Fig. 1. Localization of 14-3-3 proteins during cell cycle progression. Wild-type embryos were fixed and stained for DNA and with antibodies to 14-3-3 proteins. Staining with an affinity-purified antibody that is specific to 14-3-3 shows that 14-3-3 is dispersed throughout the embryo in interphase of syncytial cycles (left embryo in A and E). The antigen concentration increased in the nucleus in prophase (embryo on the right in A and E) and persists near chromosomes in metaphase (B,F). The staining intensity decreases in anaphase and telophase, with the remaining signal stretching across the dividing nuclei (D,H). A similar cell cycle profile of staining was seen with a commercial pan-specific antibody to 14-3-3 proteins; only the perichromosomal localization in metaphase is shown here (C,G). During cellular cycles (I-N), 14-3-3-specific antibody detected a similar pattern of localization as in syncytial cycles, but exclusion from the nucleus is more apparent. (I,J) The antigen is cytoplasmic in all cells except those in the midst of M14. Mitotic domains 1,2,5 and 8 are indicated. A single cell in mitotic domain 9 is initiating mitosis and is also indicated (other domains reside in the rest of the embryo). (K-N) The change in localization during M14. The antigen concentrates in the nucleus in prophase (arrowheads in K-M), at which time the nuclear envelope remains (arrowheads show remnant wheat-germ agglutinin (WGA) staining in N). The antigen persists in metaphase (arrow in K-M) when the nuclear envelope is absent (arrow in N). In anaphase and telophase, the antigen disperses (brackets in K-M), with the remaining signal concentrating in the region between the nuclei pair in anaphase (smaller bracket in K-M). A similar profile of localization was also revealed by the commercial pan-specific 14-3-3 antibody (not shown). Bar, 5.5 µm in A-H, 16.5 µm in I,J and 13 µm in K-N.