Genetic polymorphism of growth differentiation factor 9 (GDF9) gene related to fecundity in two Egyptian sheep breeds.

Purpose: This study explores polymorphisms in the growth differentiation factor 9 (GDF9) gene (exon 1) with respect to fertility in Egyptian sheep.

Methods: Blood samples were collected, and genomic DNA was extracted from 24 Saidi and 13 Ossimi ewes. A 710 bp portion of the GDF9 gene, was amplified using specific primers, and the sequence was analyzed to clarify the phylogenetic relationship of Egyptian breed sheep. In addition, the PCR-RFLP method using Pst1 or Msp1 restriction enzymes was used to mask polymorphisms of partial exon 1 of GDF9 gene to establish molecular markers for twinning.

Results: The lambing rate percentage and litter size showed significant difference between ewes, which produce single and twin lamb for each breed individually, whereas the coefficient of variation of the Saidi breed is greater than that of the Ossimi breed. The results suggested that the GDF9 gene shared a similarity in sequence compared to six accession numbers of Ovis aries found in GenBank. Molecular phylogenetic analyses were performed based on nucleotide sequences in order to examine the position of the Egyptian breeds among many other sheep breeds. The results indicate that accession number AF078545 of O. aries is closely related with Saidi and Ossimi ewes that produce single or twin lamb using the unweighted pair group method with arithmetic mean (UPGMA) analysis. Results showed that Msp1 enzyme digestion revealed polymorphic restriction pattern consisting of one band with 710 bp for ewes producing single lamb and two bands with 710 and 600 bp for ewes producing twin lamb in Saidi sheep breed.

Conclusion: Sequence analysis and diversity of polymorphisms in the GDF9 gene (exon 1) have a novel base substitution (A-T) for detection of Fec mutations that serve as a molecular marker for twinning.