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Yuan, R.

Publications and source records attributed to Yuan, R..

42 records · Page 3Linked to original sources

Mapping Vector Field of Single Cells

Single-cell RNA-seq, together with RNA velocity and metabolic labeling, reveals cellular states and transitions at unprecedented resolution. Fully exploiting these data, however, requires dynamical models capable of predicting cell fate and unveiling the governing regulatory mechanisms. Here, we introduce dynamo, an analytical framework that reconciles intrinsic splicing and labeling kinetics to estimate absolute RNA velocities, reconstructs velocity vector fields that predict future cell fates, and finally employs differential geometry analyses to elucidate the underlying regulatory networks. We applied dynamo to a wide range of disparate biological processes including prediction of future states of differentiating hematopoietic stem cell lineages, deconvolution of glucocorticoid responses from orthogonal cell-cycle progression, characterization of regulatory networks driving zebrafish pigmentation, and identification of possible routes of resistance to SARS-CoV-2 infection. Our work thus represents an important step in going from qualitative, metaphorical conceptualizations of differentiation, as exemplified by Waddingtons epigenetic landscape, to quantitative and predictive theories.

systems biology↗

Ibuprofen-mediated potential inhibition of biofilm development and quorum sensing in Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the leading causes of opportunistic and hospital-acquired infections worldwide. The infection with P. aeruginosa is frequently linked with clinical treatment difficulties given drug resistance and abuse of antibiotics. Ibuprofen, a widely used non-steroidal anti-inflammatory drug, has been previously reported to exert antimicrobial activity, although the specific mechanism of its action requires additional investigation. Given the regulation effects on quorum sensing (QS), we hypothesized that inhibition of P. aeruginosa with ibuprofen is linked with the QS systems. First, we assessed the action of ibuprofen in P. aeruginosa by measuring CFU. The antimicrobial activity of ibuprofen was evaluated by crystal violent staining and acridine orange staining at various drug concentrations (0, 50, 75, and 100 g/mL). Moreover, the effect of ibuprofen on different QS virulence factors, such as pyocyanin, elastase, protease, and rhamnolipids, was assessed revealing a concentration-dependent decrease (P<0.05). The effect of ibuprofen was confirmed by liquid chromatography/mass spectrometry analysis of 3-oxo-C12-HSL and C4-HSL production. In addition, qRT-PCR results identified significant suppression of Las and Rhl gene expression after 18 hours of treatment with ibuprofen (P<0.05), with the most significant suppression observed at the concentration of 75 g/mL. Functional complementation with exogenous 3-oxo-C12-HSL and C4-HSL suggested that C4-HSL can recover the production of virulence factors and biofilm formation in P. aeruginosa. Molecular docking of ibuprofen with QS-associated proteins revealed high binding affinity. In summary, the results suggest that ibuprofen is a candidate drug for the treatment of clinical infections with P. aeruginosa.

microbiology↗

Immunogenicity and protective potency of Norovirus GII.17 virus-like particle-based vaccine

Noroviruses (NoVs) are a major cause of acute viral gastroenteritis in adults and children worldwide. Lacking of cell culture system and animals models that must be considered the virus like particles (VLPs) used as an effective vaccine development. In the present study, we investigated the expression of the major capsid protein (VP1) of Genogroup II, genotype 17 (GII.17) NoV using recombinant baculovirus system in insect cells and saliva binding blockade assay to detect their protective potency. Our results showed that GII.17 VLPs could be successfully generated in sf9 insect cells and electron microscopic revealed that GII.17 VLPs was visualized as spherical particles of -35nm in diameter. Immunized mouse with purified VLPs produced GII.17 specific sera and could efficiently block GII.17 VLPs binding to saliva histo-blood group antigens (HBGAs). Together, these results suggested that GII.17 VLPs represent a promising vaccine candidate against NoV GII.17 infection and strongly support further preclinical and clinical studies.

immunology↗

Systems Biology Theory Clarification of a Controversy in Pancreatic Beta Cell Regeneration

Whether new pancreatic beta-cells arise via pre-existing beta-cells or from differentiation of precursor cells - a question of fundamental importance for diabetic therapy - has long been debated. Recent experiments suggest that multipotent precursors from adult mouse pancreas, that give rise to beta-cells, do exist. However, such a finding is at odds with prior evidence that beta-cell expansions occurs exclusively through self-replication. Here we show that these two observations can be partially compatible. We use a systems biology approach to analyze the dynamics of the endogenous molecular-cellular network in the pancreas. Our results show that self-replicating beta-cells can themselves be multipotent precursors. In addition, our model predicts heterogeneity in beta-cell regeneration and suggests various differentiation paths of precursors. This work therefore provides a means of reconciling an apparent contradiction in the field, but also sheds light on possible paths of beta-cell regeneration from a systems biology perspective.

systems biology↗

Complex dynamics in an SIS epidemic model induced by nonlinear incidence

We study an epidemic model with nonlinear incidence rate, describing the saturated mass action as well as the psychological effect of certain serious diseases on the community. Firstly, the existence and local stability of disease-free and endemic equilibria are investigated. Then, we prove the occurrence of backward bifurcation, saddle-node bifurcation, Hopf bifurcation and cusp type Bogdanov-Takens bifurcation of codimension 3. Finally, numerical simulations, including one limit cycle, two limit cycles, unstable homoclinic loop and many other phase portraits are presented. These results show that the psychological effect of diseases and the behavior change of the susceptible individuals may affect the final spread level of an epidemic.

epidemiology↗

Exogenous putrescine alleviates photoinhibition caused by salt stress through increasing cyclic electron flow in cucumber

When plants suffer from abiotic stresses, cyclic electron flow (CEF) is induced for photoprotection. Putrescine (Put), a main polyamine in chloroplasts, plays a critical role in stress tolerance. To elucidate the mechanism of Put regulating CEF for salt-tolerance in cucumber leaves, we measured chlorophyll fluorescence, P700 redox state, ATP and NADPH accumulation and so on. The maximum photochemical efficiency of PSII (Fv/Fm) was not influenced by NaCl and/or Put, but the activity of PSI reaction center (P700) was seriously inhibited by NaCl. Salt stress induced high level of CEF, moreover, NaCl and Put treated plants exhibited much higher CEF activity and ATP accumulation than single salt-treated plants to provide adequate ATP/NADPH ratio for plants growth. Furthermore, Put decreased the trans-membrane proton gradient ({Delta}pH), accompanied by reducing the pH-dependent non-photochemical quenching (qE) and increasing efficient quantum yield of PSII (Y(II)). The ratio of NADP+/NADPH in salt stressed leaves was significantly increased by Put, indicating that Put relieved over-reduction pressure at PSI accepter side. Taken together, our results suggest that exogenous Put enhances CEF to supply extra ATP for PSI recovery and CO2 assimilation, decreases {Delta}pH for electron transport related proteins staying active, and enable the non-photochemical quenching transformed into photochemical quenching.

plant biology↗