Figure 7. Anterior axis determinants in Diptera.

The phylogenetic tree of dipteran families is based on published data and shows Cylorrhapha in green (Wiegmann et al., 2011). Mya, million years ago.

Figure 7—figure supplement 1. Occurrence of panish in Chironomidae genomes.

Orthologs of panish in Chironomus piger and C. tentans have been reported previously (Klomp et al., 2015). We examined panish in recently published genome sequences of Polypedilum vanderplanki (Gusev et al., 2014), P. nubifer (Gusev et al., 2014), Clunio marinus (Kaiser et al., 2016), Belgica antarctica (Kelley et al., 2014), and Parochuls steinenii (Kim et al., 2017). The phylogeny is based on Cranston et al. (2012).

Figure 7—figure supplement 2. Maternal and zygotic transcript variant of Clogmia zerknüllt (Cal-zen).

Stage-specific RNA-seq read coverage of Cal-zen genomic locus above schematic sketches of Cal-zen^Mat and Cal-zen^Zyg transcript variants with open reading frame (black) and recovered UTR sequences. The RNA-seq reads were obtained from preblastoderm (0.5 hr-old), syncytial blastoderm (4 hr-old), cellular blastoderm (7 hr-old), and gastrulation stages (9 hr-old). Maternal zerknüllt expression is common in lower Diptera but was probably lost in the stem lineage of Cyclorrhapha (Stauber et al., 2002). It is possible that zerknüllt evolved a localization signal in this stem lineage, because in Megaselia abdita (Phoridae), a cyclorrhaphan fly with maternal bicoid expression and zygotic zerknüllt expression, the maternal bicoid transcript is localized at the anterior pole of the embryo while the zygotic zerknüllt transcript is localized on the apical side of blastoderm cells (Stauber et al., 1999), presumably through the same microtubule-dependent machinery (Bullock and Ish-Horowicz, 2001).