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The ecological risks of transgenic plants.

Biotechnologies have been utilized "ante litteram" for thousands of years to produce food and drink and genetic engineering techniques have been widely applied to produce many compounds for human use, from insulin to other medicines. The debate on genetically modified (GM) organisms broke out all over the world only when GM crops were released into the field. Plant ecologists, microbiologists and population geneticists carried out experiments aimed at evaluating the environmental impact of GM crops. The most significant findings concern: the spread of transgenes through GM pollen diffusion and its environmental impact after hybridisation with closely related wild species or subspecies; horizontal gene transfer from transgenic plants to soil microbes; the impact of insecticide proteins released into the soil by transformed plants on non-target microbial soil communities. Recent developments in genetic engineering produced a technology, dubbed "Terminator", which protects patented genes introduced in transgenic plants by killing the seeds in the second generation. This genetic construct, which interferes so heavily with fundamental life processes, is considered dangerous and should be ex-ante evaluated taking into account the data on "unexpected events", as here discussed, instead of relying on the "safe until proven otherwise" claim. Awareness that scientists, biotechnologists and genetic engineers cannot answer the fundamental question "how likely is that transgenes will be transferred from cultivated plants into the natural environment?" should foster long-term studies on the ecological risks and benefits of transgenic crops.

Biotechnology↗

PubMed2006

Biodiversity and emerging diseases.

First we remind general considerations concerning biodiversity on earth and particularly the loss of genetic biodiversity that seems irreversible whether its origin is directly or indirectly linked to human activities. Urgent and considerable efforts must be made from now on to cataloge, understand, preserve, and enhance the value of biodiversity while ensuring food safety and human and animal health. Ambitious integrated and multifield research programs must be implemented in order to understand the causes and anticipate the consequences of loss of biodiversity. Such losses are a serious threat to sustainable development and to the quality of life of future generations. They have an influence on the natural balance of global biodiversity in particularly in reducing the capability of species to adapt rapidly by genetic mutations to survive in modified ecosystems. Usually, the natural immune systems of mammals (both human and animal), are highly polymorphic and able to adapt rapidly to new situations. We more specifically discuss the fact that if the genetic diversity of the affected populations is low the invading microorganisms, will suddenly expand and create epidemic outbreaks with risks of pandemic. So biodiversity appears to function as an important barrier (buffer), especially against disease-causing organisms, which can function in different ways. Finally, we discuss the importance of preserving biodiversity mainly in the wildlife ecosystems as an integrated and sustainable approach among others in order to prevent and control the emergence or reemergence of diseases in animals and humans (zoonosis). Although plants are also part of this paradigm, they fall outside our field of study.

Adaptation, Physiological↗

PubMed2005

Ultrasensitive reporter protein detection in genetically engineered bacteria.

We demonstrate the use of laser-induced fluorescence confocal spectroscopy to measure analyte-stimulated enhanced green fluorescent protein (egfp) synthesis by genetically modified Escherichia coli bioreporter cells. Induction is measured in cell lysates and, since the spectroscopic focal volume is approximately the size of one bioreporter cell, also in individual live bacteria. This is, to our knowledge, the first ever proof-of-concept work utilizing instrumentation with single-molecule detection capability to monitor bioreporter response. Although we use arsenic inducible bioreporters here, the method is extensible to gfp/egfp bioreporters that are responsive to other substances.

Arsenites↗

PubMed2001

Bacterial symbiosis and paratransgenic control of vector-borne Chagas disease.

The triatomine vectors of Chagas disease are obligate haematophagous insects, feeding on vertebrate blood throughout their entire developmental cycle. As a result of obtaining their nutrition from a single food source, their diet is devoid of certain vitamins and nutrients. Consequently, these insects harbour populations of bacterial symbionts within their intestinal tract, which provide the required nutrients that are lacking from their diet. We have isolated and characterised symbiont cultures from various triatomine species and developed a method for genetically transforming them. We can then reintroduce them into their original host species, thereby producing stable paratransgenic insects in which we are able to express heterologous gene products. Using this methodology, we have generated paratransgenic Rhodnius prolixus that are refractory for infection with Trypanosoma cruzi. Two examples of potentially refractory genes are currently being expressed in paratransgenic insects. These include the insect immune peptide cecropin A and active single chain antibody fragments. We have also developed an approach that would allow introduction of genetically modified bacterial symbionts into natural populations of Chagas disease vectors. This approach utilises the coprophagic behaviour of these insects, which is the way in which the symbionts are transmitted among bug populations in nature. The production and ultimate release of transgenic or paratransgenic insects for public health applications is potentially very promising but also worthy of much careful consideration with respect to environmental, political, and human safety concerns.

Animals↗

PubMed2003

The GM public debate: context and communication strategies.

Science communication is developing a new approach that promotes dialogue between scientists and the public. A recent example is the debate on the possible introduction of genetically modified crops into the United Kingdom. As this exercise in public engagement draws to a close, we consider the context in which this debate has taken place, and the challenges of developing such interactions between science and society.

Communication↗

PubMed2003

[Suppression of nonsense and frameshift mutations obtained by different methods for inactivating the translation termination factor eRF3 in yeast Saccharomyces cerevisiae].

Mutations in genes of omnipotent nonsense suppressors SUP35 and SUP45 in yeast Saccharomyces cerevisiae encoding translation termination factors eRF3 and eRF1, respectively, and prionization of the eRF3 protein may lead to the suppression of some frameshift mutations (CPC mutations). Partial inactivation of the translation termination factor eRF3 was studied in strains with unstable genetically modified prions and also in transgenic yeast S. cerevisiae strains with the substitution of the indigenous SUP35 gene for its homolog from Pichia methanolica or for a recombinant S. cerevisiae SUP35 gene. It was shown that this partial inactivation leads not only to nonsense suppression, but also to suppression of the frameshift lys2-90 mutation. Possible reasons for the correlation between nonsense suppression and suppression of the CPC lys2-90 mutation and mechanisms responsible for the suppression of CPC mutations during inactivation of translation termination factors are discussed.

Codon, Nonsense↗

PubMed2005

Reflecting on ethical and legal issues in wildlife disease.

Disease in wildlife raises a number of issues that have not been widely considered in the bioethical literature. However, wildlife disease has major implications for human welfare. The majority of emerging human infectious diseases are zoonotic: this is, they occur in humans by cross-species transmissions from animal hosts. Managing these diseases often involves balancing concerns with human health against animal welfare and conservation concerns. Many infectious diseases of domestic animals are shared with wild animals, although it is often unclear whether the infection spills over from wild animals to domestic animals or vice versa. Culling is the standard means of managing such diseases, bringing economic considerations, animal welfare and conservation into conflict. Infectious diseases are also major threatening processes in conservation biology and their appropriate management by culling, vaccination or treatment raises substantial animal ethics issues. One particular issue of great significance in Australia is an ongoing research program to develop genetically modified pathogens to control vertebrate pests including rabbits, foxes and house mice. Release of any self-replicating GMO vertebrate pathogen gives rise to a whole series of ethical questions. We briefly review current Australian legal responses to these problems. Finally, we present two unresolved problems of general importance that are exemplified by wildlife disease. First, to what extent can or should 'bioethics' be broadened beyond direct concerns with human welfare to animal welfare and environmental welfare? Second, how should the irreducible uncertainty of ecological systems be accounted for in ethical decision making?

Animal Welfare↗

PubMed2005

Ascomycete communities in the rhizosphere of field-grown wheat are not affected by introductions of genetically modified Pseudomonas putida WCS358r.

A long-term field experiment (1999-2002) was conducted to monitor effects on the indigenous microflora of Pseudomonas putida WCS358r and two transgenic derivatives constitutively producing phenazine-1-carboxylic acid (PCA) or 2,4-diacetylphloroglucinol (DAPG). The strains were introduced as seed coating on wheat into the same field plots each year. Rhizosphere populations of ascomycetes were analysed using denaturing gradient gel electrophoresis (DGGE). To evaluate the significance of changes caused by the genetically modified microorganisms (GMMs), they were compared with effects caused by a crop rotation from wheat to potato. In the first year, only the combination of both GMMs caused a significant shift in the ascomycete community. After the repeated introductions this effect was no longer evident. However, cropping potato significantly affected the ascomycete community. This effect persisted into the next year when wheat was grown. Clone libraries were constructed from samples taken in 1999 and 2000, and sequence analysis indicated ascomycetes of common genera to be present. Most species occurred in low frequencies, distributed almost evenly in all treatments. However, in 1999 Microdochium occurred in relatively high frequencies, whereas in the following year no Microdochium species were detected. On the other hand, Fusarium-like organisms were low in 1999, and increased in 2000. Both the DGGE and the sequence analysis revealed that repeated introduction of P. putida WCS358r had no major effects on the ascomycete community in the wheat rhizosphere, but demonstrated a persistent difference between the rhizospheres of potato and wheat.

Ascomycota↗

PubMed2005

Ingestion of milk fermented by genetically modified Lactococcus lactis improves the riboflavin status of deficient rats.

Riboflavin deficiency is common in many parts of the world, particularly in developing countries. The use of riboflavin-producing strains in the production of dairy products such as fermented milks, yogurts, and cheeses is feasible and economically attractive because it would decrease the costs involved during conventional vitamin fortification and satisfy consumer demands for healthier foods. The present study was conducted to assess in a rat bioassay the response of administration of milk fermented by modified Lactococcus lactis on the riboflavin status of deficient rats. Rats were fed a riboflavin-deficient diet during 21 d after which this same diet was supplemented with milk fermented by Lactoccus lactis pNZGBAH, a strain that overproduces riboflavin during fermentation. The novel fermented product, with increased levels of riboflavin, was able to eliminate most physiological manifestations of ariboflavinosis, such as stunted growth, elevated erythrocyte glutathione reductase activation coefficient values and hepatomegaly, that were observed using a riboflavin depletion-repletion model, whereas a product fermented with a nonriboflavin-producing strain did not show similar results. A safety assessment of this modified strain was performed by feeding rodents with the modified strain daily for 4 wk. This strain caused no detectable secondary effects. These results pave the way for analyzing the effect of similar riboflavin-overproducing lactic acid bacteria in human trials. The regular consumption of products with increased levels of riboflavin could help prevent deficiencies of this essential vitamin.

Animals↗

PubMed2003

Laboratory acquired infection with recombinant vaccinia virus containing an immunomodulating construct.

Handling of Vaccinia virus represents a risk for laboratory-acquired infections, especially in individuals without completed vaccination. We report the case of a Vaccinia infection in a previously vaccinated researcher working with various genetically modified strains. We could confirm the infection by electron microscopy, positive cell culture, virus-specific PCR, sequence analysis, and viral neutralization test. The isolated virus carried a functionally inactivated cytohesin-1 gene of human origin, which had been shown to impair leukocyte adhesion by interacting with the LFA/ICAM-1 axis. The immunomodulating nature of the inserted construct might thus have added to the infectivity of the virus. We emphasize on the necessity of Vaccinia vaccination in laboratory staff working in the field.

Adjuvants, Immunologic↗

PubMed2006

Genetically modified cyanobacterium Nostoc muscorum overproducing proline in response to salinity and osmotic stresses.

In the parent Nostoc muscorum an active proline oxidase enzyme is required to assimilate exogenous proline as a fixed nitrogen source. Cyanobacterial mutants, resistant to growth inhibitory action of proline analogue L-azetidine-2-carboxylate (Ac-R), were deficient in proline oxidase activity, and were over-accumulators of proline. Proline over-accumulation, resulting either from mutational acquisition of the Ac-R phenotype, or from salinity-induced uptake of exogenous proline, confirmed enhanced salinity/osmotic tolerance in the mutant strain. The nitrogenase activity and photosynthetic O 2 evolution of the parent were sensitive to both salinity as well as osmotic stresses than of Ac-R mutant strain. In addition, the mutation to Ac-resistant phenotype showed no alteration in salinity inducible potassium transport system in the cyanobacterium.

Azetidinecarboxylic Acid↗

PubMed2005

Molecular cloning, characterization, and downregulation of an acyltransferase that catalyzes the malonylation of flavonoid and naphthol glucosides in tobacco cells.

Tobacco cells (Nicotiana tabacum L. Bright Yellow T-13) exposed to harmful naphthols accumulate them as glucosylated and further modified compounds [Taguchi et al. (2003a) Plant Sci. 164, 231-240]. In this study, we identified the accumulated compounds to be 6'-O-malonylated glucosides of naphthols. Cells treated with various phenolic compounds accumulated the flavonoids mainly as malonylglucosides. To clarify the function of this malonylation in tobacco, we isolated the cDNA encoding a malonyltransferase (NtMaT1) from a cDNA library derived from tobacco cells. The heterologous expression of the gene in Escherichia coli revealed that the recombinant enzyme had malonyltransferase activity against several phenolic glucosides such as flavonoid 7-O-glucosides, flavonoid 3-O-glucosides and naphthol glucosides. The substrate preference of the enzyme was similar to that of the tobacco cell extract. Malonylation activity in the transgenic cells markedly decreased with the suppression of the expression of NtMaT1 mRNA in tobacco BY-2 cells by RNA interference. The compounds administered to the transgenic cells were accumulated in the cells as glucosides or other modified compounds in place of malonylglucosides. These results show that NtMaT1 is the main catalyst of malonylation on glucosides of xenobiotic flavonoids and naphthols in tobacco plants.

Acyltransferases↗

PubMed2004

The fate of a genetically modified Pseudomonas strain and its transgene during the composting of poultry manure.

The fate of the genetically modified (GM) Pseudomonas chlororaphis strain 3732 RN-L11 and its transgene (lacZ insert) during composting of chicken manure was studied using plate count and nested polymerase chain reaction (PCR) methods. The detection sensitivity of the nested PCR method was 165 copies of the modified gene per gram of moist compost or soil. Compost microcosms consisted of a 100-g mixture of chicken manure and peat, whereas soil microcosms were 100-g samples of sandy clay loam. Each microcosm was inoculated with 4 x 1010 CFU of P. chlororaphis RN-L11. In controlled temperature studies, neither P. chlororaphis RN-L11 nor its transgene could be detected in compost microcosms after incubation temperature was elevated to 45 degrees C or above for one or more days. In contrast, in the compost microcosms incubated at 23 degrees C, the target organism was not detected by the plate count method after 6 days, but its transgene was detectable for at least 45 days. In compost bins, the target organism was not recovered from compost microcosms or soil microcosms at different levels in the bins for 29 days. However, the transgene was detected in 8 of the 9 soil microcosms and in only 1 of the 9 compost microcosms. The compost microcosm in which transgene was detected was at the lower level of the bin where temperatures remained below 45 degrees C. The findings indicated that composting of organic wastes could be used to reduce or degrade heat sensitive GM microorganisms and their transgenes.

Animals↗

PubMed2005

[Genetically modified industrial brewing yeast with high-glutathione and low-diacetyl production].

Recombinant plasmid pICG was constructed by replacing the internal fragment of a-acetohydroxyacid synthase (AHAS) gene (ILV2) with a copy of gamma-glutamylcysteine synthetase gene (GSH1) and copper chelatin gene (CUP1) from the industrial brewing yeast strain YSF31. YSF31 was transformed with plasmid pICG linearized by Kpn I and Pst I. A recombinant strain with high-glutathione and low-diacetyl production was selected. The results of fermentation in 100-L bioreactor showed that the lagering time of beer produced for recombinant strain T2 was shortened by 3 days and the shelf life of the beer was prolonged about 50%. It may be more acceptable for the commercial application, as it does not contain foreign DNA.

Acetolactate Synthase↗

PubMed2006

[Effects of impaction on tissue engineered bone modified by BMP-2 gene].

OBJECTIVE: To observe effects of the direct impaction on the cell survival and the bone formation of the tissue engineered bone modified by the adenovirus mediated human bone morphogenetic protein 2 (Adv-hBMP2) gene and to verify the feasibility of the impacted grafting with it. METHODS: The marrow stromal cells (MSCs) were separated from the canine bone marrow and were cultured. MSCs were transfected with the Adv-hBMP2 gene and combined with the freeze-dried cancellous bone (FDB) to form the tissue engineered bone. Four days after the combination, the tissue engineered bone was impacted in a simulated impactor in vitro and implanted in the mouse. The cell survivals were evaluated with SEM 1 and 4 days after the combination, immediately after the impaction, and 1 and 4 days after the impaction, respectively. The bone formation and the allograft absorption were histologically evaluated respectively. RESULTS: There were multiple layers of the cells and much collagen on FDB before the impaction. Immediately after the impaction, most of the cells on the direct contact area disappeared and there was much debris on the section. Some of the cells died and separated from the surface of FDB at 1 day, the number of the cells decreased but the collagen increased on the surface at 4 days. Histologically, only the fibrous tissue was found in FDB without the cells, the bone formation on FDB was even in distribution and mass in appearance before the impaction, but declined and was mainly on the periphery after the impaction in the Adv-hBMP-2 modified tissue-engineered bone. CONCLUSION: The simulated impaction can decrease the cells survival and the bone formation of the Adv-hBMP-2 modified tissue-engineered bone. The survival cells still function well. It is feasible to use the tissue engineered bone in the impaction graft.

Adenoviridae↗

PubMed2002

The human minisatellites MS1, MS32, MS205 and CEB1 integrated into the yeast genome exhibit different degrees of mitotic instability but are all stabilised by RAD27.

The yeast Rad27 protein is homologous to mammalian Fen1 and is involved in the processing of replication intermediates. Enhanced instability of various artificial repetitive DNA sequences in RAD27-deficient yeast strains has been observed previously and shown to involve preferentially expansion mutations. In the present investigation, we characterised the mitotic instability of alleles of the naturally occurring human minisatellites MS1, MS32, MS205 and CEB1 and the modified MS1 alleles containing more highly homogeneous repeat regions than the original alleles. These minisatellites demonstrated more pronounced instability in rad27 Delta strains, with increases in the frequencies of both expansion and contraction mutants. In RAD27 strains, MS32 and MS205 were relatively stable, while MS1 and CEB1 were unstable, indicating that the effect of RAD27 on stability is influenced by intrinsic properties of the repeat array. This conclusion received further support from the remarkably high frequency of length-mutants observed for the modified allele of MS1. Thus, our findings emphasise the importance of: (1) comparing results obtained with various naturally occurring minisatellites and (2) manipulating their sequences in attempts to understand the molecular basis for mitotic stability/instability of minisatellite DNA.

Base Sequence↗

PubMed2006

Whole-cell living biosensors--are they ready for environmental application?

Since the development of the first whole-cell living biosensor or bioreporter about 15 years ago, construction and testing of new genetically modified microorganisms for environmental sensing and reporting has proceeded at an ever increasing rate. One and a half decades appear as a reasonable time span for a new technology to reach the maturity needed for application and commercial success. It seems, however, that the research into cellular biosensors is still mostly in a proof-of-principle or demonstration phase and not close to extensive or commercial use outside of academia. In this review, we consider the motivations for bioreporter developments and discuss the suitability of extant bioreporters for the proposed applications to stimulate complementary research and to help researchers to develop realistic objectives. This includes the identification of some popular misconceptions about the qualities and shortcomings of bioreporters.

Bacteria↗

PubMed2026

Hypoimmune platforms: from rejection to immune evasion and regulatory implications.

The growing gap between organ demand and clinical availability has renewed interest in immune-evasive graft strategies, yet rejection and lifelong immunosuppression remain major barriers to durable success. Advances in genome editing enable immune-evasive cell platforms designed to avoid immune recognition while replacing missing function in allogeneic settings. This review summarizes current strategies for engineering immune-evasive grafts that simultaneously suppress adaptive and innate immune responses. We discuss how coordinated modulation of antigen presentation and immune checkpoint pathways can protect transplanted allogeneic cells and tissues from T, NK, and macrophage-mediated rejection. We also present the emerging concept of integrating hypoimmune engineering with genetically modified porcine donors, where extensive genome editing has reduced, but not eliminated, xenogeneic immune barriers. Combining donor genome modification with immune-evasive graft design represents a promising conceptual advance toward xenograft survival, though whether full elimination of systemic immunosuppression is achievable remains to be established clinically. We further examine how the regulatory landscape for these products is evolving across major jurisdictions, and how differences in approval pathways, manufacturing standards, and long-term surveillance requirements shape the path to clinical translation. Finally, we outline the safety considerations and remaining limitations in immune evasion that must be addressed to enable clinical implementation.

Graft Rejection↗