Search Results (1,836)

Amino acid availability is central for the synthesis of macromolecules and numerous bioactive compounds. Amino acids are also involved in ATP production, cell signaling, and the epigenetic regulation of gene expression in human cells. From clinical and experimental studies, it appears that supplementation with specific amino acids may be relevant to correct for amino acid deficiency in the case of insufficient supply from dietary proteins with regards to the amounts needed for optimal metabolism and physiological functions. Clinical and experimental arguments suggest that amino acid supplementation may be indicated in specific situations under a specific nutritional context. However, it is essential not to overdose with excessive quantities of amino acids in supplements beyond the upper levels of safe intake (ULSI). In this narrative review, I recapitulate the protein and amino acid requirements for the general population and for subgroups of the population, and these requirements are compared to the usual consumption. Typical examples of clinical trials showing the benefits from amino acid supplementation in different physiological and pathophysiological contexts are presented together with results obtained from experimental studies. Parameters such as the no-observed-adverse-effect-level (NOAEL) values used to determine the ULSI for amino acid supplementation are defined, and values determined in clinical trials are given and discussed. Finally, prospects for future research in the field are proposed. Full article

Several studies have demonstrated that methionine supplementation in fish diets enhances immune status, inflammatory response, and resistance to bacterial infections by modulating for DNA methylation, aminopropylation, and transsulfuration pathways. However, the immunomodulatory effects of methionine in viral infections remain unexplored. This study aimed to evaluate the effect of methionine supplementation on immune modulation and resistance to the viral haemorrhagic septicaemia virus (VHSV) in rainbow trout (Oncorhynchus mykiss). Two diets were formulated and fed to juvenile rainbow trout for four weeks: a control diet (CTRL) with all nutritional requirements, including the amino acid profile required for the species, and a methionine-supplemented diet (MET), containing twice the normal requirement of DL-methionine. After feeding, fish were bath-infected with VHSV, while control fish were exposed to a virus-free bath. Samples were collected at 0 (after feeding trial), 24, 72, and 120 h post-infection for the haematological profile, humoral immune response, oxidative stress, viral load, RNAseq, and gene expression analysis. In both diets, results showed a peak in viral activity at 72 h, followed by a reduction in viral load at 120 h, indicating immune recovery. During the peak of infection, leukocytes, thrombocytes, and monocytes migrated to the infection site, while oxidative stress biomarkers (superoxide dismutase glutathione S-transferase, and glutathione redox ratio) suggested a compromised ability to manage cellular imbalance due to intense viral activity. At 120 h, immune recovery and homeostasis were observed due to an increase in the amount of nitric oxide, GSH/GSSG levels, leukocyte replacement, monocyte influx, and a reduction in the viral load. When focusing on the infection peak, gene ontology (GO) analysis showed several exclusively enriched pathways in the skin and gills of MET-fed fish, driven by the upregulation of several key genes. Genes involved in recognition/signalling, inflammatory response, and other genes with direct antiviral activity, such as TLR3, MYD88, TRAF2, NF-κB, STING, IRF3, -7, VIG1, caspases, cathepsins, and TNF, were observed. Notably, VIG1 (viperin), a key antiviral protein, was significantly upregulated in gills, confirming the modulatory role of methionine in inducing its transcription. Viperin, which harbours an S-adenosyl-L-methionine (SAM) radical domain, is directly related to methionine biosynthesis and plays a critical role in the innate immune response to VHSV infection in rainbow trout. In summary, this study suggests that dietary methionine supplementation can enhance a more robust fish immune response to viral infections, with viperin as a crucial mediator. The improved antiviral readiness observed in MET-fed fish underscores the potential of targeted nutritional adjustments to sustain fish health and welfare in aquaculture. Full article

The growing demand for sustainable protein sources has increased interest in algae and aquatic plants as alternatives to animal-derived proteins. These resources are rich in protein, amino acids, and umami compounds but require suitable extraction methods to maximize yield and quality. This study compared three green extraction techniques—maceration (MAE, 80 °C, 2 h), ultrasound-assisted extraction (UAE, 750 W, 20 kHz, 50% amplitude, 35 °C, pH 12, 1 h), and enzyme-assisted extraction (EAE, 5% β-glucanase/flavourzyme, 55 °C, pH 6.5, 1 h)—on five raw materials: wakame (commercial seaweed), hair seaweed, sea lettuce, water silk algae, and Wolffia. The result revealed that both raw materials and extraction methods significantly (p < 0.05) affected protein yield, amino acid, physicochemical properties, and taste detection with e-tongue. Wolffia extracted by MAE yielded the highest protein overall, followed by UAE and EAE methods, when compared with commercial seaweed. The relationship between amino acid profiles and taste detection was investigated by principal component analysis (PCA) and hierarchical cluster analysis (HCA); the samples with higher glutamic and aspartic acids were linked with umami taste, while histidine contributed to bitter taste. Overall, the findings highlighted that extraction efficiency was influenced more by the extraction method–material compatibility than the raw material alone. Full article

Determining protein requirements (PRs) for dogs remains a longstanding challenge. During growth, the rapid rate of protein deposition increases the demand for amino acids. In adult dogs, differences in overall diet digestibility and lower energy requirements of domestic dogs have led to discrepancies between the minimum crude protein (CP) value proposed by the National Research Council (NRC; 80 g of CP/kg of diet) and the 180 g of CP/kg of diet proposed by the European Pet Food Industry Federation (FEDIAF) and the Association of American Feed Control Officials (AAFCO), although most commercially available adult dog feeds offer protein levels that exceed both recommendations. In elderly dogs, physiological changes such as sarcopenia and reduced energy intake indicate a potential increase in PR, although evidence remains scarce. A similar gap exists for pregnant and lactating bitches, since most recommendations rely on extrapolations from growth studies. Classical PR recommendations were based on body weight gain and nitrogen balance (NB), methods that present important limitations. Due to this, stable isotope methods—including ¹³C-leucine, ¹⁵N-glycine, and ¹³C-phenylalanine—have emerged as precise methodological tools, enabling a detailed and dynamic assessment of whole-body protein metabolism, protein quality, and more accurate determination of PR and recommended allowance across different life stages. Full article

Background: Alzheimer’s disease (AD), a progressive brain disorder, is the most common form of dementia and necessitates the development of effective intervention strategies. Ginseng-Natto composite fermentation products (GN) have demonstrated beneficial bioactivities in mouse models of AD; however, the underlying mechanism of action through which GN ameliorates AD requires further elucidation. Methods: Mice received daily intragastric administration of low- or high-dose GN for 4 weeks, followed by intraperitoneal injection of scopolamine to induce the AD model. The pharmacological effects of GN were systematically evaluated using the Morris water maze test, ELISA, and H&E staining. To further investigate the underlying mechanisms, 16S rRNA gene sequencing and metabolomics were employed to analyze the regulatory effects of GN on the gut–brain axis. Additionally, Western blotting was performed to assess the impact of GN on blood–brain barrier (BBB) integrity. Results: GN intervention significantly ameliorated cognitive deficits and attenuated neuropathological injury in AD mice, restoring the brain levels of acetylcholine (ACh), acetylcholinesterase (AChE), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) to normal ranges. GN reshaped the gut microbiota by promoting beneficial bacteria and inhibiting pro-inflammatory strains. It also regulated key metabolic pathways related to amino acid and unsaturated fatty acid metabolism. This metabolic remodeling restored the compromised BBB integrity by upregulating tight junction proteins (ZO-1, Occludin and Claudin-1). Conclusions: Our findings demonstrate that GN ameliorates AD through a gut-to-brain pathway, mediated by reshaping the microbiota-metabolite axis and repairing the BBB. Thus, GN may represent a promising intervention candidate for AD. Full article

Background: The global dissemination of multidrug-resistant (MDR) Salmonella poses a persistent and serious threat to food safety systems. As a leading poultry-exporting country, Thailand requires a comprehensive understanding of how resistance plasmids spread among Salmonella populations within its chicken production chain. Methods: Between March 2023 and February 2024, 223 Salmonella isolates were collected from chicken slaughterhouses and markets in northeastern Thailand. From these, 19 representative MDR Salmonella enterica isolates, selected based on distinct spatiotemporal distributions, underwent whole-genome sequencing. Genomic analyses included sequence typing, core-genome phylogenetics, and screening for antimicrobial resistance genes. Plasmid replicons were identified, and functional annotation was performed using the COG database. Results: Phylogenetic analysis revealed 11 distinct sequence types within the population. Among these, ST1541 and ST50 showed clear evidence of clonal transmission across different production stages, with a notable clustering pattern observed during the winter season. All sequenced isolates exhibited an MDR phenotype. Plasmids were detected in 78.9% of isolates, with conjugative plasmids being the most frequent type (57.9%). The β-lactamase gene bla_TEM-60 was the most prevalent (78.9%) and showed a strong correlation (r ≥ 0.7) with resistance to both ampicillin and cefotaxime. Functional annotation further revealed an abundance of genes involved in carbohydrate and amino acid metabolism across all isolates. Conclusions: These findings indicate that MDR Salmonella dissemination is driven by two synergistic mechanisms: the clonal expansion of fit lineages and the horizontal transfer of conjugative plasmids harboring β-lactamase genes. We identified IncI-gamma-K1 and Col-related plasmids as key vectors in this process. This study advocates for targeted interventions, guided by a One Health approach, that specifically aim to disrupt plasmid transmission at critical control points, such as slaughterhouses, to curb the spread of antimicrobial resistance. Full article

The maximum protein or nitrogen deposition is commonly used as the basis for modeling the amino acid intake in growing birds. In previous studies, the exponential functions of the nitrogen balance data were used to estimate the theoretical maximum for nitrogen deposition (ND_maxT) as a reference model for the amino acid intake. However, this amino acid intake value is only valid for the period in which the ND_maxT was estimated. Additionally, physiological changes, such as the rapid development of reproductive organs and associated increases in protein deposition that occur in the period before the first egg is laid, should be considered in the models. Thus, this study was conducted to model the daily ND_maxT of pullets and integrate this value into the factorial model to estimate the daily methionine + cysteine (Met+Cys) intake. Our results showed that, up to 63 days of age, the values of ND_maxT obtained via the modeling procedure were 11% higher than the values predicted using the Gompertz function. At 105 days, there was a protein deposition peak from the growth of the reproductive organs, which contributed 14% of the variation in the model in this age. Alongside these factors, the integration of the models enabled daily Met+Cys estimates consistent with the literature; however, the recommendations varied according to the targeted daily protein deposition (50% or 60% of ND_maxT), daily feed intake, and amino acid utilization efficiency. The modeling approach demonstrated here for Met+Cys can be used to model other amino acid requirements and can be extended to other species. Full article

Levilactobacillus brevis is able to produce ɣ-aminobutyric acid (GABA), a non-proteogenic amino acid that provides several benefits to human health. In this study, we investigated the effect of glutamate (Glu) and oxygen (O₂) on biomass yield, GABA production and regulation of the gad operon in Lvb. brevis LB12. A change in incubation atmosphere from anaerobiosis (AN) to aerobiosis (AE) was applied to elucidate if AE pre-adaptation and cultivation could be exploited to improve cell density, as well as to determine the role of O₂ on the expression of the gad operon. AE increased biomass yield, but impaired Glu to GABA conversion, in both the cultivation and the adaptation phases. The gad operon (gadR, gadC, gadB, gltX) was up-regulated in the presence of Glu, while O₂ strongly reduced the transcription of gadC and gadB. Switching the incubation atmosphere (AE vs. AN) and Glu supplementation did not restore the gene functionality, suggesting that the negative effect of O₂ was persistent and more prolonged adaptation to AN would be required. This study provides additional data on the regulation of the gad operon, but further insight on the effect of O₂ upon GABA production by Lvb. brevis must be expanded to understand the possible mechanisms involved. Full article

Glucagon is a peptide hormone secreted by pancreatic alpha cells which elevates blood glucose and plays a critical role in diabetes onset and homeostasis. The accurate assessment of glucagon concentration is challenging due to its structural similarity with other hormones, causing cross-reactivity in antibody-based methods. Rapid and specific glucagon detection is essential, particularly during hypoglycemia. This study aimed to develop glucagon-specific probes combining high specificity, rapid detection, and ease of operation. We designed novel peptide-based probes by screening glucagon-binding peptides from the glucagon receptor sequence using a peptide array method. This strategy, based on receptor amino acid sequences, can be applied to the identification of binding peptides for other hormones, expanding its potential utility. The screened peptides were conjugated with fluorescent dyes to create probes enabling detection within 30 min. The developed probes demonstrated superior specificity for glucagon relative to similar sequence analogs compared with conventional antibody-based methods, with detection limits in the nanomolar range. This study represents a proof-of-concept approach for rapid and highly specific glucagon detection. However, further optimization of probe sensitivity and validation under physiological conditions will be required before clinical or diagnostic application. These improvements in the probe’s properties will enable the reliable blood glucagon detection and accurate diagnostic assessment of diabetes-related diseases. Full article

Amaranth 11S globulin is a plant protein that is renowned for its high essential amino acid content and nutritional value. It has undergone modification through the insertion of antihypertensive peptides valine-tyrosine (VY), which act as angiotensin-converting enzyme (ACE) inhibitors. The expression of this protein was carried out in E. coli. Despite the potential of this protein, an efficient purification method is still required to allow its evaluation and subsequent application. This work proposes a procedure that allows for high purification and yield. After obtaining the purified proteins from the inclusion bodies and purifying them in an insoluble form, it was determined that this process did not affect their bioactivity. Full article

The amino acid cysteine is essential to Campylobacter jejuni survival, providing the bacterial cells with the element sulfur. When cysteine is not available for uptake, C. jejuni can synthesize cysteine from serine and sulfide or thiosulfate. The cysM gene produces a cysteine synthase protein required for this process. Transcriptional control for cysM has been shown to reside within an untranslated sequence directly upstream of the gene. The untranslated sequence contains a conserved single-nucleotide polymorphism that was previously shown to influence gene transcription. Identification of the 5′ end of the cysM mRNA transcript confirmed that the SNP is present within full-length gene transcripts. A new sulfur starvation medium was deployed to study the survival and cysM transcription of C. jejuni strains with different SNP forms in the presence or absence of sulfide. Differences in survival between the SNP forms were observed during supplementation with low concentrations of sulfide. Additionally, differences in the cysM transcription profiles between the same strains with different SNP forms were observed when supplemented with a range of sulfide concentrations. The results support the hypothesis that a gene regulatory element is localized to the area around the SNP in the untranslated region upstream of cysM. Full article

Native to the western Atlantic, the Atlantic blue crab Callinectes sapidus (CS) has spread to the Mediterranean, affecting local ecosystems and mussel aquaculture and leading to severe ecological and financial losses in Italy and other areas. Given its rapid spread and socio-economic impacts, several countries have begun to exploit CS commercially, but the consumers’ interest is still limited. In this study, we analysed both nutrient and nutraceutical profiles of CS meats, evaluating potential differences related to sex and meat typology. We found that CS meats are rich in high quality proteins and contain all the essential amino acids required for a correct diet. The fat of CS is not only rich in polyunsaturated fatty acids (PUFAs) but also displays remarkably low atherogenicity and thrombogenicity indices, highlighting its strong potential in promoting cardiovascular health. In addition, CS is rich in nutraceutical compounds, in particular polyphenols and astaxanthin, revealing a good antioxidant activity maintained after simulated gastrointestinal hydrolysis. Last but not least, CS has remarkable α-glucosidase and angiotensin-converting enzyme inhibitory activity, highlighting potential benefits in controlling glycaemic peaks and hypertension. Full article

Metabolomics research in schizophrenia has revealed consistent alterations across multiple biochemical domains, including energy metabolism, lipid composition, amino acid pathways, and oxidative stress regulation. The most reproducible findings include the dysregulation of the tryptophan–kynurenine pathway, disturbances in arginine/nitric oxide metabolism, alterations in phospholipid and sphingolipid profiles, reduced glutathione (GSH) in the brain, and elevated lactate levels, suggesting mitochondrial dysfunction. Antipsychotic treatment itself modifies a wide range of metabolites, complicating biomarker discovery. Although no single biomarker has yet achieved clinical utility, systematic reviews and Mendelian randomization studies provide evidence for validated biomarker panels and potential causal links between peripheral metabolite signatures and schizophrenia risk. The aim of this study is to characterize metabolic changes in patients diagnosed with schizophrenia, where each group received different non-invasive therapeutic methods and was compared to patients continuing standard pharmacotherapy without modification. The study results show that schizophrenia is associated with systemic metabolic disturbances affecting energy, amino acid, lipid, and redox pathways. Further development of research in this area requires comprehensive and long-term studies integrated with modern imaging and analytical techniques. Full article

Seaweeds are emerging renewable biomass resources rich in valuable phytochemicals; however, effective stabilization strategies are required to enable their incorporation into sustainable food and bioprocessing applications. This study investigated the effects of convective drying (40–80 °C) and freeze-drying on the chemical composition and functional properties of the underexplored red seaweed Sarcodiotheca gaudichaudii. The drying method significantly modulated nutrient retention, pigment stability, and bioactivity. Freeze-drying and high-temperature convective drying (≥70 °C) resulted in higher protein and saturated fatty acid contents but led to substantial losses of pigments and antioxidant capacity. In contrast, moderate convective drying (40–60 °C) favored the retention of minerals, polyunsaturated fatty acids, essential amino acids, and pigments, while enhancing total phenolic and flavonoid contents and improving antioxidant performance (DPPH and ORAC). All extracts exhibited dose-dependent α-glucosidase inhibition (25–58%) within a concentration range of 0.10–40.0 mg/mL, with freeze-dried samples showing the strongest inhibitory effect. Similarly, cytotoxicity assays conducted on A549 and AGS cancer cell lines at concentrations of 1.25–40.0 mg/mL revealed that freeze-dried extracts consistently displayed the lowest IC₅₀ values. Overall, convective drying better preserved nutritional quality, whereas freeze-drying maintained higher biological functionality, revealing a process-dependent trade-off relevant to industrial biomass stabilization and functional ingredient development. Full article

Invertebrate iridescent viruses (IIVs, family Iridoviridae) are icosahedral double-stranded DNA viruses that infect a wide range of invertebrates, particularly in humid and aquatic environments. During field trials in Chiapas, southern Mexico, larvae of the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), displayed an unexpected lavender iridescence, leading to the discovery of novel IIV isolates from this major agricultural pest. Restriction endonuclease analysis revealed evident diversity among isolates from individual infected larvae. Although one field experiment yielded inconclusive results, a second experiment revealed a positive association between IIV disease and SfMNPV infection, compared to a negative association with the prevalence of parasitoids, and no association with entomopathogenic nematodes (probably Hexamermis sp.). These findings require further investigation to determine the distinct ecological routes through which the virus may transmit across host species. IIV infection of S. frugiperda was also identified in Veracruz State, Mexico, and northern Argentina, revealing a previously unrecognized geographic and host range for these viruses. The genomic and evolutionary features of the three isolates from S. frugiperda were compared with those of two other lepidopteran isolates from Helicoverpa zea (IIV30C obtained from CSIRO) and Anticarsia gemmatalis (AgIIV). Genome sizes ranged between 196.1 and 205.4 kbp (~28% GC content), with several large inversions, and were rich in tandem repeats. The average amino acid identity of the complete genomes and phylogenetic analyses of 26 core gene sequences placed all five isolates within the genus Chloriridovirus, closely related to IIV22 and IV22a isolated from blackflies (Diptera) in Wales and a previously sequenced isolate of IIV30 from the USA. We conclude that these lepidopterans are all infected by closely related strains of the virus species Chloriridovirus simulium1 across their native geographical range. These findings highlight the unexpected ecological breadth and evolutionary adaptability of IIVs. Full article