Amino Acid Absorption Research Articles

Probiotic BC30 Improves Amino Acid Absorption from Plant Protein Concentrate in Older Women

Weizmannia coagulans GBI-30, 6086 (BC30) has previously been shown to increase protein digestion in an in vitro model of the stomach and small intestine and amino acid appearance in healthy men and women after ingestion of milk protein concentrate. The impact of ingesting BC30 with other protein sources or in other demographics is largely unknown. The purpose of this study was to examine the impact of adding BC30 to a 20-g dose of a blend of rice and pea protein on postprandial changes in blood amino acids concentrations in healthy, older women. Healthy, older females (n = 30, 58.5 ± 5.2 years, 165.4 ± 6.8 cm, 65.6 ± 8.8 kg, 23.7 ± 3.2 kg/m2) completed two separate 14-day supplementation protocols separated by a 3-week washout period. Participants were instructed to ingest a 20-g protein dose of a blend of rice and pea protein concentrates (ProDiem Plant Protein Solutions, Kerry) with (PPCBC30) or without (PPC) the addition of 1 × 109 CFU BC30 (Kerry). Body composition and demographics were assessed upon arrival to the laboratory. Upon ingestion of their final assigned supplemental dose, blood samples were taken at 0 (baseline), 30-, 60-, 90-, 120-, 180-, and 240-min post-consumption and analyzed for amino acid concentrations. Alanine (p = 0.018), tryptophan (p = 0.003), cysteine (p = 0.041), essential amino acids (p = 0.050), and total amino acids (p = 0.039) all exhibited significantly (p ≤ 0.05) greater AUC with PPCBC30 when compared to PPC. In addition, tryptophan (p = 0.003), cysteine (p = 0.021), essential amino acids (p = 0.049), and total amino acids (p = 0.035) displayed significantly greater (p ≤ 0.05) concentration maximum (CMax) values in PPCBC30 when compared to PPC. Finally, time to reach CMax (TMax) was similar between conditions with 80% of all measured amino acids and amino acid combinations achieving CMax at a similar time (~ 60 min). Only phenylalanine TMax was found to be different (p = 0.01) between the two conditions with PPC displaying a greater proportion of TMax values after 30 min. Following qualitative (non-inferential) assessment, 88% of all measured outcomes achieved a higher AUC with PPCBC30 and 100% of all outcomes achieved a higher CMax with PPCBC30. In concert with previous findings in a younger mixed gender cohort with milk protein, the addition of BC30 to a daily 20-g dose of plant protein concentrate in healthy older women improved AUC and CMax values in several individual amino acids and amino acid combinations. Retrospectively registered on April 6, 2022, at ClinicalTrials.gov as NCT05313178.

Apparent and standardised ileal amino acid digestibilities in heat-stressed pigs fed wheat-soybean meal diets supplemented with l-arginine and dl-methionine.

Heat stress (HS) exposure may damage the small intestine epithelia of pigs affecting the digestibility and absorption of amino acids (AA). Arg and Met can enhance antioxidant and intestinal cell proliferation activity, thus supplementing them in diets might alleviate epithelial damage and correct the reduced AA digestibility. The effect of adding extra l-Arg and dl-Met to diets on the apparent (AID) and standardised ileal digestibility (SID) of AA was analysed in a 10-day experiment conducted with 10 ileal-cannulated HS pigs (25.3 ± 2.4 kg body weight). The pigs were divided into two treatments: Control, wheat-soybean meal diet supplemented with l-Lys, l-Thr, dl-Metand l-Trp; and control diet plus 0.20% l-Arg and 0.20% dl-Met (Arg + Met). Following an 8-day diet adaptation period, ileal digesta was continuously collected for 12 h, starting at 0700, on Days 9 and 10. All pigs were daily exposed to 29.6-36.1°C; ileal temperature was continuously monitored at 15-min intervals. Feed was provided twice a day. The ileal temperature ranged from 40.3 to 41.5°C. Daily ileal outflow of His, Ile, Leu, Phe, Thr, Serand Tyr decreased (p < 0.05), and that of Arg, Valand Pro tended to decrease (p < 0.10) in the Arg + Met pigs. The AID of Arg, His, Met, Thrand Tyr, and the SID of His, Met, and Thr increased in pigs fed the Arg + Met diet (p < 0.05). Thr and Val had the lowest AID values whereas Arg, Met, and Lys had the highest values. Arg (r = 0.64) and Met (r = 0.84) intake were highly correlated with their AID values; Met intake was highly correlated with its SID value (r = 0.72). Valine and Arg had the lowest whereas Arg had the highest SID values. In conclusion, supplementing l-Arg and dl-Met above the requirement decreases the ileal outflow of several AA, and increases the AID and SID of some essential AA in HS pigs.

Free Amino Acid–Enriched Diets Containing Rapidly but Not Slowly Digested Carbohydrate Promote Amino Acid Absorption from Intestine and Net Fluxes across Skeletal Muscle of Pigs

The approach to matching appropriate carbohydrates alongside free amino acids to achieve optimal muscle growth remains unclear. We investigated whether the consumption of a diet containing rapidly digested carbohydrate and free amino acids can enhance intestinal absorption and muscular uptake of amino acids in pigs. Twelve barrows (28 kg; 11 wk old) with catheters installed in the portal vein, mesenteric vein, femoral artery, and femoral vein were randomly assigned to consume 1 of 2 free amino acid-enriched diets (3.34%) containing rapidly [waxy corn starch (WCS)] or slowly [pea starch (PS)] digested carbohydrate for 27 d. Blood was collected to determine the fluxes of plasma glucose and amino acids across the portal vein and the hindlimb muscle. Dietary in vitro carbohydrate digestive rates were also determined. Data were analyzed using repeated-measures (time × group) ANOVA. Carbohydrate in vitro cumulative digestibility at 30 and 240 min was 69.00% and 95.25% for WCS and 23.25% and 81.15% for PS, respectively. The animal experiment presented WCS increased individual amino acids (lysine, 0.67 compared with 0.53 mmol/min; threonine, 0.40 compared with 0.29 mmol/min; isoleucine, 0.33 compared with 0.22 mmol/min; glutamate, 0.51 compared with 0.35 mmol/min; and proline, 0.51 compared with 0.27 mmol/min), essential amino acid (EAA; 3.26 compared with 2.65 mmol/min), and branched-chain amino acid (BCAA; 0.86 compared with 0.65 mmol/min) fluxes across the portal vein during 8 h postprandial, as well as individual amino acids (isoleucine, 0.08 compared with 0.02 mmol/min; leucine, 0.06 compared with 0.02 mmol/min; and glutamine, 0.44 compared with 0.25 mmol/min), EAA (0.50 compared with 0.21 mmol/min), and BCAA (0.17 compared with 0.06 mmol/min) net fluxes across the hindlimb muscle during 8 h postprandial compared with PS (P < 0.05). A diet containing rapidly digested carbohydrate and free amino acids can promote intestinal absorption and net fluxes across hindlimb muscle of amino acids in pigs.

Time Courses of Gastric Volume and Content after Different Types of Casein Ingestion in Healthy Men: A Randomized Crossover Study

Few studies have evaluated differences in the curd-forming ability of casein on gastric volume and content directly after ingestion in humans. This study evaluated the time course of gastric volume and curd conditions in the stomach after protein ingestion. This was an open-labeled, randomized crossover trial. Ten healthy men [age: 33.4 ± 7.3 y; BMI (kg/m2): 21.9 ± 0.9] received 350 g of 3 isonitrogenous and isocaloric protein drinks containing 30 g micellar casein (MCN), sodium caseinate (SCN), or whey protein concentrate (WPC). The gastric antrum cross-sectional area (CSA) and curd in the stomach were measured using ultrasonography within 5 h after ingestion. The differences between test foods were tested using the MIXED model and post hoc tests using Fisher's protected least significant difference. The incremental AUC of the gastric antrum CSA after MCN ingestion was 1.3-fold and 1.5-fold higher than that after the ingestion of SCN and WPC, respectively (both P < 0.05), but not different between SCN and WPC. The number of participants with curds ≥20 mm with a high echogenicity clot observed in the stomach within 5 h after MCN ingestion was significantly greater than that after the ingestion of other proteins (n = 9 for MCN, n = 2 for SCN, and n = 0 for WPC; bothP < 0.01). The regression line slopes on total plasma amino acid concentration and gastric antrum CSA were significantly different between the participants with and without curds. In contrast to SCN and WPC, MCN ingestion resulted in slow kinetics of gastric antrum CSA. Differences in curd formation of casein in the stomach affect gastric emptying and plasma amino acid absorption kinetics after ingestion in healthy men. This trial was registered at University Hospital Medical Information Network Clinical Trials Registry as UMIN000038388 (https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000043746).

Excretion of excess nitrogen and increased survival by loss of SLC6A19 in a mouse model of ornithine transcarbamylase deficiency.

Protein catabolism ultimately yields toxic ammonia, which must be converted to urea by the liver for renal excretion. In extrahepatic tissues, ammonia is temporarily converted primarily to glutamine for subsequent hepatic extraction. Urea cycle disorders (UCDs) are inborn errors of metabolism causing impaired ureagenesis, leading to neurotoxic accumulation of ammonia and brain glutamine. Treatment includes dietary protein restriction and oral "ammonia scavengers." These scavengers chemically combine with glutamine and glycine to yield excretable products, creating an alternate pathway of waste nitrogen disposal. The amino acid transporter SLC6A19 is responsible for >95% of absorption and reabsorption of free neutral amino acids in the small intestine and kidney, respectively. Genetic SLC6A19 deficiency causes massive neutral aminoaciduria but is typically benign. We hypothesized that inhibiting SLC6A19 would open a novel and effective alternate pathway of waste nitrogen disposal. To test this, we crossed SLC6A19 knockout (KO) mice with spfash mice, a model of ornithine transcarbamylase (OTC) deficiency. Loss of SLC6A19 in spfash mice normalized plasma ammonia and brain glutamine and increased median survival in response to a high protein diet from 7 to 97 days. While induced excretion of amino acid nitrogen is likely the primary therapeutic mechanism, reduced intestinal absorption of dietary free amino acids, and decreased muscle protein turnover due to loss of SLC6A19 may also play a role. In summary, the results suggest that SLC6A19 inhibition represents a promising approach to treating UCDs and related aminoacidopathies.

Caloric Restriction, Friend or Foe: Effects on Metabolic Status in Association with the Intestinal Microbiome and Metabolome.

Daily calorie restriction (CR) has shown benefits on weight loss and alleviation of metabolic disorders. We investigated the effects of three CR regimens, i.e., 20% (CR-20), 40% (CR-40), and 60% (CR-60) less than the average daily calorie intake, respectively, on the metabolic parameters, gut microbiome composition, and its related metabolites in healthy mice. Compared with mice fed ad libitum (AL), CR dose-dependently reduced the body weight, and weights of liver and epididymal adipose tissues, and enhanced the insulin sensitivity, glucose tolerance, and lipid homeostasis. Moreover, expression levels of intestinal tight junction proteins (i.e., ZO-1, claudin, and occludin) were significantly promoted by CR than those of AL mice, demonstrating the CR-induced improvement of the intestinal barrier integrity. CR contributed to the enrichment of beneficial microbiota (e.g., Lactobacillus, Bacteroides, and Akkermansia) and increased propionic acid levels. Notably, CR-60 deleteriously caused liver injury, and enhanced hepatic inflammatory cytokines (i.e., IL-1, IL-6, and TNF-α) and lipopolysaccharides, which were accompanied by high levels of trimethylamine (TMA) and trimethylamine oxide (TMAO) in relation to CR-60-altered gut microbiota structure and fecal metabolome. Additionally, we found differential impacts of CR-20, -40, or -60 on amino acid absorption and metabolism. Our findings support the health-promoting benefits of 60-80% daily calorie intake on the metabolic status by regulating the gut microbiota in healthy mice. However, excessive CR caused liver injury and gut microbiota-dependent elevation of TMAO. The differential effects of CR regimens on the intestinal microbiome and fecal metabolome provide novel insights into the dietary pattern-gut microbiome interactions linked with host metabolism.

The beneficial effects of exogenous protease K originated from Parengyodontium album on growth performance of grass carp (Ctenopharyngodon idella) in relation to the enhanced intestinal digestion and absorption capacities

The study was primarily designed to analyze the effect of exogenous protease K on growth performance, amino acid metabolism, digestion and absorption capacities, expression of amino acid transporters related genes and proteins in intestine of sub-adult grass carp (Ctenopharyngodon idella). Six experimental diets with protease K (0, 3000, 6000, 9000, 12,000 and 15,000 U/kg) were fed to 450 grass carp (619.51 ± 0.54 g) for 60 days. The results indicated that the highest value of final body weight, percent weight gain (PWG), specific growth rate, protein efficiency ratio, activity of hepatopancreas glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase, and the lowest concentration of plasma ammonia were observed in groups with protease K of 6000 and 9000 U/kg. Meanwhile, the groups with 6000 and 9000 U/kg protease K exhibited the highest activities of digestive and brush border membrane enzymes in the three intestinal segments, as well as the highest value of intestinal somatic index and intestinal length index. The highest concentration of free amino acid in the serum and the lowest in intestine were observed in groups with supplementation of protease K 6000 and 9000 U/kg, which might be related to the up-regulated mRNA level and protein expression of intestinal amino acid transporters (SLC1A5, SLC7A6, SLC1A3 et al) in these groups. Furthermore, optimal levels of protease K up-regulated the mRNA levels of target of rapamycin (TOR), S6 kinase 1 (S6K1), and protein expression of TOR and phosphorylation TORSer2448, but reduced the mRNA level of 4E binding protein 1 (4EBP1). In summary, optimal levels of exogenous protease K was found to be conducive to facilitate the improvement of growth performance probably via enhancing digestion and absorption capacity, and utilization of amino acid in sub-adult grass carp. In addition, using quadratic regression analysis of PWG and alkaline phosphatase in the midgut, the optimum addition of protease K for the sub-adult grass carp were noted to be 7380.82 and 7406.44 U/kg, respectively.

Comparative Metagenomics and Metabolomes Reveals Abnormal Metabolism Activity Is Associated with Gut Microbiota in Alzheimer's Disease Mice.

A common symptom in Alzheimer’s disease (AD) is cognitive decline, of which the potential pathogenesis remains unclear. In order to understand the mechanism of gut microbiota in AD, it is necessary to clarify the relationship between gut microbiota and metabolites. Behavioral tests, pathological examination, metagenomics, and metabolomics were applied to analyze the difference of gut microbiota and metabolome between APPswe/PS1ΔE9 (PAP) mice with cognitive decline and age-matched controls, and their possible correlations. Our results showed that PAP mice and health mice had different structures of the bacterial communities in the gut. The abundances and diversities of the bacterial communities in health mice were higher than in PAP mice by metagenomics analysis. The abundances of Libanicoccus massiliensis, Paraprevotella clara, and Lactobacillus amylovorus were significantly increased in PAP mice, while the abundances of Turicibacter sanguinis, Dubosiella newyorkensis, and Prevotella oris were greatly reduced. Furthermore, PAP mice possessed peculiar metabolic phenotypes in stool, serum, and hippocampus relative to WT mice, as is demonstrated by alterations in neurotransmitters metabolism, lipid metabolism, aromatic amino acids metabolism, energy metabolism, vitamin digestion and absorption, and bile metabolism. Microbiota–host metabolic correlation analysis suggests that abnormal metabolism in stool, serum, and hippocampus of PAP mice may be modulated by the gut microbiota, especially T. sanguinis, D. newyorkensis, and P. oris. Therefore, abnormal metabolism activity is associated with gut microbiota in Alzheimer’s disease mice. Our results imply that modifying host metabolism through targeting gut microbiota may be a novel and viable strategy for the prevention and treatment of AD in the future.

Urinary angiotensin-converting enzyme 2 and metabolomics in COVID-19-mediated kidney injury.

BackgroundAngiotensin-converting enzyme 2 (ACE2), the receptor for SARS-CoV-2, is highly expressed in the kidneys. Beyond serving as a crucial endogenous regulator of the renin-angiotensin system, ACE2 also possess a unique function to facilitate amino acid absorption. Our observational study sought to explore the relationship between urine ACE2 (uACE2) and renal outcomes in COVID-19.MethodsIn a cohort of 104 patients with COVID-19 without acute kidney injury (AKI), 43 patients with COVID-19-mediated AKI, and 36 non-COVID-19 controls, we measured uACE2, urine tumor necrosis factor receptors I and II (uTNF-RI and uTNF-RII), neutrophil gelatinase-associated lipocalin (uNGAL). We also assessed ACE2 staining in autopsy kidney samples and generated a propensity-score matched subgroup of patients to perform a targeted urine metabolomic study to describe the characteristic signature of COVID-19.ResultsuACE2 is increased in patients with COVID-19, and further increased in those that developed AKI. After adjusting uACE2 levels for age, sex and previous comorbidities, increased uACE2 was independently associated with over 3-fold higher risk of developing AKI (OR 3.05, 95%CI:1.23‒7.58,p = 0.017). Increased uACE2 corresponded to a tubular loss of ACE2 in kidney sections and strongly correlated with uTNF-RI and uTNF-RII. Urine quantitative metabolome analysis revealed an increased excretion of essential amino acids in patients with COVID-19, including leucine, isoleucine, tryptophan and phenylalanine. Additionally, a strong correlation was observed between urine amino acids and uACE2.ConclusionsElevated uACE2 is related to AKI in patients with COVID-19. The loss of tubular ACE2 during SARS-CoV-2 infection demonstrates a potential link between aminoaciduria and proximal tubular injury.

Serum diamine oxidase activity derived from response to chemotherapy affects adverse events and serum amino acid levels.

The relationship between activity of the small intestinal villi and the effectiveness of chemotherapy remains unclear. This study aimed to investigate how serum diamine oxidase (DAO) activity affects antitumor effects, adverse events, and amino acid absorption. We performed a single-center prospective cohort study that enrolled 50 patients with esophageal cancer (EC) receiving docetaxel, cisplatin, and 5-fluorouracil therapy. We determined the cut-off value of serum DAO activity contributing to a response to chemotherapy using a generalized additive model. Additionally, we compared adverse events, inflammatory markers, blood amino acid levels, and quality of life between the high and low DAO activity groups during chemotherapy. The cut-off value of serum DAO activity at the first visit that contributed to a chemotherapy response was 6.5 units/L. Leukopenia and neutropenia of grade ≥ 3 were significantly higher in the DAO low (< 6.5 units/L) group (p = 0.044, 0.017, respectively). Interleukin-6 was significantly lower in the DAO high (≥ 6.5 units/L) group at the first visit and at 4weeks after the end of chemotherapy (p = 0.039, 0.011, respectively). Glutamine was higher in the DAO high group at all measurement points during chemotherapy. Fatigue was significantly lower in the DAO high group (p = 0.001). Serum DAO activity may be a predictor of the response to chemotherapy in patients with EC. The absorption capacity of amino acids was maintained in the group with high DAO activity, which may have contributed to the anti-inflammatory effect and provided a background for reducing adverse events.

Effects of fishmeal replacement by Clostridium autoethanogenum protein on the growth, digestibility, serum free amino acid and gene expression related to protein metabolism of obscure pufferfish (Takifugu obscurus)

A 63-day feeding trial was conducted to evaluate the effect of Clostridium autoethanogenum protein (CAP) on the growth, digestibility, postprandial free amino acid concentrations in serum, and gene expression related to protein metabolism in obscure pufferfish (Takifugu obscurus). The basal diet with 420 g/kg of fishmeal was used as the control diet (CAP0), and then 20 % (CAP20), 40 % (CAP40) and 80 % (CAP80) dietary fishmeal were replaced by CAP. Compared with diet CAP0, the growth and feed utilization was not affected in fish fed diet CAP20, but was significantly reduced in fish fed diets CAP40 and CAP80 (P < 0.05). The apparent digestibility coefficients (ADCs) of dry matter and protein in the CAP80 group were significantly lower (P < 0.05) than those of the other three groups, and the ADC of lipid was significantly decreased (P < 0.05) in the CAP40 and CAP80 groups. Fish fed diets CAP40 and CAP80 had lower taurine content in muscle compared to those fed diets CAP0 and CAP20 (P < 0.05). Higher free essential amino acid concentrations in serum were observed in fish fed diet CAP80 compared to the other diets at 2 h after refeeding (P < 0.05). Fish fed diets CAP40 and CAP80 showed lower hardness and gumminess in muscle than those fed the other diets (P < 0.05). The expression of peptide transporter1 (PepT1) in intestine and target of rapamycin (TOR) in muscle were significantly up-regulated in the CAP40 groups compared to the control (CAP0) (P < 0.05). However, relative expressions of 4F2 heavy chain (4F2hC), L-type amino acid transporter 2 (y+LAT2) and T-type amino acid transporter1(TAT1) in intestine were not significantly affected by graded levels of CAP (P > 0.05). The inclusion of CAP did not significantly affect the expression of ribosomal protein S6 kinase 1 (S6K1), eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) and 4E-BP2 (P > 0.05) in muscle and liver. In summary, in a basal diet containing 420 g/kg fishmeal, 20 % fishmeal in diets could be successfully substituted by CAP, while high-level CAP decreased the growth, feed utilization and digestibility in juvenile obscure pufferfish. The main reasons for the inhibition of growth performance were probably that excessive CAP caused dietary taurine deficiency and the imbalance of amino acid absorption.

Protein Matrix Impacts Essential Amino Acid Response To Feeding

It is well established that muscle protein turnover is highly response to increases in plasma essential amino acids (EAA). Digestion and amino acid absorption kinetics appear to strongly modulate post-prandial muscle protein synthesis. Despite this relationship, little is known about the effects of the protein matrix on plasma EAA appearance. PURPOSE: To assess if protein matrix alters plasma EAA pharmacokinetics (PK). METHODS: 24 healthy young individuals (24.7 ± 4.7y; BMI = 24.6 ± 3.2 kg/m2) completed this study. Participants consumed one of the following protein matrices: whey protein isolate (W; 6.8 g of EAA), beef sirloin (B; 7.0 g of EAA), or free form EAA enriched W (FW; 5.6 g of EAA). Blood samples were collected before and four hours following the ingestion of W, B, and FW. Plasma EAA were analyzed via LC-MS/MS. Standard pK values were calculated: area under the curve above baseline (AUCi), max EAA concentration (Cmax), EAA concentration change from baseline to EAACmax (ΔEAA), rate to Cmax, and time to Cmax. To examine group differences in EAA pK a one-way analysis of variance with Tukey post hoc test was performed with significance accepted at P ≤ 0.05. RESULTS: Significant group differences were noted for all measured pK (p ≤ 0.005). Post hoc comparisons indicated AUCi was significantly lower in W (50705.6 ± 13483.3 μmol/L/min) as compared to FW (84793.8 ± 15989.7 μmol/L/min; p = 0.004) and B (77084.6 ± 25076.0 μmol/L/min; p = 0.028). Cmax, ΔEAA, and rate to Cmax was significantly higher in FW (Cmax = 1,920 ± 242.6 μmol/L; ΔEAA = 1012.4 ± 200.8 μmol/L; rate to Cmax = 30.1 ± 13.0 μmol/L/min) as compared to W (Cmax = 1343.1 ± 144.4 μmol/L, p ≤ 0.001; ΔEAA = 556.9 ± 160.1 μmol/L, p ≤ 0.001; rate to Cmax = 13.6 ± 7.6 μmol/L/min, p = 0.003) and B (Cmax = 1339.9 ± 213.5 μmol/L, p ≤ 0.001; ΔEAA = 543.8 ± 164.2 μmol/L, p ≤ 0.001; rate to Cmax = 4.9 ± 2.7 μmol/L/min, p ≤ 0.001). Lastly, the time to Cmax was slowest in B (135.0 ± 62.1 mins) as compared to W (47.5 ± 14.9 mins; p ≤ 0.001) and FW (36.3 ± 7.4 mins; p ≤ 0.001). CONCLUSION: Despite similar EAA content, pharmacokinetics were significantly different between treatments. Despite the lowest EAA content, FW resulted in the greatest plasma EAA availability and quickest time to peak. These results indicate that protein/amino acid digestion is a primary determinant of plasma EAA availability.

12. Evaluation of the NASEM 2021 dairy nutrient requirements model in lactating dairy cows fed diets with differing predicted absorbed amino acid efficiencies

12. Evaluation of the NASEM 2021 dairy nutrient requirements model in lactating dairy cows fed diets with differing predicted absorbed amino acid efficiencies

Changes in the expression of certain osmosensitive channel and transporter genes in primary hepatocytes of air-breathing catfish, Clarias magur: A strategy to adapt under osmotic stress

Environmental salinity/osmolarity is an important abiotic ecological factor that affects several metabolic activities of aquatic organisms. Air-breathing magur catfish (Clarias magur) frequently encounter a wide range of external osmolarity changes in their natural habitats as well as internal osmolarity due to the absorption of amino acids and other metabolites through the intestine. The major objective of the present investigation was to demonstrate the influences of anisotonicity exposure on the expression of certain isoforms of aquaporin (AQP) channels (aqp7, 8, and 11), taurine transporter (TauT, slc6a6), urea transporter (UT1, slc14a1) and Na+-K+-ATPase (NKA, atp1a1, and atp1b1) transporter genes, and their translated protein products in the primary hepatocytes of magur catfish. These genes are known to play major roles in cellular volume regulation and water homeostasis under osmotic stress. Exposure of primary hepatocytes to hypertonic medium (+40 mOsmol/L) for a period of 48 h resulted in a significant increase in the expression of aqp7, aqp8, aqp11, slc6a6, slc14a1, atp1a1, and atp1b1 genes, as evidenced by a rise in the levels of both mRNAs of all the above-mentioned genes, and also their translated protein products compared to isotonic controls. However, exposure of primary hepatocytes to hypotonic medium (_40 mOsmol/L) for the same period led to a significant decrease in mRNA levels for aqp7, aqp8, aqp11, slc6a6, and slc14a1 genes, and also their translated protein products compared to isotonic controls as a consequence of downregulation of corresponding genes. Interestingly, NKA enzyme activity in primary hepatocytes was found to increase significantly after exposure to both hypertonic and hypotonic media. Hypertonicity induced the genes for α- and β-subunits of this enzyme both at transcriptional and translational levels. In contrast, hypotonicity induced only the atp1a1 gene and the expression of corresponding translated protein without causing any changes in the expression of the atp1b1 gene. Thus, it may be contemplated that osmotic stress, which results due to anisotonicity of the external environment or in the body fluids, leads to differential expression of different osmosensitive channels such as AQPs, and transporters such as TauT, UT1, UT2, and NKA in hepatic cells of magur catfish and work in coordination to defend the osmotically-induced changes of cellular volume. These regulatory responses of channels and transporters could be one of the vital molecular mechanisms that may have evolved in this catfish to defend against the osmotically-induced stresses.

Aristolochic acid-induced nephropathy is attenuated in mice lacking the neutral amino acid transporter B0AT1 (Slc6a19).

B0AT1 (Slc6a19) mediates absorption of neutral amino acids in the small intestine and in the kidneys, where it is primarily expressed in early proximal tubules (S1-S2). To determine the role of B0AT1 in nephropathy induced by aristolochic acid (AA), which targets the proximal tubule, littermate female B0AT1-deficient (Slc6a19-/-), heterozygous (Slc6a19+/-), and wild-type (WT) mice were administered AA (10 mg/kg ip) or vehicle every 3 days for 3 wk, and analyses were performed after the last injection or 3 wk later. Vehicle-treated mice lacking Slc6a19 showed normal body and kidney weight and plasma creatinine versus WT mice. The urinary glucose-to-creatinine ratio (UGCR) and urinary albumin-to-creatinine ratio (UACR) were two to four times higher in vehicle-treated Slc6a19-/- versus WT mice, associated with lesser expression of early proximal transporters Na+-glucose cotransporter 2 and megalin, respectively. AA caused tubular injury independently of B0AT1, including robust increases in cortical mRNA expression of p53, p21, and hepatitis A virus cellular receptor 1 (Havcr1), downregulation of related proximal tubule amino acid transporters B0AT2 (Slc6a15), B0AT3 (Slc6a18), and Slc7a9, and modest histological tubular damage and a rise in plasma creatinine. Absence of B0AT1, however, attenuated AA-induced cortical upregulation of mRNA markers of senescence (p16), inflammation [lipocalin 2 (Lcn2), C-C motif chemokine ligand 2 (Ccl2), and C-C motif chemokine receptor 2 (Ccr2)], and fibrosis [tissue inhibitor of metallopeptidase 1 (Timp1), transforming growth factor-β1 (Tgfb1), and collagen type I-α1 (Col1a1)], associated with lesser fibrosis staining, lesser suppression of proximal tubular organic anion transporter 1, restoration of Na+-glucose cotransporter 2 expression, and prevention of the AA-induced fivefold increase in the urinary albumin-to-creatinine ratio observed in WT mice. The data suggest that proximal tubular B0AT1 is important for the physiology of renal glucose and albumin retention but potentially deleterious for the kidney response following AA-induced kidney injury.NEW & NOTEWORTHY Based on insights from studies manipulating glucose transport, the hypothesis has been proposed that inhibiting intestinal uptake or renal reabsorption of energy substrates has unique therapeutic potential to improve metabolic disease and kidney outcome in response to injury. The present study takes this idea to B0AT1, the major transporter for neutral amino acids in the intestine and kidney, and shows that its absence attenuates aristolochic acid-induced nephropathy.

Dynamic alterations in the donkey fecal bacteria community and metabolome characteristics during gestation.

In donkeys, the gestation period is a dynamic and precisely coordinated process involving systemic and local alterations. Both the gut microbiota and its link with blood metabolites are thought to play significant roles in maintaining maternal health and supporting fetal development during the gestation period. This study was conducted to evaluate gut microbiota changes and the correlation with plasma metabolites in Dezhou donkeys during the gestation period. The donkeys were divided into the four following groups according to their pregnancy stages: the non-pregnant (NP), early stage of pregnancy (P1), middle stage of pregnancy (P2), and late stage of pregnancy (P3) groups. A total of 24 (n = 6 per group) samples of donkey feces and plasma were collected. The results showed that the diversity (Shannon index) of fecal bacteria significantly increased throughout the gestation period. The phyla Spirochaetota and Fibrobacterota varied significantly according to the stages of pregnancy (p < 0.05). At the genus level, the abundance of Treponema in pregnant donkeys was greater than that in non-pregnant donkeys (p < 0.05), and the genus Streptococcus reached its maximum abundance in the P2 period (p < 0.05). The abundance of Ruminococcaceae_NK4A214_group and norank_f_norank_o_WCHB1-41 linearly increased with the progression of pregnancy (p < 0.05). In addition, the host plasma metabolome was altered significantly during the gestation period. Testolic acid, estradiol-17beta 3-sulfate, equol 7'-o-glucuronide, equol 4'-o-glucuronide, estrone, estrone 3-glucuronide, and estradiol were the most significant differential enriched metabolites, and they increased gradually as gestation progressed. The altered metabolites were mainly enriched in pathways matched to bile secretion, ABC transporters, amino acid metabolism, protein digestion and absorption, mineral absorption, fatty acid degradation, glycerophospholipid metabolism, and steroid hormone biosynthesis. We also found a significant correlation between the shifts in donkey fecal bacteria and changes in the host metabolism. In summary, this study provided systematic data on the fecal bacterial changes and host plasma metabolism of donkeys throughout pregnancy. The results indicated that host-bacteria interactions during the gestation period influence the host metabolism. These interactions benefit the pregnant donkeys by providing a sufficient supply of nutrients and energy for fetal growth and maternal health.

In vitro assessment of the probiotic properties of an industrial preparation containing Lacticaseibacillus paracasei in the context of athlete health.

Intense physical activity is often associated with undesirable physiological changes, including increased inflammation, transient immunodepression, increased susceptibility to infections, altered intestinal barrier integrity, and increased oxidative stress. Several trials suggested that probiotics supplementation may have beneficial effects on sport-associated gastro-intestinal and immune disorders. Recently, in a placebo-controlled human trial, the AminoAlta™ probiotic formulation (AApf) was demonstrated to increase the absorption of amino acids from pea protein, suggesting that the administration of AApf could overcome the compositional limitations of plant proteins. In this study, human cell line models were used to assess in vitro the potential capacity of AApf to protect from the physiological damages that an intense physical activity may cause. The obtained results revealed that the bacteria in the AApf have the ability to adhere to differentiated Caco-2 epithelial cell layer. In addition, the AApf was shown to reduce the activation of NF-κB in Caco-2 cells under inflammatory stimulation. Notably, this anti-inflammatory activity was enhanced in the presence of partially hydrolyzed plant proteins. The AApf also triggered the expression of cytokines by the THP-1 macrophage model in a dose-dependent manner. In particular, the expression of cytokines IL-1β, IL-6, and TNF-α was higher than that of the regulatory cytokine IL-10, resembling a cytokine profile characteristic of M1 phenotype, which typically intervene in counteracting bacterial and viral infections. Finally, AApf was shown to reduce transepithelial permeability and increase superoxide dismutase activity in the Caco-2 cell model. In conclusion, this study suggests that the AApf may potentially provide a spectrum of benefits useful to dampen the gastro-intestinal and immune detrimental consequences of an intense physical activity.

A critical role of AMP-activated protein kinase in regulating intestinal nutrient absorption, barrier function, and intestinal diseases.

As one of the most important organs in animals, the intestine is responsible for nutrient absorption and acts as a barrier between the body and the environment. Intestinal physiology and function require the participation of energy. 5'-adenosine monophosphate-activated protein kinase (AMPK), a classical and highly expressed energy regulator in intestinal cells, regulates the process of nutrient absorption and barrier function and is also involved in the therapy of intestinal diseases. Studies have yielded findings that AMPK regulates the absorption of glucose, amino acids, and fatty acids in the intestine primarily by regulating transportation systems, as we detailed here. Moreover, AMPK is involved in the regulation of the intestinal mechanical barrier and immune barrier through manipulating the expression of tight junctions, antimicrobial peptides, and secretory immunoglobulins. In addition, AMPK also participates in the regulation of intestinal diseases, which indicates thatAMPK is a promising therapeutic target for intestinal diseases and cancer. In this review, we summarized the current understanding regarding how AMPK regulates intestinal nutrient absorption, barrier function, and intestinal diseases.

Research and Application of Factory Hydroponic Technology in Wheatgrass Greenhouse

Conversion of farmland to forest is one of the important policies of China’s western development strategy, which is of great significance to the protection of ecological environment in western China. In the context of this era, the traditional grazing-based breeding method that the western region has long adhered to needs to be replaced by the factory-based house feeding with large-scale construction of forage bases. On the basis of a self-developed multi-layer three-dimensional intelligent environmental control system, this study comprehensively optimized the temperature and humidity control system, automatic micro-spraying system, intelligent ventilation system and automatic light filling system, so as to develop an efficient wheat hydroponic planting system. Based on the above planting system, it only takes 7 days from sowing to harvesting. The roots, stems and leaves of wheat grains are all fodder, and 7 kilo-grams of green forage grass can be produced by per kilogram of wheat. In addition, through hydroponic transformation of wheat, protein starch, which is difficult or inefficient to be absorbed in the form of wheat seed, can be transformed into easily absorbed amino acids and glucose. Meanwhile, the vitamin content of green feed is significantly increased, which is of great significance to improve the feed biological conversion rate.

Dietary Concentrate-to-Forage Ratio Affects Rumen Bacterial Community Composition and Metabolome of Yaks.

Changes in dietary composition affect the rumen microbiota in ruminants. However, information on the effects of dietary concentrate-to-forage ratio changes on yak rumen bacteria and metabolites is limited. This study characterized the effect of three different dietary concentrate-to-forage ratios (50:50, C50 group; 65:35, C65 group; 80:20, C80 group) on yak rumen fluid microbiota and metabolites using 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS) analyses. Rumen fermentation parameters and the abundance of rumen bacteria were affected by changes in the dietary concentrate-to-forage ratio, and there was a strong correlation between them. At the genus level, higher relative abundances of norank_f__F082, NK4A214_group, Lachnospiraceae_NK3A20_group, Acetitomaculum, and norank_f__norank_o__Clostridia_UCG-014 were observed with a high dietary concentrate-to-forage ratio (P < 0.05). Combined metabolomic and enrichment analyses showed that changes in the dietary concentrate-to-forage ratio significantly affected rumen metabolites related to amino acid metabolism, protein digestion and absorption, carbohydrate metabolism, lipid metabolism, and purine metabolism. Compared with the C50 group, 3-methylindole, pantothenic acid, D-pantothenic acid, and 20-hydroxy-leukotriene E4 were downregulated in the C65 group, while spermine and ribose 1-phosphate were upregulated. Compared to the C50 group, Xanthurenic acid, tyramine, ascorbic acid, D-glucuronic acid, 6-keto-prostaglandin F1a, lipoxin B4, and deoxyadenosine monophosphate were upregulated in the C80 group, while 3-methylindole and 20-hydroxy-leukotriene E4 were downregulated. All metabolites (Xanthurenic acid, L-Valine, N-Acetyl-L-glutamate 5-semialdehyde, N-Acetyl-L-glutamic acid, Tyramine, 6-Keto-prostaglandin F1a, Lipoxin B4, Xanthosine, Thymine, Deoxyinosine, and Uric acid) were upregulated in the C80 group compared with the C65 group. Correlation analysis of microorganisms and metabolites provided new insights into the function of rumen bacteria, as well as a theoretical basis for formulating more scientifically appropriate feeding strategies for yak.