Chlorierte Kohlenwasserstoffe in Brutv?geln aus dem Binnenland Niedersachsens

Zusammenfassung Rückstände chlorierter Kohlenwasserstoffe in Eiern und Lebern von im Binnenland Niedersachsens brütenden Vogelarten — Feldsperling, Mehlschwalbe, Weißstorch, Graureiher, Saatkrähe, Stockente und andere Arten — werden angegeben und deren Abhängigkeit von Brutort, Nahrung und Zugverhalten diskutiert.

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Chlorinated hydrocarbons of some bird species breeding in the inland of Lower Saxony (FRG)

Summary Residues of chlorinated hydrocarbons in eggs and livers of some bird species — Tree Sparrow, House Martin, White Stork, Heron, Rook, Mallard, and further species — are presented. The dependence on place of breeding, food web, and migration is discussed.

     

Two recurrent nonsense mutations and a 4 bp deletion in a quasi-symmetric element in exon 37 of the NF1 gene

We screened a total of 92 unrelated patients with neurofibromatosis type 1 (NF1) for mutations in exon 37 of the NF1 gene, by using temperature gradient gel electrophoresis. Two novel mutations were found: a 4 bp deletion in a so-called quasi-symmetric element (6789delTTAC) and a recurrent nonsense mutation, which was identified in two unrelated patients, at codon 2264 (C6792A). The independent origin of the latter mutation in two families was confirmed by haplotype analysis. The nonsense mutation and the 4 bp deletion are both predicted to lead to a truncated protein product lacking the Cterminal 20% (aproximately) of its sequence. The occurrence of three independent mutations among 92 NF1 patients at codons 2263–2264 (exon 37) suggests that a specific search for mutations in this area should be undertaken in screening programs for NF1 mutations.     

Monoclonal antibody directed against RNA polymerase II of Drosophila melanogaster

Summary Monoclonal antibodies were raised against purified RNA polymerase II (or B) from Drosophila melanogaster. The antibody produced by one hybridoma cell clone was found to be directed against the two large subunits of the enzyme. The absence of antibodies directed against proteins possibly contaminating the antigens used for immunization allowed us to identify RNA polymerase unequivocally in interbands and puffs of polytene chromosomes. Within a single heat shock puff (87C1) RNA polymerase was found to be clustered in two separate areas suggesting two distint regions of RNA polymerase activity in this puff.Abbreviations FITC fluorescein isothiocyanate - PAGE polyacrylamide gel electrophoresis - PBS phosphate buffered saline - SDS sodium dodecyl sulfate - Enzyme DNA-dependent RNA polymerase or nucleotide-triphosphate - RNA nucleotidyltransferase (EC 2.7.7.6)     

Function of laccase in the white-rot fungus Fomes annosus

1. Thioglycolic acid, a Cu-chelating agent, totally inhibited extracellular laccase activity without affecting growth and morphology of Fomes annosus.
2. In the presence of thioglycolic acid Fomes annosus cleaved high molecular weight lignosulfonate with a molecular weight range of 2×10⁶ to 1000. In the absence of thioglycolic acid the polymerizing activity of laccase prevented the detection of lignosulfonate breakdown products.
3. Oxidative polymerization of a lignin monomer, coniferyl alcohol, occurred in the presence but not in the absence of laccase activity.
4. Catechol and guaiacol added to the medium at a concentration of 2 mmol, are normally oxidized by fungal laccase and strongly inhibit growth. Presence of thioglycolic acid prevented the oxidation of these phenols and simultaneously permitted normal growth.

     

Induction of synchronous differentiation (encystment) in Physarum polycephalum myxamoebae

Encystment of Physarum polycephalum myxamoebae, grown under nearly identical physiological conditions as plasmodia is induced by transfer to a salts medium containing 0.5 M mannitol or mannose. After 24 h induction approximately 50% of amoebae had differentiated to cells which were identified to be young cysts by light and electron microscopy. Several other polyols, sugars, biogenic amines, and a starvation period from 24 h to one week caused no reproducible cyst formation. In contrast to the formation of dormant forms in the plasmodial stage of the life cycle, the induction of cysts and their germination to amoebae are not inhibited neither by actinomycin C nor by cycloheximide. In addition, the isoenzyme spectra of aminopeptidases and acid proteases remain nearly identical in growing and differentiating amoebae.Abbreviations SD semi-defined BSS basal salts solution The investigation is a part of the Ph. D. thesis of A. Haars, Göttingen, 1976     

Stalk Formation and Its Inhibition in Caulobacter crescentus

Estimates of average rates of stalk formation over several generations of growth in Caulobacter crescentus showed that long-stalked Sk1 mutant and phosphate-starved wild-type cultures produce stalk material at about twice the rate of wild-type C. crescentus grown with adequate nutrients. Thus, the long stalks of Sk1 or phosphate-starved caulobacters are not merely a function of their longer doubling times. Inhibition of cell division of Sk1 418 with mitomycin C (MC) caused production of cellular filaments and resulted in inhibition of stalk formation. There was no appreciable decrease in total cell mass or in rates of ribonucleic acid and protein synthesis in the MC-treated cultures as compared with controls, but stalk formation, which is normally dependent on these processes, was severely retarded. Average stalk lengths in MC-treated Sk1 cultures were 30% of those found in control cultures. MC-produced cellular filaments were also subjected to deoxyribonucleic acid analysis and ultrastructural examination. The deoxyribonucleic acid content of MC-treated bacteria was about 50 to 60% that of untreated bacteria. Hydroxyurea also was found to produce some cellular filaments and shorter stalks, but with accompanying decreases in growth rate and yield.     

Arabidopsis Sec1/Munc18 Protein SEC11 Is a Competitive and Dynamic Modulator of SNARE Binding and SYP121-Dependent Vesicle Traffic

The Arabidopsis thaliana Qa-SNARE SYP121 (=SYR1/PEN1) drives vesicle traffic at the plasma membrane of cells throughout the vegetative plant. It facilitates responses to drought, to the water stress hormone abscisic acid, and to pathogen attack, and it is essential for recovery from so-called programmed stomatal closure. How SYP121-mediated traffic is regulated is largely unknown, although it is thought to depend on formation of a fusion-competent SNARE core complex with the cognate partners VAMP721 and SNAP33. Like SYP121, the Arabidopsis Sec1/Munc18 protein SEC11 (=KEULE) is expressed throughout the vegetative plant. We find that SEC11 binds directly with SYP121 both in vitro and in vivo to affect secretory traffic. Binding occurs through two distinct modes, one requiring only SEC11 and SYP121 and the second dependent on assembly of a complex with VAMP721 and SNAP33. SEC11 competes dynamically for SYP121 binding with SNAP33 and VAMP721, and this competition is predicated by SEC11 association with the N terminus of SYP121. These and additional data are consistent with a model in which SYP121-mediated vesicle fusion is regulated by an unusual “handshaking” mechanism of concerted SEC11 debinding and rebinding. They also implicate one or more factors that alter or disrupt SEC11 association with the SYP121 N terminus as an early step initiating SNARE complex formation.     

Endosomes, exosomes and Trojan viruses

Retroviruses are enveloped viruses that are generally assumed to bud at the plasma membrane of infected cells. Recently it has become apparent that some of these viruses use the endocytic pathway to coordinate their assembly and release. In addition, these and some other enveloped viruses exploit the machinery that generates the internal membranes of multivesicular bodies (MVB). These observations and others have led to the suggestion that retroviruses be regarded as "viral exosomes". Here we discuss this concept and the emerging evidence that compartments of the endocytic pathway play important roles in the biogenesis of both the internal vesicles of MVB and viruses.