Penetration studies of propoxur and phoxim from eggshell into whole egg after experimental exposure and application in henhouses

The penetration of propoxur and phoxim from eggshell into whole egg was investigated in vitro by spraying eggs directly and in vivo after application of the compounds in henhouses. Although mean concentrations of the compounds on eggshells were up to 23000 microg kg(-1), mean residue concentrations in whole eggs were far below the current maximum residue levels (50 microg kg(-1) for propoxur and 60 microg kg(-1) for phoxim). These results provide the first evidence that propoxur and phoxim do not penetrate from eggshell into whole egg under experimental and field conditions. Subsequently, residue carry-over after egg cracking in households and during a worst-case situation in an egg-cracking plant was investigated. However, when eggs were cracked manually, a negligible contamination of whole egg values occurred. If, in an automated process, eggshells accidentally come into close contact with whole egg, very high residue levels of propoxur and phoxim may be generated time dependently. These results suggest that eggshell contact with whole egg during egg cracking must be avoided to prevent pesticide carry-over.     

How do the green components of urban green infrastructure influence the use of ecosystem services? Examples from Leipzig,Germany

Landscape Ecology - The pressure on remaining open spaces of urban green infrastructure (UGI) is high due to increasing urbanization and the multiple requirements of a diverse urban population....     

Nutrient flows and balances at the field and farm scale: Exploring effects of land-use strategies and access to resources

Nutrient flux and balance studies are valuable tools to assess the sustainability of agro-ecosystems and potential consequences for agricultural productivity. This paper presents results from a study at the field/farm scale representing mixed farming systems typical for the East African Highlands. We selected catchments in the Dega (cool highlands and Woina Dega (warm-to-cool mid-highlands) of the Central Highlands of Ethiopia, to get more insight on how individual land use strategies and access to resources affect the magnitude of nutrient flows and resulting balances and to explore some of reasons of the variability within and between farming systems at different altitudes. Our results show that environmental condition, farming system (e.g. choice of crop), access to resources (e.g. land, livestock and fertilizer) and smallholders’ source of off farm income influence the magnitude of nutrient fluxes and the degree to which nutrient fluxes may be imbalanced.     

Adenylates as an estimate of microbial biomass C in different soil groups

Adenylate (i.e. adenosine tri- (ATP), di- (ADP) and monophosphates (AMP)) and microbial biomass C data were collected over a wide range of sites including forest floor layers and forest, grassland and arable soils. Microbial biomass C was measured by fumigation extraction and adenylates after alkaline Na₃PO₄/DMSO/EDTA extraction and HPLC detection. Our aims were (1) to test whether the sum of adenylates is a better estimate for microbial biomass than the determination of ATP, (2) to compare our conversion values with those proposed by others, and (3) to analyse whether soil properties or land use form affect the relationships between ATP, adenylates and microbial biomass C. A close relationship was found between microbial biomass C and ATP (r=0.96), but also with the sum of adenylates (r=0.96) within all appropriately conditioned soil samples (n=112). In the mineral soil (n=98), the geometric means of the ATP-to-microbial biomass C ratio and the adenylates-to-microbial biomass C ratio were 7.4 and 11.4 μmol g⁻¹, respectively. The mean ratios did not differ significantly between the different texture classes and land use forms. In the forest floor, the ATP-to-microbial biomass C ratio and the adenylates-to-microbial biomass C ratio were both roughly two-thirds of those of the mineral soil. The average adenylate energy charge (AEC) of all soil samples was 0.79 and showed a strong negative relationship with the soil pH (r=−0.69). However, the AEC is presumably only indirectly affected by the soil pH.     

Translational regulators maintain totipotency in the Caenorhabditis elegans germline

The molecular mechanisms that maintain totipotency of the germline are not well understood. Here, we show that two conserved translational regulators, MEX-3 and GLD-1, are essential for maintaining totipotency in the Caenorhabditis elegans germline. In mex-3 gld-1 mutants, germ cells transdifferentiate into various somatic cell types such as muscles or neurons. Our findings implicate RNA regulation in the maintenance of totipotency, suggest that multiple mechanisms maintain totipotency at different stages of germline development, and establish a genetically tractable model for studying the development of teratomas.