Andrea Bonisoli Alquati, assistant professor of environmental toxicology, led a team that has identified the genetic mechanism causing physiological changes in Seaside Sparrows (Ammospiza maritima) that are similar to changes in exposed fish. Their results were published online in Science of the Total Environment.
Other studies have reported that tuna and amberjack exposed to oil from the spill developed deformities of the heart and other organs that would be expected to be fatal or at least life-shortening. Other studies have found that cardiotoxicity might have been widespread in animal life exposed to the spill.
“In an earlier paper, we found that the oil didn’t stop at the beach or marshes. The oil made it into the terrestrial food web, probably through the sparrows’ diet,” said Bonisoli Alquati. “In this paper, we found that even though the sparrows were exposed to small amounts of oil through very different mechanisms than fish, that exposure changed the expression of some of their genes in ways that are similar to those observed in other organisms.”
The team’s analysis of the transcriptomic response in the sparrows identified 295 genes differentially expressed between birds exposed to oil and a control group. Many of those genes are involved in liver cell proliferation and regulating metabolism.
One of the main functions of the liver is to detoxify chemicals. The genetic changes discovered regenerate liver cells efficiently and inhibit normal spontaneous cell death. This increases liver size giving the birds a larger number of liver cells to help detoxify your body, he explained.
“Birds exposed to oil also change their metabolism a lot,” Bonisoli Alquati said. “It looks like they are converting lipids and carbohydrates, making them more available. There could be many reasons, but it might be that they are dealing with being sick and cannot feed themselves. They switch the type of fats they are using. They do all these things that seem to indicate there are energetic problems.”
The study’s results provide a molecular mechanism for the long-standing observation of hepatic hypertrophy and altered lipid biosynthesis and transport in birds exposed to crude oil.
With this information, scientists will be able to look for consequences of oil spills among terrestrial organisms, expecting that exposure to oil will cause changes in their use of energy and resources.
Because oil interferes with the same genes in species as different as fish and birds, researchers studying new oil spills will be able to use those genes as alarm systems, looking at their expression as an indication that the organisms are experiencing negative effects.
Bonsoli Alquati focuses his research on physiological and genetic responses to environmental contamination, focusing on landscape-level experimental conditions created by environmental disasters, particularly the nuclear accidents of Chernobyl and Fukushima, and the Deepwater Horizon oil spill. His research program also analyzes emerging contaminants and urban development. His lab is also measuring the physiological response of birds to urbanization-related contaminants in the Santa Monica Mountains and analyzing lead contamination in vultures in Southern California.