Project description:The sustainable development of modern aquaculture must rely on a significant reduction of the fish meal (FM) used in aquafeed formulations. However, FM substitution with alternative ingredients in diets for carnivorous fish species often showed reduced nutrient absorption, significantly perturbed metabolisms and histological changes at both hepatic and intestinal level. In the present study, adult rainbow trout (Oncorhynchus mykiss) were fed three different experimental aquafeed formulations. A control diet with higher FM content (27.3%) than two test formulations in which fish meal was substituted with two more sustainable and promising alternatives: insect meal (Hermetia illucens larvae=10.1%, FM=11.6%) and poultry by-products meal (PBM=14.8%; FM=11.7%). Combined metabolomics and proteomics analyses of fish liver, together with histological examination of liver and intestine demonstrated that a well balanced formulation of nutrients in the three diets allowed high metabolic compatibility of either substitutions, paving the way for innovative and sustainable use of novel raw materials for the fish feed industry. Results show that the main metabolic pathways of nutrient absorption and catabolism were essentially unaltered by alternative feed ingredients, and also histological alterations were negligible. It is demonstrated that substitution of fish meal with sustainable alternatives does not impact on fish metabolism, given proper efforts are put in fulfilling nutritional requirements of rainbow trout.
Project description:Rainbow trout (Oncorhynchus mykiss) and other salmonids are piscivorous fish. In aquaculture, fish-based feed ingredients are rapidly becoming unsustainable due to increased demand and diminishing supply. Total replacement of fishmeal with plant proteins causes severe intestinal enteritis, leading to reduced growth and lower feed efficiency. Through selective breeding, we have developed a strain of rainbow trout that does not develop distal intestine enteritis when reared on a high soy plant protein-based feed and also shows increased growth compared to other strains. Since central metabolism plays a major role in dietary alterations, and as growth was a major factor in the selection program, both muscle and liver gene expression were examined for differential regulation between commercial and selected trout strains when fed alternative diets. After three months of rearing on either a fishmeal (FM) or plant protein-based (PM) diet, muscle and liver tissues from a domestic non-selected strain (House Creek; develops enteritis) and the selected strain (ARS-KO; no enteritis) were extracted and prepped for Illumina RNA-seq. Raw reads were screened for quality then aligned to the rainbow trout transcriptome. Read-counts were used to assess differential expression between strains and treatments. Significant differentially expressed genes between comparisons were assessed.
Project description:The sustainable growth of fish aquaculture will require the procurement of non-marine feed sources. Glycerol is a potential feed supplement whose metabolism may spare the catabolism of dietary amino acids, thereby extending the use of the feed protein to other physiological functions such as growth. In the present study, the effects of dietary glycerol supplementation on the muscle and liver metabolomes of rainbow trout (Oncorhynchus mykiss) and European seabass (Dicentrarchus labrax) were evaluated. Fish juveniles were fed diets with 0%, 2.5%, and 5% glycerol. Muscle and liver aqueous fractions were extracted and 1H NMR spectra were acquired. Metabolite profiles derived from the 1H NMR signals were assessed using univariate and multivariate statistical analyses. The adenylate energy charge was determined in the muscle. For both species, the muscle metabolite profile showed more variability compared to that of the liver and was most perturbed by the 5.0% glycerol diet. For the liver metabolite profile, rainbow trout showed fewer differences compared to European seabass. No differences were observed in energy charge between experimental groups for either species. Thus, rainbow trout appeared to be less susceptible to tissue metabolite perturbations, compared to seabass, when the diet was supplemented with up to 5% glycerol.
Project description: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) 1.2% choline supplementation (High Choline: 9248 ppm choline). Six all-female rainbow trout families were fed experimental diets beginning 18 months post-hatch until spawning; their offspring were fed a commercial diet. Experimental broodstock diet did not affect overall choline, fatty acid, or amino acid content in the oocytes (p > 0.05), apart from tyrosine (p ≤ 0.05). Offspring body weights from the High and Low Choline diets did not differ from those in the Medium Choline diet (p > 0.05); however, family-by-diet and sire-by-diet interactions on offspring growth were detected (p ≤ 0.05). The High Choline diet did not improve growth performance in the six broodstock families at final harvest (520-days post-hatch, or dph). Numerous genes associated with muscle development and lipid metabolism were identified, including myosin, troponin C, and fatty acid binding proteins, which were associated with key signaling pathways of lipid metabolism, muscle cell development, muscle cell proliferation, and muscle cell differentiation. These findings indicate that supplementing broodstock diets with choline does regulate expression of genes related to growth and nutrient partitioning but does not lead to growth benefits in rainbow trout families selected for disease resistance.
Project description:As an important cold-water economic fish species, rainbow trout (Oncorhynchus mykiss) exhibits several intra-specific variation in skin pigmentation that can give rise to distinctive phenotypes, and wild-type rainbow trout with black skin (WR) and yellow mutant rainbow trout with yellow skin (YR) are the major two types in the farms, whose distinct skin colors make them suitable model for elucidating the skin pigmentation process. Skin color as a key indicator for selection in rainbow trout farming as well as has a strong visual impact on the consumer when rainbow trout are marketed. Previously, extensive studies have been conducted on skin color in rainbow trout, including the observation of skin spots and the expression analysis of some important pigment genes. However, up to date, no studies have systematically examined the molecular regulation mechanism of skin color difference between WR and YR through a high throughput method. Therefore, the aim of this study was to reveal the molecular regulation mechanism of skin color difference between these two strains at the mRNA and miRNA transcriptome level, and candidate genes, miRNAs and miRNA-mRNA pairs that may be responsible for rainbow trout albinism were obtained.
Project description:Rainbow trout (Oncorhynchus mykiss) were fed during 4 weeks with either a control diet or an immunostimulant diet and then injected with LPS to investigate the effect of dietary immunostimulation in the portals of entry, intestine and gills, using a salmonid-specific microarray platform enriched with immune-related genes. IS-diet feeding significantly changed transcriptomic expression profiles in response to LPS: significant changes in genes and functional GO categories related to remodeling processes and antigen presentation were different for both diets. The results revealed that one of the main effects of IS-diets in trout is the increase of genes involved in antigen recognition and in adaptive immunity. Keywords: gills, intestine, immunostimulats, transcriptomic response, trout
Project description:Infectious hematopoietic necrosis virus (IHNV) can cause widespread death of rainbow trout (Oncorhynchus mykiss), understanding the molecular mechanisms that occur in the rainbow trout in response to IHNV infection will be useful to decrease IHN-related morbidity and mortality in trout aquaculture. However, the molecular mechanisms of rainbow trout in response to IHNV are very limited. This study performed analysis of mRNAs and miRNAs based on RNA-seq technology on the intestine of rainbow trout infected with IHNV and control. There were 80 differentially expressed miRNAs that regulated 3355 target mRNAs, which overlapped with differentially expressed mRNAs obtained from RNA-seq. The expression patterns of DEGs and miRNAs differentially expressed were validated by qRT-PCR. GO enrichment and KEGG pathway analyses of the potential target genes of the DE miRNAs, revealed DEGs were mainly enriched in immune-related pathways such as Toll-like receptor signaling pathway, RIG-I-like receptor signaling pathway and IL-17 signaling pathway. These findings improve our understanding of the molecular mechanisms of IHNV infection. The study analyzed the immune regulatory target gene pairs and signal pathways of rainbow trout intestine against IHNV infection at the transcriptional level, and provided basic data for the study of rainbow trout against IHNV immune regulatory.
Project description:Rainbow trout (Oncorhynchus mykiss) is an important aquaculture fish species that is farmed worldwide, and it is also the most widely cultivated cold water fish in China. This species, a member of the salmonidae family, is an ideal model organism for studying the immune system in fish. Two phenotypes of rainbow trout are widely cultured; wild-type rainbow trout with black skin (WR_S) and yellow mutant rainbow trout with yellow skin (YR_S). Fish skin is an important immune organ, however, little is known about the differences in skin immunity between WR_S and YR_S in a natural flowing water pond aquaculture environment, and very few studies were conducted to investigate the ceRNA mechanism for fish skin.