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Biomedical subjects

M Delarue

Publications and source records attributed to M Delarue.

65 records · Page 4Linked to original sources
PubMed1985

Translation of Schistosoma mansoni antigens in Xenopus oocytes microinjected with mRNA from adult worms.

Oocytes from Xenopus laevis microinjected with RNA isolated from Schistosoma mansoni adult worms translated antigens recognized by sera from infected rats, humans, and from immunized rabbits. The pattern of immunoprecipitated proteins analysed by SDS-polyacrylamide gel electrophoresis was species specific in rats. Serum from infected Fischer rats recognized antigens of 20, 27 and several bands in the 50-60 kDa range whereas serum from infected Brown Norway rats also immunoprecipitated major bands at 29, 43 and 100 kDa. Human infection sera gave a very variable pattern of immunoprecipitation not apparently dependent on the patients' age. At least 20 different antigenic species could be identified ranging from 14 to 150 kDa. Some S. mansoni antigenic proteins could be isolated from the membrane fraction of the oocytes whereas notably the 29 kDa band was present mainly in the soluble fraction. N-Glycosylation of S. mansoni antigens occurred as evidenced by the effects of tunicamycin treatment and concanavalin A binding. A multiple series of bands between 50 and 60 kDa, present in the membrane fraction, were glycosylated and secreted from the oocytes. Monoclonal antibodies to larval stage surface antigens failed to immunoprecipitate oocyte translation products, but sera absorbed with live schistosomula identified at least three putative surface antigens of 100, 43 and 29 kDa. However, the 29 kDa molecule was neither synthesized into membranes, nor secreted from oocytes.

Animals↗
PubMed1984

Oligodeoxynucleotides covalently linked to intercalating dyes as base sequence-specific ligands. Influence of dye attachment site.

New molecules with high and specific affinity for nucleic acid base sequences have been synthesized. They involve an oligodeoxynucleotide covalently attached to an intercalating dye. Visible absorption spectroscopy and fluorescence have been used to investigate the binding of poly(rA) to octadeoxythymidylates substituted by a 9-aminoacridine derivative in different positions along the oligonucleotide chain. The 9-amino group of the acridine dye was linked through a polymethylene bridge to the 3'-phosphate, the 5'-phosphate, the fourth internucleotidic phosphate or to both the 3'- and 5'-phosphates. Different interactions of the acridine dye were exhibited by these different substituted oligodeoxynucleotides when they bind to poly(rA). The interaction was shown to be specific for adenine-containing polynucleotides. The stability of these complexes was compared with that of oligodeoxynucleotides substituted by an alkyl group on the 3'-phosphate. The increase in stability due to the presence of the intercalating dye has been determined from the comparison of melting temperatures. These results are discussed with respect to the strategy of synthesis of a new class of molecules with high affinity and high specificity for nucleic acid base sequences.

Aminacrine↗
PubMed1984

Nucleic acid-binding molecules with high affinity and base sequence specificity: intercalating agents covalently linked to oligodeoxynucleotides.

Oligodeoxyribonucleotides covalently linked to an intercalating agent via a polymethylene linker were synthesized. Oligothymidylates attached to an acridine dye (Acr) through the 3'-phosphate group [(Tp)n(CH2) mAcr ] specifically interact with the complementary sequence. The interaction is strongly stabilized by the intercalating agent. By using absorption and fluorescence spectroscopies, it is shown that complex formation between (Tp)n(CH2) mAcr and poly(rA) involves the formation of n A X T base pairs, where n is the number of thymines in the oligonucleotide. The acridine ring intercalates between A X T base pairs. Fluorescence excitation spectra reveal the existence of two environments for the acridine ring, whose relative contributions depend on the linker length (m). The binding of (Tp)4(CH2) mAcr to poly(rA) is analyzed in terms of site binding and cooperative interactions between oligonucleotides along the polynucleotide lattice. Thermodynamic parameters show that the covalent attachment of the acridine ring strongly stabilizes the binding of the oligonucleotide to its complementary sequence. The stabilization depends on the linker length; the compound with m = 5 gives a more stable complex than that with m = 3. These results open the way to the synthesis of a family of molecules exhibiting both high-affinity and high-specificity for a nucleic acid base sequence.

Acridines↗
PubMed1983

Regulation of cell cycle by cytoplasmic components in the amphibian eggs.

Injections of extracts of Xenopus egg cytoplasm induce precocious cleavage furrows in activated Pleurodeles eggs. This cleavage timing system (CTS) activity is retained in two distinct fractions separated by gel filtration. Acceleration of the first cell cycle of the Pleurodeles egg is directly related to the concentration of the injected extracts. However, the maximum advance of the cleavage cycle does not exceed 25 to 30% of the control cycle. Preliminary characterization of these fractions indicates that the CTS effect is abolished after protease but not RNAse treatment, and that the CTS factors are thermostable. The phase of the egg cell cycle sensitive to the CTS factors, which act as a 'clock system mechanism', is discussed.

Animals↗
PubMed1981

Cytoplasmic regulation of the duration of cleavage in amphibian eggs.

Relations between a cytoplasmic species specificity and the duration of cleavage cycles were investigated by reciprocal injections of egg cytoplasm. Xenogenic cytoplasm induces an early or delayed cleavage of the recipient egg depending on the chronological specificity of the injected cell cytoplasm. Activity of the so-called cleavage timing system (CTS) was first detected in the cytoplasm of maturing oocytes at the stage of germinal vesicle breakdown (GVBD). This specific cytoplasmic property was not dependent on the maturation promoting factor (MPF). Relations between the CTS and other cytoplasmic components which are known to induce cleavage are discussed.

Animals↗
PubMed1977

[Consequence of heterospecific cytoplasmic graft on gastrulation of Bufo bufo L. (Amphibia, Anura)].

Bufo bufo nuclei were grafted in virgin and enucleated Bufo calamita eggs. In these conditions embryonnic development was stopped at the early gastrula stage in 92% of the recipient eggs. For accomparative analysis Bufo calamita cytoplasm was injected into fertilized Bufo bufo eggs and produce arrest of development at the early gastrula stage. The progressive enhancement of this development inhibition was related to the increasing of the injected cytoplasm volume.

Animals↗
PubMed1976

[Modification by heterspecific cytoplasm injection, of the chronology of the first division of the Amphibia ovum].

Transfer of cytoplasm had been made between virgin eggs of two species, species with very different times between activation of the eggs and the first cleavage. The first furrow appears on an average of 6 hrs. after activation in Pleurodeles eggs and 2 hrs. 30 min. in Xenopus eggs. Slow cleaving P. waltlii cytoplasm introduced in quickly cleaving X. laevis eggs acted by delaying the formation of the first cleavage furrow, which appeared more than an hour after Xenopus controls. An opposite effect was obtained with Xenopus cytoplasm in Pleurodeles eggs. Cleavage furrows were obtained 2 hrs. before Pleurodeles controls. The cytoplasmic effect involved in the control of rhythms of cleavage could be related to a clock system.

Amphibians↗
PubMedDate not supplied

The amphibian embryo: an experimental model for the in vivo analysis of interactions between embryonic cells and extracellular matrix molecules.

The early amphibian embryo provides an attractive model for the in vivo analysis of cell interactions with extracellular matrix components. During gastrulation, mesodermal cells use an anastomosing network of extracellular fibrils as substratum for their migration. These fibrils contain glycosaminoglycans and non collagenous proteins including laminin and fibronectin. The function of these extracellular components in the mesodermal cell migration process has been inferred from grafting experiments and microinjection of probes such as specific antibodies or GRGDS-containing peptides. Using the amphibian embryo as an experimental system, combination of microsurgical, cell behavioral and molecular approaches will provide new insights into cell-extracellular matrix interactions directing morphogenetic cell movements.

Amino Acid Sequence↗