TIME-DEPENDENT VARIATIONS IN THE ACTIVITY OF A NOVEL OVARY MATURATING NEUROHORMONE FROM THE NERVOUS CORPORA CARDIACA DURING OOGENESIS IN THE LOCUST, LOCUSTA-MIGRATORIA-MIGRATORIOIDES

A molecule, which stimulates ovary maturation, was purified completely from the nervous corpora cardiaca of Locusta migratoria migratorioides using only two steps of liquid chromatography separation. A specific polyclonal immune serum directed against the ovary maturating molecule was obtained. It inhibits oogenesis when injected daily into adult females on and after day 1. Injections of the immune serum during oogenesis were used to investigate the time-dependent variations of the activity of the new gonadotropic neurohormone. The presence of the circulating neurohormone is not required for previtellogenesis or for choriogenesis. In contrast, the neurohormone is essential for vitellogenesis. The gonadotropic activity pattern of the neurohormone is somewhat similar to that of the juvenile hormone. However, the novel neurohormone does not disturb metamorphosis and pigmentation suggesting that it has no allatotropic activity. Moreover, inhibition of vitellogenesis by binding the circulating neurohormone with immune serum cannot be compensated for by the implantation of supplementary corpora allata. Thus, the action of the neurohormone on vitellogenesis is probably not mediated through the corpora allata. The ovary maturating neurohormone appears to be the gonadotropic juvenile hormone independent factor previously reported by one of us.