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  • Inorganic Chemistry  (5,240)
  • Industrial Chemistry  (1,362)
  • gene expression
  • Seismology
  • Wiley-Blackwell  (6,660)
  • Springer  (202)
  • 1990-1994  (3,929)
  • 1950-1954  (2,933)
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  • 1
    Electronic Resource
    Electronic Resource
    Changes in polypeptide patterns in tobacco roots colonized by two Glomus species (1994)
    Springer
    Mycorrhiza 4 (1994), S. 215-221 
    Details
    ISSN: 1432-1890
    Keywords: Nicotiana ; Glomus species ; arbuscular mycorrhiza ; gene expression ; specific polypeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in gene expression were studied during the establishment of arbuscular mycorrhizal symbiosis in tobacco roots from an amphidiploid hybrid Nicotiana glutinosa x N. debneyi. Polypeptide patterns from control roots and from roots infected by Glomus mosseae or G. intraradices were resolved by two-dimensional polyacrylamide gel electrophoresis and followed in a time-course analysis. Arbuscular mycorrhizal infection led to significant modifications in polypeptide patterns with: (a) decreased amounts of some polypeptides, (b) increased accumulation of others, and (c) appearance of newly-induced polypeptides. Comparisons made during infection development by the two Glomus species demonstrated that protein modifications changed in relation to the mycorrhizal state of the tobacco roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206783
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of radical scavengers on TNFα-mediated activation of the uPA in cultured cells (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 958-962 
    Details
    ISSN: 1420-9071
    Keywords: Plasminogen activator ; active oxygen ; gene expression ; radical scavengers ; endothelial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Active oxygen, produced by cultured cells following stimulation with various growth factors, seems to be involved in signal transduction leading to cellular responses such as gene expression and growth modulation. In the present study, the intracellular oxidation state was measured in immortalized human endothelial cells (ECV304) after treatment with tumor necrosis factor (TNF)α, using a fluorescent dye and a laser-scanning confocal microscope. The intracellular oxidation state was increased 60 min after the addition of TNFα, and this increase was abolished by a radical scavenger, N-acetylcysteine (NAC), which is also a precursor of glutathione, and by pyrrolidine dithiocarbamate (PDTC). TNFα increased the steady state level of urokinase-type plasminogen activator (uPA), and NAC inhibited this increase at a dose that also inhibited the increase in the intracellular oxidation state. PDTC, on the other hand, did not affect the induction of the uPA gene by TNFα. These results suggest that intracellular glutathione level rather than the oxidation state is necessary for the induction of the uPA gene by TNFα.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01923487
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  • 3
    Electronic Resource
    Electronic Resource
    Migration of seismic data (1994)
    Springer
    Journal of statistical physics 76 (1994), S. 703-723 
    Details
    ISSN: 1572-9613
    Keywords: Seismology ; migration ; scalar wave equation ; parallel computing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Prospecting for oil and gas resources poses the problem of determining the geological structure of the earth's crust from indirect measurements. Seismic migration is an acoustic image reconstruction technique based on the inversion of the scalar wave equation. Extensive computation is necessary before reliable information can be extracted from large sets of recorded data. In this paper a collection of “industrial” migration techniques, each giving rise to a data parallel algorithm, is outlined. Computer simulations on synthetic seismic data illustrate the problem and the approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02188682
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  • 4
    Electronic Resource
    Electronic Resource
    Expression of the c-myc and Ca-ATPase genes in cardiac muscle during adaptation to repeated stress (1994)
    Springer
    Bulletin of experimental biology and medicine 117 (1994), S. 122-124 
    Details
    ISSN: 1573-8221
    Keywords: gene expression ; c-myc ; Ca-ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the course of adaptation to repeated stress, the expression of the proto-oncogene c-myc found to increase much more rapidly than that of the Ca-ATPase gene. It is suggested that an increase in the level of c-myc expression may activate the structural Ca-ATPase gene and possibly also the heat-shock proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02444120
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of the mitochondrial creatine kinase genes (1994)
    Springer
    Molecular and cellular biochemistry 133-134 (1994), S. 235-243 
    Details
    ISSN: 1573-4919
    Keywords: creatine kinase ; mitochondria ; metabolism ; creatine phosphate shuttle ; gene expression ; muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Mitochondrial Creatine Kinase (MtCK) is responsible for the transfer of high energy phosphate from mitochondria to the cytosolic carrier, creatine, and exists in mammals as two isoenzymes encoded by separate genes. In rats and humans, sarcomere-specific MtCK (sMtCK) is expressed only in skeletal and heart muscle, and has 87% nucleotide identity across the 1257 bp coding region. The ubiquitous isoenzyme of MtCK (uMtCK) is expressed in many tissues with highest levels in brain, gut, and kidney, and has 92% nucleotide identity between the 1254 bp coding regions of rat and human. Both genes are highly regulated developmentally in a tissue-specific manner. There is virtually no expression of sMtCK mRNA prior to birth. Unlike cytosolic muscle CK (MCK) and brain CK (BCK), there is no developmental isoenzyme switch between the MtCKs. Cell culture models representing the tissue-specific expression of either sMtCK or uMtCK are available, but there are no adequate developmental models to examine their regulation. Several animal models are available to examine the coordinate regulation of the CK gene family and include 1) Cardiac Stress by coarctation (sMtCK, BCK, and MCK), 2) Uterus and placenta during pregnancy (uMtCK and BCK), and 3) Diabetes and mitochondrial myopathy (sMtCK, BCK, and MCK). We report the details of these findings, and discuss the coordinate regulation of the genes necessary for high-energy transduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01267957
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  • 6
    Electronic Resource
    Electronic Resource
    Transcriptional regulation and autoregulation of the human gene for ADP-ribosyltransferase (1994)
    Springer
    Molecular and cellular biochemistry 138 (1994), S. 99-104 
    Details
    ISSN: 1573-4919
    Keywords: poly(ADP-ribosyl) transferase (human) ; autoregulation ; gene expression ; promoter structure ; cruciform structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Human nuclear poly(ADP-ribosyl)transferase (ADPRT) modifies proteins with branched ADP-ribose-polymers. Various proteins, including ADPRT itself, serve as acceptors for polyADP-ribose. Target proteins include those controlling basic cellular processes such as DNA repair, differentiation and proliferation. Because of the outstanding features of this enzyme: automodification, several functional domains and central role in physiology of the cell, the molecular biology of ADPRT gained wide interest. The promoter structure contains several CCAAT/TATA boxes and SP1 sites. However, there is no CCAAT/TATA box in the neighbourhood of an SP1 site and, thus no obvious site for initiation of transcription. Within this region there are several noteworthy inverted repeats, which by internal basepairing could form two types of cruciform structures. Deletion analysis revealed that these cruciform structures have functional significance. Removal of one type increases the promoter activity, whereas removal of the other diminishes the promoter function. Overexpression of ADPRT from heterologous promoters (MMTV, SV40) leads to repression of the activity of the ADPRT promoter. Indeed, ADPRT was shown to bind specifically to one type of cruciform structure. This specific interaction indicates autorepression of the ADPRT gene: the enzyme ADPRT acts directly as a negative modulator of the activity of its own promoter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00928449
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  • 7
    Electronic Resource
    Electronic Resource
    Nuclear Ca2+: physiological regulation and role in apoptosis (1994)
    Springer
    Molecular and cellular biochemistry 135 (1994), S. 89-98 
    Details
    ISSN: 1573-4919
    Keywords: calcium ; cell death ; nuclei ; apoptosis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The last decade has seen the rapid development of research investigating the molecular mechanisms whereby hormones, peptide growth factors and cytokines regulate cell metabolism, differentiation and proliferation. One general signalling mechanism used to transfer the information delivered by agonists into appropriate intracellular compartments involves the rapid Ca2+ redistribution throughout the cell, which results in transient elevations of the cytosolic free Ca2+ concentration. Ca2+ signals are required for a number of cellular processes including the activation of nuclear processes such as gene transcription and cell cycle events. The latter require that appropriate Ca2+ signals elicited in response to agonists be transduced across the nuclear envelope. It has generally been assumed that small molecules, metabolites and ions could freely diffuse across the nuclear envelope. Nevertheless several findings during the past few years have suggested that nuclear pore permeability can be regulated and that ion transport systems and ion-selective channels may exist on the nuclear membranes and regulate intranuclear processes. Intranuclear Ca2+ fluctuations can affect chromatin organization, induce gene expression and also activate cleavage of nuclear DNA by nucleases during programmed cell death or apoptosis. The possible mechanisms involved in nuclear Ca2+ transport and the control of nuclear Ca2+-dependent enzymes in apoptosis is discussed below.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925964
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  • 8
    Electronic Resource
    Electronic Resource
    Expression of hepatic calcium-binding protein regucalcin mRNA is decreased by phenobarbital administration in rats (1994)
    Springer
    Molecular and cellular biochemistry 141 (1994), S. 15-19 
    Details
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; phenobarbital ; rat liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of phenobarbital on the expression of calcium-binding protein regucalcin mRNA in rat liver was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin cDNA (0.9 kb of open reading frame). Phenobarbital (4, 8 and 12 mg/ 100 g body weight) was intraperitoneally administered to rats 3 times with 24 h intervals, and the animals were sacrificed by bleeding at 24 h after the last administration. The hepatic regucalcin mRNA levels were markedly reduced by phenobarbital administration. This decrease was about 50% of control level with the 12 mg/100 g dose. Moreover, the hepatic regucalcin concentration was significantly decreased by the administration of phenobarbital (12 mg/100 g), although the serum regucalcin concentration was not altered appreciably. Meanwhile, serum transaminases (GOT and GPT) activities were not increased by the administration of phenobarbital (4 and 12 mg/100 g). The present study demonstrates that the expression of hepatic regucalcin mRNA is decreased by phenobarbital administration in rats, suggesting that regucalcin does not have a role in drug metabolism related to phenobarbital.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00935586
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  • 9
    Electronic Resource
    Electronic Resource
    Regulation of mRNA transcripts and DNA synthesis in the rat heart following intravenous injection of transforming growth factor beta1 (1994)
    Springer
    Molecular and cellular biochemistry 141 (1994), S. 145-151 
    Details
    ISSN: 1573-4919
    Keywords: pressure overload ; myocardium ; gene expression ; fibroblast ; extracellular matrix ; ventricular hypertrophy ; growth factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Transforming Growth Factor-beta1 (TGF-β1) is expressed in the heart by muscle and non-muscle cardiac cells.In vitro, cardiac myocytes and non-muscle cells including cardiac fibroblasts and endothelial cells respond to regulatory effects of TGF-β1. Expression of TGF-β1 in the heart is subject to regulation by hemodynamic stimuli. Increased expression of mRNA transcripts for TGF-β1 has been reported in several models of cardiac hypertrophy. The objective of this study was to determine the effect of TGF-β1 in the myocardium. TGF-β1 was injected intravenously. Expression of mRNA transcripts for functional and structural proteins was determined by Northern hybridization analysis. DNA synthesis was determined by measurement of3H-thymidine incorporation into ventricular DNA. The results showed differential regulation of mRNAs for myocyte- and non-myocyte-specific proteins in the heart of TGF-β1 treated rats. Moderate but statistically significant decrease in DNA synthesis was observed in the heart of TGF-β1 treated rats (37.5%, P〈0.025). Together, these data point to a physiological role for TGF-β1 in the heart. They further suggest that similar to its diversein vitro cell-specific regulatory effects, TGF-β1 may have multicellular targets in the heart. Effect of TGF-β1 alone or combined with those of other cytokines/hormones that come into play, as the result of its administration, may be responsible for altered gene expression and DNA synthesis in the myocardium. We propose that in experimental models of myocardial hypertrophy which are associated with increased expression of TGF-β1 in the heart, the contribution of regulatory effects of this growth factor to the manifestations of ventricular hypertrophy could be significant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00926178
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  • 10
    Electronic Resource
    Electronic Resource
    Mitochondrial DNA diseases: Histological and cellular studies (1994)
    Springer
    Journal of bioenergetics and biomembranes 26 (1994), S. 301-310 
    Details
    ISSN: 1573-6881
    Keywords: Mitochondrial encephalomyopathy ; mitochondrial DNA ; gene expression ; protein translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Large-scale deletions and tRNA point mutations in mitochondrial DNA (mtDNA) are associated with a variety of different mitochondrial encephalomyopathies. Skeletal muscle in these patients shows a typical pathology, characterized by the focal accumulation of large numbers of morphologically and biochemically abnormal mitochondria (ragged-red fibers). Both mtDNA deletions and tRNA point mutations impair mitochondrial translation and produce deficiencies in oxidative phosphorylation. However, mutant and wild-type mtDNAs co-exist (mtDNA heteroplasmy) and the translation defect is not expressed until the ratio of mutant: wild-type mtDNAs exceeds a specific threshold. Below the threshold the phenotype can be rescued by intramitochondrial genetic complementation. The mosaic expression of the skeletal muscle pathology is thus determined by both the cellular and organellar distribution of mtDNA mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00763101
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  • 11
    Electronic Resource
    Electronic Resource
    Photobiology of Bacteria (1994)
    Springer
    Antonie van Leeuwenhoek 65 (1994), S. 331-347 
    Details
    ISSN: 1572-9699
    Keywords: photoactive proteins ; photoreceptors ; chromophores ; energy transduction ; light signalling ; phototaxis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The field of photobiology is concerned with the interactions between light and living matter. For Bacteria this interaction serves three recognisable physiological functions: provision of energy, protection against excess radiation and signalling (for motility and gene expression). The chemical structure of the primary light-absorbing components in biology (the chromophores of photoactive proteins) is surprisingly simple: tetrapyrroles, polyenes and derivatised aromats are the most abundant ones. The same is true for the photochemistry that is catalysed by these chromophores: this is limited to light-induced exciton- or electron-transfer and photoisomerization. The apoproteins surrounding the chromophores provide them with the required specificity to function in various aspects of photosynthesis, photorepair, photoprotection and photosignalling. Particularly in photosynthesis several of these processes have been resolved in great detail, for others at best only a physiological description can be given. In this contribution we discuss selected examples from various parts of the field of photobiology of Bacteria. Most examples have been taken from the purple bacteria and the cyanobacteria, with special emphasis on recently characterised signalling photoreceptors inEctothiorhodospira halophila and inFremyella diplosiphon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00872217
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  • 12
    Electronic Resource
    Electronic Resource
    Strategies for improving heterologous protein production from filamentous fungi (1994)
    Springer
    Antonie van Leeuwenhoek 65 (1994), S. 245-250 
    Details
    ISSN: 1572-9699
    Keywords: Aspergillus ; gene expression ; heterologous protein ; protein secretion ; Trichoderma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Despite the naturally high capacity for protein secretion by many species of filamentous fungi, secteted yields of many heterologous proteins have been comparatively low. The strategies for yield improvement have included the use of strong homologous promoters, increased gene copy number, gene fusions with a gene encoding a naturally well-secreted protein, protease-deficient host strains and screening for high yields following random mutagenesis. Such approaches have been effective with some target heterologous proteins but not others. Approaches used in heterologous protein production from filamentous fungi are discussed and a perspective on emerging strategies is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00871952
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  • 13
    Electronic Resource
    Electronic Resource
    Photosynthetic electron transport and anaerobic metabolism in purple non-sulfur phototrophic bacteria (1994)
    Springer
    Antonie van Leeuwenhoek 66 (1994), S. 151-164 
    Details
    ISSN: 1572-9699
    Keywords: purple non-sulfur bacteria ; Rhodobacter ; photosynthesis ; CO2 fixation ; anaerobic respiration ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Purple non-sulfur phototrophic bacteria, exemplifed byRhodobacter capsulatus andRhodobacter sphaeroides, exhibit a remarkable versatility in their anaerobic metabolism. In these bacteria the photosynthetic apparatus, enzymes involved in CO2 fixation and pathways of anaerobic respiration are all induced upon a reduction in oxygen tension. Recently, there have been significant advances in the understanding of molecular properties of the photosynthetic apparatus and the control of the expression of genes involved in photosynthesis and CO2 fixation. In addition, anaerobic respiratory pathways have been characterised and their interaction with photosynthetic electron transport has been described. This review will survey these advances and will discuss the ways in which photosynthetic electron transport and oxidation-reduction processes are integrated during photoautotrophic and photoheterotrophic growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00871637
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  • 14
    Electronic Resource
    Electronic Resource
    Molecular biology of C4 phosphoenolpyruvate carboxylase: Structure, regulation and genetic engineering (1994)
    Springer
    Photosynthesis research 39 (1994), S. 115-135 
    Details
    ISSN: 1573-5079
    Keywords: C4 photosynthesis ; gene expression ; oligomerization ; phosphorylation-dephosphorylation cascade ; PEPC-protein kinase ; site-directed mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three to four families of nuclear genes encode different isoforms of phosphoenolpyruvate (PEP) carboxylase (PEPC): C4-specific, C3 or etiolated, CAM and root forms. C4 leaf PEPC is encoded by a single gene (ppc) in sorghum and maize, but multiple genes in the C4-dicot Flaveria trinervia. Selective expression of ppc in only C4-mesophyll cells is proposed to be due to nuclear factors, DNA methylation and a distinct gene promoter. Deduced amino acid sequences of C4-PEPC pinpoint the phosphorylatable serine near the N-terminus, C4-specific valine and serine residues near the C-terminus, conserved cysteine, lysine and histidine residues and PEP binding/catalytic sites. During the PEPC reaction, PEP and bicarbonate are first converted into carboxyphosphate and the enolate of pyruvate. Carboxyphosphate decomposes within the active site into Pi and CO2, the latter combining with the enolate to form oxalacetate. Besides carboxylation, PEPC catalyzes a HCO3 --dependent hydrolysis of PEP to yield pyruvate and Pi. Post-translational regulation of PEPC occurs by a phosphorylation/dephosphorylation cascade in vivo and by reversible enzyme oligomerization in vitro. The interrelation between phosphorylation and oligomerization of the enzyme is not clear. PEPC-protein kinase (PEPC-PK), the enzyme responsible for phosphorylation of PEPC, has been studied extensively while only limited information is available on the protein phosphatase 2A capable of dephosphorylating PEPC. The C4 ppc was cloned and expressed in Escherichia coli as well as tobacco. The transformed E. coli produced a functional/phosphorylatable C4 PEPC and the transgenic tobacco plants expressed both C3 and C4 isoforms. Site-directed mutagenesis of ppc indicates the importance of His138, His579 and Arg587 in catalysis and/or substrate-binding by the E. coli enzyme, Ser8 in the regulation of sorghum PEPC. Important areas for further research on C4 PEPC are: mechanism of transduction of light signal during photoactivation of PEPC-PK and PEPC in leaves, extensive use of site-directed mutagenesis to precisely identify other key amino acid residues, changes in quarternary structure of PEPC in vivo, a high-resolution crystal structure, and hormonal regulation of PEPC expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029380
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  • 15
    Electronic Resource
    Electronic Resource
    A retinoic acid-inducible skin-specific gene (RIS-1/psoriasin): molecular cloning and analysis of gene expression in human skinin vivo and cultured skin cellsin vitro (1994)
    Springer
    Molecular biology reports 20 (1994), S. 75-83 
    Details
    ISSN: 1573-4978
    Keywords: retinoic acid ; skin ; differential hybridization ; cloning ; keratinocytes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A retinoic acid (RA) inducible skin-specific gene transcript (RIS-1) was isolated by differential hybridization screening of a RA-treated human skin cDNA library. The library was constructed from pooled RNA derived from normal adult human skin treated with alltrans-RA for 4 h (n=6) and 12 h (n=6)in vivo. RIS-1 cDNA corresponded to a 0.6 kb transcript that was barely detectable in normal adult human skin but was significantly induced by 8 h in RA-treated compared to vehicle-treated skin (range 1.1–3.6 fold). Prolonged RA treatment for up to 24 h further increased relative RIS-1 mRNA levels by 1.3–5.5 fold. HPLC analysis of the RA content of 0.1% RA-treated skinin vivo revealed significant levels at 6 h (18.8–120.6 ng RA/g wet weight tissue; approximately 240 nM), immediately preceding the time point at which the increased RIS-1 mRNA level was first seen. This concentration of RA also induced the mRNA levels for cellular RA binding protein II (1.6–19 fold), a marker of RA activity in human skin. RIS-1 mRNA was detected by Northern and dot blotting only in normal skin but not in any other normal human tissues examined, indicating a tissue-specific pattern of gene expression. RIS-1 transcripts were detected at very low levels in untreated cultured human epidermal keratinocytes, while no expression was seen in dermal fibroblasts and melanocytes, the other major cell types in skin. Southern analysis of human and mouse DNA indicated the existence of evolutionarily conserved sequences for RIS-1 between these two species. The polypeptide sequence derived from the partial RIS-1 cDNA was found to be identical to the calcium binding domain found in ‘psoriasin’, a gene whose expression appears to be increased in the skin of psoriasis patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00996356
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  • 16
    Electronic Resource
    Electronic Resource
    Cloning and molecular analysis of structural genes involved in flavonoid and stilbene biosynthesis in grape (Vitis vinifera L.) (1994)
    Springer
    Plant molecular biology 24 (1994), S. 743-755 
    Details
    ISSN: 1573-5028
    Keywords: anthocyanins ; cDNA cloning ; flavonoids ; gene expression ; genomic organization ; stilbenes ; Vitis vinifera L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genes involved in flavonoid and stilbene biosynthesis were isolated from grape (Vitis vinifera L.). Clones coding for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydoxylase (F3H), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX) and UDP glucose:flavonoid 3-O-glucosyl transferase (UFGT), were isolated by screening a cDNA library, obtained from mRNA from seedlings grown in light for 48 h using snapdragon (Antirrhinum majus) and maize heterologous probes. A cDNA clone coding for stilbene synthase (StSy) was isolated by probing the library with a specific oligonucleotide. These clones were sequenced and when the putative products were compared to the published amino acid sequence for corresponding enzymes, the percentages of similarity ranged from 65% (UFGT) to 90% (CHS and PAL). The analysis of the genomic organization and expression of these genes in response to light shows that PAL and StSy genes belong to large multigene families, while the others are present in one to four copies per haploid genome. The steady-state level of mRNAs encoded by the flavonoid biosynthetic genes as determined in young seedlings is coordinately induced by light, except for PAL and StSy, which appear to be constitutively expressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029856
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  • 17
    Electronic Resource
    Electronic Resource
    Low-temperature-responsive barley genes have different control mechanisms (1994)
    Springer
    Plant molecular biology 24 (1994), S. 879-888 
    Details
    ISSN: 1573-5028
    Keywords: barley ; cold acclimation ; gene expression ; low temperature genes ; nuclear run-on transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several low-temperature-responsive (LTR) genes from barley have been shown to have high steady-state transcript levels. Run-on transcription was used to determine the control of expression of these LTR genes. Six of these are shown to be transcriptionally regulated (blt 4/9, blt 101, blt 1015, blt 63, blt 49, blt 410) whilst three are post-transcriptionally regulated (blt 14, blt 411, blt 801). Two transcriptionally regulated genes (blt 4/9 and blt 101) and one post-transcriptionally regulated gene (blt 14) have been used in expression studies. The time course for the appearance and decay of these transcripts is given. Initial appearance and steady-state levels of individual transcripts have different temperature characteristics but no single gene correlates with the cold acclimation response. We suggest that these different response profiles may represent a means of fine-tuning the low-temperature response. One gene, blt 4/9, also accumulated high steady-state levels of transcript in response to drought and a nutrient stress. However, only drought has an acclimating effect on barley plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014442
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  • 18
    Electronic Resource
    Electronic Resource
    Gene expression of nitrite reductase in Scots pine (Pinus sylvestris L.) as affected by light and nitrate (1994)
    Springer
    Plant molecular biology 25 (1994), S. 449-457 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; light ; nitrate ; nitrite reductase ; Pimus sylvestris L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A partial cDNA clone (PSnir) encoding the C-terminal region of nitrite reductase was isolated from a λgt 11 library of the gymnospermPimus sylvestris (L.). Nucleotide sequence analysis showed that PSnir contains a reading frame encoding 105 amino acid residues. The amino acid sequence revealed a homology to NiR of 63–68% to dicotyledoneous and of 57–59% to monocotyledoneous species. The protein region implicated to be involved in binding of the prosthetic group is highly conserved between the NiR of the gymnosperm and of angiosperms. In all organs (cotyledonary whorls, hypocotyls, roots) the pattern of NiR gene expression in response to nitrate and light is the same at the level of transcript accumulation and at the enzyme level. This suggests that regulation of NiR gene expression in the Scots pine seedling is predominantly at the level of transcript accumulation. The highest NiR appearance was observed in roots and hypocotyls. In the cotyledonary whorls only small amounts of NiR were found. In roots and hypocotyls the accumulation of NiR mRNA and the appearance of NiR protein is mainly controlled by nitrate, whereas the regulation of NiR gene expression in the whorls is strongly affected by light and the inducive effect of nitrate is only weak.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043873
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  • 19
    Electronic Resource
    Electronic Resource
    A phenylalanine ammonia-lyase gene from melon fruit: cDNA cloning, sequence and expression in response to development and wounding (1994)
    Springer
    Plant molecular biology 26 (1994), S. 473-479 
    Details
    ISSN: 1573-5028
    Keywords: Cucumis melo ; melon ; phenylalanine ammonia-lyase ; gene expression ; ripening ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phenylalanine ammonia-lyase (PAL) is the first enzyme of phenylpropanoid biosynthesis involved in the synthesis of a multiplicity of plant natural products. We have isolated and characterized a nearly fulllength cDNA clone (pmPAL-1) corresponding to a melon fruit (Cucumis melo L. var. reticulatus) gene coding for a protein which is highly similar to PAL from other lants. Melon fruit PAL is transcriptionally induced both in response to fruit ripening and wounding. PAL gene expression follows the kinetics of expression of the ethylene biosynthetic genes during fruit development. In contrast, ethylene biosynthetic genes show different induction kinetics compared to PAL expression in response to wounding. Similar results have been found for two other genes coding for enzymes involved in flavonoid biosynthesis (chalcone synthase, CHS; chalcone isomerase, CHI). Our results imply that regulation of defense gene expression in melon is a co-ordinated process in response to both ethylene and an ethylene-independent wound signal.
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    URL: http://dx.doi.org/10.1007/BF00039557
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    Triticum aestivum puroindolines, two basic cystine-rich seed proteins: cDNA sequence analysis and developmental gene expression (1994)
    Springer
    Plant molecular biology 25 (1994), S. 43-57 
    Details
    ISSN: 1573-5028
    Keywords: cDNA sequence ; cystine-rich proteins ; gene expression ; puroindolines ; tryptophan-rich domain ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From a mid-maturation seed cDNA library we have isolated cDNA clones encoding two Triticum aestivum puroindolines. Puroindoline-a and puroindoline-b, which are 55% similar, are basic, cystine-rich and tryptophan-rich proteins. Puroindolines are synthezised as preproproteins which include N- and C-terminal propeptides which could be involved in their vacuolar localization. The mature proteins have a molecular mass of 13 kDa and a calculated isoelectric point greater than 10. A notable feature of the primary structure of puroindolines is the presence of a tryptophan-rich domain which also contains basic residues. A similar tryptophan-rich domain was found within an oat seed protein and a mammalian antimicrobial peptide. The ten cysteine residues of puroindolines are organized in a cysteine skeleton which shows similarity to the cysteine skeleton of other wheat seed cystine-rich proteins. Northern blot analysis showed that puroindoline genes are specifically expressed in T. aestivum developing seeds. No puroindoline transcripts as well as no related genes were detected in Triticum durum. The identity of puroindolines to wheat starch-granule associated proteins is discussed as well as the potential role of puroindolines in the plant defence mechanism.
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    URL: http://dx.doi.org/10.1007/BF00024197
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    Characterization of a cDNA from Arabidopsis thaliana encoding a potential thiol protease whose expression is induced independently by wilting and abscisic acid (1994)
    Springer
    Plant molecular biology 25 (1994), S. 259-270 
    Details
    ISSN: 1573-5028
    Keywords: abscisic acid ; Arabidopsis thaliana ; gene expression ; mutants ; signal transduction ; stress ; thiol protease ; wilting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sequence and expression characteristics are described of a wilt-inducible gene in Arabidopsis thaliana. A 1494 encodes a potential thiol protease whose mRNA accumulates rapidly in shoot tissue upon the loss of turgor. A1494 mRNA levels peaked after ca. 4 h and declined thereafter. Dehydration also induced rapid biosynthesis of the phytohormone abscisic acid (ABA), which continued for at least 9 h. Exogenous ABA induced the accumulation of A1494 mRNA, with kinetics similar to those after wilting. Rehydration of wilted shoots led to a rapid decline in the content of both ABA and A1494 mRNA. Wilting and ABA independently induced A1494 expression as evidenced by the effects of ABA and wilting on the ABA-deficient aba-1 and ABA-insensitive abi-1 and abi-3 genotypes. A1494 mRNA was not detectable in aba-1 shoots but accumulated rapidly after either wilting or ABA treatment, whereas the shoot ABA content was increased only by ABA treatment. ABA had no effect on A1494 mRNA levels in the abi-1 and abi-3 mutants but wilting did result in enhanced A1494 expression. Heat shock had only a minor effect on A1494 mRNA levels, whereas exposure to low temperature resulted in substantial accumulation of A1494 mRNA in wild-type shoots. However, this latter response, unlike that to drought, was mediated exclusively via ABA synthesis as demonstrated by the lack of A1494 mRNA accumulation in cold-treated aba-1 shoots.
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    URL: http://dx.doi.org/10.1007/BF00023242
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    Calcium and calcium-binding proteins in the nucleus (1994)
    Springer
    Molecular and cellular biochemistry 135 (1994), S. 79-88 
    Details
    ISSN: 1573-4919
    Keywords: calcium ; nucleus ; calpain ; calmodulin ; cell division ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Calcium has long been known to play a role as a key cytoplasmic second messenger, but until relatively recently its possible involvement in nuclear signal transduction and the regulation of nuclear events has not been extensively studied. Evidence revealing the presence of transmembrane nuclear Ca2+ gradients and a variety of intranuclear Ca2+ binding proteins has fueled renewed interest in this key ion and its involvement in cell-cycle timing and division, gene expression, and protein activation. This review will offer an overview of the current state of knowledge and theory regarding calcium orchestration of nuclear functions and events and discuss possible future directions in this field of study.
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    URL: http://dx.doi.org/10.1007/BF00925963
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    Expression of calcium-binding protein regucalcin mRNA in rat liver is stimulated by calcitonin: The hormonal effect is mediated through calcium (1994)
    Springer
    Molecular and cellular biochemistry 136 (1994), S. 43-48 
    Details
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; rat liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The involvement of a hypocalcemic hormone calcitonin (CT) in the expression of hepatic Ca2+-binding protein regucalcin mRNA was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb). A single oral administration of calcium chloride (100 mg Ca/100 g body weight) to rats induced a remarkable increase in the serum calcium concentration and a corresponding elevation of the liver calcium content during 120 min after the administration. Thyroparathyroidectomy (TPTX) did not cause a significant increase in the liver calcium content after calcium administration. Hepatic regucalcin mRNA level was markedly elevated by calcium administration; the level was about 180% of controls at 60 min after the administration. This increase was completely abolished by TPTX. A single subcutaneous administration of CT (synthetic eel CT; 25–100 MRC mU/100 g) to TPTX rats received oral administration of calcium (100 mg/100 g) produced a remarkable increase in hepatic regucalcin mRNA levels; the level was about 280% of controls with the dose of 25 MRC mU CT/100 g. The present finding suggests that the expression of hepatic mRNA is stimulated by CT, and that the hormonal effect is mediated through Ca2+ in rat liver.
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    URL: http://dx.doi.org/10.1007/BF00931603
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    Expression of nitrate assimilation related genes in Chlamydomonas reinhardtii (1994)
    Springer
    Plant molecular biology 24 (1994), S. 185-194 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; light/nitrate regulation ; nitrate reductase ; nitrate transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mRNA accumulation pattern of the Chlamydomonas reinhardtii nitrate assimilation-related gene cluster has been elucidated. In ammonium-grown wild-type cells, nit-1 (nitrate reductase, NR), nar-1, nar-2 and nar-3 (nitrate transporter) genes showed very similar kinetics of expression when transferred to nitrate medium. Transcripts of all these genes accumulated transiently in ammonium-grown wild-type cells after a one-hour incubation in nitrogen-free medium, and practically disappeared at about 2 hours. Mutant strains lacking functional nitrate reductase showed similar accumulation kinetics of these transcripts during both nitrate induction and derepression in nitrogen-free media. In contrast to the other nar transcripts, that nar-4, a gene sharing similar sequences with nar-3, accumulated in small amounts in wild-type cells, and only increased after a long nitrate induction period. Nitrate and light showed a strong positive effect on the accumulation of nit-1 gene transcripts. Acetate as a carbon source allowed accumulation of nit-1 mRNA in the dark, indicating the existence of interactions between light and carbon metabolism in nit-1 gene expression. Our data strongly suggest that NR negatively autoregulates its own expression and that of nar genes.
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    URL: http://dx.doi.org/10.1007/BF00040584
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    Expression of one of the members of the Arabidopsis chaperonin 60β gene family is developmentally regulated and wound-repressible (1994)
    Springer
    Plant molecular biology 24 (1994), S. 195-202 
    Details
    ISSN: 1573-5028
    Keywords: plant transformation ; chaperonin 60β ; β-glucuronidase ; wound repression ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To study the pattern of gene regulation of the plastid chaperonin 60β gene family a chimaeric gene was constructed fusing the 5′-flanking region of the chaperonin 60β B3 gene to the β-glucuronidase reporter gene. Histochemical and fluorometric analysis of the GUS activity present in transgenic plants harbouring this gene construct showed that the B3 promoter is expressed in leaves, stem, petioles and several flower tissues. The pattern of cell type-specific expression in stems and flowers was found to be developmentally regulated. Expression of the B3 promoter was found not to be heat-inducible, but highly repressed by wounding. The rapid decay in GUS activity upon wounding indicates that, at least under some physiological conditions, the gene product of this reporter gene is not as stable as has been previously thought.
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    URL: http://dx.doi.org/10.1007/BF00040585
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    Tissue-specific expression of the large ATP synthase gene cluster in spinach plastids (1994)
    Springer
    Plant molecular biology 25 (1994), S. 369-376 
    Details
    ISSN: 1573-5028
    Keywords: ATP synthase ; chloroplast ; gene expression ; plastid ; RNA stability ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plastids present in different tissues may vary morphologically and functionally, despite the fact that all plastids within the same plant contain identical genomes. This is achieved by regulation of expression of the plastid genome by tissue-specific factors, the mechanisms of which are not fully understood. The proton translocating ATP synthase/ATPase is a multisubunit complex composed of nine subunits, six encoded in the plastid and three in the nucleus. We have investigated the tissue-specific expression of the large ATP synthase gene cluster in spinach (Spinacia oleracea). This gene cluster encodes four of the six plastid-encoded ATP synthase genes. Transcript abundance, transcriptional activity, and transcript stability were investigated relative to gene dosage in root plastids and in stem, leaf, and flower chloroplasts. All three of these factors display significant tissue-specific variation. It was intriguing to discover that, although transcript abundance normalized to gene dosage varies in each tissue, transcript abundance as a proportion of the entire plastid RNA population in each tissue is not significantly different. Thus it appears that in these tissues the variation in transcription and stability of transcripts derived from the large ATP synthase gene cluster balances to yield an equivalent proportion of these transcripts in the plastid RNA population. Expression of this gene cluster in photosynthetic as well as non-photosynthetic tissues may facilitate the plasticity of structure and function which is characteristic of plastids.
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    URL: http://dx.doi.org/10.1007/BF00043866
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    The Chlorella virus adenine methyltransferase gene promoter is a strong promoter in plants (1994)
    Springer
    Plant molecular biology 26 (1994), S. 85-93 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; monocot cells ; promoter strength ; transient expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An upstream region isolated from a eukaryotic algal virus adenine methyltransferase gene was tested for promoter function in plants. Fusion of this region to the chloramphenicol acetyltransferase reporter gene resulted in significantly higher expression than fusion with the cauliflower mosaic virus 35S promoter. Strong levels of expression were also found in electroporated monocot plant cells. The promoter activity in transgenic tobacco plants showed tissue-specific expression. Leaves had the highest expression followed by stems and flowers. The promoter activity was not detected in root tissue. Environmental cues, such as light, and the phytohormones auxin and cytokinines had no effect on the promoter's expression. This promoter might be utilized to achieve high levels of expression of introduced genes in higher plants.
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    URL: http://dx.doi.org/10.1007/BF00039522
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    Expression of the tobacco Tnt1 retrotransposon promoter in heterologous species (1994)
    Springer
    Plant molecular biology 26 (1994), S. 393-402 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; Brassica napus ; gene expression ; Nicotiana tabacum ; retrotransposon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of the tobacco (Nicotiana tabacum) retrotransposon Tntl has previously been shown to be strongly regulated and driven from the 5′ long terminal repeat (LTR). We report here that the Tntl LTR can promote activity of the β-glucuronidase (GUS) reporter gene in two heterologous species of the Brassicaceae family, namely rapessed (Brassica napus) and Arabidopsis thaliana. The translational LTR-GUS fusion was active in transient expression studies performed with tobacco and rapeseed protoplasts, indicating that the LTR sequences are recognized in heterologous species. Our results also showed that Tntl LTR-promoted GUS expression in transgenic Arabidopsis is strongly regulated, and that, in contrast to tobacco, hormonal activation plays a significant role in the expression of the Tntl LTR in Arabidopsis. LTR sequences were shown to be more effective than the CaMV 35S enhancer region in transient expression studies performed with tobacco or rapessed protoplasts; and substitution of the LTR sequences upstream from the major transcriptional start with the CaMV 35S enhancer region gave high levels of expression in transgenic tobacco and Arabidopsis leaves, suggesting that a Tntl element with similar substitutions in its 5′ LTR might be suited for gene-tagging experiments in heterologous species.
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    URL: http://dx.doi.org/10.1007/BF00039548
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    Structure and promoter analysis of an ABA- and stress-regulated barley gene, HVA1 (1994)
    Springer
    Plant molecular biology 26 (1994), S. 617-630 
    Details
    ISSN: 1573-5028
    Keywords: ABA ; barley ; gene expression ; Hordeum vulgare ; phylogeny ; stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A single-copy barley gene, HVA1, encoding a class 3 late embryogenesis-abundant protein, can be induced by either treatment with abscisic acid (ABA) or by stress conditions such as drought, cold, heat and salinity. We have isolated an HVA1 genomic clone containing about 400 bp of 5′-upstream sequence, a single 109 bp intron, and the full coding sequence. Linker scan mutagenesis and transient expression studies were used to test the function of four HVA1 promoter elements conserved in ABA-responsive genes. Mutations in two of these elements, the C box and the putative ABRE 1 (ABA-responsive element) containing an ACGT core, resulted in no significant change in transcription level or ABA induction. In contrast, mutations of the other two elements, putative ABRE 2 & 3 cause the level of transcription to drop to 10–20% of that obtained with the wild-type promoter indicating that the high level of expression of HVA1 is dependent on both pABRE 2 & 3. Interestingly, despite their low level of expression, the mutated promoters still gave more than 20-fold induction in response to ABA treatment. We suggest that the ABA induction of barley HVA1 gene is governed by a complex consisting of pABRE 2 & 3 working together to regulate the absolute level of expression, and either of these elements or a possible third element may regulate ABA inducibility. Phylogenetic analysis by parsimony indicates that the barley HVA1 and wheat pMA2005 sequences share a recent common ancester. These two genes are closely related to the carrot Dc3 and cotton D-7 genes with which they share a similar structural gene organization.
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    Vascular expression of the grp1.8 promoter is controlled by three specific regulatory elements and one unspecific activating sequence (1994)
    Springer
    Plant molecular biology 26 (1994), S. 747-756 
    Details
    ISSN: 1573-5028
    Keywords: activating sequence ; gene expression ; glycine-rich protein ; tobacco ; vascular expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The bean grp1.8 full-length promoter is specifically active in vascular tissue during normal development of tobacco. Deletion of a negative regulatory element resulted in ectopic activity of the promoter in cortical cells of hypocotyls, roots and stems. A 169 bp fragment (−205 to −36) of the grp1.8 promoter conferred vascular-specific expression to CaMV 35S minimal promoters whereas a 141 bp fragment (−205 to −64) strongly activated these minimal promoters both in vascular and cortical cells. These experiments defined a new regulatory element (VSE) that is essential for vascular-specific expression and is located between −64 and −36. The 141 bp grp1.8 promoter sequence had enhancer-like properties as it was active in both orientations. A 24 bp sequence (bp −119 to −96, corresponding to the SE1 regulatory element) enhanced expression from several minimal promoters strongly but unspecifically, whereas a 26 bp sequence (−98 to −73, corresponding to the RSE regulatory element) induced vascular-specific expression. Thus, the grp1.8 promoter is regulated by a combinatorial mechanism that can integrate the action of different, non-additively acting regulatory elements into vascular-specific expression.
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    URL: http://dx.doi.org/10.1007/BF00013759
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    Environmental stress-mediated differential 3′ end formation of chloroplast RNA-binding protein transcripts (1994)
    Springer
    Plant molecular biology 26 (1994), S. 833-849 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; RNA stability regulation ; chloroplast RNA-binding protein (cRBP) ; environmental stress ; Mesembryanthemum crystallinum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report the characterization of transcripts from the halophyte, Mesembryanthemum crystallinum, encoding a protein with high homology to chloroplast RNA-binding proteins (cRBP). In this plant chloroplast-related functions are largely protected against salt stress. cRBP transcripts are derived from a single gene, Mc32crbp, although three size classes of polyadenylated mRNAs are detected. Transcription rate and steady state amounts of mRNA are developmentally regulated and light controlled with strong transcriptional activity as functional chloroplasts are established, and with lower maintenance activity thereafter. Upon salt stress, the rate of transcription decreases, although transcript levels increase. Accompanying stress, a change in the distribution of transcript size classes is observed as the longest transcript with an untranslated 3′ end of 381 nucleotides increases relative to transcripts with shorter 3′ ends. The long transcript is characterized by the presence of five sequence elements in the 3′-untranslated region that are present in cRBP mRNAs from a variety of plants, although not all elements are found in each mRNA. The results may indicate a mechanism by which mRNA levels of constitutively light-regulated genes may be modulated without enhanced transcription in response to environmental cues.
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    URL: http://dx.doi.org/10.1007/BF00028852
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    Gibberellins: perception, transduction and responses (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1529-1555 
    Details
    ISSN: 1573-5028
    Keywords: gibberellin ; growth ; development ; perception ; receptor ; gene expression ; signal transduction ; response mutant ; calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00016489
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    Regulation of an Arabidopsis oleosin gene promoter in transgenic Brassica napus (1994)
    Springer
    Plant molecular biology 25 (1994), S. 193-205 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis ; embryo ; gene expression ; oleosin ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Progressive deletions of the 5′-flanking sequences of an Arabidopsis oleosin gene were fused to β-glucuronidase (GUS) and introduced into Brassica napus plants using Agrobacterium-mediated transformation. The effect of these deletions on the quantitative level of gene expression, organ specificity and developmental regulation was assessed. In addition, the influence of abscisic acid (ABA), jasmonic acid (JA), sorbitol and a combined ABA/sorbitol treatment on gene expression was investigated. Sequences that positively regulate quantitative levels of gene expression are present between −1100 to −600 and −400 to −200 of the promoter. In addition, sequences present between −600 and −400 down-regulate quantitative levels of expression. In transgenic B. napus plants, the oleosin promoter directs seed-specific expression of GUS which is present at early stages of seed development and increases throughout seed maturation. Sequences present between −2500 and −1100 of the promoter are involved in modulating the levels of expression at early stages of embryo development. Histochemical staining of embryos demonstrated that expression is uniform throughout the tissues of the embryo. Sequences involved in the response to ABA and sorbitol are present between −400 and −200. The induction of GUS activity by a combined ABA/sorbitol treatment is additive suggesting that ABA is not the sole mediator of osmotically induced oleosin gene expression. A response to JA was only observed when the oleosin promoter was truncated to −600 suggesting that the reported effect of JA on oleosin gene expression may be at a post-transcriptional level.
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    Over-production of the D1 protein of photosystem II reaction centre in the cyanobacterium Synechococcus sp. PCC 7942 (1994)
    Springer
    Plant molecular biology 26 (1994), S. 709-721 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; photosynthesis ; protein turnover ; psbA ; tac promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The unicellular cyanobacterium Synechococcus sp. PCC 7942 has three psbA genes encoding two different forms of the photosystem II reaction centre protein D1 (D1:1 and D1:2). The level of expression of these psbA genes and the synthesis of D1:1 and D1:2 are strongly regulated under varying light conditions. In order to better understand the regulatory mechanisms underlying these processes, we have constructed a strain of Synechococcus sp. PCC 7942 capable of over-producing psbA mRNA and D1 protein. In this study, we describe the over-expression of D1:1 using a tac-hybrid promoter in front of the psbAI gene in combination with lacI Q repressor system. Over-production of D1:1 was induced by growing cells for 12 h at 50 μmol photons m-2 s-1 in the presence of 40 or 80 μg/ml IPTG. The amount of psbAI mRNA and that of D1:1 protein in cells grown with IPTG was three times and two times higher, respectively. A higher concentration of IPTG (i.e., 150 μg/ml) did not further increase the production of the psbAI message or D1:1. The over-production of D1:1 caused a decrease in the level of D1:2 synthesised, resulting in most PSII reaction centres containing D1:1. However, the over-production of D1:1 had no effect on the pigment composition (chlorophyll a or phycocyanin/number of cells) or the light-saturated rate of photosynthesis. This and the fact that the total amounts of D1 and D2 proteins were not affected by IPTG suggest that the number of PSII centres within the membranes remained unchanged. From these results, we conclude that expression of psbAI can be regulated by using the tac promoter and lacI Q system. However, the accumulation of D1:1 protein into the membrane is regulated by the number of PSII centres.
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    A dehydrin cognate protein from pea (Pisum sativum L.) with an atypical pattern of expression (1994)
    Springer
    Plant molecular biology 26 (1994), S. 805-816 
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    ISSN: 1573-5028
    Keywords: Dehydrin ; gene expression ; pea (Pisum sativum L.) ; cognate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dehydrins are a family of proteins characterised by conserved amino acid motifs, and induced in plants by dehydration or treatment with ABA. An antiserum was raised against a synthetic oligopeptide based on the most highly conserved dehydrin amino acid motif, the lysine-rich block (core sequence KIKEK-LPG). This antiserum detected a novel M r 40 000 polypeptide and enabled isolation of a corresponding cDNA clone, pPsB61 (B61). The deduced amino acid sequence contained two lysine-rich blocks, however the remainder of the sequence differed markedly from other pea dehydrins. Surprisingly, the sequence contained a stretch of serine residues, a characteristic common to dehydrins from many plant species but which is missing in pea dehydrin. The expression patterns of B61 mRNA and polypeptide were distinctively different from those of the pea dehydrins during seed development, germination and in young seedlings exposed to dehydration stress or treated with ABA. In particular, dehydration stress led to slightly reduced levels of B61 RNA, and ABA application to young seedlings had no marked effect on its abundance. The M r 40 000 polypeptide is thus related to pea dehydrin by the presence of the most highly conserved amino acid sequence motifs, but lacks the characteristic expression pattern of dehydrin. By analogy with heat shock cognate proteins we refer to this protein as a dehydrin cognate.
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    Detection of immunologically related Kunitz and Bowman-Birk proteinase inhibitors expressed during potato tuber development (1994)
    Springer
    Plant molecular biology 26 (1994), S. 961-969 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; Kunitz-type proteinase inhibitor ; potato (Solanum tuberosum, L.) ; soybean C-II inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Antiserum against a potato Kunitz-type proteinase inhibitor (PKPI) expressed in Escherichia coli was produced. In immunoblotting assays of proteins from potato tubers cultured in vitro, three proteins reacted to the antiserum, two of 20 kDa and one of 10 kDa. Their N-termini were sequenced. While the 20 kDa proteins showed 59 and 90% identity to PKPI, the 10 kDa one had 65% identity to soybean C-II proteinase inhibitor. Characterization of the temporal expression of these proteins showed that both could be detected from 10 days after induction of tuberization (DAI) in vitro, but the times when maximum amounts of PKPI and 10 kDa protein could be detected were different, corresponding to 22 and 32 DAI, respectively. The amounts of these proteins decreased in the following stages, and no positive reaction of the antiserum with mature tuber proteins could be found. The 20 kDa proteins were also detected in early stages of development of potato tubers grown in the field, indicating that these proteins are expressed during normal tuber development, and differ from the PKPIs reported previously.
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    Isolation and characterization of two β-tubulin cDNA clones from rice (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1975-1979 
    Details
    ISSN: 1573-5028
    Keywords: β-tubulin ; cDNA ; rice ; monocot ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two cDNA clones encoding two different β-tubulins, RTUB-1 and RTUB-2, were isolated from a rice cDNA library and their nucleotide sequences were analyzed. The deduced amino acid sequences showed amino acid sequence identity between 92% and 97% with other plant β-tubulins. Southern blot analysis using gene-specific and coding-region probes suggested that β-tubulins in rice are encoded by multigene families. The two cDNA clones represent two subfamilies of rice tubulins. RTUB-1 and RTUB-2, consisting of 3 to 4 genes and a single gene, respectively. The transcript levels of RTUB-1 and RTUB-2 genes were higher in actively elongating tissues such as etiolated shoot tissues and light-grown root tissues of four-day old seedlings.
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    Acclimation of photosynthetic proteins to rising atmospheric CO2 (1994)
    Springer
    Photosynthesis research 39 (1994), S. 413-425 
    Details
    ISSN: 1573-5079
    Keywords: elevated CO2 ; gene expression ; Rubisco ; rbcL ; rbcS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this review we discuss how the photosynthetic apparatus, particularly Rubisco, acclimates to rising atmospheric CO2 concentrations (ca). Elevated ca alters the control exerted by different enzymes of the Calvin cycle on the overall rate of photosynthetic CO2 assimilation, so altering the requirement for different functional proteins. A decreased flux of carbon through the photorespiratory pathway will decrease requirements for these enzymes. From modeling of the response of CO2 uptake (A) to intracellular CO2 concentration (ci) it is shown that the requirement for Rubisco is decreased at elevated ca, whilst that for proteins limiting ribulose 1,5 bisphosphate regeneration may be increased. This balance may be altered by other interactions, in particular plasticity of sinks for photoassimilate and nitrogen supply; hypotheses on these interactions are presented. It is speculated that increased accumulation of carbohydrate in leaves developed at elevated ca may signal the ‘down regulation’ of Rubisco. The molecular basis of this ‘down regulation’ is discussed in terms of the repression of photosynthetic gene expression by the elevated carbohydrate concentrations. This molecular model is then used to predict patterns of acclimation of perennials to long term growth in elevated ca.
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    UV-B damage and protection at the molecular level in plants (1994)
    Springer
    Photosynthesis research 39 (1994), S. 475-489 
    Details
    ISSN: 1573-5079
    Keywords: DNA repair ; flavonoids ; gene expression ; oxidative stress ; photosynthesis ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Influx of solar UV-B radiation (280–320 nm) will probably increase in the future due to depletion of stratospheric ozone. In plants, there are several targets for the deleterious UV-B radiation, especially the chloroplast. This review summarizes the early effects and responses of low doses of UV-B at the molecular level. The DNA molecules of the plant cells are damaged by UV due to the formation of different photoproducts, such as pyrimidine dimers, which in turn can be combatted by specialized photoreactivating enzyme systems. In the chloroplast, the integrity of the thylakoid membrane seems to be much more sensitive than the activities of the photosynthetic components bound within. However, the decrease of mRNA transcripts for the photosynthetic complexes and other chloroplast proteins are among very early events of UV-B damage, as well as protein synthesis. Other genes, encoding defence-related enzymes, e.g., of the flavonoid biosynthetic pathway, are rapidly up-regulated after commencement of UV-B exposure. Some of the cis-acting nucleotide elements and trans-acting protein factors needed to regulate the UV-induced expression of the parsley chalcone synthase gene are known.
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    The 24kDa outer envelope membrane protein from spinach chloroplasts: molecular cloning, in vivo expression and import pathway of a protein with unusual properties (1994)
    Springer
    Plant molecular biology 25 (1994), S. 167-177 
    Details
    ISSN: 1573-5028
    Keywords: Spinacia oleracea ; chemical cleavage ; gene expression ; polymerase chain reaction ; protein transport ; SDS-PAGE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The 24 kDa outer envelope membrane protein of spinach chloroplasts (omp24) represents a major constituent of this membrane. Sequences of tryptic and endoprotease Glu-C peptides derived from omp24 allowed the design of oligonucleotides which were used to generate a DNA fragment by polymerase chain reaction using spinach cDNA as template. This fragment served as a probe to screen a cDNA library for a full-length clone of the omp24 coding sequence. The protein predicted from the complete sequence only has 148 amino acids and a molecular mass of 16294 Da. It is an acidic protein (calculated isoelectric point 4.8) with a high content of proline residues. Expression of the coding sequence in Escherichia coli and characterization of the purified recombinant protein produced revealed that the overestimation of its molecular mass by SDS-PAGE (ca. 25 kDa) is due to its abnormal amino acid composition. Despite its rather low hydrophobicity (polarity index 49%), omp24 appears to be deeply embedded in the outer membrane. Insertion of omp24 into the membrane proceeds almost independently of surface receptors or targeting sequence but, in contrast to other known outer envelope membrane proteins, is stimulated by ATP.
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    Isolation and characterization of two tightly linked catalase genes from castor bean that are differentially regulated (1994)
    Springer
    Plant molecular biology 25 (1994), S. 507-516 
    Details
    ISSN: 1573-5028
    Keywords: castor bean (Ricinus communis) ; catalase gene ; gene expression ; germination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two catalase genes,cat1 andcat2, have been isolated from the castor bean genome. They were located in the same direction on a chromosome at a distance of 2.4 kb,cat1 being on the downstream side ofcat2. The two genes contained introns at the same positions except that one of the 7 introns incat1 is missing incat2 and the corresponding introns differed in size and sequence between the two genes. The translated regions of the two genes had the same number of nucleotides and exhibited 81.3% nucleotide sequence identity. In addition to introns, the nucleotide sequences of the 5′-and 3′-flanking regions are highly divergent between the two genes. In etiolated seedlings,cat1 mRNA was present abundantly in endosperms and cotyledons and only in a small amount in roots. Thecat1 mRNA could not be detected in hypocotyls. By contrast,cat2 mRNA is most abundant in hypocotyls and roots, while endosperms and cotyledons contained only low levels ofcat2 mRNA. Although neithercat1 norcat2 mRNA could be detected in dry seeds, both mRNAs showed temporal accumulation in the endosperm in response to germination. These results suggest that expression of two tightly linked catalase genes of castor bean,cat1 andcat2, are differentially regulated during development.
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    Characterization of four new β-tubulin genes and their expression during male flower development in maize (Zea mays L.) (1994)
    Springer
    Plant molecular biology 24 (1994), S. 295-315 
    Details
    ISSN: 1573-5028
    Keywords: β-tubulin ; microtubules ; maize ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four different β-tubulin coding sequences were isolated from a cDNA library prepared from RNA from maize seedling shoots. The four genes (designated tub4, tub6, tub7 and tub8) represented by these cDNA clones together with the tub1 and tub2 genes reported previously encode six β-tubulin isotypes with 90–97.5% amino acid sequence identity. Results from phylogenetic analysis of 17 β-tubulin genes from monocot and dicot plant species indicated that multiple extant lines of β-tubulin genes diverged from a single precursor after the appearance of the two major subfamilies of α-tubulin genes described previously. Hybridization probes from the 3′ non-coding regions of six β-tubulin clones were used to quantify the levels of corresponding tubulin transcripts in different maize tissues including developing anthers and pollen. The results from these dot blot hybridization experiments showed that all of the β-tubulin genes were expressed in most tissues examined, although each gene showed a unique pattern of differential transcript accumulation. The tub1 gene showed a high level of transcript accumulation in meristematic tissues and almost no accumulation in the late stages of anther development and in pollen. In contrast, the level of tub4 transcripts was very low during early stages of male flower development but increased markedly (more than 100 times) during the development of anthers and in pollen. Results from RNAse protection assays showed that this increased hybridization signal resulted from expression of transcripts from one or two genes closely related to tub4. The tub4-related transcripts were not present in shoot tissue. Transcripts from the tub2 gene accumulated to very low levels in all tissues examined, but reached the highest levels in young anthers containing microspore mother cells. RNAse protection assays were used to measure the absolute levels of α- and β-tubulin transcripts in seedling shoot and in pollen. The α-tubulin gene subfamily I genes (tua1, tua2, tua4) contributed the great majority of α-tubulin transcripts in both shoot and pollen. Transcripts from the β-tubulin genes tub4, tub6, tub7, and tub8 were predominant in shoot, but were much less significant than the tub4-related transcripts in pollen.
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    Structural and functional analysis of an Opaque-2-related gene from sorghum (1994)
    Springer
    Plant molecular biology 24 (1994), S. 515-523 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; b-ZIP motif ; seed storage proteins ; trans-acting factors ; transcription factors ; transcriptional regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Opaque-2 (O2) gene from maize encodes a transcriptional activator of the b-ZIP class. We have isolated and characterized a gene from sorghum, related in sequence to the O2 gene from maize. A single copy of the gene is present in sorghum. Both genomic and cDNA sequences of the O2-related sorghum gene were determined. The sequence is highly homologous to maize O2 both in the promoter and in the coding region. The most closely related sequences contain the b-ZIP domain with only 11 amino acid substitutions in a total of 122 residues. In transient expression assays, the sorghum O2-related coding sequence, expressed from a CaMV 35S promoter, activates expression from the maize b-32 promoter as effectively as that obtained with the maize O2 sequence.
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    Cloning of two gibberellin-regulated cDNAs from Arabidopsis thaliana by subtractive hybridization: expression of the tonoplast water channel, γ-TIP, is increased by GA3 (1994)
    Springer
    Plant molecular biology 24 (1994), S. 603-615 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; dwarf mutant ; gene expression ; gibberellin ; subtractive hybridization ; tonoplast intrinsic protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Arabidopsis ga1 mutant has very low levels of endogenous, active gibberellins and thus has an extreme dwarf phenotype; application of GA3 induces stem elongation and flower development. To test the hypothesis that GA action in this system involves changes in gene expression, we have cloned mRNAs whose abundance changes following GA application. A subtraction cloning scheme for the isolation of differentially regulated cDNAs was established, involving hybridization of single-stranded cDNA to biotinylated mRNA. cDNA populations enriched up to 150-fold in GA-regulated sequences were produced and cDNA libraries generated. Screening of these libraries has isolated two clones that identify mRNAs of ca. 1100 and 750 bases whose abundance is markedly increased 24 h after GA application. One of these clones encodes the vegetative form of the Arabidopsis tonoplast intrinsic protein (γ-TIP), a water channel protein, the expression of which has recently been shown to be correlated with regions of cell expansion. The second clone is expressed only in the inflorescence and encodes a proline- and glycine-rich protein that may be a cell wall component.
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    Meristem-specific gene expression directed by the promoter of the S-phase-specific gene, cyc07, in transgenic Arabidopsis (1994)
    Springer
    Plant molecular biology 24 (1994), S. 863-878 
    Details
    ISSN: 1573-5028
    Keywords: cell cycle ; gene expression ; meristem ; promoter analysis ; transgenic Arabidopsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genomic clone for the cyc07 gene, which is expressed specifically at the S phase during the cell cycle in synchronous cultures of periwinkle (Catharanthus roseus) cells, was isolated. Determination of the nucleotide sequence of the clone revealed that the cyc07 gene consists of seven exons separated by six introns. Genomic Southern analysis indicated that the cyc07 gene is present as a single copy per haploid genome in periwinkle. Expression of related genes was detected in a wide range of other plants. Transgenic Arabidopsis plants were generated that expressed the gene for β-glucuronidase (GUS) under the control of the promoter of the cyc07 gene. The tissue-specific pattern of expression directed by the promoter was investigated by analysis of GUS activity. Histochemical tests demonstrated that 589 bp of the 5′-upstream sequence of the cyc07 gene could direct specifical expression of the GUS reporter gene in meristematic tissues in transgenic plants. The spatial pattern of expression directed by the promoter was closely correlated with meristematic activity and cell proliferation, suggesting an association between the function of the cyc07 gene and cell proliferation.
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    Structure of genes that encode isozymes of aspartate aminotransferase in Panicum miliaceum L., a C4 plant (1994)
    Springer
    Plant molecular biology 26 (1994), S. 723-734 
    Details
    ISSN: 1573-5028
    Keywords: aspartate aminotransferase ; C4 photosynthesis ; gene expression ; gene structure ; isozyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cytosolic and mitochondrial isozymes of aspartate aminotransferase (AspAT) function in the C4 photosynthetic cycle in NAD-malic enzyme-type C4 plants and are expressed at high levels in mesophyll cells and bundle sheath cells, respectively. We constructed a genomic library from Panicum miliaceum, a NAD-malic enzyme-type C4 plant, and cloned the genes for these isozymes. The sequence of the cloned gene for cytosolic AspAT spans 7800 bp and consists of 12 exons. The sequence of the cloned gene for mitochondrial AspAT spans 9000 bp and consists of 10 exons. The results of primer-extension analysis suggest that transcription may be initiated from multiple adjacent sites. Both genes have significant GC-rich regions around the site of initiation of transcription, and these regions showed no CpG suppression. The 5′-flanking regions of both genes include several short sequences similar to the regulatory elements found in other genes for components of the photosynthetic machinery. In particular, the cytosolic AspAT gene contains sequences similar to nuclear protein-binding sites in other mesophyll-expressed C4 photosynthetic genes and the mitochondrial AspAT gene contains elements for light-sensitive and constitutive expression of a bundle sheath-expressed gene. The results of Southern analysis indicated that there are at least two genes that encode each isozyme in the genome of P. miliaceum. A comparison of nitron-insertion positions between AspAT genes of plants and animals revealed that several introns are located at identical positions. On the basis of a phylogenetic tree among AspATs and tyrosine aminotransferase, we have shown that the introns of aminotransferase genes antedate the divergence of eubacteria, archaebacteria, and eukaryotes.
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    Expression of engineered antibodies in plant cells (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1023-1030 
    Details
    ISSN: 1573-5028
    Keywords: immunoglobulin genes ; gene expression ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00040685
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    A method for examining expression of homologous genes in plant polyploids (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1065-1071 
    Details
    ISSN: 1573-5028
    Keywords: Brassica ; polyploid ; gene expression ; RT-PCR ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One of the essential issues regarding evolution of polyploid species is how duplicate genes are expressed. Most studies on gene expression in polyploids have been based on isozyme analyses; RNA analysis has not been widely used partially due to difficulties in distinguishing homologous transcripts which usually have the same length and similar or almost identical sequences. In this study, a method combining RT-PCR with RFLP was used to analyze transcripts of homologous genes in natural and synthetic Brassica amphidiploids. Sequences coding for several known genes were selected and used to synthesize gene-specific primers. Total RNAs were used as templates for RT-PCR to amplify homologous transcripts in three diploid parental species, three cultivated amphidiploid species and six synthetic amphidiploids. For each gene, initial PCR products amplified in all species had identical length; however, homologous transcripts in the diploid and amphidiploid species could be distinguished after digesting the PCR products with restriction enzymes. Preliminary results based on three genes indicated that both transcripts from the diploid parents were expressed in the synthetic and natural amphidiploids. This study represents the first application of RT-PCR and RFLP analysis to investigate expression of homologous genes in higher plants. The technique is a sensitive, simple and efficient method for distinguishing homologous transcripts in a mixed RNA population and can be applied to many types of studies on expression of homologous genes.
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    Molecular cloning of the Arabidopsis thaliana sedoheptulose-1,7-biphosphatase gene and expression studies in wheat and Arabidopsis thaliana (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1191-1200 
    Details
    ISSN: 1573-5028
    Keywords: Calvin cycle genes ; gene expression ; SBPase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here the isolation and nucleotide sequence of genomic clones encoding the chloroplast enzyme sedoheptulose-1,7-bisphosphatase (SBPase) from Arabidopsis thaliana. The coding region of this gene contains eight exons (72–76 bp) and seven introns (75–91 bp) and encodes a polypeptide of 393 amino acids. Unusually, the 5′ non-coding region contains two additional AUG codons upstream of the translation initiation codon. A comparison of the deduced Arabidopsis and wheat SBPase polypeptide sequences reveals 78.6%, identity. Expression studies showed that the level of SBPase mRNA in Arabidopsis and wheat is regulated in a light-dependent manner and is also influenced by the developmental stage of the leaf. Although the Arabidopsis SBPase gene is present in a single copy, two hybridizing transcripts were detected in some tissues, suggesting the presence of alternate transcription start sites in the upstream region.
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    Coordinated expression of five tropomyosin isoforms and β-actin in astrocytes treated with dibutyryl cAMP and cytochalasin D (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 28 (1994), S. 303-316 
    Details
    ISSN: 0886-1544
    Keywords: cytoskeleton ; cell culture ; gene expression ; Northern blot ; serum-induction ; rat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytochalasin D and dBcAMP cause cultured astrocytes to change from flat cells to retrated process-bearing cells. F-actin was present throughout cells stimulated with dBcAMP for 16 h, whereas cytochalasin D caused F-actin to form massive aggregates at the tips of the cell processes. The two drugs differently regulated the expression of both β-actin and tropomyosin genes in astrocytes cultured in the presence or absence of serum: dBcAMP caused down-regulation and cytochalasin D caused up-regulation. Northern blot analyses indicated that: (1) serum deprivation halved the concentration of all tropomyosin transcripts (TM-1, TM-2, TM-4, TMBr-1, TMBr-2). Serum induced TM-4 via transcriptional activation, independent of protein synthesis, (2) dBcAMP induced down-regulation of β-actin (-50%) and tropomyosin transcripts (-35 to 52%) even in the presence of serum. The concentration of profilin mRNA decreased in dBcAMP-reactive astrocytes (-46%). The decrease in β-actin mRNA concentration was not blocked by cycloheximide, whereas down-regulation of tropomyosin transcripts was completely reversed when protein synthesis was inhibited, and (3) cytochalasin D induced an increase in the concentration of tropomyosin transcripts (+ 69 to 185%) which was cumulative with serum stimulation. Cytochalasin D induction of both β-actin and TM-4 operated through transcriptional activation, independent of protein synthesis.The production of all tropomyosin transcripts examined here were strictly coordinated with β-actin expression in serum-, dBcAMP- and cytochalasin D-treated astrocytes. This indicates that the differential expression of tropomyosin isoforms occurring during astrocyte maturation is due to more complex regulation than that involved in serum- or cAMP-stimulated astrocytes. © 1994 Wiley-Liss, Inc.
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    Modeling the regulation of bacterial genes producing proteins that strongly influence growth (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 242-257 
    Details
    ISSN: 0006-3592
    Keywords: genetic regulation ; gene expression ; transcriptional regulation ; translational regulation ; RNA polymerase ; rpoBc ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical method for comparing the performance of rival models of bacterial genetic regulation is presented. The particukar difficulties involved in describing the regulated synthesis of proteins that strongly influence cell growth are identiied, and the method is specifically designed to treat such cases. The method employs a mathematical description of intrinsic perturbations occurring during exponential growth to test the performance of regulatory models. Specific models of transcriptional and translational regulation are inserted into a general gene-expression framework in order to determine their control responses. Applying thhis approach to examine the regulation of RNA polymerase synthesis in Eschericia coli provides support for the hypothesis that rpoB translation is regulated by cooperative binding of multiple RNA polymerase molecules to the mRNA. The framework is of a sufficiently general form that the method can be used to study mechanisms involved in controlling synthesis of any bacterial protein. © 1994 John Wiley & Sons, Inc.
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    Recombinant protein expression in aDrosophila cell line: comparison with the baculovirus system (1994)
    Springer
    Cytotechnology 15 (1994), S. 139-144 
    Details
    ISSN: 1573-0778
    Keywords: Baculovirus ; cell culture ; Drosophila ; gene expression ; insect cell ; metallothionein promoter ; recombinant protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In this report, we compare two different expression systems: baculovirus/Sf9 and stable recombinantDrosophila Schneider 2 (S2) cell lines. The construction of a recombinant S2 cell line is simple and quick, and in batch fermentations the cells have a doubling time of 20 hours until reaching a plateau density of 20 million cells/ml. Protein expression is driven by theDrosophila Metallothionein promoter which is tightly regulated. When expressed in S2 cells, the extracellular domain of human VCAM, an adhesion molecule, is indistinguishable from the same protein produced by baculovirus-infected Sf9 cells. Additionally, we present data on the expression of a seven trans-membrane protein, the dopamine D4 receptor, which has been successfully expressed in both systems. The receptor integrates correctly in the S2 membrane, binds [3H]spiperone with high affinity and exhibits pharmacological characteristics identical to that of the receptor expressed in Sf9 and mammalian cells. The general implications for large scale production of recombinant proteins are discussed.
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    Carbohydrate binding activities ofBradyrhizobium japonicum: IV. Effect of lactose and flavones on the expression of the lectin, BJ38 (1994)
    Springer
    Glycoconjugate journal 11 (1994), S. 363-370 
    Details
    ISSN: 1573-4986
    Keywords: lectin ; gene expression ; cell-cell adhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract BJ38 is a galactose/lactose-specific lectin (M r ∼ 38000) found at one pole ofBradyrhizobium japonicum. It has been implicated in mediating the adhesion of the bacteria to soybean roots, leading to the establishment of a nitrogen-fixing symbiosis. When the ligand lactose is added to cultures of the bacteria for at least 1 h prior to harvesting the cells for BJ38 isolation, the yield of the protein was found to be elevated in a dose-dependent fashion. Half maximal stimulation was observed at ∼ 50 µm; the effect was saturated at ∼ 1mm, where a 10-fold higher yield of BJ38 was obtained. Saccharides with a lower affinity for BJ38 than lactose yielded a correspondingly smaller induction effect when compared at a concentration of 1mm. The higher level of BJ38 induced by lactose is also manifested by an elevated amount of BJ38 detectable at the cell surface and by a higher number ofB. japonicum cells adsorbed onto soybean cells. Surprisingly, the induction of BJ38 expression seen with lactose was also observed with certain, but not all, flavonoids that induce thenod genes of the bacteria; genistein mimicked the induction observed with lactose, whereas luteolin failed to stimulate BJ38 production.
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    Complementation of an alcohol dehydrogenase-deficientNicotiana plumbaginifolia mutant by transformation with theArabidopsis thaliana Adh gene (1994)
    Springer
    Transgenic research 3 (1994), S. 376-387 
    Details
    ISSN: 1573-9368
    Keywords: alcohol dehydrogenase ; Arabidopsis thaliana ; functional complementation ; gene expression ; Nicotiana plumbaginifolia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An alcohol dehydrogenase-deficient (ADH) mutant ofNicotiana plumbaginifolia, selected on the basis of ethanol resistance, was restored for ADH activity by transformation with anAdh gene fromArabidopsis thaliana expressed under the control of its own promoter or the CaMV 35S promoter. The expression in various organs (seed, root, leaf and pollen) was analysed at the protein and RNA levels as well as byin situ detection of ADH activity. The analysis of spatial and temporal regulation of theA. thaliana Adh gene expression suggests that ADH expression is controlled at the transcriptional level.
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    Design and application of antisense oligonucleotides in cell culture,in vivo, and as therapeutic agents (1994)
    Springer
    Cellular and molecular neurobiology 14 (1994), S. 557-568 
    Details
    ISSN: 1573-6830
    Keywords: antisense oligonucleotides ; gene expression ; pharmacology ; drug design ; cell cultures ; brain research
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Synthetic oligonucleotides can inhibit the expression of a gene in a sequence specific manner on the transcriptional and translational level. These molecules are usually referred to as antisense oligonucleotides. 2. Antisense mediated inhibition of gene expression is a valuable tool to analyze the function of a genein vivo and can also be used for therapeutic gene suppression. 3. A number of factors such as the mode of action, specificity, chemistry, and pharmacology must be carefully considered for the design and successful application of antisense oligonucleotides. 4. Assay systems and controls must be chosen as to assure that the observed biological effects of antisense oligonucleotides do in fact reflect the result of a specific gene inhibition. 5. This article critically discusses these factors in view of the literature and our own experience with a wide range of cell types and animal models, targeting different genes. The emphasis is on the use of phosphorothioate oligodeoxynucleotides in cell cultures,in vivo, and as potential drugs.
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    Powdery mildew resistance in Aegilops tauschii coss. and synthetic hexaploid wheats (1994)
    Springer
    Genetic resources and crop evolution 41 (1994), S. 151-158 
    Details
    ISSN: 1573-5109
    Keywords: Triticum aestivum ; Aegilops tauschii (syn. Ae. squarrosa) ; Erysiphe graminis f. sp. tritici resistance genes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A collection of 400 Ae. tauschii (syn. Ae. squarrosa) Coss. accessions were screened for powdery mildew resistance based on the response patterns of 13 wheat cultivars/lines possessing major resistance genes to nine differential mildew isolates. 106 accessions showed complete resistance to all isolates, and 174 accessions revealed isolate-specific resistance, among which were 40 accessions exhibiting an identical response pattern as wheat cultivar ‘Ulka/*8Cc’ which is known to possess resistance gene Pm2. Expression of both complete and isolate-specific resistance from Ae. tauschii was observed in some synthetic hexaploid wheats derived from four mildew susceptible T. durum Desf. parents, each crossed with five to 38 resistant diploid Ae. tauschii accessions. Synthetic amphiploids involving different combinations of T. durum and Ae. tauschii generally showed a decrease in resistance compared with that expressed by the Ae. tauschii parental lines.
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    Tissue specific expression of an α-skeletal actin-lacZ fusion gene during development in transgenic mice (1994)
    Springer
    Transgenic research 3 (1994), S. 59-66 
    Details
    ISSN: 1573-9368
    Keywords: α-actin ; transgenic mice ; gene expression ; muscle ; embryos ; lacZ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic mice carrying a chimaeric transgene containing 730 bp of the 5′-flanking sequences and the entire first intron of the rat α-skeletal actin gene fused to thelacZ reporter gene have been produced by microinjection. ThelacZ reporter gene was used to verify the suitability of using the rat α-actin promoter elements to target expression of genes of agricultural and therapeutic value exclusively to skeletal and heart muscle cells and fibres of transgenic mice. Expression of the transgene indicates a tightly regulated developmental and muscle specific control of the rat α-skeletal actin gene, making it a useful promoter for gene targeting to muscle tissues. The cells destined to form muscle tissues in these transgenic mice are readily visualized in intact embryos by staining for β-galactosidase activity, making them a suitable animal model for studying the origin and development of skeletal and cardiac muscle tissues.
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    URL: http://dx.doi.org/10.1007/BF01976028
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    Functional integrity of metallothionein genes in testicular cell lines (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 55 (1994), S. 486-495 
    Details
    ISSN: 0730-2312
    Keywords: Metallothionein ; gene expression ; Leydig cell ; Sertoli cell ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The presence and inducibility of the major cadmium (Cd) chelating protein metallothionein (MT) in testicular cells has been controversial. In this study, the induction and production of MT in testicular cells were studied using mouse Leydig and Sertoli cell lines. Metal accumulation was studied by subjecting the cells to increasing levels of Cd. The presence of transcription factors for MT synthesis was analyzed by transfecting the cells with a reporter gene under the control of the MT promoter. The dose- and time-dependent induction of MT were conducted by Northern analyses. Expression of MT genes occurred in both Leydig and Sertoli cells. To avoid cross hybridization of the MT probe with mRNAs encoding testicular metal binding proteins and to investigate the integrity of MT mRNA, isoMT mRNA identification and primer extension experiments were performed. Those studies show that the induced mRNA indeed encodes MT. The biosynthesis of MT was confirmed by following 35S-cysteine incorporation into the protein. Finally, cadmium tolerance of testicular cells is compared with that of fibroblast cells. By these studies, we conclude that the MT genes are functional and inducible in testicular cells. © 1994 Wiley-Liss, Inc.
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    Alterations in cellular gene expression without changes in nuclear matrix protein content (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 56 (1994), S. 502-509 
    Details
    ISSN: 0730-2312
    Keywords: MCF10A ; nuclear matrix ; gene expression ; ras ; actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cell metabolism and function are modulated in part by cell and nuclear shape. Nuclear shape is controlled by the nuclear matrix, the RNA-protein skeleton the nucleus, and its interactions with cytoskeletal systems such as intermediate filaments and actin microfilaments. The nuclear matrix plays an important role in cell function and gene expression because active genes are bound to the nuclear matrix whereas inactive genes are not. It is unknown, however, how genes move on and off the matrix, and whether these events require compositional protein changes, i.e., alterations in protein content of the nuclear matrix, or other, more subtle alterations and/or modificatins. The purpose of this investigation was to begin to determine how nuclear matrix protein composition is related to gene expression. We demonstrate that gene expression can change without apparent changes in the protein composition of the nuclear matrix in MCF10A breast epithelial cells.
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    URL: http://dx.doi.org/10.1002/jcb.240560410
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    Dual role of osteoblastic proenkephalin derived peptides in skeletal tissues (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 55 (1994), S. 334-339 
    Details
    ISSN: 0730-2312
    Keywords: analgesia ; bone development ; gene expression ; opioids ; tissue regeneration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Proenkephalin encodes a group of small peptides with opiate-like activity, the endogenous opioids, known to function as neurohormones, neuromodulators, and neurotransmitters. Recently, we have demonstrated that in addition to its abundance in fetal brain tissue, proenkephalin is highly expressed in nondifferentiated mesodermal cells of developing fetuses. We identified the skeletal tissues, bone, and cartilage as major sites of proenkephalin expression. To examine the possibility that proenkephalin is involved in bone development we have studied the expression of this gene in bone-derived cells, its modulation by bone active hormones, and the effects of enkephalin-derived peptides on osteoblastic phenotype. Our studies revealed that osteoblastic cells synthesize high levels of proenkephalin mRNA which are translated, and the derived peptides are secreted. Reciprocal interrelationships between osteoblast maturation and proenkephalin expression were established. These results together with our observations demonstrating inhibitory effects of proenkephalin-derived peptides on osteoblastic alkaline phosphatase activity, strongly support the notion that proenkephalin is involved in bone development. A different direction of research by other investigators has established the capability of the opioid system in the periphery to participate in the control of pain. On the basis of these two lines of observation, we would like to present the following hypothesis: The potential of embryonic skeletal tissue to synthesize proenkephalin-derived peptides is retained in the adult in small defined undifferentiated cell populations. This potential is realized in certain situations requiring rapid growth, such as remodeling or fracture repair. We suggest that in these processes, similarly to the situation in the embryo, the undifferentiated dividing cells produce the endogenous opioids. In the adult these peptides may have a dual function, namely participating in the control of tissue regeneration and in the control of pain. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jcb.240550310
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    Cellular and clinical perspectives on skeletal insulin-like growth factor I (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 55 (1994), S. 328-333 
    Details
    ISSN: 0730-2312
    Keywords: insulin-like growth factor I ; transcriptional control ; posttranscriptional control ; gene expression ; insulin-like growth factor binding proteins ; osteoblast ; bone formation ; osteoporosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Insulin-like growth factor (IGF) I, a polypeptide synthesized by skeletal cells, is presumed to act as an autocrine regulator of bone formation. IGF I stimulates bone replication of preosteoblastic cells and enhances the differentiated function of the osteoblast. The synthesis of skeletal IGF I is regulated by systemic hormones, most notably parathyroid hormone and glucocorticoids, as well as by locally produced factors, such as prostaglandins and other skeletal growth factors. Whereas hormones and growth factors regulate IGF I synthesis, the exact level of regulation has not been established and may involve both transcriptional and posttranscriptional mechanisms. The IGF I gene contains six exons, and both exon 1 and 2 contain transcription initiation sites. Extrahepatic tissues, including bone, express exon 1 transcripts, and regulation of the exon 1 promoter activity in osteoblasts is currently under study. It is apparent that the regulation of IGF I gene transcription as well as the regulation of mRNA stability is complex and tissue specific. It is possible that abnormalities in skeletal IGF I synthesis or activity play a role in the pathogenesis of bone disorders. In view of its important anabolic actions in bone, it is tempting to postulate the use of IGF I for the treatment of disorders characterized by decreased bone mass. An alternative could be the stimulation of the local production of IGF I in bone. © 1994 Wiley-Liss, Inc.
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    Localization of erythropoietin mRNA in the rat kidney by polymerase chain reaction (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 54 (1994), S. 239-246 
    Details
    ISSN: 0730-2312
    Keywords: gene expression ; microdissection ; nephron segments ; endothelial cells ; in situ hybridization ; erythropoiesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Erythropoietin (Epo) is a glycoprotein secreted by kidney cells which plays an important role in the regulation of erythropoiesis. Localization of the Epo production by immunohistochemical studies and in situ hybridization has not been definitively established and is still a matter of controversy. Epo and glyceraldehyde 3-dehydrogenase (GAPDH) mRNA levels were determined in total RNA isolated from control and CoCl2-treated rats using a coupled reverse transcriptase/polymerase chain reaction method (RT/PCR). As indicated by the amount of amplification product, Epo mRNA levels were several-fold higher in CoCl2-treated rat kidney. In contrast, GAPDH mRNA levels were similar in control and CoCl2-treated rats. This RT/PCR method was also used to assess the level of Epo and GAPDH mRNA in microdissected nephron segments. All nephron segments tested lacked any detectable levels of Epo mRNA in either control or CoCl2-treated rats. On the other hand, peritubular cells (capillary fraction: afferent/efferent arteriole, vasa recta) were the only cells where the Epo mRNA was detected. Using a specific primer for GAPDH, the RT/PCR method could identify GAPDH mRNA in all microdissected nephron segments where the Epo mRNA was not expressed. Thus, a combination of microdissected nephron segments and RT/PCR enabled us to detect GAPDH mRNA populations in all nephron segments, whereas the failure to detect Epo mRNA in all segments but the capillary fraction, is due to the specific and localized expression of the Epo gene to this fraction.
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    URL: http://dx.doi.org/10.1002/jcb.240540212
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    Nuclear architecture supports integration of physiological regulatory signals for transcription of cell growth and tissue-specific genes during osteoblast differentiation (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 55 (1994), S. 4-15 
    Details
    ISSN: 0730-2312
    Keywords: nucleus ; gene expression ; cell growth ; osteoblast ; nucleosome ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: During the past several years it has become increasingly evident that the three-dimensional organization of the nucleus plays a critical role in transcriptional control. The principal theme of this prospect will be the contribution of nuclear structure to the regulation of gene expression as functionally related to development and maintenance of the osteoblast phenotype during establishment of bone tissue-like organization. The contributions of nuclear structure as it regulates and is regulated by the progressive developmental expression of cell growth and bone cell related genes will be examined. We will consider signalling mechanisms that integrate the complex and interdependent responsiveness to physiological mediators of osteoblast proliferation and differentiation. The focus will be on the involvement of the nuclear matrix, chromatin structure, and nucleosome organization in transcriptional control of cell growth and bone cell related genes. Findings are presented which are consistent with involvement of nuclear structure in gene regulatory mechanisms which support osteoblast differentiation by addressing four principal questions: (1) Does the representation of nuclear matrix proteins reflect the developmental stage-specific requirements for modifications in transcription during osteoblast differentiation? (2) Are developmental stage-specific transcription factors components of nuclear matrix proteins? (3) Can the nuclear matrix facilitate interrelationships between physiological regulatory signals that control transcription and the integration of activities of multiple promoter regulatory elements? (4) Are alterations in gene expression and cell phenotypic properties in transformed osteoblasts and osteosarcoma cells reflected by modifications in nuclear matrix proteins? There is a striking representation of nuclear matrix proteins unique to cells, tissues as well as developmental stages of differentiation, and tissue organization. Together with selective association of regulatory molecules with the nuclear matrix in a growth and differentiation-specific manner, there is a potential for application of nuclear matrix proteins in tumor diagnosis, assessment of tumor progression, and prognosis of therapies where properties of the transformed state of cells is modified. It is realistic to consider the utilization of nuclear matrix proteins for targeting regions of cell nuclei and specific genomic domains on the basis of developmental phenotypic properties or tissue pathology. © 1994 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/jcb.240550103
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    Signal transduction pathways mediating parathyroid hormone regulation of osteoblastic gene expression (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 55 (1994), S. 321-327 
    Details
    ISSN: 0730-2312
    Keywords: parathyroid hormone ; signal transduction ; osteoblasts ; cAMP ; gene expression ; activator protein-1 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Parathyroid hormone (PTH) plays a central role in regulation of calcium metabolism. For example, excessive or inappropriate production of PTH or the related hormone, parathyroid hormone related protein (PTHrP), accounts for the majority of the causes of hypercalcemia. Both hormones act through the same receptor on the osteoblast to elicit enhanced bone resorption by the osteoclast. Thus, the osteoblast mediates the effect of PTH in the resorption process. In this process, PTH causes a change in the function and phenotype of the osteoblast from a cell involved in bone formation to one directing the process of bone resorption. In response to PTH, the osteoblast decreases collagen, alkaline phosphatase, and osteopntin expression and increases production of osteocalcin, cytokines, and neutral proteases. Many of these changes have been shown to be due to effects on mRNA abundance through either transcriptional or post-transcriptional mechanisms. However, the signal transduction pathway for the hormone to cause these changes is not completely elucidated in any case. Binding of PTH and PTHrP to their common receptor has been shown to result in activation of protein kinases A and C and increases in intracellular calcium. The latter has not been implicated in any changes in mRNA of osteoblastic genes. On the other hand activation of PKA can mimic all the effects of PTH; protein kinase C may be involved in some responses. We will discuss possible mechanisms linking PKA and PKC activation to changes in gene expression, particularly at the nuclear level. © 1994 Wiley-Liss, Inc.
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    Synthese von ( - )-(Acetoxymethyl)(hydroxymethyl)methyl(phenyl)german [( - )-MePhGe(CH2OAc)(CH2OH)] durch eine Esterase-katalysierte Umesterung: Die erste enzymatische Synthese eines optisch aktiven Germans (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 639-642 
    Details
    ISSN: 0009-2940
    Keywords: Germane, optically active ; Biotransformation, stereoselective ; Transesterification, enzymatic ; Porcine liver esterase ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of ( - )-(Acetoxymethyl)(hydroxymethyl)methyl(phenyl)germane [( - )-MePhGe(CH2OAc)(CH2OH)] by an Esterase-Catalyzed Transesterification: the First Enzymatic Synthesis of an Optically Active GermaneThe prochiral germane MePhGe(CH2OH)2 (1) was synthesized by a six-step synthesis starting from GeCl4 (3) [3 → Cl2Ge(CH2Cl)2 (4) → Ph2Ge(CH2Cl)2 (5) → (CF3S(O)2O)PhGe(CH2Cl)2 (6) → MePhGe(CH2Cl)2 (7) → MePhGe(CH2OAc)2 (8) → 1]. Reaction of 1 with Ac2O/NEt3 (molar ratio 1: Ac2O = 1:1) gave the racemic germane rac-MePhGe(CH2OAc)(CH2OH) (rac-2). Stereoselective transesterification of 1 with vinyl acetate (acetate source and solvent), catalyzed by immobilized porcine liver esterase (PLE; E.C.-3.1.1.1), yielded the optically active germane ( - )-MePhGe(CH2OAc)(CH2OH) [( - )-2] (yield 57%, enantiomeric purity 50% ee).
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    URL: http://dx.doi.org/10.1002/cber.19941270409
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    Zur Bildung eines Fe2(CO)6-Komplexes mit (Boryloxy)allyl-Brücke (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 91-92 
    Details
    ISSN: 0009-2940
    Keywords: Boranes, amino(imino) ; Iron, tricarbonyl(butanone) ; Diiron, [(boryloxy)allyl]hexacarbonyl ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Formation of a Fe2(CO)6 Complex with a (Boryloxy)allyl BridgeThe amino(imino)borane Me3Si(tBu)N=B=NtBu (1) reacts with (benzylideneacetone)tricarbonyliron (2) in 1:2 molar ratio to give a 50% yield of the hexacarbonyldiiron complex 3 with a fly-over (boryloxy)allyl bridge, which crystallizes in the space group P21/c. The structure of 3 can be described as a pyramid with Fe(CO)3 at the apex and a non-planar pentagon [-Fe(CO)3-O(BXX′)-C(Me)-CH-C(Ph)-] [X = NHtBu, X′ = N(SiMe3)tBu] as the basis, but there is no bond between the apex and the O atom.
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    URL: http://dx.doi.org/10.1002/cber.19941270114
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    Bis(pentamethylcyclopentadienyl)methanol: Synthese, Struktur und Derivatisierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 107-112 
    Details
    ISSN: 0009-2940
    Keywords: Bis(pentamethylcyclopentadienyl)methanol ; Diels-Alder reaction, intramolecular ; Chloroformate, bis(pentamethylcyclopentadienyl)methanol ; Tosylate, bis(pentamethylcyclopentadienyl)methanol ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(pentamethylcyclopentadienyl)methanol: Synthesis, Structure, and DerivatizationBis(pentamethylcyclopentadienyl) ketone (1) reacts at low temperatures with LiAlH4 to form in good yields (pentamethylcyclopentadienyl)methanol (2) and its corresponding intramolecular Diels-Alder product 3 in a ca. 2:1 ratio. The alcohol 2 is separated from the tetracyclic compound 3 by crystallisation at -70°C from hexane/pyridine as pyridine adduct. The pyridine-free alcohol 2 is available by repeated dissolving of the adduct in hexane and removal of the volatile components in vacuo. The alcohol tends to intramolecular [4 + 2] cycloaddition even at room temperature with formation of 3. A derivatization of 2 is possible by deprotonation with alkyllithium compounds, which leads to the alcoholate 4, and subsequent treatment with phosgen and tosyl chloride, thus affording the chloroformate 6 and the tosylate 7, respectively, in good yields. The thermolabile tosylate 7 decomposes to pentamethylbenzene or, under basic conditions, to the pentacyclic compound 7.
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    URL: http://dx.doi.org/10.1002/cber.19941270118
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    Darstellung geeigneter Vorstufen zur Synthese von 16,16,16,17,17,17-Hexafluorretinalen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 145-149 
    Details
    ISSN: 0009-2940
    Keywords: Bis(trifluormethyl)butenal ; Retinoids ; β-Ionol ; Fluoro compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of Suitable Precursors for the Synthesis of 16,16,16,17,17,17-HexafluororetinalsCycloaddition reactions of (CF3)2C = CHCHO with butadiene or 1,3-pentadiene provide the corresponding cyclohexane derivatives 2, 3 and 4. Condensation of 3 with (C2H5O)2P-(O)CH2C(O)CH3 or of 2 with acetone in the presence of bases yields 5 and 7. While 5 reacts with CH2 = CHMgBr to give 6, treatment of 7 with diluted HCI provides 8. Compounds 7 and 8 proved to be not suitable as starting materials for the preparation of 16,16,16,17,17,17-hexafluororetinals. A better synthon is the diene 11. This is obtained in a threestep reaction starting from hexafluoroacetone and (C6H5)3P=CHC(O)CH3 to give 9 which on treatment with CH3MgI provides 10. Dehydration of 10 with 50% H2SO4 forms 11. In this reaction sequence byproduct 12 is formed presumably by addition of CF3C(O)CF3 to 9. At elevated temperatures under pressure 11 adds ethylene to form 13. Functionalization of 13 in 2-position is achieved by hydroboration/oxidation yielding 14 which is oxidized with pyridinium dichromate to 15. Oxidation and bromination reaction of 13 are described.
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    Zur Kenntnis der carbonylmethylenierenden Molybdän-Aluminium- und Wolfram-Aluminium-μ-methylen-Komplexe (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 127-135 
    Details
    ISSN: 0009-2940
    Keywords: Carbonyl olefination ; Molbydenum aluminium complexes, organo ; Tungsten aluminium complexes, organo ; Tebbe reagent ; Aluminium, molybdenum and tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organomolybdenum and Organotungsten Reagents, VI[1]. On the Carbonyl-Methylenating Molybdenum-Aluminium and Tungsten-Aluminium μ-Methylene ComplexesMoCl5, MoOCl3(THF)2, MoO2Cl2, (MeO)2MoCl3, (MeO)4MoCl, WOCl3(THF)2, and WOCl4 form carbonyl-methylenating complexes and 1-2 equiv. of CH4 by reacting with 2 equiv. of Me3Al. These thermolabile complexes are prepared in solution and differ in their properties (e.g. ability to transfer mostly more than 1 CH2 unit per Mo or W atom in carbonyl-olefinating processes; high sensitivity to water, no hydroxy ketone affinity) from the carbonyl-olefinating 1,3-dimetallacyclobutanes (M = Mo, W) and are believed to be mono- and bicyclic analogs (e.g. hypothic structures 3, 6-8) of the Tebbe reagent (1), containing Mo-μCH2 Al or W -μCH2 Al groups, respectively. Analogous complexes seem to be produced by treating MoOCl3(THF)2 with 2 Me2Zn or (MeO)2MoCl3 and (MeO)4MoCl with 2 MeMgBr in each case. Unlike the dimeric and, due to a Mo—Mo bond, diamagnetic Mo derivatives (Me—O)2MoCl3 and (MeO)4MoCl (according to 1H—NMR structure 9 or 10 and 11 or 12, respectively) the complexes obtained by the reactions (MeO)2MoCl3 + 2 Me3Al and (MeO)4MoCl + 2 Me3Al are paramagnetic, indicating the expected absence of a Mo—Mo bond. The 1H—NMR spectrum of the reaction mixture obtained by treating the MoVI derivative MoO2Cl2 with 2 Me3Al in THF shows various signals for μ—CH2 groups, whereas signals of t-CH2 ligands are missing (t = terminal). In analogy to 1 the carbonyl-olefinating activity of the Mo—Al and W—Al reagents is activated by the addition of 2 equiv. of HMPA. Treatment of PhCOCH2NEt2 (19) with {MoO2Cl2 + 2 Me3Al} leads to carbonyl olefination with formation of 20 and also to α-methylation with formation of PhCOCH(Me)-NEt2 (21), pointing to the intermediate formation of a t-CH2—Mo ligand. {MoO2Cl2 + 2 Me3Al + 2 HMPA} has found to be the best reagent for the carbonyl olefination of aldehydes, whereas {WOCl3(THF)2 + 2 Me3Al + 2 HMPA} was optimal for ketones. In 1:1 reactions both reagents normally give better yields than the Tebbe reagent. By applying (WOCl3(THF)2 + 2 Me3Al} and {MoO2Cl2 + 2 Me3Al} on ketones 16-18 an interesting neighbour group effect of electron donor atoms in the δ position to the keto group was observed.
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    Kleine Ringe, 79. Synthese und Eigenschaften neuer Silyl-substituierter Cyclobutadiene und Tetrahedrane (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 191-200 
    Details
    ISSN: 0009-2940
    Keywords: Diazo compounds ; Valence isomerization ; „Corset effect“ ; limits of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small Rings, 79[1].  -  Synthesis and Properties of Novel Silyl-Substituted Cyclobutadienes and TetrahedranesThe cyclobutadienes 2b, d as well as the corresponding tetrahedranes 3b, d have been prepared according to the “Masamune route” by starting from the diazo compounds 1b, d. Low-temperature 13C—NMR measurements of the cyclobutadienes 2a, b, d lead to the first exact values of the barrier heights in the interconversion of the two rectangular forms of the cyclobutadienes. Fluorodesilylation of 3d probably proceeds via tri-tert-butyltetrahedrane (3h) and cyclobutadiene 2h and finally yields diketone 18. Reaction of tetrahedrane 3d with LiAlH4 in boiling THF leads to tetrahedrane 3e, which is much less stable than all previously known tetrahedrane derivatives.
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    Relative Reactivities of Acetals and Ethers under Friedel-Crafts Conditions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 213-217 
    Details
    ISSN: 0009-2940
    Keywords: Alkylation ; Alkoxyalkylation ; Carboxonium ions ; Acetals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Competition experiments have been performed to determine the relative reactivities of acetals and ethers toward allyltrimethylsilane in the presence of catalytic amounts of BF3 OEt2. It is found that acetals R-CH(OMe)2 and their phenylogous p-anisyl ethers R-CH(p-MeOC6H4)(OMe) show very little differences in reactivity. The reactivity scales are employed to rationalize the results of Lewis acid-catalyzed additions of acetals and ethers to CC double bonds.
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    Gas-Phase Kinetics of the Pyrolysis of Some 3,3-Dimethyl-1-(trimethylsilyl)-cyclopropenes  -  Unexpected Product Distribution in the Cyclopropene Rearrangement (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 237-245 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopropenes, 3,3-dimethyl-1-trimethylsilyl-substituted ; Cyclopropene, isomerisation ; Gas-phase kinetics ; Ring opening ; Diradical intermediates ; Cyclopropylidene intermediates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase pyrolyses of 1,3,3-trimethyl-2-(trimethylsilyl)-cyclopropene (9), 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropeneTextReactantlog (A/s-1)Ea/kj mol-1(kcal mol-1)913.41 ± 0.22192.1 ± 2.5(45.9 ± 0.6)1013.54 ± 0.19184.4 ± 2.1(44.1 ± 0.5)1112.17 ± 0.38124.6 ± 3.1(29.8 ± 0.7)(10), and 3,3-dimethyl-1-(methylthio)-2-(trimethylsilyl)cyclopropene (11) have been studied, and the pressure-independent Arrhenius parameters listed in the table were obtained. All three rearrangements are homogeneous, first-order and unimolecular reactions. Rather surprisingly all reactions give the corresponding isomeric allenes as the main products. Amongst possible mechanisms discussed, 10 is proposed to react via a cyclopropylidene intermediate, whilst the results for 9 and 11 throw light on the relative importance of the diradical- and vinylcarbene-type intermediates produced by cyclopropene ring opening.
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    Graphical Abstract (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. A5 
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    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270139
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    Charge-Transfer-Komplexe von Metalldithiolenen, XIII. cis-trans-Photoisomerisierbare Viologene als redoxaktive Akzeptoren  - Synthese und elektrische LeitfähigkeitHerrn Prof. Dr. C. Krüger zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 287-294 
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    ISSN: 0009-2940
    Keywords: Metal dithiolenes ; Dipyridinioethylene dihalides ; Charge-Transfer complexes ; Electrical conductivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Charge-Transfer Complexes of Metal Dithiolenes, XIII[1]. - cis-trans-Photoisomerisable Viologens as Redoxactive Acceptors  -  Synthesis and Electrical ConductivityIon Pair Charge-Transfer (IPCT) complexes of the type [A2+[ML2]2-} (1a-f to 4a-f) are synthesized from dianionic metal dithiolenes [M = Ni, Zn, L = cis-1,2-dicyano-1,2-ethene-dithiolate (mnt2-), 2-thioxo-1,3-dithiol-4,5-dithiolate (dmit2-)] and dicationic viologens [A2+ = 4,4′-(1,2-ethenediyl)bis(1-alkylpyridinium)]. The acceptors can exist as cis/trans isomers and may have coordinating properties in the case of 1-cyanoalkyl groups. The IPCT bands are in the range of 500 to 1200 nm and their energy follows the Hush-Marcus relation. For the nickel complexes the reorganization energy amounts to 73, for the zinc compounds to 115 kJ/mol. As shown by X-ray analysis of {A2+[Ni(mnt)2]2-} (2d), A2+ = trans-4,4′-(1,2-ethenediyl)-bis[1-(3-cyanopropyl)pyridinium], the structure consists of stacks of alternating donors and acceptors with a typical plane-to-plane distance of 350 pm. There is no interaction between the cyano group of the acceptor and the nickel atom of the donor. The electrical conductivities of the nickel compounds are in the range of 5 · 10-6 to 3 · 10-11 Ω-1 cm-1, and the corresponding activation energies vary from 0.24 to 0.61 eV. For the dmit complexes these values agree well with the free activation enthalpy of the electron transfer reaction A2+ + [ML2]2- → A+ + [ML2]- calculated from the Hush-Marcus model. This suggests that charge carrier generation occurs by electron transfer. When a trans acceptor is replaced by its cis isomer in [A2+[NiL2]2-}, conductivity changes from 5 · 10-7 to 5 · 10-6 Ω-1 cm-1 and the activation energy from 0.43 to 0.24 eV, when L - dmit2- but stays at about 1 · 10-8 Ω-1 cm-1 for L = mnt2-.
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    Masthead (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19941270101
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    Nb4Te17I4, a New Pseudo One-Dimensional Solid-State Polytelluride (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 11-14 
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    ISSN: 0009-2940
    Keywords: Niobium iodide telluride ; Polytellurides ; Chain compounds, one-dimensional ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new ternary compound Nb4Te17I4 has been prepared and structurally characterized. It crystallizes in the monoclinic system, space group C2/c with unit-cell parameters a = 16.199(4), b = 8.128(2), c = 27.355(6) Å, β = 110.84(2)°, Z = 4. The structure consists of infinite one-dimensional niobium/tellurium chains running parallel to the crystallographic c direction. The chains are separated by iodine atoms. Short and long metal-metal distances alternate in the sequence of three consecutive short bonds ([d ≈ 3.1 - 3.2 Å) and one long (d = 4.268 Å) metal-metal separation. Each Nb atom is eight-coordinate. The composition of the chain is ∞11[(Nb5+)2(Nb4+)2(Te22-)4(Te32-)3(I-)4].
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    Synthese, Struktur und elektronische Eigenschaften von Cu0.69NbTe2 (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 15-21 
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    ISSN: 0009-2940
    Keywords: Copper niobium telluride ; Layer compounds ; Low-dimensional compounds ; Electrical properties ; Band structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis, Structure and Electronic Properties of Cu0.69NbTe2Cu0.69NbTe2 is obtained from the elements in a sealed quartz ampoule at 850°C. The structure of Cu0.69NbTe2 is related to the CdI2 type. The Cu atoms are disordered and situated in tetrahedral sites between the NbTe2 layers. The Nb atoms form zig-zag chains extending in one direction within the layers. This deformation of the Nb sublattice from trigonal symmetry is typical for CdI2 derivatives with formal electron counts close to d2 on the early transition metal. The magnetic susceptibility is temperature-independent between 4 K and 300 K (Pauli paramagnetism). Resistivity measurements confirm the metallic behavior of the compound. The crystal structure and the physical properties are in agreement with the results of tight-binding band-structure calculations.
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    Darstellung und Eigenschaften von S-(Trifluormethyl)polysulfanmonosulfonaten CF3SxSO2M [x = 1, M = OH, NH40O, 1/2 HgO2, (CH3)3SiO, (CH3)2N, NH2; x = 2, M = NH4O]Herrn Professor Reinhard Schmutzler zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 457-463 
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    ISSN: 0009-2940
    Keywords: (Trifluoromethyl)sulfane- and -disulfanesulfonic acids ; Mercury compounds ; (Trifluoromethyl)sulfanyl-disulfanyl-, and -sulfinylimine ; Arsenic compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Properties of S-(Trifluoromethyl)polysulfanemonosulfonates CF3SxSO2M [x=1, M = OH, NH4O, 1/2 HgO2, (CH3)2N, NH2; x=2, M = NH4O]*Hydrolysis of CF3SNSO with 2 equiv. of H2O provides [NH4][CF3SSO3] (1), which on treatment with chlorine gives CF3SCl and [NH4][ClSO3]. Trifluoromethyl thiosulfates are synthesized from Hg(SCF3)2 and ClSO2M [M = NH4O, (CH3)3SiO (2), (CH3)2N (3), NH2 (4)]. Insertion of SO3 into Hg(SCF3)2 provides Hg[CF3SSO2O]2 (6). Similarly, S-(trifluoromethyl)thiosulfuric acid (5) is obtained from CF3SH and SO3. New preparations for CF3SXNSO (x=1, 2) are described. These compounds are formed either from Hg(NSO)2 or (CH3)3SiNSO and CF3SxCl in good yields. CF3SSNSO (8) reacts with water to give [NH4][CF3SSSO3] (9). A 1:1 adduct (10) is obtained from CF3SNSO and AsF5. A preliminary X-ray structure investigation proved that AsF5 is coordinated to the oxygen atom. Some reactions of [NH4][CF3SSO3] and CF3SSO2OSi(CH3)3 are mentioned.
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    Funktionalisierte Tripod-Liganden: Synthese und Koordination von Tris[(diphenylphosphanyl)methyl]methan (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 501-506 
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    ISSN: 0009-2940
    Keywords: Tripod ligand synthesis ; Tripod iron trisacetonitrile complexes ; Tripod cobalt acetate complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Functionalized Tripod Ligands: Synthesis and Coordination of 1,1,1-Tris[(diphenylphosphanyl)methyl]methaneThe tripod ligand HC(CH2PPh2)3 (4) is easily available from the reaction of 1,3-dichloro-2-(chloromethyl)propane (3) with lithium diphenylphosphide. The ligand 4 itself and two of its coordination compounds, [(HC(CH2PPh2)3)Co(OOCMe)]+-[BPh4]- (5 · BPh4) and [(HC(CH2PPH2)3)Co(OOCMe)]2+ · 2[BF4]- [7 · (BF4)2] have been characterized by X-ray analyses. Coordination of 4 leads to an opening of the CH2—CH—CH2 bond angles (114° in 7 · (BF4)2 and 5 · BPh4 versus 111° in 4). This change in structure is reflected by the unusual low field shift of the methine hydrogen of 7 · (BF4)2 (δ = 3.90) in comparison with the corresponding signal of the free ligand 4 (δ = 1.53).
    Additional Material: 5 Ill.
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    Comparison of the Nucleophilicities of Alkynes and Alkenes. Quantitative Determination of the Nucleophilicities of Alkynes toward Carbenium Ions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 525-531 
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    ISSN: 0009-2940
    Keywords: Alkynes ; Alkenes ; Nucleophilicity ; Carbenium ions ; Vinyl cations ; Kinetics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relative reactivities of alkenes and alkynes toward diarylmethyl cations have been determined by direct rate measurements and by competition experiments in dichloromethane. At -70°C alkynes are found to be one to two orders of magnitude less reactive than analogously substituted alkenes (e.g. phenylacetylene/styrene), but the reactivity difference reduces strongly as the temperature is raised. The stereochemistry of the vinyl chlorides produced by addition of benzhydryl chlorides to alkynes is characterized.
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    Relative Reactivities of Alkyl Chlorides under Friedel-Crafts Conditions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 205-212 
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    ISSN: 0009-2940
    Keywords: Alkylation ; Allylation ; Carbenium ions ; Friedel-Crafts reactions ; Linear free energy relationships ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Competition experiments have been performed to determine the relative reactivities of 23 alkyl chlorides toward allyltrimethylsilane in the presence of catalytic amounts of ZnCl2.The krel scale spans over 11 orders of magnitude from 1-adamantyl chloride (least reactive) to bis(p-methoxyphenyl)methyl chloride (most reactive compound). A fair correlation between the alkylating ability and the SN1 reactivity in solvolysis reactions is found, thus providing a quantitative basis for our long-standing working hypothesis that Lewis acid-catalyzed additions of alkyl halides to CC multiple bonds only yield 1:1 products if the reactants ionize faster than the products. Trityl chlorides do not follow this correlation and are 105 times less reactive than predicted from their SN1 reactivities.
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    Zinc Complexes of Porphyrin-Quinone Cyclophanes: Syntheses, Structures and Electron-Transfer-Related Properties (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 231-236 
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    ISSN: 0009-2940
    Keywords: Zinc porphyrin complexes ; Porphyrin-quinone cyclophanes ; Photoinduced electron transfer ; Electron-transfer mechanism in metalloporphyrin-quinone cyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to increase the driving force for photoinduced electron-transfer reactions of porphyrin-quinone cyclophanes, the zinc complexes 3a-e and 4a-e were prepared from the corresponding cyclophanes of the 1 and 2 series. Electron-transfer-related properties like redox potentials and fluorescence spectra were determined for 3a-e and 4a-e. The X-ray structure analysis of 4a indicates that for the very fast and solvent-independent electron transfer in these systems a specific mechanism involving an interaction of a quinone carbonyl group with the zinc might be considered as an alternative to through-space electron-transfer.
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    Die Dipol-Route zu Furo-/Thieno-Pyrrolen und α-Pyridonen, sowie deren Benzo-Derivaten (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 247-259 
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    ISSN: 0009-2940
    Keywords: Pyrroles, heteroannulated ; α-Pyridones, heteroannulated ; Pentalenes, dihetero- ; Nitrones ; Heterocyclizations, 1,7-dipolar ; Diels-Alder reactions ; Singlet oxygen ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Route to Isoannulated Heteroaroamtic Compounds, 2[1].  -  The Dipole Route to Furo/Thieno Pyrroles and α-Pyridones, and Their Benzo DerivativesA new methodology involving 1,7-dipolar cyclizations of conjugated dipoles followed by a multistep rearrangement affording ring-contracted products has been employed for the synthesis of various examples of the title compounds. Under different thermolysis conditions the annulated alkynyl nitrones 15-19, 45, and 46 are converted into isoannulated pyrroles and α-pyridones, respectively, with yields up to 90% (general reaction A → B + C). The product distribution is strongly influenced by the nature of the terminal substituent R, hence supporting a mechanism with oxo carbenes as central intermediates which undergo either 6-π cyclization to the pyrrole systems or Wolff rearrangement leading to conjugated ketenes, the precursors of the observed α-pyridones (see Scheme 1). Diels-Alder reactions were performed with benzofuropyridone 40a, napthopyridone 62 as well as with the corresponding dihydronaphtho compounds 64a, b. Whereas the tert-butyl derivatives 22b, 23b and 41b are rather unreactive against dienophiles, they are easily transformed into the cyclic imides 31, 32 and 52, respectively, under the influence of oxygen and light suggesting the formation and subsequent [4 + 2] cycloaddition of 1O2 as important steps.
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    Dinuclear Paramagnetic Metallocenes Bridged by Silyl Groups  -  Synthesis and Intramolecular Interactions (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 277-286 
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    ISSN: 0009-2940
    Keywords: Metallocenes, dinuclear, silyl-bridged ; Antiferromagnetism ; Cyclic voltammetry ; Paramagnetic NMR spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dilithium salt of the 3a,4,7a,8-tetrahydro-4,4,8,8-tetra-methyl-4,8-disila-s-indacenediyl dianion (L2-, 2) was allowed to react with the solvated metal halides MX2 (M = Ni, Co, Cr) in the presence of the cyclopentadienyl (Cp) anion to give trans-CpMLMCp (3NiNi, 3CoCo, and 3CrCr) in yields up to 80%. The only cis isomers which could be detected were 4NiNi and 4CoCo. Similarly, the reaction of 2 with [CpVCl(PEt3)]2 gave the trans-vanadium analogue 3VV while the successive reaction of 2 with CrCl3 (THF)3 and PEt3 yielded the bridged half-sandwich (Et3P)Cl2CrLCrCl2(PEt3) (5CrCr). The mixed-metal dinuclear metallocene CpFel—NiCp (3FeNi) was synthesized from CpFel-, Cp- and solvated NiBr2. The molecules were characterized by mass spectrometry, elemental analyses, cyclic voltammetry, 1H—, 13C—, and 29Si—NMR spectroscopy and solid-state magnetic measurements. Cyclic voltammetry showed up to six electron transfers per molecule. A metal-dependent splitting of the half-wave potentials of up to 355 mV indicated rather strong electrostatic interaction between the metallocene units. The NMR results established unpaired spin on the ligands. Its distribution within the bridging ligand was correlated with the molecular orbital splitting and the magnetic interaction. Antiferromagnetic interaction was found for 3NiNi, 3CrCr, and 3VV with J = -11.6, -2.56, and -1.34 cm-1, respectively (H = -J · SA · SB). A temperature-dependent folding of the bridging ligand was deduced from the temperature behavior of the 1H—NMR signal shifts.
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    Untersuchungen am System Phosphirenimin/Iminophosphan  -  Insertionsreaktionen und Isomerisierung (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 313-319 
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    ISSN: 0009-2940
    Keywords: Phosphirene imines ; 1,2-Diphosphete diimines ; Isomerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations of the System Phosphirene Imine/Iminophosphane - Insertion and Isomerization ReactionsTreatment of the iminophosphanes R1P=NR2 1 [R2 = tBu, R1 = Et3C (a); R2 = Aryl, R1 = Et (b), Me (c)] with 1,4-diphenyl-butadiyne (2) leads to the phosphirene imines R1-(R2N=)P̌(Ph)=CCCPh 3a-c and [R1(R2N=)P̌(Ph)=CC]2 4a-c. Further reaction with 1a, c gives the 1,2-diphosphetes R1(R2N=)PP(R1)(=NR2)C(Ph)=CCCPh 5a, b, which isomerize in the case of R1 = Me into the triphosphabicyclo[3.2.0]-hepta-1,6-diene 7. In the reaction of the phosphirene imines R1(ArylN=)P̌(R2)=C(R2) 3 [R1 = Me, R2 = Ph (d); R1 = Et, R2 = COOMe (e)] with the iminophosphanes 1b, d the initially formed diphosphetes 9a, b isomerize to the 1,2-diazaphosphole Cl(Mes*N=)PN(Mes*)P(Me)C(Ph)=C(Ph) 10 or the dioxadiphosphabicyclooctadiene C=C(OMe)OP(=N-Mes*)(Et)C=C(OMe)OP(=NMes*)(Et) 12 depending on the substituents. A reaction of the phosphirene imine 3d with dimethylamino-borane furnishes the vinylphosphane. Ph(H)C=C(Ph)P(Et)N(H)Mes* (14) by ring opening. The compounds 7, 10, 12 have been characterized by X-ray structure analyses.
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    Stereoelektronische Effekte und chirale Erkennung, I. Diastereoselektive Etherbildungen aus Alkylarylcarbinolen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 359-365 
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    ISSN: 0009-2940
    Keywords: Diastereoselectivity ; Effect, kinetic ; Effect, stereoelectronic ; Etherification ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoelectronic Effects and Chiral Recognition, I.  -  Diastereoselective Formation of Ethers from AlkylarylcarbinolsAcid-catalysed etherification of various alkylarylcarbinols 1 leads to a mixture of diastereomeric products 2 and 3. As found in the closely related formation of diastereomeric acetals, the ratio 2/3 is shown to be time-dependent. Preferred formation of the meso-diastereomer 3 under kinetic condition and preferred formation of the racemic diastereomer 2 under thermodynamic conditions is observed. A reaction path based on π-π interactions and stereoelectronic effects is presented to explain experimental results.
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    URL: http://dx.doi.org/10.1002/cber.19941270213
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    Bis(benzo[4,5]thieno)[3,2-c:2′,3′-e][1,2]dithiin, ein Valenzisomer von „Dithioxo-thioindigo“Herrn Professor Wilhelm Pritzkow zum 65. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 401-408 
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    ISSN: 0009-2940
    Keywords: 1,2-Dithiines ; Thioindigo ; Thioketones ; Disulfides, cyclic, molecular structure and reactions ; Valence isomerization, electrocyclic ; Thiophenes, derivatives of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(benzo[4,5]thieno)[3,2-c:2′,3′-e][1,2]dithiin, ein Valenzisomer von „Dithioxo-thioindigo“3-Mercaptobenzo[b]thiophene (1) is transformed with assistance of bases, especially of amines, into the benzo[b]-thieno-annellated 1,2-dithiine 6 and not into the originally claimed “Dithioxo-thioindigo” trans-3. Primarily, the formation of 6 from 1 involves oxidation to the disulfide 4 which may also be used separately. Conceivable rationalizations are discussed. The same compound is accessible (in lower yield)by thionation of thioindigo with the aid of the Lawesson reagent. X-ray elucidation of 6 reveals a non-planar structure of the cyclic disulfide with a dihedral C—S—S—C-angle of 53°. Despite of the absence of any established chromonphoric moiety, 6 is deeply red in the crystal and in solution, as it is representative for the “undisturbed” 1,2-dithiine system. Contrary to the usual behaviour of the non-annellated 1,2-dithiines, 6 displays no spontaneous sulfur extrusion under mild conditions, but only at high temperatures and in the presence of sulfur-binding agents, leading to the benzo[b]thieno-annellated thiophene 22. Moreover, 6 may be reduced to the dithiol 14 (or 13, respectively) and regenerated exclusively from this by oxidation. Further characteristic reactions of 6 are described (e.g. to the sulfoxide 18, to the pyridazine 19, and to the thiphosphoric ester 21).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270217
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    A Molecular-Dynamics Simulation of the Complex Formation between Methyl (R)/(S)-2-Chloropropionate and Heptakis(3-O-acetyl-2,6-di-O-pentyl)-β-cyclodextrin (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 445-445 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270222
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  • 89
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    Tris(perfluororganochalkogenyl)methyl-Verbindungen: Synthesen, Strukturen und Eigenschaften (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 449-455 
    Details
    ISSN: 0009-2940
    Keywords: Trifluoromethylsulfanyl compounds ; Pentafluorophenylsulfanyl compounds ; Trifluoromethylselenanyl compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tris(perfluoroorganochalkogenyl)methyl Compounds: Synthesis, Structures, and PropertiesReaction of (CF3S)2CHC(OC2H5)3 with CF3SCl or CF3SeCl in the presence of NaH in ether provides X(CF3S)2CC(O)OC2H5 (1a, b: X = CF3S, CF3Se). These compounds react with NH3 to form (CF3S)2CHC(O)NH2 (2b) which is also obtained from (CF3S)2CHC(O)OC2H5 and NH3. Dehydration of the amide 2b yields (CF3S)2CHCN (3b), which reacts with NaH and then with CF3SX (X = Cl, SCF3) or with RfCl (Rf = CF3Se, C6F5S) to give Rf (CF3S)2CCN [Rf = CF3S (3c), CF3Se (3d), C6F5S (3e)]. 3c is also obtained from (CF3S)3CBr and AgCN. Hydrolysis of 3c with conc. H2SO4 leads almost quantitatively to (CF3S)3CC(O)NH2 (2c), which on treatment with COCl2 gives only 3c and not the corresponding isocyanate. If phosgene is replaced by oxalyl chloride and treated with 2c in a 1:1 molar ratio, (CF3S)3CC(O)NCO (4a) is formed. The urea derivative (CF3S)3CC(O)NHC(O)NHC(O)C(SCF3)3 (4b) is obtained either by using a 2:1 molar ratio of 2c and [C(O)Cl]2 or from 2c and 4a. Attempts to substitute (CF3S)2CHCO2H - after treatment with NaH in ether - with CF3SCl provides low yields of 2,4-bis[bis(trifluoromethylsulfanyl)methylene]-1,3-dithietane (5). X-ray structure analyses are performed for (CF3S)3CCN (3c) and the 1,3-dithietane 5.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270302
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    Synthese und Koordinationschemie hemilabiler P,N-Hybridliganden mit terminalen 2-Pyridyl-DonorgruppierungenHerrn Professor Dr. O. J. Scherer zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 481-488 
    Details
    ISSN: 0009-2940
    Keywords: 2-Pyridylalkylphosphanes ; Hemilabile ligands ; Nickel complexes ; Palladium complexes ; Platinum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Coordination Chemistry of Hemilabile P,N-Hybride Ligands with Terminal 2-Pyridyl Donor Groups*P,N-hybride ligands 1-7 containing terminal 2-pyridyl donor groups have been obtained by base-catalyzed addition of diphenylvinylphosphane or 2-vinylpyridine to primary or secondary phosphanes [2-Py-(CH2)2-PR′H (R′ = H, Ph), HMeP-(CH2)3-PMeH] or by alkylation of organolithium phosphides, R2P-(CH2)3-PMeLi or 2-Py-(CH2)2-PR′Li (R = Ph, iPr; R′ = H, Ph), with 2-(2-chloroethyl)pyridine or di-tert-butylphosphetanium bromide. Upon reaction with NiBr2 3 H2O or K2MCl4 (M = Pd, Pt) the phosphanes (L) of type 2-Py-(CH2)2-P(R′)-(CH2)m-PR2 (1, 3, 6) form square planar Ni(II), Pd(II), and Pt(II) complexes of composition MX2(L) (10-14). With NiBr2 and K2MX4 the tripod type phosphane 2 forms square pyramidal complexes [MX(2)]X (M = Ni, Pd; X = Cl, Br; 15, 16). An X-ray structural analysis of [NiBr(2)]+Br- (15) reveals a distorted square pyramidal coordination geometry at Ni(II), the 2-Py donor being in apical position with a long Ni—N bond [2.270(15) Å]. The tetradentate ligand 7 forms Ni(II), Pd(II), and Pt(II) complexes MX2(7) which for M = Pd, Pt show dynamic behaviour by exchange of the terminal Py donor groups. With [RhCl(COD)]2 the tridentate ligands L (1 and 3) yield complexes of composition RhCl(L) (20, 21). The structure of 20 has been determinated by X-ray diffraction. The ligand 3, acting in a tridentate manner, is coordinated to Rh(I) in a distorted square-planar arrangement with a normal Rh—N distance [2.145(3) Å].
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270306
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    Study of Calixarenes, V. Friedel-Crafts Reaction of Calixarenes (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 519-523 
    Details
    ISSN: 0009-2940
    Keywords: Calixarenes ; Friedel-Crafts reaction ; selective ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The para-acylation of calix[4]arene (2), calix[6]arene (3), and calix[8]arene (4) by Friedel-Crafts reaction with a wide variety of acyl chlorides leads to 5-7 in moderate to good yields. Friedel-Crafts reaction of 26,28-dimethoxycalix[4]arene (8) gave products 9 selectively disubstituted in the para-positions of phenol rings.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270310
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  • 92
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    Komplexe mit makrocyclischen Liganden, I. Zweikernige Kupfer(II)-Komplexe mit vollständig π-konjugiertem Makrocyclus vom Schiff-Basen-Typ: Synthesen, Strukturen, elektro- und magnetochemische Eigenschaften (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 465-476 
    Details
    ISSN: 0009-2940
    Keywords: Copper(II) complexes, dinuclear ; Schiff bases, macrocyclic ; Redox properties ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes with Macrocyclic Ligands, I. - Dinuclear Copper(II) Complexes with a Totally π-Conjugated Macrocycle of Schiff Base Type: Syntheses, Structures, Electro-, and Magnetochemical PropertiesThe dinuclear copper(II) complexes 6, 7, and 8 of three novel macrocyclic ligands were synthesized by the Schiff base condensation of 2 equiv. of 1,2-phenylenediamine and 2,6-diformylphenol in the presence of 2 equiv. of copper(II) perchlorate and were characterized by X-ray structure analyses, electrochemical investigations (DCV), and variable-temperature magnetic susceptibility measurements. Complex 6 exists in two different solvated crystalline forms. The Copper(II) ions in all three complexes are octahedrally coordinated with long axial distances to solvent molecules or perchlorate ions. The copper ions in 6 (in solvate a) are only five-coordinate and square-pyramidal. The CuIICuII complexes were reduced in successive, quasi-reversible, one-electron steps. The antiferromagnetic exchange interactions were determined. Upon dissolution in acetonitrile complex 8 decomposed to form [Cu(MeCN)4]+ClO-4 and the benzimidazolium percholorate 9 (X-ray structure determination).
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270304
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    {Bis[bis(trimethylsilyl)methyl]stannio(II)}bis(η2-ethen)nickel(0) und verwandte Verbindungen, Teil II (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 489-500 
    Details
    ISSN: 0009-2940
    Keywords: Alkenes ; Nickel complexes ; Stannenes ; Metal-metal bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: {Bis[bis(trimethylsilyl)methyl]stannio(II)}bis(η2-ethene)nickel(0) and Related Compounds, Part IIThe coordinatively unsaturated (16e) (ethene)nickel(0) stannylene complex (C2H4)2Ni=Sn{CH(SiMe3)2}2 (1) reacts with 1,6-heptadiene with preservation of the Ni=Sn bond to yield quantitatively the 1,6-diene derivative (η2,η2-C7H12)Ni=Sn-{CH(SiMe3)2}2 (2). The alkene ligands of both 1 and 2 are readily displaceable. Compounds 1 and 2 react with butadiene at -50°C by a 4-e oxidation of the metal-metal pair Ni(0)/Sn(II) to Ni(II)/Sn(IV) and concomitant reduction of two butadiene molecules to butenediyl moieties to afford stereo-selectively the 16-e complex Ni-cis-{η3(Ni),η1(Sn)-anti-C3H4CH2}2Sn{CH(SiMe3)2}2 (3). Similarly, the reaction of 1 or 2 with isoprene yields regio- and stereoselectively the derivative Ni-cis-{η3(Ni,η1(Sn)-anti-C3(3-Me)H3CH2}2Sn{CH-(SiMe3)2}2 (4). These reactions imply the cleavage of one formal Ni—Sn bond and the formation of two new Sn—C bonds. Upon reaction of 3 with PMe3 the configuration of the allyl system changes and, again fully stereoselectively, the 18-e addition compound (Me3P)Ni-cis-{η3(Ni),η1(Sn)-syn-C3H4-CH2}2Sn{CH(SiMe3)2}2 (5) is formed. When 5 is treated with BPh3, the phosphane ligand is trapped and, kinetically controlled, Ni-cis-{η3(Ni),η1(Sn)-syn-C3H4CH2}2Sn{CH(SiMe3)2}2 (6) is obtained as a stereoisomer of 3. At 40°C 6 slowly rearranges into the thermodynamically stable stereoisomer Ni-trans-{η3(Ni),η1(Sn)-syn-C3H4CH2}2Sn{CH(SiMe3)2}2 (7). Mild protolysis of 3 with pyridine hydrochloride or hydrobromide affords region and stereoselectively (Me3Si)2CH}2(X)SnNi-(η3-1-MeC3H4)(NC5H5) (X = C1, 8a; Br, 8b). In the course of this protonation reaction one butadiene molecule is eliminated, accompanied by a 2-e reduction of the metal-metal pair Ni(II)/Sn(IV) to Ni(II)/Sn(II) and, at the expense of two Sn—C bonds, reformation of a Ni—Sn bond. All compounds are isolated in high yield and fully characterized by 1H-, 13C-, and 31P-NMR spectroscopy.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19941270307
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    Halogen-Kohlenstoff-Schwefel-Verbindungen: Zur Chemie von 1,1,1,4,4,4-Hexafluor-2-buten-2,3-bissulfenylchlorid (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 533-539 
    Details
    ISSN: 0009-2940
    Keywords: Bissulfenyl chlorides ; fluoro substituted ; 1,3-Dithioles ; 1,3,2-Dithiazoles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Halogen-Carbon-Sulfur Compounds: Syntheses with 1,1,1,4,4,4-Hexafluoro-2-butene-2,3-bissulfenyl ChlorideThe bifunctional bissulfenyl chloride 3 is obtained by chlorination of the dithiete 1 or tetrathiocine 2. By excessive chlorination the saturated bissulfenyl chloride 4 is formed. 3 reacts with primary amines to yield the 1,3,2-dithiazoles 5a-e, whereas by reactions with active methylene compounds like ketones or β-dicarbonyls the compounds 7-14 are obtained with HCl elimination. 13 as well as 14 are converted into the carboxylic acid 15 from which the 1,3-dithiole 17 is obtained by decarboxylation. 3 reacts with disulfene to form tetrakis-(trifluoromethyl)tetrathiafulvalene as well as 4,4′,5,5′-tetrakis(trifluoromethyl)-2,2′-spirobi[1,3-dithiole] (18), whose crystal structure has been determined.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941270312
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    Thermal Rearrangements, XXII. The Propargyl-Cope Rearrangement of meso- and d,l-3,4-Dimethyl-1,5-hexadiyne-3,4-diol (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 959-963 
    Details
    ISSN: 0009-2940
    Keywords: Rearrangements, thermal ; Propargyl-Cope reaction ; 1,5-Hexadiyne-3,4-diol ; Cyclobutene ; 3,4-diacetyl ; Fragmentations, retro-ene ; Tandem reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal behavior of meso- and d,1-3,4-dimethyl-1,5-hexadiyne-3,4-diol (meso- and d,1-4) has been studied at 400°C in the gas phase. In a tandem reaction the diols isomerize via the bisallenes 5 first to cis- and trans-3,4-diacetylcyclobutene (cis- and trans-8) which have been detected as intermediates by 13C-NMR spectroscopy as well as catalytic hydrogenation to 1,2-diacetylcyclobutane (9). Subsequently, 8 stabilizes itself by ring opening to (E,Z)- and (E,E)-3,5-octa-dien-2,7-dione (E,Z) and [(E,Z)-6]. As a side reaction retroene cleavage of 4 to 2-butynone (10) and methyl vinyl ketone (12) is observed. By pyrolysis of the pure diastereomers 4 it is shown that the retro-ene process is more pronounced in the d,l than in the meso series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270526
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    Substituierte N,N-Chelat-Liganden - Anwendungen in der Molybdän-katalysierten Olefin-EpoxidationHerrn Prof. Dr. H. Schmidbaur zum 60. Geburtstag gewidmet. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2373-2379 
    Details
    ISSN: 0009-2940
    Keywords: Chelating ligands ; Molybdenum complexes ; Peroxo complexes ; Catalysis ; Olefine epoxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted N,N-Chelate Ligands - Applications in Molybdenum-Catalyzed Epoxidation of Olefins*Oxodiperoxomolybdenum complexes 4 of substituted 2-[3(5)-pyrazolyl]pyridines (2a-g) were synthesized in order to control the solubility of these complexes in organic solvents. Alkyl side chains (butyl, octyl, octadecyl) increase the solubility of the complexes and enable spectroscopic investigations in solution. Due to the symmetry of the ligands the peroxo complexes 4 appear in two isomeric forms, with the terminal oxo ligand in the trans position either to pyridine or to pyrazole. The latter isomer of (C5H4NC3H2N2CH2COOEt)MoO(O2)2 (4f) was characterized by an X-ray structure analysis. The alkyl-substituted peroxo complexes are active catalysts for the epoxidation of olefins with tert-butyl hydroperoxide.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271206
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    A Comparative Study of the Reactivity of Mn(no)2L2H and Mn(CO)3L2H Complexes (L = Phosphorus Donor)Dedicated to Prof. E. Lindner, Universität Tübingen, on the occasion of his 60th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2403-2415 
    Details
    ISSN: 0009-2940
    Keywords: Manganese complexes ; Insertion processes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mn(NO)2L2H complexes [L = PMe3 1a, PEt3 1b, P(OMe)3 1c, P(OEt)3 1d, P(OiPr)3 1e] have been prepared by the reaction of the corresponding Mn(NO)2L2Br compounds with NaBH4 in ethanol. The reactivity of 1a and 1b is compared to that of Mn(CO)3L2H species (L = PMe3 2a, L = PEt3 2b). Compound 1b reacts with weak acids like PhOH, (CF3)2CHOH and CH3COOH to yield Mn(NO)2(PEt3)2X complexes [X = OPh 3a, OCH(CF3)2 3b, OC(O)CH3 3c] and H2. Compound 2b does not undergo reaction with these acids. At room temperature in toluene 1a, b undergo facile CO2 insertion processes, while 2a, b do not show this reactivity even under more rigorous reaction conditions. From 1a, b and CO2 formato complexes Mn(NO)2L2[OC(O)H] (L = PMe3 4a, L = PEt3 4c) are obtained. The reaction of 1b with salicylaldehyde in toluene proceeds with the formation of a [2-(hydroxymethyl)-phenoxy]dinitrosylbis(triethylphosphane) manganese complex 5b, which exchanges the phenoxy ligand in the presence of excess of salicylaldehyde to give (2-formylphenoxy)-dinitrosylbis(triethylphosphane)manganese (6b) and α,2-dihydroxytoluene. p-Hydroxybenzaldehyde, vanilline, and 4-hydroxy-3,5-dimethoxybenzaldehyde and 1b also afford phenoxy derivatives Mn(NO)2(PEt3)2(OAr) [Ar = p-OC6H4-CHO 7a; OC6H3-2-OCH3-4-CHO 7b; OC6H2-2,6-(OCH3)2-4-CHO 7c] and H2. Compounds 2a, b do not react with any of these hydroxybenzaldehydes. Compounds 1a, b have been converted into Mn(NO)2L2 [(Z)-C(COOR′)≡C(R)H] species (L = PMe3, R = H, R′ = Me 8a; L = PEt3, R = H, R′ = Me 8b; L = PMe3 R, R′ = Me 9a; L = PMe3, R = Ph, R′ = Et 10a; L = PMe3, R = COOMe, R′ = Me 11a; L = PEt3, R = COOMe, R′ = Me 11b) in the presence of alkyl propiolates RC≡CCOOMe (R = H, Me, Ph, COOMe; R′ = Me, Et). Similarly, but under more rigorous conditions, insertion of RC≡CCOOMe (R = H, COOMe) into 2a, b occurs and α metalation products Mn(CO)3(PMe3)2[(Z)-C(COOMe) = CHR] (L = PMe3, R = H 12a; L = PEt3, R = H 12b; L = PMe3, R = COOMe 13a; L = PEt3, R = COOMe 13b) are formed. In the case of the methyl propiolate insertion into 2a, 10% of an additional β-metalation compound Mn(CO)3(PMe3)2[(Z)-CH = CH(COOMe)] (12c) have been detected spectroscopically. Compounds 11b and 13a, b have been transformed into manganacyclic complexes MN[C(COOMe)=CH(COOMe)]-(NO)2(PEt3)2 (14b) and MN[C(COOMe)=CH(COOMe)]-(CO)2L2 (L = PMe3 15a; L = PEt3, CO 15b; L = PEt3 15c). Compound 15c has been identified spectroscopically, and 1a, 8a, and 9a have been characterized by X-ray structure determinations.
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    URL: http://dx.doi.org/10.1002/cber.19941271211
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    Synthesis and Complexation of a New 14-Membered N2O2 Macrocycle with vic-Dioxime Moieties (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2483-2488 
    Details
    ISSN: 0009-2940
    Keywords: vic-Dioximes ; N2O2 macrocycles ; Trinuclear complexes ; Pentanuclear complexation ; Tribenzo[b.h.l][1,10,4,7]dioxadiazacyclotetradecine derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new vic-dioxime ligand 2 (LH4) carrying a 14-membered N2O2 macrocycle has been prepared. Mononuclear complex (LH3)2Ni, trinuclear complexes (LH)2Cu3, (LH)2Co3, (LH)2-Pd3, and (LH)2Co3(py)3Cl3, dinuclear complex (LH3)2-(UO2)2(OH)2, and pentanuclear complex [L2Cu5(phen)2]-(NO3)2 have been synthesized from LH4. The electrochemical properties of tri- and pentanuclear complexes were investigated by cyclic voltammetry. For (LH)2Cu3 two reduction waves appeared at 0.215 and -0.870 V. [L2Cu5(phen)2](NO3)2 exhibited four reduction waves at 0.200, -0.025, -0.670, and -1.170 V.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271219
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    Novel, Very Strong, Uncharged Auxiliary Bases; Design and Synthesis of Monomeric and Polymer-Bound Triaminoiminophosphorane Bases of Broadly Varied Steric DemandDedicated to Professor Christoph Rüchardt on the occasion of his 65th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2435-2454 
    Details
    ISSN: 0009-2940
    Keywords: Uncharged auxiliary bases ; Triaminoiminophosphorane bases ; Deprotonation ; Hindered bases ; Polymeric bases ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and properties of a number of very strong iminophosphorane bases up to an extremely high level of steric hindrance are described. They cover a range of ca. 4 pK units in basicity and a range of more than 11 orders of magnitude in their rates of methylation with methyl iodide. Most of the systems are readily prepared in up to molar quantities, conveniently recovered from their salts and are of high chemical and thermal stability. Crystal structures were determined in order to parametrize a force field, which is utilized in molecular modeling studies offering a rationalization of the observed differences in steric hindrance and basicity. Depending on the degree of steric protection of the basic center, these novel bases are proposed as unprecedented, versatile auxiliary bases in E2 eliminations and in reactions involving deprotonation in the presence of more or less strong electrophiles.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19941271215
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    Übergangsmetallsubstituierte Acylphosphane und Phosphaalkene, XXI. Isophosphaalkine als μ3-Liganden in Übergangsmetallkomplexen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1349-1353 
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    ISSN: 0009-2940
    Keywords: Isophosphaalkynes ; Transition metal complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal-Substituted Acylphosphanes and Phosphaalkenes, XXI.  -  Isophosphaalkynes as μ3-Ligands in Transition Metal ComplexesReaction of the μ-isophosphaalkyne complex (η5-C5H5)2 (CO)2(μ-CO)Fe2(μ-CPMes) (Mes = 2,4,6-Me3C6H2) (2a) with [(Z)-Cyclooctene]Cr(CO)5 or Fe2(CO)9 gives rise to the μ3-isophosphaalkyne complexes (η5-C5H5)2(CO)2(μ-CO)Fe2{μ-CP[M(CO)n]Mes} 3a [M(CO)n = Cr(CO)5] and 4a [M(CO)n = Fe(CO)4]. Similarly (η5-C5H5)2(CO)2(μ-CO)Fe2{μ-CP[Cr (CO)5]C6H2(CF3)3-2,4,6} (3d) is obtained. The metal carbonyl fragments are attached to 2 in a η1-fashion by the lone-pair at the phosphorus. In contrast to this the treatment of 2a with (Ph3P)2Pt(η2-C2H4) affords complex 5a in which 2a serves as an η3-3e ligand towards the PtPPh3 moiety. The molecular structures of 3a and 5a are determined by single-crystal X-ray analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270804
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