Abstract
Chromosomes of Eigenmannia sp. (7 males and 15 females) collected from the Tietê River in Botucatu (SP, Brazil) were examined from gill, kidney and testicular cells. The diploid chromosome number in males was 2n=31 and in females, 2n=32. In both sexes the number of chromosomal arms was 40. The difference in diploid number was due to the fusion of two acrocentrics. Mitotic and meiotic studies suggested that one of the fused acrocentrics was the Y chromosome. The sex-determining mechanism in Eigenmannia sp. could therefore be XX, AA in the female and X, \-YA A in the males. One of the males presented 2n=30 chromosomes due to the occurrence of another fusion of acrocentrics. C-banding analysis of the mitotic chromosomes revealed constitutive heterochromatin in the centromeric regions of all acrocentrics. However, small metacentrics were C-band negative. The YA chromosome is C-band negative except for a small amount of heterochromatin in the centromeric region. The nucleolar organizer region as identified by Ag-staining is present in the interstitial region of chromosome pair No. 10.
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References
Almeida Toledo, L. F., 1978. Contribuição à Citogenetica des Gymnotoidel (Pisees, Ostariophysi). Ph.D. thesis, Instituto de Biociências da Universidade de São Paulo, S.P.
Almeida Toiedo, L. F., Foresti, F. & Toledo, F. S. A., 1981. Constitutive heterochromatin and nucleolus organizer region in the knifefish Apteronotus albifrons (Pisces, Apteronotidae). Experientia 37: 953–954.
Bertollo, L. A. C., Takahashi, C. S., Moreira Filho, O., 1978. Cytotaxonomic considerations on Hoplias lacerdae (Pisces, Erythrinidae). Rev. Bras. Genet. 1: 103–120.
Bertollo, L. A. C., Takahashi, C. S. & Moreira Filho, O., 1983. Multiple sex chromosomes in the genus Hoplias (Pisces: Erythrinidae). Cytologia 48: 1–12.
Foresti, F., Almeida Toledo, L. F. & Toledo, F. S. A., 1981. Polymorphic nature of nucleolus organizer regions in fishes. Cytogenet. Cell Genet. 31: 137–144.
Fredga, K., 1965. A new sex determining mechanism in a mammali chromosomes of Indian mongoose (Herpestes auropunetatus). Hereditas 52: 411–420.
Gold, J. R., 1979. Cytogenetics. In: Fish physiology, (eds W. S., Hoar, D. J., Randall & J. R., Brets). Vol. VIII, p. 353–405. Academic Press, New York and London.
Hayman, D. & Sharp, P., 1981. Verification of structure of the complex sex chromosome system in Lagorchestes conspicll-latus Gould (Marsupialia: Mammalia). Chromosoma 83: 263–274.
Howell, W. M. & Black, D. A., 1980. Controlled silver-staining of nucleolus organizer regions with a protective colloidal developer: a 1-step method. Experientia 36: 1014–1015.
Kligerman, A. D. & Bloom, S. E., 1977b. Rapid preparation from solid tissues of fishes. J. Fish. Res. Bd Canada 34: 266–269.
Kligerman, A. D. & Bloom, S. E., 1977b. Distribution of F-bodies, heterochromatin, and nucleolar organizers in the genome of the central mudminnow, Umbra limi. Cytogenet. Cell Genet. 18: 182–196.
Murofushi, M., Oikawa, S., Nishikawa, S. & Yoshida, T. H., 1980. Cytogenetical studies in fishes. III Multiple sex chromosome mechanism ion the filefish. Stephanolepis cirrhifer. Jap. J. Genet. 55: 127–132.
Park, E. H. & Grimm, H., 1981. Distribution of C-band heterochromatin in the ZW sex chromosomes of European and American cels (Anguillidae, Teleostomi). Cytogenet. Cell Genet. 31: 167–174.
Pathak, S. & Stock, A. D., 1976. Giemsa-banding and the identification of the Y-autosome translocation in the African marsh mongoose, Atilax paludinosus (Carnivera, Viverridae). Cytogenet. Cell Genet. 16: 487–491.
Pathak, S. The behavior of X chromosomes during mitosis and meiosis. In: ‘The cytogenetics of the mammalian X-chromosomes’. (ed. A.A. Sandberg). Alan R. Ziss, Inc. New York (in press).
Sumner, A. T., 1972. A simple technique for demonstrating centromeric heterochromatin. Expl Cell Res. 75: 304–306.
Thorgaard, G. H., 1978. Sex chromosomes in the sockeye salmon: A Y-autosome fusion. Can. J. Genet. Cytol. 20: 349–354.
Uyeno, T. & Miller, R. R., 1971. Multiple sex chromosomes in a Mexican cyprinodontid fish. Nature 231: 452–453.
Uyeno, T. & Miller, R. R., 1972. Second discovery of multiple sex chromosomes among fishes. Experientia 28: 223–225.
White, M. J. D., 1973. Animal cytology and evolution 3rd Ed. Cambridge University Press.
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De Almeida Toledo, L.F., Foresti, H. & De Almeida Toledo Filho, S. Complex sex chromosome system in Eigenmannia sp. (Pisces, Gymnotiformes). Genetica 64, 165–169 (1984). https://doi.org/10.1007/BF00115340
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DOI: https://doi.org/10.1007/BF00115340