Laser Ablation ICP-MS Co-Localization of Mercury and Immune Response in Fish

Abstract

Mercury (Hg) contamination is a global issue with implications for both ecosystem and human health. In this study, we use a new approach to link Hg exposure to health effects in spotted gar (Lepisosteus oculatus) from Caddo Lake (TX/LA). Previous field studies have reported elevated incidences of macrophage centers in liver, kidney, and spleen of fish with high concentrations of Hg. Macrophage centers are aggregates of specialized white blood cells that form as an immune response to tissue damage, and are considered a general biomarker of contaminant toxicity. We found elevated incidences of macrophage centers in liver of spotted gar and used a new technology for ecotoxicology studies, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), to colocalize aggregates and Hg deposits within the tissue architecture. We conclude that Hg compromises the health of spotted gar in our study and, perhaps, other fish exposed to elevated concentrations of Hg.

Evidence of impaired health in yellow perch (Perca flavescens) from a biological mercury hotspot in northeastern north America

“…Recently, Hg and MAs were shown to be colocalized in wild fish liver tissue, directly linking Hg to cellular damage [24]. Analyses using LA ICP-MS of perch from the present study support these findings.…”

“…Analyses using LA ICP-MS of perch from the present study support these findings. Although Hg accumulation in perch MAs was generally lower than that observed in spotted gar by Barst et al [24], 94% of perch MAs contained higher Hg isotope counts than adjacent hepatocytes. This Hg accumulation within liver MAs, in addition to the positive relationships between the prevalence of liver MAs and tissue Hg concentrations, strengthens our hypothesis that Hg exposure results in an increased occurrence of MAs in these perch.…”

“…The distribution of mercury in yellow perch liver sections was examined using laser ablation inductively coupled-mass spectrometry (LA ICP-MS) as described by Barst et al [24]. Briefly, an uncoverslipped microscope slide, with Prussian Blue-stained liver tissue sections (40-mm thick; processed as described above), was placed into the chamber of a 213-nm Nd:YAG laser ablation source (New Wave Research).…”

“…In wild fish, positive relationships existed between the occurrence of liver or kidney MAs and the muscle (THg) of northern pike ($0.21-0.82 mg g À1 wet wt in muscle) [8], of liver MAs and liver or muscle (THg) of spotted gar Table 4. Least squares linear regression relationships between the health variables liver somatic index (LSI) and condition (log 10 transformed) and tissue Hg concentrations (mg g À1 wet wt; log 10 transformed) in female perch of different groups ( 10 cm, > 10 cm, and all lengths) ($0.01-1.1 mg g À1 wet wt in muscle) [24], and of spleen MAs and the (THg) in whole brook trout ($0.03-0.25 mg g À1 wet wt in whole body) independent of age [15]. Our findings suggest that Hg exposure may be causing increased tissue damage in these perch.…”

Morphological alterations in the liver of yellow perch (Perca flavescens) from a biological mercury hotspot

“…Batchelar et al (2013) concluded that the enhanced presence of MAs in tissues of yellow perch from KNPNHS is suggestive of a negative impact of Hg at the cellular level. The positive relationship between the frequency of MAs and tissue Hg concentrations has also been reported for other wild fish species (Barst et al 2011;Meinelt et al 1997;Schwindt et al 2008). Furthermore, laser ablation and inductively coupled plasma mass spectrometry showed that Hg and MAs were co-localized in hepatic tissue and that Hg accumulated in higher amounts in MAs than in the surrounding liver parenchyma (Barst et al 2011;Batchelar et al 2013).…”