Showing papers by "University of Geneva published in 1970"
TL;DR: The physiological manifestation of conditional lethal mutations in the genes involved in the formation of the T4 head have been re-examined in this paper, where the minimum number of head genes whose active product is needed to form the various head-related structures has been determined by examining infection by a series of double mutants.
378 citations
TL;DR: Temperature-shift experiments with ts -mutants in gene 31 demonstrate that the P23 aggregates can be dissolved by activated P31 and the dissolved P23 is normal, in that it can be used for incorporation into active phage.
368 citations
TL;DR: The technique of extracellular space tracing with horseradish peroxidase is adapted for labeling the transverse tubular system (T system) in rat heart and in atrial muscle the following two types of cells are found: those cells with a well-developed T system in which the tubular diameter is quite uniform and the orientation predominantly longitudinal and, (b) cells with no T system, but with aWell-developed L system.
Abstract: The technique of extracellular space tracing with horseradish peroxidase is adapted for labeling the transverse tubular system (T system) in rat heart. In rat ventricular muscle the T system shows extensive branching and remarkable tortuosity. The T system can only be defined operationally, since it does not display specific morphological features throughout its entire structure. Owing to branching of the T system, a sizable proportion of the apposition between the T system and L system (or closed system) occurs at the level of longitudinal branches of the T system and is not restricted to the Z line region. The regions of apposition between the T system and L system are analyzed in rat ventricular muscle and skeletal muscle (diaphragm) and compared with the intercellular tight junctions (nexuses) of heart muscle by the use of a photometric method. The over-all thickness of the nexus is significantly smaller than that of T-L junctions in both cardiac and skeletal muscles. The thickness of the membranes of the T and L systems are not significantly different in the two muscles, but the gap between both membranes is larger in the heart. In atrial muscle the following two types of cells are found: (a) those cells with a well-developed T system in which the tubular diameter is quite uniform and the orientation predominantly longitudinal and, (b) cells with no T system, but with a well-developed L system. Atrial cells possessing a T system are richly provided with specific granules and show little micropinocytotic activity, whereas cells devoid of T system show intense micropinocytotic activity and few specific granules. The possible functional implications of these findings are discussed.
204 citations
TL;DR: In this article, the generalized polylogarithms of Nielsen are studied, in particular their functional relations, and an Algol procedure for calculating 10 functions of lowest order is presented.
Abstract: The generalized polylogarithms of Nielsen are studied, in particular their functional relations. New integral expressions are obtained, and relations for function values of particular arguments are given. An Algol procedure for calculating 10 functions of lowest order is presented. The numerical values of the Chebyshev coefficients used in this procedure are tabulated. A table of the real zeros of these functions is also given.
138 citations
TL;DR: It is suggested that both the true-late and the quasi-late messengers may be active in protein synthesis at 20 minutes and that the “turn-off” of early protein synthesis may be due to control at the level of transcription rather than a mechanism involving translational control.
138 citations
TL;DR: The concentration of inorganic pyrophosphate (I.P.P.) has been determined in the plasma, urine, and synovial fluid of patients with pyroph phosphate arthropathy (chondrocalcinosis articularis or pseudogout) and metabolism in pyroph phosphate arthropathetic seems to be a local rather than generalised phenomenon.
136 citations
TL;DR: In this article, the eye of the honey bee drone is composed of approximately 8,000 photoreceptive units or ommatidia, each topped by a crystalline cone and a corneal facet.
Abstract: The eye of the honey bee drone is composed of approximately 8,000 photoreceptive units or ommatidia, each topped by a crystalline cone and a corneal facet. An ommatidium contains 9 visual or retinula cells whose processes or axons pierce a basement membrane and enter the optic lobe underlying the sensory retina. The visual cells of the ommatidium are of unequal size: six are large and three, small. In the center of the ommatidium, the visual cells bear a brush of microvilli called rhabdomere. The rhabdome is a closed-type one and formed mainly by the rhabdomeres of the six large retinula cells. The rhabdomeric microvilli probably contain the photopigment (rhodopsin), whose modification by light lead to the receptor potential in the retinula cells. The cytoplasm of the retinula cells contains various organelles including pigment granules (ommochromes), and peculiar structures called the subrhabdomeric cisternae. The cisternae, probably composed of agranular endoplasmic reticulum undergo swelling during dark adaptation and appear in frequent connection with Golgi cisternae. Three types of pigment cells are associated with each ommatidium. The crystalline cone is entirely surrounded by two corneal pigment cells. The ommatidium, including its dioptric apparatus and corneal pigment cells, is surrounded by a sleeve of about 30 elongated cells called the outer pigment cells. These extend from the base of the corneal facet to the basement membrane. Near the basement membrane the center of the ommatidium is occupied by a basal pigment cell. Open extracellular channels are present between pigment cells as well as between retinula cells. Tight junctions within the ommatidium are restricted to the contact points between the rhabdomeric microvilli. These results are discussed in view of their functional implications in the drone vision, as well as in view of the data of comparative morphology.
134 citations
TL;DR: Une nouvelle analyse de ce probleme s9impose estifiée, encore faut-il que the methode employee soit reellement capable d9obvier aux desavantages des techniques de marquage usuelles.
Abstract: Le probleme de la localisation des ebauches presomptives chez les Oiseaux est actuellement l9un des themes les plus controverses de la litterature embryologique (Graper, 1929; Wetzel, 1929, 1936; Pasteeis, 1937; Rudnick, 1944, 1948; Spratt, 1955). Une nouvelle analyse de ce probleme s9impose, encore faut-il que la methode employee soit reellement capable d9obvier aux desavantages des techniques de marquage usuelles. En effet, en particulier chez les Oiseaux, ni la technique de coloration locale au bleu de Nil, ni l9apposition de fines particules ne donne la garantie formelle que la marque se rapporte strictement au meme ensemble de cellules du debut a la fin des experiences. Nous croyons que l9emploi de la thymidine tritiee comme marqueur nucleaire peut surmonter cet obstacle. Ce radioisotope s9incorpore specifiquement dans l9ADN et ne se transmet qu9aux cellules-filles issues de cellules marquees. Cette technique a deja ete employee a plusieurs reprises chez le Poulet.
102 citations
TL;DR: In certain organs (brain, cerebellum, testis, Gasserian ganglion) histamine-type mediators are apparently unable to cause vascular leakage, suggesting that the selective response of the venules depends on an intrinsic property of the Venular wall, and not on the route whereby the mediator reaches the vessel.
Abstract: SummaryHistamine, serotonin, and bradykinin, injected intra-arterially, cause (in susceptible organs) vascular leakage predominantly from the venules. The vascular segments affected are the same as when the mediators are injected locally. This suggests that the selective response of the venules depends on an intrinsic property of the venular wall, and not on the route whereby the mediator reaches the vessel. In certain organs (brain, cerebellum, testis, Gasserian ganglion) histamine-type mediators are apparently unable to cause vascular leakage.
88 citations
TL;DR: A mutant which produces a small-headed ("petite") variant of bacteriophage T4 is described, which was nonviable upon single infection but produced progeny when two or more infected a cell.
Abstract: A mutant which produces a small-headed (“petite”) variant of bacteriophage T4 is described. The mutation (E920g) maps in a new gene (66) between genes 23 and 24. Petite phage particles composed up to 70% of the phage yield. The petite phage was nonviable upon single infection but produced progeny when two or more infected a cell. Its genome was shortened by a random deletion of about 30%, and deoxyribonucleic acid (DNA) extracted from the particles was 0.68 the length of normal T4 DNA. The reduction in DNA length was accompanied by a proportional reduction in head volume. Double mutants between E920g and head-defective mutants in gene 21 produced unusually high frequencies of spherical capsidlike structures (τ-particles).
84 citations
TL;DR: Specific regions of the phage particle were found to be associated with antibodies when they were reacted with such absorbed antisera and the implications for phage T4 assembly are discussed.
TL;DR: Amber mutants in this gene lead to incomplete peptide chains with correspondingly increased electro~horetic mobility, as predictable from the results of Sarabhai et al.
TL;DR: This article showed that early symbolic behaviour occurs only after objects have been endowed with certain physical and conventional properties and after certain kinds of creative organizational behaviour have appeared. And they showed that the beginnings of language can be studied as part of representational behaviour and may show such object and subject-oriented duality in lexical and syntactic components.
Abstract: Pre-verbal, sensory-motor intelligence progresses to where the child needs some kind of representation for further cognitive progress and where his cognitive structures make such representation possible. Observational research shows that early symbolic behaviour occurs only after objects have been endowed with certain physical and conventional properties and after certain kinds of creative organizational behaviour have appeared. The beginnings of language can be studied as part of representational behaviour and may show such object-and subject-oriented duality in lexical and syntactic components.
TL;DR: Insulin appears to regulate ATP levels by its effect on glucose entry and further metabolism and by its antilipolytic action, illustrated by the observation that insulin counteracted the depression in ATP levels induced not only by adrenaline but by caffeine as well.
TL;DR: The 5′-terminal sequence of 74 nucleotides reported here does not seem to be involved in the synthesis of phage specific proteins but is probably concerned in the replication of R17 RNA.
Abstract: The 5′-terminal sequence of 74 nucleotides reported here does not seem to be involved in the synthesis of phage specific proteins but is probably concerned in the replication of R17 RNA. It is also of comparative interest—the sequence is strikingly similar to the corresponding section of Qβ phage RNA.
TL;DR: Morphologic aspects of 318 cases of spontaneous abortion and the chromosomal constitution of 67 cases from the same material indicated the strikingly increased incidence of structural and chromosomal anomalies in younger age groups, classified according to embryonic development, not by the apparent duration of pregnancy.
TL;DR: It is concluded that the β-cytotoxic effect of streptozotocin is not immediately irreversible or that it does not affect all B-cells simultaneously; that the insulin release observed between 6 and 10 hr after the injection of strePTozotOCin occurs by way of leakage from damaged B- cells; and that streptozootoc in and alloxan differ in their mechanism of action on the pancreatic B-cell.
Abstract: SummaryFurther studies on the mode of action of streptozotocin and the prevention of its effects by nicotinamide have yielded the following results: 1. The injection of nicotinamide at varying time intervals after streptozotocin afforded partial protection against its β-cytotoxic effects, decreasing with the length of the intervals but still significant when the interval was 2 hr. 2. Manno-heptulose failed to suppress the insulin release occurring between 6 and 10 hr after the injection of streptozotocin. 3. Nicotinic acid administered by gastric tube failed to protect against the diabetogenic effect of streptozotocin. 4. Nicotinamide injected 10 min after alloxan afforded no protection against the diabetogenic effect of the latter. It is concluded (1) that the β-cytotoxic effect of streptozotocin is not immediately irreversible or that it does not affect all B-cells simultaneously; (2) that the insulin release observed between 6 and 10 hr after the injection of streptozotocin occurs by way of leakage fro...
TL;DR: A positive, statistically significant correlation was found between the concentrations of β-glucuronidase in gingival exudate and the depths of the periodontal pockets, as well as the amount of bone loss.
TL;DR: Evidence was presented that it was completely hazardous to differentiate the various pathologic states of the pulp by clinical criteria, and symptomatic classification was considered to be best suited to serve the needs of daily practice.
TL;DR: Both coronal and sagittal sections of 11 human fetuses showed that the glenoid blastema developed in close relationship with the primordial quadrate-meckelian joint to form the bony temporal joint components, including the capsular elements of the upper joint story.
Abstract: The embryologically unique origin of the temporomandibular joint from two separately (in time and space) developing blastemas was further studied in relation to temporal structures. Both coronal and sagittal sections of 11 human fetuses from the 24 mm to 72 mm crown-rump (C-R) stage showed that the glenoid blastema developed in close relationship with the primordial quadrate-meckelian joint to form the bony temporal joint components, including the capsular elements of the upper joint story. The disk developed independently of the tendon of the external pterygoid muscle as a derivative of both the condylar and the glenoid blastemas.
TL;DR: During transcription of bacteriophage T4 or T5 DNA in 0.2 M KCl, RNA polymerase is able to terminate the synthesis of RNA chains, dissociate from the DNA template and reinitiate new RNA chains on new DNA templates.
Abstract: During transcription of bacteriophage T4 or T5 DNA in 0.2 M KCl, RNA polymerase is able to terminate the synthesis of RNA chains, dissociate from the DNA template and reinitiate new RNA chains on new DNA templates.
TL;DR: In this paper, the preferential orientation of cyclopentenones has been established according to their nature and to the solvents by correlation to the vicinal and the long-range coupling constants.
Abstract: Cyclopentenones substituted in position 4, and 3, 5-cis or -trans disubstituted cyclopentenes have been studied by NMR. and by IR. spectroscopy. Cyclopentenone derivatives and cyclopentene derivatives adopt a quasi-coplanar and an envelope conformation, respectively. The preferential orientation of the substituents has been established according to their nature and to the solvents by correlation to the vicinal and the long-range coupling constants.
TL;DR: Using native T4 DNA as template, RNA polymerase can catalyze the synthesis of RNA chains at a rate of at least 20 nucleotides per second per growing RNA molecule at 37 °C, which is nearly as fast as the rate with which T4 RNA chains grow in vivo.
TL;DR: All methionine-requiring strains of Escherichia coli which have been tested show a two-fold increase in DNA content when grown in the presence of ethionine or norleucine, and breakdown of DNA appears to be a characteristic of the restriction gene products rather than of the location of these genes on plasmid or chromosomal DNA molecules.
TL;DR: In this article, it was shown that there exists a selfadjoint Hamilton operator corresponding to the interactionH 0(a)+H0(b)+∫Φb+(x)Φa(x) Φb−d3x, wherea andb denote two types of scalar particles.
Abstract: It is shown that there exists a selfadjoint Hamilton operator corresponding to the interactionH0(a)+H0(b)+∫Φb+(x)Φa(x)Φb−(x)d3x, wherea andb denote two types of scalar particles. We discuss the scattering theory of this operator.
TL;DR: In this paper, the elastic properties of six monocrystalline Pd-Rh and PdAg alloys have been measured and correlations with the magnetic susceptibility as predicted by a theoretical model have been found.
TL;DR: It is found that this is a general phenomenon, resulting from the release of nucleic acids into plant cells, in shoots dipped in a suspension of Agrobacterium tumefaciens (strain B6), virulent to plants.
Abstract: BACTERIAL RNA has been recovered from the cells of shoots dipped in a suspension of Agrobacterium tumefaciens (strain B6), virulent to plants1. We have now found that this is a general phenomenon, resulting from the release of nucleic acids into plant cells.