1,720,987 research outputs found
Cortisol response and immune-related effects of Atlantic salmon (Salmo salar Linnaeus) subjected to short- and long-term stress
No full textIt is generally considered that stress causes decreased immune function in fish. In this study we examined in Atlantic salmon (Salmo salar Linnaeus) the effects of both short- (a single 15 s out of water) and long-term (4 weeks of daily handling 15 s out of water) stress on plasma cortisol (free and total) and glucose levels, expression of interleukin-1\u3b2 (IL-1\u3b2) and survival of head kidney (HK) macrophages under culture with Aeromonas salmonicida. In the short-term study, samples were collected prior to the application of the stressor, and at 1, 3, 6, 12 and 24 h post stress. Free and total plasma cortisol levels and the percentage of free cortisol increased significantly in the stressed group at 1 and 3 h post stress. Plasma glucose levels were significantly higher than those of control fish at 1, 3 and 6 h post stress. Constitutive expression of IL-1\u3b2 in macrophages isolated from head kidneys in stressed fish was significantly higher at 1 and 3 h post stress. However, lipopolysaccharide (LPS) stimulated expression of IL-1\u3b2 in HK macrophages, exhibited significantly higher fold increases in unstressed fish compared to stressed fish. In the long-term study, with the exception of an increase in plasma glucose levels at 1 week, there were no significant differences in stress parameters between groups. There was a significantly higher constitutive IL-1\u3b2 expression in macrophages isolated from stressed fish over the first 2 weeks. At weeks 1, 2 and 3 the magnitude of IL-1\u3b2 response of isolated HK macrophages to LPS stimulation was reduced in >90% of the stressed fish. At 4 weeks there was no significant difference in inducible IL-1\u3b2 expression between the groups. Macrophages isolated from stressed fish also showed significantly decreased survival when exposed to A. salmonicida. This study shows a clear pattern from repeated handling stress, whereby effects on immune cells begin with increased constitutive expression of IL-1\u3b2, followed by decreased stimulation of leucocytes by extracellular antigen, and finally decreased leukocyte survival when exposed to A. salmonicida. The implications of these changes in the immune system will be discussed with respect to the use of classical indicators of stress to predict possible effects on the immune system of fish.Peer reviewed: YesNRC publication: Ye
Fish immune responses to parasitic copepod (namely sea lice) infection
No full textParasitic copepods, in particular sea lice, have considerable impacts upon global freshwater and marine fisheries, with major economic consequences recognized primarily in aquaculture. Sea lice have been a contentious issue with regards to interactions between farmed and wild populations of fish, in particular salmonids, and their potential for detrimental effects at a population level. The following discussion will pertain to aquatic parasitic copepod species for which we have significant information on the host-parasite interaction and host response to infection (Orders Cyclopoida, Poecilostomatoida and Siphonostomatoida). This review evaluates prior research in terms of contributions to understanding parasite stage specific responses by the host, and in many cases draws upon model organisms like Lepeophtheirus salmonis and Atlantic salmon to convey important concepts in fish responses to parasitic copepod infection. The article discusses TH1 and TH2-like host responses in light of parasite immunomodulation of the host, current methods of immunological stimulation and where the current and future work in this field is heading
Mutations in the Aeromonas salmonicida subsp. salmonicida type III secretion system affect Atlantic salmon leucocyte activation and downstream immune responses
No full textDeletion mutants of Aeromonas salmonicida subsp. salmonicida were used to determine the effect of the type three secretion system (TTSS) on Atlantic salmon anterior head kidney leucocytes (AHKL). One strain had a deletion in the outer membrane pore gene, ascC; and the other in three effector genes: aopO, aopH and aexT (we call this strain Δaop3). Host cell invasion success and 24h survival were depressed in ΔascC, as was 24h survival of Δaop3, when compared to the wild type strain. Challenge of AHKLs with A449 or TTSS mutants stimulated expression of the inflammatory mediators IL-8, IL-1 and TNFα at two bacterial concentrations (A600 0.1, 0.01). Expression of IL-12 was not stimulated in ΔascC challenged cells, whereas A449 and Δaop3 challenge resulted in an up-regulation of IL-12 in AHKLs, 2- and 4-fold higher than PBS, respectively. Only the wild type strain elicited a significant increase in IL-10 expression (5.5× at A600 0.1). Inducible nitric oxide synthetase (iNOS) and arginase (I+II) genes were also significantly up-regulated upon exposure to all strains. However, iNOS:arginase ratio was elevated in the effector mutant challenge. These results suggest that A. salmonicida subsp. salmonicida may enhance survival within the host cell through polarization of macrophages/leucocytes to an alternative, rather than classical, activation state. Furthermore, the short-term survival and lack of T-cell signalling cytokine stimulation in ΔascC, may help explain its inefficiency at providing protection to subsequent wild type challenge.ID: S1050464809002988; M3: Article; Accession Number: S1050464809002988; Author: Mark D. Fast (a, ∗); Author: Brenda Tse (b); Author: Jessica M. Boyd (c); Author: Stewart C. Johnson (d); Affiliation: School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794-5000, USA; Affiliation: Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada; Affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada; Affiliation: Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia, Canada; Keyword: Aeromonas salmonicida; Keyword: Type three secretion system; Keyword: Atlantic salmon; Keyword: SHK-1; Keyword: Gene expression; Keyword: Inflammation; Keyword: Activation; Keyword: Interleukin-1β; Keyword: (IL-1β); Keyword: Interleukin-10; Keyword: Interleukin-12; Number of Pages: 8; Language: English;Source type: Electronic(1
Effects of Moritella viscosa antigens on pro-inflammatory gene expression in an Atlantic salmon (Salmo salar Linnaeus) cell line (SHK-1)
No full textMoritella viscosa is the causative agent of winter ulcer disease in salmonids reared in North-Atlantic countries. In this study the effects of selected M. viscosa antigens on cytotoxicity and pro-inflammatory gene expression in an Atlantic salmon (Salmo salar Linnaeus) macrophage-like cell line (SHK-1) were examined. SHK-1 cells were stimulated with live and heat-killed bacterial cells, extracellular products (ECP) and an extracellular vibriolysin, termed MvP1. Following incubation, cytotoxicity and expression levels of interleukin-1β (IL-1β) and interleukin-8 (IL-8) were examined at different time points. Both live M. viscosa cells and ECP were cytotoxic, but neither heat-killed cells, nor the MvP1 peptidase caused cell death. Expression levels of both IL-1β and IL-8 increased significantly after stimulation with live cells, but heat-killed cells only caused increased IL-8 expression. ECP did not affect IL-1β expression, but did stimulate IL-8 expression. The isolated MvP1 peptidase stimulated both IL-1β and IL-8 expression at the highest concentration tested. This study reveals a difference in the induction of pro-inflammatory gene expression in salmon SHK-1 cells between live and heat-killed M. viscosa cells, and also that an unknown secreted factor is the main stimulant of IL-β and IL-8 expression.ID: S1050464809000990; M3: Article; Accession Number: S1050464809000990; Author: Bryndis Bjornsdottir (a, b); Author: Mark D. Fast (b, 1); Author: Sandra A. Sperker (b); Author: Laura L. Brown (b, 2); Author: Bjarnheidur K. Gudmundsdottir (a, ∗); Affiliation: Institute for Experimental Pathology, University of Iceland, Keldur v/Vesturlandsveg, 112 Reykjavík, Iceland; Affiliation: National Research Council Canada, Institute for Marine Biosciences, 1411 Oxford Street, Halifax, Nova Scotia B3H 2Z1, Canada; Keyword: Moritella viscosa; Keyword: Extracellular products; Keyword: MvP1 vibriolysin; Keyword: Atlantic salmon; Keyword: SHK-1; Keyword: Gene expression; Keyword: Immune response; Keyword: Pro-inflammatory cytokine; Keyword: Interleukin-1β (IL-1β); Keyword: Interleukin-8 (IL-8); Number of Pages: 6; Language: English;Source type: Electronic(1
Copper alters the effect of temperature on mitochondrial bioenergetics in Rainbow Trout, Oncorhynchus mykiss
No full textWe investigated the interaction of temperature and copper (Cu) on mitochondrial bioenergetics to gain insight into how temperature fluctuations imposed by natural phenomena or anthropogenic activities would modulate the effects of Cu on cellular energy homeostasis. Mitochondria were isolated from rainbow trout livers and, in the first set of experiments, exposed to Cu (0–2.5 mM) at 5, 11, and 25 °C with measurement of mitochondrial complex II (mtCII)-driven respiration. In the second set of experiments, unenergized mitochondria were incubated for 30 or 60 min with lower concentrations (0–160 μM) of Cu to measure the effects on mtCII enzyme activity. Whereas maximal (state 3) respiration was inhibited by high Cu exposure, low Cu doses stimulated and high Cu doses inhibited resting (state 4) and 4ol (proton leak) respirations. High temperature alone increased mitochondrial respiration in all states. The Q10 values for state 3, state 4, and proton leak respirations suggested active processes with state 4 respiration and proton leak exhibiting greater thermal sensitivity than state 3 respiration. The differential thermal sensitivity of resting relative to phosphorylating mitochondrial state led to uncoupling and limitation of mitochondrial oxidative capacity at both high temperature and doses of Cu. Moreover, exposure to high Cu caused loss of thermal dependence of the mitochondrial bioenergetics culminating in Q10 values well below unity and decreased activation energies (E a) for both maximal and resting respiration rates. In addition, mtCII activity was increased by low and decreased by high doses of Cu indicating that direct effects on this enzyme contribute to Cu-induced mitochondrial dysfunction. Taken together, it appears that the substrate oxidation (electron transport chain and tricarboxylic acid cycle) and proton leak subsystems are targets of the deleterious effects of Cu and increased temperature on mitochondrial bioenergetics. However, mitochondrial effects of Cu and temperature may not be easily distinguished because they are generally qualitatively similar
Dichelesthium oblongum (Copepoda: Dichelesthiidae) infestation in wild-caught Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Sea lice population and sex differences in P-glycoprotein expression and emamectin benzoate resistance on salmon farms in the Bay of Fundy, New Brunswick, Canada.
No full textParasitic sea lice are a major challenge for salmon aquaculture. This is especially due to recent development of resistance to emamectin benzoate (EMB) in the parasite. We investigated 1) whether EMB treatment success in Grand Manan, Bay of Fundy, NB, can be explained through EMB bioassay and P-gp mRNA expression studies, 2) if other populations of sea lice not under EMB selective pressure possess similar EMB sensitivity as Grand Manan sea lice populations, and 3) heritability of EMB resistance in L. salmonis.
EMB bioassay results indicated population, species, sex, and temporal differences in EMB EC50 values. RT-qPCR analyses revealed population and sex differences in P-gp mRNA levels, correlating with the bioassay results. Laboratory-reared sea lice maintained their EMB sensitivity status up to the F3 generation. Caligus elongatus, collected from Grand Manan showed >2 fold lower EMB EC50 values compared with L. salmonis collected from the same site. Concurrent exposure to EMB and verapamil yielded no increase in C. elongatus sensitivity to the parasiticide.
Sea lice bioassay and P-gp mRNA studies can be used to track EMB resistance and sex differences in EMB sensitivity and P-gp mRNA levels exist in the parasite
- …
