Schmidt-Ott Lab

Embryonic Axis Determinants in Flies, Midges, and Mosquitoes

We discovered that symmetry-breaking anterior axis determinants vary greatly between species of the insect order Diptera (true flies). These factors are expressed in long-range concentration gradients and serve as global pattern organizers with many direct target genes. In D. melanogaster, specification of the primary body axis relies in large part on the homeodomain transcription factor Bicoid, but other fly species use unrelated proteins for the same purpose and lack the bicoid gene altogether. Why anterior determinants differ between species is unknown. We use the evolution axis determinants in dipteran embryos as a model to address the general question of what holds developmental gene networks together over many million years and under which conditions they undergo radical change.

Figure: The phylogenetic tree indicates the occurrence of anterior axis determinants in dipteran families. The phylogeny is based on Wiegmann et. al., 2011, PNAS 108: 5690-5695.

Figure: First instar cuticles of Clogmia albipunctata in dorsal view with anterior to the left. Top: A double abdomen following knockdown of maternal odd-paired transcript. Bottom: a wild-type cuticle (Yoon et al. 2019).

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