Candida utilis生物合成谷胱甘肽的营养及环境条件

研究了摇瓶条件下Candida utilis WSH02—08生物合成谷胱甘肽(GSH)的营养条件，确定以葡萄糖作为碳源，硫酸铵和尿素作为混合氮源．在L6(4^5)正交试验的基础上，选用BP神经网络对营养条件进行优化和预测，得出较优的营养组合为：葡萄糖30gL^-1(NH4)2SO4gL^-1，尿素4gL^-1，KH2PO4 3gL^-1，MgSO4 0．25gL^-1．研究了GSH发酵的环境条件，得出较优的组合为：初始pH6．0，装液量30mL／250mL，接种量10％．利用优化后的营养及环境条件进行摇瓶发酵实验，结果表明，GSH产量和细胞干重均有较大幅度的提高．图7表2参13     

In vitro Methylation of Arsenite in Flemish giant rabbit Cytosol

The formation of ⁷⁴As‐monomethyIarsonic acid and ⁷⁴As‐dimethylarsinic acid from carrier‐free radiolabelled ⁷⁴As‐arsenite was evaluated in an assay mixture containing 17.6% liver cytosol from the Flemish Giant rabbit. The optimal incubation temperature and pH were respectively, 39°C and 7.6. After a 2h incubation about 90% of ⁷⁴As was protein bound. Protein bound ⁷⁴As was released by hot 2 M HNO₃ (1 min, 110°C). The treatment did not destroy methylated As‐species. Up to 70% of the carrier‐free ⁷⁴As‐arsenite was methylated. Liver cytosol was stored, without loss of activity, in liquid nitrogen in the presence of 2 mM glutathione. The optimal s‐adenosyl‐methionine concentration was 1.7mM. Formation of ⁷⁴As‐monomethylarsonic acid and ⁷⁴As‐dimethylarsinic acid increased up to a glutathione concentration of respectively 10 and 20 mM. Methylation also went through in the presence of other reducing agents and proved to be ATP dependent.     

Effects of herbicide stress on wheat cultivars from organic and conventional cropping systems

Abstract

Wheat (Triticum aestivum L.) seedlings grown from seeds produced in “organic”; (non‐chemical) and “conventional”; cropping systems are characterized by a) similar rates of root and shoot growth, b) equal sensitivity to phytotoxicity by the herbicide glyphosate, and c) equivalent basal activity of the enzyme glutathione S‐transferase (both in the roots and in the shoots). In addition, treatment of these seedlings with glyphosate leads to significantly higher contents of this enzyme both in the shoots and in the roots. However, time‐course and dose‐response investigations indicate significant differences in the induction pattern of glutathione S‐transferase: the response of “conventional”; wheat seedlings takes place earlier and with higher efficiency, than that of the “organic”; ones.     

Brassinosteroid alleviates phenanthrene and pyrene phytotoxicity by increasing detoxification activity and photosynthesis in tomato

The present study was carried out to investigate the effects of exogenously applied 24-epibrassinolide (BR) on growth, gas exchange, chlorophyll fluorescence characteristics, lipid peroxidation and antioxidant systems of tomato seedlings grown under different levels (0, 10, 30, 100 and 300 μM) of phenanthrene (PHE) and pyrene (PYR) in hydroponics. A concentration-dependent decrease in growth, photosynthetic pigment contents, net photosynthetic rate (Pn), stomatal conductance (Gs), maximal quantum yield of PSII (Fv/Fm), effective quantum yield of PSII (Φ_PSII), photochemical quenching coefficient (qP) has been observed following PHE and PYR exposure. By contrast, non-photochemical quenching coefficient (NPQ) was increased. PHE was found to induce higher stress than PYR. However, foliar or root application of BR (50 nM and 5 nM, respectively) alleviated all those depressions with a sharp improvement in the activity of photosynthetic machinery. The activities of guaicol peroxidase (GPOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) as well as content of malondialdehyde (MDA) were increased in a dose-dependent manner under PHE or PYR treatments. Compared with control the highest increments of GPOD, CAT, APX, GR and MDA by PHE/PYR alone treatments were observed following 300 μM concentration, which were 67%, 87%, 53%, 95% and 74% by PHE and 42%, 53%, 30%, 86% and 62% by PYR, respectively. In addition, both reduced glutathione (GSH) and oxidized glutathione (GSSG) were induced by PHE or PYR. Interestingly, BR application in either form further increased enzymatic and non enzymatic antioxidants in tomato roots treated with PHE or PYR. Our results suggest that BR has an anti-stress effect on tomato seedlings contaminated with PHE or PYR and this effect is mainly attributed by increased detoxification activity.     

Oral administration of potassium bromate, a major water disinfection by-product, induces oxidative stress and impairs the antioxidant power of rat blood

Potassium bromate (KBrO₃) is a widely used food additive, a water disinfection by-product and a known nephrotoxic agent. The effect of KBrO₃ on rat blood, especially on the anti-oxidant defense system, was studied in this work. Animals were given a single oral dose of KBrO₃ (100 mg/kg body weight) and sacrificed 12, 24, 48, 96 and 168 h after this treatment. Blood was collected from the animals and separated into plasma and erythrocytes. KBrO₃ administration resulted in increased lipid peroxidation, protein oxidation, hydrogen peroxide levels and decreased the reduced glutathione content indicating the induction of oxidative stress in blood. Methemoglobin levels and methemoglobin reductase activity were significantly increased while the total anti-oxidant power was greatly reduced upon KBrO₃ treatment. Nitric oxide levels were enhanced while vitamin C concentration decreased in KBrO₃ treated animals. The activities of major anti-oxidant enzymes were also altered upon KBrO₃ treatment. The maximum changes in all these parameters were 48 h after the administration of KBrO₃ and then recovery took place. These results show for the first time that KBrO₃ induces oxidative stress in blood and impairs the anti-oxidant defense system. Thus impairment in the anti-oxidant power and alterations in the activities of major anti-oxidant enzymes may play an important role in mediating the toxic effects of KBrO₃ in the rat blood. The study of such biochemical events in blood will help elucidate the molecular mechanism of action of KBrO₃ and also for devising methods to overcome its toxic effects.     

酿酒酵母提取物对废天然橡胶再生的研究

酿酒酵母R1在5L发酵罐中培养36h时,胞内谷胱甘肽(GSH)总量达304mg/L。将酵母菌充分裂解,提取物与废天然橡胶共反应。通过单因素对比实验,确定最适宜的反应条件如下:温度50℃,时间4h,100g胶粉,溶剂用量1.85mol,相转移催化剂用量2.75×10-2mol,酵母菌用量相当于GSH1.0g。处理后最高溶胀度为4.37,是原来的1.49倍。     

固定化多环芳烃降解酶——谷胱甘肽S-转移酶的研究

以自制壳聚糖为载体,戊二醛为交联剂固定谷胱甘肽S-转移酶,研究了交联剂浓度、酶用量、pH值、温度及时间等因素对固定化酶活性的影响.结果表明,戊二醛浓度0.5%,pH7.0,温度20℃,时间12h以及液态酶与壳聚糖凝胶1:1配比是谷胱甘肽S-转移酶最佳固定化条件,固定化酶催化菲降解的最佳反应时间是9h.另外,固定化酶与游离酶相比,稳定性和可操作性都有较大的提高.     

The Use of Mytilus Galloprovincialis Acetylcholinesterase and Glutathione S-Transferases Activities as Biomarkers of Environmental Contamination Along the Northwest Portuguese Coast

With the aim of using Mytilus galloprovincialis acetylcholinesterase (AChE) and glutathione S-transferases (GST) activities as biomarkers of environmental contamination in risk assessment studies along the northwest Portuguese coast, the objective of this study was to provide background information related to: (1) baseline values of these enzymatic activities both in reference and contaminated areas and their responsiveness as indicators of exposure to environmental contaminants; (2) the importance of seasonal variations of such biomarkers in M. galloprovincialis along this area. For this, the activity of these enzymes was seasonally determined in mussels collected from four sites, including a reference and three stations with different contamination sources along the referred area. Statistically significant differences on both enzymatic activities were found among the four sampling stations, at the four sampling periods. In comparison to the reference station, lower AChE and higher GST activity values were found in mussels collected in stations potentially contaminated by pesticides and domestic/industrial effluents and in mussels collected in the vicinity of an oil refinery and an industrial/mercantile harbour, respectively. The results obtained in this work highlighted the potential suitability of these biomarkers to be used as components of environmental monitoring programs in risk assessment studies along the northwest Portuguese coast. Since a seasonal variation in both enzymatic activities was found, the possible implications of such variability in the use of these enzymes as environmental biomarkers are also discussed.     

Glutathione Related Enzyme Levels of Freshwater Fish as Bioindicators of Pollution

The livers and kidneys of freshwater fish species, Oreochromis niloticus and Clarias lazera, collected from sewage polluted sites (Ismailia and El-Bahr El-Azam) and industrial polluted sites (Shubra and El-Tebin) of Nile River were analyzed for different antioxidant defense enzymes. The liver and kidney glutathione transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GPx) were higher in O. niloticus captured from all the polluted areas compared to the control. Low GST activities were found in 33.3%, 60% and 53% in the livers and 100%, 80% and 53% in the kidneys of C. lazera captured from El-Bahr El-Azam, Shubra and El-Tebin. GR and GPx activities increased in livers and kidneys of C. lazera collected from all areas except for Shubra, in which, GPx of livers and kidneys were low in 100% of C. lazera. Metals Ni, Co, Cr, Se, Cd and Pb resulting from industrial wastes and metal mining wastes were enhanced at the polluted sites. SDS-PAGE of liver and kidney of O. niloticus and C. lazera indicated the increase in bands number and intensity of protein bands with subunit molecular weights between 30–20 KDa in polluted areas. Several enzymes from glutathione system (activity and protein) constitute a sensitive biochemical indicator of chemical pollution. Relative changes of glutathione-dependent enzymes in both fish species suggest a different susceptibility to toxins.     

邻苯二甲酸二异壬酯致小鼠肝组织氧化损伤的研究

研究邻苯二甲酸二异壬酯对小鼠肝细胞的氧化损伤.以昆明小鼠为受试动物,随机分为5组,包括1个阴性对照组、4个邻苯二甲酸二异壬酯染毒组,染毒组按0.5,5,50,500mg/kg4个剂量水平,灌胃染毒小鼠14d.以肝组织匀浆测定活性氧(ROS)、还原型谷胱甘肽(GSH)、丙二醛(MDA)和8-羟基脱氧鸟苷(8-OHdG)的含量;以肝组织细胞测定DNA-蛋白质交联(DPC)系数.随着邻苯二甲酸二异壬酯染毒剂量的升高,肝组织的ROS、MDA、8-OHdG含量和DPC系数逐渐上升,GSH含量逐渐降低,各指标呈一定的剂量-效应关系.染毒剂量为50mg/kg时, ROS、GSH、8-OHdG含量和DPC系数差异有统计学意义(P< 0.05, P< 0.01);染毒剂量为500mg/kg时,上述指标差异均有统计学(P< 0.05, P< 0.01).同时对小鼠肝组织形态进行光镜观察,结果表明,随着染毒剂量的加大,小鼠肝细胞的病理损伤越严重.较高剂量(350mg/kg)的邻苯二甲酸二异壬酯能造成小鼠肝组织的氧化损伤.