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  • Articles  (124)
  • gene expression  (124)
  • Springer  (124)
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  • Articles  (124)
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  • Springer  (124)
  • American Chemical Society
  • American Meteorological Society
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  • 1995-1999  (124)
  • 1990-1994
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    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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  • 2
    Electronic Resource
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    Springer
    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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  • 3
    Electronic Resource
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    Springer
    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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  • 4
    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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  • 5
    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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  • 6
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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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  • 7
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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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  • 8
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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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  • 9
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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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  • 10
    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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  • 11
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    Molecular and cellular biochemistry 146 (1995), S. 71-77 
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; 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 was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb of open-reading frame). Regucalcin mRNA was expressed in the kidney cortex, and this expression was clearly increased by a single intraperitoneal administration of calcium chloride solution (5–15 mg Ca/100 g body weight) in rats; this increase was remarkable at 60–120 min after the administration. Thyroparathyroidectomy (TPTX) caused a slight decrease of regucalcin mRNA levels in the kidney cortex. However, the administration of calcium (10 mg/100 g) in TPTX rats produced a clear increase of regucalcin mRNA levels in the kidney cortex. The subcutaneous administration of calcitonin (10–100 MRC mU/100 g) or parathyroid hormone [1–34] (1–10 U/100 g) in TPTX rats which received calcium (10 mg/100 g) administration did not cause an appreciable alteration of regucalcin mRNA levels in the kidney cortex, suggesting that the mRNA expression is not stimulated by calcium-regulating hormones. The administration of trifluoperazine (TFP; 5 mg/100 g), an inhibitor of Ca2+/calmodulin action, completely blocked the expression of regucalcin mRNA stimulated by calcium administration. Now, calcium content in the kidney cortex was significantly elevated by a single intraperitpneal administration of calcium (10 mg/100 g) in rats. The present study clearly demonstrates that the expression of regucalcin mRNA in the kidney cortex is stimulated by calcium administration in rats. This expression may be mediated through Ca2+/calmodulin action in the kidney cortex.
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  • 12
    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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  • 13
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    Molecular and cellular biochemistry 199 (1999), S. 189-200 
    ISSN: 1573-4919
    Keywords: lung ; cancer ; urokinase ; receptor ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The urokinase-type plasminogen activator (uPA) interacts with its receptor (uPAR) to promote proteolysis as well as cell proliferation and migration. These functions contribute to the pathogenesis of neoplastic growth and invasiveness. Expression of uPAR in tumor extracts also inversely correlates with prognosis in many forms of cancer. In this study, we sought to determine if differences in uPAR expression were distinguishable between cultured human lung carcinoma and malignant mesothelioma subtypes. We also sought to determine if, as in malignant mesothelioma cells, uPAR expression is regulated at the posttranscriptional level in cultured malignant lung carcinoma cells. Using 125I-uPA binding and ligand blotting techniques, uPAR was expressed by phenotypically diverse lung carcinoma cell lines, including the H460, H157 and H1395 non-small cell lines and the H146 small cell lung carcinoma line. Increased uPAR expression was also detected in spindle-shaped (M33K) and epithelioid (M9K and MS-1) malignant mesothelioma cells. Selected mediators, including TGF-β, TNF-α, LPS and PMA, uniformly enhanced uPAR expression in each of the tumor cell lines. Steady state uPAR mRNA expression was determined by RNase protection assay and correlated directly with the changes in cell surface uPAR expression. By gel mobility shift and UV-cross linking assays, a uPAR mRNA binding protein (uPAR mRNABp) implicated in the posttranscriptional control of message stability, was identified in each of the cell lines. Expression of uPAR and its message in cultured lung carcinoma and malignant mesothelioma cells is similarly influenced by effectors present in the tumor microenvironment. Regulation of the uPAR message occurs at the posttranscriptional level in cultured small and non-small cell lung carcinoma cells as well as spindle-shaped and fibrous malignant mesothelioma cell lines. Posttranscriptional regulation of uPAR in all these cells involves the interaction of the uPAR mRNABp with uPAR mRNA, which promotes uPAR mRNA destabilization.
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  • 14
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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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  • 15
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; Ca2+-ATPase ; brain microsomes ; aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of calcium-binding protein regucalcin and its effect on the microsomal Ca2+-ATPase activity in rat brain tissues was investigated. The expression of regucalcin mRNA was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) analysis in brain tissues using rat regucalcin-specific primers. Regucalcin concentration in the brain tissues was about 5 × 10-9 M as measured using enzyme-linked immunoadsorbent assay (ELISA), and this level was lowered with increasing age (50 weeks old). The presence of regucalcin (10-9 to 10-7 M) in the enzyme reaction mixture caused a significant decrease in Ca2+-ATPase activity in the brain microsomes of young rats (5 weeks old). Meanwhile, the enzyme activity was not significantly altered by the addition of calmodulin (1 or 50 μg/ml), calbindin (1 or 10 μg/ml), and S-100 A protein (5 or 25 μg/ml), which are other Ca2+-binding proteins in rat brain. The effect of regucalcin to inhibit microsomal Ca2+-ATPase activity was weakened in the brain of rats with increasing age (50 weeks old). The present study demonstrates that regucalcin is expressed in the brain, and that it can uniquely inhibit Ca2+-ATPase activity in the brain microsomes of rats. The findings suggest that regucalcin plays a role in the regulation of microsomal Ca2+-ATPase activity in rat brain tissues.
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  • 16
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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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  • 17
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    Molecular and cellular biochemistry 152 (1995), S. 131-141 
    ISSN: 1573-4919
    Keywords: gene expression ; mRNA ; proto-oncogenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Polyomavirus large T-antigen transgenic mice develop cardiac hypertrophy characterized by an increase in atrial natriuretic factor and β-myosin heavy chain isoform expression. The aim of this study was to examine changes in proto-oncogene expression in hypertrophied hearts from the transgenic mice. Expression of early growth response-1 (Egr-1) mRNA was detected in hearts from all 15 transgenic mice, but was not detectable in 13 control mice. Reverse transcriptase-polymerase chain reaction experiments usingEgr-1-specific primers confirmed the increase inEgr-1 mRNA in enlarged hearts from the transgenic mice. Expression of c-jun,junD and Ha-ras mRNAs was increased in the transgenic hearts 3, 17 and 2.8-fold, respectively. Western blots showed an increase in c-myc, c-jun and ras protein in hypertrophied transgenic hearts. Immunofluorescence analyses confirmed an increase in Egr-1 and c-jun protein in transgenic cardiomyocytes. Proliferating cell nuclear antigen, Ki-ras and HSP 90 mRNAs were decreased 22, 2.7 and 3-fold, respectively in the transgenic hearts. Not altered in most hypertrophied hearts was expression of c-fos, junB, p53, c-neu, c-myc, HSP70, HSP27, TGF-β or IGF-1 mRNAs. Proto-oncogene and growth factor gene expression in hypertrophy induced by PVLT expression is modulated, with some proto-oncogenes increased and others decreased in expression.
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  • 18
    ISSN: 1573-4919
    Keywords: mechanical stretch ; smooth muscle cells ; differential display ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Physical forces induce profound changes in cell phenotype, shape and behavior. These changes can occur in vascular structures as a result of pressure overload and their effects can be seen in atherosclerotic vessels in which smooth muscle cells have undergone hyperplastic and hypertrophic changes. At the molecular level, mechanical stimuli are converted into chemical ones and lead to modulation of gene expression and/or the activation of a new repertoire of genes whose encoded proteins help the cells to adapt to their microenvironment. In this study, we have used a two primer-based mRNA differential display technique to identify candidate mechano-responsive genes in pulmonary artery smooth muscle cells. As compared to the original method described by Liang and Pardee, this technique uses two arbitrary primers instead of an anchored oligo(dt) plus an arbitrary primer in the polymerase chain reaction. The chief advantages of these modifications are an increase in the efficiency of the amplification and in the identification of differentially expressed clones. Using this approach, we compared the pattern of expressed genes in cells cultured under static conditions with those in cells that were mechanically stretched (1 Hz) for 24 h in a well-defined in vitro mechanical system. Three candidate genes that showed reproducible differences were chosen for further characterization and cloning. One clone was under expressed in stretched cells and had a DNA sequence with 90% homology to the human fibronectin gene. Two other clones were highly expressed in stretched cells and had a 92% and a 83% sequence homology with human platelet-activating factor (PAF) receptor and rat insulin-like growth factor-I (IGF-I) genes respectively. Northern blot analysis confirmed low levels of fibronectin mRNA transcripts in stretched cells. In contrast, accumulation of PAF receptor mRNA occurred 30 min after mechanical stretch was initiated whereas IGF-I mRNA levels peaked at 8 h. Both mRNA levels were sustained for up to 24 h of mechanical stretching. These results demonstrate the usefulness of the two primer-based mRNA differential display that enabled us to identify and characterize alterations at the level of gene expression among matrix proteins, G-protein coupled receptors and growth factors, each of whose response to mechanical strain is different. A more complete understanding of these responses will provide further insight into the pathologic processes associated with hypertension and atherosclerosis.
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  • 19
    ISSN: 1573-5028
    Keywords: β-fructofuranosidase ; invertase ; gene expression ; gene structure ; flower buds ; Daucus carota
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three genomic clones (Inv *Dc1, Inv *Dc2 and Inv *Dc3) were isolated by using the cDNA for carrot cell wall β-fructofuranosidase as a probe. The expression patterns of the three genes differed markedly. High levels of Inv *Dc1 transcripts were found in leaves and roots of young carrot, whereas in plants with developing tap roots no transcripts were detected. A high level of mRNA of Inv *Dc1 was also present in suspension-cultured cells. In developing reproductive organs, only low levels of transcripts of Inv *Dc1 were found in flower buds and flowers and none at later stages of development. In contrast, Inv *Dc2 and Inv *Dc3 were not expressed in vegetative plant organs. Invb1 *Dc1 was exclusively and strongly expressed in flower buds, and Inv *Dc3 at a very low level in suspension-cultured cells.
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  • 20
    ISSN: 1573-5028
    Keywords: fruit ; gene expression ; promoter ; ripening ; tomato ; transgenic plant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The 1.4 kb 5′ polygalacturonase (PG) gene-flanking region has previously been demonstrated to direct ripening-specific chloramphenicol acetyl transferase (CAT) expression in transgenic tomato plants. The steady state level of CAT mRNA in these plants was estimated to be less than 1% of the endogenous PG mRNA. Further constructs containing larger PG gene-flanking regions were generated and tested for their ability to direct higher levels of reporter gene expression. A 4.8 kb 5′-flanking region greatly increased levels of ripening-specific reporter gene activity, while a 1.8 kb 3′ region was only shown to have a positive regulatory role in the presence of the extended 5′ region. Transgenic plants containing the CAT gene flanked by both of these regions showed the same temporal pattern of accumulation of CAT and PG mRNA, and steady-state levels of the transgene mRNA were equivalent to 60% of the endogenous PG mRNA on a per gene basis. The proximal 150 bp of the PG promoter gave no detectable CAT activity. However, the distal 3.4 kb of the 4.8 kb 5′ PG promoter was shown to confer high levels of ripening-specific gene expression when placed in either orientation upstream of the 150 bp minimal promoter. The DNA sequence of the 3.4 kb region revealed a 400 bp imperfect reverse repeat, and sequences which showed similarity to functionally significant sequences from the ripening-related, ethylene-regulated tomato E8 and E4 gene promoters. The possible roles of the flanking regions in regulating PG gene expression are discussed.
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  • 21
    ISSN: 1573-5028
    Keywords: acetohydroxyacid synthase ; gene organization ; gene expression ; herbicide resistance ; cotton ; Gossypium hirsutum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The acetohydroxyacid synthase (AHAS) gene family of the cotton AD allotetraploid Gossypium hirsutum has been cloned and characterized. We have identified six different AHAS genes from an analysis of genomic clones and Southern blots of genomic DNA. Four of the six genes are organized as tandem pairs, in which the genes are separated by only 2–3 kb. Conservation of restriction fragment length polymorphisms between G. hirsutum and A-genome and D-genome-containing diploid cottons was sufficient to assign the single genes in clones A5 and A19 to the A and D subgenomes, respectively. Each diploid genome has one tandem pair, but in these cases we could not make specific subgenomic assignments. DNA and deduced amino acid sequences were determined for the A5 and A19 genes, and an AHAS cDNA clone isolated from a leaflibrary. The sequence of the A19 gene matches that of the cDNA clone, while the A5 gene is 97.8% similar. The four genes comprising the tandem pairs are much less similar to the cDNA clone. The deduced amino acid sequences of the mature polypeptides encoded by the A5 and A19 genes are collinear with the housekeeping forms of AHAS from Arabidopsis thaliana, Nicotiana tabacum and Brassica napus. The constitutive expression of A5 and A19 was confirmed with RNase protection assays and northern blots. We conclude that these genes encode the main house-keeping froms of AHAS in G. hirsutum. Among the four AHAS genes comprising the two tandem pairs, at least two are functional. These genes exhibit either low-level constitutive expression (one or both of the ‘downstream’ genes of each pair), or highly specific expression in reproductive tissue (one or both of the ‘upstream’ genes of each pair). The AHAS gene family of G. hirsutum is more complex than that of other plants so far examined.
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  • 22
    ISSN: 1573-5028
    Keywords: Brassica ; phosphate starvation ; gene expression ; β-glucosidase ; mineral nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Differential gene expression at the transcriptional level was examined as an initial step in the investigation of the Pi starvation response of Brassica nigra suspension cells. Total RNA was extracted from 7-day old cells grown in media containing either no Pi, 1.25 mM or 10 mM Pi., In vitro translation was carried out using their respective poly(A)+ RNA isolates and the resultant polypeptides were separated on a high-resolution SDS-PAGE gel. Scanning densitometry identified four polypeptides (ca. 31.7, 32.3, 52.5 and 64.8 kDa) present only in the Pi-starved samples. Screening by differential hybridization was performed on a cDNA library constructed from mRNA isolated from Pi-starved cells. Probes prepared from mRNA from Pi-deficient and Pi-sufficient cells identified a number of clones representing mRNA species that were preferentially transcribed under Pi deficiency. These phosphate starvation-responsive (psr) clones were placed into eleven groups as determined by cross-hybridization. Northern blots showed that the corresponding genes are inducible in both mild and severe Pi starvation conditions. Preliminary sequencing identified one of the clones as being homologous to β-glucosidases from several plant species. The possible role of β-glucosidase during Pi starvation and the identities of the other psr genes are discussed.
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  • 23
    ISSN: 1573-5028
    Keywords: linked gene ; gene expression ; peroxidase ; Populus kitakamiensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genomic library was prepared from Populus kitakamiensis and screened with the cDNA for an anionic peroxidase from P. kitakamiensis. One genomic clone was isolated that contained two tandemly oriented genes for anionic peroxidases, prxA3a and prxA4a. Both genes consisted of four exons and three introns; the introns had consensus nucleotides, namely, GT and AG, at their 5′ and 3′ ends, respectively. The prxA3a and prxA4a genes encoded 347 and 343 amino acid residues, respectively, including putative signal sequences at the amino-termini. Putative promoters and polyadenylation signals were found in the flanking regions of both genes. The sequence of the coding region of prxA3a was completely identical to that of the cDNA clone pA3, whereas the sequence of the coding region of prxA4a was only 73% identical to that of the cDNA clone pA3. Northern blot analysis showed that the patterns of expression of the mRNAs that corresponded to prxA3a and prxA4a differed in stems of P. kitakamiensis.
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  • 24
    ISSN: 1573-5028
    Keywords: anthocyanin ; Compositae ; corolla ; dfr ; flower development ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the ornamental cut flower plant Gerbera hybrida the spatial distribution of regulatory molecules characteristic of differentiation of the composite inflorescence is visualized as the various patterns of anthocyanin pigmentation of different varieties. In order to identify genes that the plant can regulate according to these anatomical patterns, we have analysed gene expression affecting two enzymatic steps, chalcone synthase (CHS) and dihydroflavonol-4-reductase (DFR), in five gerbera varieties with spatially restricted anthocyanin pigmentation patterns. The dfr expression profiles vary at the levels of floral organ, flower type and region within corolla during inflorescence development according to the anthocyanin pigmentation of the cultivars. In contrast, chs expression, although regulated in a tissue-specific manner during inflorescence development, varies only occasionally. The variation in the dfr expression profiles between the varieties reveals spatially specific gene regulation that senses the differentiation events characteristic of the composite inflorescence.
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  • 25
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    Plant molecular biology 27 (1995), S. 441-456 
    ISSN: 1573-5028
    Keywords: HSP70 ; HSC70 ; seed development ; imbibition ; chaperone ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eukaryotes express several cytoplasmic HSP70 genes, and their encoded proteins participate in diverse cellular processes. Three cDNAs encoding highly expressed cytoplasmic HSP70 homologues from Pisum sativum were cloned and characterized. They were designated PsHSP71.2, PsHSC71.0, and PsHSP70b. These HSP70 genes have different expression profiles in leaves: PsHSP71.2 is observed only in response to heat stress, PsHSC71.0 is present constitutively, and PsHSP70b is weakly constitutively expressed, but induced strongly in response to heat stress. In addition to being heat induced, the PsHSP71.2 mRNA is also expressed in zygotic, but not maternal organs of developing pea seeds, while PsHSC71.0 and PsHSP70b mRNAs are present in maternal and zygotic organs throughout seed development. Immunoblot analysis of parallel protein samples detects a 70 kDa polypeptide in all samples, and a 72 kDa polypeptide that corresponds to the PsHSP71.2 gene product is observed in cotyledons beginning at mid-maturation and in axes beginning between late maturation and desiccation. This polypeptide is not detected in the seed coat. The 72 kDa polypeptide remains abundant in both cotyledons and axes through germination, but declines substantially between 48 and 72 h after the onset of imbibition. Differential control of HSP70 expression during heat stress, seed maturation, and germination is consistent with the hypothesis that there are functional distinctions between cytoplasmic HSP70s.
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  • 26
    ISSN: 1573-5028
    Keywords: Cucumis sativus ; gene expression ; glyoxylate cycle ; glyoxysome ; isocitrate lyase ; seed germination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cucumber (Cucumis sativus L.) genome contains only a single gene encoding the glyoxylate cycle enzyme isocitrate lyase (ICL). The cucumber icl gene has been isolated and sequenced, revealing only two small introns. The predicted amino acid sequence is more than 85% identical to ICL from other higher plants, and contains the C-terminal tripeptide Ser-Arg-Met which resembles a peroxisomal targeting sequence. The icl gene is coordinately expressed with the malate synthase (ms) gene after seed germination in both the light and the dark, suggesting that these genes may contain similar DNA elements regulating transcription. The start of transcription of the icl gene was determined and the DNA sequences upstream compared with the region of the ms gene promoter known to regulate transcription. This comparison revealed a highly conserved DNA sequence at similar positions in each gene.
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  • 27
    ISSN: 1573-5028
    Keywords: Alfalfa ; cell division cycle ; chromosomal location ; cyclin ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyclins in association with the protein kinase p34cdc2and related cyclin-dependent protein kinases (cdks) are key regulatory elements in controlling the cell division cycle. Here, we describe the identification and characterization of a full-length cDNA clone of alfalfa mitotic cyclin, termed CycIIIMs. Computer analysis of known plant cyclin gene sequences revealed that this cyclin belongs to the same structural group as the other known partial alfalfa cyclin sequences. Genetic segregation analysis based on DNA-DNA hybridization data showed that the CycIIIMs gene(s) locates in a single chromosomal region on linkage group 5 of the alfalfa genetic map between RFLP markers UO89A and CG13. The assignment of this cyclin to the mitotic cyclin class was based on its cDNA-derived sequence and its differential expression during G2/M cell cycle phase transition of a partially synchronized alfalfa cell culture. Sequence analysis indicated common motifs with both the A- and B-types of mitotic cyclins similarly to the newly described B3-type of animal cyclins.
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  • 28
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    Plant molecular biology 29 (1995), S. 647-662 
    ISSN: 1573-5028
    Keywords: gene expression ; peroxidase ; powdery mildew ; splicing ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A PCR-based screening approach was used to isolate genomic clones from wheat encoding peroxidase isozymes. Three complete genes (pox1, pox2 and pox4) and one truncated gene (pox3) were characterized. The nucleotide sequences predicted mature proteins of 31 kDa, in which all the highly conserved motifs of secreted plant peroxidases were preserved. The coding regions showed 73–83% DNA sequence identity, with the highest level of similarity noted for the tandemly oriented pox2 and pox3. Expression of respective pox genes in various tissues of wheat was assessed by the RT-PCR technique, which showed that all four genes are active. The primary pox1 mRNA was spliced to remove three introns, whereas processing of the other pox transcripts involved only two intervening sequences. Splicing occurred at consensus GU/AG splice sites except for the first introns of pox1, pox2 and pox4 transcripts, where processing took place at unusual GC donor sites. The RNA analysis suggested that the pox1, pox2 and pox4 genes are predominantly expressed in roots. Lower levels of expression were found for pox4 and pox3 in leaves. Infection of wheat by the powdery mildew fungus selectively induced expression of pox2 in leaves.
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  • 29
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    Plant molecular biology 29 (1995), S. 1211-1221 
    ISSN: 1573-5028
    Keywords: ferredoxin ; Citrus ; ethylene ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sequence and expression of mRNA homologous to a cDNA encoding a non-photosynthetic ferredoxin (Fd1) from Citrus fruit was investigated. The non-photosynthetic nature of this ferredoxin was deduced from: (1) amino acid sequence alignments showing better scores with non-photosynthetic than with photosynthetic ferredoxins, (2) higher expression in tissues containing plastids other than chloroplast such as petals, young fruits, roots and peel of fully coloured fruits, and (3) the absence of light-dark regulation characteristic of photosynthetic ferredoxins. In a phylogenetic tree constructed with higher-plant ferredoxins, Citrus fruit ferredoxin clustered together with root ferredoxins and separated from the photosynthetic ferredoxins. Non photosynthetic (root and fruit) ferredoxins, but not the photosynthetic ferredoxins, have their closest homologs in cyanobacteria. Analysis of ferredoxin genomic organization suggested that non-photosynthetic ferredoxins exist in Citrus as a small gene family. Expression of Fd1 is developmentally regulated during flower opening and fruit maturation, both processes may be mediated by ethylene in Citrus. Exogenous ethylene application also induced the expression of Fd1 both in flavedo and leaves. The induction of non-photosynthetic ferredoxins could be related with the demand for reducing power in non-green, but biosynthetically active, tissues.
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  • 30
    ISSN: 1573-4978
    Keywords: MAR ; SCS ; insulation ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The flanking sequences of several genes have been shown to direct a position independent expression of transgenes. Attempts to completely identify the insulating sequences have failed so far. Some of these sequences contain a matrix attached region (MAR) located in the flanking part of the genes. This article will show that the MARs in cultured cells located in the 3' OH region of the human apolipoprotein B100 (Apo B100) and within the SV40 genome were unable to stimulate and insulate transgene expression directed by the promoters from a rabbit whey acidic protein (WAP) gene or from human cytomegalovirus (hCMV) early genes. In transgenic mice, the MAR from the Apo B100 and SV40 genes did not enhance the expression of a transgene containing the rabbit whey acid protein (WAP) promotor, the late gene SV40 intron (VP1 intron), the bovine growth hormone (bGH) cDNA and the SV40 late gene terminator. This construct was even toxic for embryos. Similarly, the specialized chromatin structure (SCS) from the Drosophila 87A7 HSP70 gene reduced chloramphenicol acetyl transferase (CAT) activity when added between a cytomegalovirus (CMV) enhancer and a Herpes simplex thymidine kinase (TK) gene promoter. This inhibitory action was almost complete when a second SCS sequence was added before the CMV enhancer. Sequences from the firefly luciferase and from the human gene cathepsin D cDNA used as control unexpectedly showed a similar inhibitory effect when added to the CMVTKCAT construct instead of SCS. When added before the CMV enhancer and after the transcription terminator in the CMVTKCAT construct, the SCS sequence was unable to insulate the integrated gene as seen by the fact that the level of CAT in cell extracts were by no means correlated with the number of copies in individual clones. From these data, it is concluded that i) a MAR containing the canonical AT rich sequences does not amplify the expression of all gene constructs ii) AT rich MAR sequences do not have per se an insulating effect iii) Drosophila SCS from the 87A7 HSP70 gene has no insulating effect in all gene constructs (at least in mammalian cells) iv) and the addition of a DNA fragment between an enhancer and a promoter in a gene construct cannot be used as a reliable test to evaluate its insulating property.
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  • 31
    ISSN: 1573-5028
    Keywords: gene expression ; embryo sac ; ovule ; Petunia hybrida ; protein ; kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mitogen activated protein (MAP) kinase pathway of eukaryotes is stimulated by many growth factors and is required for the integration of multiple cellular signals. In order to study the function of MAP kinases during plant ovule development we have synthesized a Petunia hybrida ovule-specific cDNA library and screened for MAP protein kinase-related sequences using a DNA probe obtained by PCR. A full-length cDNA clone was identified (PMEK for Petunia hybrida MAP/ERK-related protein kinase) and shown to encode a protein related to the family of MAP/ERK protein kinases. Southern blot analysis showed that PMEK is a member of a small multigene family in P. hybrida. The cDNA codes for a protein (PMEK1) of 44.4 kDa with an overall sequence identity of 44% to the products of the mammalian ERK/MAP kinase gene, and the budding yeast KSS1 and FUS3 genes. PMEK1 displays 96 and 80% identity respectively with the tobacco NTF3 and Arabidopsis ATMPK1 kinases, and only 50% to the more distantly related plant MAP kinase MsERK1 from alfalfa. The two phosphorylation sites found in the loop between subdomain VII and VIII in all the other MAP kinases are also present in PMEK1. RNA gel blot and RT-PCR analyses demonstrated that PMEK1 is expressed in vegetative organs and preferentially accumulated in female reproductive organs of P. hybrida. In situ hybridization experiments showed that in the reproductive organs PMEK1 is expressed only in the ovary and not in the stamen.
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  • 32
    ISSN: 1573-5028
    Keywords: ADP-glucose pyrophosphorylase (small and large subunit) ; DNA sequence ; gene expression ; starch synthesis ; sugar beet (Beta vulgaris L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cDNA cloning of a small and a large subunit of ADP-glucose pyrophosphorylase (AGPase) from sugar beet is reported. The deduced amino acid sequences are highly homologous to previously identified AGPase polypeptides from other plant species. Both subunits are encoded by low copy genes. When RNA gel blot experiments were performed, strongest expression was detected in sink and source leaves of greenhouse-grown sugar beet plants. A lower expression was found in other tissues tested, i.e. in the hypocotyl, the tap root and roots. In these tissues, slightly higher transcript levels were found for the small subunit gene than for the large subunit gene.
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  • 33
    ISSN: 1573-5028
    Keywords: glycine betaine ; betaine aldehyde dehydrogenase ; osmotic stress ; gene expression ; plant hormone ; abscisic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When subjected to salt stress or drought, some vascular plants such as barley respond with an increased accumulation of the osmoprotectant glycine betaine (betaine), being the last step of betaine synthesis catalyzed by betaine aldehyde dehydrogenase (BADH). We report here cloning and characterization of BADH cDNA from barley, a monocot, and the expression pattern of a BADH transcript. An open reading frame of 1515 bp encoded a protein which showed high homology to BADH enzymes present in other plants (spinach and sugar-beet) and in Escherichia coli. Transgenic tobacco plants harboring the clone expressed high levels of both BADH protein and its enzymatic activity. Northern blot analyses indicated that BADH mRNA levels increased almost 8-fold and 2-fold, respectively, in leaves and roots of barley plants grown in high-salt conditions, and that these levels decreased upon release of the stress, whereas they did not decrease under continuous salt stress. BADH transcripts also accumulate in response to water stress or drought, indicating a common response of the plant to osmotic changes that affect its water status. The addition of abscisic acid (ABA) to plants during growth also increased the levels of BADH transcripts dramatically, although the response was delayed when compared to that found for salt-stressed plants. Removal of plant roots before transferring the plants to high-salt conditions reduced only slightly the accumulation of BADH transcripts in the leaves.
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  • 34
    ISSN: 1573-5028
    Keywords: chloroplasts ; gene expression ; heat bleaching ; photosynthesis ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A shift in the ratio of chlorophyll (Chl) a and Chl b is an early indicator of heat bleaching in Euglena gracilis. This observation prompted us to consider whether or not changes in steady-state levels of chloroplast transcripts and in transcriptional activity could limit the synthesis of Chl a-binding proteins in bleaching plastids. We found that the mature transcripts for CP47 and CP43, the Chl a-binding apoproteins of the proximal antenna of photosystem II, decline sharply very early during bleaching. Our study also shows that transcription of psbB and psbC, the chloroplast genes encoding CP47 and CP43, remains essentially unchanged during the same interval. We conclude that posttranscriptional events, such as mRNA stability, could play a major role in initiating an irreversible loss of chloroplast function in Euglena at a moderately elevated temperature. Lack of these transcripts would eventually impair the assembly of photosystem II in thylakoids.
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  • 35
    ISSN: 1573-5028
    Keywords: gene expression ; gene family ; higher plants ; Hordeum vulgare ; metabolic regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have amplified and cloned DNA sequences derived from a gene encoding a SNF1 (sucrose-non-fermenting 1)-related protein kinase which differs from that previously reported from barley. Northern blot and polymerase chain reaction (PCR) analysis of RNA populations, using specific probes and oligonucleotide primers, indicated that the two SNF1-related genes are differentially regulated. One is expressed in all tissues, whereas the other is expressed at high levels in the seed endosperm and aleurone, but at levels undetectable by northern blot analysis in other tissues. Comparisons with other plant SNF1-related protein kinase genes suggest that the form which is expressed at greatly enhanced levels in the seed is less similar to the other plant homologues which have been reported and may be unique to cereals.
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  • 36
    ISSN: 1573-5028
    Keywords: gene expression ; light regulation ; nitrate reductase ; phytochrome ; signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have explored the possible involvement of the phosphoinositide (PI) cycle and protein kinase C (PKC) in the phytochrome (Pfr)-mediated light signal transduction pathway using nitrate reductase (NR) and phytochrome-I (PhyI) genes as model systems. We have shown earlier that phorbol myristate acetate (PMA) completely replaces the red light effect in stimulating nitrate reductase activity and transcript levels in maize. In this paper, we present detailed evidence to show that PMA mimics the red light effect and follows similar kinetics to enhance NR steady-state transcript accumulation in a nitrate-dependent manner. We also show that PMA inhibits phyI steady-state transcript accumulation in a manner similar to red light, indicating that a PKC-type enzyme(s) may be involved in mediating the light effect in both cases. Serotonin or 5-hydroxytryptamine (5-HT), a stimulator of PI turnover, was also found to mimic the red light effect in enhancing NR transcript levels and inhibiting phyI transcript accumulation, indicating the role of the PI cycle in generating second messengers for regulating the two genes. These results indicate that phytochrome-mediated light regulation of NR and phyI gene expression may involve certain common steps in the signal transduction pathway such as the PI cycle and protein phosphorylation by a PKC-type enzyme.
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  • 37
    ISSN: 1573-5028
    Keywords: auxin ; DNA binding factor ; gene expression ; glutathione S-transferase ; Nicotiana tabacum ; signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have analysed the promoter regions of two closely related auxin-regulated glutathione S-transferase genes. All active deletion constructs tested showed expression of the reporter gene β-glucuronidase (gusA) in root tips of young seedlings and newly developing lateral roots. Auxin treatment greatly enhanced the level of expression. The Nt103-1 promoter region −370/−276 was found to be necessary, at least as a quantitative element to confer auxin-responsiveness to a reporter gene, and sequences responsible for the auxin-responsiveness must be located downstream of −370. The region −651/−370 contains sequence information necessary for uninduced expression. The Nt103-35 promoter manifested its auxin-responsiveness within the −504/−310 region. Electrophoretic mobility shift analysis, using nuclear extracts from tobacco leaves and suspension cells, identified a factor binding to a sequence (ap103, TGAGTCT) at position −560 of the Nt103-1 promoter, which shows homology to the mammalian AP-1 site. A second factor was found to bind a sequence (as103, ATAGCTAAGTGCTTACG) with homology to the CaMV 35S promoter as-1 element. The as103 element is present in both promoters and positioned around −360, so within the region determined to be indispensable for the response to auxin. A third factor was found binding to the −276/−190 region of both promoters. Combined, these data point to the relevance of a 90 bp region for auxin-induced activity of both tobacco genes. The ASF-1 like factor binding to the as103 element within this region might be involved in mediating the auxin response.
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  • 38
    ISSN: 1573-5028
    Keywords: differential screening ; gene expression ; Lycopersicon esculentum ; rin ; ripening inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A tomato fruit cDNA library was differentially screened to identify mRNAs present at higher levels in fruit of the tomato ripening mutant rin (ripening inhibitor). Complete sequencing of a unique clone ERT D1 revealed an open reading frame with homology to several glutamate decarboxylases. The deduced polypeptide sequence has 80% overall amino acid sequence similarity to a Petunia hybrida glutamate decarboxylase (petGAD) which carries a calmodulin-binding site at its carboxyl terminus and ERT D1 appears to have a similar domain. ERT D1 mRNA levels peaked at the first visible sign of fruit colour change during normal tomato ripening and then declined, whereas in fruit of the ripening impaired mutant, rin, accumulation of this mRNA continued until at least 14 days after the onset of ripening. This mRNA was present at much lower levels in other tissues, such as leaves, roots and stem, and was not increased by wounding. Possible roles for GAD, and its product γ-aminobutyric acid (GABA) in fruit, are discussed.
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  • 39
    ISSN: 1573-5028
    Keywords: carotenoids ; cleavage site ; gene expression ; melon ; phytoene synthase ; ripening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone (MEL5), encoding a protein homologous to phytoene synthase (PSY), has been isolated from a climacteric melon fruit cDNA library, using the tomato cDNA clone TOM5 [34] as a heterologous probe. MEL5 hybridised to a transcript of 1.65 kb which suggested that the 1.36 kb clone, isolated originally, was not full-length. The missing 5′ end was isolated by a reverse transcriptase-polymerase chain reaction (RT-PCR)-based method. This enabled the full sequence of the protein to be deduced and the cleavage site of the transit peptide for chromoplast import to be predicted. Northern analysis of RNA extracted from fruit samples of different ripening stages as well as from roots, leaves and flower petals was used to examine the expression pattern of the corresponding mRNA. The transcript corresponding to MEL5 is present at low quantities in unripe (green) fruit, reaches its highest levels when the fruit turns from green to orange and persists at lower levels during later ripening stages. A similar transcript was also detected in flower petals and in trace amounts in leaves and roots. Genomic Southern analysis indicates that the clone is homologous to a low-copy-number gene family. Sequence analysis showed a high degree of conservation among plant PSYs.
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  • 40
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    Plant molecular biology 29 (1995), S. 11-23 
    ISSN: 1573-5028
    Keywords: drought ; flooding ; freezing tolerance ; gene expression ; salt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six cDNAs representing unique cold-induced sequences have been cloned from the hardy citrus relative Poncirus trifoliata. Among these, pBCORc115 and pBCORc119 were found to belong to the same gene family. Sequencing data indicated that pBCORc115 and pBCORc119 each contained an open reading frame, coding for a 19.8 kDa protein (COR19) and a smaller 11.4 kDa protein (COR11) respectively. Inspection of the deduced amino acid sequences revealed three large repeats in COR19, but only one was present in the COR11. Two elements: a Q-clustered tract and a K-rich motif were identified in each repeat. The K-rich motifs were similar to those of cotton D-11 and Group 2 LEA proteins. A Serine-cluster, a common feature in many Group 2 LEA-like proteins, was also found in these proteins, but it was in an unusual position at the carboxy-terminus. A bipartite motif of basic residues, similar to known nuclear targeting sequences, was also present in COR19 and COR11, suggesting that members of this protein family may have a nuclear targeting function. The expression of COR19 mRNA in response to cold acclimation, drought, flooding, and salinization was examined. COR19 expression in leaf tissue was induced in response to cold acclimation, but repressed during drought and flooding stress.
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  • 41
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    Plant molecular biology 29 (1995), S. 367-377 
    ISSN: 1573-5028
    Keywords: Avena sativa ; gene expression ; PHYA ; light regulation ; mRNA degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gene-preferential oligonucleotide probes were used to determined the relative abundance and half-lives of distinct oat phytochrome A (PHYA) mRNAs. Oat PHYA mRNAs are highly conserved in the 5′-untranslated region and the coding region, but the 3′-untranslated region has an overall lower sequence conservation and was the source of gene-preferential probes. PHYA3 mRNA was estimated to be ca. 61% of the oat PHYA mRNA pool present in poly(A)+ RNA from dark-grown seedlings. The half-lives for PHYA3 and PHYA4 mRNAs were both estimated to be ca. 30 min, and a similar short half-life was estimated for the average PHYA mRNA. Sequence comparisons of PHYA mRNAs from four grass species identified conserved sequences within the 5′- and 3′-untranslated regions that might be important for PHYA mRNA degradation.
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  • 42
    ISSN: 1573-5028
    Keywords: Ascorbate peroxidase ; Arabidopsis thaliana ; gene expression ; guaiacol peroxidase ; ozone ; sulfur dioxide
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    Notes: Abstract The effects of ozone or sulfur dioxide on antioxidant enzymes were investigated in Arabidopsis thaliana. Plants were fumigated with 0.1–0.15 ppm ozone or sulfur dioxide up to about 1 week in an environment-controlled chamber. Both pollutants increased the activities of ascorbate peroxidase and guaiacol per-oxidase in leaves, but had little effect on the activities of superoxide dismutase, catalase, monodehydroascorbate reductase, dehydroascorbate reductase or glutathione reductase. Ozone was more effective than sulfur dioxide in increasing the activities of the peroxidases. Ascorbate peroxidase activity increased 1.8-fold without a lag period during fumigation with 0.1 ppm ozone, while guaiacol peroxidase activity increased 4.4-fold with a 1-day lag. Expression of the APX1 gene encoding cytosolic ascorbate peroxidase was further investigated. Its protein levels in leaves exposed to 0.1 ppm ozone for 4 or 8 days were 1.5-fold higher than in controls. Both ozone and sulfur dioxide elevated APX1 mRNA levels in leaves at 4 and 7 days, whereas at 1 day only ozone was effective. The induction of APX1 mRNA levels by ozone (3.4- to 4.1-fold) was more prominent than that by sulfur dioxide (1.6-to 2.6-fold). The APX1 mRNA level increased by day and decreased by night. Exposure of plants to 0.1 ppm ozone enhanced the APX1 mRNA level within 3 h, which showed a diurnal rhythm similar to that of the control. These results demonstrate that near-ambient concentrations of ozone as well as similar concentrations of sulfur dioxide can induce APX1 gene expression in A. thaliana.
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  • 43
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    Plant molecular biology 29 (1995), S. 823-831 
    ISSN: 1573-5028
    Keywords: afterripening ; aldose reductase ; Avena fatua ; gene expression ; LEA ; seed dormancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To analyze the patterns of gene expression associated with seed dormancy in wild oat (Avena fatua), we have isolated cDNA clones corresponding to genes that are differentially expressed in dormant and afterripened line M73 embryos. Gene transcripts of these clones were maintained in embryos of imbibed dormant caryopses, but declined rapidly in afterripened embryos after imbibition. GA3 treatment of dormant caryopses, which breaks dormancy, could lower the transcript levels in dormant embryos. When the germination of afterripened caryopses was inhibited by high temperature (35 °C), the decline in abundance of the transcripts in afterripened embryos was arrested. These genes were expressed to various degrees in water-stressed, but not in unstressed, 7-day-old seedlings. The expression of the genes was also ABA-inducible in afterripened embryos. The expression patterns in non-dormant line SH430 wild oat were similar to those of afterripened M73. DNA sequence analyses indicated that some of the cDNA clones encode LEA (late embryogenesis-abundant) proteins and aldose reductase. The significance of the expression of these genes in maintaining seed dormancy or longevity is discussed.
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  • 44
    ISSN: 1573-5028
    Keywords: carbon catabolite repression ; cDNA ; gene expression ; stress-induced genes ; glucose-starvation ; Zea mays
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    Notes: Abstract In order to isolate glucose-starvation-related cDNAs in maize (Zea mays L.) root tips, a cDNA library was constructed with poly(A)+ mRNA from 24 h starved root tips. After differential screening of the library, we isolated six different cDNAs (named pZSS2 and pZSS7) which were expressed during glucose starvation. Time course analysis revealed that maximum expression of five of these genes occurs 30 h after the onset of the starvation treatment. On the contrary, the expression of mRNAs corresponding to pZSS4 was maximal at an early stage of starvation and then dramatically decreased. The expression of this gene did not seem to be specific for glucose starvation. The pattern of induction of the genes corresponding to pZSS2, pZSS3, pZSS5, pZSS6 and pZSS7 revealed that non-metabolizable sugars such as L-glucose and mannitol induce mRNA transcription similarly to glucose starvation. When D-glucose or any other metabolizable sugar was supplied, the level of transcripts was reduced. Nucleotide sequence analyses of the six cDNAs allowed identification of five of them by comparison with sequence data bases. The protein encoded by clone pZSS2 is analogous to a wound-induced protein from barley. Clones pZSS4 to pZSS7 encode, respectively, a transmembrane protein, a cysteine protease, a metallothionein-like protein and a chymotrypsin/subtilisin-like protease inhibitor. Clone pZSS3 shares no significant homology with any known sequence.
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  • 45
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    Plant molecular biology 28 (1995), S. 647-656 
    ISSN: 1573-5028
    Keywords: abscission ; gene expression ; polygalacturonase ; ethylene ; auxin
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    Topics: Biology
    Notes: Abstract Abscission, organ separation, is accompanied by cell wall breakdown in separation layer cells. In tomato (Lycopersicon esculentum), ethylene-induced abscission is correlated with an increase in polygalacturonase (PG) and endo-β-1,4-D-glucanase (cellulase) activity. We have identified a putative, abscission-specific cDNA clone for PG, pTAPG1. The TAPG1 cDNA has 43% identity at the amino acid level with the tomato fruit PG. Genomic blot analysis suggests that the gene for TAPG1 is a member of a small subfamily of PG genes that is distinct from the tomato fruit PG. The TAPG1 cDNA hybridizes to mRNA expressed during the course of ethylene-induced leaf and flower abscission. A high level of PG transcript accumulation coincides with the occurrence of abscission. Auxin, an abscission inhibitor, and silver thiosulfate, an ethylene action inhibitor, suppressed accumulation of mRNA in leaf abscission zones complementary to the TAPG1 cDNA. Expression of TAPG1 transcripts is several-fold higher in flower abscission zones than in leaf abscission zones. The identification of cDNAs that encode abscission-specific PG provide and additional tool to study the regulation of abscission and cell wall dissolution in separation layer cells.
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  • 46
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    Plant molecular biology 28 (1995), S. 667-676 
    ISSN: 1573-5028
    Keywords: gene expression ; promoter ; glyceraldehyde-3-phosphate dehydrogenase ; Zea mays
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    Topics: Biology
    Notes: Abstract Transient expression experiments show that the maize GapA1 promoter exhibits a requirement for sequences contained within intron 1 and surrounding exon border regions for expression in maize Black Mexican Sweet cells. Maize GapA1-promoter constructs lacking intron 1 are inactive. Intron 1 and its exon border sequences, when reintroduced into constructs lacking introns, restore gene activity whereas intron 2 and its exon borders to not. The minimal promoter so defined encompasses roughly 250 bp upstream of the in vivo transcription start and appears also to include intron 1. An octameric sequence was identified in intron 1 of maize GapA1 which is similar to sequence motifs found in other maize introns known to increase transient expression. Partial restoration of gene expression in GapA1 constructs lacking intron 1 was achieved through insertion of the identified octameric sequence.
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  • 47
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    Plant molecular biology 28 (1995), S. 739-750 
    ISSN: 1573-5028
    Keywords: alcohol dehydrogenase ; fermentation ; gene expression ; pollen ; pyruvate decarboxylase ; respiration ; tobacco
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    Topics: Biology
    Notes: Abstract We characterized the genes coding for the two dedicated enzymes of ethanolic fermentation, alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC), and show that they are functional in pollen. Two PDC-encoding genes were isolated, which displayed reciprocal regulation: PDC1 was anaerobically induced in leaves, whereas PDC2 mRNA was absent in leaves, but constitutively present in pollen. A flux through the ethanolic fermentation pathway could be measured in pollen under all tested environmental and developmental conditions. Surprisingly, the major factor influencing the rate of ethanol production was not oxygen availability, but the composition of the incubation medium. Under optimal conditions for pollen tube growth, approximately two-thirds of the carbon consumed was fermented, and ethanol accumulated into the surrounding medium to a concentration exceeding 100 mM.
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  • 48
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    Plant molecular biology 28 (1995), S. 811-820 
    ISSN: 1573-5028
    Keywords: β-oxidation ; gene expression ; fruit ripening ; Mangifera indica ; peroxisomes ; thiolase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fruit ripening is a complex, developmentally regulated process. A series of genes have been isolated from various ripening fruits encoding enzymes mainly involved in ethylene and cell wall metabolism. In order to aid our understanding of the molecular basis of this process in a tropical fruit, a cDNA library was prepared from ripe mango (Mangifera indica L. cv. Manila). By differential screening with RNA poly(A)+ from unripe and ripe mesocarp a number of cDNAs expressing only in ripe fruit have been isolated. This paper reports the characterization of one such cDNA (pTHMF 1) from M. indica which codes for a protein highly homologous to cucumber, rat and human peroxisomal thiolase (EC 2.3.1.16), the catalyst for the last step in the β-oxidation pathway. The cDNA for the peroxisomal mango thiolase is 1305 bp in length and codes for a protein of 432 amino acids with a predicted molecular mass of 45 532 Da. Mango thiolase is highly homologous to cucumber thiolase (80%), the only other plant thiolase whose cloning has been reported, and to rat and human thiolases (55% and 55% respectively). It is shown by northern analysis that during fruit ripening THMF 1 is up-regulated. A similar pattern of expression was detected in tomato fruit. Wounding and pathogen infection do not appear to affect THMF 1 expression. The possible involvement of thiolase in fatty acid metabolism during fruit ripening will be discussed. To our knowledge this is the first report cloning of a plant gene involved in fatty acid metabolism showing an induction during fruit ripening.
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  • 49
    ISSN: 1573-5028
    Keywords: pyruvate kinase ; plastid ; gene expression
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    Topics: Biology
    Notes: Abstract Clones encoding two different forms of plastid pyruvate kinase (PKp; EC 2.7.1.40) have been isolated from both castor and tobacco seed cDNA libraries. One form, designated PKpA, from castor was described in a previous report, and the tobacco homologue of PKpA has now been isolated. In addition, a second cDNA, designated PKpG, has been identified and sequenced in both species. Western blot analysis, using antibodies raised against protein overexpressed from these clones, indicates that they encode the two predominant polypeptides of plastid pyruvate kinase from developing castor endosperm. In castor, both PKpA and PKpG are encoded by single genes. In the allotetraploid Nicotiana tabacum, there are two copies of each, one derived from each of the progenitors of this species. The expression of the genes for PKpA and PKpG was examined in various tissues from both castor and tobacco. In castor, both forms are expressed in developing and germinating endosperm and in the root but neither is expressed in the leaf. In tobacco, both forms are expressed in developing seeds but in mature tissues, PKpA is most abundant in roots and PKpG in leaves.
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  • 50
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    Plant molecular biology 27 (1995), S. 327-338 
    ISSN: 1573-5028
    Keywords: gene expression ; multi-gene family ; phenylalanine ammonia-lyase ; phenylpropanoids ; promoters ; secondary metabolism
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    Topics: Biology
    Notes: Abstract Phenylpropanoid derivatives are a complex class of secondary metabolites that have many important roles in plants during normal growth and in responses to environmental stress. Phenylalanine ammonialyase (PAL) catalyzes the first step in the biosynthesis of phenylpropanoids, and is usually encoded by a multi-gene family. Genomic clones for three Arabidopsis thaliana PAL genes containing the entire protein-coding region and upstream and downstream sequences have been obtained and completely sequenced. Two A. thaliana PAL genes (PAL1 and PAL2) are structurally similar to PAL genes that have been cloned from other plant species, with a single intron at a conserved position, and a long highly conserved second exon. Previously identified promoter motifs plus several additional sequence motifs were found in the promoter regions of PAL1 and PAL2. Expression of PAL1 and PAL2 is both qualitatively and quantitatively similar in different plant organs and under various inductive conditions. A third A. thaliana PAL gene, PAL3, differs significantly from PAL1 and PAL2 and other sequenced plant PAL genes. PAL3 contains an additional intron, and its deduced amino acid sequence is less homologous to other PAL proteins. The PAL3 promoter region lacks several sequence motifs conserved between A. thaliana PAL1 and PAL2, as well as motifs described in other genes involved in phenylpropanoid metabolism. A. thaliana PAL3 was expressed at very low levels under the conditions examined.
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  • 51
    ISSN: 1573-5028
    Keywords: cis factor ; gene expression ; promoter ; transgenic rice ; wheat histone H3
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    Topics: Biology
    Notes: Abstract Type I element (CCACGTCACCGATCCGCG) is a well-conserved regulatory element found in proximal promoter region of a certain class of plant histone genes, that is composed of two independent cis-acting elements of the hexamer (ACGTCA) and the reverse-oriented octamer (GATCCGCG) motifs. To investigate functional role(s) of the type I element in regulation of a wheat histone H3 gene (TH012) promoter activity in vivo, base substitution mutations were introduced into the element and activities of the mutated promoters were examined in cultured rice cells, and in regenerated roots and anther walls of transgenic rice plants by employing a GUS reporter system. Mutations of each or both of the hexamer and the octamer motifs caused a reduction in the promoter activity in protoplasts transfected transiently or stably transformed calli. The mutation of the octamer motif with or without the mutation of the hexamer motif caused a marked reduction of the promoter activity in the root meristem of transgenic rice although the mutation of the hexamer motif alone caused a weak reduction. In contrast to these results, no effect of the mutations of either the hexamer or the octamer motif was found in the anther wall in which replication-independent activity of the H3 promoter was observed. Our results suggested that the hexamer and the octamer motifs may play important role(s) in regulation of replication-dependent but not of replication-independent expression of the wheat histone H3 gene.
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  • 52
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    Plant molecular biology 27 (1995), S. 743-752 
    ISSN: 1573-5028
    Keywords: plant hormone ; gibberellic acid ; GA-responsive ; gene expression ; HCA ; hydrophobic cluster analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A multiple gene family of at least four members, related to a GA-stimulated transcript (GAST1) from tomato, was characterized in Arabidopsis thaliana by analysing four related cDNAs, named GASA1 to GASA4. The corresponding peptides display comparable structural features: (1) a putative signal peptide of 18 to 23 residues; (2) a highly divergent hydrophilic region of about 22 amino acids; (3) a conservative 60 amino acid C-terminal domain containing 12 cysteines. This organization has also bean shown in two related peptides from tomato, GAST1 found in shoots and RSI-1 found in early lateral roots. Southern blot hybridization patterns showed single-copy genes for all four members of the GASA family. Accumulation of the various transcripts, monitored by northern blot hybridization, indicated that the various genes are expressed differentially in plant organs. Specific mRNAs were mostly detected in flower buds and immature siliques in the case of GASA1, in siliques and dry seeds in the case of GASA2 and 3, and in growing roots and flower buds in the case of GASA4. At least two of the GASA genes are activated in GA-deficient mutant ga5, as early as 4 to 8 h after spraying with 50 μM GA3. The complex patterns of expression and regulation of the various genes suggest that the related peptides are involved in a developmental regulation process in Arabidopsis.
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  • 53
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    Plant molecular biology 27 (1995), S. 953-967 
    ISSN: 1573-5028
    Keywords: calcium-dependent protein kinase ; gene expression ; protein phosphorylation ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated, from a cDNA library constructed from rice coleoptiles, two sequences, OSCPK2 and OSCPK11, that encode for putative calcium-dependent protein kinase (CDPK) proteins. OSCPK2 and OSCPK11 cDNAs are related to SPK, another gene encoding a rice CDPK that is specifically expressed in developing seeds [20]. OSCPK2 and OSCPK11-predicted protein sequences are 533 and 542 amino acids (aa) long with a corresponding molecular mass of 59436 and 61079 Da respectively. Within their polypeptide chain, they all contain those conserved features that define a plant CDPK; kinase catalytic sequences are linked to a calmodulin-like regulatory domain through a junction region. The calmodulin-like regulatory domain of the predicted OSCPK2 protein contains 4 EF-hand calcium-binding sites while OSCPK11 has conserved just one canonical EF-hand motif. In addition, OSCPK2-and OSCPK11-predicted proteins contain, at their N-terminal region preceding the catalytic domain, a stretch of 80 or 74 residues highly rich in hydrophilic amino acids. Comparison of the NH2-terminal sequence of all three rice CDPKs so far identified (OSCPK2, OSCPK11 and SPK) indicates the presence of a conserved MGxxC(S/Q)xxT motif that may define a consensus signal for N-myristoylation. OSCPK2 and OSCPK11 proteins are both encoded by a single-copy gene and their polyadenylated transcripts are 2.4 and 3.5 kb long respectively. OSCPK2 and OSCPK11 mRNAs are equally abundant in rice roots and coleoptiles. A 12 h white light treatment of the coleoptiles reduces the amount of OSCPK2 mRNA with only a slight effect on the level of OSCPK11 transcript. With anoxic treatments, OSCPK2 mRNA level declined significantly and promptly while the amount of OSCPK11 transcript remained constant.
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  • 54
    ISSN: 1573-5028
    Keywords: gene expression ; cyanobacterium ; nitrite reductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nitrite reductase (NiR) gene (nirA) has been isolated and sequenced from the filamentous, thermophilic non-N2-fixing cyanobacterium Phormidium laminosum. Putative promoter-like and Shine-Dalgarno sequences appear at the 5′ end of the 1533 bp long nir-coding region. The deduced amino acid sequence of NiR from P. laminosum corresponds to a 56 kDa polypeptide, a size identical to the molecular mass previously determined for the pure enzyme, and shows a high identity with amino acid sequences from ferredoxin-dependent NiR. This cyanobacterial NiR gene has been efficiently expressed in Escherichia coli DH5α from the E. coli lac promoter and probably from the P. laminosum NiR promoter.
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  • 55
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    Plant molecular biology 27 (1995), S. 1183-1188 
    ISSN: 1573-5028
    Keywords: differential screening ; maize ; pith ; trpA ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA derived from an abundant maize pith mRNA transcript and its corresponding genomic equivalent have been isolated and characterized. High transcript levels are seen in the pith and young leaves of maize plants, while no transcript is detected in seed tissue of any age. The protein encoded by the isolated gene has considerable homology with tryptophan synthase alpha subunit (trpA) from other organisms and the cDNA clone can complement an E. coli trpA mutant. These data support the conclusion that this cDNA and the corresponding genomic clone encode a maize trpA protein.
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  • 56
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    Plant molecular biology 29 (1995), S. 91-98 
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; gene expression ; hypersensitive response ; oxidative stress ; ozone ; pathogenesis-related proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used a reverse transcriptase polymerase chain reaction procedure (differential display) to isolate cDNAs corresponding to transcripts that accumulate in ozone-treated Arabidopsis thaliana. In this report we describe the characterization of an ozone-induced transcript, AtOZI1. AtOZI1 mRNA in untreated plants was detected at low levels in cotyledons, leaves, and flower buds and at higher levels in roots and mature flowers. AtOZI1 mRNA accumulation was transiently induced in leaves 3- to 5-fold within the first 6 h of ozone treatment. AtOZI1 mRNA accumulation was also transiently induced 3- to 6-fold by photopathogenic Pseudomonas strains. Sequence analysis of AtOZI1 revealed that it encodes a 8.6 kDa basic protein that contains a putative signal peptide and two potential phosphorylation sites. Our results suggest that AtOZI1 represents a novel stress-related protein that accumulates in response to the production of active oxygen species.
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  • 57
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    Plant molecular biology 29 (1995), S. 135-148 
    ISSN: 1573-5028
    Keywords: chromophyte ; Chrysophyceae ; light-harvesting complex protein gene ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated a gene from a library of nuclear DNA for a chlorophyll a/c-binding protein (named Cac for chl a/c by analogy with Cab for chl a/b) of a chromophyte alga, Giraudyopsis stellifer, and sequenced it. The comparison of the deduced amino acid sequence with other chl a/c-and chl a/b-binding protein sequences shows that structural and functional features, i.e. the arrangement ‘en X’ of the two A and B transmembrane helices and the putative chl a-binding sites, are shared by both Chlorophyta and Chromophyta. Moreover, in contrast to Chlorophyta, a very strong identity is found among Chromophyta in the C helix, suggesting a major function associated to this specific region. Nevertheless, the primary structure of the apoprotein does not seem affected by the pigment composition in Chromophyta. As in the few other examples currently known, we confirm that the cac genes are nuclear-encoded and are part of a multigenic family. Northern blots, performed on poly(A)+ mRNA from G. stellifer, give evidence that the cac gene is light-induced at a transcriptional level and that no expression can be observed in the dark.
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  • 58
    ISSN: 1573-5028
    Keywords: cathepsin B ; gene expression ; Nicotiana ; thiol protease
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    Topics: Biology
    Notes: Abstract Sequence analysis of a 1.33 kb clone from a root cDNA library of Nicotiana rustica revealed an open reading frame encoding a protein of 356 amino acids. The deduced protein has high levels of homology to human cathepsin B protease and a cathepsin B-like cysteine protease from wheat but much lower levels of homology with other plant cysteine proteinases. Southern blotting experiments suggest a limited number of cathepsin B-like genes are present in the genome of N. rustica and also that of N. tabacum. RNA analysis involving a range of tissues, harvested from both Nicotiana species 4–5 h after the beginning of a 16 h photoperiod, revealed the cathepsin B-like gene was being expressed strongly in roots, stem and developing flowers but weakly in mature leaves. Further analysis of RNA extracted from leaf tissue of N. tabacum revealed the gene showed rhythmic expression and also that its expression increased in response to wounding. Analysis of leaf tissues harvested during the latter part of a 16 h photoperiod (11 and 16 h after illumination commenced) showed that transcript levels were two three times higher than in leaf tissue harvested either towards the end of the dark period or 5 h after illumination commenced. When leaf tissue was wounded at 11:00 (5 h after plants were illuminated), and harvested for RNA extraction 6 h later, the level of cathepsin B-like transcript in mesophyll tissue was found to be increased ca. 2-fold relative to the level detected in unwounded controls.
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  • 59
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; chloroplast ; gene expression ; ω-3 fatty acid desaturase ; promoter ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Arabidopsis FAD7 gene encodes a chloroplast ω-3 fatty acid desaturase that catalyzes the desaturation of lipid-linked dienoic fatty acids (18:2 and 16:2). An 825 bp FAD7 promoter fragment upstream from the transcriptional start point contained several short sequences which were homologous to the cis-elements (box II, G-box, etc.) conserved in many light-responsive genes. We introduced the FAD7 promoter fused to the β-glucuronidase (GUS) or the luciferase (LUC) reporter gene into tobacco plants. The −825 promoter sequence conferred tissue-specific and light-responsive expression to both these reporter genes in transgenic tobacco, indicating that these expressions of the FAD7 gene were regulated mainly at the transcriptional level. Histochemical GUS staining showed that the activity of the FAD7 promoter is restricted to the tissues with chloroplast-containing cells although the staining was noticeably absent in the chloroplast-containing cells associated with vascular systems. The 5′ deletion experiments of the promoter revealed that the −362/ −166 region, containing two putative box II sequences, was responsible for the tissue-specific and light-responsive expression of the FAD7 gene.
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  • 60
    ISSN: 1573-5028
    Keywords: tomato ; polygalacturonase ; pectin methylesterase ; heat stress ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of extended heat stress on polygalacturonase (PG; EC 3.2.1.15) and pectin methylesterase (PME; EC 3.1.1.11) gene expression at mRNA, protein and activity levels in ripening tomato fruits were investigated. Steady state levels of PG mRNA declined at temperatures of 27°C and above, and a marked reduction in PG protein and activity was observed at temperatures of 32°C and above. Exogenous ethylene treatment did not reverse heat stress-induced inhibition of PG gene expression. Transfer of heat-stressed fruits to 20°C partly restored PG mRNA accumulation, but the rate of PG mRNA accumulation declined exponentially with duration of heat stress. Heat stress-induced inhibition of PME mRNA accumulation was recoverable even after 14 days of heat stress. In fruits held at 34°C, both PG and PME protein and activity continued to accumulate for about 4 days, but thereafter PG protein and activity declined while little change was observed in PME protein and activity. In spite of increases in mRNA levels of both PG and PME during the recovery of heat-stressed fruit at 20°C, levels of PG protein and activity declined in fruits heat-stressed for four or more days while PME protein and activity levels remained unchanged. Collectively, these data suggest that PG gene expression is being gradually and irreversibly shut off during heat stress, while PME gene expression is much less sensitive to heat stress.
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  • 61
    ISSN: 1573-5028
    Keywords: gene family ; gene expression ; photoreceptor ; phytochrome ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data presented here define five tomato phytochrome genes (PHY) and indicate the existence of additional PHY in the tomato genome. Portions of each gene, encoding amino acids 203 through 315 in a consensus amino acid sequence, were amplified by polymerase chain reaction. Four of these genes, PHYA, PHYB1, PHYB2 and PHYE, are members of previously identified PHY subfamilies, while the fifth, PHYF, is identified as a member of a new PHY subfamily. PHYA, PHYB1, PHYB2 and PHYE fragments encode amino acid sequences that share 88% to 98% sequence identity with their Arabidopsis counterparts. The PHYF fragment, however, encodes a polypeptide that shares only 65% to 74% sequence identity with previously identified Arabidopsis phytochromes. A phylogenetic analysis suggests that PHYF arose soon after, or perhaps prior to, the origin of angiosperms. This analysis leads to the prediction that PHYF might be widespread among angiosperms, including both monocotyledons and dicotyledons. Each of the five tomato PHY is expressed as a transcript of sufficient size to encode a full-length phytochrome apoprotein. Two PHYF transcripts, 4.4 and 4.7 kb in length, have been detected in 9-day-old light-grown seedlings, consistent with either multiple transcription start sites or differential processing. Analyses of genomic Southern blots hybridized with radiolabelled RNA probes derived from the five tomato PHY, as well as Arabidopsis PHYC, indicate that the tomato genome contains as many as 9 to 13 PHY. The tomato PHY family is apparently not only different from, but also larger than, the PHY family presently described for Arabidopsis.
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  • 62
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; tuberisation ; extensin ; acyl carrier protein thioesterase ; high mobility group protein ; gene expression ; plant development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In screening to isolate a full-length copy of a previously isolated cDNA clone, a further three cDNAs were also isolated from a library prepared from sub-apical swelling-stolon tissue of potato (Solanum tuberosum L.). Sequence analysis showed these clones to be similar to extensin-like protein genes, acyl carrier protein thioesterase genes and high mobility group protein genes, respectively. A further cDNA, isolated by subtractive hybridisation, was similar to a tomato cDNA previously isolated on the basis of its down-regulation following nematode infection. While all the newly isolated genes were expressed in swelling stolons, for most, maximal expression was seen to be in stem tissue. Possible roles for these genes in the development of potato plants are discussed, as is the significance of gene expression in stems and stolons to the process of tuberisation.
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  • 63
    ISSN: 1573-9368
    Keywords: human α1AT ; CAT ; transgenic mice ; gene expression ; liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The tissue-specific and developmental pattern of expression controlled by the proximal promoter (position −348 to+15) derived from the human α-1-antitrypsin (hα1AT) gene was studied in transgenic mice. The short promoter segment was linked to the chloramphenicol acetyltransferase (CAT) reporter gene. The transgene showed highly specific expression in the liver and the correct developmental pattern of regulation. Interestingly, this short promoter targets expression to the liver with a greater specificity than that reported for larger α1AT promoter fragments.
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  • 64
    ISSN: 1573-9368
    Keywords: gene expression ; transgenic mice ; thyroid hormone ; thyroid hormone response element ; muscle ; heart
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During development in the murine ventricle, there is a switch in myosin heavy chain gene (MyHC) transcription. The β-MyHC is expressed in the ventricles during foetal development, but is shut down at or around birth, at which time α-MyHC transcription is activated. This antithetical switch is thought to be mediated by circulating levels of thyroid hormone (TH) and both low and high affinity thyroid response elements (TREs) have been identified in the proximal promoter region of the murine α-MyHC. Myosin gene expression in the atria is relatively unaffected by the TH status. Previously, we used site-directed mutagenesis of the promoter in a transgenic analysis to define those elements responsible for high levels of transcriptionin vivo. These analyses focused on the role(s) of twocis elements, TRE1 and TRE2 that are located at −129 to −149 and −102 to −120, respectively, on the α-MyHC promoter. Although the elements' ablation had differential effects on transgene expression, neither single mutation abolished transgene expression completely. Here, we show that mutating both elements results in a complete inactivation of the transgene in both ventricles and atria under euthyroid conditions. However, expression still can be detected in the hyperthyroid state, implying that, although the TRE1 and TRE2 elements are critical elements for high levels of α-MyHC transcriptionin vivo, other promoter sites can mediate at least some degree of transcriptional activation.
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  • 65
    ISSN: 1573-9368
    Keywords: transgenic mice ; prolactin ; mammary gland ; gene expression ; Stat5 ; β-globin insulator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to establish a possible correlation between in vitro prolactin induction and the transcriptional activity of mammary gene promoters in transgenic mice, a functional Stat5-binding site was created by means of site-directed mutagenesis at position −70 on a 560 bp murine α-lactalbumin promotor linked to a CAT reporter gene. Surprisingly, the wild-type promoter was constitutively active in vitro and could not be induced by prolactin. Introducing the proximal Stat5 site abolished this constitutive activity and resulted in prolactin dependence in both CHO-K1- and HC11-transfected cells. In transgenic mice, both the frequency of lines expressing the transgene and the prevalence of mid to late pregnancy expression were increased.
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  • 66
    ISSN: 1573-0778
    Keywords: CHO cells ; gene expression ; kinetic model ; protein secretion ; transcription ; translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The elevation of expression levels for secreted glycoproteins by gene amplification in mammalian cells shows a saturation behavior at high levels of gene amplification. At high expression levels a drop in the secretion efficiency for the recombinant protein occurs (Schröder and Friedl, 1997), coinciding with the appearance of misfolded protein in the cell. In this communication we investigated whether additional limitations exist at the levels of transcription and translation. Four Chinese hamster ovary (CHO) cell lines expressing different amounts of human antithrombin III (ATIII) were used as a model system. A tenfold increase in the ATIII cDNA copy number from the lowest to the highest producing cell line coincided with a 38-fold increase in ATIII mRNA levels, and an 80-fold increase in the amount of intracellular ATIII levels. The data was analyzed using a simple kinetic model. The following conclusions were derived: I. The transcriptional activity for the recombinant protein is not saturated. II. Translation itself is not saturated either, but may be downregulated as secretion efficiency drops. III. Two explanations for the previously reported drop in secretion efficiency for the recombinant protein with increasing expression level are possible: A. Protein degradation is an alternative fate for translated ATIII and the fraction of ATIII degraded after translation increases as expression level is increased. B. Translation is downregulated as the secretory apparatus becomes exhausted to maintain cell viability.
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  • 67
    ISSN: 1573-0778
    Keywords: cardiogenesis ; cell differentiation ; gene expression ; mouse embryonic stem cells ; myogenesis ; neurogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Embryonic stem cells, totipotent cells of the early mouse embryo, were established as permanent cell lines of undifferentiated cells. ES cells provide an important cellular system in developmental biology for the manipulation of preselected genes in mice by using the gene targeting technology. Embryonic stem cells, when cultivated as embryo-like aggregates, so-called ‘embryoid bodies’, are able to differentiate in vitro into derivatives of all three primary germ layers, the endoderm, ectoderm and mesoderm. We established differentiation protocols for the in vitro development of undifferentiated embryonic stem cells into differentiated cardiomyocytes, skeletal muscle, neuronal, epithelial and vascular smooth muscle cells. During differentiation, tissue-specific genes, proteins, ion channels, receptors and action potentials were expressed in a developmentally controlled pattern. This pattern closely recapitulates the developmental pattern during embryogenesis in the living organism. In vitro, the controlled developmental pattern was found to be influenced by differentiation and growth factor molecules or by xenobiotics. Furthermore, the differentiation system has been used for genetic analyses by ‘gain of function’ and ‘loss of function’ approaches in vitro.
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  • 68
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    Cytotechnology 30 (1999), S. 71-83 
    ISSN: 1573-0778
    Keywords: gene expression ; HEK293(EBNA) cells ; serum-free ; transient transfection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In order to establish a simple and scaleable transfection system we have used the cationic polymer polyethylenimine (PEI) to study transient transfection in HEK293 and 293(EBNA) cells grown in serum-free suspension culture. The transfection complexes were made directly within the cell culture by consecutively adding plasmid and PEI (direct method). Alternatively, the DNA-PEI transfection complexes were prepared in fresh medium (1/10 culture volume) and then added to the cells (indirect method). The results of this study clearly show that the ratio of PEI nitrogen to DNA phosphate is very important for high expression levels. The precise ratio is dependent on the DNA concentration. For example, using 1 μg/ml DNA by the indirect method, the ratio of optimal PEI:DNA was about 10–13:1. However, the ratio increases to 33:1 for 0.1–0.2 μg/ml DNA. By testing several different molecular weights of the polycationic polymer we could show that the highest transfection efficiency was obtained with the PEI 25 kDa. Using PEI 25 kDa the indirect method is superior to the direct addition because significantly lower DNA concentrations are needed. The expression levels of the soluble human TNF receptor p55 are even higher at low DNA compared to 1 μg/ml plasmid. The EBV-based pREP vectors gave better transient gene expression when used in 293(EBNA) cells compared to HEK293 cells in suspension culture. No differences in expression levels in the two cell lines were observed when the pC1 (CMV)-TNFR was used. In conclusion, PEI is a low-toxic transfection agent which provides high levels of transient gene expression in 293(EBNA) cells grown in serum-free suspension culture. This system allows highly reproducible, cost-effective production of milligram amounts of recombinant proteins in 2–5 l spinner culture scale within 3–5 days. Fermentor scale experiments, however, are less efficient because the PEI-mediated transient tranfection is inhibited by conditioned medium.
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  • 69
    ISSN: 1573-0778
    Keywords: cell cycle ; CHO ; flow cytometry ; gene expression ; synchronisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Understanding the relationships between cell cycle and protein expression is critical to the optimisation of media and environmental conditions for successful commercial operation of animal cell culture processes. Using flow cytometry for the analysis of the early phases of synchronised batch cultures, the dependency of product expression on cell cycle related events has been evaluated in a recombinant CHO cell line. Although the production of recombinant protein is initially found to be cell cycle related, the maximum specific protein productivity is only achieved at a later stage of the exponential phase which also sees a maximum in the intracellular protein concentration. Subsequent work suggests that it is the batch phase/medium composition of cultures which is the major determinant of maximum specific productivity in this cell line. Furthermore the effect of the positive association between S phase and specific productivity is subordinate to the effect of batch phase/medium composition on the specific productivity of batch cultures.
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  • 70
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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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  • 71
    ISSN: 1573-4935
    Keywords: Mucin ; lung cancer ; gene expression ; secretion ; lung adenocarcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mucins comprise an important class of tumor-associated antigens. The objectives of the present study were (a) to establish an in vitro model system using human non-small cell lung adenocarcinoma cell lines NCIH650 and NCIH2077 (b) provide evidence that these cell lines secrete mucin in culture conditions and (c) investigate the effects of select secretagogues on mucin secretion. The cell lines were established in ACL-4 medium containing several growth factors and retinoic acid and 5% fetal calf serum. The high molecular weight glycoconjugates secreted in the culture medium were purified by ammonium sulfate precipitation and Superose 6 and Superose 12 FPLC chromatography. The purified high molecular weight glycoconjugate fraction and the carcinoma cells were shown to have mucin by dot blot, Western blot and immunohistochemical analysis, respectively, using specific antibodies to purified major mucin, HTM-1. Also, incorporation experiments with mucin precursor 3H-glucosamine demonstrated that the cells indeed synthesize high molecular weight mucins. The effects of secretagogues such as, 8-bromocyclic AMP, ionomycin, phorbol-12-myristate-13-acetate and neutrophil elastase on mucin secretion were also investigated. Only 8-bromocyclic AMP and neutrophil elastase influenced mucin secretion. These studies provided strong evidence that the lung adenocarcinoma cell lines secrete high molecular weight mucins in culture conditions and only two of the four tested secretagogues significantly increased mucin secretion. Thus, this in vitro model system may be useful in determining alterations in mucin structure, if any, in lung adenocarcinomas as well as in studying the regulation of mucin gene expression.
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  • 72
    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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  • 73
    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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  • 74
    ISSN: 1573-5028
    Keywords: amphidiploid genome structure ; gene expression ; glutamine synthetase ; multigene family ; nitrogen assimilation ; oilseed rape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the amphidiploid genome of oilseed rape (Brassica napus) the diploid ancestral genomes of B. campestris and B. oleracea have been merged. As a result of this crossing event, all gene loci, gene families, or multigene families of the A and C genome types encoding a certain protein are now combined in one plant genome. In the case of the multigene family for glutamine synthetase, the key enzyme of nitrogen assimilation, six different cDNA sequences were isolated from leaf and root specific libraries. One sequence pair (BnGSL1/BnGSL2) was characterized by the presence of amino- terminal transit peptides, a typical feature of all nuclear encoded chloroplast proteins. Two other cDNA pairs (BnGSR1-1/BnGSR1-2 and BnGSR2-1/BnGSR2-2) with very high homology between each other were found in a root specific cDNA library and represent protein subunits for cytosolic glutamine synthetase isoforms. Comparative PCR amplifications of genomic DNA isolated from B. napus, B. campestris and B. oleracea followed by sequence–specific restriction analyses of the PCR products permitted the assignment of the cDNA sequences to either the A genome type (BnGSL1/BnGSR1- 1/BnGSR2-1) or the C genome type (BnGSL2/BnGSR1-2/BnGSR2-2). Consequently, the ancestral GS genes of B. campestris and B. oleracea are expressed simultaneously in oilseed rape. This result was also confirmed by RFLP (restriction fragment length polymorphism) analysis of RT-PCR products. In addition, the different GS genes showed tissue specific expression patterns which are correlated with the state of development of the plant material. Especially for the GS genes encoding the cytosolic GS isoform BnGSR2, a marked increase of expression could be observed after the onset of leaf senescence.
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  • 75
    ISSN: 1573-5028
    Keywords: defense ; gene expression ; leaf senescence ; nitrilase ; pathogen-free ; salicylic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To determine the range of gene activities associated with leaf senescence, we have identified genes that show preferential transcript accumulation during this developmental stage. The mRNA levels of a diverse array of gene products increases during leaf senescence, including a protease, a ribosomal protein, two cinnamyl alcohol dehydrogenases, a nitrilase and glyoxalase II. Two of the genes identified are known to be pathogen-induced. The senescence specificity of each gene was determined by characterization of transcript accumulation during leaf development and in different tissues. The increased expression of nitrilase in senescent leaves is paralleled by an increase in free indole-3-acetic acid (IAA) levels. Additionally, we have demonstrated that the induction of defense-related genes during leaf senescence is pathogen-independent and that salicylic acid accumulation is not essential for this induction. Our data indicate that the induction of certain genes involved in plant defense responses is a component of the leaf senescence program.
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  • 76
    ISSN: 1573-5028
    Keywords: gene expression ; gibberellin ; H1 histone ; H2B histones ; leaf ; Lycopersicon esculentum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract After differential screening we isolated cDNA clones encoding a histone H1 (leH1) and three variants of histone H2B (leH2B-1, -2 and -3) from the gibberellin (GA)-deficient mutant of tomato (gib-1). The deduced polypeptide of leH1 is 271 amino acids long and exhibits the typical tripartite structure of histones H1. The full-length cDNA clone leH2B-1 encodes for a protein of 142 amino residues and shows the tripartite organization of histones H2B. The histones leH1 and leH2B, which show no tissue specificity, are developmentally expressed in the leaf. The mRNA accumulation was higher in organs which contain meristematic tissue and/or which have a high proportion of actively cycling cells. In the leaf of the gib-1 mutant we demonstrated GA-enhanced histone leH1 and leH2B expression which was not observed in the wild type. GAs of the early-13-hydroxylated pathway (GA1 and GA3) caused most enhanced transcription compared to GAs of the early-non-hydroxylation pathway (GA4 and GA9). Application of GA to the mutant increased histone expression that could correlate with enhanced DNA replication in leaf tissue. Increased chromosome replication may indicate that there is a higher rate of cell division and/or increase of endopolyploidy which both may be dependent on cell elongation induced by GAs.
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  • 77
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    Plant molecular biology 39 (1999), S. 933-943 
    ISSN: 1573-5028
    Keywords: cloning ; fruit development ; gene expression ; pea ; polyamine ; spermidine synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two cDNAs from young pea fruits coding for functional spermidine synthases (EC 2.5.1.16) were isolated. The corresponding genes were named psSPDSYN1 and psSPDSYN2. Both cDNAs complemented spe3Δ gene when introduced into the Y480 strain of Saccharomyces cerevisiae, which is a null mutant for the spermidine synthase gene. psSPDSYN1 and psSPDSYN2 are regulated differentially. psSPDSYN1 is up-regulated early after fruit set whereas psSPDSYN2 is expressed later. Spermidine synthase activity was detected in pea ovaries, and correlates with the pattern of expression of psSPDSYN1. In the pea plant, psSPDSYN1 is highly expressed in actively growing tissues, whereas the highest level of psSPDSYN2 mRNA was detected in fully elongated stem.
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  • 78
    ISSN: 1573-5028
    Keywords: chitin oligomer ; chitinase ; elicitor ; gene expression ; rice ; signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression patterns of chitinase transcripts induced by N-acetylchitooligosaccharide elicitor were analyzed by northern blot hybridization in order to reveal a signal transduction pathway leading to the activation of class I chitinase genes (Cht-1 and Cht-3), which may play an important role in producing N-acetylchitooligosaccharide elicitor. The transcription level of both genes was enhanced in response to N-acetylchitooligosaccharides larger than pentaose at subnanomolar concentrations. These structure and dose dependencies were consistent not only with those for a 75 kDa high-affinity binding protein for N-acetylchitooligosaccharide elicitor in the plasma membrane, but also with other series of cellular responses including phytoalexin production and the expression of elicitor-responsive genes (EL2, EL3). Therefore, the elicitor signal to evoke these cellular responses including the activation of the chitinase genes could be common and transmitted into cells through the 75 kDa protein. However, the signal transduction pathway for the activation of the chitinase gene appeared to diverge from those for the other elicitor-responsive genes shortly after the signal perception. It was shown that the induction of chitinase expression by N-acetylchitooligosaccharide would require protein phosphorylation, but not de novo protein synthesis. The oxidative burst was demonstrated not to be necessary for transcriptional induction of the all four elicitor-responsive genes (Cht, PAL, EL2, EL3) by N-acetylchitooligosaccharide.
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  • 79
    ISSN: 1573-5028
    Keywords: cytochrome b5 ; fruit and flower development ; gene expression ; in situ hybridisation ; olive
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report the characterisation of two cytochrome b5 genes and their spatial and temporal patterns of expression during development in olive, Olea europaea. A PCR-generated probe, based on a tobacco cytochrome b5 sequence, was used to isolate two full-length cDNA clones (cytochrome b5-15 and cytochrome b5-38) from a library derived from 13 WAF olive fruits. The cDNAs encoded proteins of 17.0 and 17.7 kDa, which contained all the characteristic motifs of cytochromes b5 from other organisms and exhibited 63% identity and 85% similarity with each other. The olive cytochrome b5-15 cDNA was then used as a probe for more detailed analysis. Southern blotting revealed a gene family of at least 4–6 members while northern blotting and in situ hybridisation showed a highly specific pattern of gene expression. Very low levels of cytochrome b5 mRNA were detected in tissues characterised by high rates of lipid accumulation, such as young expanding leaves, maturing seeds and ripening mesocarp. The cytochrome b5 genes were not induced at 6 °C and their response to ABA was relatively slow compared with fatty acid desaturase genes. In contrast, high levels of cytochrome b5 gene expression were found in young fruits at the pattern formation (globular/heart) stage of embryogenesis and in vascular and transmitting tissues of male and female reproductive organs. The data are consistent with a major role for cytochrome b5 in developmental processes related to plant reproduction in addition to being an electron donor to microsomal desaturases.
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  • 80
    ISSN: 1573-5028
    Keywords: Amaranthus hypochondriacus) ; gene expression ; trypsin inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We previously isolated and sequenced the major trypsin inhibitor from Amaranthus hypochondriacus seeds. This amaranth trypsin inhibitor (AmTI) is a 69 amino acid protein with high homology to members of the potato-1 inhibitor family. This paper describes the cloning and expression of a cDNA encoding this trypsin inhibitor in various vegetative tissues of the amaranth plant during seed development and imbibition, and investigates the possible induction of AmTI expression by wounding. We obtained a 393 bp cDNA sequence with an open reading frame corresponding to a polypeptide with 76 amino acid residues. With the exception of one residue (Ser-41), the polypeptide agrees with the amino acid sequence previously reported, plus 7 more residues at the N-terminus. These N-terminal residues are thought to be part of the signal used for intracellular sorting. The organ specificity of AmTI gene expression was investigated by northern analysis, showing that mRNA corresponding to AmTI genes was present in stems of plants growing under normal conditions. The kinetics of accumulation of the AmTI-mRNA, protein, and inhibitory activity during seed development and imbibition was determined. AmTI-mRNA accumulation reached a maximum at 14 days after anthesis (daa) and then gradually decreased, being barely detectable 36 daa. The AmTI protein accumulation followed the same profile as the inhibitory activity, both were delayed with respect to the mRNA. The maximum level was observed 22 daa, and then gradually decreased until a steady state was reached as seed maturation proceeded. Upon imbibition, a gradual decrease in AmTI protein and inhibitory activity was shown; however, an AmTI transcript was detected 24 h after imbibition. In contrast to representative members of the potato I family, this inhibitor was not inducible by wounding of leaves.
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  • 81
    ISSN: 1573-5028
    Keywords: embryo ; gene expression ; Glycine max ; oxidoreductase ; seed coat ; testa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The soybean Ep gene encodes an anionic peroxidase enzyme that accumulates in large amounts in seed coat tissues. We have isolated a second peroxidase gene, Prx2, that is also highly expressed in developing seed coat tissues. Sequence analysis of Prx2 cDNA indicates that this transcript encodes a cationic peroxidase isozyme that is far removed from Ep in peroxidase phylogeny. To determine the expression patterns for these two peroxidases in developing seeds, the abundance and localization of the Ep and Prx2 transcripts were compared by in situ hybridization. Results show the expression of Ep begins in a small number of cells flanking the vascular bundle in the seed coat, spreads to encircle the seed, and then migrates to the hourglass cells as they develop. Expression of Prx2 occurs throughout development in all cell layers of the seed coat, and is also evident in the pericarp and embryo. Nonetheless, the Ep-encoded enzyme accounts for virtually all of the peroxidase activity detected in mature seed coats. The Prx2 enzyme is either insoluble in a catalytically inactive form, or is subject to degradation during seed maturation.
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  • 82
    ISSN: 1573-5028
    Keywords: ABRE ; embryogenesis ; G-box ; gene expression ; maize ; protein-DNA interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcription of the rab28 gene from maize is induced in late embryo development and in response to abscisic acid. We have studied the regulation of the activity of the rab28 promoter in embryos. Two abscisic acid-responsive elements (ABREs) were necessary for expression in embryos of transgenic Arabidopsis and in transient transformation in maize embryos. In vivo footprinting showed that there was protein binding to the ABREs and to other cis elements in the promoter in young embryos before expression of rab28. This shows that the rab28 promoter is in an open chromatin structure before developmental activation. The ABREs are important for the induction and have protein binding in young embryos. Nuclear proteins extracted from embryos before activation of rab28 bound to the ABREs in band shift assays. A complex with different mobility was formed between nuclear proteins and the ABREs after induction of rab28 suggesting a modification of the ABRE-binding factor or an exchange of proteins. The footprints on the ABREs were unaltered by induction with abscisic acid or during developmental activation of rab28. These results indicate that constitutive binding of transcription factor(s) on the ABRE is central in embryonic regulation of the rab28 gene.
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  • 83
    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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  • 84
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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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  • 85
    ISSN: 1573-5028
    Keywords: cDNA cloning ; fruit ripening ; gene expression ; non-climacteric fruit ; wild strawberry (Fragaria vesca L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wild strawberry (Fragaria vesca L.) is an attactive model system for studying ripening in non-climacteric fruit, because of its small diploid genome, its short reproductive cycle, and its capacity for transformation. We have isolated eight ripening-induced cDNAs from this species after differential screening of a cDNA library. The predicted polypeptides of seven of the clones exhibit similarity to database protein sequences, including acyl carrier protein, caffeoyl- CoA 3-O-methyltransferase, sesquiterpene cyclase, major latex protein, cystathionine γ-synthase, dehydrin and an auxin- induced gene. A ninth cDNA clone that was constitutively expressed is predicted to encode a metallothionein-like protein. None of these proteins appear to be directly related to events generally associated with ripening such as cell wall metabolism or the accumulation of sugars and pigments, rather, their putative functions are indicative of the wide range of processes upregulated during fruit ripening.
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  • 86
    ISSN: 1573-5028
    Keywords: cowpea (Vigna unguiculata L.) ; drought ; gene expression ; lipid degradation ; phospholipase D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phospholipase D, a major lipid-degrading enzyme in plants, was studied in two cultivars of Vigna unguiculata L.Walp, differing in their tolerance to drought (cv. EPACE-1, drought-tolerant, and cv. 1183, drought-susceptible). Enzymatic activities, measured with 14C-PC as substrate, increased when plants were submitted to water stress, the increase being much higher in the drought-sensitive cultivar. A 2911 bp cDNA encoding a putative phospholipase D (VuPLD1) was isolated from a cDNA library prepared from V. unguiculata leaves. The deduced amino acid sequence (809 residues) shows 85.5% identity and 91.3% similarity to that of PLD from Ricinus communis. The expression of the VuPLD1 gene in the leaves is differently modulated by water deficit, depending on the intensity of stress and the tolerance or sensitivity of the plants. In the drought-susceptible V. unguiculata cv. 1183, it readily increased under water stress, reaching maximum values at mild water deficit (−1.5 MPa). In the drought-tolerant cv. EPACE-1, VuPLD1 mRNA remained low throughout the whole drought treatment. Dehydration of leaves led to a dramatic increase in transcript level in both cultivars. Changes in protein amounts semi-quantified by immunoblotting correlated well with variations in transcript steady-state level. Taken together, these results showed that phospholipase D in cowpea plants is essentially regulated at the transcriptional level, and that gene expression is strongly stimulated even by moderate water deficit in the drought-sensitive plant. On the contrary, the drought-tolerant plant presents a remarkable stability of PLD gene expression in conditions of water stress.
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  • 87
    ISSN: 1573-5028
    Keywords: reproductive development ; gene expression ; subtractive hybridization ; cauliflower
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using the meristems of the cauliflower curd as a source of tissue and a series of subtractive hybridizations and amplification reactions, we have constructed a cDNA library highly enriched in cDNAs expressed in reproductive meristems. The analysis of a sample of 250 clones from this library identified 22 cDNA clones corresponding to genes specifically expressed in these cauliflower meristems. Apart from two clones that corresponded to APETALA1, and two other ones showing similarity to different aminoacyl-tRNA synthetases, the remaining clones showed no similarity to any sequence in the databases and may correspond to novel genes. One of these clones, BoREM1, was further characterized and found to correspond to a gene encoding a protein with features of regulatory proteins that follows a expression pattern very similar to the LEAFY transcripts.
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  • 88
    ISSN: 1573-5028
    Keywords: ammonium ; gene expression ; glutamine synthetase ; nodules ; positive element ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to identify important promoter elements controlling the ammonium-regulated expression of the soybean gene GS15 encoding cytosolic glutamine synthetase, a series of 5′ promoter deletions were fused to the GUS reporter gene. To allow the detection of positive and negative regulatory elements, a series of 3′ deletions were fused to a −90 CaMV 35S promoter fragment placed upstream of the GUS gene. Both types of construct were introduced into Lotus corniculatus plants and soybean roots via Agrobacterium rhizogenes-mediated transformation. Both spectrophotometric enzymatic analysis and histochemical localization of GUS activity in roots, root nodules and shoots of transgenic plants revealed that a strong constitutive positive element (SCPE) of 400 bp, located in the promoter distal region is indispensable for the ammonium- regulated expression of GS15. Interestingly, this SCPE was able to direct constitutive expression in both a legume and non- legume background to a level similar to that driven by the CaMV 35S full-length promoter. In addition, results showed that separate proximal elements, located in the first 727 bp relative to the transcription start site, are essential for root- and root nodule-specific expression. This proximal region contains an AAAGAT and two TATTTAT consensus sequences characteristic of nodulin or nodule-enhanced gene promoters. A putative silencer region containing the same TATTTAT consensus sequence was identified between the SCPE and the organ-specific elements. The presence of positive, negative and organ-specific elements together with the three TATTTAT consensus sequences within the promoter strongly suggest that these multiple promoter fragments act in a cooperative manner, depending on the spatial conformation of the DNA for trans-acting factor accessibility.
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  • 89
    ISSN: 1573-5028
    Keywords: embryo-abundant cDNAs ; gene expression ; gymnosperm ; Picea glauca ; somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six somatic embryogenesis-associated cDNAs (PgEMB2, 6, 7, 8, 24 and 34) from white spruce (Picea glauca (Moench) Voss) somatic embryos have been characterized. Transcript accumulation during somatic embryo development and subsequent germination related to these genes, indicated that they were developmentally regulated. The transcripts related to clones PgEMB2, 6, 24 and 34 were also detected during zygotic embryo development, but transcripts of clones PgEMB7 and 8 were not. PgEMB24 had a similar gene expression pattern to spruce Em-like late embryo abundant (lea) gene, but other clones had no similarities in gene expression to either spruce lea-like or storage protein genes. Abscisic acid, a stimulator for spruce somatic embryo maturation, did not obviously affect gene expression corresponding to these cDNAs. The predicted proteins are distinguishable from known LEA proteins based on analyses of hydropathy plots, amino acid compositions and deduced protein structures. The similarities of the spruce cDNAs, and protein sequences predicted from these cDNAs, to other sequence data are described.
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  • 90
    ISSN: 1573-5028
    Keywords: gene expression ; GT-1 ; PR-1a ; PR proteins ; salicylic acid-induced ; transcription factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Infection of Nicotiana tabacum Samsun NN with tobacco mosaic virus (TMV) results in a hypersensitive plant response and leads to systemic acquired resistance (SAR). The induction of SAR is mediated by the plant hormone salicylic acid (SA) and is accompanied by the induced expression of a number of genes including the pathogenesis-related (PR) gene 1a. Previously, it has been found that TMV infection and SA treatment resulted in a reduction of binding of nuclear protein GT-1 to far-upstream regions (−902 to −656) of the PR-1a gene. To test if GT-1 is a negative regulator of PR-1a gene expression, the effects of mutations in the seven putative GT-1 binding sites in this region were studied in vitro using dimethyl sulfate interference footprinting and band shift assays. This showed that at least one of the seven sites is indeed a GT-1 binding site. However, when tested in transgenic plants, the mutations did not result in constitutive expression of the chimeric PR-1a/GUS transgene, while inducible expression after SA treatment was decreased. The results suggest that binding of GT-1-like proteins to far-upstream PR-1a promoter regions indeed influences gene expression. A possible model for GT-1's mode of action in PR-1a gene expression is discussed.
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  • 91
    ISSN: 1573-5028
    Keywords: aquaporin ; gene expression ; growth ; Oryza sativa ; plasma membrane intrinsic protein (PIP) ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Membrane intrinsic proteins facilitate movement of small molecules often times functioning as water channels. We have identified two genes from rice which encode proteins with characteristic features of plasma membrane intrinsic proteins (PIP). They possess six membrane-spanning domains, an NPA repeat, overall high sequence homologies and characteristic C- and N-terminal hallmark motifs which allowed assignment of OsPIP1a to the PIP1 subfamily and of OsPIP2a to the PIP2 subfamily. OsPIP1a and OsPIP2a showed similar but not identical expression patterns. The two genes were expressed at higher levels in seedlings than in adult plants and expression in the primary root was regulated by light. In internodes of deepwater rice plants which were induced to grow rapidly by submergence, transcript levels were slightly induced in the intercalary meristem (IM) and slightly reduced in the elongation zone (EZ) after 18 h. In internodes of GA-induced excised stem sections transcript levels transiently declined in the IM and EZ after 1 h and subsequently recovered to elevated levels after 18 h. GA also induced OsPIP expression in non-growing tissue after 18 h. In the IM of submergence-induced stem sections transcript levels remained constitutive. The different growth-promoting treatments showed no direct correlation between growth rate and OsPIP gene expression in dividing or expanding cells. In fact, treatment of excised stem sections with ABA or drought stress induced similar changes in OsPIP expression in the growing zone during the first 6 h as GA did. We conclude that regulation of OsPIP1a and OsPIP2a expression is not primarily controlled by growth. GA-induced growth may however change the water status of cells which in turn results in altered PIP abundance.
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  • 92
    ISSN: 1573-5028
    Keywords: ACC synthase ; chilling ; Citrus sinensis ; ethylene ; gene expression ; peel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diurnal change in the temperature below or above 12.5 °C hastens the degreening of citrus peel and elicits the phytohormone ethylene production in citrus fruit. Ethylene triggers the degradation of chlorophyll and synthesis of carotenoids in citrus peel. To investigate if ethylene is required for the degreening of citrus peel elicited by low temperatures, we studied the chilling-regulated gene expression of ACC synthase, one of the key enzymes catalyzing ethylene biosynthesis. We isolated and characterized a chilling-inducible 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) gene, CS-ACS1, and a chilling-repressible gene, CS-ACS2, from citrus peel. The CS-ACS1 transcript 1.7 kb in length encodes a polypeptide of 483 amino acids (M r 54 115, pI 6.63), whereas the CS-ACS2 transcript of 1.8 kb encodes a polypeptide of 477 amino acids (M r 53 291, pI 6.72). Both genes showed a rapid but transient induction (within 2.4 h) of transcripts upon rewarming after the chilling (4 °C) treatment. After 24 h of incubation at room temperature, CS-ACS1 mRNA diminished to an undetectable level, whereas the CS-ACS2 mRNA regained its basal level of expression attained prior to the chilling treatment. Chilling-induced ethylene production and ACC accumulation were also observed upon rewarming. Both genes were also induced by the wound stress (excision). The protein synthesis inhibitor cycloheximide super-enhances the accumulation of both ACS transcripts at room temperature. Molecular analysis of the 3.3 kb genomic DNA of CS-ACS1 revealed that this gene consists of three introns and four exons. The intron 3 is exceptionally large (1.2 kb) and shares significant homology with mitochondrial DNA, supporting the intron-late theory.
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  • 93
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    Plant molecular biology 41 (1999), S. 351-361 
    ISSN: 1573-5028
    Keywords: chromatin ; gene expression ; high-mobility-group protein HMG1 ; HMGe ; protein stability ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nuclear HMG1 proteins of higher plants are small non-histone proteins that have DNA-bending activity and are considered architectural factors in chromatin. The occurrence of the chromosomal HMG1 proteins, HMGa, HMGc1/2 and HMGd, in various maize tissues was analyzed, and in the course of these studies a novel HMG1 protein, now termed HMGe, was identified. Purification and characterization of HMGe (Mr 13 655) and cloning of the corresponding cDNA revealed that it displays only moderate similarity to other members of the plant HMG1 protein family. The five maize HMG1 proteins could be detected in kernels, leaves, roots and suspension culture cells, indicating that these proteins can be expressed simultaneously and occur relatively ubiquitously. However, the various HMG1 proteins are present in significantly different quantities with HMGa and HMGc1/2 being the most abundant HMG1 proteins in all tissues tested. Furthermore, the relative amounts of the various HMG1 proteins differ among the tissues examined. The HMG1 proteins were found to be relatively stable proteins in vivo, with HMGc1/2, HMGd and HMGe having a half-life of ca. 50 h in cultured cells, while the half-life of the HMGa protein is ca. 65 h. Collectively, these findings are compatible with the concept that the different plant HMG1 proteins might act as general architectural proteins in concert with site-specific factors in the assembly of certain nucleoprotein structures involved in various biological processes.
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  • 94
    ISSN: 1573-5028
    Keywords: alkaloids ; gene expression ; Nicotiana tabacum ; nicotine ; putrescine N-methyltransferase ; tobacco gene evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structure and nuclear genomic organization of the gene family encoding putrescine N-methyltransferase (PMT), the key enzyme in diverting polyamine metabolism towards the biosynthesis of nicotine and related alkaloids, was examined in Nicotiana tabacum. Five genes encoding PMT are present in the N. tabacum genome and all are expressed. The complete coding region and immediate 5′- and 3′- flanking regions were characterized for four members of the gene family and the Exon 1 region of the fifth member of the family was determined. Comparison of the nucleotide and deduced amino acid sequences of the N. tabacum PMT genes with those of presumed progenitor species, N. sylvestris, N. tomentosiformis and N. otophora, revealed that three members of the N. tabacum PMT gene family were most similar to the three genes present in N. sylvestris, whereas the two remaining PMT genes were similar to PMT genes present in N. tomentosiformis and N. otophora genomes, respectively. These data are consistent with an evolutionary origin of N. tabacum resulting from a cross involving N. sylvestris and an introgressed hybrid between N. tomentosiformis and N. otophora. The five PMT genes present in N. tabacum are expressed in the roots of wild-type plants, but not in other organs. The steady-state level of all five PMT transcripts is transiently increased in roots following topping (removal of the floral meristem), although the maximum level of induction for the individual transcripts varies considerably. In contrast to wild-type plants, no increase in PMT transcript levels was observed in a low-alkaloid (nic1nic2) mutant of Burley 21. These data support a role for nic1 and nic2 in the global regulation of alkaloid formation in tobacco and provide for the first time molecular confirmation of the presumed origin of cultivated tobacco.
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  • 95
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    Plant molecular biology 41 (1999), S. 425-433 
    ISSN: 1573-5028
    Keywords: D1 protein ; gene expression ; psbA genes ; redox regulation ; Synechococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three psbA genes encode two different forms of the photosystem II reaction centre protein D1 in Synechococcus sp. PCC 7942. The psbAI gene encoding D1 protein form I (D1:1) is mainly expressed under low growth light conditions while the psbAII and psbAIII genes, encoding D1 protein form II (D1:2), are induced under stress conditions (e.g. high light or low temperature). In this paper we show that psbAII/III genes can be rapidly induced even under low growth light conditions by adding the thiol reductant (DTTred) to Synechococcus cell culture, at a concentration that does not affect cell growth or photosynthetic activity. Similar induction of psbAII/III genes was obtained by illuminating the cells with photosystem I light. In both instances psbAI gene down-regulation coincided with the up-regulation of psbAII/III genes. DTTred-induced exchange in transcript pools was subsequently followed by an exchange of D1:1 for D1:2 at the protein level. Thiol oxidants, iodosobenzoic acid or diamide, reverted the effects of DTTred on psbA gene expression. Thiol oxidants and the thiol-modifying agent N-ethylmaleimide also totally prevented high-light induction of psbAII/III genes. These data strongly suggest that the up-regulation of psbAII/III genes that occurs under stress conditions is mediated by production of thiol reductants, whereas the expression of the psbAI gene is sustained by the more oxidizing conditions that prevail during the steady-state growth of cells.
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  • 96
    ISSN: 1573-5036
    Keywords: ammonium assimilation ; Amanita muscaria ; carbon allocation ; ectomycorrhiza ; gene expression ; Picea abies ; sugar transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The symbiosis (ectomycorrhiza, ECM) between roots of trees and shrubs of boreal and temperate forest ecosystems and soil fungi is essential for water and nutrient acquisition of the plants. The functionality of ECM is largely dependent on the ability of the host plant to supply photoassimilates to the fungus via the symbiotic interface. Based on sterile in vitro and non-sterile pot experiments, we review data which gives evidence that hexoses are supplied to the fungus by the host plant (mainly glucose and fructose), and that these sugars, at least in part, control development and function of ECM by interfering with fungal gene expression. We further show that any factor which reduces hexose allocation to the host–fungus interface will adversely affect ECM development. As an example, we address the impact of increased supply of nitrogen on the biochemistry of plant–fungus interaction and discuss potential consequences on host performance.
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  • 97
    ISSN: 1573-5028
    Keywords: bundle sheath cell ; C4 photosynthesis ; gene expression ; PEP carboxykinase ; prokaryotic expression ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We isolated a full-length cDNA that encodes ATP-dependent phosphoenolpyruvate carboxykinase (EC 4.1.1.49, PCK) from leaves of maize, an NADP-malic enzyme type C4 plant. The mRNA was specifically and rather abundantly expressed in bundle sheath cells in accordance with the recent finding of cell-type-specific localization of PCK protein in maize, which has been detected with antibodies against cucumber PCK protein. The predicted protein had an N-terminal extension, which is characteristic of plant PCKs. The transcript level was much higher in the daytime than at night in 14-day old seedlings. However, in 42-day old plants the extent of diurnal change decreased. The maize PCK was expressed in Escherichia coli with the pET32 plasmid and purified to homogeneity. Through digestion with enterokinase, two types of enzyme were prepared; one with an intact N-terminus and the other lacking its N-terminal 77 amino acid residues due to over-digestion. The truncated protein had about 2-fold higher specific activity than the intact one, and was inhibited by 3-phosphoglycerate (3-PGA) with an I0.5 of 17.5 mM. In contrast, the intact protein was almost insensitive to 3-PGA. These results strongly suggest that the intact N-terminal extension may be involved in the regulation of PCK activity in vivo through some modification such as reversible phosphorylation.
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  • 98
    ISSN: 1573-5028
    Keywords: calcium-dependent protein kinase ; gene expression ; immunoassays ; light regulation ; rice ; seed development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We investigated the spatial and temporal expression patterns of two rice calcium-dependent protein kinases (CDPKs), OsCDPK2 and OSCDPK11, using isoform-specific antisera. Bands of the expected molecular sizes for OsCDPK2 (59 kDa) and OsCDPK11 (61 kDa) were detected on western blots. OsCDPK2 and OsCDPK11 mRNA and protein levels increased in unison during flower development. However, at the onset of seed development, the protein expression profiles diverged significantly. OsCDPK2 protein was expressed at low levels during early seed development, but increased to high levels that were maintained in later stages (20 days after fertilisation, DAF). Conversely, OsCDPK11 protein levels were high at the beginning of seed development, but fell rapidly from 10 DAF onwards. This decrease in the level of OsCDPK11 protein was associated with the abundant synthesis of a truncated mRNA species. OsCDPK2 expression was also closely associated with light perception. OsCDPK2 protein was barely detectable in green leaves exposed to light, but levels increased sharply when plants were shifted to darkness. Initially, this increase reflected a rapid elevation in the levels of OsCDPK2 mRNA, which was normally located in the mesophyll. Conversely, OsCDPK11 mRNA and protein levels were unaffected by light. These data strongly indicate that two rice CDPK isoforms have different functions in seed development and in response to light in leaves.
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  • 99
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    Euphytica 106 (1999), S. 117-123 
    ISSN: 1573-5060
    Keywords: differential display ; gene expression ; heterosis ; hybrid wheat ; seedling leaf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Differential display of mRNA was used to analyze the differences of gene expression in seedling leaves between heterotic hybrid/nonheterotic hybrid and their parental inbreds in order to study the molecular basis of heterosis in wheat. The results indicated that patterns of gene expression in hybrids differ significantly from their parents. Both quantitative and qualitative differences were observed. The quantitative differences include gene over-expression, gene under-expression in hybrid and dominant expression of highly-expressed parental genes in hybrids. The qualitative differences include silencing in hybrids of genes expressed either in male or female parent, and silencing in hybrids of genes expressed in both parents. Expression in hybrid of genes only expressed either in male or female parent was also observed. It was also found that some genes expressed at high level in heterotic hybrid were underexpressed or expressed at low level in nonheterotic hybrid. One differentially expressed cDNA fragment 4B was cloned and sequenced after being confirmed through Northern blot analysis. Homology search in GenBank proved that the cDNA fragment is a new sequence. The selection of primers for differential RNA display in wheat and the relationship between wheat heterosis and alteration of gene expression in hybrids as compared to their parental inbreds were also discussed.
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  • 100
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    Plant growth regulation 29 (1999), S. 47-76 
    ISSN: 1573-5087
    Keywords: cold ; chill ; freezing ; gene expression ; signal transduction pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Temperature is expected to affect all plant processes. Consistent with this, expression of a large number of specific mRNAs and proteins is up-regulated during cold-acclimation. Their possible functions are outlined, encompassing a wide range of processes, some possibly related to other winter stresses besides cold. Some of the cold-responsive sequences are associated with constitutive or stress-related metabolism, others are probably protective, some may influence freezing, and many are of as yet unknown function. While many of the sequences code for intracellular proteins, a significant number code for apoplastic proteins with a variety of possible functions. Transient influx of calcium into the cytosol appears to be a key step in the response to cold, and also to many other stresses and signals. Similarly, the cold-responsive promoter element identified so far is also responsive to drought and salt. However, how cold is sensed, and any cold-specific aspects of the cold signal transduction pathway, are, so far, unknown. What is clear is that, at least in the model plant Arabidopsis thaliana, cold-, desiccation-, salt- and ABA-triggered signal transduction pathways, and possibly others, run partly in parallel and partly intersect. This may be partly explained by a need for an integrated winter-response. The total number of genes which are cold-responsive and the quantity of resources which this implies are used in this way, indicate that many must have a positive role in acclimation. Experiments which modify membrane lipid unsaturation or solute accumulation, achieved by transformation of plants to express exotic or heterologous genes or by other means, confirm that these factors affect chill- or freezing-tolerance. A transgenic test has shown that one cold-up-regulated gene of previously unknown function contributes to freezing-tolerance, but the small effect re-emphasises the probably cumulative nature of the contributions of many cold-up-regulated sequences to acclimation. On the other hand, mutant analysis indicates some genes may make a comparatively larger contribution. Transformation of alfalfa to overexpress a superoxide dismutase gene increased cold-tolerance and drought-resistance and demonstrated that improvements in field-survival of stresses is possible by transgenic means. Over-expression of a transcription factor, CBF1, conferred freezing-tolerance on Arabidopsis, showing that manipulation of the signal transduction pathway could be an important method for modifying cold-tolerance.
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