The parthenogenetic Marmorkrebs (marbled crayfish) produces genetically uniform offspring

Genetically identical animals are very much in demand as laboratory objects because they allow conclusions about environmental and epigenetic effects on development, structures, and behavior. Furthermore, questions about the relative fitness of various genotypes can be addressed. However, genetically identical animals are relatively rare, in particular, organisms that combine a high reproduction rate and a complex organization. Based on its exclusively parthenogenetic reproduction mode, it has been suggested that the Marmorkrebs (Crustacea, Decapoda, Astacida), a recently discovered crayfish, is an excellent candidate for research addressing the aforementioned questions. However, until now, a study using molecular markers that clearly proves the genetic uniformity of the offspring has been lacking. Here, with this first molecular study, we show that this crayfish indeed produces genetically uniform clones. We tested this with 19 related individuals of various generations of a Marmorkrebs population by means of six different microsatellite markers. We found that all examined specimens were identical in their allelic composition. Furthermore, half of the analyzed loci were heterozygous. These results and the absence of meioses in previous histological studies of the ovaries lead us to conclude the Marmorkrebs propagates apomictically. Thus, a genetically uniform organism with complex morphology, development, and behavior is now available for various laboratory studies.     

Interception of dry and wet deposited radionuclides by vegetation

Interception of dry and wet deposited radionuclides by vegetation is a key process in radioecological models that assess ingestion doses to the population following releases of radionuclides to the atmosphere. Radionuclides may be deposited during precipitation or as dry particles. Interception of wet deposited radionuclides is the result of a complex interaction of the vegetative development of the plant canopy, the amount of rainfall, and the chemical form of radionuclides. For the interception of dry deposits, particle size is a key parameter; interception is more effective for small particles and reactive gases. Due to the dependence on plant development, interception of both dry and wet deposits is subject to pronounced seasonality.     

Improving the adsorption capacity and solid structure of natural volcanic soil using a foaming-sintering process based on recycled polyethylene terephthalate (PET).

The volcanic soils of southern Chile have demonstrated a high capacity to adsorb environmental pollutants, but for an industrial application, a stable solid material is necessary. The objective of this work was to produce a stable ceramic material through a process involving volcanic soil-polyurethane foam produced with recycled polyethylene terephthalate (PET)-polyols, and further thermal treatment. The selected foam formulation with 35.4% volcanic soil (< 63 microm) seems to be the most suitable for thermal treatment, with temperature steps at 700, 850, 1000 and 1200 degrees C. The porous ceramic material obtained has a stable solid form and an improved chlorophenols adsorption capacity (comparable to natural zeolites) that makes it suitable for advanced wastewater treatment and landfill leachate depuration.     

Quantification of sources of PCBs to the atmosphere in urban areas: A comparison of cities in North America, Western Europe and former Yugoslavia

We present estimated emission source strengths of seven polychlorinated biphenyl (PCB) congeners for Banja Luka, a city that was affected by the civil war in Bosnia and Hercegovina (former Yugoslavia) in the 1990s. These emission estimates are compared to PCB emission rates estimated for the cities of Zurich, Switzerland, and Chicago, USA using an approach that combines multimedia mass balance modeling and measurement data. Our modeled per-capita emission estimates for Banja Luka are lower by a factor of ten than those for Zurich and Chicago, which are similar. This indicates that the sources of PCB emissions in Banja Luka are likely to be weaker than in the Western European and North American cities which show relatively high PCB emissions. Our emission rates from the three cities agree within a factor of ten with emission estimates from a global PCB emission inventory derived from production and usage estimates and emission factors.     

Uptake of 203Hg++ and 115 mCd++ by Chlamydomonas reinhardi under various conditions

The uptake of radioactively labeled mercury and cadmium ions by living and dead cells of Chlamydomonas reinhardi WT⁺ was measured at 25 °C under minimal and optimal conditions (dark/nitrogen or light/air, respectively). In each case, incorporation was completely independent of external energy. Living and dead cells incorporated almost the same amount of the added heavy metal ions; after about 4 to 8 hours, saturation was obtained. Furthermore, the distribution of mercury in the system of algea/culture medium/gas phase and the amount of mercury and cadmium adsorbed by cells were studied.