3D imaging of single bacterial cells using surface-enhanced Raman spectroscopy with a multivariate curve resolution model.

Imaging biomolecules within a single bacterial cell is crucial for understanding cellular genetic mechanisms. Herein, we exploited a surface-enhanced Raman spectroscopy (SERS) imaging strategy for single cell analysis. Cellular biosynthesized Ag nanoparticles (NPs) provided the necessary enhancement for SERS imaging. Multiple complementary techniques, including high-resolution transmission electron microscopy (HR-TEM), high-angle annular dark-field (HAADF)-scanning transmission electron microscopy (STEM), and energy-dispersive X-ray spectroscopy (EDX), were used to characterize the biogenic Ag NPs in cells. Three-dimensional SERS imaging maps displayed spectral information of biomolecules within the single cell. The multivariate curve resolution (MCR) model and principal component analysis (PCA) model were used to analyze the cellular SERS imaging maps. The MCR model, with a specific constraint of non-negativity, resulted in meaningful identification of biomolecules associated with Ag reduction. Focusing on the molecular level reveals that Pantoea sp. IMH utilizes several mechanisms to synthesize Ag NPs, including cytoplasm reduction by glucose or nicotinamide adenine dinucleotide (NADH)-dependent reductase, and extracellular reduction by an electron transfer chain containing quinone and cytochrome C. Our results shed new light on the Ag NP biosynthesis mechanism and single cell Raman analysis.

Sampsonione F suppresses adipogenesis via activating p53 pathway during the mitotic clonal expansion progression of adipocyte differentiation.

The abnormal proliferation and hypertrophy of adipocytes mediate the expansion of adipose tissue and then cause obesity-related diseases. Theoretically, an approach for preventing and curing obesity is to inhibit cell proliferation during the mitotic clonal expansion (MCE) progression of adipocyte differentiation. Polycyclic polyprenylated acylphloroglucinols (PPAPs) are mainly found from Hypericum and Garcinia genus, which have been reported to have various biological activities such as anti-depressant, anti-oxidant, and anti-tumor. Previously, our group has reported that adamantane-type PPAPs exhibited blunting activity in adipogenesis. In this study, another six adamantane PPAPs were screened to investigate their anti-adipogenesis activities and then discussed the structure-activity relationship. Particularly, sampsonione F, one of the PPAPs dramatically suppressed adipogenesis dose-dependently in vitro, along with decreased expressions of C/EBPß, C/EBPα, PPARγ, FABP4, and FAS. Moreover, sampsonione F upregulated the expression of p27 by activating p53 pathway and then downregulated the expressions of key regulators during G1/S phase arrest. Our data support that sampsonione F suppressed adipogenesis by activating p53 pathway, regulating cyclins, and resulting in G1/S phase arrest during the MCE progression of adipogenesis. This work provides a new adamantane-type PPAPs in the regulation of adipogenesis and extends our knowledges on the mechanism of the type PPAPs in regulation of adipogenesis.