Dysfunctional immune response in the COVID-19 patients is a recurrent theme impacting symptoms and mortality, yet the detailed understanding of pertinent immune cells is not complete. We applied single-cell RNA sequencing to 284 samples from 196 COVID-19 patients and controls and created a comprehensive immune landscape with 1.46 million cells. The large dataset enabled us to identify that different peripheral immune subtype changes were associated with distinct clinical features including age, sex, severity, and disease stages of COVID-19. SARS-CoV-2 RNAs were found in diverse epithelial and immune cell types, accompanied by dramatic transcriptomic changes within viral positive cells. Systemic up-regulation of S100A8/A9, mainly by megakaryocytes and monocytes in the peripheral blood, may contribute to the cytokine storms frequently observed in severe patients. Our data provide a rich resource for understanding the pathogenesis and developing effective therapeutic strategies for COVID-19.

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5-Aminolevulinic acid (ALA), a nonprotein amino acid involved in tetrapyrrole synthesis, has been widely applied in agriculture, medicine, and food production. Many engineered metabolic pathways have been constructed; however, the production yields are still low. In this study, several 5-aminolevulinic acid synthases (ALASs) from different sources were evaluated and compared with respect to their ALA production capacities in an engineered Corynebacterium glutamicum CgS1 strain that can accumulate succinyl-coenzyme A (CoA). A codon-optimized ALAS from Rhodobacter capsulatus SB1003 displayed the best potential. Recombinant strain CgS1/pEC-SB produced 7.6 g/liter ALA using a mineral salt medium in a fed-batch fermentation mode. Employing two-stage fermentation, 12.46 g/liter ALA was produced within 17 h, with a productivity of 0.73 g/liter/h, in recombinant C. glutamicum. Through overexpression of the heterologous nonspecific ALA exporter RhtA from Escherichia coli, the titer was further increased to 14.7 g/liter. This indicated that strain CgS1/pEC-SB-rhtA holds attractive industrial application potential for the future. IMPORTANCEIn this study, a two-stage fermentation strategy was used for production of the value-added nonprotein amino acid 5-aminolevulinic acid from glucose and glycine in a generally recognized as safe (GRAS) host, Corynebacterium glutamicum. The ALA titer represented the highest in the literature, to our knowledge. This high production capacity, combined with the potential easy downstream processes, made the recombinant strain an attractive candidate for industrial use in the future.A s the common precursor of tetrapyrroles such as porphyrin, heme, vitamin B 12 , and chlorophyll, 5-aminolevulinic acid (ALA) has been reported to be effective in tumor-localizing and photodynamic therapy for various diseases (1-3). ALA can also be used as a selective biodegradable herbicide and insecticide or an adversity resistance and growth-accelerating agent in agriculture (4, 5).In living organisms, two kinds of metabolic pathways have been described for ALA biosynthesis (Fig. 1). One is the C 5 pathway, which occurs in algae, higher plants, and many bacteria, including Escherichia coli and archaea. The C 5 pathway involves the following three enzymatic activities: glutamyl-tRNA synthetase (GluRS) (encoded by gltX), a NADPH-dependent glutamyl-tRNA reductase (HemA, encoded by hemA), and a glutamate-1-semialdehyde aminotransferase (HemL, encoded by hemL). The other is the C 4 pathway, which is present in birds, mammals, yeast, and purple non-sulfur-photosynthetic bacteria. In this pathway, ALA is formed through one-step catalysis by 5-aminolevulinic acid synthase (ALAS), which condenses glycine and succinyl-coenzyme A (CoA), an intermediate of the tricarboxylic acid (TCA) cycle.In E. coli, the native pathway for ALA biosynthesis is the C 5 pathway, which is tightly regulated by feedback inhibition of the end product heme (6). Previously, we developed a strategy to produce ALA in recombinant E. coli vi...

Biomedical application potentials of carbon nanotubes-based materials have been investigated intensively in recent years; however, characterization and metrology are still facing great technical challenges when the materials are intended to be used as carriers for therapeutics in aqueous solutions. Systematic characterization on the dispersing carbon nanotubes is urgently required and therefore of significance. In this paper multiwalled carbon nanotubes (MWCNTs) with different average lengths or with different oxidation degrees were dispersed in water and characterized systematically by applying UV spectroscopy, SEM, DLS, TGA, XPS, and FTIR. In particular, the characteristic absorption of the carbon nanotubes was analyzed using resolution-fitting technique to establish relations of wavelength and absorption intensity to the size distribution and surface chemistry. Results indicated that the absorption spectra of MWCNTs could reflect the variation of surface chemistry and length distribution of carbon nanotubes dispersed in water by combining with the other measurements. A vascular endothelium cell line was taken as a model to figure out association between physicochemical features and cytotoxicity of the carbon nanotubes. It was showed that the multiwalled carbon nanotubes with different oxidation degrees and similar length distribution exhibited different interaction files to the cells proliferation in a manner of time dependence and concentration dependence.