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Team:Edinburgh/ethics(biosafety)
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Revision as of 20:02, 19 October 2009
Underlying Philosophy - Biosafety
Personal note
Synthetic biology techniques allow genetic constructs to be inserted into or removed from genomes of genetically engineered microorganisms (GEMs). Introduced genes and regulatory sequences could, theoretically, come from any living source or be synthetically produced.Organisms combining novel traits might be more likely to display novel ecological properties. There is a need to ensure that GEMs do not damage the ecosystems to which they are released (see figure 1).
Figure 1. A summary of the relationships between risk and the ecological properties of genetically modified microorganisms. Taken from [2].
Survival and persistence of GEMs in soil Many factors influence the survival and persistence of microorganisms released into the environment. Some can survive for very long periods in adverse conditions as dormant spores or cysts ; others persist in a viable but non-culturable state without forming such structures. For example, after inoculation of E. coli in soil at 5°C their numbers of declined gradually and reached the detection limit at day 68. At 25°C, the detection limit was reached at day 26 after inoculation. As the vast array of environmental factors influencing GEMs, both biotic (competition and predation) and abiotic (temperature, pH, moisture and adsorption), it is understandable that deriving a competent modeling scheme for GEM survival will be a daunting task.
GEMs which have genes deleted from their genome are generally less risky than those with added genes, and might even be safer than the conventional micro-organisms which they replace. Biological containment can make prolonged persistence of GEMs unlikely by, for example the use of suicide vectors or release into an environment which is only temporarily favourable, such as in the presence of a host crop. GEMs will typically have a decrease level of fitness due to the extra energy demands imposed by introduced foreign DNA, and will therefore unable to compete under real-world conditions.
Monitoring of the survival and spread of GEMs
Monitoring the survival and spread of GEMs introduced into the environment might be difficult or impossible. The use of the lux-based system affords several advantages for monitoring survival and spread processes:
1) bioluminescence is easily detected and requires no substantial input of expensive or obscure survey devices;
2) the production of bioluminescence by our synthetic irganism is completely self-contained, no exogeneous addition of chemicals or co-factors are required;
3) bioluminescence can be monitored directly online, providing a continuous, near real-time profile of the bioremediation process;
4) the use of intact microbes as chemical sensors allows for the monitoring of contaminant bioavailability rather than just contaminant presence. This is in contrast to analytical techniques that may determine contaminant presence in an environmental matrix, but without providing information as to the biological effect of the contaminant. Such data becomes extremely important when attempting to assess detrimental health effects of chemical pollutants on exposed populations, human or otherwise.
Gene transfer
The likelihood and consequences of gene exchange between GEMs and other organisms needs to be assessed, especially when toxin transgenes are involved. Once released GEMs can be expected to evolve in ways that are beneficial to their own survival. here may be strong selection pressure for modifications that allow escape from debilitating effects imposed by biological or physical containment. Generally it makes sense to accept the likely persistence of GEMs or their transgenes after release in the environment and minimize the associated risks accordingly.
Effect of GEMS on ecosystems Because little is known about the effects of species diversity on ecosystem processes the added effects of introducing GEMs will be difficult, if not impossible, to predict. There needs to be more research on the role of biodiversity in maintaining and regulating ecosystem functions, especially those which are life supporting. This will help us to understand the potential for transgenics to have adverse effects on ecosystem structure and function.
Survival and persistence of GEMs in soil Many factors influence the survival and persistence of microorganisms released into the environment. Some can survive for very long periods in adverse conditions as dormant spores or cysts ; others persist in a viable but non-culturable state without forming such structures. For example, after inoculation of E. coli in soil at 5°C their numbers of declined gradually and reached the detection limit at day 68. At 25°C, the detection limit was reached at day 26 after inoculation. As the vast array of environmental factors influencing GEMs, both biotic (competition and predation) and abiotic (temperature, pH, moisture and adsorption), it is understandable that deriving a competent modeling scheme for GEM survival will be a daunting task.
GEMs which have genes deleted from their genome are generally less risky than those with added genes, and might even be safer than the conventional micro-organisms which they replace. Biological containment can make prolonged persistence of GEMs unlikely by, for example the use of suicide vectors or release into an environment which is only temporarily favourable, such as in the presence of a host crop. GEMs will typically have a decrease level of fitness due to the extra energy demands imposed by introduced foreign DNA, and will therefore unable to compete under real-world conditions.
Monitoring of the survival and spread of GEMs
Monitoring the survival and spread of GEMs introduced into the environment might be difficult or impossible. The use of the lux-based system affords several advantages for monitoring survival and spread processes:
1) bioluminescence is easily detected and requires no substantial input of expensive or obscure survey devices;
2) the production of bioluminescence by our synthetic irganism is completely self-contained, no exogeneous addition of chemicals or co-factors are required;
3) bioluminescence can be monitored directly online, providing a continuous, near real-time profile of the bioremediation process;
4) the use of intact microbes as chemical sensors allows for the monitoring of contaminant bioavailability rather than just contaminant presence. This is in contrast to analytical techniques that may determine contaminant presence in an environmental matrix, but without providing information as to the biological effect of the contaminant. Such data becomes extremely important when attempting to assess detrimental health effects of chemical pollutants on exposed populations, human or otherwise.
Gene transfer
The likelihood and consequences of gene exchange between GEMs and other organisms needs to be assessed, especially when toxin transgenes are involved. Once released GEMs can be expected to evolve in ways that are beneficial to their own survival. here may be strong selection pressure for modifications that allow escape from debilitating effects imposed by biological or physical containment. Generally it makes sense to accept the likely persistence of GEMs or their transgenes after release in the environment and minimize the associated risks accordingly.
Effect of GEMS on ecosystems Because little is known about the effects of species diversity on ecosystem processes the added effects of introducing GEMs will be difficult, if not impossible, to predict. There needs to be more research on the role of biodiversity in maintaining and regulating ecosystem functions, especially those which are life supporting. This will help us to understand the potential for transgenics to have adverse effects on ecosystem structure and function.
Each GEM should continue to be assessed on a case-by-case basis. Furthermore, account might need to be taken of genotype x environment interactions if the GEM is destined for widespread release. It should be remembered that where the large scale releases of GEMs are concerned, even events with very low probability might occur with sufficient frequency to cause harm. In appropriate conditions GEMs will reproduce, evolve and transfer genetic material to other organisms in the environment. Mistakes, therefore, might have permanent consequences
Despite of all the hazards associated with releasing novel organisms one must not lose sight of the fact that most GEMs are probably more likely to be beneficial than harmful. Furthermore, taking risks is a part of life we all accept to some extent. When deciding on acceptable levels of risk we should take into account the potential benefits of the GEMs.
Despite of all the hazards associated with releasing novel organisms one must not lose sight of the fact that most GEMs are probably more likely to be beneficial than harmful. Furthermore, taking risks is a part of life we all accept to some extent. When deciding on acceptable levels of risk we should take into account the potential benefits of the GEMs.
Edinburgh University iGEM Team 2009
