Clausthal, Techn. Univ., Diss., 2005. / Computerdatei im Fernzugriff.

Clausthal, Techn. University, Diss., 2005.

No description available.

Phosphatidylethanolamine (PE) is an important inner membrane phospholipid synthesized de novo by the CDP-ethanolamine pathway and by the decarboxylation of phosphatidylserine. CTP: phosphoethanolamine cytidylyltransferase (Pcyt2) is the main regulatory enzyme in the CDP-ethanolamine pathway and catalyzes the formation of CDP-ethanolamine from phosphoethanolamine. Complete deletion of the mouse Pcyt2 gene is embryonic lethal, and the single allele deficiency leads to development of metabolic syndrome phenotype, including liver steatosis, hypertriglyceridemia, obesity, and insulin resistance. This study aimed to specifically elucidate the effects of dietary methyl group donors betaine and choline supplementation in Pcyt2 heterozygous mice (ETKO). Evidence here shows choline and its oxidized metabolite betaine are responsible for lowering whole body weight, restoring insulin resistance, reducing hypertriglyceridemia, hepatic steatosis, and alleviating adipose and liver tissue inflammation, by restoring hepatic metabolism and gene expression. Collectively, these results establish that the impaired systemic metabolism resulting from Pcyt2 deficiency is a metabolic adaptation that is restored after methyl group supplementation.

Universiẗat, Diss., 1999--Kaiserslautern.

Resumo: Três experimentos foram conduzidos com linhagens comerciais de frangos de corte em baterias metálicas para determinar a biodisponibilidade relativa de duas fontes de grupamentos metílicos (metionina e betaína). A dieta basal (controle) foi formulada com milho e farelo de soja, contendo 1.896, 1.969 e 2.010 mg/kg de colina no experimento I, II e III, respectivamente. Os níveis suplementados em betaína e metionina foram isomolar. O experimento I (fêmeas até 21 dias de idade) constou de seis níveis de metionina (0; 5,36; 10,72; 16,08; 21,45; 32,17 mMol/kg) e dois níveis de betaína (0 e 5.36 mMol/kg). No experimento II (machos até 21 dias de idade) a dieta controle foi suplementada com 0; 2,68; 5,36; 8,04; 10,72; 13,40 mMol/kg de metionina ou 0; 2,68; 5,36; 8,04; 10,72; 13,40 mMol/kg de betaína. Em relação ao experimento III (machos até 21 anos de idade) houve quatro níveis de metionina (0; 8,04; 10,72 e 13,40 mMol) e três níveis de betaína (0; 6,7 e 13,4 mMol). Para o experimento I e III foram utilizados quatro repetições de oito aves para cada tratamento. O experimento II apresentou quatro repetições para cada tratamento e oito repetições para o grupo controle, apresentando também oito aves por parcela experimental. Foi constatado para os experimentos I, II e III que os valores de inclinação da curva pra a betaína e metionina foram significativos para o peso corporal e conversão alimentar. No experimento III somente o valor de inclinação para a curva da metionina foi significativo, em relação ao consumo alimentar. No experimento III somente o valor de inclinação para a curva da metionina foi significativo, em relação ao consumo alimentar. Nem a metionina ou a betaína diminuíram a gordura abdominal em nenhum dos experimentos. Em média, os dados do experimento II e III indicaram que a biodisponibilidade relativa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Three experiments were conducted with commercial strain chickens in battery brooders to determine the relative bioavailability of the two methyl sources (methionine and betaine). For basal corn and soybean mean based died contained 1,896, 1,969 and 2,010 mg/kg choline in Experiment I, II and III, respectively. Betaine and methionine supplements were isomolar. In Eexperiment I (females for 21 days) there were 6 levels of methionine (0; 5.36; 10.72; 16.08; 21.45; 32.17 mMol/kg) and two levels of betaine (0 and 5.36 mMol/kg). In Experiment II (male for 21 days) the control diets were supplemented with 0; 2.68; 5.36; 8.04; 10.72; 13.40 mMol / kg methionine or 0; 2.68; 5.36; 8.04; 10.72; 13.40 mMol/kg betaine. In Experiment III (male 21 days) there were 4 levels of methionine (0; 8.04; 10.72 and 13.40 mMol) and three levels of betaine (0; 6.7 and 13.4 mMol) .There were four replicate pens with eight chicks per each treatment in Experiment I and III. There were four replicates per each treatment and eight replicates pens for the control group in Experiment II. In Experiment I, II and III, the slope values for betaine and methionine were significant on body weight gain and feed conversion. In Experiment III, only for methionine, the slope values were significant on feed consumed. Neither methionine nor betaine decreased abdominal fat pad in anyone experiment. On average, the data the experiment II and III indicate that the relative... (Complete abstract click electronic access below)

The role of the labile methyl groups of betaine in the transmethylation reactions in the barley plants was investigated using carbon-14 methyl labelled betaine. The N-methyl groups of N-methyl tyramine, hordenine and choline were found to arise from betaine. Betaine was also administered to castor bean seedlings and the alka­loid ricinine isolated. It was found that its N- and 0-mthyl groups did not arise from betaine methyl. The origin of the methylenedioxy and N-methyl groups of the alkaloid protopine was also investigated by the tracer technique. Carbon-14 methyl labelled L-methionine, carbon-14 labelled choline and carbon-14 labelled sodium formate were fed to Dicentra species and the extent and position of labelling of the protopine molecule determined by degradation / Thesis / Master of Science (MS)

The role of the labile methyl groups of betaine in the transmethylation reactions in the barley plants was investigated using carbon-14 methyl labelled betaine. The N-methyl groups of N-methyl tyramine, hordenine and choline were found to arise from betaine. Betaine was also administered to castor bean seedlings and the alkaloid ricinine Isolated. It was found that Its N- and 0- methyl groups did not arise from betaine methyl. The origin of the methylenedioxy and N-methyl groups of the alkaloid protopine was also investigated by the tracer technique. Carbon-14 methyl labelled L- methionine, carbon-14 methyl labelled choline and carbon- 14 labelled sodium formate were fed to Dicentra species and the extent and position of labelling of the protopine molecule determined by degradation / Thesis / Master of Science (MS)

No description available.

The compatible solute glycine betaine accumulates in many plants including spinach (Spinacea oleracea) under conditions of water deficit stress. The precursor to glycine betaine is choline, a ubiquitous metabolite in plants as a component of phosphotidylcholine. In spinach choline is synthesized from phosphocholine, a product of three sequential N-methylations of phosphoethanolamine catalysed by the cytosolic enzyme S-adenosyl-L-methionine: phosphoethanolamine-N-methyltransferase (PEAMT). PEAMT activity shows diurnal changes with peak activity at the end of the photoperiod and a decrease overnight. The activity of this enzyme is up-regulated 2 to 3-fold in salt-stressed plants relative to unstressed plants. The objective of this thesis is to determine how PEAMT activity is regulated in vivo. Thus, PEAMT activity, protein and transcript levels were quantified in spinach leaves from plants subjected to different light and salinity conditions. A spinach PEAMT eDNA sequence was used to over-express recombinant PEAMT in the protein expression vector pET30a (+). The presence of a polyhistidine-tag on the overexpressed protein allowed for purification by a cobalt metal affinity column. The affinity purified protein was used to produce polyclonal antibodies for immunoblot hybridization analysis. For these studies, PEAMT protein was first immunoaffinity purified from soluble extracts prepared from leaves and then the protein subjected to electrophoresis by SDS-p AGE. Enzyme assays and immunoblot analysis show PEAMT activity and protein levels increase and become relatively constant in leaves of plants exposed to continuous light. In continuous darkness, PEAMT activity and protein levels decrease and remain low and constant. Thus the pattern of changes in PEAMT activity levels are associated with changes in PEAMT protein levels. In contrast, Northern blot hybridizations show that under conditions of constant light, peamt transcript levels undergo cyclical changes with peak levels at 20 and 40 h and troughs at 28 and 52 h after the continuous light treatment was imposed. These peaks coincide with the dark and light cycles of the normal photoperiod. The same cyclical changes in peamt transcript levels was seen for plants transferred from a normal photoperiod to continuous darkness. Since these changes persist in the absence of a day/night cue we conclude that peamt transcript levels are circadian-regulated. The peamt transcript levels of control unstressed and salt-stressed plants also show circadian rhythms, however the levels found in salt-stressed plants were 0.5 to 2-fold higher than the controls. Therefore, while salinization of plants increases peamt transcript abundance, it does not alter the circadian rhythm that transcripts of this gene display. Changes in PEAMT activity and protein levels are likely controlled by other as yet unknown post-translational mechanisms, processes that override and obscure operation of a circadian rhythm in regulating the level of peamt transcripts. / Thesis / Master of Science (MS)