bluuebunny/crossref_metadata_2025 huggingface dataset:
The
JAK2
V617F mutation occurs in hematopoietic stem cells in polycythemia vera and predisposes toward erythroid differentiation
Authors: Jamieson Catriona H. M. , Gotlib Jason , Durocher Jeffrey A. , Chao Mark P. , Mariappan M. Rajan , Lay Marla , Jones Carol , Zehnder James L. , Lilleberg Stan L. , Weissman Irving L.
Published: April 2006

Although a large proportion of patients with polycythemia vera (PV) harbor a valine-to-phenylalanine mutation at amino acid 617 (V617F) in the JAK2 signaling molecule, the stage of hematopoiesis at which the mutation arises is unknown. Here we isolated and characterized hematopoietic stem cells (HSC) and myeloid progenitors from 16 PV patient samples and 14 normal individuals, testing whether the JAK2 mutation could be found at the level of stem or progenitor cells and whether the
JAK2
V617F-positive cells had altered differentiation potential. In all PV samples analyzed, there were increased numbers of cells with a HSC phenotype (CD34
+
CD38
−
CD90
+
Lin
−
) compared with normal samples. Hematopoietic progenitor assays demonstrated that the differentiation potential of PV was already skewed toward the erythroid lineage at the HSC level. The
JAK2
V617F mutation was detectable within HSC and their progeny in PV. Moreover, the aberrant erythroid potential of PV HSC was potently inhibited with a JAK2 inhibitor, AG490.
Effects of chromium supplementation on selected metabolic responses in resting and exercising horses
Authors: Vervuert I , Cuddeford D , Coenen M
Published: April 2006

Chromium (Cr) is required for insulin function in the control of cellular glucose uptake. Other functions of Cr relate to its effects on growth, lipid metabolism, immune responses and interactions with nucleic acids. This study was conducted to obtain information on the effect of Cr supplementation on the metabolic responses of five exercising Standardbred horses. During the experiment, horses were fed every day for a 21-day period in a randomized order either a yeast product without Cr (control) or with 4.15 or 8.3 mg Cr day−1. Horses were exercised on a treadmill, alternating a work day of low-speed exercise at 5 m s−1 on a 3% incline for 45 min with a rest day. Each horse was adapted over a 21-day period to his or her respective supplementation before undergoing a standardized exercise test (SET). The SET comprised five incremental steps, each of 4 min duration, on a treadmill with a 3% incline; the first step was at 5 m s−1 and was followed with increments of 1 m s−1. Blood samples were taken for lactate, plasma glucose, serum insulin and cortisol estimation before, during and after each SET (30, 120 min and 24 h post-exercise). Blood Cr was estimated 2 h after feeding the control or Cr-enriched yeast (intake 8.3 mg Cr) in two horses. Heart rate was monitored throughout each SET. Blood lactate and plasma glucose peaks were highest at 8 and 9 m s−1 during the SET when 8.3 mg Cr was supplied. Serum insulin levels declined during the SET and there were no treatment-related changes. Twenty-four hours after exercise, plasma glucose and serum cortisol concentrations returned to basal levels or lower. Serum insulin rebounded 30 min after exercise but 24 h later, serum insulin concentrations were below resting levels. During the recovery period, Cr supplementation did not clearly affect metabolic responses. These results suggest that Cr supplementation had no beneficial effect in healthy, exercising horses.
Effect of seven common supplements on plasma electrolyte and total carbon dioxide concentration and strong ion difference in Standardbred horses subjected to a simulated race test
Authors: Szucsik Amanda , Baliskonis Valarie , McKeever Kenneth H
Published: April 2006

This study used a randomized crossover design, with investigators blind to the treatment given, to test the hypothesis that seven commercially available electrolyte supplements would alter plasma concentrations of Na+, K+, Cl−, lactate, total protein (TP) and total carbon dioxide (tCO2) as well as plasma strong ion difference (SID) and haematocrit (HCT). Ten unfit Standardbred mares (∼450 kg, 4–9 years) completed a series of simulated race exercise tests (SRT) during which venous blood was collected at five sampling intervals (prior to receiving electrolyte treatment, prior to the SRT, immediately following exercise and at 60 and 90 min post-SRT). Plasma electrolyte and tCO2concentrations were measured in duplicate using a Beckman EL-ISE electrolyte analyser. No difference (P>0.05) between treatments was detected at any of the five sampling intervals for plasma [Na+], [K+], [Cl−] or [tCO2]. Similarly, no significant difference was detected between treatments across each of the five sampling intervals for plasma SID, HCT or TP concentration. There were differences (P<0.05) in plasma [Na+], [K+] and [tCO2] (as well as plasma SID, HCT, and TP concentration) in the immediately post-SRT samples that were attributable to the physiological pressures associated with acute exercise. No differences (P>0.05) were detected between treatments across the pre-electrolyte and pre-SRT sampling intervals for plasma lactate concentration. There was, however, a significant time by treatment interaction during the 0, 60 and 90 min post-SRT sampling intervals for this parameter. The electrolyte supplements featured in this investigation did not affect either plasma tCO2concentration or SID; however, this result does not rule out the potential for other supplements, especially those containing alkalinizing ingredients, to exert an effect that could push a horse towards threshold values.
Lack of microalbuminuria in sled dogs following exercise
Authors: Durocher L , Hinchcliff K , Williamson K , McKenzie E , Holbrook T , Willard M , Royer C , Davis M
Published: April 2006

Humans undergoing intense exercise exhibit transient microalbuminuria. Previous studies have shown that swimming, but not running, induces microalbuminuria in dogs. In this study, urine samples were collected from nineteen well-conditioned Alaskan sled dogs and analysed by the Heska ERD-Screen Test for microalbuminuria. None of the dogs has microalbuminuria, indicated that well-trained dogs do not develop microalbuminuria after running. Further studies are needed to determine if these dogs do develop microalbuminuria after competition or longer-distane runs.
The effect of weighted boots on the movement of the back in the asymptomatic riding horse
Authors: Wennerstrand Josefine , Johnston Christopher , Rhodin Marie , Roethlisberger-Holm Karin , Drevemo Stig
Published: April 2006

Back dysfunction is an important reason for impaired performance in sport horses. Limb movements influence the movements of the back and factors affecting the limbs may therefore affect the movement of the back. The aim of the study was to investigate the influence of weighted boots on the fore- and hind limbs on the movement of the back. The back kinematics of eight horses was studied at the walk and trot on a treadmill. The ranges of movement (ROM) of the back were compared intra-individually, using Wilcoxon matched pairs test, when the horses moved with and without weighted boots on the fore- and hind limbs, respectively. Differences were considered significant atP<0.05. Weighted boots on the hind limbs increased the ROM for dorsoventral flexion and extension in the lumbar back at the walk and decreased the ROM for lateral bending at the thoracolumbar junction at the trot. Weighted boots on the forelimbs decreased the ROM for lateral bending at the withers at the trot. Knowledge of the effect of weighted boots on the back movement is useful in training and rehabilitation of sport horses. Weighted boots on the hind limbs at the walk may induce strengthening of the flexors of the lumbar back and increase the flexion–extension of the lumbar back under controlled conditions.
ALCOHOL ADVERTISING IN MAGAZINES: DO BEER, WINE, AND SPIRITS ADS TARGET YOUTH?
Authors: NELSON JON P.
Published: April 2006

In 2003, the alcohol beverage industry spent more than $1.6 billion on advertising, including $394 million on ads in magazines. Critics allege that these activities target adolescents. This article examines count data for alcohol ads placed in 28 magazines in 2001–03. Specifying a demand function for advertising space, regressions are estimated that are conditioned on magazine characteristics and readership demographics, including the percent of youth in the audience. The explanatory variables include real prices of advertisements and audience size. Results indicate significant effects for price, audience size, and adult demographics, but fail to support claims that advertisers target youth. (JEL L82, L66, M37)
Promoter Shuffling at a Nuclear Gene for Mitochondrial RPL27. Involvement of Interchromosome and Subsequent Intrachromosome Recombinations
Authors: Ueda Minoru , Arimura Shin-ichi , Yamamoto Masayuki P. , Takaiwa Fumio , Tsutsumi Nobuhiro , Kadowaki Koh-ichi
Published: April 2006

The Reclinomonas americana mitochondrial genome contains a mitochondrial ribosomal protein L27 (rpl27) gene, whereas the rpl27 gene is absent from all plant mitochondrial genomes examined to date. This suggests that plant mitochondrial rpl27 genes have been transferred previously from the mitochondrial genome to the nuclear genome. A nuclear cDNA encoding mitochondrial RPL27 was identified in rice (Oryza sativa). Three similar sequences were identified: rpl27-1 and rpl27-2 on chromosome 8 and rpl27-3 on chromosome 4. Harr plot analysis suggests that they were generated by inter- and intrachromosomal duplications. Interestingly, the transcribed rpl27 gene (rpl27-1) acquired a promoter sequence that was derived from the rice spt16 (Osspt16) gene, the homolog of a global transcription factor in yeast (Saccharomyces cerevisiae) located downstream from the rpl27-3 sequence on chromosome 4, after inter- and intrachromosomal recombination. Reverse transcription-PCR and promoter assay revealed that the rpl27 mRNAs were mainly transcribed from rpl27-1. A repeat of seven nucleotides (AATAGTT) was identified at the junction of rpl27-1 and rpl27-2 on chromosome 8, and the same repeat was also identified at the 5′ end of rpl27-2 and the 3′ end of rpl27-1. This repeat (AATAGTT) contains the hot-spot sequence AGTT, which is preferentially recognized by topoisomerase I in wheat (Triticum aestivum) germ, suggesting the involvement of topoisomerase I in this recombination. We here report the example of promoter shuffling and show that this promoter shuffling resulted from a recent segmental duplication through inter- and intrachromosomal recombination events.
Arabidopsis INOSITOL TRANSPORTER4 Mediates High-Affinity H+ Symport of Myoinositol across the Plasma Membrane
Authors: Schneider Sabine , Schneidereit Alexander , Konrad Kai R. , Hajirezaei Mohammad-Reza , Gramann Monika , Hedrich Rainer , Sauer Norbert
Published: April 2006

Four genes of the Arabidopsis (Arabidopsis thaliana) monosaccharide transporter-like superfamily share significant homology with transporter genes previously identified in the common ice plant (Mesembryanthemum crystallinum), a model system for studies on salt tolerance of higher plants. These ice plant transporters had been discussed as tonoplast proteins catalyzing the inositol-dependent efflux of Na+ ions from vacuoles. The subcellular localization and the physiological role of the homologous proteins in the glycophyte Arabidopsis were unclear. Here we describe Arabidopsis INOSITOL TRANSPORTER4 (AtINT4), the first member of this subgroup of Arabidopsis monosaccharide transporter-like transporters. Functional analyses of the protein in yeast (Saccharomyces cerevisiae) and Xenopus laevis oocytes characterize this protein as a highly specific H+ symporter for myoinositol. These activities and analyses of the subcellular localization of an AtINT4 fusion protein in Arabidopsis and tobacco (Nicotiana tabacum) reveal that AtINT4 is located in the plasma membrane. AtINT4 promoter-reporter gene plants demonstrate that AtINT4 is strongly expressed in Arabidopsis pollen and phloem companion cells. The potential physiological role of AtINT4 is discussed.
Response of the Leaf Cell Wall to Desiccation in the Resurrection Plant Myrothamnus flabellifolius
Authors: Moore John P. , Nguema-Ona Eric , Chevalier Laurence , Lindsey George G. , Brandt Wolf F. , Lerouge Patrice , Farrant Jill M. , Driouich Azeddine
Published: April 2006

The Myrothamnus flabellifolius leaf cell wall and its response to desiccation were investigated using electron microscopic, biochemical, and immunocytochemical techniques. Electron microscopy revealed desiccation-induced cell wall folding in the majority of mesophyll and epidermal cells. Thick-walled vascular tissue and sclerenchymous ribs did not fold and supported the surrounding tissue, thereby limiting the extent of leaf shrinkage and allowing leaf morphology to be rapidly regained upon rehydration. Isolated cell walls from hydrated and desiccated M. flabellifolius leaves were fractionated into their constituent polymers and the resulting fractions were analyzed for monosaccharide content. Significant differences between hydrated and desiccated states were observed in the water-soluble buffer extract, pectin fractions, and the arabinogalactan protein-rich extract. A marked increase in galacturonic acid was found in the alkali-insoluble pectic fraction. Xyloglucan structure was analyzed and shown to be of the standard dicotyledonous pattern. Immunocytochemical analysis determined the cellular location of the various epitopes associated with cell wall components, including pectin, xyloglucan, and arabinogalactan proteins, in hydrated and desiccated leaf tissue. The most striking observation was a constitutively present high concentration of arabinose, which was associated with pectin, presumably in the form of arabinan polymers. We propose that the arabinan-rich leaf cell wall of M. flabellifolius possesses the necessary structural properties to be able to undergo repeated periods of desiccation and rehydration.
Nitric Oxide- and Hydrogen Peroxide-Responsive Gene Regulation during Cell Death Induction in Tobacco
Authors: Zago Elisa , Morsa Stijn , Dat James F. , Alard Philippe , Ferrarini Alberto , Inzé Dirk , Delledonne Massimo , Van Breusegem Frank
Published: April 2006

Nitric oxide (NO) and hydrogen peroxide (H2O2) are regulatory molecules in various developmental processes and stress responses. Tobacco (Nicotiana tabacum) leaves exposed to moderate high light dramatically potentiated NO-mediated cell death in catalase-deficient (CAT1AS) but not in wild-type plants, providing genetic evidence for a partnership between NO and H2O2 during the induction of programmed cell death. With this experimental model system, the specific impact on gene expression was characterized by either NO or H2O2 alone or both molecules combined. By means of genome-wide cDNA-amplified fragment length polymorphism analysis, transcriptional changes were compared in high light-treated CAT1AS and wild-type leaves treated with or without the NO donor sodium nitroprusside. Differential gene expression was detected for 214 of the approximately 8,000 transcript fragments examined. For 108 fragments, sequence analysis revealed homology to genes with a role in signal transduction, defense response, hormone interplay, proteolysis, transport, and metabolism. Surprisingly, only 16 genes were specifically induced by the combined action of NO and H2O2, whereas the majority were regulated by either of them alone. At least seven transcription factors were mutually up-regulated, indicating significant overlap between NO and H2O2 signaling pathways. These results consolidate significant cross-talk between NO and H2O2, provide new insight into the early transcriptional response of plants to increased NO and H2O2 levels, and identify target genes of the combined action of NO and H2O2 during the induction of plant cell death.
Transcription Analysis of Arabidopsis Membrane Transporters and Hormone Pathways during Developmental and Induced Leaf Senescence
Authors: van der Graaff Eric , Schwacke Rainer , Schneider Anja , Desimone Marcelo , Flügge Ulf-Ingo , Kunze Reinhard
Published: April 2006

A comparative transcriptome analysis for successive stages of Arabidopsis (Arabidopsis thaliana) developmental leaf senescence (NS), darkening-induced senescence of individual leaves attached to the plant (DIS), and senescence in dark-incubated detached leaves (DET) revealed many novel senescence-associated genes with distinct expression profiles. The three senescence processes share a high number of regulated genes, although the overall number of regulated genes during DIS and DET is about 2 times lower than during NS. Consequently, the number of NS-specific genes is much higher than the number of DIS- or DET-specific genes. The expression profiles of transporters (TPs), receptor-like kinases, autophagy genes, and hormone pathways were analyzed in detail. The Arabidopsis TPs and other integral membrane proteins were systematically reclassified based on the Transporter Classification system. Coordinate activation or inactivation of several genes is observed in some TP families in all three or only in individual senescence types, indicating differences in the genetic programs for remobilization of catabolites. Characteristic senescence type-specific differences were also apparent in the expression profiles of (putative) signaling kinases. For eight hormones, the expression of biosynthesis, metabolism, signaling, and (partially) response genes was investigated. In most pathways, novel senescence-associated genes were identified. The expression profiles of hormone homeostasis and signaling genes reveal additional players in the senescence regulatory network.
Physical and Functional Interactions between Pathogen-Induced Arabidopsis WRKY18, WRKY40, and WRKY60 Transcription Factors
Authors: Xu Xinping , Chen Chunhong , Fan Baofang , Chen Zhixiang
Published: April 2006

Limited information is available about the roles of specific WRKY transcription factors in plant defense. We report physical and functional interactions between structurally related and pathogen-induced WRKY18, WRKY40, and WRKY60 transcription factors in Arabidopsis  thaliana. The three WRKY proteins formed both homocomplexes and heterocomplexes and DNA binding activities were significantly shifted depending on which WRKY proteins were present in these complexes. Single WRKY mutants exhibited no or small alterations in response to the hemibiotrophic bacterial pathogen Pseudomonas syringae and the necrotrophic fungal pathogen Botrytis cinerea. However, wrky18 wrky40 and wrky18 wrky60 double mutants and the wrky18 wrky40 wrky60 triple mutant were substantially more resistant to P. syringae but more susceptible to B. cinerea than wild-type plants. Thus, the three WRKY proteins have partially redundant roles in plant responses to the two distinct types of pathogens, with WRKY18 playing a more important role than the other two. The contrasting responses of these WRKY mutants to the two pathogens correlated with opposite effects on pathogen-induced expression of salicylic acid–regulated PATHOGENESIS-RELATED1 and jasmonic acid–regulated PDF1.2. While constitutive expression of WRKY18 enhanced resistance to P. syringae, its coexpression with WRKY40 or WRKY60 made plants more susceptible to both P. syringae and B. cinerea. These results indicate that the three WRKY proteins interact both physically and functionally in a complex pattern of overlapping, antagonistic, and distinct roles in plant responses to different types of microbial pathogens.
γ-Tubulin Is Essential for Acentrosomal Microtubule Nucleation and Coordination of Late Mitotic Events inArabidopsis
Authors: Binarová Pavla , Cenklová Věra , Procházková Jiřina , Doskočilová Anna , Volc Jindřich , Vrlík Martin , Bögre László
Published: April 2006

γ-Tubulin is required for microtubule (MT) nucleation at MT organizing centers such as centrosomes or spindle pole bodies, but little is known about its noncentrosomal functions. We conditionally downregulated γ-tubulin by inducible expression of RNA interference (RNAi) constructs in Arabidopsis thaliana. Almost complete RNAi depletion of γ-tubulin led to the absence of MTs and was lethal at the cotyledon stage. After induction of RNAi expression, γ-tubulin was gradually depleted from both cytoplasmic and microsomal fractions. In RNAi plants with partial loss of γ-tubulin, MT recovery after drug-induced depolymerization was impaired. Similarly, immunodepletion of γ-tubulin from Arabidopsis extracts severely compromised in vitro polymerization of MTs. Reduction of γ-tubulin protein levels led to randomization and bundling of cortical MTs. This finding indicates that MT-bound γ-tubulin is part of a cortical template guiding the microtubular network and is essential for MT nucleation. Furthermore, we found that cells with decreased levels of γ-tubulin could progress through mitosis, but cytokinesis was strongly affected. Stepwise diminution of γ-tubulin allowed us to reveal roles for MT nucleation in plant development, such as organization of cell files, anisotropic and polar tip growth, and stomatal patterning. Some of these functions of γ-tubulin might be independent of MT nucleation.
Dynamic and Compensatory Responses ofArabidopsisShoot and Floral Meristems toCLV3Signaling
Authors: Müller Ralf , Borghi Lorenzo , Kwiatkowska Dorota , Laufs Patrick , Simon Rüdiger
Published: April 2006

In Arabidopsis thaliana, the stem cell population of the shoot system is controlled by regulatory circuitry involving the WUSCHEL (WUS) and CLAVATA (CLV1-3) genes. WUS signals from the organizing center (OC) to promote stem cell fate at the meristem apex. Stem cells express the secreted peptide CLV3 that activates a signal transduction cascade to restrict WUS expression, thus providing a feedback mechanism. Stem cell homeostasis is proposed to be achieved by balancing these signals. We tested the dynamics of CLV3 signaling using an inducible gene expression system. We show here that increasing the CLV3 signal can very rapidly repress WUS expression during development, which in turn causes a fast reduction of CLV3 expression. We demonstrate that increased CLV3 signaling restricts meristem growth and promotes allocation of peripheral meristem cells into organ primordia. In addition, we extend the current model for stem cell control by showing that meristem homeostasis tolerates variation in CLV3 levels over a 10-fold range and that high-level CLV3 signaling can be partially compensated with time, indicating that the level of CLV3 expression communicates only limited information on stem cell number to the underlying OC cells.
Endogenous and Synthetic MicroRNAs Stimulate Simultaneous, Efficient, and Localized Regulation of Multiple Targets in Diverse Species
Authors: Alvarez John Paul , Pekker Irena , Goldshmidt Alexander , Blum Eyal , Amsellem Ziva , Eshed Yuval
Published: April 2006

Recent studies demonstrated that pattern formation in plants involves regulation of transcription factor families by microRNAs (miRNAs). To explore the potency, autonomy, target range, and functional conservation of miRNA genes, a systematic comparison between plants ectopically expressing pre-miRNAs and plants with corresponding multiple mutant combinations of target genes was performed. We show that regulated expression of several Arabidopsis thaliana pre-miRNA genes induced a range of phenotypic alterations, the most extreme ones being a phenocopy of combined loss of their predicted target genes. This result indicates quantitative regulation by miRNA as a potential source for diversity in developmental outcomes. Remarkably, custom-made, synthetic miRNAs vectored by endogenous pre-miRNA backbones also produced phenocopies of multiple mutant combinations of genes that are not naturally regulated by miRNA. Arabidopsis-based endogenous and synthetic pre-miRNAs were also processed effectively in tomato (Solanum lycopersicum) and tobacco (Nicotiana tabacum). Synthetic miR-ARF targeting Auxin Response Factors 2, 3, and 4 induced dramatic transformations of abaxial tissues into adaxial ones in all three species, which could not cross graft joints. Likewise, organ-specific expression of miR165b that coregulates the PHABULOSA-like adaxial identity genes induced localized abaxial transformations. Thus, miRNAs provide a flexible, quantitative, and autonomous platform that can be employed for regulated expression of multiple related genes in diverse species.
Epizootic haematopoietic necrosis virus: purification and classification
Authors: EATON B. T. , HYATT A. D. , HENGSTBERGER S.
Published: April 2006

Abstract. Epizootic haematopoietic necrosis virus (EHNV) has been isolated from redfin perch, Perca fluviatilis L., and cultured rainbow trout, Oncorhynchus mykiss (Walbaum), in Victoria and New South Wales, Australia. On the basis of virion size, icosahedral morphology and ultrastructural characteristics of virus‐infected cells, EHNV was designated as an iridovirus. The following observations outlined in this paper confirm the designation: (1) The number and complexity of proteins in purified EHNV and the ordered appearance of virus‐specific proteins in infected cells are similar to that described for the iridovirus, frog virus 3 (FV3). (2) EHNV isolated from the cytoplasm of infected cells contains a lipid membrane associated with 7–9 nm capsomeric subunits containing a 52‐kD protein. (3) The morphogenesis of EHNV within cytoplasmic inclusion bodies resembles that of FV3 and a piscine iridovirus isolated from goldfish, Carassius auratus (L.) (4) EHNV also resembles FV3 in its association with the cytoskeleton of infected cells. (5) EHNV DNA, like that of other iridoviruses, is resistant to digestion with HpaII, a restriction endonuclease which does not cleave DNA at CCGG sequences where the internal cytosine is methylated.
Proteases of theAeromonas hydrophilacomplex: identification, characterization and relation to virulence in channel catfish,Ictalurus punctatus(Rafinesque)
Authors: CHABOT D. J. , THUNE R. L.
Published: April 2006

Abstract.Traditional biochemieal techniques and a stain to detect proteases in polyacrylamide gels were used to identify and partially characterize three proteases, P1, P2 and P3, produced byAeromonas hydrophilastrain Ah 22. P1 was found to be a heat‐labile serine protease with an optimum pH of 7·5, while P2 is a heat‐stable metalloprotease with an optimum pH of 8·0, and P3 is a moderately heat‐stable metalloprotease with peak activity beween pH 7 and 11. A comparison of 17 other strains of theA. hydrophilacomplex indicated that four produced P1, P2 and P3. Two strains produced just P1 and P3; one produced only P3; six produced two different serine proteases, P2a and P2b; and two produced a number of uncharacterized proteases. Virulence studies in age‐0 + channel catfish indicated no correlation between either quantitative or qualitative protease production and virulence.
Vaccination experiments and studies of the humoral immune responses in cod, Gadus morhua L., to four strains of monoclonal‐defined Vibrio anguillarum
Authors: ESPELID S. , RØDSETH O. M. , JØRGENSEN T. Ø.
Published: April 2006

Abstract. Vibrio anguillarum isolated from diseased cod, Gadus morhua L., were serotyped by use of a panel of monoclonal antibodies. Four serotypes could be distinguished, having different lipopolysaccharide determinants. These phenotypic differences were also reflected in the genetic map, as revealed by fingerprinting of bacterial DNA. Antisera were raised in cod after immunization with the V. anguillarum serotypes, and Western blot techniques demonstrated production of specific antibodies mainly to LPS‐antigens. The immune system in cod discriminates to a eertain degree between the four serotypes as shown by crossreactions of the immune sera in elisa. Moreover, it was also shown that natural antibodies to bacterial antigens are present in non‐immune sera, but these specificities are non‐LPS in nature. As a consequence of the heterogeneity of the V. anguillarum strains, vaccination experiments were performed under laboratory conditions to compare the effectiveness of bacterins based on either single vaccines or polyvaccines. The results from these experiments were promising since challenge with one strain demonstrated 100% protection both in fish vaccinated with the homologous serotype as well as a mixture of all the four serotypes.
Commensal bacteria and their possible relationship to the mortahty of incubating salmonid eggs
Authors: BARKER G. A. , SMITH S. N. , BROMAGE N. R.
Published: April 2006

Abstract. Eggs of female rainbow trout, Oncorhynchus mykiss (Walbaum), were fertilized and subsequently exposed to high eoncentrations of Pseudomonas fluorescens or Cytophaga sp. (106 cells/ml) for 45 min during water hardening. Eggs were placed in horizontal hatchery trays alongside sterile water‐treated eggs and mortality rates were observed daily throughout incubation. Numbers and species of bacteria present on egg surfaces and within egg contents were monitored at the green stage (unfertilized), after hardening, and at 12h, 7 days, 14 days, 21 days and 28 days incubation. Surfaces of the incubating eggs of all groups, irrespective of treatment at water hardening, were eventually colonized by considerable numbers of Cytophaga sp., P. fluorescens and to a lesser extent Pseudomonas sp. and Aeromonas hydrophila. Few bacteria were recovered from inside eggs. Overall, no correlation was found between bacteria on the egg surface and egg death. However, a significantly higher ‘rate’ of egg death during early stages of incubation was found amongst eggs exposed to P. fluorescens at water hardening. Thus, high numbers of P. fluorescens on egg surfaces during initial stages of incubation might pose a potential threat to egg survival. Therefore, it is suggested that strenuous efforts are made at time of hardening to obtain the purest available source of water.
The process of infection, migration, growth and development of Sanguinicola inermis Plehn, 1905 (Digenea: Sanguinicolidae) in carp, Cyprinus carpio L.
Authors: SOMMERVILLE C. , IQBAL N. A. M.
Published: April 2006

Abstract. Sanguinicoliasis is a serious disease of cultured carp causing high mortality in early fry. Experimental infections were used to study the pattern of penetration, and subsequent behaviour and development of the parasite. Maximum penetration of cercariae was achieved within 30 min, followed by a period of rapid development and growth marked by a doubling in length within the first 12 h. Subsequent growth was slower, during which major organ development took place, with gonadal maturity being completed between 60 and 90 days p.i. Penetration occurred mainly through the fins, particularly the caudal fin, and large numbers of worms remained in the skin where they continued to develop to maturity. A small proportion of the worms were found in the heart and gill vessels soon after infection. However, migration from the skin began at 60 days p.i. and greater numbers (57%) of the worms were found in heart and gill vessels at 90 days, coinciding with onset of egg production. Decline in worm numbers in the gill/heart region began after 120 days. Gill/heart worms differed in a number of features from skin worms, but egg production occurred simultaneously in both sites.
Heterogeneity of extracellular proteases produced by different isolates ofAeromonas hydrophilaandA. sobriapathogenic for fish
Authors: NIETO T. P. , ELLIS A. E.
Published: April 2006

Abstract.Ten isolates ofAeromonas hydrophilaand two ofA. sobriawere investigated with regard to elastase and caseinase production, and the pI, heat and EDTA sensitivity of extracellular caseinase enzymes. An extreme degree of heterogeneity amongst the strains was observed. In isoelectricfocusing, the ECP of the various strains possessed between 19 and 31 proteins, and the number of extracellular proteases ranged from one to 12. Similarities between strains using one criterion of comparison (e.g. IEF patterns) did not hold true by other criteria (e.g. heat or EDTA sensitivity of proteases).
Coccidiosis due to Goussia lomi (Protista: Apicomplexa) in aquarium‐reared Murray cod, Maccullochella peeli (Mitchell), (Percichthyidae)
Authors: PHILBEY A. W. , INGRAM B. A.
Published: April 2006

Abstract. Intestinal parasitism by the coccidian Goussia lomi was associated with morbidity and histological lesions in aquarium‐reared Murray cod fry, Maccullochella peeli (Mitchell), at a hatchery near Narrandera, New South Wales, Australia. Coccidial infection was not found in pond‐reared Murray cod of the same age, nor in trout cod, M. macquariensis (Cuvier & Valenciennes), reared under similar conditions at the same hatchery. Overcrowding may have predisposed Murray cod in aquaria to heavy infection with G. lomi. Clinical coccidiosis was expressed in a small proportion of infected fish. Large numbers of coccidial developmental forms were detected histologically in the intestinal mucosa of affected fish in association with a necrotic enteropathy. Using a method of intestinal trypsin digestion and flotation, 2000 coccidial oocysts were counted in one 0‐05g fish.
Humoral immune response in Atlantic salmon, Salmo salar L., to cellular and extracellular antigens of Aeromonas salmonicida
Authors: LUND V. , JØRGENSEN T. , HOLM K. O. , EGGSET G.
Published: April 2006

Abstract. The putative virulence factors of Aeromonas salmonicida, the aetiological agent of furunculosis in salmonids, are candidates for protective antigens in effective vaeeines against furunculosis. In this report, the authors have compared the immunogenieily of eell‐associated and extracellular antigens of A. salmonicida in Atlantic salmon, Salmo salar L., to that in rabbit. The animals were immunized with formalin‐killed whole cells and formalin‐inactivated extracellular products (ECP), either separately or in combination. The ability of the antigens to induce antibody production was studied by elisa and Western blotting techniques. These results confirm previous reports that far more structures are immunogenie in rabbit compared to the antibody responses elicited in salmon. However, in both species, some antigens were dominant, including a caseinolytic protease in addition to the A‐protein and high and low MW LPS.
The role of the lethal extracellular cytolysin of Aeromonas salmonicida in the pathology of furunculosis
Authors: LEE K.‐K. , ELLIS A. E.
Published: April 2006

Abstract. The histopathological effects of intramuscular (i.m.) and intraperitoneal injections of the purified lethal cytolytic toxin of A. salmonicida in Atlantic salmon, Salmo salar L., were restricted to extensive degranulation of eosinophilic granular cells (EGCs) in the gills (both routes) and a limited coagulative necrosis of muscle fibres at the site of i.m. injection. The severity of these lesions did not apparently differ amongst fish that were moribund within 48 h and the surviving fish at 90 h. Previous studies indicate a maximum time to death caused by this toxin of 48 h. Thus, it is difficult to account for death of the fish from the toxin solely on the grounds of the histopathological features. It is suggested that a complex metabolic dysfunction results in death. The mechanism of ‘furuncle’ formation was demonstrated to result from a combined effect of the cytolysin and the purified 70‐kDa protease present in the ECP. When i.m.‐injected singly, the purified cytolysin produced a limited coagulative necrosis and the purified protease produced a limited liquefaction and haemorrhaging. In combination, they induced the extensive liquefactive haemorrhagic ‘furuncle’ characteristic of the whole ECP.
Susceptibility of salmonid erythrocytes to lysis by bacterial lipopolysaccharides
Authors: LEE K.‐K. , ELLIS A. E.
Published: April 2006

Abstract. Bacterial lipopolysaccharide (LPS) is known to have binding affinity for mammalian erythrocyte membranes but does not cause haemolysis. In this study, LPS from eight different bacterial species all possessed haemolytic activity for salmonid erythrocytes. There were some differences in haemolytic activity among the different bacterial LPS after 2 h incubation. Lytic titres continued to increase with time for some LPS species reaching extremely high litres after 20 h incubation for the Salmonella minnesota LPS. The LPS extracted by the hot‐phenol method from extracellular products (ECP) of Aeromonas salmonicida was more haemolytic than that extracted from the bacterial cell walls. Separated lipid A‐ and O‐antigen fractions of A. salmonicida LPS had a similar low haemolytic activity. When A. salmonicida LPS, lipid A‐ and O‐antigen were pre‐incubated with bovine serum albumin, only LPS extracted from ECP retained any haemolytic activity. The LPS types used in this study were not haemolytic for rabbit erythrocytes.
Carrier state in furunculosis: secondary infection of trout with different Aeromonas salmonicida strains results in advantage for the primarily harboured one
Authors: MICHEL C. , FAIVRE B.
Published: April 2006

Abstract. On the basis of previous observations, in vivo experiments were conducted in rainbow trout, Oncorhynchus mykiss (Walbaum), to detect possible competition between strains of Aeromonas salmonicida differing in their pattern of resistance to antimicrobial drugs. Serial infections, or reinfection of naturally‐infected trout, were induced by intramuscular injection. Surviving fish were artificially stressed, and all dying fish were examined using selective media to assess the type of latent infection. Secondary infections with virulent strains always resulted in mortality and reisolation of the secondary strain in pure culture. However, when trout having undergone the two successive infections were stressed, the primary strain was always reisolated. Primary strains seem to be able to survive in unknown locations within cells or tissues, regardless of their virulence or growth potency. Although a protective effect conferred by latent infection to secondary challenge could not be clearly proven, such mechanisms resemble what occurs in premunition and could be of epidemiological interest.
Polysaccharide‐induced protection of carp, Cyprinus carpio L., against bacterial infection
Authors: YANO T. , MATSUYAMA H. , MANGINDAAN R. E. P.
Published: April 2006

Abstract. The efficacy of 10 polysaccharides (curdlan, inulin, krestin, laminaran, lentinan, levan, schizophylian, selerogiucan, yeast glucan and zymosan) to enhance protection of carp, Cyprinus carpio L., against bacterial infection was investigated. Carp were intraperitoneally injected with the polysaceharides (2–l0 mgkg‐1) on days 1 and 4, and challenged with Edwardsiella tarda on day 7. Among the polysaccharides tested, lentinan, schizophyllan and scleroglucan, which are l,6‐branchcd‐β‐l,3‐glucans, significantly increased the survival rate. They also induced a protective effect against Aeromonas hydrophila at a dose of 5 mg kg‐1. The ability of the polysaccharides to activate the alternative complement pathway (ACP) was examined by incubating the polysaccharides with carp serum and measuring the residual ACP activity. At a final concentration of 0.l mgml‐1, l,6‐branched‐β‐1,3‐glucans greatly reduced (76–77%) the ACP activity. Therefore, it is suggested that the protective effect of the l,6‐branched‐β‐1,3‐glucans may be associated with the activation of ACP.
The occurrence of proliferative kidney disease (PKD) in cultured and wild fish: further investigations
Authors: BUCKE D. , FEIST S. W. , CLIFTON‐HADLEY R. S.
Published: April 2006

Abstract. In an investigation of the occurrence of proliferative kidney disease (PKD) in freshwater fish other than rainbow trout, 18 species of wild fish and seven species of fish raised in cultivation wore sampled from waters where the disease occurred annually in rainbow trout, Oncorhynchus mykiss (Richardson). Results revealed that certain wild stocks of brown trout. Salmo trutta L., grayling, Thymallus thymallus L., and pike, Esox lucius L., were infected with PKD, as were cultivated Atlantic salmon, Salmo salar L., parr, brown trout and char, Salvelinus alpinus (L.). Microscopical examination revealed the presence of the PKX cell in these species and also intraluminal protozoa possibly related to the PKX cell, which were not found in the rainbow trout. Other species of freshwater fish had myxosporidan infections but, unlike PKD infection, there was little host/parasite tissue response. The PKX cell as a myxosporidan stage is discussed and the presence of the disease in wild fish is reported.
Epizootic haematopoietic necrosis virus: detection by ELISA, immunohistochemistry and immunoelectron‐microscopy
Authors: HYATT A. D. , EATON B. T. , HENGSTBERGER S. , RUSSEL G.
Published: April 2006

Abstract. Epizootic haematopoietic necrosis virus (EHNV) was isolated from cultured rainbow trout, Oncorhynchus mykiss (Walbaum). Antibodies to the virus and to associated capsid subunits have been produced and used in immunohistochemistry, immunoelectron‐microscopy and an antigcn‐capture‐immunosorbent assay (ELISA). The results show that both antibodies can be used by various immuno‐procedures to detect both redfin perch, Perca ftuviatilis L., and rainbow trout isolates of EHNV. The procedures described provide for the first time rapid and specific tests for the detection of EHNV in cultured and clinical material.
Description of Vavraia parastacida sp. nov. (Microspora: Pleistophoridae) from marron, Cherax tenuimanus (Smith), (Decapoda: Parastacidae)
Authors: LANGDON J. S.
Published: April 2006

Abstract. A plcistophorid microsporidian is described from marron, Cherax tenuimanus (Smith). The parasite is polysporous, forming eight, 16, 32 or 64 ovoid spores in persistent, two‐layered mcrontogcnctic sporophorous vesicles. Nuclei remain isolated throughout merogony and sporogony. The sporophorous vesicle forms from the amorphous coat surrounding meronts, which thickens and condenses into two layers during sporogony. The parasite is placed in Vavraia Weiser, 1977, and named Vavraia parastacida sp. nov.
Fluoroquinolones display rapid bactericidal activity and low mutation frequencies against Aeromonas salmonicida
Authors: BARNES A. C. , AMYES S. G. B. , HASTINGS T. S. , LEWIN C. S.
Published: April 2006

Abstract. Oxolinic acid and five new fluoroquinolones, sarafloxacin, enrofloxacin, PD127, 391, PD117, 596 and C1934, were evaluated for in vitro activity against Aeromonas salmonicida. Sarafloxacin, enrofloxacin, PD127, 391 and PD117, 596 were significantly more active than cither oxolinic acid or C1934 in terms of their bactericidal activity against both oxolinic‐acid‐resistant and sensitive strains of A. salmonicida, killing 99% of the bacteria after 1h exposure. Resistant mutants developed at lower frequency to the fluoroquinolones than to oxolinic acid or oxytctracycline at 5, 10 and 20 times the MIC. However, mutants selected with one quinolone were cross‐resistant to all the other quinolones tested.
Use of an ELISA‐based assay for the detection of antibody‐secreting cells in channel catfish, Ictalurus punctatus (Rafinesque)
Authors: WATERSTRAT P. R. , BRAZIL J. , AINSWORTH A. J.
Published: April 2006

Abstract. An ELISA‐bascd plaque assay for the detection and quantification of antibody‐secreting cells has been adapted for use in fish. The assay involves incubating catfish lymphocytes in 24‐well plates previously coated with the antigen of interest. Cells producing antibody to the antigen leave an immunological fingerprint of bound antibody which is detected through the use of an ELISA technique to yield a colored plaque (Elisaplaque). Specificity of the assay was established by demonstrating that cells taken from fish vaccinated with an antigen exhibit the greatest response on plates coated with the given antigen. A strong positive correlation was also demonstrated between the number of Elisaplaques generated and serum agglutination titre. Using the ELISA plaque assay, it was found that antibody‐secreting lymphocytes located at a different density interface and behaved differently from other lymphocyte populations when separated through discontinuous Percoll gradient centrifugation. Among the haematopoietic organs examined, the head kidney appeared to produce more antibody‐secreting cells per million lymphocytes than did spleen or peripheral blood lymphocytes.
Siderophores and related outer membrane proteins in Vibrio spp. which are potential pathogens of fish and shellfish
Authors: BIOSCA E. G. , AMARO C.
Published: April 2006

Abstract. A total of eight reference strains and 43 environmental isolates of Vibrio species that are potential fish pathogens, were assayed for the production and utilization of siderophores. Chemical and biological assays indicated that all species produced phenolate compounds and only some strains of V. cholerae non‐O1, V. parahaemolyticus and V. fluvialis produced hydroxamates. Bioassays indicated that all species produced compounds that stimulated the growth of the homologous and the heterologous species in low‐iron media. The catechol‐type siderophores produced may be functionally related to enterobactin as demonstrated by bioassays with enterobactin‐deficient mutants. However, the chromatographic analysis and absorption spectra of supernatants and their extracts showed some differences among catechols excreted by Vibrio species. The hydroxamate compounds produced by some strains of V. fluvialis and V. parahaemolyticus were different from the aerobactin. The synthesis of iron‐regulated outer membrane proteins was also examined in representative strains of each species. The molecular size of the main induced proteins ranged between 74 and 95kDa, and were relatively species specific.
An appraisal of the extracellular toxins ofAeromonas salmonicidassp.salmonicida
Authors: ELLIS A. E.
Published: April 2006

Abstract.Aeromonas salmonicidaproduces many extracellular enzymes, some of which are known to play an important role in pathogenesis and virulence, while the role of others is presently speculative. The latter group includes amylase, aryl‐sulphatase, glucosidases, esterases and lysophospholipase. There are two enzymes which are known to be of prime importance in pathogenesis: a 70‐kDa protease (caseinase) and a 25‐kDa phospholipase (glycerophospholipid: cholesterol acyltransferase, GCAT). The protease causes extensive tissue liquefaction, activates the blood clotting system and is lethal for fish at 2·4 μg/g fish. It is inhibited by α2‐macroglobulin but resistant to all the other serum protease inhibitors. Its rolein vivoappears to be as a broad spectrum protease providing amino acids forin vivogrowth. The GCAT is mainly present in a high molecular weight complex with LPS. The complex is extremely haemolytic for fish (but not mammalian) erythrocytes. It is the most lethal component of the exotoxins (lethal dose 45 ng/g fish). The complex with LPS confers enhanced toxicity to the GCAT and stability to heat and proteolytic degradation.In vitro, this toxin also has high leucocytolytic and cytolytic (RTG‐2) activity. On injection into fish, it causes very little histopathology other than a marked degranulation of eosinophilic granular cells (EGCs) in the gills. Its precise mode of pathogenesis is uncertain and appears complex. The protease and the GCAT/LPS have an additive relationship in respect to lethal doses and mixtures of the two produce extensive liquefactive and haemorrhagic lesions typical of furuncles. The possible relationship of the GCAT/LPS to other less well characterized factors (cytotoxin, leucocytolysin, haemolysin, salmolysin) is discussed.