Figure 1

The inhibitory effects of TCDD on the vitellogenin mRNA levels. After 48 hrs of culture the fish hepatocytes were left untreated or were treated with a fixed concentration of 17β-estradiol (E2) or E2 and increasing concentrations of TCDD. Following a 12-h treatment period, total cellular RNA was isolated. Total RNA (20 μg per lane) was electrophoresed through a formaldehyde-containing agarose gel, transferred to a nylon membrane and sequentially hybridized to [α-³²P]dCTP labelled cDNAs specific for VTG (VTG) and cytochrome P4501A (CYP1A). The top panel (A) shows the VTG gene expression, the panel in the middle (B) shows the expression of the CYP1A gene and bottom panel (C) displays the ethidium bromide staining of the gel to demonstrate equal loading of the samples. The arrows indicate the position of 28S and 18S ribosomal RNAs. The numbers correspond to the kind of treatment of each sample as follows: #1: Control sample (cells treated with DMSO); #2: Cells treated with 10 nM E2; #3: Cells treated with E2 + 1 pM TCDD; #4: Cells treated with E2 + 10 pM TCDD; #5: Cells treated with E2 + 100 pM TCDD; #6: Cells treated with E2 + 1 nM TCDD; #7: Cells treated with E2 + 10 nM TCDD; #8: Cells treated with E2 + 10 nM TCDD + 1 μM α-NF; #9: Cells treated with E2 + 1 μM tamoxifen.