Vitellogenesis in Anolis pulchellus: induction of VTG-like protein in liver explants from male and immature lizards.
Vitellogenin (VTG) synthesis has been described as an ideal system to study the hormonal regulation of gene expression. In Xenopus the molecular aspects of this control have been analyzed; however, in other non-mammalian species such as reptiles, very few studies approaching this level have been undertaken. We report on the induction by estradiol-17 beta of VTG-like proteins in liver explants from adult males and immature male and female lizards (A. pulchellus). A concentration of 10(-7) M was optimum for adult males while a higher concentration (10(-6) M) is required for the immature animals. No differences were observed in the hormonal induction in male and female immature animals, suggesting that there are no sexual distinctions in the liver at this stage. The effect of the hormone in male liver appears to be primarily on mRNA synthesis, since increases in 3H-uridine incorporation in total RNA were prevented by addition of 1 microgram/ml of the RNA polymerase II inhibitor alpha-Amanitin; however, rRNA synthesis was also increased as observed by agarose gel analysis. A 48 hr lag period was required for the detection of the intracellular as well as the secreted VTG-like protein. Electrophoretical analysis of the secretory products revealed the induction of a group of phosphoproteins immunologically related to yolk lipovitellin whose molecular weights range from 116,000 to 200,000.
Morales
M H
MH
Biology Department, University of Puerto Rico, Río Piedras 00931.
Osuna
R
R
Sánchez
E
E
D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D046508:Culture Techniques; D004527:Egg Proteins; D015387:Egg Proteins, Dietary / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D004958:Estradiol / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008116:Lizards / Q000254:growth & development / Q000378:metabolism; D008297:Male; D008970:Molecular Weight; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000378:metabolism; D014818:Vitellogenesis / Q000235:genetics / Q000502:physiology*
D000546:Amanitins; D004527:Egg Proteins; D015387:Egg Proteins, Dietary; D004965:Estrogen Antagonists; D012333:RNA, Messenger; D004958:Estradiol; C001549:lipovitellin