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Abstract In this study was evaluated the influence of glutamine supplementation on the endogenous content of amino acids, proteins, total phenolics, flavonoids and proanthocyanidins in Bacupari callus. The explants were inoculated in MS medium, MS with half concentration of the nitrogen salts (MS½) and nitrogen-free MS, supplemented with glutamine (5, 10, 30 and 60mM) named as Gln5, Gln10, Gln30 and Gln60. Amino acids and proteins were analyzed after 20, 80 and 140 days and the secondary metabolites on the 140th day. There was no difference in the amino acids on the 20th day. On the 80th day the treatments MS and MS½ presented the lowest levels. On the 140th day MS and MS½ presented the lowest amino acid concentration and Gln10 the highest. Concerning proteins, there was difference only on the 140th day, being the highest concentrations observed in Gln5, and the lowest in MS½ treatment. Total phenolics content was higher in the treatment Gln60 and lowest in MS. Treatments Gln5, Gln10, Gln30 and MS½ were statistically equal. For flavonoids, the highest values occurred in the treatments Gln30, Gln60 and MS½ and the lowest in Gln5, Gln10 and MS. Similarly, for the proanthocyanidins the highest concentrations were observed in treatment Gln60 and the lowest in Gln5 and MS. In conclusion, the treatment with 60mM of glutamine favors the protein accumulation and production of secondary metabolites in Bacupari callus. Resumo Nesse estudo foi avaliado o efeito da suplementação com glutamina no conteúdo endógeno de aminoácidos, proteínas, fenólicos totais, flavonoides e proantocianidinas em calos de Bacupari. Os explantes foram inoculados em meio MS, meio MS com metade da concentração de dos sais de nitrogênio (MS½) e meio MS sem nitrogênio suplementado com glutamina (5, 10, 30 e 60mM) denominados como Gln5, Gln10, Gln30 e Gln60. Os aminoácidos e as proteínas foram analisados após 20, 80 e 140 dias e os metabólitos secundários no 140° dia. Não houve diferença nos aminoácidos no 20° dia. No 80° dia os tratamentos MS e MS½ apresentaram os menores níveis. No 140° dia, MS e MS½ apresentaram as menores concentrações de aminoácidos e o Gln10 as maiores. A respeito das proteínas, houve diferença apenas no 140° dia, sendo as maiores concentrações observadas nos tratamentos Gln, e as menores no MS½. O conteúdo de fenólicos totais foi maior no tratamento Gln60 e menor no MS. Os tratamentos Gln5, Gln10, Gln30 e MS½ foram estatisticamente iguais. Para os flavonóides, os maiores valores ocorreram nos tratamentos Gln30, Gln60 e MS½ e os menores no Gln5, Gln10 e MS. Da mesma forma, para as proantocianidinas, as maiores concentrações foram observadas no tratamento Gln60 os menores no Gln5 e MS. Em conclusão, o tratamento com 60 mM de glutamina favorece o acúmulo de proteínas e a produção de metabólitos secundários em calos de Bacupari.

Theanine, a unique amino acid found in tea plants, has many important physiological functions. Theanine can be enzymatically synthesized via the γ-glutamyltranspeptidation reaction. In this study, we described a new method of theanine synthesis using the L-glutamine-Zn(Ⅱ) (Zn(Gln)₂) complex instead of glutamine as the donor, which successfully reduced the side autotranspeptidation reaction and led to higher yield of theanine. We prepared the Zn(Gln)₂ complexes and showed that they are stable in liquid bulk under 9.0 pH. After using the Zn(Gln)₂ in the γ-glutamyltranspeptidation reaction, we utilized HPLC and Mass spectrometry analysis to demonstrated that Zn(Gln)₂ was an more effective γ-glutamyl donor than glutamine. The autotranspeptidation reaction was restrained effectively. As a result, the theanine yield and the conversion rate for glutamine were vastly improved. In a reaction mixture containing 48 mM of Zn(Gln)₂, 1.6 M ethylamine, and 0.5 U/mL GGT, the final concentration of theanine obtained was 61.3 mM after incubation at 37℃ for three hours. The conversion rate for glutamine was 63.8%, which showed a 16.9% increase as compared to when using glutamine alone as the donor substrate.

PII is a protein allosteric effector in Escherichia coli and other bacteria that indirectly regulates glutamine synthetase at the transcriptional and post-translational levels in response to nitrogen availability. Data supporting the notion that plants have a nitrogen regulatory system(s) includes previous studies showing that the levels of mRNA for plant nitrogen assimilatory genes such as glutamine synthetase (GLN) and asparagine synthetase (ASN) are modulated by carbon and organic nitrogen metabolites. Here, we have characterized a PII homolog (GLB1) in two higher plants, Arabidopsis thaliana and Ricinus communis (Castor bean). Each plant PII-like protein has high overall identity to E. coli PII (50%). Western blot analyses reveal that the plant PII-like protein is a nuclear-encoded chloroplast protein. The PII-like protein of plants appears to be regulated at the transcriptional level in that levels of GLB1 mRNA are affected by light and metabolites. To initiate studies of the in vivo function of the Arabidopsis PII-like protein, we have constructed transgenic lines in which PII expression is uncoupled from its native regulation. Analyses of these transgenic plants support the notion that the plant PII-like protein may serve as part of a complex signal transduction network involved in perceiving the status of carbon and organic nitrogen. Thus, the PII protein found in archaea, bacteria, and now in higher eukaryotes (plants) is one of the most widespread regulatory proteins known, providing evidence for an ancestral metabolic regulatory mechanism that may have existed before the divergence of these three domains of life

The influence of increased nitrate concentration-14 (control) and 140 mmol L-¹ (T)-in hydroponic culture on ammonia assimilation in cucumber (Cucumis sativus L. cv. Xintaimici) seedlings was investigated. The results showed that NH₃ accumulation in the roots and leaves of T seedlings increased significantly, indicating that NH3 toxicity might be involved in nitrate stress. Under control conditions, GS and GOGAT activity were much higher in the leaves than in the roots, whereas GDH activity was much higher in the roots than in the leaves. Correlation analysis showed that NH₃ concentration had a strong negative linear relationship with GDH activity in the roots but had a strong negative linear relationship with GS and GOGAT activity in the leaves. These results indicate that NH₃ might be assimilated primarily via GDH reaction in the roots and via GS/GOGAT cycle in the leaves. Short-term nitrate stress resulted in the increase of GS and GOGAT activity in the roots and GDH activity in the leaves of T seedlings, indicating possible shifts in ammonia assimilation from the normal GDH pathway to GS/GOGAT pathway in the roots and from the normal GS/GOGAT pathway to the GDH pathway in the leaves under nitrate stress, but with the increase of treatment time, GS, GOGAT, and GDH activity in the roots and leaves of T seedlings decreased possibly due to low water potential and NH₃ toxicity.

A variety of agricultural plant species, including corn, respond to insect herbivore damage by releasing large quantities of volatile compounds and, as a result, become highly attractive to parasitic wasps that attack the herbivores. An elicitor of plant volatiles, N-(17-hydroxylinolenoyl)-L- glutamine, named volicitin and isolated from beet armyworm caterpillars, is a key component in plant recognition of damage from insect herbivory. Chemical analysis of the oral secretion from beet armyworms that have fed on 13C-labeled corn seedlings established that the fatty acid portion of volicitin is plant derived whereas the 17-hydroxylation reaction and the conjugation with glutamine are carried out by the caterpillar by using glutamine of insect origin. Ironically, these insect-catalyzed chemical modifications to linolenic acid are critical for the biological activity that triggers the release of plant volatiles, which in turn attract natural enemies of the caterpillar

O estudo foi conduzido para verificar a influência da glutamina no turnover do carbono em tecidos de leitões. Nove porcas foram cobertas e receberam dietas compostas predominantemente por grãos de plantas do ciclo fotossintético C4 durante gestação e lactação. Aos 21 dias de idade, 48 leitões foram distribuídos aleatoriamente nos tratamentos: T1 = dieta C3, sem suplementação de glutamina, e T2 = dieta C3, suplementada com 1% de glutamina. Nos dias 0, 1, 2, 3, 4, 5, 8, 11, 15, 20, 29 e 46 pós-desmame, foram abatidos dois leitões/tratamento. Amostras dos músculos Psoas major e Masseter, fígado e pâncreas foram coletadas e analisadas quanto à composição e δ‰13C e mensurada a substituição do carbono em função do tempo. A glutamina acelerou a substituição do carbono em ambos os músculos, como observado pelos valores de meia-vida (T) destes tecidos (T = 51,4 e 21,7 dias para Masseter e 31,5 e 20,3 dias para Psoas major, nos tratamentos sem e com suplementação de glutamina, respectivamente). Os valores de meia-vida do carbono das vísceras indicam que esse aminoácido também acelerou o turnover do carbono nestes órgãos. Os resultados indicam estímulo anabólico da glutamina sobre os tecidos avaliados.

The activities of glutamate dehydrogenase (GDH), glutamate synthetase (GS) and three forms glutamate synthase (GOGAT) were studied in the leaves, stems and roots of Pisum arvense. The obtained data indicate that at lower tissue NH4+ concentration a decisive role in nitrogen assimilation in the leaves and stems is played by the GS/GOGAT pathway, while in the roots by GDH and in less degree by GS/GOGAT. High amounts acumulated NH4+ ions set off a detoxication mechanism which includes NADH-GDH, common to all tissues. Only 7 day-old leaves did the detoxication of NH4+ which takes place with the involvement of NADH-GOGAT and NADPH-GOGAT

Three-week-old maize (Zea mays L.) plants were submitted to light/dark cycles and to prolonged darkness to investigate the occurrence of sugar-limitation effects in different parts of the whole plant. Soluble sugars fluctuated with light/dark cycles and dropped sharply during extended darkness. Significant decreases in protein level were observed after prolonged darkness in mature roots, root tips, and young leaves. Glutamine and asparagine (Asn) changed in opposite ways, with Asn increasing in the dark. After prolonged darkness the increase in Asn accounted for most of the nitrogen released by protein breakdown. Using polyclonal antibodies against a vacuolar root protease previously described (F. James, R. Brouquisse, C. Suire, A. Pradet, P. Raymond [1996] Biochem J 320: 283-292) or the 20S proteasome, we showed that the increase in proteolytic activities was related to an enrichment of roots in the vacuolar protease, with no change in the amount of 20S proteasome in either roots or leaves. Our results show that no significant net proteolysis is induced in any part of the plant during normal light/dark cycles, although changes in metabolism and growth appear soon after the beginning of the dark period, and starvation-related proteolysis probably appears in prolonged darkness earlier in sink than in mature tissues

O estudo foi conduzido para verificar a influência da glutamina no turnover do carbono em tecidos de leitões. Nove porcas foram cobertas e receberam dietas compostas predominantemente por grãos de plantas do ciclo fotossintético C4 durante gestação e lactação. Aos 21 dias de idade, 48 leitões foram distribuídos aleatoriamente nos tratamentos: T1 = dieta C3, sem suplementação de glutamina, e T2 = dieta C3, suplementada com 1% de glutamina. Nos dias 0, 1, 2, 3, 4, 5, 8, 11, 15, 20, 29 e 46 pós-desmame, foram abatidos dois leitões/tratamento. Amostras dos músculos Psoas major e Masseter, fígado e pâncreas foram coletadas e analisadas quanto à composição em d‰13C e mensurada a substituição do carbono em função do tempo. A glutamina acelerou a substituição do carbono em ambos os músculos, como observado pelos valores de meia-vida (T) destes tecidos (T = 51,4 e 21,7 dias para Masseter e 31,5 e 20,3 dias para Psoas major, nos tratamentos sem e com suplementação de glutamina, respectivamente). Os valores de meia-vida do carbono das vísceras indicam que esse aminoácido também acelerou o turnover do carbono nestes órgãos. Os resultados indicam estímulo anabólico da glutamina sobre os tecidos avaliados.The study was carried out to verify the influence of glutamineon carbon turnover in the muscles and viscera of piglets. Nine sows were bred and received diets predominantly composed by grains of C4 photosynthetic cycle plants during gestation and lactation. The piglets were weaned at 21 days of age, and 48 animals were distributed at random in two treatments: T1 = C3 diet, without glutamine supplementation; and T2 = C3 diet, supplemented with 1% glutamine. On days 0, 1, 2, 3, 4, 5, 8, 11, 15, 20, 29 and 46 postweaning, two piglets per treatment were slaughtered. Samples of the Psoas major and Masseter muscles, liver and pancreas were collected and analyzed for d‰13C composition, and carbon turnover was measured as a function of time. It was verified that glutamineaccelerated the carbon turnover in both studied muscles, as observed for the half-life values of these tissues (T = 51.4 and 21.7 days for Masseter, and 31.5 and 20.3 days for Psoas major, in the treatments without and with glutamine supplementation, respectively. The half-life values of the carbon for the liver and pancreas, with and without glutamine treatments, indicate that this amino acid also accelerated the turnover of the carbon in these organs. Theresults indicated anabolic stimulus by glutamine on the evaluated tissues.