MS-based analytical methodologies to characterize genetically modified crops

Mass Spectrometry as a Crucial Analytical Basis for Omics Sciences

This review is devoted to the consideration of mass spectrometric platforms as applied to omics sciences. The most significant attention is paid to omics related to life sciences (genomics, proteomics, meta-bolomics, lipidomics, glycomics, plantomics, etc.). Mass spectrometric approaches to solving the problems of petroleomics, polymeromics, foodomics, humeomics, and exosomics, related to inorganic sciences, are also discussed. The review comparatively presents the advantages of various principles of separation and mass spectral techniques, complementary derivatization, used to obtain large arrays of various structural and quantitative information in the mentioned omics sciences.

Untargeted Proteomics-Based Approach to Investigate Unintended Changes in Genetically Modified Maize for Environmental Risk Assessment Purpose

Profiling technologies, such as proteomics, allow the simultaneous measurement and comparison of thousands of plant components without prior knowledge of their identity. The combination of these non-targeted methods facilitates a more comprehensive approach than targeted methods and thus provides additional opportunities to identify genotypic changes resulting from genetic modification, including new allergens or toxins. The purpose of this study was to investigate unintended changes in GM Bt maize grown in South Africa. In the present study, we used bi-dimensional gel electrophoresis based on fluorescence staining, coupled with mass spectrometry in order to compare the proteome of the field-grown transgenic hybrid (MON810) and its near-isogenic counterpart. Proteomic data showed that energy metabolism and redox homeostasis were unequally modulated in GM Bt and non-GM maize variety samples. In addition, a potential allergenic protein—pathogenesis related protein −1 has been identified in our sample set. Our data shows that the GM variety is not substantially equivalent to its non-transgenic near-isogenic variety and further studies should be conducted in order to address the biological relevance and the potential risks of such changes. These finding highlight the suitability of unbiased profiling approaches to complement current GMO risk assessment practices worldwide.

Screening of Processed Foods for Transgenic Proteins from Genetically Engineered Plants Using Targeted Mass Spectrometry

Screening of food products for the presence of material from genetically engineered (GE) plants is typically done using deoxyribonucleic acid (DNA)-based methods to detect the presence of transgenic DNA. In this study, we have demonstrated the feasibility of using targeted mass spectrometry (MS) to detect a protein expressed by transgenic DNA to confirm the presence of GE plant material in processed foods. Scheduled parallel reaction monitoring (sPRM) was used to detect the enzyme, 5-enolpyruvulshikimate-3-phosphate synthase, from Agrobacterium sp. strain CP4 (CP4 EPSPS), which confers glyphosate tolerance in transgenic crops. Five CP4 EPSPS surrogate peptides and their corresponding retention times identified via data-dependent LC/MS/MS analysis of a glyphosate-tolerant soybean certified reference material, GTS 40-3-2, were used to develop the sPRM assay. The assay was used to screen four soy-based infant formulas, four corn-based cereals, corn tortilla chips, and cornmeal for the presence of CP4 EPSPS. At least four of the five selected surrogate peptides were detected in nine of the products analyzed, suggesting that targeted MS can serve as a complementary analytical method to DNA-based methods for the detection of material from GE plants in processed foods.

Mass spectrometry combined with affinity probes for the identification of CP4 EPSPS in genetically modified soybeans

Sample preparation methods used for genetically modified organisms (GMOs) analysis are often time consuming, require extensive manual manipulation, and result in limited amounts of purified protein, which may complicate the detection of low-abundance GM protein. A robust sample pretreatment method prior to mass spectrometry (MS) detection of the transgenic protein (5-enolpyruvylshikimate-3-phosphate synthase [CP4 EPSPS]) present in Roundup Ready soya is investigated. Liquid chromatography-multiple reaction monitoring tandem MS (nano LC-MS/MS-MRM) was used for the detection and quantification of CP4 EPSPS. Gold nanoparticles (AuNPs) and concanavalin A (Con A)-immobilized Sepharose 4B were used as selective probes for the separation of the major storage proteins in soybeans. AuNPs that enable the capture of cysteine-containing proteins were used to reduce the complexity of the crude extract of GM soya. Con A-sepharose was used for the affinity capture of β-conglycinin and other glycoproteins of soya prior to enzymatic digestion. The methods enabled the detection of unique peptides of CP4 EPSPS at a level as low as 0.5% of GM soya in MRM mode. Stable-isotope dimethyl labeling was further applied to the quantification of GM soya. Both probes exhibited high selectivity and efficiency for the affinity capture of storage proteins, leading to the quantitative detection at 0.5% GM soya, which is a level below the current European Union's threshold for food labeling. The square correlation coefficients were greater than 0.99. The approach for sample preparation is very simple without the need for time-consuming protein prefractionation or separation procedures and thus presents a significant improvement over existing methods for the analysis of the GM soya protein.

Problem formulation and phenotypic characterisation for the development of novel crops

Phenotypic characterisation provides important information about novel crops that helps their developers to make technical and commercial decisions. Phenotypic characterisation comprises two activities. Product characterisation checks that the novel crop has the qualities of a viable product-the intended traits have been introduced and work as expected, and no unintended changes have been made that will adversely affect the performance of the final product. Risk assessment evaluates whether the intended and unintended changes are likely to harm human health or the environment. Product characterisation follows the principles of problem formulation, namely that the characteristics required in the final product are defined and criteria to decide whether the novel crop will have these properties are set. The hypothesis that the novel crop meets the criteria are tested during product development. If the hypothesis is corroborated, development continues, and if the hypothesis is falsified, the product is redesigned or its development is halted. Risk assessment should follow the same principles. Criteria that indicate the crop poses unacceptable risk should be set, and the hypothesis that the crop does not possess those properties should be tested. However, risk assessment, particularly when considering unintended changes introduced by new plant breeding methods such as gene editing, often ignores these principles. Instead, phenotypic characterisation seeks to catalogue all unintended changes by profiling methods and then proceeds to work out whether any of the changes are important. This paper argues that profiling is an inefficient and ineffective method of phenotypic characterisation for risk assessment. It discusses reasons why profiling is favoured and corrects some misconceptions about problem formulation.

Transgenic Plant Detection Using an AuNPs Based SPR Biosensor

The intensive development and commercialization of genetically modified plants observed over the last decade has led to the development of transgenic detection methods that are rapid and sensitive. Among the strategies used for the detection/monitoring of genetically modified organisms (GMOs), surface plasmon resonance (SPR) meets the necessary criteria. This optical technique measures the changes in the refractive index in the vicinity of thin metal layers (i.e., gold) in response to biomolecular interactions occurring at a flat metal‒solution interface. Additionally, it allows the application of functionalized gold nanoparticles (AuNPs) in SPR research to enhance the signal intensity. In the present study, an SPR method, enhanced by the application of AuNPs, was developed to detect transgenic tobacco plants carrying a Streptococcus mutans antigen. The basis for the detection of the target DNA was the hybridization between the genomic DNA isolated from the leaves, stems, and roots of the transgenic tobacco and the biotinylated oligonucleotide probes immobilized onto a streptavidin (SA) sensor chip. SA-functionalized AuNPs coated with a second type of biotinylated probe were applied to increase the sensitivity of the detection method. Analysis of the results indicated that the constructed SPR-based sensor chip can potentially recognize complementary standard fragments (nonamplified genomic DNA) at concentrations as low as 1 pM. Thus, nonamplified transgenic DNA was detected using a label-free and real-time AuNPs-enhanced SPR biosensing method. This unique approach could be used to detect GMOs with high efficiency, even at a low detection limit, high repeatability, and with less time and a lower cost needed for each analysis.

Using problem formulation to clarify the meaning of weight of evidence and biological relevance in environmental risk assessments for genetically modified crops

Weight of evidence and biological relevance are important concepts for risk assessment and decision-making over the use of GM crops; however, their meanings are not well defined. We use problem formulation to clarify the definition of these concepts and thereby identify data that are relevant for risk assessment. Problem formulation defines criteria for the acceptability of risk and devises rigorous tests of the hypothesis that the criteria are met. Corroboration or falsification of such hypotheses characterize risk and enable predictable and transparent decisions about whether certain risks from using a particular GM crop are acceptable. Decisions based on a weight of evidence approach use a synthesis of several lines of evidence, whereas a "definitive" approach to risk assessment enables some decisions to be based on the results of a single test. Data are biologically relevant for risk assessment only if they test a hypothesis that is useful for decision-making.

Molecular Analysis for Characterizing Transgenic Events

To develop a commercial trait product, a large number of transgenic events are often produced to obtain the event with desired level of expression. It is crucial to develop efficient and sensitive molecular characterization methods to advance events with stable transgene expression, free of vector backbone sequences and without major changes to the native genome caused by transgene insertion. Here, we discuss a variety of analytical tools, including quantitative PCR (qPCR), Southern blot analysis, and various sequencing technologies, which have been widely used to determine the insert copy number, presence/absence of vector backbone sequences, integrity of the T-DNA, and genomic location of the T-DNA insertion. Moreover, since the discovery of RNA interference in 1998 (Fire et al., Nature 391:806-811, 1998), RNAi has emerged as another powerful tool in in the development of a new transgenic trait for insect control. RNAi creates a double-stranded RNA duplex as the active molecule which forms a strong secondary structure, resulting in challenges for detection. In addition to molecular analysis at the DNA level, this chapter describes detection methods of the active molecules (i.e., double-stranded RNA) for RNAi-based traits.

Foodomics and Food Safety: Where We Are

The power of foodomics as a discipline that is now broadly used for quality assurance of food products and adulteration identification, as well as for determining the safety of food, is presented. Concerning sample preparation and application, maintenance of highly sophisticated instruments for both high-performance and high-throughput techniques, and analysis and data interpretation, special attention has to be paid to the development of skilled analysts. The obtained data shall be integrated under a strong bioinformatics environment. Modern mass spectrometry is an extremely powerful analytical tool since it can provide direct qualitative and quantitative information about a molecule of interest from only a minute amount of sample. Quality of this information is influenced by the sample preparation procedure, the type of mass spectrometer used and the analyst's skills. Technical advances are bringing new instruments of increased sensitivity, resolution and speed to the market. Other methods presented here give additional information and can be used as complementary tools to mass spectrometry or for validation of obtained results. Genomics and transcriptomics, as well as affinity-based methods, still have a broad use in food analysis. Serious drawbacks of some of them, especially the affinity-based methods, are the cross-reactivity between similar molecules and the influence of complex food matrices. However, these techniques can be used for pre-screening in order to reduce the large number of samples. Great progress has been made in the application of bioinformatics in foodomics. These developments enabled processing of large amounts of generated data for both identification and quantification, and for corresponding modeling.

Exposure of livestock to GM feeds: Detectability and measurement

This review explores the possibilities to determine livestock consumption of genetically modified (GM) feeds/ingredients including detection of genetically modified organism (GMO)-related DNA or proteins in animal samples, and the documentary system that is in place for GM feeds under EU legislation. The presence and level of GMO-related DNA and proteins can generally be readily measured in feeds, using established analytical methods such as polymerase chain reaction and immuno-assays, respectively. Various technical challenges remain, such as the simultaneous detection of multiple GMOs and the identification of unauthorized GMOs for which incomplete data on the inserted DNA may exist. Given that transfer of specific GMO-related DNA or protein from consumed feed to the animal had seldom been observed, this cannot serve as an indicator of the individual animal's prior exposure to GM feeds. To explore whether common practices, information exchange and the specific GM feed traceability system in the EU would allow to record GM feed consumption, the dairy chain in Catalonia, where GM maize is widely grown, was taken as an example. It was thus found that this system would neither enable determination of an animal's consumption of specific GM crops, nor would it allow for quantitation of the exposure.

Use of Foodomics for Control of Food Processing and Assessing of Food Safety

Food chain, food safety, and food-processing sectors face new challenges due to globalization of food chain and changes in the modern consumer preferences. In addition, gradually increasing microbial resistance, changes in climate, and human errors in food handling remain a pending barrier for the efficient global food safety management. Consequently, a need for development, validation, and implementation of rapid, sensitive, and accurate methods for assessment of food safety often termed as foodomics methods is required. Even though, the growing role of these high-throughput foodomic methods based on genomic, transcriptomic, proteomic, and metabolomic techniques has yet to be completely acknowledged by the regulatory agencies and bodies. The sensitivity and accuracy of these methods are superior to previously used standard analytical procedures and new methods are suitable to address a number of novel requirements posed by the food production sector and global food market.

An integrated multi-omics analysis of the NK603 Roundup-tolerant GM maize reveals metabolism disturbances caused by the transformation process

Glyphosate tolerant genetically modified (GM) maize NK603 was assessed as 'substantially equivalent' to its isogenic counterpart by a nutrient composition analysis in order to be granted market approval. We have applied contemporary in depth molecular profiling methods of NK603 maize kernels (sprayed or unsprayed with Roundup) and the isogenic corn to reassess its substantial equivalence status. Proteome profiles of the maize kernels revealed alterations in the levels of enzymes of glycolysis and TCA cycle pathways, which were reflective of an imbalance in energy metabolism. Changes in proteins and metabolites of glutathione metabolism were indicative of increased oxidative stress. The most pronounced metabolome differences between NK603 and its isogenic counterpart consisted of an increase in polyamines including N-acetyl-cadaverine (2.9-fold), N-acetylputrescine (1.8-fold), putrescine (2.7-fold) and cadaverine (28-fold), which depending on context can be either protective or a cause of toxicity. Our molecular profiling results show that NK603 and its isogenic control are not substantially equivalent.

Biomanufacturing of protective antibodies and other therapeutics in edible plant tissues for oral applications

Although plant expression systems used for production of therapeutic proteins have the advantage of being scalable at a low price, the downstream processing necessary to obtain pure therapeutic molecules is as expensive as for the traditional Chinese hamster ovary (CHO) platforms. However, when edible plant tissues (EPTs) are used, there is no need for exhaustive purification, because they can be delivered orally as partially purified formulations that are safe for consumption. This economic benefit is especially interesting when high doses of recombinant proteins are required throughout the treatment/prophylaxis period, as is the case for antibodies used for oral passive immunization (OPI). The secretory IgA (SIgA) antibodies, which are highly abundant in the digestive tract and mucosal secretions, and thus the first choice for OPI, have only been successfully produced in plant expression systems. Here, we cover most of the up-to-date examples of EPT-produced pharmaceuticals, including two examples of SIgA aimed at oral delivery. We describe the benefits and drawbacks of delivering partially purified formulations and discuss a number of practical considerations and criteria to take into account when using plant expression systems, such as subcellular targeting, protein degradation, glycosylation patterns and downstream strategies, all crucial for improved yield, high quality and low cost of the final product.

Review on proteomics for food authentication

Consumers have the right to know what is in the food they are eating. Accordingly, European and global food regulations require that the provenance of the food can be guaranteed from farm to fork. Many different instrumental techniques have been proposed for food authentication. Although traditional methods are still being used, new approaches such as genomics, proteomics, and metabolomics are helping to complement existing methodologies for verifying the claims made about certain food products. During the last decade, proteomics (the large-scale analysis of proteins in a particular biological system at a particular time) has been applied to different research areas within food technology. Since proteins can be used as markers for many properties of a food, even indicating processes to which the food has been subjected, they can provide further evidence of the foods labeling claim. This review is a comprehensive and updated overview of the applications, drawbacks, advantages, and challenges of proteomics for food authentication in the assessment of the foods compliance with labeling regulations and policies.

SIGNIFICANCE

This review paper provides a comprehensive and critical overview of the application of proteomics approaches to determine the authenticity of several food products updating the performances and current limitations of the applied techniques in both laboratory and industrial environments.

Comparative nutritional compositions and proteomics analysis of transgenic Xa21 rice seeds compared to conventional rice

Transgenic rice expressing the Xa21 gene have enhanced resistant to most devastating bacterial blight diseases caused by Xanthomonas oryzae pv. oryzae (Xoo). However, identification of unintended modifications, owing to the genetic modification, is an important aspect of transgenic crop safety assessment. In this study, the nutritional compositions of seeds from transgenic rice plants expressing the Xa21 gene were compared against non-transgenic rice seeds. In addition, to detect any changes in protein translation levels as a result of Xa21 gene expression, rice seed proteome analyses were also performed by two-dimensional gel electrophoresis. No significant differences were found in the nutritional compositions (proximate components, amino acids, minerals, vitamins and anti-nutrients) of the transgenic and non-transgenic rice seeds. Although gel electrophoresis identified 11 proteins that were differentially expressed between the transgenic and non-transgenic seed, only one of these (with a 20-fold up-regulation in the transgenic seed) shows nutrient reservoir activity. No new toxins or allergens were detected in the transgenic seeds.

Metabolic changes in transgenic maize mature seeds over-expressing the Aspergillus niger phyA2

Non-targeted metabolomics analysis revealed only intended metabolic changes in transgenic maize over-expressing the Aspergillus niger phyA2. Genetically modified (GM) crops account for a large proportion of modern agriculture worldwide, raising increasingly the public concerns of safety. Generally, according to substantial equivalence principle, if a GM crop is demonstrated to be equivalently safe to its conventional species, it is supposed to be safe. In this study, taking the advantage of an established non-target metabolomic profiling platform based on the combination of UPLC-MS/MS with GC-MS, we compared the mature seed metabolic changes in transgenic maize over-expressing the Aspergillus niger phyA2 with its non-transgenic counterpart and other 14 conventional maize lines. In total, levels of nine out of identified 210 metabolites were significantly changed in transgenic maize as compared with its non-transgenic counterpart, and the number of significantly altered metabolites was reduced to only four when the natural variations were taken into consideration. Notably, those four metabolites were all associated with targeted engineering pathway. Our results indicated that although both intended and non-intended metabolic changes occurred in the mature seeds of this GM maize event, only intended metabolic pathway was found to be out of the range of the natural metabolic variation in the metabolome of the transgenic maize. Therefore, only when natural metabolic variation was taken into account, could non-targeted metabolomics provide reliable objective compositional substantial equivalence analysis on GM crops.

Capillary Electrophoresis in Metabolomics

Metabolomics is an analytical toolbox to describe (all) low-molecular-weight compounds in a biological system, as cells, tissues, urine, and feces, as well as in serum and plasma. To analyze such complex biological samples, high requirements on the analytical technique are needed due to the high variation in compound physico-chemistry (cholesterol derivatives, amino acids, fatty acids as SCFA, MCFA, or LCFA, or pathway-related metabolites belonging to each individual organism) and concentration dynamic range. All main separation techniques (LC-MS, GC-MS) are applied in routine to metabolomics hyphenated or not to mass spectrometry, and capillary electrophoresis is a powerful high-resolving technique but still underused in this field of complex samples. Metabolomics can be performed in the non-targeted way to gain an overview on metabolite profiles in biological samples. Targeted metabolomics is applied to analyze quantitatively pre-selected metabolites. This chapter reviews the use of capillary electrophoresis in the field of metabolomics and exemplifies solutions in metabolite profiling and analysis in urine and plasma.

A proteomic analysis of seeds from Bt-transgenic Brassica napus and hybrids with wild B. juncea

Transgene insertions might have unintended side effects on the transgenic host, both crop and hybrids with wild relatives that harbor transgenes. We employed proteomic approaches to assess protein abundance changes in seeds from Bt-transgenic oilseed rape (Brassica napus) and its hybrids with wild mustard (B. juncea). A total of 24, 15 and 34 protein spots matching to 23, 13 and 31 unique genes were identified that changed at least 1.5 fold (p < 0.05, Student’s t-test) in abundance between transgenic (tBN) and non-transgenic (BN) oilseed rape, between hybrids of B. juncea (BJ) × tBN (BJtBN) and BJ × BN (BJBN) and between BJBN and BJ, respectively. Eight proteins had higher abundance in tBN than in BN. None of these proteins was toxic or nutritionally harmful to human health, which is not surprising since the seeds are not known to produce toxic proteins. Protein spots varying in abundance between BJtBN and BJBN seeds were the same or homologous to those in the respective parents. None of the differentially-accumulated proteins between BJtBN and BJBN were identical to those between tBN and BN. Results indicated that unintended effects resulted from transgene flow fell within the range of natural variability of hybridization and those found in the native host proteomes.

Current and new approaches in GMO detection: challenges and solutions

In many countries, genetically modified organisms (GMO) legislations have been established in order to guarantee the traceability of food/feed products on the market and to protect the consumer freedom of choice. Therefore, several GMO detection strategies, mainly based on DNA, have been developed to implement these legislations. Due to its numerous advantages, the quantitative PCR (qPCR) is the method of choice for the enforcement laboratories in GMO routine analysis. However, given the increasing number and diversity of GMO developed and put on the market around the world, some technical hurdles could be encountered with the qPCR technology, mainly owing to its inherent properties. To address these challenges, alternative GMO detection methods have been developed, allowing faster detections of single GM target (e.g., loop-mediated isothermal amplification), simultaneous detections of multiple GM targets (e.g., PCR capillary gel electrophoresis, microarray, and Luminex), more accurate quantification of GM targets (e.g., digital PCR), or characterization of partially known (e.g., DNA walking and Next Generation Sequencing (NGS)) or unknown (e.g., NGS) GMO. The benefits and drawbacks of these methods are discussed in this review.

Characterization and study of transgenic cultivars by capillary and microchip electrophoresis

Advances in biotechnology have increased the demand for suitable analytical techniques for the analysis of genetically modified organisms. Study of the substantial equivalence, discrimination between transgenic and non-transgenic cultivars, study of the unintended effects caused by a genetic modification or their response to diverse situations or stress conditions (e.g., environmental, climatic, infections) are some of the concerns that need to be addressed. Capillary electrophoresis (CE) is emerging as an alternative to conventional techniques for the study and characterization of genetically modified organisms. This article reviews the most recent applications of CE for the analysis and characterization of transgenic cultivars in the last five years. Different strategies have been described depending on the level analyzed (DNA, proteins or metabolites). Capillary gel electrophoresis (CGE) has shown to be particularly useful for the analysis of DNA fragments amplified by PCR. Metabolites and proteins have been mainly separated using capillary zone electrophoresis (CZE) using UV and MS detection. Electrophoretic chips have also proven their ability in the analysis of transgenic cultivars and a section describing the new applications is also included.

Metabolomics of genetically modified crops

Metabolomic-based approaches are increasingly applied to analyse genetically modified organisms (GMOs) making it possible to obtain broader and deeper information on the composition of GMOs compared to that obtained from traditional analytical approaches. The combination in metabolomics of advanced analytical methods and bioinformatics tools provides wide chemical compositional data that contributes to corroborate (or not) the substantial equivalence and occurrence of unintended changes resulting from genetic transformation. This review provides insight into recent progress in metabolomics studies on transgenic crops focusing mainly in papers published in the last decade.

Quantification of genetically modified soya using strong anion exchange chromatography and time-of-flight mass spectrometry

Stable-isotope dimethyl labeling was applied to the quantification of genetically modified (GM) soya. The herbicide-resistant gene-related protein 5-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) was labeled using a dimethyl labeling reagent, formaldehyde-H2 or -D2. The identification and quantification of CP4 EPSPS was performed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The CP4 EPSPS protein was separated from high abundance proteins using strong anion exchange chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Then, the tryptic peptides from the samples and reference were labeled with formaldehyde-H2 and formaldehyde-D2, respectively. The two labeled pools were mixed and analyzed using MALDI-MS. The data showed a good correlation between the peak ratio of the H- and D-labeled peptides and the GM soya percentages at 0.5, 1, 3, and 5 %, with R (2) of 0.99. The labeling reagents are readily available. The labeling experiments and the detection procedures are simple. The approach is useful for the quantification of GM soya at a level as low as 0.5 %.

Mass spectrometry in food proteomics: a tutorial

In the last decades, the continuous and rapid evolution of proteomic approaches has provided an efficient platform for the characterization of food-derived proteins. Particularly, the impressive increasing in performance and versatility of the MS instrumentation has contributed to the development of new analytical strategies for proteins, evidencing how MS arguably represents an indispensable tool in food proteomics. Investigation of protein composition in foodstuffs is helpful for understanding the relationship between the protein content and the nutritional and technological properties of foods, the production of methods for food traceability, the assessment of food quality and safety, including the detection of allergens and microbial contaminants in foods, or even the characterization of genetically modified products. Given the high variety of the food-derived proteins and considering their differences in chemical and physical properties, a single proteomic strategy for all purposes does not exist. Rather, proteomic approaches need to be adapted to each analytical problem, and development of new strategies is necessary in order to obtain always the best results. In this tutorial, the most relevant aspects of MS-based methodologies in food proteomics will be examined, and their advantages and drawbacks will be discussed.

Evaluation of unintended effects in the composition of tomatoes expressing a human immunoglobulin A against rotavirus

The production of neutralizing immunoglobulin A (IgA) in edible fruits as a means of oral passive immunization is a promising strategy for the inexpensive treatment of mucosal diseases. This approach is based on the assumption that the edible status remains unaltered in the immunoglobulin-expressing fruit, and therefore extensive purification is not required for mucosal delivery. However, unintended effects associated with IgA expression such as toxic secondary metabolites and protein allergens cannot be dismissed a priori and need to be investigated. This paper describes a collection of independent transgenic tomato lines expressing a neutralizing human IgA against rotavirus, a mucosal pathogen producing severe diarrhea episodes. This collection was used to evaluate possible unintended effects associated with recombinant IgA expression. A comparative analysis of protein and secondary metabolite profiles using wild type lines and other commercial varieties failed to find unsafe features significantly associated with IgA expression. Preliminary, the data indicate that formulations derived from IgA tomatoes are as safe for consumption as equivalent formulations derived from wild type tomatoes.

Availability and utility of crop composition data

The safety assessment of genetically modified (GM) crops is mandatory in many countries. Although the most important factor to take into account in these safety assessments is the primary effects of artificially introduced transgene-derived traits, possible unintended effects attributed to the insertion of transgenes must be carefully examined in parallel. However, foods are complex mixtures of compounds characterized by wide variations in composition and nutritional values. Food components are significantly affected by various factors such as cultivars and the cultivation environment including storage conditions after harvest, and it can thus be very difficult to detect potential adverse effects caused by the introduction of a transgene. A comparative approach focusing on the identification of differences between GM foods and their conventional counterparts has been performed to reveal potential safety issues and is considered the most appropriate strategy for the safety assessment of GM foods. This concept is widely shared by authorities in many countries. For the efficient safety assessment of GM crops, an easily accessible and wide-ranging compilation of crop composition data is required for use by researchers and regulatory agencies. Thus, we developed an Internet-accessible food composition database comprising key nutrients, antinutrients, endogenous toxicants, and physiologically active substances of staple crops such as rice and soybeans. The International Life Sciences Institute has also been addressing the same matter and has provided the public a crop composition database of soybeans, maize, and cotton.

A decade of plant proteomics and mass spectrometry: translation of technical advancements to food security and safety issues

Tremendous progress in plant proteomics driven by mass spectrometry (MS) techniques has been made since 2000 when few proteomics reports were published and plant proteomics was in its infancy. These achievements include the refinement of existing techniques and the search for new techniques to address food security, safety, and health issues. It is projected that in 2050, the world's population will reach 9-12 billion people demanding a food production increase of 34-70% (FAO, 2009) from today's food production. Provision of food in a sustainable and environmentally committed manner for such a demand without threatening natural resources, requires that agricultural production increases significantly and that postharvest handling and food manufacturing systems become more efficient requiring lower energy expenditure, a decrease in postharvest losses, less waste generation and food with longer shelf life. There is also a need to look for alternative protein sources to animal based (i.e., plant based) to be able to fulfill the increase in protein demands by 2050. Thus, plant biology has a critical role to play as a science capable of addressing such challenges. In this review, we discuss proteomics especially MS, as a platform, being utilized in plant biology research for the past 10 years having the potential to expedite the process of understanding plant biology for human benefits. The increasing application of proteomics technologies in food security, analysis, and safety is emphasized in this review. But, we are aware that no unique approach/technology is capable to address the global food issues. Proteomics-generated information/resources must be integrated and correlated with other omics-based approaches, information, and conventional programs to ensure sufficient food and resources for human development now and in the future.

Foodomics: a new comprehensive approach to food and nutrition

In the past 20 years, the scientific community has faced a great development in different fields due to the development of high-throughput, omics technologies. Starting from the four major types of omics measurements (genomics, transcriptomics, proteomics, and metabolomics), a variety of omics subdisciplines (epigenomics, lipidomics, interactomics, metallomics, diseasomics, etc.) has emerged. Thanks to the omics approach, researchers are now facing the possibility of connecting food components, foods, the diet, the individual, the health, and the diseases, but this broad vision needs not only the application of advanced technologies, but mainly the ability of looking at the problem with a different approach, a "foodomics approach". Foodomics is the comprehensive, high-throughput approach for the exploitation of food science in the light of an improvement of human nutrition. Foodomics is a new approach to food and nutrition that studies the food domain as a whole with the nutrition domain to reach the main objective, the optimization of human health and well-being.

Proteomic evaluation of genetically modified crops: current status and challenges

Hectares of genetically modified (GM) crops have increased exponentially since 1996, when such crops began to be commercialized. GM biotechnology, together with conventional breeding, has become the main approach to improving agronomic traits of crops. However, people are concerned about the safety of GM crops, especially GM-derived food and feed. Many efforts have been made to evaluate the unintended effects caused by the introduction of exogenous genes. "Omics" techniques have advantages over targeted analysis in evaluating such crops because of their use of high-throughput screening. Proteins are key players in gene function and are directly involved in metabolism and cellular development or have roles as toxins, antinutrients, or allergens, which are essential for human health. Thus, proteomics can be expected to become one of the most useful tools in safety assessment. This review assesses the potential of proteomics in evaluating various GM crops. We further describe the challenges in ensuring homogeneity and sensitivity in detection techniques.

Food Analysis: Present, Future, and Foodomics

This paper presents a revision on the instrumental analytical techniques and methods used in food analysis together with their main applications in food science research. The present paper includes a brief historical perspective on food analysis, together with a deep revision on the current state of the art of modern analytical instruments, methodologies, and applications in food analysis with a special emphasis on the works published on this topic in the last three years (2009–2011). The article also discusses the present and future challenges in food analysis, the application of “omics” in food analysis (including epigenomics, genomics, transcriptomics, proteomics, and metabolomics), and provides an overview on the new discipline of Foodomics.

Present and future challenges in food analysis: foodomics

The state-of-the-art of food analysis at the beginning of the 21st century is presented in this work, together with its major applications, current limitations, and present and foreseen challenges.

Protein-protein interactions in plants

The study of protein-protein interactions (PPIs) is essential to uncover unknown functions of proteins at the molecular level and to gain insight into complex cellular networks. Affinity purification and mass spectrometry (AP-MS), yeast two-hybrid, imaging approaches and numerous diverse databases have been developed as strategies to analyze PPIs. The past decade has seen an increase in the number of identified proteins with the development of MS and large-scale proteome analyses. Consequently, the false-positive protein identification rate has also increased. Therefore, the general consensus is to confirm PPI data using one or more independent approaches for an accurate evaluation. Furthermore, identifying minor PPIs is fundamental for understanding the functions of transient interactions and low-abundance proteins. Besides establishing PPI methodologies, we are now seeing the development of new methods and/or improvements in existing methods, which involve identifying minor proteins by MS, multidimensional protein identification technology or OFFGEL electrophoresis analyses, one-shot analysis with a long column or filter-aided sample preparation methods. These advanced techniques should allow thousands of proteins to be identified, whereas in-depth proteomic methods should permit the identification of transient binding or PPIs with weak affinity. Here, the current status of PPI analysis is reviewed and some advanced techniques are discussed briefly along with future challenges for plant proteomics.

Foodomics: MS-based strategies in modern food science and nutrition

Modern research in food science and nutrition is moving from classical methodologies to advanced analytical strategies in which MS-based techniques play a crucial role. In this context, Foodomics has been recently defined as a new discipline that studies food and nutrition domains through the application of advanced omics technologies in which MS techniques are considered indispensable. Applications of Foodomics include the genomic, transcriptomic, proteomic, and/or metabolomic study of foods for compound profiling, authenticity, and/or biomarker-detection related to food quality or safety; the development of new transgenic foods, food contaminants, and whole toxicity studies; new investigations on food bioactivity, food effects on human health, etc. This review work does not intend to provide an exhaustive revision of the many works published so far on food analysis using MS techniques. The aim of the present work is to provide an overview of the different MS-based strategies that have been (or can be) applied in the new field of Foodomics, discussing their advantages and drawbacks. Besides, some ideas about the foreseen development and applications of MS-techniques in this new discipline are also provided.

Metabolic adaptation in transplastomic plants massively accumulating recombinant proteins

BACKGROUND

Recombinant chloroplasts are endowed with an astonishing capacity to accumulate foreign proteins. However, knowledge about the impact on resident proteins of such high levels of recombinant protein accumulation is lacking.

METHODOLOGY/PRINCIPAL FINDINGS

Here we used proteomics to characterize tobacco (Nicotiana tabacum) plastid transformants massively accumulating a p-hydroxyphenyl pyruvate dioxygenase (HPPD) or a green fluorescent protein (GFP). While under the conditions used no obvious modifications in plant phenotype could be observed, these proteins accumulated to even higher levels than ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), the most abundant protein on the planet. This accumulation occurred at the expense of a limited number of leaf proteins including Rubisco. In particular, enzymes involved in CO(2) metabolism such as nuclear-encoded plastidial Calvin cycle enzymes and mitochondrial glycine decarboxylase were found to adjust their accumulation level to these novel physiological conditions.

CONCLUSIONS/SIGNIFICANCE

The results document how protein synthetic capacity is limited in plant cells. They may provide new avenues to evaluate possible bottlenecks in recombinant protein technology and to maintain plant fitness in future studies aiming at producing recombinant proteins of interest through chloroplast transformation.