Immunochemical studies with prolactin-like fractions of fish pituitaries

Abstract

A series of fractions of frozen pituitaries of the carp, Cyprinus carpio L. and the pollack, Pollachius virens L. have been prepared and the methods of extraction given. Immunochemical cross precipitin reactions have been carried out using rabbit antiovine Prolactin and antiovine growth hormone sera to determine the presence or absence of the corresponding hormones in the piscine pituitary fractions. Antipiscine prolactin sera were also obtained in rabbits using partially purified fractions of the pituitaries of the carp (FCa 719-D) and of the pollack (Fp 802-A) as antigens. It was demonstrated that antibody to piscine Prolactin will precipitate with highly purified ovine Prolactin. Using the amount of antigen at antigen-antibody equivalence zone as a point of comparison with earlier preparations, it has been possible to show that in preparation (Fp 878-A) of piscine prolactinn an approximate fivefold step in purification has been achieved. Although preliminary assays of the piscine prolactins by the freshwater survival test in hypophysectomized Fundulus heteroclitus L. indicate that these piscine pituitary fractions may not be biologically active, the precipitin reaction with antiovine Prolactin serum and fish Prolactin as well as the precipitin reaction between antipiscine Prolactin serum and ovine Prolactin suggests that there might be a common structural relationship between the prolactins of phylogenetically widely diverse origins.