Organic Carbon and Alkalinity Increase in Topsoil After Rangeland Restoration Through Atriplex nummularia Plantation

This research studied the impact of fodder shrub plantations (Atriplex nummularia Lindl.) on topsoil properties, with particular reference to organic carbon, nitrogen, and soluble salts, in the Marrakech region (central Morocco). The studied plantation interventions were carried out to rehabilitate degraded rangeland and to mitigate desertification. The field experiment was conducted by drawing seventeen 50‐m‐long transects designed according to the ecological patch–interpatch approach defined by the Landscape Function Analysis. The top soil (0–5 cm) was sampled in 134 microsites, covering the main patch and interpatch types in plantation and control plots. The following variables were determined: pH, carbonates, organic carbon, total nitrogen, electrical conductivity, and soluble ions (Na⁺, K⁺, Ca²⁺, Mg²⁺ Cl⁻, NO₃⁻, SO₄²⁻ and PO₄³⁻). Statistical analyses were carried out to analyse changes between sites and between patch types. Most of the studied properties were strongly affected by the spatial pattern defined by the plantation, particularly when the sites with higher biomass production were considered. Organic carbon increased by around 63% and 117% when the under canopy patches were compared, respectively, to the between‐plants interpatches and to the control plots, a strong positive effect considering the aridity of the study area. On the other hand, a stronger increase was detected under canopy for most soluble salts and sodium adsorption rate. On average, the latter increased by 350% and up to 450% under the best developed plants, a stronger impact than observed in previous research, highlighting the very strong plant effect on the soil surface alkalinity. Copyright © 2015 John Wiley & Sons, Ltd.     

Large‐scale Modeling of Soil Erosion with RUSLE for Conservationist Planning of Degraded Cultivated Brazilian Pastures

Pasture degradation is one of the major environmental and economic problems of Brazilian livestock production. Based on the estimates of soil loss in 140,297 km² pasturelands of Goiás State and the Federal District, the effects of land use and management and conservation practices on soil erosion by water were evaluated. Soil loss was estimated with the empirical revised universal soil loss equation model under four scenarios of land use and management of pastures and the implementation of terraces. The effects of converting hilly areas into permanently preserved areas were also evaluated. Well‐managed pastures planted in terraces and highly sloped areas with native vegetation featured a reduction of 709% in the rate of soil erosion by water in comparison with poorly managed pastures without soil conservation practices. The environmental consequences of pasture degradation become particularly important when they are associated with land use in the Amazon and Cerrado biomes because farmers in these regions are forced to open new natural areas. In addition, the high indices of bare soil in degraded pastures contribute significantly to sediment deposition in rivers and dams. The modeling of soil loss is demonstrated to be an important tool for land use planning and supporting public policies focused on the sustainable use of natural resources. The results of these simulations demonstrate the importance of actions to recover degraded pastures, such as the Federal Government's program known as ABC (Low Carbon Agriculture). Copyright © 2015 John Wiley & Sons, Ltd.     

Insect communities related to wheat and coriander cropping histories and essential oils in the Rolling Pampa, Argentina

Intensive land use in the Rolling Pampa of Argentina have resulted in a mosaic of fields with different cultural histories creating different soil environments, which interact with crops and cropping activities producing a wide range of habitats for insects. Species and functions in canopy structure, food quality and essential oils of the crop–weed associations may vary depending on the field's cropping history and management (i.e. crops, soil degradation, weeding and fertilization). Species composition and functional structure of insect communities may respond to these changes. We studied insect communities in wheat and coriander crops that differed in their canopy structures, essential oil production, and the cropping histories of the fields on which they grew. For this purpose we planted wheat (Triticum aestivum L.), and two coriander (Coriandrum sativum L.) landraces in plots with two levels of weeding and fertilization. The crops were grown in two consecutive years at two locations differing in cropping history and related to this in level of soil degradation. Insects were sampled in all plots at crop full flowering, and were classified and related to agronomic variables and to essential oils using multivariate techniques. Among all the environmental factors tested in this study, year and soil degradation were the main factors explaining insect community structure; and also weed community structure in unweeded plots. The proportion of essential oil components varied with cropping history, suggesting an association among soil properties indicative of soil degradation, plant chemical signals and insect distribution. Although insect community composition varied widely, functional structure was very similar among crop–weed communities. Soil degradation appeared to have affected directly crop–weed communities and insects’ assemblages, since no consistent relationship was found between plant composition and insect community structure. It can be hypothesized that soil degradation might have affected the amount of volatiles produced especially by coriander, generating a “soil degradation scent” that determined the structure in the insect community, and/or the soil itself emitted different signals, in relation to changes in its physical, chemical and biological characteristics.     

Phenolic compounds in seven South American Ilex species.

Ilex paraguariensis (common name: 'mate' or 'yerba mate') is used for the preparation of the most popular tea-like beverage of South America. Choleretic, hypocholesteremic, antioxidant, hepatoprotective and bitter taste properties of mate are attributed to the phenolic constituents of the leaves. I. paraguariensis has seven local congeneric substitutes or adulterants: I. brevicuspis; I. theezans; I. microdonta; I. dumosa var. dumosa; I. taubertiana; I. pseudobuxus; I. integerrima; and I. argentina. An HPLC method using UV with Photodiode Array Detector was developed for the identification and quantification of caffeoyl derivatives (caffeic acid, chlorogenic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid) and flavonoids (quercetin, rutin and kaempferol) in these species. I. paraguariensis showed a higher content of flavonoids and caffeoyl derivatives than the other assayed species.     

Long‐lasting Effect Against White Spot Syndrome Virus in Shrimp Broodstock,Litopenaeus vannamei,by LvRab7 Silencing

The white spot syndrome virus (WSSV) remains the most devastating viral pathogen of shrimp culture worldwide. Gene silencing by RNA interference (RNAi) using double stranded RNA (dsRNA) has been considered a powerful tool for conferring protection against WSSV when viral genes are silenced, as documented in several shrimp species. However, this effect is not long lasting. Our results provide the first evidence that long‐term silencing of the LvRab7 endogen produced antiviral effect against WSSV, which endured at least 21 d after dsRNA treatment (dat). Until now, the most efficient way to implement RNAi with dsRNA into the shrimp is by injection. Consequently, its application to broodstock in hatcheries is possible, minimizing the risk of vertical transmission of the virus. We show that the expression of Rab7 in hemocytes is lowest at 2 dat and finally recovers to basal status. In contrast, in gills and pleopods, gene expression silencing continued for at least 21 d. We challenged Litopenaeus vannamei broodstock with WSSV at 7, 14, or 21 dat reaching mortality rates of 0, 40, and 27%, respectively. In conclusion, the LvRab7 gene silencing is progressive and effective against WSSV. However, further studies are necessary to elucidate the functions of Rab7 in shrimp cells before applying this methodology at a commercial level.     

Activity and stability of jack bean urease in the presence of peat humic acids obtained using different extractants

 The effects of two humic acid extractants, 0.1 M Na₄P₂O₇ plus 0.1 M NaOH (NaPP) and 0.1 M NaOH (NaOH), on the activity and stability of a humic-urease complex were studied. The two humic acids isolated (HA_NaPP and HA_NaOH) exhibited different elemental compositions, metal concentrations and structural modifications in the FT-IR spectra. Depending on the pH, HA_NaPP and HA_NaOH influenced both the urease activity and urease kinetic parameters (V _max and K _m) in the same way. They inhibited urease activity between pH 6 and 7 and reduced the V _max of the reaction at pH 6 and 7. The presence of humic acids improved the affinity of the enzyme for the substrate (K _m). The stability of the urease with time, and in the presence of pronase, was improved by HA_NaPP and HA_NaOH with respect to free enzyme. These results confirm the importance of the interaction of urease with humic acids as a fundamental gateway for extracellular urease stabilisation. Since no difference in the extent of urease inhibition and urease stabilisation was observed for the two humic acids, it may be concluded that neither urease activity nor stability are influenced by the humic acid extractant used. Received: 5 November 1999     

Cryopreservation of Trypanosoma evansi after DEAE-cellulose purification: Evaluation of infective parameters

Cryopreservation is a method of keeping parasites alive in a laboratory. However, this technique may also damage the parasite. Alternatively, parasites may be maintained by in vitro culture. Unfortunately, for Trypanosoma evansi no effective medium that is able to maintain the parasite for more than 4 months has been described. In this study, we examined the effect of purifying trypomastigote through DEAE-cellulose chromatography before and after cryopreservation, by analyzing the pre-patent period, longevity, parasitemia, and count of viable parasites. Our results showed a three-times increase in the concentration of viable trypomastigote in DEAE-purified cryopreserved parasites as compared to non-DEAE-purified cryopreserved parasites. This indicates that DEAE-cellulose chromatography followed by cryopreservation is an effective method for the storage and preservation of T. evansi, with the advantage that the stocked parasites will be ready to use in molecular biology procedures.     

Land restoration by fodder shrubs in a semi-arid agro-pastoral area of Morocco. Effects on soils

The present study assesses the effects of Atriplex nummularia Lindl. growth on soil chemical properties in a semi-arid area. The area is located in the Marrakech province (Morocco), in a degraded agropastoral region subjected to soil restoration actions based on fodder shrub plantations.     

Extracts of Maqui ( Aristotelia chilensis ) and Murta ( Ugni molinae Turcz.): sources of antioxidant compounds and α-Glucosidase/α-Amylase inhibitors

The objective of this work was to evaluate the antioxidant and antihemolytic activities of crude, aqueous, and organic-aqueous extracts of maqui ( Aristotelia chilensis ) and murta ( Ugni molinae Turcz.), together with their inhibiting effect on enzymes involved in the metabolism of carbohydrates. Radical scavenging activity, inhibition of linoleic acid oxidation in a micellar system, antihemolytic activity, and inhibition of α-amylases and α-glucosidases were analyzed. Crude extracts of maqui leaves and fruits were found to be important sources of polyphenolic compounds, showing 69.0 ± 0.9 and 45.7 ± 1.1 mg GAE/g dm, respectively. Polyphenols from maqui leaves were active as antioxidants and antihemolytic compounds (p < 0.05), showing a noncompetitive inhibiting effect on α-glucosidase. Flavan-3-ol polymers and glycosylated flavonols, such as quercetin glucoside and kaempferol glucoside, were tentatively identified in extracts. This preliminary observation provides the basis for further examination of the suitability of polyphenol-enriched extracts from maqui and murta as nutritional or medicinal supplements with potential human health benefits.     

Profiling of resveratrol oligomers, important stress metabolites, accumulating in the leaves of hybrid Vitis vinifera (Merzling × Teroldego) genotypes infected with Plasmopara viticola

In the Vitaceae, viniferins represent a relatively restricted group of trans-resveratrol oligomers with antifungal properties, thus enabling plants to cope with pathogen attack. The aim of this study was to perform isolation and structural characterization of the whole class of viniferins accumulating in the leaves of hybrid Vitis vinifera (Merzling × Teroldego) genotypes infected with Plasmopara viticola . Infected leaves of resistant plants were collected 6 days after infection, extracted with methanol, and prepurified by flash chromatography using ENV+ and Toyopearl HW 40S resins. Further fractionation using normal-phase preparative chromatography and then reversed-phase preparative chromatography allowed isolation of 14 peaks. The isolated compounds were identified using advanced mass spectrometry techniques and extensive one- and two-dimensional nuclear magnetic resonance measurements, UV, CD, optical properties, and molecular mechanic calculations. The results demonstrated the presence in infected leaves of seven dimers (six stilbenes and one stilbenoid), of which four were new in grapevine (ampelopsin D, quadrangularin A, E-ω-viniferin, and Z-ω-viniferin), four trimers (three stilbenes and one stilbenoid), of which two (Z-miyabenol C and E-cis-miyabenol C) were new in grapevine, three tetramer stilbenoids, all new in grapevine, isohopeaphenol, ampelopsin H, and a vaticanol C-like isomer. The isolation of a dimer deriving from the condensation of (+)-catechin with trans-caffeic acid also indicated that other preformed phenolics are structurally modified in tissues infected with P. viticola.