Selectivity of metal bioaccumulation and its relationship with glutathione S-transferase levels in gonadal and gill tissues of Mytilus galloprovincialis exposed to Ni (II), Cu (II) and Cd (II)

• DOI: 10.1007/s12210-016-0564-0
• Publication Date: 2016-09-02T21:12:11Z
• Authors: Marina Piscopo; Marica Ricciardiello; Giancarlo Palumbo; Jacopo Troisi
• Keywords: Bioconcentration; Metallothionein

In order to identify a metal bioaccumulation marker usable in monitoring programs, we analyzed the metal content in Mytilus galloprovincialis gill and gonadal tissues and its relationship with π-gst expression levels after a laboratory exposure for 24 h to individual chlorides of Ni, Cu, 5, 15, 35 µM and Cd 1,5; 5, 10 µM in artificial sea water. Inductively coupled plasma-mass spectrometry showed that metal content increased in both tissues in an exposure dose-dependent fashion except for Ni in gonadal tissues, where a low value at the highest exposure was observed. Metal bioaccumulation was higher in gill than gonadal tissues as was π-gst expression level, measured by RT-qPCR, except for the highest Cu exposure. In the gonadal tissue, Ni induced the highest π-gst increase resulting in 2.5- and 4-fold at 5 and 35 μM, respectively, while only about twofold for some Cu and Cd dose exposure. In gill tissue, instead Cd produced π-gst dose-dependent increase being 2.3- and 9.6-fold at 5 and 10 μM, respectively. Ni and Cu meanwhile produced 12- and 5-fold expression levels only at the highest concentration used. Mytilus galloprovincialis shows also a selectivity to accumulate the investigated metals, since metal concentration reduction in ASW, after exposure, was 96–97 %; 85.1–90 % and 4.5–10 % for Cd, Cu and Ni, respectively. Finally, π-gst expression levels correlated particularly with the amount of bioaccumulated Cd in gill tissue, indicating π-gst as a potential marker, even if not univocally, of significative cadmium bioaccumulation usable in environmental monitoring programs.