Diverse forms of environmental stress induce Tf1 expression and transposition. (A) Tf1 integration sites generated in a previous study (Feng et al. 2013). For mobility assays, we added an artificial intron in neo (neoAI). White boxes indicate UTR; black boxes, ORF; line, intergenic region. (B) Relative level of Tf1 mRNA over time during exposure to CoCl₂. (C) Tf1 transposition rate after exposure to CoCl₂, ZnCl₂, caffeine, and phthalate. Differences that are significant are indicated as follows: (*) P ≤ 0.05; (**) P ≤ 0.005; (***) P ≤ 0.0005.