Tagesperiodische Resistenzschwankungen gegenα-Strahlen

Ohne Zusammenfassung     

Salmonella serotypes isolated from human enteric processes in Recife, Pernambuco, during 1978-1980

From 13,196 faecal cultures made in Recife-Pernambuco during the period from 1978 to 1980, 1,720 strains of Salmonella were isolated. Serological typing on 1,387 of the isolates recognized 63 serotypes, 73.18% of which belonged to group B. The prevalent serotypes adding up to 1,231 strains (88.75% of the total of the isolates) were: S. typhimurium, S. saint-paul, S. poona, S. derby, S. agona, S. newport, S. oranienburg, S. infantis, S. tshiongwe and S. ndolo.     

Purification and properties of cyclic-3',5'-GMP-dependent protein kinase from the nematode Ascaris suum

A cyclic-3',5'-GMP-dependent protein kinase was purified 7400-fold from the reproductive tract of female ascarids to a specific activity of 718 nmol min-1 mg-1 (histone as substrate). The yield of the preparation was 25%. The enzyme protein obtained was homogeneous as judged by isoelectrofocusing and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The native enzyme behaved as a dimer of two 82-kDa subunits in gel permeation chromatography on Superose 12. The protein kinase was inactive in the absence of cyclic purine nucleotides. Half-maximum velocity was obtained in the presence of 18 nM cGMP, whereas 400-fold higher concentrations of cAMP were required for the same activity. The enzyme underwent autophosphorylation in first-order kinetics (rate constant 0.054 min-1), leading to maximum incorporation of 0.96 phosphate per subunit. The autophosphorylation led to a 4-fold increase in Vmax, while the Km remained almost unchanged. In an extract from the reproductive tract, cGMP-stimulated phosphorylation was primarily observed in five proteins (molecular masses of 66, 60, 43, 30, and 25 kDa). These proteins also incorporated phosphate when isolated reproductive tracts were incubated in the presence of [32P]phosphate. The phosphate content in cellular proteins was enhanced when the incubation was performed in the presence of 10(-4) M of either octyl-cAMP or octyl-cGMP. In addition to the proteins mentioned above, however, six more electrophoretic bands containing radioactive phosphate were identified after in situ labeling of reproductive tracts with radioactive phosphate.     

Multisegmental cobalt filling of the dorsal giant fibers in the nervous system of the earthworm,Lumbricus terrestris

Summary The anatomical organization of the two dorsal giant fiber systems of the earthworm Lumbricus terrestris is demonstrated in whole mounts and serial-section reconstructions based on backfillings of the ventral nerve cord with cobalt chloride. Both the medial and lateral fiber systems can be labeled selectively over more than ten body segments. They show a characteristic segmental pattern of collaterals with some modification in tail segments and of dorsal plasma protrusions in the unpaired medial giant fiber presumably representing openings in the myelin sheath. We found no multisegmental cobalt transport in other large neurons of the nerve cord. Cobalt passes through the segmentai septa between consecutive axonal elements of the metameric giant fibers and presumably also through commissural contacts between specific collaterals of the lateral giant fibers. Since these sites of contact are known to represent electrical synapses, cobalt coupling may, in L. terrestris, correlate with functional electrotonic coupling.Abbreviations CL collateral of lateral giant fiber - CM collateral of medial giant fiber - GIN giant interneuron - LGF lateral giant fiber - MGF medial giant fiber - SN segmental nerve     

Protonmotive force in freshwater sulfate-reducing bacteria,and its role in sulfate accumulation in Desulfobulbus propionicus

The protonmotive force in several sulfate-reducing bacteria has been determined by means of radiolabelled membrane-permeant probes (tetraphenyl-phosphonium cation, TPP⁺, for , and benzoate for pH). In six of ten freshwater strains tested only the pH gradient could be determine, while the membrane potential was not accessible due to nonspecific binding of TPP⁺. The protonmotive force of the other four strains was between –110 and –155 mV, composed of a membrane potential of –80 to –140 mV and a pH gradient between 0.25 and 0.8 (inside alkaline) at pH_out=7. In Desulfobulbus propionicus the pH gradient decreased with rising external pH values. This decrease, however, was compensated by an increasing membrane potential. Sulfate, which can be highly accumulated by the cells, did not affect the protonmotive force, if added in concentrations of up to 4 mM. The highest sulfate accumulation observed (2500-fold), which occurred at external sulfate concentrations below 5 M, could be explained by a symport of three protons per sulfate, if equilibrium with the protonmotive force was assumed. At higher sulfate concentrations the accumulation decreased and suggested an electroneutral symport of two protons per sulfate. At sulfate concentrations above 500 M, the cells stopped sulfate uptake before reaching an equilibrium with the protonmotive force.Abbreviations CCCP carbonyl cyanide m-chlorophenylhydrazone - MOPS morpholinopropanesulfonic acid - TPP⁺ tetraphenylphosphonium cation - EDTA ethylenediaminetetraacetic acid - pH transmembrane pH gradient (pH_in-pH_out) - transmembrane electrical potential difference     

Types of sesquiterpene-coumarin ethers from Achillea ochroleuca and Artemisia tripartita

In addition to known derivatives, four new sesquiterpene-coumarin ethers were isolated from the roots of Achillea ochroleuca and Artemisia tripartita and identified by ¹H and ¹³C NMR spectroscopy, including lanthanide induced shifts. The new compounds are isofraxidin derived ethers which differ from the previously described derivatives by ring cleavage and methyl migration within the terpenoid unit. The chemosystematic importance of sesquiterpene-coumarin ether accumulation within the two genera is briefly discussed.     

Differenzierung in Schilddrüsenkulturen erwachsener Hühner

Zusammenfassung Ebeling hat im Jahre 1925 über Differenzierung und Follikelbildung in Schilddrüsenkulturen 18–19 Tage alter Hühnerembryonen berichtet. Diese Versuche wurden mit den Schilddrüsen erwachsener Hähne nachgeprüft. Dabei zeigte es sich, daß unter den von Ebeling angegebenen Bedingungen keine morphologische Differenzierung eintritt. Die von ihm beobachteten und fälschlich als neu entstanden bezeichneten Follikel sind Reste der Mutterstücke, d.h. des ursprünglich ausgepflanzten voll ausdifferenzierten Schilddrüsenfragmentes.     

Fusion of cultured dog kidney (MDCK) cells: I. Technique,fate of plasma membranes and of cell nuclei

Summary The evaluation of the intracellular signal train and its regulatory function in controlling transepithelial transport with electrophysiological methods often requires intracellular measurements with microelectrodes. However, multiple impalements in epithelial cells are hampered by the small size of the cells. In an attempt to avoid these problems we fused cells of an established cell line, Madin Darby canine kidney cells, originally derived from dog kidney, to giant cells by applying a modified polyethylene glycol method. During trypsin-induced detachment from the ground of the petri dish, individual cells grown in a monolayer incorporate volume and mainly lose basolateral plasma membrane by extrusion. By isovolumetric cell-to-cell fusion, spherical giant cells are formed within 2 hr. During this process a major part of the individual cell plasma membranes is internalized. Over three weeks following cell plasma membrane fusion degradation of single cell nuclei and cell nuclear fusion occurs. We conclude that this experimental approach opens the possibility to investigate ion transport of epithelia in culture by somatic cell genetic techniques.