Lead (Pb) remains a significant environmental concern in Australian mining and smelting towns such as Broken Hill and Port Pirie, where over 150 years of continuous mining activity have resulted in persistently elevated Pb levels. Chronic lead exposure can subtly impair fitness and reproduction in wildlife. The House Sparrow (Passer domesticus), introduced to Australia during early European settlement, established a population in Broken Hill that has persisted in a very high-lead environment for over a century. Remarkably, this population maintains normal fitness and reproductive output, suggesting adaptive resilience to Pb exposure. Previous genomic studies have identified potential genetic mechanisms underlying this tolerance. Building on these findings, we are now investigating proteomic pathways that may contribute to this adaptation and act as biomarkers of lead toxicity in blood.
Mass spectrometry-based whole blood proteomics is inherently challenging due to the high abundance of haemoglobin. To overcome this, we optimized the use of Mitra VAMS micro-sampling tips for avian blood proteomics. Our method enables reliable protein identification from as little as 2 µL of whole blood or frozen blood pellets, without compromising data quality, and consistently identifies over 2,000 proteins per sample. Using this optimized protocol, we analyzed 100 samples from two mining towns and a low-exposure control group.
Our results reveal a distinct proteomic response to lead exposure in the Broken Hill population compared to sparrows from other mining regions. These populations have been geographically isolated for more than 100 years, likely leading to independent adaptive trajectories in response to the same environmental stressor. Notably, we observed key proteomic changes associated with lead resistance, including the maintenance of δ-aminolevulinic acid dehydratase (ALAD) expression—an enzyme crucial in lead toxicity—as well as shifts in reactive oxygen species (ROS)-related and metalloprotein expression that may collectively enhance tolerance to Pb-induced oxidative stress.