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L Riviere

Publications and source records attributed to L Riviere.

8 recordsLinked to original sources
PubMed1990

Smooth muscle and brain inositol 1,4,5-trisphosphate receptors are structurally and functionally similar.

Inositol 1,4,5-trisphosphate (InsP3) mediates smooth muscle contraction by mobilizing intracellular calcium release. In this study we provide a direct comparison of the smooth muscle and brain InsP3 receptors in terms of InsP3 binding and primary structure. The KD for InsP3 binding for both receptors was found to be essentially the same. Sequences from 11 bovine smooth muscle receptor tryptic peptides (120 amino acids) were identified in the mouse brain receptor with two substitutions attributable to species differences. A cDNA (approximately 1-kilobase) encoding a portion of the mouse smooth muscle InsP3 receptor was cloned and found to be identical to that reported for the brain receptor. This cDNA was used as a probe to demonstrate that the approximately 10-kilobase InsP3 receptor mRNA is detected in brain, smooth muscle, heart, liver, and kidney but was not detected in skeletal muscle or skin.

Amino Acid Sequence↗
PubMed1990

Isolation and characterization of abaecin, a major antibacterial response peptide in the honeybee (Apis mellifera).

Honeybee (Apis mellifera) are frequently exposed to and likely to be infected by plant-associated bacteria. We mimicked this process by injecting bees with live bacteria and isolated five induced antibacterial substances by comparative liquid chromatographic mapping of the hemolymph. Three of these antibiotics belong to a unique family of small (18 amino acids) peptides: the apidaecins [Casteels et al. (1989) EMBO J. 8, 2387-2391]. We have now characterized a fourth bee immune response peptide. The complete sequence was established by Edman degradation of the peptide and fragments thereof. It is 34 amino acids long and contains 10 proline residues. The amino-terminal half is related to the apidaecins; similar proline motifs are also present in the amino-terminal quarter of the much longer fly diptericins. The newly identified peptide's broad spectrum, lower specific activities against Gram-negative plant pathogens and its inability to inhibit bacterial growth at medium ionic strength are different from the apidaecins. Moreover, the highest observed specific activity was against an apidaecin-resistant Xanthomonas strain. In contrast to the immediate action of apidaecins, bactericidal activity is delayed. We propose the name 'abaecin' for this new antibacterial response peptide.

Amino Acid Sequence↗
PubMed1989

Examination of automated polypeptide sequencing using standard phenyl isothiocyanate reagent and subpicomole high-performance liquid chromatographic analysis.

The feasibility of accurate protein sequencing at the subpicomole level, using automated Edman chemistry and "on-line" HPLC analysis, was studied. Several modifications of the standard system were first introduced. A larger portion of the phenylthiohydantoin amino acids (70%) is analyzed. Dissolution in 10% acetonitrile is improved by short periodic bursts of argon. Losses on the column of subpicomole amounts of analytes, in the presence and absence of scavengers, were quantitated; they are related to destruction rather than to unspecific sticking to the stationary phase. Baseline drift, for a large part caused by the presence of ultraviolet absorbing N,N-dimethylphenylthiourea in solvent B, is completely eliminated by the addition of a twofold molar excess of tryptophan to solvent A. This allows real time recording of the 269-nm absorption detector signal at 0.0005 absorption unit full scale. The combined modifications result in an eightfold increase in sensitivity over standard methods. Sequence calling at the 2 to 10 pmol level, through visual inspection of chromatograms, becomes increasingly simple this way. Once the sequenceable signal drops below the 1 pmol level in the course of a run, meticulous comparison and matching of the preliminary calls with a spreadsheet of peak integration data are necessary for accurate assignments. Reliable sequencing, with signals at the subpicomole level, is now feasible for stretches of over 10 residues. Contaminating amino acids and polypeptides and incompletely removed reaction by-products constitute a major problem for analysis at this level. Future limits to sensitivity of Edman sequencing will primarily depend on improved micropreparations of proteins in cleaner environments, higher purity reagents and solvents, instrument miniaturization, and solid-phase techniques.

Amino Acid Sequence↗
PubMed1988

Characterization of alpha-mannosidase in feline mannosidosis.

Acidic alpha-mannosidase deficiency has been identified in a family of Blue Persian cats. Characterization of the residual activity revealed that the Km for the substrate, 4-methylumbelliferyl-alpha-D-mannoside, increased approximately three-fold with a severe deficiency in Vmax (1-2%) in homogenates of liver and brain of affected cats compared with controls. The residual activity at pH 4.0 in liver homogenates from affected cats is very thermolabile at 51 degrees C while the control activity is stable at this temperature for 1 h. Subcellular fractionation of liver was performed from a control and diseased cat in order to compare the properties of the different alpha-mannosidases localized in these fractions. The residual activity present in the lysosomal fraction from diseased cat liver showed altered pH optimum, two-fold increase in Km with a severely reduced Vmax and increased thermolability compared with the activity in the lysosomal fraction from control liver. The thermal inactivation pattern and Km of the residual activity in the lysosomal fraction is different from the non-lysosomal alpha-mannosidase in the liver of the affected cat. This suggests that the residual activity in the lysosomal fraction of the liver from the affected cat is not due to contamination of non-lysosomal alpha-mannosidase in this fraction. Whether this residual activity represents the properties of the mutant enzyme or yet another minor normal component of lysosomes different from the major inactive mutant or absent lysosomal enzyme remains to be elucidated.

Animals↗
PubMedDate not supplied

[Gonadal dysgenesis in a mother and her daughter (author's transl)].

The authors present two cases of gonadal dysgenesis in a mother and her daughter. Caryotypes were 46, XX/45, X for the mother (RHG-banding) and 46, X, i (Xq)/45, X for the daughter. Some researches in family did not show any abnormalities to explain this very exceptionnel event in a mother and one of her 3 daughters.

Adolescent↗