This genome-wide association study (GWAS) was conducted to identify major loci that are significantly associated with carcass weight, and their effects, in order to provide increased understanding of the genetic architecture of carcass weight in Hanwoo. This genome-wide association study identified one major chromosome region ranging from 23 Mb to 25 Mb on chromosome 14 as being associated with carcass weight in Hanwoo. Significant Bonferroni-corrected genome-wide associations (P<1.52×10−6) were detected for 6 Single Nucleotide Polymorphic (SNP) loci for carcass weight on chromosome 14. The most significant SNP was BTB-01280026 (P = 4.02×10−11), located in the 25 Mb region on Bos taurus autosome 14 (BTA14). The other 5 significant SNPs were Hapmap27934-BTC-065223 (P = 4.04×10−11) in 25.2 Mb, BTB-01143580 (P = 6.35×10−11) in 24.3 Mb, Hapmap30932-BTC-011225 (P = 5.92×10−10) in 24.8 Mb, Hapmap27112-BTC-063342 (P = 5.18×10−9) in 25.4 Mb, and Hapmap24414-BTC-073009 (P = 7.38×10−8) in 25.4 Mb, all on BTA 14. One SNP (BTB-01143580; P = 6.35×10−11) lies independently from the other 5 SNPs. The 5 SNPs that lie together showed a large Linkage disequilibrium (LD) block (block size of 553 kb) with LD coefficients ranging from 0.53 to 0.89 within the block. The most significant SNPs accounted for 6.73% to 10.55% of additive genetic variance, which is quite a large proportion of the total additive genetic variance. The most significant SNP (BTB-01280026; P = 4.02×10−11) had 16.96 kg of allele substitution effect, and the second most significant SNP (Hapmap27934-BTC-065223; P = 4.04×10−11) had 18.06 kg of effect on carcass weight, which correspond to 44% and 47%, respectively, of the phenotypic standard deviation for carcass weight in Hanwoo cattle. Our results demonstrated that carcass weight was affected by a major Quantitative Trait Locus (QTL) with a large effect and by many SNPs with small effects that are normally distributed.

To understand molecular genetic characteristics of Korean pigs, the genetic relationships of nine pig breeds including two Korean pigs (Korean native pig and Korean wild pig), three Chinese pigs (Min pig, Xiang pig, and Wuzhishan pig), and four European breeds (Berkshire, Duroc, Landrace, and Yorkshire) were characterized from a 16-microsatellite loci analysis. The mean heterozygosity within breeds ranged from 0.494 to 0.703. Across multiple loci, significant deviation from Hardy-Weinberg equilibrium was observed in most pig breeds, except for two Chinese pigs (Min pig and Wuzhishan pig). This deviation was in the direction of heterozygote deficit. Across population loci, 36 of 144 significantly deviated (P < 0.05) from Hardy-Weinberg equilibrium. The mean FST, a measure of genetic divergence among subpopulations, of all loci indicated that 26.1% of total variation could be attributed to the breed difference. Relationship trees based on the Nei's DA genetic distance and scatter diagram from principal component analysis consistently displayed pronounced genetic differentiation among the Korean wild pig, Xiang pig, and Wuzhishan pig. Individual assignment test using a Bayesian method showed 100% success in assigning Korean and Chinese individual pigs into their correct breeds of origin and 100% exclusion success from all alternative reference populations at P < 0.001. These findings indicate that the Korean native pig has been experiencing progressive interbreeding with Western pig breeds after originating from a North China pig breed with a black coat color. Considering the close genetic relationship of Korean pigs to the Western breeds such as Berkshire and Landrace, our findings can be used as valuable genetic information for the preservation and further genetic improvement of the Korean native pig.

Obesity represents a major global public health problem that increases the risk for cardiovascular or metabolic disease. The pigs represent an exceptional biomedical model related to energy metabolism and obesity in humans. To pinpoint causal genetic factors for a common form of obesity, we conducted local genomic de novo sequencing, 18.2 Mb, of a porcine QTL region affecting fatness traits, and carried out SNP association studies for backfat thickness and intramuscular fat content in pigs. In order to relate the association studies in pigs to human obesity, we performed a targeted genome wide association study for subcutaneous fat thickness in a cohort population of 8,842 Korean individuals. These combined association studies in human and pig revealed a significant SNP located in a gene family with sequence similarity 73, member A (FAM73A) associated with subscapular skin-fold thickness in humans (rs4121165, GC-corrected p-value  = 0.0000175) and with backfat thickness in pigs (ASGA0029495, p-value  = 0.000031). Our combined association studies also suggest that eight neuronal genes are responsible for subcutaneous fat thickness: NEGR1, SLC44A5, PDE4B, LPHN2, ELTD1, ST6GALNAC3, ST6GALNAC5, and TTLL7. These results provide strong support for a major involvement of the CNS in the genetic predisposition to a common form of obesity.

Intramuscular fat (IMF) content in pork is an important element of consumer preference and is positively correlated with meat quality, including tenderness and juiciness. With advances in RNA sequencing technologies, transcriptome-related differences can be associated with specific traits in animals. The objective of this study was to investigate differentially expressed genes (DEGs) closely related to IMF content in porcine longissimus muscle using RNA sequencing. A total of 107 Berkshire pigs were used for IMF content measurements, and significant differences between extremely high (H, n = 3) and low (L, n = 3) IMF content groups were found (P < 0.0001). From multi-dimensional scaling analyses, it was observed that the relationships between H and L groups were similar to each other. Here, we identified a total of 134 genes that were differentially expressed between the groups (false discovery rate <0.05; fold change ≥2). Functional analyses with DEGs revealed that lipid metabolism (SCD and FASN) was one of the significant biological processes related to IMF content determination. In addition, we found that DEGs related to muscle regeneration (MYOG and VEGFA) and extracellular matrix (COL1A1, COL1A2, COL5A1, COL14A1 and COL15A1) were changed among individuals with extreme IMF contents. These results will aid in understanding the regulation of IMF content in pigs.