ceh-32 is a C.elegans homeobox gene of the six/sine oculis (so) gene family. It belongs to the
six3 subclass of genes which include mouse
six3, chicken, mouse and Drosophila optix. From an embryonic cDNA library (kindly provided by P. Okkema) we cloned a
ceh32 cDNA. The sequence of this 1860 bp cDNA clone revealed an open reading frame of 439 amino acids. The locus is present on the cosmid W05E10. RNAi of
ceh-32 caused a Vab phenotype with the typical "notched head" aspect, reminiscent of the Vab-3 (Pax-6) phenotype. The alae reach the anterior part of the head, whereas in normal animals they do not. This is also similar to the Vab-3 phenotype, where some of posterior structures reach more anterior locations. We also observed gonadal defects: the gonads are smaller and/or misplaced. To examine the expression pattern of
ceh-32, promotor gfp fusion constructs were generated. Analysis of the gfp transgenic lines showed a dynamic embryonic and post-embryonic expression. In embryonic stages, the expression in the anterior H0, H1 lineage overlaps with
vab-3. In post-embryonic stages
ceh-32 is expressed in
e1,
e2 and
e3 epithelial cells of the pharynx, in M3 myoblast of the pharynx, in
g1 and
g2 gland cells of the pharynx, as well as in Z1 and Z2 somatic gonad precursor cells and later in the gonadal sheath cells. By Northern blot analysis of mixed worm stages a decreased
ceh-32 expression was observed in a
vab-3 genetic background. We do not know whether this is due to the lack of transcriptional control via
vab-3, or to the lack of
ceh-32 expressing cells. This is under investigation. We also investigated the role and expression of
ceh-33, 34 and 35, three other six/so homeobox genes. gfp reporters for
ceh-33 and 34 showed very weak expression in the pharynx of late embryos and early larvae. For
ceh-35::gfp we saw no expression. For
ceh-33 and 35 we were able to amplify gene specific cDNA fragments from the 3' and 5' end, respectively, while we were not able to amplify
ceh-34. RNAi of
ceh-33 and
ceh-35 caused gonadal defects in the injected worms with a small amount of normal oocytes produced.