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Description:
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The AhR is a ligand -activated transcription factor that mediates the toxic effects of environmental contaminants that include TCDD . Using a TCDD dose -response treatment in MEFs , we observed a super induction of CYP1A1 with newborn calf serum (NCS ) in the presence (10nM /15nM ) of TCDD . In addition to NCS , fetal bovine serum (FBS ) also has the capability to yield a CYP1A1 super induction . These results suggest that components within the sera affect the activity of the AhR and consequent CYP1A1 expression . To pursue this idea , characterization of the serum factors were investigated . The findings indicated that serum factor (s ) in both sera are heat sensitive at 50◦C , withstand removal from charcoal stripping sera and are ¡Ý 10 ,000 kDa in size . Using RT -PCR , we found that NCS factors only , could super induce CYP1A1 at the gene level . Moreover , MEFs are the only cells observed in this study that are susceptible to CYP1A1 super induction . |