Showing papers by "University of Geneva published in 1977"
TL;DR: The frequencies of occurrence of amber and ochre mutations arising from the G · C → A · T transition have been compared for different mutagens, revealing several striking hotspots.
560 citations
TL;DR: Schmeissner et al. as mentioned in this paper used a fine structure deletion map to construct a combined gene-protein map, in which deletion intervals on the genetic map are correlated with known segments of the protein sequence.
486 citations
TL;DR: Ig secretion is markedly inhibited by conditions which lower intracellular calcium levels, induce partial sodium/potassium equilibration, or uncouple oxidative phosphorylation, which are accompanied by striking alterations of the ultrastructural appearance of the Golgi complex.
Abstract: Conditions influencing Ig secretion by plasma cells have been studied with suspensions of murine plasma cells and myeloma cells by determining the release of (3)H-Ig after a pulse of biosynthetic labeling with L- [4,5-(3)H]-leucine. Ig secretion is insensitive to a variety of hormones, mediators, cyclic nucleotide derivatives, extracellular calcium depletion, and agents acting on mierotubules or microfilaments; i.e., to a number of factors which are involved in the regulation of secretion by cells with a storage compartment. On the other hand, Ig secretion is markedly inhibited by conditions which (a) lower intracellular calcium levels (ionophore A 23187 in Ca(++)-free medium), (b) induce partial sodium/potassium equilibration (the ionophores monensin and nigericin and, in the case of myeloma cells, ouabain and incubation in K(+)-free medium) or (c) uncouple oxidative phosphorylation. The first two situations are accompanied by striking alterations of the ultrastructural appearance of the Golgi complex, different in each case. These ultrastructural observations, together with autoradiographic experiments after a short pulse with L-[4,5-(3)H]-leucine, have led to the following hypothesis: (a) under Ca(++) depletion (3)H-Ig passes to Golgi vesicles but these vesicles are incapable of fusion or migration and therefore accumulate in exaggerated numbers in the Golgi area; (b) under partial Na(+)/K(+) equilibration, (3)H-Ig passes to Golgi vesicles which have an exaggerated tendency to fuse with other Golgi elements, thereby generating large vacuoles which store increasing amounts of Ig; (c) under energy block, multiple membrane fission and fusion events are inhibited and there is therefore, little intracellular transport of (3)H-Ig or alteration of cell ultrastructure.
375 citations
351 citations
TL;DR: The complete results of the analysis of over 5300 independently derived nonsense mutations in the lacI gene are presented, which have been mapped and divided into specific sites to allow a detailed correlation of the physical and genetic map.
266 citations
TL;DR: In this paper, an experiment on the decay of the tau decay at the CERN proton synchrotron with spark-chamber and counter techniques was performed, and the results were compared with the theoretical predictions of current-algebra and other models.
Abstract: An experiment on the decay K/sup +/ ..-->.. ..pi../sup +/..pi../sup -/e/sup +/..nu.. was performed at the CERN proton synchrotron with spark-chamber and counter techniques. The K/sub e//sub 4/ branching ratio has been measured relative to the tau decay. The ..pi pi.. phase-shift difference delta/sup 0//sub 0/ - delta/sup 1//sub 1/ and the form factors of the hadronic current have been determined as functions of the ..pi pi.. energy. The ..pi pi.. scattering length a/sup 0//sub 0/ has been evaluated from the phase shifts with a phenomenological model. The results are compared with the theoretical predictions of current-algebra and other models.
243 citations
TL;DR: It is considered that “complete” moles constitute a “high-risk group” for malignant trophoblastic neoplasia.
224 citations
TL;DR: In this paper, resistance and ac susceptibility measurements on Tb 1.2 Mo 6 S 8, Dy 1.4 and Er 1.6 S 8 were performed and the magnetic ordering in their superconducting state at 0.9, 0.4, and 0.15 K, respectively.
174 citations
TL;DR: Co-capping of actin and tubulin with immunoglobulins (Ig) in B lymphocytes from mouse spleen provides structural evidence for cytoskeletal control of receptors.
Abstract: CYTOSKELETAL control of cell surface receptor movements1 has been suggested by several authors2,3 and is compatible with the fluid mosaic model of cell membranes4. Evidence for this hypothesis comes mostly from experiments using drugs which alter the activity of cytoskeletal components3,5,6. We report here co-capping of actin and tubulin with immunoglobulins (Ig) in B lymphocytes from mouse spleen. These findings provide structural evidence for cytoskeletal control of receptors.
170 citations
01 Jan 1977
TL;DR: In this article, a number of facts and experiments which might be of interest to those who have a practical concern with the study of thinking have been discussed, without delving into otherwise well-known theoretical considerations.
Abstract: We should like to set forth, without delving into otherwise well-known theoretical considerations, a number of facts and experiments which might be of interest to those who have a practical concern with the study of thinking. We have in mind, not only child psychologists, but also educators whose aim is to translate this psychology into effective teaching processes.
158 citations
TL;DR: A bacterial mutation affecting λ DNA replication, called groPC756, has been mapped between the thr and leu bacterial loci as mentioned in this paper, and it is shown that the mutation at the groPC locus also interferes with bacterial growth at 42°C.
Abstract: A bacterial mutation affecting λ DNA replication, called groPC756, has been mapped between the thr and leu bacterial loci. Most of the parental λ DNA does not undergo even one round of replication in this host. Lambda mutants, called π, which map in the λ P gene are able to overcome the inhibitory effect of the groPC756 mutation. It is shown that the mutation at the groPC locus also interferes with bacterial growth at 42°C. A λ-transducing phage, carrying the groPC+ allele, was isolated as a plaqueformer on groPC756 bacteria. Upon lysogenization, it restores both the gro
+ and temperature resistant phenotypes.
TL;DR: In this article, the synthesis and characteristics of copper(III) and silver (III) complexes of tellurates and periodates are described, and chemical analysis, I.R. spectra and conductimetric measurements are used to determine the formulae of these anionic complexes.
01 Jan 1977
TL;DR: In this article, the authors discuss the role of the hereditary program in cognitive development and relate it to the classical factors that have always been understood to be pertinent for cognitive development, such as the influences of the physical environment, the external experience of objects, innateness, and social transmission, the effects of social influences.
Abstract: The title “Equilibration” refers to one factor that I think is essential in cognitive development. In order to understand the role of this factor, we must relate it to the classical factors that have always been understood to be pertinent in cognitive development. There are three such classical factors: the influences of the physical environment, the external experience of objects; innateness, the hereditary program; and social transmission, the effects of social influences. It is clear that all three are important in cognitive development. I will begin by discussing them separately. But as we discuss them, I think we will see that no one of the three is sufficient in itself. Each one of them implies a fundamental factor of equilibration, upon which I shall place special emphasis.
TL;DR: In this article, a number of beispiele intramolekularer cycloadditionen of 1,3-Dienen, Nitronen, and Azomethiniminen bezeugen den praparativen Werts zur regio-and stereoselektiven Synthese anellierter sowie uberbruckter Ringsysteme.
Abstract: Zahlreiche Beispiele intramolekularer Cycloadditionen von 1,3-Dienen, Nitronen und Azomethiniminen bezeugen den praparativen Wert dieser Varianten zur regio- und stereoselektiven Synthese anellierter sowie uberbruckter Ringsysteme. Die Gemeinsamkeiten, Unterschiede und Grenzen dieser Reaktionstypen werden systematisch umrissen.
TL;DR: In this article, the authors give a criterion for the intersection of two projections in Hilbert space to be a projection of finite-dimensional range, which is applied to Schrodinger operators in L2(Rn) and to the problem of determining whether there are functions f and its Fourier transform having prescribed support.
TL;DR: This chapter discusses the circulating nucleic acids in higher organisms with a focus on bacteria, which possess several extra chromosomal factors including the F factor, R factors, and bacteriocinogenic factors, which are distinguishable by their molecular weight.
Abstract: Publisher Summary This chapter discusses the circulating nucleic acids in higher organisms. DNA is able to leave bacteria and enter other bacteria and the mechanisms and situations involved are readily understood. Bacterial DNA can move from members of one strain to those of another by means of conjugation or transduction, which does not strictly involve extracellular release of DNA. Bacteria possess several extra chromosomal factors including the F factor (the first fertility factor), R factors (antibiotic resistance transfer factors), and bacteriocinogenic factors, which are distinguishable by their molecular weight. F and R factors and some bacteriocinogens have a molecular weight of 6–140 × l0 6 , corresponding to 100 to 200 genes, while many bacteriocinogens have a molecular weight of 4–5 × 10 6 —about 15 genes. Transformation also has been achieved by providing one strain of bacteria with non-purified DNA found in the culture medium of another strain.
TL;DR: The variation in the number of copies of prophage P1 relative to two chromosomal markers when the doubling time of the host cells is modified by a change in carbon source suggests that P1 retains the ability to replicate after chromosome initiation has stopped and in the absence of essential amino acids.
Abstract: We have followed, by DNA-DNA hybridization, the variation in the number of copies of prophage P1 relative to two chromosomal markers when the doubling time of the host cells is modified by a change in carbon source. The ratio of P1/chromosome terminus undergoes a twofold decrease when the cell doubling time increases from 24 to 215 min, whereas the ratio of P1/chromosome origin increases 1.4 fold; both ratios tend towards unity at slow growth rates. This suggests that the replication of prophage P1 is not simultaneous with chromosome initiation or chromosome termination. The chromosome replication time is unaffected by the presence of P1, and remains constant over the range of doubling times studied, with a value of about 4o min. Following amino acid starvation, the P1/chromosome origin ratio increases from 0.7 to 0.9, suggesting that P1 retains the ability to replicate after chromosome initiation has stopped and in the absence of essential amino acids. The results are discussed with reference to similar studies done on F and R1.
TL;DR: Using a monospecific antibody to porcine α-actinin, the presence of this protein is demonstrated in secretory vesicle membranes from chromaffin cells of the adrenal medulla and from platelets.
Abstract: THE role of microfilaments in secretion has been much debated1–4 If secretion involves a sliding filament mechanism similar to muscle contraction5, microfilaments must attach at least transiently to vesicle membranes Indeed, there is evidence that contractile proteins are associated with secretory vesicles (chromaffin granules) of adrenal medulla6,7 Moreover, the outer (cytoplasmic) surface of secretory vesicles must provide ‘anchoring molecules’ for microfilaments In skeletal muscle, the structural protein α-actinin located in the Z-line8 serves as such an anchoring molecule An α-actinin-like protein was isolated from a variety of non-muscle cells9,10 and there is evidence that the same protein is attached to the inner (cytoplasmic) surface of the plasma membrane of non-muscle cells in association with microfilaments11–14 Using a monospecific antibody to porcine α-actinin (Fig 1) we have demonstrated the presence of this protein in secretory vesicle membranes from chromaffin cells of the adrenal medulla and from platelets
TL;DR: Two nondifferentiating variants of the FL cells were shown to have altered sensitivities to agglutination by ConA, and these changes were not observed on nonerythroid mastocytoma culture cells.
TL;DR: This synthesis shows unambigously the (2S)-configuration of natural pumiliotoxin-C, which controls to a major extent the three developing centers of chirality.
Abstract: (−)-Pumiliotoxin-C-hydrochloride, as well as its unnatural enantiomer, have been synthesized in an enantioselective manner starting from (S)- or (R)-norvaline, respectively. In the crucial cycloaddition step 11 12(cf. scheme 2) the chiral center of 11 controls to a major extent the three developing centers of chirality. This synthesis shows unambigously the (2S)-configuration of natural pumiliotoxin-C.
TL;DR: Much more than a purely intellectual exercise, the studies described have opened new possibilities for the prevention and treatment of distressing situations such as burn wound contractures, tracheal stenosis, periprosthetic capsular retraction, and others.
TL;DR: The gene order identified on λrifd18 is probably identical to that on the Escherichia coli chromosome, except that the identity of the tRNA gene in the rRNA transcription unit is ambiguous.
TL;DR: Mapping techniques have been developed which allow the construction of a detailed fine structure map of the lacI gene, which allows the rapid positioning of missense mutations and the accurate estimation of the location of the corresponding altered amino acid in the protein.
TL;DR: A simple marker rescue technique is described for the genetic identification of the cloned T4 fragments.
Abstract: Bacteriophage T4 DNA containing cytosine has been obtained from cells infected with phage mutant in genes 42, 56, denA and denB This DNA can be cut by a number of restriction endonucleases Fragments obtained by digestion of this DNA with EcoRI have been cloned using the vector plasmid pCR1 Clones containing T4 DNA were identified by hybridization with radioactive early and late T4 RNA A simple marker rescue technique is described for the genetic identification of the cloned T4 fragments Some of the T4-hybrid plasmids which contain entire T4 genes can complement temperature sensitive and amber mutants of T4
TL;DR: Results indicate that TBTO interfered with the process of respiration and a ‘safe level’ (0.1 μg/1) is proposed for schistosomiasis control.
Abstract: In acute toxicity tests based on the loss of positive rheotaxis, the relationship between exposure time and bis (tri-n-butyltin) oxide concentration was determined for Salmo gairdneri and Tilapia rendalli. This relationship may be represented by two superimposed rectangular hyperbolas (X-d) (Y-b)=c corresponding to two poisoning mechanisms. The 24-h EC50 is 30.8 μg/1 for trout and 53.2 μg/1 for T. rendalli. A histopathological study on S. gairdneri shows concentrations from 5.85 to 0.0117 mg TBTO/1 resulted in damage to the gill epithelium. At low concentrations a degeneration of the cornea and damage to the epithelial cells of bile ducts were also observed. Prior to a loss of positive rheotaxis and with concentrations from 0.023 to 1.17mg/l, the packed cell volume, the haemoglobin concentration and erythrocyte count increased. Determination of the mean cell volume showed swelling took place at 1.17 mg/1 but shrinkage was observed at 0.053 mg/1. These results indicate that TBTO interfered with the process of respiration. A ‘safe level’ (0.1 μg/1) is proposed for schistosomiasis control.
TL;DR: In this article, the properties of the series Mo 6 X 8− x Y x (X = S, Se, Te; Y = Br, I) having the hexagonal rhombohedral structure of the PbMo 6 S 8 type were studied.
TL;DR: Intracellular recordings were made from the outer segments of rods in the isolated, superfused retina of Bufo marinus to measure changes of membrane voltage and some concomitant changes of input resistance in response to light, membrane polarization and iontophoretic injections.
Abstract: 1. Intracellular recordings were made from the outer segments of rods in the isolated, superfused retina of Bufo marinus. Cells were impaled under observation with a compound microscope fitted with an infra-red image converter. Changes of membrane voltage and some concomitant changes of input resistance were measured in response to light, membrane polarization and iontophoretic injections.2. By means of a double barrel micropipette, charge was passed into a rod from a micropipette barrel that contained Ca(2+) while no net current crossed the plasma membrane. In about half the cells, immediately after the injection, a hyperpolarization was observed that decayed with a time course similar to the decay of the receptor potential.3. Membrane hyperpolarization also occurred after a depolarizing current stopped flowing into a rod through a single barrel pipette that contained only K-acetate. This hyperpolarization was accompanied by an increase of membrane conductance. The reversal potential for the conductance-increase was between the voltage in the dark and the voltage in the absence of [Na(+)](out). A larger hyperpolarization became evident after an equal depolarizing current stopped flowing into a rod through a pipette that also contained Ca(2+); this larger after-hyperpolarization was due to both the cessation of depolarizing current and the injection of Ca(2+).4. A depolarization of 10-20 mV that lasted 2-60 sec became evident after hyperpolarizing current stopped flowing into a rod through a single-barrel pipette filled with K-EGTA. During the after-depolarization, the responses to small, dim spots of light were attenuated. No depolarization was observed after passing hyperpolarizing currents into rods through pipettes that contained either acetate(-), SO(2-) (4) or MOPS(-).5. These results show that sequestration of [Ca(2+)](in) depolarizes the plasma membrane and that an increase in [Ca(2+)](in) hyperpolarizes the membrane mimicking the later part of the receptor potential. These findings support the hypothesis of Yoshikami & Hagins (1971) that Ca(2+) is an intracellular messenger for excitation in vertebrate rods.
TL;DR: This chapter summarizes the major advances in the understanding of several aspects of reparative processes made in the last few years.
Abstract: Publisher Summary This chapter summarizes the major advances in the understanding of several aspects of reparative processes made in the last few years. Humans, as well as other vertebrates, do not possess a great power of cell or organ regeneration when compared with lower species, and repair of a loss of tissue is essentially made by the synthesis of connective tissue which abrogates the volume discontinuities and keeps together the margins of the remaining parenchymas. Only some tissues, such as epidermis, are capable of regenerating over the scar and reconstituting the continuity lost with the wound. In general, the healing of a wound consists of two interconnected phenomena: (1) synthesis and/or regeneration of tissues which replace the damaged ones, and (2) remodeling of these tissues to restore the form of the body. The relative importance of these phenomena may vary. In cutaneous linear wounds or in wounds of areas firmly adherent to deeper planes, the reduction in spatial discontinuity is due to the local growth of granulation tissue and epithelium, whereas in large wounds of mobile areas of the skin, or in ischemic lesions of the myocardium, the reduction in spatial discontinuity is mostly due to wound contraction. The reparative events are generally preceded by hemostatic and inflammatory phenomena which may in turn influence the final result of wound healing.
TL;DR: New chimeric Escherichia coli plasmids containing α or β globin gene sequences of the mouse were constructed, which contain at least 90% of the globin mRNA sequence and therefore contain the entire translated sequence of the Globin genes.
TL;DR: A core sample from the Western Basin of Lake Erie indicated that ΣDDT, HEOD and PCB began to accumulate in sediments in 1958, 1953, and 1956, which appeared to indicate a lag period of 2–5 years after wide-spread use occurred.