CHEMICAL PROPERTIES AND PHYSIOLOGICAL ACTIONS OF A STARFISH RADIAL NERVE FACTOR AND OVARIAN FACTOR

Incubation of starfish ovarian tissues with radial nerve factor (RNF) results in the appearance of a second biologically active substance (s) (ovarian factor) in the incubation media. Studies were conducted to eluciate the chemical and physiological properties of these two substances. The two substances could be physically separated by gel filtration following elution from columns of Sephadex G-25. The RNF and ovarian factor were both relatively heat stable. RNF but not ovarian factor was inactivated following enzymatic digestion with pronase. The ovarian factor appears to be a small molecular weight, heat stable, non proteinaceous material. The physiological effects of a starfish radial nerve factor (RNF) and the ovarian factor were compared. The actions of these substances were evaluated on the basis of changes in various components and responses in starfish ovarian fragments maintained in vitro. Both RNF and ovarian factor induced shedding of oocytes and a concomitant decrease in ovarian fragment weight. The magnitude of weight decrease was related to the dose of ovarian factor. The extent of oocyte shedding was similar in fragments treated with RNF and the highest doses of ovarian factor. RNF and ovarian factors produce oocyte germinal vesicle breakdown and dispersion of follicular cells from around oocytes within ligated and unligated ovarian fragments. Increased levels of calcium in seawater did not produce any of these effects; however, washing ovarian fragments in calcium-free seawater partially inhibited the action of RNF and ovarian factor. Oocytes matured within ligated ovarian fragments, following exposure to RNF or ovarian factor, and subsequently released, formed polar bodies. Upon addition of sperm, these eggs formed fertilization membranes and developed in a normal manner to gastrula. These experiments demonstrate that the ovarian factor has several biological effects or initiates a series of interrelated events. All biological activities previously attributed only to the RNF are apparently shared by this ovarian factor. © 1969.