PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Organisms, Genetically Modified”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources
PubMed2000

Population structure and evolutionary dynamics of pathogenic bacteria.

Evidence concerning the significance of recombination within natural bacterial populations has historically come from two main sources: multilocus enzyme electrophoresis (MLEE) and nucleotide sequence data. Here we discuss evidence from a third method, multilocus sequence typing (MLST), which is a development of MLEE based on nucleotide sequencing that combines the advantages of both approaches. MLST has confirmed both the existence of clones and the high rates of recombination for several bacterial pathogens. The data are consistent with "epidemic" population structures, where clones are superimposed upon a backdrop of frequent recombination, thus, in the short term, resisting the homogenising effect of recombination. The nature of the selective advantage of clones, however, and how this advantage relates to virulence are unclear. The current evidence also has broader implications concerning bacterial species definition, the management of antibiotic-resistant bacteria and the assessment of the dangers of releasing genetically modified organisms into the environment.

Bacteria↗
PubMed2001

Electrochemical biosensors for evaluation of contaminants in food.

This paper describes the application of electrochemical disposable biosensors in food analysis, which have recently been developed in our laboratory. Disposable biosensors, based on acetylcholinesterase inhibition activity, were exploited for testing the presence of organophosphorus and carbamate pesticides in water, fruit, and vegetable samples. The paper further describes preliminary tests for the detection of genetically modified organisms and hybridisation by coupling the DNA biosensors with the polymerase chain reaction.

Biosensing Techniques↗
PubMed2006

Event-specific qualitative and quantitative polymerase chain reaction analysis for genetically modified canola T45.

Polymerase chain reaction (PCR) methods have been the main technical support for the detection of genetically modified organisms (GMOs). To date, GMO-specific PCR detection strategies have been developed basically at four different levels, such as screening-, gene-, construct-, and event-specific detection methods. Event-specific PCR detection method is the primary trend in GMO detection because of its high specificity based on the flanking sequence of exogenous integrant. GM canola, event T45, with tolerance to glufosinate ammonium is one of the commercial genetically modified (GM) canola events approved in China. In this study, the 5'-integration junction sequence between host plant DNA and the integrated gene construct of T45 canola was cloned and revealed by means of TAIL-PCR. Specific PCR primers and TaqMan probes were designed based upon the revealed sequence, and qualitative and quantitative TaqMan real-time PCR detection assays employing these primers and probe were developed. In qualitative PCR, the limit of detection (LOD) was 0.1% for T45 canola in 100 ng of genomic DNA. The quantitative PCR assay showed limits of detection and quantification (LOD and LOQ) of 5 and 50 haploid genome copies, respectively. In addition, three mixed canola samples with known GM contents were detected employing the developed real-time PCR assay, and expected results were obtained. These results indicated that the developed event-specific PCR methods can be used for identification and quantification of T45 canola and its derivates.

Base Sequence↗
PubMed2002

Appetising solutions: an edible vaccine for measles.

The cultivation of plants with specific properties has been the foundation of medicine for milennia. Modern biotechnology may one day extend their medicinal uses to include the delivery of vaccines. Edible vaccines that are heat stable, easy to administer and cheap to produce have the potential to redress many of the production, distribution and delivery limitations faced by traditional vaccines. Published data have shown that the concept of an edible vaccine is valid. Transition from a model system into a practical reality still has some way to go, including managing issues of oral tolerance, genetically modified organism safety, and effective vaccine doses. Successful edible vaccines have the potential to transform health policy and practice in both developed and developing countries.

Administration, Oral↗
PubMed2004

A cell-free biosensor for the detection of transcriptional inducers using firefly luciferase as a reporter.

A cell-free biosensor for the detection of transcription induction by specific small-molecule ligands is presented. As model systems, tetracycline and mercury-inducible promoters were used containing firefly luciferase as reporter gene. Escherichia coli S30 extract was prepared and used for coupled transcription-translation reactions. By using purified Tet repressor and MerR regulatory proteins, we could study repressor-operator interactions for optimizing the relative concentrations of each component. Previously, detection of tetracycline and mercury using similar transcriptional regulation in whole living cells has been carried out. As compared to whole-cell biosensors, our results showed better sensitivity for the detection of tetracycline and the toxic effect of mercury was avoided in the cell-free system. Also, as the system omits cell cultivation and bacterial membranes as molecule passage inhibitors, it is possible to carry out assays in much shorter times and without the use of genetically modified organisms.

Animals↗
PubMed2005

Event specific qualitative and quantitative polymerase chain reaction detection of genetically modified MON863 maize based on the 5'-transgene integration sequence.

Because of the genetically modified organisms (GMOs) labeling policies issued in many countries and areas, polymerase chain reaction (PCR) methods were developed for the execution of GMO labeling policies, such as screening, gene specific, construct specific, and event specific PCR detection methods, which have become a mainstay of GMOs detection. The event specific PCR detection method is the primary trend in GMOs detection because of its high specificity based on the flanking sequence of the exogenous integrant. This genetically modified maize, MON863, contains a Cry3Bb1 coding sequence that produces a protein with enhanced insecticidal activity against the coleopteran pest, corn rootworm. In this study, the 5'-integration junction sequence between the host plant DNA and the integrated gene construct of the genetically modified maize MON863 was revealed by means of thermal asymmetric interlaced-PCR, and the specific PCR primers and TaqMan probe were designed based upon the revealed 5'-integration junction sequence; the conventional qualitative PCR and quantitative TaqMan real-time PCR detection methods employing these primers and probes were successfully developed. In conventional qualitative PCR assay, the limit of detection (LOD) was 0.1% for MON863 in 100 ng of maize genomic DNA for one reaction. In the quantitative TaqMan real-time PCR assay, the LOD and the limit of quantification were eight and 80 haploid genome copies, respectively. In addition, three mixed maize samples with known MON863 contents were detected using the established real-time PCR systems, and the ideal results indicated that the established event specific real-time PCR detection systems were reliable, sensitive, and accurate.

Animals↗
PubMed2005

Site-specific DNA recombinases as instruments for genomic surgery.

Site-specific DNA recombinases can "cut and paste" DNA. For example, they can promote excision of specific DNA segments or insertion of new DNA segments in specific places. However, natural recombinases act only at their cognate recombination sites, so current applications are limited to genetically modified organisms in which these sites have been introduced into the genome. Transposases also catalyze DNA rearrangements; they promote insertion of specific DNA sequences but at nonspecific locations. Applicability of site-specific recombinases and transposases in experimental genetics, biotechnology, and gene therapy would be much wider if they could be re-engineered so as to act specifically at chosen sequences within an organism's natural genome. This review will discuss progress towards the creation of such "designer" recombinases.

Base Sequence↗
PubMed2002

Genetic analysis of pain mechanisms.

Pain is the major reason for visits to the doctor. It is a complex sensation, with both a sensory and an emotional component. Its detailed regulation at all levels of the central nervous system, from the periphery to the cortex, has hindered our understanding of the neurobiological basis of pain. Furthermore, injury can produce long-lasting changes in pain pathways and chronic pain. The recent use of genetically modified organisms has significantly advanced our comprehension of the molecular and cellular mechanisms underlying pain. In this article we present the current state of knowledge regarding pain transmission, modulation, and plasticity, and some of the contributions made by studies of genetically altered mice. The cellular mechanisms explaining observed phenotypes, the involvement of supraspinal areas, and the plasticity underlying chronic pain are the three areas just beginning to be explored.

Animals↗
PubMed1996

Development of recombinant baculoviruses for insect control.

In this review, we provide an overview of the current status of recombinant baculoviruses, describe the development of genetically engineered baculoviruses for use as rapid-action biological insecticides, and provide more detailed information on one particular set of recombinant viruses. The advantages and disadvantages of recombinant baculovirus insecticides, and the importance of risk-assessment studies of these genetically modified organisms, are reviewed. Finally the importance of sensible regulatory strategies to the success and future prospects of this technology is discussed.

Animals↗
PubMed2001

Agricultural biotechnology in developing countries.

After a slow start many developing countries are now investing in agricultural biotechnology. Although these countries face several constraints, efforts are being made to promote biotechnology that requires high investment with long term returns. A number of donor agencies are providing incentives to stimulate biotechnology in the developing countries. There is however a major debate towards the development of biotechnology, especially genetically modified organisms, in the developing countries and there is a need for them to address biosafety issues and proper monitoring systems. The concern of intellectual property rights is a major issue in the developing countries in order to have access to the technologies that are often owned by multinational corporations in the industrialized countries.

Agriculture↗
PubMed2003

Genes in new environments: genetics and evolution in biological control.

The availability of new genetic technologies has positioned the field of biological control as a test bed for theories in evolutionary biology and for understanding practical aspects of the release of genetically manipulated material. Purposeful introductions of pathogens, parasites, predators and herbivores, when considered as replicated semi-natural field experiments, show the unpredictable nature of biological colonization. The characteristics of organisms and their environments that determine this variation in the establishment and success of biological control can now be explored using genetic tools. Lessons from studies of classical biological control can help inform researchers and policy makers about the risks that are associated with the release of genetically modified organisms, particularly with respect to long-term evolutionary changes.

Animals↗
PubMed1998

Horizontal gene transfer as a biosafety issue: a natural phenomenon of public concern.

The transfer of genetic information between distantly or even unrelated organisms during evolution had been inferred from nucleotide sequence comparisons. These studies provided circumstantial evidence that in rare cases genes had been laterally transmitted amongst organisms of the domains bacteria, archaea and eukarya. Laboratory-based studies confirmed that the gene pools of the various domains of organisms are linked. Amongst the bacterial gene exchange mechanisms transduction, transformation and conjugation, the latter was identified as the mechanism with potentially the broadest host range of transfer. Previously, the issue of horizontal gene transfer has become important in the context of biosafety. Gene transfer studies carried out under more natural conditions such as in model ecosystems or in the environment established that all gene transfer mechanisms worked under these conditions. Moreover, environmental hot-spots were identified where favourable conditions such as nutrient enrichment increased the probability of genetic exchange among bacteria. In particular, the phytosphere was shown to provide conducive conditions for conjugative gene exchange. Concern has been expressed that transfer of recombinant DNA (e.g. antibiotic resistance genes) from genetically modified organisms (GMOs) such as transgenic plants to phytosphere bacteria may occur and thus contribute to the undesirable spread of antibiotic resistance determinants. Studies which were performed to address this issue clearly showed that such a transfer occurs, if at all, at extremely low frequency.

Biological Evolution↗
PubMed2006

A new PCR-CGE (size and color) method for simultaneous detection of genetically modified maize events.

We present a novel multiplex PCR assay for simultaneous detection of multiple transgenic events in maize. Initially, five PCR primers pairs specific to events Bt11, GA21, MON810, and NK603, and Zea mays L. (alcohol dehydrogenase) were included. The event specificity was based on amplification of transgene/plant genome flanking regions, i.e., the same targets as for validated real-time PCR assays. These short and similarly sized amplicons were selected to achieve high and similar amplification efficiency for all targets; however, its unambiguous identification was a technical challenge. We achieved a clear distinction by a novel CGE approach that combined the identification by size and color (CGE-SC). In one single step, all five targets were amplified and specifically labeled with three different fluorescent dyes. The assay was specific and displayed an LOD of 0.1% of each genetically modified organism (GMO). Therefore, it was adequate to fulfill legal thresholds established, e.g., in the European Union. Our CGE-SC based strategy in combination with an adequate labeling design has the potential to simultaneously detect higher numbers of targets. As an example, we present the detection of up to eight targets in a single run. Multiplex PCR-CGE-SC only requires a conventional sequencer device and enables automation and high throughput. In addition, it proved to be transferable to a different laboratory. The number of authorized GMO events is rapidly growing; and the acreage of genetically modified (GM) varieties cultivated and commercialized worldwide is rapidly increasing. In this context, our multiplex PCR-CGE-SC can be suitable for screening GM contents in food.

DNA, Plant↗
PubMed2002

Genetic analysis of the mammalian cell death machinery.

Programmed cell death is used by multicellular organisms to eliminate excess, damaged or harmful cells. This process of cell suicide, defined in morphological terms as apoptosis, is crucial for developmental morphogenesis, tissue homeostasis and defense against pathogens. Over the past decade, our understanding of the genetic basis of the cell death machinery has grown exponentially using genetically modified organisms. In particular, inactivation of genes involved in cell death using homologous recombination in mice has provided an invaluable tool to understand the mechanisms, as well as the structural and functional consequences, of programmed cell death in mammals. This review discusses recent insights into the cellular death program as revealed by these mutant animals.

Animals↗
PubMed1993

Nature in the laboratory--nature as a laboratory. Considerations about the ethics of release experiments.

Field tests with genetically modified organisms go beyond the boundaries of the politically and morally neutralized space that normally surrounds scientific experiments. They enter public areas. As a social process of shaping nature they are political in a fundamental sense. Consequences of this observation concern the legitimacy of decisions and the legitimacy of deciding procedures. The political rights of citizens and their human rights can only be respected if these procedures are democratic. Without a more serious exploration of the specific circumstances of release tests--for example, the precise ecological context, the consequences for the future development of the affected ecosystem, the social consequences, and the possible institutional ways of establishing gene technology in agriculture--we do not really know what we are doing when we release transgenic organisms. Moral judgements today can therefore only be prima facie, not free from shortcomings. As responsible judges we must confess that we are still morally blind.

Containment of Biohazards↗
PubMed1993

Suicidal genetic elements and their use in biological containment of bacteria.

The potential risks of unintentional releases of genetically modified organisms, and the lack of predictable behavior of these in the environment, are the subject of considerable concern. This concern is accentuated in connection with the next phase of gene technology comprising deliberate releases. The possibilities of reducing such potential risks and increasing the predictability of the organisms are discussed for genetically engineered bacteria. Different approaches towards designing disabled strains without seriously reducing their beneficial effects are presented. Principally two types of strain design are discussed: actively contained bacteria based on the introduction of controlled suicide systems, and passively contained strains based on genetic interference with their survival under environmental-stress conditions.

Bacteria↗