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Amino Acid Content (amino + acid_content)
Kinds of Amino Acid Content Selected AbstractsReproductive diapause and the bacterial symbiosis in the sycamore aphid Drepanosiphum platanoidisECOLOGICAL ENTOMOLOGY, Issue 3 2000A. E. Douglas Summary 1. Parthenogenetic adults of the sycamore aphid Drepanosiphum platanoidis exhibited reproductive diapause for 4,6 weeks in the summer. 2. The diapausing aphids had small gonads (accounting for just 13% of the total aphid protein content) bearing small (< 0.5 mm long) and developmentally immature embryos. There was no evidence of embryo resorption. 3. The diapausing aphids had significantly depressed essential amino acid content and elevated glutamine content, relative to reproductively active D. platanoidis. 4. The reproductive characteristics and amino acid titres of the diapausing aphids resemble those of aphids lacking functional symbiotic bacteria. Uncoupling of maternal and embryo growth and suppression of bacterial function are proposed as key elements in the diapause of D. platanoidis. [source] Biological and biochemical differences between in vitro- and in vivo-reared Exorista larvarumENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2006Maria Luisa Dindo Abstract Quantitative and qualitative parameters of Exorista larvarum (L.) (Diptera: Tachinidae) reared on two insect-material-free artificial media and in the factitious host Galleria mellonella L. (Lepidoptera: Pyralidae) were compared. Significantly higher puparial yields and weights were obtained in both a milk-based and a veal homogenate-based medium than in the factitious host. Longevity and parasitization rates were not different between the in vitro- and in vivo-reared flies. Despite the greater puparial weight of the veal medium-reared E. larvarum females, the number of eggs laid by these females on host larvae was not higher than that of females reared under the other two rearing conditions. Moreover, in a complementary experiment, with homogeneous puparial weights of milk medium- and host-reared females, the former oviposited fewer eggs. Hence, puparial weight alone is not a reliable quality parameter for E. larvarum reared on artificial media. Lower amino acid content, with a deficiency in aromatic amino acids and an excess in proline, was found for in vitro third instar parasitoid larvae reared on both media compared to the in vivo-reared ones. These results suggest a correlation between the amino acid deficiency and imbalance of medium-reared larvae and the lower number of eggs laid by the females obtained. [source] Characterizing the pigment composition of a variable warning signal of Parasemia plantaginis larvaeFUNCTIONAL ECOLOGY, Issue 4 2010Carita Lindstedt Summary 1.,Aposematic animals advertise their defences to predators via warning signals that often are bright colours combined with black patterns. Predation is assumed to select for large pattern elements and conspicuousness of warning signals because this enhances avoidance learning of predators. However, conspicuousness of the colour pattern can vary among individuals of aposematic species, suggesting that warning signal expression may be constrained by opposing selection pressures. If effective warning signals are costly to produce, variation in signal expression may be maintained via physiological trade-offs. To understand the costs of signalling that might underlay both physiological and ecological trade-offs, it is crucial to identify the pigments involved in aposematic traits, how they or their precursors are acquired and how their production and/or deposition interact with other physiological processes. 2.,We characterized the pigments responsible for the genetically and phenotypically variable orange-black warning signal of the hairy larvae of an Arctiid moth, Parasemia plantaginis. We tested orange and black coloured hairs for the presence of six candidate pigment types using high-performance liquid chromatography, spectral and solubility analyses. 3.,After excluding the presence of carotenoids, ommochromes, pterins and pheomelanins in orange hairs, our results suggest that tiger moth larvae produce their orange warning signal by depositing both diet-derived flavonoids and trace levels of synthesized eumelanin in their hairs. The nearby black hairs are coloured by eumelanin. 4.,In light of previous studies, we conclude that although a large orange patch increases the 1larvae's antipredator efficacy, variation in the size of orange patches within a population can be driven by scarcity of flavonoids in diet. However, traces of eumelanin found in the orange hairs of the larvae may also play a significant role in the maintenance of the signal pattern on poor quality diets. 5.,The goal of the future studies will be to test the condition dependence of pigment deposition in aposematic colour patterns by directly manipulating relevant nutritional parameters such as dietary flavonoid or nitrogen content (i.e. amino acid content). [source] Dietary amino acids fed in free form or as protein do differently affect amino acid absorption in a rat everted sac modelJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2008J. A. Nolles Summary In the present study, the effect of free amino acid (FAA) diets on the intestinal absorption rate of methionine and leucine was studied ,ex vivo' with rats adapted for different periods of time to the diets, using the everted sac method. The adaptation period to the 21% FAA diet with an amino acid content based on casein was either, 0 (no adaptation, N-ADA), 5 (short-term adaptation, ST-ADA), or 26,33 days (long-term adaptation, LT-ADA). Within the ST-ADA and the LT-ADA groups, three different levels of methionine were included: 50%, 100% and 200% of the level normally present in casein. All diets were iso-nitrogenous and iso-caloric. After the adaptation period (0, 5, or 26,33 days), intestinal everted sacs were prepared. Methionine or leucine was added to the medium as transport substrate. The methionine absorption rate of the rats of the LT-ADA groups was higher than that of the N-ADA groups. Furthermore, adaptation to 200% dietary methionine levels caused a significantly slower leucine absorption compared to the 100%, and 50% group. Methionine absorption was similar in the 100% and 200% groups, but the absorption of methionine in the 50% group was enhanced in the distal part of the intestines. We concluded that in response diets with 21% FAAs as only amino acid source, amino acid absorption is decreased to avoid toxic effects of high levels of methionine in the circulation. [source] Quality and Functional Characteristics of Chungkukjang Prepared with Various Bacillus sp.JOURNAL OF FOOD SCIENCE, Issue 4 2005Isolated from Traditional Chungkukjang ABSTRACT: Bacillus circulans, Brevibacillus brevis, B. licheniformis, B. coagulans, B. subtilis, and B. sterothermophillus were isolated and identified from chungkukjangs (Korean traditional soybean paste fermented for a few day). Chungkukjang was prepared on a laboratory scale with soybeans and the isolated strains. Characteristics of the chungkukjangs including slime material content, free amino acid content, sensory qualities, and antimutagenicity were determined. The content of slime material, which is an important indicator of the quality of chungkukjang, was highest in B. licheniformis -inoculated chungkukjang, andlowestin B. sterothermophillus -inoculated chungkukjang. The total content of glycine, glutamic acid, aspartic acid, and arginine, which contribute a savory taste to chungkukjangs, was highest in B. licheniformis-inoculated chungkukjang. The content of leucine, which gives a bitter taste, was highest inB. brevis -inoculated chungkukjang. Sensory evaluation revealed that chungkukjangs made using B. licheniformis and B. subtilishad a weak bitter taste and strong sweet and savory taste and good color, so their overall acceptability was high. Chungkukjang fermented with B. circulans and B. licheniformis inhibited N-Methyl-N,-nitro-N-nitrosoguanidine (MNNG) mutagenicity by more than 80%. B. licheniformis-inoculated chungkukjang exhibited the highest antimutagenicity against and aflatoxin B1 (AFB1) and MNNG. These results suggest that using B. licheniformis to ferment chungkukjang increases the antimutagenic properties and improves the sweet and savory taste by increasing glycine, glutamic acid, aspartic acid, and arginine concentrations. [source] Antibiotic activity of pentadecapeptides modelled from amino acid descriptorsJOURNAL OF PEPTIDE SCIENCE, Issue 2 2001Tore Lejon Abstract Pentadecapeptides based on modified murine lactoferricin (LFM) sequences show varying degrees of antibacterial activity against Escherichia coli and Staphylococcus aureus. By means of projections to latent structures (PLS), a good correlation is obtained if the biological activity is modelled as a function of variables describing peptide properties, e.g. ,-helicity, hydrophobicity/hydrophilicity and charge. Using variables derived from a principal component analysis (PCA) of all naturally occurring amino acids, it is possible to describe the amino acid content of the peptides using three variables per amino acid position. The resulting descriptor matrix is then used to develop quantitative structure,activity relationships (QSAR). It is shown that the theoretically derived descriptors model the activity of the peptides better than the earlier model, and that properties of the peptides other than antibacterial activity can be predicted. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd. [source] NITZSCHIA OVALIS (BACILLARIOPHYCEAE) MONO LAKE STRAIN ACCUMULATES 1,4/2,5 CYCLOHEXANETETROL IN RESPONSE TO INCREASED SALINITY,JOURNAL OF PHYCOLOGY, Issue 2 2009Fernando Garza-Sánchez The growth of microalgae in hypersaline conditions requires that cells accumulate osmoprotectants. In many instances, these are polyols. We isolated the diatom Nitzschia ovalis H. J. Arn. from the saline and alkaline water body Mono Lake (CA, USA). This isolate can grow in salinities ranging from 5 to 120 parts per thousand (ppt) of salt but normally at 90 ppt salinity. In this report, we identified the major polyol osmoprotectant as 1,4/2,5 cyclohexanetetrol by electron ionization-mass spectrometry (EI,MS), 1H, 13C nuclear magnetic resonance spectroscopy (NMR), and infrared (IR) and showed an increase in cellular concentration in response to rising salinity. This increase in the cyclitol concentration was evaluated by gas chromatography of the derived tetraacetylated cyclohexanetetrol obtaining an average of 0.7 fmol · cell,1 at 5 ppt and rising to 22.5 fmol · cell,1 at 120 ppt. The 1,4/2,5 cyclohexanetetrol was also detected in the red alga Porphyridium purpureum. Analysis of the free amino acid content in N. ovalis cultures exposed to changes in salinity showed that proline and lysine also accumulate with increased salinity, but the cellular concentration of these amino acids is about 10-fold lower than the concentration of 1,4/2,5 cyclohexanetetrol. The comparison of amino acid concentration per cell with cyclitol suggests that this polyol is important in compensating the cellular osmotic pressure due to increased salinity, but other physiological functions could also be considered. [source] Differential Increase in Taurine Levels by Low-Dose Ethanol in the Dorsal and Ventral Striatum Revealed by Microdialysis With On-Line Capillary ElectrophoresisALCOHOLISM, Issue 7 2004A Smith Ethanol increases taurine efflux in the nucleus accumbens or ventral striatum (VS), a dopaminergic terminal region involved in positive reinforcement. However, this has been found only at ethanol doses above 1 g/kg intraperitoneally, which is higher than what most rats will self-administer. We used a sensitive on-line assay of microdialysate content to test whether lower doses of ethanol selectively increase taurine efflux in VS as opposed to other dopaminergic regions not involved in reinforcement (e.g., dorsal striatum; DS). Adult male rats with microdialysis probes in VS or DS were injected with ethanol (0, 0.5, 1, and 2 g/kg intraperitoneally), and the amino acid content of the dialysate was measured every 11 sec using capillary electrophoresis and laser-induced fluorescence detection. In VS, 0.5 g/kg ethanol significantly increased taurine levels by 20% for 10 min. A similar increase was seen after 1 g/kg ethanol, which lasted for about 20 min after injection. A two-phased taurine efflux was observed with the 2.0 g/kg dose, where taurine was increased by 2-fold after 5 min but it remained elevated by 30% for at least 60 min. In contrast, DS exhibited much smaller dose-related increases in taurine. Glycine, glutamate, serine, and ,-aminobutyric acid were not systematically affected by lower doses of ethanol; however, 2 g/kg slowly decreased these amino acids in both brain regions during the hour after injection. These data implicate a possible role of taurine in the mechanism of action of ethanol in the VS. The high sensitivity and time resolution afforded by capillary electrophoresis and laser-induced fluorescence detection will be useful for detecting subtle changes of neuronally active amino acids levels due to low doses of ethanol. [source] Antioxidant activity of peptide fractions derived from cottonseed protein hydrolysateJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2010Dandan Gao Abstract BACKGROUND: Cottonseed protein is widely regarded as a potential source of nutrients for humans and animals, but it is mainly used as forage in China. In the present study, Neutrase was employed to hydrolyse cottonseed protein to produce a hydrolysate with antioxidant activity suitable for conversion to high-value products. The antioxidant potential of the cottonseed protein hydrolysate (CPH) and its fractions was investigated using different in vitro methods. Furthermore, the amino acid composition of the CPH fractions was determined to evaluate the relationship between antioxidant activity and amino acid composition. RESULTS: The CPH prepared using Neutrase was separated into four fractions (I, II, III and IV) by gel filtration on Sephadex G-25. All fractions were effective antioxidants, with fraction III (0.8,1.2 kDa) showing the strongest activity. The amino acid analysis showed that fraction III also had the highest total amino acid content (616.8 g kg,1 protein) and was rich in Phe, His, Pro, Met, Ile and Cys compared with the other fractions. CONCLUSION: The results showed that the hydrolysate derived from cottonseed protein, particularly fraction III, could be a natural antioxidant source suitable for use as a food additive. Copyright © 2010 Society of Chemical Industry [source] Preparation and antioxidant activity of wheat gluten hydrolysates (WGHs) using ultrafiltration membranesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2008Xiangzhen Kong Abstract BACKGROUD: Many hydrolysates from animal and plant proteins have been found to possess physiological activities. Wheat gluten, an important by-product of the wheat starch industry, is produced worldwide in enormous quantities. In this study, wheat gluten hydrolysates (WGHs) were obtained by enzymatic hydrolysis and fractionated using ultrafiltration membranes. The antioxidant activities of the hydrolysates were investigated by various antioxidant assays, including the ability to inhibit the autoxidation of linoleic acid and the scavenging effect on free radicals. Amino acid composition and molecular weight distribution were also evaluated to determine their relationship with antioxidant activity. RESULTS: The pepsin hydrolysate (PeWGH) had the highest activity and was ultrafiltrated into three major types, PeWGH I (5,10 kDa), PeWGH II (3,5 kDa) and PeWGH III (<3 kDa). PeWGH III showed stronger inhibition of the autoxidation of linoleic acid and higher scavenging activity against 2,2-diphenyl-1-picrylhydrazyl, superoxide and hydroxyl free radicals. Furthermore, PeWGH III had the highest total hydrophobic amino acid content (45.11 g per 100 g protein), and its molecular weight distribution ranged from 1700 to 100 Da. CONCLUSION: The low molecular weight and amino acid composition of PeWGHs were found to be strongly correlated with their antioxidant activity. PeWGH could be used as a natural antioxidant in the pharmaceutical and food industries in the future. Copyright © 2008 Society of Chemical Industry [source] Nutritive value of chicken and potato mixtures for infant and preschool children feedingJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2003Angela Sotelo Abstract Two chicken/potato protein mixtures (50:50 and 60:40) were prepared for use in formulas of high nutritive value and low cost for the diet of undernourished children and those with lactose intolerance. The proximate analysis and amino acid content of the raw materials and mixtures were determined and the chemical score (CS) was calculated. The proximate analysis and amino acid content of a commercial soybean formula were used as reference. The protein quality of the mixtures was evaluated by protein efficiency ratio (PER) and digestibility measurements. The protein content of cooked chicken and potato on a dry basis was 889 and 70 g kg,1 respectively and the carbohydrate content of potato was 762 g kg,1. Tryptophan was the limiting amino acid in chicken for infants according to the 1985 FAO pattern (CS = 76), but not for preschool children. Valine was limiting in potato for both infants and preschool children (CS = 56 and 88 respectively). Tryptophan was limiting in both 50:50 and 60:40 mixtures for infants; also the PER was higher in the 60:40 mixture and not significantly different from the control (casein), but both were different from the 50:50 mixture. Since both chicken and potato are available even for low-income people, a formula prepared in the 60:40 ratio is of potential benefit for infants or preschool children who have lactose intolerance, mainly in developing countries. Copyright © 2003 Society of Chemical Industry [source] Compositional and degradative changes during the manufacture of dry-cured ,lacón'JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2003José M Lorenzo Abstract The gross and mineral composition, the main physicochemical parameters, the protein extractability and the proteolytic (nitrogen fractions and free amino acids) and lipolytic (acidity index and free fatty acids) changes were studied throughout the manufacturing process of five batches of dry-cured ,lacón', a traditional Spanish meat product made from the fore-ham of the pig following a similar technological process to that of dry-cured ham. The main compositional characteristics of this product are the high NaCl content and the low moisture content at the end of the curing process. The pH remained fairly stable (around 6) throughout the whole process and a fall in aw was observed, reaching very low (0.767 ± 0.052) final average values. It was noted that 76% of the sarcoplasmic and 83% of the myofibrillar proteins became insoluble during the manufacturing process. The values of the different nitrogen fractions increased in a significant manner during manufacture, reaching low final values that indicate that ,lacón' undergoes a low level of proteolysis in comparison with other products manufactured by similar technologies. The high NaCl content and the intense dehydration suffered during the manufacturing process appear to be the principal causes of this reduced protein degradation. In accordance with the limited increase in the ,-amino acidic nitrogen during ripening, the total free amino acid content increased slightly but significantly from average values of 4371 mg kg,1 dry matter in fresh pieces to average values of 13 020 mg kg,1 dry matter in pieces at the end of the ripening process. The profile of free amino acids in the final product was similar to that observed by other authors in dry-cured ham. The acidity of the fat increased by a factor of five. The final average values (49.9 g oleic acid kg,1) were lower than those determined in dry-cured ham, which indicates that ,lacón' undergoes less lipolysis during the ripening process than dry-cured ham. C18 : 1, C18 : 2 and C16 were the most intensively released fatty acids during curing. The profile of free fatty acids in the end product was in agreement with that observed by other authors in dry-cured ham. Copyright © 2003 Society of Chemical Industry [source] Effect of industrial processing on amino acid content of broccoliJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2001M Antonia Murcia Abstract The levels of amino acids in broccoli stems and florets before and after various blanching times (in the case of freezing) and after bottling have been studied to elucidate to what extent nutrient quality is affected by industrial processing. The following amino acids (mg,kg,1 fresh weight) were identified by ion exchange chromatography in raw broccoli florets: glutamine (1338), proline (732), asparagine (578), valine (310), arginine (296), isoleucine (204), threonine (169), leucine (166), phenylalanine (159), aspartic acid (140), lysine (127), alanine (122), tyrosine (105), S -methylcysteine (96), histidine (89), ornithine (59), glutamic acid (44), ,-aminobutyric acid (31), glycine (11) and serine (0.2). Raw stems contained the same amino acids but at lower levels (p,<,0.05). The levels of all these amino acids fell during both industrial processes studied (bottling and freezing after blanching for 60, 90, 120 and 150,s), particularly in the frozen samples (losses of 50,70% in the florets and 20,50% in the stems). In summary, losses of broccoli amino acids were lower if blanching times were kept short. The optimal blanching time at 94,°C for florets and stems intended for freezing was 90,s, and this did not result in any great loss of nutritional value related to amino acid content. Bottled florets had greater nutritional value than those frozen after being exposed to the longest blanching times (120 and 150,s). © 2001 Society of Chemical Industry [source] Replacement of Fish Meal with Soybean Meal in the Production Diets of Juvenile Red Snapper, Lutjanus campechanusJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2005D. Allen Davis The replacement of fish meal with soybean meal in fish diets has met with varying degrees of success. Quite often, poor responses to high soybean meal diets are either due to shifts in the nutrient profile or a reduced palatability of the diet when fish meal is removed. The present research was designed to evaluate the replacement of menhaden fish meal with solvent-extracted soybean meal in practical diets containing 10% poultry by-product meal and formulated to contain 40% protein, 8% lipid, and a total sulfur amino acid content of > 3.0% of the protein. The response of red snapper (mean initial weight 10.9 g) to diets containing graded levels of fish meal (30,20, 10, 0%) as well as the response to a low fish meal diet (10%) without poultry by-product meal were evaluated over a 6-wk growth period. Significant (P± 0.05) differences in final mean weight, percent weight gain, and feed conversion were observed. Final weights (percent gain) ranged from 30.9 g (185.5%) for fish offered diets with 30% fish meal to 12.6 g (16.3%) for fish offered diets with 0% fish meal. Corresponding feed conversion efficiencies ranged from 60.1% to 7.7%. No significant differences were observed for survival between treatment means. Although there was a clear reduction in performance as the fish meal was replaced with soybean meal, the use of 10% poultry by-product meal or 10% fish meal resulted in similar performance of the fish. This is a good indication that poultry by-product meal does not have palatability problems and could be used as a substitute. The present findings suggest that replacing fish meal with high levels of soybean meal appears to reduce the palatability of the diet. While the cost reducing benefit, with respect to the replacement of fish meal, has been shown with other species, before high levels of inclusion can be efficiently utilized further research is needed to address the palatability problems observed with red snapper. [source] Effects of etomidate on free intracellular amino acid concentrations in polymorphonuclear leucocytes in vitroACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2000J. Mühling Background: Previous studies have shown the inhibitory effects of etomidate on polymorphonuclear leucocyte (PMN) function. No reports exist, however, regarding free intracellular amino acid metabolism, although physiological cell metabolism and basic cell functions rely upon a balanced intracellular amino acid content and the cell membrane-mediated separation of cellular amino acids from the extracellular plasma amino acid pool. Thus, in the current study, we evaluated the effects of etomidate on free intracellular amino acid metabolism in PMN. Methods: With ethics committee approval, blood was withdrawn from 35 healthy volunteers and incubated (1 h) either with 0 ,g/ml, 0.0156 ,g/ml, 0.0625 ,g/ml or 0.5 ,g/ml of etomidate as well as with its additives (propylene glycol and Lipofundin MCT® 10%). The PMN were separated using standardized Percoll® -gradient and centrifugation procedure before deep-freezing and lyophilization techniques were employed. All PMN samples were dissolved in methanol/H2O, and the concentrations of free intracellular amino acids were monitored using both novel advanced PMN-separation and high-performance liquid chromatography techniques. Results: Etomidate influenced important free amino acid profiles in PMN in a dose-dependent manner, indicating complex changes of cellular amino acid turnover. Neither propylene glycol nor Lipofundin MCT® 10% changed free amino acid concentrations in PMN. Conclusions: For the first time, the effects of etomidate on free intracellular amino acid metabolism in PMN have been investigated. Our results draw attention to the biochemical pathways which may be involved in etomidate-induced alterations in PMN function and cellular immunocompetence. [source] Comparison of Structural and Chemical Properties of Black and Red Human Hair Melanosomes,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2005Yan Liu ABSTRACT Melanosomes in black and red human hair are isolated and characterized by various chemical and physical techniques. Different yields of 4-amino-hydroxyphenolanaline by HI hydrolysis (a marker for pheomelanin) and pyrrole-2,3,5-tricarboxylic acid by KMnO4/H+ oxidation (a marker for eumelanin) indicate that the melanosomes in black hair are eumelanosomes, whereas those in red hair are mainly pheomelanosomes. Atomic force microscopy reveals that eumelanosomes and pheomelanosomes have ellipsoidal and spherical shapes, respectively. Eumelanosomes maintain structural integrity upon extraction from the keratin matrix, whereas pheomelanosomes tend to fall apart. The black-hair eumelanosomes have an average of 14.6 ± 0.5% amino acids content, which is attributed to the internal proteins entrapped in the melanosomes granules. The red-hair melanosomes contain more than 44% of amino acid content even after extensive proteolytic digestion. This high content of amino acids and the poorly reserved integrity of red-hair melanosomes suggest that some proteins are possibly covalently bonded with the melanin constituents in addition to those that are entrapped inside the melanin species. Soluene solubilization assay indicates the absorbance of melanin per gram of sample, adjusted for the amino acid content, is a factor of 2.9 greater for the black-hair melanosomes than the red-hair melanosomes. Metal analysis reveals significant amounts of diverse heavy metal ions bound to the two types of melanosomes. The amount of Cu(II) and Zn(II) are similar but Fe(III) content is four times higher in the red-hair melanosomes. 13C solid-state nuclear magnetic resonance spectra and infrared spectra are presented and are shown to be powerful techniques for discerning differences in the amino acid contents, the 5,6-dihydroxyindole-2-carboxylic acid:5,6-dihydroxyindole ratio, and the degree of cross-linking in the pigment. Excellent agreement is observed between these spectral results and the chemical degradation data. [source] Amino acid budgets in three aphid species using the same host plantPHYSIOLOGICAL ENTOMOLOGY, Issue 3 2001J. P. Sandström Abstract. Nutrient provisioning in aphids depends both on the composition of ingested phloem sap and on the biosynthetic capabilities of the aphid and its intracellular symbionts. Amino acid budgets for three aphid species, Rhopalosiphum padi (L.), Schizaphis graminum (Rondani) and Diuraphis noxia (Mordvilko), were compared on a single host plant species, wheat Triticum aestivum L. Ingestion of amino acids from phloem, elimination of amino acids in honeydew, and the content of amino acids in aphids tissue were measured. From these values, ingestion rates were estimated and compared to honeydew and to estimated composition of aphid proteins. Ingestion rate was lowest in D. noxia due to low growth rate and low honeydew production; intermediate in S. graminum due to higher growth rate and intermediate honeydew production; and highest in R. padi, which had the highest rates for both variables. Both D. noxia and S. graminum induced increases in the amino acid content of ingested phloem. These changes in phloem content, combined with differences in ingestion rates, resulted in large differences among aphids in estimated rates of ingestion of individual amino acids. In honeydew, most essential amino acids were found in low amounts compared with the amounts ingested, especially for methionine and lysine. A few amino acids (arginine, cystine, histidine and tryptophan) were more abundant in honeydew of some aphids, suggesting oversupply. Aphid species differed in the composition of free amino acids in tissue but showed very similar composition in protein, implying similar requirements among the aphids. In R. padi and D. noxia, most essential amino acids were ingested in amounts insufficient for growth, implying dependence on symbiont provisioning. In S. graminum, most amino acids were ingested in amounts apparently sufficient for growth. [source] SlCCD7 controls strigolactone biosynthesis, shoot branching and mycorrhiza-induced apocarotenoid formation in tomatoTHE PLANT JOURNAL, Issue 2 2010Jonathan T. Vogel Summary The regulation of shoot branching is an essential determinant of plant architecture, integrating multiple external and internal signals. One of the signaling pathways regulating branching involves the MAX (more axillary branches) genes. Two of the genes within this pathway, MAX3/CCD7 and MAX4/CCD8, encode carotenoid cleavage enzymes involved in generating a branch-inhibiting hormone, recently identified as strigolactone. Here, we report the cloning of SlCCD7 from tomato. As in other species, SlCCD7 encodes an enzyme capable of cleaving cyclic and acyclic carotenoids. However, the SlCCD7 protein has 30 additional amino acids of unknown function at its C terminus. Tomato plants expressing a SlCCD7 antisense construct display greatly increased branching. To reveal the underlying changes of this strong physiological phenotype, a metabolomic screen was conducted. With the exception of a reduction of stem amino acid content in the transgenic lines, no major changes were observed. In contrast, targeted analysis of the same plants revealed significantly decreased levels of strigolactone. There were no significant changes in root carotenoids, indicating that relatively little substrate is required to produce the bioactive strigolactones. The germination rate of Orobanche ramosa seeds was reduced by up to 90% on application of extract from the SlCCD7 antisense lines, compared with the wild type. Additionally, upon mycorrhizal colonization, C13 cyclohexenone and C14 mycorradicin apocarotenoid levels were greatly reduced in the roots of the antisense lines, implicating SlCCD7 in their biosynthesis. This work demonstrates the diverse roles of MAX3/CCD7 in strigolactone production, shoot branching, source,sink interactions and production of arbuscular mycorrhiza-induced apocarotenoids. [source] The redistribution of protein sulfur in transgenic rice expressing a gene for a foreign, sulfur-rich proteinTHE PLANT JOURNAL, Issue 1 2003N. D. Hagan Summary Sulfur amino acid composition is an important determinant of seed protein quality. A chimeric gene encoding sunflower seed albumin (SSA), one of the most sulfur-rich seed storage proteins identified so far, was introduced into rice (Oryza sativa) in order to modify cysteine and methionine content of the seed. Analysis of a transgenic line expressing SSA at approximately 7% of total seed protein revealed that the mature grain showed little change in the total sulfur amino acid content compared to the parental genotype. This result indicated that the transgenic rice grain was unable to respond to the added demand for cysteine and methionine imposed by the production of SSA. Analysis of the protein composition of the transgenic grain showed changes in the relative levels of the major seed storage proteins, as well as some non-storage proteins, compared to non-transgenic controls. Changes observed at the protein level were concomitant with differences in mRNA accumulation but not always with the level of transcription. The limited sulfur reserves appeared to be re-allocated from endogenous proteins to the new sulfur sink in the transgenic grain. We hypothesize that this response is mediated by a signal transduction pathway that normally modulates seed storage protein composition in response to environmental fluctuations in sulfur availability, via both transcriptional and post-transcriptional control of gene expression. [source] Reduced amino acid content in transgenic potato tubers due to antisense inhibition of the leaf H+/amino acid symporter StAAP1THE PLANT JOURNAL, Issue 2 2003Wolfgang Koch Summary Transport processes across the plasma membrane of leaf vascular tissue are essential for transport and distribution of assimilates. In potato, leaves are the predominant sites for nitrate reduction and amino acid biosynthesis. From there, assimilated amino acids are exported through the phloem to supply tubers with organic nitrogen. To study the role of amino acid transporters in long-distance transport and allocation of organic nitrogen in potato plants, a gene encoding a functional, leaf-expressed amino acid permease StAAP1 was isolated. Similar to the sucrose transporter SUT1, StAAP1 expression was induced during the sink-to-source transition, indicating a role in phloem loading. To test the role of StAAP1, expression was inhibited by an antisense approach. Transgenic plants with reduced StAAP1 expression were phenotypically indistinguishable from wild type, as were photosynthetic capacity and tuber yield. However, tubers from antisense StAAP1 plants showed up to 50% reduction in free amino acid contents. In comparison, starch content was not affected or tended to increase relative to wild type. The reduction in all amino acids except aspartate in the antisense plants is consistent with the properties of amino acid permeases (AAPs) found in heterologous systems. The results demonstrate an important role for StAAP1 in long-distance transport of amino acids and highlight the importance of plasma membrane transport for nutrient distribution in plants. [source] Physiological responses of juvenile wedge sole Dicologoglossa cuneata (Moreau) to high stocking densityAQUACULTURE RESEARCH, Issue 7 2009Marcelino Herrera Abstract Physiological responses to a high stocking density were tested in juvenile wedge sole Dicologoglossa cuneata (Moreau). Fish were kept at low (1 kg m,2), medium (3 kg m,2) and high (9 kg m,2) stocking densities for 22 days. No differences in the weight, length, survival and hepatosomatic index were observed among treatments. Basal plasma cortisol and osmolality were found to be directly and positively related to stocking density. A mild increase in plasma glucose was seen at medium density, and plasma protein was elevated at medium and high densities. The liver glucose and glycogen content was inversely related to stocking density. The liver triglyceride level was significantly elevated at the highest density, and the ,-amino acid content decreased at the highest density. In muscle, glucose levels were significantly higher in fish kept at the lowest density; the ,-amino acid content was elevated in fish kept at high density. In conclusion, plasma cortisol levels indicated an increasing stress level depending on the culture density, but significant changes in energy reserves did not occur in tissue (mainly liver and muscle glycogen and glucose reserves were significantly affected). [source] Prediction of Activity, Synthesis and Biological Testing of anti-HSV Active PeptidesCHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2006Håvard Jenssen Herpes simplex virus infections can be treated with a number of drugs, but as for all pathogens, there is a constant need for new therapies. In the search for lead compounds some peptides have proven to possess an antiviral effect, but it is still unclear what mechanisms are responsible for this effect. We wish to report on the use of principal properties of amino acids for developing quantitative structure,activity relationships (QSAR:s) as a tool for modelling peptide activity and predicting the activity of new peptides. In order to test the reliability of the method, new peptides have been designed by using multivariate methodology, synthesized and tested for a number of responses. Two of the new peptides synthesized were active at lower concentrations than experienced before regarding entry and herpes simplex virus activity, but they were not able to completely inhibit viral infection. This may reflect differences in mode of action of peptides depending on the amino acid content. [source] Single-point mutations at the surface of MB-1Trp lead to important changes in its conformational propertiesCHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2004M. Sasseville Abstract:, Protein design is currently used for the creation of new proteins with desirable traits. In our lab we focus on the synthesis of proteins with high essential amino acid content having potential applications in animal nutrition. One of the limitations we face in this endeavour is achieving stable proteins despite a highly biased amino acid content. We report here the synthesis and the characterization of three variants of MB-1Trp in which two solvent-exposed Leu have been replaced by Glu allowing for the formation of new salt bridges at the surface of the protein. Although both mutations were expected to be similar (i.e. same mutation in a comparable local environment), they appear to have different effects on MB-1Trp as shown by far-UV circular dichroism, thermal denaturation, fluorescence and proteolytic resistance measurements. For the mutation Leu68Glu, an increase in the protein melting temperature of 6 °C was observed. Surprisingly, the mutation in position Leu19Glu led to a decrease in melting temperature and a modification of tertiary structure. [source] Effects of drying process on biochemical and microbiological quality of silverside (fish) Atherina lagunaeINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2010Salah Selmi Summary Changes in biochemical and microbiological quality of silverside during two drying process were investigated. Total fatty acid and amino acid contents in silverside were 5.42 and 10.9 g 100 g,1 fresh sample, respectively, in which, palmitic acid and glutamic acid were the most abundant. N-3 and n-6 polyunsaturated fatty acids (PUFA) levels were 0.59 and 0.62 g 100 g,1 fresh silverside respectively. After hot air and solar drying treatments, Peroxide value and thiobarbituric acid reactive substances of the total lipids increased significantly (P < 0.05) to reach 2.58 and 3.41 meq active O2 kg,1 oil and 0.87 and 1.27 mg MA kg,1 oil, respectively. Fatty acid profile of non-polar lipid remains unchanged during experimental drying process. However, PUFA (% of total fatty acids) of polar lipid decreased significantly (P < 0.05) during both drying process with lower levels in solar drying process. Drying conditions had a significant effect on the microbiological quality. Therefore, mesophiles and total coliforms increased within drying treatment with higher counts in solar drying process. [source] Proteolysis During the Fermentation of Ethanol-Supplemented MisoJOURNAL OF FOOD SCIENCE, Issue 8 2001R.Y.-Y. ABSTRACT: Steam-cooked soybeans mixed with rice koji (2:1, w/w) were ground into a fine paste, combined with NaCl (0 to 12.5%) or sucrose (0 to 25%), and supplemented with 15% ethanol for fermentation. The proteolytic activities decreased with NaCl or sucrose; the dose-response effect of NaCl was much more effective than that of sucrose. When fermented with 15% ethanol and 12.5% sucrose at various moisture contents from 30.6 to 53.0%, proteolysis increased proportionally to the increase of moisture content. Mechanical agitation enhanced proteolysis. After 4 w of fermentation, free amino acid contents were higher in products fermented without pH control than in products fermented with pH control. [source] Protein digestibility-corrected amino acid scores, acceptability and storage stability of ready-to-eat supplementary foods for pre-school age children in TanzaniaJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2005Theobald CE Mosha Abstract This study was conducted to evaluate protein quality, acceptability and storage stability of processed cereal,bean,sardine composite foods for pre-school age children in Tanzania. Four composite products namely corn,bean,sardine meal (CBSM), bean meal (BM), sorghum,bean,sardine meal (SBSM) and rice,bean,sardine meal (RBSM) were formulated to maximize the amino acid score for pre-school age children and were processed by extrusion, drum-processing and conventional cooking. The products were evaluated for true protein digestibility (TPD) and protein digestibility-corrected amino acid score (PDCAAS). The TPD and PDCAAS were highest in the extruded products. The TPD values for the products ranged from 82 to 93%. The PDCAAS values for the composite foods were 64,86% and were greater than the minimum value of 60% recommended by FAO/WHO/UNU. There were no significant (p > 0.05) variations in the amino acid contents for foods processed by extrusion, drum-processing or conventional cooking. Threonine was most limiting in the CBSM, SBSM and RBSM while methionine + cysteine were most limiting in the BM. Sensory evaluation showed that, relative to the traditional cornmeal,Uji, the extruded CBSM and SBSM had significantly superior (p , 0.05) texture and highly acceptable color and taste. Storage of the products up to 16 weeks at 38 °C resulted in a small but significant increase (p , 0.05) in the malondialdehyde concentrations; nevertheless, the levels remained within the acceptable range found in processed commercial supplements. Total acids, pH and organoleptic attributes did not change significantly (p > 0.05) during storage and the foods were acceptable to the end of the storage period. Copyright © 2005 Society of Chemical Industry [source] Comparison of Structural and Chemical Properties of Black and Red Human Hair Melanosomes,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2005Yan Liu ABSTRACT Melanosomes in black and red human hair are isolated and characterized by various chemical and physical techniques. Different yields of 4-amino-hydroxyphenolanaline by HI hydrolysis (a marker for pheomelanin) and pyrrole-2,3,5-tricarboxylic acid by KMnO4/H+ oxidation (a marker for eumelanin) indicate that the melanosomes in black hair are eumelanosomes, whereas those in red hair are mainly pheomelanosomes. Atomic force microscopy reveals that eumelanosomes and pheomelanosomes have ellipsoidal and spherical shapes, respectively. Eumelanosomes maintain structural integrity upon extraction from the keratin matrix, whereas pheomelanosomes tend to fall apart. The black-hair eumelanosomes have an average of 14.6 ± 0.5% amino acids content, which is attributed to the internal proteins entrapped in the melanosomes granules. The red-hair melanosomes contain more than 44% of amino acid content even after extensive proteolytic digestion. This high content of amino acids and the poorly reserved integrity of red-hair melanosomes suggest that some proteins are possibly covalently bonded with the melanin constituents in addition to those that are entrapped inside the melanin species. Soluene solubilization assay indicates the absorbance of melanin per gram of sample, adjusted for the amino acid content, is a factor of 2.9 greater for the black-hair melanosomes than the red-hair melanosomes. Metal analysis reveals significant amounts of diverse heavy metal ions bound to the two types of melanosomes. The amount of Cu(II) and Zn(II) are similar but Fe(III) content is four times higher in the red-hair melanosomes. 13C solid-state nuclear magnetic resonance spectra and infrared spectra are presented and are shown to be powerful techniques for discerning differences in the amino acid contents, the 5,6-dihydroxyindole-2-carboxylic acid:5,6-dihydroxyindole ratio, and the degree of cross-linking in the pigment. Excellent agreement is observed between these spectral results and the chemical degradation data. [source] How does photorespiration modulate leaf amino acid contents?PLANT CELL & ENVIRONMENT, Issue 7 2002A dual approach through modelling, metabolite analysis Abstract The aim of this work was to establish the quantitative impact of photorespiration on leaf amino acid contents. Attached leaves of wheat and potato were incubated for 30,40 min under defined conditions in which net CO2 uptake (A) was manipulated by irradiance, ambient CO2 or ambient O2. The incubated portion of the leaf was sampled by a rapid-quench method and photorespiratory flux (vo) was modelled from the measured rate of net CO2 uptake. In both wheat and potato, the ratio between glycine and serine showed a strong positive correlation with vo. Aspartate and alanine correlated negatively with vo but glutamate and glutamine showed less clear relationships. In potato, glutamate and glutamine did not correlate clearly with either A or vo. In wheat, glutamine showed a general increase with A but no relationship with vo, whereas 2-oxoglutarate contents correlated positively with vo and negatively with A. As a result, glutamine : glutamate and glutamine : 2-oxoglutarate increased with net CO2 uptake in wheat, observations that are attributed primarily to imperfect and variable coupling between the supply of NH3 in primary nitrogen assimilation and the associated delivery of 2-oxoglutarate to the chloroplast. A simple theoretical analysis is used to illustrate the potentially marked impact of primary nitrogen assimilation on leaf glutamine, even against a background of high rates of photorespiratory ammonia recycling. [source] Reduced amino acid content in transgenic potato tubers due to antisense inhibition of the leaf H+/amino acid symporter StAAP1THE PLANT JOURNAL, Issue 2 2003Wolfgang Koch Summary Transport processes across the plasma membrane of leaf vascular tissue are essential for transport and distribution of assimilates. In potato, leaves are the predominant sites for nitrate reduction and amino acid biosynthesis. From there, assimilated amino acids are exported through the phloem to supply tubers with organic nitrogen. To study the role of amino acid transporters in long-distance transport and allocation of organic nitrogen in potato plants, a gene encoding a functional, leaf-expressed amino acid permease StAAP1 was isolated. Similar to the sucrose transporter SUT1, StAAP1 expression was induced during the sink-to-source transition, indicating a role in phloem loading. To test the role of StAAP1, expression was inhibited by an antisense approach. Transgenic plants with reduced StAAP1 expression were phenotypically indistinguishable from wild type, as were photosynthetic capacity and tuber yield. However, tubers from antisense StAAP1 plants showed up to 50% reduction in free amino acid contents. In comparison, starch content was not affected or tended to increase relative to wild type. The reduction in all amino acids except aspartate in the antisense plants is consistent with the properties of amino acid permeases (AAPs) found in heterologous systems. The results demonstrate an important role for StAAP1 in long-distance transport of amino acids and highlight the importance of plasma membrane transport for nutrient distribution in plants. [source] Biotransformation of tuna waste by co-fermentation into an aquafeed ingredientAQUACULTURE RESEARCH, Issue 9 2009Hena Vijayan Abstract Dried skipjack tuna (Katsuwonus pelamis) waste (red meat, gills, viscera, fins, etc.) were mixed with 25% wheat flour and inoculated with a starter culture of Lactobacillus plantarum National Collection of Industrial Microorganisms (NCIM) 2912 (108,109 cells mL,1) and Bacillus licheniformis MTCC 6824 (107,108 cells mL,1). Changes in the nutritional quality (crude protein, crude fat, crude ash, crude fibre and nitrogen-free extract and aminoacids) were monitored during a fermentation period of 14 days. The proximate analysis showed significant changes in the composition of L. plantarum -fermented tuna (LPFT) and B. licheniformis -fermented tuna (BLFT) from the unfermented raw materials. Fermentation of tuna waste has resulted in a significant (P<0.05) increase in the protein content of tuna waste between days 6 and 12. All the amino acid contents in BLFT increased during fermentation, whereas, in LPFT the levels of serine, histidine, tyrosine, methionine, cystine and phenylalanine contents were decreased. A marginal increase in calcium and phosphorus levels was recorded in the fermented products. The results of the study suggest that LPFT or BLFT can be used as a novel aquafeed ingredient for different fish species. [source] | |||||||||||||||||||||||||||||||