丝瓜种子萌芽及子叶生长过程中谷氨酰胺合成酶同工酶的变化

测定了丝瓜种子萌芽及子叶不同生长阶段的谷氨酰胺合成酶(GS)的活性及其同工酶的变化．除了发育上的变化外，光和外源氮对GS活性及其同工酶影响也是显著的．无论外源氮(N)是否存在，GS活性在种子萌芽和子叶生长初期是逐渐升高的，于第6天达到最大，其后活性逐步降低．在光照下，外源氮对GS1诱导作用大于GS2；在无氮下，光对GS2的刺激大于GS1；在暗处，外源氮对GS1和GS2两者都有诱导作用．     

Simultaneous measurement of glucose and glutamine in aqueous solutions by near infrared spectroscopy

A method is described for measuring the concentrations of both glucose and glutamine in binary mixtures from near infrared (NIR) absorption spectra. Spectra are collected over the range from 5000–4000/cm (2.0–2.5μm) with a 1-mm optical path length. Glucose absorbance features at 4710, 4400, and 4300/cm and glutamine features at 4700, 4580, and 4390/cm provide the analytical information required for the measurement. Multivariate calibration models are generated by using partial least squares (PLS) regression alone and PLS regression combined with a preprocessing digital Fourier filtering step. The ideal number of PLS factors and spectral range are identified separately for each analyte. In addition, the optimum Fourier filter parameters are established for both compounds. The best overall analytical performance is obtained by combining Fourier filtering and PLS regression. Glucose measurements are established over the concentration range from 1.66–59.91 mM, with a standard error of prediction (SEP) of 0.32 mM and a mean percent error of 1.84%. Glutamine can be measured over the concentration range from 1.10–30.65 mM with a SEP of 0.75 mM and a mean percent error of 6.67%. These results demonstrate the analytical utility of NIR spectroscopy for monitoring glucose and glutamine levels in mammalian and insect cell cultures.     

谷氨酸钠从其水溶液中的周期结晶现象

早在本世纪初物理化学家们就已观察到，某些物质从其熔融态或溶液中结晶出来时，在某些条件下可形成周期性的宏观结晶条纹［1，2］，这就是周期结晶现象，由于这种现象和晶体生长、材料物性以及成矿过程等重要问题紧密相关，很早就引起了人们的重视．近年来有关非平衡非线性系统中自发产生各种时空有序现象（自组织现象）的各种理论（如耗散结构理论）［3］的兴起，重新引起了人们对这类现象的兴趣．八十年代，Iwamoto等先后报道了甲基苄基氨基甲酸酯（MethylMesitylcarbamate）从氯仿溶液［4］和抗坏血酸（AscorbicAcid）从甲醇溶液［5］…     

满江红鱼腥藻glnA基因上游调控区的克隆及其序列分析

以满江红鱼腥藻（Ａａｃ）提取总ＤＮＡ为模板,通过ＰＣＲ技术,扩增得到其谷氨酰胺合成酶基因（ｇｌｎＡ）上游区．经酶切得到４０９ｂｐ的片段,并将其连接到ｐＢｌｕｅｓｃｒｉｐｔⅡｋｓ＋上测序．将测序结果与Ａｎａｂａｅｎａ７１２０调控序列比较,有９８２％的同源性．在上游调控中也具有ｎｉｆｌｉｋｅ和Ｅ．ｃｏｌｉｌｉｋｅ启动子,值得注意的是,调节蛋白ＶＦ１的结合位点正好位于ｎｉｆｌｉｋｅ启动子上．所克隆的片段不但对蓝藻固氮、泌氨的基因调控研究具有意义,也对表达载体的构建具有实用价值．     

ALLOSTERIC REGULATION OF THE STATE OF ADENYLYLATION OF GLUTAMINE SYNTHETASE IN PERMEABILIZED CELL PREPARATIONS OF Rhoaopseudomonas sphaeroides

Following a freeze-thaw cycle, and the treatment of Rhodopseudomonas sphaeroides withthe nonionic detergent Lubrol PX, the permeabilized cell suspensions can be assayed directlyboth for the intracellular levels of glutamine synthetase and the state of adenylylation(i.e. the average number n of adenylylated subunits/dodecameric molecules). It seems that all components of the bicycle system are retained if cells grown with lowconcentrations of a?monia as the sole nitrogen source are used. The value of n was depend-ent upon the concentration of substrates (ATP, Pi) and allosteric effectors (ATP, gluta-mine and α-ketoglutarate) of adenylyltransferase. The value of n affected by UTP, thespecific substrate of the uridylyltransferase shows first the evidence that the bicycle cascadecontrol system studied in Escherichia coli may exist in this phototrophic bacterium.     

丙氨酰-谷氨酰胺的简便有效合成

谷氨酰胺 (Ｇｌｎ)是肠道必需氨基酸 ,是肠粘膜细胞氧化的重要燃料。肠粘膜缺乏Ｇｌｎ将严重损伤肠屏障功能 ,创伤性休克及化疗应激可加重损害 ,导致肠粘膜萎缩 ,肠道细菌移位 ,甚至促发脓毒症和多器官功能不全 (ＭＯＤＳ) [1] 。但Ｇｌｎ性质不稳定 ,不能耐高温消毒 ,因此 ,一般氨基酸制剂不含Ｇｌｎ。Ａｌａ Ｇｌｎ为Ｇｌｎ代谢前体 ,溶解度高 ,性质较Ｇｌｎ稳定 ,能耐受热灭菌 ,在体内数分钟即分解出Ｇｌｎ ,能部分补偿肠道所需Ｇｌｎ ,减少严重创伤及腹腔注射化疗药物 5 氟尿嘧啶 (5 ＦＵ)引发的小肠粘膜形态功能改变 ,细菌移位 ,降低…     

Growth inhibition in animal cell culture

Eight independent cell lines accumulated ammonia in culture to concentrations between 1.3 and 2.9 mM. The growth inhibition of such concentrations of ammonium chloride when added to culture medium was variable. The cell lines tested could be divided into 3 groups depending on their growth response to 2 mM added NH4Cl. In the first group (293, HDF, Vero, and PQXB1/2) little (less than 14%) or no growth inhibition occurred. In the second group (McCoy and MDCK) a reduction in final cell yield of 50-60% was observed. The third group (HeLa and BHK) was most sensitive to the effects of NH4Cl with growth inhibition (greater than 75%) compared to controls. The growth inhibitory effect of added lactate up to 20 mM was negligible (less than 10%) for 3 cell lines, although one cell line (PQXB1/2) showed greater sensitivity. The interactive effects of ammonia and lactate were determined in a matrix experiment. At lactate (greater than 12 mM) and ammonia (1-4 mM), the growth inhibitory effects of the two components were synergistic. However, at low concentrations of lactate (less than 12 mM) the toxic effect of ammonia was reduced. A proposed mechanism for the sparing effect of lactate on ammonia toxicity is discussed. This may have importance in developing strategies for the optimal growth of ammonia-sensitive cell lines.     

谷氨酰胺的代谢特点与运动营养

谷氨酰胺是体内一种条件性必需氨基酸，对于人体的运动能力和免疫功能均有着较大的影响。不同运动形式下，GLU的代谢特点也会发生不同的变化。GLU还是免疫系统的重要代谢底物，其含量的下降将会导致器官损伤、免疫机能下降。因此，在运动员的营养研究中，对GLU的研究较多，这里对之做一综述，以更好地掌握和了解GLU代谢与运动的关系。     

胰岛素抵抗及高血糖对GFAT活性的影响

分别观察了胰岛素抵抗和高血糖水平对己糖胺途径限速酶GFAT活性的影响.在alloxan高血糖小鼠模型中,与正常对照组比较,血清果糖胺水平升高了15.9%,肾组织GFAT活性升高了32.8%;经胰岛素治疗后,血清果糖胺水平降低了9.7%,其肾组织GFAT活性也降低了l9.4%.在高糖高脂饲料诱导的胰岛素抵抗的IR小鼠中,与同批正常对照组比较,正糖钳实验中稳态时葡萄糖输注率G IR值降低了69.3%,胰岛素耐量实验中的AUC值升高了38.1%,其肾脏组织GFAT活性也增加了26.6%.在胰岛素诱导的具有胰岛素抵抗的IR-H IR c细胞模型中,与正常H IR c细胞比较,其10、25 nmol/L胰岛素诱导的葡萄糖摄取能力分别降低了25.3%、21.1%,而GFAT活性分别增加了29.7%、46.5%.可见,GFAT活性与一段时间的平均血糖水平和胰岛素抵抗状态密切正相关.     

Metabolic Profiling of Amino Acids by Liquid Chromatography–Tandem Mass Spectrometry (LC–MS) to Characterize the Significance of Glutamine in Triple-Negative Breast Cancer (TNBC)

Triple-negative breast cancer (TNBC) is considered to be aggressive based on its low overall survival and disease-free rates. Currently, there is no molecular-targeted therapy. The identification of a suitable biomarker is still a research focus for TNBC at the present time. Amino acid metabolism fulfills multiple important physiological roles in humans. Their metabolic abnormalities have been reported in numerous cancer studies and amino acid pathways may also be chemotherapeutic targets. This study reports the profiling analysis of amino acids in TNBC and non-TNBC cell lines for detecting biomarkers based on the strategy of N-phosphorylation labeling with liquid chromatography–tandem mass spectrometry (LC–MS). Glutamine (Gln) was found to be significantly down-regulated in TNBC cells because it was largely absorbed and consumed in the TNBC cell lines. These results indicate faster proliferation of TNBC and higher consumption of glutamine to meet the material and energy demand, suggesting its potential role in TNBC progression. Hence, glutamine may be regarded as a biomarker and Gln-targeted approaches may become a new therapeutic strategies for TNBC.