BMP signaling components in embryonic transcriptomes of the hover fly Episyrphus balteatus (Syrphidae)
1 University of Chicago, Dept. of Organismal Biology and Anatomy, CLSC 921B, 920 E. 58th Street, Chicago, IL 60637, USA
2 Current Address: University of Heidelberg, Centre for Organismal Studies, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
3 Argonne National Laboratory, Institute for Genomics & Systems Biology, 9700 S. Cass Avenue, Argonne, IL 60439, USA
BMC Genomics 2011, 12:278 doi:10.1186/1471-2164-12-278Published: 31 May 2011
In animals, signaling of Bone Morphogenetic Proteins (BMPs) is essential for dorsoventral (DV) patterning of the embryo, but how BMP signaling evolved with changes in embryonic DV differentiation is largely unclear. Based on the extensive knowledge of BMP signaling in Drosophila melanogaster, the morphological diversity of extraembryonic tissues in different fly species provides a comparative system to address this question. The closest relatives of D. melanogaster with clearly distinct DV differentiation are hover flies (Diptera: Syrphidae). The syrphid Episyrphus balteatus is a commercial bio-agent against aphids and has been established as a model organism for developmental studies and chemical ecology. The dorsal blastoderm of E. balteatus gives rise to two extraembryonic tissues (serosa and amnion), whereas in D. melanogaster, the dorsal blastoderm differentiates into a single extraembryonic epithelium (amnioserosa). Recent studies indicate that several BMP signaling components of D. melanogaster, including the BMP ligand Screw (Scw) and other extracellular regulators, evolved in the dipteran lineage through gene duplication and functional divergence. These findings raise the question of whether the complement of BMP signaling components changed with the origin of the amnioserosa.
To search for BMP signaling components in E. balteatus, we generated and analyzed transcriptomes of freshly laid eggs (0-30 minutes) and late blastoderm to early germband extension stages (3-6 hours) using Roche/454 sequencing. We identified putative E. balteatus orthologues of 43% of all annotated D. melanogaster genes, including the genes of all BMP ligands and other BMP signaling components.
The diversification of several BMP signaling components in the dipteran linage of D. melanogaster preceded the origin of the amnioserosa.