Affinity chromatography of soluble galactosyltransferases using an easily synthesized N-acetylglucosamine-agarose bead

Summary Agarose derivatized withp-nitrophenyl-N-acetyl--d-glucosamine was used for affinity chromatography for soluble galactosyltransferase from various sources. Moreover, this adsorbant acts as an acceptor for galactose when incubated with prepurified galactosyltransferase.This work was supported by a grant from the USPHS (grant No. 1 PO1 CA 14294-2).     

Unique astrocyte ribbon in adult human brain contains neural stem cells but lacks chain migration

The subventricular zone (SVZ) is a principal source of adult neural stem cells in the rodent brain, generating thousands of olfactory bulb neurons every day. If the adult human brain contains a comparable germinal region, this could have considerable implications for future neuroregenerative therapy. Stem cells have been isolated from the human brain, but the identity, organization and function of adult neural stem cells in the human SVZ are unknown. Here we describe a ribbon of SVZ astrocytes lining the lateral ventricles of the adult human brain that proliferate in vivo and behave as multipotent progenitor cells in vitro. This astrocytic ribbon has not been observed in other vertebrates studied. Unexpectedly, we find no evidence of chains of migrating neuroblasts in the SVZ or in the pathway to the olfactory bulb. Our work identifies SVZ astrocytes as neural stem cells in a niche of unique organization in the adult human brain.     

Glucoacetyldigoxosid und Glucodigoxosid,neue genuine Glykoside aus den Blättern vonDigitalis schischkinii (Ivan.) Werner

Summary A new cardiotonic pentaglycoside with the structure glucoacetyldigoxoside (digoxigenin--D-glucosido-acetyltetradigitoxoside) was isolated from the leaves ofDigitalis schischkinii (Ivan.) Werner. Its desacetyl product, glucodigoxoside has also been found in the fraction of most polar glycosides.

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Wir danken Herrn Dr. F. Kaiser, Mannheim, für die Überlassung einer Probe von Digoxosid und Herrn Prof. Dr. H. Wagner, München, für die Durchführung der Elementaranalysen und optischer Drehungen.     

ATP-sensitive potassium channels mediate survival during infection in mammals and insects

Specific homeostatic mechanisms confer stability in innate immune responses, preventing injury or death from infection. Here we identify, from a screen of N-ethyl-N-nitrosourea-mutagenized mice, a mutation causing both profound susceptibility to infection by mouse cytomegalovirus and approximately 20,000-fold sensitization to lipopolysaccharide (LPS), poly(I.C) and immunostimulatory (CpG) DNA. The LPS hypersensitivity phenotype is not suppressed by mutations in Myd88, Trif, Tnf, Tnfrsf1a, Ifnb, Ifng or Stat1, genes contributing to LPS responses, and results from an abnormality extrinsic to hematopoietic cells. The phenotype is due to a null allele of Kcnj8, encoding Kir6.1, a protein that combines with SUR2 to form an ATP-sensitive potassium channel (K(ATP)) expressed in coronary artery smooth muscle and endothelial cells. In Drosophila melanogaster, suppression of dSUR by RNA interference similarly causes hypersensitivity to infection by flock house virus. Thus, K(ATP) evolved to serve a homeostatic function during infection, and in mammals it prevents coronary artery vasoconstriction induced by cytokines dependent on TLR and/or MDA5 immunoreceptors.     

The afterglow of GRB 050709 and the nature of the short-hard gamma-ray bursts

The final chapter in the long-standing mystery of the gamma-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolution in our understanding of long-duration GRBs that followed the discovery in 1997 of their broadband (X-ray, optical and radio) afterglow emission. Here we present the discovery of the X-ray afterglow of a short-hard burst, GRB 050709, whose accurate position allows us to associate it unambiguously with a star-forming galaxy at redshift z = 0.160, and whose optical lightcurve definitively excludes a supernova association. Together with results from three other recent short-hard bursts, this suggests that short-hard bursts release much less energy than the long-duration GRBs. Models requiring young stellar populations, such as magnetars and collapsars, are ruled out, while coalescing degenerate binaries remain the most promising progenitor candidates.     

Cis-active control of mouse beta-galactosidase biosynthesis by a systemic regulatory locus.

Several higher organisms have been reported in which enzyme levels are determined genetically by sites located in close proximity to the corresponding structural genes. In several cases, these sites have been shown to act by controlling the rates of enzyme synthesis. Cis compared with trans action has been tested for those proximate regulatory sites controlling enzymes for which appropriate structural variants exist. The rate of synthesis of beta-galactosidase in mouse tissues is under the control of a regulatory locus; Bgl-s, that is tightly linked to the enzyme structural gene; we have tested the cis/trans nature of Bgl-s action by analysis of the electrophoretic mobility of the enzyme from animals heterozygous for the appropriate regulatory and structural alleles. Our results indicate that Bgl-s acts cis, controlling the expression of the structural gene located on the same chromosome.     

3′–5′-cAMP and lysosome membrane labilization

Zusammenfassung Es wird gezeigt, dass 3–5-cAMP (10^–3 M) und Theophyllin (10^–4 M) die Permeabilität derjenigen Lysosmen-Membranen steigern, die aus Rattenleberzellen in bezug auf saure Phosphatase and in bezug auf -Glucuronidase-Enzyme präpariert wurden.