Role Of AA Research Articles

162 The role of functional amino acids in optimizing nutrition and health

Abstract The ability of a diet or an individual protein-containing ingredient to satisfy the indispensable amino acid (IAA) requirements of an individual is a reflection of protein quality. In human nutrition, the concept of PQ is well recognized and widely applied to facilitate guidance on the extensive range of food items we consume. In the pet food industry, the concept of PQ is gaining recognition as a way in which to identify ideal candidate ingredients for diet formulation and our laboratory has recently completed a large data base of PQ estimates of typical ingredients used in the pet food industry to compliment the emerging PQ ingredient data. Our laboratory has also used more advanced methodologies, specifically the IAAO technique, to measure the dietary Phe, Trp, Met, Thr, and Lys requirements for adult dogs of small, medium and large breed dogs. The role of AA beyond support of protein turnover (adults) or protein deposition (growth) is being explored, such as the role of certain AA in behavior, immune function and inflammation. For example, the ratio of tryptophan to the large neutral amino acids of 0.75:1.0 in contrast to 0.46:1.0 resulted in better indices of gut health and may reduce agonistic behaviors both of which are underpinned by improved serotonergic status. The role of the sulfur AA in the development of dilated cardiomyopathy further highlights the role of IAA as sources for secondary metabolites, such as taurine and glutathione in supporting animal health. Indeed, many AA are becoming referred to as functional AA and the requirement of these AA may differ in healthy and challenged animals and deserve attention in dog and cat nutrition as well. Overall, the pattern of AA that defines the requirement of healthy dogs and cats, may not be the pattern that would support the animal under challenging conditions. Research into supporting different physiological challenges and how these may affect amino acid requirements is warranted.

Influence of Rheum taxa and harvesting date on the content of L-ascorbic acid and oxalic acid in the climatic conditions of South Moravia (Czech Republic)

ABSTRACT Rhubarb (Rheum L.) is a well-known medicinal and culinary plant. Apart from its rich nutritional value, rhubarb contains a higher concentration of oxalates. In this study, the content of L-ascorbic acid (AA) and oxalic acid (OA) within three rhubarb species (Rheum rhabarbarum, R. rhaponticum and R. palmatum × wittrockii) differentiated to 16 accessions in a gene bank rhubarb collection (Lednice, Czech Republic) in the condition of conventional production in the South Moravia region during the harvesting period was evaluated. While L-ascorbic acid is essential in human nutrition, oxalic acid is considered toxic, and high doses may cause serious health issues. AA and OA content, the morphology evaluation and ISSR (inter simple sequence repeats)-based genetic analysis were performed. The results of this study confirm the significant influence of taxonomy and harvesting time on the content of AA in Rheum accessions. The content of AA was determined from 6 mg · 100 g-1 to 10 g · 100 g-1 fresh weight (FW) at the beginning of the harvesting season (May) up to 25 mg · 100 g-1 FW at the end of the harvesting period. The content of OA strongly varied from 300 mg · 100 g-1 to 1800 mg · 100 g-1 FW. Regarding the antinutrient character of oxalate, the optimal harvest period of this region was estimated to be from May to early June, when the OA content was the lowest. The role of AA as a precursor of oxalate formation in rhubarb was not affirmed by the results of this study.

Study of leptin gene polymorphism and leptin serum level in alopecia areata patients

ABSTRACT Leptin, produced by adipocytes, regulates metabolism, hunger, and immune response. The inflammatory role of leptin has been linked to autoimmune diseases. To assess leptin gene polymorphism and serum level in alopecia areata and their relation to metabolic syndrome (MS). This case-control study was conducted on 100 alopecia areata patients (50 with MS and 50 without MS) and 50 age- and gender-matched controls. Leptin gene polymorphism and serum level were assessed through the use of PCR and ELISA, respectively. GG genotype was the highest in AA with MS (54%), lower in AA without MS (42%), and the lowest in controls (20%). G allele was more expressed in cases, than in controls (P < .001). The serum leptin level was the highest in AA with MS, lower in AA without MS, and the lowest in controls (P value = 0.001). Leptin level was significantly higher in GG polymorphism than AG and AA. Leptin gene polymorphism (GG genotype) and serum level appear to play a significant role in AA. Absent difference regarding leptin gene polymorphism and MS might indicate a separate inflammatory role of leptin or the future risk of MS development in AA patients.

Ascorbic Acid Reduces Neurotransmission, Synaptic Plasticity, and Spontaneous Hippocampal Rhythms in In Vitro Slices.

Ascorbic acid (AA; a.k.a. vitamin C) is well known for its cellular protection in environments of high oxidative stress. Even though physiological concentrations of AA in the brain are significant (0.2–10 mM), surprisingly little is known concerning the role of AA in synaptic neurotransmission under normal, non-disease state conditions. Here, we examined AA effects on neurotransmission, plasticity and spontaneous network activity (i.e., sharp waves and high frequency oscillations; SPW-HFOs), at the synapse between area 3 and 1 of the hippocampal cornu ammonis region (CA3 and CA1) using an extracellular multi-electrode array in in vitro mouse hippocampal slices. We found that AA decreased evoked field potentials (fEPSPs, IC50 = 0.64 mM) without affecting V50s or paired pulse facilitation indicating normal neurotransmitter release mechanisms. AA decreased presynaptic fiber volleys but did not change fiber volley-to-fEPSP coupling, suggesting reduced fEPSPs resulted from decreased fiber volleys. Inhibitory effects were also observed in CA1 stratum pyramidale where greater fEPSPs were required for population spikes in the presence of AA suggesting an impact on the intrinsic excitability of neurons. Other forms of synaptic plasticity and correlates of memory (i.e., short- and long-term potentiation) were also significantly reduced by AA as was the incidence of spontaneous SPW-HFOs. AA decreased SPW amplitude with a similar IC50 as fEPSPs (0.65 mM). Overall, these results indicate that under normal conditions AA significantly regulates neurotransmission, plasticity, and network activity by limiting excitability. Thus, AA may participate in refinement of signal processing and memory formation, as well as protecting against pathologic excitability.

Cycle Network Model of Prostaglandin H Synthase-1.

The kinetic model of Prostaglandin H Synthase-1 (PGHS-1) was developed to investigate its complex network kinetics and non-steroidal anti-inflammatory drugs (NSAIDs) efficacy in different in vitro and in vivo conditions. To correctly describe the complex mechanism of PGHS-1 catalysis, we developed a microscopic approach to modelling of intricate network dynamics of 35 intraenzyme reactions among 24 intermediate states of the enzyme. The developed model quantitatively describes interconnection between cyclooxygenase and peroxidase enzyme activities; substrate (arachidonic acid, AA) and reducing cosubstrate competitive consumption; enzyme self-inactivation; autocatalytic role of AA; enzyme activation threshold; and synthesis of intermediate prostaglandin G2 (PGG2) and final prostaglandin H2 (PGH2) products under wide experimental conditions. In the paper, we provide a detailed description of the enzyme catalytic cycle, model calibration based on a series of in vitro kinetic data, and model validation using experimental data on the regulatory properties of PGHS-1. The validated model of PGHS-1 with a unified set of kinetic parameters is applicable for in silico screening and prediction of the inhibition effects of NSAIDs and their combination on the balance of pro-thrombotic (thromboxane) and anti-thrombotic (prostacyclin) prostaglandin biosynthesis in platelets and endothelial cells expressing PGHS-1.

Effect of chronic administration of arachidonic acid on the performance of learning and memory in aged rats.

BackgroundArachidonic acid (AA, C20:4, ω-6) is a ω-6 polyunsaturated fatty acid (PUFA) and plays diverse roles in cell signaling. Numerous reports on the effects of ω-3 PUFAs, such as docosahexaenoic acid (DHA, C22:6, ω-3) and eicosapentaenoic acid (EPA, C20:5, ω-3) on learning and memory impairments of rats are available, however, the role of AA on brain cognition is largely unknown.ObjectiveIn this study, our aim was to investigate the effect of oral administration of AA on spatial memory-related learning ability in aged (100 weeks) male rats.DesignOne group was per orally administered 240 mg/kg per day AA oil and the other group was administered the similar volume of control oil. Five weeks after the start of the administration, rats were tested with the partially baited eight-arm radial maze to evaluate two types of spatial memory-related learning ability displayed by reference memory errors (RMEs) and working memory errors (WMEs). Also, the time required to complete the task was recorded. The levels of lipid peroxide (LPO) and reactive oxygen species (ROS) were measured, as an indicator oxidative stress in the plasma and brain corticohippocampal brain tissues.ResultsThe scores of RMEs and WMEs, which are analogous to long-term and short-term memory, respectively, were not affected, however, the trial time was shorter in the AA-administered rats than that of the controls. AA also significantly increased the degree of oxidative stress both in the plasma and corticohippocampal brain tissues.ConclusionsOur results suggest that though AA deposition in the corticohippocampal tissues of senescent rats caused a faster performance activity, which is reminiscent to hyperactive behavior of animals, the spatial learning ability-related memory of the rats, however, was not improved.

Relationships between spawn quality and biochemical composition of eggs and hatchlings of Octopus vulgaris under different parental diets

Abstract Three frozen mono-diets (sardine, crab and squid) were supplied to Octopus vulgaris broodstocks, and their effects on the spawn quality and biochemical composition of eggs and hatchlings were studied. Squid and crab diets achieved superior spawn quality, producing in general significantly larger eggs, as compared to sardine diet. Similar differences were also observed in the biometric parameters of hatchlings (ventral and dorsal mantle lengths and dry weight) as well as in the survival of fasted hatchling which were greater in the squid and crab groups with respect to sardine treatment. On the other side, a strong and significant relationship between the mentioned biometrical measures and hatchlings survival was found, suggesting that eggs and hatchlings early biometrical measures can be utilized as a predictor for larval viability. Statistical techniques as multivariate and correlation analyses were used to distinguish dietary groups based on protein content and lipid and fatty acid composition of achieved eggs and hatchlings as well as to relate this composition with spawn quality parameters. The analyses allowed to discriminate the nutrient composition of the early stages which was also found to be significantly correlated to the differences in the spawn quality of the different dietary groups, thereby underlining the importance of the protein content, and lipid classes like phosphatidylethanolamine, phosphatidylcholine, cholesterol and triacylglycerol, as well as docosahexaenoic (22:6n-3) and eicosapentaenoic (20:5n-3) fatty acids in the reproduction of O. vulgaris . Statement of Relevance It has been demonstrated that biochemical composition of the broodstock diet is a major determinant of successful reproduction and offspring survival in teleost fish (Watanabe & Vasallo-Agius, 2003; Bobe and Labbe, 2009). For Octopus vulgaris , our data suggest that the broodstock diet influenced the protein content and lipid composition of eggs and hatchlings, and these nutrients are related to the differences found in the spawn quality. A strong and significant relationship between the measured biometrical parameters and hatchlings survival was also found, suggesting that eggs and hatchlings early biometrical measures can be utilized as a predictor for larval viability. On the other side, the utilization of nutrients during the embryo development can also be seen as an indicator of the nutritional requirements during the early stages of development and be useful for a future advance in the formulation of paralarvae artificial diets. Our results pointed to an embryo catabolism mainly based on proteins, as previously suggested (Lee, 1994; Villanueva and Norman, 2008). Data also suggest that triacylglycerol, sterol ester and phosphatidylcholine were specifically catabolized for energy and/or used to de novo synthesize lipid classes such as PS or PE. Within fatty acids, we found that arachidonic acid was strongly reduced (50–51%) during embryonic development. Further studies on the particular role of AA and the n–3 HUFA (mainly EPA and DHA) for early stages of O. vulgaris are needed, specially taking into account that these FAs are essential for this species (Monroig et al., 2012a,b).

Boundary layer stability and Arctic climate change: a feedback study using EC-Earth

Amplified Arctic warming is one of the key features of climate change. It is evident in observations as well as in climate model simulations. Usually referred to as Arctic amplification, it is generally recognized that the surface albedo feedback governs the response. However, a number of feedback mechanisms play a role in AA, of which those related to the prevalent near-surface inversion have received relatively little attention. Here we investigate the role of the near-surface thermal inversion, which is caused by radiative surface cooling in autumn and winter, on Arctic warming. We employ idealized climate change experiments using the climate model EC-Earth together with ERA-Interim reanalysis data to show that boundary-layer mixing governs the efficiency by which the surface warming signal is ‘diluted’ to higher levels. Reduced vertical mixing, as in the stably stratified inversion layer in Arctic winter, thus amplifies surface warming. Modelling results suggest that both shortwave—through the (seasonal) interaction with the sea ice feedback—and longwave feedbacks are affected by boundary-layer mixing, both in the Arctic and globally, with the effect on the shortwave feedback dominating. The amplifying effect will decrease, however, with climate warming because the surface inversion becomes progressively weaker. We estimate that the reduced Arctic inversion has slowed down global warming by about 5% over the past 2 decades, and we anticipate that it will continue to do so with ongoing Arctic warming.

A review of ascorbic acid potentialities against oxidative stress induced in plants

A review of ascorbic acid potentialities against oxidative stress induced in plantsAscorbic acid (AA) currently holds a significant position in plant physiology, mainly due to its possession of antioxidant and cellular reductant etc.properties and its diverse roles in plant growth and development and the regulation of a broad spectrum of plant cellular mechanisms against environmental stresses. Some researchers suggest that endogenous AA has been implicated in the promotion of plant growth and development by involvement in a complex and enigmatic array of phytohormone-regulated signalling networks that ties together different environmental stresses. As it is evident from the present review, recent progress on AA potentiality in the tolerance of plants to environmental stresses has been impressive. Indeed, AA plays an important role in resistance to oxidative stresses such as heavy metal, saline, ultra-violet etc. Rapidly increasing evidence indicates that AA is centrally involved in several physiological processes but there has been much disagreement regarding the mechanism(s) by which AA reduces the damaging effects of such stresses in plants. Perhaps the role of AA in mediating tolerance to abiotic stress (e.g. UV, salinity and temperature, etc.) will lead to a greater research focus in the near future. In addition, AA might provide a suitably attractive target for the enhancement of crop production.

Effect of varying dietary levels of ω6 polyunsaturated fatty acids during the early ontogeny of the sea scallop, Placopecten magellanicus

This study investigated the effects of selected microalgal diets on growth, survival and fatty acid composition of sea scallops, Placopecten magellanicus, from egg hatching to postlarvae. Scallops were offered Pavlova lutheri (MONO) and Pavlova sp. (strain CCMP 459, P459) in combination with Chaetoceros muelleri (CHGRA) and P459 alone. These diets exhibited varying proportions of ω6 docosapentaenoic acid (22:5ω6, DPA) which represented 8.9% of total fatty acids in P459 compared to 5.4% in P459–CHGRA and only 0.5% in MONO–CHGRA. For experiment I, larvae were fed three diets (MONO–CHGRA, P459–CHGRA or P459 alone) for 35 days after fertilization. For experiment II, larvae were fed P459–CHGRA for 21 days and split among the three diets until 39 days post-fertilization. For experiment III, 4-day-old larvae were exposed to P459–CHGRA until they become postlarvae. MONO–CHGRA failed to produce pediveligers when fed to early veligers but yielded competent larvae when fed to late veligers. This may be related to the low ω6 DPA content of this diet. High accumulation of DPA by early veligers suggests a nutritional requirement for this fatty acid. Unialgal P459 supported lower pediveliger production and lower growth rate than other diets containing CHGRA. This may be the effect of higher levels of energetic substrates in CHGRA-containing diets. Finally, P459–CHGRA yielded the best survival and growth rate during the whole larval period. All three experiments showed marked arachidonic acid (20:4ω6, AA) accumulation in early veligers (4 to 21 days) and in pediveligers (32 to 43 days). Accumulation of AA during metamorphosis might reflect stimulation of immune functions due to pathogen infection and degradation of larval organs or the role of AA in cell signalling processes associated with tissue reorganization. Early veligers markedly accumulate DPA likely in response to low docosahexaenoic acid (22:6ω3, DHA) concentrations in the three tested diets. The potential role and effect of DPA as a substitute for DHA is discussed.

Conversation with George Vaillant

Conversation with George Vaillant

Accumulation of arachidonic acid-rich triacylglycerols in the microalga Parietochloris incisa (Trebuxiophyceae, Chlorophyta)

The freshwater green microalga Parietochloris incisa is the richest known plant source of the polyunsaturated fatty acid (PUFA), arachidonic acid (20:4ω6, AA). While many microalgae accumulate triacylglycerols (TAG) in the stationary phase or under certain stress conditions, these TAG are generally made of saturated and monounsaturated fatty acids. In contrast, most cellular AA of P. incisa resides in TAG. Using various inhibitors, we have attempted to find out if the induction of the biosynthesis of AA and the accumulation of TAG are codependent. Salicylhydroxamic acid (SHAM) affected a growth reduction that was accompanied with an increase in the content of TAG from 3.0 to 6.2% of dry weight. The proportion of 18:1 increased sharply in all lipids while that of 18:2 and its down stream products, 18:3ω6, 20:3ω6 and AA, decreased, indicating an inhibition of the Δ12 desaturation of 18:1. Treatment with the herbicide SAN 9785 significantly reduced the proportion of TAG. However, the proportion of AA in TAG, as well as in the polar lipids, increased. These findings indicate that while there is a preference for AA as a building block of TAG, the latter can be produced using other fatty acids, when the production of AA is inhibited. On the other hand, inhibiting TAG construction did not affect the production of AA. In order to elucidate the possible role of AA in TAG we have labeled exponential cultures of P. incisa kept at 25 °C with [1- 14C]arachidonic acid and cultivated the cultures for another 12 h at 25, 12 or 4 °C. At the lower temperatures, labeled AA was transferred from TAG to polar lipids, indicating that TAG of P. incisa may have a role as a depot of AA that can be incorporated into the membranes, enabling the organism to quickly respond to low temperature-induced stress.

Strange particle production in proton-nucleus reactions at ultrarelativistic energies

Enhanced yields of lambdas and other strange hadrons in experiments on nuclear targets at incident energies of 200 GeV have been recently reported by several experimental groups. We calculated events for proton projectiles on different targets in the framework of the relativistic quantum molecular dynamics approach which is based on string excitation and fragmentation with subsequent hadronic collisions. Here we address the question whether the experimentally found lambda enhancement in hadron-nucleus collisions can be understood by interactions of secondary hadrons formed in the target nucleus. Our results for Λ's, kaons and\(\bar \Lambda 's\) agree well with the experimental measurements. We find a doubling of lambda production in the target fragmentation region forp collisions on heavy targets due to nuclear cascading of the produced mesons. Resonances play an important role in creating strange quark pairs confirming earlier findings of their outstanding role inAA collisions.

Arachidonic acid as a mediator of some of the actions of phorbolmyristate acetate, a tumor promoter and inducer of differentiation

Phorbolmyristate acetate or 12-0-tetradecanyl phorbol 13-acetate (PMA or TPA) stimulates membrane phospholipases (phospholipase C or A2) resulting in the formation of diacylglyceride, free arachidonic acid, and increased amounts of arachidonic acid metabolites. Both PMA and AA are stimulators of the respiratory burst in phagocytic cells, induce inflammation, cause chromosomal aberrations, have antiviral activity and activate protein kinase C. The initial action of PMA is on the cell membrane and is concentrated largely in the lipid phase of cell membranes. This evidence suggests that the actions of PMA are in large part mediated by AA, released from the cell membrane lipid pool. Thus, it is likely that the ability of PMA to induce terminal differentiation in HL-60 cells and to suppress C-myc mRNA levels are also mediated by AA and/or its products. This may have relevance to the possible role of AA in the regulation of oncogenes and cancer.