Safety assessment of recombinant green fluorescent protein orally administered to weaned rats

Overview of cloning in lactic acid bacteria: Expression and its application of probiotic potential in inflammatory bowel diseases

Inflammatory bowel disease (IBD) imposes a significant impact on the quality of life for affected individuals. However, there was a current lack of a systematic summary regarding the latest epidemic trends and the underlying pathogenesis of IBD. This highlights the need for a thorough examination of both the epidemiological aspects of IBD and the specific mechanisms by which lactic acid bacteria (LAB) contribute to mitigating this condition. In developed countries, higher incidences and death rates of IBD have been observed, influenced by a combination of environmental and genetic factors. LAB offer significant advantages and substantial potential for enhancing IBD treatment. LAB's capabilities include the production of bioactive metabolites, regulation of gut immunity, protection of intestinal mechanical barriers, inhibition of oxidative damage, and restoration of imbalanced gut microbiota. The review suggests that screening effective LAB using cell models and metabolites, optimizing LAB intake through dose-effect studies, enhancing utilization through nanoencapsulation and microencapsulation, investigating mechanisms to deepen the understanding of LAB, and refining clinical study designs. These efforts aim to contribute to comprehending the epidemic trend, pathogenesis, and treatment of IBD, ultimately fostering the development of targeted therapeutic products, such as LAB-based interventions.

Bioinformatic and literature assessment of toxicity and allergenicity of a CRISPR-Cas9 engineered gene drive to control Anopheles gambiae the mosquito vector of human malaria

BACKGROUND

Population suppression gene drive is currently being evaluated, including via environmental risk assessment (ERA), for malaria vector control. One such gene drive involves the dsxFCRISPRh transgene encoding (i) hCas9 endonuclease, (ii) T1 guide RNA (gRNA) targeting the doublesex locus, and (iii) DsRed fluorescent marker protein, in genetically-modified mosquitoes (GMMs). Problem formulation, the first stage of ERA, for environmental releases of dsxFCRISPRh previously identified nine potential harms to the environment or health that could occur, should expressed products of the transgene cause allergenicity or toxicity.

METHODS

Amino acid sequences of hCas9 and DsRed were interrogated against those of toxins or allergens from NCBI, UniProt, COMPARE and AllergenOnline bioinformatic databases and the gRNA was compared with microRNAs from the miRBase database for potential impacts on gene expression associated with toxicity or allergenicity. PubMed was also searched for any evidence of toxicity or allergenicity of Cas9 or DsRed, or of the donor organisms from which these products were originally derived.

RESULTS

While Cas9 nuclease activity can be toxic to some cell types in vitro and hCas9 was found to share homology with the prokaryotic toxin VapC, there was no evidence from previous studies of a risk of toxicity to humans and other animals from hCas9. Although hCas9 did contain an 8-mer epitope found in the latex allergen Hev b 9, the full amino acid sequence of hCas9 was not homologous to any known allergens. Combined with a lack of evidence in the literature of Cas9 allergenicity, this indicated negligible risk to humans of allergenicity from hCas9. No matches were found between the gRNA and microRNAs from either Anopheles or humans. Moreover, potential exposure to dsxFCRISPRh transgenic proteins from environmental releases was assessed as negligible.

CONCLUSIONS

Bioinformatic and literature assessments found no convincing evidence to suggest that transgenic products expressed from dsxFCRISPRh were allergens or toxins, indicating that environmental releases of this population suppression gene drive for malaria vector control should not result in any increased allergenicity or toxicity in humans or animals. These results should also inform evaluations of other GMMs being developed for vector control and in vivo clinical applications of CRISPR-Cas9.

Edible Matrix Code with Photogenic Silk Proteins

Counterfeit medicines are a healthcare security problem, posing not only a direct threat to patient safety and public health but also causing heavy economic losses. Current anticounterfeiting methods are limited due to the toxicity of the constituent materials and the focus of secondary packaging level protections. We introduce an edible, imperceptible, and scalable matrix code of information representation and data storage for pharmaceutical products. This matrix code is digestible as it is composed of silk fibroin genetically encoded with fluorescent proteins produced by ecofriendly, sustainable silkworm farming. Three distinct fluorescence emission colors are incorporated into a multidimensional parameter space with a variable encoding capacity in a format of matrix arrays. This code is smartphone-readable to extract a digitized security key augmented by a deep neural network for overcoming fabrication imperfections and a cryptographic hash function for enhanced security. The biocompatibility, photostability, thermal stability, long-term reliability, and low bit error ratio of the code support the immediate feasibility for dosage-level anticounterfeit measures and authentication features. The edible code affixed to each medicine can serve as serialization, track and trace, and authentication at the dosage level, empowering every patient to play a role in combating illicit pharmaceuticals.

Toward the Definition of Efficacy and Safety Criteria for Advancing Gene Drive-Modified Mosquitoes to Field Testing

Mosquitoes containing gene drive systems are being developed as complementary tools to prevent transmission of malaria and other mosquito-borne diseases. As with any new tool, decision makers and other stakeholders will need to balance risks (safety) and benefits (efficacy) when considering the rationale for testing and deploying gene drive-modified mosquito products. Developers will benefit from standards for judging whether an investigational gene drive product meets acceptability criteria for advancing to field trials. Such standards may be formalized as preferred product characteristics and target product profiles, which describe the desired attributes of the product category and of a particular product, respectively. This report summarizes discussions from two scientific workshops aimed at identifying efficacy and safety characteristics that must be minimally met for an investigational gene drive-modified mosquito product to be deemed viable to move from contained testing to field release and the data that will be needed to support an application for first field release.

Edible unclonable functions

Counterfeit medicines are a fundamental security problem. Counterfeiting medication poses a tremendous threat to patient safety, public health, and the economy in developed and less developed countries. Current solutions are often vulnerable due to the limited security levels. We propose that the highest protection against counterfeit medicines would be a combination of a physically unclonable function (PUF) with on-dose authentication. A PUF can provide a digital fingerprint with multiple pairs of input challenges and output responses. On-dose authentication can verify every individual pill without removing the identification tag. Here, we report on-dose PUFs that can be directly attached onto the surface of medicines, be swallowed, and digested. Fluorescent proteins and silk proteins serve as edible photonic biomaterials and the photoluminescent properties provide parametric support of challenge-response pairs. Such edible cryptographic primitives can play an important role in pharmaceutical anti-counterfeiting and other security applications requiring immediate destruction or vanishing features.

Construction of a shuttle expression vector for lactic acid bacteria

Background

Lactic acid bacteria (LAB) are a diverse group of Gram-positive bacteria, which are widely distributed in various diverse natural habitats. These are used in a variety of industrial food fermentations and carry numerous traits with utmost relevance to the food industry. Genetic engineering has emerged as an effective means to improve and enhance the potential of commercially important bacterial strains. However, the biosafety of recombinant systems is an important concern during the implementation of such technologies on an industrial scale. In order to overcome this issue, cloning and expression systems have been developed preferably from fully characterized and annotated LAB plasmids encoding genes with known functions.

Results

The developed shuttle vector pPBT-GFP contains two theta-type replicons with a copy number of 4.4 and 2.8 in Pediococcus acidilactici MTCC 5101 and Lactobacillus brevis MTCC 1750, respectively. Antimicrobial “pediocin” produced by P. acidilactici MTCC 5101 and green fluorescent protein (GFP) of Aequorea victoria were successfully expressed as selectable markers. Heterologous bile salt hydrolase (BSH) from Lactobacillus fermentum NCDO 394 has been efficiently expressed in the host strains showing high specific activity of 126.12 ± 10.62 in P. acidilactici MTCC 5101 and 95.43 ± 4.26 in the case of L. brevis MTCC 1750, towards glycine-conjugated bile salts preferably as compared to taurine-conjugated salts.

Conclusion

The present article details the development of a LAB/LAB shuttle expression vector pPBT-GFP, capable of replication in LAB hosts, P. acidilactici MTCC 5101, and L. brevis MTCC 1750. Pediocin and GFP have been used as selectable markers with the efficient production of heterologous extracellular bile salt hydrolase. Thus, the constructed vector pPBT-GFP, with its ability to replicate in multiple hosts, low copy number, and stability in host cells, may serve as an ideal tool for improving LAB strains of commercial value using genetic engineering.

Ecofriendly and Efficient Luminescent Solar Concentrators Based on Fluorescent Proteins

In recent years, luminescent solar concentrators (LSCs) have received renewed attention as a versatile platform for large-area, high-efficiency, and low-cost solar energy harvesting. So far, artificial or engineered optical materials, such as rare-earth ions, organic dyes, and colloidal quantum dots (QDs) have been incorporated into LSCs. Incorporation of nontoxic materials into efficient device architectures is critical for environmental sustainability and clean energy production. Here, we demonstrated LSCs based on fluorescent proteins, which are biologically produced, ecofriendly, and edible luminescent biomaterials along with exceptional optical properties. We synthesized mScarlet fluorescent proteins in Escherichia coli expression system, which is the brightest protein with a quantum yield of 61% in red spectral region that matches well with the spectral response of silicon solar cells. Moreover, we integrated fluorescent proteins in an aqueous medium into solar concentrators, which preserved their quantum efficiency in LSCs and separated luminescence and wave-guiding regions due to refractive index contrast for efficient energy harvesting. Solar concentrators based on mScarlet fluorescent proteins achieved an external LSC efficiency of 2.58%, and the integration at high concentrations increased their efficiency approaching to 5%, which may facilitate their use as "luminescent solar curtains" for in-house applications. The liquid-state integration of proteins paves a way toward efficient and "green" solar energy harvesting.

The aryloxyalkanoate dioxygenase-12 (AAD-12) protein is not acutely toxic in mice

Typically, when a protein is orally toxic, it acts via acute mechanisms, especially at high doses. Therefore, an acute oral toxicity study is considered appropriate for evaluating the safety of transgenic proteins. Soybean plants (events DAS-68416-4 and DAS-444Ø6-6) have been genetically modified to express the aryloxyalkanoate dioxygenase-12 (AAD-12) protein. The AAD-12 protein provides tolerance to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). This paper summarizes the study designs of two acute oral toxicity studies evaluating the AAD-12 protein and reports the results of these studies. No mortalities or adverse effects were observed in mice when AAD-12 was tested up to a limit dose of 5000 mg/kg body weight. Based on the results of these studies, it can be concluded that AAD-12 protein, as expressed in genetically modified DAS-68416-4 and DAS-444Ø6-6 soybeans, lacks acute toxicity via the oral route.

Adaptation of the ToxRTool to Assess the Reliability of Toxicology Studies Conducted with Genetically Modified Crops and Implications for Future Safety Testing

To determine the reliability of food safety studies carried out in rodents with genetically modified (GM) crops, a Food Safety Study Reliability Tool (FSSRTool) was adapted from the European Centre for the Validation of Alternative Methods' (ECVAM) ToxRTool. Reliability was defined as the inherent quality of the study with regard to use of standardized testing methodology, full documentation of experimental procedures and results, and the plausibility of the findings. Codex guidelines for GM crop safety evaluations indicate toxicology studies are not needed when comparability of the GM crop to its conventional counterpart has been demonstrated. This guidance notwithstanding, animal feeding studies have routinely been conducted with GM crops, but their conclusions on safety are not always consistent. To accurately evaluate potential risks from GM crops, risk assessors need clearly interpretable results from reliable studies. The development of the FSSRTool, which provides the user with a means of assessing the reliability of a toxicology study to inform risk assessment, is discussed. Its application to the body of literature on GM crop food safety studies demonstrates that reliable studies report no toxicologically relevant differences between rodents fed GM crops or their non-GM comparators.

A 90-day toxicology study of meat from genetically modified sheep overexpressing TLR4 in Sprague-Dawley rats

Genetic modification offers alternative strategies to traditional animal breeding. However, the food safety of genetically modified (GM) animals has attracted increasing levels of concern. In this study, we produced GM sheep overexpressing TLR4, and the transgene-positive offsprings (F1) were confirmed using the polymerase chain reaction (PCR) and Southern blot. The expression of TLR4 was 2.5-fold compared with that of the wild-type (WT) sheep samples. During the 90-day safety study, Sprague-Dawley rats were fed with three different dietary concentrations (3.75%, 7.5%, and 15% wt/wt) of GM sheep meat, WT sheep meat or a commercial diet (CD). Blood samples from the rats were collected and analyzed for hematological and biochemical parameters, and then compared with hematological and biochemical reference ranges. Despite a few significant differences among the three groups in some parameters, all other values remained within the normal reference intervals and thus were not considered to be affected by the treatment. No adverse diet-related differences in body weights or relative organ weights were observed. Furthermore, no differences were observed in the gross necropsy findings or microscopic pathology of the rats whose diets contained the GM sheep meat compared with rats whose diets contained the WT sheep meat. Therefore, the present 90-day rat feeding study suggested that the meat of GM sheep overexpressing TLR4 had no adverse effect on Sprague-Dawley rats in comparison with WT sheep meat. These results provide valuable information regarding the safety assessment of meat derived from GM animals.

Reducing blood glucose levels in TIDM mice with an orally administered extract of sericin from hIGF-I-transgenic silkworm cocoons

In previous studies, we reported that the blood glucose levels of mice with type I diabetes mellitus (TIDM) was reduced with orally administered silk gland powder from silkworms transgenic for human insulin-like growth factor-I (hIGF-I). However, potential safety hazards could not be eliminated because the transgenic silk gland powder contained heterologous DNA, including the green fluorescent protein (gfp) and neomycin resistance (neo) genes. These shortcomings might be overcome if the recombinant hIGF-I were secreted into the sericin layer of the cocoon. In this study, silkworm eggs were transfected with a novel piggyBac transposon vector, pigA3GFP-serHS-hIGF-I-neo, containing the neo, gfp, and hIGF-I genes controlled by the sericin-1 (ser-1) promoter with the signal peptide DNA sequence of the fibrin heavy chain (Fib-H) and a helper plasmid containing the piggyBac transposase sequence under the control of the Bombyx mori actin 3 (A3) promoter, using sperm-mediated gene transfer to generate the transformed silkworms. The hIGF-I content estimated by enzyme-linked immunosorbent assay was approximately 162.7 ng/g. To estimate the biological activity of the expressed hIGF-I, streptozotocin-induced TIDM mice were orally administered sericin from the transgenic silkworm. The blood glucose levels of the mice were significantly reduced, suggesting that the extract from the transgenic hIGF-I silkworm cocoons can be used as an orally administered drug.

Iron bioavailability of maize hemoglobin in a Caco-2 cell culture model

Maize ( Zea mays ) is an important staple crop in many parts of the world but has low iron bioavailability, in part due to its high phytate content. Hemoglobin is a form of iron that is highly bioavailable, and its bioavailability is not inhibited by phytate. It was hypothesized that maize hemoglobin is a highly bioavailable iron source and that biofortification of maize with iron can be accomplished by overexpression of maize globin in the endosperm. Maize was transformed with a gene construct encoding a translational fusion of maize globin and green fluorescent protein under transcriptional control of the maize 27 kDa γ-zein promoter. Iron bioavailability of maize hemoglobin produced in Escherichia coli and of stably transformed seeds expressing the maize globin-GFP fusion was determined using an in vitro Caco-2 cell culture model. Maize flour fortified with maize hemoglobin was found to have iron bioavailability that is not significantly different from that of flour fortified with ferrous sulfate or bovine hemoglobin but is significantly higher than unfortified flour. Transformed maize grain expressing maize globin was found to have iron bioavailability similar to that of untransformed seeds. These results suggest that maize globin produced in E. coli may be an effective iron fortificant, but overexpressing maize globin in maize endosperm may require a different strategy to increase bioavailable iron content in maize.

Oral ingestion of transgenic RIDL Ae. aegypti larvae has no negative effect on two predator Toxorhynchites species

Dengue is the most important mosquito-borne viral disease. No specific treatment or vaccine is currently available; traditional vector control methods can rarely achieve adequate control. Recently, the RIDL (Release of Insect carrying Dominant Lethality) approach has been developed, based on the sterile insect technique, in which genetically engineered ‘sterile’ homozygous RIDL male insects are released to mate wild females; the offspring inherit a copy of the RIDL construct and die. A RIDL strain of the dengue mosquito, Aedes aegypti, OX513A, expresses a fluorescent marker gene for identification (DsRed2) and a protein (tTAV) that causes the offspring to die. We examined whether these proteins could adversely affect predators that may feed on the insect. Aedes aegypti is a peri-domestic mosquito that typically breeds in small, rain-water-filled containers and has no specific predators. Toxorhynchites larvae feed on small aquatic organisms and are easily reared in the laboratory where they can be fed exclusively on mosquito larvae. To evaluate the effect of a predator feeding on a diet of RIDL insects, OX513A Ae. aegypti larvae were fed to two different species of Toxorhynchites (Tx. splendens and Tx. amboinensis) and effects on life table parameters of all life stages were compared to being fed on wild type larvae. No significant negative effect was observed on any life table parameter studied; this outcome and the benign nature of the expressed proteins (tTAV and DsRed2) indicate that Ae. aegypti OX513A RIDL strain is unlikely to have any adverse effects on predators in the environment.

Visual selection allows immediate identification of transgenic rice calli efficiently accumulating transgene products

In genetic transformation systems, antibiotic resistance genes are routinely used as powerful markers for selecting transformed cells from surrounding non-transformed cells. However, simultaneous use of the gene encoding green fluorescent protein (GFP) and an antibiotic resistance gene facilitates the selection process, since it allows visible selection of transformed cells. Here, we report the development of a visual selection system for transformed cells using a GFP marker without selection against antibiotics after Agrobacterium-mediated transformation in rice. Both GFP protein levels and GFP fluorescence in calli isolated by visual selection were higher than in calli selected on hygromycin (Hyg), suggesting that transgenic calli hyper-accumulating GFP were efficiently obtained by selection using GFP fluorescence itself rather than Hyg resistance. Furthermore, gfp transcripts in calli isolated by visual selection were more abundant than under Hyg selection; in contrast, transcript levels of hpt in calli selected visually were comparable to those obtained under Hyg selection. These results suggest that there was no correlation between hpt and gfp expression levels, despite the fact that they are aligned in tandem on an integrated locus after selection by either GFP fluorescence or Hyg resistance. This fact indicates that positional effects can influence the expression of each transgene differently, even when they are located in tandem at the same locus. In summary, based on our results, we discuss a model system for rice cell culture transformation for the production of recombinant proteins using visual selection.

Health risks of genetically modified foods

As genetically modified (GM) foods are starting to intrude in our diet concerns have been expressed regarding GM food safety. These concerns as well as the limitations of the procedures followed in the evaluation of their safety are presented. Animal toxicity studies with certain GM foods have shown that they may toxically affect several organs and systems. The review of these studies should not be conducted separately for each GM food, but according to the effects exerted on certain organs it may help us create a better picture of the possible health effects on human beings. The results of most studies with GM foods indicate that they may cause some common toxic effects such as hepatic, pancreatic, renal, or reproductive effects and may alter the hematological, biochemical, and immunologic parameters. However, many years of research with animals and clinical trials are required for this assessment. The use of recombinant GH or its expression in animals should be re-examined since it has been shown that it increases IGF-1 which may promote cancer.

Safety assessment of bacterial choline oxidase protein introduced in transgenic crops for tolerance against abiotic stress

Genetically modified crops have resistance to abiotic stress by introduction of choline oxidase protein. In the present study, the safety of choline oxidase protein derived from Arthrobacter globiformis was assessed for toxicity and allergenicity. The protein was stable at 90 degrees C for 1 h. Toxicity studies of choline oxidase in mice showed no significant difference (p > 0.05) from control in terms of growth, body weight, food consumption, and blood biochemical indices. Histology of gut tissue of mice fed protein showed normal gastric mucosal lining and villi in jejunum and ileum sections. Specific IgE in serum and IL-4 release in splenic culture supernatant were low in choline oxidase treated mice, comparable to control. Intravenous challenge with choline oxidase did not induce any adverse reaction, unlike ovalbumin group mice. Histology of lung tissues from choline oxidase sensitized mice showed normal airways, whereas ovalbumin-sensitized mice showed inflamed airways with eosinophilic infiltration and bronchoconstriction. ELISA carried out with food allergic patients' sera revealed no significant IgE affinity with choline oxidase. Also, choline oxidase did not show any symptoms of toxicity and allergenicity in mice.

Toxicity studies of genetically modified plants: a review of the published literature

According to the information reported by the WHO, the genetically modified (GM) products that are currently on the international market have all passed risk assessments conducted by national authorities. These assessments have not indicated any risk to human health. In spite of this clear statement, it is quite amazing to note that the review articles published in international scientific journals during the current decade did not find, or the number was particularly small, references concerning human and animal toxicological/health risks studies on GM foods. In this paper, the scientific information concerning the potential toxicity of GM/transgenic plants using the Medline database is reviewed. Studies about the safety of the potential use of potatoes, corn, soybeans, rice, cucumber, tomatoes, sweet pepper, peas, and canola plants for food and feed were included. The number of references was surprisingly limited. Moreover, most published studies were not performed by the biotechnology companies that produce these products. This review can be concluded raising the following question: where is the scientific evidence showing that GM plants/food are toxicologically safe?

Enhanced antitumor efficacy of telomerase-selective oncolytic adenoviral agent OBP-401 with docetaxel: preclinical evaluation of chemovirotherapy

Oncolytic adenoviruses are being developed as novel anticancer therapeutics and currently undergoing clinical trials. We previously demonstrated that telomerase-specific replication-competent adenovirus (Telomelysin: OBP-301), in which the human telomerase reverse transcriptase (hTERT) promoter regulates viral replication, efficiently killed human tumor cells. We further constructed OBP-401 (Telomelysin-GFP) that expresses the green fluorescent protein (GFP) reporter gene under the control of the cytomegalovirus promoter in the E3 region to monitor viral distribution. Here, we examined the feasibility of a single-agent therapy with OBP-401 as well as of combining OBP-401 with chemotherapeutic agents. Infection of OBP-401 alone or followed by the treatment of a chemotherapeutic drug, docetaxel (Taxotere), resulted in a profound in vitro cytotoxicity and GFP expression in various human cancer cell lines originating from different organs (lung, colon, esophagus, stomach, liver and prostate), although the magnitude of antitumor effect varied among the cell types. Other chemotherapeutic drugs such as vinorelbine (Navelbine) and SN38 (the potent active metabolite of irinotecan) combined with OBP-401 also inhibited the growth of human cancer cells. Quantitative real-time PCR analysis demonstrated that docetaxel did not affect viral replication. For in vivo evaluation, nu/nu mice xenografted with H1299 human lung tumor received intratumoral injection of OBP-401 and intraperitoneal administration of docetaxel. Analysis of growth of implanted tumors showed a significant, therapeutic synergism, although OBP-401 alone and docetaxel alone showed modest inhibition of tumor growth. Thus, OBP-401 in combination with docetaxel efficiently enhances the antitumor efficacy both in vitro and in vivo, and the outcome has important implications for tumor-specific oncolytic chemovirotherapies for human cancers.

Go with the glow: fluorescent proteins to light transgenic organisms

Once a biological novelty known for their role in bioluminescence, fluorescent proteins (FPs) from marine invertebrates have revolutionized the life sciences. Organisms from all kingdoms have been transformed with the Aequorea victoria green fluorescent protein (GFP), and biotechnology has been advanced by the use of FPs. This article reviews the current uses of FPs in whole transgenic organisms and genomics and looks beyond GFP to the complete color palette and spectral properties afforded by FPs from other marine organisms. Coupled with electronic devices for visualizing and quantifying FPs, recently cloned FP genes might be useful for the ecological monitoring of transgenic organisms in the environment. Therefore, this review also addresses the in vivo labeling of organisms with an emphasis on plants.

Biosafety considerations for selectable and scorable markers used in cassava (Manihot esculentaCrantz) biotechnology

Cassava is an important subsistence crop grown only in the tropics, and represents a major source of calories for many people in developing countries. Improvements in the areas of resistance to insects and viral diseases, enhanced nutritional qualities, reduced cyanogenic content and modified starch characteristics are urgently needed. Traditional breeding is hampered by the nature of the crop, which has a high degree of heterozygosity, irregular flowering, and poor seed set. Biotechnology has the potential to enhance crop improvement efforts, and genetic engineering techniques for cassava have thus been developed over the past decade. Selectable and scorable markers are critical to efficient transformation technology, and must be evaluated for biosafety, as well as efficiency and cost-effectiveness. In order to facilitate research planning and regulatory submission, the literature on biosafety aspects of the selectable and scorable markers currently used in cassava biotechnology is surveyed. The source, mode of action and current use of each marker gene is described. The potential for toxicity, allergenicity, pleiotropic effects, horizontal gene transfer, and the impact of these on food or feed safety and environmental safety is evaluated. Based on extensive information, the selectable marker genes nptII, hpt, bar/pat, and manA, and the scorable marker gene uidA, all have little risk in terms of biosafety. These appear to represent the safest options for use in cassava biotechnology available at this time.

Regulating transgenic crops sensibly: lessons from plant breeding, biotechnology and genomics

The costs of meeting regulatory requirements and market restrictions guided by regulatory criteria are substantial impediments to the commercialization of transgenic crops. Although a cautious approach may have been prudent initially, we argue that some regulatory requirements can now be modified to reduce costs and uncertainty without compromising safety. Long-accepted plant breeding methods for incorporating new diversity into crop varieties, experience from two decades of research on and commercialization of transgenic crops, and expanding knowledge of plant genome structure and dynamics all indicate that if a gene or trait is safe, the genetic engineering process itself presents little potential for unexpected consequences that would not be identified or eliminated in the variety development process before commercialization. We propose that as in conventional breeding, regulatory emphasis should be on phenotypic rather than genomic characteristics once a gene or trait has been shown to be safe.

Monitoring the presence and expression of transgenes in living plants

A range of bio- and nanotechnologies have been developed that could be adapted towards monitoring the presence and expression of transgenes, in real time and in the field, in plants of agronomic and ecological importance. Transgene escape from crop hosts to wild relatives or landraces is one example in which monitoring might be useful, depending on the ecological impact of the transgene. In addition, there might be non-biosafety-related practical reasons to monitor transgene expression. Transgenes can be tagged with green fluorescent protein and imaged or measured using instruments designed to detect fluorescence signals on the plant. In addition, nanotechnologies using aptamers, quantum dots and molecular beacons are rapidly evolving and could also be used for post hoc (after transformation) in vivo monitoring. These nanotechnologies have the benefit of being useful on a post hoc basis.

Tracking genes from seed to supermarket: techniques and trends

Analytical techniques to track plant genes in the environment and the food chain are essential for environmental risk assessment, government regulation and production and trade of genetically modified (GM) crops. Here, I review laboratory techniques to track plant genes during pre-commercialization research on gene flow and post-commercialization detection, identification and quantification of GM crops from seed to supermarket. At present, DNA- and protein-based assays support both activities but the demand for fast, inexpensive, sensitive methods is increasing. Part of the demand has been generated by stringent food labeling and traceability regulations for GM crops. The increase in GM crops, changes in GM crop design, evolution of government regulations and adoption of risk-assessment frameworks will continue to drive development of analytical techniques.