RESUMEN
In order to determine the direct of aflatoxin B1 on the transcriptional activity in cow liver, RNA polymerase was solubilized from the chromatin and each of the chromatin, eolubilized enzymes, deoxyribonucleoprotein [DNP] and CT-DNA was pre incubated with AFB1 overnight at 4 C before assaying the transcriptional activity. Aflatoxin B1 inhibited the [3H] UMP incorporation in a dose dependent manner and the effect was higher in the Mg2 activated RNA polymerase than the Mn2+ activated form. The inhibitory effect was more pronounced on the solubilized enzyme than the chromatin bound suggesting a direct effect at the enzyme level. On the other hand incubating CT DNA or DNP with aflatoxin reduced the transcriptional capacity with higher level on the Mg2+ activated RNA polymerases. The results suggest that AFB1 inhibits the transcriptional activity in cowliver at both the enzyme and template levels