Tissue-specific gene expression in sexually immature and mature sea lamprey. Gill (G) and liver (L) tissues from immature males (IM, n = 15) and sexually mature males (SM, N = 15) were examined for each gene. Vertical columns represent mean transcripts/ng of total RNA ± 1 SEM. a) cyp7a1 mRNA, b) cyp27a1 mRNA, c) cyp8b1 mRNA, d) bsep mRNA, e) slc10a1 mRNA, f) slc10a2 mRNA, g) sult2b1 mRNA, h) sult2a1 mRNA, i) hsd3b7 mRNA, j) sult1c1 mRNA standard, k) 40s ribosomal RNA standard. Different lowercase letters indicate statistically significant differences in mRNA abundance across tissues or maturities for each gene (ANOVA and post-hoc Tukey’s HSD; α = 0.05). Notice that the mRNA copy numbers (Y-axis) are expressed as exponents (E) of 10.