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

Abstract

Mercury (Hg) contamination is a global issue due to its anthropogenic release, long-range transport, and deposition in remote areas. In Kejimkujik National Park and National Historic Site, Nova Scotia, Canada, high concentrations of total mercury (THg) were found in tissues of yellow perch (Perca flavescens). The aim of this study was to evaluate a possible relationship between THg concentrations and the morphology of perch liver as a main site of metal storage and toxicity. Yellow perch were sampled from five lakes known to contain fish representing a wide range in Hg concentrations in fall 2013. The ultrastructure of hepatocytes and the distribution of Hg within the liver parenchyma were analyzed by transmission electron microscopy (TEM) and electron energy loss spectrometry (EELS). The relative area of macrophage aggregates (MAs) in the liver was determined using image analysis software and fluorescence microscopy. No relation between general health indicators (Fulton's condition index) and THg was observed. In line with this, TEM examination of the liver ultrastructure revealed no prominent pathologies related to THg accumulation. However, a morphological parameter that appeared to increase with muscle THg was the relative area of MAs in the liver. The hepatic lysosomes appeared to be enlarged in samples with the highest THg concentrations. Interestingly, EELS analysis revealed that the MAs and hepatic lysosomes contained Hg.

Toxicity of organic and inorganic mercury species in differentiated human neurons and human astrocytes

“…Accordingly, Villegas et al detected Hg via electron microscopy deposits in neurosecretory neurons of mice after long term oral exposure to HgC1 2 in drinking water exclusively within lysosomes [39). Additionally, accumulation of Hg in hepatic lysosomes was reported for yellow perch, sampled in a Canadian region known as a biological mercury hotspot (40), and for rainbow trout fed with a MeHg supplemented feed diet for 7 weeks [ 41).…”

An integrated assessment of pollution and biological effects in flounder, mussels and sediment in the southern Baltic Sea coastal area

“…Furthermore, biological effects assessed with the IBR index (it included six parameters in flounder and eight parameters in mussels), presented in the form of star plots, indicated that in flounder, it was not the high EROD activity but the MMA density in liver and spleen that showed the greatest relative degree of response and distinguished the three contaminated sites from the reference site. The utility of MMA as a biomarker of contaminant exposure and/or fish health has been demonstrated in several other studies (Fournie et al 2001;Müller et al 2015;Patiño et al 2003;Schwindt et al 2008). According to Wolke (1992), the functions of MMAs are multiple and complex including immune and inflammatory responses as well as storage and destruction or detoxification of various substances.…”

Molecular and cellular effects of contamination in aquatic ecosystems

“…A further study on metal toxicity was carried out with yellow perch, Perca flavescens, from mercury-contaminated lakes in Canada (Müller et al 2015). The study showed a clear relation between a specific cellular reaction in the liver-the formation of macrophage aggregates-and the level of mercury burdens in the fish.…”

“…behaviour) of the aquatic organisms. Thus, the former view that only apical responses are responsible for changes in population growth and survival has shifted towards the understanding that also subtle toxicant effects can have ecological relevance (Relyea and Hoverman, 2006). This may be particularly relevant for chemicals with specific modes of action (e.g.…”

“…Molecular and cellular tools are instrumental for the detection of sublethal, chronic effects and their relation to ecological alterations (Relyea and Hoverman 2006). As formulated by Boxall et al (2003)) for the case of veterinary medicines, 'despite concentration and effects data indicate that acute environmental impacts are unlikely…, some researchers have raised concerns over …the potential longer -term and subtle effects of these medicines'.…”