Diterpenoids from Wedelia prostrata and Their Derivatives and Cytotoxic Activities

One new ent‐kaurane diterpenoid, 11β,16α‐dihydroxy‐ent‐kauran‐19‐oic acid ( 1 ), together with eight known analogues 2 – 9 were isolated from the aerial parts of Wedelia prostrata. One of the acidic diterpenoids, kaurenoic acid ( 3 ), was converted to seven derivatives, 10 – 16 . All compounds were evaluated for their cytotoxic activity in vitro against human leukemia (K562), liver (HepG‐2), and stomach (SGC‐7901) cancer cell lines. Only four kaurenoic acid derivatives, 13 – 16 , with 15‐keto and substitutions at C(19) position, exhibited notable cytotoxic activities on these tumor cell lines with IC₅₀ value ranging from 0.05 to 3.71 μm . Compounds 10 – 12 , with oxime on C(15) showed moderate inhibitory effects and compounds 1 – 9 showed no cytotoxicities on them. Structure–activity relationships were also discussed based on the experimental data obtained. The known derivative, 15‐oxokaurenoic acid 4‐piperdin‐1‐ylbutyl ester ( 17 ), induced typical apoptotic cell death in colon SW480 cells upon evaluation of the apoptosis‐inducing activity by flow‐cytometric analysis.     

Detection of antimicrobial substances from larvae of the black soldier fly,Hermetia illucens (Diptera: Stratiomyidae)

Maggots have become highly successful in the treatment of non‐healing wounds and multidrug‐resistant pathogen infections. The main objective of this study was to extract antibacterial substances from larvae of the black soldier fly, Hermetia illucens. To induce immune responses, we septically injured the larvae with a contaminated needle. Lyophilized H. illucens larvae were homogenized and extracted with acidic methanol. We examined the antifungal and antibacterial effects of the low molecular weight antimicrobial factors within the larval extract on the growth of a broad range of microorganisms, including Gram‐positive Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA), and Gram‐negative Pseudomonas aeruginosa. Furthermore, we isolated the anti‐MRSA substances from the larval extract using high performance liquid chromatography. These investigations revealed that the larval extract possessed a broad‐spectrum of antibacterial activity, demonstrating that secretions of H. illucens larvae prove useful in the fight against MRSA and can potentially be a source of novel antibiotic‐like compounds for infection control.     

Effects of Revegetation on Soil Microbial Biomass,Enzyme Activities,and Nutrient Cycling on the Loess Plateau in China

Revegetation is a traditional practice widely used for soil and water conservation on the Loess Plateau in China. However, there has been a lack of reports on soil microbial–biochemical indices required for a comprehensive evaluation of the success of revegetation systems. In this study, we examined the effects of revegetation on major soil nutrients and microbial–biochemical properties in an artificial alfalfa grassland, an enclosed natural grassland, and an artificial shrubland (Caragana korshinskii), with an abandoned cropland as control. Results showed that at 0–5, 5–20, and 20–40 cm depths, soil organic carbon, alkaline extractable nitrogen and available potassium were higher in natural grassland and artificial shrubland compared with artificial grassland and abandoned cropland. Soil microbial biomass C (Cmic) and phosphorous (Pmic) substantially decreased with depth at all sites, and in abandoned cropland was significantly lower than those of natural grassland, artificial grassland, and artificial shrubland at the depth of 0–5 cm. Soil microbial biomass N (Nmic) was higher in artificial shrubland and abandoned cropland compared with that in natural and artificial grasslands. Both Cmic and Pmic were significantly different between the 23‐year‐old and the 13‐year‐old artificial shrublands at the 0–5 cm depth. The activities of soil invertase, urease, and alkaline phosphatase in natural grassland and artificial shrubland were higher than those in artificial grassland and abandoned cropland. This study demonstrated that the regeneration of both natural grassland and artificial shrubland effectively preserved and enhanced soil microbial biomass and major nutrient cycling, thus is an ecologically beneficial practice for recovery of degraded soils on the Loess Plateau.     

Carbohydrate degradation and methane production during fermentation ofLaminaria saccharina (Laminariales,Phaeophyceae)

Anaerobic digestion of the brown algaLaminaria saccharina (L.) Lamour. harvested in spring and autumn was carried out at controlled laboratory conditions in stirred fermentor systems. Due to the normal seasonal variations, the autumn material had a much higher content of carbohydrates such as mannitol and laminaran. Both batch and semi-continuous feeding conditions were investigated for periods up to 800 h, with inoculum provided from previous kelp fermentations. In batch cultures, the methane yield from the autumn material was doubled compared to that of the spring material. Semi-continuous conditions gave more similar methane yields for both raw materials, 0.22 and 0.27 l CH₄ per g VS for spring and autumn material, respectively. In all experiments, mannitol and laminaran were reduced to less than 5 of the initial values within 24–48 hours after inoculation, whereas 30 of the alginate content was detectable even after 30 days. Viscometry revealed that this material was severely depolymerized, and alginate lyase activity was found to develop rapidly in all cultures. Although mannitol and laminaran were fermented much faster than alginate, the total accumulated methane yields seemed to be determined by the total carbohydrate content of the raw material during extended semi-continuous feeding.(*author for correspondence)     

The role of fecundity and sexual selection in the evolution of size and sexual size dimorphism in New World and Old World voles (Rodentia: Arvicolinae)

Evolutionary ecologists dating back to Darwin (1871) have sought to understand why males are larger than females in some species, and why females are the larger sex in others. Although the former is widespread in mammals, rodents and other small mammals usually exhibit low levels of sexual size dimorphism (SSD). Here, we investigate patterns of sexual dimorphism in 34 vole species belonging to the subfamily Arvicolinae in a phylogenetic comparative framework. We address the potential role of sexual selection and fecundity selection in creating sex differences in body size. No support was found for hyperallometric scaling of male body size to female body size. We observed a marginally significant relationship between SSD and the ratio of male to female home range size, with the latter being positively related to the level of intrasexual competition for mates. This suggests that sexual selection favours larger males. Interestingly, we also found that habitat type, but not mating system, constitutes a strong predictor of SSD. Species inhabiting open habitats – where males have extensive home ranges in order to gain access to as many females as possible – exhibit a higher mean dimorphism than species inhabiting closed habitats, where females show strong territoriality and an uniform distribution preventing males to adopt a territorial strategy for gaining copulations. Nonetheless, variation in the strength of sexual selection is not the only selective force shaping SSD in voles; we also found a positive association between female size and litter size across lineages. Assuming this relationship also exists within lineages (i.e. fecundity selection on female size), this suggests an additional role for variation in the strength of fecundity selection shaping interspecific differences in female size, and indirectly in SSD. Therefore our results suggest that different selective processes act on the sizes of males and females, but because larger size is favoured in both sexes, SSD is on average relatively small.     

Enzymatic Process Enhances the Flavour Profile and Increases the Proportion of Esters in Citrus Essential Oils

Citrus essential oils (CEOs) are important flavors in the food and confectionary industries. A lipase process was proposed for enhancing the flavor profiles and increasing the proportions of esters in CEOs. The effects of the enzymatic process were explored by detecting the constituents of the CEOs of American sweet orange oil (ASO) and Brazil mandarin oil (BMO) through GC/MS and sensory evaluation by a trained panel, and positive effects were confirmed by both methods. A further eleven kinds of CEOs were treated via the lipase process and increments of 10 – 1170% were achieved in the proportions of esters, which were mostly ethyl esters. Enhancement in fruity odor, especially the top note, was demonstrated by all CEOs after enzymatic processing. All CEOs were tested for antimicrobial activities, and only ASO displayed fairly ideal antimicrobial activities. Meanwhile, modified ASO showed a certain increase in antimicrobial activities. This methodology might be considered a sustainable route for acquiring ‘natural’ essential oils with enhanced flavor profiles and simultaneously enhancing the comprehensive utilization of citrus fruits.     

Ultrastructure of compatible and incompatible interactions in phloem sieve elements during the stylet penetration by cotton aphids in melon

Resistance of the melon line TGR‐1551 to the aphid Aphis gossypii is based on preventing aphids from ingesting phloem sap. In electrical penetration graphs (EPGs), this resistance has been characterized with A. gossypii showing unusually long phloem salivation periods (waveform E1) mostly followed by pathway activities (waveform C) or if followed by phloem ingestion (waveform E2), ingestion was not sustained for more than 10 min. Stylectomy with aphids on susceptible and resistant plants was performed during EPG recording while the stylet tips were phloem inserted. This was followed by dissection of the penetrated leaf section, plant tissue fixation, resin embedding, and ultrathin sectioning for transmission electron microscopic observation in order to study the resistance mechanism in the TGR. The most obvious aspect appeared to be the coagulation of phloem proteins inside the stylet canals and the punctured sieve elements. Stylets of 5 aphids per genotype were amputated during sieve element (SE) salivation (E1) and SE ingestion (E2). Cross‐sections of stylet bundles in susceptible melon plants showed that the contents of the stylet canals were totally clear and also, no coagulated phloem proteins occurred in their punctured sieve elements. In contrast, electron‐dense coagulations were found in both locations in the resistant plants. Due to calcium binding, aphid saliva has been hypothesized to play an essential role in preventing/suppressing such coagulations that cause occlusion of sieves plate and in the food canal of the aphid's stylets. Doubts about this role of E1 salivation are discussed on the basis of our results.     

Biological assessment of European lakes: ecological rationale and human impacts

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