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  • 2000-2004  (56)
  • 1990-1994  (4,805)
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  • Organic Chemistry  (6,983)
  • gene expression
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  • 1
    ISSN: 1569-8041
    Keywords: gene expression ; IRF-1 and IRF-2 ; p68 ; PKR ; signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background:Interferon regulatory factor 1 (IRF-1) has beendemonstrated to possess antiproliferative and tumor suppressor functions, onthe contrary, IRF-2 has been suggested to induce oncogenetic effect in somecell lines, but not evaluated in tumor patients. Patients and methods:In 35 carcinoid tumor patients, expressionsof IRF-1 and IRF-2 were investigated by immunohistochemistry and their valueswere analyzed with clinical treatment response. In carcinoid tumor cell line,Bon1, effects of IFN-α on the expression of both IRF-1 and IRF-2 mRNAs andproteins were determined by Northern blot, RNase protection assays and Westernblot analysis. Results:IFN-α up-regulated the expression of IRF-1 and IRF-2both in vivoand in vitro. In carcinoid tumors, IFN-αtreatment led to a significant increase in the expression of IRF-1 (P〈 0.001) and IRF-2 (P 〈 0.001). Moreover, the IRFs inductionwas correlated with the clinical response of IFN-α treatment, althoughtheir baseline values were not predictive. In addition, expressions of IRF-1and IRF-2 were significantly correlated with the p68kinaseexpression (P = 0.032 and P = 0.0176, respectively) and theexpression of IRF-1 protein was positively correlated with that of IRF-2(r = 0.671,P = 0.0001) tested in the same specimens. Conclusions:IRF-1 as well as IRF-2 have therapeutic implicationsin carcinoid tumors during treatment with interferon-α and IRFs inductionmight be used as indicators of response to treatment with interferon-α.
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  • 2
    ISSN: 1570-0267
    Keywords: cDNA ; PCR cDNA ; TaqMan Analysis ; gene expression ; Pearson's correlation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Comparative gene expression studies are often limited by low availability of tissue and poor quality of extractable mRNA. Collective PCR amplification of minute quantities of mRNA has great potential for overcoming these limitations. However, there remains significant concern about the effects of amplification on the absolute and relative abundance of individual mRNAs that could complicate subsequent gene expression studies. To address this problem, we systematically compared the relative abundance of many specific mRNAs from complex cDNA preparations (from tissue and cultured cells) both before and after amplification by PCR. Our results demonstrated that, as expected, the absolute abundance of different mRNAs in a cDNA library is altered in an unpredictable manner by PCR amplification. However, we found that the concentration ratios of specific mRNAs among different cDNA preparations were routinely well conserved after PCR amplification. Thus, for the purpose of comparative expression studies for specific mRNAs in two (or more) complex cDNAs, PCR-amplified cDNA is equally useful as unamplified cDNA. These results provide a rigorous experimental validation and offer a theoretical treatment to support the utility of PCR amplified cDNA for differential gene expression studies. We conclude that the inherent difficulties in performing differential screening studies such as gene chip and array analyses on limited amounts of biological materials can be overcome by a PCR amplification step without compromising data quality.
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  • 3
    ISSN: 1573-4919
    Keywords: myosin heavy chain ; gene expression ; hypertrophy ; dexamethasone ; promoter function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Cardiac hypertrophy has been observed in newborn infants treated with dexamethasone (DEX). This study was undertaken to examine whether DEX-induced hypertrophy in newborn rats is associated with redistribution of cardiac myosin heavy chain (MHC) isoforms and if so, the effects involve transcriptional regulation. Newborn rats were injected with either DEX (1 mg/kg/day; s.c.) or equivalent volume normal saline for 1, 3, 5, 7 or 9 days. Hypertrophy was quantified by heart dry/wet wt ratios, heart/body wt ratios, and total protein content of the myocardium. Changes in the expression of cardiac MHC mRNA were characterized by northern blot and slot blot analyses, using isoform specific probes for a- and β-MHC genes. DEX effect on α-MHC gene transcription was analyzed by transiently transfecting various α-MHC promoter/CAT reporter constructs into primary cultures of cardiac myocytes derived from one day old rat pups. DEX administration into newborn rats produced significant cardiac hypertrophy ranging from 23% at day 1 to 59% at 9 days. The hypertrophy was accompanied by immediate increase (83%) in steady state level of the α-MHC mRNA within one day and a maximum increase (148%) at 7 days of treatment. The steady state level of β-MHC mRNA declined by 25% at day 1 and a maximum decrease of 54% at day 7 of DEX treatment. The changes in MHC mRNA were also reflected in their protein levels as determined by V1 and V3 isozyme analysis. DEX treatment of primary cultures of cardiomyocytes following transfection with a-MHC promoter/CAT reporter constructs resulted in increased CAT expression in a dose dependent manner. The minimum α-MHC gene sequences responding to DEX treatment were located between the -200 to -74-bp region of the gene, resulting in 2-fold and 6-fold activation of CAT reporter after 0.05 and 0.1 mM doses of DEX, respectively. Our data indicate that DEX induced cardiac hypertrophy in newborn rats is accompanied by increased expression of α-MHC and decreased expression of β-MHC. The α-MHC effects are mediated in part through transcriptional mechanisms.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 212 (2000), S. 5-9 
    ISSN: 1573-4919
    Keywords: transcriptional regulation ; gene expression ; coactivator ; repressor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The CREB-CREM transcription factors are the main gene regulatory effectors of the cAMP signaling pathway. The investigations of this family of transcription factors had a profound impact on the understanding of signaling-induced gene transcription. Here we discuss some key aspects of the underlying biology, review transcriptional activation by CREB proteins through transcription cofactors and present novel insights into the context- and position-specific function of CREB on complex genes.
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  • 5
    ISSN: 1573-4919
    Keywords: AP-1 ; cobalt chloride ; gene expression ; heme oxygenase ; oxidative stress ; sodium arsenite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Previously, chick heme oxygenase-1 (cHO-1) gene was cloned by us and two regions important for induction by sodium arsenite were identified. These two regions were found to contain consensus sequences of an AP-1 (-1580 to -1573) and a MRE/cMyc complex (-52 to -41). In the current study, the roles of these two elements in mediating the sodium arsenite or cobalt chloride dependent induction of cHO-1 were investigated further. DNA binding studies and site-directed mutagenesis studies indicated that both the AP-1 and MRE/cMyc elements are important for the sodium arsenite induction, while cobalt chloride induction involves only the AP-1 element. Electrophoretic mobility shift assays showed that nuclear proteins binding to the AP-1 element was increased by both sodium arsenite or cobalt chloride treatment, whereas the binding of proteins to the MRE/cMyc element showed a high basal expression in untreated cells and the binding activity was only slightly increased by sodium arsenite treatment. Site-directed mutagenesis studies showed that, to completely abolish sodium arsenite induction, both the AP-1 and MRE/cMyc elements must be mutated; mutation of either element alone resulted in only a partial effect. In contrast, a single mutation at AP-1 element was sufficient to reduce the cobalt chloride induction almost completely. The MRE/cMyc complex plays a major role in the basal level expression, and shares some similarities to the upstream stimulatory factor element (USF) identified in the promoter regions of mammalian HO-1 genes and other stress regulated genes. Because sodium arsenite is known to cause oxidative stress and because activation of AP-1 proteins has been shown to be a key step in the oxidative stress response pathway, we also explored the possibility that the induction of the cHO-1 gene by sodium arsenite is mediated through oxidative stress pathway(s) by activation of AP-1 proteins. We found that pretreatment with antioxidants (N-acetyl cysteine or quercetin) reduced the induction of the endogenous cHO-1 message or cHO-1 reporter construct activities induced by sodium arsenite or cobalt chloride. These antioxidants also reduced the protein binding activities to the AP-1 element in the electrophoretic mobility shift assays. In summary, induction of the cHO-1 gene by sodium arsenite or cobalt chloride is mediated by activation of the AP-1 element located at -1,573 to -1,580 of the 5′ UTR.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 205 (2000), S. 1-11 
    ISSN: 1573-4919
    Keywords: kidney ; ischemia-reperfusion injury ; free radicals ; reactive oxygen species ; gene expression ; antioxidant enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Reactive oxygen species (ROS; O2-, H2O2, and OH·), normal by-products of cellular metabolic processes, are kept in control by antioxidant enzymes, such as catalase, glutathione peroxidase (GPX) and superoxide dismutases (SODs). To understand the role of antioxidant enzymatic defenses against ROS injury following ischemia-reperfusion, we examined the effect on kidney exposed to varying periods (30, 60 or 90 min) of ischemia followed by different periods of reperfusion. The enzymatic activities and protein levels of catalase, GPX, CuZnSOD and MnSOD were relatively unaffected at 30 min of ischemia followed by 0, 2 or 24 h reperfusion. However, 60 or 90 min of ischemia followed by 0, 2 or 24 h of reperfusion resulted in a decrease in activities and protein levels which paralleled the duration of ischemic injury. MnSOD activity tended to recover towards normal during reperfusion. Examination of the mRNA levels of these antioxidant enzymes demonstrated a severe decrease in mRNA levels of catalase and GPX at a time point of minimal ischemic injury (30 min of ischemia followed by reperfusion) suggesting that loss of mRNA of catalase and GPX may be the first markers of alterations in cellular redox in ischemia-reperfusion injury. Greater loss of mRNA for catalase, GPX and CuZnSOD were observed following longer periods (60 or 90 min) of ischemia. The mRNA for MnSOD was upregulated at all time points of ischemia-reperfusion injury. Actually, the greater decrease in mRNAs for catalase, GPX and CuZnSOD in the acute phase (within 24 h) subsequently showed a further decrease in these enzyme activities in the subacute phase (72 or 120 h after ischemia). These enzyme activities in the 30 min ischemia group, but not in the 90 min group, already showed tendencies for normalization at 120 h after ischemia. To understand the molecular basis of the loss of mRNA of these antioxidant enzymes during ischemia-reperfusion injury, we examined the rate of transcription by nuclear run-on assays. The similar rates of transcription in control and kidney exposed to ischemia-reperfusion indicates that the loss of mRNA for catalase, GPX and CuZnSOD are possibly due to the increased rate of turnover of their mRNAs. These studies suggest that expression of antioxidant genes during ischemia-reperfusion are not coordinately expressed and the differential loss of antioxidant enzymes may be the contributing factor(s) towards the heterogeneous renal tissue damage as a result of ischemia-reperfusion induced oxidative stress.
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  • 7
    ISSN: 1573-4919
    Keywords: prostaglandin ; cyclooxygenase ; transcriptional regulation ; gene expression ; promotor activation ; transcription ; endothelial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Interleukin-1β (IL-1) is a potent inducer of cyclooxygenase-2 (COX-2) and prostaglandin biosynthesis in many types of cells, yet little is known about the molecular mechanisms regulating IL-1 mediated prostanoid biosynthesis in the endothelium of the microvasculature. Therefore, we examined the cis- and trans-acting factors regulating IL-1-induced COX-2 expression in the human microvascular endothelial cell line, HMEC-1. IL-1 enhanced steady state levels of COX-2 protein and mRNA synthesis by ≈ 2-fold which preceded a 2-fold increase in PGFα biosynthesis. Expression of a series of COX-2 promoter-luciferase constructs in IL-1 treated HMEC-1 cells revealed that the 'full length' (-1432/+59 bp) promoter was 10 times more active than the SV-40 promoter/enhancer and that it could be further activated by IL-1. Surprisingly however, all except for the shortest COX-2 promoter construct retained the ability to respond to IL-1 and luciferase activity driven by -191/+59 bp COX-2 promoter was as responsive to IL-1 as the full-length promoter. Moreover, site-directed promoter mutagenesis and electophoretic mobility shift assays (EMSA) indicate that the combinatorial actions of AP2, NF-IL6, and CRE elements are critical for both constitutive and IL-1-inducible COX-2 promoter activity. Understanding the mechanism(s) regulating COX-2 gene expression and prostaglandin biosynthesis in the microvasculature has important implications with regard to inflammation and angiogenesis in vivo.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 203 (2000), S. 163-167 
    ISSN: 1573-4919
    Keywords: thymosin β-4 ; gene expression ; chloramphenicol acetyltransferase ; NIH3T3 cells ; interferon response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Expression of the gene coding for thymosin β-4 (Tβ-4), the major G-actin sequestering peptide in the cell, is regulated mainly at the level of transcription. In this study, we examined the nucleotide sequence of the 5′-flanking region (from - 2202 to - 881) of the mouse Tβ-4 gene, and demonstrated that the DNA fragment from -278 to +410 of this gene was capable of directing the expression of a chloramphenicol acetyltransferase reporter gene in NIH3T3 cells. However, expression of the reporter gene in cells cannot be induced by interferon-a treatment even though a rapid activation of endogenous Tβ-4 gene by this cytokine was observed. These results suggest that the projected interferon-stimulated response element (ISRE) might reside in other parts of the mouse Tβ-4 gene.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 211 (2000), S. 103-110 
    ISSN: 1573-4919
    Keywords: thioacetamide ; glutathione-S-transferase ; rat liver ; transcription ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of thioacetamide (TA), an hepatotoxic and hepatocarcinogenic compound, on the expression and activity of the cytosolic enzyme glutathione-S-transferase (GST) was studied in rat liver. Four h following the administration of 14C-labeled thioacetamide (10 mg/Kg), several subunits of GST were found to be radioactively labeled. A single sublethal dose of TA (250 mg/Kg) decreased by three-fold the expression of classα GST at 24-48 h of treatment, but did not significantly affect the transcription of class μ GST. The activity of the enzyme toward 1-chloro-2,4-dinitrobenzene was mildly inhibited (66% of the control) by a 24 h TA treatment and gradually increased thereafter. It is proposed that the covalent binding of TA or its derivative to the GST subunits does not affect the activity of the enzyme. Nevertheless, GST activity inhibition is due to the deleterious effect of TA on GST transcription.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 209 (2000), S. 125-129 
    ISSN: 1573-4919
    Keywords: apolipoprotein E ; apolipoprotein A-I ; gene expression ; transgenic mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The levels of plasma apolipoprotein (apo) E, an anti-atherogenic protein involved in mammalian cholesterol transport, were found to be 2-3 fold lower in mice over-expressing human apoA-I gene. ApoE is mainly associated with VLDL and HDL-size particles, but in mice the majority of the apoE is associated with the HDL particles. Over-expression of the human apoA-I in mice increases the levels of human apoA-I-rich HDL particles by displacing mouse apoA-I from HDL. This results in lowering of plasma levels of mouse apoA-I. Since plasma levels of apoE also decreased in the apoA-I transgenic mice, the mechanism of apoE lowering was investigated. Although plasma levels of apoE decreased by 2-3 fold, apoB levels remained unchanged. As expected, the plasma levels of human apoA-I were almost 5-fold higher in the apoAI-Tg mice compared to mouse apoA-I in WT mice. If the over-expression of human apoA-I caused displacement of apoE from the HDL, the levels of hepatic apoE mRNA should remain the same in WT and the apoAI-Tg mice. However, the measurements of apoE mRNA in the liver showed 3-fold decreases of apoE mRNA in apoAI-Tg mice as compared to WT mice, suggesting that the decreased apoE mRNA expression, but not the displacement of the apoE from HDL, resulted in the lowering of plasma apoE in apoAI-Tg mice. As expected, the levels of hepatic apoA-I mRNA (transgene) were 5-fold higher in the apoAI-Tg mice. ApoE synthesis measured in hepatocytes also showed lower synthesis of apoE in the apoAI-Tg mice. These studies suggest that the integration of human apoA-I transgene in mouse genome occurred at a site that affected apoE gene expression. Identification of this locus may provide further understanding of the apoE gene expression.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 212 (2000), S. 29-34 
    ISSN: 1573-4919
    Keywords: cAMP ; transcription factor-decoy oligonucleotides ; CRE ; Ap-1 ; p53 ; tumor growth ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Nucleic acid molecules with high affinities for a target transcription factor can be introduced into cells as decoy cis-elements to bind these factors and alter gene expression. This review discusses a synthetic single-stranded palindromic oligonucleotide, which self-hybridizes to form a duplex/hairpin and competes with cAMP response element (CRE) enhancers for binding transcription factors. This oligonucleotide inhibits CRE- and Ap-1-directed gene transcription and promotes growth inhibition in vitro and in vivo in a broad spectrum of cancer cells, without adversely affecting normal cell growth. Evidence presented here suggests that the CRE-decoy oligonucleotide can provide a powerful new means of combating cancers, viral diseases, and other pathological conditions by regulating the expression of cAMP-responsive genes.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 212 (2000), S. 73-79 
    ISSN: 1573-4919
    Keywords: adrenergic receptors ; renin-angiotensin system (RAS) ; gene expression ; kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract To investigate the molecular mechanism(s) of action of catecholamines on the expression of the angiotensinogen (ANG) gene in kidney proximal tubular cells, we used opossum kidney (OK) cells with a fusion gene containing the 5′-flanking regulatory sequence of the rat ANG gene fused with a human growth hormone (hGH) gene as a reporter, pOGH (rANG N-1498/+18), permanently integrated into their genomes. The level of expression of the ANG-GH fusion gene was quantified by the amount of immunoreactive-hGH (IR-hGH) secreted into the medium. The addition of norepinephrine (NE), isoproterenol (a β1/β2-adrenergic receptor (AR) agonist) and iodoclonidine (an α2-AR agonist) stimulated the expression of the ANG-GH fusion gene in a dose-dependent manner, whereas the addition of epinephrine and phenylephrine (α1-AR agonist) had no effect. The stimulatory effect of NE was blocked by the presence of propranolol (β-AR blocker), atenolol (β1-AR blocker), yohimbine (α2-AR blocker), Rp-cAMP (an inhibitor of cAMP-dependent protein kinase AI & AII) and staurosporine (an inhibitor of protein kinase C), but was not blocked by ICI 118, 551 (β2-AR blocker) and prazosin (α1-AR blocker). The addition of a combination of isoproterenol and iodoclonidine or a combination of 8-Bromo-cAMP (8-Br-cAMP) and phorbol 12-myristate (PMA) synergistically stimulated the expression of the ANG-GH fusion gene as compared to the addition of isoproterenol, iodoclonidine, 8-Br-cAMP or PMA alone. Furthermore, the addition of NE, 8-Br-cAMP or PMA stimulated the expression of pOGH (rANG N-806/-779/-53/+18), a fusion gene containing the putative cAMP responsive element (CRE, ANG N-806/-779) upstream of the ANG promoter (ANG N-53/+18) in OK cells, but had no effect on the expression of fusion genes containing the mutant of the CRE. Gel mobility shift assays revealed that the ANG-CRE binds with the DNA-binding domain (bZIP 254-327) of the cAMP-responsive binding protein (CREB). The binding of the labeled ANG-CRE to CREB (bZIP254-327) was displaced by unlabeled ANG-CRE and the CRE of the somatostatin gene but not by the mutants of the ANG-CRE. Finally, NE stimulated the phosphorylation of CREB in OK cells. These studies demonstrate that the molecular mechanism(s) of NE action on the expression of the ANG gene in OK cells may be mediated via both the PKA and PKC signalling pathways and via the phosphorylation of CREB. The phosphorylated CREB then interacts with the CRE in the 5′-flanking region of the ANG gene and subsequently stimulates the gene expression.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 212 (2000), S. 135-142 
    ISSN: 1573-4919
    Keywords: gene expression ; catecholamines ; angiotensin II ; heart failure ; myosin ; hypertension ; eprosartan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Pressure overload of the heart is associated with a perturbed gene expression of the cardiomyocyte leading to an impaired pump function. The ensuing neuro-endocrine activation results in disordered influences of angiotensin II and catecholamines on gene expression. To assess whether angiotensin II type 1 receptor inhibition can also counteract a raised sympathetic nervous system activity, spontaneously hypertensive rats fed a hypercaloric diet were treated with eprosartan (daily 90 mg/kg body wt) and cardiovascular parameters were monitored with implanted radiotelemetry pressure transducers. Both, blood pressure and heart rate were increased (p 〈 0.05) by the hypercaloric diet. Although eprosartan reduced (p 〈 0.05) the raised systolic and diastolic blood pressure, the diet-induced rise in heart rate was blunted only partially. In addition to drugs interfering with the enhanced catecholamine influence, compounds should be considered that selectively affect cardiomyocyte gene expression via 'metabolic' signals.
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  • 14
    ISSN: 1573-4919
    Keywords: angiotensinogen ; fibronectin ; gene expression ; transcriptional regulation ; cardiomyocytes ; vascular smooth muscle cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Angiotensinogen (AGT) is a unique substrate of the renin-angiotensin system and fibronectin (FN) is an important component of the extracellular matrix. These play critical roles in the pathophysiological changes including cardiovascular remodeling and hypertrophy in response to hypertension. This study was performed to examine the regulation of AGT and FN gene in cardiac myocytes (CMs) and vascular smooth muscle cells (VSMCs) in response to mechanical stretch. Mechanical stretch significantly increased the AGT mRNA expression in CMs, while these stimuli did not affect FN mRNA levels. On the other hand, Mechanical stretch upregulated FN mRNA levels in VSMCs, whereas no increase in AGT mRNA levels was observed in response to stretch stimuli. An angiotensin II type 1 (AT1) receptor antagonist (CV11974) significantly decreased these stretch-mediated increases in mRNA level and promoter activity of the AGT and FN gene, whereas angiotensin II type 2 (AT2) receptor antagonist (PD123319) did not affect the induction. These results indicate that mechanical stretch activates transcription of the AGT and FN gene mainly via AT1 receptor-pathway in CMs and VSMCs. Furthermore, mechanisms regulating AGT and FN gene seem to be different between CMs and VSMCs.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 212 (2000), S. 211-217 
    ISSN: 1573-4919
    Keywords: angiotensin receptor ; medullary thick ascending limb ; sodium intake ; primary cell culture ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Angiotensin II (Ang II) is an important regulator of the function of medullary thick ascending limb of loop of Henle (MTAL). Recent studies showed that changes in Ang II receptor expression occur and underlie changes in the function of proximal tubules during altered sodium intake. The present experiment was designed to determine (1) whether expression of the type 1 Ang II (AT1) receptor in the MTAL is regulated by altered sodium intake, and (2) the specific pathway(s) mediating sodium-induced AT1 expression in the MTAL. Wistar rats were fed a normal sodium (0.5%, NS), low sodium (0.07%, LS), or high sodium (4%, HS) diet for 2 weeks. Northern blot analysis and radioligand binding showed that in rats fed a normal sodium diet the rank of order for both AT1 mRNA expression and receptor density was outer medulla 〉 cortex 〉 inner medulla. Sodium restriction significantly increased both AT1 mRNA expression and receptor density in the outer medulla. In contrast, neither AT1 mRNA expression nor receptor density in the outer medulla was altered by sodium loading. Losartan treatment (3 mg/kg/per day by oral gavage for 2 weeks) prevented low sodium-induced upregulation of the AT1 receptor in the outer medulla, but it had no effect on AT1 expression in the outer medulla of rats fed a normal sodium diet. Highly purified suspensions of MTAL were isolated from rats fed a normal or low sodium diet. Low sodium intake significantly increased AT1 mRNA level by 184% and AT1 receptor density by 58% in MTALs. Primary cultures of MTAL cells were treated with PBS, Ang II (10-8 M), and Ang II + 17 octadecynoic (17 ODYA, 10 μM). Ang II caused about 2-fold increase in AT1 mRNA levels, and this increase was diminished by about 30% by the addition of 17 ODYA. We conclude that (1) sodium restriction but not sodium loading increases AT1 receptor expression in the MTAL, (2) low sodium-induced upregulation of the AT1 receptor in the MTAL is Ang II-dependent, and (3) Ang II-induced upregulation of the AT1 receptor in the MTAL is mediated, at least in part, by cytochrome P450 pathways.
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  • 16
    ISSN: 1573-4919
    Keywords: renin angiotensin system ; sarcoplasmic reticulum ; Ca2+-handling ; gene expression ; ischemia-reperfusion ; cardioprotection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The aim of this study was to explore the possible participation of cardiac renin-angiotensin system (RAS) in the ischemia-reperfusion induced changes in heart function as well as Ca2+-handling activities and gene expression of cardiac sarcoplasmic reticulum (SR) proteins. The isolated rat hearts, treated for 10 min without and with 30 μM captopril or 100 μM losartan, were subjected to 30 min ischemia followed by reperfusion for 60 min and processed for the measurement of SR function and gene expression. Attenuated recovery of the left ventricular developed pressure (LVDP) upon reperfusion of the ischemic heart was accompanied by a marked reduction in SR Ca2+-pump ATPase, Ca2+-uptake and Ca2+-release activities. Northern blot analysis revealed that mRNA levels for SR Ca2+-handling proteins such as Ca2+-pump ATPase (SERCA2a), ryanodine receptor, calsequestrin and phospholamban were decreased in the ischemia-reperfused heart as compared with the non-ischemic control. Treatment with captopril improved the recovery of LVDP as well as SR Ca2+-pump ATPase and Ca2+-uptake activities in the postischemic hearts but had no effect on changes in Ca2+-release activity due to ischemic-reperfusion. Losartan neither affected the changes in contractile function nor modified alterations in SR Ca2+-handling activities. The ischemia-reperfusion induced decrease in mRNA levels for SR Ca2+-handling proteins were not affected by treatment with captopril or losartan. The results suggest that the improvement of cardiac function in the ischemic-reperfused heart by captopril is associated with the preservation of SR Ca2+-pump activities; however, it is unlikely that this action of captopril is mediated through the modification of cardiac RAS. Furthermore, cardiac RAS does not appear to contribute towards the ischemia-reperfusion induced changes in gene expression for SR Ca2+-handling proteins.
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  • 17
    ISSN: 1573-4919
    Keywords: pressure overload ; gene expression ; subcellular remodeling ; sarcoplasmic reticulum Ca2+-handling ; anti-hypertensive therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effects of propranolol and verapamil on contractile dysfunction, subcellular remodeling and changes in gene expression in cardiac hypertrophy due to pressure overload were examined. Rats were subjected to banding of the abdominal aorta and then treated with either propranolol (10 mg/kg daily), verapamil (5 mg/kg daily) or vehicle for 8 weeks after the surgery. Depression of the left ventricular function in the hypertrophied heart was associated with decreases in myofibrillar and myosin CA2+ ATPase activities as well as Ca2+-pump and Ca2+-release activities of the sarcoplasmic reticulum (SR). The level of a-myosin heavy chain (α-MHC) mRNA was decreased while that of β-MHC mRNA was increased in the pressure-overloaded heart. The level of SR Ca2+-pump ATPase (SERCA2) mRNA and protein content for SERCA2 were decreased in the pressure overloaded heart. Treatment of the hypertrophied animals with propranolol or verapamil resulted in preservation of the left ventricular function and prevention of the subcellular alterations. Shift in the α- and β-MHC mRNA levels and changes in the expression in SERCA2 mRNA level and protein content were also attenuated by these treatments. The results suggest that blockade of β-adrenoceptors or voltage-dependent calcium channels normalizes the cardiac gene expression, prevents subcellular remodeling and thus attenuates heart dysfunction in rats with cardiac hypertrophy. Furthermore, both cardiac β-adrenoceptors and L-type Ca2+-channels may be involved in the genesis of cardiac hypertrophy due to pressure overload.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 213 (2000), S. 119-126 
    ISSN: 1573-4919
    Keywords: TIS11 ; an immediate early gene ; gene cloning ; gene expression ; gene organization ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The TIS11 gene is an immediate early gene that is induced rapidly and transiently by phorbol 12-myristate 13-acetate and various growth factors. To study transcriptional regulation of the gene, a genomic clone of rat TIS11 was isolated, and the organization of exon-intron structure and transcriptional initiation site were determined. The rat TIS11 gene consisted of 2 exons spanning approximately 2.5 kb. Several canonical sequences for binding of transcriptional factors were found in the 5′-flanking region. The 5.3 kb of the 5′-flanking region fused to a luciferase reporter gene showed promoter activity when introduced into rat pheochromocytoma PC12 cells. Analyses with serial 5′-deletion mutants suggested that the major positive regulatory region is located at the region of -241 to -76, and that the minimum promoter region is within the 76-bp upstream of the transcriptional initiation site. Gel mobility shift assays revealed that PC12 cell nuclear proteins specifically bind to the major positive regulatory region of the TIS11 gene. The identified nuclear protein components may act as the positive trans-acting factors in the basal expression of the TIS11 gene in PC12 cells.
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  • 19
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; plant development ; antioxidant genes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The expression of antioxidant genes has been analyzed in a potato plant and during tuber dormancy. Manganese superoxide dismutase (MnSOD), cytosolic copper and zinc superoide dismutase (Cu/ZnSOD), catalase class II, cytosolic ascorbate peroxidase (APX) and glutathione peroxidase (GPX) are expressed at the RNA level in all the contexts analyzed. By contrast, the expression of the iron superoxide dismutase (FeSOD) and plastidic Cu/ZnSOD seems to be limited to green tissues, as shown by northern blots and native gels. A complex DAB-peroxidase isozyme pattern (using diaminobenzidine as substrate) has been observed in different developmental contexts analyzed, but hardly observed in tubers. During tuber dormancy, MnSOD and cytosolic Cu/ZnSOD activity was relatively constant in both Désirée and Bintje varieties while catalase activity decreases. Moreover, tuber dormancy breakage did not involve significant changes in the activity of these enzymes. On the basis of these results, the possible link between active oxygen species (AOS) metabolism and dormancy is discussed.
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  • 20
    ISSN: 1871-4528
    Keywords: gene expression ; cDNA-AFLP ; RNA-fingerprinting ; organogenesis ; tuberisation ; dormancy ; sprouting ; cluster analysis ; metabolic pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato tuber life-cycle is composed of many individual developmental stages including tuber formation, tuber development, dormancy and sprouting. We have used cDNA-AFLP fingerprinting to analyse gene expression in 24 individual stages of development, over the period from stolon formation through sprouting. In addition to these developmental stages, different tissues were analysed to assess tissue specificity and various controls were incorporated to determine process specificity. In total around 18000 transcript derived cDNA fragments (TDFs) were visualised from which circa 2600 were included in a statistical analysis allowing general conclusions about gene expression during development. More than 200 process specific TDFs were isolated and sequenced throughout the potato tuber life-cycle. The sequence similarities of these TDFs to known genes give an insight into the kinds of processes occurring during tuberisation, dormancy and sprouting.
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  • 21
    ISSN: 1573-6768
    Keywords: aging ; Cu, Zn superoxide dismutase ; Drosophila melanogaster ; gene expression ; wingless
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the oxidative stress hypothesis of aging therandom accumulation of oxidative damage over time ispostulated to cause aging. The pace at whichoxidative damage accrues determines the rate of aging,but it is less clear how the accumulation of randomdamage could cause the stereotypic pattern of aging. It has been proposed that oxidative damage induceschanges in gene expression, translating a random inputof damage into a patterned output. In support of thiswe show that in adult Drosophila melanogaster,with a deficiency in the anti-oxidant enzyme Cu, Znsuperoxide dismutase (Sod), an increase in oxidativestress, and a shortened life span, there isacceleration in the normal age-related temporalpattern of wingless gene expression. Theacceleration in the temporal pattern of winglessgene expression is proportional to the shortened lifespan suggesting that the shortened life span of Soddeficient animals is due, not to an abnormalpathological process, but to an increase in the rateof aging.
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  • 22
    ISSN: 1573-5028
    Keywords: gene expression ; germination ; NADPH-cytochrome P450 reductase ; Pseudotsuga menziesii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract NADH-cytochrome P450 is a key enzyme that transfers electrons from NADPH to the cytochrome P450 family of enzymes. To begin to determine the regulation of CPR gene expression and enzyme activity in Douglas-fir a full-length cDNA was isolated from a seedling λZAP cDNA library and the ORF was used to develop a synthetic CPR-peptide-based antiserum. Northern blot analysis indicated CPR expression was regulated both developmentally prior to seed maturation and during germination, and differentially in the cotyledons, radicle and megagametophyte of seed and seedling tissues. The CPR-peptide antiserum detected a single CPR in seed and seedling microsomes analyzed by western blot of two-dimensional SDS-polyacrylamide gels. In microsomal extracts from whole seeds and seedlings, the amount of CPR protein remained constant while NADPH:cytochrome c reductase activity increased during stratification, germination and early seedling development. In contrast to cotyledons and megagametophyte, the level of CPR protein detected in radicles was higher than expected when compared to the amount of CPR transcript.
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  • 23
    ISSN: 1573-5036
    Keywords: ammonium ; birch ; gene expression ; nia promoter ; nitrate ; nitrate reductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A 1535 bp promoter of the nitrate reductase gene (nia) from birch (Betula pendula) and a series of 5′ deletions were fused to the β-glucuronidase (GUS) gene and introduced into Nicotiana plumbaginifolia. In transgenic plants the NR promoter sequences directed strong GUS expression in the root epidermal hair cells, and in phloem cells of leaf and stem vascular tissue. The NR promoter confers also a significant stimulation of the GUS gene expression by nitrate. These findings might indicate that nitrate flow is one of the signals involved into tissue and cell specific expression of the NR promoter GUS fusions.
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  • 24
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    Plant and soil 226 (2000), S. 219-225 
    ISSN: 1573-5036
    Keywords: arbuscular mycorrhizas ; gene expression ; Glomus mosseae ; nutrient transport processes ; plasma membrane H+-ATPases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The activity of H+-ATPases of plant and fungi generates an electrochemical gradient of H+ across the cell plasma membrane that drives a number of secondary transport systems, including those responsible for the translocation of cations, anions, amino acids and sugars. During the last years, several studies have been aimed at elucidating the role of plasma membrane H+-ATPases in the nutrient exchange processes taking place between the plant and the fungus in arbuscular mycorrhizal (AM) symbiosis. This paper reviews present knowledge about plasma membrane H+-ATPases and experimental evidence supporting the involvement of H+-ATPases of both organisms in the bidirectional transport of nutrients between partners. Molecular strategies that will provide further information on the function and regulation of plasma membrane H+-ATPases in AM symbiosis are presented and discussed.
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  • 25
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    Plant growth regulation 32 (2000), S. 27-39 
    ISSN: 1573-5087
    Keywords: ethylene ; gene expression ; jasmonic acid ; reactive oxygen species ; salicylic acid ; ultraviolet-B radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Depletion of the stratospheric ozone layer is leadingto an increase in ultraviolet-B (UV-B: 280–320 nm)radiation reaching the earth's surface. This hasraised interest in the possible consequence ofincreased UV-B levels on plant growth and developmentand the mechanisms underlying these responses. Although the effects of UV-B are now wellcharacterised at the physiological level, little isknown about the cellular and molecular mechanismsinvolved. Recent studies have shown that UV-B affectsa number of important physiological processes, such asphotosynthesis, through effects on gene expression. In addition, induction of a number of defensemechanisms, such as production of UV-B screeningpigments, increase in antioxidant enzymes andinduction of pathogenesis-related proteins, are alsomediated at the level of gene expression. The signaltransduction pathways by which UV-B regulates geneexpression are at present poorly understood. Thestudies carried out to date have, however, indicateda pivotal role for reactive oxygen species as keysecond messengers acting up-stream of a number ofpathways involving the plant hormones salicylic acid,jasmonic acid and ethylene. The transduction pathwaysidentified to date and the role of intermediates inregulating tolerance to UV-B damage are discussed inthis review.
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  • 26
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    Plant growth regulation 31 (2000), S. 35-42 
    ISSN: 1573-5087
    Keywords: β-1,4-endoglucanase ; ethylene ; fruit ; gene expression ; polygalacturonase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fruitlet abscission during fruit development is due to the activation ofpre-differentiated abscission zones (AZs) located between twig andpedicel, and/or pedicel and pericarp. Major advances on biochemicaland molecular aspects are related to β-1,4-endoglucanase (EG) andpolygalacturonase (PG), two cell hydrolases involved in the cell walldisassemblement responsible for fruit shedding. AZ activation isaccompanied by an increase in activity and transcript accumulation ofone or both enzymes. Expression of PG genes specifically related toabscission has been found in tomato flower AZ. In peach, an EG genehighly expressed in leaf and fruitlet AZs has been isolated. AZactivation is preceded by an induction of ethylene biosynthesis,paralleled by a stimulation of ACO activity and transcript accumulation.Ethylene, besides a dramatic stimulation of PG and EG, up or downregulates several other abscission related genes. The specificexpression of genes encoding for ethylene receptors in the AZ wouldsupport the hypothesis that fruitlet AZ specificity may depend on theability of this region to sense ethylene.
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  • 27
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; β-glucuronidase (GUS) reporter gene ; gene expression ; isoprenoids ; mevalonate kinase ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mevalonate kinase (MVK), the enzyme that catalyzes the phosphorylation of mevalonate to produce mevalonate 5-phosphate, is considered as a potential regulatory enzyme of the isoprenoid biosynthetic pathway. The Arabidopsis thaliana MVK gene corresponding to the MVK cDNA previously isolated has been cloned and characterized. RNAse protection analysis indicated that the expression of the MVK gene generates three mRNA populations with 5′ ends mapping 203, 254 and 355 nt upstream of the MVK ATG start codon. Northern blot analysis showed that the MVK mRNA accumulates preferentially in roots and inflorescences. Histochemical analysis, with transgenic A. thaliana plants containing a translational fusion of a 1.8 kb fragment of the 5′ region of the MVK gene to the β-glucuronidase (GUS) reporter gene, indicated that the MVK 5′-flanking region directs widespread expression of the GUS gene throughout development, although the highest levels of GUS activity are detected in roots (meristematic region) and flowers (sepals, petals, anthers, style and stigmatic papillae). The expression pattern of the MVK gene suggests that the role of the encoded MVK is the production of a general pool of mevalonate-5-phosphate for the synthesis of different classes of isoprenoids involved in both basic and specialized plant cell functions. Functional promoter deletion analysis in transfected A. thaliana protoplasts indicated that regulatory elements between positions −295 and −194 of the MVK 5′-flanking region are crucial for high-level MVK gene expression.
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  • 28
    ISSN: 1573-5028
    Keywords: gene expression ; hypersensitive responses ; plant defense responses ; salicylic acid ; tobacco mosaic virus ; WRKY DNA-binding proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A pathogen- and salicylic acid (SA)-induced DNA-binding activity has been recently identified in tobacco that is related to a previously identified class of WRKY DNA-binding proteins. To identify members of the WRKY gene family associated with this DNA-binding activity, we have attempted to isolate those WRKY genes that are induced by pathogen infection. Using a domain-specific differential display procedure, we have isolated two tobacco WRKY genes, tWRKY3 and tWRKY4, that are rapidly induced in resistant tobacco plants after infection by tobacco mosaic virus (TMV). Both tWRK3 and tWRKY4 encode proteins with a single WRKY domain that contain the conserved WRKYGQK sequence. Unlike other isolated WRKY proteins that contain the Cys2His2 zinc motif, tWRKY3 and tWRKY4 appear to contain the Cys2HisCys zinc motif. Nonetheless, both tWRKY3 and tWRKY4 are capable of binding DNA molecules with the W-box (TTGAC) element recognized by other WRKY proteins. Expression of the tWRKY3 and tWRKY4 genes could be rapidly induced not only by TMV infection but also by SA or its biologically active analogues that are capable of inducing pathogenesis-related genes and enhanced resistance. Interestingly, induction of both genes by TMV infection was still observed in resistant tobacco plants expressing the bacterial salicylate hydroxylase gene (nahG), although the levels of induction appeared to be reduced. Identification of pathogen- and SA-induced genes encoding WRKY DNA-binding proteins should facilitate future studies on the regulation and functions of this novel group of DNA-binding proteins.
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  • 29
    ISSN: 1573-5028
    Keywords: gene expression ; glutamine synthetase ; legume-Rhizobium symbiosis ; nitrogen assimilation ; root nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we have studied the localisation of expression of the two functional cytosolic glutamine synthetase (GS) genes, MtGSa and MtGSb, in root nodules of the model legume Medicago truncatula. We have used a combination of different techniques, including immunocytochemistry, in situ hybridisation and promoter β-glucuronidase (GUS) fusions in transgenic plants, to provide the means of correlating gene expression with protein localisation. These studies revealed that transcriptional regulation (mRNA synthesis) plays an important part in controlling GS protein levels in nodules of M. truncatula. The major locations of cytosolic GS mRNA and protein are the central tissue, the parenchyma and the pericycle of the vascular bundles. These findings indicate that in nodules, GS might be involved in other physiological processes in addition to the primary assimilation of ammonia released by the bacterial nitrogenase. The two genes show different but overlapping patterns of expression with MtGSa being the major gene expressed in the infected cells of the nodule. Promoter fragments of 2.6 kb and 3.1 kb of MtGSa and MtGSb, respectively, have been sequenced and primer extension revealed that the MtGSb promoter is expressed in nodules from an additional start site that is not used in roots. Generally these fragments in the homologous transgenic system were sufficient to drive GUS expression in almost all the tissues and cell types where GS proteins and transcripts are located except that the MtGSa promoter fragment did not express GUS highly in the nodule infected cells. These results indicate that the cis-acting regulatory elements responsible for infected-cell expression are missing from the MtGSa promoter fragment.
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  • 30
    ISSN: 1573-5028
    Keywords: epidermis ; gene expression ; glycine-rich protein ; lipid transfer protein ; proline-rich protein ; stomata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Guard cells are specialized and metabolically active cells which arise during the differentiation of the epidermis. Using Nicotiana glauca epidermal peels as a source of purified guard cells, we have constructed a cDNA library from guard cell RNA. In order to isolate genes that are predominantly expressed in guard cells, we performed a differential screen of this library, comparing the hybridization of a radiolabeled cDNA probe synthesized from guard cell RNA to that from a mesophyll cell cDNA probe. Sixteen clones were isolated based on their greater level of hybridization with the guard cell probe. Of these, eight had high homology to lipid transfer protein (LTP), two were similar to glycine-rich protein (GRP), and one displayed high homology to proline-rich proteins from Arabidopsis thaliana (AtPRP2, AtPRP4) and from potato guard cells (GPP). Northern analysis confirmed that one or more NgLTP genes, NgGRP1, and NgGPP1 are all differentially expressed, with highest levels in guard cells, and low or undetectable levels in mesophyll cells and in roots. In addition, all are induced to some degree in drought-stressed guard cells. NgLTP and NgGRP1 expression was localized by in situ hybridization to the guard cells and pavement cells in the epidermis. NgGRP1 expression was also detected in cells of the vasculature. Genomic Southern analysis indicated that LTP is encoded by a family of highly similar genes in N. glauca. This work has identified members of a subset of epidermis- and guard cell-predominant genes, whose protein products are likely to contribute to the unique properties acquired by guard cells and pavement cells during differentiation.
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  • 31
    ISSN: 1573-5028
    Keywords: chitinase function ; flower-predominant ; gene expression ; molecular cloning ; monocotyledon ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A flower-predominant cDNA for a gene, termed OsChia1;175, was isolated from a cDNA library of rice pistils. Northern blot and RT-PCR analyses revealed that the OsChia1;175 gene is highly expressed in floral organs (pistils, stamens and lodicules at the heading stage) but not or at an extremely low level in vegetative organs. OsChia1;175 encodes a protein that consists of 340 amino acid residues, and the putative mature protein shows 52% to 63% amino acid identity to class I chitinases of rice or other plants. The phylogenetic tree shows that the OsChia1;175 protein is a new type of plant class I chitinase in rice. The expression of OsChia1;175 in vegetative organs is not induced by several chemicals, UV, and wounding. The soluble putative mature OsChia1;175 protein expressed in Escherichia coli exhibited chitinase activity in the assay with colloidal chitin as a substrate. Genomic Southern analysis revealed that the OsChia1;175 gene was organized as a low-copy gene family. The rice genomic library was screened and a genome clone corresponding to OsChia1;175 was isolated. The transcription start sites of the OsChia1;175 gene were mapped by primer extension analysis. The 1.2 kb putative promoter region of the OsChia1;175 gene was fused to the GUS (β-glucuronidase) gene, and this chimeric gene was introduced to rice by Agrobacterium-mediated transformation. The flower-predominant gene expression was identified also in the transgenic rice plants. The high promoter activity was detected in the stigmas, styles, stamens and lodicules in transgenic plants. The possible functions of OsChia1;175 are discussed.
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  • 32
    ISSN: 1573-5028
    Keywords: anaerobiosis ; electrophoretic mobility shift assays ; gene expression ; glyceraldehyde-3-phosphate dehydrogenase ; Nicotiana tabacum ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The promoter of the maize glyceraldehyde-3-phosphate dehydrogenase 4 gene (GapC4) confers strong, specific and ubiquitous anaerobic reporter gene expression in tobacco. To identify factors required for heterologous anaerobic gene expression, 19 progressive 5′ and 3′ promoter deletions were linked to a chimeric GapC4 TATA box-β-glucuronidase (GUS) reporter gene construct and transformed into tobacco. In all transgenic lines aerobic expression values were in the range obtained for negative controls while histochemical GUS assays reveal some weak expression in roots only. Anaerobic induction of about 100-fold to more than 1000-fold above unspecific background is mediated by a region of about 190 bp of the GapC4 promoter. Anaerobic reporter gene induction strongly decreases upon deletion of a 20 bp fragment from −286 to −266 relative to the transcription start point. This fragment harbours putative cis-acting sequences. Electrophoretic mobility shift assays with a 50 bp fragment harbouring these cis sequences reveal a high-mobility complex that is formed with nuclear extracts from aerobic and anaerobic leaf tissue while an additional low-mobility complex is anaerobiosis-specific. The formation of the high-mobility complex requires the sequence GTGGGCCCG. The 50 bp fragment alone confers weak and orientation-dependent anaerobic induction to a GapC4 TATA box-β-glucuronidase (GUS) reporter gene.
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  • 33
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    Plant molecular biology 43 (2000), S. 659-675 
    ISSN: 1573-5028
    Keywords: A-type cyclins ; cell cycle ; gene expression ; regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although the basic mechanisms which control the progression through the cell cycle appear to be conserved in all higher eukaryotes, the unique features of the plant developmental programme must be somehow reflected in a plant-specific regulation of the factors which control cell division. In the past few years, considerable progress has been achieved in identifying the major components of the cell cycle machinery in plants, especially the cyclin-dependent kinases (CDKs) and their regulatory subunits, the cyclins. The question of how these components direct expression of specific genes at specific stages of the cell cycle, and how they are themselves regulated, constitutes a challenge for the present and for the years to come. This review summarizes our current knowledge of a particular class of plant cyclins, the A-type cyclins, which can be further subdivided into three structural groups. The putative functions of these A-type cyclins are discussed in relation to the presence of remarkable motifs in their amino acid sequences, and to their specific transcriptional regulation, protein amount and subcellular localization.
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  • 34
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    Plant molecular biology 44 (2000), S. 73-84 
    ISSN: 1573-5028
    Keywords: auxin ; Aux/IAA ; dgt ; gene expression ; Lycopersicon esculentum ; signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The diageotropica (dgt) mutation has been proposed to affect either auxin perception or responsiveness in tomato plants. It has previously been demonstrated that the expression of one member of the Aux/IAA family of auxin-regulated genes is reduced in dgt plants. Here, we report the cloning of ten new members of the tomato Aux/IAA family by PCR amplification based on conserved protein domains. All of the gene family members except one (LeIAA7) are expressed in etiolated tomato seedlings, although they demonstrate tissue specificity (e.g. increased expression in hypocotyls vs. roots) within the seedling. The wild-type auxin-response characteristics of the expression of these tomato LeIAA genes are similar to those previously described for Aux/IAA family members in Arabidopsis. In dgt seedlings, auxin stimulation of gene expression was reduced in only a subset of LeIAA genes (LeIAA5, 8, 10, and 11), with the greatest reduction associated with those genes with the strongest wild-type response to auxin. The remaining LeIAA genes tested exhibited essentially the same induction levels in response to the hormone in both dgt and wild-type hypocotyls. These results confirm that dgt plants can perceive auxin and suggest that a specific step in early auxin signal transduction is disrupted by the dgt mutation.
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  • 35
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; calcium-binding protein ; caleosin ; EF-hand ; gene expression ; lipid bodies ; vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have previously identified a rice gene encoding a 27 kDa protein with a single Ca2+-binding EF-hand and a putative membrane anchor. We report here similar genes termed caleosins, CLO, in other plants and fungi; they comprise a multigene family of at least five members in Arabidopsis (AtClo1–5). Northern hybridization demonstrated that AtClo2–4 mRNAs levels were low in various tissues, while AtClo1 mRNA levels were high in developing embryos and mature seeds. Analysis of transgenic Arabidopsis plants expressing the GUS reporter under control of the AtClo1 promoter showed strong levels of expression in developing embryos and also in root tip cells. Antibodies raised against AtCLO1 were used to detect caleosin in cellular fractions of Arabidopsis and rapeseed. This indicated that caleosins are a novel class of lipid body proteins, which may also be associated with an ER subdomain.
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  • 36
    ISSN: 1573-6881
    Keywords: Mitochondrial biogenesis ; copy number ; gene expression ; mitochondrial transcription factor ; nuclear—mitochondrial communication ; stimulation ; endurance training
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Mitochondrial proliferation was studied in chronically stimulated rabbit skeletal muscle over a period of 50 days. After this time, subunits of COX had increased about fourfold. Corresponding mRNAs, encoded on mitochondrial DNA as well as on nuclear genes, were unchanged when related to total tissue RNA, however, they were elevated two- to fivefold when the massive increase of ribosomes per unit mass of muscle was taken into account. The same was true for the mRNA encoding mitochondrial transcription factor A. Surprisingly, tissue levels of mtTFA protein were reduced about twofold, together with mitochondrial DNA. In conclusion, mito chondria are able to maintain high rates of mitochondrial transcription even in the presence of reduced mtTFA protein and mtDNA levels. Therefore, stimulated mtTFA gene expression accompanies stimulated mitochondrial transcription, as in other models, but it is not sufficient for an increase of mtDNA copy number and other, yet unknown, factors have to be postulated.
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  • 37
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    Biotechnology letters 22 (2000), S. 151-155 
    ISSN: 1573-6776
    Keywords: antibacterial peptide ; cecropin ; gene expression ; mammalian cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We have stably transfected a Chinese hamster lung cell line V79 with a recombinant gene construct where the Drosophila cecropin A2 cDNA is under the control of Rous sarcoma virus, long terminal repeat (RSV LTR). We have not only been able to demonstrate expression at the RNA level by Northern analysis but also have detected an unprocessed peptide using an antiserum raised against Hyalophora cecropin.
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  • 38
    ISSN: 1573-6857
    Keywords: dendritic polymer ; reporter gene ; gene expression ; transfection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyclic core dendritic polymer is a new type of synthetic polymers. The ability of generation 4 of the dendrimer with a core of 1,4,7,10-tetraazacyclododecane to function as an effective gene delivery vector was investigated. Results from fluorescence in situhybridization (FISH) show that the pCH 110 plasmid DNA was transferred into human small intestine cancer metastatic ascites (HICMA) cells induced by this kind of dendrimer as a vector. The transferred LacZ, GFP and luciferase genes were highly expressed in the transfected HICMA, COS-7 and 293 cells. These studies demonstrate that the dendrimer can transfect mammalian cells in vitrowhich offers an alternatively efficient method for mammalian gene transfer.
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  • 39
    ISSN: 1573-2568
    Keywords: keratinocyte growth factor ; KGF receptor ; gene expression ; intestine ; nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to investigate the regulation of keratinocyte growth factor (KGF) and KGF receptor mRNAs by diet and KGF treatment in rat intestine. Fasting for three days up-regulated KGF and KGF receptor mRNA levels in ileum and increased KGF receptor mRNA expression in colon. KGF and KGF receptor mRNA levels returned toward control values with ad libitum refeeding but remained elevated when refeeding was limited to 25% of ad libitum intake. KGF treatment during nutrient repletion did not alter intestinal KGF mRNA levels but increased KGF receptor mRNA abundance in ileum and colon. We conclude that the increase in KGF and KGF receptor mRNAs induced by malnutrition may be an adaptive response to attenuate gut mucosal atrophy in this setting. The gut-trophic effects of KGF treatment may be mediated, in part, by up-regulation of the KGF receptor mRNA in small bowel and colon.
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  • 40
    ISSN: 1572-9699
    Keywords: differentiation ; FtsZ ; gene expression ; septum ; SsgA ; transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper describes the effects of increased expression of the cell division genes ftsZ, ftsQ, and ssgA on the development of both solid- and liquid-grown mycelium of Streptomyces coelicolor and Streptomyces lividans. Over-expression of ftsZ in S. coelicolor M145 inhibited aerial mycelium formation and blocked sporulation. Such deficient sporulation was also observed for the ftsZ mutant. Over-expression of ftsZ also inhibited morphological differentiation in S. lividans 1326, although aerial mycelium formation was less reduced. Furthermore, antibiotic production was increased in both strains, and in particular the otherwise dormant actinorhodin biosynthesis cluster of S. lividans was activated in liquid- and solid-grown cultures. No significant alterations were observed when the gene dosage of ftsQ was increased. Analysis by transmission electron microscopy of an S. coelicolor strain over-expressing ssgA showed that septum formation had strongly increased in comparison to wild-type S. coelicolor, showing that SsgA clearly influences Streptomyces cell division. The morphology of the hyphae was affected such that irregular septa were produced with a significantly wider diameter, thereby forming spore-like compartments. This suggests that ssgA can induce a process similar to submerged sporulation in Streptomyces strains that otherwise fail to do so. A working model is proposed for the regulation of septum formation and of submerged sporulation.
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  • 41
    ISSN: 1572-994X
    Keywords: bacteriophage MB78 ; contiguous ORF ; unusual start codons ; genome analysis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Four proteins of bacteriophage MB78 having apparent molecular weights as 35, 14, 21 and 16 kDa are expressed from 3.9 kb SalI-HindIII fragment located almost in the middle of the phage genome. Analysis of the sequence supported by some experimental evidences suggest that these four proteins are expressed from polycistronic message without any intercistronic gap. Stop and start codons of consecutive ORFs overlap and rare initiation codons are used. Computer analysis of the sequence suggests the presence of two more open reading frames within the ORFs of 35 and 16 kDa proteins but in the opposite orientation, i.e. in the complementary strand.
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  • 42
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    Plant growth regulation 30 (2000), S. 193-200 
    ISSN: 1573-5087
    Keywords: ACC synthase ; ACC oxidase ; ethylene ; fruit ; gene expression ; regulation ; ripening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Progress in ethylene regulating fruit ripening concerning itsperception and signal transduction and expression of ACC synthaseand ACC oxidase genes is reviewed. ACC synthase and ACC oxidasehave been characterized and their genes cloned from various fruittissues. Both ACC synthase and ACC oxidase are encoded bymultigene families, and their activities are associated withfruit ripening. In climacteric fruit, the transition toautocatalytic ethylene production appears to be due to a seriesof events in which ACC sythase and ACC oxidase genes have beenexpressed developmentally. Differential expression of ACCsynthase and ACC oxidase gene family members is probably involvedin such a transition that ultimately controls the onset of fruitripening.In comparison to ACC synthase and ACC oxidase, less is knownabout ethylene perception and signal transduction because of thedifficulties in isolating and purifying ethylene receptors orethylene-binding proteins using biochemical methods. However, theidentification of the Nr tomato ripening mutant as anethylene receptor, the applications of new potent anti-ethylenecompounds and the generation of transgenic fruits with reducedethylene production have provided evidence that ethylenereceptors regulate a defined set of genes which are expressedduring fruit ripening. The properties and functions of ethylenereceptors, such as ETR1, are being elucidated.Application of molecular genetics, in combination withbiochemical approaches, will enable us to better understand theindividual steps leading from ethylene perception and signaltransduction and expression of ACC synthase and ACC oxidase genefamily member to the physiological responses.
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  • 43
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    Genetic resources and crop evolution 47 (2000), S. 135-140 
    ISSN: 1573-5109
    Keywords: Aegilops tauschii ; gene expression ; genetic inheritance ; Puccinia recondita f. sp. tritici ; rust resistance ; synthetic hexaploid wheats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A collection of 164 Aegilops tauschii accessions, obtained from Gatersleben, Germany, was screened for reaction to leaf rust under controlled greenhouse conditions. We have also evaluated a selection of synthetic hexaploid wheats, produced by hybridizing Ae. tauschii with tetraploid durum wheats, as well as the first and second generation of hybrids between some of these resistant synthetic hexaploid wheats and susceptible Triticum aestivum cultivars. Eighteen (11%) accessions of Ae. tauschii were resistant to leaf rust among which 1 was immune, 13 were highly resistant and 4 were moderately resistant. Six of the synthetic hexaploid wheats expressed a high level of leaf rust resistance while four exhibited either a reduced or complete susceptibility compared to their corresponding diploid parent. This suppression of resistance at the hexaploid level suggests the presence of suppressor genes in the A and/or B genomes of the T. turgidum parent. Inheritance of leaf rust resistance from the intercrosses with susceptible bread wheats revealed that resistance was dominant over susceptibility. Leaf rust resistance from the three synthetics (syn 101, syn 701 and syn 901) was effectively transmitted as a single dominant gene and one synthetic (syn 301) possessed two different dominant genes for resistance.
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  • 44
    ISSN: 1573-5044
    Keywords: fall dormancy ; gene expression ; Medicago sativa L. ; protein ; starch ; sugar ; winter hardiness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A major factor limiting persistence of alfalfa (Medicago sativa L.) in the northern US is poor winter hardiness. Our hypothesis is that suspension cell cultures derived from dormant, winter-hardy alfalfa cultivars would cold acclimate and survive sub-zero temperatures better than cell cultures derived from non-dormant, non-hardy cultivars. Our objectives were (1) to determine if genetic differences in winter hardiness between dormant and non-dormant alfalfa were retained by suspension cells derived from these contrasting cultivars; and (2) to determine the physiological and biochemical bases for differences in freezing tolerance of suspension cells. Cell suspensions derived from `5262' (fall dormant) and `5929' (fall non-dormant) were cold hardened at 2 °C for 14 days. Cells were frozen in a cooling bath and cell survival determined by measuring 2, 3, 5-triphenyltetrazolium chloride (TTC) reduction. Cold acclimation improved cell survival of both cultivars to −5 °C when compared to unacclimated cells. Only acclimated cells of 5262 survived temperatures of −10 °C to −25 °C. The freezing tolerance of cold-acclimated 5262 cells was associated with high sugar and starch concentrations, lower α-amylase activities and slightly lower cell protein levels when compared to 5929. No differences in polypeptide composition were evident when comparing acclimated and unacclimated cells of 5929, but polypeptide composition did change with acclimation of 5262 cells. As expected, expression of RootCAR1 in 5262 cells increased with cold acclimation, but high levels of RootCAR1 transcript were unexpectantly found in both cold acclimated and unacclimated 5929 cells. With the exception of the RootCAR1 expression, many of the physiological responses of these alfalfa cell lines to cold acclimation were similar to those that have been reported for field-grown plants.
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  • 45
    ISSN: 1573-5028
    Keywords: C4 photosynthesis ; maize ; phosphoenolpyruvate carboxylase ; transgenic plant ; transcription ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract C4-type phosphenolpyruvate carboxylase (C4PEPC) acts as a primary carbon assimilatory enzyme in the C4 photosynthetic pathway. The maize C4PEPC gene (C4Ppc1) is specifically expressed in mesophyll cells (MC) of light-grown leaves, but the molecular mechanism responsible for its cell type-specific expression has not been characterized. In this study, we introduced a chimeric maize C4Ppc1 5′-flanking region/β-glucuronidase (GUS) gene into maize plants by Agrobacterium-mediated transformation. Activity assay and histochemical staining showed that GUS is almost exclusively localized in leaf MC of transgenic maize plants. This observation suggests that the introduced 5′ region of maize C4Ppc1 contains the necessary cis element(s) for its specific expression in MC. Next, we investigated whether the 5′ region of the maize gene interacts with nuclear proteins in a cell type-specific manner. By gel shift assays with nuclear extracts prepared from MC or bundle sheath cells (BSC), cell type-specific DNA-protein interactions were detected: nuclear factors PEPIb and PEPIc are specific to MC whereas PEPIa and PEPIIa are specific to BSC. Light alters the binding activity of these factors. These interactions were not detected in the assay with nuclear extract prepared from root, or competed out by oligonucleotides corresponding to the binding sites for the maize nuclear protein, PEP-I, which is known to bind specifically to the promoter region of C4Ppc1. The results suggest that novel cell type-specific positive and negative nuclear factors bind to the maize C4Ppc1 5′-flanking region and regulate its differential transcription in MC in a light-dependent manner.
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  • 46
    ISSN: 1573-5028
    Keywords: gene expression ; nicotinic acid ; pyridine alkaloids ; secondary metabolism ; polyploidy ; wound-induced
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Quinolate acid phosphoribosyltransferase (QPRTase), a key enzyme in nicotinamide adenine dinucleotide (NAD) biosynthesis, also plays an important role in ensuring nicotinic acid is available for the synthesis of defensive pyridine alkaloids in Nicotiana species. In this study, cDNAs for QPRTase were characterized from N. rustica and N. tabacum. Deduced proteins from both cDNAs are almost identical and contain a 24 amino acid N-terminal extension, not reported in other QPRTases, that has characteristics of a mitochondrial targeting sequence. In N. tabacum and N. sylvestris, both of which contain nicotine as the major pyridine alkaloid, QPRTase transcript was detected in roots, the site of nicotine synthesis, but not in leaves. QPRTase transcript levels increased markedly in roots of both species 12–24 h after damage to aerial tissues, with a concomitant rise in transcript levels of putrescine N-methyltransferase (PMT), another key enzyme in nicotine biosynthesis. In N. glauca, however, in which anabasine represents the major pyridine alkaloid, QPRTase transcript was detected in both leaf and root tissues. Moreover, wound induction of QPRTase but not PMT was observed in leaf tissues, and not in roots, 12–24 h after wounding. Southern analysis of genomic DNA from the Nicotiana species noted above, and also several others from within the genus, suggested that QPRTase is encoded by a small gene family in all the species investigated.
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  • 47
    ISSN: 1573-5028
    Keywords: gene expression ; heterologous expression ; H+/hexose symporter ; Lycopersicon esculentum ; quantitative PCR ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A full-length (LeHT2) and two partial (LeHT1 and LeHT3) cDNA clones, encoding hexose transporters, were isolated from tomato (Lycopersicon esculentum) fruit and flower cDNA libraries. Southern blot analysis confirmed the presence of a gene family of hexose transporters in tomato consisting of at least three members. The full-length cDNA (LeHT2) encodes a protein of 523 amino acids, with a calculated molecular mass of 57.6 kDa. The predicted protein has 12 putative membrane-spanning domains and belongs to the Major Facilitator Superfamily of membrane carriers. The three clones encode polypeptides that are homologous to other plant monosaccharide transporters and contain conserved amino acid motifs characteristic of this superfamily. Expression of the three genes in different organs of tomato was investigated by quantitative PCR. LeHT1 and LeHT3 are expressed predominantly in sink tissues, with both genes showing highest expression in young fruit and root tips. LeHT2 is expressed at relatively high levels in source leaves and certain sink tissues such as flowers. LeHT2 was functionally expressed in a hexose transport-deficient mutant (RE700A) of Saccharomyces cerevisiae. LeHT2-dependent transport of glucose in RE700A exhibited properties consistent with the operation of an energy-coupled transporter and probably a H+/hexose symporter. The K m of the symporter for glucose is 45 μM.
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  • 48
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; β-glucuronidase (GUS) reporter gene ; farnesyl diphosphate synthase ; gene expression ; isoprenoids ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Farnesyl diphosphate synthase (FPS), the enzyme that catalyses the synthesis of farnesyl diphosphate (FPP) from isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), is considered a regulatory enzyme of plant isoprenoid biosynthesis. The promoter regions of the FPS1 and FPS2 genes controlling the expression of isoforms FPS1S and FPS2, respectively, were fused to the β-glucuronidase (GUS) reporter gene and introduced into Arabidopsis thaliana plants. The FPS1S:GUS gene is widely expressed in all plant tissues throughout development, thus supporting a role for FPS1S in the synthesis of isoprenoids serving basic plant cell functions. In contrast, the FPS2:GUS gene shows a pattern of expression restricted to specific organs at particular stages of development. The highest levels of GUS activity are detected in flowers, especially in pollen grains, from the early stages of flower development. After pollination, much lower levels of GUS activity are detected in the rest of floral organs, with the exception of the ovary valves, which remain unstained throughout flower development. GUS activity is also detected in developing and mature seeds. In roots, GUS expression is primarily detected at sites of lateral root initiation and in junctions between primary and secondary roots. No GUS activity is detected in root apical meristems. GUS expression is also observed in junctions between primary and secondary stems. Overall, the pattern of expression of FPS2:GUS suggests a role for FPS2 in the synthesis of particular isoprenoids with specialized functions. Functional FPS2 gene promoter deletion analysis in transfected protoplasts and transgenic A. thaliana plants indicate that all the cis-acting elements required to establish the full pattern of expression of the FPS2 gene are contained in a short region extending from positions −111 to +65. The potential regulatory role of specific sequences within this region is discussed.
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  • 49
    ISSN: 1573-6776
    Keywords: alcohol oxidase ; gene expression ; human growth hormone ; Pichia pastoris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Mature human growth hormone (hGH) cDNA was cloned by homologous recombination into the yeast Pichia pastoris genome. The hGH gene expression was placed under the control of the methanol-inducible alcohol oxidase 1 (AOX1) gene promoter and the Saccharomyces cerevisiae α-factor signal sequence to direct the secretion of recombinant human growth hormone (rhGH) into the growth medium. O2-limited induction of recombinant yeast strains in shake tubes with 3 ml of culture medium produced up to 11 mg rhGH l−1, while high cell density cultures using a 2-l bioreactor produced about 49 mg rhGH l−1 achieving 40% of total protein of the culture medium supernatant.
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  • 50
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    Biotechnology letters 22 (2000), S. 789-794 
    ISSN: 1573-6776
    Keywords: gene expression ; PCR cloning ; pha genes ; polyhydroxyalkanoates ; Pseudomonas resinovorans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A ca. 5.5-kb region of Pseudomonas resinovorans genome containing the polyhydroxyalkanoate (PHA) biosynthesis locus was sequenced. Three complete open-reading-frames (ORFs), i.e., phaC1 Pr, phaZ Pr, and phaC2 Pr, were identified. Using this sequence information, phaC1 Pr was PCR-cloned from P. resinovorans genomic DNA and expressed in E. coli as shown by a Nile Red plate assay and gas chromatography/mass spectrometric analysis.
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  • 51
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    Aerobiologia 16 (2000), S. 331-334 
    ISSN: 1573-3025
    Keywords: allergenic pollen ; gene expression ; molecular biology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The molecular mechanism of gene expression for pollen specificity is not yet fully known. However, it is an exciting area with great potential and has a wide scope of application in the field of molecular biology, breeding systems, biotechnology etc. The main aim of this write-up is to review some of the interesting achievements made through studies like gene expression in allergic pollen and the research which will make a way towards practical application of pollen molecular biology in identifying and isolating the genes responsible for all allergic disorders reported among various individuals.
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  • 52
    ISSN: 1573-0778
    Keywords: gene expression ; immortalised hepatocytes ; RAP-PCR ; RT-PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Primary rat hepatocytes dedifferentiate rapidly losing theactivities of the drug metabolising enzymes involved in thedetoxification of xenobiotics in the liver. An alternativeapproach to using primary hepatocytes for toxicity testing isthe development of immortalised hepatocyte cell lines via thetransfection of primary hepatocytes with SV40 DNA. In order toassess the suitability of immortalised lines as an alternativeto primary cell cultures we have used RNA arbitrarily primedpolymerase chain reaction to compare gene expression inimmortalised rat hepatocyte cell lines with that in primary rathepatocytes. We have found that differences exist in the RNAtranscripts between fresh and immortalised hepatocyteshighlighting RNA arbitrarily primed polymerase chain reaction asa useful screening method for identifying immortalised lineswhich retain the most `normal' phenotype in relation to theprimary cells from which they originated.
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  • 53
    ISSN: 1573-0778
    Keywords: cDNA ; differentiation ; gene expression ; growth ; humancells ; human tissues ; mitochondrial DNA ; mitochondrial RNA ; polyadenylated RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In the mitochondrion, essential genetic elements for replication and transcription are mostly housed within a shortsegment of its DNA located between tRNAPhe and tRNAPro genes, which is called mitochondrial regulatoryregion (mrr). RNAs are known to be transcribed from mrr, thestructures and the functions of which are yet to be fullycharacterized.We detected ca. 1.3 kb H-strand transcripts of mrr (mrrH-RNAs),and 0.2 kb L-strand transcripts of mrr (mrrL-RNAs) in varioushuman cultured cells and tissues using double stranded mrrDNAprobes. The steady state levels of mrrL-RNAs were generally highin cultured cells, while they varied among tissues. On the otherhand, the levels of mrrH-RNAs varied among tissues and amongcultured cells. A tendency was observed in these cells andtissues that a high level of mrrL-RNA is associated with cellproliferation, and a high level of mrrH-RNA withdifferentiation. Several cDNA clones to 1.3 kb mrrH-RNA were obtained from humanskeletal muscle polyadenylated RNAs. The 5′ terminus of the 1.3 kb RNA was determined to be at nucleotide position 15953 whichis immediately downstream of tRNAThr sequence.Polyadenylation site for most of the clones was demonstrated tobe at nucleotide position 576 which is immediately upstream oftRNAPhe sequence. The longest cDNA insert obtained was 1177 bps long spanning from nucleotide positions 15969 to 576 which could code for a peptide of 76 amino acids. The cDNAs isolatedhere are the first cDNA clones reported to human mrrH-RNAs.These results, together with previous results, furthersubstantiate that polyadenylated mrrH- and mrrL-RNAs are commonly present at varying levels among human tissues andcells. The 3′ end sequences of the cloned mrrH-cDNA provideswith insights into the mechanisms of transcription termination.The cDNA clones will provide tools to further the study of thefunction of mrr RNAs.
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  • 54
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    Bulletin of experimental biology and medicine 130 (2000), S. 898-899 
    ISSN: 1573-8221
    Keywords: peptides ; gene expression ; interleukin-2 ; lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Lys-Glu in vitro stimulated interleukin-2 gene expression in mouse spleen lymphocytes. This effect depended on peptide concentration and duration of treatment. It is hypothesized that this peptide is the shortest regulatory fragment promoting the transport of trans-acting factors into the nucleus. It can not be excluded that Lys-Glu is a structural component of trans-acting factor active centers, which are necessary for the activation of interleukin-2 gene transcription in lymphocytes.
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  • 55
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    Bulletin of experimental biology and medicine 130 (2000), S. 1159-1161 
    ISSN: 1573-8221
    Keywords: erythroblasts ; cytokines ; gene expression ; hemopoietic stem cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Transplantation of erythroid and bone marrow cells to irradiated mice stimulated exogenous colony formation. Pretreatment of erythroid cells with specific rabbit antiserum to erythroblasts abolished this effect. The reverse transcriptase polymerase chain reaction revealed the presence of mRNA for interleukin-1α, interleukin-1β, interleukin-3, interleukin-6, and granulocyte-macrophage colony-stimulating factor in erythroid cells. Granulocyte-macrophage colony-stimulating factor was found in the conditioned medium from erythroid cells. Thus, erythroid cells stimulated colony-forming activity of bone marrow cells, which was probably mediated via cytokine synthesis (e.g., granulocyte-macrophage colony-stimulating factor).
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  • 56
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    Biologia plantarum 43 (2000), S. 481-489 
    ISSN: 1573-8264
    Keywords: cell symmetry ; gene expression ; heat shock proteins ; polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryogenesis can be initiated directly from microspores or pollen grains. This is known as androgenesis and refers to the process of redirection of normal pollen development (gametophytic pathway) towards the embryo formation (sporophytic). This review mainly deals with the current knowledge of stress and developmental aspects of induction of androgenesis. The crucial role of stress inductive treatment together with changes in cell polarity are discussed in relation to other relevant biological systems. The intriguing speculations are made on the basis of these comparisons which may point out the direction of future investigations.
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  • 57
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    Cellular and molecular life sciences 50 (1994), S. 958-962 
    ISSN: 1420-9071
    Keywords: Plasminogen activator ; active oxygen ; gene expression ; radical scavengers ; endothelial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Active oxygen, produced by cultured cells following stimulation with various growth factors, seems to be involved in signal transduction leading to cellular responses such as gene expression and growth modulation. In the present study, the intracellular oxidation state was measured in immortalized human endothelial cells (ECV304) after treatment with tumor necrosis factor (TNF)α, using a fluorescent dye and a laser-scanning confocal microscope. The intracellular oxidation state was increased 60 min after the addition of TNFα, and this increase was abolished by a radical scavenger, N-acetylcysteine (NAC), which is also a precursor of glutathione, and by pyrrolidine dithiocarbamate (PDTC). TNFα increased the steady state level of urokinase-type plasminogen activator (uPA), and NAC inhibited this increase at a dose that also inhibited the increase in the intracellular oxidation state. PDTC, on the other hand, did not affect the induction of the uPA gene by TNFα. These results suggest that intracellular glutathione level rather than the oxidation state is necessary for the induction of the uPA gene by TNFα.
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  • 58
    ISSN: 1432-0428
    Keywords: Type 1 (insulin-dependent) diabetes mellitus ; gene expression ; skeletal muscle ; glycogen synthase ; phosphofructokinase ; hexokinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of the present study was to determine whether short-term appropriate insulinization of Type 1 (insulin-dependent) diabetic patients in longterm poor glycaemic control (HbA1C〉9.5%) was associated with an adaptive regulation of the activity and gene expression of key proteins in muscle glycogen storage and glycolysis: glycogen synthase and phosphofructokinase, respectively. In nine diabetic patients biopsies of quadriceps muscle were taken before and 24-h after intensified insulin therapy and compared to findings in eight control subjects. Subcutaneous injections of rapid acting insulin were given at 3-h intervals to improve glycaemic control in diabetic patients (fasting plasma glucose decreased from 20.8±0.8 to 8.7±0.8 mmol/l whereas fasting serum insulin increased from 59±8 to 173±3 pmol/l). Before intensified insulin therapy, analysis of muscle biopsies from diabetic patients showed a normal total glycogen synthase ctivity but a 48% decrease (p=0.006) in glycogen synthase fractional velocity (0.1 mmol/l glucose 6-phosphate) (FV0.1) and a 45% increase (p=0.01) in the half-maximal activation constant of glycogen synthase (A0.5). The activity of phosphofructokinase and the specific mRNA and immunoreactive protein levels of both glycogen synthase and phosphofructokinase were similar in the two groups. The 2.8-fold increase in serum insulin levels and the halving of the plasma glucose level for at least 15 h were associated with a normalization of glycogen synthase fractional activity (FV0.1) and of the half-maximal activation constant (A0.5) whereas the enzyme activity of phosphofructokinase and the mRNA and protein levels of both glycogen synthase and phosphofructokinase remained normal. In conclusion: 1) Reduced allosterical activation of glycogen synthase in muscle of Type 1 diabetic patients in poor metabolic control occurs in the presence of normal total activity as well as normal immunoreactive protein mass and mRNA level of glycogen synthase. 2) Changes in serum insulin within the physiological range play no role in the short-term regulation of glycogen synthase mRNA and protein abundance in muscle from Type 1 diabetic patients.
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  • 59
    ISSN: 1432-0428
    Keywords: Key words Vanadium ; lipogenic enzymes ; gene expression ; streptozotocin-diabetic rats.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Vanadium is a potent insulinomimetic agent. In vivo, its blood glucose lowering action in insulin-deficient diabetic rats is associated with corrected expression of genes involved in hepatic glucose metabolism. In this study, we investigated whether vanadate treatment also reverses the impaired expression of genes coding for key enzymes of lipogenesis in diabetic liver and white adipose tissue. Oral administration of vanadate to streptozotocin-rats caused a 55 % fall in plasma glucose levels after feeding without modifying low insulinaemia. It also partially corrected the low thyroid hormone concentrations. In untreated diabetic animals, hepatic mRNA levels of acetyl-CoA carboxylase and fatty acid synthase were reduced by more than 80 and 90 %, respectively, in close correlation with changes in enzyme activities. Three weeks of vanadate treatment totally restored acetyl-CoA carboxylase mRNA and partially restored fatty acid synthase mRNA (71 % of control levels). The activities of both lipogenic enzymes were increased 3.5 to 4-fold, to reach 45 to 65 % of control values. By contrast, in white adipose tissue, vanadate modified neither expression nor activity of both lipogenic enzymes, which remained blunted (〈 10 % of control levels). In conclusion, vanadate treatment partially restores the activities of two key lipogenic enzymes in liver, but not in white adipose tissue, of diabetic rats. This correction results from a reversal of impaired pre-translational regulatory mechanisms possibly mediated by an improvement of thyroid function and a selective restoration of liver glycolytic flux. [Diabetologia (1994) 37: 1065–1072]
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  • 60
    ISSN: 1432-0428
    Keywords: Pancreas ; growth factors ; gene expression ; beta cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The Reg/pancreatic stone protein (PSP) gene is postulated to be an important regulator of pancreatic beta-cell growth. To investigate this hypothesis, we analysed the expression of the Reg/PSP gene following a 90% pancreatectomy and after chronic glucose infusion, two well-defined models of pancreatic beta-cell growth. There was a rapid induction of the Reg/PSP gene in the remnant pancreas after a 90% pancreatectomy in rats during the period of marked growth of the exocrine and islet tissue. However, a similar rapid, but smaller, induction of the Reg/PSP gene was observed in sham-operated rats and in non-surgical control rats in which there was no enhanced pancreatic growth. Furthermore, there was no pancreatic Reg/PSP gene induction in a model of selective beta-cell growth, the chronic glucose-infused rat. Thus, it is unlikely that Reg/PSP is a beta-cell specific growth factor, even though the function of this important pancreatic gene is still unknown.
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  • 61
    ISSN: 1432-0428
    Keywords: Key words Pancreas ; growth factors ; gene expression ; beta cells.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The Reg/pancreatic stone protein (PSP) gene is postulated to be an important regulator of pancreatic beta-cell growth. To investigate this hypothesis, we analysed the expression of the Reg/PSP gene following a 90 % pancreatectomy and after chronic glucose infusion, two well-defined models of pancreatic beta-cell growth. There was a rapid induction of the Reg/PSP gene in the remnant pancreas after a 90 % pancreatectomy in rats during the period of marked growth of the exocrine and islet tissue. However, a similar rapid, but smaller, induction of the Reg/PSP gene was observed in sham-operated rats and in non-surgical control rats in which there was no enhanced pancreatic growth. Furthermore, there was no pancreatic Reg/PSP gene induction in a model of selective beta-cell growth, the chronic glucose-infused rat. Thus, it is unlikely that Reg/PSP is a beta-cell specific growth factor, even though the function of this important pancreatic gene is still unknown. [Diabetologia (1994) 37: 994–999]
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  • 62
    ISSN: 1432-0428
    Keywords: Vanadium ; lipogenic enzymes ; gene expression ; streptozotocin-diabetic rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Vanadium is a potent insulinomimetic agent. In vivo, its blood glucose lowering action in insulin-deficient diabetic rats is associated with corrected expression of genes involved in hepatic glucose metabolism. In this study, we investigated whether vanadate treatment also reverses the impaired expression of genes coding for key enzymes of lipogenesis in diabetic liver and white adipose tissue. Oral administration of vanadate to streptozotocin-rats caused a 55% fall in plasma glucose levels after feeding without modifying low insulinaemia. It also partially corrected the low thyroid hormone concentrations. In untreated diabetic animals, hepatic mRNA levels of acetyl-CoA carboxylase and fatty acid synthase were reduced by more than 80 and 90%, respectively, in close correlation with changes in enzyme activities. Three weeks of vanadate treatment totally restored acetyl-CoA carboxylase mRNA and partially restored fatty acid synthase mRNA (71% of control levels). The activities of both lipogenic enzymes were increased 3.5 to 4-fold, to reach 45 to 65% of control values. By contrast, in white adipose tissue, vanadate modified neither expression nor activity of both lipogenic enzymes, which remained blunted (〈10% of control levels). In conclusion, vanadate treatment partially restores the activities of two key lipogenic enzymes in liver, but not in white adipose tissue, of diabetic rats. This correction results from a reversal of impaired pre-translational regulatory mechanisms possibly mediated by an improvement of thyroid function and a selective restoration of liver glycolytic flux.
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  • 63
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; rat liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The involvement of a hypocalcemic hormone calcitonin (CT) in the expression of hepatic Ca2+-binding protein regucalcin mRNA was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb). A single oral administration of calcium chloride (100 mg Ca/100 g body weight) to rats induced a remarkable increase in the serum calcium concentration and a corresponding elevation of the liver calcium content during 120 min after the administration. Thyroparathyroidectomy (TPTX) did not cause a significant increase in the liver calcium content after calcium administration. Hepatic regucalcin mRNA level was markedly elevated by calcium administration; the level was about 180% of controls at 60 min after the administration. This increase was completely abolished by TPTX. A single subcutaneous administration of CT (synthetic eel CT; 25–100 MRC mU/100 g) to TPTX rats received oral administration of calcium (100 mg/100 g) produced a remarkable increase in hepatic regucalcin mRNA levels; the level was about 280% of controls with the dose of 25 MRC mU CT/100 g. The present finding suggests that the expression of hepatic mRNA is stimulated by CT, and that the hormonal effect is mediated through Ca2+ in rat liver.
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  • 64
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; phenobarbital ; rat liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The effect of phenobarbital on the expression of calcium-binding protein regucalcin mRNA in rat liver was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin cDNA (0.9 kb of open reading frame). Phenobarbital (4, 8 and 12 mg/ 100 g body weight) was intraperitoneally administered to rats 3 times with 24 h intervals, and the animals were sacrificed by bleeding at 24 h after the last administration. The hepatic regucalcin mRNA levels were markedly reduced by phenobarbital administration. This decrease was about 50% of control level with the 12 mg/100 g dose. Moreover, the hepatic regucalcin concentration was significantly decreased by the administration of phenobarbital (12 mg/100 g), although the serum regucalcin concentration was not altered appreciably. Meanwhile, serum transaminases (GOT and GPT) activities were not increased by the administration of phenobarbital (4 and 12 mg/100 g). The present study demonstrates that the expression of hepatic regucalcin mRNA is decreased by phenobarbital administration in rats, suggesting that regucalcin does not have a role in drug metabolism related to phenobarbital.
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  • 65
    ISSN: 1573-4919
    Keywords: pressure overload ; myocardium ; gene expression ; fibroblast ; extracellular matrix ; ventricular hypertrophy ; growth factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Transforming Growth Factor-beta1 (TGF-β1) is expressed in the heart by muscle and non-muscle cardiac cells.In vitro, cardiac myocytes and non-muscle cells including cardiac fibroblasts and endothelial cells respond to regulatory effects of TGF-β1. Expression of TGF-β1 in the heart is subject to regulation by hemodynamic stimuli. Increased expression of mRNA transcripts for TGF-β1 has been reported in several models of cardiac hypertrophy. The objective of this study was to determine the effect of TGF-β1 in the myocardium. TGF-β1 was injected intravenously. Expression of mRNA transcripts for functional and structural proteins was determined by Northern hybridization analysis. DNA synthesis was determined by measurement of3H-thymidine incorporation into ventricular DNA. The results showed differential regulation of mRNAs for myocyte- and non-myocyte-specific proteins in the heart of TGF-β1 treated rats. Moderate but statistically significant decrease in DNA synthesis was observed in the heart of TGF-β1 treated rats (37.5%, P〈0.025). Together, these data point to a physiological role for TGF-β1 in the heart. They further suggest that similar to its diversein vitro cell-specific regulatory effects, TGF-β1 may have multicellular targets in the heart. Effect of TGF-β1 alone or combined with those of other cytokines/hormones that come into play, as the result of its administration, may be responsible for altered gene expression and DNA synthesis in the myocardium. We propose that in experimental models of myocardial hypertrophy which are associated with increased expression of TGF-β1 in the heart, the contribution of regulatory effects of this growth factor to the manifestations of ventricular hypertrophy could be significant.
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  • 66
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    Molecular and cellular biochemistry 135 (1994), S. 79-88 
    ISSN: 1573-4919
    Keywords: calcium ; nucleus ; calpain ; calmodulin ; cell division ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Calcium has long been known to play a role as a key cytoplasmic second messenger, but until relatively recently its possible involvement in nuclear signal transduction and the regulation of nuclear events has not been extensively studied. Evidence revealing the presence of transmembrane nuclear Ca2+ gradients and a variety of intranuclear Ca2+ binding proteins has fueled renewed interest in this key ion and its involvement in cell-cycle timing and division, gene expression, and protein activation. This review will offer an overview of the current state of knowledge and theory regarding calcium orchestration of nuclear functions and events and discuss possible future directions in this field of study.
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  • 67
    ISSN: 1573-4919
    Keywords: poly(ADP-ribosyl) transferase (human) ; autoregulation ; gene expression ; promoter structure ; cruciform structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Human nuclear poly(ADP-ribosyl)transferase (ADPRT) modifies proteins with branched ADP-ribose-polymers. Various proteins, including ADPRT itself, serve as acceptors for polyADP-ribose. Target proteins include those controlling basic cellular processes such as DNA repair, differentiation and proliferation. Because of the outstanding features of this enzyme: automodification, several functional domains and central role in physiology of the cell, the molecular biology of ADPRT gained wide interest. The promoter structure contains several CCAAT/TATA boxes and SP1 sites. However, there is no CCAAT/TATA box in the neighbourhood of an SP1 site and, thus no obvious site for initiation of transcription. Within this region there are several noteworthy inverted repeats, which by internal basepairing could form two types of cruciform structures. Deletion analysis revealed that these cruciform structures have functional significance. Removal of one type increases the promoter activity, whereas removal of the other diminishes the promoter function. Overexpression of ADPRT from heterologous promoters (MMTV, SV40) leads to repression of the activity of the ADPRT promoter. Indeed, ADPRT was shown to bind specifically to one type of cruciform structure. This specific interaction indicates autorepression of the ADPRT gene: the enzyme ADPRT acts directly as a negative modulator of the activity of its own promoter.
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  • 68
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    Molecular and cellular biochemistry 133-134 (1994), S. 235-243 
    ISSN: 1573-4919
    Keywords: creatine kinase ; mitochondria ; metabolism ; creatine phosphate shuttle ; gene expression ; muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Mitochondrial Creatine Kinase (MtCK) is responsible for the transfer of high energy phosphate from mitochondria to the cytosolic carrier, creatine, and exists in mammals as two isoenzymes encoded by separate genes. In rats and humans, sarcomere-specific MtCK (sMtCK) is expressed only in skeletal and heart muscle, and has 87% nucleotide identity across the 1257 bp coding region. The ubiquitous isoenzyme of MtCK (uMtCK) is expressed in many tissues with highest levels in brain, gut, and kidney, and has 92% nucleotide identity between the 1254 bp coding regions of rat and human. Both genes are highly regulated developmentally in a tissue-specific manner. There is virtually no expression of sMtCK mRNA prior to birth. Unlike cytosolic muscle CK (MCK) and brain CK (BCK), there is no developmental isoenzyme switch between the MtCKs. Cell culture models representing the tissue-specific expression of either sMtCK or uMtCK are available, but there are no adequate developmental models to examine their regulation. Several animal models are available to examine the coordinate regulation of the CK gene family and include 1) Cardiac Stress by coarctation (sMtCK, BCK, and MCK), 2) Uterus and placenta during pregnancy (uMtCK and BCK), and 3) Diabetes and mitochondrial myopathy (sMtCK, BCK, and MCK). We report the details of these findings, and discuss the coordinate regulation of the genes necessary for high-energy transduction.
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  • 69
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    Molecular and cellular biochemistry 135 (1994), S. 89-98 
    ISSN: 1573-4919
    Keywords: calcium ; cell death ; nuclei ; apoptosis ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The last decade has seen the rapid development of research investigating the molecular mechanisms whereby hormones, peptide growth factors and cytokines regulate cell metabolism, differentiation and proliferation. One general signalling mechanism used to transfer the information delivered by agonists into appropriate intracellular compartments involves the rapid Ca2+ redistribution throughout the cell, which results in transient elevations of the cytosolic free Ca2+ concentration. Ca2+ signals are required for a number of cellular processes including the activation of nuclear processes such as gene transcription and cell cycle events. The latter require that appropriate Ca2+ signals elicited in response to agonists be transduced across the nuclear envelope. It has generally been assumed that small molecules, metabolites and ions could freely diffuse across the nuclear envelope. Nevertheless several findings during the past few years have suggested that nuclear pore permeability can be regulated and that ion transport systems and ion-selective channels may exist on the nuclear membranes and regulate intranuclear processes. Intranuclear Ca2+ fluctuations can affect chromatin organization, induce gene expression and also activate cleavage of nuclear DNA by nucleases during programmed cell death or apoptosis. The possible mechanisms involved in nuclear Ca2+ transport and the control of nuclear Ca2+-dependent enzymes in apoptosis is discussed below.
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  • 70
    ISSN: 1573-4978
    Keywords: retinoic acid ; skin ; differential hybridization ; cloning ; keratinocytes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A retinoic acid (RA) inducible skin-specific gene transcript (RIS-1) was isolated by differential hybridization screening of a RA-treated human skin cDNA library. The library was constructed from pooled RNA derived from normal adult human skin treated with alltrans-RA for 4 h (n=6) and 12 h (n=6)in vivo. RIS-1 cDNA corresponded to a 0.6 kb transcript that was barely detectable in normal adult human skin but was significantly induced by 8 h in RA-treated compared to vehicle-treated skin (range 1.1–3.6 fold). Prolonged RA treatment for up to 24 h further increased relative RIS-1 mRNA levels by 1.3–5.5 fold. HPLC analysis of the RA content of 0.1% RA-treated skinin vivo revealed significant levels at 6 h (18.8–120.6 ng RA/g wet weight tissue; approximately 240 nM), immediately preceding the time point at which the increased RIS-1 mRNA level was first seen. This concentration of RA also induced the mRNA levels for cellular RA binding protein II (1.6–19 fold), a marker of RA activity in human skin. RIS-1 mRNA was detected by Northern and dot blotting only in normal skin but not in any other normal human tissues examined, indicating a tissue-specific pattern of gene expression. RIS-1 transcripts were detected at very low levels in untreated cultured human epidermal keratinocytes, while no expression was seen in dermal fibroblasts and melanocytes, the other major cell types in skin. Southern analysis of human and mouse DNA indicated the existence of evolutionarily conserved sequences for RIS-1 between these two species. The polypeptide sequence derived from the partial RIS-1 cDNA was found to be identical to the calcium binding domain found in ‘psoriasin’, a gene whose expression appears to be increased in the skin of psoriasis patients.
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  • 71
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    Plant molecular biology 24 (1994), S. 185-194 
    ISSN: 1573-5028
    Keywords: gene expression ; light/nitrate regulation ; nitrate reductase ; nitrate transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mRNA accumulation pattern of the Chlamydomonas reinhardtii nitrate assimilation-related gene cluster has been elucidated. In ammonium-grown wild-type cells, nit-1 (nitrate reductase, NR), nar-1, nar-2 and nar-3 (nitrate transporter) genes showed very similar kinetics of expression when transferred to nitrate medium. Transcripts of all these genes accumulated transiently in ammonium-grown wild-type cells after a one-hour incubation in nitrogen-free medium, and practically disappeared at about 2 hours. Mutant strains lacking functional nitrate reductase showed similar accumulation kinetics of these transcripts during both nitrate induction and derepression in nitrogen-free media. In contrast to the other nar transcripts, that nar-4, a gene sharing similar sequences with nar-3, accumulated in small amounts in wild-type cells, and only increased after a long nitrate induction period. Nitrate and light showed a strong positive effect on the accumulation of nit-1 gene transcripts. Acetate as a carbon source allowed accumulation of nit-1 mRNA in the dark, indicating the existence of interactions between light and carbon metabolism in nit-1 gene expression. Our data strongly suggest that NR negatively autoregulates its own expression and that of nar genes.
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  • 72
    ISSN: 1573-5028
    Keywords: plant transformation ; chaperonin 60β ; β-glucuronidase ; wound repression ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To study the pattern of gene regulation of the plastid chaperonin 60β gene family a chimaeric gene was constructed fusing the 5′-flanking region of the chaperonin 60β B3 gene to the β-glucuronidase reporter gene. Histochemical and fluorometric analysis of the GUS activity present in transgenic plants harbouring this gene construct showed that the B3 promoter is expressed in leaves, stem, petioles and several flower tissues. The pattern of cell type-specific expression in stems and flowers was found to be developmentally regulated. Expression of the B3 promoter was found not to be heat-inducible, but highly repressed by wounding. The rapid decay in GUS activity upon wounding indicates that, at least under some physiological conditions, the gene product of this reporter gene is not as stable as has been previously thought.
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  • 73
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    Plant molecular biology 24 (1994), S. 879-888 
    ISSN: 1573-5028
    Keywords: barley ; cold acclimation ; gene expression ; low temperature genes ; nuclear run-on transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several low-temperature-responsive (LTR) genes from barley have been shown to have high steady-state transcript levels. Run-on transcription was used to determine the control of expression of these LTR genes. Six of these are shown to be transcriptionally regulated (blt 4/9, blt 101, blt 1015, blt 63, blt 49, blt 410) whilst three are post-transcriptionally regulated (blt 14, blt 411, blt 801). Two transcriptionally regulated genes (blt 4/9 and blt 101) and one post-transcriptionally regulated gene (blt 14) have been used in expression studies. The time course for the appearance and decay of these transcripts is given. Initial appearance and steady-state levels of individual transcripts have different temperature characteristics but no single gene correlates with the cold acclimation response. We suggest that these different response profiles may represent a means of fine-tuning the low-temperature response. One gene, blt 4/9, also accumulated high steady-state levels of transcript in response to drought and a nutrient stress. However, only drought has an acclimating effect on barley plants.
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  • 74
    ISSN: 1573-5028
    Keywords: Spinacia oleracea ; chemical cleavage ; gene expression ; polymerase chain reaction ; protein transport ; SDS-PAGE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The 24 kDa outer envelope membrane protein of spinach chloroplasts (omp24) represents a major constituent of this membrane. Sequences of tryptic and endoprotease Glu-C peptides derived from omp24 allowed the design of oligonucleotides which were used to generate a DNA fragment by polymerase chain reaction using spinach cDNA as template. This fragment served as a probe to screen a cDNA library for a full-length clone of the omp24 coding sequence. The protein predicted from the complete sequence only has 148 amino acids and a molecular mass of 16294 Da. It is an acidic protein (calculated isoelectric point 4.8) with a high content of proline residues. Expression of the coding sequence in Escherichia coli and characterization of the purified recombinant protein produced revealed that the overestimation of its molecular mass by SDS-PAGE (ca. 25 kDa) is due to its abnormal amino acid composition. Despite its rather low hydrophobicity (polarity index 49%), omp24 appears to be deeply embedded in the outer membrane. Insertion of omp24 into the membrane proceeds almost independently of surface receptors or targeting sequence but, in contrast to other known outer envelope membrane proteins, is stimulated by ATP.
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  • 75
    ISSN: 1573-5028
    Keywords: gene expression ; light ; nitrate ; nitrite reductase ; Pimus sylvestris L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A partial cDNA clone (PSnir) encoding the C-terminal region of nitrite reductase was isolated from a λgt 11 library of the gymnospermPimus sylvestris (L.). Nucleotide sequence analysis showed that PSnir contains a reading frame encoding 105 amino acid residues. The amino acid sequence revealed a homology to NiR of 63–68% to dicotyledoneous and of 57–59% to monocotyledoneous species. The protein region implicated to be involved in binding of the prosthetic group is highly conserved between the NiR of the gymnosperm and of angiosperms. In all organs (cotyledonary whorls, hypocotyls, roots) the pattern of NiR gene expression in response to nitrate and light is the same at the level of transcript accumulation and at the enzyme level. This suggests that regulation of NiR gene expression in the Scots pine seedling is predominantly at the level of transcript accumulation. The highest NiR appearance was observed in roots and hypocotyls. In the cotyledonary whorls only small amounts of NiR were found. In roots and hypocotyls the accumulation of NiR mRNA and the appearance of NiR protein is mainly controlled by nitrate, whereas the regulation of NiR gene expression in the whorls is strongly affected by light and the inducive effect of nitrate is only weak.
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  • 76
    ISSN: 1573-5028
    Keywords: castor bean (Ricinus communis) ; catalase gene ; gene expression ; germination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two catalase genes,cat1 andcat2, have been isolated from the castor bean genome. They were located in the same direction on a chromosome at a distance of 2.4 kb,cat1 being on the downstream side ofcat2. The two genes contained introns at the same positions except that one of the 7 introns incat1 is missing incat2 and the corresponding introns differed in size and sequence between the two genes. The translated regions of the two genes had the same number of nucleotides and exhibited 81.3% nucleotide sequence identity. In addition to introns, the nucleotide sequences of the 5′-and 3′-flanking regions are highly divergent between the two genes. In etiolated seedlings,cat1 mRNA was present abundantly in endosperms and cotyledons and only in a small amount in roots. Thecat1 mRNA could not be detected in hypocotyls. By contrast,cat2 mRNA is most abundant in hypocotyls and roots, while endosperms and cotyledons contained only low levels ofcat2 mRNA. Although neithercat1 norcat2 mRNA could be detected in dry seeds, both mRNAs showed temporal accumulation in the endosperm in response to germination. These results suggest that expression of two tightly linked catalase genes of castor bean,cat1 andcat2, are differentially regulated during development.
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  • 77
    ISSN: 1573-5028
    Keywords: β-tubulin ; microtubules ; maize ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four different β-tubulin coding sequences were isolated from a cDNA library prepared from RNA from maize seedling shoots. The four genes (designated tub4, tub6, tub7 and tub8) represented by these cDNA clones together with the tub1 and tub2 genes reported previously encode six β-tubulin isotypes with 90–97.5% amino acid sequence identity. Results from phylogenetic analysis of 17 β-tubulin genes from monocot and dicot plant species indicated that multiple extant lines of β-tubulin genes diverged from a single precursor after the appearance of the two major subfamilies of α-tubulin genes described previously. Hybridization probes from the 3′ non-coding regions of six β-tubulin clones were used to quantify the levels of corresponding tubulin transcripts in different maize tissues including developing anthers and pollen. The results from these dot blot hybridization experiments showed that all of the β-tubulin genes were expressed in most tissues examined, although each gene showed a unique pattern of differential transcript accumulation. The tub1 gene showed a high level of transcript accumulation in meristematic tissues and almost no accumulation in the late stages of anther development and in pollen. In contrast, the level of tub4 transcripts was very low during early stages of male flower development but increased markedly (more than 100 times) during the development of anthers and in pollen. Results from RNAse protection assays showed that this increased hybridization signal resulted from expression of transcripts from one or two genes closely related to tub4. The tub4-related transcripts were not present in shoot tissue. Transcripts from the tub2 gene accumulated to very low levels in all tissues examined, but reached the highest levels in young anthers containing microspore mother cells. RNAse protection assays were used to measure the absolute levels of α- and β-tubulin transcripts in seedling shoot and in pollen. The α-tubulin gene subfamily I genes (tua1, tua2, tua4) contributed the great majority of α-tubulin transcripts in both shoot and pollen. Transcripts from the β-tubulin genes tub4, tub6, tub7, and tub8 were predominant in shoot, but were much less significant than the tub4-related transcripts in pollen.
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  • 78
    ISSN: 1573-5028
    Keywords: gene expression ; b-ZIP motif ; seed storage proteins ; trans-acting factors ; transcription factors ; transcriptional regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Opaque-2 (O2) gene from maize encodes a transcriptional activator of the b-ZIP class. We have isolated and characterized a gene from sorghum, related in sequence to the O2 gene from maize. A single copy of the gene is present in sorghum. Both genomic and cDNA sequences of the O2-related sorghum gene were determined. The sequence is highly homologous to maize O2 both in the promoter and in the coding region. The most closely related sequences contain the b-ZIP domain with only 11 amino acid substitutions in a total of 122 residues. In transient expression assays, the sorghum O2-related coding sequence, expressed from a CaMV 35S promoter, activates expression from the maize b-32 promoter as effectively as that obtained with the maize O2 sequence.
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  • 79
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; dwarf mutant ; gene expression ; gibberellin ; subtractive hybridization ; tonoplast intrinsic protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Arabidopsis ga1 mutant has very low levels of endogenous, active gibberellins and thus has an extreme dwarf phenotype; application of GA3 induces stem elongation and flower development. To test the hypothesis that GA action in this system involves changes in gene expression, we have cloned mRNAs whose abundance changes following GA application. A subtraction cloning scheme for the isolation of differentially regulated cDNAs was established, involving hybridization of single-stranded cDNA to biotinylated mRNA. cDNA populations enriched up to 150-fold in GA-regulated sequences were produced and cDNA libraries generated. Screening of these libraries has isolated two clones that identify mRNAs of ca. 1100 and 750 bases whose abundance is markedly increased 24 h after GA application. One of these clones encodes the vegetative form of the Arabidopsis tonoplast intrinsic protein (γ-TIP), a water channel protein, the expression of which has recently been shown to be correlated with regions of cell expansion. The second clone is expressed only in the inflorescence and encodes a proline- and glycine-rich protein that may be a cell wall component.
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  • 80
    ISSN: 1573-5028
    Keywords: Cucumis melo ; melon ; phenylalanine ammonia-lyase ; gene expression ; ripening ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phenylalanine ammonia-lyase (PAL) is the first enzyme of phenylpropanoid biosynthesis involved in the synthesis of a multiplicity of plant natural products. We have isolated and characterized a nearly fulllength cDNA clone (pmPAL-1) corresponding to a melon fruit (Cucumis melo L. var. reticulatus) gene coding for a protein which is highly similar to PAL from other lants. Melon fruit PAL is transcriptionally induced both in response to fruit ripening and wounding. PAL gene expression follows the kinetics of expression of the ethylene biosynthetic genes during fruit development. In contrast, ethylene biosynthetic genes show different induction kinetics compared to PAL expression in response to wounding. Similar results have been found for two other genes coding for enzymes involved in flavonoid biosynthesis (chalcone synthase, CHS; chalcone isomerase, CHI). Our results imply that regulation of defense gene expression in melon is a co-ordinated process in response to both ethylene and an ethylene-independent wound signal.
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  • 81
    ISSN: 1573-5028
    Keywords: Arabidopsis ; embryo ; gene expression ; oleosin ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Progressive deletions of the 5′-flanking sequences of an Arabidopsis oleosin gene were fused to β-glucuronidase (GUS) and introduced into Brassica napus plants using Agrobacterium-mediated transformation. The effect of these deletions on the quantitative level of gene expression, organ specificity and developmental regulation was assessed. In addition, the influence of abscisic acid (ABA), jasmonic acid (JA), sorbitol and a combined ABA/sorbitol treatment on gene expression was investigated. Sequences that positively regulate quantitative levels of gene expression are present between −1100 to −600 and −400 to −200 of the promoter. In addition, sequences present between −600 and −400 down-regulate quantitative levels of expression. In transgenic B. napus plants, the oleosin promoter directs seed-specific expression of GUS which is present at early stages of seed development and increases throughout seed maturation. Sequences present between −2500 and −1100 of the promoter are involved in modulating the levels of expression at early stages of embryo development. Histochemical staining of embryos demonstrated that expression is uniform throughout the tissues of the embryo. Sequences involved in the response to ABA and sorbitol are present between −400 and −200. The induction of GUS activity by a combined ABA/sorbitol treatment is additive suggesting that ABA is not the sole mediator of osmotically induced oleosin gene expression. A response to JA was only observed when the oleosin promoter was truncated to −600 suggesting that the reported effect of JA on oleosin gene expression may be at a post-transcriptional level.
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  • 82
    ISSN: 1573-5028
    Keywords: abscisic acid ; Arabidopsis thaliana ; gene expression ; mutants ; signal transduction ; stress ; thiol protease ; wilting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sequence and expression characteristics are described of a wilt-inducible gene in Arabidopsis thaliana. A 1494 encodes a potential thiol protease whose mRNA accumulates rapidly in shoot tissue upon the loss of turgor. A1494 mRNA levels peaked after ca. 4 h and declined thereafter. Dehydration also induced rapid biosynthesis of the phytohormone abscisic acid (ABA), which continued for at least 9 h. Exogenous ABA induced the accumulation of A1494 mRNA, with kinetics similar to those after wilting. Rehydration of wilted shoots led to a rapid decline in the content of both ABA and A1494 mRNA. Wilting and ABA independently induced A1494 expression as evidenced by the effects of ABA and wilting on the ABA-deficient aba-1 and ABA-insensitive abi-1 and abi-3 genotypes. A1494 mRNA was not detectable in aba-1 shoots but accumulated rapidly after either wilting or ABA treatment, whereas the shoot ABA content was increased only by ABA treatment. ABA had no effect on A1494 mRNA levels in the abi-1 and abi-3 mutants but wilting did result in enhanced A1494 expression. Heat shock had only a minor effect on A1494 mRNA levels, whereas exposure to low temperature resulted in substantial accumulation of A1494 mRNA in wild-type shoots. However, this latter response, unlike that to drought, was mediated exclusively via ABA synthesis as demonstrated by the lack of A1494 mRNA accumulation in cold-treated aba-1 shoots.
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  • 83
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    Plant molecular biology 25 (1994), S. 369-376 
    ISSN: 1573-5028
    Keywords: ATP synthase ; chloroplast ; gene expression ; plastid ; RNA stability ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plastids present in different tissues may vary morphologically and functionally, despite the fact that all plastids within the same plant contain identical genomes. This is achieved by regulation of expression of the plastid genome by tissue-specific factors, the mechanisms of which are not fully understood. The proton translocating ATP synthase/ATPase is a multisubunit complex composed of nine subunits, six encoded in the plastid and three in the nucleus. We have investigated the tissue-specific expression of the large ATP synthase gene cluster in spinach (Spinacia oleracea). This gene cluster encodes four of the six plastid-encoded ATP synthase genes. Transcript abundance, transcriptional activity, and transcript stability were investigated relative to gene dosage in root plastids and in stem, leaf, and flower chloroplasts. All three of these factors display significant tissue-specific variation. It was intriguing to discover that, although transcript abundance normalized to gene dosage varies in each tissue, transcript abundance as a proportion of the entire plastid RNA population in each tissue is not significantly different. Thus it appears that in these tissues the variation in transcription and stability of transcripts derived from the large ATP synthase gene cluster balances to yield an equivalent proportion of these transcripts in the plastid RNA population. Expression of this gene cluster in photosynthetic as well as non-photosynthetic tissues may facilitate the plasticity of structure and function which is characteristic of plastids.
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  • 84
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    Plant molecular biology 26 (1994), S. 85-93 
    ISSN: 1573-5028
    Keywords: gene expression ; monocot cells ; promoter strength ; transient expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An upstream region isolated from a eukaryotic algal virus adenine methyltransferase gene was tested for promoter function in plants. Fusion of this region to the chloramphenicol acetyltransferase reporter gene resulted in significantly higher expression than fusion with the cauliflower mosaic virus 35S promoter. Strong levels of expression were also found in electroporated monocot plant cells. The promoter activity in transgenic tobacco plants showed tissue-specific expression. Leaves had the highest expression followed by stems and flowers. The promoter activity was not detected in root tissue. Environmental cues, such as light, and the phytohormones auxin and cytokinines had no effect on the promoter's expression. This promoter might be utilized to achieve high levels of expression of introduced genes in higher plants.
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  • 85
    ISSN: 1573-5028
    Keywords: cell cycle ; gene expression ; meristem ; promoter analysis ; transgenic Arabidopsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A genomic clone for the cyc07 gene, which is expressed specifically at the S phase during the cell cycle in synchronous cultures of periwinkle (Catharanthus roseus) cells, was isolated. Determination of the nucleotide sequence of the clone revealed that the cyc07 gene consists of seven exons separated by six introns. Genomic Southern analysis indicated that the cyc07 gene is present as a single copy per haploid genome in periwinkle. Expression of related genes was detected in a wide range of other plants. Transgenic Arabidopsis plants were generated that expressed the gene for β-glucuronidase (GUS) under the control of the promoter of the cyc07 gene. The tissue-specific pattern of expression directed by the promoter was investigated by analysis of GUS activity. Histochemical tests demonstrated that 589 bp of the 5′-upstream sequence of the cyc07 gene could direct specifical expression of the GUS reporter gene in meristematic tissues in transgenic plants. The spatial pattern of expression directed by the promoter was closely correlated with meristematic activity and cell proliferation, suggesting an association between the function of the cyc07 gene and cell proliferation.
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  • 86
    ISSN: 1573-5028
    Keywords: gene expression ; photosynthesis ; protein turnover ; psbA ; tac promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The unicellular cyanobacterium Synechococcus sp. PCC 7942 has three psbA genes encoding two different forms of the photosystem II reaction centre protein D1 (D1:1 and D1:2). The level of expression of these psbA genes and the synthesis of D1:1 and D1:2 are strongly regulated under varying light conditions. In order to better understand the regulatory mechanisms underlying these processes, we have constructed a strain of Synechococcus sp. PCC 7942 capable of over-producing psbA mRNA and D1 protein. In this study, we describe the over-expression of D1:1 using a tac-hybrid promoter in front of the psbAI gene in combination with lacI Q repressor system. Over-production of D1:1 was induced by growing cells for 12 h at 50 μmol photons m-2 s-1 in the presence of 40 or 80 μg/ml IPTG. The amount of psbAI mRNA and that of D1:1 protein in cells grown with IPTG was three times and two times higher, respectively. A higher concentration of IPTG (i.e., 150 μg/ml) did not further increase the production of the psbAI message or D1:1. The over-production of D1:1 caused a decrease in the level of D1:2 synthesised, resulting in most PSII reaction centres containing D1:1. However, the over-production of D1:1 had no effect on the pigment composition (chlorophyll a or phycocyanin/number of cells) or the light-saturated rate of photosynthesis. This and the fact that the total amounts of D1 and D2 proteins were not affected by IPTG suggest that the number of PSII centres within the membranes remained unchanged. From these results, we conclude that expression of psbAI can be regulated by using the tac promoter and lacI Q system. However, the accumulation of D1:1 protein into the membrane is regulated by the number of PSII centres.
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  • 87
    ISSN: 1573-5028
    Keywords: gene expression ; RNA stability regulation ; chloroplast RNA-binding protein (cRBP) ; environmental stress ; Mesembryanthemum crystallinum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report the characterization of transcripts from the halophyte, Mesembryanthemum crystallinum, encoding a protein with high homology to chloroplast RNA-binding proteins (cRBP). In this plant chloroplast-related functions are largely protected against salt stress. cRBP transcripts are derived from a single gene, Mc32crbp, although three size classes of polyadenylated mRNAs are detected. Transcription rate and steady state amounts of mRNA are developmentally regulated and light controlled with strong transcriptional activity as functional chloroplasts are established, and with lower maintenance activity thereafter. Upon salt stress, the rate of transcription decreases, although transcript levels increase. Accompanying stress, a change in the distribution of transcript size classes is observed as the longest transcript with an untranslated 3′ end of 381 nucleotides increases relative to transcripts with shorter 3′ ends. The long transcript is characterized by the presence of five sequence elements in the 3′-untranslated region that are present in cRBP mRNAs from a variety of plants, although not all elements are found in each mRNA. The results may indicate a mechanism by which mRNA levels of constitutively light-regulated genes may be modulated without enhanced transcription in response to environmental cues.
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  • 88
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    Plant molecular biology 26 (1994), S. 1023-1030 
    ISSN: 1573-5028
    Keywords: immunoglobulin genes ; gene expression ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 89
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    Plant molecular biology 26 (1994), S. 1065-1071 
    ISSN: 1573-5028
    Keywords: Brassica ; polyploid ; gene expression ; RT-PCR ; RFLP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One of the essential issues regarding evolution of polyploid species is how duplicate genes are expressed. Most studies on gene expression in polyploids have been based on isozyme analyses; RNA analysis has not been widely used partially due to difficulties in distinguishing homologous transcripts which usually have the same length and similar or almost identical sequences. In this study, a method combining RT-PCR with RFLP was used to analyze transcripts of homologous genes in natural and synthetic Brassica amphidiploids. Sequences coding for several known genes were selected and used to synthesize gene-specific primers. Total RNAs were used as templates for RT-PCR to amplify homologous transcripts in three diploid parental species, three cultivated amphidiploid species and six synthetic amphidiploids. For each gene, initial PCR products amplified in all species had identical length; however, homologous transcripts in the diploid and amphidiploid species could be distinguished after digesting the PCR products with restriction enzymes. Preliminary results based on three genes indicated that both transcripts from the diploid parents were expressed in the synthetic and natural amphidiploids. This study represents the first application of RT-PCR and RFLP analysis to investigate expression of homologous genes in higher plants. The technique is a sensitive, simple and efficient method for distinguishing homologous transcripts in a mixed RNA population and can be applied to many types of studies on expression of homologous genes.
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  • 90
    ISSN: 1573-5028
    Keywords: Calvin cycle genes ; gene expression ; SBPase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here the isolation and nucleotide sequence of genomic clones encoding the chloroplast enzyme sedoheptulose-1,7-bisphosphatase (SBPase) from Arabidopsis thaliana. The coding region of this gene contains eight exons (72–76 bp) and seven introns (75–91 bp) and encodes a polypeptide of 393 amino acids. Unusually, the 5′ non-coding region contains two additional AUG codons upstream of the translation initiation codon. A comparison of the deduced Arabidopsis and wheat SBPase polypeptide sequences reveals 78.6%, identity. Expression studies showed that the level of SBPase mRNA in Arabidopsis and wheat is regulated in a light-dependent manner and is also influenced by the developmental stage of the leaf. Although the Arabidopsis SBPase gene is present in a single copy, two hybridizing transcripts were detected in some tissues, suggesting the presence of alternate transcription start sites in the upstream region.
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  • 91
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; Brassica napus ; gene expression ; Nicotiana tabacum ; retrotransposon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of the tobacco (Nicotiana tabacum) retrotransposon Tntl has previously been shown to be strongly regulated and driven from the 5′ long terminal repeat (LTR). We report here that the Tntl LTR can promote activity of the β-glucuronidase (GUS) reporter gene in two heterologous species of the Brassicaceae family, namely rapessed (Brassica napus) and Arabidopsis thaliana. The translational LTR-GUS fusion was active in transient expression studies performed with tobacco and rapeseed protoplasts, indicating that the LTR sequences are recognized in heterologous species. Our results also showed that Tntl LTR-promoted GUS expression in transgenic Arabidopsis is strongly regulated, and that, in contrast to tobacco, hormonal activation plays a significant role in the expression of the Tntl LTR in Arabidopsis. LTR sequences were shown to be more effective than the CaMV 35S enhancer region in transient expression studies performed with tobacco or rapessed protoplasts; and substitution of the LTR sequences upstream from the major transcriptional start with the CaMV 35S enhancer region gave high levels of expression in transgenic tobacco and Arabidopsis leaves, suggesting that a Tntl element with similar substitutions in its 5′ LTR might be suited for gene-tagging experiments in heterologous species.
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  • 92
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    Plant molecular biology 26 (1994), S. 617-630 
    ISSN: 1573-5028
    Keywords: ABA ; barley ; gene expression ; Hordeum vulgare ; phylogeny ; stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A single-copy barley gene, HVA1, encoding a class 3 late embryogenesis-abundant protein, can be induced by either treatment with abscisic acid (ABA) or by stress conditions such as drought, cold, heat and salinity. We have isolated an HVA1 genomic clone containing about 400 bp of 5′-upstream sequence, a single 109 bp intron, and the full coding sequence. Linker scan mutagenesis and transient expression studies were used to test the function of four HVA1 promoter elements conserved in ABA-responsive genes. Mutations in two of these elements, the C box and the putative ABRE 1 (ABA-responsive element) containing an ACGT core, resulted in no significant change in transcription level or ABA induction. In contrast, mutations of the other two elements, putative ABRE 2 & 3 cause the level of transcription to drop to 10–20% of that obtained with the wild-type promoter indicating that the high level of expression of HVA1 is dependent on both pABRE 2 & 3. Interestingly, despite their low level of expression, the mutated promoters still gave more than 20-fold induction in response to ABA treatment. We suggest that the ABA induction of barley HVA1 gene is governed by a complex consisting of pABRE 2 & 3 working together to regulate the absolute level of expression, and either of these elements or a possible third element may regulate ABA inducibility. Phylogenetic analysis by parsimony indicates that the barley HVA1 and wheat pMA2005 sequences share a recent common ancester. These two genes are closely related to the carrot Dc3 and cotton D-7 genes with which they share a similar structural gene organization.
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  • 93
    ISSN: 1573-5028
    Keywords: gene expression ; Kunitz-type proteinase inhibitor ; potato (Solanum tuberosum, L.) ; soybean C-II inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Antiserum against a potato Kunitz-type proteinase inhibitor (PKPI) expressed in Escherichia coli was produced. In immunoblotting assays of proteins from potato tubers cultured in vitro, three proteins reacted to the antiserum, two of 20 kDa and one of 10 kDa. Their N-termini were sequenced. While the 20 kDa proteins showed 59 and 90% identity to PKPI, the 10 kDa one had 65% identity to soybean C-II proteinase inhibitor. Characterization of the temporal expression of these proteins showed that both could be detected from 10 days after induction of tuberization (DAI) in vitro, but the times when maximum amounts of PKPI and 10 kDa protein could be detected were different, corresponding to 22 and 32 DAI, respectively. The amounts of these proteins decreased in the following stages, and no positive reaction of the antiserum with mature tuber proteins could be found. The 20 kDa proteins were also detected in early stages of development of potato tubers grown in the field, indicating that these proteins are expressed during normal tuber development, and differ from the PKPIs reported previously.
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  • 94
    ISSN: 1573-5028
    Keywords: anthocyanins ; cDNA cloning ; flavonoids ; gene expression ; genomic organization ; stilbenes ; Vitis vinifera L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genes involved in flavonoid and stilbene biosynthesis were isolated from grape (Vitis vinifera L.). Clones coding for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydoxylase (F3H), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX) and UDP glucose:flavonoid 3-O-glucosyl transferase (UFGT), were isolated by screening a cDNA library, obtained from mRNA from seedlings grown in light for 48 h using snapdragon (Antirrhinum majus) and maize heterologous probes. A cDNA clone coding for stilbene synthase (StSy) was isolated by probing the library with a specific oligonucleotide. These clones were sequenced and when the putative products were compared to the published amino acid sequence for corresponding enzymes, the percentages of similarity ranged from 65% (UFGT) to 90% (CHS and PAL). The analysis of the genomic organization and expression of these genes in response to light shows that PAL and StSy genes belong to large multigene families, while the others are present in one to four copies per haploid genome. The steady-state level of mRNAs encoded by the flavonoid biosynthetic genes as determined in young seedlings is coordinately induced by light, except for PAL and StSy, which appear to be constitutively expressed.
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  • 95
    ISSN: 1573-5028
    Keywords: cDNA sequence ; cystine-rich proteins ; gene expression ; puroindolines ; tryptophan-rich domain ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From a mid-maturation seed cDNA library we have isolated cDNA clones encoding two Triticum aestivum puroindolines. Puroindoline-a and puroindoline-b, which are 55% similar, are basic, cystine-rich and tryptophan-rich proteins. Puroindolines are synthezised as preproproteins which include N- and C-terminal propeptides which could be involved in their vacuolar localization. The mature proteins have a molecular mass of 13 kDa and a calculated isoelectric point greater than 10. A notable feature of the primary structure of puroindolines is the presence of a tryptophan-rich domain which also contains basic residues. A similar tryptophan-rich domain was found within an oat seed protein and a mammalian antimicrobial peptide. The ten cysteine residues of puroindolines are organized in a cysteine skeleton which shows similarity to the cysteine skeleton of other wheat seed cystine-rich proteins. Northern blot analysis showed that puroindoline genes are specifically expressed in T. aestivum developing seeds. No puroindoline transcripts as well as no related genes were detected in Triticum durum. The identity of puroindolines to wheat starch-granule associated proteins is discussed as well as the potential role of puroindolines in the plant defence mechanism.
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  • 96
    ISSN: 1573-5028
    Keywords: aspartate aminotransferase ; C4 photosynthesis ; gene expression ; gene structure ; isozyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cytosolic and mitochondrial isozymes of aspartate aminotransferase (AspAT) function in the C4 photosynthetic cycle in NAD-malic enzyme-type C4 plants and are expressed at high levels in mesophyll cells and bundle sheath cells, respectively. We constructed a genomic library from Panicum miliaceum, a NAD-malic enzyme-type C4 plant, and cloned the genes for these isozymes. The sequence of the cloned gene for cytosolic AspAT spans 7800 bp and consists of 12 exons. The sequence of the cloned gene for mitochondrial AspAT spans 9000 bp and consists of 10 exons. The results of primer-extension analysis suggest that transcription may be initiated from multiple adjacent sites. Both genes have significant GC-rich regions around the site of initiation of transcription, and these regions showed no CpG suppression. The 5′-flanking regions of both genes include several short sequences similar to the regulatory elements found in other genes for components of the photosynthetic machinery. In particular, the cytosolic AspAT gene contains sequences similar to nuclear protein-binding sites in other mesophyll-expressed C4 photosynthetic genes and the mitochondrial AspAT gene contains elements for light-sensitive and constitutive expression of a bundle sheath-expressed gene. The results of Southern analysis indicated that there are at least two genes that encode each isozyme in the genome of P. miliaceum. A comparison of nitron-insertion positions between AspAT genes of plants and animals revealed that several introns are located at identical positions. On the basis of a phylogenetic tree among AspATs and tyrosine aminotransferase, we have shown that the introns of aminotransferase genes antedate the divergence of eubacteria, archaebacteria, and eukaryotes.
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  • 97
    ISSN: 1573-5028
    Keywords: activating sequence ; gene expression ; glycine-rich protein ; tobacco ; vascular expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The bean grp1.8 full-length promoter is specifically active in vascular tissue during normal development of tobacco. Deletion of a negative regulatory element resulted in ectopic activity of the promoter in cortical cells of hypocotyls, roots and stems. A 169 bp fragment (−205 to −36) of the grp1.8 promoter conferred vascular-specific expression to CaMV 35S minimal promoters whereas a 141 bp fragment (−205 to −64) strongly activated these minimal promoters both in vascular and cortical cells. These experiments defined a new regulatory element (VSE) that is essential for vascular-specific expression and is located between −64 and −36. The 141 bp grp1.8 promoter sequence had enhancer-like properties as it was active in both orientations. A 24 bp sequence (bp −119 to −96, corresponding to the SE1 regulatory element) enhanced expression from several minimal promoters strongly but unspecifically, whereas a 26 bp sequence (−98 to −73, corresponding to the RSE regulatory element) induced vascular-specific expression. Thus, the grp1.8 promoter is regulated by a combinatorial mechanism that can integrate the action of different, non-additively acting regulatory elements into vascular-specific expression.
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  • 98
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    Plant molecular biology 26 (1994), S. 805-816 
    ISSN: 1573-5028
    Keywords: Dehydrin ; gene expression ; pea (Pisum sativum L.) ; cognate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dehydrins are a family of proteins characterised by conserved amino acid motifs, and induced in plants by dehydration or treatment with ABA. An antiserum was raised against a synthetic oligopeptide based on the most highly conserved dehydrin amino acid motif, the lysine-rich block (core sequence KIKEK-LPG). This antiserum detected a novel M r 40 000 polypeptide and enabled isolation of a corresponding cDNA clone, pPsB61 (B61). The deduced amino acid sequence contained two lysine-rich blocks, however the remainder of the sequence differed markedly from other pea dehydrins. Surprisingly, the sequence contained a stretch of serine residues, a characteristic common to dehydrins from many plant species but which is missing in pea dehydrin. The expression patterns of B61 mRNA and polypeptide were distinctively different from those of the pea dehydrins during seed development, germination and in young seedlings exposed to dehydration stress or treated with ABA. In particular, dehydration stress led to slightly reduced levels of B61 RNA, and ABA application to young seedlings had no marked effect on its abundance. The M r 40 000 polypeptide is thus related to pea dehydrin by the presence of the most highly conserved amino acid sequence motifs, but lacks the characteristic expression pattern of dehydrin. By analogy with heat shock cognate proteins we refer to this protein as a dehydrin cognate.
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  • 99
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    Plant molecular biology 26 (1994), S. 1529-1555 
    ISSN: 1573-5028
    Keywords: gibberellin ; growth ; development ; perception ; receptor ; gene expression ; signal transduction ; response mutant ; calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 100
    ISSN: 1573-5028
    Keywords: β-tubulin ; cDNA ; rice ; monocot ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two cDNA clones encoding two different β-tubulins, RTUB-1 and RTUB-2, were isolated from a rice cDNA library and their nucleotide sequences were analyzed. The deduced amino acid sequences showed amino acid sequence identity between 92% and 97% with other plant β-tubulins. Southern blot analysis using gene-specific and coding-region probes suggested that β-tubulins in rice are encoded by multigene families. The two cDNA clones represent two subfamilies of rice tubulins. RTUB-1 and RTUB-2, consisting of 3 to 4 genes and a single gene, respectively. The transcript levels of RTUB-1 and RTUB-2 genes were higher in actively elongating tissues such as etiolated shoot tissues and light-grown root tissues of four-day old seedlings.
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