Haematological traits play important roles in disease resistance and defence functions. The objective of this study was to locate quantitative trait loci (QTL) and the associated positional candidate genes influencing haematological traits in an F(2) intercross between Landrace and Korean native pigs. Eight blood-related traits (six erythrocyte traits, one leucocyte trait and one platelet trait) were measured in 816 F(2) progeny. All experimental animals were genotyped with 173 informative microsatellite markers located throughout the pig genome. We report that nine chromosomes harboured QTL for the baseline blood parameters: genomic regions on SSC 1, 4, 5, 6, 8, 9, 11, 13 and 17. Eight of twenty identified QTL reached genome-wide significance. In addition, we evaluated the KIT locus, an obvious candidate gene locus affecting variation in blood-related traits. Using dense single nucleotide polymorphism marker data on SSC 8 and the marker-assisted association test, the strong association of the KIT locus with blood phenotypes was confirmed. In conclusion, our study identified both previously reported and novel QTL affecting baseline haematological parameters in pigs. Additionally, the positional candidate genes identified here could play an important role in elucidating the genetic architecture of haematological phenotype variation in swine and in humans.

Metabolic organs such as the liver and adipose tissue produce several peptide hormones that influence metabolic homeostasis. Fat bodies, the Drosophila counterpart of liver and adipose tissues, have been thought to analogously secrete several hormones that affect organismal physiology, but their identity and regulation remain poorly understood. Previous studies have indicated that microRNA miR-8, functions in the fat body to non-autonomously regulate organismal growth, suggesting that fat body-derived humoral factors are regulated by miR-8. Here, we found that several putative peptide hormones known to have mitogenic effects are regulated by miR-8 in the fat body. Most members of the imaginal disc growth factors and two members of the adenosine deaminase-related growth factors are up-regulated in the absence of miR-8. Drosophila insulin-like peptide 6 (Dilp6) and imaginal morphogenesis protein-late 2 (Imp-L2), a binding partner of Dilp, are also up-regulated in the fat body of miR-8 null mutant larvae. The fat body-specific reintroduction of miR-8 into the miR-8 null mutants revealed six peptides that showed fat-body organ-autonomous regulation by miR-8. Amongst them, only Imp-L2 was found to be regulated by U-shaped, the miR-8 target for body growth. However, a rescue experiment by knockdown of Imp-L2 indicated that Imp-L2 alone does not account for miR-8's control over the insect's growth. Our findings suggest that multiple peptide hormones regulated by miR-8 in the fat body may collectively contribute to Drosophila growth.

Genome-wide association studies (GWASs) have identified common single nucleotide polymorphisms (SNPs) in more than 100 genomic regions associated with atrial fibrillation (AF). Genes for AF identified by GWAS in the Caucasian populations may show ethnic differences in the Asian populations. We sought to identify other novel AF genes in the Taiwanese population by multi-stage GWAS. Methods In exploratory stage, GWAS with whole genome genotypes (4,512,191 SNPs) were done in 516 young AF Patients (58.1±8.7 years-old, 438 men [84.9%]) from the National Taiwan University AF registry (NTUAFR) and 5160 normal sinus rhythm controls (57.8 ±8.7 years-old, 2460 men [47.7%]) from Taiwan Biobank. Significant loci were replicated in 1002 independent AF patients and 2003 NSR controls, and also in UK biobank (5630 AF cases and 24000 NSR controls). Quantitative trait locus mapping was performed to implicate functional significance. Results Stage I GWAS revealed 3 loci associated with AF with the genome-wide significance level, which included locus close to previously reported PITX2 gene (chromosome 4q25, rs2723329, P=1.53×10-10) and two novel loci close to RAP1A and HNF4G genes (chromosome 1p13.2, rs7525578, P=1.24× 10-26; chromosome 8q21.13, rs2980218, P=2.19×10-9, respectively). They were further validated in a stage II replication population (P=4.60×10-9, 4.45×10-10 and 6.97×10-5 for RAP1A, PITX2 and HNF4G, respectively). These 3 genes were also validated in the UK population. These 3 significant SNPs also show significant association with tissue expressions (RAP1A expression in thyroid, PITX2 in testicular, and HNF4G in lymphocyte tissues, respectively). Conclusions GWAS in Taiwan revealed previously reported PITX2 and two novel AF genes (RAP1A and HNF4G) with the most significant locus in RAP1A. RAP1A and HNF4G genes may implicate fibrosis and metabolic pathways, respectively, in the mechanism of AF.