Bose-Einstein condensates: microscopic magnetic-field imaging

Today's magnetic-field sensors are not capable of making measurements with both high spatial resolution and good field sensitivity. For example, magnetic force microscopy allows the investigation of magnetic structures with a spatial resolution in the nanometre range, but with low sensitivity, whereas SQUIDs and atomic magnetometers enable extremely sensitive magnetic-field measurements to be made, but at low resolution. Here we use one-dimensional Bose-Einstein condensates in a microscopic field-imaging technique that combines high spatial resolution (within 3 micrometres) with high field sensitivity (300 picotesla).     

Inversin, the gene product mutated in nephronophthisis type II, functions as a molecular switch between Wnt signaling pathways

Cystic renal diseases are caused by mutations of proteins that share a unique subcellular localization: the primary cilium of tubular epithelial cells. Mutations of the ciliary protein inversin cause nephronophthisis type II, an autosomal recessive cystic kidney disease characterized by extensive renal cysts, situs inversus and renal failure. Here we report that inversin acts as a molecular switch between different Wnt signaling cascades. Inversin inhibits the canonical Wnt pathway by targeting cytoplasmic dishevelled (Dsh or Dvl1) for degradation; concomitantly, it is required for convergent extension movements in gastrulating Xenopus laevis embryos and elongation of animal cap explants, both regulated by noncanonical Wnt signaling. In zebrafish, the structurally related switch molecule diversin ameliorates renal cysts caused by the depletion of inversin, implying that an inhibition of canonical Wnt signaling is required for normal renal development. Fluid flow increases inversin levels in ciliated tubular epithelial cells and seems to regulate this crucial switch between Wnt signaling pathways during renal development.     

Amino acid changes in the developing feline brain

Résumé La teneur en glutamine dans le cerveau des chatons nouveau-nés au cours de la maturation cérébrale est comparable à celle des animaux adultes. Les concentrations en acide glutamique et en GABA augmentent et vers la fin du premier mois postnatal correspondent au niveau des adultes.     

Untersuchungen über die alkylierende Wirkung von14C-Methylnitrosoharnstoff und 1-14C-Äthylnitrosoharnstoff

Summary Alkylation of RNA from brain, liver and kidney in rats after application of¹⁴C-methylnitrosourea and 1-¹⁴C-ethylnitrosourea was investigated. After administration of¹⁴C-methylnitrosourea the amount of 7-methylguanine in the RNA of brain and liver is about the same. Analogic experiments using 1-¹⁴C-ethylnitrosourea showed no alkylation of the RNA in the organs investigated. This leads to the conclusion that there is no direct correlation between the alkylation of RNA and organotropic carcinogenic activity of the compounds studied.

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Herrn Professor Dr.O. Eichler zum 70. Geburtstag gewidmet.     

On the metabolism of prostaglandins by rat brain homogenate

Summary Using radio-immuno assays for prostaglandins and prostaglandin metabolites, three prostaglandin metabolizing enzymes were found in the 100,000×g supernatant of rat brain, 15-hydroxy-prostaglandin-dehydrogenase, ¹³ and prostaglandin E-9-keto-reductase. Specific activity of the latter enzyme was highest in striatum and midbrain and lowest in cortex, cerebellum and spinal cord.This work was supported by the Deutsche Forschungsgemeinschaft (SFB No. 70).     

Interaction of bride of sevenless membrane-bound ligand and the sevenless tyrosine-kinase receptor

During development of the Drosophila retina, the R8 photoreceptor neuron induces a neighbouring cell to assume an R7 cell fate. Genetic data suggest that the induction is mediated by two transmembrane proteins encoded by bride of sevenless and sevenless. A direct interaction between these two proteins was demonstrated by the heterotypic aggregation of cell lines expressing them. In the developing eye the sevenless-dependent internalization of bride of sevenless by the R7 precursor cell provides evidence for a direct interaction between these two proteins in vivo.     

Perforin and its role in T lymphocyte-mediated cytolysis

The killing mediated by cytotoxic T lymphocytes (CTL) represents an important mechanism in the immune defence against tumors and virus infections. The lytic mechanism has been proposed to consist of a polarized secretion of granule-stored molecules, occurring on effector-target cell contact. By electron microscopy, membrane deposited, pore-like lesions are detected on the target cell membrane during cytolysis by CTL. These structures resembled strikingly pores formed during complement attack.Granules of CTL isolated by nitrogen cavitation and Percoll gradient centrifugation were shown to retain cytotoxic activity. Further purification of proteins stored in these granules led to the discovery of a membranolytic protein named perforin which was capable of polymerizing into pore-like structures. In addition to this cytolytic protein, a set of serine esterases was found as well as lysosomal enzymes and proteoglycans, whose function are not yet clearly defined. The role of perforin in the cytotoxic process is currently being explored by ablating the active gene in mice.     

Composition and distribution patterns of chewing lice of two neotropical species of Turdus

We analyzed the prevalence and intensity of chewing lice on two neotropical species of Turdus and identified morphological parameters of birds influencing louse population dynamics. The study was conducted in southernmost Rio Grande do Sul state (RS), Brazil, between July 2009 and June 2010. Chewing lice were collected by dust-ruffling. The prevalence of chewing lice on both species of Turdus was high. Chewing lice from both species of Turdus exhibit similar composition and distribution patterns. However, chewing lice were more abundant on Turdus rufiventris, whereas species richness was higher on Turdus amaurochalinus. Myrsidea and Brueelia were the most prevalent and abundant genera on both host species in all seasons of the year. A predominance of chewing louse females and adults was observed. Aggregated distributions were observed. Body length was the only morphological parameter correlated with louse abundance, suggesting that specimens with a larger body have a higher abundance of lice.