bluuebunny/crossref_metadata_2025 huggingface dataset:
Educating young consumers – a food choice model
Authors: Hamilton Jennifer , McIlveen Heather , Strugnell Christopher
Published: March 2003

It has been acknowledged that it is only by obtaining a more detailed understanding of food choice that people’s diets can be improved. In Northern Ireland, research into food choice has been limited yet the Province has the second highest rate of heart disease in the world, indicating the need for change. This study investigated the food choices of 9‐ to 17‐year‐olds in Northern Ireland and the influential factors. A range of research techniques were employed incorporating both qualitative and quantitative methods, namely observations, focus groups, picture associations, dietary case studies and questionnaires. The research indicated that the dietary patterns adopted by this group are characterized by a high consumption of fat, yet the reduction of fat tends to dominate the overall strategy for the prevention of obesity and lowering the risk of coronary heart disease. In addition, a high consumption of sugar products was evidenced along with a distinct dislike for healthier alternatives such as fruit and vegetables. The ‘skipping’ of meals, especially breakfast and a high prevalence of snacking was also apparent. However, these eating habits were found to be affected by various factors such as age and gender, emphasizing the complex nature of food choice. The findings from this research enabled the development of a model relating to the food choices of 9‐ to 17‐year‐olds in Northern Ireland, highlighting the influential factors and subsequent health implications.
The impact of lianas on tree regeneration in tropical forest canopy gaps: evidence for an alternative pathway of gap‐phase regeneration
Authors: Schnitzer Stefan A. , Dalling James W. , Carson Walter P.
Published: March 2003

1  Regeneration in forest canopy gaps is thought to lead invariably to the rapid recruitment and growth of trees and the redevelopment of the canopy. Our observations, however, suggest that an alternate successional pathway is also likely, whereby gap‐phase regeneration is dominated by lianas and stalled in a low‐canopy state for many years. We investigated gap‐phase regeneration in an old‐growth tropical forest on Barro Colorado Island (BCI) in Panama to test the following two hypotheses: (i) many gaps follow a pathway in which they remain at a low canopy height and are dominated by lianas and (ii) the paucity of trees in this pathway is a function of liana density.

2
 We surveyed a total of 428 gaps of varying ages (c. 5, c. 10, and 13+ years old) and identified those which followed the conventional pathway of regeneration and others that remained stalled in a low‐canopy state for many years and were dominated by either lianas or palms. Each of these pathways will likely have different successional trajectories that will favour the growth of a distinct suite of mature species and ultimately result in contrasting species composition.

3  The successional pathway of liana‐dominated, stalled gaps is common throughout the forest. We estimate conservatively that 7.5% of the gaps that form each year will follow this pathway, probably due to the suppression of tree regeneration by lianas, and that many of these stalled gaps will persist for much longer than 13 years. Consequently, a high proportion of gaps in the forest at any given time will be stalled. Furthermore, liana tangles, which persist in the tropical forest understorey for extended periods of time, almost certainly originate in these gaps.

4  Liana abundance was positively correlated with pioneer tree abundance and diversity while negatively correlated with non‐pioneer tree abundance and diversity. Thus, lianas appear to inhibit non‐pioneer tree survival while indirectly enhancing that of pioneer trees.

5  Lianas are abundant in many types of tropical and temperate forests and a successional pathway involving liana‐dominated, stalled gaps may therefore be frequent and widespread.
Tree recruitment at theNothofagus pumilioalpine timberline in Tierra del Fuego, Chile
Authors: Cuevas Jaime G.
Published: March 2003

1 Nothofagus pumilioforms an abrupt alpine timberline (AT) at 690 m a.s.l on Balseiro mountain, 54 °S, Tierra del Fuego, Chile. Fruit and seed rain (quantity and quality), emergence, density and survival of seedlings were studied across an altitudinal gradient (450–740 m) from within the forest to above the AT.

2 Fruit rain generally declined with altitude but increased between 630 and 690 m before falling sharply beyond the AT. The proportion of seed‐bearing fruits, seed viability and seed mass also declined with increasing altitude, but showed no recovery in the vicinity of the AT.

3 Fruit rain decreased exponentially with distance into the alpine zone, so that effective dispersal rarely exceeded 20 m beyond the AT and few of these fruits contained seeds.

4 Seedling emergence and density decreased with altitude both within the forest and into the alpine zone so that seedlings were found no more than 10–20 m above the AT. Even in 1996, when fruit production was high, successful seedling recruitment was limited to lower altitudes.

5 There was little correlation between altitude and the percentage survival of naturally occurring seedlings within the forest. However, transplanted seedlings survived better at the AT itself than immediately inside the forest, and showed high mortality in the alpine zone.

6 The most severe bottlenecks for tree recruitment within the forest appeared to be seedling emergence and seed production. Above the AT, seed viability and emergence were the principal bottlenecks.

7 Although not all demographic variables declined altitudinally, the overall probability of adult establishment decreased with increasing altitude and became very low once the protection by the tree canopy became unavailable. A demographic model explaining the origin and abrupt character of the AT studied is presented.
Testing patterns of zonation in mangroves: scale dependence and environmental correlates in the Sundarbans of Bangladesh
Authors: Ellison Aaron M. , Mukherjee Barid B. , Karim Ansarul
Published: March 2003

Summary 1 Associations between abiotic variables and patterns of species distribution and abundance are a major preoccupation of community ecologists. In many habitats, this association is manifest in discrete zones of vegetation.

2 We used statistical methods to examine tree species distribution patterns in relatively undisturbed regions of the Sundarbans of Bangladesh. We tested the hypothesis that mangroves occur in discrete zones with respect to elevation. These data were gathered with explicit attention to local and regional differences in edaphic characteristics so that species‐environment relationships could be analysed at several spatial scales.

3 Correlations were also assessed between mangrove species composition and edaphic variables that co‐vary with elevation, i.e. salinity, field capacity, cation exchange capacity, percentage silt, and mangrove physiognomic category (slope, basin, levee and flat).

4 Quantitative statistical analysis using randomization techniques failed to detect species zonation along any of 33 individual 200‐m transects, within 1‐km2 blocks, or within 1200‐km2 regions.

5 Canonical correspondence analysis relating edaphic variables to species distributions accounted for a total of only 24% of the variance in species composition.

6 Our data suggest that the absence of zonation in the Bangladesh Sundarbans reflects the underlying biology of the system and is not an artefact of long‐term human disturbance.
Macrophyte decline in Danish lakes and streams over the past 100 years
Authors: Sand‐Jensen Kaj , Riis Tenna , Vestergaard Ole , Larsen Søren Erik
Published: March 2003

1 Freshwater habitats in cultivated and densely populated lowland regions of Europe have experienced profound changes during the last 100 years. We take advantage of the long interest in aquatic plants in Denmark to compare the submerged flora in lakes and streams in 1896 and 1996.

2 Most of the lakes which contained a diverse submerged vegetation 100 years ago now have the high phytoplankton biomasses and summer transparencies below 2.0 m characteristic of eutrophication. The majority of 17 lakes included in both old and recent studies have lost all or most of their submerged species. Species richness for those lakes that were vegetated did not, however, differ significantly between old and recent studies.

3 Species richness declined markedly in the 13 streams included in both studies. Over all sites, there was also a significant decline of species richness per locality. Potamogeton species declined from 16 to 9, despite an 8‐fold increase in the number of sites surveyed.

4 Similar compositions and rank‐abundances of Potamogeton species in lakes and streams studied 100 years ago reflect suitable growth conditions and mutual exchange of propagules. Today, low habitat diversity and frequent disturbance in streams and low recruitment from lakes favours only robust, fast‐growing species capable of regrowth following weed cutting and dredging.

5 A positive interspecific relationship observed in the contemporary stream vegetation between mean local abundance and number of occupied sites was probably promoted by redistribution of plants as a result of disturbance and efficient dispersal in the interconnected stream network.

6 The freshwater macrophyte flora in north‐west Europe presently includes a high proportion of rare species which are threatened by extinction. Both species typical for oligotrophic conditions (e.g. P. filiformis and P. polygonifolius) and another group of large, slow‐growing species (e.g. P. alpinus, P. lucens, P. praelongus and P. zosterifolius), were once common but are now infrequent, while other transient species have remained rare (e.g. P. acutifolius, P. colouratus, P. densus and P. rutilus). The presence of many species that barely survive in small and distant populations will make re‐assembly of submerged aquatic communities difficult.
Intensity of intra‐ and interspecific competition in coexisting shortgrass species
Authors: Aguiar Martín R. , Lauenroth William K. , Peters Debra P.
Published: March 2003

Bouteloua gracilis and Buchloë dactyloides are dominant species in the shortgrass steppe. Previous studies have suggested that these species have similar resource requirements and, as there is no temporal segregation in growth, we suggest that competition for below‐ground resources should be intense. Classical competition theory predicts that, under stable conditions, coexistence of species with similar requirements can occur if intraspecific competition is more intense than interspecific competition. We therefore compared the competitive abilities of the two species under both inter‐ and intraspecific conditions, another determinant of coexistence in plant communities.

A 3‐year experiment was conducted in a small homogeneous area and a separate 2‐year experiment was conducted in a larger area. In both experiments, a hexagonal planting design was used to achieve all possible combinations of species and to control plant size and neighbourhood asymmetries at the start of the experiment. Half the target plants were grown within steel cylinders to reduce below‐ground competition.

We found similar results in the two experiments. Plant biomass and seed production were always higher in plants growing with reduced competition, although seed production was quite variable. Relative competition intensity did not differ between intraspecific and interspecific competition.

Our results suggest that competition between these coexisting shortgrasses is intense, but do not support the prediction of a difference between intra‐ and interspecific competition. We discuss alternative explanations.
The expansion history of a sexual and asexual species ofCortaderiain California, USA
Authors: Lambrinos John G.
Published: March 2003

The expansion histories of two South American species ofCortaderia, similar in morphology but differing profoundly in their breeding systems, were compared in California, USA.

 Both species were introduced to California in the mid‐1800s, but herbarium records indicate that the sexualC. selloanahas expanded spatially at twice the rate of the asexualC. jubata.

 The invasiveness ofC. selloanahas increased over time, whereas that ofC. jubatahas remained relatively constant. Populations ofC. selloananow occupy more vegetation types and more non‐ruderal habitats thanC. jubata.

 Populations ofC. selloanahave experienced directional morphological change, whereas the morphology ofC. jubatahas been constant over the 90 years for which preserved specimens are available.

 The invasion of an alien species appears to be a malleable process, rather than a singular event. Species traits, such as inbreeding, can be advantageous at some stages but disadvantageous at others. Alien species also adjust over time to the novel and diverse selective regimes that they encounter as they expand spatially. Sexual species may have a greater ability to adjust to diverse selective landscapes relative to asexual species.
Long‐term effects of changes in goose grazing intensity on arrowgrass populations: a spatially explicit model
Authors: Mulder Christa P.H. , Ruess R.W.
Published: March 2003

Field studies on effects of geese on arrowgrass (Triglochin palustris) on the Yukon‐Kuskokwim Delta (SW Alaska) have demonstrated that Pacific black brant geese (Brant bernicla nigricans) can have both positive and negative effects on arrowgrass populations, but cannot predict unambiguously the effects of increased goose numbers on arrowgrass demography.

 A cellular automata model was used to predict effects of changes in goose grazing intensity on small‐scale (within‐patch) arrowgrass dynamics. We examined effects of making some of the plant competitors edible to geese, of goose faeces increasing arrowgrass reproduction but reducing size of ungrazed arrowgrass, and of the presence of other species protecting arrowgrass from grazing. We also compared the effects of a random vs. patchy distribution of geese, and of incorporating threshold numbers of arrowgrass below which grazing ceased.

 The results indicate that arrowgrass populations are likely to be highest at medium to high levels of grazing. Inclusion of edible competitors and positive effects of faecal deposition resulted in greater changes in arrowgrass population dynamics than did inclusion of associative refuges.

 For a given grazing intensity, models generally resulted in lower arrowgrass populations with increased aggregation if distributions of geese were patchy, suggesting that decreased colonization may result from lower dispersal.

 Inclusion of a feedback effect (grazing only above a certain plant population) caused arrowgrass populations to persist for much longer. Temporal variability in whether plots were grazed (unrelated to arrowgrass numbers) could not account for this result.

 The model results suggest that knowledge of both small‐scale and large‐scale foraging behaviour is needed to predict the long‐term effects of goose grazing on arrowgrass. Small‐scale effects on the population may be particularly important where dispersal distances are short. The ability of plant populations to persist locally may be increased if grazing is suspended when herbivory reduces forage plants below a threshold level.
The effects of seed predators on the recruitment of mangroves
Authors: Clarke Peter J. , Kerrigan Raelee A.
Published: March 2003

Propagule (diaspore) predation by crabs has been shown to be a major source of mortality for mangroves. We measured predation by crabs on seeds of nine tropical mangrove species in multifactorial experiments by following the fates of tethered propagules.

We tested whether planting, intertidal position and canopy gaps influenced predation of propagules and whether the predation of propagules was reduced in the presence of conspecifics. We also tested if predation influenced patterns of propagule establishment.

Mortality due to predation ranged from 22 to 100%, with Aegiceras corniculatum > Avicennia marina > Bruguiera parviflora > Aegialitis annulata > B. exaristata > Ceriops australis > C. decandra=B. gymnorrhiza > Rhizophora stylosa. Initial predator preference was correlated with the size of propagules.

Propagule planting (prone vs. implanted) and canopy type had the largest magnitude of effects across all species for treatment effects. Propagules dispersed in the prone position had more mortality while those dispersed into canopy gaps were generally less preyed upon. Three species were tested for dominance‐predation by regression of stand relative density with final predation by crabs for canopy treatments. No species had significant effects that supported the hypothesis.

Predation by crabs often changed with intertidal position but showed no consistent pattern among species or gap treatments. Interactions of canopy treatment and tidal position showed that predation by crabs did not have a major influence on the zonation of mangroves in our study sites.

Analyses of covariance of predation and establishment showed that establishment success is strongly controlled by predation in six of the nine species tested. This suggests that herbivores have a greater impact on recruitment than do microhabitat effects on resources. The combined effects of predator refuge and growth preference enhance recruitment in large canopy gaps. Crab predators appear to maintain the floristic similarity between canopy gaps and surrounding forests in tropical mangrove forests of northern Australia by removing allopatric species from gaps.
Stress tolerance of rare and common moss species in relation to their occupied environments and asexual dispersal potential
Authors: Cleavitt Natalie L.
Published: March 2003

Species rarity in mosses may be linked to narrow physiological tolerance and habitat specificity of established colonies and gametophyte fragments (i.e. fragments of stem apices). Stress tolerance and habitat light and moisture were compared for three rare and three common moss species.

Observed habitat specificity was more likely to correspond to physiology in the common species. In particular, one common species,Mnium spinulosum, was limited by intolerance of high light conditions and is characteristic of deeply shaded conifer stands, while another,Bryum pseudotriquetrum, lacked desiccation tolerance and is typical of moist areas such as stream banks. However, the rare species,Mielichhoferia macrocarpa, which occurred in the darkest and wettest sites was not intolerant of high light or desiccation.

The relationship between desiccation tolerance and habitat moisture (based on a mesic to xeric scale) was less clear than in prior bryophyte studies, suggesting that a more rigorous quantification of habitat moisture is needed.

Contrary to predictions, the rare species did not have narrower physiological tolerances than the common species. The match between environment and physiology for common species probably results from their occupation of more of the potentially suitable sites.

There may also be selection for broader physiological tolerance in rare species resulting from their greater reliance on asexual reproduction, which might explain their relatively high desiccation tolerance both as colonies and fragments.
Experimental derivation of functions relating growth ofArabidopsis thalianato neighbour size and distance
Authors: Purves D. W. , Law R.
Published: March 2003

A dynamic competition kernel for a plant growing in the presence of a neighbour is a function describing how the competitive effect experienced by the plant depends on its own size, and the size of and distance to a neighbour. Competition experiments onArabidopsis thalianawere used to derive dynamic competition kernels for this species.

The experiments entailed growing target plants in isolation, and with single neighbours of different relative sizes, and at different distances. Growth was determined from repeated measures of the area occupied by each plant. Target plants with smaller neighbours, or with neighbours that were further away, grew to a larger size than targets with larger, or closer, neighbours.

Relative growth rate (RGR) of isolated plants was best described by the Gompertz equation, a standard plant growth equation that reducesRGRin proportion to the logarithm of plant size.

Competition kernels were constructed by modifying the Gompertz equation to include the competitive effect of a neighbour. Alternative kernels (including the zone of influence model), with and without a parameter of asymmetry of competition, were constructed from observed growth rates of target plants with neighbours over short time intervals. The kernels were evaluated based on their ability to predict the size of targets and neighbours over a much longer time period.

The kernel that best described growth overall was a simple function proportional to the logarithm of neighbour size, and decreasing with distance to the neighbour. The zone of influence model was best able to describe the effects of distance on competition, but was relatively unsuccessful when the two plants differed substantially in size. Including a parameter for asymmetry did not provide any notable improvements in predictive ability, and in many cases made the predictions worse.
Using the Internet to teach melanoma management guidelines to primary care physicians
Authors: Harris John M. , Salasche Stuart J. , Harris Robin B.
Published: March 2003

The aim of this study was to determine whether a brief Internet‐based education programme could improve physicians’ abilities to manage pigmented skin lesions. A pre‐test–post‐test assessment was used of subjects’ knowledge of skin cancer, confidence in their management abilities and actual ability to recommend appropriate treatment for 20 hypothetical patients with pigmented skin lesions. The setting was the general medicine service of an academic medical centre. Seventeen volunteer medical students, house officers and faculty members took part in the study. Following the pre‐test, subjects completed a 1‐hour computer‐based educational programme, distributed via the Internet, presenting a guideline for recognizing and managing potentially malignant pigmented skin lesions. The guideline was based on the ABCD rule and the Glasgow seven‐point checklist. The educational programme had a positive effect on the subjects’ overall skin cancer knowledge and had significantly positive effects on their confidence and ability to apply the management guideline. Based on the guideline criteria, the subjects made the correct management decision on the clinical scenarios 63.2% of the time before the programme and 74.1% of the time after the programme (P = 0.002). We were able to teach melanoma management guidelines to physicians and medical students using a brief, interactive computer programme distributed via the Internet. Such an approach is more cost‐effective than classroom teaching and could be used to improve the clinical skills of practising physicians to recognize and manage early melanomas. This approach to distributed learning could also be used to teach other clinical guidelines to physicians.
Telephone reporting in the consultant–generalist relationship
Authors: DO Thomas A. Haldis , MD James C. Blankenship
Published: March 2003

Rationale, aims and objectives The aim of this paper is to examine the issue
of telephone reporting by consultants in the medical community, which is rarely used
in medicine today. Methods The paper reviews principal publications addressing
this field that have shown that communication between consultants and primary care
physicians has many shortcomings, frequently leaving the primary care physician with
unanswered questions. Discussion and conclusions We present the value of routine telephone reporting by consultants to their primary care counterparts and also discuss possible future implications of communication via electronic mail.
Investigation of within‐study selective reporting in clinical research: follow‐up of applications submitted to a local research ethics committee
Authors: Hahn S. , Williamson P. R. , Hutton J. L.
Published: March 2003

Rationale, aims and objectives Within‐study selective reporting is widely believed to exist, although to date there have been no empirical studies to assess the extent of the problem in clinical research. The present study aimed to examine this process. Methods We undertook a pilot study, involving a single local research ethics committee (LREC), in which we compared the outcomes, analysis and sample size proposed in the original approved study protocol with the results presented in the subsequent study report. Results We received 41 (73%) replies from lead researchers of 56 projects, which were a complete cohort of clinical research applications approved in a particular time period by the LREC. Fifteen of these projects, which were completed and published at the time of our study, were further investigated. Only six (40%) stated which outcome variables were of primary interest and four (67%) of these showed consistency in the reports. Eight (53%) of the 15 studies mentioned an analysis plan. However, seven (88%) of these eight studies did not follow their prescribed analysis plan: the analysis of outcome variables or associations between certain variables were found to be missing from the report. Conclusions Our pilot study has shown that within‐study selective reporting may be examined qualitatively by comparing the study report with the study protocol. Our results suggest that it might well be substantial; however, the bias can only be broadly identified as protocols are not sufficiently precise.
Bayeswatch: an overview of Bayesian statistics
Authors: Austin Peter C. , Brunner Lawrence J. , Hux MD SM Janet E.
Published: March 2003

Increasingly, clinical research is evaluated on the quality of its statistical analysis. Traditionally, statistical analyses in clinical research have been carried out from a ‘frequentist’ perspective. The presence of an alternative paradigm – the Bayesian paradigm – has been relatively unknown in clinical research until recently. There is currently a growing interest in the use of Bayesian statistics in health care research. This is due both to a growing realization of the limitations of frequentist methods and to the ability of Bayesian methods explicitly to incorporate prior expert knowledge and belief into the analyses. This is in contrast to frequentist methods, where prior experience and beliefs tend to be incorporated into the analyses in an ad hoc fashion. This paper outlines the frequentist and Bayesian paradigms. Acute myocardial infarction mortality data are then analysed from both a Bayesian and a frequentist perspective. In some analyses, the two methods are seen to produce comparable results; in others, they produce different results. It is noted that in this example, there are clinically relevant questions that are more easily addressed from a Bayesian perspective. Finally, areas in clinical research where Bayesian ideas are increasingly common are highlighted.
Reflexivity and metapositions: strategies for appraisal of clinical evidence
Authors: Malterud Kirsti
Published: March 2003

According to Sackett, evidence‐based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. In this article, clinical reasoning is depicted as multilayered processes of evidence construction by means of social interaction and human interpretation. A basic set of knowledge is the doctor’s initial capital at the onset of the individual encounter. This is a necessary, but insufficient, presumption for the elaboration of clinical knowledge required to solve the particular problem. A diagnostic conclusion may appear to constitute the most obvious part of knowledge. Yet the formulation of hypotheses and the choice of adequate strategies for the pursuit of evidence are perhaps even more significant dimensions of clinical knowledge. Potential biases affect the ways in which evidence is gathered and used. When clinicians are not committed to appraising the evidence constituting the foundations of their enterprise, quality assessment of clinical practice becomes casual and unreliable. Reflexivity implies having a self‐conscious account of the production of knowledge as it is being produced. From metapositions, critical questions can be asked and sometimes answered. Evidence‐based practice in the original sense requires that doctors reflect upon their own positions as knowers, in the process of situated knowing, where certain rhetorical spaces rule.
Induced resistance in rainbow trout, Oncorhynchus mykiss (Walbaum), to gill disease associated with the microsporidian gill parasite Loma salmonae
Authors: Speare  , Beaman  , Jones  , Markham  , Arsenault
Published: March 2003

Branchial xenomas were detected by week 5 and disappeared by week 10 after naive juvenile rainbow trout, held at 14.5 °C, were fed or intubated with Loma salmonae‐infected gill tissue preparations. Upon re‐challenge with L. salmonae, these fish were protected from disease and branchial xenomas did not develop. Branchial xenomas were never detected in naive fish held at 10 °C and exposed to L. salmonae. When these fish were re‐challenged with L. salmonae at 14.5 °C, they were also protected from the disease. Branchial xenomas also developed after naive fish, held at 14.5 °C, were injected intraperitoneally with a semipurified preparation of fresh spores, but generally did not develop after intraperitoneal injection with a preparation of spores subjected to freezing and thawing before use. Fish that had received fresh spores intraperitoneally were completely resistant to disease when re‐challenged via oral delivery of spores, whereas those that had received frozen spores were incompletely, but significantly, protected from disease compared with naive fish. We conclude that infection with L. salmonae induces strong protection towards the disease upon re‐exposure to spores, and that the protection does not depend on the completion of the parasite's life cycle, thus establishing the basis for further research on vaccine development for this disease.
Identification and genetic characterization of yeasts isolated from freshwater prawns, Macrobrachium rosenbergii de Man, in Taiwan
Authors: Lu C C , Tang K F J , Chen S N
Published: March 2003

Since 1987, farmers in southern Taiwan have reported significant disease‐related mortalities in freshwater prawns. Most mortalities have occurred during the winter, and usually almost all the adult prawns die within 4–5 days after clinical signs appear. Histopathological studies show that cells in hepatopancreatic ducts and tubules are vacuolized and degenerated. Large numbers of membrane‐bound yeast aggregates are observed in the affected tissues. Two hundred and seventeen yeast isolates were obtained from diseased prawns, pond water and sediments from six areas. DNA restriction fragment length polymorphism (RFLP) was used to analyse the yeast genomes and to categorize them into five groups. Conventional biochemical and metabolic methods were then used to identify the yeasts of each group. The results showed that two strains of Candida sake (I and II), Pichia anomala, Endomyces fibuliger and Candida famata were present. In addition, the RAPD (random amplified polymorphic DNA) method was used to determine their genomic similarities. Two strains (I and II) of C. sake were the most similar (72%). C. sake I appears to be the primary causative agent of disease, based on frequencies of occurrence of the yeasts found in the diseased prawns.
Evaluation of florfenicol in Atlantic salmon, Salmo salar L.: efficacy against furunculosis due to Aeromonas salmonicida and cold water vibriosis due to Vibrio salmonicida
Authors: Nordmo  , Holth Riseth  , Varma  , Sutherland  , Brokken
Published: March 2003

Two replicated controlled trials were conducted to determine the efficacy of florfenicol against Aeromonas salmonicida and Vibrio salmonicida infections in Atlantic salmon, Salmo salar L., smolts kept in 25‰ salt water. Infection with A. salmonicida was treated with florfenicol, oxolinic acid, oxytetracycline, trimethoprim/sulphadiazine or flumequine, whereas the V. salmonicida infection was treated with florfenicol or oxolinic acid only. A. salmonicida infection was induced by the introduction of cohabitant fish previously inoculated intraperitoneally. Medication started simultaneously in all test tanks on the first day of specific mortality among test fish. V. salmonicida infection was induced by intraperitoneal inoculation of all test fish. Medication started 1 day after infection. Medicated feeds were produced by coating the antibacterials on standard feed pellets, and administered twice daily for 10 consecutive days. With the dose used in the present trials, florfenicol was highly effective in reducing specific mortalities due to both infections. It was slightly more effective than oxolinic acid and trimethoprim/sulphadiazine against A. salmonicida infection. There was no significant difference between florfenicol and oxolinic acid in reducing specific mortalities due to V. salmonicida.
Alterations in iron, zinc and major plasma proteins of rainbow trout, Oncorhynchus mykiss (Walbaum), and brook trout, Salvelinus fontinalis (Mitchill), with sterile peritonitis induced by oil‐adjuvanted multivalent bacterin vaccination
Authors: Simko E. , El‐Mowafi A. , Bettger W. J. , Ostland V. E. , Ferguson H. W. , Hayes M. A.
Published: March 2003

The early humoral responses of rainbow trout, Oncorhynchus mykiss (Walbaum), and brook trout, Salvelinus fontinalis (Mitchill), with sterile inflammation induced by intraperitoneal Lipogen Triple vaccination were compared to determine if genetic differences in susceptibility to furunculosis in salmonids correlated with different acute phase responses to vaccination. Similar severe acute sterile peritonitis occurred in response to Lipogen Triple in both species. Both species also had a rapid transient reduction in plasma iron concentration at 3 days. Moderate hypoferraemia persisted to day 14 in brook trout, but returned to normal by day 7 in rainbow trout. Plasma zinc decreased sharply 3 days after vaccination in rainbow trout and returned nearly to control levels by day 10; however, plasma zinc did not change in brook trout. Two‐dimensional sodium dodecyl sulphate polyacrylamide electrophoresis of plasma proteins revealed that increased amounts of a 48‐kDa protein group coincided with the hypoferraemic response in rainbow trout. In addition, a modest elevation in a 16‐kDa protein group also occurred in rainbow trout. These studies demonstrated the rapid changes in plasma iron in both species and mild elevation of two putative acute phase plasma proteins associated with vaccine‐induced inflammation in rainbow trout.
Vaccine development for winter ulcer disease, Vibrio viscosus, in Atlantic salmon, Salmo salar L.
Authors: Greger E. , Goodrich T.
Published: March 2003

Coldwater Vibrio species isolated from Atlantic salmon, Salmo salar L., during winter ulcer disease outbreaks at saltwater sites in Norway and Iceland were characterized phenotypically, tested for virulence, and used to evaluate the efficacy of multivalent, oil‐adjuvanted vaccines. The intraperitoneal (i.p.) injection of rainbow trout, Oncorhynchus mykiss (Walbaum), in fresh water with one bacteria species isolated during winter ulcer outbreaks, V. ‘viscosus’, produced rapid mortality and disease signs which resembled those observed during natural outbreaks [105 colony‐forming units (cfu) fish−−1]. Another species, V. ‘wodanis’, was not virulent to rainbow trout (103–106 cfu fish−−1). Although vaccination of rainbow trout with a mineral‐oil‐adjuvanted, injectable vaccine containing V. anguillarum (serotypes 01 and 02), V. salmonicida and Aeromonas salmonicida did not provide protection against injection challenge with V. viscosus, vaccines which included V. viscosus produced significant protection in Atlantic salmon and rainbow trout. Atlantic salmon vaccinated with an oil‐adjuvanted vaccine containing V. viscosus, V. wodanis and atypical A. salmonicida produced a relative percentage survival (RPS) of 97% when challenged i.p. with V. viscosus, demonstrating cross‐protection between strains from Iceland and Norway. Short‐term efficacy was demonstrated in rainbow trout by injection challenge at 21 and 43 days post‐vaccination with an oil‐adjuvanted vaccine containing V. viscosus, V. anguillarum (01/02), V. salmonicida and A. salmonicida, which produced an RPS of 96–99%. Rainbow trout challenged with V. viscosus at 52 and 362 days post‐vaccination produced an RPS of 93% and 79%, indicating that vaccination provided long‐term protection. In a similar manner, rainbow trout injected i.p. with 0.2 mL of a vaccine containing the five bacteria species and infectious pancreatic necrosis virus produced a 90% RPS when challenged with V. viscosus 66 days later. The high RPS under a severe challenge burden, along with disease signs in experimental freshwater challenges which resembled the saltwater disease condition, indicated that V. viscosus is a contributing factor to winter ulcer and that vaccination will protect against the disease.
Isolation and identification of Pseudoalteromonas piscicida strain Cura‐d associated with diseased damselfish (Pomacentridae) eggs
Authors: Nelson E. J. , Ghiorse W. C.
Published: March 2003

Bacteria were isolated from the diseased eggs of two damselfish (Pomacentridae) species, Amphiprion clarkii and Amblyglyphidodon curacao. Healthy A. clarkii eggs were infected separately with four bacterial isolates from the diseased eggs, as well as with Vibrio parahaemolyticus and Listonella anguillarum. Amphiprion clarkii eggs exposed to Cura‐d, an isolate from diseased A. curacao eggs, showed increased mortality compared to uninfected control eggs. The A. curacao eggs were infected separately with the same two isolates from diseased A. curacao eggs, and similarly, eggs exposed to isolate Cura‐d also showed increased mortality compared to uninfected eggs. However, the increase in mortality associated with exposure to isolate Cura‐d was most significant in A. clarkii eggs. A 16S rDNA comparative sequence analysis identified that isolate Cura‐d was most similar to Pseudoalteromonas piscicida, a known fish pathogen. Both Cura‐d and P. piscicida were found to be polarly flagellated, Gram‐negative rods with an oxidative metabolism which grew on d‐mannose, d‐fructose, sucrose and maltose, but not on l‐threonine. Based on these properties, it is proposed that Cura‐d should be classified as P. piscicida strain Cura‐d. It is concluded that the P. piscicida strain cura‐d was associated with the increased mortality observed in A. clarkii eggs.
Hepatoblastomas in the mummichog, Fundulus heteroclitus (L.), from a creosote‐contaminated environment: a histologic, ultrastructural and immunohistochemical study
Authors: Vogelbein W K. , Fournie J W. , Cooper P S. , Van Veld P A.
Published: March 2003

A detailed histologic, immunohistochemical and ultrastructural description of two cases of hepatoblastoma, a primitive liver cell neoplasm, is provided from mummichog, Fundulus heteroclitus (L.), inhabiting a creosote‐contaminated environment in the Elizabeth River, Virginia, USA. Both neoplasms were multifocal and comprised of undifferentiated embryonal cells with a high nuclear to cytoplasmic ratio. One case was characterized by a prominent macrotrabecular arrangement of tumour cells, whereas the other was solid in organization and undifferentiated. Tumour cells in some areas formed rosettes or pseudorosettes characteristic for hepatoblastoma. Focal areas within the macrotrabecular tumour were poorly differentiated, exhibiting a solid cellular arrangement. Strong immunolabelling with antibody C‐219 indicated elevation and altered patterns of P‐glycoprotein expression in both cases. In case 1, plasma membranes and tumour cell cytoplasm, but not bile canaliculi, were strongly labelled. However, in case 2, the macrotrabecular lesion, bile canaliculi were prominently labelled by the C‐219 antibody with only patchy immunolabelling of tumour cell cytoplasm. Ultrastructurally, neoplasms from both specimens were composed of small, closely apposed, undifferentiated embryonal cells with scant cytoplasm resembling developing hepatocytes. The macrotrabecular lesion (case 2) exhibited a prominent tubular organization with well‐developed bile canaliculi and constituent cells with abundant organelles. Based on histologic pattern, immunohistochemistry and ultrastructural features, these undifferentiated liver lesions are distinct from hepatocellular carcinoma reported in this species and warrant a diagnosis of hepatoblastoma.
Normal and aberrant tissue distribution of Loma salmonae (Microspora) within rainbow trout, Oncorhynchus mykiss (Walbaum), following experimental infection at water temperatures within and outside of the xenoma‐expression temperature boundaries
Authors: Sanchez J G , Speare D J , Markham R J F
Published: March 2003

Temperatures above 20 °C or below 9 °C interrupt the life cycle of the gill intracellular microsporidian parasite Loma salmonae (Microspora) prior to sporogony, inhibiting the production of xenomas. This study intended to characterize this life‐cycle failure. Juvenile rainbow trout, Oncorhynchus mykiss (Walbaum), were experimentally infected with L. salmonae spores, and the effect of water temperature on the progress of infection, as determined by polymerase chain reaction, was compared for fish held at water temperatures of 5, 15 and 21 °C. At 15 °C, parasite DNA was first detected in the heart (3 days post‐exposure [PE]), and then in the gills and spleen (2 weeks PE). Branchial xenomas developed by week 4 PE. In contrast, at 5 °C, the arrival of the parasite in the heart was delayed until 7 days PE. However, even though parasite DNA was detected in the gills at 7 days PE, xenomas failed to form in the gill, and by week 4 PE, parasite DNA was no longer detected. In fish held at 21 °C, parasite DNA was detected in the heart, gills and spleen by 3 days post‐infection, and similar results were observed at 7 days PE. Xenomas also failed to form in these fish and parasite DNA was no longer detected by week 2 PE. Within the range of temperatures tested in this study, spore germination and delivery of their DNA into the host through the intestinal wall was not blocked by temperature. At 5 or 21 °C, migration to the heart and gills occurred, but at aberrant periods of time. The normal life cycle of L. salmonae may depend on the completion of relatively lengthy, but yet unknown, stages of development within the heart, prior to reaching the gill. This development may be adversely affected by temperature, and explain the temperature limits of this parasite.
The physiological response of Atlantic salmon, Salmo salar L., to a single experimental challenge with sea lice, Lepeophtheirus salmonis
Authors: Bowers J M , Mustafa A , Speare D J , Conboy G A , Brimacombe M , Sims D E , Burka J F
Published: March 2003

The sea louse, Lepeophtheirus salmonis, is an ectoparasitic copepod of Atlantic salmon, Salmo salar L., capable of causing severe damage. This study was conducted to examine the physiological response of salmon to the stress of sea lice infestation. Smoltified salmon were acclimatized in 30‰ saltwater and exposed to high levels of lice infestation. The number of copepods per fish ranged from 15 to 285, with a mean of 106. The infested salmon were sampled six times over the 29‐d experimental duration and examined for alterations in the primary and secondary stress indicators, including plasma concentrations of cortisol, glucose, electrolytes, thyroid hormones T3 and T4, as well as the haematocrit level. The results were examined for correlations between the stress indicators, the number of copepods per fish and the life stage of the copepods. The presence of L. salmonis elevated stress indicators in relation to the specific sea lice stage. By day 21, both cortisol (mean 63.1 nmol L−1 controls: 179.8 nmol L−1 for parasitized) and glucose (mean 3.545 mmol L−1 controls: 4.567 mmol L−1 for parasitized) levels were significantly increased due to the presence of the lice. This was believed to be a direct result of the sea lice development into the larger life stages, thus increasing the level of host damage.
Evaluation of levamisole as a treatment for amoebic gill disease of Atlantic salmon, Salmo salar L.
Authors: Findlay V L , Zilberg D , Munday B L
Published: March 2003

Levamisole, a known T‐cell stimulator and immunomodulator in mammals, has been demonstrated to enhance resistance to amoebic gill disease in Atlantic salmon, Salmo salar L. When used in fresh water baths, dose rates of 1.25, 2.5 and 5 ppm levamisole stimulated resistance to reinfection with Paramoeba sp. that was evident from 2–3 weeks post‐treatment. It is proposed that this response is related to enhancement of the non‐specific immune system.
The production and characterization of monoclonal antibodies against Photobacterium damselae ssp. piscicida and initial observations using immunohistochemistry
Authors: Jung T S , Thompson K D , Morris D J , Adams A , Sneddon K
Published: March 2003

Five monoclonal antibodies (MAbs: F2B1, 1E4, 13B10, 4D4 and F3G12) were produced against lysed Photobacterium damselae ssp. piscicida (Ph. d. ssp. piscicida). The MAbs recognized three antigens of differing molecular weight on the Western blot of Ph. d. ssp. piscicida. They also cross‐reacted with five different species of Vibrio. An enzyme linked immunosorbent assay (ELISA) with MAbs, F3G12 and 4D4 demonstrated differences between Ph. d. ssp. piscicida and three Ph. d. ssp. damselae type strains, indicating differences in the surface antigenicity between these two groups of bacteria. Antigen retrieval in conjunction with immunohistochemistry (IHC) using MAb 13B10, revealed colonies of bacteria in the kidney, spleen and liver of sea bass, Dicentrarchus labrax, infected with pasteurellosis. A number of positive colonies were observed around the mucosal layers of the intestinal tissue, especially within the lamina propria. In addition, a number of bacterial colonies were associated with red blood cells and blood vessels of the organs examined.
Pathological findings in southern bluefin tuna, Thunnus maccoyii (Castelnau), infected with Cardicola forsteri (Cribb, Daintith & Munday, 2000) (Digenea: Sanguinicolidae), a blood fluke
Authors: Colquitt S E , Munday B L , Daintith M
Published: March 2003

Gills, heart ventricles and a limited number of other organs were collected from wild and captive southern bluefin tuna, and examined histologically for eggs of Cardicola forsteri. A limited number of entire hearts from farmed tuna were also examined, some of which yielded adult flukes within the ventricles. No adult flukes or their eggs were found in wild tuna. In infected farmed fish, fluke eggs impacted in the afferent filamentary blood vessels where they provoked a marked, but variable, inflammatory response, resulting in nodular gill lesions. No eggs were found on the efferent side of the gill vasculature, or in the compacta of the ventricle, which is supplied with blood from coronary vessels. The infection does not appear to cause mortality in farmed tuna.