Project description:We used gene expression accompanied by physical characteristics and gill Na+/K+-ATPase activity to analyze physiological differences associated with two life history variations of juvenile fall Chinook Salmon in the Snake River basin. Subyearlings originating in the Snake River typically migrate seaward as subyearlings, whereas many subyearlings from the Clearwater River delay seaward migration during summer and complete seaward migration the following spring as yearlings. We examined gill Na+/K+-ATPase activity and gene expression of subyearlings at different times during rearing and seaward emigration. Natural-origin Snake River subyearlings rearing under an increasing photoperiod and seasonally increasing temperatures showed a typical increasing pattern of parr to smolt gill Na+/K+-ATPase activity development, which then declined into autumn. In contrast, Clearwater River subyearlings that had experienced cooler temperatures showed no pattern of increasing gill Na+/K+-ATPase activities and were not different from parr. Liver transcription of genes involved in DNA repair and binding, the cell cycle, metabolism (steroid, fatty acid and other metabolic pathways) iron homeostasis, heme and oxygen binding, the immune response, and male sexual development were enriched amongst genes differentially expressed between Snake River parr versus smolts. Gene expression results confirmed that Clearwater River subyearlings were parr-like in their physiological status. By autumn, subyearlings had low gill Na+/K+-ATPase activities despite their large size and external smolt characteristics. We suggest that environmental factors like temperature and photoperiod influence subyearling physiological status in each river that ultimately dictates juvenile life history pathways. Non-migrating and migrating natural subyearling fall Chinook salmon were collected from the Snake River. Non-migrating natural subyearling fall Chinook salmon were collected from the Clearwater River. Twelve fish were collected at each of four different time points for a total of 48 fish. Total RNA was extracted from the liver of each fish. Equal amounts of RNA from three fish were pooled to create four pools of RNA per time point. Each RNA pool was hybridized to an array for a total of 16 arrays with four arrays per time point.
Project description:Thermal stress is a serious and growing challenge facing Chinook salmon (Oncorhynchus tshawytscha) living in the southern portion of their native range. River alterations have increased the likelihood that juveniles will be exposed to warm water temperatures during their freshwater life stage, which can negatively impact survival, growth, and development and poses a threat to dwindling salmon populations. In order to better understand how acute thermal stress affects the biology of salmon, we performed a transcriptional analysis of gill tissue from unacclimated Chinook juveniles exposed to short periods at water temperatures ranging from ideal to potentially lethal. Reverse transcribed RNA libraries were sequenced on the Illumina HiSeq2000 platform and a de novo reference transcriptome was created. Differentially expressed transcripts were annotated using Blast2GO and relevant gene clusters were identified.
Project description:Chinook salmon (Oncorhynchus tshawytscha) display the greatest variability of return times to freshwater of all Pacific salmon. Populations return to freshwater for spawning at many different times of year, resulting in segregated populations that may use differing molecular pathways for these large behavioral and physiological differences. Using a population of Chinook from California’s Central Valley, we sought to generate novel expressed sequences using Long Serial Analysis of Gene Expression (LongSAGE). We constructed three LongSAGE libraries from brains of samples caught in the spring and fall in freshwater and from the ocean. Using cDNA libraries from Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), we were able to assign 59% of putatively differentially expressed tags to genes. Additionally, we tested the expression levels of seven genes, indicated by LongSAGE to be putatively differentially expressed between the fall and spring, and found none significantly differentially expressed. This study is the first to apply LongSAGE to salmon and provides a framework for conducting future research on gene expression differences between Chinook salmon of different populations, as well as underlying mechanisms of differing physiology and behavior. Keywords: seasonal difference
Project description:Chinook salmon (Oncorhynchus tshawytscha) display the greatest variability of return times to freshwater of all Pacific salmon. Populations return to freshwater for spawning at many different times of year, resulting in segregated populations that may use differing molecular pathways for these large behavioral and physiological differences. Using a population of Chinook from California’s Central Valley, we sought to generate novel expressed sequences using Long Serial Analysis of Gene Expression (LongSAGE). We constructed three LongSAGE libraries from brains of samples caught in the spring and fall in freshwater and from the ocean. Using cDNA libraries from Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), we were able to assign 59% of putatively differentially expressed tags to genes. Additionally, we tested the expression levels of seven genes, indicated by LongSAGE to be putatively differentially expressed between the fall and spring, and found none significantly differentially expressed. This study is the first to apply LongSAGE to salmon and provides a framework for conducting future research on gene expression differences between Chinook salmon of different populations, as well as underlying mechanisms of differing physiology and behavior. Keywords: seasonal difference Single individuals were used to construct each LongSAGE library. The fall, spring and ocean samples were then compared between each other and examined for differences in the number of tags observed.
Project description:Traditionally, the study of evolution has focused on heritable variation, because selection on non-heritable phenotypic variation was deemed non-important for its inability to cause evolutionary responses such as diversification of lineages. Recently however, it has been suggested that also environmentally induced phenotypic variation such as phenotypic plasticity can play an important role in adaptive responses resulting in diversification. The purpose of this study is to investigate the importance of phenotypic plasticity for the diversification of lineages, using life history, morphological traits, and genomic profiling during post embryonic development in plastic and non-plastic genotypes of the common frog Rana temporaria.
Project description:The availability of a reference genome assembly for Atlantic salmon, Salmo salar, SNP genotyping platforms and low cost sequencing is enhancing the understanding of both life history and production-related traits in this important commercial species. We collected and analysed transcriptomes from selected tissues of Atlantic salmon to inform future functional and comparative genomics studies. Messenger RNA (mRNA) was isolated from brain, pituitary, ovary and liver before Illumina sequencing produced a total of 640 million 150-bp paired-end reads. Following read mapping, feature counting and normalization, cluster analysis identified genes highly expressed in a tissue-specific manner. Functional profiling identified gene clusters describing the unique functions of each tissue. Moreover, highly-expressed transcription factors present in each tissue-specific gene cluster were identified. The data and analysis presented are relevant to the emerging Functional Annotation of All Salmonid Genomes (FAASG) initiative that is seeking to develop a detailed understanding of both salmonid evolution and the genomic elements that drive gene expression and regulation.
Project description:Traditionally, the study of evolution has focused on heritable variation, because selection on non-heritable phenotypic variation was deemed non-important for its inability to cause evolutionary responses such as diversification of lineages. Recently however, it has been suggested that also environmentally induced phenotypic variation such as phenotypic plasticity can play an important role in adaptive responses resulting in diversification. The purpose of this study is to investigate the importance of phenotypic plasticity for the diversification of lineages, using life history, morphological traits, and genomic profiling during post embryonic development in plastic and non-plastic genotypes of the common frog Rana temporaria. Six animals each originating from four different islands were reared in either constant or reduced water conditions and hepatic mRNA levels of Gosner stage 37 animals evaluated by MAGEX DNA array analysis.
Project description:Fish in use in aquaculture display large variation in gamete biology. To reach better understanding around this issue, this study aims at identifying if “egg life history traits” can be hidden in egg transcriptomes. To pursue this, salmon and cod eggs were selected due to their largely differencing phenotypes (size, robustness, fresh/marine). An oligo microarray analysis was performed on ovulated eggs from cod (~23 000 genes, n=8) and salmon (~44 000 genes, n=7). The arrays were normalized to a similar spectrum for both arrays. Both arrays were re-annotated based on official gene symbol to retrieve an orthologous KEGG annotation, in salmon and cod arrays this represented 14009 and 7437 genes respectively. The probe linked to the highest gene expression for that particular KEGG annotation was used to compare expression between species. Differential expression was calculated for genes that had an annotation with score > 300, resulting in a total of 2354 KEGG annotations (genes) being differently expressed between the species. The most differentially expressed genes in salmon and cod (FD≥2), were used to reveal pathways that were overrepresented in the eggs of each species. This analysis revealed that immune, signal transduction, and excretory related pathways were overrepresented in salmon compared to cod. The most overrepresented pathways in cod were related to regulation of genetic information processing and metabolism. To conclude this analysis clearly point at some distinct transcriptome repertoires for cod and salmon and that these differences may explain some of the species-specific biological features for salmon and cod eggs.