ABSTRACT
The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is raging across the world, leading to a global mortality rate of 3.4% (estimated by World Health Organization in March 2020). As a potential vaccine and therapeutic target, the nucleocapsid protein of SARS-CoV-2 (nCoVN) functions in packaging the viral genome and viral self-assembly. To investigate the biological effects of nCoVN to human stem cells, genetically engineered human induced pluripotent stem cells (iPSC) expressing nCoVN (iPSC-nCoVN) were generated by lentiviral expression systems, in which the expression of nCoVN could be induced by the doxycycline. The proliferation rate of iPSC-nCoVN was decreased. Unexpectedly, the morphology of iPSC started to change after nCoVN expression for 7 days. The pluripotency marker TRA-1-81 were not detectable in iPSC-nCoVN after a four-day induction. Meanwhile, iPSC-nCoVN lost the ability for differentiation into cardiomyocytes with a routine differentiation protocol. The RNA-seq data of iPSC-nCoVN (induction for 30 days) and immunofluorescence assays illustrated that iPSC-nCoVN were turning to fibroblast-like cells. Our data suggested that nCoVN disrupted the pluripotent properties of iPSC and turned them into other types of cells, which provided a new insight to the pathogenic mechanism of SARS-CoV-2.
ABSTRACT
This study was aimed to establish the quality standard of Pyrethri Tatsienenis Flos. The medical material was identified by the microscopy and the thin layer chromatography ( TLC ) methods . The moisture , total ash , acid-insoluble ash and alcohol-soluble extract were determined according to procedures recorded in the Chi-nese Pharmacopoeia (2010 edition). The content of luteolin was determined by the HPLC method. The results showed a strong characteristic microscopic of Pyrethri Tatsienenis Flos , and its TLC identification had a good resolution with clear spots . The mass fractions of luteolin was 0 . 036%~0 . 104% ( average of 0 . 078%) , moisture was 9 . 32%~15 . 82% ( average of 13 . 11%) , total ash was 6 . 65%~8 . 29% ( average of 7 . 45%) , acid-insoluble ash was 0 . 23%~0 . 59% ( average of 0 . 42%) , and the extraction was 21 . 42%~30 . 15% ( average of 24 . 86%) . It was concluded that this established standard was simple to operate with good stability and reproducibility , which can be used for quality evaluation of Pyrethri Tatsienenis Flos .