Quantitative assessment of Hox complex expression in the indirect development of the polychaete annelid Chaetopterus sp
Abstract
A prediction from the set-aside theory of bilaterian origins is that pattern formation processes such as those controlled by the Hox cluster genes are required specifically for adult body plan formation. This prediction can be tested in animals that use maximal indirect development, in which the embryonic formation of the larva and the postembryonic formation of the adult body plan are temporally and spatially distinct. To this end, we quantitatively measured the amount of transcripts for five Hox genes in embryos of a lophotrochozoan, the polychaete annelid Chaetopterus sp. The polychaete Hox complex is shown not to be expressed during embryogenesis, but transcripts of all measured Hox complex genes are detected at significant levels during the initial stages of adult body plan formation. Temporal colinearity in the sequence of their activation is observed, so that activation follows the 3′–5′ arrangement of the genes. Moreover, Hox gene expression is spatially localized to the region of teloblastic set-aside cells of the later-stage embryos. This study shows that an indirectly developing lophotrochozoan shares with an indirectly developing deuterostome, the sea urchin, a common mode of Hox complex utilization: construction of the larva, whether a trochophore or dipleurula, does not involve Hox cluster expression, but in both forms the complex is expressed in the set-aside cells from which the adult body plan derives.
Additional Information
© 2000 National Academy of Sciences. Contributed by Eric H. Davidson, January 21, 2000. We thank Profs. Ellen Rothenberg (California Institute of Technology), André Adoutte (Centre National de la Recherche Scientifique), and William McGinnis (University of California at San Diego) for their helpful reviews. This work was supported by the Fundamental Biology Research Program of the Life Sciences Division of the National Aeronautics and Space Administration/Ames Grant NAG2-1368.Attached Files
Published - PNAS-2000-Peterson-4487-92.pdf
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Additional details
- PMCID
- PMC18261
- Eprint ID
- 35054
- Resolver ID
- CaltechAUTHORS:20121023-154045360
- NASA
- NAG2-1368
- Created
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2012-10-24Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field