We applied stable carbon isotopes,ultraviolet-visible absorption(UV-Vis),fluorescence excitation-emission matrices spectroscopy(EEMs),and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS)to invest...
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We applied stable carbon isotopes,ultraviolet-visible absorption(UV-Vis),fluorescence excitation-emission matrices spectroscopy(EEMs),and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS)to investigate the chemical composition and sources of the dissolved organic matter(DOM)in both the water column and pore water in Xiangshan Bay,a representative semi-enclosed and eutrophic bay in Zhejiang Province,*** protein-like fluorescent component(C1)and two humic-like fluorescent components(C2 and C3)were identified by PARAFAC *** concentration of dissolved organic carbon(DOC),the relative intensities of C2,C3,and black carbon-like compounds are all negatively correlated with salinity,indicating that there is a dilution effect of terrestrial signals by seawater in Xiangshan *** differences in light penetration ability of Xiangshan Bay cause different degrees of photo-degradation,which may play an important role in the transformation of organic matter in Xiangshan *** weak correlation between the C1 fluorescent component and salinity indicates that autochthonous sources cannot dominate the protein-like FDOM in the Xiangshan Bay drainage *** sources(such as anthropogenic inputs and release of pore water)also affect the distribution of the protein-like fluorescent component under eutrophication *** relative proportion of the protein-like fluorescent component in Xiangshan Bay is on a medium level in China and anthropogenic inputs may be a significant source of DOM in coastal bays.
Newcastle disease virus (NDV) fusion protein mediates the virus's fusion activity, which is a determinant of NDV pathogenicity. The ectodomain of the F protein is known to have a major impact on fusion, and severa...
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Newcastle disease virus (NDV) fusion protein mediates the virus's fusion activity, which is a determinant of NDV pathogenicity. The ectodomain of the F protein is known to have a major impact on fusion, and several reports have also indicated the role of the cytoplasmic tail (CT) in viral entry, F protein cleavage, and fusion, which are regulated by specific motifs. We found a highly conserved tyrosine residue located in the YLMY motif. The tyrosine residues at positions 524 and 527 have different roles in viral replication and pathogenicity and are associated with F protein intracellular processing. Tyrosine residues mutants affect the transportation of the F protein from the endoplasmic reticulum to the Golgi apparatus, resulting in different cleavage efficiencies. F protein is subsequently transported to the cell surface where it participates in viral budding, a process closely related to the distinctions in pathogenicity caused by the tyrosine residues. In addition, the different mutations all led to a hypofusogenic phenotype. We believe that the highly conserved tyrosine residue of the YLMY motif uses a similar mechanism to the tyrosine-based motif (YXXU) to regulate F protein transport and thus affect viral replication and pathogenicity. IMPORTANCE The amino-terminal cytoplasmic domains of paramyxovirus fusion glycoproteins include trafficking signals that influence protein processing and cell surface expression. This study clarified that tyrosine residues at different positions in the YLMY motif in the cytoplasmic region of the F protein regulate F protein transportation, thereby affecting viral replication and pathogenicity. This study has increased our understanding of how NDV virulence is mediated by the F protein and provides a fresh perspective on the role of CT in the virus's life cycle. This information may be useful in the development of NDV as an effective vaccine vector and oncolytic agent.
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