A Drosophila melanogaster cell line tested for the presence of active NORs by silver staining

Abstract

Silver staining was used to detect active NORs in a Drosophila melanogaster cell line (C1 82) characterized by dimorphic X chromosomes (XXL), one of the two Xs showing a marked increase in heterochromatin where the nucleolar organizer (NO) is located. The Q-banding technique was used to determine the karyotype characteristics of the line. Ag-positive NORs appeared only on structurally changed X chromosomes (XL), both in diploid and tetraploid cells, indicating that rRNA genes of XL are more active or numerous than those on normal homologues. A possible relationship between NOR stainability, the presence of an increased heterochromatic portion and the selective advantage of XXL cells, recurrent in numerous Drosophila female lines, is discussed.

The chromosomes of two Drosophila races: D. nasuta nasuta and D. nasuta albomicans III. Localization of nucleolar organizer regions

“…However, in Drosophila nasuta nasuta and D. n. albomicans as well as in D. hydei (Beck & Srdi~, 1979) this Ag-AS method fails to label the NORs specifically. So far in Drosophila only from a D. melanogaster cell line has a positive result of Ag-AS staining of NORs been reported (Privitera, 1980). In the two D. nasuta races studied the Ag-AS method stains the centric and pericentric heterochromatin regions of all chromosomes.…”