Investigating the Polymorphism of TLR2 Gene and its Association with Somatic Cell Count in the Milk of Aleppo Goats Raised in Sanliurfa Province

Abstract

Mastitis is an important problem in the dairy industry which reduces milk yield and quality as well as causes economic loses. Somatic cell count (SCC) in milk is strongly associated to intra-mammary infections, thus represents an indicator of mammary health and milk quality. Toll-like receptor 2 (TLR2) is a member of of the Toll-like receptor family which is responsible for recognition of pathogens causing mastitis. Studies have shown that a 739G>A polymorphism in TLR2 gene is associated with SCC in milk in goat. This study aimed to determine the in the TLR2 gene (Toll-Like-Receptor 2) in Aleppo goats in Sanliurfa and to investigate whether there is a relationship between this polymorphism and somatic cell count (SCC) in milk. Milk samples (50 ml) were collected twice at one-month intervals from 100 goats in five farms raising Aleppo goats in Sanliurfa. The milk samples were used for DNA isolation and determination of SCC. The 442 bp region of the target TLR2 gene was amplified by PCR, and the PCR products were digested with the VspI enzyme and subjected to 2% agarose gel electrophoresis. Three genotypes, GG, GA, and AA, were observed in the entire sample. Of the 100 genotyped samples, 95 were GG, four were GA, and one was AA. The frequency of allele G was calculated as 0.97, and the frequency of allele A was calculated as 0.03. Mean SCC determined in milk samples from individuals carrying the A allele was found to be significantly lower. In conclusion, the G/A polymorphism of the TLR2 gene has a significant effect on SCC and this polymorphism can be used as a marker for selection purposes in breeding programs aimed at improving SCC and mastitis resistance in Aleppo goats.

Keywords

• Goat
• PCR
• polymorphism
• somatic cell count
• TLR2

Şanlıurfa İlinde Yetiştirilen Halep Keçilerinde TLR2 Genindeki Polimorfizm ve Sütteki Somatik Hücre Sayısı Arasındaki İlişkinin Araştırılması

Öz

Mastitis, süt endüstrisinde süt verimini ve kalitesini düşüren ve ekonomik kayıplara neden olan önemli bir sorundur. Sütteki somatik hücre sayısı (SCC), meme içi enfeksiyonlarla güçlü bir şekilde ilişkilidir ve bu nedenle meme sağlığı ve süt kalitesinin bir göstergesidir. Toll-like reseptör 2 (TLR2), mastitise neden olan patojenlerin tanınmasından sorumlu olan Toll-like reseptör ailesinin bir üyesidir. Araştırmalar, TLR2 genindeki 739G>A polimorfizminin keçi sütünde SCC ile ilişkili olduğunu göstermiştir. Sunulan bu çalışmada Şanlıurfa’daki Halep keçilerinde TLR2 genindeki (Toll-Like-Receptor 2) 739G>A polimorfizminin belirlenmesi ve bu polimorfizm ile sütteki somatik hücre sayısı (SHS) arasında ilişki olup olmadığının araştırılması amaçlanmıştır. Şanlıurfa’da Halep keçisi yetiştiren 5 işletmedeki 100 keçiden birer aylık arayla iki kez 50 ml süt örneği alındı. Süt örnekleri DNA izolasyonu ve SHS’nin belirlenmesi amacıyla kullanıldı. Hedef TLR2 geninin 442 bç’lik kısmı PCR işlemi ile çoğaltıldı ve VspI enzimi ile kesilen PCR ürünleri %2’lik agaroz jel elektroforezine tabi tutuldu. Tüm örneklem içerisinde GG, GA ve AA şeklinde üç genotip gözlendi. Genotiplenen 100 örnekten 95’inin GG, dördünün GA ve birinin ise AA genotipinde olduğu gözlendi. Allel G’nin frekansı 0.97, allel’nın A frekansı ise 0.03 hesaplandı. A allelini taşıyan bireylerin süt örneklerinde belirlenen ortalama SHS'nin önemli ölçüde daha düşük olduğu bulunmuştur. Sonuç olarak, TLR2 geninin G/A polimorfizmi SHS üzerinde önemli bir etkiye sahiptir ve bu polimorfizm Halep keçilerinde SCC ve mastitis direncini iyileştirmeyi amaçlayan ıslah programlarında seçim amaçlı bir belirteç olarak kullanılabilir.

Anahtar Kelimeler

• Keçi
• PCR
• polimorfizm
• somatik hücre sayısı
• TLR2

Kaynakça

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