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PubMed2003

Bioaccumulation of nickel from aqueous solutions by genetically engineered Escherichia coli.

This study constructed a genetically engineered Escherichia coli JM109 which simultaneously expressed nickel transport system and metallothionein to remove and recover Ni(2+) from aqueous solution. Bioaccumulation process was rapid and followed linearized Langmuir isotherm. A more than six-fold increase of Ni(2+) binding capacity was obtained by genetically engineered E. coli cells compared with original host E. coli cells. A pH assay showed genetically engineered E. coli cells accumulated Ni(2+) effectively over a broad range of pH (4-10). The presence of 1000 mg/L Na(+) and Ca(2+), or 50mg/L Cd(2+) or Pb(2+) did not have a significant effect on Ni(2+) bioaccumulation, while Mg(2+), Hg(2+) and Cu(2+) posed a severe adverse influence on Ni(2+) uptake by genetically engineered E. coli. Furthermore, genetically engineered E. coli cells did not require extra nutrients for Ni(2+) bioaccumulation.

Biodegradation, Environmental↗

PubMed1989

Single amino acid contributions to protein retention in cation-exchange chromatography: resolution of genetically engineered subtilisin variants.

Genetically engineered proteins were used to determine the amino acid contributions of surface residues to subtilisin retention in cation-exchange chromatography. Crystallographic data were used to correlate the observed chromatographic behavior with enzymatic structure. Retention times of variants in gradient elution varied by as much as 33% compared to the wild type. The role of both charged and uncharged residues was investigated in isocratic separations and found to significantly influence protein retention in this electrostatically dominant separation method. This study demonstrates the ability of ion-exchange chromatography to discriminate between protein variants differing by a single residue in 275 amino acids.

Amino Acid Sequence↗

PubMed1982

GENESIS, a knowledge-based genetic engineering simulation system for representation of genetic data and experiment planning.

We have built a knowledge-based genetic engineering simulation system-- GENESIS-- capable of representing both domain-specific and general knowledge. Information is stored within a hierarchically-organized framework composed of structures called units. A series of sophisticated editors enables no-computer specialist molecular geneticists to construct a knowledge base through direct interaction with the computer. Three types of knowledge specific to the domain of molecular genetics, MAPS, sequences and RULES are discussed in detail with examples.

Animals↗

PubMed1978

Genetic engineering.

The field of genetic engineering is reviewed with a special emphasis on in vitro DNA recombinant technology. The basic principles of the biochemistry of DNA splicing and of gene transfer are described. An important distinction is made between the insertion and cloning of genes derived from genomic DNA ("natural" genes) and of DNA synthetized in vitro ("synthetic" genes). Cloning of genes synthetized from mRNA has provided the probes necessary for the identification of genomic clones, and recently it has made possible the synthesis of specific mammalian proteins in bacteria.

DNA, Recombinant↗

PubMed1999

Genetically engineered polymers for drug delivery.

Genetic engineering methodology offers the ability to synthesize protein-based polymers with precisely controlled structures. Protein-based polymers synthesized by recombinant techniques have a well-defined monomer composition and sequence, stereochemistry, and a narrow molecular weight distribution. The structure of the polymeric carrier at the molecular level influences its biological disposition and drug release profile. Current methodologies of polymer synthesis (chemical polymerization) result in the production of polymers with heterogeneous molecular weights, and with monomer sequences and compositions defined in terms of statistical distributions. Genetic engineering methodologies can be used to design new polymeric drug carriers with improved properties, such as better-defined biorecognition, pharmacokinetic, biodegradation, and drug release profiles. In this review article the rationale and methodology of polymer synthesis using genetic engineering techniques, the status of such polymers in drug delivery to-date, and the potential of these polymers for the development of new systems in the future are discussed.

Drug Delivery Systems↗

PubMed2001

Antibiotic-free chloroplast genetic engineering - an environmentally friendly approach.

Chloroplast genetic engineering offers several advantages over nuclear genetic engineering, including gene containment and hyperexpression. However, introducing thousands of copies of transgenes into the chloroplast genome amplifies the antibiotic resistance genes. Two recent articles report different and novel strategies to either remove antibiotic resistance genes or select chloroplast transformants without using these genes. This should eliminate their potential transfer to microorganisms or plants and ease public concerns about genetically modified crops.

Aldehyde Oxidoreductases↗

PubMed1993

Natural genetic engineering of the bacterial genome.

The term 'natural genetic engineering' means viewing genetic change as a coordinated cell biological process, the reorganization of discrete genomic modules, resulting in the formation of new DNA structures. Examples of natural genetic engineering continue to accumulate, and the concept can be used to integrate observations which demonstrate the similarity between in vitro genetic engineering and the action of in vivo agents of genetic change.

DNA, Bacterial↗

PubMed1993

Applications of genetic engineering technology in feline medicine.

Genetic engineering technology is a rapidly developing field that has almost unlimited potential for the production of safer and more effective vaccines, therapeutic proteins, and more specific and sensitive diagnostic reagents. Although applications in veterinary medicine of genetically engineered products are presently limited by availability of species-specific reagents, the use of recombinant DNA products is increasing. Because of the recent discovery of FIV and the relevance of FIV as an animal model for the study of human immunodeficiency virus, feline genetic research is gaining in importance. Research using FIV as a human AIDS model ideally will yield many new species-specific feline recombinant DNA products that have important applications in feline medicine and research.

Animals↗

PubMed2000

Field applications of genetically engineered microorganisms for bioremediation processes.

Genetically engineered microorganisms (GEMs) have shown potential for bioremediation applications in soil, groundwater, and activated sludge environments, exhibiting enhanced degradative capabilities encompassing a wide range of chemical contaminants. However, the vast majority of studies pertaining to genetically engineered microbial bioremediation are supported by laboratory-based experimental data. In general, relatively few examples of GEM applications in environmental ecosystems exist. Unfortunately, the only manner in which to fully address the competence of GEMs in bioremediation efforts is through long-term field release studies. It is therefore essential that field studies be performed to acquire the requisite information for determining the overall effectiveness and risks associated with GEM introduction into natural ecosystems.

Biodegradation, Environmental↗

PubMed2000

Commodifying animals: ethical issues in genetic engineering of animals.

The genetic modification of living beings raises special ethical concerns which go beyond general discussion of animal rights or welfare. Although the goals may be similar, biotechnology has accelerated the process of modification of types traditionally carried out by cross-breeding. These changes are discussed in relation to two areas: biomedicine, and animal husbandry. Alternative ethical approaches are reviewed, and it is argued that the teleological thesis underlying virtue ethics has special relevance here. The case for and the case against genetic engineering and patenting of life-forms are examined, and conclusions are drawn which favour regulation, caution and respect for animals and animal species.

Animal Experimentation↗

PubMed2005

Food safety evaluation of crops produced through genetic engineering--how to reduce unintended effects?

Scientists started applying genetic engineering techniques to improve crops two decades ago; about 70 varieties obtained via genetic engineering have been approved to date. Although genetic engineering offers the most precise and controllable genetic modification of crops in entire history of plant improvement, the site of insertion of a desirable gene cannot be predicted during the application of this technology. As a consequence, unintended effects might occur due to activation or silencing of genes, giving rise to allergic reactions or toxicity. Therefore, extensive chemical, biochemical and nutritional analyses are performed on each new genetically engineered variety. Since the unintended effects may be predictable on the basis of what is known about the insertion place of the transgenic DNA, an important aim of plant biotechnology is to define techniques for the insertion of transgene into the predetermined chromosomal position (gene targeting). Although gene targeting cannot be applied routinely in crop plants, given the recent advances, that goal may be reached in the near future.

Consumer Product Safety↗

PubMed1995

Genetic engineering in plants.

Until now most research, and its funding, has been focused on animal and human health care as well as simple microbiological model systems such as Escherichia coli and yeast. Molecular plant studies have generally lagged behind, often simply adapting discoveries from the animal field to plants. Clearly, good health and the efficient tackling of diseases is crucial for the well-being of humans, and good remedies have a high economic value for the pharmaceutical industry. However, one should not forget that plants are an essential component of the large ecosystem that is our planet. They are not only the basic food producers but they are also necessary for a balanced atmosphere (oxygen production) and stable and viable climates. Especially in this period of demographic explosion and growing environmental deterioration, there is a need to rebuild our agricultural systems. Plants also have a wide variety of 'non-food' uses, for instance as energy sources, construction materials, or cosmetics. Last, but not least, they produce a lot of chemicals that can be used as pharmaceuticals. The growing awareness of the importance of plants has coincided with the development of plant molecular biology. Specific features make them ideally suited for gene engineering and genetic studies in general.

Biotechnology↗

PubMed1994

Genotoxicity assessment of aromatic amines and amides in genetically engineered V79 cells.

A genetically engineered V79 cell line expressing rat CYP1A2 and another cell line expressing rat CYP1A2 as well as endogenous acetyltransferase activity, as well as CYP-deficient parental V79 cell lines, were used to assess the genotoxicity of the aromatic amines and amides 2-aminoanthracene, 2-aminofluorene, 2-acetylaminofluorene, 4-acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoline, with chromosomal aberrations and sister chromatid exchanges as the end-points. None of the test compounds showed a clear effect on the frequency of chromosomal aberrations in any cell line used. Sister chromatid exchanges, however, were induced by 2-aminoanthracene, 2-aminofluorene and 2-acetylaminofluorene in the CYP1A2-proficient cells, but not in the CYP1A2-deficient cells. The presence of acetyltransferase activity enhanced the effect of 2-aminoanthracene, 2-aminofluorene and 2-acetylaminofluorene. 4-Acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoline did not induce sister chromatid exchanges in the investigated cell lines. The use of cell lines with defined metabolic capabilities seems to be a valuable tool to study specific metabolic pathways important in the activation of procarcinogens.

2-Acetylaminofluorene↗

PubMed1998

Genetic engineering, welfare, and accountability.

Comments on the implications of genetic engineering for animal welfare. Welfare problems associated with techniques used to achieve genetic changes; Detrimental effects of genetic modifications to welfare; Modification of farm animals for biomedical products. Implications of genetic engineering for animal welfare are changing rapidly and need to be reviewed regularly. They include the welfare problems associated with techniques used to achieve genetic changes, which are similar to problems of other experimental approaches; these should be considered carefully, especially where techniques are used on a routine basis. When it comes to the genetic modifications themselves, some are detrimental to welfare, some are neutral, and some are beneficial; these results include direct effects of the intended change, side effects, and indirect effects. Currently, the two main applications are modification of farm animals for biomedical products--which appears to be largely neutral for welfare--and modification of mice as models for human disease, which results in suffering, often severe suffering. Beneficial applications are rare and still experimental or theoretical. The situation is similar with regard to the use of recombinant hormones and viruses; use of recombinant vaccines has potential for improving welfare, but may raise other ethical problems. Although few, if any, of these concerns are specific to genetic engineering, various factors combine to suggest that particular safeguards are needed in this field. These include the facts that changes can be produced rapidly and repeatedly, and that one of the driving forces behind genetic engineering is commercial exploitation of technology. In general, ethical evaluation still is done on a case-by-case basis, using the limited criteria seen as directly relevant to each case, rather than on a broader framework. There also is little public accountability, whereby the public can have confidence that such evaluation is being carried out properly. Calls for advisory "watchdog" committees to consider ethical questions on the use of animals are endorsed by this article. Furthermore, it is essential for public confidence in the safeguarding of animal welfare that the procedures of such committees should be well-publicized.

Journal Article↗

PubMed2002

Inverse metabolic engineering: a strategy for directed genetic engineering of useful phenotypes.

The classical method of metabolic engineering, identifying a rate-determining step in a pathway and alleviating the bottleneck by enzyme overexpression, has motivated much research but has enjoyed only limited practical success. Intervention of other limiting steps, of counter-balancing regulation, and of unknown coupled pathways often confounds this direct approach. Here the concept of inverse metabolic engineering is codified and its application is illustrated with several examples. Inverse metabolic engineering means the elucidation of a metabolic engineering strategy by: first, identifying, constructing, or calculating a desired phenotype; second, determining the genetic or the particular environmental factors conferring that phenotype; and third, endowing that phenotype on another strain or organism by directed genetic or environmental manipulation. This paradigm has been successfully applied in several contexts, including elimination of growth factor requirements in mammalian cell culture and increasing the energetic efficiency of microaerobic bacterial respiration.

Animals↗

PubMed1993

Survival and impact of genetically engineered Pseudomonas putida harboring mercury resistance gene in aquatic microcosms.

The survival of wild-type and genetically engineered Pseudomonas putida PpY101 that contained a recombinant plasmid pSR134 conferring mercury resistance were monitored in aquatic microcosms. We used lake, river, and spring water samples. The density of genetically engineered and wild-type P. putida decreased rapidly within 5 days (population change rate k -0.87 approximately -1.00 day-1), then moderately after 5 to 28 days (-0.10 approximately -0.14 day-1). The population change rates of genetically engineered and wild-type P. putida were not significantly different. We studied the important factors affecting the survival of genetically engineered and wild-type P. putida introduced in aquatic microcosms. Visible light exerted an adverse effect on the survival of the two strains. The densities of genetically engineered and wild-type P. putida were almost constant until 7 days after inoculation in natural water filtered with a 0.45-micron membrane filter, or treated with cycloheximide to inhibit the growth of protozoa. These results suggested that protozoan predation was one of the most important factors for the survival of two strains. We examined the impact of the addition of genetically engineered and wild-type P. putida on indigenous bacteria and protozoa. Inoculation of genetically engineered or wild-type P. putida had no apparent effect on the density of indigenous bacteria. The density of protozoa increased in microcosms inoculated with genetically engineered or wild-type P. putida at 3 days after inoculation, but after 5 to 21 days, the density of protozoa decreased to the same level as the control microcosms.

Animals↗

PubMed2004

Genetically engineered animals in drug discovery and development: a maturing resource for toxicologic research.

Genetically engineered mice that either over-express a foreign gene (transgenic) or in which the activity of a specific gene has been removed ("knock-out") or replaced ("knock-in") will be used increasingly to investigate molecular mechanisms of disease, to evaluate innovative therapeutic targets, and to screen novel agents for efficacy and/or toxicity. Recent innovations of relevance to toxicologic researchers include the construction of genetically engineered mice with (1) multiple engineered genes, (2) mutations that can be induced at specific sites and times throughout life, and (3) the substitution of human genes for their mouse counterparts ("humanized" mice) to allow in vivo investigation of xenobiotic toxicity. Contemporary applications of genetically engineered mice in toxicology include basic mechanistic research exploiting newly engineered mouse lines as well as applied screening for genotoxicity and carcinogenicity using commercially available animals. Many caveats must be considered when interpreting genetically engineered mice-derived toxicity data, the chief of which will be the extent to which the model's phenotype has been fully characterized, the type and incidence of background lesions for the given mouse strain and engineered gene, and the possibility of misinterpreting the presence or absence of a phenotype due to compensatory physiologic processes that mask the outcome produced by the engineering event. Toxicity data acquired using genetically engineered mice currently supplements and in time likely will supplant those gathered using the present "gold standard" bioassays, as genetically engineered mice typically develop more lesions after a shorter latency period than do age- and strain-matched, wild-type mice.

Animals↗

PubMed1994

Perception of risks and benefits of in vitro fertilization, genetic engineering and biotechnology.

The use of new biotechnology in medicine has become an everyday experience, but many people still express concern about biotechnology. Concerns are evoked particularly by the phrases genetic engineering and in vitro fertilization (IVF), and these concerns persist despite more than a decade of their use in medicine. Mailed nationwide opinion surveys on attitudes to biotechnology were conducted in Japan, among samples of the public (N = 551), high school biology teachers (N = 228), scientists (N = 555) and nurses (N = 301). People do see more benefits coming from science than harm when balanced against the risks. There were especially mixed perceptions of benefit and risk about IVF and genetic engineering, and a relatively high degree of worry compared to other developments of science and technology. A discussion of assisted reproductive technologies and surrogacy in Japan is also made. The opinions of people in Japan were compared to the results of previous surveys conducted in Japan, and international surveys conducted in Australia, China, Europe, New Zealand, U.K. and U.S.A. Japanese have a very high awareness of biotechnology, 97% saying that they had heard of the word. They also have a high level of awareness of IVF and genetic engineering. Genetic engineering was said to be a worthwhile research area for Japan by 76%, while 58% perceived research on IVF as being worthwhile, however 61% were worried about research on IVF or genetic engineering. Japanese expressed more concern about IVF and genetic engineering than New Zealanders. The major reason cited for rejection of genetic manipulation research in Japan and New Zealand was that it was seen as interfering with nature, playing God or as unethical. The emotions concerning these technologies are complex, and we should avoid using simplistic public opinion data as measures of public perceptions. The level of concern expressed by scientists and teachers in Japan suggest that public education "technology promotion campaigns" will not reduce concern about science and technology. Such concern should be valued as discretion that is basic to increasing the bioethical maturity of a society, rather than being feared.

Adult↗