In this investigation, patterns of variation in the nucleolus organizer regions (NORs) in the chromosomes of Spalax leucodon and Spalax ehrenbergi were studied. The chromosomal location of the Ag-NORs was determined in two mole rat species. S. leucodon has 3 pairs of nucleolar chromosomes, but S. ehrenbergi has only 2 pairs of nucleolar chromosomes in their whole chromosome sets. | Tr. J. of Biology 23 (1999) 153-158 © TÜBİTAK Variation in the Nucleolus Organizer Regions (NORs) in Two Mole Rat Species (Spalax leucodon and Spalax ehrenbergi) Mehmet Doğan GÜLKAÇ Kocaeli University, Faculty of Medicine, Department of Medical Biology, 41900 Derince, KocaeliTURKEY İlknur (ŞENDOĞDU) KÜÇÜKDUMLU İnönü University, Graduate School of Technical and Natural Sciences 44069 Campus, Malatya-TURKEY Received: Abstract: In this investigation, patterns of variation in the nucleolus organizer regions (NORs) in the chromosomes of Spalax leucodon and Spalax ehrenbergi were studied. The chromosomal location of the Ag-NORs was determined in two mole rat species. S. leucodon has 3 pairs of nucleolar chromosomes, but S. ehrenbergi has only 2 pairs of nucleolar chromosomes in their whole chromosome sets. In both mole rat species, the chromosomal locations of Ag-NORs were determined to be on the terminal of the short arms of the subtelocentrics. The possibilty of Robertsonian translocation and the loss of paracentric NORs in S. ehrenbergi were discussed from an evolutionary point of view. Key Words: Nucleolus organizer regions (NORs), Spalax leucodon, Spalax ehrenbergi İki Kör Fare Türünde (Spalax leucodon ve Spalax ehrenbergi) Nukleolus Organizatör Bölge Varyasyonu Özet: Bu araştırmada, Spalax leucodon ve Spalax ehrenbergi kromozomlarında nukleolus organizatör bölge (NOR) varyasyonu araştırılmıştır. İki kör fare türünde Ag-NOR’un kromozomal yerleşimi tespit edilmiştir. S. leucodon 3 çift nukleolar kromozoma sahip iken S. ehrenbergi tüm kromozom takımında sadece 2 çift nukleolar kromozom içermektedir. Her iki kör fare türünde de, subtelosentrik kromozomların kısa kollarının terminalinde Ag-NOR yerleşimi tespit edilmiştir. Sonuçta, S. ehrenbergi’de Robertsonian translokasyonun ihtimali ve parasentrik NOR kaybı evrimsel açıdan tartışılmıştır. Anahtar Kelimeler: Nukleolus organizatör bölge (NOR), Spalax leucodon, Spalax ehrenbergi Introduction Extensive .
