Figure 4

Expression of ApVas1/ Apvas1 during germ band formation. (A, B, E, F, I, J, M, N) ApVas1 antibody staining; (C, G, K, O) Apvas1 in situ hybridization; ApVas1/Apvas1 stripes: brackets; (D, H, L, P) Schematic illustrations: migration of bacteria and ApVas1/Apvas1-positive cells are indicated with grey arrows and green double arrows, respectively; invaginating blastoderm is marked with bold lines. Anterior of egg chamber is to the left; in (M-P), anterior of the germ band is to the right. (A-D) Blastoderm embryos prior to invagination. (A’) and (B’) are magnifications of insets in (A) and (B), respectively. Increasing number of ApVas1-positive cells was evidenced by the expansion of stripe width (A: 2 rows; B: 3 rows; cell rows: asterisks). (C) Apvas1 mRNA was restricted to the same area as that of ApVas1 expression presented in (B). (E-H) Invagination of the posterior blastoderm. Invagination furrows marked with arrows in (F) and (G) appear more prominent than those in (E). Posterior boundary of the ApVas1/Apvas1 stripe moved to encounter the anterior border of the bacteria. (I-L) Co-migration of bacteria and the ApVas1/Apvas1 stripe into the yolk. Embryos in (I) and (J) belong to the same preparation but are shown at different focal planes: (I), cortex; (J), interior. (I’) and (J’) are magnifications of insets in (I) and (J), respectively. (K) Apvas1 expression. (L) ApVas1/Apvas1 stripe first reaches to the posteriormost end of the egg and then migrate back inside the yolk. After that, they follow the migration of bacteria. (M-P) Immersion of the ApVas1/Apvas1 stripe into the yolk during anatrepsis. (M) Continuous invagination of the posterior blastoderm pushed bacteria and ApVas1 stripes toward the central region of the egg chamber. (O, N) Cells expressing ApVas1/Apvas1 and bacteria were located at the posterior region of the germ band. Abbreviation: b, bacteria; gc, germ cells. Scale bars: 100 μm.