Remodeling of the epigenetic landscape in rainbow trout, Oncorhynchus mykiss, offspring in response to maternal choline intake.

This project focused on evaluating the effects of maternal dietary choline intake on global DNA methylation profiles and related transcriptional changes in rainbow trout offspring. Three experimental diets were formulated to test different levels of choline intake: (a) 2065 ppm choline (Low Choline, 0 % supplementation), (b) 5657 ppm choline (Medium Choline, 0.6 % supplementation), and (c) 9248 ppm choline (High Choline, 1.

Profiling growth performance, insulin-like growth factors, and IGF-binding proteins in rainbow trout lacking IGFBP-2b.

Insulin-like growth factor-binding proteins (IGFBPs) regulate insulin-like growth factor (IGF) signaling, but IGFBP-specific functions are not well characterized in fishes. A line of rainbow trout () lacking a functional IGFBP-2b was produced using gene editing and subsequent breeding to an F2 generation. This loss-of-function model [IGFBP-2b knockout (2bKO)] was subjected to either continuous feeding or feed deprivation (3 wk) followed by refeeding (1 wk).

Direct actions of growth hormone in rainbow trout, Oncorhynchus mykiss, skeletal muscle cells in vitro.

The growth hormone (GH)-insulin-like growth factor-1 (IGF-1) system regulates skeletal muscle growth and function. GH has a major function of targeting the liver to regulate IGF-1 production and release, and IGF-1 mediates the primary anabolic action of GH on growth. However, skeletal muscle is a target tissue of GH as evidenced by dynamic GH receptor expression, but it is unclear if GH elicits any direct actions on extrahepatic tissues as it is difficult to distinguish the effects of IGF-1 from GH.

Maternal dietary choline levels cause transcriptome shift due to genotype-by-diet interactions in rainbow trout (Oncorhynchus mykiss).

The objective of this study was to identify metabolic regulatory mechanisms affected by choline availability in rainbow trout (Oncorhynchus mykiss) broodstock diets associated with increased offspring growth performance. Three customized diets were formulated to have different levels of choline: (a) 0 % choline supplementation (Low Choline: 2065 ppm choline), (b) 0.6 % choline supplementation (Medium Choline: 5657 ppm choline), and (c) 1.

Leptin Receptor Deficiency Results in Hyperphagia and Increased Fatty Acid Mobilization during Fasting in Rainbow Trout ().

Leptin is a pleiotropic hormone known for regulating appetite and metabolism. To characterize the role of leptin signaling in rainbow trout, we used CRISPR/Cas9 genome editing to disrupt the leptin receptor (LepR) genes, and . We compared wildtype (WT) and mutant fish that were either fed to satiation or feed deprived for six weeks.

Characterization of a Leptin Receptor Paralog and Its Response to Fasting in Rainbow Trout ().

Leptin is a cytokine that regulates appetite and energy expenditure, where in fishes it is primarily produced in the liver and acts to mobilize carbohydrates. Most fishes have only one leptin receptor (LepR/LepRA1), however, paralogs have recently been documented in a few species. Here we reveal a second leptin receptor (LepRA2) in rainbow trout that is 77% similar to trout LepRA1.

Replacing fish oil and astaxanthin by microalgal sources produced different metabolic responses in juvenile rainbow trout fed 2 types of practical diets.

Dietary fish oil supplementation provides n-3 long-chained polyunsaturated fatty acids for supporting fish growth and metabolism and enriching fillet with eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; c22:6n-3). Two experiments were performed as a 3 × 2 factorial arrangement of dietary treatments for 16 wk to determine effects and mechanisms of replacing 0%, 50%, and 100% fish oil with DHA-rich microalgae in combination with synthetic vs. microalgal source of astaxanthin in plant protein meal (PM)- or fishmeal (FM)- based diets for juvenile rainbow trout (Oncorhynchus mykiss).

Molecular Mechanisms Regulating Muscle Plasticity in Fish.

Growth rates in fish are largely dependent on genetic and environmental factors, of which the latter can be highly variable throughout development. For this reason, muscle growth in fish is particularly dynamic as muscle structure and function can be altered by environmental conditions, a concept referred to as muscle plasticity. Myogenic regulatory factors (MRFs) like Myogenin, MyoD, and Pax7 control the myogenic mechanisms regulating quiescent muscle cell maintenance, proliferation, and differentiation, critical processes central for muscle plasticity.

Supplemental Microalgal DHA and Astaxanthin Affect Astaxanthin Metabolism and Redox Status of Juvenile Rainbow Trout.

Microalgal docosahexaenoic acid (DHA) and astaxanthin (AST) may substitute for fish oil and synthetic AST in aquafeeds. This study explored the effects and mechanisms of those substitutions on AST metabolism and redox status of rainbow trout fed plant protein meal (PM)- or fishmeal (FM)-based diets. Two parallel experiments (PM vs.

Compensatory Response of the Somatotropic Axis from IGFBP-2b Gene Editing in Rainbow Trout ().

Rainbow trout with gene editing-induced reductions in serum insulin-like growth factor binding protein (IGFBP)-2b exhibit similar growth performance compared to fish without IGFBP-2b gene disruption. The objective of this study is to determine how the components of the insulin-like growth factor (IGF)/IGFBP system respond to a reduction in serum IGFBP-2b abundance. Editing the IGFBP-2b genes in rainbow trout resulted in an 83% decrease in serum IGFBP-2b in mutants.

Distinct microbial assemblages associated with genetic selection for high- and low- muscle yield in rainbow trout.

Background: Fish gut microbial assemblages play a crucial role in the growth rate, metabolism, and immunity of the host. We hypothesized that the gut microbiota of rainbow trout was correlated with breeding program based genetic selection for muscle yield. To test this hypothesis, fecal samples from 19 fish representing an F2 high-muscle genetic line (ARS-FY-H) and 20 fish representing an F1 low-muscle yield genetic line (ARS-FY-L) were chosen for microbiota profiling using the 16S rRNA gene.

Hepatic Fatty Acid and Transcriptome Profiles during the Transition from Vegetable- to Fish Oil-Based Diets in Rainbow Trout (Oncorhynchus mykiss).

A finishing diet strategy is effective at increasing fillet long-chain n-3 fatty acid content in fish consuming sustainable plant oil-based diets. This study investigates the outcomes of a fish oil finishing diet upon the hepatic fatty acid and transcriptome profile in rainbow trout (Oncorhynchus mykiss). Fish were placed on one of three feeding treatments: (1) FO: a fish oil (FO) diet for 20 weeks, (2) VO/FO: a vegetable oil (VO) diet during weeks 1-12 then the FO diet for 8 weeks, or (3) VO/fd/FO: the VO diet between weeks 1-12, 2 weeks of feed deprivation, then the FO diet for 6 weeks.

Transcriptomic Response to Selective Breeding for Fast Growth in Rainbow Trout (Oncorhynchus mykiss).

Genetic improvement for faster growth is a conventional approach to increase growth rates in aquaculture species; however, the genetic and physiological factors regulating growth performance in fish are not fully characterized. The objective of this study was to identify physiological mechanisms associated with faster growth rates by comparing the liver and muscle transcriptome of a rainbow trout line selectively bred for fast growth (growth line, GL) and a contemporary randomly mated control line (synthetic control, SC) from the same selective breeding program. A third genetic line from a commercial egg supplier (commercial A, CA) was also included to characterize differences in gene expression profiles between populations.

Analysis of the fecal microbiota of fast- and slow-growing rainbow trout (Oncorhynchus mykiss).

Background: Diverse microbial communities colonizing the intestine of fish contribute to their growth, digestion, nutrition, and immune function. We hypothesized that fecal samples representing the gut microbiota of rainbow trout could be associated with differential growth rates observed in fish breeding programs. If true, harnessing the functionality of this microbiota can improve the profitability of aquaculture.

Essential amino acids exhibit variable effects on protein degradation in rainbow trout (Oncorhynchus mykiss) primary myocytes.

The functional role of amino acids as regulators of protein degradation was investigated using primary myogenic precursor cell culture as in vitro model of rainbow trout white muscle. Seven-day old myocytes were starved of amino acids for two hours then exposed to media that contained amino acid treatments, during which protein degradation rates were analyzed over five hours by measuring cellular release of H-tyrosine. Increasing concentrations of essential amino acids (EAA) reduced protein degradation rates; this effect was dose-dependent within the physiological range found in plasma.

Editing the duplicated insulin-like growth factor binding protein-2b gene in rainbow trout (Oncorhynchus mykiss).

In salmonids, the majority of circulating insulin-like growth factor-I (IGF-I) is bound to IGF binding proteins (IGFBP), with IGFBP-2b being the most abundant in circulation. We used CRISPR/Cas9 methodology to disrupt expression of a functional IGFBP-2b protein by co-targeting for gene editing IGFBP-2b1 and IGFBP-2b2 subtypes, which represent salmonid-specific gene duplicates. Twenty-four rainbow trout were produced with mutations in the IGFBP-2b1 and IGFBP-2b2 genes.

Physiological and Molecular Mechanisms of Methionine Restriction.

Methionine restriction (MR) has been studied extensively over the last 25 years for its role in altering metabolic hallmarks of disease. Animals subjected to MR, display changes in metabolic flexibility demonstrated by increases in energy expenditure, glucose tolerance, and lifespan. These changes have been well characterized in a number of model systems and significant progress has been made in understanding how hepatic fibroblast growth factor 21 links MR to several components of its metabolic phenotype.

Effects of cooking techniques on fatty acid and oxylipin content of farmed rainbow trout ().

The aim of this study was to investigate the effect of various cooking techniques on the fatty acid and oxylipin content of farmed rainbow trout. Rainbow trout is an excellent source of long-chain omega-3 (-3) polyunsaturated fatty acids (PUFA) which have beneficial health effects. Fillets of 2-year-old farmed rainbow trout were baked, broiled, microwaved, or pan-fried in corn (CO), canola (CaO), peanut (PO), or high oleic sunflower oil (HOSO).

Comprehensive analysis of lncRNAs and mRNAs in skeletal muscle of rainbow trout (Oncorhynchus mykiss) exposed to estradiol.

Estradiol (E2) is a steroid hormone that negatively affects muscle growth in rainbow trout (Oncorhynchus mykiss), but the mechanisms directing with this response are not fully understood. To better characterize the effects of E2 in muscle, we identified differentially regulated mRNAs and lncRNAs in juvenile rainbow trout exposed to E2. Here, we performed next-generation RNA sequencing and comprehensive bioinformatics analyses to characterize the transcriptome profiles, including mRNAs and long noncoding RNAs (lncRNAs), in skeletal muscle of rainbow trout injected with E2.

17β-Estradiol Increases Non-CpG Methylation in Exon 1 of the Rainbow Trout (Oncorhynchus mykiss) MyoD Gene.

MyoD is an important myogenic transcription factor necessary for the differentiation of myogenic precursor cells (MPC) to form mature myotubes, a process essential for muscle growth. Epigenetic markers such as CpH methylation are known gene regulators that are important for the differentiation process. In this study, we investigated whether DNA methylation is a potential mechanism associated with the ability of 17β-estradiol (E2) to reduce MyoD gene expression and muscle growth in rainbow trout.

Dataset of proinflammatory cytokine and cytokine receptor gene expression in rainbow trout () measured using a novel GeXP multiplex, RT-PCR assay.

A GeXP multiplex, RT-PCR assay was developed and optimized that simultaneously measures expression of a suite of immune-relevant genes in rainbow trout (), concentrating on tumor necrosis factor and interleukin-1 ligand/receptor systems and acute phase response genes. The dataset includes expression values for , , , , , (e3-5), (e9-11), , , , , , , , , , , , and . Gene expression was measured at four time-points post-challenge in both a resistant line (ARS-Fp-R) and a susceptible line (ARS-Fp-S) of rainbow trout.

Estradiol regulates expression of miRNAs associated with myogenesis in rainbow trout.

17β-Estradiol (E2) is a steroid hormone that negatively affects muscle growth in rainbow trout, but the mechanism associated with this response is not fully understood. To better characterize the effects of E2 on muscle, we identified differentially regulated microRNAs (miRNAs) and muscle atrophy-related transcripts in juvenile rainbow trout exposed to E2. Small RNA-Seq analysis of E2-treated vs.

Genome-Wide Association Study for Identifying Loci that Affect Fillet Yield, Carcass, and Body Weight Traits in Rainbow Trout ().

Fillet yield (FY, %) is an economically-important trait in rainbow trout aquaculture that affects production efficiency. Despite that, FY has received little attention in breeding programs because it is difficult to measure on a large number of fish and cannot be directly measured on breeding candidates. The recent development of a high-density SNP array for rainbow trout has provided the needed tool for studying the underlying genetic architecture of this trait.