Serologically Active Groups of Amphibian Embryos

Abstract

ABSTRACT Using the embryos of T. pyrrhogaster, the activity gradients of serologically active surface groups of protein molecules were analysed in buffered saline soluble (S) fractions of early embryonic stages against anti-S-fraction sera. Titrimetric methods were utilized in determination of the relative degree of participation of each group in the antigen-antibody reaction, as evidenced by inhibition of precipitation subsequent to inactivation of specific surface groups. Use was made of the blocking reagents p-chlor omer cur i benzo ate, monoiodoacetamide, cysteine, iodine, tyrosinase, 2,4-dinitrofluorobenzene, phenyl isocyanate, benzoyl chloride, and diazonium compounds in evaluating the reactivity of the sulphydryl, disulphide, phenol, imidazol, and amino groups. In the S-fractions, low activity of SS—SH groups and of the phenol groups is perceptible in the large oocyte; after fertilization the activity of all groups increases rapidly. The curve of SH activity culminates in the blastula; that of SS shows perceptible activity in the morula, wanes in the blastula, and then again rises to a maximum in the early gastrula. The gradient of activity of the phenol groups reaches its peak in the late gastrula stage. The amino and imidazol groups demonstrate maximum activity in the neurula and tail-bud stages of development.