Antioxidant role of propolis extract against oxidative damage of testicular tissue induced by insecticide chlorpyrifos in rats

Pesticides induce oxidative stress leading to generate free radicals and alternate the antioxidant or oxygen free radical scavenging enzyme system. This study was conducted to investigate the oral toxicity of chlorpyrifos toward male rat and the oxidative stress of the sub-lethal dose (9 mg/kg; 1/25 LD₅₀) on the lipid peroxidation level (LPO), reduced glutathione content (GSH) and antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities of testicular tissue. Also, the protective effects of propolis extract (50 mg/kg b.w.) alone or in combination with chlorpyrifos were investigated. The oral administration of chlorpyrifos significantly caused elevation in LPO level by 1.79-fold as compared to control. The activities of antioxidant enzymes including CAT, SOD, GPx and GST were decreased significantly (23.66%, 27.75%, 29.13% and 11.52%) as well as the level of GSH decreased by 21.97% in testicular tissue as compared to control animals. Co-administration of propolis extract with chlorpyrifos or alone in male rats decreased LPO level, normalized CAT, SOD GPx and GST activities, while GSH content was increased in testicular tissue. We conclude that propolis extract significantly reduces chlorpyrifos-induced oxidative stress in rat testis and the protective effect of the pre-treatment with propolis extract as attenuating agent could be due to its antioxidant properties.     

Hydrogen peroxide pretreatment alters the activity of antioxidant enzymes and protects chloroplast ultrastructure in heat-stressed cucumber leaves

To elucidate the physiological mechanism of heat stress mitigated by exogenous hydrogen peroxide (H₂O₂) further, seedlings of Cucumis sativus cv Lvfeng no. 6 were subjected to two temperatures (42/38 and 25/18 °C) after pretreatment with 1.5 mM H₂O₂. We investigated whether exogenous H₂O₂ could protect chloroplast ultrastructure under heat stress (42/38 °C) and whether the protective effect was associated with the regulation of antioxidant enzymes. The heat condition disintegrated the membranes of 71.4% chloroplasts in the leaf cells and resulted in the elevated levels of malondialdehyde (MDA) and endogenous H₂O₂. When H₂O₂ pretreatment was combined with the heat stress, the abnormal chloroplasts occurred at a rate of 33.3%, and the contents of MDA and endogenous H₂O₂ were decreased. Heat stress and exogenous H₂O₂ both increased the activities of antioxidant enzymes such as glutathione peroxidase (GSH-Px, EC 1.11.1.9), dehydroascorbate reductase (DHAR, EC 1.8.5.1), monodehydroascorbate reducatase (MDHAR, EC 1.6.5.4), and glutathione reductase (GR, EC 1.6.4.2). The combined effect of heat stress and H₂O₂ pretreatment led to higher activity of antioxidant enzymes including superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), GSH-Px, DHAR, MDHAR and GR in comparison to the heat treatment alone. We propose that exogenous H₂O₂ increases antioxidant enzyme activities in cucumber leaves, decreases lipid peroxidation, and thus protects the ultrastructure of chloroplasts under heat stress.     

Synthesis of strigolactones,a strategic account

Strigolactones (SLs) constitute a new class of plant hormones that have received growing interest in recent years. They firstly became known as signalling molecules for host recognition by parasitic plants, and for symbiosis of plants with arbuscular mycorrhizal fungi. Furthermore, they are involved in numerous physiological processes in plants, such as the regulation of plant architecture and the response to abiotic factors. SLs are produced by plants in extremely low quantities, and they may be unstable during the purification process. Therefore, their total synthesis is highly relevant for confirming the structures assigned on the basis of spectroscopic and other physical data. A second important theme in SL research is the design and synthesis of SL analogues that have a simplified structure while still featuring the essential bioproperties. This review summarises the strategy and synthesis of naturally occurring SLs, and the design and synthesis of SL analogues with appreciable bioactivity. © 2015 Society of Chemical Industry     

木薯外植体表面灭菌与增殖培养的研究

[目的]筛选出适合木薯组织培养的灭菌体系,为加快木薯组织快繁提供科学依据。[方法]以木薯品种GR891的腋芽为外植体,研究经甲基托布津杀菌剂处理和无处理外植体分别采用不同组合、不同处理时间对其表面灭菌的效果,同时研究6-BA和6-BA与NAA组合对丛芽诱导培养效果的影响。[结果]经甲基托布津杀菌剂处理后用体积分数75%乙醇消毒10 s＋质量分数0.1%升汞处理8 min效果最好,外植体存活率为61.3%;以MS＋6-BA 1.5 mg/L＋糖30 g/L＋琼脂6.5 g/L培养基诱导培养芽效果最好,有的丛芽能达到7～9株,丛芽生长速度快,健壮。[结论]建立了木薯GR891组织培养外植体灭菌与增殖培养体系。     

Stimulation of ROS-scavenging systems in squash (Cucurbita pepo L.) plants by compost supplementation under normal and low temperature conditions

The beneficial effect of compost, the final product of aerobic biodegradation of organic matter, on growth, lipid peroxidation [as malondialdehyde (MDA], hydrogen peroxide (H₂O₂) and superoxide anion (O₂^•−), activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), as well as reduced ascorbate (ASC) and glutathione (GSH) and their oxidized forms was investigated in squash (Cucurbita pepo L. cv. Eskandarany) plants exposed to normal and low temperature (LT) conditions. LT stress of 8 °C significantly reduced the plant growth of untreated plants, but compost alleviated the adverse effect of stress and significantly increased the fresh and dry weights under normal and stress conditions. LT also induced accumulation of H₂O₂ and O₂^•− and resulted in increased lipid peroxidation, pointing out to cellular oxidative stress. Under compost application, such reactive oxygen species (ROS) and peroxidized lipids were markedly reduced, but SOD, CAT, APX and GR activities, key enzymes of ROS-scavenging systems, were significantly increased. Data also indicated that there were general reductions in total ascorbate and glutathione pool in LT control plants, but compost-treated ones considerably have maintained higher levels of such redox metabolites. Significantly higher ratios of ASC/DHA (dehydroascorbate) and GSH/GSSG (glutathione disulfide) were generally found in compost-treated plants than in untreated-ones. It is evident that compost induced enhancement of LT tolerance was related to up-regulation of enzymatic and non-enzymatic antioxidant systems. Such enhancement would eventually protect plant cells from LT-induced oxidative stress reactions via scavenging ROS.     

氧乐果和吡虫啉对小麦过氧化物酶、谷胱甘肽还原酶及过氧化氢酶活性的影响

为明确常用杀虫剂对小麦抗氧化性的影响,研究了小麦幼苗期用不同浓度氧乐果和吡虫啉的营养液处理后144 h内对其过氧化物酶(POD)、谷胱甘肽还原酶(GR)及过氧化氢酶(CAT)活性的影响。结果表明:用400、800和1 600 mg/L的氧乐果处理小麦幼苗后24 h,POD活性均显著降低;1 600 mg/L的氧乐果处理后6 h,其CAT活性比对照降低了32.9%;各浓度氧乐果处理后144 h,GR活性均显著降低。而用25、50和100 mg/L的吡虫啉处理小麦幼苗后144 h内,只有50 mg/L处理组在12 h时的POD活性比对照升高了65.0%。杀虫剂对小麦幼苗中3种抗氧化酶活性的影响不仅与药剂种类有关,还具有一定的剂量效应与时间效应。     

Effect of Pichia membranaefaciens on ROS metabolism and postharvest disease control in citrus fruit

The yeast Pichia membranaefaciens has antagonistic effects against a wide range of phytopathogenic fungi that cause postharvest fruit decay. This work evaluated the effects of P. membranaefaciens on the reactive oxygen species (ROS) metabolism and disease control in harvested citrus fruit (Citrus sinensis L. Osbeck). The lesion diameter caused by Penicillium italicum and Penicillium digitatum on citrus fruit was remarkably reduced when the fruit was point-inoculated or dipped in a suspension of P. membranaefaciens at 1 × 10⁸ CFU mL⁻¹. The application of P. membranaefaciens on citrus fruit enhanced the activity of superoxide dismutase, ascorbate peroxidase, and glutathione reductase, as well as the levels of hydrogen peroxide, the superoxide anion and glutathione, but inhibited the decreasing ascorbic acid content. Furthermore, catalase activity was decreased by the same treatment. These results indicated that yeast treatment induced the synthesis of antioxidant enzymes which might have antagonistic effects against postharvest green and blue mold infection in citrus fruit.