Variable conservation of nucleolus organizer regions during karyotypic evolution in Microtidae.
The location of the nucleolus organizer regions (NORs) was studied in four species of Microtidae (Microtus nivalis, M. cabrerae, M. arvalis, and Arvicola sapidus). The comparative study of these locations shows that some NORs have been conserved despite the chromosome rearrangements that have occurred through karyotypic evolution, while others have been lost. In addition, there are many chromosomes in which NORs seem to have appeared or been lost without apparent relation to the chromosome rearrangements. Some hypotheses regarding these facts are discussed in the text.
Departamento de Biología Animal, Ecología y Genética, Facultad de Ciencias, Universidad de Granada, Spain.
A
A
Sánchez
M
M
Burgos
R
R
Jiménez
R
R
Díaz de la Guardia
D000818:Animals; D003411:Arvicolinae / Q000235:genetics*; D005075:Biological Evolution; D002871:Chromosome Banding; D015321:Gene Rearrangement; D007621:Karyotyping; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*