Lysine supplement benefits the growth performance, protein synthesis, and muscle development of Megalobrama amblycephala fed diets with fish meal replaced by rice protein concentrate

Green Microfluidic Method for Sustainable and High-Speed Analysis of Basic Amino Acids in Nutritional Supplements

Amino acids (AAs) have broad nutritional, therapeutic, and medical significance and thus are one of the most common active ingredients of nutritional supplements. Analytical strategies for determining AAs are high-priced and often limited to methods that require modification of AA polarity or incorporation of an aromatic moiety. The aim of this work was to develop a new method for the determination of L-arginine, L-ornithine, and L-lysine on low-cost microchip electrophoresis instrumentation conjugated with capacitively coupled contactless conductivity detection. A solution consisting of 0.3 M acetic acid and 1 × 10-5 M iminodiacetic acid has been identified as the optimal background electrolyte, ensuring the shortest possible analysis time. The short migration times of amino acids (t ≤ 64 s) and method simplicity resulted in high analysis throughput with high precision and linearity (R2≥ 0.9971). The limit of detection values ranged from 0.15 to 0.19 × 10-6 M. The accuracy of the proposed method was confirmed by recovery measurements. The results were compared with CE-UV-VIS and HPLC-DAD methods and showed good agreement. This work represents the first successful demonstration of the ME-C4D analysis of L-arginine, L-ornithine, and L-lysine in real samples.

Integrated metabolomics and proteomics analysis to understand muscle atrophy resistance in hibernating Spermophilus dauricus

Hibernating Spermophilus dauricus experiences minor muscle atrophy, which is an attractive anti-disuse muscle atrophy model. Integrated metabolomics and proteomics analysis was performed on the hibernating S. dauricus during the pre-hibernation (PRE) stage, torpor (TOR) stage, interbout arousal (IBA) stage, and post-hibernation (POST) stage. Time course stage transition-based (TOR vs. PRE, IBA vs. TOR, POST vs. IBA) differential expression analysis was performed based on the R limma package. A total of 14 co-differential metabolites were detected. Among these, l-cystathionine, l-proline, ketoleucine, serine, and 1-Hydroxy-3,6,7-Trimethoxy-2, 8-Diprenylxanthone demonstrated the highest levels in the TOR stage; Beta-Nicotinamide adenine dinucleotide, Dihydrozeatin, Pannaric acid, and Propionylcarnitine demonstrated the highest levels in the IBA stage; Adrenosterone, PS (18:0/14,15-EpETE), S-Carboxymethylcysteine, TxB2, and 3-Phenoxybenzylalcohol demonstrated the highest levels in the POST stage. Kyoto Encyclopedia of Genes and Genomes pathways annotation analysis indicated that biosynthesis of amino acids, ATP-binding cassette transporters, and cysteine and methionine metabolism were co-differential metabolism pathways during the different stages of hibernation. The stage-specific metabolism processes and integrated enzyme-centered metabolism networks in the different stages were also deciphered. Overall, our findings suggest that (1) the periodic change of proline, ketoleucine, and serine contributes to the hindlimb lean tissue preservation; and (2) key metabolites related to the biosynthesis of amino acids, ATP-binding cassette transporters, and cysteine and methionine metabolism may be associated with muscle atrophy resistance. In conclusion, our co-differential metabolites, co-differential metabolism pathways, stage-specific metabolism pathways, and integrated enzyme-centered metabolism networks are informative for biologists to generate hypotheses for functional analyses to perturb disuse-induced muscle atrophy.

Terrestrial Compound Protein Replacing Dietary Fishmeal Improved Digestive Enzyme Activity, Immune Response, Intestinal Microflora Composition, and Protein Metabolism of Golden Pompano (Trachinotus ovatus)

Terrestrial compound protein (Cpro) can be potentially used to replace fishmeal (FM) in the marine carnivorous teleost, golden pompano (Trachinotus ovatus). Four isonitrogenous (45%) and isolipidic (12%) diets named FM30, AP80, PP80, and CP80 were formulated. FM30 (control) contained 30% FM and 25% basic protein, while AP80, PP80, and CP80 only contained 6% FM, where 80% FM and 25% basic protein of control diet were completely replaced by animal protein, plant protein, and Cpro, respectively. After golden pompano juveniles (initial weight: 10.32 ± 0.09 g) were, respectively, fed the four diets in floating sea cages for 10 weeks, the growth performance, intestinal digestive enzyme activity, and immune responses, protein metabolism indices of the CP80 group were similar to or better than those of the FM30 group (P > 0.05), and significantly better than those of the AP80 and PP80 groups. Specifically, the weight gain (WG), feed conversion ratio (FCR), activity of alanine transaminase (ALT), growth hormone (GH), and insulin-like growth factor-1 (IGF-1) contents of serum, mRNA level of interleukin-10 (il-10), zonula occludens-2 (zo-2), claudin-3, claudin-12, and eukaryotic translation initiation factor 4G (eif4g) were significantly higher, and the activity of α-amylase (AMS), lipase (LPS) in the foregut and midgut, interleukin-8 (il-8) expression in the intestine was significantly lower than that in the CP80 group, compared with those in AP80 and PP80 groups (P < 0.05). Moreover, the intestinal microflora composition of golden pompano fed with the CP80 diet was improved. Specifically, at the phylum level, the relative abundance of harmful bacterial strains cyanobacteria and TM7 of CP80 group was similar to those of FM30 group (P > 0.05), but was significantly lower than those of AP80 and PP80 groups (P < 0.05). At the genus level, the beneficial bacterial strains Agrobacterium and Blantia of CP80 group were also similar to those of FM30 group (P < 0.05), which were significantly higher than those of AP80 and PP80 groups, but the beneficial bacterial strains Bifidobacterium and Devosia of CP80 group were significantly higher than that in the other groups (P < 0.05). Besides, in diet CP80, the contents of amino acids and anti-nutritional factor, as well as the in vitro digestion rate were comparable to those of FM30, and the anti-nutritional factor content was between AP80 and PP80; total essential amino acids (EAAs) and methionine contents were higher than those in AP80, the glycine content was higher than that in PP80. Taken together, these results indicated that the CP80 diet had better amino acid composition and relatively low content of anti-nutritional factors, as well as high-digestion rate, and thus leads to the fish fed CP80 displaying improved effects in digestive enzyme activity, immune response, protein metabolism, and intestinal microbiota composition, which may be the important reasons to explain why that 80% of FM can be replaced by Cpro in the diet of golden pompano.

Molecular Characterization of LKB1 of Triploid Crucian Carp and Its Regulation on Muscle Growth and Quality

Liver Kinase B1 (LKB1) is a serine/threonine kinase that can regulate energy metabolism and skeletal muscle growth. In the present study, LKB1 cDNA of triploid crucian carp (Carassius auratus) was cloned. The cDNA contains a complete open reading frame (ORF), with a length of 1326 bp, encoding 442 amino acids. Phylogenetic tree analysis showed that the LKB1 amino acid sequence of the triploid crucian carp had a high sequence similarity and identity with carp (Cyprinus carpio). Tissue expression analysis revealed that LKB1 was widely expressed in various tissues. LKB1 expressions in the brain were highest, followed by kidney and muscle. In the short-term LKB1 activator and inhibitor injection experiment, when LKB1 was activated for 72 h, expressions of myogenic differentiation (MyoD), muscle regulatory factor (MRF4), myogenic factor (MyoG) and myostatin 1 (MSTN1) were markedly elevated and the content of inosine monophosphate (IMP) in muscle was significantly increased. When LKB1 was inhibited for 72 h, expressions of MyoD, MyoG, MRF4 and MSTN1 were markedly decreased. The long-term injection experiment of the LKB1 activator revealed that, when LKB1 was activated for 15 days, its muscle fibers were significantly larger and tighter than the control group. In texture profile analysis, it showed smaller hardness and adhesion, greater elasticity and chewiness. Contrastingly, when LKB1 was inhibited for 9 days, its muscle fibers were significantly smaller, while the gap between muscle fibers was significantly larger. Texture profile analysis showed that adhesion was significantly higher than the control group. A feeding trial on triploid crucian carp showed that with dietary lysine-glutamate dipeptide concentration increasing, the expression of the LKB1 gene gradually increased and was highest when dipeptide concentration was 1.6%. These findings may provide new insights into the effects of LKB1 on fish skeletal muscle growth and muscle quality, and will provide a potential application value in improvement of aquaculture feed formula.

Lysine deficiency impaired growth performance and immune response and aggravated inflammatory response of the skin, spleen and head kidney in grown-up grass carp (Ctenopharyngodon idella)

This dissertation was primarily focused on the immune response, inflammatory response and molecular mechanisms in the skin, head kidney and spleen of grown-up grass carp (Ctenopharyngodon idella). Six iso-nitrogen diets differing in lysine concentrations (5.6, 8.5, 11.6, 14.4, 17.5 and 20.7 g/kg) were fed to 540 grass carp (164.85 ± 0.79 g) for 60 d. After that, grass carp were challenged by Aeromonas hydrophila for 6 d. This study revealed that lysine deficiency (1) suppressed the growth performance of the fish and decreased their ability to resist skin lesion morbidity, (2) impaired the immune organ^'s immune response by decreasing the gene expressions of mucin, liver-expressed antimicrobial peptide (LEAP)-2B, β-defensin-1 and LEAP-2A and the production of antibacterial compounds of grown-up grass carp, and (3) aggravated the inflammatory response of immune organs in the fish by increasing the gene expressions of pro-inflammatory cytokines (interferon γ2 [IFN-γ2], tumor necrosis factor α [TNF-α], interleukin [IL]-15, IL-17D, IL-12p40, IL-6 and IL-8) and down-regulating anti-inflammatory cytokines (IL-11, transforming growth factor β1 [TGF-β1], IL-10 and IL-4/13A), which were tightly correlated with signal transducer and activator of transcription (STAT)1 and STAT3 signaling pathway, respectively. The different phenomenon in the skin, spleen and head kidney of fish may be correlated with the difference in gene subtype. In addition, using quadratic regression analysis of percent weight gain (PWG), skin lesion morbidity, and the lysozyme activities in the spleen and head kidney, the dietary lysine requirements for grown-up grass carp were estimated to be 13.58, 13.51, 14.56 and 14.18 g/kg, respectively.

Regulation of growth, intestinal microflora composition and expression of immune-related genes by dietary supplementation of Streptococcus faecalis in blunt snout bream (Megalobrama amblycephala)

A 10-week feeding trial was performed to investigate the effects of Streptococcus faecalis on the growth, intestinal microflora composition and expression of immune-related genes of blunt snout bream (Megalobrama amblycephala). Fish (46.32 ± 0.09 g) were fed four experimental diets containing 0 cfu/g (SF0, control), 1 × 10⁵ cfu/g (SF1), 1 × 10⁶ cfu/g (SF2) and 1 × 10⁷ cfu/g (SF3) of S. faecalis, respectively. Results showed that daily growth index (DGI), feed efficiency ratio (FER), plasma glucose level, plasma contents of total protein and albumin as well as intestinal serous layer (SL), muscular layer (ML), submucous layer (SML), villi thickness (VT) and lamina propria (LP) were all no significant difference among all the treatments, whereas their (except plasma albumin content and intestinal ML) relatively high values were found in the SF2 group. Meanwhile, the intake of the SF2 diets significantly increased plasma globulin content and intestinal digestive enzymes activities, the opposite was true for the activities of plasma aspartate aminotransferase (AST) and alanine transaminase (ALT). In addition, the analysis of the intestinal microbiota showed that fish fed the SF2 diet have the highest values of intestinal alpha diversity and intestinal abundances of Actinobacteria, Chlamydiae, Firmicutes, Planctomycetes, Verrucomicrobia, Clostridium and Synechococcus, while the opposite was true for intestinal abundances of Acinetobacter, Anoxybacillus, Flavobacterium, Planctomyces, Plesiomonas, Pseudomonas, Staphylococcus and Clostridium perfringens. At the molecular level, the expression levels of tumour necrosis factor α (TNF α), interleukin 1β (IL 1β) and heat shock proteins 7 (HSP 70) in head kidney and spleen were all decreased significantly with the increasing S. faecalis levels up to 1 × 10⁶ cfu/g, and then they were increased with further increasing S. faecalis levels. Overall, dietary supplementation of S. faecalis at 1 × 10⁶ cfu/g could improve the intestinal health and innate immunity of blunt snout bream.