纳米农药在植物中的吸收转运研究进展

农药是一类用于防治作物病虫草害、保障粮食生产与安全的化学物质。传统农药剂型载药粒子粒径粗大, 有效利用率低, 用量大, 对生态环境造成严重危害。农药纳米剂型可以提高载药系统的分散性、稳定性及生物活性, 是克服传统剂型功能缺陷、提高农药有效利用率、减少环境污染的重要科学途径。研究纳米农药粒子在植物体内的吸收与转运行为, 对于理解纳米农药与植物的互作方式, 揭示其在植物体内的吸收作用机制及生物累积效应, 以及明确其生物安全性具有重要意义。该文从纳米农药在植物体内的吸收转运影响因素、机制、分析方法及其生物安全性4个方面进行综述, 阐明了无机和有机纳米农药在植物体内的吸收转运模式及研究手段, 并展望了其应用前景, 以期为纳米农药的设计、构建及合理安全使用提供理论与技术支撑。     

阿维菌素B1a对土壤微生物和蚯蚓的影响

研究了不同阿维菌素B_1a浓度对种土壤微生物生长和呼吸强度的影响及对土壤中蚯蚓的急性毒性.结果表明,土壤中阿维菌素B_1a浓度在83.3 mg·kg^-1以上时对种土壤细菌均表现出明显的抑制作用,但对土壤真菌不表现抑制作用.高浓度阿维菌素B_1a对土壤微生物的呼吸强度有抑制作用,并且在不同土壤其作用有差异.采用滤纸接触试验和人工土壤试验测定阿维菌素对蚯蚓的急性毒性(半数致死量,LD₅₀),接触毒性LD₅₀为.63μg·cm^-2,土壤法试验测定的LD₅₀在处理后第7 d和第1 d分别为2.13和17.06 mg·kg^-1.     

Fabrication of curcumin-loaded zein nanoparticles stabilized by sodium caseinate/sodium alginate: Curcumin solubility,thermal properties,rheology, and stability

Curcumin is a polyphenol with multiple biological activities, but its extremely poor water solubility severely limits its application in the food industry. The purposes of this work were to study the effect of nano-encapsulation on the water solubility of curcumin (C), the interaction of curcumin with zein (Z), the thermal properties, rheological properties, and the stability under different environmental pressures of the nanoparticles. The results of particle size, zeta potential, and surface hydrophobicity (H₀) indicated that the combination of coating materials including sodium caseinate (SC) and sodium alginate (SA) with zein nanoparticles by electrostatic interaction led to a gradual increase in the particle size of composite nanoparticles and a decrease in surface hydrophobicity. The nano-encapsulation significantly improved the water solubility of curcumin and causing its crystal structure to change to an amorphous state. Fourier transform infrared spectroscopy confirmed that curcumin bound to zein through hydrogen bonding. Rheological test results showed that the coating materials combined with zein led to an increase in the apparent viscosity of the nanoparticles. The stability analysis results indicated that the composite nanoparticles with a sodium alginate coating have excellent stability of pH, salt solution and storage, and excellent anti-gastrointestinal fluids digestion characteristics when compared to pure protein nanoparticles.     

Detection of resistance to ivermectin in Haemonchus contortus.

Infective, third-stage (L3) larvae of Haemonchus contortus isolates resistant to ivermectin (IVM) show a decreased sensitivity to IVM-induced paralysis in vitro. The inhibition of larval motility by IVM can be detected in L3 larvae incubated in the dark on an agar matrix containing IVM, by the failure of affected larvae to move when stimulated by exposure to light. Optimally, avermectin (AVM) potency is quantified after three cycles, each involving storage in the dark for 24 h followed by a brief exposure to light. For IVM-susceptible isolates, a 50% inhibition of motility (LP50) was achieved with IVM concentrations between 0.30 and 0.49 microM, while LP50 values in IVM-resistant isolates ranged from 0.8 to 2.6 microM depending on the in vivo resistance status of the isolate. A limited study of structure-activity relationships within the AVM class indicated that in vitro inhibition of L3 motility was consistent with the known in vivo efficacy of each analogue. Resistance factors for IVM-resistant isolates were dependent on AVM structure with the more polar AVM B2 analogue being a particularly sensitive probe of IVM-resistance status.     

5种杀螨剂对不同螨态荔枝叶螨的毒力评价和田间防效

为了综合评价常用杀螨剂对荔枝叶螨Oligonychus litchii的室内毒力,在室内分别采用Potter喷雾法、浸叶碟法和浸叶法测定了5种常用杀螨剂对荔枝叶螨成螨、卵和若螨的毒力,并测定了5种杀螨剂对荔枝叶螨的田间防效。室内毒力结果表明:哒螨灵、阿维菌素对荔枝叶螨成螨和若螨有较高的毒力,联苯肼酯对成螨和若螨的毒力较低,而螺螨酯和乙螨唑对成螨基本无活性,对若螨有一定的毒力;5种杀螨剂对卵的毒力大小依次为乙螨唑螺螨酯哒螨灵阿维菌素联苯肼酯。田间防效试验中,15%哒螨灵乳油和1.8%阿维菌素乳油对荔枝叶螨的总体防效较好,药后1 d防效高于70%,药后10 d防效达100%,药后20 d防效仍在90%以上,速效性和持效性均较好;240 g/L螺螨酯悬浮剂和110 g/L乙螨唑悬浮剂对荔枝叶螨药后3 d防效均低于70%,而药后20 d的防效高于90%,说明两药剂速效性较差但持效性较好;43%联苯肼酯悬浮剂药后1、3 d防效低于阿维菌素和哒螨灵,高于螺螨酯和乙螨唑,药后15 d防效开始下降。在田间防治荔枝叶螨时,若荔枝叶螨发生早期、成螨较少时建议施用螺螨酯或乙螨唑,而荔枝叶螨种群中成螨、若螨较多时推荐施用阿维菌素、哒螨灵或联苯肼酯。     

广州市鸭脚树星室木虱调查及其防治药剂筛选

以广州市糖胶树上的鸭脚树星室木虱为对象,调查其发生和为害特点,并选用0.5%印楝素、阿维·啶虫脒、3%啶虫脒和20%吡虫啉共4种低毒高效农药进行室内毒力试验和防治试验。结果表明,广州市鸭脚树星室木虱发现普遍、危害严重。0.5%印楝素、阿维·啶虫脒和3%啶虫脒对鸭脚树星室木虱若虫的室内杀虫效果较好,20%吡虫啉则较差。林间施药0.5%印楝素、阿维·啶虫脒和3%啶虫脒20d后,鸭脚树星室木虱若虫的死亡率均达63%以上。结合害虫综合治理和环境生态保护的实际情况,建议使用0.5%印楝素对鸭脚树星室木虱若虫进行防治。     

截形叶螨对哒螨灵、阿维菌素和阿维·哒螨灵的抗性选育和抗性稳定性研究

【目的】明确截形叶螨Tetranychus truncatus Ehara对哒螨灵、阿维菌素和阿维·哒螨灵3种田间常用药剂产生抗性的速率和稳定性,为叶螨的抗性综合治理提供一定的理论依据。【方法】采用室内生测法,对截形叶螨进行药剂的抗性筛选、衰退和再恢复规律研究。【结果】经过连续30代的药剂汰选,截形叶螨对哒螨灵、阿维菌素和阿维·哒螨灵3种药剂产生了不同程度的抗药性,抗性指数分别达到197.50、19.56和12.57;停止喷药后,其抗性都有所下降,其中截形叶螨对哒螨灵的抗性最不稳定,培育至30代后,抗性衰退率达到63.54%,对阿维菌素的抗性较为稳定,抗性衰退率为23.30%;再次恢复用药后,截形叶螨对哒螨灵、阿维菌素和阿维哒螨灵抗性再度回升,以抗哒螨灵品系的抗性恢复最快,药剂汰选30代后,增长率达到了58.47%,阿维·哒螨灵次之(增长率为38.67%),抗阿维菌素的品系抗性恢复最慢,增长率仅为22.86%。【结论】截形叶螨对哒螨灵抗性不稳定,停止用药后,敏感性易恢复,对阿维菌素和阿维·哒螨灵的抗性较稳定,一旦抗性产生不易衰退,故田间应用时应交替轮换用药。     

Influence of formulation additives on the desiccation tolerance and storage stability of blastospores of the entomopathogenic fungus Paecilomyces fumosoroseus (Deuteromycotina: Hyphomycetes)

Blastospores of the entomopathogenic fungus Paecilomyces fumosoroseus were formulated with 10% lactose/1% bovine serum albumin (BSA) or various compositions of Fantesk™, a starch-oil composite prepared by jet-cooking an aqueous dispersion of starch and oil. Storage stability studies with wet blastospore formulations showed that maximum blastospore survival was achieved during low-temperature storage at -20°C with lactose/BSA formulations or starch-oil formulations supplemented with sucrose, zein protein, and whole milk. Under conditions of wet storage at -20°C, the addition of whole milk to starch-oil formulations significantly improved blastospore stability while the addition of sucrose or zein protein had no effect. In freeze-drying studies, no significant differences were seen in blastospore desiccation tolerance or in stability during storage at either 4 or -20°C when blastospores of P. fumosoroseus were formulated with lactose/BSA or starch-oil formulations with sucrose, zein protein, and whole milk. Freeze-dried blastospore formulations stored at 4°C showed no loss in blastospore viability after 3 months storage and blastospore formulations stored at -20°C showed no loss in viability during the entire 12-month study. For freeze-dried, starch-oil formulations, sucrose was shown to improve blastospore survival during the freeze-drying process. The addition of whole milk to starch-oil formulations significantly improved the stability of freeze-dried blastospores stored at 4°C. Compared to unformulated blastospore suspensions that showed blastospore settling after 30 min, suspensions of blastospores formulated with lactose/BSA or starch-oil composites remained stable for up to 2 h after mixing.     

Toxicity of pesticides to the citrus leafminer and its parasitoid Ageniaspis citricola evaluated to assess their suitability for an IPM program in citrus nurseries

The relative toxicity of pesticides to Phyllocnistis citrella and its parasitoid Ageniaspis citricola was compared by several bioassay methods. A clip-cage bioassay measured survival of adults exposed to fresh residues at 0.25-times (0.25×), 0.5×, 1×, and 2× the lowest recommended rate of each pesticide, a water control (0×), and 24- and 48-h aged residues of oil at 1.5% (1×) rate. A one-species cylinder bioassay determined the effects of pesticides on immature stages of the citrus leafminer after treating young citrus trees with the same rates of pesticides (except for avermectin, tested at 0×, 0.01×, 0.025×, 0.05×, 0.1×, and 0.25× rates). A sublethal rate of petroleum oil (0.4%) was added as an adjuvant in some treatments. The effect of pesticides on immature stages of A. citricola was determined with a two-species cylinder bioassay after treating young citrus trees with the same rates as above. An index of IPM compatibility was developed based on the efficacy of the pesticide as a control agent of the leafminer (or other pests) and its selectivity to the parasitoid at the lowest recommended field rate (0.25× the field rate for avermectin). Azadirachtin (Neemix) + oil, diflubenzuron (Micromite) + oil, fenoxycarb (Eclipse) + oil, and oil alone (FC 435-66) were classified as IPM-compatible insecticides. Sprays of azadirachtin (Align) + oil, neem oil (Neemgard), and drenched imidacloprid (Admire) were ranked as a semi-compatible insecticides. The fungicide copper hydroxide (Kocide 101) and a fish oil-based foliar fertilizer (Zapata HFE) were considered compatible. Avermectin (Agri-Mek) + oil, ethion (Ethion), and imidacloprid (Provado) applied as a spray were IPM-incompatible insecticides. These products should be tested under field conditions to confirm these ratings.     

阿维菌素B1a组分高产菌株的定向选育

以阿维链霉菌(Streptomyces avermitilis)1-17为出发菌株,分别使用紫外线及亚硝基胍并结合L-异亮氨酸诱导手段进行诱变处理,得到AVMB1a组分摇瓶发酵水平较出发菌株提高12.86%的突变株3-6.传代实验表明该菌株的高产性能稳定.结果表明,采用UV、NTG诱变结合L-Ile诱导的手段可以获得B1a组分显著提高的菌株.     

Nanoencapsulation of Rose-Hip Oil Prevents Oil Oxidation and Allows Obtainment of Gel and Film Topical Formulations

The rose-hip oil holds skin regenerating properties with applications in the dermatological and cosmetic area. Its nanoencapsulation might favor the oil stability and its incorporation into hydrophilic formulations, besides increasing the contact with the skin and prolonging its effect. The aim of the present investigation was to develop suitable rose-hip-oil-loaded nanocapsules, to verify the nanocapsule effect on the UV-induced oxidation of the oil and to obtain topical formulations by the incorporation of the nanocapsules into chitosan gel and film. The rose-hip oil (500 or 600 μL), polymer (Eudragit RS100®, 100 or 200 mg), and acetone (50 or 100 mL) contents were separately varied aiming to obtain an adequate size distribution. The results led to a combination of the factors acetone and oil. The developed formulation showed average diameter of 158?±?6 nm with low polydispersity, pH of 5.8?±?0.9, zeta potential of +9.8?±?1.5 mV, rose-hip oil content of 54?±?1 μL/mL and tendency to reversible creaming. No differences were observed in the nanocapsules properties after storage. The nanoencapsulation of rose-hip oil decreased the UVA and UVC oxidation of the oil. The chitosan gel and film containing rose-hip-oil-loaded nanocapsules showed suitable properties for cutaneous use. In conclusion, it was possible to successfully obtain rose-hip-oil-loaded nanocapsules and to confirm the nanocapsules effect in protecting the oil from the UV rays. The chitosan gel and film were considered interesting alternatives for incorporating the nanoencapsulated rose-hip oil, combining the advantages of the nanoparticles to the advantages of chitosan.     

Influence of Formulation Factors on the Preparation of Zein Nanoparticles

The main objective of the present study was to investigate the influence of various formulation parameters on the preparation of zein nanoparticles. 6,7-dihydroxycoumarin (DHC) was used as a model hydrophobic compound. The influence of pH of the aqueous phase, buffer type, ionic strength, surfactant, and zein concentration on particle size, polydispersity index, and zeta potential of DHC-loaded zein nanoparticles were studied. Smaller nanoparticles were formed when the pH was close to the isoelectric point of zein. DHC-loaded zein nanoparticles prepared using citrate buffer (pH 7.4) was better than phosphate buffer in preventing particle aggregation during lyophilization. The ionic strength did not have a significant influence on the particle size of DHC-loaded zein nanoparticles. A combination of Pluronic F68 and lecithin in 2:1 ratio stabilized the zein nanoparticles. An increase in zein concentration led to increase in particle size of DHC-loaded zein nanoparticles. The use of optimal conditions produced DHC-loaded nanoparticles of 256 ± 30 nm and an encapsulation efficiency of 78 ± 7%. Overall, the study demonstrated the optimal conditions to prepare zein nanoparticles for drug encapsulation.KEY WORDS: drug delivery, particle size distribution, pH nanoprecipitation, protein polymers, zein, zeta potential     

Separation,antitumor activities,and encapsulation of polypeptide from Chlorella pyrenoidosa

Chlorella pyrenoidosa is a unicellular green algae and has been a popular foodstuff worldwide. However, no reports on the antitumor peptides from such a microalgae are available in the literature. In this study, using low‐temperature high‐pressure extraction, enzymatic hydrolysis, ion exchange, and gel filtration chromatography, we separated a polypeptide that exhibited inhibitory activity on human liver cancer HepG2 cells, and named the polypeptide CPAP (C. pyrenoidosa antitumor polypeptide). Furthermore, the micro‐ and nanoencapsulation of CPAP were investigated by using two methods: complex coacervation and ionotropic gelation. The in vitro release tests revealed that CPAP was well preserved against gastric enzymatic degradation after micro/nanoencapsulation and the slowly controlled release in the intestine could be potentially achieved. These results suggest that CPAP may be a useful ingredient in food, nutraceutical, and pharmaceutical applications. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:681–687, 2013     

Protein accumulation and rumen stability of wheat γ‐gliadin fusion proteins in tobacco and alfalfa

The nutritional value of various crops can be improved by engineering plants to produce high levels of proteins. For example, because methionine deficiency limits the protein quality of Medicago Sativa (alfalfa) forage, producing alfalfa plants that accumulate high levels of a methionine‐rich protein could increase the nutritional value of that crop. We used three strategies in designing methionine‐rich recombinant proteins that could accumulate to high levels in plants and thereby serve as candidates for improving the protein quality of alfalfa forage. In tobacco, two fusion proteins, γ‐gliadin‐δ‐zein and γ‐δ‐zein, as well as δ‐zein co‐expressed with β‐zein, all formed protein bodies. However, the γ‐gliadin‐δ‐zein fusion protein accumulated to the highest level, representing up to 1.5% of total soluble protein (TSP) in one transformant. In alfalfa, γ‐gliadin‐δ‐zein accumulated to 0.2% of TSP, and in an in vitro rumen digestion assay, γ‐gliadin‐δ‐zein was more resistant to microbial degradation than Rubisco. Additionally, although it did not form protein bodies, a γ‐gliadin‐GFP fusion protein accumulated to much higher levels, 7% of TSP, than a recombinant protein comprised of an ER localization signal fused to GFP in tobacco. Based on our results, we conclude that γ‐gliadin‐δ‐zein is a potential candidate protein to use for enhancing methionine levels in plants and for improving rumen stability of forage protein. γ‐gliadin fusion proteins may provide a general platform for increasing the accumulation of recombinant proteins in transgenic plants.     

Actions of avermectin B1a on the gamma-aminobutyric acidA receptor and chloride channels in rat brain

The interaction of avermectin B1a (AVM) with the gamma-aminobutyric acid (GABA) receptor of rat brain was studied using radioactive ligand binding and tracer ion flux assays. Avermectin potentiated the binding of [3H]flunitrazepam and inhibited the binding of both [3H]muscimol and [35S]t-butylbicyclophosphorothionate to the GABAA receptor. Inhibition of muscimol binding by AVM suggested competitive displacement. Two kinds of 36chloride (Cl) flux were studied. The 36Cl efflux from preloaded microsacs was potentiated by AVM and was highly inhibited by the Cl-channel blocker 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS). However, it was not potentiated by GABA nor was it sensitive to the convulsants picrotoxin or bicuculline. On the other hand, 36Cl-influx measurement in a different microsac preparation of rat brain was very sensitive to GABA and other GABA-ergic drugs. Avermectin induced 36Cl influx into these microsacs in a dose-dependent manner, but to only 35% of the maximal influx induced by GABA. The AVM-induced 36Cl influx was totally blocked by bicuculline. It is suggested that AVM opens the GABAA-receptor Cl channel by binding to the GABA recognition site and acting as a partial receptor agonist, and also opens a voltage-dependent Cl channel which is totally insensitive to GABA but is very sensitive to DIDS.     

Effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing yellow zein

The Freundlich model was evaluated for use to assess the effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing corn zein. Because zein protein and its color/odor components are all adsorbed by activated carbon, a method to monitor their removal was needed. Yellow color is due to xanthophylls; a contributor to off-odor is diferuloylputrescine. The off-odor component absorbs ultraviolet (UV) light at about 325 nm and its removal coincides with removal of yellow color. A spectrophotometric method based on UV absorbances 280 nm for protein and 325 nm for the off-odor component was used to monitor their adsorptions onto activated carbon. Equilibrium studies were performed over temperature range from 25 to 60 degrees C for zein dissolved in 70% aqueous ethanol. Runs made at 55 degrees C adsorbed significantly more of the color/odor components than the protein.     

三种纳米缓释剂农药对葱蓟马的田间药效评价

葱蓟马Thrips tabaci Lindeman是一种世界性农业害虫,为明确3种纳米缓释剂农药对葱蓟马的防治效果,开展了田间药效评价试验.结果表明,0.7％甲维盐纳米缓释剂(NR)和5％甲维盐微乳剂(ME)对葱蓟马的速效性和持效性较好,3～14 d的防效均达到90％以上;10％高效氯氟氰菊酯NR和5％高效氯氟氰菊酯M...     

四种生物农药及其与二种化学农药混配对稻飞虱混合种群的防治效果

试验以喷雾法研究4种生物农药及其与2种化学农药组合混用对水稻褐飞虱Nilaparvata lugens(Stal)和白背飞虱Sogatella furcifera(Horvath)混合种群的防治效果。结果表明:0.36%苦参碱AS、0.5%藜芦碱WP、1.8%阿维菌素EC、400亿孢子/克白僵菌WP,分别以1500mL/hm2、3000g/hm2、900mL/hm2、1800g/hm2的制剂用量单独使用,只有阿维菌素效果较好,药后7、14d的防效分别达到了73.3%和82.3%,但与对照药剂48%毒死蜱EC1500mL/hm2和25%噻嗪酮WP750g/hm2的防效差异极显著。而4种生物农药与2种化学农药分别以单用剂量减半混合使用的8个处理中,①苦参碱+毒死蜱、②藜芦碱+毒死蜱、③阿维菌素+毒死蜱、④球孢白僵菌+毒死蜱、⑤苦参碱+噻嗪酮、⑥藜芦碱+噻嗪酮6种组配,药后1d的校正防效为81.8%～89.2%,3d为88.2%～96.5%,7d为95.6%～98.1%,14d为86.0%～97.8%。因此,以上生物农药与化学农药的6种组合混用可以有效防治稻飞虱低龄若虫。