Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

New evidence is provided regarding the direct effect of light on stomatal opening in the epidermis of the pea (Pisum sativum L. var Little Marvel) leaf. Light modulates the activity of a number of key enzymes involved in stomatal metabolism. When isolated epidermal strips are illuminated, phosphoenolpyruvate carboxylase, NADP-malate dehydrogenase, and NADP-isocitrate dehydrogenase are activated; and aspartate aminotransferase is inactivated. Sulfhydryl compounds, dithiothreitol and glutathione, enhance stomatal opening in epidermal strips both in light or darkness while the sulfhydryl reagent N-ethylmaleimide inhibits, indicating the possible involvement of sulfhydryl groups in stomatal movements. Further, light treatment increases measureable thiol levels in the epidermis about 3-fold. These results suggest that light modulation of enzymes in the epidermis may play a significant role in the mechanism of stomatal movement.
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PMID:Light and stomatal metabolism : I. Possible involvement of light modulation of enzymes in stomatal movement. 1666 47

Callus tissue cultures were developed from apical meristem regions of tumor-like ineffective root nodules of alfalfa. Callus growth was a function of tissue source and hormone composition and concentration. Callus derived from ineffective nodules also were shown not to contain Rhizobium meliloti.Glutamate dehydrogenase, glutamine synthetase, glutamate synthase, glutamate oxaloacetate transaminase and phosphoenolpyruvate carboxylase activities were present in callus cultures and in the respective nodule source used for callus induction. The mean specific activity of all enzymes evaluated was higher in callus cultures than in ineffective nodules. Quantitative but not qualitative differences in enzyme activities were evident between ineffective nodules and callus derived from these nodules. Tissue cultures derived from ineffective nodules may provide a model system to evaluate host plant-Rhizobium interactions.
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PMID:Tissue cultures derived from ineffective root nodules of alfalfa : callus initiation and enzymic comparisons. 1666 85

Effective (N(2)-fixing) alfalfa (Medicago sativa L.) and plant-controlled ineffective (non-N(2)-fixing) alfalfa recessive for the in(1) gene were compared to determine the effects of the in(1) gene on nodule development, acetylene reduction activity (ARA), and nodule enzymes associated with N assimilation and disease resistance. Effective nodule ARA reached a maximum before activities of glutamine synthetase (GS), glutamate synthase (GOGAT), aspartate aminotransferase (AAT), asparagine synthetase (AS), and phosphoenolpyruvate carboxylase (PEPC) peaked. Ineffective nodule ARA was only 5% of effective nodule ARA. Developmental profiles of GS, GOGAT, AAT, and PEPC activities were similar for effective and ineffective nodules, but activities in ineffective nodules were lower and declined earlier. Little AS activity was detected in developing ineffective nodules. Changes in GS, GOGAT, AAT, and PEPC activities in developing and senescent effective and ineffective nodules generally paralleled amounts of immunologically detectable enzyme polypeptides. Effective nodule GS, GOGAT, AAT, AS, and PEPC activities declined after defoliation. Activities of glutamate dehydrogenase, malate dehydrogenase, phenylalanine ammonia lyase, and caffeic acid-o-methyltransferase were unrelated to nodule effectiveness. Maximum expression of nodule N-assimilating enzymes appeared to require the continued presence of a product associated with effective bacteroids that was lacking in in(1) effective nodules.
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PMID:Nitrogen Assimilating Enzyme Activities and Enzyme Protein during Development and Senescence of Effective and Plant Gene-Controlled Ineffective Alfalfa Nodules. 1666 54

To assess the effects of subordinate social status on digestive function, metabolism, and enzyme activity in salmonid fish, juvenile rainbow trout Oncorhynchus mykiss were paired with size-matched conspecifics (<1.5% difference in fork length) for 5 d. Fish that were fasted for 5 d and fish sampled directly from the holding tank were used as control groups. Both subordinate and fasted fish experienced significant decreases in intestine mass (P = 0.043), and the gall bladder showed marked and significant changes in both size (P = 0.004) and appearance. These findings suggest that the negative effect of social subordination on digestive function reflects in large part a lack of feeding. Hepatic phosphoenolpyruvate carboxykinase activity was significantly higher in subordinate fish relative to dominants, whereas subordinate hepatic pyruvate kinase activity was significantly lower; activities of both enzymes were significantly correlated with plasma cortisol concentrations and behavior scores. Dominant-subordinate differences in the activities of these enzymes were eliminated by administration of the glucocorticoid receptor antagonist RU486, underlining a role for circulating cortisol in eliciting the differences. Significant increases relative to control fish were also detected in red and white muscles from subordinate fish in the activities of protein catabolic enzymes (aspartate aminotransferase, alanine aminotransferase, glutamate dehydrogenase). These differences occurred in the absence of any change in plasma free amino acid or ammonia concentrations, supporting an enhanced turnover of amino acids in muscle in subordinate fish. The results support the hypothesis that changes in metabolism, beyond those elicited by low food consumption, may be responsible at least in part for the low growth rates typical of subordinate fish and that these changes may be related specifically to circulating cortisol levels in subordinate fish.
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PMID:Growth depression in socially subordinate rainbow trout Oncorhynchus mykiss: more than a fasting effect. 1682 94

Sugarcane (Saccharum spp.) is a highly efficient biomass and sugar producing crop. Leaf reactions have been considered as potential rate-limiting step for sucrose accumulation in sugarcane stalks. To characterize the sugarcane leaf transcriptome, field-grown mature leaves from cultivar "SP80-3280" were analyzed using Serial Analysis of Gene Expression (SAGE). From 480 sequenced clones, 9,482 valid tags were extracted, with 5,227 unique sequences, from which 3,659 (70%) matched at least a sugarcane assembled sequence (SAS) with putative function; while 872 tags (16.7%) matched SAS with unknown function; 523 (10%) matched SAS without a putative annotation; and only 173 (3.3%) did not match any sugarcane ESTs. Based on gene ontology (GO), photosystem (PS) I reaction center was identified as the most frequent gene product location, followed by the remaining sites of PS I, PS II and thylakoid complexes. For metabolic processes, photosynthesis light harvesting complexes; carbon fixation; and chlorophyll biosynthesis were the most enriched GO-terms. Considering the alternative photosynthetic C(4) cycles, tag frequencies related to phosphoenolpyruvate carboxykinase (PEPCK) and aspartate aminotransferase compared to those for NADP(+)-malic enzyme (NADP-ME) and NADP-malate dehydrogenase, suggested that PEPCK-type decarboxylation appeared to predominate over NADP-ME in mature leaves, although both may occur, opposite to currently assumed in sugarcane. From the unique tag set, 894 tags (17.1%) were assigned as potentially derived from antisense transcripts, while 73 tags (1.4%) were assigned to more than one SAS, suggesting the occurrence of alternative processing. The occurrence of antisense was validated by quantitative reverse transcription amplification. Sugarcane leaf transcriptome provided new insights for functional studies associated with sucrose synthesis and accumulation.
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PMID:Serial analysis of gene expression in sugarcane (Saccharum spp.) leaves revealed alternative C4 metabolism and putative antisense transcripts. 1721 12

Stress responses to increased temperature in black porgy reared in freshwater (FBP) and seawater (SBP) were examined via endocrinological and blood physiological methods. A rise in temperature increased plasma cortisol levels, which were significantly higher in FBP compared to SBP. The stimulated expression of phosphoenolpyruvate carboxykinase (PEPCK) mRNA in liver might result from the high cortisol level, and this explains the observed higher plasma glucose levels in FBP versus SBP. Full-length cDNA sequence for PEPCK was determined by 3' and 5' RACE procedures. PEPCK cDNA clone was found to contain 2563 nucleotides including an open reading frame that encodes 624 amino acids. While aspartate aminotransferase (AST) and alanine aminotransferase (ALT) of FBP increased with temperature, there was no change in SBP. In FBP, T(3) were 2.3+/-0.3 ng/ml at 20 degrees C and significantly decreased to 1.0+/-0.3 ng/ml at 30 degrees C. On the other hand, in SBP, it were 3.1+/-0.5 ng/ml at 20 degrees C but significantly increased to 5.2+/-0.4 ng/ml at 30 degrees C. When comparing osmolality at the temperature of 30 degrees C and of 20 degrees C, the difference was found to be greater for FBP than SBP. Accordingly, the results suggest that FBP suffers greater stress than SBP with increased temperature, and provide stress responses and osmoregulatory abilities against stressors in black porgy that could differ depending on salinities.
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PMID:Molecular cloning of PEPCK and stress response of black porgy (Acanthopagrus schlegeli) to increased temperature in freshwater and seawater. 1741 46

While salicylates (non-steroidal anti-inflammatory drugs) have been detected in the aquatic environment, few studies have focused on the mechanism of action of these pharmaceuticals on aquatic organisms. We reported previously that salicylate disrupted the acute trophic hormone-stimulated corticosteroidogenesis in rainbow trout (Oncorhynchus mykiss) interrenal tissue in vitro. Here, we tested the hypothesis that this drug will inhibit the adaptive plasma cortisol response and the associated metabolic response to an acute stressor in trout. Fish were fed salicylate-laced feed (100 mg/kg body weight) for 3 days, subjected to an acute (5 min) handling disturbance and sampled 1, 4 and 24 h after the stressor exposure. Salicylate treatment attenuated the stressor-induced plasma cortisol but not glucose or lactate elevations. The disruption of cortisol response corresponded with a significant reduction in transcript levels of the steroidogenic acute regulatory protein (StAR), but not peripheral-type benzodiazepine receptor, cytochrome P450 side-chain cleavage or 11beta-hydroxylase. Salicylate did not modify the stressor-induced elevation of brain glucocorticoid receptor (GR) protein expression, while liver GR protein content was reduced. Salicylate impact on liver metabolic capacity involved depressed liver glycogen content, whereas no significant changes in liver hexokinase, glucokinase, lactate dehydrogenase, pyruvate kinase, phosphoenolpyruvate carboxykinase, aspartate aminotransferase and alanine aminotransferase activities were observed. Taken together, salicylate impairs the stressor-mediated plasma cortisol response and the associated liver metabolic capacity in trout. The mode of action of salicylate involves disruption of StAR and liver GR, two key proteins critical for cortisol production and target tissue responsiveness to this steroid, respectively.
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PMID:Salicylate impacts the physiological responses to an acute handling disturbance in rainbow trout. 1788 47

Nodulated lupins (Lupinus angustifolius cv. Wonga) were hydroponically grown under conditions of low phosphate (LP) or adequate phosphate (HP) to assess the effect of phosphoenolpyruvate carboxylase (PEPC)-derived organic acids on nitrogen assimilation in LP nodules. LP conditions are linked to altered organic acid metabolism, by the engagement of PEP metabolism via PEPC. In LP nodules, the enhanced organic acid synthesis may reduce the available organic carbon for nitrogen assimilation. The diversion of carbon between the organic acid- and amino acid pools was assessed through key nodular enzymes and (14)CO(2) metabolism. Under LP conditions, increased rates of organic acid synthesis via PEPC and malate dehydrogenase (MDH), coincided with reduced nitrogen assimilation via aspartate aminotransferase (AAT), aspartate synthetase (AS) and glutamine synthetase (GS)/glutamate synthase (GOGAT) activities. There was a preferential metabolism of nodular (14)CO(2) into organic acids and particularly into malate. High malate levels were associated with reduced N(2) fixation and synthesis of amino acids. These results indicate that phosphorus deficiency can enhance malate synthesis in nodules, but that excessive malate accumulation may inhibit N(2) fixation and nitrogen assimilation.
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PMID:Organic acid accumulation may inhibit N2 fixation in phosphorus-stressed lupin nodules. 1806 56

It is well established that grazing Neotyphodium coenophialum-infected forages results in reduced BW gain and serum prolactin concentrations of cattle. The objective of this study was to determine the potential effects of toxic endophyte-infected tall fescue consumption on blood metabolites, carcass characteristics, and content of proteins critical for AA metabolism in the liver, kidney, and LM tissue of growing steers. Steers grazed a low toxic endophyte (LE; 0.023 microg/g ergot alkaloids) tall fescue-mixed grass pasture (n = 9; BW = 266 +/- 10.9 kg; 5.7 ha) or a high toxic endophyte (HE; 0.746 microg/g of ergot alkaloids) tall fescue pasture (n = 10; BW = 267 +/- 14.5 kg; 5.7 ha) from June 14 through at least September 11 (> or =89 d). No difference was observed for BW (P < 0.10) for the overall 85-d growth period. Also, no differences were observed for ribeye area/100 kg of HCW (P > 0.91), backfat (P > 0.95), or backfat/100 kg of HCW (P > 0.67). However, ADG (P < 0.01), final BW (P < 0.05), HCW (P < 0.01), dressing percentage (P < 0.01), ribeye area (P < 0.01), whole liver wet weight (P < 0.01), and whole liver wet weight/100 kg of end BW (P < 0.01) were greater for LE steers than HE steers. After 85 d of grazing, serum concentrations of alkaline phosphatase (P < 0.05), alanine aminotransferase (P < 0.01), aspartate aminotransferase (P < 0.03), cholesterol (P < 0.01), lactate dehydrogenase (P < 0.01), and prolactin (P < 0.01) were less for HE than LE steers. At slaughter, hepatic content of cytosolic phosphoenolpyruvate carboxykinase (P < 0.01) was greater in HE steers than LE steers. Hepatic content of aspartate aminotransferase (P < 0.01) also was greater, whereas renal and LM content were not (P > or = 0.42). No differences (P > or = 0.15) were observed for hepatic, renal, and LM content of alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase, and 3 glutamate transport proteins. These data indicate that the HE steers displayed classic endophyte toxicity symptoms for growth and blood variables, classic symptoms that were concomitant with novelly identified altered glucogenic capacity of the liver and decreases in carcass characteristics.
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PMID:Growing steers grazing high versus low endophyte (Neotyphodium coenophialum)-infected tall fescue have reduced serum enzymes, increased hepatic glucogenic enzymes, and reduced liver and carcass mass. 1895 29

To determine the effect of metabolic acidosis on expression of L-Gln, L-Glu, and L-Asp metabolizing enzymes and transporters, the relative content of mRNA, protein, or mRNA and protein, of 6 enzymes and 5 transporters was determined by real-time reverse transcription-PCR and immunoblot analyses in homogenates of kidney, skeletal muscle, and liver of growing lambs fed a common diet supplemented with canola meal (control; n = 5) or HCl-treated canola meal (acidosis; n = 5). Acidotic sheep had a 790% greater (P = 0.050) expression of renal Na(+)-coupled neutral AA transporter 3 mRNA and a decreased expression of renal glutamine synthetase mRNA (47% reduction, P = 0.037) and protein (57% reduction, P = 0.015) than control sheep. No change in renal cytosolic phosphoenolpyruvate carboxykinase (protein and mRNA), glutaminase (mRNA), or L-Glu dehydrogenase (protein) was found. In skeletal muscle, acidotic sheep had 101% more (P = 0.026) aspartate transaminase protein than did control sheep, whereas no change in the content of 3 Na(+)-coupled neutral AA transporters (mRNA) or 2 high-affinity L-Glu transporter proteins was found. In liver, no change in the content of any assessed enzyme or transporter was found. Collectively, these findings suggest that tissue-level responses of sheep to metabolic acidosis are different than for nonruminants. More specifically, these results indicate the potential capacity for metabolism of L-Asp and L-Glu by skeletal muscle, and L-Gln absorption by kidneys, but no change in hepatic expression of L-Gln metabolism, elaborates previous metabolic studies by revealing molecular-level responses to metabolic acidosis in sheep. The reader is cautioned that the metabolic acidosis model employed in this study differs from the increased plasma lactate-induced metabolic acidosis commonly observed in ruminants fed a highly fermentable grain diet.
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PMID:Metabolic acidosis in sheep alters expression of renal and skeletal muscle amino acid enzymes and transporters. 1982 50


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