Nuclear DNA content determination in Characiformes fish (Teleostei, Ostariophysi) from the Neotropical region

Abstract

In the present study, nuclear DNA content was analyzed in 53 species of Characiformes fish from the Neotropical region. Diploid number ranged from 2n = 48 in Astyanax fasciatus, Gymnocorymbus ternetzi and Hyphessobrycon griemi to 2n = 102 in Potamorhina squamoralevis, with a modal number of 54 chromosomes. Nuclear DNA content ranged from 1.70 ± 0.04 pg of DNA per diploid nucleus in Acestrorhynchus pantaneiro to 3.94 ± 0.09 pg in Tetragonopterus chalceus. A general analysis showed a mean value of 2.9 pg of DNA per diploid nucleus. Very similar DNA content values were observed in the species of the family Cynodontidae which showed a variation of 3% between the two genera studied. Small variations were observed between populations of Gymnocorymbus ternetzi, Astyanax fasciatus and Moenkhausia sanctaefilomenae (Characidae, Tetragonopterinae). The subfamilies Tetragonopterinae and Acestrorhynchinae (Characidae) presented the widest range, about 96%. Even in those families in which diploid number and karyotypic formulae were conserved such as the families Anostomidae, Curimatidae, and Prochilodontidae, episodes leading to losses or gains of genetic material became fixed in their evolutionary history.

Nuclear DNA content in 20 species of Siluriformes (Teleostei: Ostariophysi) from the Neotropical region

“…The differences in nuclear DNA content found in the genus Rhamdia may be due to the presence of one to three supernumerary chromosomes in the population of the Jacutinga stream. A variation in DNA content among individuals, due to the presence of different numbers of supernumerary chromosomes, was also observed by Carvalho et al (2002) in their study of two populations of Moenkhausia sanctaefilomenae.…”

“…More recently, other studies on nuclear DNA content in Neotropical species were conducted by Oliveira et al (1992Oliveira et al ( , 1993aOliveira et al ( , 1993b in different species of Callichthyidae and by Carvalho et al (1998Carvalho et al ( , 2002 in fish species of the order Characiformes. Among the Siluriformes, a considerable diversity of karyotypes, determined by differences in diploid numbers and chromosome formulae, has been found (Oliveira and Gosztonyi, 2000), indicating that this group may constitute an interesting model for the study of the mechanisms involved in the process of speciation in fish.…”

“…However, for Neotropical fish of the order Siluriformes, only a few studies on nuclear DNA content are available and actually involve the data collected for no more than about 37 species (Carvalho et al, 1998). Nuclear DNA content values, associated to karyotypic information, are considered to be good indicators of the evolutionary process that occurs in Neotropical fish (Carvalho et al, 1998(Carvalho et al, , 2002. Thus, the objective of the present study was to analyze and compare information about the nuclear DNA content and the diploid number in 20 species of Siluriformes fish, in order to contribute to a better understanding of the diversification process that occurred in this group.…”

Genetic structure of the ornamental tetra fish species Piabucus melanostomus Holmberg, 1891 (CHARACIDAE, IGUANODECTINAE) in the Brazilian Pantanal wetlands inferred by mitochondrial DNA sequences

“…Published data only includes details of the haploid number (n = 25) in Iguanodectes spilurus Günther, 1864 (Scheel 1973), estimates of nuclear DNA content for P. melanostomus (Carvalho et al 2002) and a recent cytogenetic characterization in P. melanostomus (Silva et al 2011), the subject of this study.…”

Nuclear DNA content in Galaxias maculatus (Teleostei: Osmeriformes: Galaxiidae)

“…For G. maculatus, values of IOD of 199 individuals nuclei were determined. The IOD values were converted to absolute mass of DNA by comparison with erythrocyte smears of rainbow trout (Oncorhynchus mykiss, 2C = 5.5 pg, 2n = 58-60) (Hartley & Horne, 1985) a common standard to determine DNA content in fishes using flow cytometry (Tiersch et al, 1989) or Feulgen microdensitometry (Carvalho et al, 2002). The standard erythrocyte smears were included at the same staining runs and IOD estimations that the cells of G. maculatus.…”