title: 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.
mesh_terms: D000818:Animals; D002460:Cell Line; D002871:Chromosome Banding; D002875:Chromosomes / Q000648:ultrastructure*; D004331:Drosophila melanogaster; D005260:Female; D007621:Karyotyping; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*; D010641:Phenotype; D012834:Silver; D013194:Staining and Labeling; D014960:X Chromosome / Q000648:ultrastructure
chemical_list: D012834:Silver