The RNA helicase DDX5 promotes viral infection via regulating N6-methyladenosine levels on the DHX58 and NFκB transcripts to dampen antiviral innate immunity.

Multi-functional DEAD-box helicase 5 (DDX5), which is important in transcriptional regulation, is hijacked by diverse viruses to facilitate viral replication. However, its regulatory effect in antiviral innate immunity remains unclear. We found that DDX5 interacts with the N6-methyladenosine (m6A) writer METTL3 to regulate methylation of mRNA through affecting the m6A writer METTL3-METTL14 heterodimer complex. Meanwhile, DDX5 promoted the m6A modification and nuclear export of transcripts DHX58, p65, and IKKγ by binding conserved UGCUGCAG element in innate response after viral infection. Stable IKKγ and p65 transcripts underwent YTHDF2-dependent mRNA decay, whereas DHX58 translation was promoted, resulting in inhibited antiviral innate response by DDX5 via blocking the p65 pathway and activating the DHX58-TBK1 pathway after infection with RNA virus. Furthermore, we found that DDX5 suppresses antiviral innate immunity in vivo. Our findings reveal that DDX5 serves as a negative regulator of innate immunity by promoting RNA methylation of antiviral transcripts and consequently facilitating viral propagation.

Crop selection reduces potential heavy metal(loid)s health risk in wastewater contaminated agricultural soils.

Vegetable crops have varied heavy metal(loid)s accumulation rates from soils to their edible tissues. However, crop selection has been seldom evaluated as a strategy for reducing the health risks of ingesting vegetables grown in soils contaminated by treated wastewater (TWW) irrigation. We cultivated twenty commonly grown vegetables using soils with an approximately 50-year history of TWW irrigation, and their ingestion risks were evaluated by the health risk index (HRI). Results showed that twenty vegetable species had varied abilities in accumulating heavy metal(loid)s from soils to their edible parts (e.g., >100 times of difference for Cd). We found higher potential health risks (HRI > 1) due to As, Cd, and Pb for adults ingesting few vegetable species and all the studied vegetables had negligible health risks (HRI < 1) for Cr, Cu, and Zn. These results suggest that remediation strategies should be targeted towards As, Cd, and Pb removal in agricultural soils in this region. Total HRI > 5 was obtained for ingesting spinach, Chinese lettuce, and Chinese chives, suggesting a high potential of severe health risks. Negligible risks (total HRI < 1) were found for tomato, kidney bean, potato, and cabbage. Our study highlights crop selection as a feasible strategy for ensuring food safety in TWW contaminated farmlands.

Coupling sprinkler freshwater irrigation with vegetable species selection as a sustainable approach for agricultural production in farmlands with a history of 50-year wastewater irrigation.

Soil contamination and crop risks of heavy metal(loid)s are widely reported after the long-term irrigation of treated wastewater, causing an adverse influence on agricultural sustainability. Here, we collected soils after 50 years of wastewater irrigation to cultivate cabbage (Brassica pekinensis L.), rape (Brassica chinensis L.), carrots (Daucus carota L.), and potatoes (Solanum tuberosum L.), using surface and sprinkler irrigation with freshwater and wastewater. In general, we found the statistically insignificant influence of short-term freshwater irrigation on the soil and vegetable metal(loid) concentrations. Most of the vegetables had potential adverse health risks with the relatively lower risks in carrots and potatoes, and most of the risks were contributed by As and Cd. Nevertheless, we observed negligible health risks for all studied metal(loid)s in potatoes under the freshwater irrigations. Besides, compared to wastewater irrigations, freshwater irrigations produced lower Cd health risks in all four vegetable species. Sprinkler irrigation with freshwater was a favorable approach for reducing the uptake of metal(loid)s from soils and the metal(loid) concentrations in aboveground parts. Our study highlights the possibility of reducing vegetable metal(loid) risks in contaminated farmlands via a combined approach of coupling the short-term decrease in their levels in irrigation water with vegetable species selection.

DEAD/DEAH-box helicase 5 is hijacked by an avian oncogenic herpesvirus to inhibit interferon beta production and promote viral replication.

DEAD-box helicase 5 (DDX5) plays a significant role in tumorigenesis and regulates viral replication of several viruses. An avian oncogenic herpesvirus, Marek's disease virus (MDV), is widely known to cause immunosuppression and lymphoma in chickens. However, the underlying mechanisms of how DDX5 plays a role in viral replication remain unclear. In this study, we show that MDV inhibits the production of interferon beta (IFN-ß) in chicken embryo fibroblasts (CEFs) by increasing the expression level and promoting the nuclear aggregation of DDX5. We further reveal how DDX5 down-regulates melanoma differentiation-associated gene 5/toll-like receptor 3 signaling through the fundamental transcription factor, interferon regulatory factor 1. MDV replication is suppressed, and the production of IFN-ß is promoted in the DDX5 absented CEFs. Taken together, our investigations demonstrate that MDV inhibits IFN-ß production by targeting DDX5-mediated signaling to facilitate viral replication, which offers a novel insight into the mechanism by which an avian oncogenic herpesvirus replicates in chicken cells.

Dynamics of multiple elements in fast decomposing vegetable residues.

Litter decomposition regulates the cycling of nutrients and toxicants but is poorly studied in farmlands. To understand the unavoidable in-situ decomposition process, we quantified the dynamics of C, H, N, As, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, and Zn during a 180-d decomposition study in leafy lettuce (Lactuca sativa var. longifoliaf) and rape (Brassica chinensis) residues in a wastewater-irrigated farmland in northwestern China. Different from most studied natural ecosystems, the managed vegetable farmland had a much faster litter decomposition rate (half-life of 18-60d), and interestingly, faster decomposition of roots relative to leaves for both the vegetables. Faster root decomposition can be explained by the initial biochemical composition (more O-alkyl C and less alkyl and aromatic C) but not the C/N stoichiometry. Multi-element dynamics varied greatly, with C, H, N, K, and Na being highly released (remaining proportion<20%), Ca, Cd, Cr, Mg, Ni, and Zn released, and As, Cu, Fe, Hg, Mn, and Pb possibly accumulated. Although vegetable residues serve as temporary sinks of some metal(loid)s, their fast decomposition, particularly for the O-alkyl-C-rich leafy-lettuce roots, suggest that toxic metal(loid)s can be released from residues, which therefore become secondary pollution sources.

Greenhouse cultivation mitigates metal-ingestion-associated health risks from vegetables in wastewater-irrigated agroecosystems.

Wastewater irrigation can elevate metal concentrations in soils and crops and increase the metal-associated health risks via vegetable ingestion in arid and semiarid northwestern China. Here, we investigated the As, Cd, Cr, Cu, Ni, Pb, and Zn concentrations in four vegetable species from Dongdagou and Xidagou farmlands in Baiyin, Gansu, China. We evaluated the effects of irrigation type (Dongdagou: industrial wastewater; Xidagou: domestic wastewater) and cultivation mode (open field and greenhouse) on the vegetable metal concentration, metal partitioning, soil-to-plant bioconcentration factor (BCF), and the health risk index. All stream waters, soils, and vegetables were found most severely polluted by As and Cd, with higher severity in the industrial-wastewater-irrigated Dongdagou than the domestic-wastewater-irrigated Xidagou. All vegetables had higher or, at least, comparable metal mass allocated in the shoot than in the root. Greenhouse cultivation could reduce metal-ingestion-associated health risks from edible vegetable biomass by decreasing the soil to plant bioaccumulation (BCF) and the metal concentration. This effect was always significant for all vegetables within Xidagou, and for carrot within Dongdagou. This mitigation effect of greenhouse cultivation could be attributed to the metal sorption by a higher level of soil organic matter and faster growth rate over metal uptake rate in greenhouses compared to open fields. Such mitigation effect was, however, insignificant for leafy vegetables within Dongdagou, when much more severely polluted water for irrigation was applied in greenhouses compared to open fields within Dongdagou. The present study highlights greenhouse cultivation as a potential mitigating approach to providing less-polluted vegetables for residents in the severely polluted area in addition to the source pollution control.