Canadian biologists have developed a device to quickly identify genetic changes induced by oil spills or other chemical exposures in wildlife in the Far North, a valuable tool for responding to environmental disasters.
The Carleton University and Environment and Climate Change Canada team spent several years building and perfecting the device called the ToxChip.
This is a small plate that allows the laboratory to measure the expression of around thirty genes, in this case in seabirds, which are associated with chemical upheavals caused by contamination in the ambient environment. .
It allows a gain in efficiency and offers more specificity compared to traditional detection methods, because it can be adapted to the species under study and the type of contaminant in the natural environment, say the researchers.
Populations at risk during spills
With increased shipping traffic expected in the Canadian Arctic and increased oil and gas exploration, the risks of petroleum product spills are increasing, the researchers note, in a recent study. Already, Arctic freight transport has tripled in the past 25 years, with receding ice allowing for a longer shipping season.
In this context, it is important to be able to monitor and intervene with endangered animals in the event of contamination of the natural environment. Especially since communities in the Arctic live from hunting, fishing or the tourist industry and can themselves be exposed to contaminants through the food chain.
The team led by Jennifer Provencher of Environment Canada chose two species of seabirds, the gBrunnich’s guillemot and black guillemot, to test his device.
Seabirds are good indicators of contamination of the natural environment because they are quite high in the food chain and accumulate chemical compounds in their bodies. These compounds are particularly visible in the liver in the days following exposure, as this organ detoxifies blood from the body, says Yasmeen Zahaby, a master’s student in biology at Carleton University. The compounds then accumulate in the fatty tissues of the bird.
Polycyclic aromatic compounds are the main contaminants found in petroleum products. In particular, they cause cancer in birds when they are ingested. Seabirds that become contaminated through food or that become coated in oil during a spill can no longer move properly and reproduce. Entire colonies can thus be threatened, explain the researchers.
Nunavut Seabirds
Biologists traveled to Akpait National Wildlife Area and Qaqulluit Preserve, off the east coast of Baffin Island, Nunavut, to collect liver samples from around 30 individuals of each species , in order to establish a reference for a healthy, and therefore uncontaminated, population. When contamination (spill or otherwise) occurs, researchers will therefore have a point of comparison.
Yasmeen Zahaby explains that the liver samples from the birds being studied are analyzed quickly in the laboratory. We measure, first, the chemical compounds present in the liver tissues, and, then, the expression levels of the genes of interest which react to the contamination (these can be genes involved in metabolism, in the immune system or in DNA repair, for example).
In this way it can be determined how and to what degree the birds have been affected.
“Traditional tests were developed for laboratory animals, such as chickens. However, chickens have different tolerance levels and react differently to chemicals compared to wild species. We mightn’t make valid comparisons,” says Ms. Zahaby. This is why we had to develop a way of dealing with wild animals.
“The other advantage is the chemical specificity. Traditional testing can only be done on one chemical at a time, but most contaminants, like petroleum, are mixtures of hundreds of different chemicals. So this tool allows us to see the effect of contaminants as they are in the real world,” she continues.
“This tool is also cheaper to use, gives results in less time and the process requires far fewer animals. »
The ToxChip can be adapted to detect the effects of a forest fire, plastic pollution or pesticides, and this on different animal species, specify the researchers, which opens up the field of possibilities.
“I am currently working on the development of a Toxchip for the common eider, a species of duck found across Canada,” says Ms. Zahaby. This will allow us to examine the effect of chemicals not only in the Arctic, but wherever this species is found. »
