Retinal cryptochrome in a migratory passerine bird: a possible transducer for the avian magnetic compass

The currently discussed model of magnetoreception in birds proposes that the direction of the magnetic field is perceived by radical-pair processes in specialized photoreceptors, with cryptochromes suggested as potential candidate molecules mediating magnetic compass information. Behavioral studies have shown that magnetic compass orientation takes place in the eye and requires light from the blue-green part of the spectrum. Cryptochromes are known to absorb in the same spectral range. Because of this we searched for cryptochrome (CRY) in the retina of European robins, Erithacus rubecula, passerine birds that migrate at night. Here, we report three individually expressed cryptochromes, eCRY1a, eCRY1b, and eCRY2. While eCRY1a and eCRY2 are similar to the cryptochromes found in the retina of the domestic chicken, eCRY1b has a unique carboxy (C)-terminal. In light of the radical-pair model, our findings support a potential role of cryptochromes as transducers for the perception of magnetic compass information in birds.     

The Hypercycle

Topologic methods are used to characterize a particular class of self-replicative reaction networks: the hypercycles. The results show that the properties of hypercycles are sufficient for a stable integration of the information contained in several self-replicative units. Among the catalytic networks studied, hypercyclic organization proves to be a necessary prerequisite for maintaining the stability of information and for promoting its further evolution. The techniques used in this paper, though familiar to mathematicians, are introduced in detail in order to make the logical arguments accessible to the nonmathematician.     

Lebendbeobachtung der Kernteilung bei Basidiomyceten

The Science of Nature -     

Interspecific aggression in colonies of the slave-making ant Harpagoxenus sublaevis

Colonies of the slave-making ant, Harpagoxenus sublaevis, may simultaneously contain workers of several Leptothorax slave species. We observed aggressive interactions among slave-makers, between slavemakers and slaves, and among slaves in 11 mixed colonies. The first two types of aggression appear to be correlated with reproductive competition for the production of males. Aggressive interactions among slaves, however, occurred mainly between slaves belonging to different species. In two colonies, in which one slave species clearly outnumbered the other, the majority attacked and finally expelled all nestmates belonging to the minority species. Our observations thus suggest that in Harpagoxenus colonies a homogeneous colony odor is not always achieved and that heterospecific slaves may occasionally be mistaken for alien ants. Gas chromatographic analyses of ants from mixed colonies similarly show that cuticular hydrocarbon profiles may differ strongly between heterospecific nestmate slaves.     

Guide values for contaminated sites in Baden-Württemberg

The treatment of hazardous sites in Baden-Württemberg is based on three legal documents: the state waste disposal art (LAbfG, 1990), the assessment committee directive (KommissionsVO, 1990), and the guide values directive (UM & SM B-W, 1993). The guide values directive was commonly issued by the Ministry of Labor, Health and Social Affairs and the Ministry of the Environment of the state of Baden-Württemberg (UM & SM B-W, 1993) and contains a three-level hierarchy of numerical criteria and rules which serve as both screening levels during the investigation and as remediation objectives. The decision for the appropriate level of remediation is based on feasibility and environmental balance considerations. The levels are ordered as follows:

? Level 1 (Background-Values) On principle, all remediations have to be based first on background levels. In the case of lack of feasibility or negative environmental balance for level-1 objectives use-specific requirements are considered next.

? Level 2 (Assessment-Values for Worst Case Exposure Conditions) The generic requirements underlying level 2 afford appropriate protection for humans regarding the most sensitive uses of the environment. At least four resources are considered on this level: Ground-water as such and its use, the health of humans on contaminated sites, and soil with respect to growth and quality of plants. Barriers against migration of the contaminants, the effect of dilution, and abandonment of certain uses, etc., are not taken into consideration on level 2.

? Level 3 (Site-Specific Requirements) Lack of feasibility or a negative environmental balance of level-2 objectives lead to consideration of site-specific circumstances which may alleviate the requirements. With respect to groundwater, the distinction is again necessary between groundwater as a resource and the use of groundwater. On level 3 the guideline gives rules of how to derive site-specific remediation objectives for groundwater in the form of concentrations and fluxes of contaminants after taking into account barriers, dilution, and the abandonment of uses.

The guideline is the only directive of its kind in the world that regulates both concentrations and fluxes of contaminants into groundwater.     

Human Neuroblastoma: From Basic Science to Clinical Debut of Cellular Oncogenes

MYCN  , which identifies a group of patients who have a particularly dire prognosis. Amplified MYCN is used today as a prognostic marker on which therapy design is based to a large extent. An unusual aspect of neuroblastoma is the high rate at which tumors regress spontaneously, even in infants with extensive liver involvement and numerous subcutaneous nodules. Identifying the molecular and cellular basis of spontaneous regression could result in improved therapeutic approaches. Neuroblastoma is a model tumor with many fascinating aspects but has remained a challenge to the pediatric oncologist