Patterns of Incorporation of [32P]orthophosphate and [3H]acetate into Histones of Rainbow Trout during Early Development

Abstract

Nuclear histones of embryos of rainbow trout (Salmo gairdnerii) were isolated after incubation of cell suspension with [32P]orthophosphate and sodium [3H]acetate. In all stages examined from early blastula to neurula, the major proportion of phosphate incorporated was located in histones IIb1 and I. The major histones into which acetate was incorporated were IIb2 and/or IIIm and I. Peaks of acetate and phosphate do not appear at the same positions on acrylamide gels of doubly labelled histones and thus acetylation and phosphorylation appear to be two different alternative or sequential processes. Tryptic digestion of IIb1 indicates that the main site of phosphate incorporation into IIb1 is similar to that found in trout testis, but it is possible that a difference exists since, after thermolysin digestion, the phosphopeptides obtained are not identical with those reported for trout testis IIb1.