Fig. 8. H3meK4 is absent in newly formed wild-type Drosophila pole cells but is present in pole cells depleted for pgc function. Wild-type embryos (0-3 hours) and pgc- embryos (0-3 hours) were fixed and co-immunostained with anti-H3meK4 (red) and anti Vasa (green) antibodies. Nuclear density was estimated using a DNA dye, Hoechst (imaged in blue as seen in A,B). (A) Pre-syncytial wild-type blastoderm embryo probed with both antibodies and Hoechst dye. (A') Same embryo showing very little H3meK4-specific signal either in the soma or in the newly formed pole cells. (B) Similar age embryo compromised for pgc function probed with both antibodies and Hoechst dye showing the presence of K4 signal in the newly formed pole cells. (B') Same embryo. Pole cells stained with H3meK4 specific antibodies marked with an arrow and an arrowhead. (C) Wild-type syncytial blastoderm embryo probed with both antibodies. H3meK4 specific signal appears in the soma but pole cells are still devoid of the signal. (C') Same embryo showing just the H3MeK4 staining. (D) A late syncytial blastoderm embryo compromised for pgc function probed with both the antibodies. H3MeK4 specific staining is reduced in almost all pole cells, except in two slightly internally positioned Vasa-positive cells that still show considerable level of signal (marked with an arrow and an arrowhead). (D') Same embryo showing just H3MeK4-specific signal.