Transcriptome comparisons of wild, domesticated and hybrid Atlantic salmon fry under stress and control conditions
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ABSTRACT: This study compares the transcriptomes of wild and domesticated Atlantic salmon strains and their transcriptional response to acute stress. Microarray interrogations consisted of 48 hybridizations; 4 crosses (pure wild; Figgjo x Figgjo, pure domesticated; Mowi x Mowi and their reciprocal hybrids; Figgjo x Mowi, Mowi x Figgjo) x 2 conditions (stress and control) x 6 biological replicates and employed a custom 44k oligonucleotide microarray design.
Project description:Atlantic salmon (Salmo salar) has been selectively bred in Europe since the 1970s and the process of domestication has led to both phenotypic and genotypic differences between wild and farmed fish. Despite strict regulations large numbers of fish escape annually from fish farms, a concern for both aquaculturalists and those managing wild fish stocks. A better understanding of the interactions between domesticated and wild salmon is essential to the continued sustainability of the aquaculture industry and to the maintenance of healthy wild stocks. One major concern is that of potential interbreeding of escapees with wild fish leading to potentially detrimental genetic changes in wild populations. Advances in high throughput technologies allow the role of genome-wide gene transcription to be studied in relation to both micro- and macro- evolutionary change. In this study, we have compared the transcriptomes of Norwegian wild and domesticated stocks at two life stages: yolk sac and first-feeding salmon fry and reared under identical conditions. These preliminary data improve knowledge of potential transcriptional difference between domesticated and wild salmon and will hopefully provide a better understanding of the fitness consequences of such interactions.
Project description:Infectious Pancreatic Necrosis (IPN) is a highly contagious birnavirus disease of farmed salmonid fish, which often causes high levels of morbidity and mortality. A large genetic component underlying resistance to this disease has been previously described for Atlantic salmon (Salmo salar L.), which mediates high mortality rates in some families and zero mortality in others. A global comparison of the gene expression profiles of resistant and susceptible Atlantic salmon fry following challenge with the IPN virus was undertaken. Full sibling salmon fry from two IPNV-resistant and two IPNV-susceptible families were challenged with the virus and sampled at 1 day, 7 days and 20 days post-challenge. Significant viral titre was observed in both resistant and susceptible fish at all timepoints, although generally at higher levels in susceptible fish. Microarray interrogations were performed using a custom-designed, oligonucleotide microarray platform (Agilent) with 44 K probes per slide (Salar_2; Agilent Design ID:025520). The design is lodged with ArrayExpress ( under accession number A-MEXP-2065. Dual-label hybridisations were undertaken, with each experimental sample (Cy3 labelled) being competitively hybridised against a pooled reference control (Cy5 labelled) comprising equimolar amounts from each experimental RNA sample. The interrogations comprised 144 separate hybridisations; 2 genotypes (susceptible, resistant) à 2 families for each genotype à 2 challenge states (control, challenged) à 3 timepoints (1, 7, 20 dpi) à 4 biological replicates for resistant (2 from each of two tanks) and 8 biological replicates for susceptible (4 from each of two tanks). A preliminary analysis suggested evidence for a segregating QTL in both the susceptible families and therefore twice as many offspring were screened. It was later established that the evidence for QTL segregation in one of the families was inconclusive and therefore comparisons were made at the family level only. The analyses took the unbalanced design into account.
Project description:This study compares the transcriptomes of wild (Figgjo) and domesticated (Mowi) Atlantic salmon embryos, employing a custom 44k oligonucleotide microarray to identify gene pathways perturbed between wild and domesticated strains and with the aid of heir reciprocal hybrids, to examine the heritability of differentially expressed genes.
Project description:Infectious pancreatic necrosis (IPN) is widespread disease with global distribution and highly contagious, which leads to severe economic problems both freshwater and saltwater, particularly in the Atlantic salmon (Salmo salar). In this work we analyzed and evaluated gene expression profiles in resistant and susceptible families associated to S. salar exposed to IPNV in order to understand the defense mechanisms mounted by resistant fish in combating infection. Experimentally, 29 families with known pedigree and variability were infected by immersion with 1x106 PFU/ml of IPNV, and a gamma frailty model analysis based on Kaplan-Meier mortality curves were obtained to identify and classify families as susceptible or resistant. Samples of head kidney tissue were obtained at day 1 and 5 post-infection from susceptible and resistant families and pooled to analyse their expression pattern with realt-ime PCR and one-color salmon-specific oligonucleotide microarray (21K). The microarray results showed clear differences in both families, where resistant fish presented an over-expression of genes associated with endocrine function, and a down-regulation of genes associated principally with tissue differentiation, metabolism protein degradation, cell signaling and immunological process. Moreover qPCR analysis using as target a number of transcripts associated with immunological processes showed the same trend observing a higher expression in susceptible than resistant families, indicating significant differences for CCL-19, CCRM-NM-3c, IL-12, IFN-M-NM-1, and IFN-M-NM-3. The one-color oligonucleotide microarrays included in this study was performed using pooled samples from each families at two different post-infection time condition. In the case of susceptible families were chosen at 1 day post-infection (dpi) the families 5352 (n = 2) and 5469 (n = 2) and at 5 dpi the families 5629 (n = 2) and 5637 (n = 2), whereas in resistant families were selected at 1 dpi the families 5459 (n =3) and 5761 (n =3), and at 5 dpi the families 5463 (n =3) and 5764 (n =3).
Project description:Liver transcriptomes of Atlantic salmon families with contrasting flesh n-3 LC-PUFA profiles, and all fed the same 100% vegetable oil replacement diet, were compared by microarray analysis (Agilent oligoarray platform). The objective was to identify gene pathways and molecular mechanisms which might explain differences in flesh n-3 LC-PUFA content, independent of total lipid deposition, when salmon families are fed the same LC-PUFA deficient diet. A factorial design was chosen in which families containing higher and lower n-3 LC-PUFA relative levels were compared at similar total lipid percentages in flesh.
Project description:Background: The decreasing availability of fishmeal as a protein source in aquaculture diets will require aquaculture to develop an econmoical and sustainable protien replacement. Plant proteins are readily available and are being tested as a promising alternative to replace a substantial portion of fishmeal which currently provides most of the protein content in aquaculture diets. The types of plant protein feasible for incorporation into aquaculture diets will likely contain various anti-nutritional compounds, carbohydrates, fiber, and a different amino acid profile than what is found in fishmeal. Substantial genetic variation was previously observed for growth on plant based dits in rainbow trout Hence, it will be beneficial to identify metabolic and physiologic pathways related to enhanced plant protein utilization which will aid in identifying genes that contribute to this genetic variation. Results: Microarray analysis of liver samples from two families of rainbow trout that differed in their growth responses when compared between individuals grown on a fish meal or plant protein based diet. Differential expression relating to dietary utilization between the two families found significant changes in expression of 33 ESTs. Eight of the differntially expressed ESTs had identified mammalian homologs that had been previously researched with identified cellular interactions and functions. Conclusions: Utilizing pathway analysis software to analyze sequences annotated with known mammalian genes were were ablet o map gene pathway and process interactions. From this information we were able to infer that the metabolic changes associated with utilization of plant protein versus fishmeal were associated with differential reaulation of genes related to cell oxidative stress, proliferation, growth, and survival. Furthermore, we inferred from the changes we observed in immune response genes expression that ingestion of this plant based diet upregulated the expression of genes involved in immunoregulatroy processes. Genotyped samples linked to families that had 4 or more members sampled on each diet were identified and ranked according to average family weight on each diet. Size rankings corresponded to large (>750 g), medium (600-640 g), and small (<500 g). From these identified groups 2 families were chosen for microarray expression analysis that demonstrated individuals with growth differences between the two diets. Data for the two families used for analysis and slide arrangements are listed in table 3. The families compared for growth differences between diets used for this study only differed by one growth range, large fish on fish meal compared to medium fish on plant-based diet and medium sized fish on fishmeal diet compared to small fish on plant-based diet. This strategy to use size separation within family was an attempt to identify gene changes more specific to diet utilization than specific for growth differences.
Project description:The anadromous Atlantic salmon undergo preparatory physiological transformations before seawater entry, referred to as smoltification. Little is known about the photoperiod-influence and genome regulatory processes driving smoltification such as the large scale changes in lipid metabolism and energy homeostasis in the developing smolt liver. To shed light on this, we performed a smoltification trial using contrasting photoperiod regimes and generate ATAC-seq data from livers throughout smoltification and after seawater transfer to assess the differences in chromatin accessibility. In this experiment Atlantic salmon were reared for a total of 46 weeks from the parr stage, through smoltification, and seawater transfer. After 21 week from first feeding, the group was given artificial winter photoperiod (8 hours light, 16 hours dark) for 8 weeks to induce smoltification before returning to constant light. Liver tissue was sampled from individuals first at week 1, 21 weeks after first feeding, then again at week 10, after the winter period, at week 19, after the expected smoltification time, and lastly at week 25, after transfer to seawater.
Project description:Total RNA was extracted from liver tissues of lab-reared threespine stickleback. First generation fish originating from the Baltic Sea near Helsinki (Finland) were bred using a paternal half-sib design. At 6 months individuals were randomly assigned to either a treatment or control group: the temperature of treated fish (T) was raised 1oC per hour over the course of 6h to a final temperature of 23oC, then maintained for 1h at final temperature; control (C) fish were maintained at 17oC under similar holding conditions. Immediately following experimental (or sham) treatment, fish were euthanized by anaesthetic overdose. Liver tissues were immediately dissected and flash frozen in liquid nitrogen for subsequent RNA extraction. Annotated R scripts defining the normalization procedures are available as additional files (see http://www.ebi.ac.uk/arrayexpress/files/E-MTAB-3098). Additional files also include a targets file to assist with reading raw data into R (Targs.txt), and a metadata file (matrix.df.csv) to facilitate construction of design matrices used by the M-bsnmM-b package.
Project description:Total RNA was extracted from liver tissues of lab-reared threespine stickleback. The dataset combines transcripts common to two experiments: first generation fish originating from the Baltic Sea near Helsinki (Finland) bred using a paternal half-sib design (E-MTAB-3098), and second generation fish originating from three different Fennoscandian populations bred from a full-sib design. Annotated R scripts defining the normalization procedures are available as additional files (see http://www.ebi.ac.uk/arrayexpress/files/E-MTAB-3099). Additional files also include a metadata file (matrix.df.csv) to facilitate construction of design matrices used by the snm package.
Project description:The anadromous Atlantic salmon undergo preparatory physiological transformations before seawater entry, referred to as smoltification. Little is known about the photoperiod-influence and genome regulatory processes driving smoltification such as the large scale changes in lipid metabolism and energy homeostasis in the developing smolt liver. To shed light on this, we performed a smoltification trial using contrasting photoperiod regimes and generate a transcriptome data from livers throughout smoltification and after seawater transfer. In this experiment two groups of Atlantic salmon were reared for a total of 46 weeks from the parr stage, through smoltification, and seawater transfer. After 21 week from first feeding, the experiment group was given artificial winter photoperiod (8 hours light, 16 hours dark) for 8 weeks to induce smoltification before returning to constant light. The second control group received constant light throughout the experiment. Liver tissue was sampled from individuals first at week 1, 21 weeks after first feeding, then again at week 10, after the winter period, at week 19, after the expected smoltification time, and lastly at week 25, after transfer to seawater.