Goldfish exposure to cobalt enhances hemoglobin level and triggers tissue-specific elevation of antioxidant defenses in gills, heart and spleen

Cobalt ions can enhance the generation of reactive oxygen species (ROS), which may be the reason for cobalt toxicity. This study aimed to determine whether Co(2+) toxicity in goldfish is related to induced oxidative stress in gills, heart and spleen, and to assess responses of antioxidant systems. Exposure of goldfish to 50, 100 and 150 mg L(-1) of Co(2+) for 96 h elevated total hemoglobin in blood by 23, 44 and 78%, respectively. In gills, cobalt exposure enhanced lipid peroxide levels and activities of primary antioxidant enzymes; superoxide dismutase (SOD) rose by 125% and glutathione peroxidase (GPx) increased by 53-296%. Glutathione-S-transferase (GST) activity also increased by 117-157% and glucose-6-phosphate dehydrogenase (G6PDH) enhanced by 46-96%. Heart showed limited effects of fish exposure to 50 or 100 mg L(-1) of Co(2+), but the exposure to 150 mg L(-1) of Co(2+) elevated concentrations of lipid peroxides by 123% and activities of GPx by 98% and SOD by 208%. The most substantial effects of goldfish exposure to Co(2+) were observed in spleen: a decrease in total protein concentration by 44-60% and high molecular mass thiols by 59-82%, reduced activities of catalase by 24-58% and GR by 25-68%, whereas the level of low molecular mass thiols increased by 153-279% and activities of GPx, GST, G6PDH were enhanced by 114-120%, 192-769%, and 256-581%, respectively. The data show that fish exposure to 50-150 mg L(-1) of Co(2+) elevates blood hemoglobin level, mimicking effects of hypoxia, and causes the activation of defense systems against ROS.     

大豆胰蛋白酶抑制剂和防御信号物质对斜纹夜蛾解毒酶的影响

在昆虫与植物漫长的相互作用中,植物合成多种抗虫物质并采用防御信号转导系统抵御昆虫,昆虫也具有多种解毒酶系统保护其免受植物毒素的毒害.本文研究了人工添加大豆胰蛋白酶抑制剂和植物防御信号物质对斜纹夜蛾幼虫羧酸酯酶和谷胱甘肽-S-转移酶活性的影响.结果表明:持续6代自幼虫2龄或3龄开始喂养含有大豆胰蛋白酶抑制剂的人工饲料,其5龄幼虫中肠和脂肪体内羧酸酯酶、谷胱甘肽-S-转移酶活性显著升高,2、3龄处理的继代幼虫中肠和脂肪体内羧酸酯酶活性均在第二代达到最大值,分别为对照的2.06、2.40倍和1.96、2.70倍;其谷胱甘肽-S-转移酶活性则分别于第4、2代达到最大值,分别为对照的7.03、11.58倍和5.71、3.60倍,并呈现先升高再降低的趋势.预先接触外源信号物质茉莉酸甲酯、水杨酸甲酯48 h和添加大豆胰蛋白酶抑制剂均可使斜纹夜蛾幼虫中肠、脂肪体内羧酸酯酶和谷胱甘肽-S-转移酶的活性显著升高,且预先接触茉莉酸甲酯和水杨酸甲酯48 h可减缓大豆胰蛋白酶抑制剂对幼虫中肠和脂肪体内羧酸酯酶、谷胱甘肽-S-转移酶活性的作用效果.     

大豆胰蛋白酶抑制剂和防御信号物质对斜纹夜蛾解毒酶的影响

在昆虫与植物漫长的相互作用中,植物合成多种抗虫物质并采用防御信号转导系统抵御昆虫,昆虫也具有多种解毒酶系统保护其免受植物毒素的毒害.本文研究了人工添加大豆胰蛋白酶抑制剂和植物防御信号物质对斜纹夜蛾幼虫羧酸酯酶和谷胱甘肽-S-转移酶活性的影响.结果表明： 持续6代自幼虫2龄或3龄开始喂养含有大豆胰蛋白酶抑制剂的人工饲料,其5龄幼虫中肠和脂肪体内羧酸酯酶、谷胱甘肽-S-转移酶活性显著升高,2、3龄处理的继代幼虫中肠和脂肪体内羧酸酯酶活性均在第二代达到最大值,分别为对照的2.06、2.40倍和1.96、2.70倍;其谷胱甘肽-S-转移酶活性则分别于第4、2代达到最大值,分别为对照的7.03、11.58倍和5.71、3.60倍,并呈现先升高再降低的趋势.预先接触外源信号物质茉莉酸甲酯、水杨酸甲酯48 h和添加大豆胰蛋白酶抑制剂均可使斜纹夜蛾幼虫中肠、脂肪体内羧酸酯酶和谷胱甘肽-S-转移酶的活性显著升高,且预先接触茉莉酸甲酯和水杨酸甲酯48 h可减缓大豆胰蛋白酶抑制剂对幼虫中肠和脂肪体内羧酸酯酶、谷胱甘肽-S-转移酶活性的作用效果.     

Identification and classification of detoxification enzymes from Culex quinquefasciatus (Diptera: Culicidae)

Molecular characterization of the insecticide resistance has become a hot research topic ever since the first disease transmitting arthropod (Anopheles gambiae) genome sequence has unveiled in 2002. A recent publication of the Culex quinquefasciatus genome sequence has opened up new opportunities for molecular and comparative genomic analysis of multiple mosquito genomes to characterize the insecticide resistance. Here, we utilized a whole genome sequence of Cx. quinquefasciatus to identify putatively active members of the detoxification supergene families, namely cytochrome P450s (P450s), glutathione-S-transferases (GSTs), and choline/carboxylesterases (CCEs). The Culex genome analysis revealed 166 P450s, 40 GSTs, and 62 CCEs. Further, the comparative genomic analysis shows that these numbers are considerably higher than the other dipteran mosquitoes. These observed speciesspecific expansions of the detoxification super gene family members endorse the popular understanding of the involvement of these gene families in protecting the organism against multitudinous classes of toxic substances during its complex (aquatic and terrestrial) life cycle. Thus, the generated data set may provide an initial point to start with to characterize the insecticide resistance at a molecular level which could then lead the development of an easy to use molecular marker to monitor the incipient insecticide resistance in field environs.     

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.     

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。     

Chemoresistance and chemosensitization in cholangiocarcinoma

One of the main difficulties in the management of patients with advanced cholangiocarcinoma (CCA) is their poor response to available chemotherapy. This is the result of powerful mechanisms of chemoresistance (MOC) of quite diverse nature that usually act synergistically. The problem is often worsened by altered MOC gene expression in response to pharmacological treatment. Since CCA includes a heterogeneous group of cancers their genetic signature coding for MOC genes is also diverse; however, several shared traits have been defined. Some of these characteristics are shared with other types of liver cancer, namely hepatocellular carcinoma and hepatoblastoma. An important goal in modern oncologic pharmacology is to develop novel strategies to overcome CCA chemoresistance either by increasing drug specificity, such as in targeted therapies aimed to inhibit receptors with tyrosine kinase activity, or to increase the amounts of active agents inside CCA cells by enhancing drug uptake or reducing efflux through export pumps. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.     

Gender-related differences in susceptibility to oxidative stress in healthy middle-aged Serbian adults

Gender-related differences in the association between polymorphism of xenobiotic-metabolising enzymes or non-genetic biomarkers and susceptibility to oxidative stress was assessed in healthy middle-aged Serbian adults, by urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG/creatinine) and total antioxidant status in serum (TAOS). Females were more susceptible to oxidative stress. In both genders, positive predictor of the antioxidative protection was serum triglyceride, while BMI?<25?kg/m² was associated with oxidative stress. Susceptibility to oxidative stress in males was associated with GSTT1*null allele and increased serum iron, but in females, it was decreased serum bilirubin. Early identification of the risk factors could be important in the prevention of oxidative stress-related diseases.     

Metals and seeds: Biochemical and molecular implications and their significance for seed germination

Seeds contain the embryo as a new plant in miniature and have two major functions, reproduction and dispersal. Seed formation completes the process of plant reproduction and, with seed germination, the next plant generation starts. Given the ever-increasing environmental pollution with metal(loid)s, it is perhaps surprising that relatively few reports detail the impacts of metals on seed metabolism, viability and germination in comparison to the numerous publications on the effects of metals in vegetative tissues, particularly roots and shoots. This review provides information on metal(loid) homeostasis, detoxification and tolerance in relation to seed metabolism and performance. The delivery of metals from the mother plant into seeds and their implications on seed development are discussed, as are their uptake upon seed imbibition and subsequent effects on seed germination. Implications for seeds and seedlings on the biochemical and molecular level are discussed and finally, applied aspects are considered regarding the use of seeds for soil and water purification, and in phytoremediation programmes. We conclude with a perspective on future metal research in relation to seed biology.     

Purification and properties of a glutathione-S-transferase from corn which conjugates s-triazine herbicides

A glutathione-S-transferase involved in atrazine conjugation was purified 43-fold from corn with a total yield of 36%. The purified enzyme has a MW of 45 000 as determined by gel filtration. The estimated activation energy of the enzyme is 6.4 kcal/mol and the optimum pH for activity between 8 and 8.5. Substrate specificity studies with s-triazines indicated that atrazine was the best substrate followed by simazine and propazine. The Cl group at the 2-position was essential for enzyme activity, and replacement by a SCH₃ group resulted in a total loss of activity. The absence of an alkyl group resulted in a reduction of conjugation and 2-chloro-4,6-bis-amino-s-triazine was the poorest substrate. With insecticidal substrates (organophosphates), conjugating activity was observed only with diazinon and little or no activity was observed with ethyl parathion, malathion and etrimfos. No activity was found using methyl iodide as a substrate. The purified enzyme has properties similar to those of an aryl-S-transferase. Quinones were inhibitors of this enzyme.