Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Responses to ectoparasite salmon louse (Lepeophtheirus salmonis) in spleen of Atlantic salmon

ABSTRACT: Gene expression profiling revealed rapid activation of immunity, both local and systemic, which however did not provide protection of fish against the parasite. Major changes of transcriptome responses wwere observed between days 5 and 10 Atlantic salmon was challenged with L. salmonis at the copepod stage. Skin, spleen, and head kidney were sampled from challenged and control fish at 1, 3, 5 dpi (corresponding to the copepod stage); 10 and 15 dpi (chalimus stage). A total of forty samples of spleen and skin form infected salmon (4 individuals from the 5 time points) were used for microarray analyses.. Test samples were labeled with Cy5 and hybridized to pooled control samples labeled with Cy3 from the same time-points. Competitive hybridization to the arrays was followed by washing, scanning, image analysis, and data analysis. Selected genes were analyzed with RT-qPCR.

ORGANISM(S): Salmo salar

SUBMITTER: Aleksei Krasnov

PROVIDER: E-GEOD-26984 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

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.

Tadiso Tariku Markos TM Krasnov Aleksei A Skugor Stanko S Afanasyev Sergey S Hordvik Ivar I Nilsen Frank F

BMC genomics 20110307

<h4>Background</h4>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 o ...[more]

PMID: 21385383

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Project description:Cardiomyopathy syndrome (CMS) is a disease associated with severe myocarditis in adult Atlantic salmon (Salmo salar L.), which is presumably caused with a double-stranded RNA virus (piscine myocarditis virus; PMCV). This study addressed the host immune response in Atlantic salmon during experimentally induced CMS as assessed by microarray transcriptome profiling. Post-smolts were infected by intraperitoneal injection of PMCV and developed cardiac pathology consistent with CMS. From analysis of heart samples at several time points and different tissues at early and clinical stages by oligonucleotide microarrays, six gene sets representing a broad range of immune responses were identified. Histopathological examination of cardiac tissue showed myocardial lesions from 6 weeks post infection (wpi) that peaked at 8-9 wpi and was followed by a recovery. Viral RNA was detected in all organs from 2 wpi. The highest and equal viral load was observed in heart, spleen and kidney, peaking at 8-9 wpi. Strong and systemic induction of antiviral and IFN-dependent genes from 2 wpi that leveled off during infection, was followed by a biphasic activation of pathways for B cells and MHC antigen presentation, both peaking at clinical pathology. This was preceded by a distinct cardiac activation of complement at 6 wpi. Most severe cardiac pathology and peak viraemia coincided with a cardiac-specific activation of T cell responses dominated by genes involved in effector CD8 cell responses and splenic induction of complement. These changes preceded the reduction in viral load and pathology, suggesting an important role of cytotoxic T cells for viral elimination in infected heart. Atlantic salmon post-smolts (average weight 50g) were challenged with the putative CMS-causing pathogen (PMCV). Hearts were sampled from challenged and control fish at 2, 4, 6, 8, 9 and 10 wpi. Pools of equal amounts of total RNA from three fish hearts each were combined and hybridized against control pools of 8 to 10 fish hearts per time point. Spleen, liver, mid-kidney, red blood cells (RBC) and peripheral blood leukocytes (PBL) were analyzed at 4 wpi (latest time point before clinical stage) and 8 wpi (peak pathology). The samples of infected fish were labeled with Cy5 and hybridized to control samples from the same time-points labeled with Cy3. Competitive hybridization to the arrays was followed by washing, scanning, image analysis, and data analysis. Selected genes were analyzed with RT-qPCR.

Project description:Study was performed to improve understanding of erythropoiesis (EP) induced by acute anemia in Atlantic salmon. Fish was injected with a low dose of hemolytic compound phenylhydrazine (PHZ). Treatment resulted in moderate but significant reduction of hematocrit (Hct) and increased transcription of cardiac erythropoietin (epo) at 2 days post challenge (dpc), and epo receptor (epor) in spleen from 2 to 4 dpc. Oligonucleotide microarrays were used to characterize the events of EP in the spleen. These results were compared to gene expression profiles of untreated mature red blood cells (RBC) in order to search for erythroid-specific genes. Splenic responses suggested a prevalence of protective mechanisms at the first stage, characterized by induced xenobiotic metabolism and responses to oxidative and protein stress. Erythroid-specific regulation was evident at 2 dpc and enhanced by 4 dpc, and gene expression profiles witnessed a rapid establishment of RBC phenotype although Hct levels remained low. A large group of genes showed a strong correlation to globins by expression profiles. In addition to epor this included genes of heme and iron metabolism, scavengers of free radicals and chaperones, channels and transporters, markers of erythrocytes, regulators of proliferation and cell cycle arrest and many genes with unidentified roles in RBC differentiation. Induced EP in spleen was characterized by specific features, such as upregulation of virus-responsive genes and sustained high expression of proapoptotic genes including caspases. Transcriptome changes suggested an association between EP and suppression of several developmental programs including adaptive immune responses. In conclusion, acute hemolysis and resulting anemia rapidly induced EP in the spleen of Atlantic salmon, which showed both common characteristics for all vertebrates as well as fish-specific properties. Atlantic salmon was injected with a single dose of PHZ (6 mg/kg body mass) or saline. Spleen samples for microarray analyses were collected after 2 and 4 days. Additonally, red blood cells (RBC) were compared with spleen

Dataset Information

Responses to ectoparasite salmon louse (Lepeophtheirus salmonis) in spleen of Atlantic salmon

Publications

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.

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