TABLE 1.

Classification and characteristics of sdt alleles analyzed

Class	Allele	Origina	Morphogenetic phenotypec	Light-induced degeneration	Molecular defect
I	sdtEH681	EH	No	No	Stop codon in exon 3g
	sdtXH21	HK	No	No	No mutation found
	sdtM120	HK	No	Nof	Stop codon in exon 3
	sdt7D22	W	Yes	Nof	ND
II	sdtXP96	W	Yesd	Weak	Stop codon at the end of exon 6g
III	sdtN5	Wb	Noe	Yes	Stop codon in L27Ng
IV	sdtK70	HK	Yes	Yes	No mutation found
	sdtK85	HK	Yes	Yes	Stop codon in L27N
	sdtE195	HK	Yes	Yes	Stop codon in L27C

^aEH, Eberl and Hilliker (1988); W, Wieschaus et al. (1984); HK, T. Hummel and C. Klämbt (unpublished data).

^bThis allele is also named sdt^NO5 (Eberl and Hilliker 1988) or sdt^XNO5 (Hong et al. 2001). The identity of these alleles was verified by sequence analysis.

^cRevealed in the light microscope as defects in the shape of the rhabdomeres.

^dStalk membranes of mutant PRCs are reduced by 40% (Hong et al. 2003).

^eStalk membranes of mutant PRCs are reduced by 50% (see Figure 2).

^fOccasionally, one PRC per ommatidium was absent.

^gHong et al. (2003).