Differentiation of early mouse embryonic and teratocarcinoma cells in vitro: plasminogen activator production.

Cultured mouse blastocysts produce plasminogen activator, a protease that converts the zymogen plasminogen into the trypsin-like enzyme, plasmin. We have fractionated the blastocyst and cultured the constituent cell types. Trophoblast outgrowths free of inner cell mass derivatives secrete plasminogen activator during a time period that closely parallels the invasive phase of trophoblast cells in utero.

Plasminogen activator in early embryogenesis: enzyme production by trophoblast and parietal endoderm.

We have surveyed the early stages in the development and differentiation of cultured mouse embryos for plasminogen activator production. This enzyme is first detectable by the sixth equivalent gestation day. Thereafter, cultured blastocysts produce plasminogen activator with a biphasic time course: in the first phase, enzyme secretion rises to a maximum at about the eighth day and then decreases; a second phase, during which more enzyme accumulates, begins somewhat later and continues to at least the fifteenth day.

Studies on the role of plasminogen activator in ovulation. In vitro response of granulosa cells to gonadotropins, cyclic nucleotides, and prostaglandins.

A quantitative method is described for measuring the amount of plasminogen activator produced by rat ovarian granulosa cells following exposure to hormones in vivo or in vitro. The results confirm the previously reported observation (Beers, W. H.

Ovarian plasminogen activator: relationship to ovulation and hormonal regulation.

A technique is described for detecting fibrinolytic activity of single cells in culture. This method was applied to the analysis of rat ovarian granulosa cells. Cells obtained from follicules shortly before ovulation show high levels of fibrinolytic activity.

Fibrin overlay methods for the detection of single transformed cells and colonies of transformed cells.

Fibrin overlay methods are described which can detect the plasminogen activator produced by single transformed cells or small colonies of transformed cells. These methods were applied to malignant cells derived from humans, mice, hamsters, rats, and chicks. The lysis observed was plasminogen dependent.

Kinetic and mechanistic studies on the reaction of melilotate hydroxylase with deuterated melilotate.

Melilotate has been synthesized from melilotate by iodiantion followed by reductive deiodination in the presence of deuterated hydrazine. The deuterated melilotate has been employed in investigations of the reaction mechanism of melilotate hydroxylase. Stopped-flow spectrophotometry has revealed no isotope effect in the formation or decay of the oxygenated intermediate which is observed when reduced melilotate hydroxylase reacts with molecular oxygen.