Figures

- Duplicated Hox genes in the spider Cupiennius salei

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Figure 1   Alignment of chelicerate Proboscipedia, Deformed, Sex comb reduced, Ultrabithorax sequences. Aligned is a fragment covering the hexapeptide (core in red) and homeodomain (blue) plus some flanking sequences. The deduced proteins sequences are from the chelicerates Cupiennius salei (Cs; American wandering spider), Achaearanea tepidariorum (At; common house spider), Archegozetes longisetosus (Al; mite), Endeis spinosa (Es; seaspider) the fruit fly Drosophila melanogaster (Dm; insect), the centipedes Pachymerium ferrugineum (Pf; myriapod), Strigamia maritima (Sm; myriapod), and the isopod Porcellio scaber (Ps; crustacean). Amino acids identical to the upper sequence are indicated as dashed "-"; dots "." are used to indicate gaps that have been introduced for alignment purposes. The linker between hexapeptide and homeodomain in the Es-pb sequence is rather long, therefore 19aa are not shown (marked as //19aa// in the alignment). Please note, some of the At, Al and Pf sequences from the GenBank still contain ambiguous sites that result in an unknown amino acid in the deduced protein sequence; these are indicated as "X" in the alignment. Accession numbers of the sequences used: Cs: AM419029, CAA07498, AM419032, AM419030, AM419031, CAA07500, CAA07501; At: AF151997, AF151995, AF151996, AF151998; Al: AF071406, AF071403, AF071407; Es: ABD46724. ABD46727, ABD46728; Dm: CAA45272, NP_477201, NP_524248, NP_536752; Pf: CAB75743, CAB75746; Sm: ABD16212, Ps: BAE97002.

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Figure 2   Expression pattern of the Cs-pb gene. (A) Limb bud stage, proboscipedia (pb) is expressed in the pedipalpal segment (Pp) and walking leg segments (L1-L4). The expression is most prominent in the appendages itself, but there is also some weaker expression in the ventral ectoderm (arrows). There is no expression in the cheliceral segment (Ch) or in the opisthosomal segments. (B) Inversion stage, pb is expressed in the appendages of the Pp and L1-L4 segments and in spots (arrowheads) in the ectoderm ventral to the appendages. Also at these older stages the cheliceral and opisthosomal segments are free of expression. Both embryos: ventral view.

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Figure 3   Expression pattern of the Cs-Dfd-1 and Cs-Dfd-2 genes. The Cs-Dfd-1 gene (A-C) and the Cs-Dfd-2 gene (D-F) are expressed in the four segments that bear the walking legs (L1-L4). Expression is seen in the appendages as well as in the ventral ectoderm. The ventral ectoderm expression of Cs-Dfd-1 is stronger than the one of Cs-Dfd-2, especially at the older stages (B and C compared with E and F). The expression patterns in the legs are different for the two genes (most obvious in C an F), while in addition, Cs-Dfd-2 expression in L3 and L4 is weaker compared to the expression in L1 and L2. The level of Cs-Dfd-1 expression is similar for all four legs. A and D: ventral view of limb bud stage, B and E: ventral view of limb stage before inversion, C and F: lateral view of inversion stage. There is never ever expression of any of the two spider Dfd genes in the cheliceral (Ch), pedipalpal (Pp), or opisthosomal segments.

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Figure 4   Expression pattern of the Cs-Scr-1 and Cs-Scr-2 genes. Expression of the Cs-Scr-1 gene (A-C) and the Cs-Scr-2 gene (D-F). At the limb bud stage Scr-1 is more or less homogenously expressed in L2, L3 and L4 (arrow in A). At later stages there is expression in rings in the legs of L3 and L4 (B) and later also weak expression in the legs of L2 (C). Scr-2 expression starts as small spots in the ventral ectoderm of L2, L3 and L4 (arrowheads in D) that persist during further development (E,F). Later there is also Scr-2 expression in the legs of L3 and L4, but in contrast to Scr1 we never observed expression in the legs of L2 (F). Ch: cheliceres, Pp: pedipalps, L1-L4: walking leg 1-4.

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Figure 5   Expression pattern of the Cs-Ubx-1 and Cs-Ubx-2 genes. The anterior expression border of both Ubx genes is in the second opisthosomal segment (O2). The one of Cs-Ubx-1 (A) is at the anterior edge of O2, while the one of Cs-Ubx-2 is at posterior portion of O2 and corresponds to the parasegment boundary [15]. The opisthosomal limb primordia that will form the respiratory organs and spinnerets are visible on O2-O5. Abbreviations: L4: walking leg 4, O1-O6: opisthosomal segment 1-6.

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Figure 6  Schematic representation of the segmental expression patterns of the Hox genes in the spider Cupiennius salei. The segmental organization of the spider and the expression domains of engrailed (en; dark blue) and wingless (wg; bright blue) are shown at the top [see Ref. 31], below are the expression domains of the various Hox genes. Data from: this paper, Refs. [15, 17-19]. Note that the posterior expression domain of the anterior Hox genes (lab, pb, Hox3, Dfd, Scr, ftz) is in the segment of the fourth walking leg and corresponds to the tagma boundary between prosoma and opisthosoma. The expression of the posterior Hox genes (Antp, Ubx, abdA, AbdB) expands to the very posterior end of the embryo. Abbreviations: Oc: ocular; Ch: cheliceral segment; Pp: pedipalpal segment; L1-L4: walking leg segment 1-4; O1-O12: opisthosomal segment 1-12.