Question

To investigate transformer (tra) gene expression during sex determination in Drosophila, you perform in situ hybridization (FISH) and immunostaining. Fill in the table with the results you expect to observe following the example given in the first row.

Experiment	Female embryos	Male embryos
Immunostaining with an antibody to Sxl protein	stain positively	no staining
FISH with a probe to exon 2 of tra
FISH with a probe to exon 3 of tra
Immunostaining with an antibody to Tra protein

Match sex phenotype to each genotype of a transformer mutant fly:

XX: ____________;     XY: ___________

Answer 1

Experiment	Female embryos	Male embryos
Immunostaining with an antibody to Sxl protein	stain positively	no staining
FISH with a probe to exon 2 of tra	stain positively	stain positively
FISH with a probe to exon 3 of tra	stain positively	no staining
Immunostaining with an antibody to Tra protein	stain positively	no staining

Gene tra at exon 3 has no significance in drosophila male. So we do not get any fluoresecne if FISH hybridized in male but we get the flurosence in female. The other gene Sex-lethal (Sxl) disables in male drosophila. Sxl gene is depend upon X:A [X-sex chromosome and A- autosome] signal, male has X;2A so the Sxl gene does not expressed. Gene tra express when Sxl express. Gene tra exon 2 will show results in male. The probe will attach here but expression will not occur because tra at exon2 is stopped.