Colony spreading of Flavobacterium johnsoniae is shown to include gliding motility using the cell surface adhesin SprB, and is drastically affected by agar and glucose concentrations. Wild-type (WT) and ΔsprB mutant cells formed nonspreading colonies on soft agar, but spreading dendritic colonies on soft agar containing glucose. In the presence of glucose, an initial cell growth-dependent phase was followed by a secondary SprB-independent, gliding motility-dependent phase. The branching pattern of a ΔsprB colony was less complex than the pattern formed by the WT. Mesoscopic and microstructural information was obtained by atmospheric scanning electron microscopy (ASEM) and transmission EM, respectively. In the growth-dependent phase of WT colonies, dendritic tips spread rapidly by the movement of individual cells. In the following SprB-independent phase, leading tips were extended outwards by the movement of dynamic windmill-like rolling centers, and the lipoproteins were expressed more abundantly. Dark spots in WT cells during the growth-dependent spreading phase were not observed in the SprB-independent phase. Various mutations showed that the lipoproteins and the motility machinery were necessary for SprB-independent spreading. Overall, SprB-independent colony spreading is influenced by the lipoproteins, some of which are involved in the gliding machinery, and medium conditions, which together determine the nutrient-seeking behavior.

Multi-thermoresponsiveness which exhibits more than triple phase transitions has not been achieved yet. Current research studies have reported double thermoresponsive copolymers having two kinds of polymer chains. However, the molecular design strategy of triple thermoresponsiveness remains unclear. Herein, we report a triple thermoresponsive chiral homopolymer which exhibits UCST− LCST−UCST-type phase transitions. The polymer contains the α,α,α′,α′-tetraaryl-2,2-disubstituted 1,3-dioxolane-4,5-dimethanol moiety in the side chains, where multiple supramolecular complexes between the host polymer and guest molecules are formed. The formations and dynamic changes in the multiple complexes of model compounds were monitored by 1 H NMR spectroscopy. We concluded that the key factor of the triple thermoresponsive behavior is the stoichiometric change in the multiple complexes. This work can extend the molecular design of the thermoresponsive polymer and lead to the next stage of functional polymer materials.

Thermoresponsive polymers in water, for example, poly(N‐isopropylacrylamide) (PNIPAM) are investigated extensively, due to a wide range of biomedical applications. However, the attempts to control thermoresponsiveness are still rare in less or nonpolar media. Herein, the three thermoresponsive homopolymers tethering an N‐butylurea group in the side chain with a different polymer backbone are reported. They exhibit lower critical solution temperature (LCST)‐type and upper critical solution temperature (UCST)‐type thermoresponsiveness depending on association of the urea group in the polymer chain and hydrogen bonding small molecules (effectors) in ternary systems (polymer/effector/organic solvent). The difference of polymer backbone appears as their change of solvophobicity in organic solvents. Poly(methacrylate) backbone needs more amount of the effector in nonpolar organic solvents, and poly(vinyl ether) backbone needs more amount in polar organic solvents. However, the influence of polymer backbone is too little to change the phase transition behavior, and the thermoresponsiveness is dominated by association and dissociation of hydrogen bondings between polymers and effectors. The supramolecular design of the thermoresponsive polymers is strong and extensible for the design of their phase transitions.

A novel gel LCST system was constructed by utilizing the CT interaction between the gel and external effector, thus shrinking upon heating with hypochromic colour change.

Fluorescence microscopy (FM) has revealed vital molecular mechanisms of life. Mainly, molecules labeled by fluorescent probes are imaged. However, the diversity of labeling probes and their functions remain limited. We synthesized a pyrene-based fluorescent probe targeting SH groups, which are important for protein folding and oxidative stress sensing in cells. The labeling achieved employs thiol-ene click reactions between the probes and SH groups and is triggered by irradiation by UV light or an electron beam. When two tagged pyrene groups were close enough to be excited as a dimer (excimer), they showed red-shifted fluorescence; theoretically, the proximity of two SH residues within ~30 Å can thus be monitored. Moreover, correlative light/electron microscopy (CLEM) was achieved using our atmospheric scanning electron microscope (ASEM); radicals formed in liquid by the electron beam caused the thiol-ene click reactions, and excimer fluorescence of the labeled proteins in cells and tissues was visualized by FM. Since the fluorescent labeling is induced by a narrow electron beam, high spatial resolution labeling is expected. The method can be widely applied to biological fields, for example, to study protein dynamics with or without cysteine mutagenesis, and to beam-induced micro-fabrication and the precise post-modification of materials.