Preventive effects of Cassia auriculata L. flowers on brain lipid peroxidation in rats treated with streptozotocin

The effect of aqueous extract of the flowers of Cassia auriculata were examined on antioxidants and lipid peroxidation in the brain of streptozotocin diabetic rats. Significant increase in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and reduced glutathione were observed in brain on treatment with Cassia auriculata flower extract (CFEt) and glibenclamide. Both the treated groups showed significant decrease in thiobarbituric reactive substances (TBARS) and hydroperoxide formation in brain, suggesting its role in protection against lipid peroxidation induced membrane damage. Since the study of induction of the antioxidant enzymes is considered to be a reliable marker for evaluating the antiperoxidative efficacy of medicinal plant, these findings are suggestions of possible antiperoxidative role played by Cassia auriculata flower extract.     

Comparative effects of selenite and selenite on the glutathione-related enzymes activity in pig blood platelets

The effects of inorganic selenium (Se) compounds (sodium selenite and selenate) on the activities of glutathione-related enzymes (glutathione peroxidase, glutathione-S-transferase [GST] and glutathione reductase [GR]) in pig blood platelets were investigated in vitro. GST activity in blood platelets treated with 10⁻⁴ M of selenite was reduced to 50%, whereas no decrease GST activity was observed after the treatment of platelets with the same dose of selenate. In platelets incubated with physiological doses (10⁻⁷, and 10⁻⁶ M) of Se compounds, the activity of glutathione peroxidase (GSH-Px) was enhanced (about 20%). GR activity after the exposure of platelets to tested Se compounds was unaffected.     

Effects of L-Carnitine on the Formation of Fatty Acid Ethyl Esters in Brain and Peripheral Organs after Short-Term Ethanol Administration in Rat

A study was undertaken in rats to evaluate the effects of short-term oral ethanol administration on the levels of fatty acid ethyl esters (FAEE) in brain and peripheral organs in the presence and absence of pretreatment with L-carnitine. Administration of ethanol to rats for seven days resulted in fatty acid ethyl ester formation, particularly in the heart and brain, but also in the kidney and liver. FAEE generation was associated with a significant increase of GSH transferase activity. Treatment with L-carnitine significantly reduced both FAEE and GSH transferase activity, and these effects were associated with a significant decrease in alcohol blood concentrations. The present evidence supports the hypothesis that fatty acid ethyl esters could be mediators involved in the production of alcohol-dependent syndromes. Administration of L-carnitine through an increment in lipid metabolism and turnover, and by the modulation of cellular antioxidant enzymes, greatly reduces these metabolic abnormalities supporting its potential usefulness as a pharmacological tool in alcoholism management.I wish to dedicate this paper to the memory of Prof. Victor Rizza who tragically disappeared on the 2nd of September when this paper was in press     

八角茴香提取物对长角扁谷盗成虫的熏蒸作用及其酶活性的影响

为探索八角茴香的杀虫活性及其作用机理,采用密闭容器熏蒸法测定八角茴香干果的甲醇、乙酸乙酯、石油醚3种溶剂提取物对长角扁谷盗成虫的杀虫活性,及其对试虫体内乙酰胆碱酯酶(AChE)和谷胱甘肽-S-转移酶(GSTs)活性的影响。结果表明:3种提取物对试虫均有较强的熏杀活性,熏杀效果随着处理剂量的提高和处理时间的延长而增强,熏蒸72 h后,20.0 mg/L甲醇、乙酸乙酯、石油醚提取物对试虫的校正死亡率分别为89.93%、96.71%和91.56%,LD50分别为7.16、4.57、5.42 mg/L,以乙酸乙酯提取物的熏杀效果最好。3种提取物对试虫体内的AChE、GSTs活性均表现出明显的剂量效应和较强的时间效应,随着处理剂量的升高,对2种酶活力多数表现为抑制作用增强,而低剂量(1.25 mg/L)的甲醇提取物对AChE具有一定的诱导作用;乙酸乙酯、石油醚提取物在48 h而甲醇提取物在60 h对AChE、GSTs活性抑制作用最强;3种溶剂提取物对AChE、GSTs活性的抑制作用大小均表现为乙酸乙酯>石油醚>甲醇。提取物对酶活性的抑制作用与熏杀效果整体呈正相关,说明AChE、GSTs活性下降可能是造成试虫死亡的重要原因之一。因此,八角茴香具有潜在的杀虫应用研究价值。     

Preliminary studies on the involvement of glutathione metabolism and redox status against zinc toxicity in radish seedlings by 28-Homobrassinolide

The effect of exogenous application of 28-Homobrassinolide (HBR) on radish (Raphanus sativus L.) seedlings under zinc (Zn²⁺) stress on glutathione (GSH) production, consumption and changes in redox status was investigated. Zinc toxicity resulted in oxidative burst as evidenced by increased accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) content. These stress indices were significantly decreased by HBR supplementation. Under Zn²⁺ stress, GSH pool was decreased, while the contribution of oxidized glutathione (GSSG) to total GSH increased (GSSH/GSH ratio), this translated into significant reduction of GSH redox homeostasis. In addition, an increase of phytochelatins (PCs) was observed. In radish seedlings under Zn²⁺ stress, the activities of gamma-glutamylcysteine synthetase (γ-ECS), glutathione synthetase (GS), glutathione peroxidase (GPX), glutathione-S-transferase (GST) and cysteine (Cys) levels increased but the activity of glutathione reductase (GR) decreased. However, application of HBR increased the GSH pool and maintained their redox ratio by increasing the enzyme activities of GSH biosynthesis (γ-ECS and GS) and GSH metabolism (GR, GPX and GST). The results of present study are novel in being the first to demonstrate that exogenous application of HBR modulates the GSH synthesis, metabolism and redox homeostasis to confer resistance against Zn²⁺ induced oxidative stress.     

OsRPK1, a novel leucine-rich repeat receptor-like kinase,negatively regulates polar auxin transport and root development in rice

Background

Leucine-rich-repeat receptor-like kinases (LRR-RLKs) represent the largest subfamily of putative RLKs in plants. Although several members in this subfamily have been identified, the studies about the relationships between LRR-RLKs and root development are still few. We previously identified a novel LRR-RLK in rice roots, and named it OsRPK1.

Methods

In this study, we first detected OsRPK1 kinase activity in vitro, and assessed its expression profile. We then investigated its biological function using transgenic rice plants over- and under-expressing OsRPK1.

Results

The OsRPK1 gene, which encodes a Ca^2 +-independent Ser/Thr kinase, was predominantly expressed in root tips, leaf blades, and undifferentiated suspension cells, and was markedly induced by treatment with auxin or ABA. Knockdown of OsRPK1 promoted the growth of transgenic rice plants, and increased plant height and tiller numbers. In contrast, over-expressing plants showed undeveloped adventitious roots, lateral roots, and a reduced root apical meristem. OsRPK1 over-expression also inhibited the expression of most auxin efflux carrier OsPIN genes, which was accompanied by changes in PAT and endogenous free IAA distribution in the leaves and roots.

Conclusions

The data indicated that OsRPK1, a novel leucine-rich-repeat receptor-like kinase, affects the root system architecture by negatively regulating polar auxin transport in rice.

General significance

This study demonstrated a common regulatory pathway of root system development in higher plants, which might be initiated by external stimuli via upstream receptor-like kinases and downstream carriers for polar auxin transport.     

日本血吸虫GST蛋白和14-3-3蛋白的研究进展

血吸虫病是严重危害人类健康的人兽共患病之一,在全球范围内,血吸虫病曾在76个国家和地区流行,有超过2亿人感染了血吸虫病。目前,世界上采取了一些人畜同步治疗等综合防治措施,虽取得了一定的成效,但仍面临着成本高、再感染率高等一系列问题。因此,寻找新的治疗药物、疫苗候选分子以及开发高度特异且敏感的标准化免疫诊断试剂是当前日本血吸虫病基础研究的重要内容。主要对WHO提出的最具潜力的疫苗候选分子血吸虫GST蛋白以及参与血吸虫许多生物学功能的14-3-3蛋白的最新研究进展进行一些阐述。     

一个致倦库蚊杀虫剂敏感品系的筛选

化学防治是控制蚊虫传播疾病的主要方法, 抗性监测表明我国蚊虫已对有机磷、 有机氯、 氨基甲酸酯和拟除虫菊酯类杀虫剂产生了不同程度的抗性。蚊虫抗药性的分子机制主要包括靶标抗性和三大解毒酶家族带来的代谢抗性。筛选对杀虫剂敏感的品系是抗性监测和抗性机理研究必不可少的材料。本研究通过从一个致倦库蚊Culex pipiens quinquefasciatus野生种群筛选无乙酰胆碱酯酶G119S突变且具有低活性羧酸酯酶、 P450单加氧酶和谷胱甘肽-S-转移酶的单雌系, 建立了一个对杀虫剂敏感的致倦库蚊品系。该品系的羧酸酯酶活性是敏感品系S-lab的2.5倍, P450单加氧酶和谷胱甘肽-S-转移酶的活性与S-lab相当。生物测定表明, 与S-lab相比, 该品系对有机磷杀虫剂有低于2倍的抗性, 对氨基甲酸酯和拟除虫菊酯类杀虫剂没有抗性, 可以作为相对敏感品系用于抗性监测。     

土壤低剂量芘污染对蚯蚓若干生化指标的影响

通过人工污染土壤的方法,设计芘的暴露浓度为0、60、120、240、480、960μg.kg-1.暴露实验进行1、3、7和14d后,分别检测蚯蚓内脏中细胞色素P450含量、谷胱甘肽转移酶(GST)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量.结果表明,在供试浓度范围内,蚯蚓内脏中各生化指标对污染物暴露指示的敏感性存在差异:其中P450含量、GST和SOD活性最为敏感;POD和CAT活性次之;而MDA含量未对低剂量的芘暴露起到明显的指示作用.研究同时发现,低剂量污染物暴露的时间效应要强于剂量效应的影响.因而,在进行生态毒性诊断时,采用多指标和多时段的检测对增强指示的灵敏性和有效性尤为重要.     

Ohr, an in vivo-induced gene in Actinobacillus pleuropneumoniae, is located on a genomic island and requires glutathione-S-transferase for activity

Actinobacillus pleuropneumoniae is the causative agent of severe necrotizing pneumonia in swine. Previously, we identified the ohr gene encoding organic hydroperoxide reductase as specifically induced during infection of pigs, induced in vitro by organic peroxides but not other oxygen radicals, and present in A. pleuropneumoniae serotypes 1, 9 and 11 but not in other serotypes ( Shea & Mulks, 2002 ). Through analysis of flanking genomic sequence, we identify a homologue of gst , which encodes glutathione- S -transferase, immediately downstream of ohr and demonstrate that ohr-gst confers low but uninducible Ohr activity to serotype 5. We further identify a genomic island of 9.3 kb, flanked by lysR and araC homologues, in serotypes 1, 9 and 11, which contains ohr and gst . In serotypes 2–8, 10 and 12, this region of the genome contains a 1.1-kb islet with a putative transposase flanked by lysR and araC .