Fig. 4

Relative gene expression of eGFP gene in response to Cd²⁺, Zn²⁺, Pb²⁺, and Ni²⁺ treatments. The plots depict the concentrations of Cd²⁺, Zn²⁺, Pb²⁺, and Ni²⁺ in blue, orange, ash, and yellow, respectively. The Y-axis represents the relative gene expression, while the X-axis denotes the metal ion concentration in ppb. Error bars indicate triplicate readings of relative gene expression for each heavy metal treatment. A single asterisk (*) represents a P value less than 0.05 (P < 0.05), indicating statistical significance at the 0.05 level. Double asterisks (**) represent a P value less than 0.01 (P < 0.01), indicating statistical significance at the 0.01 level. Triple asterisks (***) represent a P value less than 0.001 (P < 0.001), indicating statistical significance at the 0.001 level