A novel deleterious oxytocin variant is associated with the lower twinning ratio in Awassi ewes

Abstract

This study aimed to assess the possible association of oxytocin (OXT) gene with reproductive traits in two groups of Awassi ewes that differ in their reproductive potentials. Sheep were genotyped using PCR—single-stranded conformation polymorphism approach. Three genotypes were detected in exon 2, CC, CA, and AA, and a novel SNP was identified with a missense effect on oxytocin (c.188C > A → p.Arg55Leu). A significant (p < 0.01) association of p.Arg55Leu with the twinning rate was found as ewes with AA and CA genotypes exhibited, respectively a lower twinning ratio than those with the wild-type CC genotype. The deleterious impact of p.Arg55Leu was demonstrated by all in silico tools that were utilized to assess the effect of this variant on the structure, function, and stability of oxytocin. Molecular docking showed that p.Arg55Leu caused a dramatic alteration in the binding of oxytocin with its receptor and reduced the number of interacted amino acids between them. Our study suggests that ewes with AA and CA genotypes showed a lower reproductive performance due to the presence of p.Arg55Leu, which caused damaging impacts on oxytocin and is binding with the OXT receptor. The utilization of the p.Arg55Leu could be useful for improving Awassi reproductive potential.

Keywords:

• Hormone
• OXT
• polymorphism
• reproductive performance
• sheep

Acknowledgments

The authors thank the breeders of Barakat Abu al Fadhl Al-Abbas Station for raising sheep (Al-Khafeel co., Holy Karbala, Iraq) for providing all necessary facilities during animal experimental procedures. This work was a part of the Ph.D. thesis of N.M.K. prepared in the College of Agriculture, Al-Qasim Green University, in collaboration with the College of Veterinary Medicine, University of Baghdad (Decision no. 1274, on 21 June 2021).

Author contributions

N.M.K. performed the main lab work. H.F.A. designed and supervised the study. M.B.S.A. co-supervised the study, performed the genetic analysis, and wrote the manuscript. T.M.A. analyzed the statistical data and participated in lab work. A.H.A. participated in the lab work. All authors approved the final manuscript for publication.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was not receiving any funds from any institution or funding agency.