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First description of microchromosome in the Anostomidae fish Schizodon nasutus from Argentina
M.C. Pastori; A.S. Fenocchio; P.A. López
Laboratorio de Citogenética General, Departamento de Genética, Facultad de Ciencias Exactas Químicas y Naturales. U.Na.M. Felix de Azara 1552.3300 Posadas, Misiones, Argentina. Send correspondence to M.C.P.
ABSTRACT
Thirty-six specimens of Schizodon nasutus (Anostomidae-Characiformes) from the middle Paraná River (Posadas, Argentina) were analyzed cytogenetically. The karyotype of this species was similar to those described for this species in the literature. C-banding technique showed a rich heterochromatic pattern relative to other Anostomidae species. The NORs were located on one chromosome pair in terminal position and showed a very marked size heteromorphism. A microchromosome was observed with a frequency of about 20% in the sample studied. This additional element was punctiform, negative C-band, and constant in all metaphase plates of the seven carriers. The present study is the first karyotypic approach to Schizodon nasutus from Argentina and the first description of microchromosome in Anostomidae.
Keywords: microchromosome; Anostomidae; Schizodon.
REFERENCES
Bertollo, L.A.C., Takahashi, C.S. and Moreira-Filho, O. (1978). Cytotaxonomic considerations on Hoplias lacerdae (Pisces, Erythrinidae). Rev. Bras. Genet. 1: 103-112.
Bertollo, L.A.C., Moreira Filho, O. and Galetti Jr., P.M. (1986). Cytogenetics and taxonomy: considerations based on chromosome studies of freshwater fish. J. Fish. Biol. 28: 153-159.
Foresti, F., Oliveira, C. and Almeida-Toledo, L.F. (1993). A method for chromosome preparations from large fish specimens using in vitro short-term treatment with colchicine. Experientia 49: 810-813.
Galletti Jr., P.M., Foresti, F. , Bertollo, L.A.C. and Moreira Filho, O. (1981). Karyotypic similarity in three genera (Leporinus, Leporellus and Schizodon) of the family Anostomidae (Pisces-Teleostei). Rev. Bras. Genet. 4: 11-15.
Galletti Jr., P.M., Foresti, F., Bertollo, L.A.C. and Moreira Filho, O. (1984). Characterization of eight species of Anostomidae (Cypriniformes) fish on the basis of the nucleolar organizing region. Caryologia 37: 401-406.
Galletti Jr., P.M., Mestriner, C.A., Venere, P.C. and Foresti, F. (1991). Heterochromatin and karyotype reorganization in fish of the family Anostomidae (Characiformes). Cytogenet. Cell Genet. 56: 116-121.
Guerra, M.S. (1986). Reviewing the chromosome nomenclature of Levan et al. Rev. Bras. Genet. 9: 741-743.
Howell, W.M. and Black, D.A. (1980). Controlled silver-staining of nucleolus organizer regions with a protective colloidal developer: a 1-step method. Experientia 36: 1014-1015.
Mestriner, C.A. (1993). Análise das regiões organizadoras de nucléolos e investigação do sistema XX/XY descrito para Leporinus lacustris (Pisces, Anostomidae). Master's thesis, Universidade Federal de São Carlos, São Carlos, SP, Brasil.
Oliveira, C. and Foresti, F. (1993). Occurrence of supernumerary microchromosomes in Steindachnerina insculpta (Pisces, Characiformes, Curimatidae). Cytobios 76: 183-186.
Oliveira, C., Almeida-Toledo, L., Foresti, F., Britski, H. and Toledo Filho, A. (1988). Choromosome formulae of Neotropical freshwater fishes. Rev. Bras. Genet. 11: 577-624.
Pauls, E. and Bertollo, L.A.C. (1983). Evidence for a system of supernumerary chromosomes in Prochilodus scrofa Steindachner,1881 (Pisces, Prochilodontidae). Caryologia 36: 307-314.
Pauls, E. and Bertollo, L.A.C. (1990). Distribution of a supernumerary chromosome system and aspects of karyotypic evolution in the genus Prochilodus (Pisces, Prochilodontidae). Genetica 81: 117-123.
Ringuelet, R.A., Aramburu, R.H. and Alonso de Aramburu, A. (1967). Los peces argentinos de agua dulce. Librart; Comisión de Investigación Cientifica, Provincia de Buenos Aires, La Plata, Argentina, pp. 209-212.
Salvador, L.B. and Moreira Filho, O. (1992). B-chromosOmes in Astyanax scabripinnis (Pisces, Characidae). Heredity 69: 50-56.
Sumner, A.T. (1972). A simple technique for demonstrating centromeric heterochromatin. Expl. Cell. Res. 75: 304-306.
Vari, R.P. (1983). Phylogenetic relationships of the families Curimatidae, Prochilodontidae, Anostomidae and Chilodontidae (Pisces, Characiformes). Smithson. Contrib. Zool. 378: 1-60.
Venere, P.C. (1991). Citogenética comparativa de peixes da família Curimatidae (Characiformes). Master's thesis, Universidade Federal de São Carlos, São Carlos, SP, Brasil.
Venere, P.C. and Galetti Jr., P.M. (1989). Chromosome evolution and phylogenetic relationships of some Neotropical Characiformes of the family Curimatidae. Rev. Bras. Genet. 12: 17-25.