1. The Adult Body Plan of Indirect Developing Hemichordates Develops by Adding a Hox- Patterned Trunk to an Anterior Larval Territory 
Paul Gonzalez, Kevin R. Uhlinger, Christopher J. Lowe 
Current Biology 
Volume 27, Issue 1, Pages (January 2017)
DOI: /j.cub
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2. Figure 1
Similar Adult Body Patterning of S. kowalevskii and S. californicum despite Early Life History Differences
(A) Adult Saccoglossus kowalevskii enteropneust worm.
(B) Post gastrula embryo showing posterior telotroch.
(C) Diagram of the life cycle of the direct developing S. kowalevskii.
(D) Adult specimen of Schizocardium californicum.
(E) Planktotrophic, tornaria mid-way through larval development with a complex larval morphology.
(F) Diagram of the complex life cycle of the indirect developing S. californicum.
(G) Whole-mount in situ hybridizations of transcription factors with conserved AP-patterning roles in the post-metamorphic juvenile S. californicum. Dorsal view is shown unless otherwise indicated. Anterior is top left, and posterior is bottom right. Endodermal labeling for irx (G8) is specific to the gill slits. Mesodermal labeling in the protocoel for hox1 (G13) and hox11/13a (G19) is background. Scale bar, 1 mm. c, collar; gs, sill slits; p, proboscis; t, trunk; tt, telotroch; vv, ventral view.
(H) Summary diagram of the main expression domains of transcription factors in juveniles. Black lines represent the anterior and posterior boundaries of expression. Genes that pattern the proboscis and collar are represented in blue, genes that pattern the anterior and mid-trunk are in yellow, and genes that define the posterior trunk are in red.
See also Figures S1, S2, and S4 and Table S1.
Current Biology  , 87-95DOI: ( /j.cub )
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3. Figure 2
The Ectoderm of the Developing Tornaria Larva of S. californicum Has an Anterior Identity
(A) The qPCR expression profiles of 26 transcription factors across eight developmental stages, diagrammed below the graphs, spanning early development to post-metamorphosis. While all proboscis- and collar-patterning genes are activated during early larval development (1 and 2), expression of most trunk-patterning genes is delayed until the late tornaria stage (3 and 4).
(B and C) Whole-mount in situ hybridization of transcription factors in the gastrula stage (21 hr post fertilization) (B) and hatched gastrula stage (42 hr post fertilization) (C) embryos of S. californicum. Embryos are shown with anterior top left and posterior bottom right in side view unless otherwise specified and presented as cleared optical sections through the middle of the embryo. The summary diagrams at the left of the in situ panels show the expression of anterior genes (blue) and far posterior genes (red). Black lines represent the anterior and posterior boundaries of expression. At hatching, the embryo of S. californicum is transcriptionally similar to the proboscis and collar of the adult (blue), directly abutting a short domain that expresses markers of the posterior tip of the trunk (red). Scale bar, 100 μm. a, archenteron; ao, presumptive apical organ; b, blastopore; dv, dorsal view; ec, ectoderm; me, mesendoderm; pd, protocoel duct; pm, presumptive mesoderm; pp, protocoel pore.
See also Figures S2 and S3 and Table S1.
Current Biology  , 87-95DOI: ( /j.cub )
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4. Figure 3
A Hox-Expressing Trunk Domain Is Added to the Larval AP Axis prior to Metamorphosis
(A) Whole-mount in situ hybridization of transcription factors in the early tornaria (3 days post fertilization) of S. californicum. Larvae 1–17 are shown as cleared optical sections in side view unless otherwise mentioned, with anterior to the top left and posterior to the bottom right each panel. The summary diagram to the left of the in situ panels shows the early tornaria larva is transcriptionally similar to the proboscis and collar of the adult (blue), directly abutting a short domain that expresses markers of the posterior tip of the trunk (red). Black lines represent the anterior and posterior boundaries of expression. Scale bar, 200 μm.
(B) Late tornaria (45 days post fertilization). Larvae 1–20 are displayed in ventral view focused on the surface ectoderm unless otherwise specified. The summary diagram to the left of the in situ panels reveals that an intermediate Hox-expressing trunk domain (yellow) is added to the larval anteroposterior axis at late larval stages. This domain becomes the juvenile trunk after metamorphosis. Anterior is shown in blue, and far posterior is shown in red. Black lines represent the anterior and posterior boundaries of gene expression. Scale bar, 1 mm.
a, anus; ao, apical organ; cb, circum-oral ciliary band; g, oral groove; m, mouth; pc, protocoel; pd, protocoel duct; pol, pre-oral lobe; pp, protocoel pore; pre, pre-oral loop; post, post-oral loop; t, telotroch. See also Figures S2 and S4 and Table S1.
Current Biology  , 87-95DOI: ( /j.cub )
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5. Figure 4
Activation of Trunk-Patterning Genes Is Delayed in S. californicum Relative to the Direct Developing S. kowalevskii
Models summarizing the development of the major domains of the developing AP axis in both S. californicum and S. kowalevskii. In S. californicum, most of the larval ectoderm has an anterior identity (blue), with an early initiation of the far posterior domain (A). The development of the anterior/mid-trunk (yellow) is delayed until the end of larval development. By contrast, the transcriptional domains that define the proboscis, collar, and trunk of S. kowalevskii are defined early in embryogenesis (B).
Current Biology  , 87-95DOI: ( /j.cub )
Copyright © 2017 Elsevier Ltd Terms and Conditions