生物物理学报:英文版最新文献

Bioluminescence technology has been widely used in the field of medical detection. The bioluminescent lux reporter system provides a non-invasive platform to monitor bacterial growth and expression in real time. This study aimed to establish a method for detecting bacterial adhesion on the surface of materials, including medical devices, by using recombinant bioluminescent Pseudomonas aeruginosa containing a lux reporter. By monitoring the growth and bioluminescent properties of the recombinant PAO1-lux strain, the optimal test conditions for bacterial adhesion detection in vitro were determined to be as follows: an initial inoculation density of 10⁵ to 10⁶ CFU/mL, M9 medium at a pH 6.2, an adhesion time of 6 h, and the collection of adherent bacteria by ultrasonic cleaning. The traditional CFU counting method and the bioluminescence method were compared, and the applicability of the new method was verified by testing the adhesion of bacteria on the surface of various materials. The validated bioluminescent strains could serve as strong candidates to be used as bacterial detection tools in applications such as bacterial adhesion evaluation as well as supplements and alternatives to traditional microbiological testing procedures. In addition, this method has the potential to enable the study of bacterial adhesion on the surface of inanimate objects and living tissues. With the development of this method and its wide applicability, it is expected to become a standard method for the detection of bacterial adhesion and the screening of anti-adhesion materials.

Hippo pathway can regulate cell division, differentiation and apoptosis, and control the shape and size of organs. To study the distribution patterns of histone modifications of Hippo pathway genes in embryonic stem cells is helpful to understand the molecular regulation mechanism of histone modification and Hippo pathway on stem cell self-renewal. In this study, 19 genes of Hippo pathway including YAP, TAZ, LATS1/2, MST1 and SAV1, and eight histone modifications in embryonic stem cells were chosen to study the spatial distribution patterns of histone modifications. It was found that there were obvious type specificity and the location preference of target regions in the distributions of histone modifications, and H3K4me3 and H3K36me3 played the most important regulatory roles. Through the correlation analysis of histone modifications, a histone modification functional cluster composed of H3K4ac, H3K4me3, H3K9ac and H3K27ac was detected in YAP. In addition, the spatial distribution patterns of histone modifications in Hippo pathway genes were obtained, which provided a new theoretical reference for elucidating the mechanism of histone modifications regulating the gene expression of Hippo pathway, and for revealing the molecular regulatory mechanism of histone modifications affecting the self-renewal of embryonic stem cells by regulating the Hippo pathway.

Structurally reconfigurable RNA structures enable dynamic transitions of the functional states in response to diverse molecular stimuli, which are fundamental in genetic and epigenetic regulations. Inspired by nature, rationally designed RNA structures with responsively reconfigurable motifs have been developed to serve as switchable components for building engineered nanomachines, which hold promise in synthetic biological applications. In this review, we summarize recent progress in the design, synthesis, and integration of engineered reconfigurable RNA structures for nanomachines. We highlight recent examples of their targeted applications such as biocomputing and smart theranostics. We also discuss their advantages, challenges as well as possible solutions. We further provide an outlook of their potential in future synthetic biology.

Lysosomes are membrane-bound organelles for biomolecule degradation and recycling. They also serve as a nutrient sensing and signaling center to maintain cell and tissue homeostasis. Lysosomal properties alter in response to developmental or environmental cues, but these changes are hard to track in vivo. Employing C. elegans as a model system, we have developed assays to examine and quantify lysosome properties in vivo, including lysosome maturation, acidification and cleavage activity. These assays can be used to reveal alterations of lysosomal activity during C. elegans development and in stress conditions.

Tumour vasculature is known to be aberrant, tortuous and erratic which can have significant implications for fluid flow. Fluid dynamics in tumour tissue plays an important part in tumour growth, metastasis and the delivery of therapeutics. Mathematical models are increasingly employed to elucidate the complex interplay between various aspects of the tumour vasculature and fluid flow. Previous models usually assume a uniformly distributed vasculature without explicitly describing its architecture or incorporate the distribution of vasculature without accounting for real geometric features of the network. In this study, an integrated computational model is developed by resolving fluid flow at the single capillary level across the whole tumour vascular network. It consists of an angiogenesis model and a fluid flow model which resolves flow as a function of the explicit vasculature by coupling intravascular flow and interstitial flow in tumour tissue. The integrated model has been used to examine the influence of microvascular distribution, necrosis and vessel pruning on fluid flow, as well as the effect of heterogeneous vessel permeability. Our results reveal the level of nonuniformity in tumour interstitial fluid pressure (IFP), with large variations in IFP profile between necrotic and non-necrotic tumours. Changes in microscopic features of the vascular network can significantly influence fluid flow in the tumour where removal of vessel blind ends has been found to reduce IFP and promote interstitial fluid flow. Our results demonstrate the importance of incorporating microscopic properties of the tumour vasculature and intravascular flow when predicting fluid flow in tumour tissue.

Cancer immunotherapy has made recent breakthrough, including immune checkpoint blockade (ICB) that inhibits immunosuppressive checkpoints such as programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1). However, most cancer patients do not durably respond to ICB. To predict ICB responses for patient stratification, conventional immunostaining has been used to analyze the PD-L1 expression level on biopsied tumor tissues but has limitations of invasiveness and tumor heterogeneity. Recently, PD-L1 levels on tumor cell exosomes showed the potential to predict ICB response. Here, we developed a non-invasive, sensitive, and fast assay, termed as exosome-hybridization chain reaction (ExoHCR), to analyze tumor cell exosomal PD-L1 levels. First, using αCD63-conjugated magnetic beads, we isolated exosomes from B16F10 melanoma and CT26 colorectal cancer cells that were immunostimulated to generate PD-L1-positive exosomes. Exosomes were then incubated with a conjugate of PD-L1 antibody with an HCR trigger DNA (T), in which one αPD-L1-T conjugate carried multiple copies of T. Next, a pair of metastable fluorophore-labeled hairpin DNA (H1 and H2) were added, allowing T on αPD-L1-T to initiate HCR in situ on bead-conjugated exosome surfaces. By flow cytometric analysis of the resulting beads, relative to αPD-L1-fluorophore conjugates, ExoHCR amplified the fluorescence signal intensities for exosome detection by 3-7 times in B16F10 cells and CT26 cells. Moreover, we validated the biostability of ExoHCR in culture medium supplemented with 50% FBS. These results suggest the potential of ExoHCR for non-invasive, sensitive, and fast PD-L1 exosomal profiling in patient stratification of cancer immunotherapy.