The temporal pattern of interphase prolongation and nuclear activities during early embryogenesis in teleostei

Temporal relationship between the beginning of the increase of interphase duration, RNA synthesis in the nuclei and morphogenetic function of nuclei have been studied using dimensionless criteria of development duration. Experiments were performed in the trout (Salmo trutta m.fario andSalmo irideus), the whitefish (Coregonus lavaretus), the pike (Esox lucius) and the carp (Cyprinus caprio). In all these species interphase begins to lengthen approximately at the same developmental stages. The onset of morphogenetic nuclear function in the pike and whitefish coincides with the onset of interphase prolongation; in the carp RNA synthesis in the nuclei and morphogenetic nuclear function were revealed by 2τ ₀ earlier than onset of interphase prolongation, and in the trout, by 5 and 13τ ₀ later, respectively. Thus, a temporal disconnection between the onset of interphase prolongation, RNA synthesis in the nuclei and morphogenetic nuclear function was established for the first time. It can be suggested that the character of temporal relationship between these processes depends on the relative quantity of yolk in the eggs.