Mercury (Hg) exposure is widely recognized for its extreme neurotoxicity, presenting risks even to scientists dedicated to studying mercury compounds. The eminent physicist Michael Faraday’s own experience serves as a poignant example, as prolonged exposure to mercury vapors compelled him to cease his groundbreaking research at the age of 49 due to deteriorating health. Another tragic incident involved lab chemist Karen Wetterhahn, whose life was cut short by dimethylmercury poisoning when a small amount escaped from a pipette and came into contact with her latex-gloved hands.
While numerous studies have delved into mercury exposure and its effects, particularly in marine life, the question of whether mercury ions can reach the brains of terrestrial animals has sparked curiosity. Dr. Yulia Pushkar, a distinguished professor of Physics and Astronomy at Purdue University’s College of Science, initially approached this question with skepticism. Since 2008, she has led a brain imaging program at Purdue University, garnering global recognition for her group’s expertise in sample preparation, measurements, and data analysis. Researchers from around the world, including Japan and Australia, seek their collaboration to explore the intricate dynamics of mercury exposure in terrestrial animals, expanding our understanding of the far-reaching consequences of mercury contamination.
Dr. Yulia Pushkar’s research group embarked on a critical mission to investigate mercury (Hg) presence in the brains of mongooses collected from Okinawa Island. To their surprise, brain scans revealed the invasive animals harbored mercury, prompting the research group to refine their scans, achieving a remarkable resolution of a few tens of nanometers. These collaborative findings, shedding light on the intricate details of affected brain cells, were recently published in Environmental Chemistry Letters.
Despite the compelling revelations, the mystery surrounding how mercury enters the mongoose brain remains elusive. Potential sources include the water they consume, ingestion of bird eggs, exposure to minerals, or even inhalation of contaminated air. While the specific pathway remains unclear, the unequivocal presence of mercury in mongoose brains raises serious concerns. This discovery underscores the urgency of further research to unravel the sources and mechanisms of mercury contamination, emphasizing the broader implications for both wildlife and human populations in regions affected by mercury pollution.
Dr. Yulia Pushkar emphasizes the significant toxicity of mercury (Hg) even at low concentrations due to its ability to bind and disrupt the function of essential biomolecules. The efficiency of detoxification processes hinges on factors such as the uptake and binding constants within the detected accumulations. Concerns arise regarding potential leakage from these accumulations if brain cells perish. Currently, there exists no established method to safely dissolve these mercury aggregates from tissue, and reversing Hg poisoning of the neural system remains an uncharted territory.
Pushkar underscores the crucial importance of adopting preventive measures to minimize exposure, especially in chronic scenarios akin to the prolonged exposure experienced by eminent figures like Michael Faraday. As there is no known remedy for reversing neural mercury poisoning, the primary approach is to steer clear of any potential sources of exposure, aligning with a proactive strategy to safeguard against the detrimental impacts of mercury on the neural system.
Dr. Yulia Pushkar initially harbored skepticism about the possibility of detecting mercury (Hg) in the brains of mongoose specimens, considering the typically ultra-low concentrations of neurotoxic elements in such tissues. However, this skepticism was defied when the specimens were subjected to intense X-rays at the Advanced Photon Source at Argonne National Laboratory.
During the three-year study, researchers meticulously scanned brain samples, identifying areas with elevated Hg content. Across five trips to two national synchrotron facilities—Advanced Photon Source at Argonne National Laboratory and NSLS-II at Brookhaven National Laboratory—the team observed that specific brain cells, including those of the choroid plexus (comprising the blood-cerebrospinal fluid barrier) and astrocytes of the subventricular zone, contained Hg-rich puncta ranging in size from approximately 0.5 to 2 microns.
The researchers propose that these cells play a crucial role in filtering mercury from both the blood and brain tissue, storing it with the assistance of another element, Selenium (Se). However, the exact Se-containing biological molecules that bind with Hg remain an area for further investigation and discovery.
Dr. Yulia Pushkar’s research team for this publication included graduate students Pavani Devabathini and Gabriel Bury, along with then-undergraduate student Darrell Fischer, who is currently pursuing studies at Harvard graduate school. The comprehensive collaboration involved data collection and analysis by the entire team, with Devabathini and Fischer leading the analytical efforts. The subsequent phase of writing the publication saw contributions from the entire team.
The discovery made by the team holds significant implications for environmental monitoring in terrestrial animals, offering new tools for tracing mercury (Hg) in brain cells. This research may have broader implications for human health and safety, considering the substantial annual emission of 2,000 metric tons of mercury compounds from human activities. While previous studies mainly focused on marine biota, such as fish and whales, this research highlights the impact on terrestrial species, including mongoose, suggesting potential parallels in how the human brain reacts to mercury via interactions with cells of the choroid plexus and astrocytes. However, the researchers note that the extent to which the human brain possesses sufficient Se-containing biomolecules to bind to mercury remains unknown.
Resources
- ONLINE NEWS Pierce, C. & Purdue University. (2024, January 4). High levels of mercury traced to particular cell types in brains of mammals. Phys.org. [Phys.org]
- JOURNAL Devabathini, P., Fischer, D. T., Luo, Y., Pattammattel, A., Bury, G., Antipova, O., Huang, X., Chu, Y. S., Horai, S., & Pushkar, Y. (2023). High-resolution imaging of Hg/Se aggregates in the brain of small Indian mongoose, a wild terrestrial species: insights into intracellular Hg detoxification. Environmental Chemistry Letters. [Environmental Chemistry Letters]
Cite this page:
APA 7: TWs Editor. (2024, January 5). Mammalian Brain Cells with High Mercury Levels Identified. PerEXP Teamworks. [News Link]
