Detection of four polymorphisms in 5' upstream region of PNPLA2 gene and their associations with economic traits in pigs.

As an important triglyceride hydrolase in mammalian cells, patatin-like phospholipase domain-containing 2 (PNPLA2) predominantly performs the first step in triglyceride hydrolysis. The objective of this study was to detect and evaluate the effects of mutations in the 5' upstream region of porcine PNPLA2 gene with fat deposition and carcass traits. Four single nuclear polymorphisms were identified, including g.161969 T>C, g.161962 A>G, g.161953 C>G and g.161904 G>T, and subsequently genotyped in five pure breeds. Three haplotypes were constructed, including H1(CGGT), H2(TACG) and H3(CACT), which were the most abundant haplotypes in Duroc (0.75), Landrace (0.78) and Chinese indigenous breeds (>0.73), respectively. Duroc individuals with the H1H1 diplotype always exhibited the lowest feed conversion ratio (FCR) (P < 0.05), while H2H2 had the thickest backfat thickness (P < 0.05). Landrace individuals with H2H3 had lower backfat thickness (P < 0.05), higher muscle thickness (P < 0.05) and estimated lean meat percentage (P < 0.05) than those with diplotype H2H2 and H3H3. Luciferase assay indicated pGL3-basic-H2 had the highest activity and pGL3-basic-H1 had the lowest activity in driving reporter gene transcription in HEK293 cells in vitro. In H1 haplotype, two GR binding sites and an ERα binding site were predicted to be introduced. While in H2 and H3, there were other transcriptional factor binding sites predicted in H2 and H3, such as Sp1, AP-2 and CAC-binding proteins, which were broadly expressed transcription factors and capable of contributing to basal promoter activity. The reduced basal promoter activity of H1 may be due to the lack of inducement for GR and ERα binding sites in HEK293 cells. The identified functional polymorphisms provide new evidence of PNPLA2 as an important candidate gene for fat deposition and carcass traits in pigs.

Pangenome obtained by long-read sequencing of 11 genomes reveal hidden functional structural variants in pigs.

Long-read sequencing (LRS) facilitates both the genome assembly and the discovery of structural variants (SVs). Here, we built a graph-based pig pangenome by incorporating 11 LRS genomes with an average of 94.01% BUSCO completeness score, revealing 206-Mb novel sequences. We discovered 183,352 nonredundant SVs (63% novel), representing 12.12% of the reference genome. By genotyping SVs in an additional 196 short-read sequencing samples, we identified thousands of population stratified SVs. Particularly, we detected 7,568 Tibetan specific SVs, some of which demonstrate significant population differentiation between Tibetan and low-altitude pigs, which might be associated with the high-altitude hypoxia adaptation in Tibetan pigs. Further integrating functional genomic data, the most promising candidate genes within the SVs that might contribute to the high-altitude hypoxia adaptation were discovered. Overall, our study generates a benchmark pangenome resource for illustrating the important roles of SVs in adaptive evolution, domestication, and genetic improvement of agronomic traits in pigs.

Screening specifically expressed ESTs related to piglet diarrhea resistance.

RNA was extracted from spleens of diarrhea and non-diarrhea piglets of Jiuyang Pig, Jianbai Pig and Landrace. RNA pools were established and DDRT-PCR using three anchored and seven arbitrary primers combined with silver staining was conducted to identify ESTs differentially expressed in diarrhea resistance to E. coli K88. Five cDNA were identified in the non-diarrhea RNA pools. Among them two are new sequences and three are highly identical to the ESTs in the GeneBank, of which two have known functions. One is the mammalian Nck adaptor protein 1 and the other is the human LINE-1 reverse transcriptase.