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J. Biotec. Biodivers. v. 5, N.2: pp. 140-147 May 2014
Figure 1 - Geographical location of the Experimental Farm in the Federal University of Pampa, Dom Pedrito, RS, Southern Brazil: a) Geographical map of South America, showing in gray the country Brasil and in blue the State of Rio Grande do Sul; b) Geographic map of the State of Rio Grande do Sul; Source: ArcGis 10.1 and Google Earth.
Chromosome preparation
Short-term culture from kidney cells was performed in order to obtain metaphase chromosomes. The kidney was suspended in 10 ml of Hank's solution with 0.1 ml of 0.05% colchicine, followed by incubation at 37 °C for 1 hour. After this time, the suspension was centrifuged at 800 rpm for 8 min and the supernatant was removed. The pellet was resuspended in hypotonic KCl solution (0.075M, 10 ml) and incubated at 37 °C for more 30 minutes. Thereafter, the suspension was centrifuged at 800 rpm for 8 min and the supernatant discarded again. The pellet was fixed in methanol and acetic acid (3:1) and centrifuged for the same speed and time, this step was repeated three times.
Giemsa staining, Ag-NORs, GTG- and CBG-banding
To determine the diploid number, 50 metaphases were analyzed in 5% Giemsa staining . The
identification of constitutive heterochromatin
regions (CBG-banding) was performed according to Ledesma et al. (2002). To identify the chromosome pair carrying NORs it was used slides aged at 60 °C for 24 hours, subsequently it was done the silver staining according to the protocol of Howell and Black (1980). GTG- banding with trypsin was performed according to Seabright (1971).
RESULTS AND DISCUSSION
The karyotype of Mimus saturninus presents 2n=80, where the first and fourth pairs are submetacentric and the second, third and fifth are acrocentric, the other autosome chromosomes are telocentric. The Z sex chromosome is submetacentricand the W is metacentric (Fig. 2 a-b). This karyotype is typical of birds, which have a high diploid number (2n= among 78 and 80), a few pairs of macrochromosomes and many pairs of microchromosomes (Christidis 1990). The sex