Mercury immunotoxicity in the brown watersnake (Nerodia taxispilota): An in vitro study. Issue 2 (20th May 2021)

• Record Type: Journal Article
• Authors: Haskins, David L.; Brown, M. Kyle; Meichner, Kristina; Tuberville, Tracey D.; Gogal, Robert M.
• Is Part Of: Journal of applied toxicology. Volume 42:Issue 2(2022)
• Page Start: 180
• Page End: 189
• Publication Date: 2021-05-20
• Subjects: immunotoxicity -- in vitro -- mercury -- peripheral blood collection -- snake; Toxicology -- Periodicals; Industrial toxicology -- Periodicals; Environmentally induced diseases -- Periodicals; Toxicology -- Periodicals; 615.9005
• DOI: 10.1002/jat.4200
• Languages: English
• ISSNs: 0260-437X

Abstract

Abstract: Mercury (Hg) is a heavy metal that enters the environment through natural and anthropogenic means. Once in the environment, Hg can biomagnify in food webs and is known to cause immunotoxic effects to wildlife. Compared with other vertebrates, knowledge of the reptilian immune system is lacking, especially in snakes. Further, even less is known about the impact of environmental contaminants on snake immunity. This gap in knowledge is largely due to an absence of established immune‐based assays or specific reagents for these species. In this study, brown watersnakes ( Nerodia taxispilota; n = 23) were captured on the Savannah River (Augusta, Georgia, USA), weighed, measured, bled, and released. Peripheral blood leukocytes (24 h old) were enriched and evaluated with an established mammalian in vitro lymphocyte proliferation assay. Enriched leukocytes were then exposed to mercury chloride (HgCl2 ) at 3.75, 37.5, and 75 μM. Total mercury (THg) in whole blood was also quantified. Snake peripheral blood leukocyte enrichment yielded >90% lymphocytes with viabilities averaging >70%. Exposure to HgCl2 resulted in significant dose‐dependent suppression of proliferative responses relative to spontaneous proliferation at 37.5 and 75 μM (both p ≤ 0.01) but not 3.75 μM ( p = 0.99). Mean ± 1 SE concentration of THg in whole blood was 0.127 ± 0.027 mg/kg (wet weight). Based on the in vitro findings with HgCl2, snakes in systems with heavy Hg pollution may be at risk of immunosuppression, but N. taxispilota at the site in this study appear to be at low risk. Abstract : Mercury biomagnifies in food webs and causes immunotoxic effects in wildlife. In this study, leukocytes from wild brown watersnakes were exposed in vitro to mercury chloride (HgCl2 ) at 3.75, 37.5, and 75 μM. Exposure to HgCl2 resulted in suppression of proliferation at 37.5 and 75 μM (both p ≤ 0.01) but not 3.75 μM. Snakes exposed to heavy mercury pollution may be at risk of immunosuppression, but snakes at the site in this study appear to be at low risk.