Single-cell RNA Sequencing Revealed the Liver Heterogeneity Between Egg-Laying Duck and Ceased-Laying Duck

Background In the late phase of production, ducks untimely cease laying, leading to a lower feed conversion. Liver plays a vital role in the synthesis and transport of yolk materials during egg formation in birds. However, the molecular mechanism of liver in ceased-laying duck is far from clear, higher resolution and deeper analysis is needed. Sing-cell RNA-sequencing of 10 × Genomics platform can help to map the liver single cell gene expression atlas of Shaoxing duck and provide new insights into the liver between egg-laying and ceased-laying ducks. Results About 20,000 single cells were profiled and 22 clusters were identified. All the clusters were identified as 6 cell types. The dominant cell type is hepatocyte, accounted for about 60% of all the cells. Of note, the heterogeneity of cells between egg-laying duck and ceased-laying duck mainly occurred in hepatocytes. Cells of cluster 3 and 12 were the unique hepatocyte states of egg-laying ducks, while cells of cluster 0 and 15 were the unique hepatocyte states of ceased-laying ducks. The expression mode of yolk precursor transporters, lipid metabolizing enzymes and fibrinogens were different in hepatocytes between egg-laying duck and ceased-laying duck. APOV1 , VTG2 , VTG1 , APOB , RBP , VTDB and SCD might be activated in egg-laying ducks, while APOA1 , APOA4 , APOC3 , FGB and FGG might be activated in ceased-laying ducks. Conclusions Our study further proofs that APOV1 and APOB play key roles in egg production, rather than APOA1 and APOA4 . It is also the first to detect a correlation between the higher expression of APOC3 , FGB , FGG and ceased-laying in duck.