Schadstoffbelastung durch Persorption von Bodenpartikeln

The term persorption describes the paracellular uptake of particles from the digestive tract. It has been shown that solid, hard microparticles such as starch granules, cellulose particles, fibres and crystals are incorporated from the digestive tract. It is likely that an uptake of soil contaminants may also occur via this mechanism, thereby increasing the health risks of children through soil ingestion. The aim of this study was to evaluate the significance of such soil contaminant absorption via this mechanism using data from the literature. Since no information was available on the persorption of soil particles, studies using other models had to be evaluated. The results of these studies show that a persorption of soil particles must be expected. The maximum persorption rate occurs for diameters of <35 μm which is in the range of diameters of street dust, clay and coarse clay. The persorption of these particles is therefore of significance. Data from the literature, however, does not allow an estimation of the magnitude of persorption of such soil particles. Basically, it is conceivable that a relevant ingestion of less mobile pollutants is possible through their persorption in the gastrointestinal tract. Aside from an increased internal exposure via the persorption of soil particles carrying contaminants, additional health risks may occur through the long-term deposit of such particles, the presence of potential allergens as well as through the embolisation of small vessels.     

The spectral sensitivity of a passerine bird is highest in the UV

The work was supported by a grant from the DFG, SFB 4, E6.     

Ontogenetic data and the evolutionary origin of the mammalian scapula

One of the most useful diagnostic therian features is the division of the lateral surface of the scapula into two fossae separated by a scapular spine. A new model to describe this evolutionary innovation based on ontogenetic data is provided, consistent with information provided by recent fossil discoveries. The development of the scapula in three didelphid and one dasyurid marsupials using histological sections was studied. Only the ventral, acromial portion of the scapular spine, which originates from the anterior margin of the scapular blade, is preformed in cartilage. The major dorsal portion is formed at a later stage by appositional bone, which expands from the perichondral ossification of the scapula into an intermuscular aponeurosis between the supra-and infraspinatus muscles. This intermuscular aponeurosis inserts more or less in the middle of the lateral surface of the developing scapula. Thus, the floor of the supraspinous fossa is already present at the beginning of scapular development, simultaneous with the infraspinous fossa. The portion of the scapular spine that is situated dorsal to the acromial process is hypothesized to be a neomorphic structure of therians. The dorsal portion of the scapular spine evolved as additional attachment for powerful supraspinatus and infraspinatus muscles meeting near the middle of the lateral scapula.