Influence of developmental stage and genotype on liver mRNA levels among wild, domesticated, and hybrid rainbow trout (Oncorhynchus mykiss)
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ABSTRACT: A 44K salmonid oligoarray was used to examine the influence of genotype and developmental stage on mRNA expression in wild-type (age matched and size matched to domesticated), domesticated and wild-domesticated hybrid populations. Significant differences were found in mRNA expression between genotypes. The largest proportion of differentially expressed mRNAs were found in comparisons of domesticated and wild-type groups. Significant differences were also noted in pairings of wild-domesticated hybrid progeny to both parental strains. Differences in gene expression were found in comparison of both wild-type age and size matched to each other and in combination with genotype analysis, showing a strong effect of fish developmental stage on differential gene expression. Domestication was found to modify biological pathways associated with transport, metabolism, cell tissue structure and development, stress and immune response and protein synthesis. Genotype analysis of hybrid progeny inheritance patterns showed similar levels of recessive, dominant and additive effects.
Project description:A 44K salmonid oligoarray was used to examine the influence of genotype and developmental stage on mRNA expression in wild-type (age matched and size matched to domesticated), domesticated and wild-domesticated hybrid populations. Significant differences were found in mRNA expression between genotypes. The largest proportion of differentially expressed mRNAs were found in comparisons of domesticated and wild-type groups. Significant differences were also noted in pairings of wild-domesticated hybrid progeny to both parental strains. Differences in gene expression were found in comparison of both wild-type age and size matched to each other and in combination with genotype analysis, showing a strong effect of fish developmental stage on differential gene expression. Domestication was found to modify biological pathways associated with transport, metabolism, cell tissue structure and development, stress and immune response and protein synthesis. Genotype analysis of hybrid progeny inheritance patterns showed similar levels of recessive, dominant and additive effects. Microarray analysis was performed on liver RNA from 6 individual fish per group of age-matched wild, size-matched wild, domesticated and wild-domesticated hybrids. Samples were hybridized against a common wild-type reference pool (n=6 wild size-matched fish). One individual from each of the groups was hybridized to one array on each of the individual slides (n=6) in the order of domestic, hybrid, age-matched wild and size-matched wild. In total, 6 4x44K oligoarray slides were used to complete the study.
Project description:Growth rate can be genetically modified in many vertebrates by domestication and selection, and more recently by transgenesis overexpressing growth factor genes (e.g. growth hormone, GH). While the phenotypic end consequence is similar, it is currently not clear whether the same modifications to physiological pathways are occurring in both genetic processes, nor to what extent they may interact when combined. To examine these questions, we have used rainbow trout as a model species because non-domesticated wild strains are available as comparators to assess genetic and physiological changes that have arisen from domestication and from GH transgenesis. In addition to pure wild and pure domesticated strains, two different GH transgenes with markedly different growth effects were examined, both in a wild background and in hybrids which combined domesticated and wild genomes in addition to the transgene. We find that liver mRNAs show highly concordant changes in levels in both types of fast-growing fish, relative to wild type, for both up- and down-regulated genes. Further, among domesticated, transgenic, and their hybrid genotypes, a strong positive correlation was found between growth rate and the number of genes affected or their levels of mRNA. Functional analysis found that genes involved in immune function, carbohydrate metabolism, detoxification, transcription regulation, growth regulation, and lipid metabolism were affected in common by domestication and GH transgenesis. The common responses of domesticated and GH transgenic strains is consistent with the GH pathway or its downstream effects being upregulated in domesticated animals during their modification from wild-type growth rates. Microarray analyses were performed on five individual rainbow trout per group of pure wild, pure domesticated, GH transgenic strain 1 in wild, GH transgenic strain 2 in wild, GH transgenic strain 1 in wild-domestic hybrid, and GH transgenic strain 2 in wild-domestic hybrid hybridized (one slide per individual) against a common wild-type RNA pool.
Project description:Growth rate can be genetically modified in many vertebrates by domestication and selection, and more recently by transgenesis overexpressing growth factor genes (e.g. growth hormone, GH). While the phenotypic end consequence is similar, it is currently not clear whether the same modifications to physiological pathways are occurring in both genetic processes, nor to what extent they may interact when combined. To examine these questions, we have used rainbow trout as a model species because non-domesticated wild strains are available as comparators to assess genetic and physiological changes that have arisen from domestication and from GH transgenesis. In addition to pure wild and pure domesticated strains, two different GH transgenes with markedly different growth effects were examined, both in a wild background and in hybrids which combined domesticated and wild genomes in addition to the transgene. We find that liver mRNAs show highly concordant changes in levels in both types of fast-growing fish, relative to wild type, for both up- and down-regulated genes. Further, among domesticated, transgenic, and their hybrid genotypes, a strong positive correlation was found between growth rate and the number of genes affected or their levels of mRNA. Functional analysis found that genes involved in immune function, carbohydrate metabolism, detoxification, transcription regulation, growth regulation, and lipid metabolism were affected in common by domestication and GH transgenesis. The common responses of domesticated and GH transgenic strains is consistent with the GH pathway or its downstream effects being upregulated in domesticated animals during their modification from wild-type growth rates.
Project description:Escaped domesticated individuals can introduce disadvantageous traits into wild populations due to both adaptive differences between population ancestors and human-induced changes during domestication. In contrast to their domesticated counterparts, some endangered wild Atlantic salmon populations encounter during their marine stage large amounts of suspended sediments, which may act as a selective agent. We used microarrays to elucidate quantitative transcriptional differences between a domesticated salmon strain, a wild population and their first-generation hybrids during their marine life stage, to describe transcriptional responses to natural suspended sediments, and to test for adaptive genetic variation in plasticity relating to a history of natural exposure or nonexposure to suspended sediments. We identified 67 genes differing in transcription level among salmon groups. Among these genes, processes related to energy metabolism and ion homoeostasis were over-represented, while genes contributing to immunity and actin-/myosin-related processes were also involved in strain differentiation. Domestic–wild hybrids exhibited intermediate transcription patterns relative to their parents for two-thirds of all genes that differed between their parents; however, genes deviating from additivity tended to have similar levels to those expressed by the wild parent. Sediments induced increases in transcription levels of eight genes, some of which are known to contribute to external or intracellular damage mitigation. Although genetic variation in plasticity did not differ significantly between groups after correcting for multiple comparisons, two genes (metallothionein and glutathione reductase) tended to be more plastic in response to suspended sediments in wild and hybrid salmon, and merit further examination as candidate genes under natural selection.
Project description:Escaped domesticated individuals can introduce disadvantageous traits into wild populations due to both adaptive differences between population ancestors and human-induced changes during domestication. In contrast to their domesticated counterparts, some endangered wild Atlantic salmon populations encounter during their marine stage large amounts of suspended sediments, which may act as a selective agent. We used microarrays to elucidate quantitative transcriptional differences between a domesticated salmon strain, a wild population and their first-generation hybrids during their marine life stage, to describe transcriptional responses to natural suspended sediments, and to test for adaptive genetic variation in plasticity relating to a history of natural exposure or nonexposure to suspended sediments. We identified 67 genes differing in transcription level among salmon groups. Among these genes, processes related to energy metabolism and ion homoeostasis were over-represented, while genes contributing to immunity and actin-/myosin-related processes were also involved in strain differentiation. DomesticM-bM-^@M-^Swild hybrids exhibited intermediate transcription patterns relative to their parents for two-thirds of all genes that differed between their parents; however, genes deviating from additivity tended to have similar levels to those expressed by the wild parent. Sediments induced increases in transcription levels of eight genes, some of which are known to contribute to external or intracellular damage mitigation. Although genetic variation in plasticity did not differ significantly between groups after correcting for multiple comparisons, two genes (metallothionein and glutathione reductase) tended to be more plastic in response to suspended sediments in wild and hybrid salmon, and merit further examination as candidate genes under natural selection. Salmon of three genotypes (strains: 1. wild (Stewiacke River salmon), 2. domesticated (Saint John River salmon), and 3. first generation hybrids between the two strains, were exposed to two environments (treatment: 1. suspended sediments, 2. control: clear water), using eight biological replicates (individuals) of each of the six experimental groups, summing up to 48 individuals, each individual has two technical replicates , each technical replicate has been labelled with a different dye, each technical replicate appears on a different array, dye swaps are equilibrated for arrays that combine individuals from different genotypes and for arrays that combine individuals from the same genotype but different environments. Technical replicates of individuals always appear once on arrays that compare between environments and once on arrays that compare among genotypes. In total there are 48 arrays.
Project description:Domestication has produced faster-growing strains of animals for use in agriculture, but selection has been applied with little knowledge of the underlying genetic changes that arose throughout the process. Mammals and birds have been domesticated for thousands of years whereas fish have been domesticated only recently; therefore, wild progenitor strains remain for comparison. Rainbow trout (Oncorhynchus mykiss) have undergone intensive selection and domesticated strains grow more rapidly than extant wild strains. To assess physiological pathways altered by domestication, whole-genome mRNA expression was measured in brain, muscle and liver of size-matched domestic and wild trout using a 16K (cGRASP) salmonid microarray. A large number of genes differed between strains, ranging from 3% of genes in brain to 9% in muscle. Domestic fish had more down-regulated genes in the brain relative to wild fish, whereas more genes were up-regulated in domestic liver and muscle. Relative to wild fish, there was a down-regulation of cell division and an up-regulation of structural genes in the brain of domestic fish. In liver from domestic fish, there was an up-regulation of genes related to transport with a down-regulation of lipid binding. Analysis of the functional categories for muscle indicated that most pathways, including pathways related to metabolism and catabolism, were up-regulated in domestic fish. Comparison of these results to other genomic studies on transgenic, domestic and wild salmonids suggests that similar physiological pathways are altered systemically to support faster rates of growth, regardless of the underlying genetic alteration that has caused the altered growth.
Project description:Domestication has produced faster-growing strains of animals for use in agriculture, but selection has been applied with little knowledge of the underlying genetic changes that arose throughout the process. Mammals and birds have been domesticated for thousands of years whereas fish have been domesticated only recently; therefore, wild progenitor strains remain for comparison. Rainbow trout (Oncorhynchus mykiss) have undergone intensive selection and domesticated strains grow more rapidly than extant wild strains. To assess physiological pathways altered by domestication, whole-genome mRNA expression was measured in brain, muscle and liver of size-matched domestic and wild trout using a 16K (cGRASP) salmonid microarray. A large number of genes differed between strains, ranging from 3% of genes in brain to 9% in muscle. Domestic fish had more down-regulated genes in the brain relative to wild fish, whereas more genes were up-regulated in domestic liver and muscle. Relative to wild fish, there was a down-regulation of cell division and an up-regulation of structural genes in the brain of domestic fish. In liver from domestic fish, there was an up-regulation of genes related to transport with a down-regulation of lipid binding. Analysis of the functional categories for muscle indicated that most pathways, including pathways related to metabolism and catabolism, were up-regulated in domestic fish. Comparison of these results to other genomic studies on transgenic, domestic and wild salmonids suggests that similar physiological pathways are altered systemically to support faster rates of growth, regardless of the underlying genetic alteration that has caused the altered growth.
Project description:Domestication has produced faster-growing strains of animals for use in agriculture, but selection has been applied with little knowledge of the underlying genetic changes that arose throughout the process. Mammals and birds have been domesticated for thousands of years whereas fish have been domesticated only recently; therefore, wild progenitor strains remain for comparison. Rainbow trout (Oncorhynchus mykiss) have undergone intensive selection and domesticated strains grow more rapidly than extant wild strains. To assess physiological pathways altered by domestication, whole-genome mRNA expression was measured in brain, muscle and liver of size-matched domestic and wild trout using a 16K (cGRASP) salmonid microarray. A large number of genes differed between strains, ranging from 3% of genes in brain to 9% in muscle. Domestic fish had more down-regulated genes in the brain relative to wild fish, whereas more genes were up-regulated in domestic liver and muscle. Relative to wild fish, there was a down-regulation of cell division and an up-regulation of structural genes in the brain of domestic fish. In liver from domestic fish, there was an up-regulation of genes related to transport with a down-regulation of lipid binding. Analysis of the functional categories for muscle indicated that most pathways, including pathways related to metabolism and catabolism, were up-regulated in domestic fish. Comparison of these results to other genomic studies on transgenic, domestic and wild salmonids suggests that similar physiological pathways are altered systemically to support faster rates of growth, regardless of the underlying genetic alteration that has caused the altered growth.
Project description:Abrupt environment changes can elicit an array of genetic effects. However, many of these effects can be overlooked by functional genomic studies conducted in static laboratory conditions. We studied the transcriptomic responses of Caenorhabditis elegans under single generation exposures to drastically different culturing conditions. In our experimental scheme, P0 worms were maintained on terrestrial environments (agar plates), F1 in aquatic cultures, and F2 back to terrestrial environments. The laboratory N2 strain and the wild isolate AB1 strain were utilized to examine how the genotype contributes to the transcriptome dynamics. Significant variations were found in the gene expressions between the “domesticated” laboratory strain and the wild isolate in the different environments. The results showed that 20% - 27% of the transcriptional responses to the environment changes were transmitted to the subsequent generation. In aquatic conditions, the domesticated strain showed differential gene expression particularly for the genes functioning in the reproductive system and the cuticle development. In accordance with the transcriptomic responses, phenotypic abnormalities were detected in the germline and cuticle of the domesticated strain. Further studies showed that distinct groups of genes are exclusively expressed under specific environmental conditions, and many of these genes previously lacked supporting biochemical evidence.