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E Remy

Publications and source records attributed to E Remy.

12 recordsLinked to original sources
PubMed2005

Qualitative modelling of regulated metabolic pathways: application to the tryptophan biosynthesis in E.coli.

MOTIVATION: The integrated dynamical modelling of mixed metabolic/genetic networks constitutes one of the challenges of systems biology. Furthermore, as most of available data about genetic and metabolic regulations are qualitative, there is a pressing need for rigorous qualitative mathematical approaches. RESULTS: On the basis of two established formalisms, the logical modelling of genetic regulatory networks and the Petri net modelling of metabolic networks, we propose a systematic approach for the modelling of regulated metabolic networks. This approach leans on previous work defining a systematic procedure to translate logical regulatory graphs into standard (discrete) Petri nets (PNs). This approach is illustrated by the qualitative modelling of the biosynthesis of tryptophan (Trp) in Escherichia coli, taking into account two types of regulatory feedbacks: the direct inhibition of the first enzyme of the pathway by the final product of the pathway, and the transcriptional inhibition of the Trp operon by the Trp-repressor complex. On the basis of this integrated PN model, we further indicate how available dynamical analysis tools can be applied to obtain significant insights in the behaviour of the system. AVAILABILITY: The software GINsim for the logical modelling of genetic regulatory networks together with the PN model of the regulated Trp biosynthesis pathway are available at: http://gin.univ-mrs.fr/GINsim.

Computer Simulation↗
PubMed2003

A description of dynamical graphs associated to elementary regulatory circuits.

The biological and dynamical importance of feedback circuits in regulatory graphs has often been emphasized. The work presented here aims at completely describing the dynamics of isolated elementary regulatory circuits. Our analytical approach is based on a discrete formal framework, built upon the logical approach of R. Thomas. Given a regulatory circuit, we show that the structure of synchronous and asynchronous dynamical graphs depends only on the length of the circuit (number of genes) and on its sign (which depends on the parity of the number of negative interactions). This work constitutes a first step towards the analytical characterisation of discrete dynamical graphs for more complex regulatory networks in terms of contributions corresponding to their embedded elementary circuits.

Algorithms↗
PubMed1998

The annealing of tRNA3Lys to human immunodeficiency virus type 1 primer binding site is critically dependent on the NCp7 zinc fingers structure.

The nucleocapsid protein NCp7 of the human immunodeficiency virus type 1 contains two zinc fingers of the CX2CX4HX4C type, flanked by several basic residues, and plays a major role in viral infectivity. Thus, NCp7 was shown to promote annealing of the tRNA3Lys to the primer binding site, a key step in reverse transcription. However, previous in vitro experiments were unable to clarify the role of the zinc fingers in this process, due to nucleic acid aggregation induced by the basic N- and C-terminal domains of NCp7. We show here that deletion of these sequences in (12-53)NCp7 strongly reduces the formation of aggregates and allows a direct visualization of the binary or ternary complexes between NCp7 and nucleic acids by gel electrophoresis. (12-53)NCp7 is able to induce hybridization of the 33P tRNA3Lys and the human immunodeficiency virus type 1 viral RNA-(77-257), which contains the primer binding site. Modification of the proximal zinc finger conformation in Cys23(12-53)NCp7 led to a large reduction in this hybridization process, while replacement of Trp37 by Leu in the distal zinc fingers resulted in a complete absence of annealing activity. These data account for the in vivo loss of viral infectivity following these mutations and emphasize the critical role of the structure of the zinc finger domain of NCp7. This could facilitate a rational approach to new antiviral agents directed toward NCp7.

Amino Acid Sequence↗
PubMed1998

Asymmetry correction equations for hand volume, grip and pinch strengths in healthy working people.

Assessments of oedema and decrease in hand strength are useful for patients with a hand lesion. This study examined the asymmetry of the arms and determined the estimates of the unknown prior to lesion values for hand volume, grip strengths assessed with a Jamar dynamometer (GS[J]) and a Collins dynamometer (GS[C]), and pinch strength with a Jamar pinch gauge (PS) in 100 healthy working people. Hand volume, GS(J), GS(C) and PS of the dominant hand were respectively 3.6 +/- 4.1%, 6.6 +/- 9.2%, 11.7 +/- 11.2%, and 8.0 +/- 13.2% higher than those of the non-dominant hand (p < 0.001). Very good estimates were obtained with the values of the contralateral arm for all the indices studied. The correlation coefficient equalled 0.95 for hand volume, 0.91 for GS(J), 0.83 for GS(C), and 0.72 for PS. These estimates allow us to evaluate the evolution of oedema and hand strengths in patients with hand injury, especially to determine whether they could return to work as they are mostly manual workers with demanding jobs.

Adolescent↗
PubMed1997

Comparison between estimates of hand volume and hand strengths with sex and age with and without anthropometric data in healthy working people.

Edema and hand strength measurements are useful for the recovery assessment of patients with a hand lesion. This work determined and compared estimates of hand volume, grip strengths (measured with a Jamar and a Collins dynamometer), and pinch strength (with a Jamar pinch gauge) in terms of sex and age with or without anthropometric indices in healthy working people. The sample included 100 subjects from within the staffs of two rehabilitation centres. For both grip strengths, multiple linear regression models including body height, weight, and arm muscle area were very good (multiple correlation coefficient R of about 0.84) and clearly better than those obtained with sex and age only. For pinch strength, the best estimate was obtained with sex and arm muscle area (R of 0.76); for hand volume, the model with sex, body height, and weight provided the best result (R of 0.93). These findings suggested that anthropometric indices easy to measure must be taken into account to estimate hand volume and hand strengths.

Adult↗
PubMed1992

Cloning, expression, and nucleotide sequence of glgC gene from an allosteric mutant of Escherichia coli B.

The Escherichia coli B mutant strain CL1136 accumulates glycogen at a 3.4- to 4-fold greater rate than the parent E. coli B strain and contains an ADPglucose synthetase with altered kinetic and allosteric properties. The enzyme from CL1136 is less dependent on the allosteric activator, fructose 1,6-bisphosphate, for activity and less sensitive to inhibition by AMP than the parent strain enzyme. The structural gene, glgC, for the allosteric mutant enzyme was selected by colony hybridization and cloned into the bacterial plasmid pBR322 by insertion of the chromosomal DNA at the PstI site. One recombinant plasmid, designated pKG3, was isolated from the genomic library of CL1136 containing glgC. The cloned ADPglucose synthetase from the mutant CL1136 was expressed and characterized with respect to kinetic and allosteric properties and found to be identical to the enzyme purified from the CL1136 strain. The mutant glgC was then subcloned into pUC118/119 for dideoxy sequencing of both strands. The mutant glgC sequence was found to differ from the wild-type at the deduced amino acid residue 67 where a single point mutation resulted in a change from arginine to cysteine.

Allosteric Regulation↗
PubMed1989

Inhibition of platelet-activating factor biosynthesis via the acetyltransferase by arachidonic and oleic acids in ionophore A23187-stimulated bovine neutrophils.

Platelet-activating factor (PAF) is a phospholipid mediator of inflammation and allergy that is synthesized by several inflammatory cells including neutrophils. Addition of exogenous arachidonic acid to ionophore A23187-stimulated bovine neutrophils led to the inhibition of PAF biosynthesis assayed by incorporation of [3H]acetate into PAF and by bioassay; under the same conditions, leukotriene B4 (LTB4) formation was not decreased. The activities of the PAF metabolism enzymes indicated that the PAF synthesis inhibition by arachidonic acid is mediated via the acetyltransferase inhibition which is the last enzyme of the PAF formation. Another unsaturated fatty acid, oleic acid, exhibited the same inhibitory effect on [3H]acetate-PAF formation; however, the saturated stearic acid did not lead to any inhibition. These findings suggest that liberation of unsaturated fatty acids from membrane phospholipids, as a consequence of phospholipase A2 activation, would modulate PAF formation via inhibition of the acetyltransferase. In addition, the utilization of arachidonic acid oleic acids in activated neutrophils furnishes an easy means of blocking PAF synthesis in order to understand the role of this mediator in cellular processes.

Acetates↗
PubMed1976

The laser in the Lowry technique for microdissection of freeze-dried tissue slices.

A new technique for tissue microdissection is described. This procedure, using an u.v.-laser micropreparation instrument, overcomes the extremely time-consuming manual preparation. The u.v.-laser micropreparation design allows fast, precise, reproducible and smear-contamination-free tissue microdissection. The preparation of the tissue sample can be programmed by tracing out the area to be sampled with a non-destructive 0.5 mW He-Ne-laser aiming-beam. The tract is stored in a small electronic unit, which then guides the motor-driven stepping stage on the microscope in the actual dissection run with the u.v.-laser. The laser power is adjustable in the range 4 to 40 kW and controlled by a photo diode displayed on an oscilloscope screen. In the tissue slice, prepared according to Lowry, an unlimited number of cells or tissue compartments can be dissected and afterwards weighed. The procedure described offers a broader use of the quantitative microhistochemical techniques of Lowry and of Neuhoff.

Acid Phosphatase↗
PubMed1976

Cell surgery by laser micro-dissection: a preparative method.

A new UV-laser device is introduced as a micro-manipulator and micro-dissection apparatus for experimental cell research. High energy irradiation is produced by a quasi-continuous N2-laser. The laser micro-beam can be focused to a minimal diameter of 0-75 mum. The micro-laser can be used for cutting and, hence, as a micro-surgical instrument at the level of cellular organelles. Cytoplasmic actomyosin fibrils (AM fibrils) from tissue culture cells (RMCD-cells) are isolated from the surrounding ground cytoplasm. It is shown that the contractile proteins are not damaged by the laser dissection method to an extent that would prevent their normal function, e.g. contraction.

Actomyosin↗