Figure 2. (A–D) Ventral accumulation of GD does not require the activities of Snk, Ea or Spz. PVF was obtained from donor embryos produced by GD-GFP expressing females that were mutant for either snk (snk¹/snk²), ea (ea⁴/Df(3R)ea^5022rx1) or spz (spz²/spz⁴), then transplanted to embryos from females of the same dorsal group genotype lacking GD-GFP expression, as described in Cho et al.²⁴ The two snk mutations have been reported to carry stop codons near the N-terminus of the open reading frame.³⁴ No ea mRNA can be detected in the ea⁴/Df(3R)ea^5022rx1 mutant background.³⁵ Thus the snk and ea mutant backgrounds can be considered null for the respective proteins. While the spz² and spz⁴ alleles behave genetically as amorphic alleles, their associated mutant lesions have not been characterized and it is unclear whether they represent protein nulls. Description of the dorsal group mutant alleles used in these studies can be found on Flybase. (E and F) Neither Ea-GFP nor Spz-GFP exhibit ventral accumulation in the egg PVS. PVF from embryos produced by females expressing Ea-GFP or Spz-GFP under the control of the nos-Gal4:VP16³⁶ driver was transplanted into the PVS of wild-type embryos. Details of the generation of the Ea-GFP and Spz-GFP transgenic lines can be found in Cho et al.²⁴ GFP appears blue in all panels.