Showing papers by "University of Geneva published in 1986"
TL;DR: Transcriptionally active nuclear extracts have been prepared from rat liver, brain, and spleen and the adenovirus-2 major late promoter directs efficient transcription by RNA polymerase II in all of these extracts, whereas the promoter of the mouse albumin gene is significantly used only in the liver extract.
1,149 citations
TL;DR: An algorithm for computing Liapunov exponents from an experimental time series is analyzed and a hydrodynamic experiment is investigated.
Abstract: We analyze in detail an algorithm for computing Liapunov exponents from an experimental time series. As an application, a hydrodynamic experiment is investigated.
860 citations
TL;DR: In this article, DNA fragments attached to the nuclear scaffold (SARs) both 5′ and 3′ of three Drosophila genes, defining looped domains ranging from 4.5 to 13 kb.
540 citations
TL;DR: Several lines of evidence are presented that establish the identity of SC1 as topoisomerase II as well as some micrographs of histone-depleted chromosomes that provide evidence of the substructural organization of the scaffold.
500 citations
TL;DR: The results suggest that protein transport through the Golgi stack is mediated by a new type of coated vesicle that does not contain clathrin, and the concentration of G protein in the coated buds reflects the local concentration ofGprotein in the cisternae, raising the possibility that the GolGI coated vESicles may be "bulk" membrane carriers.
468 citations
TL;DR: The generation of HLA-DR polymorphism within the DRw52 supertypic group can thus be accounted for by a succession of gene duplication, divergence and gene conversion.
Abstract: The polymorphic HLA-DR beta-chains are encoded within the human major histocompatibility complex (MHC) by multiple loci resulting from gene duplications. Certain DR haplotypes can be grouped into families based on shared structural factors. We have studied the molecular basis of HLA-DR polymorphism within such a group which includes the haplotypes DR3, DR5 and DRw6. Molecular mapping of the DR beta-chain region allows true allelic comparisons of the two expressed DR beta-chain loci, DR beta I and DR beta III. At the more polymorphic locus, DR beta I, the allelic differences are clustered and may result from gene conversion events over very short distances. The gene encoding the HLA-DR3/Dw3 specificity has been generated by a gene conversion involving the DR beta I and the DR beta III loci of the HLA-DRw6/Dw18 haplotype, as recipient and donor gene, respectively. Based on which allele is found at DR beta III, the less polymorphic locus, two groups of haplotypes can be defined: DRw52a and DRw52b. The generation of HLA-DR polymorphism within the DRw52 supertypic group can thus be accounted for by a succession of gene duplication, divergence and gene conversion.
288 citations
TL;DR: It is shown that the attachment fragment is tightly associated with protease‐sensitive material, whereas the solubilized fragments are relatively protein‐free.
Abstract: Previous experiments have identified a 657-bp restriction fragment in the non-transcribed region of the Drosophila histone gene cluster that is specifically associated with the histone-depleted nuclear scaffold. The remaining fragments of the 5-kb histone repeat were shown to be readily released from the scaffold; hence it was proposed that the tandemly repeated cluster of histone genes forms a series of 5-kb loops restrained by a nuclear substructure at the sites of attachment. Here we show that the attachment fragment is tightly associated with protease-sensitive material, whereas the solubilized fragments are relatively protein-free. Exonuclease III digestion has been used to map the location of protein complexes on the attachment fragment. We have defined two regions of ~200 bp whose borders provide kinetic barriers to exonuclease III degradation. They are separated by a nucleaseaccessible region of ~100 bp. The protected regions are sufficient to mediate association of the fragment with the histonedepleted nuclei. Sequence analysis reveals an enrichment for sequences closely related to the topoisomerase II cleavage consensus in these two domains.
283 citations
TL;DR: The African Clawed Frogs of the genus Xenopus, which comprises bisexual species of several different ploidy levels, represent a promising model for an experimental approach to the many problems associated with a polyploid condition.
252 citations
TL;DR: The translation and splicing signals in C. reinhardtii are similar to those of other eukaryotes, but the transcription signals are less conserved and the highly biased codon usage is very unusual.
240 citations
TL;DR: An improvement in the detection by nucleic acid hybridization of size-fractionated RNA immobilized to nylon-based membranes is described, with increased signals of between 10 and 40 fold were observed, depending on the species of transcript tested.
Abstract: An improvement in the detection by nucleic acid hybridization of size-fractionated RNA immobilized to nylon-based membranes is described. Electrophoretic transfer of RNA to nylon membranes permits a quantitative determination of different RNA transcripts on the same membrane after sequential hybridization using different 32P-labeled DNA probes. UV corsslinking of the RNA to the nylon membrane increased the intensity of the radioactive signals. Using the method reported here, increased signals of between 10 and 40 fold were observed, depending on the species of transcript tested. Moderately abundant as well as rare transcripts can easily be detected in as little as 5 μg total cellular RNA.
236 citations
TL;DR: Ooids occurring in the shallow-water Purbeckian carbonate sediments of the Jura mountains can be grouped into six types: small, medium, large, irregular, coarse, fine, and coarse as discussed by the authors.
Abstract: Ooids occurring in the shallow-water Purbeckian carbonate sediments of the Jura mountains can be grouped into six types. Gradations from one type to another and coexistence of the various types are common.
Type 1 ooids are small and well rounded. They display fine concentric micritic laminae. In many cases their cortices are dissolved and replaced by void-filling spar. Microsparitic neomorphic replacement occurs locally. Type 2 ooids are large and have irregular shapes. They show fine micritic laminae and occasional layers of fine-radial crystals. They commonly evolve into oncoids. Ooids of type 3 display many fine-radial cortical laminae and are patchily micritized. They are medium in size and mostly well rounded. This type of ooid may pass into large, irregularly shaped coated grains. Type 4 ooids have 1 to 4 cortical laminae with a fine-radial structure and patchy micritization. They are medium in size and well rounded. Type 5 ooids have only one lamina with a coarse-radial structure. They are small and well rounded. Associated are spherical grains containing bundles of elongate crystals. Ooids of type 6 show superpositions of two or more different, radial and or fine micritic laminae. The cortical structure may also change laterally in the same lamina.
The preferential dissolution of type 1 ooid cortices to form oomoulds indicates a primary composition of unstable carbonate. Sedimentological features and comparison with modern ooid occurrences point to formation on high-energy sandbars in normal-marine waters. Type 2 ooids grew in marine-lagoonal environments with quiet water and abundant cyanobacteria. The radially structured ooid cortices of types 3, 4 and 5 show no dissolution features. This implies that they were originally composed of stable carbonates, or that an unstable carbonate phase was transformed into a stable one at an early stage of diagenesis. Type 3 ooids occur together with marine faunas and indicate high water energy. Ooids of type 4 and type 5 originated probably from relatively quiet water of variable salinity.
Coexistence of different ooid types and mixed forms of type 6 implies gradual or rapid changes in hydrodynamic, geochemical and microbiological conditions which were a feature of the Purbeckian depositional environments.
TL;DR: Sialic acid transfer to terminal galactose residues, a reaction known to occur in the distal Golgi shortly before secretion, is completely and rapidly inhibited in the presence of these drugs, without significant modification of the secretion rate.
Abstract: The generation of an acidic pH in intracellular organelles is required for several membrane and protein recycling processes. For instance, the internalization of ligands by receptor-mediated endocytosis is followed by the development of an acidic pH inside endosomes; this allows dissociation of the ligand, which is then transported to the lysosomes, from the receptor, which is recycled to the cell surface. There is evidence that part of this recycling process involves the distal region of the Golgi complex, where terminal glycosylation occurs: when the plasma membrane transferrin receptor is desialylated by neuraminidase treatment, it acquires new sialic acid molecules after endocytosis and before cell-surface re-expression. Golgi membranes have been shown to contain a proton pump and the distal Golgi cisternae appear to have an acidic content. Here, we have studied the effects of chloroquine and ammonium chloride, which raise the pH of acidic intracellular compartments, on the processing and secretion of immunoglobulins by plasma cells. Sialic acid transfer to terminal galactose residues, a reaction known to occur in the distal Golgi shortly before secretion, is completely and rapidly inhibited in the presence of these drugs, without significant modification of the secretion rate. This effect is accompanied by a dilatation of the Golgi cisternae and is not rapidly reversible.
TL;DR: Analysis at the genomic level of the polymorphism of one of the HLA-D subregions Hla-DR, using oligonucleotide probes specific for the polymorphic regions, is capable of distinguishing single nucleotide differences.
Abstract: The human major histocompatibility complex class II antigens of the HLA-D are highly polymorphic, surface proteins essential in the cellular interactions necessary for an immune response The analysis of this polymorphism is crucial for (i) histocompatibility matching for transplantation and (ii) understanding the association between HLA-D and certain important diseases The polymorphism of certain HLA-D haplotypes may escape detection by current methodologies Analysis at the genomic level of the polymorphism of one of the HLA-D subregions HLA-DR, using oligonucleotide probes specific for the polymorphic regions, is capable of distinguishing single nucleotide differences The DRw6 haplotype was analyzed in view of the lack of DRw6 specific sera On the basis of nucleotide sequence analysis, the DRw6 haplotype consists of at least two subtypes When analyzed with oligonucleotide probes, this split identifies new polymorphic groups that differ from the DRw6 serological subgroups
TL;DR: The molecular cloning of the gene and analysis of a complementary DNA sequence suggest that the gene encodes a serine protease which is structurally similar to proteases involved in blood clotting, peptide processing, and complement fixation pathways.
Abstract: The maternal effect gene snake is required for the establishment of the dorsal-ventral axis during the embryonic development of Drosophila. The molecular cloning of the gene and analysis of a complementary DNA sequence suggest that the gene encodes a serine protease which is structurally similar to proteases involved in blood clotting, peptide processing, and complement fixation pathways.
TL;DR: Although 78 chloroplast mutants of Chlamydomonas reinhardii are able to synthesize and to integrate the other photosystem II polypeptides in the thylakoid membranes, they are unable to assemble a stable functional Photosystem II complex.
Abstract: We have examined 78 chloroplast mutants of Chlamydomonas reinhardii lacking photosystem II activity. Most of them are unable to synthesize the 32 Kdalton protein. Analysis of 22 of these mutants reveals that they have deleted both copies of the psbA gene (which codes for the 32 Kdalton protein) in their chloroplast genome. Although these mutants are able to synthesize and to integrate the other photosystem II polypeptides in the thylakoid membranes, they are unable to assemble a stable functional photosystem II complex. The 32 Kprotein appears therefore to play an important role not only in photosystem II function, but also in stabilizing this complex.
TL;DR: Results are interpreted as reflecting a process of circuitry remodelling in the arcuate nucleus after a neuronal lesion induced by estrogen.
TL;DR: The enzymic deficiency of the debrisoquine/sparteine-type polymorphism is characterized by comparing kinetic data of subjects in vivo with their microsomal activities in vitro and with reconstituted activities of cytochrome P-450 isozymes purified from human liver.
Abstract: 1. Using the stereospecific metabolism of (+)- and (-)-bufuralol and (+)- and (-)metoprolol as model reactions, we have characterized the enzymic deficiency of the debrisoquinelsparteine-type polymorphism by comparing kinetic data of subjects in wiwo with their microsomal activities in uitro and with reconstituted activities of cytochrome P4SO isozymes purified from human liver. 2. The metabolism of bufuralol in liver microsomes of in viuo phenotyped ‘poor metabolizers’ of debrisoquine and/or sparteine is characterized by a marked increase in K,, a decrease in V,. and a virtual loss of the stereoselectivity of the reaction. These parameters apparently allow the ‘phenotyping’ of microsomes in uitro.
TL;DR: The alternative use of two in-phase AUGs on a unique mRNA is thus responsible for the synthesis of p33 and p35, the first documented example of such a mechanism in nonviral systems.
TL;DR: In this article, the loganin precursor was transformed into norbornanone 20, which upon Baeyer-Villiger oxidation led to the suitably substituted cyclo- pentane 22 from which 1-B-O-methyl lignin aglucone was rea- fily available.
TL;DR: In this article, a telephone survey was conducted to report the most recent situation that evoked strong emotional feelings in them and to describe the pattern of their reactions, and the majority of the situations reported had evoked negative emotions.
Abstract: As part of a telephone survey, respondents were asked to report the most recent situation that evoked strong emotional feelings in them and to describe the pattern of their reactions. The majority of the situations reported had evoked negative emotions. Most of the emotion-antecedent events are connected to relationships with family and friends or to work-related situations. Only happiness and anger are reported as relatively pure feeling states; most others are emotion blends, with anger/sadness and sadness/fear occurring most frequently. Facial expression changes as well as heart and muscle symptoms are reported as the most frequent reactions across all emotions, whereas other nonverbal and physiological reactions are more specific for particular emotions. By the use of factor analysis, response patterns across various components of emotional state, including affect control, are explored.
TL;DR: Results suggest a novel route for bacterial production of indigo via hydroxylation of indole, which was shown to be a precursor in the reaction sequence leading to indigo formation in E. coli.
Abstract: Cells of Escherichia coli K–12 containing a cloned fragment of Pseudomonas putida TOL plasmid pWW0 produce the dye indigo. Analysis of the cloned fragment and Tn1000 transposon insertion mutagenesis has identified the xylA gene as being responsible for this phenotype. The xylA gene specifies xylene oxidase, a relaxed specificity enzyme that hydroxylates or monooxygenates toluene and xylenes and their corresponding alcohols. Indole, which is formed from tryptophan by tryptophanase in E. coli, was shown to be a precursor in the reaction sequence leading to indigo formation. These results suggest a novel route for bacterial production of indigo via hydroxylation of indole.
TL;DR: Venustatriol, a new tetracyclic ether derived from squalene, which has anti-viral activity, has been isolated from the red alga Laurencia venusta as mentioned in this paper.
TL;DR: An algorithm is presented for solving a set of linear equations on the nonnegative orthant which can be made equivalent to the maximization of a simple concave function subject to a similar set oflinear equations and bounds on the variables.
Abstract: An algorithm is presented for solving a set of linear equations on the nonnegative orthant. This problem can be made equivalent to the maximization of a simple concave function subject to a similar set of linear equations and bounds on the variables. A Newton method can then be used which enforces a uniform lower bound which increases geometrically with the number of iterations. The basic steps are a projection operation and a simple line search. It is shown that this procedure either proves in at mostO(n2m2L) operations that there is no solution or, else, computes an exact solution in at mostO(n3m2L) operations.
Journal Article•
TL;DR: During culture SMC develop features similar to those observed in normal foetal SMC or in SMC present in atheromatous plaques; this model may be useful for the understanding of mechanisms leading to SMC differentiation and to atheroma formation.
Abstract: Cytoskeletal features of arterial smooth muscle cells (SMC) vary characteristically during development and during atheromatous plaque formation (Gabbiani et al., 1984; Kocher et al., 1985). We have analyzed the cytoskeletal features of rat aortic SMC placed in culture in the presence of 10% foetal calf serum (thus containing growth factors probably playing a role in SMC development and atheroma formation), as compared to SMC freshly isolated from the rat aortic media. Under these conditions, SMC show a typical cytoskeletal remodeling characterized by: 1) increased content of vimentin per cell, increased number of cells containing only vimentin, and decreased number of vimentin plus desmin containing cells; 2) decreased contents of actin, tropomyosin and myosin; 3) a switch in the pattern of actin isoforms with the appearance of a beta-type predominance. Some of these changes (e.g. increase of vimentin and decrease of alpha-type actin) are seen already in cells entering for the first time in S-phase after plating. Pulse-chase experiments with 3H-thymidine (3H-TdR) indicate that vimentin containing SMC possess a higher replicative activity than vimentin plus desmin containing SMC, thus explaining the selection of vimentin containing cells during culture. Our results indicate that during culture SMC develop features similar to those observed in normal foetal SMC or in SMC present in atheromatous plaques; this model may be useful for the understanding of mechanisms leading to SMC differentiation and to atheroma formation.
TL;DR: A Xenopus laevis complementary DNA (cDNA) library prepared from messenger RNAs extracted from embryos has been screened for actin-coding sequences and it is suggested that the genes originated before the amphibia/reptile-bird divergence, more than 350 million years ago.
TL;DR: In this paper, a comparative econometric study was conducted to find that economic growth pushed urbanisation, with industrialisation being the most important factor for Europe and agricultural productivity being quite important for the European settled countries.
Abstract: This paper describes the situation from the beginning of the industrial revolution when levels of urbanisation were dependent on geography and the historical situation and when the general level of urbanisation was low, through the nineteenth century in which agricultural productivity and industrialisation determined the levels of urbanisation. This period represents a dramatic increase in the levels of urbanisation during which the present urban structures were put into place. A comparative econometric study, finds that economic growth pushed urbanisation, with industrialisation being the most important factor for Europe and agricultural productivity being quite important for the European settled countries. Other important factors are found to be, trade, total population, topography, and form of industrialisation. Railroad networks more or less extensive than normal were not found to be influential.
TL;DR: It is shown that the plasmid pSC101 is unable to be maintained in strains of E. coli carrying deletions in the genes himA and hip which specify the pleitropic heterodimeric DNA binding protein, IHF, and the proximity of the sites suggests that these three proteins may interact in generating a specific DNA structure required for initiation of pSC 101 replication.
Abstract: We have shown that the plasmid pSC101 is unable to be maintained in strains of E coli carrying deletions in the genes himA and hip which specify the pleitropic heterodimeric DNA binding protein, IHF We show that this effect is not due to a modulation of the expression of the pSC101 RepA protein, required for replication of the plasmid Inspection of the DNA sequence of the essential replication region of pSC101 reveals the presence of a site, located between the DnaA binding-site and that of RepA, which shows extensive homology with the consensus IHF binding site The proximity of the sites suggests that these three proteins, IHF, DnaA, and RepA may interact in generating a specific DNA structure required for initiation of pSC101 replication
TL;DR: A human hsp70-hGH construct was used to establish stable mouse fibroblast lines that are capable of producing and secreting hGH at high levels following heat induction: hGH is secreted at a 500-1200-fold higher rate by heat-treated than by untreated cells.
TL;DR: The results suggest that during development, under pathological conditions, and in cell culture, the expression of actin isoforms in arterial SMC depends on many factors, including the amount and translation efficiency of mRNAs, and the relative stabilities of the proteins involved.