Fig. 1. Cell specificity of expression and overexpression of the Sgs3 promoter in the salivary gland cells. Staining in the distal (D) parts and absence of staining in the proximal (P) parts of the salivary gland in Sgs3-Gal4 UAS-lacZ larvae (A-C). No expression was seen in young (about 100 hours) larvae (A). The beginning of expression was seen in the salivary glands of older (B) and late (C) larvae. Binding of antibodies against SuUR protein in polytene chromosomes of distal part of salivary gland of young SuUR/SuUR Sgs3-Gal4 UAS-SuUR⁺ larvae: immunofluorescence (D) and phase contrast (E). Arrows point to a smaller polytene chromosome in the proximal part of the salivary gland that does not bind the antibodies. Binding of antibodies against SuUR protein in polytene chromosomes of the distal part of salivary gland of wildtype (F,G) shown by immunofluorescence (F) and phase contrast (G). Recognition of an additional band in the SuUR/SuUR Sgs3-Gal4 UAS-SuUR⁺ larvae by the SuUR antibodies on western blots (H)