Transcription profiling of Gadus morhua pituitary gland, pylorus, spleen and testis to validate the IMR Atlantic Cod 16k cDNA array
ABSTRACT: The Atlantic cod, Gadus morhua, is an important species both for traditional fishery and increasingly also in fish farming. The Atlantic cod is also under potential threat from various environmental changes such as pollution and climate change, but the biological impact of such changes are not well known, in particular when it comes to sublethal effects that can be difficult to assert. Modern molecular and genomic approaches have revolutionized biological research during the last decade, and offer new avenues to study biological functions and e.g. the impact of anthropogenic activities at different life-stages for a given organism. In order to develop genomic data and genomic tools for Atlantic cod we conducted a program were we constructed 20 cDNA libraries, and produced and analyzed 44006 expressed sequence tags (ESTs) from these. Several tissues are represented in the multiple cDNA libraries, that differ in either sexual maturation or immulogical stimulation. This approach allowed us to identify genes that are expressed in particular tissues, life-stages or in response to specific stimuli, and also gives us information about potential functions of the transcripts. The ESTs were used to construct a 16 k cDNA microarray to further investigate the cod transcriptome. Microarray analyses were preformed on pylorus, pituitary gland, spleen and testis of sexually maturing male cod. The four different tissues displayed tissue specific transcriptomes demonstrating that the cDNA array is working as expected and will prove to be a powerful tool in further experiments.
Project description:In the present study we aimed to develop a custom made cDNA microarray, the CodStress array, for Atlantic cod to be used as a diagnostic tool in environmental monitoring of polluted waters. We wanted to investigate if the gene expression profiles would reflect environmental levels and composition of pollutants in two saltwater recipients, S?rfjorden and Store Lungeg?rdsvann.
Project description:This study was performed to validate the newly developed CGP Atlantic cod 20K oligonucleotide microarray. Atlantic cod (Gadus morhua) received an intraperitoneal injection of either formalin-killed, atypical Aeromonas salmonicida (Asal) or PBS and transcriptional profiles of spleen tissues from Asal-injected fish were compared to those from pre-injection control fish and PBS-injected control fish. Gene expression profiles resulting from this study were compared to those from suppression subtractive hybridization library studies, that were previously performed on the same samples, and to literature. Gene expression patterns of single genes were confirmed by QPCR analysis. This study has shown that the newly developed CGP Atlantic cod 20K oligo microarray platform is a valuable tool for cod genomic research. Fish were assigned to 1 of 3 groups: Asal group, PBS group or 'undisturbed control' group (the latter were not handled during the experiment). These groups were kept in 3 separate tanks. For the test samples, RNA was used from individual spleen samples that were taken from 6 fish from each of 4 treatment groups: PBS group pre-injection (0H PBS), Asal group pre-injection (0H Asal), PBS group 24 hours post-injection (24HPI PBS) and Asal group 24 hours post-injection (24HPI Asal). All test samples were labeled with AlexaFluor 647. For the universal reference sample, RNA from 31 'undisturbed control' fish was pooled, with each individual contributing an equal amount, and labeled with AlexaFluor 555. Each individual test sample was hybridized together with the universal reference sample on an array. For one sample from the 0H PBS group the array failed. This study therefore includes 6 biological replicates for 0H Asal, 24HPI Asal and 24HPI PBS groups and 5 biological replicates for the 0H PBS group.
Project description:Transcripts of the gill epithelium from three different stocks of Atlantic salmon (Salmo salar) migrating from freshwater river to lake (Saimaa stock, SS), brackish water (Neva stock, NS) or seawater (Teno stock, TS) were compared at three successive developmental stages (parr, smolt and postsmolt) using the 16K GRASP cDNA microarray platform.
Project description:Concerns have arisen recently over the possible environmental effects of human pharmaceuticals. Although acute toxicities are low, the continuous discharge of pharmaceuticals into the aquatic environment, coupled with the fact that such compounds are selected for use on the basis of a strong pharmacological effect, means that sublethal effects on non-target organisms need to be seriously considered. The juvenile stages of Atlantic salmon are present in many northern European rivers which are also used for the discharge of domestic wastewaters likely to contain pharmaceuticals. One year old salmon parr were exposed to an environmentally relevant concentration (5µg·/ L) of the antidepressant drug carbamazepine for five days and changes of mRNA expression in brain tissues were investigated by means of a custom 17k Atlantic salmon cDNA microarray. The TRAITS 17K Atlantic salmon cDNA microarray was employed. A dual-labelled experimental design was employed for the microarray hybridisations. Each experimental cDNA sample (Cy3 labeled) was competitively hybridised against a common pooled-reference sample (Cy5 labeled). The entire experiment comprised 10 hybridisations - 2 states (CBZ exposed / unexposed) × 1 time-point ( at 5 days) × 5 biological replicates (males only). Hybridisations were undertaken concurrently.
Project description:Understanding pathogen recognition and mechanisms in Atlantic cod are of significant importance for both basic research on wild populations and health management in aquaculture. A microarray approach was utilized to search for effects of viral (poly I:C/ polyinosinic acid:polycytidylic acid), bacterial (LPS/lipopolysaccharide) and polyclonal activator (PHA-L/phytohaemoagglutinin) stress in Atlantic cod head kidney cells. LPS cell activation increased mRNA expression of chemokine/Interleukin 8 (CXCL8/IL-8); interleukin -1? (IL-1?); cyclooxygenase 2 (COX2); leukocyte derived chemotaxin 2 (LECT2); LOC100698154, encoding a protein with unknown function; carboxyl-esterase 2 (CES2) and environmental biomarker cytochrome P450 1A (CYP1A). Mitogen activated protein kinase p38 (p38MAPK) and cathepsin F (CTSF) were downregulated by LPS. The antiviral responses induced by double stranded RNA (Poly I:C) clearly increased transcription of Toll like receptor 3 (TLR3) and interferon stimulating gene 15 (ISG15). The PHA response seemed to be more non-specific. Special for the PHA induction were the increase in Major histocompatibility complex class I (MHCI). CC chemokine type 2 (CK2) mRNA expression was increased by PHA, LPS and poly I:C, while p38MAPK and LECT2 was downregulated by PHA. Oxidative stress related genes like catalase and glutaredoxin (GLRX2) and the anti-apoptotic gene Bcl-2 showed no transcriptional changes compared to control in any of the treatments. Especially Poly I:C, but also LPS, induced leukotriene B4 (LTB4) and leukotriene B5 (LTB5) synthesis, while small amounts of prostaglandine E2 (PGE2) seemed to be constitutively produced in untreated cells, a production that was slightly elevated when exposing cells for LPS. This study reveals distinct signatures of bacteria and virus transcriptional responses in cod head kidney cells. In addition, the novel finding that Cyp1a was upregulated during the antibacterial response indicates a connection between immunity and aryl hydrocarbon receptor (AhR) activation in Atlantic cod.
Project description:This experiment was conducted in order to evaluate the potential contribution of oil droplets to the toxicity of dispersed oil to fish larvae. Atlantic cod larvae were exposed to five concentrations of either dispersed oil (D1-D5) (containing oil droplets [medium size 10-14 µm based on volume] and water soluble fraction [WSF]) or the filtered dispersion containing only WSF of oil (W1-W5) for four days and harvested for transcriptional analysis at 13 days post hatching. The most significant differently expressed genes were observed in cod larvae exposed to the highest concentration of the dispersed oil (containing 10.41 ± 0.46 µg ∑PAH/L), with CYP1A showing the strongest response. Functional analysis further showed that the top scored network as analyzed with Ingenuity Pathway Analysis was “Drug Metabolism, Endocrine System Development and Function, Lipid Metabolism”. Oil exposure also increased the expression of genes involved in bone resorption and decreased the expression of genes related to bone formation. In conclusion, oil exposure affects drug metabolism, endocrine regulation, cell differentiation and proliferation, apoptosis, fatty acid biosynthesis and tissue development in Atlantic cod larvae. The altered gene transcription was dominated by the WSF and the oil droplet fraction only had a moderate impact on the observed changes.
Project description:In order to investigate the underlying mechanisms of PCB 153 mediated toxicity to Atlantic cod (Gadus morhua), we analyzed the liver proteome of fish exposed to various doses of PCB 153 (0, 0.5, 2 and 8mg/kg body weight) for two weeks and examined the effects on expression of liver proteins using quantitative proteomics. Label-free mass spectrometry enabled quantification of 1272 proteins, and 78 were differentially regulated between PCB 153 treated samples and controls. Two proteins downregulated due to PCB 153 treatment, Glutathione S-transferase theta 1 (GSTT1) and sulfotransferase family protein 1 (ST2B1), were verified using selected reaction monitoring (SRM). Supported by bioinformatics analyses, we concluded that PCB 153 perturbs lipid metabolism in the Atlantic cod liver and that increased levels of lipogenic enzymes indicate increased synthesis of fatty acids and triglycerides.
Project description:In order to investigate the underlying mechanisms of methylmecury (MeHg)-mediated toxicity to Atlantic cod (Gadus morhua), we analyzed the liver proteome of fish exposed in vivo to MeHg (0, 0.5, 2 mg/kg body weight) for 2 weeks. Label-free quantitative mass spectrometry enabled quantification of 1143 proteins, and 125 were differentially regulated between MeHg-treated samples and controls. Six proteins among the top differentially regulated (T23O, GLNA EPS8L2, APOA4, RAP1B, CZTZ) were analyzed using selected reaction monitoring (SRM). Supported by bioinformatics analyses, we conclude that MeHg disrupts mainly redox homeostasis and energy generating metabolic pathways in cod liver, the latter potentially modulated through MeHg-induced oxidative stress.