DDX23 of black carp negatively regulates MAVS-mediated antiviral signaling in innate immune activation.

Mammalian DDX23 is involved in multiple biological processes, such as RNA processing and antiviral responses. However, the function of teleost DDX23 still remains unclear. In this paper, we have cloned the DDX23 homologue of black carp (Mylopharyngodon piceus) (bcDDX23) and elucidated its role in the antiviral innate immunity. The coding region of bcDDX23 comprises 2427 nucleotides and encodes 809 amino acids. The transcription of bcDDX23 was promoted by the stimulation of LPS, poly(I:C), and SVCV; and immunoblotting (IB) assay showed that bcDDX23 migrated aground 94.5 kDa. Immunofluorescence (IF) assay revealed that bcDDX23 was mainly distributed in the nucleus, and the amount of cytosolic bcDDX23 was significantly increased after SVCV infection. The reporter assay showed that bcDDX23 inhibited bcMAVS-mediated transcription of the IFN promoter. And the co-immunoprecipitation (co-IP) assays identified the interaction between bcDDX23 and bcMAVS. Furthermore, co-expressed bcDDX23 significantly inhibited bcMAVS-mediated antiviral ability against SVCV in EPC cells, and knockdown of bcDDX23 enhanced the resistance of host cells against SVCV. Overall, our results conclude that bcDDX23 targets bcMAVS and suppresses MAVS-mediated IFN signaling, which sheds light on the regulation of IFN signaling in teleost fish.

[Effects of different levels of vitamin C on UV radiation-induced DNA damage].

The Raman spectra of DNA in different levels of vitamin C with 10 min ultraviolet radiation and 30 min ultraviolet radiation were reported. The intensity of ultraviolet radiation was 18.68 W x m(-2). The experimental results proved that vitamin C can reduce DNA damage solely, but the effects are related to the concentration of vitamin C. When the concentration of vitamin C was lower than 0.35 mmol x L(-1), DNA was protected better with the rising of vitamin C concentration during ultraviolet radiation. DNA was protected best when vitamin C was 0.35 mmol x L(-1). When vitamin C concentration was higher than 0.35 mmol x L(-1), vitamin C accelerated DNA damage with 10 min ultraviolet radiation. But DNA was also protected with 30 min ultraviolet radiation as vitamin C was 0.35-0.65 mmol x L(-1). However, DNA was only protected slightly at high concentration of vitamin C.