AÞAN BAYDEMÝR N., ALBAYRAK Ý., GÖZÜTOK S. 2011. Cytogenetic study on Microtus guentheri (Danford and Alston, 1880) (Mammalia: Rodentia) from Turkey: Constitutive heterochromatin distribution and nucleolar organizer regions. Folia biologica (Kraków) #': 35-40. Conventionally stained, C-and Ag-NOR banded karyotypes of Guenthers vole, Microtus guentheri were studied from Turkey. The species possesses a karyotype of 2n=54, NFa= 52 and NF=54 in specimens from Kahramanmaraº and Gaziantep provinces, whereas NF= 56 in females and NF=55 in males were found in individuals from Kýrýkkale and Nevþehir provinces. The X chromosome was a large acrocentric (NF=54) or submetacentric (NF=55, 56) while the Y chromosome was a small telocentric in all specimens examined. Blocks of constitutive heterochromatin were located in the pericentromeric areas of autosomes including the X chromosome. Nucleolar organizer regions (NORs) were located at the telomeric regions of the short arms of five acrocentric pairs and centromeric regions of two telocentric pairs in the Nevþehir and Kýrýkkale specimens.

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-In this study, conventionally stained, C-and Ag-NOR banded karyotypes of Dahl's jird, Meriones dahli, were reported from Turkey. The species had a karyotype of 2n = 50, NFa = 74 and NF = 78. The X and Y chromosomes were submetacentrics in all specimens examined. Blocks of constitutive heterochromatin were located in the pericentromeric areas of autosomes including the X and Y chromosomes. Interstitial C-bands are also detected in the long arms of one of the largest acrocentric pairs. Nucleolar organizer regions (NORs) were located at the telomeric regions of the short arms of three submetacentrics and two acrocentrics.

In this study, the G-bands and nucleolus organizer regions (NORs) of the 2n = 60 chromosomal form of Nannospalax nehringi from Central Anatolia (Konya) are presented. The karyotype possesses nine pairs of submetacentric and subtelosentrics and 20 pairs of acrocentric autosomes gradually decreasing in size (fundamental number = 80 and autosomal fundamental number = 76). NORs were localized in the telomeric regions of the short arms of three large pairs and one medium-sized pair of subtelocentric autosomes (nos. 1, 3, 4, 9).

In this study, conventionally stained, C-and Ag-NOR banded karyotypes of Rattus rattus from Central Anatolia are presented. The karyotype of the specimens from Ankara and Çankýrý provinces consist of 2n=38, NF= 60 and NFa=58 while the karyotype of Kýrýkkale specimens consist of 2n=38 and NFa=59 due to a heteromorphic autosome pair. The X is a large to medium sized acrocentric and the Y chromosome is a small acrocentric in all examined specimens. Constitutive heterochromatin is located in the centromeric regions of all pairs of autosomes and the X chromosome. Nucleolar organizer regions (NORs) are located only in 3 autosome pairs.