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

Abstract

Metals play crucial physiological roles, but they can also cause irreparable toxic effects through binding to important cellular biomolecules in aquatic organisms.

Comparison of intracellular trace element distributions in the liver and gills of the invasive freshwater fish species, Prussian carp (Carassius gibelio Bloch, 1782)

“…Van Campenhout reported similar finding for the kidney of common carp (C. carpio), where only 2% of cytosolic Zn was bound to MTs, despite much higher renal than hepatic Zn concentrations. The absence of clear Zn binding to MTs in the gills of Prussian carp was consistent with previous findings on the gills of European and Vardar chub, where the majority of Zn was bound to biomolecules of higher MM (Krasnići et al, 2014(Krasnići et al, , 2018(Krasnići et al, , 2019.…”

“…2-7 were associated to molecular masses of specific metal/nonmetal-binding cytosolic biomolecules (Table 4), using the calibration straight line of the applied chromatographic column (Table 3). As already described in all our previous studies of cytosolic metal/nonmetal distributions characteristic for various fish species, for the purposes of easier discussion we always use the categorization of cytosolic biomolecules in the following four classes, according to their molecular masses (MM) (Table 4) (Dragun et al, 2018b;Krasnići et al, 2013Krasnići et al, , 2014Krasnići et al, , 2018Krasnići et al, , 2019: 1) HMM class -containing the biomolecules of high molecular masses (>100 kDa); 2) MMM class -containing the biomolecules of medium molecular masses (>30-100 kDa); 3) LMM class -containing the biomolecules of low molecular masses (10-30 kDa); and 4) VLMM class -containing the biomolecules of very low molecular masses (<10 kDa). As SEC-HPLC has an inherent drawback of low resolution, providing in most cases no more than 6 to 8 peaks (de la Calle Guntiñas et al, 2002), it is reasonable to expect that many biomolecules will coelute, especially in the complex samples, such as cytosols of fish organs.…”

“…5a,b; Table 4), which encompassed the molecular masses of some well known Fe-containing proteins which could be found in the soluble tissue fraction (e.g., hemoglobin; 64 kDa; Beard et al, 1996). Previous study on Vardar chub confirmed the presence of monomers (15.5 kDa), dimers (31.5 kDa) and trimers (47 kDa) of hemoglobin  and  subunits in MMM Fe-peak in both the gills and the liver (Krasnići et al, 2019), and their predominant presence in the gills is consistent with high blood supply of that organ. In the gills, HMM Fe-peak was almost negligible (Fig.…”

“…Additional analyses of MT fractions from Vardar chub liver and gills by anion-exchange HPLC and MALDI-TOF-MS revealed the presence of two MT isoforms in each organ, MT-I and MT-II; molecular masses of both hepatic isoforms were identical (6.0 kDa), but differed from gill isoforms (4.9 kDa) (Krasnići et al, 2019). This finding, together with confirmation that MT isoforms from the gills, unlike the hepatic ones, did not bind Zn, indicated the possibility of different MT functions in these two organs (Krasnići et al, 2019).…”

“…Goenaga Infante et al, 2002;Van Campenhout et al, 2004), European and Vardar chub (Squalius cephalus and Squalius vardarensis; Krasnići et al, 2013Krasnići et al, , 2014Krasnići et al, , 2018Krasnići et al, , 2019, brown trout (Salmo trutta; Dragun et al, 2018), yellow perch (Perca flavescens; Caron et al, 2018), white sucker (Catostomus commersonii; Urien et al, 2018), and European eel (Anguilla anguilla;Goenaga Infante et al, 2003).…”