Fig. 4.

Effects of triiodothyronine (T3) exposure on the expression of sex steroid-related genes in Silurana tropicalis premetamorphic tadpoles. Silurana tropicalis (NF 52–54) were exposed to T3 (0, 0.5, 5, 50 nm) for 48 h. Effects of T3 on eralpha and erbeta (a), cyp19 mRNA and activity (b), srd5alpha1 and srd5alpha2 (c) and ar (d) are presented. Gene expression data (y-axis on the left) are presented as the fold changes relative to control and are normalised to RNA content. Enzyme activity (y-axis on the right; b) is expressed in fmol/h normalised to protein content. Bars represent the mean ± SEM. Asterisks represent significant differences in gene expression levels from the control group (n = 8 pools; *P<0.05; **P<0.01; ***P<0.001). Significant differences in enzyme activity levels are indicated by delta (δ; n = 5; P<0.01) relative to the control group. Note that the scales of the y-axis vary between genes.