Gene expression analyses of immune responses in Atlantic salmon during early stages of infection by salmon louse (Lepeophtheirus salmonis) revealed bi-phasic responses coinciding with the copepod-chalimus transition.
BACKGROUND: The salmon louse (Lepeophtheirus salmonis Krøyer), an ectoparasitic copepod with a complex life cycle causes significant losses in salmon aquaculture. Pesticide treatments against the parasite raise environmental concerns and their efficacy is gradually decreasing. Improvement of fish resistance to lice, through biological control methods, needs better understanding of the protective mechanisms. We used a 21 k oligonucleotide microarray and RT-qPCR to examine the time-course of immun ...[more]
Project description:This SuperSeries is composed of the following subset Series: GSE26981: Responses to ectoparasite salmon louse (Lepeophtheirus salmonis) in skin of Atlantic salmon GSE26984: Responses to ectoparasite salmon louse (Lepeophtheirus salmonis) in spleen of Atlantic salmon Refer to individual Series
Project description:This study investigates host-specific gene expression of the Pacific salmon lice, Lepeophtheirus salmonis oncorhynchii, while parasitizing a resistant host (Coho salmon), two susceptible hosts (Atlantic salmon, Sockeye salmon), and a population with-held hosts (starved), over 48 hrs. Overall design: Adult female sea lice were allowed to attach to three different host populations (Atlantic, Coho and Sockeye salmon), or were kept in incubation chambers devoid of hosts (starved). At 0, 24, and 48 hours, individual lice were sampled for subsequent RNA analysis.
Project description:This study investigates the transcriptomic responses of salmon lice (L. salmonis) infecting salmon treated with emamectin benzoate (either 1x or 3x), ivermectin, or commercial feed controls Overall design: Copepodid-staged larvae of L. salmonis were used to infect Atlantic salmon fed 1x or 3x emamectin benzoate, ivermectin, or commercial feed controls. Pre-adult I lice were collected from each group, pooled by treatment group and sex (pools of 6 lice) and stored at -80C for RNA extraction and microarray analyses. A total of 48 pools were used (n = 6 per condition except n = 5 for male controls and n = 7 for male 3xEMB)
Project description:We investigate the effect of a functional feed for immunostimulation (peptidoglycan extract from bacterial cell wall with nucleotide formulation) on L. salmonis infection levels on Atlantic salmon Salmo salar, and on host and parasite gene expression profiles. Atlantic salmon smolts (~95 g) were fed a control diet, or a low or high dose immunostimulant diet, and then exposed to L. salmonis copepodids in three subsequent exposures. The transcriptome of salmon lice late in the infection attached to either the low dose diet or control diet hosts were compared using a 38K oligonucleotide microarray. Overall design: Atlantic L. salmonis copepods were used to infect Atlantic salmon on an immunostimulant diet, and upon development to the adult stage the lice were collected and profiled. Lice are either feeding on immunostimulant-fed or control-fed salmon. Lice samples are equal numbers of males and females.
Project description:Glucosinolates (GLs) present in plants from the Brassica family hold promise in the biological control of the skin parasite salmon louse (Lepeophtheirus salmonis) in farmed Atlantic salmon. We recently reported significantly reduced lice infestation in fish fed GLs. However, their wider application requires better knowledge of GLs’ actions, including positive and adverse effects that may occur under the overexposure. Microarray analyses performed in the liver, muscle and distal kidney of salmon under high dose of GLs suggested massive tissue remodeling and reduction of cellular proliferation in skeletal muscle and liver. In the distal kidney, gene expression profiles induced under the high dose of GLs pointed to activation of anti-fibrotic responses. At the same time, prevalent activation of genes from the Phase-2 detoxification pathways could be considered part of beneficial effects. Multiple gene expression evidence suggested GLs-mediated iron/heme withdrawal response, including increase in heme degradation in muscle (up-regulation of heme oxygenase-1), decrease of its synthesis in liver (down-regulation of porphobilinogen deaminase) and increase in iron sequestration from blood (hepatic induction of hepcidin-1 and renal induction of intracellular storage protein ferritin). This could be beneficial upon encounter with the parasite, which depends on the provision of iron/heme by the host. Overall design: Atlantic salmon received control feed and feed with 13% of the GL-containing raw ingredient during three weeks. Microarray analyses were performed in distal kidney, liver and muscle.
Project description:Salmon infected with an ectoparasitic marine copepod, the salmon louse Lepeophtheirus salmonis, incur a wide variety of consequences depending upon host sensitivity. Juvenile pink salmon (Oncorhynchus gorbuscha) migrate from natal freshwater systems to the ocean at a young age relative to other Pacific salmon, and require rapid development of appropriate defences against marine pathogens. We analyzed the early transcriptomic responses of naïve juvenile pink salmon of sizes 0.3g (no scales), 0.7g (mid-scale development) and 2.4g (scales fully developed) to a low-level laboratory exposure with early moult stage L. salmonis. All infected size groups exhibited unique transcriptional profiles. Inflammation and inhibition of cell proliferation was identified in the smallest size class (0.3g), while increased glucose absorption and retention was identified in the middle size class (0.7g). Tissue-remodelling genes were also up-regulated in both the 0.3g and 0.7g size groups. Profiles of the 2.4g size class indicated cell-mediated immunity and possibly parasite-induced growth augmentation. Understanding a size-based threshold of resistance to L. salmonis is important for fisheries management. This work characterizes molecular responses reflecting the gradual development of innate immunity to L. salmonis between the susceptible (0.3g) and refractory (2.4g) pink salmon size classes. Overall design: Six-condition experiment, 3 size groups each infected and uninfected, duplicate tanks. Biological replicates: 6 control, 6 infected for each size group. Sampled 6 days post exposure. cDNA samples with reference design (aRNA), two-color array.