Arginine Levels Research Articles

Proteobacteria impair anti-tumor immunity in the omentum by consuming arginine

Gut microbiota influence anti-tumor immunity, often by producing immune-modulating metabolites. However, microbes consume a variety of metabolites that may also impact host immune responses. We show that tumors grow unchecked in the omenta of microbe-replete mice due to immunosuppressive Tregs. By contrast, omental tumors in germ-free, neomycin-treated mice or mice colonized with altered Schaedler's flora (ASF) are spontaneously eliminated by CD8+ Tcells. These mice lack Proteobacteria capable of arginine catabolism, causing increases in serum arginine that activate the mammalian target of the rapamycin (mTOR) pathway in Tregs to reduce their suppressive capacity. Transfer of the Proteobacteria, Escherichia coli (E.coli), but not a mutant unable to catabolize arginine, to ASF mice reduces arginine levels, restores Treg suppression, and prevents tumor clearance. Supplementary arginine similarly decreases Treg suppressive capacity, increases CD8+ Tcell effectiveness, and reduces tumor burden. Thus, microbial consumption of arginine alters anti-tumor immunity, offering potential therapeutic strategies for tumors in visceral adipose tissue.

Changes in Plasma Free Amino Acid Profile in Endurance Athletes over a 9-Month Training Cycle.

We aimed to evaluate long-term changes in proteinogenic and non-proteinogenic plasma free amino acids (PFAA). Eleven male endurance triathletes participated in a 9-month study. Blood was collected at rest, immediately after exhaustive exercise, and during 30-min recovery, in four consecutive training phases: transition, general, specific, and competition. Twenty proteinogenic and 22 non-proteinogenic PFAAs were assayed using the LC-ESI-MS/MS technique. The structured training modified the patterns of exercise-induced PFAA response, with the competition phase being the most distinct from the others. Branched-chain amino acids (p = 0.002; η2 = 0.216), phenylalanine (p = 0.015; η2 = 0.153), methionine (p = 0.002; η2 = 0.206), and lysine (p = 0.006; η2 = 0.196) declined more rapidly between rest and exhaustion in the competition phase. Glutamine (p = 0.008; η2 = 0.255), glutamate (p = 0.006; η2 = 0.265), tyrosine (p = 0.001; η2 = 0.195), cystine (p = 0.042; η2 = 0.183), and serine (p < 0.001; η2 = 0.346) levels were reduced in the competition phase. Arginine (p = 0.046; η2 = 0.138) and aspartate (p = 0.011; η2 = 0.171) levels were highest during exercise in the transition phase. During the competition phase, α-aminoadipic acid (p = 0.023; η2 = 0.145), β-aminoisobutyric acid (p = 0.007; η2 = 0.167), β-alanine (p < 0.001; η2 = 0.473), and sarcosine (p = 0.017; η2 = 0.150) levels increased, whereas phosphoethanolamine (p = 0.037; η2 = 0.189) and taurine (p = 0.008; η2 = 0.251) concentrations decreased. Overtraining indicators were not elevated. The altered PFAA profile suggests adaptations within energy metabolic pathways such as the tricarboxylic acid cycle, oxidative phosphorylation, ammonia neutralization, the purine nucleotide cycle, and buffering of intracellular H+ ions. The changes seem to reflect normal adaptations.

Targeting RNA-binding motif protein 39 for arginine reduction: unveiling metabolic vulnerability in arginine-dependent liver cancer.

Cancer is increasingly acknowledged as a metabolic disease, characterized by metabolic reprogramming as its hallmark. However, the precise mechanisms behind this phenomenon and the factors contributing to tumorigenicity are still poorly understood. In a recent publication in Cell, Mossmann and colleague reported a study unveiling arginine as a molecule with second messenger-like properties that reshapes metabolism to facilitate the tumor development in hepatocellular carcinoma (HCC). Their research revealed that the RNA-binding motif protein 39 (RBM39)-mediated increase in asparagine synthesis results in increased arginine uptake. This establishes a positive feedback loop that sustains elevated levels of arginine and facilitates oncogenic metabolic reprogramming. Additionally, Mossmann etal. demonstrated that depleting RBM39 with indisulam effectively disrupts the proto-oncogenic metabolic reprogramming in HCC. This discovery presents a novel treatment strategy for arginine-dependent liver cancers.

Levels of asymmetric dimethylarginine in plasma and aqueous humor: a key risk factor for the severity of fibrovascular proliferation in proliferative diabetic retinopathy.

Proliferative diabetic retinopathy (PDR) is a common diabetes complication, significantly impacting vision and quality of life. Previous studies have suggested a potential link between arginine pathway metabolites and diabetic retinopathy (DR). Connective tissue growth factor (CTGF) plays a role in the occurrence and development of fibrovascular proliferation (FVP) in PDR patients. However, the relationship between arginine pathway metabolites and FVP in PDR remains undefined. This study aimed to explore the correlation between four arginine pathway metabolites (arginine, asymmetric dimethylarginine[ADMA], ornithine, and citrulline) and the severity of FVP in PDR patients. In this study, plasma and aqueous humor samples were respectively collected from 30 patients with age-related cataracts without diabetes mellitus (DM) and from 85 PDR patients. The PDR patients were categorized as mild-to-moderate or severe based on the severity of fundal FVP. The study used Kruskal-Wallis test to compare arginine, ADMA, ornithine, and citrulline levels across three groups. Binary logistic regression identified risk factors for severe PDR. Spearman correlation analysis assessed associations between plasma and aqueous humor metabolite levels, and between ADMA and CTGF levels in aqueous humor among PDR patients. ADMA levels in the aqueous humor were significantly greater in patients with severe PDR than in those with mild-to-moderate PDR(P=0.0004). However, the plasma and aqueous humor levels of arginine, ornithine, and citrulline did not significantly differ between mild-to-moderate PDR patients and severe PDR patients (P>0.05). Binary logistic regression analysis indicated that the plasma (P=0.01) and aqueous humor (P=0.006) ADMA levels in PDR patients were risk factors for severe PDR. Furthermore, significant correlations were found between plasma and aqueous humor ADMA levels (r=0.263, P=0.015) and between aqueous humor ADMA and CTGF levels (r=0.837, P<0.001). Elevated ADMA levels in plasma and aqueous humor positively correlate with the severity of FVP in PDR, indicating ADMA as a risk factor for severe PDR.

Optimal level of dietary arginine enhances growth performance, haemato-biochemical status, metabolic responses and growth-related gene expression of GIFT juveniles reared in inland saline water

The effects of arginine levels in diets on growth performance, survival, and haemato-biochemical responses and gene expression of genetically improved farmed tilapia (GIFT) juveniles raised in inland saline water (ISW) of 10 ppt were evaluated through a 60-day growth trial. Seven isoproteinaceous (⁓320 g protein/kg), isolipidic (80 g/kg) and isoenergetic (16.8 MJ DE/kg) diets with graded levels of arginine viz. A10 (10 g/kg), A12.5 (12.5 g/kg), A15 (15.0 g/kg), A17.5 (17.5 g/kg), A20 (20.0 g/kg), A22.5 (22.5 g/kg) and A25 (25.0 g/kg) were prepared. Acclimated GIFT juveniles (3.75 ± 0.017 g) were randomly assigned into seven treatments in triplicate with 15 fish/replicate and fed with respective diets thrice a day on a satiation basis. The percent weight gain, specific growth rate, protein efficiency ratio, whole carcass protein, tissue alanine and aspartic acid aminotransferase activities, serum total protein, albumin and globulin concentration and expression of IGF-1 & IGF-1R genes of fish significantly increased, while feed conversion ratio significantly decreased with increasing arginine in the diet up to 17.5 g/kg and decreased thereafter. Additionally, white blood cell count increased with rising arginine levels in the diet. However, body indices, survival, whole carcass lipid, total ash and essential amino acids contents, activities of digestive and antioxidant enzymes, serum glucose level and blood haemoglobin level and red blood cell count of fish remained unchanged for different treatments. Based on broken-line regression and second order polynomial regression models in relation to hepatic IGF-1 gene expression and percent weight gain, the dietary optimal arginine level was found to be 15.97 and 16.76 g/kg and 17.06 and 17.41 g/kg, respectively with the optimum range of 15.97 to 17.41 g/kg for successful culture of GIFT in ISW of 10 ppt salinity.

Elevated Plasma Levels of Arginines During Labor Among Women with Spontaneous Preterm Birth: A Prospective Cohort Study.

Preterm birth (PTB) is a leading cause of infant mortality and morbidity. The pathogenesis of PTB is complex and involves many factors, including socioeconomy, inflammation and infection. Asymmetric dimethylarginine, ADMA and symmetric dimethylarginine, SDMA are involved in labor as inhibitors of nitric oxide, a known relaxant of the uterine smooth muscles. Arginines are scarcely studied in relation to PTB and we aimed to investigate arginines (ADMA, SDMA and L-arginine) in women with spontaneous PTB and term birth. The study was based on data from the population-based, prospective cohort BASIC study conducted in Uppsala County, Sweden, between September 2009 and November 2018. Arginines were analyzed by Ultra-High Performance Liquid Chromatography using plasma samples taken at the onset of labor from women with spontaneous PTB (n = 34) and term birth (n = 45). We also analyzed the inflammation markers CRP, TNF-R1 and TNF-R2 and GDF-15. Women with spontaneous PTB had higher plasma levels of ADMA (p<0.001), and L-Arginine (p = 0.03). In addition, inflammation marker, TNF-R1 (p = 0.01) was higher in spontaneous PTB compared to term birth. Further, in spontaneous PTB, no significant correlations could be observed when comparing levels of arginines with inflammation markers, except ADMA versus CRP. These findings provide novel evidence for the potential involvement of arginines in the pathogenesis of spontaneous PTB and it seems that arginine levels at labor vary independently of several inflammatory markers. Further research is warranted to investigate the potential of arginines as therapeutic targets in the prevention and management of spontaneous PTB.

Arginine impacts aggregation, biofilm formation, and antibiotic susceptibility in Enterococcus faecalis.

Enterococcus faecalis is a commensal bacterium in the gastrointestinal tract (GIT) of humans and other organisms. E. faecalis also causes infections in root canals, wounds, the urinary tract, and on heart valves. E. faecalis metabolizes arginine through the arginine deiminase (ADI) pathway, which converts arginine to ornithine and releases ATP, ammonia, and CO 2 . E. faecalis arginine metabolism also affects virulence of other pathogens during co-culture. E. faecalis may encounter elevated levels of arginine in the GIT or the oral cavity, where arginine is used as a dental therapeutic. Little is known about how E. faecalis responds to growth in arginine in the absence of other bacteria. To address this, we used RNAseq and additional assays to measure growth, gene expression, and biofilm formation in E. faecalis OG1RF grown in arginine. We demonstrate that arginine decreases E. faecalis biofilm production and causes widespread differential expression of genes related to metabolism, quorum sensing, and polysaccharide synthesis. Growth in arginine also increases aggregation of E. faecalis and promotes decreased susceptibility to the antibiotics ampicillin and ceftriaxone. This work provides a platform for understanding of how the presence of arginine in biological niches affects E. faecalis physiology and virulence of surrounding microbes.

#2194 Targeted metabolomics analysis identifies a specific metabolomic profile in patients with early chronic kidney disease

Abstract Background and Aims The complex interconnections between various metabolites and the kidney play a major role in the pathogenesis of chronic kidney disease (CKD). Hence, by the assessment of the relationship between metabolites and the kidney, more accurate biomarkers could be discovered to prevent and detect CKD at an early stage. The primary goal of this study was to find new serum and urine biomarkers for the diagnosis of early CKD by conducting a metabolomic profiling through targeted metabolomics of both blood and urine in patients with CKD. Method This cross-sectional study comprised 80 patients with CKD who were categorized into six subgroups (G1-G6) based on their eGFR according to the KDIGO Guidelines. Additionally, 20 healthy individuals were included as healthy control participants (group C). Ultra-high-performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight-mass spectrometry was used to perform serum and urine metabolomic profiling. The 6 metabolites evaluated by this study were selected based on the results of a previous untargeted analysis research. Both blood and urine samples underwent multivariate analysis, which was subsequently followed by univariate analysis and quantitative analysis. Initially, the PLSDA score plot and VIP score were utilized. The application of the cross-validation procedure to the initial set of 6 molecules provided outstanding results, including high accuracy, high R² values, and a significant Q2 value. Hence, the model might be deemed as predictive. Random Forest analysis was utilized to conduct biomarker analysis and prediction. The specificity and sensitivity of the compounds identified as possible biomarkers were assessed using the Receiver Operating Characteristic (ROC) curve and the area under the curve (AUC). Results There were strong positive correlations between eGFR and serum levels of Arginine (p &amp;lt; 0.05) and L-Acetylcarnitine (p &amp;lt; 0.05). Of note, the amounts of L-Methionine, L-Phenylalanine, Kynurenic acid, and Indoxyl sulfate in serum showed a progressive increase from group C to subgroups G1-G5. Furthermore, L-Methionine, L-Phenylalanine, Kynurenic acid, and Indoxyl sulfate exhibited a negative correlation with eGFR (p &amp;lt; 0.05). In addition, there was a positive correlation between the levels of urine Arginine, L-Methionine, and L-Phenylalanine and eGFR (p &amp;lt; 0.05). Urine levels of Kynurenic acid, Indoxyl sulfate, and L-Acetylcarnitine were higher in groups G4 and G5, as compared to groups G1-G3b and C, respectively. The urinary concentrations of Indoxyl sulfate, Kynurenic acid, Indoxyl sulfate, and L-Acetylcarnitine exhibited a negative correlation with eGFR (p &amp;lt; 0.05). Conclusion The current study shows that serum and urinary metabolites levels in patients with CKD display an alteration in production, secretion, and excretion in all CKD stages. There was demonstrated a distinct metabolomic profile in the course of CKD which points to novel biomarkers useful for the diagnosis and progression evaluation of CKD from its early stages.

A panel of four plasma amino acids is a promising biomarker for newly diagnosed bladder cancer

BackgroundMetastasis and recurrence are the main causes of death in post-operative bladder cancer (BC), emphasizing the importance of exploring early-stage diagnostic markers. Serum biomarkers constitute a promising diagnostic approach for asymptomatic stage cancer as they are non-invasive, have high accuracy and low cost. AimsTo correlate concentrations of plasma amino acids with BC progression to assess their utility as an early-stage diagnostic. MethodsNewly diagnosed BC patients (n=95) and normal controls (n=96) were recruited during the period from 1 December 2018 to 30 December 2020. General and food frequency questionnaires established their basic information and dietary intake data. Venous blood samples were collected from fasting subjects and used to detect levels of plasma amino acids by liquid chromatography-mass spectrometry. Verification was performed on the GSE13507 transcriptome gene expression matrix of BC from Gene Expression Omnibus (GEO) database. ResultsEleven amino acids have been identified as altered in the plasma of newly diagnosed BC patients compared to controls (P < 0.05). Adjusted by gender, education, smoking and other factors, plasma ornithine level (OR = 0.256, 95% CI: 0.104 ∼ 0.630) is a protective factor for BC, plasma levels of methionine (OR = 3.460, 95% CI: 1.384 ∼ 8.651), arginine (OR = 3.851, 95% CI: 1.542 ∼ 9.616), and glutamate (OR = 3.813, 95% CI: 1.543 ∼ 9.419) are all risk factors for BC. ROC analysis demonstrated that the combination of plasma ornithine, methionine, arginine and glutamate could accurately diagnose BC (AUC = 0.84, 95% CI: 0.747 ∼ 0.833). In addition, the mRNA level of arginase 1 was decreased (P < 0.05), while the inducible nitric oxide synthase was increased significantly, which may be linked with the disturbance of arginine metabolism in BC patients. Further analysis of GEO database confirmed the role of arginine metabolism. ConclusionA biomarker panel containing four amino acids may provide a feasible strategy for the early diagnosis of BC. However, further validation is required through prospective studies.

90 Evaluating water- and feed-based arginine supplementation on newly weaned pig growth and gastrointestinal health

Abstract The objective of this experiment was to assess the influence of arginine (Arg) supplementation in water and/or feed on the growth performance and gastrointestinal health of newly weaned pigs. Pigs (n = 240; PIC 337 Χ 1050, Genus, Henderson, TN) were randomly allocated into 80 mixed-sex test pens and subjected to a 2 Χ 4 factorial design, with two levels of Arg supplementation in water (0% or 8% stock, dosed through a 1:128 proportioner) for the first phase (d 0-7), and four dietary arginine levels (0.85, 0.95, 1.05, and 1.15 standardized ileal digestible (SID) Arg to Lysine (Lys) ratios for the first two phases (d 0-7 and 7-21). All treatments were provided a common diet (0.96 SID Arg:Lys) for the last phase d 21- 42. One pig per pen underwent a dual sugar absorption test of lactulose at 500 mg/kg and mannitol at 50 mg/kg of body weight (BW) via gastric tube on d 7 and 21, with blood plasma collected 4 h post-administration. The pig tested on d 7 was subsequently euthanized for intestinal tissue collection. Pen growth performance and feed disappearance were evaluated for 3 phases; d 0-7, 7-21, and 21-42. The statistical analysis utilized generalized linear mixed model methods (SAS 9.4, Cary, NC) with the main effects of SID Arg:Lys in the feed and Arg level within the water, and the interaction between the two. Pen was the experimental unit. Orthogonal contrasts were tested for the linear and quadratic effects of the diet. Growth performance during the 1st period exhibited variability, reflected by negative gain to feed ratio (G:F), caused by health challenges of Rotavirus A. Consequently, data were analyzed separately for each phase. Increasing dietary SID Arg:Lys caused a significant linear effect (improvement; P = 0.04) on final BW (18.47 and 21.90 kg, for 0.85 and 1.15 SID Arg:Lys, respectively). However, discernible differences between dietary treatments were not observed (P &amp;gt; 0.1). Similarly, a trend (P = 0.09) suggested a linear impact of dietary SID Arg:Lys on average daily gain during the third phase (d 21-42). In terms of intestinal absorption and morphology, Arg supplementation, whether through water or diet, had no effect on lactulose and mannitol absorption on both d 7 and d 21, nor did it impact villous height, crypt depth, or the villi:crypt ratio in ileum tissues collected on d 7 post-weaning. In conclusion, dietary supplementation with Arg increased final BW but had no clear impacts on intestinal health within the variables measured, potentially impacted by the rotavirus diagnosis in the first week post wean.

Unveiling the roles of dietary Tryptophan and Arginine metabolism in Lactobacillus rhamnosus GG-mediated barrier protection

Inflammatory bowel disease (IBD) is often characterized by increased intestinal paracellular permeability and abnormalities in tight junctions (TJ). IBD patients commonly exhibit reduced serum tryptophan (TRP) levels. Furthermore, animal models on low-TRP diets are more susceptible to chemically induced intestinal inflammation, while those on high-TRP diets show reduced inflammation. The interaction between TRP and gut microbiota in reinforcing the intestinal barrier warrants further investigation. To address this, we introduced Lactobacillus rhamnosus GG (LGG), known for enhancing the gut barrier, and PBS as a control into germ-free mice fed TRP-suffcient or -deficient diets. Our analysis of the mouse ileal transcriptome revealed dramatic upregulation of key genes in arginine metabolism only in LGG-TRP mice, particularly of argininosuccinate lyase ( Asl) that catabolizes argininosuccinate (ASA). Interestingly, our in-silico analysis of human IBD data GEO 179285 transcriptome showed marked dysregulation of similar genes, including inappropriate increases in ASA synthetase ( Ass1). Moreover, this unique expression pattern in the mouse ileum was TRP-dependent and specific to LGG, and not observed in mice monocolonized with pathobiont Ruminococcus gnavus or specific pathogen-free mice. LC-MS analysis of fecal and serum metabolites in LGG-TRP mice revealed elevated levels of fecal arginine, glutamine, and aspartate, suggesting their involvement in host arginine biosynthesis, along with significant reductions in serum ASA levels. ASA was highly negatively correlated with numerous TJ genes, suggesting its potential to compromise barrier function. Indeed, treating mouse enteroids with ASA enhanced dextran permeability, exacerbated LPS disruption of the gut barrier, and decreased expression of TJ genes Ocln and Tjp1. Furthermore, elevated serum ASA and decreased colonic ASL levels were observed in colitis-afflicted mice, perturbing gut homeostasis, as indicated by increased fecal lipocalin-2 and delayed colitis recovery after intraperitoneal ASA administration. We propose that LGG-TRP stimulates gut-mediated ASA turnover as evidenced by substantial increases in Asl levels. Interestingly, LGG alone reduced ASA concentration in the culture medium under anaerobic and aerobic conditions. Collectively, our study identifies ASA as a potential biomarker of gut inflammation and enhanced permeability. Moreover, we highlight the potential of LGG-TRP therapy for IBD-associated leaky gut conditions, offering novel insights for gut health interventions. NIHR01-AT010243 (NG,RF), R01DK119198 (NG), NSF 1754783 (RF). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of Miscellaneous Meals Replacing Soybean Meal in Feed on Growth Performance, Serum Biochemical Parameters, and Microbiota Composition of 25-50 kg Growing Pigs.

The present study aims to determine the effect of miscellaneous meals (rapeseed meal, cottonseed meal, and sunflower meal) replacing soybean meal in feed on growth performance, apparent digestibility of nutrients, serum biochemical parameters, serum free amino acid content, microbiota composition and SCFAs content in growing pigs (25-50 kg). A total of 72 (Duroc × Landrace × Yorkshire) growing pigs with initial weights of 25.79 ± 0.23 kg were randomly divided into three treatments. The pigs were fed corn-soybean meal (CON), corn-soybean-miscellaneous meals (CSM), and corn-miscellaneous meals (CMM). Each treatment included six replicates with four pigs per pen (n = 24, 12 barrows and 12 gilts). Soybean meal accounted for 22.10% of the basal diet in the CON group. In the CSM group, miscellaneous meals partially replaced soybean meal with a mixture of 4.50% rapeseed meal, 3.98% cottonseed meal, and 4.50% sunflower meal. In the CMM group, miscellaneous meals entirely replaced soybean meal with a mixture of 8.50% rapeseed meal, 8.62% cottonseed meal, and 8.5% sunflower. The results showed that compared with the CON, the CSM and CMM groups significantly improved the average daily gain (ADG) of growing pigs during the 25-50 kg stage (p < 0.05) but had no effects on average daily feed intake (ADFI) and average daily feed intake/average daily gain (F/G) (p > 0.05). Moreover, the CMM group significantly reduced nutrient apparent digestibility of gross energy compared with the CON group. The serum biochemical parameters results showed that the CSM group significantly improved the contents of total protein (TP) compared with the CON group (p < 0.05). The CMM group significantly improved the contents of total protein (TP), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) compared with the CON group in serum (p < 0.05). In comparison with the CON group, the CMM group also significantly improved lysine (Lys), threonine (Thr), valine (Val), isoleucine (Ile), leucine (Leu), phenylalanine (Phe), arginine (Arg), and citrulline (Cit) levels in serum (p < 0.05). However, the CMM group significantly decreased non-essential amino acid content glycine (Gly) in serum compared with CON (p < 0.05), while compared with the CON group, the CSM and CMM groups had no significant effects on the relative abundance, the alpha-diversity, or the beta-diversity of fecal microbiota. Moreover, compared with the CON group, the CSM group significantly increased butyric acid and valeric acid contents of short-chain fatty acids (SCFAs) in feces (p < 0.05). In contrast to the CON group, the CMM group significantly reduced the contents of SCFAs in feces, including acetic acid, propionic acid, and isobutyric acid (p < 0.05). Collectively, the results of the present study indicate that miscellaneous meals (rapeseed meal, cottonseed meal, and sunflower meal) can partially replace the soybean meal and significantly improve the growth performance of growing pigs during the 25-50 kg stage. Thus, miscellaneous meals are a suitable protein source as basal diets to replace soybean meals for 25-50 kg growing pigs. These results can be helpful to further develop miscellaneous meals as a functional alternative feed ingredient to soybean meal.

Plasma Free Amino Acid and Carnitine Levels in Pregnant Women with Hydatidiform Mole: A Case-Controlled Study

Background: To determine plasma free amino acid (FAA) and carnitine levels in pregnant women with hydatidiform mole (HM). Materials and Methods: Twenty-three pregnant women with HM, and 24 healthy pregnant wo-men as controls were enrolled in the study. FAA and carnitine concentrations were measured in plasma using liquid chromatography/tandem mass spectrometry (LC-MS). Results: The levels of alanine, arginine, and valine from the 14 amino acids examined were signif-icantly lower in the HM group than in the healthy group (p = 0.019, p = 0.009, and p = 0.03, respec-tively). In addition, several carnitines, C8DC, C16:1, and C18, of the 27 carnitines examined were significantly higher in the HM group than in the control group (p = 0.021, p = 0.03, and p = 0.021, respectively). Conclusions: This study demonstrated that a decrease in some plasma FAAs and an increase in some plasma carnitine levels might be effective in the pathogenesis of HM.

Physiological and metabolic analyses reveal the proline-mediated flowering delay mechanism in Prunus persica.

Peaches are susceptible to various environmental stresses. Particularly in late spring, freezing temperatures can damage peaches and consequently, affect their productivity. Therefore, flowering delay is a prominent strategy for avoiding spring frost damage. Our previous study confirmed that treatment with 5% sodium alginate and 100 mM CaCl2 (5AG) to avoid frost damage during the blooming stage delays flowering. To reveal the flowering delay mechanism of peaches, this study systematically analyzed the modification of amino acid profiles in control and 5AG-treated peach plants at different day intervals. Our findings indicate that arginine (Arg), glutamate (Glu), and proline (Pro) levels differed between the control and 5AG-treated peach shoots throughout the phenological development of flower buds. Furthermore, two amino acids (Arg and Glu) are involved in the Pro pathway. Thus, using a computational metabolomics method, Pro biosynthesis and its characteristics, gene ontology, gene synteny, cis-regulatory elements, and gene organizations were examined to decipher the involvement of Pro metabolism in peach flowering delay. In addition, qRT-PCR analysis revealed the transcriptional regulation of Pro-related and flowering-responsive genes and their role in flowering delay. Overall, this pilot study provides new insights into the role of Pro in the flowering delay mechanisms in Prunus persica through 5AG treatment.

Allantoate Amidohydrolase OsAAH is Essential for Preharvest Sprouting Resistance in Rice

Preharvest sprouting (PHS) is an undesirable trait that decreases yield and quality in rice production. Understanding the genes and regulatory mechanisms underlying PHS is of great significance for breeding PHS-resistant rice. In this study, we identified a mutant, preharvest sprouting 39 (phs39), that exhibited an obvious PHS phenotype in the field. MutMap+ analysis and transgenic experiments demonstrated that OsAAH, which encodes allantoate amidohydrolase, is the causal gene of phs39 and is essential for PHS resistance. OsAAH was highly expressed in roots and leaves at the heading stage and gradually increased and then weakly declined in the seed developmental stage. OsAAH protein was localized to the endoplasmic reticulum, with a function of hydrolyzing allantoate in vitro. Disruption of OsAAH increased the levels of ureides (allantoate and allantoin) and activated the tricarboxylic acid (TCA) cycle, and thus increased energy levels in developing seeds. Additionally, the disruption of OsAAH significantly increased asparagine, arginine, and lysine levels, decreased tryptophan levels, and decreased levels of indole-3-acetic acid (IAA) and abscisic acid (ABA). Our findings revealed that the OsAAH of ureide catabolism is involved in the regulation of rice PHS via energy and hormone metabolisms, which will help to facilitate the breeding of rice PHS-resistant varieties.

Quality of edible bird’s nest treated by keratinolytic enzymes-based cleaning solution

Edible bird's nest (EBN) is one of the luxury foods that is widely used as a healthy food due to its nutritional value and therapeutic benefits. The traditional EBN washing process causes a reduction in weight and nutrient content and an increase in pollutants due to the use of hydrogen peroxide. An exploratory observation method was used to examine the quality of EBN from Collocalia fuciphaga before and after washing using a washing solution based on keratinolytic enzymes. There are four stages of EBN cleaning i.e. cleaning by tap water, ethanol solution, enzyme solution at room temperature and 50oC and drying at 40oC for 42 hrs. A total of 60 EBN (unclean, n = 30) and clean, n = 30) were analyzed using the AOAC method. The mineral content of Ca, Fe, K and Mg using atomic absorption spectrophotometry (AAS) except that P was measured by spectrophotometer. A carbohydrate estimation kit was used to measure glycoprotein content and the amino acid content was determined using the HPLC method. Evaluation of the cleanliness was carried out using a scoring system by semi-trained panelists. The results obtained showed that the clean EBNs were slightly yellowish-white in color, and the cleanliness of EBN before and after cleaning increased from 2.35 to 3.84. Clean EBN protein content decreased by 7.2% while total amino acids decreased from 38.51% to 32.71%. Clean EBN contains eight essential amino acids of 17.93% with high levels of leucine, valine, arginine, and threonine (2.42-2.96%). EBN's clean ash content increased from 3.7% to 7.8%. Carbohydrate content and iron in clean EBN were 39.19±0.76% and 14.35 mg/100 g dry matter, respectively. The high levels of carbohydrates and iron appear to be good sources of glycoprotein to support health and have the potential as an alternative source of iron for people with anemia. The stepwise EBN washing method using tapwater, ethanol and a washing solution based on keratinolytic enzymes can be applied to reduce weight loss and improve the quality of EBN.

Dietary arginine regulates the growth performance, antioxidant capacity, and immune response in Culter alburnus.

Culter alburnus is sensitive to stressors. Arginine is a precursor of nitric oxide, which can effectively relieve the level of oxidative stress and improve the antioxidant and immune capacity of fish. The effect of different arginine levels on topmouth culter (Culter alburnus) fry development performance, liver antioxidant capacity, and immune parameters were investigated in this study. Five diets (1.96%, ARG1, control group; 2.28%, ARG2; 2.52%, ARG3; 2.81%, ARG4; 3.09%, ARG5) were used to feed fry (initial weight 0.31 ± 0.01g) for 8weeks. The data showed that the final weight (FW), weight gain rate (WGR), and specific growth rate (SGR) of the ARG3 and ARG4 groups were significantly improved, while the feed conversion ratio (FCR) reduced significantly. Compared with the ARG1 group, all groups remarkably reduced the crude ash content of the whole body. The activity of hepatic superoxide dismutase (SOD) and the content of hepatic glutathione (GSH) were significantly increased in the ARG3 and ARG4 groups, while the malondialdehyde (MDA) content was significantly decreased. Compared with the ARG1 group, arginine levels in ARG2, ARG3, and ARG4 groups up-regulated the expression levels of Nrf2, down-regulated the gene expression level of Keap1 in the liver. And the expression of Nrf2/Keap1 pathway downstream genes Mn-SOD and CAT was up-regulated in ARG2 and ARG3 groups. Furthermore, the expression levels of MyD88 and IL-1β were down-regulated, and the anti-inflammatory gene TGF-β expression levels were up-regulated in the ARG2, ARG3, and ARG4 groups. Additionally, compared to the ARG1 group, there was a significant increase in the relative expression levels of the C3 and C4 genes in the ARG4 group. In conclusion, 2.28-2.81% dietary arginine levels improved the growth performance, promoted antioxidant capacity, and enhance immune response. The optimal level of arginine was determined by the quadratic regression analysis of SGR and FCR to be 2.55% of diet (5.43% of dietary protein) and 2.53% of diet (5.38% of dietary protein), accordingly.

The osmoregulatory mechanism in response to hypoosmotic stress and the key role of ABCC1 in osmoregulation in the mud crab, Scylla paramamosain

Scylla paramamosain is an important mariculture animal. In the present study, we examined the physiological and biochemical characteristics of juvenile S. paramamosain under hypoosmotic stress and further verified the function of ABCC1, a key transport protein in gill tissue. The results showed that Na+/K+-ATPase, Ca2+-ATPase, and Na+/K+/2Cl- cotransporter in gill tissues increased first and then decreased. In addition, SOD and CAT activities also began to gradually increase, protecting gill tissues from oxidative damage. The hemolymph osmolarity decreased rapidly from 792 mOsm/kg to 560 mOsm/kg within 6 h, and then rose to 626.25 mOsm/kg at 48 h, and then remained stable. At the same time, Na+, Cl-, K+, and Ca2+ concentrations were decreased to varying degrees. There were significant changes in free amino acids such as aspartic acid, glutamic acid, and asparagine in hemolymph in response to acute salt depletion. By injection of ABCC1 inhibitor/activator, it was found that while ABCC1 transporter activity in the MK-571 group showed a decreasing trend at 9 h, Na+/K+ -ATPase activity began to increase and reached a peak at 48 h. Compared with the control group, the levels of aspartic acid, glutamic acid, asparagine, glycine, arginine, alanine, lysine, and proline in the MK-571 group showed significant differences at 6 h; Significant differences in glutamate, asparagine, arginine, alanine, lysine, and proline appeared at 12 h in the Thiethylperazine group. These results suggested that the dynamic changes of gill ion transport enzymes, antioxidant enzymes, inorganic ions, and free amino acids in hemolymph occurred in S. paramamosain under hypoosmotic stress, and the ABCC1 transporter played an important role in this regulatory process.

Effects of low protein diets on acid-base balance, electrolyte balance, intestinal structure, and amino acid transport in piglets.

Reducing the dietary crude protein (CP) could effectively reduce pressure on protein ingredient supplies. However, few data have been reported about the extent to which CP can be reduced and whether limiting the use of soybean meal leads to electrolyte imbalance. In this experiment, using the low protein (LP) diet [2% lower than NRC (2012)], seventy-two piglets (35 days old) were randomly divided into 2 groups with 6 replicates of 6 piglets each: CON group (CP = 18.5%) and LP group (CP = 16.5%), to investigate the effect of the LP diet on electrolyte balance, acid-base balance, intestinal structure and amino acid transport in piglets. The results revealed that the LP diet decreased the average daily gain and dietary CP digestibility, and damaged the villi structure of the small intestine. Compared with the CON diet, the potassium content decreased and the chlorine content increased in the LP diet, and similar trends were shown in piglet serum. The arterial pH, pCO2, HCO3 -, and base excess of piglets in the LP group were lower than those in the CON group, while pO2 was higher than those in the CON group. Interestingly, the LP diet significantly increased the lysine content in piglet serum and significantly decreased the levels of arginine, leucine, and glutamic acid. Furthermore, the LP diet significantly affected the expression of some amino acid transport vectors (B0AT1, EAAC1, and y+LAT1). In summary, these findings suggested that the LP diet leads to acid-base imbalance, amino acid transport disorder and amino acids imbalance in piglets, and the dietary electrolyte may be a key factor in the impact of the LP diet on piglet growth performance and intestinal health.

Arginine-NO metabolites are associated with morbidity in single ventricle infants undergoing stage 2 palliation.

Infants with single ventricle heart disease (SVHD) suffer morbidity from insufficient pulmonary blood flow, which may be related to impaired arginine metabolism. No prior study has reported quantitative mapping of arginine metabolites to evaluate the relationship between circulating metabolite levels and outcomes. Prospective cohort study of 75 SVHD cases peri-Stage 2 and 50 healthy controls. We targeted pre- and post-op absolute serum quantification of 9 key members of the arginine metabolism pathway by tandem mass spectrometry. Primary outcomes were length of stay (LOS) and post-Stage 2 hypoxemia. Pre-op cases showed alteration in 6 metabolites including decreased arginine and increased asymmetric dimethyl arginine (ADMA) levels compared to controls. Post-op cases demonstrated decreased arginine and citrulline levels persisting through 48 h. Adjusting for clinical variables, lower pre-op and 2 h post-op concentrations of multiple metabolites, including arginine and citrulline, were associated with longer post-op LOS (p < 0.01). Increased ADMA at 24 h was associated with greater post-op hypoxemia burden (p < 0.05). Arginine metabolism is impaired in interstage SVHD infants and is further deranged following Stage 2 palliation. Patients with greater metabolite alterations experience greater post-op morbidity. Decreased arginine metabolism may be an important driver of pathology in SVHD. Interstage infants with SVHD have significantly altered arginine-nitric oxide metabolism compared to healthy children with deficiency of multiple pathway intermediates persisting through 48 h post-Stage 2 palliation. After controlling for clinical covariates and classic catheterization-derived predictors of Stage 2 readiness, both lower pre-operation and lower post-operation circulating metabolite levels were associated with longer post-Stage 2 LOS while increased post-Stage 2 ADMA concentration was associated with greater post-op hypoxemia. Arginine metabolism mapping offers potential for development using personalized medicine strategies as a biomarker of Stage 2 readiness and therapeutic target to improve pulmonary vascular health in infants with SVHD.