Impact of malathion stress on lipid metabolism in Limnonectus limnocharis

Despite mounting concerns about amphibian population declines, information on impact of pesticides on physiological changes is meager. The present study deals the influence of an organophosphate pesticide—malathion on the lipid metabolism of Limnonectus limnocharis under laboratory conditions. Changes in the lipid metabolism were analyzed in the liver, muscle, ovary, and testis of frogs exposed to lethal (10.67 mg L⁻¹ for 1, 2, 3, and 4 days) and sub-lethal (2.13 mg L⁻¹ for 1, 5, 10, 15, 20, and 25 days) concentrations of malathion. Upon lethal concentration treatment, against the increase of fatty acids, glycerol, and lipase activities in all tested tissues, there was decrease in the total lipids content over different durations. On the other hand, exposure to sub-lethal concentration, the amount of total lipids content, free fatty acids, glycerol and lipase activity increased. Changes in the lipid metabolism due to lethal concentration of malathion exposure could depict the negative impact on the reproductive success, which would result in decline of amphibian population.     

The effects of Saw palmetto on flumethrin-induced lipid peroxidation in rats

In the present study, 40 male Wistar albino rats were used and divided into 4 groups. The first group served as the control group; the second group was administered Saw palmetto extract at the dose of 20 mg/kg/bw; the third group was administered flumethrin at the dose of 15 mg/kg/bw; and the fourth group was administered a combination of 20 mg/kg/bw Saw palmetto extract and 15 mg/kg/bw flumethrin, for 21 days, orally. After the trial period, blood and tissue (liver, kidney and brain) samples were taken from the rats. Saw palmetto extract did not cause significant alterations in plasma and tissue malondialdehyde (MDA) levels, serum and tissue nitric oxide (NO) levels, erythrocyte and tissue superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities when compared to the controls (p > 0.05). Flumethrin led to increased plasma and tissue MDA levels, serum and tissue NO levels, tissue GSH-Px activities and decreased erythrocyte and tissue SOD and CAT activities, and erythrocyte GSH-Px activity, compared to the controls (p < 0.05). The flumethrin and Saw palmetto extract combination increased erythrocyte SOD activity and decreased brain GSH-Px activity as compared to flumethrin (p < 0.05). In conclusion, it was determined that Saw palmetto extract did not cause any negative effect on the prooxidant-antioxidant balance. While flumethrin stimulated lipid peroxidation; Saw palmetto extract at the dose of 20 mg/kg/bw did not exhibit enough antioxidant effect in rats.     

NbRbohB基因在本氏烟与疫霉菌互作中的功能分析

活性氧(active oxygen species, AOS)在植物抗病中发挥着重要作用,主要由NADPH氧化酶(nicotinamide adenine dinucleotide phosphate oxidase)系统产生.为明确NADPH氧化酶NbRbohB基因在本氏烟与疫霉菌亲和与非亲和性互作中的功能,采用荧光定量PCR技术以及病毒诱导的基因沉默方法探究了NbRbohB基因在本氏烟中对2种疫霉菌抗性中的作用,并利用NADPH氧化酶抑制剂对辣椒疫霉的抗性进行了检测.结果发现:2种疫霉菌均能诱导本氏烟发生氧迸发,且NbRbohB基因可能参与了疫霉菌诱导本氏烟发生的氧迸发过程.该基因沉默后降低了本氏烟对亲和互作辣椒疫霉菌的抗性,但对非亲和互作疫霉菌的抗性没有肉眼可见的影响;NADPH氧化酶抑制剂处理本氏烟后也能降低其对辣椒疫霉的抗性.表明该基因通过介导AOS产生,参与植物对亲和性与非亲和性互作疫霉的抗病反应,在亲和互作中尤为重要.     

In vivo chlorpyrifos induced oxidative stress: Attenuation by antioxidant vitamins

Chlorpyrifos (O,O′-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) exposure in rats causes elevation in the levels of thiobarbituric acid reactive substances (TBARS) and inhibition of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT), and glucose-6-phosphate dehydrogenase (G6PDH) activities in the liver, kidney, spleen, and brain of rats. The sublethal exposure of CPF also causes decrease in the levels of reduced glutathione (GSH) and consequent increase in oxidized glutathione (GSSG) levels, resulting in a significant decrease in GSH/GSSG ratio in all the rat tissues tested. These results clearly indicate that CPF exposure causes oxidative stress in rat tissues. However, CPF exposure to rats fed with antioxidant vitamins (vitamin A, E, and C) for 1 month, prevented derangement of these antioxidant parameters. The accumulation of TBARS was also not seen in tissues of rats fed with antioxidant vitamins on CPF exposure. AChE activity, which is sensitive to OP pesticides, was also not significantly inhibited in these rats on CPF exposure. The present findings clearly show that oral intake of a mixture of vitamin A, E, and C, protects the rats from CPF induced oxidative stress and suggesting that this treatment alleviates the toxicity of this pesticide.     

Evaluation of etoxazole toxicity in the liver of Oreochromis niloticus

The effects of etoxazole were evaluated in freshwater fish Oreochromis niloticus from five different sublethal etoxazole concentrations in order to study the biochemical response, photometrically. No changes were observed in the activities of antioxidant enzymes such as superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), and glutathione peroxidase (GPx, EC 1.11.1.9). These were measured in liver after 1, 7, and 15 days of exposure to sublethal concentrations of 0.2, 0.4, 0.6, 0.8, and 1% of field application rate (134.75 ppm). This study also investigated the levels of neurotoxic effects by the determination of acetylcholine esterase (AChE EC 3.1.1.7) and sodium-potassium adenosine 5^′-triphosphatase (Na⁺K⁺-ATPase, EC 3.6.3.9) activities. The exposure of fish led to sharp depletion in AChE activity while there is no significant alteration in Na⁺K⁺-ATPase activity. Up to 80% decreases were observed in the AChE activity. Since no difference was found in the activity of glutamate-pyruvate transaminase (GPT, EC 2.6.1.2), etoxazole did not show hepatotoxic effect. The results of the present study show that increase in the malondialdehyde (MDA) contents and decrease in the AChE activity can be used as biomarkers for monitoring toxicity in etoxazole exposure.     

Effect of tri-o-cresyl phosphate and methamidophos on Ca uptake by brain synaptosomes in hens

The effect of tri-o-cresyl phosphate (TOCP) and methamidophos (MET) on potassium-stimulated ⁴⁵Ca uptake by brain synaptosomes in hens was studied. An in vivo test showed that TOCP increased potassium-stimulated calcium uptake 2 h after its administration, but that verapamil suppressed the enhancement of this calcium uptake. An in vitro test showed that lower concentrations of TOCP stimulated calcium uptake by synaptosomes, but that higher concentrations inhibited the uptake. In contrast, all tested concentrations of MET obviously inhibited calcium uptake; however, since calcium uptake was decreased by the administration of verapamil plus either TOCP or MET, the mechanism by which TOCP affects the voltage-operated calcium channel may be different from that of MET. The disruption of calcium homeostasis may be involved in organophosphate-induced delayed neurotoxicity (OPIDN). Calcium channel blocker may ameliorate OPIDN by maintaining calcium homeostasis in nerve cells.     

Agrobacterium-mediated transformation efficiency is altered in a novel rice bacterial blight resistance cultivar and is influenced by environmental temperature

Y73 is a progeny of asymmetric somatic hybridization from an elite japonica rice cultivar (Dalixiang) and a wild rice (Oryza meyeriana), which shows high resistance to bacterial blight. It has a similar genetic background to its recurrent parent, Dalixiang, but Y73 has a high resistance to both bacterial blight and Agrobacterium. The transformation efficiency of Y73 was 35.7%, while Dalixiang had higher transformation efficiency (71.2%) under the same co-cultivation temperature (25 °C). These results indicate that the resistance to Agrobacterium tumefaciens in Y73 was linked with its characteristic of bacterial blight resistance, and was obtained from its donor parent, O. meyeriana. Further studies also showed that the resistance to A. tumefaciens was weakened at a lower temperature (20 °C). To study its molecular mechanism, the expression levels of genes associated with Agrobacterium-mediated transformation (OsMPKs, OsVIP1s and OsPR1s) in rice were investigated by Quantitative real-time PCR (qRT-PCR) analysis. The expression levels of OsMPK genes remained unchanged at different temperatures, while all OsVIP1s and almost all OsPR1s were up-regulated and transformation efficiency of Y73 was increased notably when infected by Agrobacterium at 20 °C compared with 25 °C. This study suggests that the bacterial blight resistance genes in Y73 also have an effect on Agrobacterium-mediated transformation and that the response to temperature is associated with the regulation of MAPK/VIP1 defense signaling pathway.     

Activation of paraquat in the earthworm Allolobophora chlorotica is mediated by NAD(P)H-cytochrome c reductase activities

This study reports that earthworms, Allolobophora chlorotica, are capable of biotransforming paraquat, a toxic herbicide, resulting in the formation of reactive oxygen species (ROS). We found that in earthworms the reduction of paraquat is mediated by NADPH- and NADH-cytochrome c reductase activities. The formation of superoxide anion (O₂⁻) from the incubation of paraquat with the earthworm extracts was demonstrated by using both Cypridina luciferin analog (CLA) chemiluminescence and the SOD-inhibitable cytochrome c reduction reaction. In addition, in vivo exposure of earthworms to paraquat in solution (24 and 48 h) was performed to investigate whether or not the herbicide affects the levels of the NAD(P)H-cytochrome c reductase activities. Although in vitro NADPH-cytochrome c reductase reduces paraquat more easily than the NADH-dependent activity, after the in vivo exposure an increase of NADH-cytochrome c reductase activity(s) by 12% compared to control values was observed, whereas NADPH-cytochrome c reductase activity was not affected. Xanthine oxidase (XO) is an enzyme implicated in paraquat toxicity, however, no XO was detected in earthworm extracts nor hypoxanthine was a source of electrons for the herbicide reduction. For comparative reasons menadione, a redox cycling quinone, was also incubated with the earthworm extracts. It was found that the incubation of menadione with earthworm extracts formed about two times more (O₂⁻) than with paraquat. It is concluded that the exposure of paraquat to earthworms could elicit radical formation and consequently toxic effects via oxidative stress-mediated mechanisms. The reduction of paraquat by the reductases leads to the formation of paraquat radical, which reacts with molecular oxygen, accounting for the formation of superoxide anion. Further studies are required to conclude that the observed increase of NADH-cytochrome c reductase activity(s) should be used as a biomarker for paraquat exposure in earthworms.     

Effects of N-acetylcysteine on oxidative responses in the liver of fenthion exposed Cyprinus carpio

The aim of this study was to evaluate the effects of different N-acetylcysteine doses on the tolerance to fenthion-induced oxidative stress, alterations in glutathione metabolism and cholinesterase specific activities in the liver by using freshwater fish Cyprinus carpio (Cyprinidae) as a model organism. An acute toxicity study was carried out to determine 96-h median lethal concentration of fenthion for this species (2.16 mg/L) and 80% of this concentration was applied in toxicity studies. Four groups, each containing eight fish were constituted as follows: Control group, fenthion treated group, 0.5 or 400 mg/kg NAC-injected + fenthion-treated groups. Biochemical analyses were carried out spectrophotometrically. Fenthion treatment significantly decreased total glutathione and glutathione levels, glutathione/glutathione disulfide ratio together with glutathione reductase and γ-glutamylcysteine synthetase specific enzyme activities. The higher dose of N-acetylcysteine increased the toxic effects of fenthion and γ-glutamyl transpeptidase specific activity while decreasing glutathione S-transferase specific activity. However, injection of the lower dose provided a limited protection against fenthion toxicity. In all exposure groups, lipid peroxidation increased and total protein levels decreased, while protein depletion was prevented by low dose of N-acetylcysteine application. Acetylcholinesterase and butyrylcholinesterase activities were at similar levels in the liver of C. carpio. A dose-dependent inhibition was observed in butyrylcholinesterase activity by N-acetylcysteine application. The results showed that fenthion had a significant oxidative stress inducing potential through the reduction of glutathione redox capacity. The critical point for overcoming oxidative stress by N-acetylcysteine in fenthion toxicity was the selection of the dose; N-acetylcysteine exerted its toxic effects by means of oxidative stress in fish liver at the higher dose.     

Protein metabolism in Spodoptera litura (F.) is influenced by the botanical insecticide azadirachtin

Azadirachtin, as a botanical insecticide, affects a wide variety of biological processes, including reduction of feeding, suspension of molting, death of larvae and pupae, and sterility of emerged adults in a dose-dependent manner. However, the mode of action of this toxin remains obscure. By using proteomic techniques, we analyzed changes in protein metabolism of Spodoptera litura (F.) induced by azadirachtin. Following feeding 4th instar larvae of Spodoptera litura (F.) with an artificial diet containing 1 ppm azadirachtin until pupation, 48 h old pupae were collected and protein samples prepared. Total soluble protein content was measured and the results showed that azadirachtin significantly influenced protein level. Moreover, the proteins were separated by 2-DE (two-dimensional polyacrylamide gel electrophoresis) and 10 proteins were significantly affected by azadirachtin treatment when compared to an untreated control. Six of these proteins were identified with peptide mass fingerprinting using MALDI-TOF-MS after in-gel trypsin digestion. These proteins are involved in various cellular functions. One identified protein may function as an ecdysone receptor, which regulates insect development, and reproduction. It is suggested that the botanical insecticide azadirachtin affects protein expression and the azadirachtin-related proteins would be essential for a better understanding of the mechanisms by which neem toxins exert their effects on insects.     

Glyphosate efficacy is contributed by its tissue concentration and sensitivity in velvetleaf (Abutilon theophrasti)

Glyphosate efficacy was examined in young velvetleaf plants from the standpoint of its tissue distribution and sensitivity. In whole plant assays, manual application of a sub-lethal dose to the first leaf resulted only in meristem injury while other tissues remained visually healthy. Our studies showed that this differential tissue response was caused by a combination of differential distribution as well as sensitivity to glyphosate. Using [¹⁴C]glyphosate, we measured tissue injury and glyphosate residue, and calculated tissue threshold for 50% growth inhibition. Our studies showed that roots and meristem have high glyphosate distribution (45 and 34% of translocated, respectively) and low inhibition thresholds (0.23 and 0.21 ppm, respectively) resulting in tissues that were easily killed by glyphosate. In contrast, the base stem contained a much higher inhibition threshold (8.4 ppm) with only intermediate distribution (10%) resulting in a tissue that was most difficult to kill. We observed a linear relationship between glyphosate dose and tissue concentration; furthermore, tissue distribution pattern was independent of dose or surfactants class. At a sub-lethal dose, sensitive tissues that received a large distribution of glyphosate were preferentially killed. As the dose was increased, more glyphosate was available for distribution, and all tissues received a proportionately greater amount of glyphosate. Plant death occurred when the applied dose was sufficient to attain the lethal threshold in all tissues.     

Water uptake and proline index as indicators of predisposition in tomato plants to Phytophthora nicotianae infection as influenced by abiotic stresses

To identify quantitative indicators of predisposition and stress development in tomato (Lycopersicon esculentum Mill. cv. Counter) plants infected by Phytophthora nicotianae Breda de Haan, we examined plants grown under stress-inducing nutrient conditions exposed to different levels of radiation and infection. The plant's response was investigated by analysing plant growth, proline content and disease development. From all plant growth parameters investigated, only leaf surface area and total fresh mass showed a response to radiation and infection, and both indicators were strongly correlated. However, because of the destructive character of these indicators, non- or minimal destructive indicators were sought. To this end, here we report that water uptake per plant (WP) and water uptake per plant and day (WPD) and proline content of leaves represent useful tools to assess plant health status during growth.     

Tolerance to acetolactate synthase and acetyl-coenzyme A carboxylase inhibiting herbicides in Vulpia bromoides is conferred by two co-existing resistance mechanisms

Vulpia bromoides is a grass species naturally tolerant to acetolactate synthase (ALS) and acetyl-coenzyme A carboxylase (ACCase) inhibiting herbicides. The mechanism of tolerance to ALS herbicides was determined as cytochrome P450-monooxygenase mediated metabolic detoxification. The ALS enzyme extract partially purified from V. bromoides shoot tissue was found to be as sensitive as that of herbicide susceptible Lolium rigidum to ALS-inhibiting sulfonylurea (SU), triazolopyrimidine (TP), and imidazolinone (IM) herbicides. Furthermore, phytotoxicity of the wheat-selective SU herbicide chlorsulfuron was significantly enhanced in vivo in the presence of the known P450 inhibitor malathion. In contract, the biochemical basis of tolerance to ACCase inhibiting herbicides was established as an insensitive ACCase. In vitro ACCase inhibition assays showed that, compared to a herbicide susceptible L. rigidum, the V. bromoides ACCase was moderately (4.5- to 9.5-fold) insensitive to the aryloxyphenoxypropionate (APP) herbicides diclofop, fluazifop, and haloxyfop and highly insensitive (20- to >71-fold) to the cyclohexanedione (CHD) herbicides sethoxydim and tralkoxydim. No differential absorption or de-esterification of fluazifop-P-butyl was observed between the two species at 48 h after herbicide application, and furthermore V. bromoides did not detoxify fluazifop acid as rapidly as susceptible L. rigidum. It is concluded that two co-existing resistance mechanisms, i.e., an enhanced metabolism of ALS herbicides and an insensitive target ACCase, endow natural tolerance to ALS and ACCase inhibiting herbicides in V. bromoides.     

河北省棉花枯萎菌遗传多样性及致病力分化

为明确河北省棉花枯萎菌（Fusarium oxysporum f.sp.vasinfectum, FOV）变异及致病力分化情况,利用AFLP技术对采自河北省的75株FOV和3号、7号、8号生理小种的标准菌株进行遗传多样性分析,并比较了不同AFLP类群菌株对棉花品种冀棉11号的致病力差异。结果表明,78株FOV可划分为4个AFLP类群（AFLP groups, AGs）,AGsⅠ为3号生理小种,AGsⅡ为8号生理小种,AGsⅢ包括7号生理小种和67株田间采集菌株,AGsⅣ包括8个田间采集菌株,该类群菌株与3号、7号、8号生理小种遗传差异较大。致病力初步测定表明,3号、7号、8号生理小种的标准菌株属中等致病力水平,而田间采集的75株枯萎菌菌株致病力存在明显差异,其中强致病力菌株占66.67%,中等致病力菌株占21.33%,弱致病力菌株占12%。表明河北省FOV群体遗传结构复杂,有遗传差异较大的新菌株出现,而且同一生理小种菌株之间存在显著的致病力分化。     

Structure-activity relationships of pheromonostasis induced by ACCase-inhibitor herbicides in the moth Helicoverpa armigera

Many moth sex pheromone blends are derived from fatty acids and their production is regulated by a Pheromone Biosynthesis Activating Neuropeptide (PBAN). In prior work we showed that the herbicide Diclofop-acid, an acetyl-coenzyme A carboxylase (ACCase) inhibitor, inhibits PBAN-induced sex pheromone production in vitro. In this work we extend our study showing that several other herbicides, belonging to the 2-aryloxyphenoxypropionate (‘FOP’) and the cyclohexandione-oxime (‘DIM’) families significantly inhibit pheromone production by adult females whilst survival is unaffected by treatment. Enzyme activity in vitro and kinetic analysis revealed a K_m of 0.35 μM with K_i values of 0.1 and 0.28 μM due to Tralkoxydim and Diclofop inhibition, respectively. Inhibitory activity on PBAN-induced pheromone production by all herbicides tested revealed a potency order: Tralkoxydim > Clodinafop > Cycloxidim > Haloxyfop > Diclofop > Fenoxaprop > Fluazifop > Quizalofop, Quizalofop being inactive. Differences in inhibition efficiencies may be attributed to different binding sites on the enzyme or to the polarity and solubility of these compounds.     

菜豆种子中菜豆普通花叶病毒的RT-PCR检测

为研究国家作物种质库中保存菜豆种质携带种传菜豆普通花叶病毒（BCMV）的状况，根据BCMV的印基因序列设计一对特异性引物，从BCMV侵染的菜豆叶片上扩增出与理论大小一致的714bp的片段。在此基础上，应用改进CTAB法从菜豆干种子中提取总RNA并特异性扩增出相同大小的片段。对目的片段进行克隆、测序和序列同源性比较，结果表明，扩增片段的序列与其它BcMV的印基因序列同源性达88％-98％，确证该方法可以从莱豆干种子申直接检测BCMV。利用建立的方法，分别从单粒菜豆种子样本和30粒菜豆种子样本中检测到BCMV，其检测灵敏度较ELISA方法更高。来自河北的紫芸豆单粒种子带毒率高达100％，而在不同地理来源的6份菜豆种质中，4份被检出携带BCMV，表明入库保存的菜豆种质和种子已普遍为BCMV所侵染。     

甘薯茎腐病的研究进展

甘薯茎腐病是由达旦提狄克氏菌Dickeya dadantii Samson et al.引起的细菌性甘薯病害,属于我国新发生病害,其蔓延迅速、防治困难,严重影响甘薯的品质和产量,已成为我国南方甘薯产区主要病害之一。文章对该病症状、病原菌分类、致病机制、全基因组测序概况和防治措施等方面的研究进展进行了综述,并指出了今后的研究方向。     

苹果锈果类病毒在八棱海棠种子中的分布及氢氧化钠脱毒效果分析

为明确苹果锈果类病毒在八棱海棠果实和种子中的分布特征、种传率以及药剂脱除效果,以带毒母株上的八棱海棠果实和种子为试材,运用RT-PCR技术分析了八棱海棠果实不同部位锈果类病毒的带毒率、实生后代的带毒情况以及氢氧化钠脱除病毒的效果。结果表明,八棱海棠果皮、果肉、种子以及种胚均不同程度携带苹果锈果类病毒,其带毒率分别为96.0%、96.0%、52.0%和4.0%;该病毒可经种子传递给后代,种传率为12.1%;经2%氢氧化钠溶液浸种10、15、20 min,种子的病毒检出率均为0,但后代实生苗的带毒率分别为2.5%、1.3%和0。表明苹果锈果类病毒可侵染种子不同部位并经种子传递给后代,氢氧化钠浸种是脱除该病毒的有效方法。     

Identification of cDNAs induced by the organophosphate trichlorphon in the parasitic copepod Lepeophtheirus salmonis (Copepoda; Caligidae)

Lepeophtheirus salmonis is a copepod ectoparasite of wild and farmed salmonids and can cause considerable damage to infected fish. We have examined the effect of the organophosphate trichlorphon, which was one of the early treatments for sea lice as Neguvon^® on L. salmonis. Suppression subtractive hybridisation was used to prepare a cDNA library enriched for cDNAs expressed in response to the organophosphate trichlorophon and using this technique a total of 33 cDNAs were found to be differentially regulated in response to organophosphate exposure. Sequence analysis of the cDNAs revealed that many were involved in cellular stress responses and or neurotoxicity. The expression of two of these cDNAs was confirmed to be up-regulated in response to trichlorophon.     

中国小麦条锈菌鉴别寄主丰产3号抗条锈性遗传分析

采用常温（昼17℃／夜10℃）和高温（昼24℃／夜15℃）两种温度处理，系统分析了丰产3号抗条锈性遗传基础及抗性特点。研究结果表明，丰产3号至少含有1显1隐2对主效和2对对温度敏感的隐性微效抗条锈基因。其中，2对主效基因互补控制对CY17的抗性，属核遗传；微效基因具有累加效应，高温诱导表达控制对CY26的抗性。当2对主效基因呈隐性纯合时控制0；-1^＋型，1对呈隐性纯合时控制2^--3型，而2对微效基因均呈杂合状态时侵染型为3^＋～4型。系谱分析初步确认，丰产3号控制对CY17抗性的1对显性主效基因来源于丹麦1号，另外1对隐性主效基因则由亲本6028提供。抗性基因等位性分析表明，控制丰产3号对CY17抗性的2对主效基因与Lovrin13（Yr9＋）、VPMI（Yr17）、抗引655（YrKy1，YrKy2）、水源11（YrSu）含有的主效抗条锈基因不同。将丰产3号2对主效抗条锈基因暂定名为YrFcJ和YrFc2。丰产3号作为中国小麦条锈菌鉴别寄主用于抗性鉴定时要严格控制鉴定温度，即不要连续8h超过18cc。