Mansooreh Rajaei Nejad - Department of Animal Science, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran.
Ahmad Ayatollahi Mehrgardi - Department of Animal Science, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran.
Vahideh Rezaei - Department of Animal Science, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran.
Ali Esmailizadeh - Department of Animal Science, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran.

This study was carried out to investigate the polymorphisms of bone morphogenetic protein ۱۵ (BMP۱۵) exon ۲ in purebred Kermani and crossbred Romanov × Kermani sheep and functional analysis of the underlying mutations. A number of ۵۰ purebred Kermani and ۱۱۵ F۱ Romanov (ram) × Kermani (ewe) crossbred sheep were sampled and a ۱۵۳ bp fragment from exon ۲ of the ovine BMP۱۵ gene was successfully amplified from the genomic DNA of each animal using designed primers. The polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) technique was used to investigate the polymorphism of BMP۱۵ gene (exon ۲(. Twenty samples of different SSCP patterns were randomly selected for DNA sequencing and detecting the BMP۱۵ mutations and subsequent functional analyses. The polymorphic fragments amplified by designed primers were sequenced. There were eight SSCP patterns (AA, AB, BB, AC, AD, AE, AF and AG) with frequencies of ۰.۲۴, ۰.۱۷, ۰.۲۴, ۰.۰۸, ۰.۰۵, ۰.۱۰, ۰.۰۳ and ۰.۰۹, respectively. The frequency of A allele was obviously higher than those of other alleles. The sequencing results revealed two single nucleotide mutations; the first mutation at position ۳۲bp which did not cause any change in the amino acid sequence but the second mutation led to a change in ۴۰th amino acid (a Lysine amino acid replaced by an Asparagine amino acid). The result of this experiment indicates that the genetic diversity level of BMP۱۵ exon ۲ gene was high in the Romanov × Kermani crossbreds indicating that BMP۱۵ exon ۲ can played a vital function in the development of ovary and follicles, especially in the improvement of fertility trait and could be used as a potential advantageous molecular marker for reproduction traits in this genetic group. Our finding provides exciting new opportunities for understanding the role of the BMP۱۵ on ovarian follicular growth and development in crossbreed ewes in breeding programs.  However, further investigation using a large population of Romanov × Kermani crossbred sheep is required to confirm the link between the identified mutation and the observed increased prolificacy in this population.

BMP۱۵, PCR-SSCP, polymorphism, Romanov × Kermani sheep