SciCombinator

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Concept: Genetically modified food

653

The landscape for genetically modified organisms is changing, thanks to sharp increases in the amounts and numbers of chemical herbicides applied to GM crops and the classification of two of the most commonly used herbicides as probably or possibly carcinogenic to humans.

Concepts: DNA, Gene expression, Health, Agriculture, Genetically modified organism, Genetically modified food, Genetically modified organisms, Golden rice

254

The role of genetically modified (GM) crops for food security is the subject of public controversy. GM crops could contribute to food production increases and higher food availability. There may also be impacts on food quality and nutrient composition. Finally, growing GM crops may influence farmers' income and thus their economic access to food. Smallholder farmers make up a large proportion of the undernourished people worldwide. Our study focuses on this latter aspect and provides the first ex post analysis of food security impacts of GM crops at the micro level. We use comprehensive panel data collected over several years from farm households in India, where insect-resistant GM cotton has been widely adopted. Controlling for other factors, the adoption of GM cotton has significantly improved calorie consumption and dietary quality, resulting from increased family incomes. This technology has reduced food insecurity by 15-20% among cotton-producing households. GM crops alone will not solve the hunger problem, but they can be an important component in a broader food security strategy.

Concepts: Agriculture, Food, Malnutrition, Food security, Household income in the United States, Famine, Genetically modified food, Food industry

189

Honey bee pollination is a key ecosystem service to nature and agriculture. However, biosafety research on genetically modified crops rarely considers effects on nurse bees from intact colonies, even though they receive and primarily process the largest amount of pollen. The objective of this study was to analyze the response of nurse bees and their gut bacteria to pollen from Bt maize expressing three different insecticidal Cry proteins (Cry1A.105, Cry2Ab2, and Cry3Bb1). Naturally Cry proteins are produced by bacteria (Bacillus thuringiensis). Colonies of Apis mellifera carnica were kept during anthesis in flight cages on field plots with the Bt maize, two different conventionally bred maize varieties, and without cages, 1-km outside of the experimental maize field to allow ad libitum foraging to mixed pollen sources. During their 10-days life span, the consumption of Bt maize pollen had no effect on their survival rate, body weight and rates of pollen digestion compared to the conventional maize varieties. As indicated by ELISA-quantification of Cry1A.105 and Cry3Bb1, more than 98% of the recombinant proteins were degraded. Bacterial population sizes in the gut were not affected by the genetic modification. Bt-maize, conventional varieties and mixed pollen sources selected for significantly different bacterial communities which were, however, composed of the same dominant members, including Proteobacteria in the midgut and Lactobacillus sp. and Bifidobacterium sp. in the hindgut. Surprisingly, Cry proteins from natural sources, most likely B. thuringiensis, were detected in bees with no exposure to Bt maize. The natural occurrence of Cry proteins and the lack of detectable effects on nurse bees and their gut bacteria give no indication for harmful effects of this Bt maize on nurse honey bees.

Concepts: DNA, Bacteria, Gut flora, Insect, Escherichia coli, Honey bee, Beekeeping, Genetically modified food

174

In this study, the applicability of droplet digital PCR (ddPCR) for routine analysis in food and feed samples was demonstrated with the quantification of genetically modified organisms (GMOs). Real-time quantitative polymerase chain reaction (qPCR) is currently used for quantitative molecular analysis of the presence of GMOs in products. However, its use is limited for detecting and quantifying very small numbers of DNA targets, as in some complex food and feed matrices. Using ddPCR duplex assay, we have measured the absolute numbers of MON810 transgene and hmg maize reference gene copies in DNA samples. Key performance parameters of the assay were determined. The ddPCR system is shown to offer precise absolute and relative quantification of targets, without the need for calibration curves. The sensitivity (five target DNA copies) of the ddPCR assay compares well with those of individual qPCR assays and of the chamber digital PCR (cdPCR) approach. It offers a dynamic range over four orders of magnitude, greater than that of cdPCR. Moreover, when compared to qPCR, the ddPCR assay showed better repeatability at low target concentrations and a greater tolerance to inhibitors. Finally, ddPCR throughput and cost are advantageous relative to those of qPCR for routine GMO quantification. It is thus concluded that ddPCR technology can be applied for routine quantification of GMOs, or any other domain where quantitative analysis of food and feed samples is needed.

Concepts: DNA, Gene expression, Polymerase chain reaction, Molecular biology, DNA replication, DNA polymerase, Genetically modified organism, Genetically modified food

170

Fully drought-resistant crop plants would be beneficial, but selection breeding has not produced them. Genetic modification of species by introduction of very many genes is claimed, predominantly, to have given drought resistance. This review analyses the physiological responses of genetically modified (GM) plants to water deficits, the mechanisms, and the consequences. The GM literature neglects physiology and is unspecific in definitions, which are considered here, together with methods of assessment and the type of drought resistance resulting. Experiments in soil with cessation of watering demonstrate drought resistance in GM plants as later stress development than in wild-type (WT) plants. This is caused by slower total water loss from the GM plants which have (or may have-morphology is often poorly defined) smaller total leaf area (LA) and/or decreased stomatal conductance (g(s)), associated with thicker laminae (denser mesophyll and smaller cells). Non-linear soil water characteristics result in extreme stress symptoms in WT before GM plants. Then, WT and GM plants are rewatered: faster and better recovery of GM plants is taken to show their greater drought resistance. Mechanisms targeted in genetic modification are then, incorrectly, considered responsible for the drought resistance. However, this is not valid as the initial conditions in WT and GM plants are not comparable. GM plants exhibit a form of ‘drought resistance’ for which the term ‘delayed stress onset’ is introduced. Claims that specific alterations to metabolism give drought resistance [for which the term ‘constitutive metabolic dehydration tolerance’ (CMDT) is suggested] are not critically demonstrated, and experimental tests are suggested. Small LA and g(s) may not decrease productivity in well-watered plants under laboratory conditions but may in the field. Optimization of GM traits to environment has not been analysed critically and is required in field trials, for example of recently released oilseed rape and maize which show ‘drought resistance’, probably due to delayed stress onset. Current evidence is that GM plants may not be better able to cope with drought than selection-bred cultivars.

Concepts: DNA, Gene, Water, Biotechnology, Francis Crick, James D. Watson, Genetically modified food, Genetic engineering

167

There is great uncertainty due to challenges of escalating population growth and climate change. Public perception that diverges from the scientific community may decrease the effectiveness of scientific inquiry and innovation as tools to solve these challenges. The objective of this study was to identify the factors associated with the divergence of public opinion from scientific consensus regarding the safety of genetically modified (GM) foods and human involvement in global warming (GW). Results indicate that the effects of knowledge on public opinion are complex and non-uniform across types of knowledge (i.e., perceived and actual) or issues. Political affiliation affects agreement with science; Democrats were more likely to agree that GM food is safe and human actions cause GW. Respondents who had relatively higher cognitive function or held illusionary correlations about GM food or GW were more likely to have an opinion that differed from the scientific community.

Concepts: Scientific method, Psychology, Cognition, Science, Perception, Mind, Global warming, Genetically modified food

163

Since their first commercialization, the diversity of taxa and the genetic composition of transgene sequences in genetically modified plants (GMOs) are constantly increasing. To date, the detection of GMOs and derived products is commonly performed by PCR-based methods targeting specific DNA sequences introduced into the host genome. Information available regarding the GMOs' molecular characterization is dispersed and not appropriately organized. For this reason, GMO testing is very challenging and requires more complex screening strategies and decision making schemes, demanding in return the use of efficient bioinformatics tools relying on reliable information.DescriptionThe GMOseek matrix was built as a comprehensive, online open-access tabulated database which provides a reliable, comprehensive and user-friendly overview of 328 GMO events and 247 different genetic elements (status: 18/07/2013). The GMOseek matrix is aiming to facilitate GMO detection from plant origin at different phases of the analysis. It assists in selecting the targets for a screening analysis, interpreting the screening results, checking the occurrence of a screening element in a group of selected GMOs, identifying gaps in the available pool of GMO detection methods, and designing a decision tree. The GMOseek matrix is an independent database with effective functionalities in a format facilitating transferability to other platforms. Data were collected from all available sources and experimentally tested where detection methods and certified reference materials (CRMs) were available.

Concepts: DNA, Genetics, Gene expression, Molecular biology, Horizontal gene transfer, Decision theory, Genetically modified organism, Genetically modified food

159

Multiple lines of transgenic rice expressing insecticidal genes from the bacterium Bacillus thuringiensis (Bt) have been developed in China, posing the prospect of increases in production with decreased application of pesticides. We explore the issues facing adoption of Bt rice for commercial production in China. A body of safety assessment work on Bt rice has shown that Bt rice poses a negligible risk to the environment and that Bt rice products are as safe as non-Bt control rice products as food. China has a relatively well-developed regulatory system for risk assessment and management of genetically modified (GM) plants; however, decision-making regarding approval of commercial production has become politicized, and two Bt rice lines that otherwise were ready have not been allowed to enter the Chinese agricultural system. We predict that Chinese farmers would value the prospect of increased yield with decreased use of pesticide and would readily adopt production of Bt rice. That Bt rice lines may not be commercialized in the near future we attribute to social pressures, largely due to the low level of understanding and acceptance of GM crops by Chinese consumers. Hence, enhancing communication of GM crop science-related issues to the public is an important, unmet need. While the dynamics of each issue are particular to China, they typify those in many countries where adoption of GM crops has been not been rapid; hence, the assessment of these dynamics might inform resolution of these issues in other countries.

Concepts: Bacteria, Risk, Pesticide, Bacillus thuringiensis, Genetically modified organism, Genetically modified food, Genetic engineering, Monsanto

150

Transgenic crop “pyramids” producing two or more Bacillus thuringiensis (Bt) toxins active against the same pest are used to delay evolution of resistance in insect pest populations. Laboratory and greenhouse experiments were performed with fall armyworm, Spodoptera frugiperda, to characterize resistance to Bt maize producing Cry1A.105 and Cry2Ab and test some assumptions of the “pyramid” resistance management strategy. Selection of a field-derived strain of S. frugiperda already resistant to Cry1F maize with Cry1A.105 + Cry2Ab maize for ten generations produced resistance that allowed the larvae to colonize and complete the life cycle on these Bt maize plants. Greenhouse experiments revealed that the resistance was completely recessive (Dx = 0), incomplete, autosomal, and without maternal effects or cross-resistance to the Vip3Aa20 toxin produced in other Bt maize events. This profile of resistance supports some of the assumptions of the pyramid strategy for resistance management. However, laboratory experiments with purified Bt toxin and plant leaf tissue showed that resistance to Cry1A.105 + Cry2Ab2 maize further increased resistance to Cry1Fa, which indicates that populations of fall armyworm have high potential for developing resistance to some currently available pyramided maize used against this pest, especially where resistance to Cry1Fa was reported in the field.

Concepts: Bacillus, Leaf, Bacillus thuringiensis, Endotoxin, Genetically modified food, Army worm, Spodoptera, Transgenic maize

122

Despite the rapid adoption of genetically modified (GM) crops by farmers in many countries, controversies about this technology continue. Uncertainty about GM crop impacts is one reason for widespread public suspicion.

Concepts: Agriculture, Genetically modified organism, Crops, Genetically modified food, Genetic engineering, Crop