Aurasperone A Inhibits SARS CoV-2 In Vitro: An Integrated In Vitro and In Silico Study

Several natural products recovered from a marine-derived Aspergillus niger were tested for their inhibitory activity against SARS CoV-2 in vitro. Aurasperone A (3) was found to inhibit SARS CoV-2 efficiently (IC₅₀ = 12.25 µM) with comparable activity with the positive control remdesivir (IC₅₀ = 10.11 µM). Aurasperone A exerted minimal cytotoxicity on Vero E6 cells (CC₅₀ = 32.36 mM, SI = 2641.5) and it was found to be much safer than remdesivir (CC₅₀ = 415.22 µM, SI = 41.07). To putatively highlight its molecular target, aurasperone A was subjected to molecular docking against several key-viral protein targets followed by a series of molecular dynamics-based in silico experiments that suggested M^pro to be its primary viral protein target. More potent anti-SARS CoV-2 M^pro inhibitors can be developed according to our findings presented in the present investigation.     

Soil Salinization in Some Irrigated Areas of the Kingdom of Bahrain

Monitoring and assessment of agricultural land degradation is of vital importance for better land and water management planning and reclamation. It requires setting baseline information and basic analysis at specific time and space. About 33 geo-referenced soil sampling spots were selected in two agricultural production locations in the Kingdom of Bahrain to assess the status and preliminary causes of land degradation. Soil samples were taken from 13 sites in Diraz location while 19 samples were taken from Budayyi location. The samples were taken to 90 cm depth at 30 cm intervals. Standard procedures were followed to determine soil physiochemical properties. In addition, field observations on farm condition, distance from the sea, method of irrigation and irrigation water source were taken. Some of the soil samples were deliberately taken from outside the irrigated basins among trees compared with samples taken from inside the actively growing area for comparison. The results indicated that the salinity level was significantly （P 〈 0.001） higher at the 0-30 cm soil depth compared with 30-60 cm or 60-90 cm depths in both locations. The distance from the sea did not show clear correlation with surface soil salinity in Budayyi area compared with Diraz. Both locations showed significantly higher salinity levels on samples taken outside the actively growing areas compared with those taken from within. The effect is more prominent at the 0-30 cm depth. The observed variability on salinity levels may be attributed to farm management practices and deteriorating quality of ground water. Thus, agricultural land degradation in Bahrain cannot be attributed to ground water deterioration alone. The use of tertiary treated sewage water （TSE） may ease the pressure on ground water, but the pH of the TSE should be carefully monitored and managed with proper studies on leaching requirements to avoid further salinity complications.     

Anti-inflammatory activities of cucurbitacin E isolated from Citrullus lanatus var. citroides: role of reactive nitrogen species and cyclooxygenase enzyme inhibition

The in vivo and in vitro mechanistic anti-inflammatory actions of cucurbitacin E (CE) (Citrullus lanatus var. citroides) were examined. The results showed that LPS/INF-γ increased NO production in RAW264.7 macrophages, whereas L-NAME and CE curtailed it. CE did not reveal any cytotoxicity on RAW264.7 and WRL-68 cells. CE inhibited both COX enzymes with more selectivity toward COX-2. Intraperitoneal injection of CE significantly suppressed carrageenan-induced rat's paw edema. ORAC and FRAP assays showed that CE is not a potent ROS scavenger. It could be concluded that CE is potentially useful in treating inflammation through the inhibition of COX and RNS but not ROS.     

Soil organic carbon and phosphorus availability regulate abundance of culturable phosphate-solubilizing bacteria in paddy fields

Low availability of phosphorus(P) is a major constraint for optimal crop production, as P is mostly present in its insoluble form in soil. Therefore,phosphate-solubilizing bacteria(PSB) from paddy field soils of the Indo-Gangetic Plain, India were isolated, and their abundance was attempted to be correlated with the physicochemical characteristics of the soils. Ninety-four PSB were isolated on Pikovskaya's agar medium, and quantitative phosphate solubilization was evaluated using NBRIP medium. The isolates solubilized P up to a concentration of 1 006 μg mL~(-1) from tricalcium phosphate with the secretion of organic acids. These isolates were identified by 16 S rRNA gene sequence comparison, and they belonged to Gammaproteobacteria(56 isolates),Firmicutes(28 isolates), Actinobacteria(8 isolates), and Alphaproteobacteria(2 isolates). Phylogenetic analysis confirmed the identification by clustering the isolates in the clade of the respective reference organisms. The correlation analysis between PSB abundance and physicochemical characteristics revealed that the PSB population increased with increasing levels of soil organic carbon, insoluble P, K~+, and Mg~(2+). The promising PSB explored in this study can be further evaluated for their biofertilizer potential in the field and for their use as potent bio-inoculants.     

Extracts from Marine Macroalgae and Opuntia ficus-indica Cladodes Enhance Halotolerance and Enzymatic Potential of Diazotrophic Rhizobacteria and Their Impact on Wheat Germination Under Salt Stress

Soil salinity, which affects more than 6% of the earth’s land surface and more than 20% of its irrigated areas, is a major threat to agriculture. Diazotrophic bacteria are among the functional groups of soil microbiota that are threatened by this abiotic stress, as their activity is mostly inhibited by salt stress. Seventy bacterial strains with distinct characteristics were isolated from soils by using N-free Jensen’s selective medium. Based on their ability to produce metabolites of agricultural interest, four strains were selected and identified as Flavobacterium johnsoniae, Pseudomonas putida, Achromobacter xylosoxidans, and Azotobacter chroococcum. The selected strains were grown at different NaCl concentrations (0–600 mmol L~(-1) in N-free broth and 0–2 000 mmol L~(-1) in Luria-Bertani medium) in the presence and absence of glycine betaine (GB), aqueous and hydro-alcoholic extracts from marine macroalgae, Ulva lactuca and Enteromorpha intestinalis, and Opuntia ficus-indica cladodes. The selected bacterial strains, GB, and the aforementioned extracts were tested for their ability to promote the germination of wheat (Triticum durum) seeds at 0–300 mmol L~(-1) NaCl. Compared with the results obtained with the synthetic osmoprotectant GB, the extracts from O. ficus-indica, U. lactuca, and E. intestinalis significantly promoted bacterial growth and seed germination under salt stress.     

Effects of dietary marine microalgae,Tetraselmis suecica,on production,gene expression,protein markers and bacterial count of Pacific white shrimp Litopenaeus vannamei

The marine flagellated Chlorophyta Tetraselmis suecica is among the most important live food species in marine aquaculture. In the present study, the effects of dietary supplementation of dried marine microalgae, Tetraselmis suecica, on growth performance; feed utilization; chemical composition; gene expression of superoxide dismutase (SOD), glutathione peroxidase (GPx) and insulin‐like growth factor 2 (IGF‐II) gene of Pacific white shrimp, Litopenaeus vannamei; muscle protein polymorphism; and microbial count were assessed and evaluated. Three hundred and sixty L. vannamei (postlarvae) Pls (0.124 ± 0.002 g) were randomly stocked into 40‐L glass aquaria (30 shrimp/aquarium) and fed three times daily four tested diets: a basal diet (control), diet incorporated with 2.5 g kg^?1 dried T. suecica (T1), 5 g kg^?1 dried T. suecica (T2) and 7.5 g kg^?1 dried T. suecica (T3) in triplicates, for 90 days. At the end of the trial, the survival rate (SR) of L. vannamei fed diets supplemented with different levels of T. suecica was significantly (p < .05) higher than the control diet. The highest weight gain and specific growth rate and the best feed conversion ratio were recorded on L. vannamei fed a diet supplemented with a 7.5 g/kg dried T. suecica. The highest protein, lipid and ash contents were obtained in L. vannamei fed the diet containing 7.5 g/kg T. suecica, when compared with the remaining tested diets. The gene expression of antioxidant genes SOD and GPx was the lowest in the T3 group in comparison with the control group. Meanwhile, expression level of IGF‐II was higher in the T2 group. The total heterotrophic bacterial count was significantly (p < .05) increased with the cumulative T. suecica level, while no significant (p > .05) differences were found in the total Vibrio count among treatments. Overall, the present results have shown that the diet supplemented with the highest inclusion level of dried T. suecica resulted in improved growth and nutrient utilization.     

Population regulation of Galinsoga ciliata (Raf.) Blake and G. parviflora Cav.: Effect of 2,4-D application at different growth stages and light regimes

Population behaviour of two sympatric annual weeds, Galinsoga ciliata (Raf.) Blake and G. parviflora Cav., which occur abundantly in hill agro-ecosystems and secondary successional communities of north-east India, was studied in response to light intensity and 2,4-D application. Survival and growth of the two weeds were adversely affected by reduction in light intensity and increased concentration of 2,4-D. G. ciliata was more susceptible to 2,4-D, whereas G. parviflora to decrease in light. Leaf area ratio in G. ciliata increased under low light regime while that in G. parviflora decreased. The increased concentration of 2,4-D caused more severe effect on both weeds. The effect was, however, modified by the light intensity and age of plant at which the herbicide was applied. The application of 2,4-D at seedling stage under the high light regime caused greater mortality and growth reduction in both weeds, while the herbicide application at flowering stage resulted in much reduced production of viable seeds. Réglementation des peuplements de Galinsoga ciliata (Raf.) Blake et G. parviflora Cav.: Effet de l'application de 2,4-D à différents stades végétatifs et par des régimes lumineux variés Le comportement de peuplements de deux mauvaises herbes annuelles sympatriques, Galinsoga ciliata (Raf.) Blake et G. parviflora Cav., qui abondent dans les agro-écosystèmes de montagne ainsi que les communautés secondaires de succession dans le nord-est des Indes, a fait l'objet d'une étude par rapport à l'intensité lumineuse et aux applications de 2,4-D. Une luminosité moins intense, ainsi qu'une plus forte concentration de 2,4-D, a fait preuve d'une influence néfaste sur la croissance des deux adventices. G. ciliata s'est montré plus sensible envers le 2,4-D tandis que G. parviflora a réagi davantage à la diminution de lumière. Chez G. ciliata, la proportion de superficie foliaire a augmenté par un régime de faible luminosité tandis que chez G. parviflora elle a diminué. Une concentration plus importante de 2,4-D a augmenté l'effet néfaste chez les deux espèces. Cependant cet effet a subi des modifications selon la luminosité ainsi que l'âge de la plante au moment du traitement herbicide. Appliqué au stade plantule par une forte luminosité, le 2,4-D a provoqué chez les deux adventices une mortalité et une réduction de croissance plus marquées, tandis qu'une application à la fleuraison a amené une baisse considérable dans le nombre de graines viables. Populationsregulation von Galinsoga ciliata (Raf.) Blake und G. parviflora Cav.: Wirkung von 2,4-D Applikationen auf verschiedene Wachstums-stadien unter verschiedenen Lichtbedingungen Es wurde die Populationsdynamik zweier einjähriger, in denselben Arealen vorkommenden Unkräuter, Galinsoga ciliata (Raf.) Bale und G. parviflora Cav., häufig in Agro-Oekosystemen und sekundären Pflanzengesellschaften Nordost-Indiens vorhanden, in Bezug auf Einfluss von Licht und 2,4-D Applikation studiert. Das Ueberleben und das Wachstum der zwei Unkräuter wurde in gegensätzlicher Weise vonmay der Lichtintensität und steigender 2,4-D Konzentration beeinflusst. G. ciliata war empfindlicher auf 2,4-D; G. parviflora, jedoch, gegenüber starker Belichtung. Während die Blattfläche von G. ciliata bei schwachem Lichtangebot zunahm, nahm sie bei G. parviflora ab. An beiden Unkräutern verursachten steigende 2,4-D Konzentrationen eine zunehmende Wirkung. Dieser Effekt wurde allerdings durch Lichteinfluss und Alter der Pflanzen bei der Herbizidan-wendung beeinflusst. 2,4-D Applikation im Keimlingsstadium und unter hohem Lichtangebot verursachte eine höhere Mortalitätsrate und eine stärkere Wachstumsverringerung bei beiden Species, während die Herbizidbehandlung auf blühende Pflanzen eine stark verminderte Produktion lebensfähiger Samen zur Folge hatte.     

Population regulation of Galinsoga ciliata and G. parviflora

The population response of the two sympatric annual weeds, Galinsoga ciliata (Raf.) Blake and G. parviflora Cav., which occur abundantly in croplands and early secondary successional communities in the north-eastern hill region of India was studied in relation to sowing pattern (clump or scattered sowing), population density and soil moisture and texture. In a given sowing pattern, seed germination of both species declined with increase in sowing density and moisture stress. However, sowing of seeds in clumps and an increased proportion of sand in soil enhanced the germination, Fewer weeds died in the population raised from scattered sowing than from clumped distribution. Plants grown at high moisture level matured earlier, and fertility of the survivors was negatively correlated with both density and moisture stress in both species although G. ciliata was less affected. Seed output and dry matter yield per pot of both species increased with population density but the increase was not linearly related to the increase in plant numbers, and density-induced reduction in seed output was observed at high densities. Galinsoga ciliata appears to tolerate greater density-stress than G. parviflora. Asubstantial decrease in production of capitula, seeds and dry matter at low moisture level indicates the role played by soil moisture in regulating the population growth of the two weeds. An increased proportion of sand in soil resulted in significantly greater seed production in G. parviflora. Galinsoga ciliata also showed a similar trend although the differences were not statistically significant.