No abstract

The interleukin-4 (IL-4) and interleukin-4 receptor (IL-4R) are cytokines that are involved in the immune and reproductive systems. This study aimed to verify the polymorphisms in the porcine IL-4 and IL-4R genes and to assess their effects on litter size traits in commercial pigs. Single nucleotide polymorphisms (SNPs) in the porcine IL-4 and IL-4R genes were genotyped by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. A non-coding SNP of IL-4 g.134993898T > C and a non-synonymous SNP of IL-4R c.1577A > T (amino acid change at position 526, Q526L) were found to be segregating in Landrace sows. The IL-4 g.134993898T > C polymorphism was significantly associated with the number of piglets weaned alive (NWA) trait. The IL-4R c.1577A > T polymorphism was significantly associated with the number born alive (NBA) and NWA traits. Moreover, the accumulation of favorable alleles of these two SNP markers revealed significant associations with the NBA, NWA, and mean weight of piglets at weaning (MWW) traits. These findings indicate that the porcine IL-4 and IL-4R genes may contribute to the reproductive traits of pigs and could be used as candidate genes to improve litter size traits in the pig breeding industry.

Interleukin-17 receptor A (IL17RA) is one of the cytokine receptors of the pro-inflammatory interleukin-17 (IL17) cytokine family. The IL17 and IL17RA genes are involved in inflammatory and immune responses as well as reproductive process of mammals. The purposes of this study were to examine polymorphisms in the porcine IL17RA gene and to assess its effects on litter size traits in Large White and Landrace pigs. Three non-synonymous single nucleotide polymorphisms (SNPs) in the porcine IL17RA gene were verified. The porcine IL17RA c.785C>T (p.Ala262Val) was found to be segregating in the Large White and Landrace pigs. No polymorphisms in the coding region of the porcine IL17RA gene at the two non-synonymous SNPs loci of c.997G>A (p.Val333Ile) and c.1962T>G (p.Asp654Glu) were found. The porcine IL17RA c.785C>T polymorphism was significantly associated with the total number born (TNB) and the number born alive (NBA) in Large White pigs (P<0.05). Moreover, the porcine IL17RA c.785C>T was significantly associated with the TNB, NBA, total birth weight (TBW), and total weaning weight of piglets at 21 days (TWW) in Landrace pigs (P<0.05). These results supported the importance of the porcine IL17RA gene in the litter size traits of pigs. Thus, the porcine IL17RA could be used as a potential candidate gene for improving litter size traits in pig breeding.

Leukemia inhibitory factor (LIF) is a crucial candidate gene that impacts on implantation process. In this study, the effects of the porcine LIF polymorphism on litter size traits were elucidated in Thai commercial pig populations. Genotyping of three single nucleotide polymorphisms (SNPs) of the porcine LIF gene was detected in coding and 3ˊ-untranslated regions. The porcine LIF c.*24C>T was segregating in Large White, Landrace, and Large White × Landrace (LW × LR) crossbred sows. No polymorphisms at two non-synonymous SNPs loci (LIF c.28C>A and LIF c.161A>G) were found in this study. The porcine LIF c.*24C>T was significantly associated with the total number born (TNB), the number born alive (NBA), and the number of piglets weaned alive (NWA) traits in Large White and Landrace sows. Moreover, the porcine LIF c.*24C>T was associated with the NBA and NWA traits in LW × LR crossbred sows. The favorable LIF c.*24C allele was positively correlated with the litter size traits. These findings indicated that the polymorphism of the porcine LIF gene was associated with litter size traits and confirms the significance of porcine LIF as a candidate gene for litter size traits in pig breeding. Thus, the porcine LIF gene could be used for improving prolific traits in these Thai commercial pig populations.

The objectives of this study were to verify the polymorphism on sex-linked marker loci and to assess their associations with phenotypic sex characteristics in red tilapia. Four sex-linked genetic markers of Amh, SCAR4, SCAR5, and Oni3161 were genotyped in the Thai red tilapia population. The Amh marker was significantly associated with the phenotypic sex of red tilapia with an accuracy of 46.2%. No significant association of SCAR4, SCAR5, and Oni3161 marker polymorphisms with phenotypic sex characteristics was observed in this study. However, the combinations of these two, three, and four markers were increasingly associated with phenotypic sex characteristics for red tilapia with an accuracy of 62.8, 68.4, and 72.4%, respectively. These results indicate that these combined genetic markers were associated with the phenotypic sex of red tilapias. These findings confirmed the importance of these genetic markers as candidate markers for sex determination in the Thai red tilapia population.

Osteopontin (OPN) is a secreted phosphoprotein that is involved in the development of skeletal muscle and fat deposition. The objectives of this study were to identify the polymorphism of the OPN gene and to analyze the association of the OPN gene with intramuscular fat (IMF) content and fatty acid (FA) composition in pigs. Longissimus thoracis (LT) muscle samples taken from the 10-11th rib were collected from a total of 328 Duroc pigs. Genomic DNA samples were extracted from LT muscle tissues using the phenol-chloroform method. IMF content was measured using the ether extraction method and FA composition was measured by gas chromatography. The porcine OPN polymorphisms were identified by DNA sequencing and were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The association analysis of the OPN gene with IMF and FA composition traits was performed using a general linear model (GLM). Two polymorphic sites (OPN g.2442-2471indel and g.3836A>G) were found in the 5´-flanking region and intron 1 of the porcine OPN gene. The OPN g.2442-2471indel polymorphism was found to be significantly associated with IMF content and ω3 FA levels (P<0.05). Moreover, OPN g.3836A>G polymorphism was significantly associated with the linolenic acid levels in the muscles of pigs (P<0.05). The results of this study indicate that the OPN gene is important to IMF content, as well as linolenic and ω3 FA levels in pigs, and could be used as a candidate gene to improve fat deposition and fatty acid composition in the muscles of pigs.

This study aimed to verify the polymorphisms in the porcine IL-6 gene and to elucidate its effects on litter size traits in Large White and Landrace sows. Four single nucleotide polymorphisms (SNPs) of the porcine IL-6 gene (g.91506415A>G, g.91507983A>G, g.91508173C>T, and g.91508716C>T) were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. There was no polymorphism observed on the three SNPs (g.91506415A>G, g.91507983A>G, and g.91508716C>T) of the porcine IL-6 gene. The porcine IL-6 g.91508173C>T polymorphism was found to be segregating in Large White and Landrace sows. The porcine IL-6 g.91508173C>T polymorphism was significantly associated with the total number born (TNB) and the number of piglets weaned alive (NWA) traits in Large White sows (P<0.05). Moreover, the porcine IL-6 g.91508173C>T polymorphism was significantly associated with the TNB, number born alive (NBA), and NWA traits in Landrace sows (P<0.05). These results indicated that the porcine IL-6 g.91508173C>T polymorphism was associated with litter size traits. These findings confirmed the importance of the IL-6 gene as a candidate gene for litter size traits in pigs.

Ferritin heavy chain (FTH) and erythropoietin receptor (EPOR) are responsible for the iron homeostasis and the erythropoiesis that correlate to the reproductive systems. This study aimed to examine an association of the porcine FTH and EPOR genes with litter size traits in Large White and Landrace pigs. The porcine FTH g.9537834G > A was significantly associated with the total number born (TNB) trait in these pig populations (p < 0.05). The porcine FTH g.9537855T > C was significantly associated with the TNB trait in Large White sows (p < 0.05) as well as the TNB and the number of birth alive (NBA) traits in Landrace sows (p < 0.05). The porcine EPOR g.70066473C > T was significantly associated with the TNB trait in Large White sows (p < 0.05) as well as the TNB, NBA, and the number of piglets weaned alive (NWA) traits in Landrace sows (p < 0.05). Moreover, the accumulated favorable alleles of these three SNPs were increasingly associated with TNB trait in Large White sows (p < 0.05) and TNB, NBA, and NWA traits in Landrace sows (p < 0.05). These findings suggest that porcine FTH and EPOR genes may contribute to the reproductive processes of pigs with regards to litter size and confirm the importance of these genes as candidate genes for improving litter size in pigs.