Browsing by Author "Wang, Nian"
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Item Open Access A plant genetic network for preventing dysbiosis in the phyllosphere.(Nature, 2020-04-08) Chen, Tao; Nomura, Kinya; Wang, Xiaolin; Sohrabi, Reza; Xu, Jin; Yao, Lingya; Paasch, Bradley C; Ma, Li; Kremer, James; Cheng, Yuti; Zhang, Li; Wang, Nian; Wang, Ertao; Xin, Xiu-Fang; He, Sheng YangThe aboveground parts of terrestrial plants, collectively called the phyllosphere, have a key role in the global balance of atmospheric carbon dioxide and oxygen. The phyllosphere represents one of the most abundant habitats for microbiota colonization. Whether and how plants control phyllosphere microbiota to ensure plant health is not well understood. Here we show that the Arabidopsis quadruple mutant (min7 fls2 efr cerk1; hereafter, mfec)1, simultaneously defective in pattern-triggered immunity and the MIN7 vesicle-trafficking pathway, or a constitutively activated cell death1 (cad1) mutant, carrying a S205F mutation in a membrane-attack-complex/perforin (MACPF)-domain protein, harbour altered endophytic phyllosphere microbiota and display leaf-tissue damage associated with dysbiosis. The Shannon diversity index and the relative abundance of Firmicutes were markedly reduced, whereas Proteobacteria were enriched in the mfec and cad1S205F mutants, bearing cross-kingdom resemblance to some aspects of the dysbiosis that occurs in human inflammatory bowel disease. Bacterial community transplantation experiments demonstrated a causal role of a properly assembled leaf bacterial community in phyllosphere health. Pattern-triggered immune signalling, MIN7 and CAD1 are found in major land plant lineages and are probably key components of a genetic network through which terrestrial plants control the level and nurture the diversity of endophytic phyllosphere microbiota for survival and health in a microorganism-rich environment.Item Open Access Characterization complex collagen fiber architecture in knee joint using high-resolution diffusion imaging.(Magnetic resonance in medicine, 2020-01-21) Wang, Nian; Mirando, Anthony J; Cofer, Gary; Qi, Yi; Hilton, Matthew J; Johnson, G AllanPURPOSE:To evaluate the complex fiber orientations and 3D collagen fiber network of knee joint connective tissues, including ligaments, muscle, articular cartilage, and meniscus using high spatial and angular resolution diffusion imaging. METHODS:Two rat knee joints were scanned using a modified 3D diffusion-weighted spin echo pulse sequence with the isotropic spatial resolution of 45 μm at 9.4T. The b values varied from 250 to 1250 s/mm2 with 31 diffusion encoding directions for 1 rat knee. The b value was fixed to 1000 s/mm2 with 147 diffusion encoding directions for the second knee. Both the diffusion tensor imaging (DTI) model and generalized Q-sampling imaging (GQI) method were used to investigate the fiber orientation distributions and tractography with the validation of polarized light microscopy. RESULTS:To better resolve the crossing fibers, the b value should be great than or equal to 1000 s/mm2 . The tractography results were comparable between the DTI model and GQI method in ligament and muscle. However, the tractography exhibited apparent difference between DTI and GQI in connective tissues with more complex collagen fibers network, such as cartilage and meniscus. In articular cartilage, there were numerous crossing fibers found in superficial zone and transitional zone. Tractography generated with GQI also resulted in more intact tracts in articular cartilage than DTI. CONCLUSION:High-resolution diffusion imaging with GQI method can trace the complex collagen fiber orientations and architectures of the knee joint at microscopic resolution.