Simultaneous analysis of conformation and transcription of A and B groups of vitellogenin genes in male and female Xenopus during primary and secondary activation by estrogen.

In male Xenopus, primary estradiol administration results in noncoordinate activation in the liver of the A and B groups of vitellogenin genes, both as judged by transcription and DNase I sensitivity in isolated nuclei, B group genes being activated preferentially in the first 20 hr. Secondary induction in males or "primary" induction in females results in a coordinate and equal transcription of these two groups of genes. The elevated transcriptional activity following primary estrogen stimulation returns to low levels rapidly but the high DNase I sensitivity of these genes persists for 2-3 months. A non-coordinate activation of the A and B groups of vitellogenin genes is however re-established in response to a second administration of estradiol 8 months after primary stimulation of male Xenopus.