Genome‐wide association studies reveal genetic loci associated with plasma cholinesterase activity in ducks

A novel candidate gene CLN8 regulates fat deposition in avian

BACKGROUND

The fat deposition has a crucial role in animal meat flavor, and fat deposition-related traits are vital for breeding in the commercial duck industry. Avian fat-related traits are typical complex phenotypes, which need a large amount of data to analyze the genetic loci.

RESULTS

In this study, we performed a new phenotypic analysis of fat traits and genotyped whole-genome variations for 1,246 ducks, and combed with previous GWAS data to reach 1,880 ducks for following analysis. The carcass composition traits, subcutaneous fat weight (SFW), subcutaneous fat percentage (SFP), abdominal fat weight (AFW), abdominal fat percentage (AFP) and the body weight of day 42 (BW42) for each duck were collected. We identified a set of new loci that affect the traits related to fat deposition in avian. Among these loci, ceroid-lipofuscinosis, neuronal 8 (CLN8) is a novel candidate gene controlling fat deposition. We investigated its novel function and regulation in avian adipogenesis. Five significant SNPs (the most significant SNP, P-value = 21.37E-12) and a single haplotype were detected in the upstream of CLN8 for subcutaneous fat percentage. Subsequently, luciferase assay demonstrated that 5 linked SNPs in the upstream of the CLN8 gene significantly decreased the transcriptional activity of CLN8. Further, ATAC-seq analysis showed that transcription factor binding sites were identified in a region close to the haplotype. A set of luciferase reporter gene vectors that contained different deletion fragments of the CLN8 promoter were constructed, and the core promoter area of CLN8 was finally identified in the -1,884/-1,207 bp region of the 5' flanking sequences, which contains adipogenesis-related transcription factors binding sites. Moreover, the over-expression of CLN8 can remarkably facilitate adipocyte differentiation in ICPs. Consistent with these, the global transcriptome profiling and functional analysis of the over-expressed CLN8 in the cell line further revealed that the lipid biosynthetic process during the adipogenesis was significantly enriched.

CONCLUSIONS

Our results demonstrated that CLN8 is a positive regulator of avian adipocyte differentiation. These findings identify a novel function of CLN8 in adipocyte differentiation, which provides important clues for the further study of the mechanism of avian fat deposition.

Genome-wide association study reveals novel loci associated with fat-deposition and meat-quality traits in Pekin ducks

Meat-quality traits play an essential role in meat poultry production. To determine the genetic mechanisms of meat quality in Pekin ducks, we performed a large-scale GWAS to identify quantitative trait loci affecting meat quality in Pekin ducks. We measured 10 traits in 542 Pekin ducks and genotyped each duck using genotyping-by-sequencing. The genetic parameters (genomic heritability, genetic correlation) for 10 meat-quality related traits were evaluated. Based on the large genotype-phenotype dataset, we performed GWASs for all of these traits. A total of 33 significant QTL (P < 3.03 × 10^-5 ) across 13 chromosomes were identified by loci-based analysis. Some newly identified candidate genes were discovered for fat-deposition and meat-quality traits, including PAG1 for body weight and eviscerated weight, INTU and NUP35 for abdominal fat weight and ratio, NUP3 and ARHGDIB for skin fat weight and ratio, GOLGA5 for breast muscle toughness and breast tenderness, and CTDSPL and PKP1 for breast muscle thickness. The current study is the first systematic report regarding duck meat quality.