No description available.

No description available.

This thesis investigates critically constructions of, and responses to, the declining number of salmon returning annually to Scottish rivers. The focus of the research is on four related empirical topics: quantification of salmon; hatcheries and the stocking of rivers; predation of salmon by humans and animals; and Scotland's salmon management system. These topics are studied through the concepts of 'knowledge' and 'nature', following similar work in cultural geography and science studies. The research is based on a series of semi-structured interviews, guided site visits and participant observation. It also draws on responses to consultation papers, scientific research on salmon and angling literature. A reflexive approach to the research is maintained. The apparent decline of salmon stocks is often understood through quantitative calculations. During quantification, individual caught fish are transformed into numerical representations that are combined with those of other fish from around Scotland. These individual fish come to represent the Scottish national catch of salmon. Discussions of salmon stocks blur boundaries between 'scientific' and 'local' knowledges, as anglers and salmon managers freely combine national statistics with their own experimental knowledge. Three of the most significant responses to the salmon's decline are: the use of hatcheries; the imposition of management measures such as catch-and-release angling; and the control of animal predators of salmon. The thesis studies the acceptance of different animals and practices as 'appropriate' in various contexts. In discussing the stocking of rivers, perceptions of 'wildness' are key to the acceptance of hatchery-reared fish. In the conclusion, the thesis calls for a more symmetrical understanding of relationships between humans and animals, and 'scientific' and 'local' knowledges.

Settlement of Lepeophtheirus salmonis copepodids on salmonid and non-salmonid fish hosts was investigated at a variety of time points post-infection. Infection was also evaluated following previous exposure to L. salmonis to determine if cues of attached lice stimulated further settlement. A new method for estimating the surface area of a fish was devised. Consequently, surface area was examined for effect on louse burden in all fish species. The external surface of the copepodid was surveyed for potential receptors that may be used in host location and recognition. The behaviour of L. salmonis copepodids was studied on a collagen matrix containing host cues. An increase in time post-infection did not significantly affect louse burden. L. salmonis copepodids settle on fish in a hierarchy dependant on several factors including the availability of settlement sites, the species being settled and the fitness of the host. Sea trout and salmon were preferred to other hosts including rainbow trout, however all salmonid species investigated were more attractive than the non-salmonid species. In all trials, only a marginal surface area effect was seen suggesting surface area alone is not a significant factor influencing settlement. It was shown that non-host fish may be temporary reservoir hosts for the louse, but do not sustain an infection. Copepodids leave and re-attach to fish early in the settlement process, which suggests host recognition occurs early in the settlement cascade and this process involves olfaction and taste. Previously un-described mechanoreceptors have been identified at the base of the 2 nd antennae of the copepodid. Their arrangement and sensitivity also imply a significant role in host identification and settlement.

This study identified potential salmon louse gut antigens and determines the fate of salmon antibodies in the louse gut.  The characteristics and distributions of three salmon louse (<i>Lepeophtheirus salmonis</i>) gut enzymes, aminopeptidase (SLAP), alkaline phosphatase (LAlkP) and β-acetyl-hexosaminidase (LHex) are described. SLAP preferred terminal methionine residue substrates and was inhibited by leuhistin, amastatin and bestatin, identifying it as an aminopeptidase N-type enzyme. Chelators inhibited SLAP activity, and Zn²⁺ reactivated SLAP after chelation.  The enzyme was inhibited by Zn²⁺, Cu²⁺ and at 50 mM Ca²⁺, and activated by Mn²⁺ and Mg²⁺, SLAP activity was highest at pH 7.5 – 8.5. SLAP is a novel aminopeptidase as its activity was increased by molar concentrations of both NaC1 and KC1.  The enzyme is present in soluble and membrane-associated enzyme forms. LAlkP activity was highest at pH 9 – 9.5 and required bound metal cations for catalysis with both Zn²⁺ and Mg²⁺ being able to re-activate the enzyme after chelation.  LAlkP activity was also increased by molar concentrations of NaC1 and MK1.  LAlkP was predominantly present as a membrane-associated enzyme. LHex activity was greatest at pH 6.5 – 7, and inhibited by N-acetyl-galactosamine and N-acetyl-glucosamine. LHex was partially inhibited by molar concentrations of NaC1, but was relatively tolerant to high salt concentrations.  LHex was unaffected by chelation by EDTA. LHex was most able to resist denaturation by urea.  SLAP was stabilised and activated by NaC1 and TMAO.  LAlkP activity was increased by NaC1 but not by TMAO, due likely to factors not associated with stability, such as ionic forces increasing the rate of dephosphorylation. LHex was inhibited by the kosmotropic effects of both TMAO and NaC1.

The current study investigated the detrimental effects of SBM on gut integrity of rainbow trout (<i>Oncorhynchus mykiss)</i> by focusing on the response of immune-related genes and other relevant genes. Results were compared with the transcriptomic response in the intestine during<i> Aeromonas salmonicida</i> infection. During a 12 week feeding trial, a diet containing a high concentration of SBM (HSBM) caused reduced weight gain and specific growth rate. A diet containing a low concentration of SBM (LSMB) also caused reduced weight gain, although not as significant as the HSBM diet. Both the HSBM and the LSBM diet caused morphological changes in the distal intestine. SBM induced TNF-α2 gene expression in the distal intestine; COX-2 and IFN-γ expression levels were also increased at higher levels of soybean meal inclusion. Expression levels of TGF-β and IL-8 were decreased in the distal intestine. A different profile was observed in the proximal intestine. Soybean meal induced the expression of COS-2, IL-8 and IFN-γ. At higher inclusion levels of soybean meal, IL-1β expression was also increased, while TGF-β expression was decreased. Bacterial infection with <i>Aeromonas salmonicida </i>by intraperitoneal (i.p.) injection and by bath challenge induced differential cytokine expression in the head kidney and intestine. i.p. injection caused 29% mortality. Increased expression of COX-2 and decreased expression of TGF-β was observed in the distal intestine. COX-2 was also induced in the proximal intestine, while expression of TGF-β was decreased. Bath challenge caused 24% mortality. Increased expression of IL-1β, IL-8, TNF-α2, iNOS, COX2 and IFNγ was observed in the proximal intestine, as well as downregulation of TGF-β. IL-8 and COX-2 were significantly upregulated in the distal intestine and TGF-β gene expression was decreased. Differential gene expression in the intestine during infection with <i>A. salmonicida </i>by i.p. injection was investigated using SSH. Potentially upregulated immune system-related genes including MHC class I and II proteins, β-2 microglobulin type I, lysozyme II, CD83 and several lectins. Extracellular matrix-related genes included integrin, CD9, thrombospondin, fibronectin, matrix metalloproteinase, meprin A and gap junction protein β 2 were also induced, suggesting that <i>A. salmonicida</i> adheres to and invades the extracellular matrix. The transcriptomic response in the intestine of rainbow trout during SBM-induced enteritis was investigated by means of SSH and microarray. Increased expression was observed of immune system-related genes including perforin, natural killer cell enhancement factor, interleukin-1β, thioredoxin, β-thymosin and galectin, while decreased expression was observed of C-type lectin 2, eosinophil chemotactic cytokine, T-cell antigen receptor β-chain, defender against cell death 1 and iNOS.

The main focus of this investigation here involved three of the four most common salmonid <i>Gyrodactylus </i>species (<i>G. salarism G. thymalli, G. derjavini </i>and <i>G. truttae</i>), with particular attention to discriminating between <i>G. salaris </i>and <i>G. thymalli</i>.  This was accomplished by characterising uncharacterised areas of the genome, i.e. the intergenic spacer region and 28S subunit of the ribosomal array, and CO1 and ND1 gene regions of the mitochondrial genome.  Once characterisation was completed for these species, the more variable regions that would potentially be used for as a more comprehensive molecular diagnostic test, would, only then, be characterised for further chosen <i>Gyrodactylus</i> spp. The result of this investigation has now successfully documented the degree of both intra- and inter-specific variation within the IGS, 28S, ITS, 18S, CO1 and ND1 genomic regions.  As a direct result of this study’s information and techniques, the diagnostic facility at the FRS Marine Laboratory is now able to identify each strain and species of all <i>Gyrodactylus</i> species investigated to date.  In addition, the two cryptic species of <i>G. salaris</i> and <i>G. thymalli</i> can now be differentiated using three distinct ribosomal regions, namely the IGS, 5’ 28S and 3’ 28S.  This project also displays the ability to perform such characterisation on older <i>Gyrodactylus</i> species specimens, specifically those which have been preserved in ethanol for greater than 3 years, which had not been able to be utilised in the past due to the problems of DNA extraction.  The strategy of progressive and strategic characterisation (targeting smaller specific areas of the array and progressing in a certain order of profitability variation) of these specimens, sufficiently enabled the poorer quality of the DNA to be productive, and therefore beneficial in this investigation.

No description available.

No description available.

The pathogen Piscirickettsia salmonis, has been isolated from all species of salmonid and has been found in Chile, Canada, Ireland, Norway and Scotland. Rickettsia-like organisms from European sea bass (Dicentrarchus labrax) were found to share common antigens with the P. salmonis type-strain, LF-89 using the indirect fluorescent antibody test (IFAT) and immunohistochemistry (IHC). In addition, the DNA sequences of the 16S rDNA and 16S-23S internal transcribed spacer region (ITS) were compared with those published for P. salmonis strains and showed that the sea bass piscirickettsia-like organism (SBPLO) was another strain of P. salmonis, closely related to the salmonid pathogens. The ability of P. salmonis to survive and replicate within head kidney (HK) macrophages of rainbow trout infected in vitro was demonstrated using transmission electron microscopy (TEM) at various times post-infection (p.i.). However, macrophages derived from fish vaccinated against P. salmonis appeared to clear in vitro infection more rapidly than macrophages from naive fish. Polymerisation of filamentous actin within the cytoplasm of the host cell is used by some mammalian rickettsiae to achieve intercellular spread by actin-based motility (ABM). Both TEM and confocal microscopy were used to investigate possible actin tail formation by P. salmonis. No evidence of tail formation was found. Respiratory burst (RB) by P. salmonis was measured following exposure of rainbow trout HK macrophages to the organisms in vitro. Because of background stimulation of the RB by growth media and debris from the CHSE-214 cells used to culture P. salmonis, it was not possible to detect any effect of the pathogen on the burst. Schering Plough Aquaculture has developed a recombinant vaccine against P. salmonis. The ability of the vaccine to elicit a memory response against P. salmonis was investigated by measuring three different immune responses: a) the expression of iNOS was measured by reverse transcription polymerase chain reaction (RT-PCR) to detect mRNA levels or by the Greiss reaction to quantify the end-products of nitric oxide metabolism in the serum. Increased iNOS expression was not detected in rainbow trout kidney or serum following vaccination/challenge with P. salmonis. However, iNOS expression was detected in gill tissue from naive trout which suggests that expression may be constitutive in this tissue. b) the production of macrophage activating factor (MAF) by lymphocytes from vaccinated trout, following stimulation in vitro with P. salmonis, was measured by the ability of supernatants from these cells to prime elevated RB in naive macrophages. No difference in priming ability between supernatants from vaccinated and non-vaccinated fish was detected. However, macrophages among the immune leukocytes used to produce the MAF supernatants did exhibit elevated RB compared with macrophages from non-immune fish, suggesting that vaccination had produced a population of lymphocytes capable of priming activation of macrophages. c) by screening individual sera concurrently against the rickettsial and CHSE antigen preparations, the antibody response to P. salmonis could be detected specifically and was found to increase significantly in immunised fish by 6 weeks post-vaccination. Specificity of the response was demonstrated by screening the sera against Aeromonas salmonicida.