Essential Amino Acid Deficiency Research Articles

Primary hyperammonaemia: Current diagnostic and therapeutic strategies.

Primary hyperammonaemia is a term to describe an elevation of ammonia in blood or plasma due to a defect within the urea cycle, which is the pathway responsible for ammonia detoxification and arginine biosynthesis. Urea cycle disorders (UCDs) are rare diseases caused by genetic defects affecting any of the six enzymes or two transporters that are directly involved in the urea cycle function.The clinical situation is variable and largely depends on the time of onset. Newborns who are often affected by hyper-ammonaemic encephalopathy carry a potential risk of severe brain damage, which may lead to death. Outside the neonatal period, symptoms are very unspecific but most often neurological (with wide variability), psychiatric and/or gastrointestinal. Early identification of patients is extremely important to start effective treatment modalities immediately. The acute management includes detoxification of ammonia, which often requires extracorporeal means such as haemodialysis, and the use of intravenous drugs that work as nitrogen scavengers. Long-term management of patients with UCDs consists of a low-protein diet, which needs to be balanced and supplemented to avoid deficiencies of essential amino acids, trace elements or vitamins and the use of nitrogen scavengers.The reader will find here a brief overview describing the most relevant aspects of the clinical management of UCDs in an attempt to raise awareness for this important group of rare diseases.

STATES AND APPLICATION POTENTIAL OF FUNCTIONAL FOODS IN NUTRITION OF POPULATION AND MILITARY PERSONNEL

At present time, the compliance of energy costs and the chemical composition of foods in the daily diet with physiological needs of the body gains a particular relevance. Particular attention is paid to the use of functional food products - special products intended for systematic use by all age groups of a healthy population. Functional nutrition compensates for the deficiency of essential amino acids, polyunsaturated fatty acids (PUFA), vitamins, macro- and microelements, etc., as well as protects the body from the effects of pesticides and herbicides, antibiotics, dyes and preservatives, widely used in conventional products, and is used to strengthen health and prevent diseases caused by deficiencies in traditional nutrition. Such diseases include: obesity, non-insulin-dependent diabetes mellitus, hypertension, atherosclerosis, mental depression and others. In some professional groups, for example, in military athletes, the use of functional foods has been practiced for a long time. Currently, a fairly wide range of this group of products has been developed and is being produced. When developing a functional product, environmentally friendly raw materials of animal and vegetable origin, biologically active additives that improve functional and consumer qualities should be used. The high content of amino acids, proteins, carbohydrates, minerals, vitamins and other necessary biologically active substances, as well as good organoleptic characteristics and high consumer properties justify the feasibility of including functional products in the diet of military personnel, whose professional activity is characterized by high physical activity, requiring maximum use of functional resources organism. At the same time, military personnel are capable of completing official tasks at the limit of their physical capabilities, while maintaining relatively constant biochemical constants of the internal environment of the body. The information presented in the paper will be useful to the logistics and medical service specialists of the Russian Army and Navy and will serve as the basis for further development of the direction for the use of functional products for feeding military personnel.

The dynamic process of dietary soybean β-conglycinin in digestion, absorption, and metabolism among different intestinal segments in grass carp (Ctenopharyngodon idella).

The present study aimed to investigate the dynamic process of soybean β-conglycinin in digestion, absorption, and metabolism in the intestine of grass carp (Ctenopharyngodon idella). Fish fed with 80g β-conglycinin/kg diet for 7weeks, the intestinal digestive enzyme was extracted to hydrolyze β-conglycinin in vitro, the free amino acid and its metabolism product contents in intestinal segments were analyzed. The present study first found that β-conglycinin cannot be thoroughly digested by fish intestinedigestive enzyme and produces new products (about 60- and 55-kDa polypeptides). The indigestible β-conglycinin further caused the free amino acid imbalance, especially caused free essential amino acid deficiency in the proximal intestine but excess in the distal intestine. Moreover, these results might be partly associated with the effect of β-conglycinin in amino acid transporters and tight junction-regulated paracellular pathway. Finally, dietary β-conglycinin increased the content of amino acid catabolism by-product ammonia while decreased the amino acid anabolism product carnosine content in the proximal intestine and distal intestine. Thus, the current study first and systemically explored the dynamic process of β-conglycinin in digestion, absorption, and metabolism, which further supported our previous study that dietary β-conglycinin suppressed fish growth and caused intestine injure.

Study of the effect of different levels of arginine in feed on broiler chickens

Amino acids are the basic structural units of protein molecules in the body. Currently, about 300 amino acids are known, of which 26 are studied best. Amino acids or their derivatives (for example, immune bodies) are part of enzymes, hormones, pigments, and other specific substances that play a crucial role in digestive and metabolic processes. In the process of metabolism, many amino acids are synthesized in the body from other amino acids or compounds, and therefore they are called interchangeable. Amino acids that are not synthesized in the body or are formed in insufficient quantities are called indispensable. According to the content and ratio of essential amino acids, feed proteins are subdivided into full and inferior. Deficiency, absence, or imbalance of essential amino acids in animal diets is accompanied by a deterioration in protein use, metabolic disorders, and decreased productivity. The following amino acids are indispensable; arginine, viburnum, histidine, isoleucine, leucine, lysine, methionine, threonine, tryptophan, phenylalanine. Among the essential amino acids, especially important ones, are those called critical. These are lysine, methionine + cystia, threonine, and tryptophan. A deficiency, absence, or imbalance of essential amino acids in animal diets is accompanied by a deterioration in protein use, metabolic disorders, and decreased productivity. Research and production experiment was conducted within Olenka Poultry Factory LLC and the problematic research laboratory of feed additives of the Department of Animal Feeding and Feed Technology named after P. D. Pshenichny at the National University of Life and Environmental Sciences. The effective level of arginine in compound feed for broilers of the Cobb-500 cross was experimentally determined. The use of compound feed with arginine levels in the first rearing period (1 to 10 days) - 1.28%, in the second (11 to 22 days) - 1.15% and in the third (23 to 42 days) - 1.11% gives the opportunity to get broiler chickens at the age of 42 days, weighing 2.654 kg, at a feed expenditure of 1.78 kg per 1 kg of gain.

Molecular markers of dietary essential amino acid-deficiency

AbstractIntroduction:The quality of dietary protein sources became a particularly sensitive issue in the current debates on a rebalancing between animal and vegetable food sources.The ability of a protein to meet the nutritional requirements of essential amino acid (EAA) is the basis for assessing the quality of protein.The objective of this study was to characterize the impact of lysine- and threonine-deficient gluten-based diets on the metabolism of growing rats and to identify molecular markers of these diets.Materials and Methods:Growing rats were fed for 3 weeks with a threonine-supplemented and 70% lysine-deficient gluten diet; a lysine-supplemented and 47% threonine-deficient gluten diet; a gluten diet supplemented in lysine and threonine to meet all the AA requirements, and a control diet with milk protein to meet all the AA requirements.Body weight and food intake were measured daily. At the end of the experiment, tissues and biological fluids were removed. The body composition was analyzed, gene expression measurements involved in protein and lipid metabolism were performed and the urinary metabolome was analyzed by LC-MS. Statistical analysis was done by variance analysis and metabolome analysis by discriminant analysis of independent components.Results:This EAA deficiency does not modify the food intake. Lysine deficiency induces a decrease in body weight gain, and lean body mass, associated with an increased in proteolysis and a decreased in proteosynthesis, a decreased in bone mineral density, and no effect on lipid metabolism.Threonine deficiency induces a decrease in body weight gain, and liver and skin weight, without changes in protein metabolism, bone mineral density, and lipid metabolism. After approval of the deficiency model, the metabolomic analysis performed on urine samples revealed the presence of specific discriminating molecules of the diets and types of proteins.Discussion:EAA deficiency has an impact on the growth, and bone and protein metabolism of growing rats. These deficiency states have resulted in different metabolome profiles that could lead to the identification of specific molecular markers of protein sources and related to EAA deficiencies.

Вміст метгемоглобіну та карбоксигемоглобіну в еритроцитах щурів за умов токсичного ураження на тлі аліментарної депривації протеїну

The study of the content of total hemoglobin and its pathological derivates methemoglobin and carboxyhemoglobin in rats’ red blood cell under the toxic damage and alimentary protein deprivation are presented. In order to simulate the low-protein diet of animals for 28 days were kept, an isoenergy diet containing 4.7% protein, 10% fats and 85.3% carbohydrates, which was calculated according to the American Institute of Nutrition recommendations. The simulation of acute toxic damage was performed by per os acetaminophen-administration to experimental animals at doses of 1250 mg/kg of animal body weight. It was found that in experimental animals the 2-fold decrease in erythrocytes counts compared with the values of the control group was observed under the toxic damage after alimentary protein deprivation. In this case, both protein deficiency and the administration of acetaminophen toxic doses have a clear effect on the studied indicator. At the same time, a decrease of erythrocyte counts is accompanied by a simultaneous decrease of total hemoglobin content in rat erythrocyte hemolysate. In animals consuming a low protein diet, this may be due to a deficiency of essential amino acids involved in the synthesis of globin’s polypeptide chains. The maximal increase of methemoglobin content (5-fold compared with control) in rats’ erythrocyte hemolysate was recorded under the administration of acetaminophen toxic doses after alimentary protein deprivation. In these experimental conditions this may be associated with a decrease of methemoglobin reductase activity, which causes methemoglobin accumulates in erythrocytes in the form of Heinz bodies. An increase of the carboxyhemoglobin level in rats’ erythrocyte hemolysate of all the experimental groups compared with the control under the conditions of toxin administration after protein deficiency, probably indicates impaired synthesis and/or degradation of heme-containing proteins.

Temporal profiling of essential amino acids in developing maize kernel of normal, opaque-2 and QPM germplasm.

Maize, an important cereal crop, has apoor quality of endosperm protein due to the deficiency of essential amino acids, especially lysine and tryptophan. Discovery of mutants such as opaque-2 led to the development of nutritionally improved maize with a higher concentration of lysine and tryptophan. However, the pleiotropic effects associated with opaque-2 mutants necessitated the development of nutritionally improved hard kernel genotype, the present-day quality protein maize (QPM). The aim of present study was to analyze and compare the temporal profile of lysine and tryptophan in the developing maize kernel of normal, opaque-2 and QPM lines. A declining trend in protein along with tryptophan and lysine content was observed with increasing kernel maturity in the experimental genotypes. However, opaque-2 retained the maximum concentration of lysine (3.43) and tryptophan (1.09) at maturity as compared to QPM (lysine-3.05, tryptophan-0.99) and normal (lysine-1.99, tryptophan-0.45) lines. Opaque-2 mutation affects protein quality but has no effect on protein quantity. All maize types are nutritionally rich at early stages of kernel development indicating that early harvest for cattle feed would ensure a higher intake of lysine and tryptophan. Two promising lines (CML44 and HKI 1105) can be used for breeding high value corn for cattle feed or human food in order to fill the protein inadequacy gap. Variation in lysine and tryptophan content within QPM lines revealed that differential expression of endosperm modifiers with varying genetic background significantly affects nutritional quality, indicating that identification of alleles affecting amino acid composition can further facilitate QPM breeding program.

The Role of the Anabolic Properties of Plant- versus Animal-Based Protein Sources in Supporting Muscle Mass Maintenance: A Critical Review.

Plant-sourced proteins offer environmental and health benefits, and research increasingly includes them in study formulas. However, plant-based proteins have less of an anabolic effect than animal proteins due to their lower digestibility, lower essential amino acid content (especially leucine), and deficiency in other essential amino acids, such as sulfur amino acids or lysine. Thus, plant amino acids are directed toward oxidation rather than used for muscle protein synthesis. In this review, we evaluate the ability of plant- versus animal-based proteins to help maintain skeletal muscle mass in healthy and especially older people and examine different nutritional strategies for improving the anabolic properties of plant-based proteins. Among these strategies, increasing protein intake has led to a positive acute postprandial muscle protein synthesis response and even positive long-term improvement in lean mass. Increasing the quality of protein intake by improving amino acid composition could also compensate for the lower anabolic potential of plant-based proteins. We evaluated and discussed four nutritional strategies for improving the amino acid composition of plant-based proteins: fortifying plant-based proteins with specific essential amino acids, selective breeding, blending several plant protein sources, and blending plant with animal-based protein sources. These nutritional approaches need to be profoundly examined in older individuals in order to optimize protein intake for this population who require a high-quality food protein intake to mitigate age-related muscle loss.

Molecular Markers of Dietary Essential Amino Acid-deficiency (P08-059-19)

ObjectivesThe quality of dietary protein sources became a particularly sensitive issue in the current debates on a rebalancing between animal and vegetable food sources.The ability of a protein to meet the nutritional requirements of essential amino acid (EAA) is the basis for assessing the quality of protein.The objective of this study was to characterize the impact of lysine- and threonine-deficient gluten-based diets on the metabolism of growing rats and to identify molecular markers of these diets. MethodsGrowing rats were fed for 3 weeks with a threonine-supplemented and 70% lysine-deficient gluten diet; a lysine-supplemented and 47% threonine-deficient gluten diet; a gluten diet supplemented in lysine and threonine to meet all the AA requirements, and a control diet with milk protein to meet all the AA requirements.Body weight and food intake were measured daily. At the end of the experiment, tissues and biological fluids were removed. The body composition was analyzed, gene expression measurements involved in protein and lipid metabolism were performed and the urinary metabolome was analyzed by LC-MS. Statistical analysis was done by variance analysis and metabolome analysis by discriminant analysis of independent components. ResultsThese EAA deficiency does not modify the food intake. Lysine deficiency induces a decrease in body weight gain, and lean body mass, associated with an increased in proteolysis and a decreased in proteosynthesis, a decreased in bone mineral density, and no effect on lipid metabolism.Threonine deficiency induces a decrease in body weight gain, and liver and skin weight, without changes in protein metabolism, bone mineral density, and lipid metabolism. After approval of the deficiency model, the metabolomic analysis performed on urine samples revealed the presence of specific discriminating molecules of the diets and types of proteins. ConclusionsEAA deficiency has an impact on the growth, and bone and protein metabolism of growing rats. These deficiency states have resulted in different metabolome profiles that could lead to the identification of specific molecular markers of protein sources and related to EAA deficiencies. Funding SourcesThis study was funded by the UMR Nutrition Physiology and Ingestive Behavior. Supporting Tables, Images and/or Graphs▪

Integrated Remodeling of Gut-Liver Metabolism Induced by Moderate Protein Restriction Contributes to Improvement of Insulin Sensitivity.

ScopeProtein restriction (PR) is beneficial for relieving metabolic disorders and aging‐related diseases. However, extreme PR could result in malnutrition due to severe deficiency of essential amino acids. Therefore, the effect of moderate PR on insulin sensitivity is investigated.Methods and resultsThe growing and adult pigs are subjected to moderate PR by 15–30%. Plasma insulin concentration and insulin resistance index HOMA‐IR are significantly decreased upon moderate PR. Furthermore, IRS1/PI3K/AKT pathway in the basal state is enhanced in both liver and skeletal muscle. The adapted metabolism in the liver upon moderate PR is in support of improving insulin sensitivity. The liver shares a coordinated metabolic adaption in terms of energy metabolism and amino acid metabolism with the small intestine. Particularly, alteration of the metabolic footprint appeared in the portal venous blood, representing metabolites to be absorbed into liver after intestinal metabolism, is also in favor of improvement of insulin sensitivity.ConclusionIn summary, the study proves that moderate PR could improve insulin sensitivity from childhood to adulthood in a pig model, and sheds a new light on the role of integrated remodeling of gut and liver metabolism in the improved insulin sensitivity induced by moderate PR.

Gastrointestinal and hepatic enzyme activities in juvenile silvery-black porgy (Sparidentex hasta) fed essential amino acid-deficient diets.

As amino acids (AAs) are vital molecules in the metabolism of all living organisms and are the building blocks of enzymes, a 6-week feeding trial was conducted for determining the influence of dietary essential amino acid (EAA) deficiencies on pancreatic, plasma, and hepatic enzyme activities in silvery-black porgy (initial weight 4.7 ± 0.01g) juveniles. Eleven isoproteic (ca. 47%) and isoenergetic (ca. 20.5MJkg-1) diets were formulated including a control diet, in which 60% of dietary nitrogen were provided by intact protein (fish meal, gelatin, and wheat meal) and 40% by crystalline AA. The other 10 diets were formulated by 40% reduction in each EAA from the control diet. At the end of the experiment, fish fed with threonine-deficient diet showed the lowest survival rate (P < 0.05), whereas growth performance decreased in fish fed all EAA-deficient diets, although the reduction in body growth varied depending on the EAA considered. Pancreatic enzymes (trypsin, lipase, α-amylase, and carboxypeptidase A) activities significantly decreased in fish fed the EAA-deficient diets in comparison with fish fed the control diet (P < 0.05). Fish fed with the arginine-deficient diet had the highest plasma and liver alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase levels (P < 0.05). Plasma and liver lactate dehydrogenase and superoxide dismutase showed the highest and lowest values, respectively, in fish fed the arginine and lysine-deficient diets (P < 0.05). Plasma metabolites were significantly affected by dietary EAA deficiencies (P < 0.05). The results of this study suggesting dietary EAA deficiencies led to reduction in growth performance as well as pancreatic and liver malfunction. Furthermore, arginine and lysine are the most limited EAA for digestive enzyme activities and liver health in silvery-black porgy.

TRIB3 limits FGF21 induction during in vitro and in vivo nutrient deficiencies by inhibiting C/EBP–ATF response elements in the Fgf21 promoter

Mammals must be able to endure periods of limited food availability, and the liver plays a central role in the adaptation to nutritional stresses. TRIB3 (Tribbles homolog 3) is a cellular stress-inducible gene with a liver-centric expression pattern and it has been implicated in stress response regulation and metabolic control. In the current article, we study the involvement of TRIB3 in responses to nutrient deficiencies, including fasting for up to 48 h in mice. We show that hepatic expression of Trib3 is increased after 48 h of fasting and mice with a targeted deletion of the Trib3 gene present elevated hepatic triglyceride content and liver weight at 48 h, along with an upregulation of lipid utilization genes in the liver. Further, hepatic and serum levels of the metabolic stress hormone FGF21 are considerably increased in 48-h-fasted Trib3 knockout mice compared to wild type. Trib3 deficiency also leads to elevated FGF21 levels in the mouse liver during essential amino acid deficiency and in cultured mouse embryonic fibroblasts during glucose starvation. Reporter assays reveal that TRIB3 regulates FGF21 by inhibiting ATF4-mediated, C/EBP–ATF site-dependent activation of Fgf21 transcription. Based on chromatin immunoprecipitation from mouse liver, the binding of TRIB3 and ATF4, a transcription factor known to physically interact with TRIB3, is significantly increased at the Fgf21 promoter following 48 h of fasting. Thus, under nutrient-limiting conditions that stimulate ATF4 activity, TRIB3 is implicated in the regulation of metabolic adaptation by restraining the transcription of Fgf21.

Effects of dietary protein and essential amino acid deficiencies on growth, body composition, and digestive enzyme activities of silvery-black porgy (Sparidentex hasta)

A 6-week feeding trial was conducted to evaluate the effects of protein-free (PF) and essential amino-acid-deficient (EAAD) diets on the growth performance and digestive enzyme activities of silvery-black porgy (Sparidentex hasta) juveniles. Three experimental diets were formulated: a control diet in which 60% of dietary nitrogen was provided by intact protein (fish meal) and 40% by crystalline AA [(blends of essential amino acids (EAA) and none essential amino acids (NEAA)]; an essential amino-acid-deficient diet in which 60% of dietary N was provided by intact protein, whereas the rest was provided by NEAA and a protein-free (PF) diet, based on carbohydrate sources. Survival rates in fish fed the EAAD and PF diets were lower than in fish fed the control diet. Weight gain in fish fed with EAAD was 5.6 g lower than fish fed with the control diet. Furthermore, fish fed the PF diet lost weight and their final body weight was 12.2 g lower than the control group. Fish fed the PF diet had the highest whole-body moisture, but the lowest whole-body protein, lipid, threonine, aspartic acid, glutamic acid, and serine levels. Digestive pancreatic enzyme activities including trypsin, lipase, α-amylase, and carboxypeptidase A significantly decreased in fish fed EAAD and PF diets. The information obtained from this study testing two extreme diets (EAAD and PF) may serve for better understanding the impact of protein and EAA nutritional imbalances in fish performance.

Hemato-immunological and plasma biochemical responses of silvery-black porgy (Sparidentex hasta) fed protein and essential amino acid deficient diets

A 6-week feeding trial was conducted to evaluate the effects of protein free (PF) and essential amino acid deficient (EAAD) diets on the physiological responses of silvery-black porgy (Sparidentex hasta) juveniles. Three experimental diets were formulated: a control diet in which 60% of dietary nitrogen was provided by intact protein (fish meal) and 40% by crystalline AA [(blends of essential amino acids (EAAs) and non-essential amino acids (NEAAs)]; an essential amino acid deficient diet in which 60% of dietary N was provided by intact protein, whereas the rest was provided by NEAAs; and a protein free (PF) diet, which based on carbohydrate sources. Fish fed the PF and EAAD showed signs of anemia including lower red blood cells counts, hemoglobin, and hematocrit levels than control group. Plasma lysozyme activity and complements C3 and C4, as well as total immunoglobulin levels were drastically reduced in fish fed PF and EAAD diets. Plasma and liver alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase were significantly increased, but superoxide dismutase was decreased in fish fed PF and EAAD diets. Plasma total protein, albumin, high density lipoprotein, calcium, and inorganic phosphorous significantly decreased in fish fed PF and EAAD diets. The information obtained from this study testing to extreme diets (EAAD and PF diets) may serve for better understanding the impact of protein nutritional imbalances in fish.

Effects of dietary essential amino acid deficiencies on the growth performance and humoral immune response in silvery-black porgy (Sparidentex hasta) juveniles

A 6-week feeding trial was conducted for determining the effects of dietary essential amino acids (EAA) deficiencies on growth performance and non-specific immune responses in silvery-black porgy juveniles (4.7 ± 0.1 g initial weight). Eleven isoproteic (ca. 47%) diets were formulated including a control diet containing the optimum quantity of EAA, and ten EAA-deficient diets. All diets contained 36% fish meal and 18.5% crystalline EAA and non-essential amino acids (NEAA) as the main source of dietary proteins. All the EAA and NEAA incorporated in the crystalline amino acids mixture of the control diet simulated the amino acids profile of the fish meal. The other 10 EAA-deficient diets were formulated by the deletion of each of the 10 EAA (crystalline form) from the control diet and replaced by a mixture of NEAA for the adjustment of dietary nitrogen contents. At the end of the experiment, fish fed with threonine-deficient diet showed the lowest survival rate (p < .05), whereas growth performance decreased in fish fed all EAA-deficient diets, although the reduction in body growth varied depending on the EAA considered. Plasma total protein decreased in all experimental groups except for fish fed the phenylalanine-deficient diet. Fish fed with arginine- and lysine-deficient diets had the lowest plasma C3, C4, lysozyme, total immunoglobulin and total superoxide dismutase activity (p < .05). Present results indicated that lysine, methionine and threonine were the most limiting EAA in terms of growth performance; however, arginine, threonine and lysine were the most limiting EAA for innate immunity responses in silvery-black porgy juveniles.

Use of L- arginine in the treatment of comorbid pathology in neurological patients

Amino acids are the structural chemical units that make up proteins. The special importance of amino acids is that some of them - precursors of neurotransmitters which are necessary for normal functioning of the brain. The absence one of essential amino acid suspend the formation of protein. Correction of deficiency of essential amino acids and replacement carried out by different drugs. Recently, interest in preparations that contain arginine significantly increased. This interest caused by the importance of L- arginine in the body functioning, as L- Arginine is a precursor of nitric oxide (NO). Arginine (Valagyn) is a common post-translational modification of proteins tsytoplazmatycheskyh that has a unique transcriptional regulatory pathways. L-arginine showed a protective effect in ischemia / reperfusion injury, which can be widely used in various diseases of the cardio-sudinnoyi system and metabolic disorders

Calcium-Dependent Eukaryotic Initiation Factor 2α Phosphatase Restores Control to Anterior Piriform Cortex Neural Circuitry after Activation by Essential Amino Acid Deficiency

Essential (dietary-indispensable) amino acids (IAA)s are vital precursors for protein synthesis; they cannot be synthesized in metazoans but must be obtained from food to survive. In sensing a reduction of an IAA, the mammalian anterior piriform cortex (APC)Ɨ is rapidly activated. The initial behavioral response is an abrupt end to an IAA deficient meal about 20 min after meal onset. IAA depletion in the APC activates the conserved eukaryotic initiation factor 2α (eIF2α) kinase, GCN2, via uncharged tRNA. GCN2 kinase activity increases levels of phosphorylated eIF2α (P-eIF2α), which blocks global protein synthesis such that APC inhibitory elements with short half-lives cannot be replaced. This results in disinhibition of this highly sensitive brain area. Following APC activation, a reduction in P-eIF2α releases the blockade on protein synthesis to allow recovery of inhibition in the circuit and complete the homeostatic response, restoring control in the APC. A role for calcium (Ca2+) in regulating P-eIF2α was explored here using Ca2+ blockers with immunohistochemistry and electrophysiology in APC brain slices. The responses to IAA depletion in the APC were Ca2+ dependent, showing a role for Ca2+ in the system. Yet, the kinase activity of GCN2 was unaffected by intracellular Ca2+ chelation. Thus, control must be accomplished by phosphatase activity. We suggest that regulation of P-eIF2α, and neuronal stability in the APC, require the activity of a Ca2+-dependent subunit, protein phosphatase1, of the phosphatase acting on P-eIF2α. This would implicate the Ca2+/calmodlin dependent calcineurin, and the constitutive repressor of eIF2 phosphorylation (PPP1R15B/CReP) after GCN2 activation in the brain.

Regulating the expression of therapeutic transgenes by controlled intake of dietary essential amino acids

Widespread application of gene therapy will depend on the development of simple methods to regulate the expression of therapeutic genes. Here we harness an endogenous signaling pathway to regulate therapeutic gene expression through diet. The GCN2-eIF2α signaling pathway is specifically activated by deficiencies in any essential amino acid (EAA); EAA deficiency leads to rapid expression of genes regulated by ATF4-binding cis elements. We found that therapeutic genes under the control of optimized amino acid response elements (AAREs) had low basal expression and high induced expression. We applied our system to regulate the expression of TNFSF10 (TRAIL) in the context of glioma therapy and found that intermittent activation of this gene by EEA-deficient meals retained its therapeutic efficacy while abrogating its toxic effects on normal tissue. The GCN2-eIF2α pathway is expressed in many tissues, including the brain, and is highly specific to EAA deficiency. Our system may be particularly well suited for intermittent regulation of therapeutic transgenes over short or long time periods.

Honey bee foragers balance colony nutritional deficiencies

Honey bee colonies, foraging predominantly on a single pollen source, may encounter nutritional deficits. In the present study, we examined the nutritional resilience of honey bee colonies, testing whether foragers shift their foraging effort towards resources that complement a nutritional deficit. Eight honey bee colonies were kept in screened enclosures and fed for 1 week a pollen substitute diet deficient in a particular essential amino acid. Foragers were subsequently tested for a preference between the same diet previously fed, a different diet that was similarly deficient, or a diet that complemented the deficiency. Foragers preferred the complementary diet over the same or similar diets. Appetitive conditioning tests showed that bees were able to discriminate also between the same and similar diets. Overall, our results support the hypothesis that honey bees prefer dietary diversity, and that they do not just include novel sources but specifically target nutritionally complementary ones. Whereas we specifically focused on deficiencies in essential amino acids, we cannot rule out that bees were also complementing correlated imbalances in other nutrients, most notably essential fatty acids. The ability of honey bees to counter deficient nutrition contributes to the mechanisms which social insects use to sustain homeostasis at the colony level.

High Protein Intake Does Not Prevent Low Plasma Levels of Conditionally Essential Amino Acids in Very Preterm Infants Receiving Parenteral Nutrition.

We have shown that increasing protein intake using a standardized, concentrated, added macronutrients parenteral (SCAMP) nutrition regimen improves head growth in very preterm infants (VPIs) compared with a control parenteral nutrition (PN) regimen. VPIs are at risk of conditionally essential amino acid (CEAA) deficiencies because of current neonatal PN amino acid (AA) formulations. We hypothesized that the SCAMP regimen would prevent low plasma levels of CEAAs. To compare the plasma AA profiles at approximately day 9 of life in VPIs receiving SCAMP vs a control PN regimen. VPIs (<29 weeks' gestation) were randomized to receive SCAMP (30% more PN AA) or a control regimen. Data were collected to measure parenteral and enteral protein, energy, and individual AA intake and the first plasma AA profile. Plasma profiles of the 20 individual protogenic AA levels were measured using ion exchange chromatography. Plasma AA profiles were obtained at median (interquartile range [IQR]) age of 9 (8-10) days in both SCAMP (n = 59) and control (n = 67) groups after randomizing 150 VPIs. Median (IQR) plasma levels of individual essential AAs were higher than the reference population mean (RPM) in both groups, especially for threonine. SCAMP infants had higher plasma levels of essential AAs than did the controls. Median (IQR) plasma levels of glutamine, arginine, and cysteine (CEAAs) were lower than the RPM in both groups. Plasma AA levels in PN-dependent VPIs indicate there is an imbalance in essential and CEAA provision in neonatal PN AA formulations that is not improved by increasing protein intake.