Showing papers by "Hungarian Academy of Sciences published in 1986"
TL;DR: It was found that the gene 5 promoter is active in a tissue-specific fashion whereas this is not the case for the NOS promoter, providing the first documented instance of a gene derived from a procaryotic host the expression of which is apparently regulated by plant growth factors.
Abstract: A “plant gene vector cassette” to be used in combination with various Escherichia coli gene-cloning vectors was constructed. This cassette contains a replication and mobilization unit which allows it to be maintained and to be transferred back and forth between E. coli and Agrobacterium tumefaciens hosts provided these hosts contain plasmid RK2 replication and mobilization helper functions. The cassette also harbors a transferable DNA unit with plant selectable marker genes and cloning sites which can be combined with different bacterial replicons, thus facilitating the reisolation of transferred DNA from transformed plants in E. coli. The vector cassette contains two different promoters derived from the T-DNA-encoded genes 5 and nopaline synthase (NOS). By comparing the levels of expression of the marker enzymes linked to each of these promoter sequences, it was found that the gene 5 promoter is active in a tissue-specific fashion whereas this is not the case for the NOS promoter. This observation provides the first documented instance of a gene derived from a procaryotic host the expression of which is apparently regulated by plant growth factors.
2,064 citations
TL;DR: The microwave extraction method was more effective than the traditional Soxhlet or shake-flask extraction methods and suitable for fast extractions of large sample series.
484 citations
TL;DR: In this paper, relative indicators of chemistry research in 25 countries are presented as an illustrative example, and the use of relational charts in displaying the indicators broadens the scope of such assessments.
Abstract: Cross-field comparison ofscientometric indicators
1 is severely hindered by the differences in publication and citation habits of science fields. However, relating publication and citation indicators to proper field-specific reference standards,relative indicators can be built, which may prove rather useful in the comparative assessment of scientists, groups, institutions or countries. The use ofrelational charts in displaying the indicators broadens the scope of such assessments. Relative indicators of chemistry research in 25 countries are presented as an illustrative example.
462 citations
TL;DR: An upper bound for the number of points of local nonconvexity in the union ofm Minkowski sums of planar convex sets is obtained and can be applied to planning a collision-free translational motion of a convex polygonB amidst several polygonal obstacles.
Abstract: Let ?1,..., ?m bem simple Jordan curves in the plane, and letK1,...,Km be their respective interior regions. It is shown that if each pair of curves ?i, ?j,i ?j, intersect one another in at most two points, then the boundary ofK=?i=1mKi contains at most max(2,6m ? 12) intersection points of the curves?1, and this bound cannot be improved. As a corollary, we obtain a similar upper bound for the number of points of local nonconvexity in the union ofm Minkowski sums of planar convex sets. Following a basic approach suggested by Lozano Perez and Wesley, this can be applied to planning a collision-free translational motion of a convex polygonB amidst several (convex) polygonal obstaclesA1,...,Am. Assuming that the number of corners ofB is fixed, the algorithm presented here runs in timeO (n log2n), wheren is the total number of corners of theAi's.
422 citations
TL;DR: The definition and properties of the bond order and valence indices calculated from ab initio wave functions are summarized in this paper, and their physical interpretation relationship to the exchange effects in bonding and generalization to correlated wave functions is also discussed.
Abstract: The definition and properties of the bond order and valence indices calculated from ab initio wave functions are summarized. Their physical interpretation relationships to the exchange effects in bonding and generalization to correlated wave functions are also discussed. Some examples with typical bond order and valence values are shown.
398 citations
358 citations
TL;DR: Lethr(n) denote the maximum number of edges in anr-uniform hypergraph onn vertices and in which the union of any three edges has size greater than 3r − 3.
Abstract: LetH be a fixed graph of chromatic numberr. It is shown that the number of graphs onn vertices and not containingH as a subgraph is $$2^{(\begin{array}{*{20}c} n \\ 2 \\ \end{array} )(1 - \frac{1}{{r - 1}} + o(1))} $$ . Leth r (n) denote the maximum number of edges in anr-uniform hypergraph onn vertices and in which the union of any three edges has size greater than 3r ? 3. It is shown thath r (n) =o(n 2) although for every fixedc < 2 one has lim n?? h r (n)/n c = ?.
321 citations
TL;DR: Here an information-theoretic proof of the blowing-up lemma, generalizing it to continuous alphabets, is given.
Abstract: The blowing-up lemma says that if the probability with respect to a product measure of a set A\subseteq {\cal X}^{n} ({\cal X} finite, n large) is not exponentially small, then its l_{n} -neighborhood has probability almost one for some l_{n} = O(n) . Here an information-theoretic proof of the blowing-up lemma, generalizing it to continuous alphabets, is given.
216 citations
TL;DR: The involvement of this sequence in the expression of nodulation functions is demonstrated, which suggests that these extended promoter regions may have a role in the coordinated regulation of nodulations genes.
Abstract: A 47-base-pair (bp) conserved sequence in the 5′-flanking regions of three transcriptional units coding for nodulation functions (nodABC, nodEFG, and nodH) has been identified in Rhizobium meliloti strain 41. The conserved region contains subsequences of 7 bp, 5 bp, and 25 bp. The conserved 25-bp sequence was synthesized and used as a hybridization probe; three additional copies of the sequence were identified in R. meliloti 41; all three were localized in the 135-kb nod/nif region of the symbiotic megaplasmid. Nucleotide sequence analysis of the six regions revealed that all contained the 47-bp conserved sequence but, with one exception, adjacent DNA regions did not have long conserved DNA stretches. The position of the 47-bp region was about 200-240 bp upstream of the translational start codons of the three nod genes. This conserved sequence is present in several other Rhizobium species and located adjacent to nod genes. We have demonstrated the involvement of this sequence in the expression of nodulation functions, which suggests that these extended promoter regions may have a role in the coordinated regulation of nodulation genes.
207 citations
TL;DR: The first in situ observations and a description of the large-scale behavior of comet Halley's plasma environment were presented in this paper. But the results of the experiments were limited.
Abstract: We present the first in situ observations and a description of the large-scale behaviour of comet Halley's plasma environment. The PLASMAG-1 experiment, carried aboard the spacecraft Vega 1 and Vega 2, had the following aims: (1) to study the change of plasma parameters and distributions as a function of distance from the nucleus; (2) to investigate the existence and structure of the cometary bow shock; (3) to determine the change in chemical composition of the heavily mass-loaded plasma as the spacecraft approached the comet; and (4) to measure the neutral gas distribution along the spacecraft trajectory. We observe a discontinuity (the ‘cometopause’) between the solar-wind-controlled cometosheath and heavy-ion mantle and the magnetized cometary plasma region. From the measured neutral gas density distribution we estimate a total gas production rate of 1.3×1030 molecules s−1.
198 citations
TL;DR: In R. meliloti, four nodulation genes determining plant host-range specificity and have been identified hsnABC and D, which determine plant-specific infection through root hairs: hsnD is required for host-specific root hair curling and nodule initiation while the hsn ABC genes control infection thread growth from the root hairs.
TL;DR: In this paper, the authors investigated the hydrogenation of CO2 over Pd supported by A12O3, TiO2, SiO2 and MgO in a flow technique at 1 and at 9.5 atm.
TL;DR: The minimal number of edges in F-saturated graphs is examined and general estimations are given and the structure of minimal graphs is described for some special forbidden graphs (stars, paths, m pairwise disjoint edges).
Abstract: Let F = {F1,…} be a given class of forbidden graphs. A graph G is called F-saturated if no Fi ∈ F is a subgraph of G but the addition of an arbitrary new edge gives a forbidden subgraph. In this paper the minimal number of edges in F-saturated graphs is examined. General estimations are given and the structure of minimal graphs is described for some special forbidden graphs (stars, paths, m pairwise disjoint edges).
TL;DR: In this paper, the authors summarized the present, pre-encounter understanding of the physical and chemical processes controlling the inner (r less than 1000 km) region of cometary atmospheres.
Abstract: This paper summarizes the present, preencounter understanding of the physical and chemical processes controlling the inner (r less than 1000 km) region of cometary atmospheres. Special emphasis was attached to compiling a self-consistent set of governing equations. This review is aimed at readers who want to understand the present status of the mantle and coma regions and/or who want to develop new, next generation models which will be needed as the large volume of new observational data will become available in the near future.
TL;DR: A new bibliometric indicator, “relative subfield impact”, is introduced which compares the number of citations received by papers of a research unit to the average sub field impact factor.
Abstract: Some bibliometric methods for the assessment of the publication activity of research units are discussed on the basis of impact factors and citations of papers. “Average subfield impact factor” of periodicals representing subfields in chemistry is suggested. This indicator characterizes the average citedness of a paper in a given subfield. Comparing the total sum of impact factors of corresponding periodicals divided by the number of papers published by a research team to the average subfield impact factor a “publication strategy” indicator can be derived. A new bibliometric indicator, “relative subfield impact”, is introduced which compares the number of citations received by papers of a research unit to the average subfield impact factor.
TL;DR: In inside-out red cell membrane vesicles active calcium transport and the formation of the enzyme-phosphate complex (EP) of the calcium pump were simultaneously investigated and the effects of a limited proteolytic digestion examined, suggesting a probable molecular arrangement for the functional parts of the red cell membranes calcium pump.
TL;DR: DNA-DNA hybridization analysis showed the presence of the structural gene of the kanamycin resistant determinant in total DNA isolated from several independent transformants and clearly demonstrate the transfer, stable maintenance and functional expression of the Kanamycin resistance marker in Medicago varia cells which retain their morphogenic property.
Abstract: Shoot segments of Medicago varia genotype A2 were co-cultivated with Agrobacterium tumefaciens strain bo42 carrying pGA471, a plasmid coding for the kanamycin resistant determinant as transferable positive selection marker in plant cells (An et al., 1985). Resistant plants were regenerated at high frequency from green calli developed on inoculated stem cuttings under kanamycin selection. DNA-DNA hybridization analysis showed the presence of the structural gene of the kanamycin resistant determinant in total DNA isolated from several independent transformants. All data presented clearly demonstrate the transfer, stable maintenance and functional expression of the kanamycin resistance marker in Medicago varia cells which retain their morphogenic property.
01 Sep 1986
TL;DR: This sexual cybridization method offers a simple way to transfer chloroplasts solely, a goal not accessible by protoplast fusion.
Abstract: Transmission of paternal chloroplasts was observed in Nicotiana, considered to inherit organelles in a strictly maternal way. Plants carrying streptomycin resistant plastids were used as pollen donors. Cell lines with paternal plastids in the offspring were selected as green (resistant) sectors on calli induced from the seedlings on streptomycin-containing media. The presence of paternal plastids in the regenerated plants was confirmed by restriction analysis. In the Nicotiana plumbaginifolia ♀xN. plumbaginifolia Np(SR1)3 ♂ and the N. plumbaginifolia Np(gos)29 ♀xN. tabacum SR1 ♂ crosses 2.5% and 0.07% of the offspring were found to contain paternal (tabacum) plastids, respectively. These plants, however, carried maternal mitochondria exclusively. This sexual cybridization method offers a simple way to transfer chloroplasts solely, a goal not accessible by protoplast fusion.
TL;DR: It is shown here that CIT2 encodes a nonmitochondrial form of citrate synthase, which is a possible explanation for why the C IT2 product, unlike the CIT1 product, fails to be imported into mitochondria.
Abstract: Saccharomyces cerevisiae contains two genes, CIT1 and CIT2, encoding functional citrate synthase (K.-S. Kim, M. S. Rosenkrantz, and L. Guarente, Mol. Cell. Biol. 6:1936-1942, 1986). We show here that CIT2 encodes a nonmitochondrial form of citrate synthase. The DNA sequence of CIT2 presented provides a possible explanation for why the CIT2 product, unlike the CIT1 product, fails to be imported into mitochondria. While the products of these two genes are highly homologous, they diverge strikingly at their amino termini. The amino terminus of the CIT1 primary translation product extends 39 residues beyond the amino termini of Escherichia coli and porcine citrate synthases. This extension consists of a typical mitochondrial targeting motif. The amino terminus of the CIT2 primary translation product extends 20 residues beyond the amino termini of the E. coli and porcine enzymes. The CIT2-encoded extension is not homologous to that of CIT1, resulting in a nonmitochondrial localization of the product. The CIT2-encoded extension, however, does bear certain similarities to mitochondrial targeting sequences. The possible role of this sequence in targeting this CIT2 product to a nonmitochondrial organelle is discussed.
TL;DR: The membrane lipids of pea thylakoids were hydrogenated in situ using the homogeneous catalyst palladiumdi (sodium alizazine monosulphonate) as mentioned in this paper.
TL;DR: This work investigates the relationship of t(G) to other parameters associated with G : the number of vertices and edges, the radius, the independence number, maximum clique size and connectivity, and formulate bounds for a Ramsey-type function, N(k, t), the smallest integer.
TL;DR: Here it is shown that gk,n = k·n for k n 2 .
TL;DR: The monoclonal antibody COS-1 was found to bind to certain cone outer segments of many other vertebrate species as well and is assumed to represent an antibody against a common epitope of all visual pigments of the chicken.
TL;DR: In this article, the effect of metal dispersion on the competitive hydrogenation of a mixture containing 0.3% C/sub 2/H/sub 4/ over Pd/alumina as catalyst was investigated.
TL;DR: A Rhizobium meliloti DNA region (nodD1) involved in the regulation of other early nodulation genes has been delimited by directed Tn5 mutagenesis and its nucleotide sequence has been determined.
TL;DR: In this article, a detailed description of the environments near the nucleus of the comet P/Halley has been developed to support spacecraft and mission design for the flyby encounters in March 1986.
Abstract: Quantitative descriptions of environments near the nucleus of comet P/Halley have been developed to support spacecraft and mission design for the flyby encounters in March, 1986. To summarize these models as they exist just before the encounters, the relevant data from prior Halley apparitions and from recent cometary research are reviewed. Orbital elements, visual magnitudes, and parameter values and analysis for the nucleus, gas and dust are combined to predict Halley's position, production rates, gas and dust distributions, and electromagnetic radiation field for the current perihelion passage. The predicted numerical results have been useful for estimating likely spacecraft effects, such as impact damage and attitude perturbations. Sample applications are cited, including design of a dust shield for spacecraft structure, and threshold and dynamic range selection for flight experiments. It is expected that the comet's activity may be more irregular than these smoothly varying models predict, and that comparison with the flyby data will be instructive.
TL;DR: The hypothesis that multimodal sensory inputs are likely to be involved in the initiation or modulation of feeding in Lymnaea and act at several levels in the system is supported.
Abstract: Transfer of snails from distilled water to solutions of sucrose or maltose stimulated feeding behaviour. As the concentrations were increased from 10 −5 mol l −1 to 10 −1 mol l −1 the proportions of snails showing feeding movements and the median rate of feeding both increased until at 10 −3 mol 1 −1 they reached a plateau. At higher concentrations (10 −1 mol l −1 ), maltose, but not sucrose, reduced the proportion of feeding snails and median feeding rate to values occurring at 10 −5 mol 1 −1 . Increases in median feeding rate were due to an increase in the regularity of the feeding rhythm rather than increases in the maximum rates of feeding. Sugars and tactile stimuli were applied to putative sensory structures (interior of the buccal mass, lips and tentacles) in two types of semi-intact preparation whilst intracellular recordings were made from feeding motoneurones (1, 3, 4, 5 and 7 cells) and higher-order interneurones (Cerebral Giant Cells, CGCs, and the Slow Oscillator, SO). Both types of sensory stimuli applied to the lip-tentacle preparation produced strong activation of the CGCs but only long latency weak excitation of motoneurones with no clear initiation of synaptic inputs from central pattern generating (CPG) interneurones. In a more complex lip-tentacle-buccal mass preparation the evoked responses to sugars were comparable to those in the intact snail. Initiation of motoneuronal activity or increased frequency of activity was observed. This was due to increased CPG synaptic inputs as well as activation of a modulatory interneurone, the SO. Multiple sensory pathways from the periphery, present only in the lip-tentacle-buccal mass preparation, were necessary for sensory initiation of the feeding rhythm. The results support the hypothesis that multimodal sensory inputs are likely to be involved in the initiation or modulation of feeding in Lymnaea and act at several levels in the system. Note:
Journal Article•
TL;DR: CH-38083 failed to show any affinity for histamine and muscarinic receptors and it even potentiated the effect of serotonin on atropinized longitudinal muscle strip of guinea pig ileum and it enhanced the release of [3H]norepinephrine from electrically stimulated mouse vas deferens loaded previously with labeled [3 H]nOREpinephrine.
Abstract: The selectivity and specificity of CH-38083 [7,8-(methylenedioxi)-14-alpha-hydroxyalloberbane HCl], a berbane derivative for alpha adrenoceptors has been studied and compared with yohimbine and idazoxan in peripheral tissues and in the central nervous system. In isolated tissue experiments CH-38083 was a competitive antagonist at presynaptic alpha-2 adrenoceptors on the axon terminals of the rat vas deferens (pA2 against xylazine = 8.17 +/- 0.06) and of the longitudinal muscle strip of guinea pig ileum (pA2 against xylazine = 8.07 +/- 0.20). As far as its postsynaptic alpha-2 adrenoceptor antagonistic activity is concerned its affinity in rat vas deferens (pA2 = 4.95 +/- 0.11) against l-phenylephrine and in rabbit pulmonary artery (pA2 = 5.38 +/- 0.33 against l-norepinephrine) was markedly less than that displayed for presynaptic sites. From pA2 values obtained in rat vas deferens the calculated alpha-1/alpha-2 adrenoceptor selectivity ratios for yohimbine, idazoxan and CH-38083 were 4.7, 117.5 and 1659, respectively. CH-38083 failed to show any affinity for histamine and muscarinic receptors and it even potentiated the effect of serotonin on atropinized longitudinal muscle strip of guinea pig ileum. It enhanced the release of [3H]norepinephrine from electrically stimulated mouse vas deferens loaded previously with labeled [3H]norepinephrine. In binding studies carried out in rat brain membrane preparations using [3H]prazosin and [3H]idazoxan, the selectivity ratios (Ki alpha-1/Ki alpha-2) proved to be 32.5, 289.5 and 1368 for yohimbine, idazoxan and CH-38083, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)