Molecular conservation of metazoan gut formation: evidence from expression of endomesoderm genes in Capitella teleta (Annelida)

EvoDevo

Elaine C Seaver³  Emi Yamaguchi¹  Michael J Boyle² 

[1] Kewalo Marine Laboratory, PBRC/University of Hawaii, 41 Ahui Street, Honolulu, HI 96813, USA;Naos Island Laboratory, Smithsonian Tropical Research Institute, Apartado 0843-03089, Panamá, República de Panamá;Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd. St., Augustine, FL 32080, USA

关键词: spiralian;    hybridization;    kernel;    gut development;    digestive system;    endoderm;   

Others  :  1093230
DOI  :  10.1186/2041-9139-5-39

 received in 2014-06-22, accepted in 2014-09-17,  发布年份 2014

【 摘 要 】

Background

Metazoan digestive systems develop from derivatives of ectoderm, endoderm and mesoderm, and vary in the relative contribution of each germ layer across taxa and between gut regions. In a small number of well-studied model systems, gene regulatory networks specify endoderm and mesoderm of the gut within a bipotential germ layer precursor, the endomesoderm. Few studies have examined expression of endomesoderm genes outside of those models, and thus, it is unknown whether molecular specification of gut formation is broadly conserved. In this study, we utilize a sequenced genome and comprehensive fate map to correlate the expression patterns of six transcription factors with embryonic germ layers and gut subregions during early development in Capitella teleta.

Results

The genome of C. teleta contains the five core genes of the sea urchin endomesoderm specification network. Here, we extend a previous study and characterize expression patterns of three network orthologs and three additional genes by in situ hybridization during cleavage and gastrulation stages and during formation of distinct gut subregions. In cleavage stage embryos, Ct-otx, Ct-blimp1, Ct-bra and Ct-nkx2.1a are expressed in all four macromeres, the endoderm precursors. Ct-otx, Ct-blimp1, and Ct-nkx2.1a are also expressed in presumptive endoderm of gastrulae and later during midgut development. Additional gut-specific expression patterns include Ct-otx, Ct-bra, Ct-foxAB and Ct-gsc in oral ectoderm; Ct-otx, Ct-blimp1, Ct-bra and Ct-nkx2.1a in the foregut; and both Ct-bra and Ct-nkx2.1a in the hindgut.

Conclusions

Identification of core sea urchin endomesoderm genes in C. teleta indicates they are present in all three bilaterian superclades. Expression of Ct-otx, Ct-blimp1 and Ct-bra, combined with previously published Ct-foxA and Ct-gataB1 patterns, provide the most comprehensive comparison of these five orthologs from a single species within Spiralia. Each ortholog is likely involved in endoderm specification and midgut development, and several may be essential for establishment of the oral ectoderm, foregut and hindgut, including specification of ectodermal and mesodermal contributions. When the five core genes are compared across the Metazoa, their conserved expression patterns suggest that ‘gut gene’ networks evolved to specify distinct digestive system subregions, regardless of species-specific differences in gut architecture or germ layer contributions within each subregion.

【 授权许可】

   
2014 Boyle et al.; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

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Figure 4.

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