Cytosolic distributions of highly toxic metals Cd and Tl and several essential elements in the liver of brown trout (Salmo trutta L.) analyzed by size exclusion chromatography and inductively coupled plasma mass spectrometry

Abstract

Cytosolic distributions of nonessential metals Cd and Tl and seven essential elements among compounds of different molecular masses were studied in the liver of brown trout (Salmo trutta) from the karstic Krka River in Croatia. Analyses were done by size exclusion high performance liquid chromatography and high resolution inductively coupled plasma mass spectrometry. Common feature of Cd and Tl, as highly toxic elements, was their distribution within only two narrow peaks. The increase of cytosolic Cd concentrations was reflected in marked increase of Cd elution within low molecular mass peak (maximum at ∼15 kDa), presumably containing metallothioneins (MTs), which indicated successful Cd detoxification in brown trout liver under studied exposure conditions. Contrary, the increase of cytosolic Tl concentrations was reflected in marked increase of Tl elution within high molecular mass peak (maximum at 140 kDa), which probably indicated incomplete Tl detoxification. Common feature of the majority of studied essential elements was their distribution within more peaks, often broad and not well resolved, which is consistent with their numerous physiological functions. Among observed associations of essential metals/nonmetal to proteins, the following could be singled out: Cu and Zn association to MTs, Fe association to storage protein ferritin, and Se association to compounds of very low molecular masses (<5 kDa). The obtained results present the first step towards identification of metal-binding compounds in hepatic cytosol of brown trout, and thus a significant contribution to better understanding of metal fate in the liver of that important bioindicator species.

Characterization and identification of selected metal-binding biomolecules from hepatic and gill cytosols of Vardar chub (Squalius vardarensis Karaman, 1928) using various techniques of liquid chromatography and mass spectrometry

“…In our previous work we have implemented offline coupling of SEC-HPLC and high resolution (HR) ICP-MS to determine distributions of several elements (Cd, Co, Cu, Fe, Mn, Mo, Pb, Se, Tl and Zn) among cytosolic biomolecules of the gills and/or liver of three fish species, 4 European chub (Squalius cephalus) [27][28] , Vardar chub (Squalius vardarensis) 29 and brown trout (Salmo trutta) 30 . In our studies, the liver were chosen as a key metabolic and detoxification organ of fish, containing a high amount of various metalloproteins which are characterized by a wide range of molecular masses 7,31 .…”

“…The resolution and sensitivity of SEC-HPLC method is such that it offers a rough separation of studied metal-binding biomolecules, and obtained elution peaks of each studied element generally cover rather wide ranges of molecular masses, which can include several metalloproteins. Furthermore, elution peaks of different metals can partially or completely overlap, thus needing a further separation before any kind of additional analyses [27][28][29][30] .…”

Metal-binding biomolecules in the liver of northern pike (Esox lucius Linnaeus, 1758): The first data for the family Esocidae

“…For the sake of simpler comparison with previously published reports for the liver of several other fish species (Krasnići et al, 2013(Krasnići et al, , 2018Dragun et al, 2018;Krasnići et al, 2019;Dragun et al, 2020), we have applied biomolecule categorization in four groups of molecular masses (MM) (Table 3): 1) HMM, which contains the biomolecules of high molecular masses (>100 kDa); 2) MMM -medium molecular masses (>30-100 kDa); 3) LMM -low molecular masses (10-30 kDa); and 4) VLMM -very low molecular masses (<10 kDa) which refer to peaks outside of the separation range of the column. As the separation method applied in this study has rather limited resolution possibilities, it can be expected that many of metal-binding biomolecules coelute, and, therefore, the obtained chromatographic peaks have possibly reflected the binding of analyzed elements to one or more cytosolic biomolecules (de la Calle Guntiñas et al, 2002;Dragun et al, 2020).…”

“…More systematic approaches, which would provide deeper insight in behaviour of higher number of metals within the organs and cells of various fish species, are not often encountered. In recent years, our research group have initiated a series of investigations on few organs (liver, gills, intestine) of several fish species (European and Vardar chub (Squalius cephalus and Squalius vardarensis; Krasnići et al, 2013Krasnići et al, , 2014Krasnići et al, , 2018Krasnići et al, , 2019, Prussian carp (Carassius gibelio; Dragun et al, 2020;Mijošek et al, 2021), brown trout (Salmo trutta; Dragun et al, 2018)), to describe the distribution of a number of metals among the cytosolic biomolecules of different molecular masses by use of SEC-HPLC and high resolution (HR) ICP-MS. Similar type of studies was so far conducted by only few researchers, and encompassed analyses on fish organs (liver of juvenile yellow perch (Perca flavescens; Caron et al 2018); liver and gonads of white suckers (Catostomus commersonii; Urien et al, 2018)) and on the other aquatic organisms (Perna perna mussels: gills (Hauser-Davis et al, 2021) and muscle and digestive gland (Lavradas et al, 2016); Mytilus galloprovincialis mussels -digestive gland (Strižak et al, 2014); marine crustaceans (Li et al, 2005)).…”

Study on the Ecotoxic Effects of Uranium and Heavy Metal Elements in Soils of a Uranium Mining Area in Northern Guangdong

“…Therefore, Cd, As and U are the main contaminating elements in the soils of our study area and the pattern of change in the degree of contamination and risk level of the tailings ponds (T1 and T2) is consistent with the study by Zhang et al [ 53 ]. Based on the above results, the average concentrations of Cd, As and U far exceeded their background values and all three elements had high concentrations even at low concentrations, with toxicity factors of 30 for Cd and U and 10 for As [ 54 , 55 ].…”