Kinetics of Inhibition of Polyphenol Oxidase Obtained from Tobacco Nicotiana Tobacum

In this study, the kinetics of inhibition of polyphenol oxidase by L-cysteine has been investigated. The inhibition of tobacco polyphenol oxidase was studied using the progress-of-substrate-reaction method proposed by Tsou, following the substrate reaction during irreversible inhibition of the enzyme activity. Analysis of the inhibition kinetics shows that inhibition occurs by an irreversible and non-complexation reaction. The microscopic rate constants were determined for reaction of the inhibitor both with the free enzyme and with the enzyme-substrate complex. The results show that the presence of the substrate has a significant protective effect of the enzyme against inactivation by L-cysteine.     

用固定化酶管流动注射测定谷氨酸

用多孔玻璃珠固定自制的谷氨酸氧化酶（GO）制成GO固定化酶管，并结合流动注射系统测定谷氨酸（Glu)的含量，测定的线性范围在0．2－3．0mol/m3，精密度（c.v.)为0．75％，测定速率每小时60个样品，该酶管使用寿命为40d，在一定的条件下，保存稳定期达120天，当测定的Glu浓度低于3mol/m3时，pH在6．5－7．5，温度在20－30度，磷酸盐浓度在0．05－0．25mol/L范围内变化时，对Glu含量的测定几乎无影响，用醋酸纤维膜修饰的铂电极测定H2O2选择性好，该方法与试剂盒法同时测定不同发酵时间发酵液中Glu的含量，两者结果一致。     

Effects of female sex hormones on polyamine-oxidizing enzyme activities and polyamine concentrations in immature rat uterus and liver

17-estradiol (E₂) and progesterone (P) treatment of immature female rats (10 g/100 g body weight) respectively resulted in 1.38-fold (p<0.02) and 1.42-fold (p<0.02) increase in the uterine polyamine oxidase activity, and 2.45-fold (p<0.001) and 1.43-fold (p<0.02) increase in the uterine diamine oxidase activity, as compared to the controls. E₂ caused a 5-fold (p<0.05) and a 1.36-fold (p<0.05) increase in putrescine and spermidine concentration respectively in rat uterus. Increases of 1.7-fold (p<0.02) and 1.6-fold (p<0.05) in putrescine and spermine concentration were determined in the P-treated uterus, as compared to the controls. The spermidine/spermine ratio, which is regarded as an index of growth rate, was higher in the E₂-treated uterus and lower in the P-treated uterus than in the control uterus. No statistically significant hormonal effects were estimated in the immature liver. The data reported suggest the possibility of an involvement of polyamine-oxidizing enzymes in the modulation of polyamine concentrations in rat uterus by the female sex hormones.     

速率法、丙酮酸氧化酶法与微板赖氏法检测ALT的对比试验

目的：为血站筛查ALT选择较准确可靠的试验方法提供试验依据．方法：由内蒙古通辽市中心血站提供的63份ALT含量不同的血浆标本进行速率法（简称S法）、丙酮酸氧化酶法（简称B法）与微板赖氏法（简称L法）比较．结果：L法、S法、B法的中值定值血清（接近血站的判断标准）,板内变异系数依次为7．03％、3．98％、2．47％;L法、S法、B法的中值定值血清板间变异系数依次为7．86％、5．75％、5．50％．结论：微板丙酮酸氧化酶法可以作为血站筛查ALT的方法．     

Involvement of NADPH oxidase NtrbohD in the rapid production of H2O2 induced by ABA in cultured tobacco cell line BY-2

The mechanisms for the production of hydrogen peroxide (H₂O₂) induced by abscisic acid (ABA) were investigated in suspension culture cells of tobacco BY-2 cells. The results showed that the immediate generation of H₂O₂, which was mainly derived from superoxide dismutase-catalyzed dismutation of superoxide radical, was significantly induced by ABA. Furthermore, treatment of the cultured tobacco cells with ABA resulted in a time-dependent quick increase in plasma membrane (PM) NADPH oxidase activity, which coincided on time and magnitude with the elevation in ABA-induced accumulation of H₂O₂. Moreover, these enhanced effects were pronouncedly inhibited by two NADPH oxidase inhibitor, diphenylene iodonium and imidazole, suggesting that PM NADPH oxidase is involved in the rapid accumulation of ₂O₂ in cultured tobacco cells. In addition, analysis of the expression level of NtrbohD, a PM NADPH oxidase gene in tobacco, by RT-PCR and protein gel blot revealed that the gene at both mRNA and protein levels was upregulated by ABA, indicating that NtrbohD participates in the ABA-stimulated rapid production of H₂O₂ in tobacco culture cells. Taken together, these findings suggest that ABA induces the rapid accumulation of reactive oxygen species via NADPH oxidase in suspension culture cells of tobacco, and that NADPH oxidase and H₂O₂ appear to be important components in ABA signal transduction pathway in plants.     

化学发光法检测保健食品中SOD活性的研究

目的：建立保健食品ＳＯＤ活性检测的标准。方法：采用化学发光法测定保健食品（花粉、茶等）中ＳＯＤ活性,及其试验条件的研究。即黄嘌呤氧化酶、次黄嘌呤、鲁咪诺、温度等因素对ＳＯＤ活性测定体系的影响,进行该方法的精密度试验,其ＣＶ（％）为２．３。结果：方法重现性好,灵敏高度,操作简便,检测迅速。结论：是监测ＳＯＤ型保健食品ＳＯＤ活性的可靠方法。     

黄嘌呤氧化酶微型生物传感器及其应用的研究

该文利用Ｎａｆｉｏｎ和电化学聚合苯酚（ＰＰｈ）复合膜将黄嘌呤氧化酶（ＸＯＤ）成功地固定在碳纤维微电极上，制成黄嘌呤氧化酶微型传感器。在５．０×１０－５～１．８×１０－３ｍｏｌ／Ｌ范围内次黄嘌呤浓度与传感器的电流响应呈线性关系，相关系数为０．９９９０。该传感器具有灵敏度高，抗干扰能力强，使用寿命长等特点。传感器用于心肌细胞缺血性损伤过程中胞外次黄嘌呤的测定，结果满意。     

半自然驯化条件下黑线姬鼠冬夏两季产热的比较

为探讨小型哺乳动物适应于季节性环境的产热机制,本文测定了户外半自然条件下驯化的黑线姬鼠(Apodemus agrarius)冬、夏两季的体重以及肝和褐色脂肪组织(Brown adipose tissue, BAT)的细胞色素c氧化酶及BATα-磷酸甘油氧化酶活力等指标.结果显示黑线姬鼠冬季体重显著降低,BAT绝对重量、BAT和肝的线粒体蛋白含量及BAT和肝酶的活力冬季均显著高于夏季.冬季BAT细胞色素c氧化酶活力是夏季的9.5倍,肝脏细胞色素c氧化酶活力是夏季的5倍;冬季BAT的α-磷酸甘油氧化酶活力高达夏季的19倍.以上结果表明,在寒冷的冬季为保证存活,黑线姬鼠降低体重以减少绝对能量需求,并极大地增加BAT重量及肝和BAT细胞水平上的产热能力.     

白花泡桐根分化过程中过氧化物酶、IAA氧化酶和过氧化氢酶的变化

为了解过氧化物酶、IAA氧化酶和氧化氢酶在植物不定根分化,发育过程中的作用,在实验室分析测定白花泡桐[Paulownia foutunei (Seem.)Hemsl]不定根分化过程中过氧化物酶、IAA氧化酶和过氧化氢酶活性的变化。结果表明：过氧化物酶在根分化0d-2d的活性下降37．6％,随后逐步上升;IAA氧化酶活性在0d-2d内迅速下降了52．6％,随后逐步上升;过氧化氢酶的活性在不定根化化过程中逐步上升,0d-4d酶活性从5．1上升到10．5,从第4天开始活性增加减慢。     

Bythinella Moquin-Tandon, 1856 (Gastropoda: Rissooidea: Bythinellidae) in Romania: species richness in a glacial refugium

The buff-throated partridge, Tetraophasis szechenyii Madarász, 1885, is a species endemic to west China. The complete mitochondrial genome of this species was sequenced. It was 16,706 base pairs (bp) in length and contained 13 protein-coding genes, 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a control region (CR). The phylogenetic relationships of the buff-throated partridge and 19 other Phasianidae species were inferred by Bayesian inference and maximum likelihood analyses based on 12 protein-coding genes. With the exception of a few nodes, most internal branches were supported by a high Bayesian posterior probability (BPP?=?1.0). The resulting trees clarified the phylogenetic position of T. szechenyii within Phasianidae. The genetic diversity and population structure of the Pamulin population of T. szechenyii were examined based on the mitochondrial DNA CR. Nucleotide sequence analysis defined 18 haplotypes in 24 individuals. Haplotype diversity (h) was 0.953 and nucleotide diversity (π) was 0.0044. The results revealed that the genetic diversity of this population was not particularly low. Combined with the field work conducted by our lab, we found that members of the Pamuling population are cooperative breeders and the population may contain individuals from neighbouring groups. Our work provided genetic background information for the conservation and management of this species.