Optimal Immobilization of Acidic Proteases from Monterey Sardine (Sardinops sagax caeurelea) on Partially Deacetylated Chitin from Shrimp Head Waste

ABSTRACT

Response surface methodology was employed to optimize the immobilization yield of acidic proteases from Monterey sardine (Sardinops sagax caeurelea) using partially deacetylated chitin as immobilization support. A rotatable central composite design was applied to evaluate the effects of immobilization conditions such as enzyme loading (X₁), immobilization pH (X₂), and tripolyphosphate concentration (X₃) on the immobilization yield. The analysis of variance revealed that the established model was significant (p < 0.05), and the adjustment of the quadratic model with the experimental data was satisfactory. Under optimal conditions (X₁ = 0.05 mg/mL, X₂ = 3.16, and X₃ = 0.75%), an immobilization yield of 79.1% was achieved; a value that was in accordance with the predicted one.     

Cytotoxic Activity of Semi-Synthetic Derivatives of Elatol and Isoobtusol

In the present study, the in vitro cytotoxic effects of six semi-synthetic derivatives of elatol (1) and isoobtusol (2) were investigated. Chemical modifications were performed on the hydroxyl groups aiming to get derivatives of different polarity, namely the hemisuccinate, carbamate and sulfamate. The structural elucidation of the new derivatives was based on detailed NMR and MS spectroscopic analyses. The in vitro cytotoxicity of compounds 1 to 8 was evaluated against A459 and RD tumor cell lines with CC₅₀ values ranging from 4.93 to 41.53 µM. These results suggest that the structural modifications performed on both compounds could be considered a good strategy to obtain more active derivatives.     

Distance to flood meadows as a predictor of use of <Emphasis Type="Italic">Nothofagus pumilio</Emphasis> forest by livestock and resulting impact,in Patagonia,Argentina

Seedling browsing by livestock has been indicated as major threat for forest sustainability use. Nothofagus pumilio forests are part of the livestock raising system in Patagonia, but because of the sparse understory cover, livestock graze mainly on flood meadows within the forest matrix. The complexity of the environment under study (forests and flood meadows) means that an adaptive predictor is needed to evaluate the intensity of resource use by livestock in order to assess its effect on the forest. Distance to flood meadows was evaluated as a predictor of the use intensity of the forest by livestock and its effect on the understory. The study was conducted at three sites in Chubut Province, Patagonia–Argentina. We established transects in the forest 320 m long, starting at the edge flood meadow-forest. In these transects, the livestock presence indicators (soil compaction, density of feces and trails) and composition of the understory were evaluated. Generalized Linear Model for repeated measures for longitudinal data were used. The indicators showed that distance is efficient for estimating forest use intensity by livestock. The understory varied with distance, the cover of exotic herbaceous was higher near the flood meadow. Far from the flood meadow, the cover was entirely composited of native species. The results support the use of distance to flood meadows as a tool for decision making in livestock and forest management in N. pumilio forests, and for further research on livestock effect on the forest.     

Permeability and Retention to Water and Leachate of a Compacted Soil Used as Liner

In many developing countries, a landfill remains one of the most extensively employed solid waste disposal solutions. Although a landfill is a well-designed engineering system, the base lining of a landfill may perform poorly and allow the leachate to reach the underlying soil layers and groundwater. Leachates contain a variety of toxic and hazardous contaminants, which are attenuated in the soil by various processes that slow or transform them. Thus, the objective of this research was to study the water and leachate permeability and retention of the liner soil in a landfill experimental cell by subjecting it to geotechnical, chemical-mineralogical, and physicochemical characterizations, water and leachate permeability tests, and mercury intrusion porosimetry (MIP). In addition, the water and leachate retention curves were determined and analyzed using RETention Curve (RETC) software to obtain the unsaturated permeability curves. The leachate in the soil decreased the suction considering the moisture content of the compacted soil in the field, which consequently increased the leachate permeability of the mineral liner. For the same suction value, in the drying pathways, the soil retained a greater amount of distilled water than leachate. In the wetting pathways, the opposite occurred. Microorganisms were detected in the soil during the filter paper test. The permeability coefficients of the unsaturated soil were directly proportional to the gravimetric moisture content for the water and the leachate, which demonstrated that the soil presents lower unsaturated permeability coefficients for water than for leachate for the same water content.     

Distribution of the chemotypes ofWithania somnifera in some areas of Israel: Feeding studies withSpodoptera littoralis larvae and chemical examination of withanolide content

The geographical distribution of the chemotypes ofWithania somnifera Dun. (Solanaceae) in Israel was re-investigated. In the distribution area of chemotype II (major steroidal constituent, withanolide D), plants of chemotype III (major steroidal constituent, withanolide E) were also found. The antifeedant properties forSpodoptera littoralis larvae of leaves ofW. somnifera populations belonging to chemotype III are due to the presence of withanolide E and may be used, as a supplement to chemical analysis, to differentiate between chemotype III and other chemotypes ofW. somnifera.     

The ovicidal properties of the juvenile hormone mimic sumitomo S-31183 (SK-591) to insects

S-31183 was assayed against preimaginal stages of the tobacco whitefly,Bemisia tabaci (Genn.), and eggs of the Egyptian cotton leafworm,Spodoptera littoralis (Boisd.). The compound was found to be an ovicide forB. tabaci eggs in both preinfestation and postinfestation treatments. FreshS. littoralis eggs were very susceptible to the compound at 0.05 ppm a.i., response was much poorer with 1-2-day-old eggs and 2-3-day-old eggs were not affected even by 100 ppm. Publication of the Agricultural Research Organization. No. 2271-E, 1988 series.