Supply Of Arg Research Articles

The arginine decarboxylase gene CsADC1, associated with the polyamine pathway, plays an important role in tea cold tolerance

Arginine decarboxylase (ADC) is an important enzyme responsible for polyamine (PA) synthesis in plants. In our study, 5 tea varieties were used to investigate the relationship between ADC and cold tolerance in field experiments. A strong and positive correlation was found between cold stress-regulated expression levels of CsADC1 and arginine (Arg) content (R2 > 0.75) in tea mesophyll cells and cold tolerance in 5 tea varieties. An exogenous supply of Arg significantly enhanced cold tolerance. To further clarify the location of CsADC1, the full-length cDNA of the CsADC1 gene was cloned and located in the cell nucleus. Moreover, cold stress significantly promoted the production of MDA in CsADC1-silenced leaves compared with WT plants, which exhibited poor cold tolerance. In contrast, under cold conditions, higher Fv/Fm and lower MDA were detected in CsADC1-overexpressing Arabidopsis than in the WT plants. Furthermore, CsADC1-silenced leaves inhibited the expression levels of the PA metabolism genes CsAIH, CsCPA, CsSPDS, CsSPMS1 and CsSPMS2 under cold stress; thus, significantly lower (p < 0.05) putrescine (Put), spermidine (Spd) and spermine (Spm) content was d etected in CsADC1-silenced tea leaves under cold stress. Taken together, our results indicated that CsADC1, as a positive regulator, played an important role in cold tolerance, which may be due to modulation of polyamine pathways in the cold stress response.

Insulin signaling and antioxidant proteins in adipose tissue explants from dairy cows challenged with hydrogen peroxide are altered by supplementation of arginine or arginine plus methionine.

Arginine (Arg) and methionine (Met) can elicit anti-inflammatory and antioxidant effects in animals. Unlike Met, however, it is unknown if the supply of Arg can impact key aspects of adipose tissue (AT) function in dairy cows. Since Met and Arg metabolism are linked through the synthesis of polyamines, it is also possible that they have a complementary effect on aspects of AT function during a stress challenge. In this experiment, subcutaneous AT was harvested from four lactating multiparous Holstein cows (~27.0kg milk per day, body condition score 3.38±0.23) and used for incubations (4h) with the following: control medium with an "ideal" profile of essential amino acids (IPAA; CTR; Lys:Met 2.9:1), IPAA plus 100 μM H2O2 (HP), H2O2 plus greater Arg supply (HPARG; Lys:Arg 1:1), or H2O2 plus greater Arg and methionine (Met) supply (HPARGMET; Lys:Met 2.5:1 and Lys:Arg 1:1). Western blotting was used to measure abundance of 18 protein targets associated with insulin and AA signaling, nutrient transport, inflammation, and antioxidant response. Reverse transcription polymerase chain reaction (RT-PCR) was used to assess effects on genes associated with Arg metabolism. Among the protein targets measured, although abundance of phosphorylated (p) AKT serine/threonine kinase (P=0.05) and p-mechanistic target of rapamycin (P=0.04) were lowest in HP explants, this effect was attenuated in HPARG and especially HPARGMET compared with CTR. Compared with HP, incubation with HPARG led to upregulation of the AA transporter solute carrier family 1 member 3 (L-glutamate transporter; P=0.03), the reactive oxygen species detoxification-related enzyme glutathione S-transferase mu 1 (GSTM1; P=0.03), and fatty acid synthase (P=0.05). Those effects were accompanied by greater abundance of solute carrier family 2 member 4 (insulin-induced glucose transporter) in explants incubated with HPARG and also HPARGMET (P=0.04). In addition, compared with other treatments, the peak response in abundance of the intracellular energy sensor 5'-prime-AMP-activated protein kinase was detected with HPARGMET (P=0.003). There was no effect of Arg or Arg plus Met on the mRNA abundance of genes associated with Arg metabolism (ARG1, NOS2, AMD1, SMS, and SRM). Overall, supplementation of Arg alone or with Met partially alleviated the negative effects induced by H2O2. More systematic studies need to be conducted to explore the function of Arg supply with or without Met on AT function.

Methionine and Arginine Supply Alters Abundance of Amino Acid, Insulin Signaling, and Glutathione Metabolism-Related Proteins in Bovine Subcutaneous Adipose Explants Challenged with N-Acetyl-d-sphingosine.

Simple SummaryIncreased circulating concentrations of ceramides (Ce) in dairy cows contribute to subcutaneous adipose tissue (SAT) lipolysis and could enhance the risk of developing metabolic disorders. Dietary supply of methionine (Met) or arginine (Arg) alters cellular metabolism in key tissues including SAT. Whether Met or Arg directly affect SAT metabolism when Ce concentrations are elevated is unknown. We propose that Met or Arg could have a beneficial effect within adipose tissue in terms of alleviating potential inflammatory and pro-oxidant effects associated with the transition into lactation.The objective was to perform a proof-of-principle study to evaluate the effects of methionine (Met) and arginine (Arg) supply on protein abundance of amino acid, insulin signaling, and glutathione metabolism-related proteins in subcutaneous adipose tissue (SAT) explants under ceramide (Ce) challenge. SAT from four lactating Holstein cows was incubated with one of the following media: ideal profile of amino acid as the control (IPAA; Lys:Met 2.9:1, Lys:Arg 2:1), increased Met (incMet; Lys:Met 2.5:1), increased Arg (incArg; Lys:Arg 1:1), or incMet plus incArg (Lys:Met 2.5:1 Lys:Arg 1:1) with or without 100 μM exogenous cell-permeable Ce (N-Acetyl-d-sphingosine). Ceramide stimulation downregulated the overall abundance of phosphorylated (p) protein kinase B (AKT), p-mechanistic target of rapamycin (mTOR), and p-eukaryotic elongation factor 2 (eEF2). Without Ce stimulation, increased Met, Arg, or Met + Arg resulted in lower p-mTOR. Compared with control SAT stimulated with Ce, increased Met, Arg, or Met + Arg resulted in greater activation of mTOR (p-mTOR/total mTOR) and AKT (p-AKT/total AKT), with a more pronounced response due to Arg. The greatest protein abundance of glutathione S-transferase Mu 1 (GSTM1) was detected in response to increased Met supply during Ce stimulation. Ceramide stimulation decreased the overall protein abundance of the Na-coupled neutral amino acid transporter SLC38A1 and branched-chain alpha-ketoacid dehydrogenase kinase (BCKDK). However, compared with controls, increased Met or Arg supply attenuated the downregulation of BCKDK induced by Ce. Circulating ceramides might affect amino acid, insulin signaling, and glutathione metabolism in dairy cow adipose tissue. Further in vivo studies are needed to confirm the role of rumen-protected amino acids in regulating bovine adipose function.

L-Arginine Alleviates Hydrogen Peroxide–Induced Oxidative Damage in Ovine Intestinal Epithelial Cells by Regulating Apoptosis, Mitochondrial Function, and Autophagy

Previous studies demonstrated that dietary l-arginine (Arg) alters the equilibrium between reactive oxygen species (ROS) generation and biological defenses to resist oxidant-induced toxicity. Whether supplying Arg can protect ovine intestinal epithelial cells (OIECs) from hydrogen peroxide (H2O2)-induced oxidative damage is unclear. The current study aimed to examine the effect of Arg on mitophagy, mitochondrial dysfunction, and apoptosis induced by H2O2 in OIECs. The OIECs were incubated in Arg-free DMEM supplemented with 100μM Arg (CON) or 350μM Arg (ARG) alone or with 150μM H2O2 (CON+H2O2, ARG+H2O2) for 24h. Cellular apoptosis, mitochondrial function, autophagy, and the related categories of genes and proteins were determined. All data were analyzed by ANOVA using the general linear model procedures of SAS (SAS Institute) for a 2×2 factorial design. Relative to the CON and ARG groups, H2O2 administration resulted in 44.9% and 26.5% lower (P <0.05) cell viability but 34.7% and 61.8% greater (P <0.05) ROS concentration in OIECs, respectively. Compared with the CON and CON+H2O2 groups, Arg supplementation led to 40.7% and 28.8% lower (P <0.05) ROS concentration but 14.9%-49.0% and 29.3%-64.1% greater (P <0.05) mitochondrial membrane potential, relative mitochondrial DNA content, and complex (I-IV) activity in OIECs, respectively. Compared with the CON and CON+H2O2 groups, Arg supplementation led to 33.9%-53.1% and 22.4%-49.1% lower (P <0.05) mRNA abundance of proapoptotic genes, respectively. Relative to the CON and CON+H2O2 groups, Arg supplementation resulted in 33.0%-59.2% and 14.6%-37.7% lower (P <0.05) abundance of proapoptotic, mitophagy, and cytoplasmic cytochrome c protein, respectively. Supply of Arg protects OIECs against H2O2-induced damage partly by improving mitochondrial function and alleviating cellular apoptosis and autophagy.

Leaf arginine spraying improves leaf gas exchange under water deficit and root antioxidant responses during the recovery period

Arginine (Arg) metabolism is associated with many cellular and developmental processes in plants and proline, nitric oxide (NO) and polyamines (PAs) have a wide range of physiological functions in plants, including increased tolerance to environmental stresses. This study aimed to test the hypothesis that Arg spraying would stimulate the synthesis of proline, NO and PAs, reducing the oxidative damage caused by water deficit (WD) and increasing drought tolerance of sugarcane plants. Sugarcane plants were sprayed with water or Arg 1 mM, and subjected to WD by gradual addition of polyethylene glycol (PEG-8000) to the nutrient solution. As references, sugarcane plants were grown in nutrient solution without PEG-8000 and sprayed or not with Arg. Our data indicate that exogenous Arg supply improved leaf gas exchange during water deficit and enhanced the root antioxidative protection of sugarcane plants during the recovery period. Arg supply prevented the proline accumulation induced by water deficit and then the main pathway for proline synthesis is likely through glutamate instead of arginine. Although Arg is a substrate for NO and PAs production, supplying Arg had only slight effects in both NO and PAs levels. The spraying of amino acids capable of reducing the harmful effects of drought, such as Arg, can be an alternative to improve crop growth under field conditions.

Alterations in immune and antioxidant gene networks by gamma-d-glutamyl-meso-diaminopimelic acid in bovine mammary epithelial cells are attenuated by in vitro supply of methionine and arginine

Nucleotide-binding oligomerization domain (NOD)-like receptor 1 (NOD1) is a cytosolic pattern recognition receptor with a crucial role in the innate immune response of cells triggered by the presence of compounds such as gamma-d-glutamyl-meso-diaminopimelic acid (iE-DAP) present in the peptidoglycan of all gram-negative and certain gram-positive bacteria. Methionine (Met) and arginine (Arg) are functional AA with immunomodulatory properties. In the present study, we aimed to assess the effect of increased Met and Arg supply on mRNA abundance of genes associated with innate immune response, antioxidant function, and AA metabolism during iE-DAP challenge in bovine mammary epithelial cells (BMEC). Primary BMEC (n = 4 per treatment) were precultured in modified medium for 12 h with the following AA formulations: ideal profile of AA (control), increased Met supply (incMet), increased Arg supply (incArg), or increased supply of Met plus Arg (incMetArg). Subsequently, cells were challenged with or without iE-DAP (10 μg/mL) for 6 h. Data were analyzed as a 2 × 2 × 2 factorial using the MIXED procedure of SAS 9.4. Greater mRNA abundance of NOD1, the antioxidant enzyme SOD1, and AA transporters (SLC7A1 and SLC3A2) was observed in the incMet cells after iE-DAP stimulation. Although increased Met alone had no effect, incMetArg led to greater abundance of the inflammatory cytokine IL-6, and the antioxidant enzyme GPX1 after iE-DAP stimulation. The increased Arg alone downregulated NOD1 after iE-DAP stimulation, coupled with a downregulation in the AA transporters mRNA abundance (SLC7A1, SLC7A5, SLC3A2, and SLC38A9), and upregulation in GSS and KEAP1 mRNA abundance. Overall, the data indicated that increased supply of both Met and Arg in the culture medium were more effective in modulating the innate immune response and antioxidant capacity of BMEC during in vitro iE-DAP stimulation.

ʟ-Arginine Inhibits Apoptosis of Ovine Intestinal Epithelial Cells through the ʟ-Arginine–Nitric Oxide Pathway

In nonruminants, many of the biological roles of l-arginine (Arg) at the intestinal level are mediated through the Arg-nitric oxide (Arg-NO) pathway. Whether the Arg-NO pathway is involved in controlling the immune response and viability in ovine intestinal epithelial cells (IOECs) is unclear. The current study aimed to examine the role of the Arg-NO pathway in apoptosis, antioxidant capacity, and mitochondrial function of IOECs. The IOECs were incubated in Arg-free DMEM supplemented with 150μM Arg (CON) or 300μM Arg (ARG) alone or with 350μM Nw-nitro-l-arginine methyl ester hydrochloride (l-NAME) (CON+NAME, ARG+NAME) for 24h. The reactive oxygen species (ROS) concentration, antioxidant capacity, and cell apoptotic percentage were determined. Arg supplementation decreased (P <0.05) the ROS concentration (38.9% and 22.7%) and apoptotic cell percentage (57.2% and 54.8%) relative to the CON and CON+NAME groups, respectively. Relative to the CON and ARG treatments, the l-NAME administration decreased (P <0.05) the mRNA abundance of superoxide dismutase 2 (32% and 21.3%, respectively) and epithelial NO synthase (36% and 29.1%, respectively). Arg supplementation decreased (P <0.05) the protein abundance of apoptosis antigen 1 (FAS) (52.0% and 43.9%) but increased (P <0.05) those of nuclear respiratory factor 1 (31.3% and 22.9%) and inducible NO synthase (35.2% and 41.8%) relative to the CON and CON+NAME groups, respectively. The inhibition of apoptosis in IOECs due to the increased supply of Arg is associated with the mitochondria- and FAS-dependent pathways through the activity of the Arg-NO pathway. The findings help elucidate the role of the Arg-NO pathway in IOEC growth and apoptosis.

Chloride and amino acids are associated with K+-alleviated drought stress in tea (Camellia sinesis).

Drought is one of the main limiting factors affecting tea plant yield and quality. Previous studies have reported that K+ (potassium) application significantly alleviated drought-induced damage in tea plants. However, the intrinsic mechanisms underlying K+-alleviated drought stress are still obscure. In our study, two contrasting varieties, Taicha12 (drought tolerant) and Fuyun6 (drought sensitive), were used to investigate the intrinsic mechanisms behind K+-alleviated drought stress in tea plants. In the present study, we compared with the case of tea plants under drought: higher water and chlorophyll contents were found in drought-stressed tea plants with an external K+ supply, confirming the role of externally supplied K+ in mitigating drought stress. We also found that an adequate K+ supply promoted Cl- accumulation in the mesophyll of Taicha12 (drought tolerant) over that of in Fuyun6 (drought sensitive). Moreover, Gly, Cys, Lys and Arg were not detected in Fuyun6 under 'Drought' or 'Drought + K+' conditions. Results showed that an exogenous supply of Arg and Val significantly alleviated drought-induced damage in Fuyun6, suggesting their role in K+-alleviated drought stress in tea plants. Collectively, our results show that chloride and amino acids are important components associated with K+-alleviated drought stress in tea plants.

Methionine and arginine supplementation alter inflammatory and oxidative stress responses during lipopolysaccharide challenge in bovine mammary epithelial cells in vitro

Mastitis, inflammation of the udder, is one of the most common diseases hampering milk yield of dairy cows. Methionine (Met) and arginine (Arg) are key nutrients with potential to regulate inflammation and oxidative stress. The aim of this study was to evaluate the effect of increased supply of Met and Arg on mRNA and protein abundance associated with innate immune response and redox balance during lipopolysaccharide (LPS) stimulation in primary bovine mammary epithelial cells (BMEC). Primary BMEC (n = 4 replicates per treatment) were pre-incubated for 12 h in media with the following amino acid combinations: ideal profile of amino acids (control; Con), increased Met supply (incMet), increased Arg supply (incArg), and increased supply of Met and Arg (incMetArg). Subsequently, cells were challenged with or without LPS (1 µg/mL) and incubated for 6 h. Data were analyzed as a 2 × 2 × 2 factorial using the MIXED procedure of SAS 9.4 (SAS Institute Inc., Cary, NC). The downregulation of SLC36A1 and SLC7A1 mRNA abundance induced by LPS was attenuated in the incArg cultures. Although challenge with LPS led to lower abundance of proteins related to the antioxidant response (NFE2L2, NQO1, GPX1), lower levels of ATG7, and lower mRNA abundance of GPX3, we found little effect in cultures with incMet or incArg. Cultures with incMet, incArg, or incMetArg led to attenuation of the upregulation of SOD2 and NOS2 induced by LPS. Abundance of phosphorylated p65 (RELA) was greater after LPS stimulation, but the response was attenuated in cultures with incMet. The greater ratio of pRELA to total RELA in responses to LPS was also attenuated in cultures with incMetArg. The greater mRNA abundance of the proinflammatory cytokine IL1B induced by LPS was attenuated in cultures with incMet, and the same trend induced by LPS on CXCL2 was also alleviated in cultures with incArg. Overall, the data suggest that greater supply of Met and Arg alleviated the proinflammatory responses triggered by LPS through controlling the abundance of proinflammatory cytokines and chemokines and activity of NF-κB. Little benefit on oxidative stress induced by LPS challenge in BMEC was detected with greater supply of Met and Arg.

Jugular arginine supplementation increases lactation performance and nitrogen utilization efficiency in lactating dairy cows

BackgroundEnhancing the post-ruminal supply of arginine (Arg), a semi-essential amino acid (AA), elicits positive effects on milk production. Our objective was to determine the effects of Arg infusion on milk production parameters and aspects of nitrogen (N) absorption and utilization in lactating dairy cows. Six lactating Chinese Holstein cows of similar body weight (508 ± 14 kg), body condition score (3.0 ± 0), parity (4.0 ± 0), milk yield (30.6 ± 1.8 kg) and days in milk (20 ± 2 d) were randomly assigned to 3 treatments in a replicated 3 × 3 Latin square design with 21 d for each period (1 week for infusion and 2 weeks for washout). Treatments were 1) Control: saline; 2) Arg group: saline + 9.42 g/L L-Arg; 3) Alanine (Ala) group: saline + 19.31 g/L L-Ala (iso-nitrogenous to the Arg group). Milk production and composition, dry matter intake, apparent absorption of N, profiles of amino acids (AA) in blood, urea N in urine, milk, and blood, and gene expression of AA transporters were determined.ResultsCompared with the Control or Ala group, the infusion of Arg led to greater expression of AA transporters (SLC7A2 and SLC7A8) and apparent uptake of free AA in the mammary gland, and was accompanied by greater milk yield, milk protein yield and milk efficiency (calculated by dividing milk yield over feed intake), together with lower concentration of urea N [regarded as an indicator of N utilization efficiency (NUE)] in blood and milk. Furthermore, in the cows infused with Arg, the NUE was higher and the concentration of urea N in urine was lower than those in the Ala group, although no differences were detected in NUE and urea N in urine between the Control and Arg group. The infusion of Ala had no effect on those indices compared with the Control.ConclusionsOverall, enhancing the post-ruminal supply of Arg via the jugular vein had a positive effect on the synthesis of milk protein at least in part by increasing gene expression of some AA transporters and uptake of free AA by mammary gland.

Enhanced supply of methionine or arginine alters mechanistic target of rapamycin signaling proteins, messenger RNA, and microRNA abundance in heat-stressed bovine mammary epithelial cells in vitro

Heat stress (HS) causes reductions in milk production, but it is unclear whether this effect is due to reduced number or functional capacity (or both) of mammary cells. Methionine supplementation improves milk protein, whereas Arg is taken up in excess by mammary cells to produce energy and nonessential AA that can be incorporated into milk protein. To evaluate molecular mechanisms by which mammary functional capacity is affected by HS and Met or Arg, mammary alveolar (MAC-T) cells were incubated at thermal-neutral (37°C) or HS (42°C) temperatures. Treatments were optimal AA profiles (control; Lys:Met = 2.9:1.0; Lys:Arg = 2.1:1.0), control plus Met (Lys:Met = 2.5:1.0), or control plus Arg (Lys:Arg = 1.0:1.0). After incubation for 6 h, cells were harvested and RNA and protein were extracted for quantitative real-time PCR and Western blotting. Protein abundance of mechanistic target of rapamycin (MTOR), eukaryotic initiation factor 2a, serine-threonine protein kinase (AKT), 4E binding protein 1 (EIF4EBP1), and phosphorylated EIF4EBP1 was lower during HS. The lower phosphorylated EIF4EBP1 with HS would diminish translation initiation and reduce protein synthesis. Both Met and Arg had no effect on MTOR proteins, but the phosphorylated EIF4EBP1 decreased by AA, especially Arg. Additionally, Met but not Arg decreased the abundance of phosphorylated eukaryotic elongation factor 2, which could be positive for protein synthesis. Although HS upregulated the heat shock protein HSPA1A, the apoptotic gene BAX, and the translation inhibitor EIF4EBP1, the mRNA abundance of PPARG, FASN, ACACA (lipogenesis), and BCL2L1 (antiapoptotic) decreased. Greater supply of Met or Arg reversed most of the effects of HS occurring at the mRNA level and upregulated the abundance of HSPA1A. In addition, compared with the control, supply of Met or Arg upregulated genes related to transcription and translation (MAPK1, MTOR, SREBF1, RPS6KB1, JAK2), insulin signaling (AKT2, IRS1), AA transport (SLC1A5, SLC7A1), and cell proliferation (MKI67). Upregulation of microRNA related to cell growth arrest and apoptosis (miR-34a, miR-92a, miR-99, and miR-184) and oxidative stress (miR-141 and miR-200a) coupled with downregulation of fat synthesis-related microRNA (miR-27ab and miR-221) were detected with HS. Results suggest that HS has a direct negative effect on synthesis of protein and fat, mediated in part by coordinated changes in mRNA, microRNA, and protein abundance of key networks. The positive responses with Met and Arg raise the possibility that supplementation with these AA during HS might have a positive effect on mammary metabolism.

Jugular infusion of arginine has a positive effect on antioxidant mechanisms in lactating dairy cows challenged intravenously with lipopolysaccharide1.

The main purpose of this work was to evaluate the effects of jugular l-arginine infusion on antioxidant mechanisms in lactating dairy cows challenged intravenously with lipopolysaccharide (LPS). Eight multiparous Holstein cows (609 ± 32 kg) at midlactation were randomly assigned to 5-d jugular infusions of Control (saline), Arginine (Arg, 18 g/d), LPS (0.2 μg/kg BW per day), and LPS + Arginine (0.2 μg/kg BW per day of LPS and 18 g/d of Arg) in a replicated 4 × 4 Latin square design with 4 infusion periods separated by 10-d. Jugular solutions of saline, Arg, LPS, and LPS + Arg were continuously infused using peristaltic pumps for approximately 6 h/d. Jugular vein serum samples were obtained on the last day of each infusion period before infusion (0 h) and at 3- and 6-h postinfusion. Compared with LPS treatment, Arg infusion increased the total antioxidant capacity and activity of glutathione peroxidase, but decreased malondialdehyde concentration (P < 0.05). The concentration of nitric oxide in serum and the activity of nitric oxide synthase were greater in LPS treatment compared with saline and Arg (P < 0.05). The Arg treatment significantly increased the serum insulin concentration at 3-h postinfusion compared with the saline treatment (P < 0.05), and that of LPS and LPS + Arg treatments were in between Arg and LPS treatments. No treatment effect was observed on the activities of superoxide dismutase and catalase (P > 0.05). In conclusion, enhancing the supply of Arg during an inflammatory challenge enhances antioxidant mechanisms in lactating dairy cows.

Metabolic and clinical response to Escherichia coli lipopolysaccharide in layer pullets of different genetic backgrounds supplied with graded dietary L-arginine

L-arginine (Arg) is an essential amino acid in birds that plays a decisive role in avian protein synthesis and immune response. Effects of graded dietary Arg supply on metabolic and clinical response to Escherichia coli lipopolysaccharide (LPS) were studied over 48 hours after a single intramuscular LPS injection in 18-week-old genetically diverse purebred pullets. LPS induced a genotype-specific fever response within 4 hours post injectionem. Whereas brown genotypes showed an initial hypothermia followed by longer-lasting moderate hyperthermia, white genotypes exhibited a biphasic hyperthermia without initial hypothermia. Furthermore, within 2 hours after LPS injection, sickness behavior characterized by lethargy, anorexia, intensified respiration, and ruffled feathers appeared, persisted for 3 to 5 hours and recovered 12hours post injectionem. The varying grades of Arg did not alter the examined traits named above, whereas insufficient Arg reduced body growth and increased relative weights of liver and pancreas significantly. At 48hours post injectionem, increased relative weights of liver and spleen were also found in LPS treated pullets, whereas LPS decreased those of pancreas, bursa, thymus, and cecal tonsils. Moreover, LPS lowered the sum of plasma amino acids and decreased plasma concentrations of Arg, citrulline, glutamate, methionine, ornithine, phenylalanine, proline, tryptophan, and tyrosine, and increased those of aspartate, glutamine, lysine, 1- and 3-methyl-histidine. Elevating concentrations of dietary Arg led to increasing plasma concentrations of Arg, citrulline, ornithine, and 3-methyl-histidine subsequently. As quantitative expression of LPS-induced anorexia, proteolysis, and the following changes in plasma amino acids, pullets showed a significant decrease of feed and nitrogen intake and catabolic metabolism characterized by negative nitrogen balance and body weight loss in the first 24 hours post injectionem. Pullets recovered from the challenge within the second 24 hours post injectionem and changed to anabolism with re-increased feed and nitrogen intake, positive nitrogen retention, and weight gain. To conclude, present results confirmed that LPS induced numerous metabolic and physiological changes in pullet's genotypes, whereas dietary Arg affected the examined traits only slightly.

Effects of Graded Dietary L-arginine Supply on Organ Growth in Four Genetically Diverse Layer Lines during Rearing Period.

Little information has been available about the influence of genetic background and dietary L-arginine (Arg) supply on organ growth of chickens. Therefore, the present study examined the effects of a graded ad libitum Arg supply providing 70, 100 and 200% of recommended Arg concentration on organ growth of female chickens from hatch to 18 weeks of age. The chickens derived from four layer lines of different phylogeny (white vs. brown) and laying performance (high vs. low). Based on residual feed and absolute body and organ weights recorded in six-week-intervals, feed consumption, changes of relative organ weights and allometric organ growth were compared between experimental groups.Surplus Arg caused higher feed intake than insufficient Arg (p<0.01) that induced growth depression in turn (p <0.05). During the entire trial chicken's heart, gizzard and liver decreased relatively to their body growth (p<0.001) and showed strong positive correlations among each other. On the contrary, proportions of pancreas and lymphoid organs increased until week 12 (p<0.001) and correlated positively among each other. Due to their opposite growth behaviour (p<0.001), internal organs were assigned to two separate groups. Furthermore, insufficient Arg induced larger proportions of bursa, gizzard and liver compared with a higher Arg supply (p<0.05). In contrast to less Arg containing diets, surplus Arg decreased relative spleen weights (p<0.01). The overall allometric evaluation of data indicated a precocious development of heart, liver, gizzard, pancreas and bursa independent of chicken's genetic and nutritional background. However, insufficient Arg retarded the maturation of spleen and thymus compared with an adequate Arg supply.In conclusion, the present results emphasised the essential function of Arg in layer performance, and indicated different sensitivities of internal organs rather to chicken's dietary Arg supply than to their genetic background.

Arginine production &amp; nitric oxide synthesis in pregnancy, a study in Jamaican, American and Indian women

Arginine (arg) supply is critical for a successful pregnancy because of its roles in protein, nitric oxide (NO) and creatine syntheses and in cell growth and differentiation. NO is especially important for vascular expansion in pregnancy and a deficiency of arg supply could underlie the high prevalence of low birth weight (LBW) neonates in Indian women and in adolescent girls. Stable isotope tracers were used to measure arg flux and NO synthesis in pregnant American, Indian and Jamaican women and teenagers. Gestation Jamaica India United States Weeks Adult N=8 Teen N=8 Norm. BMI N=10 Low BMI N=10 Adult N=6 Arg Flux (μmol/kg/h) 13 108±6a 107±6a 50±2b 63±3b 20 108±5a 28 114±12a 82±7a 45±2b 50±2b 36–39 82±3 Post‐partum 73±6 Values are Mean±SEM; versus postpartum value, P&lt;0.01 lower than Jamaican and American values, P&lt;0.01 Except for normal BMI Indian women, NO synthesis was not different among groups at trimesters 1 and 3. Pregnant Indian women produced arg at a slower rate compared to all others. This slower arg flux was associated with slower NO synthesis in normal BMI, but not in low BMI Indian women. There were significant correlations between birth weight and arg flux at trimester 1 (r=0.54, P&lt;0.01) and trimester 3 (r= 0.53, P&lt;0.01), indicating a strong association between decreased arg flux and LBW. Not surprisingly, the Indian women delivered 45% LBW babies compared to 19% for Jamaicans.Grant Funding Source: USDA/ARS

The ArabidopsisTUMOR PRONE5Gene Encodes an Acetylornithine Aminotransferase Required for Arginine Biosynthesis and Root Meristem Maintenance in Blue Light

Arginine is an essential amino acid necessary for protein synthesis and is also a nitrogen storage compound. The genes encoding the enzymes of arginine biosynthesis in plants are not well characterized and have mainly been predicted from homologies to bacterial and fungal genes. We report the cloning and characterization of the TUMOR PRONE5 (TUP5) gene of Arabidopsis (Arabidopsis thaliana) encoding an acetylornithine aminotransferase (ACOAT), catalyzing the fourth step of arginine biosynthesis. The free arginine content was strongly reduced in the chemically induced recessive mutant tup5-1, root growth was restored by supplementation with arginine and its metabolic precursors, and a yeast (Saccharomyces cerevisiae) ACOAT mutant was complemented by TUP5. Two null alleles of TUP5 caused a reduced viability of gametes and embryo lethality, possibly caused by insufficient Arg supply from maternal tissue. TUP5 expression is positively regulated by light, and a TUP5-green fluorescent protein was localized in chloroplasts. tup5-1 has a unique light-dependent short root phenotype. Roots of light-grown tup5-1 seedlings switch from indeterminate growth to determinate growth with arresting cell production and an exhausted root apical meristem. The inhibitory activity was specific for blue light, and the inhibiting light was perceived by the root. Thus, tup5-1 reveals a novel role of amino acids and blue light in regulating root meristem function.

Milk protein responses in dairy cows to changes in postruminal supplies of arginine, isoleucine, and valine

An ideal profile of essential AA (EAA) can improve the efficiency of metabolizable protein (or PDIE, the equivalent in the INRA feeding system) utilization in dairy cows. Compared with other EAA, existing recommendations for the requirements of Arg, Ile, and Val are few and inconsistent. Four multiparous Holstein dairy cows at 22±6 wk of lactation received 4 treatments (duodenal infusions of 445±22.4g/d of an EAA mixture complementing a low-protein diet in a 4×4 Latin square design with a period length of 1 wk). The control treatment provided a balanced supply (in % of PDIE) of 5.1% Arg, 5.2% Ile, and 5.9% Val, whereas in the 3 subsequent treatments of −Arg, −Ile, and −Val, the concentrations of these 3 EAA were reduced to 3.5, 4.1, and 4.5%, respectively. All treatments were made isonitrogenous and were balanced to provide 7 other EAA (Lys, Met, His, Leu, Phe, Thr, and Trp), according to the recommendations described in the literature. Combined, the diet and the infusions provided 14.3±0.1% crude protein on a dry matter basis, and 66.0±1.2g of PDIE/Mcal of net energy for lactation. Neither dry matter intake (19.2kg/d) nor milk yield (30.4±0.4kg/d) was affected by treatments. The −Arg and −Ile treatments did not modify milk protein synthesis or the efficiency of N utilization. However, the −Val treatment decreased milk protein content by 4.9% and milk crude protein content by 4.3%, and tended to decrease the efficiency of N use for milk protein yield by 3.7% (compared with the control). These effects of Val were related to a decrease in the plasma concentration of Val as well as a trend toward decreasing plasma concentrations of Met, His, and the sum of all EAA and nonessential AA in the −Val treatment, which indicates a different utilization of all AA in response to the Val deficit. The deletion of Ile, compared with the deletion of Val, tended to decrease the milk protein-to-fat ratio by 3.8%. In conclusion, the supply of Arg at 3.5% of PDIE was not limiting for milk protein synthesis. The slight effect on the milk protein-to-fat ratio caused by decreasing the supply of Ile suggests a need to reevaluate the Ile requirement more precisely. A low Val supply could be limiting for milk protein synthesis, provided that the requirements of Lys, Met, and His are met.

Re-evaluation of Arginine Requirements for Broilers Exposed to Hypobaric Condition during the 3-to 6-week Period

In order to estimate arginine (Arg) requirements of male broilers (Ross 308) during the 21-to 42-day period and exposed to hypobaric condition, six diets (200 g/kg CP and 13.4 MJ ME/kg) with graded levels of Arg (8.8 to 14.3 g/kg) were allocated to four pens of twelve birds each. Body weight gain, feed:gain, breast meat yield, plasma nitric oxide (NO) concentration, and right to total ventricular weight ratio (RV/TV) were determined as response criteria. Responses to Arg supply were nonlinear and attained plateau values (ymax) within the studied range of Arg supply. The estimated Arg requirements for maximal body weight gain and optimal feed:gain during the 21 days under study were 12.4, and 12.2 g/kg of diet, respectively. The estimated Arg requirement for maximizing breast meat yield was 12.6 g/kg of diet. Based on the response in plasma NO and RV/TV, the estimated requirements were 13.0, and 13.2 g/kg of diet, respectively. Data obtained for the individual factors clearly indicate that the NRC recommendations for Arg are not sufficient for maximizing body weight gain, optimizing feed:gain and preventing the onset of pulmonary hypertension in broiler chickens exposed to hypobaric condition. Data may be used for future modeling of broilers’ Arg requirements.

Deletion of arginine from an abomasal infusion of amino acids does not decrease milk protein yield in Holstein cows

This study was undertaken to determine if a limited supply of Arg would alter milk and milk protein yields, as well as mammary uptake of AA and energetic substrates. Six lactating Holstein cows (199±5 d in milk) were used in a replicated 3 × 3 Latin square balanced for residual effects with 14-d periods. The diet was formulated to supply 100% of the National Research Council net energy requirement and 72% of the metabolizable protein requirement. The treatments were randomly distributed as abomasal infusions of (1) water (CTL), (2) a mixture of essential AA (EAA) excluding Arg (ARG−), or (3) a mixture of EAA including Arg (ARG+). The profile of EAA in the infusates was the same as that found in casein with the exception that methionine was increased to maintain a 3:1 ratio of digestible lysine:methionine (total dietary+infusion). Milk protein yield was increased by the ARG+ compared with the CTL treatment and deletion of Arg in the infusate (ARG−) did not impair this response. Deletion of Arg from the EAA mixture decreased the mammary uptake of Arg relative to that of the CTL treatment, and although the uptake:output ratio decreased from 2.52 (ARG+) to 2.12 (ARG−), it was still largely in excess of Arg secretion in milk protein. Otherwise, Arg deletion did not affect any of the measured parameters (no significant difference between ARG− and ARG+) except Arg and urea arterial concentrations. In support of the increased yields of milk protein and lactose, mammary uptake of the group 2 AA (Ile, Leu, Lys, and Val) increased and the uptake:output ratio tended to increase from 1.04 to 1.23. The mammary uptake:milk protein output ratio was not different from 1 and not different among treatments for the group 1 AA (His, Met, Phe+Tyr, Trp). Mammary uptake of energetic substrates did not vary across treatments, although milk lactose yield increased with the ARG+ treatment relative to CTL. These results indicate that deletion of Arg has minimal effects on milk and milk component yields when the remaining EAA are supplied in sufficient amounts despite decreased mammary Arg uptake and that group 2 AA seem to be involved in the mammary gland to support the lactose yield response to EAA infusion.

Arginine metabolism in uricotelic species

Due to the lack of a complete urea cycle, uricotelic species, such as broilers, are not able to synthesize de novo arginine (Arg), thus depending exclusively on dietary Arg. High levels of dietary lysine (Lys) increase the demand for Arg because of the antagonistic relationship between these amino acids. The Arg-Lys antagonism promotes an expressive increase in the renal Arg activity and consequently induces the degradation of Arg and the decrease in the activity of glycine amidinotransferase, an enzyme that uses Arg in the synthesis of muscle creatin. Arg is considered an important modulator of immunological and physiological processes. The degradation of Arg produces ornithine, a precursor of polyamines that are key to cell division, DNA synthesis, and cell cycle regulation. Arg participates in the synthesis of nitric oxide (NO), a highly reactive free radical in cells and membranes and participates in several cell processes, including in neurotransmission and immune response. Arg is also considered a potent secretagogue of insulin, growth hormone, and IGF-I in the blood stream. Exclusively vegetarian diets may not provide an adequate supply of Arg, which is required for maximum production and for the immune system of current broiler lineages.