rn/heat anomalies in spring fluids and in the water column above the springs. Calculations suggest that the 64°C isotherm, which is the temperature in the surrounding upper crust, is <20 m below the summit, corresponding to a height that is 30 m above the surrounding turbidite plain. These elevated fluid temperatures at shallow depths provide thermal buoyance to drive seafloor seepage from the outcrop.
Structure and dynamics of sheared mantle plumes
Authors: Kerr Ross C. , Mériaux Catherine
Published: December 2004

An extensive series of laboratory experiments is used to investigate the behavior of sheared thermal plumes. The plumes are generated by heating a small circular plate on the base of a cylindrical tank filled with viscous fluid and then sheared by rotating a horizontal lid at the fluid surface. The motion of passive tracers in the plumes is visualized by the release of several dye streams on the hot plate. We systematically examine the dependence of the convective flow on four dimensionless numbers: a velocity ratio, a Rayleigh number, the viscosity ratio, and an aspect ratio. We identify and delineate two transitions in the convective behavior: from a regime where the plume can spread upstream against the shear to a regime where the entire plume is advected downstream, and from a regime of negligible cross‐stream circulation to a regime with significant cross‐stream circulation and thermal entrainment. Our analysis of the steady profiles of the plumes shows that they initially rise with a constant vertical rise velocity. This rise velocity depends on the buoyancy flux and ambient viscosity but is almost independent of the centerline plume viscosity, which suggests that most of the thermal plume has a viscosity that is much closer to the ambient viscosity than the centerline viscosity. As the plumes approach the lid, they decelerate as the viscous drag on them steadily increases. The lateral spreading of the plumes under the lid is found to be well described by similarity solutions derived for the spreading of compositional plumes on a rigid surface, if the effective viscosity of the thermal plumes is taken to be the ambient viscosity rather than the centerline viscosity. A similar theoretical model is found to roughly predict the upstream spreading of thermal plumes at low shear, but it breaks down at moderate to high shear, where the entire plumes are advected downstream. When our results are applied to the Earth, we find that mantle plumes are mostly divided into only two flow regimes in the upper mantle: plumes under slow moving plates experience upstream flow and negligible cross‐stream circulation, while plumes under faster moving plates (including all Pacific plumes) experience significant cross‐stream circulation and are advected downstream. We also demonstrate that geochemical heterogeneities in a plume's source region will result in an azimuthally zoned plume and in an asymmetric geographical distribution of geochemical heterogeneities in the erupted hot spot basalts, as is seen in the Hawaiian, Galápagos, Marquesas, and Tahiti/Society island chains. For individual mantle plumes, we determine their diameter and vertical rise velocity as well as the extent of upstream spreading and the rate of lateral spreading under the lithosphere.
Seasonal and interannual variation in Santa Barbara Basin water temperatures observed in sediment trap foraminiferal Mg/Ca
Authors: Pak Dorothy K. , Lea David W. , Kennett James P.
Published: December 2004

We have generated a Santa Barbara Basin sediment trap Mg/Ca record to evaluate culture‐based calibration equations for the temperate/subpolar planktonic foraminiferal species Globigerina bulloides and Neogloboquadrina pachyderma (dextral). G. bulloides and N. pachyderma Mg/Ca are significantly correlated with seasonal variations in temperature of the near‐surface and subthermocline depths, respectively. The average deviation between Mg‐based and δ18O ‐based temperature estimates is ±0.6°C for G. bulloides and ±0.8°C for N. pachyderma. Differences between Mg‐derived temperatures and instrumental temperatures may be due to cleaning methods, environmental factors such as seasonal variations in foraminiferal depth habitats, or possible secondary effects on Mg/Ca. Core‐top Mg/Ca of both G. bulloides and N. pachyderma is in excellent agreement with average values from the sediment trap, lending strong support for the interpretation of downcore Mg/Ca from these species as annual average near‐surface and thermoclinal temperatures.
Evaluation of the Hill‐Siscoe transpolar potential saturation model during a solar wind dynamic pressure pulse
Authors: Boudouridis A. , Zesta E. , Lyons L. R. , Anderson P. C.
Published: December 2004

Theory, observations, and simulations have shown that saturation of the cross‐polar‐cap potential occurs for high solar wind electric field. One of the parameters that affect the saturation process is the solar wind dynamic pressure. Theoretical arguments predict that higher pressure levels lead to higher transpolar potentials and a slower saturation process. The question arises of how the transpolar potential will respond to sudden enhancements of solar wind pressure in the saturation regime, and if the theoretical model predictions can replicate the observations. We use ionospheric flow data from Defense Meteorological Satellite Program (DMSP) spacecraft to calculate the transpolar potential and compare it with theory before and after a sudden increase in solar wind pressure. We find that the model predictions fall below the observed values for both pressure levels but are particularly lower after the dynamic pressure enhancement. The inclusion of a “viscous” potential, or the introduction of variable ionospheric conductivity, cannot remedy the discrepancy. We suggest that modification of the existing models to include magnetotail processes might be needed to bridge the gap between theory and observations.
A topographic test for the existence of ground ice in the walls of Coprates Chasma, Mars
Authors: Jernsletten Jørn Atle
Published: December 2004

Evidence for the former presence of ground ice and its possible role in the erosion of Valles Marineris trough walls is equivocal. This study aims to determine whether variations in the topographic slope angle of the walls of the trough Coprates Chasma are consistent with predicted temperature‐driven differences in the distribution, thermal condition, and strength of ground ice within its walls. Using Mars Orbiter Laser Altimeter topographic data, 247 profiles were made rim to rim across the trough and measurements made of wall slope angle, mean annual surface temperature, and trough geometry (wall height, rim elevation, and trough width). Variations in these parameters along each trough wall, and differences between the two trough walls, were established. The results indicate that the predicted variations along and differences between the walls in the three‐dimensional distribution of ground ice, and in its thermal condition and strength, are unlikely to have caused the measured variations in trough wall slope angle. These observations imply that ground ice has been absent within the trough walls since the age of formation of the spur‐and‐gully wall morphology. The results preclude the spur‐and‐gully morphology having developed by dry mass‐wasting of material above an ice‐rich cryosphere and indicate the action of liquid water to be a more likely origin. The inferred absence of ice within the walls precludes any role of ice in initiating or mobilizing landslides where they have eroded the spur‐and‐gully morphology.
An Empirically Supported Reconceptualization of African-U.S. Racial Identity Development as an Abnormal Process
Authors: Ajani ya Azibo Daudi , Robinson Jeanene
Published: December 2004

Transformational, developmental process theories of African-U.S. racial identity development are flawed because they conceptualize ontogenetic experience without embedding it in phylogenetic dictates. As a result, culminating psychological states are not depicting identity progression but actually mask a sophisticated regression to a “deracinated,” psychologically misoriented orientation. Therefore, African-U.S. racial identity development is reconceptualized as an abnormal psychology feature of the behavior of otherwise normal persons. This thesis is supported empirically by survey research showing that low identity statuses and purported high identity states evince similar anti-African/Black correlation patterns. African-U.S. identity metamorphosis appears to be a process of identity diffusion, not identity progression. Recommendations for racial identity theory and research and counseling and clinical practice are provided.
Sex Differences in Aggression in Real-World Settings: A Meta-Analytic Review
Authors: Archer John
Published: December 2004

Meta-analytic reviews of sex differences in aggression from real-world settings are described. They cover self-reports, observations, peer reports, and teacher reports of overall direct, physical, verbal, and indirect forms of aggression, as well as (for self-reports) trait anger. Findings are related to sexual selection theory and social role theory. Direct, especially physical, aggression was more common in males and females at all ages sampled, was consistent across cultures, and occurred from early childhood on, showing a peak between 20 and 30 years. Anger showed no sex differences. Higher female indirect aggression was limited to later childhood and adolescence and varied with method of measurement. The overall pattern indicated males’ greater use of costly methods of aggression rather than a threshold difference in anger.
Scripts, Transformations, and Suggestiveness of Emotions in Shakespeare and Chekhov
Authors: Oatley Keith
Published: December 2004

Plays are simulations of social interaction that run on minds rather than on computers. Literary simulations depend on folk theory and have 3 properties that are useful to psychology: (a) They offer scriptlike themes and variations that depict narrative progressions with problem-solving motifs, (b) they enable us to experience emotions and their transformations as we try to understand them, and (c) they offer a greater possibility of insight into emotions than do some experiences of everyday life. In Romeo and Juliet, the successions of the script of falling in love are brought to consciousness. In Hamlet, the emotion line engages the audience in the experience of transformations of emotions. In The Seagull, actors depict emotions as giving rise to relationships among characters, with a suggestiveness that engages the audience. Modes of experience enabled by such simulations augment folk theory. The systemic thinking provided by imaginative literature enables us to understand how emotions initiate, maintain, and transform modes of relationship.
Influence of a boron oxide admixture on the superconducting properties of the bismuth-containing 2212 phase
Authors: Zhgamadze V. V. , Margiani N. G. , Mzhavanadze I. A. , Sabashvili N. G. , Tsintsadze G. A. , Shurgaya G. A.
Published: December 2004

The effect of an admixture of boron oxide B2O3 on the superconducting properties of the bismuth-containing 2212 phase is investigated. It is found that boron doping improves the superconducting transition characteristics of Bi2Sr2Ca1Cu2Oy and Bi1.8Pb0.2Sr2Ca1Cu2Oy samples slowly cooled in a furnace. As the boron content in quenched samples of the 2212 phase increases, Tc and the relative volume of the superconducting fraction are observed to decrease monotonically. Boron doping of the 2212 phase decreases the lattice parameter c.
Energy dissipation of a 180° domain wall in a defect field. Influence of film thickness
Authors: Dzhezherya Yu. I. , Sorokin M. V.
Published: December 2004

An effective equation of motion for a 180° domain wall, taking account of energy losses due to the excitation of flexural waves of the wall when it interacts with point defects, is derived for a ferromagnetic film of arbitrary thickness. The domain wall is studied in the potential well produced by a nonuniform magnetic field. The influence of defects on the motion of a wall with constant velocity and small forced oscillations of the wall are investigated on the basis of exact particular solutions of the equation derived.
Influence of light on the antiferromagnetic-insulator—ferromagnetic-metal phase transition in Pr0.6La0.1Ca0.3MnO3 thin films
Authors: Aleshkevych P. , Baran M. , Szymczak R. , Szymczak H. , Bedarev V. A. , Gapon V. I. , Gnatchenko S. L. , Gorbenko O. Yu. , Kaul’ A. R.
Published: December 2004

The influence of photoillumination on the magnetic and transport properties of epitaxial thin films of the manganite Pr0.6La0.1Ca0.3MnO3 is investigated. It is found that illuminating films with He–Ne laser light increases their magnetization and decreases their electric resistance, stimulating an antiferromagnetic-insulator—ferromagnetic-metal phase transition, which is observed in this crystal in a magnetic field at low temperatures. It is shown that the phase-transition field is appreciably lower after the films are photoilluminated. It is concluded that photoillumination gives rise to the formation and growth of ferromagnetic metallic clusters inside an antiferromagnetic insulating phase. The mechanism of the effect of light on the magnetic and electric states of the manganite Pr0.6La0.1Ca0.3MnO3 could be related with photoinduced electron transfer from Mn3+ to Mn4+ ions, which results in melting of the charge ordering present in this manganite in the antiferromagnetic insulating state, and gives rise to a transition of the crystal into a ferromagnetic metallic phase.
Effect of temperature variation on shift and broadening of the exciton band in Cs3Bi2I9 layered crystals
Authors: Machulin V. F. , Motsnyi F. V. , Smolanka O. M. , Svechnikov G. S. , Peresh E. Yu.
Published: December 2004

The exciton reflection spectra of Cs3Bi2I9 layered crystals are investigated in the temperature region 4.2–300 K with light polarization E⊥c. It is estimated that the energy gap Eg equals 2.857 eV (T=4.2 K) and the exciton binding energy Ry is 279 meV. A nontraditional temperature shift of Eg(T) for layered substances is found for the first time. It is learned that this shift is described very well by the Varshni formula. A transition region in the temperature broadening of the half-width H(T) of the exciton band with increase of temperature is registered in the interval between 150 and 220 K. It is shown that this region may be identified as the heterophase structure region where ferroelastic and paraelastic phases coexist. A surge of H(T) at the point of the ferroelastic phase transition (Tc=220 K) is also observed.
Phonon polaritons in a planar dielectric waveguide in a magnetic field
Authors: Chupis I. E.
Published: December 2004

Infrared and optical polaritons propagating in an isotropic dielectric with metal coatings in the presence of a constant magnetic field parallel to the plane of the layer are studied. It is shown that a constant magnetic field creates nonreciprocal surface modes which did not exist previously at the boundary with the metal. The number of surface modes for the opposite walls is different (1 or 2) and can be changed by switching the directions of the magnetic field or the wave vector. A polariton with a fixed frequency in a magnetic field with a definite orientation propagates along a given boundary in only one direction. A constant magnetic field also creates for volume modes new frequency intervals which are proportional to the first power of the magnetic field, and simultaneously decreases the energy of the volume modes, transferring this energy into surface modes, i.e. a constant magnetic field “pushes” the field of an electromagnetic wave out of the interior volume and onto the surface of the dielectric. This effect is proportional to the magnitude of the constant magnetic field and the thickness of the dielectric layer.
Photoinduced lowering of the valence of vanadium ions in the garnet NaCa2Mn2V3O12
Authors: Gnatchenko S. L. , Eremenko V. V. , Kachur I. S. , Piryatinskaya V. G. , Slavin V. V. , Shapiro V. V. , Kosmyna M. B. , Nazarenko B. P. , Puzikov V. M.
Published: December 2004

Measurements of the spectral distribution of the light absorption coefficient in the garnet NaCa2Mn2V3O12 are performed in a wide range of wavelengths. The influence of unpolarized illumination of a crystal on the light absorption spectrum is investigated. A substantial long-lived photoinduced effect is observed at low temperatures. This effect is manifested as a change in the spectral distribution of the light absorption coefficient and reflects a lowering of the valence of the vanadium ions under the influence of photoillumination.
Observation of the electric induction due to a second-sound wave in He II
Authors: Rybalko A. S.
Published: December 2004

It is shown experimentally that the relative motion of the superfluid and normal components of He II in a second-sound wave is accompanied by the appearance of electric induction. The process is reversible. It is shown that the amplitude ratio of the temperature and induction potential oscillations is a temperature-independent constant equal to 2.3×104 K/V.
Virus evolution: disease emergence and spread
Authors: Gould A. R.
Published: December 2004

Many viruses with RNA genomes have genetically diverse populations called quasispecies. The representation of any particular sequence within this quasispecies is a result of interactions between the host and environmental factors affecting the replication of the virus. Important biological properties are a direct result of the levels of diversity in the quasispecies ‘cloud size’, including adaptability and host range. RNA viruses have become the model system for the analysis of viral evolution due to the inherent error-prone nature of their genome-replicating enzymes that lack a proof-reading function. However, these viruses have also risen in their importance, due to the nature of the diseases that they inflict upon man as well as the crops and animals on which we are dependent. The emergence of previously described viruses into new geographic locations or of previously undescribed viruses into a new host or environment can be explosive and have far reaching consequences. Recent examples include human immunodeficiency virus, West Nile virus, Newcastle disease virus, bluetongue virus and henipaviruses. This paper describes some recent incidents and our state of knowledge in this area.
Future impact of food safety issues on animal production and trade: implications for research
Authors: Edgar J.
Published: December 2004

This review describes the emergence of food safety as an important factor influencing international trade and discusses why it will be increasingly so into the foreseeable future. The continuing development of an international framework for conducting food safety risk analysis is summarised. Livestock researchers have an important role to play in recognising and warning of potential food safety threats and in generating risk assessment data. The need for greater awareness of food safety issues among livestock researchers in Australia is suggested. Possible strategies and infrastructure for Australian institutions engaged in livestock health and production research, which may assist in strengthening the interface with government agencies responsible for protecting consumers and exports from food safety threats, are also considered. Corynetoxins are used as an example of a potential food safety issue of relevance to livestock production in Australia.
Gene transfer: potential to enhance the genome of Atlantic salmon for aquaculture
Authors: Fletcher G. L. , Shears M. A. , Yaskowiak E. S. , King M. J. , Goddard S. V.
Published: December 2004

Over the past 20 years we have generated stable lines of transgenic Atlantic salmon possessing either antifreeze protein (AFP) genes or a salmon growth hormone (GH) gene construct. The AFP gene transfer studies were initiated in 1982. The AFP transgene integrated into salmon genomic DNA and AFP has been found in the blood of all 5 generations to date. However, AFP levels are low and a means to raise these levels needs to be developed. Our GH gene transfer studies were initiated in 1989. Evidence to date indicates that a single copy of the GH transgene integrated into chromosomal DNA and has been passed down in Mendelian fashion, along with its rapid growth phenotype, over 6 generations. Laboratory studies indicate that our GH transgene enhances growth rates with Atlantic salmon reaching market size (4–6 kg) a year earlier than non-transgenics cultured commercially in Atlantic Canada.
This GH gene transfer technology was patented and licensed to Aqua Bounty Farms Inc., and the transgenic salmon are currently under review by various government regulatory authorities in the USA and Canada for use in commercial aquaculture ventures. Our experience with the regulatory authorities, the industry and the press indicates that the successful introduction of transgenic salmon into the aquaculture industry involves issues concerning not only science but also food safety, environmental safety, animal welfare and consumer acceptance. This communication centres on our experience with Atlantic salmon and outlines our plans and progress towards demonstrating the safety of transgenic fish to the consumer and to the environment.
The use of animals in research: counting the costs and the benefits
Authors: Rickard M. D.
Published: December 2004

The Australian Code of Practice for the Care and Use of Animals for Scientific Purposes requires Animal Ethics Committees to assess the merits of any research proposal involving the use of sentient animals. As part of that assessment they should make a judgment as to whether or not the costs to the welfare of the experimental animals are outweighed by the benefits of the predicted experimental outcome (i.e. conduct a cost–benefit analysis). This paper describes one approach that has been proposed to assist Animal Ethics Committees to take all factors into account when making this judgment. When agricultural animals are used in research the potential benefits are usually measured in terms of improved health and welfare or increased productivity when the research outcomes are applied to other animals reared in agricultural enterprises. When the aim of a project is to improve the health and welfare of the animals (i.e. ‘animal benefit’), the benefits are usually obvious and counting the cost is straightforward even if the impact on the animals under experimentation is quite extreme (e.g. death as an unavoidable endpoint in a vaccination experiment). Where the benefits accrue solely in terms of increased productivity or economic gain (i.e. ‘human benefit’), then balancing the costs and the benefits can be more problematical because people’s personal beliefs and their orientation towards animal welfare influence their assessment. Economists indicate that it is not increased productivity per se that generates value but consumption. Therefore, consumer perceptions of any adverse impact that gains in productivity have on the welfare of farmed animals can play a significant role in determining the ultimate benefit (value) of a particular piece of research with the sole aim to increase production and economic gain. This paper will explore some postulated relationships between productivity and animal welfare which could influence consumer preferences and hence the cost–benefit analysis.
Somatic cell nuclear transfer
Authors: Hill J. R.
Published: December 2004

Nuclear transfer research became front-page news when the birth of Dolly, the cloned ewe, was reported by Ian Wilmut and Keith Campbell in 1997. Since Dolly’s birth, offspring from many other species have been produced using somatic cell nuclear transfer. While Dolly’s birth transformed embryology research, her death in February 2003 marked the beginning of the next phase of research and development. This period will determine the scale of the commercial and societal benefits that accrue from somatic cell nuclear transfer and transgenics.
Proof of concept for many of the potential benefits of somatic cell nuclear transfer has already been demonstrated. Desirable genotypes have been cloned, further insights into the nuclear reprogramming process have been achieved, and precision gene insertions/deletion has been demonstrated.
It is likely that nuclear transfer can be adapted to ‘copy’ individuals from any mammalian species. Offspring have been produced using cells from sheep, mice, cattle, goats, pigs, rabbits and a cat. It appears very likely that copying of other species such as horses will follow shortly. However, early results from monkeys suggest that somatic cell nuclear transfer in primates may require further intensive study before the likelihood of success can be predicted. The nuclear transfer process is far less efficient at producing healthy offspring than the natural process of combining a sperm with an egg. Fewer normal embryos, fetuses and offspring are produced from somatic cell nuclear transfer than from other assisted breeding techniques. The reasons for this appear to be related to abnormal expression of key developmental genes. Many of these genes are imprinted genes, which rely on correct methylation patterns of the genome that are established in the first week of life. Research into this area not only aids further development of the nuclear transfer technique but is also important for basic research into understanding the nuclear reprogramming process in mammals.
The combination of nuclear transfer with gene insertion/deletion techniques has permitted a quantum leap in the efficiency of producing livestock with an additional ‘value adding’ gene. This has resulted in more economical production of animals that carry a specific valuable gene, such as a gene to enable production of novel or valuable proteins in their milk. Precision gene insertions or deletions will become more available in the near term so that this technique will become as important for testing gene function for agricultural applications as it is in mice for biomedical uses.
Our challenge for the next decade is to fine-tune the somatic cell nuclear transfer technique so as to achieve more normal development rates. At the same time we need to increase the efficiency of targeted gene insertion or deletion so that the 2 techniques can be effectively combined to utilise the information on gene function created by livestock gene discovery programs.
Decomposition of Mercuric Chloride and Application to Combustion Flue Gases
Authors: Wilcox Jennifer , Blowers Paul
Published: December 2004

Environmental Context. The toxicity of the volatile metal mercury is well known; this Hg0 form accounts for about 99% of atmospheric mercury and the remainder the water-soluble oxidized (Hg+, Hg2+) form. The release of mercury from the atmosphere is measurable by a drop in the Hg0 levels, but to establish realistic scientific and regulatory standpoints the rate in which Hg0 converts to the oxidized forms needs to be understood. Conversely, from an industrial standpoint, understanding the rate at which the oxidized forms convert to Hg0 allows for better waste-scrubbing processes.
Abstract. Theoretical rate constants and activation energies are predicted for the decomposition of mercuric chloride through the use of relativistic pseudopotentials for mercury at the B3LYP level of theory. The method and basis set combinations are validated through a comparison of theoretically determined geometries, frequencies, and reaction enthalpies to experimental values found in the literature. In addition, the theoretically predicted rate constants are compared to rate constants that have been predicted through combustion modelling of this reaction.
Cadmium Adsorption by Chlamydomonas reinhardtii and its Interaction with the Cell Wall Proteins
Authors: Kola Heliana , Laglera Luis M. , Parthasarathy Nalini , Wilkinson Kevin J.
Published: December 2004

Environmental Context. In natural waters, trace metals levels are largely controlled by microbiology; organisms take up, metabolize, store, and detoxify the metals. However, aquatic organisms may regulate their own uptake via dynamic processes that result in a system that is far from equilibrium. By examining the model title alga with a battery of techniques, a more realistic assessment of metal uptake and metal regulatory processes could be gained.
Abstract. Cadmium adsorption by a wild type strain of Chlamydomonas reinhardtii and a cell wall-less mutant was quantified as a function of Cd speciation in a well-defined aqueous medium. For both strains, Cd adsorption to the cell surface was not predicted by a single-site (Langmuirian) model. Indeed, no saturation of the cell wall was observed, even for Cd concentrations in excess of 5 × 10−3 M. A continual production of Cd binding sites appeared to be responsible for the observed increase of Cd adsorption with time. SDS-page separations and measurements of the protein content of algal supernatants demonstrated that organic matter was released by the algae, both in the presence and absence of Cd. Both the nature (e.g. polysaccharides, proteins) and the quantity of exudate production was influenced by the physicochemistry of the external medium. Measurements using the permeation liquid membrane (PLM) and anodic stripping voltammetry (ASV) demonstrated that dissolved cadmium was rapidly complexed by the organic exudates produced by the algae.
Attempts towards derivation and establishment of bovine embryonic stem cell-like cultures
Authors: Maddox-Hyttel Poul , Gjørret Jakob O.
Published: December 2004

Current knowledge on the biology of mammalian embryonic stem cells (ESC) is stunningly sparse in light of their potential value in studies of development, functional genomics, generation of transgenic animals and human medicine. Despite many efforts to derive ESC from other mammalian species, ESC that retain their capacity for germ line transmission have only been verified in the mouse. However, the criterion of germ line transmission may not need to be fulfilled for exploitation of other abilities of these cells. Promising results with human ESC-like cells and adult stem cells have nourished great expectations for their potential use in regenerative medicine. However, such an application is far from reality and substantial research is required to elucidate aspects of the basic biology of pluripotent cells, as well as safety issues associated with the use of such cells in therapy. In this context, methods for the derivation, propagation and differentiation of ESC-like cultures from domestic animals would be highly desirable as biologically relevant models. Here, we review previously published efforts to establish bovine ESC-like cells and describe a procedure used in attempts to derive similar cells from bovine Day 12 embryos.
115 CYTOLOGICAL ANALYSIS OF HEPATIC GENE EXPRESSION AND IMMUNOLOGICAL RESPONSE OF MHC ANTIGENS IN MOUSE AMNIOTIC EPITHELIAL CELLS
Authors: Mitani T. , Nagai T. , Suzuki D. , Ukida Y. , Kato H. , Matsumoto K. , Saeki K. , Hosoi Y. , Iritani A.
Published: December 2004

Human amniotic epithelial cells (hAECs) have been reported to have unique properties. They express almost no class I and class II MHC antigens and lack response to interferon-γ (IFN-γ) which mediates the expression of those MHC molecules. Moreover, hAECs express some genes characteristic of hepatic cells. Therefore, hAECs seem to have multipotency and are expected to substitute for hepatic tissues in part. We aimed to develop the experimental model for investigating AECs in mice (mAECs). In this study, we examined the induction of MHC molecules by IFN-γ and the hepatic gene expression in mAECs. Murine amniotic membranes were collected from C57BL/6J females at 17.5 days of gestation. They were digested by 0.03% hyaluronidase followed by 0.2% collagenase treatment. Dissociated mAECs were cultured on dishes in DMEM supplemented with 10% FBS at 37°C under 5%CO2 in air. Embryonic fibroblasts (EFs) collected from C57BL/6J fetuses at 13.5 dpc were cultured in the same condition as mAECs. In Experiment I, the effect of IFN-γ on induction of MHC molecules in mAECs was examined. mAECs and EFs cultured in the presence or absence of IFN-γ at 1 × 103 U mL−1 for 72 h were recovered and incubated with FITC-conjugated antibodies against mouse H-2 MHC class I or I-A/I-E MHC class II antigens. The cells were analyzed by flow cytometry. In Experiment II, the expression of the genes in mAECs was examined by RT-PCR. mRNA was purified from adult liver, EFs, fresh mAECs, and mAECs cultured for 5 days. As the genes characteristic for hepatic cells, HNF-3α, HNF-3β, HNF-3γ, HNF-4, transthyretin (TTR), albumin, α-fetoprotein (AFP), glucose-6-phosphatase (G6P), and asialoglycoprotein receptor-1 (Asgr1) were examined. In Experiment I, cell-surface expression of class I and class II MHC antigens in response to IFN-γ was observed weakly in mAECs as compared to EFs, suggesting different property in hAECs which lack the expression of those antigens. In Experiment II, RT-PCR analysis showed that all of the genes except G6P were expressed in fresh mAECs. However, the expression of transcription factors such as HNF-3α, HNF-3β, HNF-4, and TTR, serum proteins such as albumin and AFP, and Asgr1 decreased after in vitro culture, contrary to the case of hAECs in which, for example, albumin appeared after cultivation. In conclusion, it was evident that mAECs have quite different properties, both in the inductivity of MHC molecules and the expression of hepatic genes, from hAECs.
This work was supported by Wakayama Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence of the JST, and by a Grant-in-Aid for the 21st Century COE Program of the Japan MEXT.
129 RESPIRATION ACTIVITY OF BOVINE EMBRYOS CULTURED IN SERUM-FREE AND SERUM-CONTAINING MEDIA
Authors: Abe H. , Shiku H. , Aoyagi S. , Matsue T. , Hoshi H.
Published: December 2004

Oxygen consumption is a ubiquitous parameter which can provide valuable information about metabolic mechanisms and embryo quality. Recently, we succeeded in non-invasively and quantitatively determining oxygen consumption of individual bovine embryos by the scanning electrochemical microscopy (SECM). The aim of this study was to assess by SECM the oxygen consumption of individual bovine embryos at different developmental stages cultured in serum-free and serum-supplemented media. Bovine oocytes were matured in IVMD101 medium [Research Institute for the Functional Peptides (IFP), Shimojo, Yamagata, Japan] and inseminated in BO-based medium. For serum-free culture, inseminated ooocytes were cultured to the blastocyst stage in IVD101 medium in an atmosphere of a low oxygen condition (5% CO2/5% O2/90% N2) at 38.5°C. For serum-supplemented culture, inseminated oocytes were cultured in HPM199 medium (IFP) supplemented with 5% calf serum (HPM199 + CS) in the presence of bovine cumulus/granulosa cells in a humidified atmosphere of 5% CO2 in air. Oxygen consumption by individual bovine embryos was non-invasively quantified by the SECM measuring system. Some embryos were prepared for transmission electron microscopy. The oxygen consumption rates are presented in the table. Oxygen consumption rates (F) of the single embryos were low from 2-cell to 8-cell stages (0.45–0.52 × 10−14 mol s−1). In serum-free culture, an increase in oxygen consumption rate was found at the morula (1.03 × 10−14 mol s−1) stage, and blastocysts showed an even higher oxygen consumption rate (1.86 × 10−14 mol s−1). On the other hand, the oxygen consumption of morulae and blastocysts produced in serum-supplemented medium was lower than that of embryos cultured in serum-free medium. Electron microscopic study demonstrated that many of the mitochondria of morulae and blastocycts cultured in HPM199 + CS medium were an immature form, indicating a correlation between respiration activity and development of mitochondria. These results suggest that the culture conditions affect the respiration activity of bovine embryos. The SECM procedures may have a wide application for judging embryo quality and culture conditions for embryos.

Table 1.
Oxygen consumption rates (F × 10−14 mol s−1) of the bovine embryos at various developmental stages