Confirmation of spatial patterns and temperature effects in Bluetongue virus serotype-8 transmission in NW-Europe from the 2007 reported case data     

Gert Jan Boender  Thomas J Hagenaars  Armin RW Elbers  J?rn M Gethmann  Estelle Meroc  Helene Guis  Aline A de Koeijer 《Veterinary research》2014,45(1)

Two separate analyses were carried out to understand the epidemiology of Bluetongue virus serotype 8 (BTV-8) in 2007 in North West Europe: First, the temporal change in transmission rates was compared to the evolution of temperature during that season. Second, we evaluated the spatio-temporal dynamics of newly reported outbreaks, to estimate a spatial transmission kernel. For both analyses, the approach as used before in analysing the 2006 BTV-8 epidemic had to be adapted in order to take into account the fact that the 2007 epidemic was not a newly arising epidemic, but one advancing from whereto it had already spread in 2006. We found that within the area already affected by the 2006 outbreak, the pattern of newly infected farms in 2007 cannot be explained by between-farm transmission, but rather by local re-emergence of the virus throughout that region. This indicates that persistence through winter was ubiquitous for BTV-8. Just like in 2006, we also found that the temperature at which the infection starts to spread lies close to 15 °C. Finally, we found that the shape of the transmission kernel is in line with the one from the 2006 epidemic. In conclusion, despite the substantial differences between 2006 and 2007 in temperature patterns (2006 featured a heat wave in July, whereas 2007 was more regular) and spatial epidemic extent, both the minimum temperature required for transmission and the transmission kernel were similar to those estimated for the 2006 outbreak, indicating that they are robust properties, suitable for extrapolation to other years and similar regions.  相似文献   

Flavobacterium psychrophilum in rainbow trout, Oncorhynchus mykiss (Walbaum), hatcheries: studies on broodstock, eggs, fry and environment     

Madsen L  Møller JD  Dalsgaard I 《Journal of fish diseases》2005,28(1):39-47

The occurrence of Flavobacterium psychrophilum at four rainbow trout hatcheries was investigated to provide more knowledge about the reservoirs and transmission of this bacterium. Broodstock were sampled at stripping (including both unfertilized and fertilized eggs), and the offspring were then sampled at the eyed egg and fry stages. Water and surface samples (e.g. hatchery trays) were also sampled. Flavobacterium psychrophilum was found in ovarian fluid and milt, indicating that broodstock may serve as a reservoir and are latent carriers of the pathogen. Flavobacterium psychrophilum was not found on or inside eggs, but further egg studies will be necessary to elucidate the possibility of vertical transmission of the pathogen. Flavobacterium psychrophilum was isolated from water samples, but only from water that had been in close contact with farmed rainbow trout or eggs. Flavobacterium psychrophilum isolates were characterized and compared with well-characterized strains, using degradation of elastin, serotype and ribotype profiles. Different ribotypes of F. psychrophilum were found between hatcheries, but a common ribotype A was found at all four hatcheries. Different ribotypes were found in broodstock without clinical disease, whereas only a few ribotypes (mostly ribotype A) were found in diseased fry. The same ribotype A was found in broodstock, in water samples from hatchery trays and in fry, which suggests the possibility of transmission of F. psychrophilum between broodstock and offspring.  相似文献   

Analysis of exotoxins produced by atypical isolates of Aeromonas salmonicida,by enzymatic and serological methods     

Gudmundsdóttir BK  Hvanndal I  Björnsdóttir B  Wagner U 《Journal of fish diseases》2003,26(1):15-29

In this study, exotoxins produced by 62 Aeromonas salmonicida strains and the bacterium Haemophilus piscium were analysed. Enzymatic assays, zymograms and serological detection were used to monitor secretion by bacterial strains of the previously described exotoxins P1, GCAT and AsaP1 and also the extracellular P2 metallo-gelatinase and a serine caseinase, which is different from the P1 protease and has not yet been characterized. Based on the results, the strains were divided into five groups. One comprised the type strains for A. salmonicida ssp. masoucida, H. piscium and 36% of the atypical isolates, and another, a type strain for A. salmonicida ssp. smithia together with 14% of the atypical isolates. A second type strain of A. salmonicida ssp. smithia was grouped with 8% of the atypical isolates. The largest group contained the type strains for A. salmonicida ssp. achromogenes and 38% of the atypical isolates. The type strains for A. salmonicida ssp. salmonicida were in the last group with all the four typical strains and 4% of the atypical isolates. The combination of zymogram and serological detection used is recommended as the most reliable method for characterizing A. salmonicida strains according to their exotoxin secretion.  相似文献   

Estradiol-17β-induced calcium uptake and resorption in juvenile rainbow trout,Oncorhynchus mykiss     

Petra Persson  Kristina Sundell  Björn Th Björnsson 《Fish physiology and biochemistry》1994,13(5):379-386

Juvenile rainbow trout, Oncorhynchus mykiss, were injected with estradiol-17β (E₂) in order to study the source of extra calcium needed during vitellogenesis. E₂-treatment increased the calcium uptake from the external medium as well as calcium mobilization from muscle and scale. Judged by the increase in plasma protein-bound calcium levels, the E₂-induced increase in calcium uptake is an apparent over-mobilization of calcium, i.e., the calcium uptake of the fish is in excess of what is found bound to plasma proteins. As the calcium excretion and calcium space (calculated from free plasma calcium levels) were unaffected, the excess calcium is suggested to be incorporated into internal calcium stores. This implies that the systems regulating vitellogenesis and calcium balance are integrated on the mechanistic or endocrine level, and that E₂ causes calcium mobilization of a magnitude geared to the needs of the sexually maturing female.  相似文献   

Effects of short-term starvation on ghrelin, GH-IGF system, and IGF-binding proteins in Atlantic salmon   总被引：1，自引：0，他引：1  

Hevrøy EM  Azpeleta C  Shimizu M  Lanzén A  Kaiya H  Espe M  Olsvik PA 《Fish physiology and biochemistry》2011,37(1):217-232

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Myocardial injury in dogs with snake envenomation and its relation to systemic inflammation     

Rebecca Langhorn  Frida Persson  Bjrn blad  Amelia Goddard  Johan P. Schoeman  Jakob L. Willesen  Inge Tarnow  Mads Kjelgaard‐Hansen 《Journal of Veterinary Emergency and Critical Care》2014,24(2):174-181

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The minimum dietary requirement of vitamin C in Atlantic salmon (Salmo salar) fry using Ca ascorbate-2-monophosphate as dietary source     

Kjartan Sandnes  Ole Torrissen  Rune Waagbø 《Fish physiology and biochemistry》1992,10(4):315-319

The minimum dietary vitamin C requirement for optimal growth and normal development in Atlantic salmon (Salmo salar) fry at the onset of feeding was studied, using Ca ascorbate-2-monophosphate (AP) as dietary source. The requirement was established by means of a feeding study lasting for 23 weeks from the beginning of feeding. The practical diets used were supplemented with AP at levels of 0, 10, 20, 40, 80 and 160 mg ascorbic acid (AA) equivalents/kg. Growth, mortality, hydroxyproline content in skin and backbone, and AA in liver were recorded to evaluate the results. The results suggest that the minimum dietary requirement for optimal growth and normal development is in the range of 10–20 mg AA equivalents/kg dry diet during the period studied.  相似文献   

Feeding,growth and environmental requirements of Arctic charr: a review of aquaculture potential     

Malcolm Jobling  Even H. Jørgensen  Arne M. Arnesen  Einar Ringø 《Aquaculture International》1993,1(1):20-46

Interest in the cultivation of Arctic charr arose during the 1970s, and research into charr farming was instigated in the Nordic countries and in Canada. Most work has been conducted on fish from anadromous populations, although land-locked freshwater populations of Arctic charr have also received attention. Research has also been carried out in the British Isles and in the alpine regions of central Europe, where land-locked populations of charr. Small-scale commercial farming is now carried out in several countries of northern Europe and North America, and charr are reared for restocking purposes in a number of countries.Growth of charr is rapid during the early freshwater rearing stages, and quite good rates of growth can be achieved at low water temperatures. Growth may be submaximal if charr are reared in systems designed for other salmonids, and problems may arise when charr are held at low stocking densities. Growth and food conversion can be improved by exposing the fish to water currents, forcing them to swim at moderate speeds. Growth in seawater has been reported as being highly variable, probably as a result of the use of inappropriate rearing techniques and owing to the seasonal changes in the hypo-osmoregulatory ability of the charr.Prospects for aquaculture development and areas requiring further research effort are briefly discussed.  相似文献   

Transferrin mRNA in relation to liver iron storage in farmed Atlantic salmonSalmo salar     

Ane Marit Kvingedal  Anette Dehli  Kjell-Arne Rørvik 《Fish physiology and biochemistry》1996,15(4):317-322

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Replacement of fish meal in salmonid diets by soya meal reduces phosphorus excretion     

Asbjørn Bergheim  Harald Sveier 《Aquaculture International》1995,3(3):265-268

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