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  • gene expression  (502)
  • Springer  (502)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • 1995-1999  (307)
  • 1990-1994  (195)
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  • Springer  (502)
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  • 1
    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.
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  • 2
    ISSN: 1432-203X
    Keywords: glyphosate ; gene expression ; gene amplification ; cell culture ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The stability and expression of amplified 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) genes was examined in glyphosate resistant tobacco cells grown in glyphosate-free medium, and in plantlets regenerated from resistant cells. Amplified DNA was maintained in resistant cells grown in the absence of glyphosate for three years. Amplified EPSPS genes were retained in regenerated plantlets at levels comparable to those observed in the resistant cells, and EPSPS mRNA was overexpressed (compared to unselected plantlets). However, glyphosate resistance in cell lines grown in glyphosate-free medium declined 7-fold, and in regenerated plantlets approximately 20-fold, compared to resistant cells maintained under glyphosate selection. In plantlets, reduced resistance correlated with lower levels of EPSPS mRNA. Plantlets regenerated from resistant cells exhibited morphological variation, and had an approximate doubling of their nuclear genome size.
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  • 3
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    Cellular and molecular life sciences 47 (1991), S. 866-877 
    ISSN: 1420-9071
    Keywords: Transgenic mice ; microinjection ; recombinant DNA ; gene expression ; transcription factors ; chromatin ; homologous recombination ; episomal maintenance ; embryonic stem cells ; germ line ; position-effect ; mosaicism ; globin genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This chapter is an attempt to summarize some commonly accepted and some more subjective opinions about the regulation of transgene expression in laboratory animals. After a short historical introduction, I present some general notions regarding gene structure/function. The spotlight shifts then to the description of the most popular techniques for gene transfer, including the targeted gene replacement. The different approaches are briefly discussed in terms of intrinsic advantages and limitations regarding gene expression patterns. Furthermore, the role of enhancers, promoters and othercis-acting elements such as silencers and dominant control regions as well as their involvement in the chromatin on-off state are discussed on the basis of a specific example studied in our laboratory. The review concludes by presenting recent results and the new perspectives opening in the field of ‘surrogate’ (also called ‘reversed’) genetics. Some problems which remain to be solved both at the technical as well as at the social-ethical level are also briefly presented.
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  • 4
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    Cellular and molecular life sciences 50 (1994), S. 958-962 
    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.
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  • 5
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    Cellular and molecular life sciences 49 (1993), S. 447-455 
    ISSN: 1420-9071
    Keywords: Proteoglycan ; chondroitin sulfate ; decorin ; gene expression ; tumor stroma ; DNA methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Tumor stroma is a specialized form of tissue that is associated with epithelial neoplasms. Recent evidence indicates that significant changes in proteoglycan content occur in the tumor stroma and that these alterations could support tumor progression and invasion as well as tumor growth. Our main hypothesis is that the generation of tumor stroma is under direct control of the neoplastic cells and that, via a feedback loop, altered proteoglycan gene expression would influence the behavior of tumor cells. In this review, we will focus primarily on the work from our laboratory related to the altered expression of chondroitin sulfate proteoglycan and its role in tumor development and progression. The connective tissue stroma of human colon cancer is enriched in chondroitin sulfate and the stromal cell elements, primarily colon fibroblasts and smooth muscle cells, are responsible for this biosynthetic increase. These changes can be reproduced in vitro by using either tumor metabolites or co-cultures of human colon carcinoma cells and colon mesenchymal cells. The levels of decorin, a leucine-rich proteoglycan involved in the regulation of matrix assembly and cell proliferation, are markedly elevated in the stroma of colon carcinoma. These changes correlate with a marked increase in decorin mRNA levels and a concurrent hypomethylation of decorin gene, a DNA alteration associated with enhanced gene expression. Elucidation of decorin gene structure has revealed an unexpected degree of complexity in the 5′ untranslated region of the gene with two leader exons that are alternatively spliced to the second coding exon. Furthermore, a transforming growth factor beta (TGF-β)-negative element is present in the promoter region of decorin gene. This regulatory domain is likely to be implicated in the silencing of decorin gene by TGF-β and may contribute to the regulation of this matrix gene in the tumor stroma.
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  • 6
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    Cellular and molecular life sciences 47 (1991), S. 905-912 
    ISSN: 1420-9071
    Keywords: Gene transfer ; gene modification ; gene expression ; livestock ; transgenic animal ; pharmaceutical proteins ; milk composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract There is every reason to expect that it will be possible within the next few years to begin to use farm animals to produce large quantities of some of the human proteins that are needed for the treatment of disease. Revolutionary new opportunities for the production of novel proteins in milk have been created by the development of methods for gene transfer. Exploitation of these opportunities depends upon selection and cloning of milk protein genes and identification of the sequences that govern tissue specific hormonally induced expression in the mammary gland. Studies with three genes, ovine β-lactoglobulin, rat β-casein and whey acidic protein of rat and mouse, suggest that they may all meet this requirement. Fragments of the ovine β-lactoglobulin, murine whey acidic protein and rabbit β-casein genes have directed production of novel proteins in the milk of transgenic mice, sheep, rabbits and pigs. The proteins were biologically active and usually co-migrated with authentic proteins. In early experiments, protein concentration was low, but our recent observations suggest that fusion genes containing genomic clones direct production of concentrations of protein that are suitable for commercial exploitation. In the longer term, two approaches may offer the potential of more reliable expression. Control elements capable of directing expression that is independent of site of insertion of the gene, but dependent on the number of copies of the gene, have been identified for a small number of genes. The availability of such elements for the milk protein genes would increase the reliability of gene expression considerably. Alternatively, targeted mutation of genes may allow the insertion of coding sequences within an existing gene so avoiding position effects.
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  • 7
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    Cellular and molecular life sciences 49 (1993), S. 133-137 
    ISSN: 1420-9071
    Keywords: Fetal hemoglobin ; sickle cell anemia ; β thalassemia ; butyrate ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The inherited β-hemoglobinopathies (sickle cell disease and β thalassemia) are the result of a mutation in the adult (β) globin gene. The fetal globin chain, encoded by the γ globin genes, can substitute for the mutated or defective β globin chain, but expression of the γ globin gene is developmentally inactivated prior to birth. Reinducing expression of the normal fetal globin genes is a preferred method of ameliorating sickle cell disease and the β thalassemias. Stimulation of as little as 4–8% fetal globin synthesis in the bone marrow can produce 〉20% fetal hemoglobin in the peripheral circulation, due to enhanced survival of red blood cells containing both sickle and fetal hemoglobin, compared to those containing sickle hemoglobin alone. Butyric acid and butyrate derivatives are generally safe compounds which induce fetal hemoglobin production by stimulating the promoter of the fetal globin genes. An initial trial with the parent compound, delivered as Arginine Butyrate, has demonstrated rapid stimulation of fetal globin expression to levels that have been shown to ameliorate these conditions. Phase 1 trials of an oral butyrate derivative with a long plasma half-life have just begun. These agents now provide a specific new apporach for ameliorating these classic molecular disorders and merit further investigation in larger patient populations.
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  • 8
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    Cellular and molecular life sciences 52 (1996), S. 942-949 
    ISSN: 1420-9071
    Keywords: Apoptosis ; transglutaminase ; signalling ; gene expression ; promoter elements ; retinoic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Clarification of the molecular details of forms of natural cell death, including apoptosis, has become one of the most challenging issues of contemporary biomedical sciences. One of the effector elements of various cell death pathways is the covalent cross-linking of cellular proteins by transglutaminases. This review will discuss the accumulating data related to the induction and regulation of these enzymes, particularly of tissue type transglutaminase, in the molecular program of cell death. A wide range of signalling pathways can lead to the parallel induction of apoptosis and transglutaminase, providing a handle for better understanding the exact molecular interactions responsible for the mechanism of regulated cell death.
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  • 9
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    Cellular and molecular life sciences 51 (1995), S. 1116-1123 
    ISSN: 1420-9071
    Keywords: Antisense RNA ; gene expression ; insertional mutagenesis ; physical mapping ; reporter genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Over the past ten years, powerful molecular genetic techniques have been developed to analyze gene function inDictyostelium. DNA-mediated transformation using a variety of selections and vectors has allowed the introduction of wild-type or modified genes that are under various forms of transcriptional control. Homologous recombination is efficient and can be used to modify the genome in precise ways. In addition, it is now possible to clone genes based on their mutant phenotype alone, either by insertional mutagenesis, or by screening antisense expression cDNA libraries. Finally, a nearly complete physical map of the genome is available and so genes are easily mapped by physical techniques. We discuss many of these advances within the context of major research problems presently under study.
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  • 10
    ISSN: 1420-9071
    Keywords: Aldehyde dehydrogenase ; developmental changes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous reports suggested that the major cytosolic aldehyde dehydrogenase (ALDH1) was present in fetal and infant livers, but the major mitochondrial isozyme (ALDH2) was absent or severely diminished. Re-examination by means of starch gel electrophoresis followed by enzyme activity staining, and by means of dot blot immuno-hybridization of liver samples with known genotypes of theALDH 2 locus, indicated that bothALDH 1 andALDH 2 genes are expressed in fetal and infant livers. In addition, ALDH4 isozyme was also observed. The results imply that a fetus with the ‘usual’ homozygousALDH 2 1 /ALDH 2 1 genotype, but not one with the atypicalALDH 2 1 /ALDH 2 2 orALDH 2 2 /ALDH 2 2 , is capable of detoxifying acetaldehyde transferred from the mother.
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  • 11
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    Cellular and molecular life sciences 47 (1991), S. 22-31 
    ISSN: 1420-9071
    Keywords: Atherosclerosis ; cellular differentiation ; gene expression ; foam cells ; lipoproteins ; phorbol esters ; transcription factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary THP-1 is a human monocytic leukemia cell line. After treatment with phorbol esters, THP-1 cells differentiate into macrophage-like cells which mimic native monocyte-derived macrophages in several respects. Compared to other human myeloid cell lines, such as HL-60, U937, KG-1, or HEL cell lines, differentiated THP-1 cells behave more like native monocyte-derived macrophages. Because of these characteristics, the THP-1 cell line provides a valuable model for studying the mechanisms involved in macrophage differentiation, and for exploring the regulation of macrophage-specific genes as they relate to physiological functions displayed by these cells.
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  • 12
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    Cellular and molecular life sciences 52 (1996), S. 888-891 
    ISSN: 1420-9071
    Keywords: Ageing ; rat ; brain ; gene expression ; differential display
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have used the polymerase chain reaction (PCR)-based technique of differential display to analyse changes in gene expression during ageing of the rat brain. In this approach we have compared three young adult (6 months) with three old adult (20 months) animals. RNA preparations from the homogenised brains were subjected to reverse transcriptase (RT)-PCR using 36 different combinations of primer pairs. Any PCR product which was consistently found to be more prominent in the three young brains compared to the three old brains, and vice versa, was scored as potentially representing a gene which was differentially expressed during the ageing of this tissue. Out of a possible 2000+PCR products we identified 44 that might represent genes that exhibit differential expression during ageing of the rat brain. An initial screen of these fragments, by Southern-blotting the PCR products and hybridising them with cDNA probes derived from either young or old brain RNA preparations, indicated that 40% of them represented genes that were differentially expressed. This approach is likely to prove invaluable for identifying cohorts of genes that show differential expression during the ageing process.
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  • 13
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    Cellular and molecular life sciences 47 (1991), S. 321-331 
    ISSN: 1420-9071
    Keywords: Symbiosis ; ectomycorrhiza ; ectomycorrhiza development ; gene expression ; ectomycorrhizins ; protein patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ectomycorrhiza, a specialized root organ, is the result of a complex interaction leading to a finely-tuned symbiosis between a plant and a compatible ectomycorrhizal fungus. Ultrastructural observations combined with cytochemical and biochemical studies reveal that structural and metabolic changes in the symbiont cells lead to the final phenotype of the active ectomycorrhiza. In the present review these changes are interpreted as changes in gene expression and discussed within the context of ectomycorrhiza development. Recent genetic data indicate that the continued vegetative growth of the ectomycorrhizal hyphae and the root tissues, and their ability to switch to symbiotic organ formation, is basically controlled by developmentally critical genes. The activity of these ‘symbiotic genes’ during the differentiation of ectomycorrhizas is associated with extensive changes in the concentration of particular polypeptides and protein biosynthesis. The present state of knowledge about the developmental biology of ectomycorrhizas allows only speculation about the events during their development.
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  • 14
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    Cellular and molecular life sciences 51 (1995), S. 606-611 
    ISSN: 1420-9071
    Keywords: Metallothionein ; isometallothioneins ; gene expression ; rabbit kidney cell-line ; cadmium adaptation ; zinc adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We explored the molecular genetics underlying the massive induction of isoMTs by Zn2+ or Cd2+ in metal tolerant rabbit kidney (RK-13) sub-line cells, using band shift assays and Southern blotting analysis. In sub-line cells accommodated to intermediate metal concentrations (100 μM Zn2+; 1–20 μM Cd2+) evidence suggested that the increase in the capacity for isoMT synthesis is brought about by an increased binding activity of the nuclear transcription factors MTF-1 and Sp1. Using quantitative band shift analysis with a mouse MRE-d oligonucleotide probe, the binding of both transcription factors was found to be enhanced two to three times over the binding activity measured in the unexposed parental RK-13 cells. Their increase in binding activity is probably the cause of the overexpression of MT genes and the development of metal tolerance in these cells. In cells tolerant to the highest concentrations of metal the analysis of Southern blot signals revealed MT gene amplification to be the most probable cause of the increased MT production. Thus, in cells of sub-lines growing in the presence of 350 μM Zn2+, two of the isoMT genes were coordinately triplicated and in cells tolerant to 150 μM Cd2+ one isoMT gene was amplified two-fold.
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  • 15
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    Plant cell reports 10 (1991), S. 308-314 
    ISSN: 1432-203X
    Keywords: Agrobacterium tumefaciens ; Brassica juncea ; genetic transformation ; gene expression ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An efficient system for gene transfer into plants of Brassica juncea var. India Mustard, mediated by Agrobacterium tumefaciens. was developed through the manipulation of the culture medium and the use of the appropriate Agrobacterium strain. High frequency shoot regeneration (90–100%) was obtained from hypocotyl explants grown on medium containing 0.9% agarose, 3.3 mg/L AgNO3 and 0.5–2 mg/L BA in combination with 0.01–0.05 mg/L 2,4-D or 0.1–1 mg/L NAA. Of all the Agrobacterium strains tested, A. tumefaciens A208-SE, carrying the disarmed Ti plasmid and a binary vector pROA93, was the most effective for B. juncea transformation. pROA93 carries the coding sequences of the NPTII and the GUS genes, both driven by a common CaMV 35S promoter in two divergent directions. Inoculated explants grown on the selection medium in the presence of 0.5 mg/L BA and 0.1 mg/L NAA gave rise to transgenic shoots at the highest frequency (9%). All Ro transgenic plants were phenotypically normal, but variation in expression patterns of the GUS gene occurred among the transgenic plants in an organ- and tissue-specific manner. Both the NPTII and the GUS genes were transmitted to the R1 seed progeny and showed co-segregation.
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  • 16
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    Plant molecular biology reporter 17 (1999), S. 371-383 
    ISSN: 1572-9818
    Keywords: epidermal peel ; extraction ; gene expression ; stomata ; tree tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stomatal guard cells are critical for maintenance of plant homeostasis and represent an interesting cell type for studies of leaf cell differentiation and patterning. Here we describe techniques for the isolation of guard cell RNA and protein from blended epidermal peels of Nicotiana glauca. The RNA isolation procedure is a modification of the hot borate method, which is particularly well-suited for recalcitrant tissues. Protein was extracted by disrupting guard cell-enriched epidermis with a French® press. This system offers the following advantages: relatively high yield, low or no contamination by other cell types, fresh tissue as a source of RNA and protein rather than protoplasts, and a plant species that is readily transformable. These techniques will allow for cloning and analysis of genes expressed in guard cells, application of traditional biochemical techniques to guard cell proteins, as well as characterization of genetic manipulation of guard cell function in transgenic plants.
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  • 17
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    Antonie van Leeuwenhoek 59 (1991), S. 65-76 
    ISSN: 1572-9699
    Keywords: anaerobic respiration ; FNR protein ; oxygen regulation ; gene expression ; E. coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular oxygen is an important regulatory signal in facultative anaerobic bacteria and controles the expression of a great variety of genes positively or negatively. The expression of anaerobic respiration and of related functions of E. coli is controlled by the positive gene regulator FNR, which activates transcription in the absence of O2. The regulated genes carry a FNR consensus sequence upstream of the promoter. Under the same conditions FNR represses some of the genes of aerobic respiration. The binding to the DNA occurs by an α-helix-turn-α-helix DNA-binding domain. FNR contains 5 cysteine residues, four of which are arranged in a cluster close to the N-terminal end. For the function of FNR as a O2-dependent regulator three of the cysteine residues in the cluster and the residue outside the cluster are essential. FNR binds iron as a cofactor which most likely is involved in the O2-sensing by the protein. The experiments indicate that the cysteine residues are responsible for the binding of the iron. From the protein in vivo two functional states can be differentiated, an aerobic or metal-depleted form and an anaerobic form. Only the anaerobic form acts as a gene activator or repressor. Sensing of O2 or of positive redox potentials by the iron ion is thought to cause the conversion of the two functional states. The FNR protein in addition contains a potential nucleotide binding domain. The significance and function of this site is not clear.
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  • 18
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    BioMetals 11 (1998), S. 345-358 
    ISSN: 1572-8773
    Keywords: calcium ; CREB ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Through the evolution of multicellular organisms, calcium has emerged as the preferred ion for intracel-lular signalling. It now occupies a pivotal role in many cell types and nowhere is it more important than in neurons, where it mediates both the relaying and long-term storage of information. The latter is a process that enables learning and memory to be formed and requires the activation of gene expression by calcium signals. Evidence from a number of diverse organisms shows that transcription mediated by the transcrip-tion factor CREB is critical for learning and memory. Here we review the features of CREB activation by calcium signals in mammalian cells. In contrast to other transcription factors, its regulation is dependent on an elevation of nuclear calcium concentration, potentially placing this spatially distinct pool of calcium as an important mediator of information storage.© Kluwer Academic Publishers
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  • 19
    ISSN: 1573-904X
    Keywords: gene expression ; hPepTl ; Caco-2 cells ; adenovirus ; drug screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Our goals are to establish an in vitro screening system and to evaluate a new approach in improving oral absorption of peptides and peptide-like drugs by overexpression of the human intestinal oligo-peptide transporter (hPepTl). This study characterizes the expression of hPepTl in human intestinal Caco-2 cells, rat intestinal epithelial cells (IEC-18), and human cervix epithelial cells (Hela) after adenoviral transduction. Methods. A recombinant replication-deficient adenovirus carrying the hPepTl gene was made and used as a vector for the expression of hPepTl. The increase in the uptake permeability of cephalexin and Gly-Sar was determined. The effects of time, dose, apical pH, and substrate specificity were evaluated. Results. A significant increase in the uptake permeability of Gly-Sar and cephalexin was found in all three cell lines after viral transduction. The increase of Gly-Sar permeability in Hela, IEC-18, and Caco-2 cells was 85-, 46-, and 15-fold respectively. Immunoblotting using an antibody against hPepTl detected high levels of a 85-98-kDa protein in all three infected cell lines. Substrate permeability was dependent on time of infection, inward pH gradients, and multiplicity of infection (MOI). Decreased infectivity and lower hPepTl expression were observed in differentiated Caco-2 cells. The uptake was inhibited by dipeptides and β-lactam antibiotics but not amino acids. Conclusions. Adenoviral infected Hela cells displayed a pronounced level of hPepTl expression with a low background and high specificity to dipeptides. These features make this system a useful tool for screening of potential substrates. The success of overexpression of hPepTl in Caco-2 and IEC-18 cells may lead to a novel approach in improving oral absorption of peptides and peptidomimetic drugs.
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  • 20
    ISSN: 1573-904X
    Keywords: adriamycin ; doxorubicin ; HPMA copolymer ; apoptosis, multidrug resistance ; gene expression ; signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study peculiarities and the mechanism of the anticancer effect of free and HPMA copolymer-bound ADR in sensitive and resistant human ovarian carcinoma cells. Methods. Sensitive A2780 and ADR resistant A2780/AD cells were exposed to different doses of drugs during 12, 24, 36, 48, 60, and 72 hours. Cell viability, drug accumulation, apoptosis, cellular metabolism, lipid peroxidation, DNA content and gene expression were studied. Results. HPMA copolymer-bound ADR (P(GFLG)-ADR) possessed a comparable cytotoxicity to free ADR when comparison was based on intracellular concentrations. While free ADR up-regulated genes encoding ATP driven efflux pumps (MDR1, MRP), P(GFLG)-ADR overcame existing pumps and down regulated the MRP gene. Free ADR also activated cell metabolism and expression of genes responsible for detoxification and DNA repair. P(GFLG)-ADR down-regulated HSP-70, GSr-π, BUDP, Topo-IIα, β, and TK-1 genes. Apoptosis, lipid peroxidation and DNA damage were significantly higher after exposure to P(GFLG)-ADR, as reflected by simultaneous activation of p53, c-fos in A2780 cells) or c-jun (A2780/AD) signaling pathways and inhibition of the bcl-2 gene. Differences between free ADR and P(GFLG)-ADR increased with the time of incubation and drug concentration. Conclusions. P(GFLG)-ADR overcame drug efflux pumps, more significantly induced apoptosis and lipid peroxidation, inhibited DNA repair, replication, and biosynthesis when compared to free ADR.
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  • 21
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    Biologia plantarum 42 (1999), S. 241-248 
    ISSN: 1573-8264
    Keywords: Arachis hypogaea ; gene expression ; lipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ability of peanut (Arachis hypogaea L.) to grow at high concentrations of NaCl may be due to the alteration in gene expression. SDS-PAGE analysis has revealed that plants grown under NaCl showed induction (127 and 52 kDa) or repression (260 and 38 kDa) in the synthesis of few polypeptides. In addition, nine different esterase isoenzymes were detected in embryos of seeds germinated in 105 mM NaCl, whereas only five of them were detected in the embryos of untreated seeds. On the other hand, in the cotyledons, the esterase pattern was not affected by NaCl concentration. The esterase patterns of both stems and leaves were less influenced by NaCl in comparison to those of roots. The lipid contents, and fresh and dry masses were increased up to 45 mM NaCl and decreased at higher concentrations.
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  • 22
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    Biologia plantarum 42 (1999), S. 209-216 
    ISSN: 1573-8264
    Keywords: algae transformation ; bacterial genes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A transgenic expression system of Chlorella kessleri using the gene for β-glucuronidase (GUS) was developed. Cells of this unicellular green alga were bombarded with the plasmid pBI 121, which bears β-glucuronidase under the control of CaMV 35S promoter and the kanamycin resistant gene. Maximum GUS activity was obtained after 48 h of bombardment using a helium pressure of 900 kPa; GUS activity was then assayed for many generations. The stable transformants were able to grow on kanamycin containing medium after repeated passages between selective and nonselective medium and exhibited GUS activity comparable to that of control cells. Stable transformed cells were confirmed by polymerase chain reaction (PCR) and Southern hybridization of GUS probe with the genomic DNA of C. kessleri.
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  • 23
    ISSN: 1573-8264
    Keywords: auxin ; cDNA fragments ; gene expression ; Malus x domestica Borkh ; PCR ; Prunus dulcis Mill ; rhizogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Differential display of mRNA has been recently developed as a tool to detect and characterize changes in gene expression. We applied this technique to fruit trees plantlets induced to root in vitro, in order to isolate and study genes involved in root induction. A reproducible pattern of polymerase chain reaction (PCR) products was obtained, both in almond and apple, in vertical polyacrylamide gels stained with ethidium bromide. Differences in PCR fingerprinting were detected in mRNAs of basal part of either auxin induced or non induced microcuttings. Thus, we suggest that this technique can be used in woody species to detect changes among mRNA populations during root induction.
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  • 24
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    European journal of plant pathology 105 (1999), S. 519-533 
    ISSN: 1573-8469
    Keywords: genome ; gene expression ; mollicute ; recombination ; transposition ; virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Spiroplasmas are members of the Class Mollicutes, wall-less prokaryotes having a high adenosine–thymidine content in their small genomes. Spiroplasma citri is a plant pathogen that inhabits phloem. Like other phytopathogenic spiroplasmas and the related phytoplasmas, it is transmitted from plant to plant by phloem-feeding leafhoppers that serve as alternate hosts for the spiroplasma as well as vectors. Genetic information in spiroplasmas is carried on a circular chromosome, on plasmids and/or in virus genomes. A picture emerging from recent research on the S. citri genome is one of frequent and often extensive variation, resulting from a number of different mechanisms. Expansion and contraction events must continually be occurring in about equal proportions so that the net genome size varies within defined boundaries. Particularly impressive are large changes in genome size that can occur in only a few generations. As with most organisms, genetic variation in S. citri results from variation in extrachromosomal DNA content, changes due to DNA replication and repair processes and changes due to recombination. The implied flux of genetic information into and out of the S. citri genome should be beneficial to the bacterium, allowing it, with its small genome size, to adapt to new environments.
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  • 25
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    European journal of plant pathology 98 (1992), S. 175-181 
    ISSN: 1573-8469
    Keywords: Nematodes ; Globodera ; plant pathogen ; infection ; monoclonal antibodies ; PCR ; cDNA libraries ; gene expression ; modified plant cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Current control of nematodes is inadequate and this justifies work towards the design of novel bases for plant defence. Our approach for cyst nematodes began by improving understanding of critical events in the establishment of these biotrophic pathogens. The first step involved development of an experimental system for achieving synchronous infection and establishment of cyst-nematodes in roots. Monoclonal antibodies have been raised against these nematodes, their specificity defined and those of particular interest used to define events in the establishment of the animals within plants. A similar approach has been explored for host responses using antibodies raised to plant tissue containing feeding sites. Changes in translatable mRNA populations at the feeding site have been described.
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  • 26
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    Bulletin of experimental biology and medicine 117 (1994), S. 122-124 
    ISSN: 1573-8221
    Keywords: gene expression ; c-myc ; Ca-ATPase
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    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.
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  • 27
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    Bulletin of experimental biology and medicine 124 (1997), S. 1116-1117 
    ISSN: 1573-8221
    Keywords: plasmid ; chromosomal genes ; transfer inhibition system ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Specificity ofE. coli K-12 chromosomal Thr-Leu-segment (genetic locus tis) regulating the expression of systems inhibiting Flac plasmid transfer is revealed. The findings point to a complex (polygenous) structure of this locus.
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  • 28
    ISSN: 1573-5168
    Keywords: fish ; gene expression ; GH ; GtH ; gonad ; growth factors ; RT-PCR ; salmonid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this study, Northern blot analysis of RNA from trout testis revealed a single transcript of insulin-like growth factor II (IGF-II) around 4.7 kb. The cellular distribution of IGF-II mRNA was studied and quantified in different testicular cells enriched populations by RT-PCR. IGF-II mRNA appears to be expressed in all cellular types tested: spermatogonia A and B, primary spermatocytes, spermatids and secondary spermatocytes and Sertoli cells. A significantly higher expression of IGF-II was found in premeiotic germ cells. The levels of IGF-II mRNA appear to be higher than those of IGF-I in immature trout testis, as judged from the semi-quantitative RT-PCR results. These data suggest that in addition to IGF-I, IGF-II may play a role in testicular physiology in fish. The hormonal regulation of IGF-I and IGF-II gene expression was investigated both in vitro and in vivo using RT-PCR approach. Gonadotropin (GtH) added to testicular explants increased IGF-II mRNA levels but had no effect on IGF-I. No statistically significant effect was observed with androgens. In vivo, GH and pituitary extracts resulted in an 8 fold and 2-3 fold increase in both IGF-I and IGF-II mRNA levels, respectively. Taken together, our study suggests that IGF-I and IGF-II may act as local mediators of GH and GtHs in fish testis. Moreover, our results imply that in fish testicular cells, IGFs are potential paracrine/autocrine regulators inside the spermatogenic compartment and can act directly on germ cells to stimulate their proliferation.
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  • 29
    ISSN: 1573-5168
    Keywords: precursor proteins of egg envelope ; choriogenin H ; choriogenin L ; estrogen receptor ; estrogen ; vitellogenin ; oogenesis ; choriogenesis ; gene expression ; transcriptional factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The time course and pattern of expression of the genes for choriogenin H and choriogenin L in the liver of the E2-treated male fish was investigated according to the methods of dot blotting analysis and in situ hybridization. Four hours after the beginning of estrogen treatment (final concentration in rearing water: 100 ng ml-1), expression of the choriogenins genes was induced in every parenchymal cell in the liver and the amounts of the gene transcripts were generally increased. As a primary step for analysis of the mechanism of the estrogen action, the amount of estrogen receptor and expression of its gene were examined in the liver of estrogen-treated male fish.
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  • 30
    ISSN: 1573-8221
    Keywords: plasmid ; transception ; transcipient ; segregation ; gene expression
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    Topics: Biology , Medicine
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  • 31
    ISSN: 1573-4919
    Keywords: mouse ; protein tyrosine phosphatase ; cDNA cloning ; nucleotide sequence ; gene expression
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    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The PTP-2 cDNA encoding an intracellular protein tyrosine phosphatase (PTPase-2) was isolated and sequenced from mouse testis and T-cell cDNA libraries. This PTP-2 cDNA was found to be homologous to human PTP-TC and rat PTP-S, and contained 1,551 nucleotides, including 1,146 nucleotides encoding 382 amino acids as well as 5′ (61 nucleotides) and 3′ (344 nucleotides) non-coding regions. Northern blot analysis indicated that PTP-2 mRNA of 1.9 Kb was most abundant in testis and kidney, although it was also present in spleen, muscle, liver, heart and brain.
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  • 32
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    Molecular and cellular biochemistry 133-134 (1994), S. 235-243 
    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.
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  • 33
    ISSN: 1573-4919
    Keywords: poly(ADP-ribosyl) transferase (human) ; autoregulation ; gene expression ; promoter structure ; cruciform structure
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    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.
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  • 34
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    Molecular and cellular biochemistry 155 (1996), S. 153-162 
    ISSN: 1573-4919
    Keywords: apolipoprotein B and E ; lipid ; gene expression ; rat ; mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The aim of the present investigation was to study the regulation of apolipoprotein E by two dietary nutrients, saturated fat and cholesterol, known to raise plasma cholesterol levels. ApoE is a protein component of several classes of lipoproteins including VLDL and HDL, and dietary lipids may regulate VLDL and apoE-containing HDL particles through their effects on apoE gene. Male rats and mice were fed the following 4 diets: control diet (C); high cholesterol diet with 0.5% cholesterol (HC); high fat diet with 20% hydrogenated coconut oil (HF); and high fat plus high cholesterol diet with 0.5% cholesterol and 20% fat (HF/C). Plasma cholesterol levels remained unchanged on HC diet, but in mice VLDL-cholesterol increased by 31%. HF diet increased VLDL and LDL by 15–17% in rats, and 21% in mice. A combination of fat and cholesterol diet showed pronounced effects on plasma lipoprotein concentrations, raising apoB-containing particles by 21% and 44% in mice and rats, respectively. Plasma apoE levels increased significantly on all diets. The mechanism of regulation of increased plasma apoB and apoE levels was examined. Quantification of hepatic apoB mRNA showed a lack of correlation between plasma apoB and hepatic apoB mRNA levels, suggesting that posttranscriptional regulation increased plasma apoB-containing lipoproteins in animals fed saturated fat diets. Hepatic apoE mRNA levels increased significantly in animals fed cholesterol-rich diets. However, despite increased plasma apoE levels on diet containing only saturated fat, hepatic apoE mRNA did not change. Synthesis of apoE on the liver polysomes increased selectively on cholesterol-rich diets. These results suggest that cholesterol-rich diets altered apoE, in part, by transcriptional mechanism, and saturated fat-rich diets increased plasma apoE levels by posttranscriptional mechanism, possibly decreased receptor-mediated uptake of apoE-containing particles. The regulation of LDL receptor was also studied since plasma apoB and E levels may be altered by LDL receptor-mediated uptake by the hepatocytes. As expected, high cholesterol diet decreased LDL receptor mRNA by 30–40%. However, the LDL receptor protein on liver membranes did not change on any of the test diets in both animal species. Hepatic cholesterol content increased several fold selectively on high cholesterol diets. These findings suggest that: 1) both transcriptional and posttranscriptional mechanisms are important in regulating plasma apoB and E containing lipoproteins; 2) dietary cholesterol regulates apoE gene by a transcriptional mechanism anddietary saturated fat by posttranscriptional mechanism; and 3) changes in the hepatic apoE and LDL receptor mRNA are associated with the changes in intracellular cholesterol concentrations.
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  • 35
    ISSN: 1573-4919
    Keywords: fatty acid transport protein ; gene expression ; subtractive hybridization ; oxidative stress ; ischemia/reperfusion ; ischemic preconditioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In this study, ischemia and oxidative stress-inducible gene expression in heart was examined by subtractive hybridization technique. Total RNA was isolated from ventricular muscle fragments of normal and oxidative stress-induced hearts. Poly (A)+ RNA was purified followed by the construction of a plasmid cDNA library. This was followed by the subtractive screening of oxidative stress-induced cDNA library. The positive colonies were amplified and the plasmid isolated. An aliquot was subjected to restriction cutting with Bam H1 and EcoRl; the fragments corresponding to cDNA insert were separated by electrophoresis, radiolabeled by random-primed DNA synthesis, and used as probes in standard Northern blotting experiments. An aliquot containing the plasmid from the confirmed positives was then subjected to bidirectional partial DNA sequencing (using M13 and T7/T3α primers) by the chain-extension/chain termination method. These sequences were subjected to a computerized search for homologies against all sequences in the updated worldwide Gen Bank and EMBL sequence databases followed by restriction mapping and reading frame identification. Out of 24 putative positive colonies screened, one clone was matched with 〉 97% homology with FAT gene that has been implicated in binding or transport of long chain fatty acids. cDNA probe synthesized from this clone identified two major transcripts of 4.8 and 2.9 kb. Additional experiments were then performed where isolated perfused rat hearts were subjected to the following treatments: (1) 5 min ischemia; (2) 10 min ischemia; (3) 20 min ischemia; (4) 5 min ischemia followed by 10 min reperfusion (ischemic preconditioning); and (5) 5 min ischemia followed by 10 min reperfusion, repeated four times (4 × preconditioning). RNAs were extracted from these hearts and hybridized with the FAT cDNA probe. The results indicated that FAT gene was induced by oxidative stress, ischemic preconditioning, but not by ischemia. (Mol Cell Biochem 160/161: 241–247, 1996)
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  • 36
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    Molecular and cellular biochemistry 163-164 (1996), S. 231-237 
    ISSN: 1573-4919
    Keywords: extracellular matrix ; angiotensin II ; fibrillar collagen ; cardiac fibrosis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Recent studies suggest that angiotensin II (angiotensin) may be involved in the regulation of metabolism of the cardiac extracellular matrix (ECM). Two major components of ECM are collagen types I and III which play an important role in maintaining the structure and function of the heart. Although the cellular metabolism of collagen is very complex (especially at the posttranslational level), we chose to address events that occur relatively early in the synthesis of cardiac collagen molecules. To gain an understanding of the role of angiotensin in the regulation of cardiac collagen gene expression, we studied the effect of three different doses of angiotensin (12, 24, and 48 μg/kg/h) on adult heart and cultured neonatal cardiac fibroblasts. The steady-state mRNA abundance of collagen types I and III was monitored using Northern blot analysis in both left and right ventricular samples at day 3 of angiotensin infusion and in cultured cardiac fibroblasts stimulated with angiotensin. In all mRNA abundance studies, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) signal was used to normalize the data for possible differences in loading and/or transfer of total RNA. Both collagen types I/GAPDH and III/GAPDH mRNA signal ratios were increased significantly in left ventricle in all dose regimens used for angiotensin infusion. Only the collagen type I/GAPDH mRNA signal ratio was increased in right ventricle with angiotensin infusion. Angiotensin (10−7-10−5 M) had no effect on the steady-state mRNA abundance of collagen genes in cultured neonatal cardiac fibroblasts after 24 h treatment in serum-free conditions. Our results confirm that infusion of angiotensin may upregulate steady-state collagen gene mRNA abundance in the heart. Angiotensin had no observable effect on collagen mRNA abundance in neonatal fibroblast culture. An explanation for the current results may be that angiotensin causes the release of undefined factors from cardiac myocytes, and that these secondary factors may be involved in either the activation of collagen gene transcription or in alteration of stability of collagen mRNA transcripts via a paracrine mechanism. Although our results indicate hemodynamic loading may potentiate the action of angiotensin, this scenario is unlikely as collagen type I gene expression was increased in the normotensive right ventricle.
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  • 37
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    Molecular and cellular biochemistry 148 (1995), S. 45-57 
    ISSN: 1573-4919
    Keywords: manganese ; superoxide dismutase ; gene expression ; hyperoxide lung injury ; nuclear factor kappa B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract TNFα and IL-1 each can activate NF-κB and induce gene expression of manganese superoxide dismutase (MnSOD), a mitochondrial matrix enzyme which can provide critical protection against hyperoxic lung injury. The regulation of MnSOD gene expression is not well understood. Since redox status can modulate NF-κB and potential κB site(s) exist in the MnSOD promoter, the effect of thiols (including NAC, DTT and 2-ME) on TNFα and IL-1 induced activation of NF-κB and MnSOD gene expression was investigated. Activation of NF-kB and increased MnSOD expression were potentiated by thiol reducing agents. In contrast, thiol oxidizing or alkylating agents inhibited both NF-κB activation and elevated MnSOD expression in response to TNFα or IL-1. Since protease inhibitors TPCK and TLCK can inhibit NF-κB activation, we also investigated the effect of these compounds on MnSOD expression and NF-κB activation. TPCK and TLCK each inhibited MnSOD gene expression and NF-κB activation. Since the MnSOD promoter also contains anAP-1 binding site, the effect of thiols and thiol modifying agents on AP-1 activation was investigated. Thiols had no consistent effect onAP-1 activation. Likewise, some of the thiol modifying compounds inhibited AP-1 activation by TNFα or IL-1, whereas others did not. Since diverse agents had similar effects on activation of NF-κB and MnSOD gene expression, we have demonstrated that activation of NF-κB and MnSOD gene expression are closely associated and that reduced sulfhydryl groups are required for cytokine mediation of both processes.
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  • 38
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    Molecular and cellular biochemistry 172 (1997), S. 47-57 
    ISSN: 1573-4919
    Keywords: smooth muscle ; gene transfer ; DNA ; RNA ; ribozyme ; liposome ; lipoxygenase ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Chemically synthesized hammerhead-type ribozymes targeted against the porcine leukocyte-type 12-lipoxygenase (LO) have been developed and studied. One chimeric ribozyme consists of DNA in the non-enzymatic portions, and RNA in the enzymatic core as well as two phosphorothioate internucleotide linkages at 3′ terminus. The second ribozyme consists of ribonucleotide sequences generated by in vitro transcription. In this chapter we describe methodologies to first analyze the ribozyme catalytic activity in vitro by studying cleavage of target RNA in vitro. The subsequent sections will describe how to target the catalytic ribozyme and deliver it to porcine vascular smooth muscle cells (PVSMC) by a liposome-mediated method. Finally ways to evaluate its activity to inhibit expression of the 12-LO mRNA will be presented. These results demonstrate the feasibility of using ribozymes as novel candidates for therapeutic agents to block specific gene expression in vascular cells.
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  • 39
    ISSN: 1573-4919
    Keywords: heart ; DNA ; library ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The availability of high quality cDNA libraries is often crucial to the successful identification and characterization of genes. The concepts and potential pitfalls of constructing cDNA libraries are presented. Various applications requiring high quality cDNA libraries are outlined, including large-scale single pass sequencing of cDNA clones to generate expressed sequence tags (ESTs) and differential screening of cDNA libraries. The usefulness of combining such approaches for the discovery of novel disease-related and cardiovascular-based ESTs (CVBest) is discussed.
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  • 40
    ISSN: 1573-4919
    Keywords: estrogen ; apolipoprotein ; gene expression ; mice ; atherosclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Estrogen protects against developing premature coronary artery disease.However, the mechanism of protective effects of estrogen still remainspoorly understood. One mechanism by which estrogen can have protectiveeffects apppears to be through modulation of plasma lipoproteins. We showedthat the mouse can be used as animal model to study estrogen-mediatedsynthesis and secretion of lipoproteins since, unlike the rat, the mousedoes not up-regulate LDL receptors (Srivastava et al. [4]). Since inbredstrains of mice differ in their genetic background and show differingresponsiveness to dietary lipids, we examined how various inbred strains ofmice respond to estradiol administration, and whether some mouse strainsshow responses similar to rats. 17b-estradiol was administered to male micefrom 15 different inbred strains, and the changes in plasma levels oflipids, apoB, apoAI, and apoE were examined. Total cholesterol decreased inall but one strain, apoAI levels decreased in all but 3 strains while apoBlevels and apoB/apoAI ratios increased in all but 2 strains, suggesting thatin contrast to rats, the apoB-containing lipoproteins increased relative toHDL in all strains of mice examined. Basal and estradiol-induced changes intotal cholesterol were significantly correlated with changes in apoAI, butnot apoB, reflecting the predominance of HDL over other lipoproteins inmouse plasma. The effects of estrogen on plasma apoE levels varied amongvarious inbred strains of mice tested. Plasma apoE levels increased in sevenstrains treated with estrogen, and remained unchanged in the rest. Toexamine whether changes of plasma apoproteins are associated with thechanges in the respective hepatic mRNA levels, apoAI, B and E mRNA werequantified by RNase protection assay. Hepatic apoE mRNA did not showcorrelation with either basal or post treatment plasma apoE levels in any ofthe strains. Similarly, most of the mouse strains did not show correlationof plasma apoAI and apoB levels with the corresponding hepatic mRNA levels.These results suggest that estrogen regulates plasma lipoproteinconcentrations primarily by posttranscriptional mechansims, and there werestrain-related differences in the estrogen-mediated regulation oflipoprotein metabolism.
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  • 41
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    Molecular and cellular biochemistry 176 (1997), S. 273-279 
    ISSN: 1573-4919
    Keywords: cardiac hypertrophy ; myosin heavy chain ; gene expression ; adrenergic system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Growth of the heart in hypertrophy is accompanied by changes in the phenotypic expression of cardiac genes. To explore the molecular basis of cardiac hypertrophy, we have analyzed the regulation of myosin heavy chain gene (MHC) expression. In one set of experiments, pressure overload on the rat heart was produced by constriction of the abdominal aorta. Changes in the α and β-MHC mRNA were then studied in overloaded hearts and following load removal. Pressure overload resulted in down-regulation of the α-MHC with corresponding up-regulation of the steady state level of β-MHC mRNA. Load removal (debanding) resulted in regression of cardiac hypertrophy and a rapid return of α-MHC mRNA to normal values. In contrast, the recovery in β-MHC mRNA was much slower to the extent that it remained substantially elevated compared to respective sham controls even after 7 weeks of post-debanding. These results suggest that putative load-related signals independently regulate two genes. Several lines of evidence indicate that adrenergic nervous system plays an important role in the induction and maintenance of cardiac hypertrophy and in the redistribution of myosin isoforms. We have analyzed the effect of cAMP inducing agents on the regulation of a-MHC gene in primary cultures of the fetal (18 day) rat cardiac myocyte. Inclusion of 8 Br-cAMP in the culture media increased the expression of α-MHC promoter/reporter construct comprising of 2.9 kb upstream sequence of the α-MHC gene. Several deletion mutations in the α- MHC gene promoter defined the cAMP responsive boundaries to be a 32 bp region comprising of -71 to -40 bp sequences. Deletion of this region resulted in loss of cAMP response as well as in basal expression of α-MHC promoter/reporter construct. These data suggest a role of β-adrenergic pathway in the modulation of α-MHC gene expression.
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  • 42
    ISSN: 1573-4919
    Keywords: cholesteryl ester ; CETP ; Caco-2 ; polymerase chain reaction ; gene expression ; mRNA ; alternative splicing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Cholesteryl ester transfer protein (CETP) is a plasma protein involved in the reverse cholesterol transport and expressed in several human tissues and cell lines. We studied CETP expression in Caco-2 cell line, a model of the human enterocyte epithelium. By reverse-transcriptase polymerase chain reaction, we could demonstrate that in basal condition Caco-2 cells have a low rate of expression of active CETP mRNA. Furthermore, we found that even in this cell line CETP mRNA alternative splicing occurs with deletion of exon 9 sequence. Densitometric analysis of the in vitro amplified fragments showed that under basal conditions about 60% of reverse transcribed CETP cDNA corresponds to exon 9-deleted transcripts. After challenge with 50 µM sodium oleate, there is a ∼2 fold increase in the transcription rate of the full-length CETP cDNA, as measured by competitive PCR, which is accompanied to an increased activity measured in the cell-conditioned medium. On the contrary, no significant change is seen in the amount of exon 9-deleted cDNA. Consequently, an inversion in the ratio of full-length and exon 9-deleted CETP cDNA is evident, suggesting that sodium oleate selectively enhances the expression of full-length CETP mRNA.
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  • 43
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; calmodulin ; spontaneous hypertensive rats ; rat kidney cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats ingested with saline was investigated. The alteration in regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb of open reading frame). Rats were freely given saline as drinking water for 7 days. Regucalcin mRNA levels in the kidney cortex were suppressed by saline ingestion. When calcium chloride (10 mg Ca/100 g body weight) was intraperitoneally administered to rats ingested with saline for 7 days, the effect of calcium administration to increase regucalcin mRNA levels was weakened by saline ingestion. Such effect was also seen by the administration of 2.5 and 5 mg Ca/100 g. Regucalcin mRNA levels in the kidney cortex of spontaneous hypertensive rats (SHR) were not appreciably increased by the administration of calcium (10 mg/100 g). Meanwhile, calcium content in the kidney cortex was significantly elevated by the administration of calcium (10 mg/100 g) to normal rats. This increase was weakened in saline-ingested rats. Moreover, Ca2+/calmodulin-dependent protein kinase activity in the cytosol of kidney cortex was significantly decreased by saline ingestion. These results suggest the possibility that saline ingestion-induced suppression of regucalcin mRNA expression in the kidney cortex is partly involved in the attenuation of Ca2+ signalling.
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  • 44
    ISSN: 1573-4919
    Keywords: microbodies ; diabetes mellitus ; steroid hormone receptor ; β-oxidation ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract To determine whether the increased fatty acid β-oxidation in the peroxisomes of diabetic rat liver is mediated by a common peroxisome proliferation mechanism, we measured the activation of long-chain (LC) and very long chain (VLC) fatty acids catalyzed by palmitoyl CoA ligase (PAL) and lignoceryl CoA ligase and oxidation of LC (palmitic acid) and VLC (lignoceric acid) fatty acids by isotopic methods. Immunoblot analysis of acyl-CoA oxidase (ACO), and Northern blot analysis of peroxisome proliferator-activated receptor (PPAR-α), ACO, and PAL were also performed. The PAL activity increased in peroxisomes and mitochondria from the liver of diabetic rats by 2.6-fold and 2.1-fold, respectively. The lignoceroyl-CoA ligase activity increased by 2.6-fold in diabetic peroxisomes. Palmitic acid oxidation increased in the diabetic peroxisomes and mitochondria by 2.5-fold and 2.7-fold, respectively, while lignoceric acid oxidation increased by 2.0-fold in the peroxisomes. Immunoreactive ACO protein increased by 2-fold in the diabetic group. The mRNA levels for PPAR-α, ACO and PAL increased 2.9-, 2.8- and 1.6-fold, respectively, in the diabetic group. These results suggest that the increased supply of fatty acids to liver in diabetic state stimulates the expression of PPAR-α and its target genes responsible for the metabolism of fatty acids.
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  • 45
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    Molecular and cellular biochemistry 201 (1999), S. 111-123 
    ISSN: 1573-4919
    Keywords: complement factor I ; TPA ; protein kinase C ; gene expression ; Hep G2 cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This study examined the role of the protein kinase C (PKC) signalling pathway in the regulation of expression of human complement factor I (CFI) gene. The production of CFI by Hep G2 cells was enhanced in a dose- and time-dependent fashion by 12-O-tetradecanoyl-1,2-phorbol 13-acetate (TPA), a potent PKC activator. 4α-phorbol didecanoate, an inactive phorbol ester, had no effect on CFI synthesis. The TPA-dependent increase in CFI secretion was correlated with an increase in CFI mRNA levels. Forskolin, a cAMP-inducing agent, augmented the TPA response. W7, an inhibitor of protein kinase A and genistein, an inhibitor of protein tyrosine kinase(s) both did not prevent the increase in CFI expression mediated by TPA. However, calphostin C, a specific inhibitor of PKC, abolished the TPA-induced increase in CFI mRNA levels. Down regulation of intracellular PKC levels by prior exposure of Hep G2 cells to a high concentration of TPA also blocked the increase in CFI mRNA levels induced by TPA suggesting that the TPA effects were mediated via activation of PKC. mRNA decay studies indicated that the half-life of CFI mRNA in TPA-induced cells was not significantly different from control. Nuclear run-on transcriptional assays on the other hand demonstrated that whereas the CFI gene is transcribed under basal conditions in Hep G2 cells, TPA induced a 3-4 fold increase in the transcription rate of CFI gene in 24 h. The transcription rate of GAPDH gene did not change, indicating that the effects were not general on gene transcription. Transient transfections of Hep G2 cells with chloramphenicol acetyltransferase reporter gene (CAT) constructs containing a series of sequential 5′ deletions of the CFI promoter and CAT assays showed that the sequence between -136 and -130, containing an AP-1 consensus sequence (TGAGTCA) was required for the TPA response. This observation was substantiated by the finding that mutation of this AP-1 site to TttaTCA or TtAtcCA abolished the TPA responsiveness. The enhancement of the activity of transfected chimeric CAT constructs by TPA was abrogated by calphostin C and by pyrrolidine dithiocarbamate (an inhibitor of NF-κB and AP-1 transactivation). These results indicate that TPA regulation of CFI gene requires PKC signalling and is mediated by via a TPA response element (TRE) in the CFI promoter region located at -136/-130 and involves the transactivation of AP-1 and NF-κB transcription factors. We suggest that PKC may be one of the intracellular pathways that control CFI gene expression and that cellular processes (involving growth factors, hormones, cytokines etc.) that activate PKC may upregulate the expression of the CFI gene.
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  • 46
    ISSN: 1573-4927
    Keywords: mutator ; transposable element ; alcohol dehydrogenase ; maize ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A secondary mutant, derived from an allele of maize alcohol dehydrogenase 1 (Adh1) carrying a Mutator transposable element (Mu1) in its first intron, was reported to exhibit a threefold decrease in ADH enzymatic activity and steady-state RNA levels compared to the original mutant. The original mutant,Adh1-S3034 (abbreviatedS3034), was previously characterized at the molecular level. The derivative, abbreviatedS3034b, has now been cloned; at the DNA sequence level the insertion and surroundingAdh1 sequences are indistinguishable fromS3034. Furthermore, in our lines there is no difference in relative ADH activities between products of the two putative alleles. A comparison of gene expression in heterozygotes obtained by crossing to different tester lines reveals a correlation between the measured decrease in levels of ADH polypeptide produced by the mutant allele and the background in which it is measured; this effect is distinct from any background-related variation in the expression of the progenitor allele. It does not appear to be attributable to alternative patterns of DNA modification. It appears to reflect a background-associated difference in the level of normalAdh1-RNA produced. Thus the previously reported distinction betweenS3034 andS3034b may be due to differences in the extent to which the mutant allele and a given genetic background interact to produce functionalAdh1-RNA.
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  • 47
    ISSN: 1573-4919
    Keywords: mitochondrial biogenesis ; cytochrome c oxidase ; mRNA quantitation ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Cytochrome c oxidase (COX), like other multi-subunit components of the respiratory chain, is controlled by both the nuclear and the mitochondrial genome. In order to find wether there is a close relationship between mRNAs encoded by the nucleus and by the mitochondrion, and between these mRNAs and enzyme activity, we compared six rat tissues (ventricle, liver, m. soleus, m. plantaris, and the white and red portions of m. gastrocnemius). We found a tenfold range for COX activity, a tenfold range for the contents of mRNA III (mitochondrial) and mRNA VIc (nuclear), a threefold range for total [poly(A)+] mRNA content and a sevenfold range for total RNA content in these tissues. The ratio of mRNA III to mRNA VIc was equal in each tissue, indicating the presence of a mechanism that coordinates the two genomes. There was a good correlation between mRNA content and COX activity (r = 0.78 for VIc, r = 0.77 for 111; p 〈 0.0001), demonstrating that the expression of this enzyme is mainly under pretranslational control.
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  • 48
    ISSN: 1573-4919
    Keywords: Rb and p53 genes ; gene expression ; colorectal cancers ; colon carcinoma cell lines ; cell cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract We have compared the expression of the retinoblastoma (Rb) and p53 genes in normal human fibroblasts, colon carcinoma cell lines, matched pairs of colorectal tumor tissues and adjacent normal mucosa and in synchronized human diploid fibroblast cell line W138. The increased expression of Rb and p53 RNA was observed in a majority of colorectal cancers in comparison to adjacent normal mucosa and is accompanied by proportional increase in the expression of histone H3 gene. The Rb and p53 RNA levels varied significantly between the various colon carcinoma cell lines. However, we found that the expression of Rb and p53 RNA is regulated differently in cell cycle synchronized normal human fibroblasts. The Rb mRNA level did not change with the position in the cell cycle and did not differ significantly whether the cells were serum deprived or in 10% serum. But p53 mRNA expression follows the same pattern as histone H3 mRNA.
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  • 49
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    Molecular and cellular biochemistry 135 (1994), S. 89-98 
    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.
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  • 50
    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.
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  • 51
    ISSN: 1573-4919
    Keywords: vasoactive intestinal peptide ; ulcerative colitis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The availability of colon provides a ready source of human neurons. Among the products of nerve cell bodies, vasoactive intestinal peptide is a neuropeptide that serves as a marker of non-adrenergic, non-cholinergic inhibitory nerves in colon. These nerves have been proposed to be involved in regulation of immune function, secretion, and smooth muscle function. In previous work, we identified decreased tissue levels of vasoactive intestinal peptide in a disorder of chronic colonic mucosal inflammation, ulcerative colitis. We hypothesized that diminished gene expression of vasoactive intestinal peptide could result in decreased tissue levels of this neuropeptide. Sigmoid colon was obtained at surgery from controls (n=6) and patients with ulcerative colitis (n=6). Vasoactive intestinal peptide mRNA was quantified by Northern blot hybridization and tissue levels of vasoactive intestinal peptide were determined by radioimmunoassay. Tissue vasoactive intestinal peptide was decreased only in the mucosalsubmucosal layer of ulcerative colitis (p=.02). There was a single 1.7 kbase vasoactive intestinal peptide transcript identified in both control colon and ulcerative colitis. Normalized vasoactive intestinal peptide mRNA levels were increased by 260% in ulcerative colitis compared to controls (p〈.01). These observations suggest that decreased vasoactive intestinal peptide gene expression or abnormal post-transcriptional processing are not primary defects in this disorder of chronic inflammation. The findings support the alternative hypothesis that axonal degeneration in ulcerative colitis could result in increased expression of neuronal vasoactive intestinal peptide mRNA.
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  • 52
    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.
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  • 53
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; insulin ; calcium ; gene expression ; rat liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of refeeding on the expression of Ca2+-binding protein regucalcin mRNA in the liver of fasted rats was investigated. When rats were fasted overnight, the hepatic regucalcin mRNA level was reduced about 70% of that in feeding rats. Refeeding produced a remarkable elevation of hepatic regucalcin mRNA level (about 150–170% of fasted rats). Liver regucalcin concentration was appreciably increased by refeeding, although it was not altered by fasting. The oral administration of glucose (2 g/kg body weight) to fasted rats caused a significant increase in hepatic regucalcin mRNA level. Moreover, hepatic regucalcin mRNA level was clearly elevated by a single subcutaneous administration of insulin (10 and 100 U/kg) to fasted rats. The hormonal effect was not further enhanced by the simultaneous administration of calcium chloride (250 mg Ca/kg) to fasted rats, although calcium administration stimulated regucalcin mRNA expression in the liver. The present study suggests that the expression of hepatic regucalcin mRNA stimulated by refeeding is significantly involved in the action of insulin and/or calcium as stimulating factors.
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  • 54
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    Molecular and cellular biochemistry 143 (1995), S. 67-71 
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; gene distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The existence and expression of gene encoding the Ca2+-binding protein regucalcin in various species and tissues were investigated with Southern and Northern hybridization analyses using regucalcin cDNA (0.9 kb of open reading frame). Genomic Southern hybridization analysis demonstrated that regucalcin gene was widely conserved among higher animals including human, monkey, rat, mouse, dog, bovine, rabbit and chicken. The gene was not found in yeast. The Northern blot analysis of poly (A)+RNAs extracted from the liver of various species showed that regucalcin mRNA was predominantly expressed in rat and mouse, although the expression was also seen in human, bovine and chicken. Furthermore, the enzyme-linked immunoadsorbent assay (ELISA) with rabbit-anti-regucalcin IgG indicated that hepatic regucalcin concentration was most pronounced in rat as compared with that of guinea pig, mouse and chicken. These observations show that the gene expression of regucalcin and its protein synthesis is unique in the liver of rats, suggesting the existence of a specific mechanism in demonstrating regucalcin synthesis from gene.
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  • 55
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    Molecular and cellular biochemistry 143 (1995), S. 137-141 
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; estrogen ; gene expression ; rat liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of nuclear receptor-related hormones on the expression of hepatic calcium-binding protein regucalcin mRNA in rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin cDNA (0.9 kb of open-reading frame). A single subcutaneons administration of 17β-estradiol (0.5, 1.0 and 2.0 mg/kg body weight) in rats induced a remarkable increase of regucalcin mRNA in liver; the level was about 200% of control at 24 h after the administration of 2.0 mg/kg. The increase showed about 350% even at 6 h after the administration. Meanwhile, hepatic regucalcin mRNA level was not appreciably altered by a single subcutaneous administration of thyroxine (T4) (20, 40 and 80 mg/kg) or hydrocortisone (10 and 30 mg/kg) in rats. The present study demonstrates that the expression of hepatic regucalcin mRNA is stimulated by estrogen action in the liver nuclei of rats.
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  • 56
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    Molecular and cellular biochemistry 144 (1995), S. 105-108 
    ISSN: 1573-4919
    Keywords: fatty acid synthase ; gene expression ; and thyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of triiodothyronine (T3) on regulation of fatty acid synthase in chicken liver was investigated. In hypothyroid animals, enzyme activity was about one half of that in euthyroid animals. T3 treatment increased the enzyme activity in hypothyroid animals. There is little difference in both the mRNA concentration and the transcription rate between euthyroid and hypothyroid animals. T3 treatment markedly decreased both the mRNA concentration and the transcription rate in euthyroid and hypothyroid animals. These results suggested that T3 maintained the normal level of enzyme expression primarily by stimulating the post-transcriptional step, while the transcription of the gene was inhibited by hyperthyroidism.
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  • 57
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    Molecular and cellular biochemistry 151 (1995), S. 55-60 
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium ; gene expression ; kidney damage ; rat kidney cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The alteration of Ca2+-binding protein regucalcin mRNA expression in the kidney cortex of rats administered cisplatin and cephaloridine, which can induce kidney damage, was investigated. Cisplatin (0.25, 0.5 and 1.0 mg/100 g body weight) or cephaloridine (25, 50 and 100 mg/100 g) was intraperitoneally administered in rats, and 1, 2 and 3 days later they were sacrificed. The alteration in serum findings after the administration of cisplatin (1.0 mg/100 g) or cephaloridine (50 and 100 mg/100 g) demonstrated chemically induced kidney damage; blood urea nitrogen (BUN) concentration increased markedly and serum inorganic phosphorus or calcium concentration decreased significantly. Moreover, the administration of cisplatin (1.0 mg/100 g) or cephaloridine (100 mg/100 g) caused a remarkable increase of calcium content in the kidney cortex of rats, indicating kidney damage. The expression of regucalcin mRNA in the kidney cortex was markedly reduced by the administration of cisplatin or cephaloridine in rats, when the mRNA levels were analyzed by Northern blotting using rat liver regucalcin cDNA (0.9 kb). The mRNA decreases were seen with the used lowest dose of cisplatin or cephaloridine. The present study clearly demonstrates that the mRNA expression of Ca2+-binding protein regucalcin in the kidney cortex of rats is decreased by chemically induced kidney damage.
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  • 58
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    Molecular and cellular biochemistry 155 (1996), S. 85-90 
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; rat hepatoma ; Morris hepatoma cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Whether the gene expression of hepatic Ca2+-binding protein regucalcin is altered in hepatomas was investigated. The change in regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb). Rat hepatoma was induced by continuous feeding of basal diet containing 0.06% 3′-methyl-4-dimethylaminoazobenzene (3′-Me-DAB). After 35 weeks feeding, rats were sacrificed, and the non-tumorous and tumorous tissues of the livers were removed. In individual rats, the regucalcin mRNA levels in the tumorous tissues were generally decreased in comparison with that of the non-tumorous tissues of the chemical-fed rats, although the chemical administration might decrease the mRNA expression in normal rat liver, suggesting that the chemical administration causes a suppresive effect on the mRNA expression. When the genomic DNA extracted from the liver tumorous tissues was digested with restriction enzymes (EcoRI, BamHI and HindIII) and analyzed by Southern blotting, no rear-ranged band was found in the regucalcin gene from the hepatoma. Interestingly, in the transplantable Morris hepatoma cells, the regucalcin mRNA was markedly expressed, while the albumin mRNA was expressed only slightly. The present study demonstrates that regucalcin mRNA is clearly expressed in the transformed cells (Morris hepatoma cells).
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  • 59
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    Molecular and cellular biochemistry 155 (1996), S. 105-111 
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; aldosterone ; estrogen ; dexamethasone ; gene expression ; rat kidney cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of various steroid hormones on the expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using rat liver regucalcin complementary DNA (0.9 kb of open-reading frame). Regucalcin mRNA was expressed in the kidney cortex but not the medulla. Rats received a single subcutaneous administration of steroid; the animals were sacrificed 60 min after the treatment of aldosterone (2.5, 5.0 and 10 μg/100 g body weight) or 6 h after the treatment of estrogen (17β-estradiol; 0.05, 0.1 and 0.2 mg/100 g), hydrocortisone (0.5, 1.0 and 3.0 mg/100 g) and dexamethasone (50, 100 and 150 μg/100 g). Regucalcin mRNA levels in the kidney cortex were clearly diminished by the administration of aldosterone or estrogen, while hydrocortisone administration had no effect. The administration of dexamethasone (100 μg/100 g) caused a remarkable increase of regucalcin mRNA levels in the kidney cortex. The dexamethasone-induced increase in regucalcin mRNA levels was completely blocked by the simultaneous administration of cycloheximide (150 μg/100 g), although the drug administration had no effect on the mRNA levels in control rats. Meanwhile, the dexamethasone administration did not cause an appreciable alteration of calcium content in the kidney cortex. The present study demonstrates that, of the various steroid hormones used, dexamethasone uniquely has a stimulatory effect on regucalcin mRNA expression in the kidney cortex of rats. The steroid effect may be mediated through a newly synthesized protein.
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  • 60
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    Molecular and cellular biochemistry 162 (1996), S. 139-144 
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; saline ingestion ; hypertensive rats ; kidney cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of adrenalectomy (ADX) or saline ingestion, which is a hypertensive factor, on the expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using rat liver regucalcin complementary DNA (0.9 kb of open-reading frame). Regucalcin mRNA was expressed in the kidney cortex but not the medulla. Rats were adrenalectomized, and 48 h later they were sacrificed. ADX caused a reduction of regucalcin mRNA levels in the kidney cortex, suggesting that adrenal glands participate in the regulation of the mRNA expression. This reduction was not restored by the subcutaneous administration of dexamethasone with an effective dose (1 mg/kg body weight), which can stimulate kidney regucalcin mRNA expression. Regucalcin mRNA levels in the kidney cortex of rats were markedly suppressed by the ingestion of saline for 7 days. The ADX-induced decrease of renal cortex regucalcin mRNA levels was not appreciably restored by saline ingestion. Moreover, regucalcin mRNA levels in the kidney cortex of spontaneous hypertensive rats (SHR) were clearly decreased as compared with that of control (Wistar-Kyoto) rats. Meanwhile, calcium content in the kidney cortex was not significantly decreased by ADX or saline ingestion. The present study suggests that the expression of regucalcin mRNA in the kidney cortex of rats is suppressed by saline administration.
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  • 61
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    Molecular and cellular biochemistry 167 (1997), S. 169-177 
    ISSN: 1573-4919
    Keywords: tamoxifen ; interferon ; gene expression ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The molecular basis for the enhanced growth inhibition of MCF-7 human breast cancer xenografts by a combination of human interferon-β (IFN-β) and tamoxifen was investigated. Treatment of MCF-7, MDA-MB-231, and BT-20 cells with the combination of IFN-β and tamoxifen resulted in enhanced antiproliferative effects in vitro. Treatment with the combination of IFN-β and tamoxifen enhanced the expression of several IFN-β-inducible genes in human breast carcinoma cell lines relative to levels induced by IFN-β alone. Tamoxifen alone did not induce transcription of IFN-stimulated genes (ISGs). Augmentation of ISG expression by the combination of IFN-β and tamoxifen was noted in breast tumor cell lines irrespective of their functional estrogen receptor (ER) status or their dependence on estradiol for growth, suggesting that upregulation of ISGs was independent of ER status. Enhancement of IFN-stimulated gene expression by tamoxifen occurred at the transcripti onal level. Expression of transfected reporter genes under the control of IFN-α/β regulated promoters was also enhanced in IFN-β and tamoxifen-treated cells. Similarly, transcriptional induction of chimeric reporter plasmids driven by an IFN-γ inducible promoter (GAS; IFN-γ activated site) was also enhanced by the combination of IFN-γ and tamoxifen. In tamoxifen treated cells, IFN-β and IFN-γ readily activated transcription factors ISGF-3 and GAF, respectively. Therefore, augmentation of ISG expression by tamoxifen is an early event in the antitumoral activity of this drug combination. (Mol Cell Biochem 167: 169-177, 1997)
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  • 62
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    Molecular and cellular biochemistry 104 (1991), S. 35-43 
    ISSN: 1573-4919
    Keywords: α1-adrenergic receptors ; β-adrenergic receptors ; cardiac muscle ; cell culture ; gene expression ; protein kinase C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The molecular mechanisms of cardiac myocyte growth are relevant to important problems in cardiovascular disease. A cell culture model has been developed to explore the role of adrenergic hormones in cardiac myocyte growth and gene expression. Activation of a cardiac myocyte α1-adrenergic receptor by catecholamines induces hypertrophic growth of neonatal rat cardiac myocytes and initiates selective increases in contractile protein gene transcription. These effects on growth and gene expression do not depend on contractile activity. The cardiac myocytes contain at least two subtypes of α1-adrenergic receptors and at least three isoforms of protein kinase C (PKC). A distinct α1 receptor subtype may mediate hypertrophy and gene transcription. Different isoforms of PKC are translocated to different intracellular sites on activation, and there is evidence that the β-PKC isoform may be an element in the signal transduction pathway from an α1 receptor at the surface to the cardiac myocyte nucleus. Growth regulation through a β-adrenergic receptor can also be demonstrated in the culture model. The growth response mediated through a β-adrenergic receptor differs in several respects from that transduced through an al adrenergic receptor.
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  • 63
    ISSN: 1573-4919
    Keywords: calreticulin ; gene expression ; steroid receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Calreticulin is a ubiquitously expressed Ca2+ binding protein of the endoplasmic reticulum which inhibits DNA binding and transcriptional activation by steroid hormone receptors. In this study the effects of calreticulin on tyrosine aminotransferase (TAT) gene expression in cultured McA–RH7777 hepatocytes was investigated. McA–RH7777 cells were stably transfected with calreticulin expression vector to generate cells overexpressing the protein. The transcriptional activity of the TAT gene, which is glucocorticoid–sensitive and cAMP–dependent, was investigated in the mock transfected McA–RH7777 and in cells overexpressing calreticulin (designated McA–11 and McA–17). In the presence of dexamethasone or the cAMP analog (CTP–cAMP) expression of the TAT gene was induced in mock transfected McA–RH7777 cells by approximately 4.5 and 5 fold, respectively. In McA–11 and McA–17 cells, overexpressing calreticulin, glucocorticoi ever, the CTP–cAMP–dependent expression of the TAT gene was not affected. The ability of calreticulin to inhibit glucocorticoid–sensitive TAT gene expression but not the cAMP–dependent expression of the gene suggests that the protein affects specifically the action of transcription pathways involving steroid receptors or transcription factors containing KxFF(K/R)R–like motifs. Calreticulin may play an important role in the regulation of glucocorticoid–sensitive pathway of expression of the hepatocytes specific genes during development.
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  • 64
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    Molecular and cellular biochemistry 172 (1997), S. 37-46 
    ISSN: 1573-4919
    Keywords: gene transfer ; gene expression ; adenovirus ; blood vessel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Adenovirus-mediated gene transfer is a promising method for studies of vascular biology and potentially for gene therapy. Intravascular approaches for gene transfer to blood vessels in vivo generally require interruption of blood flow and have several limitations. We have used two alternative approaches for gene transfer to blood vessels in vivo using perivascular application of vectors. First, replication-deficient adenovirus expressing nuclear-targeted bacterial b-galactosidase was injected into cerebrospinal fluid via the cisterna magna of rats. Leptomeningeal cells over the major arteries were efficiently transfected, and adventitial cells of large vessels and smooth muscle cells of small vessels were occasionally stained. When viral suspension was injected with the rat in a lateral position, the reporter gene was expressed extensively on the ipsilateral surface of the brain. Thus, adenovirus injected into cerebrospinal fluid provides gene transfer in vivo to cerebral blood vessels and, with greater efficiency, to perivascular tissue. Furthermore, positioning of the head may ‘target’ specific regions of the brain. Second, vascular gene delivery was accomplished by perivascular injection of virus in peripheral vessels. Injection of the adenoviral vector within the periarterial sheath of monkeys resulted in gene transfer to the vessel wall that was substantial in magnitude although limited to cells in the adventitia. Approximately20% of adventitial cells expressed the transgene, with no gene transfer to cells in the intima or media. These approaches may provide alternative approaches for gene transfer to blood vessels, and may be useful for studies of vascular biology and perhaps vascular gene therapy.
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  • 65
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    Molecular and cellular biochemistry 172 (1997), S. 111-120 
    ISSN: 1573-4919
    Keywords: differential display ; cardiac development ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract An estimated 15,000 different mRNA species are expressed in a typical mammalian cell. The differential expression of mRNAs in both a temporal and cell-specific manner determines the fate of the cell and creates the organism. Analysis of this differential gene expression has become a central aim of many laboratories attempting to understand the mechanisms underlying various biological processes. Currently, we are using a technique called differential display to analyze the differential expression of genes in cardiomyocytes. Differential display is a rapid and powerful technique that was introduced by Liang and Pardee in 1992. Since that time, it has been successfully applied by several groups, and it is quickly becoming a standard method for studying differential gene expression. Here, we present a detailed article discussing the differential display methodology and how we have utilized it to identify potential genes involved in cardiomyocyte proliferation. Furthermore, we have provided a list of materials and supplied examples of data obtained, in an effort to allow the reader to perform the technique with success in their own laboratory.
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  • 66
    ISSN: 1573-4919
    Keywords: plasminogen activators ; plasminogen activator inhibitors ; gene expression ; left ventricular hypertrophy ; pressure overload
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In the early stages of left ventricular hypertrophy (LVH) acute adaptive changes occur in the coronary vasculature as it remodels. Plasminogen activators (PAs) and inhibitors (PAIs) have the potential effects of proteolytic degradation that is relevant to tissue remodeling and angiogenesis. Our study focused on the possible roles of PAI-1, PAI-2, uPA and tPA in myocyte hypertrophy and angiogenesis in the early and late stages of pressure overload induced left ventricular hypertrophy (LVH). We divided seventeen adult swine, weighing 24.2 ± 6.5 kg, into four groups: control, sham-operated, early LVH and late heart failure LVH group. At surgery we placed a fixed constrictor on the ascending aorta immediately above the aortic valve. This increased LV systolic pressure from 133 ± 15 to 193 ± 24 mm Hg after the surgery. We subdivided the early group into groups of 3 animals each that we euthanized at 8, 24 and 72 h after operation and obtained heart samples for analysis. In the late heart failure group individual animals were euthanized at 55, 59, 62 and 72 days after the detection of congestive heart failure. We also obtained tissue samples from the control and sham-operated swine. Sections for histologic analysis were fixed in 10% buffered formalin. We isolated RNA, size fractionated it using 1% formaldehyde-agarose gel electrophoresis and then did Northern blots. The mRNAs from both PAI-1 and PAI-2 showed a remarkable increase at 8 and 24 h after acute aortic constriction and returned to control by 72 h. Regional differences showed that most of the increases were in the endocardium. Three animals in the late heart failure LVH group were determined to be in congestive heart failure at about 2 months after the onset of aortic constriction. In these animals PAI-1 and PAI-2 were increased in both the left and right ventricles but remained low in an animal of the same elevation in aortic pressure seen by the LV who did not have congestive failure. These data suggest that PA and PAI gene expressions change before morphologic changes occur in the early stages of developing LVH. Also at the time of onset of congestive heart failure this increased expression reappears. PAs and PA inhibitors mRNA levels vary in the different regions of the heart reflecting changing wall stresses. Thus, the PAs and PA inhibitors may play an important role in angiogenesis that occurs during the early stages of LVH. The increased expression in the late stage of LVH may reflect further changes in wall stresses since these animals also showed overt clinical signs of heart failure.
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  • 67
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    Molecular and cellular biochemistry 177 (1997), S. 1-6 
    ISSN: 1573-4919
    Keywords: gene expression ; mRNA secondary structure ; single tube RT-PCR ; TNF receptor I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The secondary structure of human tumor necrosis factor receptor I (TNFR-I) mRNA based on its lowest folding energy was predicted. Three combinations of primers selected from open-regions and four combinations of primers from closed-regions of TNFR-I mRNA structure were employed for single-tube reverse transcription-polymerase chain reaction (RT-PCR) for the determination of TNFR-I gene expression in U937 cell. All the primers were designed with the same criteria. However, the different primers generated distinct quantities of RT-PCR products from the same concentration of TNFR-I mRNA, implying that the determination of gene expression by RT-PCR was affected by the mRNA secondary structure. In addition, the sensitivity of the open-region RT-PCR was approximately one hundred-fold higher than that in the closed-regions of TNFR-I mRNA. The low efficiency of the closed-region RT-PCR was not correlated with the G/C content of the TNFR-I mRNA structure. These results suggest that consideration of the influence of intrinsic mRNA structure of a gene is essential prior to the determination of gene expression by quantitative RT-PCR, and this open-region strategy of primer design may yield an efficient primer for in vitro amplification of cDNA by RT-PCR.
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  • 68
    ISSN: 1573-4919
    Keywords: extremely low frequency magnetic fields ; gene expression ; neuron derived orphan receptor-1 ; signal transduction ; Chinese hamster ovary K1 cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Enhanced expression of neuron derived orphan receptor (NOR-1) gene was observed by exposure of Chinese hamster ovary K1 (CHO-K1) cells to an extremely low frequency magnetic field (ELFMF) of 50 Hz at 400 mT, but not at 5 mT. The enhanced expression, reaching the maximum at 6 h, was transient and reduced to the control level after exposure to 400 mT ELFMF for 24 h. The NOR-1 expression induced by treatment with forskolin and TPA was further enhanced by the simultaneous treatment with 400 mT ELFMF, in which the maximum response was at 3 h. The NOR-1 expression by these treatments was induced more earlier than that by 400 mT ELFMF alone. When cells were treated with an inhibitor of the protein kinase C (calphostin C or crocetin) and Ca2+ entry blockers (nifedipin and dantrolen) during the 400 mT ELFMF exposure, the enhanced NOR-1 expression was not observed. Exposure of CHO-K1 cells to the high-density 400 mT ELFMF may affect the signal transduction in the cells, resulting in the enhanced NOR-1 gene expression.
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  • 69
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    Molecular and cellular biochemistry 186 (1998), S. 43-51 
    ISSN: 1573-4919
    Keywords: myocardial ischemia ; gene expression ; growth factors ; phospholamban ; calsequestrin heat shock proteins ; preconditioning ; stunning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Brief periods of coronary occlusion render the affected myocardium more tolarant to the otherwise devastating effects of long coronary occlusion. Besides this phenomena, called ischemic preconditioning, short periods of ischemia cause a regional dysfunction, namely myocardial stunning. The molecular mechanisms of both syndromes are not very well understood. We therefore investigated the expression of genes which may be involved in cardioprotection or repair processes.Using our porcine model of ischemia and reperfusion we were able to show an induction of genes coding for transcription factors (proto-oncogenes), for proteins involved in repair processes (heat shock genes), for proteins implicated in the calcium homeostasis (calcium-handling genes) and for growth factors. We could show that the increased mRNA levels are due to an enhanced transcriptional activity and not to a prolonged half-life of the transcripts. The angiogenic growth factor vascular endothelial growth factor (VEGF) represents an exception. It exhibits - in addition to a HIF-motif (Hypoxia Inducible Factor) in its promoter/enhancer - a protein binding region in its 3′ UTR which when occupied renders the mRNA more stable. However to what extent the expression of the distinct genes contributes to the cardioprotective effect of ischemic preconditioning or myocardial stunning can only be presumed. Increased mRNA stability can be confered via adenosine which is produced during ischemia by ATP-breakdown. The demasking of unknown genes - via differential display reverse transcription polymerase chain reaction (DDRT-PCR) - should provide a more comprehensive view of the mechanisms underlying both processes.
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  • 70
    ISSN: 1573-4919
    Keywords: regucalcin ; Ca2+-binding protein ; protein kinase C ; Ca2+signaling ; gene expression ; H4-II-E hepatoma cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of hepatic Ca2+-binding protein regucalcin in the cloned rat hepatoma cells (H4-II-E) was investigated. The change in regucalcin mRNA levels was analyzed by Northern blotting using rat liver regucalcin complementary DNA (0.9 kb of open reading frame). Regucalcin mRNA was expressed in H4-II-E hepatoma cells. This expression was clearly stimulated in the presence of serum (10% fetal bovine serum). Bay K 8644 (2. 5 × 10-6 M), a Ca2+ channel agonist, significantly stimulated regucalcin mRNA expression in the absence or presence of 10% serum. Dibutyryl cyclic AMP (10-3 M) did not have a stimulatory effect on the regucalcin mRNA expression. The presence of phorbol 12-myristate 13-acetate (PMA; 10-6 M) or estrogen (10-8 M) caused a significant increase in regucalcin mRNA levels in the hepatoma cells cultured in serum-free medium, while insulin (5 × 10-9 M) or dexamethasone (10-6 M) had no effect. Bay K 8644-stimulated regucalcin mRNA expression in the hepatoma cells was completely blocked in the presence of trifluoperazine (10-5 M), an antagonist of calmodulin, or staurosporine (10-7 M), an inhibitor of protein kinase C. The stimulatory effect of PMA was clearly inhibited in the presence of stauroporine. The present study demonstrates that regucalcin mRNA is expressed in the transformed H4-II-E hepatoma cells, and that the expression is stimulated through Ca2+-dependent signaling factors.
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  • 71
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    Journal of bioenergetics and biomembranes 27 (1995), S. 407-414 
    ISSN: 1573-6881
    Keywords: Glycine decarboxylase ; mitochondria ; photorespiration ; gene expression ; light control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The four component proteins of the glycine decarboxylase multienzyme complex (the P-, H-, T-, and L-proteins) comprise over one-third of the soluble proteins in mitochondria isolated from the leaves of C3 plants. Together with serine hydroxymethyltransferase, glycine decarboxylase converts glycine to serine and is the site of photorespiratory CO2 and NH3 release. The component proteins of the complex are encoded on nuclear genes with N-terminal presequences that target them to the mitochondria. The isolated complex readily dissociates into its component proteins and reassociates into the intact complexin vitro. Because of the intimate association between photosynthesis and photorespiration, the proteins of the complex are present at higher levels in leaves in the light. The expression of these genes is controlled at the transcriptional level and the kinetics of expression are closely related to those of the small subunit of Rubisco. Deletion analysis of fusions between the promoter of the H-protein of the complex and the reporter gene β-glucuronidase in transgenic tobacco has identified a region responsible for the tissue specificity and light dependence of gene expression. Gel shift experiments show that a nuclear protein in leaves binds to this region. Glycine decarboxylase has proven to be an excellent system for studying problems in plant biochemistry ranging from protein-protein interactions to control of gene expression.
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  • 72
    ISSN: 1573-5117
    Keywords: Turbellaria ; Dugesia ; homeobox ; gene expression
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    Topics: Biology
    Notes: Abstract To identify potential pattern control and cell determination and/or differentiation genes in the freshwater planarian Dugesial (G.) tigrina, we searched for homeobox genes of different types in the genome of this primitive metazoan. We applied two basic approaches: 1) Screening the cDNA library with degenerate oligonucleotides corresponding to the most conserved amino acid sequence from helix-3 of the homeodomain of each family; and 2) PCR amplification of genomic DNA or cDNA, using two sets of degenerated oligonucleotides corresponding to helices 1 and 3 of the homeodomain or two specific domains of the POU family. Using the first strategy we have identified and characterized two tissue-specific cell determination and/or differentiation NK-type homeobox genes. Using the second strategy we have identified several homeobox genes that belong to the HOM/Hox, paired (prd) or POU families.
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  • 73
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    Plant molecular biology 37 (1998), S. 425-435 
    ISSN: 1573-5028
    Keywords: gene expression ; protein-DNA interaction ; plant ; stress ; seed development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phytohormone abscisic acid is probably present in all higher plants. This hormone is necessary for regulation of several events during seed development and for the response to environmental stresses such as desiccation, salt and cold. An important part of the physiological response to abscisic acid is achieved through gene expression. Here, we summarize the current knowledge of regulation of abscisic acid-induced transcription. The main focus is on a description of the known abscisic acid-responsive cis-elements, their properties and the possible transacting factors binding to the elements. Results have shown that cooperative action of cis-elements and the promoter configuraton is crucial for regulation by abscisic acid. Furthermore, several elements are organ- and species-specific. Recent studies of the chromatin structure of abscisic acid-responsive genes point to the importance of induction of transcription by coactivators or by phosphorylation/dephosphorylation of transcription factors. An interesting example of activation by a cofactor is the cooperative action between abscisic acid-signaling and the regulatory protein Viviparous 1 through the abscisic acid responsive element.
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  • 74
    ISSN: 1573-5028
    Keywords: alanine aminotransferase ; gene expression ; GUS expression ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone encoding alanine aminotransferase (AlaAT) has isolated from randomly sequenced clones derived from a cDNA library of maturing rice seeds by comparison to previously identified genes. The deduced amino acid sequence was 88% and 91% homologous to those of the enzymes from barley and broomcorn millet (Panicum miliaceum), respectively. Using this cDNA as a probe, we isolated and sequenced the corresponding genomic clone. Comparison of the sequences of the cDNA and the genomic gene revealed that the coding region of the gene was interrupted by 14 introns 66 to 1547 bp long. Northern and western blotting analyses showed that the gene was expressed at high levels in developing seeds. When the 5′-flanking region between −930 and +85 from the site of initiation of transcription was fused to a reporter gene for β-glucuronidase (GUS) and then introduced into the rice genome, histochemical staining revealed strong GUS activity in the inner endosperm tissue of developing seeds and weak activity in root tips. Similar tissue-specific expression was also detected by in situ hybridization. These results suggest that AlaAT is involved in nitrogen metabolism during the maturation of rice seed.
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  • 75
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    Plant molecular biology 39 (1999), S. 161-169 
    ISSN: 1573-5028
    Keywords: expansin ; fruit growth ; fruit softening ; gene expression ; Lycopersicon esculentum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract cDNA clones encoding homologues of expansins, a class of cell wall proteins involved in cell wall modification, were isolated from various stages of growing and ripening fruit of tomato (Lycopersicon esculentum). cDNAs derived from five unique expansin genes were obtained, termed tomato Exp3 to Exp7, in addition to the previously described ripening-specific tomato Exp1 (Rose et al. (1997) Proc Natl Acad Sci USA 94: 5955–5960). Deduced amino acid sequences of tomato Exp1, Exp4 and Exp6 were highly related, whereas Exp3, Exp5 and Exp7 were more divergent. Each of the five expansin genes showed a different and characteristic pattern of mRNA expression. mRNA of Exp3 was present throughout fruit growth and ripening, with highest accumulation in green expanding and maturing fruit, and lower, declining levels during ripening. Exp4 mRNA was present only in green expanding fruit, whereas Exp5 mRNA was present in expanding fruit but had highest levels in full-size maturing green fruit and declined during the early stages of ripening. mRNAs from each of these genes were also detected in leaves, stems and flowers but not in roots. Exp6 and Exp7 mRNAs were present at much lower levels than mRNAs of the other expansin genes, and were detected only in expanding or mature green fruit. The results indicate the presence of a large and complex expansin gene family in tomato, and suggest that while the expression of several expansin genes may contribute to green fruit development, only Exp1 mRNA is present at high levels during fruit ripening.
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  • 76
    ISSN: 1573-5028
    Keywords: UV-B ; soybean ; chalcone synthase ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By developing gene-specific RT-PCR and using filters to allow transmission down to 290 nm (UV-B+) or blocking all radiation below 320 nm (UV-B−), the effect of UV-B+ and UV-B− light on expression of each of the presently known seven members of soybean chalcone synthase (CHS) gene family in dark-grown seedlings was analyzed. Dark expression was detectable already in 18 h dark-germinating embryos, with progressive increases on successive days, suggesting that chs belongs to a class of genes expressed very early during germination, and that the expression at this stage is either constitutive or induced by non-light-dependent factors present in the seed or made available following imbibition. Exposure of 18 h dark-germinating embryos to UV-B− or to UV-B+ light did not lead to an increase in chs signal. However, the 24 h dark-germinating embryos showed a distinct effect of UV-B+, interestingly coinciding with the stage when the head of seedlings was in the process of being pushed up above ground by stem elongation, suggesting the possibility of a developmental switch modulating the appearance of UV-B response. The response to UV-B− was most prominent in chs1 and almost silent in chs2, while the up-regulation by UV-B+ was most prominent in chs5 and chs6 and much less so in chs2. Interestingly, chs2 was noted to be the only member of the Gmchs gene family devoid of H-box, raising the possibility that the H-box may be a good indicator of the photo-inducibility of a chs gene.
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  • 77
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    Journal of bioenergetics and biomembranes 29 (1997), S. 109-119 
    ISSN: 1573-6881
    Keywords: ETS domain ; gene expression ; mammalian cells ; mitochondria ; nuclear respiratory factors ; oxidative phosphorylation ; regulation ; respiratory chain ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The majority of gene products required for mitochondrial respiratory function are encoded in the nuclear genome. These include most of the respiratory subunits and all of the proteins that regulate the mitochondrial genetic system. One approach to understanding nucleo-mitochondrial interactions in mammalian cells is to identify the nuclear transcription factors that are common to the expression of these gene products. This has led to the purification and molecular cloning of nuclear respiratory factors, NRF-1 and NRF-2. The DNA binding and transcriptional specificities of these proteins have implicated them in the expression of many respiratory subunits along with key components of the mitochondrial transcription, replication, and heme biosynthetic machinery. In addition, tissue-specific transcription factors have been linked to the coordinate synthesis of contractile proteins and muscle-specific respiratory subunits whereas other more ubiquitous factors may have a dual function in nuclear and mitochondrial gene activation. These findings provide a framework for further investigations of the nuclear genetic mechanisms that integrate the expression of the respiratory apparatus with that of other cellular systems during growth and development.
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    Journal of bioenergetics and biomembranes 31 (1999), S. 467-473 
    ISSN: 1573-6881
    Keywords: Uncoupling proteins ; fatty acids ; skeletal muscle ; brown adipose tissue ; obesity ; thermogenesis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The recently discovered uncoupling protein 3 (UCP3) is highly homologous to the mitochondrialinner membrane protein UCP1, which generates heat by uncoupling the respiratory chainfrom oxidative phosphorylation. The thermogenic function of UCP1 protects against cold andregulates the energy balance in rodents. We review in vitro studies investigating the uncouplingactivity of UCP3 and in vivo studies, which address UCP3 gene expression in brown adiposetissue and skeletal muscle under various metabolic conditions. The data presented are, for themost, consistent with an uncoupling role for UCP3 in regulatory thermogenesis. We alsodiscuss mediators of UCP3 regulation and propose a potential role for intracellular fatty acidsin the mechanism of UCP3 modulation. Finally, we hypothesize a role for UCP3 in themetabolic adaptation of the mitochondria to the degradation of fatty acids.
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  • 79
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    Journal of bioenergetics and biomembranes 26 (1994), S. 301-310 
    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.
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  • 80
    ISSN: 1573-6881
    Keywords: NADH-quinone oxidoreductase ; Paracoccus denitrificans ; gene cluster ; H+ pump ; gene expression ; FMN ; iron-sulfur cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract A comparison of the mitochondrial NADH-ubiquinone oxidoreductase and the energy-transducing NADH-quinone oxidoreductase (NDH-1) ofParacoccus denitrificans revealed that both systems have similar electron-transfer and energy-transduction pathways. In addition, both complexes are sensitive to the same inhibitors and contain similar electron carriers, suggesting that theParacoccus NDH-1 may serve as a useful model system for the study of the human enzyme complex. The gene cluster encoding theParacoccus NDH-1 has been cloned and sequenced. It is composed of 18,106 base pairs and contains 14 structural genes and six unidentified reading frames (URFs). The structural genes, URFs, and their polypeptides have been characterized. We also discuss nucleotide sequences which are believed to play a role in the regulation of the NDH-1 gene cluster andParacoccus NDH-1 subunits which may contain the binding sites of substrates and/or electron carriers.
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  • 81
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    Neuroscience and behavioral physiology 27 (1997), S. 245-249 
    ISSN: 1573-899X
    Keywords: Learning ; memory ; gene expression ; genetic methods ; mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Published data demonstrating the direct involvement of the genome in processes associated with learning are presented. These processes include the intensification of protein and RNA synthesis during learning and induction of early gene expression during learning. The relationship between consolidation of memory traces and protein synthesis is discussed. Along with different types of memory needing induction of gene expression for consolidation, some types of long-term memory are independent of protein synthesis. The use of genetic methods for studying the mechanisms of learning and memory is discussed.
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  • 82
    ISSN: 1573-8469
    Keywords: quorum-sensing ; gene expression ; autoinducer ; secondary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract N-acyl homoserine lactones (AHLs) function as cell density (quorum) sensing signals and regulate diverse metabolic processes in several gram negative bacteria. We report that strains of Pseudomonas syringae pvs. syringae (Pss), tabaci and tomato as well as P. corrugata and P. savastanoi produce difussible AHLs that activate the lux operons of Vibrio fischeri or the tra::lacZ fusion of Agrobacterium tumefaciens. In Pss strain B3A, AHL production occurs in cell density dependent manner. Nucleotide sequence and genetic complementation data revealed the presence of ahlIPss, a luxI homolog within the Ahl+ DNA of Pss strain B3A. The $$ahlI_{Pss}^ + $$ DNA expresses in AHL-deficient strains of P. fluorescens and E. carotovora subsp. carotovora (Ecc), and restores extracellular enzyme production and pathogenicity in the Ecc strain. The derivatives of Pss strains B3A and 301D carrying chromosomal ahlI::lacZ do not produce AHL, but like their wild type parents, produce extracellular protease and the phytotoxin syringomycin as well as elicit the hypersensitive reaction in tobacco leaves. While these strains also produce a basal level of β-galactosidase activity, the expression of ahlI::lacZ is substantially stimulated in the presence of multiple copies of the $$ahlI_{Pss}^ + $$ DNA or by the addition of cell-free spent cultures containing AHL. The activation of β-galactosidase production occurs with spent cultures of some, but not all Pseudomonas strains which produce AHL as indicated by the Lux and tra::lacZ assays. Pss strains deficient in the global regulatory genes, gacA or lemA, produce very low levels of AHL. Since inactivation of ahlIPss eliminates AHL production and since Ahl+ Pseudomonas strains carry the homolog of ahlIPss, we conclude that ahlIPss specifies a key step in AHL biosynthesis and it has been conserved in many plant pathogenic pseudomonads.
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    Antonie van Leeuwenhoek 62 (1992), S. 131-153 
    ISSN: 1572-9699
    Keywords: mitochondrial DNA ; mutational analysis ; nucleo-mitochondrial interactions ; gene expression ; membrane assembly ; respiratory deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In contrast to most other organisms, the yeastSaccharomyces cerevisiae can survive without functional mitochondria. This ability has been exploited in genetic approaches to the study of mitochondrial biogenesis. In the last two decades, mitochondrial genetics have made major contributions to the identification of genes on the mitochondrial genome, the mapping of these genes and the establishment of structure-function relationships in the products they encode. In parallel, more than 200 complementation groups, corresponding to as many nuclear genes necessary for mitochondrial function or biogenesis have been described. Many of the latter are required for post-transcriptional events in mitochondrial gene expression, including the processing of mitochondrial pre-RNAs, the translation of mitochondrial mRNAs, or the assembly of mitochondrial translation products into the membrane. The aim of this review is to describe the genetic approaches used to unravel the intricacies of mitochondrial biogenesis and to summarize recent insights gained from their application.
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    Antonie van Leeuwenhoek 65 (1994), S. 331-347 
    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.
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    Biodegradation 3 (1992), S. 125-135 
    ISSN: 1572-9729
    Keywords: natural evolution ; directed evolution ; biodegradation ; environmental pollutants ; environmental signal transduction ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microorganisms in nature are largely responsible for the biodegradation and removal of toxic and non-toxic chemicals. Many organisms are also known to have specific ecological niches for proliferation and colonization. The nature of the environment dictates to a large extent the biodegradability of synthetic compounds by modulating the evolutionary processes in microorganisms for new degradative genes. Similarly, environmental factors often determine the extent of microbial gene expression by activating or repressing specific gene or sets of genes through a sensory signal transduction process. Understanding how the environment modulates microbial activity is critical for successful bioremediative applications.
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    Biodegradation 3 (1992), S. 219-238 
    ISSN: 1572-9729
    Keywords: cellulase ; gene expression ; lignin ; Phanerochaete chrysosporium ; Streptomyces cyaneus ; xylanase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Lignocellulose is the predominant renewable resource. It uses include fuel, as the feedstock for the pulp and paper industry, and for animal nutrition. It also constitutes a large proportion of agricultural and urban waste. Biotechnology has roles in its efficient production and utilisation. The types of lignin substrates available for study of lignin biodegradation are described. The white rot fungus Phanerochaete chrysosporium is the archetypal system for the study of lignocellulose degradation, since it mineralises lignin and degrades both cellulose and hemicellulose. The salient features of the P. chrysosporium system are described. The lignin peroxidases are a family of proteins, and it is shown that expression of their genes is differential. P. chrysosporium is heterokaryotic with two gene equivalents that have abundant RFLPs. A set of basidiospore-derived strains with genetic compositions defined by such RFLPs provided the potential basis for a strain improvement programme for lignin degradation. However, analysis of this system using radiolabelled synthetic lignin (DHP) as the substrate confirmed previous evidence that both the substrate and the fungal cultures displayed much variation, so that it was difficult to quantify performance for this property. The cellobiohydrolase I enzymes are also coded for by a family of genes, and evidence is also presented for allelic variants, for differential expression and for differential splicing. In contrast, the cellobiohydrolase II function is encoded at a unique genetic locus. Approaches to an homologous integrative transformation system are discussed. Some actinomycete bacteria represent an alternative system for lignin solubilisation in which strains differ in their spectra of activities on lignocellulose substrates. The xylanase system of Streptomyces cyaneus is shown to include three enzymes, two of which are inducible by xylan. A novel assay method was developed and used to demonstrate that the third is constitutive and also non-repressible by glucose. It is proposed that this acts as a sensor for xylans in the environment that can yield breakdown products that are taken up and can then act as inducers of the other two enzymes. The studies on microbial lignocellulose degradation from different laboratories have allowed the formulation of specific biotechnological goals, and some of the problems and opportunities in this area are identified.
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  • 87
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    Antonie van Leeuwenhoek 62 (1992), S. 63-78 
    ISSN: 1572-9699
    Keywords: biogenesis ; gene expression ; mutants ; peroxisomes ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The observation that peroxisomes ofSaccharomyces cerevisiae can be induced by oleic acid has opened the possibility to investigate the biogenesis of these organelles in a biochemically and genetically well characterized organism. Only few enzymes have been identified as peroxisomal proteins inSaccharomyces cerevisiae so far; the three enzymes involved in β-oxidation of fatty acids, enzymes of the glyoxylate cycle, catalase A and the PAS3 gene product have been unequivocally assigned to the peroxisomal compartment. However, more proteins are expected to be constituents of the peroxisomes inSaccharomyces cerevisiae. Mutagenesis ofSaccharomyces cerevisiae cells gave rise to mutants unable to use oleic acid as sole carbon source. These mutants could be divided in two groups: those with defects in structural genes of β-oxidation enzymes (fox-mutants) and those with defects in peroxisomal assembly (pas-mutants). All fox-mutants possess morphologically normal peroxisomes and can be assigned to one of three complementation groups (FOX1, 2, 3). All three FOX genes have been cloned and characterized. The pas-mutants isolated are distributed among 13 complementation groups and represent 3 different classes: peroxisomes are either morphologically not detectable (type I) or present but non-proliferating (type II). Mislocalization concerns all peroxisomal proteins in cells of these two classes. The third class of mutants contains peroxisomes normal in size and number, however, distinct peroxisomal matrix proteins are mislocalized (type III). Five additional complementation groups were found in the laboratory of H.F. Tabak. Not all PAS genes have been cloned and characterized so far, and only for few of them the function could be deduced from sequence comparisons. Proliferation of microbodies is repressed by glucose, derepressed by non-fermentable carbon sources and fully induced by oleic acid. The regulation of four genes encoding peroxisomal proteins (PAS1, CTA1, FOX2, FOX3) occurs on the transcriptional level and reflects the morphological observations: repression by glucose and induction by oleic acid. Moreover, trans-acting factors like ADR1, SNF1 and SNF4, all involved in derepression of various cellular processes, have been demonstrated to affect transcriptional regulation of genes encoding peroxisomal proteins. The peroxisomal import machinery seems to be conserved between different organisms as indicated by import of heterologous proteins into microbodies of different host cells. In addition, many peroxisomal proteins contain C-terminal targeting signals. However, more than one import route into peroxisomes does exist. Dissection of the import mechanism in a genetically well suited organism likeSaccharomyces cerevisiae together with further characterization and functional assignment of the PAS gene products will provide insight into the biogenesis of peroxisomes. Moreover, these studies will lead to a good model system for elucidation of the mechanisms underlying human peroxisomal disorders.
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  • 88
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    Antonie van Leeuwenhoek 65 (1994), S. 245-250 
    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.
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  • 89
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    Antonie van Leeuwenhoek 66 (1994), S. 151-164 
    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.
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  • 90
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    Antonie van Leeuwenhoek 67 (1995), S. 181-200 
    ISSN: 1572-9699
    Keywords: β-lactam antobiotics ; biosynthetic enzymes ; penicillin ; cephalosporin ; cephamycin ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genespcbAB,pcbC andpenDE encoding enzymes involved in the biosynthesis of penicillin have been cloned fromPenicillium chrysogenum andAspergillus nidulans. They are clustered in chromosome I (10.4 Mb) ofP. chrysogenum, but they are located in chromosome II ofPenicillium notatum (9.6 Mb) and in chromosome VI (3.0 Mb) ofA. nidulans. Expression studies have shown that each gene is expressed as a single transcript from separate promoters. Enzyme regulation studies and gene expression analysis have provided useful information to understand the control of gene expression leading to overexpression of the genes involved in penicillin biosynthesis. Cephalosporin genes have been studied inCephalosporium acremonium and also in cephalosporin-producing bacteria. InC. acremonium the genes involved in cephalosporin biosynthesis are separated in at least two clusters. Cluster I (pcbAB-pcbC) encodes the first two enzymes of the cephalosporin pathway which are very similar to those involved in penicillin biosynthesis. Cluster II (cefEF-cefG), encodes the last three enzymatic activities of the cephalosporin pathway. It is unknown, at this time, if thecefD gene encoding isopenicillin epimerase is linked to any of the two clusters. In cephamycin producing bacteria the genes encoding the entire biosynthetic pathway are located in a single cluster extending for about 30 kb inNocardia lactamdurans, and inStreptomyces clavuligerus. The cephamycin clusters ofN. lactamdurans andS. clavuligerus include a genelat which encodes lysine-6-aminotransferase an enzyme involved in formation of the precursor α-aminoadipic acid. TheN. lactamdurans cephamycin cluster includes, in addition, a β-lactamase (bla) gene, a penicillin binding protein (pbp), and a transmembrane protein gene (cmcT) that is probably involved in secretion of the cephamycin. Little is known however about the mechanism of control of gene expression in the different β-lactam producers. The availability of most of the structural genes provides a good basis for further studies on gene expression. This knowledge should lead in the next decade to a rational design of strain improvement procedures. The origin and evolution of β-lactam genes is intriguing since their nucleotide sequences are extremely conserved despite their restricted distribution in the microbial world.
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  • 91
    ISSN: 1572-9699
    Keywords: Campylobacter jejuni ; flagella ; flagellin genes ; flaA ; flaB ; phase variation ; gene expression ; sigma 28 ; sigma 54 ; repressor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Flagella production inCampylobacter jejuni 81116 is subject to phase variation; the bacterium is able to switch its flagellum synthesis, and thereby its motility, on and off. Under standard laboratory growth conditions flagellar phase variants can be maintained as stable, pure cultures. We found conditions that efficiently induced a phase shiftin vitro. TheflaA gene but not theflaB gene is subject to the on and off switch. Minor amounts of FlaB are still present in aflagellate cells. We previously showed that flagellin gene expression in phase variants was regulated at the transcriptional level. Here, sequence data prove that abolishment offlaA transcription is not caused by DNA rearrangements or mutations within the flagellin locus. SinceflaA is preceeded by a typical σ28 promoter aC. jejuni σ28 homolog could play a role in regulation offlaA gene expression but such a gene or protein could not be detected. However,in vitro transcription could be detected using σ28-holoenzyme preparations fromBacillus subtilis. Possible regulatory mechanisms that may control flagellar phase variation in Campylobacter are discussed.
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  • 92
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    Antonie van Leeuwenhoek 70 (1996), S. 129-145 
    ISSN: 1572-9699
    Keywords: gene expression ; gene regulation ; Lactococcus ; Lactobacillus ; Lactus acid bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Relatively recently, a number of genes and operons have been identified in lactic acid bacteria that are inducible and respond to environmental factors. Some of these genes/operons had been isolated and analysed because of their importance in the fermentation industry and, consequently, their transcription was studied and found to be regulatable. Examples are the lactose operon, the operon for nisin production, and genes in the proteolytic pathway of Lactococcus lactis, as well as xylose metabolism in Lactobacillus pentosus. Some other operons were specifically targetted with the aim to compare their mode of regulation with known regulatory mechanisms in other well-studied bacteria. These studies, dealing with the biosynthesis of histidine, tryptophan, and of the branched chain amino acids in L. lactis, have given new insights in gene regulation and in the occurrence of auxotrophy in these bacteria. Also, nucleotide sequence analyses of a number of lactococcal bacteriophages was recently initiated to, among other things, specifically learn more about regulation of the phage life cycle. Yet another approach in the analysis of regulated genes in the ‘random’ selection of genetic elements that respond to environmental stimuli and the first of such sequences from lactic acid bacteria have been identified and characterized. The potential of these regulatory elements in fundamental research and practical (industrial) applications will be discussed.
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  • 93
    ISSN: 1572-9699
    Keywords: Quorum sensing ; N-acylhomoserine lactones ; gene expression ; virulence ; secondary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although it has been clear for some time that individual bacterial cells employ intra-cellular signalling systems to sense, integrate and process information from their surroundings, their widespread capacity to perceive information from other bacterial cells is only just beginning to be recognised. Recent work has established that diverse bacteria exploit a cell-cell communication device to regulate the transcription of multiple target genes. This communication device termed ‘quorum sensing’, depends on the production of one or more diffusible signal molecules termed ‘autoinducers’ or ‘pheromones’ which enable a bacterium to monitor its own cell population density. Quorum sensing is thus an example of multicellular behaviour in prokaryotes and regulates diverse physiological processes including bioluminescence, swarming, antibiotic biosynthesis, plasmid conjugal transfer and the production of virulence determinants in animal, fish and plant pathogens. In Gram-negative bacteria, the best understood family of signal molecules are the N-acylhomoserine lactones (AHLs) which vary predominantly in the presence or absence of an acyl chain C3 substituent (oxo- or hydroxy-) and length of the N-acyl side chain. However not all quorum sensing signal molecules are AHLs; in Gram-positive bacteria, they are often post-translationally modified peptides. Irrespective of the chemical ‘language’ employed, interference with either the synthesis or transmission of a quorum sensing signal molecule in pathogenic bacteria offers an exciting new strategy for controlling infection.
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  • 94
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    Plant molecular biology reporter 16 (1998), S. 323-339 
    ISSN: 1572-9818
    Keywords: Aux/IAA genes ; gene expression ; gene families ; RT-PCR ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have developed an improved method for determination of gene expression levels with RT-PCR. The procedure is rapid and does not require extensive optimization or densitometric analysis. Since the detection of individual transcripts is PCR-based, small amounts of tissue samples are sufficient for the analysis of expression patterns in large gene families. Using this method, we were able to rapidly screen nine members of the Aux/IAA family of auxin- responsive genes and identify those genes which vary in message abundance in a tissue- and light-specific manner. While not offering the accuracy of conventional semi-quantitative or competitive RT-PCR, our method allows quick screening of large numbers of genes in a wide range of RNA samples with just a thermal cycler and standard gel analysis equipment.
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  • 95
    ISSN: 1573-1561
    Keywords: Danaus plexippus ; Danaus gilippus ; Syntomeida epilais ; Syntomis mogadorensis ; cardiac glycosides ; Na+,K+-ATPase ; target site modification ; insensitivity ; amino acid substitution ; sequestration ; gene expression ; site-directed mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The Monarch butterfly (Danaus plexippus) sequesters cardiac glycosides (CG) for its chemical defense against predators. Larvae and adults of this butterfly are insensitive towards dietary cardiac glycosides, whereas other Lepidoptera are sensitive and intoxicated by ouabain. Ouabain inhibits Na+,K+-ATPase by binding to its α-subunit. We have amplified and cloned the DNA-sequence encoding the respective ouabain binding site. Instead of the amino acid asparagine at position 122 in ouabain-sensitive insects, the Monarch has a histidine in the putative ouabain binding site, which consists of 12 amino acids. Starting with the CG-sensitive Na+,K+-ATPase gene fromDrosophila, we converted pos. 122 to a histidine residue as inDanaus plexippus by site-directed mutagenesis. Human embryonic kidney cells (HEK) (which are sensitive to ouabain) were transfected with the mutated Na+,K+-ATPase gene in a pSVDF-expression vector and showed a transient expression of the mutatedDrosophila Na+,K+-ATPase. When treated with ouabain, the transfected cells tolerated ouabain at a concentration of 50 mM, whereas untransformed controls or controls transfected with the unmutatedDrosophila gene, showed a substantial mortality. This result implies that the asparagine to histidine exchange contributes to ouabain insensitivity in the Monarch. In two other CG-sequestering insects, e.g.,Danaus gilippus andSyntomeida epilais, the pattern of amino acid substitution differed, indicating that the Monarch has acquired this mutation independently during evolution.
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  • 96
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    World journal of microbiology and biotechnology 11 (1995), S. 71-84 
    ISSN: 1573-0972
    Keywords: Archaea ; gene expression ; genetics ; replication ; thermophile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The molecular biology of extremophiles has recently attracted much interest, both in terms of cell adaptation to extreme environmental conditions and the development of manipulative genetic techniques. Although molecular genetic techniques have been successfully applied to halophiles and methanogens, their use with hyperthermophiles is limited by the extreme growth conditions that these organisms require. Much information on the thermophilic Archaea, has been obtained by studying the key enzymes involved in fundamental cell processes, such as transcription and replication, and by the cloning, sequence comparison and heterologous expression of structural genes. The development of viral vectors and systems for transformation, mutant production and screening will permit increased genetic manipulation of these organisms.
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  • 97
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    World journal of microbiology and biotechnology 12 (1996), S. 189-202 
    ISSN: 1573-0972
    Keywords: gene expression ; nodule development ; nodulin genes ; Rhizobium-legume symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Rhizobium, Bradyrhizobium and Azorhizobium can elicit the formation of N2-fixing nodules on the roots or stems of their leguminous host plants. The nodule formation involves several developmental steps determined by different sets of genes from both partners, the gene expression being temporally and spatially coordinated. The plant proteins that are specifically synthesised during the formation and function of the nodule are called nodulins. The nodulins that are expressed before the onset of N2 fixation are termed early nodulins. These proteins are probably involved in the infection process as well as in nodule morphogenesis rather than in nodule function. The nodulins expressed just before or during N2 fixation are termed late nodulins and they participate in the function of the nodule by creating the physiological conditions required for nitrogen fixation, ammonium assimilation and transport. In this review we will describe nodulins, nodulin genes and the relationship between nodulin gene expression and nodule development. The study of nodulin gene expression may provide insight into root-nodule development and the mechanism of communication between bacteria and host plant.
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  • 98
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    World journal of microbiology and biotechnology 9 (1993), S. 433-443 
    ISSN: 1573-0972
    Keywords: Alginate ; gene expression ; negative regulators ; positive regulators ; promoters ; Pseudomonas ; TOL plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Gene regulation studies in pseudomonad bacteria are mainly restricted to Pseudomonas aeruginosa and Pseudomonas putida. Constitutive promoters exhibit DNA sequences similar to the σ 70-dependent constitutive promoters of Escherichia coli. The TOL meta-cleavage pathway operon promoter and the nah operon promoters are the best characterized σ 70-dependent promoters, which exhibit-10 regions rich in As and Ts and non-conserved-35 regions. The DNA binding motif recognized by the respective positive regulators lies between-40 and-80. Another set of positively controlled promoters exhibit upstream activator sequences located between-100 and-500. Transcription stimulation from some of these promoters also involves σ 54 and/or IHF protein. In this class of promoters, DNA binding is required to establish open complexes. Promoters for the utilization of histidine (hut) are under negative control by the HutC protein. hut promoters exhibit-10/-35 consensus regions and an overlapping operator sequence between-15 and-50. Repression of hut promoters seems to be achieved through steric hindrance of RNA polymerase. Another set of promoters are controlled by catabolite repression, which seems to be cyclic-AMP independent.
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  • 99
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    World journal of microbiology and biotechnology 9 (1993), S. 461-467 
    ISSN: 1573-0972
    Keywords: Aspergillus nidulands ; catabolite repression ; gene expression ; penicillin ; Penicillium chrysogenum ; Plectomycetes ; regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Carbon catabolite repression and pH regulation are regulatory circuits with a wide domain of action in the Plectomycetes. Penicillin biosynthesis is one of the pathways which are under their control. The conclusions obtained so far, which are based on studies of the genetic and molecular regulation of the penicillin pathway of Aspergillus nidulans, would have been much harder to produce using an organism such as Penicillium chrysogenum (the industrial penicillin producer). However, A. nidulans and P. chrysogenum are close in terms of their phylogeny and one can reasonably predict that the conclusions about A. nidulans, which are summarized in this review and which are of unquestionable biotechnological relevance, will be extrapolable to the industrial organism.
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  • 100
    ISSN: 1573-0603
    Keywords: vaccinia virus ; orthopox virus ; recombination ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A basic technique is described for inserting any foreign gene into poxvirus by in vitro recombination. Also described is a method for identifying and plaque-purifying recombinant poxvirus containing the foreign gene using nitrocellulose filters and DNA hybridization. Immunologic techniques are presented for analyzing expression of the foreign gene, either on the surface membrane or inside infected cells.
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