Supernumerary chromosomes in the pufferfish Sphoeroides spengleri: first occurrence in marine Teleostean Tetraodontiformes fish

Anderson Luis Alves,Claudio Oliveira,Fausto Foresti,Fábio Porto-Foresti

doi:10.1590/s1415-47572008000200014

Anderson Luis Alves, Claudio Oliveira + Show 2 more

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https://doi.org/10.1590/s1415-47572008000200014

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Abstract

Cytogenetic analyses carried out in eight specimens of Sphoeroides spengleri revealed the presence of 2n = 46 chromosomes (20 M/SM and 26 ST/A). Besides the standard karyotypical set, the presence of B microchromosomes was observed in two individuals, ranging from 0 to 2 microchromosomes per cell. A karyotype composed by 2n = 46 chromosomes with occurrence of M and SM chromosomes is considered basal for the species from the clade comprising the families Tetraodontidae, Balistidae, and Diodontidae, although it represents a derived condition for the order Tetraodontiformes, whose basal karyotype would be composed by 2n = 48 acrocentric chromosomes. The occurrence of B microchromosomes in marine Tetraodontiformes fish was not known, and this represents the first report of such a chromosomal type.

Highlights

The order Tetraodontiformes comprises nearly 340 species, divided into five families (Nelson, 1994)
The occurrence of supernumerary chromosomes in Neotropical fishes seems to be a common event in freshwater species, previously reported in 41 of the 921 analyzed species (Oliveira et al, 2000), characterized by the presence of B microchromosomes (Alves and Martins-Santos, 2002) or B macrochromosomes (Porto-Foresti et al, 1997)
The cytogenetic analyses were performed in eight specimens (3 females, 4 males, and 1 sex undetermined individual) of S. spengleri collected at Ubatuba Bay, São Paulo, Brazil

Summary

Introduction

The order Tetraodontiformes comprises nearly 340 species, divided into five families (Nelson, 1994). The diploid number in Tetraodontiformes ranges from 2n = 28 in Canthigaster coronata (Arai, 1983) to 2n = 52 in Chilomycterus spinosus (Brum, 2000), suggesting that this group is not karyotypically conserved. The diploid number of 2n = 46 observed in the Sphoeroides species previously surveyed (Brum and Mota, 2002) is considered the basal karyotype for the more derived Tetraodontiformes: Tetraodontidae, Balistidae, and Diodontidae (Arai, 1983; Brum, 2000; Galetti et al, 2006).

Results

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