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Figure 1 | BMC Evolutionary Biology

Figure 1

From: atonal- and achaete-scute-related genes in the annelid Platynereis dumerilii: insights into the evolution of neural basic-Helix-Loop-Helix genes

Figure 1

Overview of formation the trunk nervous system in Platynereis. Expression of Pdu-elav, Pdu-syt, Pdu-TrpH, and Pdu-VAchT, as determined by WMISH, on a selection of larval stages is shown. All pictures are ImageJ projections and are ventral views (anterior up). The blue dotted lines indicate the position of the prototroch (a ring of ciliated cells involved in the locomotion of the larva) and therefore the separation between the prospective head (up) and trunk (down) regions. The position of the mouth region is indicated either by dotted red lines or a red asterisk, depending on the stage. The formation of the larval neurons is shown in A to E. A few neurons with stereotyped positions differentiate between 24 h to 48 h as seen by the expression of Pdu-elav and Pdu-syt (A-C). A single pair of neurons, located close to the mouth region, is serotonergic as seen by the expression of Pdu-TrpH (D), a few other neurons are cholinergic (as seen by the expression of Pdu-VAchT; E), and the other ones are of unknown identity. F to L depict the formation of the juvenile worm nervous system. See the main text for details. Arrows in J point to peripheral neurons associated with the parapodes. M to O are schematic drawings of the organization of the nervous system of 24 hpf, 48 hpf, and 72 hpf larvae. The neuroectodermal cells are indicated in yellow, the cells expressing Pdu-elav in red, and the Pdu-syt-expressing neurons in blue.

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