Chronic Responses of Daphnia magna Under Dietary Exposure to Leaves of a Transgenic (Event MON810) Bt-Maize Hybrid and its Conventional Near-Isoline

Novel Field-Based Protein Detection Method Using Light Transmission Spectroscopy and Antibody Functionalized Gold Nanoparticles

Protein detection is a universal tool critical to many applications in medicine, agriculture, and biotechnology. We developed a novel protein detection method combining light transmission spectroscopy and particle-size analysis of gold nanospheres monovalently functionalized with polyclonal antibodies and applied it to an emerging challenge for such technologies─the monitoring of environmental proteins (eProteins) present in natural aquatic systems. These are an underreported source of pollution and include the pseudopersistent Cry toxins that enter aquatic ecosystems from surrounding genetically engineered crops. The assay is capable of detecting proteins in complex matrices, such as water samples collected in the field, making it a competitive assay for eProtein detection. It is sensitive, reaching 1.25 ng mL^-1, and we demonstrate its application to the detection of Cry1Ab from subsurface tile-drain and streamwater samples from agricultural waterways. The assay can also be quickly adapted for other protein detection applications in the future.

Environmental fate of Bt proteins in soil: Transport, adsorption/desorption and degradation

During the production and application of Bacillus thuringiensis (Bt) transgenic crops, large doses of insecticidal Bt toxic proteins are expressed continuously. The multi-interfacial behaviors of Bt proteins entering the environment in multi-media affects their states of existence transformation, transport and fate as well as biological and ecological impacts. Because both soil matrix and organisms will be exposed to Bt proteins to a certain extent, knowledge of the multi-interfacial behaviors and affecting factors of Bt proteins are vital not only for understanding the source-sink distribution mechanisms, predicting their bio-availability, but also for exploring the soil safety and environmental problems caused by the interaction between Bt proteins and soil matrix. This review summarized and analyzed various internal and external factors that affect the adsorption/ desorption and degradation of Bt proteins in the environment, so as to understand the multi-interfacial behaviors of Bt proteins. In addition, the reasons of concentration changes of Bt proteins in soil are discussed. This review will also discuss the existing knowledge of the combined effects of Bt proteins and other pollutants in environment. Finally, discussing the factors that should be considered when assessing the environmental risk of Bt proteins, thus to further improve the understanding of the environmental fate of Bt proteins.

Addressing the challenges of non-target feeding studies with genetically engineered plant material - stacked Bt maize and Daphnia magna

Previous studies reported adverse effects of genetically engineered maize that produces insecticidal Cry proteins from Bacillus thuringiensis (Bt) on the water flea Daphnia magna. In the current study, effects of flour, leaves, or pollen from stacked Bt maize that contains six Bt proteins (SmartStax) in two plant backgrounds on life table parameters of D. magna were investigated. Adverse effects were observed for Bt maize flour, originating from different production fields and years, but not for leaves or pollen, produced from plants grown concurrently in a glasshouse. Because leaves contained eight to ten times more Cry protein than flour, the effects of the flour were probably not caused by the Cry proteins, but by compositional differences between the plant backgrounds. Furthermore, considering the natural range of variation in the response of D. magna to conventional maize lines, the observed effects of Bt maize flour were unlikely to be of biological relevance. Our study demonstrates how Cry protein effects can be separated from plant background effects in non-target studies using Bt plant material as the test substance and how detected effects can be judged for their biological relevance.

Use of High-Performance Liquid Chromatography-Mass Spectrometry of Adipose Tissue for Detection of Bioaccumulation of Pyriproxyfen in Adults of Lithobates catesbeianus

The aims of the study were: (i) evaluate the efficacy of using amphibian adipose tissue as a valid biomarker of water contaminated by pyriproxyfen; and (ii) verify the use of Lithobates catesbeianus in laboratory experiments as a potential bioindicator for bioaccumulation of pesticide in adipose tissue from amphibians. Adult frogs were exposed to different dilutions (0.002 g/L and 0.02 g/L) of Sumilarv® (pyriproxyfen) over 50 days. The average results of the fortified sample were 108%, indicating that the test method was effective. Adult frogs exposed to the standard dose recommended by the World Health Organization (WHO) showed bioaccumulation of pyriproxyfen in adipose tissue significantly higher than control animals. Lithobates catesbeianus proved to be an effective bioindicator and the adipose tissue was an efficient biomarker to bioaccumulation of pyriproxyfen. We conclude that high-performance liquid chromatography-mass spectrometry was effective measuring pyriproxyfen bioaccumulation in adult amphibians.

Performance of Daphnia magna on flour, leaves, and pollen from different maize lines: Implications for risk assessment of genetically engineered crops

Non-target effects of genetically engineered (GE) plants on aquatic Daphnia magna have been studied by feeding the species with different maize materials containing insecticidal Cry proteins from Bacillus thuringiensis (Bt). The results of those studies were often difficult to interpret, because only one GE plant was compared to one related non-GE control. In such a setting, effects of the Cry proteins cannot be distinguished from plant background effects, in particular when the test species is nutritionally stressed. In the present study, we tested the suitability of three different maize materials, i.e., flour, leaves and pollen, from five diverse non-GE maize lines (including EXP 258, a breeding line that is closely related to a SmartStax Bt maize) as exclusive food sources for D. magna. The parameters recorded included survival, sublethal endpoints such as body size, number of moltings to first offspring, time to first offspring, number of individuals in first clutch, total number of clutches, total number of offspring, average number of offspring per clutch, and population measures such as net reproductive rate R₀, generation time T and intrinsic rate of increase r_m. The results showed that D. magna can survive, grow and reproduce when fed only maize materials, although the performance was poorer than when fed algae, which indicates nutritional stress. Large differences in life table and population parameters of D. magna were observed among the different maize lines. Our results suggest that confounding effects caused by nutritional stress and plant background might explain some of the conflicting results previously published on the effects of Bt crops on D. magna. Using 95% confidence intervals for the means of the five maize lines for all measured parameters of D. magna performance in our study, we captured the natural range of variation. This information is useful for the interpretation of observed differences in D. magna performance between a GE plant and its non-GE comparator as it helps judging whether observed effects are of biological relevance. If differences between a GE and comparator line are observed and their biological relevance needs to be assessed in future risk assessments of GE maize, 1) the data on natural variation of the different parameters generated by previous studies can be informative (e.g. data from our study for maize fed D. magna); 2) for additional experiments the inclusion of multiple unrelated non-GE comparators should be considered; In addition, it should be taken into account that nutritional stress can affect the outcome of the study.

Effect of Bt toxin Cry1Ab on two freshwater caddisfly shredders - an attempt to establish dose-effect relationships through food-spiking

Genetically modified organisms (GMOs), which produce Bacillus thuringiensis (Bt) toxins, are widely used in agriculture in some parts of the world. Despite this, ecotoxicological methods, tailored to GMOs, are lacking to assess effects on aquatic environments. With the objective to investigate a food-related exposure pathway for aquatic shredders, we used a new food-spiking method while caddisfly larvae (Chaetopteryx spec., Sericostoma spec.) served as test species. Pure Cry1Ab toxins were spiked on black alder leaf discs and subsequently used in a feeding experiment. The toxin did not influence larval mortality compared to the control. The results, however, showed significant effects on larval lipid content (Chaetopteryx spec.) and development (Sericostoma spec.) at concentrations of 17.2 and 132.4 ng Cry1Ab/mg leaf, respectively. These changes are indicative for impacts on the fitness of the specimen and thus relevant in a risk assessment context. Ultimately, the food-spiking method allowed applying different Bt toxin concentrations leading to the establishment of dose-response relationships for various response variables. The use of long test durations and sublethal endpoints (consumption, lipid content, growth, larval instars) is, moreover, advisable when testing GMO effects.

Effects of straw leachates from Cry1C-expressing transgenic rice on the development and reproduction of Daphnia magna

The transgenic rice line T1C-19 provides high resistance to lepidopteran pests because of the synthesis of the Bacillus thuringiensis (Bt) insecticidal protein Cry1C. It thus shows good prospect for commercial planting in China. Species of Cladocera, an order of aquatic arthropods commonly found in aquatic ecosystems such as rice paddies, might be exposed to the insecticidal protein released from Bt-transgenic rice-straw residues. For the study reported herein, we used Daphnia magna (water flea) as a representative of Cladocera to evaluate whether aquatic arthropods are adversely affected when exposed to Bt rice-straw leachates. We exposed D. magna to M4 medium containing various volume percentages of medium that had been incubated with T1C-19 rice straw or rice straw from its non-transformed near-isoline Minghui 63 (MH63) for 21 days. Compared with pure M4 medium (control), the fitness and developmental and reproduction parameters of D. magna decreased significantly when exposed to rice-straw leachates; conversely, no significant differences between the T1C-19 and MH63 rice-straw leachate treatments were observed, indicating that the Bt rice straw leachate did not adversely affect this non-target species.

Impact of genetically modified organisms on aquatic environments: Review of available data for the risk assessment

The aquatic environment is strongly connected to the surrounding agricultural landscapes, which regularly serve as sources of stressors such as agrochemicals. Genetically modified crops, which are cultivated on a large scale in many countries, may also act as stressors. Despite the commercial use of genetically modified organisms (GMOs) for over 20years, their impact on the aquatic environment came into focus only 10years ago. We present the status quo of the available scientific data in order to provide an input for informed aquatic risk assessment of GMOs. We could identify only 39 publications, including 84 studies, dealing with GMOs in the aquatic environment, and our analysis shows substantial knowledge gaps. The available information is restricted to a small number of crop plants, traits, events, and test organisms. The analysis of effect studies reveals that only a narrow range of organisms has been tested and that studies on combinatorial actions of stressors are virtually absent. The analysis of fate studies shows that many aspects, such as the fate of leached toxins, degradation of plant material, and distribution of crop residues in the aquatic habitat, are insufficiently investigated. Together with these research needs, we identify standardization of test methods as an issue of high priority, both for research and risk assessment needed for GMO regulation.

Whole-Life-Stage Characterization in the Basic Biology of Daphnia magna and Effects of TDCIPP on Growth, Reproduction, Survival, and Transcription of Genes

Toxicity tests of chemicals have mainly focused on the partial life-cycle evaluation of model animals. Limited information is available for the evaluation of effects of chemicals from a whole-life-stage exposure perspective. The objective of this study was to perform a whole-life-stage characterization in the basic biology of Daphnia magna (D. magna) and evaluate the effects of a known organophosphate ester (OPE) contaminant, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), on growth, reproduction, survival, and transcription of genes. The whole-life-stage characterization in growth, reproduction, and survival of D. magna was conducted, and representative sampling time points for the three developmental stages were identified (day 6, day 32, and day 62). Transcriptomic profiles for these three stages were compared, and stage-specific PCR arrays of D. magna were developed. The whole-life-stage exposure to environmentally relevant or greater concentrations of TDCIPP significantly inhibited growth and reproduction of D. magna and decreased survival at the later stage of the exposure experiment (≥32 days). Such adverse effects were not observed in the early stage of the exposure (<32 days), suggesting that short-term toxicity tests, such as the standard 21-day test, might underestimate the environmental risk of TDCIPP. Furthermore, expressions of genes selected at day 6, day 32, and day 62 were significantly changed after TDCIPP exposure, and the changes in the expressions of partial genes were correlated to the inhibitory effects on growth, reproduction, and survival.

Criticism of EFSA's scientific opinion on combinatorial effects of 'stacked' GM plants

Recent genetically modified plants tend to include both insect resistance and herbicide tolerance traits. Some of these 'stacked' GM plants have multiple Cry-toxins expressed as well as tolerance to several herbicides. This means that non-target organisms in the environment (biodiversity) will be co-exposed to multiple stressors simultaneously. A similar co-exposure may happen to consumers through chemical residues in the food chain. EFSA, the responsible unit for minimizing risk of harm in European food chains, has expressed its scientific interest in combinatorial effects. However, when new data showed how two Cry-toxins acted in combination (added toxicity), and that the same Cry-toxins showed combinatorial effects when co-exposed with Roundup (Bøhn et al., 2016), EFSA dismissed these new peer-reviewed results. In effect, EFSA claimed that combinatorial effects are not relevant for itself. EFSA was justifying this by referring to a policy question, and by making invalid assumptions, which could have been checked directly with the lead-author. With such approach, EFSA may miss the opportunity to improve its environmental and health risk assessment of toxins and pesticides in the food chain. Failure to follow its own published requests for combinatorial effects research, may also risk jeopardizing EFSA's scientific and public reputation.

The distinct properties of natural and GM cry insecticidal proteins

The Cry toxins are a family of crystal-forming proteins produced by the bacterium Bacillus thuringiensis. Their mode of action is thought to be to create pores that disrupt the gut epithelial membranes of juvenile insects. These pores allow pathogen entry into the hemocoel, thereby killing the insect. Genes encoding a spectrum of Cry toxins, including Cry mutants, Cry chimaeras and other Cry derivatives, are used commercially to enhance insect resistance in genetically modified (GM) crops. In most countries of the world, such GM crops are regulated and must be assessed for human and environmental safety. However, such risk assessments often do not test the GM crop or its tissues directly. Instead, assessments rely primarily on historical information from naturally occurring Cry proteins and on data collected on Cry proteins (called 'surrogates') purified from laboratory strains of bacteria engineered to express Cry protein. However, neither surrogates nor naturally occurring Cry proteins are identical to the proteins to which humans or other nontarget organisms are exposed by the production and consumption of GM plants. To-date there has been no systematic survey of these differences. This review fills this knowledge gap with respect to the most commonly grown GM Cry-containing crops approved for international use. Having described the specific differences between natural, surrogate and GM Cry proteins this review assesses these differences for their potential to undermine the reliability of risk assessments. Lastly, we make specific recommendations for improving risk assessments.

Annual post-market environmental monitoring (PMEM) report on the cultivation of genetically modified maize MON 810 in 2015 from Monsanto Europe S.A

Following a request from the European Commission, the Panel on Genetically Modified Organisms of the European Food Safety Authority (GMO Panel) assessed the annual post-market environmental monitoring (PMEM) report for the 2015 growing season of the Cry1Ab-expressing maize event MON 810 provided by Monsanto Europe S.A. The GMO Panel concludes that the insect resistance monitoring data submitted to EFSA do not indicate a decrease in susceptibility of field Iberian populations of corn borers to the Cry1Ab protein during the 2015 season. However, since the methodology for insect resistance monitoring remained unchanged compared to previous PMEM reports, the GMO Panel reiterates its previous recommendations on resistance monitoring to provide sufficient detection sensitivity. Although the farmer alert system to report complaints about product performance could complement the information obtained from the laboratory bioassays, the GMO Panel is currently not in a position to appraise its usefulness, and therefore encourages the consent holder to provide more information on this complementary resistance monitoring tool. The data on general surveillance (GS) do not indicate any unanticipated adverse effects on human and animal health or the environment arising from the cultivation of maize MON 810. The GMO Panel reiterates its previous recommendations on the analysis of farmer questionnaires, and advises the consent holder to provide more detailed information on the conducting and reporting of the literature search in future annual PMEM reports. Moreover, the GMO Panel encourages relevant parties to continue developing a methodological framework to use existing networks in the broader context of environmental monitoring. The GMO Panel concludes that the case-specific monitoring (CSM) and GS activities of maize MON 810 as carried out by the consent holder do not provide evidence that would invalidate previous GMO Panel evaluations on the safety of maize MON 810.

In plastico: laboratory material newness affects growth and reproduction of Daphnia magna reared in 50-ml polypropylene tubes

Plastic laboratory materials are found to affect vital parameters of the waterflea Daphnia magna. The main responsible factor is defined as “newness” of the materials. Juvenile D. magna were raised individually in; a) new laboratory-standard 50 ml polypropylene tubes, and; b) identical tubes which had been washed and aerated for several weeks. Newness had significant effects on growth and fecundity of D. magna. New tubes caused delayed maturation, reduced reproduction and reduced growth when compared to washed and re-used tubes of the same commercial brand. The findings indicate that newness of tubes has inhibiting or toxic effects on D. magna. Often laboratory plastics are intended for single-use due to sterility demands. Newness might be an important confounding factor in research results and should not be disregarded. Disposable plastic utensils may come with a seemingly ignored cost and induce adverse effects in biological test-organisms and systems. The presented findings accentuate continued need for general awareness concerning confounding factors stemming from material laboratory environment. Based on the present findings the authors suggest that plastics intended for use in sensitive research may need to be washed and aerated prior to use.

Ecotoxicological effects of larvicide used in the control of Aedes aegypti on nontarget organisms: Redefining the use of pyriproxyfen

The continued widespread use of larvicides in Aedes aegypti control programs is still a necessary strategy, since there are no apparent efficient vaccines against arboviruses. However, chemical approaches may affect nontarget organisms and produce detrimental effects to environmental health. Therefore, the aim of this study was to conduct toxicity testing for pyriproxyfen at different concentrations using Daphnia magna and Artemia salina as model organisms to evaluate the ecotoxicological parameters. This study describes the toxicological effects of pyriproxyfen on both microcrustaceans, which are widely used in bioassays because of their sensitivity to changes in hydrosphere. Data demonstrated that the calculated EC_50-48h value of pyriproxyfen was 2.5 μg/for D. magna and A. salina; the no-observed-effect concentration (NOEC) and the lowest-observed-effect concentration (LOEC) of pyriproxyfen were found to be 0.63 and 1.25 μg/L for Artemia salina and Daphnia magna, respectively. In chronic toxicity and reproduction tests on D. magna, a calculated CL_50-7day (lethality on 50% of daphnids after 7 days of chronic test) and an EC_50-21day (50% reduction in the reproductive output of parental daphnids after 21 days of exposure) higher than 1.25 μg/L pyriproxyfen were observed. The time of first reproduction was significantly increased in D. magna after exposure to environmentally relevant concentrations of pyriproxyfen, but other reproduction parameters were not markedly altered. Environmental risk assessment revealed that pyriproxyfen is highly toxic for both branchiopods. Data demonstrated that pyriproxyfen may produce adverse effects on the aquatic ecosystem at concentrations required to control Ae. aegypti.

Interactions between Bt crops and aquatic ecosystems: A review

The term Bt crops collectively refers to crops that have been genetically modified to include a gene (or genes) sourced from Bacillus thuringiensis (Bt) bacteria. These genes confer the ability to produce proteins toxic to certain insect pests. The interaction between Bt crops and adjacent aquatic ecosystems has received limited attention in research and risk assessment, despite the fact that some Bt crops have been in commercial use for 20 yr. Reports of effects on aquatic organisms such as Daphnia magna, Elliptio complanata, and Chironomus dilutus suggest that some aquatic species may be negatively affected, whereas other reports suggest that the decreased use of insecticides precipitated by Bt crops may benefit aquatic communities. The present study reviews the literature regarding entry routes and exposure pathways by which aquatic organisms may be exposed to Bt crop material, as well as feeding trials and field surveys that have investigated the effects of Bt-expressing plant material on such organisms. The present review also discusses how Bt crop development has moved past single-gene events, toward multigene stacked varieties that often contain herbicide resistance genes in addition to multiple Bt genes, and how their use (in conjunction with co-technology such as glyphosate/Roundup) may impact and interact with aquatic ecosystems. Lastly, suggestions for further research in this field are provided. Environ Toxicol Chem 2016;35:2891-2902. © 2016 SETAC.

Genetically modified rice Bt-Shanyou63 expressing Cry1Ab/c protein does not harm Daphnia magna

The genetically modified (GM) rice Bt-ShanYou63 (Bt-SY63) received an official biosafety certificate while its safety remained in dispute. In a lifelong study, Daphnia magna were experimentally fed a basal diet of rice flours from Bt-SY63 or its parental rice ShanYou63 (SY63) at concentrations of 0.2mg, 0.3mg, or 0.4mgC (per individual per day). Overall the survival, body size, and reproduction of the animals were comparable between Bt-SY63 and ShanYou63.. The results showed that no significant differences were observed in growth and reproduction parameters between D. magna fed GM and non-GM flour and no dose-related changes occurred in all the values. Based on the different parameters assessed, the GM rice Bt-SY63 is a safe food source for D. magna that does not differ in quality from non-GM rice.

Safety assessment of GM plants: An updated review of the scientific literature

In a wide revision of the literature conducted in 2000, I noted that the information in scientific journals on the safety of genetically modified (GM) foods in general, and GM plants in particular, was scarce. Of course, it was not sufficient to guarantee that the consumption of these products should not mean risks for the health of the consumers. Because of the scientific interest in GM organisms (GMOs), as well as the great concern that the consumption of GM foods/plants has raised in a number of countries, I conducted two subsequent revisions (2007 and 2011) on the adverse/toxic effects of GM plants. In the present review, I have updated the information on the potential adverse health effects of GM plants consumed as food and/or feed. With only a few exceptions, the reported studies in the last six years show rather similar conclusions; that is to say, the assessed GM soybeans, rice, corn/maize and wheat would be as safe as the parental species of these plants. However, in spite of the notable increase in the available information, studies on the long-term health effects of GM plants, including tests of mutagenicity, teratogenicity and carcinogenicity seem to be still clearly necessary.

Prioritizing stream types according to their potential risk to receive crop plant material--A GIS-based procedure to assist in the risk assessment of genetically modified crops and systemic insecticide residues

Crop plant residues may enter aquatic ecosystems via wind deposition or surface runoff. In the case of genetically modified crops or crops treated with systemic pesticides, these materials may contain insecticidal Bt toxins or pesticides that potentially affect aquatic life. However, the particular exposure pattern of aquatic ecosystems (i.e., via plant material) is not properly reflected in current risk assessment schemes, which primarily focus on waterborne toxicity and not on plant material as the route of uptake. To assist in risk assessment, the present study proposes a prioritization procedure of stream types based on the freshwater network and crop-specific cultivation data using maize in Germany as a model system. To identify stream types with a high probability of receiving crop materials, we developed a formalized, criteria-based and thus transparent procedure that considers the exposure-related parameters, ecological status--an estimate of the diversity and potential vulnerability of local communities towards anthropogenic stress--and availability of uncontaminated reference sections. By applying the procedure to maize, ten stream types out of 38 are expected to be the most relevant if the ecological effects from plant-incorporated pesticides need to be evaluated. This information is an important first step to identifying habitats within these stream types with a high probability of receiving crop plant material at a more local scale, including accumulation areas. Moreover, the prioritization procedure developed in the present study may support the selection of aquatic species for ecotoxicological testing based on their probability of occurrence in stream types having a higher chance of exposure. Finally, this procedure can be adapted to any geographical region or crop of interest and is, therefore, a valuable tool for a site-specific risk assessment of crop plants carrying systemic pesticides or novel proteins, such as insecticidal Bt toxins, expressed in genetically modified crops.