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PubMed2000

The ultraviolet environment of Mars: biological implications past, present, and future.

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations.

Atmosphere↗
PubMed2003

Vegetative covers for waste containment.

Disposal of municipal and hazardous waste in the United States is primarily accomplished by containment in lined and capped landfills. Evapotranspiration cover systems offer an alternative to conventional landfill cap systems. These covers work on completely different principles than traditional covers do, and that difference may slow understanding and acceptance by site owners, regulators, and stakeholders. This chapter provides an introduction to this alternative technique and explains some of the common concerns regarding its implementation.

Biodegradation, Environmental↗
PubMed1988

Environmental concerns associated with the design of genetic engineering facilities.

Recombinant DNA technology is being used to produce a wide spectrum of products, such as vaccines, interferon, insulin, and growth hormones. In the design of facilities employing this technology, critical consideration must be given to the protection of the environment, both in the prevention of releases of recombinant DNA organisms into the environment and in the treatment of wastes originating from the production facilities. The design requirements for containment of large-scale systems are complex and require detailed analysis to insure that the containment system can handle both the normal and emergency releases of recombinant DNA organisms. This must include the prevention of releases through either liquid discharges or air emissions. The "killing" method used in the process for either the cells (extracellular product) or the broth (intracellular product) is an important step and can have significant implications in downstream treatment of wastewaters. Since fermentation is the primary process used in the production of recombinant DNA products, wastewater characteristics from this area of the process are basically similar to those of other fermentation processes. They differ, however, because of the "killing" step in the process, which can introduce compounds not normally found in fermentation wastewaters. This can complicate the treatment process by requiring additional treatment operations. Characteristics of wastewaters from other areas of the process can be very diverse, and no general characterization can be made. Techniques for recovery and purification can vary from product to product or even from plant to plant, making characterization difficult. It is important, therefore, that each process be examined in detail so that waste characterization is meaningful and useful in the design of treatment facilities. Because of the complex nature of the processes involved in the production of recombinant DNA products, wastewater treatment can also become a very complex problem. Systems to treat these wastewaters can include many diverse unit operations, from pretreatment of selected streams to tertiary treatment of the combined streams to meet stringent effluent criteria. While biological treatment is almost always applicable, waste loads are very high, and multiple-stage systems could be required. Early and ongoing interface between the process development scientists and engineers and the environmental disciplines allows for the early recognition of potential environmental problems. With early recognition, many of these problems can be economically and efficiently addressed in the design of the facility.(ABSTRACT TRUNCATED AT 400 WORDS)

Containment of Biohazards↗
PubMed1992

An expression vector system providing plasmid stability and conditional suicide of plasmid-containing cells.

A cloning vector system was constructed on the basis of the pBR322 derivative pEG1 by introducing the whole parB locus of plasmid R1 cloned behind the promoter of the alkaline phosphatase gene (phoA) of Escherichia coli. The parB locus in combination with the phoA promoter ensures both (i) plasmid stabilization due to the post-segregational killing of plasmid-free cells during growth and (ii) killing of the cells induced by the potential environmental signal phosphate limitation. This vector, therefore, appears to be a model system for increasing the stability of recombinant plasmids and for decreasing the potential risks in the application of recombinant bacteria in industrial fermentations.

Alkaline Phosphatase↗
PubMed1995

Escherichia coli K12 relA strains as safe hosts for expression of recombinant DNA.

Most Escherichia coli K12 strains survive for a relatively long time outside the laboratory. Under the same conditions the isoallelic E. coli K12 relA mutants die faster because they lack the stringent response. The killing rate is increased by using a plasmid-encoded suicide system consisting of the phage T7 lysozyme gene driven by the E. coli alkaline phosphatase gene promoter (phoA). Cells containing this system were rapidly and effectively killed as soon as phosphate was made limiting. The combination of the chromosomal relA mutation and a conditional suicide system of this type provides an effective means of biological containment for recombinant E. coli strains.

Alkaline Phosphatase↗
PubMed1992

Safe biotechnology (4). Recommendations for safety levels for biotechnological operations with microorganisms that cause diseases in plants.

The Working Party on Safety in Biotechnology of the European Federation of Biotechnology has proposed a classification of microorganisms that cause diseases in plants. In this paper appropriate safety levels are proposed for these classes of microorganisms in order to ensure that research, development and industrial fermentation work with plant pathogens will limit the risk of outbreaks of diseases in crops that could result from work with such microorganisms when they are cultivated in laboratories, glasshouses and biotechnology installations.

Containment of Biohazards↗
PubMed1993

Safe biotechnology (5). Recommendations for safe work with animal and human cell cultures concerning potential human pathogens.

The benefits of using animal or human cell cultures have been clearly demonstrated in diagnostic and therapeutic research and in their application for manufacturing. Cell cultures serve as a tools for the production of vaccines, receptors, enzymes, monoclonal antibodies and recombinant DNA-derived proteins. They represent an integral part of drug development for which corresponding facilities, equipment and manufacturing processes are required. Although the cells themselves offer no particular risk to workers in laboratories and production areas or to the environment, the cell cultures may be contaminated with viruses, mycoplasma, bacteria, yeast and fungi or might contain endogenous viruses. The containment level for animal and human cells is therefore determined by the risk class of these agents. The history of animal and human cell cultures has proved that they can be handled safely. The recommendations in this publication concern the safe handling of cell cultures (tissue explants, primary cell cultures) and permanent cell lines of animal and human origin. A classification system of safety precautions has been elaborated according to the potential for contamination with the pathogenic agents involved.

Animal Population Groups↗
PubMed1993

Biosafety investigations in an r-DNA production plant.

Employees of a biotechnological production plant for recombinant interferon alpha-2a have been participating in a 1-year study on occupational hygiene and the resulting biosafety aspects. Most of the employees have been employed in the plant for more than 6 years. Weekly stool samples were analysed for tetracycline (used as selection marker)-resistant coliforms as well as for rDNA (IFN gene) (interferon gene) and for the production organism. Various analytical methods, including the polymerase chain reaction, were applied to show that neither rDNA nor the production organism could be found in any of the stool samples and that there was no change or trend in the gut flora with respect to tetracycline resistance. In addition it could be shown that the tetracycline-resistance gene, as well as the rDNA, are completely inactivated in the course of the production process and thus no further recombination can take place. Blood samples were taken to show that none of the employees had anti-product antibodies.

Adult↗
PubMed1981

The application of DNA recombinant technology to the analysis of the human genome and genetic disease.

Recombinant DNA technology permits the isolation of libraries of DNA sequences corresponding to either the whole genome of an individual or the expressed sequences of a given cell type. Gene-specific probes isolated from these libraries may be used for the identification of DNA sequences in the genome necessary for normal gene function and for the study of the consequences of mutations and rearrangements in these sequences which give rise to the clinical symptoms in genetic disease. DNA sequence polymorphisms can be used to construct a genetic linkage map of the entire human genome. This allows the development of antenatal diagnoses for monogenic diseases even in the absence of an understanding of the biochemical defect.

Base Sequence↗
PubMed1996

Characterization of two bioluminescent Rhizobium meliloti strains constructed for field releases.

The deliberate release of genetically engineered microorganisms requires a thorough characterization of the microbes in question. For the two bioluminescent Rhizobium meliloti strains, L1 and L33 [Selbitschka et al. (1992) Mol Ecol 1:9-19; Selbitschka et al. (1995) FEMS Microbiol Ecol 16:223-232], designated for field release, the sites of genetic modifications in the chromosomes were sequenced from amplified genomic DNA. This indicated no unexpected alterations in the nucleotide sequence. The bioluminescent phenotype was stably inherited over more than 100 generations in liquid cultures. The presence of the luciferase gene in both strains did not have secondary effects on a variety of metabolic pathways as assessed by the Biolog GN system. A specific polymerase chain reaction amplification, based on the chromosomal insertion site of the luc cassette, allowed the discrimination between the two strains and thus simplifies monitoring. The RecA-deficient strain L1 showed a strongly (more than 90%) reduced ability to nodulate alfalfa in competition with its parent strain R. meliloti 2011 and its RecA+ counterpart L33.

Bacterial Proteins↗
PubMed1981

[Prospects and limitations of genetic engineering].

Examples for genetic engineering are the transfer of nuclei between cells of higher animals and the introduction of heterologous DNA into bacteria by means of plasmids. The former approach will help to establish new ways in animal breeding, the latter provides bacterial cells that produce proteins of medical importance. The moral justification of related studies in man is still open, but the possible risks of gene technology can be coped with by adhering to proper safety regulations.

Animals↗
PubMed1993

Relationship between safety data and biocontainment design in the environmental assessment of fermentation organisms--an FDA perspective.

The Center for Veterinary Medicine requires strain/construct-specific data for recombinant fermentation organisms used in the production of animal drugs and feed additives. Fermentation plant biocontainment schemes are chosen based, in part, upon the ability of the organism to survive and persist in the environment and to transfer genetic information to indigenous organisms. Survival and persistence study methods may include one of the following ecosystems: activated sludge, mammalian gut, soil or river water. Gene transfer protocols can be incorporated into a persistence study. These studies are designed to show that the recombinant construct behaves similarly to the host in a representative ecosystem where the organism could be introduced inadvertently. The studies need to provide repeatable results and reflect current state-of-art design and methods. Data verification is conducted by FDA investigators during Good Laboratory Practice inspections. Biocontainment guidelines, such as those developed by the NIH Recombinant DNA Advisory Committee, set general biocontainment goals for large groupings of recombinant organisms. The FDA, as required under the National Environmental Policy Act, must base its decision making on verifiable scientific data specific to each application. Therefore, in addition to using these guidelines as benchmarks, sponsors are required to submit strain/construct-specific data to support the selection of an appropriate biocontainment level. Once additional well-controlled studies for a variety of constructs are available, broader generalizations as to biocontainment may be drawn.

Containment of Biohazards↗
PubMed1993

Biocontainment design considerations for biopharmaceutical facilities.

This article highlights biocontainment design considerations for biopharmaceutical manufacturing facilities. The major focus of this report is on industry's use and interpretation of the regulations with specific design recommendations for a Biosafety Level 2--Large-Scale physical containment level as described by the National Institutes of Health Guidelines.

Accidents, Occupational↗