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为了探讨育肥羊在饲喂条件下颈静脉灌注13C-苯丙氨酸(13C-Phe)作为指示剂氨基酸进行氨基酸代谢动力学研究时,呼出气13CO2中同位素丰度达到稳定状态的时间及平台期持续时间。选取4只体重32 kg左右哈萨克公羔作为试验动物,代谢笼内单笼饲养。每天按正常采食量的90%(1 200 g)饲喂2次。其中第1~第6天为适应期,第7天为灌注和呼出气的采样期。采集灌注过程中至灌注结束后不同时间点的呼出气样本,测定13C的千分差值,以确定同位素的稳态。结果表明,4只试验羊在饲喂条件下以13C-Phe作为指示氨基酸进行指示氨基酸氧化法(IAAO)测定时,呼出气样品中13C的千分差值在灌注开始后迅速升高,平台期可维持2 h左右,最终确定的13C-Phe的最佳取样时间是在灌注开始后的第1.5~第4 h。本研究结果为今后测定动物对蛋白质和各种氨基酸的需要量奠定了基础。 相似文献
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CP-MAS-13C-NMR Spectra of a Lithic Cryofolist CP-MAS-13C-NMR spectra of the organic layers of a lithic cryofolist show typical changes during litter decomposition and humification. Peaks due to alkyl-C (mainly polymethylene) and carboxyl-C increase, those due to ether-C (carbohydrates), acetal-C and aromatic-C decrease. These results are in agreement with the results obtained from conventional extractive techniques. The aliphatic character is far more pronounced than the aromatic one. 相似文献
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陇糜13号是2003年以会宁大黄糜为母本,以系选优系8711-1-3-2-2为父本进行有性杂交,经过多年水旱穿梭选育和多点鉴定,育成的高产稳产糜子新品种。生育期117～126 d,平均株高165.4 cm,穗长35.2 cm,茎粗0.60 cm,主茎可见节数7.1节,株有效穗数1.0个,单株穗重9.29 g,单穗粒重6.34 g,千粒重8.0 g,单株草重14.28 g,出谷率68.25%。黄米水分含量10.61%(干基)、粗蛋白含量178 g/kg(干基)、粗脂肪含量40.3 g/kg(干基)、粗淀粉含量739.1 g/kg(干基)、赖氨酸含量3.6 g/kg(干基)、铁含量75.5 mg/kg(干基)。在甘肃省多点区域试验中,陇糜13号2 a 14点(次)折合产量3 814.95 kg/hm2,较对照品种陇糜10号增产12.27%。人工接种鉴定,黑穗病发病株率2.01%,表现高抗黑穗病。适宜在甘肃省庆阳、平凉、白银、定西等地及其相似生态区海拔1 650～ 1 900 m的地区春播、海拔1 200～1 400 m的地区复种。 相似文献
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Ten newly isolated hop proanthocyanidin oligomers and flavan-3-ol monomers from 13 different hops have been identified as gallocatechin, gallocatechin-(4alpha-->8)-catechin, gallocatechin-(4alpha-->6)-catechin, catechin-(4alpha-->8)-gallocatechin, catechin-(4alpha-->6)-gallocatechin, afzelechin-(4alpha-->8)-catechin, catechin-(4alpha-->8)-catechin-(4alpha-->8)-catechin, epicatechin-(4beta-->8)-epicatechin-(4beta-->8)-catechin, catechin-(4alpha-->8)-gallocatechin-(4alpha-->8)-catechin, and gallocatechin-(4alpha-->8)-gallocatechin-(4alpha-->8)-catechin, together with seven previously isolated oligomers, namely, catechin, epicatechin, epicatechin-(4beta-->8)-catechin, epicatechin-(4beta-->8)-epicatechin, catechin-(4alpha-->8)-catechin, catechin-(4alpha-->8)-epicatechin, and epicatechin-(4beta-->8)-catechin-(4alpha-->8)-catechin. These compounds were subjected to acid-catalyzed degradation in the presence of phloroglucinol or by partial or complete acid-catalyzed degradation and reaction with benzyl mercaptan followed by desulfurization. The resultant adducts when compared to authentic samples by high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry and high-performance liquid chromatography-electrospray ionization tandem mass spectrometry served to identify the precursors. The composition of proanthocyanidins from 13 different hops was similar, but the concentration of individual compounds showed some differences, which indicated that hop proanthocyanidin profiles are affected by geographic origin and are variable depending on the cultivars. 相似文献
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Sitohy M Chobert JM Karwowska U Gozdzicka-Jozefiak A Haertlé T 《Journal of agricultural and food chemistry》2006,54(11):3800-3806
Esterified milk proteins [methylated (Met) or ethylated (Et) alpha-lactalbumin (ALA), beta-lactoglobulin (BLG), and beta-casein (BCN)], unmodified native milk proteins, and native basic proteins (calf thymus histone and hen egg white lysozyme) were tested for their antiviral activity against the bacteriophage M13 and for their influence on its replication (except BCN). All esterified milk proteins showed an antiviral activity against the bacteriophage M13, proportional to the extent of esterification and, hence, to the increased basicity of the modified proteins. Antiviral activity of 100% Met-BLG disappeared after its pepsinolysis but not after its trypsinolysis. The antiviral activity of Met-BLG was much higher than that of native basic proteins (histone and lysozyme). One hundred percent Met-BLG and 73% Et-BLG inhibited the replication of bacteriophage M13 completely, whereas 60% Met-ALA inhibited phage replication partially. Calf thymus histone inhibited the replication of bacteriophage M13 at a lower extent (20%) than Met- and Et-BLG (100% inhibition). Protein concentration, pH, and concentration of the Escherichia coli culture in the preincubation medium of the virus were other factors influencing antiviral activity. Interactions of esterified proteins with the phage DNA (phenol extracted) followed the same pattern as observed during studies of the inhibition of the phage replication: Met-BLG > Et-BLG > or = Met-ALA. 相似文献
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Banijamali AR Xu Y Strunk RJ Gay MH Ellis MC Putterman GJ Sumner SJ 《Journal of agricultural and food chemistry》1999,47(4):1717-1729
Little is known about the metabolism of acetylenic (C&tbd1;C) compounds commonly used in the formulation of pesticides. To better understand the in vivo reactivity of this bond, we examined the metabolism of propargyl alcohol (PA), 2-propyn-1-ol, used extensively in the chemical industry. [1,2,3-(13)C, 2,3-(14)C]PA was administered orally to male Sprague-Dawley rats. Approximately 56% of the dose was excreted in urine by 96 h. Major metabolites were characterized, directly, in the whole urine by one- and two-dimensional (13)C NMR. To determine the complete structures of metabolites of PA, rat urine was also subjected to TLC followed by purification of separated TLC bands on HPLC. The purified metabolites were identified by (13)C NMR and mass spectrometry and by comparison with available synthetic standards. The proposed metabolic pathway involves oxidation of propargyl alcohol to 2-propynoic acid and further detoxification via glutathione conjugation to yield as final products: 3, 3-bis[(2-(acetylamino)-2-carboxyethyl)thio]-1-propanol, 3-(carboxymethylthio)-2-propenoic acid, 3-(methylsulfinyl)-2-(methylthio)-2-propenoic acid, 3-[[2-(acetylamino)-2-carboxyethyl]thio]-3-[(2-amino-2-carboxyethyl)t hio]-1-propanol and 3-[[2-(acetylamino)-2-carboxyethyl]sulfinyl]-3-[2-(acetylamino)-2-car boxyethyl]thio]-1-propanol. These unique metabolites have not been reported previously and represent the first example of multiple glutathione additions to the carbon-carbon triple bond. 相似文献
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We conducted a 13CO2 pulse-chase labelling experiment in a drained boreal organic (peat) soil cultivated with perennial crop, reed canary grass (RCG; Phalaris arundinacea) to study the flow of carbon from plants to soil microbes. Both limed and unlimed soils were studied, since liming is a common agricultural practice for acidic organic soils. Soil samples taken within three months after the labelling and three times in the following year were used for the δ13C analysis of microbial phospholipid fatty acids (PLFAs), root sugars and root lipids. We estimated the contribution of carbon from root exudates to microbial PLFA synthesis. The flow of carbon from plants to microbes was fast as the label allocation in PLFAs had a peak 1–3 days after labelling. The results showed that fungi were important in the incorporation of fresh, plant-derived carbon, including root sugars. None of the main microbial PLFA biomarker groups (fungi, Gram-positive bacteria, Gram-negative bacteria, arbuscular mycorrhizal fungi) was completely lacking label over the measurement period. One year after the labelling, when the labelled carbon was widely distributed into plant biomass and soil, bacterial biomarkers increased their share of the label allocation. Liming had a minor effect on the label allocation rate into PLFAs. The mixing model approach used to calculate the root exudate contribution to microbial biomass resulted in a highly conservative estimate of utilization of this important C-source (0–6.5%, with highest incorporation into fungi). In summary, the results of this study provide new information about the role of various microbial groups in the turnover of plant-derived, fresh carbon in boreal organic soil. 相似文献
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Analysis of the pyrolysis products of [1-(13)C], [2-(13)C], and [3-(13)C]-labeled L-serines has indicated the presence of three initial degradation pathways. Decarboxylation followed by deamination produces aminoethanol and acetaldehyde, respectively; a retro-aldol pathway generates formaldehyde and glycine. Dehydration of L-serine can lead to the formation of pyruvic acid, which eventually can be converted into the amino acid alanine. Formation of alanine and glycine was confirmed due to the detection of 2, 5-diketo-3,6-dimethylpiperazine and cycloglycylalanine. Most of the advanced decomposition products of L-serine can be rationalized on the basis of these initial degradation products. Label incorporation studies have elucidated the origin of carbonyl precursors of methyl- and 2,3-dimethylpyrazines formed in the thermal decomposition mixture of L-serine. Three mechanistic pathways were identified for the formation of carbonyl precursors of methyl- and 2, 3-dimethylpyrazines. The major pathway (70%) for the formation of the precursor of methylpyrazine involved aldol addition of formaldehyde to glycolaldehyde to form glyceraldehyde. On the other hand, the major pathway (60%) for the formation of the precursor of 2,3-dimethylpyrazine involved an aldol condensation of acetaldehyde with glycolaldehyde to form 2,3-butanedione. 相似文献
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Palomino-Schätzlein M Escrig PV Boira H Primo J Pineda-Lucena A Cabedo N 《Journal of agricultural and food chemistry》2011,59(21):11407-11416
(13)C nuclear magnetic resonance (NMR) spectroscopy was explored as a simple and efficient technique for the quantitative analysis of nonpolar metabolites in plants. The method was first optimized with a mixture of known metabolites and then applied to the nonpolar leaf extracts of plants harvested in the Valencian community (eastern Spain) belonging to three different genera: Euphorbia (Euphorbiaceae), Araujia (Apocynaceae), and Morus (Moraceae). Furthermore, an exhaustive analysis of Euphorbia characias leaf and stem extracts from different geographic locations allowed that quantitative (13)C NMR spectroscopy is a suitable tool for metabolic profiling purpose. 相似文献