title: Classical and molecular cytogenetic characterization of allochthonous European bitterling Rhodeus amarus (Cyprinidae, Acheilognathinae) from Northern Italy.
abstract: A cytogenetical study was carried out on 34 specimens of the European bitterling Rhodeus amarus (Teleostei: Cyprinidae, Acheilognathinae) from four rivers of the Venice district (NE Italy). This allochthonous fish species was accidentally introduced in the North-East of Italy about 20 years ago and is now rapidly spreading all over the rivers of the Northern part of the country. All the studied specimens are characterised by the same karyotype (2n = 48: 8M + 20SM + 20ST), i.e., the typical one of the native populations of the species. However, a polymorphism in the number of NOR bearing chromosomes has been found. In fact, in addition to the main species-specific NORs, on the short arms of chromosome pair 7, two to five additional 18S rDNA sites have been revealed by FISH in different specimens. Sequential staining with silver nitrate, chromomycin A(3) and DAPI revealed that most of the additional sites are inactive and CMA(3)-positive. Data herein reported confirm that in spite of an overall morphological karyological conservativeness, significant differences for the finer cytogenetic features can be found within the Acheilognathinae with the 2n = 48 and NF = 76 karyotype.
authors.affiliation: Institute of Marine Sciences, National Council for Research, Venice, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Libertini
authors.forename: Luciana
authors.initials: L
authors.lastname: Sola
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Rampin
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Rossi
authors.forename: Koji
authors.initials: K
authors.lastname: Iijima
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ueda
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000235:genetics; D003530:Cyprinidae / Q000235:genetics*; D003582:Cytogenetics; D017404:In Situ Hybridization, Fluorescence; D007558:Italy; D007621:Karyotyping