转Bt基因棉田与常规棉田节肢动物群落多样性的比较研究

研究了在棉花生长的早期、中期和后期转Bt(bacillus thuringiensis)基因棉和常规棉两种棉田的节肢动物群落、害虫亚群落和天敌亚群落多样性。结果表明,GK-12未防治区的节肢动物群落多样性指数和害虫亚群落的多样性指数在棉花生长前期和后期要高于泗棉3号未防治区;GK未防治区的天敌亚群落多样性指数在棉花生长后期高于泗棉3号未防治区,在棉花生长的早期和中期,两者的大小没有表现出显著性差异。对影响棉田生态系统3种多样性指数的因子的方差分析表明,棉花品种和化学防治措施的共同作用是影响棉田生态系统节肢动物群落和天敌亚群落多样性指数的主要因子。     

Effect of plant water deficit on the deoxynivalenol concentration in Fusarium-infected maize kernels

In current climate change scenarios, mean air temperatures and summer droughts are expected to increase over the long-term average in large parts of Europe. These changes will strongly affect the growth and health of cultivated plants. In a field experiment in 2009 and 2010 in rain-out shelters, the consequences of plant water availability under three water regimes on the severity of Fusarium ear rot, deoxynivalenol (DON) contamination and yield of maize were investigated. Water was provided exclusively to the plants by a mobile sprinkler system installed in the rain-out shelter. Three maize cultivars were supplied with 50, 75, and 125% of the long-term average monthly precipitation of the experimental site. In 2009, Fusarium graminearum-infected oat kernels were placed on the soil surrounding maize plants to promote ear infection, whereas in 2010, the maize silks were directly inoculated with suspensions of F. graminearum conidia. Heavy drought stress in the 50% water regime was reflected in the average ear yield of the three maize cultivars of 75?dt ha^-1 compared with 192?dt ha^-1 at 125% water. In this comparison, the DON concentrations in the kernels were fivefold higher at 50% water than at the high water regime: 380 compared with 75???g DON kg^-1 DM. In 2010, the drought stress symptoms were less pronounced than in 2009, and a much lower ear yield loss from 128 to 108?dt DM ha^-1 was observed with decreasing water supply. The DON contamination of the kernels was at a higher level than in 2009, but a similar upward trend from 330???g?kg ^-1 DM at 125% water supply to about 3.5-fold higher DON levels at 75 and 50% water supply was observed. These different yield responses presumably resulted from variable climatic conditions at the experimental site in the 2?years. The results of this study suggest that the risk of DON contamination of maize kernels increases when plants are grown under conditions of long-term water deficit.     

Aflatoxin B1, zearalenone and deoxynivalenol production on irradiated corn kernels: Influence of inoculum size

The influence of inoculum size on aflatoxin B₁ (AFB₁), zearalenone (ZEN) and deoxynivalenol (DON) production was examined on irradiated corn kernels. Spore concentrations were determined in serial dilutions and adjusted to 10,10²,10³,10⁵ and 10⁶ spores/ml. Aflatoxin B₁ production was dependent on the inoculum size. The high levels of aflatoxin B₁ produced byA. parasiticus (21 and 30 mg/kg) were obtained with 10² and 10³ spores/ml after 35 and 20 days incubation. There was no spore concentration influence on zearalenone and deoxynivalenol production after 10, 20 and 35 days incubation. At 28°C and 0.97 water activity (aw), the mean levels of zearalenone production were 382, 267 and 520 μg/kg and the mean levels on deoxynivalenol production were 697,465 and 782 μg/kg.     

转Bt基因玉米的生态安全性研究进展

随着转基因作物的应用和推广 ,转 Bt基因作物释放后对生态环境及其它方面产生的潜在影响越来越受到重视。分别从生物活性杀虫晶体蛋白在土壤中的残留特性、杀虫晶体蛋白对土壤中非目标生物的影响、转 Bt基因玉米植株体成分的变化、转Bt基因玉米花粉中杀虫晶体蛋白的表达特性及其在田间和马力筋叶片上的散积状况、花粉中表达的杀虫晶体蛋白对君主斑蝶的毒性、君主斑蝶幼虫暴露在 Bt花粉中的概率及综合风险评价估算等方面对转 Bt基因玉米产生的杀虫晶体蛋白与土壤生态环境的相互作用、花粉对非目标生物影响的研究现状进行了综述。通过对转 Bt基因作物生态安全性的科学评价和广泛宣传 ,以确保生物技术的健康发展。     

Progression of deoxynivalenol and zearalenone concentrations in straw of wheat infected artificially withFusarium culmorum

This investigation aimed at the progression of the contamination of theFusarium toxins deoxynivalenol (DON) and zearalenone (ZON) within the fractions straw, glumes and spindles from non-inoculated andFusarium-inoculated wheat. TheFusarium head blight (FHB)-susceptible wheat cultivar Ritmo was cultivated after the pre-crop maize and artificially infected withFusarium culmorum. Samples of whole wheat plants were taken once a week from anthesis until harvest and fractionated into straw, glumes and spindles. Samples were examined for deoxynivalenol and zearalenone and quantitatively determined by high performance liquid chromatography (HPLC) with diode-array detection (DAD) and fluorescence detection, respectively. Additionally, the impact of theFusarium inoculation on the crude protein content was scrutinised. Differences in the formation of deoxynivalenol and zearalenone with respect to date and concentration are shown by this trial. Deoxynivalenol was produced in higher concentrations and at earlier stages, whereas zearalenone was formed later and in smaller amounts. Furthermore, a rise of the deoxynivalenol concentration up to a maximum during the growing season, followed by a sudden decline at later stages until harvest, was observed. ThisFusarium infection resulted in an increased crude protein content in all of the three fractions.     

人工饲料、转Bt水稻及其亲本稻苗饲养下二化螟种群适合度的比较研究

以人工饲料、转Bt水稻"克螟稻"(cry1Ab纯和基因型)及其对照亲本"秀水11"稻苗为供试寄主植物开展二化螟Chilo suppressalis(Walker)1～5龄幼虫的室内饲养试验,以明确不同龄期二化螟种群的生活史参数。试验结果表明:二化螟在低龄时死亡率最高。克螟稻对二化螟各个龄期表现出高抗性,其各个龄期在克螟稻上均不能化蛹,随着龄期的增加二化螟的耐受性增强。以秀水11和人工饲料饲养二化螟对其蛹期、成虫期、单雌产卵量、羽化率的影响无显著性差异,以人工饲料饲养的二化螟蛹重显著高于以秀水11饲养的二化螟的蛹重,蛹重与人工饲料饲养时间呈正相关。与秀水11幼苗相比,人工饲料饲养下有利于二化螟雌虫的分化。     

Bt转基因玉米的获得及其对玉米螟的抗性分析

以玉米幼胚和愈伤组织为受体,利用基因枪法将Bt基因GFMCry1A导入玉米杂交种“京玉7号(501／京24)”的亲本自交系501中,从转基因高世代材料中筛选出高抗玉米螟的转基因株系T123。T123及其与京24配制的杂交种的田间食叶级别均小于2级,而且也没有观察到玉米螟在茎杆中运动的隧道,表现出高抗玉米螟。     

Fermentation of wort containing deoxynivalenol and zearalenone

Wort containing deoxynivalenol and zearalenone, each added at a level of 1.9 μg/mL, was fermented by 3 strains ofSaccharomyces cerevisiae for 7 or 9 days to make beer. Analysis showed that deoxynivalenol was stable during this process. The major metabolite of zearalenone was β - zearalenol, which formed in up to 69% of the initial zearalenone concentration, while up to 8.1% of the initial zearalenone was converted to α - zearalenol. The major part of the metabolism of zearalenone occurred by 1 – 2 days. Control experiments, where the yeasts were omitted and deoxynivalenol, zearalenone and α - and β - zearalenol were added, showed good recovery and stability of the mycotoxins over the 7–9 day time period. No deoxynivalenol, zearalenone, α-zearalenol or β-zearalenol was detected in control yeast fermentations where they were not added to the wort.     

Aflatoxin B1, zearalenone and deoxynivalenol production by Aspergillus parasiticus and Fusarium graminearum in interactive cultures on irradiated corn kernels

The influence of inoculum size in the production of aflatoxin B1 (AFB1), zearalenone (ZEN) and deoxynivalenol (DON) was determined when Aspergillus parasiticus NRRL 3000 and Fusarium graminearum ITEM 124 were cultured alone and in pairs on irradiated corn kernels at 28 °C and 0.97 water activity (aw). The highest levels of AFB1 produced by A. parasiticus were produced at the lowest levels of the inoculum (103 spores/ml). No significant differences were observed in ZEN and DON production at any inoculum level during the experimental period. When A. parasiticus was co-inoculated with F. graminearum both to the same inocula (106 spores/ml), AFB1 inhibition percentage were 60, 72 and 56% at 10, 20 and 35 days of incubation respectively, while at 106 spores/ml the percentages of inhibition were 34, 84 and 93% at 10, 20 and 35 days. In the mixture cultures A. parasiticus 103 × F. graminearum 106 spores/ml the percentage of inhibition of AFB1 oscillated in 99% during all the incubation. In the interaction A. parasiticus 106 spores/ml × F. graminearum 103 spores/ml the accumulation of AFB1 decreased in 80, 94 and 86% at 10, 20 and 35 days of incubation respectively. In single culture F. graminearum was inoculated with 10³ or 106 spores/ml and the highest levels of ZEN and DON were detected at 35 days of incubation. The levels oscillated in 538–622 μg/kg for ZEN and 870–834 μg/kg for DON respectively. In paired cultures there were no significant differences in the levels regardless of the spore concentrations during the incubation time. This revised version was published online in June 2006 with corrections to the Cover Date.     

Bacterial diversity in rhizospheres of nontransgenic and transgenic corn

Bacterial diversity in transgenic and nontransgenic corn rhizospheres was determined. In greenhouse and field studies, metabolic profiling and molecular analysis of 16S rRNAs differentiated bacterial communities among soil textures but not between corn varieties. We conclude that bacteria in corn rhizospheres are affected more by soil texture than by cultivation of transgenic varieties.     

转Bt基因玉米对根际土壤细菌群落结构的影响

利用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术及扩增产物序列分析方法研究了转Bt基因玉米对根际土壤细菌群落结构及系统发育的影响.结果表明:转基因玉米与其非转基因亲本根际共有的土壤细菌分别隶属于变形菌门、疣微菌门、放线菌门、拟杆菌门、厚壁菌门、芽单胞菌门和酸杆菌门.其中,变形菌门为主要优势类群,占43.5%...     

Field decomposition of transgenic Bt maize residue and the impact on non-target soil invertebrates

The release of chemical compounds from plant roots that suppress soil nitrification is termed biological nitrification inhibition (BNI). Determining the environmental factors that control the synthesis and release of BNI-compounds from Brachiaria humidicola (Rendle) Schweick, a tropical pasture grass that thrives on acid soils, is the focus of this investigation. Because the BNI trait is related to the N status of the plant, we investigated the possibility that the expression of this trait would be related to the forms of N found in the root environment. Plants were grown with two sources of N, NH₄⁺ or NO₃⁻ for 60 days and the release of BNI-compounds monitored. Only plants grown with NH₄⁺ released BNI-compounds from roots. The presence of NH₄⁺ and possibly the secondary effect of its uptake (i.e., acidic pH) in the root environment significantly enhanced the release of BNI-compounds. Both the NH₄⁺ and NO₃⁻ grown plants responded to the stimulus from NH₄⁺ in the root environment. BNI-compounds found in root tissue and their release were nearly three times greater in NH₄⁺ grown than from NO₃⁻ grown plants. The BNI-compounds released from roots composed of at least three active components—Type-I (stable to pH changes from 3.0 to 10), Type-II (temporarily loses its inhibitory effect at a pH higher than a threshold pH of 4.5 and the inhibitory effect is reestablished when the root exudate pH is adjusted to <4.5) and Type-III (inhibitory effect is irreversibly lost if the pH of the root exudate reaches 10.0 or above). A major portion of BNI-compounds released in the presence of NH₄⁺ is of Type-I. In the absence of NH₄⁺, mostly Type-II and Type-III BNI-compounds were released. The BNI-compounds inhibited the function of Nitrosomonas europaea through the blocking of both ammonia monooxygenase and hydroxylamino oxidoreductase pathways. These results indicate that the release of BNI-compounds from B. humidicola roots is a regulated function and that presence of NH₄⁺ in the root environment is necessary for the sustained synthesis and release of BNI.     

Cross-pollination of nontransgenic corn ears with transgenic Bt corn: efficacy against lepidopteran pests and implications for resistance management

The efficacy of nontransgenic sweet corn, Zea mays L., hybrids cross-pollinated by Bacillus thuringiensis (Bt) sweet corn hybrids expressing Cry1Ab toxin was evaluated in both field and laboratory studies in Minnesota in 2000. Non-Bt and Bt hybrids (maternal plants) were cross-pollinated with pollen from both non-Bt and Bt hybrids (paternal plants) to create four crosses. Subsequent crosses were evaluated for efficacy in the field against European corn borer, Ostrinia nubilalis (Hübner), and corn earworm, Helicoverpa zea (Boddie), and in laboratory bioassays against O. nubilalis. Field studies indicated that crosses with maternal Bt plants led to low levels of survival for both O. nubilalis and H. zea compared with the non-Bt x non-Bt cross. However, the cross between non-Bt ears and Bt pollen led to survival rates of 43 and 63% for O. nubilalis and H. zea larvae, respectively. This intermediate level of survival also was reflected in the number of kernels damaged. Laboratory bioassays for O. nubilalis, further confirmed field results with larval survival on kernels from the cross between non-Bt ears and Bt pollen reaching 60% compared with non-Bt crossed with non-Bt. These results suggest that non-Bt refuge plants, when planted in proximity to Bt plants, and cross-pollinated, can result in sublethal exposure of O. nubilalis and H. zea larvae to Bt and may undermine the high-dose/refuge resistance management strategy for corn hybrids expressing Cry1Ab.     

Occurrence of zearalenone in maize

The occurrence of zearalenone in whole plants and parts of maize usually used for silage making was investigated during the cultivation period of the crop. Zearalenone was detected upto several hundreds of μg/kg DM, that mainly accumulated at the end of the ripening process thus contaminating the silages subsequently. The highest concentrations of zearalenone were observed in the leaves especially at the bottom of the plant, which may correlate with leaf necrosis increasing towards harvest. Further research is needed to clarify health risks for farm animals due to uptake of contaminated feed and possible carry-over of zearalenone and its metabolites into the food chain of man.     

Occurrence of deoxynivalenol and zearalenone in brewing barley grains from Brazil

Barley (Hordeum vulgare L.) is an important cereal crop for food and represents one of the main ingredients in beer production. Considering the importance of barley and its derived products, the knowledge about the mycotoxin contamination in the barley production is essential in order to assess its safety. In this study, the levels of deoxynivalenol (DON) and zearalenone (ZEN) in brewing barley were determined using a LC-MS/MS method. A survey was conducted in 2015 to estimate the mycotoxin levels in these products (n?=?76) from four crop regions in Brazil. The results showed high levels of DON and ZEN in the analyzed samples, with contamination levels of 94 and 73.6%, respectively. The mean levels of DON and ZEN ranged from 1700 to 7500 μg/kg and from 300 to 630 μg/kg, respectively. Barley samples from regions 1 and 2 presented higher levels of ZEN and DON, respectively, and those from region 4 presented lower levels of both. Co-occurrence of DON and ZEN was seen in the majority of the barley grain samples, and the mycotoxin content was above the maximum levels established by the Brazilian and European regulations.     

Varietal effects of eight paired lines of transgenic Bt maize and near-isogenic non-Bt maize on soil microbial and nematode community structure

A glasshouse experiment was undertaken to provide baseline data on the variation between conventional maize (Zea mays L.) varieties and genetically modified maize plants expressing the insecticidal Bacillus thuringiensis protein (Bt, Cry1Ab). The objective was to determine whether the variation in soil parameters under a range of conventional maize cultivars exceeded the differences between Bt and non-Bt maize cultivars. Variations in plant growth parameters (shoot and root biomass, percentage carbon, percentage nitrogen), Bt protein concentration in shoots, roots and soil, soil nematode abundance and soil microbial community structure were determined. Eight paired varieties (i.e. varieties genetically modified to express Bt protein and their near-isogenic control varieties) were investigated, together with a Bt variety for which no near-isogenic control was available (NX3622, a combined transformant expressing both Bt and herbicide tolerance) and a conventional barley (Hordeum vulgare L.) variety which was included as a positive control. The only plant parameter which showed a difference between Bt varieties and near-isogenic counterparts was the shoot carbon to nitrogen ratio; this was observed for only two of the eight varieties, and so was not attributable to the Bt trait. There were no detectable differences in the concentration of Bt protein in plant or soil with any of the Bt-expressing varieties. There were significant differences in the abundance of soil nematodes, but this was not related to the Bt trait. Differences in previously published soil nematode studies under Bt maize were smaller than these varietal effects. Soil microbial community structure, as determined by phospholipid fatty acid (PLFA) analysis, was strongly affected by plant growth stage but not by the Bt trait. The experimental addition of purified Cry1Ab protein to soil confirmed that, at ecologically relevant concentrations, there were no measurable effects on microbial community structure.     

Expression of Bt cry1Ac in transgenic oilseed rape in China and transgenic performance of intraspecific hybrids against Helicoverpa armigera larvae

The expression of a synthetic Bacillus thuringiensis ( Bt ) cry1Ac gene in oilseed rape (OSR, Brassica napus ) was monitored under field conditions in China, and performance against Helicoverpa armigera larvae was compared in intraspecific hybrids with a Chinese OSR variety. Leaf samples from transgenic OSR were collected at various developmental stages in two separate field experiments. The Bt Cry1Ac concentrations in the third uppermost leaves increased before pod formation stage and either increased or decreased after pod formation stage whereas the total soluble protein increased before and decreased after pod-fill in the later growing season. Spontaneously formed intraspecific hybrids between transgenic OSR and a Chinese conventional OSR were obtained in the field and transgenic status was confirmed by a green fluorescent protein (GFP) phenotype and polymerase chain reaction. A bioassay on the neonate larvae of a susceptible strain of H.   armigera was performed to test the efficacy of Bt Cry1Ac toxin in hybrid OSR plants. Both the original transgenic OSR and hybrid plants had a negative effect on body-weight gain of insect larvae. It was assumed that Bt Cry1Ac toxin concentration was similar in hybrids compared to the original transgenic OSR at the investigated developmental stages. The frequency of hybrid production and volunteerism could potentially enhance the evolution of insect pest tolerance in the field.     

Cotton boll abscission and yield losses associated with first-instar bollworm (Lepidoptera: Noctuidae) injury to nontransgenic and transgenic Bt cotton

Field tests were conducted in northeastern Louisiana to determine the effects of infestations by Helicoverpa zea (Boddie) on cotton bolls of varying ages. First instars were caged on bolls of nontransgenic ('Deltapine 5415') or transgenic Bacillus thuringiensis Berliner variety kurstaki (Bt) ('NuCOTN 33B') cotton from 29 June to 11 August during 1997 and 1998. Deltapine 5415 bolls that accumulated 179 (7.2 d), 281 (11.2 d), and 253 (10.1 d) heat units beyond anthesis were safe from bollworm-induced abscission at 72 h after infestation, 7 d after infestation, and at the time of harvest, respectively. NuCOTN 33B bolls that accumulated 157 (6.3 d), 185 (7.4 d), and 180 (7.2 d) heat units beyond anthesis were safe from bollworm-induced abscission at 72 h after infestation, 7 d after infestation, and at the time of harvest, respectively. Bollworm larvae reduced seedcotton weights of Deltapine 5415 bolls that accumulated between 58.5 (2.3 d) and 350.5 (14.0 d) heat units beyond anthesis. Seedcotton weights of NuCOTN 33B bolls that accumulated between 0 and 281 (11.2 d) heat units beyond anthesis were reduced by bollworm injury. Deltapine 5415 and NuCOTN 33B bolls that accumulated 426.5 (17.1 d) and 299.5 (12.0 d) heat units beyond anthesis, respectively, before infestation were not injured by first-instar bollworm larvae. These data provide information about late-season insecticide termination strategies for bollworms on nontransgenic and transgenic Bt-cotton. This, in turn, will help pest managers determine when insecticides are no longer economical during the late season.     

Effects of deoxynivalenol and zearalenone on oxidative stress and blood phagocytic activity in broilers

Effects of dietary contamination with various levels of deoxynivalenol (DON) and zearalenone (ZEA) were investigated on Ross 308 hybrid broilers of both sexes. After hatching, all chickens were fed an identical control diet for two weeks. Then chickens of Group 1 received a diet contaminated with DON and ZEA, both being 3.4 mg kg(-1), while Group 2 received DON and ZEA at 8.2 and 8.3 mg kg(-1), respectively. The diet of the control group contained background levels of mycotoxins. Samples of blood and tissues were collected after two weeks. Intake of both contaminated diets resulted in a significantly decreased activity of glutathione peroxidase (GPx) and increased level of malondialdehyde (MDA) in liver tissue, while in kidneys the concentration of MDA was significantly increased only in Group 1. On the other hand, activities of blood GPx and plasma gamma-glutamyltransferase (GGT) were elevated in Group 2 only. Activities of thioredoxin reductase in liver and GPx in duodenal mucosa tissues, superoxide dismutase (SOD) in erythrocytes as well as levels of MDA in duodenal mucosa and alpha-tocopherol in plasma were not affected by dietary mycotoxins. Blood phagocytic activity was significantly depressed in Group 1 and 2. These results demonstrate that diets contaminated with DON and ZEA at medium levels are already able to induce oxidative stress and compromise the blood phagocytic activity in fattening chickens.