Showing papers by "Hungarian Academy of Sciences published in 1977"
TL;DR: A circular genetic map of the R. meliloti 41 chromosome is presented and a new approach in the evaluation of conjugational mapping data which may be applicable to other Gram-negative bacteria is described.
Abstract: GENETIC studies on symbiotic nitrogen-fixing rhizobia are greatly hampered by the lack of an efficient system for genetic mapping in rhizobia. Although there have been reports on transformation1–3 and transduction4 in nodulating rhizobia as well as conjugation5 in a non-nodulating strain of Rhizobium lupini, the genetic map of a nodulating and nitrogen-fixing Rhizobium strain has not been established yet. Plasmids of the P-1 incompatibility group have a remarkably wide host range and can be transferred to many Rhizobium species6,7. Some of these plasmids can promote chromosome transfer in Pseudomonas aeruginosa strain PAT but show little chromosome donor ability (Cda) in strain PAO8,9. Recently a variant (R68.45) of the P group plasmid R68, with high Cda property in strain PAO, was isolated by Haas and Holloway10. Plasmid R68.45, unlike most of the sex factors, promotes chromosome transfer for a range of chromosomal genes in Rhodopseudomonas, P. putida, Escherichia coil (B. W. Holloway, personal communication) and in Rhizobium leguminosarum11. We have found that this plasmid can promote chromosome transfer also in Rhizobium meliloti and can be used for mapping of the chromosome. We present here a circular genetic map of the R. meliloti 41 chromosome and describe a new approach in the evaluation of conjugational mapping data which may be applicable to other Gram-negative bacteria.
146 citations
TL;DR: Evidence is presented strongly suggesting that the actual number of rRNA gene sets is seven in E. coli K12, rather than the currently estimated six.
139 citations
TL;DR: In this article, the problem of noncollinear second harmonic generation (NSHG) of short, spatially limited light pulses in uni-axial nonlinear crystals has been solved based on an analysis of the obtained solution.
121 citations
TL;DR: In this paper, the authors classified and reviewed 334 carbocationic copolymer pairs in terms of the extended Kelen-Tudos method and found that only 49 (14.7%) were found to contain sufficiently accurate and reliable data to satisfy acceptance in class I, while 40 (12%) were accepted only in class II, and 26 (7.8%) were placed in class III, i.e., systems that exhibit unacceptable data scatter in the η versus ξ plot.
Abstract: Increased insight into the mechanism of carbocationic copolymerization has been achieved by classifying and reviewing in detail 334 monomer pairs in terms of the extended Kelen-Tudos method. The reactivity ratios (r values) of essentially all published olefin–olefin, olefin–vinyl ether, vinyl ether-vinyl ether, and some miscellaneous systems have been reexamined and classified. Of the systems reviewed, only 121 (36.2%) contained sufficiently detailed information for comprehensive reevaluation and classification. Of these, only 49 (14.7%) were found to contain sufficiently accurate and reliable data to satisfy acceptance in class I, i.e., systems which are adequately described by the conventional copolymer composition equation, while 40 (12%) were accepted only in class I(!), i.e., systems for which the available data are somewhat less reliable than for class I and some caution is in order when employing r values for quantitative purposes. Six (1.8%) monomer pairs were judged to belong to class II, i.e., systems for which the approximations implicit in the conventional copolymer composition equation do not hold and published r values are probably erroneous and misleading. Finally, 26 (7.8%) monomer pairs were placed in class III, i.e., systems that exhibit unacceptable data scatter in the η versus ξ plot and published r values are meaningless. In some instances, even the existence of true copolymers is questioned.
115 citations
TL;DR: In this article, the depth of hydrogenolysis and the formation of saturated products of 3-methylpentane (3MP) and methylcyclopentane (MCP) for eleven different metals were compared.
Abstract: GENERAL knowledge about the factors governing the catalytic activity of various metals in different skeletal reactions of hydrocarbons is rather limited. Comparative studies are reported here on the depth of hydrogenolysis and the formation of saturated products of 3-methylpentane (3MP) and methylcyclopentane (MCP) for eleven different metals. We have found that isomerisation, C5 ring closure and opening activity of Rh, Pd, Ir and Pt can be correlated with their f.c.c. structure, and their atomic dimensions being in a narrow range. These four metals promote single hydrogenolysis whereas multiple fragmentation is the only reaction observed over Co, Ni, Cu, Ru, Ag, Re, Os. Hydrogenolysis activity and pattern are less characteristic for each group.
110 citations
TL;DR: It is proposed that more than one mode of binding is possible between the isomers and the three different active sites of hydroxycitrate.
104 citations
TL;DR: The cytological analysis of parasexual hybrids revealed that the chromosome number ranged from 34 to 54, and the most frequent chromosome number was 2n = 36.
Abstract: Protoplasts isolated from cultured cells of albino carrot (Daucus carota) and normal green D. capillifolius were fused by polyethylene glycol. Selection of somatic hybrid plants was based on the restoration of photosynthetic function in hybrids. Green plantlets selected from embryo cultures were characterized on the basis of leaf morphology. The interspecific protoplast fusion resulted in green plants with leaves which were intermediate between those of the parents. The somatic hybrids between orange rooted carrot variety and D. capillifolius with long white roots produced long, white and fleshy roots. The cytological analysis of parasexual hybrids revealed that the chromosome number ranged from 34 to 54. The most frequent chromosome number was 2n = 36. Hybrids were also found with 34 and 35 chromosomes. The somatic hybrid showed the same isoenzyme pattern of leaf peroxidase as D. carota.
102 citations
101 citations
TL;DR: Denote by K1 = K1(U)(i = 0,1,…,n) the number of i-element members of an order idealU.
96 citations
TL;DR: It is indicated that ammonia is assimilated via the GS/GOGAT pathway in free-living R. meliloti and bacterial GOGAT is not important in symbiosis.
Abstract: The enzymes involved in ammonia assimilation by Rhizobium meliloti 4l and their role in the regulation of nitrogen metabolism were studied. Glutamine synthetase (GS) and glutamate synthase (GOGAT) were present at relatively high levels in cells grown in media containing either low or high concentrations of ammonia. NADP-linked glutamate dehydrogenase could not be detected. GOGAT and GS mutants were isolated and characterised. A mutant lacking GOGAT activity did not grow even on high concentrations of ammonia, it was a glutamate auxotroph and was effective in symbiotic nitrogen fixation. The GS and assimilatory nitrate reductase activities of this mutant were not repressible by ammonia but still repressible by casamino acids. A mutant with low GS activity required glutamine for optimal growth. It was ineffective and its nitrate reductase was not inducible. These findings indicate that ammonia is assimilated via the GS/GOGAT pathway in free-living R. meliloti and bacterial GOGAT is not important in symbiosis. Furthermore, GS is suggested to be a controlling element in the nitrogen metabolism of R. meliloti.
89 citations
TL;DR: A technique is presented to determine the region of achievable rates for some source and channel networks and this technique is applied to the solution of a source:network problem.
Abstract: A technique is presented to determine the region of achievable rates for some source and channel networks. This technique is applied to the solution of a source:network problem that seems to be the simplest illustration of a new typical difficulty in coding for source networks: namely, when the same encoding of a source is required to meet the conflicting demands of 1) supplying side-information to the decoder of another source, and 2) providing direct-information to its own decoder in company with other side-information.
TL;DR: In this paper, it was proved that r n (x) is a good estimation of r(x) and αn = n-α(0 < α < 1) and K(.) is a suitable ensity function.
Abstract: Let (Xi,Yi), (X2,Y2),… be independent, identically distributed pairs of r.v.'s such that .Let r0(x)≡0 and where αn=n-α(0<α<1) and K(.) is a suitable ensity function. Theorems are proved stating that r n (x) is a good estimation of r(x).
TL;DR: In this article, the first neighbor model was fitted to the experimental structure function and to the structure function calculated from the radial pair correlation functions of the simulation of a system consisting of 200 water molecules, 8 sodium and 8 chloride ions, and compared with x-ray investigations of a 2 molal NaCl solution through the structure functions.
Abstract: The molecular dynamics simulation has been improved by introducing the Ewald summation for ion-ion interactions. On the basis of the Pauling radii new Lennard-Jones parameters have been derived for the halide ions. The results of a simulation of a system consisting of 200 water molecules, 8 sodium and 8 chloride ions are compared with x-ray investigations of a 2 molal NaCl solution through the structure functions. The first neighbor model commonly used in the x-ray analysis of multicomponent liquids is fitted to the experimental structure function and to the structure function calculated from the radial pair correlation functions of the simulation. The parameters of the two fits and the radial pair correlation functions calculated from the fitted first neighbor model are compared. On the basis of this comparison the usefulness and the limitations of the first neighbor model are discussed
TL;DR: In this paper, a survey of some actual problems of the track processing methods available at this time for plastics is presented, and some properties of a promising new track processing method based on graft polymerization are discussed.
TL;DR: In this paper, the CIE recommended the adoption of two new color spaces: CIELUV and CIELAB, and the first of these is only a minor modification of CIE 1964 color space, and includes a new u'v' chromaticity diagram replacing the 1960 uv diagram.
Abstract: In 1976 the CIE recommended the adoption of two new color spaces: CIELUVand CIELAB. The first of these is only a minor modification of the CIE 1964 color space, and includes a new u'v' chromaticity diagram replacing the 1960 uv diagram. Correlated color temperature can be calculated using the new diagram, leading to somewhat different results than those calculated according to the CIE 1960 uv diagram. This paper shows the differences for the correlated color temperatures of different phases of daylight.
TL;DR: RNA with a sedimentation coefficient of 64S was isolated from infectious bronchitis virus, an avian coronavirus that contained a polyadenylic acid tract and was found to be infectious.
Abstract: RNA with a sedimentation coefficient of 64S was isolated from infectious bronchitis virus, an avian coronavirus. The SNA contained a polyadenylic acid tract and was found to be infectious.
TL;DR: In this article, the influence of doubly ionized TCNQ in the samples is discussed and D+ impurities compensating the excess charge is discussed, which is correlated with the presence of doubley ionized QN(TCNQ)2 in the sample.
Abstract: Variations in the conductivity of QN(TCNQ)2 depending on sample preparation are correlated with the presence of doubly ionised TCNQ in the samples. Increasing TCNQ2- concentration results in decreasing conductivity and increasing activation energy. The influence of D+ impurities compensating the excess charge is discussed.
TL;DR: In this article, the 13 C-NMR spectra of nine naturally occurring C-C linked biflavanoids have been assigned and the level of oxidation of the ring C can be readily determined by a consideration of the chemical shift value of the carbonyl resonances.
TL;DR: The genome of the coronaviruses is a single continuous chain of about 23,000 mononucleotides that is of messenger polarity that was confirmed by RNase T1 fingerprinting and indicated that IBV RNA is haploid.
Abstract: Techniques are described for the growth and rapid purification of the avian coronavirus infectious bronchitis virus (IBV). Purified IBV has a sedimentation coefficient of 320S and a buoyant density of 1.22 g/ml in sucrose-deuterium oxide equilibrium gradients. IBV RNA extracted by proteinase K in the presence of sodium dodecyl sulfate and further purified by phenol extraction and gradient centrifugation is single stranded and has a sedimentation coefficient of 64S, as determined by isokinetic gradient centrifugation. Analysis on sucrose gradients under both aqueous and denaturing conditions together with agarose gel electrophoresis in the presence of the chaotropic agent methylmercuric hydroxide gave a value of 8 X 10(6) for the moleclar weight of IBV RNA. This value was confirmed by RNase T1 fingerprinting, which also indicated that IBV RNA is haploid. No evidence was found of subunit structure in IBV RNA. From these results together with the recently reported observation that IBV RNA is infectious and contains a tract of polyadenylic acid (Lomniczi, J. Gen. Virol., in press), we conclude that the genome of the coronaviruses is a single continuous chain of about 23,000 mononucleotides that is of messenger polarity.
TL;DR: In this paper, the structure of amorphous silicon and amorphem silizium prepared by glow discharge technique is investigated using phase contrast electron microscopy and electron diffraction, and it is concluded that there is a higher degree of local order in glow discharge Si.
Abstract: The structure of evaporated amorphous silicon and amorphous silicon prepared by glow discharge technique is investigated using phase contrast electron microscopy and electron diffraction. While evaporated Si shows a supernetwork of density fluctuations commonly observed in evaporated amorphous tetrahedrally bonded semiconductors, glow discharge Si shows no such quasiperiodic heterogeneous density fluctuation. Electron diffraction patterns are obtained using a translation detector, which directly measures the electron intensity in the image plane of the electron microscope. From the resulting RDF it is concluded, that there is a higher degree of local order in glow discharge Si.
Mit Hilfe von Phasenkontrast-Elektronenmikroskopie und Elektronenbeugung wird die Struktur von aufgedampftem amorphem Silizium und von amorphem Silizium, das mit der “glow discharge” -Technik gewonnen wurde, untersucht. Wahrend aufgedampftes Si das Supernetzwerk von Dichtefluktuationen zeigt, wie es ublicherweise in aufgedampften tetraedrisch gebundenen amorphen Halbleitern gefunden wird, hat “glow discharge”-Si keine solche heterogene, quasiperiodische Dichtefluktuation. Mit Hilfe eines Translationsdetektors, der die Elektronenintensitat direkt in der Bildebene des Elektronenmikroskops mist, wird das Elektronenbeugungsspektrum aufgenommen. Aus der resultierenden RDF wird geschlossen, das der Grad der lokalen Ordnung in “glow discharge”-Si groser ist.
TL;DR: It is concluded that the stimulation of (Na+‐K+)‐activated ATP‐ase in the membrane inhibits the release of transmitter, and under physiological condition Ca‐fluxes and the subsequent inhibition of membrane ATP‐ enzyme may be involved in triggering therelease of transmitter.
Abstract: 1. The release of acetylcholine (ACh) from Auerbach's plexus of guinea-pig ileum has been measured in eserinized Krebs solution using longitudinal muscle strip preparations. 2. Removal of the external K ions enhanced both the resting and stimulated release of ACh from the plexus. This effect was not affected by tetrodotoxin. 3. On readmission of K+ to tissues which had been suspended in K-free Krebs solution the release of ACh was promptly reduced in both stimulated and unstimulated tissues. The extent of the reduction of ACh release depended on the exposure time to K-free solution, the recovery being delayed by longer exposure. 4. The ACh releasing effect of (1,1-dimethyl-4-phenyl-piperazinium iodide (DMPP) was completely inhibited by the readmission of K ions to tissue which had been kept in K-free Krebs solution. 5. Rb+ substitution for K+ produced no change in ACh release and addition of 5-9 mM-Rb after K removal reduced the release of ACh as K did readmission. When the K ions were substituted by Cs+, both the resting and stimulated release were enhanced. The amount of ACh released by a stimulus was enhanced both at low and high frequency of sustained stimulation. 6. Removal of the external K ions increased the release of tritiated noradrenaline (NA), from isolated rat iris; however, when K+ (5-9 mM) was readmitted the release was reduced even below the control value. 7. It is concluded that the stimulation of (Na+-K+)-activated ATP-ase in the membrane inhibits the release of transmitter, and under physiological condition Ca-fluxes and the subsequent inhibition of membrane ATP-ase may be involved in triggering the release of transmitter.
TL;DR: In this article, X-ray, electron and neutron-diffraction data have been used for the separation of the g oo(r), g od(r) and g dd (r) atom-atom pair-correlation functions of liquid D2O.
Abstract: X-ray, electron and neutron-diffraction data have been used for the separation of the g oo(r), g od(r) and g dd(r) atom-atom pair-correlation functions of liquid D2O. The experimental pair-correlat...
TL;DR: On the basis of ESR spectra, humic substances are believed to be hydroquinone type polymer radicals with considerable cation exchange and redox capacity as discussed by the authors, and all 3 d -transition metal humates appear to be ionic high spin complexes.
TL;DR: In this paper, the problems and results on combinatorial number theory are discussed and a discussion of number theoretic problems that are of combinatorially nature is presented, which is a branch of pure mathematics devoted primarily to the study of the integers.
Abstract: Publisher Summary This chapter discusses the problems and results on combinatorial number theory. It discusses number theoretic problems that are of combinatorial nature. Number theory is a branch of pure mathematics devoted primarily to the study of the integers. Number theorists study prime numbers along with the properties of objects made out of integers. Integers can be considered either in themselves or as solutions to equations. Questions in number theory are often understood through the study of analytical objects that encode properties of the integers, primes or other number-theoretic objects in some fashion. Real numbers can also be studied in relation to rational numbers.
TL;DR: It is shown that the bleached BR under blue-light excitation operates as a proton-sink for protons produced and pumped through the membrane by the photo-excited BR, which seems to be of fundamental importance in the cellular regulatory mechanism of Halobacteria.
TL;DR: Delayed‐type hypersensitivity (DTH) to 2‐phenyl‐4‐ethoxymethylene‐5‐oxazolone (oxAZolone) was found to be under multigenic control in inbred, H‐2 congenic and intra‐H‐2 recombinant strains of mice.
Abstract: Delayed-type hypersensitivity (DTH) to 2-phenyl-4-ethoxymethylene-5-oxazolone (oxazolone) was found to be under multigenic control in inbred, H-2 congenic and intra-H-2 recombinant strains of mice. A high response was associated with haplotypes H-2d,a,k and low response with haplotype H-2b. DTH to oxazolone was high or intermediate in different F1 hybrids of high and low responder mice. In F2 and backcross generations a higher response was associated with the "dd", than with "bb" phenotype, while intermediate response was found in the heterozygote "db" mice. A study of H-2 recombinant strains suggests that a gene controlling the DTH response maps in the I-B subregion of the H-2 complex. The response was significantly modified by gene(s) which are not linked to the H-2 complex and have not been mapped. Since congenitally athymic nude (nu/nu) mice did not respond to oxazolone, this contact sensitivity is belived to be a T cell-dependent immune response.
TL;DR: After total deafferentation of the medial hypothalamus in the rat, noradrenaline concentration in the nucleus arcuatus and the eminentia mediana diminished to one-third and the same decrease resulted also from partial (anterolateral) deAfferentation, which indicates that nor adrenaline containing axons enter the medial basal hypothalamus laterally from the medial forebrain bundle.
TL;DR: In this paper, electron-diffraction measurements for heavy and light water at 5°C were presented and analyzed in terms of atom-atom pair-correlation functions and molecular correlation functions.
Abstract: Electron-diffraction measurements for heavy and light water at 5°C are presented and analysed in terms of atom-atom pair-correlation functions and molecular correlation functions.