Polymorphism of the melatonin receptor 1A (MNTR1A) gene and association with seasonality of reproductive activity in a local Greek sheep breed

Abstract

BackgroundSheep’s reproductive physiology in temperate latitudes (such as Greece), is characterized by seasonality and is also regulated by photoperiodic exposure. Melatonin is the key hormone involved in this regulation. However, the melatonin secretion and therefore the ewes reproductive activity underlies variation, proposed to be linked with the melatonin receptor subtype 1A (MNTR1A) gene structure. This study was designed to investigate the polymorphism of the MNTR1A gene in a local Greek sheep breed and to determine its potential association with reproductive seasonality.ResultsTwo groups of farmed ewes, each consisted of 30 individuals, were chosen. Males were introduced in both groups in spring (April). The first group consisted of ewes that showed reproductive activity in spring (May), while the second of ewes that showed reproductive activity 3 months later, in summer. The PCR–RFLP methodology was carried out on a 824-bp DNA fragment of the MTNR1A exon 2 using the RsaI restriction endonuclease. The electrophoretic procedure revealed three genotypes, C/C, C/T and T/T. Specifically, 44 animals showed the C/C genotype (28 from the first group and 16 from the second), 14 the C/T genotype (2 from the first and 12 from the second) and 2 animals had the T/T genotype (both from the second group).ConclusionsStatistical analysis indicated a positive correlation between genotype and reproductive seasonality, with C/C genotype playing a crucial role in out-of-season reproduction activity.

Genetic polymorphism in melatonin receptor 1A and arylalkylamine N-acetyltransferase and its impact on seasonal reproduction in Egyptian sheep breeds

“…However, in the Barki breed, the CC genotype was more frequent. The same result was reported by Giantsis et al (2016) in a local Greek sheep breed, Saxena et al (2015b) in the tropical sheep breeds of India, and Avanus and Altinel (2016) in Kıvırcık breed ewes. The TT homozygous genotype had the lowest frequencies in Ossimi and Rahmani and was not represented in the Barki breed, probably due to the low sample size.…”

“…Mura et al (2014) demonstrated that ewes carrying the CC and CT genotypes had significantly higher fertility rates and fewer days between the introduction of rams and parturition. Additionally, Giantsis et al (2016) reported that the CC genotype seemed to have an additive effect on sheep fertility with respect to out-of-season reproduction activity. Luridiana et al (2016) found that the CC genotype had a better response to melatonin treatment in Sarda sheep.…”

Polymorphisms of the melatonin receptor 1A gene that affects the reproductive seasonality and litter size in Small Tail Han sheep

“…Polymorphisms of MTNR1A gene have a great influence on the reproduction of goat (Carcangiu, Vacca, et al, ; Chu et al, ), cattle (Elraey et al, ), pig (Ramírez et al, ), goose (Alsiddig et al, ), buffalo (Gunwant et al, ; Jiang et al, ), chicken (Sundaresan et al, ) and sheep (Pelletier et al, , Chu, Ji, & Chen, , Chu et al, , Chu et al, , Mateescu et al, , Wang, , Lei, Di, Liu, & Chu, , Giantsis et al, , Calvo et al, ). The earliest researchers found two polymorphic loci in the 824bp of exon 2 of the MTNR1A gene in many sheep breeds using restriction endonucleases MnlI and RsaI (Messer et al, ; Notter, Cockett, & Hadfield, ).…”

“…MTNR1A , a receptor of melatonin, plays important roles in regulating the physiological rhythm and reproductive seasonality of mammals (Lei et al, ). Many researches indicated that polymorphisms of MTNR1A gene had effects on the reproductive seasonality in sheep (Calvo et al, ; Carcangiu, Mura, et al, ; Chu et al, ; Giantsis et al, ; Mateescu et al, ; Pelletier et al, ), goat (Carcangiu, Vacca, et al, ; Chu et al, ) and buffalo (Gunwant et al, ; Luridiana et al, ). MTNR1A is one potential candidate gene involved in the control of ovine reproductive seasonality.…”

“…In geese, the expression levels of MTNR1A initially increased and later decreased during the follicular development cycle, indicating that melatonin receptors participated in activating small white follicles and small yellow follicles to develop into subsequent greater hierarchical follicles (He et al, ). In sheep, most studies were centred on the positions of 606 and 612 in the MTNR1A gene exon 2, whose mutation could result in association with seasonal reproduction (Chu, Cheng, Liu, Fang, & Ye, ; Giantsis, Laliotis, Stoupa, & Avdi, ; Luridiana et al, ; Pelletier et al, ). Polymorphisms within the MTNR1A gene in the Sarda sheep breed, which exhibits an anoestrous period in late winter/spring, led to advances in reproductive resumption (Carcangiu, Vacca, et al, ).…”