Induction of cell DNA replication in G1-specific ts mutants by microinjection of SV40 DNA

Treatment of Xenopus laevis follicles with 50–100 units/ml of human chorionic gonadotropin causes rapid stimulation of [¹⁴C]glucose uptake. Studies with these follicles showed that the stimulation of uptake occurred with a wide range of concentrations of [¹⁴C]glucose or its nonmetabolizable analog [¹⁴C]3-O-methylglucose. Approx. 70% of the glucose taken up in both hormone-treated and control cells becomes incorporated into glycogen within 1 h. The uptake of sugar by these follicles was also stimulated by bovine-luteinizing hormone—but not by folliclestimulating hormone, progesterone or insulin. Human chorionic gonadotropin stimulated sugar uptake by follicles containing medium-sized oocytes (stages 3,4 and 5 according to Dumont) which cannot be induced to undergo meiotic maturation by this hormone. After 4–6 h treatment of fully grown X. laevis follicles with either progesterone or human chorionic gonadotropin, glucose uptake suffers a drastic decrease to below basal levels. This inhibition of uptake is coincident with the breakdown of the germinal vesicle of the oocyte and is clearly related to meiotic maturation, since it is not observed with medium-sized follicles which cannot mature.