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1.
Ivor P. B. Tittawella 《Molecular & general genetics : MGG》1985,200(1):114-117
Summary A mutation located near rpoB (89) in E. coli is responsible for unusual patterns of and (but not L7/L12) synthesis in response to the drugs rifampicin and acridine orange. 相似文献
2.
J. Visscher R. van der Woerd C. G. Bakker Alan W. Schwartz 《Origins of life and evolution of the biosphere》1989,19(1):3-6
Evidence is presented that a poly(U) template selectively favors the oligomerization of the activated, 3–5 pyrophosphate-linked dimer pdAppdAp, in comparison with the 3–3 and 5–5 linked dimers. In the absence of poly(U), the 5–5linked dimer is the most reactive, and chains are formed which are more than 60 monomer units in length.Nucleic Acid-Like Structures V. For the previous paper in this series see Visscher and Schwartz (1988). 相似文献
3.
John L. Trotter Cindy L. Wegescheide William F. Garvey Wallace W. Tourtellotte 《Neurochemical research》1984,9(1):147-152
Using radioimmunoassays (RIA) for the myelin specific proteins, myelin proteolipid protein (PLP) and myelin basic protein (MBP) and an enzyme assay for the activity of the myelin marker enzyme 23 cyclic-3 phosphohydrolase (CNPase), we have studied plaque, periplaque and normal appearing white matter (NAWM) regions of multiple sclerosis (MS) brain tissue, as well as normal control brain tissue. We found that all three myelin proteins are decreased in all regions, including NAWM, of MS brain, with a decreasing gradient from NAWM to periplaque to plaque. The NAWM was not significantly different from the periplaque region. Surprisingly, when the ratios of the proteins were calculated, MBP activity, although decreased was found to be relatively preserved. 相似文献
4.
Anna-Maria de Nysschen B -E. van Wyk Fanie R. van Heerden 《Plant Systematics and Evolution》1998,212(1-2):1-11
A study of the phenolic compounds of the closely related papilionoid tribes,Podalyrieae andLiparieae, proved that the flavonoid patterns of hydrolysed seed extracts are remarkably conservative. Butin (7, 3, 4-trihydroxyflavanone), 3-hydroxydaidzein (7, 3, 4-trihydroxyisoflavone), vicenin-2 (6, 8-di--D-glucopyranosyl-5, 7, 4-trihydroxyflavone) and orobol (5, 7, 3, 4-tetrahydroxyisoflavone) were isolated and identified as the major flavonoids. The seeds ofAmphithalea, Coelidium, Liparia, Xiphotheca, Calpurnia, Stirtonanthus andPodalyria accumulated three isoflavone O-glycosides that yielded 3-hydroxydaidzein on hydrolysis. In contrast,Virgilia contained a unique combination of vicenin-2 and orobol. Vicenin-2 was also present inCalpurnia as a major compound, butStirtonanthus insignis was the only other species studied that contained orobol (in trace amounts only). Butein, a chalcone, was reported byHarborne from the seed ofCyclopia subternata. This compound's flavanone analog, butin, was the principal component inCyclopia. A cladistic analysis, using flavonoid, alkaloid and morphological data, showed that the seed flavonoids of thePodalyrieae andLiparieae behave rather poorly as cladistic characters. They are, however, of considerable taxonomic value at the tribal level favouring the opinion that the two tribes should be combined. The apparent absence of flavonoids in the seed ofHypocalyptus supports the suggestion that it should be excluded from theLiparieae. Flavonoids also show that theArgyrolobium-group is very different from the tribeCrotalarieae and support the recent transfer of this group to the tribeGenisteae. 相似文献
5.
Summary Unlike cyclophosphamide (Endoxan®, Cytoxan®) N, N, N-tris-(2-chloroethyl)-N,O-propylene phosphoric acid ester diamide and N-(2-chloroethyl)-N-(2-chloroethyl)-N,-O-propylene phosphoric acid ester diamide induced chromosomal aberrations in human leukocytes in vitro. The majority of these lesions consisted of chromatid breaks, acentric fragments, and isochromatid breaks. Infrequently interchanges and ring chromosomes were observed. The percentage of metaphases with chromosomal damage increased exponentially, the mean breakage frequency per metaphase, however, rose approximately linearly with the applied concentration. A possible cleavage of the nitrogen-phosphorus bond and the breakdown of the inactive cyclic forms of the two investigated compounds in vitro is discussed.
(Direktor: Klinik der Freien Universität Berlin)
Herrn Professor Dr. Hans Frhr. von Kress zum 65. Geburtstag gewidmet. 相似文献
(Direktor: Klinik der Freien Universität Berlin)
Herrn Professor Dr. Hans Frhr. von Kress zum 65. Geburtstag gewidmet. 相似文献
6.
Gerhard Melcher 《Radiation and environmental biophysics》1970,7(1):29-32
Summary The difference in stabilisation between DNA and RNA is explained by assuming that the 2 hydrogen of the ribose penetrates into the-electron cloud of the base of the 5 linked nucleotide. 相似文献
7.
Thomas V. Waehneldt Joachim Malotka Gunnar Jeserich Jean-Marie Matthieu 《Environmental Biology of Fishes》1991,32(1-4):131-143
Synopsis Myelin was isolated from the brain of a coelacanth. Its protein components were separated by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate (SDS-PAGE). A protein component of 25000 Dalton was predominant; it was not glycosylated but reacted moderately with anti-mammalian CNS myelin proteolipid protein (PLP) antibodies and weakly with anti-lungfish CNS myelin glycosylated proteolipid protein (gPLP) antibodies. A component equivalent to mammalian DM-20 was not detectable. Presumably due to autolysis myelin basic protein (MBP) was not discernible by protein staining but showed up as a single band of 17000 Dalton with anti-mammalian MBP antibodies. Wolfgram protein (WP) was not present upon immunoblotting and the values for the myelin-specific 2, 3-cyclic nucleotide 3-phosphodiesterase (CNPase) were extremely low. These results question a chondrichthyan association of the coelacanth but are strongly in favor of an Actinistia-Tetrapoda sister group relationship, with Dipnoi being most closely related to that combined group. 相似文献
8.
Teruo Yoshino Minobu Sadamitsu Megumi Minagawa Gerd Reuter Roland Schauer 《Glycoconjugate journal》1988,5(4):377-384
The preparation of benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside, which is a key intermediate for chemical synthesis of oligosaccharide components of glycosphingolipids, was achieved by an improved method. The 3-O-p-methoxybenzyl and 3-O-methyl derivatives were prepared from benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside through stannylation. By using benzyl -d-lactoside as starting material, benzyl 3-O-methyl-, 3-O-benzyl- and 3-O-p-methoxybenzyl--d-lactoside were regioselectively synthesized using the same procedure. 相似文献
9.
Brigitta Bienz-Tadmor Peter Tolias Barbara Stebbins-Boaz Brian D. Mariani Susan A. Gerbi Fotis C. Kafatos 《Chromosoma》1992,101(9):538-548
P element mediated germ-line transformation was used to study the developmental specificity ofDrosophila chorion gene regulatory sequences directing expression of the bacterial reporter genes for chloramphenicol acetyltransferase (CAT) and -galactosidase (lacZ). DNA fragments containing 5 flanking plus the entire 5 untranslated and the beginning of the coding region of either thes36 or thes15 chorion gene are able to confer on the reporter genes normal tissue as well as temporal specificity of expression, exclusively in the ovary of transformed female flies. However, if 5 untranslated and coding regions are omitted, normal ovarian expression is maintained but tissue specificity is relaxed: expression of the reporter gene is detected both in the ovary and in specific non-ovarian tissues of transformed females and males. The evidence suggests that the missing 5 untranslated and coding sequences may include negative elements that normally suppress expression in non-ovarian tissues, and that these putative elements are distinct from those that prevent premature expression in the ovarian follicles. The exact location of ectopiclacZ expression within the internal male genitalia depends on the constellation of 5 flanking chorion regulatory sequences included in theP element constructs. Ectopic expression of theCAT gene in the male genitalia unders15 promoter control can be abolished by mutating the hexamer TCACGT, a sequence previously shown to be essential for the normal expression of this chorion gene in the ovary.by A. Spradling 相似文献
10.
All stereoisomers of xanthoxin (XAN) and abscisic aldehyde (ABA-aldehyde) were prepared from (R) and (S)-4-hydroxy--cyclogeraniol via asymmetric epoxidation. Their stomatal closure activities were measured on epidermal strips of Commelina communis L. Natural (S)-ABA-aldehyde showed strong activity comparable to that of (S)-abscisic acid (ABA). Natural (1S, 2R, 4S)XAN and (1S, 2R, 4R)-epi-XAN also induced stomatal closure at high concentrations. On the other hand, unnatural (1R)-enantiomers of XAN, epi-XAN, and ABA-aldehyde were not effective. To further examine the Stereoselectivity on the biosynthetic pathway to ABA, deuterium-labeled substrates were prepared and fed to Lycopersicon esculentum Mill, under non-stressed or water-stressed conditions. Substantial incorporations into ABA were observed in the cases of natural (1S, 2R, 4S)-XAN, (1S, 2R, 4R)-epi-XAN and both enantiomers of ABA-aldehyde, leading to the following conclusions. The negligible effect of unnatural (1R)-enantiomers of XAN, epi-XAN and ABA-aldehyde can be explained by their own biological inactivity and/or their conversion to inactive (R)-ABA. Even in the isolated epidermal strips, putative aldehyde oxidase activity is apparently sufficient to convert ABA-aldehyde to ABA while the activity of XAN dehydrogenase seems very weak. The stereochemistry of the 1, 2-epoxide is very important for the XAN-dehydrogenase while this enzyme is less selective regarding the 4-hydrdxyl group of XAN and converts both (1S, 2R, 4S)-XAN and (1S, 2R, 4R)-epi-XAN to (S)-ABA-aldehyde. Abscisic aldehyde oxidase can nonstereoselectively convert both (S) and (R)-ABA-aldehyde to biologically active (S) and inactive (R)-ABA, respectively.Abbreviations ABA
abscisic acid
- ABA-aldehyde
abscisic aldehyde
- DET
diethyl tartrate
-
epi-XAN
xanthoxin epimer
- FCC
flash column chromatography
- GC-EI-MS
gas chromatography-electron impact-mass spectrometry
- MeABA
abscisic acid methyl ester
- IR
infrared
- NMR
nuclear magnetic resonance
- PCC
pyridinium chlorochromate
- THF
tetrahydrofuran
- XAN
xanthoxin
The authors are very grateful to Mr J.K. Heald (Department of Biological Sciences, University of Wales, Aberystwyth, UK) and Dr. R. Horgan for carrying out GC-EI-MS analyses and advice, respectively.This work was supported by the Japan Society for the Promotion of Science (Fellowship for Young Japanese Researcher No. 0040672). 相似文献
11.
Richard Kuhn Mortimer P. Starr Daisy A. Kuhn Helmut Bauer Hans-Joachim Knackmuss 《Archives of microbiology》1965,51(1):71-84
Zusammenfassung Die extracelluläre Abscheidung eines unlöslichen blauen Pigments (Indigoidin) wurde zuerst bei Pseudomonas indigofera beobachtet. Historisch wird auf die verschiedenen Benennungen dieses Bakteriums eingegangen. Beschrieben wird die Darstellung blauer Farbstoffe aus Kulturen verschiedener Bakterien. Die von Corynebacterium insidiosum, Arthrobacter atrocyaneus und Arthrobacter polychromogenes gebildeten Pigmente sind identisch mit Indigoidin von P. indigofera. Die Identität wird bewiesen durch physikalische und chemische Vergleiche der Pigmente und ihrer Derivate. Der Name Indigoidin, der früher nur für das Pigment von P. indigofera verwendet wurde, wird nun unabhängig von der Herkunft des Pigments benützt.Indigoidin (I), C10H8N4O4, ist 5,5-Diamino-4,4-dihydroxy-3,3-diazadiphenochinon-(2,2). Durch Erhitzen mit 6 n HCl entsteht daraus ein Hydrolyseprodukt (III), C10H6N2O6, das als 4,5,4,5-Tetrahydroxy-3,3-diazadiphenochinon-(2,2) erkannt wurde. Dieses Hydrolyseprodukt (III) bildet ein Monokaliumsalz (VII), das identisch ist mit dem grünen Pigment, das Arthrobacter crystallopoietes bei Zusatz von Pyridon-(2) bildet. Über Synthesen des Indigoidins (I) und seines Hydrolyseprodukts (III), die von 3,3-Bipyridyl, von Citrazinsäure oder 5-Amino-pyridon-(2) ausgehen, wird an anderer Stelle berichtet.Beschrieben wird die Darstellung folgender Indigoidin-Derivate: 5,5-Diacetamino-4,4-dihydroxy-3,3-diazadiphenochinon-(2,2) (II), C14H12N4O6; 4,4-Dihydroxy-5,5-diacetoxy-3,3-diazadiphenochinon-(2,2) (IV), C14H10N2O8; 2,5,6,2.5.6-Hexaacetoxy-3,3-bipyridyl (VI), C22H20N2O12 und 4,4-Dihydroxy-5,5-dimethoxy-3,3-diazadiphenochinon-(2,2) (V), C12H10N2O6. 相似文献
12.
Summary Four E. coli Hfr strains, representing stable (Hfr Cavalli), moderately stable (AB312) and unstable (Ra-1, Ra-2) Hfr states, were used in the isolation of a series of F plasmids. Type II Fs were found to be the most prevalent F plasmid formed from all of the Hfrs, while the percentages of tra Fs increased as the stability of the Hfr increased. Two observations suggested that F formation in unstable Hfrs like Ra-2 may proceed through a type II F precursor. First, the major F products of Ra-2 are tra
+ type II Fs and, second, other F types (I, II) and classes (tra
+, tra) from Ra-2 appeared to be deletion derivatives of a larger F progenitor. By monitoring the molecular changes that occur when the Ra-2 derived type II F pWS200 is transferred from one recA host to another, we have found that all F types and classes can be generated from pWS200 in a recA-independent manner. F sequences involved in the genetic conversions of pWS200 include the oriT locus and the directly repeated junctions of F and chromosomal DNA. A model for the formation of Fs in unstable Hfrs is postulated in which a tra
+ type II F primary excision product is seen to be modified, through recA-independent processes, to other F types and classes. This model differs from the current model of F formation in that independent excision events from the Hfr chromosome are not seen as the source of type I and type II Fs.These studies have also shown that the formation of tra Fs is a recA-independent process that can occur from the F and Hfr states, that -mediated deletions in pWS200 often demonstrate regional specificity in having endpoints near the ilv operon and that genetic alterations in either replication origin of pWS200 (F oriV, chromosomal oriC) stabilize the replication of this mini-Hfr cointegrate. 相似文献
13.
Wayne Paul Maddison 《Chromosoma》1982,85(1):23-37
Observations of male meiosis and female chromosome number indicate that eight species of Pellenes have the X1X2O male, X1X1X2X2 female sex chromosome system typical of salticids, four species have an X1X2X3Y male, X1X1X2X3X3X3 female system, and one species has both X1X2O and X1X2X3Y males. This is the first report of a Y chromosome in spiders. It is hypothesized that the X1X2X2Y system was derived from an X1X2O system by a tandem X-autosome fusion which yielded the X2 and a centric autosome-autosome fusion which yielded the Y. Data on heteropycnosis, chiasmata, segregation, chromosome number and arm length support this hypothesis. The distribution of the X1X2X3Y system within the genus is phylogenetically confusing and suggests that the two sex chromosome systems have been maintained together as a polymorphism in some lineages for long periods of time or that there have been repeated derivations of the X1X2X3Y or X1X2O systems. 相似文献
14.
Summary In this first article on the carotenoids of Myxobacterales we report on the minor carotenoids of Stigmatella aurantiaca: phytoene, phytofluene, lycopene, -carotene, 4-keto--carotene, 1,2-dihydro-1-hydroxy--carotene, 4-keto-1,2-dihydro-1-hydroxy--carotene, 4-keto-1,2-dihydro-1-hydroxy-torulene, and 1,2,1,2-tetrahydro-1,1-dihydroxy-lycopene. These pigments account for about 10% of total carotenoids. 相似文献
15.
B. P. Gottikh A. A. Krayevsky M. K. Kukhanova A. A. Jatsyna A. M. Kritzyn C. L. Florentiev 《Molecular biology reports》1973,1(3):173-178
Peptide acceptor properties of phenylalanine and glycine esters of 9-(2,3-dihydroxypropyl-1)-adenine and 1-(2,3-dihydroxypropyl-1)-4-thiouracyl were investigated. All these esters appeared to be powerful inhibitors of polyphenylalanine synthesis in E. coli MRE-600 ribosomes charged with poly U. Like puromycin, esters of adenine derivatives accepted the AcPhe residue from Ac-[14C] Phe-tRNA in a ribosomal system charged with poly U. However, peptidyl esters of 9-(2,3-dihydroxypropyl-1)-adenine remained bound with ribosomes. The structure of the peptide esters synthesized was ascertained after dissociation of ribosomes into subparticles by direct comparison with the synthetic specimens.Abbreviations AcPhe
acetyl-l-phenylalanine
- HP-Ade
9-(2,3-dihydroxypropyl-1)-adenine
- Phe-HP-Ade and Gly-HP-Ade
l-phenylalanine and glycine esters of HP-Ade
- Phe-HP-TUra
l-phenylalanine ester 1-(2,3-dihydroxypropyl-1)-4-thiouracyl
- AcPhePhe-HP-Ade and AcPheGly-HP-Ade
acetyl-l-diphenylalanine and acetyl-l-phenylalanylglycine esters of HP-Ade respectively
- AcPhe-puromycin
acetyl-l-phenylalanyl-puromycin 相似文献
16.
Summary The absence of the methyl substituent at the 2position of the cyclohexene ring of TCHP enhances the conversion rate as well as the yields of the 3-hydroxy product obtained byStreptomyces natalensis and the 3-keto product obtained byMycobacterium smegmatis.Abbreviations TCHP
1-(2-thienyl)-3-(1-cyclohexen-1-yl)-1-propanone
- TCHP-OH
1-(2-thienyl)-3-(3-hydroxyl-1-cyclohexen-1-yl)-1-propanone
- TCHP-ketone
1-(2-thienyl)-3-(1-cyclohexen-1-yl-3-one)-1-propane
- TMCHP
1-(2-thienyl)-3-(2-methyl-1-cyclohexen-1-yl)-propanone 相似文献
17.
DNA polymerases II () and III() are the only nuclear DNA polymerases known to possess an intrinsic 3 5 exonuclease in Saccharomyces cerevisiae. We have investigated the spontaneous mutator phenotypes of DNA polymerase and 3 5 exonuclease-deficient mutants, pol3-01 and pol2-4, respectively. pol3-01 and pol2-4 increased spontaneous mutation rates by factors of the order of 102 and 101, respectively, measured as URA3 forward mutation and his7-2 reversion. Surprisingly, a double mutant pol2-4 pol3-01 haploid was inviable. This was probably due to accumulation of unedited errors, since a pol2-4/pol2-4 pol3-01/pol3-01 diploid was viable, with the spontaneous his7-2 reversion rate increased by about 2 × 103-fold. Analysis of mutation rates of double mutants indicated that the 3 5 exonucleases of DNA polymerases and can act competitively and that, like the 3 5 exonuclease of DNA polymerase the 3 5 exonuclease of DNA polymerase acts in series with the PMS1 mismatch correction system. Mutational spectra at a URA3 gene placed in both orientations near to a defined replication origin provided evidence that the 3 5 exonucleases of DNA polymerases and act on opposite DNA strands, but were in sufficient to distinguish conclusively between different models of DNA replication. 相似文献
18.
In the course of characterization of glycolipid sulfotransferase from human renal cancer cells, the manner of inhibition of sulfotransferase activity with pyridoxal 5-phosphate was investigated. Incubation of a partially purified sulfotransferase preparation with pyridoxal 5-phosphate followed by reduction with NaBH4 resulted in an irreversible inactivation of the enzyme. When adenosine 3-phosphate 5-phosphosulfate was co-incubated with pyridoxal 5-phosphate, the enzyme was protected against this inactivation. Furthermore, pyridoxal 5-phosphate was found to behave as a competitive inhibitor with respect to adenosine 3-phosphate 5-phosphosulfate with aK
i value of 287 µm. These results suggest that pyridoxal 5-phosphate modified a lysine residue in the adenosine 3-phosphate 5-phosphosulfate-recognizing site of the sulfotransferase. 相似文献
19.
Wei Tong Wang Fumito Matsuura Hernan Nunez Norman Ledonne Jr. Betty Baltzer Charles C Sweeley 《Glycoconjugate journal》1984,1(1):17-35
Ten previously unreported oligosaccharides have been purified from the urines of human subjects using a combination of gel filtration, ion exchange, and thin-layer chromatographies. Their structures were determined by direct probe mass spectrometry, methylation analysis, and proton NMR spectroscopy of the permethylated oligosaccharide alditols.On the basis of composition, the oligosaccharides could be divided into three groups. Five oligosaccharides containing glycerol were characterized as glucosyl1-1glycerol; glucosyl1-1glycerol; galactosyl1-1glycerol; glucosyl-1-1(fucosyl-1-2)glycerol and/or fucosyl-1-1(glucosyl-1-2)glycerol; and glucosyl-1-1(galactosyl-1-2)glycerol or galactosyl-1-1(glucosyl-1-2)glycerol. Four inositol-containing oligosaccharides were characterized as galactosyl1 (fucosyl1)inositol,N-acetylgalactosaminyl1 (fucosyl1)inositol, fucosyl1-2galactosyl1 (N-acetylgalactosaminyl1)inositol and fucosyl1-2galactosyl1-4-N-acetylglucosaminyl1(N-acetylgalactosaminyl1)inositol. Finally, galactosyl1-3(fucosyl1-2)galactosyl1-6galactosyl1-4(fucosyl1-3)glucose, an oligosaccharide with glucose at its reducing end, was tentatively identified. The significance and possible origins of the carbohydrate structures are discussed. 相似文献
20.
Summary The aminoacylation of diinosine monophosphate (IpI) was studied. When the acylating agent was the imidazolide of N-(tert-butoxycarbonyl)-Dl-alanine, a 40% enantiomeric excess of thel isomer was incorporated at the internal 2 site and the positions of equilibrium for the 23 migration reaction differed for theD andl enantiomers. The reactivity of the nucleoside hydroxyl groups decreased in the order 2(3)>internal 2>5, and the extent of reaction was affected by the concentration of the imidazole buffer (pH 7.1). In contrast, reaction of IpI with the imidazolide of unprotectedDl-alanine led to an excess of theD isomer at the internal 2 site, while reaction with the N-carboxy anhydride ofDl-alanine proceeded without detectable stereoselection. The relevance of these results to the evolution of optical activity and the origin of genetically directed protein synthesis is discussed. 相似文献