Genomic analysis of arginine vasopressin gene in riverine buffalo reveals its potential association with silent estrus behavior.

Background: Poor estrus expression behavior causes suboptimal reproductive efficiency through poor conception rate. Various signaling pathways are involved in estrus expression but arginine vasopressin (AVP) gene with oxytocin predominantly regulates estrus behavior. This study aimed to perform genomic characterization and evolutionary dynamics of AVP gene through association testing of the novel polymorphic loci and comparative genomic analysis to explore the potential effect of AVP gene on estrus behavior of Nili-Ravi buffaloes.

Methods And Results: 198 Nili-Ravi buffaloes were screened for the quest of novel polymorphism in the AVP gene. In exon-1, five polymorphic sites were detected including deletion of two (c.47delA and c.57delA) nucleotides that caused drastic variation in subsequent amino acid sequence due to frame shift including functional short peptide of nine residues. The 3-D structure revealed a loss of transmembrane loop between 16 and 31 residues in Nili-Ravi buffalo AVP protein sequence, suggesting that missing loop apparently reduced the gene functionality in Nili-Ravi buffalo by inhibiting cellular reactions and muting the animal estrus cyclicity. Three polymorphisms detected in AVP gene were significantly associated with silent estrus (P < 0.05). The comparative genomic analysis revealed that AVP gene is present on chromosome 14 having one conserved motif (Neurohypophysial) in buffalo.

Conclusions: This study suggested the potential use of polymorphic sites as promising genetic markers for selection of buffaloes with pronounced estrus expression.