Figure 7.

Egg activation modulates P body properties in the early embryo

(A–C and E) Mature oocytes expressing Me31B::GFP.

(A) The addition of activation buffer results in simultaneous dispersion of P bodies and bcd mRNA from condensed (t = 0 min) to diffused state (t = 2 min) (n = 0 mature oocytes). Maximum projection 5 μm.

(B) smFISH of activated oocytes stained for Me31B using a GFP-Booster and bcd shows diffuse P bodies and dispersed distribution of bcd mRNAs. Inset shows a zoomed in version of bcd mRNA and P body distribution (n = 10 activated oocytes). Maximum projection 5 μm.

(C) P bodies in the mature oocyte are larger than those in the early embryo (n = 50 early embryos). Max projection 3 μm.

(D) P body recovery profiles after whole FRAP of P bodies in the mature oocyte and early embryo. Mobile fraction for P bodies in the early embryo is 57% compared with 15% in the mature oocyte (n = 20 mature oocytes, n = 8 early embryos) (mean, standard deviation).

(E) smFISH of early embryos stained for Me31B using a GFP-Booster and bcd shows no co-localization of P bodies and bcd mRNAs. Inset shows a zoomed in version of bcd mRNA and P body distribution (n = 10 early embryos). Maximum projection 5 μm.

(F) P bodies (cyan) distributed throughout the mature Drosophila oocyte adopt an arrested physical state. The assembly, organization, and physical properties of P bodies are regulated by multivalent interactions between structured proteins (green) and intrinsically disordered proteins (IDP, yellow), as well as RNAs (magenta). The loss of these interactions alters the physical state of P bodies. At egg activation, P bodies disperse and release stored RNA for translation. In early embryogenesis, P bodies re-condense but are more dynamic and do not co-localize with RNAs. Created with BioRender.com.

Scale bar, 2 μm (A and C), 5 μm (B, D and E).

See also Figure S4.