Expression of Glomeris marginata collier. Expression of collier (col) (A-E) and combined expression of col and engrailed (en) (F-H). All embryos except the embryo shown in (a) are in ventral view. (A) Stage 0.2 embryo. col is expressed in a broad stripe in the anterior of the developing embryo posterior to the ocular field (cf. A' which shows a DAPI staining of the same embryo). (a) Same embryo as in A; lateral view. (B) Stage 1 embryo. Expression of col fades from the ventral-most tissue (asterisk) (cf. B', DAPI counterstaining). (C) Stage 2 embryo. Last remnants of col-expression at the junction between mandibular and premandibular/intercalary segment. (D) Stage 5 embryo. Expression appears in the trunk segments in dorso-lateral patches (asterisks) and thin stripes in the anterior of the segments (double-arrowhead). Weak expression appears in the ventral nervous system (arrow) (cf. D', DAPI counterstaining). (E) Stage 6 embryo. Expression in dorso-lateral patches and segmental stripes in the trunk remains (asterisks and double-arrowhead). Expression in the ventral nervous systems enhances (filled circle). Expression appears at the anterior rim of the head (arrowheads). (F) Stage 0.2 embryo. Expression of col virtually abuts expression of en in mandibular segment. The distance to the en-stripe in the antennal segment is small (arrow). Arrowheads point to en expression in anntennal and mandibular segments. (G) Stage 0.4 embryo. Expression of col does not abut the mandibular en stripe any longer; the distance to the antennal en-stripe is increased (arrow). Arrowheads as in F. (H) Stage 0.4 embryo. col-stripe is further narrowing; distance to mandibular en-stripe is increased. Arrow and arrowheads as in F. Note that at these early developmental stages en is not yet expressed in the premandibular/intercalary segment. For details on en expression in young stages see . Abbreviations: an, antennal segment; cu, cumulus; md, mandibular segment; oc, ocular field; PS0, parasegment 0; saz, segment addition zone; T1, first trunk segment.
Janssen et al. BMC Evolutionary Biology 2011 11:50 doi:10.1186/1471-2148-11-50