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. 2017 Dec 14;12(12):e0189779. doi: 10.1371/journal.pone.0189779

Fig 3. Confocal micrographs (optical sections) showing dynamics of Carsonella and Profftella during the embryogenesis of D. citri.

Fig 3

Whole-mount FISH images of embryos. Red (Alexa Fluor 594), green (Alexa Fluor 488), and blue (DAPI) signals indicate Carsonella, Profftella, and the host nuclei, respectively. (A) Blastula-stage embryo collected at 0–6 h post-oviposition. A tightly aggregated ball-like mosaic mass of Carsonella and Profftella can be observed at the posterior pole of the embryo. (B) An embryo at 6–12 h post-oviposition. The symbiont mass was loosening. (C) An embryo at 12–18 h post-oviposition. Carsonella and Profftella can be observed in the central and peripheral parts of the mass, respectively. Host nuclei are observed in the symbiont mass. (D) An embryo18–24 h post-oviposition. Carsonella and Profftella can be observed in the central syncytium and peripheral uninucleate bacteriocytes, respectively. (E) An embryo at 24–30 h post-oviposition. The head of the germ band nears the proto-bacteriome. Uninucleate bacteriocytes harboring Profftella migrate toward the posterior pole. (F) A katatrepsis-stage embryo at 30–36 h post-oviposition. The uninucleate bacteriocytes harboring Profftella assemble at the posterior pole, whereas the syncytium containing Carsonella resides on the anterior side of the mass. (G) An embryo (36–48 h post-oviposition) in the process of dorsal closure. The syncytium harboring Carsonella is divided into uninuclear bacteriocytes and begins to surround the mass of Profftella-containing bacteriocytes. (H) An embryo at 48–60 h post-oviposition. The proto-bacteriome is settled within the embryo. (I) An embryo at 60–72 h post-oviposition. The mass of bacteriocytes harboring Profftella is fused into a syncytium, which is completely surrounded by uninuclear bacteriocytes containing Carsonella. (J) An embryo at 72–84 h post-oviposition. Two wing-like protrusions start to grow from the lateral sides of the bacteriome. (K) Enlarged image of the symbiont mass with host nuclei shown in C. (L) Enlarged image of the cellularized proto-bacteriome shown in D. (M) Enlarged image of the proto-bacteriome shown in H. Profftella-containing bacteriocytes are still uninucleate. (N) Enlarged image of the proto-bacteriome shown in I. Profftella-containing bacteriocytes are fused into a syncytium. Abbreviations: a, abdomen; gb, germ band; h, head; t, thorax; y, yolk. Scale bars: 50 μm for A–J, 10 μm for K–N. Arrows indicate the presumed direction of motion of the embryo.