An Illumina approach to MHC typing of Atlantic salmon.
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ABSTRACT:
SUBMITTER: Sundaram AYM
PROVIDER: S-EPMC6970960 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BACKGROUND: Genetic variation has been shown to play a significant role in determining susceptibility to the salmon louse, Lepeophtheirus salmonis. However, the mechanisms involved in differential response to infection remain poorly understood. Recent findings in Atlantic salmon (Salmo salar) have provided evidence for a potential link between marker variation at the major histocompatibility complex (MHC) and differences in lice abundance among infected siblings, suggesting that MHC genes can modulate susceptibility to the parasite. In this study, we used quantitative trait locus (QTL) analysis to test the effect of genomic regions linked to MHC class I and II on linkage groups (LG) 15 and 6, respectively. RESULTS: Significant QTL effects were detected on both LG 6 and LG 15 in sire-based analysis but the QTL regions remained unresolved due to a lack of recombination between markers. In dam-based analysis, a significant QTL was identified on LG 6, which accounted for 12.9% of within-family variance in lice abundance. However, the QTL was located at the opposite end of DAA, with no significant overlap with the MHC class II region. Interestingly, QTL modelling also revealed evidence of sex-linked differences in lice abundance, indicating that males and females may have different susceptibility to infection. CONCLUSION: Overall, QTL analysis provided relatively weak support for a proximal effect of classical MHC regions on lice abundance, which can partly be explained by linkage to other genes controlling susceptibility to L. salmonis on the same chromosome.
| S-EPMC2680909 | biostudies-other
Project description:Pathogens are increasingly emerging in human-altered environments as a serious threat to biodiversity. In this context of rapid environmental changes, improving our knowledge on the interaction between ecology and evolution is critical. The objective of this study was to evaluate the influence of an immunocompetence gene, the major histocompatibility complex (MHC) class IIbeta, on the pathogen infection levels in wild Atlantic salmon populations, Salmo salar, and identify selective agents involved in contemporary coevolution. MHC variability and bacterial infection rate were determined throughout the summer in juvenile salmon from six rivers belonging to different genetic and ecological regions in Québec, Canada. A total of 13 different pathogens were identified in kidney by DNA sequence analysis, including a predominant myxozoa, most probably recently introduced in North America. Infection rates were the highest in southern rivers at the beginning of the summer (average 47.6+/-6.3% infected fish). One MHC allele conferred a 2.9 times greater chance of being resistant to myxozoa, while another allele increased susceptibility by 3.4 times. The decrease in frequency of the susceptibility allele but not other MHC or microsatellite alleles during summer was suggestive of a mortality event from myxozoa infection. These results supported the hypothesis of pathogen-driven selection in the wild by means of frequency-dependent selection or change in selection through time and space rather than heterozygous advantage, and underline the importance of MHC standing genetic variation for facing pathogens in a changing environment.
| S-EPMC2690505 | biostudies-literature
Project description:Induction of cellular immune responses rely on Major histocompatibility complex (MHC) molecules presenting pathogenic peptides to T cells. Peptide processing, transport, loading and editing is a constitutive process in most cell types, but is accelerated upon infection. Recently, an unexpected complexity in the number of functional genes involved in MHC class I peptide cleavage, peptide transport, peptide loading and editing was found in teleosts, originating from the second and third whole genome duplication events. Salmonids have expanded upon this with functional duplicates also from a fourth unique salmonid whole genome duplication. However, little is known about how individual gene duplicates respond in the context of stimulation. Here we set out to investigate how interferon gamma (IFNg) regulates the transcription of immune genes in Atlantic salmon with particular focus on gene duplicates and MHC pathways. We identified a range of response patterns in Atlantic salmon gene duplicates, with upregulation of all duplicates for some genes, like interferon regulatory factor 1 (IRF1) and interferon induced protein 44-like (IFI44.L), but only induction of one or a few duplicates of other genes, such as TAPBP and ERAP2. A master regulator turned out to be the IRF1 and not the enhanceosome as seen in mammals. If IRF1 also collaborates with CIITA and possibly NLRC5 in regulating IFNg induction of MHCI and MHCII expression in Atlantic salmon, as in zebrafish, remains to be established. Altogether, our results show the importance of deciphering between gene duplicates, as they often respond very differently to stimulation and may have different biological functions.
| S-EPMC7573153 | biostudies-literature
Project description:The marine phase of anadromous Atlantic salmon (Salmo salar) is the least known yet one of the most crucial with regards to population persistence. Recently, declines in many salmon populations in eastern Canada have been attributed to changes in the conditions at sea, thus reducing their survival. However, marine survival estimates are difficult to obtain given that many individuals spend multiple winters in the ocean before returning to freshwater to spawn; therefore, multiple parameters need to be estimated. We develop a model that uses an age-structured projection matrix which, coupled with yearly smolt and return abundance estimates, allows us to resample a distribution of matrices weighted by how close the resulting return estimates match the simulated returns, using a sample-importance-resampling algorithm. We test this model by simulating a simple time series of salmon abundances, and generate six different scenarios of varying salmon life histories where we simulate data for one-sea-winter (1SW)-dominated and non-1SW dominated populations, as well as scenarios where the proportion returning as 1SW is stable or highly variable. We find that our model provides reasonable estimates of marine survival for the first year at sea (S1), but highly uncertain estimates of proportion returning as 1SW (Pr) and survival in the second year at sea (S2). Our exploration of variable scenarios suggests the model is able to detect temporal trends in S1 for populations that have a considerable 1SW component in the returns; the ability of the model to detect trends in S1 diminishes as the proportion of two-sea-winter fish increases. Variability in the annual proportion of fish returning as 1SW does not seem to impact model accuracy. Our approach provides an instructive stepping-stone towards a model that can be applied to empirical abundance estimates of Atlantic salmon, and anadromous fishes in general, and therefore improve our knowledge of the marine phase of their life cycles as well as examining spatial and temporal trends in their variability.
| S-EPMC7236976 | biostudies-literature
Project description:Antigen processing and presentation by major histocompatibility complex (MHC) molecules is a cornerstone in vertebrate immunity. Like mammals, teleosts possess both classical MHC class I and multiple families of divergent MHC class I genes. However, while certain mammalian MHC class I-like molecules have proven to be integral in immune regulation against a broad array of pathogens, the biological relevance of the different MHC class I lineages in fish remains elusive. This work focuses on MHC class I L lineage genes and reveals unique regulatory patterns of six genes (Sasa-lia, Sasa-lda, Sasa-lca, Sasa-lga, Sasa-lha, and Sasa-lfa) in antimicrobial immunity of Atlantic salmon (Salmo salar L.). Using two separate in vivo challenge models with different kinetics and immune pathologies combined with in vitro stimulation using viral and bacterial TLR ligands, we show that de novo synthesis of different L lineage genes is distinctly regulated in response to various microbial stimuli. Prior to the onset of classical MHC class I gene expression, lia was rapidly and systemically induced in vivo by the single-stranded (ss) RNA virus salmonid alpha virus 3 (SAV3) but not in response to the intracellular bacterium Piscirickettsia salmonis. In contrast, lga expression was upregulated in response to both viral and bacterial stimuli. A role for distinct MHC class I L-lineage genes in anti-microbial immunity in salmon was further substantiated by a marked upregulation of lia and lga gene expression in response to type I IFNa stimulation in vitro. Comparably, lha showed no transcriptional induction in response to IFNa stimulation but was strongly induced in response to a variety of viral and bacterial TLR ligands. In sharp contrast, lda showed no response to viral or bacterial challenge. Similarly, induction of lca, which is predominantly expressed in primary and secondary lymphoid tissues, was marginal with the exception of a strong and transient upregulation in pancreas following SAV3 challenge Together, these findings suggest that certain Atlantic salmon MHC class I L lineage genes play important and divergent roles in early anti-microbial response and that their regulation, in response to different activation signals, represents a system for selectively promoting the expression of distinct non-classical MHC class I genes in response to different types of immune challenges.
| S-EPMC6797598 | biostudies-literature
Project description:Genes of the major histocompatibility complex (MHC) are a likely target of mate choice because of their role in inbreeding avoidance and potential benefits for offspring immunocompetence. Evidence for female choice for complementary MHC alleles among competing males exists both for the pre- and the postmating stages. However, it remains unclear whether the latter may involve non-random fusion of gametes depending on gametic haplotypes resulting in transmission ratio distortion or non-random sequence divergence among fused gametes. We tested whether non-random gametic fusion of MHC-II haplotypes occurs in Atlantic salmon Salmo salar. We performed in vitro fertilizations that excluded interindividual sperm competition using a split family design with large clutch sample sizes to test for a possible role of the gametic haplotype in mate choice. We sequenced two MHC-II loci in 50 embryos per clutch to assess allelic frequencies and sequence divergence. We found no evidence for transmission ratio distortion at two linked MHC-II loci, nor for non-random gamete fusion with respect to MHC-II alleles. Our findings suggest that the gametic MHC-II haplotypes play no role in gamete association in Atlantic salmon and that earlier findings of MHC-based mate choice most likely reflect choice among diploid genotypes. We discuss possible explanations for these findings and how they differ from findings in mammals.
| S-EPMC5436021 | biostudies-literature
Project description:BackgroundWe have previously sequenced more than 500 kb of the duplicated MHC class I regions in Atlantic salmon. In the IA region we identified the loci for the MHC class I gene Sasa-UBA in addition to a soluble MHC class I molecule, Sasa-ULA. A pseudolocus for Sasa-UCA was identified in the nonclassical IB region. Both regions contained genes for antigen presentation, as wells as orthologues to other genes residing in the human MHC region.ResultsThe genomic localisation of two MHC class I lineages (Z and S) has been resolved. 7 BACs were sequenced using a combination of standard Sanger and 454 sequencing. The new sequence data extended the IA region with 150 kb identifying the location of one Z-lineage locus, ZAA. The IB region was extended with 350 kb including three new Z-lineage loci, ZBA, ZCA and ZDA in addition to a UGA locus. An allelic version of the IB region contained a functional UDA locus in addition to the UCA pseudolocus. Additionally a BAC harbouring two MHC class I genes (UHA) was placed on linkage group 14, while a BAC containing the S-lineage locus SAA (previously known as UAA) was placed on LG10. Gene expression studies showed limited expression range for all class I genes with exception of UBA being dominantly expressed in gut, spleen and gills, and ZAA with high expression in blood.ConclusionHere we describe the genomic organization of MHC class I loci from the U-, Z-, and S-lineages in Atlantic salmon. Nine of the described class I genes are located in the extension of the duplicated IA and IB regions, while three class I genes are found on two separate linkage groups. The gene organization of the two regions indicates that the IB region is evolving at a different pace than the IA region. Expression profiling, polymorphic content, peptide binding properties and phylogenetic relationship show that Atlantic salmon has only one MHC class Ia gene (UBA), in addition to a multitude of nonclassical MHC class I genes from the U-, S- and Z-lineages.
| S-EPMC2846915 | biostudies-literature
Project description:Untargeted metabolomics data obtained from gut samples from adult Atlantic salmon. Sample (about 200 mg) was transferred into a 1.5 ml tube and eluted with 4x wt/vol of ultra-pure water. After homogenization with a Vortex for 1-2 min the sample was centrifuged at 16.000 g for 10 min. The supernatant was transferred into a spinX centrifuge filter, and centrifuged again (15.000 g/4 C/5 min). The filtrate was collected for LC-MS/MS analysis.
2024-04-22 | MSV000094589 | MassIVE
Project description:MicroPoly(A)Pure kits (Ambion) were used to prepare mRNA from P. salmonis-infected and control Atlantic salmon macrophages. Infected and control (24 h incubation) macrophage mRNA samples were subjected to two rounds of amplification using the MessageAmp aRNA kit (Ambion) and manufacturer's instructions. Approximately 400 ng of macrophage mRNA was used as template in the first round of amplification, yielding 8.1 ug of infected macrophage aRNA and 7.8 ug of control macrophage aRNA. Approximately 1 ug of first-round macrophage aRNA was used as template in the second round of amplification, yielding 81.2 ug of infected macrophage aRNA and 83.3 ug of control macrophage aRNA. Infected and control macrophage aRNA samples were visualized on agarose gels to check quality and quantity. Except for the amounts of aRNA and reverse transcription (RT) primer used, macrophage target labeling reactions and microarray hybridizations were identical. Macrophage target syntheses used 5 ug of second-round aRNA and 5 ug of random primers (Roche). RT primers were mixed with aRNA samples, and nuclease-free H2O (Invitrogen) was added to make 10 ul total volume. Samples were incubated at 70 degrees C 4 min, then placed on ice. RT reactions included 50 mM Tris HCl pH 8.3, 75 mM KCl, 3 mM MgCl2, 10 mM DTT, 0.5 mM each dATP, dCTP, and dGTP, 0.2 mM dTTP, 0.05 mM Cy3-dUTP or Cy5-dUTP (Amersham), 40U RNAguard ribonuclease inhibitor (Amersham), and 400U Superscript II Rnase H- reverse transcriptase (Invitrogen). RT reactions were incubated at 42 degrees C for 2.5 h, followed by addition of 0.025U RNase A (Sigma) and 1.5U RNase H (New England BioLabs) and incubation at 37 degrees C for 30 min. Labeled targets were cleaned using the Qiaquick PCR purification kit (Qiagen) and precipitated, with 300 mM sodium acetate, 1 ul of 20 ug/ul glycogen (Invitrogen), and 2.5 volumes of 100% ethanol, at -20 degrees C overnight. Each labeled target was recovered by centrifugation (14,000 rpm, 4 degrees C, 1 h), washed in 70% ethanol, air-dried, and resuspended in 60 ul of hybridization buffer: 50% deionized formamide, 5X SSC, 0.1% SDS, 5 ul of 5 ug/ul oligo dT (5'T18[Q-N]3'), 5 ul of 2 ug/ul BSA (Pierce), and 2 ul of 10 ug/ul sonicated human placental DNA (Sigma). Targets were incubated at 96 degrees C for 3 min, and then at 65 degrees C until applied to microarrays. Microarrays were prepared for hybridization by washing 2 X 5 min in 0.1% SDS, washing 5 X 1 min in MilliQ H2O, immersing 3 min in 95 degrees C MilliQ H2O, and drying by centrifugation (2000 rpm, 5 min, in 50 ml conical tube). Microarray hybridizations were run in the dark under HybriSlips hybridization covers (Grace Biolabs) in slide hybridization chambers (Corning) submerged in a 45 degrees C water bath for 16 h. Coverslips were floated off in 45 degrees C (1X SSC, 0.2% SDS), and arrays were washed 1 X 10 min in 45 degrees C (1X SSC, 0.2% SDS), 3 X 4 min in room temperature (0.1X SSC, 0.1% SDS), and 4 X 4 min in room temperature 0.1X SSC. Slides were dried by centrifugation as before. Fluorescent images of hybridized arrays were acquired immediately at 10 um resolution using ScanArray Express (PerkinElmer). The Cy3 and Cy5 cyanine fluors were excited at 543 nm and 633 nm respectively, and the same laser power (90%) and photomultiplier tube (PMT) settings were used for all slides in a study (PMT 72 Cy3, PMT 63 or 64 Cy5 for macrophage study). Fluorescent intensity data were extracted from TIF images using Imagene 5.5 software (Biodiscovery). Keywords: other
2004-02-11 | GSE1012 | GEO