Effect of leptin, gene, polymorphism, on reproductive efficiency in awassi ewes

IntroductionLeptin (LEP), is a protein hormone,released mostly from adipose tissue, its regulate GnRH, prevents reduction of pulsatile LH throughout fasting , and control of reproduction in ewes.ObjectiveStudy performed to identify the linkage between LEP, gene polymorphism, and reproductive efficiency such as seasonality and litter size.MethodsForty mature non-pregnant Awassi ewes were utilized between 1st July/2017 to 1st May/2018. Twenty ewes were demonstrated estrus heat at August/2017where it was considered seasonal group and the others showed estrus signs at April/2018, which considered non-seasonal group. Genomic DNA was extracted from blood specimens and four primers were utilized to amplify exon II, intron II and exon III of LEP gene.Polymorphisms were revealed via sequencing and compared with the sequencing of ovine LEP gene in NCBI.ResultsOne SNP A(99)R was detected in intron II and three SNPs G(425)R, T(541)K and G(587)R were in exon III. Two genotypes of each SNP were observed with higher significant differences (P<0.01) between frequencies 47.50 and 52.50 for AA and AG of A(99)R, 42.50 and 57.50 for GG and GA of G(425)R, 55.00 and 45.00 for TT and TC of T(541)K, lastly, 37.50, 62.50 for GG and GA of G(587)R. The finding demonstrated AG genotypic frequency of non-seasonal ewes (55.00) was significantly increased (P<0.05) than AA (45.00) for A(99)R SNPs. The GA, TC and GA genotypic frequencies (80.00, 40.00 and 85.00) were recorded higher significant increased (P<0.01) than GG, TT and GG (20.00, 60.00 and 15.00) for G(425)R, T(541)K and G(587)R SNPs in non-seasonal group. Higher significant increased (P<0.01) were observed in GG, TT and GG genotypic frequencies (65.00, 70.00 and 60.00) than GA, TC and GA (35.00, 30.00 and 40.00) for G(425)R, T(541)K and G(587)R SNPs respectively in seasonal group, while non-significant differences were observed between AA and AG (50.00 for each) genotypic frequency for A(99)R SNPs of seasonal group. Non-significant differences in litter size were recorded between GA (1.39) and GG (1.29) for G(425)R and between GG (1.4) and GA (1.32) for G(587)R, while significant differences (P<0.05) were observed between AG (1.26) and AA (1.42) and between TT (1.18) and TC (1.55) for A(99)R and T(541)K respectively.ConclusionsIn Awassi breed, exon III polymorphisms of LEP gene have an expected effect on the seasonality and the wild genotypes find majorly in seasonal ewes. Intron II and exon III polymorphisms (2 SNPs) caused an increment in litter size

Keywords:

Leptin , Polymorphism , Reproduction , Litter size