Phytotoxicity of Roundup Ultra 360 SL in aquatic ecosystems: Biochemical evaluation with duckweed (Lemna minor L.) as a model plant

Glyphosate-based herbicides (e.g. Roundup Ultra 360 SL) are extensively used in aquatic environment. Although glyphosate is more environmental favorable than many other herbicides, it may be exceptionally dangerous for aquatic ecosystems through high water solubility. Thus, the aim of the work was quantification of influence of Roundup Ultra 360 SL (containing isopropylamine salt of glyphosate as an active ingredient) on biomass and chlorophyll content within duckweed (Lemna minor L.). Moreover, changes in polyamine content and activity of such antioxidative enzymes as catalase (CAT) and ascorbate peroxidase (APX) were assayed in order to determine the biochemical mechanisms of L. minor response to the herbicide treatment. Obtained results showed that phytotoxicity of the herbicide was connected with decrease in chlorophyll-a, b and a+b content, and reduction of biomass growth. Roundup, similarly to some abiotic and biotic stressors, caused over-accumulation of putrescine, spermidine and total polyamines (PAs) within duckweed tissues. In addition an increase in CAT and APX activities suggested that stress generated by the herbicide treatment was at least partially connected with oxidative burst. Intensity of the duckweed responses to the herbicide was dependent on the applied herbicide level and/or duration of treatment.     

Selenium and vitamin E, natural antioxidants, protect rat cerebral cortex against dimethoate-induced neurotoxicity

Pesticides have been used in agriculture to enhance food production by eradicating unwanted insects and controlling disease vectors, nevertheless occupational exposure to high levels of these compounds can lead to neurodegenerative disorders, characterized by serious oxidative and neurotoxic effects. However, there is a lack of consensus as to which determinations are best used to quantify future risks arising from xenobiotic exposure and natural antioxidant interventions. Our study aims to determine the potential ability of selenium and/or vitamin E, used as nutritional supplements, to alleviate oxidative stress in cerebral cortex tissue induced by dimethoate, an organophosphorus pesticide. Adult Wistar rats were exposed either to dimethoate (0.2 g/L of drinking water), dimethoate + selenium (0.5 mg/kg of diet), dimethoate + vitamin E (100 mg/kg of diet), or dimethoate + selenium + vitamin E, for 30 days. Exposure to dimethoate increased malondialdehyde levels, protein carbonyl groups and advanced oxidation protein products, while Na⁺K⁺-ATPase, acetylcholinesterase and butyrylcholinesterase activities decreased in the cerebral cortex. An increase in glutathione peroxidase, superoxide dismutase and catalase activities and a decrease in glutathione, non-protein thiols and vitamin C levels were observed. Administration of selenium and/or vitamin E through the diet in dimethoate treated rats ameliorated the biochemical parameters cited above. The histological findings confirmed the biochemical results. The model of this study that we employed characterized the relationships between dimethoate-induced neurotoxicity and its alleviation by natural antioxidants like selenium and vitamin E. These elements may be considered beneficial for the protection of cerebral cortex against injury induced by dimethoate.     

小苍兰切花瓶插生理研究

 以小苍兰品种‘上农金皇后’为材料,观察其鲜切花瓶插过程中花的发育变化及生理特性。结果表明,小苍兰切花单花的瓶插寿命不足一周,整个花序可达10 d。花瓣中的含水量和可溶性蛋白含量在瓶插前期升高,后期则加速下降。超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）活性呈现相似的变化趋势,在瓶插前期均呈上升趋势,4 d达到峰值后稳步下降;过氧化物酶（POD）活性则在整个瓶插期间持续上升。超氧阴离子自由基（）随瓶插时间增加而不断积累。丙二醛（MDA）含量和相对电导率（EL）也随瓶插时间增加而上升。失水、抗氧化酶活性下降、自由基的累积以及膜脂过氧化水平的增加是小苍兰切花衰老的主要原因。     

Psammaplin A对牛老化卵母细胞体外发育的影响

为探讨组蛋白去乙酰化抑制剂Psammaplin A(PsA)对牛老化卵母细胞体外发育的影响,本试验将卵母细胞随机分为对照组、老化组和50mmol/L PsA处理的老化组(PsA组)。应用免疫荧光染色和JC-1检测牛卵母细胞孤雌激活后的囊胚率、囊胚中的细胞数、细胞凋亡、活性氧(reactive oxygen species,ROS)、谷胱甘肽(glutathione,GSH)和胚胎线粒体膜电位强度。结果显示,老化组囊胚率显著低于PsA组及对照组(P<0.05),PsA组囊胚率与对照组间无显著差异(P>0.05)。对照组及PsA组囊胚内细胞数显著高于老化组(P<0.05),PsA组囊胚内细胞数与对照组间无显著差异(P>0.05);老化组细胞凋亡率显著高于对照组及PsA组(P<0.05),PsA组细胞凋亡率显著高于对照组(P<0.05)。老化组MⅡ期卵母细胞的GSH水平显著低于对照组与PsA组(P<0.05),对照组与PsA组的GSH水平无显著差异(P>0.05)。老化组1细胞期胚胎ROS水平显著高于对照组和PsA组(P<0.05),PsA组ROS水平显著高于对照组(P<0.05)。老化组4-8细胞早期胚胎的线粒体膜电位强度显著低于对照组和PsA组(P<0.05),对照组线粒体膜电位强度显著高于PsA组(P<0.05)。综上所述,PsA可有效延缓牛卵母细胞的老化并提高卵母细胞和胚胎质量。     

The role of photoprotection in defence of two wheat genotypes against Zymoseptoria tritici

This study provides new insights into the role of photoprotection in preformed and induced defence of two wheat genotypes with contrasting phenotypes to infection by Zymoseptoria tritici. We investigated the mechanisms of the photoprotective response during early infection, including nonphotochemical quenching (NPQ), β-carotene-derived xanthophylls, reactive oxygen species, and the phytohormones abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA). Furthermore, we quantified the effects of pathogenesis on photosynthesis, stomatal control, and expression of plant defence molecular markers. The photoprotective mechanism of successful defence involved the qI component of NPQ leading to rapid down-regulation of photosystem II quantum yield and chlorophyll a:b, increased biosynthesis of the xanthophyll neoxanthin and ABA, and the expression of chloroplast-specific enzymes to engage in scavenging of O₂^●−. Elevated ABA in the resistant genotype correlated with preformed leaf defence traits including low stomatal density, increased expression of wax biosynthesis, and lignification. Z. tritici exhibited reduced germination and branching on the resistant host genotype and hijacked stomatal control in both genotypes by enhancing stomatal sensitivity to light. Increased biosynthesis of JA and anthocyanins, in contrast to SA, were quantified in the incompatible interaction. Our results indicate that ABA and JA in antagonistic action to SA were associated with defence in the resistant genotype, Cougar, against Z. tritici.     

MMP-9 and IL-1β as Targets for Diatoxanthin and Related Microalgal Pigments: Potential Chemopreventive and Photoprotective Agents

Photochemoprevention can be a valuable approach to counteract the damaging effects of environmental stressors (e.g., UV radiations) on the skin. Pigments are bioactive molecules, greatly attractive for biotechnological purposes, and with promising applications for human health. In this context, marine microalgae are a valuable alternative and eco-sustainable source of pigments that still need to be taken advantage of. In this study, a comparative in vitro photochemopreventive effects of twenty marine pigments on carcinogenic melanoma model cell B16F0 from UV-induced injury was setup. Pigment modulation of the intracellular reactive oxygen species (ROS) concentration and extracellular release of nitric oxide (NO) was investigated. At the cell signaling level, interleukin 1-β (IL-1β) and matrix metallopeptidase 9 protein (MMP-9) protein expression was examined. These processes are known to be involved in the signaling pathway, from UV stress to cancer induction. Diatoxanthin resulted the best performing pigment in lowering MMP-9 levels and was able to strongly lower IL-1β. This study highlights the pronounced bioactivity of the exclusively aquatic carotenoid diatoxanthin, among the others. It is suggested increasing research efforts on this molecule, emphasizing that a deeper integration of plant ecophysiological studies into a biotechnological context could improve the exploration and exploitation of bioactive natural products.     

马铃薯活体与离体叶片中ROS清除酶活性变化的比较

通过对抗马铃薯晚疫病品种紫花白和感病品种夏波蒂活体和离体两种状态下ROS清除酶系(SOD,POD,CAT)在0~4 d取样后酶活性的变化趋势比较,发现马铃薯不同品种的ROS清除酶活性的变化趋势均呈现出先降低后增加的态势,而且活体和离体条件下的变化趋势趋于一致。因此,我们认为可以利用马铃薯的离体叶片作为接种材料来间接的反映马铃薯植株活体叶片中的ROS清除酶系的活性变化。     

The Cd‐tolerant rice mutant cadH‐5 is a high Cd accumulator and shows enhanced antioxidant activity

To investigate the mechanism of cadmium (Cd) detoxification in rice (Oryza sativa L.), a Cd‐tolerant mutant cadH‐5, obtained by an Agrobacterium tumefaciens‐based gene‐delivery system, was used for a Cd‐tolerance and accumulation study. After 15 d of exposure to 0.75 mM CdCl₂, significant phenotypic differences were observed between the wild type (WT) and cadH‐5. When exposed to 0.5 mM CdCl₂, higher Cd levels were accumulated in cadH‐5 root cell wall, root cytosol, and membranes than those in WT. However, Cd concentrations in root tissues varied in both WT and cadH5. No significant difference of hydrogen peroxide (H₂O₂) concentrations was observed between WT and cadH‐5, while contents of cell‐wall polysaccharides and phytochelatins (PCs) in the mutant were higher compared to WT. The ratios of reduced glutathione to oxidized glutathione (GSH : GSSG) and ascorbate to dehydroascorbate (ASC : DHA) were lower in WT than in cadH‐5, while the NADPH : NADP⁺ ratio was different to the ratios of GSH : GSSG and ASC : DHA; the ascorbate peroxidase (APX, EC 1.11.1.11), glutathione peroxidase (GR, EC 1.6.4.2), dehydroascorbate reductase (DHAR, EC 1.8.5.1), and monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) activities were lower in WT compared to cadH‐5. Our results indicate that under long‐term Cd stress, cadH‐5 plants can accumulate more Cd with more PC. Also, the redox status of ASC‐GSH cycle was more inhibited in WT than in cadH‐5 plants, rendering WT less able to scavenge reactive oxygen species (ROS). The cadH‐5 mutant maintains relatively high ASC, GSH, and NADPH concentrations, ratios of ASC : DHA, GSH : GSSG, and NADPH : NADP⁺, as well as antioxidative enzymatic activities and PC concentrations. Thus, it is tolerant of relatively high Cd accumulation.