A comparative molecular approach to mesodermal patterning in basal deuterostomes: the expression pattern of Brachyury in the enteropneust hemichordate Ptychodera flava
Abstract
This work concerns the formation of mesoderm in the development of an enteropneust hemichordate, Ptychodera flava, and the expression of the Brachyury gene during this process. Brachyury expression occurs in two distinct phases. In the embryo, Brachyury is transcribed during gastrulation in the future oral and anal regions of the gut, but transcripts are no longer detected by 2 weeks of development. Brachyury expression is not detected during the 5 months of larval planktonic existence. During this time, the adult coeloms begin to develop, originating as coalescences of cells that appear to delaminate from the wall of the gut. Brachyury expression cannot be detected again until metamorphosis, when transcripts appear in the mesoderm of the adult proboscis, collar and the very posterior region of the trunk. It is also expressed in the posterior end of the gut. At no time is Brachyury expressed in the stomochord, the putative homologue of the chordate notochord. These observations illuminate the process of maximal indirect development in Ptychodera and, by comparison with patterns of Brachyury expression in the indirect development of echinoderms, their sister group, they reveal the evolutionary history of Brachyury utilization in deuterostomes.
Additional Information
Copyright © 1999 by Company of Biologists. Accepted 16 October; published on WWW 3 December 1998. We would like to thank Mike Hadfield and the members of his laboratory (Catherine Unabia, Scott Schellhammer and Brian Nedved) for their tireless efforts to make K.J.P.'s trips to the Kewalo Marine Laboratory enjoyable and successful. We would also like to thank Richard Chock for going above and beyond the call of duty to tow for Ptychodera larvae. We also want to thank Bob Turring of the Graphic Arts Facility (Caltech) for drawing Fig. 1 and Vanessa Moy for drawing Fig. 4E. K.J.P. would also like to thank members of the Davidson laboratory, especially Andrew Ransick, for their advice with in situ hybridization. We are grateful to Dr James Coffman of Caltech for review and advice on a draft of this manuscript. This work was supported by grants from the NIH (HD-05753) to E.H.D., and HFSP (RG212/1997) to N.S. and R.A.C.; K.J.P. was supported by a Caltech Molecular Geobiology Fellowship.Attached Files
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Additional details
- Eprint ID
- 12988
- Resolver ID
- CaltechAUTHORS:PETdev99
- NIH
- HD-05753
- Human Frontier Science Program
- RG212/1997
- Caltech Molecular Geobiology Fellowship
- Created
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2009-01-14Created from EPrint's datestamp field
- Updated
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2019-10-03Created from EPrint's last_modified field