Abstract
Chromosomes were analyzed in 91 specimens ofNectomys squamipes, collected in three distinct geographic regions of Brazil. Chromosomal polymorphism due to supernumerary chromosomes, Robertsonian rearrangement and variation of sex chromosomes is reported. Samples collected in the northeastern region had 2n=52, FN=52; 2n=53, FN=54; 2n=54, FN=56; 2n=55, FN=56; 2n=56, FN=56; 2n=57, FN=57. The specimens from the southeastern and southern regions showed 2n=55, FN=56; 2n=56, FN=56; 2n=57, FN=58; 2n=58, FN=60; 2n=59, FN=62. Seven different types of supernumeraries were observed. These vary in size, morphology and C-banding characteristics.
The Brazilian populations ofNectomys squamipes are composed of at least two basic entities, one with 2n=52 and its increasing series up to 2n=55, the other with 2n=56, increasing to 2n=59. Both entities are characterized by variation from 0 to 3 supernumeraries. The X and Y chromosomes present polymorphisms in terms of the size, shape as well as the distribution of constitutive heterochromatin.
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References
Baverstock, P. R., Gelder, M. & Jahnke, A., 1982. Cytogenetic studies of the Australian rodent Uromys caudimaculatus, a species showing extensive heterochromatin variation. Chromosoma 84: 517–533.
Baverstock, P. R., Watts, C. H. S. & Hogarth, J. T., 1976. Heterochromatin variation in the Australian rodent Uromys caudimaculatus. Chromosoma 57: 397–403.
Baverstock, P. R., Watts, C. H. S. & Hogarth, J. T., 1977a. Chromosome evolution in Australian rodents. I. The Pseudomyinae, the Hydromyinae and the Uromys/Melanomys group. Chromosoma 61: 95–125.
Baverstock, P. R., Watts, C. H. S., Hogarth, J. T., Robinson, A. C. & Robinson, J. F., 1977b. Chromosome evolution in Australian rodents. II. The Rattus group. Chromosoma 61: 227–241.
Bekasova, T. S., Vorontsov, N. N., Korobitsyna, K. V. & Korablev, V. P., 1980. B-chromosomes and comparative karyology of the mice of the genus Apodemus. Genetica 52/53: 33–43.
Blanks, G. A. & Shellhammer, H. S., 1968. Chromosome polymorphism in Californian populations of harvest mice. J. Mammal. 49: 726–731.
Cabrera, A., 1961. Catalogo de los mamiferos de America del Sur. Revta Mus. argent. Cienc. nat. 6: 309–732.
Ford, C. E. & Hamerton, J. L., 1956. A colchicine hypotonic-citrate squash sequence for mammalian chromosome. Stain Techn. 31: 247–251.
Gardner, A. L. & Patton, J. L., 1976. Karyotypic variation in oryzomyine rodents (Cricetinae) with comment on chromosomal evolution in the Neotropical Cricetine complex. Occ. Pap. Mus. Zool. 49: 1–48.
Gileva, E. A., 1973. B-chromosomes, unusual inheritance of sexual chromosomes and sex ratio in lemming Dicrostonyx torquatus. Dokl. Acad. Nauk SSSr 213: 952–955.
Gropp, A., Marshall, J. & Markvong, A., 1973. Chromosomal findings in the spiny mice of Thailand (genus Mus) and occurrence of a complex intraspecific variation in Mus shortridgei. Z. Säugetierk. 38: 159–168.
Gropp, A. M., Olbricht, A., Santadutsi, K., Manyanondha, G., Platz, J. & Marshall, I., 1970. Chromosomes of the house rat Rattus rattus; findings in an Asiatic population. Mamm. Chrom. Newsl. 11: 111–112.
Hayata, I., 1973. Chromosome polymorphism caused by supernumerary chromosomes in the field mouse, Apodemus giliacus. Chromosoma 42: 403–414.
Patton, J. L., 1977. B-chromosome system in the pocket mouse, Perognathus baileyi: meiosis and C-bands studies. Chromosoma 60: 1–14.
Popescu, C. P., 1975. L'étude du caryotype bovin (Bos taurus) par les méthodes des bandes. Annls Biol. anim. Biochim. Biophys. 15: 751–756.
Pretel, M. A. & Diaz de la Guardia, G. R., 1978. Chromosomal polymorphism caused by supernumerary chromosomes in Rattus rattus ssp. frugivorus (Rafinesque, 1814) (Rodentia, Muridae). Experientia 34: 325–328.
Raman, R. & Sharma, T., 1974. DNA replication, G- and C-bands, and meiotic behaviour of supernumerary chromosomes of Rattus rattus (Linn.). Chromosoma 45: 111–119.
Seabright, M., 1971. A rapid banding technique for human chromosomes. Lancet 2: 971–972.
Shellhammer, H. S., 1969. Supernumerary chromosomes of the harvest mouse, Reithrodontomys megalotis. Chromosoma 27: 102–108.
Sumner, A. T., 1972. A simple technique for demonstrating centromeric heterochromatin. Expl Cell Res. 75: 304–306.
Yonenaga, Y., Frota-Pessoa, O., Kasahara, S. & Almeida, E. J. C., 1976. Cytogenetic studies on Brazilian rodents. Cienc. Cult. 38: 202–211.
Yosida, T. H., 1977. Supernumerary chromosomes in the black rat (Rattus rattus) and their distribution in three geographic variants. Cytogenet. Cell Genet. 18: 149–159.
Zimmerman, E. G., 1970. Karyology, systematics and chromosome evolution in the rodent genus Sigmodon. Publs Mich. St. Univ. Mus. 4: 384–454.
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This research was supported by CNPq-PIG (Projeto Integrado de Genética) and is part of the Rodent Cytogenetic Colaborative Study, developed by different Laboratories in Brazil.
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Maia, V., Yonenaga-Yassuda, Y., Freitas, T.R.O. et al. Supernumerary chromosomes, Robertsonian rearrangement and variability of the sex chromosomes inNectomys squamipes (Cricetidae, Rodentia). Genetica 63, 121–128 (1984). https://doi.org/10.1007/BF00605896
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DOI: https://doi.org/10.1007/BF00605896