III. International Agricultural, Biological & Life Science Conference, Edirne, Turkey, 1 - 03 September 2021, vol.1, pp.123
Leptin is a 16 KD protein and is encoded by the leptin (LEP) gene. LEP has been demonstrated to be significantly associated with the regulation of appetite and energy metabolism in mammals, and therefore, it has been shown to be a significant genetic marker regarding feed intake, body weight, growth rate, and fat deposition. Based on these essential impacts of the gene, it has been widely studied to evaluate its association with meat and milk production. On the other hand, the role of the LEP on reproductive performance such as puberty, litter size, spermatogenesis, maturation, capacitation, and the motility of sperm has been reported. Ovine LEP is located on chromosome 4 and it consists of three exons and two introns. Although the gene’s effects were well-characterized in cattle, information on the LEP in small ruminants is relatively limited. Moreover, there is no publicly available report about the LEP g.332G>A mutation in Turkish native sheep breeds. Therefore, the objective of this study was to analyze the genotypic distribution and population genetic characteristics of the g.332G>A mutation located on exon 3 of ovine LEP gene in Kıvırcık sheep. A total of 91 animals were used in the present study. DNA isolation was performed using the phenol-chloroform method and the PCR-RFLP procedure was applied for the genotyping. A 463 bp fragment was amplified using 5´-TGTTGTCCCCTTCCTCCTG-3´ and 5´-CCCACATAGGCTCTCTTCTGC-3´ sequences as the forward and reverse primers, respectively. The amplicons were digested by the AlwNI restriction nuclease. The genotypic and allelic frequencies expected/observed, and Nei’s heterozygosities (He) were calculated, and Hardy-Weinberg Equilibrium (HWE) was tested by chi-square test. The effective allele numbers (Ne), polymorphism information content (PIC), and the fixation index (FIS) were estimated using appropriate formulas. The Shannon-Weaver diversity index (H´) was also calculated. Results revealed that the heterozygous genotype was predominant in the Kıvırcık breed. In this respect, 41 sheep were genotyped as the GA (45%). The AA genotype frequency was considerably low (13%) resulting in low frequency (36%) of the A allele. The distributions of genotypes agreed with HWE within the LEP marker. Population genetic parameters indicated that the LEP g.332G>A is a mildly informative marker for the Kıvırcık sheep breed. In this context, PIC and Ne values were found to be 0.3546 and 1.8546, respectively. FIS was calculated as 0.1102. He was 0.4608 and the H’ was estimated at 0.6534. Thus LEP g.332G>A showed an admissible diversity in the Kıvırcık breed. This sheep breed is one of the most important native livestock genetic resources of Turkey. It is a thin-tailed breed, and its meat is preferred widely by the consumer because of superior meat quality characteristics. Unconscious crossbreeding and importation have resulted in a decrease or loss of diversity on Turkish native sheep breeds without characterization. This has also resulted in difficulties in finding purebred individuals. This study focused on the population genetic properties of the g.332G>A mutation in the ovine LEP gene. The present results showed that the selected marker exhibited a non-objectionable variation in Kıvırcık sheep to consider it in genetic association studies. However, analyzes with larger sample sizes are needed. To the best of the author's knowledge, this is the first report about the genetic variability of the LEP g.332G>A mutation in the Kıvırcık breed. Thus, the results may be useful and informative for further detailed analyzes.