Membrane-permeable fluorescent dyes that stain DNA are useful reagents for microscopic imaging, as they can be introduced into living cells to label DNA. However, the number of these dyes, such as Hoechst 33342, is limited. Here, we show that the icosahedral dodecaborate B₁₂Br₁₂^2-, a superchaotropic carrier that delivers different types of molecules into cells, functions as an excellent carrier for membrane-impermeable fluorescent dyes. Propidium iodide (PI) and 4',6-diamidino-2-phenylindole (DAPI), dicationic membrane-impermeable fluorescent dyes that stain DNA, can permeate cell membranes in the presence of boron clusters. Methyl green (MG), a dicationic dye used in the histological and fluorescent staining of DNA, permeated cell membranes in the presence of boron clusters. In contrast, monocationic membrane-permeable fluorescent dyes, such as acridine orange and pyronin Y, exhibited reduced fluorescence in cells in the presence of boron clusters. Boron clusters do not quench dicationic fluorescent dyes in water in vitro but have quenching effects on monocationic fluorescent dyes. We have demonstrated that the addition of B₁₂Br₁₂^2- to impermeable dicationic fluorescent DNA-staining dyes, such as DAPI, PI, and MG, which have been widely used for numerous years, imparts membrane permeability to introduce these dyes into living cells.

The RNA helicase, DDX17 is a member of the DEAD-box protein family. DDX17 has two isoforms: p72 and p82. The p82 isoform has additional amino acid sequences called intrinsically disordered regions (IDRs), which are related to the formation of membraneless organelles (MLOs). Here, we reveal that p72 is mostly localized to the nucleoplasm, while p82 is localized to the nucleoplasm and nucleoli. Additionally, p82 exhibited slower intranuclear mobility than p72. Furthermore, the enzymatic mutants of both p72 and p82 accumulate into the stress granules. The enzymatic mutant of p82 abolishes nucleolar localization of p82. Our findings suggest the importance of IDRs and enzymatic activity of DEAD-box proteins in the intracellular distribution and formation of MLOs.

Protein-bound microparticles formed from anionic boron cluster, cationic polymer and proteins enter the cells via endocytosis. Subsequently, the proteins bound to microparticles are released into the cytosol after endosomal escape.

[B₁₂I₁₂]²⁻ exhibits potent membrane transport yet high cytotoxicity. Stepwise hydroxylation moderates chaotropicity, balancing permeability and biocompatibility. Notably, mono-hydroxylation retains transport activity while minimizing toxicity, whereas further hydroxylation ablates permeability. This strategy advances safe, efficient boron cluster-based carriers for drug delivery and related biomedical applications.

Structures of nucleoprotein (N)–RNA complexes of the Bornaviridae , a virus family in the order Mononegavirales , have not been reported. Here, using cryo–electron microscopy (cryo-EM), we report high-resolution structures of Borna disease virus 1 (BoDV-1) N-RNA complex assemblies, including a dominant hexameric ring-like complex and less populated heptameric and octameric forms, the first RNA-bound N structures reported from this family. These structures reveal key features of N-RNA engagement and a BoDV-1–specific stoichiometry of eight nucleotides per N, providing a framework for comparison with related negative-strand RNA viruses. In addition to these RNA-bound complexes, we identified multiple RNA-free oligomers, indicating substantial conformational flexibility of N. Mutational analyses identified residues essential for nucleocapsid formation and RNA synthesis. Cryo-EM of mutant complexes captured RNA-free assemblies, suggesting that initial N oligomerization precedes RNA binding. These findings clarify the structural organization of the N-RNA complex and suggest how oligomeric plasticity contributes to nucleocapsid assembly.