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At least 811 records · Page 45Linked to original sources
PubMed2005

Resolution of sex chromosome constitution by genomic in situ hybridization and fluorescence in situ hybridization with (TTAGG)( n ) telomeric probe in some species of Lepidoptera.

We have developed a simple method to resolve the sex chromosome constitution in females of Lepidoptera by using a combination of genomic in situ hybridization (GISH) and fluorescence in situ hybridization with (TTAGG)( n ) telomeric probe (telomere-FISH). In pachytene configurations of sex chromosomes, GISH differentiated W heterochromatin and telomere-FISH detected the chromosome ends. With this method we showed that Antheraea yamamai has a standard system with a fully differentiated W-Z sex chromosome pair. In Orgyia antiqua, we confirmed the presence of neo-W and neo-Z chromosomes, which most probably originated by fusion of the ancestral W and Z with an autosome pair. In contrast to earlier data, Orgyia thyellina females displayed a neo-ZW(1)W(2) sex chromosome constitution. A neo-WZ(1)Z(2) trivalent was found in females of Samia cynthia subsp. indet., originating from a population in Nagano, Japan. Whereas another subspecies collected in Sapporo, Japan, and determined as S. cynthia walkeri, showed a neo-W/neo-Z bivalent similar to O. antiqua, and the subspecies S. cynthia ricini showed a Z univalent (a Z/ZZ system). The combination of GISH and telomere-FISH enabled us to acquire not only reliable information about sex chromosome constitution but also an insight into sex chromosome evolution in Lepidoptera.

Animals↗
PubMed2000

Constitutively activating TSH-receptor mutations as a molecular cause of non-autoimmune hyperthyroidism in childhood.

BACKGROUND: The glycoprotein hormone TSH (thyroid-stimulating hormone) and its receptor, the TSH-receptor (TSHR), play a crucial role in thyroid growth and function. Constitutively activating germline mutations within the TSHR gene were identified in patients with sporadic or familial non-autoimmune hyperthyroidism. Inheritance of these mutations is autosomal dominant. PATIENTS AND METHODS: We investigated two patients with neonatal onset of non-autoimmune hyperthyroidism and two families in whom the child and one parent are affected. RESULTS: Hyperthyroidism was difficult to treat in all of these patients and was complicated by premature craniosynostosis. Sequencing of all exons of the TSHR gene in one family with hyperthyroidism revealed a mutation in exon 10 (T6321), which was first identified in toxic adenomas and found to constitutively activate the TSHR. In the other family, we identified a new mutation in the first membrane spanning segment (G431S). In both patients with sporadic hyperthyroidism, a heterozygous mutation in exon 9 (S281N) was detected. The functional characterization of S281N and G431S demonstrated that both mutants were constitutively active. Therefore, these mutations are the molecular cause of non-autoimmune hyperthyroidism in the patients. CONCLUSIONS: For patients suffering from non-autoimmune hyperthyroidism, screening for mutations and their functional characterization is recommended. In case of an ineffective hyperthyroidism treatment, thyroidectomy should be performed to prevent lengthy anti-thyroid drug treatment and complications like premature craniosynostosis.

Child↗
PubMed2006

Constitutive knox1 gene expression in dandelion (Taraxacum officinale, Web.) changes leaf morphology from simple to compound.

Seed plants with compound leaves constitute a polyphyletic group, but studies of diverse taxa show that genes of the class 1 KNOTTED-LIKE HOMEOBOX (KNOX1) family are often involved in compound leaf development. This suggests that knox1 genes have been recruited on multiple occasions during angiosperm evolution (Bharathan et al. in Science 296:1858-1860, 2002). In agreement with this, we demonstrate that the simple leaf of dandelion (Taraxacum officinale Web.) can be converted into a compound leaf by the constitutive expression of heterologous knox1 genes. Dandelion is a rosette plant of the family Asteraceae, characterised by simple leaves with deeply lobed margins and endogenous knox1 gene expression. Transgenic dandelion plants constitutively expressing the barley (Hordeum vulgare L.) hooded gene (bkn3, barley knox3) or the related bkn1 gene, developed compound leaves featuring epiphyllous rosettes. We discuss these results in the context of two current models of compound leaf formation.

Gene Expression↗
PubMed1997

Constitutive and carbon source-responsive promoter elements are involved in the regulated expression of the Saccharomyces cerevisiae malate synthase gene MLS1.

The malate synthase gene, MLS1, of the yeast Saccharomyces cerevisiae is transcriptionally regulated by the carbon source in the growth medium. A MLS1-lacZ fusion gene, expressed at a basal level in the presence of 2% glucose, is derepressed more than 100-fold under conditions of sugar limitation. No evidence for MLS1 induction by oleic acid was found. By deletion analysis of the MLS1 control region, we identified two sites, UAS1 and UAS2, as important for efficient derepression of the gene. Both sites contain sequences that resemble the previously characterized carbon source-responsive element (CSRE) found in the promoter of the isocitrate lyase gene ICL1. Indeed, UAS1 and UAS2 in the MLS1 upstream region turn out to be functional CSRE sequence variants. This finding allowed us to define a modified version of the CSRE consensus sequence (CCRTYSRNCCG). Protein binding to UAS1MLS1 was observed with extracts from derepressed but not from repressed cells, and could be competed for by an excess of the unlabelled CSRE (ICL1) sequence. No competition was observed with a mutated CSRE variant. Site-directed mutagenesis of both CSREs in the MLS1 promoter reduced gene activation under derepressing conditions to 20% of the wild-type level. The same decrease was observed with the wild-type MLS1 promoter in a cat8 mutant, lacking an activator of CSRE-dependent transcription. The CSRE/Cat8p-independent activation of MLS1 is mediated by constitutive UAS elements. The pleiotropic transcription factor Abf1p, which binds to the MLS1 upstream region, may contribute to constitutive activation. Thus, in order to ensure the severe glucose repression of MLS1 observed, repressor elements that respond to the carbon source must counteract constitutive activation. In summary, ICL1 and MLS1 share common cis-acting elements, although a distinct mechanism of carbon source control also contributes to MLS1 regulation.

Amino Acid Sequence↗
PubMed2006

A constitutive law for the failure behavior of medial collateral ligaments.

A constitutive model is proposed for the description of the tensile properties of medial collateral ligaments (MCLs). The model can reproduce the three regions -- the toe region, the linear region, and the failure region -- of the stress-stretch curve of ligamentous tissues. The collagen fibers are assumed to be the only load-bearing component of the tissues. They are all oriented along the physiological loading direction of the ligament. They are crimped in the slack configuration and are unable to sustain load. After becoming taut and before failing, each collagen fiber exhibits a linear elastic behavior. The fiber straightening and failure processes are defined stochastically by means of Weibull distributions. Published experimental data for the MCLs are employed to validate the constitutive relationship. Finally, the constitutive model is generalized in order to describe the three-dimensional mechanical behavior of the ligaments by following he structural approach.

Algorithms↗
PubMed2006

Angiographic segment size in patients referred for coronary intervention is influenced by constitutional, anatomical, and clinical features.

BACKGROUND: Factors influencing the size of target vessels of patients referred for coronary intervention are poorly defined. We aimed to investigate in a large series of patients undergoing percutaneous intervention the relation of constitutional, anatomical, and clinical features with the reference diameter of coronary vessels treated with stenting. METHODS: A total of 4,850 de novo coronary lesions, non-ostial and non-bifurcational, located in native vessels were analyzed. The following pre-specified characteristics were analyzed to reflect the relation between constitutional, anatomical, and clinical features on reference vessel diameter: age, gender, height, weight, proximal location, vessel, diabetes, hypertension, multivessel disease, and clinical presentation. RESULTS: The average reference diameter was 2.66+/-0.50 mm. All pre-specified markers had a significant relation with the vessel reference diameter at univariate analysis, except by hypertension which showed a strong tendency. However, at multivariate analysis, only diabetes, proximal location, multivessel disease, clinical presentation, vessel, weight, and height were identified as independent predictors of reference vessel diameter. CONCLUSION: Reference diameter of coronary vessels at the site of lesions treated by stenting is significantly influenced by a variety of characteristics. We hypothesize that the treated segment size of patients undergoing stenting ultimately reflects the conjoint effect of several different factors, including constitutional, anatomical, and clinical features.

Angioplasty, Balloon, Coronary↗
PubMed2006

New constitutionalism and the social reproduction of caring institutions.

This essay analyzes neo-liberal economic agreements and legal and political frameworks or what has been called the "new constitutionalism," a governance framework that empowers market forces to reshape economic and social development worldwide. The article highlights some consequences of new constitutionalism for caring institutions specifically, and for what feminists call social reproduction more generally: the biological reproduction of the species; the reproduction of labor power; and the reproduction of social institutions and processes associated with the creation and maintenance of communities. New constitutional governance frameworks fundamentally reshape conditions under which the care of human beings takes place. Caring institutions once governed by enabling professions geared to universal care are now determined increasingly by market values and private forces, and driven directly by the profit motive. This is one of the reasons why neo-liberalism is increasingly contested in both the North and the global South.

Commerce↗
PubMed2005

Mitochondrial functioning of constitutive iron uptake mutations in Cryptococcus neoformans.

Randomly obtained, constitutive plasma membrane ferric reductase/ferrous uptake mutants of Cryptococcus neoformans were mapped to four distinct loci by meiotic analysis. One of those loci, FRR1 , was previously found homologous to MRS3 and MRS4 of Saccharomyces cerevisiae , which determine proteins involved in mitochondrial transport of iron. We were able to complement, clone, sequence and thereby identify two of the three remaining constitutive uptake loci. FRR3 was found to be homologous to ISU1 and ISU2 of S. cerevisiae, which form mitochondrial iron-sulfur complexes; FRR4 was found to be homologous to YFH1, the yeast frataxin homologue, which also participates in iron-sulfur cluster biogenesis. Because of the constitutive iron uptake seen in these mutants, mitochondria appear to have a central role in the cellular iron economy; moreover, as judged by our mutational statistics, the genetic machinery for mitochondrial iron accumulation may be more complex than that of the cytoplasm.

Amino Acid Sequence↗
PubMed2004

Constitutive expression of pea Lhcb 1-2 in tobacco affects plant development, morphology and photosynthetic capacity.

Lhcb1-2 from pea was constitutively expressed in transgenic tobacco plants and assessed for functional impact. The successful assembly of the encoded proteins into LHCII trimers was confirmed by electrospray tandem mass spectrometry. Constitutive production of LHCb1-2 led to increased number of thylakoid membranes per chloroplast, increased grana stacking, higher chloroplast numbers per palisade cell and increased photosynthetic capacity at low irradiance, both on a chlorophyll and leaf area basis. The transgenic plants also displayed increased cell volume, larger leaves, higher leaf number per plant at flowering, increased biomass and increased seed weight, when grown under low irradiance levels. Under high irradiance, both transgenic and wild type plants displayed similar photosynthetic rates when tested at 25 degrees C; however, the non-photochemical quenching (NPQ) and qE values increased in the transgenic plants. The exposure of transgenic plants to a photoinhibitory treatment (4 degrees C for 4 h, under continuous illumination) resulted in more detrimental impairment of photosynthesis, since recovery was slower than the non-transgenic plants. These data indicate that constitutive expression of additional Lhcb1-2 transgenes led to a series of changes at all levels of the plant (cellular, leaf and whole organism), and a delay in flowering and senescence. The additional production of the pea protein appears to be accommodated by increasing cellular structures such as the number of thylakoids per chloroplast, organelle volume, organelles per cell, and leaf expansion. The presence of the trimeric pea protein in the tobacco LHCII, however, caused a possible change in the organization of the associated super-complex, that in turn limited photosynthesis at low temperature.

Amino Acid Sequence↗
PubMed2004

Temporally regulated expression of a yeast invertase in potato tubers allows dissection of the complex metabolic phenotype obtained following its constitutive expression.

The constitutive cytosolic expression of a yeast ( Saccharomyces cerevisiae ) invertase within potato ( Solanum tuberosum ) tubers has previously been documented to produce a dramatic metabolic phenotype in which glycolysis, respiration and amino acid synthesis are markedly enhanced at the cost of starch synthesis. These transgenic lines were further characterised by a massive cycle of sucrose degradation and resynthesis via sucrose-phosphate synthase. We have recently developed a B33 patatin driven alc gene construct allowing tight chemical control of gene expression following supply of acetaldehyde with minimal pleiotropic effects of the inducing agent on metabolism. This construct was used for chemical induction of the yeast invertase gene after 10-weeks growth to dissect the complex metabolic phenotype obtained after constitute expression. Inducible expression led to increased invertase activity within 24 h in well-defined areas within growing tubers. Although the sucrose levels were reduced, there was no effect on the levels of starch whilst levels of many amino acids decreased. Labelling experiments revealed that these lines exhibited increased rates of sucrose cycling, whereas rates of glycolysis and of starch synthesis were not substantially changed. From these results we conclude that sucrose cycling is stimulated in response to a short-term increase in the rate of sucrose mobilisation, providing evidence for a role of sucrose cycling as a buffering capacity that regulates the net rate of sucrose usage. In contrast, the dramatic increase in hexose-phosphate levels and the switch from starch synthesis to respiration seen on the constitutive expression of the invertase was not observed in the inducible lines, suggesting that this is the result of cumulative pleiotropic effects that occurred when the transgene was expressed throughout development.

Carbon Radioisotopes↗
PubMed2005

Characterization of a strong, constitutive mung bean (Vigna radiata L.) promoter with a complex mode of regulation in planta.

We report the cloning and characterization in tobacco and Arabidopsis of a Vigna radiata L. (mung bean) promoter that controls the expression of VR-ACS1, an auxin-inducible ACC synthase gene. The VR-ACS1 promoter exhibits a very unusual behavior when studied in plants different from its original host, mung bean. GUS and luciferase in situ assays of transgenic plants containing VR-ACS1 promoter fusions show strong constitutive reporter gene expression throughout tobacco and Arabidopsis development. In vitro quantitative analyses show that transgenic plants harboring VR-ACS1 promoter-reporter constructs have on average 4-6 fold higher protein and activity levels of both reporter genes than plants transformed with comparable CaMV 35S promoter fusions. Similar transcript levels are present in VR-ACS1 and CaMV 35S promoter lines, suggesting that the high levels of gene product observed for the VR-ACS1 promoter are the combined result of transcriptional and translational activation. All tested deletion constructs retaining the core promoter region can drive strong constitutive promoter activity in transgenic plants. This is in contrast to mung bean, where expression of the native VR-ACS1 gene is almost undetectable in plants grown under normal conditions, but is rapidly and highly induced by a variety of stimuli. The constitutive behavior of the VR-ACS1 promoter in heterologous hosts is surprising, suggesting that the control mechanisms active in mung bean are impaired in tobacco and Arabidopsis. The 'aberrant' behavior of the VR-ACS1 promoter is further emphasized by its failure to respond to auxin and cycloheximide in heterologous hosts. VR-ACS1 promoter regulatory mechanisms seem to be different from all previously characterized auxin-inducible promoters.

Arabidopsis↗
PubMed1995

Differential measurement of constitutive (COX-1) and inducible (COX-2) cyclooxygenase expression in human umbilical vein endothelial cells using specific immunometric enzyme immunoassays.

We have produced and characterized monoclonal antibodies (mAbs) directed against a specific carboxyterminal sequence of human cyclooxygenase-2 (residues 580-598). A rabbit polyclonal antiserum was also raised against another sequence of 10 amino acids (residues 570-581) not present in human constitutive cyclooxygenase-1. Affinity-purified polyclonal antibodies, coated on microtiter plates, were used as capture antibodies in a two-site immunometric assay, with an mAb-acetylcholinesterase conjugate used as tracer. The detection limit was 500 fmol/ml of peptide C3-COX2 (residues 570-595). The assay was specific for the cyclooxygenase-2 (COX-2) isoform, since no immunoreactivity could be detected in platelet extracts known to be rich in cyclooxygenase-1 (COX-1). In contrast, extracts from cultured human umbilical vein endothelial cells challenged with 20 nM phorbol myristate acetate (PMA) showed an increase in COX-2 immunoreactivity related both to the increase in enzyme activity and the variations observed by Western blot analysis. Under these conditions, analysis of the same cell lysates with another immunometric assay specific for COX-1 revealed insignificant variation of this enzyme. The specificity of detection was further assessed by measuring the immunoreactivity of the fractions obtained after molecular sieve chromatography of control and stimulated cell extracts, and corroborated the marked enhancement of COX-2 by comparison with COX-1. Treatment of PMA-activated cells with H-7 or actinomycin D totally abolished the COX-2 signal and had little effect on COX-1. No significant variation in COX-2 immunoreactivity was observed using the inactive isomer 4 alpha-PMA, even at 100 nM. These assays constitute the first quantitative analysis of constitutive COX-1 and of inducible COX-2 in nucleated cells at the protein level.

Amino Acid Sequence↗
PubMed1977

Genetic regulation of the constitutive D-ribose operon in Escherichia coli B/r.

Merodiploid complementation analysis of the constitutive synthesis of the D-ribokinase and the D-ribose permease in Escherichia coli B/r has shown that the constitutive D-ribose operon is genetically controlled by a transdominant regulatory gene closely linked to the D-ribokinase and D-ribose permease structural genes. The regulatory mechanism for this operon shows no requirement for operator-repressor interaction, rather a truly positive control mechanism and thus suggests an extension of the operon model in its application to constitutive enzyme regulation in bacteria.

Chromosome Mapping↗
PubMed1992

Constitutive expression of c-fos gene inhibits type 1 collagen synthesis in transfected osteoblasts.

To clarify the contribution of c-fos DNA to bone formation, the effect of constitutive expression of the c-fos gene in collagen synthesis was examined by introducing c-fos DNA into osteoblastic MC3T3-E1 cells. The [3H] proline incorporation into the collagenase digestible protein(CDP) and the percent collagen synthesis were significantly decreased in the c-fos transfectants which constitutively express c-fos mRNA as compared with control transfectants. Transcription of type 1(alpha 1) collagen gene was also specifically decreased in the c-fos transfectants. This indicates that constitutive expression of c-fos DNA interferes with bone formation by inhibiting collagen synthesis in osteoblasts.

Animals↗
PubMed1989

Selective alteration of constitutive hepatic cytochrome P-450 enzymes in the rat during parenteral hyperalimentation.

Decreased drug metabolism and hepatic cytochrome P-450 levels have been shown previously to occur in rats receiving total parenteral nutrition (TPN) compared to animals receiving the same hyperalimentation solution enterally (TEN). In the present studies, animals received a 7-day infusion of a 25% glucose-2.75% crystalline amino acid solution via a catheter in the jugular vein or stomach; hepatic microsomal levels of four major constitutive cytochromes P-450 were determined subsequently by immunoquantitation and correlated with metabolism of selected substrates biotransformed by these enzymes. TPN resulted in a marked decrease in apoprotein of two constitutive cytochromes P-450, P-450UT-A and P-450PCN-E, compared to TEN experiments (for P-450UT-A, 11.0 +/- 1.8 vs 44.7 +/- 6.5% of total cytochrome P-450 measured by CO-difference spectra, P greater than 0.001; for P-450PCN-E, 15.4 +/- 4.4 vs 30.2 +/- 7.6%, P less than 0.01), but apoprotein levels of two other constitutive cytochromes P-450, P-450PB-C and P-450UT-F, showed relatively little change. Concordant reductions in metabolism of benzphetamine, ethylmorphine and erythromycin were seen in TPN animals. While the mechanisms responsible for these selective changes in the synthesis and function of individual cytochromes P-450 remain to be elucidated, altered gene transcription due to differences in portal blood composition elicited by intravenous versus enteral feeding is a possible hypothesis. These studies also provide information which should be valuable in designing studies to probe further the clinical question of whether TPN induces significant alterations in human drug metabolism.

Animals↗
PubMed1994

Tissue-specific constitutive and inducible expression of rat phenol UDP-glucuronosyltransferase.

To investigate constitutive and inducible expression of rat phenol UDP-glucuronosyltransferase (UGT1A1) in liver and extrahepatic tissues, a selective cDNA probe for its unique exon 1 was utilized. 6-Hydroxychrysene was used as a functional probe of UGT1A1 activity. Constitutive expression of UGT1A1 was low in liver, but high in kidney, testis, epididymis and ovary. After treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 10 micrograms/kg for 7 days) the UGT1A1 mRNA level was markedly increased in liver (ca. 10-fold), and only moderately enhanced (up to 2-fold) in extrahepatic tissues where constitutive enzyme expression was high. UGT activity toward 6-hydroxychrysene was strongly inducible in liver (ca. 9-fold) and only moderately inducible in extrahepatic tissues (up to 2-fold). The results suggest complex tissue-specific regulation of UGT1A1 including positive and negative transcriptional factors and marked inducibility by TCDD in liver.

Animals↗
PubMed1990

Biosynthesis of peptide precursors and protease inhibitors using new constitutive and inducible eukaryotic expression vectors.

A series of expression vectors has been constructed as based on the pML derivative of pBR322. The eukaryotic transcription units employ various promoters followed by polycloning sites for 3-9 commonly used restriction enzymes and are completed by the SV40 polyadenylation sequence. In 4 of the vectors, designed for co-transfection or transient expression studies, only a single transcription unit containing either a constitutive or an inducible promoter was incorporated. The human ubiquitin (UbC) promoter was used as a strong constitutive promoter, while the mouse metallothionein promoter and the promoter of the long terminal repeats of the mouse mammary tumor virus were used as inducible promoters. Another vector contained an additional transcription unit encoding a eukaryotic selection marker, the neomycin resistance encoding gene. The vectors were used in CHO cells and in neuroendocrine CA77 cells to synthesize peptide precursors, protease inhibitors and a protease. It is shown that these vectors are very efficient for the constitutive and inducible expression of nucleotide sequences in both transient and stable transfections of eukaryotic cells.

Animals↗
PubMed1993

Positional and additive effects of basic amino acids on processing of precursor proteins within the constitutive secretory pathway.

We have recently shown that the Arg/Lys-X-Lys/Arg-Arg or Arg/Lys-X-X-X-Lys/Arg-Arg sequence serves as a signal for cleavage of precursor proteins within the constitutive secretory pathway, and this cleavage is catalyzed by furin, a mammalian homolog of the yeast Kex2 protease. In this study, we further examined sequence requirements for the constitutive precursor cleavage. Based on the data concerning cleavage efficiencies of various prorenin mutants with amino acid substitution(s) around the native cleavage site expressed in CHO cells, we revised the sequence rules that govern the constitutive cleavage as follows: (i) the Arg residue at position -1 is essential; (ii) in addition to the Arg at position -1, at least two out of the three basic residues at positions -2, -4, and -6 are required for efficient cleavage (the presence of all the three basic residues results in most efficient cleavage); (iii) at position +1, a hydrophobic aliphatic amino acid is not suitable.

Amino Acid Sequence↗