Eine Absorptionsschicht der hohen Atmosphäre?

Summary The varying intensity of the shortest wave-length 2863 Å of the solar spectrum points to the possibility that labile absorption spectra exist in the higher atmosphere. As spectrographs mounted on V-2 rockets have showen that at a height of 55 km an absorption exists around 2800 Å besides the strong Frauenhofer-lines, and as the termination of the solar spectrum at 2400 Å appears remarkably abrupt, we may suspect a new absorption in the high atmosphere, for which possibly the oxides of nitrogen, primarily the NO ₂ ⁺ or the NO⁺ ion, are responsible.     

Aminopeptidase N is a major receptor for the entero-pathogenic coronavirus TGEV.

Coronaviruses, like many animal viruses, are characterized by a restricted host range and tissue tropism. Transmissible gastroenteritis virus (TGEV), a major pathogen causing a fatal diarrhoea in newborn pig, replicates selectively in the differentiated enterocytes covering the villi of the small intestine. To investigate the molecular determinants of the infection, we characterized the surface molecule used by the virus for binding and entry into host cells. Here we report that aminopeptidase N, an ectoenzyme abundantly expressed at the apical membrane of the enterocytes, serves as a receptor for TGEV. Monoclonal antibodies were selected for their ability to block infection by TGEV of porcine cell lines. They recognized a brush-border membrane protein of M(r) 150K, which was identified as aminopeptidase N by amino-terminal sequencing. Two lines of evidence supported the view that the peptidase itself acts as a receptor. First, virions bound specifically to aminopeptidase N that was purified to homogeneity. Second, recombinant expression of aminopeptidase N conferred infectivity by TGEV to an otherwise non-permissive cell line.     

Soluble polysialylated NCAM: a novel player of the innate immune system in the lung

Posttranslational modification of the neural cell adhesion molecule (NCAM) by polysialic acid (polySia) is well studied in the nervous system and described as a dynamic modulator of plastic processes like precursor cell migration, axon fasciculation, and synaptic plasticity. Here, we describe a novel function of polysialylated NCAM (polySia-NCAM) in innate immunity of the lung. In mature lung tissue of healthy donors, polySia was exclusively attached to the transmembrane isoform NCAM-140 and located to intracellular compartments of epithelial cells. In patients with chronic obstructive pulmonary disease, however, increased polySia levels and processing of the NCAM carrier were observed. Processing of polysialylated NCAM was reproduced in a mouse model by bleomycin administration leading to an activation of the inflammasome and secretion of interleukin (IL)-1β. As shown in a cell culture model, polySia-NCAM-140 was kept in the late trans-Golgi apparatus of lung epithelial cells and stimulation by IL-1β or lipopolysaccharide induced metalloprotease-mediated ectodomain shedding, resulting in the secretion of soluble polySia-NCAM. Interestingly, polySia chains of secreted NCAM neutralized the cytotoxic activity of extracellular histones as well as DNA/histone-network-containing “neutrophil extracellular traps”, which are formed during invasion of microorganisms. Thus, shedding of polySia-NCAM by lung epithelial cells may provide a host-protective mechanism to reduce tissue damage during inflammatory processes.     

Ecdysteroid hormone action

Several reviews devoted to various aspects of ecdysone research have been published during the last few years. Therefore, this article concentrates mainly on the considerable progress in ecdysone research observed recently, and will cover the results obtained during the last 2 years. The main emphasis is put on the molecular mode of ecdysteroid receptor-mediated hormone action. Two examples of interaction with other hormonal signalling pathways are described, namely crosstalk with juvenile hormone and insulin. Some selected, recently investigated examples of the multitude of hormonal responses are described. Finally, ecological aspects and some practical applications are discussed.     

Zur Charakterisierung zellteilungswirksamer Substanzen an der Gewebekultur

Ohne Zusammenfassung     

Qualitative microchemical analysis by microradiography with fluorescent screen

Zusammenfassung Durch die Anwendung eines sehr feinkornigen Fluoreszenzschirmes statt eines photographischen Filmes bei der Mikroradiographie und Betrachtung des erhaltenen Bildes im Mikroskop ist es in gewissen Fällen möglich, direkt im mikroskopischen Objekt eine qualitative mikrochemische Analyse durchzuführen.     

Pupils' Research into School Culture: A Photographic Approach to Evaluation

Pupils are given a camera as a research instrument to explore the culture of their school as a learning organization. In researching through photographying they can become active participants in evaluation and development, and the results in the form of photo presentations offer valuable insights into how young people experience school life through the eyes of a camera. The pupils' photographic images convey a different meaning from what they would express verbally or answer in a questionnaire. Moreover, the pupils have to collaborate and work toward consensus building in deciding on images they find worth being photographed and form little communities of action researchers when they explore their daily school settings from a different perspective. By doing this kind of action research through taking photos, they have the opportunity to interrupt the usual school pattern teacher asks, pupil answers, teacher evaluates according to a right/wrong system. In this sense, photos used as a means of self-evaluation can become a valuable instrument leading to institutional change.