title: Chromosomal mapping and molecular characterization of ribosomal RNA genes in Lebias fasciata (Teleostei, Cyprinodontidae).
abstract: Chromosome location of major (18S, 5.8S and 28S) and 5S ribosomal RNA genes (rDNAs) was examined in Lebias fasciata collected from different Italian blackish-waters, using silver (Ag)- and chromomycin A3 (CMA3)-staining and/or fluorescence in situ hybridization (FISH). Both 18S and 5S rDNA probes for FISH were obtained with polymerase chain reaction-directed cloning from genomic DNA of the examined species. Nucleolar organizer regions (NORs) containing the major rDNAs showed intraspecific polymorphism in number as detected by Ag-and CMA3-staining and FISH with the 18S rDNA probe. On the other hand, 5S rDNA loci constantly occurred on one chromosome pair and co-localized with a pair of the major rDNA loci as evidenced by two-color FISH using the 5S and 18S rDNA probes. Sequential CMA3- and Ag-NOR staining and FISH revealed apparent inactivation of some NORs. The cloned 5S rDNA was found to contain some TATA-like sequences that might play an important role in the regulation of gene expression.
authors.affiliation: Dipartimento di Biologia Animale, Università di Catania, Via Androne 81-95124 Catania, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Tigano
authors.forename: L
authors.initials: L
authors.lastname: Rocco
authors.forename: V
authors.initials: V
authors.lastname: Ferrito
authors.forename: D
authors.initials: D
authors.lastname: Costagliola
authors.forename: A M
authors.initials: AM
authors.lastname: Pappalardo
authors.forename: V
authors.initials: V
authors.lastname: Stingo
mesh_terms: D000818:Animals; D001483:Base Sequence; D014128:Chromomycin A3 / Q000032:analysis; D002871:Chromosome Banding; D002874:Chromosome Mapping; D020459:Genes, rRNA; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D007695:Killifishes / Q000235:genetics*; D008969:Molecular Sequence Data; D009697:Nucleolus Organizer Region; D016622:Silver Staining
chemical_list: D014128:Chromomycin A3