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caudal and even‐skipped in the annelid Platynereis dumerilii and the ancestry of posterior growth
Author(s) -
Rosa Renaud,
Prud'homme Benjamin,
Balavoine Guillaume
Publication year - 2005
Publication title -
evolution and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 78
eISSN - 1525-142X
pISSN - 1520-541X
DOI - 10.1111/j.1525-142x.2005.05061.x
Subject(s) - annelid , biology , body plan , brachyury , anatomy , evolutionary biology , trunk , mesoderm , embryo , gene , genetics , ecology , embryonic stem cell
Summary In order to address the question of the conservation of posterior growth mechanisms in bilaterians, we have studied the expression patterns of the orthologues of the genes caudal , even‐skipped , and brachyury in the annelid Platynereis dumerilii . Annelids belong to the still poorly studied third large branch of the bilaterians, the lophotrochozoans, and have anatomic and developmental characteristics, such as a segmented body plan, indirect development through a microscopic ciliated larva, and building of the trunk through posterior addition, which are all hypothesized by some authors (including us) to be present already in Urbilateria , the last common ancestor of bilaterians. All three genes are shown to be likely involved in the building of the anteroposterior axis around the slit‐like amphistomous blastopore as well as in the patterning of the terminal anus‐bearing piece of the body (the pygidium). In addition, caudal and even‐skipped are likely involved in the posterior addition of segments. Together with the emerging results on the conservation of segmentation genes, these results reinforce the hypothesis that Urbilateria had a segmented trunk developing through posterior addition.