Salivary Gland Chromosomes

These are polytenic and because of their large size and clear landmarks, have been used extensively for cytogenetic analyses of Drosophila and other flies. The cultures to be used for this type of studies should be less crowded and moist. Third instar larvae can be used as they crawl out of the medium before the cuticle hardens. The larvae are placed in aceto-orcein or into 7% aqueous NaCl on microscope slides. A needle is used to hold the larva in place, and with a second needle placed behind the mouth parts the larva is decapitated and the salivary gland is pulled out. In aceto-orcein on a clean slide, the nuclei are stained in 5 to 10 min. The chromosomes may be spread by gentle pressure on the cover slide and after sealing the edge with wax, they can be examined under a light microscope. polytenic chromosomes, Drosophila , see Fig. S7; Lifschytz E 1983 J Mol Biol 164:17; Cold Spring Harb Symp Quant Biol 38 1974.

Figure S7.

Salivary gland chromosomes of Drosophila(Courtesy of Dr....