Aridity creates global thresholds in soil nitrogen retention and availability.

Identifying tipping points in the relationship between aridity and gross nitrogen (N) cycling rates could show critical vulnerabilities of terrestrial ecosystems to climate change. Yet, the global pattern of gross N cycling response to aridity across terrestrial ecosystems remains unknown. Here, we collected 14,144 observations from 451 15 N-labeled studies and used segmented regression to identify the global threshold responses of soil gross N cycling rates and soil process-related variables to aridity index (AI), which decreases as aridity increases. We found on a global scale that increasing aridity reduced soil gross nitrate consumption but increased soil nitrification capacity, mainly due to reduced soil microbial biomass carbon (MBC) and N (MBN) and increased soil pH. Threshold response of gross N production and retention to aridity was observed across terrestrial ecosystems. In croplands, gross nitrification and extractable nitrate were inhibited with increasing aridity below the threshold AI ~0.8-0.9 due to inhibited ammonia-oxidizing archaea and bacteria, while the opposite was favored above this threshold. In grasslands, gross N mineralization and immobilization decreased with increasing aridity below the threshold AI ~0.5 due to decreased MBN, but the opposite was true above this threshold. In forests, increased aridity stimulated nitrate immobilization below the threshold AI ~1.0 due to increased soil C/N ratio, but inhibited ammonium immobilization above the threshold AI ~1.3 due to decreased soil total N and increased MBC/MBN ratio. Soil dissimilatory nitrate reduction to ammonium decreased with increasing aridity globally and in forests when the threshold AI ~1.4 was passed. Overall, we suggest that any projected increase in aridity in response to climate change is likely to reduce plant N availability in arid regions while enhancing it in humid regions, affecting the provision of ecosystem services and functions.

Long-Term Feeding with Curcumin Affects the Growth, Antioxidant Capacity, Immune Status, Tissue Histoarchitecture, Immune Expression of Proinflammatory Cytokines, and Apoptosis Indicators in Nile Tilapia, Oreochromis niloticus.

The impact of dietary curcumin (CUR) on the growth, antioxidant activity, histomorphology of certain organs, proinflammatory cytokine production, and immune status of Oreochromis niloticus was evaluated. The fingerlings (n = 225, 41.60 ± 0.09 g/fish) were randomly allotted into five experimental groups in triplicate. Fish were fed basal diets complemented with 0, 200, 400, 600, or 800 mg curcumin/kg diet (CUR0, CUR200, CUR400, CUR600, and CUR800, respectively) for 10 weeks. An increase in fish growth was reported in the CUR200 and CUR400 groups. The feed conversion ratio was enhanced by 15% in the CUR400 group. Fish body protein content was increased in the CUR600 group (p ≤ 0.01). Body fat was decreased, and ash content was increased by CUR supplementation in a level-related way (p < 0.05). The villus height was increased in the CUR400 and CUR600 groups. The villus width was increased by CUR supplementation, with the best result found in the CUR600 group. The liver of CUR-fed fish displayed comparatively normal hepatocytes. TNF-α and caspase-3 were significantly upregulated by dietary CUR in a level-related way. The serum catalase activity and GSH level were increased in CUR200 and CUR400 groups. Curcumin supplementation boosted the serum SOD activity and reduced the MDA level. IL10 and IgM levels were increased in the CUR200 and CUR400 groups. Lysozyme activity was increased in the CUR200−400 groups. Serum complement 3 level was increased in the CUR400 group. The percentage survival of O. niloticus challenged with Aeromonas hydrophila was highest in the CUR200-CUR600 groups (100%) and decreased in the CUR800 group (80%). This study concluded that CUR could be added to Nile tilapia diets up to 400 mg·kg−1 to achieve better growth, antioxidant capacity, immune response, and intestinal histology. Long feeding periods on high levels of CUR (600 and 800 mg·kg−1) stimulate inflammatory reactions in fish tissues.

Mitigate nitrate contamination in potato tubers and increase nitrogen recovery by combining dicyandiamide, moringa oil and zeolite with nitrogen fertilizer.

Potato is considered a nitrogen (N) intensive plant with a low N use efficiency (NUE). The current study introduced an excellent approach by combining dicyandiamide (DCD), moringa seed oil (MSO), or zeolite (ZE), with N fertilizer for maximizing potato tuber yields and NUE as well as minimizing tubers nitrate (NO3-) accumulation. The impact of these materials on soil N availability and gaseous emissions (NH3, and N2O) was investigated under incubation conditions. A 2-year field experiment were carried out with seven treatments [without N (control), N fertilizer (350 kg N-urea ha-1 as a recommended dose; UreaRD), 75% of N recommended dose with DCD (Urea75%RD+DCD), Urea75%RD with 2% MSO (Urea75%RD+MSO2%), Urea75%RD with 4% MSO (Urea75%RD+MSO4%), Urea75%RD with 0.5 Mg ZE ha-1 (Urea75%RD+ZER1), and Urea75%RD with 1.0 Mg ZE ha-1 (Urea 75%RD+ZER2)]. We also conducted a 40-days incubation trial with the same treatments; however, urea was added at the rate of 200 mg N kg-1 soil for all treatments, excluding the control. The addition of DCD, MSO, and ZE with urea under incubation conditions delayed the nitrification process, thereby causing a rise in NH4+-N content and a decrease in NO3--N content. Ammonia-oxidizing bacteria (AOB) was inhibited (p ≤ 0.01) in treatments Urea+DCD, Urea+MSO4%, and Urea+ZER2. The highest NUE indexes were recorded in treatment Urea75%RD+DCD. The highest NO3- accumulation (567 mg NO3- kg-1) in potato tubers was recorded in treatment UreaRD. Whilest, the lowest NO3- content (81 mg NO3- kg-1) was in treatment Urea75%RD+DCD. The lowest cumulative N2O emissions and highest cumulative NH3 volatilization were observed in the treatment Urea+DCD under incubation conditions. Our findings demonstrated that N fertilizer rate could be reduced by 25%, while the tuber yields increased with an acceptable limit of NO3- content, resulting in economical, agronomical, and environmental benefits.

Ringworm in calves: risk factors, improved molecular diagnosis, and therapeutic efficacy of an Aloe vera gel extract.

BACKGROUND: Dermatophytosis in calves is a major public and veterinary health concern worldwide because of its zoonotic potential and associated economic losses in cattle farms. However, this condition has lacked adequate attention; thus, to develop effective control measures, we determined ringworm prevalence, risk factors, and the direct-sample nested PCR diagnostic indices compared with the conventional methods of dermatophytes identification. Moreover, the phenolic composition of an Aloe vera gel extract (AGE) and its in vitro and in vivo antidermatophytic activity were evaluated and compared with those of antifungal drugs. RESULTS: Of the 760 calves examined, 55.79% (424/760) showed ringworm lesions; 84.91% (360/424) were positive for fungal elements in direct-microscopy, and 79.72% (338/424) were positive in culture. Trichophyton verrucosum was the most frequently identified dermatophyte (90.24%). The risk of dermatophytosis was higher in 4-6-month-old vs. 1-month-old calves (60% vs. 41%), and in summer and winter compared with spring and autumn seasons (66 and 54% vs. 48%). Poor hygienic conditions, intensive breeding systems, animal raising for meat production, parasitic infestation, crossbreeding, and newly purchased animals were statistically significant risk factors for dermatophytosis. One-step PCR targeting the conserved regions of the 18S and 28S genes achieved unequivocal identification of T. verrucosum and T. mentagrophytes in hair samples. Nested-PCR exhibited an excellent performance in all tested diagnostic indices and increased the species-specific detection of dermatophytes by 20% compared with culture. Terbinafine and miconazole were the most active antifungal agents for dermatophytes. Gallic acid, caffeic acid, chlorogenic acid, cinnamic acid, aloe-Emodin, quercetin, and rutin were the major phenolic compounds of AGE, as assessed using high-performance liquid chromatography (HPLC). These compounds increased and synergized the antidermatophytic activity of AGE. The treated groups showed significantly lower clinical scores vs. the control group (P < 0.05). The calves were successfully treated with topical AGE (500 ppm), resulting in clinical and mycological cure within 14-28 days of the experiment; however, the recovery was achieved earlier in the topical miconazole 2% and AGE plus oral terbinafine groups. CONCLUSIONS: The nested PCR assay provided a rapid diagnostic tool for dermatophytosis and complemented the conventional methods for initiating targeted treatments for ringworm in calves. The recognized antidermatophytic potential of AGE is an advantageous addition to the therapeutic outcomes of commercial drugs.

Can secondary metabolites extracted from Moringa seeds suppress ammonia oxidizers to increase nitrogen use efficiency and reduce nitrate contamination in potato tubers?

Nitrification inhibition as an alleviation tool to decrease nitrogen (N) losses and increase N use efficiency (NUE) as well as reducing NO3- accumulation in plants is a promising technology. No study thus far has directly or indirectly to use the secondary metabolites extracted from Moringa (Moringa oleifera Lam) seeds as nitrification inhibitors. Moringa seed extract (MSE) was studied based on its content of phenolic compounds (PC) and for its antioxidant characteristic. A 2-year field experiment and 30-day incubation experiment were conducted with three treatments of control (CK), N fertilizer (300 kg N ha-1 and 200 mg N kg-1 soil for the field and incubation experiment, respectively), and N fertilizer with MSE (500 ppm as a TPC) to investigate the responses of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to MSE and the consequences for NUE and NO3- accumulation in potato tubers. Total phenolics amount was 144 mg gallic acid equivalent g-1 MSE, while flavonoid contents were 76.6 quercetin equivalent g-1 MSE. MSE showed antioxidant activity that was comparable to the standard antioxidants TBHQ and gallic acid. MSE application with N fertilizer retarded the nitrification process, as indicated by a higher NH4+-N and lower NO3--N content, compared with N fertilizer application alone. NH4+-N content reduced to initial CK level on Day 20 under N fertilizer application alone. However, NH4+-N content decreased to initial control level on Day 30 when MSE was applied. The mechanisms resulted from curbing AOB growth by phenolic compounds (TPC, TF, TAC), leading to a delay in nitrification process. AOB increased significantly when N fertilizer was applied alone; on the contrary, AOA was not sensitive to N fertilizer (with and without MSE). Increase in NUE from 37.5% to 66.3% in potato plants under MSE application with N fertilizer was also observed compared with N fertilizer application alone. The highest NO3- accumulation (569 mg NO3- kg-1) in tubers was recorded under N fertilizer application without MSE. MSE application significantly decreased NO3- accumulation (92 mg NO3- kg-1) in tubers which is lower than the maximum value of accepting tubers (200 mg NO3- kg-1). The highest average of N uptake, fresh and dry weight, carotenoids, chlorophyll a, chlorophyll b and nitrate reductase activity was recorded when MSE was applied with N fertilizer. Accordingly, using of Moringa extracted secondary metabolites to suppress AOB growth in the soil is a significant strategy to reduce nitrification rate and N loss from soils, and therefore increase NUE as well as reducing NO3- accumulation in potato tubers.

Interplaying roles of silicon and proline effectively improve salt and cadmium stress tolerance in Phaseolus vulgaris plant.

The interplaying defensive roles of silicon (Si) and proline (Pro) in improving growth and yield attributes, physio-biochemical attributes, and antioxidant defense systems in common bean plant grown under saline (NaCl) and/or cadmium (Cd2+) stress were assessed. Seed were sown in plastic pots filled with sand-free ions as a growing medium that watered with a ½-strength Hoagland's nutrient solution. Twenty five days after planting, pots were split into 4 plots; control (no stress), 150 mM NaCl (salt stress), 1.5 mM Cd2+ in CdCl2 (Cd2+ stress), and 100 mM NaCl + 1.0 mM Cd2+ (salt + Cd2+ stress). Four treatments; foliar spray with distilled water, 6 mM Si (in K2SiO3.nH2O) solution, 6 mM Pro solution, and a combination of Si and Pro were allotted under each of the 4 plots. The experimental layout was a completely randomized design with 15 replicates. Compared to control, NaCl or Cd2+ stress significantly (P ≤ 0.05) reduced plant growth and yield attributes, leaf contents of chlorophylls, carotenoids, N, P, and K+, K+/Na+ ratio, RWC, MSI, Pn and Tr, while elevated significantly leaf EL, leaf contents of proline, soluble sugar, glutathione, MDA, Na+, and root, leaf and pod contents of Cd2+. The activities of antioxidant enzymes were also raised. The combined stress (NaCl + Cd2+) was more influential. Addition of Si and/or Pro for common bean plants under NaCl and/or Cd2+ stress significantly enhanced all investigated attributes of physiology, morphology, and biochemistry, and further increased the activities of antioxidant enzymes. Supplementation of Si + Pro was the best treatment having more positive influential, especially reducing the Cd2+ content in Phaseolus vulgaris pods to the limits (0.27 mg kg-1) for legumes. Therefore, this combined treatment is recommended to use for alleviating environmental stress effects, especially salinity and Cd2+ for common bean production.