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Cell migration is essential for regulating many biological processes in physiological or pathological conditions, including embryonic development and cancer invasion. In vitro and in silico studies suggest that collective cell migration is associated with some biomechanical particularities, such as restructuring of extracellular matrix (ECM), stress and force distribution profiles, and reorganization of cytoskeleton. Therefore, the phenomenon could be understood by an in-depth study of cells' behavior determinants, including but not limited to mechanical cues from the environment and from fellow "travelers". This review article aims to cover the recent development of experimental and computational methods for studying the biomechanics of collective cell migration during cancer progression and invasion. We also summarized the tested hypotheses regarding the mechanism underlying collective cell migration enabled by these methods. Together, the paper enables a broad overview on the methods and tools currently available to unravel the biophysical mechanisms pertinent to cell collective migration, as well as providing perspectives on future development towards eventually deciphering the key mechanisms behind the most lethal feature of cancer. I.

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There is a close correlation between body health and the level of biofluid-derived metal ions, which makes it an attractive model analyte for noninvasive health monitoring. The present work has developed a novel nose/tongue-mimic chemosensor array based on bioinspired polydopamine/polyethylenimine copolymers (PDA/PEI ) for label-free fluorescent determination of metal ions in biofluids. Three types of PDA/PEI (PDA/PEI, PDA/PEI, and PDA/PEI) were prepared by using different concentrations of PEI to construct the proposed sensor array, which would lead to unique fluorescence response patterns upon challenged with metal ions for their pattern discrimination. The results show that as few as 3 PDA/PEI sensors can successfully realize the largescale sensitive detection of metal ions in biofluids. Moreover, we have demonstrated that PDA/PEI sensors are qualified for lifetime-based pattern discrimination application. Furthermore, the sensors can distinguish between different concentrations of metal ions, as well as a mixture of different metal ions in biofluids, even the mixtures with different valence states. The method promises the simple, rapid, sensitive, and powerful discrimination of metal ions in accessible biofluids, showing the potential applications in the diagnosis of metal ion-involved diseases.

Fusarium graminearum contains eight chitin synthase (Chs) genes belonging to seven classes. Previous studies have found that deletion of FgChs3b is lethal to F. graminearum, and deletion of FgChs1, FgChs2, FgChs7 and FgChs5 caused diverse defects in chitin content, mycelial growth, conidiation, virulence or stress responses. However, little is known about the functional relationships among these FgChss. In this study, FgChs2 deletion mutant ΔFgChs2 exhibited reduced mycelial growth and virulence as reported previously. In addition, we found that the mutant produced thickened and “wavy” septa. Quantitative real-time PCR (qRT-PCR) assays showed that the expression levels of FgChs1, FgChs3a, FgChs4, FgChs7, FgChs5 and FgChs6 in ΔFgChs2 were significantly higher than those in the wild type. Therefore, we generated six double deletion mutants of FgChs2 and each of the above six FgChss, and found that FgChs2 shares a function with FgChs1 in regulating mycelial growth, and co-regulates conidiation with FgChs1, FgChs4, FgChs7 and FgChs5. Furthermore, FgChs2 and other six FgChss have overlapped functions in virulence, DON production and septum formation. Taken together, these results indicate that although each chitin synthase of F. graminearum plays certain roles, FgChss may co-regualte various cellular processes in F. graminearum.

Recent years have witnessed the rapid development of pattern-based sensors due to their potential to detect and differentiate a wealth of analytes with only few probes. However, no one has found or used the combination of DNA and terbium(III) (Tb) as a pattern recognition system for large-scale mix-and-measure assays. Here we report for the first time that DNA-sensitized Tb (DNA/Tb), as a label-free and versatile "chemical nose/tongue", can be employed for wide-scale time-gated luminescent (TGL) monitoring of metal ions covering nearly the entire periodic table in a cost-effective fashion. A series of guanine/thymine (G/T)-rich DNA ligands was screened to sensitize the luminescence of Tb (referring to the antenna effect) as smart pattern responders to metal ions in solution, and metal ion-DNA interactions can differentially alter the antenna effect of DNA toward Tb as pattern signals. Our results show that as few as 3 DNA/Tb label-free sensors could successfully discriminate 49 analytes, including alkali-metal ions, alkaline-earth-metal ions, transition/post-transition metal ions, and lanthanide ions. A blind test with 49 metals further confirmed the discriminating power of DNA/Tb sensors. Moreover, the lifetime-based pattern recognition application using DNA/Tb sensors was also demonstrated. This DNA/Tb pattern recognition strategy could be extended to construct a series of "chemical noses/tongues" for monitoring various biochemical species by using different responsive DNA ligands, thus promising a versatile and powerful tool for a sensing application and investigation of DNA-involving molecular interactions.