Heavy metals, when present at elevated concentrations, can be toxic to humans and wildlife. In particular, lead exposure can act as a stressor to wildlife and cause negative effects on fitness and reproduction in animals. The ability to adapt to the stress caused by the negative effects of pollutants would be beneficial for species living in contaminated environments. However, mechanisms for responding adaptively to environmental contaminants are not fully understood especially in free-living animals.
House sparrows (Passer domesticus) have been model organisms for decades to study adaptive and evolutionary responses to biotic and abiotic factors. Isolated populations of house sparrows in Australian lead mining and smelting towns provide a unique opportunity to study the mechanisms of adaptation to environmental lead contamination. We believe that the long-term lead exposures have induced the stress-adaptive response in sparrows to withstand the elevated lead levels in lead mining towns such as Broken Hill.
In this study, we employed mass spectrometry-based proteomics to uncover the underlying mechanisms of lead toxicity and adaptive responses in sparrows. In a detailed dose-response study, we subjected 120 sparrows from two different locations, Broken Hill and Hunter Valley to 6 weeks of controlled lead dosing. Our preliminary results indicate that sparrows from Broken Hill can withstand high levels of lead compared to free-living birds from the Hunter Valley. We are conducting a large-scale proteomics study of plasma, blood/Red Blood Cells (RBC), the brain, and the liver.
Plasma samples from the sparrows were depleted using perchloric acid and analyzed on Thermo Obitrap Exploris 480, in DIA mode over the 60-minute gradient. A sample-specific library was generated using Fragpipe against P. domesticus database. Data was searched using DIA-NN using the library. An average of 400 unique proteins were identified with a single shot 60-minute gradient. Peptides from liver samples will be analyzed on a TripleTof 6600 instrument in DIA mode. These results will be crucial to understanding the toxicity mechanisms, adaptive response, and biomarkers of lead toxicity.