Exploring Eco-toxicogenomics

The year is 2015 and a scientist is working late into the night to try to determine the cause of death of hundreds of lobsters off the coast of New Brunswick. The scientist wonders: Did toxic chemicals affect the lobsters? If toxic chemicals were the cause, did they target respiratory organs, the brain, the endocrine system or the heart?

Carefully, the scientist extracts RNA1 from all major organs of a poisoned lobster sitting in the test tray on the work bench. He tags the RNA samples with a fluorescent material and a robot adds the samples to hundreds of "DNA microchips". The microchips are quickly analyzed with a scanner. When the results are available, the scientist will be able to compare the RNA "signature" from the poisoned lobster with that from a healthy lobster. The RNA signature will explain the cause of death.

The fishing industry anxiously awaits the scientist's results to determine the cause of the lobster die-offs. The genetic testing method being used allows the scientist to produce results more quickly than traditional toxicity testing methods. For the lobster industry, time is of the essence to preserve the harvesting season. The fishermen's livelihood depends on harvesting enough healthy Atlantic lobster to meet the booming global demand.

Like the fishing industry, regulatory officials are also eagerly anticipating the scientist's results. The results could be key to building a science-based case for regulation or other interventions to control the contaminants of concern and to prevent the harm caused by these contaminants.

A Not So Distant Future

Although currently a fictional story, the scenario just described is one that could become a future reality for Environment Canada (EC) and its many collaborating partners involved in genomics research. The story illustrates an emerging field of study known as eco-toxicogenomics, an area of research that EC scientists are now actively exploring.

Toxicogenomics is broadly defined as the study of how an organism's genetic information responds to toxic substances. Eco-toxicogenomics is the application of toxicogenomics to wild species. Eco-toxicogenomics studies the organism as a way of understanding the effects that contaminants in the environment can have on ecosystems in particular. It is a complicated science in its relative infancy, yet eco-toxicogenomics could provide the next generation tools for toxicity screening and risk assessment processes.

Current Research Underway

Scientists at EC are exploring the use of eco-toxicogenomics to research the effects of a variety of contaminants on soils, sediments, birds and aquatic life. They are also investigating the potential application of eco-toxicogenomics for monitoring the health of ecosystems in Canada. The knowledge resulting from this research may act as part of an "early warning system". It would alert environmental scientists to the first signs of threats to plant and animal species. It would also provide the information needed to help officials make appropriate conservation and potential regulatory decisions.

For example, EC scientists are measuring how certain species respond at the genetic level to exposure to toxic substances. In one such study, EC scientists and their colleagues at McMaster University demonstrated that gulls living near active steel mills show more genetic mutations than gulls living in either urban or rural settings. On-going studies are attempting to determine if the mutations are due to exposure to polycyclic aromatic hydrocarbons (PAHs) or some other environmental contaminant. PAHs and other toxic contaminants are identified as toxic substances under the Canadian Environmental Protection Act, 1999 (CEPA) Schedule 1 - List of Toxic Substances.

Benefits of Eco-toxicogenomics

The cataloguing, analyses and interpretation of data from eco-toxicogenomics research can provide a clearer, more precise picture of an ecosystem's response and susceptibility to chemically-induced diseases and to contaminants. This improved understanding will allow scientists to customize test designs and test methods, targeting them for given chemicals. By focussing resources into targeted tests and risk assessment methodologies, tests and test methods will become more thorough, less costly, and more rapid. Development of new genomics-based approaches will also allow scientists to evaluate the overall effects of exposure of small doses of contaminants in the environment, leading scientists to recognize classes of effects that may result from genetic, cellular, or physiological responses within organisms.

Challenges Ahead

While scientists recognize the many benefits of eco-toxicogenomics, they also acknowledge the challenges they face in developing this emerging technology. Scientists must address the need to develop standardized methodologies for obtaining and validating data. Also, the volume of data generated from genomics-based research is significant and must be managed.

EC scientists are working with their counterparts in other government agencies, academia, and the inteRNAtional scientific community to address these challenges. In the very near future, this technology has the potential to become an important new tool in the environmental scientist's toolbox.

Protecting Canadians and Our Environment

Eco-toxicogenomics tools have the potential to provide a faster, more effective and efficient evaluation of toxic substances and their possible impact on selected ecosystems. Ultimately, the technology will help scientists contribute to the better protection of Canada's endangered and commercially-important wildlife populations. At the same time, research results using this technology can inform preventative strategies to minimize potential risks to the health of Canadians.

¹RNA or Ribonucleic acid is very similar to DNA, the nucleic acid that contains the genetic code for all living organisms. However, RNA differs in important structural details from DNA and it has different functions than DNA. It is the RNA extracted from an organism that is used in eco-toxicogenomics studies to measure which genes are affected after exposure to environmental contaminants.