Metallicity gradients of the lensed galaxies compared with various other published samples (Rupke et al. 2010b; Vila-Costas & Edmunds 1992; Rich et al. 2012; Considère et al. 2000; MACS J1149: Yuan et al. 2011; MASSIV: Queyrel et al. 2012). All central metallicities are converted to the calibration of Equation (7) except those from Vila-Costas & Edmunds (1992). The plot is divided into interacting (or merging) systems and isolated galaxies. All data points at high redshift are shown as filled color symbols. Interacting galaxies have generally lower metallicities and relatively flat or inverted gradients (≲ − 0.05 dex kpc ⁻¹) compared to isolated galaxies.