Karyological Studies on Black Rat (Rattus rattus L.) from Bulgaria

Abstract

The black rat (Rattus rattus L.) from Bulgaria belongs to the Oceanian-type (n=38). Chromosomal analyses show that a polymorphism occurs in chromosomes nos. 9, 10 and 13 due to pericentric inversions. A polymorphism concerning size difference of centromeric heterochromatin (C-band) in some of the chromosomes is observed. The analyses of G-band patterns demonstrate that there are no differences between our material and the other black rats with 38 chromosomes. The NORs of the black rat (R. rattus) are found in telomeric regions of the short arms of chromosome pairs 3, 8, 13 and in telomeric region of the long arm of chromosome pair no. 10. A polymorphism due to supernumerary chromosomes is detected. The supernumeraries are metacentric and acrocentric. They show centromeric C-band after C-band staining.