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91.
Lignin genetic engineering 总被引:5,自引:0,他引:5
Alain M. Boudet Jacqueline Grima-Pettenati 《Molecular breeding : new strategies in plant improvement》1996,2(1):25-39
Although lignins play important roles in plants, they often represent an obstacle to the utilization of plant biomass in different areas: pulp industry, forage digestibility. The recent characterization of different lignification genes has stimulated research programmes aimed at modifying the lignin profiles of plants through genetic engineering (antisense and sense suppression of gene expression). The first transgenic plants with a modification of monomeric composition of lignins and lignin content have been recently obtained. Down regulation of the OMT gene induces dramatic reduction of syringyl units. CAD down regulated plants exhibit a unusual red phenotype associated with the developing xylem and several chemical modifications of their lignins including an increase in cinnamaldehydes in the polymer structure. Interestingly this novel lignin is removed more easily during the pulping process. In both OMT and CAD down regulated plants no changes in phenotypic characteristics such as growth architecture and morphology were observed. More recent experiments have shown that a reduction of CCR activity determines specific changes in the coloration of the xylem area suggesting significant chemical modifications which are currently being studied.These different results show that it is possible to manipulate lignins through targeted genetic transformation of plants and that lignins exhibit a relative flexibility of their chemical structure. Future developments should probe the impact of down regulating the expression of other recently characterized lignification genes such as F5H and CCoAOMT and also of a combination of genes in order to tailor lignins more adapted to specific purposes. In addition to biotechnological applications which should provide important economical benefits for utilization of wood in the pulp industry, genetic engineering of lignins offer very promising perspectives for the understanding of lignin synthesis, structure and properties. 相似文献
92.
Molecular analysis of the modulatory factors of the response to HBsAg in mice as an approach to HBV vaccine enhancement 总被引:1,自引:0,他引:1
Philippe Bouige Sylvio Iscaki Alain Cosson Jacques Pillot 《FEMS immunology and medical microbiology》1996,13(1):71-79
Abstract Mice were injected with immune complexes containing the recombinant hepatitis B surface antigen (HBsAg) vaccine (S + preS2) bound to different monoclonal antibodies (mAbs), in order to determine whether an enhancement of the response to a human vaccine could be obtained and observed. Enhancement and indifference were observed, as well as a decrease in immunogenicity. N relationship could be established between any effect and affinity or isotypy of the bound mAbs. The preS2 region was rendered more immunogenic when an IgG2a mAb was bound to the S region of the HBsAg. The response to the S region was not modulated, whereas immunogenicity of the preS2 collinear region was decreased by antibody shielding. The mAb which was the most efficient as an enhancer of the antibody response also increased binding of the complexed immunogen to antigen presenting cells. The binding of a human mAb to the sole S region, but not to the preS2 region, should be tested as a potentiating agent of the anti-preS2 human immune response. 相似文献
93.
94.
Further progress towards a catalogue of all Arabidopsis genes: analysis of a set of 5000 non-redundant ESTs 总被引:9,自引:1,他引:8
Richard Cooke Monique Raynal Michele Laudi Franoise Grellet Michel Delseny Peter-Christian Morris Danile Guerrier Jrme Giraudat Franoise Quigley Grard Clabault You-Fang Li Rgis Mache Micheline Krivitzky Isabelle Jean-Jacques Gy Martin Kreis Alain Lecharny Yves Parmentier Jacqueline Marbach Jacqueline Fleck Bernadette Clment Gabriel Philipps Christine Herv Claude Bardet Dominique Tremousaygue Bernard Lescure Christophe Lacomme Dominique Roby Marie-Franoise Jourjon Patrick Chabrier Jean-Louis Charpenteau Thierry Desprez Joelle Amselem Helen Chiapello Herman Hfte 《The Plant journal : for cell and molecular biology》1996,9(1):101-124
Nearly 7000 Arabidopsis thaliana -expressed sequence tags (ESTs) from 10 cDNA libraries have been sequenced, of which almost 5000 non-redundant tags have been submitted to the EMBL data bank. The quality of the cDNA libraries used is analysed. Similarity searches in international protein data banks have allowed the detection of significant similarities to a wide range of proteins from many organisms. Alignment with ESTs from the rice systematic sequencing project has allowed the detection of amino acid motifs which are conserved between the two organisms, thus identifying tags to genes encoding highly conserved proteins. These genes are candidates for a common framework in genome mapping projects in different plants. 相似文献
95.
96.
Mohamed Benichou Gracia Martinez-Reina Felix Romojaro Jean-Claude Pech Alain Latché 《Physiologia plantarum》1995,94(4):629-634
A 36-kDa 1-aminocyclopropane-1-carboxylate (ACC) N-malonyltransferase, which converts the ethylene precursor ACC into the conjugated derivative malonyl-ACC (MACC), has been isolated from etiolated mung bean ( Vigna radiata ) hypocotyls, and partially purified in a four-step procedure. The enzyme is stimulated about 7-fold by 100 m M K+ salts or 0.5 m M Co2+ salts, and is inhibited competitively by D-phenylalanine (Ki = 1.3 m M ) and non competitively by CoASH (0.3 m M ). Beside malonyl-CoA, it is capable to use succinyl-CoA as an acyl donor. The 36-kDa enzyme described here exhibits a lower optimum temperature (40°C) and a 7- or 3-fold lower apparent Km for ACC (68 μ M ) and malonyl-CoA (74 μ M ), respectively, when compared with its 55 kDa isoform already isolated from the same plant material. This data support the idea that several isoforms of ACC N-malonyltransferase exist in plants. These isoforms may play a differential role in regulating the availability of ACC, and consequently the rate of ethylene production, as well as detoxifying cells from D-amino acids. 相似文献
97.
Delhon Patricia; Gojon Alain; Tillard Pascal; Passama Lucien 《Journal of experimental botany》1995,46(10):1585-1594
The effect of light on NO3 utilization was investigatedin non-nodulated soybean (Clycine max L. Merr., cv. Kingsoy)plants during a 14/10 h light/dark period at a constant temperatureof 26C. A 3050% decrease of net NO3 uptake ratewas observed 26 h after the lights were turned off. Thiswas specifically due to an inhibition of NO3 influx asmeasured by 15N incorporation during 5 min. The absolute valuesof NO3 efflux depended on whether the labelling protocolinvolved manipulation of the plants or not, but were not affectedby illumination of the shoots. Darkness had an even more markedeffect in lowering the reduction of 15NO3 in both rootsand shoots, as well as xylem transport of 15NO3 and reduced15N. Concurrently with this slowing down of transport and metabolicprocesses, accumulations of NO3 and Asn were significantlystimulated in roots during the dark period. These data are discussedin view of the hypothesis that darkness adversely affects NO3uptake through specific feedback control, in response to alterationsin the later steps of N utilization which are more directlydependent on light. Key words: Glycine max, light/dark cycles, nitrate uptake, nitrate reduction 相似文献
98.
Magali Basille Bruno J. Gonzalez Laurence Desrues †Myriam Demas ‡Alain Fournier Hubert Vaudry 《Journal of neurochemistry》1995,65(3):1318-1324
Abstract: The presence of receptors for the novel neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) has been recently demonstrated in the external granule cell layer of the cerebellum, a germinative matrix that generates the majority of cerebellar interneurons. In the present study, we have taken advantage of the possibility of obtaining a culture preparation that is greatly enriched in immature cerebellar granule cells to investigate the effect of PACAP on the adenylyl cyclase and phospholipase C transduction pathways. The two molecular forms of PACAP, i.e., 27-(PACAP27) and 38-(PACAP38) amino-acid forms of PACAP, induced a dose-dependent stimulation of cyclic AMP production in granule cells. The potencies of PACAP27 and PACAP38 were similar (ED50 = 0.12 ± 0.01 and 0.23 ± 0.07 n M , respectively), whereas vasoactive intestinal polypeptide (VIP) was ∼100 times less potent. PACAP27 and PACAP38 also induced a dose-dependent stimulation of polyphosphoinositide breakdown (ED50 = 19.1 ± 6.3 and 13.4 ± 6.0 n M , respectively), whereas VIP had no effect on polyphosphoinositide metabolism. The effect of PACAP38 on inositol phosphate formation was significantly reduced by U-73122 and by pertussis toxin, indicating that activation of PACAP receptors causes stimulation of a phospholipase C through a pertussis toxin-sensitive G protein. In contrast, forskolin and dibutyryl cyclic AMP did not affect PACAP-induced stimulation of inositol phosphates. Taken together, the present results demonstrate that PACAP stimulates independently the adenylyl cyclase and the phospholipase C transduction pathways in immature cerebellar granule cells. These data favor the concept that PACAP may play important roles in the control of proliferation and/or differentiation of cerebellar neuroblasts. 相似文献
99.
Marc Mathieu Christian Lehmann Alain Razaname Gabriele Tuchscherer 《Letters in Peptide Science》1997,4(2):95-100
The assembly of helical and -sheet peptide blocks containing reactive chain ends results inhighly branched chain architectures (locked-in folds) mimicking native tertiary structures.This molecular kit strategy allows to bypass the protein folding problem in protein de novodesign and gives access to protein mimetics of high thermodynamic stability. The validity ofthis concept is exemplified for the design and synthesis of locked-in folds mimicking the zincfinger and MHC folding motifs. 相似文献
100.
François-Yves Dupradeau Guillaume Le Flem Jean-Michel Wieruszeski Manuel Dauchez Alain Alix Véronique Larreta-Garde Jean-Pierre Monti 《Letters in Peptide Science》1997,4(4-6):489-495
H-NMR studies of the bovine insulin S-sulfonatedB-chain are reported in H2O/D2O (9/1) and inglycerol-d5 (5 M) using two-dimensional NMRspectroscopy. The first results show that the oxidizedinsulin B-chain secondary structure differs from thatof native insulin by a loss of the -helixbetween the two disulfide bridges and that theglycerol favours the structuring of the peptide. 相似文献