ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • gene expression
  • Springer  (40)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • 1995-1999  (40)
  • 1990-1994
  • 1935-1939
  • 1998  (40)
Collection
Publisher
  • Springer  (40)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • Wiley-Blackwell  (9)
Years
  • 1995-1999  (40)
  • 1990-1994
  • 1935-1939
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    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
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 178 (1998), S. 157-162 
    ISSN: 1573-4919
    Keywords: protein tyrosine phosphatases ; gene expression ; degenerate deoxyoligonucleotides ; RT-PCR ; Swiss 3T3 fibroblasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The aim of this study was to identify protein tyrosine phosphatases (PTPs) expressed in Swiss 3T3 fibroblasts and to examine their expression levels as well as to characterize quantitative aspects of RT-PCR based on degenerate deoxyoligonucleotides. By using an RT-PCR assay based on degenerate deoxyoligonucleotide primers, expression of mRNAs for two cytoplasmic- and six transmembrane-type PTPs in Swiss 3T3 cells was detected. The sequences of two of them are new. Among nine analyzed PTPs expressed to widely varied extends, only three have mRNA levels high enough to be seen on Northern blots with 10 µg of total RNA per lane. The frequencies with which the examined PTPs are represented among the PCR amplification products, correlate stronger with the primer fidelity, defined as the number of mismatches between the primer- and the cDNA target-sequences, rather than with the PTP expression levels. In conclusion, an RT-PCR assay based on degenerate primers can be successfully used to sample the expressed PTPs and to identify new members of this gene family. However, reliable quantification of their mRNA levels can only be achieved using the classical approaches, like Northern, RNase protection assay or non-degenerate quantitative RT-PCR.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 178 (1998), S. 283-287 
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; fetal development ; rat liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of hepatic calcium-binding protein regucalcin mRNA in fetal rats was investigated. The alteration in regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin cDNA (0.9 kb with complete open reading frame). Hepatic regucalcin mRNA levels were progressively increased with fetal development; the mRNA was clearly expressed at 15 and 21 days of pregnancy but only slightly at the 8 days. Meanwhile, β-actin mRNA levels in the fetal liver were remarkable at 8 and 15 days of pregnancy. The fetal liver regucalcin mRNA levels at 15 days of pregnancy were significantly decreased by overnight-fasting of maternal rats. The oral administration of calcium chloride (50 mg Ca/100 g body weight) to maternal rats at 15 days of pregnancy caused a remarkable elevation (about 2 fold) of regucalcin mRNA levels in the fetal liver; this increase was seen 60 and 180 min after the calcium administration. After birth, regucalcin mRNA was increasingly expressed in the livers of newborn and weanling rats, while hepatic β-actin mRNA expression was not appreciably altered with increasing ages. These findings demonstrate that the expression of hepatic regucalcin mRNA is increased with fetal development, and that the gene expression may be stimulated by the ingestion of dietary calcium.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 188 (1998), S. 41-48 
    ISSN: 1573-4919
    Keywords: zinc ; transcription factors ; gene expression ; organogenesis ; Xenopus laevis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Zinc regulates the gene expression machinery. It affects the structure of chromatin, the template function of its DNA, the activity of numerous transcription factors and of RNA polymerases. Hence, it determines both the types of mRNA transcripts synthesized and the rate of transcription itself. Alterations in one or more of these zinc dependent processes have been proposed to account for the proliferative arrest and teratology induced by zinc deficiency. To examine this proposal, studies of zinc during X. laevis development have been initiated. The kinetics of X. laevis oocyte zinc uptake and storage and of zinc utilization during embryogenesis have been examined first. Vitellogenin carries zinc into the oocyte. Ten % of the total zinc (10 ng/egg) remains within the cytosol while 90% (90 ng/egg) is stored in the yolk platelets associated with lipovitellin. The cytosolic pool is the source of the zinc for all newly formed metalloproteins involved in embryo development. The yolk platelet zinc pool is stored for later use during early metamorphosis. It is now possible to examine zinc transfer to molecules, such as e.g. transcription factors, and the role of the metal in their function in development and organogenesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 189 (1998), S. 107-111 
    ISSN: 1573-4919
    Keywords: gene expression ; electromagnetic fields ; superinduction ; anisomycin ; immediate early gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Rat pheochromocytoma PC12 cells have been treated with nerve growth factor (NGF) at final concentrations of 2, 4, 8, and 16 ng/ml, and then were exposed to 60-Hz, sinusoidal magnetic fields (MF) of 12.5, 25, 50, and 100 μT (rms) for 30 min. Transcript levels for both c-fos and glyceraldehyde-3 -phosphate dehydrogenase were determined by Northern blot analysis using 32P-labeled cDNA probes. No change in c-fos expression was measured at any condition employed. Treatment of PC12 cells with a combination of agents (NGF, forskolin, and tetradecanoylphorbol acetate [TPA]) increased c-fos expression over that detected with NGF alone. MF exposure of cells treated with the three-agent regimen produced two outcomes, either no change or a doubling of c-fos expression. In subsequent experiments, cells were treated with NGF, NGF + forskolin + TPA, or pre-treated with anisomycin and then treated with NGF + forskolin + TPA. It was determined that MF exposure, like superinduction with anisomycin, increased c-fos expression only in cultures which were not yet exhibiting maximal c-fos expression. It is hypothesized that MF exposure, like anisomycin, may alter the activity of key intracellular protein kinases.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1573-4978
    Keywords: gene expression ; nuclear matrix proteins ; ocular lens epithelial cells ; transcription factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Association of transcription factors with the nuclear matrix represents a mechanism by which nuclear architecture may influence transcriptional control of gene expression. This investigation examines nuclear matrix associated proteins (NMP's) isolated from ocular lens epithelial cells by monitoring DNA binding activities using consensus oligonucleotides recognized by the transcription factors YY1, AML-1, AP-1, SP-1 and ATF. The nuclear matrix fractions tested included an immortilized human lens epithelial cell line containing the SV40 large T-antigen, and two mouse lens epithelial cell lines derived from either a normal mouse or a cataract mouse. A rabbit epidermal epithelial cell line and HeLa cells were also included in this study for comparison. The data from these experiments reveal that ubiquitously represented and tissue restricted regulatory proteins are associated with nuclear matrix of lens epithelial cells. The functional significance of the nuclear matrix association of these transcription factors remains to be determined. However, our findings raise the possibility that the transcription factors associated with the nuclear matrix could have specific roles in gene regulation and eye tissue development.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    ISSN: 1573-9368
    Keywords: transgenic mice ; gene expression ; mammary gland ; co-injection ; milk protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In an attempt to enhance the frequency and level of expression of a poor-performing MMTV-driven transgene, we co-integrated this construct with the ovine β-lactoglobulin (BLG) gene in transgenic mice. Seven lines of transgenic mice possessing co-integrated BLG and MMTV-RZ5 transgenes were compared with 12 lines of mice that possessed only the MMTV-RZ5 construct. Co-integration enhanced the frequency of expression in the mammary gland from two out of 12 lines for the MMTV-RZ5 transgene alone, to five out of seven when co-integrated with BLG. Surprisingly, co-integration also resulted in co-expression of the two transgenes in the salivary gland, lung and spleen in addition to the mammary gland. Furthermore, both transgenes were expressed in virgin animals, and throughout pregnancy and lactation, suggesting that the developmental regulation of the locus follows that of the MMTV-promoter. These findings represent a novel locus control property of the ovine BLG gene that confer s commitment of the locus to the mammary gland, but also to a range of heterogeneous tissues possibly defined by the second promoter at the locus
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 1573-9368
    Keywords: transgenic rabbits ; gene expression ; mammary gland ; erythropoietin ; WAP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An understanding of the expression of transgenes in the mammary gland during gestation and lactation is crucial for the use of transgenic mammals as bioreactors. Here we describe the temporal pattern of expression of the endogenous rabbit WAP gene and human erythropoietin (hEPO) transgenes under the control of rabbit WAP promoter and 3′ flanking sequences. The endogenous rabbit WAP gene was expressed throughout gestation including the day of mating, as well as during lactation in transgenic rabbits bearing a minigene construct. In non-pregnant cycling females, WAP expression was found independent of transgenic status; however, WAP expression was not detected in non-cycling females. The significance of this new finding is not clear at present. hEPO mRNA was detected in mammary gland biopsies from pregnant transgenic rabbits only on day 28 of gestation. During lactation, transcripts were present in mammary gland biopsy samples taken on days 0, 7, 14 and 21. A sharp decline in the levels ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    ISSN: 1572-9788
    Keywords: differential display ; gene expression ; hybrid vigor ; molecular marker heterozygosity ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Using differential display analysis, we assessed the patterns of differential gene expression in hybrids relative to their parents in a diallel cross involving 8 elite rice lines. The analysis revealed several patterns of differential expression including: (1) bands present in one parent and F1 but absent in the other parent, (2) bands observed in both parents but not in the F1, (3) bands occurring in only one parent but not in the F1 or the other parent, and, (4) bands detected only in the F1 but in neither of the parents. Relationships between differential gene expression and heterosis and marker heterozygosity were evaluated using data for RFLPs, SSRs and a number of agronomic characters. The analysis showed that there was very little correlation between patterns of differential expression and the F1 means for all six agronomic traits. Differentially expressed fragments that occurred only in one parent but not in the other parent or in F1 in each of the respective crosses were positively correlated with heterosis and heterozygosity. And conversely, fragments that were detected in F1s but in neither of the respective parents were negatively correlated with heterosis and heterozygosity. The remaining patterns of differential expression were not correlated with heterosis or heterozygosity. The relationships between the patterns of differential expression and heterosis observed in this study were not consistent with expectations based on dominance or overdominance hypotheses.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 36 (1998), S. 439-449 
    ISSN: 1573-5028
    Keywords: ethylene ; gene expression ; leaf senescence ; RNase ; tomato ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A main feature of leaf senescence is the hydrolysis of macromolecules by hydrolases of various types, and redistribution of released materials. We have initiated a study for the characterization of RNases involved in nucleic acid catabolism during senescence. Using a PCR-based cloning approach we isolated from tomato two senescence-induced RNase cDNA clones. Each of these cDNAs hybridized to a senescence-induced transcript in northern analysis. One RNase cDNA was identical to the tomato LX RNase while the second corresponded to the LE RNase. Both LX and LE RNase genes had originally been demonstrated to be induced after phosphate starvation of tomato cell culture but nothing was known about their expression or function in plants. We observed that the expression of the LX and LE genes is induced in leaves during an advanced stage of senescence with the LX transcript level being much more induced than that of LE. Low-level expression of the RNase genes was observed in flowers and artificially senescing detached leaves while no expression could be detected in stems, roots, or fruits at different ripening stages. Ethylene activated the LX gene expression in detached young leaves while LE gene expression, which could be transiently induced by wounding, appeared to be activated by abscisic acid. We suggest that the LX RNase has a role in RNA catabolism in the final stage of senescence, and LE may function during wounding as a plant defense protein.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 36 (1998), S. 699-707 
    ISSN: 1573-5028
    Keywords: actin cytoskeleton ; in situ hybridization ; gene expression ; profilin ; RT-PCR ; tomato pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The actin cytoskeleton plays an important role in the growth of pollen tube. The actin-binding protein profilin could play a role in regulating the organization of the actin filaments. Using the RT-PCR technique, we isolated a cDNA clone (designated LePro1) encoding profilin from pollen grains of tomato (Lycopersicon esculentum Mill. cv. Moneymaker). Sequence analysis of the insert shows 87% similarity to tobacco ntPro2, 78% to timothy grass profilin, 77% to Arabidopsis AthPRF4, 77% to maize ZmPro3, and 73% to birch profilin. Both quantitative PCR and RNA gel blot analyses demonstrated that LePro1 is expressed in a tissue- or cell-type specific manner in the tomato plant. In situ hybridization of 2 µm thick anther sections using a non-radioactive labeling method reveals that LePro1 is expressed only in pollen grains, with undetectable transcription in other parts of the anther or other organs. Phylogenetic analysis of amino acid sequences of 18 plant profilins indicates that two distinct profilin gene classes are present in higher plants. One is pollen-specific, another is constitutive. LePro1 belongs to the former class.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 36 (1998), S. 733-739 
    ISSN: 1573-5028
    Keywords: AGAMOUS ; tomato ; ripening ; calyx ; gene expression ; sepals ; in vitro
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro culture of VFNT Cherry tomato sepals (calyx) at 16–21 °C results in developmental changes that are similar to those that occur in fruit tissue [10]. Sepals become swollen, red, and succulent, produce ethylene, and have increased levels of polygalacturonase RNA. They also produce many flavor volatiles characteristic of ripe tomato fruit and undergo similar changes in sugar content [11]. We examined the expression of the tomato AGAMOUS gene, TAG1, in ripening, in vitro sepal cultures and other tissues from the plant and found that TAG1 RNA accumulates to higher levels than expected from data from other plants. Contrary to reports on the absence of AGAMOUS in sepals, TAG1 RNA levels in green sepals from greenhouse-grown plants is detectable, its concentration increasing with in vitro ripening to levels that were even higher than in red, ripe fruit. Sepals of fruit on transgenic tomato plants that expressed TAG1 ectopically were induced by low temperature to ripen in vivo, producing lycopene and undergoing cell wall softening as is characteristic of pericarpic tissue. We therefore propose that the induction of elevated TAG1 gene expression plays a key role in developmental changes that result in sepal ripening.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 37 (1998), S. 735-748 
    ISSN: 1573-5028
    Keywords: AMP-activated protein kinase ; carbohydrates ; gene expression ; gene family ; HMG-CoA reductase ; intracellular signalling ; isoprenoids ; nitrate reductase ; phosphorylation ; SNF1 ; starch ; sucrose phosphate synthase ; sucrose synthase ; sugar sensing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 37 (1998), S. 1023-1033 
    ISSN: 1573-5028
    Keywords: gene expression ; psbA gene ; truncated psbA messages ; DNA-binding protein ; D1 protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of the psbA genes, which in the cyanobacterium Synechococcus sp. PCC 7942 encode two different forms of the reaction centre D1 protein of photosystem II (D1:1 and D1:2), was studied under different light and temperature conditions. In addition to the mature 1200 nt psbA messages, three shorter mRNA fragments of 220, 320 and 900 nt were also found. All three mRNA fragments could be recognized by using different gene probes from the coding region of the psbAI gene, whereas the corresponding psbAII/III gene probes recognized only the 220 nt mRNA fragment. The 5' 320 nt mRNA fragment from the psbAI gene probably represents a degradation product, since the corresponding 3' 900 nt psbAI mRNA fragment was also detected. By contrast, the 5' 220 nt mRNA fragment of all psbA messages is suggested to be a truncated psbA transcript, since no corresponding 3' fragment was ever found. Inhibition of translation either by a protein synthesis inhibitor or by a shift of cells to lower temperature, increased the number of 1200 nt psbAII/III messages but the number of 5' 220 nt psbAII/III mRNA fragment increased even more dramatically. The first 66 bp after ATG, where the psbAI and psbAII/III genes mostly differ from each other, also appeared important in determining the amount of produced truncated psbA transcripts, as evidenced by the expression of different tac-psbA constructs in the presence of protein synthesis inhibitor. We suggest that both the psbAI and the psbAII/III genes have a latent intragenic termination site and truncated psbA transcripts are produced at high levels under stress conditions when transcription becomes uncoupled from translation.This is to prevent wasting metabolic energy in the production of unused transcripts.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    ISSN: 1573-5028
    Keywords: gene expression ; Candida albicans ; dihydrofolate reductase ; dominant selectable marker ; Nicotiana tabacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new binary vector encoding for Candida albicans dihydrofolate reductase (DFR1) has been constructed and used as a dominant selectable marker for plant transformation. Transgenic tobacco plants with an increased resistance to methotrexate (Mtx) were obtained by co-transformation of tobacco leaf discs with Agrobacterium tumefaciens strains carrying two new binary vectors: pTI20 and pTI18. Co-transformants of Nicotiana tabacum were directly selected for and rooted on medium containing both kanamycin (kan) and Mtx. Leaf discs of transgenic plants were assayed for capacity of regeneration at different Mtx concentrations. Analysis of transcripts was performed on total RNA extracted from two Mtx-resistant plants. The transgenic plants increased resistance to Mtx can be explained by the exceptionally low capacity of Mtx to bind C. albicans dihydrofolate reductase, accountable by the presence of two amino acid residues strategically important in Mtx binding.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    ISSN: 1573-5028
    Keywords: rice ; waxy ; splicing ; gene expression ; intron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rice Waxy gene encodes a granule-bound starch synthase (GBSS) necessary for the synthesis of amylose in endosperm tissue. We have previously shown that a CT microsatellite near the transcriptional start site of the GBSS gene can distinguish 7 alleles that accounted for more than 80% of the variation in apparent amylose content in an extended pedigree of 89 US rice cultivars (Oryza sativa L.). Furthermore, all the cultivars with 18% or less amylose were shown to have the sequence AGTTATA at the putative leader intron 5′ splice site, while all cultivars with a higher proportion of amylose had AGGTATA. Here we demonstrate that this single-base mutation reduces the efficiency of GBSS pre-mRNA processing and results in alternate splicing at three cryptic sites. The predominant 5′ splice site in CT18 low-amylose varieties is 93 bp upstream of the splice site used in intermediate and high amylose varieties and is immediately 5′ to the CT microsatellite that we previously demonstrated to be tightly correlated with amylose content. Use of the leader intron 5′ splice site at either -93 or -1 in conjunction with the predominant 3′ splice site results in formation of a small open reading frame 38 bp upstream of the normal ATG and out of frame with it. This open reading frame is not produced when any of the 5′ leader intron splice sites are used in conjunction with an alternate 3′ splice site five bases further downstream which was observed in all rice varieties tested.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    ISSN: 1573-5028
    Keywords: antisense RNA ; chalcone synthase ; flavonoid ; gene expression ; rooting ; walnut
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Walnut somatic embryos (Juglans nigra × Juglans regia) were transformed with a vector containing a neomycin phosphotransferase II, a β-glucuronidase and an antisense chalcone synthase (chs) gene. This antisense construct included a 400 bp cDNA fragment of a walnut chs gene under the control of the duplicated CaMV-35S promoter. Molecular, biochemical and biological characterizations were performed both on transformed embryos propagated by secondary somatic embryogenesis and on microshoots developed by in vitro culture of embryonic epicotyls from somatic embryos. Thirteen transformed lines with the vector containing the antisense chs gene, one line with only the gus and nptII genes and one untransformed line were maintained in tissue culture. Six of the antisense lines were shown to be flavonoid-deficient. They exhibited a strongly reduced expression of chs genes, very low chalcone synthase activity and no detectable amounts of quercitrin, myricitrin, flavane-3-ols and proanthocyanidins in stems. Rooting tests showed that decreased flavonoid content in stems of antisense chs transformed lines was associated with enhanced adventitious root formation. Free auxin and conjugated auxin contents were determined during the latter phase of the micropropagation, and no variations were detected between control and antisense chs transformed lines. The in vitro plants developed a large basal callus and apical necrosis upon auxinic induction and the transformed lines highly deficient in flavonoids were more sensitive to exogenous application of indolebutyric acid (IBA).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    ISSN: 1573-5028
    Keywords: ribonucleotide reductase ; gene expression ; cell cycle ; S-phase ; tobacco BY2 cell suspension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eukaryotic ribonucleotide reductase (RNR), the enzyme involved in the synthesis of the deoxyribonucleotides, consists of two R1 and R2 subunits whose activities and gene expression are differentially regulated during the cell cycle and are preferentially induced at the G1/S transition. We have isolated three cDNA clones from a tobacco S phase library, two encoding the large R1 subunit, the first cloned in plants, and one encoding the small R2 subunit. From Southern blot hybridization we deduce that RNR2 is encoded by a single-copy gene whereas RNR1 is encoded by a small multigene family. The level of RNR mRNA is cell-cycle regulated showing a maximum in S phase. In mid-S phase, RNR2 transcripts show a higher maximum level than RNR1 transcripts. Analysis of the effects of various cell cycle inhibitors added to freshly subcultured stationary phase cells leads to the conclusion that RNR gene induction at the entry of the cells into the cell cycle takes place in late G1-early S phase. Addition of DNA synthesis-blocking agents to cycling cells synchronized in mid-S phase resulted in an enhancement of RNR transcript level, thus suggesting that RNR gene expression may be linked to the DNA synthesis rate by a feedback-like regulatory mechanism.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    ISSN: 1573-5028
    Keywords: Nicotiana tabacum ; tobacco BY-2 cells ; gene expression ; jasmonic acid ; methyl jasmonate ; ornithine decarboxylase ; polyamine ; nicotine ; SAM synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA of tobacco BY-2 cells corresponding to an mRNA species which was rapidly induced by methyl jasmonate (MeJA) in the presence of cycloheximide (CHX) was found to encode ornithine decarboxylase (ODC). Another cDNA from a MeJA-inducible mRNA encoded S-adenosylmethionine synthase (SAMS). Although these enzymes could be involved in the biosynthesis of polyamines, the level of putrescine, a reaction product of ODC, increased slowly and while the levels of spermidine and spermine did not change following treatment of cells with MeJA. However, N-methylputrescine, which is a precursor of pyrrolidine ring of nicotine, started to increase shortly after MeJA-treatment of cells and the production of nicotine occured thereafter. The levels of mRNA for arginine decarboxylase (ADC), an alternative enzyme for putrescine synthesis, and that for S-adenosylmethionine decarboxylase (SAMDC), required for polyamine synthesis, were not affected by MeJA. In addition to mRNAs for ODC and SAMS, mRNA for putrescine N-methyltransferase (PMT) was also induced by MeJA. Unlike the MeJA-induction of ODC mRNA, MeJA-induction of SAMS and PMT mRNAs were blocked by CHX. The level of ODC mRNA declined after 1 to 4 h following MeJA treatment, while the levels of mRNAs for SAMS and PMT continued to increase. Auxin significantly reduced the MeJA-inducible accumulation of mRNAs for ODC, SAMS and PMT. These results indicate that MeJA sequentially induces expression of a series of genes involved in nicotine biosynthesis by multiple regulatory mechanisms.p〉
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    ISSN: 1573-5028
    Keywords: apoplast ; cDNA cloning ; conifer embryogenesis ; gene expression ; germin-like proteins ; Pinus caribaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germin-like proteins (GLPs) ionically bound to the walls of preglobular somatic embryos of Pinus caribaea Morelet are markers of this early developmental stage. In order to reveal the physiological implications of such markers during early embryo development, we isolated a cDNA clone from somatic embryos predicted to encode a protein with sequence similarity to GLPs. PcGER1 has an open reading frame corresponding to a 220 amino acid polypeptide with a putative N-glycosylation site on Asn-69. The presence of a 24 amino acid putative signal peptide supports the hypothesis of an apoplastic location. The N-terminal 20 amino acid sequence of the predicted mature protein is identical to the amino terminal sequence of GP111, one of the extracellular pine GLPs previously identified. Southern blot hybridizations indicate that PcGER1 is probably unique in the pine genome. Transcripts homologous to PcGER1 are abundant in all embryogenic lines, absent from nonembryogenic lines, and present in quiescent zygotic embryos but not in the female gametophyte, the haploid storage tissue of conifers. Their abundance sharply decreases during germination. Isolation of gf-0.8, a genomic fragment identical to PcGER1 cDNA sequence, confirms that no introns disrupt the coding region as it has been already described for wheat gf-2.8 and gf-3.8 genomic clones. Recombinant PcGER1, produced in Escherichia coli, is recognized by antibodies raised against the GP111 N-terminal nonapeptide and the unglycosylated wheat germin monomer. The implications of GLPs in pine embryogenesis are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    ISSN: 1573-5087
    Keywords: desiccation tolerance ; dehydrin ; gene expression ; glyoxalase ; grass ; Lea ; protease ; Sporobolus stapfianus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to identify genes involved in expression of desiccation tolerance in the foliage of the grass Sporobolus stapfianus, a cDNA library was constructed from desiccated leaf tissue of S. stapfianus. Differential screening resulted in the isolation of a number of clones which detect transcripts whose abundance alters during drought stress and the associated induction of desiccation tolerance. The characteristics of 6 of these cDNA clones are presented here. Transcripts represented by three of the cDNA clones accumulate during drying and following treatment of leaves with abscisic acid (ABA). A fourth cDNA clone detects a transcript which also accumulates following application of ABA but the transcript level fluctuates during drying. The remaining two cDNA clones are not responsive to ABA but transcript levels are present throughout the drying process. Characterisation of these cDNAs has led to the identification of the encoded proteins. Some have similarity to proteins which are known to be involved in the protection of cellular organelles and detoxification processes and they include dehydrin, LEA group 3 and thiol proteases which have been identified in other systems and shown to be induced by water stress. In addition one clone showed similarity to glyoxalase I, an enzyme involved in the removal of toxic byproducts produced during glycolysis, which has been shown to be induced by salt stress in tomato.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    ISSN: 1573-5028
    Keywords: sedoheptulose-1,7-bisphosphatase ; Chlamydomonas reinhardtii ; light regulation ; Calvin cycle ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have studied the light-dependent expression of the Chlamydomonas reinhardtii csbp gene encoding sedoheptulose-1,7-bisphosphatase (SBPase), an enzyme of the pentose-phosphate pathway. Expression studies using light/dark-synchronized cultures revealed that csbp mRNA abundance increases significantly during illumination. We have used a 1.4 kb region upstream of the csbp gene in transcriptional fusions to the homologous arylsulfatase-encoding reporter gene (ars). In transformants carrying the chimeric csbp/ars reporter gene, arylsulfatase activity is detected in the absence of sulfate, a condition under which the endogenous ars gene is repressed. Moreover, ars mRNA accumulation is dramatically stimulated by light, indicating that 1.4 kb of the csbp 5′-untranslated region are sufficient to confer light-dependent expression on the ars reporter gene.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    ISSN: 1573-5028
    Keywords: blue/UV-A-light ; gene expression ; glutamine synthetase ; phytochrome ; tomato aurea mutant ; UV-B-light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photomorphogenetic aurea mutant of tomato severely deficient in spectrophotometrically active phytochromes was used to study the light-regulation of the single-copy nuclear gene encoding plastidic glutamine synthetase (GS-2; EC 6.1.3.2). The de-etiolation of dark-grown aurea mutant seedling cotyledons showed an obligatory dependency on blue light. A limited red light-responsiveness of etiolated aurea cotyledons is, however, retained as seen by the stimulation of both the GS-2 transcript and protein level in the cotyledons of aurea seedlings during growth in red light. The subunits of the octameric GS-2 enzyme were represented by polypeptides with similar electrophoretic mobilities (polypeptides a) in etiolated wild-type or aurea mutant cotyledons. GS-2 proteins with similar apparent molecular masses were also seen in the cotyledons of red light-grown aurea mutant seedlings. In contrast, GS-2 polypeptides with different apparent molecular masses (polypeptides a and b) were detected in the cotyledons of wild-type seedlings grown in red light. This difference indicates that the (post-translational) modification of tomato GS-2 subunit composition is mediated by the photoreceptor phytochrome. The illumination of etiolated wild-type or aurea cotyledons with UV-A- or UV-B-light light resulted in an increase in both the GS-2 transcript and protein level. Following illumination of etiolated wild-type seedlings with UV-A-light, the relative proportion of the GS-2 polypeptides a and b was similar than upon irradiation with blue light but different than after exposure to UV-B- or red light. This result suggests the involvement of a blue/ UV-A-light-specific photoreceptor in the regulation of tomato GS-2 subunit composition.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    ISSN: 1573-5028
    Keywords: aspen ; Populus tremuloides ; xylem ; lignin ; caffeoyl-CoA ; caffeate ; O-methyltransferase ; gene expression ; enzyme activity ; recombinant bacterial overexpression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seasonal expression of caffeoyl-CoA O-methyltransferase (EC 2.1.1.104) was analyzed in aspen developing secondary xylem in parallel with caffeate O-methyltransferase (EC 2.1.1.68). Enzyme activity and mRNA levels for both enzymes peaked in the middle of the growing season. These results strongly suggest that both forms of O-methyltransferase were actively participating in lignin precursor biosynthesis during the growing season. To determine the role of each enzyme form, xylem extracts from two days in the growing season were assayed with four substrates: caffeoyl-CoA, 5-hydroxyferuloyl-CoA, caffeate acid and 5-hydroxyferulic acid. Recombinant forms of caffeoyl-CoA and caffeate O-methyltransferase were also assayed with these substrates. The recombinant enzymes have different substrate specificity with the caffeoyl-CoA O-methyltransferase being essentially specific for CoA ester substrates with a preference for caffeoyl-CoA, while caffeate O-methyltransferase utilized all four substrates with a preference for the free acid forms. We suggest that caffeoyl-CoA O-methyltransferase is likely to be responsible for biosynthesis of lignin precursors in the guaiacyl pathway and may represent a more primitive enzyme form leftover from very early land plant evolution. Caffeate O-methyltransferase is more likely to be responsible for lignin precursor biosynthesis in the syringyl pathway, especially since it can catalyze methylation of 5-hydroxyferuloyl-CoA quite effectively. This latter enzyme form then may be considered a more recently evolved component of the lignin biosynthetic pathways of the evolutionarily advanced plants such as angiosperms.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    ISSN: 1573-5028
    Keywords: binding site selection ; gene expression ; homeobox-leucine zipper genes ; protein-DNA interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report the isolation and characterization of two Arabidopsis homeobox genes highly related to the Athb-8 gene. The full-length cDNAs encode proteins of 841 and 852 amino acids which we have designated Athb-9 and -14, respectively. Athb-8, -9 and -14 are members of a small family of HD-Zip proteins (HD-ZIP III) characterized by a HD-Zip motif confined to the N-terminus of the polypeptide. The spatial organization of the HD-Zip domain of Athb-8, -9 and -14 is different from that of the Athb-1 (a member of the HD-ZIP I family) and Athb-2 (a member of the HD-ZIP II family) HD-Zip domains. DNA binding analysis performed with random-sequence DNA templates showed that the Athb-9 HD-Zip (HD-Zip-9) domain, but not the Athb-9 HD alone, binds to DNA. The HD-Zip-9 domain recognizes a 11 bp pseudopalindromic sequence (GTAAT(G/C)ATTAC), as determined by selecting high-affinity binding sites from random-sequence DNA. Moreover, gel retardation assays demonstrated that the HD-Zip-9 domain binds to DNA as a dimer. These data support the notion that the HD-ZIP III domain interacts with DNA recognition elements in a fashion similar to the HD-ZIP I and II domains.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    ISSN: 1573-5028
    Keywords: gene expression ; nodules ; phosphoribosyl aminoimidazole synthetase ; purine biosynthesis ; N assimilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA (VUpur5) encoding phosphoribosyl aminoimidazole (AIR) synthetase, the fifth enzyme of the de novo purine biosynthesis pathway has been isolated from a cowpea nodule cDNA library. It encodes a 388 amino acid protein with a predicted molecular mass of 40.4 kDa. The deduced amino acid sequence has significant homology with AIR synthetase from other organisms. AIR synthetase is present in both mitochondria and plastids of cowpea nodules [7]. A signal sequence encoded by the VUpur5 cDNA has properties associated with plastid transit sequences but there is no consensus cleavage site as would be expected for a plastid targeted protein. Although the signal sequence does not have the structural features of a mitochondrial targeted protein, it has a mitochondrial cleavage site motif (RX/XS) close to the predicted N-terminus of the mature protein. Southern analysis suggests that AIR synthetase is encoded by a single gene raising questions as to how the product of this gene is targeted to the two organelles. VUpur5 is expressed at much higher levels in nodules compared to other cowpea tissues and the gene is active before nitrogen fixation begins. These results suggest that products of nitrogen fixation do not play a role in the initial induction of gene expression. VUpur5 was expressed in Escherichia coli and the recombinant protein used to raise antibodies. These antibodies recognize two forms of AIR synthetase which differ in molecular size. Both forms are present in mitochondria, although the larger protein is more abundant. Only the smaller protein was detected in plastids.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Springer
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 37 (1998), S. 587-596 
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; gene expression ; leucine-rich repeat ; PCR ; receptor-like kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated three receptor-like kinase cDNAs from an Arabidopsis flower cDNA library by PCR using degenerate oligonucleotide primers for conserved domains of protein kinases. Cloning and sequencing of the full-length cDNAs, designated RKF1 to 3 (receptor-like kinase in flowers), showed that the putative extracellular domain of the RKF1 protein contains 13 tandem repeats of leucine-rich sequences and those of RKF2 and RKF3 have no significant homology with other plant sequences. RNA blot analysis revealed that the RKF1 mRNA is highly expressed in stamens while RKF2 and RKF3 mRNAs are present at low levels in all organs examined. In situ localization experiments indicated that the RKF1 mRNA is detectable in early flower primordia and during stamen development. In addition, when fused to a GUS reporter gene, the RKF1 promoter directed high GUS expression in pollen grains. Recombinant RKF1, produced in Escherichia coli, was found to have kinase activity with serine/threonine specificity in vitro.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    ISSN: 1573-5028
    Keywords: gene expression ; phytohormone ; Lea ; leaf senescence ; senescence-associated gene ; stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of several Arabidopsis thaliana senescence-associated genes (SAGs) in attached and/or detached leaves was compared in response to age, dehydration, darkness, abscisic acid, cytokinin, and ethylene treatments. Most of the SAGs responded to most of the treatments in a similar fashion. Detachment in darkness and ethylene were the strongest inducers of both SAGs and visible yellowing. Detachment in light was also a strong inducer of SAGs, but not of visible yellowing. The other treatments varied more in their effects on individual SAGs. Responses were examined in both older and younger leaves, and generally were much stronger in the older ones. Individual SAGs differed from the norms in different ways, however, suggesting that their gene products play a role in overlapping but not identical circumstances. Some SAGs responded quickly to treatments, which may indicate a direct response. Others responded more slowly, which may indicate an indirect response via treatment-induced senescence. Four new SAGs were isolated as part of this work, one of which shows strong similarity to late embryogenesis-abundant (Lea) genes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    ISSN: 1573-5117
    Keywords: Planarian ; Hox ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seven Hox cluster-related genes (Dthox-A to -G) have been isolated from the freshwater triclad Dugesia (G.) tigrina, their sequence compared to other Hox genes and their expression in intact and regenerating organisms analyzed by whole mount in situ hybridization. Sequence comparison analyses show high similarities of D. tigrina Hox genes to anterior and medial groups of coelomate Hox genes. Expression analyses show very early, synchronous, and overlapping expression of Dthox -A, -E, -G and -F in anterior, posterior and lateral regenerative tissues. At one hour of regeneration all Dthox genes studied showed a neat, clear expression at the wound boundary. Later, as the blastema grows, the expression area expands to more proximal regions covering the blastema and the distal postblastema regions. Blastemas formed by intercalary regeneration also show a synchronous expression of the same Hox genes though the onset of activation is much delayed. The finding that the same set of Hox genes is synchronously activated in anterior, posterior, intercalary and lateral regeneration is in sharp contrast to its well established role in specifying antero-posterior pattern during embryonic development. The implications of these results as regards ancestral versus co-opted roles of Hox genes in development and regeneration are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    ISSN: 1573-0778
    Keywords: CHO ; DHFR ; gene expression ; growth factor ; recombinant protein ; serum-free
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The dihydrofolate reductase-deficient Chinese hamster ovary cell line, DXB11-CHO, commonly used as a host cell for the production of recombinant proteins requires 7.5% serum-supplementation for optimal growth. Regulatory issues surrounding the use of serum in clinical production processes and the direct and indirect costs of using serum in large-scale production and recovery processes have triggered efforts to derive serum-independent host cell lines. We have successfully isolated a serum-free host that we named Veggie- CHO. Veggie-CHO was generated by adapting DXB11-CHO cells to growth in serum-free media in the absence of exogenous growth factors such as Transferrin and Insulin-like growth factor, which we have previously shown to be essential for growth and viability of DXB11- CHO cells. Veggie-CHO cells have been shown to maintain an average doubling time of 22 hr in continuous growth cultures over a period of three months and have retained the dihydrofolate reductase -deficient phenotype of their parental DXB11-CHO cells. These properties and the stability of its serum-free phenotype have allowed the use of Veggie- CHO as host cells for transfection and amplified expression of recombinant proteins. We describe the derivation a serum-free recombinant cell line with an average doubling time of 20 hr and specific productivity of 2.5 Units recombinant Flt-3L protein per 10e6 cells per day.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    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.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    ISSN: 1573-9368
    Keywords: luciferase ; scaffold attachment regions ; heat shock ; blastocyst ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenesis in domestic species, as a research tool and in biotechnological applications, has been limited by the expense of producing transgenic offspring by standard microinjection techniques. A major factor is the inefficiency of maintaining large numbers of recipient females, when a high percentage of these carry nontransgenic fetuses. There are two approaches to reduce this cost, the fusion of transfected fetal fibroblasts with enucleated oocytes, and the screening of microinjected embryos for transgene integration in blastocysts, prior to transfer. Here, we develop a luminescent screening system to select transgenic bovine embryos. A transgene with scaffold attachment regions flanking the murine HSP70.1 promoter linked to firefly luciferase cDNA, was microinjected into pronuclei of in vitro produced zygotes. At the blastocyst stage, the transgene was induced by heat shock (45 °C, 15 min) and 4–6 h later, luciferase expression was analyzed by photon counting imaging. Screened blastocysts were transferred to recipients and day 50 fetuses or calves were analyzed by PCR and Southern blot for transgene integration. When nonluminescent blastocysts were transferred, transgene integration was never observed. Of 13 fetuses derived from luminescent blastocysts, 3 contained integrated transgenes that were functional in all tissues examined. Image analysis of the signal emitted by positive blastocysts revealed that 9 nontransgenic fetuses were obtained from blastocysts that exhibited a localized luminescent signal. On the other hand, 3 of 4 fetuses derived from blastocysts that emitted light over more than 70% of their surface were transgenic. Thus, by selecting luminescent blastocysts on the basis of both signal intensity and distribution, the number of recipient females required to produce transgenic offspring can be greatly reduced. Using this technique it should also be possible to improve the efficiency of transgenesis by microinjection through studies in which vector design and integration conditions are examined at the blastocyst stage.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Springer
    Transgenic research 7 (1998), S. 403-411 
    ISSN: 1573-9368
    Keywords: transgenic organism ; gene expression ; promoter ; plant ; gene regulation ; heterologous system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The regulation of gene expression represents a specific process which has different structural and functional requirements in different groups of organisms. It is thus assumed that regulatory sequences of eucaryotes cannot be recognized in procaryotes. This assumption is of interest for risk assessments of the environmental impact of deliberate release experiments with genetically modified organisms. In order to analyse the extent of heterologous gene expression caused by the transfer of plant-specific regulatory sequences into bacteria, we constructed fusions between plant-specific regulatory sequences and the coding regions of the luxAB genes for the luciferase of the bioluminescent bacterium Vibrio harveyi, transferred the fusions into different bacterial species and measured the luminescence to quantify the expression of the luciferase genes. The regulatory sequences investigated included (a) the 35S promoter of the Cauliflower mosaic virus, (b) the B33 promoter of a class I patatin gene of potatoes, (c) the promoter of the ST-LS1 gene of potatoes and (d) the promoter of the rolC gene of Agrobacterium rhizogenes. We could show that in addition to the 35S promoter, which has already been described as being recognized in Escherichia coli, the sequences containing the B33 and the ST-LS1 promoters are recognized in bacteria. Luciferase gene expression promoted by the sequence with the ST-LS1 promoter could be observed in E. coli, Yersinia enterocolitica and Agrobacterium tumefaciens. Comparison of the luminescence caused by fusions between luxAB and different promoters on the chromosome and on an endogenous plasmid of Y. enterocolitica demonstrated that the level of the heterologous gene expression caused by the fragment with the ST-LS1 promoter was within the range of gene expression levels caused by endogenous promoters of Y. enterocolitica.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...