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1.
From heptose transferase-less Re mutants of Salmonella minnesota and Shigella sonnei, a mixture of nucleotide-linked heptoses was isolated. After paper chromatography in different solvent systems, ADP derivatives of D-glycero-D-mannoheptose and L-glycero-D-mannoheptose could be isolated in pure form. The structure of ADP-L-glycero-D-mannoheptose was verified by analytical methods and by transformation of ADP-D-glycero-D-mannoheptose with ADP-D-glycero-D-mannoheptose-6-epimerase. 相似文献
2.
D. Egg H. Altman R. Günther W. Klein F. Kocsis 《Prostaglandins & other lipid mediators》1978,15(3):437-446
experiments were performed on mouse spleen cells to establish possible influences of some naturally occurring prostaglandins on DNA synthesis and DNA excision repair. The prostaglandins A1, B1, E1, E2 and F2 were tested in concentrations of lopg, 5ng and 2.5μg per ml cell suspension. DNA synthesis was significantly increased by pgF2α in all the three concentrations tested, while the other tested prostaglandins were essentially ineffective. DNA excision repair was significantly inhibited by PgF1 and PgF2 at 5ng/'ml and at 2.5μg/ml but increased by PgF2α in the two lower concentrations. The rejoining of DNA-strand breaks after γ-irradiation was slightly reduced by PgF1, PgE2 and PgF2α at 2.5μg/ml. 相似文献
3.
Image averaging of flexible fibrous macromolecules: the clathrin triskelion has an elastic proximal segment. 总被引:5,自引:0,他引:5
We have developed computational techniques that allow image averaging to be applied to electron micrographs of filamentous molecules that exhibit tight and variable curvature. These techniques, which involve straightening by cubic-spline interpolation, image classification, and statistical analysis of the molecules' curvature properties, have been applied to purified brain clathrin. This trimeric filamentous protein polymerizes, both in vivo and in vitro, into a wide range of polyhedral structures. Contrasted by low-angle rotary shadowing, dissociated clathrin molecules appear as distinctive three-legged structures, called "triskelions" (E. Ungewickell and D. Branton (1981) Nature 289, 420). We find triskelion legs to vary from 35 to 62 nm in total length, according to an approximately bell-shaped distribution (mu = 51.6 nm). Peaks in averaged curvature profiles mark hinges or sites of enhanced flexibility. Such profiles, calculated for each length class, show that triskelion legs are flexible over their entire lengths. However, three curvature peaks are observed in every case: their locations define a proximal segment of systematically increasing length (14.0-19.0 nm), a mid-segment of fixed length (approximately 12 nm), and a rather variable end-segment (11.6-19.5 nm), terminating in a hinge just before the globular terminal domain (approximately 7.3 nm diameter). Thus, two major factors contribute to the overall variability in leg length: (1) stretching of the proximal segment and (2) stretching of the end-segment and/or scrolling of the terminal domain. The observed elasticity of the proximal segment may reflect phosphorylation of the clathrin light chains. 相似文献
4.
The dissociation of cardiovascular (arterial hypertension) and respiratory (depression) reactions to severe cerebral ischemia seems to be inconsistent with the usual cooperative behavior of the two systems and their role in managing disturbances in the central chemical environment. In the present study the Cushing reaction was elicited by transient increase of the intracranial pressure 4-11 times in each experiment. The pressor response and changes in the vertebral sympathetic nerve discharge (SND) were compared with the respiratory reaction and with changes in the phrenic nerve activity. The reaction in both nerves developed in two phases. In the phrenic nerve, an initial hyperactivity (increased discharge amplitude and frequency) coincided with augmentation of the rhythmic SND (phase 1) and complete nerve depression developed when the SND was desynchronized (phase 2). The transition in both systems correlated in their latencies and the severity of the ischemia needed for their stimulation. Repetition of the ischemic stimuli increased the occurrence of the respiratory-related rhythmicity in the SND and later changed its character from rhythmic amplitude modulation to respiratory-related high-frequency bursting SND coinciding with the inspiration. It is concluded that, despite the apparent dissociation between the cardiovascular and respiratory reactions, there is a parallel response between the neurophysiological correlates of the two systems to increasing severity of cerebral ischemia. 相似文献
5.
K. Böjthe-Horváth F. Hetényi Á. Kocsis L. Szabó M. Varga-Balázs I. Máthé P. Tétényi 《Phytochemistry》1980,21(12):2917-2919
From the aerial parts of Galium verum in flower, asperuloside and V1 iridoid were isolated. From the mother liquor obtained on recrystallizatio 相似文献
6.
Péter Poczai Jaakko Hyvönen János Taller Gizella Jahnke László Kocsis 《Plant Molecular Biology Reporter》2013,31(2):371-386
Teleki rootstocks are used in grapevine-producing countries all over the world. They represent one of the largest groups of available rootstocks but their origin is still in dispute although they have been regarded as Vitis berlandieri × V. riparia hybrids. To investigate their possible origin, we amplified and sequenced three chloroplast regions, two non-coding spacers (trnL-F, trnS-G) and the trnL group I intron in a core collection of Teleki rootstocks representing widespread accessions and related wild North American grape species (V. berlandieri, V. riparia and V. rupestris). Concatenated sequence data coupled with microstructural changes discovered in the chloroplast regions provided data to trace the maternal ancestry of the Teleki lines. All chloroplast regions showed both nucleotide and length variation. Length mutations in the non-coding regions represented mostly simple sequence repeats of poly-A and -T stretches. These indel characters exhibited additional diversity comparable with the nucleotide diversity and increased resolution of the phylogenetic trees. We found that a group of Teleki accessions position together with the wild grape species V. riparia. Another group of Teleki rootstocks formed a sister group to the other North American species V. berlandieri. These clades had moderate support values, and they do not share ancestry with other accessions of Teleki rootstocks resolved with high support value in the V. riparia clade. It seems that Teleki-Kober 5BB and 125 AA accessions might have a V. berlandieri maternal background. We also found great differences within putative clones of Teleki 5C and Teleki-Kober 5BB suggesting that the selection of these accessions was performed on heterogenous or mislabeled plant material collectively maintained under these names. 相似文献
7.
Phylogenetic relationships were determined for 76 partial P-element
sequences from 14 species of the melanogaster species group within the
Drosophila subgenus Sophophora. These results are examined in the context
of the phylogeny of the species from which the sequences were isolated.
Sequences from the P-element family fall into distinct subfamilies, or
clades, which are often characteristic for particular species subgroups.
When examined locally among closely related species, the evolution of P
elements is characterized by vertical transmission, whereby the P-element
phylogeny traces the species phylogeny. On a broader scale, however, the
P-element phylogeny is not congruent with the species phylogeny. One
feature of P-element evolution in the melanogaster group is the presence of
more than one P-element subfamily, differing by as much as 36%, in the
genomes of some species. Thus, P elements from several individual species
are not monophyletic, and a likely explanation for the incongruence between
P-element and species phylogenies is provided by the comparison of
paralogous sequences. In certain instances, horizontal transfer seems to be
a valid alternative explanation for lack of congruence between species and
P-element phylogenies. The canonical P-element subfamily, which represents
the active, autonomous transposable element, is restricted to D.
melanogaster. Thus, its origin clearly lies outside of the melanogaster
species group, consistent with the earlier conclusion of recent horizontal
transfer.
相似文献
8.
A. H. Nagy Dr. M. O. Siddiqui Z. G. Kocsis G. Vida 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1980,57(4):75-78
Summary Two allelic forms of NAD specific malate dehydrogenase were found in samples of a wild population of Corydalis solida. The dimeric nature and the origin of the heterodimeric form has been demonstrated by in vitro dissociation and recombination of the subunits detected by subsequent electrophoresis. The method is applicable for polyacrylamide gel electrophoresis of crude leaf extracts of individual MDH isozyme forms. 相似文献
9.
Görbe A Varga ZV Kupai K Bencsik P Kocsis GF Csont T Boengler K Schulz R Ferdinandy P 《American journal of physiology. Heart and circulatory physiology》2011,300(5):H1907-H1913
Cardioprotection by ischemic preconditioning (IP) was abolished in connexin 43 (Cx43)-deficient mice due to loss of Cx43 located in mitochondria rather than at the sarcolemma. IP is lost in hyperlipidemic rat hearts as well. Since changes in mitochondrial Cx43 in hyperlipidemia have not yet been analyzed, we determined total and mitochondrial Cx43 levels in male Wistar rats fed a laboratory chow enriched with 2% cholesterol or normal chow for 12 wk. Hearts were isolated and perfused according to Langendorff. After a 10-min perfusion, myocardial tissue cholesterol, superoxide, and nitrotyrosine contents were measured and Cx43 content in whole heart homogenate and a mitochondrial fraction determined. In the cholesterol-fed group, tissue cholesterol and superoxide formation was increased (P < 0.05), while total Cx43 content remained unchanged. Mitochondrial total and dephosphorylated Cx43 content decreased. Hearts were subjected to an IP protocol (3 × 5 min ischemia-reperfusion) or time-matched aerobic perfusion followed by 30-min global ischemia and 5-min reperfusion. IP reduced infarct size in normal but not in cholesterol-fed rats. At 5-min reperfusion following 30-min global ischemia, the total and dephosphorylated mitochondrial Cx43 content was increased, which was abolished by IP in both normal and high-cholesterol diet. In conclusion, loss of cardioprotection by IP in hyperlipidemia is associated with a redistribution of both sarcolemmal and mitochondrial Cx43. 相似文献
10.
K Sakatani J A Black J D Kocsis 《Proceedings. Biological sciences / The Royal Society》1992,247(1319):155-161
GABA (gamma-aminobutyric acid) is a major inhibitory synaptic neurotransmitter with widespread distribution in the central nervous system (CNS). GABA can also modulate axonal excitability by activation of GABAA receptors in CNS white matter regions where synapses and neuronal cell bodies are not present. Studies on cultured glia cells have revealed the synthesis of GABA in rat optic nerve O-2A progenitor cells that give rise to oligodendrocytes and type 2 astrocytes in vitro. We report here that: (i) GABA is detected by immuno-electron microscopy in intact rat optic nerve and is localized to glia and pre-myelinated axons during the first few weeks of postnatal development, but is markedly reduced or absent in the adult; and (ii) neonatal optic nerve is depolarized by GABAA receptor agonists or by the inhibition of GABA uptake. These results demonstrate the presence of functional GABAA receptors, and GABA uptake and release mechanisms in developing rat optic nerve, and suggest that excitability of developing axons can be modulated by endogenous neurotransmitter at non-synaptic sites. 相似文献