Figure 2

Expression of Bf-Piwil1 and Bf-Piwil2 during embryonic and early larval development. (A-K) Bf-Piwil1 expression patterns. Embryos in A, B, D, E are in lateral view with the animal side up and vegetal side down; four-cell-stage embryo in C is in vegetal view; embryos and larvae in F-K are in left side view with the anterior to the left. Black arrowheads indicate aggregated maternal Bf-Piwil1 mRNA, while hollow arrowheads indicate zygotic Bf-Piwil1 expression around the blastopore during the gastrula stage. Black arrows indicate the expression of Bf-Piwil1 in the putative PGCs located near the posterior growing zone. Scale bars, 50 μm, can be applied to embryos in the same developmental stage. (L-Q) Colocalization of Bf-Piwil1 and Bf-Vasa mRNAs in one-cell- and two-cell-stage amphioxus embryos. L-N are in vegetal view, and O-Q are in lateral view. White arrowheads indicate Bf-Piwil1 and Bf-Vasa signals. Dashed lines indicate the outline of the embryos. (R-Z) Bf-Piwil2 expression patterns. Embryos in R, S, U, V are in lateral view with the animal side up and vegetal side down; four-cell-stage embryo in T is in vegetal view; embryos and larvae in W-Z are in left side view with the anterior to the left. Hollow arrowheads indicate the zygotic Bf-Piwil2 expression in the dorsal side of the late gastrula and early-neurula-stage embryos. Arrow indicates the expression of Bf-Piwil2 in the posterior part of the larva. Stage abbreviations: B, blastula, 4 hpf; MG, mid-gastrula, 6 hpf; LG, late gastrula, 7 hpf; N0, onset of neurulation, 8.5 hpf; N1, early neurula, 10 hpf; N2, mid-neurula, 15 hpf; L1, early larva, 24 hpf.