The Study of Prolactin RsaI Polymorphism in Romanian Grey Steppe Cattle Breed

Abstract

SUMMARY Prolactin (PRL) is a protein hormone composed of 199 amino acids synthesized by the lactotrope cells from anterior pituitary gland. It is also produced in smaller quantities in other tissues, including mammary gland (Le Provost et al. , 1994). The gene coding for prolactin is located in cattle on the chromosome pair 23. Togeth er with growth hormone (GH), PRL stimulates mamogenesis, lactogenesis and galactopoesis (Carsai et al. , 2010). The increasing of blood prolactin concentrations during pregnancy leads to increasing of lactogen tissue growth, correlated after birth with an increased mi lk yield. Therefore is a valuable candidate gene for improving milk production in cattle and ot her species. In cattle several polymorphisms were described in PRL gene. Among these a silent A-G substitution from PRL exon three gives rise to a polymorphic Rsa I site (Lewin et al. , 1992) having an effect on milk production, although the results are conflicti ng (Chung et al. , 1996; Chrenek et al. , 1999; Dybus, 2002). The aim of our study was to determine the allelic and genotypes frequencies in PRL-Rsa I 3 rd exon site, in a primitive cattle breed with very l ow milk production, as is Romanian Grey Steppe breed. The amplification was performed with the primers described by Dybus et al. (2005) and the thermal cycling conditions as descr ibed by Carsai et al. (2011). The calculated allele frequencies were A=0.786; B=0.214 and the genotypes frequencies were: AA=0.571; AB=0.429; BB=0 (Fig. 1).