Investigation of cellular stress response related heat shock proteinhsp70/Hsp70 and multixenobiotic transporterabcb1in Siberian freshwater amphipods upon cadmium exposure

Induction of stress response geneshsp70andabcb1and Hsp70 protein by cadmium chloride (CdCl₂) was explored in amphipod species with different stress adaptation strategies from the Lake Baikal area. Based on lethal concentrations (LC) the sensitivities to CdCl₂were ranked (24 hr LC50 – mg/L CdCl₂):Gammarus lacustris(1.7) <Eulimnogammarus cyaneus(2.9) <E. verrucosus(8.3) <E. vittatus(18.2). Conjugated dienes indicating lipid peroxidation were significantly increased by 5 mg/L CdCl₂(24 hr exposure) only inG. lacustrisandE. cyaneus. Upon treatment with 0.54 – 5.8 mg/L CdCl₂hsp70transcript levels were more increased in the toxicologically more sensitive species. Relating the exposure concentrations to LCx values revealed that across the species the increases ofhsp70transcript levels were comparatively low (up to 2.6-fold) up to LC50; at higher LCx valueshsp70induction was more pronounced (up to a 9.1-fold by 5 mg/L CdCl₂(≙LC70) inE. cyaneus). In contrast,abcb1inductions did not correspond with CdCl₂LCx values across species;abcb1induction was highest (4.7-fold) inE. verrucosusby 5.0 mg/L CdCl₂(≙LC45, 24 hr exposure). Induction of stress gene responses by lethal CdCl₂concentrations indicates that in the amphipods they are rather insensitive.