Assessment, mapping, and management of health risk from nitrate accumulation in onion for Iranian population.

Excess accumulation of nitrate in vegetable crops is normally related to the excessive use of nitrogen fertilizers applied in agricultural fields. This study was performed to evaluate the level of nitrate concentration in onion production in Isfahan province of Iran and the potential health risks associated with high level of nitrate in this crop, as an example of a case-study. The risk was estimated by using the United States Environmental Protection Agency (USEPA) method and presented as risk maps. Additionally, the impact of an improved fertilizer management practice in selected vulnerable fields for reducing nitrate concentration in onion production was evaluated. For this assessment, four different onion fields in which onion bulb nitrate concentration was higher than the safety level (70 mg kg-1 FW), provided by Welch (2003) in a survey study, were chosen. The risk maps showed that despite higher risk possibility in adults, in comparison with children, all values were lower than the acceptable level. Further, the split application of nitrogen fertilizers in all fields significantly reduced plant nitrate concentration with no reduction in yield and even observed increase in the overall economic yield production. Therefore, considering crop yields and nitrate accumulation impacts, improved nitrogen management could provide an opportunity to promote onion crop production while reducing negative health effects in high-risk regions in Isfahan province of Iran.

Root uptake and shoot accumulation of cadmium by lettuce at various Cd:Zn ratios in nutrient solution.

Cadmium (Cd) is toxic to animals and humans after it accumulates over decades in the kidney cortex. Food crops grown in Cd-contaminated soils are the primary sources of excessive Cd entry into humans. Although plant available Zn concentration in soil is an important factor which can greatly reduce Cd uptake by plant roots and its translocation into the edible parts, Cd:Zn ratio is suggested to be a more important factor in comparison with Zn concentration alone in determining Cd uptake by plants. In the present study, the physiological mechanisms of Cd absorption by roots and its translocation to leaves of lettuce (Lactuca sativa L.) at various Cd:Zn ratios in the rooting media were investigated. For this purpose, seedlings of hydroponically-grown lettuce were exposed to combinations of four Zn (0, 12.5, 50 and 100µM) and four Cd (0, 0.5, 1 and 10µM) concentrations providing different ratios of Cd:Zn. At each level of Cd, decreasing the Cd:Zn ratio by increasing Zn concentration in the nutrient solution caused significant reduction of root symplastic Cd and also reduced Cd loading into the xylem and Cd transport to and accumulation in leaves. The highest root symplastic Cd (1087mg/kg-1 Dry Weight [DW]) and shoot Cd concentrations (64mg/kg-1 DW) were observed at the highest Cd:Zn ratio of = 0.8 (Zn = 12.5, Cd = 10). At the Cd:Zn ratios of ≤ 0.01, shoot Cd concentration was less than the Detection Limit (< 0.02mg/kg DW). Decreasing Cd:Zn ratio in nutrient solution was accompanied with significant increase in root apoplastic Cd and decrease in the root symplastic Cd. According to the obtained results, at the Cd:Zn ratio equal to 0.01 and less, Cd concentration in lettuce shoots decreased to < 0.02mg/kg.

Antiviral gene expression in psoriasis.

BACKGROUND: Psoriasis patients have relatively infrequent cutaneous viral infections compared to atopic dermatitis patients. Increased expression of four antiviral proteins (MX1, BST2, ISG15 and OAS2) has been reported in psoriatic skin and genetic studies of psoriasis have identified susceptibility genes in antiviral pathways. OBJECTIVE: To determine if psoriasis is associated with pervasive expression of antiviral genes in skin and blood. METHODS: We performed RNA sequencing on skin samples of 18 subjects with chronic plaque psoriasis and 16 healthy controls. We examined the expression of a predefined set of 42 antiviral genes, each of which has been shown in previous studies to inhibit viral replication. In parallel, we examined antiviral gene expression in atopic dermatitis, non-lesional psoriatic skin and psoriatic blood. We performed HIV-1 infectivity assays in CD4+ peripheral blood T cells from psoriatic and healthy individuals. RESULTS: We observed significant overexpression of 16 antiviral genes in lesional psoriatic skin, with a greater than two-fold increase in ISG15, RSAD2, IRF7, MX2 and TRIM22 (P < 1E-07). None of these genes was overexpressed in atopic dermatitis skin (P < 0.0001) or non-lesional psoriatic skin. In contrast to the skin compartment, no differences in antiviral gene expression were detected in the peripheral blood of psoriasis cases compared to healthy controls. CD4+ T cells from both psoriatic and healthy patients supported HIV-1 infection at a similar rate. CONCLUSION: Our findings highlight psoriasis as an inflammatory disease with cutaneous but not systemic immune activation against viral pathogens.