Mehmet NİZAMOĞLU, Ercan KURAR, Zafer BULUT

Türkiye'de bulunan bazı koyun ırklarının PrP lokus polimorfizmleri yönünden incelenmesi

Amaç: Bu çalışmanın amacı, Türkiye'de bulunan bazı yerli koyun ırklarında PrP lokusu 136., 154. ve 171. kodon polimorfizmlerinin belirlenmesidir.Gereç ve Yöntem: Akkaraman, Güney Karaman, Kangal Akkaraman, Dağlıç ve İvesi koyunlarından (n=175) örnekleme çalışması yapılmıştır. Kan örneklerinden standart fenol/ kloroform yöntemi kullanılarak genomik DNA izolasyonu gerçekleştirilmiştir. PrP bölgesi polimeraz zincir reaksiyonu (PZR) ile yükseltgenmiş, restriksiyon parça uzunluk polimorfizm (RFLP) analizi ile allel genotipleri tespit edilmiştir. Genel populasyon parametrelerinden allel sayısı (Na), gözlenen (Ho) ve beklenen (He) heterozigotluk değerleri ile Hardy- Weinberg Dengesinden (HWE) sapma değerleri hesaplanmıştır.Bulgular: Bütün populasyonlarda yüksek oranda A136R154Q171 genotipi tespit edilmiştir. Scrapie'ye en dirençli genotip olarak kabul edilen A136R154Q171 genotipi düşük (0.175-0.313) oranda gözlenmiştir. Ancak, hastalığa en duyarlı olan V136R154Q171 genotipine çalışmaya konu olan koyun ırklarında rastlanmamıştır. Bu çalışmada kullanılan koyun populasyonlarının Ulusal Scrapie Plan (NSP)'ına göre genel olarak R2 (dirençli) ve R3 (az dirençli) risk kategorilerinde yer aldığı tespit edilmiştir.Öneri: Bu ırkların ıslah programlarında PrP polimorfizmlerinin dikkate alınmasının ve scrapie dirençli genotiplerin frekanslarının artırılmasının uygun olacağı kanaatine varılmıştır.

Investigation of PrP locus polymorphisms in some native Turkish sheep breeds

Aim: The objective of this study was to investigate polymorphisms in codons 136, 154 and 171 of the PrP gene in native sheep breeds of Turkey.Materials and Methods: Sampling (n=175) was conducted from Akkaraman, Guney Karaman, Kangal Akkaraman, Daglic and Awassi breeds. Genomic DNA was isolated using a standard phenol/chloroform method. PrP region was amplified by polymerase chain reaction (PCR) and allele genotypes were determined by using restriction fragment length polymorphism (RFLP) analysis. General population parameters including allel numbers (Na), observed (Ho) and expected (He) heterozygosities and deviation from Hardy-Weinberg Equilibrium (HWE) were calculated.Results: High level of A136R154Q171 genotype was observed in all populations. A136R154Q171, which is known as the most resistant genotype to scrapie, was observed at lower (0.175-0.313) frequencies. However, V136R154Q171, the most susceptible genotype to the disease, was not determined in all investigated breeds. All sheep population investigated in this study were found to be generally in R2 (resistant) and R3 (little resistant) risc categories described in National Scrapie Plan (NSP).Conclusions: It is critically important to consider PrP polymorphisms and increase frequencies of scrapie resistant genotypes in breeding of these breeds.

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