Comparison of basal cytotoxicity of seven carbamates in CHO-K1 cells

The cytotoxic effects of seven carbamate pesticides, aldicarb, aldicarb sulfone, aldicarb sulfoxide, benfuracarb, pirimicarb, propoxur and thiobencarb, were compared in Chinese hamster ovary (CHO-K1) cell line of Circetulus griseus. The endpoints evaluated were lysosomal function by neutral red assay and mitochondrial integrity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT assay). The carbamates tested were evaluated in both serum-free medium and in serum-containing medium. Results demonstrate that CHO-K1 lysosomes appeared more susceptible to propoxur, aldicarb and its metabolites than mitochondria. Aldicarb was the most toxic carbamate pesticide tested on CHO-K1 cells and aldicarb sulfoxide the least. The presence of foetal calf serum (FCS) diminished significantly the cytotoxicity of tested carbamates.     

In vitro effects of lead on fatty acid composition,oxidative stress biomarkers and quality of ram spermatozoa

The sperm quality and several parameters associated with oxidative stress were evaluated in ram (Ovis aries) spermatozoa suspensions incubated with 0, 50 or 500 ng/mL Pb during 0, 1, 3 or 6 h. The presence of Pb during incubation, reduced the integrity of the acrosome, % sperm motility and integrity, and the functionality of membrane. On the contrary, % polyunsaturated fatty acids and the activities of glutathione peroxidase and superoxide dismutase in the spermatozoa suspensions were not affected by Pb. Moreover, glutathione peroxidase activity was decreased and the fatty acid composition changed due to the relative increase in % stearic acid during the incubation time independently on Pb presence. Data showed that several effects of Pb on sperm quality usually observed in vivo also occurred in vitro, but without any relationship with oxidative stress biomarkers.     

Effects of polyaluminium chloride on the freshwater invertebrate Daphnia magna

In a number of countries across the world, aluminium in the form of polyaluminium chloride has been used in the treatment of freshwaters for the direct removal of cyanobacteria, or phosphorus removal, but knowledge about its effect on zooplankton species is poor. In our study, polyaluminium chloride toxicity was tested on both artificial and natural freshwaters for a better understanding and prediction of effects in real ecosystems. Our results indicate that prediction of effects in a real ecosystem based on standard ISO methods is insufficient, and tests with nontarget species (including invertebrates) should be done before each treatment using the water samples from the treated location. Effective concentrations of polyaluminium chloride can differ markedly according to the type of water composition used in the assay. Our experiments proved that EC₅₀ values can fluctuate between 9.89 and 54.29 mg·L^?1 of Al³⁺, and the toxicity is dominantly dependent on the treated water conductivity. This parameter seems to be the dominant source of different effects on zooplankton species after treatment and thus should be properly tested before each use of polyaluminium chloride as a treatment compound.     

Effects of sampling completeness on the structure of plant-pollinator networks

Plant-animal interaction networks provide important information on community organization. One of the most critical assumptions of network analysis is that the observed interaction patterns constitute an adequate sample of the set of interactions present in plant-animal communities. In spite of its importance, few studies have evaluated this assumption, and in consequence, there is no consensus on the sensitivity of network metrics to sampling methodological shortcomings. In this study we examined how variation in sampling completeness influences the estimation of six network metrics frequently used in the literature (connectance, nestedness, modularity, robustness to species loss, path length, and centralization). We analyzed data of 186 flowering plants and 336 pollinator species in 10 networks from a forest-fragmented system in central Chile. Using species-based accumulation curves, we estimated the deviation of network metrics in undersampled communities with respect to exhaustively sampled communities and the effect of network size and sampling evenness on network metrics. Our results indicate that: (1) most metrics were affected by sampling completeness but differed in their sensitivity to sampling effort; (2) nestedness, modularity, and robustness to species loss were less influenced by insufficient sampling than connectance, path length, and centralization; (3) robustness was mildly influenced by sampling evenness. These results caution studies that summarize information from databases with high, or unknown, heterogeneity in sampling effort per species and should stimulate researchers to report sampling intensity to standardize its effects in the search for broad patterns in plant-pollinator networks.     

Contrasting approved uses against actual uses at La Restinga Lagoon National Park, Margarita Island, Venezuela. A GPS and GIS method to improve management plans and rangers coverage

Protected areas are the core of efforts to conserve biological diversity and zoning uses, and they are used as a tool for their management. Global Positioning Systems (GPS) and Geographic Information System (GIS) have been used to evaluate conflicts between approved uses and actual uses in La Restinga Lagoon National Park in Venezuela (LRLNP). The park (188.6 km²), covers various ecosystems such as coastal lagoons, marine waters and xerophytic vegetation, it is visited by up to 260,000 people visit per year. A GIS, using a base map compiled from 1:25,000 maps was developed. Natural cover was mapped from LANDSAT VII TM images, orthophotomaps and aerial photographs. Spatial use data was collected by field GPS location of any use inside the park during 2 years. Thematic vector maps for each land cover, zoning area, and observed use were created. Maps of zoning and uses were overlapped and new maps for each use-zoning crossing were created. The park contain nine different zoning areas wherein 28 different uses were identified, 18 of them were direct consumptive and non-consumptive uses, occurring on 54% of the park. Tourism transit areas were the most used zones. More than 5,000 people use the park during a high season day. Superimposition of zoning maps with actual use data produced 13 uses taking place in not allowed areas (46% of park area). Most common prohibited use was commercial net fishing, occurring in nearly 40% of the park area. Therefore, identifying human use conflicts and its geographical distribution is a key issue to improve Management Plans as well as identifying hot sites. The GPS-GIS methodology presented here allows Park Rangers to select those areas which could benefit from enhanced supervision with the limited budget available.     

Aerobic oxidation of secondary benzyl alcohols catalyzed by phosphinite-based palladium pincer complexes

Environmental Chemistry Letters - Aerobic oxidation of organic compounds is receiving attention because molecular oxygen is an abundant, cheap and comparatively safe reagent. Several catalyst...     

Role of plant enemies in the forestry of indigenous vs. nonindigenous pines

Plantations of rapidly growing trees are becoming increasingly common because the high productivity can enhance local economies, support improvements in educational systems, and generally improve the quality of life in rural communities. Landowners frequently choose to plant nonindigenous species; one rationalization has been that silvicultural productivity is enhanced when trees are separated from their native herbivores and pathogens. The expectation of enemy reduction in nonindigenous species has theoretical and empirical support from studies of the enemy release hypothesis (ERH) in the context of invasion ecology, but its relevance to forestry has not been evaluated. We evaluated ERH in the productive forests of Galicia, Spain, where there has been a profusion of pine plantations, some with the indigenous Pinus pinaster, but increasingly with the nonindigenous P. radiata. Here, one of the most important pests of pines is the indigenous bark beetle, Tomicus piniperda. In support of ERH, attacks by T. piniperda were more than twice as great in stands of P. pinaster compared to P. radiata. This differential held across a range of tree ages and beetle abundance. However, this extension of ERH to forestry failed in the broader sense because beetle attacks, although fewer on P. radiata, reduced productivity of P. radiata more than that of P. pinaster (probably because more photosynthetic tissue is lost per beetle attack in P. radiata). Productivity of the nonindigenous pine was further reduced by the pathogen, Sphaeropsis sapinea, which infected up to 28% of P. radiata but was absent in P. pinaster. This was consistent with the forestry axiom (antithetical to ERH) that trees planted "off-site" are more susceptible to pathogens. Fungal infections were positively correlated with beetle attacks; apparently T. piniperda facilitates S. sapinea infections by creating wounds and by carrying fungal propagules. A globally important component in the diminution of indigenous flora has been the deliberate large-scale propagation of nonnative trees for silviculture. At least for Pinus forestry in Spain, reduced losses to pests did not rationalize the planting of nonindigenous trees. There would be value in further exploration of relations between invasion ecology and the forestry of nonindigenous trees.     

Effects of Management on Understory Diversity in the Forest Ecosystems of Northern Spain

Pine plantations are an alternative to marginal agriculture in many countries, and are often presented as an option that improves biodiversity. However, these plantations can have adverse environmental effects if improperly managed. To evaluate the effect of forest management practices on biodiversity, the diversity, species richness, dominance and frequency of understory woody plant species in different forests of the Basque Country (northern Spain) were compared. Plantations of exotic conifers (Pinus radiata [D.] Don) of different ages were compared with deciduous forests of Quercus robur L. and Fagus sylvatica L. The effects of different types and intensities of management were taken into account. The differences observed were mainly conditioned by the intensity of forestry management, although the response varied according to forest type and age. In unmanaged pine plantations, the diversity and species richness of the understory increased rapidly after planting (while dominance decreased), remained stable in the intermediate age range, and reached a maximum in plantations more than 25 years of age. Management practices resulted in decreased understory diversity and species richness, as well as greater dominance. This was more pronounced in younger than in older stands. Moderate management, however, favored a greater diversity of the understory in deciduous forests. The species composition of the plantations and deciduous forests were different, the latter having a wider range of characteristic species. Knowledge of how forestry practices influence biodiversity (in terms of diversity, richness, dominance, and species composition) may allow predictions to be made about the diversity achievable with different management systems.