Fig. 2. Mapping and molecular analysis of Df^st7, Df^st8 and vox^st9. (A) Genomic DNA from pools of wild type, Df^st7, Df^st8 and Df^st4 embryos were tested with LG13 SSLP markers and primers for vox and vent. These mutations remove distinct but overlapping sets of markers on LG13. All markers were also tested in individual embryos to confirm the presence or absence of the PCR products (data not shown). (B) Linkage map of LG13 showing the positions of vox and vent and the regions deleted in Df^st7, Df^st8 and Df^st4 (vertical lines indicate deleted regions, broken vertical lines denote uncertainty in the locations of the breakpoints). Marker distances are based on Shimoda et al. (Shimoda et al., 1999). We localized vox and vent by scoring polymorphisms in both genes in the HS meiotic mapping panel (Kelly et al., 2000). (C) The vox^st9 mutation is tightly linked to vox. All dorsalized embryos (n=291) had only the mutant vox allele, indicating that their genotype was Df^st7/vox^st9. Three different genotypes were observed in embryos with a wild-type phenotype: only the wild-type allele (+/+ or Df^st7/+), both wild-type and mutant alleles (vox^st9/+; arrowhead), and only the mutant allele (Df^st7/vox^st9; asterisk). The Df^st7/vox^st9 genotype is only partially penetrant, because some of these embryos have a wild-type phenotype. Analysis of SSLP markers confirmed that the vox^st9 mutation resides in the distal region of LG13 (data not shown). (D) Schematic representation of Vox protein and the lesion in the vox^st9 mutation. The vox^st9 mutation changes the initiation codon (ATG) of the vox open reading frame to GTG. The second in-frame ATG occurs at codon 170, near the end of the homeodomain.

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