Karyotypic differentiation through chromosome fusion and number reduction in Imparfinis hollandi (Ostariophysi, Heptapteridae)

Vladimir Pavan Margarido, Orlando Moreira-Filho
2008 Genetics and Molecular Biology  
The Neotropical Heptapteridae fish Imparfinis hollandi, endemic to the Iguaçu River Basin (Brazil), was cytogenetically analyzed and the diploid chromosome number of 2n = 42 chromosomes was determined (22m + 10sm + 10st), the lowest diploid number in this genus and family. Like other Heptapteridae species, only one NOR-bearing chromosome pair was detected by silver nitrate staining. Dark heterochromatic blocks were visualized in only three chromosome pairs, and chromomycin A 3 + bands were
more » ... 3 + bands were coincident with Ag-NORs. Although no intercalary (TTAGGG) n sequence was observed through FISH with a telomere probe, an asymmetric karyotype showing four large chromosome pairs with diploid chromosome number reduction suggests that tandem chromosome fusions probably occurred during the karyotypic differentiation of Imparfinis hollandi.
doi:10.1590/s1415-47572008000200012 fatcat:irghuaiodngf3o5nzehdbazjtm