Effects of cadmium and chlordane on cellular apoptosis in ecotoxicological test species

Cadmium and chlordane are compounds chosen for a preliminary study on the impact of environmental contaminants on apoptosis in different representative species. These two potentially toxic substances decrease in vitro apoptosis of Daphnia magna cells. This appears to be related to the chemical concentrations and the time exposure. Cadmium was also directly introduced to the cell culture medium of Syrian hamster embryos (SHE) or indirectly via daphnids, which had firstly consumed algae contaminated with cadmium. A very sharp transfer of cadmium toxicity from algae to daphnids is noted and an inhibition of the apoptosis in SHE cells can be observed.     

The metabolism of neonicotinoid insecticide thiamethoxam by soil enrichment cultures,and the bacterial diversity and plant growth‐promoting properties of the cultured isolates

A soil enrichment culture (SEC) rapidly degraded 96% of 200 mg L^?1 neonicotinoid insecticide thiamethoxam (TMX) in MSM broth within 30 d; therefore, its metabolic pathway of TMX, bacterial diversity and plant growth‐promoting rhizobacteria (PGPR) activities of the cultured isolates were studied. The SEC transformed TMX via the nitro reduction pathway to form nitrso, urea metabolites and via cleavage of the oxadiazine cycle to form a new metabolite, hydroxyl CLO‐tri. In addition, 16S rRNA gene‐denaturing gradient gel electrophoresis analysis revealed that uncultured rhizobacteria are predominant in the SEC broth and that 77.8% of the identified bacteria belonged to uncultured bacteria. A total of 31 cultured bacterial strains including six genera (Achromobacter, Agromyces, Ensifer, Mesorhizobium, Microbacterium and Pseudoxanthomonas) were isolated from the SEC broth. The 12 strains of Ensifer adhaerens have the ability to degrade TMX. All six selected bacteria showed PGPR activities. E. adhaerens TMX‐23 and Agromyces mediolanus TMX‐25 produced indole‐3‐acetic acid, whereas E. adhaerens TMX‐23 and Mesorhizobium alhagi TMX‐36 are N₂‐fixing bacteria. The six‐isolated microbes were tolerant to 200 mg L^?1 TMX, and the growth of E. adhaerens was significantly enhanced by TMX, whereas that of Achromobacter sp. TMX‐5 and Microbacterium sp.TMX‐6 were enhanced slightly. The present study will help to explain the fate of TMX in the environment and its microbial degradation mechanism, as well as to facilitate future investigations of the mechanism through which TMX enhances plant vigor.     

Degradation and acute toxicity of Methidathion and Trichlorfon on Procambarus clarkii,in experimental conditions

Routine applications of organophosphate pesticides may adversely affect many nontarget organisms. Static toxicities in mature crayfish Procambarus clarkii were determined, in laboratory, for two organophosphate insecticides using 24, 48, 72 and 96‐h static tests. Three groups of 10 crayfish were exposed to 0.75 to 6 ppm for Trichlorfon and 0.2 to 0.9 ppm for Methidathion. The 24 to 96‐h LC50 values for Trichlorfon and Methidathion were from 5.14–0.99 ppm and 0.73–0.28 ppm respectively. Studies of degradation of Methidathion and Trichlorfon have been made using 1 ppm for Methidathion and 0.1 ppm for Trichlorfon. Both insecticides were degradated gradually until 96‐h. Results show that Methidathion is more toxic to P. clarkii in our medium and degradation of both pesticides is similar.     

When does benevolent leadership lead to creativity? The moderating role of creative role identity and job autonomy

The present study identified creative role identity and job autonomy as two moderators that influence the relationship between benevolent leadership, a leadership style that prevails in paternalistic contexts, and creativity. Using 167 dyads of supervisor and subordinate as a sample, we found that both creative role identity and job autonomy have significant moderating effects: When each moderator is high, the positive relationship between benevolent leadership and creativity is stronger; when each moderator is low, this relationship is weaker. Our results suggest that the effect of benevolent leadership upon creativity is dependent on the coexistence of important individual and contextual factors. Copyright © 2009 John Wiley & Sons, Ltd.     

On the Relationship Between Mean and Variance of Soil Moisture Fields1

Abstract: The objective of this work was to explain an apparent contradiction in the literature related to the relationship between mean and variance (or standard deviation) of soil moisture fields. Some studies found an increase in soil moisture variance with decreasing mean soil moisture, while others showed a decrease. The evidence of maximum variance in the mid‐range of mean soil moisture was also reported in the literature. In this paper, we focus on the effects of spatial variability of soil texture on the relationship between variance and mean of soil moisture during soil dry‐down processes. Soil texture influences soil moisture mean and variance through its direct effects on evaporation and drainage, which are two main factors controlling soil drying. A differential equation describing soil moisture dry down is proposed and studied. Our study shows that as mean soil moisture is greater than a threshold, variance increases with decreasing mean soil moisture. If mean soil moisture is less than the threshold, variance decreases with decreasing mean soil moisture. The threshold depends on soil texture and is between the field capacity and the wilting point. The soil moisture dry‐down equation is also applied to explain the apparent contradiction with regard to the relationship between mean and variance of soil moisture fields reported in the literature.     

Predicting Recovery Criteria for Threatened and Endangered Plant Species on the Basis of Past Abundances and Biological Traits

Recovery plans for species listed under the U.S. Endangered Species Act are required to specify measurable criteria that can be used to determine when the species can be delisted. For the 642 listed endangered and threatened plant species that have recovery plans, we applied recursive partitioning methods to test whether the number of individuals or populations required for delisting can be predicted on the basis of distributional and biological traits, previous abundance at multiple time steps, or a combination of traits and previous abundances. We also tested listing status (threatened or endangered) and the year the recovery plan was written as predictors of recovery criteria. We analyzed separately recovery criteria that were stated as number of populations and as number of individuals (population‐based and individual‐based criteria, respectively). Previous abundances alone were relatively good predictors of population‐based recovery criteria. Fewer populations, but a greater proportion of historically known populations, were required to delist species that had few populations at listing compared with species that had more populations at listing. Previous abundances were also good predictors of individual‐based delisting criteria when models included both abundances and traits. The physiographic division in which the species occur was also a good predictor of individual‐based criteria. Our results suggest managers are relying on previous abundances and patterns of decline as guidelines for setting recovery criteria. This may be justifiable in that previous abundances inform managers of the effects of both intrinsic traits and extrinsic threats that interact and determine extinction risk. Predicción de Criterios de Recuperación para Especies de Plantas en Peligro y Amenazadas con Base en Abundancias Pasadas y Atributos Biológicos     

Actual and Potential Use of Population Viability Analyses in Recovery of Plant Species Listed under the U.S. Endangered Species Act

Use of population viability analyses (PVAs) in endangered species recovery planning has been met with both support and criticism. Previous reviews promote use of PVA for setting scientifically based, measurable, and objective recovery criteria and recommend improvements to increase the framework's utility. However, others have questioned the value of PVA models for setting recovery criteria and assert that PVAs are more appropriate for understanding relative trade‐offs between alternative management actions. We reviewed 258 final recovery plans for 642 plants listed under the U.S. Endangered Species Act to determine the number of plans that used or recommended PVA in recovery planning. We also reviewed 223 publications that describe plant PVAs to assess how these models were designed and whether those designs reflected previous recommendations for improvement of PVAs. Twenty‐four percent of listed species had recovery plans that used or recommended PVA. In publications, the typical model was a matrix population model parameterized with ≤5 years of demographic data that did not consider stochasticity, genetics, density dependence, seed banks, vegetative reproduction, dormancy, threats, or management strategies. Population growth rates for different populations of the same species or for the same population at different points in time were often statistically different or varied by >10%. Therefore, PVAs parameterized with underlying vital rates that vary to this degree may not accurately predict recovery objectives across a species’ entire distribution or over longer time scales. We assert that PVA, although an important tool as part of an adaptive‐management program, can help to determine quantitative recovery criteria only if more long‐term data sets that capture spatiotemporal variability in vital rates become available. Lacking this, there is a strong need for viable and comprehensive methods for determining quantitative, science‐based recovery criteria for endangered species with minimal data availability. Uso Actual y Potencial del Análisis de Viabilidad Poblacional para la Recuperación de Especies de Plantas Enlistadas en el Acta de Especies En Peligro de E.U.A     

Rapid liquid chromatographic analysis of flurazepam in pharmaceutical preparation

An accurate and reproducible method for the analysis of flurazepam hydrochloride in pharmaceutical preparations has been described. A simple and rapid isocratic HPLC elution method was employed which requires about 15 minutes to be performed. The percentage mean recovery of flurazepam hydrochloride in Dalmane capsules was found to be 100.67% + 1.23% of the declared amount     

Adsorption and removal of antimony from aqueous solution by an activated Alumina

The adsorption of Sb(V) ions from aqueous solutions onto commercially available activated alumina (AA) was investigated. AA has a much higher adsorption capacity than presently used adsorbents. Sb(V) ions are likely adsorbed through electrostatic attraction and/or specific adsorption mechanism, while the optimum pH is found in the range of 2.8–4.3. The Sb(V) ions adsorption capacities increase with increasing temperature. The addition of nitrate, acetate, arsenite, chloride, and silicate ions affected Sb(V) ions adsorption only slightly, while the coexisting ascorbate, arsenate, phosphate, sulfate, EDTA, tartrate, and citrate ions substantially depressed Sb(V) ions adsorption.     

Task knowledge overlap and knowledge variety: the role of advice network structures and impact on group effectiveness

Drawing from the structural perspective of social capital theory, this research investigates how internal and external advice network structures influence knowledge overlap and variety and, how these knowledge dimensions in turn influence group effectiveness. Findings from two studies on knowledge‐intensive groups indicate that different advice network structures are associated with knowledge overlap and knowledge variety, and only knowledge variety was significantly associated with group effectiveness. In addition, despite implicit understanding that advice networks aid performance through enhancing knowledge outcomes, only knowledge variety was found to mediate the relationship between external network and group effectiveness. Implications for theory and practice are discussed. Copyright © 2007 John Wiley & Sons, Ltd.