Responsive Microgels through RAFT-HDA Dynamic Covalent Bonding Chemistry.

This paper developed a method for preparing ultrasound-responsive microgels based on reversible addition fragmentation chain transfer-hetero Diels-Alder (RAFT-HAD) dynamic covalent bonding. First, a styrene cross-linked network was successfully prepared by a Diels-Alder (DA) reaction between phosphoryl dithioester and furan using double-ended diethoxyphosphoryl dithiocarbonate (BDEPDF) for RAFT reagent-mediated styrene (St) polymerization, with a double-ended dienophile linker and copolymer of furfuryl methacrylate (FMA) and St as the dienophile. Subsequently, the microgel system was constructed by the HDA reaction between phosphoryl disulfide and furan groups using the copolymer of polyethylene glycol monomethyl ether acrylate (OEGMA) and FMA as the dienophore building block and hydrophilic segment and the polystyrene pro-dienophile linker as the cross-linker and hydrophobic segment. The number of furans in the dienophile chain and the length of the dienophile linker were regulated by RAFT polymerization to investigate the effects of the single-molecule chain functional group degree, furan/dithioester ratio, and hydrophobic cross-linker length on the microgel system. The prepared microgels can achieve the reversible transformation of materials under force responsiveness, and their preparation steps are simple and adaptive to various potential applications in biomedical materials and adaptive electrical materials.

Cross-Tissue Characterization of Heterogeneities of Mesenchymal Stem Cells and Their Differentiation Potentials.

Mesenchymal stem/stromal cells (MSCs) are promising cell sources for regenerative medicine and the treatment of autoimmune disorders. Comparing MSCs from different tissues at the single-cell level is fundamental for optimizing clinical applications. Here we analyzed single-cell RNA-seq data of MSCs from four tissues, namely umbilical cord, bone marrow, synovial tissue, and adipose tissue. We identified three major cell subpopulations, namely osteo-MSCs, chondro-MSCs, and adipo/myo-MSCs, across all MSC samples. MSCs from the umbilical cord exhibited the highest immunosuppression, potentially indicating it is the best immune modulator for autoimmune diseases. MSC subpopulations, with different subtypes and tissue sources, showed pronounced differences in differentiation potentials. After we compared the cell subpopulations and cell status pre-and-post chondrogenesis induction, osteogenesis induction, and adipogenesis induction, respectively, we found MSC subpopulations expanded and differentiated when their subtypes consist with induction directions, while the other subpopulations shrank. We identified the genes and transcription factors underlying each induction at the single-cell level and subpopulation level, providing better targets for improving induction efficiency.

Determining factors, regulation system, and domestication of anthocyanin biosynthesis in rice leaves.

Wild and cultivated rice show a significant difference in anthocyanin biosynthesis in the leaf. The regulation system of anthocyanin biosynthesis in rice leaf and the causal mechanism of the difference in this biosynthesis between wild and cultivated rice remain largely unknown. In this study, a genome-wide association study and transcriptome analysis were performed to identify the determinant factors and dissect the regulatory system for anthocyanin biosynthesis in rice leaves. OsC1, OsRb and OsDFR were identified as the determinants of anthocyanin biosynthesis in rice leaves. Artificial selection of certain null mutations of OsC1 and OsRb was the main causal mechanism underlying the loss of anthocyanin pigmentation in most cultivated rice. OsP1 and the MYB-bHLH-WD40 complexes regulate anthocyanin biosynthetic genes in rice leaves with partial functional overlap. OsP1 specifically activates upstream biosynthetic genes (OsCHS, OsCHI and OsF3'H) for anthocyanin biosynthesis, whereas the ternary MYB-bHLH-WD40 complex activates all anthocyanin biosynthetic genes including OsCHS, OsCHI, OsF3'H, OsF3H, OsDFR and OsANS. OsC1 and OsRb are tissue-specific regulators that do not influence anthocyanin biosynthesis in the pericarp. Our results reveal the determinant factors, regulatory system and domestication of anthocyanin biosynthesis in rice leaves, and show the potential of engineering anthocyanin biosynthesis in rice.