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Cytogenetic study of Trichechus inunguis(Amazonian manatee)

M.F.L. Assis^I; R.C. Best^II; R.M.S. Barros^I; Y. Yonenaga-Yassuda^III

^IDepartamento de Genética, Centro de Ciências Biológicas, Universidade Federal do Pará, 66059 Belém, PA, Brasil. Send correspondence to M.F.L.A.
^IIFormer researcher at the Divisão de Mamíferos Aquáticos-INPA, Manaus, AM, Brasil
^IIIDepartamento de Biologia, Instituto de Biociências, Universidade de São Paulo, 05499 São Paulo, SP, Brasil

ABSTRACT

The chromosome constitution of the Amazonian manatee, Trichechus inunguis (Mammalia, Trichechidae) was studied in five male specimens and in four females originating from the Amazon basin, using standard Giemsa staining, G-, C- and NOR-banding. The diploid number of the species is 2n = 56, FN = 82. Constitutive heterochromatin is present in the centromeric region of all chromosomes and the nucleolar organizer genes are located on the secondary constriction of the short arm of pair 20, showing heteromorphic NOR staining between the two homologues. Comparative analysis of the karyotype. of T. inunguis with that of T. manatus studied by White et al. (1976) suggests that rearrangements of a Robertsonian type may be responsible for the karyotypic differences between these two species.

Keywords: cytogenetic; Trichechus inunguis.

REFERENCES

Bertram, G.C.L. and Bertram, C.K.R. (1973). The modern Sirenia: Their distribution and status. Biol. J. Linn. Soc., 5: 297-338.

Best, R.C. (1984a). The aquatic mammals and reptiles of the Amazon. In: The Amazon. Limnology and Landscape Ecology of a Mighty Tropical River and its Basin. (Sioli, H., ed.), W. Junk, Dordrecht, Boston, Lancaster. pp. 371-412.

Best, R.C. (1984b). Sea cows and manatees. In: The Encyclopaedia of Mammals. Vol. 1. (MacDonald, D., ed.) Unwin Animal Library. George Allen & Unwin, London, Sydney, pp. 292303.

Best, R.C. and Teixeira, D.M. (1982). Notas sobre a distribuição e "status" aparentes dos peixes-bois (Mammalia: Sirenia) nas costas amapaenses brasileiras. 1. B. FBCN - Rio de Janeiro 17: 41-47.

De Jong, W.W. and Zweers, A. (1980). Confirmação da relação entre peixes-bois, "hyraxes" e elefantes, por meio do estudo da proteína das lentes dos olhos. Acta Amazônica 10: 897-902.

Domning, D.P. (1981). Distribution and status of manatee Trichechus ssp. near the mouth of the Amazon river, Brazil. Brazil. Biol. Conserv. 19:85-97.

Ferrari, I., Casartelli, C., Peixoto, L.I. and Best, R.C. (1983). Análise citogenética do peixe-boi da Amazônia. Resumos da XXXV Reunião Anual da SBPC. p. 656.

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.

I.U.C.N. (1976). Red Data Book, Vol. 1, Mammalia. International Union for the Conservation of Nature and Natural resources, Morges, Switzerland.

Loughman, W.D., Frye, F.L. and Herald, E.S. (1970). The chromosomes of a male manatee, Trichechus inunguis. Int. Zoo Yearbook 10:151-152.

Miller, O.J., Miller, D.A., Dev, V.G., Tantravahi, R. and Croce, C.M. (1976). Expression of human and suppression of mouse nucleolus organizer activity in mouse-human somatic cell hybrids. Proc. Natl. Acad. Sci., USA. 73:4531-4535.

Seabright, M. (1971). A rapid technique for human chromosomes. Lancet 2: 971-972.

Sumner, A.T. (1972). A simple technique for demonstrating centromeric heterochromatin. Exp. Cell Res. 75: 304-306.

White, J.R., Harkness, D.R., Isaaks, R.E. and Duffield, D.A. (1976). Some studies on blood of the Florida manatee, Trichechus manatus latirostris. Comp. Biochem. Physiol. 55:413-417.

White, J.R., Harkness, D.R., Isaaks, R.E. and Duffield, D.A. (1977). Trichechus manatus latirostris (Manatee). Order: Sirenia. Family: Trichechidae. An Atlas of Mammalian Chromosomes. Vol. 10 (Hsu, T.C. and Benirschke, K., eds.).

Springer-Verlag, New York-Heidelberg-Berlin. Whitehead, P.J.P. (1978). Registros antigos da presença do peixe-boi do Caribe (Trichechus manatus) no Brasil. Acta Amazônica 8: 497-506.