title: Chromosomal evolution in Rattini (Muridae, Rodentia).
abstract: The Rattini (Muridae, Murinae) includes the biologically important model species Rattus norvegicus (RNO) and represents a group of rodents that are of clinical, agricultural and epidemiological importance. We present a comparative molecular cytogenetic investigation of ten Rattini species representative of the genera Maxomys, Leopoldamys, Niviventer, Berylmys, Bandicota and Rattus using chromosome banding, cross-species painting (Zoo-fluorescent in situ hybridization or FISH) and BAC-FISH mapping. Our results show that these taxa are characterised by slow to moderate rates of chromosome evolution that contrasts with the extensive chromosome restructuring identified in most other murid rodents, particularly the mouse lineage. This extends to genomic features such as NOR location (for example, NORs on RNO 3 are present on the corresponding chromosomes in all species except Bandicota savilei and Niviventer fulvescens, and the NORs on RNO 10 are conserved in all Rattini with the exception of Rattus). The satellite I DNA family detected and characterised herein appears to be taxon (Rattus) specific, and of recent origin (consistent with a feedback model of satellite evolution). BAC-mapping using clones that span regions responsible for the morphological variability exhibited by RNO 1, 12 and 13 (acrocentric/submetacentric) and their orthologues in Rattus species, demonstrated that the differences are most likely due to pericentric inversions as exemplified by data on Rattus tanezumi. Chromosomal characters detected using R. norvegicus and Maxomys surifer whole chromosome painting probes were mapped to a consensus sequence-based phylogenetic tree thus allowing an objective assessment of ancestral states for the reconstruction of the putative Rattini ancestral karyotype. This is thought to have comprised 46 chromosomes that, with the exception of a single pair of metacentric autosomes, were acrocentric in morphology.
authors.affiliation: Evolutionary Genomics Group, Botany and Zoology Department, University of Stellenbosch, Private Bag X1, 7604 Matieland, South Africa.
authors.forename: Daleen
authors.initials: D
authors.lastname: Badenhorst
authors.forename: Gauthier
authors.initials: G
authors.lastname: Dobigny
authors.forename: Filomena
authors.initials: F
authors.lastname: Adega
authors.forename: Raquel
authors.initials: R
authors.lastname: Chaves
authors.forename: Patricia C M
authors.initials: PC
authors.lastname: O'Brien
authors.forename: Malcolm A
authors.initials: MA
authors.lastname: Ferguson-Smith
authors.forename: Paul D
authors.initials: PD
authors.lastname: Waters
authors.forename: Terence J
authors.initials: TJ
authors.lastname: Robinson
mesh_terms: D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002871:Chromosome Banding; D020223:Chromosome Painting / Q000379:methods; D022202:Chromosomes, Artificial, Bacterial; D033481:Chromosomes, Mammalian / Q000235:genetics*; D004276:DNA, Satellite / Q000235:genetics; D005260:Female; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D007621:Karyotyping; D008297:Male; D008969:Molecular Sequence Data; D051189:Murinae / Q000235:genetics*; D009697:Nucleolus Organizer Region / Q000235:genetics; D051381:Rats; D016415:Sequence Alignment
chemical_list: D004276:DNA, Satellite