Embryonic liver developmental trajectory revealed by single-cell RNA sequencing in the Foxa2eGFP mouse.

The liver and gallbladder are among the most important internal organs derived from the endoderm, yet the development of the liver and gallbladder in the early embryonic stages is not fully understood. Using a transgenic Foxa2eGFP reporter mouse line, we performed single-cell full-length mRNA sequencing on endodermal and hepatic cells isolated from ten embryonic stages, ranging from E7.5 to E15.5. We identified the embryonic liver developmental trajectory from gut endoderm to hepatoblasts and characterized the transcriptome of the hepatic lineage. More importantly, we identified liver primordium as the nascent hepatic progenitors with both gut and liver features and documented dynamic gene expression during the epithelial-hepatic transition (EHT) at the stage of liver specification during E9.5-11.5. We found six groups of genes switched on or off in the EHT process, including diverse transcripitional regulators that had not been previously known to be expressed during EHT. Moreover, we identified and revealed transcriptional profiling of gallbladder primordium at E9.5. The present data provides a high-resolution resource and critical insights for understanding the liver and gallbladder development.

Comparative analysis of sequencing technologies for single-cell transcriptomics.

Single-cell RNA-seq technologies require library preparation prior to sequencing. Here, we present the first report to compare the cheaper BGISEQ-500 platform to the Illumina HiSeq platform for scRNA-seq. We generate a resource of 468 single cells and 1297 matched single cDNA samples, performing SMARTer and Smart-seq2 protocols on two cell lines with RNA spike-ins. We sequence these libraries on both platforms using single- and paired-end reads. The platforms have comparable sensitivity and accuracy in terms of quantification of gene expression, and low technical variability. Our study provides a standardized scRNA-seq resource to benchmark new scRNA-seq library preparation protocols and sequencing platforms.

Multi-scale pectin/polyphenol beads for non-fouling fluorescence tracking on soft matter under water.

The smart polyphenol material could be designed to form two competitive interactions related to same one polyphenol molecule with different objects that could easily adhere to one surface through the weak interaction, and also could be entirely removed from the same surface by the strong interaction. In this study, the multi-scale pectin beads were fabricated by crosslinking with ions that could be acted as polyphenol loading agent through electrostatic force between the ions loading on the surface of pectin beads and polyphenol. The two effects on the size and appearance of pectin beads were detected. Because of the hydrogen bond between polyphenols loading on the beads and the surface of target, fluorescence-functionalized beads could easily adhere on target surfaces. Meanwhile, attributing to stronger electrostatic force between surface ions on beads and polyphenol, the thin membrane made of the beads can be entirely removed from the target surface to avoid the pollution of fluorescence probes.