EXOGENOUS CALCIUM ALTERS ACTIVITIES OF ANTIOXIDANT ENZYMES IN TRIFOLIUM REPENS L. LEAVES UNDER PEG-INDUCED WATER DEFICIT

This study was designed to examine whether external calcium (Ca²⁺) would improve the tolerance of Trifolium repens L to polyethylene glycol (PEG)-induced water deficit, and to determine the physiological mechanisms of Ca²⁺ effect on plant tolerance to water deficit. T. repens seedlings were subjected to PEG-induced water deficit alone or combined with 5 mM calcium chloride (CaCl₂) for 72 h. During PEG-induced water deficit period, leaf relative water content (RWC) decreased gradually, and chlorophyll content increased after 24 and 48 h of water deficit but decreased below the control level after 72 h. The Ca²⁺-treated plants had higher RWC and chlorophyll content than untreated plants. Smaller amounts of thiobarbituric acid reactive substances (TBARS) and hydrogen peroxide (H₂O₂) accumulated in Ca²⁺-treated plants than in untreated plants during the period of water deficit. The activity of superoxide dismutase (SOD) increased gradually during the experimental period, and external Ca²⁺ treatment further promoted SOD activity under water deficit. The activity of the catalase (CAT) was not influenced after 24 and 48 h of water deficit and insignificantly increased after 72 h, whereas the activity of ascorbate peroxidase (APOX) increased linearly and glutathione reductase (GR) activity slightly increased over the course of treatment. Seedlings treated with Ca²⁺ had higher CAT, GR, and APOX activities than untreated plants under water deficit. These results suggested that exogenous Ca²⁺ application enhanced T. repens tolerance to PEG-induced water deficit, and this enhancement was related to alleviation of lipid peroxidation and maintenance of antioxidant activities.     

Induction of Glutathione and Glutathione S-transferase in Several Crops with the Treatment of Acetochlor

1　 Introduction　　 Glutathione S- transferases ( GST.EC2 .5 1 .1 8) are a large family of homo- dimeric or hetero- dimericenzyme.They can detoxify a large variety of xenobiotic compounds,including drugs,antibiotics,insecticidesand herbicides.The GST family is ubiquitous and a substantial amountof research is available characteringtheir role in many plants species.The tripeptide glutathione( GSH- 1 - glutamyl- 1 - cysteinyl- glycine) is themajor low- molecular- weight thiol constituent o…     

腐殖酸对克露增效作用的生理机制初探

为探讨腐殖酸增效防病的生理机制 ,测定了脯氨酸、丙二醛、谷胱甘肽含量、膜透性等生理指标。结果表明 ,腐殖酸复配克露降低了叶片脯氨酸、丙二醛含量、质膜透性及病情指数 ,而且促进了黄瓜的生长 ,提高了产量及谷胱甘肽含量。证明腐殖酸作为农药增效剂确实提高了黄瓜的抗病能力 ,起到对农药的增效作用     

Dynamics of phytate-zinc balance of fungi fermented cassava products (gari and flour)

Parsley is one of the medicinal herbs used by diabetics in Turkey. It has been reported to reduce blood glucose levels. In this study the effects of feeding parsley on diabetes-induced free radical mediated injury in rat aorta and heart tissues were investigated. Swiss albino rats were divided into six groups: Control, diabetic, parsley, diabetic + parsley, glibornurid, and diabetic + glibornurid. Rats were subjected to i.p. streptozotocin (STZ, 65 mg/kg) to induce diabetes. On the fourteenth day of the study, either parsley (2 g/kg) or glibornurid (5 mg/kg) were given for 28 days to the diabetic rats. Aorta and heart tissue lipid peroxidation and glutathione levels as well as blood glucose levels were determined. The results of the present study indicate that lipid peroxidation was increased and glutathione levels were decreased in both aorta and heart tissue of the diabetic rats. However, treatment of the diabetic rats with either parsley or glibornurid reversed the effects of diabetes on blood glucose, and tissue lipid peroxidation and glutathione levels.     

Effect of dietary selenium level on growth performance,body composition and hepatic glutathione peroxidase activities of largemouth bass Micropterus salmoide

An 8‐week growth trial was conducted to determine the effect of dietary selenium (Se) level on growth performance, body composition and hepatic glutathione peroxidase (GPx) activities of largemouth bass. Sodium selenite was added to the fish meal basal diet at 0, 0.2, 0.4, 0.6, 0.8 and 1.0 mg kg^?1 Se providing 0.97, 1.17, 1.42, 1.60, 1.85 and 2.06 mg Se kg^?1 diet respectively. Each diet was fed to triplicate groups of fish (initial mean body weight: 4.95 ± 0.03 g) in a closed indoor recirculating system. The Se concentration in the rearing water was not detectable during the whole experimental period. The highest weight gain was obtained in fish fed diets with 1.60 mg Se kg^?1, which was significant higher (P < 0.05) than the basal diet with 0.97 mg Se kg^?1 and did not differ significantly (P > 0.05) with the other treatments. Feed conversion ratio, protein efficiency ratio, protein productive value, apparent digestibility coefficients of dry matter and muscle composition were not significantly impacted (P > 0.05) by dietary treatments. Fish fed diets with ≥1.42 mg Se kg^?1 obtained higher liver lipid contents than treatments with lower dietary Se levels. Hepatic malondialdehyde (MDA) was unchanged (P > 0.05) in relation to dietary Se concentration. Hepatic GPx and glutathione reductase (GR) activities markedly increased and decreased (P < 0.05) with increasing dietary Se concentration, respectively, and both reached a plateau with ≥1.85 mg Se kg^?1. Based on growth performance, hepatic MDA and enzymatic responses of GPx and GR, the highest Se concentration (2.06 mg kg^?1) employed in our study was not harmful for largemouth bass, and the optimal dietary level should be 1.60–1.85 mg Se kg^?1 from sodium selenite, at a dietary vitamin E level of 400 IU kg^?1.     

草菇谷胱甘肽过氧化物酶编码基因vv-gpx01的序列特征及表达分析

依托草菇基因组及转录组数据,克隆得到1个谷胱甘肽过氧化物酶(GPx)编码基因,命名为vvgpx01。ZOOM软件的分析结果表明:该基因全长1 313 bp,含有4个外显子、3个内含子,编码228个氨基酸;5'端非翻译区长为12 bp,3'端非翻译区为452 bp;其中3个内含子在RNA加工过程中均存在保留现象。生物信息学分析结果表明:草菇的GPx01序列具备完整的谷胱甘肽过氧化物酶保守结构域;系统发育树显示,担子菌与子囊菌的GPx分别聚在了2个不同的分支上,草菇GPx01与双孢蘑菇亲缘关系较近并与其他伞菌目的真菌聚在1个分支上。另外,由内含子保留所产生的氨基酸序列均出现了不同程度的功能域缺失,这将导致谷胱甘肽过氧化物酶的失活。表达谱分析结果表明:vv-gpx01在整个草菇生长阶段都有表达,但表达量存在差异。推测,草菇GPx01可能通过可变剪接产生不同的转录本,通过调节不同转录本的表达水平来调控基因功能域的翻译水平及空间构型,最终实现酶活性的调节。     

硒的生化特性与谷胱甘肽系统

介绍了硒的生理生化特性,重点阐述了硒与谷胱甘肽系统在抗氧化防御体系中的作用以及硒蛋白的研究进展。硒和谷胱甘肽(GSH)系统在氧化防御反应中起着关键性作用。其中GSH的主要功能是直接阻断氧化物生成和促进抗氧化物生成的还原反应;此外,GSH在代谢、细胞信号传导和蛋白质间相互作用中也具有辅助性功能,还可调节机体防御反应。硒在哺乳动物细胞中的保护作用受含硒氨基酸如硒半胱氨酸、硒蛋氨酸的调控。谷胱甘肽过氧化物酶(GSH-Px)的活性位点含有硒半胱氨酸残基。其它含硒蛋白(如硒蛋白P和硫氧还蛋白还原酶)也具有抗氧化特性。合成的有机硒复合物(如Ebselen)在机体氧化应激中是一种极具应用前景的抗氧化剂。硒蛋白和有机硒复合物在预防过亚硝酸盐的生成中也起着重要作用。     

4种杀虫剂对番茄叶片GSH-ASA抗氧化系统的影响

为揭示杀虫剂对番茄叶片谷胱甘肽-抗坏血酸(GSH-ASA)氧化还原系统的影响,以粉番一号番茄为试验材料,采用田间试验方法,设定噻虫嗪、毒死蜱、苏云金杆菌、氯虫苯甲酰胺4种不同类型杀虫剂处理,以清水处理为对照,并针对处理后的番茄叶片组织内GR酶活性、GSH含量、ASA含量、GSH/GSSG、ASA/DHA在一段时间内的变化进行检测与分析。结果表明:4种杀虫剂处理后,番茄植株体内GSH-ASA抗氧化系统中的各物质含量及GR酶活性与对照植株之间均存在显著性差异,其中苏云金杆菌、毒死蜱和氯虫苯甲酰胺处理12h后植株组织内GR酶活性分别为0.185U/(g·min)、0.162U/(g·min)、0.162U/(g·min),而噻虫嗪处理在24h时植株组织内GR酶活性达最大值0.155U/(g·min)。尤其是在6~24h变化最显著,随着时间的延长,差异减小,在杀虫剂处理后168h基本恢复到对照水平,说明杀虫剂处理后,番茄植株体通过谷胱甘肽-抗坏血酸氧化还原系统对外源杀虫剂处理做出响应,但是植株对不同杀虫剂的响应有所不同,相对而言,在常用剂量的4种杀虫剂中,苏云金杆菌处理对番茄叶片抗氧化系统的影响作用最小。     

Effect of methyl parathion and chlorpyrifos on certain biomarkers in various tissues of guppy fish, Poecilia reticulata

Tests of acute toxicity were performed on the most common species of aquarium fish, Poecilia reticulata. Guppies (P. reticulata) were exposed to progressive concentrations of methyl parathion (MP) and chlorpyrifos (CPF); a semi-static method according to guidelines of OECD was used. Tests of acute toxicity were conducted using 10 fish for each separate concentration and for the control group. The results were subjected to probit analysis to determine the 96 h LC₅₀ values. The 96 h LC₅₀ values of MP and CPF to P. reticulata were 8.48 ppm/L (5.98–10.89) and 0.176 ppm/L (0.313–0.224) respectively. In addition, behavioral changes at each concentration were observed for the individual fish. Fish were exposed for 96 h to different sublethal concentrations of MP and CPF (¼ LC₅₀, 1/8 LC₅₀ and 1/10 LC₅₀) and their oxidative stress-induction potential was estimated in brain, liver and gills of fish. MDA content is induced in all tissues but maximum rise was observed in gills (161% and 153% for MP and CPF respectively). With regard to antioxidant defense system (ADS), GSH level decreased in the brain, liver and gills of tissues of MP treated fishes (22%, 6% and 13% respectively) and showed increase in brain and gills CPF treated (23% and 21% respectively). CAT, GST, GR and SOD levels fluctuated in all treatment groups relative to the control. Brain AChE showed dose-dependent inhibition in fish exposed to the higher concentrations reached 45% and 66% for MP and CPF respectively. Collective findings demonstrated that pesticide exposure of fish induced an increase in MDA and fluctuated ADS along with inhibited AChE. These findings may be used as valuable biomarkers for evaluation of water pollution.     

Clinico-Pathologic Findings in Young Pigs Fed Different Levels of Selenium,Vitamin E and Antioxidant

A randomized, blocked 2³ factorial experiment was conducted with 48 young pigs. The treatment factors were: 2 levels of selenium (55 and 115 µg/kg), 2 levels of vitamin E (3 and 53 mg/kg) and 2 levels of the antioxidant feed additive Ethoxyquin (0 and 150 mg/kg). All pigs were kept in single pens and fed ad libitum throughout the experimental period of 9 weeks, i.e. from 3 to 12 weeks of age.Plasma, heart, liver and muscle Se levels as well as whole blood glutathione peroxidase activity (EC 1.11.1.9 GSH-Px) were significantly higher in pigs given a dietary supplement of Se than in pigs given no supplement of Se (P ≤ 0.001). The Se-supplemented pigs showed a tendency to lower mean serum transaminase activity (ASAT and ALAT) than unsupplemented pigs, but the influence was significant (P ≤ 0.05) only for the ALAT activity.Blood vit. E levels were higher for pigs receiving a supplement of vit. E than for unsupplemented pigs (P ≤ 0.001), and so was the resistance of red blood cells against lipid peroxidation (ELP), as expressed by lower ELP values.There were no effects of Ethoxyquin supplementation on the biochemical variables included in the study.The histological examination of heart muscle showed that the score for changes was negatively influenced by both Se and vit. E supplement (P ≤ 0.001) and to some extent also by Ethoxyquin supplement (P ≤ 0.05). The histological picture of m. long dorsi was influenced only by the vit. E supplement (P ≤ 0.01). No histological changes were found in the liver in this study. There were inverse relationships between whole blood GSH-Px defluorescence time and blood Se, and between ELP and whole blood vit. E (P ≤ 0.001).