Fig. 4.

Metal induction of an endogenous metallothionein gene ameliorates interspecies differences of MTF-1 activity. a Mouse MTF-1 knockout (Dko7) cells were transfected with mouse and human MTF-1 and transcript levels of the endogenous metallothionein-1 mRNA determined in response to zinc or cadmium load. Transfection efficiency was normalized with a co-transfected reference gene. Besides the standard 0.5 μg of mouse effector plasmid, a lower amount (0.1 μg) was also tested, showing that the concentration of MTF-1 hardly affected metal response (see also Georgiev et al. 2014). The transcript level with the zinc-induced human MTF-1 is set to 100. b Experimental setting as in a but with MTF-1s of human, mouse, shrew and bat. no MTF-1, cells transfected with a reference but no MTF-1 effector gene; nt, no metal treatment